How Soft Lithium Cracks Hard Ceramic

A Max Planck Institute for Sustainable Materials team has resolved a central puzzle in solid-state batteries: how lithium, a soft metal, can penetrate a stiff ceramic electrolyte. Working under vacuum and at cryogenic temperatures, the researchers preserved the reactive interfaces while examining dendrite paths at microscopic scale. Their Nature paper supports a mechanically driven explanation: stress concentrated by a growing lithium filament opens and advances cracks through the garnet electrolyte. That evidence helps separate fracture from a competing theory centered on electron leakage and remote lithium nucleation. It is not a commercial battery breakthrough by itself, but it gives engineers a clearer failure mechanism to design against.