We present a mechanistic theory for predicting void evolution in the Li metal electrode during the charge and discharge of all-solid-state battery cells. A phase field formulation is developed to model vacancy annihilation and nucleation, and to enable the tracking of the void-Li metal interface. This is coupled with a viscoplastic description of Li deformation, to capture creep effects, and a mass transfer formulation accounting for substitutional (bulk and surface) Li diffusion and current-driven flux. Moreover, we incorporate the interaction between the electrode and the solid electrolyte, resolving the coupled electro-chemical-mechanical problem in both domains. This enables predicting the electrolyte current distribution and thus the emergence of local current 'hot spots', which act as precursors for dendrite formation and cell death. The theoretical framework is numerically implemented, and single and multiple void case studies are carried out to predict the evolution of voids and current hot spots as a function of the applied pressure, material properties and charge (magnitude and cycle history). For both plating and stripping, insight is gained into the interplay between bulk diffusion, Li dissolution and deposition, creep, and the nucleation and annihilation of vacancies. The model is shown to capture the main experimental observations, including not only key features of electrolyte current and void morphology but also the sensitivity to the applied current, the role of pressure in increasing the electrode-electrolyte contact area, and the dominance of creep over vacancy diffusion.
翻译:我们提出了一个机械理论,用于预测所有固体电池电池充电和排放期间李金属电极的无效演进; 开发了一个分阶段的实地配制,以模拟空置销毁和核核粒化,从而能够跟踪白-利金属界面。 同时,我们提出了一个关于李变形的粘塑性描述,以捕捉爬变异效应,以及用于替代(桶和表面)李扩散和当前驱动通量的大规模传输配方计算; 此外,我们纳入了电极和固态电解密之间的相互作用,解决了两个域的电化学-机械问题并存。这可以预测电解当前电解分布,从而能够发现当地“热点”的“热点”的出现,这些“热点”是形成和细胞死亡的先导因素。 理论框架是数字化的,并且进行了单一和多空的案例研究,以预测真空和当前热点的演变,作为应用压力、物质特性和电荷的函数(放大和循环历史)的函数,解决了电解和电化学-化学-机械化-机械化-机械化两个领域的问题。 在散变现的变异化、 解和主要变现变现变变和变变变变的变的模型中, 显示的磁和变现的变现和变压的变异化和变现的变异化和变现的变的变的变现变现变的变的变现的变的变的变的变和变的变的变和变的变的变和变的变的变的变和变的变的变和变的变现的变的变的变的变的变现变的变的变和变的变的变的变的变的变,只是到的变到和变到的变到的变到的变到和变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到的变到