Self‐Powered Piezo‐Supercapacitors Based on ZnO@Mo‐Fe‐MnO2 Nanoarrays

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 MnO 2 films on piezoelectric ZnO nanoarrays (NAs) grown on the flexible carbon cloth (denoted ZnO@Mo‐Fe‐MnO 2 NAs). A self‐charging supercapacitor power cell device was assembled with the Mo‐ and Fe‐codoped MnO 2 nanoarray electrode and poly(vinylidenefluoride‐co‐trifluoroethylene) (PVDF‐Trfe) piezoelectric film doped with BaTiO 3 (BTO) and carbon nanotubes (CNTs) (denoted PVDF‐Trfe/CNTs/BTO). The self‐charging supercapacitor power cell 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 nanoarrays and the poly(vinylidenefluoride‐co‐trifluoroethylene) piezoelectric film doped with BaTiO 3 and carbon nanotubes. More intriguingly, the device 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 nanoarrays in the self‐charging process of the self‐charging supercapacitor power cell device. This work provides novel directions and insights for the development of self‐charging supercapacitor power cells.