Multi-layer composite aluminum foil capacitor with high charge capacity density

Abstract

The invention discloses a multi-layer composite aluminum foil capacitor with high charge capacity density, which is applied to the technical field of capacitors, and can store more charges in a limited area by optimizing an electrode material, improving an insulating medium and innovating a structural design, thereby effectively improving the charge capacity density of the capacitor. Compared with a traditional aluminum foil capacitor formed through corrosion, the charge capacity density of the capacitor is greatly improved, the requirements for miniaturization and portability of electronic equipment can be met, high-density ultrahigh-voltage-resistant electrolytic paper and reasonably-arranged dielectric thin films are adopted for isolating positive and negative electrode aluminum foils, the insulativity between electrodes is ensured, and the service life of the capacitor is prolonged. According to the utility model, the electrolytic paper is used for preventing the short circuit phenomenon, especially the electrolytic paper has the characteristics of high density and ultrahigh voltage resistance, so that the capacitor can stably work in a high-voltage environment, the reliable operation of the capacitor is guaranteed, meanwhile, the leakage current of the capacitor can be obviously reduced, and the stable performance of the capacitor in the long-term use process is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of capacitors, and in particular relates to a multilayer composite aluminum foil capacitor with high charge capacity density. Background Art

[0002] Aluminum foil capacitors are mainly composed of anode aluminum foil, cathode aluminum foil, dielectric and lead-out terminals. Their working principle is based on the basic electrical principle of capacitors, that is, when voltage is applied between the two plates of the capacitor (anode aluminum foil and cathode aluminum foil), the two plates will gather equal amounts of opposite charges respectively, thereby realizing the storage of electrical energy.

[0003] With the rapid development of modern science and technology, electronic equipment, electric vehicles, industrial automation equipment, etc. have increasingly higher performance requirements for capacitors. In many application scenarios, capacitors are required to have a high charge capacity density in order to store more charge in a limited volume to meet the equipment's needs for energy storage and fast charging and discharging. However, traditional multilayer composite aluminum foil capacitors often have certain limitations in charge capacity density and are difficult to meet the growing high performance requirements.

[0004] As for the electrode materials of the existing multilayer composite aluminum foil capacitors, the purity and surface structure of the aluminum foil have a great influence on the capacitance performance. Low-purity aluminum foil contains more impurities, which will increase the resistance and reduce the performance of the capacitor. At the same time, the traditional aluminum foil uses the electrochemical corrosion method to form holes on the surface of the aluminum foil using chemical solutions to increase its surface area, thereby obtaining a corrosion foil with a higher specific capacity, and then a layer of insulating dielectric oxide film is formed on its surface through chemical formation to obtain the positive electrode foil. The current practice of improving the specific capacity of aluminum foil by optimizing the electrochemical corrosion process has approached the theoretical limit and is difficult to meet the requirements of high charge capacity density.

[0005] Therefore, it is necessary to develop a new type of multilayer composite aluminum foil capacitor to solve the problems existing in the above-mentioned prior art and meet the needs of different fields for high charge capacity density capacitors. Summary of the invention

[0006] The purpose of the present invention is to propose a multilayer composite aluminum foil capacitor with high charge capacity density, which has the advantages of significantly improving the charge capacity density of the capacitor by optimizing electrode materials, improving insulating media and innovating structural design. Compared with traditional corrosion-formed aluminum foil capacitors, the charge capacity density of the capacitor of the present invention is greatly improved, which can meet the needs of miniaturization and portability of electronic equipment, and the high-purity aluminum foil electrodes and optimized insulating media can improve the performance stability of the capacitor, ensuring the stable performance of the capacitor during long-term use.

[0007] The above technical objectives of the present invention are achieved through the following technical solutions: a multilayer composite aluminum foil capacitor with high charge capacity density, comprising a guide pin, a positive aluminum foil, a negative aluminum foil, an electrolytic paper, an electrolyte, a dielectric film, an aluminum shell, colloid particles and an insulating sleeve, wherein the guide pin is riveted to the surface of the positive aluminum foil and the negative aluminum foil respectively, the electrolyte infiltrates the electrolytic paper, the positive aluminum foil and the negative aluminum foil are isolated by the electrolytic paper and the dielectric film, and the dielectric film is close to the positive aluminum foil, and is wound to form a capacitor core package structure, and is sealed by the colloid particles after being loaded into the aluminum shell to form a multilayer composite aluminum foil capacitor, and the insulating sleeve is formed on the surface of the aluminum shell by heat shrinkage; The positive electrode aluminum foil is made of high-purity aluminum foil, and its specific capacity is increased after surface treatment, and the negative electrode foil is made of a material with good electrical conductivity; The surface of the guide needle is treated and provided with an insulating protection structure; The dielectric film is made of polypropylene film material.

[0008] By adopting the above technical scheme, the charge capacity density of the capacitor is significantly improved by optimizing the electrode material, improving the insulating medium and innovating the structural design. Compared with traditional capacitors, the charge capacity density of the capacitor is greatly improved, which can meet the miniaturization and portability requirements of high-performance electronic devices. The high-purity aluminum foil electrodes and optimized insulating medium can improve the performance stability of the capacitor, and the use of composite insulating film and multi-layer insulation structure design can improve the voltage resistance and reliability of the capacitor, ensuring the stable performance of the capacitor during long-term use.

[0009] The present invention is further configured as follows: the purity of the high-purity aluminum foil is above 99.999%, and a stable three-dimensional structure is formed on its surface by coating and sintering technology, thereby greatly improving the specific volume of the aluminum foil.

[0010] By adopting the above technical solution, through the use of high-purity aluminum foil, it is possible to ensure a low impurity content in the electrode, which can reduce resistance and thus improve capacitor performance. At the same time, a three-dimensional structure is established on the surface of the high-purity aluminum foil, so that the positive electrode aluminum foil can store more charge in a limited area, thereby greatly improving the charge storage capacity and laying the foundation for high charge capacity density.

[0011] The present invention is further configured as follows: the positive electrode aluminum foil and the negative electrode aluminum foil use high specific volume and high bending double composite positive electrode foil and double composite negative electrode foil, and the positive electrode aluminum foil and the aluminum negative electrode foil are isolated by high-density ultra-high voltage-resistant electrolytic paper.

[0012] By adopting the above technical scheme, by using high-specific-capacity and high-bend double-composite positive foil and double-composite negative foil for the positive aluminum foil and the negative aluminum foil, the electrode material has good conductivity while further improving the specific capacity of the electrode, which helps to increase the charge capacity density of the capacitor. The high-density and ultra-high-voltage electrolytic paper is used as isolation. While ensuring good conductivity between the electrodes, the isolation effect is enhanced, which can effectively prevent short circuits between the electrodes under complex working conditions such as high voltage and high current, ensuring that the capacitor can operate stably in various harsh electrical environments, and expanding the application range of the capacitor.

[0013] The present invention is further configured as follows: the positive electrode aluminum foil is processed into aluminum powder (or aluminum particles) with a diameter of 10 to 40 microns by atomization, ball milling or mechanical crushing method, and ethylene glycol and N-methyl-2-pyrrolidone are used as solvents, polyvinylidene fluoride is used as an adhesive, and mixed with aluminum powder to obtain aluminum powder slurry; the aluminum powder slurry is uniformly coated on the surface of the aluminum foil, and then the solvent and adhesive therein are removed by high-temperature sintering to obtain a high-specific volume aluminum foil, which is chemically formed to obtain a high-specific volume multilayer composite aluminum foil as the positive electrode foil.

[0014] By adopting the above technical scheme and preparing the positive electrode aluminum foil, the microstructure and performance of the positive electrode aluminum foil can be accurately controlled, so that the specific capacity of the positive electrode aluminum foil is significantly improved, thereby effectively increasing the charge capacity density of the capacitor, meeting the needs of modern electronic equipment, new energy equipment, etc. for high charge capacity density capacitors.

[0015] The present invention is further configured as follows: the aluminum shell is aluminum with a purity of 98.5%, and the rubber particles are high temperature resistant peroxide-cured hydrogenated nitrile rubber.

[0016] By adopting the above technical scheme, by selecting aluminum shell with 98.5% purity as packaging material, aluminum of this purity has a certain mechanical strength, which can provide effective physical protection for the internal components of the capacitor, resist external mechanical impact, collision, etc., and prevent internal components from being damaged. It also has good conductivity and can play a certain role in some application scenarios such as electromagnetic shielding to ensure the stable operation of the capacitor in a complex electromagnetic environment. The rubber particles use high-temperature resistant peroxide-cured hydrogenated nitrile rubber as a sealing material. Due to its good sealing performance, it can maintain a sealing effect in a high temperature environment, effectively prevent electrolyte leakage and external moisture, dust, etc. from entering the capacitor, maintain the stability of the internal chemical environment of the capacitor, and ensure the normal operation of the capacitor. This reliable sealing material cooperates with the aluminum shell to form a complete packaging system, so that the capacitor can operate stably in a complex working environment, extend the service life of the capacitor, reduce the risk of capacitor failure due to external factors, and reduce equipment maintenance costs.

[0017] The present invention is further configured as follows: the thickness of the positive electrode aluminum foil is 10-20 microns, and the thickness of the negative electrode aluminum foil is 5-15 microns.

[0018] By adopting the above technical scheme, the thickness of the positive aluminum foil and the negative aluminum foil is reasonably set, so that they can work together better in terms of conductivity, charge storage capacity, etc.; the higher specific capacity of the positive aluminum foil combined with the appropriate thickness can store charges efficiently; the good conductivity of the negative aluminum foil is matched with the relatively thin thickness, which can conduct charges in a timely manner. The two cooperate with each other to ensure the smooth charging and discharging process of the capacitor, and improve the working efficiency and performance stability of the capacitor.

[0019] The present invention is further configured as follows: the three-dimensional structure of the high-purity aluminum foil is a honeycomb, mesh or foam structure, and its porosity is between 50% and 80%.

[0020] By adopting the above technical solution, the specific volume enhancement effect of aluminum foil is further increased through a specific three-dimensional structure. Compared with aluminum foils of other ordinary structures, it can store more charge with the same amount of material, thereby significantly improving the charge capacity density of the capacitor, making the capacitor perform better in application scenarios with high requirements for energy storage.

[0021] The present invention is further configured as follows: the surface treatment of the guide needle is one of gold plating, silver plating or nickel plating, and the insulating protection structure arranged on the surface of the guide needle is one of a silicone sleeve, a plastic shell or an epoxy resin coating.

[0022] By adopting the above technical solution, the conductivity and corrosion resistance of the guide needle can be improved through surface treatment of the guide needle, thereby extending the service life of the capacitor, while the provision of the insulating protection structure can prevent the guide needle from contacting the external environment, thereby improving the reliability and safety of the capacitor.

[0023] The present invention is further configured such that the withstand voltage of the capacitor after being encapsulated in an aluminum shell is not less than 1.5 times of its rated voltage.

[0024] By adopting the above technical solution, a good packaging method can be used to ensure the sealing and reliability of the capacitor, improve the voltage resistance performance, ensure the safety and stability during use, and reduce the risk of capacitor damage due to excessive voltage.

[0025] The present invention is further configured as follows: the thickness of the dielectric film is 3 to 8 microns, and the number of alternating layers of the dielectric film is not less than three.

[0026] By adopting the above technical scheme, the energy storage capacity of the dielectric film can be further improved on the basis of ensuring good insulation performance through the design of the dielectric film thickness and the stacking method. The thinner thickness allows more dielectric film layers to be accommodated in a limited space, thereby increasing the capacitance value of the capacitor; and the alternating stacking of not less than three layers synergistically improves the overall performance of the capacitor through the insulation and energy storage effects of the multiple layers, so that the capacitor can store and release electrical energy more efficiently during the charging and discharging process, thereby improving the working efficiency and charge capacity density of the capacitor.

[0027] In summary, the present invention has the following beneficial effects: 1. By optimizing the electrode material and improving the electrode preparation process, the charge capacity density of the capacitor is significantly improved. Compared with the traditional aluminum foil capacitor, its charge capacity density is increased several times, which can meet the needs of miniaturization of high-performance electronic devices. In addition, the high-purity aluminum foil electrode can improve the performance stability of the capacitor; 2. The use of high-density and ultra-high voltage-resistant electrolytic paper and reasonably arranged dielectric films to isolate the positive and negative aluminum foils ensures the insulation between the electrodes and prevents short circuits. In particular, the high density and ultra-high voltage-resistant characteristics of the electrolytic paper enable it to work stably in a high voltage environment, providing a guarantee for the reliable operation of the capacitor. At the same time, it can significantly reduce the leakage current of the capacitor, ensuring the stable performance of the capacitor during long-term use. DETAILED DESCRIPTION

[0029] A multilayer composite aluminum foil capacitor with high charge capacity density comprises a guide pin, a positive aluminum foil, a negative aluminum foil, electrolytic paper, an electrolyte, a dielectric film, an aluminum shell, colloidal particles and an insulating sleeve. The positive aluminum foil is prepared by: processing high-purity aluminum into aluminum powder (or aluminum particles) with a diameter of 10 to 40 microns by atomization, ball milling or mechanical crushing method; using ethylene glycol and N-methyl-2-pyrrolidone as solvents and polyvinylidene fluoride as an adhesive to mix with aluminum powder to obtain aluminum powder slurry; uniformly coating the aluminum powder slurry on the surface of the aluminum foil, and then removing the solvent and adhesive therein by high-temperature sintering to obtain a high-specific-capacity aluminum foil; performing a chemical treatment on the obtained high-specific-capacity aluminum foil, further optimizing the performance of the aluminum foil by the chemical treatment, obtaining a high-specific-capacity multilayer composite aluminum foil as a positive foil after chemical treatment, and establishing a three-dimensional structure on the surface of the high-purity aluminum foil so that the positive aluminum foil can Store more charge in a limited area, thereby greatly improving the charge storage capacity and laying the foundation for high charge capacity density. Preparation of negative electrode aluminum foil: Select aluminum materials with a purity between 98% and 99.5%, and process them into aluminum foil with thickness that meets the requirements through conventional processing methods such as rolling. During the rolling process, the rolling pressure and the number of rolling times must be strictly controlled. The rolling pressure is set between 5 and 10 MPa. The number of rolling times is adjusted according to the thickness of the initial aluminum block and the desired final aluminum foil thickness. It needs to be rolled 3 to 5 times to ensure that the thickness of the negative electrode aluminum foil is uniform and meets the requirements. High-density and ultra-high voltage-resistant electrolytic paper is used to isolate the positive and negative aluminum foils. Selection and preparation of electrolytic paper: Select high-density and ultra-high voltage-resistant electrolytic paper to ensure that it can meet the requirements for the isolation of the positive and negative aluminum foils of the capacitor. Select a density of 0.8-1.2 g / cm 3Electrolytic paper with a withstand voltage of not less than 500-800V / mm and a porosity of 20%-40%; before use, the electrolytic paper must be pretreated and cut into rectangular sheets with a length of 5-10cm and a width of 3-5cm to ensure that it can perfectly match the positive aluminum foil, negative aluminum foil and dielectric film and other components to play an effective isolation role in the capacitor. The thickness of the dielectric film is 3-8 microns, and the number of alternating layers of the dielectric film is not less than three. Preparation of the dielectric film: Select polypropylene film material to ensure that its thickness is in the range of 3-8 microns, and select a dielectric constant of 2.2- 2.6, the insulation strength is not less than 100-200V / μm, and the polypropylene film has good flexibility; according to the design size of the capacitor core package, the polypropylene film is cut into a circular sheet, the diameter of which is slightly larger than the diameter of the capacitor core package and is controlled at 2.2-3.2cm to ensure that the corresponding parts can be completely covered during the winding process, and each layer of film can overlap well to meet the requirement of alternating stacking number of not less than three layers. The positive aluminum foil and the negative aluminum foil are isolated by electrolytic paper and dielectric film, and the dielectric film is close to the positive aluminum foil. The capacitor core package structure is wound, and the prepared double composite positive aluminum foil and double composite negative aluminum foil are placed. The foil, electrolytic paper and dielectric film are wound in the prescribed order and manner to form a capacitor core package structure. During the winding process, attention should be paid to the arrangement order and tightness of each component to ensure the stability and integrity of the capacitor core package structure; first, a layer of dielectric film is placed flat on the winding workbench to ensure that its surface is flat and wrinkle-free, and then the cut electrolytic paper is placed on the dielectric film. The placement direction of the electrolytic paper should be consistent with the long side direction of the dielectric film. Then the negative aluminum foil is placed on the electrolytic paper. The placement of the negative aluminum foil should ensure that its long side is parallel to the long side of the electrolytic paper, and the edge of the negative aluminum foil should be aligned with the edge of the electrolytic paper to ensure that it is wound around. The components can be tightly combined in the process; then, place another layer of dielectric film on the negative aluminum foil, and also ensure that its surface is flat and wrinkle-free, and aligned with the dielectric film below, and then place the positive aluminum foil on this layer of dielectric film. The placement requirements of the positive aluminum foil are similar to those of the negative aluminum foil. Ensure that its long side is parallel to the long side of the dielectric film, and the edge is aligned with the edge of the dielectric film; repeat the placement of electrolytic paper, dielectric film, negative aluminum foil and positive aluminum foil in the above order. According to the design requirements, ensure that the number of alternating layers of dielectric film is not less than three. After each layer is placed, gently press the components to make them tightly combined;Finally, use a special winding device to wind these components in the specified direction. The speed of the winding device is set at 10-20 rpm. During the winding process, the winding situation should be observed in real time to ensure that the components will not shift or wrinkle during the winding process, forming a stable capacitor core package structure. After being placed in an aluminum shell, it is sealed with rubber particles. High-temperature resistant peroxide-cured hydrogenated nitrile rubber is used as rubber particles to seal the aluminum shell. During the sealing process, it is necessary to ensure that the rubber particles fit tightly with the aluminum shell to prevent leakage of electrolyte and external moisture, dust, etc. from entering the capacitor. First, cut the rubber particles according to the shape and size of the aluminum shell to ensure that the cut rubber particles can completely cover the aluminum shell. The opening part of the rubber pellet is then coated with a proper amount of glue (such as special rubber glue) on one side of the rubber pellet, and the side coated with glue is fitted with the opening edge of the aluminum shell. Press hard to ensure that the rubber pellet and the aluminum shell are tightly fitted without bubbles. Then the aluminum shell and the rubber pellet are placed in a special vulcanization equipment, and the vulcanization temperature is set between 150℃-200℃. The vulcanization time can be set to 1-3 hours. During the vulcanization process, the temperature is ensured to be stable through the temperature control system of the vulcanization equipment, so that the rubber pellet is fully vulcanized to form a good sealing effect, thereby forming a multi-layer composite aluminum foil capacitor. The capacitor encapsulated in the aluminum shell is tested to ensure that its withstand voltage value is not less than 1.5 times its rated voltage. The guide pins are riveted to the positive aluminum foil respectively. and the surface of the negative electrode aluminum foil, and treat the surface of the guide needle, select one of the treatment methods of gold plating, silver plating or nickel plating to improve the conductivity and anti-oxidation properties of the guide needle. If gold plating is selected, gold can be plated on the surface of the guide needle by electroplating. First, put the guide needle into a special electroplating tank containing a gold plating solution, set the electroplating current to between 0.1-0.3A, and set the electroplating time to between 10-20 minutes. During the electroplating process, the control system of the electroplating equipment should be used to ensure that the electroplating current is stable, so that gold is evenly plated on the surface of the guide needle to improve the conductivity and anti-oxidation properties of the guide needle. If silver plating is selected, the guide needle is also placed in a plating tank containing a silver plating solution, and the electroplating current is set to 0. 1-0.3A, the electroplating time can be set to 10-20 minutes, and silver is evenly plated on the surface of the guide pin by electroplating, which plays a role in improving conductivity and anti-oxidation. For nickel plating, the guide pin is placed in an electroplating tank containing a nickel plating solution (, and the electroplating current is set between 0.1-0.3A. The electroplating time can be set to 10-20 minutes. Nickel is evenly plated on the surface of the guide pin by electroplating to improve the performance of the guide pin, and an insulating protective structure in a silicone sleeve, a plastic shell or an epoxy resin coating is formed on the surface of the guide pin by heat shrinking. Professional heat shrinking equipment can be used to ensure that the insulating sleeve fits tightly with the aluminum shell, further enhancing the insulation performance of the capacitor;First, select an insulating sleeve of appropriate size, whose inner diameter should be slightly larger than the outer diameter of the aluminum shell so that it can be smoothly put on the aluminum shell. Then put the insulating sleeve on the aluminum shell to ensure that it covers the entire surface of the aluminum shell. Then use a heat shrink device to heat shrink the insulating sleeve. Set the heat shrink temperature to between 120℃-150℃ and the heat shrink time to 2-5 minutes. During the heat shrink process, observe the shrinkage of the insulating sleeve to ensure that it fits tightly with the aluminum shell to form a complete insulating protective layer. ;

[0030] Among them, the preparation steps of positive electrode aluminum foil are as follows: processing of high-purity aluminum powder: first, prepare the operation of converting high-purity aluminum into aluminum powder according to a predetermined processing method. For the atomization method, high-purity aluminum with a purity of more than 99.999% needs to be placed in a special heating container. By accurately controlling the heating temperature and time, the high-purity aluminum is heated to a liquid state. The heating temperature can be set between 660°C and 700°C. This temperature range can ensure that the aluminum is fully melted and maintains good fluidity. Then, high-pressure gas (such as nitrogen or argon) is used to spray the liquid aluminum into tiny aluminum powder particles through a special nozzle. During the spraying process, the pressure of the high-pressure gas must be strictly controlled. Usually, the pressure can be set between 5-10MPa to ensure that the diameter of the generated aluminum powder particles is evenly distributed between 10-40 microns; When using the ball milling method, a high-purity aluminum block needs to be placed in a ball mill and an appropriate amount of grinding media is added. The speed of the ball mill should be adjusted according to the size of the aluminum block and the desired grinding effect. The speed can be set at 100-300 rpm. During the ball milling process, the machine should be stopped regularly to check the particle size of the aluminum powder to ensure that after 2-5 hours of ball milling, aluminum powder particles with a diameter of 10-40 microns that meet the requirements can be obtained; for the mechanical crushing method, the high-purity aluminum block is also placed in a special mechanical crusher, and the aluminum block is cut and crushed by the high-speed rotation of the tool inside the crusher. During the crushing process, the tool speed can be set at 200-500 rpm, and the cutting force can be fine-tuned according to factors such as the hardness of the aluminum block to ensure the generation of uniform aluminum powder particles with a diameter within the range of 10-40 microns.

[0031] Preparation of aluminum powder slurry: After obtaining suitable aluminum powder, the next step is to prepare aluminum powder slurry. Ethylene glycol is used as a solvent. The amount used should be accurately calculated based on the amount of aluminum powder and the final desired slurry concentration. The mass ratio of ethylene glycol to aluminum powder can be set between 2:1-3:1. At the same time, N-methyl-2-pyrrolidone is added as an auxiliary solvent. The amount used is relatively small compared to ethylene glycol. The volume ratio of ethylene glycol to N-methyl-2-pyrrolidone can be 5:1-10:1. Then, polyvinylidene fluoride is added to the mixed system as a binder. The amount of polyvinylidene fluoride should ensure that the aluminum powder can be evenly dispersed in the slurry and has good adhesion. The mass ratio of polyvinylidene fluoride to aluminum powder can be set between 0.1:1-0.3:1. The above three components are placed in a special mixing container. A planetary agitator with a strong stirring function can be used. Stir at a low speed for 5-10 minutes to make the components preliminarily mixed evenly, then gradually increase the stirring speed to 500-1000 rpm, and continue stirring for 20-30 minutes to ensure that the components are fully mixed and evenly mixed to obtain aluminum powder slurry; Aluminum foil surface coating: After preparing the aluminum powder slurry, start to evenly coat it on the surface of the aluminum foil. There are many coating methods, such as spraying or brushing. If you choose the spraying method, you need to use professional spraying equipment to load the aluminum powder slurry into the material tank of the spray gun. Before spraying, you need to debug the spraying equipment and set the appropriate spraying pressure and flow rate. The spraying pressure can be set between 0.2-0.5MPa, and the spraying flow rate can be adjusted according to the area of ​​the aluminum foil and the desired coating thickness. It can be set at 5-10mL / min. During the spraying process, keep the distance between the spray gun and the surface of the aluminum foil uniform, and the distance can be set between 15-20cm to ensure uniform coating thickness. For the brushing method, choose a suitable brush, dip the aluminum powder slurry on the brush, and then brush it on the surface of the aluminum foil in a certain direction and order. During the brushing process, pay attention to avoid missing brushes or over-thick brushing. The amount of slurry dipped each time should be moderate to ensure that a uniform coating layer is formed on the entire aluminum foil surface.

[0032] High-temperature sintering and chemical formation treatment: Put the aluminum foil coated with slurry into a high-temperature furnace for sintering. Before putting it in, make sure that the high-temperature furnace has been preheated to the appropriate temperature. The preheating temperature can be set between 500℃-600℃. Then put the aluminum foil into the high-temperature furnace and set the sintering temperature between 800℃-900℃. The sintering time is adjusted according to factors such as the thickness and coating amount of the aluminum foil. It can usually be set to 1-3 hours. During the sintering process, the temperature in the high-temperature furnace must be kept stable and accurately monitored and adjusted by the temperature control system; after high-temperature sintering, the solvent and adhesive on the surface of the aluminum foil will be removed to obtain a high-specific volume aluminum foil. Next, the high-specific volume aluminum foil is subjected to chemical formation treatment. The chemical formation treatment can be carried out in a special chemical formation equipment. The chemical formation voltage is set between 3-5V and the chemical formation time can be set to 2-4 hours. Through the chemical formation treatment, the performance of the aluminum foil is further optimized, and a high-specific volume multi-layer composite aluminum foil is obtained as the positive electrode foil after chemical formation.

[0033] In order to more intuitively demonstrate the advantages of the multilayer composite aluminum foil capacitor with high charge capacity density of the present invention compared with the traditional capacitor, the following is a detailed data comparison table of the key performance indicators of the two: Charge capacity density: The multilayer composite aluminum foil capacitor with high charge capacity density of the present invention adopts a positive aluminum foil with high specific capacity to form a stable three-dimensional structure on the surface of a high-purity aluminum foil through a special preparation process and a reasonable overall structural design (including the configuration of electrodes, dielectric films, etc.), so that the charge capacity density of the capacitor of the present invention is significantly improved to 80-200 μF / cm 3 This allows more charge to be stored in a limited volume, better meeting the needs of modern electronic devices, new energy devices, etc. for high charge capacity density capacitors.

[0034] specific volume: The multilayer composite aluminum foil capacitor with high charge capacity density of the present invention greatly improves the specific capacity of the aluminum foil by virtue of a unique positive electrode aluminum foil preparation method (processing high-purity aluminum into aluminum powder of a specific diameter and preparing it into a slurry coating and sintering process, etc.). The specific capacity of the capacitor of the present invention can reach 500-1000 μF / g, which indicates that under the condition of the same mass of electrode material, the capacitor of the present invention can store more charge, further reflecting its advantage in charge storage.

[0035] Withstand voltage: The multi-layer composite aluminum foil capacitor with high charge capacity density of the present invention, after being encapsulated in an aluminum shell, has a withstand voltage value of not less than 1.5 times its rated voltage. If the rated voltage is 50V, the withstand voltage value is not less than 75V. This higher withstand voltage capability enables the capacitor to work stably in higher voltage application scenarios, such as the power system of electric vehicles, the high voltage working environment of industrial automation equipment, etc., reducing the risk of capacitor damage due to excessive voltage.

[0036] Equivalent series resistance: The multilayer composite aluminum foil capacitor with high charge capacity density of the present invention can reduce the equivalent series resistance of the capacitor to 3-10 mΩ by optimizing the design of electrode materials, structure, packaging, etc. The lower equivalent series resistance means less energy loss during the charging and discharging process, and can more efficiently store and release electric energy, thereby improving the working efficiency of the capacitor in the circuit.

[0037] Operating temperature range: The multilayer composite aluminum foil capacitor with high charge capacity density of the present invention adopts suitable materials (such as high temperature resistant colloid particles, dielectric films with good thermal stability, etc.) and a reasonable packaging structure. The capacitor of the present invention can maintain stable performance in a wider temperature range, and its operating temperature range can reach -40-105°C, which enables the capacitor to adapt to more diverse working environments, including some extreme temperature environments, such as low temperature environments in the aerospace field or industrial high temperature environments.

[0038] Short circuit failure rate between electrodes: The multilayer composite aluminum foil capacitor with high charge capacity density of the present invention adopts high-density ultra-high voltage-resistant electrolytic paper and reasonably arranged dielectric films to isolate the positive and negative aluminum foils, and cooperates with a reliable packaging structure to effectively prevent the occurrence of short circuits between electrodes. The short circuit failure rate between electrodes of the capacitor of the present invention can be reduced to 1-3 per million hours, which shows that the capacitor of the present invention has higher reliability during long-term use and can reduce the risk of equipment failure caused by short circuits between electrodes.

[0039] Service life: The multilayer composite aluminum foil capacitor with high charge capacity density of the present invention has the advantages mentioned above, such as high charge capacity density, good voltage resistance, reliable packaging and insulation protection, etc. The service life of the capacitor of the present invention can be extended to 5000-10000 hours. The longer service life means that when used in the equipment, the capacitor does not need to be replaced frequently, which reduces the maintenance cost and downtime of the equipment and improves the overall operation efficiency of the equipment.

[0040] It can be clearly seen from the above data comparison that the multilayer composite aluminum foil capacitor with high charge capacity density of the present invention is superior to traditional capacitors in multiple key performance indicators, has broader application prospects and higher practical value, and compared with traditional corrosion-formed aluminum foil capacitors, the charge capacity density of the capacitor is greatly improved, which can meet the needs of miniaturization and portability of electronic equipment.

[0041] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A multilayer composite aluminum foil capacitor with high charge capacity density, comprising a guide pin, a positive aluminum foil, a negative aluminum foil, an electrolytic paper, an electrolyte, a dielectric film, an aluminum shell, colloid particles and an insulating sleeve, characterized in that: The guide pins are riveted to the surfaces of the positive aluminum foil and the negative aluminum foil respectively, the electrolyte infiltrates the electrolytic paper, the positive aluminum foil and the negative aluminum foil are isolated by the electrolytic paper and the dielectric film, and the dielectric film is close to the positive aluminum foil, and the capacitor core package structure is wound to form a capacitor core package structure, and then sealed by the colloid particles after being loaded into the aluminum shell to form a multi-layer composite aluminum foil capacitor, and the insulating sleeve is heat-shrunk to form on the surface of the aluminum shell; The positive electrode aluminum foil is made of high-purity aluminum foil, and its specific capacity is increased after surface treatment, and the negative electrode foil is made of a material with good electrical conductivity; The surface of the guide needle is treated and provided with an insulating protection structure; The dielectric film is made of polypropylene film material.

2. The multilayer composite aluminum foil capacitor with high charge capacity density according to claim 1, characterized in that: The purity of the high-purity aluminum foil is above 99.999%, and a stable three-dimensional structure is formed on its surface by coating and sintering technology, thereby greatly improving the specific volume of the aluminum foil.

3. The multilayer composite aluminum foil capacitor with high charge capacity density according to claim 1, characterized in that: The positive electrode aluminum foil and the negative electrode aluminum foil use high specific volume and high bending double composite positive electrode foil and double composite negative electrode foil, and the positive electrode aluminum foil and the negative electrode aluminum foil are isolated by high-density ultra-high voltage-resistant electrolytic paper.

4. The multilayer composite aluminum foil capacitor with high charge capacity density according to claim 1, characterized in that: The positive electrode aluminum foil is processed from high-purity aluminum into aluminum powder (or aluminum particles) with a diameter of 10 to 40 microns by an atomization method, a ball milling method or a mechanical crushing method, and ethylene glycol and N-methyl-2-pyrrolidone are used as solvents, and polyvinylidene fluoride is used as a binder to mix with aluminum powder to obtain aluminum powder slurry; the aluminum powder slurry is evenly coated on the surface of the aluminum foil, and then the solvent and the binder are removed by high-temperature sintering to obtain a high-specific volume aluminum foil, which is then chemically formed to obtain a high-specific volume multilayer composite aluminum foil as the positive electrode foil.

5. The multilayer composite aluminum foil capacitor with high charge capacity density according to claim 1, characterized in that: The aluminum shell is made of aluminum with a purity of 98.5%, and the rubber particles are high-temperature resistant peroxide-cured hydrogenated nitrile rubber.

6. The multilayer composite aluminum foil capacitor with high charge capacity density according to claim 1, characterized in that: The thickness of the positive electrode aluminum foil is 10-20 microns, and the thickness of the negative electrode aluminum foil is 5-15 microns.

7. The multilayer composite aluminum foil capacitor with high charge capacity density according to claim 2, characterized in that: The three-dimensional structure of the high-purity aluminum foil is a honeycomb, mesh or foam structure, and its porosity is between 50% and 80%.

8. The multilayer composite aluminum foil capacitor with high charge capacity density according to claim 1, characterized in that: The surface treatment of the guide pin is one of gold plating, silver plating or nickel plating, and the insulating protection structure arranged on the surface of the guide pin is one of a silicone sleeve, a plastic shell or an epoxy resin coating.

9. The multilayer composite aluminum foil capacitor with high charge capacity density according to claim 1, characterized in that: The withstand voltage of the capacitor encapsulated in an aluminum shell shall not be less than 1.5 times its rated voltage.

10. The multilayer composite aluminum foil capacitor with high charge capacity density according to claim 1, characterized in that: The thickness of the dielectric film is 3-8 microns, and the number of alternating layers of the dielectric film is not less than three.

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