A composite aluminum material and its preparation method, a battery negative electrode material, and a battery.

Abstract

This invention discloses a composite aluminum material and its preparation method, a battery anode material, and a battery. The composite aluminum material includes an aluminum sheet and a twinned metal material coated on the upper and lower surfaces of the aluminum sheet. The sheet-like structure design enables surface contact between the aluminum materials, reducing the contact resistance between the materials. The twinned metal coating acts as an oxygen barrier, preventing the aluminum material from rapidly oxidizing in air, and also possesses good ionic and electron conduction capabilities, facilitating the coupling of electrons and ions in the aluminum anode material. Ultimately, the above structural design effectively reduces the electrochemical polarization problem of the aluminum anode material in small sizes, helping to activate its electrochemical performance. In addition, this invention also proposes a bottom-up method for preparing composite aluminum sheets with twinned metal coatings, using physical vapor deposition to deposit an aluminum metal film on a carbon-treated polymer film substrate, solving the problem of continuous oxidation of aluminum sheets during bottom-up preparation.

Description

Technical Field

[0001] This invention relates to the field of energy storage materials technology, and in particular to a composite aluminum material and its preparation method, a battery negative electrode material, and a battery. Background Technology

[0002] Lithium-ion batteries are widely used in consumer electronics and energy storage. With technological advancements, the capacity requirements for lithium-ion batteries are increasing. Currently, graphite anode materials, the most widely used in lithium-ion batteries, are gradually approaching their theoretical specific capacity (372 mAh g⁻¹). -1 Therefore, developing novel, low-cost, high-capacity anode materials is imperative. Aluminum metal anodes possess a high theoretical specific capacity (993 mAh g⁻¹). -1 Its high energy density makes it a potential next-generation lithium-ion battery anode material.

[0003] In related technologies, due to the high reactivity of aluminum, it readily forms an electronically insulating oxide layer in air, and the volume ratio of the oxide layer increases with the decrease in aluminum size. During the miniaturization of aluminum, the reduction in aluminum size is accompanied by an increase in the volume ratio of aluminum oxide on its surface. This leads to significant ohmic polarization when small-sized aluminum materials are used as anode materials in lithium-ion batteries. The aluminum anode cannot form effective electron-ion coupling, resulting in poor electrochemical performance and drawbacks such as large polarization, an indistinct charge-discharge plateau, and low actual specific capacity. Furthermore, the high reactivity of aluminum dictates that its miniaturization is primarily achieved through top-down fabrication methods, such as mechanical milling, evaporation and condensation, and laser ablation. The micron-sized and smaller aluminum powders prepared by these methods are often granular, with point contact being the primary form of contact between aluminum particles. This point-contact conductivity results in high contact resistance between aluminum particles, leading to severe polarization when small-sized aluminum is used as anode material due to the large ohmic impedance.

[0004] Therefore, solving the severe electrochemical polarization problem of aluminum anode materials in small sizes, reducing the contact resistance between materials, and improving their electrochemical performance are of great significance. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a composite aluminum material and its preparation method, a battery anode material, and a battery, aiming to solve the problems of severe electrochemical polarization, high contact resistance between materials, and insufficient electrochemical performance of current aluminum anode materials in small sizes.

[0006] In a first aspect, the present invention provides a composite aluminum material comprising an aluminum sheet and a twinned metal material; wherein the twinned metal material coats the upper and lower surfaces of the aluminum sheet to form an upper twinned metal coating layer and a lower twinned metal coating layer.

[0007] The composite aluminum material according to embodiments of the present invention has at least the following beneficial effects: The present invention proposes a sheet-like composite aluminum material with twinned metal cladding, the structure of which consists of three parts: an upper twinned metal cladding layer, an aluminum sheet, and a lower twinned metal cladding layer. The aluminum sheet is located between the upper and lower twinned metal cladding layers, forming a "sandwich" structure. Figure 1 As shown, the aluminum sheet structure in the middle (i.e., "aluminum sheet" or "sheet aluminum") has a size in the micrometer range or smaller, which can well accommodate the volume expansion problem that occurs when aluminum is used as a negative electrode material. The twin boundaries present in the twin metal provide a path for ion transport, realizing dual electron-ion conduction. The twin metal coats the upper and lower surfaces of the aluminum sheet, playing the role of oxygen isolation and dual electron-ion conduction. On the one hand, when the sheet-like aluminum material is used as a negative electrode material, the contact between the sheets is mainly in the form of surface contact, which greatly reduces the contact resistance between materials, significantly improving the conductivity of small-sized aluminum materials and greatly reducing the polarization problem caused by the material when used as a negative electrode material. On the other hand, the twin metal has good dual electron-ion conduction capability. The design of the twin metal coating can not only play a good role in oxygen isolation, preventing the aluminum material from rapidly oxidizing in the air, but also ensure that electron-ion transport is not affected, which helps the coupling of electrons and ions in the aluminum material. Therefore, the sheet-like composite aluminum material with twinned metal coating design can greatly reduce the polarization problem caused by the ohmic impedance between aluminum materials when aluminum materials are used as negative electrode materials, and activate its electrochemical performance.

[0008] In some embodiments of the present invention, the aluminum sheet comprises aluminum microsheets or aluminum nanosheets, the thickness of which is adjustable and the sheet diameter is much larger than the thickness. The size of the aluminum sheet is at or below the micrometer level, which can well accommodate the volume expansion problem that occurs when aluminum is used as a negative electrode material. When the sheet-like aluminum nanosheets or aluminum microsheets are used as negative electrode materials, the contact between the sheets is mainly in the form of surface contact, which greatly reduces the contact resistance between materials, significantly improving the conductivity of small-sized aluminum materials and greatly reducing polarization problems caused by the material when used as a negative electrode material.

[0009] In some embodiments of the present invention, the thickness of the aluminum sheet is 1 nm to 100 μm.

[0010] In some preferred embodiments of the present invention, the thickness of the aluminum sheet is 100nm to 500nm, for example, it can be 100nm, 200nm, 300nm, 400nm, or 500nm.

[0011] In some preferred embodiments of the present invention, the thickness of the aluminum sheet is approximately 500 nm.

[0012] In some embodiments of the present invention, the diameter of the aluminum sheet is 1 μm to 200 μm.

[0013] In some preferred embodiments of the present invention, the aluminum sheet has a diameter of 10μm to 100μm, for example, it can be 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, or 100μm.

[0014] In some preferred embodiments of the present invention, the aluminum sheet has a diameter of approximately 10 μm.

[0015] In some embodiments of the present invention, the twinned metal material coating refers to coating the upper and lower surfaces of an aluminum sheet with a twinned metal material to form a "sandwich" structure, with a coating thickness less than 1 / 10 of the aluminum sheet. The twinned metal material refers to a metal material with a twinned structure. The twin boundaries present in the twinned metal provide pathways for ion transport, achieving dual electron-ion conduction. The twinned metal coating on the upper and lower surfaces of the aluminum sheet, with a thickness less than 1 / 10 of the aluminum sheet, serves to isolate oxygen and provide dual electron-ion conduction.

[0016] In some embodiments of the present invention, the twinned metal material is selected from single-element materials composed of single elements in Groups I to VII, Group VIII, Group III, and Group IV, or alloys or composite materials composed of multiple elements; however, it is not limited thereto, and any metal material with a twinned structure can be used.

[0017] In some preferred embodiments of the present invention, the twinned metal material is selected from a single element composed of copper, titanium, zinc, nickel, and chromium, or an alloy or composite material composed of multiple elements.

[0018] In some more preferred embodiments of the present invention, the twinned metal material is selected from titanium, zinc, nickel, chromium, zinc-titanium alloy, and zinc-copper alloy.

[0019] In some embodiments of the present invention, the thickness of the upper twin metal coating layer is 1 nm to 300 nm.

[0020] In some preferred embodiments of the present invention, the thickness of the upper twin metal coating layer is 1 nm to 50 nm, for example, it can be 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm.

[0021] In some preferred embodiments of the present invention, the thickness of the upper twin metal cladding layer is approximately 50 nm.

[0022] In some embodiments of the present invention, the thickness of the lower twin metal cladding layer is 1 nm to 300 nm.

[0023] In some preferred embodiments of the present invention, the thickness of the lower twin metal cladding layer is 1 nm to 50 nm, for example, it can be 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm.

[0024] In some preferred embodiments of the present invention, the thickness of the lower twin metal cladding layer is approximately 50 nm.

[0025] In some embodiments of the present invention, the thickness of the composite aluminum material is 100 nm to 100 μm. The composite aluminum material is of nanosheet, microsheet, or submicron sheet thickness. The thickness of the composite aluminum material is related to the thickness of the aluminum sheet and the thickness of the twinned metal cladding layer. For example, if the aluminum sheet thickness is 500 nm, and the thicknesses of both the upper and lower twinned metal cladding layers are 50 nm, then the thickness of the composite aluminum material is 600 nm. Further details will not be elaborated here.

[0026] A second aspect of the present invention provides a method for preparing a composite aluminum material, comprising the steps of:

[0027] S1. Provide a polymer film substrate and clean the polymer film substrate;

[0028] S2. Perform carbon pretreatment on the cleaned polymer film substrate to obtain a carbon-coated polymer film substrate.

[0029] S3. Using physical vapor deposition technology, a lower twin metal film layer, an aluminum metal film layer, and an upper twin metal film layer are successively deposited on the surface of the carbon-plated polymer film substrate to form a sandwich structure composite aluminum metal film.

[0030] S4. After the carbon-plated polymer film substrate on which the composite aluminum metal film has been deposited is left to stand, it is placed in an organic solvent for ultrasonic treatment to peel off the carbon-plated polymer film. Then the organic solvent is removed to obtain the composite aluminum material.

[0031] The method for preparing composite aluminum materials according to embodiments of the present invention has at least the following beneficial effects: The high reactivity of aluminum makes it difficult to prepare small-sized aluminum materials using a bottom-up approach; traditional top-down preparation methods (such as mechanical milling, evaporation and condensation, and laser ablation) result in significant material waste and cannot control the morphology of the material from an atomic or molecular perspective, leading to poor particle size and morphological consistency. Furthermore, it is difficult to protect the material during preparation, and the prepared aluminum nanomaterials typically have a thick oxide layer, resulting in low electronic conductivity. Based on this, the present invention proposes a bottom-up preparation method for preparing small-sized aluminum materials with a sheet-like structure (i.e., the "aluminum sheet"): Aluminum metal films are deposited on a carbon-plated polymer film substrate using physical vapor deposition (PVD). The carbon plating of the polymer substrate facilitates the peeling of the aluminum metal film. After simple ultrasonic treatment, aluminum sheets with adjustable thickness can be prepared from the bottom up. PVD provides a high-vacuum environment for the growth of the aluminum sheet, solving the problem of continuous oxidation that occurs during bottom-up preparation. The carbon-coated polymer film provides a good substrate for the growth and collection of aluminum sheets: it not only has a low coefficient of thermal expansion and excellent thermal stability, which can withstand the high temperature of aluminum metal during physical vapor deposition, but also facilitates the peeling of the prepared aluminum metal film, which is convenient for ultrasonic formation of aluminum sheets after peeling.

[0032] In some embodiments of the present invention, the physical vapor deposition technology includes vacuum evaporation coating technology, vacuum magnetron sputtering technology, and ion plating technology, but is not limited thereto.

[0033] In some embodiments of the present invention, the polymer film substrate includes, but is not limited to, polyimide (PI) film, carbonate (PC) film, polyethylene terephthalate (PET) film, polypropylene (PP) film, polyethylene (PE) film, polyvinyl chloride (PVC) film, polytetrafluoroethylene (PTFE) film, polystyrene (PS) film, and polyvinylidene fluoride (PVDF) film.

[0034] In some preferred embodiments of the present invention, the polymer film substrate is selected from pyromellitic polyimide film.

[0035] In some embodiments of the present invention, the thickness of the polymer film substrate is 3 μm to 100 μm.

[0036] In some preferred embodiments of the present invention, the thickness of the polymer film substrate is 10 μm to 25 μm.

[0037] In some preferred embodiments of the present invention, the thickness of the polymer film substrate is approximately 25 μm.

[0038] In some embodiments of the present invention, in step S1, the polymer film substrate is ultrasonically cleaned using an organic solution, including but not limited to methanol, ethanol, and acetone.

[0039] In some embodiments of the present invention, in step S2, a carbon-plated pretreatment is performed on the cleaned polymer film substrate using physical vapor deposition (PVD) technology to obtain a carbon-plated polymer film substrate. The PVD technology includes, but is not limited to, vacuum evaporation deposition, vacuum magnetron sputtering, and ion plating.

[0040] In some embodiments of the present invention, the carbon plating pretreatment includes depositing an amorphous carbon layer on the surface of the polymer film substrate, wherein the thickness of the amorphous carbon layer is 1 nm to 50 nm.

[0041] In some preferred embodiments of the present invention, the thickness of the amorphous carbon layer is 10 nm to 20 nm.

[0042] In some preferred embodiments of the present invention, the thickness of the amorphous carbon layer is about 10 nm.

[0043] In some embodiments of the present invention, in step S3, physical vapor deposition (PVD) is employed. By controlling process parameters, a twinned metal thin film layer (lower twinned metal thin film layer) is first deposited on the surface of the carbon-plated polymer thin film substrate, followed by the deposition of an aluminum metal thin film layer, and finally, another twinned metal thin film layer (upper twinned metal thin film layer) is deposited, ultimately forming a composite aluminum metal thin film with a sandwich structure and twinned metal coating. The PVD technique includes, but is not limited to, vacuum evaporation deposition, vacuum magnetron sputtering, and ion plating.

[0044] In some embodiments of the present invention, the twinned metal is achieved by controlling the process parameters and deposition time. For example, in a specific embodiment of the present invention, a composite aluminum submicron sheet with a twinned copper metal coating layer is prepared by magnetron sputtering technology. The thickness of the twinned copper metal coating layer is 50 nm, and the corresponding thickness of the aluminum metal layer is 500 nm. The specific preparation process is as follows: (1) The polyimide film is ultrasonically cleaned with 95% ethanol, dried thoroughly, and then pasted onto the circular roller of the magnetron sputtering instrument. Then, the vacuum coating chamber of the magnetron sputtering instrument is heated to 200°C, and then the pressure is evacuated to 10. -4Pa. (2) Select a carbon target with a purity of 99.99% and a deposition power of 1KW. Introduce argon gas with a flow rate of 300sccm into the vacuum coating chamber to perform carbon pretreatment on the polyimide film. The coating steps are as follows: turn on the bias voltage of 50V, deposit for 5 minutes to obtain the polyimide film after carbon pretreatment, and then cool to room temperature. (3) Select a copper target and an aluminum target with a purity of 99.99%. The deposition power of copper is 1KW and the deposition power of aluminum is 2KW. Introduce argon gas with a flow rate of 300sccm into the vacuum coating chamber to heat the vacuum coating chamber of the magnetron sputtering instrument to 200℃, and then evacuate to a pressure of 10 -4 Pa. The coating steps are as follows: Under a bias voltage of 50V, the copper target is first turned on and deposited on the interface-modified polyimide film for 2 minutes. Then the aluminum target is turned on and kept on until the 27th minute. The copper target is turned on again and turned off after 2 minutes to obtain an aluminum metal film with a twinned copper metal coating layer deposited on the polyimide film. (4) Take out the polyimide film with the composite aluminum metal film deposited, place it in a dry environment at room temperature for 48 hours, gently fold the polyimide film and put it into anhydrous ethanol for ultrasonic peeling of the composite aluminum metal film attached to the polyimide substrate. After taking out the polyimide film, aluminum submicron sheets with a twinned copper metal coating layer are obtained dispersed in anhydrous ethanol. (4) The anhydrous ethanol soaked in aluminum composite submicron sheets is filtered. Nylon filter paper with a pore size of 40nm is selected. After filtration, it is placed in a vacuum drying oven for 8 hours to obtain composite aluminum submicron sheets with a twinned copper metal coating layer. It should be noted that the above examples are only for better illustrating the specific process parameters and should not be regarded as any limitation on the present invention. Those skilled in the art can reasonably determine the specific process parameters based on factors such as the type of metal and the coating thickness in actual operation.

[0045] In some embodiments of the present invention, in step S4, the settling process refers to placing the material in a dry indoor environment at a temperature range of -40°C to 35°C for 1 to 48 hours; preferably at 25°C for 24 hours. The organic solvents include, but are not limited to, ethanol, acetone, and benzene; any solvent that does not react with the prepared composite aluminum sheet at room temperature can be used. The organic solvents are removed by suction filtration.

[0046] In a third aspect, the present invention provides a battery negative electrode material comprising a negative electrode active material, a conductive agent, and a binder, wherein the negative electrode active material is the composite aluminum material described above or a composite aluminum material prepared by the preparation method described above.

[0047] The battery anode material according to embodiments of the present invention has at least the following beneficial effects: The battery anode material proposed in this invention has a structural design of a sheet-like composite aluminum material coated with twinned metal. The sheet-like structure design achieves surface contact between the aluminum materials, significantly reducing the contact resistance between nanoscale or microscale aluminum materials when used as anode materials. Twinned metal has good dual conductivity of ions and electrons; the twinned metal coating design not only provides excellent oxygen barrier properties, preventing rapid oxidation of the aluminum material in air, but also ensures unimpeded electron-ion transport, facilitating the coupling of electrons and ions in the aluminum anode material. Therefore, the structural design of the sheet-like composite aluminum anode material with twinned metal coating effectively reduces the polarization of nanoscale or microscale aluminum-based anode materials and effectively activates their electrochemical activity. The paper also proposes a corresponding preparation method, employing a bottom-up approach to prepare composite aluminum anode materials with twinned metal coatings: Aluminum metal films are deposited on a carbon-plated polymer substrate using physical vapor deposition (PVD). The carbon plating of the polymer substrate facilitates the peeling off of the aluminum metal film. After simple ultrasonic treatment, aluminum sheets with adjustable thickness can be prepared from the bottom up. PVD provides a high-vacuum environment for aluminum sheet growth, solving the problem of continuous oxidation that occurs during bottom-up preparation.

[0048] In some embodiments of the present invention, the conductive agent is selected from acetylene black, conductive carbon black, and graphite, but is not limited thereto. Commonly used conductive additives in the art can also be used to improve the conductivity of electrons generated in the electrode and improve battery performance.

[0049] In some embodiments of the present invention, the binder is selected from styrene-butadiene rubber (SBR) emulsion, carboxymethyl cellulose (CMC), polyethylene oxide (PEO), polypropylene oxide (PPO), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyacrylonitrile (PAN), polymethyl methacrylate (PMA), and polymethyl methacrylate (PMMA), but is not limited thereto. Commonly used negative electrode material binders in the art can be used, with PVDF being the most common.

[0050] In a fourth aspect, the present invention provides a battery negative electrode comprising a current collector and a battery negative electrode material as described above.

[0051] In some embodiments of the present invention, the current collector is a non-active conductive current collector, which may be selected from copper foil (mesh), titanium foil (mesh), iron foil (mesh), nickel foil (mesh), carbon cloth, conductive nylon, etc., but is not limited thereto.

[0052] In a fifth aspect, the present invention provides a battery comprising a battery negative electrode as described above.

[0053] In some embodiments of the present invention, the battery includes half-cells such as button cells and full-cells such as lithium-ion batteries, but is not limited thereto. The negative electrode of the battery provided by the present invention can also be an energy storage device such as a supercapacitor or a hybrid supercapacitor. There are no limitations on the positive electrode active material, separator, electrolyte, etc., used in assembling the battery; commonly used materials in the art can be reasonably used, and will not be elaborated further here. Attached Figure Description

[0054] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0055] Figure 1 This is a schematic diagram of a sheet-like composite aluminum material structure with twinned metal coating in an embodiment of the present invention;

[0056] Figure 2 This is a schematic diagram of the SEM morphology of the twinned copper-clad aluminum submicron sheet material prepared in the embodiments of the present invention;

[0057] Figure 3 This is a schematic diagram illustrating the cross-sectional morphology and thickness characterization of the twinned copper-clad aluminum submicron sheet material prepared in this embodiment of the invention.

[0058] Figure 4 This is a schematic diagram of TEM characterization of twins in the twinned copper cladding layer prepared in an embodiment of the present invention. Detailed Implementation

[0059] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0060] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] In the description of this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. Unless otherwise stated, the various reaction or operation steps may be performed sequentially or not. Preferably, the reaction methods in this invention are performed sequentially.

[0062] Unless otherwise specified in the following examples, the techniques or conditions described in the literature in this field or in accordance with the product instructions shall apply. All reagents or instruments without a specified manufacturer are commercially available conventional products.

[0063] Example 1: Composite aluminum submicron sheet with twinned copper metal coating prepared using polyimide film as substrate

[0064] This embodiment uses a 25μm thick homopolymer polyimide film as a substrate and employs magnetron sputtering to fabricate a composite aluminum submicron sheet with a twinned copper metal cladding layer. The thickness of the twinned copper metal cladding layer is 50nm, and the corresponding thickness of the aluminum metal layer is 500nm. The specific fabrication process is as follows:

[0065] (1) The polyimide film was ultrasonically cleaned with 95% ethanol, and after being fully dried, it was pasted onto the circular roller of the magnetron sputtering instrument. Then, the vacuum coating chamber of the magnetron sputtering instrument was heated to 200°C, and then the pressure was evacuated to 10. -4 Pa.

[0066] (2) A carbon target with a purity of 99.99% was selected, and the deposition power was 1KW. Argon gas with a flow rate of 300sccm was introduced into the vacuum coating chamber to perform carbon pretreatment on the polyimide film. The coating steps are as follows: the film was turned on under a bias voltage of 50V, and deposition was carried out for 5 minutes to obtain the polyimide film after carbon pretreatment. Then it was cooled to room temperature.

[0067] (3) Copper and aluminum targets with a purity of 99.99% were selected. The deposition power of copper was 1KW, and that of aluminum was 2KW. Argon gas with a flow rate of 300 sccm was introduced into the vacuum deposition chamber to raise the temperature of the magnetron sputtering vacuum deposition chamber to 200℃, and then the pressure was evacuated to 10. -4 Pa. The coating steps are as follows: Under a bias voltage of 50V, the copper target is first turned on to deposit on the interface-modified polyimide film for 2 minutes. Then the aluminum target is turned on and kept on until the 27th minute. The copper target is turned on again and turned off after 2 minutes to obtain an aluminum metal film with a twinned copper metal coating layer deposited on the polyimide film.

[0068] (4) Take out the polyimide film with the composite aluminum metal film deposited, place it in a dry environment at room temperature for 48 hours, gently fold the polyimide film and put it into anhydrous ethanol to ultrasonically peel off the composite aluminum metal film attached to the polyimide substrate. After taking out the polyimide film, an aluminum submicron sheet with a twin copper metal coating layer is obtained and dispersed in anhydrous ethanol.

[0069] (4) The anhydrous ethanol impregnated with aluminum composite sub-nano sheets was subjected to vacuum filtration. Nylon filter paper with a pore size of 40 nm was used. After filtration, the sheets were placed in a vacuum drying oven and dried for 8 hours to obtain composite aluminum sub-nano sheets with a twinned copper metal coating.

[0070] To better illustrate the microstructure characteristics of the composite aluminum submicron sheet with a twinned copper metal cladding layer, scanning electron microscopy (SEM) was used to characterize it, such as... Figure 2 As shown, the prepared composite aluminum submicron sheet has a relatively smooth surface and exhibits an irregular sheet-like shape. The morphology of the cross-section of the composite aluminum submicron sheet was further observed using transmission electron microscopy (TEM), as shown... Figure 3 As shown, the prepared composite aluminum submicron sheet with a twinned copper metal cladding layer has a thickness of approximately 600 nm, and its cross-section exhibits a three-layer structure: twinned copper metal cladding layer - aluminum submicron sheet layer - twinned copper metal cladding layer. To verify that the copper metal cladding layer has a twinned structure, transmission electron microscopy was used to further observe the copper metal cladding layer, as shown... Figure 4 As shown, this proves that the crystal structure of metallic copper in the copper metal cladding layer is twinned.

[0071] To illustrate the beneficial effects of this invention, the composite aluminum submicron sheet material with a twinned copper metal coating prepared in Example 1 was used as an electrode for half-cell electrochemical performance testing. In the half-cell, a lithium metal sheet was used as the negative electrode, and the electrode prepared from the composite aluminum submicron sheet material with a twinned copper metal coating described in this example was used as the positive electrode. A polyolefin separator was used, and the electrolyte was 1M LiPF6 / EC:DMC = 1:1. The cells were assembled into a coin cell. The specific preparation steps are as follows:

[0072] (1) Positive electrode preparation: Aluminum submicron sheet material with twinned copper metal coating, carbon black, and polyvinylidene fluoride (PVDF) were ground and mixed evenly in an agate mortar at a mass ratio of 7:2:1. An appropriate amount of N-methylpyrrolidone (NMP) solvent was added and stirred thoroughly until the slurry was slightly fluid. The mixture was then evenly coated onto the surface of copper foil and placed in a vacuum oven to dry at 80°C for 24 hours. The dried electrode sheet was then cut into circular electrode sheets with a diameter of 10 mm using a round hole punch.

[0073] (2) Negative electrode preparation: A 12mm diameter lithium metal sheet is used as the negative electrode of the half-cell.

[0074] (3) Electrolyte preparation: In a glove box filled with argon, add LiPF6 electrolyte salt to a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1, and then stir thoroughly to dissolve.

[0075] (4) Battery assembly and electrochemical testing: After assembling into button cells in a glove box filled with argon gas and with H2O and O2 content less than 0.1ppm, electrochemical performance testing was carried out in an electrochemical workstation.

[0076] To better illustrate the beneficial effects of this invention, comparative experiments were conducted using aluminum powder with a diameter of 500 nm and aluminum submicron sheets without a twinned metal coating layer with a thickness of 500 nm as anode materials. Except for the anode material, all other materials were identical to those used in the half-cell assembly of the aluminum submicron sheet anode with a twinned copper metal coating layer in Example 1, and the preparation steps were also the same. The electrochemical performance test results are shown in Table 1. It can be seen that the sheet-like aluminum submicron sheet anode has lower polarization and a better discharge capacity than the granular submicron aluminum powder anode, proving that the sheet-like structure design is beneficial for reducing the polarization of the submicron aluminum anode and improving its electrochemical performance. However, due to the presence of the surface oxide layer, the improvement in electrochemical performance solely relying on the sheet-like structure design is relatively limited. The composite aluminum submicron sheet anode with a twinned copper metal coating further reduces polarization and significantly improves the discharge capacity, showing a clear advantage in electrochemical performance compared to the traditional aluminum powder anode.

[0077] Table 1. Test data of the composite aluminum submicron sheet negative electrode half-cell of Example 1 of the present invention

[0078]

[0079] Examples 2-5: Preparation of composite aluminum submicron sheets with twinned copper metal cladding layers of different thicknesses using polyimide films as substrates

[0080] The difference between Examples 2-5 and Example 1 lies in the thickness of the composite aluminum submicron sheet; the preparation method of the composite aluminum submicron sheet and the assembly method of the half-cell are the same as in Example 1. In Examples 2-5, the thicknesses of the aluminum metal layer are 100 nm, 200 nm, 300 nm, and 400 nm, respectively, and the thicknesses of the twinned copper metal coating layer are 10 nm, 20 nm, 30 nm, and 40 nm, respectively. The corresponding composite aluminum submicron sheets prepared are 120 nm, 240 nm, 360 nm, and 480 nm, respectively. The electrochemical performance of the half-cell was tested using electrodes made from the composite aluminum submicron sheets with twinned copper metal coating layers prepared in Examples 2-5, and compared with that of Example 1. The test results are shown in Table 2. It can be seen that as the thickness of the aluminum metal layer decreases, the polarization voltage increases slightly. After 300 cycles, the discharge capacity remains above 600 mAh / g.

[0081] Table 2. Test data of composite aluminum submicron sheet negative electrode half-cells in Examples 1-5 of the present invention

[0082]

[0083] Examples 6-11: Preparation of composite aluminum submicron sheets with different types of twinned metal coatings using polyimide films as substrates

[0084] Examples 6-11 differ from Example 1 in the type of twinning metal. The preparation method of the composite aluminum submicron sheet and the half-cell assembly method are the same as in Example 1. The twinning metals used in Examples 6-11 are titanium, zinc, nickel, chromium, zinc-titanium alloy, and zinc-copper alloy, respectively. The thickness of the twinning metal coating layer is 50 nm in all examples, and the thickness of the composite aluminum submicron sheet is 600 nm in all examples. The composite aluminum submicron sheets prepared in Examples 6-11 were used to assemble electrodes into half-cells for electrochemical cycling tests. The test results are shown in Table 3. As can be seen from the table, after 300 cycles, the discharge capacity exceeded 500 mAh / g in all examples.

[0085] Table 3. Test data of composite aluminum submicron sheet negative electrode half-cells in Examples 6-11 of the present invention

[0086]

[0087]

[0088] Examples 12-18: Preparation of composite aluminum submicron sheets with twinned copper metal coatings using different polymer films as substrates

[0089] The difference between Examples 12-18 and Example 1 lies in the polymer film substrate used for preparing the composite aluminum submicron sheets; the other preparation steps are the same. The choice of substrate affects the sheet diameter of the composite aluminum submicron sheets. A laser particle size analyzer was used to test the sheet diameter of the composite aluminum submicron sheets with twinned copper metal coatings prepared in Examples 12-18 and Example 1. The results are shown in Table 4. It can be seen that the obtained composite aluminum submicron sheets all have sheet diameters in the micrometer range, and all are below 100 μm.

[0090] Table 4. Surface diameter test results of the composite aluminum submicron sheets prepared in Examples 12-18 and Example 1 of this invention.

[0091]

[0092] Examples 19-23: Assembly of lithium-ion full cells based on aluminum submicron sheet anode material and lithium cobalt oxide cathode material using twinned copper metal cladding composite.

[0093] Examples 19-23 respectively use the aluminum submicron sheet material with twinned copper metal coating layer prepared in Examples 1-5 of this invention to assemble lithium-ion full batteries, wherein the positive electrode is lithium cobalt oxide, the separator is a polyolefin separator, and the electrolyte is 1M LiPF6 / EC:DMC = 1:1, and they are assembled into coin cells. The specific preparation steps are as follows:

[0094] (1) Preparation of negative electrode material: The aluminum submicron sheet material with twinned copper metal coating layer prepared in Examples 1-5, conductive carbon black and polyvinylidene fluoride (PVDF) were ground and mixed evenly in an agate mortar at a mass ratio of 7:2:1. An appropriate amount of N-methylpyrrolidone (NMP) solvent was added and stirred thoroughly until the slurry was slightly fluid. The mixture was then coated onto the surface of copper foil and dried in a vacuum oven at 80°C for 24 hours. The dried negative electrode sheet was then cut into circular sheets with a diameter of 12 mm using a round hole punch.

[0095] (2) Preparation of positive electrode material: Lithium cobalt oxide positive electrode material, conductive carbon black, and polyvinylidene fluoride (PVDF) were ground and mixed evenly in an agate mortar at a mass ratio of 8:1:1. An appropriate amount of N-methylpyrrolidone (NMP) solvent was added and stirred thoroughly until the slurry was slightly fluid. The mixture was then evenly coated onto the surface of carbon-coated aluminum foil and dried in a vacuum oven at 80°C for 24 hours. The dried positive electrode sheet was then cut into circular sheets with a diameter of 10 mm using a round hole punch.

[0096] (3) Electrolyte preparation: In a glove box filled with argon, add LiPF6 electrolyte salt to a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:1, and then stir thoroughly to dissolve.

[0097] (4) Battery assembly and electrochemical testing: After assembling into button cells in a glove box filled with argon gas and with H2O and O2 content less than 0.1ppm, electrochemical performance testing was carried out in an electrochemical workstation.

[0098] Lithium-ion full cells were assembled using composite aluminum submicron sheet anode materials with twinned copper metal coatings prepared in Examples 1-5, combined with lithium cobalt oxide cathode materials. The electrochemical performance of full cells corresponding to composite aluminum submicron sheet anode materials of different thicknesses was compared. The test results are shown in Table 5. As can be seen from the table, the reversible discharge specific capacity is around 130 mAh / g, and the capacity retention rate is maintained above 95% after 500 cycles of the full cell.

[0099] Table 5. Test data of lithium-ion full batteries based on lithium cobalt oxide cathode material in Examples 19-23 of the present invention.

[0100]

[0101]

[0102] Examples 24-28: Assembly of a dual-ion battery based on a twinned copper metal cladding composite aluminum submicron sheet material and an expanded graphite cathode material.

[0103] Examples 24-28 respectively use the aluminum submicron sheet material with twinned copper metal coating layer prepared in Examples 1-5 of this invention to assemble lithium-ion based dual-ion batteries. Expanded graphite is used as the positive electrode material of the dual-ion battery, a polyolefin separator is used, and 4M LiPF6 / EMC + 2% VC is used as the electrolyte. The batteries are assembled into coin cells. The specific preparation steps are as follows:

[0104] (1) Preparation of negative electrode material: The aluminum submicron sheet material with twinned copper metal coating layer prepared in Examples 1-5, conductive carbon black and polyvinylidene fluoride (PVDF) were ground and mixed evenly in an agate mortar at a mass ratio of 7:2:1. An appropriate amount of N-methylpyrrolidone (NMP) solvent was added and stirred thoroughly until the slurry was slightly fluid. The mixture was then coated onto the surface of copper foil and dried in a vacuum oven at 80°C for 24 hours. The dried negative electrode sheet was then cut into circular sheets with a diameter of 12 mm using a round hole punch.

[0105] (2) Preparation of positive electrode material: Expanded graphite, conductive carbon black, and polyvinylidene fluoride (PVDF) were ground and mixed evenly in an agate mortar at a mass ratio of 8:1:1. An appropriate amount of N-methylpyrrolidone (NMP) solvent was added and stirred thoroughly until the slurry was slightly fluid. The mixture was then evenly coated onto the surface of carbon-coated aluminum foil and placed in a vacuum oven to dry at 80°C for 24 hours. The dried positive electrode sheet was then cut into circular sheets with a diameter of 10 mm using a round hole punch.

[0106] (3) Electrolyte preparation: In a glove box filled with argon, add LiPF6 electrolyte salt to ethyl methyl carbonate (EMC) solvent in proportion, then add 2% by mass of vinylene carbonate (VC) additive, and then stir thoroughly to dissolve.

[0107] (4) Assembly and electrochemical testing of dual-ion batteries: After being assembled into button cells in a glove box filled with argon gas and with H2O and O2 contents less than 0.1ppm, electrochemical performance tests were conducted at an electrochemical workstation.

[0108] Examples 24-28 respectively used the composite aluminum submicron sheet anode material with twinned copper metal coating prepared in Examples 1-5 and expanded graphite as cathode material to assemble lithium-ion based dual-ion full cells. The electrochemical performance of lithium-ion based dual-ion full cells with composite aluminum submicron sheet anode material of different thicknesses was compared. The test results are shown in Table 6. As can be seen from the table, their reversible discharge specific capacity is about 100 mAh / g. After 1000 cycles, the capacity retention rate of the dual-ion battery is maintained at more than 80%.

[0109] Table 6. Test data of dual-ion batteries based on expanded graphite cathode material in Examples 24-28 of the present invention.

[0110]

[0111]

[0112] Compared to Examples 19-23, although the battery capacity of Examples 24-28 is somewhat reduced due to the capacity of the dual-ion battery cathode material, compared to the expensive lithium cobalt oxide cathode material in Examples 19-23, Examples 24-28 use economical expanded graphite as the cathode, resulting in a significant cost reduction. At the same time, the reversible discharge specific capacity of the batteries is around 100 mAh / g, and the capacity retention rate of the dual-ion batteries remains above 80% after 1000 cycles, thus reducing costs while meeting the basic requirements of a full battery.

[0113] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A battery negative electrode active material, characterized in that, The material includes a composite aluminum material comprising an aluminum sheet and a twinned metal material. The twinned metal material coats the upper and lower surfaces of the aluminum sheet, forming an upper twinned metal coating layer and a lower twinned metal coating layer. The aluminum sheet is located between the upper twinned metal coating layer and the lower twinned metal coating layer, forming a sandwich structure.

2. The battery negative electrode active material according to claim 1, characterized in that, The thickness of the aluminum sheet is 1 nm to 100 μm.

3. The battery negative electrode active material according to claim 2, characterized in that, The thickness of the aluminum sheet is 100nm to 500nm.

4. The battery negative electrode active material according to claim 1, characterized in that, The aluminum sheet has a diameter of 1μm to 200μm.

5. The battery negative electrode active material according to claim 4, characterized in that, The aluminum sheet has a diameter of 10μm to 100μm.

6. The battery negative electrode active material according to claim 1, characterized in that, The thickness of the upper twin metal coating layer is 1 nm to 300 nm.

7. The battery negative electrode active material according to claim 6, characterized in that, The thickness of the upper twinned metal coating layer is 1 nm to 50 nm.

8. The battery negative electrode active material according to claim 1, characterized in that, The thickness of the lower twin metal cladding layer is 1 nm to 300 nm.

9. The battery negative electrode active material according to claim 8, characterized in that, The thickness of the lower twin metal cladding layer is 1 nm to 50 nm.

10. The battery negative electrode active material according to claim 1, characterized in that, The twinned metal material is selected from single-element materials composed of single elements in Groups I to VII, Group VIII, Group III, and Group IV, or alloys or composite materials composed of multiple elements.

11. The battery negative electrode active material according to claim 10, characterized in that, The twinned metal material is titanium, zinc, nickel, chromium, zinc-titanium alloy, or zinc-copper alloy.

12. A method for preparing the negative electrode active material of a battery as described in any one of claims 1-11, characterized in that, Including the following steps: A polymer film substrate is provided, and the polymer film substrate is cleaned. The cleaned polymer film substrate is subjected to a carbon plating pretreatment to obtain a carbon-plated polymer film substrate. Using physical vapor deposition technology, a lower twinned metal film layer, an aluminum metal film layer, and an upper twinned metal film layer are successively deposited on the surface of the carbon-plated polymer film substrate to form a composite aluminum metal film with a sandwich structure. After the carbon-plated polymer film substrate on which the composite aluminum metal film is deposited is left to stand, it is placed in an organic solvent for ultrasonic treatment to peel off the carbon-plated polymer film. Then the organic solvent is removed to obtain the negative electrode active material of the battery.

13. The method for preparing the negative electrode active material of a battery according to claim 12, characterized in that, The polymer film substrate includes polyimide film, carbonate film, polyethylene terephthalate film, polypropylene film, polyethylene film, polyvinyl chloride film, polytetrafluoroethylene film, polystyrene film, and polyvinylidene fluoride.

14. The method for preparing the negative electrode active material of a battery according to claim 12, characterized in that, The thickness of the polymer film substrate is 3μm to 100μm.

15. The method for preparing the negative electrode active material of a battery according to claim 14, characterized in that, The thickness of the polymer film substrate is 10 μm to 25 μm.

16. The method for preparing the negative electrode active material of a battery according to claim 12, characterized in that, The carbon plating pretreatment includes depositing an amorphous carbon layer on the surface of the polymer film substrate, wherein the thickness of the amorphous carbon layer is 1 nm to 50 nm.

17. The method for preparing the negative electrode active material of a battery according to claim 16, characterized in that, The thickness of the amorphous carbon layer is 10 nm to 20 nm.

18. The method for preparing the negative electrode active material of a battery according to claim 12, characterized in that, The static treatment includes placing the container at a temperature of -40℃ to 35℃ for 1 hour to 48 hours.

19. The method for preparing the negative electrode active material of a battery according to claim 12, characterized in that, The physical vapor deposition technology includes vacuum evaporation coating technology, vacuum magnetron sputtering technology, and ion plating technology.

20. A battery negative electrode material, characterized in that, It includes a negative electrode active material, a conductive agent, and a binder, wherein the negative electrode active material is the battery negative electrode active material according to any one of claims 1-11 or the battery negative electrode active material prepared by the preparation method according to any one of claims 12-19.

21. A battery negative electrode, characterized in that, It includes current collectors and the battery negative electrode material as described in claim 20.

22. A battery, characterized in that, Includes the battery negative electrode as described in claim 21.

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