A capacitor impregnation monomer composition and a method for producing the same, a conductive polymer, an electrolytic capacitor

Abstract

In order to overcome the problem of insufficient conductivity of the conductive polymer in the existing electrolytic capacitor, the application provides a capacitor impregnation monomer composition, which comprises the following components: a p-type conductive polymer monomer, an n-type conductive polymer monomer and a solvent; the UV-Vis spectrum of the capacitor impregnation monomer composition has an absorption peak greater than 0.1 AU between the wavelengths of 430 nm and 530 nm. Meanwhile, the application also discloses a preparation method of the capacitor impregnation monomer composition, a conductive polymer and an electrolytic capacitor. The capacitor impregnation monomer composition provided by the application can effectively reduce the ESR (equivalent series resistance) of the electrolytic capacitor.

Description

Technical Field

[0001] This invention belongs to the field of capacitor material technology, specifically relating to a monomer composition for capacitor impregnation and its preparation method, a conductive polymer, and an electrolytic capacitor. Background Technology

[0002] Solid electrolytic capacitors use solid conductive materials with high conductivity and excellent thermal stability as the electrolyte. Compared with liquid electrolytic capacitors, they have better reliability and longer lifespan, making them suitable for high-end electronic products. One current process for manufacturing solid-state capacitors is in-situ polymerization, which involves the following steps: foil opening, riveting, winding, pretreatment, carbonization, monomer impregnation, oxidant impregnation, polymerization, sealing, and formation. Currently, the monomer used is mostly 3,4-vinyldioxythiophene (EDOT).

[0003] Currently, most solid-liquid hybrid or solid aluminum electrolytic capacitors in the capacitor industry use PEDOT as the conductive polymer. PEDOT is a p-type doped conductive polymer material that conducts electricity through cation carriers (holes). In capacitor applications, its conductivity is typically less than 500 S / cm, and the equivalent series resistance (ESR) of a capacitor largely depends on the conductivity of the conductive polymer. Another type of conductive polymer, n-type conductive polymers such as polybenzodifurandione, has superior performance compared to p-type conductive polymers, but there is still significant room for improvement in its conductivity. Summary of the Invention

[0004] To address the problem of insufficient conductivity of conductive polymers in existing electrolytic capacitors, this invention provides a monomer composition for capacitor impregnation, its preparation method, a conductive polymer, and an electrolytic capacitor.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] On one hand, the present invention provides a monomer composition for impregnation of capacitors, comprising the following components:

[0007] p-type conductive polymer monomers, n-type conductive polymer monomers and solvents;

[0008] The UV-Vis spectrum of the capacitor impregnation monomer composition has an absorption peak greater than 0.1 AU between wavelengths of 430 nm and 530 nm.

[0009] Optionally, the monomer composition for impregnating the capacitor comprises the following components by weight:

[0010] 1-40 parts of p-type conductive polymer monomer, 0.01-5 parts of n-type conductive polymer monomer, and 55-99 parts of solvent.

[0011] Optionally, the monomer composition for impregnating the capacitor comprises the following components by weight:

[0012] 3-30 parts of p-type conductive polymer monomer, 0.1-4 parts of n-type conductive polymer monomer, and 55-90 parts of solvent.

[0013] Optionally, the p-type conductive polymer monomer includes one or more of acetylene and its derivatives, aniline and its derivatives, pyrrole and its derivatives, and thiophene and its derivatives.

[0014] Optionally, the p-type conductive polymer monomer is selected from 3,4-vinyldioxythiophene.

[0015] Optionally, the n-type conductive polymer monomer includes one or more of benzo[1,2-b:4,5-b"]difuran-2,6(3H,7H)-dione, benzo[1,2-b:4,5-b"]dithiophene-2,6(3H,7H)-dione, benzo[1,2-b:4,5-b"]dipyrrole-2,6(3H,7H)-dione, and their derivatives.

[0016] Optionally, the monomer composition for impregnating the capacitor is treated as follows:

[0017] The monomer composition used for impregnating the capacitor is brought into full contact with an oxygen-containing atmosphere, wherein the volume percentage of oxygen in the oxygen-containing atmosphere is ≥21%.

[0018] In another aspect, the present invention provides a method for preparing the monomer composition for capacitor impregnation as described above, comprising the following operations:

[0019] p-type conductive polymer monomers and n-type conductive polymer monomers are dispersed in an organic solvent to obtain a monomer solution;

[0020] The monomer solution is placed in an oxygen-containing atmosphere for 1-96 hours until it changes from colorless and transparent to light red, and / or an oxygen-containing atmosphere is introduced into the monomer solution until it changes from colorless and transparent to light red, to obtain a monomer composition for capacitor impregnation, wherein the volume percentage of oxygen in the oxygen-containing atmosphere is ≥21%.

[0021] In another aspect, the present invention provides a conductive polymer prepared from the capacitor impregnation monomer composition described above in combination with an oxidizing agent.

[0022] In another aspect, the present invention provides an electrolytic capacitor, comprising an anode foil having a dielectric layer on its surface, a cathode foil, electrolytic paper disposed between the anode foil and the cathode foil, and a conductive polymer as described above or a conductive polymer prepared from a capacitor impregnation monomer composition as described above, which is in contact with the dielectric layer.

[0023] The capacitor impregnation monomer composition provided by the present invention, compared with the existing method of preparing capacitor conductive polymers by simply using p-type or n-type conductive polymer monomers, simultaneously uses p-type and n-type conductive polymer monomers for mixing. During the polymerization process, the polymer segments formed by the p-type and n-type conductive polymer monomers intertwine with each other, thereby forming a conductive polymer doped with p-type and n-type monomers. Experiments have shown that compared with conductive polymers of a single conductive type, the conductive polymer doped with p-type and n-type monomers has better conductivity. Therefore, the capacitors obtained by impregnation using this capacitor impregnation monomer composition have low ESR (equivalent series resistance). In addition, the capacitor impregnation monomer composition is oxidized to a certain extent to contain compounds with absorption peaks in the 400-580 nm range. These compounds can better control the polymer, resulting in better polymer regularity, improved conductivity, and better reduction of ESR. Attached Figure Description

[0024] Figure 1 These are the UV-Vis spectra of the capacitor impregnation monomer compositions provided in Embodiment 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0025] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0026] An embodiment of the present invention provides a monomer composition for impregnation of capacitors, comprising the following components:

[0027] p-type conductive polymer monomers, n-type conductive polymer monomers and solvents;

[0028] The UV-Vis spectrum of the capacitor impregnation monomer composition has an absorption peak greater than 0.1 AU between wavelengths of 430 nm and 530 nm.

[0029] Compared to existing methods that use only p-type or n-type conductive polymer monomers to prepare conductive polymers for capacitors, this invention simultaneously uses a mixture of p-type and n-type conductive polymer monomers. During polymerization, the polymeric segments formed by the p-type and n-type conductive polymer monomers intertwine, resulting in a p-type and n-type doped conductive polymer. Experiments have shown that, compared to conductive polymers with a single conductive type, the p-type and n-type doped conductive polymer exhibits superior conductivity. Consequently, capacitors impregnated using this monomer composition for capacitor impregnation exhibit low ESR. The monomer composition for capacitor impregnation contains a compound with an absorption peak in the 400-580 nm range. This compound can effectively control the polymer, resulting in better polymer regularity, increased conductivity, and further reduced ESR.

[0030] In some embodiments, the UV-Vis spectrum of the capacitor impregnation monomer composition has an absorption peak greater than 0.3 AU between wavelengths of 430 nm and 530 nm.

[0031] In some embodiments, the capacitor impregnation monomer composition comprises the following components by weight:

[0032] 1-40 parts of p-type conductive polymer monomer, 0.01-5 parts of n-type conductive polymer monomer, and 55-99 parts of solvent.

[0033] In a specific embodiment, the weight percentage of the p-type conductive polymer monomer in the capacitor impregnation monomer composition can be 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 11 parts, 14 parts, 16 parts, 20 parts, 21 parts, 24 parts, 26 parts, 30 parts, 38 parts, or 40 parts. The weight percentage of the n-type conductive polymer monomer can be 0.01 parts, 0.05 parts, 0.08 parts, 0.1 parts, 0.5 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts, 3 parts, 3.2 parts, 3.5 parts, 3.8 parts, 4 parts, 4.5 parts, or 5 parts. The solvent can be in the following weight percentages: 55, 59, 65, 68, 71, 74, 76, 78, 79, 80, 81, 84, 88, 90, 91, 94, 98, or 99.

[0034] If the content of the p-type conductive polymer monomer or the n-type conductive polymer monomer in the monomer composition for impregnation of the capacitor is too low, the conductivity of the conductive polymer formed by the two will not be significantly improved. For example, if the content of the p-type conductive polymer monomer is too low, the properties of the obtained conductive polymer will be more inclined towards the n-type conductive polymer; if the content of the n-type conductive polymer monomer is too low, the properties of the obtained conductive polymer will be more inclined towards the p-type conductive polymer.

[0035] In a preferred embodiment, the capacitor impregnation monomer composition comprises the following components by weight:

[0036] 3-30 parts of p-type conductive polymer monomer, 0.1-4 parts of n-type conductive polymer monomer, and 55-90 parts of solvent.

[0037] When the monomer composition for capacitor impregnation meets the above ratio, the conductive polymer obtained by polymerizing the monomer composition for capacitor impregnation has better conductivity and higher structural stability. It maintains better electrical performance during long-term cycling, which helps to reduce the ESR of electrolytic capacitors and extend their service life.

[0038] In some embodiments, the p-type conductive polymer monomer includes one or more of acetylene and its derivatives, aniline and its derivatives, pyrrole and its derivatives, and thiophene and its derivatives.

[0039] In a preferred embodiment, the p-type conductive polymer monomer is selected from thiophene and its derivatives.

[0040] In a more preferred embodiment, the p-type conductive polymer monomer is selected from 3,4-vinyldioxythiophene.

[0041] Compared to other p-type conductive polymer monomers, the 3,4-vinyldioxythiophene has a higher affinity for n-type conductive polymer monomers, which can ensure the uniformity of entanglement between p-type and n-type conductive polymer monomers and avoid the problem of high local impedance caused by uneven doping.

[0042] In some embodiments, the n-type conductive polymer monomer includes one or more of benzo[1,2-b:4,5-b"]difuran-2,6(3H,7H)-dione, benzo[1,2-b:4,5-b"]dithiophene-2,6(3H,7H)-dione, benzo[1,2-b:4,5-b"]dipyrrole-2,6(3H,7H)-dione, and their derivatives.

[0043] In some embodiments, the solvent is selected from one or more of the following: alcohol solvents, ether solvents, sulfone solvents, amide solvents, imide solvents, ketone solvents, lipid solvents, aromatic solvents, aliphatic hydrocarbon solvents, halogenated hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.

[0044] In some embodiments, the solvent is selected from one or more of methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, isobutanol, propylene glycol, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dimethylacetamide, tetrahydrofuran, methyltetrahydrofuran, dichloromethane, 1,2-dichloroethane, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, butyl propionate, methyl methacrylate, toluene, xylene, trimethylbenzene, acetonitrile, acetic acid, propionic acid, acetone, butanone, cyclohexanone, methyl butanone, propionic acid, pyridine, phenol, N-methylpyrrolidone, ethylene glycol monomethyl ether, triethylamine, and γ-butyrolactone.

[0045] In some embodiments, the capacitor impregnation monomer composition is treated as follows:

[0046] The monomer composition used for impregnating the capacitor is brought into full contact with an oxygen-containing atmosphere, wherein the volume percentage of oxygen in the oxygen-containing atmosphere is ≥21%.

[0047] Compared to directly mixing p-type and n-type conductive polymer monomers, the inventors unexpectedly discovered during research and development that after preparing the monomer solution containing the two monomers, placing it in an oxygen-containing atmosphere for a certain period of time caused the monomer solution to change from colorless and transparent to light red. This indicates that the oxygen-containing atmosphere reacted with the monomers in the monomer solution and formed byproducts. More unexpectedly, after using this light red capacitor impregnation monomer composition for capacitor impregnation, it was found that the electrolytic capacitor prepared from this capacitor impregnation monomer composition placed in an oxygen-containing atmosphere had a lower ESR compared to directly mixing p-type and n-type conductive polymer monomers. The mechanism is not entirely clear, but it is speculated that the light red byproducts generated by the reaction with oxygen play a role in improving the entanglement uniformity of the p-type and n-type conductive polymer monomers, or in connecting the two conductive polymers, ultimately leading to an improvement in the conductivity of the conductive polymer.

[0048] In some embodiments, the method of contacting the capacitor impregnation monomer composition with an oxygen-containing atmosphere may be: placing the mixed monomer solution in an oxygen-containing atmosphere for 1-96 hours under normal pressure, so that the oxygen in the oxygen-containing atmosphere enters the monomer solution through dissolution and diffusion to react; in other embodiments, in order to shorten the reaction time, the oxygen-containing atmosphere may be directly introduced into the monomer solution to ensure that the oxygen in the oxygen-containing atmosphere is in full contact with the monomer solution and promote the reaction.

[0049] Another embodiment of the present invention provides a method for preparing the monomer composition for capacitor impregnation as described above, comprising the following operations:

[0050] p-type conductive polymer monomers and n-type conductive polymer monomers are dispersed in an organic solvent to obtain a monomer solution;

[0051] The monomer solution is placed in an oxygen-containing atmosphere for 1-96 hours until it changes from colorless and transparent to light red, and / or an oxygen-containing atmosphere is introduced into the monomer solution until it changes from colorless and transparent to light red, to obtain a monomer composition for capacitor impregnation, wherein the volume percentage of oxygen in the oxygen-containing atmosphere is ≥21%.

[0052] In some embodiments, the monomer solution is stirred while being placed in an oxygen-containing atmosphere.

[0053] Another embodiment of the present invention provides a conductive polymer prepared from the capacitor impregnation monomer composition described above in combination with an oxidant.

[0054] The molar ratio of the polymer monomer to the oxidant is 1:(0.5-10), and the oxidant includes one or more of oxygen, peroxide, metal halide, persulfate, perborate, hypohalate, halide, quinone compounds, and perbenzoic acid compounds.

[0055] In a preferred embodiment, the oxidant is selected from ferric methylbenzenesulfonate.

[0056] In some embodiments, the oxidant is dissolved in a solvent to form an oxidant solution for use. The solvent of the oxidant solution includes one or more of water, alcohol solvents, ether solvents, sulfone solvents, amide solvents, imine solvents, ketone solvents, lipid solvents, aromatic solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents. The total mass concentration of the oxidant solute is 3% to 60% based on 100% of the total mass of the oxidant solution.

[0057] In specific embodiments, with the total mass of the oxidant solution as 100%, the total mass concentration of the oxidant solute is 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 27%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 37%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 47%, 49%, 50%, 51%, 52%, 55%, or 60%.

[0058] If the total mass concentration of the oxidant is too low, it will affect the polymerization efficiency and film quality of the monomers, reducing production efficiency; if the total mass concentration of the oxidant is too high, it will cause the monomers to polymerize too quickly, making it difficult to carry out the impregnation operation.

[0059] Another embodiment of the present invention provides an electrolytic capacitor, comprising an anode foil having a dielectric layer on its surface, a cathode foil, electrolytic paper disposed between the anode foil and the cathode foil, and a conductive polymer as described above or a conductive polymer prepared from a capacitor impregnation monomer composition as described above, in contact with the dielectric layer.

[0060] Another embodiment of the present invention provides a method for preparing the electrolytic capacitor as described above, comprising the following operations:

[0061] (1) A monomer composition for capacitor impregnation was prepared by the preparation method described above.

[0062] (2) Preparation of oxidant solution: Dissolve the oxidant in a solvent to obtain an oxidant solution. The solute can be a single component or a combination of two components.

[0063] (3) Immerse the capacitor elements or anode foil in the capacitor impregnation monomer composition, then remove and dry.

[0064] (4) Immerse the dried capacitor elements or anode foil from step (3) in an oxidant solution, remove them, and heat them to polymerize.

[0065] (5) Steps (3) and (4) can be repeated 1 to 5 times to enhance and improve performance.

[0066] (6) Assemble the electrolytic capacitor.

[0067] The present invention will be further illustrated by the following examples.

[0068] Example 1

[0069] This embodiment illustrates the electrolytic capacitor and its preparation method disclosed in this invention, including the following steps:

[0070] (1) Cut the positive electrode foil, electrolytic paper, and negative electrode foil to the corresponding width, and wind them in sequence into a first winding body of the required specifications. Weld the first winding body to a stainless steel strip, then place it in a forming solution for initial forming treatment. After removal, dry it. Repeat the above process of "initial forming treatment followed by drying treatment" twice to obtain a second winding body. The forming treatment involves immersing the first winding body in a forming solution and then applying a forming voltage of 25VF. The forming solution is used to repair and form a new dielectric alumina film. In this embodiment, the forming solution is an 8% (w / w) ferric adipic acid aqueous solution.

[0071] (2) Dissolve (3,4-dioxyethylene)thiophene (25wt%) and 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (0.1wt%) in ethanol (74.9wt%), stir to dissolve, and place in an oxygen-containing atmosphere with an oxygen volume ratio of 21% for 24h to obtain a monomer composition for capacitor impregnation; dissolve ferric p-toluenesulfonate (60wt%) in ethanol (40wt%), stir to dissolve to obtain an oxidizing agent solution; place the second winding body in the monomer composition for capacitor impregnation, impregnate at room temperature and pressure for 3min, then dry at 55℃ for 25min, cool in air for 10min, then place in the oxidizing agent solution, impregnate at room temperature and pressure under -80kPa pressure for 5min using a vacuum impregnation device, and then dry at 40℃, 60℃, 80℃, 100℃, and 150℃ for 1h respectively to obtain the third winding body;

[0072] (3) Fix the third winding body in the aluminum shell, assemble and seal it to obtain a semi-finished capacitor, and charge and age the semi-finished capacitor to obtain a finished solid electrolytic capacitor.

[0073] Example 2

[0074] This embodiment illustrates the electrolytic capacitor and its preparation method disclosed in this invention, including most of the operational steps in Embodiment 1, with the following differences:

[0075] In step (2), the method for preparing the monomer composition for capacitor impregnation is as follows:

[0076] Acetylene (25 wt%) and 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (0.1 wt%) were dissolved in ethanol (74.9 wt%), stirred until dissolved, and placed in an oxygen-containing atmosphere with an oxygen volume of 21% for 24 h to obtain a monomer composition for capacitor impregnation.

[0077] Example 3

[0078] This embodiment illustrates the electrolytic capacitor and its preparation method disclosed in this invention, including most of the operational steps in Embodiment 1, with the following differences:

[0079] In step (2), the method for preparing the monomer composition for capacitor impregnation is as follows:

[0080] Aniline (25 wt%) and 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (0.1 wt%) were dissolved in ethanol (74.9 wt%), stirred until dissolved, and placed in an oxygen-containing atmosphere with an oxygen volume of 21% for 24 h to obtain a monomer composition for capacitor impregnation.

[0081] Example 4

[0082] This embodiment illustrates the electrolytic capacitor and its preparation method disclosed in this invention, including most of the operational steps in Embodiment 1, with the following differences:

[0083] In step (2), the method for preparing the monomer composition for capacitor impregnation is as follows:

[0084] Pyrrole (25 wt%) and 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (0.1 wt%) were dissolved in ethanol (74.9 wt%), stirred until dissolved, and placed in an oxygen-containing atmosphere with an oxygen volume of 21% for 24 h to obtain a monomer composition for capacitor impregnation.

[0085] Example 5

[0086] This embodiment illustrates the electrolytic capacitor and its preparation method disclosed in this invention, including most of the operational steps in Embodiment 1, with the following differences:

[0087] In step (2), the method for preparing the monomer composition for capacitor impregnation is as follows:

[0088] (3,4-dioxyethylene)thiophene (25 wt%) and 3,7-dihydrobenzo[1,2-b:4,5-b']dithiophene-2,6-dione (0.1 wt%) were dissolved in ethanol (74.9 wt%), stirred until dissolved, and placed in an oxygen-containing atmosphere with an oxygen volume of 21% for 24 h to obtain a monomer composition for capacitor impregnation.

[0089] Example 6

[0090] This embodiment illustrates the electrolytic capacitor and its preparation method disclosed in this invention, including most of the operational steps in Embodiment 1, with the following differences:

[0091] In step (2), the method for preparing the monomer composition for capacitor impregnation is as follows:

[0092] (3,4-dioxyethylene)thiophene (1 wt%) and 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (5 wt%) were dissolved in ethanol (94 wt%), stirred until dissolved, and placed in an oxygen-containing atmosphere with an oxygen volume of 21% for 24 h to obtain a monomer composition for capacitor impregnation.

[0093] Example 7

[0094] This embodiment illustrates the electrolytic capacitor and its preparation method disclosed in this invention, including most of the operational steps in Embodiment 1, with the following differences:

[0095] In step (2), the method for preparing the monomer composition for capacitor impregnation is as follows:

[0096] (3,4-dioxyethylene)thiophene (40 wt%) and 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (0.01 wt%) were dissolved in ethanol (59.99 wt%), stirred until dissolved, and placed in an oxygen-containing atmosphere with an oxygen volume of 21% for 24 h to obtain a monomer composition for capacitor impregnation.

[0097] Example 8

[0098] This embodiment illustrates the electrolytic capacitor and its preparation method disclosed in this invention, including most of the operational steps in Embodiment 1, with the following differences:

[0099] In step (2), the method for preparing the monomer composition for capacitor impregnation is as follows:

[0100] (3,4-dioxyethylene)thiophene (30 wt%) and 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (1 wt%) were dissolved in ethanol (69 wt%), stirred until dissolved, and placed in an oxygen-containing atmosphere with an oxygen volume of 21% for 24 h to obtain a monomer composition for capacitor impregnation.

[0101] Example 9

[0102] This embodiment illustrates the electrolytic capacitor and its preparation method disclosed in this invention, including most of the operational steps in Embodiment 1, with the following differences:

[0103] In step (2), the method for preparing the monomer composition for capacitor impregnation is as follows:

[0104] (3,4-dioxyethylene)thiophene (25 wt%) and 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (0.1 wt%) were dissolved in ethanol (74.9 wt%), stirred until dissolved, and placed in an oxygen-containing atmosphere with an oxygen volume of 80% for 24 h to obtain a monomer composition for capacitor impregnation.

[0105] Comparative Example 1

[0106] This embodiment illustrates the electrolytic capacitor and its preparation method disclosed in this invention, including most of the operational steps in Embodiment 1, with the following differences:

[0107] In step (2), the method for preparing the monomer composition for capacitor impregnation is as follows:

[0108] (3,4-dioxyethylene)thiophene (25 wt%) and 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (0.1 wt%) were dissolved in ethanol (74.9 wt%), stirred until dissolved, and placed under a nitrogen atmosphere for 24 h to obtain a monomer composition for capacitor impregnation.

[0109] Comparative Example 2

[0110] This comparative example is used to illustrate the electrolytic capacitor and its preparation method disclosed in this invention, including most of the operational steps in Example 1, with the following differences:

[0111] In step (2), the method for preparing the monomer composition for capacitor impregnation is as follows:

[0112] (3,4-dioxyethylene)thiophene (25 wt%) was dissolved in ethanol (75 wt%), stirred until dissolved, and placed in an oxygen-containing atmosphere with an oxygen volume of 21% for 24 h to obtain a monomer composition for capacitor impregnation.

[0113] Comparative Example 3

[0114] This comparative example is used to illustrate the electrolytic capacitor and its preparation method disclosed in this invention, including most of the operational steps in Example 1, with the following differences:

[0115] In step (2), the method for preparing the monomer composition for capacitor impregnation is as follows:

[0116] 3,7-Dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (25 wt%) was dissolved in ethanol (75 wt%), stirred until dissolved, and placed in an oxygen-containing atmosphere with an oxygen volume of 21% for 24 h to obtain a monomer composition for capacitor impregnation.

[0117] The method for preparing the oxidizing agent solution is as follows:

[0118] Tetramethyl-p-benzoquinone (60 wt%) was dissolved in ethanol (40 wt%) and stirred to obtain an oxidizing agent solution.

[0119] Performance testing

[0120] 1. The monomer compositions used for impregnating capacitors in Example 1 and Comparative Example 1 were subjected to UV-Vis spectroscopy analysis, and the test results are as follows: Figure 1 As shown.

[0121] 2. The electrolytic capacitors prepared above were subjected to the following relevant electrical performance tests.

[0122] According to GB / T 6346.25-2018 "Fixed Capacitors for Electronic Equipment - Part 25: Subspecification of Surface Mount Conductive Polymer Solid Electrolyte Aluminum Fixed Capacitors", the capacitance (CAP), loss tangent (DF), equivalent series resistance (ESR), and leakage current (LC) were tested. The test conditions for capacitance and loss tangent were 20℃ and 120Hz, the test conditions for equivalent series resistance were 20℃ and 100kHz, and the test conditions for leakage current were 20℃ and 2min.

[0123] The test results are entered into Table 1.

[0124] Table 1

[0125]

[0126] Comparing the test results of Examples 1, 2, 3, and 4, it can be seen that using the p-type conductive polymer monomer (3,4-dioxyethylene)thiophene is optimal; comparing the test results of Examples 1 and 5, it can be seen that using the n-type conductive polymer monomer 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione is not significantly different from 3,7-dihydrobenzo[1,2-b:4,5-b']dithiophene-2,6-dione; comparing the test results of Examples 1, 6, 7, and 8, it can be seen that using the n-type conductive polymer monomer 3,7- The optimal amount of dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione is greater than 0.5%. Comparative results from Examples 1 and 9 and Comparative Example 1 show that, within the same stirring time, a higher oxygen concentration yields better results. Comparative results from Examples 1 and Comparative Examples 2 and 3 show that adding the n-type conductive polymer monomer 3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione to the monomer solution in a mixture with the n-type conductive polymer monomer is optimal.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A monomer composition for impregnating capacitors, characterized in that, Includes the following components by weight: 1-40 parts of p-type conductive polymer monomer, 0.01-5 parts of n-type conductive polymer monomer, and 55-99 parts of solvent; and the UV-Vis spectrum of the monomer composition used for impregnation of the capacitor has an absorption peak greater than 0.1 AU between wavelengths of 430 nm and 530 nm. The p-type conductive polymer monomer includes one or more of acetylene, aniline, pyrrole, and 3,4-vinyldioxothiophene. The n-type conductive polymer monomer includes one or more of benzo[1,2-b:4,5-b"]difuran-2,6(3H,7H)-dione, benzo[1,2-b:4,5-b"]dithiophene-2,6(3H,7H)-dione, and benzo[1,2-b:4,5-b"]dipyrrole-2,6(3H,7H)-dione.

2. The monomer composition for capacitor impregnation according to claim 1, characterized in that, The capacitor impregnation monomer composition comprises the following components by weight: 3-30 parts of p-type conductive polymer monomer, 0.1-4 parts of n-type conductive polymer monomer, and 55-90 parts of solvent.

3. The monomer composition for capacitor impregnation according to claim 1, characterized in that, The capacitor impregnation monomer composition is treated as follows: The monomer composition used for impregnating the capacitor is brought into full contact with an oxygen-containing atmosphere, wherein the volume percentage of oxygen in the oxygen-containing atmosphere is ≥21%.

4. The method for preparing the monomer composition for capacitor impregnation according to any one of claims 1 to 3, characterized in that, Includes the following operations: p-type conductive polymer monomers and n-type conductive polymer monomers are dispersed in an organic solvent to obtain a monomer solution; The monomer solution is placed in an oxygen-containing atmosphere for 1-96 hours until it changes from colorless and transparent to light red, and / or an oxygen-containing atmosphere is introduced into the monomer solution until it changes from colorless and transparent to light red, to obtain a monomer composition for capacitor impregnation, wherein the volume percentage of oxygen in the oxygen-containing atmosphere is ≥21%.

5. A conductive polymer, characterized in that, It is prepared by combining the capacitor impregnation monomer composition as described in any one of claims 1 to 3 with an oxidizing agent.

6. An electrolytic capacitor, characterized in that, It includes an anode foil having a dielectric layer on its surface, a cathode foil, an electrolytic paper disposed between the anode foil and the cathode foil, and a conductive polymer as described in claim 5 or a conductive polymer prepared from a capacitor impregnation monomer composition as described in any one of claims 1 to 3 that is in contact with the dielectric layer.

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