Regeneration of spent lithium-ion battery materials

Lithium-ion batteries (LiBs) have excellent electrical properties and are widely used in many application domains. With the remarkable development of the LiBs industry, the number of spent LiBs has dramatically increased. To reduce environmental pollution and resource depletion, several technologies for recycling and regenerating LiBs have been developed, especially for valuable metals, such as lithium, manganese, cobalt, nickel, and copper. The reuse of LiB materials via regeneration is one of the cleanest and cheapest approaches. This study first analyses the structure and composition of a typical LiBs and classifies the regeneration methods based on their structure. Owing to the varied measurement conditions of different regeneration methods, which cannot be compared directly, a normalised transformation method for LiBs is proposed to calculate and compare the results under different discharge current rates (Crates) and cycles. Furthermore, the degradation mechanism of LiB materials is analysed. Finally, novel green regeneration technologies are summarised. This review aims to develop a deep understanding of regeneration methods through comparison and analysis and identify the most promising regeneration methods. The analysis shows that designing a fully recyclable and regenerative LiB is the most promising method to solve the problem of spent LiBs.