From Delithiated Residues to High-Performance LiMn<sub>0.4</sub>Fe<sub>0.6</sub>PO<sub>4</sub> through Structural Inheritance and F-Doping toward Upcycling of Spent Lithium-Ion Batteries.

Yan, Shuxuan; Chen, Xiangping; Wang, Xiaowei; Guo, Linling; Huang, Zhiqiang; Sun, Qing; Yuan, Lu; Zhao, Haihong et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

The sustainable upcycling of delithiated FePO<sub>4</sub> and MnO<sub>2</sub> 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 FePO<sub>4</sub> and MnO<sub>2</sub> into high-performance F-doped LiMn<sub>0.4</sub>Fe<sub>0.6</sub>PO<sub>4</sub>, featuring the structurally inherited robust olivine framework of FePO<sub>4</sub>, defect-enabled homogeneous Mn incorporation from MnO<sub>2</sub>, 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<sup>-1</sup> at 1 C with 89.74% retention after 600 cycles and 118.74 mAh g<sup>-1</sup> 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<sup>+</sup> diffusion. Technoeconomic and environmental assessments suggest the well-round efficiency of the upcycling route with elucidated structural evolution of LiMn<sub><i>x</i></sub>Fe<sub>1-<i>x</i></sub>PO<sub>4</sub> (LMFP) and functional modification of the F element, thereby establishing a practical candidate toward sustainable upcycling of spent LIBs.