A Study on the Leaching Behavior of Li, Fe and P from Lithium Iron Phosphate Cathode Powder Using Deep Eutectic Solvents

With the increasing global demand for electric vehicles, the end-of-life battery market is rapidly expanding.Consequently, the separation and recovery of valuable resources from spent batteries have attracted increasing interest.Conventional hydrometallurgical recycling processes often cause environmental pollution; hence, environmentally benign processes utilizing green solvents have recently garnered significant attention.In this study, the leaching behaviors of the major elements in lithium iron phosphate cathode powder were investigated using deep eutectic solvents (DESs), which are emerging as eco-friendly alternatives.As comparative studies on various DESs using the same LFP feedstock are limited, five different DESs were evaluated in this work.Based on the experimental results, an optimal DES was selected, and selective leaching of lithium was achieved by optimizing the additives and reaction times.Inductively coupled plasma-optical emission spectrometry analysis indicated a lithium leaching efficiency of approximately 91% for choline chloride-ethylene glycol-based DES combined with K 2 S 2 O 8 as an oxidizing additive.In addition, phosphorus leaching was suppressed to approximately 3%, and iron was not leached, indicating a high lithium recovery efficiency and superior selectivity.Finally, the feasibility of selective lithium leaching using DESs as environmentally benign solvents was confirmed.