Capacitor containing aluminum anode foil anodized in low water content glycerine-phosphate electrolyte without a pre-anodizing hydration step
View Patent ↗A capacitor comprising an aluminum anode and a dielectric layer comprising phosphate doped aluminum oxide and process for making the capacitor. The capacitor has a CV Product of at least 9 μF-V/cm 2 at 250 volts. Furthermore, the capacitor is formed by the process of: forming an aluminum plate; contacting the plate with an anodizing solution comprising glycerine, 0.1 to 1.0%, by weight, water and 0.01 to 0.5%, by weight, orthophosphate; applying a voltage to the aluminum plate and determining an initial current; maintaining the first voltage until a first measured current is no more than 50% of the initial current; increasing the voltage and redetermining the initial current; maintaining the increased voltage until a second measured current is no more than 50% of the redetermined initial current, and continuing the increasing of the voltage and maintaining the increased voltage until a final voltage is achieved.
1. A capacitor comprising:
an aluminum anode and a dielectric layer comprising phosphate doped aluminum oxide wherein said capacitor has a CV Product of at least 9 μF-V/cm 2 at 250 volts.
2. The capacitor of claim 1 wherein said capacitor has a CV Product of at least 10 μF-V/cm 2 at 250 volts.
3. The capacitor of claim 2 wherein said capacitor has a CV Product of at least 12 μF-V/cm 2 at 250 volts.
4. The capacitor of claim 1 wherein said phosphate is an orthophosphate.
5. A capacitor having a CV Product of at least 9 μF-V/cm 2 at 250 volts prepared by the process of:
forming an aluminum plate;
without pre-hydration, contacting said plate with an anodizing solution comprising glycerine, about 0.1 to about 2.0%, by weight, water and about 0.01 to about 0.5%, by weight, orthophosphate;
applying a voltage to said aluminum plate of at least about 220 volts.
6. The capacitor of claim 5 wherein said capacitor has a CV Product of at least 10 μF-V/cm 2 at 250 volts.
7. The capacitor of claim 6 wherein said capacitor has a CV Product of at least 12 μF-V/cm 2 at 250 volts.
8. A capacitor having a CV Product of at least 9 μF-V/cm 2 at 250 volts prepared by the process of:
forming an aluminum plate;
without pre-hydration contacting said plate with an anodizing solution comprising glycerine, about 0.1 to about 2.0%, by weight, water and about 0.01 to about 0.5%, by weight, orthophosphate;
applying a voltage to said aluminum plate and determining an initial current;
maintaining said first voltage until a first measured current is no more than 50% of said initial current;
increasing said voltage and redetermining said initial current;
maintaining said increased voltage until a second measured current is no more than about 50% of said redetermined initial current, and
continuing said increasing said voltage and said maintaining said increased voltage until a final voltage is achieved.
9. The capacitor of claim 8 wherein said capacitor has a CV Product of at least 10 μF-V/cm 2 at 250 volts.
10. The capacitor of claim 9 wherein said capacitor has a CV Product of at least 12 μF-V/cm 2 at 250 volts.
11. A capacitor comprising:
an aluminum anode and a dielectric layer comprising phosphate doped aluminum oxide wherein said capacitor has a CV Product of at least 9 μF-V/cm 2 at 250 volts;
prepared by the process of:
forming an aluminum plate;
without pre-hydration contacting said plate with an anodizing solution comprising glycerine, about 0.1 to about 2.0%, by weight, water and about 0.01 to about 0.5%, by weight, orthophosphate;
applying a voltage to said aluminum plate and determining an initial current;
maintaining said voltage until a first measured current is no more than about 50% of said initial current;
increasing said voltage and redetermining said initial current;
maintaining said increased voltage until a second measured current is no more than 50% of said redetermined initial current, and
continuing said increasing said voltage and said maintaining said increased voltage until a final voltage is achieved.