All-solid-state flexible asymmetric supercapacitors with high energy and power densities based on NiCo2S4@MnS and active carbon

摘要

Electrode material based on a novel core–shell structure consisting of NiCo2S4（NCS） solid fiber core and Mn S（MS） sheet shell（NCS@MS） in situ grown on carbon cloth（CC） has been successfully prepared by a simple sulfurization-assisted hydrothermal method for high performance supercapacitor. The synthesized NiCo2S4@Mn S/CC electrode shows high capacitance of 1908.3 F g-1 at a current density of 0.5 A g-1 which is higher than those of NiCo2S4 and Mn S at the same current density. A flexible all-solid-state asymmetric supercapacitor（ASC） is constructed by using NiCo2S4@Mn S/CC as positive electrode, active carbon/CC as negative electrode and KOH/poly（vinyl alcohol）（PVA） as electrolyte. The optimized ASC shows a maximum energy density of 23.3 Wh kg-1 at 1 A g-1, a maximum power density of about7.5 kw kg-1 at 10 A g-1 and remarkable cycling stability. After 9000 cycles, the ASC still exhibited67.8% retention rate and largely unchanged charge/discharge curves. The excellent electrochemical properties are resulted from the novel core–shell structure of the NiCo2S4@Mn S/CC electrode, which possesses both high surface area for Faraday redox reaction and superior kinetics of charge transport. The NiCo2S4@Mn S/CC electrode shows a promising potential for energy storage applications in the future.