ZIF-67 Derived Co₂VO₄ Hollow Nanocubes for High Performance Asymmetric Supercapacitors

In this work, a new type of Co₂VO₄ hollow nanocube (CoVO-HNC) was synthesized through an ion exchange process using ZIF-67 nanocubes as a template. The hollow nanocubic structure of the CoVO-HNC provides an abundance of redox sites and shortens the ion/electron diffusion path. As the electrode material of supercapacitors, the specific capacitance of CoVO-HNC is 427.64 F g^-1 at 1.0 A g^-1. Furthermore, an asymmetric supercapacitor (ASC) was assembled using CoVO-HNC and activated carbon (AC) as electrodes. The ASC device attains an energy density of 25.28 Wh kg^-1 at a high-power density of 801.24 W kg^-1, with 78% capacitance retention after 10,000 cycles at 10 A g^-1.