ELECTRODE ASSEMBLY HAVING IMPROVED SAFETY OF USE BY MEANS OF STRUCTURE IN WHICH LOCAL SITE IN EXTERIOR MATERIAL IS REINFORCED WITH ELASTIC POLYMER FILM, AND LITHIUM-ION SECONDARY BATTERY HAVING SAME

A lithium ion secondary battery according to the present disclosure includes: an electrode assembly; and a case having a structure in which upper stamped portions and lower stamped portions are repeatedly stamped to cover the outside of the electrode assembly, and the upper stamped portions and the lower stamped portions form a corrugated pattern, and the electrode assembly includes: one or more unit cells each equipped with a pair of electrodes having different polarities with a separator interposed therebetween; an electrode mixture coated on one or both surfaces of the pair of electrodes; and electrode tabs protruded from the respective electrodes and not coated with the electrode mixture, and the electrode tabs include an electrode parallel connection tab and an electrode lead connection tab, and any one or more of the electrode parallel connection tab and the electrode lead connection tab is formed on the electrodes, and an elastic polymer film is overlapped on a local portion in the case.