Efficient Leaching Of Valuable Metals From LiCoO₂ Cathode Material Of Spent Lithium-ion Batteries With Citric Acid Reducing System

Currently,with the rapid development of the economy,society,and people's living standards,the production and use of lithium-ion batteries have been continuously increasing,and the application fields have become more and more widespread.However,while bringing convenience to people's lives,it has also caused many environmental problems and waste of resources problem.Recycling of valuable metals from spent Lithium-ion batteries?LIBs?appears inevitable for both environmental protection and resource recovery.In this study,the spent LIBs were first discharged and disassembled,and a variety of treatment methods?including organic solvent treatment,acid or alkali dissolution,crushing treatment,heat treatment?were used to separate the positive active materials and current collectors of spent lithium-ion batteries.Finally,heat treatment methods were used to separate and remove the binder and conductive agent from the active materials.For the leaching of spent lithium-ion batteries,an efficient hydrometallurgical leaching of Li and Co from the spent LIBs cathode materials by the coexistence system containing citric acid and sodium thiosulfate?Na₂S₂O₃?was explored.The effects of citric acid concentration,Na₂S₂O₃ concentration,leaching time,solid/liquid?S/L?ratio and temperature were also examined,and the factors except for S/L ratio,had positive effects on the extraction of Co and Li.Then the influence of multiple factors on the leaching of Co and Li was studied using Design-Expert 8.0.6.1 software,and response surface analysis was performed to optimize the optimal reaction conditions.According to the actual conditions,the optimum conditions are the concentration of citric acid 1.2mol/L,the concentration of sodium thiosulfate 0.3mol/L,the leaching time 35min,the solid-liquid ratio 20g/L,and the leaching temperature of 70?.Under these conditions,the leaching rate of cobalt is more than 99%,and the leaching rate of lithium is close to 100%in this coexistence system containing citric acid and sodium thiosulfate.The total chemical reaction of the leaching process is put forward.The characterization analysis conducted by XRD,SEM and ion chromatography revealed the reaction mechanism,and verified that the purer sulfur could be obtained as a by-product,and also SO₂ produced and easily collected as a raw material for sulfuric acid.The chemical reaction equation conforms to the principle of electron conservation,and it is considered that the proposed chemical reaction formula is established.Compare this system with the existing inorganic system from the aspects of reaction rate and economic value to highlight its advantages.It shows that the system is simple,low cost,high efficiency and high value,so it can consider further commercial application..