Advancements in direct recycling technologies for lithium-ion battery cathodes: Overcoming challenges in cathode regeneration

Lithium-ion batteries (LIBs) currently dominate the energy storage landscape, generating a substantial volume of valuable waste resources at the end of their life and presenting additional recycling challenges and environmental hazards. Emerging direct recycling technologies offer promising solutions by rejuvenating spent electrode materials through simplified processes and surpassing traditional pyrometallurgical and hydrometallurgical technologies in terms of energy savings and carbon footprint reduction. The regeneration of high-value cathode materials has become especially interesting worldwide for reuse in the same battery applications, reducing dependence on raw materials and alleviating global supply chain burdens. Therefore, this review analyzes the current research in direct recycling technology, particularly relithiation techniques for restoring cathode performance without structural destruction, and sequential extraction steps and reuse in a straightforward manner. Advancements in direct recycling technologies such as chemical relithiation, electrochemical relithiation, solidstate sintering, and molten salts are discussed in detail for different cathode chemistries. Finally, the challenges present in direct recycling technologies are addressed to promote the regeneration process at an industrial level.