Composite three-dimensional foil electrode material for aluminum electrolytic capacitor and preparation method thereof

Abstract

This invention relates to the field of composite three-dimensional foil electrode materials, specifically to a composite three-dimensional foil electrode material for aluminum electrolytic capacitors and its preparation method, which addresses the problems of low specific capacitance, high equivalent series resistance, insufficient breakdown voltage, and poor cycle stability in aluminum electrolytic capacitor electrode materials. The method involves mixing aluminum powder, ethylene glycol-water mixed solvent, and hydroxypropyl methylcellulose to form a slurry, which is then rolled onto both sides of a base aluminum foil. The slurry is cut into samples, ultrasonically cleaned with anhydrous ethanol and pure water, and immersed in dilute sulfuric acid to obtain a pretreated three-dimensional foil substrate. Boric acid, sodium borate, and deionized water are mixed and stirred, followed by the addition of zirconium oxychloride and stirring. After degassing and settling, a formation solution is obtained. A staged constant-voltage formation is performed using a platinum sheet as the cathode and the pretreated substrate as the anode, followed by immersion in a sealing solution. Finally, a composite conductive aqueous dispersion is rolled onto the dielectric layer surface twice to obtain the composite three-dimensional foil electrode material. This material exhibits high specific capacitance, low equivalent series resistance, high breakdown voltage, and excellent cycle stability.

Description

Technical Field

[0001] This invention relates to the field of composite three-dimensional foil electrode materials, specifically to a composite three-dimensional foil electrode material for aluminum electrolytic capacitors and its preparation method. Background Technology

[0002] Aluminum electrolytic capacitors are core components in the fields of electronics and new energy. Their performance depends on the anode electrode material. As equipment develops towards high-end applications, traditional electrode materials can no longer meet the requirements for high capacity, low loss, and high voltage resistance.

[0003] The industry has developed aluminum powder sintered three-dimensional foil electrodes, but they still have obvious defects: the three-dimensional porous layer has insufficient bonding force with the substrate and is easy to fall off during charge and discharge, which aggravates the deterioration of cycle stability; the dielectric layer is difficult to uniformly cover the porous structure, resulting in low density and many defects, which cannot guarantee that the breakdown voltage meets the standard; the interface between the conventional conductive layer and the dielectric layer is incompatible and has insufficient conductivity, resulting in a high equivalent series resistance of the electrode; and the overall structural design lacks synergy, making it difficult to achieve the comprehensive performance of high specific capacitance, low equivalent series resistance, high withstand voltage and long cycle life at the same time.

[0004] Therefore, developing a composite three-dimensional foil electrode material that can solve the above-mentioned defects and its preparation method has become the key to promoting the high-performance development of aluminum electrolytic capacitors. Summary of the Invention

[0005] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide a composite three-dimensional foil electrode material for aluminum electrolytic capacitors and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions: In a first aspect, this application provides a composite three-dimensional foil electrode material for aluminum electrolytic capacitors, comprising the following components in parts by weight: 50-60 parts aluminum powder, 40-50 parts ethylene glycol-water mixed solvent, 5-6 parts hydroxypropyl methylcellulose, 30-36 parts boric acid, 10-12 parts sodium borate, 1000-1200 parts deionized water, 15-20 parts zirconium oxychloride, 80-100 parts sealing solution, and 35-40 parts composite conductive aqueous dispersion; The composite conductive aqueous dispersion is prepared by the following steps: Step a1: Add 1,1-thiocarbonyldiimidazole and anhydrous acetonitrile to a three-necked flask equipped with a stirrer and thermometer. Purge with nitrogen and stir for 30-32 minutes at 25-30℃ and a stirring rate of 300-400 rpm. Add 2-thiophene methylamine and continue stirring for 15-16 hours. Cover the flask and let it stand for 15-16 hours. Filter and wash the precipitate twice with anhydrous acetone. Then, react the mixture at 50-55℃ and a vacuum of 10...-2 Vacuum drying under Pa conditions for 4-5 hours yields the thiocarbonyl imidazole intermediate. , Step a2: Add the thiocarbonyl imidazole intermediate and anhydrous N,N-dimethylformamide to a three-necked flask equipped with a stirrer, thermometer, and reflux condenser. Purge with nitrogen and stir for 10-12 minutes at a stirring rate of 300-400 rpm. Then add 2-thiophene methylamine, heat to 100°C, and continue stirring for 30 hours. Cool to room temperature, then add crushed ice to the solution and stir for 45-47 minutes. Filter, wash the precipitate three times with deionized water, and then heat at 50-55°C under a vacuum of 10... -2 Vacuum drying under Pa conditions for 4-5 h, eluent added and further purified by column chromatography, yielded di(2-thiophenemethyl)thiourea by recrystallization from ethanol; Step a3: Add bis(2-thiophenemethyl)thiourea, 3,4-ethylenedioxythiophene-anhydrous ethanol solution and deionized water to a round-bottom flask, and sonicate for 10-12 minutes at a power of 200W to obtain solution A. Step a4: Add sodium polystyrene sulfonate and deionized water to a beaker and stir magnetically for 30-35 minutes at a speed of 500 r / min to obtain solution B; Step a5: Add ammonium persulfate, ferric chloride and deionized water to a beaker and stir for 10-12 minutes at a speed of 500 r / min to obtain solution C; Step a6: Pour solution B into solution A, sonicate for 10-12 min, then add solution C, transfer to a round-bottom flask and stir for 10-12 min, adjust the pH to 2-3 with hydrochloric acid, then evacuate the round-bottom flask for 10 min, introduce nitrogen gas at a flow rate of 20 mL / min, place in a 30℃ water bath and stir for 20 h, then transfer to a centrifuge tube and centrifuge at 8000 r / min for 10-12 min, discard the supernatant, wash the precipitate with deionized water, repeat the centrifugation and washing 3 times, then adjust the solid content of the dispersion to 7 wt% with deionized water to obtain the composite conductive water dispersion.

[0007] In a preferred embodiment of the present invention, the ratio of 1,1-thiocarbonyldiimidazole, anhydrous acetonitrile and 2-thiophene methylamine in step a1 is 2.67-5.34 g: 75-150 mL: 1.66-3.32 mL.

[0008] In a preferred embodiment of the present invention, the ratio of the thiocarbonyl imidazole intermediate, anhydrous N,N-dimethylformamide and 2-thiophene methylamine in step a2 is 3-6 g: 75-150 mL: 1.33-2.66 mL.

[0009] In a preferred embodiment of the present invention, the eluent in step a2 is a solution of ethyl acetate and petroleum ether mixed in a volume ratio of 1:50.

[0010] In a preferred embodiment of the present invention, the amount of crushed ice used in step a2 is 80-100g.

[0011] In a preferred embodiment of the present invention, the ratio of the amount of bis(2-thiophenemethyl)thiourea, 3,4-ethylenedioxythiophene-anhydrous ethanol solution and deionized water in step a3 is 0.006-0.012g: 0.32-0.64mL: 10-20mL.

[0012] In a preferred embodiment of the present invention, the 3,4-ethylenedioxythiophene-anhydrous ethanol solution in step a3 is a solution prepared by mixing 3,4-ethylenedioxythiophene and anhydrous ethanol in a ratio of 1g:99mL.

[0013] In a preferred embodiment of the present invention, the ratio of sodium polystyrene sulfonate to deionized water in step a4 is 0.7-1.4g: 20-40mL.

[0014] In a preferred embodiment of the present invention, the sodium polystyrene sulfonate in step a4 is Merck product number 243051.

[0015] In a preferred embodiment of the present invention, the ratio of ammonium persulfate, ferric chloride and deionized water in step a5 is 0.72-1.44g: 0.001-0.002g: 10-20mL.

[0016] In a preferred embodiment of the present invention, the ratio of the amounts of solution A, solution B and solution C in step a6 is 10-12 mL: 20-24 mL: 10-12 mL.

[0017] In a preferred embodiment of the present invention, the concentration of hydrochloric acid in step a6 is 1 mol / L.

[0018] Secondly, this application provides a method for preparing a composite three-dimensional foil electrode material for aluminum electrolytic capacitors, comprising the following steps: Step 1: Weigh out 50-60 parts by weight of aluminum powder, 40-50 parts by weight of ethylene glycol-water mixed solvent, 5-6 parts by weight of hydroxypropyl methylcellulose, 30-36 parts by weight of boric acid, 10-12 parts by weight of sodium borate, 1000-1200 parts by weight of deionized water, 15-20 parts by weight of zirconium oxychloride, 80-100 parts by weight of sealing solution, and 35-40 parts by weight of composite conductive aqueous dispersion, and set aside. Step 2: Place aluminum powder, ethylene glycol-water mixed solvent, and hydroxypropyl methylcellulose in a mixing tank and stir for 30-60 minutes at a speed of 500-800 r / min to obtain a slurry. Use a roller coater to coat both sides of the base aluminum foil with the slurry, controlling the coating thickness to 50-100 μm. Feed the coated aluminum foil into a roller press and compact it under a pressure of 8 MPa. Then, place it in a drying oven at 95-100℃ and dry for 45-47 minutes. Afterward, send it to a sintering furnace and evacuate it to 10℃. -3 Argon gas is introduced after Pa to form an inert gas protective atmosphere. The temperature is raised to 550°C at a heating rate of 8°C / min, held for 90 min, and then cooled to room temperature with the furnace to obtain an aluminum foil with a three-dimensional porous aluminum powder sintered layer on the surface. Step 3: Cut the aluminum foil with the three-dimensional porous aluminum powder sintered layer on the surface into a sample, immerse it in anhydrous ethanol, and ultrasonically clean it for 10-12 minutes under a power of 200W. Then immerse it in pure water and ultrasonically clean it for 10-12 minutes. After that, immerse it in dilute sulfuric acid solution and soak it at room temperature for 3-4 minutes. Rinse it with distilled water 3-4 times and blow the surface moisture with nitrogen to obtain the pretreated three-dimensional foil substrate. Step 4: Add boric acid, sodium borate and deionized water to a beaker, stir for 30-35 minutes at a speed of 300-320 r / min, add zirconium oxychloride, continue stirring for 60-62 minutes, degas by sonication for 20-22 minutes, let stand for 10-12 minutes to obtain the formation solution. Step 5: Pour the formation solution into the electrolytic cell, place the platinum electrode and the pretreated three-dimensional foil substrate, fix the distance between the two electrodes at 5 cm, connect to the electrochemical workstation, turn on the constant temperature stirrer, stabilize the temperature of the formation solution at 30℃, the stirring speed is 200 r / min, and perform staged constant voltage formation. In the first stage, the voltage increase rate is 0.5V / min, and after reaching 40V, the temperature is held constant for 30 min. In the second stage, the voltage increase rate is 1V / min, and after reaching 80V, the temperature is held constant for 60 min. After the formation is completed, turn off the power, keep stirring, and let it cool naturally to room temperature in the formation solution to obtain the composite dielectric layer composite three-dimensional foil. Step Six: Remove the composite dielectric layer composite three-dimensional foil from the electrolytic cell, rinse the surface with deionized water 3-4 times, focusing on rinsing the pore areas of the aluminum powder sintered layer, then place it in a vacuum drying oven. First, dry it at a temperature of 75-80℃ for 60-62 minutes, then transfer it to a muffle furnace, introduce argon gas at a flow rate of 10 mL / min, raise the temperature to 350℃ at a rate of 5℃ / min, hold for 120 minutes, and cool it to room temperature with the furnace. Then, immerse it in a sealing solution at room temperature for 20-22 minutes, rinse it with deionized water 3 times, dry it with nitrogen gas, and then dry it at a temperature of 100℃ and a vacuum degree of 10. -2 Dry in a vacuum drying oven for 30-32 minutes to obtain a three-dimensional composite foil with a sealed composite dielectric layer; Step 7: Take the sealed composite dielectric layer composite 3D foil, immerse it in anhydrous ethanol, and ultrasonically clean it for 10-12 minutes at a power of 150W. After removal, dry the surface with nitrogen and place it in a desiccator. Pour the composite conductive aqueous dispersion into the material tank of the roller coating machine, adjust the cell depth of the microgravure roller, and pass the composite 3D foil through the roller coating roller at a speed of 0.5m / min to coat the surface of the alumina dielectric layer with the composite conductive aqueous dispersion. Two coatings are used. After the first coating, dry it and cool it before coating the second time. Each wet film is 3-5μm thick. After coating, preheat it with an infrared preheating lamp at a temperature of 60℃ for 10 seconds, then send it to a forced-air drying oven and dry it at a temperature of 80-85℃ for 45-47 minutes. After that, transfer it to a vacuum drying oven and dry it at a temperature of 85-90℃ and a vacuum degree of 10. -2 Annealing at Pa for 30-32 min, followed by cooling to room temperature in the oven, yields the composite three-dimensional foil electrode material.

[0019] In a preferred embodiment of the present invention, the base aluminum foil in step two is a high-purity aluminum foil with a purity ≥99.9% and a thickness of 10-20μm.

[0020] In a preferred embodiment of the present invention, the particle size of the aluminum powder in step two is 1-10 μm.

[0021] In a preferred embodiment of the present invention, the ethylene glycol-water mixed solvent in step two is a solution of ethylene glycol and deionized water mixed in a volume ratio of 1:1.

[0022] In a preferred embodiment of the present invention, the hydroxypropyl methylcellulose in step two is Merck product number 423238.

[0023] In a preferred embodiment of the present invention, the concentration of the dilute sulfuric acid solution in step three is 0.5 mol / L.

[0024] In a preferred embodiment of the present invention, the sealing liquid in step six is ​​a 5wt% aqueous solution of phosphoric acid.

[0025] The beneficial effects of this invention are: This invention discloses a composite three-dimensional foil electrode material for aluminum electrolytic capacitors and its preparation method. Aluminum powder is dispersed into a slurry with suitable flowability using an ethylene glycol-water mixed solvent as a dispersant and wetting agent and hydroxypropyl methylcellulose as a binder. This slurry is then physically formed through roller coating and compaction, followed by sintering in an argon inert atmosphere. This process allows for low-temperature metallurgical bonding between the aluminum powder particles, while simultaneously creating a strong interfacial bond between the aluminum powder and the underlying aluminum foil. Upon cooling, a highly interconnected three-dimensional porous structure is formed, providing a high specific surface area substrate for subsequent dielectric layer, film formation, and conductive layer loading. Organic residues on the sintered layer surface were removed by ultrasonic removal with anhydrous ethanol, and the natural oxide film on the aluminum surface was removed by etching with dilute sulfuric acid solution, exposing a fresh aluminum substrate surface and activating active sites, providing a clean and highly reactive substrate for anodic oxidation film formation. Rinsing with pure water and drying with nitrogen gas prevented impurities from affecting the film formation effect. In a borate-sodium borate buffered formation solution system, staged constant-voltage anodic oxidation was performed using pretreated aluminum foil as the anode and platinum sheet as the cathode. The aluminum anode underwent an electrochemical oxidation reaction to generate a dense Al2O3 dielectric layer, while Zr in the formation solution... 4+Under the influence of an electric field, doping is incorporated into the Al2O3 lattice to form an Al2O3-ZrO2 composite dielectric layer. Then, an aqueous phosphoric acid solution is used as a sealing solution, reacting with the active Al-OH bonds on the dielectric layer surface to generate a dense AlPO4 precipitate, filling micropores and microcracks on the dielectric layer surface, thus chemically sealing the pores. Trace impurities on the sealing layer surface are removed ultrasonically with anhydrous ethanol to ensure a clean interface between the conductive and dielectric layers. The composite conductive aqueous dispersion is then coated onto the dielectric layer using a two-coat thin-layer process. Infrared preheating on the surface of the conductive layer enables rapid shaping of the wet film, while forced-air drying gradually removes moisture from the dispersion. Vacuum annealing further enhances the film density of the conductive layer and optimizes the molecular conjugated structure and interfacial bonding state within the conductive layer. This ultimately forms a continuous, pinhole-free conductive layer that is molecularly bonded to the dielectric layer, completing the overall fabrication of the composite three-dimensional foil electrode material. The Al2O3-ZrO2 composite crystalline dielectric layer optimizes the crystal structure, improves the density, dielectric constant, and breakdown insulation performance of the dielectric layer, and reduces electrode leakage current. It can uniformly coat the inner wall of three-dimensional porous channels without clogging the channels, fully preserving the high specific surface area advantage of the substrate to improve the electrode specific capacitance; it can also enrich the surface active sites, enhance the bonding and sealing density with the subsequent sealing layer, and improve the structural stability under high temperature and high frequency conditions, reduce performance degradation, and achieve synergistic effect with the porous substrate, sealing layer and conductive layer, thus optimizing the overall electrical performance of the electrode and extending its service life; the conductive layer is a composite conductive aqueous dispersion coated on the material surface to form a conductive layer, which can not only significantly improve the conductivity of the electrode and have a uniform conductivity distribution, but also effectively reduce the equivalent series resistance of aluminum electrolytic capacitors and meet the requirements of high frequency operation; it can also achieve a strong molecular-level bond with the composite dielectric layer after sealing through intermolecular hydrogen bonds and electrostatic adsorption, solving the problem of easy peeling and detachment of traditional conductive layers. At the same time, the conductive layer has excellent film-forming and leveling properties, and can uniformly penetrate and cover the inner wall of the porous channels of the composite three-dimensional foil to form a continuous pinhole-free film without clogging the channels, fully preserving the core advantage of the high specific surface area of ​​the substrate to ensure the high specific capacitance of the electrode.

[0026] In the preparation of the composite three-dimensional foil electrode material, a composite conductive aqueous dispersion was first prepared. Firstly, under an inert atmosphere of anhydrous acetonitrile, 1,1-thiocarbonyldiimidazole and 2-thiophene methylamine underwent a nucleophilic substitution reaction to generate a thiocarbonyldiimidazole intermediate. After washing with anhydrous acetone and vacuum drying for purification, this intermediate underwent a nitrogen-sulfur condensation reaction with excess 2-thiophene methylamine under reflux conditions of anhydrous N,N-dimethylformamide. After quenching, washing, column chromatography purification, and recrystallization with ethanol, di(2-thiophene methyl)thiourea monomer was obtained. Then... Di(2-thiophenemethyl)thiourea and 3,4-ethylenedioxythiophene-anhydrous ethanol solution were ultrasonically dispersed in an aqueous phase to form a homogeneous solution A. Simultaneously, sodium polystyrene sulfonate and an ammonium persulfate-ferric chloride initiation system were prepared into aqueous solutions B and C, respectively. These three solutions were then mixed and subjected to random radical copolymerization of di(2-thiophenemethyl)thiourea and 3,4-ethylenedioxythiophene in an acidic, nitrogen-protected, oxygen-free aqueous phase system using ammonium persulfate / ferric chloride as a composite initiator. This resulted in the formation of di(2-thiophenemethyl)thiourea-modified conjugated polymer chains. The sulfonate anions of sodium styrene sulfonate dope the conjugated chain through electrostatic interaction to enhance conductivity. Simultaneously, the sodium styrene sulfonate polymer chains encapsulate the copolymer through steric hindrance, forming a stable colloidal dispersion. Finally, impurities are removed by centrifugation and water washing, and the solid content is adjusted to obtain a composite conductive aqueous dispersion. The copolymerization of bis(2-thiophenemethyl)thiourea and 3,4-ethylenedioxythiophene expands the poly(3,4-ethylenedioxythiophene) conjugated π-bond system. Combined with the efficient doping of sodium styrene sulfonate sulfonate groups, the conductivity of the conductive layer is significantly improved. Furthermore, the uniform distribution effectively reduces the equivalent series resistance of capacitors; the thiourea group in the bis(2-thiophenemethyl)thiourea molecule can form hydrogen bonds and electrostatic adsorption with the aluminum-based sealing dielectric layer, achieving molecular-level bonding. The aqueous system can also effectively wet the dielectric layer without corrosion, solving the problems of poor bonding force between the traditional conductive layer and the aluminum base, and easy peeling and detachment; the system has excellent film-forming and leveling properties, retaining the core advantage of high specific surface area of ​​foil; the sodium polystyrene sulfonate polymer chain stably encapsulates the copolymer through steric hindrance effect, making the dispersion highly stable when stored at room temperature in a sealed container. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1: This embodiment describes a method for preparing a composite three-dimensional foil electrode material for aluminum electrolytic capacitors, including the following steps: Step S1: Add 2.67 g of 1,1-thiocarbonyldiimidazole and 75 mL of anhydrous acetonitrile to a three-necked flask equipped with a stirrer and thermometer. Purge with nitrogen and stir for 30 min at 25 °C and a stirring rate of 300 r / min. Add 1.66 mL of 2-thiophene methylamine and continue stirring for 15 h. Cover the flask and let it stand for 15 h. Filter and wash the precipitate twice with anhydrous acetone. Then, react under a vacuum of 10 °C. -2 Vacuum drying under Pa conditions for 4 h yielded the thiocarbonyl imidazole intermediate; Step S2: Add 3g of thiocarbonylimidazolium intermediate and 75mL of anhydrous N,N-dimethylformamide to a three-necked flask equipped with a stirrer, thermometer, and reflux condenser. Purge with nitrogen and stir for 10min at 300r / min. Then add 1.33mL of 2-thiophene methylamine, heat to 100℃, and continue stirring for 30h. Cool to room temperature, then add 80g of crushed ice to the solution and stir for 45min. Filter, wash the precipitate three times with deionized water, and then heat at 50℃ under a vacuum of 10... -2 The product was dried under vacuum for 4 hours under Pa conditions. An eluent (a solution of ethyl acetate and petroleum ether in a volume ratio of 1:50) was added and the product was further purified by column chromatography. The product was then recrystallized from ethanol to obtain di(2-thiophenemethyl)thiourea. Step S3: Add 0.006g of bis(2-thiophenemethyl)thiourea, 0.32mL of 3,4-ethylenedioxythiophene-anhydrous ethanol solution (the 3,4-ethylenedioxythiophene-anhydrous ethanol solution is a solution prepared by mixing 3,4-ethylenedioxythiophene and anhydrous ethanol at a ratio of 1g:99mL) and 10mL of deionized water to a round-bottom flask, and sonicate for 10min at a power of 200W to obtain solution A; Step S4: Add 0.7g of sodium polystyrene sulfonate (sodium polystyrene sulfonate is Merck product number: 243051) and 20mL of deionized water to a beaker, and stir magnetically for 30min at a speed of 500r / min to obtain solution B; Step S5: Add 0.72g ammonium persulfate, 0.001g ferric chloride and 10mL deionized water to a beaker, and stir for 10min at 500r / min to obtain solution C; Step S6: Pour 20 mL of solution B into 10 mL of solution A, sonicate for 10 min, then add 10 mL of solution C, transfer to a round-bottom flask and stir for 10 min. Adjust the pH to 2 with 1 mol / L hydrochloric acid, then evacuate the round-bottom flask for 10 min and introduce nitrogen gas at a flow rate of 20 mL / min. Place in a 30℃ water bath and stir for 20 h. Then transfer to a centrifuge tube and centrifuge at 8000 r / min for 10 min. Discard the supernatant, wash the precipitate with deionized water, repeat the centrifugation and washing 3 times, and then adjust the solid content of the dispersion to 7 wt% with deionized water to obtain the composite conductive water dispersion. Step S7: Weigh out 50 parts by weight of aluminum powder, 40 parts by weight of ethylene glycol-water mixed solvent, 5 parts by weight of hydroxypropyl methylcellulose, 30 parts by weight of boric acid, 10 parts by weight of sodium borate, 1000 parts by weight of deionized water, 15 parts by weight of zirconium oxychloride, 80 parts by weight of sealing liquid and 35 parts by weight of composite conductive aqueous dispersion, and set aside. Step S8: Place aluminum powder (particle size 1μm), ethylene glycol-water mixed solvent (ethylene glycol and deionized water mixed in a 1:1 volume ratio), and hydroxypropyl methylcellulose (Merck product number: 423238) in a mixing tank and stir for 30 minutes at 500 rpm to obtain a slurry. Apply the slurry to both sides of a base aluminum foil (high-purity aluminum foil, purity ≥99.9%, thickness 10μm) using a roller coater, controlling the coating thickness to 50μm. Then, feed the coated aluminum foil into a roller press and compact it under 8MPa pressure. Afterward, dry it in a 95℃ drying oven for 45 minutes, and then send it to a sintering furnace and evacuate it to 10℃. -3 Argon gas is introduced after Pa to form an inert gas protective atmosphere. The temperature is raised to 550°C at a heating rate of 8°C / min, held for 90 min, and then cooled to room temperature with the furnace to obtain an aluminum foil with a three-dimensional porous aluminum powder sintered layer on the surface. Step S9: Cut the aluminum foil with the three-dimensional porous aluminum powder sintered layer on the surface into a sample (10cm×5cm), immerse it in anhydrous ethanol, and ultrasonically clean it for 10min under the condition of 200W power. Then immerse it in pure water and ultrasonically clean it for 10min. Then immerse it in 0.5mol / L dilute sulfuric acid solution and soak it at room temperature for 3min. Rinse it three times with distilled water and blow the surface moisture with nitrogen to obtain the pretreated three-dimensional foil substrate. Step S10: Add boric acid, sodium borate and deionized water to a beaker, stir for 30 min at 300 r / min, add zirconium oxychloride, continue stirring for 60 min, degas by sonication for 20 min, let stand for 10 min to obtain the formation solution. Step S11: Pour the formation solution into the electrolytic cell, place a platinum sheet electrode (cathode, an electrode with an area matching the anode) and a pretreated three-dimensional foil substrate (anode), fix the distance between the two electrodes at 5 cm, connect to the electrochemical workstation, turn on the constant temperature stirrer, stabilize the temperature of the formation solution at 30℃, and the stirring speed at 200 r / min. Perform staged constant voltage formation. In the first stage, the voltage increase rate is 0.5 V / min, and after reaching 40 V, maintain the temperature for 30 min. In the second stage, the voltage increase rate is 1 V / min, and after reaching 80 V, maintain the temperature for 60 min. After the formation is completed, turn off the power, keep stirring, and allow it to cool naturally to room temperature in the formation solution to obtain a composite dielectric layer composite three-dimensional foil. Step S12: Remove the composite dielectric layer composite three-dimensional foil from the electrolytic cell, rinse the surface three times with deionized water, focusing on rinsing the pore area of ​​the aluminum powder sintered layer, then place it in a vacuum drying oven and dry it at 75℃ for 60 min. Afterward, transfer it to a muffle furnace, introduce argon gas at a flow rate of 10 mL / min, raise the temperature to 350℃ at a rate of 5℃ / min, hold for 120 min, and cool it to room temperature with the furnace. Then, immerse it in a sealing solution (5 wt% phosphoric acid aqueous solution) at room temperature for 20 min, rinse three times with deionized water, dry it with nitrogen, and then dry it at 100℃ under a vacuum of 10... -2 The composite three-dimensional foil with sealed composite dielectric layer was dried in a vacuum drying oven for 30 minutes to obtain the composite three-dimensional foil with sealed composite dielectric layer. Step S13: Take the sealed composite dielectric layer composite 3D foil, immerse it in anhydrous ethanol, and ultrasonically clean it for 10 minutes at a power of 150W. After removing it, dry the surface with nitrogen and place it in a desiccator. Pour the composite conductive aqueous dispersion into the material tank of the roller coating machine, adjust the cell depth of the microgravure roller, and pass the composite 3D foil through the roller coating roller at a speed of 0.5m / min to coat the surface of the alumina dielectric layer with the composite conductive aqueous dispersion. Two coatings are used. After the first coating, dry it and cool it before coating the second time. Each wet film is 3μm. After coating, preheat it with an infrared preheating lamp at a temperature of 60℃ for 10s, then send it to a forced-air drying oven and dry it at a temperature of 80℃ for 45 minutes. After that, transfer it to a vacuum drying oven and dry it at a temperature of 85℃ and a vacuum degree of 10. - 2 Annealing at Pa for 30 min and then cooling to room temperature in the oven yields a composite three-dimensional foil electrode material.

[0029] Example 2: This embodiment describes a method for preparing a composite three-dimensional foil electrode material for aluminum electrolytic capacitors, including the following steps: Step S1: Add 4g of 1,1-thiocarbonyldiimidazole and 112.5mL of anhydrous acetonitrile to a three-necked flask equipped with a stirrer and thermometer. Purge with nitrogen and stir for 31min at 27℃ and a stirring rate of 350r / min. Add 2.49mL of 2-thiophene methylamine and continue stirring for 15.5h. Cover the flask and let it stand for 15.5h. Filter and wash the precipitate twice with anhydrous acetone. Then, react under a vacuum of 10℃. -2 Vacuum drying under Pa conditions for 4.5 h yielded a thiocarbonyl imidazole intermediate. Step S2: 4.5 g of thiocarbonylimidazolium intermediate and 112.5 mL of anhydrous N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, thermometer, and reflux condenser. Nitrogen gas was introduced for protection, and the mixture was stirred at 350 r / min for 11 min. Then, 2 mL of 2-thiophene methylamine was added, and the mixture was heated to 100 °C and stirred for 30 h. After cooling to room temperature, 90 g of crushed ice was added to the solution, and the mixture was stirred for 46 min. The mixture was filtered, and the precipitate was washed three times with deionized water. Finally, the mixture was heated at 53 °C under a vacuum of 10... -2 The product was dried under vacuum for 4.5 h under Pa conditions, and then further purified by column chromatography with the addition of eluent (a solution of ethyl acetate and petroleum ether mixed in a volume ratio of 1:50). The product was then recrystallized from ethanol to obtain di(2-thiophenemethyl)thiourea. Step S3: Add 0.009g of bis(2-thiophenemethyl)thiourea, 0.48mL of 3,4-ethylenedioxythiophene-anhydrous ethanol solution (the 3,4-ethylenedioxythiophene-anhydrous ethanol solution is a solution prepared by mixing 3,4-ethylenedioxythiophene and anhydrous ethanol at a ratio of 1g:99mL) and 15mL of deionized water into a round-bottom flask, and sonicate for 11min at a power of 200W to obtain solution A; Step S4: Add 1.05g of sodium polystyrene sulfonate (sodium polystyrene sulfonate is Merck product number: 243051) and 30mL of deionized water to a beaker, and stir magnetically for 33min at a speed of 500r / min to obtain solution B; Step S5: Add 1.08g ammonium persulfate, 0.0015g ferric chloride and 15mL deionized water to a beaker, and stir for 11min at 500r / min to obtain solution C; Step S6: Pour 22 mL of solution B into 11 mL of solution A, sonicate for 11 min, then add 11 mL of solution C, transfer to a round-bottom flask and stir for 11 min. Adjust the pH to 2.5 with 1 mol / L hydrochloric acid, then evacuate the round-bottom flask for 10 min and introduce nitrogen gas at a flow rate of 20 mL / min. Place in a 30℃ water bath and stir for 20 h. Then transfer to a centrifuge tube and centrifuge at 8000 r / min for 11 min. Discard the supernatant, wash the precipitate with deionized water, repeat the centrifugation and washing 3 times, and then adjust the solid content of the dispersion to 7 wt% with deionized water to obtain the composite conductive water dispersion. Step S7: Weigh out 55 parts aluminum powder, 45 parts ethylene glycol-water mixed solvent, 5.5 parts hydroxypropyl methylcellulose, 33 parts boric acid, 11 parts sodium borate, 1100 parts deionized water, 17 parts zirconium oxychloride, 90 parts sealing liquid, and 37 parts composite conductive aqueous dispersion by weight, and set aside. Step S8: Place aluminum powder (particle size 5μm), ethylene glycol-water mixed solvent (ethylene glycol and deionized water mixed in a 1:1 volume ratio), and hydroxypropyl methylcellulose (Merck product number: 423238) in a mixing tank and stir for 45 minutes at 650 rpm to obtain a slurry. Apply the slurry to both sides of a base aluminum foil (high-purity aluminum foil, purity ≥99.9%, thickness 10-20μm) using a roller coater, controlling the coating thickness to 75μm. Then, feed the coated aluminum foil into a roller press and compact it under 8MPa pressure. Afterward, dry it in a 97℃ drying oven for 46 minutes, and then send it to a sintering furnace and evacuate it to 10℃. -3 Argon gas is introduced after Pa to form an inert gas protective atmosphere. The temperature is raised to 550°C at a heating rate of 8°C / min, held for 90 min, and then cooled to room temperature with the furnace to obtain an aluminum foil with a three-dimensional porous aluminum powder sintered layer on the surface. Step S9: Cut the aluminum foil with the three-dimensional porous aluminum powder sintered layer on the surface into a sample (10cm×5cm), immerse it in anhydrous ethanol, and ultrasonically clean it for 11min under a power of 200W. Then immerse it in pure water and ultrasonically clean it for 11min. After that, immerse it in 0.5mol / L dilute sulfuric acid solution and soak it at room temperature for 3.5min. Rinse it three times with distilled water and blow the surface moisture with nitrogen to obtain the pretreated three-dimensional foil substrate. Step S10: Add boric acid, sodium borate and deionized water to a beaker, stir for 33 min at 310 r / min, add zirconium oxychloride, continue stirring for 61 min, degas by sonication for 21 min, let stand for 11 min to obtain the formation solution. Step S11: Pour the formation solution into the electrolytic cell, place a platinum sheet electrode (cathode, an electrode with an area matching the anode) and a pretreated three-dimensional foil substrate (anode), fix the distance between the two electrodes at 5 cm, connect to the electrochemical workstation, turn on the constant temperature stirrer, stabilize the temperature of the formation solution at 30℃, and the stirring speed at 200 r / min. Perform staged constant voltage formation. In the first stage, the voltage increase rate is 0.5 V / min, and after reaching 40 V, maintain the temperature for 30 min. In the second stage, the voltage increase rate is 1 V / min, and after reaching 80 V, maintain the temperature for 60 min. After the formation is completed, turn off the power, keep stirring, and allow it to cool naturally to room temperature in the formation solution to obtain a composite dielectric layer composite three-dimensional foil. Step S12: Remove the composite dielectric layer composite three-dimensional foil from the electrolytic cell, rinse the surface three times with deionized water, focusing on rinsing the pore area of ​​the aluminum powder sintered layer, then place it in a vacuum drying oven and dry it at 77℃ for 61 min. Afterward, transfer it to a muffle furnace, introduce argon gas at a flow rate of 10 mL / min, raise the temperature to 350℃ at a rate of 5℃ / min, hold for 120 min, and cool it to room temperature with the furnace. Then, immerse it in a sealing solution (5 wt% phosphoric acid aqueous solution) at room temperature for 21 min, rinse three times with deionized water, dry it with nitrogen, and then dry it at 100℃ under a vacuum of 10... -2 The composite three-dimensional foil with sealed composite dielectric layer was dried in a vacuum drying oven for 31 min to obtain the composite three-dimensional foil with sealed composite dielectric layer. Step S13: Take the sealed composite dielectric layer composite 3D foil, immerse it in anhydrous ethanol, and ultrasonically clean it for 11 minutes at a power of 150W. After removing it, dry the surface with nitrogen and place it in a desiccator. Pour the composite conductive aqueous dispersion into the material tank of the roller coating machine, adjust the cell depth of the microgravure roller, and pass the composite 3D foil through the roller coating roller at a speed of 0.5m / min to coat the composite conductive aqueous dispersion onto the surface of the alumina dielectric layer. Two coatings are used. After the first coating, dry it and cool it before coating the second time. Each wet film is 4μm. After coating, preheat it with an infrared preheating lamp at a temperature of 60℃ for 10s, then send it to a forced-air drying oven and dry it at a temperature of 83℃ for 46 minutes. After that, transfer it to a vacuum drying oven and dry it at a temperature of 87℃ and a vacuum degree of 10. - 2 Annealing at Pa for 31 min and then cooling to room temperature in the oven yields a composite three-dimensional foil electrode material.

[0030] Example 3: This embodiment describes a method for preparing a composite three-dimensional foil electrode material for aluminum electrolytic capacitors, including the following steps: Step S1: Add 5.34 g of 1,1-thiocarbonyldiimidazole and 150 mL of anhydrous acetonitrile to a three-necked flask equipped with a stirrer and thermometer. Purge with nitrogen and stir for 32 min at 30 °C and a stirring rate of 400 r / min. Add 3.32 mL of 2-thiophene methylamine and continue stirring for 16 h. Cover the flask and let it stand for 16 h. Filter and wash the precipitate twice with anhydrous acetone. Then, react at 55 °C and a vacuum of 10... -2 Vacuum drying for 5 h under Pa conditions yielded the thiocarbonyl imidazole intermediate. Step S2: Add 6g of thiocarbonylimidazolium intermediate and 150mL of anhydrous N,N-dimethylformamide to a three-necked flask equipped with a stirrer, thermometer, and reflux condenser. Purge with nitrogen and stir for 12min at 400r / min. Then add 2.66mL of 2-thiophene methylamine, heat to 100℃, and continue stirring for 30h. Cool to room temperature, then add 100g of crushed ice to the solution and stir for 47min. Filter, wash the precipitate three times with deionized water, and then heat at 55℃ under a vacuum of 10... -2 The product was dried under vacuum for 5 hours under Pa conditions. Then, an eluent (a solution of ethyl acetate and petroleum ether in a volume ratio of 1:50) was added and the product was further purified by column chromatography. The product was then recrystallized from ethanol to obtain di(2-thiophenemethyl)thiourea. Step S3: Add 0.012g of bis(2-thiophenemethyl)thiourea, 0.64mL of 3,4-ethylenedioxythiophene-anhydrous ethanol solution (the 3,4-ethylenedioxythiophene-anhydrous ethanol solution is a solution prepared by mixing 3,4-ethylenedioxythiophene and anhydrous ethanol at a ratio of 1g:99mL) and 20mL of deionized water into a round-bottom flask, and sonicate for 12min at a power of 200W to obtain solution A; Step S4: Add 1.4g of sodium polystyrene sulfonate (sodium polystyrene sulfonate is Merck product number: 243051) and 40mL of deionized water to a beaker, and stir magnetically for 35min at a speed of 500r / min to obtain solution B; Step S5: Add 1.44g ammonium persulfate, 0.002g ferric chloride and 20mL deionized water to a beaker, and stir for 12min at 500r / min to obtain solution C; Step S6: Pour 24 mL of solution B into 12 mL of solution A, sonicate for 12 min, then add 12 mL of solution C, transfer to a round-bottom flask and stir for 12 min. Adjust the pH to 3 with 1 mol / L hydrochloric acid, then evacuate the round-bottom flask for 10 min and introduce nitrogen gas at a flow rate of 20 mL / min. Place in a 30℃ water bath and stir for 20 h. Then transfer to a centrifuge tube and centrifuge at 8000 r / min for 12 min. Discard the supernatant, wash the precipitate with deionized water, repeat the centrifugation and washing 3 times, and then adjust the solid content of the dispersion to 7 wt% with deionized water to obtain the composite conductive water dispersion. Step S7: Weigh out 60 parts by weight of aluminum powder, 50 parts by weight of ethylene glycol-water mixed solvent, 6 parts by weight of hydroxypropyl methylcellulose, 36 parts by weight of boric acid, 12 parts by weight of sodium borate, 1200 parts by weight of deionized water, 20 parts by weight of zirconium oxychloride, 100 parts by weight of sealing liquid and 40 parts by weight of composite conductive aqueous dispersion, and set aside. Step S8: Aluminum powder (particle size 10 μm), ethylene glycol-water mixed solvent (ethylene glycol and deionized water mixed in a 1:1 volume ratio), and hydroxypropyl methylcellulose (Merck product number: 423238) are placed in a mixing tank and stirred for 60 minutes at 800 rpm to obtain a slurry. The slurry is then coated onto both sides of a base aluminum foil (high-purity aluminum foil, purity ≥99.9%, thickness 20 μm) using a roller coater, with the coating thickness controlled at 100 μm. The coated aluminum foil is then fed into a roller press and compacted under 8 MPa pressure. Afterward, it is dried in a 100℃ drying oven for 47 minutes, and then sent to a sintering furnace and evacuated to 10℃. -3 Argon gas is introduced after Pa to form an inert gas protective atmosphere. The temperature is raised to 550°C at a heating rate of 8°C / min, held for 90 min, and then cooled to room temperature with the furnace to obtain an aluminum foil with a three-dimensional porous aluminum powder sintered layer on the surface. Step S9: Cut the aluminum foil with the three-dimensional porous aluminum powder sintered layer on the surface into a sample (10cm×5cm), immerse it in anhydrous ethanol, and ultrasonically clean it for 12min under a power of 200W. Then immerse it in pure water and ultrasonically clean it for 12min. After that, immerse it in 0.5mol / L dilute sulfuric acid solution and soak it at room temperature for 4min. Rinse it 4 times with distilled water and blow the surface moisture with nitrogen to obtain the pretreated three-dimensional foil substrate. Step S10: Add boric acid, sodium borate and deionized water to a beaker, stir for 35 min at 320 r / min, add zirconium oxychloride, continue stirring for 62 min, degas by sonication for 22 min, let stand for 12 min to obtain the formation solution. Step S11: Pour the formation solution into the electrolytic cell, place a platinum sheet electrode (cathode, an electrode with an area matching the anode) and a pretreated three-dimensional foil substrate (anode), fix the distance between the two electrodes at 5 cm, connect to the electrochemical workstation, turn on the constant temperature stirrer, stabilize the temperature of the formation solution at 30℃, and the stirring speed at 200 r / min. Perform staged constant voltage formation. In the first stage, the voltage increase rate is 0.5 V / min, and after reaching 40 V, maintain the temperature for 30 min. In the second stage, the voltage increase rate is 1 V / min, and after reaching 80 V, maintain the temperature for 60 min. After the formation is completed, turn off the power, keep stirring, and allow it to cool naturally to room temperature in the formation solution to obtain a composite dielectric layer composite three-dimensional foil. Step S12: Remove the composite dielectric layer composite three-dimensional foil from the electrolytic cell, rinse the surface four times with deionized water, focusing on rinsing the pore area of ​​the aluminum powder sintered layer, then place it in a vacuum drying oven and dry it at 80℃ for 62 min. Afterward, transfer it to a muffle furnace, introduce argon gas at a flow rate of 10 mL / min, raise the temperature to 350℃ at a rate of 5℃ / min, hold for 120 min, and cool it to room temperature with the furnace. Then, immerse it in a sealing solution (5wt% phosphoric acid aqueous solution) at room temperature for 22 min, rinse three times with deionized water, dry it with nitrogen, and then heat it at 100℃ under a vacuum of 10... -2 The composite three-dimensional foil with sealed composite dielectric layer was dried in a vacuum drying oven for 32 min to obtain the composite three-dimensional foil with sealed composite dielectric layer. Step S13: Take the sealed composite dielectric layer composite 3D foil, immerse it in anhydrous ethanol, and ultrasonically clean it for 12 minutes at a power of 150W. After removing it, dry the surface with nitrogen and place it in a desiccator. Pour the composite conductive aqueous dispersion into the material tank of the roller coating machine, adjust the cell depth of the microgravure roller, and pass the composite 3D foil through the roller coating roller at a speed of 0.5m / min to coat the composite conductive aqueous dispersion onto the surface of the alumina dielectric layer. Two coatings are used. After the first coating, dry it and cool it before coating the second time. Each wet film is 5μm. After coating, preheat it with an infrared preheating lamp at a temperature of 60℃ for 10s, then send it to a forced-air drying oven and dry it at a temperature of 85℃ for 47 minutes. After that, transfer it to a vacuum drying oven and dry it at a temperature of 90℃ and a vacuum degree of 10. - 2 Annealing at Pa for 32 min and then cooling to room temperature in the oven yields a composite three-dimensional foil electrode material.

[0031] Comparative Example 1: This comparative example illustrates a method for preparing a composite three-dimensional foil electrode material for aluminum electrolytic capacitors, comprising the following steps: Step S1: Weigh out 50 parts by weight of aluminum powder, 40 parts by weight of ethylene glycol-water mixed solvent, 5 parts by weight of hydroxypropyl methylcellulose, 30 parts by weight of boric acid, 10 parts by weight of sodium borate, 1000 parts by weight of deionized water, 15 parts by weight of zirconium oxychloride, and 80 parts by weight of sealing liquid, and set aside. Step S2: Aluminum powder (particle size 1μm), ethylene glycol-water mixed solvent (ethylene glycol and deionized water mixed in a 1:1 volume ratio), and hydroxypropyl methylcellulose (Merck product number: 423238) are placed in a mixing tank and stirred for 30 minutes at 500 rpm to obtain a slurry. The slurry is then coated onto both sides of a base aluminum foil (high-purity aluminum foil, purity ≥99.9%, thickness 10μm) using a roller coater, with the coating thickness controlled at 50μm. The coated aluminum foil is then fed into a roller press and compacted under 8MPa pressure. Afterward, it is dried in a 95℃ drying oven for 45 minutes, and then sent to a sintering furnace and evacuated to 10℃. -3 Argon gas is introduced after Pa to form an inert gas protective atmosphere. The temperature is raised to 550°C at a heating rate of 8°C / min, held for 90 min, and then cooled to room temperature with the furnace to obtain an aluminum foil with a three-dimensional porous aluminum powder sintered layer on the surface. Step S3: Cut the aluminum foil with the three-dimensional porous aluminum powder sintered layer on the surface into a sample (10cm×5cm), immerse it in anhydrous ethanol, and ultrasonically clean it for 10min under a power of 200W. Then immerse it in pure water and ultrasonically clean it for 10min. After that, immerse it in 0.5mol / L dilute sulfuric acid solution and soak it at room temperature for 3min. Rinse it three times with distilled water and blow the surface moisture with nitrogen to obtain the pretreated three-dimensional foil substrate. Step S4: Add boric acid, sodium borate and deionized water to a beaker, stir for 30 min at 300 r / min, add zirconium oxychloride, continue stirring for 60 min, degas by sonication for 20 min, let stand for 10 min to obtain the formation solution. Step S5: Pour the formation solution into the electrolytic cell, place a platinum sheet electrode (cathode, an electrode with an area matching the anode) and a pretreated three-dimensional foil substrate (anode), with the distance between the two electrodes fixed at 5 cm, connect to the electrochemical workstation, turn on the constant temperature stirrer, stabilize the temperature of the formation solution at 30℃, and the stirring speed at 200 r / min. Perform staged constant voltage formation. In the first stage, the voltage increase rate is 0.5 V / min, and after reaching 40 V, the temperature is maintained for 30 min. In the second stage, the voltage increase rate is 1 V / min, and after reaching 80 V, the temperature is maintained for 60 min. After the formation is completed, turn off the power, keep stirring, and allow it to cool naturally to room temperature in the formation solution to obtain a composite dielectric layer composite three-dimensional foil. Step S6: Remove the composite dielectric layer composite three-dimensional foil from the electrolytic cell, rinse the surface three times with deionized water, focusing on rinsing the pore area of ​​the aluminum powder sintered layer, then place it in a vacuum drying oven and dry it at 75℃ for 60 min. Afterward, transfer it to a muffle furnace, introduce argon gas at a flow rate of 10 mL / min, raise the temperature to 350℃ at a rate of 5℃ / min, hold for 120 min, and cool it to room temperature with the furnace. Then, immerse it in a sealing solution (5wt% phosphoric acid aqueous solution) at room temperature for 20 min, rinse three times with deionized water, dry it with nitrogen, and then dry it at 100℃ under a vacuum of 10... -2 The composite three-dimensional foil electrode material was obtained by drying in a vacuum drying oven for 30 minutes.

[0032] Comparative Example 2: This comparative example illustrates a method for preparing a composite three-dimensional foil electrode material for aluminum electrolytic capacitors, comprising the following steps: Step S1: Add 2.67 g of 1,1-thiocarbonyldiimidazole and 75 mL of anhydrous acetonitrile to a three-necked flask equipped with a stirrer and thermometer. Purge with nitrogen and stir for 30 min at 25 °C and a stirring rate of 300 r / min. Add 1.66 mL of 2-thiophene methylamine and continue stirring for 15 h. Cover the flask and let it stand for 15 h. Filter and wash the precipitate twice with anhydrous acetone. Then, react under a vacuum of 10 °C. -2 Vacuum drying under Pa conditions for 4 h yielded the thiocarbonyl imidazole intermediate; Step S2: Add 3g of thiocarbonylimidazolium intermediate and 75mL of anhydrous N,N-dimethylformamide to a three-necked flask equipped with a stirrer, thermometer, and reflux condenser. Purge with nitrogen and stir for 10min at 300r / min. Then add 1.33mL of 2-thiophene methylamine, heat to 100℃, and continue stirring for 30h. Cool to room temperature, then add 80g of crushed ice to the solution and stir for 45min. Filter, wash the precipitate three times with deionized water, and then heat at 50℃ under a vacuum of 10... -2 The product was dried under vacuum for 4 hours under Pa conditions. An eluent (a solution of ethyl acetate and petroleum ether in a volume ratio of 1:50) was added and the product was further purified by column chromatography. The product was then recrystallized from ethanol to obtain di(2-thiophenemethyl)thiourea. Step S3: Add 0.006g of bis(2-thiophenemethyl)thiourea, 0.32mL of 3,4-ethylenedioxythiophene-anhydrous ethanol solution (the 3,4-ethylenedioxythiophene-anhydrous ethanol solution is a solution prepared by mixing 3,4-ethylenedioxythiophene and anhydrous ethanol at a ratio of 1g:99mL) and 10mL of deionized water to a round-bottom flask, and sonicate for 10min at a power of 200W to obtain solution A; Step S4: Add 0.7g of sodium polystyrene sulfonate (sodium polystyrene sulfonate is Merck product number: 243051) and 20mL of deionized water to a beaker, and stir magnetically for 30min at a speed of 500r / min to obtain solution B; Step S5: Add 0.72g ammonium persulfate, 0.001g ferric chloride and 10mL deionized water to a beaker, and stir for 10min at 500r / min to obtain solution C; Step S6: Pour 20 mL of solution B into 10 mL of solution A, sonicate for 10 min, then add 10 mL of solution C, transfer to a round-bottom flask and stir for 10 min. Adjust the pH to 2 with 1 mol / L hydrochloric acid, then evacuate the round-bottom flask for 10 min and introduce nitrogen gas at a flow rate of 20 mL / min. Place in a 30℃ water bath and stir for 20 h. Then transfer to a centrifuge tube and centrifuge at 8000 r / min for 10 min. Discard the supernatant, wash the precipitate with deionized water, repeat the centrifugation and washing 3 times, and then adjust the solid content of the dispersion to 7 wt% with deionized water to obtain the composite conductive water dispersion. Step S7: Weigh out 50 parts by weight of aluminum powder, 40 parts by weight of ethylene glycol-water mixed solvent, 5 parts by weight of hydroxypropyl methylcellulose and 35 parts by weight of composite conductive aqueous dispersion, and set aside. Step S8: Place aluminum powder (particle size 1μm), ethylene glycol-water mixed solvent (ethylene glycol and deionized water mixed in a 1:1 volume ratio), and hydroxypropyl methylcellulose (Merck product number: 423238) in a mixing tank and stir for 30 minutes at 500 rpm to obtain a slurry. Apply the slurry to both sides of a base aluminum foil (high-purity aluminum foil, purity ≥99.9%, thickness 10μm) using a roller coater, controlling the coating thickness to 50μm. Then, feed the coated aluminum foil into a roller press and compact it under 8MPa pressure. Afterward, dry it in a 95℃ drying oven for 45 minutes, and then send it to a sintering furnace and evacuate it to 10℃. -3 Argon gas is introduced after Pa to form an inert gas protective atmosphere. The temperature is raised to 550°C at a heating rate of 8°C / min, held for 90 min, and then cooled to room temperature with the furnace to obtain an aluminum foil with a three-dimensional porous aluminum powder sintered layer on the surface. Step S9: Cut the aluminum foil with the three-dimensional porous aluminum powder sintered layer on the surface into samples (10cm×5cm), immerse it in anhydrous ethanol, and ultrasonically clean it for 10 minutes at a power of 150W. After removal, dry the surface with nitrogen and place it in a desiccator. Pour the composite conductive aqueous dispersion into the material tank of the roller coating machine, adjust the cell depth of the microgravure roller, and pass the composite three-dimensional foil through the roller coating roller at a speed of 0.5m / min to coat the surface of the composite conductive aqueous dispersion. Two coatings are used. After the first coating, dry it and cool it before coating the second time. Each wet film is 3μm. After coating, preheat it with an infrared preheating lamp at a temperature of 60℃ for 10s, then put it into a forced-air drying oven and dry it at a temperature of 80℃ for 45 minutes. After that, transfer it to a vacuum drying oven and dry it at a temperature of 85℃ and a vacuum degree of 10. -2 Annealing at Pa for 30 min and then cooling to room temperature in the oven yields a composite three-dimensional foil electrode material.

[0033] Comparative Example 3: This comparative example illustrates a method for preparing a composite three-dimensional foil electrode material for aluminum electrolytic capacitors, comprising the following steps: Step S1: Weigh out 50 parts by weight of aluminum powder, 40 parts by weight of ethylene glycol-water mixed solvent and 5 parts by weight of hydroxypropyl methylcellulose, and set aside. Step S2: Aluminum powder (particle size 1μm), ethylene glycol-water mixed solvent (ethylene glycol and deionized water mixed in a 1:1 volume ratio), and hydroxypropyl methylcellulose (Merck product number: 423238) are placed in a mixing tank and stirred for 30 minutes at 500 rpm to obtain a slurry. The slurry is then coated onto both sides of a base aluminum foil (high-purity aluminum foil, purity ≥99.9%, thickness 10μm) using a roller coater, with the coating thickness controlled at 50μm. The coated aluminum foil is then fed into a roller press and compacted under 8MPa pressure. Afterward, it is dried in a 95℃ drying oven for 45 minutes, and then sent to a sintering furnace and evacuated to 10℃. -3 Argon gas was introduced after Pa to form an inert protective atmosphere. The temperature was increased to 550℃ at a rate of 8℃ / min and held for 90min. The furnace was then cooled to room temperature and cut into samples (10cm×5cm) to obtain the composite three-dimensional foil electrode material.

[0034] Performance testing: The composite three-dimensional foil electrode materials of Examples 1-3 and Comparative Examples 1-3 were tested according to the following methods; Mass specific capacitance test: A three-electrode system was used with an electrochemical workstation, using a saturated calomel electrode as the reference electrode, a platinum sheet as the counter electrode, and 1 mol / L sulfuric acid as the electrolyte. The test was conducted using a constant current charge-discharge method with a voltage window of 0-0.8V and a current density of 1 mA / cm². 2 Calculate the mass-to-capacitance ratio.

[0035] Equivalent series resistance test: Using an LCR digital bridge, an analog capacitor is assembled and tested at a frequency of 100kHz. The lower the value, the better the conductivity and charge transport performance.

[0036] Breakdown withstand voltage test: Using a withstand voltage tester, the sample is fully wetted with electrolyte, and the voltage is increased at a constant rate of 0.5V / s. The critical breakdown voltage when the current increases suddenly is recorded.

[0037] 1000-cycle capacitance retention test: constant current charge-discharge cycle tester, 1mA / cm 2 Complete 1000 cycles at the current density and calculate the percentage of capacitance retained relative to the initial value after the cycles.

[0038] The test results are shown in Table 1: Table 1: Test Results Summary Table , Referring to Table 1, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the composite three-dimensional foil electrode material has high specific capacitance, low equivalent series resistance, high breakdown voltage, and excellent cycle stability.

[0039] Based on the comparison between Example 1 and Comparative Example 1, it can be seen that Comparative Example 1 has no conductive layer but has a dielectric layer. Due to the lack of a highly efficient conductive layer, charge transport is hindered, the specific capacitance decreases significantly, the equivalent series resistance increases significantly, the cycle stability deteriorates, and the breakdown voltage remains high because the dielectric layer is intact.

[0040] Based on the comparison between Example 1 and Comparative Example 2, it can be seen that Comparative Example 2 has a conductive layer but no dielectric layer. Without a dielectric layer, an effective energy storage medium cannot be formed. Only a weak double-layer capacitance exists, resulting in extremely low specific capacitance. The lack of an effective insulating layer leads to breakdown voltage failure, and the electrolyte directly corrodes the substrate, resulting in extremely poor cycle performance.

[0041] Based on the comparison between Example 1 and Comparative Example 3, it can be seen that Comparative Example 3 has no functional layer and relies solely on the characteristics of the aluminum substrate itself. All performance indicators are the worst, and it has no value as a capacitor electrode.

[0042] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. A composite three-dimensional foil electrode material for aluminum electrolytic capacitors, characterized in that, Includes the following components by weight: 50-60 parts aluminum powder, 40-50 parts ethylene glycol-water mixed solvent, 5-6 parts hydroxypropyl methylcellulose, 30-36 parts boric acid, 10-12 parts sodium borate, 1000-1200 parts deionized water, 15-20 parts zirconium oxychloride, 80-100 parts sealing solution, and 35-40 parts composite conductive aqueous dispersion; The composite conductive aqueous dispersion is prepared by the following steps: Step a1: Mix 1,1-thiocarbonyldiimidazole and anhydrous acetonitrile, stir and react, add 2-thiophene methylamine and continue stirring, let stand, filter and wash, and then vacuum dry to obtain thiocarbonyldiimidazole intermediate; Step a2: Mix the thiocarbonyl imidazole intermediate and anhydrous N,N-dimethylformamide, stir, then add 2-thiophene methylamine, heat and continue stirring, cool, then pour crushed ice into the solution, stir, filter, wash, then vacuum dry, purify, recrystallize to obtain di(2-thiophene methyl)thiourea; Step a3: Mix bis(2-thiophenemethyl)thiourea, 3,4-ethylenedioxythiophene-anhydrous ethanol solution and deionized water, and sonicate to obtain solution A; Step a4: Mix sodium polystyrene sulfonate and deionized water, and stir magnetically to obtain solution B; Step a5: Mix ammonium persulfate, ferric chloride and deionized water, stir, and obtain solution C; Step a6: Pour solution B into solution A and sonicate. Then add solution C, stir, adjust the pH with hydrochloric acid, then evacuate and purge with nitrogen, stir, then repeat centrifugation and washing, adjust the solid content of the dispersion, and obtain a composite conductive aqueous dispersion.

2. The composite three-dimensional foil electrode material for aluminum electrolytic capacitors according to claim 1, characterized in that, The ratio of 1,1-thiocarbonyldiimidazole, anhydrous acetonitrile, and 2-thiophene methylamine in step a1 is 2.67-5.34 g : 75-150 mL : 1.66-3.32 mL.

3. The composite three-dimensional foil electrode material for aluminum electrolytic capacitors according to claim 1, characterized in that, In step a2, the ratio of the thiocarbonyl imidazole intermediate, anhydrous N,N-dimethylformamide, and 2-thiophene methylamine is 3-6 g: 75-150 mL: 1.33-2.66 mL; the amount of crushed ice is 80-100 g.

4. The composite three-dimensional foil electrode material for aluminum electrolytic capacitors according to claim 1, characterized in that, In step a3, the ratio of the amounts of bis(2-thiophenemethyl)thiourea, 3,4-ethylenedioxythiophene-anhydrous ethanol solution, and deionized water is 0.006-0.012 g : 0.32-0.64 mL : 10-20 mL; the 3,4-ethylenedioxythiophene-anhydrous ethanol solution is a solution prepared by mixing 3,4-ethylenedioxythiophene and anhydrous ethanol at a ratio of 1 g : 99 mL.

5. The composite three-dimensional foil electrode material for aluminum electrolytic capacitors according to claim 1, characterized in that, The ratio of sodium polystyrene sulfonate to deionized water in step a4 is 0.7-1.4g: 20-40mL.

6. The composite three-dimensional foil electrode material for aluminum electrolytic capacitors according to claim 1, characterized in that, The ratio of ammonium persulfate, ferric chloride, and deionized water used in step a5 is 0.72-1.44g: 0.001-0.002g: 10-20mL.

7. The composite three-dimensional foil electrode material for aluminum electrolytic capacitors according to claim 1, characterized in that, In step a6, the volume ratio of solution A, solution B, and solution C is 10-12 mL: 20-24 mL: 10-12 mL; the concentration of hydrochloric acid is 1 mol / L.

8. A method for preparing a composite three-dimensional foil electrode material for aluminum electrolytic capacitors, characterized in that, The preparation of the composite three-dimensional foil electrode material for aluminum electrolytic capacitors as described in any one of claims 1-7 includes the following steps: Step 1: Weigh out 50-60 parts by weight of aluminum powder, 40-50 parts by weight of ethylene glycol-water mixed solvent, 5-6 parts by weight of hydroxypropyl methylcellulose, 30-36 parts by weight of boric acid, 10-12 parts by weight of sodium borate, 1000-1200 parts by weight of deionized water, 15-20 parts by weight of zirconium oxychloride, 80-100 parts by weight of sealing solution, and 35-40 parts by weight of composite conductive aqueous dispersion, and set aside. Step 2: Mix aluminum powder, ethylene glycol-water mixed solvent and hydroxypropyl methylcellulose to obtain a slurry. Use a roller coater to coat the slurry on both sides of the base aluminum foil, then put it into a roller press to compact it. After drying, put it into a sintering furnace for sintering and cooling to obtain an aluminum foil with a three-dimensional porous aluminum powder sintered layer on the surface. Step 3: Cut the aluminum foil with the three-dimensional porous aluminum powder sintered layer on the surface into a sample, immerse it in anhydrous ethanol, ultrasonically clean it, then immerse it in pure water and ultrasonically clean it, then immerse it in dilute sulfuric acid solution, soak it at room temperature, rinse it, and blow it dry to obtain the pretreated three-dimensional foil substrate. Step 4: Add boric acid, sodium borate and deionized water to a beaker and stir. Add zirconium oxychloride, continue stirring, degas by sonication, and let stand to obtain the formation solution. Step 5: Pour the formation solution into the electrolytic cell, place the platinum electrode and the pretreated three-dimensional foil substrate, connect to the electrochemical workstation, turn on the constant temperature stirrer, and perform staged constant voltage formation. After the formation is completed, cool to obtain the composite dielectric layer composite three-dimensional foil. Step 6: Remove the composite dielectric layer composite three-dimensional foil from the electrolytic cell, rinse it, dry it, then transfer it to a muffle furnace for sintering, cool it, then immerse it in a sealing solution, soak it at room temperature, rinse it, and vacuum dry it to obtain the sealed composite dielectric layer composite three-dimensional foil. Step 7: Take the sealed composite dielectric layer composite three-dimensional foil, immerse it in anhydrous ethanol for ultrasonic cleaning, remove it and blow dry the surface with nitrogen gas. Pour the composite conductive aqueous dispersion into the material tank of the roller coating machine, adjust the cell depth of the micro-gravure roller, and coat the composite conductive aqueous dispersion onto the surface of the alumina dielectric layer through the roller coating roller. The coating is carried out in two stages, followed by drying, annealing, and cooling to obtain the composite three-dimensional foil electrode material.

9. The method for preparing a composite three-dimensional foil electrode material for aluminum electrolytic capacitors according to claim 8, characterized in that, The base aluminum foil in step two is a high-purity aluminum foil with a purity of ≥99.9% and a thickness of 10-20μm; the aluminum powder has a particle size of 1-10μm; and the ethylene glycol-water mixed solvent is a solution of ethylene glycol and deionized water mixed in a volume ratio of 1:

1.

10. The method for preparing a composite three-dimensional foil electrode material for aluminum electrolytic capacitors according to claim 8, characterized in that, The concentration of the dilute sulfuric acid solution in step three is 0.5 mol / L; the sealing solution in step six is ​​a 5 wt% aqueous solution of phosphoric acid.