A Study On Selective Extraction Of Valuable Metals And Refabrication Cathode Materials From Spent Lithium Ion Batteries

With the trend of technological innovation and the reduction of non-renewable energy consumption,electronic products and electric cars based of lithium-ion batteries as energy storage components have spurred rapidly.However,the typical life of lithium batteries is 3～5 years,resulting in the number of spent lithium batteries has been on the rise.The valuable metals,organic solvents and other components included in the spent lithium battery(LIB)areeasy to cause harm to human health and the environment.Meanwhile,Li and Co metals rich in such batteries are high value-added resourses.Therefore,exploring reasonable recycling methods to achieve green recycling reuse LIBs has become a research hotpot.This paper intends to adopt a mild leaching and simple separation system to ensure high metals leaching rates,and to conduct a targeted research on the recovery and reuse of different cathode materials.The main contents are as follows:(1)Though tartaric acid leaching the cathode material of LiNi0.5Co02Mn0.3O2,single-factor experiments can prove effects of metals under different conditions,and then the apparent activation energies of metals can be obtained by simulates and calculates dynamics for leaching process,clear and definite reaction mechanism and leaching behavior.The optimal leaching conditions are 0.6 mol/L C4H6O6,4 vol.%H2O2,40 mL/g,80℃ and 30 min,which makes the effective short-range separation of Li and transition metals,as well as the low concentration of tartaric acid reduces leaching costs,come true.These results show that the chemical reaction is the rate-controlling step during the tartaric acid leaching process and the leaching product exists in the form of C4H4O6 Me confirmed by XRD,XPS and other characteristics.(2)Re-leach the product incorporating transition metals obtained by tartaric acid leaching with slightly sulfuric acid to obtain the required metals salt solution,the new cathode material of LiNi1/3CO1/3Mn1/3O2 is resynthesized through carbonate co-precipitation method,and then electrochemical test is applied to analysis material properties.The results show that the obtained precursor of Co1/3Ni1/3Mn1/3CO3 has a regular morphology and high crystallinity crystal structure under the optimal precipitation conditions.By exploring different calcination temperatures and adding different lithium sources,the obtained optimal preparation conditions is to mix the precursor with Li2CO3,then calcine at 500℃ for 5 h,finally calcine at 90℃ for 12 h.The obtained material(LiNi1/3Co1/3Mn1/3O2)is characterized by XRD and SEM indicated structure integrity.At last,electrochemical characterization shows that the first discharge capacity is 159 mAh/g at 0.1 C,after 50 cycles at 0.5 C with the capacity retention of 97%.(3)Utilizing spent LiFePO4 as the primitive material and‘OH with strong oxidation,fenton system,taking place of the traditional acid leaching,is formed of the certain concentration of Fe2+and H2O2.Li is leached on liquid and Fe is oxidized of FePO4 so as to achieve selectively leach-separate at the same time.97.8%of Li can be extracted and less than 1%Fe can be dissolved under optimal conditions of 1 g/L LiFePO4,30 mmol/L H2O2,0.5 mmol/L FeSO4,40℃ and 30 min,Then the precipitation is proved as FePO4 by XRD and XPS physical characterization.Kinetic analysis shows that the leaching behavior of Li is one model of chemical reaction control.With leaching products as raw materials,through carbon reduction and optimization of parameters of different calcine temperatures and carbon content,the appropriate temperature is 750℃,25%glucose and addition amount of 5%Li2CO3.XRD and SEM analyses are performed to obtain a well-structured LiFePO4 cathode material,and electrochemical performance tests shows that the first specific discharge capacity has reached 138.9 mAh/g at 0.1 C,which demonstates the repair and refabrication of spent cathode materials.