Electrolytic Capacitor Polymer Layering for Low-ESR Reliability
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Solution Overview
Problem
Existing methods for manufacturing electrolytic capacitors with conductive polymer layers often result in insufficient formation, leading to reduced initial capacity, increased equivalent series resistance (ESR), and reliability issues, as well as potential leakage currents and short circuits.
Innovation Solution
A method involving a polymer layer formation step where a conductive polymer layer is formed on a separator and selected surfaces of an anode and cathode foil, followed by a stacked body formation step and an impregnation step, using an application liquid containing a conductive polymer component, water, and an organic compound that remains in the conductive polymer layer after medium removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the wound body is impregnated with a dispersion liquid containing conductive polymer particles, then the conductive polymer layer is formed, but the high viscosity of the dispersion liquid prevents sufficient formation of the conductive polymer layer inside the wound body
Solution Approach 1:
The invention divides the conductive polymer layer formation into two separate stages: first forming a conductive polymer-containing layer on the separator surface using a low-viscosity application liquid, then impregnating the wound body with electrolyte solution. This segmentation allows the conductive polymer to be deposited without the viscosity problems that would prevent sufficient impregnation of the wound body interior.
Solution Approach 2:
The conductive polymer layer is formed preliminarily on the separator surface before the wound body is assembled and impregnated with electrolyte solution. This preliminary formation ensures that the conductive polymer is in place without requiring high-viscosity dispersion liquid to penetrate the wound body, thus avoiding the impregnation problems.
2Quantity of substance
If the dielectric film on the anode foil surface is covered by dense conductive polymer particles, then the conductive polymer layer is formed, but the electrolyte solution cannot contact the dielectric layer surface
Solution Approach 1:
The invention creates different local qualities: the outer surface of the conductive polymer layer is kept porous and loose to allow electrolyte solution contact, while the inner layer adjacent to the dielectric film provides the conductive function. This local differentiation ensures both conductive polymer coverage and electrolyte access to the dielectric layer.
Solution Approach 2:
The conductive polymer layer is designed with a porous structure that allows electrolyte solution to penetrate through to the dielectric layer surface. The porous nature prevents the dense coverage problem while maintaining the conductive polymer's electrical functionality.
3Reliability
If conventional manufacturing methods are used, then the conductive polymer layer is formed, but the initial capacity is reduced and ESR increases
Solution Approach 1:
The separator serves as an intermediary carrier for the conductive polymer layer. By forming the conductive polymer layer on the separator rather than directly impregnating the wound body with high-viscosity dispersion liquid, the invention ensures sufficient conductive polymer distribution without the viscosity-related formation problems, thus improving initial capacity and reducing 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 method enables the formation of electrolytic capacitors with excellent characteristics, including improved capacity, reduced ESR, enhanced reliability, and minimized risk of leakage currents and short circuits.
Implementation Method 1
the liquid medium includes water and an organic compound that does not boil at 100° C. under 1 atm, and in step (b), a portion of the liquid medium is removed such that the organic compound remains in the conductive polymer layer
Data Source
AI summary
A disclosed manufacturing method includes, in the following order: a polymer layer formation step of forming a conductive polymer layer containing a conductive polymer component; a stacked body formation step of forming a stacked body including the conductive polymer layer by stacking an anode foil, a cathode foil, and a separator such that the separator is disposed between the anode foil and the cathode foil; and an impregnation step of impregnating the stacked body with a liquid component. The polymer layer formation step includes: a step (a) of applying an application liquid containing the conductive polymer component and a liquid medium to a predetermined surface and the separator; and a step (b) of forming the conductive polymer layer on the predetermined surface and the separator by removing a portion of the liquid medium from the applied application liquid. The liquid medium includes water and an organic compound that does not boil at 100° C. under 1 atm. In the step (b), a portion of the liquid medium is removed such that the organic compound remains in the conductive polymer layer.