Conductive Polymer Electrolytic Capacitor With Controlled Water Content
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Solution Overview
Problem
Conventional electrolytic capacitors with carbon-containing layers in the cathode fail to achieve sufficient restoring properties of the dielectric layer when combined with an electrolyte solution, leading to increased leakage current and ESR, and insufficient adhesion between the cathode and conductive layers.
Innovation Solution
An electrolytic capacitor design featuring a conductive polymer layer interposed between the anode and cathode foils, with a carbon layer on the cathode foil, and an electrolyte solution with a water content between 0.1% to 6.0% by mass, formed using a dispersion or solution containing conductive polymer, to enhance capacitance and reduce ESR while maintaining adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a carbon-containing layer is formed on the cathode foil to increase capacitance, then the capacitance is improved, but the adhesion between the cathode and conductive layer becomes insufficient
Solution Approach 1:
An interposing layer including aluminum carbide is introduced between the aluminum cathode foil and the carbon-containing layer. This intermediary layer serves as a bonding bridge that chemically bonds to both the aluminum substrate and the carbon layer, thereby ensuring sufficient adhesion while maintaining the high capacitance provided by the carbon-containing layer.
Solution Approach 2:
The cathode structure is designed as a composite system consisting of multiple layers: the aluminum cathode foil, the aluminum carbide interposing layer, and the carbon-containing layer. This composite structure combines the high conductivity and capacitance of carbon materials with the strong bonding capability of aluminum carbide, achieving both high capacitance and sufficient adhesion.
2Device complexity
If conventional electrolyte solutions are used with carbon-containing layers, then the capacitor structure is simple, but the restoring properties of the dielectric layer are insufficient, leading to increased leakage current and ESR
Solution Approach 1:
The chemical composition parameters of the electrolyte solution are optimized by specifying precise proportions of boric acid (0.01-5 wt%), boric acid esters (5-40 wt%), and water (55-95 wt%). This parameter optimization enables the electrolyte to effectively restore the dielectric layer, reducing leakage current and ESR while maintaining a relatively simple overall capacitor structure.
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 proposed design secures high capacitance, suppresses ESR, and reduces leakage current, maintaining adhesion and stability over time by optimizing the water content in the electrolyte solution and using a conductive polymer layer with a carbon layer.
Implementation Method 1
a conductive polymer layer that is interposed between the anode foil and the cathode foil, the conductive polymer layer including a conductive polymer. The conductive polymer layer is a layer formed with use of a dispersion or a solution containing the conductive polymer
Implementation Method 2
A conductive layer provided with a carbon layer including conductive carbon is formed on the cathode foil
Implementation Method 3
a proportion of water (water content) in the electrolyte solution ranges from 0.1% by mass to 6.0% by mass, inclusive
Data Source
AI summary
An electrolytic capacitor includes a capacitor element and an electrolyte solution. The capacitor element includes: an anode foil on which a dielectric layer is formed; a cathode foil which is opposite to the anode foil; and a conductive polymer layer that is interposed between the anode foil and the cathode foil, conductive polymer layer including a conductive polymer. A conductive layer provided with a carbon layer including conductive carbon is formed on the cathode foil. The conductive polymer layer is a layer formed with use of a dispersion or a solution containing the conductive polymer. And a proportion of water in the electrolyte solution ranges from 0.1% by mass to 6.0% by mass, inclusive.