# US 2021/0242534 A1 · Functional separator, manufacturing method therefor, and lithium secondary battery comprising same

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- Number: US 2021/0242534 A1
- Document ID: US20210242534A1
- Status: Published application
- Kind: A1
- Application number: 17/052,918
- Filed: 2019-10-25
- Published: 2021-08-05
- Earliest claimed: 2018-10-26
- Assignees: LG Chem, Ltd.
- Applicants: LG Chem, Ltd.
- Inventors: Kihyun KIM; Seungbo YANG; Jangsoo LEE
- Web page: https://patentgrep.com/patent/US20210242534A1

## CPC

- H01M 10/4235: {Safety or regulating additives or arrangements in electrodes, separators or electrolyte (H01M10/4242 takes precedence)}
- H01M 50/431: Inorganic material
- 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 50/443: Particulate material
- H01M 50/449: having a layered structure
- H01M 50/457: comprising three or more layers
- H01M 10/052: Li-accumulators
- Y02E 60/10: Energy storage using batteries
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A functional separator capable of improving the capacity and lifetime of a battery by coating a material capable of reducing lithium polysulfide on a separator surface in order to resolve the problems caused by leaching of lithium polysulfide, a preparation method thereof and a lithium secondary battery including the same. The functional separator includes a base separator; a conductive carbon layer on the surface of the base separator; and a metal oxide formed on at least one of an interior and the surface of the conductive carbon layer.

## Claims

### Claim 1

A functional separator comprising:
a base separator;
a conductive carbon layer on a surface of the base separator; and
a metal oxide on at least one of the interior and the surface of the conductive carbon layer.

### Claim 2 (depends on 1)

The functional separator according to claim 1, wherein a total weight of the conductive carbon layer and the metal oxide is 0.1 parts by weight to 40 parts by weight relative to 100 parts by weight of the base separator.

### Claim 3 (depends on 1)

The functional separator according to claim 1, wherein no binder is present between the conductive carbon layer and the base separator.

### Claim 4 (depends on 1)

The functional separator according to claim 1, wherein the conductive carbon of the conductive carbon layer is selected from the group consisting of carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, thermally-expanded reduced graphene oxide and graphite oxide.

### Claim 5 (depends on 4)

The functional separator according to claim 4, wherein the conductive carbon is thermally-expanded reduced graphene oxide.

### Claim 6 (depends on 1)

The functional separator according to claim 1, wherein a content of the conductive carbon layer is 0.05 parts by weight to 20 parts by weight relative to 100 parts by weight of a total weight of the base separator.

### Claim 7 (depends on 1)

The functional separator according to claim 1, wherein the metal oxide comprises an inorganic metal selected from the group consisting of manganese, magnesium, aluminum, cerium, iron, cobalt, vanadium, titanium, zinc, molybdenum and chromium.

### Claim 8 (depends on 1)

The functional separator according to claim 1, wherein the metal oxide is manganese oxide selected from the group consisting of manganese monoxide (MnO), manganese dioxide (MnO2), manganese trioxide (MnO3), trimanganese tetraoxide (Mn3O4) and dimanganese trioxide (Mn2O3).

### Claim 9 (depends on 1)

The functional separator according to claim 1, wherein a content of the metal oxide is 1 parts by weight to 1,000 parts by weight relative to 100 parts by weight of a total weight of the conductive carbon layer.

### Claim 10

A method for preparing a functional separator comprising the steps of:
(a) mixing and reacting a conductive carbon and a metal oxide precursor in the presence of a solvent to prepare a carbon-metal oxide mixture; and
(b) coating the prepared carbon-metal oxide mixture on a surface of a base separator.

### Claim 11 (depends on 10)

The method for preparing the functional separator according to claim 10, wherein the carbon-metal oxide mixture is coated on the base separator without a binder.

### Claim 12 (depends on 1)

A lithium secondary battery comprising: a positive electrode; a negative electrode; the functional separator of claim 1 interposed between the positive electrode and the negative electrode; and an electrolyte.

### Claim 13 (depends on 12)

The lithium secondary battery according to claim 12, wherein the lithium secondary battery is a lithium-sulfur battery.

### Claim 14 (depends on 1)

The functional separator according to claim 1, wherein the conductive carbon layer is present on a part of the surface of the base separator.

### Claim 15 (depends on 1)

The functional separator according to claim 1, wherein the conductive carbon layer is present on an entirety of the surface of the base separator.