Branched chain carboxylate composite type high-temperature-resistant aluminum electrolytic capacitor electrolyte and preparation method thereof
By using a branched carboxylate composite electrolyte, combined with a specific branched structure and functional additives, the problem of insufficient thermal stability and conductivity of traditional aluminum electrolytic capacitors at high temperatures has been solved, thereby improving the stability and safety of capacitors at high temperatures.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-03-27
AI Technical Summary
Traditional aluminum electrolytic capacitor electrolytes have poor thermal stability at high temperatures, rapid decrease in conductivity, weak film repair ability, and low flash voltage, which cannot meet the requirements for long-term stable operation in high-temperature environments.
A branched carboxylate composite electrolyte is used, which contains a main solute with a specific branched structure, an optimized combination of high-boiling-point and medium-viscosity solvents, and functional additives such as flashover inhibitors, film-forming promoters, corrosion inhibitors, and wetting agents. Through steric hindrance effect and synergistic effect, thermal stability, conductivity and flashover voltage are improved.
It significantly improves the high-temperature operating stability and safety of aluminum electrolytic capacitors, reduces high-temperature ESR, extends service life, and enhances the overall weather resistance and safety of capacitors.
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Figure CN121748173A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aluminum electrolytic capacitor processing technology, specifically to a branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte and its preparation method. Background Technology
[0002] With the rapid development of electronic technology, electronic devices are placing increasingly higher demands on the performance of aluminum electrolytic capacitors. This is particularly true in fields such as automotive electronics, industrial control, and new energy, which require capacitors to operate stably for extended periods in high-temperature environments. The electrolyte, as the "blood" of aluminum electrolytic capacitors, directly determines the capacitor's key performance indicators.
[0003] Traditional electrolytes often use ammonium salts or organic amine salts of straight-chain dicarboxylic acids (such as adipic acid and azelaic acid) as the main solute. These electrolytes perform reasonably well at room temperature or lower temperatures, but have significant drawbacks at high temperatures. 1. Poor thermal stability: It is prone to decomposition at high temperatures, producing gas that causes capacitors to bulge, and at the same time corrodes the oxide film of the anode foil, shortening its lifespan.
[0004] 2. Rapid decrease in conductivity: At high temperatures, solvents evaporate or decompose, reducing ion concentration and increasing viscosity, leading to a sharp increase in ESR and deterioration of filtering performance.
[0005] 3. Weak film-forming and repair capabilities: At high temperatures, it cannot effectively provide oxygen atoms to repair the oxide film (Al2O3) on the surface of the anode foil, resulting in increased leakage current and accelerated capacitor failure.
[0006] IV. Low flashover voltage: In high-voltage applications, the flashover voltage decreases at high temperatures, increasing safety risks.
[0007] To improve temperature resistance, the industry has tried a variety of methods: High-boiling-point solvents such as γ-butyrolactone (GBL) and sucrose formate can be used, but high-boiling-point solvents often have high viscosity, which affects low-temperature performance and may not fundamentally solve the problem of solute decomposition.
[0008] Adding heat stabilizers, such as phenols, amines, and phosphate esters, has limited effect.
[0009] Developing novel solutes: exploring carboxylates with better thermal and electrochemical stability. Some studies focus on aromatic carboxylates or highly branched carboxylates, but problems such as insufficient solubility, cost, or overall performance still exist.
[0010] Composite electrolyte system: Attempts have been made to combine solutes with different properties, but how to achieve synergistic effects and obtain excellent overall high-temperature performance remains a challenge.
[0011] Therefore, there is an urgent need to develop a new electrolyte system whose core solute should have excellent thermal stability, the ability to maintain high conductivity over a wide temperature range, and the ability to effectively promote oxide film repair at high temperatures, so as to meet the needs of next-generation high-reliability, long-life, wide-temperature-range aluminum electrolytic capacitors. To this end, a branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte and its preparation method are proposed. Summary of the Invention
[0012] The purpose of this invention is to provide a branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte and its preparation method, so as to solve the problems mentioned in the background art.
[0013] To achieve the above objectives, the present invention provides the following technical solution: a branched-chain carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte, composed of the following components by mass percentage: Main solute: 8%-15%, which includes: Branched-chain ammonium carboxylate salt A: 5%-10%, its general structural formula is (R¹)(R²)C(COO) - NH4 + , wherein R¹ and R² are independently selected from C1-C6 alkyl, hydroxyalkyl or combinations thereof, and at least one R contains a branched structure; Branched-chain ammonium carboxylate B: 3%-5%, with the general structural formula (R³)HC(COO) - NH4 + or (R³)(R) 4 )C(COO - NH4 + , where R³ and R 4 It is independently selected from C1-C4 alkyl groups, and the molecule has a β-branched structure; Solvent: 75%-85%, which includes: High-boiling-point non-aqueous solvents: 60%-70%; Medium-viscosity co-solvents: 15%-25%; Functional additives: 0.5%-5%, which include: Flashover inhibitor: 0.5%-2%, film-forming accelerator: 0.5%-1.5%, corrosion resistant agent: 0.5%-1.5%, wetting agent: 0.1%-1%.
[0014] Preferably, the above-mentioned branched ammonium carboxylate salt A is selected from one of trimethylammonium acetate, ammonium isobutyrate, and ammonium tert-valerate.
[0015] Preferably, the above-mentioned branched ammonium carboxylate B is selected from one of α-methylbutyrate ammonium.
[0016] Preferably, the high-boiling-point non-aqueous solvent is selected from one or a mixture of two of γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, propylene carbonate, and ethylene carbonate.
[0017] Preferably, the medium viscosity cosolvent is selected from ethylene glycol, diethylene glycol, polyethylene glycol monomethyl ether (Mn=250-400), and 1,4-butanediol.
[0018] Preferably, the above-mentioned flash fire inhibitor is selected from one of hexamethylphosphoric triamine, tetramethylurea, and 1,3-dimethyl-2-imidazolinone.
[0019] Preferably, the film-forming promoter is selected from one of catechol, resorcinol, hydroquinone, and pyrogallol.
[0020] Preferably, the corrosion resistant agent is selected from one of triphenyl phosphate, tributyl phosphate, and triphenyl phosphite.
[0021] Preferably, the wetting agent is selected from quaternary ammonium salt surfactants.
[0022] A method for preparing a branched-chain carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte includes the following steps: S1. Pretreatment: Add the required amount of high-boiling-point non-aqueous solvent and co-solvent to a dry reaction vessel, stir and heat to 50-60℃; S2. Solute dissolution: Under continuous stirring, slowly add branched ammonium carboxylate A and branched ammonium carboxylate B in sequence, control the temperature at 50-60℃, and stir for 1-2 hours until completely dissolved; S3. Additive addition: Cool the reaction solution to 30-40℃, and add the flash fire inhibitor, film-forming promoter, corrosion resistant agent and wetting agent in sequence. Stir for 15-30 minutes after each addition to dissolve and disperse them. S4. Deep dehydration: Heat the solution to 70-80℃ and dehydrate it under vacuum until the water content is ≤ 50 ppm; S5. Cooling and Filtration: Stop heating, stir and cool to room temperature, then filter through a microporous membrane with a pore size ≤ 0.22 μm; S6. Filling and storage: Fill and seal the electrolyte in a dry environment.
[0023] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects: 1. A branched ammonium carboxylate with a specific steric hindrance structure was used as the composite main solute. The steric hindrance effect brought by the branched structure greatly enhances the thermal stability of carboxylate anions and ammonium ions at high temperatures, suppressing their tendency to decompose under heat. This allows the upper limit of the operating temperature of aluminum electrolytic capacitors to be stably increased to above 135℃, giving the capacitors better high-temperature operating stability. Furthermore, the branched carboxylate can still maintain a high degree of dissociation and ion mobility at high temperatures. Combined with the optimized combination of high-boiling-point and medium-viscosity solvents, as well as the effective inhibition of ion pair association by HMPA, the electrolyte can still maintain a low viscosity and high conductivity at high temperatures, thereby significantly reducing the high-temperature ESR of the capacitor.
[0024] 2. By adding a highly efficient film-forming promoter, active oxygen atoms can be effectively released under high temperature and electric field conditions, promoting the dynamic repair of the alumina dielectric layer on the anode foil surface. This greatly reduces the leakage current of the capacitor at high temperatures, effectively extending the capacitor's service life. Furthermore, HMPA, as a strong hydrogen bond acceptor, can effectively "isolate" the anions and cations in the electrolyte, reducing the formation of ion pairs, increasing the concentration of free carriers, and forming a more effective protective layer at the electrode interface. This significantly improves the flashover voltage of the electrolyte system and enhances safety under high-voltage applications.
[0025] 3. The addition of corrosion resistant agents can form a protective adsorption film on the anode metal surface, inhibiting corrosion. The addition of wetting agents can significantly reduce the surface tension of the electrolyte, improve its wetting speed and penetration depth on the electrolytic paper and electrode foil, ensuring sufficient internal impregnation, which helps to reduce the initial ESR and improve product consistency. At the same time, these additives also help to improve the overall tolerance of the electrolyte to voltage and temperature fluctuations, and improve the overall weather resistance of the capacitor. The synergistic effect produced by the specific combination of branched carboxylates makes it perform better in terms of thermal stability and ionic conductivity than using any one component alone. Each additive plays a complementary role around the main solute, jointly constructing a highly efficient and stable high-temperature resistant electrolyte system, which can effectively improve the working stability of the capacitor. Attached Figure Description
[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation
[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0029] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce. Example 1
[0030] Please see Figure 1 This invention provides a technical solution: a branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte, composed of the following components by mass percentage: Main solute: 8%-15%, which includes: Branched-chain ammonium carboxylate salt A: 5%-10%, its general structural formula is (R¹)(R²)C(COO) - NH4 + , wherein R¹ and R² are independently selected from C1-C6 alkyl, hydroxyalkyl or combinations thereof, and at least one R contains a branched structure, wherein the branched ammonium carboxylate salt A is selected from one of trimethylammonium acetate, ammonium isobutyrate and ammonium tert-valerate, specifically: the branched ammonium carboxylate salt A is selected from trimethylammonium acetate; Branched-chain ammonium carboxylate B: 3%-5%, with the general structural formula (R³)HC(COO) - NH4 + or (R³)(R) 4 )C(COO - NH4 + , where R³ and R 4 The ammonium carboxylate salt B is independently selected from C1-C4 alkyl groups and has a β-branched structure. Specifically, the ammonium carboxylate salt B is selected from α-methylbutyrate ammonium. The ammonium carboxylate salt with a specific steric hindrance structure is used as the composite main solute. The steric hindrance effect brought by the branched structure greatly enhances the thermal stability of carboxylate anions and ammonium ions at high temperatures and inhibits their tendency to decompose under heat. This can stably increase the upper limit of the working temperature of aluminum electrolytic capacitors to above 135℃, giving the capacitors better high-temperature working stability. Solvent: 75%-85%, which includes: High-boiling-point non-aqueous solvent: 60%-70%, wherein the high-boiling-point non-aqueous solvent is selected from one or a mixture of two of γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, propylene carbonate, and ethylene carbonate. Specifically, the high-boiling-point non-aqueous solvent is selected from γ-butyrolactone. Medium viscosity cosolvent: 15%-25%, wherein the medium viscosity cosolvent is selected from one of ethylene glycol, diethylene glycol, polyethylene glycol monomethyl ether (Mn=250-400), and 1,4-butanediol. Specifically, ethylene glycol is selected as the medium viscosity cosolvent. Branched carboxylates can still maintain a high degree of dissociation and ion mobility at high temperatures. Combined with the optimized combination of high boiling point and medium viscosity solvent, and the effective inhibition of ion pair association by HMPA, the electrolyte can still maintain a low viscosity and high conductivity at high temperatures, thereby significantly reducing the high temperature ESR of the capacitor. Functional additives: 0.5%-5%, which include: Flashover inhibitor: 0.5%-2%, wherein the flashover inhibitor is selected from one of hexamethylphosphoric triamine, tetramethylurea, and 1,3-dimethyl-2-imidazolinone. Specifically, hexamethylphosphoric triamine is selected as the flashover inhibitor. Hexamethylphosphoric triamine acts as a strong hydrogen bond acceptor, which can effectively "isolate" the anions and cations in the electrolyte, reduce the formation of ion pairs, increase the concentration of free carriers, and form a more effective protective layer at the electrode interface, thereby significantly improving the flashover voltage of the electrolyte system and enhancing the safety under high voltage applications. Film-forming accelerator: 0.5%-1.5%, wherein the film-forming accelerator is selected from one of catechol, resorcinol, hydroquinone, and pyrogallol. Specifically, pyrogallol is selected as the film-forming accelerator. By adding a highly efficient film-forming accelerator, active oxygen atoms can be effectively released under high temperature and electric field, promoting the dynamic repair of the alumina dielectric layer on the anode foil surface, greatly reducing the leakage current of the capacitor at high temperature, and effectively extending the service life of the capacitor. Corrosion resistant agent: 0.5%-1.5%, wherein the corrosion resistant agent is selected from one of triphenyl phosphate, tributyl phosphate, and triphenyl phosphite. Specifically, triphenyl phosphate is selected as the corrosion resistant agent. By adding the corrosion resistant agent, a protective adsorption film can be formed on the surface of the anode metal to inhibit corrosion. Wetting agent: 0.1%-1%, wherein the wetting agent is selected from quaternary ammonium salt surfactants, specifically: hexadecyltrimethylammonium bromide is selected as the wetting agent. The addition of the wetting agent can significantly reduce the surface tension of the electrolyte, improve its wetting speed and penetration depth on the electrolytic paper and electrode foil, ensure sufficient internal impregnation, and help reduce the initial ESR and improve product consistency.
[0031] These additives also help improve the overall tolerance of the electrolyte to voltage and temperature fluctuations, and enhance the overall weather resistance of the capacitor. Through the synergistic effect of specific branched carboxylates, they outperform any single component in terms of thermal stability and ionic conductivity. Each additive plays a complementary role around the main solute, jointly constructing a highly efficient and stable high-temperature resistant electrolyte system, which can effectively improve the working stability of the capacitor.
[0032] The specific formulation is as follows: Trimethylacetate: 8.0%, α-methylbutyrate: 3.0%, γ-butyrolactone: 65.0%, Ethylene glycol: 20.0%, Hexamethylphosphoric triamine: 1.0%, pyrogallol: 1.0%. Triphenyl phosphate: 1.0%. Cetyltrimethylammonium bromide: 0.5%.
[0033] A method for preparing a branched-chain carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte includes the following steps: S1. Pretreatment: Add the required amount of high-boiling-point non-aqueous solvent and co-solvent to a dry reaction vessel, specifically add 65g of γ-butyrolactone and 20g of ethylene glycol, stir and heat to 55℃; S2. Solute dissolution: Under continuous stirring, slowly add 8.0g of trimethylammonium acetate and 3.0g of α-methylbutyrate in sequence, control the temperature at 55℃, and stir for 1.5 hours until completely dissolved; S3. Additive addition: Cool the reaction solution to 35°C, and add 1.0g hexamethylphosphoric acid triamine, 1.0g pyrogallol, 1.0g triphenyl phosphate, and 0.5g hexadecyltrimethylammonium bromide in sequence. Stir for 20 minutes after each addition to dissolve and disperse the additives. S4. Deep dehydration: Heat the solution to 75°C and dehydrate it under vacuum until the water content is ≤ 50 ppm; S5. Cooling and Filtration: Stop heating, stir and cool to room temperature (25°C), then filter through a microporous membrane with a pore size ≤ 0.22 μm. S6. Filling and storage: Fill and seal the electrolyte in a dry environment.
[0034] Performance testing (potted to a rated voltage of 400V, Φ10mm×20mm capacitor): Operating temperature range: -55℃ ~ +135℃ (passed 1000 hours of high temperature load life test at 135℃); ESR at 125℃ and 100kHz: initial value ≤ 80 mΩ; after 1000h of load at 135℃, ΔESR ≤ 150% (industry requirements typically require ≤200-300%). Leakage current (LC) at 135℃: ≤ 0.01 CV (μA) (CV unit: μF·V); Flashover voltage (room temperature): ≥ 1.5 times the rated voltage. Example 2
[0035] Unlike Example 1, the branched-chain carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte is composed of the following components by mass percentage, with specific formulations as follows: Ammonium isobutyrate: 8.0%, α-methylbutyrate: 3.0%, N,N-dimethylformamide: 65.0%, diethylene glycol: 20.0%, tetramethylurea: 1.0%, resorcinol: 1.0%, tributyl phosphate: 1.0%, cetyltrimethylammonium bromide: 0.5%.
[0036] A method for preparing a branched-chain carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte includes the following steps: S1. Pretreatment: Add the required amount of high-boiling-point non-aqueous solvent and co-solvent to a dry reaction vessel, specifically add 65g of N,N-dimethylformamide and 20g of diethylene glycol, stir and heat to 58℃; S2. Solute dissolution: Under continuous stirring, slowly add 8.0g ammonium isobutyrate and 3.0g ammonium α-methylbutyrate in sequence, control the temperature at 58℃, and stir for 1.2 hours until completely dissolved; S3. Additive addition: Cool the reaction solution to 35℃, and add 1.0g tetramethylurea, 1.0g resorcinol, 1.0g tributyl phosphate, and 0.5g hexadecyltrimethylammonium bromide in sequence. Stir for 25 minutes after each addition to dissolve and disperse the additives. S4. Deep dehydration: Heat the solution to 75°C and dehydrate it under vacuum until the water content is ≤ 50 ppm; S5. Cooling and Filtration: Stop heating, stir and cool to room temperature (25°C), then filter through a microporous membrane with a pore size ≤ 0.22 μm. S6. Filling and storage: Fill and seal the electrolyte in a dry environment.
[0037] Performance testing (potted to a rated voltage of 400V, Φ10mm×20mm capacitor): Operating temperature range: -55℃ ~ +133℃ (passed 1000 hours of high temperature load life test at 133℃); ESR at 125℃ and 100kHz: initial value ≤ 80 mΩ; after 1000h at 133℃ load, ΔESR ≤ 150% (industry requirements are typically ≤200-300%). Leakage current (LC) at 133℃: ≤ 0.01 CV (μA) (CV unit: μF·V); Flashover voltage (room temperature): ≥ 1.5 times the rated voltage. Example 3
[0038] The difference from Example 1 is that, except for replacing the branched carboxylate A+B (11.0%) with an equal amount of the straight-chain solute ammonium adipate (11.0%), the other components, proportions, and preparation methods are the same as in Example 1. Performance test results: Upper operating temperature limit: only 105℃ (lifespan is significantly shortened at 125℃); ESR at 125℃ and 100kHz: initial value approximately 120 mΩ; after 1000h under load at 105℃, ΔESR >300%; The leakage current at 125℃ is significantly higher than that in Example 1.
[0039] In summary, branched ammonium carboxylate salts with specific steric hindrance structures were used as the composite main solute. The steric hindrance effect brought by the branched structure greatly enhanced the thermal stability of carboxylate anions and ammonium ions at high temperatures, suppressing their tendency to decompose under heat. This allowed the upper limit of the operating temperature of aluminum electrolytic capacitors to be stably increased to above 135℃, giving the capacitors better high-temperature operating stability. Furthermore, the branched carboxylate salts maintained high dissociation and ion mobility at high temperatures. Combined with the optimized combination of high-boiling-point and medium-viscosity solvents, and the effective inhibition of ion pair association by HMPA, the electrolyte maintained low viscosity and high conductivity at high temperatures, thus significantly reducing the high-temperature ESR of the capacitors. The addition of highly efficient film-forming promoters effectively released active oxygen atoms under high temperature and electric field conditions, promoting the dynamic repair of the alumina dielectric layer on the anode foil surface, greatly reducing the leakage current of the capacitors at high temperatures, effectively extending the capacitor's service life, and further enhancing the performance of HMPA. As a strong hydrogen bond acceptor, it can effectively "isolate" cations and anions in the electrolyte, reduce the formation of ion pairs, increase the concentration of free carriers, and form a more effective protective layer at the electrode interface. This significantly improves the flash voltage of the electrolyte system and enhances safety under high-voltage applications. The addition of corrosion resistant agents can form a protective adsorption film on the anode metal surface to inhibit corrosion. The addition of wetting agents can significantly reduce the surface tension of the electrolyte, increase its wetting speed and penetration depth on the electrolytic paper and electrode foil, ensure sufficient internal impregnation, and help reduce initial ESR and improve product consistency. At the same time, these additives also help improve the overall tolerance of the electrolyte to voltage and temperature fluctuations and improve the overall weather resistance of the capacitor. The synergistic effect produced by the specific combination of branched carboxylate salts makes its performance in thermal stability and ionic conductivity superior to that of any single component. Each additive plays a complementary role around the main solute, jointly constructing a highly efficient and stable high-temperature resistant electrolyte system, which can effectively improve the working stability of the capacitor.
[0040] Those skilled in the art will understand that the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.
Claims
1. A branched-chain carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte, characterized in that, It consists of the following components by mass percentage: Main solute: 8%-15%, which includes: Branched-chain ammonium carboxylate salt A: 5%-10%, its general structural formula is (R¹)(R²)C(COO) - NH4 + , wherein R¹ and R² are independently selected from C1-C6 alkyl, hydroxyalkyl or combinations thereof, and at least one R contains a branched structure; Branched-chain ammonium carboxylate B: 3%-5%, with the general structural formula (R³)HC(COO) - NH4 + or (R³)(R) 4 )C(COO - NH4 + , where R³ and R 4 It is independently selected from C1-C4 alkyl groups, and the molecule has a β-branched structure; Solvent: 75%-85%, which includes: High-boiling-point non-aqueous solvents: 60%-70%; Medium-viscosity co-solvents: 15%-25%; Functional additives: 0.5%-5%, which include: Flashover inhibitor: 0.5%-2%, film-forming accelerator: 0.5%-1.5%, corrosion resistant agent: 0.5%-1.5%, wetting agent: 0.1%-1%.
2. The branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte according to claim 1, characterized in that, The branched ammonium carboxylate salt A is selected from one of trimethylammonium acetate, ammonium isobutyrate, and ammonium tert-valerate.
3. The branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte according to claim 2, characterized in that, The branched ammonium carboxylate B is selected from one of α-methylbutyrate ammonium salts.
4. The branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte according to claim 1, characterized in that, The high-boiling-point non-aqueous solvent is selected from one or a mixture of two of γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, propylene carbonate, and ethylene carbonate.
5. The branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte according to claim 4, characterized in that, The medium viscosity co-solvent is selected from one of ethylene glycol, diethylene glycol, polyethylene glycol monomethyl ether (Mn=250-400), and 1,4-butanediol.
6. The branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte according to claim 1, characterized in that, The flash fire inhibitor is selected from one of hexamethylphosphoric triamine, tetramethylurea, and 1,3-dimethyl-2-imidazolinone.
7. The branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte according to claim 6, characterized in that, The film-forming promoter is selected from one of catechol, resorcinol, hydroquinone, and pyrogallol.
8. The branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte according to claim 7, characterized in that, The corrosion resistant agent is selected from one of triphenyl phosphate, tributyl phosphate, and triphenyl phosphite.
9. The branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte according to claim 8, characterized in that, The wetting agent is selected from quaternary ammonium salt type surfactants.
10. The method for preparing the branched carboxylate composite high-temperature resistant aluminum electrolytic capacitor electrolyte according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Pretreatment: Add the required amount of high-boiling-point non-aqueous solvent and co-solvent to a dry reaction vessel, stir and heat to 50-60℃; S2. Solute dissolution: Under continuous stirring, slowly add branched ammonium carboxylate A and branched ammonium carboxylate B in sequence, control the temperature at 50-60℃, and stir for 1-2 hours until completely dissolved; S3. Additive addition: Cool the reaction solution to 30-40℃, and add the flash fire inhibitor, film-forming promoter, corrosion resistant agent and wetting agent in sequence. Stir for 15-30 minutes after each addition to dissolve and disperse them. S4. Deep dehydration: Heat the solution to 70-80℃ and dehydrate it under vacuum until the water content is ≤ 50 ppm; S5. Cooling and Filtration: Stop heating, stir and cool to room temperature, then filter through a microporous membrane with a pore size ≤ 0.22 μm; S6. Filling and storage: Fill and seal the electrolyte in a dry environment.