Study On Separation Process Of Cathode And Anode Mixed Materials From Spent Lithium-ion Battery

With the rapid upgrading of science and technology,the continuous improvement of people's living standards,and the increasingly stringent environmental protection policies,the application fields of lithium-ion batteries in life are becoming more and more extensive,and the frequency of use is getting higher and higher.The output of lithium-ion batteries is also increasing.getting bigger.However,lithium-ion batteries have a certain useful life.As the output of lithium-ion batteries increases,the number of spent lithium-ion batteries will also increase.Spent lithium-ion batteries contain a lot of valuable metals and harmful substances.Improper disposal will cause serious damage to the ecological environment and human health.Therefore,it is of great significance to recycle and recycle the spent lithium-ion batteries.In recent years,with the efforts of many scientific research teams,great progress has been made in the recycling of spent lithium-ion batteries,and many research results have been harvested.However,cathode and anode effects have been achieved in the recycling of spent lithium-ion batteries.There are still shortcomings in the efficient and high-purity separation of polar materials.In this thesis,the cathode and anode electrode mixture materials?commonly known as black powder?obtained by the crusher for crushing the spent lithium ion battery provided by the company are taken as the research object.The mechanism that the positive electrode material and the anode electrode material cannot be directly separated by flotation is studied.Oxygen roasting modification mechanism,optimization of aerobic roasting process flow,and through orthogonal experimental analysis,optimized experimental conditions for the separation of cathode and anode electrode materials using flotation technology were optimized.The findings are as follows:1.It is difficult for flotation separation of the cathode and anode electrode mixed materials of spent lithium-ion batteries.By powder X-ray diffractometer and inductively coupled plasma emission spectrometer,it was determined that the main phases in the cathode and anode electrode mixed materials of spent lithium ion batteries are LiNi_0.8Co_0.1Mn_0.1O₂,LiCoO₂ and C,of which the content of the cathode electrode material is 59.99%The content of anode material is 36.98%.X-ray photoelectron spectroscopy was used to analyze the characteristic elements of the PVDF adhesive,and it was determined that the F element has a functional group structure on the surface of the electrode particles.Combined with the distribution state of the F element,an organic film was attached to the surface of the electrode particles.By scanning electron microscopy,it was confirmed that a binder still exists between the electrode particles.It is because of the presence of the binder that the surface difference between the cathode electrode material and the anode electrode material is reduced,which is the main reason why the conventional f lotation of graphite materials in black powder materials is difficult to effectively separate.2.Study on the aerobic modification mechanism,optimal conditions and process flow of cathode and anode electrode mixed materials for spent lithium ion batteries.Orthogonal test for aerobic roasting of cathode and anode electrode mixed materials of spent lithium ion batteries,the optimum aerobic roasting conditions were determined as follows:roasting temperature 550°C,roasting time 30 min,and heating rate 10°C/min Under the optimal firing conditions,the PVDF removal rate of the electrode material was 97.82%,and the carbon retention rate was 91.06%.By optimizing the aerobic roasting process of the electrode material,the best process w as determined as follows:aerobic roasting and then sieving and separation.The powdered X-ray diffractometer,inductively coupled plasma emission spectrometer,X-ray photoelectron spectroscopy,and scanning electron microscope were used to analyze the electrode materials after aerobic roasting,and the phase and The crystal structure does not change,and the organic film coated on the surface of the electrode particles is decomposed and oxidized by aerobic baking at high temperature.3.Flotation separation of cathode and anode electrode mixed materials for spent lithium ion batteries.Through orthogonal experiments on the flotation separation of cathode and anode electrode mixed materials of spent lithium ion batteries,the optimal flotation separation conditions were determined as follows:slurry concentration 8%,stirring speed 1600 r/min,drug dose 50 g/t,With a pH value of 1.0and aeration volume of 0.1 m³/h,flotation separation experiments were performed under this optimal technical scheme.The recovery rate of the cathode electrode material was 92.50%,and the concentrate grade was 97.79%.