Electrodeposited Co 3 O 4 Thin Film Over Stainless Steel Substrate for High-Performance Supercapacitor Electrodes

An efficient energy storage system requires an excellent electrode material that is easy and inexpensive to fabricate. In this study, we attempted to synthesize cobalt oxide thin films on SS-304 substrates and study the influence of the annealing temperature on the structure, surface morphology, and electrochemical performance. The samples were synthesized using the potentiostatic electrodeposition technique, followed by annealing at different temperatures (350, 400, and 450 °C). The synthesized samples were found to be porous. The maximum specific capacitance of CO-350, estimated via galvanostatic charge discharge analysis, was 416 F g −1 at 0.5 A g −1 with a good energy density of 10.1 W.h kg −1 . Electrodes directly fabricated in thin films over substrates are very beneficial for device design. Electrochemical impedance spectroscopy results suggest minimal diffusion resistance of the electrolyte ions, confirming the good conductivity of the samples. The overall electrochemical performance highlights the potential of Co 3 O 4 thin films annealed at 350 °C as efficient electrode materials for high-performance supercapacitors.