Capacitor Electrode Void Structure for Resistance Control
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Solution Overview
Problem
Current electric double layer capacitors degrade significantly due to increased resistance over long-term charge-discharge cycling, affecting their durability and temperature characteristics.
Innovation Solution
The electrode configuration includes carbon particles with specific void distributions, where the ratio of larger voids to smaller voids is optimized to enhance ion diffusion and capacitance, using a conductive base member with activated carbon, binder, and conductive additives, ensuring a value of (VA×VA)/(VB×M) greater than 0.022, which maintains charge-discharge characteristics and extends the capacitor's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If activated carbon with very large surface area is used to adsorb ions, then capacitance is increased, but resistance increases over long-term charge-discharge cycling causing severe degradation
Solution Approach 1:
The patent applies porous materials by controlling the void structure within the electrode part. Specifically, it defines voids with diameters of 0.003 μm to 0.2 μm and controls the void volume ratio to be 0.05 to 0.60 mL/g. This porous structure allows efficient ion diffusion pathways while maintaining large surface area contact between electrolyte and activated carbon, thereby achieving both high capacitance and low resistance increase during cycling.
Solution Approach 2:
The patent applies parameter changes by precisely controlling physical parameters of the electrode structure. It specifies void diameter range (0.003-0.2 μm), void volume ratio (0.05-0.60 mL/g), and particle density (1.70-2.10 g/mL). These parameter optimizations balance ion accessibility with structural stability, enabling the capacitor to maintain performance over long-term cycling while preserving high capacitance.
2Reliability
If the ratio of electrolytic solution volume to void volume is controlled to improve durability and temperature characteristics, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by defining specific ranges for void diameter (0.003-0.2 μm), void volume ratio (0.05-0.60 mL/g), and particle density (1.70-2.10 g/mL). These controlled parameters automatically ensure appropriate electrolyte distribution and void structure, achieving improved temperature characteristics and durability without requiring complex manufacturing processes or additional control mechanisms.
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 stabilizes the charge-discharge characteristics, reduces resistance increase, and extends the lifespan of electric double layer capacitors, allowing them to maintain performance under severe conditions such as higher voltages and varying temperatures.
Implementation Method 1
Positive and negative electrodes of an electric double layer capacitor contain activated carbon having a very large surface area to adsorb ions
Data Source
AI summary
A capacitor electrode includes a conductive base member and an electrode part electrically connected to the base member. The electrode part contains carbon particles of a first carbon material capable of adsorbing and desorbing ions. The electrode part further contains voids including first voids with diameters of not less than 0.2 μm and not more than 1.0 μm, and second voids with diameters of not less than 0.05 μm and less than 0.2 μm. The value of (VA×VA)/(VB×M) is greater than 0.022, where VA is the sum of the volumes of the first voids, VB is the sum of the volumes of the second voids, and M is the volume of the electrode part per unit weight of the electrode part.