Two-electron high potential and high capacity redox active molecules for energy storage applications

1. A non-aqueous redox flow battery comprising:

a catholyte comprising a two-electron redox active compound represented by Formula I, II, III, or a mixture of two or more thereof;

wherein each R group is independently H, OR 20 , NO 2 , F, Cl, Br, I, alkyl, haloalkyl, aryl, amino, P(═O)R 20 R 21 , P(═O)(—OR 20 )(—OR 21 ), phosphate, —C(O)R 21 , —S(O) 2 R 21 , or X, wherein X is a group of formula IV-A or IV-B;

wherein

R 11 is H, alkyl, haloalkyl, or aryl;

each R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , and R 19 is independently H, F, Cl, Br, I, NO 2 , alkyl, or alkoxy; m is 0 to 12, n is 0 to 12, and p is 1 to 12;

each R 20 is H, alkyl, or aryl; and

each R 21 is alkyl, or aryl;

wherein the compound of formula I, II, or III has two independent R groups having formula X.

2. The non-aqueous redox flow battery of claim 1 , wherein the active compound has the following structure:

3. The non-aqueous redox flow battery of claim 1 , wherein the active compound has the following structure:

4. The non-aqueous redox flow battery of claim 1 , wherein the active compound has the following structure:

5. The non-aqueous redox flow battery of claim 1 , wherein the two R groups having formula X are the same.

6. The non-aqueous redox flow battery of claim 1 , wherein m is 0.

7. The non-aqueous redox flow battery of claim 1 , wherein m is 1 to 4, n is 0 to 4, and p is 1 to 4.

8. The non-aqueous redox flow battery of claim 1 , wherein X is a moiety of formula IV-A, m is 0, and n is 0.

9. The non-aqueous redox flow battery of claim 1 , wherein each X independently is —OCH 3 , —OCH 2 CH 3 , —(CH 2 ) 1-3 O(CH 2 CH 2 O) 1-3 CH 3 , or

—O(CH 2 CH 2 O) 1-3 CH 3 .

10. The non-aqueous redox flow battery of claim 1 , wherein each X independently is —OCH 3 , —OCH 2 CH 3 , —CH 2 OCH 2 CH 2 OCH 3 , or

—OCH 2 CH 2 OCH 3 .

11. The non-aqueous redox flow battery of claim 1 , wherein the active compound is represented by Formula I-A, I-B, or II-D, has the following structure:

wherein both X groups are independently —OCH 3 , —OCH 2 CH 3 , or —OCH 2 CH 2 OCH 3 .

12. The non-aqueous redox flow battery of claim 1 , wherein each R group is independently H, F, Cl, Br, I, or alkyl.

13. The non-aqueous redox flow battery of claim 1 , wherein the active compound is represented by one or more of the following formula;

or a mixture of two or more thereof.

14. The non-aqueous redox flow battery of claim 1 , wherein the active compound is 1,4-dimethoxynaphthalene (DMN) or 2-ethyl-9,10-dimethoxyanthracene (EDMA).

15. The non-aqueous redox flow battery of claim 1 further comprising a separator positioned between the anolyte and the catholyte.

16. The non-aqueous redox flow battery of claim 1 , wherein the active compound is present in the catholyte at a concentration from about 0.001 M to about 5.0 M.

17. The non-aqueous redox flow battery of claim 1 further comprising a solvent and an electrolyte salt.

18. The non-aqueous redox flow battery of claim 1 further comprising an anode, wherein the anode comprises Li, Na, or Mg.

19. The non-aqueous redox flow battery of claim 1 further comprising an anolyte, wherein the anolyte comprises viologen or quinoxaline.

20. A method of operating a redox flow battery, the method comprising:

providing a redox flow battery comprising:

a catholyte comprising a two-electron redox active compound represented by Formula I, II, III, or a mixture of two or more thereof;

wherein each R group is independently H, OR 20 , NO 2 , F, Cl, Br, I, alkyl, haloalkyl, aryl, amino, P(═O)R 20 R 21 , P(═O)(—OR 20 )(—OR 21 ), phosphate, —C(O)R 21 , —S(O) 2 R 21 , or X, wherein X is a group of formula IV-A or IV-B;

wherein

R 11 is H, alkyl, haloalkyl, or aryl;

each R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , and R 19 is independently H, F, Cl, Br, I, NO 2 , alkyl, or alkoxy; m is 0 to 12, n is 0 to 12, and p is 1 to 12;

each R 20 is H, alkyl, or aryl; and

each R 21 is alkyl, or aryl;

wherein the compound of formula I, II, or III has two independent R groups having formula X; and

operating the redox flow battery at a voltage sufficient to access the second electron redox couple of the compound of formula I, II, or III.