Abstract: A battery cell stack casing includes casing walls defining a housing interior for receiving a battery cell stack, a first end plate provided between the walls at a first end of the casing to close a first end of the housing interior, and a second end plate provided between the walls at a second end of the casing to close a second end of the housing interior. The casing walls have a multi-layer structure that includes, an inner layer having a first side facing into the housing interior and a second opposite side, an outer layer spaced outwardly from the second side of the inner layer, an air or vacuum-filled thermally insulating volume defined between the second side of the inner layer and the outer layer, and a layer of intumescent material provided on the first side of the inner layer.