Metal coordination combining with electrodialysis for one-step separation of valuable metals from spent lithium-ion batteries

Efficient recycling of valuable metals from spent lithium-ion batteries (LIBs) is essential for the circular economy and ecological environment. However, the simultaneous separation and recovery of multiple metal ions face a huge challenge due to their similar physicochemical properties. Herein, we propose metal coordination combing with electrodialysis to achieve one-step separation of lithium, cobalt, and nickel. By regulating the ligands and ligand concentration, the Co2+ selectively coordinates with ligand to form anionic complex, which passes through the home-made anionic polymer inclusion membrane under electric field. Li+ passes through the monovalent cationic exchange membrane, whereas the Ni2+ is retained in the feed solution, thereby achieving the one-step separation of metal ions. When using NH4SCN as ligand, the transport flux of Li+ and Co(SCN)42- reaches around 25.0 µmol m−2 s−1 and 12.7 µmol m−2 s−1, respectively. Meanwhile, the separation efficiency of lithium and cobalt is 80 % and 95 %, respectively at the NH4SCN concentration of 0.1 M and current density of 10 mA/cm2. Additionally, sustainable solar energy is successfully applied to drive the electrodialysis system, and the purity of lithium, cobalt, and nickel is as high as 94.3 %, ∼100 %, and 99.2 %, respectively, demonstrating great potential in decreasing energy consumption. This work which applies metal coordination combining with electrodialysis for one-step separation of lithium, cobalt, and nickel, provides a promising candidate for the recycling of valuable metals from spent LIBs.