Bioleaching of valuable metals from three cathode active materials comprising lithium nickel cobalt manganese (NCM) oxide using indigenous microorganisms

Recently, bioleaching has been studied for the metal recovery of lithium (Li), nickel (Ni), cobalt (Co), and manganese (Mn) from spent lithium-ion batteries. However, further work should be conducted to improve the metals recovery using efficient microorganisms and to investigate the effects of metal composition on black mass due to its heterogeneity. Our study reports bioleaching-mediated recovery of valuable metals Li, Ni, Co, and Mn from three typical LiNi_xCo_yMn_1−x−yO₂ (NCM) cathode active materials with different compositions (NCM111, NCM523, and NCM622) using five bacterial strains (N10, P6, P7, N4, and F-O5) isolated from abandoned mines. Compared with the control (Acidithiobacillus ferrooxidans, KCTC4516) and blank conditions, the metal leaching efficiency of Li, Ni, Co, and Mn from NCM111 reached above 95 % using the N10 and P7 strains for 24 h at a pulp density of 10 g/L. Moreover, the lower leaching efficiency of metals using NCM523 and NCM622 was observed. A higher concentration of nickel in the leachate negatively influenced the bacterial activities. This study elucidates the bioleaching potential of isolated single strains for the extraction of metals from NCM. Additionally, it emphasizes the crucial role of Ni-adapted microorganisms in efficiently extracting metals from NCM with high Ni-content.