LI SECONDARY BATTERY FOR IMPROVING BONDABILITY OF TAB TO POLYMER FILM

摘要

Provided is a lithium secondary battery, which shows improved sealability in the vicinity of a tab, and thus prevents infiltration of foreign materials such as moisture into a battery and leakage of an electrolyte. The lithium secondary battery comprises: an electrode assembly having at least one tab(32) protruding out from one surface; a casing for surrounding and sealing the electrode assembly and the tab except the front end of the tab; and a polymer film(40) disposed in an interface between the casing and the tab for increasing the adhesion to the tab. In the lithium secondary battery, when the tab is formed to have a predetermined thickness(d), at least one of the top surface and the bottom surface of the tab forms an obtuse angle with an adjacent surface so as to improve the bondability between the tab and the polymer.