Directionally-grown capacitor anodes
First Claim
1. A capacitor comprising:
- an anode which includes a directionally grown sponge having a high surface area, the sponge defining dendrites having a width of less than about 30 micrometers;
a dielectric film on a surface of the sponge; and
, a cathode which includes an electrolyte in contact with the dielectric film.
2 Assignments
0 Petitions
Accused Products
Abstract
A dendritic sponge which is directionally-grown on a substrate material has a high surface to volume ratio and is suitable for forming anodes for highly efficient capacitors. A dielectric film is formed on the sponge surface by oxidizing the surface. In a preferred embodiment, the dielectric is grown on titanium sponge and is doped with oxides of Ca, Mg, Sr, Be, or Ba to improve the film'"'"'s dielectric constant or with higher valent cations, such as Cr6+, V5+, Ta5+, Mo6+, Nb5+, W6+, and P5+, to reduce the oxygen vacancy concentration and leakage current of the dielectric film. A capacitor formed from the sponge includes a cathode electrolyte which serves as an electrical conductor and to repair the dielectric film by re-oxidizing the anode surface at areas of local breakdown. Sponges of titanium, tantalum, and aluminum form efficient dielectric films. In another embodiment, sponges of elements which do not form efficient dielectric films are coated with a dielectric material. Capacitors formed with titanium sponges have energy densities of 10−2 to 50 Watt hours and power densities of 100,000 to 10,000,000 Watts per kilogram of titanium.
47 Citations
41 Claims
-
1. A capacitor comprising:
-
an anode which includes a directionally grown sponge having a high surface area, the sponge defining dendrites having a width of less than about 30 micrometers;
a dielectric film on a surface of the sponge; and
,a cathode which includes an electrolyte in contact with the dielectric film. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 12, 15, 16, 17, 18, 19, 31)
-
-
10. A capacitor, comprising:
-
an anode which includes a directionally grown sponge having a high surface area, the anode including a plurality of substrate layers, the dendrites extending from the substrate;
a dielectric film on a surface of the sponge; and
a cathode which includes an electrolyte in contact with the dielectric film. - View Dependent Claims (11)
-
-
13. A capacitor comprising:
-
an anode which includes a directionally grown sponge having a high surface area, the anode including at least one substrate layer, the substrate layer being formed from a material which is the same as that of the sponge, the dendrites extending from the substrate layer;
a dielectric film on a surface of the sponge; and
a cathode which includes an electrolyte in contact with the dielectric film. - View Dependent Claims (14)
-
-
20. A capacitor comprising:
-
an anode which includes a directionally grown sponge having a high surface area;
a dielectric film on a surface of the sponge, the dielectric film including a dopant selected from the group consisting of oxides of Ba, Ca, Mg, Sr, Be, and combinations thereof; and
a cathode which includes an electrolyte in contact with the dielectric film.
-
-
21. A capacitor comprising:
-
an anode which includes a directionally grown sponge having a high surface area;
a dielectric film on a surface of the sponge, the dielectric film including;
an oxide formed by oxidizing the surface of the sponge, and a low concentration of one or more cations having a higher valency than that of the oxide; and
a cathode which includes an electrolyte in contact with the dielectric film. - View Dependent Claims (22, 23)
-
-
24. A capacitor, comprising:
-
an anode which includes a directionally grown sponge having a high surface area;
a dielectric film on a surface of the sponge; and
a cathode which includes an electrolyte in contact with the dielectric film, the electrolyte including a low-melting metal saturated with a source of oxygen selected from the group consisting of dissolved oxygen, oxygen rich compounds, and combinations thereof. - View Dependent Claims (25, 26, 27, 28, 29, 30)
-
- 32. A directionally grown sponge suitable for forming capacitor anodes, the sponge being formed by a method which includes thermally growing dendrites on a substrate, the dendrites consisting essentially of an element selected from the group consisting of aluminum, antimony, arsenic, beryllium, bismuth, cadmium, chromium, cobalt, copper, gallium, germanium, hafnium, iron, lead, magnesium, manganese, nickel, niobium, selenium, silicon, silver, tantalum, tellurium, thallium, tin, titanium, vanadium, zinc, zirconium, and alloys thereof.
-
41. An anode adapted for use in a capacitor comprising a substrate having a plurality of metallic dendrites thereon, whereby said anode is characterized by its high surface area, the surface area being at least 10 cm2/gm.
Specification