Organic chip-style solid tantalum electrolytic capacitor and preparation method therefor

Abstract

An organic chip-style solid tantalum electrolytic capacitor preparation method, comprising the following steps: obtaining tantalum powder and pressing into a tantalum block, and then sintering in a vacuum; impregnating the sintered block with an anodization formation liquid, boil-cleaning in a high-temperature steam environment, carrying out vacuum annealing, and subsequently impregnating with the original anodization formation liquid and applying a direct-current voltage to obtain a tantalum core; impregnating the tantalum core with a silane coupling agent aqueous solution, drying, repeatedly immersing the tantalum core into a conductive polymer slurry, drying, coating a graphite layer and a silver paste layer, and then packaging to obtain the organic chip-style solid tantalum electrolytic capacitor. The cycling stability of the capacitor is improved by means of the conductive polymer slurry; additionally, by utilizing a low-temperature formation method, subsequently placing same in a high-temperature steam environment and boil-cleaning, placing same in a nitrogen atmosphere and annealing, and then impregnating the surface of a tantalum pentoxide layer with the silane coupling agent, the stability of the tantalum pentoxide layer is effectively improved, and the durability of the capacitor in high-temperatures is improved.

Description

An organic chip solid tantalum electrolytic capacitor and its preparation method Technical Field

[0001] The present invention belongs to the technical field of tantalum capacitors, and in particular relates to an organic chip-type solid tantalum electrolytic capacitor and a preparation method thereof. Background Art

[0002] As an indispensable passive electronic component in electronic circuits, capacitors have important applications in filtering, bypassing, coupling, and other aspects. Among the many types of capacitors, tantalum electrolytic capacitors have excellent performance such as high reliability and low leakage current, and are widely used in cutting-edge fields such as national defense and aerospace. Solid tantalum electrolytic capacitors were first successfully developed by Bell Laboratories in the United States in 1956. They have excellent performance and are the smallest of all capacitors with the largest capacity. Chip tantalum electrolytic capacitors adopt a chip structure and plastic packaging. They have the advantages of small size, light weight, low leakage current and high reliability. They have become the inevitable new direction of mainstream development in the tantalum electrolytic capacitor industry and are one of the indispensable core components of the new generation of high-precision and cutting-edge weapons and equipment.

[0003] Tantalum electrolytic capacitors use a tantalum metal block as the anode. The sintered tantalum anode is placed in an energy-enhancing tank, where a uniform oxide film, tantalum pentoxide, forms on the surface. Manganese dioxide or a conductive polymer, produced by the high-temperature decomposition of a manganese nitrate solution, serves as the electrolyte. Carbon and silver serve as the cathode, and the electrical energy is extracted through leads. With the successful application of new-generation semiconductor technology, market demand for high-voltage organic chip solid tantalum electrolytic capacitors is growing exponentially. Technical issues

[0004] In existing technology, solid-state electrolytic capacitors often use conductive polymers (such as polyaniline, polypyrrole, polythiophene, and polyacetylene) as electrolytes, primarily due to their advantages such as simple synthesis and good stability. However, the conductivity of pure conductive polymers is not high, and during the capacitor's charge and discharge cycles, the conductive polymer expands and contracts, causing the polymer chain to break, resulting in a decrease in the conductive polymer's conductivity, which does not meet the requirements of solid-state tantalum electrolytic capacitors. In addition, organic chip-type solid tantalum electrolytic capacitors have poor stability in high-temperature environments and are generally still limited to use in environments between 55 and 105°C. Technical Solutions

[0005] To address the deficiencies mentioned in the above-mentioned background technology, the present invention aims to provide an organic chip solid tantalum electrolytic capacitor and a preparation method thereof. The cycling stability of the capacitor is improved by synthesizing a conductive polymer slurry. In addition, by adopting a low-temperature chemical method, followed by boiling and washing in a high-temperature steam environment and annealing in a nitrogen environment, and before coating with the conductive polymer slurry, the surface of the tantalum pentoxide dielectric layer is impregnated with an aqueous solution of a silane coupling agent, thereby effectively improving the stability of the tantalum pentoxide dielectric and enhancing the capacitor's ability to withstand long-term high temperatures.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing an organic chip solid tantalum electrolytic capacitor comprises the following steps:

[0008] S1, take tantalum powder and press it into tantalum blocks with tantalum wire leads. -4 ~1×10 -3 Sintering at 1300-1550°C for 25-40 min under Pa vacuum conditions, then breaking the vacuum when the temperature drops to 60-80°C to obtain a sintered block;

[0009] S2. The sintered block is immersed in an energizing forming liquid at 5-15°C to form an amorphous dielectric, washed in a high-temperature steam environment at 100-120°C, and then vacuum annealed. Then, the sintered block is immersed in the original energizing forming liquid at 60-80°C and a DC voltage is applied. The constant voltage is maintained for 2-4 hours, and then washed with deionized water for 10-60 minutes to remove the residual energizing forming liquid, thereby obtaining a tantalum core with a dielectric oxide film formed thereon.

[0010] S3, dipping the tantalum core in a silane coupling agent aqueous solution for 10 to 20 minutes, drying it in an oven after dipping, and then repeatedly dipping it in a conductive polymer slurry and drying it in an oven to obtain a cathode-coated anode tantalum core assembly structure;

[0011] S4. Coating the cathode-wrapped anode tantalum core assembly structure with a graphite layer, and then coating the outer layer with a cathode-leaded silver paste layer, and encapsulating it to prepare an organic chip-type solid tantalum electrolytic capacitor.

[0012] Preferably, the method of pressing tantalum powder into tantalum blocks in step S1 is specifically as follows: selecting tantalum powder with a specific capacity corresponding to the capacitor voltage, adding camphor and mixing evenly to form a mixed powder; after the mixed powder is dried, pressing it into tantalum blocks of corresponding size, wherein the camphor is a mixture of camphor powder and anhydrous ethanol.

[0013] Preferably, the energy-forming liquid in step S2 is phosphoric acid, and the mass fraction of the energy-forming liquid is 0.1-2%.

[0014] Preferably, the vacuum annealing temperature in step S2 is 250° C. to 450° C., and the vacuum annealing time is 30-60 min.

[0015] 5. The method for preparing an organic chip solid tantalum electrolytic capacitor according to claim 1, wherein in step S2, the DC voltage is 0.6 to 1.5 times the rated DC voltage, and the current density is 20 to 60 mA / g.

[0016] Preferably, the silane coupling agent in step S3 is γ-aminopropyltriethoxysilane, and the mass fraction of the silane coupling agent is 0.5-1%.

[0017] Preferably, the method for preparing the conductive polymer slurry in step S3 comprises the following steps:

[0018] A. Graphene oxide was added to deionized water for ultrasonic dispersion, and then polysorbate 20 was added. The mixture was stirred for 5-7 hours. After centrifugation and washing, the reaction product was added to deionized water, and glycine was added. The mixture was reacted at room temperature for 10-12 hours, and then refluxed in an oil bath at 110-135°C for 20-24 hours. The mixture was washed and dried to obtain modified graphene.

[0019] B. Take the modified graphene and add it to deionized water for ultrasonic dispersion to obtain a modified graphene dispersion, add hydrochloric acid to adjust the pH of the dispersion to 3-4, then add 3,4-ethylenedioxythiophene monomer, ultrasonically oscillate for 15-30 minutes to obtain a mixed solution, take ammonium persulfate and ferric sulfate, dissolve them in deionized water, and then add them to the mixed solution, react at room temperature under nitrogen protection for 20-24 hours, and filter with 200 mesh gauze after the reaction to obtain a conductive polymer slurry.

[0020] Preferably, in step A, the addition ratio of graphene oxide, deionized water, polysorbate 20, deionized water and glycine is 0.5 g: 450-500 mL: 0.7-1.2 g: 180-220 mL: 2.2-3 g.

[0021] Preferably, in step B, the addition ratio of modified graphene, deionized water, 3,4-ethylenedioxythiophene, ammonium persulfate, ferric sulfate, and deionized water is 0.1 g: 90-110 mL: 0.1-0.3 g: 0.2-0.5 g: 0.0005-0.0015 g: 20-60 mL.

[0022] An organic chip-type solid tantalum electrolytic capacitor is made by any of the above-mentioned preparation methods. Beneficial effects

[0023] Beneficial effects of the present invention:

[0024] The present invention utilizes oxygen-containing functional groups on the surface of polysorbate-20 to be grafted with oxygen-containing functional groups on the surface of graphene oxide through hydrogen bonds, and then thermally reduces the ungrafted oxygen-containing functional groups under the action of glycine to prepare modified graphene modified with polysorbate-20. The modified graphene after the introduction of polysorbate-20 has excellent cycle stability. Subsequently, 3,4-ethylenedioxythiophene is in situ polymerized on the surface of the modified graphene to prepare a conductive polymer slurry. The present invention utilizes the high dielectric constant of graphene to increase the specific capacity of the capacitor and has good conductivity. During the charge and discharge cycle of the capacitor, the molecular structure of the conductive polymer will not be severely damaged, and has good cycle stability.

[0025] The present invention first presses tantalum powder into tantalum blocks, and then sintering the blocks to form a porous anode structure with a high specific surface area. Then, a low-temperature chemical formation method is used to reduce the risk of hot zone formation, so that the stress in the dielectric is released in time, and the growth of crystal nuclei in the dielectric is effectively suppressed, thereby improving the reliability of the dielectric oxide film. Then, the blocks are placed in a high-temperature steam environment for boiling and washing, which is conducive to releasing the residual stress during the formation of the dielectric oxide film. At the same time, micro defects on the surface of the dielectric oxide film can also be shielded, blocking the path of the current at the defect point, and improving the pressure resistance of the dielectric oxide film. Then, the blocks are placed in a nitrogen environment for annealing treatment, which improves the resistance temperature coefficient of the dielectric oxide film, reduces defects such as oxygen vacancies in the dielectric oxide film, reduces the resistivity, and improves the stability of the dielectric. Then, the blocks are re-chemically formed in the original energized forming liquid. The method is to allow the surface of the tantalum powder sintered body to continue to grow a tantalum pentoxide dielectric oxide film as a dielectric layer, and then before coating the conductive polymer slurry, the surface of the tantalum pentoxide dielectric layer is immersed in an aqueous solution of a silane coupling agent to reduce the surface tension of the dielectric oxide film, improve the wettability of the conductive polymer slurry on the surface of the dielectric oxide film and the permeability of the conductive polymer slurry in the porous body. After drying, the conductive polymer slurry forms a strong bond, which can inhibit the interface deformation caused by the mismatch of thermal expansion coefficients during temperature cycling and inhibit the significant change of high-temperature capacity. In addition, the silane coupling agent builds a "molecular bridge" between the conductive polymer slurry and the dielectric oxide film, thereby improving the bonding strength of the conductive polymer slurry and the dielectric interface, reducing leakage current, improving the capacitor's ability to withstand long-term high temperatures, and improving long-term reliability. Modes for Carrying Out the Invention

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] Example 1 A method for preparing a conductive polymer slurry comprises the following steps:

[0028] A. Take 0.5 g of graphene oxide and add it to 450 mL of deionized water for ultrasonic dispersion, then add 0.7 g of polysorbate-20, stir and react for 5 h, centrifuge and wash, then add the reaction product to 180 mL of deionized water, add 2.2 g of glycine, react at room temperature for 10 h, then reflux in an oil bath at 110 ° C for 24 h, wash and dry to obtain modified graphene;

[0029] B. Take 0.1 g of modified graphene and add it into 90 mL of deionized water for ultrasonic dispersion to obtain a modified graphene dispersion. Add hydrochloric acid to adjust the pH of the dispersion to 3, then add 0.1 g of 3,4-ethylenedioxythiophene monomer, and ultrasonically oscillate for 15 minutes to obtain a mixed solution. Take 0.24 g of ammonium persulfate and 0.0005 g of ferric sulfate, add them into 20 mL of deionized water to dissolve, and then add them to the mixed solution. React at room temperature for 24 hours under nitrogen protection. After the reaction, filter with 200 mesh gauze to obtain a conductive polymer slurry.

[0030] Example 2 A method for preparing a conductive polymer slurry comprises the following steps:

[0031] A. Take 0.5 g of graphene oxide and add it to 470 mL of deionized water for ultrasonic dispersion. Then add 1.1 g of polysorbate 20 and stir to react for 6 h. After centrifugation and washing, add the reaction product to 200 mL of deionized water, add 2.5 g of glycine, react at room temperature for 12 h, then reflux in an oil bath at 120 ° C for 20 h, wash and dry to obtain modified graphene;

[0032] B. Take 0.1 g of modified graphene and add it into 100 mL of deionized water for ultrasonic dispersion to obtain a modified graphene dispersion. Add hydrochloric acid to adjust the pH of the dispersion to 3, then add 0.2 g of 3,4-ethylenedioxythiophene monomer and ultrasonically oscillate for 20 min to obtain a mixed solution. Take 0.3 g of ammonium persulfate and 0.001 g of ferric sulfate and add them into 40 mL of deionized water to dissolve and then add them to the mixed solution. React at room temperature for 20 h under nitrogen protection. After the reaction is completed, filter with 200 mesh gauze to obtain a conductive polymer slurry.

[0033] Example 3 A method for preparing a conductive polymer slurry comprises the following steps:

[0034] A. Take 0.5 g of graphene oxide and add it to 500 mL of deionized water for ultrasonic dispersion, then add 1.2 g of polysorbate-20, stir and react for 6 h, centrifuge and wash, then add the reaction product to 220 mL of deionized water, add 3 g of glycine, react at room temperature for 12 h, then place it in an oil bath at 135 ° C and reflux for 24 h, wash and dry to obtain modified graphene;

[0035] B. Take 0.1 g of modified graphene and add it into 110 mL of deionized water for ultrasonic dispersion to obtain a modified graphene dispersion. Add hydrochloric acid to adjust the pH of the dispersion to 4, then add 0.3 g of 3,4-ethylenedioxythiophene monomer, and ultrasonically oscillate for 30 min to obtain a mixed solution. Take 0.5 g of ammonium persulfate and 0.0015 g of ferric sulfate, add them into 60 mL of deionized water to dissolve, and then add them to the mixed solution. React at room temperature for 24 h under nitrogen protection. After the reaction, filter with 200 mesh gauze to obtain a conductive polymer slurry.

[0036] In the following embodiments and comparative examples, taking a 50V22μF H-shell tantalum electrolytic capacitor product as an example, the method of pressing tantalum powder into tantalum blocks is as follows: tantalum powder with a specific capacity of 50000μF·V / g is selected and evenly mixed with 3% (mass percentage) of camphor (anhydrous ethanol mixed powder), and after the mixed powder is dried, the mixed powder is pressed into tantalum blocks of corresponding sizes.

[0037] Example 4 A method for preparing an organic chip-type solid tantalum electrolytic capacitor comprises the following steps:

[0038] S1, take tantalum powder and press it into tantalum blocks with tantalum wire leads. -4 The mixture was sintered at 1300°C for 25 min under a Pa vacuum condition, and then the vacuum was broken when the temperature dropped to 60°C to obtain a sintered block.

[0039] S2. Immerse the sintered block in 0.1% phosphoric acid at 5°C to form an amorphous dielectric, boil and wash in a high-temperature steam environment at 100°C, and then vacuum anneal. The vacuum annealing temperature is 250°C and the vacuum annealing time is 30 minutes. Then, immerse in 0.1% phosphoric acid at 60°C and apply a 40V DC voltage and a current density of 20mA / g to energize. The constant voltage is maintained for 2 hours, and then boil and wash with deionized water for 10 minutes to obtain a tantalum core with a dielectric oxide film formed.

[0040] S3, dipping the tantalum core into a 0.5% γ-aminopropyltriethoxysilane aqueous solution for 10 minutes, drying it in an oven, and then repeatedly dipping it into a conductive polymer slurry and drying it in an oven to obtain a cathode-coated anode tantalum core assembly structure;

[0041] S4. Coating the cathode-wrapped anode tantalum core assembly structure with a graphite layer, and then coating the outer layer with a cathode-leaded silver paste layer, and encapsulating it to prepare an organic chip-type solid tantalum electrolytic capacitor.

[0042] Example 5 A method for preparing an organic chip-type solid tantalum electrolytic capacitor comprises the following steps:

[0043] S1, take tantalum powder and press it into tantalum blocks with tantalum wire leads. -4 The sintering was carried out at 1450℃ for 30min under the vacuum condition of Pa, and then the vacuum was broken when the temperature dropped to 60℃ to obtain a sintered block;

[0044] S2. The sintered block is immersed in 0.5% phosphoric acid at 10°C to form an amorphous dielectric, and then boiled and washed in a high-temperature steam environment at 110°C and vacuum annealed at a temperature of 300°C for 45 minutes. The sintered block is then immersed in 0.5% phosphoric acid at 65°C and energized at a DC voltage of 65V and a current density of 30mA / g, and the constant voltage is maintained for 3 hours. The tantalum core with a dielectric oxide film is then boiled and washed with deionized water for 25 minutes to obtain a tantalum core;

[0045] S3, dipping the tantalum core in a 0.5% γ-aminopropyltriethoxysilane aqueous solution for 15 minutes, drying it in an oven, and then repeatedly dipping it in a conductive polymer slurry and drying it in an oven to obtain a cathode-coated anode tantalum core assembly structure;

[0046] S4. Coating the cathode-wrapped anode tantalum core assembly structure with a graphite layer, and then coating the outer layer with a cathode-leaded silver paste layer, and encapsulating it to prepare an organic chip-type solid tantalum electrolytic capacitor.

[0047] Example 6 A method for preparing an organic chip-type solid tantalum electrolytic capacitor comprises the following steps:

[0048] S1, take tantalum powder and press it into tantalum blocks with tantalum wire leads. -3 The sintering was carried out at 1550℃ for 40min under Pa vacuum conditions, and then the vacuum was broken when the temperature dropped to 80℃ to obtain a sintered block.

[0049] S2. The sintered block is immersed in 2% phosphoric acid at 15°C to form an amorphous dielectric, and then boiled in a high-temperature steam environment at 120°C and vacuum annealed at a temperature of 450°C for 60 minutes. The sintered block is then immersed in 2% phosphoric acid at 80°C and energized at a DC voltage of 75V and a current density of 60mA / g, and the constant voltage is maintained for 4 hours. The sintered block is then boiled in deionized water for 50 minutes to obtain a tantalum core with a dielectric oxide film formed thereon.

[0050] S3, dipping the tantalum core into a 1% γ-aminopropyltriethoxysilane aqueous solution for 20 minutes, drying it in an oven, and then dipping it into a conductive polymer slurry multiple times and drying it in an oven to obtain a cathode-coated anode tantalum core assembly structure;

[0051] S4. Coating the cathode-wrapped anode tantalum core assembly structure with a graphite layer, and then coating the outer layer with a cathode-leaded silver paste layer, and encapsulating it to prepare an organic chip-type solid tantalum electrolytic capacitor.

[0052] Comparative Example 1 A method for preparing a conductive polymer slurry comprises the following steps:

[0053] A. Prepare an aqueous solution of ferric p-toluenesulfonate with a mass concentration of 20%;

[0054] B. Prepare an ethanol solution b with a mass concentration of 30% 3,4-ethylenedioxythiophene;

[0055] C. The anode body of tantalum pentoxide forming the dielectric layer is placed in solution a and immersed for 5 minutes, then taken out and kept at room temperature for 120 minutes to allow the solution to fully penetrate the porous anode body. Then, the anode body is placed in solution b and immersed for 1 minute, then taken out and kept at room temperature for 90 minutes to obtain a conductive polymer slurry.

[0056] Comparative Example 2 A method for preparing an organic chip solid tantalum electrolytic capacitor comprises the following steps:

[0057] S1, take tantalum powder and press it into tantalum blocks with tantalum wire leads. -4 The mixture was sintered at 1400°C for 30 min under a Pa vacuum condition, and then the vacuum was broken when the temperature dropped to 60°C to obtain a sintered block.

[0058] S2, immersing the sintered block in 2% phosphoric acid at 80°C and applying a 50V DC voltage and a current density of 50mA / g for energization, and maintaining the constant voltage for 3 hours, followed by boiling and washing with deionized water for 40 minutes to obtain a tantalum core with a dielectric oxide film formed thereon;

[0059] S3, repeatedly immersing the tantalum core in the conductive polymer slurry for multiple times, and drying it in an oven to obtain a cathode-coated anode tantalum core assembly structure;

[0060] S4. Coating the cathode-wrapped anode tantalum core assembly structure with a graphite layer, and then coating the outer layer with a cathode-leaded silver paste layer, and encapsulating it to prepare an organic chip-type solid tantalum electrolytic capacitor.

[0061] Comparative Example 3 A method for preparing an organic chip solid tantalum electrolytic capacitor comprises the following steps:

[0062] S1, take tantalum powder and press it into tantalum blocks with tantalum wire leads. -3 The sintering was carried out at 1450℃ for 30min under the vacuum condition of Pa, and then the vacuum was broken when the temperature dropped to 60℃ to obtain a sintered block;

[0063] S2. The sintered block is immersed in 0.5% phosphoric acid at 10°C to form an amorphous dielectric, and then boiled in a high-temperature steam environment at 100°C and vacuum annealed at a temperature of 300°C for 45 minutes. The sintered block is then immersed in 0.5% phosphoric acid at 65°C and energized at a DC voltage of 70V and a current density of 50mA / g, and the voltage is maintained at a constant level for 4 hours. The sintered block is then boiled in deionized water for 60 minutes to obtain a tantalum core with a dielectric oxide film formed thereon.

[0064] S3, dipping the tantalum core in a 1% γ-aminopropyltriethoxysilane aqueous solution for 15 minutes, drying it in an oven, and then repeatedly dipping it in the conductive polymer slurry prepared in Comparative Example 1 and drying it in an oven to obtain a cathode-coated anode tantalum core assembly structure;

[0065] S4. Coating the cathode-wrapped anode tantalum core assembly structure with a graphite layer, and then coating the outer layer with a cathode-leaded silver paste layer, and encapsulating it to prepare an organic chip-type solid tantalum electrolytic capacitor.

[0066] Performance testing

[0067] The solid tantalum electrolytic capacitors prepared in Examples 4-6 and Comparative Examples 2-3 were tested for leakage current at 25°C, loss tangent at 85°C and 125°C, and capacitance change after a 2000h life test. The data results are shown in the following table:

[0068] It can be seen from the data in the above table that the solid tantalum electrolytic capacitors prepared in Examples 4-6 of the present invention have lower leakage current than that in Comparative Examples 1-2. The solid tantalum electrolytic capacitors prepared in Examples 4-6 have excellent ability to withstand high temperature shock and long-term high temperature, low capacity change rate, and significantly improved temperature stability of the capacitor.

[0069] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0070] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A method for preparing an organic chip solid tantalum electrolytic capacitor, characterized in that: The following steps are involved: S1. Take tantalum powder and press it into tantalum blocks with tantalum wire leads. -4 ~1×10 -3 Sintering at 1300-1550°C for 25-40 min under a vacuum condition of Pa, then breaking the vacuum when the temperature drops to 60-80°C to obtain a sintered block; S2, immersing the sintered block in an energy forming liquid at 5-15°C to form an amorphous dielectric, boiling and washing in a high-temperature steam environment of 100-120°C and then vacuum annealing, and then immersing it in the original energy forming liquid at 60-80°C and applying a DC voltage, and maintaining a constant voltage for 2-4 hours, and then boiling and washing with deionized water for 10-60 minutes to remove the residual energy forming liquid, to obtain a tantalum core with a dielectric oxide film; S3, dipping the tantalum core in a silane coupling agent aqueous solution for 10 to 20 minutes, drying it in an oven after dipping, and then dipping it in a conductive polymer slurry repeatedly, and drying it in an oven to obtain a cathode-coated anode tantalum core assembly structure; S4, coating the cathode-coated anode tantalum core structure with a graphite layer, and then coating the outer layer with a silver paste layer led out from the cathode, and encapsulating to prepare an organic chip-type solid tantalum electrolytic capacitor; In step S3, the silane coupling agent is γ-aminopropyltriethoxysilane, and the mass fraction of the silane coupling agent is 0.5-1%; The method for preparing the conductive polymer slurry in step S3 comprises the following steps: A. Take graphene oxide and add it to deionized water for ultrasonic dispersion, then add polysorbate-20, stir and react for 5-7 hours, centrifuge and wash, then add the reaction product to deionized water, add glycine, react at room temperature for 10-12 hours, then reflux in an oil bath at 110-135°C for 20-24 hours, wash and dry to obtain modified graphene; B. Take the modified graphene and add deionized water for ultrasonic dispersion to obtain a modified graphene dispersion, add hydrochloric acid to adjust the pH of the dispersion to 3-4, then add 3,4-ethylenedioxythiophene monomer, ultrasonically oscillate for 15-30 minutes to obtain a mixed solution, take ammonium persulfate and ferric sulfate, add them to deionized water to dissolve, and then add them to the mixed solution, react at room temperature for 20-24 hours under nitrogen protection, and filter with 200 mesh gauze after the reaction to obtain a conductive polymer slurry; In the step A, the addition ratio of graphene oxide, deionized water, polysorbate 20, deionized water and glycine is 0.5 g: 450-500 mL: 0.7-1.2 g: 180-220 mL: 2.2-3 g; In the step B, the addition ratio of modified graphene, deionized water, 3,4-ethylenedioxythiophene, ammonium persulfate, ferric sulfate and deionized water is 0.1 g: 90-110 mL: 0.1-0.3 g: 0.2-0.5 g: 0.0005-0.0015 g: 20-60 mL.

2. The method for preparing an organic chip solid tantalum electrolytic capacitor according to claim 1, characterized in that: The method for pressing tantalum powder into tantalum blocks in step S1 is specifically as follows: tantalum powder having a specific capacity corresponding to the capacitor voltage is selected and added with camphor and mixed evenly to form a mixed powder; after the mixed powder is dried, the mixed powder is pressed into tantalum blocks of corresponding sizes, wherein the camphor is a mixture of camphor powder and anhydrous ethanol.

3. The method for preparing an organic chip solid tantalum electrolytic capacitor according to claim 1, characterized in that: In the step S2, the energy forming liquid is phosphoric acid, and the mass fraction of the energy forming liquid is 0.1-2%.

4. The method for preparing an organic chip solid tantalum electrolytic capacitor according to claim 1, characterized in that: In step S2, the vacuum annealing temperature is 250° C. to 450° C., and the vacuum annealing time is 30-60 min.

5. The method for preparing an organic chip solid tantalum electrolytic capacitor according to claim 1, characterized in that: In step S2, the DC voltage is 0.6 to 1.5 times the rated DC voltage, and the current density is 20 to 60 mA / g.

6. An organic chip solid tantalum electrolytic capacitor, characterized in that: Prepared by the preparation method described in any one of claims 1 to 5.

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