Separator for lithium-ion secondary battery
AssigneesAsahi Kasei Kabushiki Kaisha, Celgard, LLC
InventorsTakahiko Kondo, Kazunori Uchida, Shinya Hamasaki
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Abstract
Problem: The invention provides a separator for a lithium-ion secondary battery exhibiting excellent strength, wettability with nonaqueous electrolyte solutions, voltage endurance and cycle characteristics in lithium-ion secondary batteries, and a method of increasing the puncture depth of the separator. Solution: A separator for a lithium-ion secondary battery is formed of a microporous film comprising a polyolefin resin (A) as a major component, and a resin (B), at least portions of the surfaces of the micropores in the microporous film being coated with resin (B).
Claims18
A separator for a lithium-ion secondary battery, comprising a microporous film, wherein the microporous film comprises:
- a polyolefin resin (A) comprising polypropylene as a major component;
- and
- interior surfaces of micropores in the microporous film are coated with a resin (B) different from the polyolefin resin (A), and a coated amount of the resin (B) is 5 to 70 weight % based on the total resin weight,
- wherein the resin (B) is a C3 unit-containing polyolefin copolymer, or a polyolefin with an elastic modulus of 110 to 520 MPa at 25° C. and a melting point of no higher than 130° C.;
- wherein the separator has a porosity of 41% to 58%, and an air permeability of 161 sec/100 cc to 244 sec/100 cc, and
- wherein the separator is free of a fluorine-containing resin binder.
Dependencies are inferred from the claim text.