Pressure effects on sulfide electrolytes for all solid-state batteries

All solid-state batteries are believed to be safer than their liquid counterparts owing to their use of nonflammable solid electrolytes. Nevertheless, unlike liquid electrolyte batteries, stack pressure is required during cycling to avoid contact losses between the electrodes and the solid electrolyte. Although recent studies have shown stack pressures to affect the capacity utilization of alloying anodes, an investigation of the effect of stack pressures on solid-state battery cyclability has not been performed so far. In this work, the effects of both initial fabrication pressure and operating stack pressure on the electrolyte's ionic conductivity and battery performance have been analyzed; the results show that initial fabrication pressure directly affects the porosity of the electrolyte and therefore the overall performance of the cell. Low operating stack pressure reduces the apparent ionic conductivity due to poor contact between the electrolyte and current collectors, but does not detrimentally affect the cyclability of solid-state batteries. These results can explain inconsistencies in the literature and provide a guideline toward standardized solid-state battery testing conditions and proper reporting benchmarks of the performance of solid-state batteries.