Al2O3-assisted synthesis of hollow CuCo2S4 nanospheres with rich sulfur vacancies for hybrid supercapacitor

Abstract

Preparing hollow materials with a large active surface area is a highlight for energy storage materials. In this work, hollow CuCo2S4 is synthesized via a hard template of commercial Al2O3 at a low cost, and S-vacancies are introduced to enhance the electronic conductivity (rh-CuCo2S4). The template Al2O3 is completely removed by the solvothermal reaction without damaging the hollow structure of CuCo2S4. The rh-CuCo2S4 demonstrates a specific area of 99.5 m2 g–1, higher than that of CuCo2S4 without the Al2O3 template. The rh-CuCo2S4 electrode performs a high specific capacity (247.1 mAh g–1 at 1 A g–1), favorable rate performance, and decent cycling performance (81.1% after 13,000 cycles at 10 A g–1). An asymmetric rh-CuCo2S4//AC hybrid supercapacitor shows an energy density of 77.6 W h kg–1 at the power density of 612 W kg–1 and a maximum power density of 7.3 kW kg–1 at the energy density of 42.5 W h kg–1. The excellent stability of rh-CuCo2S4//AC hybrid supercapacitor is also obtained with a retention of 84.9% after 10,000 cycles at 10 A g–1. The favorable performance of rh-CuCo2S4 is attributed to the increasing charge diffusion channels bases on the hollow morphology and the enhanced electronic conductivity and reaction activity due to S-vacancies. This work provides a low-cost and efficient approach to preparing sulfides with high performance in energy storage applications.