Simulation study on the impact of graphite anode particles on lithium-ion battery capacity fading and SEI film growth
Lithium-ion batteries using graphite as the negative electrode material are widely used in the field of new energy,but their capacity attenuation after long-term charge and discharge cycles will significantly shorten the service life of the battery.One of the primary factors influencing battery cycle life is the growth of the solid electrolyte interface(SEI)layer on the anode surface.This growth is influenced by the electrolyte composition,preparation process,and the structure of the graphite material.In this study,we develop a model to describe battery capacity decay based on the growth reaction of the SEI film and investigate the impact of graphite structure on capacity decay and SEI film growth through simulations.The results show that the larger the particle size of the anode material is,the faster the SEI film thickness increases and the battery life is significantly reduced.Throughout the charge/discharge cycles,the initial cycle experiences the most rapid capacity decay,then the aging rate slows down and stabilizes as the SEI film thickness increases in subsequent stage.The reduction in the diffusion coefficient of the solvent in the SEI film and the porosity of the SEI layer will slow down the battery capacity fading rate.Notably,the inward diffusion of solvent through the SEI film to the anode surface is believed to be the rate-determining step in the continuous growth of the SEI film.These findings provide fundamental insights and guidance for optimizing the preparation of anode coatings.
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