An electrode assembly is provided. The electrode assembly has a plurality of electrode plates having one or both sides of each of the electrode plates that are coated with an electrode active material and are stacked with a separator interposed between the respective electrode plates. The separator includes a surplus outer periphery of a size greater than the outer periphery of an electrode plate, an electrode tab which extends from the outer periphery of the electrode plate and protrudes outwardly beyond the outer periphery of the separator is formed on each electrode plate, and at least some of the separators forming the electrode assembly have an insulation-enhancing part for suppressing heat shrinkage of a separator formed in the surplus outer peripheries thereof which are adjacent to the respective electrode tabs.