Battery, battery separator and method for producing battery separator

• US 9,059,453 B2
• Filed: 01/16/2013
• Issued: 06/16/2015
• Est. Priority Date: 05/30/2012
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Sumida, Hiroto, Kurokawa, Takahiro, Yamaguchi, Takayoshi, Mitsushima, Takatoshi
• Primary Examiner(s): Cano, Milton I
• Assistant Examiner(s): ZENG, LINGWEN R
• Application Number:
  US14/110,419
• Publication Number:
  US 20140227602A1
• Time in Patent Office: 881 Days
• Field of Search: 429/129, 429/246, 429/247, 156/276, 156/324
• US Class Current: 1/1
• CPC Class Codes: B32B 37/20 involving the assembly of continuous webs only
• CPC Class Codes: B32B 37/24 with at least one layer not being coherent before laminating, e.g. made up from granular material sprinkled onto a substrate B32B37/15 takes precedence
• CPC Class Codes: H01M 10/052 Li-accumulators
• 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 50/44 Fibrous material
• CPC Class Codes: H01M 50/454 comprising a non-fibrous layer and a fibrous layer superimposed on one another
• CPC Class Codes: H01M 50/46 Separators, membranes or diaphragms characterised by their combination with electrodes
• 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
• CPC Class Codes: Y10T 29/49115 including coating or impregnating

Abstract

A battery includes a positive electrode, a negative electrode, a separator interposed therebetween, and an electrolyte. The separator includes a plurality of nanofibers and has a form of a sheet having a first surface and a second surface opposite thereto. When the average maximum fiber diameter of the nanofibers in the plane direction of the separator is compared between in vicinities of the first and second surfaces and at a center portion in the thickness direction of the separator, average maximum fiber diameters Ds1 and Ds2 of the nanofibers in the vicinity of the first and second surfaces arc smaller than an average maximum fiber diameter Dc of the nanofibers at the center portion in the thickness direction of the separator.

Claims

1. A method for producing a battery separator in a production line, in which:

long first and second substrate sheets are conveyed from upward toward downward of first and second lines of the production line, respectively, to form first and second porous sheets on principal surfaces of the first and second substrate sheets on the upstream side of the lines, respectively; and

the first and second porous sheets are joined face to face on the downstream side of the lines, the method comprising the steps of;

(i) conveying the first and second substrate sheets into nanofiber-forming spaces on the upstream side of the first and second lines, respectively;

(ii) in the nanofiber-forming spaces, forming nanofibers by electrostatic force from a raw material solution including a solvent and a resin raw material dissolved in the solvent, and depositing the formed nanofibers on the principal surfaces of the conveyed first and second substrate sheets, respectively, to form first and second porous sheets each having a plurality of nanofibers;

(iii) removing the first and second substrate sheets from the conveyed first and second porous sheets, on the downstream side of the first and second lines; and

(iv) joining the conveyed first and second porous sheets to each other on the further downstream side of the first and second lines, with surfaces having been in contact with the principal surfaces of the first and second substrate sheets facing each other, to form a nanofiber sheet,

wherein the steps (i) to (iv) are continuously performed in the production line.

2. The method for producing a battery separator according to claim 1, wherein in the step (iv), the first and second porous sheets are joined to each other while the solvent is contained at least at or near the surfaces having been in contact with the principal surfaces of the first and the second substrate sheets, so that the nanofibers of the first porous sheet and the nanofibers of the second porous sheet are welded to one another.