Aluminum foil with microporous structure and preparation method thereof

Abstract

The invention discloses an aluminum foil with a micropore structure, the aluminum foil is a rolled aluminum foil, the pore size of the micropore is 0-150 microns, and the micropore comprises a blind hole and a through hole. The edges of the holes are smooth, no obvious particles or convex substances exist, and the surfaces are free of burrs and oxidation; compared with the traditional microporous aluminum foil, the product does not have the quality problems of burrs, oxidation and the like, and the overall quality and reliability of the product are improved.

Description

Technical field:

[0001] The invention belongs to the technical field of metal foil processing, and in particular relates to an aluminum foil with a microporous structure and a preparation method of the aluminum foil. Background technology:

[0002] Microporous aluminum foil, as an important material, plays a key role in battery manufacturing, especially as a current collector in lithium-ion batteries and other types of electrochemical energy storage devices.

[0003] The existing technical methods for preparing microporous aluminum foil have their own shortcomings. Chemical etching is a method of forming micropores by removing part of the material on the surface of the aluminum foil through chemical reaction. Although this method is relatively low in cost, it has obvious disadvantages: Complex solution: The chemical reagents used usually contain multiple components, the ratio requirements are strict, and the operation process is complicated. Not environmentally friendly: The waste liquid generated contains harmful substances, and improper treatment will cause environmental pollution. Difficult to control the pore size: Due to the non-uniformity of the chemical reaction, it is difficult to accurately control the size and distribution of the pores. Mechanical methods include physical processing methods such as stamping and drilling, which can directly form the required holes on the aluminum foil. However, this technology also faces some challenges: Easy to generate burrs: Burrs may be left on the edge of the hole during mechanical processing, which poses a threat to the insulation performance and overall safety of the battery. Difficult processing: Mechanical methods are often difficult to achieve for high-density small hole processing. Low efficiency: The processing time of a single hole is long, which is not conducive to large-scale production. The laser method uses a high-energy laser beam to quickly evaporate the material on the aluminum foil to form holes. Although this method has the advantages of fast processing speed and controllable aperture, it also has some disadvantages: It may cause oxidation: During laser processing, high temperature may cause oxidation on the surface of aluminum foil, affecting its conductivity. High cost: The investment and operating costs of laser equipment are relatively high, which increases the cost of the final product. Heat-affected zone: Laser processing will produce a heat-affected zone, which may affect the properties of surrounding materials. These shortcomings limit its wide application in the battery field.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention:

[0005] The object of the present invention is to provide an aluminum foil with a microporous structure, thereby overcoming the defects in the above-mentioned prior art.

[0006] To achieve the above purpose, the present invention provides an aluminum foil with a microporous structure, wherein the aluminum foil is a rolled aluminum foil, the micropore size is 0 to 150 μm, and the micropores include blind holes and through holes. Blind hole aluminum foil means that the holes on the aluminum foil do not penetrate the entire foil material, and only form holes of a certain depth on the surface. Through hole aluminum foil means that the holes penetrate the foil material deeply.

[0007] Preferably, in the above technical solution, the pore size is 0.4-50um, and the pore density is 2000-20000 / cm 2 , the hole depth is 1-10um.

[0008] A method for preparing an aluminum foil with a microporous structure, the specific steps are as follows:

[0009] a. preparing a water-soluble additive solution I, wherein the water-soluble additive is one or a combination of hydrolyzed protein peptide, sodium carboxymethyl cellulose, polyvinyl pyrrolidone, cellulose acetate, cellulose ether, starch, polyvinyl alcohol, polyethylene glycol, polypropylene glycol, gelatin, carboxymethyl chitosan, polyacrylamide, polyacrylic acid, xanthan gum, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate), polymerized vinyl sulfonic acid, polyacrylamide, polyaniline, sodium 3-mercapto-1-propane sulfonate, sodium polydisulfide propane sulfonate, sodium 3-(benzothiazole-2-mercapto)-propane sulfonate, isothiourea propanesulfonic acid inner salt, sodium allyl sulfonate, benzotriazole, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, and common amino acids such as glycine, tryptophan, and aspartic acid;

[0010] b. Prepare a salt solution II of a certain concentration; the salt solution II is one or a combination of sodium chloride, potassium chloride, potassium bromide, sodium bromide, potassium iodide, sodium iodide, potassium perchlorate, potassium sulfate, copper chloride, copper sulfate, sodium carbonate, ammonium nitrate, ammonium bicarbonate, ferric chloride, potassium hydroxide, sodium hydroxide, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, phosphoric acid, formic acid, oxalic acid, and chloroacetic acid;

[0011] c. Mixing solution I and salt solution II in a certain proportion to form solution III for preparing microporous aluminum foil in the next step, wherein the concentration of the water-soluble additive in the solution is 1-500 ppm after mixing;

[0012] d. Immerse the original aluminum foil IV in the solution III, and use air blowing or stirring to make the solution III in a convection state;

[0013] e. After a specific reaction time, the aluminum foil IV is taken out, cleaned and dried to obtain a microporous aluminum foil V.

[0014] When the aluminum foil is immersed in solution III, the additive molecules can be adsorbed on the surface of the aluminum foil. The additives with larger molecular weight can be evenly adsorbed on the surface of the aluminum by virtue of functional groups such as hydroxyl, amino, carboxyl, and thiol. The additives with smaller molecular weight can be supplemented with the macromolecules for adsorption on the surface space of the aluminum foil, thereby achieving coverage of the surface of the aluminum foil. During the reaction, the ions in solution III react with the aluminum surface. Al and the Al2O3 on the surface are amphoteric substances, which can react with acids and bases. Al is a reducing metal and can react with oxidizing ions, such as Cu 2+ 、Ag + , Fe 3+ wait.

[0015] Reaction with acids:

[0016] Aluminum reacts with strong acids (such as hydrochloric acid, sulfuric acid, etc.) to generate aluminum ions and hydrogen:

[0017] Al(s)+3HCl(aq)→AlCl3(aq)+3 / 2H2(g),

[0018] 2Al(s)+3H2SO4(aq)→Al2(SO4)3(aq)+3H2(g);

[0019] Reaction with base:

[0020] Aluminum reacts with a strong base (such as sodium hydroxide) to produce aluminates and hydrogen:

[0021] 2Al(s)+2NaOH(aq)+6H2O(l)→2NaAl(OH)4+3H2(g);

[0022] Reaction of oxide Al2O3 with acid and alkali:

[0023] Alumina (Al2O3) reacts with strong acid to generate aluminum ions:

[0024] Al2O3(s)+6HCl(aq)→2AlCl3(aq)+3H2O(l);

[0025] Alumina reacts with strong base to form aluminate:

[0026] Al2O3(s)+2NaOH(aq)+3H2O(l)→2NaAl(OH)4;

[0027] The additive coverage on a small part of the aluminum foil surface is destroyed, resulting in holes. The concentration of ions that react with Al in the solution is related to the degree of damage to the additive coverage. When the total concentration of ions that can react with Al in the solution is 0.01 mol / L to 5 mol / L, 0.2% to 15% of the additive coverage is destroyed.

[0028] Copper ion (Cu 2+ ):

[0029] When aluminum metal is immersed in a solution containing copper ions, the following reaction occurs:

[0030] Al(s)+Cu 2+ (aq)→Al 3+ (aq)+Cu(s);

[0031] This reaction is a redox reaction, aluminum is oxidized, and copper ions are reduced to metallic copper precipitates.

[0032] Silver ion (Ag+):

[0033] A similar redox reaction occurs when aluminum metal is immersed in a solution containing silver ions:

[0034] 2Al(s)+3Ag + (aq)→2Al 3+ (aq)+3Ag(s);

[0035] Aluminum is oxidized and silver ions are reduced to metallic silver precipitates.

[0036] Iron ion (Fe3+):

[0037] In acidic solution, aluminum can also react with trivalent iron ions (Fe3+):

[0038] 2Al(s)+6H + (aq)+2Fe 3+ (aq)→2Al 3+ (aq)+2Fe 2+ (aq)+3H2(g);

[0039] The reaction produces ferrous ions and hydrogen gas.

[0040] When the solution contains Cl - 、F -When there are anions, these ions have a small radius and high penetration, which can easily destroy the oxide film and produce corrosion holes. By controlling the type, molecular weight, concentration of additives, as well as the composition, concentration, pH, temperature, reaction time, and solution convection speed of the salt solution, microporous aluminum foil with different pore sizes and pore structures can be obtained. The pore size is related to the molecular weight and concentration of the additive. The larger the molecular weight and the higher the concentration, the smaller the pore size; the pore depth is related to the concentration of ions in the solution, the temperature, the reaction time, and the solution convection speed. The greater the ion concentration, the higher the temperature, the reaction time, and the greater the solution convection speed, the deeper the pore depth; the pore density is related to the additive concentration and the salt ion concentration. The smaller the additive concentration and the higher the salt ion concentration, the greater the pore density; Al is an amphoteric metal. In the range of pH <4.5 and pH >8.5, the higher the H+ or OH- concentration, the faster the reaction rate.

[0041] Preferably, in the above technical scheme, the water-soluble additive solution I contains macromolecules and small molecules with amino, hydroxyl, thiol, carboxyl, ether bond, aldehyde, and nitrogen-containing functional groups, wherein macromolecules refer to molecules with a molecular weight greater than 1000, and small molecules refer to molecules with a molecular weight less than 1000.

[0042] Preferably, in the above technical solution, a water-soluble additive solution I is prepared, and can be heated or stirred at room temperature according to the solubility of the additive molecules.

[0043] Preferably, in the above technical solution, the concentration of the salt solution II is 0.01 mol / L to 1 mol / L.

[0044] Preferably, in the above technical solution, the pH range of the mixed solution III is less than 4.5, or greater than 8.5.

[0045] Preferably, in the above technical solution, in step e, the specific reaction time is 10s to 60min.

[0046] Preferably, in the above technical solution, the additive solution I in step a can also be first coated on the surface of the aluminum foil to form a film, and then the film-formed aluminum foil is immersed in the salt solution II to perform steps d and e.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] Simple operation: The preparation process is simple and can be completed by simply preparing the solution and allowing it to flow. No complicated operating steps or equipment are required.

[0049] Environmentally friendly: The solution has simple ingredients and does not contain substances harmful to the environment. It meets environmental protection requirements and is conducive to sustainable production.

[0050] Controllable pore structure: The pore size, pore depth and pore density can be precisely controlled. Different micropore structures can be customized according to specific needs.

[0051] Achieve mass production: After simple test verification, large-scale mass production can be achieved to ensure product stability and reliability.

[0052] Excellent product quality: Please refer to the instructions attached Figure 2 In the scanning electron microscope image, the edge of the hole is smooth, there are no obvious particles or protrusions, and there is no burr or oxidation on the surface; compared with traditional microporous aluminum foil, this product does not have quality problems such as burrs and oxidation, which improves the overall quality and reliability of the product.

[0053] High production efficiency: The preparation process is simple and efficient, the production efficiency is high, it can meet the needs of large-scale production and reduce production costs. Description of the drawings:

[0054] Figure 1 This is the electron microscope image of the aluminum foil hole-forming surface;

[0055] Figure 2 This is a scanning electron microscope image of a single hole on the surface of aluminum foil. Specific implementation method:

[0056] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0057] A method for preparing an aluminum foil with a microporous structure, the specific steps are as follows:

[0058] a. Prepare a water-soluble additive solution I, which can be heated or stirred at room temperature according to the solubility of the additive molecule. The water-soluble additive is one or a combination of hydrolyzed protein peptides, sodium carboxymethyl cellulose, polyvinyl pyrrolidone, cellulose acetate, cellulose ether, starch, polyvinyl alcohol, polyethylene glycol, polypropylene glycol, gelatin, carboxymethyl chitosan, polyacrylamide, polyacrylic acid, xanthan gum, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate), polymerized vinyl sulfonic acid, polyacrylamide, polyaniline, sodium 3-mercapto-1-propane sulfonate, sodium polydisulfide propane sulfonate, sodium 3-(benzothiazole-2-mercapto)-propane sulfonate, isothiourea propanesulfonic acid inner salt, sodium allyl sulfonate, benzotriazole, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, and common amino acids such as glycine, tryptophan, and aspartic acid.

[0059] b. Prepare a salt solution II of a certain concentration; the salt solution II is one or a combination of sodium chloride, potassium chloride, potassium bromide, sodium bromide, potassium iodide, sodium iodide, potassium perchlorate, potassium sulfate, copper chloride, copper sulfate, sodium carbonate, ammonium nitrate, ammonium bicarbonate, ferric chloride, potassium hydroxide, sodium hydroxide, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, phosphoric acid, formic acid, oxalic acid, and chloroacetic acid; the concentration of the salt solution II is 0.01 mol / L to 1 mol / L.

[0060] c. Mix solution I and salt solution II in a certain proportion to prepare solution III for microporous aluminum foil in the next step, and the pH range of the mixed solution III is less than 4.5 or greater than 8.5. After mixing, the concentration of the water-soluble additive in the solution is 1-500 ppm.

[0061] d. Immerse the original aluminum foil IV in solution III and put solution III in a convection state by blowing air or stirring.

[0062] e. The reaction time is 10 s to 60 min. The aluminum foil IV is taken out, cleaned and dried to obtain a microporous aluminum foil V.

[0063] Examples

[0064]

[0065]

[0066] When the aluminum foil is immersed in solution III, the additive molecules can be adsorbed on the surface of the aluminum foil. The water-soluble additive solution I contains macromolecules and small molecules with amino, hydroxyl, thiol, carboxyl, ether bond, aldehyde, and nitrogen-containing functional groups. Macromolecules refer to molecules with a molecular weight greater than 1000, and small molecules refer to molecules with a molecular weight below 1000. Additives with larger molecular weights are uniformly adsorbed on the surface of aluminum by virtue of functional groups such as hydroxyl, amino, carboxyl, and thiol. Additives with smaller molecular weights can supplement the adsorption of macromolecules on the surface space of the aluminum foil, thereby achieving coverage of the surface of the aluminum foil. During the reaction, the ions in solution III react with the aluminum surface. Al and the Al2O3 on the surface are amphoteric substances that can react with acids and bases. Al is a reducing metal that can react with oxidizing ions, such as Cu 2+ 、Ag + , Fe 3+ wait.

[0067] Reaction with acids:

[0068] Aluminum reacts with strong acids (such as hydrochloric acid, sulfuric acid, etc.) to generate aluminum ions and hydrogen:

[0069] Al(s)+3HCl(aq)→AlCl3(aq)+3 / 2H2(g),

[0070] 2Al(s)+3H2SO4(aq)→Al2(SO4)3(aq)+3H2(g);

[0071] Reaction with base:

[0072] Aluminum reacts with a strong base (such as sodium hydroxide) to produce aluminates and hydrogen:

[0073] 2Al(s)+2NaOH(aq)+6H2O(l)→2NaAl(OH)4+3H2(g);

[0074] Reaction of oxide Al2O3 with acid and alkali:

[0075] Alumina (Al2O3) reacts with strong acid to generate aluminum ions:

[0076] Al2O3(s)+6HCl(aq)→2AlCl3(aq)+3H2O(l);

[0077] Alumina reacts with strong base to form aluminate:

[0078] Al2O3(s)+2NaOH(aq)+3H2O(l)→2NaAl(OH)4;

[0079] The additive coverage on a small part of the aluminum foil surface is destroyed, resulting in holes. The concentration of ions that react with Al in the solution is related to the degree of damage to the additive coverage. When the total concentration of ions that can react with Al in the solution is 0.01mol / L-5mol / L, 0.2%-15% of the additive coverage is destroyed.

[0080] Copper ion (Cu2+):

[0081] When aluminum metal is immersed in a solution containing copper ions, the following reaction occurs:

[0082] Al(s)+Cu2+(aq)→Al 3+ (aq)+Cu(s);

[0083] This reaction is a redox reaction, aluminum is oxidized, and copper ions are reduced to metallic copper precipitates.

[0084] Silver ion (Ag+):

[0085] A similar redox reaction occurs when aluminum metal is immersed in a solution containing silver ions:

[0086] 2Al(s)+3Ag+(aq)→2Al 3+ (aq)+3Ag(s);

[0087] Aluminum is oxidized and silver ions are reduced to metallic silver precipitates.

[0088] Iron ion (Fe3+):

[0089] In acidic solution, aluminum can also react with trivalent iron ions (Fe3+):

[0090] 2Al(s)+6H + (aq)+2Fe 3+ (aq)→2Al 3+ (aq)+2Fe 2+ (aq)+3H2(g);

[0091] The reaction produces ferrous ions and hydrogen gas.

[0092] When the solution contains Cl - 、F - When there are anions, due to the small radius and high penetration of these ions, it is easy to destroy the oxide film and produce corrosion holes. By controlling the type, molecular weight, concentration of additives, as well as the composition, concentration, pH, temperature, reaction time, and solution convection speed of the salt solution, microporous aluminum foil with different pore sizes and pore structures can be obtained. The pore size is inversely proportional to the molecular weight and concentration of the additive. The larger the molecular weight and the higher the concentration, the smaller the pore size; the pore depth is proportional to the concentration of ions in the solution, the temperature, the reaction time, and the solution convection speed. The greater the ion concentration, the higher the temperature, the reaction time, and the greater the solution convection speed, the deeper the pore depth; the pore density is inversely proportional to the additive concentration and proportional to the salt ion concentration. The smaller the additive concentration and the higher the salt ion concentration, the greater the pore density; Al is an amphoteric metal. In the range of pH <4.5 and pH >8.5, the higher the H+ or OH- concentration, the faster the reaction rate.

[0093] This aluminum foil with a microporous structure and its preparation method have multiple advantages over the existing technology:

[0094] Simple operation: The preparation process is simple and can be completed by simply preparing the solution and allowing it to flow. No complicated operating steps or equipment are required.

[0095] Environmentally friendly: The solution has simple ingredients and does not contain substances harmful to the environment. It meets environmental protection requirements and is conducive to sustainable production.

[0096] Controllable pore structure: pore diameter, pore depth and pore density can be precisely controlled, pore diameter is 0.4-50um, pore density is 2000-20000 / cm2, pore depth is 1-10um. Different micropore structures can be customized according to specific needs.

[0097] Achieve mass production: After simple test verification, large-scale mass production can be achieved to ensure product stability and reliability.

[0098] Excellent product quality: Please refer to the instructions attached Figure 2 In the scanning electron microscope image, the edge of the hole is smooth, there are no obvious particles or protrusions, and there is no burr or oxidation on the surface; compared with traditional microporous aluminum foil, this product does not have quality problems such as burrs and oxidation, which improves the overall quality and reliability of the product.

[0099] High production efficiency: The preparation process is simple and efficient, the production efficiency is high, it can meet the needs of large-scale production and reduce production costs.

[0100]

[0101] In summary, this new type of microporous aluminum foil and its preparation method not only have significant technological innovations, but also have multiple advantages such as simple operation, environmental friendliness, controllable pore structure, efficient mass production and excellent product quality. It is expected to be widely used and promoted in the fields of microelectronics, new energy, etc.

[0102] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. An aluminum foil with a microporous structure, characterized in that: The aluminum foil is a rolled aluminum foil, the micropores have a pore size of 0-150 μm, and the micropores include blind holes and through holes.

2. The aluminum foil according to claim 1, characterized in that: The pore size is 0.4-50um, and the pore density is 2000-20000 / cm 2 , the hole depth is 1-10um.

3. A method for preparing an aluminum foil having a microporous structure, characterized in that: The specific steps are as follows: a. Prepare a water-soluble additive solution I, wherein the water-soluble additive is one or more of hydrolyzed protein peptide, sodium carboxymethyl cellulose, polyvinyl pyrrolidone, cellulose acetate, cellulose ether, starch, polyvinyl alcohol, polyethylene glycol, polypropylene glycol, gelatin, carboxymethyl chitosan, polyacrylamide, polyacrylic acid, xanthan gum, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate), polymerized vinyl sulfonic acid, polyacrylamide, polyaniline, sodium 3-mercapto-1-propane sulfonate, sodium polydisulfide propane sulfonate, sodium 3-(benzothiazole-2-mercapto)-propane sulfonate, isothiourea propanesulfonic acid inner salt, sodium allyl sulfonate, benzotriazole, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, and common amino acids such as glycine, tryptophan, and aspartic acid; b. Prepare a salt solution II of a certain concentration; the salt solution II is one or more of sodium chloride, potassium chloride, potassium bromide, sodium bromide, potassium iodide, sodium iodide, potassium perchlorate, potassium sulfate, copper chloride, copper sulfate, sodium carbonate, ammonium nitrate, ammonium bicarbonate, ferric chloride, potassium hydroxide, sodium hydroxide, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, phosphoric acid, formic acid, oxalic acid, and chloroacetic acid; c. Mixing solution I and salt solution II in a certain proportion to form solution III for preparing microporous aluminum foil in the next step, wherein the concentration of the water-soluble additive in the solution is 1-500 ppm after mixing; d. Immerse the original aluminum foil IV in the solution III, and use air blowing or stirring to make the solution III in a convection state; e. After a specific reaction time, the aluminum foil IV is taken out, cleaned and dried to obtain a microporous aluminum foil V.

4. The method for preparing the aluminum foil with a microporous structure according to claim 3, characterized in that: The water-soluble additive solution I contains macromolecules and small molecules with amino, hydroxyl, thiol, carboxyl, ether bond, aldehyde, and nitrogen-containing functional groups. Macromolecules refer to molecules with a molecular weight greater than 1000, and small molecules refer to molecules with a molecular weight less than 1000.

5. The method for preparing the aluminum foil with a microporous structure according to claim 3, characterized in that: A water-soluble additive solution I is prepared, and the solution may be heated or stirred at room temperature according to the solubility of the additive molecules.

6. The method for preparing the aluminum foil with a microporous structure according to claim 3, characterized in that: The concentration of salt solution II is 0.01 mol / L to 1 mol / L.

7. The method for preparing the aluminum foil with a microporous structure according to claim 3, characterized in that: The pH range of the solution III is less than 4.5, or greater than 8.

5.

8. The method for preparing the aluminum foil with a microporous structure according to claim 3, characterized in that: In step e, the specific reaction time is 10s to 60min.

9. The method for preparing an aluminum foil having a microporous structure according to claim 3, characterized in that: The additive solution I in step a can also be first coated on the surface of the aluminum foil to form a film, and then the aluminum foil after the film is immersed in the salt solution II to perform steps d and e.

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