Biotreatment for the spent lithium-ion battery in a three-module integrated microbial-fuel-cell recycling system

Abstract

A bio-electrochemically (BE) recycling platform was assembled to recover Li and Co from the cathodic materials of spent LIBs in one integrated system. The BE platform consists of three microbial-fuel-cell (MFC) subsystems, including MFC-A, MFC-B, and MFC-C. Co and Li were smoothly recovered from the cathodic materials in the assembled platform. The initial pH and the loading ratios of LiCoO2 both significantly influenced the leaching efficiencies of Li and Co in MFC-A. Approximately 45% Li and 93% Co were simultaneously released through the reduction of LiCoO2 at the initial pH of 1 and the loading ratios of LiCoO2 of 0.2 g/L. The (NH4)2C2O4-modified granular activated carbons (GAC) with a thickness of 1.5 cm was favorably stacked adjacent to the cathode of the MFC-B system. About 98% of removal efficiency (RECo1) and 96% of recovery efficiency (RECo2) of Co were achieved in MFC-B under optimum conditions. The dosing concentration of Li+ lower than 2 mg/L and the (NH4)2CO3 of 0.01–0.02 M were conducive to enhancing the recovery of Li from raffinate and guaranteed the higher power output and coulombic efficiencies in MFC-C. The continuous release of CO2 caused by exoelectrogenic microorganisms on the biofilm facilitated the precipitation of Li2CO3.