Electrolyte solute and preparation method thereof, electrolyte and aluminum electrolytic capacitor

Abstract

The invention relates to the field of electrolytes for aluminum electrolytic capacitors, in particular to an electrolyte solute and a preparation method thereof, an electrolyte and an aluminum electrolytic capacitor. The electrolyte solute comprises a branched chain polycarboxylic acid ammonium mixture, and the branched chain polycarboxylic acid ammonium mixture comprises 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, the additive is prepared from ammonium 5, 7 '-(octadecane-9, 10-diethyl) dioctyl pentadecanedioic acid, ammonium 8-(5-carboxypentyl)-7-octane hexadecanedioic acid, ammonium 10, 11-dioctyl eicosanedioic acid, ammonium 8-hydroxy-7-octane hexadecanedioic acid, ammonium (E)-7-hexadecane-8-octane enedioic acid and ammonium dodecanedioic acid. The electrolyte solute can obviously improve the conductivity and the sparking voltage of the electrolyte, and the high and low temperature resistance, the voltage resistance, the safety and stability performance and the like of the capacitor. Meanwhile, the preparation method of the solute is simple, high in product yield, low in cost, safe and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the field of electrolyte for aluminum electrolytic capacitors, and in particular to an electrolyte solute and a preparation method thereof, an electrolyte, and an aluminum electrolytic capacitor. Background Art

[0002] Aluminum electrolytic capacitors are widely used in filtering, bypassing, coupling, resonance, term transfer, energy storage, etc. due to their large capacitance per unit volume, small size, light weight and low price.

[0003] With the rapid development of new technologies (such as high-voltage inverters, electric vehicles, wind power generation and photovoltaic power generation, implantable medical devices, etc.), higher requirements are placed on aluminum electrolytic capacitors: (1) High voltage withstand capability (working voltage > 600V, i.e. ultra-high voltage aluminum electrolytic capacitors), able to withstand high surge voltage, and must work with a very small voltage drop; (2) Ability to withstand higher ripple current. High-frequency ripple current will cause the internal temperature of the capacitor to rise. If the core heats up severely, the electrolyte will dry up quickly, causing the capacitor to fail; (3) Satisfy the ability to work normally at the required maximum temperature and have high thermal stability; (4) Have a sufficiently long working life, and the capacitor can work normally for thousands or even tens of thousands of hours.

[0004] The electrolyte is the main component of the capacitor, and the characteristics of the electrolyte are the main factors that determine the performance of the capacitor. For example, the high temperature resistance of the electrolyte plays a major role in the high temperature life of the aluminum electrolytic capacitor, while the flash voltage of the electrolyte plays a major role in the withstand voltage performance of the aluminum electrolytic capacitor. The working electrolyte of the aluminum electrolytic capacitor is composed of a solvent, a solute, and an appropriate amount of additives. For high-voltage aluminum electrolytic capacitors, the solute system of the working electrolyte is extremely critical to its flash voltage.

[0005] With the development and progress of materials, after years of continuous improvement by researchers, the main solute system of high-voltage electrolyte has been continuously upgraded. Initially, boric acid or pentaboric acid was used as the main solute to prepare the electrolyte. The esterification of high-temperature boric acid and ethylene glycol will produce water. Excessive water content will cause corrosion of the aluminum electrode foil and produce hydrogen, which will increase the internal pressure of the electrolytic capacitor component, resulting in poor storage performance, service life and other electrical properties.

[0006] Later, straight-chain carboxylic acids or their ammonium salts were used as the main solutes to prepare electrolytes. This system can reduce the water content to a certain extent and has the advantage of low cost. However, as the carbon chain grows, the solubility of this type of main solute decreases, so the electrolyte resistivity is high, and it is difficult for electrolytic capacitors to achieve low losses. In addition, this type of solute has poor stability at high temperatures, making it difficult for capacitors to have high reliability and long life.

[0007] In order to obtain a high flash voltage, it is usually necessary to add a flash voltage enhancer, such as polyethylene glycol, polyvinyl alcohol, nano inorganic oxide particles, polyethylene oxide propylene oxide ether, etc. However, these materials themselves have no electrical conductivity and are only used as flash voltage enhancers. For aluminum electrolytic capacitors, since the liquid electrolyte is the actual cathode of the aluminum electrolytic capacitor, the conductive carriers of the actual cathode are no longer free electrons but ions, so this additive cannot enhance the ionic conductivity of the electrolyte.

[0008] A large amount of practice has proved that with the long-term use of the current high-voltage and ultra-high-voltage aluminum electrolytic capacitors, the components in the driving electrolyte slowly react chemically, the moisture content increases, the electrolyte conductivity decreases, and the loss angle factor change rate of the capacitor increases. In addition, the flash voltage of the electrolyte decreases, and when the aluminum electrolytic capacitor is under high temperature load, the electrode foil sparks and destroys the oxide film, which is also the main cause of anode corrosion. At the same time, the relevant performance parameters of the capacitor deteriorate sharply, causing the capacitor to fail, and the reliability cannot meet the needs of capacitor development. Therefore, it is urgent to provide an ultra-high voltage aluminum electrolytic capacitor electrolyte to overcome the above problems. Summary of the invention

[0009] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, the present invention provides an electrolyte solute and a preparation method thereof, an electrolyte, and an aluminum electrolytic capacitor. The electrolyte solute can significantly improve the conductivity and flash voltage of the electrolyte, as well as the high and low temperature resistance, pressure resistance, safety and stability of the capacitor. At the same time, the preparation method of the solute is simple, the product yield is high, the cost is low, and it is safe and environmentally friendly.

[0010] To this end, the first aspect of the present invention provides an electrolyte solute, including a branched polycarboxylic acid ammonium mixture, wherein the branched polycarboxylic acid ammonium mixture includes 7,7'-(octadecane-9,10-diethyl) dioctyl ammonium pentadecanedioate, 8-(5-carboxypentyl)-7-octane hexadecane dioate, 10,11-dioctyl ammonium eicosanedioate, 8-hydroxy-7-octane hexadecane dioate, (E)-7-hexadecane-8-octyl ammonium enedioate, and ammonium dodecanedioate.

[0011] The electrolyte solute provided by the present invention comprises a plurality of polybasic branched-chain carboxylic acid ammonium salts, and the steric hindrance of the groups on the side chains and the polarization effect of the alkoxy groups make the solubility and thermal stability of the branched-chain polybasic carboxylic acid salts superior to those of the linear carboxylic acid salts. At the same time, the branched-chain polybasic carboxylic acid salts can produce a synergistic effect with other ammonium carboxylate salts, and can significantly improve the conductivity and flash voltage of the electrolyte (up to 700V or more), and can be used for 650V ultra-high voltage aluminum electrolytic capacitors, and improve the high and low temperature resistance, voltage resistance, safety and stability of the capacitors.

[0012] According to an embodiment of the present invention, the mass proportion of 7,7'-(octadecane-9,10-diethyl) dioctylpentadecanedioic acid ammonium in the branched polycarboxylate ammonium mixture is 65% to 82%;

[0013] The mass proportion of the 8-(5-carboxypentyl)-7-octane hexadecane dicarboxylic acid ammonium is 8% to 20%;

[0014] The mass proportion of the 10,11-dioctyl ammonium eicosanedioate is 5% to 14%;

[0015] The mass proportion of the 8-hydroxy-7-octane hexadecane dioic acid ammonium is 3% to 10%;

[0016] The mass proportion of the (E)-7-hexadec-8-octylenedioic acid ammonium is 1% to 5%;

[0017] The mass proportion of the ammonium dodecanedioate is 0.5% to 2%.

[0018] The second aspect of the present invention provides a method for preparing the electrolyte solute according to the first aspect, comprising the following steps of preparing a branched polycarboxylic acid ammonium mixture:

[0019] Cyclohexanone can be used to obtain a straight-chain hexadecanoic acid ester with a free radical through a ring-opening reaction;

[0020] The straight-chain hexadecanoic acid ester with free radicals is contacted with (Z)-9-octadecenoic acid to obtain a branched polycarboxylic acid ester mixture;

[0021] The branched polycarboxylic acid ester mixture is subjected to hydrolysis reaction and acidification treatment to obtain a branched polycarboxylic acid;

[0022] The branched polycarboxylic acid is subjected to ammoniation treatment to obtain the branched polycarboxylic acid ammonium mixture.

[0023] The preparation method is simple and easy, and the obtained products can be used as solutes of working electrolytes without separation and purification. The process is simple, the product yield is high, the cost is low, and it is safe and environmentally friendly.

[0024] According to an embodiment of the present invention, the ring-opening reaction comprises: the cyclohexanone is contacted with a catalyst and an oxidant in a first solvent.

[0025] According to an embodiment of the present invention, the first solvent includes at least one of methanol, anhydrous methanol, ethanol, n-butanol, isopropanol, and tert-butanol.

[0026] According to an embodiment of the present invention, the molar ratio of the cyclohexanone to the first solvent is 1:(0.5-20).

[0027] According to an embodiment of the present invention, the catalyst includes at least one of nitric acid, sulfuric acid and hydrochloric acid.

[0028] According to an embodiment of the present invention, the oxidant includes at least one of sodium persulfate, hydrogen peroxide, potassium peroxide, and sodium peroxide.

[0029] According to an embodiment of the present invention, the molar ratio of the cyclohexanone to the oxidant and the catalyst is 1:(0.1-2):(0.01-0.2).

[0030] According to an embodiment of the present invention, the temperature of the ring-opening reaction is -10°C to 5°C.

[0031] According to an embodiment of the present invention, the ring-opening reaction time is 10 to 120 minutes.

[0032] According to an embodiment of the present invention, the straight-chain hexadecanoic acid ester with free radicals is contacted with (Z)-9-octadecenoic acid and a reducing agent to obtain a branched polycarboxylic acid ester mixture.

[0033] According to an embodiment of the present invention, the reducing agent includes at least one of cuprous chloride, cuprous sulfate, ferrous chloride, ferrous sulfate, ferrous sulfate heptahydrate, sodium sulfite, and potassium sulfite.

[0034] According to an embodiment of the present invention, the molar ratio of the cyclohexanone to the reducing agent is 1:(0.2-5).

[0035] According to an embodiment of the present invention, the molar ratio of cyclohexanone to (Z)-9-octadecenoic acid is 1:(0.8-1.2).

[0036] According to an embodiment of the present invention, the hydrolysis reaction comprises dissolving the branched polycarboxylic acid ester mixture in an alkaline solution.

[0037] According to an embodiment of the present invention, the alkaline substance in the alkaline solution includes at least one of sodium carbonate, sodium hydroxide, potassium carbonate and potassium hydroxide.

[0038] According to an embodiment of the present invention, the ammonium treatment comprises contacting the branched polycarboxylic acid with at least one of ammonia, dimethylamine, diethylamine, and triethylamine.

[0039] According to an embodiment of the present invention, the branched polycarboxylic acid is subjected to ammoniation treatment in a second solvent to obtain the branched polycarboxylic acid ammonium mixture;

[0040] The second solvent includes ethylene glycol.

[0041] The third aspect of the present invention provides an electrolyte, comprising a main solute, wherein the main solute comprises the electrolyte solute described in the first aspect, or the electrolyte solute obtained according to the preparation method described in the second aspect.

[0042] Therefore, the electrolyte has higher electrical conductivity and flash voltage, which can improve the high and low temperature resistance, voltage resistance, safety and stability of the capacitor.

[0043] According to an embodiment of the present invention, it further includes auxiliary solute, main solvent, auxiliary solvent and additives.

[0044] According to an embodiment of the present invention, in the electrolyte, the mass proportion of the main solute is 5% to 30%, the mass proportion of the auxiliary solute is 1% to 7%, the mass proportion of the main solvent is 40% to 70%, the mass proportion of the auxiliary solvent is 5% to 20%, and the mass proportion of the additive is 5% to 30%.

[0045] According to an embodiment of the present invention, the main solvent includes ethylene glycol.

[0046] According to an embodiment of the present invention, the auxiliary solvent includes at least one of ethylene glycol, diethylene glycol, propylene glycol, glycerol, n-butanol, n-octanol, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ether, diethylene glycol diethyl ether, γ-butyrolactone, polyethylene glycol, and butyl acetate.

[0047] According to an embodiment of the present invention, the auxiliary solute includes at least one of boric acid, ammonium borate, formic acid, ammonium formate, 2-butyl suberic acid, 2-butyl ammonium suberate, dodecanedioic acid, ammonium dodecanedioic acid, azelaic acid, ammonium azelate, sebacic acid, ammonium sebacate, tricosane branched dicarboxylic acids and their ammonium salts, and polymeric carboxylic acids and their ammonium salts.

[0048] According to an embodiment of the present invention, the additive includes at least one of a flash enhancer, a hydrogen remover, and a waterproof mixture.

[0049] According to an embodiment of the present invention, the flash enhancer includes at least one of polyethylene glycol, polypropylene glycol, polypropylene alcohol, polymerized fatty acid, polymerized fatty acid ammonium, and nano inorganic oxide.

[0050] According to an embodiment of the present invention, the hydrogen remover includes at least one of resorcinol, p-nitrophenol, p-nitrobenzyl alcohol, o-nitroanisole, and p-benzoquinone.

[0051] According to an embodiment of the present invention, the waterproof mixture includes at least one of phosphoric acid, ammonium phosphate, hypophosphorous acid, ammonium hypophosphite, a silicic acid compound, an aluminum salt, and mannitol.

[0052] A fourth aspect of the present invention provides an aluminum electrolytic capacitor, comprising the electrolyte described in the third aspect.

[0053] Therefore, the aluminum electrolytic capacitor has good high and low temperature resistance, voltage resistance, safety and stability, etc.

[0054] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. DETAILED DESCRIPTION

[0055] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0056] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0057] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0058] In order to make the present invention more easily understood, certain technical and scientific terms are specifically defined below. Unless otherwise clearly defined elsewhere in this document, all other technical and scientific terms used herein have the meanings commonly understood by those skilled in the art to which the present invention belongs.

[0059] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention but not excluding other contents.

[0060] As used herein, the terms "optionally", "optional" or "optionally" generally mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0061] According to an embodiment of the present invention, a first aspect of the present invention provides an electrolyte solute, comprising a branched polycarboxylic acid ammonium mixture, wherein the branched polycarboxylic acid ammonium mixture comprises 7,7'-(octadecane-9,10-diethyl) dioctyl ammonium pentadecanedioate, 8-(5-carboxypentyl)-7-octane hexadecane dioate, 10,11-dioctyl ammonium eicosanedioate, 8-hydroxy-7-octane hexadecane dioate, (E)-7-hexadecane-8-octyl ammonium enedioate, and ammonium dodecanedioate.

[0062] The inventors found that due to the steric hindrance of the side chain groups and the polarization of the alkoxy groups, the solubility and thermal stability of the branched polycarboxylates in the solvent are better than those of the straight-chain carboxylates, and they have strong chemical repair ability. Therefore, the branched polycarboxylates can be used to manufacture aluminum electrolytic capacitors with low impedance and high ripple current resistance. At the same time, the branched polycarboxylic acid ammonium compound provided by the present invention has good solubility, and each branched polycarboxylic acid ammonium salt has a synergistic effect, which can significantly improve the conductivity and flash voltage of the electrolyte, as well as the high and low temperature resistance, pressure resistance, safety and stability of the capacitor.

[0063] According to a specific embodiment of the present invention, the mass proportion of the 7,7'-(octadecane-9,10-diethyl) dioctyl pentadecanedioic acid ammonium in the branched polycarboxylic acid ammonium mixture is 65% to 82%. As some specific examples, its mass proportion may be 65%, 70%, 75%, 80%, 82%, etc. Specifically, the structural formula of 7,7'-(octadecane-9,10-diethyl) dioctyl pentadecanedioic acid ammonium is:

[0064]

[0065] According to a specific embodiment of the present invention, the mass proportion of the 8-(5-carboxypentyl)-7-octane hexadecane dioic acid ammonium in the branched polycarboxylic acid ammonium mixture is 8% to 20%. As some specific examples, its mass proportion may be 8%, 10%, 12%, 14%, 16%, 18%, 20%, etc. Specifically, the structural formula of 8-(5-carboxypentyl)-7-octane hexadecane dioic acid ammonium is:

[0066]

[0067] According to a specific embodiment of the present invention, the mass proportion of the 10,11-dioctyl ammonium eicosane dioic acid in the branched polycarboxylic acid ammonium mixture is 5% to 14%. As some specific examples, its mass proportion may be 5%, 6%, 8%, 10%, 12%, 14%, etc. Specifically, the structural formula of 10,11-dioctyl ammonium eicosane dioic acid is:

[0068]

[0069] According to a specific embodiment of the present invention, the mass proportion of 8-hydroxy-7-octane hexadecane dioic acid ammonium in the branched polycarboxylic acid ammonium mixture is 3% to 10%. As some specific examples, its mass proportion may be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc. Specifically, the structural formula of 8-hydroxy-7-octane hexadecane dioic acid ammonium is:

[0070]

[0071] According to a specific embodiment of the present invention, the mass proportion of (E)-7-hexadec-8-octylenedioic acid ammonium in the branched polycarboxylic acid ammonium mixture is 1% to 5%. As some specific examples, its mass proportion may be 1%, 2%, 3%, 4%, 5%, etc. Specifically, the structural formula of (E)-7-hexadec-8-octylenedioic acid ammonium is:

[0072]

[0073] According to a specific embodiment of the present invention, the mass proportion of ammonium dodecane dioate in the branched polycarboxylate ammonium mixture is 0.5% to 2%. As some specific examples, its mass proportion may be 0.5%, 1%, 2%, etc. Specifically, the structure of ammonium dodecane dioate is:

[0074]

[0075] According to an embodiment of the present invention, the second aspect of the present invention provides a method for preparing the electrolyte solute according to the first aspect, comprising the following steps of preparing a branched polycarboxylic acid ammonium mixture:

[0076] (1) Cyclohexanone undergoes a ring-opening reaction to give a straight-chain hexadecanoic acid ester with a free radical.

[0077]

[0078] Specifically, the ring-opening reaction comprises: the cyclohexanone is contacted with a catalyst and an oxidant in a first solvent, the cyclohexanone generates a hemiketal under the action of the catalyst, and reacts with the oxidant to generate an oxidative ring-opening reaction to generate free radicals.

[0079] According to a specific embodiment of the present invention, the type of the first solvent is not particularly limited, and those skilled in the art can select it according to actual conditions. As some specific examples, the first solvent includes but is not limited to methanol, anhydrous methanol, ethanol, n-butanol, isopropanol, and tert-butanol. The molar ratio of the cyclohexanone to the first solvent is 1:(0.5-20), and can be specifically 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, etc.

[0080] According to a specific embodiment of the present invention, the catalyst is an acidic catalyst, including but not limited to nitric acid, sulfuric acid, and hydrochloric acid. The type of the oxidant is not particularly limited, and those skilled in the art can select it according to actual conditions. As some specific examples, the oxidant includes but is not limited to sodium persulfate, hydrogen peroxide, potassium peroxide, and sodium peroxide. The molar ratio of the cyclohexanone to the oxidant and the catalyst is 1:(0.1-2):(0.01-0.2), specifically 1:0.1:0.01, 1:0.2:0.02, 1:0.3:0.03, 1:0.4:0.04, 1:0.5:0.05, 1:0.9:0.05, 1:1:0.2, 1:1:0.05, 1:1:0.1, 1:2:0.1, 1:2:0.2, etc.

[0081] According to a specific embodiment of the present invention, the temperature and time of the ring-opening reaction are not particularly limited. As some specific examples, the temperature of the ring-opening reaction may be -10°C to 5°C, for example, -10°C, -5°C, 0°C, 5°C, etc.; the time of the ring-opening reaction may be 10 to 120 min, for example, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, etc.

[0082] (2) The straight-chain hexadecanoic acid ester with free radicals is contacted with (Z)-9-octadecenoic acid to obtain a branched polycarboxylic acid ester mixture.

[0083] The straight-chain hexadecanoic acid ester with free radical undergoes free radical addition reaction with (Z)-9-octadecenoic acid to generate a branched polycarboxylic acid ester mixture.

[0084] According to a specific embodiment of the present invention, the straight-chain hexadecanoic acid ester with free radicals is contacted with (Z)-9-octadecenoic acid and a reducing agent to obtain a branched polycarboxylic acid ester mixture. The type of the reducing agent is not particularly limited, including but not limited to cuprous chloride, cuprous sulfate, ferrous chloride, ferrous sulfate, ferrous sulfate heptahydrate, sodium sulfite, and potassium sulfite.

[0085] According to a specific embodiment of the present invention, the molar ratio of the cyclohexanone to the reducing agent is 1:(0.2-5), such as 1:0.2, 1:0.5, 1:0.95, 1:1.0, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, etc. The molar ratio of the cyclohexanone to the (Z)-9-octadecenoic acid is 1:(0.8-1.2). As some specific examples, the molar ratio of the cyclohexanone to the (Z)-9-octadecenoic acid can be 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, etc., preferably 1:1.0.

[0086] According to a specific embodiment of the present invention, in this step, after the reaction, water extraction is performed to remove the reducing agent, and distillation is performed to remove the solvent to obtain a relatively pure branched polycarboxylic acid ester mixture.

[0087] (3) The branched polycarboxylic acid ester mixture is subjected to hydrolysis reaction and acidification treatment to obtain a branched polycarboxylic acid.

[0088] According to a specific embodiment of the present invention, the hydrolysis reaction comprises dissolving the branched polycarboxylic acid ester mixture in an alkaline solution. The alkaline substance in the alkaline solution is not particularly limited, and includes but is not limited to sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide. The acidification treatment comprises mixing the solution after the hydrolysis reaction with an acidic solution, and the acidic substance in the acidic solution is also not particularly limited, and includes but is not limited to dilute sulfuric acid, hydrochloric acid, etc.

[0089] (4) The branched polycarboxylic acid is subjected to ammonium treatment to obtain the branched polycarboxylic acid ammonium mixture.

[0090] According to a specific embodiment of the present invention, the ammonium treatment comprises contacting the branched polycarboxylic acid with at least one of ammonia, dimethylamine, diethylamine, and triethylamine. Specifically, the branched polycarboxylic acid is ammonium treated in a second solvent to obtain the branched polycarboxylic acid ammonium mixture, and the second solvent is preferably ethylene glycol.

[0091] According to an embodiment of the present invention, a third aspect of the present invention provides an electrolyte, comprising a main solute, wherein the main solute comprises the electrolyte solute described in the first aspect, or the electrolyte solute obtained according to the preparation method described in the second aspect.

[0092] The electrolyte includes the aforementioned electrolyte solute, so that the working electrolyte prepared with the solute has the advantages of higher voltage resistance and heat resistance stability.

[0093] According to a specific embodiment of the present invention, the electrolyte further includes an auxiliary solute, a main solvent, an auxiliary solvent and an additive. Specifically, in the electrolyte, the proportion of each component is not particularly limited. As some specific examples, the mass proportion of the main solute is 5% to 30%, such as 5%, 10%, 15%, 20%, 25%, 30%, etc.; the mass proportion of the auxiliary solute is 1% to 7%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, etc.; the mass proportion of the main solvent is 40% to 70%, such as 40%, 50%, 60%, 70%, etc.; the mass proportion of the auxiliary solvent is 5% to 20%, such as 5%, 10%, 15%, 20%, etc.; the mass proportion of the additive is 5% to 30%, such as 5%, 10%, 15%, 20%, 25%, 30%, etc.

[0094] Specifically, the main solvent includes but is not limited to ethylene glycol.

[0095] Specifically, the auxiliary solvent includes but is not limited to at least one of ethylene glycol, diethylene glycol, propylene glycol, glycerol, n-butanol, n-octanol, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ether, diethylene glycol diethyl ether, γ-butyrolactone, polyethylene glycol, and butyl acetate.

[0096] Specifically, the auxiliary solute includes but is not limited to at least one of boric acid, ammonium borate, formic acid, ammonium formate, 2-butyl suberic acid, 2-butyl ammonium suberate, dodecanedioic acid, ammonium dodecanedioic acid, azelaic acid, ammonium azelate, sebacic acid, ammonium sebacate, tricosane branched dicarboxylic acids and their ammonium salts, and polymeric carboxylic acids and their ammonium salts.

[0097] Specifically, the additives include but are not limited to flash-promoting agents, dehydrogenating agents, and waterproofing agents. As some specific examples, the flash-promoting agents include but are not limited to at least one of polyethylene glycol, polypropylene glycol, polypropylene alcohol, polymerized fatty acids, polymerized fatty acid ammonium, and nano inorganic oxides. The dehydrogenating agents include but are not limited to at least one of resorcinol, p-nitrophenol, p-nitrobenzyl alcohol, o-nitroanisole, and p-benzoquinone. The waterproofing agents include but are not limited to at least one of phosphoric acid, ammonium phosphate, hypophosphorous acid, ammonium hypophosphite, silicic acid compounds, aluminum salts, and mannitol.

[0098] According to an embodiment of the present invention, a fourth aspect of the present invention provides an aluminum electrolytic capacitor, comprising the electrolyte described in the third aspect.

[0099] Therefore, the aluminum electrolytic capacitor has good high and low temperature resistance, voltage resistance, safety and stability, etc.

[0100] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.

[0101] Example 1

[0102] Preparation of branched polycarboxylic acid ammonium mixture:

[0103] (1) Add 256 g (8 mol) of anhydrous methanol and 98 g (1 mol) of cyclohexanone to a 1000 mL three-necked flask; set the cooling bath to -10°C and place the flask in the cooling bath to cool down; slowly drop 0.05 mol of concentrated sulfuric acid from a dropping funnel into the flask, keeping the temperature at -10 to 0°C, and stirring for 15 min after the addition is complete; slowly drop 111 g of 27.5% hydrogen peroxide from a dropping funnel into the flask, keeping the temperature at -10 to 0°C, and stirring for 15 min after the addition is complete;

[0104] (2) Add 226.0 g (0.8 mol) of (Z)-9-octadecenoic acid into the flask, keep the temperature at -10 to 0°C, and stir for 15 min; slowly add ferrous sulfate heptahydrate into the flask, keep the temperature at -10 to 0°C, and stir for 15 min;

[0105] The material is transferred into a separating funnel and allowed to stand for stratification, the upper layer is the product, and the lower layer of waste liquid is discharged; the upper layer product is washed with pure water to remove impurity ions in the product, and the washing waste water is discharged; the washed upper layer product is distilled to remove the solvent, so as to obtain a relatively pure branched polycarboxylic acid ester mixture;

[0106] (3) adding the branched polycarboxylic acid ester mixture to 380 g of a sodium hydroxide solution having a mass concentration of 10%, heating the mixture to about 98° C., reflux reacting the mixture for 4 h, cooling the mixture and filtering the reaction solution to obtain a clear branched polycarboxylic acid sodium salt solution;

[0107] (4) adding 180 g of 50% by mass dilute sulfuric acid to the clarified branched polycarboxylic acid sodium salt solution for acidification, stirring for 30 min, and allowing the layers to stand until the pH value of the lower aqueous phase is less than 2; the upper layer is the desired product, and the lower layer is the waste liquid; thus, the branched polycarboxylic acid is obtained;

[0108] (5) The branched polycarboxylic acid is purified to remove ions and prepared into a 10% ethylene glycol solution, into which ammonia gas is introduced for ammoniation, with the end point being a pH value of about 7.0, thereby obtaining an ethylene glycol solution containing a branched polycarboxylic acid ammonium mixture.

[0109] 200 mL of electrolyte was prepared according to the following formula, and the water content, conductivity, pH, flash voltage, and low-temperature storage performance of the electrolyte were tested.

[0110] Table 1

[0111]

[0112]

[0113] Example 2

[0114] Preparation of branched polycarboxylic acid ammonium mixture:

[0115] (1) Add 256 g (8 mol) of anhydrous methanol and 98 g (1 mol) of cyclohexanone to a 1000 mL three-necked flask; set the cooling bath at 10°C and place the flask in the cooling bath to cool down; slowly drop 0.05 mol of concentrated sulfuric acid from a dropping funnel into the flask, keeping the temperature at 10-0°C, and stirring for 15 min after the addition is complete; slowly drop 111 g of 27.5% hydrogen peroxide from a dropping funnel into the flask, keeping the temperature at 10-0°C, and stirring for 15 min after the addition is complete;

[0116] (2) Add 254.2 g (0.9 mol) of (Z)-9-octadecenoic acid into the flask, keep the temperature at 10-0°C, and stir for 15 min; slowly add ferrous sulfate heptahydrate into the flask, keep the temperature at 10-0°C, and stir for 15 min;

[0117] The material is transferred into a separating funnel and allowed to stand for stratification, the upper layer is the product, and the lower layer of waste liquid is discharged; the upper layer product is washed with pure water to remove impurity ions in the product, and the washing waste water is discharged; the washed upper layer product is distilled to remove the solvent, so as to obtain a relatively pure branched polycarboxylic acid ester mixture;

[0118] (3) adding the branched polycarboxylic acid ester mixture to 380 g of a sodium hydroxide solution having a mass concentration of 10%, heating the mixture to about 98° C., reflux reacting the mixture for 4 h, cooling the mixture and filtering the reaction solution to obtain a clear branched polycarboxylic acid sodium salt solution;

[0119] (4) Add 180 g of 50% by mass concentration dilute sulfuric acid to the clarified branched polycarboxylic acid sodium salt solution for acidification, stir for 30 min, and allow the layers to stand until the pH value of the lower aqueous phase is less than 2; the upper layer is the desired product, and the lower layer is the waste liquid; thus, the branched polycarboxylic acid is obtained;

[0120] (5) The branched polycarboxylic acid is purified to remove ions and prepared into a 10% ethylene glycol solution, into which ammonia gas is introduced for ammoniation, with the end point being a pH value of about 7.0, thereby obtaining an ethylene glycol solution of a branched polycarboxylic acid ammonium mixture.

[0121] 200 mL of electrolyte was prepared according to the following formula, and the water content, conductivity, pH, flash voltage, and low-temperature storage performance of the electrolyte were tested.

[0122] Table 2

[0123]

[0124]

[0125] Example 3

[0126] Preparation of branched polycarboxylic acid ammonium mixture:

[0127] (1) Add 256 g (8 mol) of anhydrous methanol and 98 g (1 mol) of cyclohexanone to a 1000 mL three-necked flask; set the cooling bath to -10°C and place the flask in the cooling bath to cool down; slowly drop 0.05 mol of concentrated sulfuric acid from a dropping funnel into the flask, keeping the temperature at -10 to 0°C, and stirring for 15 min after the addition is complete; slowly drop 111 g of 27.5% hydrogen peroxide from a dropping funnel into the flask, keeping the temperature at -10 to 0°C, and stirring for 15 min after the addition is complete;

[0128] (2) Add 282.5 g (1.0 mol) of (Z)-9-octadecenoic acid into a flask, keep the temperature at -10 to 0°C, and stir for 15 min; slowly add ferrous sulfate heptahydrate into the flask, keep the temperature at -10 to 0°C, and stir for 15 min;

[0129] The material is transferred into a separating funnel and allowed to stand for stratification, the upper layer is the product, and the lower layer of waste liquid is discharged; the upper layer product is washed with pure water to remove impurity ions in the product, and the washing waste water is discharged; the washed upper layer product is distilled to remove the solvent, so as to obtain a relatively pure branched polycarboxylic acid ester mixture;

[0130] (3) The branched polycarboxylic acid ester mixture is added to 380 g of a sodium hydroxide solution having a mass concentration of 10%, the temperature is raised to about 98° C., the reaction mixture is refluxed for 4 h, the temperature is lowered, and the reaction solution is filtered to obtain a clear branched polycarboxylic acid sodium salt solution.

[0131] (4) Add 180 g of 50% by mass concentration dilute sulfuric acid to the clarified branched polycarboxylic acid sodium salt solution for acidification, stir for 30 min, and allow the layers to stand until the pH value of the lower aqueous phase is less than 2; the upper layer is the desired product, and the lower layer is the waste liquid; thus, the branched polycarboxylic acid is obtained;

[0132] (5) The branched polycarboxylic acid is purified to remove ions and prepared into a 10% ethylene glycol solution, into which ammonia gas is introduced for ammoniation, with the end point being a pH value of about 7.0, thereby obtaining an ethylene glycol solution of a branched polycarboxylic acid ammonium mixture.

[0133] 200 mL of electrolyte was prepared according to the following formula, and the water content, conductivity, pH, flash voltage, and low-temperature storage performance of the electrolyte were tested.

[0134] Table 3

[0135] Material Content (by mass) / % Ethylene glycol 55 Diethylene glycol monobutyl ether 10 PEG1000 5 Boric acid 2 Ammonium hypophosphite 1 p-Nitrobenzyl alcohol 0.5 Mannitol 1.5 2-Butyl ammonium suberate 5 Example 3 Branched polycarboxylic acid ammonium mixture prepared 20

[0136] Example 4

[0137] Preparation of branched polycarboxylic acid ammonium mixture:

[0138] (1) Add 256 g (8 mol) of anhydrous methanol and 98 g (1 mol) of cyclohexanone to a 1000 mL three-necked flask; set the cooling bath at 10°C and place the flask in the cooling bath to cool down; slowly drop 0.05 mol of concentrated sulfuric acid from a dropping funnel into the flask, keeping the temperature at 10-0°C, and stirring for 15 min after the addition is complete; slowly drop 111 g of 27.5% hydrogen peroxide from a dropping funnel into the flask, keeping the temperature at 10-0°C, and stirring for 15 min after the addition is complete;

[0139] (2) Add 310.7 g (1.1 mol) of (Z)-9-octadecenoic acid into the flask, keep the temperature at 10-0°C, and stir for 15 min; slowly add ferrous sulfate heptahydrate into the flask, keep the temperature at 10-0°C, and stir for 15 min;

[0140] The material is transferred into a separating funnel and allowed to stand for stratification, the upper layer is the product, and the lower layer of waste liquid is discharged; the upper layer product is washed with pure water to remove impurity ions in the product, and the washing waste water is discharged; the washed upper layer product is distilled to remove the solvent, so as to obtain a relatively pure branched polycarboxylic acid ester mixture;

[0141] (3) adding the branched polycarboxylic acid ester mixture to 380 g of a sodium hydroxide solution having a mass concentration of 10%, heating the mixture to about 98° C., reflux reacting the mixture for 4 h, cooling the mixture and filtering the reaction solution to obtain a clear branched polycarboxylic acid sodium salt solution;

[0142] (4) Add 180 g of 50% by mass concentration dilute sulfuric acid to the clarified branched polycarboxylic acid sodium salt solution for acidification, stir for 30 min, and allow the layers to stand until the pH value of the lower aqueous phase is less than 2; the upper layer is the desired product, and the lower layer is the waste liquid; thus, the branched polycarboxylic acid is obtained;

[0143] (5) The branched polycarboxylic acid is purified to remove ions and prepared into a 10% ethylene glycol solution, into which ammonia gas is introduced for ammoniation, with the end point being a pH value of about 7.0, thereby obtaining an ethylene glycol solution of a branched polycarboxylic acid ammonium mixture.

[0144] 200 mL of electrolyte was prepared according to the following formula, and the water content, conductivity, pH, flash voltage, and low-temperature storage performance of the electrolyte were tested.

[0145] Table 4

[0146] Material Content (by mass) / % Ethylene glycol 55 Diethylene glycol monobutyl ether 10 PEG1000 5 Boric acid 2 Ammonium hypophosphite 1 p-Nitrobenzyl alcohol 0.5 Mannitol 1.5 2-Butyl ammonium suberate 5 Example 4: Branched-chain polycarboxylic acid ammonium mixture prepared 20

[0147] Comparative Example 1

[0148] 200 mL of electrolyte was prepared according to the following formula, and the water content, conductivity, pH, flash voltage, and low-temperature storage performance of the electrolyte were tested.

[0149] Table 5

[0150]

[0151]

[0152] Comparative Example 2

[0153] 200 mL of electrolyte was prepared according to the following formula, and the water content, conductivity, pH, flash voltage, and low-temperature storage performance of the electrolyte were tested.

[0154] Table 6

[0155] Material Content (by mass) / % Ethylene glycol 55 Diethylene glycol monobutyl ether 10 PEG1000 5 Boric acid 2 Ammonium hypophosphite 1 p-Nitrobenzyl alcohol 0.5 Mannitol 1.5 2-Butyl ammonium suberate 5 Polycarboxylic acid 20

[0156] The test results are shown in the table below. The test results in Table 7 show that, compared with commercially available tricosane branched dicarboxylic acid ammonium salts and polymeric carboxylic acids, the branched polycarboxylic acid ammonium mixture of the present invention can significantly improve the flash voltage and conductivity of the electrolyte and make it have excellent low temperature performance.

[0157] Table 7

[0158]

[0159] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" 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 representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0160] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. An electrolyte solute, characterized in that The invention comprises a branched polycarboxylic acid ammonium mixture, wherein the branched polycarboxylic acid ammonium mixture comprises 7,7'-(octadecane-9,10-diethyl) dioctyl ammonium pentadecanedioate, 8-(5-carboxypentyl)-7-octane hexadecane dioate, 10,11-dioctyl ammonium eicosanedioate, 8-hydroxy-7-octane hexadecane dioate, (E)-7-hexadecane-8-octyl ammonium enedioate, and ammonium dodecanedioate.

2. The electrolyte solute according to claim 1, characterized in that The mass proportion of the 7,7'-(octadecane-9,10-diethyl) dioctylpentadecanedioic acid ammonium in the branched polycarboxylate ammonium mixture is 65% to 82%; The mass proportion of the 8-(5-carboxypentyl)-7-octane hexadecane dicarboxylic acid ammonium is 8% to 20%; The mass proportion of the 10,11-dioctyl ammonium eicosanedioate is 5% to 14%; The mass proportion of the 8-hydroxy-7-octane hexadecane dioic acid ammonium is 3% to 10%; The mass proportion of the (E)-7-hexadec-8-octylenedioic acid ammonium is 1% to 5%; The mass proportion of the ammonium dodecanedioate is 0.5% to 2%.

3. A method for preparing an electrolyte solute according to claim 1 or 2, characterized in that: The method comprises the following steps of preparing a branched polycarboxylic acid ammonium mixture: Cyclohexanone can be used to obtain a straight-chain hexadecanoic acid ester with a free radical through a ring-opening reaction; The straight-chain hexadecanoic acid ester with free radicals is contacted with (Z)-9-octadecenoic acid to obtain a branched polycarboxylic acid ester mixture; The branched polycarboxylic acid ester mixture is subjected to hydrolysis reaction and acidification treatment to obtain a branched polycarboxylic acid; The branched polycarboxylic acid is subjected to ammoniation treatment to obtain the branched polycarboxylic acid ammonium mixture.

4. The preparation method according to claim 3, characterized in that: The ring-opening reaction comprises: contacting the cyclohexanone with a catalyst and an oxidant in a first solvent; Optionally, the first solvent includes at least one of methanol, anhydrous methanol, ethanol, n-butanol, isopropanol, and tert-butanol; Optionally, the molar ratio of the cyclohexanone to the first solvent is 1:(0.5-20); Optionally, the catalyst includes at least one of nitric acid, sulfuric acid, and hydrochloric acid; Optionally, the oxidant includes at least one of sodium persulfate, hydrogen peroxide, potassium peroxide, and sodium peroxide; Optionally, the molar ratio of the cyclohexanone to the oxidant and the catalyst is 1:(0.1-2):(0.01-0.2); Optionally, the temperature of the ring-opening reaction is -10°C to 5°C; Optionally, the ring-opening reaction time is 10 to 120 minutes.

5. The preparation method according to claim 3, characterized in that: The straight-chain hexadecanoic acid ester with free radicals is contacted with (Z)-9-octadecenoic acid and a reducing agent to obtain a branched polycarboxylic acid ester mixture; Optionally, the reducing agent includes at least one of cuprous chloride, cuprous sulfate, ferrous chloride, ferrous sulfate, ferrous sulfate heptahydrate, sodium sulfite, and potassium sulfite; Optionally, the molar ratio of the cyclohexanone to the reducing agent is 1:(0.2-5); Optionally, the molar ratio of cyclohexanone to (Z)-9-octadecenoic acid is 1:(0.8-1.2).

6. The preparation method according to claim 3, characterized in that: The hydrolysis reaction comprises dissolving the branched polycarboxylic acid ester mixture in an alkaline solution; Optionally, the alkaline substance in the alkaline solution includes at least one of sodium carbonate, sodium hydroxide, potassium carbonate and potassium hydroxide.

7. The preparation method according to claim 3, characterized in that: The ammonium treatment comprises contacting the branched polycarboxylic acid with at least one of ammonia, dimethylamine, diethylamine, and triethylamine; Optionally, the branched polycarboxylic acid is subjected to an ammoniation treatment in a second solvent to obtain the branched polycarboxylic acid ammonium mixture; The second solvent includes ethylene glycol.

8. An electrolyte, characterized in that: It comprises a main solute, and the main solute comprises the electrolyte solute according to claim 1 or 2, or the electrolyte solute obtained according to the preparation method according to any one of claims 3-7.

9. The electrolyte according to claim 8, characterized in that It also includes auxiliary solutes, primary solvents, auxiliary solvents and additives; Optionally, in the electrolyte, the mass proportion of the main solute is 5% to 30%, the mass proportion of the auxiliary solute is 1% to 7%, the mass proportion of the main solvent is 40% to 70%, the mass proportion of the auxiliary solvent is 5% to 20%, and the mass proportion of the additive is 5% to 30%; Optionally, the main solvent comprises ethylene glycol; Optionally, the auxiliary solvent includes at least one of ethylene glycol, diethylene glycol, propylene glycol, glycerol, n-butanol, n-octanol, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ether, diethylene glycol diethyl ether, γ-butyrolactone, polyethylene glycol, and butyl acetate; Optionally, the auxiliary solute includes at least one of boric acid, ammonium borate, formic acid, ammonium formate, 2-butyl suberic acid, 2-butyl ammonium suberate, dodecanedioic acid, ammonium dodecanedioate, azelaic acid, ammonium azelate, sebacic acid, ammonium sebacate, tricosane branched dicarboxylic acids and ammonium salts thereof, polymeric carboxylic acids and ammonium salts thereof; Optionally, the additive includes at least one of a flash enhancer, a hydrogen remover, and a waterproofing agent; Optionally, the flash enhancer includes at least one of polyethylene glycol, polypropylene glycol, polypropylene alcohol, polymerized fatty acid, polymerized fatty acid ammonium, and nano inorganic oxide; Optionally, the hydrogen remover includes at least one of resorcinol, p-nitrophenol, p-nitrobenzyl alcohol, o-nitroanisole, and p-benzoquinone; Optionally, the waterproof mixture includes at least one of phosphoric acid, ammonium phosphate, hypophosphorous acid, ammonium hypophosphite, silicic acid compounds, aluminum salts, and mannitol.

10. An aluminum electrolytic capacitor, characterized in that: Comprising the electrolyte described in claim 8 or 9.

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