Electrolytic Capacitor Solid Electrolyte Layer Shrinkage
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Solution Overview
Problem
Conductive polymer layers in electrolytic capacitors, such as those containing poly(3,4-ethylenedioxythiophene) (PEDOT), tend to shrink during repeated charging and discharging, leading to decreased adhesiveness with the dielectric layer and subsequent capacitance loss.
Innovation Solution
Incorporating a solid electrolyte layer with a combination of first and second conductive polymers, where the mass ratio of the second conductive polymer is higher near the dielectric layer and lower near the cathode lead-out layer, to reduce shrinkage and maintain adhesiveness, using a combination of poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PANI) as preferred conductive polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conductive polymer layer containing PEDOT is used as the solid electrolyte layer, then high capacitance can be achieved, but the conductive polymer layer shrinks during repeated charging and discharging, leading to decreased adhesiveness with the dielectric layer and capacitance loss
Solution Approach 1:
The patent applies composite materials by combining two different conductive polymers (first conductive polymer with thiophene skeleton and second conductive polymer with aniline skeleton) in a layered structure. The solid electrolyte layer comprises both polymers with the second polymer having higher concentration near the dielectric layer and lower concentration near the cathode lead-out layer, creating a composite structure that leverages the complementary properties of each polymer to maintain adhesiveness while providing high capacitance.
Solution Approach 2:
The patent implements local quality by creating a non-uniform distribution of the second conductive polymer within the solid electrolyte layer. The mass ratio of the second conductive polymer is specifically controlled to be higher in the region close to the dielectric layer and lower in the region close to the cathode lead-out layer. This spatial variation in composition optimizes adhesiveness at the critical dielectric interface while maintaining overall capacitance performance.
2Volume of moving object
If the solid electrolyte layer is made thinner to reduce capacitor size, then miniaturization is achieved, but the layer becomes more prone to shrinkage and peeling during operation
Solution Approach 1:
The composite structure of two conductive polymers provides enhanced structural stability even when the overall layer thickness is reduced. The interaction between the thiophene-based and aniline-based polymers creates a more robust network that resists shrinkage and peeling, enabling miniaturization without sacrificing structural integrity.
Solution Approach 2:
By concentrating the second conductive polymer near the dielectric layer interface, the patent strengthens the critical region most susceptible to peeling. This localized reinforcement allows the overall layer to be thinner while maintaining adequate structural stability at the stress-prone interface region.
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 suppresses capacitance decrease during repeated charging and discharging, while maintaining high capacitance and excellent withstand voltage characteristics, by minimizing shrinkage and peeling of the solid electrolyte layer from the dielectric layer.
Implementation Method 1
allowing a first conductive polymer and a second conductive polymer to adhere to an anode body having a dielectric layer formed on a surface of the anode body by bringing a first treatment liquid to contact the anode body
Data Source
AI summary
An electrolytic capacitor includes an anode body, a dielectric layer disposed on the anode body, a solid electrolyte layer disposed on the dielectric layer, and a cathode lead-out layer disposed on the solid electrolyte layer. The solid electrolyte layer contains a first conductive polymer having a thiophene skeleton and a second conductive polymer having an aniline skeleton. In the solid electrolyte layer, a mass ratio of the second conductive polymer with respect to a total mass of the first conductive polymer and the second conductive polymer in a region close to the dielectric layer is greater than a mass ratio of the second conductive polymer with respect to a total mass of the first conductive polymer and the second conductive polymer in a region close to the cathode lead-out layer.