Provided is a secondary battery including an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The positive electrode includes a positive electrode non-coating portion that is not coated with an active material in a portion of a positive electrode collector. The negative electrode includes a negative electrode non-coating portion that is not coated with an active material in a portion of a negative electrode collector. The non-coating portions are disposed in at least one of upper and lower portions of the electrode assembly in a longitudinal direction of the electrodes. A positive electrode tab and a negative electrode tab are connected to the non-coating portions. The separator is a complex porous separator including a substrate coated with a binder polymer or an organic/inorganic mixture formed of a binder polymer and inorganic particles.