Strongly coupled graphene/Mn3O4 composite with enhanced electrochemical performance for supercapacitor electrode

Strongly coupled graphene/Mn3O4 (GM) composite has been synthesized via a polyol process together with a subsequent thermal annealing treatment. Mn3O4 nanoparticles with an average diameter of 20 nm are uniformly adhered to a substrate of graphene sheets. The electrochemical properties of the composite for supercapacitor electrode in 1.0 M Na2SO4 aqueous solution were investigated by cyclic voltammetry (CV) and galvanostatic charge–discharge measurements. The GM composite exhibits more remarkable capacitance (270.6 F g-1 at 0.2 A g-1) compared with the pure Mn3O4 (132.0 F g-1 at 0.2 A g-1). After 1500 cycles, the retention rates of the composite and pure Mn3O4 at 2.0 A g-1 are 91% and 71.4%, respectively. The good electrochemical performance of the GM composite could be attributed to the decreased agglomeration, enhanced conductivity, and the robust structure as a result of introducing graphene. These results render a new reasonable design of preparing nanomaterials with complex structures for supercapacitor applications.