Electrolyte for high-voltage aluminum electrolytic capacitor and high-voltage aluminum electrolytic capacitor

Abstract

In order to overcome the problems of existing aluminum electrolytic capacitors being easily corroded and failing under high voltage and having a short lifespan, the present application provides an electrolyte for high-voltage aluminum electrolytic capacitors and a high-voltage aluminum electrolytic capacitor, the electrolyte main solute B, the anti-corrosion material A and the solvent, and the electrolyte satisfies the following relationship: 0.1≤10 3 ×(σ×m×p) / (r×η)≤1.5, and 1%≤m≤5%, 80mPa·s≤η≤400mPa·s. The prepared electrolyte has high conductivity and flash voltage, which can avoid failure phenomena such as breakdown, valve leakage, and corrosion of the capacitor. The prepared aluminum electrolytic capacitor can withstand high voltage above 500V, has high conductivity, high voltage resistance and good corrosion resistance, and its service life reaches 5000 hours at 105℃.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolyte for aluminum electrolytic capacitors, and in particular relates to an electrolyte for high-voltage aluminum electrolytic capacitors above 500V and a high-voltage aluminum electrolytic capacitor. Background Art

[0002] Aluminum electrolytic capacitors have a wide range of applications, encompassing key sectors such as industry, home appliances, and aerospace, playing an irreplaceable and important role. As their use expands, the requirements for their withstand voltage have also gradually increased. Currently, aluminum electrolytic capacitors in the 500-600V voltage range on the market often use capacitors with lower conductivity to ensure their withstand voltage. For example, the electrolyte used in 500V, 550V, and 600V electrolytic capacitors has an electrolyte conductivity of 1.2mS / cm, 1.0mS / cm, and 0.6mS / cm, respectively. While low-conductivity electrolytes can effectively meet high withstand voltage requirements, their application in aluminum electrolytic capacitors results in a relatively high DF (dielectric loss, DF = lost energy / stored energy) value, which can lead to excessive heat generation during use and shorten the product's lifespan.

[0003] At the same time, aluminum electrolytic capacitors operate under high voltage, creating a strong electric field. This can accelerate the migration of impurity ions and cause them to migrate out of the aluminum matrix lattice, accelerating corrosion of the aluminum foil and affecting capacitor parameters. In severe cases, this can lead to capacitor failure. Currently, the service life of high-voltage aluminum electrolytic capacitors on the market is generally marked as 2000 hours at 105°C. The main reason for this is that aluminum capacitors are more susceptible to corrosion failure in the later stages of use. Summary of the Invention

[0004] In order to solve the problem that existing aluminum electrolytic capacitors are prone to corrosion failure and short life under high voltage, the present application provides an electrolyte for high-voltage aluminum electrolytic capacitors and a high-voltage aluminum electrolytic capacitor.

[0005] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0006] In one aspect, the present invention provides an electrolyte for a high-voltage aluminum electrolytic capacitor, the electrolyte comprising a solvent, a solute, and an additive, the solute comprising a main solute B and an anti-corrosion material A, the main solute B being a compound represented by structural formula 1:

[0007]

[0008] Wherein, R includes a main carbon chain and a branch located on the main carbon chain, the main carbon chain of R includes a length of 10 to 26 carbon atoms, the number of R branches is 1 to 10, and the branches of R are each independently selected from a straight-chain or branched hydrocarbon group with 1 to 10 carbon atoms, and a straight-chain or branched oxygen-containing hydrocarbon group with 1 to 10 carbon atoms;

[0009] The electrolyte satisfies the following relationship:

[0010] 0.1≤10 3 ×(σ×m×p) / (r×η)≤1.5;

[0011] And 1%≤m≤5%, 80mPa·s≤η≤400mPa·s;

[0012] Wherein: σ: conductivity of the electrolyte at 25°C, unit: mS / cm;

[0013] m: water content of the electrolyte, unit %;

[0014] p: mass content of main solute B in the electrolyte, unit %;

[0015] r: mass content of anti-corrosion material A in the electrolyte, unit %;

[0016] η: viscosity of the electrolyte, unit: mPa·s.

[0017] Preferably, the oxygen-containing hydrocarbon group includes a carbonyl group, an ester group or a carboxyl group.

[0018] Preferably, the water content m of the electrolyte is 2% to 4%.

[0019] Preferably, the viscosity η of the electrolyte is 80 mPa·s≤η≤300 mPa·s.

[0020] Preferably, based on the total mass of the electrolyte being 100%, the mass content of the main solute B in the electrolyte is 10% to 25%.

[0021] Preferably, the anti-corrosion material A is a complex obtained by reacting an inorganic acid with a polyol in an ethylene glycol solvent;

[0022] The inorganic acid includes one or more of boric acid, molybdic acid and silicic acid; the polyol includes one or more of mannitol, xylitol, sorbitol and quercetin;

[0023] Preferably, the anti-corrosion material A is a complex of boric acid and mannitol;

[0024] Taking the total mass of the electrolyte as 100%, the mass content of the anti-corrosion material A in the electrolyte is 8% to 15%.

[0025] Preferably, the solvent includes a main solvent and a co-solvent, and the main solvent includes one or more of ethylene glycol, diethylene glycol, and glycerol;

[0026] The cosolvent includes one or more of N,N-dimethylformamide, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ether, γ-butyrolactone, cyclopentane, and n-butanol;

[0027] Based on the total mass of the electrolyte being 100%, the mass content of the main solvent in the electrolyte is 26% to 65.49%; the mass content of the auxiliary solvent in the electrolyte is 8% to 15%.

[0028] Preferably, the electrolyte further comprises an auxiliary solute, and the auxiliary solute comprises one or more of sebacic acid and its ammonium salt, azelaic acid and its ammonium salt, dodecanedioic acid and its ammonium salt, boric acid, and ammonium pentaborate;

[0029] Based on the total mass of the electrolyte being 100%, the mass content of the auxiliary solute in the electrolyte is 1% to 3%.

[0030] Preferably, the additives include a hydrogen remover, a waterproofing agent and a flash fire enhancer;

[0031] The hydrogen remover includes one or more of p-nitrobenzyl alcohol, m-nitroacetophenone, o-nitroanisole, p-nitrophenol, ammonium p-nitrobenzoate, and p-nitrobenzoic acid;

[0032] The waterproofing mixture includes one or more of ammonium hypophosphite, hypophosphorous acid, sorbitol, mannitol, silicic acid compounds, and aluminum silicate;

[0033] The flash enhancer comprises one or more of polyethylene glycol, polypropylene glycol, propylene glycol block polyether, polyacrylamide, polyvinyl alcohol, and inorganic nano-silica with a molecular weight of 600 to 6000;

[0034] Based on the total mass of the electrolyte being 100%, the mass content of the hydrogen remover in the electrolyte is 0.5% to 2%; the mass content of the waterproof mixture in the electrolyte is 0.01% to 2%; and the mass content of the flash enhancer in the electrolyte is 7% to 12%.

[0035] On the other hand, the present application provides a high-voltage aluminum electrolytic capacitor, comprising an anode foil, a cathode foil, and electrolytic paper arranged on the same side of the anode foil and the cathode foil, wherein the electrolytic paper is soaked with an electrolyte, and the electrolyte is the electrolyte for the high-voltage aluminum electrolytic capacitor described above.

[0036] Beneficial effects:

[0037] The water content in the electrolyte is between 1% and 5%, which can provide sufficient oxygen negative ions, improve the oxidation efficiency of the anode foil, and repair the oxide film in time, thereby increasing the service life of the aluminum electrolytic capacitor; the water content of the electrolyte is controlled between 1% and 5%, and the viscosity of the electrolyte is within the range of 80mPa·s to 400mPa·s, which has the effects of increasing the ion migration rate, maintaining the electrolyte with high conductivity, and ensuring good infiltration effect of the core inclusion impregnation; the electrolyte for high-voltage aluminum electrolytic capacitors provided in this application adjusts the conductivity and viscosity of the electrolyte by controlling the water content m, the main solute B content p, and the anti-corrosion material A content r in the electrolyte, so that the relationship 0.1≤10 is satisfied. 3 ×(σ×m×p) / (r×η)≤1.5, and 1%≤m≤5%, 80mPa·s≤η≤400mPa·s. The prepared electrolyte has high conductivity and flash voltage, which can avoid failure phenomena such as breakdown, valve leakage, and corrosion of the capacitor. The prepared aluminum electrolytic capacitor can withstand high voltage above 500V and has a service life of 5000H at 105℃. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] An embodiment of the present application provides an electrolyte for a high-voltage aluminum electrolytic capacitor, the electrolyte comprising a solvent, a solute, and an additive, the solute comprising a main solute B and an anti-corrosion material A, the main solute B being a compound represented by structural formula 1:

[0040]

[0041] Wherein, R includes a main carbon chain and a branch located on the main carbon chain, the main carbon chain length of R is 10 to 26 carbon atoms, the number of R branches is 1 to 10, and the branches of R are each independently selected from a straight chain or branched hydrocarbon group with 1 to 10 carbon atoms, and a straight chain or branched oxygen-containing hydrocarbon group with 1 to 10 carbon atoms;

[0042] The electrolyte satisfies the following relationship:

[0043] 0.1≤10 3 ×(σ×m×p) / (r×η)≤1.5;

[0044] And 1%≤m≤5%, 80mPa·s≤η≤400mPa·s;

[0045] Wherein: σ: conductivity of the electrolyte at 25°C (mS / cm);

[0046] m: water content of the electrolyte (%);

[0047] p: mass content of main solute B in the electrolyte (%);

[0048] r: mass content of anti-corrosion material A in the electrolyte (%);

[0049] η: viscosity of the electrolyte (mPa·s).

[0050] Specifically, the branch chain of R on the main solute B can be selected from a C1-C10 straight-chain hydrocarbon group, such as methyl, ethyl, propyl, octyl, etc. The branch chain of R can also be a branched hydrocarbon group with 1-10 carbon atoms, such as isopropyl, isobutyl, etc. The branch chain of R on the main solute B can also be selected from a straight-chain or branched oxygen-containing hydrocarbon group with 1-10 carbon atoms, such as methyl acetate, methyl propionate, etc.

[0051] In some preferred embodiments, the oxygen-containing hydrocarbon group includes a carboxyl group, a carbonyl group or an ester group; for example, the carboxyl group can be an acetyl group, a propionyl group or other group containing one carboxyl group, or can be a group containing two or more carboxyl groups; the carbonyl group can be a formyl group, an acetyl group, an isobutyryl group or the like; the ester group can be ethyl acetate, propyl acetate, propyl propionate or the like.

[0052] The main solute B can be one or more of the following compounds:

[0053]

[0054] The main solute B serves as a high-voltage electrolyte. The main carbon chain length of R in the compound shown in Structural Formula 1 ranges from 10 to 26 carbon atoms. As the carbon chain length increases, the long-chain carboxylate ammonium salt adheres to the oxide film surface, effectively protecting the oxide film's weak points in terms of pressure resistance, causing the electrolyte's flashover voltage to gradually increase with the length of the carbon chain. The main solute B has good solubility in the electrolyte solvent, improving the electrolyte's conductivity and facilitating the electrochemical reaction of the capacitor. However, it should be noted that the amount of main solute B added significantly affects the viscosity of the electrolyte. Excessively high electrolyte viscosity reduces ion migration rates and is detrimental to the impregnation process during capacitor manufacturing. Therefore, the content of main solute B in the electrolyte not only depends on the desired conductivity, but also ensures that the electrolyte viscosity is within the range of 80 mPa·s ≤ η ≤ 400 mPa·s, more preferably 80 mPa·s ≤ η ≤ 300 mPa·s.

[0055] In some preferred embodiments, based on the total mass of the electrolyte being 100%, the mass content of the main solute B in the electrolyte is 10% to 25%.

[0056] The electrolyte contains a certain amount of water, which helps to ionize the main solute in the electrolyte, thereby improving the conductivity of the electrolyte to a certain extent. At the same time, water can also improve the oxygen supply capacity of the electrolyte, which helps to repair the dielectric layer. From this perspective, a water content of more than 1% in the electrolyte is appropriate. In addition, if the electrolyte contains more water, it is easy to form a hydrated film Al(OH)3 on the surface of the foil, resulting in a decrease in the capacitor capacity. At the same time, due to the low boiling point of water, when the capacitor is used under high temperature conditions, the internal pressure increases, causing the valve to open and leak and fail. In addition, excessive water content in the electrolyte makes it easier for sulfate and chloride ions to precipitate, increasing the risk of capacitor corrosion. Therefore, the maximum water content in the electrolyte does not exceed 5%, and can be 1%, 1.5%, 2%, 2.5%, 2.8%, 3.2%, 3.6%, 4.2%, 4.5%, 5.0%, and preferably 2% to 4%.

[0057] In some preferred embodiments, the anti-corrosion material A is a complex obtained by reacting an inorganic acid with a polyol in an ethylene glycol solvent;

[0058] The inorganic acid includes one or more of boric acid, molybdic acid and silicic acid; the polyol includes one or more of mannitol, xylitol, sorbitol and quercetin;

[0059] In some preferred embodiments, the anti-corrosion material A is a complex of boric acid and mannitol; based on the total mass of the electrolyte being 100%, the mass content of the anti-corrosion material A in the electrolyte is 8% to 15%.

[0060] The amount of anti-corrosion material A added to the electrolyte can be 8%, 8.5%, 9.0%, 9.6%, 10.4%, 10.9%, 11.5%, 12%, 12.6%, 13%, 13.8%, 14%, 14.3%, or 15%. Anti-corrosion material A, when applied to the electrolyte, has an anti-corrosion effect. When used as a working electrolyte in high-voltage aluminum electrolytic capacitors, the electrolyte can prevent impurity ions from corroding the aluminum foil, thereby improving the corrosion resistance of the capacitor. Furthermore, anti-corrosion material A can react with water to adjust the moisture content of the electrolyte, effectively resolving stability issues associated with increased moisture content in the capacitor.

[0061] The electrolyte for the high-voltage aluminum electrolytic capacitor provided in this application satisfies the relationship 0.1≤10 3×(σ×m×p) / (r×η)≤1.5, where σ is the conductivity of the electrolyte, m is the water content in the electrolyte, p is the content of the main solute B, r is the content of the anti-corrosion material A, η is the viscosity of the electrolyte, and 1%≤m≤5%, 80mPa·s≤η≤400mPa·s. It has excellent conductivity and high flash voltage, which meets the requirements of capacitors with a maximum operating voltage of 500V. The prepared capacitor has good corrosion resistance, and the life test reaches 105℃5000H, with high reliability.

[0062] In some preferred embodiments, the solvent includes a main solvent and a co-solvent, and the main solvent includes one or more of ethylene glycol, diethylene glycol, and propylene glycol; the main solvent is mostly selected from alcohol compounds, which can ensure good solubility for the main solute B, anti-corrosion material A, auxiliary solute, and additives.

[0063] The cosolvent includes one or more of N,N-dimethylformamide, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ether, γ-butyrolactone, cyclopentane sulfone, and n-butanol; the cosolvent cooperates with the main solvent to increase the solubility of the main solute B, the anti-corrosion material A, the additive, etc., and stabilize the solvent.

[0064] In some preferred embodiments, based on the total mass of the electrolyte being 100%, the mass content of the main solvent in the electrolyte is 26% to 65.49%; the mass content of the auxiliary solvent in the electrolyte is 8% to 15%.

[0065] The amount of main solvent added accounts for a relatively large proportion, and it mainly plays the role of dissolving the main solute B, anti-corrosion material A, auxiliary solute, additives and other solutes. The amount of co-solvent added is lower than that of the main solvent, and it plays the role of assisting the main solvent in dissolving the solute. The two work together to increase the solubility and stability of the solvent.

[0066] In some preferred embodiments, the electrolyte further includes an auxiliary solute, and the auxiliary solute includes one or more of sebacic acid and its ammonium salt, azelaic acid and its ammonium salt, dodecanedioic acid and its ammonium salt, boric acid, and ammonium pentaborate;

[0067] Based on the total mass of the electrolyte being 100%, the mass content of the auxiliary solute in the electrolyte is 1% to 3%.

[0068] The amount of auxiliary solute added can be 1%, 1.5%, 1.7%, 2.0%, 2.3%, 2.5%, 2.7%, or 3.0%. The amount of auxiliary solute added is between 1% and 3%, and the auxiliary solute is used to improve the conductivity of the electrolyte.

[0069] In some preferred embodiments, the electrolyte further comprises additives, wherein the additives include a hydrogen remover, a waterproofing agent, and a flash fire enhancer;

[0070] The hydrogen scavenger includes one or more of p-nitrobenzyl alcohol, m-nitroacetophenone, o-nitroanisole, p-nitrophenol, ammonium p-nitrobenzoate, and p-nitrobenzoic acid. Since the electrolyte repairs the oxide film on the anode foil and generates hydrogen, the hydrogen scavenger mainly reacts with the hydrogen through the hydrogen scavenging compound to reduce the hydrogen in the aluminum electrolytic capacitor and prevent explosion caused by excessive hydrogen.

[0071] The waterproofing mixture includes one or more of ammonium hypophosphite, hypophosphorous acid, sorbitol, mannitol, silicic acid compounds, and aluminum silicate; substances such as phosphate and silicate are added to the waterproofing mixture to the electrolyte of the aluminum capacitor. These substances present in the electrolyte can form a passivation layer on the surface of the aluminum oxide film, thereby effectively inhibiting hydration.

[0072] The flash enhancer includes one or more of polyethylene glycol, polypropylene glycol, propylene glycol block polyether, polyacrylamide, polyvinyl alcohol, and inorganic nano-silica with a molecular weight of 600 to 6000; the flash enhancer can increase the flash voltage of the electrolyte to ensure that the electrolytic paper will not be broken down due to electrolyte flash when the capacitor is overvoltage.

[0073] Based on the total mass of the electrolyte as 100%, the mass content of the hydrogen remover in the electrolyte is 0.5% to 2%. The added amount of the hydrogen remover can be 0.5%, 1%, 1.5%, or 2%. As long as the added amount of the hydrogen remover is between 0.5% and 2%, it can effectively eliminate hydrogen generated in the capacitor and improve the capacitor's safety performance. Based on the total mass of the electrolyte as 100%, the mass content of the waterproofing mixture in the electrolyte is 0.01% to 2%. The added amount of the waterproofing mixture can be 0.01%, 0.5%, 1.0%, 1.5%, or 2.0%. As long as the added amount of the waterproofing mixture is between 0.01% and 2%, the hydration inhibition effect is fully exerted. Taking the total mass of the electrolyte as 100%, the mass content of the flash enhancer in the electrolyte is 7% to 12%, and the added amount of the flash enhancer can be 7%, 8%, 9%, 10%, 11%, or 12%. As long as the added amount of the flash enhancer is between 7% and 12%, the flash voltage of the electrolyte is increased to ensure that the capacitor will not be broken down due to electrolyte flash when overvoltage occurs.

[0074] On the other hand, the present application provides a high-voltage aluminum electrolytic capacitor, comprising an anode foil, a cathode foil, and electrolytic paper arranged on the same side of the anode foil and the cathode foil, wherein the electrolytic paper is soaked with an electrolyte, and the electrolyte is the electrolyte for the high-voltage aluminum electrolytic capacitor described above.

[0075] The high-voltage aluminum electrolytic capacitor uses the above electrolyte, and the aluminum electrolytic capacitor prepared has the characteristics of high conductivity, high voltage resistance, and excellent corrosion resistance.

[0076] The present invention is further described below with reference to the following examples.

[0077] Table 1 Specific compounds corresponding to different numbers of main solute B and anticorrosive material A

[0078] category Specific compounds Main solute B1 Compound 1 Main solute B2 Compound 2 Main solute B3 Compound 3 Anti-corrosion material A1 Complex of boric acid and mannitol Anti-corrosion material A2 Complex of boric acid and sorbitol Anti-corrosion material A3 Complex of silicic acid and mannitol

[0079] Example 1

[0080] A method for preparing an electrolyte for a high-voltage aluminum electrolytic capacitor comprises the following steps:

[0081] The main solvent is ethylene glycol with a mass content of 55.5%, the auxiliary solvent is γ-butyrolactone with a mass content of 8%, the main solute B is B1 compound with a mass content of 15%, the auxiliary solute is ammonium pentaborate with a mass content of 1.5%, the flash enhancer is polyvinyl alcohol 105 with a mass content of 2%, nano-silicon dioxide with a mass content of 6%, the added water mass content is 1.0%, the anti-corrosion material A is A1 compound with a mass content of 10%, the dehydrogenation agent is p-nitrobenzyl alcohol with a mass content of 0.5%, and the waterproofing agent is ammonium hypophosphite with a mass content of 0.5%; then they are mixed evenly to form an electrolyte for high-voltage aluminum electrolytic capacitors.

[0082] Example 2

[0083] A method for preparing an electrolyte for a high-voltage aluminum electrolytic capacitor comprises the following steps:

[0084] The main solvent is selected from diethylene glycol with a mass content of 35.5%, the auxiliary solvent is selected from N,N-dimethylformamide with a mass content of 15%, the main solute B is B2 compound with a mass content of 20%, the auxiliary solute is dodecanedioic acid ammonium with a mass content of 2.3%, the flash enhancer is selected from polyvinyl alcohol 2000 with a mass content of 2.5%, nano-silicon dioxide with a mass content of 6%, the added water has a mass content of 2.3%, the anti-corrosion material A is selected from A2 compound with a mass content of 15%, the dehydrogenation agent is selected from p-nitrobenzoic acid with a mass content of 1.2%, and the waterproofing agent is selected from sorbitol with a mass content of 0.2%; and then they are mixed evenly to form an electrolyte for high-voltage aluminum electrolytic capacitors.

[0085] Example 3

[0086] A method for preparing an electrolyte for a high-voltage aluminum electrolytic capacitor comprises the following steps:

[0087] The main solvent is selected from 40% by mass of propylene glycol, the auxiliary solvent is selected from 10% by mass of diethylene glycol monobutyl ether, the main solute B is 18% by mass of B3 compound, the auxiliary solute is 2.8% by mass of azelaic acid, the flash enhancer is selected from 2.1% by mass of polyacrylamide, 6.6% by mass of polyethylene glycol 1000, the added water content is 2.8% by mass, the anti-corrosion material A is selected from 15% by mass of A3 compound, the dehydrogenation agent is selected from 1.6% by mass of m-nitroacetophenone, and the waterproofing agent is selected from 1.1% by mass of aluminum silicate; then they are mixed evenly to form an electrolyte for high-voltage aluminum electrolytic capacitors.

[0088] Example 4

[0089] A method for preparing an electrolyte for a high-voltage aluminum electrolytic capacitor comprises the following steps:

[0090] The main solvent is ethylene glycol with a mass content of 55%, the auxiliary solvent is butyrolactone with a mass content of 12.5%, the main solute B is B1 compound with a mass content of 10%, the auxiliary solute is ammonium sebacate with a mass content of 1%, the flash enhancer is polyethylene glycol 2000 with a mass content of 10%, the added water mass content is 4.2%, the anti-corrosion material A is A1 compound with a mass content of 20%, the dehydrogenation agent is p-nitrophenol with a mass content of 2%, and the waterproofing agent is mannitol with a mass content of 1.8%; then they are mixed evenly to form an electrolyte for high-voltage aluminum electrolytic capacitors.

[0091] Example 5

[0092] A method for preparing an electrolyte for a high-voltage aluminum electrolytic capacitor comprises the following steps:

[0093] The main solvent is selected from diethylene glycol with a mass content of 40%, the auxiliary solvent is selected from n-butanol with a mass content of 8%, the main solute B is a B2 compound with a mass content of 10%, the auxiliary solute is a nonanedioic acid with a mass content of 1.5%, the flash enhancer is selected from polyvinyl alcohol 105 with a mass content of 4%, nano-silicon dioxide with a mass content of 4%, the added water mass content is 5.0%, the anti-corrosion material A is selected from A1 compound with a mass content of 25%, the dehydrogenation agent is selected from ammonium p-nitrobenzoate with a mass content of 1.1%, and the waterproofing agent is selected from hypophosphorous acid with a mass content of 1.4%; then they are mixed evenly to form an electrolyte for high-voltage aluminum electrolytic capacitors.

[0094] Example 6

[0095] A method for preparing an electrolyte for a high-voltage aluminum electrolytic capacitor comprises the following steps:

[0096] The main solvent is selected from ethylene glycol with a mass content of 49.3%, the auxiliary solvent is selected from cyclopentane with a mass content of 14%, the main solute B is a B1 compound with a mass content of 11%, the flash enhancer is selected from polyvinyl alcohol 105 with a mass content of 6%, polyethylene glycol 2000 with a mass content of 5%, the added water mass content is 1.2%, the anti-corrosion material A is selected from A2 compound with a mass content of 10%, the dehydrogenation agent is selected from p-nitrophenol with a mass content of 2%, and the waterproofing agent is selected from ammonium hypophosphite with a mass content of 1.5%; then they are mixed evenly to form an electrolyte for high-voltage aluminum electrolytic capacitors.

[0097] Example 7

[0098] A method for preparing an electrolyte for a high-voltage aluminum electrolytic capacitor comprises the following steps:

[0099] The main solvent is selected from ethylene glycol with a mass content of 41.9%, the auxiliary solvent is selected from butyrolactone with a mass content of 11%, the main solute B is a B3 compound with a mass content of 13%, the flash enhancer is selected from polyvinyl alcohol 105 with a mass content of 10%, the added water mass content is 2.1%, the anti-corrosion material A is selected from A3 compound with a mass content of 20%, and the hydrogen scavenger is selected from m-nitroacetophenone with a mass content of 2%; then they are mixed evenly to form an electrolyte for high-voltage aluminum electrolytic capacitors.

[0100] Comparative Example 1

[0101] A method for preparing an electrolyte for a high-voltage aluminum electrolytic capacitor comprises the following steps:

[0102] The main solvent is ethylene glycol with a mass content of 47.5%, the auxiliary solvent is γ-butyrolactone with a mass content of 8%, the main solute B is B1 compound with a mass content of 15%, the auxiliary solute is ammonium dodecanoate with a mass content of 2.5%, the flash enhancer is polyethylene glycol 2000 with a mass content of 2.5%, nano-silicon dioxide with a mass content of 6%, the added water mass content is 0.5%, the anti-corrosion material A is A1 compound with a mass content of 17%, the dehydrogenation agent is p-nitrobenzyl alcohol with a mass content of 0.5%, and the waterproofing agent is ammonium hypophosphite with a mass content of 0.5%; then they are mixed evenly to form an electrolyte for high-voltage aluminum electrolytic capacitors.

[0103] Comparative Example 2

[0104] A method for preparing an electrolyte for a high-voltage aluminum electrolytic capacitor comprises the following steps:

[0105] The main solvent is 63% ethylene glycol, the auxiliary solvent is 8% γ-butyrolactone, the main solute B is 10% B1 compound, the auxiliary solute is 2.5% dodecanedioic acid ammonium, the flash enhancer is 2.5% polyethylene glycol 2000, 6% nano-silica, the added water content is 2%, the anti-corrosion material A is 5% A1 compound, the dehydrogenation agent is 0.5% p-nitrobenzyl alcohol, and the waterproofing agent is 0.5% ammonium hypophosphite; and then they are mixed evenly to form an electrolyte for high-voltage aluminum electrolytic capacitors.

[0106] Comparative Example 3

[0107] A method for preparing an electrolyte for a high-voltage aluminum electrolytic capacitor comprises the following steps:

[0108] The main solvent is selected from ethylene glycol with a mass content of 29.5%, the auxiliary solvent is selected from γ-butyrolactone with a mass content of 8%, the main solute B is a B1 compound with a mass content of 15%, the auxiliary solute is dodecanedioic acid ammonium with a mass content of 2.5%, the flash enhancer is polyethylene glycol 2000 with a mass content of 2.5%, nano-silica with a mass content of 6%, the added water has a mass content of 5.5%, the anti-corrosion material A is selected from A2 compound with a mass content of 30%, the dehydrogenation agent is selected from p-nitrobenzyl alcohol with a mass content of 0.5%, and the waterproofing agent is selected from ammonium hypophosphite with a mass content of 0.5%; and then the components are mixed evenly to form an electrolyte for high-voltage aluminum electrolytic capacitors.

[0109] Comparative Example 4

[0110] A method for preparing an electrolyte for a high-voltage aluminum electrolytic capacitor comprises the following steps:

[0111] The main solvent is selected from ethylene glycol with a mass content of 62%, the auxiliary solvent is selected from γ-butyrolactone with a mass content of 12%, the main solute B is a B1 compound with a mass content of 5%, the auxiliary solute is dodecanedioic acid ammonium with a mass content of 2.5%, the flash enhancer is polyethylene glycol 2000 with a mass content of 2.5%, nano-silicon dioxide with a mass content of 6%, the added water mass content is 1.0%, the anti-corrosion material A is selected from A1 compound with a mass content of 8%, the dehydrogenation agent is selected from p-nitrobenzyl alcohol with a mass content of 0.5%, and the waterproofing agent is selected from ammonium hypophosphite with a mass content of 0.5%; and then the components are mixed evenly to form an electrolyte for high-voltage aluminum electrolytic capacitors.

[0112] The viscosity, conductivity, water content, and flash voltage of the electrolytes prepared in Examples 1-7 and Comparative Examples 1-4 were tested at 25° C. The specific test results are shown in Table 2.

[0113] Table 2 Electrolysis test data of Examples 1-7 and Comparative Examples 1-4

[0114]

[0115] The electrolytes of Examples 1-7 and Comparative Examples 1-4 were used as working electrolytes to prepare aluminum electrolytic capacitors, including the following steps: a battery cell including an anode foil, a cathode foil, and electrolytic paper made of aluminum foil was immersed in the electrolytes of Comparative Examples 1-4 and Examples 1-7, respectively, and sealed with an aluminum shell and colloid particles to obtain a high-voltage aluminum electrolytic capacitor.

[0116] The electrolytes prepared in Examples 1-7 and Comparative Examples 1-4 were used as working electrolytes in aluminum electrolytic capacitors to prepare aluminum electrolytic capacitors. The capacitors were subjected to a 105°C high-temperature load life test. The specific tests were as follows:

[0117] Examples 1-7 and Comparative Examples 1-4 were subjected to life verification using 500V 470μF, 35×50 core packages. Ten capacitors were tested for each example. The test results are shown in Table 3.

[0118] The measurement results are shown in Table 3, where Cap is the capacitance of the capacitor, ΔC is the capacitance decay rate of the capacitor before and after the DC load life test, DF is the dielectric loss, and LC is the leakage current.

[0119] Aluminum electrolyte capacitor life test parameter qualification standard: ΔC within ±20%, DF dielectric loss ≤40%.

[0120] Table 3 Life test performance data of Examples 1-7 and Comparative Examples 1-4

[0121]

[0122]

[0123] From Table 1-3, we know that the water content of the electrolyte in Comparative Example 1 is insufficient, and the viscosity of the electrolyte is too high, resulting in low electrolyte conductivity, low capacitance of the prepared capacitor, and excessive loss. In the subsequent life test, excessive heat generation leads to serious failure of the capacitor due to valve opening and leakage. Adjust the water content in the electrolyte, such as in Example 1-7, increase the water content in the electrolyte, reduce the viscosity of the electrolyte, increase the flashover voltage of the electrolyte, and the prepared capacitor has no leakage abnormality in the 105°C life test. Compared with Comparative Example 1, the content of anti-corrosion material A in the electrolyte of Comparative Example 2 is reduced, resulting in a decrease in the flashover voltage of the electrolyte. Although Comparative Example 2 increases the water content and improves the conductivity of the electrolyte, the content of anti-corrosion material A added is not enough, which makes the electrolyte relationship 10 3The value of ×(σ×m×p) / (r×η) is too large, and the prepared capacitor fails in corrosion and breakdown during the life test. Comparative Example 3 adds excess water relative to Comparative Example 2, and at the same time adds a sufficient amount of anti-corrosion material A, so that the electrolyte relationship formula 10 3 ×(σ×m×p) / (r×η) is within the range of 0.1 to 1.5, but the conductivity of the electrolyte is still very low. This is because the proportion of solvent in the electrolyte is too low, resulting in low conductivity of the electrolyte. During the capacitor life test, the valve opened and leaked, and the life span was short. It is speculated that the water content in the electrolyte is high. The presence of water in the electrolyte will cause the degradation of the dielectric film layer and increase the internal vapor pressure of the electrolyte capacitor. The damage of the sealing part and the evaporation of the electrolyte will shorten the life span and cannot maintain long-term stability. Comparative Example 4 increases the solvent content compared to Comparative Example 3. However, because the content of the main solute B in the electrolyte is too low, the addition of water to the electrolyte does not improve the conductivity of the electrolyte. The viscosity of the electrolyte is also low. During the capacitor life test, there are valve opened leakage failure and breakdown failure.

[0124] From the above comparative examples 1-4 and examples 1-7, it is known that the electrolyte not only needs to satisfy the water content of 1% to 5% and the viscosity of 80 to 400 mP·s, but also the conductivity σ, water content m, main solute B content p, anti-corrosion material A content r, and electrolyte viscosity η in the electrolyte need to satisfy the relationship 0.1≤10 3 ×(σ×m×p) / (r×η)≤1.5. Only when these three conditions are met at the same time can the prepared electrolyte have higher conductivity and flash voltage, avoiding capacitor breakdown, valve leakage, corrosion and other failure phenomena. The prepared aluminum electrolytic capacitor can withstand high voltage above 500V, has high conductivity, high voltage resistance and good corrosion resistance, and its service life reaches 5000H at 105℃.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An electrolyte for a high-voltage aluminum electrolytic capacitor, characterized in that: The electrolyte includes a solvent, a solute and an additive, wherein the solute includes a main solute B and an anti-corrosion material A, and the main solute B is a compound shown in structural formula 1: Structural formula 1 Wherein, R includes a main carbon chain and a branch located on the main carbon chain, the main carbon chain of R includes a length of 10 to 26 carbon atoms, the number of R branches is 1 to 10, and the branches of R are each independently selected from a straight-chain or branched hydrocarbon group with 1 to 10 carbon atoms, and a straight-chain or branched oxygen-containing hydrocarbon group with 1 to 10 carbon atoms; the anti-corrosion material A is a complex obtained by reacting an inorganic acid and a polyol in an ethylene glycol solvent, and the mass content of the anti-corrosion material A in the electrolyte is 8% to 15% based on the total mass of the electrolyte as 100%; Based on the total mass of the electrolyte being 100%, the mass content of the main solute B in the electrolyte is 10% to 25%; The electrolyte satisfies the following relationship: 0.1≤10 3 ×(σ×m×p) / (r×η)≤1.5; And 1%≤m≤5%, 80mPa·s≤η≤400mPa·s; Wherein, σ: conductivity of the electrolyte at 25°C, unit: mS / cm; m: water content of the electrolyte, unit: %; p: mass content of main solute B in the electrolyte, unit: %; r: mass content of anti-corrosion material A in the electrolyte, unit: %; η: viscosity of the electrolyte, unit: mPa•s.

2. The electrolyte for high-voltage aluminum electrolytic capacitors according to claim 1, wherein The oxygen-containing hydrocarbon group includes a carbonyl group, an ester group or a carboxyl group.

3. The electrolyte for high-voltage aluminum electrolytic capacitors according to claim 1, wherein The water content m of the electrolyte is 2% to 4%.

4. The electrolyte for high-voltage aluminum electrolytic capacitors according to claim 1, wherein The viscosity η of the electrolyte is 80 mPa·s≤η≤300 mPa·s.

5. The electrolyte for high-voltage aluminum electrolytic capacitors according to claim 1, wherein The inorganic acid includes one or more of boric acid, molybdic acid and silicic acid; the polyol includes one or more of mannitol, xylitol, sorbitol and quercetin.

6. The electrolyte for high-voltage aluminum electrolytic capacitors according to claim 1, wherein The anti-corrosion material A is a complex of boric acid and mannitol.

7. The electrolyte for high-voltage aluminum electrolytic capacitors according to claim 1, wherein The solvent includes a main solvent and a co-solvent, and the main solvent includes one or more of ethylene glycol, diethylene glycol, and glycerol; The cosolvent includes one or more of N,N-dimethylformamide, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ether, γ-butyrolactone, cyclopentane, and n-butanol; Based on the total mass of the electrolyte being 100%, the mass content of the main solvent in the electrolyte is 26% to 65.49%; the mass content of the auxiliary solvent in the electrolyte is 8% to 15%.

8. The electrolyte for high-voltage aluminum electrolytic capacitors according to claim 1, wherein The electrolyte further includes an auxiliary solute, which includes one or more of sebacic acid and its ammonium salt, azelaic acid and its ammonium salt, dodecanedioic acid and its ammonium salt, boric acid, and ammonium pentaborate; Based on the total mass of the electrolyte being 100%, the mass content of the auxiliary solute in the electrolyte is 1% to 3%.

9. The electrolyte for high-voltage aluminum electrolytic capacitors according to claim 1, wherein The additives include hydrogen remover, waterproofing agent and flash fire enhancer; The hydrogen remover includes one or more of p-nitrobenzyl alcohol, m-nitroacetophenone, o-nitroanisole, p-nitrophenol, ammonium p-nitrobenzoate, and p-nitrobenzoic acid; The waterproofing mixture includes one or more of ammonium hypophosphite, hypophosphorous acid, sorbitol, mannitol, silicic acid compounds, and aluminum silicate; The flash enhancer comprises one or more of polyethylene glycol, polypropylene glycol, propylene glycol block polyether, polyacrylamide, polyvinyl alcohol, and inorganic nano-silica with a molecular weight of 600 to 6000; Based on the total mass of the electrolyte as 100%, the mass content of the hydrogen remover in the electrolyte is 0.5% to 2%; the mass content of the waterproof mixture in the electrolyte is 0.01% to 2%; and the mass content of the flash enhancer in the electrolyte is 7% to 12%.

10. A high voltage aluminum electrolytic capacitor, characterized in that: The invention comprises an anode foil, a cathode foil and electrolytic paper arranged on the same side of the anode foil and the cathode foil, wherein the electrolytic paper is soaked with an electrolyte, and the electrolyte is the electrolyte for high-voltage aluminum electrolytic capacitors according to any one of claims 1 to 9.

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