Toray Battery Separator Film Co., Ltd.

Toray Industries, Inc.

Sanyo Electronics Co., Ltd.

Masanori Nakamura

Michihiko Irie

Naoki Mizuno

Ken Shimizu

Yoshitaka Ayuzawa

Naoki Imachi

Yasunori Baba

Atsushi Nakajima

A method produces a composite porous membrane including a porous membrane A formed of a polyolefin-based resin; and a porous membrane B containing a heat-resistant resin and laminated on the porous membrane A, including: (i) applying a heat-resistant resin solution onto a base film, followed by passing the coated film through a low-humidity zone, and then through a high-humidity zone to form a heat-resistant resin membrane on the base film; and (ii) bonding together the heat-resistant resin membrane formed in step (i) and a porous membrane A formed of a polyolefin-based resin, followed by converting the heat-resistant resin membrane into a porous membrane B by immersion in a solidification bath, and washing and drying the same to obtain the composite porous membrane.

Method of producing composite porous membrane

A composite porous membrane is a composite porous membrane, wherein a porous membrane B including a heat-resistant resin is laminated on the surface of a polypropylene resin of an outermost layer of a porous membrane A composed of at least one layer, wherein at least one of the outermost layers comprises the polypropylene resin. The composite porous membrane satisfies a particular range of peeling strength at the interface between the porous membrane A and the porous membrane B and a particular range of difference between air resistance of the whole composite porous membrane and air resistance of the porous membrane A, provided that the porous membrane A satisfies a particular range of average pore size and porosity.

Composite porous membrane and method of producing the same

A battery separator includes a porous membrane A including a polyethylene resin, and a porous membrane B laminated thereon including a heat resistant resin and inorganic particles or cross-linked polymer particles, wherein the porous membrane A satisfies expressions (a) to (c), and the entire battery separator satisfies expressions (d) to (f).

Battery separator, and battery separator manufacturing method

A battery separator includes a porous membrane A with a thickness of less than 10 &#x3bc;m including a polypropylene resin, and a porous membrane B laminated thereon including a heat resistant resin and inorganic particles or cross-linked polymer particles, wherein the porous membrane A satisfies a specific range of thickness, average pore size, and porosity, and the entire battery separator satisfies a specific range of thickness, peeling strength at the interface between the porous membrane A and the porous membrane B, and difference in air resistance between the entire battery separator and the porous membrane A.

To obtain a separator for a nonaqueous electrolyte battery that has an excellent nonaqueous electrolyte permeability into an electrode and an excellent electrolyte retentivity of the electrode and achieves a large capacity, a high energy density and a good high-temperature charge characteristic. A separatorused for a nonaqueous electrolyte battery is formed by disposing a porous layermade of inorganic fine particles and a resin binder on a porous separator substrate, the resin binder is made of at least one resin selected from the group consisting of polyimide resins, polyamide resins and polyamideimide resins and the molecular chain of the resin has a halogen atom content of 10% to 30% by weight, and the content of the resin binder in the porous layer is 5% by weight or more.

Growing community of inventors

Nasushiobara, Japan

Masanori Nakamura