A high-stability solid-state aluminum electrolytic capacitor and a method for manufacturing the same

Abstract

A high-stability solid-state aluminum electrolytic capacitor includes a casing, a core, and a rubber stopper. The core is sealed inside the casing by the rubber stopper. A conductive polymer film is formed inside the core, comprising a first conductive polymer layer and a second conductive polymer layer. The first conductive polymer layer comprises sulfonated polyetheretherketone (PEDOT):PSS, and the second conductive polymer layer comprises PEDOT:PSS. In this invention, the introduction of polyetheretherketone improves the adhesion between PEDOT:PSS and the anode foil, thereby enhancing the cycle stability of the solid-state aluminum electrolytic capacitor.

Description

Technical Field

[0001] This invention relates to an aluminum electrolytic capacitor, and more particularly to a high-stability solid aluminum electrolytic capacitor and its preparation method. Background Technology

[0002] Currently, solid aluminum electrolytic capacitors, because they do not contain electrolyte, eliminate the risks of leakage and capacitor fire caused by valve opening, giving them a significant advantage in widespread application. The electrolyte in solid aluminum electrolytic capacitors is typically PEDOT or PEDOT:PSS. During the charge-discharge cycles of aluminum electrolytic capacitors, PEDOT or PEDOT:PSS continuously expands and contracts, potentially causing the conductive polymer to peel off from the anode foil surface, leading to a sharp decrease in capacitance. Simultaneously, the presence of water molecules in the conductive polymer, when electrolyzed to produce oxygen molecules, accelerates the oxidation and peeling of the conductive polymer from the anode foil surface. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a high-stability solid aluminum electrolytic capacitor and its preparation method.

[0004] To solve the above-mentioned technical problems, the technical solution proposed by the present invention is as follows: 1. A high-stability solid aluminum electrolytic capacitor, comprising a shell, a core, and a rubber stopper, wherein the core is sealed inside the shell by the rubber stopper, and a conductive polymer film is formed inside the core, wherein the conductive polymer film comprises a first conductive polymer layer and a second conductive polymer layer; the first conductive polymer layer comprises sulfonated polyether ether ketone doped PEDOT:PSS, and the second conductive polymer layer comprises PEDOT:PSS.

[0005] Preferably, in the aforementioned high-stability solid aluminum electrolytic capacitor, the first conductive polymer layer is located between the anode foil and the second conductive polymer layer.

[0006] In the aforementioned high-stability solid aluminum electrolytic capacitor, preferably, the weight of sulfonated polyether ether ketone in the first conductive polymer layer accounts for 5%-20% of the total weight of the first conductive polymer layer.

[0007] Preferably, in the aforementioned high-stability solid aluminum electrolytic capacitor, the molar ratio of PEDOT:PSS in the first conductive polymer layer and the second conductive polymer layer is 4:1.

[0008] A method for preparing a high-stability solid aluminum electrolytic capacitor includes the following steps;

[0009] 1) Prepare sulfonated polyether ether ketone for later use;

[0010] 2) Add the sulfonated polyether ether ketone prepared in step 1) to the PEDOT:PSS dispersion and disperse evenly to form a first conductive polymer dispersion; the weight of the sulfonated polyether ether ketone is 5%-20% of the total weight of the sulfonated polyether ether ketone and PEDOT:PSS.

[0011] 3) The core package is impregnated with the first conductive polymer dispersion of PEDOT:PSS from step 2); after drying, a first conductive polymer layer is formed inside the core package;

[0012] 4) The core package that has completed step 3) is impregnated with the second conductive polymer dispersion, and after drying, a second conductive polymer layer is formed inside the core package; the solute in the second conductive polymer dispersion includes PEDOT:PSS;

[0013] 5) Assemble the core package that has completed step 4).

[0014] In the above-mentioned method for preparing a high-stability solid aluminum electrolytic capacitor, preferably, in step 2), the weight concentration of PEDOT:PSS in the first conductive polymer dispersion is 0.5%-5%; and the weight of sulfonated polyether ether ketone accounts for 5%-20% of the total weight of sulfonated polyether ether ketone and PEDOT:PSS.

[0015] In the above-mentioned method for preparing a high-stability solid aluminum electrolytic capacitor, preferably, the weight concentration of PEDOT:PSS in the second conductive polymer dispersion in step 4) is 0.5%-5%.

[0016] In the above-described method for preparing a high-stability solid aluminum electrolytic capacitor, preferably, the core is impregnated with a polar solution before step 3), the polar solution comprising one or more of methanol, ethanol, ethylene glycol, propylene glycol, and DMF.

[0017] The above-mentioned method for preparing a highly stable solid aluminum electrolytic capacitor, preferably, includes the following steps in the preparation method of sulfonated polyether ether ketone;

[0018] ① Keep the polyetheretherketone particles at a temperature of 100-200℃ for more than 12 hours, and protect them with nitrogen gas throughout the process;

[0019] ② Add the polyetheretherketone granules obtained in step ① to concentrated sulfuric acid and stir magnetically for more than 12 hours, keeping the temperature between 50-80℃; the weight ratio of polyetheretherketone granules to concentrated sulfuric acid is 1:15-1:25.

[0020] ③ Reduce the temperature of the mixed solution in step ② to 1-5℃, and wash the precipitated sulfonated polyether ether ketone particles with deionized water until the pH of the washing solution reaches 6-7.

[0021] Compared with the prior art, the advantages of the present invention are: in the present invention, the introduction of polyetheretherketone can improve the adhesion between PEDOT:PSS and the anode foil, thereby improving the cycle stability performance of the solid aluminum electrolytic capacitor. Detailed Implementation

[0022] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0023] It should be noted that when a component is described as being "fixed to, attached to, connected to or connected to" another component, it can be directly fixed to, attached to, connected to or connected to the other component, or it can be indirectly fixed to, attached to, connected to or connected to the other component through other intermediate connectors.

[0024] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0025] A high-stability solid-state aluminum electrolytic capacitor includes a casing, a core, and a rubber stopper. The core is sealed inside the casing by the rubber stopper. A conductive polymer film is formed inside the core, comprising a first conductive polymer layer and a second conductive polymer layer. The first conductive polymer layer comprises sulfonated polyether ether ketone (PEDOT):PSS, and the second conductive polymer layer comprises PEDOT:PSS. In this invention, the addition of sulfonated PEDOT:PSS to the first conductive polymer layer enhances the adhesion between PEDOT:PSS and the anode foil, thereby improving the cycle stability of the solid-state aluminum electrolytic capacitor.

[0026] In this invention, the molar ratio of PEDOT to PSS in the first conductive polymer layer and the second conductive polymer layer is 4:1; in the PEDOT:PSS, every 4 moles of PEDOT are doped with 1 mole of PSS, which ensures the conductivity of PEDOT:PSS, thereby reducing the internal resistance of the solid aluminum electrolytic capacitor and ensuring ripple resistance.

[0027] In this invention, a dispersion of a first conductive polymer is first impregnated onto the core package, followed by a dispersion of a second conductive polymer. Thus, the first conductive polymer layer is positioned between the anode foil and the second conductive polymer layer. The weight of sulfonated polyether ether ketone (PEEK) in the first conductive polymer layer accounts for 0.5%-5% of the total weight of the first conductive polymer layer. Because dopant detachment occurs during the charge-discharge cycle of solid aluminum electrolytic capacitors, excessive sulfonated PEEK should be avoided in this invention to prevent corrosion of the anode foil surface caused by the detached PEEK. Therefore, in this invention, sulfonated PEEK is only added to the first conductive polymer layer; the majority of the conductive polymer is still the traditional PEDOT:PSS.

[0028] In this invention, the presence of sulfonated polyether ether ketone (PEEEK) gives it excellent hydrophilicity. Simultaneously, PEEKEK can form chemical bonds with the positively charged portions of PEDOT:PSS, thereby promoting the uniform distribution of PEDOT:PSS in the dispersion and effectively adhering to the anode foil surface. This makes the PEDOT:PSS film less prone to peeling off from the anode foil surface, thus improving the stability of the solid aluminum electrolytic capacitor.

[0029] The presence of sulfonated polyether ether ketone in the first conductive polymer makes the PEDOT:PSS coating easier to spread on the anode foil surface and allows for better penetration into the microscopic irregularities of the substrate surface, thus contributing to a stronger mechanical anchorage. Furthermore, the CS and OSO bonds in the sulfonated polyether ether ketone can form a strong chemical bond with the alumina on the anode foil surface; simultaneously, the benzene rings in the sulfonated polyether ether ketone interact with the benzene rings in PEDOT:PSS through π-π stacking, further enhancing the stability of the PEDOT:PSS film.

[0030] This invention also provides a method for preparing a highly stable solid aluminum electrolytic capacitor, comprising the following steps;

[0031] 1) Prepare sulfonated polyether ether ketone for later use.

[0032] The preparation method of sulfonated polyether ether ketone includes the following steps;

[0033] ① Keep the polyetheretherketone particles at a temperature of 100-200℃ for more than 12 hours, and protect them with nitrogen gas throughout the process;

[0034] ② Add the polyetheretherketone granules obtained in step ① to concentrated sulfuric acid and stir magnetically for more than 12 hours, keeping the temperature between 50-80℃; the weight ratio of polyetheretherketone granules to concentrated sulfuric acid is 1:15-1:25.

[0035] ③ Reduce the temperature of the mixed solution in step ② to 1-5℃, and wash the precipitated sulfonated polyether ether ketone particles with deionized water until the pH of the washing solution reaches 6-7.

[0036] 2) Add the sulfonated polyether ether ketone prepared in step 1) to the PEDOT:PSS dispersion and disperse evenly to form a first conductive polymer dispersion; the weight of the sulfonated polyether ether ketone is 5%-20% of the total weight of the sulfonated polyether ether ketone and PEDOT:PSS. The weight concentration of PEDOT:PSS in the first conductive polymer dispersion is 0.5%-5%.

[0037] 3) Impregnate the core with the first conductive polymer dispersion of PEDOT:PSS from step 2); after drying, form a first conductive polymer layer inside the core; the solvent of the dispersion includes one or more of methanol, ethanol, ethylene glycol, propylene glycol, and DMF. Due to the hydrophilicity of sulfonated polyether ether ketone, the sulfonated polyether ether ketone will slowly dissolve in the solvent of the dispersion during stirring.

[0038] 4) The core package that has completed step 3) is impregnated with the second conductive polymer dispersion, and after drying, a second conductive polymer layer is formed inside the core package; the solute in the second conductive polymer dispersion includes PEDOT:PSS; the weight concentration of PEDOT:PSS in the second conductive polymer dispersion is 0.5%-5%.

[0039] 5) Assemble the core package that has completed step 4).

[0040] In this invention, the core package may be impregnated with a polar solution prior to step 3). The polar solution may be one or more of methanol, ethanol, ethylene glycol, propylene glycol, and DMF. In this invention, impregnating the core package with a certain amount of polar solution beforehand helps to increase the wettability of the anode foil surface. Furthermore, because sulfonated polyether ether ketone has sulfonic acid groups, it possesses hydrophilic properties, meaning it can attract polar molecules and promote wetting and contact between PEDOT:PSS and the anode foil surface. Example 1

[0041] In this embodiment, the weight concentration of PEDOT:PSS in the first conductive polymer dispersion is 4%; the solvent is DMF; and the weight of sulfonated polyether ether ketone accounts for 5% of the total weight of sulfonated polyether ether ketone and PEDOT:PSS. The weight concentration of PEDOT:PSS in the second conductive polymer dispersion is also 4%, and the solvent is also DMF. The core package is impregnated once in the first conductive polymer and four times in the second conductive polymer. Example 2

[0042] In this embodiment, the weight concentration of PEDOT:PSS in the first conductive polymer dispersion is 4%, and the solvent is DMF. Furthermore, the weight of sulfonated polyether ether ketone accounts for 10% of the total weight of sulfonated polyether ether ketone and PEDOT:PSS. Other components are the same as in Example 1. Example 3

[0043] In this embodiment, the weight concentration of PEDOT:PSS in the first conductive polymer dispersion is 4%, and the solvent is DMF; the weight of sulfonated polyether ether ketone accounts for 20% of the total weight of sulfonated polyether ether ketone and PEDOT:PSS. Other parts are the same as in Example 1. Example 4

[0044] In this embodiment, before step 3), i.e. before impregnating the first conductive polymer, a polar solution, DMF, is first impregnated. Everything else is the same as in Example 2.

[0045] Comparative Example 1

[0046] In Comparative Example 1, the first conductive polymer dispersion did not contain sulfonated polyether ether ketone; the other steps were the same as in Example 1.

[0047] Twenty 24V 150μF samples were selected from each of the products in Examples 1, 2, 3, 4, and Comparative Example 1 for surge testing. After 5000 cycles at 80°C, the average capacity retention is shown in the table below: .

Claims

1. A high-stability solid aluminum electrolytic capacitor, characterized in that: The device includes an outer shell, a core package, and a rubber stopper. The core package is sealed inside the outer shell by the rubber stopper. A conductive polymer film is formed inside the core package. The conductive polymer film includes a first conductive polymer layer and a second conductive polymer layer. The first conductive polymer layer is disposed between the anode foil and the second conductive polymer layer. The first conductive polymer layer includes sulfonated polyether ether ketone-doped PEDOT:PSS, and the second conductive polymer layer includes PEDOT:PSS.

2. The high-stability solid aluminum electrolytic capacitor according to claim 1, characterized in that: The first conductive polymer layer is located between the anode foil and the second conductive polymer layer.

3. The high-stability solid aluminum electrolytic capacitor according to claim 1, characterized in that: The weight of sulfonated polyether ether ketone in the first conductive polymer layer accounts for 5%-20% of the total weight of the first conductive polymer layer.

4. The high-stability solid aluminum electrolytic capacitor according to claim 1, characterized in that: Both the first and second conductive polymer layers contain PEDOT:PSS, with a molar ratio of PEDOT to PSS of 4:

1.

5. A method for preparing a high-stability solid aluminum electrolytic capacitor, characterized in that: Includes the following steps; 1) Prepare sulfonated polyether ether ketone for later use; 2) Add the sulfonated polyether ether ketone prepared in step 1) to the PEDOT:PSS dispersion and disperse evenly to form a first conductive polymer dispersion; the weight of the sulfonated polyether ether ketone accounts for 5%-20% of the total weight of the sulfonated polyether ether ketone and PEDOT:PSS. 3) The core package is impregnated with the first conductive polymer dispersion of PEDOT:PSS from step 2); after drying, a first conductive polymer layer is formed inside the core package; 4) The core package that has completed step 3) is impregnated with the second conductive polymer dispersion, and after drying, a second conductive polymer layer is formed inside the core package; the solute in the second conductive polymer dispersion includes PEDOT:PSS; 5) Assemble the core package that has completed step 4).

6. The method for preparing a high-stability solid aluminum electrolytic capacitor according to claim 5, characterized in that: In step 2), the weight concentration of PEDOT:PSS in the first conductive polymer dispersion is 0.5%-5%; the weight of sulfonated polyether ether ketone accounts for 5%-20% of the total weight of sulfonated polyether ether ketone and PEDOT:PSS.

7. The method for preparing a high-stability solid aluminum electrolytic capacitor according to claim 5, characterized in that: In step 4), the weight concentration of PEDOT:PSS in the second conductive polymer dispersion is 0.5%-5%.

8. The method for preparing a high-stability solid aluminum electrolytic capacitor according to claim 5, characterized in that: The core package is impregnated with a polar solution prior to step 3), the polar solution comprising one or more of methanol, ethanol, ethylene glycol, propylene glycol and DMF.

9. The method for preparing a high-stability solid aluminum electrolytic capacitor according to claim 5, characterized in that: The preparation method of the sulfonated polyether ether ketone includes the following steps; ① Keep the polyetheretherketone particles at a temperature of 100-200℃ for more than 12 hours, and protect them with nitrogen gas throughout the process; ② Add the polyetheretherketone granules obtained in step ① to concentrated sulfuric acid and stir magnetically for more than 12 hours, keeping the temperature between 50-80℃; the weight ratio of polyetheretherketone granules to concentrated sulfuric acid is 1:15-1:

25. ③ Reduce the temperature of the mixed solution in step ② to 1-5℃, and wash the precipitated sulfonated polyether ether ketone particles with deionized water until the pH of the washing solution reaches 6-7.