# US 10,483,049 B2 · Lithium ion capacitor

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- Number: US 10,483,049 B2
- Document ID: US10483049B2
- Status: Granted
- Kind: B2
- Application number: 15/474,399
- Filed: 2017-03-30
- Published: 2017-11-30
- Granted: 2019-11-19
- Earliest claimed: 2016-05-30
- Assignees: Taiyo Yuden Co., Ltd.
- Applicants: Taiyo Yuden Co., Ltd.
- Inventors: Takeo Tsuzuki
- Web page: https://patentgrep.com/patent/US10483049B2

## CPC

- H01G 11/60: characterised by the solvent
- H01G 11/52: Separators
- H01G 11/62: characterised by the solute, e.g. salts, anions or cations therein
- H01G 11/64: characterised by additives
- H01G 11/74: Terminals, e.g. extensions of current collectors
- H01G 11/80: Gaskets; Sealings
- Y02E 60/13: Energy storage using capacitors
- 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 lithium ion capacitor has an electrolytic solution that contains: an electrolyte which is a mixture of LiFSI and LiBF4, where the mol ratio of LiFSI to LiBF4 is in a range of 90/10 to 30/70; a solvent that contains at least one type of cyclic or chained carbonate compound; and a film-forming agent; wherein the concentration of electrolyte in the electrolytic solution is in a range of 1.2 to 1.8 mol/L. The lithium ion capacitor can maintain its initial high capacitance and low internal resistance, while also undergoing minimal characteristics changes after exposure to a high-temperature, high-voltage environment.

## Claims

### Claim 1

A lithium ion capacitor having an electrolytic solution that contains:
an electrolyte which is a mixture of LiFSI and LiBF4 which are the only lithium salts used as the electrolyte, where the mol ratio of LiFSI to LiBF4 is in a range of 90/10 to 30/70;
a solvent that contains at least one cyclic or chained carbonate compound; and
a film-forming agent which suppresses reductive decomposition of the solvent by reductively decomposing itself at a potential higher than that of the solvent, thereby forming a film on a negative electrode;
wherein a concentration of electrolyte in the electrolytic solution is in a range of 1.2 to 1.8 mol/L.

### Claim 2 (depends on 1)

A lithium ion capacitor according to claim 1, wherein the film-forming agent contains at least one of vinylene carbonate and fluoroethylene carbonate.

### Claim 3 (depends on 1)

A lithium ion capacitor according to claim 1, wherein a concentration of the film-forming agent in the electrolytic solution is in a range of 0.5 to 2.0 percent by weight.

### Claim 4 (depends on 2)

A lithium ion capacitor according to claim 2, wherein a concentration of the film-forming agent in the electrolytic solution is in a range of 0.5 to 2.0 percent by weight.