Effect of Different Annealing Temperatures on the Performance of Electrodeposited Cobalt Oxide Thin Films Used to Fabricate Supercapacitor Electrodes

Present work explored the impact of various annealing temperatures on a thin layer of cobalt oxide (Co₃O₄) and characterization for its structural and electrochemical properties for supercapacitor application. Co₃O₄ thin films were produced following electrodeposition at room temperature on a conductive stainless steel substrate (SS). The samples were annealed for 1 h at 200, 300, 400, 500, and 700 °C. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques were used to examine the impact of annealing temperature on the structural and morphological properties of Co₃O₄ thin films. A discernible change in the morphology of Co₃O₄ thin films was observed after annealing, with improvements in their crystallinity, surface coverage and grain connectivity. The electrodes composed of Co₃O₄/SS exhibited a greater capacity of holding charge compared to electrodes treated at the maximum annealing temperature (489.23 F.g^–1 at 20 mV s^–1). Cobalt oxide electrodes annealed at 200 °C were characterized by superior ionic accessibility than those annealed at higher temperatures. These outcomes demonstrated that a simple and inexpensive electrodeposition technique could be used to fabricate electrodes at 200 °C to develop supercapacitors.