Electrolytes including fluorinated solvents for use in electrochemical cells
First Claim
1. An electrolyte for use in an electrochemical cell, the electrolyte comprising:
- an electrolyte salt comprising at least one carbon atom and at least two fluoride atoms and is selected from the group consisting of;
i) fluoroalkyl-substituted LiPF6 salts having a general structure LiPFxR1-x, wherein x is from 1 to 5 and wherein at least one R is a fluorinated alkyl having a chain length of from 1 to 8;
ii) fluoroalkyl-substituted LiBF4 salts having a general structure LiBFxR1-x, wherein x is from 1 to 4 and wherein at least one R is a fluorinated alkyl having a chain length of from 1 to 8;
iii) linear imide salts having a general structure LiN(—
SO2—
R)2, wherein at least one R is a fluorinated alkyl having a chain length of from 1 to 8;
iv) cyclic imide salts having a general structure LiN(—
SO2—
R—
), wherein R is fluorinated alkyl having a chain length of from 1 to 8; and
v) methide salts having a general structure LiC(—
SO2—
R)3, wherein at least one R is fluorinated alkyl with a chain length of from 1 to 8;
a fluorinated solvent being present at a concentration of between about 30% and 80% by weight excluding a weight of the electrolyte salt, wherein the fluorinated solvent has a general structure CxFyHzOi such that x is an integer ranging from 3 to 15, y is an integer ranging from 1 to 30, z is an integer ranging from 0 to 15, and i is an integer ranging from 1 to 5; and
a non-fluorinated solvent selected from the group consisting of an ester, an ether, and a carbonate wherein a weight ratio of the non-fluorinated solvents to the fluorinated solvent is less than 0.9,wherein the electrolyte is a one-phase solution at a temperature ranging from about −
30°
C. to about 80°
C.
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Accused Products
Abstract
Provided are electrochemical cells and electrolytes used to build such cells. The electrolytes include ion-supplying salts and fluorinated solvents capable of maintaining single phase solutions with the salts at between about −30° C. to about 80° C. The fluorinated solvents, such as fluorinated carbonates, fluorinated esters, and fluorinated esters, are less flammable than their non-fluorinated counterparts and increase safety characteristics of cells containing these solvents. The amount of fluorinated solvents in electrolytes may be between about 30% and 80% by weight not accounting weight of the salts. Fluorinated salts, such as fluoroalkyl-substituted LiPF6, fluoroalkyl-substituted LiBF4 salts, linear and cyclic imide salts as well as methide salts including fluorinated alkyl groups, may be used due to their solubility in the fluorinated solvents. In some embodiments, the electrolyte may also include a flame retardant, such as a phosphazene or, more specifically, a cyclic phosphazene and/or one or more ionic liquids.
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Citations
20 Claims
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1. An electrolyte for use in an electrochemical cell, the electrolyte comprising:
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an electrolyte salt comprising at least one carbon atom and at least two fluoride atoms and is selected from the group consisting of; i) fluoroalkyl-substituted LiPF6 salts having a general structure LiPFxR1-x, wherein x is from 1 to 5 and wherein at least one R is a fluorinated alkyl having a chain length of from 1 to 8; ii) fluoroalkyl-substituted LiBF4 salts having a general structure LiBFxR1-x, wherein x is from 1 to 4 and wherein at least one R is a fluorinated alkyl having a chain length of from 1 to 8; iii) linear imide salts having a general structure LiN(—
SO2—
R)2, wherein at least one R is a fluorinated alkyl having a chain length of from 1 to 8;iv) cyclic imide salts having a general structure LiN(—
SO2—
R—
), wherein R is fluorinated alkyl having a chain length of from 1 to 8; andv) methide salts having a general structure LiC(—
SO2—
R)3, wherein at least one R is fluorinated alkyl with a chain length of from 1 to 8;a fluorinated solvent being present at a concentration of between about 30% and 80% by weight excluding a weight of the electrolyte salt, wherein the fluorinated solvent has a general structure CxFyHzOi such that x is an integer ranging from 3 to 15, y is an integer ranging from 1 to 30, z is an integer ranging from 0 to 15, and i is an integer ranging from 1 to 5; and a non-fluorinated solvent selected from the group consisting of an ester, an ether, and a carbonate wherein a weight ratio of the non-fluorinated solvents to the fluorinated solvent is less than 0.9, wherein the electrolyte is a one-phase solution at a temperature ranging from about −
30°
C. to about 80°
C. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An electrolyte for use in an electrochemical cell, the electrolyte comprising:
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LiN(SO2CF2CF3)2 being present at a concentration between about 0.6M and about 2M, 3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexane being present at a concentration of between about 60% and 80% by weight excluding a weight of an electrolyte salt; ethyl butyrate being present at a concentration of between about 10% and 30% by weight excluding a weight of the electrolyte salt; and a cyclic phosphazene being present at a concentration of between about 5% and 15% by weight excluding a weight of the electrolyte salt.
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20. An electrochemical cell comprising:
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a positive electrode; a negative electrode; an electrolyte providing ionic exchange between the positive electrode and negative electrode and comprising; an electrolyte salt comprising at least one carbon atom and at least two fluoride atoms and is selected from the group consisting of; i) fluoroalkyl-substituted LiPF6 salts having a general structure LiPFxR1-x, wherein x is from 1 to 5 and wherein at least one R is a fluorinated alkyl having a chain length of from 1 to 8; ii) fluoroalkyl-substituted LiBF4 salts having a general structure LiBFxR1-x, wherein x is from 1 to 4 and wherein at least one R is an fluorinated alkyl having a chain length of from 1 to 8; iii) linear imide salts having a general structure LiN(—
SO2—
R)2, wherein at least one R is a fluorinated alkyl having a chain length of from 1 to 8;iv) cyclic imide salts having a general structure LiN(—
SO2—
R—
), wherein R is fluorinated alkyl having a chain length of from 1 to 8; andv) methide salts having a general structure LiC(—
SO2—
R)3, wherein at least one R is fluorinated alkyl with a chain length of from 1 to 8;a fluorinated solvent being present at a concentration of between about 30% and 80% by weight excluding a weight of the electrolyte salt, wherein the fluorinated solvent has a general structure CxFyHzOi such that x is an integer ranging from 3 to 15, y is an integer ranging from 1 to 30, z is an integer ranging from 0 to 15, and i is an integer ranging from 1 to 5; and a non-fluorinated solvent selected from the group consisting of an ester, an ether, and a carbonate wherein a weight ratio of the non-fluorinated solvents to the fluorinated solvent is less than 0.9, wherein the electrolyte is a one-phase solution at a temperature ranging from about −
30°
C. to about 80°
C.
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Specification