Meso-scale mechanical characterization of polymeric, oxidic and sulfidic solid-state electrolytes until failure

The mechanical cell safety is one of the three safety pillars together with electrical and thermal safety 1, 2. Due to an integrity loss of the separator, an internal short circuit could appear and in the worst case lead to a selfamplifying thermal runaway 3-5. To avoid such failure processes due to mechanical loads the properties of the cell components need to be well known. In this work five solid-state electrolytes are investigated. A PEO/PO with LiTFSI and a sulfidic argyrodite are studied by tensile and compression testing whereas three different oxides LICGC, LAGP and LATP are tested under 4-point-bending and compression loads. This study highlights that there are not only significant differences among the different solid-state electrolyte classes, but also within a class itself. In the compression test, e.g., the average strains for the different materials are 88.9 % for the PEO/PO, 5.1 % for the LICGC, 4.9 % for the LAGP, 8.7 % for the LATP and 50.3 % for the argyrodite. Besides the compression strain values, also the Young's, tangent, compression and bending moduli, the failure strengths and the maximum elongations are determined. The acquired results are giving detailed understanding of the mechanical behavior and load limits for free-standing solid-state electrolytes.