Synergistic design of Co(OH)2–Co3O4 composites via controlled drying for enhanced supercapacitor performance

Abstract

The rising demand for efficient energy storage has driven research into advanced electrode materials for supercapacitors. This study investigates Co(OH)2-Co3O4 composites, which combine the high supercapacitive activity of cobalt hydroxide with the structural stability of cobalt oxide. Synthesized via a simple hydrothermal method followed by drying at 60 °C, 80 °C, 100 °C, and 120 °C, the composites were characterized by X-ray diffraction, confirming the coexistence of both phases. The proportion of Co3O4 increased with dry temperatures. Nitrogen adsorption-desorption analysis revealed that the composites retained a mesoporous structure, with the 60 °C sample exhibiting the highest surface area (12 m2/g). The drying temperature had a strong influence on the phase composition, surface properties, and electrochemical behavior. Lower temperatures preserved a higher electroactive hydroxide content, thereby enhancing capacitance, while higher temperatures improved structural stability but reduced electrochemical performance. Electrochemical tests in a 1 M KOH electrolyte using a three-electrode system revealed that the 60°C sample delivered outstanding performance, achieving specific capacitances of 1679 F/g and 1243 F/g at 1 mV/s and 1 A/g, respectively. It also achieved an energy density of 62 Wh/kg at a power density of 395 W/kg. The structural integrity and high electrochemical performance of the electrode remain intact after the cyclic stability test. These results highlight the benefits of low-temperature drying in optimizing phase composition and surface characteristics, rendering Co(OH)2-Co3O4 a promising candidate for supercapacitor electrode applications.

Publication Title

Journal of Alloys and Compounds Communications

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