Polymer Capacitor Solid Electrolyte Formation via Solvent Parameter Optimization
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Solution Overview
Problem
Existing electrolytic capacitors, particularly aluminum capacitors, face challenges in maintaining high breakdown voltage while minimizing capacitance reduction at low temperatures, which is critical for automotive industry applications, and previous methods like adding ion-conducting substances or impregnating with certain solvents lead to undesirable performance issues such as capacitance loss and volatility.
Innovation Solution
A method involving a porous electrode body coated with a dielectric and treated with a liquid composition containing a high-boiling solvent and electrically conductive polymer, followed by impregnation with a solvent having a hydroxy group, to form a solid electrolyte, which is then encapsulated, optimizing the capacitor's performance for both high and low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion-conducting substances like polyethylene glycols are added to polymer dispersions to increase breakdown voltage, then the breakdown voltage is improved, but the capacitance decreases strongly at low temperatures
Solution Approach 1:
The patent changes the chemical parameters of the solvent system by selecting specific solvents with defined boiling points (150-275°C) and molecular weights (70-180 g/mol) that contain hydroxy groups. This parameter optimization allows the solid electrolyte to achieve high breakdown voltage without the strong capacitance loss at low temperatures that occurs with polyethylene glycol additives.
Solution Approach 2:
The patent creates a composite solid electrolyte system combining conductive polymers with specifically selected solvent molecules. The composite structure of the solid electrolyte layer, formed by controlled solvent removal, integrates the conductive polymer matrix with the optimized solvent system, achieving both high breakdown voltage and stable capacitance across temperature ranges.
2Quantity of substance
If solvents like γ-butyrolactone or sulfolane are used to increase capacitance yield, then the capacitance is improved, but the components volatilise at elevated temperatures causing drying-out
Solution Approach 1:
The patent optimizes the boiling point parameter of the solvent to be between 150°C and 275°C, which is high enough to prevent volatilization during normal capacitor operation and manufacturing processes, yet low enough to allow complete removal during the solid electrolyte formation process. This parameter selection resolves the contradiction between maintaining capacitance yield and ensuring thermal stability.
Solution Approach 2:
The patent applies different quality requirements to different stages of the process: during capacitor operation, the solvent provides high capacitance yield, while during the solid electrolyte formation stage, the solvent is completely removed. The local quality of the solvent system is optimized for each stage, with the final solid electrolyte structure providing long-term thermal stability.
3Reliability
If the breakdown voltage is increased for high operating voltages, then the reliability is improved, but the capacitance decreases at low temperatures
Solution Approach 1:
The patent changes the physical and chemical parameters of the solvent system, specifically selecting solvents with boiling points of 150-275°C and molecular weights of 70-180 g/mol that contain hydroxy groups. These parameter changes enable the solid electrolyte to achieve high breakdown voltage while maintaining stable capacitance at low temperatures, unlike previous approaches using polyethylene glycol additives.
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 method achieves a minimal capacitance decrease at low temperatures and ensures long-term stability at high temperatures, meeting industry requirements with a simplified manufacturing process, and the capacitors exhibit reduced capacitance loss over time.
Implementation Method 1
introduction of a liquid composition, preferably a liquid composition in the form of a dispersion or solution, more preferably a liquid composition in the form of a dispersion, which comprises an electrically conductive polymer, at least one high-boiling solvent having a boiling point (determined at 1013.25 hPa) of at least 150°C and of not more than 275°C and optionally a dispersing agent, preferably water, into at least a part of the porous electrode body provided in process step a) and at least partial removal of the high-boiling solvent and, if present, of the dispersing agent for the formation of a solid electrolyte
Implementation Method 2
c) filling at least a part of the pores of the porous electrode body obtained in process step b) with an impregnation solution comprising at least one impregnation solvent, wherein the at least one impregnation solvent comprises at least one hydroxy group and has a molecular weight in the range from 70 to 180 g/mol
Data Source
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AI summary
The present invention relates to a method for manufacturing a capacitor, comprising the method 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, at least one high-boiling solvent having a boiling point (determined at 1013.25 hPa) of at least 150°C and of not more than 275°C and optionally a dispersing agent into at least a part of the porous electrode body (1) provided in process step a) and at least partial removal of the high-boiling solvent and, if present, of the dispersing agent for the formation of a solid electrolyte (4) that at least partially covers a surface of the dielectric (3); c) filling at least a part of the pores of the porous electrode body (1) obtained in process step b) with an impregnation solution (6) comprising at least one impregnation solvent, wherein the at least one impregnation solvent comprises at least one hydroxy group and has a molecular weight in the range from 70 to 180 g/mol; d) encapsulation of the porous electrode body (1) obtained in process step c). The invention also relates to capacitor manufactured with this method, the use of an electrolytic capacitor and electronic circuits.