Carbon electrode material for a vanadium-based redox-flow battery

• US 6,509,119 B1
• Filed: 06/08/2000
• Issued: 01/21/2003
• Est. Priority Date: 06/11/1999
• Status: Expired due to Term

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Inoue, Makoto, Kobayashi, Masaru, Takase, Satoshi
• Primary Examiner(s): WEINER, LAURA S
• Application Number:
  US09/590,629
• Time in Patent Office: 957 Days
• Field of Search: 429/105, 429/231.8, 429/233, 423/445.R
• US Class Current: 429/231.8
• CPC Class Codes: C01B 32/20 Graphite
• CPC Class Codes: C01P 2002/60 Compounds characterised by their crystallite size
• CPC Class Codes: C01P 2002/78 by stacking-plane distances or stacking sequences
• CPC Class Codes: C01P 2006/80 Compositional purity
• CPC Class Codes: H01M 4/96 Carbon-based electrodes
• 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

Abstract

The carbon electrode material of the present invention is used for a vanadium redox-flow cell. The carbon electrode material has quasi-graphite crystal structure in which <002> spacing obtained by X-ray wide angle analysis is 3.43 to 3.60 Å, size of a crystallite in c axial direction is 15 to 33 Å and size of crystallite in a axial direction is 30 to 70 Å. In addition, an amount of surface acidic functional groups obtained by XPS surface analysis is 0.1 to 1.2% and total number of surface bound-nitrogen atoms is 5% or smaller relative to total number of surface carbon atoms. The carbon electrode materials formed of a non-woven fabric of a carbonaceouss fiber is preferable.

Claims

1. A carbon electrode material for a vanadium-based redox-flow battery, comprising quasi-graphite crystal structure, wherein <

002>

spacing is 3.45 to 3.50 Å

, size of a crystallite in c axial direction is 20 to 30 Å

, and size of a crystallite in a axial direction is 30 to 70 Å

, each obtained by X-ray wide angle analysis,

and having surface property obtained by XPS surface analysis wherein an amount of surface acidic functional groups is 0.1 to 1.2% relative to total number of surface carbon atoms and number of surface bound-nitrogen atoms is 5% or smaller relative to total number of surface carbon atoms, and wherein the carbon electrode material is formed into a non-woven fabric of a carbonaceous fiber, and the non-woven fabric has a bulk density of 0.05 to 0.17 g/cm³.

2. The carbon electrode material according to claim 1, wherein said amount of surface acidic functional groups is 0.2 to 1.0% relative to total number of surface carbon atoms and said number of surface bound-nitrogen atoms is 3% or smaller relative to total number of surface carbon atoms.

3. The carbon electrode material according to claim 1, wherein said <

002>

spacing is 3.45 to 3.50 Å

, said size of a crystallite in c axial direction is 20 to 30 Å and

said size of a crystallite in a axial direction is 45 to 65 Å

.

4. The carbon electrode material according to claim 1, wherein a half value half width of a peak at 1360 cm⁻

1 is 30 to 60 cm<sup>−

1</sup>, a half value half width of a peak at 1580 cm<sup>−

1</sup> is 30 to 45 cm<sup>−

1</sup>, and a ratio R of peak intensity Ia at 1360 cm<sup>−

1</sup> and peak intensity Ig at 1580 cm<sup>−

1</sup> (=Ia/Ig) is 0.7 to 1.0 each obtained by a laser Raman spectroscopic method.

5. The carbon electrode material according to claim 1, wherein a stacked structure ratio based on a peak intensity of <

002>

diffraction obtained by X-ray wide angle analysis is 0.50 to 0.90.

6. The carbon electrode material according to claim 1, wherein number of surface carbon atoms which are double-bound with nitrogen obtained by XPS surface analysis is 0.3 to 3.0% relative to total number of surface carbon atoms.

7. The carbon electrode material according to claim 6, wherein number of surface quaternary ammonium nitrogen atoms obtained by XPS surface analysis is 1.0% or smaller relative to total number of surface carbon atoms.

8. The carbon electrode material according to claim 1, wherein number of surface neutral carbon atoms obtained by XPS surface analysis is 80 to 95% relative to total number of surface carbon atoms.

9. The carbon electrode material according to claim 1, wherein the viscosity of an electrolysis solution of the battery is 0.005 Pa·

s or greater at 25°

C.

10. The carbon electrode material according to claim 1, wherein an electrolysis solution of the battery contains vanadium ion at an amount of 1.5 mol/l.

11. The carbon electrode material according to claim 1, wherein the carbon electrode material is formed into a non-woven fabric of a carbonaceous fiber, the non-woven fabric has compressibility of 10 to 25% and compression modulus of 80% or greater each obtained according to JIS L1096 (1990).

12. The carbon electrode material according to claim 11, said non-woven fabric has one or more concave groove formed on one face thereof.

13. The carbon electrode material according to claim 1, said non-woven fabric has one or more concave groove formed on one face thereof.

14. A battery comprising an ion exchange membrane, a pair of the carbon electrode material of claim 1, and collector plates in contact with the carbon electrode material, wherein one member of the electrode material pair is disposed on each side of the ion exchange membrane.