Conductive polymer type solid electrolytic capacitor and preparation process thereof
The dielectric film with modified carbon nanotube loaded nanosilver particles was prepared through solution blending and hot pressing forming processes, which solved the problem of poor nanoparticle agglomeration and compatibility in traditional composite materials, and achieved high dielectric constant, low dielectric loss and high breakdown strength, improving the energy storage effect of the capacitor.
Patent Information
- Application Number
- CN202510249770.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-04
- Publication Date
- 2025-05-16
AI Technical Summary
Inorganic nanoparticles in traditional polymer-based composite dielectric materials are prone to agglomeration and have poor compatibility with polymer matrix, resulting in uneven distribution in the material, pores and defects, improved dielectric loss and decreased breakdown performance.
The dielectric film with polyvinylidene fluoride as the matrix was prepared by solution blending and hot pressing forming process. Modified carbon nanotubes were added. The carbon nanotubes were coated with polydopamine and the nanosilver particles were loaded. The hydrogen bonding between dopamine and the polymer matrix and the Coulomb blocking effect of Ag nanoparticles were used to inhibit interface polarization.
The dielectric constant of the material is successfully improved, the dielectric loss is reduced, the breakdown strength is enhanced, and the energy storage effect of the capacitor is improved.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of tantalum capacitors, and in particular relates to a conductive polymer solid electrolytic capacitor and a preparation process thereof. Background Art
[0002] Dielectric materials with high dielectric constants are essential materials for capacitors to achieve small size and reduce parasitic inductance. Traditional high dielectric constant dielectric materials are inorganic ceramic materials. Although they have high dielectric constants, they are difficult to process, have large dielectric losses, and have low breakdown strength, which seriously limits their application. On the other hand, organic dielectric materials, such as PE, PET, PP, PC, PPS, etc., have good processability, flexibility, and high breakdown strength, but their dielectric constants are usually very low. Polymer-based composite dielectric materials combine the advantages of inorganic materials and polymer materials to form new functional materials with excellent properties such as high dielectric constant, low dielectric loss, high breakdown strength, and easy processing.
[0003] At present, the main way to prepare polymer-based composite dielectric materials is to construct a percolation system by adding conductive fillers to the polymer matrix or to add ceramic fillers with high dielectric constants. These methods can significantly improve the dielectric constant of the material and obtain polymer-based composite materials with high dielectric constants. However, since inorganic particles (especially inorganic nanoparticles) are very easy to agglomerate and have poor compatibility with the polymer matrix, the traditional composite material preparation process (such as mechanical blending or solution blending) often causes the nanoparticles to be unevenly distributed in the material, or due to poor interface compatibility, pores and defects are generated inside the material, thereby increasing the dielectric loss of the material and reducing the breakdown performance. Summary of the invention
[0004] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a conductive polymer solid electrolytic capacitor and a preparation process thereof, and prepare a dielectric film with polyvinylidene fluoride as a matrix through solution blending and hot pressing molding process, thereby improving the dielectric constant of the material, and using it in a conductive polymer solid electrolytic capacitor, thereby improving the energy storage effect of the capacitor.
[0005] The purpose of the present invention can be achieved by the following technical solutions: A conductive polymer solid electrolytic capacitor comprises a capacitor core, which is formed by winding an anode foil, a dielectric film and a cathode foil. The dielectric film comprises the following raw materials in parts by weight: 50 to 80 parts of polyvinylidene fluoride and 10 to 15 parts of modified carbon nanotubes. The modified carbon nanotubes are surface-coated with polydopamine and then loaded with nanosilver particles.
[0006] Further preferably, the conductive polymer solid electrolytic capacitor also includes an aluminum shell, the capacitor core is encapsulated by the aluminum shell, the anode foil and the cathode foil are both led out through wires, and one end of the aluminum shell corresponding to the anode and cathode wires is sealed by insulating material.
[0007] Further preferably, the method for preparing the modified carbon nanotubes comprises the following steps: (1) Dissolve tris(hydroxymethyl)aminomethane in deionized water, add 0.1 mol / L hydrochloric acid to adjust the pH to 8-9, then add dopamine hydrochloride to the above solution and stir to mix evenly, then add carbon nanotube powder, stir to mix, then ultrasonically treat for 2-4 hours, and react at 60°C for 24 hours. Centrifuge, wash, filter and dry the product to obtain polydopamine-modified carbon nanotubes: (2) adding nano silver powder to a mixture of anhydrous ethanol and deionized water in a volume ratio of 10:1, stirring evenly and then ultrasonically dispersing for 1 to 2 hours to obtain a nano silver powder dispersion, then adding 3-aminopropyltrimethoxysilane to the dispersion, stirring and heating to 80°C for 3 to 5 hours, centrifugally washing, filtering and drying to obtain silane-modified nano silver powder; (3) Add the polydopamine-modified carbon nanotubes to N,N-dimethylformamide and ultrasonically treat for 20 to 40 minutes to form a uniform suspension, then add the silane-modified nanosilver powder obtained in step S2 to the above suspension, ultrasonically treat again for 20 to 40 minutes, then heat to 100 to 110°C, stir and react for 4 to 6 hours, centrifuge, wash, filter and dry the product to obtain modified carbon nanotubes.
[0008] Further preferably, in step (1), the mass ratio of dopamine hydrochloride to carbon nanotubes is 1:10-15.
[0009] Further preferably, in step (3), the mass ratio of the polydopamine-modified carbon nanotubes to the silane-modified nano-silver powder is 3-5:1.
[0010] The preparation process of the conductive polymer solid electrolytic capacitor includes the following steps: S1. Dissolve polyvinylidene fluoride in N,N-dimethylformamide and stir at 60°C for 1-2 hours to fully dissolve the polymer. Meanwhile, disperse the modified carbon nanotubes in N,N-dimethylformamide and perform ultrasonic treatment for 10-20 minutes while stirring to fully disperse the modified carbon nanotubes. S2, slowly adding the polyvinylidene fluoride solution to the modified carbon nanotube dispersion, stirring at room temperature for 10-12 hours, then applying the mixed slurry on a glass plate, and then drying it in an oven at 90°C for 1-3 hours to remove the solvent to obtain a PVDF / CNTs-PAD-Ag composite material; S3. The PVDF / CNTs-PAD-Ag composite material is hot-pressed at 180°C for 5-15 minutes to obtain a 40-50 μm thick dielectric film, which is cut into a suitable size and wound with the anode foil, dielectric film and cathode foil to form a capacitor core. Finally, the anode foil and cathode foil are respectively led out with wires, and the capacitor core is encapsulated in an aluminum shell to obtain a conductive polymer solid electrolytic capacitor.
[0011] Beneficial effects of the present invention: The dielectric film in the conductive polymer solid electrolytic capacitor of the present invention adopts PVDF / CNTs-PAD-Ag composite material, polyvinylidene fluoride is used as a matrix to add modified carbon nanotubes, and is prepared by solution blending and hot pressing molding process, after the surface of the carbon nanotube is coated with polydopamine, nanosilver particles are loaded, and the hydrogen bonding effect between dopamine and the polymer matrix and the Coulomb blocking effect of Ag nanoparticles are utilized to successfully inhibit the interface polarization inside the material, reduce the dielectric loss, improve the breakdown strength, and improve the dielectric constant of the material, thereby improving the energy storage effect of the capacitor. DETAILED DESCRIPTION
[0012] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0013] Embodiment 1 A method for preparing modified carbon nanotubes comprises the following steps: (1) Dissolve tris(hydroxymethyl)aminomethane in deionized water, add 0.1 mol / L hydrochloric acid to adjust the pH to 8-9, then add 1.5 g dopamine hydrochloride to the above solution and stir to mix evenly, then add 20 g carbon nanotube powder, stir to mix, then ultrasonically treat for 3 h, and react at 60 °C for 24 h. Centrifuge, wash, filter and dry the product to obtain polydopamine-modified carbon nanotubes: (2) adding nano silver powder to a mixture of anhydrous ethanol and deionized water in a volume ratio of 10:1, stirring evenly and then ultrasonically dispersing for 1 to 2 hours to obtain a nano silver powder dispersion, then adding 3-aminopropyltrimethoxysilane to the dispersion, stirring and heating to 80°C for 3 to 5 hours, centrifugally washing, filtering and drying to obtain silane-modified nano silver powder; (3) 5.2 g of polydopamine-modified carbon nanotubes were added to 30 ml of N,N-dimethylformamide and ultrasonically treated for 30 min to form a uniform suspension. Then 1.5 g of silane-modified nanosilver powder obtained in step S2 was added to the above suspension and ultrasonically treated again for 30 min. The suspension was then heated to 105° C. and stirred for reaction for 5 h. The product was centrifuged, washed, filtered and dried to obtain modified carbon nanotubes.
[0014] Example 2 A conductive polymer solid electrolytic capacitor includes a capacitor core, which is formed by winding an anode foil, a dielectric film and a cathode foil. The dielectric film includes the following raw materials in parts by weight: 60 parts of polyvinylidene fluoride and 12 parts of modified carbon nanotubes. The modified carbon nanotubes are carbon nanotubes prepared in Example 1, which are coated with polydopamine and loaded with nanosilver particles. The conductive polymer solid electrolytic capacitor also includes an aluminum shell, which is encapsulated by the capacitor core, and the anode foil and the cathode foil are both led out through wires. One end of the aluminum shell is blocked by an insulating material at the anode and cathode wires.
[0015] The preparation process of the conductive polymer solid electrolytic capacitor comprises the following steps: S1. Dissolve polyvinylidene fluoride in N,N-dimethylformamide and stir at 60° C. for 2 h to fully dissolve the polymer. Disperse the modified carbon nanotubes in N,N-dimethylformamide and perform ultrasonic treatment for 15 min while stirring to fully disperse the modified carbon nanotubes. S2, slowly adding the polyvinylidene fluoride solution to the modified carbon nanotube dispersion, stirring at room temperature for 10 hours, then applying the mixed slurry on a glass plate, and then drying it in an oven at 90°C for 2 hours to remove the solvent to obtain a PVDF / CNTs-PAD-Ag composite material; S3. The PVDF / CNTs-PAD-Ag composite material is hot-pressed at 180°C for 10 minutes to obtain a 45 μm thick dielectric film, which is cut into a suitable size and wound with the anode foil, the dielectric film and the cathode foil to form a capacitor core. Finally, the anode foil and the cathode foil are respectively led out with wires, and the capacitor core is encapsulated in an aluminum shell to obtain the conductive polymer solid electrolytic capacitor.
[0016] Example 3 A conductive polymer solid electrolytic capacitor includes a capacitor core, which is formed by winding an anode foil, a dielectric film and a cathode foil. The dielectric film includes the following raw materials in parts by weight: 50 parts of polyvinylidene fluoride and 15 parts of modified carbon nanotubes. The modified carbon nanotubes are carbon nanotubes prepared in Example 1, and the surface of the carbon nanotubes is coated with polydopamine and then loaded with nanosilver particles. The conductive polymer solid electrolytic capacitor also includes an aluminum shell, and the capacitor core is encapsulated by the aluminum shell. The anode foil and the cathode foil are both led out by wires, and one end of the aluminum shell is blocked by an insulating material at the anode and cathode wires.
[0017] The preparation process of the conductive polymer solid electrolytic capacitor comprises the following steps: S1. Dissolve polyvinylidene fluoride in N,N-dimethylformamide and stir at 60° C. for 1 hour to fully dissolve the polymer. Meanwhile, disperse the modified carbon nanotubes in N,N-dimethylformamide and perform ultrasonic treatment for 15 minutes while stirring to fully disperse the modified carbon nanotubes. S2, slowly adding the polyvinylidene fluoride solution to the modified carbon nanotube dispersion, stirring at room temperature for 11 hours, then applying the mixed slurry on a glass plate, and then drying it in an oven at 90°C for 2 hours to remove the solvent to obtain a PVDF / CNTs-PAD-Ag composite material; S3. The PVDF / CNTs-PAD-Ag composite material is hot-pressed at 180°C for 10 minutes to obtain a 45 μm thick dielectric film, which is cut into a suitable size and wound with the anode foil, the dielectric film and the cathode foil to form a capacitor core. Finally, the anode foil and the cathode foil are respectively led out with wires, and the capacitor core is encapsulated in an aluminum shell to obtain the conductive polymer solid electrolytic capacitor.
[0018] Example 4 A conductive polymer solid electrolytic capacitor includes a capacitor core, which is formed by winding an anode foil, a dielectric film and a cathode foil. The dielectric film includes the following raw materials in parts by weight: 80 parts of polyvinylidene fluoride and 10 parts of modified carbon nanotubes. The modified carbon nanotubes are carbon nanotubes prepared in Example 1, which are coated with polydopamine and loaded with nanosilver particles. The conductive polymer solid electrolytic capacitor also includes an aluminum shell, which is encapsulated by the capacitor core, and the anode foil and the cathode foil are both led out through wires. One end of the aluminum shell is blocked by an insulating material at the anode and cathode wires.
[0019] The preparation process of the conductive polymer solid electrolytic capacitor comprises the following steps: S1. Dissolve polyvinylidene fluoride in N,N-dimethylformamide and stir at 60° C. for 2 h to fully dissolve the polymer. Meanwhile, disperse the modified carbon nanotubes in N,N-dimethylformamide and perform ultrasonic treatment for 10 min while stirring to fully disperse the modified carbon nanotubes. S2, slowly adding the polyvinylidene fluoride solution to the modified carbon nanotube dispersion, stirring at room temperature for 12 hours, then applying the mixed slurry on a glass plate, and then drying it in an oven at 90°C for 1 hour to remove the solvent to obtain a PVDF / CNTs-PAD-Ag composite material; S3. The PVDF / CNTs-PAD-Ag composite material is hot-pressed at 180°C for 15 minutes to obtain a 40 μm thick dielectric film, which is cut into a suitable size and wound with the anode foil, the dielectric film and the cathode foil to form a capacitor core. Finally, the anode foil and the cathode foil are respectively led out with wires, and the capacitor core is encapsulated in an aluminum shell to obtain the conductive polymer solid electrolytic capacitor.
[0020] Comparative Example 1 A conductive polymer solid electrolytic capacitor includes a capacitor core, which is formed by winding an anode foil, a dielectric film and a cathode foil, and the dielectric film includes the following raw materials by weight: 60 parts of polyvinylidene fluoride and 12 parts of carbon nanotubes. The conductive polymer solid electrolytic capacitor also includes an aluminum shell, the capacitor core is encapsulated by the aluminum shell, the anode foil and the cathode foil are both led out by wires, and one end of the aluminum shell corresponding to the anode and cathode wires is blocked by an insulating material.
[0021] The preparation process of the conductive polymer solid electrolytic capacitor comprises the following steps: S1. Dissolve polyvinylidene fluoride in N,N-dimethylformamide and stir at 60°C for 1 hour to fully dissolve the polymer. Disperse carbon nanotubes in N,N-dimethylformamide and perform ultrasonic treatment for 20 minutes while stirring to fully disperse the carbon nanotubes. S2, slowly adding the polyvinylidene fluoride solution to the carbon nanotube dispersion, stirring at room temperature for 10 hours, then applying the mixed slurry on a glass plate, and then drying it in an oven at 90°C for 3 hours to remove the solvent to obtain a PVDF / CNTs-PAD-Ag composite material; S3. The PVDF / CNTs-PAD-Ag composite material is hot-pressed at 180°C for 15 minutes to obtain a 40 μm thick dielectric film, which is cut into a suitable size and wound with the anode foil, the dielectric film and the cathode foil to form a capacitor core. Finally, the anode foil and the cathode foil are respectively led out with wires, and the capacitor core is encapsulated in an aluminum shell to obtain the conductive polymer solid electrolytic capacitor.
[0022] Performance Testing The dielectric properties test was conducted according to the standards GB1409-88 and SJ / T 1147-93. The PVDF / CNTs-PAD-Ag composite materials prepared in Examples 2 to 4 and Comparative Example 1 were made into 2 cm diameter discs by hot pressing, and silver paste electrodes were coated on the upper and lower surfaces to measure the dielectric constant in an E4980A LCR meter. The dielectric constant is calculated using the formula: C p =e 0 e r A / dCalculated, where C represents the capacitance value of the measured sample at different frequencies, e 0 is the dielectric constant in vacuum, e r is the dielectric constant of the sample, A is the area of the silver paste electrode, and d is the thickness of the sample. The dielectric loss tangent value tanδ can be directly read in the LCR table, and the results are shown in Table 1 below: Table 1 Dielectric properties test results of PVDF / CNTs-PAD-Ag composites
[0023] It can be seen from the data in Table 1 above that the PVDF / CNTs-PAD-Ag composite materials prepared in Examples 2 to 4 of the present invention have a high dielectric constant, and the dielectric loss is also lower than that of Comparative Example 1. It can be seen that the present invention successfully suppresses the interface polarization inside the material, reduces the dielectric loss, improves the breakdown strength, and improves the dielectric constant of the material by coating the surface of the carbon nanotubes with polydopamine and then loading the nanosilver particles, utilizing the hydrogen bonding between dopamine and the polymer matrix and the Coulomb blocking effect of the Ag nanoparticles.
[0024] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.
[0025] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.
Claims
1. Conductive polymer solid electrolytic capacitor, characterized in that: The invention comprises a capacitor core, which is formed by winding an anode foil, a dielectric film and a cathode foil. The dielectric film comprises the following raw materials in parts by weight: 50 to 80 parts of polyvinylidene fluoride and 10 to 15 parts of modified carbon nanotubes. The modified carbon nanotubes are carbon nanotubes whose surfaces are coated with polydopamine and then loaded with nano silver particles.
2. The conductive polymer solid electrolytic capacitor according to claim 1, characterized in that: The conductive polymer solid electrolytic capacitor also includes an aluminum shell, the capacitor core is encapsulated by the aluminum shell, the anode foil and the cathode foil are both led out through wires, and one end of the aluminum shell corresponding to the anode and cathode wires is sealed by insulating material.
3. The conductive polymer solid electrolytic capacitor according to claim 1, characterized in that: The preparation method of the modified carbon nanotubes comprises the following steps: (1) Dissolve tris(hydroxymethyl)aminomethane in deionized water, add 0.1 mol / L hydrochloric acid to adjust the pH to 8-9, then add dopamine hydrochloride to the above solution and stir to mix evenly, then add carbon nanotube powder, stir to mix, then ultrasonically treat for 2-4 hours, and react at 60°C for 24 hours. Centrifuge, wash, filter and dry the product to obtain polydopamine-modified carbon nanotubes: (2) adding nano silver powder to a mixture of anhydrous ethanol and deionized water in a volume ratio of 10:1, stirring evenly and then ultrasonically dispersing for 1 to 2 hours to obtain a nano silver powder dispersion, then adding 3-aminopropyltrimethoxysilane to the dispersion, stirring and heating to 80°C for 3 to 5 hours, centrifugally washing, filtering and drying to obtain silane-modified nano silver powder; (3) Add the polydopamine-modified carbon nanotubes to N,N-dimethylformamide and ultrasonically treat them for 20 to 40 minutes to form a uniform suspension, then add the silane-modified nanosilver powder obtained in step S2 to the above suspension, ultrasonically treat it again for 20 to 40 minutes, and then heat it to 100 to 110° C. and stir the reaction for 4 to 6 hours. The product is centrifuged, washed, filtered and dried to obtain the modified carbon nanotubes.
4. The conductive polymer solid electrolytic capacitor according to claim 1, characterized in that: In the step (1), the mass ratio of dopamine hydrochloride to carbon nanotubes is 1:10-15.
5. The conductive polymer solid electrolytic capacitor according to claim 1, characterized in that: In the step (3), the mass ratio of the polydopamine-modified carbon nanotubes to the silane-modified nano-silver powder is 3-5:
1.
6. The process for preparing a conductive polymer solid electrolytic capacitor according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Dissolve polyvinylidene fluoride in N,N-dimethylformamide and stir at 60°C for 1-2 hours to fully dissolve the polymer. Meanwhile, disperse the modified carbon nanotubes in N,N-dimethylformamide and perform ultrasonic treatment for 10-20 minutes while stirring to fully disperse the modified carbon nanotubes. S2, slowly adding the polyvinylidene fluoride solution to the modified carbon nanotube dispersion, stirring at room temperature for 10-12 hours, then applying the mixed slurry on a glass plate, and then drying it in an oven at 90°C for 1-3 hours to remove the solvent to obtain a PVDF / CNTs-PAD-Ag composite material; S3. The PVDF / CNTs-PAD-Ag composite material is hot-pressed at 180°C for 5 to 15 minutes to obtain a 40 to 50 μm thick dielectric film, which is cut into a suitable size and wound with the anode foil, the dielectric film and the cathode foil to form a capacitor core. Finally, the anode foil and the cathode foil are respectively led out with wires, and the capacitor core is encapsulated in an aluminum shell to obtain the conductive polymer solid electrolytic capacitor.