Cathode Foil Carbon Interface for Stable Electrolytic Capacitance
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Solution Overview
Problem
The deposition process of metal nitrides is complex and costly, and electrolytic capacitors with porous carbon layers on the cathode foil exhibit lower capacitance at normal and high temperatures compared to those with metal nitride deposits.
Innovation Solution
An electrode body with a cathode foil featuring an enlarged surface layer and a carbon layer that penetrates etching pits, forming an uneven interface with a specific depth and structure, enhancing capacitance and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous carbon layer containing activated carbon is formed on the cathode foil by applying paste, then the cathode side capacitance is emerged by electric double layer storage action, but the capacitance in normal temperature environment and high temperature environment is lower compared to metal nitride deposition
Solution Approach 1:
The patent utilizes a porous carbon layer containing activated carbon to form the cathode structure. The porous structure enables electric double layer storage action, which is the mechanism for achieving capacitance on the cathode side. This principle directly addresses the technical challenge of creating a functional cathode with sufficient capacitance while avoiding complex metal nitride deposition processes.
2Reliability
If the surface area of the cathode foil is increased by etching treatment, then the capacitance is improved, but the enlargement is limited from the viewpoint of the thickness of the cathode foil
Solution Approach 1:
The patent forms an enlarged surface layer with a specific uneven shape having convex and concave portions, creating a three-dimensional surface structure. This dimensional transformation allows the cathode to achieve increased effective surface area for capacitance without proportionally increasing the overall thickness of the cathode foil, thus resolving the contradiction between capacitance enhancement and thickness limitation.
Solution Approach 2:
The porous carbon layer is formed within the concave portions of the uneven surface structure, utilizing the three-dimensional space created by the enlarged surface layer. This allows the carbon layer to be positioned in the recesses, effectively increasing the electroactive surface area without adding significant thickness to the overall cathode structure.
3Reliability
If an interface between the enlarged surface layer and the carbon layer has an uneven shape with specific depth, then the capacitance deterioration at high temperatures and high frequencies is reduced, but the manufacturing precision requirements are increased
Solution Approach 1:
The enlarged surface layer with its uneven shape is formed prior to applying the porous carbon layer. This preliminary creation of the three-dimensional surface structure provides a template that guides the subsequent carbon layer formation, ensuring that the carbon fills the concave portions and creates the desired interface morphology. This sequential approach helps achieve the required interface precision while managing manufacturing complexity.
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 improved capacitance and reduced capacitance deterioration at high temperatures and high frequencies, outperforming capacitors with titanium nitride deposits in thermal stability and capacitance performance.
Implementation Method 1
a carbon layer which is formed on the enlarged surface layer, wherein an interface between the enlarged surface layer and the carbon layer has an uneven shape
Implementation Method 2
The electrolytic solution is in close contact with the uneven surface of the anode foil and functions as a true cathode. In this electrolytic capacitor, a capacitance on the anode side is obtained by a dielectric polarization action of the dielectric oxide film layer
Implementation Method 3
a capacitance on the anode side is obtained by a dielectric polarization action of the dielectric oxide film layer
Implementation Method 4
The anode foil is enlarged by forming the valve acting metal into a shape such as a sintered body or an etching foil, and has a dielectric oxide film layer on the enlarged surface
Data Source
AI summary
Provided is an electrode body that exhibits a good cathode side capacitance, and an electrolytic capacitor provided with this electrode body. The electrode body used for a cathode of the electrolytic capacitor has a cathode foil and a carbon layer. The cathode foil is made of a valve acting metal, and an enlarged surface layer is formed on the surface thereof. The carbon layer is formed on the enlarged surface layer. The interface between the enlarged surface layer and the carbon layer has an uneven shape.