He Kai, Zhang Zhi-Yuan, Zhang Fu-Shen
Department of Solid Waste Treatment and Recycling, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Department of Solid Waste Treatment and Recycling, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
J Hazard Mater. 2020 Aug 5;395:122614. doi: 10.1016/j.jhazmat.2020.122614. Epub 2020 Apr 7.
Recovery of high-content and valuable elements including phosphorus (P) is critical for recycling of spent LiFePO battery, but P recovery is challengeable due to the poor solubility of lithium phosphate and iron phosphate. This study compared two strategies to recover P by adopting sulfide salt to induce P dissolution, i.e., recovery of P directly from LiFePO, and step-by-step recovery of Li then P. The results revealed that the second strategy was more efficient because of the higher recovering efficiency and selectivity. Accordingly, an acid-free process to recover P was successfully demonstrated. Li-recovery efficiency of 97.5 % was reached at a leaching time of 65 min, and nearly 100 % P-recovery efficiency was reached at 5 h. Mechanism analysis revealed that the transforming of delithiated LiFePO crystal to NaFeS was mainly responsible for P dissolution. Thermodynamic analysis and density functional theory calculation further proved the transformation reaction, and a stepwise-transformation mechanism was proposed. In addition, P was reclaimed in the form of soluble phosphate salts. The process is especially appealing due to its environmental and economic benefits for recycling spent LiFePO batteries.
回收包括磷（P）在内的高含量和有价值元素对于废旧磷酸铁锂（LiFePO）电池的回收利用至关重要，但由于磷酸锂和磷酸铁的溶解性较差，磷的回收具有挑战性。本研究比较了两种采用硫化物盐诱导磷溶解来回收磷的策略，即直接从LiFePO中回收磷，以及先回收锂再回收磷的分步回收策略。结果表明，第二种策略效率更高，因为其回收效率和选择性更高。据此，成功展示了一种无酸回收磷的工艺。在浸出时间为65分钟时，锂回收效率达到97.5%，在5小时时，磷回收效率接近100%。机理分析表明，脱锂的LiFePO晶体向NaFeS的转变是磷溶解的主要原因。热力学分析和密度泛函理论计算进一步证实了该转变反应，并提出了分步转变机理。此外，磷以可溶性磷酸盐的形式回收。该工艺因其对废旧LiFePO电池回收的环境和经济效益而特别具有吸引力。
