BATTERY MODULE, AND BATTERY PACK AND POWER STORAGE DEVICE INCLUDING SAME

A battery module includes a plurality of battery cells assemblies, each having a plurality of battery cells stacked on each other; and at least one cooling unit provided between the plurality of battery cells assemblies and filled with a predetermined coolant therein, the at least one cooling unit having at least one membrane member provided at one end thereof to be opened or closed according to a change of an internal pressure thereof.