Efficient and Green Recovery of Lithium from Spent Lithium-Ion Batteries Based on a Multipotential Field Membrane Process Intensification

Advancements in recycling technologies for spent lithium-ion batteries (LIBs) are moving toward environmentally friendly and lower carbon approaches. This study presents a novel method for lithium extraction from spent LIBs based on a multipotential field membrane coupling process involving nanofiltration (NF), reverse osmosis (RO), and selective electrodialysis (SED). Lithium is extracted from the leaching liquor of spent LIBs containing multiple ions by using NF. The combined effects of the Donnan steric hindrance and dielectric exclusion determine the retention rates of each ion. Divalent ions such as Ni2+, Co2+, and Mn2+ experience stronger repulsion during the mass transfer process, resulting in rejection rates all above 98%, which is advantageous for the selective separation of lithium ions, and the recovery rate of lithium in the NF stage reached 96.02%. Considering the characteristics of the leaching liquor, which is acidic and high in chloride, the DK membrane is selected for its superior comprehensive performance from the three commercial NF membranes, with a particular focus on assessing the long-term separation performance stability and tolerance. Finally, the NF separation is coupled with the RO concentration and SED concentration processes to achieve efficient separation and enrichment of lithium. The lithium-ion concentration reached 15.23 g/L, and a Li2CO3 product with a main content of 99.82% is prepared, providing an efficient and environmentally friendly method for lithium recovery from spent LIBs.