WO2024086982A1

WO2024086982A1 - Positive electrode composite aluminum current collector and preparation method therefor, and electrochemical device

Info

Publication number: WO2024086982A1
Application number: PCT/CN2022/127088
Authority: WO
Inventors: 王成豪; 李学法; 张国平
Original assignee: 扬州纳力新材料科技有限公司
Priority date: 2022-10-24
Filing date: 2022-10-24
Publication date: 2024-05-02

Abstract

The present application provides a preparation method for a positive electrode composite aluminum current collector, comprising the following steps: providing a polymer substrate, the polymer substrate comprising a first surface and a second surface opposite to the first surface; placing the polymer substrate and metallic aluminum in a deposition chamber, and vacuumizing the deposition chamber; heating the metallic aluminum to vaporize the metallic aluminum to form aluminum vapor, and injecting plasma gas into the deposition chamber while the metallic aluminum is vaporized, such that the plasma gas crystallizes the aluminum vapor to form aluminum particles; and depositing the aluminum particles on the first surface and the second surface to obtain a first aluminum layer and a second aluminum layer, respectively, wherein the conductivity of the first aluminum layer and/or the conductivity of the second aluminum layer are isotropic. The positive electrode composite aluminum current collector prepared by the present application has relatively high safety. The present application further provides a positive electrode composite aluminum current collector and an electrochemical device.

Description

Positive electrode composite aluminum current collector and preparation method thereof, and electrochemical device

Technical Field

The present application relates to the field of battery technology, and in particular to a positive electrode composite aluminum current collector, a preparation method thereof, and an electrochemical device.

Background technique

At present, high-purity aluminum foil is usually used as the positive electrode current collector of electrochemical devices (such as batteries). Among them, in the preparation process of aluminum current collector, aluminum crystals need to be subjected to calendering treatment. However, during the calendering process, aluminum crystals are subjected to tensile stress, resulting in defects and distortions in the internal lattice of metal aluminum, leading to enhanced electron scattering. At the same time, calendering cold processing affects the interatomic bonding properties, resulting in an increase in the resistivity of the aluminum foil current collector in the vertical welding direction, causing the aluminum foil current collector to have a large resistance in the vertical welding direction after being welded to the pole ear, resulting in very high heat generated at the pole ear welding during the battery charging and discharging process, which not only increases the internal resistance of the battery, but also reduces the safety of the battery.

Summary of the invention

Based on this, it is necessary to provide a method for preparing a positive electrode composite aluminum current collector that can improve safety.

In addition, it is also necessary to provide a positive electrode composite aluminum current collector prepared by the above preparation method.

In addition, it is also necessary to provide an electrochemical device.

At least one embodiment of the present application provides a method for preparing a positive electrode composite aluminum current collector, comprising the following steps:

Providing a polymer substrate, the polymer substrate comprising a first surface and a second surface opposite to the first surface;

Placing the polymer substrate and metal aluminum in a vapor deposition chamber, and evacuating the vapor deposition chamber;

Heating the metal aluminum to evaporate the metal aluminum to form aluminum vapor, and injecting plasma gas into the evaporation chamber while the metal aluminum is evaporating, so that the plasma gas promotes the aluminum vapor to crystallize to form aluminum particles; and

The aluminum particles are deposited on the first surface and the second surface to obtain a first aluminum layer and a second aluminum layer, respectively;

The electrical conductivity of the first aluminum layer and/or the electrical conductivity of the second aluminum layer are isotropic.

In some embodiments, the plasma gas includes at least one of helium plasma gas, neon plasma gas, argon plasma gas, krypton plasma gas, xenon plasma gas, and radon plasma gas.

In some embodiments, the preparation method comprises at least one of the following (1) to (5):

(1) The concentration of the aluminum vapor is 60 mol/L-80 mol/L;

(2) The evaporation temperature of the metal aluminum is 600° C. to 1600° C.;

(3) The evaporation speed of the metal aluminum is 10 m/min to 100 m/min;

(4) The pulse time of the plasma gas is (5-10) s/time;

(5) The injection amount of the plasma gas is (10-200) mol/time.

At least one embodiment of the present application provides a positive electrode composite aluminum current collector prepared by the preparation method, comprising a polymer substrate and a first aluminum layer and a second aluminum layer respectively located on both sides of the polymer substrate;

In some embodiments, the positive electrode composite aluminum current collector includes at least one of the following (1) to (2):

(1) The difference between the electrical conductivity of the first aluminum layer in each direction is less than or equal to 5%;

(2) The difference between the electrical conductivities of the second aluminum layer in various directions is less than or equal to 5%.

In some embodiments, the positive electrode composite aluminum current collector includes at least one of the following (1) to (5):

(1) The puncture strength of the positive electrode composite aluminum current collector is ≥ 200 gf;

(2) In the processing direction, the tensile strength of the positive electrode composite aluminum current collector is ≥150 MPa;

(3) In the transverse direction perpendicular to the processing direction, the tensile strength of the positive electrode composite aluminum current collector is ≥150 MPa;

(4) In the processing direction, the elongation of the positive electrode composite aluminum current collector is ≥10%;

(5) In the transverse direction perpendicular to the processing direction, the elongation of the positive electrode composite aluminum current collector is ≥10%.

In some embodiments, the positive electrode composite aluminum current collector includes at least one of the following (1) to (4):

(1) The thickness of the positive electrode composite aluminum current collector is 5 μm to 30 μm;

(2) The thickness of the polymer substrate is 3 μm to 25 μm;

(3) The thickness of the first aluminum layer is 0.3 μm to 3.0 μm;

(4) The thickness of the second aluminum layer is 0.3 μm to 3.0 μm.

In some embodiments, the polymer substrate includes at least one of the following (1) to (5):

(1) The puncture strength of the polymer substrate is ≥ 200 gf;

(2) In the processing direction, the tensile strength of the polymer substrate is ≥160 MPa;

(3) In the transverse direction perpendicular to the processing direction, the tensile strength of the polymer substrate is ≥160 MPa;

(4) In the processing direction, the elongation of the polymer substrate is ≥30%;

(5) In the transverse direction perpendicular to the processing direction, the elongation of the polymer substrate is ≥30%.

In some embodiments, the material of the polymer substrate includes at least one of an insulating polymer material, an insulating polymer composite material, a conductive polymer material and a conductive polymer composite material.

In some embodiments, the polymer substrate includes at least one of the following (1) to (4):

(1) The insulating polymer material is selected from at least one of polyamide, polyethylene terephthalate, polyethylene terephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, aramid, polyphenylene dicarboxamide, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, poly(p-phenylene terephthalamide), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, polycarbonate, cellulose and its derivatives, starch and its derivatives, protein and its derivatives, polyvinyl alcohol and its crosslinked products, polyethylene glycol and its crosslinked products;

(2) The insulating polymer composite material is selected from a composite material formed by an insulating polymer material and an inorganic material, and the inorganic material is selected from at least one of a ceramic material, a glass material and a ceramic composite material;

(3) The conductive polymer material is selected from at least one of doped polysulfur nitride and doped polyacetylene;

(4) The conductive polymer composite material is selected from a composite material formed by an insulating polymer material and a conductive material, the conductive material is selected from at least one of a conductive carbon material, a metal material and a composite conductive material, the conductive carbon material is selected from at least one of carbon black, carbon nanotubes, graphite, acetylene black and graphene, the metal material is selected from at least one of nickel, nickel alloy, iron, iron alloy, copper, copper alloy, aluminum and aluminum alloy, and the composite conductive material is selected from at least one of nickel-coated graphite powder and nickel-coated carbon fiber.

(1) The purity of the first aluminum layer is ≥99.8%;

(2) The purity of the second aluminum layer is ≥99.8%.

(1) The sheet resistance of the first aluminum layer is ≤50 mΩ;

(2) The sheet resistance of the second aluminum layer is ≤50 mΩ.

At least one embodiment of the present application provides an electrochemical device, including a positive electrode composite aluminum current collector prepared by the preparation method or including the positive electrode composite aluminum current collector.

In the present application, the surface of the polymer substrate is thickened by the process of aluminum atomic deposition, and the crystallization direction of the aluminum crystals is optimized. Due to the atomic deposition process, the first aluminum layer and the second aluminum layer prepared are not affected by external forces, which protects the integrity of the internal lattice during the crystallization process, avoids the enhancement of electron scattering, and ensures that the conductivity of the first aluminum layer and the second aluminum layer is isotropic, thereby reducing the resistivity of the positive electrode composite aluminum current collector in the vertical welding direction, reducing the heat generated at the electrode ear welding during the charging and discharging process of the electrochemical device, thereby reducing the internal resistance of the electrochemical device, and also improving the safety of the electrochemical device.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better describe and illustrate the embodiments and/or examples of the present application, reference may be made to one or more drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of the disclosed application, the embodiments and/or examples currently described, and any of the best modes of these applications currently understood.

FIG1 is a flow chart of the preparation of the positive electrode composite aluminum current collector provided in the present application;

FIG2 is a schematic diagram of the structure of the positive electrode composite aluminum current collector provided in the present application;

FIG. 3 is a module composition diagram of the electrochemical device provided in the present application.

Figure numerals: 10 - polymer substrate; 101 - first surface; 102 - second surface; 20 - first aluminum layer; 30 - second aluminum layer; 100 - positive electrode composite aluminum current collector; 200 - electrochemical device.

Detailed ways

In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and/or" used herein includes any and all combinations of one or more related listed items.

Referring to FIG. 1 , at least one embodiment of the present application provides a method for preparing a positive electrode composite aluminum current collector, comprising the following steps:

Step S11 , please refer to FIG. 2 , providing a polymer substrate 10 .

The polymer substrate 10 includes a first surface 101 and a second surface 102 opposite to the first surface 101.

In one embodiment, the thickness of the polymer substrate 10 is 3 μm to 25 μm. Preferably, the thickness of the polymer substrate 10 is 4 μm to 8 μm. If the thickness of the polymer substrate 10 is too small and the strength is too low, the polymer substrate 10 is easy to break during the subsequent processing; if the thickness of the polymer substrate 10 is too large, the production cost will be too high, and the cost of the subsequent prepared positive electrode composite aluminum current collector will also be too high.

In one embodiment, the puncture strength of the polymer substrate 10 is ≥ 200 gf.

In one embodiment, in the machine direction (MD), the tensile strength of the polymer substrate 10 is ≥160 MPa. In one embodiment, in the transverse direction (TD) perpendicular to the machine direction (MD), the tensile strength of the polymer substrate 10 is ≥160 MPa.

In one embodiment, in the machine direction (MD), the elongation of the polymer substrate 10 is ≥30%. In one embodiment, in the transverse direction (TD) perpendicular to the machine direction (MD), the elongation of the polymer substrate 10 is ≥30%.

In one embodiment, the material of the polymer substrate 10 includes at least one of an insulating polymer material, an insulating polymer composite material, a conductive polymer material, and a conductive polymer composite material.

In one embodiment, the insulating polymer material is selected from at least one of polyamide, polyethylene terephthalate, polyethylene terephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, aramid, polyphenylene dicarboxylate, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, polyparaphenylene terephthalamide, polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, polycarbonate, cellulose and its derivatives, starch and its derivatives, protein and its derivatives, polyvinyl alcohol and its crosslinked products, polyethylene glycol and its crosslinked products.

In one embodiment, the insulating polymer composite material is selected from a composite material formed by an insulating polymer material and an inorganic material. In one embodiment, the inorganic material is selected from at least one of a ceramic material, a glass material and a ceramic composite material.

In one embodiment, the conductive polymer material is selected from at least one of doped polysulfur nitride and doped polyacetylene.

In one embodiment, the conductive polymer composite material is selected from a composite material formed by an insulating polymer material and a conductive material. In one embodiment, the conductive material is selected from at least one of a conductive carbon material, a metal material, and a composite conductive material. In one embodiment, the conductive carbon material is selected from at least one of carbon black, carbon nanotubes, graphite, acetylene black, and graphene. In one embodiment, the metal material is selected from at least one of nickel, nickel alloy, iron, iron alloy, copper, copper alloy, aluminum, and aluminum alloy. In one embodiment, the composite conductive material is selected from at least one of nickel-coated graphite powder and nickel-coated carbon fiber.

Step S12: placing the polymer substrate 10 and metal aluminum in a vapor deposition chamber, and evacuating the vapor deposition chamber.

In one embodiment, the metallic aluminum may be a high-purity aluminum block.

Step S13, heating the metal aluminum to evaporate the metal aluminum to form aluminum vapor, and injecting plasma gas into the evaporation chamber while the metal aluminum is evaporating, so that the plasma gas promotes the aluminum vapor to crystallize to form aluminum particles.

In one embodiment, the plasma gas includes at least one of helium plasma gas, neon plasma gas, argon plasma gas, krypton plasma gas, xenon plasma gas and radon plasma gas. Preferably, the plasma gas is argon plasma gas.

In one embodiment, the concentration of the aluminum vapor is 60 mol/L-80 mol/L.

In one embodiment, the evaporation temperature of the metal aluminum is 600°C to 1600°C.

In one embodiment, the evaporation speed of the metal aluminum is 10 m/min to 100 m/min.

In one embodiment, the pulse time of the plasma gas is (5-10) s/time.

In one embodiment, the injection amount of the plasma gas is (10-200) mol/time.

Step S14: The aluminum particles are deposited on the first surface 101 and the second surface 102 to obtain a first aluminum layer 20 and a second aluminum layer 30 respectively, thereby obtaining a positive electrode composite aluminum current collector 100.

The electrical conductivity of the first aluminum layer 20 and/or the electrical conductivity of the second aluminum layer 30 are isotropic. In one embodiment, the difference between the electrical conductivity of the first aluminum layer 20 in various directions is less than or equal to 5%. In one embodiment, the difference between the electrical conductivity of the second aluminum layer 30 in various directions is less than or equal to 5%.

In one embodiment, the thickness of the first aluminum layer 20 is 0.3 μm to 3.0 μm. In one embodiment, the thickness of the second aluminum layer 30 is 0.3 μm to 3.0 μm.

In one embodiment, the purity of the first aluminum layer 20 is ≥ 99.8%. In one embodiment, the purity of the second aluminum layer 30 is ≥ 99.8%.

In one embodiment, the sheet resistance of the first aluminum layer 20 is ≤50 mΩ. In one embodiment, the sheet resistance of the second aluminum layer 30 is ≤50 mΩ.

In one embodiment, the puncture strength of the positive electrode composite aluminum current collector 100 is ≥ 200 gf.

In one embodiment, in the machine direction (MD), the tensile strength of the positive composite aluminum current collector 100 is ≥150 MPa. In one embodiment, in the transverse direction (TD) perpendicular to the machine direction (MD), the tensile strength of the positive composite aluminum current collector 100 is ≥150 MPa.

In one embodiment, in the machine direction (MD), the elongation of the positive composite aluminum current collector 100 is ≥ 10%. In one embodiment, in the transverse direction (TD) perpendicular to the machine direction (MD), the elongation of the positive composite aluminum current collector 100 is ≥ 10%.

In one embodiment, the thickness of the positive electrode composite aluminum current collector 100 is 5 μm to 30 μm.

In one embodiment, after the positive electrode composite aluminum current collector 100 is prepared, the positive electrode composite aluminum current collector 100 may be rolled up. In one embodiment, the tension for rolling up the positive electrode composite aluminum current collector 100 is 5N to 25N.

Please refer to FIG. 2 again. At least one embodiment of the present application provides a positive electrode composite aluminum current collector 100 prepared by the above-mentioned preparation method. The positive electrode composite aluminum current collector 100 includes a polymer substrate 10 and a first aluminum layer 20 and a second aluminum layer 30 respectively located on both sides of the polymer substrate 10 .

The polymer substrate 10 includes a first surface 101 and a second surface 102 opposite to the first surface 101 .

In one embodiment, the thickness of the polymer substrate 10 is 3 μm to 25 μm. Preferably, the thickness of the polymer substrate 10 is 4 μm to 8 μm.

The first aluminum layer 20 and the second aluminum layer 30 are respectively located on the first surface 101 and the second surface 102. The conductivity of the first aluminum layer 20 and/or the conductivity of the second aluminum layer 30 are isotropic. In one embodiment, the difference between the conductivity of the first aluminum layer 20 in various directions is less than or equal to 5%. In one embodiment, the difference between the conductivity of the second aluminum layer 30 in various directions is less than or equal to 5%.

Referring to FIG. 3 , at least one embodiment of the present application provides an electrochemical device 200, wherein the electrochemical device 200 includes the positive electrode composite aluminum current collector 100 prepared by the above preparation method or includes the above positive electrode composite aluminum current collector 100. In one embodiment, the electrochemical device 200 may be a battery. Specifically, the battery may be a secondary battery. More specifically, the secondary battery may be a non-aqueous secondary battery.

In the present application, the surface of the polymer substrate 10 is thickened by the process of aluminum atomic deposition, and the crystallization direction of the aluminum crystals is optimized. Due to the atomic deposition process, the first aluminum layer 20 and the second aluminum layer 30 prepared are not affected by external forces, which protects the integrity of the internal lattice during the crystallization process, avoids the enhancement of electron scattering, and ensures that the first aluminum layer 20 and the second aluminum layer 30 are isotropic in conductivity, thereby reducing the resistivity of the positive electrode composite aluminum current collector 100 in the vertical welding direction, reducing the heat generated at the electrode ear welding during the charging and discharging process of the electrochemical device 200, thereby reducing the internal resistance of the electrochemical device 200, and also improving the safety of the electrochemical device 200.

The present application is further described below through specific examples and comparative examples.

Example 1

(1) A polyethylene terephthalate (PET) with a thickness of 6 μm is used as a polymer substrate, wherein the polymer substrate includes a first surface and a second surface opposite to the first surface.

(2) Placing the polymer substrate and high-purity aluminum in a vapor deposition chamber, and evacuating the vapor deposition chamber.

(3) High-purity aluminum is heated to evaporate the high-purity aluminum to form aluminum vapor, and while the high-purity aluminum is evaporating, argon plasma gas is injected into the evaporation chamber at a fixed time through the ion source on the equipment, so that the argon plasma gas promotes the crystallization of the aluminum vapor to form aluminum particles. Among them, the concentration of aluminum vapor is 70 mol/L, the evaporation temperature of the high-purity aluminum is 800°C, the evaporation speed of the high-purity aluminum is 30 m/min, the pulse time of the argon plasma gas is 8 s/time, and the injection amount of the argon plasma gas is 50 mol/time.

(4) Aluminum particles are deposited on the first surface and the second surface to obtain a first aluminum layer and a second aluminum layer, respectively, thereby preparing a positive electrode composite aluminum current collector with a thickness of 8 μm.

(5) Rolling up the positive electrode composite aluminum current collector. The tension for rolling up the positive electrode composite aluminum current collector is 5N.

Comparative Example 1

(1) The electrolytic aluminum melt is sent to a smelting furnace, and aluminum ingots accounting for 30% of the total weight of the electrolytic aluminum melt are added, the melt temperature is controlled to be 770°C, and the mass percentages of the elements in the melt are adjusted to be Si: 0.15%, Fe: 0.48%, Cu: 0.13%, Mn: 1.3%, Ti: 0.03%, and the balance is Al; pure nitrogen or pure argon is used to spray a refining agent into the melt for refining, and the melt is fully stirred for 9 minutes, and then the melt is allowed to stand for 20 minutes to remove the scum on the surface of the aluminum melt, and the melt is poured into a standing furnace, and the temperature in the standing furnace is controlled to be 755°C; the aluminum melt in the standing furnace is sent to a launder, and aluminum-titanium-boron wire is added in reverse to refine the grains, and then the aluminum melt is degassed with pure nitrogen or pure argon in a degassing box, and after degassing, the aluminum melt is filtered and purified with a foam ceramic filter; the purified aluminum melt is sent to a casting and rolling mill for casting and rolling, and a billet with a thickness of 8.0 mm is cast and rolled.

(2) The above-mentioned billet with a thickness of 8.0 mm is cold-rolled to obtain a billet with a thickness of 4.0 mm.

(3) The 4.0 mm thick blank in (2) is subjected to homogenization annealing at a temperature of 470° C. and a homogenization annealing time of 25 h.

(4) The annealed billet is cold rolled to a thickness of 0.5 mm, and then subjected to recrystallization annealing, wherein the temperature of the recrystallization annealing is 300° C. and the recrystallization annealing time is 15 h.

(5) The thickness of the billet after recrystallization annealing is rolled to 8 μm to obtain a positive electrode aluminum foil current collector.

(I) The positive electrode composite aluminum current collector prepared in Example 1 and the positive electrode aluminum foil current collector prepared in Comparative Example 1 were tested for thickness, conductivity difference of the aluminum layer in the current collector in various directions, elongation in the machining direction (MD), and elongation in the transverse direction (TD). The test results are shown in Table 1 below.

Table 1

产品特性Product Features	实施例1Example 1	对比例1Comparative Example 1
厚度(μm)Thickness(μm)	88	88
铝层在各个方向上的电导率差异(％)Difference in conductivity of aluminum layer in various directions (%)	11	66
在MD上的延伸率(％)Elongation in MD (%)	9595	9292
在TD上的延伸率(％)Elongation in TD (%)	9090	8888

From the test results in Table 1 above, it can be seen that the conductivity difference of the aluminum layer (i.e., the first aluminum layer and the second aluminum layer) in the positive composite aluminum current collector prepared in Example 1 in each direction is much smaller than the conductivity difference in each direction of the positive aluminum foil current collector prepared in Comparative Example 1. This shows that compared with the positive aluminum foil current collector prepared in Comparative Example 1, the first aluminum layer and the second aluminum layer in the positive composite aluminum current collector prepared in Example 1 have better isotropic conductivity.

(ii) The positive electrode composite aluminum current collector prepared in Example 1 and the positive electrode aluminum foil current collector prepared in Comparative Example 1 were respectively prepared into ternary lithium batteries with a capacity of 100AH, and the internal resistance of the ternary lithium batteries and the number of cycles when the capacity dropped to 80% were tested respectively. The test results are shown in Table 2 below.

Among them, when testing the internal resistance of the ternary lithium battery and the number of cycles when the capacity drops to 80%, 10 ternary lithium batteries are taken for testing, and the average value of the tests of the 10 ternary lithium batteries is taken as the final test result.

Table 2

It can be seen from Table 2 above that the ternary lithium battery prepared with the positive electrode composite aluminum current collector in Example 1 has lower internal resistance and better cycle life than the ternary lithium battery prepared with the positive electrode aluminum foil current collector in Comparative Example 1.

The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

A method for preparing a positive electrode composite aluminum current collector, characterized in that it comprises the following steps:

Providing a polymer substrate, the polymer substrate comprising a first surface and a second surface opposite to the first surface;

Placing the polymer substrate and metal aluminum in a vapor deposition chamber, and evacuating the vapor deposition chamber;

Heating the metal aluminum to evaporate the metal aluminum to form aluminum vapor, and injecting plasma gas into the evaporation chamber while the metal aluminum is evaporating, so that the plasma gas causes the aluminum vapor to crystallize to form aluminum particles; and

The aluminum particles are deposited on the first surface and the second surface to obtain a first aluminum layer and a second aluminum layer, respectively;

The electrical conductivity of the first aluminum layer and/or the electrical conductivity of the second aluminum layer are isotropic.
The method for preparing a positive electrode composite aluminum current collector according to claim 1, characterized in that the plasma gas includes at least one of helium plasma gas, neon plasma gas, argon plasma gas, krypton plasma gas, xenon plasma gas and radon plasma gas.
The method for preparing the positive electrode composite aluminum current collector according to claim 1, characterized in that the preparation method comprises at least one of the following (1) to (5):

(1) The concentration of the aluminum vapor is 60 mol/L-80 mol/L;

(2) The evaporation temperature of the metal aluminum is 600° C. to 1600° C.;

(3) The evaporation speed of the metal aluminum is 10 m/min to 100 m/min;

(4) The pulse time of the plasma gas is (5-10) s/time;

(5) The injection amount of the plasma gas is (10-200) mol/time.
A positive electrode composite aluminum current collector prepared by the preparation method according to any one of claims 1 to 3, characterized in that it comprises a polymer substrate and a first aluminum layer and a second aluminum layer respectively located on both sides of the polymer substrate;

The electrical conductivity of the first aluminum layer and/or the electrical conductivity of the second aluminum layer are isotropic.
The positive electrode composite aluminum current collector according to claim 4, characterized in that the positive electrode composite aluminum current collector comprises at least one of the following (1) to (2):

(1) The difference between the electrical conductivity of the first aluminum layer in each direction is less than or equal to 5%;

(2) The difference between the electrical conductivities of the second aluminum layer in various directions is less than or equal to 5%.
The positive electrode composite aluminum current collector according to claim 4, characterized in that the positive electrode composite aluminum current collector comprises at least one of the following (1) to (5):

(1) The puncture strength of the positive electrode composite aluminum current collector is ≥ 200 gf;

(2) In the processing direction, the tensile strength of the positive electrode composite aluminum current collector is ≥150 MPa;

(3) In the transverse direction perpendicular to the processing direction, the tensile strength of the positive electrode composite aluminum current collector is ≥150 MPa;

(4) In the processing direction, the elongation of the positive electrode composite aluminum current collector is ≥10%;

(5) In the transverse direction perpendicular to the processing direction, the elongation of the positive electrode composite aluminum current collector is ≥10%.
The positive electrode composite aluminum current collector according to claim 4, characterized in that the positive electrode composite aluminum current collector comprises at least one of the following (1) to (4):

(1) The thickness of the positive electrode composite aluminum current collector is 5 μm to 30 μm;

(2) The thickness of the polymer substrate is 3 μm to 25 μm;

(3) The thickness of the first aluminum layer is 0.3 μm to 3.0 μm;

(4) The thickness of the second aluminum layer is 0.3 μm to 3.0 μm.
The positive electrode composite aluminum current collector according to claim 4, characterized in that the polymer substrate comprises at least one of the following (1) to (5):

(1) The puncture strength of the polymer substrate is ≥ 200 gf;

(2) In the processing direction, the tensile strength of the polymer substrate is ≥160 MPa;

(3) In the transverse direction perpendicular to the processing direction, the tensile strength of the polymer substrate is ≥160 MPa;

(4) In the processing direction, the elongation of the polymer substrate is ≥30%;

(5) In the transverse direction perpendicular to the processing direction, the elongation of the polymer substrate is ≥30%.
The positive electrode composite aluminum current collector according to any one of claims 4 to 8 is characterized in that the material of the polymer substrate includes at least one of an insulating polymer material, an insulating polymer composite material, a conductive polymer material and a conductive polymer composite material.
The positive electrode composite aluminum current collector according to claim 9, characterized in that the polymer substrate comprises at least one of the following (1) to (4):

(1) The insulating polymer material is selected from at least one of polyamide, polyethylene terephthalate, polyethylene terephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, aramid, polyphenylene dicarboxamide, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, poly(p-phenylene terephthalamide), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, polycarbonate, cellulose and its derivatives, starch and its derivatives, protein and its derivatives, polyvinyl alcohol and its crosslinked products, polyethylene glycol and its crosslinked products;

(2) The insulating polymer composite material is selected from a composite material formed by an insulating polymer material and an inorganic material, and the inorganic material is selected from at least one of a ceramic material, a glass material and a ceramic composite material;

(3) The conductive polymer material is selected from at least one of doped polysulfur nitride and doped polyacetylene;

(4) The conductive polymer composite material is selected from a composite material formed by an insulating polymer material and a conductive material, the conductive material is selected from at least one of a conductive carbon material, a metal material and a composite conductive material, the conductive carbon material is selected from at least one of carbon black, carbon nanotubes, graphite, acetylene black and graphene, the metal material is selected from at least one of nickel, nickel alloy, iron, iron alloy, copper, copper alloy, aluminum and aluminum alloy, and the composite conductive material is selected from at least one of nickel-coated graphite powder and nickel-coated carbon fiber.
The positive electrode composite aluminum current collector according to any one of claims 4 to 8, characterized in that the positive electrode composite aluminum current collector comprises at least one of the following (1) to (2):

(1) The purity of the first aluminum layer is ≥99.8%;

(2) The purity of the second aluminum layer is ≥99.8%.
The positive electrode composite aluminum current collector according to any one of claims 4 to 8, characterized in that the positive electrode composite aluminum current collector comprises at least one of the following (1) to (2):

(1) The sheet resistance of the first aluminum layer is ≤50 mΩ;

(2) The sheet resistance of the second aluminum layer is ≤50 mΩ.
An electrochemical device, characterized in that it comprises a positive electrode composite aluminum current collector prepared by the preparation method according to any one of claims 1 to 3 or comprises a positive electrode composite aluminum current collector according to any one of claims 4 to 12.