# US 10,770,707 B2 · Battery separator and method of manufacturing same

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- Number: US 10,770,707 B2
- Document ID: US10770707B2
- Status: Granted
- Kind: B2
- Application number: 15/781,429
- Filed: 2016-11-14
- Published: 2018-12-20
- Granted: 2020-09-08
- Earliest claimed: 2015-12-04
- Assignees: Toray Industries, Inc.
- Applicants: Toray Industries, Inc.
- Inventors: Naoki Mizuno; Masami Sugata
- Web page: https://patentgrep.com/patent/US10770707B2

## CPC

- C08J 9/28: by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
- B01D 71/38: Polyalkenylalcohols; Polyalkenylesters; Polyalkenylethers; Polyalkenylaldehydes; Polyalkenylketones; Polyalkenylacetals; Polyalkenylketals
- B01D 71/40: Polymers of unsaturated acids or derivatives thereof, e.g. salts, amides, imides, nitriles, anhydrides, esters
- B29C 55/005: {characterised by the choice of materials}
- B29C 55/143: {firstly parallel to the direction of feed and then transversely thereto}
- B29D 7/01: Films or sheets
- B32B 3/26: characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids {(foam layer B32B5/18; layer of synthetic resin characterised by fillers that create voids or cavities B32B27/205); characterised by an apertured layer}
- B32B 5/32: {at least two} layers being foamed {and next to each other}
- B32B 7/02: Physical, chemical or physicochemical properties
- B32B 7/022: Mechanical properties
- B32B 27/08: of synthetic resin
- B32B 27/18: characterised by the use of special additives
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- B32B 27/327: {comprising polyolefins obtained by a metallocene or single-site catalyst}
- C08J 5/18: Manufacture of films or sheets
- C08J 7/0427: {with only one layer of a composition containing a polymer binder (with more layers C08J7/042)}
- C08J 7/043: Improving the adhesiveness of the coatings per se, e.g. forming primers (adhesives in the form of films or foils characterised by the primer layers between the polymer carriers and the adhesives C09J7/50)
- C08J 9/365: {Coating}
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 50/403: Manufacturing processes of separators, membranes or diaphragms
- H01M 50/406: Moulding; Embossing; Cutting
- H01M 50/417: Polyolefins
- H01M 50/426: Fluorocarbon polymers
- H01M 50/446: Composite material consisting of a mixture of organic and inorganic materials
- H01M 50/451: comprising layers of only organic material and layers containing inorganic material
- H01M 50/463: Separators, membranes or diaphragms characterised by their shape
- H01M 50/491: Porosity
- B01D 69/02: characterised by their properties
- B01D 2325/50: Membrane in gel form
- B29K 2027/16: {PVDF, i.e. polyvinylidene fluoride}
- B29K 2105/041: {Microporous}
- B29K 2503/04: Inorganic materials
- B29L 2031/3468: {Batteries, accumulators or fuel cells (battery cases B29L2031/7146)}
- B32B 2250/242: All polymers belonging to those covered by group B32B27/32
- B32B 2255/10: on synthetic resin layer or on natural or synthetic rubber layer
- B32B 2255/26: Polymeric coating
- B32B 2270/00: Resin or rubber layer containing a blend of at least two different polymers
- B32B 2307/304: Insulating
- B32B 2307/306: Resistant to heat
- B32B 2307/518: bi-axially
- B32B 2307/52: multi-axially
- B32B 2307/724: Permeability to gases, adsorption
- B32B 2307/732: Dimensional properties
- B32B 2457/10: Batteries
- C08J 2201/03: Extrusion of the foamable blend
- C08J 2201/0502: the liquid phase being organic
- C08J 2201/0543: the non-solvent being organic
- C08J 2205/02: the finished foam itself being a gel or a gel being temporarily formed when processing the foamable composition
- C08J 2323/06: Polyethene
- C08J 2427/16: Homopolymers or copolymers of vinylidene fluoride
- C08J 2427/20: Homopolymers or copolymers of hexafluoropropene
- Y02E 60/10: Energy storage using batteries
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A battery separator includes a polyolefin microporous membrane having a width of 100 mm or more, and a porous layer laminated on at least one surface of the polyolefin microporous membrane. The polyolefin microporous membrane has a variation range of an F25 value in a width direction of 1 MPa or less, and the F25 value indicates a value obtained by dividing a load value measured at 25% elongation of a specimen with use of a tensile tester by a cross-sectional area of the specimen. The porous layer contains a fluorine-based resin and an inorganic particle.

## Claims

### Claim 1

A battery separator comprising a polyolefin microporous membrane having a width of 100 mm or more, and a porous layer laminated on at least one surface of the polyolefin microporous membrane, wherein the polyolefin microporous membrane has a variation range of an F25 value in a width direction of 1 MPa or less (wherein the F25 value indicates a value obtained by dividing a load value measured at 25% elongation of a specimen with use of a tensile tester by a cross-sectional area of the specimen), and the porous layer contains a fluorine-based resin and an inorganic particle.

### Claim 2 (depends on 1)

The battery separator according to claim 1, wherein the porous layer has a thickness variation range (R) in a width direction of 1.0 μm or less.

### Claim 3 (depends on 2)

The battery separator according to claim 2, wherein the fluorine-based resin contains at least one member selected from a polyvinylidene fluoride and a polyvinylidene fluoride-hexafluoropropylene copolymer.

### Claim 4 (depends on 2)

The battery separator according to claim 2, wherein a width of the battery separator is 500 mm or more.

### Claim 5 (depends on 2)

A battery separator roll of the battery separator according to claim 2, wherein a length of the battery separator is 500 m or more.

### Claim 6 (depends on 1)

The battery separator according to claim 1, wherein the fluorine-based resin contains at least one member selected from a polyvinylidene fluoride and a polyvinylidene fluoride-hexafluoropropylene copolymer.

### Claim 7 (depends on 6)

The battery separator according to claim 6, wherein a width of the battery separator is 500 mm or more.

### Claim 8 (depends on 6)

A battery separator roll of the battery separator according to claim 6, wherein a length of the battery separator is 500 m or more.

### Claim 9 (depends on 1)

The battery separator according to claim 1, wherein a width of the battery separator is 500 mm or more.

### Claim 10 (depends on 9)

A battery separator roll of the battery separator according to claim 9, wherein a length of the battery separator is 500 m or more.

### Claim 11 (depends on 1)

A battery separator roll of the battery separator according to claim 1, wherein a length of the battery separator is 500 m or more.

### Claim 12 (depends on 1)

A method of producing the battery separator according to claim 1, the method comprising steps (a) to (g) in the following order:
(a) a step of melt-kneading a polyolefin resin and a forming solvent, thereby preparing a polyolefin resin solution;
(b) a step of extruding the polyolefin resin solution into a sheet shape via an extruder and cooling an extrudate thereof, thereby forming an unstretched gel-like sheet;
(c) a step of passing the unstretched gel-like sheet between at least two pairs of longitudinal stretching roller groups and stretching the sheet in a longitudinal direction based on a peripheral speed ratio of the two pairs of roller groups, thereby forming a longitudinally stretched gel-like sheet, wherein a longitudinal stretching roller and a nip roller parallelly contacting therewith are designated as a pair of longitudinal stretching roller group, and a contact pressure of the nip roller to the longitudinal stretching roller is 0.05 MPa or more and 0.5 MPa or less;
(d) a step of stretching the longitudinally stretched gel-like sheet in a transverse direction while holding the sheet to allow a clip-to-clip distance to be 50 mm or less at a tenter outlet, thereby obtaining a biaxially stretched gel-like sheet;
(e) a step of extracting the forming solvent from the biaxially stretched gel-like sheet and drying the sheet;
(f) a step of heat-treating the dried sheet, thereby obtaining a polyolefin microporous membrane; and
(g) a step of coating the polyolefin microporous membrane with a coating solution containing a fluorine-based resin and an inorganic particle by a reverse gravure coating method, passing the membrane through a coagulation bath, and then, subjecting to water washing and drying, thereby laminating a porous layer on the polyolefin microporous membrane.

### Claim 13 (depends on 12)

The method according to claim 12, wherein the coating solution has a solution viscosity of 50 to 200 mPa·s.

### Claim 14 (depends on 2)

A method of producing the battery separator according to claim 2, the method comprising steps (a) to (g) in the following order:
(a) a step of melt-kneading a polyolefin resin and a forming solvent, thereby preparing a polyolefin resin solution;
(b) a step of extruding the polyolefin resin solution into a sheet shape via an extruder and cooling an extrudate thereof, thereby forming an unstretched gel-like sheet;
(c) a step of passing the unstretched gel-like sheet between at least two pairs of longitudinal stretching roller groups and stretching the sheet in a longitudinal direction based on a peripheral speed ratio of the two pairs of roller groups, thereby forming a longitudinally stretched gel-like sheet, wherein a longitudinal stretching roller and a nip roller parallelly contacting therewith are designated as a pair of longitudinal stretching roller group, and a contact pressure of the nip roller to the longitudinal stretching roller is 0.05 MPa or more and 0.5 MPa or less;
(d) a step of stretching the longitudinally stretched gel-like sheet in a transverse direction while holding the sheet to allow a clip-to-clip distance to be 50 mm or less at a tenter outlet, thereby obtaining a biaxially stretched gel-like sheet;
(e) a step of extracting the forming solvent from the biaxially stretched gel-like sheet and drying the sheet;
(f) a step of heat-treating the dried sheet, thereby obtaining a polyolefin microporous membrane; and
(g) a step of coating the polyolefin microporous membrane with a coating solution containing a fluorine-based resin and an inorganic particle by a reverse gravure coating method, passing the membrane through a coagulation bath, and then, subjecting to water washing and drying, thereby laminating a porous layer on the polyolefin microporous membrane.

### Claim 15 (depends on 6)

A method of producing the battery separator according to claim 6, the method comprising steps (a) to (g) in the following order:
(a) a step of melt-kneading a polyolefin resin and a forming solvent, thereby preparing a polyolefin resin solution;
(b) a step of extruding the polyolefin resin solution into a sheet shape via an extruder and cooling an extrudate thereof, thereby forming an unstretched gel-like sheet;
(c) a step of passing the unstretched gel-like sheet between at least two pairs of longitudinal stretching roller groups and stretching the sheet in a longitudinal direction based on a peripheral speed ratio of the two pairs of roller groups, thereby forming a longitudinally stretched gel-like sheet, wherein a longitudinal stretching roller and a nip roller parallelly contacting therewith are designated as a pair of longitudinal stretching roller group, and a contact pressure of the nip roller to the longitudinal stretching roller is 0.05 MPa or more and 0.5 MPa or less;
(d) a step of stretching the longitudinally stretched gel-like sheet in a transverse direction while holding the sheet to allow a clip-to-clip distance to be 50 mm or less at a tenter outlet, thereby obtaining a biaxially stretched gel-like sheet;
(e) a step of extracting the forming solvent from the biaxially stretched gel-like sheet and drying the sheet;
(f) a step of heat-treating the dried sheet, thereby obtaining a polyolefin microporous membrane; and
(g) a step of coating the polyolefin microporous membrane with a coating solution containing a fluorine-based resin and an inorganic particle by a reverse gravure coating method, passing the membrane through a coagulation bath, and then, subjecting to water washing and drying, thereby laminating a porous layer on the polyolefin microporous membrane.

### Claim 16 (depends on 9)

A method of producing the battery separator according to claim 9, the method comprising steps (a) to (g) in the following order:
(a) a step of melt-kneading a polyolefin resin and a forming solvent, thereby preparing a polyolefin resin solution;
(b) a step of extruding the polyolefin resin solution into a sheet shape via an extruder and cooling an extrudate thereof, thereby forming an unstretched gel-like sheet;
(c) a step of passing the unstretched gel-like sheet between at least two pairs of longitudinal stretching roller groups and stretching the sheet in a longitudinal direction based on a peripheral speed ratio of the two pairs of roller groups, thereby forming a longitudinally stretched gel-like sheet, wherein a longitudinal stretching roller and a nip roller parallelly contacting therewith are designated as a pair of longitudinal stretching roller group, and a contact pressure of the nip roller to the longitudinal stretching roller is 0.05 MPa or more and 0.5 MPa or less;
(d) a step of stretching the longitudinally stretched gel-like sheet in a transverse direction while holding the sheet to allow a clip-to-clip distance to be 50 mm or less at a tenter outlet, thereby obtaining a biaxially stretched gel-like sheet;
(e) a step of extracting the forming solvent from the biaxially stretched gel-like sheet and drying the sheet;
(f) a step of heat-treating the dried sheet, thereby obtaining a polyolefin microporous membrane; and
(g) a step of coating the polyolefin microporous membrane with a coating solution containing a fluorine-based resin and an inorganic particle by a reverse gravure coating method, passing the membrane through a coagulation bath, and then, subjecting to water washing and drying, thereby laminating a porous layer on the polyolefin microporous membrane.