Low-Temperature Molten-Salt-Assisted Recovery of Valuable Metals from Spent Lithium-Ion Batteries

A novel and environmentally friendly process for utilizing spent lithium-ion batteries based on salt roasting is proposed. The separated cathode material is roasted with NH4Cl as a fluxing agent. During this process, Li and Co are converted to chlorides due to the release of HCl and NH3 from the reaction of NH4Cl, with LiCoO2. These chloride salts are readily soluble in water. The reaction parameters, including roasting temperature, time, and LiCoO2/NH4Cl mass ratio, were investigated in detail. The results showed that more than 99% Co and Li were recovered under optimum conditions: temperature of 350 °C, reaction time of 20 min, and a LiCoO2/NH4Cl mass ratio of 1:2. A possible reaction mechanism between LiCoO2 and NH4Cl is proposed based on thermodynamic, X-ray diffraction, and X-ray photoelectron spectroscopy analyses. The treatment of other spent lithium-ion battery cathode materials, such as LiMn2O4 and LiCo1/3Mn1/3Ni1/3O2, verified the effectiveness of the method for recovering the valuable metals.