High-Precision Quantifications of Dendrite Initiation Dynamics in Garnet Solid Electrolytes

Solid-state electrolytes have the potential to stabilize lithium metal anodes, which hold the promise to increase the energy density of lithium-ion batteries. However, lithium metal dendrites that occur locally at the solid-solid interface plague the solid-state lithium metal cells during charging, rendering high safety risks in practical applications. While multiple explanations have been proposed, understandings of the dynamics preceding and causing the metal penetration in solid electrolytes are still not conclusive. Here, by testing hundreds of highly consistent LLZTO samples and utilizing a novel operando technique on conventional cell geometry, we observed consistent and statistically significant phenomena. The characteristic time to dendrite initiation was measured and coincided with the Sand's time scaling traditionally reserved for liquid electrolytes, indicating similar transport limitations in garnet solid electrolytes. Deviations in scaling and additional normalization were also explored. This new fundamental understanding not only explains the electrochemical origin of dendritic initiation but also provides future insight into optimal all-solid-state battery design.