Waste-to-carbon-based supercapacitors for renewable energy storage: progress and future perspectives

Abstract The increasing demand for cost-effective materials for energy storage devices has prompted investigations into diverse waste derived electrode materials for supercapacitors (SCs) application. This review examines advancements in converting waste into carbon-based SCs for renewable energy storage. In this context, different carbon-based waste precursor sources have been explored over the years as electrodes in SCs. These waste sources comprise of industrial, plastics and biowastes, including plant and animal wastes. The energy storage capabilities of the various waste derived SCs electrodes are highlighted to provide an understanding into the unique features that make them applicable to SCs. In addition, some challenges associated with the waste-derived SCs electrodes in terms of energy storage have been emphasized. Here, we also provided insights into the recent progress in SCs electrode synthesis techniques and their effects on electrochemical performance. SCs performance tailoring with material structures through the incorporation of different materials to form composites and optimized synthesis methods is an effective strategy. Hence, the synthesis methods outlined include pyrolysis, hydrothermal, microwave-assisted, template-assisted, and sol–gel techniques. The effect of the various synthesis methods on SCs performance has also been discussed. Overall, this review highlights waste valorization with future research directions and scaling challenges.