Particle Morphology and Lithium Segregation to Surfaces of the Li$_7$La$_3$Zr$_2$O$_{12}$ Solid Electrolyte

TL;DR

This study uses first-principles calculations to analyze particle surface morphology and lithium segregation in Li7La3Zr2O12 solid electrolytes, offering insights to improve interface stability in solid-state batteries.

Contribution

It provides the first detailed theoretical analysis of lithium segregation and particle morphology in Li7La3Zr2O12, suggesting strategies to mitigate interface issues.

Findings

Li segregates at particle surfaces under typical synthesis conditions

Li-rich grain boundaries are likely to form

Strategies proposed to reduce lithium segregation at interfaces

Abstract

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.