Closed-Loop Recycling Methods to Treat Spent Cathode: Efficient and Direct Regeneration

Direct regeneration of spent lithium batteries (LIBs) cathodes has emerged as a transformative regimen to address the urgent need for sustainable recycling methods and mitigate the critical shortage of metal resources driven by the escalating LIB demand. Unlike conventional methods focused on metal extraction and separation, direct regeneration restores the functionality of spent cathode in situ, streamlining the recycling process and enhancing efficiency. Effective regeneration necessitates a comprehensive understanding of cathode failure mechanisms and the pretreatment processes. Critical strategies include reducing lithium (Li) migration barrier to enable complete reinsertion into cathode structure and minimizing Li-transition metal anti-site defects to reconstruct the cathode lattice. This review summarizes advancements in failure mechanisms, pretreatment techniques, and the direct recycling strategies of spent cathode, emphasizing principles and innovations in direct regeneration. By evaluating the advantages and limitations of current approaches, opportunities are identified for innovation to overcome existing challenges. Future research priorities are proposed to advance direct regeneration technologies, fostering more efficient and sustainable LIB recycling systems.