Electrolytic Solution with Hydrophilic Substituents for Capacitor ESR Control

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Solution Overview

Problem

Conventional electrolytic capacitors experience a significant increase in equivalent series resistance (ESR) over time in high temperature environments due to esterification and amidation reactions, which reduces their heat-resisting and ripple current properties and shortens their lifetime.

Innovation Solution

The use of a carboxylic acid-based electrolytic solution with hydrophilic substituents bonded to the terminal carbons of the main chain, which acts as a steric hindrance to inhibit esterification and amidation reactions, and hydrophilic substituents on other carbons to reduce the hydrophobic properties of reaction products, preventing their precipitation and maintaining conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional carboxylic acid electrolyte is used, then the electrolytic capacitor shows good initial performance, but the ESR increases significantly over time in high temperature environments due to esterification and amidation reactions

Engineering Contradiction:

Improveheat-resisting propertyVSAvoidlifetime

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical parameters of the electrolyte by introducing carboxylic acids with specific molecular structures (formula A and B) that have steric hindrance effects. This structural modification prevents esterification and amidation reactions, thereby maintaining low ESR and improving heat resistance and lifetime in high-temperature environments.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite electrolyte formulations combining carboxylic acids with specific structures (formula A and B) along with other electrolyte components. This composite approach creates synergistic effects that suppress harmful reactions while maintaining good electrical properties, achieving both high reliability and long lifetime.

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

This approach effectively suppresses the increase in ESR in high temperature environments, enhancing the heat-resisting and ripple current properties and extending the lifetime of electrolytic capacitors.

Implementation Method 1

this carboxyl group tends to undergo an esterification reaction with alcohol such as ethylene glycol as a solvent in a high temperature environment

Methodology Applied

Scientific EffectEsterification reaction: Chemical Bonding

Implementation Method 2

The reaction product subsequently undergoes an amidation reaction with ammonia, amine, or the like, contained in a general electrolytic solution

Methodology Applied

Scientific EffectAmidation reaction: Chemical Bonding

Implementation Method 3

the alkyl group is adjacent to the carboxyl group to serve as a steric hindrance, thus inhibiting the reaction between the carboxyl group and alcohol such as ethylene glycol as a solvent

Methodology Applied

Scientific EffectSteric hindrance:

Data Source

PatentUS8279581B2Electrolytic solution for electrolytic capacitor and electrolytic capacitor using the same

Publication Date: 2012.10.02 PANASONIC HOLDINGS CORP

AI summary

An electrolytic solution for an electrolytic capacitor includes a solvent and an electrolyte dissolved in the solvent. This electrolyte includes at least one of a carboxylic acid and a salt of the carboxylic acid. The carboxylic acid has a carboxyl group and at least one or more of substituents bonded to each terminal carbon of a straight main chain. The substituent bonded to the each terminal carbon of the main chain is hydrophilic, and/or a hydrophilic substituent is bonded to at least one of carbons other than the both terminal carbons of the main chain.