Study On The Influence Of Particle Size Distribution On The Structure And Electrochemical Stability Of Graphite-based Negative Electrode

The high-speed development of electronic products and new energy automobiles and other industries put forward higher requirements for lithium-ion batteries.High capacity electrode materials are the main means to improve the electrochemical performance of batteries at present,but it is difficult to realize commercial application of this kind of new batteries in a short time.The results show that the electrochemical performance of the battery can be improved to a certain extent by improving the mechanical stability of the electrodes without changing the main material of the existing electrodes.Particle size gradation is a method of proportionally matching powder materials with different particle sizes to improve the overall performance of mixtures.It is widely used in the field of concrete structure strengthening.In order to improve the overall performance of graphite-based anode materials,the method of particle size distribution was chosen in this paper.Firstly,the particle size distribution of graphite and graphite is selected to improve the mechanical properties of the electrode,electrical conductivity of the material and electrochemical performance of the material.Secondly,the particle size distribution of graphite and silicon is selected to improve the electrochemical performance of the graphite-based anode material by combining the characteristics of high strength and capacity of silicon particles.The main contents and conclusions of this paper are as follows:(1)Graphite/graphite anode materials were prepared by mixing 6 μm and 9 μm graphite with 18 μm graphite respectively.The effects of 5%,10% and 20% graphite mass fraction on the stability and electrochemical properties of the plates were studied.The results show that the tensile strength of the plate is 41.387 N before particle size gradation,45.2 N when the mass fraction of 6 μm graphite is 20%,343.3 mAh/g after 100 cycles,45.5 N when the mass fraction of 9 μm graphite is 5%,and 330.8 mAh/g after 100 cycles.After micro-tensile test and scratch test,SEM observation showed that the graphite anode material before particle size gradation had many defects,such as pore and crack on its surface.After adding small size graphite,the surface porosity was reduced,the anti-damage ability was enhanced,the cracks were reduced and the stability of the coating was higher after the coating was destroyed,which would be beneficial to lithium ion batteries.The electrochemical performance has a positive impact(2)Silicon/graphite anode materials were prepared by mixing 3,6 and 9 μm silicon particles with 18 μm graphite respectively.The effects of small silicon content of 5%,10% and 20% on the stability and electrochemical properties of the anode were studied.The results show that when the mass fraction of 3 μm silicon is 10%,the tensile strength of the plate can reach 46.6 N and the capacity can reach 393.4 mAh/g after 100 cycles;when the mass fraction of 6 μm silicon is 20%,the tensile strength of the plate can reach45.416 N and 472.4 mAh/g after 100 cycles;and when the mass fraction of 9 μm silicon is5%,the tensile strength of the plate can reach 46.073 N and the capacity after 100 cycles.It can reach 330.9 mAh/g.The tensile strength of the coatings increases obviously with the addition of small size silicon particle size gradation.After being destroyed,the cracks are reduced,the stability of the coatings is higher,and the battery capacity is also improved significantly.The stability of the coating and the electrochemical performance of the battery were improved by adding small size silicon particle size gradation.