Discharge Properties Of Waste Lithium Ion Batteries And Oxygen-Free Roasting To Recycle Electrode Materials

With the rapid development of electronic technology and electric vehicle industry,the market share of lithium-ion batteries in the world continues to expand.However the limited charge and discharge cycle life and rapid replacement rate caused a large amount of waste lithium-ion batteries.These abandoned lithium-ion batteries contain large amounts of heavy metals,electrolyte and other organic substances.These materials entering into the environment will bring serious soil and groundwater pollution as well as safety hazards.On the other hand,these batteries"garbage"is a kind of valuable resource,containing valuable metal content more than the natural concentration of concentrate.At present,the traditional recycling process is the hydrometallurgical technology,easily leading to secondary pollution.So the effective and environmental-friendly recycling of waste lithium-ion battery metal resources put great significance on the sustainable development.The first and forecast procedure is discharge pretreatment of waste lithium-ion batteries.The new environment-friendly and green discharge system is explored for the negative environmental effects of the pretreatment of NaCl solution discharge,which is currently widely used.The discharge rate and corrosion degree of waste Li-ion battery in different system were compared.And comprehensive discharge effect and the environmental impact were considered to determine the appropriate discharge system is 0.8mol/LFeSO₄ solution.Also a batch of high efficiency continuous semi-enclosed lithium ion battery discharge device was designed.It was achieved that waste lithium-ion battery pretreatment process was conducted safely and environmental-friendly.Waste lithium-ion battery electrode materials were roasting in oxygen-free condition.The feasibility and appropriate conditions of the high temperature reaction of anode materials were investigated.Then,the electrode materials were roasting under different reaction temperature,different atmosphere and different holding time.The products were mainly composed of unreacted graphite,metallic Co and Li₂CO₃.And the reaction mechanism was the same as deduction.The optimum reaction conditions for recovery of the reduced metal were obtained.According to the difference of physical properties,wet separation method was used as the effective separation of products.The optimum conditions for the recovery of Co are as follows:the electrode materials is roasting at 1000?,in nitrogen atmosphere with holding time of 60min.After wet magnetic separation,the recovery rate of metal Co is 97.15%The results show that the in-situ reduction method of oxygen-free roasting is simpler than that of hydrometallurgical process.And the effective recovery of electrode materials in green way was realized.