A method for preparing anode material with high porosity

Abstract

The present invention belongs to the technical field of capacitors, and in particular to a method for preparing a high-porosity anode material. The present invention aims at the problem that the porosity of anode materials in the prior art still needs to be improved, and provides a method for preparing a high-porosity anode material, including step one: mixing aluminum powder, valve metal oxide powder, binder and solvent, stirring for 5-20h, and obtaining aluminum powder slurry; step two: pouring the aluminum powder slurry obtained in step one into a mold, applying a pressing force to the aluminum powder slurry using a pressing plate, and drying after pressing to obtain an aluminum foil; step three: sintering the aluminum foil obtained in step two under a protective gas environment to obtain a high-porosity anode material. The present invention finds that in the preparation process of the capacitor anode material, after applying a certain pressing force to the aluminum powder slurry, the obtained anode material has a higher porosity than the coating and paving method used in the prior art, so that the obtained capacitor has a more ideal performance.

Description

Technical Field

[0001] The invention belongs to the technical field of capacitors, and in particular relates to a method for preparing a high-porosity anode material. Background Art

[0002] Aluminum electrolytic capacitors are widely used in electronics, communications, energy, automobiles and other fields due to their large capacity and high withstand voltage. High-voltage anode electronic aluminum foil is an important component of aluminum electrolytic capacitors. It usually includes a substrate and a barrier-type oxide film grown on the surface of the substrate by anodization. The film has good dielectric properties and can carry and store charge. Most of the aluminum electrolytic capacitor anode materials in the prior art use traditional corrosion foils. There is an acid corrosion step in its production process, and a large amount of acidic waste liquid is generated, which pollutes the environment.

[0003] In response to this problem, people have also conducted exploration and research in long-term production and life practices. For example, a Chinese invention patent application discloses a method for preparing an anode material for an aluminum electrolytic capacitor [application number: 202311764325.2]. The invention application includes: step S1: providing a plurality of spherical aluminum-containing powders of different particle sizes, and using the spherical aluminum-containing powders to prepare aluminum-containing slurries with different particle size grades, each of which corresponds to a spherical aluminum-containing powder of the particle size; step S2: providing an aluminum foil substrate, and coating the aluminum-containing slurry in step S1 on the surface of the aluminum foil substrate in order of particle size grades from small to large, and after each layer of the aluminum-containing slurry is coated, the aluminum foil substrate coated with the aluminum-containing slurry is dried to form an aluminum foil blank; step S3: sintering the aluminum foil blank to form an initial anode material; step S4: chemically treating the initial anode material to form an oxide layer on the initial anode material to obtain a target anode material.

[0004] Although the invention application forms a target anode material with a layered gradient structure by coating aluminum-containing slurries of different particle sizes on the surface of an aluminum foil substrate layer by layer, thereby improving the specific capacitance of the anode material, the applicant has found that during the preparation process of the aluminum-containing slurry by coating and spreading, the slurry will flow to both sides, making it impossible to maintain a uniform slurry thickness, resulting in the porosity of the anode material still needing to be improved. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a high-porosity anode material in view of the above problems.

[0006] A method for preparing a high-porosity anode material comprises the following steps:

[0007] Step 1: Mix aluminum powder, valve metal oxide powder, binder and solvent, and stir for 5-20 hours to obtain aluminum powder slurry;

[0008] Step 2: pour the aluminum powder slurry prepared in step 1 into a mold, apply a pressing force to the aluminum powder slurry using a pressing plate, and dry it after pressing to obtain an aluminum foil sheet;

[0009] Step 3: Sintering the aluminum foil obtained in step 2 in a protective gas environment to obtain a high-porosity anode material.

[0010] In the above-mentioned method for preparing a high-porosity anode material, the aluminum powder slurry in step 1 is composed of 54-70 parts by mass of aluminum powder, 0.01-2.3 parts by mass of valve metal oxide powder, 4-12 parts by mass of a binder and 27-48 parts by mass of a solvent.

[0011] In the above-mentioned method for preparing a high-porosity anode material, the aluminum powder slurry in step 1 is composed of 60 parts by mass of aluminum powder, 1 part by mass of valve metal oxide powder, 8 parts by mass of binder and 35 parts by mass of solvent.

[0012] In the above-mentioned method for preparing a high-porosity anode material, the particle size of the aluminum powder in step 1 is 2-5 μm.

[0013] In the above method for preparing a high-porosity anode material, the valve metal oxide powder in step 1 is at least one of titanium dioxide, tantalum pentoxide and niobium pentoxide.

[0014] In the above-mentioned method for preparing a high-porosity anode material, the binder in step 1 is at least one of polyvinylidene fluoride, methyl cellulose, ethyl cellulose, trityl cellulose, cyanoethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, aminoethyl cellulose and ethoxy cellulose.

[0015] In the above-mentioned method for preparing a high-porosity anode material, the solvent in step 1 is an aqueous solvent or an organic solvent.

[0016] In the above-mentioned method for preparing a high-porosity anode material, the pressing force in step 2 is 50-300N.

[0017] In the above-mentioned method for preparing a high-porosity anode material, the thickness of the aluminum powder slurry after pressing in step 2 is 135-165 μm.

[0018] In the above-mentioned method for preparing a high-porosity anode material, the protective gas in step three is argon, the sintering temperature is 500-700° C., and the sintering time is 6-10 hours.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] The present invention finds that in the process of preparing capacitor anode materials, after applying a certain pressing force to the aluminum powder slurry, the obtained anode material has a higher porosity than the coating and paving method used in the prior art, so that the obtained capacitor has more ideal performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of a pressing die for extruding aluminum powder slurry according to the present invention;

[0022] Figure 2 This is an electron microscope image of the cross section of the high-porosity anode material prepared in Example 3;

[0023] Figure 3 This is an electron microscope image of the surface of the high-porosity anode material prepared in Example 3;

[0024] In the figure: mold 1, aluminum powder slurry 2, pressing plate 3. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0026] Example 1

[0027] This embodiment provides a method for preparing a high-porosity anode material. Figure 1 As shown, the following steps are included:

[0028] Step 1: Aluminum powder with a particle size of 2 μm, titanium dioxide, polyvinylidene fluoride and a water solvent are mixed together and stirred for 5 hours to obtain aluminum powder slurry 2;

[0029] Step 2: Pour the aluminum powder slurry 2 prepared in step 1 into the mold 1, and use the pressing plate 3 to apply a pressing force of 50N to the aluminum powder slurry 2. After pressing, the thickness of the aluminum powder slurry 2 is 165μm. After pressing, dry it to obtain an aluminum foil sheet;

[0030] Step 3: Sinter the aluminum foil obtained in step 2 in an argon protected environment at a sintering temperature of 500° C. and a sintering time of 6 hours to obtain a high-porosity anode material.

[0031] The aluminum powder slurry is composed of 54 parts of aluminum powder, 2.3 parts of titanium dioxide, 12 parts of polyvinylidene fluoride and 48 parts of water solvent in respective weight parts.

[0032] The average pore size of the high-porosity anode material was measured to be 2.5 μm, and the porosity was 61%.

[0033] Example 2

[0034] This embodiment provides a method for preparing a high-porosity anode material. Figure 1 As shown, the following steps are included:

[0035] Step 1: Aluminum powder with a particle size of 5 μm, tantalum pentoxide, methyl cellulose and a water solvent are mixed and stirred for 20 hours to obtain aluminum powder slurry 2;

[0036] Step 2: Pour the aluminum powder slurry 2 prepared in step 1 into the mold 1, and use the pressing plate 3 to apply a pressing force of 300N to the aluminum powder slurry 2. After pressing, the thickness of the aluminum powder slurry 2 is 155μm. After pressing, dry it to obtain an aluminum foil sheet;

[0037] Step 3: Sinter the aluminum foil obtained in step 2 in an argon protected environment at a sintering temperature of 700° C. for 10 h to obtain a high-porosity anode material.

[0038] The aluminum powder slurry is composed of 70 parts of aluminum powder, 0.01 parts of tantalum pentoxide, 4 parts of methyl cellulose and 27 parts of water solvent in respective weight parts.

[0039] The average pore size of the high-porosity anode material was measured to be 3 μm, and the porosity was 69%.

[0040] Example 3

[0041] This embodiment provides a method for preparing a high-porosity anode material. Figure 1 As shown, the following steps are included:

[0042] Step 1: Aluminum powder with a particle size of 3.5 μm, niobium pentoxide, aminoethyl cellulose and a water solvent are mixed together and stirred for 10 hours to obtain aluminum powder slurry 2;

[0043] Step 2: Pour the aluminum powder slurry 2 prepared in step 1 into the mold 1, and use the pressing plate 3 to apply a pressing force of 150N to the aluminum powder slurry 2. After pressing, the thickness of the aluminum powder slurry 2 is 135μm. After pressing, dry it to obtain an aluminum foil sheet;

[0044] Step 3: Sinter the aluminum foil obtained in step 2 in an argon protected environment at a sintering temperature of 600° C. and a sintering time of 8 h to obtain a high-porosity anode material.

[0045] The aluminum powder slurry is composed of 60 parts of aluminum powder, 1 part of niobium pentoxide, 8 parts of aminoethyl cellulose and 35 parts of water solvent in mass parts.

[0046] The average pore size of the high-porosity anode material was measured to be 4 μm, and the porosity was 84%.

[0047] The cross-sectional electron micrographs and surface electron micrographs of the high-porosity anode material prepared in this embodiment are shown in Figures 1 and 2. Figure 2 and Figure 3 shown.

[0048] Comparative Example 1

[0049] This comparative example provides a method for preparing an anode material, combining Figure 1 As shown, the following steps are included:

[0050] Step 1: Aluminum powder with a particle size of 3.5 μm, niobium pentoxide, aminoethyl cellulose and a water solvent are mixed together and stirred for 10 hours to obtain aluminum powder slurry 2;

[0051] Step 2: Pour the aluminum powder slurry 2 prepared in step 1 into the mold 1, use the die head to spread the aluminum powder slurry 2, adjust the spread thickness to 135 μm, and dry to obtain an aluminum foil;

[0052] Step 3: Sinter the aluminum foil obtained in step 2 in an argon protected environment at a sintering temperature of 600° C. and a sintering time of 8 h to obtain an anode material.

[0053] The aluminum powder slurry is composed of 60 parts of aluminum powder, 1 part of niobium pentoxide, 8 parts of aminoethyl cellulose and 35 parts of water solvent in mass parts.

[0054] The average pore size of the high-porosity anode material was measured to be 1.3 μm, and the porosity was 56%.

[0055] Comparative Example 2

[0056] This comparative example provides a method for preparing an anode material, combining Figure 1 As shown, the following steps are included:

[0057] Step 1: Aluminum powder with a particle size of 3.5 μm, niobium pentoxide, aminoethyl cellulose and a water solvent are mixed together and stirred for 10 hours to obtain aluminum powder slurry 2;

[0058] Step 2: Pour the aluminum powder slurry 2 prepared in step 1 into the mold 1, use the die head to spread the aluminum powder slurry 2, adjust the spread thickness to 155 μm, and dry to obtain an aluminum foil;

[0059] Step 3: Sinter the aluminum foil obtained in step 2 in an argon protected environment at a sintering temperature of 600° C. and a sintering time of 8 h to obtain an anode material.

[0060] The aluminum powder slurry is composed of 60 parts of aluminum powder, 1 part of niobium pentoxide, 8 parts of aminoethyl cellulose and 35 parts of water solvent in mass parts.

[0061] The average pore size of the prepared high-porosity anode material was measured to be 1.2 μm, and the porosity was 55%.

[0062] Application Example 1

[0063] The anode materials prepared in Examples 1-3 and Comparative Examples 1-2 were hydrated, i.e., boiled in pure water in a 2L beaker for 5 min, with the water temperature set at 95°C; and then subjected to chemical treatment, i.e., F1→F2→F3→F4→F5→muffle furnace 520°C, 2min→F5a→soaked in phosphoric acid (70°C, 5min) and then rinsed with pure water→F5a→muffle furnace 520°C, 2min→F5a→soaked in diammonium phosphate (66.3°C, 2min) and then rinsed with pure water. The time and voltage parameters of F1-F5a are shown in the following table:

[0064]

[0065] The data of the chemical foil obtained after chemical treatment are as follows:

[0066]

[0067] Result analysis: From the above experimental results, it can be seen that the capacitor anode material provided by the present invention has a higher porosity, and the electrostatic capacitance of the subsequently prepared formed foil is also more ideal, thereby ensuring that the prepared capacitor has better performance, thus achieving the intended purpose of the present invention.

[0068] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0069] Although the terms such as mold 1, aluminum powder slurry 2, and press plate 3 are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims

1. A method for preparing a high-porosity anode material, characterized in that: The following steps are involved: Step 1: mixing aluminum powder, valve metal oxide powder, a binder and a solvent, and stirring for 5-20 hours to obtain an aluminum powder slurry (2); Step 2: pouring the aluminum powder slurry (2) prepared in step 1 into the mold (1), applying a pressing force to the aluminum powder slurry (2) using a pressing plate (3), and drying after pressing to obtain an aluminum foil sheet; Step 3: Sintering the aluminum foil obtained in step 2 in a protective gas environment to obtain a high-porosity anode material.

2. The method for preparing a high-porosity anode material according to claim 1, characterized in that: The aluminum powder slurry in step 1 is composed of 54-70 parts by mass of aluminum powder, 0.01-2.3 parts by mass of valve metal oxide powder, 4-12 parts by mass of binder and 27-48 parts by mass of solvent.

3. The method for preparing a high-porosity anode material according to claim 2, characterized in that: The aluminum powder slurry in step 1 is composed of 60 parts by mass of aluminum powder, 1 part by mass of valve metal oxide powder, 8 parts by mass of binder and 35 parts by mass of solvent.

4. The method for preparing a high-porosity anode material according to claim 1, characterized in that: The particle size of the aluminum powder in step 1 is 2-5 μm.

5. The method for preparing a high-porosity anode material according to claim 1, characterized in that: The valve metal oxide powder in step 1 is at least one of titanium dioxide, tantalum pentoxide and niobium pentoxide.

6. The method for preparing a high-porosity anode material according to claim 1, characterized in that: The binder in step 1 is at least one of polyvinylidene fluoride, methyl cellulose, ethyl cellulose, trityl cellulose, cyanoethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, aminoethyl cellulose and ethoxy cellulose.

7. The method for preparing a high-porosity anode material according to claim 1, characterized in that: The solvent in step 1 is an aqueous solvent or an organic solvent.

8. The method for preparing a high-porosity anode material according to claim 1, characterized in that: The pressing force in step 2 is 50-300N.

9. The method for preparing a high-porosity anode material according to claim 1, characterized in that: In the step 2, the thickness of the aluminum powder slurry after pressing is 135-165 μm.

10. The method for preparing a high-porosity anode material according to claim 1, characterized in that: The protective gas in step three is argon, the sintering temperature is 500-700° C., and the sintering time is 6-10 hours.

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