A battery case material, a method for manufacturing the same, and a battery

Abstract

The application discloses a battery shell material and a preparation method and a battery thereof, and belongs to the technical field of lithium batteries. The battery shell material provided by the application comprises an aluminum alloy base body, the outer surface of the aluminum alloy base body is provided with an integrally-formed scale structure, the grain size of the surface of the scale structure is smaller than that of the inside of the aluminum alloy base body, and the surface of the scale structure is covered with a nano-crystal copper plating layer. The scale structure directly increases the contact area of the shell with air, and strengthens the heat dissipation efficiency of convection; the small-grain surface significantly improves the strength and deformation resistance of the material; and the high-thermal-conductivity nano-crystal copper plating layer further accelerates the transverse diffusion of heat from the base body to the scale surface and the outside. The combination of the three can meet the dual requirements of high-power batteries on high-efficiency heat dissipation and high safety strength without the need of additional complex cooling components.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a battery casing material, its preparation method, and a battery. Background Technology

[0002] With the continuous improvement of energy density and power density of lithium-ion batteries, their heat generation has increased significantly, placing higher demands on heat dissipation efficiency. Currently, the commonly used aluminum alloy battery casings have limited thermal conductivity, and their smooth surfaces result in insufficient effective heat dissipation area, relying mainly on natural convection for cooling, which is inefficient. To improve heat dissipation, additional cooling systems or complex heat dissipation structures are often introduced at the battery pack level, increasing the overall weight, volume, and manufacturing cost of the system. Furthermore, conventional aluminum casings generally have low mechanical strength and are prone to deformation under mechanical impact or extrusion conditions, posing a risk of short circuits in the internal cells.

[0003] Therefore, how to simultaneously possess excellent heat dissipation performance and high structural strength in the casing material itself under the constraints of lightweight and highly integrated battery pack design is a prominent technical challenge in this field. Summary of the Invention

[0004] In view of this, the present invention provides a battery casing material, a method for preparing the same, and a battery. The present invention improves the heat dissipation efficiency and structural strength of the casing by integrally forming a scale structure on the surface of the casing substrate and composited with a nanocrystalline copper plating layer.

[0005] In a first aspect, the present invention provides a battery casing material comprising an aluminum alloy substrate, wherein the outer surface of the aluminum alloy substrate has an integrally formed scale structure, the grain size of the scale structure surface is smaller than the grain size inside the aluminum alloy substrate, and the surface of the scale structure is covered with a nanocrystalline copper plating layer.

[0006] Preferably, the scale structure is composed of a plurality of protruding units extending along a first direction, and the protruding units are arranged in a second direction perpendicular to the first direction to form a multi-row protrusion array.

[0007] Furthermore, the protruding units in two adjacent rows are staggered in the second direction; the protruding units are arc-shaped protrusions.

[0008] Furthermore, the protrusion height of the protrusion unit is 0.2~1 mm; the center distance between adjacent protrusion units in the same row is 3.0~8.0 mm.

[0009] Preferably, the thickness of the nanocrystalline copper coating is 5~10 μm, and the grain size of the nanocrystals in the nanocrystalline copper coating is 100~800 nm.

[0010] Secondly, the present invention provides a method for preparing the above-mentioned battery casing material, comprising the following steps: Provide aluminum alloy substrate; The surface of the aluminum alloy substrate is subjected to ultrasonic roll pressing to obtain a surface nano-sized aluminum alloy material. The surface nano-sized aluminum alloy material is subjected to non-ultrasonic roll forming to integrally form a scale structure; Nanocrystalline copper is electroplated onto the surface of the scale structure to form a nanocrystalline copper plating layer, thus obtaining the battery casing material.

[0011] Preferably, the thickness of the aluminum alloy substrate is 3~8mm; the pressure of the ultrasonic roll forming cutter head is 0.1~0.5 mm / pass, and the number of roll forming passes is 4~8; the pressure of the cutter head in the non-ultrasonic roll forming process is 1~3 mm / pass.

[0012] Preferably, the plating solution used for electroplating nanocrystalline copper includes copper salt, concentrated sulfuric acid, and thiourea, wherein the copper salt includes at least one of copper sulfate, copper chloride, and copper nitrate.

[0013] Thirdly, the present invention provides a battery casing made from the battery casing material described above or the battery casing material prepared by the above preparation method.

[0014] Fourthly, the present invention provides a battery comprising the aforementioned battery casing.

[0015] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) This invention achieves a synergistic improvement in passive heat dissipation and mechanical properties by integrally forming a flake structure on the surface of an aluminum alloy substrate and covering it with a nanocrystalline copper plating layer. The flake structure directly increases the contact area between the shell and the air, enhancing the convective heat dissipation efficiency; the fine grains on the surface significantly improve the strength and deformation resistance of the material; and the highly thermally conductive nanocrystalline copper plating layer further accelerates the lateral diffusion of heat from the substrate to the flake surface and the outside world. The combination of these three factors allows the shell material itself to meet the dual requirements of high-power batteries for efficient heat dissipation and high safety strength without the need for additional complex cooling components.

[0016] (2) The present invention first performs ultrasonic rolling on the surface of the aluminum alloy substrate to achieve grain refinement, then integrally forms a scale structure through non-ultrasonic rolling, and finally performs electroplating. The overall steps are highly controllable. This method not only ensures the continuous transition between the scale structure and the substrate, ensuring excellent mechanical bearing and thermal conductivity interface, but also achieves an effective combination of surface microstructure (nanocrystalline) and macro morphology (scale) through step-by-step processing, further improving the material strength and thermal conductivity efficiency, and providing a feasible process path for the large-scale production of battery shell materials with excellent comprehensive performance.

[0017] (3) The present invention effectively overcomes the shortcomings of the traditional smooth aluminum shell, which has limited heat dissipation area and thermal conductivity bottleneck, and avoids the increase in weight, volume and cost caused by the additional installation of heat dissipation components. The battery shell made of this material can more efficiently dissipate and dissipate heat at the source of battery operation, thereby helping to reduce the cell operating temperature, delay capacity decay, improve cycle life, and enhance the safety and reliability of the battery under mechanical impact due to the higher shell strength. Attached Figure Description

[0018] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0019] Figure 1 This is a schematic diagram of the scale structure in a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the process flow for preparing the battery casing material in a specific embodiment of the present invention; Figure 3 These are comparison diagrams showing the highest surface temperature of the battery casing material and cell at 3C rate discharge for Embodiments 1-2 and Comparative Example 1 of the present invention. Detailed Implementation

[0020] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, 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.

[0021] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, it may be directly "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, or there may be one or more other elements in between. In contrast, when an element is described as being "directly on" another element, "directly connected to" another element, "directly bonded to" another element, "directly on" another element, or "directly covering" another element, there may be no other elements in between.

[0022] As used herein, the term “and / or” includes any one of the relevant items listed and any combination of any two or more items.

[0023] Although terms such as “first,” “second,” and “third” may be used herein to describe individual components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teachings of the examples described herein, the first component, assembly, region, layer, or part referred to as the second component, assembly, region, layer, or part may also be referred to as the second component, assembly, region, layer, or part.

[0024] For ease of description, spatial relation terms such as “above,” “upper,” “below,” and “lower” are used herein to describe the relationship between one element and another, as shown in the accompanying drawings. Such spatial relation terms are intended to include not only the orientation depicted in the drawings but also different orientations of the device during use or operation. For example, if the device in the drawings is flipped, an element described as being “above” or “upper” relative to another element will subsequently be “below” or “lower” relative to that other element. Therefore, the term “above” includes both “above” and “below” orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relation terms used herein will be interpreted accordingly.

[0025] The terminology used herein is for describing various examples only and is not intended to limit the invention. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms “comprising,” “including,” and “having” enumerate the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0026] The battery casing material, its preparation method, and the battery of the present invention will be described below with reference to the accompanying drawings.

[0027] In one embodiment of the present invention, a battery casing material is provided, comprising an aluminum alloy substrate as the main load-bearing body. The aluminum alloy substrate can be selected from series aluminum alloys such as 3003, 3004, and 5052, but is preferably made of 3003 series aluminum alloys, as it has good formability, corrosion resistance, and moderate strength, making it a commonly used material for power battery casings.

[0028] The outer surface of the aluminum alloy substrate has an integrally formed scale structure. Here, "integral forming" means that the scale structure is not combined with the substrate by welding, bonding or other additional methods, but is formed directly from the substrate material through a plastic deformation process. This ensures that the scale and the substrate are metallurgically bonded, and there is no interface with high thermal resistance, thus guaranteeing excellent structural integrity and thermal conductivity.

[0029] In this invention, the structural diagram of the scale structure is as follows: Figure 1 As shown, the battery is composed of multiple raised units extending along a first direction (e.g., the length direction of the battery casing or a roll forming direction suitable for processing). These raised units are arranged along a second direction perpendicular to the first direction (e.g., the width direction of the battery casing), forming a multi-row array of raised units. To further optimize the heat dissipation airflow path and increase the effective heat dissipation area, adjacent rows of raised units are preferably staggered in the second direction. Each raised unit is an arc-shaped protrusion, and its cross-sectional profile can be a continuous arc curve, such as a semi-ellipse or parabola. This streamlined structure helps guide airflow, reduce wind resistance, and enhance convective heat transfer.

[0030] In some preferred embodiments, the protrusion height (i.e., the vertical distance from the substrate surface to the protrusion apex) of the protruding unit is designed to be 0.2~1.0 mm. This height range ensures a significant increase in heat dissipation area while also considering the overall rigidity of the material and the feasibility of subsequent stamping processes. Within the same row, the center-to-center spacing between adjacent protruding units is designed to be 3.0~8.0 mm. This spacing is coordinated with the protrusion height, enabling the formation of a reasonable scale density per unit area. This avoids both excessively dense spacing that would obstruct airflow and excessively wide spacing that would result in a negligible increase in heat dissipation area.

[0031] In this invention, the grain size on the surface of the scale structure is smaller than the grain size inside the aluminum alloy matrix. This fine-grained surface layer can effectively prevent dislocation movement and significantly improve the surface strength, hardness, and fatigue performance of the material.

[0032] In this invention, a nanocrystalline copper plating layer covers the entire outer surface of the scale structure. The nanocrystalline copper plating layer is formed by electroplating and is firmly bonded to the surface of the scale structure. The thickness of the plating layer is 5-10 μm. The copper grains in the plating layer are nanoscale, with a grain size of 100-800 nm, more preferably 200-600 nm. The nanocrystalline copper plating layer has a dual function: firstly, the thermal conductivity of copper (approximately 400 W / (m·K)) is much higher than that of aluminum alloy (approximately 180 W / (m·K)). This plating layer acts like a high-speed heat conduction network on the scale surface, enabling rapid lateral diffusion of heat generated inside the battery to the entire scale surface, overcoming the bottleneck of the thermal conductivity of aluminum alloy itself; secondly, the nanocrystalline structure itself has high strength, and this plating layer further strengthens the scale surface, working synergistically with the finely grained aluminum substrate to jointly improve the overall mechanical properties of the shell material.

[0033] In another embodiment of the present invention, a method for preparing the above-mentioned battery casing material is also provided. This method is a continuous process and suitable for mass production. See also Figure 2 The process flow diagram shown indicates that the method includes the following steps: S1: Provides an aluminum alloy substrate.

[0034] Select an aluminum alloy sheet that meets the composition requirements, such as a 3003 aluminum alloy sheet. The initial thickness of the aluminum alloy substrate can be determined based on the target wall thickness of the final battery casing and the subsequent stamping thinning rate. As a processing starting point, its thickness can be, for example, 3~8 mm, more preferably 4~6 mm. This thickness is the original sheet thickness before subsequent surface modification, after ultrasonic rolling and without ultrasonic rolling.

[0035] S2: The surface of the aluminum alloy substrate is subjected to ultrasonic rolling treatment to obtain a surface nano-sized aluminum alloy material.

[0036] An aluminum alloy substrate is fixed, and its surface to be treated is reciprocatedly rolled using a rolling device equipped with an ultrasonic generator. The ultrasonic frequency is preferably 10~50 kHz, more preferably 10~30 kHz; the high-frequency vibration generated by the ultrasonic generator, superimposed on the static pressure, can effectively reduce the material's deformation resistance and promote dislocation movement and proliferation. By controlling the cutting head pressure and the number of rolling passes, intense plastic deformation is introduced into the material surface layer, thereby achieving significant grain refinement. The cutting head pressure in the ultrasonic rolling treatment is 0.1~0.5 mm / pass, and the number of rolling passes is 4~8. After this step, a nanocrystalline / ultrafine crystalline structure with a depth of tens to hundreds of micrometers is formed on the surface layer of the substrate, while the overall thickness of the substrate remains essentially unchanged or only slightly reduced.

[0037] S3: The surface nano-sized aluminum alloy material is subjected to non-ultrasonic rolling treatment to form a scale structure in one piece.

[0038] By replacing or adjusting the roller pressing device, and without activating the ultrasonic waves, a roller pressing head of a specific shape is used to precisely plastically shape the surface treated in step S2. By controlling the pressure of the non-ultrasonic roller pressing head (preferably 1~3 mm / pass) and the interval between adjacent roller pressing passes (preferably 3~8 mm), a designed array of scale-like protrusions is formed on the already finely crystalline surface layer. This step is a combined shaping of macroscopic and microscopic structures: microscopically, it inherits the fine-grained structure of step S2, and macroscopically, it shapes an enlarged heat dissipation surface morphology.

[0039] S4: Electroplating nanocrystalline copper on the surface of the scale structure to form a nanocrystalline copper coating, thus obtaining the battery casing material.

[0040] After undergoing conventional pretreatments such as degreasing and activation, the plate with a scaly structure is placed in an electroplating bath for electroplating. The plating solution contains copper salts, concentrated sulfuric acid, and a trace amount of the additive thiourea. The copper salts include at least one of copper sulfate, copper chloride, and copper nitrate. Thiourea, as a grain refiner, helps to obtain a nanocrystalline structure. The current density (preferably 10~50 mA / cm²) is controlled. 2 The electroplating process involves uniformly depositing a dense, continuous nanocrystalline copper coating onto the complex, scaly surface with a thickness controlled at 5–10 μm, using a specific deposition time (preferably 5–20 min). After electroplating, the material is washed with water and dried to obtain the final battery casing material.

[0041] Subsequently, this battery casing material can be processed into a specific battery casing using traditional forming processes such as stamping and stretching. During the stamping process, the main body of the substrate is further thinned to the required final casing wall thickness, while the areas with the already formed scale structure and coating mainly undergo shape bending rather than significant thickness changes, thus obtaining a final battery casing product that combines excellent heat dissipation performance and high strength.

[0042] In another embodiment of the present invention, a battery casing is also provided, which is made of the battery casing material described above or the battery casing material prepared by the above preparation method. The specific manufacturing method is not particularly limited; for example, it can be formed through subsequent processing such as stamping and welding. Due to the efficient heat dissipation and high strength characteristics of its material body, this battery casing can significantly improve the thermal management capability and safety performance of the battery module.

[0043] In another embodiment of the present invention, a battery is also provided, which includes the aforementioned battery casing. This battery is particularly suitable for scenarios requiring high energy density and high power charging and discharging, such as electric vehicles and energy storage power stations. The heat generated by the battery cells inside the battery can be efficiently dissipated through the scale structure of the casing material itself and the nanocrystalline copper plating, thereby reducing the cell operating temperature, delaying capacity decay, and improving cycle life and safety reliability.

[0044] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0045] Example 1 This embodiment provides a battery casing material, the preparation method of which includes the following steps: (1) Surface ultrasonic rolling treatment: An aluminum alloy substrate with grade 3003, size 50cm×50cm, and thickness 6mm was selected. The substrate surface was treated by ultrasonic rolling equipment with a reciprocating process. The ultrasonic frequency was 20kHz, the rolling head pressure was 0.2mm / pass, and a total of 6 passes were performed to obtain a nano-sized aluminum alloy material. This step, through ultrasonic-assisted intense plastic deformation, significantly refined the grains on the surface of the aluminum alloy substrate, forming a nano-sized surface layer with a grain size of submicron, while the overall thickness of the substrate remained basically unchanged.

[0046] (2) Integrated forming of scale structure: On the surface of the nano-sized aluminum alloy material treated in step (1), a non-ultrasonic forming roller head is used. The cutting depth of the head is controlled to be 2 mm / pass, and rolling is performed in the same direction. The center line spacing between adjacent rolling passes is 5 mm, for a total of 100 passes. Through this pass spacing control, multiple arc-shaped protrusion units extending along the rolling direction and arranged vertically are integrally formed on the material surface. These protrusion units form a multi-row protrusion array, and the protrusion units in adjacent rows are naturally staggered. In the final scale structure, the protrusion height of the protrusion unit is about 0.8 mm, and the center distance between adjacent protrusion units in the same row is 5 mm.

[0047] (3) Copper plating to form a nanocrystalline copper coating: The aluminum alloy material with a scaly structure undergoes conventional pretreatment such as degreasing and pickling activation. Subsequently, it is placed in an electroplating bath for electroplating. The plating solution composition is: copper sulfate 120 g / L, copper chloride 100 g / L, concentrated sulfuric acid 60 g / L, and thiourea 0.02 g / L. The plating is carried out at a current density of 30 mA / cm². 2 Electroplating was performed at room temperature for 10 minutes. Finally, a continuous, dense nanocrystalline copper plating layer was formed over the entire outer surface of the flake structure. The plating thickness was measured to be approximately 10 μm, with copper grain sizes ranging from 200 to 600 nm.

[0048] Example 2 This embodiment provides a battery casing material, the preparation method of which includes the following steps: (1) Surface ultrasonic rolling treatment: An aluminum alloy substrate with grade 3003, size 50cm×50cm, and thickness 6mm was selected. The substrate surface was treated by ultrasonic rolling equipment with a reciprocating process. The ultrasonic frequency was 20kHz, the rolling head pressure was 0.2mm / pass, and a total of 6 passes were performed to obtain a nano-sized aluminum alloy material. This step, through ultrasonic-assisted intense plastic deformation, significantly refined the grains on the surface of the aluminum alloy substrate, forming a nano-sized surface layer with a grain size of submicron, while the overall thickness of the substrate remained basically unchanged.

[0049] (2) Integrated forming of scale structure: On the surface of the nano-sized aluminum alloy material treated in step (1), a non-ultrasonic forming roll cutter head is used. The cutter head pressure is controlled at 1 mm / pass, and the roll is performed in the same direction. The center line spacing between adjacent roll passes is 5 mm, for a total of 100 passes. Through this pass spacing control, multiple arc-shaped protrusion units extending along the roll pressing direction and arranged in the vertical direction are integrally formed on the material surface. These protrusion units form a multi-row protrusion array, and the protrusion units in adjacent rows are naturally staggered. In the final scale structure, the protrusion height of the protrusion unit is about 0.4 mm, and the center distance between adjacent protrusion units in the same row is 5 mm.

[0050] (3) Copper plating to form a nanocrystalline copper coating: The aluminum alloy material with a scaly structure undergoes conventional pretreatment such as degreasing and pickling activation. Subsequently, it is placed in an electroplating bath for electroplating. The plating solution composition is: copper sulfate 120 g / L, copper chloride 100 g / L, concentrated sulfuric acid 60 g / L, and thiourea 0.02 g / L. The plating is carried out at a current density of 30 mA / cm². 2 Electroplating was performed at room temperature for 10 minutes. Finally, a continuous, dense nanocrystalline copper plating layer was formed over the entire outer surface of the flake structure. The plating thickness was measured to be approximately 10 μm, with copper grain sizes ranging from 200 to 600 nm.

[0051] Comparative Example 1 The difference between this comparative example and Example 1 is that this comparative example does not perform surface ultrasonic rolling treatment, integrated scaling of the scale structure, or copper plating on the aluminum alloy substrate.

[0052] Comparative Example 2 The difference between this comparative example and Example 1 is that step (3) is not performed in this comparative example, while the remaining steps are the same as in Example 1. The final material surface is an exposed aluminum alloy flake structure with a fine grain layer.

[0053] Comparative Example 3 The difference between this comparative example and Example 1 is that step (2) is not performed in this comparative example, while the remaining steps are the same as in Example 1. Finally, a nanocrystalline copper plating layer with a thickness of about 10 μm is electroplated on the flat surface of the nano-sized aluminum alloy material.

[0054] Test case 1. Material mechanical property testing Standard tensile specimens were cut along the same direction from the materials prepared in Examples 1-2 and Comparative Examples 1-3. Tensile tests were performed using a universal testing machine, and the tensile strength and elongation at break of the materials were recorded. This test is used to quantify the enhancing effect of surface nanostructuring, flake structures, and copper plating on the bulk strength of the materials.

[0055] 2. Simulated battery casing heat dissipation performance test (3C rate discharge temperature rise test) The materials prepared in Examples 1-2 and Comparative Examples 1-3 were processed into flat samples with dimensions of 100mm × 50mm, simulating a large surface of a battery casing. Each sample was tightly bonded to the large surface of a standard commercial soft-pack lithium-ion battery cell (rated capacity 5Ah) using thermally conductive silicone grease to form a test unit. All test units were placed in a 25°C constant temperature chamber. The battery cell was subjected to constant current discharge at a rate of 3C (15A) until the cutoff voltage of 2.0V. The temperature change of the outer surface of the sample was monitored and recorded in real time using a temperature sensor. The temperature rise (ΔT) was calculated using the formula: ΔT = T max - T initial T initial The initial ambient temperature (25℃), T max This represents the highest temperature on the sample surface during the discharge process. This test directly reflects the heat dissipation capacity of the casing material under actual high-rate discharge conditions.

[0056] The test results are summarized in Table 1. A comparison of the highest surface temperature of the battery casing material and cell at 3C rate discharge for Examples 1-2 and Comparative Example 1 is shown in the figure. Figure 3 As shown (n=50), the horizontal axis represents the battery number, with 50 batteries in each group, and the vertical axis represents the highest temperature T of the large surface area of ​​the battery cell during 3C discharge. max .

[0057] Table 1 Performance comparison of Examples 1-2 and Comparative Examples 1-3

[0058] It can be seen that the tensile strength of Example 1 (403.5 MPa) is much higher than that of Comparative Example 1 (213.5 MPa), which is attributed to the combined strengthening effect of fine grain reinforcement brought about by surface ultrasonic nano-sizing and the nanocrystalline copper coating. The higher strength of Comparative Example 2 is mainly due to fine grain reinforcement, while the strength improvement of Comparative Example 3 is limited, indicating that the coating alone has a weak effect and needs to be combined with substrate reinforcement. Example 1 exhibits the lowest temperature rise (8.76℃) and the best heat dissipation performance. This proves the synergistic effect of the scale structure increasing the heat dissipation area and the nanocrystalline copper coating improving thermal conductivity.

[0059] Therefore, it can be seen that the battery casing material provided in this embodiment of the invention, through unique structural design and process combination, has achieved significant and synergistic improvement in two key indicators: passive heat dissipation efficiency and body mechanical strength, providing an effective solution to the thermal management and safety challenges of high-power batteries.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A battery casing material, characterized in that, The material includes an aluminum alloy substrate, the outer surface of which has an integrally formed scale structure. The grain size on the surface of the scale structure is smaller than the grain size inside the aluminum alloy substrate, and the surface of the scale structure is covered with a nanocrystalline copper plating layer.

2. The battery casing material as described in claim 1, characterized in that, The scale structure is composed of multiple protruding units extending along a first direction, and the protruding units are arranged in a second direction perpendicular to the first direction to form a multi-row protrusion array.

3. The battery casing material as described in claim 2, characterized in that, The two adjacent rows of raised units are staggered in the second direction; the raised units are arc-shaped protrusions.

4. The battery casing material as described in claim 2, characterized in that, The protrusion height of the protrusion unit is 0.2~1mm; the center distance between adjacent protrusion units in the same row is 3.0~8.0 mm.

5. The battery casing material as described in claim 1, characterized in that, The thickness of the nanocrystalline copper coating is 5~10 μm, and the grain size of the nanocrystals in the nanocrystalline copper coating is 100~800 nm.

6. The method for preparing the battery casing material according to any one of claims 1 to 5, characterized in that, Includes the following steps: Provide aluminum alloy substrate; The surface of the aluminum alloy substrate is subjected to ultrasonic roll pressing to obtain a surface nano-sized aluminum alloy material. The surface nano-sized aluminum alloy material is subjected to non-ultrasonic roll forming to integrally form a scale structure; Nanocrystalline copper is electroplated onto the surface of the scale structure to form a nanocrystalline copper plating layer, thus obtaining the battery casing material.

7. The preparation method according to claim 6, characterized in that, The thickness of the aluminum alloy substrate is 3~8mm; the pressure of the ultrasonic roll forming cutter head is 0.1~0.5 mm / pass, and the number of roll forming passes is 4~8; the pressure of the cutter head in the non-ultrasonic roll forming process is 1~3 mm / pass.

8. The preparation method according to claim 6, characterized in that, The plating solution used for electroplating nanocrystalline copper includes copper salts, concentrated sulfuric acid, and thiourea. The copper salts include at least one of copper sulfate, copper chloride, and copper nitrate.

9. A battery casing, characterized in that, The battery casing material is prepared by the battery casing material according to any one of claims 1 to 5 or by the preparation method according to any one of claims 6 to 8.

10. A battery, characterized in that, Includes the battery casing as described in claim 9.

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