Use of polyacrylonitrile-based carbon nanolayer modified Co3S4 to improve the overall performance of supercapacitors

Abstract

Transition metal sulfides with high theoretical specific capacitance are widely used as electrode materials for supercapacitors, but their poor cycling stability and energy density prevent them from meeting the needs of practical applications. To solve this problem, it is urgent to design an electrode material with excellent electrochemical performance. Here, polyacrylonitrile polymer layer-modified Co3S4 microspheres are anchored on a Ni foam substrate and then subjected to high-temperature carbonization to prepare a Carbon@Co3S4/Ni3S2/NF core–shell composite electrode. Its areal specific capacitance reached 1716 mF cm−2 at a current density of 1 mA cm−2 and 1128.9 mF cm−2 at 20 mA cm−2. Compared with the Co3S4/Ni3S2/NF electrode, its cycling stability is significantly improved, and the capacitance retention rate reaches 109% after 10,000 cycles. In addition, the assembled symmetrical supercapacitor achieves a higher energy density of 11.15 mWh cm−3 at a power density of 600 mW cm−3 and excellent cycling performance (approximately 90.3% capacitance retention over 5000 cycles). More importantly, this study illustrates a new method for improving the cycling stability and specific capacitance of transition metal sulfides, which provides the possibility of further practical application of the materials.