Sustainable Recovery of Critical Metals from Waste Lithium-Ion Batteries through Bio-electrochemical System

The growing amount of spent lithium-ion batteries (LiBs) has unlocked the necessity of recycling technologies that are sustainable and environmentally friendly for the recovery of critical metals. In this study, the microbial fuel cells (MFCs) were designed for metal recovery, in which microorganisms play a key role in recovering critical metals from LiBs through bio-electrochemical processes. The three different bacterial consortia (SC1, SC2, and SC3) were isolated and characterized, and belong to the Firmicutes phylum. Five two-chamber MFCs were designed and evaluated for their electrochemical performance and metal recovery efficiency. The results showed the variation of electricity generation and metal dissolution in all MFCs. The electrochemical performance of MFC-SC3 was the best with a maximum voltage of 268 mV, a maximum current of 2.68 mA, a maximum power of 801 mW/m² and a maximum current density of 2.98 A/m². In terms of metal recovery, MFC-SC2 had the best Li dissolution efficiency of 55.23%, and MFC-SC3 had better Co and Cu recovery efficiencies of 61.3% and 51.88%, respectively. The results highlight the potential of MFC technology to be a promising and sustainable solution for recovering valuable metals from spent LiBs and simultaneously generating bioelectricity, which aligns with the principles of the circular economy and green recycling.