Battery separator and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-2016336569-A1
Application number	US-201415110389-A
Country	US
Kind code	A1
Filing date	Dec 16, 2014
Priority date	Jan 10, 2014
Publication date	Nov 17, 2016
Grant date	—

Abstract

A battery separator is disclosed. The battery separator includes a polyolefin porous membrane which has a plurality of protrusions including a polyolefin. The protrusions are interspersed randomly on at least one surface of the polyolefin porous membrane at a density of not less than 3 protrusions/cm2 and not greater than 200 protrusions/cm2. The protrusions have a size W, where 5 μm≦W≦50 μm, and the protrusions have a height H, where 0.5 μm≦H. The battery separator also includes a modified porous layer, including a fluorine-based resin, and a plurality of inorganic particles laminated on the at least one surface of the polyolefin porous membrane. A concentration of the inorganic particles is not less than 40 wt. % and is less than 80 wt. %.

First claim

1 . A battery separator comprising:
a polyolefin porous membrane, comprising a plurality of protrusions comprising a polyolefin, wherein the protrusions are interspersed randomly on at least one surface of the polyolefin porous membrane at a density of not less than 3 protrusions/cm 2 and not greater than 200 protrusions/cm 2 , wherein the protrusions have a size W, wherein 5 μm≦W≦50 μm, wherein the protrusions have a height H, wherein 0.5 μm≦H; and a modified porous layer, comprising:
a fluorine-based resin, and
a plurality of inorganic particles laminated on the at least one surface of the polyolefin porous membrane, wherein a concentration of the inorganic particles is not less than 40 wt. % and is less than 80 wt. %.

2 . The battery separator according to claim 1 , wherein a thickness of the polyolefin porous membrane is not greater than 25 μm.

3 . The battery separator according to claim, wherein the inorganic particles comprise at least one of calcium carbonate, alumina, titania, barium sulfate, and boehmite.

4 . The battery separator according to claim 1 , wherein the battery separator is included in a lithium ion rechargeable battery.

5 . A method of manufacturing a battery separator, the method comprising:
preparing a polyethylene resin solution by adding a forming solvent to a polyethylene resin and subsequently melt-kneading the solution; forming a gel-like molded product by:
extruding the polyethylene resin solution through a die,
cooling the extrudate with a cooling roller, and
removing the forming solvent from a surface of the cooling roller;
forming a stretched and molded material by stretching the gel-like molded product in a machine direction and in a width direction; forming a porous molded material by extracting and removing the forming solvent from the stretched and molded material followed by drying the molded material; forming a polyolefin porous membrane by treating the porous molded material with heat; using a coating solution containing a fluorine-based resin, inorganic particles, and a solvent capable of dissolving or dispersing the fluorine-based resin to form , forming a laminated film on a surface of the polyolefin porous membrane, wherein the surface of the polyolefin porous membrane is in contact with the cooling roller; and drying the laminated film.

6 . The method of manufacturing a battery separator according to claim 5 , wherein the forming solvent is removed from the surface of the cooling roller with a doctor blade.

Assignees

• Toray Battery Separator Film

Inventors

• Mizuno Naoki
• Matano Koichi

Classifications

• B32B27/32 Primary

  comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)} · CPC title

• B32B2264/104

  Oxysalt, e.g. carbonate, sulfate, phosphate or nitrate particles · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• B32B3/266 Primary

  characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12 · CPC title

• B29C48/914

  Cooling drums · CPC title