Dynamics of the Garnet/Li Interface for Dendrite-Free Solid-State Batteries

Solid-state interfaces play a significant role in the overall electrochemical performance of solid-state batteries (SSBs). However, the understanding of interface dynamics between solid-state electrolytes (SSEs) and Li metal remains limited, especially their effects on Li dendrite growth. Herein, three different interfaces are fabricated based on garnet-type SSEs and the Li penetration behaviors across the interfaces are investigated. The lithiophilic garnet/Li interface, with an initially low resistance, can be gradually broken and the growing voltage hysteresis drives the Li nucleation and proliferation through the grain boundary of the garnet ceramic bulk. The results indicate that a three-dimensional garnet/Li interface can remain stable due to the decreased local current density and minimized Li volume change, thus suppressing the dendrite formation. This work not only provides further understanding of the relationship between the SSE/Li interface and Li dendrite growth but also provides guidelines for the future design of dendrite-free SSBs.