Electrolytic Capacitor Separator Band for Lower ESR
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Solution Overview
Problem
In existing electrolytic capacitors, the conductive polymer particles concentrate at the axial ends during drying, leaving large areas unfilled and preventing a sufficiently low Equivalent Series Resistance (ESR).
Innovation Solution
The electrolytic capacitor design includes a conductive polymer particle band extending in the longitudinal direction of the separator, covered by a cellulose derivative, which is immersed in a water solution and then dried to form a dense, wide distribution between electrode members, reducing axial movement and enhancing ESR reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the capacitor element is dried after being taken out of the liquid dispersed with particles of the conductive polymer, then the dispersion medium seeps out axially and the capacitor element is dried, but the particles of the conductive polymer move axially and concentrate in an axial end part, leaving a large area unfilled and making it impossible to attain a sufficiently low ESR
Solution Approach 1:
The patent applies preliminary action by first immersing the capacitor element in a water solution of cellulose derivative and drying it to form a preliminary layer before immersing in the conductive polymer dispersion liquid. This preliminary layer prevents axial concentration of conductive polymer particles during subsequent drying, ensuring uniform distribution and low ESR.
Solution Approach 2:
The cellulose derivative acts as an intermediary substance between the electrode foils and the conductive polymer particles. It forms a gel structure that restrains particle movement during drying, mediating the interaction between the dispersion medium and conductive polymer particles to achieve uniform distribution.
2Ease of manufacture
If the conductive polymer particles are allowed to move freely during drying, then the drying process is simple, but the particles concentrate at axial ends and fail to fill large areas between electrode foils
Solution Approach 1:
The cellulose derivative serves as an intermediary that simplifies the drying process while ensuring precise particle distribution. The gel structure formed by cellulose derivative restrains particle movement passively during drying, eliminating the need for complex drying control mechanisms while achieving uniform coverage.
Solution Approach 2:
The patent changes the physical state parameter of the dispersion medium by using a gel-forming cellulose derivative that transitions from liquid to gel state during drying. This parameter change restrains particle movement and ensures uniform distribution without complicating the drying process.
3Productivity
If a large area between electrode foils is left unfilled with conductive polymer, then the manufacturing process is simpler, but it becomes impossible to attain a sufficiently low ESR
Solution Approach 1:
The preliminary immersion in cellulose derivative solution creates a protective layer that prevents particle concentration during drying. This preliminary action ensures complete area coverage without requiring complex manufacturing processes or multiple immersion steps, maintaining high productivity while achieving low ESR.
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 design effectively reduces ESR by ensuring a large area coverage of conductive polymer, maintaining a dense and uniform distribution, thereby improving capacitor performance.
Implementation Method 1
the cellulose derivative is a gelator that gelates water on being heated to 45°C or higher
Implementation Method 2
The capacitor element is impregnated with a conductive polymer and an electrolyte solution. The capacitor element is immersed in a liquid dispersed with particles of a conductive polymer, and is then taken out of the liquid and dried
Implementation Method 3
the electrolyte solution acts to repair defects in the dielectric coat, and this helps increase the withstand voltage of the electrolytic capacitor
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
In an electrolytic capacitor 1 having a capacitor element 10 housed inside a body case 3 where the capacitor element has a first electrode member 11 and a second electrode member 12 wound up with a separator 13 in between and where the capacitor element holding an electrolyte solution, there is provided, between the first and second electrode members 11 and 12, a conductive polymer particle band 23 in which conductive polymer particles of a conductive polymer 22 in a dense state are disposed to extend in the longitudinal direction of the separator 13, the conductive polymer particle band 23 contains a cellulose derivative 21, and the conductive polymer particle band 23 is provided to cover, within at least one of regions on opposite sides of the center line of the separator 13 in its lateral direction, one half or more of the region in the lateral direction.