废旧磷酸铁锂正极材料的高价值回收利用

High-value recycling of spent lithium iron phosphate cathode materials

  • 摘要: 文中介绍了一种对废旧磷酸铁锂正极材料进行高价值回收利用的方法。材料中的Fe、P、Li元素分别以FeSO4、FePO4和Li3PO4形式回收,以Li3PO4形式回收Li的回收率达到93%。该回收工艺不使用磷酸或磷酸盐,具体包括5个步骤:①将废旧磷酸铁锂正极材料用硫酸酸溶;②将1/3以上的Fe2+离子以FeSO4形式重结晶出来;③对Fe2+进行氧化处理并调整溶液pH至2.0~3.0,使Fe2+离子以FePO4形式析出,制得的FePO4可以用于固相法制备LiFePO4;④将分离FePO4后滤液的pH调至11.0,其中的Li+、PO43-离子浓度达到沉淀析出条件,析出Li3PO4沉淀;⑤将制得的亚铁盐与Li3PO4通过水热法制备LiFePO4,制得的LiFePO4材料表现出良好的电化学性能。

     

    Abstract: A high-value recycling method was introduced for spent lithium iron phosphate (LFP) cathode materials. Fe, P, and Li elements were recovered in the forms of FeSO4, FePO4, and Li3PO4, respectively. The recycling yield of Li recovered in the form of Li3PO4 reached 93%. The recycling process was free of phosphoric acid and phosphate and involved five steps: ① dissolving the waste lithium iron phosphate cathode material with sulfuric acid; ② recrystallizing more than one-third of Fe2+ ions as FeSO4; ③ oxidizing the remaining Fe2+ ions and adjusting the pH value of the solution to 2.0 ~ 3.0 to precipitate Fe2+ ions of FePO4, which can be used for solid-phase preparation of LiFePO4; ④ adjusting the pH value of the filtrate after separating FePO4 to 11.0, where the concentrations of Li+ ions and PO43- ions met the precipitation conditions to precipitate Li3PO4; ⑤ using the obtained ferrous salt and Li3PO4 to prepare LiFePO4 by hydrothermal methods, with the resulting LiFePO4 exhibiting good electrochemical performance.

     

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