Carbon-Coated Cathode Foil With Uneven Interface for Stable 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 in normal and high temperature environments compared to those with metal nitride deposits.

Innovation Solution

An electrode body for an electrolytic capacitor featuring a cathode foil with an enlarged surface layer and a carbon layer, where the interface between the enlarged surface layer and the carbon layer has an uneven shape, enhancing capacitance and manufacturing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal nitride deposition process is used on cathode foil, then capacitance and thermal stability are improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvecapacitance and thermal stabilityVSAvoiddeposition process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the expensive and complex metal nitride deposition process with a simpler, more cost-effective carbon layer formation process. The carbon layer is applied through conventional coating methods rather than requiring vacuum arc deposition, significantly reducing manufacturing complexity and cost while maintaining acceptable capacitance and thermal stability performance

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the material parameter from metal nitride to carbon, and modifies the surface morphology parameter by creating an enlarged surface layer with specific roughness (Ra: 0.5-5 μm) and pore structure. These parameter changes enable the carbon layer to achieve adequate electrical performance without requiring complex deposition processes

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If porous carbon layer is formed on cathode foil by paste application, then manufacturing complexity is reduced, but capacitance decreases in normal and high temperature environments

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidcapacitance in normal and high temperature environments

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies local quality by creating an enlarged surface layer with specific roughness (Ra: 0.5-5 μm) and pore structure on the cathode foil surface. This localized surface modification increases the effective surface area and improves electrolyte contact, thereby enhancing capacitance in the carbon layer system without requiring complex manufacturing processes

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure combining the cathode foil base material with a carbon layer, where the carbon layer is applied over the enlarged surface layer. This composite structure leverages both the mechanical properties of the foil and the electrical properties of carbon, achieving improved capacitance and thermal stability while maintaining manufacturing simplicity

Inventive Principle:

Principle #40Composite materials

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 and thermal stability, and reducing the complexity and cost associated with metal nitride deposition processes.

Implementation Method 1

having an enlarged surface layer formed on a surface

Methodology Applied

Scientific EffectSurface enlargement:

Implementation Method 2

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

Methodology Applied

Scientific EffectElectric double layer:

Implementation Method 3

an interface between the enlarged surface layer and the carbon layer has an uneven shape

Methodology Applied

Scientific EffectInterface unevenness:

Data Source

PatentUS12340954B2Electrode body, electrolytic capacitor provided with electrode body, and method for producing electrode body

Publication Date: 2025.06.24 NIPPON CHEMI CON CORP

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.