Study On Recovery Of Valuable Metals From Cathode Material Of The Spent Lithium-ion Battery

With the continuous improvement of China’s economic strength,lithium-ion battery has become an indispensable product in the energy storage material market.Lithium ion battery is widely used in electronic equipment,military,electrical and other fields because of its high specific energy,safety and other good performance.Hence a large number of waste lithium-ion batteries have been produced and the treatment and recycling of waste lithium-ion batteries are of great significance for the comprehensive utilization of resources and environmental protection.The elements of nickel and cobalt in the cathode materials of waste lithium-ion batteries（18650）were recovered by hydrometallurgical methods in paper.Firstly,the collector and active material of the cathode electrode material were separated by selective dissolution method,then the active material was leached with sulfuric acid plus reducing agent,and finally the valuable metals in the electrode material were recovered directly from the leaching solution by hydrothermal synthesis-calcination method.The electrode materials,phase composition,morphology and element content of the recovered products were analyzed by X Ray Diffractometer（XRD）,Scanning Electron Microscope（SEM）and Energy Dispersive Spectrometer（EDS）.The concentration of metal ions in leaching solution was analyzed by chemical titration and instrumental determination.The results show that the cathode electrode materials of the waste lithium battery were selectively dissolved in a self-prepared solution to separate the positive active material and the current collector.The effects of the amount of solvent and the dissolution time on the removal rate of the cathode active material were investigated.When the solvent dosage was 150 m L and the dissolving time was 60 min,the removal rate of the cathode active material was more than 95%.The effects of sulfuric acid concentration,reductant volume fraction,leaching temperature and time,solid-liquid ratio on metal leaching rate were studied.The results showed that under the conditions of CH2SO4=2.5 mol / L,H₂O₂（v/v%）=10%,T=80 ℃,t=80 min and S/L=1:14 g/m L,the leaching rates of Ni,Co and Mn were 93.82%,99.53% and 14.88% respectively.Nickel cobaltic acid was prepared from nickel sulfate and cobalt sulfate solution by hydrothermal synthesis-calcination method.The effects of precipitant type,hydrothermal temperature,calcination temperature and molar ratio of nickel and cobalt on the morphology and phase of NiCo₂O₄ were studied.The results showed that when the molar ratio of nickel and cobalt was 1:2.0,hydrothermal temperature was 160 ℃ 180 ℃,calcination temperature was 450℃,the bar shape nickel cobaltic acid could be prepared by calcining with oxygen.NiCo₂O₄ was prepared from the leach solution at 120℃.The process of selective dissolution-leaching-hydrothermal synthesis-calcination can be used to treat the waste cathode materials of lithium battery,then NiCo₂O₄ materials could be obtained as the final product,which realized the comprehensive utilization of waste electrode materials.