RU2393569C1 - Work electrolyte for condenser, method of electrolyte obtainment, and aluminium condenser with electrolyte - Google Patents

Abstract

FIELD: electricity. ^ SUBSTANCE: work electrolyte includes: lactone - 30-70 wt %, two amide-containing co-solvents - 10-40 wt % each, dicarboxylic acid or its ammonium salt - 3-16 wt %, boric acid - 0.5-10 wt %, polysaccharide - 0.1-5 wt %, tertiary aliphatic amine - 1-10 wt %; additionally electrolyte includes 0-7 wt % of ethylene glycol and/or 0-6 wt % of second polyatomic alcohol as additional co-solvents, 0-5 wt % of aromatic nitro compound and 0-3.5 wt % of deionised water. Method of work electrolyte obtainment involves initial mixing of solvents and heating the mix to 40C, not higher, with continuous stirring, further addition of other components except for tertiary aliphatic amine, and component stirring till complete dissolution, followed by addition of amine and heating the mix to end temperature of 1005C with continuous stirring. Then electrolyte is forced to cool down to the temperature not exceeding 30C approximately in 15 minutes. Temperature rise rate is 2-5C per minute, and mixer rotation rate is 50-80 rpm. ^ EFFECT: obtainment of condenser operational at nominal voltage of 400-450 V in a wide temperature range from -60C to 105C. ^ 10 cl, 3 dwg

Description

The invention relates to the manufacture of electronic products, specifically to the production of aluminum electrolytic capacitors, in particular, with low impedance, operating at high nominal voltages of 400-450 V in the range of operating temperatures from minus 60 to 105 ° C.

The working electrolyte (hereinafter referred to as the electrolyte), in which the passage of electric current is carried out due to the movement of ions and is accompanied by electrolysis, ensures the performance of the capacitor at certain rated voltages in a certain range of operating temperatures, as well as the rated ripple current and the life of the capacitor. Various, often conflicting, requirements are presented to the working electrolyte:

- high electrical conductivity (hereinafter - conductivity);

- small changes in conductivity in the entire range of operating temperatures;

- good forming ability for shaping the anode, i.e. the rapid formation during training of the capacitor on an aluminum foil anode of a dielectric film of aluminum oxide along the edges and microcracks formed during cutting of the foil and winding of the capacitor element;

- high sparking voltage, which expresses the beginning process of anode breakdown of the electrolyte, and subsequently the capacitor, which should always be known to be greater than the molding voltage, which, in turn, should be greater than the rated voltage of the capacitor;

- stable performance at maximum operating temperature;

- minimized reaction reactions with the materials of the capacitor;

- stability of parameters during storage under normal conditions (hereinafter - NU);

- low toxicity and flammability.

The electrolyte-gasket-oxide system should provide good absorbency of capacitor gaskets, stability of the characteristics of the capacitor element after impregnation, and no etching of aluminum oxide by electrolyte.

The main components of the electrolyte are ion-forming substances (ionogens) - organic and inorganic acids and their salts, but they are rarely used directly in the form as they are, and, as a rule, require dissolution in a suitable solvent for electrolytic dissociation to form ions and an electrolyte with the desired viscosity was obtained.

Of the organic acids, monocarboxylic (nonanoic, oleic, stearic) and dicarboxylic acids (succinic, adipic, azelaic, sebacic, dodecandicarboxylic, tridecandicarboxylic) can be used, and from inorganic acids, orthophosphoric, boric acids or their enhancing stresses and their ammonium stresses electrolyte ability.

For capacitors with higher nominal voltages, lactones and amide-containing solvents can be used as solvents. Lactone-based electrolytes allow capacitors to achieve high reliability and a long service life, however, the lower limit of the operating temperature of capacitors with such electrolytes is limited, as a rule, to minus 55 ° С. Electrolytes based on amide-containing solvents allow the capacitor to reach the lower limit of the operating temperature of minus 60 ° C and even lower, but these electrolytes are not able to provide a long life of the capacitor, since, firstly, they are very volatile, and secondly, they react with aluminum oxide on the anode, destroying it, which leads to an increase in the leakage current in the capacitor and to reduce its service life. However, with a significant decrease in the content of amide-containing solvents or replacing them with other solvents that are less volatile and less aggressive with respect to alumina, the low-temperature characteristics of the electrolyte, and therefore the capacitor, deteriorate and the conductivity of the electrolyte decreases. The use of cosolvents allows for a lower working temperature. The use of a mixed solvent in the electrolyte containing lactone as the main solvent due to its stability and low toxicity and an amide-containing solvent as a co-solvent allows one to increase the electrolyte conductivity in НУ, as well as at low temperatures, up to minus 60 ° С, and at elevated temperatures and at This will provide high reliability and a long service life of both the electrolyte and the capacitor.

An increase in the service life is facilitated by the introduction of additives into the electrolyte, for example, an aromatic nitro compound as a cathode depolarizer, which prevents the destruction of alumina and enhances the absorption of gaseous hydrogen generated during electrolysis, which occurs during operation of the capacitor, especially at elevated temperatures.

The specific conductivity of the electrolyte depends on the residual water content in the prepared electrolyte, including that formed during the chemical interaction of its components, and therefore on the composition of the electrolyte, as well as on the final heating temperature of the electrolyte, which corresponds to the final moment of its preparation and is the highest temperature, to which the electrolyte is heated, and from the time of its preparation. To increase the conductivity, deionized water can also be added to the electrolyte.

The voltage of the anode breakdown depends on the final temperature of the heating of the electrolyte, while dicarboxylic acids increase its value.

As a rule, the electrolyte should have a logarithm of the concentration of hydrogen ions (pH) of about 7 so that unwanted processes do not appear that impair the performance and life of the capacitor, for example, the dissolution of aluminum and aluminum oxide in the electrolyte or hydration of aluminum oxide. The pH value depends both on the composition of the electrolyte and on the temperature of its preparation. To finally bring the pH to the desired value, amine is added.

Viscosity characterizes the consistency of the electrolyte and depends on the content of water and volatile substances in it, as well as on the temperature and time of preparation of the electrolyte.

Ultimately, both the composition and the technology of its preparation affect the parameters of the electrolyte, and the electrical characteristics of the capacitor and its service life largely depend on the parameters of the electrolyte used in it.

Known electrolyte described in patent US 6285543, class. H01G 9/02, publ. 09/04/2001, which consists of an organic solvent mixed with water - proton, for example ethylene glycol, non-proton, for example gluconic lactone, or a mixture thereof - in the ratio (80-20): (20-80) wt.%, Ionogen, represented by carboxylic acid for example benzoic or its salt or inorganic acid, for example boric or its salt, and additives in the form of a single nitro compound or a combination of two or more nitro compounds, such as nitrophenol, nitroacetophenone, nitrobenzoic acid, dinitrobenzoic acid, nitroanisole; works well at voltages of 160-500 V; has low impedance, good durability, very stable characteristics at low temperatures up to minus 40 ° C; able to absorb gaseous hydrogen generated during operation, even at elevated temperatures of 105 ° C and a high water content in the mixed solvent.

However, this electrolyte cannot work at a temperature of minus 60 ° C and has increased toxicity when a combination of several nitro compounds is included in its composition.

Also known is the electrolyte described in US Pat. No. 6,744,619, cl. H01G 9/42, publ. 06/01/2004, which contains ethylene glycol as the main solvent; polar organic cosolvent, for example alkanol; a co-solvent with a high dielectric constant, for example acetonitrile; aliphatic dicarboxylic acid, for example sebacic acid; monocarboxylic acid, for example dodecanoic acid; an amine, for example ethyldiisopropylamine, and to which, if necessary, small amounts of boric acid, hypophosphorous acid, a nitroaromatic compound, for example nitroanisole, as well as ammonium hydroxide, deionized water can be added. The electrolyte provides reduced gas generation and good operation of the capacitor for rated voltages up to 440 V at elevated temperatures.

This electrolyte is not suitable for operation at low temperatures, especially at a temperature of minus 60 ° C, and its performance is not guaranteed at a nominal voltage of 450 V.

Also known is an electrolyte for an aluminum electrolytic capacitor described in patent EP 0396192, cl. H01G 9/02, publ. 11/07/1990, where the electrolyte contains boric acid, an amine and a mixture of organic solvents, in which one of them, for example, butyrolactone, dimethylacetamide, dimethylformamide or a combination of dimethylacetamide with dimethylformamide, makes up most of the mixture, and the other, for example polyethylene glycol, its smaller part. The electrolyte is able to operate at voltages above 200 V in the temperature range from minus 40 to 105 ° C and absorb the gaseous hydrogen formed during operation, so that there is little or no gas left.

However, this electrolyte does not work at voltages of 400-450 V and at low temperatures up to minus 60 ° C.

There is a known method of preparing an electrolyte described in the aforementioned US Pat. No. 6,744,619, where first ethylene glycol and cosolvents having a high boiling point are heated to 60-65 ° C and dicarboxylic, monocarboxylic and boric acids are added to them, then the solution is heated to 120-130 ° C and kept it at this temperature for 1 h, after which, for the introduction of the cathode depolarizer, the solution is cooled to 90 ° C (in the case of the use of a non-volatile substance) or to 50 ° C (in the case of the use of a volatile substance such as nitroanisole) and mixed him The appropriate cathode depolarizer, then the solution was cooled to 30 ° C, water was added, hypophosphorous acid and ammonium hydroxide and stirred, followed by neutralization of the acid medium for some added an amine, e.g., anhydrous ammonia, and the electrolyte is adjusted to pH 6-10.

In this method, the electrolyte preparation process is not optimized for such parameters as the mixing speed and the temperature setting rate, and this leads to the entry of the ingredients into undesirable redox reactions or, conversely, to incomplete reaction between themselves, which degrades the low-temperature characteristics of the electrolyte and reduces it conductivity.

Known aluminum electrolytic capacitor described in the above patent US 6285543, which operates at voltages of 160-500 V in the range of operating temperatures from minus 40 to 105 ° C, where the electrolyte consists, for example, mixed with water in the ratio (80-20) : (20-80) wt.% Ethylene glycol or gluconic lactone, or mixtures thereof; a carboxylic acid, for example benzoic, or a salt thereof; inorganic acid, for example boric, or its salt; additives in the form of a single nitro compound or a combination of two or more nitro compounds, such as nitrophenol, nitroacetophenone, nitrobenzoic acid, dinitrobenzoic acid, nitroanisole. The capacitor has a low impedance, good durability, very stable characteristics at low temperatures up to minus 40 ° C and good absorption of hydrogen gas generated during operation, even at an elevated temperature of 105 ° C and a high water content in the mixed solvent.

However, this capacitor cannot operate at a temperature of minus 60 ° С, and during production it has increased toxicity when a combination of several nitro compounds is used as a cathode depolarizer in it.

Also known is an aluminum electrolytic capacitor described in the aforementioned US Pat. No. 6,744,619, wherein ethylene glycol is used as the main solvent in the electrolyte; polar organic cosolvent, for example alkanol; a co-solvent with a high dielectric constant, for example acetonitrile; aliphatic dicarboxylic acid, for example sebacic; monocarboxylic acid, for example dodecanoic; an amine, for example ethyldiisopropylamine, and, if necessary, small amounts of boric acid, hypophosphorous acid, ammonium hydroxide, deionized water and a nitroaromatic compound, for example nitroanisole can be added. The capacitor works well for rated voltages up to 440 V at elevated temperatures and under these conditions has reduced gas generation.

This capacitor is not able to operate at low temperatures, especially at a temperature of minus 60 ° C, and its operability is not guaranteed at a nominal voltage of 450 V.

The tasks of the inventions form the complex task of creating an electrolyte of such a composition and such a cooking method to obtain an aluminum electrolytic capacitor with this electrolyte for nominal voltages of 400-450 V, which works well at temperatures from minus 60 to 105 ° C, especially at low temperatures.

This complex problem is solved by research and development of an electrolyte, a method for its preparation and a capacitor with such an electrolyte, allowing to obtain such technical results as:

- good temperature stability of the parameters of the electrolyte, especially conductivity, and the electrical characteristics of the capacitor in the entire range of operating temperatures, especially at low temperatures;

- good forming ability of the electrolyte, which guarantees stable operation of the capacitor at specified nominal voltages in the specified range of operating temperatures, especially at low temperatures;

- reduced gas formation of the electrolyte and, accordingly, reduced hydrogen evolution at the cathode of the capacitor;

- high breakdown voltage of the electrolyte and, accordingly, the capacitor;

- reduced toxicity of the electrolyte;

- high corrosion resistance of the capacitor;

- low capacitor impedance.

An electrolyte is proposed, which includes the following components with the following qualities:

- a mixture of organic solvents, in which the main solvent is lactone due to its stability and low toxicity, for example, γ-butyrolactone, γ-valerolactone, δ-valerolactone, the former being preferred; cosolvents — a combination of two amide-containing solvents, for example dimethylformamide, methylformamide, dimethylacetamide, diethylformamide, the former being preferred and, for example, N-methylpyrrolidone, 2-pyrrolidone, the former being preferred; the mixture of γ-butyrolactone with a combination of dimethylformamide and N-methylpyrrolidone provides better acid solubility and better low-temperature parameters of the high-voltage electrolyte than with each of the amide-containing solvents separately. To enhance the effect of increasing the solubility and dissociation of acids, reducing electrochemical corrosion, and enhancing gas absorption, polyhydric alcohols - ethylene glycol and / or a second polyhydric alcohol selected from the series polyethylene glycol, glycerol, 2-methoxyethanol, diethylene glycol, its monomethyl methyl and monomethyl methyl can be added as additional cosolvents esters, triethylene glycol, the former being preferred;

- dicarboxylic acid (or its ammonium salt), which, as the main ionogen, provides good electrolyte conductivity, for example, sebacic, succinic, adipic, azelaic, dodecandicarboxylic, tridecandicarboxylic acid, the former being preferable, since it provides the best ratio for rated voltages of 400-450 V breakdown voltage and conductivity compared with other acids at the same concentration, while the acid content should not exceed the concentration of the saturated solution;

- boric acid, which helps to increase the sparking voltage and improve the forming ability;

- an aliphatic amine, better tertiary due to its lower volatility and greater stability at elevated temperature, which acts as an organic base that optimizes pH by neutralizing the acidic environment of the electrolyte, and in part as an ionogen, which further improves the conductivity of the electrolyte, for example ethyldiisopropylamine, triethylamine, triethanolamine tributylamine, the former being preferred, since due to the branched chain substituents it is possible to increase the breakdown voltage without reducing the specific conductivity and;

- aromatic nitro compound, which, if necessary, can be added to the electrolyte as a cathode depolarizer to counteract the process of gas generation and hydrogen evolution at the cathode of the capacitor, for example nitroanisole, nitroacetophenone, the former being preferred;

- a polysaccharide, which, if necessary, can be added to the electrolyte to prevent hydration of the foil in the capacitor, for example D-mannitol, D-erythritol, xylitol, the first being preferred;

- deionized water, which, if necessary, can be added to the electrolyte to increase conductivity.

The electrolyte composition is optimized for the components and their quantitative ratios and is presented in table 1.

Table 1
Electrolyte composition No. p / p Component Name The content of the component, wt.% one γ-butyrolactone 30-70 2 N-methylpyrrolidone 10-40 3 Dimethylformamide 10-40 four Sebacic acid 3-16 5 Ethyldiisopropylamine 1-10 6 Boric acid 0.5-10 7 D-mannitol 0.1-5 8 Ethylene glycol 0-7 9 Polyethylene glycol 0-6 10 Nitroanisole 0-5 eleven Deionized water 0-3.5

table 2
Electrolyte parameters No. p / p Parameter Name Parameter value one Specific conductivity, mS / cm: - at a temperature of 20 ° C not less than 0.71 - at a temperature of minus 60 ° C no less than 0,0285 2 pH 6-8 3 Viscosity, s no more than 10 four Spark voltage, V not less than 530 5 Forming ability: - molding voltage, V not less than 510 - time to achieve molding stress, min no more than 6 - residual current, mA no more than 8.5

The electrolyte parameters have also been optimized for given nominal voltages of 400-450 V and operating temperatures from minus 60 to 105 ° C (see Table 2), which depend both on the composition of the electrolyte and on the modes of its preparation when mixing and chemical the interaction of the electrolyte components with each other, as well as the physical effect on the components of the regime factors.

The optimization of the electrolyte composition and its parameters was carried out according to research results, in particular, the dependence of the electrolyte parameters on the final temperature of its heating. The breakdown voltage, molding voltage, resistance both in the NU and at low temperatures are especially dependent on the final temperature of the heating of the electrolyte. In this case, the final heating temperature should provide the optimal ratio between the specific conductivities of the electrolyte under the indicated temperature conditions and the breakdown and molding voltages (see graphs of Figs. 1-3). The graphs show that the most acceptable value of the final temperature of the heating of the electrolyte is 100 ± 5 ° C.

A method for preparing an electrolyte is proposed, which consists in first that the solvents are mixed with each other and heated to improve the solubility of the components to a temperature of 40 ° C, not higher, with constant stirring, then the remaining components are introduced (see Table 1), except ethyldiisopropylamine, and they are mixed until complete dissolution, after which ethyldiisopropylamine is added and, with constant stirring, the mixture is heated to a final temperature of heating the electrolyte, which is 100 ± 5 ° C, then the electrolyte is forced cooled to about 30 ° C, not higher, for about 15 minutes. At the same time, they provide a uniform temperature set at a speed of 2-5 ° C per minute, and preferably 4 ° C per minute, and mixing at a stirrer speed of 50-80 rpm, since the mixing speed less than that indicated can lead to incomplete dissolution of the components, and more than that, to an undesirable saturation of the electrolyte with oxygen and, as a consequence, to the entry of components into undesirable redox reactions — all these effects lead to non-optimal electrolyte parameters.

The optimized composition of the electrolyte and the method of its preparation under optimal technological conditions give a synergistic effect with respect to the parameters of the electrolyte and the characteristics of the capacitor, which makes it possible to best implement this electrolyte in capacitors with increased nominal voltages, in this case 400-450 V, which can work well in the temperature range from minus 60 to 105 ° C, especially at low temperatures.

The following factors lead to a synergistic effect: firstly, optimization of the content of components in the electrolyte composition, which can significantly reduce the freezing temperature of the electrolyte while maintaining the achieved solubility of ionogens and, therefore, a good degree of dissociation, and this increases the conductivity and temperature stability of the electrolyte; secondly, optimization of the electrolyte preparation method: introduction of soluble components into a mixture of organic solvents, heated to the optimum temperature, which again improves the solubility of the components and increases the conductivity of the electrolyte; selection of optimal mixer speeds for mixing the components and setting the maximum temperature for heating the electrolyte; determining the optimal value of the final temperature of heating of the electrolyte - all this improves all the parameters of the electrolyte, especially conductivity, especially at low temperatures.

An aluminum electrolytic capacitor for rated voltages of 400-450 V and operating temperatures from minus 60 to 105 ° C is a capacitor element obtained by winding from cathode and anode aluminum foil with a capacitor paper gasket, impregnated with electrolyte and placed in an aluminum case, an outlet in which it is closed by a lid with a sealing rubber element, the electrolyte having a composition in accordance with the claimed electrolyte and prepared by a method in accordance with the claimed method obom preparation of this electrolyte. The design of the case and cap of the capacitor can have axial or radial versions of the terminals: a capacitor with radial terminals has external, anode and cathode terminals on the cover, and a capacitor with axial terminals has a body with a pre-welded external cathode wire terminal, and the cover is made as rubberized terminal with a welded external anode wire terminal.

In the proposed invention, the complex task is solved and the above technical results are achieved due to the following factors.

Good temperature stability of the electrolyte parameters, especially conductivity, over the entire range of operating temperatures, especially at low temperatures - and the conductivity from NU to minus 60 ° С decreases slightly (see Table 2) - is achieved due to the synergistic effect described above.

A sufficiently good forming ability of the electrolyte for a given rated voltage of 400-450 V (see Table 2) is achieved by introducing boric acid into the electrolyte, the presence of components contributing to the improvement of the forming ability of components, such as polyhydric alcohols, deionized water, and optimization of the electrolyte composition and the final temperature of its heating (see table 1).

Reduced gas formation of the electrolyte and, accordingly, hydrogen evolution at the cathode of the capacitor is ensured by introducing a small amount of aromatic nitro compound into the electrolyte, preferably nitroanisole, as a cathode depolarizer (see Table 1), which is associated with the presence of a lactone, especially γ-butyrolactone, and polyhydric alcohol, especially ethylene glycol and / or polyethylene glycol, which behave partly as cathode depolarizers.

The increased breakdown voltage of the electrolyte and, accordingly, the capacitor, taking into account the specified nominal voltages of 400-450 V, is achieved by increasing the sparking voltage of the electrolyte, which is facilitated by the presence of boric acid, a tertiary aliphatic amine in the electrolyte, ethyldiisopropylamine is preferable here, and to some extent polyhydric alcohol, ethylene glycol and / or polyethylene glycol are preferred here (see table 1), which further increases the specific conductivity of the electrolyte.

The reduced toxicity of the electrolyte is ensured by the fact that non-toxic or low-toxic components occupy a fraction of 95-100 wt.% In its composition, and the presence of toxic compounds is limited to their use only as additives - in small quantities and only if necessary (see Table 1).

Good temperature stability of the electrical characteristics of the capacitor over the entire range of operating temperatures (see table 3) is determined by the good temperature stability of the electrolyte parameters (see table 2).

The high corrosion resistance of the capacitor is ensured by the optimized component composition of the electrolyte, which exhibits sufficient inertness with respect to alumina, aluminum itself and the material of other elements of the capacitor by reducing the reactivity of amide-containing cosolvents, in particular dimethylformamide and N-methylpyrrolidone, necessary to achieve good low-temperature characteristics of the electrolyte, especially at a temperature of minus 60 ° С, by either reducing their content or applying supplement nyh cosolvents - polyhydric alcohols, particularly ethylene glycol and / or polyethylene glycol.

The proposed capacitor in the entire range of operating temperatures is characterized by good electrical characteristics, in particular low impedance, especially at low temperature, high anode breakdown voltage relative to rated voltages, reduced hydrogen evolution at the cathode and high corrosion resistance due to the synergistic effect of optimizing the composition and preparation method described above electrolyte.

Figure 1 graphically represents the dependence of the breakdown voltage and the molding voltage of the electrolyte on the final temperature of the heating of the electrolyte.

Figure 2 graphically represents the dependence of the specific conductivity of the electrolyte, measured at a temperature of 20 ° C (NU), on the final temperature of the heating of the electrolyte.

Figure 3 graphically represents the dependence of the specific conductivity of the electrolyte, measured at a temperature of minus 60 ° C (the lower limit of the range of operating temperatures), on the final temperature of the heating of the electrolyte.

The proposed inventions were implemented at Elekond OJSC, Sarapul, where K50-76 aluminum electrolytic capacitor is produced in serial production using the proposed electrolyte prepared by the proposed method.

The electrolyte preparation technology, the composition of which is described above and indicated in Table 1, includes the following technological steps:

1. Loading solvents: γ-butyrolactone, N-methylpyrrolidone, dimethylformamide and, if necessary, ethylene glycol and / or polyethylene glycol, into the reactor of the installation at ambient temperature and the inclusion of a heating device and stirrer.

2. Heating of solvents to a temperature of no higher than 40 ° C with constant stirring and uniform temperature set.

The speed of the mixer is set to 50-80 rpm, and the speed of the temperature set is 2-5 ° C per minute.

3. Download the remaining components of the electrolyte listed in table 1, except ethyldiisopropylamine, and their constant stirring at the indicated temperature until complete dissolution.

4. Loading ethyldiisopropylamine with subsequent heating of the mixture to a final temperature of heating the electrolyte of 100 ± 5 ° C with constant stirring and uniform temperature selection at the speeds specified in paragraph 2, and then turning off the heating device and mixer.

5. Forced cooling of the electrolyte to a temperature of no higher than 30 ° C for about 15 minutes and the discharge of the finished electrolyte into a container for storing electrolyte.

The heating time to a temperature of 40 ° C is not an essential technological parameter, since here the difference between the temperatures of the start and end of heating is small and the set temperature is reached quite quickly, which depends on the power of the heating device.

A stirrer speed less than the above value can lead to incomplete dissolution of the components with stirring, and too high a speed can lead to oxygen saturation of the electrolyte and, as a consequence, to the components entering into undesirable redox reactions.

The rate of temperature rise below the value indicated above leads to the partial evaporation of more volatile components, and the high speed leads to incomplete reaction of the components with each other. As a result, the conductivity decreases and the low-temperature characteristics of the electrolyte, and therefore the capacitor, deteriorate.

The following are examples of the implementation of acceptable electrolyte options.

Example 1. The electrolyte contains: 31.1 wt.% Γ-butyrolactone, 14.6 wt.% N-methylpyrrolidone, 29.3 wt.% Dimethylformamide, 1.1 wt.% Ethylene glycol, 8.2 wt.% Sebacic acid , 7.7 wt.% Ethyldiisopropylamine, 6.4 wt.% Boric acid, 0.2 wt.% D-mannitol, 1.4 wt.% Deionized water.

The electrolyte was prepared according to the above technology, where the stirring speed was set to 50 rpm and the temperature set speed

2 ° C per minute; the final electrolyte heating temperature of 95 ° C was reached in 27 minutes (time is indicated for reference); forced cooling of the electrolyte to 30 ° C is achieved in 15 minutes.

Electrolyte parameters: specific conductivity: 1.02 mS / cm at 20 ° C; 0.0417 mS / cm at minus 60 ° C; pH 7; viscosity 10 s; sparking voltage 530 V; forming ability: molding voltage of 510 V, time to reach it 3.2 minutes, residual current 6.0 mA.

Example 2. The electrolyte contains: 36.2 wt.% Γ-butyrolactone, 28.6 wt.% N-methylpyrrolidone, 10.2 wt.% Dimethylformamide, 1.9 wt.% Ethylene glycol, 0.3 wt.% Polyethylene glycol, 9.1 wt.% Sebacic acid, 5.6 wt.% Boric acid, 7.7 wt.% Ethyldiisopropylamine, 0.3 wt.% Nitroanisole, 0.1 wt.% D-mannitol.

The electrolyte was prepared according to the above technology, where the stirring speed was set to 80 rpm, and the temperature set speed was 5 ° C per minute; the final electrolyte heating temperature of 105 ° C was reached in 13 minutes (time is indicated for reference); forced cooling of the electrolyte to 30 ° C was achieved in 13 minutes.

Electrolyte parameters: specific conductivity: 0.79 mS / cm at 20 ° C; 0.0345 mS / cm at minus 60 ° C; pH 7; viscosity 10 s; sparking voltage 560 V; forming ability: molding voltage 520 V, the time it takes to reach 5.4 minutes, residual current 4.0 mA.

The proposed electrolyte allows you to implement a capacitor with good, stable reliability and electrical characteristics, in particular with low impedance.

Table 3 shows the electrical characteristics of the K50-76 aluminum electrolytic capacitor, in particular, a rating of 450 V × 10 μF, made with a working electrolyte according to the present invention, obtained during acceptance and climatic tests, as well as failure-free tests.

Table 3
Capacitor Electrical Specifications No. p / p Name of characteristic, unit of measure Characteristic value for capacitor K50-76, nominal 450 V × 10 μF one Mechanical damage to the capacitor,%, due to failure: - corrosion 0 - increased gas evolution, 0 - anode breakdown 0 2 Capacitance, microfarad 10 ± 20% 3 Dielectric loss tangent,%, at temperature: - 25 ° С (NU), 10 and less - minus 60 ° C, 150 and less four Impedance, Ohm, at a temperature of 25 ° С (NU) at a frequency of 100 kHz 9.9 and less 5 The impedance ratio at minus 60 ° C and at 25 ° C (NU) at a frequency of 50 Hz 6 and less 6 The relative change in capacity,%, at temperature: - minus 60 ° C, minus 50 or more - 105 ° C ± 20 7 Leakage current, μA, at temperature: - 25 ° С (NU), 135 and less - 105 ° C 405 and less 8 MTBF, h, at increased operating temperature / voltage: - 60 ° С / Un 5000 and more - 105 ° C / 0.5Unom 2000 and more

Positive test results confirm the operability of the working electrolyte and capacitor of the present invention for operating voltages of 400-450 V and operating temperatures from minus 60 to 105 ° C.

Claims (10)

1. The working electrolyte for the capacitor for rated voltages of 400-450 V and operating temperatures from minus 60 to 105 ° C, which includes a mixture of organic solvents, dicarboxylic acid or its ammonium salt, boric acid, polysaccharide, tertiary aliphatic amine at pH of the electrolyte 6-8, characterized in that in the electrolyte lactone as the main solvent occupies 30-70 wt.%, Two amide-containing cosolvents - 10-40 wt.% Each, dicarboxylic acid or its ammonium salt - 3-16 wt.%, Boric acid - 0.5-10 wt.%, Polysaccharide - 0.1-5 wt.%, Tertiary aliphatic amine - 1-10 wt.%; the electrolyte additionally contains 0-7 wt.% ethylene glycol and / or 0-6 wt.% the second polyhydric alcohol as additional co-solvents, 0-5 wt.% aromatic nitro compounds and 0-3.5 wt.% deionized water. 2. The working electrolyte according to claim 1, characterized in that the lactone is selected from the series: γ-butyrolactone, γ-valerolactone, δ-valerolactone, the former being preferred. 3. The working electrolyte according to claim 1, characterized in that one amide-containing co-solvent is selected from the series: dimethylformamide, methylformamide, diethylformamide, dimethylacetamide, the first being preferred, and the other amide-containing co-solvent from the series: N-methylpyrrolidone, 2-pyrrolidone, the first preferred. 4. The working electrolyte according to claim 1, characterized in that the dicarboxylic acid is selected from the series: sebacic acid, succinic acid, adipic acid, azelaic acid, dodecandicarboxylic acid, tridecandicarboxylic acid, the first being preferred. 5. The working electrolyte according to claim 1, characterized in that the polysaccharide is selected from the series: D-mannitol, D-erythritol, xylitol, the first being preferred. 6. The working electrolyte according to claim 1, characterized in that the tertiary aliphatic amine is selected from the series: ethyldiisopropylamine, triethylamine, triethanolamine, tributylamine, the first being preferred. 7. The working electrolyte according to claim 1, characterized in that the second polyhydric alcohol as an additional co-solvent is selected from the series: polyethylene glycol, glycerin, 2-methoxyethanol, diethylene glycol, diethylene glycol monomethyl and monoethyl ether, triethylene glycol, the first being preferred. 8. The working electrolyte according to claim 1, characterized in that the aromatic nitro compound is selected from the series: nitroanisole, nitroacetophenone, the first being preferred. 9. The method of preparing the working electrolyte according to claim 1 for a capacitor for rated voltages of 400-450 V and operating temperatures from minus 60 to 105 ° C, which consists in mixing and heating the solvents with constant stirring, the introduction of the remaining electrolyte components, except for the tertiary aliphatic amine and adding after complete dissolution of the components of the tertiary aliphatic amine with heating the mixture to a final temperature of heating the electrolyte with constant stirring and subsequent forced cooling, in that the heating temperature of the mixed solvent is 40 ° C, not higher final electrolyte heating temperature - 100 ± 5 ° C, cooling the electrolyte temperature - not higher. 10. Aluminum electrolytic capacitor for rated voltages of 400-450 V and operating temperatures from minus 60 to 105 ° C, which is a capacitor element obtained by winding from cathode and anode aluminum foil with a capacitor paper gasket, impregnated with a working electrolyte and placed in aluminum case, the outlet in which is closed by a lid with a sealing rubber element, characterized in that the working electrolyte has the composition according to claim 1 and is prepared by the method according to claim 9.

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