# US 12,183,946 B2 · Separator for power storage device

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- Number: US 12,183,946 B2
- Document ID: US12183946B2
- Status: Granted
- Kind: B2
- Application number: 17/442,202
- Filed: 2020-03-17
- Published: 2022-06-09
- Granted: 2024-12-31
- Earliest claimed: 2019-03-27
- Assignees: Asahi Kasei Kabushiki Kaisha
- Applicants: Asahi Kasei Kabushiki Kaisha
- Inventors: Masaki Takahashi; Tomoya Tagawa
- Web page: https://patentgrep.com/patent/US12183946B2

## CPC

- H01G 9/02: Diaphragms; Separators
- H01M 50/417: Polyolefins
- B32B 27/08: of synthetic resin
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- C08J 5/18: Manufacture of films or sheets
- H01G 11/52: Separators
- H01M 50/409: Separators, membranes or diaphragms characterised by the material
- H01M 50/449: having a layered structure
- 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
- B32B 2250/242: All polymers belonging to those covered by group B32B27/32
- B32B 2250/40: Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
- B32B 2274/00: Thermoplastic elastomer material
- B32B 2307/30: having particular thermal properties
- B32B 2307/5825: Tear resistant
- B32B 2307/72: Density
- B32B 2307/724: Permeability to gases, adsorption
- B32B 2307/732: Dimensional properties
- B32B 2457/10: Batteries
- Y02E 60/10: Energy storage using batteries
- H01G: CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE (selection of specified materials as dielectric H01B3/00; capacitors having potential barriers H10D1/62, H10K10/10)
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- 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)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

The purpose of the present invention is to provide a separator which is for a power storage device, and which has high strength and can be thinned. The separator for a power storage device has a microporous membrane containing polyolefin as a main component, wherein the melt tension of the microporous membrane as measured at a temperature of 230° C. is 30 mN or less, and the melt flow rate (MFR) of the microporous membrane as measured under a load of 2.16 kg and at a temperature of 230° C. is 0.9 g/10 min or less.

## Claims

### Claim 1

A separator for a power storage device, comprising a microporous membrane containing a polyolefin as a primary component, wherein
a melt tension of the microporous membrane measured at a temperature of 230° C. is 30 mN or less, and
a melt flow rate (MFR) of the microporous membrane measured under a load of 2.16 kg at a temperature of 230° C. is 0.9 g/10 min or less.

### Claim 2 (depends on 1)

The separator for a power storage device according to claim 1, wherein an area ratio (MD/TD) of (110) crystal peak as measured by wide-angle X-ray scattering of the microporous membrane containing a polyolefin as a primary component is 1.3 or more.

### Claim 3 (depends on 1)

The separator for a power storage device according to claim 1, wherein the polyolefin is polypropylene, and the MFR of the polypropylene measured under a load of 2.16 kg at a temperature of 230° C. is 0.3 to 0.9 g/10 min.

### Claim 4 (depends on 3)

The separator for a power storage device according to claim 3, wherein a pentad fraction of the polypropylene as measured by 13C-NMR (nuclear magnetic resonance) is 95.0% or more.

### Claim 5 (depends on 4)

The separator for a power storage device according to claim 4, wherein the pentad fraction of the polypropylene is 97.0% or more.

### Claim 6 (depends on 1)

The separator for a power storage device according to claim 1, wherein the melt tension of the microporous membrane is 20 mN to 30 mN.

### Claim 7 (depends on 1)

The separator for a power storage device according to claim 1, wherein a value (Mw/Mn) obtained by diving the weight average molecular weight (Mw) of the polypropylene by the number average molecular weight (Mn) thereof is 7 or less.

### Claim 8 (depends on 1)

The separator for a power storage device according to claim 1, wherein the polyolefin is polypropylene, the microporous membrane further comprises an elastomer, and the MFR of the polypropylene measured under a load of 2.16 kg at a temperature of 230° C. is 0.6 g/10 min or less.

### Claim 9 (depends on 8)

The separator for a power storage device according to claim 8, wherein the elastomer has a propylene structure as a repeating unit.

### Claim 10 (depends on 8)

The separator for a power storage device according to claim 8, wherein the pentad fraction of the polypropylene as measured by 13C-NMR (nuclear magnetic resonance) is 95.0% or more.

### Claim 11 (depends on 1)

The separator for a power storage device according to claim 1, wherein the separator for a power storage device has a multilayer structure comprising the microporous membrane and a microporous membrane containing polyethylene as a primary component.

### Claim 12 (depends on 11)

The separator for a power storage device according to claim 11, wherein a thickness of the multilayer structure is 18 μm or less, and the separator for a power storage device has an air permeability of 300 s/100 cc·14 μm or less, and a puncture strength of 300 gf/14 μm or more, which are calculated by converting the thickness into 14 μm.

### Claim 13 (depends on 1)

A power storage device, comprising a positive electrode, a negative electrode, and the separator for a power storage device according to claim 1 laminated between the positive electrode and the negative electrode.