Electric Double Layer Capacitor Ion Ratio Optimization
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Solution Overview
Problem
Existing electric double layer capacitors face limitations in achieving high voltage ratings while maintaining low internal resistance and efficient charge-discharge characteristics, especially at low temperatures, due to constraints on electrolyte amount and concentration.
Innovation Solution
The solution involves controlling the ratio of ions in the organic electrolytic solution within the capacitor, defined by the rated capacitance and voltage, to optimize the void volumes of electrodes and separators, ensuring a balanced ion content ratio between 1.7 to 3.5, and using an ionic liquid with specific electrolyte concentrations to maintain low internal resistance and high energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of electrolytic solution is reduced to increase energy density, then the energy density is improved, but the internal resistance increases and charge-discharge efficiency decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the electrolyte concentration within a specific range (0.5-2.0 mol/L) and controlling the void volume ratio of electrodes and separator (1.0-3.0). This allows achieving high energy density while maintaining low internal resistance by precisely adjusting these parameters rather than simply reducing electrolyte amount.
2Reliability
If the electrolyte concentration is increased to reduce internal resistance, then the internal resistance is improved, but the charge-discharge efficiency at low temperature deteriorates
Solution Approach 1:
The patent uses parameter changes by selecting an optimal electrolyte concentration range (0.5-2.0 mol/L) that balances internal resistance and low-temperature performance. This specific concentration range ensures sufficient ionic conductivity at low temperatures while maintaining acceptable internal resistance at operating temperature.
3Quantity of substance
If the void volume of electrodes and separator is reduced to increase energy density, then the energy density is improved, but the ion transport capability deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the void volume ratio of electrodes and separator within 1.0-3.0 and optimizing electrolyte concentration. This ensures sufficient space for ion transport while maximizing energy density, resolving the contradiction between compact structure and ion mobility.
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 enables electric double layer capacitors with high voltage ratings, excellent high-current charge-discharge characteristics, and improved durability and low internal resistance in low-temperature environments, while maintaining efficient energy storage and discharge properties.
Implementation Method 1
electric double layer capacitor having a pair of current collectors, a positive polarizable electrode provided on one of the pair of current collectors, a negative polarizable electrode provided on the other of the pair of current collectors
Implementation Method 2
an organic electrolytic solution which impregnates at least the positive and negative polarizable electrodes and the separator
Data Source
AI summary
An electric double layer capacitor is composed of a pair of current collectors, a positive polarizable electrode provided on one of the pair of current collectors, a negative polarizable electrode provided on the other of the pair of current collectors, a separator between the positive and negative polarizable electrodes, and an organic electrolytic solution which impregnates at least the positive and negative polarizable electrodes and the separator. The capacitor has a theoretical amount of ions Qt defined asQt (moles)=C×V÷96,500,wherein C is the rated capacitance (farads) of the capacitor and V is the rated voltage (volts), and an amount of ions Qe in the organic electrolytic solution, such that Qe/Qt=1.7 to 3.5. The capacitor has a high voltage rating, excellent cycle characteristics during high-current charging and discharging, and a low internal resistance in low-temperature environments.