A battery pack includes a plurality of battery cell stacks, each battery cell stack including a plurality of battery cells; a battery pack case configured to receive the plurality of battery cell stacks, wherein the battery pack case includes a pack case space portion located adjacent to a first side of a first battery cell stack; and a beam located adjacent to a second side of the first battery cell stack; the battery pack case being hollow and configured to store a coolant; and an outlet in the battery pack case.