Cathode Lead-Out Layer Composition for Low-ESR Electrolytic Capacitors
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Solution Overview
Problem
Existing electrolytic capacitors face insufficient reduction in equivalent series resistance (ESR) at high temperatures due to deterioration of conductive polymers in the solid electrolyte layer, primarily caused by air permeation through the carbon layer in the cathode lead-out layer.
Innovation Solution
Incorporating a carbon material with a first polymer containing an acid group, such as a sulfone or carboxyl group, into the cathode lead-out layer to enhance adhesion with the conductive polymer and improve the gas barrier properties, thereby reducing air permeation and maintaining low ESR even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a carbon layer is used in the cathode lead-out layer, then electrical conductivity is improved, but gas barrier properties deteriorate due to air permeation
Solution Approach 1:
The cathode lead-out layer is constructed as a composite material containing both carbon material (for electrical conductivity) and a polymer with acid groups (for gas barrier properties). This composite structure allows simultaneous achievement of high electrical conductivity and effective air permeation prevention, resolving the contradiction between these two opposing requirements.
2Ease of manufacture
If the carbon layer structure is simplified, then manufacturing complexity is reduced, but adhesion with solid electrolyte layer deteriorates
Solution Approach 1:
The invention changes the chemical parameters of the cathode lead-out layer by incorporating polymers with specific acid functional groups (sulfone, carboxyl, or derivative groups). This parameter change enhances chemical adhesion to the solid electrolyte layer without complicating the manufacturing process, as the polymer can be applied in existing production lines.
3Device complexity
If conventional carbon layer is used, then device complexity is kept simple, but ESR increases at high temperatures due to polymer deterioration
Solution Approach 1:
The invention uses a polymer layer with acid groups that provides protective function against air permeation and polymer deterioration. This relatively simple additive layer prevents the main conductive polymer from deteriorating at high temperatures, thereby maintaining low ESR without significantly increasing device complexity.
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 enhanced adhesion and gas barrier properties effectively suppress the increase in ESR, ensuring the electrolytic capacitor's performance in high-temperature environments.
Implementation Method 1
The cathode lead-out layer contains a carbon material and a first polymer including an acid group. And the acid group includes at least one selected from the group consisting of a sulfone group, a carboxyl group, and a derivative of the sulfone group or the carboxyl group.
Implementation Method 2
air (particularly oxygen, or oxygen and moisture) easily enters inside the electrolytic capacitor by permeating the exterior body. When the air that has entered the electrolytic capacitor comes into contact with the solid electrolyte layer, a conductive polymer contained in the solid electrolyte layer may deteriorate.
Data Source
AI summary
An electrolytic capacitor includes a capacitor element. The capacitor element includes an anode body, a dielectric layer that covers at least a part of the anode body, a solid electrolyte layer that covers at least a part of the dielectric layer, and a cathode lead-out layer that covers a part of the solid electrolyte layer. The cathode lead-out layer contains a carbon material and a first polymer including an acid group. The acid group includes at least one selected from the group consisting of a sulfone group, a carboxyl group, and a derivative of the sulfone group or the carboxyl group.