Cathode Foil Carbon Interface for High-Temperature ESR Stability
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Solution Overview
Problem
Electrolytic capacitors with solid electrolytes experience a significant increase in Equivalent Series Resistance (ESR) under high-temperature environments due to the formation of an oxide film on the cathode foil, which is exacerbated by moisture interaction.
Innovation Solution
The electrolytic capacitor design includes a carbon layer laminated on the cathode foil with an interfacial resistance of 1.1 mΩ·cm2 or less, achieved through pressure-welding and forming an enlarged surface layer on the cathode foil to enhance adhesion, thereby reducing moisture contact and suppressing oxide film growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a carbon layer is formed on the cathode foil to reduce ESR, then the adhesion between the carbon layer and conductive polymer is improved, but the oxide film gradually grows on the surface of the metal carbide or cathode foil, increasing ESR under high-temperature conditions
Solution Approach 1:
The patent introduces a metal carbide layer as an intermediary between the cathode foil and the carbon layer. This intermediate layer acts as a barrier that prevents direct contact between moisture and the cathode foil, thereby suppressing oxide film growth while maintaining low ESR through excellent adhesion properties of the carbon layer
2Reliability
If the interfacial resistance between cathode foil and carbon layer is reduced to minimize ESR, then the capacitor performance is improved, but moisture can more easily contact the cathode foil and promote oxide film formation
Solution Approach 1:
The metal carbide layer serves as a protective intermediary that decouples the relationship between low interfacial resistance and moisture contact. It allows the carbon layer to maintain excellent electrical contact with the cathode foil for low ESR while simultaneously blocking moisture from reaching the cathode foil surface
3Productivity
If a solid electrolyte is used instead of electrolytic solution, then the capacitor becomes compact with large capacity and low ESR, but the ability to repair defects in the dielectric oxide film is reduced
Solution Approach 1:
The patent merges the advantages of both solid and liquid electrolytes by combining a solid electrolyte layer with a hybrid structure that includes a metal carbide layer and carbon layer. This composite structure maintains the compactness and low ESR of solid electrolytes while the metal carbide layer provides protective functions that enhance overall 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 effectively suppresses the increase in ESR under high-temperature conditions, maintaining capacitor performance by minimizing interfacial resistance and oxide film formation.
Implementation Method 1
the carbon layer is laminated on the cathode foil with an interfacial resistance of 1.1 mΩ·cm2 or less, achieved through pressure-welding
Implementation Method 2
forming an enlarged surface layer on the cathode foil to enhance adhesion
Implementation Method 3
the oxide film is formed on the cathode foil by the hydration between the cathode foil and the moisture
Data Source
AI summary
The present disclosure provides an electrolytic capacitor in which an increase in the ESR is suppressed even in the high-temperature environment, a cathode body in the electrolytic capacitor, and a manufacturing method of the electrolytic capacitor. The electrolytic capacitor includes an anode foil, a cathode body, and electrolytic solution. The anode foil is formed of valve metal and has dielectric oxide film on a surface of the foil. The cathode body includes cathode foil formed of valve metal and a carbon layer laminated on the cathode foil. An interfacial resistance between the cathode foil and the carbon layer is 1.1 mΩ·cm2 or less.