High-Performance MnO₂ Nanowire/MoS₂ Nanosheet\nComposite for a Symmetrical Solid-State Supercapacitor

Abstract

To improve the production\nrate of MoS₂ nanosheets as\nan excellent supercapacitor (SC) material and enhance the performance\nof the MoS₂-based solid-state SC, a liquid phase exfoliation\nmethod is used to prepare MoS₂ nanosheets on a large scale.\nThen, the MnO₂ nanowire sample is synthesized by a one-step\nhydrothermal method to make a composite with the as-synthesized MoS₂ nanosheets to achieve a better performance of the solid-state\nSC. The interaction between the MoS₂ nanosheets and MnO₂ nanowires produces a synergistic effect, resulting in a decent\nenergy storage performance. For practical applications, all-solid-state\nSC devices are fabricated with different molar ratios of MoS₂ nanosheets and MnO₂ nanowires. From the experimental\nresults, it can be seen that the synthesized nanocomposite with a\n1:4 M ratio of MoS₂ nanosheets and MnO₂ nanowires\nexhibits a high Brunauer–Emmett–Teller surface area\n(∼118 m²/g), optimum pore size distribution, a specific\ncapacitance value of 212 F/g at 0.8 A/g, an energy density of 29.5\nW h/kg, and a power density of 1316 W/kg. Besides, cyclic charging–discharging\nand retention tests manifest significant cycling stability with 84.1%\ncapacitive retention after completing 5000 rapid charge–discharge\ncycles. It is believed that this unique, symmetric, lightweight, solid-state\nSC device may help accomplish a scalable approach toward powering\nforthcoming portable energy storage applications.