| At present,ternary?NCM?lithium ion batteries have been widely used in consumer electronics products.Due to the limited cycle life of lithium-ion batteries,a large number of spent lithium-ion batteries have been produced,and study on recycling spent lithium-ion batteries is still in the development stage in China.In order to solve the problem of lithium ion battery recovery,this paper optimizes the process parameters of alkaline leaching agent [NH3·H2O+?NH4?2SO4+Na2SO3] and acid leaching agent [H2SO4+H<sub>2O2] leaching spent ternary lithium ion battery cathode material,using chemical precipitation.The method comprises the steps of separating and recovering nickel-cobalt-manganese,characterizing the phase structure and microstructure of the recovered product,and determining the material composition of the recovered product.H2SO4 and H<sub>2O2 were used to reduce acid leaching of waste ternary lithium ion battery cathode materials.The orthogonal experiment and single factor experiment were used to optimize the process parameters of reducing acid leaching.The best experiment parameter for leaching the cathode material of spent ternary lithium ion battery with H2SO4 and H<sub>2O2 was determined.The results show that 98.99% nickel,98.76% cobalt,and 98.31% manganese in the positive electrode material are transferred to the liquid phase as +2 valent metal ions.The cathode material of the spent ternary lithium ion battery was firstly leached with NH3·H2O+?NH4?2SO4+Na2SO3.The orthogonal experimental and single factor experiments were used to optimize the leaching process parameters,and the optimal experimental parameters of NH3·H2O+?NH4?2SO4+Na2SO3 leaching spent ternary lithium ion battery cathode materials were determined.The results show that 97.25% nickel and 93.05% cobalt in the positive electrode material are transferred to the liquid phase with nickel ammonia and cobalt ammonia complex.The alkali leaching residue was subjected to acid leaching using H2SO4 and H<sub>2O2,and manganese was present in the secondary leaching solution as Mn2+.The metal ion solution leached by H2SO4+H<sub>2O2 and NH3·H2O +?NH4?2SO4 +Na2SO3 was used as a raw material,and nickel,cobalt and manganese were separated and recovered by chemical precipitation.Optimize the parameters such as hydrogen peroxide dosage,reaction temperature and solution p H value during the process of recovering manganese.Using NH4HCO3 as a precipitant,a manganese recovery product was obtained.The phase structure and micromorphology of the recovered product were characterized by XRD and SEM,and manganese was recovered in the form of manganese carbonate.The solution after selective precipitation of Mn2+ is used as a raw material,and nickel cobalt is separated by chemical precipitation.Optimize the parameters such as the amount of EDTA added,the time of ammonia distillation,and the amount of sodium hydroxide added during the process of adding alkali steam.Using?NH4?2C2O4 as a precipitant,the p H value of the solution and the amount of ammonium oxalate added during the precipitation of Co2+ were optimized to obtain a cobalt recovery product.The phase structure and micromorphology of the recovered product were characterized by XRD and SEM,and cobalt was recovered in the form of cobalt oxalate.The solution containing Ni-EDTA was treated by the Fenton method,and the nickel recovered product was characterized by XRD,and the nickel was recovered as Ni2Fe2O4.Finally,the economic cost of recovering nickel-cobalt-manganese in the cathode material of spent ternary lithium-ion battery was analyzed.It was found that the cost of recovering nickel-cobalt-manganese in the cathode material of spent ternary battery in acid material was lower than that in the alkaline material recycling spent ternary battery cathode material.The cost of nickel-cobalt-manganese is expected to be applied in the lithium ion battery recycling process. |
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