Effect of Uniaxial Stack Pressure on the Performance of Nanocrystalline Electrolytes and Electrode Composites for All-Solid-State Fluoride-Ion-Batteries

If all solid-state fluoride ion batteries want to compete with existing battery technologies, significant improvements in terms of cyclic stability are necessary to fully access the high specific capacities this battery concept can provide in theory. In this study, we report the development of a high-pressure, high-temperature battery operation stand for battery cycling under inert conditions inside a glovebox. This stand was then used to investigate the effect of stack pressure on the cell performance of conversion-based as well as intercalation-based electrode materials for fluoride ion batteries. It was found that cyclic stability as well as energy efficiency is strongly increased compared to non-pressure conditions, which is assigned to sustained inter-particle contact. Thus, the cell-design must be considered carefully to be able to distinguish intrinsic material properties from percolation- and interphase-related impacts on the cell behavior. Further, the effect of pressure on the ionic conductivity of common solid fluoride ion conductors is investigated.