# US 12,763,372 B2 · Chemical additives for liquefied gas electrolytes

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- Number: US 12,763,372 B2
- Document ID: US12763372B2
- Status: Granted
- Kind: B2
- Application number: 19/220,824
- Filed: 2025-05-28
- Published: 2025-12-04
- Granted: 2026-10-13
- Earliest claimed: 2024-05-28
- Assignees: South 8 Technologies, Inc.
- Applicants: South 8 Technologies, Inc.
- Inventors: Frederick Krause; Jeremy Intrator; Cyrus S Rustomji
- Web page: https://patentgrep.com/patent/US12763372B2

## CPC

- H01M 10/0569: characterised by the solvents
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY

## Abstract

An electrochemical device is disclosed that includes an ionically conducting electrolyte, a first electrode and a second electrode. The electrodes are in contact with the ionically conducting electrolyte, and a housing encloses the electrodes and the ionically conducting electrolyte. The ionically conducting electrolyte comprises a liquefied gas solvent, an ester solvent, and a salt. The liquefied gas solvent has a vapor pressure above 100 kPa at a temperature of 293.15K. The salt and ester are soluble in the liquefied gas solvent such that the ionically conducting electrolyte is a liquid under pressure.

## Claims

### Claim 1

An electrochemical device, comprising:
an ionically conducting electrolyte comprising a liquefied gas solvent, an organic liquid ester, and a salt, wherein:
the liquefied gas solvent has a vapor pressure above 100 kPa at a temperature of 293.15K;
the salt is soluble in the liquefied gas solvent; and
the organic liquid ester is soluble in the liquefied gas solvent such that the ionically conducting electrolyte is a liquid under pressure;
a first electrode and a second electrode in contact with the ionically conducting electrolyte;
a housing that encloses the ionically conducting electrolyte, the first electrode and the second electrode, and maintains the electrolyte under sufficient pressure to keep the liquefied gas solvent in a liquid state at room temperature during normal operation, wherein the housing is a sealed cell housing that does not include a gas inlet or a gas outlet configured for continuous purging of gaseous reactants during normal operation of the electrochemical device; and
wherein the liquid organic ester is configured to increase the solubility of the salt in the electrolyte, to decrease the viscosity of the electrolyte, to improve the ionic conductivity of the electrolyte, and to participate in the formation of a stable solid electrolyte interphase film on a surface of at least one of the first electrode or the second electrode.

### Claim 2 (depends on 1)

The electrochemical device of claim 1, wherein the molar concentration of the salt in the ionically conducting electrolyte ranges from about 0.01 to about 25 M.

### Claim 3 (depends on 1)

The electrochemical device of claim 1, wherein the salt is selected from a group consisting of: LiTFSI, LiFSI, LiPF6, LiBOB, LiBF4, LiDFOB, LiNO3, and combinations thereof.

### Claim 4 (depends on 1)

The electrochemical device of claim 1, wherein the liquefied gas solvent is selected from a group consisting of: dimethyl ether, methyl ethyl ether, fluoromethane, difluoromethane, trifluoromethane, fluoroethane, tetrafluoroethane, pentafluoroethane, 1,1-difluoroethane, 1,2-difluoroethane, 1,1,1-trifluoroethane, 1,1,2-trifluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,2,2-tetrafluoroethane, pentafluoroethane, chloromethane, chloroethane, thionyl fluoride, thionyl chloride fluoride, phosphoryl fluoride, phosphoryl chloride fluoride, sulfuryl fluoride, sulfuryl chloride fluoride, 1-fluoropropane, 2-fluoropropane, 1,1-difluoropropane, 1,2-difluoropropane, 2,2-fluoropropane, 1,1,1-trifluoropropane, 1,1,2-trifluoropropane, 1,2,2-trifluoropropane, fluoroethylene, cis-1,2-fluoroethylene, 1,1-fluoroethylene, 1-fluoropropylene, 2-propylene, chlorine, chloromethane, bromine, iodine, ammonia, methyl amine, dimethyl amine, trimethyl amine, molecular oxygen, molecular nitrogen, carbon monoxide, carbon dioxide, sulfur dioxide, methyl vinyl ether, difluoro ethylene, nitrous oxide, nitrogen dioxide, nitrogen oxide, carbon disulfide, hydrogen fluoride, hydrogen chloride and combinations thereof.

### Claim 5 (depends on 1)

The electrochemical device of claim 1, wherein the organic liquid ester is selected from a group consisting of: methyl formate, methyl acetate, methyl propionate, methyl butyrate, ethyl formate, ethyl acetate, ethyl propionate, ethyl butyrate, propyl formate, propyl acetate, propyl propionate, propyl butyrate, trifluoromethyl formate, trifluoromethyl fluoroformate, 2,2,2-trifluoroethyl formate, 2,2,2-trifluoroethyl acetate, ethyl trifluoroacetate, 2,2,2-trifluoroethyl trifluoroacetate, 2,2,2-trifluoroethyl butyrate, acetolactone, α-propiolactone, α-butyrolactone, α-valerolactone, α-caprolactone, α-heptalactone, α-octalactone, β-propiolactone, β-butyrolactone, β-valerolactone, β-caprolactone, β-heptalactone, β-octalactone, γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-heptalactone, γ-octalactone, δ-valerolactone, δ-caprolactone, δ-heptalactone, δ-octalactone, ε-caprolactone, ε-heptalactone, ε-octalactone, and combinations thereof.

### Claim 6 (depends on 1)

The electrochemical device of claim 1, wherein the first electrode and the second electrode are selected from a group consisting of: graphite, carbon, activated carbon, vanadium oxide, lithium titanate, titanium disulfide, molybdenum disulfide, lithium iron phosphate, lithium cobalt phosphate, lithium nickel phosphate, lithium cobalt oxide, lithium nickel manganese oxide, lithium nickel manganese cobalt oxide, and lithium nickel cobalt aluminum oxide.

### Claim 7 (depends on 1)

The electrochemical device of claim 1, wherein the first electrode is selected from a group consisting of: lithium metal, sodium metal, calcium metal, magnesium metal, aluminum metal, zinc metal, and combinations thereof.

### Claim 8 (depends on 1)

The electrochemical device of claim 1, wherein the ionically conducting electrolyte further comprises an additive selected from a group consisting of: a non-cyclic carbonate, cyclic carbonate, ether, cyclic-ether, nitrile, an organophosphate, and combinations thereof.

### Claim 9 (depends on 1)

The electrochemical device of claim 1, wherein the electrochemical device is a battery or a capacitor.

### Claim 10 (depends on 1)

The electrochemical device of claim 1, wherein the SEI comprises lithium acetate that is formed by reductive decomposition of the organic liquid ester during cell formation or initial charging and is non-soluble in the liquefied gas solvent.