A battery module , comprising a sub module including a plurality of battery cells ; a lower housing to receive the sub module therein and having an opening (O); a first housing cover coupled to the lower housing , covering the opening (O) of the lower housing , and having a gas inlet (H1); a second housing cover coupled to the first housing cover from above to form a gas receiving space therebetween, and having a gas outlet (H2); and a variable partition structure using hinges installed in the gas receiving space to partition the gas receiving space to define a gas exhaust path (P) to increase a movement path of a flame entering together with gas occurred in the sub module and entering the gas receiving space through the gas inlet (H1), wherein the variable partition structure using hinges includes at least one hinge structure and at least two partition structures , the hinge structure includes a hinge axis in the shape of a cylindrical rod and hinge caps inserted and fixed to two ends of the hinge axis , and the two partition structures are coupled rotatably around the hinge axis , characerized in that the partition structure has a body in the shape of a small plate, a first handle structure at one end of the body , and a second handle structure at the other end, the first handle structure having a groove through which the hinge axis passes and the second handle structure having two grooves through which the hinge axis passes, the second handle structure of any one partition structure and the first handle structure of another partition structure are assembled with each other such that the grooves are vertically aligned, and the partition structures are connected to each other by inserting the hinge axis into the grooves. a sub module including a plurality of battery cells ; a lower housing to receive the sub module therein and having an opening (O); a first housing cover coupled to the lower housing , covering the opening (O) of the lower housing , and having a gas inlet (H1); a second housing cover coupled to the first housing cover from above to form a gas receiving space therebetween, and having a gas outlet (H2); and a variable partition structure using hinges installed in the gas receiving space to partition the gas receiving space to define a gas exhaust path (P) to increase a movement path of a flame entering together with gas occurred in the sub module and entering the gas receiving space through the gas inlet (H1), wherein the variable partition structure using hinges includes at least one hinge structure and at least two partition structures , the hinge structure includes a hinge axis in the shape of a cylindrical rod and hinge caps inserted and fixed to two ends of the hinge axis , and the two partition structures are coupled rotatably around the hinge axis , characerized in that the partition structure has a body in the shape of a small plate, a first handle structure at one end of the body , and a second handle structure at the other end, the first handle structure having a groove through which the hinge axis passes and the second handle structure having two grooves through which the hinge axis passes, the second handle structure of any one partition structure and the first handle structure of another partition structure are assembled with each other such that the grooves are vertically aligned, and the partition structures are connected to each other by inserting the hinge axis into the grooves. <EOS>