Conductive Polymer Separator for Low-ESR Electrolytic Capacitors
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Solution Overview
Problem
Existing methods struggle to uniformly attach a sufficient amount of conductive polymer to electrolytic capacitors, particularly when high ripple currents are involved, leading to increased equivalent series resistance (ESR) and heat generation.
Innovation Solution
A method involving the use of a conductive polymer dispersion liquid with a specific viscosity and concentration, applied to a fiber structure containing a high percentage of synthetic fibers or cellulose and a paper strengthening agent, which is then stacked with anode and cathode foils to form a capacitor element, ensuring uniform attachment and reduced ESR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the concentration of the conductive polymer is increased to reduce ESR, then the ESR decreases, but the viscosity of the dispersion liquid increases making it difficult to permeate into the capacitor element
Solution Approach 1:
The patent changes the physical-chemical parameters of the dispersion liquid by selecting specific dispersion media (water, alcohol, or their mixtures) and controlling the conductive polymer concentration within 1-15 mass%, thereby achieving low viscosity even at higher polymer concentrations. This allows the liquid to permeate capacitor elements effectively while maintaining low ESR.
Solution Approach 2:
The patent uses composite dispersion media comprising water and/or alcohol as the base, combined with conductive polymer particles, to create a dispersion liquid that balances viscosity and conductivity. This composite approach enables effective permeation while delivering sufficient conductive polymer to reduce ESR.
2Reliability
If the amount of conductive polymer is increased to reduce ESR, then the ESR decreases, but it becomes difficult to uniformly attach the conductive polymer to the separator
Solution Approach 1:
The patent controls the viscosity of the dispersion liquid by adjusting the dispersion medium composition and polymer concentration, ensuring the liquid flows uniformly throughout the separator pores during immersion. This parameter control enables even distribution of conductive polymer at effective concentrations.
Solution Approach 2:
The patent creates a homogeneous dispersion liquid where conductive polymer particles are evenly distributed in the water/alcohol-based medium. This homogeneity ensures uniform attachment to the separator when the liquid permeates the separator structure, achieving both effectiveness and uniformity.
3Reliability
If the concentration of the conductive polymer is increased, then the ESR reduces, but the viscosity of the dispersion liquid increases
Solution Approach 1:
The patent fundamentally changes the viscosity parameter by using water and/or alcohol as dispersion media instead of traditional high-viscosity carriers. This allows the dispersion liquid to maintain low viscosity even when conductive polymer concentration is increased to 1-15 mass%, thereby reducing ESR without sacrificing flowability.
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 method allows for a significant reduction in ESR and improved heat resistance, making the electrolytic capacitor suitable for high ripple current applications.
Implementation Method 1
producing a separator by applying the conductive polymer dispersion liquid to the fiber structure and then removing at least a portion of the dispersion medium
Data Source
AI summary
Disclosed is a method for producing an electrolytic capacitor, the method including the steps of: preparing an anode foil that includes a dielectric layer, a cathode foil, and a fiber structure; preparing a conductive polymer dispersion liquid that contains a conductive polymer component and a dispersion medium; producing a separator by applying the conductive polymer dispersion liquid to the fiber structure and then removing at least a portion of the dispersion medium; and producing a capacitor element by sequentially stacking the anode foil, the separator, and the cathode foil. The dispersion medium contains water. The fiber structure contains a synthetic fiber in an amount of 50 mass % or more. The fiber structure has a density of 0.2 g/cm3 or more and less than 0.45 g/cm3.