Solid aluminum electrolytic capacitor with good stability and preparation method thereof

Abstract

The application discloses a solid aluminum electrolytic capacitor with good stability, which comprises a core package and a shell, and the core package is sealed in the shell through a sealing element; a conductive polymer is formed in the core package, and the conductive polymer comprises PEDOT:PSS grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups. In the application, the phosphite antioxidant functional groups can decompose hydrogen peroxide, convert unstable hydrogen peroxide into stable alcohol, and thus prevent the generation of free oxygen; the hindered phenolic antioxidant functional groups can effectively capture free oxygen, thus blocking the attack of free oxygen on PEDOT:PSS, and ensuring the stability of PEDOT:PSS in the core package.

Description

Technical Field

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

[0002] Solid-state aluminum electrolytic capacitors use conductive polymer PEDOT:PSS instead of traditional electrolytes, offering advantages such as low ESR, high reliability, and long lifespan. They are widely used in fast charging, AI server power supplies, and automotive electronics. Especially in AI server power supplies, the requirements for the internal resistance and cycle life of solid-state aluminum electrolytic capacitors are extremely high.

[0003] During the production process of solid aluminum electrolytic capacitors, the core inevitably comes into contact with air, thus absorbing moisture from the air. Under the influence of the unavoidable leakage current in solid aluminum electrolytic capacitors, the absorbed moisture is electrolyzed to produce free oxygen. This free oxygen attacks PEDOT:PSS, causing a sharp drop in conductivity and a surge in ESR. The PEDOT:PSS film peels off from the anode foil, thus shortening the lifespan. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a solid aluminum electrolytic capacitor grafted with antioxidant functional groups on PEDOT:PSS and its preparation method.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by the present invention is as follows: a solid aluminum electrolytic capacitor with good stability, comprising a core and a shell, wherein the core is sealed inside the shell by a sealing element; a conductive polymer is formed inside the core, wherein the conductive polymer comprises PEDOT:PSS grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups.

[0006] Preferably, in the above-mentioned stable solid aluminum electrolytic capacitor, the amount of hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups grafted onto PEDOT:PSS is 0.5%-10% of the weight of PEDOT:PSS.

[0007] Preferably, in the above-mentioned stable solid aluminum electrolytic capacitor, the hindered phenolic antioxidant functional group includes one or more of 3,5-di-tert-butyl-4-hydroxybenzoic acid, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 3,5-di-tert-butyl-4-hydroxyphenyl acrylate, 3,5-di-tert-butyl-4-hydroxystyrene, and 3-tert-butyl-5-methyl-4-hydroxyphenylpropionic acid.

[0008] Preferably, in the above-mentioned stable solid aluminum electrolytic capacitor, the phosphite antioxidant functional group includes one or more of monocarboxyphenyl phosphite, dicarboxyphosphite, hydroxyalkylaryl phosphite, and polyol-type phosphite.

[0009] A method for preparing a stable solid aluminum electrolytic capacitor includes the following steps:

[0010] 1) PEDOT: PSS grafts hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups;

[0011] 2) Disperse the EDOT monomer grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups obtained in step 1 into deionized water, then add PSS, and add ammonium persulfate dropwise. Polymerize at 0-10℃ for 12-36 hours to obtain PEDOT:PSS grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups; the molar ratio of EDOT to PSS is 1:2-1:5; the molar ratio of ammonium persulfate to EDOT is 1:1-2:1.

[0012] 3) The core contains the PEDOT:PSS dispersion grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups from step 2).

[0013] 4) Assemble to form a solid aluminum electrolytic capacitor.

[0014] The preferred method for preparing the above-mentioned stable solid aluminum electrolytic capacitor includes step 1) comprising the following steps:

[0015] 1.1) Mix EDOT monomers and hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups evenly according to a preset ratio;

[0016] 1.2) Add a catalyst to the mixed solution in step 1.1) and react under nitrogen protection for 12-24 hours at a reaction temperature of 50-80℃; the catalyst includes N,N'-dicyclohexylcarbodiimide and / or p-dimethylaminopyridine;

[0017] 1.3) The reactants obtained in step 1.2) are filtered and subjected to column chromatography to obtain EDOT monomers grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups.

[0018] A method for preparing a stable solid aluminum electrolytic capacitor includes the following steps:

[0019] 1) Add PEDOT:PSS to deionized water and disperse evenly; add epoxy crosslinking agent (glyceryl glycidyl ether or polyethylene glycol diglycidyl ether).

[0020] 2) The core contains the PEDOT:PSS dispersion impregnated in step 1);

[0021] 3) Dry the core package from step 2) at a temperature of 80-140℃;

[0022] 4) The core from step 3) comprises a condensation system containing hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups; dried;

[0023] 5) Assemble to form a solid aluminum electrolytic capacitor.

[0024] In the above-mentioned method for preparing a stable solid aluminum electrolytic capacitor, preferably, the epoxy crosslinking agent includes glycerol glycidyl ether and / or polyethylene glycol diglycidyl ether.

[0025] Compared with the prior art, the advantages of the present invention are as follows: In the present invention, the phosphite antioxidant functional groups can decompose hydroperoxides and convert unstable hydroperoxides into stable alcohols, thereby preventing the generation of free oxygen; the hindered phenolic antioxidant functional groups can effectively capture free oxygen, thereby blocking the attack of free oxygen on PEDOT:PSS and ensuring the stability of PEDOT:PSS in the core package. Detailed Implementation

[0026] 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.

[0027] 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.

[0028] 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.

[0029] Example 1

[0030] A stable solid aluminum electrolytic capacitor includes a core and a shell. The core is sealed inside the shell by a sealing element. A conductive polymer is formed inside the core. The conductive polymer includes PEDOT:PSS grafted with hindered phenolic antioxidant functional groups and phosphite antioxidant functional groups.

[0031] In this embodiment, the amount of hindered phenolic antioxidant functional groups and phosphite antioxidant functional groups grafted onto PEDOT:PSS is 0.5%-10% of the weight of PEDOT:PSS.

[0032] In this embodiment, the compound with the hindered phenolic antioxidant functional group is 3,5-di-tert-butyl-4-hydroxybenzoic acid. In other embodiments, one or more of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 3,5-di-tert-butyl-4-hydroxyphenyl acrylate, 3,5-di-tert-butyl-4-hydroxystyrene, and 3-tert-butyl-5-methyl-4-hydroxyphenylpropionic acid may also be used.

[0033] In this embodiment, the compound with the antioxidant functional group of phosphite is a monocarboxyphenyl phosphite. In other embodiments, one or more of the following can also be used: dicarboxyphosphite, hydroxyalkylaryl phosphite, and polyol-type phosphite.

[0034] In the production process of the solid aluminum electrolytic capacitor of this invention, the core is inevitably exposed to air and absorbs moisture from the air; under the action of leakage current, this moisture is electrolyzed to generate free oxygen. In this invention, phosphite antioxidant functional groups can decompose hydroperoxides, converting unstable hydroperoxides into stable alcohols, thereby preventing the generation of free oxygen; hindered phenolic antioxidant functional groups can effectively capture free oxygen, thereby blocking the attack of free oxygen on PEDOT:PSS and ensuring the stability of PEDOT:PSS within the core.

[0035] In this embodiment, hindered phenolic antioxidant functional groups and phosphite antioxidant functional groups can be grafted onto PEDOT or PSS, but the methods of grafting onto PEDOT and PSS are different.

[0036] In this embodiment, the method of grafting onto PEDOT includes the following steps:

[0037] 1) PEDOT: PSS grafts hindered phenolic antioxidant functional groups and phosphite antioxidant functional groups.

[0038] 1.1) Mix the EDOT monomer, hindered phenolic antioxidant functional groups, and phosphite antioxidant functional groups evenly according to a preset ratio;

[0039] 1.2) Add the catalyst to the mixed solution in step 1.1) and react under nitrogen protection for 12-24 hours at a reaction temperature of 50-80°C; the catalyst includes N,N'-dicyclohexylcarbodiimide (DCC) and p-dimethylaminopyridine (DMAP); in this embodiment, the solvent for the catalyst can be anhydrous dichloromethane;

[0040] 1.3) The reactants obtained in step 1.2) are filtered and subjected to column chromatography to obtain EDOT monomers grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups.

[0041] In this embodiment, EDOT is used as the grafting matrix; hindered phenolic antioxidant functional groups and phosphite antioxidant functional groups are employed, and covalent grafting is achieved in anhydrous dichloromethane via a DCC-DMAP system through esterification. DCC activates the carboxyl group of the antioxidant molecule to form an acyl active intermediate, and DMAP catalyzes the esterification of the intermediate with the primary hydroxyl group of the EDOT side chain to form a stable ester bond. The byproduct dicyclohexylurea can be removed by filtration. The reaction utilizes only the carboxyl group for bonding, and the active phenolic hydroxyl group of the hindered phenol and the trivalent phosphorus antioxidant core structure of the phosphite are both preserved. The resulting functionalized EDOT monomer can be oxidatively polymerized with ammonium persulfate to generate PEDOT with covalently bonded side chains of the two types of antioxidant functional groups, thereby polymerizing to generate PEDOT:PSS.

[0042] 2) Disperse the EDOT monomer grafted with hindered phenolic antioxidant functional groups and phosphite antioxidant functional groups obtained in step 1 into deionized water, then add PSS, add ammonium persulfate dropwise, and polymerize at 0-10℃ for 12-36 hours to obtain PEDOT:PSS grafted with hindered phenolic antioxidant functional groups and phosphite antioxidant functional groups; the molar ratio of EDOT to PSS is 1:2-1:5; the molar ratio of ammonium persulfate to EDOT is 1:1-2:1.

[0043] 3) The core contains a PEDOT:PSS dispersion grafted with hindered phenolic antioxidant functional groups and phosphite antioxidant functional groups from step 2). Inside the core, the hindered phenols capture oxidative free radicals to terminate the chain reaction, and the phosphites decompose hydrogen peroxide to inhibit the generation of new free radicals. The two work together to exert a long-lasting antioxidant effect, and the antioxidant groups are fixed by chemical bonds without migration or precipitation problems.

[0044] 4) Assemble to form a solid aluminum electrolytic capacitor.

[0045] In this embodiment, the method of grafting onto the PSS includes the following steps:

[0046] a) Add PEDOT:PSS to deionized water and disperse evenly; add epoxy crosslinking agent, which can be glyceryl glycidyl ether or / and polyethylene glycol diglycidyl ether;

[0047] b) The core contains the PEDOT:PSS dispersion impregnated in step 1);

[0048] c) Dry the core package from step 2) at a temperature of 80-140°C;

[0049] d) The core from step 3) comprises a condensation system containing hindered phenolic antioxidant functional groups and phosphite antioxidant functional groups; dried;

[0050] e) Assemble to form a solid aluminum electrolytic capacitor.

[0051] In this embodiment, PEDOT:PSS is dispersed in deionized water and a water-soluble epoxy crosslinking agent is added. The sulfonic acid in the PSS side chain catalyzes the protonation and ring-opening of the epoxy three-membered ring. One end of the epoxy is covalently anchored to the PSS molecular chain through SOC bonds, while the other end generates a large number of secondary hydroxyl groups as active grafting sites. This epoxy bridge chain can crosslink multiple PSS chains to form a dense three-dimensional network, improving the water and heat resistance of the film, and can also serve as a flexible spacer arm. Then, through the esterification reaction in step 4), hydroxyl-containing hindered phenolic antioxidant functional groups and phosphite antioxidant functional groups are covalently grafted to the hydroxyl sites generated by the epoxy ring-opening, ultimately achieving stable anchoring of antioxidant groups in the PEDOT:PSS system, preventing the migration and precipitation of small molecule antioxidants. At the same time, the hindered phenols can capture oxidative free radicals, and the phosphites decompose hydrogen peroxides. The two work synergistically to improve the long-term thermal and oxygen stability of the conductive film.

[0052] Example 2

[0053] In this embodiment, only 3,5-di-tert-butyl-4-hydroxybenzoic acid is grafted onto PEDOT:PSS; the other parts are the same as in Example 1.

[0054] Example 3

[0055] In this embodiment, only monocarboxyphenyl phosphite is grafted onto PEDOT:PSS; the other parts are the same as in Example 1.

[0056] Comparative Example 1

[0057] In Comparative Example 1, no hindered phenolic antioxidant functional groups or phosphite antioxidant functional groups were grafted onto the PEDOT:PSS core of the solid aluminum electrolytic capacitor. The rest of this example is the same as in Example 1.

[0058] Twenty products each from Example 1, Example 2, Example 3, and Comparative Example 1 were prepared, with parameters of 16V and 330µF. Their average initial capacity, average internal resistance, and average capacity retention after aging at 105°C for 8000 hours were tested. The results are shown in the table below.

[0059] Average initial capacity (μF) Average internal resistance (mΩ) Average capacity retention rate (%) after aging at 105℃ for 8000 hours Example 1 347 12.5 85.6 Example 2 353 13.6 71.1 Example 3 358 13.3 72.6 Comparative Example 1 357 14.8 65.3

[0060] As can be seen from the table above, the stability of the solid aluminum electrolytic capacitor in Example 1 can meet the stringent requirements of AI server power supplies.

Claims

1. A stable solid aluminum electrolytic capacitor, comprising a core and a casing, wherein the core is sealed within the casing by a sealing element; a conductive polymer is formed within the core, characterized in that: The conductive polymer includes PEDOT:PSS grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups.

2. The stable solid aluminum electrolytic capacitor according to claim 1, characterized in that: The amount of hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups grafted onto PEDOT:PSS is 0.5%-10% of the weight of PEDOT:PSS.

3. The stable solid aluminum electrolytic capacitor according to claim 1, characterized in that: The hindered phenolic antioxidant functional groups include one or more of 3,5-di-tert-butyl-4-hydroxybenzoic acid, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 3,5-di-tert-butyl-4-hydroxyphenyl acrylate, 3,5-di-tert-butyl-4-hydroxystyrene, and 3-tert-butyl-5-methyl-4-hydroxyphenylpropionic acid.

4. The stable solid aluminum electrolytic capacitor according to claim 1, characterized in that: The antioxidant functional groups of the phosphites include one or more of monocarboxyphenyl phosphites, dicarboxyphosphites, hydroxyalkylaryl phosphites, and polyol-type phosphites.

5. A method for preparing a solid aluminum electrolytic capacitor with good stability, characterized in that, Includes the following steps: 1) PEDOT: PSS grafts hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups; 2) Disperse the EDOT monomer grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups obtained in step 1 into deionized water, then add PSS, and add ammonium persulfate dropwise. Polymerize at 0-10℃ for 12-36 hours to obtain PEDOT:PSS grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups; the molar ratio of EDOT to PSS is 1:2-1:5; the molar ratio of ammonium persulfate to EDOT is 1:1-2:

1. 3) The core contains the PEDOT:PSS dispersion grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups from step 2). 4) Assemble to form a solid aluminum electrolytic capacitor.

6. The method for preparing a stable solid aluminum electrolytic capacitor according to claim 5, characterized in that: Step 1) includes the following steps: 1.1) Mix EDOT monomers and hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups evenly according to a preset ratio; 1.2) Add a catalyst to the mixed solution in step 1.1) and react under nitrogen protection for 12-24 hours at a reaction temperature of 50-80℃; the catalyst includes N,N'-dicyclohexylcarbodiimide and / or p-dimethylaminopyridine; 1.3) The reactants obtained in step 1.2) are filtered and subjected to column chromatography to obtain EDOT monomers grafted with hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups.

7. A method for preparing a solid aluminum electrolytic capacitor with good stability, characterized in that, Includes the following steps: a) Add PEDOT:PSS to deionized water and disperse evenly; Add epoxy crosslinking agent; b) The core contains the PEDOT:PSS dispersion impregnated in step 1); c) Dry the core package from step 2) at a temperature of 80-140°C; d) The core from step 3) comprises a condensation system containing hindered phenolic antioxidant functional groups and / or phosphite antioxidant functional groups; dried; e) Assemble to form a solid aluminum electrolytic capacitor.

8. The method for preparing a stable solid aluminum electrolytic capacitor according to claim 7, characterized in that: The epoxy crosslinking agent includes glyceryl glycidyl ether and / or polyethylene glycol diglycidyl ether.