Sustainable transformation of spent LiFePO4 cathodes into high-voltage olivine LiMnxFe1-xPO4 via solvothermal upcycling strategy for next-generation cathode material

With the retirement of a large number of lithium-ion batteries, how to efficiently recycle cathodes, especially for spent LiFePO 4 (S-LFP) olivine materials with low content of valuable elements, has become a research focus. Moreover, upcycling S-LFP to high-voltage olivine LiMn x Fe 1-x PO 4 (LMFP) is crucial for advancing next-generation cathode materials. Herein, this study proposes a solvothermal upcycling strategy that achieves complete elemental recovery and converts S-LFP into high-voltage LMFP. The resulting LMFP exhibits a uniform elemental distribution, attributed to the atomic-level miscibility of Fe and Mn. As a result, the regenerated LMn 0.5 Fe 0.5 PO 4 exhibits remarkable cycle stability with 83.8 % capacity retention after 2500 cycles at 5 C and a 40 % improvement in energy density (561 Wh kg -1 ) over that of S-LFP (402 Wh kg -1 ). This study presents an effective, direct upcycling route for the large-scale production of next-generation, high-performance olivine cathode materials while achieving sustainable reutilization of S-LFP through closed-loop life cycle management.