Electrolytic Capacitor Cathode Foil With Uneven Carbon Interface
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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 in normal and high temperature environments compared to those with metal nitride deposits.
Innovation Solution
An electrode body for electrolytic capacitors is developed, featuring a cathode foil with an enlarged surface layer and a carbon layer where the interface between the two has an uneven shape, allowing for enhanced capacitance and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a porous carbon layer containing activated carbon is formed on the cathode foil by applying paste, then the cathode structure is simplified and manufacturing is easier, but the capacitance in normal and high temperature environments is lower compared to metal nitride deposition
Solution Approach 1:
The invention changes the physical parameters of the carbon layer by controlling its thickness (0.1-10 μm) and forming an uneven interface with the enlarged surface layer. This parameter optimization allows the carbon layer to achieve both ease of manufacture and satisfactory capacitance performance, resolving the contradiction between manufacturing simplicity and electrical performance.
Solution Approach 2:
The invention introduces an uneven interface between the carbon layer and the enlarged surface layer, creating a curved rather than flat boundary. This curvature increases the effective surface area and improves capacitance while maintaining the simplicity of the paste application process, thus resolving the contradiction between ease of manufacture and capacitance performance.
2Reliability
If the surface area of the cathode foil is increased by etching treatment, then the capacitance is improved, but the thickness of the cathode foil is limited and further enlargement is difficult
Solution Approach 1:
The invention transitions from two-dimensional surface area enlargement through etching to a three-dimensional approach by forming an uneven interface between the carbon layer and the enlarged surface layer. This dimensional change allows further capacitance enhancement without being constrained by the limited foil thickness, effectively resolving the contradiction between capacitance improvement and thickness limitation.
3Reliability
If a film of metal nitride such as titanium nitride is formed on the cathode foil, then the capacitance and thermal stability are improved, but the deposition process is complicated and costly
Solution Approach 1:
The invention replaces the expensive and complex metal nitride deposition process with a simpler, cheaper carbon layer formation process using paste application. The carbon layer, while less durable than metal nitride, provides sufficient capacitance performance at a lower cost and with simpler manufacturing, resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The invention substitutes the vacuum arc deposition method (a complex physical vapor deposition process) with a simpler paste application and drying process. This mechanical substitution eliminates the need for vacuum equipment and complex deposition parameters, significantly reducing device complexity while maintaining acceptable capacitance performance.
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 electrode body achieves good capacitance even with a carbon layer, improving capacitance in high frequency regions and maintaining thermal stability, outperforming capacitors with titanium nitride deposits in certain conditions.
Implementation Method 1
A capacitance of the cathode side in this electrolytic capacitor is emerged by a storage action of the electric double layer formed on a boundary surface between a polar electrode and an electrolyte. Cations of the electrolyte are aligned at the boundary surface with the porous carbon layer and paired with electrons in the porous carbon layer at a very short distance
Implementation Method 2
a capacitance on the anode side is obtained by a dielectric polarization action of the dielectric oxide film layer
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.