BATTERY STACK CASING

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. The casing also include 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 include: 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; a thermally insulating volume defined between the second side of the inner layer and the outer layer, the thermally insulating material containing a low density thermally insulative material e.g., foam or other insulative material; and a layer of intumescent material provided on the first side of the inner layer.