Annulated tetra-substituted hydroquinone ether-based redox shuttle additives for lithium-ion batteries

1. An electrolyte for a lithium-ion electrochemical cell comprising a non-aqueous solution of a lithium salt and a redox shuttle compound, wherein the redox shuttle compound comprises:

(a) —OR groups at carbons 1 and 4 of a benzene ring;

(b) a first hydrocarbon ring fused to carbons 2 and 3 of the benzene ring; and

(c) a second hydrocarbon ring fused to the carbons 5 and 6 of the benzene ring; and

wherein either (i) the first and second hydrocarbon rings together with the benzene ring constitute two fused benzobicyclo[2.2.2]octane ring systems; or (ii) the first and second hydrocarbon rings together with the benzene ring constitute two fused benzobicyclo[2.2.1]heptane ring systems sharing a common benzo core group; wherein the R of each —OR group independently is selected from C 1 to C 4 alkyl and C 1 to C 4 alkoxy-substituted C 1 to C 4 alkyl.

2. The electrolyte of claim 1 , wherein the first and second hydrocarbon rings each comprise at least one substituent selected from the group consisting of alkyl, alkoxy, hydroxyl, halogen, substituted-alkyl, and substituted-alkoxy; wherein each substituted-alkyl and substituted-alkoxy comprises an alkyl or alkoxy group, respectively, which is substituted by one of more substituent selected from the group consisting of halogen, hydroxy, alkoxy, cyano, aryl, carboxylic acid, carboxylic ester, and carboxylic amide.

3. The electrolyte of claim 1 , wherein the first and second hydrocarbon rings each are unsubstituted hydrocarbons.

4. The electrolyte of claim 1 , wherein the lithium salt comprises at least one salt selected from the group consisting of LiF 2 BC 2 O 4 , LiPF 6 , LiBF 4 , LiB(C 2 O 4 ) 2 , LiClO 4 , lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSi), and LiAsF 6 .

5. The electrolyte of claim 1 , wherein the lithium salt and the redox shuttle are dissolved in at least one non-aqueous solvent selected from the group consisting of a linear dialkyl carbonate, a cyclic alkylene carbonate, a sulfolane, a sulfone, a fluoro-substituted linear dialkyl carbonate, a fluoro-substituted cyclic alkylene carbonate, a fluoro-substituted sulfolane, and a fluoro-substituted sulfone.

6. The electrolyte of claim 1 , wherein the redox shuttle comprises a compound of Formula (I):

wherein:

each R independently is C 1 to C 4 alkoxy-substituted C 1 to C 4 alkyl;

X 1 is —C(R 2 ) 2 C(R 2 ) 2 —;

X 2 is —C(R 2 ) 2 C(R 2 ) 2 —or —C(R 2 ) 2 —;

each of X 3 and X 4 is —C(R 3 ) 2 C(R 3 ) 2 —or —C(R 3 ) 2 —; and

each R 1 , R 2 , and R 3 independently is selected from H, alkyl, substituted-alkyl, alkoxy, substituted-alkoxy, halogen, and hydroxyl; wherein each substituted-alkyl and substituted-alkoxy comprises an alkyl or alkoxy group, respectively, which is substituted by one of more substituent selected from the group consisting of halogen, hydroxy, alkoxy, cyano, aryl, carboxylic acid, carboxylic ester, and carboxylic amide;

with the provisos that:

(a) if X 2 is —C(R 2 ) 2 —, then at least one of X 3 and X 4 is —C(R 3 ) 2 —, and at least one of X 3 and X 4 is —C(R 3 ) 2 C(R 3 ) 2 —; and

(b) if X 2 is —C(R 2 ) 2 C(R 2 ) 2 —, then both of X 3 and X 4 are —C(R 3 ) 2 C(R 3 ) 2 —.

7. The electrolyte of claim 6 , wherein each R is 2-methoxyethyl.

8. The electrolyte of claim 6 , wherein each R 1 , R 2 , and R 3 independently is selected from H, C 1 to C 4 alkyl, and C 1 to C 4 alkoxy.

9. The electrolyte of claim 6 , wherein each R 1 , R 2 , and R 3 is H.

10. The electrolyte of claim 1 , wherein the first and second hydrocarbon rings together with the benzene ring constitute two benzobicyclo[2.2.2]octane ring systems, and the redox shuttle comprises a compound of Formula (II):

wherein:

the first hydrocarbon ring and the second hydrocarbon ring each optionally comprises one or more substituents R 4 ;

x is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10;

each R independently is C 1 to C 4 alkoxy-substituted C 1 to C 4 alkyl; and

each R 4 independently is selected from alkyl, substituted-alkyl, alkoxy, substituted-alkoxy, halogen, and hydroxyl;

wherein each substituted-alkyl and substituted-alkoxy comprises an alkyl or alkoxy group, respectively, which is substituted by one of more substituent selected from the group consisting of halogen, hydroxy, alkoxy, cyano, aryl, carboxylic acid, carboxylic ester, and carboxylic amide.

11. The electrolyte of claim 10 , wherein x is 0.

12. The electrolyte of claim 1 , wherein the first and second hydrocarbon rings together with the benzene ring constitute two benzobicyclo[2.2.2]heptane ring systems, and the redox shuttle comprises a compound of Formula (III):

wherein:

the first hydrocarbon ring and the second hydrocarbon ring each optionally comprises one or more substituents R 5 ;

y is 0, 1, 2, 3, 4, 5, 6, 7, or 8;

each R independently is C 1 to C 4 alkoxy-substituted C 1 to C 4 alkyl; and

each R 5 independently is selected from alkyl, substituted-alkyl, alkoxy, substituted-alkoxy, halogen, and hydroxyl;

wherein each substituted-alkyl and substituted-alkoxy comprises an alkyl or alkoxy group, respectively, which is substituted by one of more substituent selected from the group consisting of halogen, hydroxy, alkoxy, cyano, aryl, carboxylic acid, carboxylic ester, and carboxylic amide.

13. The electrolyte of claim 12 , wherein y is 0.

14. The electrolyte of claim 1 , wherein the first and second hydrocarbon rings together with the benzene ring constitute two benzobicyclo[2.2.2]heptane ring systems, and the redox shuttle comprises a compound of Formula (IV):

wherein:

the first hydrocarbon ring and the second hydrocarbon ring each optionally comprises one or more substituents R 5 ;

z is 0, 1, 2, 3, 4, 5, 6, 7, or 8;

each R independently is C 1 to C 4 alkoxy-substituted C 1 to C 4 alkyl; and

each R 6 independently is selected from alkyl, substituted-alkyl, alkoxy, substituted-alkoxy, halogen, and hydroxyl;

wherein each substituted-alkyl and substituted-alkoxy comprises an alkyl or alkoxy group, respectively, which is substituted by one of more substituent selected from the group consisting of halogen, hydroxy, alkoxy, cyano, aryl, carboxylic acid, carboxylic ester, and carboxylic amide.

15. The electrolyte of claim 1 , wherein the redox shuttle is selected from a compound of Formula (V), a compound of Formula (VI) or a combination thereof:

wherein each R is C 1 to C 4 alkoxy-substituted C 1 to C 4 alkyl.

16. The electrolyte of claim 1 , wherein the redox shuttle is selected from 9,10-bis(2-methoxyethoxy)-1,2,3,4,5,6,7,8-octahydro-1,4:5,8-dimethanoanthracene (BODMA), 9,10-bis(2-methoxyethoxy)-1,2,3,4,5,6,7,8-octahydro-1,4:5,8-diethanoanthracene (BODEA), and a combination thereof.

17. A lithium-ion electrochemical cell comprising an anode, a cathode, and an a porous membrane therebetween, wherein the electrolyte of claim 1 contacts the anode, the cathode, and the membrane.

18. A lithium-ion battery comprising two or more electrochemical cells of claim 17 , wherein the cells are connected in series, parallel, or both series and parallel.