Reductive Dissolution\nof NCM Cathode through Anaerobic\nRespiration by Shewanella putrefaciens

The consumption of lithium-ion batteries (LIBs) has considerably\nincreased over the past decade, leading to a rapid increase in the\nnumber of spent LIBs. Exposing spent LIBs to the environment can cause\nserious environmental harm; however, there is a lack of experimentally\nobtained information regarding the environmental impacts of abandoned\ncathode materials. Here, we report the interactions between Shewanella putrefaciens, a microorganism commonly\nfound in diverse low-oxygen natural settings, and LiNi<sub>0.6</sub>Co<sub>0.2</sub>Mn<sub>0.2</sub>O<sub>2</sub> (NCM622) under anaerobic\nconditions. We present compelling evidence that the anaerobic respiration\nof Shewanella putrefaciens triggers\n∼59 and ∼78% dissolution of 0.2 g/L pristine and spent\nNCM622, respectively. We observed that Shewanella putrefaciens interacted with the pristine and the spent NCM622 under anaerobic\nconditions at a neutral pH and room temperature and induced the reduction\nof Ni, Co, and Mn, resulting in the subsequent dissolution of Li,\nNi, Co, and Mn. Moreover, we found that secondary mineralization occurred\non the surface of reacted NCM622. These findings not only shed light\non the substantial impact of microbial respiration on the fate of\ndiscarded cathode materials in anaerobic environments but also reveal\nthe potential for sustainable bioleaching of cathodes in spent LIBs.