A battery includes a case accommodating an electrode assembly, the case including an opening at one end and including at least one sidewall, the sidewall having a coupling portion adjacent to the opening, a cap plate that closes the opening, the cap plate having an upper surface, the coupling portion of the sidewall connecting the cap plate to the case, the coupling portion including a top surface of the sidewall, the cap plate overlying a first portion of the top surface of the sidewall, such that the upper surface of the cap plate is entirely above top surface of the sidewall, and a welding bead contacting the cap plate and a second portion of the top surface of the sidewall, the second portion of the top surface being between the first portion and an outer surface of the sidewall.