A method for preparing a low-cost, low-pollution aluminum electrolytic capacitor anode foil

Abstract

The application discloses a preparation method of a low-cost and low-pollution aluminum electrolytic capacitor anode foil, and comprises the following steps: (1) micro-plasma oxidation is performed on an aluminum foil to obtain an aluminum foil with an aluminum oxide surface layer; (2) the aluminum foil with the aluminum oxide surface layer is cleaned and then dried to obtain a clean aluminum foil; (3) spherical aluminum powder is cold-sprayed on the clean aluminum foil to obtain a blank; and (4) the obtained blank is subjected to water boiling and formation treatment to obtain the aluminum electrolytic capacitor anode foil. The micro-plasma oxidation method is adopted to form micro-channels on the surface of the aluminum foil substrate and simultaneously obtain an aluminum oxide surface layer with good interface combination, so that the specific surface area of the aluminum foil is increased; the cold-spraying technology is further adopted to spray the spherical aluminum powder to the surface of the aluminum foil substrate to form an aluminum powder coating, so that the specific surface area of the coating is increased again; and the subsequent heat treatment process is adopted to oxidize the aluminum powder coating into an aluminum oxide coating, so that the capacitance and bending performance of the aluminum electrolytic capacitor anode foil are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum electrolytic capacitors, and particularly relates to a preparation method of a low-cost and low-pollution aluminum electrolytic capacitor anode foil. BACKGROUND

[0002] As an important device in the electronic industry, electrolytic capacitors have been widely used in the fields of aerospace, rail transportation, industrial control, electronic circuits, new energy, etc. The anode foil is one of the key components of the electrolytic capacitor, and the quality of the anode foil is related to the service life of the electrolytic capacitor, thereby affecting the service life of the entire electronic device.

[0003] At present, the anode foil preparation technology of domestic high-voltage electrolytic capacitors is mostly etching expansion technology. However, this etching foil processing method is complicated, and needs to use sulfuric acid, hydrochloric acid and other acidic etching solutions, resulting in poor foil quality and shortening the service life of the anode foil. And it is difficult to handle the waste acid and waste oil generated during processing and etching, which has great environmental pressure. Compared with etching expansion technology, powder layer electronic foil preparation technology, as a low-pollution electrolytic capacitor anode foil preparation technology, can produce anode foils with high specific surface area and porous structure. And it does not need to be etched during preparation, which is energy-saving, emission-reducing and environmentally friendly. However, the use of organic solvents and binders in the preparation of slurry during the preparation of anode foils by powder layer electronic foil preparation technology still causes light pollution to the environment. For example, the resin binders used in the patent with publication number CN102714098A, such as carboxyl modified polyolefin resin, vinyl acetate resin, and chlorinated ethylene resin, the binders used in the patent with publication number CN114523112A, such as nitrocellulose resin, methyl cellulose, ethyl cellulose, trityl cellulose, and cyanoethyl cellulose, and the binders used in the patent with publication number CN112045190A, such as polystyrene, nitrocellulose, oleic acid, ketone hexadecanone, sorbitol, and fluorine-containing compounds, the organic substances emitted during drying and sintering are harmful to the environment, and these organic substances are difficult to recycle and utilize. In addition, the large use of many organic solvents in the preparation of slurry increases the manufacturing cost of the anode foil to a certain extent.

[0004] Therefore, a low-cost and low-pollution aluminum electrolytic capacitor anode foil preparation method without using solvents is needed. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a low-cost and low-pollution preparation method of an aluminum electrolytic capacitor anode foil in view of the above-mentioned problems of the prior art.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a low-cost and low-pollution preparation method of an aluminum electrolytic capacitor anode foil, which comprises the following steps:

[0007] Step one: micro-plasma oxidation of the aluminum foil to obtain an aluminum foil with an aluminum oxide surface layer; in the micro-plasma oxidation, the aluminum foil is used as an anode, and a stainless steel electrolyte tank is used as a cathode; the aluminum oxide surface layer has micro-channels;

[0008] Step two: cleaning and drying the aluminum foil with the aluminum oxide surface layer obtained in step one to obtain a clean aluminum foil;

[0009] Step three: cold spraying of spherical aluminum powder on the clean aluminum foil obtained in step two to obtain a blank;

[0010] Step four: water boiling and chemical conversion treatment of the blank obtained in step three to obtain an aluminum electrolytic capacitor anode foil.

[0011] The present application uses a micro-plasma oxidation method to prepare small pores on the surface of the aluminum foil substrate to form micro-channels, and then uses a cold spraying technology to spray spherical aluminum powder on the surface of the aluminum foil substrate to form an aluminum powder coating. After heat treatment and chemical conversion treatment, an aluminum electrolytic capacitor anode foil is obtained. Through the micro-plasma oxidation method, small pores are formed on the surface of the aluminum foil, which can make the spherical aluminum powder more easily combined with the aluminum foil during the subsequent cold spraying process, which can also be understood as inlaying. An oxide layer is formed on the surface of the aluminum foil, which makes the surface of the aluminum foil not easy to be damaged during cold spraying. Through the cold spraying technology, a part of the spherical aluminum powder is inlaid into the micro-channels, which mainly supports the micro-channel structure to prevent it from deforming. The particle size of this part of the aluminum powder is basically equal to the diameter of the micro-channels. The other part is finer aluminum powder, which is accumulated in the micro-channels during the spraying process to increase the specific surface area of the foil. This can effectively increase the specific surface area of the foil and improve the capacitance performance of the foil. At the same time, the use of organic solvents, adhesives, and acid and alkali corrosion and removal processes is avoided, which is simple and controllable, friendly to the environment, and greatly saves the production cost.

[0012] The preparation method of the low-cost and low-pollution aluminum electrolytic capacitor anode foil has the characteristics that the thickness of the aluminum foil in step one is 30-60 microns, and the mass purity is greater than 99.99%. The thickness of the aluminum electrolytic capacitor anode foil is ensured by controlling the thickness of the aluminum foil, and the capacitor leakage current of the aluminum electrolytic capacitor anode foil is effectively reduced by limiting the purity of the aluminum foil.

[0013] The preparation method of the low-cost and low-pollution aluminum electrolytic capacitor anode foil has the characteristics that the micro-plasma oxidation in step one does not use sodium-containing electrolyte, and the electrolyte is silicate electrolyte, aluminate electrolyte or phosphate electrolyte. The silicate electrolyte, aluminate electrolyte and phosphate electrolyte effectively reduce the capacitor leakage current of the aluminum electrolytic capacitor anode foil.

[0014] The preparation method of the low-cost and low-pollution aluminum electrolytic capacitor anode foil has the characteristics that the micro-plasma oxidation in step one uses electrolysis for 10-60 seconds, the voltage is 400-700 V, the duty cycle is 20-80%, the electrolyte temperature is 20-40 DEG C, the thickness of the aluminum oxide surface layer is 0.1-5 microns, and the diameter of the micro-channel is 5-100 microns. The size of the micro-channel is effectively controlled by limiting the parameters of the micro-plasma oxidation method, so that the number of 100-40,000 micro-channels per square millimeter of the aluminum foil surface is obtained, thereby effectively improving the capacitance of the aluminum electrolytic capacitor anode foil.

[0015] The preparation method of the low-cost and low-pollution aluminum electrolytic capacitor anode foil has the characteristics that the cleaning process in step two is water washing in a deionized water tank. The surface residual electrolyte is removed by water washing.

[0016] The preparation method of the low-cost and low-pollution aluminum electrolytic capacitor anode foil has the characteristics that the particle size of the spherical aluminum powder in step three is less than 50 microns, and the mass purity is greater than 99.99%. The aluminum powder has a high specific surface area by limiting the particle size of the aluminum powder, which is beneficial to improve the capacitance of the aluminum electrolytic capacitor anode foil, and the capacitor leakage current of the aluminum electrolytic capacitor anode foil is effectively reduced by limiting the purity of the aluminum powder.

[0017] The preparation method of the low-cost and low-pollution aluminum electrolytic capacitor anode foil has the characteristics that the cold spraying in step three adopts helium as the working gas, the carrier gas pressure is 0.5MPa-0.98MPa, the carrier gas temperature is 200-400 DEG C, the spraying thickness is 40-100 mu m, and the cold spraying is double-sided spraying on the aluminum foil.

[0018] The preparation method of the low-cost and low-pollution aluminum electrolytic capacitor anode foil has the characteristics that the cold spraying in step three adopts helium as the working gas, the carrier gas pressure is 0.5MPa-0.98MPa, the carrier gas temperature is 200-400 DEG C, the spraying thickness is 40-100 mu m, and the cold spraying is double-sided spraying on the aluminum foil.

[0019] The preparation method of the low-cost and low-pollution aluminum electrolytic capacitor anode foil has the characteristics that the cold spraying in step three adopts helium as the working gas, the carrier gas pressure is 0.5MPa-0.98MPa, the carrier gas temperature is 200-400 DEG C, the spraying thickness is 40-100 mu m, and the cold spraying is double-sided spraying on the aluminum foil.

[0020] The preparation method of the low-cost and low-pollution aluminum electrolytic capacitor anode foil has the characteristics that the cold spraying in step three adopts helium as the working gas, the carrier gas pressure is 0.5MPa-0.98MPa, the carrier gas temperature is 200-400 DEG C, the spraying thickness is 40-100 mu m, and the cold spraying is double-sided spraying on the aluminum foil. 2 .

[0021] Compared with the prior art, the present application has the following advantages:

[0022] 1. The micro-plasma oxidation method is used to prepare micro holes on the surface of the aluminum foil substrate, form micro channels, and make the spherical aluminum powder more easily combined with the aluminum foil in the subsequent cold spraying process.

[0023] 2、The preparation method of the aluminum electrolytic capacitor anode foil of the application avoids the use of strong acid and strong alkali, reduces the removal process, is good for the environment, is simple, greatly saves the production cost, avoids the use of organic solvents and binders, saves the sintering process, reduces the preparation cost, reduces the pollution to the environment, and ensures the capacitance performance of the aluminum electrolytic capacitor anode foil.

[0024] 3、The micro plasma oxidation method is used to prepare micro holes on the surface of the aluminum foil substrate, form micro channels, and form an oxidation layer, thereby replacing the sand blasting surface treatment, reducing the damage of sand blasting to the surface of the aluminum foil, and ensuring the quality of the aluminum electrolytic capacitor anode foil.

[0025] The technical solutions of the application are further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The SEM image of the blank obtained in Example 1 of the application. DETAILED DESCRIPTION

[0027] Example 1

[0028] This example includes the following steps:

[0029] Step one, micro plasma oxidation is performed on the aluminum foil to obtain an aluminum foil with an aluminum oxide surface layer; the thickness of the aluminum foil is 30 μm, and the mass purity is 99.99%; in the micro plasma oxidation, the aluminum foil is used as an anode, a stainless steel electrolyte tank is used as a cathode, and an electrolyte is a mixed solution of KOH:K2SiO3:H2O with a mass ratio of 1:10:989; the electrolysis time in the micro plasma oxidation is 30 s, the voltage is 648 V, the duty cycle is 50%, and the electrolyte temperature is 30 DEG C; the aluminum oxide surface layer has micro channels; the thickness of the aluminum oxide surface layer is 2.5 μm, and the diameter of the micro channels is 6 μm;

[0030] Step two, the aluminum foil with the aluminum oxide surface layer obtained in step one is washed with water in a deionized water tank and then dried to obtain a clean aluminum foil;

[0031] Step three, spherical aluminum powder is cold sprayed on the clean aluminum foil obtained in step two to obtain a blank; the particle size of the spherical aluminum powder is 10 μm, and the mass purity is 99.99%; helium gas is used as a working gas in the cold spraying, the carrier gas pressure is 0.6 MPa, the carrier gas temperature is 260 DEG C, the spraying thickness is 50 μm, and the aluminum foil is sprayed on both sides by the cold spraying; the powder feeding rate of the cold spraying is 0.004 g / s, the spraying distance is 20 mm, and the moving speed of the spray gun is 8 mm / s.

[0032] Step four, the blank body obtained in step three is subjected to boiling and formation treatment to obtain an aluminum electrolytic capacitor anode foil; the boiling uses deionized water, the boiling time is 12 min, and the boiling temperature is 95℃; in the formation treatment, the formation solution is a boric acid solution with a mass concentration of 18%, the temperature of the formation solution is 90℃, the formation voltage is 520V, and the current density is 0.05A / cm 2 .

[0033] Figure 1 The SEM image of the blank body obtained in this embodiment can be seen from Figure 1 , and it can be seen that the holes in the figure are micropores formed after cold spraying. The existence of such micropores can improve the bending performance of the foil.

[0034] Example 2

[0035] This embodiment includes the following steps:

[0036] Step one, an aluminum foil is subjected to micro-plasma oxidation to obtain an aluminum foil with an aluminum oxide surface layer; the thickness of the aluminum foil is 60μm, and the mass purity is 99.99%; in the micro-plasma oxidation, the aluminum foil is used as an anode, a stainless steel electrolyte tank is used as a cathode, and an electrolyte is a mixed solution of KOH:K3PO4:H2O with a mass ratio of 1:10:989; the micro-plasma oxidation uses an electrolysis time of 50s, a voltage of 700V, a duty cycle of 80%, and an electrolyte temperature of 35℃; the aluminum oxide surface layer has micro-channels; the thickness of the aluminum oxide surface layer is 4μm, and the diameter of the micro-channels is 20μm;

[0037] Step two, the aluminum foil with the aluminum oxide surface layer obtained in step one is washed with deionized water and then dried to obtain a clean aluminum foil;

[0038] Step three, spherical aluminum powder is cold sprayed on the clean aluminum foil obtained in step two to obtain a blank body; the particle size of the spherical aluminum powder is 40μm, and the mass purity is 99.99%; the cold spraying uses helium as a working gas, the carrier gas pressure is 0.5MPa, the carrier gas temperature is 400℃, the spraying thickness is 40μm, and the aluminum foil is subjected to double-sided spraying; the cold spraying has a powder feeding rate of 0.002g / s, a spraying distance of 15mm, and a spraying gun moving speed of 6mm / s;

[0039] Step four, the blank body obtained in step three is subjected to boiling and formation treatment to obtain an aluminum electrolytic capacitor anode foil; the boiling uses deionized water, the boiling time is 20min, and the boiling temperature is 90℃; in the formation treatment, the formation solution is a boric acid solution with a mass concentration of 20%, the temperature of the formation solution is 100℃, the formation voltage is 520V, and the current density is 0.05A / cm 2.

[0040] Example 3

[0041] The embodiment comprises the following steps:

[0042] Step one, micro-plasma oxidation of aluminum foil to obtain an aluminum foil with an alumina surface layer; the thickness of the aluminum foil is 40 μm, and the mass purity is 99.99%; in the micro-plasma oxidation, the aluminum foil is used as an anode, a stainless steel electrolyte tank is used as a cathode, and an aluminate electrolyte is used as an electrolyte; the electrolysis time of the micro-plasma oxidation is 60 s, the voltage is 600 V, the duty cycle is 20%, and the electrolyte temperature is 20℃; the alumina surface layer has micro-channels; the thickness of the alumina surface layer is 4 μm, and the diameter of the micro-channels is 18 μm;

[0043] Step two, the aluminum foil with an alumina surface layer obtained in step one is placed in a deionized water tank for water washing and then dried to obtain a clean aluminum foil;

[0044] Step three, cold spraying of spherical aluminum powder on the clean aluminum foil obtained in step two to obtain a green body; the particle size of the spherical aluminum powder is 20 μm, and the mass purity is 99.99%; the cold spraying uses helium as a working gas, the carrier gas pressure is 0.98 MPa, the carrier gas temperature is 200℃, the spraying thickness is 100 μm, and the cold spraying is performed on both sides of the aluminum foil; the powder feeding rate of the cold spraying is 0.1 g / s, the spraying distance is 30 mm, and the spraying gun moving speed is 2 mm / s;

[0045] Step four, water boiling and formation treatment of the green body obtained in step three to obtain an aluminum electrolytic capacitor anode foil; deionized water is used for water boiling, the water boiling time is 10 min, and the water boiling temperature is 100℃; in the formation treatment, the formation solution is a boric acid solution with a mass concentration of 16%, the temperature of the formation solution is 80℃, the formation voltage is 520 V, and the current density is 0.05 A / cm 2 .

[0046] Example 4

[0047] The embodiment comprises the following steps:

[0048] Step one, the aluminum foil is micro-plasma oxidized to obtain an aluminum foil with an alumina surface layer; the thickness of the aluminum foil is 50 μm, and the mass purity is 99.99%; in the micro-plasma oxidation, the aluminum foil is used as an anode, a stainless steel electrolyte tank is used as a cathode, and an electrolyte is a mixed solution of KOH:K3PO4:H2O with a mass ratio of 1:10:989; the electrolysis time of the micro-plasma oxidation is 40 s, the voltage is 400 V, the duty cycle is 60%, and the electrolyte temperature is 25°C; the alumina surface layer has micro-channels; the thickness of the alumina surface layer is 1 μm, and the diameter of the micro-channels is 5 μm;

[0049] Step two, the aluminum foil with the alumina surface layer obtained in step one is washed with deionized water and then dried to obtain a clean aluminum foil;

[0050] Step three, spherical aluminum powder is cold sprayed on the clean aluminum foil obtained in step two to obtain a blank; the particle size of the spherical aluminum powder is 30 μm, and the mass purity is 99.99%; helium gas is used as a working gas in the cold spraying, the carrier gas pressure is 0.7 MPa, the carrier gas temperature is 300°C, the spraying thickness is 90 μm, and the aluminum foil is sprayed on both sides by the cold spraying; the powder feeding rate of the cold spraying is 0.05 g / s, the spraying distance is 25 mm, and the spraying gun moving speed is 4 mm / s;

[0051] Step four, the blank obtained in step three is subjected to water boiling and chemical conversion treatment to obtain an aluminum electrolytic capacitor anode foil; deionized water is used for water boiling, the water boiling time is 15 min, and the water boiling temperature is 98°C; in the chemical conversion treatment, a chemical conversion solution is a boric acid solution with a mass concentration of 15%, the temperature of the chemical conversion solution is 98°C, the chemical conversion voltage is 520 V, and the current density is 0.05 A / cm 2 .

[0052] Example 5

[0053] This example includes the following steps:

[0054] Step one, the aluminum foil is micro-plasma oxidized to obtain an aluminum foil with an alumina surface layer; the thickness of the aluminum foil is 45 μm, and the mass purity is 99.99%; in the micro-plasma oxidation, the aluminum foil is used as an anode, a stainless steel electrolyte tank is used as a cathode, and an electrolyte is a mixed solution of KOH:K3PO4:H2O with a mass ratio of 1:10:989; the electrolysis time of the micro-plasma oxidation is 10 s, the voltage is 500 V, the duty cycle is 40%, and the electrolyte temperature is 40°C; the alumina surface layer has micro-channels; the thickness of the alumina surface layer is 2 μm, and the diameter of the micro-channels is 6 μm;

[0055] Step two, the aluminum foil with the alumina surface layer obtained in step one is washed with deionized water and then dried to obtain a clean aluminum foil;

[0056] Step three, cold spraying spherical aluminum powder on the clean aluminum foil obtained in step two to obtain a blank; the particle size of the spherical aluminum powder is 40 μm, and the mass purity is 99.99%; the cold spraying adopts helium as a working gas, the carrier gas pressure is 0.8 MPa, the carrier gas temperature is 350 ℃, the spraying thickness is 60 μm, and the cold spraying is double-sided spraying on the aluminum foil; the powder feeding rate of the cold spraying is 0.008 g / s, the spraying distance is 20 mm, and the spraying gun moving speed is 10 mm / s;

[0057] Step four, water boiling and formation treatment are performed on the blank obtained in step three to obtain an aluminum electrolytic capacitor anode foil; the water boiling adopts deionized water, the water boiling time is 20 min, and the water boiling temperature is 100 ℃; in the formation treatment, the formation solution is a boric acid solution with a mass concentration of 10%, the temperature of the formation solution is 95 ℃, the formation voltage is 520 V, and the current density is 0.05 A / cm 2 .

[0058] Example 6

[0059] The embodiment comprises the following steps:

[0060] Step one, micro-plasma oxidation is performed on an aluminum foil to obtain an aluminum foil with an alumina surface layer; the thickness of the aluminum foil is 55 μm, and the mass purity is 99.99%; in the micro-plasma oxidation, the aluminum foil is used as an anode, a stainless steel electrolyte tank is used as a cathode, and an electrolyte is a mixed solution of KOH, K2SiO3 and H2O with a mass ratio of 1:10:989; the electrolysis time in the micro-plasma oxidation is 20 s, the voltage is 450 V, the duty cycle is 30%, and the electrolyte temperature is 30 ℃; the alumina surface layer has micro-channels; the thickness of the alumina surface layer is 2 μm, and the diameter of the micro-channels is 10 μm;

[0061] Step two, the aluminum foil with the alumina surface layer obtained in step one is washed with deionized water and then dried to obtain a clean aluminum foil;

[0062] Step three, cold spraying spherical aluminum powder on the clean aluminum foil obtained in step two to obtain a blank; the particle size of the spherical aluminum powder is 40 μm, and the mass purity is 99.99%; the cold spraying adopts helium as a working gas, the carrier gas pressure is 0.8 MPa, the carrier gas temperature is 350 ℃, the spraying thickness is 60 μm, and the cold spraying is double-sided spraying on the aluminum foil; the powder feeding rate of the cold spraying is 0.008 g / s, the spraying distance is 20 mm, and the spraying gun moving speed is 10 mm / s;

[0063] Step four, the blank body obtained in step three is subjected to boiling and formation treatment to obtain an aluminum electrolytic capacitor anode foil; the boiling adopts deionized water, the boiling time is 17 min, and the boiling temperature is 93℃; in the formation treatment, the formation solution is a boric acid solution with a mass concentration of 12%, the temperature of the formation solution is 85℃, the formation voltage is 520V, and the current density is 0.05A / cm 2 .

[0064] Example 7

[0065] This example includes the following steps:

[0066] Step one, an aluminum foil is subjected to micro-plasma oxidation to obtain an aluminum foil with an alumina surface layer; the thickness of the aluminum foil is 35μm, and the mass purity is 99.99%; in the micro-plasma oxidation, the aluminum foil is used as an anode, a stainless steel electrolyte tank is used as a cathode, and an electrolyte is a mixed solution of KOH:K2SiO3:H2O with a mass ratio of 1:10:989; the electrolysis time in the micro-plasma oxidation is 35s, the voltage is 550V, the duty cycle is 70%, and the electrolyte temperature is 30℃; the alumina surface layer has micro-channels; the thickness of the alumina surface layer is 0.1μm, and the diameter of the micro-channels is 5μm;

[0067] Step two, the aluminum foil with the alumina surface layer obtained in step one is washed with deionized water and then dried to obtain a clean aluminum foil;

[0068] Step three, spherical aluminum powder is cold sprayed on the clean aluminum foil obtained in step two to obtain a blank body; the particle size of the spherical aluminum powder is 25μm, and the mass purity is 99.99%; the cold spraying adopts helium as a working gas, the carrier gas pressure is 0.9MPa, the carrier gas temperature is 250℃, the spraying thickness is 80μm, and the aluminum foil is sprayed on both sides by the cold spraying; the powder feeding rate of the cold spraying is 0.03g / s, the spraying distance is 20mm, and the spraying gun moving speed is 7mm / s;

[0069] Step four, the blank body obtained in step three is subjected to boiling and formation treatment to obtain an aluminum electrolytic capacitor anode foil; the boiling adopts deionized water, the boiling time is 15min, and the boiling temperature is 94℃; in the formation treatment, the formation solution is a boric acid solution with a mass concentration of 17%, the temperature of the formation solution is 90℃, the formation voltage is 520V, and the current density is 0.05A / cm 2 .

[0070] Example 8

[0071] This example includes the following steps:

[0072] Step one, the aluminum foil is subjected to micro-plasma oxidation to obtain an aluminum foil with an alumina surface layer; the thickness of the aluminum foil is 55 μm, and the mass purity is 99.99%; in the micro-plasma oxidation, the aluminum foil is used as an anode, a stainless steel electrolyte tank is used as a cathode, and an electrolyte is a mixed solution of KOH:K3PO4:H2O with a mass ratio of 1:10:989; the electrolysis time in the micro-plasma oxidation is 45 s, the voltage is 6500 V, the duty cycle is 50%, and the electrolyte temperature is 30℃; the alumina surface layer has micro-channels; the thickness of the alumina surface layer is 5 μm, and the diameter of the micro-channels is 100 μm;

[0073] Step two, the aluminum foil with the alumina surface layer obtained in step one is washed with deionized water and then dried to obtain a clean aluminum foil;

[0074] Step three, spherical aluminum powder is cold sprayed on the clean aluminum foil obtained in step two to obtain a blank; the particle size of the spherical aluminum powder is 35 μm, and the mass purity is 99.99%; helium is used as a working gas in the cold spraying, the carrier gas pressure is 0.75 MPa, the carrier gas temperature is 330℃, the spraying thickness is 50 μm, and the aluminum foil is sprayed on both sides; the powder feeding rate of the cold spraying is 0.08 g / s, the spraying distance is 25 mm, and the spraying gun moving speed is 3 mm / s;

[0075] Step four, the blank obtained in step three is subjected to water boiling and chemical conversion treatment to obtain an aluminum electrolytic capacitor anode foil; deionized water is used in the water boiling, the water boiling time is 18 min, and the water boiling temperature is 99℃; in the chemical conversion treatment, the chemical conversion solution is a boric acid solution with a mass concentration of 12%, the temperature of the chemical conversion solution is 95℃, the chemical conversion voltage is 520 V, and the current density is 0.05 A / cm 2 .

[0076] The aluminum electrolytic capacitor anode foils prepared in Examples 1-8 are tested by an LCR tester, and the obtained static specific capacity is shown in Table 1.

[0077] Table 1: Static specific capacity of the aluminum electrolytic capacitor anode foils prepared in Examples 1-8

[0078] Examples Static capacitance (pF / cm2) 1 0.84 2 0.87 3 0.82 4 0.81 5 0.80 6 0.85 7 0.81 8 0.83

[0079] As can be seen from Table 1, the static specific capacity of the aluminum electrolytic capacitor anode foils prepared in the present application is greater than 0.80 μF / cm 2 , and the highest can reach 0.87 μF / cm 2 .

Claims

1. A method for preparing anode foil for a low-cost, low-pollution aluminum electrolytic capacitor, characterized in that, The method includes the following steps: Step 1: Perform micro-plasma oxidation on aluminum foil to obtain aluminum foil with an aluminum oxide surface layer; in the micro-plasma oxidation, the aluminum foil is used as the anode and the stainless steel electrolyte tank is used as the cathode; the aluminum oxide surface layer has microchannels. Step 2: Clean and dry the aluminum foil with an alumina surface obtained in Step 1 to obtain clean aluminum foil; Step 3: Cold spray spherical aluminum powder onto the clean aluminum foil obtained in Step 2 to obtain a blank; Step 4: Boil and form the blank obtained in Step 3 to obtain the anode foil of aluminum electrolytic capacitor.

2. The method for preparing a low-cost, low-pollution aluminum electrolytic capacitor anode foil according to claim 1, characterized in that, The aluminum foil mentioned in step one has a thickness of 30μm~60μm and a purity greater than 99.99%.

3. The method for preparing a low-cost, low-pollution aluminum electrolytic capacitor anode foil according to claim 1, characterized in that, The electrolyte used in the micro-plasma oxidation in step one does not contain sodium. The electrolyte is a silicate electrolyte, an aluminate electrolyte, or a phosphate electrolyte.

4. The method for preparing the anode foil of a low-cost, low-pollution aluminum electrolytic capacitor according to claim 1, characterized in that, The electrolysis time for the micro-plasma oxidation in step one is 10s~60s, the voltage is 400V~700V, the duty cycle is 20%~80%, and the electrolyte temperature is 20℃~40℃; the alumina surface layer thickness is 0.1μm~5μm, and the diameter of the microchannel is 5μm~100μm.

5. The method for preparing a low-cost, low-pollution aluminum electrolytic capacitor anode foil according to claim 1, characterized in that, The cleaning process described in step two involves rinsing the item in a deionized water tank.

6. The method for preparing a low-cost, low-pollution aluminum electrolytic capacitor anode foil according to claim 1, characterized in that, The spherical aluminum powder mentioned in step three has a particle size of less than 50 μm and a purity of more than 99.99%.

7. The method for preparing a low-cost, low-pollution aluminum electrolytic capacitor anode foil according to claim 1, characterized in that, In step three, the cold spraying uses helium as the working gas, with a carrier gas pressure of 0.5MPa~0.98MPa, a carrier gas temperature of 200℃~400℃, and a spraying thickness of 40μm~100μm. The cold spraying is applied to both sides of the aluminum foil.

8. The method for preparing a low-cost, low-pollution aluminum electrolytic capacitor anode foil according to claim 1, characterized in that, The powder feed rate for cold spraying in step three is 0.002 g / s to 0.1 g / s, the spray distance is 15 mm to 30 mm, and the spray gun moving speed is 2 mm / s to 10 mm / s.

9. The method for preparing a low-cost, low-pollution aluminum electrolytic capacitor anode foil according to claim 1, characterized in that, Step four involves boiling in deionized water for 10-20 minutes at a temperature of 90-100°C.

10. The method for preparing a low-cost, low-pollution aluminum electrolytic capacitor anode foil according to claim 1, characterized in that, In step four, the formation process uses a boric acid solution with a mass concentration of 10% to 20%, a formation temperature of 80°C to 100°C, a formation voltage of 520V, and a current density of 0.05A / cm². 2 .

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