BATTERY MODULE AND BATTERY PACK WITH IMPROVED SAFETY

Provided is a battery module or the like with an improved structure to improve safety when a thermal event occurs in the battery module. A battery module according to an aspect of the present disclosure includes a cell assembly including one or more battery cells, a module case having an inner space in which the cell assembly is accommodated, and an expansion member located in the module case, and configured to fill at least a part of an empty space in the module case by being expanded in volume when heat is supplied.