Abstract
The development of self-charging supercapacitor power cells (SCSPCs) has
profound implications for smart electronic devices used in different
fields. Here, we epitaxially electrodeposited Mo- and Fe-codoped MnO2
films on piezoelectric ZnO nanoarrays (NAs) grown on the flexible carbon
cloth (denoted ZnO@Mo-Fe-MnO2 NAs). An SCSPC device was assembled with
the ZnO@Mo-Fe-MnO2 NA electrode and
poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-Trfe) piezoelectric
film doped with BaTiO3 (BTO) and carbon nanotubes (CNTs) (denoted
PVDF-Trfe/CNTs/BTO). The SCSPC device exhibited an energy density of 30
μWh cm-2 with a high-power density of 40 mW cm-2, and delivered an
excellent self-charging performance of 363 mV (10 N) driven by both the
piezoelectric ZnO NAs and the PVDF-Trfe/CNTs/BTO films. More
intriguingly, the device also could also be self-charged by 184 mV due
to residual stress alone, and showed excellent energy conversion
efficiency and low self-discharge rate. This work illustrates for the
first time the self-charging mechanism involving electrolyte ion
migration driven by both electrodes and films. A comprehensive analysis
strongly confirmed the important contribution of the piezoelectric ZnO
NAs in the self-charging process of the SCSPC device. This work provides
novel directions and insights for the development of SCSPCs.