Porous composite aluminum foil, preparation method thereof and battery pole piece

Abstract

The present application relates to the technical field of battery pole piece current collector, and specifically discloses a porous composite aluminum foil, a preparation method thereof and a battery pole piece. The porous composite aluminum foil comprises a base film; the base film has a plurality of through holes in the thickness direction, and the through holes are double-cone-shaped holes; and an aluminum metal layer is deposited on the inner walls of the through holes and both sides of the base film. The composite aluminum foil has excellent electrical conductivity, electrolyte wettability and rate performance, and can be cut arbitrarily without affecting the electrical conductivity. The preparation method of the porous composite aluminum foil comprises the following steps: firstly, a base film with double-cone-shaped holes is obtained by using heavy ion irradiation technology; and then an aluminum metal layer is deposited on the upper and lower sides of the base film to obtain the porous composite aluminum foil, so that the large-scale production of the porous composite aluminum foil can be realized. The application of the porous composite aluminum foil includes battery pole pieces. The battery pole piece contains the porous composite aluminum foil and has high energy density and power density.

Description

Technical Field

[0001] This invention relates to the field of battery electrode current collector technology, specifically to a porous composite aluminum foil, its preparation method, and a battery electrode. Background Technology

[0002] Lithium-ion batteries are widely used in new energy vehicles due to their high specific energy density and good cycle stability. However, electric vehicles currently face some challenges, such as slow charging, short lifespan, short driving range, and safety issues. To further improve the energy density and power density of lithium batteries to meet the demands of electric vehicles for fast charging and discharging and ultra-long driving range, it is necessary to optimize battery components. Most research focuses on improving the positive and negative electrode materials and electrolytes, but neglects the optimization of current collectors. As an inactive material, the current collector accounts for up to 15% of the weight, so optimizing the current collector has great potential to improve battery performance.

[0003] The current collector has a crucial impact on battery performance. A high-performance current collector should possess characteristics such as high conductivity, high strength, high flexibility, and ultra-thinness. To further improve battery energy density, commercial aluminum current collectors have been continuously thinned from the initial 25 μm, and currently to 10 μm or even 8 μm. However, further thinning is not only difficult to achieve in terms of manufacturing processes, but also significantly reduces the mechanical properties of the current collector. To further reduce the weight of the current collector to improve energy density, while simultaneously maintaining a certain level of mechanical strength, the industry is now turning to composite aluminum current collectors. The preparation method is as follows: first, an organic thin film is selected as the base film, and then aluminum metal layers are deposited on both sides of the film for conductivity. This combination of organic film and metal satisfies the requirements for high strength, high flexibility, and ultra-thinness, while also solving the problem of internal short circuits caused by burrs generated after puncturing traditional aluminum foil.

[0004] However, existing composite aluminum foils cannot meet the requirements for high conductivity because their base film is an insulating polymer material, allowing current to pass only through the outer aluminum metal layer. Once cut, the top and bottom surfaces of the composite aluminum foil become disconnected, requiring an additional welding process to establish conductivity, which complicates the process and increases costs. Good conductivity is a prerequisite for high-rate battery performance, therefore, there is an urgent need to develop new high-conductivity composite aluminum foils. Summary of the Invention

[0005] To address the issues of existing pure aluminum foil's inability to achieve high conductivity, ultra-thin thickness, and high mechanical properties, and the poor conductivity of commercial composite aluminum foil, this invention provides a porous composite aluminum foil. This composite aluminum foil comprises a base film with biconical pores and an aluminum metal layer deposited on the base film, thus possessing both high conductivity and good mechanical properties.

[0006] The present invention also aims to provide a method for preparing the porous composite aluminum foil. This method first utilizes heavy ion irradiation technology to obtain a base film with biconical pores, and then deposits aluminum metal layers on both sides of the base film to obtain the porous composite aluminum foil.

[0007] Another object of the present invention is to provide applications of the porous composite aluminum foil, including its application in the preparation of battery electrodes.

[0008] Another object of the present invention is a battery electrode containing the aforementioned porous composite aluminum foil. This battery electrode, containing the aforementioned porous composite aluminum foil, has high energy density and power density.

[0009] The objective of this invention is achieved through the following technical solution.

[0010] A porous composite aluminum foil includes a base film; the base film has a plurality of channels extending along the thickness direction, the channels being double-conical channels; aluminum metal layers are deposited on both sides of the base film and on the inner walls of the channels.

[0011] As a preferred embodiment of the porous composite aluminum foil of the present invention, the double conical channel includes a first conical channel whose diameter gradually decreases along a first thickness direction, and a second conical channel whose size gradually decreases along a second thickness direction opposite to the first thickness direction, wherein the first conical channel and the second conical channel are connected.

[0012] As a further preferred embodiment of the porous composite aluminum foil of the present invention, the first tapered channel and the second tapered channel are concentrically connected along the thickness direction.

[0013] As a further preferred embodiment of the porous composite aluminum foil of the present invention, the diameter of the large pore end of the first conical channel is 1-6 μm, and the diameter of the small pore end is 500 nm-3 μm.

[0014] As a further preferred embodiment of the porous composite aluminum foil of the present invention, the diameter of the large pore end of the second conical channel is 1-6 μm, and the diameter of the small pore end is 500 nm-3 μm.

[0015] In a preferred embodiment of the porous composite aluminum foil of the present invention, the double conical channel is an hourglass-shaped channel.

[0016] As a further preferred embodiment of the porous composite aluminum foil of the present invention, the diameter of the large pore end of the double conical channel is 1-6 μm, and the diameter of the small pore end is 500 nm-3 μm.

[0017] In a preferred embodiment of the porous composite aluminum foil of the present invention, the thickness of the base film is 6-30 μm.

[0018] In a preferred embodiment of the porous composite aluminum foil of the present invention, the pore density of the base film is 10. 4 -10 7 pcs / cm 2 .

[0019] As a preferred embodiment of the composite aluminum foil of the present invention, the base film is made of polyethylene terephthalate (PET), polyimide (PI), polyethersulfone resin (PES), polyetherimide (PEI), polyethylene naphthalate (PEN), or polypropylene (PP).

[0020] In a preferred embodiment of the porous composite aluminum foil of the present invention, the thickness of the aluminum metal layer is 100 nm-2 μm.

[0021] A method for preparing a porous composite aluminum foil includes the following steps:

[0022] S1. The organic polymer film is subjected to heavy ion irradiation treatment to obtain an organic polymer film irradiated with heavy ions.

[0023] S2. The organic polymer film irradiated by heavy ions is etched to obtain a base film with double conical channels;

[0024] S3. An aluminum metal layer is deposited on a base film with double conical pores to obtain the porous composite aluminum foil.

[0025] In a preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, the organic polymer film is made of polyethylene terephthalate (PET), polyimide (PI), polyethersulfone resin (PES), polyetherimide (PEI), polyethylene naphthalate (PEN), or polypropylene (PP).

[0026] In a preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, the heavy ions used in the heavy ion irradiation are elements with an atomic number greater than or equal to 36.

[0027] In a preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, the ion energy of the heavy ion irradiation is 1-30 MeV / u, and the flux of the heavy ion irradiation is 10. 4 -10 7 ions / cm 2 .

[0028] As a preferred embodiment of the preparation method of the porous composite aluminum foil of the present invention, an aluminum metal layer is deposited by magnetron sputtering or vacuum evaporation.

[0029] The application of the porous composite aluminum foil described in any of the above claims of the present invention in the preparation of battery electrodes.

[0030] A battery electrode sheet comprising the porous composite aluminum foil described in any one of the above claims.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0032] The porous composite aluminum foil of the present invention includes a base film and an aluminum metal layer deposited on the base film, wherein the base film is a thin film with biconical channels. The base film with biconical channels makes the overall porous composite aluminum foil lighter, and the biconical channels facilitate the deposition of the aluminum metal layer on the pore walls, enabling the aluminum metal layers on both sides of the base film thickness to connect and conduct. Simultaneously, the uniformly distributed channels can homogenize the current density, preventing pitting corrosion of the aluminum foil. Therefore, the overall porous composite aluminum foil has better conductivity, electrolyte wettability, cycle performance, and rate performance, and its conductivity is not affected by arbitrary cutting of the porous composite aluminum foil.

[0033] The method for preparing porous composite aluminum foil of the present invention involves treating a base film with heavy ion irradiation, followed by etching the base film to obtain a base film with biconical channels. An aluminum metal layer is then deposited on both sides of the base film's thickness and on the inner walls of the biconical channels to obtain the porous composite aluminum foil. The prepared porous composite aluminum foil possesses high conductivity, high strength, high flexibility, and ultra-thin properties, and can be mass-produced.

[0034] The porous composite aluminum foil of the present invention can be used as a current collector in the production of battery electrode sheets. The aluminum metal conductive layer deposited based on the double conical pore base film has a high specific surface area. The porous structure can increase the contact area with the electrode paste, thereby reducing the interface resistance, improving the charge and discharge rate performance, and having higher energy density and power density. Attached Figure Description

[0035] Figure 1a , Figure 1b and Figure 1c These are schematic diagrams of the conductive paths after cutting porous composite aluminum foil, commercial composite aluminum foil, and pure aluminum foil, respectively.

[0036] Figure 2 This is a schematic diagram of the preparation process of the porous composite aluminum foil of the present invention in a specific embodiment;

[0037] Figure 3a and Figure 3b SEM images of the surface and cross-section of the PET heavy ion microporous membrane prepared in Example 1 are shown respectively.

[0038] Figure 4a and Figure 4b SEM images of the porous composite aluminum foil prepared in Example 1 at different magnifications are shown.

[0039] Figure 5a and Figure 5b SEM images of the porous composite aluminum foil prepared in Example 1 at different magnifications;

[0040] Figure 6a and Figure 6b The figures show the EDS analysis results of the PET heavy ion microporous membrane prepared in Example 1 before and after sputtering the Al metal layer.

[0041] Figure 7a A schematic diagram of the apparatus for resistance testing of the porous composite aluminum foil in Example 1;

[0042] Figure 7b The graph shows the resistance test results of the porous composite aluminum foil of Example 1 at different sputtering times;

[0043] Figure 8a and Figure 8b The images show SEM images of the surface and cross-section of the PET heavy ion microporous membrane prepared in Example 2, respectively.

[0044] Figure 9a and Figure 9b The images show SEM images of the surface and cross-section of the porous composite aluminum foil prepared in Example 3, respectively.

[0045] Figure 10a and Figure 10b The images show SEM images of the surface and cross-section of the PI heavy ion microporous membrane prepared in Example 4, respectively.

[0046] Figure 11a and Figure 11b The images show SEM images of the surface and cross-section of the PES heavy ion microporous membrane prepared in Example 5, respectively.

[0047] Figure 12a and Figure 12b The images show SEM images of the surface and cross-section of the PET heavy ion microporous membrane prepared in Comparative Example 1, respectively.

[0048] Figure 13 The contact angle test results are shown for carbon-coated aluminum foil, porous composite aluminum foil of Example 1, composite aluminum foil, and pure aluminum foil.

[0049] Figure 14 The graph shows the cycle performance test results of carbon-coated aluminum foil, porous composite aluminum foil of Example 1, composite aluminum foil and pure aluminum foil at 1C rate. Detailed Implementation

[0050] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but the scope of protection and implementation of the present invention are not limited thereto. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0051] Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0052] It should be understood that the singular forms used in this invention, such as "a," include plural references unless otherwise specified. Furthermore, the terms "comprising," "containing," and "having" are open-ended rather than closed-ended, meaning they include the contents specified in this invention but do not exclude other aspects. In other words, the terms also include "consistently made of" or "composed of."

[0053] Furthermore, "and combinations thereof" in the specification refers to any combination of all the listed items. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0054] Unless otherwise specified, all technical and scientific terms used herein have the standard meaning in the field to which the claimed subject matter pertains. Where multiple definitions exist for a term, the definition herein shall prevail.

[0055] Unless otherwise specified, this invention employs standard nomenclature and standard laboratory procedures and techniques of analytical chemistry, organic synthetic chemistry and optics.

[0056] Without violating common sense in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0057] The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0058] The porous composite aluminum foil provided by the present invention includes a base film; the base film has a plurality of channels extending along the thickness direction, wherein the channels are double conical channels; and aluminum metal layers are deposited on both sides of the thickness of the base film and on the inner walls of the channels.

[0059] As a preferred embodiment of the porous composite aluminum foil of the present invention, the double conical channel includes a first conical channel whose diameter gradually decreases along a first thickness direction, and a second conical channel whose size gradually decreases along a second thickness direction opposite to the first thickness direction, wherein the first conical channel and the second conical channel are connected.

[0060] As a further preferred embodiment of the porous composite aluminum foil of the present invention, the first conical channel and the second conical channel are concentrically connected along the thickness direction.

[0061] As a further preferred embodiment of the porous composite aluminum foil of the present invention, the diameter of the large pore end of the first conical channel is 1-6 μm, and the diameter of the small pore end is 500 nm-3 μm.

[0062] As a further preferred embodiment of the porous composite aluminum foil of the present invention, the diameter of the large pore end of the second conical channel is 1-6 μm, and the diameter of the small pore end is 500 nm-3 μm.

[0063] As a preferred embodiment of the porous composite aluminum foil of the present invention, the double conical channel is an hourglass-shaped channel, with the conical ends (or small hole ends) of the two conical channels connected to each other in the thickness direction, while the bottom ends (or large hole ends) of the two conical channels are opposite to each other and distributed on both sides of the base film thickness direction.

[0064] Furthermore, as a preferred embodiment of the porous composite aluminum foil of the present invention, the diameter of the large pore end of the hourglass-shaped double conical channel is 1-6 μm, and the diameter of the small pore end is 500 nm-3 μm.

[0065] In a preferred embodiment of the porous composite aluminum foil of the present invention, the thickness of the base film is 6-30 μm.

[0066] In a preferred embodiment of the porous composite aluminum foil of the present invention, the pore density of the base film is 10. 4 -10 7 pcs / cm 2 .

[0067] In a preferred embodiment of the composite aluminum foil of the present invention, the base film is an organic film. More preferably, the base film is polyethylene terephthalate (PET), polyimide (PI), polyethersulfone resin (PES), polyetherimide (PEI), polyethylene naphthalate (PEN), or polypropylene (PP).

[0068] In a preferred embodiment of the porous composite aluminum foil of the present invention, the thickness of the aluminum metal layer is 100 nm-2 μm.

[0069] The porous composite aluminum foil of the present invention can effectively solve the problem that the two surfaces of commercial composite aluminum foil cannot conduct electricity, and the conductivity of the material is not affected by cutting the porous composite aluminum foil arbitrarily.

[0070] in, Figure 1a , 1b Figures 1 and 1c are schematic diagrams of the cross-sections of porous composite aluminum foil, commercial composite aluminum foil, and pure aluminum foil after cutting, respectively. Figure 1c It can be seen that pure aluminum foil retains good conductivity even after being cut, allowing electrons to freely conduct from one side to the other; Figure 1b It is known that commercial composite aluminum foil cannot conduct electricity after being cut, as the middle polymer insulating layer prevents electrons from being conducted to the other side; while... Figure 1a As can be seen, the porous composite aluminum foil of the present invention provides a conductive path that runs through the insulation layer, allowing electrons to still be conducted to the other side after cutting.

[0071] The porous composite aluminum foil of this invention exhibits excellent mechanical properties, electrochemical properties, and capacity retention. Compared to traditional composite aluminum foil, it offers better conductivity and is lighter, with a weight reduction of 55.47% and 15.78% compared to commercially available carbon-coated aluminum foil and composite aluminum foil, respectively. Several interconnected biconical channels provide more conductive pathways. Furthermore, the rough surface of the porous composite aluminum foil enhances adhesion to electrode pastes, resulting in lower interfacial resistance and reduced interfacial impedance. When applied to lithium-ion battery electrodes, it can effectively improve the rate performance of lithium-ion batteries.

[0072] The method for preparing porous composite aluminum foil provided by this invention is detailed in the following steps. Figure 2 As shown, it includes the following steps:

[0073] S1. The organic polymer film is subjected to heavy ion irradiation treatment, which causes the chemical bonds in the film along the heavy ion incident path to break, thereby obtaining an organic polymer film irradiated with heavy ions.

[0074] S2. The organic polymer film irradiated with heavy ions is etched. The etching solution reacts with the pores to break bonds, increasing the pore diameter. The track etching rate can be altered by controlling the concentration, temperature, and methanol ratio of the etching solution. (Etching rate along the ion incident direction) and bulk etching rate (Etching rate perpendicular to the ion incident direction), when the ratio of the two etching rates is a certain value, a base film with double conical channels can be obtained.

[0075] S3. An aluminum metal layer is deposited on a base film with double conical pores to obtain a porous composite aluminum foil.

[0076] In a preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, the organic polymer film is selected as an organic film. More preferably, the base film is selected as polyethylene terephthalate (PET), polyimide (PI), polyethersulfone resin (PES), polyetherimide (PEI), polyethylene naphthalate (PEN), or polypropylene (PP).

[0077] The method for preparing porous composite aluminum foil of the present invention utilizes heavy ion irradiation to prepare an organic thin film into a microporous membrane with uniform pore size and distribution. The pore density of the microporous membrane is controlled by adjusting the irradiation flux. Then, an etching process is performed to control the diameter and shape of the channels, thereby obtaining a microporous base film with biconical channels. Finally, aluminum metal is deposited on both sides of the base film and on the inner walls of the biconical channels. The biconical channels not only facilitate the deposition of aluminum atoms on the pore walls, allowing them to connect and form a conductive layer, but also increase the contact area with the electrode paste to reduce interfacial resistance and improve the rate performance of the battery. Furthermore, the uniformly distributed channels can homogenize the current density, preventing pitting corrosion of the aluminum foil.

[0078] In a preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, the heavy ions used in the heavy ion irradiation are ions of elements with an atomic number greater than or equal to 36. More preferably, the heavy ions used in the heavy ion irradiation include Xe ions, Bi ions, or Ta ions.

[0079] In a preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, the ion energy of the heavy ion irradiation is 1-30 MeV / u, and the flux of the heavy ion irradiation is 10. 4 -10 7 ions / cm 2 .

[0080] As a preferred embodiment of the method for preparing porous composite aluminum foil of the present invention, the double conical channel includes a first conical channel whose diameter gradually decreases along a first thickness direction, and a second conical channel whose size gradually decreases along a second thickness direction opposite to the first thickness direction, wherein the first conical channel and the second conical channel are connected.

[0081] As a further preferred embodiment of the method for preparing porous composite aluminum foil of the present invention, the first conical channel and the second conical channel are concentrically connected along the thickness direction.

[0082] As a further preferred embodiment of the method for preparing porous composite aluminum foil of the present invention, the diameter of the large pore end of the first conical channel is 1-6 μm, and the diameter of the small pore end is 500 nm-3 μm.

[0083] As a further preferred embodiment of the method for preparing porous composite aluminum foil of the present invention, the diameter of the large pore end of the second conical channel is 1-6 μm, and the diameter of the small pore end is 500 nm-3 μm.

[0084] In a preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, the thickness of the base film is 6-30 μm.

[0085] In a preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, the pore density of the base film is 10. 4-10 7 pcs / cm 2 .

[0086] In a preferred embodiment of the method for preparing porous composite aluminum foil of the present invention, in S2, the organic polymer film irradiated with heavy ions is etched with an etching solution under constant temperature conditions in a water bath, then taken out, cleaned with deionized water and dried by blowing air, and then the S3 operation is performed.

[0087] As a further preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, when the base film is polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), the etching solution is a mixed solution of sodium hydroxide and anhydrous methanol, wherein the concentration of sodium hydroxide is 1 M-15 M, and the volume ratio of sodium hydroxide to anhydrous methanol is 1:0.5-1:4. Furthermore, the etching temperature is 30-80 °C, and the etching time is 10-60 min.

[0088] As a further preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, when the base film is polyimide (PI) or polyetherimide (PEI), the etching solution is a sodium hypochlorite solution, wherein the mass percentage content of available chlorine is 5-15%. Furthermore, the etching temperature is 30-80 °C, and the etching time is 10-120 min.

[0089] In a further preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, when the base film is polyethersulfone resin (PES) or polypropylene (PP), the etching solution is a chromic acid solution with a molar concentration of 1-15 mol / L. Furthermore, the etching temperature is 30-80°C, and the etching time is 10-120 min.

[0090] In a preferred embodiment of the method for preparing the porous composite aluminum foil of the present invention, an aluminum metal layer is deposited by magnetron sputtering or vacuum evaporation. In some preferred embodiments, a Quorum Q150TS magnetron sputtering instrument is used; further, the sputtering current is 30-150 mA and the sputtering time is 1-12 h.

[0091] This invention provides the application of the aforementioned porous composite aluminum foil, specifically in the preparation of battery electrodes, such as in the preparation of lithium-ion battery electrodes, but not limited to lithium-ion battery electrodes.

[0092] The battery electrode provided by this invention contains the porous composite aluminum foil described in any of the above-mentioned claims. The battery electrode of this invention can be a lithium-ion battery electrode, but is not limited to lithium-ion battery electrodes, enabling the corresponding lithium-ion battery to have higher energy density and power density, making it more suitable for energy storage fields such as new energy vehicles.

[0093] Example 1

[0094] The preparation steps of the porous composite aluminum foil with double conical channels in this embodiment are as follows:

[0095] (1) Using a heavy ion accelerator with an energy of 19.5 MeV / u 129 Xe ions were used to vertically and uniformly irradiate a 19 μm thick PET film in a vacuum environment at an irradiation flux of 1.5 × 10⁻⁶. 6 ions / cm 2 .

[0096] (2) The irradiated PET film was placed in a mixed etching solution (a mixed solution of sodium hydroxide and anhydrous methanol, with a NaOH concentration of 15 M and a volume ratio of sodium hydroxide to anhydrous methanol of 1:3) for etching at a temperature of 30 °C for 30 mins. After etching, it was first cleaned with deionized water and then dried in a forced-air drying oven to obtain a PET heavy ion microporous membrane with double conical channels.

[0097] The surface and cross-sectional SEM images of the obtained PET heavy ion microporous membrane are shown below. Figure 3a and Figure 3b As shown, from Figure 3a and Figure 3b It can be seen that the pores of the PET heavy ion microporous membrane are hourglass-shaped double conical pores. Each single pore of the double conical pore is composed of two conical pores with their cone apexes facing each other towards the inside of the base membrane and connected to each other. The pore diameter of the conical pores is uniform, with the large pore end located on the surface of the base membrane and the small pore end located inside the base membrane. The pore diameter of the large pore end is 5±0.5 μm and the pore diameter of the small pore end is 2.5±0.5 μm.

[0098] (3) The etched base film is placed in a magnetron sputtering instrument to deposit an aluminum metal layer with a thickness of 1 μm on the surface of the base film. The sputtering current is 100 mA and the sputtering time is 6 h to obtain the Al@PET heavy ion microporous membrane composite aluminum foil of this embodiment.

[0099] The surface SEM images of the Al@PET heavy ion microporous membrane composite aluminum foil prepared in this embodiment at different magnifications are shown below. Figure 4a (900 times) and Figure 4b As shown in the image (20,000x magnification), and the cross-sectional SEM images at different magnifications are respectively shown in the image. Figure 5a (10,000 times) and Figure 5b As shown in the 40,000x magnification, the surface SEM and cross-sectional SEM of the Al@PET heavy ion microporous membrane composite aluminum foil show that the magnetron sputtered Al metal layer has a uniform thickness, a smooth surface, and a strong bond with the substrate.

[0100] Elemental analysis was performed on the Al@PET heavy ion microporous membrane composite aluminum foil prepared in this embodiment. The EDS (energy dispersive spectroscopy) results are as follows: Figure 6a and Figure 6b As shown, the results indicate that the Al element is uniformly distributed on the surface and inside the pores of the composite aluminum foil prepared in this embodiment, which shows that an aluminum metal layer was successfully deposited on the surface of the base film and inside the pores.

[0101] The resistance of the Al@PET heavy ion microporous membrane composite aluminum foil prepared in this embodiment was tested, and the test device diagram is shown below. Figure 7a As shown, this was done to test the pore resistance of the porous composite aluminum foil. (i.e., electrons are conducted only through the inner wall of the channel) and volume resistance (That is, electrons are conducted through the inner wall of the channel and the edge of the thin film). Before sputtering, a circular iron ring is placed in the center of the thin film to block the flow. The resulting porous composite aluminum foil has an insulating portion corresponding to the portion blocked by the circular iron ring, allowing for separate measurement of the two types of resistance. The resistance test results under different sputtering durations are as follows: Figure 7b As shown, the resistance of the sputtered porous composite aluminum foil was measured. With increasing sputtering time, the aluminum metal layer on the pore walls continuously thickened, and the pore resistance increased. As the resistance gradually decreases from 50 Ω to 0.5 Ω, the volume resistance... The conductivity remained in the range of several hundred milliohms, indicating that the presence of the aluminum metal layer on the hole wall can improve the conductivity between the upper and lower sides of the composite aluminum foil, thereby improving the overall conductivity of the composite aluminum foil and ensuring that the composite aluminum foil can still achieve high conductivity after being arbitrarily cut without the need for edge transfer welding process. Example 2

[0102] The preparation steps of the porous composite aluminum foil with double conical channels in this embodiment are as follows:

[0103] (1) Using a heavy ion accelerator with an energy of 19.5 MeV / u 129 Xe ions were used to vertically and uniformly irradiate a 30 μm thick PET film at an irradiation flux of 1 × 10⁻⁶. 4 ions / cm 2 .

[0104] (2) The irradiated PET film was placed in a mixed etching solution (a mixed solution of sodium hydroxide and anhydrous methanol, with a NaOH concentration of 5 M and a volume ratio of sodium hydroxide to anhydrous methanol of 1:4) for etching at a temperature of 80 °C for 50 mins. After etching, it was first cleaned with deionized water and then dried in a forced-air drying oven to obtain a heavy ion microporous membrane base film with double conical channels, wherein the pore diameter at the large end of the double conical channels is 6 ± 0.5 μm and the pore diameter at the small end is 3 ± 0.5 μm.

[0105] The surface and cross-sectional SEM images of the obtained PET heavy ion microporous membrane are shown below. Figure 8a and Figure 8b As shown, by Figure 8a and Figure 8b It can be seen that the obtained PET heavy ion microporous membrane has a double conical pore structure with uniform pore size. The large pore end is located on the surface of the base membrane, while the small pore end is located inside the base membrane. The pore size of the large pore end is 6±0.5 μm, and that of the small pore end is 3±0.5 μm.

[0106] (3) The etched base film is placed in a magnetron sputtering instrument to deposit an aluminum metal layer with a thickness of 2 μm on the surface of the base film. The sputtering current is 50 mA and the sputtering time is 12 h to obtain the Al@PET heavy ion microporous membrane composite aluminum foil of this embodiment. Example 3

[0107] The preparation steps of the porous composite aluminum foil with double conical channels in this embodiment are as follows:

[0108] (1) Using a heavy ion accelerator with an energy of 5.98 MeV / u 129 Xe was used to vertically and uniformly irradiate a 6 μm thick PET film in a vacuum environment with an irradiation flux of 1 × 10⁻⁶. 7 ions / cm 2 .

[0109] (2) The irradiated PET film was placed in a mixed etching solution (a mixed solution of sodium hydroxide and anhydrous methanol, with a NaOH concentration of 1 M and a volume ratio of sodium hydroxide to anhydrous methanol of 1:1) for etching. The etching temperature was 50 °C and the etching time was 10 mins. After etching, the film was first cleaned with deionized water and then dried in a forced-air drying oven to obtain a heavy ion microporous membrane base film with double conical channels. The pore diameter at the large end of the double conical channels was about 2 μm and the pore diameter at the small end was about 0.5 μm.

[0110] (3) The etched base film is placed in a magnetron sputtering instrument to deposit an aluminum metal layer with a thickness of 100 nm on the surface of the base film. The sputtering current is 150 mA and the sputtering time is 2 h to obtain the Al@PET heavy ion microporous membrane composite aluminum foil of this embodiment.

[0111] The surface and cross-sectional SEM images of the Al@PET heavy ion microporous membrane composite aluminum foil prepared in this embodiment are shown below. Figure 9a and Figure 9b As shown, by Figure 9a and Figure 9bIt can be seen that in the prepared Al@PET heavy ion microporous membrane composite aluminum foil, the pores of the base film are biconical channels with uniform pore size. The large pore ends are located on the surface of the base film, while the small pore ends are located inside the base film. The pore size of the large pore ends is 2±0.5 μm, and that of the small pore ends is 0.5±0.1 μm. Furthermore, from... Figure 9a and Figure 9b It can be seen that the Al metal coating sputtered by magnetron sputtering has a uniform thickness, a smooth surface, and a strong bond with the substrate. Example 4

[0112] The preparation steps of the porous composite aluminum foil with double conical channels in this embodiment are as follows:

[0113] (1) Using a heavy ion accelerator with an energy of 19.5 MeV / u 129 Xe was used to vertically and uniformly irradiate a 12.5 μm thick PI film in a vacuum environment with an irradiation flux of 5 × 10⁻⁶. 6 ions / cm 2 .

[0114] (2) The irradiated PI film was placed in a sodium hypochlorite solution with an effective chlorine content of 8% and etched at a constant temperature of 70°C for 1 h in a water bath. After etching, it was first cleaned with deionized water and then dried in a forced-air drying oven to obtain a PI heavy ion microporous membrane base film with double conical channels, wherein the pore diameter at the large end of the double conical channels is 4±0.5 μm and the pore diameter at the small end is 1±0.2 μm.

[0115] The surface and cross-sectional SEM images of the obtained PI heavy ion microporous membrane are shown below. Figure 10a and Figure 10b As shown, by Figure 10a and Figure 10b It can be seen that the obtained PET heavy ion microporous membrane has a double conical pore structure with uniform pore size. The macropore end is located on the surface of the base membrane, while the micropore end is located inside the base membrane. The macropore end has a pore size of 4±0.5 μm, and the micropore end has a pore size of 1±0.2 μm.

[0116] (3) The etched base film is placed in a magnetron sputtering instrument to deposit an aluminum metal layer with a thickness of 1 μm on the surface of the base film. The sputtering current is 150 mA and the sputtering time is 4 h to obtain the Al@PI heavy ion microporous membrane composite aluminum foil of this embodiment. Example 5

[0117] The preparation steps of the porous composite aluminum foil with double conical channels in this embodiment are as follows:

[0118] (1) Using the energy of 25 MeV / u provided by the heavy ion accelerator 129 Xe was used to vertically and uniformly irradiate a 25 μm thick PES film in a vacuum environment with an irradiation flux of 1 × 10⁻⁶.5 ions / cm 2 .

[0119] (2) The irradiated PES film was placed in a 10 M chromic acid solution and etched at a constant temperature of 80°C for 2 h in a water bath. After etching, it was first cleaned with deionized water and then dried in a forced-air drying oven to obtain a PES heavy ion microporous membrane base film with double conical channels, wherein the pore diameter at the large end of the double conical channels is 3±0.5 μm and the pore diameter at the small end is 1±0.2 μm.

[0120] The surface and cross-sectional SEM images of the obtained PES heavy ion microporous membrane are shown below. Figure 11a and Figure 11b As shown, by Figure 11a and Figure 11b It can be seen that the obtained PET heavy ion microporous membrane has a double conical pore structure with uniform pore size. The large pore end is located on the surface of the base membrane, while the small pore end is located inside the base membrane. The pore size of the large pore end is 3±0.5 μm, and that of the small pore end is 1±0.2 μm.

[0121] (3) The etched base film is placed in a magnetron sputtering instrument to deposit an aluminum metal layer with a thickness of 500 nm on the surface of the base film. The sputtering current is 100 mA and the sputtering time is 4 h to obtain the Al@PES heavy ion microporous membrane composite aluminum foil of this embodiment. Comparative Example 1

[0122] The preparation steps of the porous composite aluminum foil with cylindrical through holes in this comparative example are as follows:

[0123] (1) Using a heavy ion accelerator with an energy of 19.5 MeV / u 129 Xe ions were used to vertically and uniformly irradiate a 19 μm thick PET film in a vacuum environment at an irradiation flux of 1.5 × 10⁻⁶. 6 ions / cm 2 .

[0124] (2) The irradiated PET film was sensitized by using a UV lamp for 2 hours; then it was etched in a mixed etching solution (a mixed solution of sodium hydroxide and anhydrous methanol, with a NaOH concentration of 15 M and a volume ratio of sodium hydroxide to anhydrous methanol of 1:3), with an etching temperature of 30 ℃ and an etching time of 30 mins. After etching, it was first cleaned with deionized water and then dried in a forced-air drying oven to obtain a PET through-hole heavy ion microporous membrane with a pore size of 5±0.5 μm.

[0125] The surface and cross-sectional SEM images of the obtained PET through-hole heavy ion microporous membrane are shown below. Figure 12a and Figure 12b As shown, from Figure 12a and Figure 12b It can be seen that the pores of the PET through-hole heavy ion microporous membrane are through-holes with a pore size of 5±0.5 μm.

[0126] (3) The etched base film is placed in a magnetron sputtering instrument to deposit an aluminum metal layer with a thickness of 1 μm on the surface of the base film, wherein the sputtering current is 100 mA and the sputtering time is 6 h.

[0127] Resistance measurements were performed on the cylindrical straight-hole porous composite aluminum foil prepared in this comparative example. The results showed that the resistance of the prepared cylindrical straight-hole porous composite aluminum foil was infinite and non-conductive. In contrast, the resistance of the double-conical channel porous composite aluminum foil of Example 1 under the same preparation conditions was 0.5 Ω, which proves that the conical channel is more conducive to the deposition of metal in the channel wall.

[0128] Comparative Test

[0129] Electrochemical performance was measured using different aluminum foils as test objects.

[0130] Test subject:

[0131] (1) The composite aluminum foil purchased from the market has a total thickness of 10 μm, of which the base film thickness is 8 μm, the upper and lower aluminum metal layers are each 1 μm, and the base film does not have through holes.

[0132] (2) Commercially available carbon-coated aluminum foil, wherein the total thickness of the aluminum foil plus the carbon layer is 16 μm.

[0133] (3) Porous composite aluminum foil prepared in Example 1.

[0134] (3) Pure aluminum foil purchased from the market, wherein the aluminum foil thickness is 16 μm.

[0135] 1. Contact Angle Test

[0136] The contact angle of carbon-coated aluminum foil, the porous composite aluminum foil of Example 1, the composite aluminum foil, and the pure aluminum foil were tested with pure water. The test results are as follows: Figure 13 As shown, the contact angle of the commercially available carbon-coated aluminum foil is 72.38°, the contact angle of the composite aluminum foil is 91.35°, the contact angle of the pure aluminum foil is 67.51°, and the contact angle of the porous composite aluminum foil prepared in Example 1 is 53.93°.

[0137] Test results show that the porous composite aluminum foil prepared in Example 1 has a smaller contact angle, higher electrolyte wettability, and lower interfacial impedance compared to composite aluminum foil, which is beneficial for electron transport and high-rate cycling.

[0138] 2. Cyclic performance test

[0139] Carbon-coated aluminum foil, porous composite aluminum foil from Example 1, composite aluminum foil, and pure aluminum foil were assembled into CR2032 coin cells, and their electrochemical performance was tested. First, a positive electrode slurry (prepared by dissolving lithium iron phosphate (LFP), activated carbon (CP), and polytetrafluoroethylene (PVDF) in N-methyl-2-pyrrolidone (NMP) at a mass ratio of 8:1:1) was coated onto the aluminum foil. Then, Celgard 2500 was used as the separator, lithium metal was used as the negative electrode, and the cells were assembled in an argon-atmospheric glove box. The electrolyte was a 1 M LiPF6 solution of ethylene carbonate and dimethyl carbonate (volume ratio 1:1).

[0140] Cyclic performance test results at 1C rate are as follows: Figure 14 As shown, the coin cell corresponding to the porous composite aluminum foil in Example 1 exhibited excellent cycle stability under 1C charge-discharge conditions, with a capacity retention of 97.48% after 250 cycles, which is higher than that of pure aluminum foil (68.52%) and commercially carbon-coated aluminum foil (88.17%). Under the same conditions, the composite aluminum foil battery experienced an open circuit failure due to poor edge conductivity and could not function properly.

[0141] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, this specification does not describe all possible combinations of the technical features in the above embodiments. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. Furthermore, the above embodiments only illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent.

[0142] It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of this invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A porous composite aluminum foil, characterized in that, The substrate includes a base film; the base film has a plurality of channels extending along the thickness direction, the channels being hourglass-shaped double-conical channels; aluminum metal layers are deposited on both sides of the base film and on the inner walls of the channels; The channel resistance is 0.5Ω; The contact angle of the porous composite aluminum foil is 53.93°; The preparation method of porous composite aluminum foil includes the following steps: (1) Utilizing the energy of 19.5 MeV / u provided by the heavy ion accelerator 129 Xe ions were used to vertically and uniformly irradiate a 19 μm thick PET film in a vacuum environment at an irradiation flux of 1.5 × 10⁻⁶. 6 ions / cm 2 ; (2) The irradiated PET film was placed in a mixed etching solution for etching at a temperature of 30°C for 30 mins. After etching, it was first cleaned with deionized water and then dried in a forced-air drying oven to obtain a PET heavy ion microporous membrane with double conical channels. The mixed etching solution is a mixture of sodium hydroxide and anhydrous methanol, with a NaOH concentration of 15M and a volume ratio of sodium hydroxide to anhydrous methanol of 1:

3. The pores of the PET heavy ion microporous membrane are hourglass-shaped double conical pores. Each pore consists of two conical pores with their apexes facing each other towards the inside of the base membrane and connected to each other. The pore diameter of the conical pores is uniform. The large pore end is located on the surface of the base membrane and the small pore end is located inside the base membrane. The pore diameter of the large pore end is 5±0.5μm and the pore diameter of the small pore end is 2.5±0.5μm. (3) The etched base film is placed in a magnetron sputtering instrument to deposit an aluminum metal layer with a thickness of 1 μm on the surface of the base film, wherein the sputtering current is 100 mA and the sputtering time is 6 h, to obtain the porous composite aluminum foil.

2. The porous composite aluminum foil according to claim 1, characterized in that, The thickness of the base film is 6-30 μm.

3. The porous composite aluminum foil according to claim 1, characterized in that, The pore density of the base film is 10. 4 -10 7 pcs / cm 2 .

4. A method for preparing a porous composite aluminum foil, characterized in that, Includes the following steps: (1) Utilizing the energy of 19.5 MeV / u provided by the heavy ion accelerator 129 Xe ions were used to vertically and uniformly irradiate a 19 μm thick PET film in a vacuum environment at an irradiation flux of 1.5 × 10⁻⁶. 6 ions / cm 2 ; (2) The irradiated PET film was placed in a mixed etching solution for etching at a temperature of 30°C for 30 mins. After etching, it was first cleaned with deionized water and then dried in a forced-air drying oven to obtain a PET heavy ion microporous membrane with double conical channels. The mixed etching solution is a mixture of sodium hydroxide and anhydrous methanol, with a NaOH concentration of 15M and a volume ratio of sodium hydroxide to anhydrous methanol of 1:

3. The pores of the PET heavy ion microporous membrane are hourglass-shaped double conical pores. Each pore consists of two conical pores with their apexes facing each other towards the inside of the base membrane and connected to each other. The pore diameter of the conical pores is uniform. The large pore end is located on the surface of the base membrane and the small pore end is located inside the base membrane. The pore diameter of the large pore end is 5±0.5μm and the pore diameter of the small pore end is 2.5±0.5μm. (3) The etched base film is placed in a magnetron sputtering instrument to deposit an aluminum metal layer with a thickness of 1 μm on the surface of the base film, wherein the sputtering current is 100 mA and the sputtering time is 6 h, to obtain the porous composite aluminum foil.

5. The application of the porous composite aluminum foil according to any one of claims 1-3 in the preparation of battery electrodes.

6. A battery electrode, characterized in that, Contains the porous composite aluminum foil according to any one of claims 1-3.

Images