Modeling And Simulation Of Lithium Ion Diffusion Behavior Based On Mechanical-chemical Coupling

New energy storage devices represented by lithium batteries have achieved rapid development in recent years,but defects such as small capacity and short life of lithium batteries have become important reasons hindering the widespread development of lithium batteries.The capacity and l ife reduction of lithium-ion batteries are closely related to the stress generated in the electrodes during the charging and discharging process of the battery.During the charging and discharging of the battery,lithium ions will be inserted or precipitat ed from the battery electrodes,and the electrode is caused by the diffusion of lithium ions.Diffusion-induced stress and diffusion-induced stress damage the internal structure of the battery,resulting in a decrease in battery capacity and shortening of battery life.In order to reduce the diffusion-induced stress in the lithium-ion battery and make the lithium-ion battery have a longer cycle life,this paper has carried out a more systematic study on the diffusion-induced stress in the lithium battery el ectrode.In this paper,a mass transfer-stress two-way coupling model based on Bivolt number regulation is established to study the lithium ion concentration and diffusion-induced stress in the anode electrode of cylindrical lithium-ion battery during charging.Based on the finite difference method,the diffusion coupling equation of the mass transfer-stress bidirectional coupling under the control of the Bivolt number is solved,and the expression of the internal stress field of the electrode is obtained.The results show that by adjusting the electrochemical Pivot number during the charging process,the change trend of the diffusion-induced stress can be effectively controlled.Under the regulation of a small Bivolt number,the diffusion-induced stress in the electrode can be changed from a tensile stress state to a compressive stress state.To a certain extent,the fracture failure of the electrode caused by the tensile stress can be reduced,which is reasonable during the charging process.The adjusted Bivol number plays an important role in preventing battery failure and prolonging the service life of lithium-ion batteries.A mass transfer-stress bidirectional coupling model was established with the anode electrode of the lithium battery as the object t hrough COMSOL Multiphysics software,and the use of the Bivolt number to control the diffusion-induced stress in the lithium battery electrode was realized.The feasibility and correctness of the model are verified by the comparison between the calculation results and the simulation results.The simulation results show that the electrochemical Pivot number can control the entire electrochemical reaction process and regulate the diffusion-induced stress of lithium-ion battery electrodes caused by charging,a nd it plays an important role in the design of embeddable electrodes.