Effect Of Pressure On Performance Of Soft-packaged Lithium-ion Battery And Its Countermeasures

Power battery has been the focus and difficulty in the development of new energy vehicles.The performance of power battery pack mainly comes from two aspects:battery monomer and group technology of battery module.Excellent battery packs still have good electrical performance after lithium batteries are grouped.This research object is the ternary polymer lithium battery produced by an enterprise.Through the combination of theory and experiment,the paper studies the monomer of the battery from the angle of mechanics,and applies it to the design of the battery module in the project.The main works are as follows:First of all,structural characteristics,working principle and failure mechanism of lithium ion battery are studied.Review and analysis of the results in the first stage compression force cycle test carried out by the project team.From the three aspects of residual capacity,battery internal resistance and battery disassembly,the main direction of the influence of pressure on the performance of the power battery is defined.Secondly,based on the reference value of the first stage experiment,the optimization of the pressure is carried out.The pressure sensor is added in the experimental device,and the second stage pressure cycling test has been made.According to the multi angle analysis of residual capacity,release energy,coulombic efficiency,battery resistance,and battery disassembly,combined with the pressure changes recorded by the pressure sensor,the most suitable external pressure range is obtained.Thirdly,according to the structure of the common battery module and the structure of the experimental group in the previous stage,the experimental group with different pressure accommodation scheme is designed,and the third stage compression force cycling experiment is carried out.Through the summary and analysis of the experimental results,it is found that the elastic element can improve the performance of the battery.Finally,the design principles and key technologies of the module are studied.Then according to the needs of the project,combined with the results of the pressure cycle experiment,the battery module is designed and manufactured.Testing the samples by experiment and then complete the assembly of the power battery system.Research has shown that the addition of elastic components in modular design can extend the service life of the battery.The optimal pressure for soft package lithium-ion battery in the module design applied should be 69kPa.