A rechargeable battery comprising: an electrode assembly comprising a first electrode, a second electrode, and a separator between the first electrode and the second electrode; a case comprising an inner space to accommodate the electrode assembly and having an opening at a side thereof; a cap plate coupled to the opening of the case and comprising a terminal hole to expose the inner space; and an electrode terminal electrically connected to the electrode assembly through the terminal hole and overlapping the cap plate, wherein the cap plate and the electrode terminal are made of different metals, wherein the cap plate is electrically connected to the electrode assembly, and the cap plate and the electrode terminal are respectively electrically connected to different electrodes (11, 12) of the electrode assembly, wherein the cap plate is made of a metal having a higher ionization tendency than that of an electrode (11, 12) of the electrode assembly electrically connected to the cap plate, wherein the cap plate is made of a metal having a lower ionization tendency than that of the electrode terminal, wherein the electrode terminal comprises: a flange portion configured to cover the terminal hole and overlapping the cap plate; and a protrusion integrally formed with the flange portion to protrude from the flange portion toward the terminal hole, wherein an outer surface of the protrusion comprises a curved surface and an inclined surface, a distance from the curved surface to an end portion of the cap plate exposed to the terminal hole is shorter than a distance from the inclined surface to an end portion of the cap plate exposed to the terminal hole, and the distance from the inclined surface to the end portion of the cap plate exposed to the terminal hole becomes longer toward an end portion of the inclined surface. an electrode assembly comprising a first electrode, a second electrode, and a separator between the first electrode and the second electrode; a case comprising an inner space to accommodate the electrode assembly and having an opening at a side thereof; a cap plate coupled to the opening of the case and comprising a terminal hole to expose the inner space; and an electrode terminal electrically connected to the electrode assembly through the terminal hole and overlapping the cap plate, wherein the cap plate and the electrode terminal are made of different metals, wherein the cap plate is electrically connected to the electrode assembly, and the cap plate and the electrode terminal are respectively electrically connected to different electrodes (11, 12) of the electrode assembly, wherein the cap plate is made of a metal having a higher ionization tendency than that of an electrode (11, 12) of the electrode assembly electrically connected to the cap plate, wherein the cap plate is made of a metal having a lower ionization tendency than that of the electrode terminal, wherein the electrode terminal comprises: a flange portion configured to cover the terminal hole and overlapping the cap plate; and a protrusion integrally formed with the flange portion to protrude from the flange portion toward the terminal hole, wherein an outer surface of the protrusion comprises a curved surface and an inclined surface, a distance from the curved surface to an end portion of the cap plate exposed to the terminal hole is shorter than a distance from the inclined surface to an end portion of the cap plate exposed to the terminal hole, and the distance from the inclined surface to the end portion of the cap plate exposed to the terminal hole becomes longer toward an end portion of the inclined surface. a flange portion configured to cover the terminal hole and overlapping the cap plate; and a protrusion integrally formed with the flange portion to protrude from the flange portion toward the terminal hole, wherein an outer surface of the protrusion comprises a curved surface and an inclined surface, a distance from the curved surface to an end portion of the cap plate exposed to the terminal hole is shorter than a distance from the inclined surface to an end portion of the cap plate exposed to the terminal hole, and the distance from the inclined surface to the end portion of the cap plate exposed to the terminal hole becomes longer toward an end portion of the inclined surface.