Abstract The fracture phenomenon of high-capacity electrode materials during electrochemical cycles poses a major limitation on further advancements in Li-ion batteries. In this paper, a diffusion-creep-stress-fracture coupling model using the phase-field method is established to explore the chemo-mechanical relaxation effect on the fracture tolerance in a tin-based cylindrical electrode during lithiation. The results show that the creep relaxation mechanisms have twofold influence on the evolution of the multi-field system by altering the distribution of stresses. On the one hand, the relaxation mechanism which is crack size-dependent can improve the mechanical stability and fracture resistance of a tin-based electrode; on the other hand, the Li distributions accounting for creep are more uneven than those without creep, which may result in a reduction in usable capacity. Furthermore, the critical state of charge and its improvement for safe state due to creep relaxation are found to be size-dependent with regard to crack size. It can be associated to the stress concentration effect of flaws which can result in the earlier crack propagation and insufficient creep accumulation for a sharper (or longer) crack with large stress concentration.

中文翻译：

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化学机械弛豫效应对锡基电极断裂容限的相场建模

摘要 电化学循环过程中高容量电极材料的断裂现象严重限制了锂离子电池的进一步发展。在本文中，使用相场法建立了扩散-蠕变-应力-断裂耦合模型，以探索化学-机械弛豫对锂化过程中锡基圆柱电极断裂容限的影响。结果表明，蠕变松弛机制通过改变应力分布对多场系统的演变具有双重影响。一方面，依赖于裂纹尺寸的松弛机制可以提高锡基电极的机械稳定性和抗断裂性；另一方面，考虑蠕变的锂分布比没有蠕变的更不均匀，这可能会导致可用容量减少。此外，发现临界电荷状态及其由于蠕变松弛导致的安全状态改善与裂纹尺寸有关。它可能与裂纹的应力集中效应有关，裂纹会导致裂纹较早扩展，并且对于具有较大应力集中的较尖锐（或较长）裂纹而言，蠕变累积不足。