3D hierarchical cobalt vanadate nanosheet arrays on Ni foam coupled with redox additive for enhanced supercapacitor performance

Room-temperature synthesized 3D hierarchical cobalt vanadate (Co₃V₂O₈) nanosheet arrays on Ni foam for use as supercapacitor electrode is presented. In a 3 M KOH electrolyte, the electrode exhibits a capacitance of 109.9 mA h g⁻¹ (878.9 F g⁻¹) at a current density of 1 A g⁻¹. The capacitance is enhanced to 198.1 mA h g⁻¹ (1584.5 F g⁻¹) at 1 A g⁻¹ through the addition of 0.05 M redox-additive K₃[Fe(CN)₆] into the KOH electrolyte. Furthermore, the Co₃V₂O₈/activated carbon asymmetric supercapacitor cell with the advanced electrolyte outperforms most reported Co₃V₂O₈-based electrodes with a remarkable energy density of 55.5 W h kg⁻¹ at an 800 W kg⁻¹ power density. Combining a facile synthetic strategy and excellent electrochemical performance, the obtained Co₃V₂O₈ exhibits potential for practical application.