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

Abstract

The application discloses a kind of electrolyte for middle-high voltage aluminum electrolytic capacitor and aluminum electrolytic capacitor, belong to electrochemistry technical field, including solute, solvent and additive, solute includes cycloalkene carboxylic acid ammonium salt compound, additive includes inorganic boron compound, wherein cycloalkene carboxylic acid ammonium salt compound structural formula is as formula (1) or formula (2), wherein wherein A is hydrogen atom or the group of 1-10 carbon atom-containing hydrocarbon group, carboxyl, carboxylic acid ammonium group;Wherein B is hydrogen atom or 1-10 carbon atom-containing hydrocarbon group;And x+y value is 0-30, cycloalkene carboxylic acid ammonium salt compound and inorganic boron compound are combined as electrolyte, wherein boron-containing compound is as buffer agent, prevents cycloalkene carboxylic acid ammonium salt compound decomposition, to form relatively ideal electrolyte.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and more specifically, to an electrolyte for medium- and high-voltage aluminum electrolytic capacitors and an aluminum electrolytic capacitor. Background Technology

[0002] Aluminum electrolytic capacitors are one of the fundamental components of electronic products, widely used in the production of automotive electronics, frequency converters, displays, chargers, electronic ballasts, switching power supplies, and energy-saving lamps. In recent years, the rapid development of electronic technology and the further improvement of integration have placed higher demands on the comprehensive performance of aluminum electrolytic capacitors, driving their development towards high voltage, high capacitance, and long lifespan.

[0003] Aluminum electrolytic capacitors are mainly composed of a capacitor core and a working electrolyte. The working electrolyte plays a crucial role in the performance of aluminum electrolytic capacitors, determining their operating temperature range, rated voltage, loss factor, impedance, rated ripple current, and service life.

[0004] Currently, most working electrolytes for medium and high voltage aluminum electrolytic capacitors are systems consisting of straight-chain ammonium carboxylate salts, borate salts, and ethylene glycol. The more carbon atoms in a straight-chain carboxylate, the higher the flash voltage. However, its solubility decreases sharply with increasing molecular weight. For example, the solubility of commonly used ammonium sebate in ethylene glycol is less than 5%, and it easily crystallizes at low temperatures, limiting the capacitor's operating temperature range. Branched polycarboxylate salts have relatively high solubility in multi-component solvents, are less prone to crystallization at low temperatures, have a wider operating temperature range, and exhibit high electrolyte conductivity. Capacitors made from branched polycarboxylate salts have strong voltage withstand capabilities and high ripple current resistance. However, branched polycarboxylate salts suffer from high cost and insufficient flash voltage performance; for example, a 5% concentration rarely achieves a flash voltage above 500V. In addition, other solutes that can be used as working electrolytes for medium and high voltage aluminum electrolytic capacitors include ammonium azelate, ammonium hydrogen azelate, ammonium sebacate, ammonium dodecanoate and other straight-chain carboxylates, as well as ammonium pentaborate and ammonium benzoate. However, each of them has certain disadvantages. For example, ammonium dodecanoate is not easy to obtain, ammonium pentaborate has a high conductivity, and ammonium benzoate is unstable at high temperatures. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an electrolyte for medium- and high-voltage aluminum electrolytic capacitors and an aluminum electrolytic capacitor itself. Using a cyclic olefin carboxylic acid ammonium salt compound as the solute and adding an inorganic boron compound as a buffer, the resulting electrolyte, when applied to capacitors, exhibits higher thermal stability and longer lifespan. The specific technical solution is as follows:

[0006] An electrolyte for medium- and high-voltage aluminum electrolytic capacitors includes a solute, a solvent, and an additive. The solute includes a cyclic olefin carboxylic acid ammonium salt compound, and the additive includes an inorganic boron compound. The structural formula of the cyclic olefin carboxylic acid ammonium salt compound is shown in formula (1) or formula (2).

[0007]

[0008] Where A is a hydrogen atom or a group consisting of a hydrocarbon group, carboxyl group, or ammonium carboxylate group containing 1-10 carbon atoms; where B is a hydrogen atom or a hydrocarbon group containing 1-10 carbon atoms; x and y are integers, and the value of x+y is 0-30. Studies have found that by adding a boron-containing compound as a buffer to the electrolyte, the decomposition of cyclic olefin ammonium carboxylate compounds can be prevented under high-temperature conditions, thereby improving the high-temperature performance and lifespan of the electrolyte.

[0009] The cyclic olefin carboxylic acid ammonium salt can be obtained by reacting conjugated linoleic acid and its derivatives with an alkenophilic compound via a Diels-Alder reaction, followed by hydrolysis, purification, and ammonia treatment. The conjugated linoleic acid and its derivatives are selected from one of conjugated linoleic acid, methyl conjugated linoleate, ethyl conjugated linoleate, propyl conjugated linoleate, butyl conjugated linoleate, isopropyl conjugated linoleate, formamide conjugated linoleate, and acetamide conjugated linoleate; the alkenophilic compound is selected from acrylic acid and its derivatives, butenoic acid and its derivatives, pentenoic acid and its derivatives, methacrylic acid and its derivatives, maleic acid and its derivatives, maleic anhydride, citrate and its anhydride, and acrylonitrile.

[0010] Preferably, the cycloolefin carboxylate ammonium salt compound is selected from one of 4-hexyl-6-carboxylammono-cyclohex-2-en-1-octanoic acid ammonium, 4-hexyl-5,6-dicarboxylammono-6-methyl-cyclohex-2-en-1-octanoic acid ammonium, 4-hexyl-6-carboxylammono-6-methyl-cyclohex-2-en-1-octanoic acid ammonium, 6-propyl-1,3,5-tricarboxylammono-cyclohex-2-ene, 4-hexyl-5-ethyl-6-carboxylammono-cyclohex-2-en-1-octanoic acid ammonium, and 4-hexyl-5-butyl-6-carboxylammono-cyclohex-2-en-1-octanoic acid ammonium.

[0011] Preferably, the inorganic boron compound is selected from one or more of boric acid, ammonium diborate, ammonium pentaborate, and borate esters.

[0012] Preferably, the amount of the cyclic olefin carboxylate ammonium salt compound added accounts for 0.10-30.00% of the total electrolyte by mass percentage; more preferably, the percentage is 0.50-15.00%.

[0013] Preferably, the inorganic boron compound is added in an amount of 1.00-10.00% of the total electrolyte, and more preferably in an amount of 2.00-5.00%.

[0014] Preferably, the solvent accounts for 60-95% of the total electrolyte, and the solvent is selected from one or more of alcohols, alcohol ethers, amides, sulfones, sulfoxides and esters; preferably, the solvent is ethylene glycol or γ-butyrolactone.

[0015] Preferably, the additive further includes one or more of the following: waterproofing agent, hydrogen scavenger, flashover enhancer, anti-corrosion additive, and leakage current inhibitor.

[0016] Preferably, the waterproofing agent is selected from one or more of hypophosphite, phosphorous acid, phosphoric acid and monoalkyl phosphate, or from one or more of ammonia or amine salts of hypophosphite, phosphorous acid, phosphoric acid and monoalkyl phosphate;

[0017] Preferably, the hydrogen scavenger is selected from one or more of p-nitrophenol, p-nitrobenzyl alcohol, o-nitrosoanisole, and m-nitroacetylbenzene;

[0018] Preferably, the flashover enhancer is selected from one or more of silica molten material, polyvinyl alcohol, polyethylene glycol, polyvinyl borate, polyvinyl phosphate, polyvinylpyrrolidone, and mannitol;

[0019] The corrosion-resistant additive is selected from one or more of nitric acid, EDTA, silver benzoate, and 8-hydroxyquinoline;

[0020] The leakage current inhibitor is selected from one or more of phosphotungstic acid, molybdic tungstic acid, 3,5-dihydroxybenzoic acid, and strontium nitrate.

[0021] Preferably, the waterproofing agent is added at a mass percentage of 0.05-5.00% of the total electrolyte, more preferably 0.10-3.00%.

[0022] Preferably, the amount of hydrogen scavenger added accounts for 0.10-15.00% of the total electrolyte by mass percentage, and more preferably 0.20-4.00%.

[0023] Preferably, the flashover enhancer is added at a mass percentage of 0.20-15.00% of the total electrolyte, more preferably 0.50-10.00%.

[0024] Preferably, the amount of the anti-corrosion additive added accounts for 0.01-5.00% of the total electrolyte by mass percentage, more preferably 0.01-1.00%.

[0025] Preferably, the leakage current inhibitor is added at a mass percentage of 0.01-5.00% of the total electrolyte, more preferably 0.01-1.00%.

[0026] Preferably, the electrolyte further includes other organic carboxylic acids or their ammonium salts besides the cyclic olefin carboxylic acid ammonium salt compound;

[0027] Other organic carboxylic acids or their ammonium salts are selected from one or more of the following: sebacic acid, azelaic acid, benzoic acid, adipic acid, sebacic acid, dodecanoic acid, 1,6-dodecanoic acid, 1,7-sebacic acid and the ammonium salts of the above acids, preferably in an amount of 1.00-20.00% of the total electrolyte.

[0028] The present invention also provides a medium-high voltage aluminum electrolytic capacitor, using the electrolyte for aluminum electrolytic capacitors described above.

[0029] Beneficial effects:

[0030] The beneficial effects of the technical solution of this invention are as follows:

[0031] Cycloolefin carboxylic acid ammonium salt compounds, as electrolyte solutes, have good solubility, low-temperature antifreeze properties, and high electrical conductivity. When used in electrolytes together with inorganic boron compounds, they also exhibit good thermal stability and long lifespan characteristics at high temperatures (especially 125°C). Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0033] This embodiment uses a cyclic olefin carboxylic acid ammonium salt compound as a solute and adds an inorganic boron compound as a buffer to form an electrolyte that, when applied to capacitors, exhibits higher thermal stability and longer lifespan. Specific implementation details are as follows:

[0034] An electrolyte for aluminum electrolytic capacitors includes a solute, a solvent, and an additive, wherein the solute comprises a cyclic olefin carboxylic acid ammonium salt compound, and the additive comprises an inorganic boron compound, wherein the structural formula of the cyclic olefin carboxylic acid ammonium salt compound is shown in formula (1) or formula (2):

[0035]

[0036] Where A is a hydrogen atom or a group consisting of a hydrocarbon group, a carboxyl group, or an ammonium carboxylate group containing 1-10 carbon atoms; where B is a hydrogen atom or a hydrocarbon group containing 1-10 carbon atoms; x and y are integers, and the value of x+y is 0-30.

[0037] In a preferred embodiment, the cycloolefin carboxylate ammonium salt compound is selected from one of 4-hexyl-6-carboxylammono-cyclohex-2-en-1-octanoic acid ammonium, 4-hexyl-5,6-dicarboxammono-6-methyl-cyclohex-2-en-1-octanoic acid ammonium, 4-hexyl-6-carboxylammono-6-methyl-cyclohex-2-en-1-octanoic acid ammonium, 6-propyl-1,3,5-tricarboxammono-cyclohex-2-ene, 4-hexyl-5-ethyl-6-carboxylammono-cyclohex-2-en-1-octanoic acid ammonium, and 4-hexyl-5-butyl-6-carboxylammono-cyclohex-2-en-1-octanoic acid ammonium.

[0038] In a preferred embodiment, the inorganic boron compound is selected from one or more of boric acid, ammonium diborate, ammonium pentaborate, and boric acid polyol esters.

[0039] In a preferred embodiment, the amount of the cyclic olefin carboxylate ammonium salt compound added accounts for 0.10-30.00% of the total electrolyte by mass percentage; preferably, the percentage is 0.50-15.00%.

[0040] In a preferred embodiment, the inorganic boron compound is added in an amount of 1.00-10.00% of the total electrolyte, preferably 2.00-5.00%.

[0041] In a preferred embodiment, the solvent accounts for 60-95% of the total electrolyte by mass percentage, preferably 70-90%. The solvent is selected from one or more of alcohols, alcohol ethers, amides, sulfones, sulfoxides, and esters; preferably, the solvent is ethylene glycol or γ-butyrolactone.

[0042] In a preferred embodiment, the additive also includes one or more of the following: waterproofing agent, hydrogen scavenger, flashover enhancer, anti-corrosion additive, and leakage current inhibitor.

[0043] In a preferred embodiment, the waterproofing agent is selected from one or more of hypophosphite, phosphorous acid, phosphoric acid, and monoalkyl phosphate, or from one or more of ammonia or amine salts of hypophosphite, phosphorous acid, phosphoric acid, and monoalkyl phosphate.

[0044] In a preferred embodiment, the hydrogen scavenger is selected from one or more of p-nitrophenol, p-nitrobenzyl alcohol, o-nitrosoanisole, and m-nitroacetylbenzene;

[0045] In a preferred embodiment, the flashover enhancer is selected from one or more of silica molten material, polyvinyl alcohol, polyethylene glycol, polyvinyl borate, polyvinyl phosphate, polyvinylpyrrolidone, and mannitol;

[0046] The corrosion-resistant additive is selected from one or more of nitric acid, EDTA, silver benzoate, and 8-hydroxyquinoline;

[0047] The leakage current inhibitor is selected from one or more of phosphotungstic acid, molybdic tungstic acid, 3,5-dihydroxybenzoic acid, and strontium nitrate.

[0048] In a preferred embodiment, the waterproofing agent is added at a mass percentage of 0.05-5.00% of the total electrolyte, preferably 0.10-3.00%.

[0049] In a preferred embodiment, the amount of hydrogen scavenger added, by mass percentage, is 0.10-15.00% of the total electrolyte, preferably 0.20-4.00%.

[0050] In a preferred embodiment, the flashover enhancer is added at a mass percentage of 0.20-15.00% of the total electrolyte, preferably 0.50-10.00%.

[0051] In a preferred embodiment, the amount of the anti-corrosion additive added is 0.01-5.00% of the total electrolyte by mass percentage, preferably 0.01-1.00%.

[0052] As a preferred embodiment, the leakage current inhibitor is added at a mass percentage of 0.01-5.00% of the total electrolyte, preferably 0.01-1.00%.

[0053] In a preferred embodiment, the electrolyte further includes other organic carboxylic acids or their ammonium salts besides the cyclic olefin carboxylic acid ammonium salt compound;

[0054] Other organic carboxylic acids or their ammonium salts are selected from one or more of the following: sebacic acid, azelaic acid, benzoic acid, adipic acid, sebacic acid, dodecanoic acid, 1,6-dodecanoic acid, 1,7-sebacic acid and the ammonium salts of the above acids, preferably in an amount of 1.00-20.00% of the total electrolyte.

[0055] This embodiment also provides an aluminum electrolytic capacitor using the electrolyte for aluminum electrolytic capacitors described above.

[0056] The beneficial effects of using the electrolyte of the present invention will be further described below through several examples and comparative examples.

[0057] Example 1:

[0058] Thermal stability test of olefin carboxylic acid ammonium salt compounds at 105℃

[0059] The preparation method involves dissolving the compound involved in formula (1) or formula (2) in ethylene glycol to prepare a 5% ethylene glycol solution, sealing it in a stainless steel bottle, and observing the changes in various parameters after maintaining the temperature at 105°C for a period of time. The specific details are shown in the table below:

[0060] Table 1. Changes in conductivity after isothermal treatment at 105℃

[0061]

[0062]

[0063] From the above data, it can be concluded that the conductivity change of the compound involved in formula (1) or formula (2) in this embodiment after being kept at 105℃ for a period of time is about -53%, while that of ammonium sebacate is about -74% and that of ammonium 2-hexyl adipate is about -46%. The results show that the stability of the compound involved in formula (1) or formula (2) is better than that of ammonium sebacate but worse than that of ammonium 2-hexyl adipate.

[0064] Example 2:

[0065] Thermal stability tests of olefin ammonium carboxylate compounds and combinations of olefin ammonium carboxylate compounds with inorganic boron compounds at 125℃

[0066] 1. Preparation method of stock solution: Dissolve the compound involved in formula (1) or formula (2) in ethylene glycol to prepare a 5% ethylene glycol solution, and seal it in a stainless steel bottle;

[0067] 2. Preparation method of stock solution + 3% ammonium pentaborate: Dissolve the compound involved in formula (1) or formula (2) in this embodiment with ammonium pentaborate in ethylene glycol to prepare a 5% concentration cyclic olefin carboxylic acid ammonium salt + 3% ammonium pentaborate ethylene glycol solution, and seal it in a stainless steel bottle;

[0068] 3. The changes in various parameters of the electrolyte prepared by methods 1 and 2 above when kept at 125℃ for a period of time are shown in the table below:

[0069] Table 2.1 Changes in conductivity after isothermal treatment at 2125℃ (comparison of change rates over 2000 h and 0 h).

[0070]

[0071]

[0072] From the above data and phenomena, it can be concluded that the conductivity of the original solution of the compound involved in formula (1) or formula (2) in this embodiment changes by about -76% after being kept at 125°C for a period of time, while the conductivity changes by about -17% after adding a certain amount of ammonium pentaborate, which is a very significant improvement.

[0073] Example 3:

[0074] Prepare electrolyte and conduct capacitor test experiments.

[0075] High-voltage electrolyte was prepared according to the proportions in Tables 3 and 4, and the basic indicators were tested as shown in Table 5. Finally, capacitors were prepared and their capacitance, leakage current, loss, and ESR were tested as shown in Table 6.

[0076] Table 3. Composition ratio of electrolyte in each embodiment and comparative example

[0077]

[0078] Table 4. Amounts of each component added in the electrolytes of each embodiment and comparative example.

[0079]

[0080]

[0081] Table 5 Basic Parameters of Electrolyte

[0082] electrolyte Conductivity / mS / cm pH Moisture / % Room temperature flash fire / V 85℃ flashover voltage / V Example 1 1.241 6.15 2.55 559 517 Example 2 1.236 6.17 2.68 563 520 Example 3 1.227 6.18 2.69 568 522 Example 4 1.229 6.20 3.25 549 509 Example 5 1.237 6.22 2.99 564 514 Example 6 1.231 6.19 2.65 562 510 Example 7 1.227 6.21 2.75 560 517 Comparative Example 1 1.257 6.87 1.56 548 499 Comparative Example 2 1.232 6.89 1.65 552 509

[0083] 500V Electrolyte and Device Performance-Lifetime Test Results

[0084] The electrolytes from Examples 1 to 7, and Comparative Examples 1 and 2, were used to fabricate capacitors with specifications of 500V 470 35x50mm and a positive electrode foil of 700VF 0.47μF / cm². 2 The negative electrode foil is 2VF, the electrolytic paper is domestic WD270-40+W180-30, and the cover plate is 33.8*3.0PP film.

[0085] The performance and lifespan of its 500V electrolyte and devices were tested, and the test results are shown in Table 6.

[0086] Table 6 Results of ripple load life test at 125℃

[0087]

[0088]

[0089] As shown in Table 6, after the electrolytes in Examples 1 to 7 were used to make capacitors, the basic parameters of capacitance, leakage current, loss and ESR showed little change after a long-term ripple load life test. Compared with Comparative Examples 1 and 2 without inorganic borate electrolyte, they had higher stability. They passed the 125℃ ripple life test for 1000h. After the life test, the capacitors were dissected and no abnormalities such as corrosion, breakdown or hydration were found. In contrast, the parameters of the comparative examples without inorganic boron compounds changed greatly and exceeded the qualified range.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An electrolyte for a medium-high voltage aluminum electrolytic capacitor, characterized by comprising The mixture includes a solute, a solvent, and an additive, wherein the solute comprises a cyclic olefin carboxylic acid ammonium salt compound, and the additive comprises an inorganic boron compound, wherein the structural formula of the cyclic olefin carboxylic acid ammonium salt compound is shown in formula (1): （1）； Where A is a hydrogen atom or a group consisting of a hydrocarbon group, a carboxyl group, or an ammonium carboxylate group containing 1-10 carbon atoms; where B is a hydrogen atom or a hydrocarbon group containing 1-10 carbon atoms; x and y are integers, and the value of x+y is 0-30; The inorganic boron compound is selected from one or more of boric acid, ammonium diborate, ammonium pentaborate, and borate esters.

2. The electrolyte for medium- and high-voltage aluminum electrolytic capacitors according to claim 1, characterized in that, The cycloolefin carboxylate ammonium salt compound is selected from one of the following: 4-hexyl-6-carboxylammono-cyclohex-2-en-1-octanoic acid ammonium, 4-hexyl-5,6-dicarboxammono-6-methyl-cyclohex-2-en-1-octanoic acid ammonium, 4-hexyl-6-carboxammono-6-methyl-cyclohex-2-en-1-octanoic acid ammonium, 6-propyl-1,3,5-tricarboxammono-cyclohex-2-ene, 4-hexyl-5-ethyl-6-carboxammono-cyclohex-2-en-1-octanoic acid ammonium, and 4-hexyl-5-butyl-6-carboxammono-cyclohex-2-en-1-octanoic acid ammonium.

3. The electrolyte for medium-high voltage aluminum electrolytic capacitors according to claim 1, characterized in that, The amount of the cyclic olefin carboxylate ammonium salt compound added accounts for 0.10-30.0% of the total electrolyte by mass percentage; The inorganic boron compound is added in an amount of 1.00-10.00% of the total electrolyte.

4. The electrolyte for medium-high voltage aluminum electrolytic capacitors according to claim 3, characterized in that, The amount of the cyclic olefin carboxylate ammonium salt compound added accounts for 0.50-15.00% of the total electrolyte by mass percentage; The inorganic boron compound is added in an amount of 2.00-5.00% of the total electrolyte.

5. The electrolyte for medium-high voltage aluminum electrolytic capacitors according to claim 1, wherein The solvent accounts for 60.00-95.00% of the total electrolyte by mass percentage, and the solvent is selected from one or more of alcohols, alcohol ethers, amides, sulfones, sulfoxides and esters.

6. The electrolyte for medium-high voltage aluminum electrolytic capacitors according to claim 1, wherein The solvent is ethylene glycol or γ-butyrolactone.

7. The electrolyte for medium- and high-voltage aluminum electrolytic capacitors according to claim 1, characterized in that, The additives also include one or more of the following: waterproofing agents, hydrogen scavengers, flashover enhancers, anti-corrosion additives, and leakage current inhibitors.

8. The electrolyte for medium- and high-voltage aluminum electrolytic capacitors according to claim 7, characterized in that, The waterproofing agent is selected from one or more of hypophosphite, phosphorous acid, phosphoric acid and monoalkyl phosphate, or from one or more of ammonium or amine salts of hypophosphite, phosphorous acid, phosphoric acid and monoalkyl phosphate; The hydrogen scavenger is selected from one or more of p-nitrophenol, p-nitrobenzyl alcohol, o-nitroanisole, and m-nitroacetylbenzene; The flashover enhancer is selected from one or more of silica molten material, polyvinyl alcohol, polyethylene glycol, polyvinyl borate, polyvinyl phosphate, polyvinylpyrrolidone, and mannitol; The corrosion-resistant additive is selected from one or more of nitric acid, EDTA, silver benzoate, and 8-hydroxyquinoline; The leakage current inhibitor is selected from one or more of phosphotungstic acid, molybdic tungstic acid, 3,5-dihydroxybenzoic acid, and strontium nitrate.

9. The electrolyte for medium- and high-voltage aluminum electrolytic capacitors according to claim 8, characterized in that, The waterproofing agent is added at a rate of 0.05-5.00% of the total electrolyte by weight. The amount of hydrogen scavenging agent added, by mass percentage, is 0.10-15.00% of the total electrolyte. The flashover enhancer is added at a rate of 0.20-15.00% of the total electrolyte by mass percentage. The amount of the anti-corrosion additive added, by weight percentage, is 0.01-5.00% of the total electrolyte. The leakage current inhibitor is added at a rate of 0.01-5.00% of the total electrolyte by mass percentage.

10. The electrolyte for medium-high voltage aluminum electrolytic capacitors according to claim 1, wherein The electrolyte also includes other organic carboxylic acids or their ammonium salts besides the cyclic olefin carboxylic acid ammonium salt compound; Other organic carboxylic acids or their ammonium salts are selected from one or more of sebacic acid, azelaic acid, benzoic acid, adipic acid, dodecadic acid, and the ammonium salts of the above acids.

11. The electrolyte for a medium-high voltage aluminum electrolytic capacitor according to claim 10, wherein Other organic carboxylic acids or their ammonium salts are selected from one or more of the ammonium salts of 1,6-dodecanoic acid, 1,7-sebacic acid and the above acids.

12. The electrolyte for medium-high voltage aluminum electrolytic capacitors according to claim 10, wherein The amount of other organic carboxylic acids or their ammonium salts added accounts for 1.00-20.00% of the total electrolyte.

13. A medium-high voltage aluminum electrolytic capacitor, characterized by, Use the electrolyte for aluminum electrolytic capacitors as described in any one of claims 1-12.

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