Effects of sublattice symmetry and frustration on ionic transport in garnet solid electrolytes

TL;DR

This study combines group theory and molecular dynamics to explore how structural symmetry and frustration influence ionic conductivity in garnet solid electrolytes, revealing that disorder enhances transport efficiency.

Contribution

The paper introduces a combined group-theoretic and molecular dynamics approach to link structural phases and ionic transport in garnet electrolytes, identifying new phases and the role of frustration.

Findings

Ordered phases correlate with low conductivity regions.

Disorder enhances ionic transport in garnet electrolytes.

Incommensurability-induced frustration affects Li mobility.

Abstract

We use rigorous group-theoretic techniques and molecular dynamics to investigate the connection between structural symmetry and ionic conductivity in the garnet family of solid Li-ion electrolytes. We identify new ordered phases and order-disorder phase transitions that are relevant for conductivity optimization. Ionic transport in this materials family is controlled by the frustration of the Li sublattice caused by incommensurability with the host structure at non-integer Li concentrations, while ordered phases explain regions of sharply lower conductivity. Disorder is therefore predicted to be optimal for ionic transport in this and other conductor families with strong Li interaction.