High solubility iron hexacyanides

Patent metadata

Field	Value
Publication number	US-2016276696-A1
Application number	US-201615166174-A
Country	US
Kind code	A1
Filing date	May 26, 2016
Priority date	Aug 15, 2012
Publication date	Sep 22, 2016
Grant date	—

Abstract

Stable solutions comprising high concentrations of charged coordination complexes, including iron hexacyanides are described, as are methods of preparing and using same in chemical energy storage systems, including flow battery systems. The use of these compositions allows energy storage densities at levels unavailable by other iron hexacyanide systems.

First claim

What is claimed is the following:

1 . A method comprising:
dissolving Na 4 [Fe(CN) 6 ] and K 4 [Fe(CN) 6 ] in an amount of aqueous solvent, so as to provide a concentration of Fe(CN) 6 4− in the aqueous solvent that exceeds the concentration of Fe(CN) 6 4− in either a saturated solution of Na 4 [Fe(CN) 6 ] or a saturated solution of K 4 [Fe(CN) 6 ] in the aqueous solvent at the same temperature.

2 . The method of claim 1 , wherein the aqueous solvent has a pH ranging between about 7 and about 14.

3 . The method of claim 1 , wherein the aqueous solvent has a pH ranging between about 8 and about 13.

4 . The method of claim 1 , wherein Na 4 [Fe(CN) 6 ] and K 4 [Fe(CN) 6 ] are co-mixed as solids with the aqueous solvent.

5 . The method of claim 1 , wherein Na 4 [Fe(CN) 6 ] is added as a solid to a solution of K 4 [Fe(CN) 6 ] in the aqueous solvent.

6 . The method of claim 1 , wherein K 4 [Fe(CN) 6 ] is added as a solid to a solution of Na 4 [Fe(CN) 6 ] in the aqueous solvent.

7 . The method of claim 1 , wherein the aqueous solvent is substantially free of a co-solvent.

8 . The method of claim 1 , wherein the Fe(CN) 6 4− is present in the aqueous solvent at a concentration ranging between about 1 M and about 3 M.

9 . The method of claim 1 , wherein a molar ratio of sodium ions to potassium ions in the aqueous solvent after dissolution of the Na 4 [Fe(CN) 6 ] and K 4 [Fe(CN) 6 ] ranges between about 1:10 and about 10:1.

10 . The method of claim 9 , wherein the molar ratio of sodium ions to potassium ions ranges between about 0.9:1 and about 1.1:1.

11 . The method of claim 1 , wherein the aqueous solvent contains additional sodium and potassium ions.

12 . A method comprising:
dissolving H 4 [Fe(CN) 6 ], NaOH and KOH in water, so as to provide a concentration of Fe(CN) 6 4− in an aqueous solution that exceeds the concentration of Fe(CN) 6 4− in either a saturated solution of Na 4 [Fe(CN) 6 ] or a saturated solution of K 4 [Fe(CN) 6 ] in water at the same temperature.

13 . The method of claim 12 , wherein the aqueous solution is substantially free of a co-solvent.

14 . The method of claim 12 , wherein the Fe(CN) 6 4− is present in the aqueous solution at a concentration ranging between about 1 M and about 3 M.

15 . The method of claim 12 , wherein a molar ratio of sodium ions to potassium ions in the aqueous solution ranges between about 1:10 and about 10:1.

16 . The method of claim 15 , wherein the molar ratio of sodium ions to potassium ions ranges between about 0.9:1 and about 1.1:1.

17 . A method comprising:
dissolving Ca 4 [Fe(CN) 6 ], NaOH and KOH in water, so as to provide a concentration of Fe(CN) 6 4− in an aqueous solution that exceeds the concentration of Fe(CN) 6 4− in either a saturated solution of Na 4 [Fe(CN) 6 ] or a saturated solution of K 4 [Fe(CN) 6 ] in water at the same temperature.

18 . The method of claim 17 , further comprising:
removing precipitated Ca(OH) 2 from the aqueous solution.

19 . The method of claim 17 , wherein the aqueous solution is substantially free of a co-solvent.

20 . The method of claim 17 , wherein the Fe(CN) 6 4− is present in the aqueous solution at a concentration ranging between about 1 M and about 3 M.

21 . The method of claim 17 , wherein a molar ratio of sodium ions to potassium ions in the aqueous solution ranges between about 1:10 and about 10:1.

22 . The method of claim 21 , wherein the molar ratio of sodium ions to potassium ions ranges between about 0.9:1 and about 1.1:1.

Assignees

• Lockheed Martin Advanced Energy Storage Llc

Inventors

• Esswein Arthur J
• Goeltz John
• Amadeo Desiree

Classifications

• H01M8/188 Primary

  by recharging of redox couples containing fluids; Redox flow type batteries · CPC title

• H01M8/20

  Indirect fuel cells, e.g. fuel cells with redox couple being irreversible (H01M8/18 takes precedence) · CPC title

• H01M8/222 Primary

  Fuel cells in which the fuel is based on compounds containing nitrogen, e.g. hydrazine, ammonia · CPC title

• C01C3/12 Primary

  Simple or complex iron cyanides · CPC title

• H01M2300/0002

  Aqueous electrolytes · CPC title