Recycling and crystal regeneration of commercial used LiFePO₄ cathode materials

Currently extensive attentions on recycling application from scrapped LiFePO₄ power batteries of electric vehicles is attracted to the researchers. Owing to its stable olivine crystal structure and expensive preparation process relative to other cathode materials, the re-synthesis of LiFePO₄ from spent batteries becomes an economical and convenient way. Herein, we combine the mechanical separation and high-temperature pyrolysis to regenerate the performance of used LiFePO₄ cathode materials from retired electric vehicles. Spent LiFePO₄ cathode material is first successfully regenerated through Li/Fe/P elements compensation and structure reshaping via heat treatment method. The results show that when the content of Li/Fe/P elements in the used LiFePO₄ material is restored to the initial conditions, the surface and particle sizes of the material are recovered to smooth and small, respectively. From the crystal structure, the crystal distortion of the used LiFePO₄ material is also repaired, indicating by the restored interplanar spacing of the (111) plane and the improved crystallinity. With the successful repair of microstructures and components, the electrochemical performance of the repaired LiFePO₄ is reverted, such as long cycle and rate performance, when compared with the used LiFePO_4.