Effect of cobalt doping on the enhanced energy storage performance of 2D vanadium diselenide: experimental and theoretical investigations.

Vanadium Diselenide (VSe) is a prominent candidate in the 2D transition metal dichalcogenides family for energy storage applications. Herein, we report the experimental and theoretical investigations on the effect of cobalt doping in 1T-VSe. The energy storage performance in terms of specific capacitance, stability and energy and power density is studied. It is observed that 3% Co doped VSeexhibits better energy storage performance as compared to other concentrations, with a specific capacitance of ∼193 F gin a two-electrode symmetric configuration. First-principles Density Functional Theory based simulations support the experimental findings by suggesting an enhanced quantum capacitance value after the Co doping in the 1T-VSe. By making use of the advantages of the specific electrode materials, a solid state asymmetric supercapacitor (SASC) is also assembled with MoSas the negative electrode. The assembled Co-VSe//MoSSASC device shows excellent energy storage performance with a maximum energy density of 33.36 Wh kgand a maximum power density of 5148 W kgwith a cyclic stability of 90% after 5000 galvano static charge discharge cycles.