A battery pack according to an embodiment of the present invention includes a first cover, a second cover coupled to the first cover in a direction crossing the first cover, a third cover coupled to portion of each of the first cover and the second cover, a first sealing member disposed along a first coupling area of the first cover and the second cover, and a second sealing member disposed along a second coupling area between the first and second covers and the third cover, wherein the first sealing member extends to a contact area in which the first sealing member contacts the second sealing member along a boundary between the first cover and the second cover.

A secondary battery includes an electrode assembly, a case that accommodates the electrode assembly, a cap plate coupled to an opening of the case, an electrode terminal installed on the cap plate, a lead tab that electrically connects the electrode assembly to the electrode terminal, and a protective member between the electrode assembly and the case, the protective member including expanded powdery structures.

A cap assembly may include a cap plate having a through hole formed therein, a rivet terminal that may be inserted into the through hole and placed through the cap plate, a terminal plate that may be joined to one end of the rivet terminal on an upper surface of the cap plate, and a gasket that may be inserted into the through hole and insulates the cap plate and the rivet terminal, the rivet terminal may have a maximum radial width less than the through hole.

A battery module including a battery cell stack in which a plurality of battery cells are stacked in a first direction, and a body located on one side of the battery cell stack, wherein the body includes a cavity configured to receive an extinguishing material, the cavity having an inlet and an outlet, and at least one rupture part for one of the inlet and outlet.

A battery module including a battery cell stack in which a plurality of battery cells are stacked in a first direction, and a body located on one side of the battery cell stack, wherein the body includes a cavity configured to receive an extinguishing material, the cavity having an inlet and an outlet, and at least one rupture part for one of the inlet and outlet.

A secondary battery includes an electrode assembly configured to have a structure in which a separator is interposed between a positive electrode and a negative electrode, a battery case having formed therein a receiving portion configured to receive the electrode assembly, electrode leads configured to protrude outwards from the battery case, and lead films attached to opposite surfaces of each of the electrode leads, wherein each of the lead films includes a luminous material.