基于有限离散元的硅薄膜电极断裂行为研究  

Research on the fracture behavior of silicon thin-film electrodes based on FDEM

作　　者：田甜 张锴[1] 张育维 郑百林[1] TIAN Tian;ZHANG Kai;ZHANG YuWei;ZHENG BaiLin(School of Aerospace Engineering and Applied Mechanics,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学航空航天与力学学院,上海200092

出　　处：《中国科学:技术科学》2025年第4期753-764,共12页Scientia Sinica(Technologica)

基　　金：国家自然科学基金(批准号:12372173);上海市自然科学基金(编号:23ZR1468600)资助项目。

摘　　要：由于硅的材料特性,锂离子电池中的硅薄膜电极在嵌锂和脱锂过程中会经历显著的体积膨胀,导致电极内部出现裂纹扩展、闭合以及层间脱黏现象.本文使用有限离散元法(FDEM)建立硅薄膜的力-电化学模型,基于显式数值积分方法模拟锂离子电池中硅负极薄膜在复杂应力环境下的断裂行为,同时研究锂离子在嵌入与脱嵌过程中引起的浓度动态变化.该模型深入模拟了锂离子电池在恒流充放电循环过程中硅薄膜的裂纹产生与扩展机制,并指出电极与基底之间的脱层行为最早在脱锂阶段与裂纹的扩展过程同步发生.在此基础上,本文进一步探讨了硅薄膜表面粗糙度作为影响电极裂纹成核的关键因素,通过对比不同粗糙度的硅薄膜在恒流充放电条件下的模拟结果,发现表面粗糙度显著影响了起裂时间、累计裂纹长度和最大张开度等关键参数.本文为更深入地理解硅负极薄膜在循环过程中的失效机制、优化电池设计和提升电池性能提供有力的理论支持.The significant expansion of silicon thin-film electrodes during lithiation and delithiation due to the inherent properties of silicon leads to crack propagation,closure,and interlayer delamination.This study employs the finite-discrete element method(FDEM)to develop a coupled mechanical-electrochemical model for silicon thin films.We construct the model with explicit numerical integration to simulate the fracture behavior of silicon anode thin films under complex stress conditions while monitoring dynamic concentration changes caused by lithium-ion insertion and extraction.The model provides an in-depth simulation of the crack initiation and propagation mechanisms in silicon thin films during constant-current charge-discharge cycles.Our findings indicate that delamination between the electrode and substrate occurs synchronously with crack propagation,beginning as early as the delithiation stage.Additionally,we explore the influence of silicon thin-film surface roughness on electrode crack nucleation.Comparative simulations of silicon thin films with varying surface roughness values under constant-current charging and discharging conditions reveal that surface roughness significantly impacts critical parameters such as the time of crack initiation,cumulative crack length,and maximum crack opening displacement.This study offers strong theoretical support for understanding the failure mechanisms of silicon anode thin films during cycling,aiming to optimize battery design and enhance performance.

关 键 词：锂离子电池 力-电化学耦合 硅薄膜 有限离散元法 断裂 

分 类 号：TM912[电气工程—电力电子与电力传动]