All-solid-state batteries (ASSBs) are currently discussed to increase the energy and/or power density, and are expected to be one of the next generation lithium-based battery technologies. However, the cell concept does not come without problems, as volume changes occurring for the active electrode material can lead to significant capacity fading on extended cycling. This mainly originates from a loss of contact of the active material to the carbon additive and the solid electrolyte. Various research attempts were made to limit capacity fading, among them, the advantageous effect of pressure on the performance of ASSBs has been demonstrated several times , and could be assigned to decreased contact resistance and reduction of volume change-induced contact loss between particles during cycling. In addition, the application of pressure can have an impact on the ionic conductivity of solid electrolytes since compression results in a lowering of the accessible volume for ions. A representative example for the effect on crystal structure on the pressure dependence of ionic conductivity is (Li, Na, K)-β-Al2O3. While the conductivity of Li-β-Al2O3 has a positive correlation with pressure, the mobility of larger Na + -ions in β-Al2O3 is mostly indifferent to pressure changes. On the contrary, increasing the ionic radius as in K-β-Al2O3 results in a negative correlation with pressure. As one alternative to lithium-ion batteries, all-solid-state fluoride ion batteries (ASS-FIBs) have been investigated over the last years with increasing number of reports in the last decade. These systems are not only of interest due to their high theoretical capacities (5000 Wh L -1 ), but also due to a wide potential window provided by fluoride conductors. However, the required high operating temperature and capacity fading upon cycling are some of the main challenges in harvesting the full potential of ASSFIBs. Apart from few solid fluoride conductors (BaSnF4 , PbSnF4 , CsPb0.9K0.1F2.9 ) which show room temperature fluoride-ion conductivity at range of 10 -3 -10 -4 S cm -1 at the cost of a reduced electrochemical stability, solid electrolytes with high electrochemical stability such as La0.9Ba0.1F2.9 and Ba0.6La0.4F2.6 used in rechargeable FIBs still require high operating temperatures of ~ 150 -170 °C. Up to this point, only little is known on the pressure dependence of conductivity for fluoride ion conductors. One study reports the pressure dependence of the ionic conductivity of cubic and orthorhombic PbF2 in detail , which is frequently used as a reference electrode for FIBs.