A high specific capacity porous electrode foil and a method of manufacturing the same

Abstract

This invention discloses a high-specific-capacity porous electrode foil and its preparation method. The porous electrode foil includes an aluminum foil substrate and a composite oxide film formed on at least one side of the aluminum foil substrate. The raw materials of the composite oxide film include aluminum powder, aluminum-silicon alloy powder, and valve metal oxide powder with a dielectric constant greater than 6.5. Since the eutectic temperature of aluminum-silicon alloy is about 577°C, when the heat treatment exceeds this temperature, the aluminum-silicon alloy begins to transform into a molten state, thereby promoting the fusion of valve metal oxide powder, aluminum powder, and the surface of the aluminum foil substrate. This ensures that the valve metal oxide powder and aluminum powder can be firmly dissolved on the aluminum foil substrate, making the structure of the porous electrode foil more stable and efficient. After the sintered aluminum foil is anodized, the valve metal oxide powder will be doped into the aluminum oxide film layer generated by anodizing, which significantly increases the ε / K value of the formed composite oxide film, ultimately achieving the purpose of improving the specific capacity of the porous electrode foil.

Description

Technical Field

[0001] This invention belongs to the field of anode foil formation technology, specifically relating to a high specific volume porous electrode foil and its preparation method. Background Technology

[0002] Electrode foil is a key raw material for aluminum electrolytic capacitors, which are one of the three essential components in various electrical appliances, computers, communication equipment, and automation equipment. The quality of the electrode foil directly affects the lifespan of the capacitor, which in turn determines the lifespan of the entire electronic device. The current trend in the electronics industry is towards miniaturization, and since capacitors occupy a significant portion of the space in electronic products, reducing the size of aluminum electrolytic capacitors is crucial for overall miniaturization. This places higher demands on the specific capacitance of the electrode foil.

[0003] According to the capacitance formula (In the formula, C is the capacitance, ε0 is the vacuum permittivity, ε is the relative permittivity of the dielectric layer, S is the surface area of ​​the dielectric layer, and d is the thickness of the dielectric layer (d = E) a *K), E a (where S is the oxide film formation voltage and K is the oxide film formation constant) It can be seen that there are two ways to increase the specific capacitance of the anode foil: one is to increase the specific surface area S of the foil, and the other is to increase the relative permittivity ε of the dielectric layer and decrease the value of K.

[0004] For example, Chinese invention patent CN 102714098B discloses an electrode material for aluminum electrolytic capacitors and its preparation method. The preparation method of the electrode material includes: (1) stacking two or more film layers composed of a composition containing at least one powder of aluminum and aluminum alloy on a substrate, wherein the average particle size D of the powder contained in each film is... 50 The average particle size D of the powder contained in two adjacent membrane layers is 1–10 μm. 50 (1) The difference is greater than 0.5 μm; (2) The two or more layers of film are sintered at a temperature of 560℃~660℃. However, the electrode material obtained by the above preparation method is only suitable for medium and low voltage formation voltage. When the formation voltage exceeds 300V, the electrode foil will be very brittle and cannot be used for the winding process of aluminum electrolytic capacitors.

[0005] For example, Chinese invention patent CN109036852B discloses a three-dimensional porous aluminum electrode foil and its preparation method. The preparation method of the electrode foil includes: (1) mixing aluminum powder, aluminum fiber and high dielectric oxide powder evenly to form a mixed powder; (2) dispersing the mixed powder evenly on both sides of the aluminum foil substrate and compacting it to form a densely packed porous foil sheet; (3) subjecting the densely packed porous foil sheet to thermal treatment and controlling the porosity to 35%-45% and the thickness to 80μm-200μm through extrusion treatment, finally forming a composite mesh porous aluminum electrode foil; (4) subjecting the thermally treated porous aluminum electrode foil to formation and energy-enhancing treatment.

[0006] Although the porous aluminum electrode foil obtained by the above preparation process has improved the applicable formation voltage, its application in the field of high-voltage formation is still limited because the thermal treatment effect is not ideal, making it difficult for the high dielectric constant valve metal oxide to form a stable molten structure with aluminum powder and aluminum substrate. Summary of the Invention

[0007] The purpose of this invention is to provide a high specific capacity porous electrode foil and its preparation method. The porous electrode foil prepared by this method can form a very stable molten structure between the composite oxide film and the aluminum foil substrate, thus expanding the application of porous electrode foil in the field of high-voltage formation.

[0008] To achieve the above-mentioned objectives, the technical solution of this invention is as follows:

[0009] A high specific capacity porous electrode foil includes an aluminum foil substrate and a composite oxide film formed on at least one side of the aluminum foil substrate. The raw materials of the composite oxide film include: aluminum powder, aluminum-silicon alloy powder and valve metal oxide powder.

[0010] The dielectric constant of the valve metal oxide is greater than 6.5.

[0011] In the composite oxide film of this invention, not only are valve metal oxide powders with a dielectric constant greater than 6.5 added, but also aluminum-silicon alloy powders are added. This not only greatly increases the specific surface area of ​​the porous electrode foil, but also the eutectic temperature of the aluminum-silicon alloy is about 577°C. When the heat treatment exceeds this temperature point, the aluminum-silicon alloy begins to transform into a molten state, thereby promoting the fusion of the valve metal oxide powder, aluminum powder and aluminum foil substrate surface. This ensures that the valve metal oxide powder and aluminum powder can be firmly dissolved on the aluminum foil substrate, making the structure of the porous electrode foil more stable and efficient.

[0012] The presence of aluminum-silicon alloy promotes the fusion of valve metal oxide powder, aluminum powder and aluminum foil substrate surface, thus reducing the thermal temperature and avoiding the shrinkage of pores between aluminum powders caused by excessively high temperatures, ensuring that the foil has a higher porosity. When the sintered aluminum foil is anodized, the valve metal oxide powder will be doped into the aluminum oxide film layer generated by anodizing, which will significantly increase the ε / K value of the composite oxide film, ultimately achieving the purpose of improving the specific capacitance of the porous electrode foil.

[0013] In the above-mentioned high specific capacity porous electrode foil, the mass ratio of valve metal oxide powder to aluminum powder is 1:(5-200);

[0014] The mass ratio of the aluminum-silicon alloy powder to aluminum powder is 1:(10-100).

[0015] Preferably, the mass ratio of the valve metal oxide powder to the aluminum powder is 1:(10-50); the mass ratio of the aluminum-silicon alloy powder to the aluminum powder is 1:(20-50).

[0016] In the above-mentioned high specific capacity porous electrode foil, the average particle size of the aluminum powder is 0.5-50 μm, and the average particle size ratio of the valve metal oxide powder to the aluminum powder is 1:(20-200).

[0017] The average particle size of the aluminum-silicon alloy powder is 0.1-10 μm.

[0018] Preferably, the aluminum powder has an average particle size of 1-10 μm, the valve metal oxide powder has an average particle size of 0.1-10 μm, and the average particle size ratio of the valve metal oxide powder to the aluminum powder is 1:(10-50).

[0019] The average particle size of the aluminum-silicon alloy powder is 0.1-3 μm.

[0020] The aluminum-silicon alloy powder used in this invention can be spherical, disc-shaped, strip-shaped, rod-shaped, or other irregular shapes, and the valve metal oxide powder can be spherical, disc-shaped, strip-shaped, rod-shaped, or other irregular shapes.

[0021] In the aforementioned high specific capacity porous electrode foil, the valve metal oxide powder is at least one of aluminum oxide, silicon dioxide, barium titanate, calcium titanate, and barium strontium titanate.

[0022] In the aforementioned high specific capacity porous electrode foil, the silicon content in the aluminum-silicon alloy powder is 10 wt.% to 13 wt.%.

[0023] In the above-mentioned high specific volume porous electrode foil, the aluminum powder is aluminum powder with a purity greater than 99.5 wt.%.

[0024] Alternatively, the aluminum powder may be an aluminum alloy powder formed by aluminum and at least one of silicon, iron, copper, manganese, magnesium, chromium, zinc, titanium, vanadium, gallium, nickel, boron and zirconium, wherein the content of the other metals besides aluminum in the aluminum alloy powder is less than 100 ppm.

[0025] In the above-mentioned high specific capacity porous electrode foil, the raw materials of the composite oxide film also include binders and solvents;

[0026] The flash point of the adhesive is below 650°C.

[0027] When aluminum powder, aluminum-silicon alloy powder, valve metal oxide powder, binder and solvent are mixed, they can be coated on the surface of aluminum foil substrate in fluid form without generating dust. Furthermore, due to the presence of the binder, after the mixed fluid is dried, the binder can also bind the aluminum powder and valve metal oxide powder, and no dust will be generated during rolling, ensuring a good working environment in the workshop and effectively eliminating the hidden dangers of dust explosion.

[0028] The flash point of the binder used in this invention is below 650°C, which is the sintering temperature of the composite oxide film. This ensures that the binder is completely burned and removed during sintering, and the resulting composite oxide film contains only aluminum, aluminum-silicon alloy and valve metal oxides, which will not affect the performance of the composite oxide film.

[0029] Preferably, in the above-mentioned high specific capacity porous electrode foil, the binder is at least one of polyvinylidene fluoride, methylcellulose, ethylcellulose, triphenylmethylcellulose, cyanoethylcellulose, carboxymethylcellulose, carboxyethylcellulose, aminoethylcellulose, or ethoxycellulose.

[0030] The solvent is water or an organic solvent.

[0031] This invention does not have many requirements regarding the type of solvent, as long as it can ensure that the aluminum powder, valve metal oxide and binder can be mixed into a fluid, and that the performance of the aluminum powder, valve metal oxide and binder is not affected, and that it is easy to volatilize during the subsequent drying process.

[0032] This invention does not have special requirements for the amount of binder and solvent. As long as the mass fraction of binder in the mixed fluid is controlled at 1-7 wt.%, and the amount of solvent is controlled to ensure that the solid content of the mixed fluid is greater than 50%.

[0033] The present invention also provides two methods for preparing the above-mentioned high specific capacity porous electrode foil.

[0034] The first preparation method includes the following steps:

[0035] (1) Mix aluminum powder, valve metal oxide powder and aluminum-silicon alloy powder according to a preset mass ratio to obtain a mixed powder;

[0036] (2) The mixed powder is dispersed on at least one side of the aluminum foil substrate and then compacted to obtain a composite aluminum foil;

[0037] When the mixed powder is dispersed on the surface of the aluminum foil substrate, the surface roughness of the aluminum foil substrate should be controlled to not exceed ±8μm; then, a cold press roller is used to compact the mixed powder onto the surface of the aluminum foil substrate, with the roller pressure controlled at 50-300kg.

[0038] (3) The composite aluminum foil is placed in an inert gas protective atmosphere and heat-treated at 550-660℃ for 1-60 minutes;

[0039] The inert gas protective atmosphere is nitrogen or argon.

[0040] (4) Cool the heat-treated composite aluminum foil to 300°C and roll it to control the thickness and porosity of the sintered aluminum foil to obtain sintered aluminum foil;

[0041] The rolling pressure is preferably controlled at 10-20 kg to control the thickness of the obtained sintered aluminum foil at 130 μm and the porosity at 40-50%.

[0042] (5) The sintered aluminum foil is subjected to an energizing-anodic oxidation treatment to obtain the high specific volume porous electrode foil;

[0043] The empowerment-anodic oxidation treatment preferably employs an inorganic acidification process or an organic acidification process.

[0044] The second preparation method includes the following steps:

[0045] (1) Aluminum powder, valve metal oxide powder, aluminum-silicon alloy powder, binder and solvent are mixed according to a preset mass ratio to obtain a mixed fluid;

[0046] (2) The mixed fluid is coated on at least one side of the aluminum foil substrate, dried and compacted to obtain a composite aluminum foil;

[0047] The method of applying the mixed fluid to the aluminum foil substrate can be scraping, spraying, dipping, transfer coating, screen printing, etc.; the coating thickness is preferably 1-500μm, more preferably 30-200μm;

[0048] After drying, the solvent evaporates, while the binder binds the aluminum powder, valve metal oxide powder and aluminum-silicon alloy powder to the surface of the aluminum foil substrate. Pressing can be done using a cold press roller.

[0049] (3) The composite aluminum foil is placed at 200-500℃ for adhesive removal heat treatment to remove the adhesive. The adhesive removal heat treatment time is 0-8h.

[0050] The temperature used during the heat treatment of adhesive removal should be equivalent to (or higher than) the flash point of the adhesive used to ensure that there is no adhesive residue after the heat treatment of adhesive removal.

[0051] (4) The composite aluminum foil that has undergone debinding heat treatment is placed at 450-660℃ for sintering heat treatment for 1-24 hours to obtain sintered aluminum foil.

[0052] The preferred temperature for the sintering heat treatment is 550-650℃; the sintering heat treatment can be carried out under vacuum, inert atmosphere, oxidizing atmosphere (in air) or reducing atmosphere.

[0053] (5) The sintered aluminum foil is subjected to an energizing-anodic oxidation treatment to obtain the high specific volume porous electrode foil;

[0054] The empowerment-anodic oxidation treatment preferably employs an inorganic acidification process or an organic acidification process.

[0055] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0056] (1) In the porous electrode foil of the present invention, not only valve metal oxide powder with a dielectric constant greater than 6.5 is added to the composite oxide film, but also aluminum-silicon alloy powder is added. This not only greatly increases the specific surface area of ​​the porous electrode foil, but also the eutectic temperature of the aluminum-silicon alloy is about 577°C. When the heat treatment exceeds this temperature point, the aluminum-silicon alloy begins to transform into a molten state, thereby promoting the fusion of valve metal oxide powder, aluminum powder and aluminum foil substrate surface, ensuring that valve metal oxide powder and aluminum powder can be firmly dissolved on aluminum foil substrate, making the structure of the porous electrode foil more stable and efficient.

[0057] (2) In this invention, the presence of aluminum-silicon alloy promotes the fusion of valve metal oxide powder, aluminum powder and aluminum foil substrate surface, thus reducing the thermalization temperature and avoiding the shrinkage of pores between aluminum powders caused by excessively high temperature, ensuring that the foil has a higher porosity. When the sintered aluminum foil is anodized, the valve metal oxide powder will be doped into the aluminum oxide film layer generated by anodization, which significantly increases the ε / K value of the composite oxide film, ultimately achieving the purpose of improving the specific volume of the porous electrode foil. Compared with the electrode foil prepared without adding valve metal oxide powder or aluminum-silicon alloy powder, the specific volume of the porous electrode foil of this invention can be increased by 5-20%, and the energy consumption of the formation process can be reduced by 5-10%.

[0058] (3) In this invention, the raw materials of the composite oxide film also include binder and solvent. When aluminum powder, aluminum-silicon alloy powder, valve metal oxide powder, binder and solvent are mixed, they can be coated on the surface of aluminum foil substrate in fluid form without dust generation. In addition, due to the presence of binder, when the mixed fluid is dried, the binder can also bind the aluminum powder and valve metal oxide powder, and no dust generation will occur during rolling, ensuring a good working environment in the workshop and effectively eliminating the hidden dangers of dust explosion. Furthermore, since the flash point of the binder used in this invention is below 650°C, and 650°C is the sintering temperature of the composite oxide film, it can be ensured that the binder is completely burned and removed during sintering. The obtained composite oxide film contains only aluminum, aluminum-silicon alloy and valve metal oxide, which will not affect the performance of the composite oxide film. Attached Figure Description

[0059] Figure 1 This is an electron microscope image (2000x) of the high specific volume porous electrode foil of the present invention. Detailed Implementation

[0060] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] Example 1

[0062] This embodiment describes a method for preparing a high-specific-capacity porous electrode foil, comprising the following steps:

[0063] (1) Aluminum powder, valve metal oxide powder, aluminum-silicon alloy powder, binder and solvent are mixed according to a preset mass ratio to obtain a mixed fluid;

[0064] Specifically, aluminum powder with an average particle size of 3 μm, titanium dioxide powder with an average particle size of 100 nm, aluminum-silicon alloy powder with an average particle size of 500 nm (silicon content of 11.7 wt.%), polyvinylidene fluoride, and N-methylpyrrolidone are mixed to obtain a mixed fluid.

[0065] The mass ratio of titanium dioxide powder to aluminum powder is 1:20; the mass ratio of aluminum-silicon alloy powder to aluminum powder is 1:100; the mass ratio of polyvinylidene fluoride to aluminum powder is 1:100; and the solid content of the mixed fluid is 60%.

[0066] (2) The mixed fluid is coated on at least one side of the aluminum foil substrate, dried and compacted to obtain a composite aluminum foil;

[0067] Specifically, the mixed fluid is symmetrically coated on both sides of an aluminum foil substrate with a thickness of 20μm using a doctor blade coater, with a single-sided coating thickness of 55-65μm, so that the total thickness of the composite aluminum foil after drying and compaction reaches 130μm.

[0068] (3) The composite aluminum foil was subjected to a heat treatment at 450°C to remove the adhesive. The heat treatment time was 2 hours.

[0069] (4) The composite aluminum foil that has undergone debinding heat treatment is placed in an argon protective atmosphere and sintered at 620°C for 5 hours to obtain sintered aluminum foil.

[0070] (5) The sintered aluminum foil is subjected to an energizing-anodic oxidation treatment using an inorganic acidification process to obtain the high specific capacity porous electrode foil of this embodiment.

[0071] Examples 2-4

[0072] The preparation methods of high specific capacity porous electrode foils in Examples 2-4 are basically the same as those in Example 1, except that in step (1), the mass ratio of aluminum silicon alloy powder to aluminum powder is adjusted to 1:50, 1:20, and 1:10.

[0073] Comparative Example 1

[0074] A 130μm thick soft optical foil that has undergone annealing is used to form tunnel holes using a known etching process, and then the foil is processed by chemical formation to obtain an anode foil.

[0075] Comparative Example 2

[0076] This comparative example describes a process for preparing a porous electrode foil, including:

[0077] (1) Mix aluminum powder and valve metal oxide powder according to a preset mass ratio to obtain a mixed powder;

[0078] Specifically, aluminum powder with an average particle size of 3 μm and titanium dioxide powder with an average particle size of 100 nm are mixed evenly at a mass ratio of 1:20 to obtain a mixed powder.

[0079] (2) Disperse the mixed powder on one side of the aluminum foil substrate and compact it to obtain composite aluminum foil;

[0080] Specifically, the mixed powder is pushed onto a 20μm aluminum foil substrate, the uniformity of the single-sided surface is controlled by a scraper, and the powder layer is pressed to a thickness of 65μm by a cold roller;

[0081] (3) The composite aluminum foil was placed under the support of a ceramic roller and heat-treated at 610°C for 5 minutes in an argon protective atmosphere;

[0082] (4) Cool the heat-treated composite aluminum foil to 300°C and roll it to obtain sintered aluminum foil;

[0083] The roller pressure is 10 kg, and the porosity is controlled at 40-50%.

[0084] (5) Repeat steps (2)-(4) to composite a mixed powder layer on the other side of the aluminum foil to obtain a sintered aluminum foil with a total thickness of 130μm;

[0085] (6) The sintered aluminum foil was subjected to an energizing-anodic oxidation process using an inorganic acidification process to obtain the high specific capacity porous electrode foil of this comparative example.

[0086] Comparative Example 3

[0087] The preparation process of Comparative Example 3 is basically the same as that of Example 1, except that it does not contain aluminum-silicon alloy powder.

[0088] The porous electrode foils prepared in Examples 1-4 and Comparative Examples 1-3 were tested according to the SJ / T 11140-1997 standard. The test results are shown in Table 1.

[0089] Table 1

[0090]

[0091] Note: ※ The specific volume improvement rate and energy consumption reduction rate are obtained by comparing with Comparative Example 1, and the same applies below.

[0092] Examples 5-8

[0093] The preparation process of the porous electrode foil in Examples 5-8 is basically the same as that in Example 3, except that:

[0094] The average particle size of the aluminum-silicon alloy powder was adjusted to 0.1μm, 0.3μm, 1.0μm, and 3.0μm, respectively.

[0095] The porous electrode foils prepared in Examples 5-8 were tested according to the SJ / T 11140-1997 standard. The test results are shown in Table 2.

[0096] Table 2

[0097]

[0098] Examples 9-10

[0099] The preparation process of the porous electrode foil in Examples 9-10 is basically the same as that in Example 7, except that the valve metal oxide is changed to calcium titanate and barium titanate respectively.

[0100] Electron micrograph of the porous electrode foil prepared in Example 10 is shown below. Figure 1 .

[0101] The porous electrode foils prepared in Examples 9-10 were tested according to the SJ / T 11140-1997 standard. The test results are shown in Table 3.

[0102] Table 3

[0103]

[0104] Examples 11-13

[0105] The preparation process of the porous electrode foil in Examples 11-13 is basically the same as that in Example 10, except that the mass ratio of barium titanate powder to aluminum powder is 1:80, 1:40, and 1:10, respectively.

[0106] The porous electrode foils prepared in Examples 11-13 were tested according to the SJ / T 11140-1997 standard. The test results are shown in Table 4.

[0107] Table 4

[0108]

Claims

1. A method for preparing a high specific capacity porous electrode foil, characterized in that, The high specific capacity porous electrode foil includes an aluminum foil substrate and a composite oxide film formed on at least one side of the aluminum foil substrate. The raw materials of the composite oxide film include: aluminum powder, aluminum-silicon alloy powder and valve metal oxide powder. The dielectric constant of the valve metal oxide is greater than 6.5; The preparation method includes the following steps: (1) Mix aluminum powder, valve metal oxide powder and aluminum-silicon alloy powder according to the preset mass ratio to obtain a mixed powder; (2) The mixed powder is dispersed on at least one side of the aluminum foil substrate and then compacted to obtain a composite aluminum foil; (3) The composite aluminum foil is placed in an inert gas protective atmosphere and heat-treated at 550-660℃ for 1-60 min; (4) Cool the heat-treated composite aluminum foil to 300°C and roll it to control the thickness and porosity of the sintered aluminum foil to obtain sintered aluminum foil; (5) The sintered aluminum foil is subjected to an energizing-anodic oxidation treatment to obtain the high specific capacity porous electrode foil.

2. The method for preparing the high specific capacity porous electrode foil as described in claim 1, characterized in that, The mass ratio of the valve metal oxide powder to aluminum powder is 1:(5-200). The mass ratio of the aluminum-silicon alloy powder to aluminum powder is 1:(10-100).

3. The method for preparing high specific capacity porous electrode foil as described in claim 1, characterized in that, The aluminum powder has an average particle size of 0.5-50 μm, and the average particle size ratio of the valve metal oxide powder to the aluminum powder is 1:(20-200). The average particle size of the aluminum-silicon alloy powder is 0.1-10 μm.

4. The method for preparing high specific capacity porous electrode foil as described in claim 1, characterized in that, The valve metal oxide powder is at least one of aluminum oxide, silicon dioxide, barium titanate, calcium titanate, and barium strontium titanate.

5. The method for preparing high specific capacity porous electrode foil as described in claim 1, characterized in that, The silicon content in the aluminum-silicon alloy powder is 10 wt.% to 13 wt.%.

6. The method for preparing high specific capacity porous electrode foil as described in claim 1, characterized in that, The aluminum powder mentioned is aluminum powder with a purity greater than 99.5 wt.%. Alternatively, the aluminum powder may be an aluminum alloy powder formed by aluminum and at least one of silicon, iron, copper, manganese, magnesium, chromium, zinc, titanium, vanadium, gallium, nickel, boron and zirconium, wherein the content of the other metals besides aluminum in the aluminum alloy powder is less than 100 ppm.

7. A method for preparing a high specific capacity porous electrode foil, characterized in that, The high specific capacity porous electrode foil includes an aluminum foil substrate and a composite oxide film formed on at least one side of the aluminum foil substrate. The raw materials of the composite oxide film include: aluminum powder, aluminum-silicon alloy powder, valve metal oxide powder, binder and solvent. The dielectric constant of the valve metal oxide is greater than 6.5; The flash point of the adhesive is below 650°C; The preparation method includes the following steps: (1) Aluminum powder, valve metal oxide powder, aluminum-silicon alloy powder, binder and solvent are mixed according to a preset mass ratio to obtain a mixed fluid; (2) The mixed fluid is coated on at least one side of the aluminum foil substrate, dried and compacted to obtain a composite aluminum foil; (3) The composite aluminum foil is placed at 200-500℃ for debonding heat treatment to remove the adhesive. The debonding heat treatment time is 0-8 h. (4) The composite aluminum foil that has undergone debinding heat treatment is placed at 450-660℃ for sintering heat treatment for 1-24 h to obtain sintered aluminum foil; (5) The sintered aluminum foil is subjected to an energizing-anodic oxidation treatment to obtain the high specific capacity porous electrode foil.

8. The method for preparing high specific capacity porous electrode foil as described in claim 7, characterized in that, The mass ratio of the valve metal oxide powder to aluminum powder is 1:(5-200). The mass ratio of the aluminum-silicon alloy powder to aluminum powder is 1:(10-100).

9. The method for preparing a high specific capacity porous electrode foil as described in claim 7, characterized in that, The aluminum powder has an average particle size of 0.5-50 μm, and the average particle size ratio of the valve metal oxide powder to the aluminum powder is 1:(20-200). The average particle size of the aluminum-silicon alloy powder is 0.1-10 μm.

10. The method for preparing a high specific capacity porous electrode foil as described in claim 7, characterized in that, The valve metal oxide powder is at least one of aluminum oxide, silicon dioxide, barium titanate, calcium titanate, and barium strontium titanate.

11. The method for preparing a high specific capacity porous electrode foil as described in claim 7, characterized in that, The silicon content in the aluminum-silicon alloy powder is 10 wt.% to 13 wt.%.

12. The method for preparing high specific capacity porous electrode foil as described in claim 7, characterized in that, The aluminum powder mentioned is aluminum powder with a purity greater than 99.5 wt.%. Alternatively, the aluminum powder may be an aluminum alloy powder formed by aluminum and at least one of silicon, iron, copper, manganese, magnesium, chromium, zinc, titanium, vanadium, gallium, nickel, boron and zirconium, wherein the content of the other metals besides aluminum in the aluminum alloy powder is less than 100 ppm.

13. The method for preparing a high specific capacity porous electrode foil as described in claim 7, characterized in that, The adhesive is at least one of polyvinylidene fluoride, methylcellulose, ethylcellulose, triphenylmethylcellulose, cyanoethylcellulose, carboxymethylcellulose, carboxyethylcellulose, aminoethylcellulose, or ethoxycellulose; The solvent is water or an organic solvent.

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