Conductive Polymer Monomer Liquid for Low-Leak Capacitors
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Solution Overview
Problem
Conductive polymer-based electrolyte capacitors face issues with inferior heat resistance and high leak current due to residual iron and the instability of ammonium persulfate-based oxidant solutions, which also lead to reduced capacitance and storage challenges.
Innovation Solution
A monomer liquid dispersing naphthalene sulfonic acid or benzene sulfonic acid heterocyclic compounds without hydroxyl groups is used for conductive polymer production, combined with a non-iron salt oxidant like ammonium persulfate, to enhance heat resistance and reduce leak current, allowing for improved capacitor performance and storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ferric salts of aromatic sulfonic acid are used as oxidant and dopant, then the chemical oxidation polymerization process is simple and suitable for industrialization, but the heat resistance is inferior and leak current is large due to residual iron in the conductive polymer
Solution Approach 1:
The invention extracts and removes the harmful iron component from the polymerization system by replacing ferric salts with non-iron oxidants (ammonium persulfate, sodium persulfate, or potassium persulfate). This extraction of the harmful element resolves the contradiction by eliminating residual iron contamination while maintaining the polymerization process efficiency.
Solution Approach 2:
The invention changes the chemical parameter of the oxidant from iron-based (ferric salts) to non-iron-based (ammonium/sodium/potassium persulfate). This parameter change fundamentally alters the composition of the conductive polymer, removing iron residues and thereby improving heat resistance and reducing leak current while preserving electrical conductivity.
2Reliability
If ammonium persulfate aqueous solution is mixed with butylamine phenolsulfonate aqueous solution to serve as oxidant and dopant agent, then heat resistance is improved and leak current is reduced, but ammonium persulfate deteriorates over time requiring immediate use and increasing disposal costs
Solution Approach 1:
The invention segments the oxidant and dopant into separate solutions that are prepared and stored independently. The oxidant solution (ammonium persulfate) and dopant solution (naphthalenesulfonic acid heterocyclic compound or benzenesulfonic acid heterocyclic compound without hydroxyl group) are kept separate to prevent premature reaction and deterioration, allowing stable storage and flexible combination before use.
Solution Approach 2:
The dopant is pre-loaded into the capacitor element before the oxidant is added. This preliminary action allows the dopant to be in position and ready, while the oxidant solution is added later to initiate polymerization. This sequence prevents the oxidant from deteriorating before use and ensures optimal performance.
3Duration of action of stationary object
If dopant solution and oxidant solution are prepared separately to improve preservation properties, then storage stability is improved, but the dopant and oxidant react on the capacitor element surface forming salt that reduces capacitance
Solution Approach 1:
The dopant (naphthalenesulfonic acid heterocyclic compound or benzenesulfonic acid heterocyclic compound without hydroxyl group) is pre-impregnated into the capacitor element before the oxidant solution is added. This preliminary action ensures the dopant is distributed throughout the element interior, preventing surface-only reaction and salt formation that would reduce capacitance.
Solution Approach 2:
The capacitor element structure itself acts as an intermediary medium that facilitates the controlled interaction between dopant and oxidant. By pre-loading the dopant into the element's porous structure and then adding the oxidant solution, the reaction occurs throughout the element interior rather than forming a surface salt layer, thereby maintaining high capacitance.
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 solution results in electrolyte capacitors with low ESR, superior heat resistance, and reliable preservation properties, maintaining performance even after storage, while avoiding the drawbacks of iron-based systems and unstable oxidant solutions.
Implementation Method 1
the conductive polymer has such a high conductivity that it is used as an electrolyte of solid electrolyte capacitors... obtained by applying chemical oxidation polymerization or electrolytic oxidation polymerization to polymeric monomers
Implementation Method 2
As an oxidant, a transition metal is used. In particular, it is said that ferric compound is suitable... an oxidant of a non-iron salt type is considered. For example, it was reported to use one which has mixed ammonium persulfate aqueous solution
Data Source
AI summary
There is provided a monomer liquid for conductive polymer production, comprising: at least one monomer selected from the group consisting of thiophene or its derivatives, pyrrole or its derivative and aniline or its derivative; and at least one kind selected from the group consisting of a naphthalene sulfonic acid type heterocyclic compound and a benzene sulfonic acid type heterocyclic compound in which no hydroxyl group is directly connected to the benzene ring, wherein said at least one kind is dispersed in said at least one monomer. Also, there is provided a production of an electrolyte capacitor by using the monomer liquid for conductive polymer production is explained. In particular, imidazoles are favorable as the naphthalene sulfonic acid type heterocyclic compound and the benzene sulfonic acid type heterocyclic compound.