Carbon-Layer Capacitor Separator Density for Short-Circuit Suppression
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Solution Overview
Problem
Existing capacitors face issues with short circuits between positive and negative electrode foils due to carbon separation from the negative electrode foil, which adversely affects the insulating function of the separator.
Innovation Solution
A capacitor design incorporating a negative electrode foil with a carbon layer, using a separator with a density of 4.0×10−3×WPA or more, where WPA is the carbon amount per square centimeter, and preferably using a kraft separator to maintain insulation and prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a carbon layer is formed on the negative electrode foil to increase electrostatic capacitance, then the electrostatic capacitance is improved, but carbon separation occurs which deteriorates the insulating function of the separator
Solution Approach 1:
The patent applies parameter changes by specifying a minimum density threshold for the separator (ρ ≥ 4.0×10^-3×WPA g/cm³) to prevent carbon penetration. By adjusting the separator's density parameter based on the carbon amount on the negative electrode, the insulating function is maintained even when carbon is present, thus resolving the contradiction between achieving high capacitance and maintaining reliability.
Solution Approach 2:
The patent employs composite materials by combining the negative electrode foil with carbon layer and the separator with specific density characteristics. This composite structure allows the carbon to provide electrostatic capacitance while the dense separator material prevents carbon separation, thereby maintaining both high capacitance and reliable insulation.
2Reliability
If the separator density is increased to prevent carbon penetration, then the insulating function is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent simplifies the complexity by establishing a clear quantitative relationship for separator density (ρ ≥ 4.0×10^-3×WPA g/cm³) based on carbon amount. This straightforward parameter specification makes it easier to control manufacturing processes and quality inspection, reducing complexity while ensuring reliable insulation.
3Reliability
If a kraft separator is used to enhance short-circuit suppression, then the insulating function is improved, but the manufacturing cost increases
Solution Approach 1:
The patent provides flexibility in manufacturing by specifying a minimum density threshold rather than mandating kraft paper specifically. This allows manufacturers to choose from various materials (kraft paper, synthetic papers, films) that meet the density requirement, enabling cost optimization while maintaining effective short-circuit suppression.
Data Source
AI summary
A capacitor includes a positive electrode foil, a negative electrode foil, and a separator disposed between the positive and negative electrode foils. The negative electrode foil includes a carbon layer, and the separator is in contact with the carbon layer. The separator has a density [symbol: ρ, unit: g/cm3] satisfying the formula:ρ≥4.0×10-3×WPA,where WPA is the amount of carbon per square centimeter of the separator [unit: μg/cm2].