Free-standing graphene/bismuth vanadate monolith composite as a binder-free electrode for symmetrical supercapacitors

Preparation of new types of electrode material is of great importance to supercapacitors. Herein, a graphene/bismuth vanadate (GR/BiVO4) free-standing monolith composite has been prepared via a hydrothermal process. Flexible GR sheets act as a skeleton in the GR/BiVO4 monolith composites. When used as a binder-free electrode in a three-electrode system, the GR/BiVO4 composite electrode can provide an impressive specific capacitance of 479 F g(-1) in a potential window of -1.1 to 0.7 V vs. SCE at a current density of 5 A g(-1). A symmetrical supercapacitor cell which can be reversibly charged-discharged at a cell voltage of 1.6 V has been assembled based on this GR/BiVO4 monolith composite. The symmetrical capacitor can deliver an energy density of 45.69 W h kg(-1) at a power density of 800 W kg(-1). Moreover, it ensures rapid energy delivery of 10.75 W h kg(-1) with a power density of 40 kW kg(-1).