High-temperature-resistant anti-aging conductive polymer solid electrolytic capacitor

Abstract

The application discloses a high-temperature-resistant and anti-aging conductive polymer solid electrolytic capacitor, which comprises core package conductive polymer dispersion liquid one, conductive polymer dispersion liquid two and a dopant, the core is immersed in the conductive polymer dispersion liquid one to form a layer of uniform film which is tightly combined and has high conductivity, then the conductive polymer dispersion liquid two with polyphenylene sulfide and other heat-resistant additives is added to form a multilayer film structure, and finally the dopant solution is immersed to fill the gap between the conductive polymer and the core package and itself. In the application, the conductive polymer dispersion liquid with two different components, the conductive additives such as ethylene glycol and dimethyl sulfoxide, the heat-resistant additives such as polyphenylene sulfide, and the like are added to improve the conductivity of the film, the heat resistance and mechanical properties of the film are improved, and the deterioration caused by external oxygen is effectively inhibited to a certain extent, the two effects are mutually coordinated to avoid the rapid increase of ESR, so that the electrolytic capacitor can maintain high capacity and service life even under high-temperature operation.

Description

Technical Field

[0001] This invention relates to the field of solid electrolytic capacitors, and more particularly to a high-temperature resistant, anti-aging, conductive polymer solid electrolytic capacitor. Background Technology

[0002] Due to rapid development in various fields, electrolytic capacitors are being used more and more widely. An electrolytic capacitor mainly consists of an anode, a dielectric layer, and a cathode. The anode is a metal, and its surface is corroded to form an electrolyte oxide film. The other material in contact with the dielectric is called the cathode, and its properties affect the overall performance of the capacitor.

[0003] Liquid electrolytic capacitors use an ion-conducting electrolyte as the actual cathode, resulting in low conductivity and a high risk of explosion during use, posing a safety hazard. Gradually, solid-state electrolytic capacitors have replaced liquid electrolytic capacitors, gaining a dominant market share. The latest solid-state electrolytic capacitors use PEDOT or PEDOT:PSS films as the solid electrolyte, achieving conductivity close to that of a conductor while maintaining high stability.

[0004] In high-temperature operating environments, PEDOT decomposes due to its inherent instability and reduced conductivity upon heating. Simultaneously, gaps exist between the solid electrolyte and the dielectric layer, the cathode foil, and between the cathode foil and the casing. Furthermore, the casing's sealing layer develops defects such as pinholes, pull-outs, and penetrations over time. This significantly accelerates the deterioration of the solid electrolyte layer due to external oxygen, increasing the device's ESR, leading to rapid capacitance decay, reduced lifespan, and a high failure rate for the electrolytic capacitor. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature resistant, anti-aging, conductive polymer solid electrolytic capacitor, which solves the problems of existing solid electrolytic capacitors being unable to withstand high temperatures and having a high scrap rate.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-temperature resistant, anti-aging, conductive polymer solid electrolytic capacitor, comprising a core, a conductive polymer dispersion I, a conductive polymer dispersion II, and a dopant; The conductive polymer dispersion comprises EDOT monomer, an aqueous solution of polystyrene sulfonic acid with a molecular weight of ~75000, an oxidant, and a conductive additive, wherein the weight ratio of EDOT monomer, conductive additive, and oxidant is 30~35:6~30:35~40. The conductive polymer dispersion II includes EDOT monomer, an aqueous solution of polystyrene sulfonic acid with a molecular weight of ~75000, an oxidant, and a heat-resistant additive. The weight ratio of EDOT monomer, heat-resistant additive, and oxidant is 30~35:42~54:35~40.

[0007] A further improvement of the present invention is that its preparation method includes the following steps: A. Add EDOT monomer to a polystyrene sulfonic acid aqueous solution to form a monomer solution; B. Add conductive additives and oxidants to the monomer solution to form conductive polymer dispersion one, for later use; C. Repeat step A, add heat-resistant additives and oxidants to the monomer solution to form conductive polymer dispersion II, for later use; D. Impregnate the core with the conductive polymer dispersion obtained in step B, and then dry it; E. Impregnate the core obtained in step D with the conductive polymer dispersion obtained in step C, and then dry it. F. The core obtained in step E is impregnated with a dopant and then dried.

[0008] A further improvement of the present invention is that: the core package is composed of an anode foil, a dielectric layer and a cathode foil, wherein the dielectric layer refers to an insulating oxide layer obtained by oxidizing the anode foil; the conductive polymer layer is contained within the conductive polymer layer by impregnating it with a conductive polymer dispersion; heat-resistant additives and oxidants are added to a portion of the conductive polymer layer to form a heat-resistant and enhanced conductive polymer layer; and a dopant layer is impregnated in a portion of the heat-resistant and enhanced conductive polymer layer to form a dopant layer.

[0009] A further improvement of the present invention is that the conductive additive is composed of at least one of ethylene glycol and dimethyl sulfoxide.

[0010] A further improvement of the present invention is that the heat-resistant additive is composed of at least one of polyphenylene sulfide and polyimide materials.

[0011] A further improvement of the present invention is that, in the conductive polymer dispersion, the weight ratio of EDOT monomer, conductive additive, and oxidant is 30:6:35. A further improvement of the present invention is that the weight ratio of EDOT monomer, heat-resistant additive and oxidant in the conductive polymer dispersion II is 30:42:35.

[0012] A further improvement of the present invention is that the dopant solute includes any one or more of organic acids and ammonium salts of inorganic acids, and the solvent is any one or a combination of two or more of methanol, ethylene glycol, triethylamine, tributylamine and sulfolane.

[0013] A further improvement of the present invention is that the dopant solute is an ammonium salt combination of phthalic acid and pyromellitic acid, and the solvent is a combination of triethylamine, ethylene glycol and sulfolane.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention utilizes two conductive polymer dispersions. First, a PEDOT:PSS film with good conductivity and tight bonding to the core is formed by impregnating conductive polymer dispersion one. Then, conductive polymer dispersion two is impregnated to form a polymer film with high-temperature resistance. The presence of high-temperature resistant additives such as polyphenylene sulfide (PPS) enhances the mechanical properties and high-temperature resistance of the film and effectively inhibits oxygen-induced deterioration. In particular, PPS's conductivity increases after oxidation by oxygen, further reducing the impact of oxygen on ESR. Conductive polymer dispersions one and two exhibit good stability and high solid content, resulting in good mechanical properties, heat resistance, and conductivity after film formation. Furthermore, the presence of dopants improves voltage withstand capability. The preparation process of this invention is simple, easy to operate, and highly controllable. It effectively mitigates oxygen-induced deterioration and high-temperature-induced decomposition, making it suitable for large-scale production. This improves the temperature resistance and safety of the prepared conductive polymer solid-state electrolytic capacitors and reduces the scrap rate. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the present invention; The numbers in the diagram are: 1-Anode foil; 2-Dielectric layer; 3-Conductive polymer layer; 4-Heat-resistant reinforced conductive polymer layer; 5-Dopant layer; 6-Cathode foil. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] This embodiment provides a technical solution:

[0019] Example a

[0020] A high-temperature resistant, anti-aging, conductive polymer solid-state electrolytic capacitor comprises a core, a first conductive polymer dispersion, a second conductive polymer dispersion, and dopants. The first conductive polymer dispersion includes EDOT monomer, an aqueous solution of polystyrene sulfonic acid with a molecular weight of ~75,000, conductive additives, and an oxidant, with a weight ratio of 30:6:35. The second conductive polymer dispersion includes EDOT monomer, an aqueous solution of polystyrene sulfonic acid with a molecular weight of ~75,000, heat-resistant additives, and an oxidant, with a weight ratio of 30:42:35. The conductive additive is dimethyl sulfoxide, and the heat-resistant additive is polyphenylene sulfide or polyimide. The oxidant is selected from potassium persulfate. Dopants include pyromellitic acid, ammonium salts of phthalic acid, triethylamine, ethylene glycol, and sulfolane.

[0021] Example b

[0022] A conductive polymer-based solid electrolytic capacitor comprises a core, a first conductive polymer dispersion, a second conductive polymer dispersion, and dopants. The first conductive polymer dispersion includes EDOT monomer, an aqueous solution of polystyrene sulfonic acid with a molecular weight of ~75,000, conductive additives, and an oxidant, with a weight ratio of 30:15:35. The second conductive polymer dispersion includes EDOT monomer, an aqueous solution of polystyrene sulfonic acid with a molecular weight of ~75,000, heat-resistant additives, and an oxidant, with a weight ratio of 30:45:35. The conductive additive is dimethyl sulfoxide, and the heat-resistant additive is polyphenylene sulfide or polyimide. The oxidant is selected from potassium persulfate. Dopants include pyromellitic acid, ammonium salts of phthalic acid, triethylamine, ethylene glycol, and sulfolane.

[0023] Example c

[0024] A conductive polymer-based solid electrolytic capacitor comprises a core, a first conductive polymer dispersion, a second conductive polymer dispersion, and dopants. The first conductive polymer dispersion comprises EDOT monomer, an aqueous solution of polystyrene sulfonic acid with a molecular weight of ~75,000, conductive additives, and an oxidant, with a weight ratio of EDOT monomer, conductive additive, and oxidant of 30:30:35. The second conductive polymer dispersion comprises EDOT monomer, an aqueous solution of polystyrene sulfonic acid with a molecular weight of ~75,000, heat-resistant additives, and an oxidant, with a weight ratio of EDOT monomer, heat-resistant additive, and oxidant of 30:54:35. The conductive additive is dimethyl sulfoxide, and the heat-resistant additive is polyphenylene sulfide or polyimide. The oxidant is selected from potassium persulfate. Dopants include pyromellitic acid, ammonium salts of phthalic acid, triethylamine, ethylene glycol, and sulfolane.

[0025] This invention utilizes two conductive polymer dispersions. First, a PEDOT:PSS film with good conductivity and tight bonding to the core is formed by impregnating with conductive polymer dispersion one. Then, a second conductive polymer dispersion is impregnated to form a polymer film with high-temperature resistance. The presence of high-temperature resistant additives such as polyphenylene sulfide (PPS) enhances the mechanical properties and high-temperature resistance of the film and effectively inhibits oxygen-induced deterioration. In particular, PPS's conductivity increases after oxidation by oxygen, further reducing its impact on ESR. The conductive polymer dispersions have high solid content and high stability. The synergistic effect of the heat-resistant additives improves the mechanical properties and heat resistance of the film after formation. Further doping of the film with dopants enhances its voltage withstand capability to a certain extent. This invention features a simple, easy-to-operate, and highly controllable preparation process, suitable for large-scale production. It improves the temperature resistance and safety of the prepared conductive polymer solid-state electrolytic capacitors and reduces the scrap rate.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, products, or apparatus.

[0028] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0029] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art. In the drawings, for clarity, the thickness of layers and regions may be exaggerated, and the same reference numerals are used to denote the same devices, and therefore their description will be omitted.

[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-temperature resistant, anti-aging, conductive polymer solid electrolytic capacitor, characterized in that, Its preparation method includes the following steps: A. Add EDOT monomer to a polystyrene sulfonic acid aqueous solution to form a monomer solution; B. Add conductive additives and oxidants to the monomer solution to form conductive polymer dispersion one, for later use; C. Repeat step A, add heat-resistant additives and oxidants to the monomer solution to form conductive polymer dispersion II, for later use; D. Impregnate the core with the conductive polymer dispersion obtained in step B, and then dry it; E. Impregnate the core obtained in step D with the conductive polymer dispersion obtained in step C, and then dry it. F. The core obtained in step E is impregnated with a dopant and then dried. The conductive polymer dispersion comprises EDOT monomer, an aqueous solution of polystyrene sulfonic acid with a molecular weight of ~75000, an oxidant, and a conductive additive, wherein the weight ratio of the EDOT monomer, the conductive additive, and the oxidant is 30-35:6-30:35-40. The conductive polymer dispersion II comprises EDOT monomer, an aqueous solution of polystyrene sulfonic acid with a molecular weight of ~75000, an oxidant, and a heat-resistant additive, wherein the weight ratio of the EDOT monomer, the heat-resistant additive, and the oxidant is 30-35:42-54:35-40. The conductive additive is composed of at least one of ethylene glycol and dimethyl sulfoxide; The heat-resistant additive is a polyphenylene sulfide; The dopant solute includes any one or more of the ammonium salts of organic acids and the ammonium salts of inorganic acids, and the solvent is any one or a combination of two or more of methanol, ethylene glycol, triethylamine, tributylamine and sulfolane.

2. The method for preparing a high-temperature resistant, anti-aging, conductive polymer solid electrolytic capacitor according to claim 1, characterized in that: The core is composed of an anode foil (1), a dielectric layer (2) and a cathode foil (6). It contains a conductive polymer layer (3) by impregnating it with a conductive polymer dispersion. Heat-resistant additives and oxidants are added to part of the conductive polymer layer (3) to form a heat-resistant and enhanced conductive polymer layer (4). Part of the heat-resistant and enhanced conductive polymer layer (4) is impregnated with dopants to form a dopant layer (5).

3. The method for preparing a high-temperature resistant, anti-aging, conductive polymer solid electrolytic capacitor according to claim 1, characterized in that: In the first conductive polymer dispersion, the weight ratio of the EDOT monomer, the conductive additive, and the oxidant is 30:6:

35.

4. The high-temperature resistant, anti-aging, conductive polymer solid electrolytic capacitor according to claim 1, characterized in that: In the second conductive polymer dispersion, the weight ratio of the EDOT monomer, the heat-resistant additive, and the oxidant is 30:42:

35.

5. The method for preparing a high-temperature resistant, anti-aging, conductive polymer solid electrolytic capacitor according to claim 1, characterized in that: The dopant solute is an ammonium salt combination of phthalic acid and pyromellitic acid, and the solvent is a combination of triethylamine, ethylene glycol and sulfolane.

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