Fabrication of high energy density symmetric supercapacitor based on cobalt-nickel bimetallic tungstate nanoparticles decorated phosphorus-sulphur co-doped graphene nanosheets with extended voltage

The present study reports the hydrothermal synthesis and electrochemical performance of bimetallic Cobalt-Nickel tungstate nanoparticles and its composite with Phosphorous-Sulphur co-doped graphene as a supercapacitor electrode material. The materials are characterized by different structural and surface techniques which confirm that bimetallic tungstate particles are uniformly anchored on the surface of co-doped graphene. The active materials are directly drop casted on the surface of glassy carbon electrode for initial studies. The electrochemical investigations reveal that bimetallic tungstate and hybrid composite exhibit high specific capacitance of 723.8 F.g(-1) and 1298.6 F.(g-1) respectively at the current density of 0.5 A. g(-1) in 6M KOH as an electrolyte. The synergy between bimetallic tungstate particles and doubly doped graphene significantly enhances the porosity, conductivity, surface area and induced structural stability of the hybrid composite for electrochemical processes. Based on these results, we have constructed symmetric supercapacitor using the composite material which delivers high voltage output of 1.6 V, remarkable energy density of 100.8 Wh.kg(-1) and power density of 3234.2 W.kg(-1) at current density of 0.5 A.g(-1). These results demonstrate that the hybrid composite has a positive prospect in the preparation of high performance composite electrodes for advanced electrochemical energy storage applications.