Recycling Critical Metals from Spent Lithium-Ion Battery Cathodes: Technologies, Challenges, and Perspectives to Sustainable Closed-Loop Systems

The rapid increase of lithium-ion batteries (LIBs) faces severe challenges. Due to the environmental effects from numerous spent LIBs and the imbalanced supply demand of raw materials, recycling of spent LIBs is urgently needed. However, at present recycling techniques face significant hindrances, such as inefficient metal separation, high energy consumption, and secondary pollution. This review demonstrates a detailed analysis of commercial LIB cathode materials that refers to both merits and limitations from technological and industrial aspects. Moreover, the entire recycling chain is systematically investigated, including pretreatment and mainstream recycling methods, such as pyrometallurgy, hydrometallurgy, bioleaching, and direct regeneration. Meanwhile, optimization pathways for separation techniques are discussed. Finally, a multicriteria framework for evaluating cathode material recycling technologies is developed, which comprises energy consumption, environmental impact, cost, recycling efficiency, and closed-loop duration. It provides insights for optimizing sustainable processes. This review discusses the technology for recycling cathode materials in LIBs and proposes strategies for renewable energy.