Separator-Free Electrolytic Capacitor Structure for High Capacitance Density

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Solution Overview

Problem

The presence of a separator in electrolytic capacitors reduces volumetric capacity density while preventing short circuits and leakage current, but its absence leads to reliability issues.

Innovation Solution

An electrolytic capacitor design without a separator, utilizing a conductive polymer layer with insulating fibers or particles between the anode and cathode foils, ensuring a sufficient distance and enhancing reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separator is used between anode foil and cathode foil, then short circuits and leakage current are suppressed, but volumetric capacity density decreases

Engineering Contradiction:

Improvesuppression of short circuits and leakage currentVSAvoidvolumetric capacity density

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The invention extracts the separator component from the capacitor structure and replaces it with a conductive polymer layer containing insulating particles. This eliminates the need for a separate separator while maintaining electrical insulation functionality, thereby increasing volumetric capacity density without compromising reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the functions of the conductive polymer layer and the separator into a single integrated layer. The conductive polymer layer is formulated with insulating particles dispersed throughout, combining electrical conductivity with physical insulation properties, thus eliminating the need for a separate separator component.

Inventive Principle:

Principle #5Merging (Combining)

2Volume of stationary object

If a separator is removed to increase volumetric capacity density, then more space is available for active materials, but reliability decreases due to increased risk of short circuits

Engineering Contradiction:

Improvevolumetric capacity densityVSAvoidrisk of short circuits and leakage current

Core Design Contradiction:

Volume of stationary objectVSReliability

Solution Approach 1:

The invention employs a composite material structure where insulating particles are dispersed within a conductive polymer matrix. This composite layer simultaneously provides electrical conductivity for capacitor operation and physical insulation to prevent short circuits, enabling high volumetric capacity density without compromising reliability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention changes the physical and chemical parameters of the conductive polymer layer by incorporating insulating particles with specific properties (size, shape, concentration). This modifies the layer's electrical and mechanical characteristics to achieve both high conductivity and sufficient insulation, allowing the separator to be removed while maintaining reliability.

Inventive Principle:

Principle #35Parameter changes

3Volume of stationary object

If the distance between anode foil and cathode foil is reduced to increase capacity density, then volumetric efficiency improves, but the risk of short circuits and performance degradation increases

Engineering Contradiction:

Improvevolumetric capacity densityVSAvoidwithstand voltage and performance stability

Core Design Contradiction:

Volume of stationary objectVSReliability

Solution Approach 1:

The conductive polymer layer containing insulating particles acts as an intermediary between the anode and cathode foils. This intermediate layer maintains a sufficient physical distance between the electrodes, preventing direct contact and short circuits, while still allowing the capacitor to achieve high volumetric capacity density through optimized space utilization.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design achieves high volumetric capacitance density and reliability by maintaining a safe distance between the anode and cathode foils without a separator, reducing ESR and performance degradation.

Implementation Method 1

a conductive composition comprising a conductive polymer synthesized by oxidatively polymerizing pyrrole or a derivative thereof using an organic sulfonate and a persulfate

Methodology Applied

Scientific EffectOxidative polymerization: Oxidation

Implementation Method 2

a layer containing a conductive polymer and an insulating material disposed between the dielectric layer and the cathode foil, wherein the insulating material is at least one kind of material selected from the group consisting of insulating fibers and insulating particles

Methodology Applied

Scientific EffectPhysical barrier: Physical Containment

Data Source

PatentUS20260058067A1Electrolytic capacitor and method for manufacturing electrolytic capacitor

Publication Date: 2026.02.26 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

An electrolytic capacitor disclosed herein includes: a stacked body of an anode foil having a dielectric layer formed on a surface thereof and a cathode foil; and a layer containing a conductive polymer and an insulating material disposed between the dielectric layer and the cathode foil. The insulating material is at least one kind of material selected from the group consisting of insulating fibers and insulating particles. No separator is disposed between the anode foil and the cathode foil.