Recovery And Regeneration Of LiNi_0.6Co_0.2Mn_0.2O₂ From Spent Lithium-ion Batteries

Lithium-ion batteries（LIBs）have the advantages of low self-discharge,high specific capacity and high battery voltage,which can be widely used in electric vehicles,computers,communications,consumer electronics and energy storage.In recent years,the increase in demand for lithium batteries is obvious,followed by the production of a large number of waste batteries.These waste LIBs contain large amounts of heavy metals and organic compounds,which can cause a serious damage to human health and the environment,so they can’t be simply buried.In addition,due to the limitation of natural resources and the increasing demand for energy in the market,the valuable metals in the waste lithium batteries are in urgent need of recycling.In this paper,we take the waste cathode material as the research object,and propose a method to recover valuable metals from waste LiNi_0.6Co_0.2Mn_0.2O₂cathode powder.Then the cathode material LiNi_0.6Co_0.2Mn_0.2O₂is regenerated and re-synthesized by using these metal ions to realize the resource utilization of valuable metals in the waste LIBs.The effects of leaching conditions on the leaching efficiency of valuable metals and the electrochemical properties of the regenerated LiNi_0.6Co_0.2Mn_0.2O₂were investigated.The results show that in the leaching system composed of 6 mol·L^-1[NH₃]_Tand 0.2mol·L^-1sulfite,the leaching efficiency of Li,Ni,Co and Mn reaches the summit,98.46%,97.28%,96.52%and 95.83%,respectively,at the conditions of p H 10.5,20 g·L^-1solid-liquid ratio,140°C for 90 min.No matter how the leaching conditions change,the leaching efficiency of Al is very low（about 1%）.Due to the content of Al in the positive electrode powder is very low,the gross of Al in the leaching solution can be ignored.The precursor Ni_0.6Co_0.2Mn_0.2（OH）₂was prepared from the leaching solution by the combination of ammonia evaporation and co-precipitation,and then the cathode material LiNi_0.6Co_0.2Mn_0.2O₂was obtained by two-stage heating calcination.The prepared cathode material LiNi_0.6Co_0.2Mn_0.2O₂particles have uniform distribution and good crystal structure.At the current density of 0.1 C,the first charge-discharge specific capacitance is 190.7 and 174.5 m Ah·g^-1,respectively.After 100 cycles at the current density of 0.5 C,the discharge specific capacity is 139.3 m Ah·g^-1,and the capacity retention rate reaches92.19%.To sum up,the recycling process adopted in this paper can effectively recover the valuable metals from the waste LIBs and regenerate cathode materials at the same time,which simplifies the subsequent separation process,reduces the pollution of waste LIBs to the environment.and brings good economic benefits.