Rationally designed hierarchical ZnCo2O4/C core-shell nanowire arrays for high performance and stable supercapacitors

Abstract

ZnCo2O4 possess a high theoretical specific capacity, but low conductivity, poor stability and short cycle life hinder its practical application. In order to overcome those disadvantages of ZnCo2O4, herein, porous ZnCo2O4/Carbon (ZnCo2O4/C) core-shell nanowire arrays (NWAs) grown on Ni foam was synthesized by simple hydrothermal method and followed chemical vapor deposition. Compared with the pure ZnCo2O4, deposition of carbon offers an opportunity to significantly improve the conductivity, stability, and electrochemical performance of ZnCo2O4 NWAs. The ZnCo2O4/C electrodes deliver a high areal capacitance of 7.02 F cm−2 (2340 F g−1) and superior cycling stability of 92.6% after 10,000 cycles at 20 mA cm−2. Moreover, an asymmetric supercapacitor (ASC) was assembled with ZnCo2O4/C NWAs as the positive electrode and activated carbon (AC) as the negative electrode. The ASC device shows a high energy density of 35.75 Wh kg−1 at a power density of 73.17 W kg−1 and 73.3% of capacitance retention over 10,000 cycles. In brief, the ZnCo2O4/C NWAs are expected to be a promising material for energy storage devices of high-performance supercapacitor.