| CPC H01M 50/375 (2021.01) [C08F 210/02 (2013.01); H01M 50/105 (2021.01); H01M 50/3425 (2021.01); C08F 2500/08 (2013.01); C08F 2500/33 (2021.01); C08F 2500/34 (2021.01); H01M 2200/10 (2013.01)] | 14 Claims |
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1. A secondary battery, comprising:
an electrode assembly;
an electrode lead attached to the electrode assembly;
a case configured to receive the electrode assembly therein;
a lead film configured to surround a part of an outer surface of the electrode lead, the lead film being interposed between the electrode lead and the case;
a vent region formed in at least a part of the case; and
a vent member inserted into the vent region, wherein the vent member contains linear low-density polyethylene having a poly dispersity index (PDI) of from 2.6 to 4,
wherein the vent member has a maximum sealing strength of less than 6 kgf/15 mm at from 100° C. to 120° C. and a maximum sealing strength of 6 kgf/15 mm or more at room temperature to 60° C.,
wherein the case includes a sealing portion formed to seal the electrode assembly, the sealing portion contains a sealant resin, and the linear low-density polyethylene has a lower melting point than the sealant resin,
wherein a difference between a crystallization temperature of the sealant resin and a crystallization temperature of linear low-density polyethylene is 10° C. or less,
wherein the linear low-density polyethylene is made by polymerizing in the presence of a metallocene catalyst, and wherein the linear low-density polyethylene has a crystallization temperature of 90° C. to 115° C.
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