Advances in Co₃O₄-based electrodes for high-performance supercapacitors: structure design, mechanisms, and future perspectives

Transition metal oxides (TMOs) have attracted considerable interest as supercapacitor electrodes due to their high theoretical capacitance and reversible redox activity. Among them, cobalt oxide (Co₃O₄) stands out for its multiple oxidation states and favorable electrochemical properties. However, challenges such as limited conductivity and structural instability during cycling hinder its practical application. This review addresses these gaps by systematically analyzing recent advances in Co₃O₄-based materials, focusing on how synthesis strategies and morphological engineering influence electrochemical performance. Special attention is given to nanostructuring, composite formation, and dimensional control, which enhance ion transport and conductivity. Furthermore, the review discusses charge storage mechanisms and identifies critical limitations, proposing future research directions such as metal doping, hybrid device design, and scalable synthesis for industrial integration. By consolidating these insights, this work provides a roadmap for optimizing Co₃O₄-based electrodes for next-generation supercapacitors.