Solid-state electrolytes (SSEs) have attracted substantial attention for next-generation Li-metal batteries, but Li-filament propagation at high current densities remains a significant challenge. This study probes the coupled electrochemical-morphological-mechanical evolution of Li-metal-Li₇La₃Zr₂O₁₂ interfaces. Quantitative analysis of synchronized electrochemistry with operando video microscopy reveals new insights into the nature of Li propagation in SSEs. Several different filament morphologies are identified, demonstrating that a singular mechanism is insufficient to describe the complexity of Li propagation pathways. The dynamic evolution of the structures is characterized, which demonstrates the relationships between current density and propagation velocity, as well as reversibility of plated Li before short-circuit occurs. Under deep discharge, void formation and dewetting are directly observed, which are directly related to evolving overpotentials during stripping. Finally, similar Li penetration behavior is observed in glassy Li₃PS₄, demonstrating the relevance of the new insights to SSEs more generally.

固态电解质（SSE）已引起下一代锂金属电池的广泛关注，但是锂丝在高电流密度下的扩散仍然是一个重大挑战。本研究探讨了Li-metal-Li ₇ La ₃ Zr ₂ O ₁₂界面的电化学-形态-力学耦合演化。同步电化学与操作的定量分析视频显微镜揭示了对SSE中Li传播性质的新见解。确定了几种不同的灯丝形态，表明单一机制不足以描述Li传播途径的复杂性。表征了结构的动态演化，这表明了电流密度与传播速度之间的关系，以及在发生短路之前镀Li的可逆性。在深层放电下，直接观察到空隙的形成和去湿，这与汽提过程中形成的超电势直接相关。最后，在玻璃状的Li ₃ PS _4中观察到了相似的Li渗透行为，这更普遍地表明了新见解与SSE的相关性。