Electrochemical Capacitor Electrode Ratio for Float Charge Stability
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Solution Overview
Problem
Electrochemical capacitors deteriorate in performance during float charge due to oxidative decomposition of the lactone compound used in the electrolytic solution, which is exacerbated by high potentials at the positive electrode.
Innovation Solution
The capacity of the positive electrode is made greater than the negative electrode, with a ratio of 1.1 to 1.6 times, to lower the potential and suppress oxidative decomposition, while maintaining a high capacitance and reducing reductive decomposition at the negative electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the positive electrode capacity is increased to suppress oxidative decomposition of the lactone compound, then float characteristics are improved, but the overall capacitance of the capacitor decreases
Solution Approach 1:
The patent changes the capacity ratio parameter between positive and negative electrodes from the conventional negative electrode being larger to positive electrode being larger (1.05-1.3 times). This parameter inversion resolves the contradiction by suppressing oxidative decomposition through higher positive electrode capacity while maintaining acceptable overall capacitance through optimized ratio control
Solution Approach 2:
The patent uses a composite electrode configuration where the positive electrode comprises both carbon material and quinone derivative, creating a synergistic effect that provides both high capacity and stability, thereby improving float characteristics while maintaining capacitance
2Reliability
If the positive electrode capacity is made larger than the negative electrode capacity, then oxidative decomposition is suppressed, but the electrode structure becomes asymmetric and more complex
Solution Approach 1:
The patent deliberately introduces asymmetry in electrode capacities, making the positive electrode capacity larger than the negative electrode capacity (1.05-1.3 times). This asymmetric design directly addresses the oxidative decomposition issue by providing sufficient capacity buffer at the positive electrode while maintaining a manageable structural complexity through controlled ratio limits
3Reliability
If the capacity ratio between positive and negative electrodes is optimized to 1.05-1.3 times, then float charge performance is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent establishes a specific parameter range (1.05-1.3 times) for the positive to negative electrode capacity ratio. This quantified parameter specification improves float charge performance while providing clear manufacturing targets that balance precision requirements with practical manufacturability
Solution Approach 2:
The patent specifies a capacity ratio range rather than a single precise value, allowing some deviation (1.05-1.3 times) while still achieving the desired float charge performance. This partial precision approach reduces manufacturing difficulty compared to requiring exact ratio control
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 configuration effectively suppresses the deterioration of float characteristics by minimizing decomposition of the lactone compound and maintaining high capacitance and low resistance, ensuring improved performance under float charge.
Implementation Method 1
an electrochemical capacitor includes a pair of electrodes and an electrolytic solution, and at least one of the pair of electrodes contains an active material capable of adsorbing and desorbing ions
Implementation Method 2
Electrochemical capacitors deteriorate in performance during float charge due to oxidative decomposition of the lactone compound used in the electrolytic solution
Data Source
AI summary
An electrochemical capacitor includes a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolytic solution. The electrolytic solution contains a lactone compound. A capacity of the positive electrode is greater than a capacity of the negative electrode and is less than or equal to 1.6 times of the capacity of the negative electrode.