Search

CN-122025425-A - Integrated into one piece does not have carbon dysmorphism foam aluminium electrolytic capacitor positive pole

CN122025425ACN 122025425 ACN122025425 ACN 122025425ACN-122025425-A

Abstract

The invention discloses an integrally formed carbon-free special-shaped foam aluminum electrolytic capacitor anode and a preparation method thereof, and belongs to the technical field of electrolytic capacitor electrode materials. According to the invention, spherical atomized pure aluminum powder is used as a matrix, a carbonless pore-forming agent and a carbonless inorganic binder are matched, a die matched with a cavity is customized according to the installation space of target equipment, and the special-shaped open-cell foam aluminum anode with a solid welding area is prepared through layering, powder spreading, cold press molding, 180-250 ℃ low-temperature curing, synchronous pore-forming, post-treatment and global anodic oxidation. The method has the advantages that no carbon source is introduced in the whole process, aluminum carbide is prevented from being generated from the source, the problems of capacitor bulge and internal resistance surge pain caused by carbon residue in the prior art are solved, aluminum powder is prevented from being excessively oxidized by low-temperature solidification, the aluminum powder is integrally formed without splicing, any special-shaped installation space can be adapted, the space utilization rate is improved by 3-10 times, the effective specific surface area of the prepared anode is 500-800 times, the aluminum foil is far superior to that of the traditional aluminum foil corrosion, and the method is perfectly adapted to the customized application requirements of liquid/solid electrolytic capacitors.

Inventors

  • Request for anonymity

Assignees

  • 广西钦州市华源电子有限公司

Dates

Publication Date
20260512
Application Date
20260328

Claims (15)

  1. 1. The integrated forming carbon-free special-shaped foam aluminum electrolytic capacitor anode is characterized by comprising an integrated forming foam aluminum matrix, wherein the foam aluminum matrix is of a special-shaped structure which is completely matched with the shape of a target equipment installation space, the foam aluminum matrix is of a carbon-free pure aluminum skeleton structure with three-dimensional communicated open pores, a solid pure aluminum welding area which is compact and nonporous is integrated in a lead welding position of the foam aluminum matrix, and all outer surfaces of the foam aluminum matrix and the wall surfaces of the three-dimensional communicated micropores are fully covered with a layer of uniform and compact structure A dielectric film.
  2. 2. The integrally formed carbon-free profiled aluminum foam electrolytic capacitor anode of claim 1, wherein the aluminum foam substrate has a porosity of 40% -80%, an average pore size of 1-50 μm, and a volume resistivity 。
  3. 3. The integrally formed carbon-free profiled aluminum foam electrolytic capacitor anode of claim 1, wherein the The thickness uniformity deviation of the dielectric film is less than or equal to 5 percent, and the foamed aluminum matrix has no aluminum carbide residue.
  4. 4. The integrated carbon-free special-shaped foam aluminum electrolytic capacitor anode according to claim 1, wherein the thickness of the solid pure aluminum welding area is 0.2-0.5mm, and the solid pure aluminum welding area is fixedly connected with a positive electrode lead through ultrasonic aluminum spot welding or laser fusion welding.
  5. 5. The integrally formed carbon-free special-shaped foam aluminum electrolytic capacitor anode as claimed in claim 1, wherein the foam aluminum substrate is of a hollow cylindrical structure, and the foam aluminum substrate is of a hollow cylindrical structure The dielectric film is covered on the surfaces of the inner wall, the outer wall and the micropore wall of the hollow cylinder.
  6. 6. The integrated into one piece does not have carbon dysmorphism foam aluminum electrolytic capacitor positive pole of claim 1, wherein, foam aluminum base member is any special-shaped structure in U type, L type, arc, ultra-thin flat type, and the reservation installation space of on-vehicle OBC, folding electronic equipment, unmanned aerial vehicle, industrial control equipment is adapted.
  7. 7. The integrally formed carbon-free special-shaped foam aluminum electrolytic capacitor anode according to claim 1, wherein all structural corners of the foam aluminum substrate are provided with rounded corner transitions of 0.5mm or more.
  8. 8. A method for preparing an integrally formed carbon-free profiled aluminum foam electrolytic capacitor anode as claimed in any one of claims 1 to 7, comprising the steps of: S1, customizing a cavity, namely designing and processing a mold cavity which is completely matched with the shape of the installation space according to the reserved installation space of target equipment, and performing carbon-free anti-sticking coating treatment on the inner wall of the mold; S2, proportioning, namely weighing 100 parts of spherical atomized pure aluminum powder, 5-40 parts of carbon-free pore-forming agent, 2-15 parts of carbon-free inorganic binder and 0-5 parts of deionized water according to parts by weight, and uniformly mixing under inert atmosphere to obtain pore-forming mixed slurry; s3, layering and powder paving for molding, namely paving pure aluminum mixed slurry into a lead welding position of a die cavity to form a solid welding area preformed layer, filling the pore-forming mixed slurry into the residual space of the die cavity, and carrying out cold pressing and pressure maintaining for 20-60S at room temperature under 5-20MPa to obtain a special-shaped blank body with a solid welding area integrally; S4, low-temperature curing and pore-forming, namely placing the special-shaped blank body and the die in an inert atmosphere or a vacuum environment, raising the temperature to 180-250 ℃ at a heating rate of 1-5 ℃ per minute, and preserving the temperature for 1-4 hours to finish inorganic bonding curing and pore-forming agent removal to obtain a special-shaped foamed aluminum precursor; s5, post-treatment, namely demoulding the special-shaped foamed aluminum precursor, carrying out multistage cleaning and vacuum drying at 120-150 ℃ to remove loose oxide films and residual impurities on the surface; S6, global anodic oxidation, namely placing the dried precursor into a formation liquid, carrying out vacuum infiltration, low-pressure pre-formation and step-by-step pressure boosting formation, and carrying out in-situ growth on all outer surfaces and pore wall surfaces of the precursor uniformly and compactly And (3) a dielectric film to prepare the integrally formed carbon-free special-shaped foam aluminum electrolytic capacitor anode.
  9. 9. The method according to claim 8, wherein in step S1, the mold is made of 304/316 stainless steel, the carbon-free anti-sticking coating is a boron nitride ceramic coating, and all corners of the mold cavity are provided with rounded transitions of 0.5mm or more.
  10. 10. The preparation method of claim 8, wherein in the step S2, the particle size of the spherical atomized pure aluminum powder is 1-50 μm, the purity is more than or equal to 99.9%, the particle size of the carbon-free pore-forming agent is 1-60 μm, and the particle size of the pore-forming agent is positively correlated with the pore size of the target foamed aluminum.
  11. 11. The method according to claim 8, wherein in step S2, the carbon-free inorganic binder is aluminum phosphate sol, the solid content is 10% -30%, and the pH is 2-4.
  12. 12. The preparation method of claim 8, wherein in the step S4, the inert atmosphere is argon or nitrogen with the purity of more than or equal to 99.999%, positive pressure in the furnace is maintained in the whole process, when the carbon-free pore-forming agent is ammonium bicarbonate, the pore-forming and the curing are synchronously completed, and the ammonium bicarbonate is completely pyrolyzed into ammonia, carbon dioxide and steam in the heat preservation process and is discharged along with the atmosphere.
  13. 13. The preparation method of claim 8, wherein in step S5, the multistage cleaning is sequentially dilute nitric acid light etching cleaning with the mass fraction of 0.5% -2% for 10-30S, deionized water ultrasonic cleaning and absolute ethyl alcohol dehydration cleaning.
  14. 14. The preparation method of the porous ceramic material according to claim 8, wherein in the step S6, the vacuum degree of vacuum infiltration is less than or equal to 10Pa, the infiltration time is more than or equal to 30min, the final voltage of the gradual pressure boosting formation is higher than 10% of the rated withstand voltage of a target capacitor, the full-process temperature of formation is controlled at 30-40 ℃, and the uniformity deviation of the thickness of the oxide film of the pore wall after film formation is less than or equal to 5%.
  15. 15. An electrolytic capacitor is characterized by comprising the integrated carbon-free special-shaped foam aluminum electrolytic capacitor anode, an insulating isolation layer, electrolyte, a cathode current collector and a shell which is adaptive to the shape of the anode, wherein the insulating isolation layer is completely coated on the outer surface of the anode, the insulating isolation layer and the cathode current collector are sequentially stacked in the shell from inside to outside, and the electrolyte is completely infiltrated in three-dimensional communicated micropores of the anode and the insulating isolation layer.

Description

Integrated into one piece does not have carbon dysmorphism foam aluminium electrolytic capacitor positive pole Technical Field The invention belongs to the technical field of preparation of electrode materials of electrolytic capacitors, and particularly relates to an integrally formed carbon-free special-shaped foam aluminum electrolytic capacitor anode and a preparation method thereof. Background The aluminum electrolytic capacitor is a passive component which is most widely applied in an electronic circuit, is widely applied to the fields of consumer electronics, new energy automobiles, industrial control equipment, aerospace and the like, and the core performance of the aluminum electrolytic capacitor is determined by the specific surface area of an anode substrate, the quality of an anodic oxide film and the structural suitability. The anodes of the current commercial aluminum electrolytic capacitors all adopt electrochemical corrosion aluminum foils, two-dimensional tunnel holes are formed on the surfaces of the aluminum foils through strong acid etching, the effective specific surface area of the aluminum foils is only 80-120 times as high as that of the aluminum foils, the aluminum foils are close to physical ceilings, the development requirements of high capacity, miniaturization and customization of the capacitors cannot be met, meanwhile, the strong acid etching process has the problems of heavy pollution, high energy consumption and low yield, and the environment-friendly pressure is increasingly increased. The foamed aluminum as a three-dimensional porous structure material has extremely high theoretical specific surface area, and can perfectly replace corrosion aluminum foil as a capacitor anode matrix. The prior foam aluminum preparation technology is mainly divided into two types, namely a melt foaming method, wherein aluminum is heated to a molten state of more than 660 ℃, a foaming agent is added for stirring and foaming, and then cooling and molding are carried out, the foam aluminum prepared by the method is mainly of a closed pore structure, the pore diameter is uncontrollable, global uniform anodic oxidation cannot be realized, aluminum is extremely easy to oxidize in a high-temperature melting process, the internal resistance is increased, and the powder metallurgy sintering method comprises the steps of mixing aluminum powder with a pore-forming agent and a binder, then compacting and molding, and sintering at a high temperature of more than 450 ℃, wherein three fatal defects exist in the method: 1. in the prior art, organic resin and carbon powder are mostly adopted as binder or pore-forming agent, carbon residue is inevitably existed, and carbon reacts with aluminum at high temperature to generate aluminum carbide ),The trace water in the electrolyte can be hydrolyzed to generate methane gas and aluminum hydroxide precipitate, so that the capacitor bulges, leaks liquid, and has surge internal resistance and short service life, which is an absolute tabu of the capacitor anode; In the high-temperature sintering process of more than 2.450 ℃, an excessively thick natural oxide film is formed on the surface of aluminum powder, so that the internal resistance of an anode is increased, meanwhile, the active surface of the aluminum powder is coated by a sintering neck, the oxide film is unevenly grown in the anodic oxidation process, a complete dielectric film cannot be formed at the deep hole position, and breakdown is easy to occur; 3. The conventional aluminum foam can only prepare standard shapes such as a cylinder, a square plate and the like, cannot adapt to irregular special-shaped reserved installation space in electronic equipment, more than 70% of corner space in the equipment cannot be utilized, the power density is limited, and if special-shaped capacitors are to be prepared, standard corrosion aluminum foils are required to be punched, bent, spliced and multi-point welded for many times, the more complicated the special-shaped capacitors are, the more the procedures are, the lower the yield is, the greater the contact internal resistance at the spliced position is, and the more the pressure resistance and service life performance are attenuated. In summary, the prior art does not have an integrated foam aluminum method which is special for capacitor anodes, has no carbon residue, is prepared at low temperature, can uniformly anodize all over, can adapt to special-shaped installation space of equipment by 100%, and cannot solve the problem that carbon residue is generated in the prior artThe core pain point has the advantages of high-temperature oxidation internal resistance, uneven oxide film growth, high special-shaped customization cost and low space utilization rate. Disclosure of Invention Object of the Invention Aiming at the defects in the prior art, the invention aims to provide a method for integrally forming and preparing a carbon-free special-shaped foam aluminum cap