Direct regeneration of spent LiFePO ₄ cathode materials through Li ⁺ supplementation and Sm doping

Abstract

LiFePO₄ is widely used as a stable and environmentally benign cathode material. However, its reuse potential is constrained by recycling challenges and significant performance degradation after decommissioning. Therefore, how to effectively improve the electrochemical performance of regenerated LiFePO₄ materials and enhance their stability during cycling has become the focus of current research. In this research, Sm doping was introduced to optimize regenerated LiFePO₄ cathode materials via a plasma ball milling assisted solid-state calcination method. Comparison between spent LiFePO₄ and Sm-doped regenerated cathodes revealed that the appropriate level of Sm doping effectively maintained the crystal structure of LiFePO₄. It also promoted a more uniform particle morphology and a reduced particle size, which is beneficial for shortening Li⁺ transport pathways. This enhancement significantly improved electronic conductivity, leading to enhanced electrochemical performance. The 2% Sm doped regenerated material exhibited optimal performance, achieving an initial charge-discharge specific capacity of 142.2 mAh·g^–1 at 1 C and maintaining a capacity retention of 96.5% after 200 cycles. This conclusion is of significant importance for improving resource utilization efficiency of spent LiFePO₄ batteries.

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