A battery module comprising: an enclosure comprising an interior surface, the interior surface defined by a first endplate and a second endplate extending between a first side wall and a second side wall and a top plate and a bottom plate, two or more battery cells disposed in the interior space of the enclosure; one or more spacer elements disposed between adjacent battery cells, each of the spacer elements comprising at least one thermal capacitive layer and at least one insulation layer; and a plurality of separate edge elements disposed along an interior surface of the enclosure, wherein the edge element comprises a material that is compressible and has an onset temperature of chemical decomposition greater than about 100 °C; wherein the edge element comprises a silicone polymer; and wherein each of the spacer elements contacts one of the plurality of separate edge elements such that a seal is formed by the edge elements between the spacer element and the interior surface of the enclosure thermally isolating the adjacent battery cells.