Abrasive Blasted Conductive Polymer Cathode for Wet Electrolytic Capacitors

Solution Overview

Problem

Wet electrolytic capacitors face challenges with mechanical robustness and electrical performance due to detachment of conventional coatings in the presence of aqueous electrolytes, limiting their high-voltage applications.

Innovation Solution

A method involving abrasive blasting to create a micro-roughened surface on a metal substrate, followed by applying a conductive coating of intrinsically conductive substituted polythiophene, enhancing adhesion and increasing surface area for improved capacitance and mechanical robustness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional coatings (activated carbon, metal oxides) are used on the cathode substrate, then high capacitance can be achieved, but the coatings become easily detached under certain conditions such as in the presence of aqueous electrolytes

Engineering Contradiction:

ImprovecapacitanceVSAvoidcoating adhesion

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The cathode substrate is prepared with a micro-roughened surface containing a plurality of pits through abrasive blasting. This porous surface structure increases the surface area for capacitance while providing mechanical interlocking for the conductive polymer coating, preventing detachment in aqueous electrolytes.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The invention uses a composite structure combining the metal substrate with intrinsically conductive substituted polythiophene coating. This composite material provides both the mechanical robustness of the metal substrate and the high capacitance of the conductive polymer, while the polythiophene's inherent conductivity eliminates the need for conventional coatings that detach easily.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If the cathode uses a smooth surface, then the manufacturing process is simpler, but the surface area is reduced leading to lower capacitance

Engineering Contradiction:

Improvesurface preparation simplicityVSAvoidcapacitance

Core Design Contradiction:

Ease of manufactureVSQuantity of substance

Solution Approach 1:

The cathode substrate is prepared with a micro-roughened surface containing a plurality of pits through abrasive blasting. This porous surface structure increases the surface area for capacitance while providing mechanical interlocking for the conductive polymer coating, preventing detachment in aqueous electrolytes.

Inventive Principle:

Principle #31Porous materials

3Quantity of substance

If conventional coatings are used, then high capacitance can be achieved, but the equivalent series resistance and leakage current increase, limiting high-voltage applications

Engineering Contradiction:

ImprovecapacitanceVSAvoidequivalent series resistance and leakage current

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The invention uses a composite structure combining the metal substrate with intrinsically conductive substituted polythiophene coating. This composite material provides both the mechanical robustness of the metal substrate and the high capacitance of the conductive polymer, while the polythiophene's inherent conductivity eliminates the need for conventional coatings that detach easily.

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The approach results in enhanced mechanical robustness and electrical performance, including reduced equivalent series resistance and leakage current, making the capacitors suitable for high-voltage applications without the need for conventional coatings like activated carbon or metal oxides.

Implementation Method 1

propelling an abrasive media against a metal substrate to form a micro-roughened surface that contains a plurality of pits

Methodology Applied

Scientific EffectAbrasion: Abrasion

Implementation Method 2

A conductive coating is formed on the micro-roughened surface that comprises an intrinsically conductive substituted polythiophene

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Implementation Method 3

a dielectric metal oxide film over the anode surface

Methodology Applied

Scientific EffectAnodic oxidation: Anodising

Data Source

PatentUS8605411B2Abrasive blasted conductive polymer cathode for use in a wet electrolytic capacitor

Publication Date: 2013.12.10 KYOCERA AVX COMPONENTS CORP

AI summary

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).