The solid-solid contact interface is crucial for the reliability of solid-state energy storage systems. The contact condition becomes more complicated when lithium (Li) metal is used as the anode. The contact between solid electrolyte (SE) and Li metal is inferior compared to the liquid/solid interface in conventional Li-ion batteries. Experimental evidence has shown that improper operating conditions of solid-state batteries can lead to electro-chemo-mechanical failures at the Li/SE interface, including the formation of voids and the penetration of Li. In this study, a unified phase-field model is developed to investigate these two mechanisms. The model considers the coupled electro-chemo-mechanical processes including void diffusion, lattice annihilation, stripping and plating reactions, and plastic deformation of Li metal. The study begins with a revisit of the deformation-mechanism map for Li metal under a wide range of temperatures, stress, and deformation rates. This map serves as the basis for the mechanical characterization in the phase-field model. The large inelastic deformation of Li is considered by introducing an advection term into the Allen-Cahn equation, which is used to describe the dynamic evolution of the Li and void phases. The effects of current density and stack pressure on void evolution and Li penetration are studied based on the model predictions. By combining the simulation results with the experimental data from publications, we obtain the stable operation zone of stack pressure and applied current density. In this zone, the Li/SE interface can enable stable stripping and plating of Li metal. The same phase-field modeling framework is transferred to investigate the Li-Mg alloy/SE interface considering Li-Mg alloy is also used as the anode. The fundamental difference between Li/SE and Li-Mg/SE is analyzed accordingly. This study provides a useful tool for the design, manufacturing, and management of next-generation batteries by providing important scientific insights into the electro-chemo-mechanical processes of different anode materials under various operational conditions.

中文翻译：

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模拟锂-固体电解质界面处的电化学-机械故障：空洞演化和锂渗透


固-固接触界面对于固态储能系统的可靠性至关重要。当使用锂（Li）金属作为阳极时，接触条件变得更加复杂。与传统锂离子电池中的液/固界面相比，固体电解质（SE）和锂金属之间的接触较差。实验证据表明，固态电池的不当操作条件可能会导致Li/SE界面出现电化学机械故障，包括空隙的形成和Li的渗透。在本研究中，开发了一个统一的相场模型来研究这两种机制。该模型考虑了电化学机械耦合过程，包括空隙扩散、晶格湮灭、剥离和电镀反应以及锂金属的塑性变形。该研究首先重新审视锂金属在各种温度、应力和变形率下的变形机制图。该图作为相场模型中机械表征的基础。通过在 Allen-Cahn 方程中引入平流项来考虑 Li 的大非弹性变形，该方程用于描述 Li 相和空相的动态演化。基于模型预测，研究了电流密度和电堆压力对孔隙演化和锂渗透的影响。通过将模拟结果与出版物中的实验数据相结合，我们获得了电堆压力和施加电流密度的稳定运行区域。在此区域中，Li/SE界面可以实现Li金属的稳定剥离和电镀。考虑到 Li-Mg 合金也用作阳极，相同的相场建模框架被转移到研究 Li-Mg 合金/SE 界面。 据此分析了Li/SE与Li-Mg/SE的根本区别。这项研究为下一代电池的设计、制造和管理提供了有用的工具，为不同阳极材料在各种操作条件下的电化学机械过程提供了重要的科学见解。