Suppressing dendrites via lateral lithium flux in Li metal solid-state batteries

Lithium dendrite growth at the lithium-solid-state electrolyte (SSE) interface, driven by void formation, remains a major barrier to the deployment of Li metal solid-state batteries. Here, we reveal a mechanism of lateral lithium flux that explains how interfacial layers (ILs) along the Li/SSE interface enable suppression of void formation, thereby preventing dendrite growth. Using Li₃Sb as a model IL and Li₇La₃Zr₂O₁₂ as a benchmark SSE, we directly visualize and quantify lateral lithium transport, demonstrating that ILs mitigate void formation by defocusing the local current density. This mechanism accounts for the cycling stability of IL-functionalized Li/SSE interfaces and provides design principles for safe, high-energy-density Li metal solid-state batteries.