# US 11,309,579 B2 · Lithium ion secondary battery and method for producing the same

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- Number: US 11,309,579 B2
- Document ID: US11309579B2
- Status: Granted
- Kind: B2
- Application number: 16/813,101
- Filed: 2020-03-09
- Published: 2020-09-17
- Granted: 2022-04-19
- Earliest claimed: 2019-03-12
- Assignees: Toyota Jidosha Kabushiki Kaisha
- Applicants: Toyota Jidosha Kabushiki Kaisha
- Inventors: Rune Onishi; Ryo Suzuki; Hideaki Oka
- Web page: https://patentgrep.com/patent/US11309579B2

## CPC

- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 4/133: Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 4/134: Electrodes based on metals, Si or alloys
- H01M 4/1393: of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 4/1395: of electrodes based on metals, Si or alloys
- H01M 4/382: {Lithium (H01M4/405 takes precedence)}
- H01M 4/405: {Alloys based on lithium}
- H01M 4/587: for inserting or intercalating light metals
- H01M 4/663: {containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres}
- H01M 2004/021: {Physical characteristics, e.g. porosity, surface area}
- Y02E 60/10: Energy storage using batteries
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- 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
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

Provided is a lithium ion secondary battery with enhanced charge-discharge characteristics. Disclosed is a lithium ion secondary battery comprising: a columnar anode comprising a carbon fiber assembly having an assembled carbon fiber structure, a cathode, and an ion-conducting, insulating separation film disposed between the cathode and the anode to insulate the cathode and the anode from each other, wherein a void content of the carbon fiber assembly is 20% or more and 40% or less, and wherein at least one of a lithium metal and a lithium alloy is contained in voids of the carbon fiber assembly, when the lithium ion secondary battery is in a fully charged state.

## Claims

### Claim 1

A lithium ion secondary battery comprising:
a columnar anode comprising a carbon fiber assembly having an assembled carbon fiber structure,
a cathode, and
an ion-conducting, insulating separation film disposed between the cathode and the anode to insulate the cathode and the anode from each other,
wherein a void content of the carbon fiber assembly is 20% or more and 40% or less, and
wherein at least one of a lithium metal and a lithium alloy is contained in voids of the carbon fiber assembly, when the lithium ion secondary battery is in a fully charged state.

### Claim 2 (depends on 1)

The lithium ion secondary battery according to claim 1, wherein a ratio of a capacity of the anode to a capacity of the cathode (anode capacity/cathode capacity) is smaller than 1.

### Claim 3 (depends on 1)

The lithium ion secondary battery according to claim 1, wherein a metal to be alloyed with the lithium contained in the lithium alloy, is at least one kind of metal selected from the group consisting of gold, platinum, magnesium, zinc, tungsten, molybdenum, aluminum, gallium, indium, silicon, germanium, tin, lead, arsenic, antimony and bismuth.

### Claim 4 (depends on 1)

The lithium ion secondary battery according to claim 1, wherein the anode is a polygonal columnar anode that a length of a side of a cross section in a direction perpendicular to a longitudinal direction, is 30 μm or more and 1000 μm or less, or a round columnar anode with a diameter of 30 μm or more and 1000 μm or less, and wherein an outer circumferential surface other than end surfaces in the longitudinal direction faces the cathode through the separation film.

### Claim 5 (depends on 1)

A method for producing the lithium ion secondary battery defined by claim 1, the method comprising:
loading the metal to be alloyed with the lithium or a compound of the metal on the surface of the carbon fibers by passing the carbon fibers through a first nozzle that is filled with a liquid containing the metal or the compound of the metal, and
obtaining the carbon fiber assembly by assembling the metal-loading carbon fibers and passing the assembled carbon fibers through a second nozzle that is filled with a binder solution containing a binder.