Flexible and Freestanding MoS 2 /Graphene Composite for High-Performance Supercapacitors.

Two-dimensional atomically thick materials such as graphene and layered molybdenum disulfide (MoS 2 ) have been studied as potential energy storage materials because of their high specific surface area, potential redox activity, and mechanical flexibility. However, because of the layered structure restacking and poor electrical conductivity, these materials are unable to attain their full potential. Composite electrodes made of a mixture of graphene and MoS 2 have been shown to partially resolve these issues in the past, although their performance is still limited by inadequate mixing at the nanoscale. Herein, we report three composites via a simple ball-milling method and analyze supercapacitor electrodes. Compared with pristine graphene and MoS 2 , the composites showed high capacitance. The as-obtained MoS 2 @Graphene composite (1:9) possesses a high surface area and uniform dispersion of MoS 2 on the graphene sheet. The MoS 2 @Graphene (1:9) composite electrode has a high specific capacitance of 248 F g -1 at 5 A g -1 in an electrochemical supercapacitor compared with the other two composites. Simultaneously, the flexible symmetric supercapacitor device prepared demonstrated superior flexibility and a long lifespan (93% capacitance retention after 8000 cycles) with no obvious changes in performance under different angles. In portable and wearable energy storage devices, the current experimental results will result in scalable, freestanding hybrid electrodes with improved, flexible, supercapacitive performance.