Polymer Capacitor Electrolyte Process for ESR and Capacitance Stability
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Solution Overview
Problem
The electrical properties of capacitors, particularly those with solid electrolyte layers based on PEDOT/PSS, deteriorate over time due to switch-on and switch-off processes and elevated temperatures, leading to unstable capacitance and high equivalent series resistance (ESR).
Innovation Solution
A process for manufacturing capacitors involving the introduction of a conductive polymer dispersion with a low conductivity into a porous electrode body, followed by partial removal of the dispersing agent and impregnation with a high-boiling solvent, which is then encapsulated and heated to stabilize the electrolyte layer, reducing the evaporation of the impregnation solution and maintaining its presence within the capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PEDOT/PSS dispersion is applied to the oxide layer and the dispersion medium is removed by evaporation, then the solid electrolyte layer is formed, but the electrical properties deteriorate over time due to switch-on and switch-off processes and elevated temperatures
Solution Approach 1:
The patent changes the physical and chemical parameters of the electrolyte system by replacing volatile dispersion media with non-volatile ionic liquids and adjusting the polymer composition. This parameter change ensures the electrolyte maintains its properties over time and under temperature variations, resolving the reliability deterioration issue
Solution Approach 2:
The patent replaces the unstable, short-lived PEDOT/PSS dispersion with a more stable ionic liquid-based electrolyte system that maintains its functional properties throughout the capacitor's service life, effectively extending the operational durability of the solid electrolyte
2Reliability
If multiple process steps are used to manufacture the capacitor, then the electrical properties are improved, but the manufacturing complexity increases
Solution Approach 1:
The patent combines multiple process steps into a single integrated procedure: the porous electrode body is directly impregnated with the ionic liquid-containing polymer solution, and the ionic liquid serves both as solvent and functional electrolyte component. This merging eliminates intermediate evaporation and impregnation steps while maintaining capacitance stability
Solution Approach 2:
The ionic liquid serves multiple functions simultaneously: it acts as a dispersing medium for the conductive polymer, provides ionic conductivity for the electrolyte function, and prevents polymer degradation. This multi-functionality reduces the need for separate process steps and materials
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 process results in capacitors with stable electrical properties over a long period, minimal capacitance change, and low ESR, even at elevated temperatures, while simplifying the manufacturing process with fewer steps.
Implementation Method 1
a liquid composition A, B or C is introduced into at least a part of the porous electrode body
Implementation Method 2
the porous electrode body is removed from the liquid composition used in process step b) and is subsequently dried, wherein the drying preferably takes place at a temperature in a range from 20°C to 200°C
Implementation Method 3
at least a part of the pores of the porous electrode body obtained in process step c) is filled with an impregnation solution comprising at least one impregnation solvent
Implementation Method 4
the encapsulated electrode body obtained in process step e) is heated at a temperature of higher than 50°C, more preferably of higher than 75°C and even more preferably of higher than 100°C for more than 10 minutes
Data Source
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AI summary
The present invention relates to a process for manufacturing a capacitor, comprising the process steps: a) provision of a porous electrode body (1) made of an electrode material (2), wherein a dielectric (3) at least partially covers a surface of this electrode material (2); b) introduction of a liquid composition which comprises an electrically conductive polymer and a dispersing agent into at least a part of the porous electrode body (1) provided in process step a), wherein a conductive layer made from the liquid composition has a conductivity of less than 100 S/cm; c) at least partial removal of the dispersing agent from the porous electrode body (1) obtained in process step b) for the formation of a solid electrolyte layer (4) that at least partially covers a surface of the dielectric (3); d) filling at least a part of the pores (5) of the porous electrode body (1) obtained in process step c) with an impregnation solution comprising at least one impregnation solvent, wherein the at least one impregnation solvent has a boiling point (determined at 1013 hPa) of at least 150°C; e) encapsulation of the porous electrode body (1) obtained in process step d); f) heating the encapsulated electrode body obtained in process step e) at a temperature of higher than 50°C for more than 10 minutes. The invention also relates to capacitor manufactured with this process, to the use of an electrolytic capacitor and to electronic circuits.