Advances in rare earth mineral extraction from waste for energy storage applications: A comprehensive review

Rare earth elements (REEs) are indispensable in modern energy storage systems due to their unique physicochemical properties, which enable high-performance batteries, supercapacitors, and fuel cells. However, the increasing demand for REEs and their uneven geographical distribution and environmentally intensive mining processes have intensified the search for sustainable and alternative sources. Waste materials, including industrial residues, electronic waste, coal fly ash, and end-of-life energy devices, represent a promising, underutilized reservoir of REEs. This review provides a comprehensive examination of recent advances in REE recovery from waste streams, focusing on applications in energy storage technologies. The discussion covers the types of REE-rich wastes, the roles of REEs in enhancing electrochemical performance, and the latest extraction strategies, including physical, chemical, biological, and advanced hybrid techniques. Challenges related to low REE concentrations, complex waste compositions, environmental risks, and economic feasibility are critically assessed. Furthermore, techno-economic analysis and life cycle considerations are explored to evaluate the sustainability of waste-derived REEs in a circular economy context. The review concludes with future research directions, including integration with renewable energy systems, policy and regulatory support, and the application of artificial intelligence for process optimization. This work highlights pathways toward a sustainable and resilient REE supply chain by bridging the gap between waste valorization and advanced energy storage.