Battery decay and failure depend strongly on the solid electrolyte interphase (SEI), a surface corrosion layer that forms on the surface of all battery electrodes. Recently, we revealed the atomic structure of these reactive and sensitive battery materials and their SEIs using cryoelectron microscopy (cryo-EM). However, the SEI nanostructure's fundamental role and effect on battery performance remain unclear. Here, we use cryo-EM to discover the function of two distinct SEI nanostructures (i.e., mosaic and multilayer) and correlate their stark effects with Li metal battery performance. We identify fluctuations in crystalline grain distribution within the SEI as the critical feature differentiating the mosaic SEI from the multilayer SEI, resulting in their distinct electrochemical stripping mechanisms. Whereas localized Li dissolution occurs quickly through regions of high crystallinity in the mosaic SEI, uniform Li stripping is observed for the more ordered multilayer SEIs, which reduces Li loss during battery cycling by a factor of three. This dramatic performance enhancement from a subtle change in SEI nanostructure highlights the importance of cryo-EM studies in revealing crucial failure modes of high-energy batteries at the nanoscale.

电池的衰减和故障在很大程度上取决于固态电解质相（SEI），即在所有电池电极表面上形成的表面腐蚀层。最近，我们使用低温电子显微镜（cryo-EM）揭示了这些反应性和敏感电池材料及其SEI的原子结构。但是，SEI纳米结构的基本作用和对电池性能的影响尚不清楚。在这里，我们使用cryo-EM来发现两种不同的SEI纳米结构（即镶嵌和多层）的功能，并将它们的鲜明效果与锂金属电池的性能相关联。我们将SEI内晶粒分布的波动确定为区分镶嵌SEI与多层SEI的关键特征，从而导致了它们独特的电化学剥离机理。尽管通过镶嵌SEI中高结晶度区域会迅速发生局部Li溶解，但对于更有序的多层SEI则观察到均匀的Li剥离，这将电池循环期间的Li损失降低了三倍。SEI纳米结构的细微变化带来的显着性能提升，凸显了冷冻电镜研究在揭示纳米级高能电池的关键失效模式方面的重要性。