Electrolytic Capacitor ESR Stability via Carboxylic Acid Solutes
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Solution Overview
Problem
Conventional electrolytic capacitors with glycol compounds as solvents exhibit increased Equivalent Series Resistance (ESR) over time under long-term load tests at high temperatures, compromising their withstand voltage and heat resistance characteristics.
Innovation Solution
An electrolytic capacitor design incorporating a solvent with a glycol compound and a solute containing a carboxylic acid component in a specific mass ratio, which improves the orientation and crystallinity of the conductive polymer in the solid electrolyte layer, maintaining low ESR and enhancing heat resistance by preventing solvent volatility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glycol compound is used as the electrolytic solution solvent, then initial ESR is low and conductivity is good, but ESR increases sharply over time under long-term load test at high temperature
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolytic solution by introducing a carboxylic acid component with specific molecular weight (100-500) and controlling its concentration (0.1-10 mmol/L). This parameter change transforms the electrolytic solution from a simple glycol compound system to a complex system with carboxylic acid-glycol interactions, which prevents the sharp ESR increase observed in conventional systems under long-term high temperature operation.
Solution Approach 2:
The patent creates a composite electrolytic solution system by combining a carboxylic acid component with a glycol compound solvent. This composite system leverages the beneficial properties of both components: the glycol compound provides good initial conductivity and low ESR, while the carboxylic acid component forms protective interactions that prevent degradation over time, thereby resolving the contradiction between initial performance and long-term stability.
2Reliability
If the electrolytic solution composition is optimized for low initial ESR, then conductivity is improved, but withstand voltage characteristics deteriorate
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: the carboxylic acid component concentration (0.1-10 mmol/L), molecular weight (100-500), and the type of glycol compound. This multi-parameter optimization achieves a balance where the electrolytic solution maintains low ESR (reducing energy loss) while also improving withstand voltage characteristics through the protective carboxylic acid-glycol interactions that prevent degradation under electrical stress.
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 proposed design achieves excellent withstand voltage characteristics and heat resistance while maintaining low ESR both initially and over time, suppressing conductivity deterioration and corrosion, thereby improving the capacitor's reliability and performance.
Implementation Method 1
improves the orientation and crystallinity of the conductive polymer in the solid electrolyte layer
Implementation Method 2
preventing solvent volatility
Data Source
AI summary
An electrolytic capacitor includes: an anode body having a dielectric layer; a solid electrolyte layer in contact with the dielectric layer; and an electrolytic solution. The electrolytic solution contains a solvent and a solute. The solvent contains a glycol compound. The solute contains a carboxylic acid component and a base component. A ratio of the carboxylic acid component in the solute is 200 parts by mass or more with respect to 100 parts by mass of the base component.