Hierarchical MoS 2 -coated three-dimensional graphene network for enhanced supercapacitor performances

Abstract

Abstract Layered molybdenum disulfide (MoS 2 ) owns graphene-like two-dimensional structure, and when used as the electrode material for energy storage devices, the intercalation of electrolyte ions is permitted. Herein, a simple dipping and drying method is employed to stack few-layered MoS 2 nanosheets on a three-dimensional graphene network (3DGN). The structure measurement results indicate that the assembled hierarchical MoS 2 nanosheets own expanded interlayer spacing (∼0.75 nm) and are stacked on the surface of 3DGN uncontinuously. The composite can achieve 110.57% capacitance retention after 4000 cycles of galvanostatic charge/discharge tests and 76.73% capacitance retention with increasing the current density from 1 A g −1 to 100 A g −1 . Moreover, the asymmetric coin cell supercapacitor using MoS 2 @3DGN and active carbon as electrode materials is assembled. This device could achieve a working voltage window of 1.6 V along with the power and energy densities of 400.0–8001.6 W kg −1 and 36.43–1.12 Wh kg −1 respectively. The enhanced electrochemical performance can be attributed to: (1) the expanded interlayer spacing of hierarchical MoS 2 nanosheets which can facilitate the fast intercalation/deintercalation of electrolyte cations, (2) the uncontinuous deposition of hierarchical MoS 2 nanosheets which facilitates more contact between electrolyte and the section of MoS 2 nanosheets to provide more gates for the intercalation/deintercalation.