Aluminum electrolytic capacitor electrolyte and preparation method thereof

Abstract

The present invention relates to the field of electrolyte technology, and discloses an aluminum electrolytic capacitor electrolyte and a preparation method thereof. The aluminum electrolytic capacitor electrolyte of the present invention comprises the following raw materials in percentage by weight: 65wt%-72wt% solvent, 20wt%-33wt% solute, and 3wt%-6wt% additive. A modified carboxylate ammonium salt is introduced as the solute, and a modified polyvinyl alcohol is introduced as the additive as a flash voltage enhancer. The synergistic effect improves the flash voltage and conductivity of the electrolyte, thereby extending the service life of the aluminum electrolytic capacitor.

Description

Technical Field

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

[0002] Aluminum electrolytic capacitors currently hold a significant market share. They boast high capacitance per unit volume, compact size, light weight, low price, and self-healing capabilities, making them widely used in electronic toys, home appliances, switch lighting, communications equipment, and consumer electronics. The electrolyte, serving as the actual cathode in electrolytic capacitors, plays a crucial role in improving their overall performance.

[0003] The electrolyte primarily consists of three components: solvent, organic solute, and additives. The solvent serves as a carrier for dissolving the organic solute and additives. The organic solute, the core component of the electrolyte, repairs defects in the aluminum anode foil oxide film and improves the electrolyte's conductivity. Additives are a general term for substances that enhance electrolyte performance, primarily including flash voltage enhancers, hydrogen absorbers, corrosion inhibitors, and waterproofing agents. However, some components of existing electrolytes have drawbacks. For example, the organic solutes, primarily linear ammonium carboxylates, have poor solubility in solvents and poor high-temperature stability. Flash voltage enhancers (such as polyvinyl alcohol) have limited impact on electrolyte conductivity and lightning voltage. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides an aluminum electrolytic capacitor electrolyte and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] An aluminum electrolytic capacitor electrolyte comprises the following raw materials in percentage by weight: 65 wt% to 72 wt% of a solvent, 20 wt% to 33 wt% of a solute, and 3 wt% to 6 wt% of an additive;

[0007] The solvent includes ethylene glycol and propylene glycol;

[0008] Furthermore, the solvent contains 40wt%-60wt% ethylene glycol and 12wt%-25wt% propylene glycol;

[0009] The solutes include boric acid, ammonium sebacate and modified carboxylic acid ammonium salt;

[0010] Furthermore, the solute contains 1 wt%-2 wt% of boric acid, 6 wt%-10 wt% of modified carboxylic acid ammonium salt, and 16 wt%-25 wt% of ammonium sebacate;

[0011] Furthermore, the modified carboxylate ammonium salt is prepared by the following steps:

[0012] Step A1: Stir diethylenetriamine in water, add N,N'-methylenebisacrylamide, react at 55-65°C for 24 hours, rotary evaporate, precipitate, purify, and dry to obtain a hyperbranched precursor;

[0013] Furthermore, in step A1, the molar ratio of diethylenetriamine to N,N'-methylenebisacrylamide is 2-2.03:1;

[0014] Step A2: Under nitrogen, the hyperbranched precursor is mixed and stirred in N,N-dimethylformamide, succinic acid and concentrated sulfuric acid are added, and the mixture is heated to 120-140° C. for 4-6 hours. Ammonia gas is then introduced to adjust the pH to 6-7, and the mixture is distilled under reduced pressure and dried to obtain a modified carboxylic acid ammonium salt;

[0015] Further, in step A2, the molar ratio of the hyperbranched precursor to succinic acid is 1:4-4.05;

[0016] Furthermore, in step A2, the amount of concentrated sulfuric acid is 0.005-0.01 wt % of the total amount of reactants.

[0017] The additives include 1wt%-4wt% of a flash voltage enhancer, 0.5wt%-1.5wt% of a waterproofing agent, and 0.3wt%-0.6wt% of a hydrogen remover.

[0018] Furthermore, the flash voltage enhancer is modified polyvinyl alcohol, the waterproofing agent is ammonium dihydrogen phosphate, and the hydrogen remover is a nitro compound containing a benzene ring;

[0019] Furthermore, the nitro compound containing a benzene ring is one of p-nitrobenzoic acid, p-nitrophenol and p-nitrobenzyl alcohol;

[0020] Furthermore, the modified polyvinyl alcohol is prepared by the following steps:

[0021] Step B1, p-nitrobenzoyl chloride and tetrahydrofuran were stirred evenly in an ice-water bath, imidazole and triethylamine were added and stirred for 30 minutes, then the temperature was raised to 40°C and stirred for 3.5-4.5 hours, filtered, rotary evaporated, and then Pd / C and ethanol were added and stirred for 20 minutes, and then hydrazine hydrate was added and refluxed at 75°C for 5-7 hours, filtered, washed, and dried to obtain an imidazole derivative;

[0022] Furthermore, in step B1, the ratio of p-nitrobenzoyl chloride, tetrahydrofuran, imidazole, triethylamine, Pd / C, ethanol and hydrazine hydrate is 0.01-0.012 mol:50 mL:0.01 mol:0.012 mol:0.01-0.02 g:50 mL:2-3 g;

[0023] Step B2: Stir polyvinyl alcohol (PVA0588) and water at 80°C for 30 minutes, adjust the pH of the system to 10.8-11.2, slowly add epichlorohydrin while maintaining the pH of the system constant, and maintain the temperature for 1-2 hours to obtain epoxidized polyvinyl alcohol;

[0024] Furthermore, in step B2, the mass ratio of polyvinyl alcohol, water and epichlorohydrin is 10-15:100:0.5-2;

[0025] Furthermore, the pH of the system in step B2 is adjusted by a 20 wt % potassium hydroxide solution;

[0026] Step B3, adding an imidazole derivative to the epoxidized polyvinyl alcohol described in step B2, heating to 35° C. and stirring for 2-4 hours, adding anhydrous ethanol and stirring for 30 minutes, filtering, and drying to obtain modified polyvinyl alcohol;

[0027] Furthermore, in step B3, the molar ratio of the imidazole derivative to the epichlorohydrin in step B2 is 1:1, and the mass of anhydrous ethanol is twice that of the epoxidized polyvinyl alcohol.

[0028] A method for preparing an electrolyte for an aluminum electrolytic capacitor comprises the following steps:

[0029] Weigh the raw materials according to mass percentage, stir the solvent at 70-90°C, add the solute, heat to 110-120°C and stir for 25-45 minutes, cool to 60-80°C, add the additives and stir evenly to obtain the electrolyte for aluminum electrolytic capacitors.

[0030] Beneficial effects of the present invention:

[0031] The electrolyte of the present invention introduces modified carboxylic acid ammonium salt into the solute, and introduces modified polyvinyl alcohol into the additive as a flash voltage enhancer, thereby comprehensively enhancing the flash voltage and conductivity of the electrolyte, thereby enhancing the service life of the aluminum electrolytic capacitor.

[0032] The modified carboxylic acid ammonium salt in the present application has a branched molecular structure. The ammonium salt structure at the end of the molecule can synergistically act with the amide group to enhance the dissociation ability of the solvent, increase the effective ion concentration, significantly enhance the ion migration ability of the electrolyte, reduce the resistance and increase the conductivity, thereby reducing the internal resistance of the capacitor and improving the performance and stability of the capacitor. The amide structure in the molecular chain can utilize the N atoms and O atoms to react with the Al2O3 atoms in the defects of the anodic oxide film. 3+ The structure also has strong adsorption and can be adsorbed on the surface of aluminum foil to form a passivation layer, reducing the direct contact between the electrolyte and the aluminum substrate, and consuming free H +, reducing the risk of H2 precipitation. At the same time, the amide structure has a higher bond energy and better heat resistance, which can prolong the decomposition and volatilization of the electrolyte at high temperature and extend the service life of the capacitor.

[0033] Modified polyvinyl alcohol is added to the electrolyte of the present application as a flash voltage enhancer, which significantly improves the flash voltage of the electrolyte. This is because the imidazole structure introduced in the modified polyvinyl alcohol can be adsorbed on the surface of the anode foil to fill defects, forming a denser and more stable anode passivation film, reducing the breakdown caused by local electric field concentration, and the rigid structure of the benzene ring structure is also adsorbed on the surface of the aluminum foil to form a physical barrier, inhibiting the local corrosion and electrochemical corrosion of the oxide film by the electrolyte, thereby improving the service life of the aluminum electrolytic capacitor. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0035] Example 1: Modified carboxylic acid ammonium salt is prepared by the following steps:

[0036] Step A1: 2 mol of diethylenetriamine was stirred uniformly in water, 1 mol of N,N'-methylenebisacrylamide was added, and the mixture was reacted at 55°C for 24 hours. The mixture was rotary evaporated, precipitated, purified, and dried to obtain a hyperbranched precursor.

[0037] Step A2: Under nitrogen conditions, 1 mol of the hyperbranched precursor was mixed and stirred in N,N-dimethylformamide, 4 mol of succinic acid and concentrated sulfuric acid were added, and the mixture was heated to 120°C for 4 hours. Ammonia was then introduced to adjust the pH to 6, and the mixture was distilled under reduced pressure and dried to obtain a modified carboxylic acid ammonium salt. The concentrated sulfuric acid accounted for 0.005 wt% of the total amount of the reactants.

[0038] Modified polyvinyl alcohol is prepared by the following steps:

[0039] Step B1, 0.01 mol of p-nitrobenzoyl chloride and 50 mL of tetrahydrofuran were stirred in an ice-water bath, 0.01 mol of imidazole and 0.012 mol of triethylamine were added and stirred for 30 min, then the temperature was raised to 40 ° C and stirred for 3.5 h, filtered, and rotary evaporated, 0.01 g of Pd / C and 50 mL of ethanol were added and stirred for 20 min, and then 2 g of hydrazine hydrate was added and refluxed at 75 ° C for 5 h, filtered, washed, and dried to obtain an imidazole derivative;

[0040] Step B2: 10 g of polyvinyl alcohol (PVA0588) and 100 g of water were stirred at 80° C. for 30 min, the pH of the system was adjusted to 10.8, and 0.5 g of epichlorohydrin was slowly added while maintaining the pH of the system constant. The temperature was maintained for 1 h to obtain epoxidized polyvinyl alcohol. The pH of the above system was adjusted with a 20 wt % potassium hydroxide solution.

[0041] Step B3: add an imidazole derivative to the epoxidized polyvinyl alcohol described in step B2, raise the temperature to 35°C and stir for 2h, add anhydrous ethanol and stir for 30min, filter and dry to obtain modified polyvinyl alcohol, the molar ratio of the imidazole derivative and the epichlorohydrin in step B2 is 1:1, and the mass of anhydrous ethanol is twice that of the epoxidized polyvinyl alcohol.

[0042] Example 2: Modified carboxylic acid ammonium salt is prepared by the following steps:

[0043] Step A1: 2.01 mol of diethylenetriamine was stirred uniformly in water, 1 mol of N,N'-methylenebisacrylamide was added, and the mixture was reacted at 60°C for 24 hours. The mixture was rotary evaporated, precipitated, purified, and dried to obtain a hyperbranched precursor;

[0044] Step A2: Under nitrogen conditions, 1 mol of the hyperbranched precursor was mixed and stirred in N,N-dimethylformamide, 4.02 mol of succinic acid and concentrated sulfuric acid were added, and the mixture was heated to 130°C for 5 hours. Ammonia was then introduced to adjust the pH to 6.5, and the mixture was distilled under reduced pressure and dried to obtain a modified carboxylic acid ammonium salt. The concentrated sulfuric acid accounted for 0.0075 wt% of the total amount of the reactants.

[0045] Modified polyvinyl alcohol is prepared by the following steps:

[0046] Step B1, 0.011 mol of p-nitrobenzoyl chloride and 50 mL of tetrahydrofuran were stirred in an ice-water bath, 0.01 mol of imidazole and 0.012 mol of triethylamine were added and stirred for 30 min, then the temperature was raised to 40 ° C and stirred for 4 h, filtered, and rotary evaporated, 0.015 g of Pd / C and 50 mL of ethanol were added and stirred for 20 min, and then 2.5 g of hydrazine hydrate was added and refluxed at 75 ° C for 6 h, filtered, washed, and dried to obtain an imidazole derivative;

[0047] Step B2: 12.5 g of polyvinyl alcohol (PVA0588) and 100 g of water were stirred at 80° C. for 30 min, the pH of the system was adjusted to 11, and 1 g of epichlorohydrin was slowly added while maintaining the pH of the system constant. The temperature was maintained for reaction for 1.5 h to obtain epoxidized polyvinyl alcohol. The pH of the above system was adjusted with a 20 wt % potassium hydroxide solution.

[0048] Step B3: add an imidazole derivative to the epoxidized polyvinyl alcohol described in step B2, raise the temperature to 35°C and stir for 3h, add anhydrous ethanol and stir for 30min, filter and dry to obtain modified polyvinyl alcohol, the molar ratio of the imidazole derivative and the epichlorohydrin in step B2 is 1:1, and the mass of anhydrous ethanol is twice that of the epoxidized polyvinyl alcohol.

[0049] Example 3: Modified carboxylic acid ammonium salt is prepared by the following steps:

[0050] Step A1: 2.03 mol of diethylenetriamine was stirred uniformly in water, 1 mol of N,N'-methylenebisacrylamide was added, and the mixture was reacted at 65°C for 24 hours. The mixture was rotary evaporated, precipitated, purified, and dried to obtain a hyperbranched precursor;

[0051] Step A2: Under nitrogen conditions, 1 mol of the hyperbranched precursor was mixed and stirred in N,N-dimethylformamide, 4.05 mol of succinic acid and concentrated sulfuric acid were added, and the mixture was heated to 140°C for 6 hours. Ammonia was then introduced to adjust the pH to 7, and the mixture was distilled under reduced pressure and dried to obtain a modified carboxylic acid ammonium salt. The concentrated sulfuric acid accounted for 0.01 wt% of the total amount of the reactants.

[0052] Modified polyvinyl alcohol is prepared by the following steps:

[0053] Step B1, 0.012 mol of p-nitrobenzoyl chloride and 50 mL of tetrahydrofuran were stirred in an ice-water bath, 0.01 mol of imidazole and 0.012 mol of triethylamine were added and stirred for 30 min, then the temperature was raised to 40 ° C and stirred for 4.5 h, filtered, and rotary evaporated, 0.02 g of Pd / C and 50 mL of ethanol were added and stirred for 20 min, and then 3 g of hydrazine hydrate was added and refluxed at 75 ° C for 7 h, filtered, washed, and dried to obtain an imidazole derivative;

[0054] Step B2: 15 g of polyvinyl alcohol (PVA0588) and 100 g of water were stirred at 80° C. for 30 min, the pH of the system was adjusted to 11.2, and 2 g of epichlorohydrin was slowly added while maintaining the pH of the system constant. The temperature was maintained for 2 h to obtain epoxidized polyvinyl alcohol. The pH of the above system was adjusted with a 20 wt % potassium hydroxide solution.

[0055] Step B3: add an imidazole derivative to the epoxidized polyvinyl alcohol described in step B2, raise the temperature to 35°C and stir for 4 hours, add anhydrous ethanol and stir for 30 minutes, filter and dry to obtain modified polyvinyl alcohol, the molar ratio of the imidazole derivative and the epichlorohydrin in step B2 is 1:1, and the mass of anhydrous ethanol is twice that of the epoxidized polyvinyl alcohol.

[0056] Example 4: A method for preparing an electrolyte for an aluminum electrolytic capacitor comprises the following steps:

[0057] The raw materials were weighed according to mass percentage, 60 wt % of ethylene glycol and 12 wt % of propylene glycol were stirred uniformly at 70 ° C, 1 wt % of boric acid, 6 wt % of the modified carboxylate ammonium salt prepared in Example 1, and 18 wt % of ammonium sebacate were added, and the temperature was raised to 110 ° C and stirred for 25 min. The mixture was cooled to 60 ° C, and 2 wt % of the modified polyvinyl alcohol prepared in Example 1, 0.7 wt % of ammonium dihydrogen phosphate, and 0.3 wt % of p-nitrobenzoic acid were added and stirred uniformly to obtain an aluminum electrolytic capacitor electrolyte.

[0058] Example 5: A method for preparing an electrolyte for an aluminum electrolytic capacitor comprises the following steps:

[0059] The raw materials were weighed by mass percentage, 50 wt% of ethylene glycol and 18 wt% of propylene glycol were stirred uniformly at 80 ° C, 1.5 wt% of boric acid, 8 wt% of the modified carboxylate ammonium salt prepared in Example 2, and 18 wt% of ammonium sebacate were added, and the temperature was raised to 115 ° C and stirred for 35 minutes. The mixture was cooled to 70 ° C, and 3 wt% of the modified polyvinyl alcohol prepared in Example 2, 1 wt% of ammonium dihydrogen phosphate, and 0.5 wt% of p-nitrophenol were added and stirred uniformly to obtain an aluminum electrolytic capacitor electrolyte.

[0060] Example 6: A method for preparing an electrolyte for an aluminum electrolytic capacitor comprises the following steps:

[0061] The raw materials were weighed according to mass percentage, 40 wt% of ethylene glycol and 25 wt% of propylene glycol were stirred uniformly at 90 ° C, 2 wt% of boric acid, 10 wt% of the modified carboxylate ammonium salt prepared in Example 3, and 18 wt% of ammonium sebacate were added, and the temperature was raised to 120 ° C and stirred for 45 minutes. The mixture was cooled to 80 ° C, and 3.5 wt% of the modified polyvinyl alcohol prepared in Example 3, 1.2 wt% of ammonium dihydrogen phosphate, and 0.3 wt% of p-nitrobenzyl alcohol were added and stirred uniformly to obtain an aluminum electrolytic capacitor electrolyte.

[0062] Comparative Example 1: This comparative example is an electrolyte for aluminum electrolytic capacitors. The difference from Example 6 is that dodecanedioic acid ammonium is used instead of the modified carboxylate ammonium salt prepared in Example 3, and all other aspects are the same.

[0063] Comparative Example 2: This comparative example is an electrolyte for aluminum electrolytic capacitors. The difference from Example 6 is that polyvinyl alcohol is used instead of the modified polyvinyl alcohol prepared in Example 3, and the rest are the same.

[0064] Comparative Example 3: This comparative example is an electrolyte for aluminum electrolytic capacitors. The difference from Example 6 is that dodecanedioic acid ammonium is used instead of the modified carboxylate ammonium salt prepared in Example 3, and polyvinyl alcohol is used instead of the modified polyvinyl alcohol prepared in Example 3. The rest are the same.

[0065] Performance testing:

[0066] Flash voltage test: The electrolytes prepared in Examples 4-6 and Comparative Examples 1-3 were used to prepare aluminum electrolytic capacitor cores (comprising an anode foil, electrolytic paper soaked in electrolyte, a cathode foil, and electrolytic paper soaked in electrolyte). The cores were then immersed in the electrolyte to obtain impregnated cores. The cores were electrophoresed at 10 mA / cm 2 The current density is increased at a constant current until the first flash occurs on the anode foil, or when the voltmeter or ammeter in the electrophoresis instrument fluctuates greatly, the voltage corresponding to the value is the flash voltage of the electrolyte;

[0067] Conductivity Test: 20 ml of each electrolyte prepared in Examples 4-6 and Comparative Examples 1-3 was placed in a beaker. According to NB / T42006-2013 "Test Methods for Electrolytes for All-Vanadium Redox Flow Batteries," the beakers containing the test solutions were placed in a constant-temperature water bath at 25°C to maintain a constant temperature. The conductivity of the working test solutions was measured using a conductivity meter. Three measurements were performed for each Example and Comparative Example, and the average of the three readings was used as the measurement result.

[0068] The test results are shown in Table 1:

[0069] Table 1: Performance test results

[0070]

[0071] As can be seen from Table 1, the electrolyte for aluminum electrolytic capacitors prepared in the present invention has high electrical conductivity and flash voltage, and can be used in aluminum electrolytic capacitors to increase the service life of the capacitors.

[0072] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the scope defined by the concept of the invention, they should all fall within the scope of protection of the present invention.

Claims

1. An electrolyte for an aluminum electrolytic capacitor, characterized in that: The raw materials include the following weight percentages: 65wt%-72wt% solvent, 20wt%-33wt% solute, and 3wt%-6wt% additives; The solvent includes 40wt%-60wt% ethylene glycol and 12wt%-25wt% propylene glycol; The solute includes 1wt%-2wt% of boric acid, 6wt%-10wt% of modified carboxylic acid ammonium salt and 16wt%-25wt% of ammonium sebacate; The additives include 1wt%-4wt% of a flash voltage enhancer, 0.5wt%-1.5wt% of a waterproofing mixture, and 0.3wt%-0.6wt% of a hydrogen remover; The modified carboxylic acid ammonium salt is prepared by reacting a hyperbranched precursor with succinic acid and then introducing ammonia gas, and the hyperbranched precursor is prepared by reacting diethylenetriamine with N,N'-methylenebisacrylamide; The flash voltage enhancer is modified polyvinyl alcohol, the waterproofing agent is ammonium dihydrogen phosphate, and the hydrogen remover is a nitro compound containing a benzene ring; The modified polyvinyl alcohol is prepared by the following steps: Step B1, p-nitrobenzoyl chloride and tetrahydrofuran were stirred evenly in an ice-water bath, imidazole and triethylamine were added and stirred for 30 minutes, then the temperature was raised to 40°C and stirred for 3.5-4.5 hours, filtered, rotary evaporated, and then Pd / C and ethanol were added and stirred for 20 minutes, and then hydrazine hydrate was added and refluxed at 75°C for 5-7 hours, filtered, washed, and dried to obtain an imidazole derivative; Step B2, stirring polyvinyl alcohol and water at 80° C. for 30 minutes, adjusting the pH of the system to 10.8-11.2, slowly adding epichlorohydrin while maintaining the pH of the system unchanged, and maintaining the temperature for 1-2 hours to obtain epoxidized polyvinyl alcohol; Step B3: add an imidazole derivative to the epoxidized polyvinyl alcohol described in step B2, heat to 35° C. and stir for 2-4 hours, add anhydrous ethanol and stir for 30 minutes, filter and dry to obtain modified polyvinyl alcohol.

2. The electrolyte for aluminum electrolytic capacitors according to claim 1, wherein: The modified carboxylic acid ammonium salt is prepared by the following steps: Step A1: Stir diethylenetriamine in water, add N,N'-methylenebisacrylamide, react at 55-65°C for 24 hours, rotary evaporate, precipitate, purify, and dry to obtain a hyperbranched precursor; Step A2: Under nitrogen, the hyperbranched precursor is mixed and stirred in N,N-dimethylformamide, succinic acid and concentrated sulfuric acid are added, and the mixture is heated to 120-140°C for 4-6 hours. Ammonia is then introduced to adjust the pH to 6-7, and the mixture is distilled under reduced pressure and dried to obtain the modified carboxylic acid ammonium salt.

3. The electrolyte for aluminum electrolytic capacitors according to claim 2, characterized in that: In step A1, the molar ratio of diethylenetriamine to N,N'-methylenebisacrylamide is 2-2.03:

1.

4. The electrolyte for aluminum electrolytic capacitors according to claim 2, wherein: In step A2, the molar ratio of the hyperbranched precursor to succinic acid is 1:4-4.05, and the concentrated sulfuric acid is 0.005-0.01 wt % of the total amount of reactants.

5. The electrolyte for aluminum electrolytic capacitors according to claim 1, characterized in that: In step B1, the usage ratio of p-nitrobenzoyl chloride, tetrahydrofuran, imidazole, triethylamine, Pd / C, ethanol and hydrazine hydrate is 0.01-0.012 mol:50 mL:0.01 mol:0.012 mol:0.01-0.02 g:50 mL:2-3 g.

6. The electrolyte for aluminum electrolytic capacitors according to claim 1, characterized in that: In step B2, the mass ratio of polyvinyl alcohol, water and epichlorohydrin is 10-15:100:0.5-2, and the pH of the system is adjusted by 20 wt % potassium hydroxide solution.

7. The electrolyte for aluminum electrolytic capacitors according to claim 1, characterized in that: In step B3, the molar ratio of the imidazole derivative to the epichlorohydrin in step B2 is 1:1, and the mass of anhydrous ethanol is twice that of the epoxidized polyvinyl alcohol.

8. A method for preparing the electrolyte for aluminum electrolytic capacitors according to any one of claims 1 to 7, characterized in that: The following steps are involved: Weigh the raw materials according to mass percentage, stir the solvent at 70-90°C, add the solute, heat to 110-120°C and stir for 25-45 minutes, cool to 60-80°C, add the additives and stir evenly to obtain the electrolyte for aluminum electrolytic capacitors.

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