Electrolyte for redox flow battery, and redox flow battery

• US 20040191623A1
• Filed: 04/22/2004
• Published: 09/30/2004
• Est. Priority Date: 06/07/2001
• Status: Active Grant

• Current Assignee: Kansai Electric Power Company Incorporated, Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Kansai Electric Power Company Incorporated, Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Tokuda, Nobuyuki, Nakaishi, Hiroyuki, Kubata, Michiru
• Granted Patent: US 7,258,947 B2
• Time in Patent Office: Days
• US Class Current: 429/189
• CPC Class Codes: H01M 2300/0008 Phosphoric acid-based
• CPC Class Codes: H01M 2300/0011 Sulfuric acid-based
• CPC Class Codes: H01M 8/188 by recharging of redox couples containing fluids; Redox flow type batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

The present invention provides electrolyte that can suppress reduction of battery efficiencies and capacities with increased cycles of charge/discharge of the battery, a method for producing the same, and a redox flow battery using the same electrolyte. The redox flow battery uses the electrolyte having a NH₄ content of not more than 20 ppm and a relation of Si concentration (ppm)×electrolyte quantity (m³)/electrode area (m²) of less than 5 ppm·m³/m². By limiting a quantity of contaminants in the electrolyte, a clogging of carbon electrodes to cause reduction of the battery performances with increased charge/discharge operations can be suppressed.

Claims

1. Redox flow battery electrolyte having a NH₄ content of not more than 20 ppm.

2. The redox flow battery electrolyte according to claim 1 further having a Si content of not more than 40 ppm.

3. The redox flow battery electrolyte according to claim 2, wherein the Si content is not more than 10 ppm.

4. The redox flow battery electrolyte according to any one of claims 1 to 3, wherein a vanadium ion concentration is in the range of 1 to 3 mol/L, a free sulfuric acid concentration is in the range of 1 to 4 mol/L, and a phosphoric acid concentration is in the range of 10⁻

4 to 0.71 mol/L.

5. A redox flow battery using the electrolyte according to any of claims 1 to 4.

6. A redox flow battery using electrolyte having a NH₄ content of not more than 20 ppm and a relation of Si concentration (ppm)×

electrolyte quantity (m³)/electrode area (m²) of less than 5 ppm·

m³/m².

7. A method for producing a redox flow battery electrolyte, wherein contaminants are removed by filtering the electrolyte through a filter having a pore size of not more than 0.5 μ

m.

8. A method for producing a redox flow battery electrolyte, wherein contaminants are removed by charge and discharge operation using a filtering cell having an equivalent structure to an operating cell.