High-Performance MnO 2 Nanowire/MoS 2 Nanosheet Composite for a Symmetrical Solid-State Supercapacitor.

To improve the production rate of MoS 2 nanosheets as an excellent supercapacitor (SC) material and enhance the performance of the MoS 2 -based solid-state SC, a liquid phase exfoliation method is used to prepare MoS 2 nanosheets on a large scale. Then, the MnO 2 nanowire sample is synthesized by a one-step hydrothermal method to make a composite with the as-synthesized MoS 2 nanosheets to achieve a better performance of the solid-state SC. The interaction between the MoS 2 nanosheets and MnO 2 nanowires produces a synergistic effect, resulting in a decent energy storage performance. For practical applications, all-solid-state SC devices are fabricated with different molar ratios of MoS 2 nanosheets and MnO 2 nanowires. From the experimental results, it can be seen that the synthesized nanocomposite with a 1:4 M ratio of MoS 2 nanosheets and MnO 2 nanowires exhibits a high Brunauer-Emmett-Teller surface area (∼118 m 2 /g), optimum pore size distribution, a specific capacitance value of 212 F/g at 0.8 A/g, an energy density of 29.5 W h/kg, and a power density of 1316 W/kg. Besides, cyclic charging-discharging and retention tests manifest significant cycling stability with 84.1% capacitive retention after completing 5000 rapid charge-discharge cycles. It is believed that this unique, symmetric, lightweight, solid-state SC device may help accomplish a scalable approach toward powering forthcoming portable energy storage applications.