# US 12,119,513 B2 · Separator for lithium-ion secondary battery

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,119,513 B2
- Document ID: US12119513B2
- Status: Granted
- Kind: B2
- Application number: 16/491,251
- Filed: 2018-04-03
- Published: 2020-01-30
- Granted: 2024-10-15
- Earliest claimed: 2017-04-06
- Assignees: Asahi Kasei Kabushiki Kaisha; Celgard, LLC
- Applicants: Asahi Kasei Kabushiki Kaisha; Celgard, LLC
- Inventors: Takahiko Kondo; Kazunori Uchida; Shinya Hamasaki
- Web page: https://patentgrep.com/patent/US12119513B2

## CPC

- B29D 7/01: Films or sheets
- H01M 50/44: Fibrous material
- B29C 55/005: {characterised by the choice of materials}
- B29C 55/04: uniaxial, e.g. oblique
- B29C 55/12: biaxial
- B29C 55/143: {firstly parallel to the direction of feed and then transversely thereto}
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 10/4235: {Safety or regulating additives or arrangements in electrodes, separators or electrolyte (H01M10/4242 takes precedence)}
- H01M 50/417: Polyolefins
- H01M 50/457: comprising three or more layers
- 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
- H01M 50/491: Porosity
- B29K 2023/12: {PP, i.e. polypropylene}
- B29K 2105/041: {Microporous}
- B29L 2031/3468: {Batteries, accumulators or fuel cells (battery cases B29L2031/7146)}
- H01M 50/403: Manufacturing processes of separators, membranes or diaphragms
- H01M 50/406: Moulding; Embossing; Cutting
- Y02E 60/10: Energy storage using batteries
- B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00)
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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)
- 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

Problem: The invention provides a separator for a lithium-ion secondary battery exhibiting excellent strength, wettability with nonaqueous electrolyte solutions, voltage endurance and cycle characteristics in lithium-ion secondary batteries, and a method of increasing the puncture depth of the separator. Solution: A separator for a lithium-ion secondary battery is formed of a microporous film comprising a polyolefin resin (A) as a major component, and a resin (B), at least portions of the surfaces of the micropores in the microporous film being coated with resin (B).

## Claims

### Claim 1

A separator for a lithium-ion secondary battery, comprising a microporous film, wherein the microporous film comprises:
a polyolefin resin (A) comprising polypropylene as a major component; and
interior surfaces of micropores in the microporous film are coated with a resin (B) different from the polyolefin resin (A), and a coated amount of the resin (B) is 5 to 70 weight % based on the total resin weight,
wherein the resin (B) is a C3 unit-containing polyolefin copolymer, or a polyolefin with an elastic modulus of 110 to 520 MPa at 25° C. and a melting point of no higher than 130° C.;
wherein the separator has a porosity of 41% to 58%, and an air permeability of 161 sec/100 cc to 244 sec/100 cc, and
wherein the separator is free of a fluorine-containing resin binder.

### Claim 2 (depends on 1)

The separator according to claim 1, wherein the micropores are formed with fibrils of the polyolefin resin (A), and outer surfaces of the fibrils are surrounded by the resin (B).

### Claim 3 (depends on 1)

The separator according to claim 1, wherein, in an intermediate layer selected among three layers obtained by trisecting the separator in the film thickness direction, at least one part of a surface layer of a skeleton consisting of the polyolefin resin (A) is coated with the resin (B).

### Claim 4 (depends on 1)

The separator according to claim 1, wherein the separator has a puncture depth of 2.5 mm or more.

### Claim 5 (depends on 4)

The separator according to claim 4, wherein the puncture depth is more than 2.5 mm and equal to or less than 4.5 mm.

### Claim 6 (depends on 1)

The separator according to claim 1, wherein the resin (B) has an elastic modulus at 25 degrees Celsius of 110 to 520 MPa.

### Claim 7 (depends on 6)

The separator according to claim 6, wherein the elastic modulus at 25 degrees Celsius is 110 to 520 MPa.

### Claim 8 (depends on 1)

The separator according to claim 1, wherein the resin (B) is a hydrophobic resin.

### Claim 9 (depends on 8)

The separator according to claim 8, wherein the hydrophobic resin has a solubility in octane at 25 degrees Celsius of 20 g/kg or more.

### Claim 10 (depends on 8)

The separator according to claim 8, wherein the hydrophobic resin is a polyolefin resin having an elastic modulus at 25 degrees Celsius of 110 to 520 MPa.

### Claim 11 (depends on 1)

The separator according to claim 1, wherein the separator has a puncture strength of 0.25 kgf or more.

### Claim 12 (depends on 1)

The separator according to claim 1, wherein the membrane thickness of the separator is equal to or less than 100 μm.

### Claim 13 (depends on 1)

The separator according to claim 1, wherein a fuse temperature of the separator is less than 150 degrees Celsius.

### Claim 14 (depends on 1)

The separator according to claim 1, wherein the microporous film is obtainable by stretching a precursor comprising the polyolefin resin (A), and subsequently impregnating the stretched product with the resin (B).

### Claim 15 (depends on 14)

The separator according to claim 14, wherein the microporous film is obtainable by stretching the precursor in at least a transverse direction (TD), and subsequently impregnating the TD-stretched product with the resin (B).

### Claim 16 (depends on 15)

The separator according to claim 15, wherein the microporous film is obtainable by stretching the precursor in at least the transverse direction (TD), calendering the TD-stretched product, and subsequently impregnating the calendered product with the resin (B).

### Claim 17 (depends on 15)

The separator according to claim 15, wherein the microporous film is obtainable by stretching the precursor in at least the transverse direction (TD), impregnating the TD-stretched product with the resin (B), and subsequently calendering the impregnated product.

### Claim 18 (depends on 14)

The separator according to claim 14, wherein the microporous film is obtainable by stretching the precursor in at least a machine direction (MD), and subsequently impregnating the MD-stretched product with the resin (B).