A rechargeable battery includes an electrode assembly having a positive electrode, a negative electrode and a separator separating the positive terminal and the negative terminal. A casing includes a spatial area for receiving and holding the electrode assembly. A heat dissipating body is provided for receiving and holding the casing. A convex part of the heat dissipating body is formed supporting the electrode assembly within the heat dissipating body so that uniform pressure is applied to the entire surface of the rechargeable battery. A battery module may include multiple unit rechargeable batteries. A heat dissipating barrier may be disposed adjacent to each unit rechargeable battery and have a convex part for applying pressure to the unit rechargeable battery.