Direct regeneration and upcycling of cathode material from spent lithium ion batteries: Recent advances and perspectives

The explosive growth of lithium-ion batteries (LIBs) in consumer electronics, electric vehicles, and energy storage sectors has led to a focus on spent LIBs, particularly the handling of cathode material, driven by ecological concerns, the deed for stable LIB supply chains, and economic benefits. Current approaches to recovering spent cathodes primarily rely on hydrometallurgical or pyrometallurgical methods, which reference traditional Li/Ni/Co/Mn metallurgy and extraction processes. These methods degrade materials to the atomic level, and are energy-intensive, highly complex, and cost-inefficient. Recently, non-destructive methods, such as direct regeneration and upcycling of spent cathode materials, have gained favor among researchers due to their simplicity, cost-effectiveness, and significant upgrade potential. These methods target failure mechanisms to repair spent cathode materials such as through relithiation and lattice restoration, thereby recovering or enhancing their electrochemical performance. This review summarizes the failure mechanisms of mainstream cathode materials, such as layered oxides and olivine materials like LiFePO4, and provides insights into the latest developments in direct regeneration and upcycling, offering new perspectives for researchers.