SECONDARY BATTERY HAVING ELECTRODE WITH SELF CUTTING PART TO BE DESTRUCTED ON APPLICATION OF OVER-CURRENT

摘要

A secondary battery including an electrode terminal having a breaking portion is provided to allow the electrode terminal to be destroyed upon the generation of an over-current, in the case of a short and before the sealing portion of a casing is separated and ignitable components are ejected, thereby ensuring excellent safety of the battery. A secondary battery as a unit cell of a middle- or large-size battery pack comprises: a sheet-like battery casing(200) including a metal layer and a resin layer; an electrode assembly capable of repeating charge/discharge and sealed in the battery casing; and electrode terminals protruding out from the sealing portion of the battery casing, wherein the electrode terminal(411) has a breaking portion(431) at a predetermined distance(L) from the sealing portion(240), the breaking portion having a relatively smaller section(SA) as compared with other vertical sections(ST) of the electrode terminal so that the breaking portion is preferentially destroyed upon the generation of an over-current.