By considering a range of materials simultaneously, these atomistic insights highlight a variety of important considerations that must be made when designing solid electrolyte materials. We propose that future studies should focus more on detailed investigations into the specific mechanisms that have been hinted at here, for example charge trapping or complex polyanionic motion at GBs and other important interfaces. Augmenting our fundamental understanding of these interfaces and their complex influence is crucial for the future development of solid electrolytes for solid-state batteries.