From Delithiated Residues to High-Performance LiMn0.4Fe0.6PO4 through Structural Inheritance and F-Doping toward...

The sustainable upcycling of delithiated FePO4 and MnO2 residues from spent lithium-ion batteries (LIBs) is challenged by fluoride cross-contamination, crystalline incompatibility, and low economic value. Herein, a direct mechanochemical regeneration strategy is proposed to convert FePO4 and MnO2 into high-performance F-doped LiMn0.4Fe0.6PO4, featuring the structurally inherited robust olivine framework of FePO4, defect-enabled homogeneous Mn incorporation from MnO2, and stabilized Mn/Fe-O bonding network through F-doping. As a result, the optimized material delivers a high capacity of 136.76 mAh g-1 at 1 C with 89.74% retention after 600 cycles and 118.74 mAh g-1 at 10 C. Mechanistic analyses reveal that defect-mediated Mn/Fe intermixing and F-doping synergistically suppress Jahn-Teller distortion, enhance structural stability, and improve Li+ diffusion. Technoeconomic and environmental assessments suggest the well-round efficiency of the upcycling route with elucidated structural evolution of LiMnxFe1-xPO4 (LMFP) and functional modification of the F element, thereby establishing a practical candidate toward sustainable upcycling of spent LIBs.