High-temperature-resistant electrolyte for solid-liquid mixed capacitor

Abstract

The invention provides a solid-liquid mixed capacitor high-temperature-resistant electrolyte, the electrolyte contains a solute, a solvent and an additive, the solvent is one or two of diethylene glycol and triethylene glycol, the weight of the solvent accounts for 30-90% of the weight of the whole solvent, the solute is amine salt containing 18-22 carbons, the additive is one or more of a sparking voltage boosting agent, a preservative, a hydrogen eliminating agent and a stabilizer, and the electrolyte is a high-temperature-resistant electrolyte. The sparking voltage boosting agent comprises surface adsorption type particles and resistant particles. After the scheme is adopted, the high-heat stability and the reliability are obvious, that is, the characteristic change from the initial characteristic is small even if the high-heat-resistant coating is used for a long time at a high temperature. Even after a reflow soldering process at a high temperature of more than 250 DEG C, the tin soldering operation can be carried out for more than two times, and the initial characteristics can be maintained even if the tin soldering process is used for a long time at a high temperature of more than 135 DEG C.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytes, in particular to a high temperature resistant electrolyte for aluminum electrolytic capacitors. Background Art

[0002] With the rapid development of modern electronic technology, high requirements are placed on various electronic components. Due to the advantages of high voltage resistance, large capacity, simple production process and low price, aluminum electrolytic capacitors are widely used in various electronic devices. With the development of color TVs, monitors, audio-visual equipment, and switching power supplies, the demand for aluminum electrolytic capacitors is increasing, and the requirements are also getting higher and higher. However, the existing aluminum electrolytic capacitors have low high temperature resistance, which makes the product market defective rate high and cannot meet the normal operation under the market voltage instability; in particular, the higher the rated voltage, the greater the probability of occasional failure. Summary of the invention

[0003] The object of the present invention is to provide a solid-liquid mixed capacitor high temperature resistant electrolyte for aluminum electrolytic capacitors.

[0004] To achieve the above-mentioned purpose, the technical solution provided by the present invention is: a solid-liquid hybrid capacitor high-temperature resistant electrolyte, the electrolyte containing solute, solvent and additives, the solvent is one or two of diethylene glycol and triethylene glycol, 30-90% by weight of the whole solvent, the solute is an amine salt containing 18-22 carbon atoms, the additive is one or more of a flash voltage enhancer, a preservative, a dehydrogenation agent, and a stabilizer, and the flash voltage enhancer includes two types: surface adsorption type and Nike particles.

[0005] Diethylene glycol or triethylene glycol is added to the conductive polymer aqueous dispersion in advance at a concentration of 0.5% by weight to reduce the surface tension of the dispersion and improve the dispersibility of the conductive polymer microparticles.

[0006] γ-butyrolactone alone or a mixed solvent of γ-butyrolactone and tetramethylsilane is used as the second solvent.

[0007] The solute is composed of acid and amine, wherein the acid is one or more of dodecane diacid, 2-butyl octanedioic acid, isopentanedioic acid, and dicyanic acid, and the amine is imidazole amine with a boiling point of 256° C. or an amine with an amino skeleton.

[0008] The solvent of the electrolyte does not use the commonly used ethylene glycol, but uses diethylene glycol and triethylene glycol as the main solvent. In addition, according to the purpose, γ-butyrolactone alone or a mixed solvent of γ-butyrolactone and tetramethylsilane is used as the second solvent. The amount of ethanol compounds occupied in the entire solvent is at least 30% by weight, and the preferred content is in the range of 45% to 80% by weight. The total content of diethylene glycol or / and triethylene glycol and γ-butyrolactone is 80% by weight or more, preferably 85% by weight or more, which is a feature. In addition, it is known that if polyalkylene glycol such as polyethylene glycol or its medium is added to the electrolyte, the thermal oxidation degradation of the conductive polymer can be prevented and the repairability of the medium defect can be improved under the severe high temperature use conditions of the heat overlap caused by the ripple current. In order to suppress the increase in the viscosity of the electrolyte, the average molecular weight of the added polyalkylene glycol is preferably in the range of relatively low molecular weight of 300 to 1000. If the amount added is too much, the viscosity will increase and the impregnation of the electrolyte will deteriorate, so the maximum amount is 10% by weight and the minimum amount is 3% by weight.

[0009] Amines and amino acids are used as salt bases of acids such as ammonia and salicylic acid that form composite compounds of alicyclic dicarboxylic acids such as phthalic acid, organic acids, and inorganic acids, among which alkylamines such as diethylene glycol and triethylene glycol, which are more alkaline than amino groups, are also recommended. However, the solute containing the above-mentioned acid and salt is combined with the solvent related to the present invention having diethylene glycol and triethylene glycol as main components. The specific acid and specific amine used in the present invention are as follows: the specific acid has a total carbon number of more than 12 and must be a long-chain dibasic carboxylic acid. The specific amine must be an amine with a boiling point of more than 150°C. Such long-chain dibasic carboxylic acids are preferably dienoic acids such as dodecane diacid, 2-butyloctanedioic acid, isopentanedioic acid, and dicyanic acid.

[0010] The present invention has remarkable high thermal stability and reliability after adopting the above scheme, that is, even if it is used for a long time at high temperature, the characteristic change from the initial characteristic is small. Even after the high temperature reflow process exceeding 250°C, it can withstand more than 2 soldering operations, and even if it is used for a long time at a high temperature exceeding 135°C, it can maintain the initial characteristics. DETAILED DESCRIPTION

[0011] The present invention is further described below. A solid-liquid hybrid capacitor high temperature resistant electrolyte of the present invention is characterized in that: the electrolyte contains a solute, a solvent and an additive, the solvent is one or two of diethylene glycol and triethylene glycol, accounting for 30-90% by weight of the whole solvent, the solute is an amine salt containing 18-22 carbon atoms, and the additive is a property improver of a branched electrolyte.

[0012] The solvent of the electrolyte does not use the commonly used ethylene glycol, but uses diethylene glycol and triethylene glycol as the main solvent. In addition, according to the purpose, γ-butyrolactone alone or a mixed solvent of γ-butyrolactone and tetramethylsilane is used as the second solvent. The amount of ethanol compounds occupied in the entire solvent is at least 30% by weight, and the preferred content is in the range of 45% to 80% by weight. The total content of diethylene glycol or / and triethylene glycol and γ-butyrolactone is 80% by weight or more, preferably 85% by weight or more, which is a feature. In addition, it is known that if polyalkylene glycol such as polyethylene glycol or its medium is added to the electrolyte, the thermal oxidation degradation of the conductive polymer can be prevented and the repairability of the medium defect can be improved under the severe high temperature use conditions of the heat overlap caused by the ripple current. In order to suppress the increase in the viscosity of the electrolyte, the average molecular weight of the added polyalkylene glycol is preferably in the range of relatively low molecular weight of 300 to 1000. If the amount added is too much, the viscosity will increase and the impregnation of the electrolyte will deteriorate, so the maximum amount is 10% by weight and the minimum amount is 3% by weight.

[0013] In the present invention, diethylene glycol or triethylene glycol is pre-added to the conductive polymer aqueous dispersion at a concentration of 0.3 to 3% by weight, preferably 0.5% by weight, so that the surface tension of the dispersion is reduced and the dispersibility of the conductive polymer microparticles is improved. This can enhance the permeability and wettability of the conductive polymer microparticles to the tiny corrosion pores of the aluminum oxide dielectric layer.

[0014] The solute uses amines and amino acids as salt bases of acids such as ammonia and salicylic acid that form a composite compound of alicyclic dicarboxylic acids such as phthalic acid, organic acids, and inorganic acids, among which alkylamines such as diethylene glycol and triethylene glycol that are more alkaline than amino groups are also recommended. However, the solute containing the above-mentioned acid and salt is combined with the solvent related to the present invention that uses diethylene glycol and triethylene glycol as main components. The specific acid and specific amine used in the present invention are as follows: the specific acid has a total carbon number of more than 12 and must be a long-chain dibasic carboxylic acid. The specific amine must be an amine with a boiling point of more than 150°C. Such long-chain dibasic carboxylic acids are preferably dienoic acids such as dodecane diacid, 2-butyl octanedioic acid, isopentanedioic acid, and dicyanic acid.

[0015] In addition, alkylamines such as dibutylamine (boiling point 159°C), tripropylamine (boiling point 156°C), tributylamine (boiling point 217°C), aniline (boiling point 184°C), toluidine (boiling point 200°C), N-methylaniline (boiling point 196°C), imidazole (boiling point 256°C) and its medium (including quaternary imidazolinium salt), amides with cyclic skeletons (boiling point 240°C), 12-vinyl-8-octadecene dicarboxylic acid (boiling point 261°C) and other amines with amino skeletons, and its medium amines, and its medium (including quaternary ammonium salt) and other aromatic amines and complex cyclic amine compounds are suitable as the specific ammonia mentioned here. In particular, it was confirmed that 12-vinyl-8-octadecene dicarboxylic acid (boiling point 261°C) has high thermal stability and has the effect of improving the withstand voltage (spark voltage) of the electrolyte. The amount of amine is relatively less than that of carboxylic acid, and the pH of the electrolyte is adjusted to 4-8, preferably 4-6. If too much amine is added, it will react with the dopant used for the conductive molecule, which may cause dedoping, so it needs to be as small as possible. If no amine is added, it is possible to use only carboxylic acid in the solute, but when the pH value of the electrolyte becomes 4, the carboxylic acid may deteriorate (esterification with the solvent, etc.), and the corrosion of the electrode and the chemical film may occur, so it is necessary to use amine to neutralize to a certain extent. The solute containing the salt formed by these specific acids and bases is easily dissolved in the solvent with diethylene glycol and / or triethylene glycol as the main components, so it is dissolved in the solvent constituting the electrolyte of the present invention. The concentration of the carboxylic acid and the amine in the liquid combined is 5 ~ 40%, preferably in the range of 10 ~ 25%. Thereby maintaining high pressure resistance and high temperature stability, it exists at the aluminum oxide interface of the conductive polymer and the medium, and plays a great role in the fusion of the two.

[0016] After adopting the above scheme, it has remarkable high thermal stability and reliability, that is, even if it is used for a long time at high temperature, the characteristics change little from the initial characteristics. Even after the high temperature reflow process exceeding 250℃, it can withstand more than 2 soldering operations, and even if it is used for a long time at a high temperature exceeding 135℃, it can maintain the initial characteristics.

[0017] The embodiments described above are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. Therefore, all changes made according to the shape and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A solid-liquid hybrid capacitor high temperature resistant electrolyte, characterized in that: The electrolyte contains solute, solvent and additives. The solvent is one or two of diethylene glycol and triethylene glycol, accounting for 30-90% by weight of the whole solvent. The solute is an amine salt containing 18-22 carbon atoms.

2. The solid-liquid hybrid capacitor high temperature resistant electrolyte according to claim 1, characterized in that: Diethylene glycol or triethylene glycol is added to the conductive polymer aqueous dispersion in advance at a concentration of 0.5% by weight to reduce the surface tension of the dispersion and improve the dispersibility of the conductive polymer microparticles.

3. The solid-liquid hybrid capacitor high temperature resistant electrolyte according to claim 1, characterized in that: γ-butyrolactone alone or a mixed solvent of γ-butyrolactone and tetramethylsilane was used as a solvent.

4. The solid-liquid hybrid capacitor high temperature resistant electrolyte according to claim 1, characterized in that: The solute is composed of acid and amine, wherein the acid is one or more of dodecane diacid, 2-butyl octanedioic acid, isopentanedioic acid, and dicyanic acid, and the amine is imidazole amine with a boiling point of 256° C. or an amine with an amino skeleton.

5. The solid-liquid hybrid capacitor high temperature resistant electrolyte according to claim 1, characterized in that: The additive is one or more of a flash voltage enhancer, a preservative, a dehydrogenating agent, and a stabilizer. The flash voltage enhancer includes two types: surface adsorption type and Nike particles.