Gut microbiota-driven, acid-free recovery and upcycling of spent lithium-ion battery cathodes

The sustainability of lithium-ion battery recycling faces challenges due to the heavy reliance on corrosive acids in hydrometallurgy and traditional bioleaching. Here, a neutral-pH bio-metallurgical process using gut microbiota is reported for leaching spent Li(Ni0.5Co0.2Mn0.3)O2 cathodes. Under facultative anaerobic conditions, the microbial community adapts to enrich metal-tolerant and electroactive groups (e.g., Actinobacteriota, Desulfobacterota_I), allowing metal release through direct contact and extracellular electron transfer. Riboflavin, a known electron shuttle, improves yields to 99.3% for Li and 93.3% for Ni when supplemented. Significantly, the process leads to different fates for metal ions: Li and Ni remain soluble, while Co and Mn are reduced to form NH4(Co,Mn)PO4·H2O precipitates. This in situ phase separation simplifies downstream purification. The phosphate residues show excellent electrochemical performance, with a capacitance of 168 mF·cm−2 as supercapacitor electrodes. This method presents a green, robust, and adaptable approach for critical metal recycling.