# US 12,770,923 B2 · Electrolyte solution for lithium secondary battery and lithium secondary battery including the same

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- Number: US 12,770,923 B2
- Document ID: US12770923B2
- Status: Granted
- Kind: B2
- Application number: 18/094,762
- Filed: 2023-01-09
- Published: 2023-07-20
- Granted: 2026-10-20
- Earliest claimed: 2022-01-14
- Assignees: SK On Co., Ltd.
- Applicants: SK On Co., Ltd.; SK Innovation Co., Ltd.
- Inventors: In Haeng Cho; Yu Na Shim; Moon Sung Kim; Sung Jin Kim; Soo Min Park; Min Young Lee; Jin Hong Lee
- Web page: https://patentgrep.com/patent/US12770923B2

## CPC

- H01M 10/0567: characterised by the additives
- C07F 9/06: without P—C bonds
- H01M 10/052: Li-accumulators
- H01M 10/0569: characterised by the solvents
- H01M 10/0585: of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
- H01M 2300/004: Three solvents
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- C07F: ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM (metal-containing porphyrins C07D487/22)

## Abstract

An electrolyte solution for a lithium secondary battery includes an organic solvent, a lithium salt, and a fluorine-based additive in which a terminal difluoro-phosphite group (—OPF2) is bonded to a branched saturated hydrocarbon group. The fluorine-based additive prevent side reactions in the electrolyte solution to improve stability of a cathode active material.

## Claims

### Claim 1

An electrolyte solution for a lithium secondary battery, comprising:
an organic solvent;
a lithium salt; and
a fluorine-based additive in which a terminal difluoro-phosphite group (—OPF2) is bonded to a branched saturated hydrocarbon group,
wherein the fluorine-based additive comprises a compound represented by Chemical Formula 2 below:
wherein, in Chemical Formula 2, R3 and R4 are each independently a C1-C10 alkyl group.

### Claim 2 (depends on 1)

The electrolyte solution for a lithium secondary battery according to claim 1, wherein R3 and R4 are each independently a C1-C3 alkyl group.

### Claim 3 (depends on 1)

The electrolyte solution for a lithium secondary battery according to claim 1, wherein the fluorine-based additive comprises a compound represented by Chemical Formula 2-1:

### Claim 4 (depends on 1)

The electrolyte solution for a lithium secondary battery according to claim 1, wherein the fluorine-based additive is included in an amount ranging from 0.1 wt % to 5.0 wt % based on a total weight of the electrolyte solution.

### Claim 5 (depends on 1)

The electrolyte solution for a lithium secondary battery according to claim 1, wherein the fluorine-based additive is included in an amount ranging from 0.5 wt % to 2.0 wt % based on a total weight of the electrolyte solution.

### Claim 6 (depends on 1)

The electrolyte solution for a lithium secondary battery according to claim 1, further comprising at least one auxiliary additive selected from the group consisting of a cyclic carbonate-based compound, a fluorine-substituted cyclic carbonate-based compounds, a sultone-based compound and a cyclic sulfate-based compound.

### Claim 7 (depends on 6)

The electrolyte solution for a lithium secondary battery according to claim 6, wherein the auxiliary additive is included in an amount ranging from 0.01 wt % to 5 wt % based on a total weight of the electrolyte solution.

### Claim 8 (depends on 1)

The electrolyte for a lithium secondary battery according to claim 1, wherein the organic solvent includes at least one selected from the group consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC) and diethyl carbonate (DEC).

### Claim 9 (depends on 1)

A lithium secondary battery, comprising:
an electrode assembly comprising a plurality of cathodes and anodes that are repeatedly stacked;
a case accommodating the electrode assembly; and
the electrolyte solution for a lithium secondary battery of claim 1 accommodated in the case together with the electrode assembly.