Electrolytic Capacitor Cathode Contact Resistance
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Solution Overview
Problem
Existing electrolytic capacitors face challenges in reliably expressing the redox capacity of conductive polymer layers due to insufficient electron supply, leading to limited capacity enhancement.
Innovation Solution
The electrolytic capacitor design features a cathode with a conductive substrate and a conductive polymer layer, where the contact resistance between the substrate and the polymer layer is maintained at 1 Ωcm² or less, ensuring reliable redox capacity expression by facilitating efficient electron transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the oxide film of the anode is made thick to improve dielectric breakdown voltage, then the dielectric breakdown voltage is improved, but the capacity of the electrolytic capacitor is lowered
Solution Approach 1:
The invention transitions from relying solely on oxide film thickness (one-dimensional approach) to utilizing the surface area expansion through fine particle coating (adding another dimension). By coating the anode with titanium fine particles having a specific surface area of 5 m²/g or more, the effective surface area increases dramatically, allowing capacity enhancement without increasing oxide film thickness, thus resolving the contradiction between dielectric breakdown voltage and capacity.
Solution Approach 2:
The invention employs porous or fine particle structures of titanium coating material with high specific surface area (5 m²/g or more). This porous/fine particle structure provides vastly increased surface area for charge storage while maintaining thin oxide film thickness, enabling simultaneous achievement of high dielectric breakdown voltage and high capacity.
2Quantity of substance
If chemical or electrochemical etching treatment is applied to increase surface area of valve metal foils, then the capacity is increased, but excessive etching causes dissolution of the aluminum foil surface, preventing further surface area increase
Solution Approach 1:
The invention introduces titanium fine particles as an intermediary coating layer between the aluminum foil and the electrolyte. This intermediary layer protects the aluminum foil from excessive dissolution while providing high surface area through the fine particle structure (specific surface area ≥5 m²/g), thus enabling capacity increase without compromising foil surface integrity.
Solution Approach 2:
The invention creates a composite structure combining aluminum foil substrate with titanium fine particle coating. This composite material leverages the electrical conductivity and structural stability of aluminum while adding the high surface area properties of titanium fine particles, achieving enhanced capacity without the detrimental effects of excessive etching.
3Quantity of substance
If a titanium vapor deposition film is formed on the surface of aluminum foil to increase surface area, then the capacity is increased, but at high temperatures the titanium film reacts with the electrolytic solution forming an oxide layer, significantly reducing capacity
Solution Approach 1:
The invention changes the critical parameter of specific surface area to ≥5 m²/g, which represents a fundamental shift from conventional thin film coatings. This parameter change enables the use of fine particle structures that maintain stability at high temperatures while providing sufficient surface area for high capacity, thus resolving the contradiction between capacity enhancement and high-temperature reliability.
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 design results in a significantly increased cathode capacity and capacity per unit volume of the electrolytic capacitor, with improved performance across a wide frequency range.
Implementation Method 1
the conductive polymer layer of the cathode that is in contact with the ion conductive electrolyte expresses a redox capacity when a voltage is applied between the anode and the cathode
Implementation Method 2
the contact resistance between the substrate and the polymer layer is maintained at 1 Ωcm² or less, ensuring reliable redox capacity expression by facilitating efficient electron transfer
Implementation Method 3
an ion conductive electrolyte filled in the space
Data Source
AI summary
Provided is an electrolytic capacitor that can reliably exhibit redox capacity due to a conductive polymer layer of a cathode. The electrolytic capacitor includes: a cathode having a conductive substrate and a conductive polymer layer placed on the surface of the conductive substrate; an anode having a substrate composed of a valve metal and a dielectric layer composed of an oxide of the valve metal that is placed on the surface of the substrate, the anode being disposed such that the dielectric layer and the conductive polymer layer of the cathode are opposed to each other across a space; and an ion conductive electrolyte with which the space is filled, the conductive polymer layer of the cathode that is in contact with the ion conductive electrolyte exhibiting a redox capacity due to application of a voltage between the anode and the cathode, wherein the contact resistance between the conductive substrate and the conductive polymer layer in the cathode is 1 Ωcm2 or less.