TW201419334A - Electrolyte for aluminum electrolytic capacitor and aluminum electrolytic capacitor - Google Patents

Abstract

An excellent thermal stability Electrolyte for aluminum electrolytic capacitor and aluminum electrolytic capacitor including said electrolyte, the electrolyte includes the following components: organic solvent, 2-decoyl-adipic acid, or combination of 2-decoyl-adipic acid and its ammonium salt. The electrolyte has better thermal stability.

Description

Aluminum electrolytic capacitor electrolyte and aluminum electrolytic capacitor

The invention relates to the field of electrochemistry, in particular to an electrolytic solution of an aluminum electrolytic capacitor and an aluminum electrolytic capacitor.

A capacitor is an energy storage component used in circuits for tuning, filtering, coupling, bypassing, energy conversion, and delay. Aluminum electrolytic capacitors are characterized by large capacity, but large leakage, large error, and poor stability. They are often used for AC bypass and filtering, and are also used for signal coupling when the requirements are not high. The typical structure of an aluminum electrolytic capacitor is an aluminum cylinder as a negative electrode, which is filled with a liquid electrolyte, and a bent aluminum strip is inserted as a positive electrode. The core is made up of an anode aluminum foil, a liner paper impregnated with an electrolyte, a cathode aluminum foil, a natural oxide film, etc., and the core is impregnated with an electrolyte and sealed with an aluminum shell and a rubber cover to form an electrolytic capacitor. . Among them, the electrolytic capacitor of aluminum electrolytic capacitor has experienced the following development process:

(1) Boric acid + ethylene glycol system: This system is the electrolyte used in the early stage of aluminum electrolytic capacitors. When a large amount of condensed water is formed between the ethylene glycol and the boric acid in the electrolytic solution due to the esterification reaction, the moisture content in the electrolyte system is increased, and as a result, the electrolyte is used at a use temperature exceeding 100 ° C. The water in the electrolyte will become water vapor and evaporate. As the internal pressure of the electrolytic capacitor increases, so-called damage problems are inevitable. The system cannot be used in a high temperature environment and has been basically eliminated.

(2) Linear carboxylate + ethylene glycol system: an electrolyte containing a linear saturated dicarboxylic acid such as sebacic acid, sebacic acid or dodecanedioic acid or a salt thereof as an electrolyte, which is currently domestic Widely used system, but the linear carboxylate has crystal precipitation at low temperature, which affects the low temperature performance of the capacitor, and the linear conductivity of the linear carboxylate system changes greatly, and the capacitor loss changes greatly. These problems are restricted. Further improvement in capacitor performance.

(3) Branched carboxylate + ethylene glycol system: Foreign manufacturers often use branched carboxylate as the main electrolyte. Relative to linear carboxylic acids, the introduction of side chain groups in branched carboxylic acids enhances their ability to inhibit esterification under high temperature conditions, thereby increasing high temperature stability: and due to side chains The steric hindrance of the upper group and the polarization of the alkoxy group increase the solubility in ethylene glycol, thereby improving its low temperature performance. The solubility and thermal stability of the branched carboxylate are better than those of the straight chain. Chain carboxylates can produce capacitor products with superior performance.

Chinese Patent Application No. 201110100364.3 discloses CN102254690 A, which discloses a high-pressure working electrolyte for driving, which uses ethylene glycol as a solvent to 2,2,4-trimethyladipate and 2,4,4-trimethyl. A mixed acid of adipic acid and a salt thereof are main electrolytes, and various additives are added to form an electrolyte. Using this electrolyte, the flash voltage is 380-410V, high temperature resistance, high longevity, and 125°C life test for 2000h or more. However, the electrolyte flash voltage is not high.

An object of the present invention is to provide an aluminum electrolytic capacitor electrolyte which has a high flash voltage and is excellent in thermal stability. Meanwhile, the present invention also provides an aluminum electrolytic capacitor prepared using the above electrolyte.

An aluminum electrolytic capacitor electrolyte according to the present invention is characterized in that it comprises the following components: an organic solvent; a combination of ammonium 2-hexyl adipate or 2-hexyl adipic acid and an ammonium salt thereof; The total content in the electrolyte is converted into 2-hexyl adipate to be 1 to 30% of the total mass of the electrolytic solution of the aluminum electrolytic capacitor; if the addition amount is less than 1% of the total mass of the electrolytic solution of the aluminum electrolytic capacitor, The effect of improving the flash voltage and thermal stability; if the concentration exceeds 30% of the total mass of the electrolytic solution of the aluminum electrolytic capacitor, the characteristics of the electrolytic capacitor at a low temperature are degraded.

In the electrolyte solution of the present invention, the ammonium salt of 2-hexyl adipate may be contained, and the ammonium salt of 2-hexyl adipate and its ammonium salt may be contained at the same time, which is uniform and convenient for different formulations, and the content ratio of each component is In the invention, the content of ammonium 2-hexyl adipate is converted into 2-hexyl adipic acid in an amount equivalent to the substance to calculate the mass percentage.

The electrolyte may contain one or a combination of the following components: component a: an ammonium salt of a dicarboxylic acid of 8 to 11 carbon atoms, or a combination of the carboxylic acid and its ammonium salt, component b: 4-7 carbons An ammonium salt of an atomic monocarboxylic acid, or a combination of the carboxylic acid and its ammonium salt, component c: an ammonium salt of boric acid, or a combination of boric acid and an ammonium salt thereof. According to the same content measurement method, the total content of the above components a, b, c or a combination thereof is 1 to 5 of the total mass of the electrolyte of the aluminum electrolytic capacitor according to the content of the carboxylic acid or boric acid of the corresponding substance. %.

As a preferred embodiment of the present invention, the content of the 2-hexyl adipic acid or the ammonium salt thereof is converted into 2-hexyl adipate to be 2.5 to 10% of the total mass of the electrolytic solution of the aluminum electrolytic capacitor.

As a preferred embodiment of the present invention, the aluminum electrolytic capacitor electrolyte further contains a hydrogen absorbing agent.

As a more preferred embodiment of the present invention, the hydrogen absorbing agent is selected from one or more of p-nitrobenzoic acid, p-nitrobenzyl alcohol, m-nitroethyl benzene, and o-nitroanisole. Since the nitro group in these compounds has a reducing property, it can function to absorb hydrogen.

Further, the content of the hydrogen absorbing agent is 0.1 to 5% of the total mass of the electrolytic solution of the aluminum electrolytic capacitor. More preferably, it is 0.1 to 0.5%.

As a preferred embodiment of the present invention, the aluminum electrolytic capacitor electrolyte further contains an additive which suppresses leakage current and improves chemical conversion performance.

As a more preferred embodiment of the present invention, the additive for suppressing leakage current and improving chemical conversion property is selected from one or more of the following compounds: phosphoric acid, phosphorous acid, hypophosphorous acid, phosphoric acid monoester, and an ammonium salt of the foregoing compound (that is, The above acid or monoester compound may be contained in the electrolytic solution, or an ammonium salt of the above acid or monoester compound may be contained, or the above acid or monoester compound and an ammonium salt thereof may be contained together. When these compounds are adsorbed on the electrode foil, the reaction of the electrode foil with water can be suppressed without impairing the performance of the capacitor.

Further, the acid or monoester of the amount of the additive which suppresses the leakage current and the improvement of the chemical conversion property, which is equivalent to the amount of the corresponding substance, is 0.1 to 1.0% of the total mass of the electrolytic solution of the aluminum electrolytic capacitor.

As a preferred embodiment of the present invention, the linear dicarboxylic acid having 8 to 11 carbon atoms is one or more selected from the group consisting of ammonium suberate, ammonium sebacate, ammonium azelamate, and ammonium dodecanoate.

As a preferred embodiment of the present invention, the organic solvent is ethylene glycol or γ-butyrolactone.

Further, the present invention provides an aluminum electrolytic capacitor in which an electrolytic solution of an aluminum electrolytic capacitor according to the present invention is used.

The electrolyte provided by the invention has higher flashover voltage and better thermal stability, and the 2-hexyl adipate and its ammonium salt of the invention have better solubility in ethylene glycol. The aluminum electrolytic capacitor containing the electrolytic solution has the advantages of high withstand voltage and long life of the capacitor. 2-hexyl adipic acid and its ammonium salt, ammonium dicarboxylate salt containing 8-11 carbon atoms, or 4-7 carbon atoms The two monocarboxylic acid ammonium salts act synergistically to further enhance the capacitor characteristics of the electrolyte.

The details of the technical contents, the objects and effects achieved by the present invention will be described in detail below with reference to the embodiments.

Example 1

2-hexyl adipic acid and its ammonium salt (5%, ie 5% of the total weight of the electrolyte, the following examples are not described in the similar expression) are dissolved in ethylene glycol to form a solution, and then added in pairs Nitrobenzoic acid (0.2%) and hypophosphorous acid (0.2%) were sealed in a stainless steel bottle and thermostated at 105 °C.

Example 2

2-hexyl adipic acid and its ammonium salt (2.5%) were dissolved in ethylene glycol to form a solution, followed by ammonium sebacate (2.5%) and p-nitrobenzyl alcohol (0.1%) and hypophosphorous acid (0.1%). ), sealed in a stainless steel bottle and kept at a constant temperature of 105 ° C.

Example 3

2-hexyl adipic acid and its ammonium salt (4%) were dissolved in ethylene glycol to form a solution, followed by ammonium hydrogen ruthenate (1%) and m-nitroethyl benzene (0.5%) and hypophosphorous acid ( 0.1%), sealed in a stainless steel bottle and thermostated at 105 °C.

Example 4

2-hexyl adipate and its ammonium salt (3%) were dissolved in ethylene glycol to form a solution, followed by the addition of ammonium dodecanoate (2%) and o-nitroanisole (0.3%) and phosphoric acid monoester ( 0.1%), sealed in a stainless steel bottle and thermostated at 105 °C.

Example 5

2-hexyl adipic acid and its ammonium salt (3%) were dissolved in ethylene glycol to form a solution, followed by ammonium hexanoate (4%) and o-nitroanisole (0.3%) and hypophosphorous acid (0.1%). ), sealed in a stainless steel bottle and kept at a constant temperature of 105 ° C.

Example 6

2-hexyl adipic acid and its ammonium salt (3%) were dissolved in ethylene glycol to form a solution, followed by ammonium heptanoate (4%) and o-nitroanisole (0.3%) and phosphoric acid monoester (0.1%). ), sealed in stainless steel bottles Medium temperature at 105 °C.

Example 7

2-hexyl adipic acid and its ammonium salt (1%) were dissolved in ethylene glycol to form a solution, followed by ammonium octanoate (5%), p-nitrobenzyl alcohol (2%) and phosphoric acid (0.3%). Sealed in a stainless steel bottle and thermostated at 105 °C.

Example 8

2-hexyl adipic acid and its ammonium salt (30%) were dissolved in ethylene glycol to form a solution, followed by ammonium hydrogen ruthenate (1%), p-nitrobenzyl alcohol (5%) and ammonium phosphite (0.5 %), sealed in a stainless steel bottle and kept at a constant temperature of 105 °C.

Comparative example 1

Ammonium alginate (5%) was dissolved in ethylene glycol to form a solution, and then ammonium hypophosphite (0.2%) and p-nitrobenzoic acid (0.2%) were added, sealed in a stainless steel bottle, and thermostated at 105 °C.

Comparative example 2

Dissolve ammonium dodecanoate (5%) in ethylene glycol to form a solution, then add o-nitroanisole (0.3%) and monobutyl phosphate (0.1%) in a stainless steel bottle and incubate at 105 °C. .

Comparative example 3

Ammonium hexanoate (4%) was dissolved in ethylene glycol to form a solution, and then ammonium dodecanoate (4%) and o-nitroanisole (0.3%) and ammonium hypophosphite (0.1%) were sealed in stainless steel. Inside the bottle, the temperature was kept at 105 °C.

The above various examples and comparative examples were tested according to the usual technical means, and the results obtained are shown in Table 1 and Table 2: * The content of 2-hexyl adipic acid and its ammonium salt in the solute 1 in the table is calculated as the equivalent amount of 2-hexyl adipate by the amount of the substance and then the mass percentage in the electrolyte is calculated. The content of solute 2 and additive 2 is calculated in the same manner, and is not described here.

It can be seen from the above two tables that the aluminum electrolytic capacitor electrolyte using 2-hexyl adipic acid and its ammonium salt as the main solute in the present invention has an electrical conductivity and a conductivity retention ratio as compared with the existing electrolyte. A big boost.

The electrolytic solutions corresponding to the inventive examples 1 to 8 and the comparative examples 1 to 3 were respectively made into 400 V, 10 μF aluminum electrolytic capacitors, and after the 105 ° C high-temperature life test, the data shown in Table 3 was obtained.

It can be seen from the above table that the initial values of the capacitors produced in Examples 1 to 8 and Comparative Examples 1 to 3 are not much different. After the life test at 105 ° C and 2000 h, the DF values of the capacitors corresponding to the ratios 1 to 3 rise greatly. However, the capacitors corresponding to Examples 1 to 8 have better thermal stability.

The above is only the embodiment of the present invention, and thus does not limit the scope of the patent of the present invention. Any equivalent transformation made by using the contents of the specification of the present invention, or directly or indirectly applied to other related technical fields, is equally included in the present invention. The scope of patent protection of the invention.

Claims (11)

An aluminum electrolytic capacitor electrolyte characterized by comprising the following components: an organic solvent; a combination of 2-hexyl adipate ammonium or 2-hexyl adipic acid and an ammonium salt thereof, the 2-hexyl adipate ammonium or 2- The content of the combination of hexyl adipic acid and its ammonium salt is converted into 2-hexyl adipate to be 1 to 30% of the total mass of the electrolytic solution of the aluminum electrolytic capacitor. The aluminum electrolytic capacitor electrolyte according to claim 1, wherein the aluminum electrolytic capacitor electrolyte further comprises an ammonium salt corresponding to the following acid or a combination of the following acid and its ammonium salt: 8-11 A dicarboxylic acid having a carbon atom, or a monocarboxylic acid having 4 to 7 carbon atoms, or boric acid, wherein the total content of the above components is equivalent to 1 to 5% of the total mass of the electrolytic solution of the aluminum electrolytic capacitor. The aluminum electrolytic capacitor electrolyte according to claim 2, characterized in that the content of the combination of the ammonium 2-hexyl adipate or 2-hexyl adipate and its ammonium salt is converted into 2-hexylhexan The acid meter is 2.5~5% of the total mass of the electrolyte of the aluminum electrolytic capacitor. The aluminum electrolytic capacitor electrolyte according to claim 3, wherein the aluminum electrolytic capacitor electrolyte further contains a hydrogen absorbing agent. The aluminum electrolytic capacitor electrolyte according to claim 4, wherein the hydrogen absorbing agent is selected from the group consisting of p-nitrobenzoic acid, p-nitrobenzyl alcohol, m-nitroethyl benzene, o-nitrobenzene One or more of methyl ether, the content of the hydrogen-reducing agent being 0.1-5% of the total mass of the electrolytic solution of the aluminum electrolytic capacitor. The aluminum electrolytic capacitor electrolyte according to claim 5, wherein the hydrogen-removing agent is contained in an amount of 0.1 to 0.5% by mass based on the total mass of the electrolytic solution of the aluminum electrolytic capacitor. The aluminum electrolytic capacitor electrolyte according to claim 2, wherein the aluminum electrolytic capacitor electrolyte further contains an additive that suppresses leakage current and improves chemical conversion performance. An aluminum electrolytic capacitor electrolyte according to claim 7, wherein the additive for suppressing leakage current and improving chemical conversion property is selected from one or more of the following compounds: phosphoric acid, phosphorous acid, hypophosphorous acid, The phosphoric acid monoester or the ammonium salt of the foregoing compound, the content of the additive for suppressing leakage current and improving the chemical conversion property is equivalent to 0.1 to 0.5% of the total mass of the electrolytic solution of the aluminum electrolytic capacitor. The aluminum electrolytic capacitor electrolyte according to any one of claims 2-8, wherein the dicarboxylic acid having 8 to 11 carbon atoms is selected from the group consisting of ammonium suberate, ammonium sebacate, and sunflower. One or more of ammonium diphosphate and ammonium dodecanoate. The aluminum electrolytic capacitor electrolyte according to any one of claims 2 to 8, wherein the organic solvent is ethylene glycol or γ-butyrolactone. An aluminum electrolytic capacitor, characterized in that the electrolytic solution in the aluminum electrolytic capacitor is the aluminum electrolytic capacitor electrolyte according to any one of claims 1-10.