Aqueous EDLC Electrolyte for Low Leakage at High Temperature
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Solution Overview
Problem
Existing electric double-layer capacitors using sulfuric acid as electrolyte face challenges in maintaining low leakage current and high reliability at high temperatures, leading to rapid deterioration and reduced product life.
Innovation Solution
Utilizing an aqueous electrolytic solution with a water-soluble electrolyte having a Hammett acidity function H0 of −2.8 or higher and vapor pressure of 400 mmHg or lower, along with a specific mass ratio of activated carbon, to create an electric double-layer capacitor that maintains low leakage current and high reliability even in high temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If sulfuric acid is used as the electrolytic solution, then high conductivity is achieved, but leakage current increases and reliability deteriorates at high temperatures
Solution Approach 1:
The patent changes the chemical parameters of the electrolytic solution by replacing sulfuric acid with phosphoric acid, adjusting the acidity and composition to achieve both high conductivity and low leakage current at high temperatures
Solution Approach 2:
The patent uses a water-soluble electrolyte that can be easily replaced and regenerated, sacrificing the long-term stability of sulfuric acid for easier maintenance and replacement of the electrolytic solution
2Loss of energy
If sulfuric acid is used as the electrolytic solution, then high conductivity is achieved, but electrode and separator deterioration accelerates
Solution Approach 1:
The patent converts the harmful strong acidity of sulfuric acid into beneficial moderate acidity of phosphoric acid, which provides sufficient conductivity while reducing the harmful corrosive effects on electrodes and separators
Solution Approach 2:
The patent introduces phosphoric acid as an intermediary substance that mediates between the need for high conductivity and the need to protect electrodes from corrosion, providing a balanced chemical environment
3Power
If high temperature operation is required, then output performance is improved, but product life decreases due to electrolyte evaporation
Solution Approach 1:
The patent changes the physical parameters of the electrolytic solution by selecting phosphoric acid with lower vapor pressure, enabling high-temperature operation while preventing electrolyte loss through evaporation
Solution Approach 2:
The patent uses a water-soluble electrolyte formulation that can be easily replenished if evaporation occurs, making the system more resilient to high-temperature operation effects
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 a prolonged product life of 6,000 to 9,000 hours at 85°C and 2,000 hours at 105°C, with reduced electrode damage and evaporation, ensuring high reliability and stability.
Implementation Method 1
An electric double-layer capacitor is a capacitor in which an electric double layer having a thickness of several nanometers formed at the interface between an electrically charged solid and an electrolytic solution in contact with the solid is used as a dielectric
Implementation Method 2
Electric double-layer capacitors can be classified into two types according to the type of the electrolytic solution used, i.e., those that use a non-aqueous (organic) electrolytic solution and those that use an aqueous electrolytic solution
Data Source
AI summary
An electric double-layer capacitor capable of maintaining a low leakage current over a long period of time even in a high temperature range, having high reliability in the high temperature range, and thereby making it possible to extend the life of an apparatus using the electric double-layer capacitor is provided. Further, a method for manufacturing such an electric double-layer capacitor is also provided. An electric double-layer capacitor and its manufacturing method are characterized in that an aqueous electrolytic solution containing a water-soluble electrolyte of which a Hammett acidity function H0 at a temperature of 25° C. is −2.8 or higher and a vapor pressure at a temperature of 100° C. is 400 mmHg or lower is used.