Polyoxometalate-modified carbon electrodes and uses therefor in capacitors

• US 4,633,372 A
• Filed: 08/26/1985
• Issued: 12/30/1986
• Est. Priority Date: 08/26/1985
• Status: Expired due to Fees

• Current Assignee: Standard Oil Company AKA Sohio Cleveland Oh
• Original Assignee: Standard Oil Company (BP PLC)
• Inventors: Desmond, Michael J., Cuellar, Edward A., Currie, John C., Calahan, James L.
• Primary Examiner(s): Chapman, Terryence
• Application Number:
  US06/769,925
• Time in Patent Office: 491 Days
• Field of Search: 204/290 R, 204/294, 361/305, 361/433 A, 429/218
• US Class Current: 361/502
• CPC Class Codes: H01G 11/32 Carbon-based
• CPC Class Codes: H01G 11/34 characterised by carbonisation or activation of carbon
• CPC Class Codes: H01G 11/52 Separators
• CPC Class Codes: H01G 11/54 Electrolytes
• CPC Class Codes: H01M 10/05 Accumulators with non-aqueous electrolyte H01M10/39 takes precedence
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: H01M 4/583 Carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors

Abstract

Improved activated carbon electrodes are disclosed, which electrodes have increased charge storage capacity. Such improved electrodes are incorporated into energy storage devices such as electrical double layer capacitors. The improved charge storage capacity is due to the adsorption of polyoxometalate compounds into the activated carbon, which compounds are capable of reversible redox reactions and so provide a secondary charge storage mechanism without decreasing the charge storage ability of the activated carbon.

Claims

1. An improved carbon-based electrode comprising an activated carbon electrode having absorbed throughout the electrode structure a polyoxometalate compound represented by the formula

View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15)

2. The electrode in accordance with claim 1 wherein L is at least one element of the group consisting of P, As, Si, Al, H, Ge, Ga and B;

M is at least one element of the group Zn, Ti, Mn, Fe, Co, Ni, Rh, Zr and Re; and

J is at least one metal of the group consisting of Mo, W and V; and

wherein l ranges from zero to about 4;

m ranges from zero to about 6;

z ranges from about 6 to about 24; and

y ranges from about 18 to about 80.

3. The electrode in accordance with claim 1 wherein said polyoxometalate is a hexametalate.

4. The electrode in accordance with claim 1 wherein said polyoxometalate is a Keggin anion.

5. The electrode in accordance with claim 4 wherein said polyoxometalate is H₄ [PVMo₁₁ O₄₀ ] which contains a Keggin anion.

6. The electrode in accordance with claim 4 wherein said polyoxometalate is H₅ [PV₂ Mo₁₀ O₄₀ ] which contains a Keggin anion.

7. The electrode in accordance with claim 6 wherein said polyoxometalate is (NH₄)₆ [P₂ Mo₁₈ O₆₂ ] which contains a Dawson anion.

8. The electrode in accordance with claim 1 wherein said polyoxometalate is a Dawson anion.

9. The electrode in accordance with claim 1 wherein said activated carbon has a BET surface area of from about 100 m² /g to about 2000 m² /g.

10. The electrode in accordance with claim 1 wherein said activated carbon has a BET surface area of from about 500 m² /g to about 1500 m² /g.

11. The electrode in accordance with claim 1 wherein said polyoxometalate is absorbed by said activated carbon up to about forty weight percent, based on the total weight of said improved electrode.

12. The electrode in accordance with claim 1 wherein said polyoxometalate is absorbed by said activated carbon from about five weight percent to about twenty-five weight percent, based on the total weight of said improved electrode.

15. The energy storage device in accordance with claim 11 wherein L is at least one element of the group consisting of P, As, Si, Al, H, Ge, Ga and B;

M is at least one element of the group Zn, Ti, Mn, Fe, Co, Ni, Rh, Zr and Re; and

J is at least one metal of the group consisting of Mo, W and V; and

wherein l ranges from zero to about 4;

m ranges from zero to about 6;

z ranges from about 6 to about 24; and

y ranges from about 24 to about 80.

13. An energy storage device comprising a pair of electrodes electrically isolated from each other, an electrolyte in contact with the electrodes, and means for collecting electrical current therefrom;

at least one electrode comprising an activated carbon electrode having a polyoxometalate compound absorbed therein.

14. The energy storage device in accordance with claim 13 wherein said polyoxometalate compound is represented by the formula:

space="preserve" listing-type="equation">A.sub.a [L.sub.l M.sub.m J.sub.z O.sub.y ]

wherein

A is at least one ion selected from the group consisting of hydrogen, the Group I-A to VIII-A or I-B to VII-B elements, the rare earths and actinides, ammonium, alkyl ammonium, alkyl phosphonium and alkyl arsonium;

L is at least one element selected from the group consisting of hydrogen and Group III-B to VII-B elements;

M is at least one metal selected from the group consisting of Group I-A to IV-A metals, Group VII-A to II-B metals, the rare earths and actinides; and

J is at least one metal selected from the group consisting of Group V-A metals and Group VI-A metals; and

wherein

a is a number which when multiplied by the valence of A will balance the charge on the polyoxometalate complex within the brackets;

l is a number ranging from zero to about 20;

m is a number ranging from zero to about 20;

z is a number ranging from about 1 to about 50; and

y is a number ranging from about 7 to about 150.

16. The energy storage device in accordance with claim 13 wherein said polyoxometalate is a hexametalate.

17. The energy storage device in accordance with claim 13 wherein said polyoxometalate is a Keggin anion.

18. The energy storage device in accordance with claim 13 wherein said polyoxometalate is a Dawson anion.

19. The energy storage device in accordance with claim 13 wherein said polyoxometalate is absorbed by said activated carbon up to about forty weight percent, based on the total weight of said improved electrode.

20. An electric double layer capacitor comprising a housing, at least one pair of spaced activated carbon electrodes in the housing, an electrolyte in contact with said electrodes, and an ionically conductive separator interposed between said electrodes and in contact therewith, the electrodes comprising activated carbon having a polyoxometalate compound absorbed therein.

21. The capacitor in accordance with claim 20 wherein said polyoxometalate compound is represented by the formula:

space="preserve" listing-type="equation">A.sub.a [L.sub.l M.sub.m J.sub.z O.sub.y ]

wherein

A is at least one ion selected from the group consisting of hydrogen, the Group I-A to VIII-A or I-B to VII-B elements, the rare earths and actinides, ammonium, alkyl ammonium, alkyl phosphonium and alkyl arsonium;

L is at least one element selected from the group consisting of hydrogen and Group III-B to VII-B elements;

M is at least one metal selected from the group consisting of Group I-A to IV-A metals, Group VII-A to II-B metals, the rare earths and actinides; and

J is at least one metal selected from the group consisting of Group V-A metals and Group VI-A metals; and

wherein

a is a number which when multiplied by the valence of A will balance the charge on the polyoxometalate complex within the brackets;

l is a number ranging from zero to about 20;

m is a number ranging from zero to about 20;

z is a number ranging from about 1 to about 50; and

y is a number ranging from about 7 to about 150.

22. The capacitor in accordance with claim 21 wherein L is at least one element of the group consisting of P, As, Si, Al, H, Ge, Ga and B;

M is at least one element of the group consisting of Zn, Ti, Mn, Fe, Co, Ni, Rh, Zr and Re; and

J is at least one metal of the group consisting of Mo, W and V; and

wherein l ranges from zero to about 4;

m ranges from zero to about 6;

z ranges from about 6 to about 24; and

y ranges from about 18 to about 80.

23. The capacitor in accordance with claim 20 wherein said polyoxometalate is a hexametalate.

24. The capacitor in accordance with claim 20 wherein said polyoxometalate is a Keggin anion.

25. The capacitor in accordance with claim 20 wherein said polyoxometalate is a Dawson anion.