Research On Green Recycling And Reuse Of Waste Ternary Lithium-Ion Batteries

With the development of new energy vehicles,aerospace and other industries,lithium-ion batteries have occupied more and more market shares.A large number of lithium-ion batteries have been scrapped due to life decay and internal breakage,which causes waste of resources and environmental pollution.There is a large amount of Ni,Co,Mn,and Li ions in cathode materials which have high recycling value.Currently,the main method for recycling is hydrometallurgical,which used hydrogen peroxide as the reducing agent.However,hydrogen peroxide had corrosive and bad stability,therefore,it is important to find a stable reducing agent,and it is beneficial for green recycling of cathode materials in lithium-ion batteries.This research focuses on waste ternary cathode materials and builds a glucose reduction enhanced inorganic acid leaching system according to the dynamics and other theories.Besides,chemical co-precipitation method is used to recover valuable metal ions and solid phase reaction method is used to research the regeneration process of cathode materials.This paper presents a potential solution for the industrial application of recycling valuable metals from waste cathode materials.The results showed that:（1）The single variable method was used to optimize the acid leaching process.The leaching rates of valuable metals were all above 95%in phosphoric acid leaching system under the optimal process conditions,and those in sulfuric acid leaching system were all above 97%.The Avrami equation and Arrhenius equation are used to fit the reaction kinetics of the leaching process,the results showed that the leaching process was controlled by interfacial chemical reaction.Besides,the decomposition process of glucose in the leaching system was measured.The glucose was decomposed into tartaric acid,glucaric acid,tartornic acid,glyoxylic acid,oxalic acid,formic acid and carbon dioxide through the aldose oxidation reaction,which played a reducing role.This also increased the acid concentration in the leaching system.（2）The chemical co-precipitation method was used to separate and purify valuable metals in the leaching solution.The precipitation rates of Ni,Co and Mn were all above95%when used the oxalic acid precipitation method.The Mn C₂O₄ was unstable produced by oxalic acid co-precipitation method,so the alkali co-precipitation method was used to recover the valuable metals in the leaching solution.The precipitation rate of Ni,Co and Mn by alkali co-precipitation was above 96%.The lithium-ions in the solution are recovered in the form of lithium carbonate and its purity rubric reached99.15%.The sodium sulfate crystal were obtain through filtrate of condensed and evaporated after alkali co-precipitation,and the ammonia water can be recycled used.（3）The solid phase reaction method was used to regenerate cathode materials of ternary lithium-ion battery.Under the optimal technological parameters,the I003/I104value of the cathode material was 1.48,indicating that it has a small cationic mixing degree.Its c/a value was 4.97,indicating that it has excellent layered structure.The initial charge-discharge capacity of the regenerated cathode materials reached164.1mAh·g^-1 and 143.8 mAh·g^-1 at 0.2 C rate,and the coulomb efficiency was 87.65%.