Capacitor containing aluminum anode foil anodized in low water content glycerine-phosphate electrolyte without a pre-anodizing hydration step
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 - 4 . (canceled)
5 . A process for preparing a capacitor comprising:
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 process for preparing a capacitor of claim 5 wherein said voltage is applied in increasing increments with an age time between each said increment.
7 . The process for preparing a capacitor of claim 6 wherein said increments are less than about 75 volts.
8 . The process for preparing a capacitor of claim 7 wherein said increments are at least about 20 V to no more than about 50 V.
9 . The process for preparing a capacitor of claim 6 wherein said age time is sufficient for the current to decrease to from about 1 to about 50% of an initial current.
10 . The process for preparing a capacitor of claim 9 wherein said age time is sufficient for the current to decrease to from about 10 to about 30% of said initial current.
11 . The process for preparing a capacitor of claim 10 wherein said age time is sufficient for the current to decrease to about 20% of said initial current.
12 . The process for preparing a capacitor of claim 5 wherein said anodizing solution is at a temperature of about 25° C. to about 125° C.
13 . The process for preparing a capacitor of claim 12 wherein said anodizing solution is at a temperature of about 80° C. to about 105° C.
14 . The process for forming a capacitor of claim 5 wherein said anodizing solution comprises about 0.01 to about 0.1% soluble orthophosphate.
15 . The process for forming a capacitor of claim 5 wherein said soluble orthophosphate is selected from a group consisting of ammonium phosphate, alkali metal phosphate, amine phosphate and mixtures thereof.
16 . The process for forming a capacitor of claim 5 wherein said soluble orthophosphate is selected from a group consisting of mono-sodium phosphate, di-potassium phosphate, and sodium potassium phosphate.
17 . The process for forming a capacitor of claim 5 wherein said soluble orthophosphate is selected from a group consisting of mono-ammonium phosphate and di-ammonium phosphate.
18 . The process of claim 5 wherein said anodising solution comprises about 0.1 to about 1%, by weight, water.
19 - 22 . (canceled)
23 . A process for preparing a capacitor comprising:
forming an aluminum plate;
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.
24 . The process for preparing a capacitor of claim 23 wherein said final voltage is above 220 volts.
25 . The process for preparing a capacitor of claim 24 wherein said voltage is increased by no more than about 75 volts.
26 . The process for preparing a capacitor of claim 25 wherein said voltage is increased by at least about 20 V to no more than about 50 V.
27 . The process for preparing a capacitor of claim 23 wherein said first measured current or said second measured current is from about 1 to about 50% of said initial current.
28 . The process for preparing a capacitor of claim 27 wherein said first measured current or said second measured current is from about 10 to about 30% of said initial current.
29 . The process for preparing a capacitor of claim 28 wherein said first measured current or said second measured current is about 20% of said initial current.
30 . The process for preparing a capacitor of claim 23 wherein said anodizing solution is at a temperature of about 25° C. to about 125° C.
31 . The process for preparing a capacitor of claim 30 wherein said anodizing solution is at a temperature of about 80° C. to about 105° C.
32 . The process for forming a capacitor of claim 23 wherein said anodizing solution comprises about 0.01 to about 0.1% soluble orthophosphate.
33 . The process for forming a capacitor of claim 23 wherein said soluble orthophosphate is selected from a group consisting of ammonium phosphate, alkali metal phosphate, amine phosphate and mixtures thereof.
34 . The process for forming a capacitor of claim 23 wherein said soluble orthophosphate is selected from a group consisting of mono-sodium phosphate, di-potassium phosphate, and sodium potassium phosphate.
35 . The process for forming a capacitor of claim 23 wherein said soluble orthophosphate is selected from a group consisting of mono-ammonium phosphate and di-ammonium phosphate.
36 - 40 . (canceled)