Mechanical behavior analysis of high power commercial lithium-ion batteries  

作　　者：Ruicheng Shen Shaojun Niu Guobin Zhu Kai Wu Honghe Zheng 

机构地区：[1]College of Energy,Soochow University,Suzhou 215006,China [2]Contemporary Amperex Technology Limited,Ningde 352100,China

出　　处：《Chinese Journal of Chemical Engineering》2023年第6期315-322,共8页中国化学工程学报（英文版）

基　　金：financially supported by the National Key Research&Development Program of China(2016YFB0100400);the National Natural Science Foundation of China(21875154 and 22179090)。

摘　　要：In application,lithium-ion cells undergo expansion during cycling.The mechanical behavior and the impact of external stress on lithium-ion battery are important in vehicle application.In this work,18 Ah high power commercial cell with Li Ni_(0.5)Co_(0.2)Mn_(0.3)O_(2)/graphite electrode were adopted.A commercial compress machine was applied to monitor the mechanical characteristics under different stage of charge(SOC),lifetime and initial external force.The dynamic and steady force was obtained and the results show that the dynamic force increases as the SOC increasing,obviously.During the lifetime with high power driving mode,different external force is shown to have a great impact on the long-term cell performance,with higher stresses result in higher capacity decay rates and faster impedance increases.A proper initial external force(900 N)provides lower impedance increasing.Postmortem analysis of the cells with2000 N initial force suggests a close correlation between electrochemistry and mechanics in which higher initial force leads to higher direct current internal resistance(DCIR)increase rate.In addition,for the cell with higher external force,deformation of the cathode and thicker solid electrolyte interface(SEI)film on the surface of anode and separator are observed.Porosity reduction and closure was also verified after cycles which is an obstacle to the lithium ion transferring.The largest cause of the observed capacity decline was the loss of active lithium through autopsy analysis.In addition,for the cell with higher external force,deformation of the cathode and thicker SEI film on the surface of anode and separator are observed.Porosity reduction and closure was also verified after cycles which is an obstacle to the lithium ion transferring.The largest cause of the observed capacity decline was the loss of active lithium through autopsy analysis.

关 键 词：Lithium-ion batteries External mechanical pressure Capacity fade Static pressure Dynamic pressure 

分 类 号：TM912[电气工程—电力电子与电力传动]