Multi-electron redox active molecules for energy storage applications

1. A non-aqueous redox flow battery comprising:

a catholyte comprising a compound of formula (I) or a compound of formula (II):

wherein:

X 1 is a moiety of formula I-A or I-B:

 and

X 2 and X 3 are independently —CH 2 CH 2 OCH 3 , —(CH 2 CH 2 O) 2 CH 3 or —CH 2 CH 2 CH═CH 2 ; or wherein X 1 , X 2 , and X 3 are each moieties of formula I-A;

R 1 , R 2 , R 3 , and R 4 are each independently H, —OR 10 , —NO 2 , F, Cl, Br, I, alkyl, haloalkyl, aryl, heteroalkyl, phosphate, P(═O)(R 10 ) 2 , P(═O)(OR 10 ) 2 , —C(O)R 11 , or —S(O) 2 R 11 ;

each R 5 and R 6 are independently H, alkyl, alkenyl, haloalkyl, heteroalkyl, or aryl;

each R 10 is H, alkyl, heteroalkyl, or aryl;

each R 11 is H, alkyl, heteroalkyl or aryl; and

m and n are independently 1 to 8.

2. The non-aqueous redox flow battery of claim 1 , wherein X 1 is a moiety of formula I-A.

3. The non-aqueous redox flow battery of claim 1 , wherein R 1 , R 2 , R 3 , and R 4 are independently H, F, Cl, Br, I, alkyl, haloalkyl, or heteroalkyl.

4. The non-aqueous redox flow battery of claim 1 , wherein R 1 , R 2 , R 3 , and R 4 are independently H, F, —C 1 -C 6 alkyl, or —C 1 -C 7 heteroalkyl.

5. The non-aqueous redox flow battery of claim 1 , wherein R 5 and R 6 are independently —C 1 -C 6 alkyl, —C 1 -C 7 heteroalkyl, or —C 1 -C 6 alkenyl.

6. The non-aqueous redox flow battery of claim 1 , wherein R 5 and R 6 are CH 3 , —CH 2 CH 3 , —CH 2 CH 2 OCH 3 , —(CH 2 CH 2 O) 2 CH 3 , or —CH 2 CH 2 CH═CH 2 .

7. A redox flow battery comprising a compound represented by:

or a combination of any two or more thereof.

8. The non-aqueous redox flow battery of claim 1 , wherein the catholyte comprises a compound of formula (II).

9. The non-aqueous redox flow battery of claim 7 , wherein the compound is TFTMPD or TDPA.

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

11. The non-aqueous redox flow battery of claim 10 , wherein the electrolyte salt is present in the catholyte from about 0.1 M to about 2.0 M.

12. The non-aqueous redox flow battery of claim 10 , wherein the solvent comprises an organic carbonate, ether, ester, nitrile, or mixture of any two or more thereof.

13. The non-aqueous redox flow battery of claim 1 , wherein the catholyte further comprises a solvent and the compound of formula (I) or formula (II) is present at a concentration greater than any additional redox active compound in the solvent.

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

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

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

providing a redox flow battery comprising a compound of formula (I) or a compound of formula (II):

wherein:

X 1 is a moiety of formula I-A or I-B:

 and

X 2 and X 3 are independently —CH 2 CH 2 OCH 3 , —(CH 2 CH 2 O) 2 CH 3 or —CH 2 CH 2 CH═CH 2 ; or wherein X 1 , X 2 , and X 3 are each moieties of formula I-A;

R 1 , R 2 , R 3 , and R 4 are each independently H, —OR 10 , —NO 2 , F, Cl, Br, I, alkyl, haloalkyl, aryl, heteroalkyl, phosphate, P(═O)(R 10 ) 2 , P(═O)(OR 10 ) 2 , —C(O)R 11 , or —S(O) 2 R 11 ;

each R 5 and R 6 are independently H, alkyl, alkenyl, haloalkyl, heteroalkyl, or aryl;

each R 10 is H, alkyl, heteroalkyl, or aryl;

each R 11 is H, alkyl, heteroalkyl or aryl; and

m and n are independently 1 to 8; and

operating the redox flow battery at a voltage sufficient to access a second electron redox couple of the compound of Formula (I) or (II).

17. The redox flow battery of claim 7 , further comprising a solvent and an electrolyte salt.

18. The redox flow battery of claim 17 , wherein the electrolyte salt is present in the catholyte from about 0.1 M to about 2.0 M.

19. The redox flow battery of claim 17 , wherein the solvent comprises an organic carbonate, ether, ester, nitrile, or mixture of any two or more thereof.

20. The redox flow battery of claim 7 further comprising an anode and an anolyte, wherein the anode comprises Li, Na, or Mg, and the anolyte comprises a viologen or a quinoxaline.