Secondary battery including one-way exhaust member

摘要

Disclosed herein is a plate-shaped secondary battery constructed in a structure in which an electrode assembly of a cathode/separator/anode structure is mounted in a battery case, and the battery case is sealed by thermal welding, wherein the secondary battery has at least one-way exhaust member, mounted at a sealed portion, formed at the outer circumference of an electrode assembly receiving part of the battery case, for allowing internal high-pressure gas to be exhausted out of a battery cell and preventing external gas from being introduced into the battery cell. The secondary battery according to the present invention has the effect of effectively exhausting internal high-pressure gas generated during the abnormal operation of the battery, such as overcharge, out of the battery case, while maintaining the sealability of the battery case, thereby simultaneously improving the efficiency and safety of the battery.

主权项

1. A plate-shaped secondary battery constructed in a structure in which an electrode assembly of a cathode/separator/anode structure is mounted in a battery case, and the battery case is sealed by thermal welding, wherein
the secondary battery has at least one-way exhaust member, mounted at a sealed portion, formed at the outer circumference of an electrode assembly receiving part of the battery case, for allowing internal high-pressure gas to be exhausted out of a battery cell and preventing external gas from being introduced into the battery cell, wherein the one-way exhaust member includes: a first film attached to the sealed portion, a porous film constructed in a structure in which the outer circumference, of the porous film, excluding an upper end opening of the one-way exhaust member, is coupled to the first film, and the upper end of the porous film is lower than that of the first film, a variable film constructed in a structure in which the outer circumference of the variable film, excluding the upper end opening of the one-way exhaust member, is coupled to the porous film, the lower end of the variable film is coupled to the porous film at a position where the lower end of the variable film is spaced apart from the lower end of the porous film by a predetermined width, and the upper end of the variable film is higher than that of the porous film, the variable film being made of a material more flexible than that of the porous film or having a thickness less than that of the porous film, and a second film constructed in a structure in which the second film is attached to the sealed portion at the opposite side of the first film, and the outer circumference of the second film, excluding the upper end opening of the one-way exhaust member, is coupled to the lower end of the variable film, wherein the variable film is movable between a position contacting the first film and a position separated from the first film, such that, when the variable film is in the position contacting the first film, the variable film prevents external gas from being introduced into the battery cell through the one-way exhaust member, and when the variable film is in the position separated from the first film, internal high-pressure gas can be exhausted out of a battery cell through the one-way exhaust member.