Conductive composite aluminum foil and preparation method thereof

Abstract

The invention discloses a conductive composite aluminum foil preparation method, which comprises: S1, carrying out a perforation treatment on a polymer base material, forming a plurality of perforations penetrating through the thickness direction in the polymer base material, and uniformly arranging the perforations in the surface of the polymer base material; s2, aluminum plating treatment is conducted on the first surface of the polymer base material obtained in the step S1, a first aluminum plating layer is obtained on the first surface of the polymer base material, and meanwhile a first side face aluminum plating layer is formed in each through hole; and S3, aluminum plating treatment is conducted on the second surface, obtained in the step S2, of the polymer base material, a second aluminum plating layer is obtained on the second surface of the polymer base material, and meanwhile a second side face aluminum plating layer is formed in each through hole. The composite aluminum foil prepared by the preparation method of the conduction type composite aluminum foil provided by the invention can solve the problem of non-uniform positive electrode current caused by sheet resistance difference of double surfaces of the composite aluminum foil.

Description

Technical Field

[0001] The present invention relates to the technical field of current collectors, and in particular to a conductive composite aluminum foil and a preparation method thereof. Background Art

[0002] As a new generation of basic material for lithium-ion batteries, composite aluminum foil is responsible for collecting the current generated by the positive electrode material and outputting it to the external circuit, completing the conversion process of chemical energy into electrical energy. At the same time, it serves as a support for the electrode coating layer, allowing the powdered active substance to adhere to it to form a continuous current channel.

[0003] At present, most composite aluminum foils are made of polymer materials such as PP / PET as the base material, and aluminum metal of the same thickness is prepared on both sides, which is similar to a sandwich structure. It has good conductivity, flexibility, oxidation resistance, and safety, and has become the preferred material for the positive electrode current collector of lithium-ion batteries. In the preparation process of composite aluminum foil, the thickness of the aluminum metal layer on both sides needs to be as close and uniform as possible, so as to keep the square resistance of the aluminum layer on both sides close and avoid the problem of uneven distribution of the positive electrode current of the lithium battery caused by thickness / square resistance fluctuations. In the actual aluminum layer preparation process, based on the standard single-sided square resistance of 40mΩ / □, the difference in aluminum layer thickness often causes the square resistance of each side to be in the range of 40±2mΩ / □, and the difference in the average square resistance of the other two sides is greater than 1mΩ / □, which leads to uneven distribution of the positive electrode current of lithium batteries. In order to make the square resistance of both sides reach the standard value, it is difficult to control the thickness of the aluminum layer during the coating process alone. Summary of the invention

[0004] The present invention aims to provide a conductive composite aluminum foil and a preparation method thereof, which can reduce the difference in square resistance between two sides of the composite aluminum foil and solve the problem of uneven current distribution at the positive electrode of a lithium battery.

[0005] Based on the above problems, the technical solution provided by the present invention is:

[0006] A method for preparing a conductive composite aluminum foil comprises the following steps:

[0007] S1, performing a perforation treatment on the polymer substrate to form a plurality of perforations penetrating the thickness direction of the polymer substrate, wherein the plurality of perforations are evenly arranged on the surface of the polymer substrate;

[0008] S2, performing aluminum plating on the first surface of the polymer substrate obtained in step S1, obtaining a first aluminum plating layer on the first surface of the polymer substrate, and forming a first side aluminum plating layer in each through hole;

[0009] S3, performing aluminum plating on the second surface of the polymer substrate obtained in step S2, obtaining a second aluminum plating layer on the second surface of the polymer substrate, and forming a second side aluminum plating layer in each through hole.

[0010] In some embodiments, the polymer substrate in step S1 is one of a PET substrate, a PP substrate, a PI substrate, and a PPS substrate.

[0011] In some embodiments, the thickness of the polymer substrate in step S1 is 5.85-6.15 μm.

[0012] In some embodiments, in step S1, the polymer substrate is perforated by laser processing, the hole diameter of the perforation is 0.05-0.55 mm, and the hole spacing is 2-8 mm.

[0013] In some of the embodiments, in step S1 , the plurality of through holes are arranged in a rectangular array.

[0014] In some embodiments, in step S2, aluminum is plated using an evaporation aluminum plating process, and the thickness of the first aluminum plating layer is 950-1050 nm.

[0015] In some embodiments, the thickness of the aluminum plating layer on the first side surface in step S2 is 475-525 nm.

[0016] In some embodiments, in step S3, aluminum is plated using an evaporation aluminum plating process, and the thickness of the second aluminum plating layer is 950-1050 nm.

[0017] In some embodiments, the thickness of the second side aluminum plating layer in step S3 is 475-525 nm.

[0018] Based on the above problems, the present invention also provides another technical solution:

[0019] A conductive composite aluminum foil is prepared according to any one of the above-mentioned methods for preparing the conductive composite aluminum foil.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] The polymer substrate is perforated and then aluminum is plated on both sides of the polymer substrate. A side aluminum layer is also formed in the perforation. The side aluminum layer can conduct electricity on both sides of the composite aluminum foil, reduce the fluctuation of square resistance caused by the thickness fluctuation of the double-sided aluminum layer, solve the problem of uneven current distribution at the positive electrode of the lithium battery, and reduce the process difficulty of controlling the thickness of the coating in the evaporation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. The accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 It is a partial structural schematic diagram of an embodiment of a conductive composite aluminum foil of the present invention;

[0024] Figure 2 A schematic diagram of the distribution of perforations in an embodiment of the present invention;

[0025] Figures 3 to 5 It is a schematic flow chart of a method for preparing a conductive composite aluminum foil of the present invention;

[0026] Figure 6 A schematic diagram of the double-sided square resistance of a composite aluminum foil prepared by a conventional method;

[0027] Figure 7 A schematic diagram of the double-sided square resistance of the composite aluminum foil prepared in an embodiment of the present invention;

[0028] in:

[0029] 100, polymer substrate; 200, first aluminum plating layer; 300, second aluminum plating layer;

[0030] 1. Polymer substrate; 1-1. Perforation;

[0031] 2. The first aluminum coating;

[0032] 3. Second aluminum coating;

[0033] 4. Aluminum coating on the first side;

[0034] 5. Aluminum coating on the second side. DETAILED DESCRIPTION

[0035] The above scheme is further described below in conjunction with specific examples. It should be understood that these examples are used to illustrate the present invention and are not limited to the scope of the present invention. The implementation conditions adopted in the examples can be further adjusted according to the conditions of the specific manufacturer, and the unspecified implementation conditions are usually the conditions in conventional experiments.

[0036] like Figures 3 to 5 As shown, a method for preparing a conductive composite aluminum foil comprises the following steps:

[0037] S1, performing a perforation treatment on the polymer substrate 1, forming a plurality of perforations 1-1 penetrating the polymer substrate 1 in a thickness direction, wherein the plurality of perforations 1-1 are evenly arranged on the surface of the polymer substrate 1;

[0038] S2, performing aluminum plating on the first surface of the polymer substrate 1 obtained in step S1, obtaining a first aluminum plating layer 2 on the first surface of the polymer substrate 1, and forming a first side aluminum plating layer 4 in each through hole 1-1;

[0039] S3, the second surface of the polymer substrate 1 obtained in step S2 is subjected to aluminum plating treatment to obtain a second aluminum plating layer 3 on the second surface of the polymer substrate 1, and a second side aluminum plating layer 5 is formed in each perforation 1-1. The structure of the obtained composite aluminum foil is as follows: Figure 1 shown.

[0040] In step S1 , the polymer substrate 1 is one of a PET substrate, a PP substrate, a PI substrate, and a PPS substrate, and the thickness of the polymer substrate 1 is 5.85 to 6.15 μm.

[0041] In step s1, the polymer substrate 1 is perforated by laser processing, the aperture of the perforation 1-1 is 0.05-0.55 mm, and the hole spacing is 2-8 mm. Preferably, the plurality of perforations 1-1 are arranged in a rectangular array, such as Figure 2 shown.

[0042] In order to improve the implementation effect of the present invention, the polymer substrate 1 needs to be washed and dried after the perforation treatment in step S1 to keep the polymer substrate 1 clean for the subsequent aluminum plating process. The laser process can be achieved by setting a laser device, a water washing device, and a drying device on the roll-to-roll equipment.

[0043] In step S2, aluminum is plated by evaporation aluminum plating process, and the thickness of the first aluminum plating layer 2 is 950-1050 nm. In step S2, the thickness of the first side aluminum plating layer 4 obtained in the through hole 1-1 is 475-525 nm.

[0044] In step s3, aluminum is plated by evaporation aluminum plating process, and the thickness of the second aluminum plating layer 3 is 950-1050nm. The thickness of the second side aluminum plating layer 5 obtained in the perforation 1-1 in step S3 is 475-525nm. The second side aluminum plating layer 5 is deposited on the first side aluminum plating layer 4, and at this time, the total thickness of the aluminum layer in the perforation is 950-1050nm.

[0045] The following is a specific implementation example for actual production needs, and the specific implementation steps are as follows:

[0046] S1. Perform laser perforation on a roll-to-roll laser machine on a polymer substrate with a size of W1650mm*L15000m*D6.0μm. The perforation width is 1590mm, the perforation diameter is 0.3mm±0.25mm, the hole spacing is 5±3mm, the winding speed is 100±50m / min, the unwinding tension is 200±100N, the winding tension is 150±80N, the laser speed is 1000±100mm / s, the jump speed is 10000±1000mm / s, the Q frequency is 30±2KHz, the Q release is 2±0.3us, and the current is 12±3A. After the processing, the roll film specification is W1650mm*L14800m*D6.0μm;

[0047] S2. Place the perforated roll film into a roll-to-roll evaporation coating machine for first surface aluminum evaporation, with a thickness of 1000±50nm and a laser perforated side wall evaporation thickness of 500±25nm. Set the ion source voltage to 2000±150V and the argon gas flow rate to 1000±100sccm. There are 56 evaporation boats in total, with an output current of 600±50A for each evaporation boat, an aluminum wire feeding speed of 6-30m / min, a winding speed of 30±10m / min, an unwinding tension of 300±30N, a winding tension of 250±20N, and a main roller cooling temperature of -40±10℃. After production, the first surface test resistance is within the range of 39-41mΩ / □. After processing, the roll film specification is W1650mm*L14400m*D7.0μm.

[0048] s3. The polymer substrate with the first surface aluminum coating is put into the roll-to-roll evaporation coating machine for the second surface aluminum coating, the vapor deposition thickness is 1000±50nm, and the laser perforated side wall is further vapor-deposited with 500±25nm thick aluminum on the basis of the existing 500nm aluminum layer, with a total thickness of about 1000nm, which is consistent with the thickness of the surface aluminum; the ion source voltage is set to 2000±150V, and the argon gas flow rate is 1000±100sccm; there are a total of 56 evaporation boats, and the output current value of each evaporation boat is 600±50A, the aluminum wire feeding speed is 6~30m / min, the winding speed is 30±10m / min, the unwinding tension is 330±30N, the winding tension is 280±20N, the main roller cooling temperature is -40±10℃, and the second surface test resistance after production is completed is in the range of 39~41mΩ / mouth. After the processing, the roll film specifications are W1650mm*L14000m*D8.0μm.

[0049] like Figure 6 As shown in the figure, the double-sided square resistance of the composite aluminum foil prepared by conventional methods is measured. The average square resistance of the first surface is 38mΩ / □, the average square resistance of the second surface is 41.6mΩ / □, and the square resistance difference of the two sides is >1mΩ / □. Figure 7 As shown, the double-sided square resistance of the composite aluminum foil obtained by the method of the present invention is measured. The average square resistance of the first surface is 39.6mΩ / □, the average square resistance of the second surface is 40.4mΩ / □, and the square resistance difference of the two sides is less than 1mΩ / □. It can be seen that the composite aluminum foil obtained by the method can reduce the difference in double-sided square resistance.

[0050] The following is a performance comparison table of the composite aluminum foil prepared by the present invention and the composite aluminum foil prepared by the conventional method:

[0051] Table 1 Comparison of composite aluminum foil properties

[0052]

[0053] It can be seen that the conductive composite aluminum foil can meet the use requirements and solve the problem of uneven current distribution at the positive electrode of lithium batteries.

[0054] In summary, the conductive composite aluminum foil prepared by this method can reduce the difference in square resistance between the two sides of the composite aluminum foil and solve the problem of uneven current distribution at the positive electrode of the lithium battery.

[0055] The above examples are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a conductive composite aluminum foil, characterized in that: The following steps are involved: S1, performing a perforation treatment on the polymer substrate to form a plurality of perforations penetrating the thickness direction of the polymer substrate, wherein the plurality of perforations are evenly arranged on the surface of the polymer substrate; S2, performing aluminum plating on the first surface of the polymer substrate obtained in step S1, obtaining a first aluminum plating layer on the first surface of the polymer substrate, and forming a first side aluminum plating layer in each through hole; S3, performing aluminum plating on the second surface of the polymer substrate obtained in step S2, obtaining a second aluminum plating layer on the second surface of the polymer substrate, and forming a second side aluminum plating layer in each through hole.

2. The method for preparing the conductive composite aluminum foil according to claim 1, characterized in that: In step S1, the polymer substrate is one of a PET substrate, a PP substrate, a PI substrate, and a PPS substrate.

3. The method for preparing the conductive composite aluminum foil according to claim 2, characterized in that: In step S1, the thickness of the polymer substrate is 5.85-6.15 μm.

4. The method for preparing the conductive composite aluminum foil according to claim 1, characterized in that: In step S1, the polymer substrate is perforated by laser processing, the diameter of the perforated holes is 0.05-0.55 mm, and the hole spacing is 2-8 mm.

5. The method for preparing the conductive composite aluminum foil according to claim 4, characterized in that: In step S1, a plurality of perforations are arranged in a rectangular array.

6. The method for preparing the conductive composite aluminum foil according to claim 1, characterized in that: In step S2, aluminum is plated by evaporation aluminum plating process, and the thickness of the first aluminum plating layer is 950-1050nm.

7. The method for preparing the conductive composite aluminum foil according to claim 1, characterized in that: The thickness of the aluminum plating layer on the first side surface in step S2 is 475-525 nm.

8. The method for preparing the conductive composite aluminum foil according to claim 1, characterized in that: In step S3, aluminum is plated by evaporation aluminum plating process, and the thickness of the second aluminum plating layer is 950-1050 nm.

9. The method for preparing the conductive composite aluminum foil according to claim 1, characterized in that: In step S3, the thickness of the second side aluminum plating layer is 475-525 nm.

10. A conductive composite aluminum foil, characterized in that: The conductive composite aluminum foil is prepared according to the method for preparing the conductive composite aluminum foil according to any one of claims 1 to 9.

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