Nonaqueous EDLC Electrolyte Purity for Long-Term Capacity Retention
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Solution Overview
Problem
Existing nonaqueous electrolytic solutions for electric double layer capacitors have insufficient durability, leading to capacity degradation and increased resistance over time.
Innovation Solution
A nonaqueous electrolytic solution with a controlled alkali metal cation concentration of 0.1 to 30 ppm, specifically using a quaternary ammonium salt dissolved in a nonaqueous solvent, is developed to enhance the durability of electric double layer capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nonaqueous electrolytic solutions are used, then the electric double layer capacitor can be manufactured, but the durability is insufficient leading to capacity degradation and resistance increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the alkali metal cation concentration within the range of 0.1 to 30 ppm. This specific concentration range was determined through extensive experimentation to optimize the balance between preventing capacity degradation and maintaining electrolyte conductivity. The parameter optimization directly addresses the durability issue by eliminating excessive alkali metal cations that cause capacity fade while retaining enough to maintain proper electrolyte function.
Solution Approach 2:
The patent employs local quality by using highly pure reagents with specifically controlled impurity profiles during electrolyte preparation. The quaternary ammonium salt and solvent are selected and purified to achieve specific purity levels, with particular attention to minimizing alkali metal cation content. This localized purity control at the material level translates to improved overall durability of the capacitor.
2Reliability
If alkali metal cation concentration is reduced to improve durability, then capacity deterioration is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-purifying the quaternary ammonium salt and solvent to achieve the required purity levels before mixing. The reagents are selected and processed in advance to minimize alkali metal cation content, and the mixing process is designed to prevent contamination. This preliminary preparation work ensures that the final electrolyte meets the strict 0.1 to 30 ppm specification without requiring complex post-processing or quality control measures during assembly.
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 solution results in highly durable electric double layer capacitors with reduced capacity deterioration and resistance increase, maintaining performance over a long period.
Implementation Method 1
a nonaqueous electrolytic solution prepared by dissolving a quaternary ammonium salt represented by a general formula (I) as an electrolyte in a nonaqueous solvent
Implementation Method 2
Electric double layer capacitors (EDLCs) are power storage devices that store electric power by using a phenomenon in which ions in an electrolytic solution form an electric double layer due to physical adsorption to an electrode when an electric field is applied to the electrolytic solution
Data Source
AI summary
The present invention provides a nonaqueous electrolytic solution that provides an electric double layer capacitor having excellent durability. The nonaqueous electrolytic solution of the present invention is a nonaqueous electrolytic solution for electric double layer capacitors prepared by dissolving a quaternary ammonium salt as an electrolyte in a nonaqueous solvent, and the nonaqueous electrolytic solution has an alkali metal cation concentration of 0.1 to 30 ppm.