Dual additives for stabilizing Li deposition and SEI formation in
anode-free Li metal batteries
Abstract
Anode-free Li-metal batteries (AFLBs) are of significant interest to
energy storage industries due to their intrinsically high energy.
However, the accumulative Li dendrites and dead Li continuously consume
active Li during cycling. That results in a short lifetime and low
Coulombic efficiency (CE) of AFLBs. Introducing effective electrolyte
additives can improve the Li deposition homogeneity and solid-state
interphase (SEI) stability for AFLBs. Herein, we reveal that introducing
dual additives, composed of LiAsF6 and FEC, into a commercial carbonate
electrolyte will boost the cycle life and average CE of
NCM||Cu AFLBs. The NCM||Cu AFLBs
with the dual additives exhibit a capacity retention of about 75% after
50 cycles, much higher than those with bare electrolytes (35%). The
average CE of the NCM||Cu AFLBs with additives can
maintain 98.3% over 100 cycles. In contrast, the average CE without
additives rapidly decline to 97% after only 50 cycles. In situ Raman
measurements reveal that the prepared dual additives facilitate denser
and smoother Li morphology during Li deposition. The dual additives
significantly suppress the Li dendrite growth, enabling stable SEI
formation on anode and cathode surfaces. Our results provide a broad
view of developing low-cost and high-effective functional electrolytes
for high-energy and long-life AFLBs.