Method of manufacturing porous separator comprising elastic material, porous separator manufactured by the method, and secondary battery comprising the separator
View Patent ↗Disclosed is a method of manufacturing a porous separator including an elastic material, and a separator manufactured by the method. The separator includes an elastic material being uniformly dispersed in a polymer at a weight ratio of 40:60 to 5:95, and a value of elongation at break in a low tensile strength direction at room temperature is greater than or equal to 250%. In addition, the method of manufacturing a porous separator includes forming an extruded sheet by extruding a mixture of a polymer and an elastic material at a weight ratio of 95:5 to 60:40, forming a film by annealing and stretching the extruded sheet, and forming a porous separator by heat setting the stretched film. Accordingly, a thermal shrinkage ratio of the film is reduced and an elongation at break is greatly increased, to provide a porous separator with improved stability.
1. A porous separator comprising a mixture of an elastic material and a polymer resin,
wherein, in the mixture, the elastic material comprises an elastic copolymer including ethylene-octene copolymer present in an amount of 5 wt % to less than 10 wt % and the polymer resin comprises polypropylene present in an amount of more than 90 wt % to 95 wt %,
wherein, in the mixture, the elastic material is uniformly dispersed in the polymer resin,
wherein a value of elongation at break in a low tensile strength direction at room temperature is greater than or equal to 250%, and
wherein the porous separator is uniaxially stretched.
2. The porous separator according to claim 1 , wherein the uniaxial stretch is carried out in a machine direction (MD).
3. A secondary battery comprising a cathode, an anode, and a porous separator according to claim 1 interposed between the cathode and the anode.
4. The secondary battery according to claim 3 , wherein the secondary battery is a lithium secondary battery.