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

Electrode material based on a novel core-shell structure consisting of NiCo2S4 (NCS) solid fiber core and MnS (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@MnS/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 MnS at the same current density. A flexible all-solid-state asymmetric supercapacitor (ASC) is constructed by using NiCo2S4@MnS/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 about 7.5 kw kg(-1) at 10 A g(-1) and remarkable cycling stability. After 9000 cycles, the ASC still exhibited 67.8% retention rate and largely unchanged charge/discharge curves. The excellent electrochemical properties are resulted from the novel core-shell structure of the NiCo2S4@MnS/CC electrode, which possesses both high surface area for Faraday redox reaction and superior kinetics of charge transport. The NiCo2S4@MnS/CC electrode shows a promising potential for energy storage applications in the future. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.