Solid-state batteries can suffer from catastrophic failure at high current densities due to solid electrolyte fracture, interface decomposition, or lithium filament growth. Failure is linked to chemomechanical material transformations that can manifest during electrochemical cycling. We systematically investigate how solid electrolyte microstructure and interfacial decomposition (e.g., interphase) affect failure mechanisms in lithium thiophosphates (Li₃PS₄, LPS) electrolytes. Kinetically metastable interphases are engineered with iodine doping, and microstructural control is achieved using milling and annealing processing techniques. In situ transmission electron microscopy reveals iodine diffusion to the interphase, and upon electrochemical cycling, pores are formed in the interphase region. In situ synchrotron tomography reveals that interphase pore formation drives edge fracture events, which are the origin of through-plane fracture failure. Fractures in thiophosphate electrolytes actively grow toward regions of higher porosity and are affected by heterogeneity in microstructure (e.g., porosity factor). This work provides fundamental design guidelines for high-performance solid-state batteries.

由于固态电解质破裂，界面分解或锂灯丝生长，固态电池在高电流密度下可能会遭受灾难性故障。失效与电化学循环过程中可能出现的化学机械材料转变有关。我们系统地研究了固体电解质的微观结构和界面分解（例如，相间）如何影响硫代磷酸锂（Li ₃ PS ₄，LPS）电解质的失效机理。动力学上稳定的中间相用碘掺杂进行了工程设计，并通过铣削和退火处理技术实现了微结构控制。原位透射电子显微镜显示碘扩散到相间，并且在电化学循环中，在相间区域中形成孔。原位同步加速器层析成像显示，相间孔形成驱动边缘断裂事件，这是贯穿平面断裂失败的根源。硫代磷酸盐电解质中的裂纹会朝着较高孔隙度的区域活跃生长，并受到微观结构异质性（例如孔隙度因子）的影响。这项工作为高性能固态电池提供了基本的设计准则。