Avx Corporation

Dirk H Dreissig

John L Galvagni

Martin Biler

Jan Petrzilek

Bharat Rawal

Mitchell D Weaver

Andrew Paul Ritter

Zebbie Lynn Sebald

James Steven Bates

Frantisek Priban

Lee Shinaberger

Jessica M Smith

Gang Ning

Jonathan Robert Knopsnyder

Tomas Karnik

David Masheder

Ian Pinwill

Robert Hazen Pease

Bob Knopsnyder

Richard Baker

A wet electrolytic capacitor is provided. The capacitor contains an anode comprising an anodically oxidized pellet formed from a pressed and sintered powder, a cathode that contains a metal substrate coated with a conductive polymer, and a working electrolyte in communication with the anode and the cathode. The working electrolyte is in the form of a gel and comprises an ammonium salt of an organic acid, inorganic oxide particles, an acid, and a solvent system that comprises water. The working electrolyte has a pH value of from about 5.0 to about 8.0.

Wet electrolytic capacitor containing a gelled working electrolyte

A wet electrolytic capacitor that contains an anodically oxidized porous anode body, a cathode containing a metal substrate coated with a conductive coating, and a working electrolyte that wets the dielectric on the anode. The conductive coating is formed through anodic electrochemical polymerization ('electro-polymerization') of a precursor colloidal suspension on the surface of the substrate. The colloidal suspension includes a precursor monomer, ionic surfactant, and sulfonic acid, which when employed in combination can synergistically improve the degree of surface coverage and overall conductivity of the coating.

Wet capacitor cathode containing a conductive coating formed anodic electrochemical polymerization of a colloidal suspension

A wet electrolytic capacitor that contains an anodically oxidized porous anode body, a cathode containing a metal substrate coated with a conductive coating, and a working electrolyte that wets the dielectric on the anode. The conductive coating contains a conductive copolymer having at least one thiophene repeating unit, as well as a pyrrole repeating unit and/or aniline repeating unit.

Wet capacitor cathode containing a conductive copolymer

A wet electrolytic capacitor including a porous anode body containing a dielectric layer, a cathode containing a metal substrate on which is disposed a conductive polymer coating, and an electrolyte is provided. The conductive polymer coating is in the form of a dispersion of particles having an average diameter of from about 1 to about 500 nanometers, in some embodiments from about 5 to about 400 nanometers, and in some embodiments, from about 10 to about 300 nanometers. The relatively small size of the particles used in the coating increases the surface area that is available for adhering to the metal substrate, which in turn improves mechanical robustness and electrical performance (e.g., reduced equivalent series resistance and leakage current). Another benefit of employing such a dispersion for the conductive polymer coating is that it may be able to better cover crevices of the metal substrate and improve electrical contact.

Conductive polymer coating for wet electrolytic capacitor

A wet electrolytic capacitor that includes a porous anode body containing a dielectric layer, an electrolyte, and a cathode containing a metal substrate that is abrasive blasted is provided. Abrasive blasting may accomplish a variety of different purposes. For example, it may result in a surface that is substantially uniform and macroscopically smooth, thereby increasing the consistency of conductive coatings formed thereon. While possessing a certain degree of smoothness, the abrasive blasted surface is nevertheless micro-roughened so that it contains a plurality of pits. The pits provide an increased surface area, thereby allowing for increased cathode capacitance for a given size and/or capacitors with a reduced size for a given capacitance. A conductive coating that contains a substituted polythiophene is disposed on the micro-roughened surface. The presence of the pits on the substrate enhances the degree of contact between the conductive coating and metal substrate, thereby resulting in improved mechanical robustness and electrical performance (e.g., reduced equivalent series resistance and leakage current).

Abrasive blasted conductive polymer cathode for use in a wet electrolytic capacitor

A wet electrolytic capacitor that contains a sintered anode positioned with an interior space of a metal casing is provided. The anode and metal casing are of a size such that the anode occupies a substantial portion of the volume of the interior space. More particularly, the anode typically occupies about 70 vol. % or more, in some embodiments about 75 vol. % or more, in some embodiments from about 80 vol. % to about 98 vol. %, and in some embodiments, from about 85 vol. % to 95 vol. % of the interior space. Among other things, the use of an anode that occupies such a large portion of the interior space enhances volumetric efficiency and other electrical properties of the resulting capacitor.

Volumetrically efficient wet electrolytic capacitor

A wet electrolytic capacitor that includes a porous anode body that contains a dielectric layer formed by anodic oxidation; a cathode that includes a metal substrate coated with a conductive polymer; and an aqueous electrolyte disposed in contact with the cathode and the anode is provided. The electrolyte includes a salt of a weak organic acid and water. The electrolyte has a pH of from about 5.0 to about 8.0 and an ionic conductivity of from about 0.5 to about 80 milliSiemens per centimeter or more, determined at a temperature of 25&#xb0; C.

High voltage electrolytic capacitors

A capacitor containing an electrochemical cell that includes ruthenium oxide electrodes and an aqueous electrolyte containing a polyprotic acid (e.g., sulfuric acid) is provided. More specifically, the electrodes each contain a substrate that is coated with a metal oxide film formed from a combination of ruthenium oxide and inorganic oxide particles (e.g., alumina, silica, etc.). Without intending to be limited by theory, it is believed that the inorganic oxide particles may enhance proton transfer (e.g., proton generation) in the aqueous electrolyte to form hydrated inorganic oxide complexes (e.g., [Al(HO)] to [Al(HO)(OH)]). The inorganic oxide thus acts as a catalyst to both absorb and reversibly cleave water into protons and molecular bonded hydroxyl bridges. Because the anions (e.g., sulfate and bisulfate ions) in the electrolyte are not bound in the coordination sphere of the formed aqua complexes, they do not impede the condensation of these complexes required to achieve the additional capacitance over the potential range. As a result, the ionic charges are kept separate and the chemical process may generate pseudo-capacitance. This, in turn, may result in an increase in the charge density and capacitance of the electrode.

Electrochemical capacitor containing ruthenium oxide electrodes

An electric double layer capacitor that contains at least one electrochemical cell is provided. The cell contains electrodes (e.g., two electrodes) that each contain a porous matrix of electrochemically-active particles (e.g., carbon). An aqueous-based electrolyte is disposed in contact with the porous matrix. In accordance with the present invention, the electrolyte is provided with an anionic polymer that serves as binding agent for the electrochemically active particles and thus reduces electrolyte loss, especially at higher temperatures. Because the polymer is anionic in nature, it is generally hydrophilic and thus can retain its binding properties in the presence of water. The anionic nature of the polymer also allows it to remain stable in the presence of a corrosive polyprotic acid, which is employed in the electrolyte to enhance charge density. Thus, as a result of the present invention, a capacitor may be formed that is capable of exhibiting good electrical performance (e.g., high capacitance and low ESR), even at high temperatures (e.g., 70&#xb0; C. and above).

Electric double layer capacitor

A cathode containing a metal substrate that possesses a micro-roughened surface imparted by spark anodization is provided. The surface is formed by contacting the substrate with an electrolytic solution and applying a voltage to form a dielectric sub-oxide layer. The voltage is raised to a sufficiently high level to initiate 'sparking' at the surface of the substrate, which is believed to create high local surface temperatures sufficient to etch away the substrate. This results in the formation of a 'micro-roughened' surface having a plurality elevated regions. These elevated regions can increase the effective surface area and thus allow for the formation of capacitors with increased cathode capacitance for a given size and/or capacitors with a reduced size for a given capacitance. The elevated regions may also exhibit excellent adhesion to additional electrochemically-active materials and provide enhanced stability in certain liquid electrolytes.

Cathode for use in a wet capacitor

An electrolytic capacitor that contains an anodically oxidized porous anode, cathode, and an electrolyte that contains an alkali metal salt and ionically conductive polymer is provided. The alkali metal salt forms a complex with the ionically conductive polymer and thereby improves its ionic conductivity, particularly at higher temperatures. The electrolyte also contains an organic solvent that reduces the viscosity of the electrolyte and helps lower the potential barrier to metal ion transport within the electrolyte to improve conductivity. By selectively controlling the relative amount of each of these components, the present inventors have discovered that a highly ionically conductive electrolyte may be formed that is also in the form of a viscous liquid. The liquid nature of the electrolyte enables it to more readily enter the pores of the anode via capillary forces and improve specific capacitance. Further, although a liquid, its viscous nature may inhibit the likelihood of leakage.

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Myrtle Beach, SC, United States of America

Dirk H Dreissig