Solid Electrolytic Capacitor Layering for Leakage and Withstand Voltage
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Solution Overview
Problem
Solid electrolytic capacitors face challenges with low film repairability of the dielectric layer, leading to leakage currents and limited withstand voltage properties.
Innovation Solution
A solid electrolytic capacitor element with a porous anode body, a dielectric layer, and a cathode portion featuring a solid electrolyte layer containing an ionic liquid. The solid electrolyte layer is structured with multiple sub-layers, including a first solid electrolyte with a self-doped conductive polymer and subsequent sub-layers with conductive polymers, optimized for ionic liquid distribution across interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a liquid dispersion containing conductive polymer particles is used to form the solid electrolyte layer, then the ease of manufacture is improved and the thickness can be easily increased, but the dielectric layer has low film repairability leading to leakage current
Solution Approach 1:
An ionic liquid layer is introduced as an intermediary substance between the dielectric layer and the solid electrolyte layer. This ionic liquid layer serves as a mediator that can repair defects in the dielectric layer, preventing leakage current while allowing the use of liquid dispersion for easy manufacturing of the solid electrolyte layer.
Solution Approach 2:
The capacitor employs a composite structure combining multiple materials: the dielectric layer, the ionic liquid layer, and the solid electrolyte layer containing conductive polymer particles. This composite structure allows each layer to perform its specific function, with the ionic liquid layer providing film repairability while the solid electrolyte layer provides ease of manufacture and adjustable thickness.
2Strength
If the solid electrolyte layer is made thicker to enhance withstand voltage properties, then the withstand voltage properties are improved, but the leakage current increases due to low film repairability
Solution Approach 1:
The ionic liquid layer acts as a mediator that repairs dielectric defects, enabling the solid electrolyte layer to be made thicker for enhanced withstand voltage properties without the accompanying increase in leakage current that would normally occur.
3Reliability
If chemical polymerization or electropolymerization is used to form the solid electrolyte layer, then precise control of polymerization reaction is required, but this increases the complexity of the manufacturing process
Solution Approach 1:
The patent extracts the polymerization step from the manufacturing process by using pre-formed conductive polymer particles in a liquid dispersion. This eliminates the need for precise control of chemical polymerization or electropolymerization reactions, significantly simplifying the manufacturing process while maintaining solid electrolyte layer quality.
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 approach effectively suppresses leakage currents and enhances withstand voltage properties by improving film repairability and resistance of the solid electrolyte layer, while maintaining low equivalent series resistance (ESR) and high electrostatic capacity.
Implementation Method 1
The solid electrolyte layer is formed through, for example, chemical polymerization, electropolymerization, or the like
Implementation Method 2
The solid electrolyte layer is formed through, for example, chemical polymerization, electropolymerization, or the like
Implementation Method 3
the solid electrolyte layer contains an ionic liquid, and includes a first solid electrolyte that covers at least a portion of the dielectric layer and a second solid electrolyte layer that covers at least a portion of the first solid electrolyte
Implementation Method 4
an anode body that includes a porous portion at least at a surface layer of the anode body
Data Source
AI summary
Disclosed is a capacitor element including: an anode body; a dielectric layer; and a cathode portion that includes a solid electrolyte layer and a cathode lead-out layer. The solid electrolyte layer contains an ionic liquid, and includes a first solid electrolyte and a second solid electrolyte layer. The first solid electrolyte contains a self-doped conductive polymer. The second solid electrolyte layer includes: a solid electrolyte 2A; a solid electrolyte 2B; and a solid electrolyte 2C. Out of a first interface between the first solid electrolyte and the solid electrolyte 2A, a second interface between the solid electrolyte 2A and the solid electrolyte 2B, a third interface between the solid electrolyte 2B and the solid electrolyte 2C, and a fourth interface between the solid electrolyte 2C and the cathode lead-out layer, the second interface or the third interface has a largest distribution amount of the ionic liquid.