NONAQUEOUS ELECTROLYTE SECONDARY BATTERY SEPARATOR

• US 20180254455A1
• Filed: 03/02/2018
• Published: 09/06/2018
• Est. Priority Date: 03/03/2017
• Status: Active Grant

• Current Assignee: Sumitomo Chemical Company Limited
• Original Assignee: Sumitomo Chemical Company Limited
• Inventors: YOSHIMARU, Chikae, HARA, Syusaku, YASHIKI, Daizaburo
• Granted Patent: US 10,566,594 B2
• Time in Patent Office: Days
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 50/403 Manufacturing processes of separators, membranes or diaphragms
• CPC Class Codes: H01M 50/417 Polyolefins
• CPC Class Codes: H01M 50/489 Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
• CPC Class Codes: H01M 50/491 Porosity
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention provides a nonaqueous electrolyte secondary battery separator which is excellent in cycle characteristic. The nonaqueous electrolyte secondary battery separator includes a polyolefin porous film in which a difference between (i) a porosity calculated from a continuous image which is formed so as to extend from a surface to an inside of the polyolefin porous film in a thickness direction and in which a void part and a resin part are shown at respective two gray levels and (ii) a porosity calculated from a thickness, a weight per unit area, and a real density of the polyolefin porous film is 4% to 20%.

Claims

1. A nonaqueous electrolyte secondary battery separator including a polyolefin porous film, wherein:

a difference between an average porosity calculated from a continuous image of the polyolefin porous film and a porosity calculated based on a thickness, a weight per unit area, and a real density of the polyolefin porous film is 4% to 20%, the continuous image being obtained by FIB-SEM measurement with a magnification of 6500 times and image analysis, the continuous image having a size of 256 pix×

256 pix along a surface of said nonaqueous electrolyte secondary battery separator where 1 pix is 19.2 nm, a thickness of the continuous image being equal to a thickness of said nonaqueous electrolyte secondary battery separator, the continuous image being formed so as to extend from the surface to an inside of said nonaqueous electrolyte secondary battery separator in a thickness direction, and, in the continuous image, a void part and a resin part of the polyolefin porous film being shown at respective two gray levels.

2. The nonaqueous electrolyte secondary battery separator as set forth in claim 1, wherein a compressive elastic modulus of said nonaqueous electrolyte secondary battery separator is not less than 1600 kPa.

3. A nonaqueous electrolyte secondary battery laminated separator comprising:

a nonaqueous electrolyte secondary battery separator recited in claim 1; and

an insulating porous layer.

4. A nonaqueous electrolyte secondary battery member comprising:

a positive electrode;

a nonaqueous electrolyte secondary battery separator recited in claim 1; and

a negative electrode,

the positive electrode, the nonaqueous electrolyte secondary battery separator, and the negative electrode being disposed in this order.

5. A nonaqueous electrolyte secondary battery comprising:

a nonaqueous electrolyte secondary battery separator recited in claim 1.

6. A nonaqueous electrolyte secondary battery member comprising:

a positive electrode;

a nonaqueous electrolyte secondary battery laminated separator recited in claim 3; and

a negative electrode,

the positive electrode, the nonaqueous electrolyte secondary battery laminated separator, and the negative electrode being disposed in this order.

7. A nonaqueous electrolyte secondary battery comprising:

a nonaqueous electrolyte secondary battery laminated separator recited in claim 3.