Sustainable Electrochemical Recycling of Spent Zinc–Carbon and Alkaline Batteries to Produce Graphene for High-Performance Supercapacitors

Abstract

This paper demonstrates a simple and environmentally friendly approach for recycling spent batteries to produce graphene materials for supercapacitor applications. Using electrochemical exfoliation, graphene was successfully synthesized from the graphite cores of discarded zinc–carbon and alkaline batteries. The synthesized graphene was subsequently employed as an active electrode material for symmetric supercapacitors. Structural characterization via XRD, SEM, EDX, and Raman spectroscopy confirms that the recycled graphene exhibits a well-defined layered structure, high carbon purity (> 80 wt%), large specific surface area, and appropriate surface chemistry. Electrochemical measurements demonstrate that supercapacitors based on recycled graphene electrodes exhibit near-ideal capacitive behavior, rapid charge–discharge response, and excellent cycling stability with over 90% capacitance retention after 1,000 charge–discharge cycles. Compared with conventional battery recycling methods such as mechanical separation, pyrometallurgy, and hydrometallurgy, the proposed electrochemical exfoliation approach offers clear advantages including lower energy consumption, reduced chemical usage, and the production of high-value nanomaterials. This approach not only contributes to mitigating environmental pollution associated with hazardous waste from spent batteries but also enables the production of high-value graphene at significantly lower cost than commercial materials, aligning with circular economy principles and supporting the development of sustainable energy storage systems.