Dendrite growth and crack propagation are two major hurdles on the road towards the large-scale commercialization of lithium metal all-solid-state batteries (ASSBs). Due to the high multiphysics coupled nature of the underlying dendrite growth mechanism, understanding it has been difficult. Herein, for the first time, an electrochemical-mechanical model is established that directly couples dendrite growth and crack propagation from a physics-based perspective at the cell level. Results reveal that overpotential-driven stress propels a crack to penetrate through the solid electrolyte, creating vacancies for dendrite growth, leading to the short circuit of the battery. Thus, high lithiation/charging rate and low conductivity of electrolytes can accelerate the electrochemical failure of the battery. It is further discovered that Young's modulus E_LLZO of the electrolyte has competing contributions to the fracture and dendrite growth; specifically, when E_LLZO = 40–100 GPa, the short circuit is triggered early. A larger toughness value hinders the crack propagation and mitigates the Li dendrite growth. The developed multiphysics model provides an in-depth understanding of the coupling of crack propagation and dendrite growth within ASSBs and an insightful mechanistic design guidance map for robust and safe ASSB cells.

中文翻译：

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解锁全固态电池中枝晶生长和裂纹扩展的电化学-机械耦合行为

枝晶生长和裂纹扩展是锂金属全固态电池（ASSB）大规模商业化道路上的两大障碍。由于潜在的枝晶生长机制的高度多物理场耦合特性，理解它一直很困难。在此，首次建立了电化学机械模型，该模型从基于物理的角度在电池水平上直接耦合枝晶生长和裂纹扩展。结果表明，过电位驱动的应力推动裂纹穿透固体电解质，为枝晶生长创造空位，导致电池短路。因此，电解质的高锂化/充电速率和低电导率会加速电池的电化学失效。进一步发现杨氏模量电解质的E _LLZO对断裂和枝晶生长具有竞争性贡献；具体而言，当E _LLZO = 40-100 GPa 时，短路会提前触发。较大的韧性值会阻碍裂纹扩展并减缓锂枝晶的生长。开发的多物理场模型提供了对 ASSB 内裂纹扩展和枝晶生长耦合的深入理解，并为稳健和安全的 ASSB 电池提供了有见地的机械设计指导图。