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

Abstract

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.

Keywords

• supercapacitor
• zeolitic imidazolate frameworks
• Co₂VO₄ nanocubes
• hollow structures