Hierarchical nickel cobalt sulfide nanosheet on MOF-derived carbon nanowall arrays with remarkable supercapacitive performance

Abstract

Nickel cobalt sulfide (CoNi2S4)-based materials have attracted extensive attention as electrodes which arise from their high theoretical capacitance, but their wide application is limited by relatively low electrical conductivity and electrochemical stability. Herein, the metal-organic framework (MOF) derived carbon nanowall arrays (CNWAs) are successfully fabricated on carbon cloth (CC) as secondary substrate, which provides more sites for electrodeposition of CoNi2S4. Furthermore, the integration of Ni layer to bridge CoNi2S4 and CNWAs, which is favorable for fast charge transfer, as well as improved conductivity. Thus, the CC/CNWAs@Ni@CoNi2S4 electrode exhibits a remarkable specific capacitance (3163 F g−1/2825 F g−1 at 1 A g−1/5 mV s−1) and rate capability (1503 F g−1/1500 F g−1 at 40 A g−1/50 mV s−1), outperforming others CoNi2S4-based electrodes reported previously. The as-prepared CC/CNWAs@Ni@CoNi2S4//commercial activated carbon asymmetric supercapacitor demonstrates superior electrochemical performance with maximum energy density of 53.8 W h kg−1 at a power density of 801 W kg−1 and long-term cycling stability with 90.1% retention after 10 000 cycles. These remarkable supercapacitive performances are attributed to the rationally hierarchical architecture, high utilization ratio of active materials and aligned ion diffusion channels of the CC/CNWAs@Ni@CoNi2S4 electrode.