Solid aluminum electrolytic capacitor and preparation method thereof

Abstract

A solid aluminum electrolytic capacitor comprises a core package arranged in a shell in a sealed mode, the core package is formed by winding an anode foil, electrolytic paper and a cathode foil, a conductive high-molecular polymer is formed between the anode foil and the cathode foil, the conductive high-molecular polymer comprises PEDOT: PSS, a copolymer generated through reaction of hydroxyethyl methylacrylate and acrylic acid is inserted in the PEDOT: PSS in a penetrating mode, and the conductive high-molecular polymer is formed by winding of the electrolytic paper and the cathode foil. The weight of the copolymer generated by the reaction of hydroxyethyl methylacrylate and acrylic acid does not exceed 10% of the weight of PEDOT: PSS. According to the invention, the copolymer generated by the reaction of hydroxyethyl methylacrylate and acrylic acid is interspersed on PEDOT: PSS, so that the flexibility and the mechanical property of the conductive high-molecular polymer are improved, and the mechanical property and the cycling stability of the solid aluminum electrolytic capacitor are improved.

Description

Technical Field

[0001] The present invention relates to a solid aluminum electrolytic capacitor and a preparation method thereof, and particularly to a solid aluminum electrolytic capacitor with good mechanical properties and cyclic stability performance. Background Art

[0002] In solid aluminum electrolytic capacitors, commonly used conductive polymer materials include polypyrrole, polyaniline, and PEDOT:PSS. Due to their comprehensive advantages in terms of conductivity, stability, film thickness uniformity, corrosion resistance, and production processes, most capacitor manufacturers currently use PEDOT:PSS as the solid electrolyte for solid aluminum electrolytic capacitors. Since the material of the solid electrolyte in solid aluminum electrolytic capacitors is very brittle, it makes the solid capacitors extremely prone to "spark" phenomena due to mechanical movements such as dropping and collision.

[0003] At the same time, since PEDOT:PSS as the solid electrolyte of solid aluminum electrolytic capacitors is very brittle, during the charge and discharge cycles of solid aluminum electrolytic capacitors, PEDOT:PSS continuously expands and contracts, and the PEDOT:PSS on the surface of the anode foil of solid aluminum electrolytic capacitors is prone to peeling, resulting in a decrease in capacitance, thus affecting the stability of the electrical performance of the product. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a solid aluminum electrolytic capacitor with good mechanical properties and cyclic stability performance and a preparation method thereof.

[0005] To solve the above technical problem, the technical solution proposed by the present invention is: a solid aluminum electrolytic capacitor, including a core package hermetically arranged in a housing, the core package is wound by an anode foil, electrolytic paper, and a cathode foil, a conductive polymer is formed between the anode foil and the cathode foil, the conductive polymer includes PEDOT:PSS, and a copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid is interspersed in the PEDOT:PSS, and the weight of the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid does not exceed 10% of the weight of PEDOT:PSS.

[0006] For the above solid aluminum electrolytic capacitor, preferably, the weight of the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid is 2%-5% of the weight of PEDOT:PSS.

[0007] For the above solid aluminum electrolytic capacitor, preferably, N,N'-methylenebisacrylamide is cross-linked on the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid; the weight of the N,N'-methylenebisacrylamide does not exceed 5% of the weight of the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid.

[0008] A preparation method of a solid aluminum electrolytic capacitor, comprising the following steps; 1) Disperse PEDOT:PSS evenly in an aqueous solution or an organic solvent to form a dispersion liquid, and the weight concentration of PEDOT:PSS does not exceed 5%; 2) Add hydroxyethyl methacrylate and acrylic acid respectively to the dispersion liquid in step 1), stir evenly to form an impregnating liquid; the total weight of hydroxyethyl methacrylate and acrylic acid does not exceed 10% of the weight of PEDOT:PSS; 3) Impregnate the core with the impregnating liquid in step 2), adopt vacuum impregnation or pressure impregnation, and heat and dry; 4) Complete the impregnation of the core in step 3) with an ammonium persulfate solution; 5) Heat, and a copolymerization reaction of hydroxyethyl methacrylate and acrylic acid occurs in the core package; so that a copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid is interspersed on the PEDOT:PSS.

[0009] In the above preparation method of the solid aluminum electrolytic capacitor, preferably, add the ammonium persulfate in step 4) to the dispersion liquid in step 2).

[0010] 6) According to the preparation method of the solid aluminum electrolytic capacitor described in claim 4, it is characterized in that: N,N'-methylenebisacrylamide is added to the dispersion liquid in step 2); the weight of N,N'-methylenebisacrylamide does not exceed 5% of the weight of the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid.

[0011] In the above preparation method of the solid aluminum electrolytic capacitor, preferably, the weight of the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid in step 2) is 2%-5% of the weight of PEDOT:PSS.

[0012] Compared with the prior art, the advantages of the present invention are as follows: in the present invention, by interspersing a copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid on the PEDOT:PSS, the flexibility and mechanical properties of the conductive polymer are improved, thereby improving the mechanical properties and cycle stability of the solid aluminum electrolytic capacitor. Specific embodiments

[0013] For the convenience of understanding the present invention, the following will describe the present invention more comprehensively and meticulously in combination with preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0014] It should be specifically noted that when a certain component is described as "fixed to, fixedly connected to, connected to, or communicated with" another component, it can be directly fixed, fixedly connected, connected, or communicated with the other component, or it can be indirectly fixed, fixedly connected, connected, or communicated with the other component through other intermediate connecting members.

[0015] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly 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 protection scope of the present invention. Embodiment 1

[0016] A solid aluminum electrolytic capacitor includes a core package sealed in a housing. The core package is wound by an anode foil, electrolytic paper, and a cathode foil. A conductive polymer is formed between the anode foil and the cathode foil. The conductive polymer includes PEDOT:PSS, and a copolymer formed by the reaction of 2-hydroxyethyl methacrylate and acrylic acid is interspersed in the PEDOT:PSS. The weight of the copolymer formed by the reaction of 2-hydroxyethyl methacrylate and acrylic acid does not exceed 10% of the weight of PEDOT:PSS, preferably between 2% and 5%. In this embodiment, the content of the copolymer formed by the reaction of 2-hydroxyethyl methacrylate and acrylic acid cannot be too high, otherwise it may reduce the conductivity of the conductive polymer.

[0017] In this embodiment, since the copolymer formed by the reaction of 2-hydroxyethyl methacrylate and acrylic acid is interspersed in the PEDOT:PSS, during the charge and discharge cycle of the solid aluminum electrolytic capacitor, the toughness of the expansion and contraction of the PEDOT:PSS is improved, so that the PEDOT:PSS is not so easy to form peeling on the surface of the anode foil; thereby improving the cycle stability of the solid aluminum electrolytic capacitor. At the same time, in this application, the copolymer formed by the reaction of 2-hydroxyethyl methacrylate and acrylic acid interspersed in the PEDOT:PSS can improve the flexibility of the conductive polymer, thereby improving the mechanical properties of the solid aluminum electrolytic capacitor.

[0018] In this embodiment, in order to improve the cross-linking effect of the copolymer formed by the reaction of 2-hydroxyethyl methacrylate and acrylic acid, N,N'-methylenebisacrylamide is cross-linked on the copolymer formed by the reaction of 2-hydroxyethyl methacrylate and acrylic acid. The weight of N,N'-methylenebisacrylamide does not exceed 5% of the weight of the copolymer formed by the reaction of 2-hydroxyethyl methacrylate and acrylic acid.

[0019] This embodiment also provides a preparation method of a solid aluminum electrolytic capacitor, including the following steps; 1) Disperse PEDOT:PSS evenly in an aqueous solution or an organic solvent to form a dispersion, and the weight concentration of PEDOT:PSS does not exceed 5%. In this embodiment, the solvent of the dispersion is deionized water, and organic solvents such as alcohols can also be used, such as ethanol, ethylene glycol, propylene glycol, glycerol, etc.

[0020] 2) Add hydroxyethyl methacrylate and acrylic acid to the dispersion in step 1) respectively, stir evenly to form an impregnating solution; the total weight of hydroxyethyl methacrylate and acrylic acid does not exceed 10% of the weight of PEDOT:PSS, preferably between 2% - 5%; N,N'-methylenebisacrylamide is added to the dispersion in step 2); the weight of N,N'-methylenebisacrylamide does not exceed 5% of the weight of the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid.

[0021] 3) Immerse the core in the impregnating solution in step 2), use vacuum impregnation or pressure impregnation, and heat and dry it to facilitate the impregnation of the ammonium persulfate solution.

[0022] 4) Complete the impregnation of the core in step 3) with the ammonium persulfate solution.

[0023] 5) Heat, and a copolymerization reaction of hydroxyethyl methacrylate and acrylic acid occurs in the core; so that the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid is interspersed on PEDOT:PSS; the heating temperature is between 40 - 80 °C.

[0024] In this embodiment, the ammonium persulfate in step 4) can be added to the dispersion in step 2), and step 4) can be cancelled. In this embodiment, ammonium persulfate is added as an initiator to the reaction, under the condition of heating; ammonium persulfate decomposes to generate sulfate radicals (SO4• - )), and the generated radicals attack the double bonds (C=C) in the hydroxyethyl methacrylate and acrylic acid monomers to form monomer radicals; these monomer radicals continue to react with other monomer molecules to form polymer chains. The hydroxyethyl methacrylate and acrylic acid monomers combine alternately or randomly through free radical polymerization to form copolymer chains. N,N'-methylenebisacrylamide is added as a crosslinking agent to the reaction, and the double bonds of N,N'-methylenebisacrylamide will also participate in the free radical polymerization reaction. N,N'-methylenebisacrylamide connects different polymer chains to form a stable three-dimensional network structure. In this embodiment, PEDOT:PSS does not participate in the copolymerization reaction of hydroxyethyl methacrylate and acrylic acid; however, after the copolymerization reaction of hydroxyethyl methacrylate and acrylic acid, the copolymer of hydroxyethyl methacrylate and acrylic acid forms an interspersed structure on PEDOT:PSS, improving the cycle stability of the conductive polymer; at the same time, under the action of the copolymer of hydroxyethyl methacrylate and acrylic acid, the flexibility and mechanical strength of the conductive polymer are also improved.

[0025] Example 2 In this example, crosslinking agent N,N'-methylenebisacrylamide was not added to the copolymerization reaction of hydroxyethyl methacrylate and acrylic acid, and the others were the same as in Example 1; due to the absence of the crosslinking agent, the copolymer of hydroxyethyl methacrylate and acrylic acid did not form a stable three-dimensional network structure, resulting in the cyclic stability of the solid aluminum electrolytic capacitor being inferior to that of the solid aluminum electrolytic capacitor in Example 1.

[0026] Comparative Example 1 In Comparative Example 1, the conductive polymer on the core package was only PEDOT:PSS; the others were the same as in Example 1.

[0027] Prepare 30 solid aluminum electrolytic capacitors of 24V and 400μF in Example 1, Example 2 and Comparative Example 1. Take 10 of them for vibration test, drop test and charge-discharge cycle test respectively, and record their drop test and vibration test and leakage current change. The results are shown in Table 1 and Table 2; Table 1 is the average leakage current table of the products in Example 1, Example 2 and Comparative Example 1 before and after the drop test, and Table 2 is the average leakage current table of the products in Example 1, Example 2 and Comparative Example 1 before and after the vibration test; the vibration test was carried out according to the IEC60068-2-6 standard. Table 3 is the capacitance retention rate of the capacitor after 10,000 charge-discharge cycles.

[0028] Table 1 is the average leakage current table of the products in Example 1, Example 2 and Comparative Example 1 before and after the drop test.

[0029]

[0031] The drop test in this example was to place the product 1 meter above the ground and then free-fall it onto a hard ground 30 times.

[0032] Table 2 is the leakage current table of the products in Example 1, Example 2 and Comparative Example 1 before and after the vibration test.

[0033]

[0034] Table 3 is the initial capacitance of the products in Example 1, Example 2 and Comparative Example 1, and the average value of the capacitance retention rate after 10,000 charge-discharge cycles; the results are as follows:

Claims

1. A solid aluminum electrolytic capacitor, characterized in that: It includes a core package hermetically arranged inside a housing, and the core package is wound by an anode foil, an electrolytic paper and a cathode foil. A conductive polymer is formed between the anode foil and the cathode foil. The conductive polymer includes PEDOT:PSS, and a copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid is interspersed in the PEDOT:PSS. The weight of the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid does not exceed 10% of the weight of PEDOT:PSS.

2. The solid aluminum electrolytic capacitor according to claim 1, wherein: The weight of the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid is 2%-5% of the weight of PEDOT:PSS.

3. The solid aluminum electrolytic capacitor according to claim 1, characterized in that: N,N'-methylenebisacrylamide is cross-linked on the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid; the weight of the N,N'-methylenebisacrylamide does not exceed 5% of the weight of the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid.

4. A method for preparing a solid aluminum electrolytic capacitor, characterized in that: It includes the following steps; 1) Disperse PEDOT:PSS evenly in an aqueous solution or an organic solvent to form a dispersion liquid, and the weight concentration of PEDOT:PSS does not exceed 5%; 2) Add hydroxyethyl methacrylate and acrylic acid respectively to the dispersion liquid in step 1), stir evenly to form an impregnating liquid; the total weight of hydroxyethyl methacrylate and acrylic acid does not exceed 10% of the weight of PEDOT:PSS; 3) Impregnate the core package with the impregnating liquid in step 2), adopt vacuum impregnation or pressure impregnation, and heat and dry; 4) Immerse the core package completed in step 3) in an ammonium persulfate solution; 5) Heat to carry out the copolymerization reaction of hydroxyethyl methacrylate and acrylic acid inside the core package; so that the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid is interspersed in the PEDOT:PSS.

5. The manufacturing method of the solid aluminum electrolytic capacitor according to claim 4, characterized in that: Add the ammonium persulfate in step 4) to the dispersion liquid in step 2).

6. The preparation method of the solid aluminum electrolytic capacitor according to claim 4, wherein: N,N'-methylenebisacrylamide is added to the dispersion liquid in step 2); the weight of the N,N'-methylenebisacrylamide does not exceed 5% of the weight of the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid.

7. The preparation method of the solid aluminum electrolytic capacitor according to claim 4, characterized in that: The weight of the copolymer formed by the reaction of hydroxyethyl methacrylate and acrylic acid in step 2) is 2%-5% of the weight of PEDOT:PSS.

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