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Carbon waste poses environmental risks but offers a resource for energy storage materials. This review focuses on converting three representative carbon wastes—biomass, plastics, and spent lithium-ion battery (LIB) anodes—into graphene-based materials for supercapacitors (SCs) and LIBs, analyzing preparation methods and trends. Biomass conversion research is comprehensive, targeting fewer layers, porosity, and doping. Waste plastic conversion mainly uses pyrolysis, with flash Joule heating (FJH) emerging, and modified Hummers methods are common for spent graphite. Preparation is device specific: SCs favor activation for high surface area and porosity, while LIB anodes benefit from defects and doping to enhance Li-ion insertion. Ball milling stands out as a potentially scalable and green approach applicable across different wastes. However, studies on upcycling plastics and graphite remain limited, indicating future directions. Critically, this review evaluates secondary pollution, highlighting environmental advantages of mechanical activation, FJH, and modified Hummers methods.
Peng et al. (Mon,) studied this question.