\documentclass[10pt]{article}

\usepackage{fullpage}
\usepackage{setspace}
\usepackage{parskip}
\usepackage{titlesec}
\usepackage[section]{placeins}
\usepackage{xcolor}
\usepackage{breakcites}
\usepackage{lineno}
\usepackage{hyphenat}





\PassOptionsToPackage{hyphens}{url}
\usepackage[colorlinks = true,
            linkcolor = blue,
            urlcolor  = blue,
            citecolor = blue,
            anchorcolor = blue]{hyperref}
\usepackage{etoolbox}
\makeatletter
\patchcmd\@combinedblfloats{\box\@outputbox}{\unvbox\@outputbox}{}{%
  \errmessage{\noexpand\@combinedblfloats could not be patched}%
}%
\makeatother


\usepackage{natbib}




\renewenvironment{abstract}
  {{\bfseries\noindent{\abstractname}\par\nobreak}\footnotesize}
  {\bigskip}

\titlespacing{\section}{0pt}{*3}{*1}
\titlespacing{\subsection}{0pt}{*2}{*0.5}
\titlespacing{\subsubsection}{0pt}{*1.5}{0pt}


\usepackage{authblk}


\usepackage{graphicx}
\usepackage[space]{grffile}
\usepackage{latexsym}
\usepackage{textcomp}
\usepackage{longtable}
\usepackage{tabulary}
\usepackage{booktabs,array,multirow}
\usepackage{amsfonts,amsmath,amssymb}
\providecommand\citet{\cite}
\providecommand\citep{\cite}
\providecommand\citealt{\cite}
% You can conditionalize code for latexml or normal latex using this.
\newif\iflatexml\latexmlfalse
\providecommand{\tightlist}{\setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}%

\AtBeginDocument{\DeclareGraphicsExtensions{.pdf,.PDF,.eps,.EPS,.png,.PNG,.tif,.TIF,.jpg,.JPG,.jpeg,.JPEG}}

\usepackage[utf8]{inputenc}
\usepackage[ngerman,greek,english]{babel}
\usepackage{CJKutf8}



\usepackage{float}








\begin{document}

\title{Li-containing alloys beneficial for stabilizing lithium anode: a review}



\author[1]{Xingxing Gu}%
\author[2]{Jing Dong}%
\author[2]{Chao Lai}%
\affil[1]{Chongqing Technology and Business University}%
\affil[2]{Jiangsu Normal University}%


\vspace{-1em}



  
  \date{June 17, 2024}


\begingroup
\let\center\flushleft
\let\endcenter\endflushleft
\maketitle
\endgroup





\selectlanguage{english}
\begin{abstract}
Due to the soaring growth of the electric vehicles and grid energy
storage markets, the high-safety and high-energy-density battery storage
systems are urgent needed. Lithium metal anode with highest theoretical
specific capacity (3860 mA\selectlanguage{ngerman}·h·g\selectlanguage{english}-1) and the lowest electrochemical
potential (\selectlanguage{english}-3.04 V vs standard hydrogen electrode) is regarded as the
ultimate choice for the high energy density batteries. However, its
safety problems as well as the low Coulombic efficiency during the Li
plating and stripping processes significantly limit the
commercialization of lithium metal batteries. Recently, Li-containing
alloys have demonstrated vital roles in inhibiting lithium dendrite
growth, controlling interfacial reactions and enhancing the Coulombic
efficiency as well as cycle life. Accordingly, in this perspective, the
progresses of lithium alloys for robust, stable and dendrite free anode
for rechargeable lithium metal batteries are summarized. The challenges
and future focus research of lithium-containing alloys in lithium metal
batteries are also discussed.%
\end{abstract}\selectlanguage{ngerman}%



\sloppy


\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
\emph{REVIEW ARTICLE} &\tabularnewline
\bottomrule
\end{longtable}

\textbf{Li-containing alloys beneficial for stabilizing lithium anode: a
review}

\textbf{Xingxing Gu\textsuperscript{1+}\textbar{} Jing
Dong\textsuperscript{2+} \textbar{} Chao Lai*\textsuperscript{2}}\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
\textsuperscript{1}Chongqing Key Laboratory of Catalysis and New
Environmental Materials, College of Environment and Resources, Chongqing
Technology and Business University, Chongqing, China
\textsuperscript{2}School of Chemistry and Materials Science, Jiangsu
Normal University, Xuzhou, China \textsuperscript{+}These authors
contributed equally to this work \textbf{Correspondence} *Chao Lai,
School of Chemistry and Materials Science, Jiangsu Normal University,
Xuzhou, China. Email: \emph{laichao@jsnu.edu.cn} \textbf{Funding
Information} National Natural Science Foundation of China Grant/Award
Number: 51871113 and 51902036 Natural Science Foundation of Chongqing
Science \& Technology Commission Grant/Award Number:
cstc2019jcyj-msxm1407 Natural Science Foundation of Chongqing Technology
and Business University Grant/Award Number: 1952009 Key Research and
Development Program of Xuzhou Grant/Award Number: KC17004 Science and
Technology Research Program of Chongqing Education Commission
Grant/Award Number: KJQN201900826 and KJQN201800808 Venture \&
Innovation Support Program for Chongqing Overseas Returnees Grant/Award
Number: CX2018129 Innovation Group of New Technologies for Industrial
Pollution Control of Chongqing Education Commission Grant/Award Number:
CXQT19023 & \textbf{Abstract} Due to the soaring growth of the electric
vehicles and grid energy storage markets, the high-safety and
high-energy-density battery storage systems are urgent needed. Lithium
metal anode with highest theoretical specific capacity (3860
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1}) and the lowest electrochemical potential
(\selectlanguage{english}-3.04 V vs standard hydrogen electrode) is regarded as the ultimate
choice for the high energy density batteries. However, its safety
problems as well as the low Coulombic efficiency during the Li plating
and stripping processes significantly limit the commercialization of
lithium metal batteries. Recently, Li-containing alloys have
demonstrated vital roles in inhibiting lithium dendrite growth,
controlling interfacial reactions and enhancing the Coulombic efficiency
as well as cycle life. Accordingly, in this perspective, the progresses
of lithium alloys for robust, stable and dendrite free anode for
rechargeable lithium metal batteries are summarized. The challenges and
future focus research of lithium-containing alloys in lithium metal
batteries are also discussed. \textbf{KEYWORDS} dendrite free, lithium
battery, lithium alloys, lithium metal anode\tabularnewline
\bottomrule
\end{longtable}\selectlanguage{ngerman}

\section*{Introduction}

{\label{introduction}}

The metallic lithium as an anode in a rechargeable battery was first
explored by Whittingham in 1970s at Exxon and realized commercialization
by Moli Energy in the late 1980s{[}1-3{]}, but frequent accidents,
including fires caused by dendrite formation, brought serious safety
issues to public attention, which leaded to the Moli Energy company
ultimately recall all the cells. The first commercialization of
lithium-metal anode rechargeable batteries ended in failure. Then Sony
company developed the graphite anodes to replace metallic Li anode,
matched with the LiCoO\textsubscript{2} cathode, successfully built
reliable Li-ion cells that have been widely used until now{[}2, 4-6{]}.
However, with the booming growth in consumer electronic devices and
electric vehicles, even the state-of-the-art lithium ion batteries
(LIBs) using graphite anodes (with a theoretical specific capacity of
372 mA*h*g\textsuperscript{--1}) have almost reached their theoretical
energy density (350 Wh*kg\textsuperscript{--1}), cannot provide the high
energy density required for their demands{[}7-10{]}.

Therefore, recently, particularly in recent 10 years, the rechargeable
lithium metal batteries using the Li anode has acquired unprecedented
attentions as it has the unsurpassably highest theoretical capacity
(3860 mA*h*g\selectlanguage{english}\textsuperscript{-1}, or 2061 mA*h*cm\textsuperscript{--3})
and lowest electrochemical potential (--3.04 V versus the standard
hydrogen electrode){[}2, 11-15{]}. Additionally, with rapid development
of cathodes alternative to conventional intercalation cathodes used in
state-of-the-art Li-ion batteries, i.e., the sulfur (S) cathode (with
energy density of \selectlanguage{english}[?]2600 Wh*kg\textsuperscript{--1}) for the Li-S battery
and the oxygen cathode (with energy density of \selectlanguage{english}[?]11140
Wh*kg\textsuperscript{--1}) for the Li-air battery{[}16, 17{]}, have
undoubtedly hastened the arrival of rechargeable Li metal batteries.

However, the safety issues by using the Li anode as well as its poor
cycle stability and low Coulombic efficiency are still not overcome and
hinds its practical applications. Tremendous efforts have been devoted
to solving the notorious lithium dendrite problem by employing advanced
electrolytes, separators, and novel electrode materials/structures. In
the aspect of electrolyte, increasing the concentrations of lithium
salts and adding inorganic or organic additives in electrolyte could not
only benefit to stabilize the spontaneous solid electrolyte interphase
(SEI) films to reduce the side reactions happening, but also control the
nucleation and growth of metallic lithium, thus enhancing the
stabilities of lithium anodes during the stripping and plating
processes{[}18-22{]}. Recently, our group employed octaphenyl
polyoxyethylene as an electrolyte additive to enable a stable complex
layer on the surface of the lithium anode. This surface layer not only
promoted uniform lithium deposition, but also facilitated the formation
of a robust SEI film{[}23{]}. While developed new type of modified
separators are expected to physically suppress the growth of lithium
dendrites. For instance, in situ fabricating a stable
tissue-directed/reinforced bifunctional separator/protection film (TBF)
on the surface of the Li anode effectively protected lithium from the
corrosion of O\textsubscript{2}, discharge intermediates,
H\textsubscript{2}O and electrolyte, and reduce morphology change of the
surface of lithium anode{[}24{]}. In terms of novel electrode
materials/structures, infusion the Li metal into a carbon framework or
synthesis of lithium-based composites{[}25-27{]}, enables to control the
growth of lithium dendrites, but also solves the infinite volume change
issue of lithium-based electrodes{[}18, 28{]}. For instance, Koratkar
and co-workers described defect-induced plating of metallic lithium
within the interior of a porous graphene network{[}27{]}. The network
acted as seed points that initiated plating of lithium metal and
prevented dendritic growth.

Based on the aforementioned considerations, stable operation of Li metal
anodes, no matter inhibit the lithium dendrite growth or controllable
side reaction and volume change, is critical for next-generation battery
technologies. Thus, in this short perspective article, we briefly review
the Li-containing alloys reported in the literatures to stabilize Li
metal anodes and propose a few new suggestions for protecting the Li
metal by reasonably combining the lithium-containing alloys with other
strategies.

\section*{Failure Mechanisms of Metallic Lithium
Anodes}

{\label{failure-mechanisms-of-metallic-lithium-anodes}}

Before introducing the practical applications of lithium alloy in
present metal lithium batteries, it is necessary to understand the
failure mechanisms of lithium anode. Actually, during the past 10 years,
deep and fundamental understanding on the failure mechanisms of the Li
metal anode has been extensively discussed. No matter in LIBs, Li-S,
Li-O\textsubscript{2} or solid-state electrolyte Li-metal batteries,
generally, these issues will cause the failure of Li anode{[}29-31{]}:

i) Uncontrolled interfacial reactions: the uncontrolled interfacial
reaction also called the side reactions that happen on the Li-metal
surface with the organic electrolytes. As the high reactivity of
Li-metal in the organic electrolyte, it easily appears corrosive
reactions to deplete the electrolytes and generate thick SEI layers,
which will lead to increasing resistance and low Coulombic
efficiency{[}29{]}.

ii) Uncontrollable Li dendrite growth: the Li dendrites could penetrate
through the separator and cause cell short circuit, resulting in a
series of safety concerns{[}32{]}. Meanwhile, the dendritic Li could
also produce so-called ``dead Li'' via electrical detachment of Li from
the current collector; significantly affect the cycle life of the
Li-metal battery{[}32{]}. And now it is widely accepted that unstable
and inhomogeneous SEI films, inhomogeneous electric fields, and
inordinate lithium-ion \selectlanguage{english}flux are the origination of the dendrite
growth{[}2, 18{]}.

iii) Infinite relative volume changes: as the ``hostless'' nature of Li,
during repeated stripping/plating process, the relative volume change of
Li anode is virtually infinite, which will initiate cracks on the SEI,
leading high structural instability for the Li anode{[}2{]}. As the
specific example illustrated in the previous report{[}2, 33{]}, a
single-sided commercial electrode needs to reach an areal capacity of 3
mA*h*cm\textsuperscript{--2}, indicating a huge change in thickness of
\textasciitilde{}14.6 \selectlanguage{greek}μ\selectlanguage{english}m for Li. In terms of future applications, this
value could be even higher, really a formidable challenge on the SEI
stability.

\section*{How Li-containing alloys solving the present
issues?}

{\label{how-li-containing-alloys-solving-the-present-issues}}

The first use of lithium alloys as negative electrodes in commercial
batteries to operate at ambient temperatures was the employment of
Wood's metal alloys in lithium-conducting button type cells by
Matsushita in Japan. Development work on the use of these alloys started
in 1983{[}34, 35{]}, and they became commercially available somewhat
later{[}35{]}. Since then, researchers not only used the lithium alloys
as the anodes to reduce the activity of Li anode and stabilize
it{[}36{]}, but also developing various kinds of other strategies, i.e,
constructing rational design of anode structure (3D hosts and 3D current
collectors){[}25, 37{]}, suppressing Li dendrite growth via modification
of electrolytes, separators and anode interfacial engineering{[}2,
38{]}, etc.

\section*{3.1 \textbar{} DIRECTLY USING LITHIUM ALLOYS TO REPLACE
METALLIC LITHIUM AS
ANODE}

{\label{directly-using-lithium-alloys-to-replace-metallic-lithium-as-anode}}

The lithium-free alloy anodes, such as Sn-Sb, Sn-Co, Ni-Sn alloy, etc.,
without pre-stored lithium, the overall energy density is limited by the
low-capacity lithium metal oxide cathodes, while the pure lithium metal
anode face its high reactivity and uncontrolled dendrite growth{[}39{]}.
Li-containing alloy anodes inheriting the desirable properties of alloy
anodes and pure Li metal anodes. Lithium alloy anodes for rechargeable
ambient temperature lithium batteries have been studied since the early
1970{[}40, 41{]}. During the past 40 years, great deals of literatures
have been reported using the lithium-containing alloys as the anode
materials for lithium ion batteries{[}18, 30, 32-34, 38, 42-44{]}. They
can effectively reduce Li nucleation overpotential and decrease
interfacial resistance, guiding the formation and growth of
non-dendritic Li{[}25{]}. Among these lithium alloys anode, they can
mainly divided into two categories: binary lithium alloys and ternary
lithium alloys. And different lithium alloys anodes have their own
advantages and disadvantages.

For example, Li-Si alloy anodes exhibit multiple attractive properties:
i) fully lithiated Li\emph{\textsubscript{x}} Si alloy has a
sufficiently low potential of around 10 mV versus
Li/Li\textsuperscript{+} to prelithiate all types of anodes including
graphite, Si, Ge and Sn{[}45{]}; ii) due to the super-high capacity of
Si (4200 mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1}), Li\emph{\textsubscript{x}} Si
alloy anode could also illustrate high specific capacity even a small
percentage of pre-storing lithium, i.e., Li\textsubscript{4.4}Si shows a
capacity of 2000 mA*h*g\selectlanguage{english}\textsuperscript{-1} {[}45{]}. Most of the Li-Si
electrodes were obtained by electrochemical lithiation of Si-based
electrodes{[}46-48{]}, which is very difficult to employ for practical
application{[}47{]}. But recently, there have been reported other two
methods to synthesis the Li-Si alloy: one is pressing plus
heat-treatment process as shown in Figure 1a{[}47{]}, another one is
ball milling method (Figure 1b) at argon atmosphere{[}49-51{]}.

Except the Li\emph{\textsubscript{x}} Si alloy, the lithium alloy anodes
of other IVA group elements has also been widely reported, such as Li-Sn
and Li-Ge alloy anodes{[}48, 52-58{]}. Similar as
Li\emph{\textsubscript{x}} Si alloy, the Li-Sn and Li-Ge alloy anodes
also exhibit relative high specific capacity{[}48, 57{]}. While the
Li-Sn alloy anode also shows its unique merits, including the fast
interdiffusion of Li in Sn and the \textless{} 500 mV separation between
Li-Sn alloy formation and Li plating. Archer's group reported a Li-Sn
hybrid battery anodes created by depositing an electrochemically active
Sn on a reactive Li metal electrode by a facile ion-exchange chemistry
as shown in Figure 1c, leading to very high exchange currents and stable
long-term performance{[}59{]}. The Li-Sn anodes were shown to be stable
at 3 mA*cm\selectlanguage{english}\textsuperscript{-2}and 3 mA*h*cm\selectlanguage{english}\textsuperscript{-2}. While
in contrast to Si, Ge has the benefit of forming a minimal amount of
native oxide in its outermost layer and the diffusivity of lithium in Ge
is 400 times greater than that of lithium in Si at room temperature, but
as the high cost of Ge, the Li-Ge alloy anodes have not gained much
attention{[}34{]}.

The Li-Al alloy anode showed higher stability in the air,
carbonate-based electrolyte and the electrolyte with
LiNO\textsubscript{3} additive{[}60, 61{]}. Also, Al alloying with Li
exhibits much smaller volume change (\selectlanguage{english}[?]96\%) compared with other alloy
anodes, such as Li-Si (320\%) and Li-Sn (260\%) alloys anode{[}62{]}. In
addition, Li diffusion coefficient in Li-Al alloy
(6.0x10\textsuperscript{-10}cm\textsuperscript{2}*s\selectlanguage{english}\textsuperscript{-1})
exceeds that in bulk Li metal
(5.69x10\textsuperscript{-11}cm\textsuperscript{2}*s\selectlanguage{english}\textsuperscript{-1}){[}63{]}.
LiB alloy is widely used as anode in thermal battery, which can be
regarded as free metal lithium metal filled in the fibrillar network
framework of Li/B compound (Li\textsubscript{7}B\textsubscript{6}){[}64,
65{]}, such a porous structure can increase the specific surface area
and adjust Li ions even distribution. As the discharge potential of
Li\textsubscript{7}B\textsubscript{6} is over 0.4 V (vs.
Li/Li\textsuperscript{+}), thus when Li-B alloy used in metal lithium
battery, its free metal lithium participates in electrochemical reaction
preferentially{[}64{]}. Additionally,
Li\textsubscript{7}B\textsubscript{6} has a good conductivity
(1.43x10\textsuperscript{3}\selectlanguage{english}\selectlanguage{english}\textsuperscript{-1}*cm\selectlanguage{english}\textsuperscript{-1})
and a high Li ion diffusion rate comparative to metallic
lithium{[}64{]}. Thus, in 2013, Yang's group firstly investigated Li-B
alloy as anode for lithium/sulfur battery{[}64{]}. It is because of the
above advantages, Li-B alloy has better behaviors in restraining the
formation of dendritic lithium, reducing the interface impedance of
electrode and improving the cycle performance of the battery. For Li-In
alloy electrode, Archer's group found the interfacial of the resultant
Li-In alloy electrode was significant lower than that of the pristine Li
metal, which allowed Li ions diffused along the surface to form uniform
deposit on the hybrid electrode{[}66{]}. As a result of the enhanced
interfacial ion transport mechanism, compact and uniform
electrodeposition for the Li-In alloy anode at long time scales has been
realized. And the Li-In hybrid anodes to full cells employing
high-loading commercial cathodes (LTO and nickel manganese cobalt oxide)
showed that the electrodes can be cycled stably for over 250 cycles with
close to 90\% capacity retention. Recently, Adelhelm investigated the
different In/Li ratio on the performances of Li-In anode{[}67{]}. The
right In/Li ratio, i.e. 1.27:1, enabled stable lithium
insertion/deinsertion in symmetrical cells for at least 100 cycles;
while too much lithium in the electrode leaded to a drop in redox
potential combined with a rapid build-up of interface resistance.

Compared with the group IVA and group IIIA lithium alloys, even as early
as 1970s, the Li\textsubscript{3}Sb and Li\textsubscript{3}Bi alloy
anodes have also been investigated in metal lithium batteries{[}68,
69{]}, group VA lithium alloys directly used as anodes in metal lithium
batteries are not too many{[}43, 70-72{]}. That mainly because the
higher toxicity of some VA elements, such as Sb and As, and the smaller
gravimetric capacity of Bi{[}34{]}. In addition, the synthesis
conditions of VA lithium alloys are higher demanding, taking the Li-Sb
alloy, except complex prelithiation with Sb, another method is prepared
by electrolysis of the molten LiCl-KCl eutectic mixture with a liquid
antimony cathode at high-temperature{[}71{]}. In contrast, the
Bi/Sb-based nanocomposites and Bi/Sb-based intermetallics could be
easily and large-scale production, as well as demonstrated good
electrochemical performances when used as anode materials for
LIBs{[}34{]}. Therefore, during the past 40 years, there has been no
significant development of the group VA lithium alloys as the anodes in
metal lithium batteries.

Beside these three group elements, some other elements such as Na{[}73,
74{]}, Mg{[}75-80{]}, Zn{[}81, 82{]}, In{[}66, 67{]}, Ag{[}83, 84{]},
Au{[}84{]}, etc., can alloy with Li as well. And recently, these
lithium-alloys used as the anode materials in lithium metal batteries
have gained increasing attentions.

Li-Na alloy can supply Li\textsuperscript{+} on stripping and thus
ensure the electrostatic shield effect of Li\textsuperscript{+
{[}85{]}}. And Li-Na alloy would not sacrifice the specific capacity of
the anode because Li and Na metals exhibit similar reaction activities
as well as electrolyte compatibility of Li\textsuperscript{+} and
Na\textsuperscript{+ {[}85{]}}. However, developing a Li-Na alloy anode
might be difficult because of volume expansion{[}73, 74, 85{]}, which
causes SEI damage, large internal resistance and low Coulombic
efficiency. Recently, Zhang's group reported a Li-Na alloy anode used in
Li-O\textsubscript{2}batteries{[}85{]}. By optimizing the Na/Li value of
the alloy, a dendrite-suppressed, oxidation-resistant and crack-free
Li-Na alloy anode could be obtained{[}85{]}, thus realizing an alloy
anode with a long cycle life.

The Li-Mg alloy is advantageous because of the generally lower
reactivity of Li (or relatively low Li activity), the large solid
solution range, the mechanical integrity of Mg framework and a
relatively large diffusion coefficient of Li in Mg
(\selectlanguage{english}~10\selectlanguage{english}\textsuperscript{-7} cm\textsuperscript{2}*s\selectlanguage{english}\textsuperscript{-1} for
the Li-Mg alloy produced by vapor deposition){[}75, 77-79, 86{]}. Mg
alloying can increase lithium utilization, when no external pressure is
applied while pure lithium metal is superior for setups that allow stack
pressures in the MPa range{[}75{]}. And appropriate amount Mg, i.e, 10
at\%, introducing into Li metal anode can also effectively prevent
contact loss{[}75{]}. Due to these various advantages, recently, Gao's
group reported Li-Mg alloy as an anode for Li-S batteries{[}76{]}.
Compared to the metallic Li anode, the Li-Mg alloy showed remarkable
improvement on stability at the surface and in the bulk during cycling
as shown in Figure 1d and 1e. And they also found after Li stripping, a
conducting Li-poor Li-Mg alloy matrix was formed, facilitating
subsequent plating and diffusion of Li ions.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image1/image1}

\end{center}
\end{figure}

\textbf{Figure 1} (a) Illustration of the preparation process of
carbon-supported Li-Si alloy electrodes. (Reproduced from ref.{[}47{]},
with permission from Copyright \selectlanguage{ngerman}© 2018 The Royal Society of Chemistry.)
(b) Scheme illustrating the high-energy ball-milling process using Li
grains and Si powders as precursors. (Reproduced from ref.{[}49{]}, with
permission from Copyright © 2014 American Chemical Society.) (c) Hybrid
anodes based on facile and fast Sn deposition on reactive metals
produced by ion exchange in a common used aprotic liquid lithium
electrolyte, 1 M LiPF\textsubscript{6} in an ethylene carbonate-dimethyl
carbonate (EC/DMC) solvent blend containing a second salt. (Reproduced
from ref.{[}59{]}, with permission from Copyright © 2019 Elsevier Ltd..)
Surface morphology and elemental distribution of the cycled (d) Li metal
and (e) Li-Mg alloy anode retrieved from the cells after 100 cycles.
(Reproduced from ref.{[}76{]}, with permission from Copyright © 2019
WILEY-VCH.)

Even the theoretical of Li-Zn alloy is not as high as Li-Si, Li-Sn,
Li-Ge, Li-Sb alloys, etc., the volume expansion of Li-Zn alloys is not
obvious when used in Li storage{[}82{]}. Chen et al. reported a Li-Zn
alloy synthesized by depositing Li on the Zn substrate precursor at a
constant current density of 0.05 mA·cm\selectlanguage{english}\textsuperscript{-2} until the
potential reached 0 V (vs. Li/Li\textsuperscript{+}){[}82{]}. The
efficiency of Li deposition/stripping on the Li-Zn alloy anode remained
high at 96.7\% after 400 cycles at a current density of 0.1
mA*cm\selectlanguage{english}\textsuperscript{-2} and 250 cycles at the current density of 0.2
mA*cm\selectlanguage{english}\textsuperscript{-2}.

Different from the Si and Sn that experienced reconstitution reaction
with lithium to form alloys, Au and Ag, as two typical noble metals,
involve solid-solution reaction with Li to form
LiAu\emph{\textsubscript{x}} and
LiAg\emph{\textsubscript{x}}alloys{[}83, 84{]}. The solid-solution
reaction involves much less structure change than its counterpart (e.g.
Si and Sn) in the lithiation-delithiation process, therefore can take
place with a low charge-discharge voltage hysteresis at a potential that
is very close to that of Li/Li\textsuperscript{+} redox couple and
eliminate the nucleation barriers{[}83{]}. For example, in 2016, Cui's
group has found Au, Ag, Zn and Mg with good solubility in Li, once fully
lithiated, exhibited zero overpotential during deposition of Li as shown
in Figure 2a{[}84{]}. For materials Al and Pt have relatively small
solubility in Li metal and show small but observable overpotential for
Li nucleation (5 mV for Al, 8 mV for Pt); For materials showing no
solubility (Cu, Ni, C, Sn, Si) in lithium were also tested, as shown in
Figure 2b, all five materials show a clear overpotential for Li metal
nucleation. According to this vital findings, they designed Au nano
particles distributed inside the hollow carbon spheres to selectively
nucleate and grow Li metal inside carbon nanoshells during
electrochemical deposition, as shown in Figure 2c.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image2/image2}

\end{center}
\end{figure}

\textbf{Figure 2} (a) Voltage profiles of various materials with some
solubility in Li during Li deposition at a current density of 10
\selectlanguage{greek}µ\selectlanguage{english}A\selectlanguage{ngerman}·cm\selectlanguage{english}\textsuperscript{-2}. To enhance the comparison, the curves are
shifted horizontally according to the onset of lithium nucleation and
vertically with a constant shift of 0.05V. The scale of the y-axis is
indicated by the bar in the bottom left. (b) Shifted voltage profiles of
various materials with negligible solubility in Li during Li deposition
at a current density of 10 \selectlanguage{greek}µ\selectlanguage{english}A\selectlanguage{ngerman}·cm\selectlanguage{english}\textsuperscript{-2}. The horizontal
grey lines show 0 V versus Li in a and b. (c) Schematic of Li metal
nanocapsules design. Au NPs are loaded inside hollow carbon spheres,
where a large void space is reserved for Li metal. Li is expected to
nucleate from the Au seed. Carbon shells provide both confinement and
protection of the Li metal, as well as conduction channels for both
electrons and Li metal. (Reproduced from ref.{[}84{]}, with permission
from Copyright (c) 2016 Macmillan Publishers Limited.)

Even the binary Li-containing alloy systems, such as Li-Al, Li-Si,
Li-Sn, Li-Ge, Li-Sb, etc., possessed a particularly larger capacity than
the commercialized graphite, but these binary lithium alloy electrodes
usually suffered rather poor cycle performance as catastrophic
structural changes with large volume expansion{[}87{]}. To overcome this
poor reversibility in such intermetallic lithium alloy electrodes, the
ternary Li-containing alloy compounds have been investigated. For
example, Hashimoto et al. reported
Li\textsubscript{4.4}Ge\emph{\textsubscript{x}}
Si\textsubscript{1-\emph{x}} alloys synthesized by mechanically milling
process{[}88{]}. The Li\textsubscript{4.4}Ge\emph{\textsubscript{x}}
Si\textsubscript{1-\emph{x}} alloys formed a solid solution over the
whole composition range of 0\selectlanguage{english}[?]\emph{x} \selectlanguage{english}[?]1. Among the obtained alloys, the
Li\textsubscript{4.4}Ge\textsubscript{0.67}Si\textsubscript{0.33}alloy
showed the largest specific capacity of 190 mA*h*g\selectlanguage{english}\textsuperscript{-1}
and good charge-discharge reversibility. Yang et al. reported a ternary
Li\textsubscript{2.6}BMg\textsubscript{0.05}alloy as an alternative
anode to metallic lithium{[}89{]}. The pristine
Li\textsubscript{2.6}BMg\textsubscript{0.05} consists of rhombohedral
Li\textsubscript{5}B\textsubscript{4}, cubic lithium and
Li\textsubscript{3}Mg\textsubscript{7}. Therefore, it owns both the
advantages of Li--Mg alloy and Li--B alloy, which Li-Mg binary alloy
with good solid solution over a wide range of composition without phase
transformation, provides high specific capacity and Li-B alloy with
porous structure can increase the specific surface area and its very
negative potential close to pure lithium (ca. 20 mV vs.
Li/Li\textsuperscript{+}) provides a basic condition for the high energy
density. Pan et al, reported Li\textsubscript{2}MgSi as a novel anode
for Li-ion batteries{[}90{]}. Directly using Li\textsubscript{2}MgSi as
an anode material can prevent the dissociation of metallic Mg and/or
Li-Mg alloy from Mg\textsubscript{2}Si. And the pre-lithiated
Li\textsubscript{2}MgSi is likely to reduce the stress/strain during
delithiation/lithiation. In addition, by constructing a ternary alloy
that contain inactive materials, such as LiCuSn and LiCuSb alloy{[}87,
91{]}, the volume variation of active elements could be buffered by
inactive medium when active elements are dispersed uniformly in situ or
ex situ into the matrix of inactive components at nanoscale, as in the
cases of active/inactive composites and intermetallic compounds{[}92{]}.

Compared to plenty of binary Li-containing alloys anodes, there are few
reports on multi-component lithium alloy anodes{[}36, 87-91, 93-97{]}.
One reason is the much lower specific capacity of the ternary lithium
alloys, i.e,
Li\textsubscript{4.4}Ge\textsubscript{0.67}Si\textsubscript{0.33}{[}88{]},
Li\textsubscript{0.25}CuP{[}96{]}, etc., compared to the binary lithium
alloys; another most possible reason is rather difficult to prepare
high-purity multi-component lithium alloy{[}90{]}, as a result, the
theoretical capacities are hard to calculate as well as the
electrochemical mechanisms are difficult fully understood{[}87{]}.

\textbf{Table 1} The typical lithium alloys anodes employed in lithium
ion, Li-S and Li-O\textsubscript{2} batteries as well as their
advantages and disadvantages.\selectlanguage{english}
\begin{longtable}[]{@{}lllll@{}}
\toprule
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
\textbf{Categories}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
\textbf{Synthesized methods}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
\textbf{Advantages}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
\textbf{Disadvantages}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
\textbf{References}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Li-Si\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
fusion reaction method; electrochemical lithiation method; mechanical
ball milling method\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
superior high gravimetric capacity
(Li\textsubscript{21}Si\textsubscript{5}:1967
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1}); low potential of around 10 mV versus
Li/Li\textsuperscript{+}\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
great volume expansion; poor reversibility; difficult to realize
electrochemical lithiation into practical application; high
overpotential for Li metal nucleation\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
{[}39{]} {[}45{]} {[}46{]} {[}47{]} {[}48{]} {[}49{]} {[}50{]} {[}51{]}
{[}84{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Li-Sn\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
fusion reaction method; electrodeposition method; surface chemical
treatment method\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
high gravimetric capacity (Li\textsubscript{22}Sn\textsubscript{5}: 991
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1}); strong affinity towards metallic Li; small
interface impedance and fast lithium ion diffusion\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
great volume expansion; poor reversibility; high overpotential for Li
metal nucleation\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
{[}39{]} {[}52{]} {[}53{]} {[}54{]} {[}55{]} {[}56{]} {[}57{]} {[}59{]}
{[}84{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li-Ge\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
electrochemical lithiation method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
high gravimetric capacity (Li\textsubscript{17}Ge\textsubscript{4}: 1568
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1}); faster lithium diffusivity at room
temperature\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
great volume expansion, poor reversibility, high cost of Ge\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}48{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Li-B\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
fusion reaction method\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Porous structure for accommodating Li deposition; good conductivity
(1.43\selectlanguage{ngerman}×10\textsuperscript{3} \selectlanguage{english}\selectlanguage{english}\textsuperscript{-1}*
cm\selectlanguage{english}\textsuperscript{-1}); a high Li ion diffusion rate\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
easily porosity blocking and structure collapse, low hardness\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
{[}64{]} {[}65{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Li-Al\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
magnetron sputtering; fusion reaction method; electrochemical lithiation
method\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
higher stability in the air and electrolyte; smaller volume change;
lighter; working in high temperature (i.e. 450 \selectlanguage{ngerman}°C)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
moderate gravimetric capacity (550 mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1}); a very
narrow range of composition; phase transformations during cycling,
easily disintegrate or degrade; observable overpotential for Li
nucleation\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
{[}39{]} {[}42{]} {[}58{]} {[}60{]} {[}61{]} {[}62{]} {[}63{]}
{[}84{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Li-In\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
electroless plating method; electrochemical lithiation method\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
high electropositivity of lithium relative to indium; a constant redox
potential of about 0.6 V vs. Li\textsuperscript{+}/Li (0.5 V at 415 \selectlanguage{ngerman}°C);
minimal capacity fade\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
high cost\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
{[}66{]} {[}67{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li-Bi\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
electrochemical lithiation method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
high volumetric capacity (LiB\textsubscript{3}: 1760
mA\selectlanguage{ngerman}·h·cm\selectlanguage{english}\textsuperscript{-3}); working in high temperature
(\textgreater{} 380 degC)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
low gravimetric capacity (LiB\textsubscript{3}: 386
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1})\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}34{]} {[}68{]} {[}69{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Li-Sb\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
electrolysis of liquid antimony with melting salt; electrochemical
lithiation method\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
high volumetric capacity (Li\textsubscript{3}Sb:1890
mA\selectlanguage{ngerman}·h·cm\selectlanguage{english}\textsuperscript{-3}); working in high temperature
(\textgreater{} 350 degC)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
great volume expansion, poor reversibility; toxic; complex synthesis
method; moderate gravimetric capacity (Li\textsubscript{3}Sb: 660
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1})\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
{[}43{]} {[}34{]} {[}68{]} {[}69{]} {[}71{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li-Na\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
fusion reaction method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
not sacrifice the specific capacity because Li and Na metals exhibit
similar reaction activities; good electrostatic shield effect\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
great volume expansion; high reactivity in electrolyte;\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}73{]} {[}74{]} {[}85{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li-Mg\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
fusion reaction method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
high Li-ion diffusion coefficient; high gravimetric capacity (2690
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1} for the Mg-70 wt\% Li alloy); lighter; zero
overpotential\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
covered with an oxide layer resulting in poor Li kinetic behaviors\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}75{]} {[}76{]} {[}77{]} {[}78{]} {[}79{]} {[}80{]} {[}84{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li-Zn\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
electrochemical deposition method; fusion reaction method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
smaller volume expansion; good lithiophilic property to adjust even Li
deposition; eliminating nucleation barriers\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
low gravimetric capacity (355 mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1});\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}81{]} {[}82{]} {[}83{]} {[}84{]} {[}98{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li-Au\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
electrochemical lithiation method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
less structure change; zero overpotential; eliminating the nucleation
barriers\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
high cost\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}84{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li-Ag\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
electrochemical lithiation method; fusion reaction method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
less structure change; zero overpotential; eliminating the nucleation
barriers\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
high cost\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}99{]} {[}83{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li\emph{\textsubscript{x}}CuP\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
fusion reaction method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
good cycling stability\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
low gravimetric capacity (Li\textsubscript{0.25}CuP : 430
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1}); complex synthesize
method:\begin{CJK}{UTF8}{gbsn}　\end{CJK}\selectlanguage{english}N\textsubscript{2} flow at 780 \selectlanguage{ngerman}°C for 5 days\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}96{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li\textsubscript{4.4}Ge\emph{\textsubscript{x}}Si\textsubscript{1-\emph{x}}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
ball-milling method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Increasing lithium ions accommodation in the alloy, good
charge--discharge reversibility\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
low gravimetric capacity
(Li\textsubscript{4.4}Ge\textsubscript{0.67}Si\textsubscript{0.33}: 190
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1})\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}88{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Li-Cu-Sb\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
ball milling method, electrochemical lithiation method\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
good cycling stability; good electronic conductivity\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
low gravimetric capacity (Li\textsubscript{2}CuSb: 290
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1})\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
{[}87{]} {[}36{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
LiAl\textsubscript{1-\emph{x}}Zn\emph{\textsubscript{x}}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
fusion reaction method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
high theoretical capacities\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
complex synthesize condition: Ar atmosphere and very high temperature
(900 \selectlanguage{ngerman}°C)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}95{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li\textsubscript{2}MgSi\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
ball-milling + annealing method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
prevent the dissociation of Li-Mg alloy; reduce the stress/strain during
delithiation/lithiation; high capacity (807.8
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1})\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
complex synthesize method: Ar atmosphere, vacuum reaction at high
temperature; difficult to prepare high-purity\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}90{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li\emph{\textsubscript{x}}Cu\textsubscript{6}Sn\textsubscript{5}\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
electrochemical lithiation method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
small irreversible capacities; high volumetric capacity (1656
mA\selectlanguage{ngerman}·h·ml\selectlanguage{english}\textsuperscript{-1})\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
low gravimetric capacity
(Li\textsubscript{13}Cu\textsubscript{6}Sn\textsubscript{5}: 358
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1})\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}91{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li\emph{\textsubscript{x}}InSb\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
ball milling + electrochemical lithiation method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
good reversibility, stable during lithiation; very small volume
changes\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Low specific capacity (LiInSb, Li\textsubscript{2}InSb, and
Li\textsubscript{3}InSb, are 113, 227, and 340
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1})\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}97{]}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Li-B-Mg\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
fusion reaction method\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Porous structure; very negative potential close to pure lithium; good
strength and hardness, high capacity
(Li\textsubscript{2.6}BMg\textsubscript{0.05}: 1181.6
mA\selectlanguage{ngerman}·h·g\selectlanguage{english}\textsuperscript{-1})\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
complex synthesize method: Ar atmosphere, heating at high
temperature\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
{[}89{]} {[}93{]}\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}

To summary, table 1 has make conclusions about the various kinds of
binary and multi-component Li-containing alloys anodes as well as their
advantages and disadvantages. As can be seen, there are not perfect
lithium alloys used as the anodes. It is impossible to solve the problem
simply by replacing lithium metal with lithium alloys. Thus, combining
the lithium alloys with other materials, such as graphene, polymers,
etc., to overcome the weak links of lithium alloys have been proposed.

In order to solve some of the lithium alloys instability in air, Cui's
group developed densely packed Li\emph{\textsubscript{x}} M (M=Si, Sn,
or Al) nanoparticles encapsulated by large graphene sheets as shown in
Figure 3a{[}39{]}. With the protection of graphene sheets, the large and
freestanding Li\emph{\textsubscript{x}} M/graphene foils are stable in
different air conditions. Among the representative
Li\emph{\textsubscript{x}} Si/graphene foil maintained a stable
structure and cyclability in half cells (400 cycles with 98\% capacity
retention). And when paired with high-capacity Li-free
V\textsubscript{2}O\textsubscript{5} and sulfur cathodes, stable
full-cell cycling could also achieve. And the alloy electrodes have a
high reduction potential, leading to low energy density. To overcome
drastic volume variation during Li insertion/extraction cycles, except
to prepare superfine alloy particles that have small absolute volume
variation or constructing ternary alloy that contain an inactive metal
to inhibit the great volume expansion, but also can encapsulate the
lithium alloys in the flexible and elastic polymer matrix. For example,
Cui's group reported a polymer supported Li-Zn alloy structure as shown
in Figure 3b{[}100{]}. They used the ALD method to deposit the ZnO on
the polymide (PI) fiber. The core-shell PI-ZnO matrix was put into
contact with molten Li, ZnO reacted with molten Li to form Li-Zn alloy
and simultaneously extra Li can be drawn into the polymer matrix,
affording a Li-coated PI electrode. Thanks to the polymer shell, the
lithium alloys crack and pulverization can be alleviated.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image3/image3}

\end{center}
\end{figure}

\textbf{Figure 3} (a) Schematic of the microstructure and fabrication
process of the Li\emph{\textsubscript{x}} M/graphene foils. (Reproduced
from ref.{[}39{]}, with permission from Copyright \selectlanguage{ngerman}© 2017 Macmillan
Publishers Limited, part of Springer Nature.) (b) Schematic
representation of 3D Li-coated PI alloy electrode. (Reproduced from
ref.{[}100{]}, with permission from Copyright © 2016 Springer Nature.)

\subsection*{3.2 \textbar{} Lithium alloys matrix
Equations}

{\label{lithium-alloys-matrix-equations}}

By confining Li in a 3D structure, the infinite volume change during
cycling could be eliminated{[}101{]}. Furthermore, the high surface area
provided by 3D structures can further lower the localized current
density and enable a more stable plating/stripping process{[}26{]}. Even
confining the lithium metal in 3D carbon materials is a more common
strategy, there are still some pioneering works on using the 3D lithium
alloys matrix to host the lithium metal{[}26, 37, 102{]}.

In 2014, Zhang's group first employed a 3D lithium alloys
(Li\textsubscript{7}B\textsubscript{6}) fibrous matrix for ultra-stable
lithium-sulfur batteries{[}37{]}. The 3D nanostructured
Li\textsubscript{7}B\textsubscript{6} framework with high surface area
and enough volume space, could not only decrease the areal current
density, but also adequately accommodate the electrolyte and
re-deposited Li to stabilize the concentration of Li ions. By employing
this Li@Li\textsubscript{7}B6 anode, the Li-S batteries could stability
cycle to 2000 cycles. Recently, Yan and his co-workers reported a 3D Mg
doped LiB skeleton for hosting the metallic lithium and inhibiting the
lithium dendrite growth as shown in Figure 4a and 4b {[}102{]}. The 3D
LiB skeleton could significantly reduce volume variation during Li
electrochemical dissolution/deposition process. Its superior
lithiophilic and conductive characteristics could also contribute to the
reduction of the local current density and homogenization of incoming
Li\textsuperscript{+} flux. More importantly, Yan et al., used the
Density Functional Theory (DFT) calculation proved the doping of Mg
element to the 3D LiB skeleton could enhance the adsorption energy of
Li. And the remaining Li-deficient Li-Mg alloy forming after Li stripped
can help connect LiB fibers to stabilize the whole skeleton and lower
interfacial resistance, which could effectively inhibit the lithium
dendrite growth as shown in Figure 4c and 4d.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image4/image4}

\end{center}
\end{figure}

\textbf{Figure 4} The Li electrodissolution/electrodeposition process of
(a) Li-B-Mg composite and (b) pure Li foil. The SEM pictures of the
Li-B-Mg composite (c) and the pure Li foil (d) after cycling 100 cycles
under 2 mA\selectlanguage{ngerman}·cm\selectlanguage{english}\textsuperscript{-2}. (Reproduced from ref. {[}102{]}, with
permission from Copyright (c) 2020 The Authors. Published by WILEY-VCH.)

Additionally, constructing a 3D lithium alloy-based composites to
deposit lithium has been developed. For example, our group developed a
3D silver nanowire (AgNW) and graphene-based hierarchical host
(3D-AGBN){[}99{]}. Due to the Li ions will be favorably reduced on the
surface of AgNWs to form Li-Ag alloys and induce the Li depositing on
the AgNW as well as the high electrical conductivity of the continuous
AgNW nanonetwork can guarantee a fast and uniform electron
transportation throughout the entire 3D host with low overpotential.
Therefore, the Li deposition can be directed within the entire scaffold
(Figure 5a) to form a smooth Li layer covering the AgNW nanonetwork
after 1 mA*h*cm\selectlanguage{english}\textsuperscript{-2}plating as shown in Figure 5b and c.
Yang's group first synthesized a 3D metal-organic frameworks derived
carbon with abundant Zn clusters, after infusion the lithium, the high
active nano Zn clusters could react with lithium for form the Li-Zn
alloy as shown in Figure 5d{[}98{]}. Therefore, a 3D conductive carbon
supported Li-Zn alloy structure has realized, which enabled the
homogenization of the distributions of electric field and Li ion \selectlanguage{english}flux.
The Li-Zn alloy layer rendered the matrix to have good affinity with
lithium, and acted as a buffer layer for the following Li plating,
effectively eliminating nucleation barriers. And Zhang and his
co-workers proposed another kind of 3D carbon supported Li-Zn alloy
structure by infiltrating lithium into carbon cloth decorated with zinc
oxide arrays as shown in Figure 5e{[}103{]}. The XRD spectrum as shown
in Figure 4f confirmed the formation of LiZn alloy in Li-CC@ZnO. Such a
LiZn alloy formation in the Li plating process further induced
dendrite-free Li deposition. As a result, a low overpotential of
\textasciitilde{} 243 mV over 350 cycles at a high current density of 10
mA*cm\selectlanguage{english}\textsuperscript{-2} was achieved (shown in Figure 5f), compared to
the seriously fluctuated voltage and fast short circuit in the cell
using bare Li metal.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image5/image5}

\end{center}
\end{figure}

\textbf{Figure 5} (a) Schematic illustration of the Li plating in the
3D-AGBN host at a current density of 1 mA\selectlanguage{ngerman}·h·cm\selectlanguage{english}\textsuperscript{-2},
Magnified SEM images showing the AgNWs nanonetwork (b) before and (c)
after plating 1 mA*h*cm\selectlanguage{english}\textsuperscript{-2} of Li in the 3D-AGBN host.
(Reproduced from ref.{[}99{]}, with permission from Copyright (c) 2018
WILEY-VCH.) (d) Schematic representation exhibits the fabrication
process of Li-cMOFs. (Reproduced from ref.{[}98{]}, with permission from
Copyright (c) 2018 WILEY-VCH.) (e) Schematic fabrication process of
Li-CC@ZnO electrode, (f) XRD patterns of CC@ZnO electrode before and
after partial Li infiltration, and Li-CC@ZnO electrode. After Li
infiltration, the original diffraction peaks of ZnO disappear, instead,
(111) and (220) diffractions of Li-Zn alloy and (002) of
Li\textsubscript{2}O\textsubscript{2} appear. They are derived from the
reaction of molten Li with Zn. (g) Electrochemical performance
comparisons of the Li-CC@ZnO (red) and bare Li foil (black) symmetric
cells. Cyclic stabilities with a Li capacity of 10
mA*cm\selectlanguage{english}\textsuperscript{-2}. (Reproduced from ref.{[}103{]}, with
permission from Copyright (c) 2018 Tsinghua University Press and
Springer-Verlag GmbH Germany, part of Springer Nature.)

Except using the 3D alloy matrix to host metallic lithium, recently
researchers pay attention on various 3D Cu-alloys current collector.
After the 3D Cu current collector modified by active metals, such as
Al{[}104{]}, Sn{[}101{]}, Zn{[}105{]}, Au{[}25{]}, Ga-based liquid metal
alloys{[}106{]}, etc., it can form Li alloys after in-situ
electrochemically deposition Li and then served as seeds to induce the
formation of non-dendritic Li via lowering Li nucleation overpotential
and interfacial energy. For example, Guo's group reported a 3D Cu fibers
grown on the Cu foil coating with a thin Al layer{[}104{]}, forming a 3D
Cu@Al hybrid structure; after an initial discharge process above 0 V vs.
Li\textsuperscript{+}/Li, the thin Al layer reacted with Li to generate
a binary Li-Al alloy phase, which functioned as the lithiophilic sites.
The Li nucleation and growth promoted by Li-Al alloy layer realize a
dendrite-free Li anode as shown in Figure 6a and 6b. In addition, by
controlling the discharge process, the active Li stored in the form of
Li-Al alloy could act as a Li resource to compensate any irreversible Li
loss during cycling. D. Abruna et al., reported a Zn coated Cu foil
current collector{[}105{]}. During the Li plating process, the Li-Zn
alloy buffer layer on the Cu foil surface would regulate the nucleation
and growth of Li metal as shown in Figure 6c. As expectedly, the
Coulombic efficiencies of plating/stripping was enhanced and nucleation
overpotential was greatly reduced. And they also investigated the
electrochemical performances of high-energy-density Li-S full cells by
using the Zn coated Cu foils as Li metal current collectors. As shown in
Figure 6d, the cycling stability of these two kinds of batteries was
significantly enhanced.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image6/image6}

\end{center}
\end{figure}

\textbf{Figure 6} Schematic of the Li plating process on the (a) 3D Cu
foil and (b) 3D Cu@Al foil. (Reproduced from ref.{[}104{]}, with
permission from Copyright \selectlanguage{ngerman}© 2019 Wiley-VCH.) (c) Schematic illustration
of the proposed lithium nucleation and deposition processes on a bare Cu
foil (left) and a Zn modified Cu foil (right), (d) Cycling performance
of Li-S full cells tested at 0.2 C for the first 3 cycles and at 0.5 C
for the subsequent cycles with Li pre-deposited on a pristine Cu foil or
a Zn coated Cu foil as the anode. (Reproduced from ref.{[}105{]}, with
permission from Copyright © 2019 Tsinghua University Press and
Springer-Verlag GmbH Germany, part of Springer Nature.) (e) Schematic
illustration of the preparation process of PW@3D-Li, SEM images of (f)
Au-G/Cu foam, (g) 3D Li and (h) PW@3D-Li, Lower-left inserts in (f), (g)
and (h) represent optical photographs of Cu foam, 3D-Li and PW@3D-Li,
respectively. (Reproduced from ref.{[}25{]}, with permission from
Copyright © 2019 Elsevier B.V.)

Trapping Li into three-dimensional (3D) conductive host to construct
3D-Li is an effective strategy to suppress the growth of Li dendrites.
However, the increased contact area between 3D-Li and electrolyte
unavoidably induces more side reactions to further deteriorate the
electrochemical performance of lithium metal batteries. In order to keep
the advantages of 3D lithium-alloys matrix as well as reduce the side
effect, recently, Qu's group construct a paraffin wax (PW) coating
Au-graphene/Cu foam current collector{[}25{]}. Such a unique structure
was able to effectively avoid the growth of Li dendrites and formation
of ``dead Li'' during the Li plating process, which could be attributed
to these merits: i) Au could react with Li to form
Li\emph{\textsubscript{x}} Au alloys that lowered Li nucleation
overpotential and interfacial energy to effectively inhibit the
formation of dendritic Li; ii) 3D lithiophilic graphene decreased the
local current density and enabled the homogeneous growth of 3D Li; iii)
Cu skeleton not only afforded interconnected pores to accommodate the
volume variation of 3D-Li, but also served as a robust support to avoid
the collapse of overall electrode especially during fast
plating/stripping processes; iv) the PW protection layer confined Li
during the plating and stripping to mitigate the corrosion of
electrolyte and depress the formation of Li dendrites and ``dead Li''.

\subsection*{3.3 \textbar{} Artificial protective layers for lithium
alloys
anodes}

{\label{artificial-protective-layers-for-lithium-alloys-anodes}}

Even using the 3D matrix to host the Li-containing alloys,
unfortunately, these materials still suffer from poor SEI stability,
resulting in unsatisfied electrochemical performances{[}48{]}.
Therefore, constructing an artificial protective layer for lithium
alloys anodes has been proposed. For example, Cui's groups reported two
methods to construct artificial-SEI layer of LiF to protect
Li\emph{\textsubscript{x}} Si alloy nanoparticles via reducing
1-fluorodecane and fluoropolymer CYTOP, respectively{[}107, 108{]}. Ci
et al., reported a Li-O\textsubscript{2} coin cell with the
LiAl\emph{\textsubscript{x}} anode experienced a high-current
pretreatment{[}109{]}, as a result, the SEI film (including
Al\textsubscript{2}O\textsubscript{3}, LiF, ROCO\textsubscript{2}Li,
LiOH, and Li\textsubscript{2}CO\textsubscript{3}) formed after the
pretreatment process facilitated the uniform
Li\textsuperscript{+}shuttling during the following Li plating/stripping
process and stabilizes the LiAl\emph{\textsubscript{x}} anode interface
even after hundreds of cycles. The LiAl\emph{\textsubscript{x}}anode in
lithium oxygen batteries could increase cycling to 667 cycles under a
fixed capacity of 1000 mA·h·g\selectlanguage{english}\textsuperscript{-1} compared to 17 cycles
of LiAl\emph{\textsubscript{x}} anode without pre-treatment. Recently,
Zhang's group used a Li-Na alloy and 1,3-dioxolane (DOL) as anode and
additive, respectively, to control dendrite growth and buffer the volume
expansion of the alloy anode{[}85{]}. The 1,3-dioxolane additive could
in situ react with Li-Na alloy to form a robust and flexible passivation
film that suppress dendrite growth, buffer alloy anode volume expansion,
prevent cracking. As shown in Figure 7a-7d, only the Li-Na alloy
electrode with DOL additive existence can effectively suppress dendrite
growth and wouldn't crack after cycling.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image7/image7}

\end{center}
\end{figure}

\textbf{Figure 7} SEM images for (a, c) Li electrode and (b, d) Li-Na
alloy electrode with a Na/Li molar ratio of 6 after five
stripping/plating cycles in 0.5 M
NaCF\textsubscript{3}SO\textsubscript{3}/TEGDME or
NaCF\textsubscript{3}SO\textsubscript{3}/DOL/TEGDME electrolyte.
(Reproduced from ref.{[}85{]}, with permission from Copyright \selectlanguage{ngerman}© 2018 The
Author(s), under exclusive license to Springer Nature Limited.)

While a more common strategy to form an artificial SEI layer is using Li
salts to in-situ react with lithium alloys. It is easy to realize a thin
lithium alloy layers on the surface of Li metal by in situ reduction of
metal salts as shown in Eqns 1{[}110{]}:\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
\emph{x}Li+MA\emph{x} -M+LiA (M: metal, A: halogen) &
Eqns1\tabularnewline
\bottomrule
\end{longtable}

More importantly, the metal layer could immediately undergo reaction
with the underlying lithium to form the Li alloy as shown in Eqns
2{[}110{]}:\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
\emph{y}Li+\emph{z}M - Li\emph{y}M\emph{z} & Eqns2\tabularnewline
\bottomrule
\end{longtable}

For instance, in 2017, Nazar's group reported Li-rich composite alloy
films synthesized in situ on lithium by the above two
reactions{[}110{]}. Due to the lithium alloy and lithium salt composites
together form an artificial SEI layer to protect the lithium anode, it
can sustain electrodeposition over 700 cycles (1,400 h) of repeated
plating/stripping at a practical current density of 2
mA\selectlanguage{ngerman}·cm\selectlanguage{english}\textsuperscript{-2} and a 1,500 cycle-life was realized for a cell
paired with a
Li\textsubscript{4}Ti\textsubscript{5}O\textsubscript{12}positive
electrode. Following then, various lithium alloy-lithium salts
artificial SEI layers have been proposed, and Table 2 made a conclusion.
It can be observed that the metal halides are the most popular
candidates to react with lithium and form an inorganic composite
artificial SEI layers.

\textbf{Table 2} Various lithium alloy-lithium salts artificial SEI
layers.\selectlanguage{english}
\begin{longtable}[]{@{}lllll@{}}
\toprule
\textbf{Metal salts} & \textbf{Lithium Salts} & \textbf{Lithium alloys}
& \textbf{Artificial SEI layers} & \textbf{references}\tabularnewline
BiF\textsubscript{3} & LiF & Li-Bi & LiF/Li-Bi &
{[}111{]}\tabularnewline
InCl\textsubscript{3} & LiCl & Li-In & LiCl/Li-In &
{[}110{]}\tabularnewline
ZnCl\textsubscript{2} & LiCl & Li-Zn & LiCl/Li-Zn & {[}110{]}
{[}112{]}\tabularnewline
BiCl\textsubscript{3} & LiCl & Li-Bi & LiCl/Li-Bi &
{[}110{]}\tabularnewline
AsCl\textsubscript{3} & LiCl & Li-As & LiCl/Li-As &
{[}110{]}\tabularnewline
CaCl\textsubscript{2} & LiCl & Li-Ca & LiCl/Li-Ca &
{[}112{]}\tabularnewline
MgCl\textsubscript{2} & LiCl & Li-Mg & LiCl/Li-Mg &
{[}112{]}\tabularnewline
AlCl\textsubscript{3} & LiCl & Li-Al & LiCl/Li-Al & {[}112{]} {[}113{]}
{[}114{]}\tabularnewline
SiCl\textsubscript{4} & LiCl & Li-Si & LiCl/Li-Si &
{[}115{]}\tabularnewline
GeCl\textsubscript{4} & LiCl & Li-Ge & LiCl/Li-Ge &
{[}116{]}\tabularnewline
HAuCl\textsubscript{4} & LiCl & Li-Au & LiCl/Li-Au &
{[}117{]}\tabularnewline
AlI\textsubscript{3} & LiI & Li-Al & LiI/Li-Al &
{[}118{]}\tabularnewline
AgNO\textsubscript{3} & LiNO\textsubscript{3} & Li-Ag &
LiNO\textsubscript{3}/Li-Ag & {[}117{]}\tabularnewline
\bottomrule
\end{longtable}

However, these inorganic films are often thin, brittle, and vulnerable
to cracking due to the volume effect of the Li anode during extended
cycling{[}32{]}. Thus, a more flexible artificial SEI layers, such as
polymer-lithium alloy hybrid artificial SEI layers{[}119, 120{]}, has be
developed. For example, Xie et al reported a poly(tetramethylene ether
glycol) (PTMEG)-Li/Sn alloy hybrid layer on the Li metal
surface{[}119{]}. The possible mechanism for forming the artificial SEI
layer is shown in Figure 8a. Such a hybrid artificial layer not only
provided a fast lithium-ion transport path on account of the Li/Sn alloy
with ample Li vacancies, but also has a strong affinity for Li. Since
PTMEG is similar to poly(ethylene oxide) (PEO) with a large number of
C-O bonds. As a result, after only 20 cycles, many dendrites and dead Li
were observed for the pristine Li, whereas the treated Li presents a
smooth and compact deposition of Li\textsuperscript{+} as shown in
Figure 8b and 8c.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image8/image8}

\end{center}
\end{figure}

\textbf{Figure 8} (a) Possible reaction mechanism for the formation of
the PTMEG-Li/Sn alloy hybrid layer. SEM images of Li-Li symmetric cells
with (b) the pristine Li and (c) SnCl\textsubscript{4}+THF treated Li
after 20 cycles at 1 mA\selectlanguage{ngerman}·cm\selectlanguage{english}\textsuperscript{-2}, 1
mA*h*cm\selectlanguage{english}\textsuperscript{-2}. All scale bars are 20 \selectlanguage{greek}μ\selectlanguage{english}m. (Reproduced from
ref.{[}119{]}, with permission from Copyright \selectlanguage{ngerman}© 2019 Wiley-VCH.)

Moreover, researchers have also developed various kinds of
lithium-containing alloys artificial protective layers. The protective
lithium alloy layers are generally thin films formed on the Li metal
surface via chemical/electrochemical pre-treatment{[}85, 109-120{]},
mechanical press{[}121, 122{]}, magnetron sputtering{[}60{]}, etc.,
which are acceptable ionic conductivity for Li migration as well as
suppress the dendrite growth via homogenous deposition of
lithium{[}32{]}. For example, Li group reported a magnetron sputtering
method to deposit a thin Al film on lithium surface{[}60{]}. After
depositing, the Li-Al alloy layer would be formed on the lithium metal
surface and guide dense Li deposition. Mai's group reported an
artificial Li-Al interphase layer on Li-B alloy anode{[}121, 122{]}. The
Li-Al layer form in situ on the Li-B electrode via pressing Al foil with
Li-B foil discs under a pressure of 120 Mpa, then kept at this pressure
for several minutes or lithiated after 10 min. The artificial Li-Al
layer allowed electron and ion transport to Li-B electrode. The Li-Al
layer coating on Li-B electrode can improve cyclic life over 1200 h at a
current density of 0.2 mA·cm\selectlanguage{english}\textsuperscript{-2}, whereas bare Li-B
electrode has stable cycles not exceeding 800 h. In addition, when it
assembled with
LiMn\textsubscript{0.8}Fe\textsubscript{0.2}PO\textsubscript{4} cathode
and
Li\textsubscript{1.5}Al\textsubscript{0.5}Ge\textsubscript{1.5}(PO\textsubscript{4})\textsubscript{3}electrolyte,
the resulted solid state batteries could deliver an initial discharge
capacity of 153 mA*h*g\selectlanguage{english}\textsuperscript{-1} with good cyclic stability
and rate performance at 50 degC.

\textbf{3.4 \textbar{} LITHIUM ALLOYS MODIFIED ELECTROLYTES}

In the past decades, all-solid-state Li batteries received increasing
attentions due to nonflammability, dendrite blocking, and stability over
large potential windows{[}123{]}. But how to realize high safety, high
power density, and high energy density for all-solid-state Li batteries
is still a challenge. Recently, Hu's group creatively combined the
lithium alloy anode with garnet electrolyte to solve the problems of
all-solid-state Li batteries{[}123-126{]}. For example, in 2017, they
first proposed a new methodology for reducing the garnet/Li-metal
interfacial resistance by forming Li-Ge alloy. First a thin Ge layer (20
nm) was evaporated onto the garnet pellet by an electron beam
evaporation system, then put a small piece of Li metal disc on the
Ge-modified garnet, after heating, the Li-Ge alloy anode would be
formed. Because the effective contact area between Ge-modified-garnet
and Li-metal anode increased more than eight times compared to bare
garnet due to the alloying reaction between Li and Ge as shown in Figure
9a, the Li/Ge-modified garnet delivered a small interfacial resistance
of 115 \selectlanguage{greek}Ω\selectlanguage{ngerman}·cm\textsuperscript{2}, far smaller than the Li/bare garnet
(\selectlanguage{english}[?]900 \selectlanguage{greek}Ω\selectlanguage{ngerman}·cm\textsuperscript{2}). When it assembled with
LiFePO\textsubscript{4} to form an all-solid-state Li battery as shown
in Figure 9b, the cycling performance of this all-solid-state Li battery
has been improved significantly, even comparable with the full batteries
using the liquid electrolyte as shown in Figure 9c. Even the coulombic
efficiency was better than the full cells using liquid electrolyte in
Figure 9d.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image9/image9}

\end{center}
\end{figure}

\textbf{Figure 9} (a) Schematic representation for improving the contact
between garnet and Li metal by engineering the surface of the garnet
with a thin Ge layer. The Ge layer, evaporated onto garnet, can alloy
with Li metal, which leads to more continuous interfaces between the
garnet and Li metal and results in a small interfacial resistance. (b)
Schematic of the full cell structure, where a gel membrane was used
between garnet and LFP cathode. (c) Cycling performance of the
Li/Ge-modified-garnet/LFP cell and Li/liquid-electrolyte/LFP cell at 1
C. (d) Coulombic efficiencies of Li/Ge-modified-garnet/LFP cell and
Li/liquid-electrolyte/LFP cell at 1 C. (Reproduced from ref.{[}126{]},
with permission from Copyright \selectlanguage{ngerman}© 2017 Wiley-VCH.)

Since then, the Li-Zn, Li-Sn and Li-Mg alloy modified garnet solid
electrolytes have subsequently developed{[}123-125{]}. Such a facile
surface treatment on garnet electrolyte with forming lithium alloys
method offered a simple strategy to solve the interface problem in
solid-state lithium metal batteries.

\subsection*{3.5 \textbar{} Lithium Alloys modified
separators}

{\label{lithium-alloys-modified-separators}}

A multifunctional separator through coating a thin electronic conductive
film on one side of the conventional polymer separator facing the Li
anode could contribute to Li dendrite suppression and cycling stability
improvement{[}127{]}. Recently, Li and his co-workers developed a
multifunctional lithium alloys coating separator by reducing the
PbZr\textsubscript{0.52}Ti\textsubscript{0.48}O\textsubscript{3} (PZT)
coating layer on polypropylene (PP) separator{[}128{]}. The produced
Li-Pb alloy armor between the separator and Li anode, not only uniformed
the electric field across the interface but also mitigated the Li metal
nucleation, and therefore suppressed the dendrite growth during plating.
As a result, the Li/Li symmetric cells and LiFePO\textsubscript{4}/Li
cells with this such PZT-pretreated PP separators exhibit significantly
improved Coulombic efficiency and cycling life as shown in Figure 10a
and 10b.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image10/image10}

\end{center}
\end{figure}

\textbf{Figure 10} (a) Cycling behaviors of Li/Li symmetric cells
separated by PP,
Al\textsubscript{2}O\textsubscript{3}/PP/Al\textsubscript{2}O\textsubscript{3},
and PZT/PP/PZT at 2 mA\selectlanguage{ngerman}·cm\selectlanguage{english}\textsuperscript{-2} with an area capacity of 2
mA*h*cm\selectlanguage{english}\textsuperscript{-2}. (b) Cycling performance of LFP/Li cells
with PP, Al\textsubscript{2}O\textsubscript{3}/PP, or PZT/PP separator
and 1 M LiPF\textsubscript{6} in EC/DMC at 25 degC at 0.5 C{[}128{]}.
(Reproduced from ref.{[}128{]}, with permission from Copyright (c)
2019Wiley-VCH.)

\section*{Perspective on Li-containing alloys for high-safety and
high-energy density
batteries}

{\label{perspective-on-li-containing-alloys-for-high-safety-and-high-energy-density-batteries}}

The introduction of Li-containing alloys seems to be a fundamental tool
to resolve the safety hazards caused by lithium dendrites. But there are
still many unanswered questions, for instance, the protective mechanisms
for different alloys are not clearly understood{[}86{]}; the
Li-containing alloy materials can effectively improve the state of
first-layer Li deposition, however, the substrate will revert to pure Li
as deposition continues{[}54{]}; the Li-containing alloy anodes still
face the great volume change and serious side reaction during the
striping/plating process, etc. Therefore, these scientific problems are
still urgently awaiting our solutions.

Simply using lithium metal alloy anode/lithium alloy artificial SEI film
or using lithium alloy to modify the current collector, separator and
electrolytes cannot fully solve the challenges faced by lithium anode.
Only by combining multiple strategies can the problems caused by lithium
anode be better or completely solved. Here we proposed several
suggestions (as shown in Figure 11) for the future research of
lithium-containing alloys employed in Li metal batteries:

i) As the binary Li-containing alloy either has the high reaction
activity (i.e Li-Na), or the great volume change (i.e. Li-Si, Li-Sn), or
the low energy density (i.e. Li-Bi, Li-Zn), or the high cost (i.e.
Li-Ag, Li-Cu) each kind of shortcoming, it can take more consideration
into ternary/multicomponent lithium alloys, which can make up for each
other through multiple components. But the presence of additional metal
that are not directly involved in electrochemical reaction results in
additional weight and volume and thus cause the specific energy density
reducing compared to using the pure lithium or binary lithium alloy
anodes{[}129{]}. Another disadvantage is that there still exist a
substantial change in specific volume upon charging and discharging
alloy electrode reactants, can lead to loss of electrical contact, and
thus capacity loss{[}129{]}. In addition, the complexity and cost of
preparing ternary/ multicomponent lithium alloys also need to be
considered

ii) Considering the substantial volume change exactly exists in
lithium-containing alloys anodes, constructing nanostructures to host
lithium alloy or preparing lithium alloy-based composites is also a good
choice{[}130, 131{]}. By encapsulating the lithium alloy into special
nanostructures, i.e. 3D graphene{[}132{]}, CNT{[}131{]}, etc., or using
polymers coating{[}25{]}, the volume change of lithium alloy has been
effectively eliminated, because of these nanostructured host or extra
components, Li-containing alloy anodes will be more stable in the
organic electrolyte and the lithium dendrite would also be effectively
inhibited.

iii) Constructing artificial protection/SEI layer on the lithium alloy
anode, i.e., recently Won II Cho et al., reported a Li-Al anode
protected by a Langmuir-Blodgett artificial SEI composed of
MoS\textsubscript{2}{[}133{]}. Such a MoS\textsubscript{2} artificial
SEI layer exhibited a combination of a high Li binding energy, molecular
smoothness, and low barrier to Li adatom diffusion, which favors
efficient binding of Li and transport away from the
electrode/electrolyte interface as well as favors stable and reversible
Li migration of the MoS\textsubscript{2} coating Li-Al anode. As a
result, the MoS\textsubscript{2} coating Li-Al alloy anode exhibited
high reversibility stable Li migration during recharge of the cells
compared to the Li-Al alloy anode without the MoS\textsubscript{2}
coating.

iv) Developing the suitable electrolytes and separators for
lithium-containing alloys anodes. Modification of electrolyte or
separators with lithium alloy will limit its application in lithium
metal batteries, as electrolyte components have significantly influences
on the electrochemical performances of electrodes, no matter anode or
cathode. For example, the absence of volatile or \selectlanguage{english}flammable compounds is
expected to make solid electrolytes safer than their liquid counterparts
at elevated temperatures{[}11{]}. Additives, can decompose, polymerize
or adsorb on the Li surface, modifying the physico-chemical properties
of the SEI and therefore regulating the current distribution during Li
deposition{[}19, 23, 134{]}. Solvents, i.e, the ionic liquid, shows an
exciting role in improving the low temperature performances of
batteries{[}135{]}. Lithium salts could not only benefit to stabilize
the spontaneous solid electrolyte interphase (SEI) films, but also
control the nucleation and growth of metallic lithium, thus enhancing
the stabilities of lithium anodes during the stripping and plating
processes{[}21, 136{]}.

While separators serving as a physical barrier between electrodes,
traditional polyolefin-based separators easily suffer a ``shut-down''
problem when penetrate through lithium dendrites or exposed to
overheating and/or overcharge{[}11{]}. A suitable separator for
lithium-containing alloys anodes should have good thermal stability and
function to suppress the lithium dendrites. Additionally, a suitable
separator may also have the function to inhibit the polysulfides
shuttling for Li-S batteries and for Li-air batteries. Therefore, a
better strategy is combing the lithium alloys anodes with various
functional electrolytes and separators rather than use it to modify the
electrolyte or separators.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image11/image11}

\end{center}
\end{figure}

\textbf{Figure 11} The potential solving strategies towards the future
high-safety and high-energy-density metal batteries based on the lithium
alloys anodes.

Finally, we want to emphasize that more efforts should be devoted to
develop the Li-containing alloys anodes suitable for Li-S batteries and
Li-air batteries, as firstly, the energy density of LIBs is limited,
which could not meet the future electric vehicles and grid energy
storage markets; secondly as the higher reduction of polysulfide anions
in Li-S batteries and higher oxidation of superoxide radical anions in
Li-air batteries, some of Li-containing alloy anodes may be used stably
in LIBs but not stable in Li-S and Li-air batteries. Therefore, Li metal
protection in Li-S and Li-air batteries is more complicated compared
with lower energy density LIBs. In a word, we believe that through our
unremitting efforts, the Li-containing alloys anodes will show great
potentials in the high-safety and high-energy-density battery systems.

\textbf{ACKNOWLEDGEMENTS}

This work is financially supported by the National Natural Science
Foundation of China (No. 51871113 and 51902036), Natural Science
Foundation of Chongqing Science \& Technology Commission (No.
cstc2019jcyj-msxm1407), Natural Science Foundation of Chongqing
Technology and Business University (No. 1952009), the Key Research and
Development Program of Xuzhou (KC17004), the Science and Technology
Research Program of Chongqing Education Commission (No. KJQN201900826
and KJQN201800808), the Venture \& Innovation Support Program for
Chongqing Overseas Returnees (Grant No. CX2018129) and the Innovation
Group of New Technologies for Industrial Pollution Control of Chongqing
Education Commission (Grant No. CXQT19023).

\textbf{CONFLICT OF INTEREST}

The authors declare no potential conflict of interest.

\textbf{AUTHORSHIP AND CONTRIBUTORSHIP}

Dr. X. Gu and Dr. C. Lai conceive the idea; all authors contribute to
writing this review.

\textbf{REFERENCES}

{[}1{]} M. S. Whittingham, ``Electrical energy storage and intercalation
chemistry,'' \emph{Science,} vol. 192, no. 4244, pp. 1126-1127, 1976.
DOI: https://doi.org/10.1126/science.192.4244.1126.

{[}2{]} D. Lin, Y. Liu and Y. Cui, ``Reviving the lithium metal anode
for high-energy batteries,'' \emph{Nature Nanotechnology,} vol. 12, no.
3, pp. 194-206, 2017. DOI: https://doi.org/ 10.1038/nnano.2017.16.

{[}3{]} K. Brandt, ``Historical development of secondary lithium
batteries,'' \emph{Solid State Ionics,} vol. 69, no. 3-4, pp. 173-183,
1994. DOI: https://doi.org/10.1016/0167-2738(94)90408-1.

{[}4{]} Y. Guo, H. Li and T. Zhai, ``Reviving lithium-metal anodes for
next-generation high-energy batteries,'' \emph{Advanced Materials,} vol.
29, no. 29, 1700007, 2017. DOI: https://doi.org/10.1002/adma.201700007.

{[}5{]} X.-B. Cheng, C.-Z. Zhao, Y.-X. Yao, H. Liu and Q. Zhang,
``Recent advances in energy chemistry between solid-state electrolyte
and safe lithium-metal anodes,'' \emph{Chem,} vol. 5, no. 1, pp. 74-96,
2019. DOI: https://doi.org/10.1016/j.chempr.2018.12.002.

{[}6{]} Y. Ji, S. Weng, X. Li, Q. Zhang, L. Gu, ``Atomic-scale
structural evolution of electrode materials in Li-ion batteries: a
review, '' \emph{Rare Metals,} vol.29, no. 3, pp. 205--217. DOI:
https://doi.org/10.1007/s12598-020-01369-6

{[}7{]} X. Gu, T. Tang, X. Liu and Y. Hou, ``Rechargeable metal
batteries based on selenium cathodes: Progress, challenges and
perspectives,'' \emph{Journal of Materials Chemistry A,} vol. 7, no. 19,
pp. 11566-11583, 2019. DOI: https://doi.org/10.1039/C8TA12537F.

{[}8{]} H. Yuan, H.-J. Peng, J.-Q. Huang and Q. Zhang, ``Sulfur redox
reactions at working interfaces in lithium-sulfur batteries: A
perspective,'' \emph{Advanced Materials Interfaces,} vol. 6, no. 4,
1802046, 2019. DOI: https://doi.org/10.1002/admi.201802046.

{[}9{]} H. Yuan, H.-J. Peng, J.-Q. Huang and Q. Zhang, ``Sulfur redox
reactions at working interfaces in lithium-sulfur batteries: A
perspective,'' \emph{Advanced Materials Interfaces,} vol. 6, no. 4,
1802046, 2019. DOI: https://doi.org/10.1002/admi.201802046.

{[}10{]} X.-B. Cheng, C. Yan, X.-Q. Zhang, H. Liu and Q. Zhang,
``Electronic and ionic channels in working interfaces of lithium metal
anodes,'' \emph{ACS Energy Letters,} vol. 3, no. 7, pp. 1564-1570, 2018.
DOI: https://doi.org/10.1021/acsenergylett.8b00526.

{[}11{]} M.-T. F. Rodrigues, G. Babu, H. Gullapalli, K. Kalaga, F. N.
Sayed, K. Kato, J. Joyner and P. M. Ajayan, ``A materials perspective on
Li-ion batteries at extreme temperatures,'' \emph{Nature Energy,} vol.
2, no. 8, pp. 1-14, 2017. DOI: https://doi.org/10.1038/nenergy.2017.108.

{[}12{]} K. Zhang, G.-H. Lee, M. Park, W. Li and Y.-M. Kang, ``Recent
developments of the lithium metal anode for rechargeable non-aqueous
batteries,'' \emph{Advanced Energy Materials,} vol. 6, no. 20, 1600811,
2016. DOI: https://doi.org/10.1002/aenm.201600811.

{[}13{]} X.-B. Cheng, R. Zhang, C. Z. Zhao, F. Wei, J. G. Zhang and Q.
Zhang, ``A review of solid electrolyte interphases on lithium metal
anode,'' \emph{Advanced Science} , vol. 3, no. 3, 1500213, 2016. DOI:
https://doi.org/10.1002/advs.201500213.

{[}14{]} F. Ding, W. Xu, G. L. Graff, J. Zhang, M. L. Sushko, X. Chen,
Y. Shao, M. H. Engelhard, Z. Nie, J. Xiao, X. Liu, P. V. Sushko, J. Liu
and J. G. Zhang, ``Dendrite-free lithium deposition via self-healing
electrostatic shield mechanism,'' \emph{Journal of the American Chemical
Society,} vol. 135, no. 11, pp. 4450-4456, 2013. DOI:
https://doi.org/10.1021/ja312241y.

{[}15{]} X. Gu and C. Lai, ``One dimensional nanostructures contribute
better Li-S and Li-Se batteries: Progress, challenges and
perspectives,''\emph{Energy Storage Materials,} vol. 23, pp. 190-224,
2019. DOI: https://doi.org/10.1016/j.ensm.2019.05.013.

{[}16{]} K. Pu, X. Zhang, Xi. Qu, J. Hu, H. Li, M. Gao, H. Pan, Y. Liu,
``Recently developed strategies to restrain dendrite growth of Li metal
anodes for rechargeable batteries,'' \emph{Rare Metal} s, vol. 39, no.
6, pp. 616-635, 2020. DOI: https://doi.org/10.1007/s12598-020-01432-2

{[}17{]} B. Li, Y. Wang and S. Yang, ``A material perspective of
rechargeable metallic lithium anodes,'' \emph{Advanced Energy
Materials,} vol. 8, no. 13, 1702296, 2018. DOI:
https://doi.org/10.1002/aenm.201702296.

{[}18{]} X. Gu, Z. Yang, S. Qiao, C. Shao X. Ren and J. Y, ``Exploiting
methylated amino resin as a multifunctional binder for high-performance
lithium--sulfur batteries'', \emph{Rare Metals} , 2020. DOI:
http://doi.org/10.1007/s12598-020-01409-1

{[}19{]} X.-Q. Zhang, X.-B. Cheng, X. Chen, C. Yan and Q. Zhang,
``Fluoroethylene carbonate additives to render uniform Li deposits in
lithium metal batteries,'' \emph{Advanced Functional Materials,} vol.
27, no. 10, 1605989, 2017. DOI: https://doi.org/10.1002/adfm.201605989.

{[}20{]} H. Yu, J. Zhao, L. Ben, Y. Zhan, Y. Wu and X. Huang,
``Dendrite-free lithium deposition with self-aligned columnar structure
in a carbonate-ether mixed electrolyte,'' \emph{ACS Energy Letters,}vol.
2, no. 6, pp. 1296-1302, 2017. DOI:
https://doi.org/10.1021/acsenergylett.7b00273.

{[}21{]} H. Wang, M. Matsui, H. Kuwata, H. Sonoki, Y. Matsuda, X. Shang,
Y. Takeda, O. Yamamoto and N. Imanishi, ``A reversible dendrite-free
high-areal-capacity lithium metal electrode,'' \emph{Nature
Communications,} vol. 8, no. 1, pp. 1-9, 2017. DOI:
https://doi.org/10.1038/ncomms15106.

{[}22{]} E. Markevich, G. Salitra, F. Chesneau, M. Schmidt and D.
Aurbach, ``Very stable lithium metal stripping-plating at a high rate
and high areal capacity in fluoroethylene carbonate-based organic
electrolyte solution,'' \emph{ACS Energy Letters,} vol. 2, no. 6, pp.
1321-1326, 2017. DOI: https://doi.org/10.1021/acsenergylett.7b00300.

{[}23{]} H. Dai, X. Gu, J. Dong, C. Wang, C. Lai and S. Sun,
``Stabilizing lithium metal anode by octaphenyl polyoxyethylene-lithium
complexation,'' \emph{Nature Communications,} vol. 11, no. 1, pp. 1-11,
2020. DOI: https://doi.org/10.1038/s41467-020-14505-8.

{[}24{]} J. J. Xu, Q. C. Liu, Y. Yu, J. Wang, J. M. Yan and X. B. Zhang,
``In situ construction of stable tissue-directed/reinforced bifunctional
separator/protection film on lithium anode for lithium-oxygen
batteries,'' \emph{Advanced Materials,} vol. 29, no. 24, 1606552, 2017.
DOI: https://doi.org/10.1002/adma.201606552.

{[}25{]} M. Ye, X. Jin, X. Nan, J. Gao and L. Qu, ``Paraffin wax
protecting 3D non-dendritic lithium for backside-plated lithium metal
anode,'' \emph{Energy Storage Materials,} vol. 24, pp. 153-159, 2020.
DOI: https://doi.org/10.1016/j.ensm.2019.08.024.

{[}26{]} K. R. Adair, M. Iqbal, C. Wang, Y. Zhao, M. N. Banis, R. Li, L.
Zhang, R. Yang, S. Lu and X. Sun, ``Towards high performance Li metal
batteries: Nanoscale surface modification of 3D metal hosts for
pre-stored Li metal anodes,'' \emph{Nano Energy,} vol. 54, pp. 375-382,
2018. DOI: https://doi.org/10.1016/j.nanoen.2018.10.002.

{[}27{]} R. Mukherjee, A. V. Thomas, D. Datta, E. Singh, J. Li, O.
Eksik, V. B. Shenoy and N. Koratkar, ``Defect-induced plating of lithium
metal within porous graphene networks,'' \emph{Nature
Communications,}vol. 5, no. 1, pp. 1-10, 2014. DOI:
https://doi.org/10.1038/ncomms4710.

{[}28{]} R. Zhang, N. W. Li, X. B. Cheng, Y. X. Yin, Q. Zhang and Y. G.
Guo, ``Advanced micro/nanostructures for lithium metal
anodes,''\emph{Advanced Science,} vol. 4, no. 3, 1600445, 2017. DOI:
https://doi.org/10.1002/advs.201600445.

{[}29{]} B. Liu, J.-G. Zhang and W. Xu, ``Advancing lithium metal
batteries,'' \emph{Joule} , vol. 2, no. 5, pp. 833-845, 2018. DOI:
https://doi.org/10.1016/j.joule.2018.03.008.

{[}30{]} H. Yang, C. Guo, A. Naveed, J. Lei, J. Yang, Y. Nuli and J.
Wang, ``Recent progress and perspective on lithium metal anode
protection,'' \emph{Energy Storage Materials,} vol. 14, pp. 199-221,
2018. DOI: https://doi.org/10.1016/j.ensm.2018.03.001.

{[}31{]} F. Wu, Y.-X. Yuan, X.-B. Cheng, Y. Bai, Y. Li, C. Wu and Q.
Zhang, ``Perspectives for restraining harsh lithium dendrite growth:
Towards robust lithium metal anodes,'' \emph{Energy Storage
Materials,}vol. 15, pp. 148-170, 2018. DOI:
https://doi.org/10.1016/j.ensm.2018.03.024.

{[}32{]} C. Yang, K. Fu, Y. Zhang, E. Hitz and L. Hu, ``Protected
lithium-metal anodes in batteries: From liquid to solid,''\emph{Advanced
Materials,} vol. 29, no. 36, 1701169, 2017. DOI:
https://doi.org/10.1002/adma.201701169.

{[}33{]} L. Wang, Z. Zhou, X. Yan, F. Hou, L. Wen, W. Luo, J. Liang and
S. X. Dou, ``Engineering of lithium-metal anodes towards a safe and
stable battery,'' \emph{Energy Storage Materials,} vol. 14, pp. 22-48,
2018. DOI: https://doi.org/10.1016/j.ensm.2018.02.014.

{[}34{]} C. M. Park, J. H. Kim, H. Kim and H. J. Sohn, ``Li-alloy based
anode materials for Li secondary batteries,'' \emph{Chemical Society
Reviews,} vol. 39, no. 8, pp. 3115-3141, 2010. DOI:
https://doi.org/10.1039/B919877F.

{[}35{]} R. A. Huggins, ``Alloy negative electrodes for lithium
batteries formed in-situ from oxides,'' \emph{Ionics,} vol. 3, no. 3-4,
pp. 245-255, 1997. DOI: https://doi.org/10.1007/BF02375624.

{[}36{]} S. Matsuno, M. Noji, T. Kashiwagi, M. Nakayama and M. Wakihara,
``Construction of the ternary phase diagram for the Li-Cu-Sb system as
the anode material for a lithium ion battery,'' \emph{Journal of
Physical Chemistry C,} vol. 111, no. 20, pp. 7548-7553, 2007. DOI:
https://doi.org/10.1021/jp070397u.

{[}37{]} L. M. L. Fransson, J. T. Vaughey, R. Benedek, K. Edstr\selectlanguage{ngerman}öm, J. O.
Thomas and M. M. Thackeray, ``Phase transitions in lithiated
Cu\textsubscript{2}Sb anodes for lithium batteries: an in situ X-ray
diffraction study,'' \emph{Electrochemistry Communications,} vol. 3, no.
7, pp. 317-323, 2001. DOI:
https://doi.org/10.1016/S1388-2481(01)00140-0.

{[}38{]} X.-B. Cheng, H.-J. Peng, J.-Q. Huang, F. Wei and Q. Zhang,
``Dendrite-free nanostructured anode: Entrapment of lithium in a 3d
fibrous matrix for ultra-stable lithium-sulfur batteries,''\emph{Small,}
vol. 10, no. 21, pp. 4257-4263, 2014. DOI:
https://doi.org/10.1002/smll.201401837.

{[}39{]} H. Liu, X.-B. Cheng, J.-Q. Huang, S. Kaskel, S. Chou, H. S.
Park and Q. Zhang, ``Alloy anodes for rechargeable alkali-metal
batteries: Progress and challenge,'' \emph{ACS Materials Letters,} vol.
1, no. 22, pp. 217-229, 2019. DOI:
https://doi.org/10.1021/acsmaterialslett.9b00118.

{[}40{]} J. Zhao, G. Zhou, K. Yan, J. Xie, Y. Li, L. Liao, Y. Jin, K.
Liu, P. C. Hsu, J. Wang, H. M. Cheng and Y. Cui, ``Air-stable and
freestanding lithium alloy/graphene foil as an alternative to lithium
metal anodes,'' \emph{Nature Nanotechnology,} vol. 12, no. 10, pp.
993-999, 2017. DOI: https://doi.org/10.1038/nnano.2017.129.

{[}41{]} A. N. Dey, ``Electrochemical alloying of lithium in organic
electrolytes,'' \emph{Journal of the Electrochemical Society,} vol. 118,
no. 10, pp. 1547-1549, 1971. DOI: https://doi.org/10.1149/1.2407783.

{[}42{]} J. Yang, M. Winter and J. O. Besenhard, ``Small particle size
multiphase Li-alloy anodes for lithium-ion batteries,'' \emph{Solid
State Ionics,} vol. 90, no. 1-4, pp. 281-287, 1996. DOI:
https://doi.org/10.1016/S0167-2738(96)00389-X.

{[}43{]} H. J. Bang, S. Kim and J. Prakash, ``Electrochemical
investigations of lithium-aluminum alloy anode in Li/polymer
cells,''\emph{Journal of Power Sources,} vol. 92, no. 1-2, pp. 45-49,
2001. DOI: https://doi.org/10.1016/S0378-7753(00)00522-X.

{[}44{]} T. Chen, W. Kong, P. Zhao, H. Lin, Y. Hu, R. Chen, W. Yan and
Z. Jin, ``Dendrite-free and stable lithium metal anodes enabled by an
antimony-based lithiophilic interphase,'' \emph{Chemistry of
Materials,}2019, vol. 31, no. 18, pp. 7565-7573. DOI:
https://doi.org/10.1021/acs.chemmater.9b02356.

{[}45{]} D. Wang, W. Zhang, W. Zheng, X. Cui, T. Rojo and Q. Zhang,
``Towards high-safe lithium metal anodes: suppressing lithium dendrites
via tuning surface energy,'' \emph{Advanced Science,} vol. 4, no. 1,
1600168, 2017. DOI: https://doi.org/10.1002/advs.201600168.

{[}46{]} J. Zhao, Z. Lu, N. Liu, H. W. Lee, M. T. McDowell and Y. Cui,
``Dry-air-stable lithium silicide-lithium oxide core-shell nanoparticles
as high-capacity prelithiation reagents,'' \emph{Nature
Communications,}vol. 5, 5088, 2014. DOI:
https://doi.org/10.1038/ncomms6088.

{[}47{]} W.-J. Kwak, H.-J. Shin, J. Reiter, N. Tsiouvaras, J. Hassoun,
S. Passerini, B. Scrosati and Y.-K. Sun, ``Understanding problems of
lithiated anodes in lithium oxygen full-cells,'' \emph{Journal of
Materials Chemistry A,} vol. 4, no. 27, pp. 10467-10471, 2016. DOI:
https://doi.org/10.1039/C6TA03013K.

{[}48{]} T. Zhang, M. Hong, J. Yang, Z. Xu, J. Wang, Y. Guo and C.
Liang, ``A high performance lithium-ion-sulfur battery with a
free-standing carbon matrix supported Li-rich alloy
anode,''\emph{Chemical Science,} vol. 9, no. 47, pp. 8829-8835, 2018.
DOI: https://doi.org/ 10.1039/C8SC02897D.

{[}49{]} Y. Gao, R. Yi, Y. C. Li, J. Song, S. Chen, Q. Huang, T. E.
Mallouk and D. Wang, ``General method of manipulating formation,
composition, and morphology of solid-electrolyte interphases for stable
Li-alloy anodes,'' \emph{Journal of the American Chemical Society,} vol.
139, no. 48, pp. 17359-17367, 2017. DOI:
https://doi.org/10.1021/jacs.7b07584.

{[}50{]} J. E. Cloud, Y. Wang, X. Li, T. S. Yoder, Y. Yang and Y. Yang,
``Lithium silicide nanocrystals: Synthesis, chemical stability, thermal
stability, and carbon encapsulation,'' \emph{Inorganic Chemistry,} vol.
53, no. 20, pp. 11289-11297, 2014. DOI:
https://doi.org/10.1021/ic501923s.

{[}51{]} H. Deng, F. Qiu, X. Li, H. Qin, S. Zhao, P. He and H. Zhou, ``A
Li-ion oxygen battery with Li-Si alloy anode prepared by a mechanical
method,'' \emph{Electrochemistry Communications,} vol. 78, pp. 11-15,
2017. DOI: https://doi.org/10.1016/j.elecom.2017.03.010.

{[}52{]} S. Iwamura, H. Nishihara, Y. Ono, H. Morito, H. Yamane, H.
Nara, T. Osaka and T. Kyotani, ``Li-rich Li-Si alloy as a
lithium-containing negative electrode material towards high energy
lithium-ion batteries,'' \emph{Scientific Reports,} vol. 5, 8085, 2015.
DOI: https://doi.org/10.1038/srep08085.

{[}53{]} M. Wu, J. Jin and Z. Wen, ``Influence of a surface modified Li
anode on the electrochemical performance of Li-S batteries,'' \emph{RSC
Advances,} vol. 6, no. 46, pp. 40270-40276, 2016. DOI:
https://doi.org/10.1039/C6RA05316E.

{[}54{]} M. Wan, S. Kang, L. Wang, H. W. Lee, G. W. Zheng, Y. Cui and Y.
Sun, ``Mechanical rolling formation of interpenetrated lithium
metal/lithium tin alloy foil for ultrahigh-rate battery
anode,''\emph{Nature Communications,} vol. 11, no. 1, pp. 829, 2020.
DOI: https://doi.org/10.1038/s41467-020-14550-3.

{[}55{]} Q. Xu, Y. Yang and H. Shao, ``Enhanced cycleability and
dendrite-free lithium deposition by addition of sodium ion in
electrolyte for lithium metal batteries,'' \emph{Electrochimica
Acta,}vol. 271, pp. 617-623, 2018. DOI:
https://doi.org/10.1016/j.electacta.2018.03.182.

{[}56{]} Z. Tu, S. Choudhury, M. J. Zachman, S. Wei, K. Zhang, L. F.
Kourkoutis and L. A. Archer, ``Fast ion transport at solid-solid
interfaces in hybrid battery anodes,'' \emph{Nature Energy,} vol. 3, no.
4, pp. 310-316, 2018. DOI: https://doi.org/10.1038/s41560-018-0096-1.

{[}57{]} Q. Xu, Y. Yang and H. Shao, ``Enhanced cycleability and
dendrite-free lithium deposition by adding potassium ion to the
electrolyte for lithium metal batteries,'' \emph{Electrochimica
Acta,}vol. 212, pp. 758-766, 2016. DOI:
https://doi.org/10.1016/j.electacta.2016.07.080.

{[}58{]} X. Fan, J. Shao, X. Xiao, X. Wang, S. Li, H. Ge and L. Chen,
``SnLi4.4 nanoparticles encapsulated in carbon matrix as high
performance anode material for lithium-ion batteries,'' \emph{Nano
Energy,} vol. 9, pp. 196-203, 2014. DOI:
https://doi.org/10.1016/j.nanoen.2014.07.020.

{[}59{]} A. H. Whitehead, J. M. Elliott and J. R. Owen, ``Nanostructured
tin for use as a negative electrode material in Li-ion
batteries,''\emph{Journal of Power Sources,} vol. 81-82, pp. 33-38,
1999. DOI: https://doi.org/10.1016/S0378-7753(99)00126-3.

{[}60{]} H. Qiu, T. Tang, M. Asif, W. Li, T. Zhang and Y. Hou, ``Stable
lithium metal anode enabled by lithium metal partial
alloying,''\emph{Nano Energy,} vol. 65, 103989, 2019. DOI:
https://doi.org/10.1016/j.nanoen.2019.103989.

{[}61{]} S. Qu, W. Jia, Y. Wang, C. Li, Z. Yao, K. Li, Y. Liu, W. Zou,
F. Zhou, Z. Wang and J. Li, ``Air-stable lithium metal anode with
sputtered aluminum coating layer for improved
performance,''\emph{Electrochimica Acta,} vol. 317, pp. 120-127, 2019.
DOI: https://doi.org/10.1016/j.electacta.2019.05.138.

{[}62{]} H. Kim, J. T. Lee, D.-C. Lee, M. Oschatz, W. I. Cho, S. Kaskel
and G. Yushin, ``Enhancing performance of Li-S cells using a Li-Al alloy
anode coating,'' \emph{Electrochemistry Communications,} vol. 36, pp.
38-41, 2013. DOI: https://doi.org/10.1016/j.elecom.2013.09.002.

{[}63{]} J. Sun, Q. Zeng, R. Lv, W. Lv, Q.-H. Yang, R. Amal and D.-W.
Wang, ``A Li-ion sulfur full cell with ambient resistant Al-Li alloy
anode,'' \emph{Energy Storage Materials,} vol. 15, pp. 209-217, 2018.
DOI: https://doi.org/10.1016/j.ensm.2018.04.003.

{[}64{]} N. Kumagai, Y. Kikuchi and K. Tanno, ``Electrochemical
investigation of the diffusion of lithium in \selectlanguage{greek}\emph{β} -\selectlanguage{english}LiAl alloy at
room temperature,'' \emph{Journal of Applied Electrochemistry,} vol. 22,
no. 8, pp. 728-732, 1992. DOI: https://doi.org/10.1007/BF01027501.

{[}65{]} B. Duan, W. Wang, H. Zhao, A. Wang, M. Wang, K. Yuan, Z. Yu and
Y. Yang, ``Li-B Alloy as Anode Material for Lithium/Sulfur
Battery,''\emph{ECS Electrochemistry Letters,} vol. 2, no. 6, pp.
A47-A51, 2013. DOI: https://doi.org/10.1149/2.005306eel.

{[}66{]} X. Zhang, W. Wang, A. Wang, Y. Huang, K. Yuan, Z. Yu, J. Qiu
and Y. Yang, ``Improved cycle stability and high security of Li-B alloy
anode for lithium-sulfur battery,'' \emph{Journal of Materials Chemistry
A,} vol. 2, no. 30, pp. 11660-11665, 2014. DOI:
https://doi.org/10.1039/C4TA01709A.

{[}67{]} S. Choudhury, Z. Tu, S. Stalin, D. Vu, K. Fawole, D. Gunceler,
R. Sundararaman and L. A. Archer, ``Electroless formation of hybrid
lithium anodes for fast interfacial ion transport,'' \emph{Angewandte
Chemie International Edition,} vol. 56, no. 42, pp. 13070-13077, 2017.
DOI: https://doi.org/10.1002/anie.201707754.

{[}68{]} A. L. Santhosha, L. Medenbach, J. R. Buchheim and P. Adelhelm,
``The indium-lithium electrode in solid-state lithium-ion batteries:
Phase formation, redox potentials, and interface
stability,''\emph{Batteries \& Supercaps,} vol. 2, no. 6, pp. 524-529,
2019. DOI: https://doi.org/10.1002/batt.201800149.

{[}69{]} W. Weppner and R. A. Huggin, ``Thermodynamic properties of the
intermetallic systems lithium-antimony and
lithium-bismuth,''\emph{Journal of the Electrochemical Society,} vol.
125, no. 1, pp. 7-14, 1978. DOI: https://doi.org/10.1149/1.2131401.

{[}70{]} J. O. Besenhard and H. P. Fritz, ``Reversibles
elektrochemisches legieren von metallen der V. hauptgruppe in
organischen Li+-L\selectlanguage{ngerman}ösungen,'' \emph{Electrochimica Acta,} vol. 20, no.
6-7, pp. 513-517, 1975. DOI:
https://doi.org/10.1016/0013-4686(75)90042-0.

{[}71{]} W. Xianming, T. Nishina and I. Uchida, ``Lithium alloy
formation at bismuth thin layer electrode and its kinetics in propylene
carbonate electrolyte,'' \emph{Journal of Power Sources,} vol. 104, no.
1, pp. 90-96, 2002. DOI: https://doi.org/10.1016/S0378-7753(01)00876-X.

{[}72{]} A. G. Morachevskii, ``Lithium-antimony alloys: Phase diagram,
thermodynamic properties, electrochemical behavior in molten and
nonaqueous electrolytes, and use in lithium-ion
batteries,''\emph{Russian Journal of Applied Chemistry,} vol. 88, no.
11, pp. 1737-1749, 2016. DOI:
https://doi.org/10.1134/S10704272150110014.

{[}73{]} R. A. Huggins, ``Lithium alloy negative
electrodes,''\emph{Journal of Power Sources,} vol. 81-82, pp. 13-19,
1999. DOI: https://doi.org/10.1016/S0378-7753(99)00124-X.

{[}74{]} J. K. Stark, Y. Ding and P. A. Kohl, ``Dendrite-free
electrodeposition and reoxidation of lithium-sodium alloy for
metal-anode battery,'' \emph{Journal of the Electrochemical
Society,}vol. 158, no. 10, pp. A1100-A1105, 2011. DOI:
https://doi.org/10.1149/1.3622348.

{[}75{]} K. P. Doyle, C. M. Lang, K. Kim and P. A. Kohl, ``Dentrite-free
electrochemical deposition of Li-Na alloys from an ionic liquid
electrolyte,'' \emph{Journal of the Electrochemical Society,} vol. 153,
no. 7, pp. A1353-A1357, 2006. DOI: https://doi.org/10.1149/1.2199444.

{[}76{]} T. Krauskopf, B. Mogwitz, C. Rosenbach, W. G. Zeier and J.
Janek, ``Diffusion limitation of lithium metal and Li-Mg alloy anodes on
LLZO type solid electrolytes as a function of temperature and
pressure,'' \emph{Advances Energy Materials,} vol. 9, no. 44, 1902568,
2019. DOI: https://doi.org/10.1002/aenm.201902568.

{[}77{]} L. L. Kong, L. Wang, Z. C. Ni, S. Liu, G. R. Li and X. P. Gao,
``Lithium-magnesium alloy as a stable anode for lithium-sulfur
battery,'' \emph{Advances Functional Materials,} vol. 29, no. 13,
1808756, 2019. DOI: https://doi.org/10.1002/adfm.201808756.

{[}78{]} Y. Zhang, K. S. R. Chandran, M. Jagannathan, H. Z. Bilheux and
J. C. Bilheux, ``The nature of electrochemical delithiation of Li-Mg
alloy electrodes: neutron computed tomography and analytical modelling
of Li diffusion and delithiation phenomenon,'' \emph{Journal of The
Electrochemical Society,} vol. 164, no. 2, pp. A28-A38, 2017. DOI:
https://doi.org/10.1149/2.0051702jes.

{[}79{]} T. J. Richardson and G. Chen, ``Solid solution lithium alloy
cermet anodes,'' \emph{Journal of Power Sources,} vol. 174, no. 2, pp.
810-812, 2007. DOI: https://doi.org/10.1016/j.jpowsour.2007.06.106.

{[}80{]} Z. Shi, M. Liu, D. Naik and J. L. Gole, ``Electrochemical
properties of Li-Mg alloy electrodes for lithium
batteries,''\emph{Journal Power Sources,} vol. 92, no. 1-2, pp. 70-80,
2001. DOI: https://doi.org/10.1016/S0378-7753(00)00521-8.

{[}81{]} M. Jagannathan and K. S. R. Chandran, ``Electrochemical
charge/discharge behavior and phase transitions during cell cycling of
Li (Mg) alloy anodes for high capacity Li ion batteries,'' \emph{Journal
of The Electrochemical Society,} vol. 160, no. 10, pp. A1922-A1926,
2013. DOI: https://doi.org/10.1149/2.006311jes.

{[}82{]} J. Wang, P. King and R. A. Huggins, ``Investigations of binary
lithium-zinc, lithium-cadmium and lithium-lead alloys as negative
electrodes in organic solvent-based electrolyte,'' \emph{Solid State
Ionics,} vol. 20, no. 3, pp. 185-189, 1986. DOI:
https://doi.org/10.1016/0167-2738(86)90212-2.

{[}83{]} C. Chen, Y. Yang and H. Shao, ``Enhancement of the lithium
cycling capability using Li-Zn alloy substrate for lithium metal
batteries,'' \emph{Electrochimica Acta,} vol. 137, pp. 476-483, 2014.
DOI: https://doi.org/10.1016/j.electacta.2014.06.006.

{[}84{]} ``Inward-growth plating of lithium driven by solid-solution
based alloy phase for highly reversible lithium metal anode,'' ArXiv
Preprint ArXiv, October 2019. {[}Online{]}. Available:
https://arxiv.org/abs/1910.13159.

{[}85{]} K. Yan, Z. Lu, H.-W. Lee, F. Xiong, P.-C. Hsu, Y. Li, J. Zhao,
S. Chu and Y. Cui, ``Selective deposition and stable encapsulation of
lithium through heterogeneous seeded growth,'' \emph{Nature Energy,}vol.
1, no. 3, pp. 1-8, 2016. DOI: https://doi.org/10.1038/nenergy.2016.10.

{[}86{]} J. L. Ma, F. L. Meng, Y. Yu, D. P. Liu, J. M. Yan, Y. Zhang, X.
B. Zhang and Q. Jiang, ``Prevention of dendrite growth and volume
expansion to give high-performance aprotic bimetallic Li-Na
alloy-O\textsubscript{2} batteries,'' \emph{Nature chemistry,} vol. 11,
no. 1, pp. 64-70, 2019. DOI: https://doi.org/10.1038/s41557-018-0166-9.

{[}87{]} Y. Xu, S. Zhao, G. Zhou, W. Chen, F. Zhou, Z. Rong, Y. Wu, J.
Li, J. Guo and Y. Zhang, ``Solubility-dependent protective effects of
binary alloys for lithium anode,'' \emph{ACS Applied Energy
Materials,}vol. 3, no. 3, pp. 2278-2284, 2020. DOI:
https://doi.org/10.1021/acsaem.9b02125.

{[}88{]} Y. Hashimoto, ``Preparation of
Li\textsubscript{4.4}Ge\emph{\textsubscript{x}}
Si\emph{\textsubscript{1-x}}alloys by mechanical milling process and
their properties as anode materials in all-solid-state lithium
batteries,'' \emph{Solid State Ionics,} vol. 175, no. 1-4, pp. 177-180,
2004. DOI: https://doi.org/10.1016/j.ssi.2004.08.022.

{[}89{]} S. Liu, J. Yang, L. Yin, Z. Li, J. Wang and Y. Nuli,
``Lithium-rich Li\textsubscript{2.6}BMg\textsubscript{0.05} alloy as an
alternative anode to metallic lithium for rechargeable lithium
batteries,'' \emph{Electrochimica Acta,} vol. 56, no. 24, pp. 8900-8905,
2011. DOI: https://doi.org/10.1016/j.electacta.2011.07.109.

{[}90{]} Y. Liu, R. Ma, Y. He, M. Gao and H. Pan, ``Synthesis, structure
transformation, and electrochemical properties of
Li\textsubscript{2}MgSi as a novel anode for Li-ion
batteries,''\emph{Advanced Functional Materials,} vol. 24, no. 25, pp.
3944-3952, 2014. DOI: https://doi.org/10.1002/adfm.201304287.

{[}91{]} K. D. Kepler, J. T. Vaughey and M. M. Thackeray,
``Li\emph{\textsubscript{x}}
Cu\textsubscript{6}Sn\textsubscript{5}(0\textless{}\emph{x}
\textless{}13): An intermetallic insertion electrode for rechargeable
lithium batteries,'' \emph{Electrochemical and Solid-State Letters,}
vol. 2, no. 7, pp. 307-309, 1999. DOI:
https://doi.org/10.1149/1.1390819.

{[}92{]} H. Li, L. Shi, Q. Wang, L. Chen and X. Huang, ``Nano-alloy
anode for lithium ion batteries,'' \emph{Solid State Ionics,} vol. 148,
no. 3-4, pp. 247-258, 2002. DOI:
https://doi.org/10.1016/S0167-2738(02)00061-9.

{[}93{]} Y. Gui, Z. Liu, L. Chen, H. Huang and H. Ning, ``Effect of Mg
on the skeleton structure and properties of Li-B alloy for lithium
secondary battery,'' \emph{Journal of Functional Materials,} vol. 50,
no. 9, pp. 09027-09032, 2019. DOI:
https://doi.org/10.3969/j.issn.1001-9731.2019.09.005.

{[}94{]} S. Liu, X. Zhang, R. Li, L. Gao and J. Luo, ``Dendrite-free Li
metal anode by lowering deposition interface energy with
Cu\textsubscript{99}Zn alloy coating,'' \emph{Energy Storage
Materials,}vol. 14, pp. 143-148, 2018. DOI:
https://doi.org/10.1016/j.ensm.2018.03.004.

{[}95{]} I. Chumak, G. Dmytriv, V. Pavlyuk, S. Oswald, J. Eckert, H.
Trill, H. Eckert, H. Pauly and H. Ehrenberg, ``\selectlanguage{greek}β-\selectlanguage{english}Li\textsubscript{2}Zn5:
a low symmetric polar intermetallic compound,'' \emph{Journal of
Materials Research,} vol. 25, no. 19, pp. 1492-1499, 2011. DOI:
https://doi.org/10.1021/acs.inorgchem.9b01266.

{[}96{]} O. Crosnier, C. Mounsey, P. S. Herle, N. Taylor and L. F.
Nazar, ``Crystal structure and electrochemical behavior of
Li\textsubscript{2}CuP:  A surprising reversible crystalline-amorphous
transformation,'' \emph{Chemistry of Materials,} vol. 15, no. 26, pp.
4890-4892, 2003. DOI: https://doi.org/10.1021/cm034619m.

{[}97{]} J. T. Vaughey, J. O. Hara and M. M. Thackeray, ``Intermetallic
insertion electrodes with a zinc blende-type structure for Li batteries:
A study of Li\emph{\textsubscript{x}} InSb (0[?]\emph{x}
[?]3),''\emph{Electrochemical and Solid-State Letters,} vol. 3, no. 1, pp.
13-16, 2000. DOI: https://doi.org/10.1149/1.1390944.

{[}98{]} M. Zhu, B. Li, S. Li, Z. Du, Y. Gong and S. Yang,
``Dendrite-free metallic lithium in lithiophilic carbonized
metal-organic frameworks,'' \emph{Advanced Energy Materials,} vol. 8,
no. 18, 1703505, 2018. DOI: https://doi.org/10.1002/aenm.201703505.

{[}99{]} P. Xue, S. Liu, X. Shi, C. Sun, C. Lai, Y. Zhou, D. Sui, Y.
Chen and J. Liang, ``A hierarchical silver-nanowire-graphene host
enabling ultrahigh rates and superior long-term cycling of lithium-metal
composite anodes,'' \emph{Advanced Materials,} vol. 30, no. 44, 1804165,
2018. DOI: https://doi.org/10.1002/adma.201804165.

{[}100{]} Y. Liu, D. Lin, Z. Liang, J. Zhao, K. Yan and Y. Cui,
``Lithium-coated polymeric matrix as a minimum volume-change and
dendrite-free lithium metal anode,'' \emph{Nature Communications,} vol.
7, 10992, 2016. DOI: https://doi.org/10.1038/ncomms10992.

{[}101{]} Z. Luo, C. Liu, Y. Tian, Y. Zhang, Y. Jiang, J. Hu, H. Hou, G.
Zou and X. Ji, ``Dendrite-free lithium metal anode with lithiophilic
interphase from hierarchical frameworks by tuned
nucleation,''\emph{Energy Storage Materials,} vol. 27, pp. 124-132,
2020. DOI: https://doi.org/10.1016/j.ensm.2020.01.025.

{[}102{]} C. Wu, H. Huang, W. Lu, Z. Wei, X. Ni, F. Sun, P. Qing, Z.
Liu, J. Ma, W. Wei, L. Chen, C. Yan and L. Mai, ``Mg doped Li-LiB alloy
with in situ formed lithiophilic LiB skeleton for lithium metal
batteries,'' \emph{Advanced Science,} vol. 7, 1902643, 2020. DOI:
https://doi.org/10.1002/advs.201902643.

{[}103{]} X. Wang, Z. Pan, Y. Wu, X. Ding, X. Hong, G. Xu, M. Liu, Y.
Zhang and W. Li, ``Infiltrating lithium into carbon cloth decorated with
zinc oxide arrays for dendrite-free lithium metal anode,'' \emph{Nano
Research,} vol. 12, no. 3, pp. 525-529, 2018. DOI:
https://doi.org/10.1007/s12274-018-2245-z.

{[}104{]} H. Ye, Z. J. Zheng, H. R. Yao, S. C. Liu, T. T. Zuo, X. W. Wu,
Y. X. Yin, N. W. Li, J. J. Gu, F. F. Cao and Y. G. Guo, ``Guiding
uniform Li plating/stripping through lithium-aluminum alloying medium
for long-life Li metal batteries,'' \emph{Angewandte Chemie
International Edition,} vol. 58, no. 4, pp. 1094-1099, 2019. DOI:
https://doi.org/10.1002/ange.201811955.

{[}105{]} N. Zhang, S.-H. Yu and H. D. Abru\selectlanguage{ngerman}ña, ``Regulating lithium
nucleation and growth by zinc modified current collectors,'' \emph{Nano
Research,} vol. 13, no. 1, pp. 45-51, 2019. DOI:
https://doi.org/10.1007/s12274-019-2567-7.

{[}106{]} C. Wei, H. Fei, Y. An, Y. Tao, J. Feng and Y. Qian, ``Uniform
Li deposition by regulating the initial nucleation barrier via a simple
liquid-metal coating for a dendrite-free Li-metal anode,'' \emph{Journal
of Materials Chemistry A,} vol. 7, no. 32, pp. 18861-18870, 2019. DOI:
https://doi.org/10.1039/C9TA06663B.

{[}107{]} J. Zhao, Z. Lu, H. Wang, W. Liu, H. W. Lee, K. Yan, D. Zhuo,
D. Lin, N. Liu and Y. Cui, ``Artificial solid electrolyte
interphase-protected Li\emph{\textsubscript{x}} Si nanoparticles: An
efficient and stable prelithiation reagent for lithium-ion
batteries,''\emph{Journal of the American Chemical Society,} vol. 137,
no. 26, pp. 8372-8375, 2015. DOI: https://doi.org/10.1021/jacs.5b04526.

{[}108{]} J. Zhao, L. Liao, F. Shi, T. Lei, G. Chen, A. Pei, J. Sun, K.
Yan, G. Zhou, J. Xie, C. Liu, Y. Li, Z. Liang, Z. Bao and Y. Cui,
``Surface fluorination of reactive battery anode materials for enhanced
stability,'' \emph{Journal of the American Chemical Society,} vol. 139,
no. 33, pp. 11550-11558, 2017. DOI:
https://doi.org/10.1021/jacs.7b05251.

{[}109{]} H. Guo, G. Hou, D. Li, Q. Sun, Q. Ai, P. Si, G. Min, J. Lou,
J. Feng and L. Ci, ``High current enabled stable lithium anode for
ultralong cycling life of lithium-oxygen batteries,'' \emph{ACS Applied
Materials \& Interfaces,} vol. 11, no. 34, pp. 30793-30800, 2019. DOI:
https://doi.org/10.1021/acsami.9b08153.

{[}110{]} X. Liang, Q. Pang, I. R. Kochetkov, M. S. Sempere, H. Huang,
X. Sun and L. F. Nazar, ``A facile surface chemistry route to a
stabilized lithium metal anode,'' \emph{Nature Energy} , vol. 2, no. 9,
17119, 2017. DOI: https://doi.org/10.1038/nenergy.2017.119.

{[}111{]} Y. X. Ren, L. Zeng, H. R. Jiang, W. Q. Ruan, Q. Chen and T. S.
Zhao, ``Rational design of spontaneous reactions for protecting porous
lithium electrodes in lithium-sulfur batteries,'' \emph{Nature
Communications,} vol. 10, no. 1, pp. 1-10, 2019. DOI:
https://doi.org/10.1038/s41467-019-11168-y.

{[}112{]} F. Li, Y. H. Tan, Y. C. Yin, T. W. Zhang, L. L. Lu, Y. H.
Song, T. Tian, B. Shen, Z. X. Zhu and H. B. Yao, ``A fluorinated
alloy-type interfacial layer enabled by metal fluoride nanoparticle
modification for stabilizing Li metal anodes,'' \emph{Chemical
Science,}vol. 10, no. 42, pp. 9735-9739, 2019. DOI:
https://doi.org/10.1039/C9SC01845J.

{[}113{]} Y. Liu, X. Xu, X. Jiao, L. Guo, Z. Song, S. Xiong and J. Song,
``LixGe containing ion-conductive hybrid skin for high rate lithium
metal anode,'' \emph{Chemical Engineering Journal,} vol. 371, pp.
294-300, 2019. DOI: https://doi.org/10.1016/j.cej.2019.04.068.

{[}114{]} B. Xu, Z. Liu, J. Li, X. Huang, B. Qie, T. Gong, L. Tan, X.
Yang, D. Paley, M. Dontigny, K. Zaghib, X. Liao, Q. Cheng, H. Zhai, X.
Chen, L.-Q. Chen, C.-W. Nan, Y.-H. Lin and Y. Yang, ``Engineering
interfacial adhesion for high-performance lithium metal
anode,''\emph{Nano Energy,} vol. 67, 104242, 2020. DOI:
https://doi.org/10.1016/j.nanoen.2019.104242.

{[}115{]} G. Hou, C. Ci, D. Salpekar, Q. Ai, Q. Chen, H. Guo, L. Chen,
X. Zhang, J. Cheng, K. Kato, R. Vajtai, P. Si, G. Babu, L. Ci and P. M.
Ajayan, ``Stable lithium metal anode enabled by an artificial
multi-phase composite protective film,'' \emph{Journal of Power
Sources,} vol. 448, 227547, 2020. DOI:
https://doi.org/10.1016/j.jpowsour.2019.227547.

{[}116{]} K. Liao, S. Wu, X. Mu, Q. Lu, M. Han, P. He, Z. Shao and H.
Zhou, ``Developing a ``wate-defendable'' and ``dendrite-free''
lithium-metal anode using a simple and promising
GeCl\textsubscript{4}pretreatment method,'' \emph{Advanced Materials,}
vol. 30, no. 36, 1705711, 2018. DOI:
https://doi.org/10.1002/adma.201705711.

{[}117{]} F. Guo, C. Wu, H. Chen, F. Zhong, X. Ai, H. Yang and J. Qian,
``Dendrite-free lithium deposition by coating a lithiophilic
heterogeneous metal layer on lithium metal anode,'' \emph{Energy Storage
Materials,} vol. 24, pp. 635-643, 2020. DOI:
https://doi.org/10.1016/j.ensm.2019.06.010.

{[}118{]} L. Ma, M. S. Kim and L. A. Archer, ``Stable artificial solid
electrolyte interphases for lithium batteries,'' \emph{Chemistry of
Materials,} vol. 29, no. 10, pp. 4181-4189, 2017. DOI:
https://doi.org/10.1021/acs.chemmater.6b03687.

{[}119{]} Z. Jiang, L. Jin, Z. Han, W. Hu, Z. Zeng, Y. Sun and J. Xie,
``Facile generation of polymer-alloy hybrid layers for dendrite-free
lithium-metal anodes with improved moisture stability,''\emph{Angewandte
Chemie International Edition,} vol. 58, no. 33, pp. 11374-11378, 2019.
DOI: https://doi.org/10.1002/anie.201905712.

{[}120{]} ``Facile construction of a hybrid artificial protective layer
for stable lithium metal anode,'' \emph{Chemical Engineering Journal} ,
pp. 123542 2019. DOI: https://doi.org/10.1016/j.cej.2019.123542.

{[}121{]} H. Zhong, L. Sang, F. Ding, J. Song and Y. Mai, ``Conformation
of lithium-aluminium alloy interphase-layer on lithium metal anode used
for solid state batteries,'' \emph{Electrochimica Acta,} vol. 277, pp.
268-275, 2018. DOI: https://doi.org/10.1016/j.electacta.2018.04.191.

{[}122{]} H. Zhong, Y. Wu, F. Ding, L. Sang and Y. Mai, ``An artificial
Li-Al interphase layer on Li-B alloy for stable lithium-metal
anode,''\emph{Electrochimica Acta,} vol. 304, pp. 255-262, 2019. DOI:
https://doi.org/10.1016/j.electacta.2019.03.009.

{[}123{]} C. Wang, Y. Gong, B. Liu, K. Fu, Y. Yao, E. Hitz, Y. Li, J.
Dai, S. Xu, W. Luo, E. D. Wachsman and L. Hu, ``Conformal, nanoscale ZnO
surface modification of garnet-based solid-state electrolyte for lithium
metal anodes,'' \emph{Nano Letters,} vol. 17, no. 1, pp. 565-571, 2017.
DOI: https://doi.org/10.1021/acs.nanolett.6b04695.

{[}124{]} C. Yang, H. Xie, W. Ping, K. Fu, B. Liu, J. Rao, J. Dai, C.
Wang, G. Pastel and L. Hu, ``An electron/ion dual-conductive alloy
framework for high-rate and high-capacity solid-state lithium-metal
batteries,'' \emph{Advanced Materials,} vol. 31, no. 3, 1804815, 2019.
DOI: https://doi.org/10.1002/adma.201804815.

{[}125{]} C. Wang, H. Xie, L. Zhang, Y. Gong, G. Pastel, J. Dai, B. Liu,
E. D. Wachsman and L. Hu, ``Universal soldering of lithium and sodium
alloys on various substrates for batteries,'' \emph{Advanced Energy
Materials,} vol. 8, no. 6, 1701963, 2018. DOI:
https://doi.org/10.1002/aenm.201701963.

{[}126{]} W. Luo, Y. Gong, Y. Zhu, Y. Li, Y. Yao, Y. Zhang, K. K. Fu, G.
Pastel, C. F. Lin, Y. Mo, E. D. Wachsman and L. Hu, ``Reducing
interfacial resistance between garnet-structured solid-state electrolyte
and Li-metal anode by a germanium layer,'' \emph{Advanced
Materials,}vol. 29, no. 22, 1606042, 2017. DOI:
https://doi.org/10.1002/adma.201606042.

{[}127{]} H. Lee, X. Ren, C. Niu, L. Yu, M. H. Engelhard, I. Cho, M.-H.
Ryou, H. S. Jin, H.-T. Kim, J. Liu, W. Xu and J.-G. Zhang, ``Suppressing
lithium dendrite growth by metallic coating on a
separator,''\emph{Advanced Functional Materials,} vol. 27, no. 45,
1704391, 2017. DOI: https://doi.org/10.1002/adfm.201704391.

{[}128{]} Z. Hu, F. Liu, J. Gao, W. Zhou, H. Huo, J. Zhou and L. Li,
``Dendrite-free lithium plating induced by in situ transferring
protection layer from separator,'' \emph{Advanced Functional
Materials,}vol. 30, no. 5, 1907020, 2019. DOI:
https://doi.org/10.1002/adfm.201907020.

{[}129{]} J. O. Besenhard, P. Komenda, A. Paxinos and E. Wudy, ``Binary
and ternary Li-alloys as anode materials in rechargeable organic
electrolyte Li-batteries,'' \emph{Solid State lonics,} vol. 18-19, pp.
823-827, 1986. DOI: https://doi.org/10.1016/0167-2738(86)90270-5.

{[}130{]} F. Sun, D. Zhou, X. He, M. Osenberg, K. Dong, L. Chen, S. Mei,
A. Hilger, H. Markötter, Y. Lu, S. Dong, S. Marathe, C. Rau, X. Hou, J.
Li, M. C. Stan, M. Winter, R. Dominko and I. Manke, ``The morphological
reversibility of modified-Li based anode for next generation
batteries,'' \emph{ACS Energy Letters,} vol. 5, no. 1, pp. 152-161,
2019. DOI: https://doi.org/10.1021/acsenergylett.9b02424.

{[}131{]} S. Jiang, Y. Lu, Y. Lu, M. Han, H. Li, Z. Tao, Z. Niu and J.
Chen, ``Nafion/titanium dioxide-coated lithium anode for stable
lithium-sulfur batteries,'' \emph{Chemistry-An Asian Journal,} vol. 13,
no. 10, pp. 1379-1385, 2018. DOI:
https://doi.org/10.1002/asia.201800326.

{[}132{]} S. Matsuda, Y. Kubo, K. Uosaki and S. Nakanishi,
``Lithium-metal deposition/dissolution within internal space of CNT 3D
matrix results in prolonged cycle of lithium-metal negative
electrode,''\emph{Carbon,} vol. 119, pp. 119-123, 2017. DOI:
https://doi.org/10.1016/j.carbon.2017.04.032.

{[}133{]} M. S. Kim, Deepika, S. H. Lee, M.-S. Kim, J.-H. Ryu, K.-R.
Lee, L. A. Archer and W. I. Cho, ``Enabling reversible redox reactions
in electrochemical cells using protected LiAl intermetallics as lithium
metal anodes,'' \emph{Science Advances,} vol. 5, no. 10, eaax5587, 2019.
DOI: https://doi.org/10.1126/sciadv.aax5587.

{[}134{]} D. Lin, Y. Liu, A. Pei and Y. Cui, ``Nanoscale perspective:
Materials designs and understandings in lithium metal
anodes,''\emph{Nano Research,} vol. 10, no. 12, pp. 4003-4026, 2017.
DOI: https://doi.org/10.1007/s12274-017-1596-1.

{[}135{]} W.-Y. Tsai, R. Lin, S. Murali, L. Li Zhang, J. K. McDonough,
R. S. Ruoff, P.-L. Taberna, Y. Gogotsi and P. Simon, ``Outstanding
performance of activated graphene based supercapacitors in ionic liquid
electrolyte from -50 to 80 °C,'' \emph{Nano Energy,} vol. 2, no. 3, pp.
403-411, 2013. DOI: https://doi.org/10.1016/j.nanoen.2012.11.006.

{[}136{]} R. Younesi, G. M. Veith, P. Johansson, K. Edström and T.
Vegge, ``Lithium salts for advanced lithium batteries: Li-metal,
Li-O\textsubscript{2}, and Li-S,'' \emph{Energy \& Environmental
Science,} vol. 8, no. 7, pp. 1905-1922, 2015. DOI:
https://doi.org/10.1039/C5EE01215E.

\selectlanguage{english}
\FloatBarrier
\end{document}

