A battery module , comprising: a cell assembly including a plurality of battery cells ; a lower case having an open top and an accommodation space (S1) in which the cell assembly is received; an upper case which is coupled to the lower case to cover the open top of the lower case, the upper case having a connection hole (H1) in communication with the accommodation space; an upper cover which is coupled to the upper case to cover the top of the upper case, wherein part of the upper cover is spaced apart from the upper case to form a buffer space (S2), and the upper cover has an outlet (H2) in communication with the buffer space; and a partition which is provided in the buffer space, the partition having at least part extended to form a movement passage for movement of gas and flame which extends from the connection hole to the outlet, and configured to adjust an extension direction of the part, wherein the partition includes: a barrier which is extended in at least one direction; and a hinge which is hinge-coupled to an end of the barrier to allow the barrier to rotatably move; wherein the partition further includes an extension part configured to protrude in at least one direction from the barrier, and the barrier includes an accommodation groove (131h1) which has a space into which the extension part is inserted and configured to allow the extension part to move in a protrusion direction when the extension part is inserted into the accommodation groove. a cell assembly including a plurality of battery cells ; a lower case having an open top and an accommodation space (S1) in which the cell assembly is received; an upper case which is coupled to the lower case to cover the open top of the lower case, the upper case having a connection hole (H1) in communication with the accommodation space; an upper cover which is coupled to the upper case to cover the top of the upper case, wherein part of the upper cover is spaced apart from the upper case to form a buffer space (S2), and the upper cover has an outlet (H2) in communication with the buffer space; and a partition which is provided in the buffer space, the partition having at least part extended to form a movement passage for movement of gas and flame which extends from the connection hole to the outlet, and configured to adjust an extension direction of the part, wherein the partition includes: a barrier which is extended in at least one direction; and a hinge which is hinge-coupled to an end of the barrier to allow the barrier to rotatably move; wherein the partition further includes an extension part configured to protrude in at least one direction from the barrier, and the barrier includes an accommodation groove (131h1) which has a space into which the extension part is inserted and configured to allow the extension part to move in a protrusion direction when the extension part is inserted into the accommodation groove. a barrier which is extended in at least one direction; and a hinge which is hinge-coupled to an end of the barrier to allow the barrier to rotatably move; wherein the partition further includes an extension part configured to protrude in at least one direction from the barrier, and the barrier includes an accommodation groove (131h1) which has a space into which the extension part is inserted and configured to allow the extension part to move in a protrusion direction when the extension part is inserted into the accommodation groove. <EOS>