Kinetic optimization in green metal recovery: Citric acid vs glycine for sustainable Li-ion battery recycling.

Due to the natural depletion and potential toxicity of some metals in lithium ion batteries (LIB), it is getting important to recover valuable metals such as Li and Co from spent LIBs. This study used citric acid or glycine to leach the valuable metals from cathode materials of these spent LIBs such as lithium iron phosphate (LFP) or lithium manganese oxide (LMO) batteries. The effects of concentrations of the citric acid or glycine, solid-liquid ratio, and H2O2 on the leaching rate of valuable metals were investigated by a batch experiment. The leached Mn2 + and Li+ in the solution were recovered effectively by precipitation of MnO2 and Li3PO4 by KMnO4 and Na3PO4 with the recovery rate of Mn (95.02 % from LMO) and Li (94.23 %, and 95.29 % from LFP or LMO, respectively). Moreover, citric acid or glycine are shown to be acid leachants for recovering metals from spent LIBs.