High-voltage-resistant liquid aluminum electrolytic capacitor and preparation method thereof

Abstract

A high-voltage-resistant liquid aluminum electrolytic capacitor comprises a core bag, a shell and a sealing piece, and the core bag is arranged in the shell in a sealed mode through the sealing piece. The core package comprises an anode foil, electrolytic paper and a cathode foil; the anode foil, the electrolytic paper and the cathode foil are wound or folded to form a core package, and the electrolytic paper is impregnated with organic silicon epoxy resin. According to the invention, the organic silicon epoxy resin is impregnated on the electrolytic paper, the interface state of the electrolytic paper, the aluminum foil and the electrolyte is changed through the insulativity and high dielectric strength of the organic silicon epoxy resin, the activeness of positive and negative ions is reduced, the discharge of the electrolyte is delayed, and the electrolyte is delayed to reach an overload state, so that the sparking voltage of the electrolyte is improved; therefore, the withstand voltage value of the aluminum electrolytic capacitor is improved.

Description

Technical Field

[0001] The invention relates to a liquid aluminum electrolytic capacitor, and in particular to a high-voltage resistant liquid aluminum electrolytic capacitor and a preparation method thereof. Background Art

[0002] Traditional aluminum electrolytic capacitors are divided into low voltage, medium voltage, and high voltage, and the maximum rated voltage is generally 450VDC. In recent years, with the rapid rise of energy conservation, environmental protection, and new energy, the corresponding internal module voltage or output voltage of electrical appliances has increased significantly, reaching 500V, 600V, 700V, and even above 1000V. In addition, in order to improve the internal consumption of electrical appliances, some companies have also increased the module voltage of existing products. In addition, the market demand for capacitors with a rated voltage of more than 450V is increasing, leading the voltage of aluminum electrolytic capacitors to develop towards higher voltages.

[0003] At present, high-voltage aluminum electrolytic capacitor products, especially those with a rated voltage of more than 600V, are not very mature in technology. This is mainly because the higher the rated voltage, the higher the flash voltage requirement for the electrolyte, and the more viscous the electrolyte will be; and the more viscous the electrolyte is, the more difficult it will be to impregnate the electrolyte. At the same time, since the oxide film on the surface of the anode foil will inevitably form some tiny cracks during the production process, the leakage current of the aluminum electrolytic capacitor always exists; under high-voltage conditions, the cracks in the oxide film on the surface of the anode foil will magnify the defect of the leakage current, and at this time, the flash voltage performance of the electrolyte becomes particularly important. 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 high-voltage resistant liquid aluminum electrolytic capacitor and a preparation method thereof.

[0005] In order to solve the above technical problems, the technical solution proposed in the present invention is: a high-voltage resistant liquid aluminum electrolytic capacitor, comprising a core package, a shell and a seal, wherein the core package is sealed in the shell by the seal; the core package comprises an anode foil, an electrolytic paper and a cathode foil; the anode foil, the electrolytic paper and the cathode foil are wound or folded to form the core package, and the electrolytic paper is impregnated with a silicone epoxy resin.

[0006] In the above-mentioned high-voltage resistant liquid aluminum electrolytic capacitor, preferably, the organic silicon epoxy resin is evenly distributed on the electrolytic paper.

[0007] In the above-mentioned high-voltage resistant liquid aluminum electrolytic capacitor, preferably, a layer of organic silicon epoxy resin insulating film is formed on the surface of the anode foil.

[0008] A method for preparing a high-voltage resistant liquid aluminum electrolytic capacitor comprises the following steps: 1) Cut the anode foil, electrolytic paper and cathode foil into preset sizes respectively; 2) Impregnating the electrolytic paper in an organic silicon epoxy resin solution, taking it out and drying it; the weight concentration of the organic silicon epoxy resin in the organic silicon epoxy resin solution is 0.25%-0.5%, and the solvent of the organic silicon epoxy resin solution includes a mixture of one or more of thinner, o-xylene and dimethyl carbonate and ethanol; 3) Winding or folding the anode foil, electrolytic paper and cathode foil to form a core package; 4) Assembling, the core package is sealed in the shell through the sealing member.

[0009] In the method for preparing the high-voltage resistant liquid aluminum electrolytic capacitor, preferably, in step 2), the electrolytic paper is completely immersed in the silicone epoxy resin solution at a temperature between 75°C and 85°C for 30 minutes to 2 hours, and after being taken out, it is dried to evaporate the solvent and solidify the silicone epoxy resin.

[0010] In the method for preparing the high-voltage resistant liquid aluminum electrolytic capacitor, preferably, before step 3), a silicone epoxy resin is coated on the surface of the anode foil to form a layer of silicone epoxy resin insulating film.

[0011] Compared with the prior art, the advantages of the present invention are as follows: in the present invention, by impregnating the electrolytic paper with silicone epoxy resin, the insulation and high dielectric strength of the silicone epoxy resin are used to change the interface state of the electrolytic paper, the aluminum foil and the electrolyte, thereby reducing the activity of positive and negative ions, delaying the discharge of the electrolyte, and delaying the electrolyte from reaching an overload state, thereby increasing the flash voltage of the electrolyte, thereby improving the withstand voltage of the aluminum electrolytic capacitor. DETAILED DESCRIPTION

[0012] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0013] It should be noted that when an element is described as being "fixed, fixed, connected or connected to" another element, it can be directly fixed, fixed, connected or connected to the other element, or it can be indirectly fixed, fixed, connected or connected to the other element through other intermediate connectors.

[0014] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Example 1

[0015] The present embodiment provides a high-voltage resistant liquid aluminum electrolytic capacitor, comprising a core package, a shell and a seal, wherein the core package is sealed in the shell by the seal; the core package comprises an anode foil, an electrolytic paper and a cathode foil; the anode foil, the electrolytic paper and the cathode foil are wound or folded to form the core package, and the electrolytic paper is impregnated with an organic silicon epoxy resin; the organic silicon epoxy resin is evenly distributed on the electrolytic paper.

[0016] In this embodiment, the core package is impregnated with an electrolyte, and the components of the electrolyte include, by weight: 40-60 parts of a main solvent, 10-25 parts of an auxiliary solvent, 8-20 parts of a main solute, 4-10 parts of an auxiliary solute, 5-15 parts of a flash voltage enhancer, and 0.5-3 parts of a hydrogen remover.

[0017] In this embodiment, the main solvent is ethylene glycol; the auxiliary solvent is one or more of diethylene glycol, glycerol, methoxy polyethylene glycol and ethylene glycol methyl ether.

[0018] In this embodiment, the main solute is one or more of 2-methyl azelaic acid, 2,7-dimethyl suberic acid, 2-butyl suberic acid, 2,9-dimethyl sebacic acid and 1,10-dimethyl octadecanedioic acid and their ammonium salts. The auxiliary solute is one or more of benzoic acid, azelaic acid, sebacic acid and dodecanedioic acid and their ammonium salts.

[0019] In this embodiment, the flash voltage enhancer is one or more of mannitol, polyvinyl alcohol and polyethylene glycol, and the hydrogen remover is one or more of p-nitrobenzoic acid, p-nitroanisole, p-nitrobenzyl alcohol and p-nitrophenol.

[0020] In this embodiment, in order to reduce the leakage current formed by the cracks of the oxide film on the surface of the anode foil, an organic silicon epoxy resin is coated on the surface of the anode foil to form a layer of organic silicon epoxy resin insulating film. After the organic silicon epoxy resin solution is coated on the surface of the anode foil, due to the fluidity of the organic silicon epoxy resin solution, the organic silicon epoxy resin will penetrate into the cracks on the surface of the anode foil. After the organic silicon epoxy resin on the surface of the anode foil is dried, a layer of organic silicon epoxy resin insulating film will be formed, thereby reducing the leakage current formed by the cracks of the oxide film on the surface of the anode foil.

[0021] A method for preparing a high-voltage resistant liquid aluminum electrolytic capacitor comprises the following steps: 1) Cut the anode foil, electrolytic paper and cathode foil into preset sizes respectively; 2) Immerse the electrolytic paper in the silicone epoxy resin solution, take it out and dry it; the weight concentration of the silicone epoxy resin in the silicone epoxy resin solution is 0.25%-0.5%, and the solvent of the silicone epoxy resin solution includes a mixture of one or more of thinner, o-xylene and dimethyl carbonate and ethanol; when immersing, the electrolytic paper is completely immersed in the silicone epoxy resin solution, the temperature is between 75℃-85℃, and the time is 30 minutes-2 hours. After taking it out, dry it to evaporate the solvent and solidify the silicone epoxy resin. The surface of the anode foil is coated with silicone epoxy resin, and after drying, a layer of silicone epoxy resin insulating film is formed; 3) Winding or folding the anode foil, electrolytic paper and cathode foil to form a core package; 4) Assembling, the core package is sealed in the shell through the sealing member.

[0022] In the present invention, silicone epoxy resin is impregnated on the electrolytic paper, and the insulation and high dielectric strength of the silicone epoxy resin are used to change the interface state of the electrolytic paper, aluminum foil and electrolyte, reduce the activity of positive and negative ions, delay the discharge of the electrolyte, and postpone the electrolyte from reaching an overload state, thereby increasing the flash voltage of the electrolyte, thereby improving the withstand voltage of the aluminum electrolytic capacitor.

[0023] In medium and high voltage aluminum electrolytic capacitors, the surface of the anode foil is prone to creeping discharge, which refers to the phenomenon that gas and liquid are easily discharged on the solid surface. In this embodiment, the electrolytic paper is impregnated with silicone epoxy resin. When the anode foil, electrolytic paper and cathode foil are wound into a core package, the interface state between the anode foil and the electrolytic paper becomes a gel-like state, which changes the interface state, thereby delaying the discharge of gas and liquid.

[0024] After the electrolytic paper is impregnated with silicone epoxy resin, the migration ability of positive and negative ions in the electrolyte can be reduced, and the amount of electrolyte adsorbed by the electrolytic paper can be reduced, that is, the energy density of the anode foil, cathode foil and electrolyte is reduced, and the electrolyte is delayed to reach an overload state, thereby improving the withstand voltage of the electrolyte. Simply put, the silicone epoxy resin reduces the dielectric constant of the electrolyte and reduces the accumulation of positive and negative ions in the electrolyte on the surface of the anode foil and cathode foil; at the same time, the silicone epoxy resin insulating film formed on the surface of the anode foil can also reduce the leakage current formed by tiny cracks in the oxide film on the surface of the anode foil to a certain extent, thereby further improving the withstand voltage value of the liquid aluminum electrolytic capacitor. Example 2

[0025] In this embodiment, the surface of the anode foil is not coated with organic silicon epoxy resin, that is, no organic silicon epoxy resin insulating film is formed on the surface of the anode foil.

[0026] Comparative Example 1 In Comparative Example 1, the electrolytic paper is not impregnated with the organosilicon epoxy resin solution, the surface of the anode foil is not coated with the organosilicon epoxy resin, and no organosilicon epoxy resin insulating film is formed on the surface of the anode foil; the rest is the same as in Example 1.

[0027] 20 products of Example 1, Example 2 and Comparative Example 1 with specifications of 550V and 100μF were selected respectively, and their average flash voltage and leakage current were tested respectively. The results are shown in the following table: .

Claims

1. A high voltage resistant liquid aluminum electrolytic capacitor, characterized in that: The invention comprises a core package, an outer shell and a seal, wherein the core package is sealed in the outer shell by the seal; the core package comprises an anode foil, an electrolytic paper and a cathode foil; the anode foil, the electrolytic paper and the cathode foil are wound or folded to form the core package, and the electrolytic paper is impregnated with an organic silicon epoxy resin.

2. The high voltage resistant liquid aluminum electrolytic capacitor according to claim 1, characterized in that: The organosilicon epoxy resin is evenly distributed on the electrolytic paper.

3. The high voltage resistant liquid aluminum electrolytic capacitor according to claim 1 or 2, characterized in that: A layer of organic silicon epoxy resin insulating film is formed on the surface of the anode foil.

4. A method for preparing a high-voltage resistant liquid aluminum electrolytic capacitor, characterized in that: The steps include: 1) Cut the anode foil, electrolytic paper and cathode foil into preset sizes respectively; 2) Impregnating the electrolytic paper in an organic silicon epoxy resin solution, taking it out and drying it; the weight concentration of the organic silicon epoxy resin in the organic silicon epoxy resin solution is 0.25%-0.5%, and the solvent of the organic silicon epoxy resin solution includes a mixture of one or more of thinner, o-xylene and dimethyl carbonate and ethanol; 3) Winding or folding the anode foil, electrolytic paper and cathode foil to form a core package; 4) Assembling, the core package is sealed in the shell through the sealing member.

5. The method for preparing a high-voltage resistant liquid aluminum electrolytic capacitor according to claim 4, characterized in that: In the step 2), the electrolytic paper is completely immersed in the organic silicon epoxy resin solution at a temperature between 75°C and 85°C for 30 minutes to 2 hours. After being taken out, it is dried to evaporate the solvent and solidify the organic silicon epoxy resin.

6. The method for preparing a high voltage resistant liquid aluminum electrolytic capacitor according to claim 4, characterized in that: Prior to step 3), a silicone epoxy resin is coated on the surface of the anode foil to form a layer of silicone epoxy resin insulating film.