A rechargeable battery comprising: an electrode assembly comprising a first electrode, a separator, and a second electrode; a case housing the electrode assembly wherein the case comprises: a bottom supporting the electrode assembly, the bottom being opposite to an opening; a side wall extending from the bottom along a periphery of the bottom thereby forming the opening opposite to the bottom; a cover closing the opening in the case; and an electrode terminal mounted to a terminal opening in the case and electrically connected to the second electrode characterized in that the side wall has the terminal opening, the bottom supports a flat side surface of the electrode assembly, the opening is in a plane parallel to the flat side surface of the electrode assembly and the case is electrically connected to the first electrode wherein the electrode terminal and the second electrode are formed to be insulated from the case, wherein the side wall comprises: a first long side wall and a second long side wall parallel to the first long side wall; and a first short side wall and a second short side wall parallel to the first short side wall, the first short side wall and the second short side wall each connected to the first long side wall and the second long side wall, wherein the first long side wall has the terminal opening, the rechargeable battery further comprising a first lead tab connected to the first electrode of the electrode assembly and connected to an inside surface of the first long side wall by welding, wherein the first long side wall further comprises a welding inducing portion protruded toward the first lead tab from an inside surface thereof and welded to the first lead tab wherein the electrode terminal comprises: a plate terminal on an outside of the first long side wall and aligned with the terminal opening; and a rivet terminal connected to the electrode assembly via a second lead tab, extending through the terminal opening, and fastened to the plate terminal. an electrode assembly comprising a first electrode, a separator, and a second electrode; a case housing the electrode assembly wherein the case comprises: a bottom supporting the electrode assembly, the bottom being opposite to an opening; a side wall extending from the bottom along a periphery of the bottom thereby forming the opening opposite to the bottom; a cover closing the opening in the case; and an electrode terminal mounted to a terminal opening in the case and electrically connected to the second electrode characterized in that the side wall has the terminal opening, the bottom supports a flat side surface of the electrode assembly, the opening is in a plane parallel to the flat side surface of the electrode assembly and the case is electrically connected to the first electrode wherein the electrode terminal and the second electrode are formed to be insulated from the case, wherein the side wall comprises: a first long side wall and a second long side wall parallel to the first long side wall; and a first short side wall and a second short side wall parallel to the first short side wall, the first short side wall and the second short side wall each connected to the first long side wall and the second long side wall, wherein the first long side wall has the terminal opening, the rechargeable battery further comprising a first lead tab connected to the first electrode of the electrode assembly and connected to an inside surface of the first long side wall by welding, wherein the first long side wall further comprises a welding inducing portion protruded toward the first lead tab from an inside surface thereof and welded to the first lead tab wherein the electrode terminal comprises: a plate terminal on an outside of the first long side wall and aligned with the terminal opening; and a rivet terminal connected to the electrode assembly via a second lead tab, extending through the terminal opening, and fastened to the plate terminal. a first long side wall and a second long side wall parallel to the first long side wall; and a first short side wall and a second short side wall parallel to the first short side wall, the first short side wall and the second short side wall each connected to the first long side wall and the second long side wall, wherein the first long side wall has the terminal opening, the rechargeable battery further comprising a first lead tab connected to the first electrode of the electrode assembly and connected to an inside surface of the first long side wall by welding, wherein the first long side wall further comprises a welding inducing portion protruded toward the first lead tab from an inside surface thereof and welded to the first lead tab wherein the electrode terminal comprises: a plate terminal on an outside of the first long side wall and aligned with the terminal opening; and a rivet terminal connected to the electrode assembly via a second lead tab, extending through the terminal opening, and fastened to the plate terminal. a plate terminal on an outside of the first long side wall and aligned with the terminal opening; and a rivet terminal connected to the electrode assembly via a second lead tab, extending through the terminal opening, and fastened to the plate terminal.