Phase Change Mechanism of Spent LiFePO4 Cathode Material in Regeneration Process

New energy vehicles are gradually becoming widespread in China, and the quantity of installed and retired power LiFePO₄ batteries has increased. The traditional wet recovery process of LiFePO₄ cathode materials produces a lot of waste acid and waste alkali, which is inconsistent with the modern industrial concept of zero emissions and zero waste. This paper proposes a novel environmental protection process for direct remediation of spent LiFePO₄. Li₂CO₃ is the lithium source, and expired food-grade sucrose is used to reduce the spent LiFePO₄ cathode materials, which are then regenerated under the premise of achieving zero emissions and zero waste. When the addition of Li₂CO₃ is 4 wt% and the sucrose content is 15 wt%, the regenerated LiFePO₄/C material exhibits uniform particle size and favorable morphology. At 0.1 C, the initial discharge specific capacity is 156.15 mAh g^-1. At 5 C, its discharge performance is 106.01 mAh g^-1, and the electrochemical performance of the regenerated LiFePO₄/C material is similar to that of the commercial LiFePO₄. Moreover, the regulation mechanism of lithium replenishment repair in LiFePO₄ cathode materials is explored from the perspectives of material structure and physical phase composition.