Cobalt hydroxide‐based electrodes for supercapacitors: Synthesis, characterization, and electrochemical performance optimization

Abstract

Abstract Dopant‐free cobalt hydroxides were synthesized via electrochemical deposition techniques, employing various precursors. The process involved preparing an aqueous electrolyte with a 0.1 M concentration of the respective precursor at ambient temperature (27°C). The synthesis of cobalt hydroxides was carried out using a two‐electrode system, with a controlled potential of 0.5 V. After the successful synthesis of dopant‐free cobalt hydroxides using the electrochemical deposition techniques with different precursors, the next step involved investigating these cobalt hydroxide electrodes. For this purpose, a three‐electrode system was utilized to analyze their cyclic voltammetry (CV), galvanostatic charge‐discharge (GCD), and electrochemical impedance spectroscopy (EIS) characteristics. Furthermore, to gain deeper insights into the properties of the cobalt hydroxide thin films, thorough examination was conducted using various techniques. X‐ray diffraction (XRD) was employed to study the crystal structure, scanning electron microscopy (SEM) to observe the surface morphology, and UV spectra to analyze the optical properties of the thin films. The investigations unveiled that the films displayed a crystalline nature with an average crystallite size of 40 nm. The morphology of the film appeared leaf‐like, and the particle size was measured to be 180 nm. Notably, the cobalt hydroxide electrodes demonstrated exceptional electrochemical performance. The specific capacitance, energy density, and power density of these electrodes were found to have average values of 1140 F/g, 142.5 Wh/kg, and 4.74 W/kg, respectively. These impressive results underscore the excellent performance and robust cycle stability of the cobalt hydroxide electrodes, making them highly promising for supercapacitor applications.