Wet Electrolytic Capacitor Separator Using High MW Olefin Polymer

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Solution Overview

Problem

Conventional high voltage electrolytic capacitors used in implantable medical devices, such as defibrillators, face challenges due to the susceptibility of surfactant-based separators to reduced wettability over time, leading to performance degradation and increased costs.

Innovation Solution

A wet electrolytic capacitor design featuring an anodically oxidized sintered valve metal anode, a conductive-coated metal cathode, and a microporous membrane made from an olefin polymer with high weight-average molecular weight, eliminating the need for surfactants and enhancing physical strength and integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional surfactant-based separators are used to improve wettability, then initial performance is improved, but wettability is reduced over time leading to performance degradation

Engineering Contradiction:

Improveseparator wettabilityVSAvoidseparator performance duration

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent removes surfactants from the separator system entirely. The microporous membrane is made from olefin polymer without any surfactant additives, eliminating the source of wettability degradation over time while maintaining functional performance through the membrane's inherent microporous structure.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the fundamental material composition parameter by using high molecular weight olefin polymer (weight-average molecular weight of about 1,000,000 grams per mole or more) to create the microporous membrane. This parameter change provides inherent wettability and structural stability without relying on surfactants that degrade over time.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If surfactants are added to improve wettability, then initial separator performance is improved, but manufacturing cost increases

Engineering Contradiction:

Improveseparator wettabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates surfactants from the separator formulation, thereby removing the associated manufacturing cost while maintaining wettability through the microporous membrane structure made from olefin polymer.

Inventive Principle:

Principle #2Taking out (Extraction)

3Volume of moving object

If capacitor thickness is reduced to improve volumetric efficiency, then device size is minimized, but structural integrity may be compromised

Engineering Contradiction:

Improvecapacitor volumeVSAvoidseparator structural integrity

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The patent utilizes high molecular weight olefin polymer (weight-average molecular weight of about 1,000,000 grams per mole or more) to create a microporous membrane with superior mechanical strength. This parameter change in material composition allows the membrane to maintain structural integrity even when the overall capacitor thickness is reduced for improved volumetric efficiency.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a microporous membrane structure made from olefin polymer that provides both mechanical strength and functional performance. The microporous structure allows for thin design while maintaining integrity through the inherent properties of the high molecular weight polymer material.

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

The capacitor achieves high volumetric efficiency and energy density, maintaining performance over time with reduced thickness and cost, while minimizing the risk of performance degradation due to improved separator functionality.

Implementation Method 1

a microporous membrane that is positioned between the anode and cathode and contains an olefin polymer having a weight-average molecular weight of about 1,000,000 grams per mole or more

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

an anode that comprises an anodically oxidized pellet formed from a pressed and sintered valve metal powder

Methodology Applied

Scientific EffectAnodizing: Anodising

Implementation Method 3

an anode that comprises an anodically oxidized pellet formed from a pressed and sintered valve metal powder

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS10957493B2Wet electrolytic capacitor for an implantable medical device

Publication Date: 2021.03.23 KYOCERA AVX COMPONENTS CORP

AI summary

A wet electrolytic capacitor is provided. The capacitor comprises an anode that comprises an anodically oxidized pellet formed from a pressed and sintered valve metal powder, a cathode that comprises a metal substrate coated with a conductive coating, a microporous membrane that is positioned between the anode and cathode and contains an olefin polymer having a weight-average molecular weight of about 1,000,000 grams per mole or more, and a fluidic working electrolyte in communication with the anode and the cathode.