  Solid electrolytes for solid-state Li-ion batteries are stimulating
considerable interest for next-generation energy storage applications. The
Li$_7$La$_3$Zr$_2$O$_{12}$ garnet-type solid electrolyte has received
appreciable attention as a result of its high ionic conductivity. However,
several challenges for the successful application of solid-state devices based
on Li$_7$La$_3$Zr$_2$O$_{12}$ remain, such as dendrite formation and
maintaining physical contact at interfaces over many Li
intercalation/extraction cycles. Here, we apply first-principles density
functional theory to provide insights into the Li$_7$La$_3$Zr$_2$O$_{12}$
particle morphology under various physical and chemical conditions. Our
findings indicate Li segregation at the surfaces, suggesting Li-rich grain
boundaries at typical synthesis and sintering conditions. On the basis of our
results, we propose practical strategies to curb Li segregation at the
Li$_7$La$_3$Zr$_2$O$_{12}$ interfaces. This approach can be extended to other
Li-ion conductors for the design of practical energy storage devices.

Materials Science