Research On Recovery And Utilization Of Electrolyte For Spent Lithium-Ion Battery

With the booming development of electric vehicle industry,the number of lithium-ion batteries（LIBs）is increasing,and the number of spent LIBs is increasing year by year.There are not only valuable metal components but also a lot of organic electrolyte in spent LIBs.These valuable materials in electrolyte are highly flammable and explosive,and the toxic components containing fluorine produced by decomposition pollute the environment,which has become a bottleneck restricting the green recycling of spent LIBs.It is of great significance to promote the sustainable development of LIBs recycling industry to realize the efficient recovery and rational utilization of spent electrolyte.In this paper,the spent electrolyte as the research object.Based on thermodynamic calculation,developed vacuum distillation separation technology to recovery the spent electrolyte organic solvent.Lithium in spent electrolyte is recovered by precipitation method.The electrochemical performance of electrolyte prepared with reclaimed solvent was investigated,which provided a reference for the comprehensive recovery and utilization of electrolyte in spent LIBs.The main contents are as follows:（1）According to thermodynamic calculation,the separation coefficient of ethylene carbonate（EC）and dimethyl carbonate（DMC）,the separation coefficient of EC and diethyl carbonate（DEC）is much higher than 1,so DMC and DEC can be separated from the electrolyte.However,the separation coefficient of DMC and diethyl carbonate DEC was close to 1,so the mixture of DMC and DEC was recovered by vacuum decompression distillation.Under the optimal conditions of distillation temperature 130°C,distillation time 120 minutes,vacuum degree 0.09 MPa,magnetic stirring speed 435 r/min,the recoveries were100%and 79.40%,respectively.（2）The lithium resource in electrolyte can be recovered as Li₂CO₃by adding 1.4 times of excess sodium carbonate,and 92.45%purity and86.93%recovery can be achieved.（3）According to the formula of commercial electrolyte,recycled electrolyte was synthesized from recycled products.The Li/graphite button battery with regenerated electrolyte has an initial discharge capacity of 377.9 m Ah/g at a low current rate of 0.1C.After 100 cycles,its performance is improved to 392.1 m Ah/g,and the charge-discharge cycle efficiency of 99.5%or more is maintained.