Porous graphene–NiCo2O4 nanorod hybrid composite as a high performance supercapacitor electrode material

Abstract

The template free low temperature solvothermal synthesis of high capacitive porous graphene–NiCo₂O₄ nanorod composites has been carried out. Solvothermal synthesis followed by calcination in air led to the development of a highly porous hybrid nanocomposite, which acts as a buffering channel for fast ion diffusion and provides robust mechanical strength. Advantages of using porous graphene to enhance the capacitance of the material were studied theoretically using First principles calculations. High capacitance values of 1533 F g⁻¹ at a scan rate of 5 mV s⁻¹ and 1684 F g⁻¹ at a current density of 1 A g⁻¹ are obtained from cyclic voltammetry data and galvanostatic charge discharge data, respectively. The electrode material possesses good cyclic stability with the retention of 94% of its initial capacitance even after 10 000 charge–discharge cycles at a current density of 8 A g⁻¹ in 2 M KOH electrolyte. The fabricated supercapacitor exhibited a high energy density of 45.3 W h kg⁻¹ and a high power density of 17843.5 W kg⁻¹ due to the synergistic effect of the composite components. The enhanced electrochemical function of the composite makes it a potential candidate for supercapacitor application and future studies.