Achieving Reusability of Leachate for Selective Recycling of Multiple Metal Elements From Spent NCM Based on Precipitant‐Free Preferential Extraction of Nickel

For treating huge amount of retired lithium‐ion batteries in the coming years, realizing reusability of leachate for the selective recovery of valuable metal elements from spent high‐nickel NCM cathodes is highly desirable, yet it is currently limited by the irreversible degradation of leachate during conventional precipitation processes. Herein, we report the successful realization of reusability for leachate during the selective extraction of transition metal elements using a ChCl:FA DES leachate system. After leaching spent NCM, nickel element can be selectively precipitated by simply cooling. This unique property of reversibly controllable solubility is enabled by the competitive interplay between DES ligands and trace water molecules around the nickel atom. Consequently, Ni elements could be preferentially extracted while Co and Mn could be enriched without adding alkaline precipitating agents, thus enabling leachate reusability. This strategy provides a high recovery yields of 98.73%, 98.09%, and 90.50% for Ni, Co, and Mn respectively. No observable degradation of leachate was observed after three extraction cycles. Our strategy for realizing reusability of leachate for selective recovery of multiple metal elements is expected to offer a general solution with high economic and environmental value for recycling of spent batteries.