Lactic acid-assisted complexation for enhanced lithium extraction and its application to spent LIBs

A novel approach for complexing lithium with lactic acid to enhance extraction efficiency and its application to spent LIBs was proposed in this study. Key parameters influencing the extraction were systematically examined, including lactic acid concentration, pH of the aqueous phase, concentration of extractant, diluent selection, phase ratio between organic and aqueous phase, and stripping efficiency. Lithium extraction showed a remarkable improvement, rising from 16% to 43%, as the lactic acid concentration enhanced from 0.01 mol∙L‒1 to 1.0 mol∙L‒1. This was achieved using D2EHPA (0.1 mol∙L‒1) at a maintained pH of 6.5. Maximum lithium extraction of 84.5% was observed at an O/A ratio of 5:1. Kerosene was a suitable diluent found from the different diluents employed for extraction. The 0.1 mol∙L‒1 D2EHPA exhibited a lithium loading capacity of 0.084 g∙L‒1. This optimized process was further extended to recover Li from waste LIB. 99.9% of Co and 91.2% of Li were extracted in three stages of cross-current extraction. Na2CO3 was utilized as a stripping agent for separating Co and Li. Using 2.5 mol∙L‒1 Na2CO3, almost 90% of the Li was precipitated as Li2CO3, and 99.8% of the Co was recovered.