BATTERY SEPARATOR

摘要

A battery separator includes a microporous polyolefin membrane and a modifying porous layer laminated on at least one surface of the microporous polyolefin membrane, wherein the microporous polyolefin membrane comprises a polyethylene resin, and the modifying porous layer is laminated on at least one surface of the microporous polyolefin membrane having (a) a shutdown temperature of 135° C. or lower, (b) a rate of air resistance change of 1×104 sec/100 cc/° C. or more, and (c) a transverse shrinkage rate at 130° C. of 20% or less.

主权项

1. A battery separator comprising a microporous polyolefin membrane and a modifying porous layer laminated on at least one surface of the microporous polyolefin membrane, the modifying porous layer containing a resin for that provides or improves adhesion to electrode material, wherein the microporous polyolefin membrane comprises a polyethylene resin and has (a) a shutdown temperature (temperature at which the air resistance measured while heating at a temperature rise rate of 5° C./min reaches 1×106 sec/100 cc) of 135° C. or lower, (b) a rate of air resistance change (a gradient of a curve representing dependency of air resistance on temperature at an air resistance of 1×104 sec/100 cc) of 1×104 sec/100 cc/° C. or more, and (c) a transverse shrinkage rate at 130° C. (measured by thermomechanical analysis under a load of 2 gf and at a temperature rise rate of 5° C./min) of 20% or less, wherein the polyethylene resin has a percentage of integrated endothermic amount up to 125° C. in the crystal melting heat quantity measured by differential scanning calorimetry at a temperature rise rate of 10° C./min of 20% or less, and a temperature of 135° C. or lower when the endothermic amount reaches 50% of the crystal melting heat.