Pressure-Induced Dislocations and Their Influence on Ionic Transport in Li⁺-Conducting Argyrodites

Abstract

The influence of the microstructure on the ionic conductivity and cell performance is a topic of broad scientific interest in solid-state batteries. The current understanding is that interfacial decomposition reactions during cycling induce local strain at the interfaces between solid electrolytes and the anode/cathode, as well as within the electrode composites. Characterizing the effects of internal strain on ion transport is particularly important, given the significant local chemomechanical effects caused by volumetric changes of the active materials during cycling. Here, we show the effects of internal strain on the bulk ionic transport of the argyrodite Li₆PS₅Br. Internal strain is reproducibly induced by applying pressures with values up to 10 GPa. An internal permanent strain is observed in the material, indicating long-range strain fields typical for dislocations. With increasing dislocation densities, an increase in the lithium ionic conductivity can be observed that extends into improved ionic transport in solid-state battery electrode composites. This work shows the potential of strain engineering as an additional approach for tuning ion conductors without changing the composition of the material itself.