All-solid-state batteries (ASSBs) represent a significant leap forward compared to conventional liquid-electrolyte based batteries, offering enhanced energy density, improved safety, extended cycle longevity, and reduced environmental footprint. However, the persistent challenge of uncontrollable dendrite growth within solid electrolytes (SEs) has posed substantial obstacles to the realization of Li metal ASSBs. This study develops a phase field model to unveil a dynamic interplay between Li dendrite growth and crack propagation in the polycrystalline Li7La3Zr2O12 (LLZO) solid electrolyte. Our modeling highlights distinct nucleation sites for Li electrodeposition, localized in proximity to the electrode/SE interface, a phenomenon sensitive to cell geometry. Li deposition initiates local stress accumulation that wedges the SE to cracking, and fracture induced stress relaxation facilitates further Li electrodeposition. Remarkably, a reciprocal relationship emerges between Li dendrite growth and crack propagation, each process reinforcing the other in an alternating manner. The dynamic interplay unveils a characteristic “wait-and-go” temporal sequence, where the progression of Li dendrites consistently trails behind the crack tip, aligning with the previous experimental observations. Drawing from the reciprocal dynamics, we identify practical stress-engineering strategies to mitigate catastrophic cell failure by simultaneously retarding Li dendrite growth and redirecting the crack propagation paths. Our findings offer electrochemo-mechanical insights in cell design and stress management, thereby opening a unique pathway towards the realization of safe and durable Li metal ASSBs.

中文翻译：

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锂金属固态电池中枝晶生长和开裂的动态相互作用

与传统的基于液体电解质的电池相比，全固态电池 （ASSB） 代表了重大飞跃，可提供更高的能量密度、更高的安全性、更长的使用寿命并减少对环境的影响。然而，固体电解质 （SEs） 中树枝状生长不受控制的持续挑战对锂金属 ASSB 的实现构成了重大障碍。本研究开发了一个相场模型，以揭示多晶 Li7La3Zr2O12 （LLZO） 固体电解质中锂枝晶生长和裂纹扩展之间的动态相互作用。我们的建模突出显示了 Li 电沉积的不同成核位点，这些位点位于电极/SE 界面附近，这是一种对电池几何形状敏感的现象。锂沉积引发局部应力积累，使 SE 楔入开裂，而断裂诱导的应力松弛促进了进一步的锂电沉积。值得注意的是，锂枝晶生长和裂纹扩展之间存在互惠关系，每个过程都以交替的方式加强另一个过程。动态相互作用揭示了一个典型的“等待和走”时间序列，其中 Li 枝晶的进展始终落后于裂纹尖端，与之前的实验观察结果一致。从互惠动力学中，我们确定了实用的应力工程策略，通过同时延缓 Li 枝晶生长和重定向裂纹扩展路径来减轻灾难性的细胞失效。我们的研究结果为电池设计和应力管理提供了电化学力学见解，从而为实现安全耐用的锂金属 ASSB 开辟了一条独特的途径。