Testing And Modeling Of Mechanical Property Of Lithium Battery And Its Application In Safety Design Of Battery Pack

In the last few years,with the continuous improvement of battery technology,the proportion of electric vehicles in the automobile industry is increasing year by year.However,although electric vehicles have more advantages than traditional vehicles in terms of energy consumption and environmental protection,the battery packs of electric vehicles are easy to catch fire or even explode in the event of collisions,which endangers the personal safety of drivers.Therefore,the safety of power battery packs has attracted extensive attention.In order to improve the crashworthiness and driving safety of power battery packs,it is necessary to study the failure conditions of lithium batteries and power battery packs under collision,which are of great significance to improve the evaluation of collision safety of electric vehicles.This paper focuses on the mechanical response performance of power battery packs under impact conditions.The research contents mainly include testing and modeling of the mechanical properties of batteries and their performance evaluation,the multi-condition impact safety analysis of battery packs and the application of hierarchical structures in power battery packs.First of all,destructive experiments were carried out on the lithium battery under multi-conditions(including 8 extreme experimental conditions including flat extrusion,internal layer extrusion,frontal partial extrusion and lateral partial extrusion).During the experiments,the force-displacement curves and the battery voltage characteristics were recorded.The mechanical response characteristics of the batteries were analyzed to explore the impact of extrusion location and damage tolerance on the batteries.Then,the numerical model of lithium battery was established by means of membrane segmentation,and the chemical failure of internal short circuit of the battery was transformed into mechanical failure by taking membrane rupture as the sign of short circuit of the battery,and the results of numerical analysis are in good agreement with the experimental data,which verified the accuracy of the numerical model.Then,the whole battery pack model was established based on the battery model and the battery pack safety analysis was carried out according to relevant regulations.Finally,the square corner hierarchical structure(CHS)was designed by the corner hierarchical method to improve the battery pack protection structure.The purpose of this paper is to provide a reference for the design of the protective structure of battery packs,as well as the relevant safety analysis and detection,and to provide a new direction for the application of thin-walled structures.