Aluminum alloy and preparation method thereof, box body for packaging battery, battery and electric equipment

Abstract

The invention relates to an aluminum alloy and a preparation method thereof, a box body for packaging a battery, the battery and electric equipment. The aluminum alloy comprises the following components in percentage by mass: 0.45%-0.55% of Si; fe < = 0.25%; 0.10% to 0.16% of Cu; less than or equal to 0.05% of Mn; 0.45% to 0.55% of Mg; less than or equal to 0.05% of Cr; 0.05% or less of Zn; less than or equal to 0.05% of Ti; and the balance of Al and inevitable impurities. By controlling the contents of elements such as Si, Mg and Cu in the range, the aluminum alloy has medium strength, low quenching sensitivity and better extrusion performance capable of being applied to industrial production. In addition, the alloy is low in cost, and medium strength can be obtained under the condition of low cost; therefore, the structure can be suitable for parts, such as side plates, end plates and the like, with low requirements on the structural strength of the lithium ion battery box body, so that the cost is greatly reduced.

Description

Technical Field

[0001] The present application relates to an aluminum alloy and a preparation method thereof, a box for packaging batteries, a battery, and electrical equipment. Background Art

[0002] In recent years, with the development of lithium-ion battery technology, lithium-ion batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. As lithium-ion batteries have made great progress, it is necessary to better balance the performance and cost of lithium-ion batteries. Summary of the invention

[0003] The purpose of the present application is to provide an aluminum alloy and a preparation method thereof, a box for packaging batteries, a battery, and electrical equipment.

[0004] The embodiment of the present application is implemented as follows:

[0005] In a first aspect, an embodiment of the present application provides an aluminum alloy, the composition and mass percentage of the aluminum alloy are:

[0006] Si 0.45%-0.55%; Fe≤0.25%; Cu 0.10%-0.16%; Mn≤0.05%; Mg0.45%-0.55%; Cr≤0.05%; Zn≤0.05%; Ti≤0.05%; the balance is Al and unavoidable impurities.

[0007] In the above technical solution, by controlling the contents of Si, Mg, Cu, etc. within the above ranges, the aluminum alloy has medium strength, low quenching sensitivity, and good extrusion performance that can be used in industrial production. In addition, the alloy has a low cost and can obtain medium strength at a low cost; thus, it can be applied to parts of the lithium-ion battery box structure with low strength requirements, such as side panels, end panels, etc., thereby greatly reducing costs.

[0008] Furthermore, Mn and Cr are elements that can significantly increase the quenching sensitivity of the alloy. In the above technical solution, the mass percentages of Mn and Cr are strictly controlled to control Mn≤0.05%; Cr≤0.05%, which can effectively reduce the quenching sensitivity of the alloy.

[0009] The alloy is highly sensitive to quenching and requires water cooling or mist cooling to ensure quenching strength. This will lead to uneven distribution of residual stress generated during quenching and deformation of the profile, such as flatness, bending and twisting in the length direction, which cannot meet the product's use requirements.

[0010] The above technical solution, by reducing the quenching sensitivity of aluminum alloy, can realize quenching by air cooling, which greatly improves the problems of uneven residual stress distribution and profile deformation caused by conventional water cooling or mist cooling quenching, and improves the product qualification rate.

[0011] Furthermore, adding an appropriate amount of Cu element can improve the solid solution strengthening effect of the alloy and improve the mechanical properties of the product. After research, in the above technical solution, controlling the mass percentage of Cu element at 0.10%-0.16% can effectively improve the mechanical properties of the product, so that the aluminum alloy product has medium-strength mechanical properties, making the tensile strength of the aluminum alloy ≥260Mpa; the yield strength of the aluminum alloy ≥240MPa; the elongation of the aluminum alloy after fracture ≥8%. This aluminum alloy can be well applied to parts of the lithium-ion battery box with low structural strength requirements, such as side panels, end panels, etc., thereby greatly reducing costs; while meeting the structural mechanical strength requirements.

[0012] In some optional embodiments, the composition and mass percentage of the aluminum alloy are:

[0013] Si 0.45%-0.50%; Fe≤0.25%; Cu 0.10%-0.15%; Mn≤0.05%; Mg0.45%-0.51%; Cr≤0.05%; Zn≤0.05%; Ti≤0.05%; the balance is Al and unavoidable impurities.

[0014] In the above technical solution, the content of each element is further strictly controlled within the above range to obtain an aluminum alloy with better comprehensive performance.

[0015] In some optional embodiments, the mass ratio of Mg to Si is 0.9-1.0.

[0016] In the above technical solution, the mass ratio of Mg to Si is controlled to be 0.9-1.0, and the strength, quenching sensitivity and extrusion performance of the aluminum alloy can be better controlled within the target range.

[0017] In some optional embodiments, in terms of mass percentage, Mn+Mg+Zn≤0.55%.

[0018] In the above technical solution, controlling Mn+Mg+Zn≤0.55% can better control the strength, quenching sensitivity and extrusion performance of the aluminum alloy within the target range.

[0019] In some optional embodiments, the unavoidable impurities are ≤ 0.10% by mass.

[0020] In some optional embodiments, when the unavoidable impurities include multiple components, the mass percentage of a single component is less than or equal to 0.03%.

[0021] In the above technical solution, the mass percentage of impurities of a single component is controlled to be less than or equal to 0.03%, which can avoid the aggregation of a single component and stabilize the performance of the aluminum alloy.

[0022] In some optional embodiments, the aluminum alloy has the following characteristics under the condition of air-cooling quenching with a cooling intensity of 5°C / s:

[0023] (a) The tensile strength of aluminum alloy is ≥260Mpa;

[0024] (b) The yield strength of aluminum alloy is ≥240MPa;

[0025] (c) The elongation after fracture of the aluminum alloy is ≥8%.

[0026] The higher the quenching cooling intensity, the better the tensile strength, yield strength and elongation of the aluminum alloy.

[0027] In the above technical solution, the aluminum alloy can have the goals of tensile strength ≥ 260 MPa, yield strength ≥ 240 MPa, and elongation after fracture ≥ 8% under the condition of air-cooling quenching with a cooling intensity of 5°C / s.

[0028] Water cooling or mist cooling quenching will cause uneven distribution of residual stress generated during quenching, which will cause deformation of the profile, such as flatness, bending and twisting in the length direction, which cannot meet the use requirements of the lithium-ion battery box.

[0029] The above technical scheme can achieve the tensile strength of aluminum alloy ≥260Mpa; the yield strength of aluminum alloy ≥240MPa; the elongation after fracture of aluminum alloy ≥8% under air-cooling quenching conditions, which greatly improves the deformation caused by uneven cooling of products under high quenching cooling intensity such as mist cooling and water cooling, and greatly improves the product qualification rate.

[0030] In a second aspect, an embodiment of the present application provides a method for preparing an aluminum alloy, comprising:

[0031] The raw material is obtained by mixing the components and mass percentages of the aluminum alloy provided in the first aspect above;

[0032] The raw materials are melted, refined, degassed, deslagged, and cast to obtain aluminum alloy rods;

[0033] The aluminum alloy rod is homogenized and then cooled.

[0034] In some optional embodiments, the aluminum alloy rod is homogenized, comprising:

[0035] The aluminum alloy rod is kept at 530°C to 540°C for 7h to 9h.

[0036] Under the above-mentioned homogenization process conditions, the alloy element atoms in the aluminum alloy rod can be diffused to eliminate or reduce the heterogeneity of the chemical composition and organization within the crystal; the internal organization of the aluminum alloy rod can be improved, the residual stress of the aluminum alloy rod can be eliminated or reduced, the mechanical processing performance of the aluminum alloy rod can be improved, and at the same time, the plasticity can be improved, the deformation resistance can be reduced, and the hot processing performance of the aluminum alloy rod can be improved.

[0037] In some optional embodiments, cooling the aluminum alloy rod comprises:

[0038] The aluminum alloy rod is cooled by wind and mist to less than 250°C and then water-cooled to room temperature.

[0039] Under the above cooling process conditions, the aluminum alloy rod structure and dendrite segregation can be eliminated, the undissolved non-equilibrium compounds between grains can be dissolved, and the multiphase crystalline compounds on the grain boundaries of the aluminum alloy rod can be basically diffused evenly, so that the composition and structure of the aluminum alloy rod can be homogenized.

[0040] In some optional embodiments, the method for preparing the aluminum alloy further comprises:

[0041] The cooled aluminum alloy rod is heated, extruded, quenched by strong wind, stretched and straightened, and sawed to obtain aluminum profiles;

[0042] The temperature of strong air cooling quenching is controlled at 500℃-530℃; the minimum quenching cooling intensity is 5℃ / s.

[0043] In the above technical solution, the aluminum alloy rod can be processed into a profile after being quenched by air cooling; compared with conventional water cooling or mist cooling quenching; the above technical solution can improve the deformation caused by uneven cooling of the product under high quenching cooling intensity such as mist cooling and water cooling, greatly improve the product qualification rate, and can be better applied to the box of lithium-ion batteries.

[0044] In a third aspect, an embodiment of the present application provides a box for packaging batteries, wherein the box for packaging batteries comprises the aluminum alloy of the aforementioned second aspect.

[0045] In a fourth aspect, an embodiment of the present application provides a battery, the battery comprising the box for encapsulating the battery provided in the third aspect.

[0046] In a fifth aspect, an embodiment of the present application provides an electrical device, which includes the battery provided in the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0049] Figure 2 An exploded view of a battery provided for some embodiments of the present application;

[0050] Figure 3 for Figure 2 An exploded view of a battery cell is shown;

[0051] Figure 4 A schematic diagram of a partial structure of an electrode assembly provided in some embodiments of the present application;

[0052] Figure 5 Schematic diagram of the structure of the tensile specimen provided for the tensile test of this application;

[0053] Figure 6 Schematic diagram of the structure of the trial mold provided for the extrusion test of this application.

[0054] icon:

[0055] Vehicles 1000;

[0056] Battery 100; Controller 200; Motor 300;

[0057] Box body 10; first part 11; second part 12; accommodating space 13;

[0058] Battery cell 20; housing 21; electrode assembly 22; electrode terminal 23; pressure relief structure 24;

[0059] Shell 211; cover 212; positive electrode sheet 221; negative electrode sheet 222; isolation film 223;

[0060] Positive electrode current collector 2211; Positive electrode active material layer 2212;

[0061] Negative electrode current collector 2221 ; negative electrode active material layer 2222 . DETAILED DESCRIPTION

[0062] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0064] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0065] In the description of the embodiments of the present application, the orientations or positional relationships indicated by the technical terms "inside" and "outside" are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0066] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0067] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0068] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the heights, lengths, widths, and other dimensions of the various components in the embodiments of the present application shown in the drawings, as well as the overall heights, lengths, widths, and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0069] Common aluminum alloys, such as 6063 aluminum alloy, 6082 aluminum alloy, and 6061 aluminum alloy, often cannot simultaneously meet the structural tensile strength performance requirements and extrusion performance requirements when used in lithium-ion battery packaging boxes; or some aluminum alloys are too expensive, limiting their industrial application.

[0070] The present application embodiment provides an aluminum alloy, the composition and mass percentage of the aluminum alloy are:

[0071] Si 0.45%-0.55%; Fe≤0.25%; Cu 0.10%-0.16%; Mn≤0.05%; Mg0.45%-0.55%; Cr≤0.05%; Zn≤0.05%; Ti≤0.05%; the balance is Al and unavoidable impurities.

[0072] In the above technical solution, by controlling the contents of Si, Mg, Cu, etc. within the above ranges, the aluminum alloy has medium strength, low quenching sensitivity, and good extrusion performance that can be used in industrial production. In addition, the alloy has a low cost and can obtain medium strength at a low cost; thus, it can be applied to parts of the lithium-ion battery box structure with low strength requirements, such as side panels, end panels, etc., thereby greatly reducing costs.

[0073] Furthermore, Mn and Cr are elements that can significantly increase the quenching sensitivity of the alloy. In the above technical solution, the mass percentages of Mn and Cr are strictly controlled to control Mn≤0.05%; Cr≤0.05%, which can effectively reduce the quenching sensitivity of the alloy.

[0074] The alloy is highly sensitive to quenching and requires water cooling or mist cooling to ensure quenching strength. This will lead to uneven distribution of residual stress generated during quenching and deformation of the profile, such as flatness, bending and twisting in the length direction, which cannot meet the product's use requirements.

[0075] The above technical solution, by reducing the quenching sensitivity of aluminum alloy, can realize quenching by air cooling, which greatly improves the problems of uneven residual stress distribution and profile deformation caused by conventional water cooling or mist cooling quenching, and improves the product qualification rate.

[0076] Furthermore, adding an appropriate amount of Cu element can improve the solid solution strengthening effect of the alloy and improve the mechanical properties of the product. After research, in the above technical solution, controlling the mass percentage of Cu element at 0.10%-0.16% can effectively improve the mechanical properties of the product, so that the aluminum alloy product has medium-strength mechanical properties, making the tensile strength of the aluminum alloy ≥260Mpa; the yield strength of the aluminum alloy ≥240MPa; the elongation of the aluminum alloy after fracture ≥8%. This aluminum alloy can be well applied to parts of the lithium-ion battery box with low structural strength requirements, such as side panels, end panels, etc., thereby greatly reducing costs; while meeting the structural mechanical strength requirements.

[0077] The box for packaging batteries provided in the present application comprises the aforementioned aluminum alloy. The box using this aluminum alloy can simultaneously meet the tensile strength performance requirements and extrusion performance requirements of the battery box structure; at the same time, the aluminum alloy has a low cost and can be better applied in industrial applications, especially suitable for boxes with low box strength requirements or parts of the box structure with low strength requirements, such as side panels and end panels, further reducing costs, thereby greatly promoting industrial applications.

[0078] The battery provided in the present application includes the aforementioned housing, and the battery has good comprehensive performance.

[0079] An embodiment of the present application provides an electrical device, comprising the aforementioned battery.

[0080] For the convenience of description, the following embodiments are described by taking a lithium-ion battery according to an embodiment of the present application as an example.

[0081] See also Figure 1 , Figure 1 A schematic diagram of the structure of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0082] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0083] In the present application, the battery 100 may refer to a physical module including a battery cell, or a single physical module including multiple battery cells 20 to provide a higher voltage and capacity. The battery 100 may be in the form of a battery module or a battery pack. The battery 100 may include a housing 10 for encapsulating one or more battery cells 20. The housing 10 may prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells 20.

[0084] See also Figure 2 , Figure 2 An exploded view of a battery 100 provided in some embodiments of the present application, the battery 100 includes a housing 10 and a battery cell 20, and the battery cell 20 is accommodated in the housing 10. In the battery 100, the battery cell 20 may be one or more. If there are multiple battery cells 20, the multiple battery cells 20 may be connected in series, in parallel, or in mixed connection. Mixed connection means that multiple battery cells 20 are both connected in series and in parallel. Multiple battery cells 20 may be directly connected in series, in parallel, or in mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the housing 10. Alternatively, multiple battery cells 20 may be first connected in series, in parallel, or in mixed connection to form a module, and the multiple modules may be connected in series, in parallel, or in mixed connection to form a whole, and then accommodated in the housing 10. The battery 100 may also include other structures. For example, multiple battery cells 20 may be electrically connected through a busbar component to achieve parallel, series, or mixed connection of multiple battery cells 20.

[0085] Each battery cell 20 may be a lithium-ion battery, such as a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto.

[0086] See also Figure 3 , Figure 3 for Figure 2 The exploded view of the battery cell 20 is shown. The battery cell 20 refers to the smallest unit constituting the battery 100. The battery cell 20 may include a housing 21, an electrode assembly 22 and an electrolyte, and the electrode assembly 22 and the electrolyte are both contained in the housing 21.

[0087] The housing 21 may include a shell 211 and a cover 212. The shell 211 is a component used to cooperate with the cover 212 to form an internal sealed space of the battery cell 20, wherein the formed sealed space can be used to accommodate the electrode assembly 22, electrolyte and other components. The cover 212 refers to a component that covers the opening of the shell 211 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the cover 212 can be adapted to the shape of the shell 211 to cooperate with the shell 211, and the cover 212 may also be provided with functional components such as electrode terminals 23 and pressure relief structures 24. A sealing ring may be configured between the opening of the shell 211 and the cover 212 to achieve sealing between the shell 211 and the cover 212.

[0088] The shell 211 and the cover 212 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shapes of the shell 211 and the cover 212 can be determined according to the specific shape and size of the electrode assembly 22. The shell 211 and the cover 212 can be made of various materials, such as but not limited to metals such as copper, iron, aluminum, stainless steel, and aluminum alloy. The sealing ring can be made of various materials, such as but not limited to PP (polypropylene), PC (polycarbonate), PET (polyethylene terephthalate) and other materials that are resistant to electrolyte corrosion, high toughness and fatigue resistance. A coating can be formed on the outer surface of the shell 211, and the material of the coating can be various, such as but not limited to corrosion-resistant materials such as Ni and Cr.

[0089] See also Figure 4 The electrode assembly 22 may be composed of a positive electrode sheet 221, a negative electrode sheet 222, and a separator 223. The separator 223 is located between the positive electrode sheet 221 and the negative electrode sheet 222 to play a role of isolation. The electrode assembly 22 may be a winding structure or a laminated structure, but the embodiments of the present application are not limited thereto.

[0090] See also Figure 4 The positive electrode sheet 221 includes a positive electrode current collector 2211 and a positive electrode active material layer 2212. Taking the lithium-ion battery cell 20 as an example, the material of the positive electrode current collector 2211 can be aluminum. The positive electrode active material layer 2212 includes a positive electrode active material.

[0091] Please continue to see Figure 2 The box 10 is used to accommodate the battery cell 20, and the box 10 can be of various structures. In some embodiments, the box 10 may include a first part 11 and a second part 12, and the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a storage space 13 for accommodating the battery cell 20. The second part 12 may be a hollow structure with one end open, and the first part 11 is a plate-like structure, and the first part 11 covers the open side of the second part 12 to form a box 10 with a storage space 13; the first part 11 and the second part 12 may also be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12 to form a box 10 with a storage space 13. Of course, the first part 11 and the second part 12 may be of various shapes, such as a cylinder, a cuboid, etc.

[0092] In some embodiments of the present application, the material of the box body 10 is aluminum alloy.

[0093] Furthermore, in some embodiments of the present application, an aluminum alloy is provided, wherein the aluminum alloy comprises the following components in terms of mass percentage:

[0094] Si 0.51-0.59; Fe≤0.20; Cu 0.16-0.23; Mn≤0.03; Mg 0.52-0.59; Cr≤0.03; Zn≤0.03; Ti≤0.05; rare earth elements 0.11-0.15; other unavoidable impurities≤0.10; the balance is Al.

[0095] The present application embodiment provides an aluminum alloy, the composition and mass percentage of the aluminum alloy are:

[0096] Si 0.45%-0.55%; Fe≤0.25%; Cu 0.10%-0.16%; Mn≤0.05%; Mg0.45%-0.55%; Cr≤0.05%; Zn≤0.05%; Ti≤0.05%; the balance is Al and unavoidable impurities.

[0097] In the above technical solution, by controlling the contents of Si, Mg, Cu, etc. within the above ranges, the aluminum alloy has medium strength, low quenching sensitivity, and good extrusion performance that can be applied in industrial production. In addition, the alloy has a low cost and can obtain medium strength at a low cost; thus, it can be applied to lithium-ion battery boxes with low strength requirements; or parts with low structural strength requirements, such as side panels, end panels, etc., thereby greatly reducing costs and promoting industrial applications.

[0098] Furthermore, Mn and Cr are elements that can significantly increase the quenching sensitivity of the alloy. In the above technical solution, the mass percentages of Mn and Cr are strictly controlled to control Mn≤0.05%; Cr≤0.05%, which can effectively reduce the quenching sensitivity of the alloy.

[0099] The alloy is highly sensitive to quenching and requires water cooling or mist cooling to ensure quenching strength. This will lead to uneven distribution of residual stress generated during quenching and deformation of the profile, such as flatness, bending and twisting in the length direction, which cannot meet the product's use requirements.

[0100] The above technical solution, by reducing the quenching sensitivity of aluminum alloy, can realize quenching by air cooling, which greatly improves the problems of uneven residual stress distribution and profile deformation caused by conventional water cooling or mist cooling quenching, and improves the product qualification rate.

[0101] Furthermore, adding an appropriate amount of Cu element can improve the solid solution strengthening effect of the alloy and improve the mechanical properties of the product. After research, in the above technical solution, controlling the mass percentage of Cu element at 0.10%-0.16% can effectively improve the mechanical properties of the product, so that the aluminum alloy product has medium-strength mechanical properties, making the tensile strength of the aluminum alloy ≥260Mpa; the yield strength of the aluminum alloy ≥240MPa; the elongation of the aluminum alloy ≥8%. This aluminum alloy can be well applied to lithium-ion battery boxes with low strength requirements; or parts of the box structure with low strength requirements, such as side panels, end panels, etc., thereby greatly reducing costs; while meeting the structural mechanical strength requirements.

[0102] Further, in some embodiments of the present application, the composition and mass percentage of the aluminum alloy are:

[0103] Si 0.45%-0.50%; Fe≤0.25%; Cu 0.10%-0.15%; Mn≤0.05%; Mg0.45%-0.51%; Cr≤0.05%; Zn≤0.05%; Ti≤0.05%; the balance is Al and unavoidable impurities.

[0104] In the above technical solution, the content of each element is further strictly controlled within the above range to obtain an aluminum alloy with better comprehensive performance.

[0105] For example, in some embodiments of the present application, the composition and mass percentage of the above-mentioned aluminum alloy are:

[0106] Si 0.46%, 0.47%, 0.48%, 0.49%, 0.50%, 0.51%, 0.52%, 0.53% or 0.54%;

[0107] Fe≤0.25%; Fe≤0.24%; Fe≤0.23%; Fe≤0.22%; Fe≤0.21% or Fe≤0.20%;

[0108] Cu 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15% or 0.16%;

[0109] Mn≤0.05%; Mn≤0.04%; Mn≤0.03%; Mn≤0.02%; Mn≤0.01%;

[0110] Mg 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, 0.50%, 0.51%, 0.52%, 0.53%, 0.54% or 0.55%;

[0111] Cr≤0.05%; Cr≤0.04%; Cr≤0.03%; Cr≤0.02% or Cr≤0.01%;

[0112] Zn≤0.05%; Zn≤0.04%; Zn≤0.03%; Zn≤0.02% or Zn≤0.01%;

[0113] Ti≤0.05%; Ti≤0.04%; Ti≤0.03%; Ti≤0.02% or Ti≤0.01%;

[0114] The balance is Al and inevitable impurities.

[0115] Further, in some embodiments of the present application, the mass ratio of Mg to Si is 0.9-1.0.

[0116] In the above technical solution, the mass ratio of Mg to Si is controlled to be 0.9-1.0, and the strength, quenching sensitivity and extrusion performance of the aluminum alloy can be better controlled within the target range.

[0117] Further optionally, in some embodiments of the present application, the mass ratio of Mg to Si is 0.9-1.0.

[0118] Illustratively, in some embodiments of the present application, the mass ratio of Mg to Si is 0.9 or 1.0.

[0119] In the above technical solution, the mass ratio of Mg and Si affects the content of the strengthening phase Mg5Si6 of the aluminum alloy, thereby affecting the precipitation strengthening effect of the aluminum alloy; affecting the mechanical strength and extrusion performance of the aluminum alloy. When the content of the alloy strengthening phase Mg5Si6 is too low, the mechanical strength of the aluminum alloy is low; when the content of the alloy strengthening phase Mg5Si6 is too high, the extrusion performance of the aluminum alloy is low. In order to simultaneously meet the tensile strength target and extrusion performance of the aluminum alloy of this application; and taking into account the cost of the aluminum alloy, the above technical solution sets the mass ratio of Mg and Si within the above range, which is conducive to obtaining the tensile strength of the aluminum alloy ≥260Mpa; the yield strength of the aluminum alloy ≥240MPa; the elongation of the aluminum alloy ≥8%; and the aluminum alloy has better extrusion performance, which can meet the industrial application of lithium-ion battery packaging boxes.

[0120] Furthermore, in some embodiments of the present application, in terms of mass percentage, Mn+Mg+Zn≤0.55%.

[0121] For aluminum alloys, Mg is a strengthening element. In aluminum alloys, Mg can form Mg2Si phase. The Mg2Si generated first in the aluminum alloy will dissolve into α-Al, and will precipitate from the α-Al solid solution after quenching and aging, and will be highly dispersed in the aluminum matrix, so that the alloy is strengthened. However, when the Mg content is too high and the generated Mg2Si cannot be completely dissolved in the matrix aluminum, the excess Mg2Si will be a coarse brittle phase. This part of the excess Mg2Si phase not only has no strengthening effect, but will cause the elongation of the alloy to drop rapidly.

[0122] Adding Zn and Mg into aluminum alloy at the same time can form Mg2Zn strengthening phase, which can significantly improve the strength of aluminum alloy.

[0123] Mn can inhibit the harm of Fe and reduce the harm of iron-containing phases, but manganese has a tendency to segregate.

[0124] The above technical scheme, taking into account the mechanical strength performance target, extrusion performance target and alloy cost of aluminum alloy, sets Mn+Mg+Zn≤0.55%, which is conducive to obtaining the tensile strength of aluminum alloy ≥260Mpa; the yield strength of aluminum alloy ≥240MPa; the elongation after fracture of aluminum alloy ≥8%; and the aluminum alloy has better extrusion performance, which can meet the industrial application of lithium-ion battery packaging box.

[0125] Furthermore, Cu can react with the primary α-Al phase in the alloy to generate CuAl2 strengthening phase, and precipitate second phase particles such as GP zone, coherent θ phase", semi-coherent phase θ', incoherent equilibrium phase θ during the aging process to strengthen the matrix. The θ phase" has the best strengthening effect. After aging, these strengthening phases are dispersed in the aluminum matrix, hindering the movement of dislocations through the dislocation pinning effect, thereby improving the strength of the aluminum alloy.

[0126] In the above technical scheme, the Cu content in the aluminum alloy formula is controlled to be 0.10wt.%-0.16wt.%, which can cooperate with other elements to obtain the tensile strength of the aluminum alloy ≥260Mpa; the yield strength of the aluminum alloy ≥240MPa; the elongation after fracture of the aluminum alloy ≥8%; and the aluminum alloy has better extrusion performance, which can meet the industrial application of lithium-ion battery packaging boxes.

[0127] For example, in some embodiments of the present application, the aluminum alloy formula is as follows, calculated by mass percentage:

[0128] Si 0.46%, Fe≤0.25%; Cu 0.11%, Mn≤0.05%, Mg 0.46%, Cr≤0.05%, Zn≤0.05%; Ti≤0.05%; other unavoidable impurities≤0.10%; the balance is Al.

[0129] For example, in some embodiments of the present application, the aluminum alloy formula is as follows, calculated by mass percentage:

[0130] Si 0.47%, Fe≤0.25%; Cu 0.13%, Mn≤0.05%, Mg 0.48%, Cr≤0.05%, Zn≤0.05%; Ti≤0.05%; other unavoidable impurities≤0.10%; the balance is Al.

[0131] For example, in some embodiments of the present application, the aluminum alloy formula is as follows, calculated by mass percentage:

[0132] Si 0.50%, Fe≤0.25%; Cu 0.15%, Mn≤0.05%, Mg 0.51%, Cr≤0.05%, Zn≤0.05%; Ti≤0.05%; other unavoidable impurities≤0.10%; the balance is Al.

[0133] For example, in some embodiments of the present application, the aluminum alloy formula is as follows, calculated by mass percentage:

[0134] Si 0.53%, Fe≤0.25%; Cu 0.14%, Mn≤0.05%, Mg 0.51%, Cr≤0.05%, Zn≤0.05%; Ti≤0.05%; other unavoidable impurities≤0.10%; the balance is Al.

[0135] For example, in some embodiments of the present application, the aluminum alloy formula is as follows, calculated by mass percentage:

[0136] Si 0.49%, Fe≤0.25%; Cu 0.11%, Mn≤0.05%, Mg 0.49%, Cr≤0.05%, Zn≤0.05%; Ti≤0.05%; other unavoidable impurities≤0.10; the balance is Al.

[0137] Furthermore, in some embodiments of the present application, the unavoidable impurities are ≤0.10% by mass.

[0138] Furthermore, in some embodiments of the present application, when the unavoidable impurities include multiple components, the mass percentage of a single component is less than or equal to 0.03%.

[0139] In the above technical solution, the mass percentage of impurities of a single component is controlled to be less than or equal to 0.03%, which can avoid the aggregation of a single component and stabilize the performance of the aluminum alloy.

[0140] Further, in some embodiments of the present application, the aluminum alloy has the following characteristics under the condition of air-cooling quenching with a cooling intensity of 5°C / s:

[0141] (a) The tensile strength of aluminum alloy is ≥260Mpa;

[0142] (b) The yield strength of aluminum alloy is ≥240MPa;

[0143] (c) The elongation after fracture of the aluminum alloy is ≥8%.

[0144] The higher the quenching cooling intensity, the better the tensile strength, yield strength and elongation of the aluminum alloy.

[0145] In the above technical solution, the aluminum alloy can have the goals of tensile strength ≥ 260 MPa, yield strength ≥ 240 MPa, and elongation after fracture ≥ 8% under the condition of air-cooling quenching with a cooling intensity of 5°C / s.

[0146] Water cooling or mist cooling quenching will cause uneven distribution of residual stress generated during quenching, which will cause deformation of the profile, such as flatness, bending and twisting in the length direction, which cannot meet the use requirements of the lithium-ion battery box.

[0147] The above technical scheme can achieve the tensile strength of aluminum alloy ≥260Mpa; the yield strength of aluminum alloy ≥240MPa; the elongation after fracture of aluminum alloy ≥8% under air-cooling quenching conditions, which greatly improves the deformation caused by uneven cooling of products under high quenching cooling intensity such as mist cooling and water cooling, and greatly improves the product qualification rate.

[0148] Further, in some embodiments of the present application, the present application provides a method for preparing an aluminum alloy, comprising:

[0149] The raw material is obtained by mixing the components and mass percentages of the aluminum alloy provided in the first aspect above;

[0150] The raw materials are melted, refined, degassed, deslagged, and cast to obtain aluminum alloy rods;

[0151] The aluminum alloy rod is homogenized and then cooled.

[0152] Further, in some embodiments of the present application, the aluminum alloy rod is homogenized, comprising:

[0153] The aluminum alloy rod is kept at 560°C to 570°C for 7h to 9h.

[0154] Under the above-mentioned homogenization process conditions, the alloy element atoms in the aluminum alloy rod can be diffused to eliminate or reduce the heterogeneity of the chemical composition and organization within the crystal; the internal organization of the aluminum alloy rod can be improved, the residual stress of the aluminum alloy rod can be eliminated or reduced, the mechanical processing performance of the aluminum alloy rod can be improved, and at the same time, the plasticity can be improved, the deformation resistance can be reduced, and the hot processing performance of the aluminum alloy rod can be improved.

[0155] Further optionally, in some embodiments of the present application, the aluminum alloy rod is homogenized, comprising:

[0156] The aluminum alloy rod is kept at 561°C to 569°C for 7.1h to 8.9h.

[0157] For example, in some embodiments of the present application, the aluminum alloy rod is homogenized, comprising:

[0158] The aluminum alloy rod is kept at 560°C, 561°C, 562°C, 563°C, 564°C, 565°C, 566°C, 567°C, 568°C, 569°C or 570°C for 7h, 7.5h, 8h, 8.5h or 9h.

[0159] Further, in some embodiments of the present application, cooling the aluminum alloy rod comprises:

[0160] The aluminum alloy rod is cooled by wind and mist to less than 250°C and then water-cooled to room temperature.

[0161] Under the above cooling process conditions, the aluminum alloy rod structure and dendrite segregation can be eliminated, the undissolved non-equilibrium compounds between grains can be dissolved, and the multiphase crystalline compounds on the grain boundaries of the aluminum alloy rod can be basically diffused evenly, so that the composition and structure of the aluminum alloy rod can be homogenized.

[0162] Further optionally, in some embodiments of the present application, cooling the aluminum alloy rod comprises:

[0163] The aluminum alloy rod is cooled to less than 249°C by wind and mist and then water cooled to room temperature.

[0164] Exemplarily, in some embodiments of the present application, cooling the aluminum alloy rod comprises:

[0165] The aluminum alloy rod is cooled by wind and mist to <248°C, <247°C, <246°C, <245°C, <244°C, <243°C or <240°C and then water-cooled to room temperature.

[0166] Furthermore, in some embodiments of the present application, the method for preparing the aluminum alloy further includes:

[0167] The cooled aluminum alloy rod is heated, extruded, quenched by strong wind, stretched and straightened, and sawed to obtain aluminum profiles;

[0168] The temperature of strong air cooling quenching is controlled at 500℃-530℃; the minimum quenching cooling intensity is 5℃ / s.

[0169] In the above technical solution, the aluminum alloy rod can be processed into a profile after being quenched by air cooling; compared with conventional water cooling or mist cooling quenching; the above technical solution can improve the deformation caused by uneven cooling of the product under high quenching cooling intensity such as mist cooling and water cooling, greatly improve the product qualification rate, and can be better applied to the box of lithium-ion batteries.

[0170] Further optionally, in some embodiments of the present application, the method for preparing the aluminum alloy further includes:

[0171] The cooled aluminum alloy rod is heated, extruded, quenched by strong wind, stretched and straightened, and sawed to obtain aluminum profiles;

[0172] The temperature of strong air cooling quenching is controlled at 501℃-529℃; the minimum quenching cooling intensity is 5℃ / s.

[0173] Illustratively, in some embodiments of the present application, the method for preparing the aluminum alloy further includes:

[0174] The cooled aluminum alloy rod is heated, extruded, quenched by strong wind, stretched and straightened, and sawed to obtain aluminum profiles;

[0175] The temperature of strong air cooling quenching is controlled at 505℃, 508℃, 510℃, 515℃, 520℃, 525℃ or 528℃.

[0176] Some specific embodiments are listed below to better illustrate the present application.

[0177] Examples 1-10

[0178] An aluminum alloy is provided, and the formula is shown in Table 1.

[0179] Comparative Example 1-Comparative Example 5

[0180] An aluminum alloy is provided, and the formula is shown in Table 1.

[0181] Table 1 Aluminum alloy formula (wt.%)

[0182]

[0183]

[0184]

Preparation of aluminum alloy

[0185] (1) preparing ingredients according to the formula of each embodiment or comparative example to obtain raw materials;

[0186] (2) melting, refining, degassing, deslagging, and casting the raw materials to obtain aluminum alloy rods;

[0187] (3) The aluminum alloy rod is homogenized and then cooled. The homogenization process is carried out at a holding temperature of 560°C for 7 hours. The cooling process is carried out by strong wind cooling to <250°C and then water cooling to room temperature.

[0188] (4) The aluminum alloy rod is heated, extruded, quenched by online strong air cooling, stretched and straightened, and sawed to obtain an aluminum profile. The quenching temperature is 500°C; the minimum quenching cooling intensity is 5°C / s.

[0189] (5) The aluminum profile is artificially aged to obtain a high-strength aluminum profile.

[0190]

Aluminum alloy performance test

[0191] 1. Tensile test

[0192] Test method: Refer to GB / T 16865-2013 "Test specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products" to process the test specimens of each embodiment or comparative example, and finally process the test specimens into standard tensile specimens. The size and shape of the standard tensile specimens are as follows: Figure 5 shown.

[0193] During the test, a Sansi CMT5504 model 50KN tensile testing machine was used at room temperature. Under the same conditions, five specimens were used to stretch each embodiment or comparative example, and the average value of the five specimens was finally used as the experimental data.

[0194] The yield strength, tensile strength and elongation after fracture are obtained by reading the equipment and calculating the experimental data.

[0195] The test results are shown in Table 2.

[0196] 2. Extrusion test

[0197] (1) Trial machine: 2200T, extrusion barrel diameter

[0198] (2) Trial mold: HP19 project side beam (such as Figure 6 ), cross-sectional area 1440.92mm 2 , extrusion ratio 24.27;

[0199] (3) Test aluminum rod: The samples of each embodiment or comparative example are prepared as follows: Aluminum rods;

[0200] (4) Extrusion process parameters

[0201] ①Pressure remaining length: 30mm

[0202] ②Mold temperature: 485℃, insulation time 5h

[0203] ③Aluminum rod temperature: head 490℃, tail 470℃ (lead rod temperature increased by 10℃ on this basis) ④Extrusion speed: 1.8mm / s

[0204] ⑤Quenching temperature: 500℃

[0205] ⑥Quenching method: strong air cooling (upper and lower 100%, left and right 30% air volume)

[0206] ⑦Quenching temperature: ≤200℃

[0207] ⑧Extrusion length: 15m, elongation: 0.9% (stretching length 130mm)

[0208] ⑨ Sawing head and tail: the guide rod is directly scrapped, the rest of the cutting head ≥ 2m, cutting tail ≥ 2m

[0209] ⑩Aging plan: Samples are aged at 175℃*8h, and fixed-length samples are temporarily retained without aging.

[0210] The extrusion breakthrough pressure of each example or comparative example sample was read by the device.

[0211] The extrusion breakthrough pressure was used to characterize the extrusion performance of each embodiment and comparative example.

[0212] The smaller the extrusion breakthrough pressure, the better the extrusion property.

[0213] The test results are shown in Table 2.

[0214] Table 2

[0215]

[0216]

[0217] From the test results in Table 2 above, we can see that:

[0218] The aluminum alloy of the embodiment of the present application can simultaneously meet the following objectives:

[0219] (a) The tensile strength of aluminum alloy is ≥260Mpa;

[0220] (b) The yield strength of aluminum alloy is ≥240MPa;

[0221] (c) The elongation after fracture of the aluminum alloy is ≥8%.

[0222] (d) The extrusion breakthrough pressure of aluminum alloy is ≤195Bar.

[0223] Comparative Examples 1 to 4 cannot simultaneously meet the objectives that the above embodiments of the present application intend to achieve.

[0224] The formula of Comparative Example 1 is the commonly used 6061 aluminum alloy, which has a relatively low yield strength and an extrusion breakthrough pressure far exceeding the target of this application; it cannot meet the requirements of this application.

[0225] The formula of Comparative Example 2 is the commonly used 6082 aluminum alloy, and its extrusion breakthrough pressure far exceeds the target of this application; it cannot meet the requirements of this application.

[0226] The formula of comparative example 3 is the commonly used 6063 aluminum alloy, and its tensile strength and yield strength are far lower than the target of this application; it cannot meet the requirements of this application.

[0227] The formulas of Comparative Examples 4 and 5 are not in the aluminum alloy of the present application, and their tensile strength and yield strength are both lower than the target values ​​of the present application; the elongation after fracture of Comparative Example 5 is also lower than the target of the present application; both Comparative Examples 4 and 5 cannot meet the requirements of the present application; the extrudable breakthrough pressures of Comparative Examples 4 and 5 far exceed the target of the present application; and cannot meet the requirements of the present application.

[0228] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

Claims

1. An aluminum alloy, characterized in that: The composition and mass percentage of the aluminum alloy are: Si 0.45%-0.55%; Fe≤0.25%; Cu 0.10%-0.16%; Mn≤0.05%; Mg0.45%-0.55%; Cr≤0.05%; Zn≤0.05%; Ti≤0.05%; the balance is Al and unavoidable impurities.

2. The aluminum alloy according to claim 1, characterized in that The composition and mass percentage of the aluminum alloy are: The Si is 0.45%-0.50%; the Fe is ≤0.25%; the Cu is 0.10%-0.15%; the Mn is ≤0.05%; the Mg is 0.45%-0.51%; the Cr is ≤0.05%; the Zn is ≤0.05%; the Ti is ≤0.05%; and the balance is Al and unavoidable impurities.

3. The aluminum alloy according to claim 1 or 2, characterized in that: The mass ratio of the Mg to the Si is 0.81-1.22; optionally, the mass ratio of the Mg to the Si is 0.9-1.

0.

4. The aluminum alloy according to any one of claims 1 to 3, characterized in that: In terms of mass percentage, the Mn+Mg+Zn≤0.55%.

5. The aluminum alloy according to any one of claims 1 to 4, characterized in that: Measured in mass percentage, the unavoidable impurities are ≤0.10%.

6. The aluminum alloy according to any one of claims 1 to 5, characterized in that: When the unavoidable impurities include multiple components, the mass percentage of a single component is less than or equal to 0.03%.

7. The aluminum alloy according to any one of claims 1 to 6, characterized in that: The aluminum alloy has the following characteristics under the condition of air-cooling quenching with a cooling intensity of 5°C / s: (a) The tensile strength of the aluminum alloy is ≥260Mpa; (b) the yield strength of the aluminum alloy is ≥240 MPa; (c) The elongation after fracture of the aluminum alloy is ≥8%.

8. A method for preparing an aluminum alloy, characterized in that: include: The raw material is obtained by mixing the components and mass percentages of the aluminum alloy according to any one of claims 1 to 6; The raw materials are melted, refined, degassed, deslagged, and cast to obtain aluminum alloy rods; The aluminum alloy rod is homogenized and then cooled.

9. The method for preparing an aluminum alloy according to claim 8, characterized in that: The step of homogenizing the aluminum alloy rod comprises: The aluminum alloy rod is kept at 530° C. to 540° C. for 7 h to 9 h.

10. The method for preparing an aluminum alloy according to claim 8, characterized in that: The step of cooling the aluminum alloy rod comprises: The aluminum alloy rod is cooled to less than 250° C. by strong wind and then water-cooled to room temperature.

11. The method for preparing an aluminum alloy according to claim 8, characterized in that: The method for preparing the aluminum alloy further comprises: The cooled aluminum alloy rod is heated, extruded, quenched by strong wind, stretched and straightened, and sawed to obtain an aluminum profile; The temperature of the strong air cooling quenching is controlled at 500°C-530°C; the minimum quenching cooling intensity is 5°C / s.

12. A box for packaging batteries, characterized in that: The box for packaging batteries comprises the aluminum alloy according to any one of claims 1-11.

13. A battery, characterized in that: The battery comprises the case for packaging a battery as claimed in claim 12.

14. An electrical device, characterized in that: The electrical device comprises the battery according to claim 13.

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