Electrolytic Capacitor Roughened Cathode Adhesion

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Solution Overview

Problem

Conventional electrolytic capacitors face challenges in reducing Equivalent Series Resistance (ESR) while maintaining high capacitance, especially when using an electrolyte solution, due to insufficient adhesion between the conductive polymer layer and the inorganic conductive layer, which is exacerbated by the formation of an inorganic conductive layer on the cathode side.

Innovation Solution

The electrolytic capacitor incorporates a conductive polymer layer formed using a dispersion or solution containing a conductive polymer, with a roughened cathode foil surface to enhance adhesion, featuring an inorganic conductive layer on the cathode foil that includes materials like carbon, nickel, or titanium, and a specific surface expansion rate to balance contact regions and prevent electrolyte solution infiltration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a conductive polymer layer is formed using a dispersion or solution containing a conductive polymer, then the ESR is reduced and high capacitance is secured, but the adhesion between the conductive polymer layer and the inorganic conductive layer is insufficient, especially when an electrolyte solution is used

Engineering Contradiction:

ImproveESR (Equivalent Series Resistance)VSAvoidadhesion between conductive polymer layer and inorganic conductive layer

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The cathode foil surface is roughened before forming the inorganic conductive layer and conductive polymer layer. This preliminary surface preparation creates anchor points that enhance adhesion between layers, preventing delamination when electrolyte solution is used while maintaining low ESR and high capacitance performance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses a composite structure combining roughened cathode foil, inorganic conductive layer (carbon, nickel, or titanium), and conductive polymer layer. This multi-layer composite approach provides both the adhesion needed for reliability and the conductive properties needed for low ESR and high capacitance

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If an inorganic conductive layer is formed on the cathode side to reduce ESR, then energy loss is reduced, but adhesion between the conductive polymer layer and inorganic conductive layer becomes insufficient

Engineering Contradiction:

ImproveESR (Equivalent Series Resistance)VSAvoidadhesion between layers

Core Design Contradiction:

Loss of energyVSStrength

Solution Approach 1:

The cathode foil surface is roughened before depositing the inorganic conductive layer. This preliminary roughening creates mechanical interlocking that strengthens adhesion between the inorganic layer and subsequent conductive polymer layer, preventing delamination while maintaining the low ESR benefit of the inorganic conductive layer

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The roughened cathode foil surface creates a porous or textured structure that increases surface area and provides mechanical anchoring for the inorganic conductive layer. This porous structure enhances adhesion strength while allowing the inorganic layer to maintain its conductive function for reducing ESR

Inventive Principle:

Principle #31Porous 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

This configuration effectively reduces ESR and secures high capacitance, even with the use of an electrolyte solution, by improving adhesion and preventing electrolyte infiltration, thus maintaining performance over time.

Implementation Method 1

The cathode foil has a roughened surface, and the roughened surface of the cathode foil has a surface expansion rate ranging from 1.5 cm2/cm2 to 500 cm2/cm2, inclusive

Methodology Applied

Scientific EffectSurface roughening:

Implementation Method 2

a conductive polymer layer disposed between the anode foil and the cathode foil. The conductive polymer layer includes a conductive polymer in contact with at least a part of a surface of the first layer

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

The cathode foil is provided with a first layer disposed on the cathode foil, the first layer including at least one selected from the group consisting of carbon, nickel, a nickel compound, titanium, and a titanium compound

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11348739B2Electrolytic capacitor

Publication Date: 2022.05.31 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

An electrolytic capacitor includes a capacitor element and a solution containing a solute. The capacitor element includes: an anode foil provided with a dielectric layer on the anode foil; a cathode foil disposed to face the anode foil; and a conductive polymer layer disposed between the anode foil and the cathode foil. The cathode foil is provided with a first layer disposed on the cathode foil, the first layer including at least one selected from the group consisting of carbon, nickel, a nickel compound, titanium, and a titanium compound. The conductive polymer layer includes a conductive polymer in contact with at least a part of a surface of the first layer. The cathode foil has a roughened surface, and the roughened surface of the cathode foil has a surface expansion rate ranging from 1.5 cm2/cm2 to 500 cm2/cm2, inclusive.