Abstract Evidences have accumulated that the cyclic diffusion-induced stress within lithiation-delithiation process will result in the cyclically evolutive mechanical damage of battery electrode, which adversely affects the mechanical integrity as well as the performance of the Li-ion battery. In this work, the mechanical degradation of electrode under electrochemical-mechanical condition is innovatively evaluated as a fatigue damage process, governed by the interaction between diffusion behaviour and stress generation, and accumulated fatigue damage affected stress–strain response. Structural configuration of a layered electrode plate is modeled in finite element software ABAQUS and a set of user subroutines are developed to implement the proposed fatigue evaluation approach for battery electrode. The constructed approach is proved to be able to simulate multifarious categories of fatigue damage accumulation trends of battery electrode. The strategy to correlate the electrochemistry represented damage with mechanical fatigue damage are proposed. Experimental performance tests are conducted to parameterize the fatigue damage model within the assessment approach for electrode material LiNi0.5Mn0.3Co0.2O2 (NMC532). After parameterization, further circulating charging-discharging experiments and fatigue damage simulations with respect to different C-rate conditions are carried out to study the applicability of the proposed evaluation model as well as the assumption between electrochemical and mechanical deterioration. It is observed that the electrode surface adhering to electrolyte is more prone to fracture in the cycling operation. The present research work shows that it is available to apply the fatigue damage method to study the gradually mechanical failure of battery electrode under electrochemical-mechanical condition.

中文翻译：

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锂离子电池电极循环机械损伤数值分析及实验验证

摘要 越来越多的证据表明，锂化-脱锂过程中的循环扩散诱导应力会导致电池电极的循环演化机械损伤，从而对锂离子电池的机械完整性和性能产生不利影响。在这项工作中，电极在电化学机械条件下的机械退化被创新地评估为疲劳损伤过程，受扩散行为和应力产生之间的相互作用控制，累积疲劳损伤影响应力-应变响应。在有限元软件 ABAQUS 中对分层电极板的结构配置进行建模，并开发了一组用户子程序来实现所提出的电池电极疲劳评估方法。证明所构建的方法能够模拟电池电极疲劳损伤累积趋势的多种类别。提出了将电化学表示的损伤与机械疲劳损伤相关联的策略。进行了实验性能测试，以参数化电极材料 LiNi0.5Mn0.3Co0.2O2 (NMC532) 评估方法内的疲劳损伤模型。参数化后，针对不同C-rate条件进行进一步循环充放电实验和疲劳损伤模拟，以研究所提出的评估模型的适用性以及电化学和机械劣化之间的假设。观察到粘附在电解质上的电极表面在循环操作中更容易断裂。