The annual global volume of waste lithium-ion batteries (LIBs) has been increasing over years. Although solvent extraction method seems well developed, the separation factor between cobalt and nickel is still relatively low—only 72 when applying conventional continuous-countercurrent extraction. In this study, we improved the separation factor of cobalt and nickel by complexation-assisted solvent extraction. Before solvent extraction procedure, leaching kinetic of Li, Ni, Co and Mn was studied and can be explained by the Avrami equation. Leached residues were also investigated by SEM and XRD. Operation parameters of complexation-assisted solvent extraction were examined, including volume ratio of extractant to diluent, types of diluent, type of complexing reagent, extractant saponification percentage and volume ratio of organic phase to aqueous phase. The optimal separation factor of complexation-assisted solvent extraction could be improved to 372, which is five times that of conventional solvent extraction. The separation tendency would be interpreted by the relationship between extraction equilibrium pH and log distribution coefficient.

中文翻译：

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络合辅助溶剂萃取从NMC型锂离子电池正极材料中高效回收钴和镍

多年来，全球每年废弃锂离子电池（LIB）的数量一直在增加。尽管溶剂萃取方法似乎发展得很好，但钴和镍之间的分离系数仍然相对较低-在应用常规连续逆流萃取时仅为72。在这项研究中，我们通过络合辅助溶剂萃取提高了钴和镍的分离系数。在溶剂萃取过程之前，研究了Li，Ni，Co和Mn的浸出动力学，并且可以用Avrami方程解释。还通过SEM和XRD研究了浸出的残留物。检查了络合辅助溶剂萃取的操作参数，包括萃取剂与稀释剂的体积比，稀释剂的类型，络合剂的类型，萃取剂的皂化百分比和有机相与水相的体积比。络合辅助溶剂萃取的最佳分离因子可以提高到372，是传统溶剂萃取的5倍。分离趋势将通过萃取平衡pH和对数分布系数之间的关系来解释。