Method of producing an aluminum slug anode
An aluminum slug anode usable in capacitors is produced from multiple-stacked layers of aluminum foils. The foils are stacked (possibly after cutting them to have an area similar to the area desired for the anode), hot-pressed, sintered, and anodized to generate the anode. A contact in electrical communication with the foils is formed, as by welding a contact across at least some of the foils. A capacitor casing be formed by situating the anode within a casing which serves as a cathode, with the anode being wrapped in a dielectric such as separator paper.
1. A method of producing an aluminum slug anode for a capacitor, the method including the steps of:
a. stacking etched aluminum foils into a multi-layer stack,
b. hot pressing the multi-layer stack of aluminum foils,
c. sintering the pressed multi-layer stack of aluminum foils, and
d. anodizing the multi-layer stack of joined aluminum foils.
2. The method of claim 1 further including the step of cutting the aluminum foils to a desired area, whereby the anodized multi-layer stack of joined aluminum foils has at least substantially the desired area.
3. The method of claim 2 wherein the cutting step occurs prior to one or more of the pressing and sintering steps.
4. The method of claim 2 wherein the cutting step occurs after the sintering step.
5. The method of claim 1 wherein the hot pressing step occurs at a temperature between 350° C. and 500° C.
6. The method of claim 5 wherein the hot pressing step is performed for 1 to 10 minutes.
7. The method of claim 5 wherein the hot pressing step is performed for 2 to 3 minutes.
8. The method of claim 1 wherein the hot pressing step occurs at a temperature between 390° C. and 410° C.
9. The method of claim 1 wherein the hot pressing step occurs at a pressure between 20 MPa and 40 Mpa.
10. The method of claim 1 wherein the hot pressing step occurs at a pressure between 25 MPa and 30 MPa.
11. The method of claim 1 wherein the sintering step occurs at a temperature between 575° C. and 650° C.
12. The method of claim 11 wherein the sintering step is performed between 30 minutes and 2 hours, preferably between 40 minutes and 1 hour.
13. The method of claim 11 wherein the sintering step is performed between 40 minutes and 1 hour.
14. The method of claim 1 wherein the sintering step occurs at a temperature between 620° C. and 635° C.
15. The method of claim 1 wherein the sintering step is performed in a reducing atmosphere.
16. The method of claim 1 wherein the sintering step is performed in a primarily hydrogen atmosphere.
17. The method of claim 1 wherein at least one of the hot pressing step and the sintering step is performed in an atmosphere primarily formed of:
a. hydrogen, or
b. a forming gas.
18. The method of claim 1 wherein the hot pressing step is performed in a reducing atmosphere.
19. The method of claim 1 wherein the step of anodizing the multi-layer stack of joined aluminum foils includes exposing the foils to a solution of boric acid and ammonium water to form an aluminum oxide layer.
20. The method of claim 1 wherein the anodized multi-layer stack of joined aluminum foils has an effective surface area between 4000 cm2/cc to 9000 cm2/cc.
21. The method of claim 1 wherein the anodized multi-layer stack of joined aluminum foils has an effective surface area between 4400 cm2/cc to 8900 cm2/cc.
22. The method of claim 1 further including the step of forming a contact in electrical communication with the aluminum foils within the multi-layer stack.
23. The method of claim 22 wherein the contact is formed by welding together aluminum foils within the multi-layer stack.
24. The method of claim 1 further including the step of electrochemically etching aluminum foils, thereby forming the etched aluminum foils.
25. The method of claim 1 further including the steps of:
a. situating the anodized multi-layer stack of joined aluminum foils within the interior of a casing, with a contact in electrical communication with the joined aluminum foils being exposed from the exterior of the casing;
b. filling the interior of the casing with electrolyte, and
c. sealing the casing about the joined aluminum foils and electrolyte.
26. The method of claim 25 wherein the anodized multi-layer stack of joined aluminum foils is at least partially surrounded by separator paper within the casing.
27. The method of claim 25 wherein the anodized multi-layer stack of joined aluminum foils is at least partially surrounded by foil within the casing.
28. A capacitor including one or more anodized multi-layer stacks of joined aluminum foils formed by the method of claim 1 .
29. An implantable medical device including one or more of the capacitors of claim 28 .
30. The implantable medical device of claim 29 wherein the implantable medical device includes one or more of:
a. a cardioverter, and
b. a defibrillator.