A battery assembly including a frame including a pair of side plates that include a plurality of guide grooves and a bottom plate connected to the side plates; a plurality of barriers each including a pair of side panels, a lower panel, an upper panel, a plurality of protrusions that are protruded from the side panels, and a dividing panel, wherein the plurality of protrusions are inserted into the plurality of guide grooves to slidably move along the guide grooves upon being mounted on the frame, and a plurality of batteries that are respectively accommodated by the barriers, wherein the barriers are stacked such that the dividing panels of the adjacent barriers face one another.