# US 2021/0280945 A1 · Separator for electrochemical device and method for manufacturing the same

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- Number: US 2021/0280945 A1
- Document ID: US20210280945A1
- Status: Published application
- Kind: A1
- Application number: 17/255,825
- Filed: 2019-09-27
- Published: 2021-09-09
- Earliest claimed: 2018-09-28
- Assignees: LG Chem, Ltd.
- Applicants: LG Chem, Ltd.
- Inventors: Young-Bok KIM; Dong-Wook SUNG; So-Mi JEONG
- Web page: https://patentgrep.com/patent/US20210280945A1

## CPC

- H01M 50/449: having a layered structure
- H01G 11/52: Separators
- 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 50/417: Polyolefins
- H01M 50/42: Acrylic resins
- H01M 50/426: Fluorocarbon polymers
- H01M 50/431: Inorganic material
- H01M 50/443: Particulate material
- 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 50/461: {with adhesive layers between electrodes and separators}
- 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
- Y02E 60/10: Energy storage using batteries
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A separator including a porous polymer substrate and an inorganic coating layer formed on at least one surface of the porous polymer substrate. The inorganic coating layer includes inorganic particles and a binder resin. The binder resin includes a first binder resin and a second binder resin. The first binder resin comprises a polyvinylidene fluoride (PVdF)-based polymer and the second binder resin comprises an acrylic polymer. The acrylic polymer has an acid value of 1 or less and a glass transition temperature, Tg, of 90° C. to 130° C. In addition, the inorganic coating layer has a high content of binder resin at the top layer portion to provide excellent adhesion between the separator and an electrode.

## Claims

### Claim 1

A separator for an electrochemical device which comprises:
a porous polymer substrate, and
an inorganic coating layer formed on at least one surface of the porous polymer substrate,
wherein the inorganic coating layer comprises inorganic particles and a binder resin,
wherein the binder resin comprises a first binder resin and a second binder resin,
wherein the first binder resin comprises a polyvinylidene fluoride (PVdF)-based polymer and the second binder resin comprises an acrylic polymer, and
wherein the acrylic polymer has an acid value of 1 or less and a glass transition temperature, Tg, of 90° C. to 130° C.

### Claim 2 (depends on 1)

The separator for an electrochemical device according to claim 1, wherein the acrylic polymer has a weight average molecular weight (Mw) of 100,000 to 200,000.

### Claim 3 (depends on 1)

The separator for an electrochemical device according to claim 1, wherein the acrylic polymer comprises a (meth)acrylate-containing (meth)acrylic polymer, and
wherein monomer of the (meth)acrylate polymer comprises at least one selected from the group consisting of butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate and tetradecyl (meth)acrylate.

### Claim 4 (depends on 1)

The separator for an electrochemical device according to claim 1, wherein the acrylic polymer comprises poly(methyl methacrylate) (PMMA).

### Claim 5 (depends on 1)

The separator for an electrochemical device according to claim 1, wherein the acrylic polymer comprises poly(methyl methacrylate) (PMMA), and
wherein the PMMA has a molecular average molecular weight (Mw) of 100,000 to 200,000, an acid value of 1 or less, and a glass transition temperature, Tg, of 90° C. to 130° C.

### Claim 6 (depends on 1)

The separator for an electrochemical device according to claim 1, wherein the acrylic polymer is present in an amount of 10 wt % to 80 wt % based on 100 wt % of the binder resin.

### Claim 7 (depends on 1)

The separator for an electrochemical device according to claim 1, wherein the acrylic polymer is present in an amount of 10 wt % to 50 wt % based on 100 wt % of the binder resin.

### Claim 8 (depends on 1)

The separator for an electrochemical device according to claim 1, wherein the PVdF-based polymer comprises at least one of vinylidene fluoride homopolymer, or copolymer of vinylidene fluoride with a copolymerizable monomer.

### Claim 9 (depends on 8)

The separator for an electrochemical device according to claim 8, wherein the PVdF-based polymer has a molecular weight (Mw) of 300,000 to 1,000,000.

### Claim 10 (depends on 8)

The separator for an electrochemical device according to claim 8, wherein the monomer copolymerizable with vinylidene fluoride is at least one selected from the group consisting of vinyl fluoride, trifluoroethylene (TrFE), chlorotrifluoroethylene (CTFE), 1,2-difluoroethylene, tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoro(alkylvinyl)ether, perfluoro(1,3-dioxole) and perfluoro(2,2-dimethyl-1,3-dioxole) (PDD).

### Claim 11 (depends on 1)

The separator for an electrochemical device according to claim 1, wherein a portion of the inorganic coating layer at a surface of the inorganic coating layer opposite to the porous polymer substrate forms an electrode adhesive portion, wherein the electrode adhesive portion has a content of binder resin that is higher than a content of binder resin in the remainder of the inorganic coating layer adjacent to the porous polymer substrate.

### Claim 12 (depends on 11)

The separator for an electrochemical device according to claim 11, wherein the electrode adhesive portion is disposed on the surface of the inorganic coating layer of the separator through a phase separation process under a humidified condition.

### Claim 13 (depends on 12)

The separator for an electrochemical device according to claim 12, wherein the humidified condition comprises a relative humidity of 40% to 80%.

### Claim 14 (depends on 1)

An electrode assembly for an electrochemical device comprising:
a positive electrode a negative electrode; and
a separator interposed between the positive electrode and the negative electrode,
wherein the separator is as defined in claim 1.

### Claim 15 (depends on 1)

A method for manufacturing the separator for an electrochemical device as defined in claim 1, the method comprising:
preparing the porous polymer substrate;
applying a slurry for the inorganic coating layer onto at least one surface of the porous polymer substrate;
subjecting the slurry to phase separation under a humidified condition to form an electrode adhesive portion of the inorganic coating layer on the surface of the inorganic coating layer of the separator, wherein a content of binder resin is higher in the electrode adhesive portion than a content of binder resin in the remainder of the inorganic coating layer adjacent to the porous polymer substrate.

### Claim 16 (depends on 15)

The method for manufacturing the separator for an electrochemical device according to claim 15, wherein the humidified condition comprises a relative humidity of 40% to 80%.

### Claim 17 (depends on 11)

The separator for an electrochemical device according to claim 11, wherein the electrode adhesive portion is integral and indivisible from the remainder of the inorganic coating layer adjacent to the porous polymer substrate, and wherein the electrode adhesive portion comprises the binder resin in an amount of 70 wt % or more from a topmost portion in a thickness direction of the inorganic coating layer.