High-stability solid aluminum electrolytic capacitor and preparation method thereof

Abstract

A high-stability solid aluminum electrolytic capacitor comprises a shell, a core package and a rubber plug, the core package is arranged in the shell in a sealed mode through the rubber plug, a conductive high-molecular polymer film is formed in the core package, and the conductive high-molecular polymer film comprises a first conductive high-molecular polymer layer and a second conductive high-molecular polymer layer; the first conductive high-molecular polymer layer comprises PEDOT: PSS doped with sulfonated polyetheretherketone, and the second conductive high-molecular polymer layer comprises PEDOT: PSS. According to the invention, the adhesion between the PEDOT: PSS and the anode foil can be improved by introducing the polyether-ether-ketone, so that the cycle stability of the solid aluminum electrolytic capacitor is improved.

Description

Technical Field

[0001] The invention relates to an aluminum electrolytic capacitor, and in particular to a high-stability solid aluminum electrolytic capacitor and a preparation method thereof. Background Art

[0002] At present, solid aluminum electrolytic capacitors do not contain electrolyte, so there is no risk of leakage and fire when the capacitor valve is opened, which makes solid aluminum electrolytic capacitors have important advantages in widespread use. The electrolyte of solid aluminum electrolytic capacitors usually uses PEDOT or PEDOT:PSS. During the charge and discharge cycle of aluminum electrolytic capacitors, PEDOT or PEDOT:PSS will continue to expand and contract, causing the conductive polymer to peel off from the surface of the anode foil, which in turn causes a sharp drop in capacity. At the same time, there are water molecules in the conductive polymer, which are electrolyzed to produce oxygen molecules, which accelerate the oxidation and peeling of the conductive polymer on the surface of the anode foil. Summary of the invention

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

[0004] In order to solve the above technical problems, the technical solutions proposed in the present invention are as follows: 1. A high-stability solid aluminum electrolytic capacitor, comprising a shell, a core package and a rubber plug, wherein the core package is sealed in the shell by the rubber plug, and a conductive polymer film is formed in the core package, wherein the conductive polymer film comprises a first conductive polymer layer and a second conductive polymer layer; the first conductive polymer layer comprises PEDOT:PSS doped with sulfonated polyetheretherketone, and the second conductive polymer layer comprises PEDOT:PSS.

[0005] In the above-mentioned high-stability solid aluminum electrolytic capacitor, preferably, the first conductive high polymer layer is located between the anode foil and the second conductive high polymer layer.

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

[0007] In the above-mentioned high-stability solid aluminum electrolytic capacitor, preferably, 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 comprises the following steps: 1) preparing sulfonated polyetheretherketone for standby use; 2) adding the sulfonated polyetheretherketone prepared in step 1) into the dispersion of PEDOT:PSS and dispersing the dispersion evenly to form a first conductive polymer dispersion; the weight of the sulfonated polyetheretherketone is 5%-20% of the total weight of the sulfonated polyetheretherketone and PEDOT:PSS; 3) The core package is immersed in the first conductive polymer dispersion of PEDOT:PSS in step 2); after drying, a first conductive polymer layer is formed in the core package; 4) The core package obtained in step 3) is immersed in a second conductive polymer dispersion, and after drying, a first conductive polymer layer is formed in the core package; the solute in the second conductive polymer dispersion includes PEDOT:PSS; 5) Assemble the core package completed in step 4).

[0009] 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%; the weight of sulfonated polyetheretherketone accounts for 5%-20% of the total weight of sulfonated polyetheretherketone and PEDOT:PSS.

[0010] In the above method for preparing a high-stability solid aluminum electrolytic capacitor, preferably, in step 4), the weight concentration of PEDOT:PSS in the second conductive polymer dispersion is 0.5%-5%.

[0011] In the above method for preparing a high-stability solid aluminum electrolytic capacitor, preferably, the core package is impregnated with a polar solution before step 3), and the polar solution includes one or more of methanol, ethanol, ethylene glycol, propylene glycol and DMF.

[0012] The method for preparing the above-mentioned high-stability solid aluminum electrolytic capacitor, preferably, the method for preparing the sulfonated polyetheretherketone comprises the following steps; ① Keep the polyetheretherketone particles at a temperature of 100-200℃ for more than 12 hours, and use nitrogen protection throughout the process; ② Add the polyetheretherketone particles obtained in step ① into concentrated sulfuric acid, stir magnetically for more than 12 hours, and keep the temperature between 50-80° C.; the weight ratio of the polyetheretherketone particles to the concentrated sulfuric acid is 1:15-1:25; ③ Lower the temperature of the mixed solution in step ② to 1-5° C., and wash the precipitated sulfonated polyetheretherketone particles with deionized water until the pH value of the washing solution reaches 6-7.

[0013] 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 DESCRIPTION

[0014] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0015] It should be noted that when an element is described as being "fixed, fixed, connected or connected to" another element, it can be directly fixed, fixed, connected or connected to the other element, or it can be indirectly fixed, fixed, connected or connected to the other element through other intermediate connectors.

[0016] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0017] A high-stability solid aluminum electrolytic capacitor includes a shell, a core bag and a rubber plug, wherein the core bag is sealed in the shell by the rubber plug, a conductive polymer film is formed in the core bag, and the conductive polymer film includes a first conductive polymer layer and a second conductive polymer layer; the first conductive polymer layer includes PEDOT:PSS doped with sulfonated polyetheretherketone, and the second conductive polymer layer includes PEDOT:PSS. In the present invention, the addition of sulfonated polyetheretherketone on the first conductive polymer layer can enhance the adhesion between PEDOT:PSS and anode foil, thereby improving the cycle stability of the solid aluminum electrolytic capacitor.

[0018] In the present invention, the molar ratio of PEDOT:PSS in the first conductive polymer layer and the second conductive polymer layer is 4:1; in PEDOT:PSS, 1 mole of PSS is doped with every 4 moles of PEDOT, so that the conductivity of PEDOT:PSS can be guaranteed, thereby reducing the internal resistance of the solid aluminum electrolytic capacitor, thereby ensuring the ripple resistance performance.

[0019] In the present invention, the core package is first impregnated with a dispersion of a first conductive polymer, and then with a dispersion of a second conductive polymer; in this way, the first conductive polymer layer is placed between the anode foil and the second conductive polymer layer. The weight of the sulfonated polyetheretherketone in the first conductive polymer layer accounts for 0.5%-5% of the total weight of the first conductive polymer layer. Due to the phenomenon of dopant detachment during the charge and discharge cycle of the solid aluminum electrolytic capacitor, the present invention should avoid adding too much sulfonated polyetheretherketone to prevent the sulfonated polyetheretherketone generated by the detachment phenomenon from corroding the surface of the anode foil. Therefore, in the present invention, only the first conductive polymer layer is added with sulfonated polyetheretherketone; more polymer conductive polymers still use traditional PEDOT:PSS.

[0020] In the present invention, due to the presence of sulfonic acid groups, sulfonated polyetheretherketone has good hydrophilicity. At the same time, sulfonated polyetheretherketone can form chemical bonds with the positively charged part of PEDOT:PSS, thereby promoting the uniform distribution of PEDOT:PSS in the dispersion and effectively attaching it to the surface of the anode foil. In this way, the PEDOT:PSS film is not easy to peel off from the surface of the anode foil, thereby improving the stability of the solid aluminum electrolytic capacitor.

[0021] Due to the presence of sulfonated polyetheretherketone in the first conductive polymer, the PEDOT:PSS coating is easier to spread on the surface of the anode foil and can better penetrate into the microscopic uneven structure of the substrate surface, thus helping to form a stronger mechanical anchor. In addition, the CS and OSO bonds in the sulfonated polyetheretherketone can form a strong chemical bond with the aluminum oxide on the surface of the anode foil; at the same time, the benzene rings in the sulfonated polyetheretherketone interact with the benzene rings in PEDOT:PSS through π-π stacking, further enhancing the stability of the PEDOT:PSS film.

[0022] The present invention also provides a method for preparing a high-stability solid aluminum electrolytic capacitor, comprising the following steps: 1) Prepare sulfonated polyetheretherketone for later use.

[0023] The preparation method of sulfonated polyetheretherketone comprises the following steps: ① Keep the polyetheretherketone particles at a temperature of 100-200℃ for more than 12 hours, and use nitrogen protection throughout the process; ② Add the polyetheretherketone particles obtained in step ① into concentrated sulfuric acid, stir magnetically for more than 12 hours, and keep the temperature between 50-80° C.; the weight ratio of the polyetheretherketone particles to the concentrated sulfuric acid is 1:15-1:25; ③ Lower the temperature of the mixed solution in step ② to 1-5° C., and wash the precipitated sulfonated polyetheretherketone particles with deionized water until the pH value of the washing solution reaches 6-7.

[0024] 2) Add the sulfonated polyetheretherketone prepared in step 1) to the dispersion of PEDOT:PSS and disperse evenly to form a first conductive polymer dispersion; the weight of the sulfonated polyetheretherketone is 5%-20% of the total weight of the sulfonated polyetheretherketone and PEDOT:PSS. The weight concentration of PEDOT:PSS in the first conductive polymer dispersion is 0.5%-5%.

[0025] 3) The core package is immersed in the first conductive polymer dispersion of PEDOT:PSS in step 2); after drying, a first conductive polymer layer is formed in the core package; the solvent of the dispersion includes one or more of methanol, ethanol, ethylene glycol, propylene glycol and DMF. Due to the hydrophilicity of sulfonated polyetheretherketone, sulfonated polyetheretherketone will slowly dissolve in the solvent of the dispersion during stirring.

[0026] 4) The core package obtained in step 3) is immersed in a second conductive polymer dispersion, and after drying, a first conductive polymer layer is formed in 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%.

[0027] 5) Assemble the core package completed in step 4).

[0028] In the present invention, the core package may be impregnated with a polar solution before step 3), and the polar solution may be one or more of methanol, ethanol, ethylene glycol, propylene glycol and DMF. In the present invention, by first impregnating the core package with a certain amount of polar solution, the wettability of the anode foil surface is improved; and since sulfonated polyetheretherketone has a sulfonic acid group, it has hydrophilic properties, which means that it can attract polar molecules and promote the wetting and contact between PEDOT:PSS and the anode foil surface. Example 1

[0029] 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 polyetheretherketone accounts for 5% of the total weight of sulfonated polyetheretherketone 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

[0030] In this embodiment, the weight concentration of PEDOT:PSS in the first conductive polymer dispersion is 4%, and the solvent is DMF. In addition, the weight of sulfonated polyetheretherketone accounts for 10% of the total weight of sulfonated polyetheretherketone and PEDOT:PSS. Other parts are the same as in Example 1. Example 3

[0031] 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 polyetheretherketone accounts for 20% of the total weight of sulfonated polyetheretherketone and PEDOT:PSS. Other parts are the same as in embodiment 1. Example 4

[0032] In this embodiment, before step 3), that is, before impregnating the first conductive polymer, a polar solution is first impregnated, and the polar solution is DMF. Other steps are the same as those in embodiment 2.

[0033] Comparative Example 1 In Comparative Example 1, no sulfonated polyetheretherketone was added to the first conductive polymer dispersion; the other steps were the same as those in Example 1.

[0034] 20 24V 150μF samples were selected from the products of Example 1, Example 2, Example 3, Example 4 and Comparative Example 1 for surge testing. After 5000 cycles at 80°C, the average capacity retention rate is shown in the following table: Capacity retention after 5000 cycles Example 1 90.3% Example 2 91.7% Example 3 90.8% Example 4 92.1% Comparative Example 1 85.6%

Claims

1. A high-stability solid aluminum electrolytic capacitor, characterized in that: It includes an outer shell, a core package and a rubber plug. The core package is sealed in the outer shell by the rubber plug. A conductive polymer film is formed in the core package. The conductive polymer film includes a first conductive polymer layer and a second conductive polymer layer. The first conductive polymer layer includes PEDOT:PSS doped with sulfonated polyetheretherketone, 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 high polymer layer is located between the anode foil and the second conductive high polymer layer.

3. The high-stability solid aluminum electrolytic capacitor according to claim 1, characterized in that: The weight of the sulfonated polyetheretherketone 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: The molar ratio of PEDOT:PSS in the first conductive polymer layer and the second conductive polymer layer is 4:

1.

5. A method for preparing a high-stability solid aluminum electrolytic capacitor, characterized in that: The steps include: 1) preparing sulfonated polyetheretherketone for standby use; 2) adding the sulfonated polyetheretherketone prepared in step 1) to the dispersion of PEDOT:PSS and dispersing the dispersion evenly to form a first conductive polymer dispersion; the weight of the sulfonated polyetheretherketone accounts for 5%-20% of the total weight of the sulfonated polyetheretherketone and PEDOT:PSS; 3) The core package is immersed in the first conductive polymer dispersion of PEDOT:PSS in step 2); after drying, a first conductive polymer layer is formed in the core package; 4) The core package obtained in step 3) is immersed in a second conductive polymer dispersion, and after drying, a first conductive polymer layer is formed in the core package; the solute in the second conductive polymer dispersion includes PEDOT:PSS; 5) Assemble the core package completed in step 4).

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

7. The method for preparing a high-stability solid aluminum electrolytic capacitor according to claim 5, characterized in that: In the 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 before step 3), wherein the polar solution includes 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 polyetheretherketone comprises the following steps: ① Keep the polyetheretherketone particles at a temperature of 100-200℃ for more than 12 hours, and use nitrogen protection throughout the process; ② Add the polyetheretherketone particles obtained in step ① into concentrated sulfuric acid, stir magnetically for more than 12 hours, and keep the temperature between 50-80° C.; the weight ratio of the polyetheretherketone particles to the concentrated sulfuric acid is 1:15-1:25; ③ Lower the temperature of the mixed solution in step ② to 1-5° C., and wash the precipitated sulfonated polyetheretherketone particles with deionized water until the pH value of the washing solution reaches 6-7.