Upcycling and recycling of spent battery waste for a sustainable future: Progress and perspectives

The urgency of addressing the environmental and resource challenges posed by spent lithium-ion batteries (LIBs) has led to significant advancements in recycling and upcycling methodologies. This work aims to provide a comprehensive understanding of the progress made for LIB recycling and upcycling, offering perspectives for achieving a circular economy in battery technology. The review examines the latest innovations in LIB material recovery, focusing on both conventional recycling techniques and emerging upcycling strategies. It explores the motivation and importance of recycling spent LIBs, showing the critical need for sustainable solutions. A comprehensive overview of LIB recycling methodologies is provided, including pretreatment, preprocessing, pyrometallurgical, hydrometallurgical, bioleaching, direct recovery processes, electrochemical processes, and deep eutectic solvents. Emphasis is placed on the advanced upcycling of the cathode, anode, and separator materials, exploring composition/crystallisation engineering and structural modifications, including doping and surface coating. Furthermore, upcycling spent LIB materials into high-value products like catalysts and graphene is explored. The environmental impact, legislative landscape, and socioeconomic implications of battery recycling are critically analysed, with life cycle assessments underscoring the ecological benefits of these processes. Global perspectives on battery recycling practices are also examined, considering the varied approaches across different regions. Additionally, integrating artificial intelligence and the internet of things in optimising battery recycling is explored, demonstrating their potential to enhance efficiency and sustainability. The review concludes by identifying current challenges and proposing recommendations for future research and policy development.