Recovery And Reuse Of Electrode Waste LiNi_0.5Co_0.2Mn_0.3O₂

Lithium ion batteries due to the characteristics of long cycle life,high working voltage,safety performance is high,the advantages of environmental friendly has been widely used,but the lithium ion battery production,resulting in a large number of the electrodes of a battery has not been assembled into waste produced,if not be recycled,can cause harm to the environment can cause both waste of resources,in the method of lithium ion battery recycling,mainly concentrated in the old battery contains metal recycling,the recycling method is relatively complicated,Therefore,this paper will focus on the simplification of the recovery process of electrode waste LiNi_0.5Co_0.2Mn_0.3O₂ and mainly divide it into three parts.（1）To provide raw materials for the next step of recycling,the best conditions for electrode waste pretreatment process and removal of binder PVDF are studied.The influence of factors such as solvent type,ultrasonic time,and the order of ultrasonic and agitation on the peeling efficiency were studied by using the controlled variable method.Subsequently,the obtained organic solvent filtrate was calcined by centrifugation and then subjected to thermogravimetric analysis and infrared spectrum characterization to determine the optimal calcination temperature for removing the binder.The best peeling efficiency can reach 93%under the condition of using N-methylpyrrolidone（NMP）as a solvent,stirring first and then ultrasonic cleaning,stirring time 60 min,stirring temperature 60℃,solid-liquid ratio1:30 g·mL^-1,and ultrasonic time 120 min.PVDF can be effectively removed at a calcination temperature of 800℃（2）The best calcination temperature of the organic solvent filtrate（obtained from the NMP solution dissolved with cathode material removed by extraction and filtration of aluminum foil）was determined through the electrochemical properties of the material（R-LNCM）prepared after calcination at different temperatures for 3 h.Experiments show that the cathode material has a good lamellar structure and cation mixing degree at 800℃,and has good electrochemical performance.In the voltage range of 2.75-4.5 V and a rate of 0.2 C,the initial discharge capacity is 164.2mAh·g^-1,after 50 cycles,the discharge capacity is 132.4 mAh·g^-1,and the capacity retention rate is 80.6%.This is because the material particles calcined at 800℃have a uniform distribution and small particles on the surface,which increases the contact area between the material and the electrolyte.（3）The optimal conditions for acid-dissolving the cathode material calcined at800℃were studied（R-LNCM）,and the ternary materials were re-prepared by using the acid-dissolved filtrate and acetate as raw materials for comparison.The preparation of the ternary material by directly using the acid-dissolved filtrate avoids complicated metal separation steps,and the operation is simpler and more efficient.The experiments show that the optimal acid can be reach 99%under the conditions of citric acid concentration of 1.0 mol·L^-1,hydrogen peroxide addition amount of 2vol%,solid-liquid ratio of 30 g·L^-1,reaction time of 80 min,and reaction temperature of 80℃.The ternary material regenerated under the best conditions by mechanochemical method has an initial discharge capacity of 149.9 mAh·g^-1,and after 50 cycles,the discharge capacity is 138.7 mAh·g^-1,and the capacity retention rate is 92.5%.The ternary material regenerated under the best conditions by the sol-gel method has an initial discharge capacity of 158.9 mAh·g^-1,and after 50 cycles,the discharge capacity is 132.4 mAh·g^-1,and the capacity retention rate is 83.3%.The electrochemical performance of recycled materials and synthetic materials prepared by the two methods is not much different.The particle size and distribution of the recycled material prepared by the mechanochemical method are small and uniform,which improves the utilization rate of lithium ions.Therefore,the ternary material prepared by the mechanochemical method has better electrochemical performance.