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

Room-temperature synthesized 3D hierarchical cobalt vanadate (Co 3 V 2 O 8 ) 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 K 3 [Fe(CN) 6 ] into the KOH electrolyte. Furthermore, the Co 3 V 2 O 8 /activated carbon asymmetric supercapacitor cell with the advanced electrolyte outperforms most reported Co 3 V 2 O 8 -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 Co 3 V 2 O 8 exhibits potential for practical application.