Electrolyte for solid-liquid hybrid electrolytic capacitor and electrolytic capacitor

Abstract

The invention discloses an electrolyte for a solid-liquid hybrid electrolytic capacitor and the electrolytic capacitor, and relates to the technical field of capacitors. The electrolyte for the solid-liquid mixed electrolytic capacitor provided by the invention at least comprises the following components: a liquid component: 40-50% of gamma-butyrolactone, 8-12% of N-methyl pyrrolidone, 2-5% of straight-chain ammonium carboxylate, 5-15% of branched-chain long-chain ammonium dicarboxylate, 1-2% of a silane coupling agent and 0.5-5% of an additive; the solid components comprise 10 to 20 percent of surface modified carboxylated PEDOT (poly (3, 4-ethylenedioxythiophene)) nanofiber and 1 to 4 percent of nano particles. The electrolyte for the solid-liquid hybrid electrolytic capacitor is high in conductivity, high in sparking voltage and good in high-temperature and low-temperature stability.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitors, and in particular to an electrolyte for a solid-liquid hybrid electrolytic capacitor and an electrolytic capacitor. Background Art

[0002] Aluminum electrolytic capacitors' strong applicability has led to their widespread use in numerous industries and fields, including electrical equipment, communications equipment, medical devices, electronic instruments, automotive equipment, entertainment equipment, aerospace, and more. With the development of national infrastructure and networking, aluminum electrolytic capacitors have also begun to expand into various new industries, creating more room for their development. The working electrolyte of aluminum electrolytic capacitors, as the actual negative electrode of aluminum electrolytic capacitors, plays a crucial role in the product, affecting the product's long-term normal operation and lifespan and optimizing the capacitor's electrical performance. With the increasing market demand for high-power, small-size electrical products (including power supplies), manufacturers of these products (including power supplies) are demanding smaller size and higher ripple current from aluminum electrolytic capacitor manufacturers. In response to this demand, only solid-liquid hybrid capacitors can meet the requirements for high ripple current, long life, and small size. Solid-liquid hybrid capacitors are solid-liquid hybrid electrolytic capacitors, combining the advantages of conventional liquid and solid electrolytic capacitors while offering greater flexibility in use than liquid capacitors. Although hybrid capacitors cannot provide voltage and capacity comparable to traditional electrolyte capacitors, they have the ability to generate and repair the oxide film dielectric layer on the surface of the anode aluminum foil, which is better than traditional solid-state capacitors, and greatly reduces the equivalent series resistance of the capacitor.

[0003] Existing solid-liquid hybrid electrolytic capacitors typically combine a liquid electrolyte with a solid conductive polymer. However, these capacitors still suffer from issues such as the volatility of traditional solvents at high temperatures, which reduces capacitor lifespan; insufficient solute conductivity; insufficient interfacial contact between the solid conductive polymer and the liquid electrolyte, which increases the equivalent series resistance (ESR); and incompatibility between the liquid and solid electrolytes, which leads to stratification at high temperatures. Consequently, existing solid-liquid hybrid electrolytic capacitors suffer from low conductivity, poor temperature performance, and a short high-temperature lifespan, significantly limiting the use of this technology. Summary of the Invention

[0004] The purpose of the present invention is to provide an electrolyte for a solid-liquid hybrid electrolytic capacitor and an electrolytic capacitor to solve the following technical problems: Existing solid-liquid hybrid electrolytic capacitors have problems such as low electrolyte conductivity, poor temperature performance, and short high-temperature life.

[0005] The purpose of the present invention can be achieved through the following technical solutions: The electrolyte for solid-liquid hybrid electrolytic capacitors includes at least the following components: Liquid components: γ-butyrolactone 40-50%, N-methylpyrrolidone 8-12%, linear carboxylic acid ammonium salt 2-5%, branched long-chain dicarboxylic acid ammonium salt 5-15%, silane coupling agent 1-2%, additives 0.5-5%; Solid components: surface-modified carboxylated PEDOT nanofibers 10-20%, nanoparticles 1-4%.

[0006] As a further embodiment of the present invention, the number of carbon atoms on the main chain of the branched long-chain dicarboxylic acid ammonium salt is 8-12.

[0007] As a further embodiment of the present invention, the method for preparing the branched long-chain dicarboxylic acid ammonium salt comprises at least the following steps: Cyclohexanone and hydrogen peroxide are added to methanol and reacted under the catalysis of FeSO4 to obtain linear carboxylic acid; adding methyl methacrylate to the linear carboxylic acid, and collecting a first fractionated product after the reaction; adding ammonium hydroxide to the first fractionated product, adjusting the pH to acidic after the reaction, and collecting a second fractionated product; The second fractionated product is added into an ethylene glycol solution, and ammonia gas is introduced to adjust the pH to 6-7 to obtain an ethylene glycol solution containing branched long-chain dicarboxylic acid ammonium salt.

[0008] As a further embodiment of the present invention, the molar ratio of the cyclohexanone, the methyl methacrylate and the methanol is 1-2:1-2:10.

[0009] As a further embodiment of the present invention, the content of the branched long-chain dicarboxylic acid ammonium salt in the ethylene glycol solution of the branched long-chain dicarboxylic acid ammonium salt is 15-20%.

[0010] As a further embodiment of the present invention, the preparation method of the surface-modified carboxylated PEDOT nanofibers comprises at least the following steps: PEDOT / PSS nanofibers were dispersed in deionized water, acrylic acid was added, and the mixture was reacted under ultraviolet light, washed, and dried to obtain carboxylated PEDOT nanofibers. Dispersing the carboxylated PEDOT nanofibers in a buffer solution, adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide and stirring to obtain activated nanofibers; Polyethylene glycol is added to the activated nanofibers, reacted, centrifuged, washed and dried to obtain surface-modified carboxylated PEDOT nanofibers.

[0011] As a further embodiment of the present invention, the mass ratio of the PEDOT / PSS nanofibers to the polyethylene glycol is 3-4:1.

[0012] As a further embodiment of the present invention, the linear carboxylate ammonium salt includes at least one of ammonium tetrafluoroborate, ammonium pentaborate, ammonium benzoate, a linear polycarboxylate ammonium salt having 5 to 20 carbon atoms, and a branched polycarboxylate ammonium salt having 5 to 20 carbon atoms, and the additive includes at least one of phosphoric acid, citric acid, ammonium phosphite, ammonium hypophosphite, p-nitrobenzyl alcohol, p-nitrobenzoic acid, nitrophenol, p-nitroanisole, mannitol, sorbitol, xylitol, or an alkyl phosphate.

[0013] As a further embodiment of the present invention, the silane coupling agent includes at least one of γ-(methacryloyloxy)propyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane, and the nanoparticles include at least one of nano-silica particles or nano-titanium dioxide particles.

[0014] An electrolytic capacitor, wherein the electrolyte of the electrolytic capacitor comprises at least any one of the above-mentioned electrolytes for solid-liquid hybrid electrolytic capacitors.

[0015] Beneficial effects of the present invention: The present invention utilizes a branched long-chain dicarboxylic acid ammonium salt as the primary electrolyte and γ-butyrolactone as the primary solvent, and carboxylates and surface-modifies the conductive polymer to produce a solid-liquid hybrid electrolyte for electrolytic capacitors with high conductivity, high flash voltage, and excellent high- and low-temperature stability. The synergistic effect of the liquid and solid components obtained in the present invention enables high-voltage aluminum electrolytic capacitors prepared from this working electrolyte to exhibit low leakage current, high ripple resistance, high-frequency resistance, and high-temperature, long life.

[0016] The present invention provides a solid-liquid hybrid electrolytic capacitor electrolyte solution with a liquid component that uses a branched long-chain dicarboxylic acid ammonium salt as the primary solute and a linear carboxylic acid ammonium salt as the auxiliary solute. The chain length is controlled to balance solubility and viscosity. A higher content of the branched long-chain dicarboxylic acid ammonium salt significantly improves the electrolyte's conductivity, reduces the use of linear carboxylic acid ammonium salt, and provides the electrolyte with a wide temperature range and high- and low-temperature stability. The present invention also uses γ-butyrolactone as the primary solvent and N-methylpyrrolidone as a cosolvent to reduce high-temperature volatilization and polarity differences with the solid component, significantly increasing the electrolyte's flash voltage and enhancing wettability for solid conductive polymers. The present invention also incorporates preservatives, flash enhancers, and hydrogen scavengers as additives. These additives enhance the electrolyte's overall performance, including corrosion resistance and flash voltage, of aluminum electrolytic capacitors. The hydrogen scavenger eliminates gases released from the working electrolyte to reduce pressure within the capacitor.

[0017] The solid component of the electrolyte for solid-liquid hybrid electrolytic capacitors provided in this invention undergoes carboxylation of the conductive polymer and surface coating with polyethylene glycol. Carboxylation increases surface polarity, improving the material's lyophilicity and interfacial compatibility. Polyethylene glycol modification enables the liquid component to adsorb to the surface of the solid conductive polymer, preventing increased interfacial impedance. Nanoparticles are also added to stabilize the two-phase interface through physical adsorption, addressing the problem of high-temperature stratification and improving the overall performance of the capacitor. Furthermore, a silane coupling agent is added to the liquid component of the electrolyte to form chemical bonds at the liquid-solid interface, enhancing bonding strength and significantly improving the compatibility of the solid-liquid hybrid electrolyte. DETAILED DESCRIPTION

[0018] 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.

[0019] Example 1 The method for preparing an ethylene glycol solution of a branched long-chain dicarboxylic acid ammonium salt comprises the following steps: 20 mL of cyclohexanone and 27.5% hydrogen peroxide were added to 60 mL of methanol and reacted under the catalysis of FeSO4 to obtain a linear carboxylic acid; 20 mL of methyl methacrylate was added to the linear carboxylic acid prepared above, and the reaction was carried out at 50-60° C. for 60-120 minutes. After the reaction, a fraction at 125-135° C. was collected to obtain a first fractionated product; 10 mL of 10% ammonium hydroxide was added to the first fractionated product obtained above, the temperature was raised to about 98° C., and the reaction was refluxed for 4 hours. After the reaction, sulfuric acid was added to adjust the pH to 2, and the second fractionated product was collected; The second fractionated product prepared above was added to an ethylene glycol solution, and ammonia gas was introduced to adjust the pH to 7 to obtain an ethylene glycol solution containing 20% ​​of branched long-chain dicarboxylic acid ammonium salt.

[0020] Example 2 The method for preparing an ethylene glycol solution of a branched long-chain dicarboxylic acid ammonium salt comprises the following steps: 20 mL of cyclohexanone and 27.5% hydrogen peroxide were added to 90 mL of methanol and reacted under the catalysis of FeSO4 to obtain a linear carboxylic acid; 25 mL of methyl methacrylate was added to the linear carboxylic acid prepared above, and the reaction was carried out at 50-60° C. for 60-120 minutes. After the reaction, a fraction at 125-135° C. was collected to obtain a first fractionated product; 10 mL of 10% ammonium hydroxide was added to the first fractionated product obtained above, the temperature was raised to about 98° C., and the reaction was refluxed for 4 hours. Sulfuric acid was then added to adjust the pH to 2, and the second fractionated product was collected; The second fractionated product prepared above was added to an ethylene glycol solution, and ammonia gas was introduced to adjust the pH to 7 to obtain an ethylene glycol solution containing 20% ​​of branched long-chain dicarboxylic acid ammonium salt.

[0021] Example 3 The preparation method of surface-modified carboxylated PEDOT nanofibers comprises the following steps: 10 g of PEDOT / PSS nanofibers were dispersed in 100 mL of deionized water, added to 4 g of acrylic acid for ultrasonic dispersion, reacted under UV light for 2 h, washed and dried to obtain carboxylated PEDOT nanofibers; The carboxylated PEDOT nanofibers obtained above were dispersed in 100 mL of MES buffer at pH 5.5, and 0.8 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 0.3 g of N-hydroxysuccinimide were added and stirred to obtain activated nanofibers. 3 g of polyethylene glycol was added to the activated nanofibers, the pH was adjusted to 7.4, and the mixture was reacted at 40° C. for 12 h. The mixture was centrifuged, washed, and freeze-dried to obtain surface-modified carboxylated PEDOT nanofibers.

[0022] Example 4 A method for preparing an electrolyte for a solid-liquid hybrid electrolytic capacitor comprises the following steps: Liquid component: 45% γ-butyrolactone and 10% N-methylpyrrolidone were heated to 120°C, 5% ammonium adipate and 10% ethylene glycol solution of the branched long-chain dicarboxylic acid ammonium salt prepared in Example 1 (calculated on an effective basis) were added, and after complete dissolution, the mixture was cooled to 50°C, and deionized water, 1% γ-aminopropyltriethoxysilane, 0.5% ammonium hypophosphite, 0.5% citric acid, 0.5% p-nitrobenzoic acid, and 0.5% ammonium benzoate were added. After complete dissolution, a liquid component of the electrolyte for a solid-liquid hybrid electrolytic capacitor was obtained.

[0023] Solid component: 18% of the surface-modified carboxylated PEDOT nanofibers prepared in Example 3 and 2% of nano-silicon dioxide were dispersed in deionized water to obtain a solid component of an electrolyte for a solid-liquid hybrid electrolytic capacitor.

[0024] Example 5 A method for preparing an electrolyte for a solid-liquid hybrid electrolytic capacitor comprises the following steps: Liquid component: 45% γ-butyrolactone and 10% N-methylpyrrolidone were heated to 120°C, 3% ammonium adipate and 12% ethylene glycol solution of the branched long-chain dicarboxylic acid ammonium salt prepared in Example 1 (based on the effective matter) were added, and after complete dissolution, the mixture was cooled to 50°C, and deionized water, 1% γ-aminopropyltriethoxysilane, 0.5% ammonium hypophosphite, 0.5% citric acid, 0.5% p-nitrobenzoic acid and 0.5% ammonium benzoate were added. After complete dissolution, a liquid component of the electrolyte for a solid-liquid hybrid electrolytic capacitor was obtained.

[0025] Solid component: 18% of the surface-modified carboxylated PEDOT nanofibers prepared in Example 3 and 2% of nano-silicon dioxide were dispersed in deionized water to obtain a solid component of an electrolyte for a solid-liquid hybrid electrolytic capacitor.

[0026] Comparative Example 1 In the preparation step of the electrolyte for solid-liquid hybrid electrolytic capacitors, compared with Example 4, the branched long-chain dicarboxylic acid ammonium salt prepared in Example 1 was replaced with ammonium adipate in an equal amount during the preparation of the liquid component, and the remaining components and preparation method were exactly the same as in Example 4.

[0027] Comparative Example 2 In the preparation steps of the electrolyte for solid-liquid hybrid electrolytic capacitors, compared with Example 4, during the preparation of the solid component, the surface-modified carboxylated PEDOT nanofibers prepared in Example 3 were replaced with an equal amount of unsurface-modified and uncarboxylated PEDOT nanofibers, and the remaining components and preparation methods were exactly the same as in Example 4.

[0028] Preparation of solid-liquid hybrid electrolytic capacitors: The positive electrode aluminum foil, the negative electrode titanium foil, the chemical fiber electrolytic paper and the guide needle are wound to form a core package; The positive electrode aluminum foil and the guide pin are electrically repaired. The forming liquid used for the formation can be composed of one or more of ammonium adipate, ammonium dihydrogen phosphate, phosphoric acid, and ammonium bicarbonate. After the electrical repair, the core package should be dried to remove moisture in the core package to obtain the formed core package; The core package after chemical formation is immersed in the solid component of the electrolyte obtained in Examples 4-5 and Comparative Examples 1-2 to form a solid electrolyte in the core package, wherein the impregnation adopts an alternating environment of vacuum and air pressure, wherein the vacuum is 95KPa and the pressure can be 0.3Mpa. After the impregnation is completed, heating and drying are performed, wherein the drying temperature can be selected to be 115°C; The core forming the solid electrolyte is immersed in the liquid component of the electrolyte obtained in Examples 4-5 and Comparative Examples 1-2. The electrolyte impregnation can be carried out in a vacuum environment, wherein the vacuum can be -60KPa; The core package impregnated with the liquid component of the electrolyte is assembled with an aluminum shell and a rubber cover, and sealed. The capacitor is aged by passing direct current in a heated environment at a temperature of 105-125° C. to obtain a solid-liquid hybrid electrolytic capacitor.

[0029] Performance testing The conductivity and flash voltage performance of the solid-liquid hybrid electrolytic capacitor electrolytes obtained in Examples 4-5 and Comparative Examples 1-2 were tested at -40°C, 30°C and 120°C. The test results are shown in Tables 1 and 2.

[0030] The solid-liquid hybrid electrolytic capacitors obtained in Test Examples 4-5 and Comparative Examples 1-2 were subjected to a lifespan measurement experiment, with a ripple current of 1.8 A per capacitor loaded. The test time was 2000 hours, where Tanδ is the loss angle, LC is the leakage current, and ΔC is the capacitor capacitance change. The smaller the better. The test results are shown in Table 2.

[0031] Table 1 Performance test results of the products in Examples 4-5 and Comparative Examples 1-2 after reflow soldering

[0032] Table 2 Performance test results of the products in Examples 4-5 and Comparative Examples 1-2 after reflow soldering

[0033] As can be seen from Tables 1 and 2, the electrolyte for solid-liquid hybrid electrolytic capacitors prepared using the method of the present invention exhibits high conductivity, high flash voltage, and good high- and low-temperature stability. Capacitors using the electrolyte prepared using the method of the present invention exhibit low leakage current, high ripple resistance, and long high-temperature life. However, the electrolyte prepared in Comparative Example 1 lacks the addition of branched long-chain dicarboxylic acid ammonium salts, and the solid component prepared in Comparative Example 2 contains unsurface-modified and uncarboxylated PEDOT nanofibers. This results in poor temperature stability for the resulting electrolyte, and a short high-temperature life for the resulting solid-liquid hybrid electrolytic capacitor.

[0034] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. An electrolyte for a solid-liquid hybrid electrolytic capacitor, characterized in that: At least the following components: Liquid components: γ-butyrolactone 40-50%, N-methylpyrrolidone 8-12%, linear carboxylic acid ammonium salt 2-5%, branched long-chain dicarboxylic acid ammonium salt 5-15%, silane coupling agent 1-2%, additives 0.5-5%; Solid components: surface-modified carboxylated PEDOT nanofibers 10-20%, nanoparticles 1-4%.

2. The electrolyte for solid-liquid hybrid electrolytic capacitors according to claim 1, wherein The number of carbon atoms on the main chain of the branched long-chain dicarboxylic acid ammonium salt is 8-12.

3. The electrolyte for solid-liquid hybrid electrolytic capacitors according to claim 2, characterized in that: The preparation method of the branched long-chain dicarboxylic acid ammonium salt comprises at least the following steps: Cyclohexanone and hydrogen peroxide are added to methanol and reacted under the catalysis of FeSO4 to obtain linear carboxylic acid; adding methyl methacrylate to the linear carboxylic acid, and collecting a first fractionated product after the reaction; adding ammonium hydroxide to the first fractionated product, adjusting the pH to acidic after the reaction, and collecting a second fractionated product; The second fractionated product is added into an ethylene glycol solution, and ammonia gas is introduced to adjust the pH to 6-7 to obtain an ethylene glycol solution containing branched long-chain dicarboxylic acid ammonium salt.

4. The electrolyte for solid-liquid hybrid electrolytic capacitors according to claim 3, characterized in that: The molar ratio of the cyclohexanone, the methyl methacrylate and the methanol is 1-2:1-2:

10.

5. The electrolyte for solid-liquid hybrid electrolytic capacitors according to claim 3, characterized in that: The content of the branched long-chain dicarboxylic acid ammonium salt in the ethylene glycol solution of the branched long-chain dicarboxylic acid ammonium salt is 15-20%.

6. The electrolyte for solid-liquid hybrid electrolytic capacitors according to claim 1, wherein The preparation method of the surface-modified carboxylated PEDOT nanofibers comprises at least the following steps: PEDOT / PSS nanofibers were dispersed in deionized water, acrylic acid was added, and the mixture was reacted under ultraviolet light, washed, and dried to obtain carboxylated PEDOT nanofibers. Dispersing the carboxylated PEDOT nanofibers in a buffer solution, adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide and stirring to obtain activated nanofibers; Polyethylene glycol is added to the activated nanofibers, reacted, centrifuged, washed and dried to obtain surface-modified carboxylated PEDOT nanofibers.

7. The electrolyte for solid-liquid hybrid electrolytic capacitors according to claim 6, characterized in that: The mass ratio of the PEDOT / PSS nanofibers to the polyethylene glycol is 3-4:

1.

8. The electrolyte for solid-liquid hybrid electrolytic capacitors according to claim 1, wherein The linear carboxylate ammonium salt includes at least one of ammonium tetrafluoroborate, ammonium pentaborate, ammonium benzoate, linear polycarboxylate ammonium salts with carbon atoms of 5-20, and branched polycarboxylate ammonium salts with carbon atoms of 5-20; the additive includes at least one of phosphoric acid, citric acid, ammonium phosphite, ammonium hypophosphite, p-nitrobenzyl alcohol, p-nitrobenzoic acid, nitrophenol, p-nitroanisole, mannitol, sorbitol, xylitol, or alkyl phosphate.

9. The electrolyte for solid-liquid hybrid electrolytic capacitors according to claim 1, wherein The silane coupling agent includes at least one of γ-(methacryloyloxy)propyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane, and the nanoparticles include at least one of nano-silicon dioxide particles or nano-titanium dioxide particles.

10. An electrolytic capacitor, characterized in that: The electrolyte of the electrolytic capacitor includes at least the electrolyte for the solid-liquid hybrid electrolytic capacitor according to any one of claims 1 to 9.

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