Wet electrolytic capacitor

• US 7,480,130 B2
• Filed: 03/09/2006
• Issued: 01/20/2009
• Est. Priority Date: 03/09/2006
• Status: Expired due to Fees

• Current Assignee: AVX Corporation (Kyocera Corporation)
• Original Assignee: AVX Corporation (Kyocera Corporation)
• Inventors: Fife, James Allen, Sebald, Zebbie Lynn, Ning, Gang
• Primary Examiner(s): THOMAS, ERIC W
• Application Number:
  US11/372,461
• Publication Number:
  US 20070211412A1
• Time in Patent Office: 1,048 Days
• Field of Search: 361/503, 361/516, 361/508, 29/250.3
• US Class Current: 361/516
• CPC Class Codes: H01G 9/0425 specially adapted for cathode
• CPC Class Codes: H01G 9/06 Mounting in containers
• CPC Class Codes: H01G 9/145 Liquid electrolytic capacitors H01G11/00 takes precedence

Abstract

A wet electrolytic capacitor that includes an anode, cathode, and an electrolyte is provided. The cathode contains a plurality of metal particles disposed on a surface of a substrate and sinter bonded thereto. The metal particles have a median size of from about 20 to about 500 micrometers.

Claims

1. A wet electrolytic capacitor comprising:

an anode;

a cathode containing a plurality of metal particles disposed on a surface of a substrate and sinter bonded thereto, wherein the metal particles have a median size of from about 20 to about 500 micrometers, further wherein a coating overlies the metal particles and the substrate, the coating comprising electrochemically-active particles; and

an electrolyte disposed between the cathode and anode.

2. The wet electrolytic capacitor of claim 1, wherein the metal particles contain tantalum, niobium, aluminum, nickel, hafnium, titanium, copper, or silver.

3. The wet electrolytic capacitor of claim 1, wherein the metal particles comprise tantalum.

4. The wet electrolytic capacitor of claim 1, wherein the metal particles have a median size of from about 30 to about 400 micrometers.

5. The wet electrolytic capacitor of claim 1, wherein the metal particles have a median size of from about 50 to about 200 micrometers.

6. The wet electrolytic capacitor of claim 1, wherein the metal particles have a specific surface area of from about 0.05 to about 40 m²/g.

7. The wet electrolytic capacitor of claim 1, wherein the metal particles have a specific surface area of from about 0.5 to about 5 m²/g.

8. The wet electrolytic capacitor of claim 1, wherein at least a portion of the metal particles are spaced apart over the surface of the substrate.

9. The wet electrolytic capacitor of claim 1, wherein the metal particles are agglomerated.

10. The wet electrolytic capacitor of claim 1, wherein the electrochemically-active particles comprise carbon.

11. The wet electrolytic capacitor of claim 1, wherein the electrochemically-active particles comprise a metal.

12. The wet electrolytic capacitor of claim 11, wherein the metal is palladium.

13. The wet electrolytic capacitor of claim 1, wherein the electrochemically-active particles comprise a metal oxide.

14. The wet electrolytic capacitor of claim 13, wherein the metal oxide is RuO₂.

15. The wet electrolytic capacitor of claim 13, wherein the metal oxide is MnO₂.

16. The wet electrolytic capacitor of claim 1, wherein the coating further comprises a binder.

17. The wet electrolytic capacitor of claim 16, wherein the binder comprises adhesive particles.

18. The wet electrolytic capacitor of claim 1, wherein the substrate comprises a metal selected from the group consisting of tantalum, niobium, aluminum, nickel, hafnium, titanium, copper, silver, and combinations thereof.

19. The wet electrolytic capacitor of claim 1, wherein the electrolyte is an aqueous solution containing an acid.

20. The wet electrolytic capacitor of claim 1, wherein the anode comprises tantalum or niobium.

21. The wet electrolytic capacitor of claim 20, wherein the anode comprises niobium oxide.

22. A method for forming a wet electrolytic capacitor, the method comprising:

applying a plurality of metal particles to a substrate of a cathode, wherein the metal particles have a median size of from about 20 to about 500 micrometers;

sintering the metal particles;

applying a coating formulation to the substrate after sintering the metal particles, the coating formulation comprising electrochemically-active particles; and

disposing an electrolyte between the cathode and an anode.

23. The method of claim 22, wherein the metal particles are sintered at a temperature of from about 1000°

C. to about 2000°

C.

24. The method of claim 22, wherein the metal particles are sintered at a temperature of from about 1200°

C. to about 1800°

C.

25. The method of claim 22, wherein the metal particles are sintered at a pressure of less than about 50 millitorr.

26. The method of claim 22, wherein the metal particles comprise tantalum.

27. The method of claim 22, wherein the metal particles have a median size of from about 50 to about 200 micrometers.

28. The method of claim 22, wherein the metal particles are agglomerated.

29. The method of claim 22, further comprising pre-coating the substrate with a viscous liquid prior to application of the metal particles.

30. The method of claim 22, wherein the coating formulation is sintered at a temperature of from about 500°

C. to about 2400°

C.

31. The method of claim 22, wherein the electrochemically-active particles comprise carbon.

32. The method of claim 22, wherein the electrochemically-active particles comprise a metal.

33. The method of claim 22, wherein the electrochemically-active particles comprise a metal oxide.

34. The method of claim 33, wherein the metal oxide is RuO₂.