Electrolytic Capacitor Separator Coating for Lower ESR

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Solution Overview

Problem

Existing methods for producing electrolytic capacitors using conductive polymers are inefficient, leading to high production costs due to excessive adhesion of conductive polymers to non-essential components, rather than the separator where it is most effective in reducing equivalent series resistance (ESR).

Innovation Solution

A method for producing electrolytic capacitors that involves preparing an anode foil, a cathode foil, and a fibrous structure, applying a conductive polymer-containing liquid to the fibrous structure, forming a separator by removing part of the solvent, and then assembling the capacitor element with the anode and cathode foils. This method ensures that the conductive polymer primarily adheres to the separator, optimizing its effect on reducing ESR.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the capacitor element is impregnated with a dispersion liquid containing a conductive polymer, then the conductive polymer can be attached to the separator to reduce ESR, but a large amount of the conductive polymer adheres to elements other than the separator, increasing production cost

Engineering Contradiction:

ImproveESR reduction effectVSAvoidconductive polymer waste

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The conductive polymer is applied to the separator in advance before assembling the capacitor element. The separator is prepared with the conductive polymer coating, then placed into the capacitor element which is subsequently impregnated with electrolytic solution. This preliminary action ensures the conductive polymer is positioned exactly where needed (on the separator) before the impregnation process, preventing waste on other components.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The production process is divided into separate steps: (1) preparing the separator with conductive polymer coating, (2) assembling the capacitor element, and (3) impregnating with electrolytic solution. This segmentation allows the conductive polymer application to be isolated to only the separator, preventing adhesion to other elements like the anode foil, cathode foil, or insulating components.

Inventive Principle:

Principle #1Segmentation

2Reliability

If a large amount of conductive polymer is used to ensure sufficient coating on the separator, then the ESR reduction effect is enhanced, but the production cost increases

Engineering Contradiction:

ImproveESR reduction effectVSAvoidconductive polymer consumption

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The separator is pre-coated with the conductive polymer dispersion liquid in a controlled manner, allowing precise control of the polymer amount applied. This preliminary coating ensures sufficient coverage on the separator for ESR reduction while preventing excessive polymer usage, since the polymer is applied only where needed before assembly.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The conductive polymer is applied locally and selectively to the separator surface, which is the specific location where ESR reduction is needed. This localized application ensures that the polymer is concentrated where it provides the most benefit (on the separator) rather than being wasted on other components, optimizing both effectiveness and efficiency.

Inventive Principle:

Principle #3Local quality

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 method effectively reduces the equivalent series resistance (ESR) of the electrolytic capacitor while minimizing the amount of conductive polymer used, thereby lowering production costs and improving efficiency.

Implementation Method 1

a conductive polymer-containing liquid containing a conductive polymer component and a first solvent; a step of forming a separator by removing at least part of the first solvent after applying the conductive polymer-containing liquid to the fibrous structure

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

a step of impregnating the capacitor element with an electrolytic solution

Methodology Applied

Scientific EffectImpregnation: Absorption (physical)

Implementation Method 3

a step of forming a separator by removing at least part of the first solvent after applying the conductive polymer-containing liquid to the fibrous structure

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS12266481B2Electrolytic capacitor including electrolytic solution having high electrical conductivity and method for producing same

Publication Date: 2025.04.01 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A method for producing an electrolytic capacitor includes: preparing an anode foil, a cathode foil, and a fibrous structure, the anode foil having a porous portion including a dielectric layer; preparing a conductive polymer-containing liquid, the conductive polymer-containing liquid containing a conductive polymer component and a first solvent;forming a separator by removing at least a part of the first solvent after applying the conductive polymer-containing liquid to the fibrous structure; forming a capacitor element from the anode foil, the separator, and the cathode foil; and impregnating the capacitor element with an electrolytic solution. An electrical conductivity of the electrolytic solution at 30° C. is 3.0 mS/cm or more.