Multilayer aluminum current collector and preparation method thereof

Abstract

The invention relates to the technical field of current collectors, and particularly discloses a multi-layer aluminum current collector and a preparation method thereof.Hollow porous polymer microspheres are prepared into slurry to be coated on the surface of a polymer base film of the current collector, so that the surface energy of the base film and the adhesive force between the base film and an aluminum oxide layer are improved, and the weight of the current collector is further reduced; the energy density is improved. In addition, the brittleness of the aluminum oxide layer is reduced by the molten polymer microspheres, the ductility of the aluminum oxide layer is improved, and the problem that the sheet layer binding force is reduced due to the fact that the ductility difference between the current collector and the base film and the aluminum layer is large in the follow-up pole piece processing engineering is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of current collectors, and specifically to a multi-layer aluminum current collector and a preparation method thereof. Background Art

[0002] In the field of battery manufacturing, the current collector is an important part of the battery, and its performance directly affects the energy density, cycle life and safety of the battery. Traditional current collectors are mostly made of a single material, such as pure aluminum or pure copper. These materials are prone to structural damage due to expansion and contraction during the charge and discharge process of the battery, affecting the battery performance. Therefore, developing a new type of high-performance current collector to improve its mechanical properties and electrochemical properties has become a research hotspot.

[0003] In the prior art, due to the low bonding force between aluminum and the polymer-based film, it cannot meet the application requirements. Therefore, an alumina layer is usually provided between the base film and the aluminum layer to improve the bonding strength. However, since the alumina layer is a ceramic material with strong brittleness and low elongation rate, in the subsequent application of the current collector, due to the large difference in elongation rate between the alumina layer and the base film, a large stress difference exists between the two, so that delamination is still likely to occur under external force, and the bonding force decreases. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-layer aluminum current collector and a preparation method thereof. By applying hollow porous polymer microspheres, the structural characteristics of the alumina layer in the multi-layer aluminum current collector are optimized, and the surface energy, adhesion and ductility of the current collector are improved, thereby improving the overall performance of the battery.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A preparation method of a multi-layer aluminum current collector, specifically:

[0007] Step 1: Add hollow porous polymer microspheres into a solvent, stir evenly to obtain a slurry, and coat the slurry on the surface of a polymer-based film to obtain a first base film;

[0008] Step 2: Magnetron sputter an alumina layer on the surface of the first base film, and the thickness of the alumina layer is 0.1 - 1 μm to obtain a second base film;

[0009] Step 3: Evaporate an aluminum layer on the surface of the second base film to obtain a multi-layer aluminum current collector.

[0010] As a limitation of the present invention, the particle size of the hollow porous polymer microspheres is 100 - 300 nm, and the porosity is 30% - 60%; the polymer-based film is a polyethylene terephthalate-based film.

[0011] As a limitation of the present invention, the preparation method of the hollow porous polymer microspheres is:

[0012] Dissolve the synthetic polymer in an organic solvent, add a pore-forming agent to obtain Solution A, mix Solution A with an organic alcohol, and mechanically homogenize to obtain a mixed solution as the dispersed phase O;

[0013] Dissolve the surfactant in deionized water to obtain a solution as the continuous phase W. Pass the continuous phase W and the dispersed phase O through a self-assembled two-phase microscale channel respectively, shear to obtain an oil-in-water emulsion, wash after horizontal rotation curing, and freeze-dry to obtain hollow porous polymer microspheres.

[0014] As a limitation of the present invention, the synthetic polymer is one or a mixture of polypropylene, polylactic acid, polyethylene terephthalate-1,4-cyclohexanedimethanol ester, and polyethylene terephthalate-1,4-cyclohexanedimethanol glycol ester; the solvent is one or a mixture of acetone, dichloromethane, and chloroform; the pore-forming agent is one or a mixture of dodecane, tridecane, and petroleum ether; the organic alcohol is one or a mixture of methanol, ethanol, and propanol.

[0015] As a limitation of the present invention, the inner channel diameter of the two-phase microscale channel is 300 nm to 1 μm, and the outer channel diameter of the two-phase microscale channel is 500 nm to 10 μm.

[0016] As a limitation of the present invention, the dispersed phase O is located in the inner channel of the two-phase microscale channel, and the flow rate is 0.1 to 2 mL / h; the continuous phase W is located in the outer channel of the two-phase microscale channel, and the flow rate is 0.5 to 5 mL / h.

[0017] As a limitation of the present invention, in Step 1, the slurry contains a polyurethane adhesive, and the preparation method of the polyurethane adhesive is as follows:

[0018] Under nitrogen as a protective gas, mix isophthalic acid, adipic acid, neopentyl glycol, and ethylene glycol, add tetrabutyl titanate, stir evenly and then heat to 200 - 210 °C for reaction for 2 - 4 h, and then react at 240 - 250 °C and -80 to -100 KPa for 3 - 5 h to obtain a polyester polyol;

[0019] Add the polyester polyol to ethyl acetate to obtain a polyester polyol solution, add isocyanate to the polyester polyol solution, stir well, and then let it stand at room temperature for 20 - 30 min to obtain the polyurethane adhesive.

[0020] As a limitation of the present invention, the molar ratio of isophthalic acid, adipic acid, neopentyl glycol, and ethylene glycol is (0.9 - 1.2):1.0:(1.7 - 1.9):(0.7 - 0.8), and the mass ratio of the polyester polyol to the isocyanate is 1:(0.04 - 0.08).

[0021] A multi-layer aluminum current collector is made by using the preparation method of any one of the above.

[0022] As a limitation of the present invention, the application of the multi-layer aluminum current collector in a battery.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] In the present invention, a pore-forming agent is dispersed in a polymer emulsion to prepare hollow porous polymer microspheres. After being coated on the surface of the base film, it can improve the surface energy of the base film, enhance the adhesion between the base film and the alumina layer, and further reduce the weight of the current collector and improve the energy density. In addition, a polyurethane adhesive is added to the slurry to further enhance the adhesion between the base film and the alumina layer, enhance the peel strength of the current collector, and avoid a rapid decrease in the peel strength after roll pressing.

[0025] During aluminum evaporation, the hollow porous polymer microspheres melt to form a porous alumina layer. The molten polymer adheres to the pore walls of the porous alumina, improving the ductility of the alumina layer and reducing the problem of a decrease in the layer bonding force due to the large difference in ductility between the base film and the aluminum layer during subsequent electrode sheet processing of the current collector. In addition, the molten polymer adhering to the pore walls of the porous alumina can reduce the brittleness of the alumina layer and avoid the problem of abnormal power-off of the current collector caused by the fracture of the alumina layer due to charging and discharging expansion during normal use of the battery. Specific Embodiments

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] The PET base film (thickness: 6 μm) is provided by Toray Korea, polyethylene terephthalate-1,4-cyclohexanedimethanol ester (grade: TX1001, molecular weight: 12000) is provided by Eastman Chemical, polypropylene (grade: 951-000, molecular weight: 80000) is provided by Sinopec, polyvinyl alcohol (PVA-1788, molecular weight: 100000) is provided by Jinan Yuyi, and the surfactant PEG-400 (hydroxyl value: 255-312 mgKOH / g) is provided by Hai'an Petroleum in Jiangsu Province.

[0028] Example 1: A preparation method of a multi-layer aluminum current collector, specifically as follows:

[0029] Step 1: Add hollow porous polymer microspheres into an ethanol solution with a mass fraction of 60%, stir evenly to obtain a slurry with a solid content of 25%, and coat the slurry on the surface of a 6-μm-thick PET base film to obtain a first base film;

[0030] Step 2: Set the arrangement mode of the target materials as 24 alumina target materials (with a purity of 99.9% each), the magnetron sputtering power density as 50 W / cm 2 , the vacuum degree as 0.1 Pa, the protective gas as argon, the argon flow rate as 50 L / min, the deposition time as 10 s, and magnetron sputter a 0.4-μm-thick alumina layer on the surface of the first base film to obtain a second base film;

[0031] Step 3: Conduct evaporation coating on the surface of the second base film. Select pure aluminum wire (purity: 99%), when the vacuum in the evaporation chamber reaches a vacuum degree of 5×10 -3 Pa, the wire feeding speed is 300 mm / min, introduce argon to protect and control the vacuum degree at 5×10 -2 Pa, the temperature of the base film cooling roller is -20°C, the tape running speed is 20 m / min, and form an aluminum layer with a single-layer thickness of 2 μm to obtain a multi-layer aluminum current collector with the PET base film, porous alumina layer, and aluminum layer in sequence from the inside to the outside in the thickness direction.

[0032] Among them, the preparation method of the hollow porous polymer microspheres is as follows:

[0033] Dissolve polyethylene terephthalate-1,4-cyclohexanedimethanol ester in dichloromethane, add dodecane as a pore-forming agent, stir evenly to obtain solution A containing 2% v / v dodecane. In solution A, there is also 2 wt% of polyethylene terephthalate-1,4-cyclohexanedimethanol ester. After mixing solution A and methanol at a mass ratio of 1:1 and mechanically homogenizing, obtain the dispersed phase O;

[0034] Dissolve the surfactant PEG-400 in deionized water to obtain a surfactant solution with a mass concentration of 1%. Use the surfactant solution as the continuous phase W. Let the continuous phase W and the dispersed phase O pass through a self-assembled two-phase micro-scale channel respectively. The dispersed phase O is located in the inner channel of the two-phase micro-scale channel, the inner channel diameter is 100 nm, the flow rate of the dispersed phase O is 1 mL / h, the continuous phase W is located in the outer channel of the two-phase micro-scale channel, the outer channel diameter is 300 nm, and the flow rate of the continuous phase W is 2 mL / h;

[0035] Use a 0.5 wt% polyvinyl alcohol solution as the collecting liquid c, shear to obtain an oil-in-water emulsion, then cure by horizontally rotating at 60 rpm for 36 h, wash after curing, and freeze-dry to obtain hollow porous polymer microspheres with a particle size of 150 nm and a porosity of 50%.

[0036] Example 2: A preparation method of a multi-layer aluminum current collector, specifically as follows:

[0037] Step 1: Add hollow porous polymer microspheres into an ethanol solution with a mass fraction of 60%, stir evenly to obtain a slurry with a solid content of 25%, and coat the slurry on the surface of a 6-μm-thick PET base film to obtain a first base film;

[0038] Step 2: Set the target arrangement as 24 alumina targets (with a purity of 99.9% each), the magnetron sputtering power density is 50 W / cm 2 , the vacuum degree is 0.1 Pa, the protective gas is argon, the argon flow rate is 50 L / min, the deposition time is 10 s, magnetron sputter a 0.4-μm-thick alumina layer on the surface of the first base film to obtain a second base film;

[0039] Step 3: Perform evaporation coating on the surface of the second base film. Select pure aluminum wire (purity: 99%), when the vacuum in the evaporation chamber reaches a vacuum degree of 5×10 -3 Pa, the wire feeding speed is 300 mm / min, introduce argon to protect and control the vacuum degree at 5×10 -2 Pa, the temperature of the base film cooling roller is -20°C, the tape running speed is 20 m / min, form an aluminum layer with a single layer thickness of 2 μm, and obtain a multi-layer aluminum current collector with a PET base film, a porous alumina layer, and an aluminum layer from the inside to the outside in the thickness direction.

[0040] Among them, the preparation method of the hollow porous polymer microspheres is as follows:

[0041] Dissolve polyethylene terephthalate-1,4-cyclohexanedimethanol ester in dichloromethane, add dodecane as a pore-forming agent, stir evenly to obtain solution A containing 4% v / v dodecane. In solution A, solution A also contains 2 wt% of polyethylene terephthalate-1,4-cyclohexanedimethanol ester. Mechanically homogenize solution A with methanol to obtain a dispersed phase O;

[0042] Dissolve the surfactant PEG-400 in deionized water to obtain a surfactant solution with a mass concentration of 1%. Use the surfactant solution as the continuous phase W. Let the continuous phase W and the dispersed phase O pass through a self-assembled two-phase micro-scale channel respectively. The dispersed phase O is located in the inner channel of the two-phase micro-scale channel, the inner channel diameter is 100 nm, the flow rate of the dispersed phase O is 1 mL / h, the continuous phase W is located in the outer channel of the two-phase micro-scale channel, the outer channel diameter is 300 nm, and the flow rate of the continuous phase W is 2 mL / h;

[0043] Use a 0.5 wt% polyvinyl alcohol solution as the collecting liquid c, shear to obtain an oil-in-water emulsion, then rotate horizontally at 60 rpm for 36 h to cure, wash after curing, and freeze-dry to obtain hollow porous polymer microspheres with a particle size of 150 nm and a porosity of 60%.

[0044] Example 3: A method for preparing a multi-layer aluminum current collector, specifically as follows:

[0045] Step 1: Add hollow porous polymer microspheres into an ethanol solution with a mass fraction of 60%, stir evenly to obtain a slurry with a solid content of 25%, and coat the slurry on the surface of a 6-μm-thick PET base film to obtain a first base film;

[0046] Step 2: Set the target arrangement to 24 alumina targets (with a purity of 99.9% each), the magnetron sputtering power density to 50 W / cm 2 , the vacuum degree to 0.1 Pa, the protective gas to argon, the argon flow rate to 50 L / min, the deposition time to 12 s, and magnetron sputter a 0.5-μm-thick alumina layer on the surface of the first base film to obtain a second base film;

[0047] Step 3: Perform evaporation coating on the surface of the second base film. Select pure aluminum wire (purity: 99%), when the vacuum in the evaporation chamber reaches a vacuum degree of 5×10 -3 Pa, the wire feeding speed is 300 mm / min, introduce argon to control the vacuum degree at 5×10 -2 Pa, the temperature of the base film cooling roller is -20°C, and the tape running speed is 20 m / min to form an aluminum layer with a single layer thickness of 2 μm, obtaining a multi-layer aluminum current collector with a thickness direction from the inside out being a PET base film, a porous alumina layer, and an aluminum layer.

[0048] Among them, the method for preparing the hollow porous polymer microspheres is as follows:

[0049] Dissolve polyethylene terephthalate-1,4-cyclohexanedimethanol ester in dichloromethane, add dodecane as a pore-forming agent, stir evenly to obtain solution A containing 2% v / v dodecane. In solution A, solution A also contains 2 wt% of polyethylene terephthalate-1,4-cyclohexanedimethanol ester. Mechanically homogenize solution A with methanol to obtain a dispersed phase O;

[0050] Dissolve the surfactant PEG-400 in deionized water to obtain a surfactant solution with a mass concentration of 1%. Use the surfactant solution as the continuous phase W. Let the continuous phase W and the dispersed phase O pass through a self-assembled two-phase micro-scale channel respectively. The dispersed phase O is located in the inner channel of the two-phase micro-scale channel, the inner channel diameter is 200 nm, the flow rate of the dispersed phase O is 1.5 mL / h, the continuous phase W is located in the outer channel of the two-phase micro-scale channel, the outer channel diameter is 400 nm, and the flow rate of the continuous phase W is 3 mL / h;

[0051] Using a 0.5 wt% polyvinyl alcohol solution as the collection liquid c, an oil-in-water emulsion was obtained after shearing, and then cured by horizontal rotation at 60 rpm for 36 h. After curing, it was washed and freeze-dried to obtain hollow porous polymer microspheres with a particle size of 280 nm and a porosity of 40%.

[0052] Example 4: A method for preparing a multi-layer aluminum current collector, specifically as follows:

[0053] Step 1: Add the hollow porous polymer microspheres into an ethanol solution with a mass fraction of 60%, stir evenly to obtain a slurry with a solid content of 25%, and coat the slurry on the surface of a 6-μm-thick PET base film to obtain a first base film;

[0054] Step 2: Set the target arrangement to 24 alumina targets (with a purity of 99.9% each), the magnetron sputtering power density to 50 W / cm 2 , the vacuum degree to 0.1 Pa, the protective gas to argon, the argon flow rate to 50 L / min, the deposition time to 10 s, and magnetron sputter a 0.4-μm-thick alumina layer on the surface of the first base film to obtain a second base film;

[0055] Step 3: Perform evaporation coating on the surface of the second base film. Select pure aluminum wire (purity: 99%), when the vacuum in the evaporation chamber reaches a vacuum degree of 5×10 -3 Pa, the wire feeding speed is 300 mm / min, argon is introduced to control the vacuum degree at 5×10 -2 Pa, the temperature of the base film cooling roller is -20°C, and the tape running speed is 20 m / min to form an aluminum layer with a single layer thickness of 2 μm, obtaining a multi-layer aluminum current collector with a PET base film, a porous alumina layer, and an aluminum layer from the inside to the outside in the thickness direction.

[0056] Among them, the preparation method of the hollow porous polymer microspheres is as follows:

[0057] Dissolve polypropylene in chloroform, add tridecane as a pore-forming agent, stir evenly to obtain solution A containing 2% v / v tridecane. In solution A, there is also 2 wt% of polypropylene. Mechanically homogenize solution A with methanol to obtain the dispersed phase O;

[0058] Dissolve the surfactant PEG-400 in deionized water to obtain a surfactant solution with a mass concentration of 1%. Using the surfactant solution as the continuous phase W, let the continuous phase W and the dispersed phase O pass through a self-assembled two-phase micro-scale channel respectively. The dispersed phase O is located in the inner channel of the two-phase micro-scale channel, the inner channel diameter is 100 nm, the flow rate of the dispersed phase O is 1 mL / h, the continuous phase W is located in the outer channel of the two-phase micro-scale channel, the outer channel diameter is 300 nm, and the flow rate of the continuous phase W is 2 mL / h;

[0059] Using a 0.5 wt% polyvinyl alcohol solution as the collecting liquid c, an oil-in-water emulsion was obtained after shearing, and then cured by horizontal rotation at 60 rpm for 36 h. After curing, it was washed and freeze-dried to obtain hollow porous polymer microspheres.

[0060] Example 5: A method for preparing a multi-layer aluminum current collector, specifically:

[0061] Step 1: Add the hollow porous polymer microspheres into an ethanol solution with a mass fraction of 60%, stir evenly to obtain a slurry with a solid content of 25%. Add 18% of the polyurethane adhesive based on the mass of the slurry to the slurry, stir evenly, and coat it on the surface of a 6-μm-thick PET base film to obtain the first base film.

[0062] Step 2: Set the target arrangement to 24 alumina targets (all with a purity of 99.9%), the magnetron sputtering power density to 50 W / cm 2 , the vacuum degree to 0.1 Pa, the protective gas to argon, the argon flow rate to 50 L / min, the deposition time to 10 s, and magnetron sputter a 0.4-μm-thick alumina layer on the surface of the first base film to obtain the second base film.

[0063] Step 3: Perform evaporation coating on the surface of the second base film. Select pure aluminum wire (purity: 99%). When the vacuum in the evaporation coating chamber reaches a vacuum degree of 5×10 -3 Pa, the wire feeding speed is 300 mm / min, argon is introduced to control the vacuum degree at 5×10 -2 Pa, the temperature of the base film cooling roller is -20°C, and the tape running speed is 20 m / min to form an aluminum layer with a single layer thickness of 2 μm, obtaining a multi-layer aluminum current collector with the PET base film, porous alumina layer, and aluminum layer from the inside to the outside in the thickness direction.

[0064] Among them, the preparation method of the hollow porous polymer microspheres is:

[0065] Dissolve polyethylene terephthalate-1,4-cyclohexanedimethanol ester in dichloromethane, add dodecane as a pore-forming agent, stir evenly to obtain solution A containing 2% v / v dodecane. In solution A, solution A also contains 2 wt% of polyethylene terephthalate-1,4-cyclohexanedimethanol ester. Mechanically homogenize solution A with methanol to obtain the dispersed phase O.

[0066] Dissolve the surfactant PEG-400 in deionized water to obtain a surfactant solution with a mass concentration of 1%. Using the surfactant solution as the continuous phase W, let the continuous phase W and the dispersed phase O pass through a self-assembled two-phase micro-scale channel respectively. The dispersed phase O is located in the inner channel of the two-phase micro-scale channel, the diameter of the inner channel is 100 nm, the flow rate of the dispersed phase O is 1 mL / h, the continuous phase W is located in the outer channel of the two-phase micro-scale channel, the diameter of the outer channel is 300 nm, and the flow rate of the continuous phase W is 2 mL / h;

[0067] Using a 0.5 wt% polyvinyl alcohol solution as the collecting liquid c, shear to obtain an oil-in-water emulsion, then cure it by horizontal rotation at 60 rpm for 36 h, wash after curing, and freeze-dry to obtain hollow porous polymer microspheres with a particle size of 150 nm and a porosity of 50%.

[0068] The preparation method of the polyurethane adhesive is as follows:

[0069] Under nitrogen as the protective gas, mix isophthalic acid, adipic acid, neopentyl glycol, and ethylene glycol in a molar ratio of 1.1:1.0:1.8:0.75, add 0.2% of tetrabutyl titanate based on the total mass of the mixture, stir evenly and then heat up to 210 °C and react for 3 h, and then react at 250 °C and -100 KPa for 4 h to obtain a polyester polyol;

[0070] Add 4 g of the polyester polyol to 6 g of ethyl acetate to obtain a polyester polyol solution. Add 0.2 g of isocyanate to the polyester polyol solution, stir well, and let it stand at room temperature for 30 min to obtain the polyurethane adhesive.

[0071] Next, control experiments are carried out, specifically Comparative Example 1 and Comparative Example 2, as described below:

[0072] Comparative Example 1: This comparative example relates to a preparation method of a multi-layer aluminum current collector. The difference from Example 1 is that the base film is not coated with a slurry containing hollow porous polymer microspheres. Specifically:

[0073] Step 1: Set the target arrangement to 24 alumina targets (purity is 99.9% for all), the magnetron sputtering power density is 50 W / cm 2 , the vacuum degree is 0.1 Pa, the protective gas is argon, the argon flow rate is 50 L / min, the deposition time is 10 s, and magnetron sputter a 0.4-μm-thick alumina layer on the surface of a 6-μm-thick PET base film to obtain a second base film;

[0074] Step 2: Conduct evaporation coating on the surface of the second base film. Select pure aluminum wire (purity: 99%), when the vacuum in the evaporation coating chamber reaches a vacuum degree of 5×10 -3 Pa, the wire feeding speed is 300 mm / min, and introduce argon to protect the vacuum degree and control it at 5×10 -2At a base film cooling roll temperature of -20°C and a web running speed of 20 m / min, an aluminum layer with a single-layer thickness of 2 μm was formed to obtain a multi-layer aluminum current collector with a thickness direction from the inside out being a PET base film, a porous alumina layer, and an aluminum layer.

[0075] Comparative Example 2: This comparative example relates to a method for preparing a multi-layer aluminum current collector, which is different from Example 1 in that PETG particles with a particle size of 150 nm are directly selected and coated on the surface of the base film. Specifically:

[0076] Step 1: PETG particles with a particle size of 150 nm were added to an ethanol solution with a mass fraction of 60%, stirred evenly to obtain a slurry with a solid content of 25%, and the slurry was coated on the surface of a 6-μm-thick PET base film to obtain a first base film.

[0077] Step 2: The target arrangement was set to 24 alumina targets (all with a purity of 99.9%), the magnetron sputtering power density was 50 W / cm 2 , the vacuum degree was 0.1 Pa, the protective gas was argon, the argon flow rate was 50 L / min, the deposition time was 10 s, and a 0.4-μm-thick alumina layer was magnetron sputtered on the surface of the first base film to obtain a second base film.

[0078] Step 3: Evaporation coating was carried out on the surface of the second base film. Pure aluminum wire (purity: 99%) was selected. When the vacuum in the evaporation chamber reached a vacuum degree of 5×10 -3 Pa, the wire feeding speed was 300 mm / min, and argon was introduced to control the vacuum degree at 5×10 -2 Pa, the base film cooling roll temperature was -20°C, the web running speed was 20 m / min, and an aluminum layer with a single-layer thickness of 2 μm was formed to obtain a multi-layer aluminum current collector with a thickness direction from the inside out being a PET base film, a porous alumina layer, and an aluminum layer.

[0079] Detection experiment: Multi-layer aluminum current collectors were prepared according to the preparation methods in each example and comparative ratio as samples for the following tests.

[0080] Initial peel force test: The multi-layer aluminum current collector sample was cut into test specimens of 15 mm × 100 mm. A 3M-9080A-15-mm tape was pasted on a stainless steel plate, and then the aluminum side of the test sample was evenly pasted on the double-sided tape. A 2-kg standard small pressure roller was used to squeeze back and forth twice. Then, a 3M-9080A-14-mm tape was pasted on the surface of the test sample, and a 2-kg standard small pressure roller was used to squeeze back and forth twice. Subsequently, the pressed sample was placed on a tensile machine, stretched at 180°, the stretching speed was 100 mm / min, and the width was set to 14 mm to test the initial peel force of the test sample, and the maximum value was taken as the result.

[0081] Peeling force test after rolling: During the process of preparing the positive electrode sheet, the multi-layer aluminum current collector needs to undergo a rolling process. In order to test the change in the peeling force of the current collector after rolling, a rolling peeling force test is carried out. The diameter of the test roll is 1500 mm, the rolling pressure is 500 KN, the maximum width is 1000 mm, and the roll gap is 10 μm. The multi-layer aluminum current collector is rolled; after rolling, it is cut into test specimens of 15 mm × 100 mm in size. The 3M-9080A-15 mm tape is pasted on the stainless steel plate, and then the aluminum side of the test sample is evenly pasted on the double-sided tape. A 2 Kg standard small pressure roller is used to squeeze back and forth twice. Then, the 3M-9080A-14 mm tape is pasted on the surface of the test sample, and a 2 Kg standard small pressure roller is used to squeeze back and forth twice. Subsequently, the pressed sample is placed on a tensile machine and stretched at 180°, the stretching speed is 100 mm / min, the width is set to 14 mm, and the initial peeling force of the test sample is measured, and the maximum value is taken as the result.

[0082] Initial peeling force (N / m) Peeling force after rolling (N / m) Example 1 1583 1302 Example 2 1562 1299 Example 3 1513 1274 Example 4 1608 1355 Example 5 1617 1376 Comparative Example 1 1369 639 Comparative Example 2 1492 871

[0083] Conclusion: It can be seen from the test data that the initial peeling force and the peeling force after rolling of the multi-layer aluminum current collectors prepared in Comparative Example 1 and Comparative Example 2 are lower than those of the multi-layer aluminum current collector prepared in Example 1. The multi-layer aluminum current collector provided by the present invention has good peel resistance. By applying hollow porous polymer microspheres, the present invention optimizes the structural characteristics of the alumina layer in the multi-layer aluminum current collector, improves the surface energy, adhesion and ductility of the current collector, thereby improving the overall performance of the battery.

[0084] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A preparation method of a multi-layer aluminum current collector, characterized in that: Specifically: Step 1: adding the hollow porous polymer microspheres to a solvent, stirring evenly to obtain a slurry, and coating the slurry on the surface of a polymer base film to obtain a first base film; Step 2: magnetron sputtering an aluminum oxide layer on the surface of the first base film, with a thickness of 0.1 to 1 μm, to obtain a second base film; Step 3: Evaporate an aluminum layer on the surface of the second base film to obtain a multi-layer aluminum current collector.

2. The preparation method of a multi-layer aluminum current collector according to claim 1, characterized in that: The particle size of the hollow porous polymer microspheres is 100-300nm, and the porosity is 30%-60%. The high molecular polymer base film is a polyethylene terephthalate base film.

3. The preparation method of a multi-layer aluminum current collector according to claim 1, characterized in that: The preparation method of hollow porous polymer microspheres is as follows: Dissolving a synthetic polymer in an organic solvent, adding a porogen to obtain a solution A, mixing the solution A with an organic alcohol, and mechanically homogenizing to obtain a mixed solution as a dispersed phase O; The surfactant is dissolved in deionized water to obtain a solution as a continuous phase W. The continuous phase W and the dispersed phase O are respectively passed through self-assembled two-phase micrometer-scale channels. After shearing, an oil-in-water emulsion is obtained. After horizontal rotation solidification, it is washed and freeze-dried to obtain hollow porous polymer microspheres.

4. The preparation method of a multi-layer aluminum current collector according to claim 3, characterized in that: The synthetic high molecular polymer is a mixture of one or more of polypropylene, polylactic acid, polyethylene terephthalate-1,4-cyclohexanedimethanol, and polyethylene terephthalate-1,4-cyclohexanedimethanol; the solvent is a mixture of one or more of acetone, dichloromethane, and chloroform; the porogen is a mixture of one or more of dodecane, tridecane, and petroleum ether; and the organic alcohol is a mixture of one or more of methanol, ethanol, and propanol.

5. The preparation method of a multi-layer aluminum current collector according to claim 3, characterized in that: The inner channel diameter of the two-phase micrometer-scale channel is 300nm-1μm, and the outer channel diameter of the two-phase micrometer-scale channel is 500nm-10μm.

6. The preparation method of a multi-layer aluminum current collector according to claim 3, characterized in that: The dispersed phase O is located in the inner channel of the two-phase micrometer-scale channel with a flow rate of 0.1 to 2 mL / h; the continuous phase W is located in the outer channel of the two-phase micrometer-scale channel with a flow rate of 0.5 to 5 mL / h.

7. The preparation method of a multi-layer aluminum current collector according to claim 1, characterized in that: In step 1, the slurry contains a polyurethane adhesive, and the preparation method of the polyurethane adhesive is as follows: Under nitrogen as a protective gas, isophthalic acid, adipic acid, neopentyl glycol, and ethylene glycol are mixed, n-butyl titanate is added, and the mixture is stirred evenly, heated to 200-210°C and reacted for 2-4 hours, and then reacted at 240-250°C and -80--100KPa for 3-5 hours to obtain polyester polyol; Polyester polyol is added to ethyl acetate to obtain a polyester polyol solution, isocyanate is added to the polyester polyol solution, the mixture is fully stirred, and the mixture is allowed to stand at room temperature for 20 to 30 minutes to obtain a polyurethane adhesive.

8. The preparation method of a multi-layer aluminum current collector according to claim 7, characterized in that: The molar ratio of isophthalic acid, adipic acid, neopentyl glycol and ethylene glycol is (0.9-1.2):1.0:(1.7-1.9):(0.7-0.8), and the mass ratio of polyester polyol to isocyanate is 1:(0.04-0.08).

9. A multi-layer aluminum current collector, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 9.

10. Use of the multi-layer aluminum current collector according to claim 9 in a battery.