Electrolytic Capacitor Cathode Adhesion via Inorganic Projections
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Solution Overview
Problem
Conventional electrolytic capacitors with carbon-containing layers and electrolyte solutions face challenges in achieving high capacitance while maintaining low equivalent series resistance (ESR) and leakage current, due to insufficient adhesion and restoration properties of the carbon-containing layer.
Innovation Solution
The electrolytic capacitor design includes a conductive polymer layer between an anode and cathode foils, with an inorganic layer on the cathode foil featuring projections and recesses to enhance adhesion and a controlled water proportion in the electrolyte solution to reduce ESR and leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a carbon-containing layer is used in the cathode, then capacitance can be increased, but adhesion between the carbon-containing layer and aluminum is insufficient
Solution Approach 1:
The patent applies composite materials by creating a multi-layer cathode structure consisting of an aluminum foil base layer, an intermediate aluminum carbide layer, and a carbon-containing layer. This composite structure combines the advantages of each material: aluminum provides structural support and electrical conductivity, aluminum carbide provides strong adhesion and serves as a bonding interface, and the carbon-containing layer provides high capacitance. The intermediate aluminum carbide layer acts as a transition zone that chemically bonds with both the aluminum substrate and the carbon layer, solving the adhesion problem while maintaining high capacitance.
2Reliability
If electrolyte solution is added to restore dielectric layer, then leakage current can be reduced, but ESR increases and capacitance decreases
Solution Approach 1:
The patent applies local quality by creating a spatially differentiated structure where the cathode foil surface is selectively modified. The intermediate aluminum carbide layer is formed only at specific locations on the cathode foil surface through localized treatment, creating regions with different properties. This allows the carbon-containing layer to adhere strongly at treated locations while maintaining overall capacitance. The localized modification enables the system to achieve both low leakage current (through proper electrolyte interaction) and high capacitance (through adequate carbon layer coverage) without the trade-off present in uniform treatment approaches.
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
This configuration secures high capacitance and low ESR while suppressing leakage current, maintaining performance over time by optimizing the adhesion between the conductive polymer and inorganic layers and managing the water content in the electrolyte solution.
Implementation Method 1
The inorganic layer has a surface having projections and recesses. The projections form a region where the inorganic layer is in contact with the conductive polymer layer
Implementation Method 2
The conductive polymer layer includes a conductive polymer
Implementation Method 3
A dielectric layer is formed on the anode foil
Implementation Method 4
A proportion of water 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, a cathode foil opposite to the anode foil, and a conductive polymer layer disposed between the anode foil and the cathode foil. A dielectric layer is formed on the anode foil. An inorganic layer is formed on the cathode foil. The conductive polymer layer includes a conductive polymer. The inorganic layer has a surface having projections and recesses. The projections form a region where the inorganic layer is in contact with the conductive polymer layer and the recesses form a region where the inorganic layer is not in contact with the conductive polymer layer. A proportion of water in the electrolyte solution ranges from 0.1% by mass to 6.0% by mass, inclusive.