Selective Recovery of Critical Metals from Spent Lithium-Ion Batteries through Direct Bioleaching Using

The rapid growth of electrified transportation and the widespread adoption of portable electronic devices have significantly increased the demand for efficient energy storage systems. Lithium-ion (Li-ion) batteries are known for having a higher energy density and a longer cycle life than other types of batteries, making them the most reliable and long-lasting choice. However, the escalating accumulation of end-of-life Li-ion batteries has introduced notable environmental and economic challenges. The intricate composition of these batteries complicates the selective recovery of valuable metals. Traditional recycling techniques, including pyrometallurgy and hydrometallurgy, although effective, are associated with high operational costs, substantial energy consumption, and the generation of secondary waste. As a sustainable alternative, bioleaching utilizes specific microorganisms to mediate the selective solubilization of metals from complex battery matrices through their metabolic activities. In this study, direct bioleaching of lithium-ion (Li-ion) battery black mass was performed over a seven-day period employing the mixotrophic bacterium Citrobacter freundii strain SKC-4. Following the bioleaching process, notable metal recoveries were achieved, with extraction efficiencies of 41.4% for lithium (Li), 2.4% for nickel (Ni), 2.9% for cobalt (Co), 9% for copper (Cu), 7.3% for manganese (Mn), and 6.7% for aluminum (Al). These findings demonstrate the efficacy of Citrobacter freundii in the direct bioleaching of spent Li-ion battery black mass and highlight its potential as an environmentally sustainable approach for the selective recovery of valuable metals, contributing to the advancement of circular economy practices in battery recycling.