Phase Change Mechanism of Spent LiFePO4 Cathode Material in Regeneration Process
摘要
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.