Abstract: With the continuous expansion of various electronic equipment markets, lithium-ion batteries (LIBs) are widely used in numerous fields. This trend has also brought about the challenge of recycling a growing number of retired and spent LIBs. Although traditional pyrometallurgical and hydrometallurgical recovery technologies have become relatively mature, several issues remain to be addressed. For example, pyrometallurgical processes suffer from relatively low metal recovery efficiencies, while conventional acid/alkali leaching processes often require the addition of extra precipitants to recover certain metals. In this work, a new strategy is proposed for the clean and efficient recovery of Li and Co from spent LiCoO2 cathode materials using a ChCl-OA-H2O deep eutectic solvent (DES). The method involves the selective separation of Co as cobalt oxalate (CoC2O4?2H2O) via preferential precipitation, followed by the direct recovery of Li by adjusting the water content. The entire recovery process requires no additional reagents and is both simple and environmentally friendly. Under optimal conditions (molar ratio 1∶1∶8, solid-liquid ratio 100 g/L), the leaching efficiency of Li can reach 99.4%, and the recovery efficiencies of Li and Co are 88.3% and 97.8%, respectively, demonstrating excellent metal separation and recovery performance. Furthermore, the DES system exhibited good cycling stability, maintaining Li and Co recovery efficiencies of 78.1% and 92.8% after six cycles, which highlights the sustainability and economic potential of the process for practical applications. This study not only provides an efficient and low-pollution technological pathway for battery recycling, but also offers theoretical support and practical evidence for the sustainable cycling of resources, demonstrating significant environmental benefits and promising industrial application potential.

Key words: spent lithium-ion batteries, clean and efficient recovery, deep eutectics solvents, H2O-regulated strategy, high solid-liquid ratio

摘要： 本工作提出一种在氯化胆碱-草酸-水低共熔溶剂(ChCl-OA-H2O DES)中清洁高效回收废旧钴酸锂(LiCoO2)正极材料中锂和钴的新策略。该策略首先使钴以草酸钴(CoC2O4?2H2O)的形式优先沉淀实现选择性分离，随后通过调节体系水含量实现锂的直接回收，整个回收过程无需须添加沉淀剂，操作简单。在浸出体系摩尔比为1∶1∶8、固液比为100 g/L的最优条件下，锂浸出率可达99.4%，锂和钴的回收率分别达到88.3%和97.8%，展现出该方法优异的金属分离与回收效果。此外，再生后DES的浸出和回收性能表明，经6次再生循环后，锂、钴回收率仍可维持在78.1%和92.8%，证实该溶剂体系具备良好的循环稳定性。本研究为废旧锂离子电池的金属回收提供了一条环境友好、操作便捷且经济可行的途径，在实际应用中具有可推广性。

关键词: 废旧锂离子电池, 清洁高效回收, 低共熔溶剂, 水调控策略, 高固液比