Aluminum alloy material, aluminum alloy structural member, preparation method of aluminum alloy structural member, battery box body, battery system, power utilization device and application

Abstract

The invention relates to an aluminum alloy material, an aluminum alloy structural part, a preparation method of the aluminum alloy structural part, a battery box body, a battery system, a power utilization device and application. The aluminum alloy material comprises the following composition elements in percentage by mass: 6%-11% of Si, 0.5%-0.9% of Cu, 0.1%-0.4% of Ti, 0.2%-0.6% of Mg, 0.25%-0.6% of Zn, 0.5%-1.1% of Mn, 0.01%-0.05% of Sr, a matrix element Al and inevitable impurity elements, the aluminum alloy material comprises or does not comprise an Al2Cu phase, and the mass fraction of the Al2Cu phase in the aluminum alloy material can be smaller than or equal to 1.3%. The aluminum alloy material has good mechanical properties and excellent corrosion resistance, can be used as a main body material of the battery box body, and is beneficial to prolonging the service life of the battery box body.

Description

Technical Field

[0001] This application relates to the technical field of aluminum alloy materials, further to the technical field of battery box materials, and even further to aluminum alloy materials, aluminum alloy structural parts and their preparation methods, battery boxes, battery systems, electrical devices and applications. Background Art

[0002] The statements herein only provide background information related to this application and do not necessarily constitute prior art.

[0003] The battery box is a key component of the battery and plays an important role in protecting the battery. For a battery containing electrolyte, it is required not only that the battery box has good mechanical properties to reduce the damage degree of the battery when it is impacted, but also that the battery box has a certain corrosion resistance to extend the service life of the battery. At present, it is necessary to further improve the corrosion resistance of aluminum alloy materials. Summary of the Invention

[0004] In view of the above problems, this application provides an aluminum alloy material, an aluminum alloy structural part and their preparation methods, a battery box, a battery system, an electrical device and an application. This aluminum alloy material has good mechanical properties and excellent corrosion resistance, and can be used as the main material of the battery box, which is beneficial to extending the service life of the battery box.

[0005] In the first aspect, this application provides an aluminum alloy material, which includes silicon (Si) element, copper (Cu) element, titanium (Ti) element, magnesium (Mg) element, zinc (Zn) element, manganese (Mn) element, strontium (Sr) element, matrix element Al and inevitable impurity elements, and there is no Al 2 Cu phase or the content is less, for example Al 2 The mass fraction of the Cu phase in this aluminum alloy material is relatively low (such as ≤1.3%).

[0006] In some embodiments, an aluminum alloy material is provided. By mass percentage, the aluminum alloy material includes the following constituent elements: 6% - 11% of Si, 0.5% - 0.9% of Cu, 0.1% - 0.4% of Ti, 0.2% - 0.6% of Mg, 0.25% - 0.6% of Zn, 0.5% - 1.1% of Mn, 0.01% - 0.05% of Sr, matrix element Al and inevitable impurity elements;

[0007] Among them, the aluminum alloy material includes or does not include Al 2 Cu phase, and the mass fraction of the Al 2 Cu phase in the aluminum alloy material is ≤1.3%.

[0008] The aluminum alloy material has aluminum (Al) as the matrix element, including silicon (Si) element, copper (Cu) element, titanium (Ti) element, magnesium (Mg) element, zinc (Zn) element, manganese (Mn) element and strontium (Sr) element, by controlling the composition elements of the aluminum alloy material within the aforementioned content ranges. The matrix element Al in the aluminum alloy material forms an α-Al matrix phase, and the matrix phase is mainly distributed in a near equiaxed crystal form. The Si element can form an Al-Si eutectic phase with the α-Al matrix phase, which can provide good basic mechanical properties. The introduction of the Cu element may form a bone-shaped or needle-shaped Al 2 Cu phase, Al 2 The Cu phase has a certain strengthening effect; although the increase in Cu content is beneficial to improving the mechanical strength of the material, such as combining with impurities to change the morphology of the impurity phase and thus reducing the damage of the impurity phase to the mechanical properties; however, a high content of Cu element is likely to cause a decrease in the corrosion resistance of the aluminum alloy material and is also likely to reduce the elongation of the aluminum alloy material. Al 2 The potential of the Cu phase is relatively positive, and the potential of the matrix phase with a higher Cu content is also relatively positive. At this time, the matrix phase with a lower Cu content will act as the cathode phase, together with the nearby Cu-rich matrix phase and Al 2 The Cu phase forms an electrochemical microcell locally, causing the matrix phase part of the Cu-poor solid solution to be continuously corroded. Al 2 The content of Cu is basically linearly related to the Cu content. By designing a relatively low copper content, the Al 2The proportion of the Cu phase is increased to improve the corrosion resistance and elongation of the material. In addition, in the aluminum alloy material provided above, by using only a small amount of Cu element, while producing a strengthening effect, it has no adverse effect or a small impact on the corrosion resistance. By introducing Ti element, round or nearly elliptical precipitation phases can be formed, which can serve as non-spontaneous nucleation sites during crystallization, have a certain grain refinement effect, and can play a strengthening role and improve the elongation. The introduction of Mg element and Zn element can improve the strength of the aluminum alloy material by forming solid solutions and precipitation strengthening. Sr element can dissolve in the matrix phase. Sr can change the solidification process during casting, have a modification effect on the alloy phase of the aluminum alloy material, and can modify the Al-Si eutectic structure into fine fibrous shape, thereby improving the mechanical strength. Mn element can supplement the strengthening effect of Mg element and make the precipitation phase evenly distributed. In addition, the introduction of Mn element helps the demolding process during casting and can also combine with impurity elements to reduce the damage of impurity elements to the corrosion resistance of the aluminum alloy material. By designing the element composition and element content in the aluminum alloy material, the prepared aluminum alloy material can have a special microstructure. Through multiple synergistic effects among the elements, while effectively improving the corrosion resistance of the aluminum alloy material, the aluminum alloy material also has good mechanical properties, and both the mechanical strength and ductility are improved. By reasonably setting the contents of elements such as Cu element, Mg element, and Zn element, it can lay a foundation for the aluminum alloy material to have good mechanical properties such as tensile strength and hardness. By controlling the contents of Cu element, Ti element, and Sr element in the aluminum alloy material, the corrosion resistance of the aluminum alloy material can be significantly improved.

[0009] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material satisfies one or two of the following characteristics:

[0010] The mass percentage of Cu element in the aluminum alloy material is 0.5% - 0.8%;

[0011] The aluminum alloy material includes Al 2 Cu phase, and the mass fraction of the Al 2 Cu phase in the aluminum alloy material is 0.1% - 1.3%.

[0012] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material satisfies one or two of the following characteristics:

[0013] The mass percentage of Cu element in the aluminum alloy material is 0.6% - 0.8%;

[0014] The aluminum alloy material includes Al 2 Cu phase, and the Al 2The mass fraction of the Cu phase in the aluminum alloy material is 0.8% to 1.3%.

[0015] By adjusting the mass percentage of the Cu element in the aluminum alloy material, the content of the Al 2 Cu phase can be controlled. By controlling the content of the Al 2 Cu phase within the aforementioned range, it is more conducive to the aluminum alloy material obtaining good mechanical properties and excellent corrosion resistance. It is more conducive to having good mechanical strength and ductility of the aluminum alloy material while obtaining excellent corrosion resistance.

[0016] Based on any suitable implementation manner of the present application, further, in some implementation manners, the aluminum alloy material includes a fibrous Al-Si eutectic structure; the aluminum alloy material includes Al 3 Ti strengthening phase.

[0017] In the aluminum alloy material, the α-Al matrix phase and the Si phase form an Al-Si eutectic phase, and this eutectic phase is mainly distributed in the form of fine fibrous tissues between the α-Al grains, which is conducive to improving the mechanical strength of the matrix phase. The Ti element can form round or nearly elliptical Al 3 Ti precipitation phases, and these precipitation phases can serve as non-spontaneous nucleation sites during crystallization, playing a certain role in grain refinement and can play a strengthening role. In addition, the improvement of the distribution of the second-phase structure and fine grain strengthening are both conducive to improving the ductility.

[0018] Based on any suitable implementation manner of the present application, further, in some implementation manners, the aluminum alloy material satisfies one, two, or three of the following characteristics:

[0019] The mass percentage of the Si element in the aluminum alloy material is 6.5% to 11%;

[0020] The mass percentage of the Ti element in the aluminum alloy material is 0.2% to 0.4%;

[0021] The Al 3 The mass fraction of the Ti strengthening phase in the aluminum alloy material is 0.3% to 2%.

[0022] Based on any suitable implementation manner of the present application, further, in some implementation manners, the aluminum alloy material satisfies one, two, or three of the following characteristics:

[0023] The mass percentage of the Si element in the aluminum alloy material is 8% to 11%;

[0024] The mass percentage of the Ti element in the aluminum alloy material is 0.25% to 0.4%;

[0025] The Al3 The mass fraction of the Ti strengthening phase in the aluminum alloy material is 0.3% - 1%, and can be optionally 0.35% - 0.6%.

[0026] By adjusting the content of Si element, the morphology of the Al - Si eutectic structure can be adjusted, and by adjusting the content of Ti element, the content of the Al 3 Ti strengthening phase can be controlled. By adjusting one or more of these content parameters, the mechanical properties of the aluminum alloy material can be adjusted. Within the aforementioned range, it is beneficial to provide good mechanical strength while reducing the Cu content.

[0027] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material includes or does not include Mg 2 Si phase, and the mass fraction of the Mg 2 Si phase in the aluminum alloy material is ≤0.05%, and can be optionally 0%.

[0028] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material satisfies one or two or three of the following characteristics:

[0029] The mass percentage of Mg element in the aluminum alloy material is 0.3% - 0.6%;

[0030] The mass percentage of Zn element in the aluminum alloy material is 0.3% - 0.6%;

[0031] The mass ratio of Mg element and Zn element in the aluminum alloy material is 1:(1.1 - 1.3).

[0032] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material satisfies one or two of the following characteristics:

[0033] The mass percentage of Mg element in the aluminum alloy material is 0.3% - 0.5%;

[0034] The mass percentage of Zn element in the aluminum alloy material is 0.4% - 0.6%;

[0035] The mass ratio of Mg element and Zn element in the aluminum alloy material is 1:(1.1 - 1.25).

[0036] The introduction of Mg element may also generate Al 5 Cu 2 Mg 8 Si 16 phase, which can play a role in high - temperature strengthening. Mg 2 Si phase can also strengthen the aluminum alloy, but Mg2 The Si phase is a strong cathodic phase, which is likely to accelerate the corrosion of the matrix and cause damage to the corrosion resistance of the aluminum alloy material. In the aluminum alloy material system provided in this application, when the Mg content exceeds about 1.2 wt%, Mg 2 Si phase begins to precipitate. By regulating the Mg content, the precipitation behavior of the Mg 2 Si phase can be regulated, so that the Mg 2 Si phase that appears in the intermediate process is dissolved, so that there is no or very little content in the finally formed aluminum alloy material, which is beneficial to reducing the adverse effect on the corrosion performance while exerting the strengthening effect of Mg.

[0037] By adjusting the Zn content, the solution strengthening and precipitation strengthening effects of Zn element on the aluminum alloy material can be adjusted.

[0038] By controlling the mass ratio of Mg element and Zn element within the foregoing range, it is beneficial to exert the synergistic strengthening effect.

[0039] By controlling at least one of the Mg content and the Zn content within the foregoing range, it is more beneficial for the aluminum alloy material to obtain good mechanical properties and excellent corrosion resistance.

[0040] Based on any suitable embodiment of this application, further, in some embodiments, the inevitable impurity element includes Fe element.

[0041] Based on any suitable embodiment of this application, further, in some embodiments, the aluminum alloy material satisfies one or both of the following characteristics:

[0042] The mass percentage of Mn element in the aluminum alloy material is 0.7% - 1.1%, and can be optionally 0.8% - 1.1%;

[0043] The aluminum alloy material includes or does not include the AlSiMnFe phase, and the mass fraction of the AlSiMnFe phase in the aluminum alloy material ≤ 0.2%, optionally ≤ 0.1%; optionally, the aluminum alloy material includes the AlSiMnFe phase.

[0044] In the process of casting aluminum alloy, Fe impurities are often inevitably present in the formed aluminum alloy, and the Fe impurities can form needle-like AlSiMnFe phase.

[0045] The addition of Mn element can play a strengthening role, mainly by being dissolved in the matrix Al and increasing the strength of the matrix Al through lattice distortion. In addition, the generated AlSiMnFe phase also has a certain strengthening effect.

[0046] Due to the large contact area and significant potential difference between the AlSiMnFe phase and the α-Al matrix, local galvanic corrosion may occur.

[0047] A small amount of Fe (such as Fe content ≤ 0.7 wt%) helps with demolding during the casting process. However, when the Fe content is relatively high, it is likely to reduce the corrosion resistance of the aluminum alloy material. By controlling the Fe content within a lower range, it is beneficial to reduce the adverse effect of Fe on the corrosion resistance.

[0048] In addition, the introduction of Cu element can also transform a part of the needle-like AlSiMnFe phase into multi-branched AlSiMnFeCu, which is also conducive to reducing the damage of the needle-like AlSiMnFe phase to the corrosion resistance.

[0049] By adjusting the content of Mn element, the content of the needle-like AlSiMnFe phase can be regulated. By regulating the content of the AlSiMnFe phase, the comprehensive performance of the corrosion resistance and mechanical properties of the aluminum alloy material can be improved.

[0050] Based on any suitable embodiment of the present application, further, in some embodiments, the mass percentage of Sr element in the aluminum alloy material is 200 ppm to 500 ppm.

[0051] By adjusting the content of Sr element, the modification effect of Sr element on the alloy phase can be adjusted. By controlling the Sr content within a more suitable range, it is more conducive to the optimization of the mechanical properties of the aluminum alloy material.

[0052] Based on any suitable embodiment of the present application, further, in some embodiments, by mass percentage, the aluminum alloy material comprises the following constituent elements: 6% - 11% of Si, 0.5% - 0.9% of Cu, 0.1% - 0.4% of Ti, 0.3% - 0.6% of Mg, 0.3% - 0.6% of Zn, 0.5% - 1.1% of Mn, 0.01% - 0.05% of Sr, the inevitable impurity elements and the balance matrix element Al.

[0053] Based on any suitable embodiment of the present application, further, in some embodiments, by mass percentage, the aluminum alloy material comprises the following constituent elements: 6.5% - 11% of Si, 0.5% - 0.8% of Cu, 0.2% - 0.4% of Ti, 0.3% - 0.6% of Mg, 0.3% - 0.6% of Zn, 0.7% - 1.1% of Mn, 0.02% - 0.05% of Sr, the inevitable impurity elements and the balance matrix element Al.

[0054] Based on any suitable embodiment of the present application, further, in some embodiments, by mass percentage, the aluminum alloy material comprises the following constituent elements: 8% - 11% of Si, 0.6% - 0.8% of Cu, 0.25% - 0.4% of Ti, 0.3% - 0.5% of Mg, 0.4% - 0.6% of Zn, 0.8% - 1.1% of Mn, 0.03% - 0.05% of Sr, the inevitable impurity elements, and the balance matrix element Al.

[0055] By adjusting the types and contents of the various elements in the aluminum alloy material, it is more conducive to the aluminum alloy material obtaining good mechanical properties and excellent corrosion resistance.

[0056] In the second aspect of the present application, there is provided an aluminum alloy structural member, which is a formed body of the aluminum alloy material described in the first aspect of the present application.

[0057] In the third aspect of the present application, there is provided a method for preparing an aluminum alloy structural member, which comprises the following steps:

[0058] Heat and melt the aluminum ingot, add the ingredients determined according to the nominal composition of the aluminum alloy material described in the first aspect of the present application in the form of master alloys, carry out melting and refining and slag skimming to prepare a refined aluminum alloy melt;

[0059] Pour and mold the refined aluminum alloy melt to prepare an aluminum alloy ingot;

[0060] Perform heat treatment on the aluminum alloy ingot and cool it to obtain the aluminum alloy structural member.

[0061] The aluminum alloy structural member, which is a formed body of the aluminum alloy material described in the first aspect of the present application, can have good mechanical properties and excellent corrosion resistance, and can be used as the aluminum alloy structural member in the battery box, which can effectively extend the service life of the battery box. This aluminum alloy structural member can use aluminum ingots to provide the matrix elements, supplemented by corresponding alloy elements, and is prepared into an aluminum alloy structural member through melting and refining, slag skimming, pouring and molding, heat treatment and cooling. The shape and size of the aluminum alloy structural member can be controlled by selecting a mold with a corresponding shape and size in the pouring and molding step. It can be understood that the shape and size of the cooled structural member can also be adjusted to obtain an aluminum alloy structural member with a target shape and size. For example, treatment methods including but not limited to sandblasting and grinding can be used.

[0062] In the fourth aspect of the present application, there is provided a battery box, and the battery box satisfies at least one of the following characteristics:

[0063] At least a part of the structural members in the battery box contain the aluminum alloy material described in the first aspect of the present application;

[0064] The battery box body includes the aluminum alloy structural member described in the second aspect of the present application; and

[0065] The battery box body includes an aluminum alloy structural member prepared by the preparation method of the aluminum alloy structural member described in the third aspect of the present application.

[0066] The battery box body can provide protection for the battery cells inside. On the one hand, the battery box body needs to have good mechanical strength to reduce the damage degree of the battery when it is impacted. On the other hand, during the storage and battery cycling process of the battery box body, it is prone to suffer from galvanic corrosion damage. Therefore, the battery box body also needs to have a certain corrosion resistance. The battery box body made of the aforementioned aluminum alloy material or aluminum alloy structural member can meet the requirements of the battery box body for mechanical properties and corrosion resistance at the same time.

[0067] In the fifth aspect of the present application, a battery system is provided, which includes the battery box body described in the fourth aspect of the present application and battery cells located inside the battery box body.

[0068] Based on any suitable implementation manner of the present application, further, in some implementation manners, the battery cells include a liquid electrolyte.

[0069] In the sixth aspect of the present application, an electrical device is provided, which includes at least one of the aluminum alloy material described in the first aspect of the present application, the aluminum alloy structural member described in the second aspect of the present application, the aluminum alloy structural member prepared by the preparation method of the aluminum alloy structural member described in the third aspect of the present application, the battery box body described in the fourth aspect of the present application, and the battery system described in the fifth aspect of the present application.

[0070] By using the aforementioned aluminum alloy material, using the aforementioned aluminum alloy structural member, or using a battery box body including the aforementioned aluminum alloy material or aluminum alloy structural member in one or more of the battery system and the electrical device, it is beneficial to improve the reliability and lifespan of the battery system and the electrical device. It can not only reduce the damage degree of the battery when it is impacted, but also improve the corrosion resistance of the battery box body, including but not limited to improving the resistance to galvanic corrosion.

[0071] When the battery cells in the battery system include a liquid electrolyte, the requirement for the corrosion resistance of the battery box body is higher, and the aforementioned provided battery system and electrical device are more likely to meet the storage and use requirements.

[0072] In the seventh aspect of the present application, an application of the aluminum alloy material described in the first aspect of the present application in the preparation of at least one of an aluminum alloy structural member, a battery box body, a battery system, and an electrical device is provided.

[0073] Details of one or more embodiments of the present application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the present application will become apparent from the specification, the drawings, and the claims. Description of the Drawings

[0074] To better describe and illustrate the embodiments, examples, or instances provided by the present application, reference may be made to one or more of the accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the presently described embodiments, examples, or instances, and the best mode of these applications currently understood. Moreover, in all the drawings, the same reference numerals are used to represent the same components. It should also be noted that the drawings are all drawn in simplified forms and are only used to facilitate and clearly assist in the description of the present application. The various dimensions of each component shown in the drawings are arbitrarily shown and may be accurate or may not be drawn to actual scale. For example, to make the illustration clearer, the dimensions of some components in the drawings are appropriately exaggerated. Unless otherwise specified, the components in the drawings are not drawn to scale. The present application does not limit each dimension of each component.

[0075] In the accompanying drawings:

[0076] Figure 1 is the metallographic structure diagram of the aluminum alloy material in one embodiment of the present application.

[0077] Figure 2 is the X-ray diffraction (XRD) pattern of the aluminum alloy material in one embodiment of the present application.

[0078] Figure 3 is the microstructure and element distribution of the aluminum alloy material in one embodiment of the present application.

[0079] Figure 4 is the SEM-EDS image of the aluminum alloy material in one embodiment of the present application, which is a field emission scanning electron microscope FESEM+EDS (with an energy dispersive spectrometer) point scan map, identifying three scanned points.

[0080] Figure 5 is the curve of the mass fraction, elastic modulus, thermal conductivity, and density of the aluminum alloy material varying with temperature in one embodiment of the present application. Among them, the mass fraction refers to the mass fraction of the aluminum alloy material at different temperatures relative to the initial mass of the aluminum alloy material in the unheated state, reflecting the thermal weight loss of the aluminum alloy material.

[0081] Figure 6 is the alternating current impedance test result of the aluminum alloy material in one embodiment of the present application.

[0082] Figure 7 is Figure 5The equivalent circuit diagram for fitting the alternating current impedance test of the aluminum alloy material.

[0083] Figure 8 is the potentiodynamic polarization curve of the aluminum alloy material in an embodiment of the present application. The abscissa is the chemical potential (unit: V), and the ordinate is the current density (A / cm 2 ).

[0084] Figure 9 is the macroscopic surface morphology diagram of the aluminum alloy material at different corrosion times in the salt spray corrosion test in an embodiment of the present application.

[0085] Figure 10 is the schematic diagram of the sample size of the tensile test of the aluminum alloy material in an embodiment of the present application.

[0086] Figure 11 is the schematic diagram of the battery module in an embodiment of the present application.

[0087] Figure 12 is the schematic diagram of the battery pack in an embodiment of the present application.

[0088] Figure 13 is Figure 12 the exploded view of the battery pack shown in an embodiment of the present application.

[0089] Figure 14 is the schematic diagram of the electrical device in an embodiment of the present application.

[0090] Explanation of reference numerals: 1 is the battery pack; 2 is the upper box body; 3 is the lower box body; 4 is the battery module; 5 is the battery cell; 6 is the electrical device. Detailed implementation manners

[0091] Hereinafter, some embodiments of the aluminum alloy material, aluminum alloy structural member and their preparation methods, battery box body, battery system, electrical device and application of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where non-essential detailed descriptions are omitted. For example, there are cases where the detailed descriptions of well-known matters are omitted and the repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0092] The "range" disclosed in this application can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can include or exclude the end values. Any end value can be independently included or excluded, and any combination can be made, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are also listed, the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In this application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when stating that a certain parameter is an integer selected from "2 - 10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0093] In this application, when referring to "multiple", "diverse", "a number of", "several", etc., unless otherwise specified, it means greater than 2 or equal to 2 in quantity. For example, "one or more" means one or greater than or equal to two. It can be understood that when referring to "any number of" items, it refers to any suitable combination of multiple items, that is, the "any number of" items are combined in a non - conflicting and implementable manner of this application.

[0094] If there is no special instruction, all embodiments and optional embodiments of this application can be combined with each other to form a new technical solution.

[0095] Referring to "embodiment" in this text means that the specific features, structures, or characteristics described in combination with the embodiment can be included in at least one embodiment or implementation manner of this application. The appearance of this phrase at various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments. The understanding of "implementation manner" mentioned in this text is similar.

[0096] Those skilled in the art can understand that in the methods of each embodiment or example, the written order of each step does not mean a strict execution order and impose any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. Without special instructions, all steps of this application can be carried out sequentially or randomly, and preferably sequentially. For example, if method M includes steps (a) and (b), it means that method M may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For another example, if method M further includes step (c), it means that step (c) can be added to method M in any order. For example, method M can include steps (a), (b) and (c), or can also include steps (a), (c) and (b), or can also include steps (c), (a) and (b), etc.

[0097] In this application, in the open technical features or technical solutions described by words such as "containing", "comprising", "including", etc., without other instructions, additional members outside the listed members are not excluded, and it can be regarded as providing both a closed feature or solution composed of the listed members and an open feature or solution that also includes additional members outside the listed members. For example, if A includes a1, a2 and a3, without other instructions, it may also include other members or may not include additional members, and it can be regarded as providing both the feature or solution of "A is composed of a1, a2 and a3" or "A is selected from a1, a2 and a3", and also providing the feature or solution of "A not only includes a1, a2 and a3, but also includes other members".

[0098] In this application, without other instructions, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0099] In this application, "optionally", "optional", "option" mean that it can be there or not, that is, it refers to any one of the two alternative options of "yes" or "no". If "optional" appears multiple times in a technical solution, without special instructions and without contradiction or mutual restriction relationship, each "optional" is independent. Without other instructions, descriptions such as "optionally include" and "optionally contain" in this application, taking "optionally include" as an example, mean "can include or not include".

[0100] In this application, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more related listed items, and also include any and all combinations of the related listed items. "Any and all combinations" includes combinations of any two related listed items, any more related listed items, or all related listed items. For example, "A and / or B" represents the set composed of A, B, and the combination of A and B. Among them, "including A and / or B" can mean "including A, including B, and including the combination of A and B", or it can also mean "including A, including B, or including the combination of A and B", which can be appropriately understood according to the context of the sentence.

[0101] As used herein, "its combination", "any combination thereof", "any combination mode thereof", etc. include all suitable combination modes of any two or more of the listed items.

[0102] In this article, the "suitable" involved in "suitable combination mode", "suitable mode", "any suitable mode", etc. is subject to being able to implement the technical solution of this application.

[0103] In this article, "preferred", "better", "more preferred", "it is advisable", "relatively better", "more preferred", etc. are only used to describe implementation manners or embodiments with better effects. It should be understood that they do not constitute a limitation on the protection scope of this application. If "preferred" appears multiple times in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction relationship, each "preferred" is independent of each other.

[0104] In this application, "further", "even further", "especially", "for example", "such as", "example", "exemplification", etc. are used for descriptive purposes and represent differences in content, but should not be understood as a limitation on the protection scope of this application.

[0105] In this application, in "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc., the terms "first", "second", "third", "fourth", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0106] In this application, the term "room temperature" generally refers to 4°C to 35°C and can refer to 20°C ± 5°C. In some embodiments of this application, room temperature refers to 20°C to 30°C.

[0107] In this application, for units related to data ranges, if a unit is only attached after the right endpoint, it means that the units of the left and right endpoints are the same. For example, both 3~5h and 3-5h indicate that the units of the left endpoint "3" and the right endpoint "5" are both h (hours), and they have the same meaning as 3h~5h. In addition, similar descriptions for other parameters such as temperature and size are understood in the same way.

[0108] In the embodiments or examples of this application, the weight of the relevant components mentioned not only can refer to the content of each component, but also can represent the proportional relationship of the weights between each component. Therefore, as long as the content of the relevant components in the embodiments or examples of this application is enlarged or reduced proportionally, it is within the scope described in this application. Further, the weight involved in the embodiments or examples of this application can be mass units well-known in the chemical industry such as μg, mg, g, kg, etc. Without other instructions, the mass ratio is equal to the corresponding weight ratio. For example, if the mass of substance A is m1 and the weight is W1, and the mass of substance B is m2 and the weight is W2, then the mass ratio m1 / m2 is numerically equal to the corresponding weight ratio W1 / W2.

[0109] In this application, without other instructions, wt% represents the weight percentage by weight, and is numerically equal to the corresponding mass percentage by mass. In this application, wt% can also be denoted as wt.%.

[0110] In this application, without other instructions, the unit (%) of the percentage involved in "mass percentage" and "mass fraction" can also be denoted as wt% or %(w / w).

[0111] In this application, "greater than or equal to" and "more than or equal to" can both be expressed as "≥", "less than or equal to" and "less than or equal to" can both be expressed as "≤", "greater than" can be equivalently expressed as ">", and "less than" can be equivalently expressed as "<". In this application, without other instructions, "greater than or equal to" and "≥" can be regarded as also providing two options of "greater than" and "equal to". In this application, without other instructions, "less than or equal to" and "≤" can be regarded as also providing two options of "less than" and "equal to".

[0112] In this application, for exemplary descriptions such as "in some embodiments (or examples)" and "in one embodiment (or example)", it can cover but is not limited to the following meanings: These solutions can be combined with other solutions in a suitable way to form new technical solutions.

[0113] For the battery box that plays a protective role outside the battery cell, it is not only required that the battery box has good mechanical properties to reduce the damage degree of the battery when it is impacted, but also required that the battery box has a certain corrosion resistance to extend the service life of the battery. For the current aluminum alloy materials, such as A380 aluminum alloy, etc., it is necessary to further improve their corrosion resistance.

[0114] In view of the above technical problems, on the one hand, the present application provides an aluminum alloy material, which has a matrix element Al and a relatively low content of Cu, such as 0.5wt% - 0.9wt% of Cu. This aluminum alloy material has good mechanical properties and excellent corrosion resistance, and can be used as the main material of the battery box, which is beneficial to improving the service life of the battery box.

[0115] In the present application, unless otherwise specified, "the aluminum alloy material is used as the main material of the battery box" means that the aluminum alloy material is used as the main material of at least a part of the structure in the battery box, and the mass ratio of the aluminum alloy material in this part of the structure can exceed 80%, further can exceed 90%, and even closer to 100% or be 100%. In the present application, unless otherwise specified, when "the aluminum alloy material is used as the main material of a structural member or a product", other functional components are allowed to be added to the aluminum alloy material to further improve the material properties without reducing the basic properties of the aluminum alloy material, especially without reducing the mechanical properties and corrosion resistance. In some embodiments, the aluminum alloy material is used as a component material of the battery box. At this time, the chemical composition of at least a part of the structure or structural member of the battery box is the same as that of the aluminum alloy material, and the mass ratio of the aluminum alloy material in the corresponding structure or corresponding structural member is 100%.

[0116] In the present application, unless otherwise specified, "the content of a certain element" refers to the mass percentage of this element in the aluminum alloy material provided by the present application. For example, "the content of Cu" refers to the mass percentage of the Cu element in the aluminum alloy material. Unless otherwise specified, "the content of a certain alloy phase" refers to the mass percentage of this alloy phase in the aluminum alloy material provided by the present application.

[0117] In some embodiments, an aluminum alloy material is provided, which includes silicon (Si) element, copper (Cu) element, titanium (Ti) element, magnesium (Mg) element, zinc (Zn) element, manganese (Mn) element, strontium (Sr) element, matrix element Al and inevitable impurity elements, and there is no Al 2 Cu phase or the content is less, such as Al 2 The mass fraction of the Al

[0118] In some embodiments, the present application provides an aluminum alloy material. By mass percentage, the aluminum alloy material includes the following constituent elements: 6% to 11% of Si, 0.5% to 0.9% of Cu, 0.1% to 0.4% of Ti, 0.2% to 0.6% of Mg, 0.25% to 0.6% of Zn, 0.5% to 1.1% of Mn, 0.01% to 0.05% of Sr, matrix element Al, and inevitable impurity elements;

[0119] Among them, the aluminum alloy material includes or does not include Al 2 Cu phase. Further, Al 2 The mass fraction of the Cu phase in the aluminum alloy material can satisfy ≤ 1.3%.

[0120] In the present application, unless otherwise specified, "matrix element" refers to the element that provides the matrix phase. When casting an alloy, the ingot of the matrix element is often used as the starting material, and on this basis, modification elements are added to finally form an alloy phase including multiple elements. In the present application, the matrix element of the aluminum alloy material is Al.

[0121] In the present application, unless otherwise specified, "inevitable impurities" refer to impurity elements that are not intentionally introduced but are inevitably brought in during the preparation process.

[0122] In the present application, methods including but not limited to the following can be used to characterize and analyze the element composition, alloy phase, alloy structure, etc. of the aluminum alloy material: X-ray diffraction (XRD) method, energy dispersive spectrometer (EDS), scanning electron microscope (SEM), metallographic microscope, etc. The operation methods and data analysis methods of these instruments are well-known to those skilled in the art. Unless otherwise specified, the detection and analysis methods in the following example part can be used, but are not limited thereto.

[0123] This aluminum alloy material has aluminum (Al) as the matrix element, and includes silicon (Si) element, copper (Cu) element, titanium (Ti) element, magnesium (Mg) element, zinc (Zn) element, manganese (Mn) element, and strontium (Sr) element. By controlling the constituent elements of the aluminum alloy material within the foregoing content ranges. The matrix element Al in this aluminum alloy material forms an α-Al matrix phase, and this matrix phase is mainly distributed in a near-equiaxed crystal form. The Si element can form an Al-Si eutectic phase with the α-Al matrix phase, which can provide good basic mechanical properties. The introduction of the Cu element may form a bone-shaped or needle-shaped Al 2 Cu phase, Al 2The Cu phase has a certain strengthening effect; although an increase in the Cu content is beneficial to improving the mechanical strength of the material, such as combining with impurities to change the morphology of the impurity phase and thus reducing the damage of the impurity phase to the mechanical properties; however, a high content of Cu elements easily leads to a decrease in the corrosion resistance of the aluminum alloy material and also easily reduces the elongation of the aluminum alloy material. Al 2 The potential of the Cu phase is relatively positive, and the potential of the matrix phase with a higher Cu content is also relatively positive. At this time, the matrix phase with a lower Cu content will act as the cathode phase, together with the nearby Cu-rich matrix phase and Al 2 The Cu phase forms an electrochemical microcell locally, causing the matrix phase part of the Cu-depleted solid solution to be continuously corroded. Al 2 The content of 2 is basically linearly related to the Cu content. By designing a relatively low copper content, the proportion of the 2 phase can be reduced, thereby improving the corrosion resistance and elongation of the material. In addition, in the aluminum alloy material provided above, by using only a small amount of Cu elements, the strengthening effect can be achieved while having no adverse effect or a small effect on the corrosion resistance. By introducing Ti elements, round or nearly elliptical precipitation phases can be formed. These precipitation phases can serve as non-spontaneous nucleation sites during crystallization, having a certain grain refinement effect, and can play a strengthening role and improve the elongation. The introduction of Mg elements and Zn elements can improve the strength of the aluminum alloy material by forming solid solutions and precipitation strengthening. Sr elements can dissolve in the matrix phase. Sr can change the solidification process during casting and play a modification role on the alloy phase of the aluminum alloy material, and can modify the Al-Si eutectic structure into fine fibrous shapes, thereby improving the mechanical strength. Mn elements can supplement the strengthening effect of Mg elements and make the precipitation phases evenly distributed. In addition, the introduction of Mn elements helps the demolding process during casting and can also combine with impurity elements to reduce the damage of the impurity elements to the corrosion resistance of the aluminum alloy material. By designing the element composition and element content in the aluminum alloy material, the prepared aluminum alloy material can have a special microstructure. Through multiple synergistic effects among the elements, while effectively improving the corrosion resistance of the aluminum alloy material, the aluminum alloy material also has good mechanical properties, with both the mechanical strength and the ductility performance being improved. By reasonably setting the contents of elements such as Cu elements, Mg elements, and Zn elements, a foundation can be laid for the aluminum alloy material to have good mechanical properties such as tensile strength and hardness; and by controlling the contents of Cu elements, Ti elements, and Sr elements in the aluminum alloy material, the corrosion resistance of the aluminum alloy material can be significantly improved.

[0124] ​​In some embodiments, the mass percentage of Cu element in the aluminum alloy material can be 0.5% - 0.9%, optionally 0.5% - 0.8%, and further optionally 0.6% - 0.8%. The mass percentage of Cu element in the aluminum alloy material can also be any one of the following percentages, or an interval composed of any two of the following percentages: 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, etc.

[0125] In some embodiments, the aluminum alloy material may or may not include Al 2 Cu phase. Without limitation, Al 2 The mass fraction of the Al 2 Cu phase in the aluminum alloy material can satisfy ≤ 1.3%, optionally 0.1% - 1.3%, and further optionally 0.8% - 1.3%. The mass fraction of the Al 2 Cu phase in the aluminum alloy material can also be any one of the following percentages, or an interval composed of any two of the following percentages: 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.87%, 0.9%, 1.0%, 1.1%, 1.2%, 1.29%, etc. Al 2 The mass fraction of the Al

[0126] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material satisfies one or two of the following characteristics (any numerical parameter in the following characteristics can also be selected from any suitable value or range in the context):

[0127] The mass percentage of Cu element in the aluminum alloy material is 0.5% - 0.9%, optionally 0.5% - 0.8%, and further optionally 0.6% - 0.8% (it can also be selected from any suitable content or range in the context);

[0128] The aluminum alloy material includes or does not include Al 2 Cu phase, optionally, Al 2 The mass fraction of the Al 2 Cu phase in the aluminum alloy material ≤ 1.3%; further optionally, the aluminum alloy material includes Al 2The mass fraction of the Cu phase in the aluminum alloy material is 0.1% to 1.3%, and more preferably 0.8% to 1.3% (it can also be selected from any suitable content or range in the context).

[0129] By adjusting the mass percentage of the Cu element in the aluminum alloy material, the content of the Al 2 Cu phase can be regulated. By controlling the content of the Al 2 Cu phase within the aforementioned range, it is more conducive for the aluminum alloy material to obtain good mechanical properties and excellent corrosion resistance, and it is more conducive to having good mechanical strength and ductility while obtaining excellent corrosion resistance.

[0130] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material includes a fibrous Al-Si eutectic structure.

[0131] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material includes Al 3 Ti strengthening phase.

[0132] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material includes a fibrous Al-Si eutectic structure; the aluminum alloy material includes Al 3 Ti strengthening phase.

[0133] In the aluminum alloy material, the α-Al matrix phase and the Si phase form an Al-Si eutectic phase, and this eutectic phase is mainly distributed in the form of fine fibrous structures between the α-Al grains, which is beneficial to improving the mechanical strength of the matrix phase. The Ti element can form round or nearly elliptical Al 3 Ti precipitation phases, and these precipitation phases can serve as non-spontaneous nucleation sites during crystallization, playing a certain role in grain refinement and can have a strengthening effect. In addition, the improvement of the distribution of the second-phase structure and fine-grain strengthening are both beneficial to improving the ductility.

[0134] In some embodiments, the mass percentage of the Si element in the aluminum alloy material is 6% to 11%, preferably 6.5% to 11%, and more preferably 8% to 11%. The mass percentage of the Si element in the aluminum alloy material can also be any one of the following percentages, or an interval composed of any two of the following percentages: 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, etc. The mass percentage of Si in the aluminum alloy material can also be selected from any suitable range among the following ranges: 6.5% to 10.5%, 8.5% to 10.5%, etc.

[0135] Regarding the content of Si element, the eutectic point of Al-Si alloy is 12.5 wt%, and after exceeding the eutectic point, primary silicon will be generated first, which is not conducive to corrosion resistance. In this application, the morphology of Al-Si eutectic structure can be adjusted by adjusting the content of Si element.

[0136] In some embodiments, the mass percentage of Ti element in the aluminum alloy material is 0.1% - 0.4%, optionally 0.2% - 0.4%, and further optionally 0.25% - 0.4%. The mass percentage of Ti element in the aluminum alloy material can also be any one of the following percentages, or an interval composed of any two of the following percentages: 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, etc. The mass percentage of Ti element in the aluminum alloy material can also be selected from any suitable range in the following ranges: 0.25% - 0.35%, 0.2% - 0.3%, 0.1% - 0.3%, 0.3% - 0.4%, etc.

[0137] In some embodiments, Al 3 The mass fraction of Al-Ti strengthening phase in the aluminum alloy material is optionally 0.3% - 2%, optionally 0.3% - 1%, and further optionally 0.35% - 0.6%. Al 3 The mass fraction of Al-Ti strengthening phase in the aluminum alloy material can also be any one of the following percentages, or an interval composed of any two of the following percentages: 0.3%, 0.35%, 0.4%, 0.45%, 0.46%, 0.48%, 0.49%, 0.5%, 0.51%, 0.52%, 0.54%, 0.55%, 0.56%, 0.58%, 0.6%, 0.62%, 0.64%, 0.65%, 0.66%, 0.68%, 0.7%, 0.8%, 0.9%, 1.0%, 1.2%, 1.5%, 1.6%, 1.8%, 2.0%, etc. Al 3 The mass fraction of Al-Ti strengthening phase in the aluminum alloy material can also be selected from any suitable range in the following ranges: 0.5% - 2%, about 0.5%, etc. Here, "about" means a reasonable fluctuation range. For example, about 0.5% can be ±0.05%, ±0.06%, ±0.08%, ±0.01%, ±0.15%, etc. The Al content can be adjusted to generate Al-Ti strengthening phase, and at the same time, the Al-Ti strengthening phase is controlled within a relatively small range. For example, the mass fraction of Al-Ti strengthening phase in the aluminum alloy material can be controlled to be about 0.5%. The reduction of the precipitation phase is beneficial to improving the ductility. 3 Ti strengthening phase, and at the same time, the Al-Ti strengthening phase is also controlled within a relatively small range. For example, the Al-Ti strengthening phase can be controlled. 3 Ti strengthening phase within a relatively small range. For example, the Al-Ti strengthening phase can be controlled. 3 Ti strengthening phase in the aluminum alloy material is about 0.5%. The reduction of the precipitation phase is beneficial to improving the ductility.

[0138] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material satisfies one, two, or three of the following characteristics (any numerical parameter in the following characteristics can also be selected from any suitable value or range in the context):

[0139] The mass percentage of Si element in the aluminum alloy material is 6% - 11%, optionally 6.5% - 11%, and further optionally 8% - 11% (it can also be selected from any suitable content or range in the context);

[0140] The mass percentage of Ti element in the aluminum alloy material is 0.1% - 0.4%, optionally 0.2% - 0.4%, and further optionally 0.25% - 0.4% (it can also be selected from any suitable content or range in the context);

[0141] Al 3 The mass fraction of Al 0.3％～2％， Ti strengthening phase in the aluminum alloy material is optionally 0.3% - 1%, and further optionally 0.35% - 0.6% (it can also be selected from any suitable content or range in the context).

[0142] By adjusting the content of Ti element, the content of Al 3 Ti strengthening phase can be regulated. By adjusting one or more of these content parameters, the mechanical properties of the aluminum alloy material can be adjusted. Within the foregoing range, it is beneficial to provide good mechanical strength while reducing the Cu content.

[0143] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material may or may not include Mg 2 Si phase. Without limitation, the mass fraction of Mg 2 Si phase in the aluminum alloy material can satisfy ≤0.05%, and is optionally 0% (that is, it does not exist). The mass fraction of Mg 2 Si phase in the aluminum alloy material can also be any of the following percentages, or less than or equal to any of the following percentages, or selected from the intervals formed by any two of the following percentages, or selected from the intervals formed by any of the following percentages and 0%: 0.005%, 0.006%, 0.008%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, etc.

[0144] The introduction of Mg element may also produce Al 5 Cu 2 Mg 8 Si 16 phase, which can play a role in high-temperature strengthening. Mg 2 Si phase can also strengthen the aluminum alloy, but Mg 2The Si phase is a strong cathodic phase, which is likely to accelerate the corrosion of the matrix and cause damage to the corrosion resistance of aluminum alloy materials. In the aluminum alloy material system provided in this application, Mg usually begins to precipitate when the Mg content exceeds about 1.2 wt%. 2 Si phase. By regulating the Mg content, the precipitation behavior of the Mg 2 Si phase can be regulated, so that the Mg 2 Si phase that appears in the intermediate process is dissolved, so that there is little or no content in the finally formed aluminum alloy material, which is beneficial to reducing the adverse effect on the corrosion resistance while exerting the strengthening effect of the Mg element.

[0145] In some embodiments, the mass percentage of the Mg element in the aluminum alloy material is 0.2% - 0.6%, optionally 0.3% - 0.6%, and further optionally 0.3% - 0.5%. The mass percentage of the Mg element in the aluminum alloy material can also be any one of the following percentages, or an interval composed of any two of the following percentages: 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, etc. The mass percentage of the Mg element in the aluminum alloy material can also be selected from any suitable range in the following ranges: 0.35% - 0.5%, 0.3% - 0.45%, 0.35% - 0.45%, 0.4% - 0.5%, 0.4% - 0.6%, 0.3% - 0.4%, etc.

[0146] In some embodiments, the mass percentage of the Zn element in the aluminum alloy material is 0.25% - 0.6%, optionally 0.3% - 0.6%, and further optionally 0.4% - 0.6%. The mass percentage of the Zn element in the aluminum alloy material can also be any one of the following percentages, or an interval composed of any two of the following percentages: 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, etc. The mass percentage of the Zn element in the aluminum alloy material can also be selected from any suitable range in the following ranges: 0.45% - 0.6%, 0.4% - 0.55%, 0.3% - 0.5%, 0.4% - 0.5%, etc.

[0147] In some embodiments, the mass ratio of the Mg element to the Zn element in the aluminum alloy material is 1:(1.1 - 1.3), optionally 1:(1.1 - 1.25). The mass ratio of the Mg element to the Zn element in the aluminum alloy material can also be any one of the following ratios, and can also be selected from an interval composed of any two of the following ratios: 1:1.1, 1:1.15, 1:1.2, 1:1.25, 1:1.3, etc. The mass ratio of the Mg element to the Zn element in the aluminum alloy material can also be selected from any suitable range in the following ranges: 1:(1.1 - 1.2), etc.

[0148] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material satisfies one or two or three of the following characteristics (any numerical parameter in the following characteristics can also be selected from any suitable value or range in the context):

[0149] The mass percentage of Mg element in the aluminum alloy material is 0.2% - 0.6%, optionally 0.3% - 0.6%, and further optionally 0.3% - 0.5% (it can also be selected from any suitable content or range in the context);

[0150] The mass percentage of Zn element in the aluminum alloy material is 0.25% - 0.6%, optionally 0.3% - 0.6%, and further optionally 0.4% - 0.6% (it can also be selected from any suitable content or range in the context);

[0151] The mass ratio of Mg element to Zn element in the aluminum alloy material is 1:(1.1 - 1.3), optionally 1:(1.1 - 1.25) (it can also be selected from any suitable content or range in the context).

[0152] By adjusting the Zn content, the solution strengthening and precipitation strengthening effects of Zn element on the aluminum alloy material can be adjusted.

[0153] By controlling the mass ratio of Mg element to Zn element within the foregoing range, it is beneficial to exert the synergistic strengthening effect.

[0154] By controlling at least one of the Mg content and the Zn content within the foregoing range, it is more beneficial for the aluminum alloy material to obtain good mechanical properties and excellent corrosion resistance.

[0155] Based on any suitable embodiment of the present application, further, in some embodiments, the inevitable impurity element includes Fe element.

[0156] In some embodiments, the mass percentage of Mn element in the aluminum alloy material is 0.5% - 1.1%, optionally 0.7% - 1.1%, and further optionally 0.8% - 1.1%. The mass percentage of Mn element in the aluminum alloy material can also be any one of the following percentages, or an interval composed of any two of the following percentages: 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, etc. The mass percentage of Mn element in the aluminum alloy material can also be selected from any suitable range in the following ranges: 0.6% - 1.0%, 0.8% - 1.0%, etc.

[0157] In some embodiments, the mass fraction of AlSiMnFe phase in the aluminum alloy material (can be denoted as f AlSiMnFe) ≤ 0.2%, optionally ≤ 0.1%. In some embodiments, the aluminum alloy material includes an AlSiMnFe phase. The mass fraction of the AlSiMnFe phase in the aluminum alloy material can be any of the following percentages, can also be an interval composed of any two of the following percentages, can also be less than or equal to any of the following percentages, can also be greater than 0% and less than or equal to any of the following percentages, can also be greater than or equal to 0% and less than or equal to any of the following percentages: 0.01%, 0.02%, 0.04%, 0.05%, 0.06%, 0.08%, 0.09%, 0.1%, 0.12%, 0.15%, 0.16%, 0.18%, 0.2%, etc. For example, the mass fraction of the AlSiMnFe phase in the aluminum alloy material can be selected from any suitable range in the following range: 0 < f AlSiMnFe ≤ 0.2%, 0 < f AlSiMnFe ≤ 0.1%, etc.

[0158] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material satisfies one or two of the following characteristics (any numerical parameter in the following characteristics can also be selected from any suitable value or range in the context):

[0159] The mass percentage of Mn element in the aluminum alloy material is 0.5% - 1.1%, optionally 0.7% - 1.1%, and further optionally 0.8% - 1.1% (can also be selected from any suitable content or range in the context);

[0160] The aluminum alloy material includes or does not include an AlSiMnFe phase, and the mass fraction of the AlSiMnFe phase in the aluminum alloy material ≤ 0.2%, optionally ≤ 0.1% (can also be selected from any suitable content or range in the context).

[0161] In the process of casting aluminum alloy, it is often inevitable that Fe impurities exist in the formed aluminum alloy, and the Fe impurities can form needle-like AlSiMnFe phases.

[0162] The addition of Mn element can play a strengthening role, mainly relying on being dissolved in the matrix Al and increasing the strength of the matrix Al through lattice distortion. In addition, the generated AlSiMnFe phase also has a certain strengthening effect.

[0163] Due to the large contact area and large potential difference between the AlSiMnFe phase and the α - Al matrix, local galvanic corrosion may occur.

[0164] A small amount of Fe element (such as Fe content ≤ 0.7wt%) helps with demolding during the casting process. However, when the Fe content is relatively high, it is easy to reduce the corrosion resistance of the aluminum alloy material. By controlling the Fe content within a lower content range, it is beneficial to reduce the adverse effect of Fe on the corrosion resistance.

[0165] In addition, the introduction of Cu element can also transform a part of acicular AlSiMnFe phase into multi-branched AlSiMnFeCu, which is also beneficial to reducing the damage of acicular AlSiMnFe phase to the corrosion resistance.

[0166] By adjusting the content of Mn element, the content of acicular AlSiMnFe phase can be regulated. By regulating the content of AlSiMnFe phase, the comprehensive properties of corrosion resistance and mechanical properties of aluminum alloy materials can be improved.

[0167] Based on any suitable embodiment of the present application, further, in some embodiments, the mass ratio of Sr element in the aluminum alloy material is 0.01% - 0.05%, and can be selected as 200 ppm - 500 ppm. Among them, 1 ppm represents one millionth. 1 ppm = 0.0001%, 200 ppm = 0.02%. The mass ratio of Sr in the aluminum alloy material can also be any one of the following values, or selected from the intervals formed by any two of the following values: 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm, 500 ppm, etc. The mass ratio of Sr element in the aluminum alloy material can also be selected from any suitable range in the following ranges: 300 ppm - 500 ppm, etc.

[0168] By adjusting the content of Sr element, the modification effect of Sr element on alloy phases can be adjusted. By controlling the Sr content within a more suitable range, it is more beneficial to optimize the mechanical properties of aluminum alloy materials.

[0169] Based on any suitable embodiment of the present application, further, in some embodiments, by mass percentage, the aluminum alloy material includes the following constituent elements: 6% - 11% of Si, 0.5% - 0.9% of Cu, 0.1% - 0.4% of Ti, 0.3% - 0.6% of Mg, 0.3% - 0.6% of Zn, 0.5% - 1.1% of Mn, 0.01% - 0.05% of Sr, inevitable impurity elements and the balance of matrix element Al.

[0170] Based on any suitable embodiment of the present application, further, in some embodiments, by mass percentage, the aluminum alloy material includes the following constituent elements: 6.5% - 11% of Si, 0.5% - 0.8% of Cu, 0.2% - 0.4% of Ti, 0.3% - 0.6% of Mg, 0.3% - 0.6% of Zn, 0.7% - 1.1% of Mn, 0.02% - 0.05% of Sr, inevitable impurity elements and the balance of matrix element Al.

[0171] Based on any suitable embodiment of the present application, further, in some embodiments, by mass percentage, the aluminum alloy material comprises the following constituent elements: 8% - 11% Si, 0.6% - 0.8% Cu, 0.25% - 0.4% Ti, 0.3% - 0.5% Mg, 0.4% - 0.6% Zn, 0.8% - 1.1% Mn, 0.03% - 0.05% Sr, inevitable impurity elements, and the balance matrix element Al.

[0172] By adjusting the types and contents of the various elements in the aluminum alloy material, it is more conducive for the aluminum alloy material to obtain good mechanical properties and excellent corrosion resistance.

[0173] In some embodiments, by reasonably designing the element composition and element content, the aluminum alloy material has a Figure 1 microstructure as shown: near-equiaxed α-Al crystals and fine, fibrous eutectic structures, as well as a small amount of Al 3 Ti, AlSiMnFe and other alloy phases.

[0174] In another aspect of the present application, a preparation method of an aluminum alloy material is provided, which can be used to prepare the aluminum alloy material described in the first aspect of the present application.

[0175] In some embodiments, a preparation method of an aluminum alloy material is provided, which comprises the following steps:

[0176] S100 (smelting): Heating and melting aluminum ingots, adding the ingredients determined according to the nominal composition of the aluminum alloy material in the form of master alloys, carrying out melting and refining and slag skimming to prepare a refined melt;

[0177] S200 (forming): Pouring and forming the refined melt to prepare an ingot;

[0178] S300 (heat treatment): Carrying out heat treatment on the ingot and cooling to obtain the aluminum alloy material.

[0179] In the present application, unless otherwise specified, "nominal composition" refers to the theoretical value or design value of the target composition.

[0180] In step S100, a refined melt is prepared by smelting. The obtained refined melt is also denoted as the aluminum alloy refined melt.

[0181] In the present application, "smelting" has a well-known meaning in the art, and refers to the operation of heating and melting solid metal and performing tempering, which is one of the processes for casting alloys. Generally, a smelting furnace is required in the smelting process, in which other components required for preparing the alloy are melted, and the material is smelted into the required alloy through operations such as slagging and refining. Other components required for preparing the alloy may include metal ingots that provide matrix elements and necessary alloy components. In the present application, before casting and molding, it is necessary to first perform smelting to obtain a refined melt containing the required components of the aluminum alloy material. When the nominal composition of the aluminum alloy material is determined, those skilled in the art can reasonably determine the implementation method of smelting.

[0182] Each alloying element can be added in the form of a master alloy, but is not limited thereto. When the nominal composition of the aluminum alloy material is determined, those skilled in the art can select a suitable addition temperature and timing according to the characteristics (such as melting point) of each alloying element, so that the material is in a molten state throughout the entire process from heating and melting the aluminum ingot to obtaining the refined melt.

[0183] The addition of some elements may require consideration of the burn-out rate. For example, in some embodiments, taking 1 kilogram (kg) as an example, the burn-out rate of Zn is 12%, and the burn-out rate of Mg is 15%, expressed in mass percentage.

[0184] In some embodiments, Mg and Zn are added in the form of pure metals. Since pure metal Mg and Zn are easily burned, they can be added after Si, Mn, and Cu with high melting points are completely melted and appropriately cooled.

[0185] In some embodiments, the elements are added in the following manner: AlSi 20 、AlCu 50 、AlTi 5 、Zn、Mg、AlMn 10 、AlSr 10 The numbers represent the atomic ratios of the elements, and different numbers correspond to different alloy grades. Those skilled in the art know the meaning of the corresponding grades.

[0186] In the present application, unless otherwise specified, "melting refining" refers to refining the material in a molten state so that the elements in the material diffuse with each other and mix fully to form a uniform liquid melt.

[0187] Without limitation, melt refining includes refining.

[0188] In the present application, "refining" has its well-known meaning in the art and refers to the step of obtaining a high-purity alloy by removing impurities and impure substances. A suitable refining method can be selected according to the compositional characteristics of the aluminum alloy material. Without limitation, the refining purpose can be achieved by adding a refining agent. The refining agent used in the present application can be a common refining agent for casting aluminum alloys, such as an efficient refining agent (non-toxic refining agent), a degassing refining agent, etc.

[0189] In the present application, "skimming" has its well-known meaning in the art and refers to the step of removing dross from the melt during the smelting process. During the melting and refining process, dross that may float on the surface of the melt can be removed by skimming. The number of skimming operations can be one or more.

[0190] In step S200, an ingot is prepared by casting the refined melt obtained from smelting. The obtained ingot is also referred to as an aluminum alloy ingot.

[0191] After casting and forming, the obtained ingot acquires a certain shape and size. The ingot can have a preset shape and size. Among them, the preset shape and preset size can be determined according to test samples or actual requirements. The shape and size of the ingot can be controlled by the shape and size of the mold used during casting.

[0192] In step S300, the target aluminum alloy material is prepared by heat-treating the ingot obtained by casting and forming.

[0193] Heat treatment can be achieved by holding the ingot at a certain temperature, and heat treatment can be ended by cooling.

[0194] In the step of heat-treating the ingot, heat treatment can be carried out in an insulation manner, and appropriate insulation temperature (also denoted as annealing temperature) and insulation time can be selected according to the size of the ingot to achieve a good annealing effect. Generally, the annealing insulation temperature can be slightly lower than the melting point temperature. As a non-limiting example, it can be 70% - 80% of the melting point temperature. The larger the ingot, the longer the heat treatment insulation time required. A longer insulation time helps to improve the annealing effect. The insulation time can be controlled within a certain time range to avoid overburning and coarse grains while achieving a good annealing effect. Skimming slag frequently during the insulation process helps to obtain an ingot with good forming. The appropriate insulation time can be selected according to the size of the ingot. Generally, the insulation time during heat treatment is at least 0.5 h, and it can be any one of the following time lengths or also selected from the intervals composed of any two of the following time lengths: 1 h, 2 h, 3 h, 5 h, 6 h, 8 h, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 45 h, 48 h, 50 h, etc. For example, the insulation time during heat treatment can be 36 h - 50 h, further it can be 36 h - 48 h, and even further it can be 36 h - 45 h. Taking an ingot with dimensions of 20 mm × 35 mm × 10 mm as an example, the annealing time can be 1.5 h - 3 h, such as 1.5 h, 2 h, 2.5 h, 3 h, etc.

[0195] Those skilled in the art can select appropriate process parameters to effectively reduce or eliminate the intragranular segregation of elements in the aluminum alloy, so as to achieve the purpose of homogenization and realize the purpose of improving the comprehensive properties of the mechanical properties and corrosion resistance of the aluminum alloy material.

[0196] In some embodiments, in the step of heat-treating and cooling the ingot, it includes insulating and cooling the ingot.

[0197] In some embodiments, in the step of insulating and cooling the ingot, the insulation temperature can be 500 °C - 600 °C. The insulation time can be determined with reference to the foregoing method. In some of these embodiments, the insulation time can be 1 h - 3 h, further it can be 1.5 h - 2.5 h, 1.5 h - 2 h, etc., such as 1 h, 1.5 h, 2 h, 2.5 h, etc. In some other embodiments, the insulation time can be 36 h - 50 h, further it can be 36 h - 48 h, and even further it can be 36 h - 45 h, such as 36 h, 40 h, 45 h, 48 h, etc.

[0198] In some embodiments, in the step of heat-treating and cooling the ingot, it is cooled to 20 °C - 30 °C.

[0199] Non-limitingly, the cooling medium can be an inert gas, can also be oil, and can also be air cooling, furnace cooling and other methods.

[0200] In some embodiments, a method for preparing an aluminum alloy material is provided.

[0201] In some embodiments, a method for preparing an aluminum alloy material is provided, which comprises the following steps:

[0202] S100: Heat and melt the aluminum ingot, add the required amounts of Mn element, Si element, Cu element, Mg element, Zn element, Ti element and Sr element according to the nominal composition of the aluminum alloy material, carry out melting and refining and slag skimming to prepare a refined melt; wherein, the addition method of each element can be either pure metal or master alloy.

[0203] S200: Pour the refined melt into a mold to prepare an ingot.

[0204] S300: Keep the ingot warm and then cool it to obtain the aluminum alloy material.

[0205] In some of these embodiments, the Mn element, Si element, Cu element, Ti element and Sr element are added as master alloys, and the Mg element and Zn element are added as pure metals.

[0206] In some embodiments, step S100 includes step S110 and step S120.

[0207] In some embodiments, step S110 includes: heating and melting the aluminum ingot, adding a charge containing Mn element, Si element, Cu element, Mg element and Zn element to the melt of the aluminum ingot for melting to obtain a fourth melt.

[0208] In some embodiments, step S120 includes: carrying out slag skimming on the fourth melt, adding a refining agent, adding a charge containing Ti element and Sr element for refining to obtain a refined melt.

[0209] It should be noted that the slag skimming in step S120 can be carried out simultaneously with the implementation of step S110.

[0210] Adding the Mn element helps with demolding and can be added earlier. The Si content is relatively high and can be added relatively earlier. The addition order of the Mn element and the Si element can be not particularly limited. The Cu element can be added after adding the Mn element and the Si element, or the Mn element, Cu element and Si element can be added in sequence. The Mg element and the Zn element can be added in the form of pure metals. When added in the form of pure metals, since the Mg element and the Zn element are easily burned out, the Mg element and the Zn element can be added under the condition of appropriate temperature reduction after the Si element, Mn element and Cu element with higher melting points have been added. The Ti element and the Sr element can be added at the end, and the Sr element can be added after adding the Ti element. By adding a master alloy including the Ti element (such as AlTi5 ) can form Al 3 Ti phase, and the Al 3 Ti alloy phase can inhibit grain growth and play a role in refining grains. Sr element can be added finally, which is more conducive to exerting the modification effect of Sr element on the alloy phase.

[0211] In some embodiments, the ingredients including the following elements are sequentially added to the melt of aluminum ingot in the following manner: Mn element and Si element, then Cu element, then Mg element and Zn element, then Ti element, and then Sr element.

[0212] In some embodiments, the ingredients including the following elements are sequentially added to the melt of aluminum ingot in the following manner: Mn element, then Cu element, then Si element, a part of Ti element, Zn element and a part of Sr element, then Mg element, and then the remaining Ti element and the remaining Sr element. Further, the remaining Ti element is added first, and then the remaining Sr element is added.

[0213] In the present application, the ingredient containing X element can be denoted as "X ingredient". As one example, the ingredient containing Mn element can be denoted as Mn ingredient.

[0214] In some embodiments, in the step of heating and melting the aluminum ingot, the heating temperature can be 730°C to 750°C. Non-limiting examples of the heating temperature are 730°C, 740°C, 750°C, etc.

[0215] In some embodiments, a method for preparing an aluminum alloy material is provided, which includes the following steps:

[0216] S112: Heat the aluminum ingot to 730°C to 750°C for heat preservation, add the ingredient containing Mn element for smelting under the heat preservation condition to obtain the first melt, and add the ingredient containing Cu element to the first melt for smelting to obtain the second melt;

[0217] S114: Cool the second melt to 700°C to 720°C for heat preservation, add the ingredient containing Si element, a part of the ingredient containing Ti element, the ingredient containing Zn element and a part of the ingredient containing Sr element to the second melt for smelting under the heat preservation condition to obtain the third melt, and add the ingredient containing Mg element to the third melt for smelting at 718°C to 722°C to obtain the fourth melt;

[0218] S116: Skim the slag from the fourth melt, add a refining agent, add the ingredient containing the remaining Ti element (which can also be denoted as the remaining Ti ingredient) and the ingredient containing the remaining Sr element (which can also be denoted as the remaining Sr ingredient) for refining to obtain the refined melt;

[0219] S200: Pour the refined melt into a mold to form an ingot.

[0220] S300: Keep the ingot at a certain temperature (such as 500°C - 600°C) for an appropriate time (select an appropriate holding time according to the ingot size, such as holding for 45h - 50h, or also holding for 1h - 2h, 1.5h - 2.5h, etc.), and then cool it (such as cooling to 20°C - 30°C) to obtain an aluminum alloy material.

[0221] In some embodiments, a method for preparing an aluminum alloy material is provided, which includes the following steps:

[0222] S112: Heat the aluminum ingot to 730°C - 750°C and hold it. Add an intermediate alloy containing Mn element for melting under the holding condition to obtain a first melt. Then add an intermediate alloy containing Cu element to the first melt for melting to obtain a second melt.

[0223] S114: Cool the second melt to 700°C - 720°C and hold it. Add an intermediate alloy containing Si element, an intermediate alloy containing a part of Ti element, and a part of an intermediate alloy containing Sr element to the second melt for melting under the holding condition. Then add pure Zn metal for melting to obtain a third melt. Add pure Mg metal to the third melt at 718°C - 722°C for melting to obtain a fourth melt.

[0224] S130: Skim the slag from the fourth melt, add a refining agent, and add an intermediate alloy containing the remaining Ti element and an intermediate alloy containing the remaining Sr element for refining to obtain a refined melt.

[0225] S200: Pour the refined melt into a mold to form an ingot.

[0226] S300: Keep the ingot at a certain temperature (such as 500°C - 600°C) for an appropriate time (select an appropriate holding time according to the ingot size, such as holding for 45h - 50h, or also holding for 1h - 2h, 1.5h - 2.5h, etc.), and then cool it (such as cooling to 20°C - 30°C) to obtain an aluminum alloy material.

[0227] In some embodiments, step S100 includes the above-mentioned steps S112, S114, and S116.

[0228] In the second aspect of the present application, an aluminum alloy structural member is provided, which is a formed body of the aluminum alloy material described in the first aspect of the present application.

[0229] In this application, unless otherwise specified, the "formed body of aluminum alloy material" refers to a solid object composed of the aluminum alloy material and having a certain shape and size. The shape and size can be defined by a mold during the preparation of the aluminum alloy material, so that the prepared aluminum alloy material becomes a solid object with a certain shape and size.

[0230] The aluminum alloy structural member, which is the formed body of the aluminum alloy material described in the first aspect of this application, can have good mechanical properties and excellent corrosion resistance, and can be used as the aluminum alloy structural member in the battery box, which can effectively extend the service life of the battery box.

[0231] In the third aspect of this application, a method for preparing an aluminum alloy structural member is provided, and the method for preparing the foregoing aluminum alloy material can be adopted for preparation.

[0232] In some embodiments, a method for preparing an aluminum alloy structural member is provided, which includes the following steps:

[0233] S100 (smelting): Heat and melt the aluminum ingot, add the ingredients determined according to the nominal composition of the aluminum alloy material in the form of master alloy, carry out melting and refining and slag skimming to prepare the refined aluminum alloy melt;

[0234] S200 (forming): Cast and form the refined aluminum alloy melt to prepare an aluminum alloy ingot;

[0235] S300 (heat treatment): Carry out heat treatment on the aluminum alloy ingot and cool it to obtain the aluminum alloy structural member.

[0236] In step S100, the aluminum alloy material can be the aluminum alloy material described in the first aspect of this application.

[0237] The aluminum alloy ingot prepared in step S200 has a certain shape and size. After heat treatment and cooling in step S300, the obtained aluminum alloy material also has a certain shape and size. Therefore, the aluminum alloy structural member can be obtained while obtaining the aluminum alloy material.

[0238] The implementation manners of step S100, step S200, and step S300 can also refer to the foregoing method for preparing the aluminum alloy material, and can also refer to the embodiments or examples in the following text.

[0239] The aluminum alloy structural member can use aluminum ingots to provide matrix elements, supplemented by corresponding alloy elements, and is obtained by smelting, slag skimming, casting, heat treatment and cooling. The shape and size of the aluminum alloy structural member can be controlled by selecting a mold with corresponding shape and size in the casting step. It can be understood that the shape and size of the cooled structural member can also be adjusted to obtain an aluminum alloy structural member with the target shape and size. For example, treatment methods including but not limited to sandblasting and grinding can be used.

[0240] In the fourth aspect of the present application, a battery box is provided, and the battery box can meet at least one of the following characteristics:

[0241] At least a part of the structural members in the battery box contain the aluminum alloy material described in the first aspect of the present application;

[0242] The battery box includes the aluminum alloy structural member described in the second aspect of the present application; and

[0243] The battery box includes an aluminum alloy structural member prepared by the preparation method of the aluminum alloy structural member described in the third aspect of the present application.

[0244] The battery box can provide protection for the battery cells inside. On the one hand, the battery box needs to have good mechanical strength to reduce the damage degree of the battery when it is impacted. On the other hand, during storage and battery cycling, the battery box is prone to damage by galvanic corrosion. Therefore, the battery box also needs to have a certain corrosion resistance. The battery box made of the aforementioned aluminum alloy material or aluminum alloy structural member can meet the requirements of the battery box for mechanical properties and corrosion resistance at the same time.

[0245] Non-limitingly, the parts in the battery box containing the aforementioned aluminum alloy material can include one or more of the bottom plate, the panel and the bracket, but are not limited to these parts. The parts in the battery box containing the aforementioned aluminum alloy material can be integrally formed or fixedly connected in a suitable manner, such as seamless welding, to better match the required shape and size.

[0246] Based on any suitable implementation manner of the present application, further, in some implementation manners, the battery box includes a lithium battery box.

[0247] The aforementioned aluminum alloy material is applicable to the lithium battery box, but is not limited thereto.

[0248] In the fifth aspect of the present application, a battery system is provided, which includes the battery box described in the fourth aspect of the present application and battery cells located inside the described battery box.

[0249] Based on any suitable embodiment of the present application, further, in some embodiments, the battery cell includes a liquid electrolyte.

[0250] In a sixth aspect of the present application, there is provided an electrical device including at least one of the aluminum alloy material described in the first aspect of the present application, the aluminum alloy structural member described in the second aspect of the present application, the aluminum alloy structural member obtained by the preparation method of the aluminum alloy structural member described in the third aspect of the present application, the battery box described in the fourth aspect of the present application, and the battery system described in the fifth aspect of the present application.

[0251] In a seventh aspect of the present application, there is provided an application of the aluminum alloy material described in the first aspect of the present application in the preparation of at least one of an aluminum alloy structural member, a battery box, a battery system, and an electrical device.

[0252] By using the aforementioned aluminum alloy material in one or more of the battery system and the electrical device, using the aforementioned aluminum alloy structural member, or using a battery box including the aforementioned aluminum alloy material or aluminum alloy structural member, it is beneficial to improve the reliability and lifespan of the battery system and the electrical device. It can not only reduce the damage degree of the battery when being impacted, but also improve the corrosion resistance of the battery box, including but not limited to improving the resistance to galvanic corrosion.

[0253] In the present application, unless otherwise specified, a "battery cell" refers to a basic unit capable of converting chemical energy and electrical energy into each other.

[0254] In some embodiments, the battery cell belongs to a fuel cell, the corresponding battery box is a fuel cell box, and the corresponding battery system is a fuel cell system.

[0255] In the present application, unless otherwise specified, a "fuel cell box" refers to a battery box with fuel cell cells built therein. In the present application, unless otherwise specified, a "fuel cell" has the well-known meaning in the art and refers to a chemical device that directly converts the chemical energy of fuel into electrical energy; a "fuel cell cell" refers to a battery cell that directly converts the chemical energy of fuel into electrical energy.

[0256] In some embodiments, the battery cell belongs to a lithium battery, the corresponding battery box is a lithium battery box, and the corresponding battery system is a lithium battery system. At this time, the active ions in the battery cell include lithium ions. The lithium battery can be a lithium-ion secondary battery.

[0257] In the present application, unless otherwise specified, a "lithium battery box" refers to a battery box with lithium battery cells built therein. In the present application, unless otherwise specified, a "lithium battery" has the well-known meaning in the art and refers to a type of battery in which the active ions include lithium ions; a "lithium battery cell" refers to a battery cell in which the active ions include lithium ions.

[0258] In some embodiments, the battery cell belongs to a secondary battery, the corresponding battery box is a secondary battery box, and the corresponding battery system is a secondary battery system. In some of these embodiments, the battery cell may include a positive electrode plate, a negative electrode plate, and an electrolyte. During the charging and discharging process of the battery, active ions are embedded and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in conducting active ions between the positive electrode plate and the negative electrode plate. In some embodiments, the positive electrode plate, the negative electrode plate, and the separator can be made into an electrode assembly through a winding process or a stacking process.

[0259] When the battery cells in the battery system include a liquid electrolyte, the corrosion resistance requirement for the battery box is higher, and the battery system and the electrical device provided above can more easily meet the storage and use requirements.

[0260] The battery box includes at least one battery cell. The battery box may include one or more battery cells. The present application does not have any particular limitation on the shape of the battery cell, which can be cylindrical, square, or any other shape. In some embodiments, the battery cell may include an outer package.

[0261] The outer package of the battery cell can be used to encapsulate the above-mentioned electrode assembly and electrolyte, but is not limited thereto.

[0262] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic. Further, non-limiting examples of the plastic can include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate, etc.

[0263] In some embodiments, the outer package may include a housing and a cover plate. Among them, the housing may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving cavity. The housing has an opening communicating with the receiving cavity, and the cover plate can be covered on the opening to close the receiving cavity.

[0264] Non-limitingly, the aforementioned electrode assembly can be encapsulated in the receiving cavity; in some of these embodiments, the liquid electrolyte can infiltrate the electrode assembly; the number of electrode assemblies included in the battery cell can be one or more, and those skilled in the art can select according to actual needs.

[0265] The battery system can be a battery module 4 or a battery pack 1.

[0266] The battery module 4 includes at least one battery cell 5. The number of battery cells 5 included in the battery module 4 can be one or more, and those skilled in the art can select the appropriate number of battery cells according to the application and capacity of the battery module.

[0267] Figure 11 This is the battery module 4 as an example. Refer to Figure 11 , in the battery module 4, multiple battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other arbitrary manner. Further, the multiple battery cells 5 can be fixed by fasteners. In some embodiments, the battery module 4 may further include a housing having an accommodation space, and the multiple battery cells 5 are accommodated in the accommodation space.

[0268] In some embodiments, the above battery module 4 can also be assembled into a battery pack 1. The number of battery modules included in the battery pack can be one or more, and those skilled in the art can select a suitable number according to the application and capacity of the battery pack.

[0269] In some embodiments, the battery module 4 may include a battery box body, and the battery box body provides an accommodation space, and the multiple battery cells 5 are accommodated in the accommodation space.

[0270] Figure 12 and Figure 13 This is the battery pack 1 as an example. Refer to Figure 11 and Figure 12 , in the battery pack 1, a battery box body and multiple battery modules 4 arranged in the battery box body can be included. The battery box body includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in the battery box body in any manner.

[0271] The battery cell can be used as the power source of the electrical device or the energy storage unit of the electrical device. The electrical device can include mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but not limited thereto.

[0272] As the electrical device, the battery cell or the battery system can be selected according to its usage requirements.

[0273] Figure 14 This is the electrical device 6 as an example. The electrical device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the electrical device for the battery cell or the battery system, a battery pack or a battery module can be adopted.

[0274] Another example of the electrical device can be a mobile phone, a tablet computer, a laptop computer, etc. This kind of electrical device usually requires being thin and light, and a battery cell or a battery system can be adopted as the power source.

[0275] In still another aspect of the present application, there is provided the use of the aluminum alloy material in the first aspect of the present application in at least one of the preparation of a battery box, a battery cell, a secondary battery, and an electrical device.

[0276] Hereinafter, some embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For those without specified techniques or conditions in the embodiments, they shall be carried out according to the descriptions above, or according to the techniques or conditions described in the literature in the art, or according to the product specifications. For reagents or instruments without specified manufacturers, they are all conventional products that can be obtained through commercial purchase, or can be synthesized from commercially available products in a conventional manner. The same refining agent is used in the following examples.

[0277] In the following embodiments, room temperature refers to 20°C to 30°C.

[0278] I. Preparation of Aluminum Alloy Material

[0279] (I) Preparation Method

[0280] Taking the Mn element as an example, the corresponding ingredients of the Mn element (as shown in Table 1) are denoted as "Mn ingredients".

[0281] (1) First, add pure aluminum ingots to a melting furnace and heat to 730°C to 750°C. After holding for melting, add the Mn ingredients. After the Mn ingredients melt, add the Cu ingredients. When the temperature drops to 700°C to 720°C, add the Si ingredients, a part of the Ti ingredients, the Zn ingredients, and a part of the Sr ingredients for melting. After the above elements melt, add the Mg ingredients at about 720°C. After the Mg ingredients melt, let it stand and skim the slag, add the refining agent, skim the slag again, and then add the remaining Ti ingredients and the remaining Sr ingredients. Finally, obtain an ingot with a preset shape and preset size through casting. Among them, the preset shape and preset size are the sample sizes required for the experiment.

[0282] (2) Let the ingot stand and keep it at 500°C to 600°C for 1.5 h to 2 h, and then cool it to room temperature by water cooling. The obtained aluminum alloy material is a die-cast aluminum alloy sample, which can be used as the main material or component material of a battery box, including but not limited to being used as the main material or component material of a lithium battery box, a fuel cell box, etc.

[0283] (II) Embodiments and Comparative Examples

[0284] Example 1.

[0285] (1) Selection of Alloy Composition

[0286] By mass percentage, the constituent elements of the aluminum alloy material (nominal composition) are: Si: 8.5%, Cu: 0.7%, Ti: 0.3%, Mg: 0.4%, Zn: 0.5%, Mn: 1.0%, Sr: 0.04%, and the balance is Al. Refer to Table 1 for details.

[0287] The ingredient compositions of each element are: AlSi 20 (Si ingredient), AlCu 50 (Cu ingredient), AlTi 5 (Ti ingredient), Zn (Zn ingredient), Mg (Mg ingredient), AlMn 10 (Mn ingredient), AlSr 10 (Sr ingredient) and Al. Taking 1 kilogram (kg) as an example, the burning loss rate of Zn is 12% and that of Mg is 15%.

[0288] (2) Alloy melting

[0289] First, add pure aluminum ingots to the melting furnace and heat to 740 °C. After holding for melting, add the Mn ingredient. After the Mn ingredient melts, add the Cu ingredient. When the temperature drops to 710 °C, add the Si ingredient, Ti ingredient, Zn ingredient, and Sr ingredient for melting. After the above elements melt, add the Mg ingredient. After the Mg ingredient melts, let it stand and skim the slag. Add the refining agent, skim the slag again, add the Ti ingredient and Sr ingredient, and finally obtain ingots through casting.

[0290] (3) Heat treatment

[0291] Keep the ingots static at 550 °C for 2 hours, then water-cool to room temperature to obtain the aluminum alloy material.

[0292] Example 2.

[0293] Prepare aluminum alloy ingots and aluminum alloy materials using a method basically the same as that in Example 1, except that the alloy compositions are different.

[0294] By mass percentage, the constituent elements of the aluminum alloy material (nominal composition) are: Cu: 0.7%, Ti: 0.1%, Mg: 0.5%, Zn: 0.3%, Mn: 0.8%, Sr: 0.04%, and the balance is Al.

[0295] Example 3.

[0296] Prepare aluminum alloy ingots and aluminum alloy materials using a method basically the same as that in Example 1, except that the alloy compositions are different.

[0297] By mass percentage, the constituent elements of the aluminum alloy material (nominal composition) are: Cu: 0.7%, Ti: 0.2%, Mg: 0.4%, Zn: 0.5%, Mn: 0.6%, Sr: 0.04%, and the balance is Al.

[0298] Example 4

[0299] An aluminum alloy ingot and an aluminum alloy material were prepared by substantially the same method as in Example 1, except that step (2) was different.

[0300] Step (2) in Example 4 is as follows: First, pure aluminum ingots are added to a melting furnace and heated to 730 °C. After holding for melting, Mn ingredients are added. After the Mn ingredients are melted, Cu ingredients are added. When the temperature drops to 700 °C, Si ingredients, Ti ingredients, Zn ingredients, and Sr ingredients are added for melting. After the above elements are melted, Mg ingredients are added. After the Mg ingredients are melted, slag is removed by standing. A refining agent is added. After slag removal, Ti ingredients and Sr ingredients are added. Finally, an ingot is obtained by casting.

[0301] Example 5

[0302] An aluminum alloy ingot and an aluminum alloy material were prepared by substantially the same method as in Example 1, except that step (2) was different.

[0303] Step (2) in Example 5 is as follows: First, pure aluminum ingots are added to a melting furnace and heated to 750 °C. After holding for melting, Mn ingredients are added. After the Mn ingredients are melted, Cu ingredients are added. When the temperature drops to 720 °C, Si ingredients, Ti ingredients, Zn ingredients, and Sr ingredients are added for melting. After the above elements are melted, Mg ingredients are added. After the Mg ingredients are melted, slag is removed by standing. A refining agent is added. After slag removal, Ti ingredients and Sr ingredients are added. Finally, an ingot is obtained by casting.

[0304] Example 6

[0305] An aluminum alloy ingot and an aluminum alloy material were prepared by substantially the same method as in Example 1, except that step (3) was different.

[0306] Step (3) in Example 6 is as follows: The ingot is allowed to stand and held at 500 °C for 1.75 h, and then water-cooled to room temperature to obtain an aluminum alloy material.

[0307] Example 7

[0308] An aluminum alloy ingot and an aluminum alloy material were prepared by substantially the same method as in Example 1, except that step (3) was different.

[0309] Step (3) in Example 7 is as follows: The ingot is allowed to stand and held at 600 °C for 2.25 h, and then water-cooled to room temperature to obtain an aluminum alloy material.

[0310] Example 8

[0311] The aluminum alloy ingot and aluminum alloy material were prepared by substantially the same method as in Example 1, except that step (3) was different.

[0312] Step (3) of Example 8 is as follows: The ingot was allowed to stand and heat-insulated at 450 °C for 2 h, and then water-cooled to room temperature to obtain the aluminum alloy material.

[0313] Example 9.

[0314] The aluminum alloy ingot and aluminum alloy material were prepared by substantially the same method as in Example 1, except that step (3) was different.

[0315] Step (3) of Example 9 is as follows: The ingot was allowed to stand and heat-insulated at 550 °C for 1.25 h, and then water-cooled to room temperature to obtain the aluminum alloy material.

[0316] Comparative Example 1.

[0317] The aluminum alloy ingot and aluminum alloy material were prepared by substantially the same method as in Example 1, except that the alloy composition for preparing the aluminum alloy ingot was different.

[0318] By mass percentage, the composition elements of the aluminum alloy material are (nominal composition): Si: 7.5%, Cu: 3.0%, Mg: 0.1%, Zn: 0.2%, Mn: 0.02%, Fe: 0.7%, and the balance is Al.

[0319] Comparative Example 2.

[0320] The aluminum alloy ingot and aluminum alloy material were prepared by substantially the same method as in Example 1, except that step (2) was different.

[0321] Step (2) of Comparative Example 2 is as follows: First, the pure aluminum ingot was added to the melting furnace and heated to 800 °C. After heat-insulated and melted, the Mn ingredient was added. After the Mn ingredient melted, the Cu ingredient was added. When the temperature dropped to 750 °C, the Si ingredient, Ti ingredient, Zn ingredient, and Sr ingredient were added for melting. After the above elements melted, the Mg ingredient was added. After the Mg ingredient melted, it was allowed to stand and slag was skimmed off. The refining agent was added. After skimming off the slag, the Ti ingredient and Sr ingredient were added. Finally, the ingot was obtained by casting.

[0322] Comparative Example 3.

[0323] The aluminum alloy ingot and aluminum alloy material were prepared by substantially the same method as in Example 1, except that the alloy composition was substantially the same as that of A380 aluminum alloy.

[0324] The nominal compositions of the aluminum alloy materials in each example and comparative example can be seen in Table 1.

[0325] Table 1.

[0326]

[0327] For the chemical composition of the A380 aluminum alloy in Comparative Example 3, refer to Table 2.

[0328] Table 2. Elemental composition of A380 aluminum alloy

[0329]

[0330] In Table 2, " / " indicates that the element component is not actively added.

[0331] II. Test analysis methods

[0332] (I) Actual composition analysis

[0333] An inductively coupled plasma emission spectrometer (ICP instrument, Avio 5000) was used for elemental analysis to accurately measure the actual composition of the aluminum alloy material.

[0334] (II) Microstructure analysis

[0335] 1. Phase analysis

[0336] X-ray diffraction (XRD) was used to detect the phases with higher contents.

[0337] XRD test instrument and parameters: D8 Advance Da Vinci X, Cu Kα1, scanning range 20° - 110°, scanning speed 5° / minute.

[0338] It should be noted that during XRD phase detection, obvious diffraction peaks will only appear when the phase content is greater than 5 wt%. Low-content alloy phases with a content not exceeding 5% are analyzed by an energy dispersive spectrometer (EDS).

[0339] FESEM+EDS test instrument and parameters: field emission scanning electron microscope FEI NOVA NanoSEM 230, English name "FESEM+EDS", probe type (det) is ETD, acceleration voltage (HV) is 15 kV. The remaining parameters can be taken as an example in Figure 3 For example, Figure 3 in, the magnification (mag) is 1000 times (1000X), the working distance (WD) is 6.5 millimeters (mm), the image width (HFW) is 298 micrometers (μm), and the beam spot diameter (spot) is 5.5 nanometers (nm). The obtained image can also be recorded as a SEM-EDS image.

[0340] 2. Metallographic structure analysis

[0341] Instruments and test parameters: CX40M metallographic microscope, with magnification multiples including 25x, 100x, 20x, 200x, 500x, and 1000x. Other magnification multiples can also be selected.

[0342] 3. Analysis method for the mass fraction of different alloy phases:

[0343] Jmatpro simulation calculation.

[0344] (III) Mechanical property testing and corrosion detection

[0345] For the aluminum alloy materials prepared in Examples 1 - 9 and Comparative Examples 1 - 3, hardness testing, tensile testing, and corrosion testing were carried out with reference to the method of "GB / T 4340.1 - 1999 Metallic materials - Vickers hardness test - Part 1: Test method".

[0346] 1. Hardness testing

[0347] Instrument: Hardness tester.

[0348] Test parameters: Loading load 0.1 kg.

[0349] 2. Tensile testing:

[0350] (1) Sample size, as Figure 10 shown, with the unit of millimeter (mm), where R2.5 represents a radius of 2.5 millimeters.

[0351] (2) Test instrument: Z20 universal electronic testing machine.

[0352] (3) Test analysis method:

[0353] Wrap the tensile samples of the aluminum alloy material with blue film, leaving only the test surface. The total test duration is 600 h. During the test, a batch of samples is taken every 24 h for tensile property testing, and at least three parallel samples are set for each test.

[0354] Mechanical property testing is carried out on the tensile specimens at different corrosion stages to obtain the stress - strain curve, and then the tensile strength (which can be abbreviated as UTS, or also referred to as tensile strength or ultimate tensile strength), elongation (which can be abbreviated as El), and yield strength (which can be abbreviated as YS) are analyzed. The larger the elongation, the better the ductility of the material.

[0355] 3. Corrosion test

[0356] (1) Electrochemical corrosion test

[0357] Electrochemical corrosion includes: open circuit voltage test, alternating current impedance test, and potentiodynamic polarization test.

[0358] Test solution: 3.5 wt% aqueous NaCl solution.

[0359] Before the test, cut the die-cast aluminum alloy into samples with dimensions of 10 mm × 10 mm × 2 mm, and cold mount the samples with epoxy resin to ensure that only the test surface with an area of 1 cm 2 is exposed after cold mounting. The test surface is also polished successively with sandpaper and then polished with a polishing agent until the surface of the sample is clean and bright. After cleaning the surface with ethanol, it is dried for standby.

[0360] During the test, first measure the open circuit voltage (OCP) of the sample. After the OCP is stable for 60 min, perform an alternating current impedance test (EIS) on the sample to measure the electrochemical impedance spectrum of the sample at different alternating current frequencies. When testing, use a 10 mV alternating current sine wave as the excitation voltage, and control the test frequency within 0.01 Hz to 105 Hz.

[0361] After the test, fit the results of the EIS with an equivalent circuit and analyze the parameters of each component in the equivalent circuit diagram. After performing the alternating current impedance experiment, perform a potentiodynamic polarization test on the sample. Starting from the potential of OCP - 300 mV, scan at a scanning rate of 0.167 mV / s until the current is greater than 1 mA. After the test, use ZSimpWin v3.40 software to perform Tafel fitting on the polarization characteristics of the sample.

[0362] (2) Salt spray corrosion test

[0363] Use 3.5 wt% aqueous NaCl solution for testing at 35 °C.

[0364] Every 24 h, analyze the macroscopic morphology, microscopic morphology, corrosion mass loss, and corrosion rate from the box materials with a total test time of 600 h.

[0365] Before the test, wrap the non-test surface of the 15 mm × 15 mm × 2 mm block-shaped aluminum alloy sample with blue film. Polish, polish, and dry the test surface and then weigh it as W0. The total test duration is 600 h. During the test, take a batch of samples every 24 h for observation of the macroscopic and microscopic morphologies. After observation, use chromic acid cleaner (20 g / L Cr 2 O 3 + 50 mL / L H 3 PO 4 ) to remove the corrosion products on the surface of the sample and weigh it again to calculate the corrosion rate and perform morphology observation. The test duration of the i-th sampling is denoted as Ti, and the weighing at the i-th sampling is denoted as Wi. Set at least three parallel samples for each test.

[0366] (A) Macroscopic morphology test method

[0367] Sample: The sampled corrosion time points are as described above.

[0368] Instrument: CX40M metallographic microscope. The aforementioned test method can be adopted.

[0369] (B) Microscopic morphology test method

[0370] Sample: The sampled corrosion time points are as described above.

[0371] Instrument: FEI NOVA NanoSEM 230. The aforementioned test method can be adopted.

[0372] (C) Corrosion mass loss and corrosion rate analysis method

[0373] The mass loss W of the i-th sampling = W0 - Wi.

[0374] The corrosion rate Ri at the i-th sampling can be calculated by substituting into formula (I):

[0375] Corrosion rate = (K × W) / (A × Ti × D) mm / y (I)

[0376] In formula (I): K = 8.64×10 4 , K is the time constant;

[0377] W is the mass difference before and after the test = W0 - Wi, with the unit of mg;

[0378] A is the test surface area 2.25 cm 2 , with the unit of cm 2 ;

[0379] Ti is the test time of the i-th sampling, with the unit of h;

[0380] D = 2.7 g / cm 3 , D is the material density.

[0381] "mm / y" represents millimeters per year.

[0382] (3) Immersion corrosion test

[0383] Use a 3.5 wt% NaCl aqueous solution.

[0384] The stage immersion corrosion includes analyzing the macroscopic morphology, microscopic morphology, and corrosion rate from the box material with a total test time of 30 d every 10 d. In the application, 1 d = 1 day.

[0385] The sample for the immersion corrosion test can be a block of 15 mm × 15 mm × 2 mm.

[0386] Before the test, the test surface was polished, and then rinsed successively with deionized water and ethanol. After drying and weighing, the specimens were placed in a desiccator for storage and standby. During the test, the samples were placed in a container, and 500 mL of corrosion solution was added. The composition of the corrosion solution was: 3.5 wt% aqueous NaCl solution. After sealing, the whole container was placed in a constant temperature water bath tank, and the temperature was set at 25 °C. Specimens were taken every 10 d (i.e., the test times were 10 d, 20 d, and 30 d), and the macroscopic and microscopic morphologies of the sample surface after corrosion were observed. Subsequently, the corrosion products on the sample surface were removed, the masses of the samples before and after corrosion were compared, and the corresponding immersion corrosion rate was calculated. Three parallel samples were set for each test.

[0387] III. Analysis of Test Results

[0388] In Example 1, the experimental group was also denoted as "N1", and the prepared aluminum alloy material was also denoted as N1 alloy.

[0389] (I) Comparison between Nominal Composition and Actual Composition

[0390] Taking Example 1 as an example, the ICP test results showed that the actual composition of the aluminum alloy material was very close to its nominal composition, indicating good melting effect. Refer to Table 3.

[0391] Table 3. Nominal Composition and Actual Composition of Aluminum Alloy Material in Example 1

[0392]

[0393] The element contents in Table 3 refer to the mass percentage contents in the aluminum alloy material, with the unit of wt%.

[0394] (II) Phase Analysis

[0395] It is described taking Example 1 as an example.

[0396] The metallographic structure of the aluminum alloy material prepared in Example 1 can be referred to Figure 1 . Among them, the α-Al matrix phase was mainly distributed in the form of near equiaxed crystals, the eutectic Si phase was distributed in the form of fine fibrous tissues between α-Al grains, and there were also a small amount of other alloy phases. Due to the addition of a small amount of Sr for modification, the eutectic Si phase in the aluminum alloy material of Example 1 was transformed into fibrous and granular morphologies, different from the Al-Si eutectic structure in the A380 aluminum alloy of Comparative Example 3. Due to the significant reduction of the Cu content in the alloy, no Al 2 Cu phase similar to that in the A380 alloy was observed. Due to the low contents of Mg and Zn, no obvious Mg 2 Si phase was observed either. In addition, some round or elliptical Ti-rich phases (Al 3Ti phase), acicular AlSiMnFe phase or multi-branched Mn-rich phase (AlSiMnFeCu phase).

[0397] The XRD pattern of the aluminum alloy material in Example 1 can be referred to Figure 2 , and the diffraction peaks in the figure are mainly the α-Al matrix phase and the Si phase, and no other alloy phases are detected, indicating that the content of the remaining alloy phases is small. According to Figure 1 , the ratio of the Si phase to the α-Al matrix phase is about 1:(8-9).

[0398] Figure 3 shows the microstructure and element distribution of the aluminum alloy material in Example 1. The microstructure and element distribution of the aluminum alloy material in Example 1 can be referred to Figure 4 SEM-EDS images. The Ti element is circular or elliptical in the SEM image, which is the circular or elliptical alloy phase observed in the metallographic structure, and its composition is Al 3 Ti, which is a strengthening phase; the Si element is fibrous or granular in the SEM image, indicating that the modification effect of Sr is very obvious. In addition, for the metallographic EDS point scanning analysis of the acicular and multi-branched alloy phases, it can be referred to Figure 4 and Table 4. The acicular phase is the AlSiMnFe phase, and the multi-branched phase is the AlSiMnFe phase containing Cu (i.e., the AlSiMnFeCu phase). The addition of Cu makes the acicular AlSiMnFe phase larger and some slender branches appear.

[0399] Table 4. Figure 4 EDS point chemical composition table of the aluminum alloy material in Example 1 in

[0400] Element type Element content at P1 position (wt%) Element content at P2 position (wt%) Element content at P3 position (wt%) Al 80.10 80.06 77.89 Si 6.25 5.63 6.42 Mn 10.59 10.44 11.77 Fe 3.06 2.00 2.18 Cu - 1.87 1.74

[0401] The "-" in Table 4 indicates that it was not detected.

[0402] Through simulation calculation, the mass fractions of several different alloy phases in each example respectively meet:

[0403] (1) The mass fraction of the Al 2 Cu phase in the aluminum alloy material is ≤1.3, and it also meets 0.1% - 1.3%; among them, Example 1 also meets 0.8% - 1.3%.

[0404] (2) The mass fraction of the Al 3 Ti strengthening phase in the aluminum alloy material meets 0.3% - 2%, and it also meets 0.3% - 1%; among them, Example 1 also meets 0.35% - 0.6%.

[0405] (3) The mass fraction of the AlSiMnFe phase in the aluminum alloy material meets ≤0.2%, and it also meets ≤0.1%.

[0406] (4) Mg 2 The mass fraction of Si phase in the aluminum alloy material satisfies ≤ 0.05%, and it cannot be detected, so it can be basically regarded as 0%.

[0407] (III) Mechanical property tests and corrosion tests

[0408] According to the test results of mechanical property tests and corrosion tests, each of Examples 1-9 has good mechanical properties and excellent corrosion resistance, which are significantly better than those of Comparative Examples 1-3.

[0409] Taking Example 1 as an example, the test analysis results of each example are described.

[0410] Figure 5 are the curves of the mass fraction, elastic modulus, thermal conductivity and density of A380 aluminum alloy and the aluminum alloy material (N1 alloy) in Example 1 changing with temperature, obtained by Jmatpro analysis; among them, the mass fraction refers to the mass fraction of the aluminum alloy material at different temperatures relative to the initial mass of the aluminum alloy material in the unheated state, reflecting the thermal weight loss of the aluminum alloy material. The solid-liquid temperature range of N1 alloy is basically similar to that of A380 alloy, which is 480 °C - 630 °C; the elastic modulus of N1 alloy is slightly higher than that of A380 alloy, which is 75.37 GPa at room temperature; the thermal conductivity of N2 alloy is higher than that of A380 alloy, which is 160.94 W / m·K at room temperature; the density of N1 alloy is lower than that of A380 alloy, which is 2.71 g / cm 3 .

[0411] The results of the alternating current impedance test of the aluminum alloy material of Example 1 (also denoted as N1) can be referred to Figure 6 . Compared with A380 alloy (Comparative Example 3), whether it is at low frequency or high frequency, the aluminum alloy material of Example 1 shows higher impedance and phase angle, which can be referred to Figure 6 in (a) and (b)). Although the impedance of A380 alloy gradually approaches that of the aluminum alloy material of Example 1 at low frequency, it is still smaller than its impedance. In the Nyquest plot ( Figure 6 in (c)), the aluminum alloy material of Example 1 and A380 alloy show similar capacitance loop patterns. However, the diameter of the capacitance loop of the aluminum alloy material of Example 1 is larger, indicating that it has better capacitance performance and higher charge transfer resistance. Fitting with the equivalent circuit shown in Figure 7 , the results are shown in Table 5. Whether it is R sl or R ct of the alloy of the aluminum alloy material of Example 1 is higher than that of A380 alloy, indicating that it has better corrosion resistance.

[0412] In the equivalent circuit Figure 7 , R sRepresents the solution resistance related to the corrosion solution used in the experiment, R sl , R ct respectively represent the surface resistance and charge transfer resistance of each alloy as the working electrode. In addition, the deviation of the capacitance in EIS from the ideal capacitance behavior is represented by the constant phase element (CPE), and n is used as an index to evaluate the closeness between the actual experiment and the theoretical calculation. Q 1 and Q 2 respectively represent the capacitances of the surface layer and the charge transfer layer during the establishment of the corrosion cell, corresponding to n1 and n2 respectively.

[0413] Table 5. EIS equivalent circuit parameter table of the aluminum alloy material in Example 1 and the A380 alloy in Comparative Example 3

[0414] Parameter <![CDATA[R s / Ω]]> <![CDATA[Q 1 / μF]]> <![CDATA[n 1 > <![CDATA[R sl / kΩ]]> <![CDATA[R ct / kΩ]]> <![CDATA[Q 2 / μF]]> <![CDATA[n 2 > Aluminum alloy material of Example 1 10.46 113.7 0.942 6.27 7.06 13.2 0.935 A380 12.37 91.4 0.985 4.67 5.59 12.5 0.965

[0415] The potentiodynamic polarization curve of the aluminum alloy material in Example 1 can be referred to Figure 8 , the abscissa is the chemical potential (unit: V), and the ordinate is the current density (A / cm 2 ).

[0416] The potentiodynamic polarization curves of the aluminum alloy material (N1 alloy) in Example 1 and the A380 alloy are similar, and the N1 alloy also does not show passivation. Although the corrosion potential (E corr ) of the N1 alloy is lower than that of the A380 alloy, the corrosion current density (I corr ) of the N1 alloy is only 46.9% of that of the A380 alloy, and its polarization resistance (R p ) is also higher. Therefore, its corrosion resistance is better than that of the A380 alloy.

[0417] The macroscopic surface morphology diagrams of the alloy material (N1 alloy) in Example 1 at different corrosion times in the salt spray corrosion test can be referred to Figure 9 . The corrosion rate of the alloy material (N1 alloy) in Example 1 is much lower than that of the A380 alloy, indicating that the N1 alloy has better corrosion resistance.

[0418] According to the results of the immersion corrosion test, at the corrosion times of 10 d, 20 d, and 30 d, the corrosion rates of the alloy material (N1 alloy) in Example 1 are only 41.3%, 49%, and 50.5% of that of the A380 alloy respectively, indicating that it has very excellent corrosion resistance compared with the A380 alloy.

[0419] According to the tensile test results, the tensile strength of the aluminum alloy material in Example 1 (aluminum alloy N1) is improved compared with that of A380 alloy, and the elongation rate reaches 5.42%, which is more than 2.5 times that of A380 alloy under the same treatment conditions. After 15 days of corrosion, the elongation rate of alloy N1 is still higher than that of A380 alloy; when corroded for 25 days, the elongation rate can still reach 77.8% of A380 alloy. At the same corrosion time, the strength and elongation rate of A380 alloy are lower than those of the new alloy N1, indicating that the mechanical properties and corrosion resistance of the new alloy are better than those of A380 alloy. Please refer to Table 6.

[0420] Table 6. Comparison of mechanical properties between the aluminum alloy material in Example 1 (aluminum alloy N1) and Comparative Example 3 (aluminum alloy A380)

[0421]

[0422] The analysis results of the mechanical property tests and corrosion rates of each example and each comparative example are also summarized in Table 7.

[0423] Table 7.

[0424]

[0425] Taking Comparative Example 3 as an example, the test analysis results of each comparative example are described.

[0426] In Comparative Example 3, the A380 alloy is mainly composed of columnar or near-equiaxed α-Al matrix phase and fine Al-Si eutectic structure. In addition, there are some bone-shaped or needle-shaped alloy phases near the eutectic structure. A part of the Cu element in the A380 alloy is dissolved in the α-Al matrix; the other part forms bone-shaped or needle-shaped Cu-rich phases, which are analyzed as Al 2 Cu phase.

[0427] For the salt spray corrosion test of A380 die-cast aluminum alloy (Comparative Example 3), the macroscopic surface morphology of the sample at different corrosion times. The corrosion of A380 alloy is relatively serious, and there are more white corrosion products accumulated on the sample. Due to the occurrence of general corrosion, the alloy surface is quickly covered by corrosion products at a relatively short corrosion time (1-6 days). Subsequently, the stacking area and thickness of the surface corrosion products both increase continuously with the extension of the corrosion time, and the sample surface shows the characteristic of transitioning from the initially corroded dark color to being covered by a large amount of white corrosion products.

[0428] The microscopic tissue results of A380 die-cast aluminum alloy (Comparative Example 3) in the early and late stages of the salt spray corrosion test show that the A380 alloy exhibits a general and uniform corrosion morphology, and the corrosion of the A380 alloy is relatively serious with more corrosion products. There are more and thicker corrosion products on the surface of the A380 alloy.

[0429] The results of the microstructure of the die-cast aluminum alloy after removing the corrosion products of A380 die-cast aluminum alloy (Comparative Example 3) show that a large number of corrosion pits are distributed around the Al-Si eutectic structure of the A380 alloy because Al 2 The Al-Cu phase is distributed near the Al-Si eutectic structure, further exacerbating the intergranular corrosion tendency of the Al-Si eutectic structure. In addition, the solid solution of a small amount of Cu in the matrix will increase the potential difference between the grain boundaries and the grain interior, and Al 2 The potential of the Cu phase is relatively positive. At the same time, the potential of the matrix phase with a higher Cu content is also relatively positive. At this time, the matrix with a lower Cu content will act as the cathode phase, together with the nearby Cu-rich matrix phase and Al 2 The Cu phase forms an electrochemical microcell locally, causing the matrix phase of the Cu-poor solid solution to corrode continuously, resulting in the disappearance of the grain boundaries.

[0430] The analysis results of the mass loss and the corresponding corrosion rate of the A380 die-cast aluminum alloy (Comparative Example 3) under different salt spray corrosion times show that both the corrosion weight loss and the corrosion rate of the A380 alloy are relatively high.

[0431] According to the test analysis results of the tensile test, analyzing the change trend of the mechanical properties and the corrosion time, it is found that the yield strength and the tensile strength of the A380 alloy (Comparative Example 3) show a rapid downward trend with the increase of the corrosion time, which is particularly obvious in the initial stage of corrosion (1-4d). The yield strength and the tensile strength decrease to 77.5% and 76% of that before corrosion respectively; subsequently, the attenuation rate of its performance slows down, and finally the yield strength and the tensile strength decrease to 65.4% and 52.5% of that before corrosion respectively.

[0432] The descriptions of the above embodiments tend to emphasize the differences between the embodiments. Their similarities or similarities can be referred to each other. For the sake of brevity, they will not be elaborated in this article.

[0433] The technical features of the above-described embodiments or examples can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments or examples are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0434] It should be noted that this application is not limited to the above-mentioned embodiments and examples. The above-mentioned embodiments and examples are only for illustration, and any embodiments with the same composition and the same effect within the scope of the technical solution of this application and with the same technical idea are included in the technical scope of this application. The above embodiments and examples only represent several embodiments of this application, and their descriptions are relatively detailed, but they should not be construed as limitations on the scope of the patent. In addition, within the scope of not departing from the gist of this application, various modifications that can be conceived by those skilled in the art to the above embodiments or examples, and other ways constructed by combining some of the constituent elements in the embodiments or examples are also included in the scope of this application.

Claims

1. An aluminum alloy material, characterized in that, by mass percentage, the aluminum alloy material comprises the following constituent elements: 6% - 11% of Si, 0.5% - 0.9% of Cu, 0.1% - 0.4% of Ti, 0.2% - 0.6% of Mg, 0.25% - 0.6% of Zn, 0.5% - 1.1% of Mn, 0.01% - 0.05% of Sr, matrix element Al and inevitable impurity elements; Among them, the aluminum alloy material includes or does not include Al 2 Cu phase, and the mass fraction of the Al 2 Cu phase in the aluminum alloy material is ≤ 1.3%.

2. The aluminum alloy material according to claim 1, characterized in that, meeting one or two of the following characteristics: the mass percentage of Cu element in the aluminum alloy material is 0.5% - 0.8%; The aluminum alloy material includes Al 2 Cu phase, and the mass fraction of the Al 2 Cu phase in the aluminum alloy material is 0.1% to 1.3%.

3. The aluminum alloy material according to claim 1 or 2, characterized in that, meeting one or two of the following characteristics: the mass percentage of Cu element in the aluminum alloy material is 0.6% - 0.8%; The aluminum alloy material includes Al 2 Cu phase, and the mass fraction of the Al 2 Cu phase in the aluminum alloy material is 0.8% to 1.3%.

4. The aluminum alloy material according to any one of claims 1 - 3, characterized in that, the aluminum alloy material comprises fibrous Al - Si eutectic structure; The aluminum alloy material includes Al 3 Ti strengthening phase.

5. The aluminum alloy material according to claim 4, characterized in that, meeting one, two or three of the following characteristics: the mass percentage of Si element in the aluminum alloy material is 6.5% - 11%; the mass percentage of Ti element in the aluminum alloy material is 0.2% - 0.4%; The Al 3 The mass fraction of the Ti strengthening phase in the aluminum alloy material is 0.3% to 2%.

6. The aluminum alloy material according to claim 4 or 5, characterized in that, meeting one, two or three of the following characteristics: the mass percentage of Si element in the aluminum alloy material is 8% - 11%; the mass percentage of Ti element in the aluminum alloy material is 0.25% - 0.4%; The Al 3 Ti strengthening phase has a mass fraction of 0.3% to 1% in the aluminum alloy material, and can be optionally 0.35% to 0.6%.

7. The aluminum alloy material according to any one of claims 1 - 6, characterized in that, The aluminum alloy material includes or does not include Mg 2 Si phase, and the mass fraction of the Mg 2 Si phase in the aluminum alloy material is ≤ 0.05%, and can be optionally 0%.

8. The aluminum alloy material according to claim 7, characterized in that, meeting one or two or three of the following characteristics: the mass percentage of Mg element in the aluminum alloy material is 0.3% - 0.6%; the mass percentage of Zn element in the aluminum alloy material is 0.3% - 0.6%; the mass ratio of Mg element and Zn element in the aluminum alloy material is 1:(1.1 - 1.3).

9. The aluminum alloy material according to claim 7 or 8, characterized in that, meeting one or two of the following characteristics: the mass percentage of Mg element in the aluminum alloy material is 0.3% - 0.5%; the mass percentage of Zn element in the aluminum alloy material is 0.4% - 0.6%; the mass ratio of Mg element and Zn element in the aluminum alloy material is 1:(1.1 - 1.25).

10. The aluminum alloy material according to any one of claims 1 - 9, characterized in that, the inevitable impurity elements include Fe element.

11. The aluminum alloy material according to any one of claims 1 - 10, characterized in that, meeting one or two of the following characteristics: the mass percentage of Mn element in the aluminum alloy material is 0.7% - 1.1%, optionally 0.8% - 1.1%; The aluminum alloy material includes an AlSiMnFe phase, and the mass fraction of the AlSiMnFe phase in the aluminum alloy material is ≤0.2%, optionally ≤0.1%; optionally, the aluminum alloy material includes an AlSiMnFe phase.

12. The aluminum alloy material according to any one of claims 1 to 11, characterized in that the mass proportion of Sr element in the aluminum alloy material is 200 ppm to 500 ppm.

13. The aluminum alloy material according to any one of claims 1 to 12, characterized in that by mass percentage, the aluminum alloy material includes the following constituent elements: 6% to 11% of Si, 0.5% to 0.9% of Cu, 0.1% to 0.4% of Ti, 0.3% to 0.6% of Mg, 0.3% to 0.6% of Zn, 0.5% to 1.1% of Mn, 0.01% to 0.05% of Sr, the inevitable impurity elements and the balance of the matrix element Al.

14. The aluminum alloy material according to claim 13, characterized in that by mass percentage, the aluminum alloy material includes the following constituent elements: 6.5% to 11% of Si, 0.5% to 0.8% of Cu, 0.2% to 0.4% of Ti, 0.3% to 0.6% of Mg, 0.3% to 0.6% of Zn, 0.7% to 1.1% of Mn, 0.02% to 0.05% of Sr, the inevitable impurity elements and the balance of the matrix element Al.

15. The aluminum alloy material according to claim 13, characterized in that by mass percentage, the aluminum alloy material includes the following constituent elements: 8% to 11% of Si, 0.6% to 0.8% of Cu, 0.25% to 0.4% of Ti, 0.3% to 0.5% of Mg, 0.4% to 0.6% of Zn, 0.8% to 1.1% of Mn, 0.03% to 0.05% of Sr, the inevitable impurity elements and the balance of the matrix element Al.

16. An aluminum alloy structural member, characterized in that the aluminum alloy structural member is a formed body of the aluminum alloy material according to any one of claims 1 to 15.

17. A preparation method of an aluminum alloy structural member, characterized in that comprises the following steps: heating and melting aluminum ingots, adding ingredients determined according to the nominal composition of the aluminum alloy material according to any one of claims 1 to 15 in the form of master alloys, performing melting and refining and slag skimming to prepare an aluminum alloy refined melt, casting and molding the aluminum alloy refined melt to prepare an aluminum alloy ingot; performing heat treatment on the aluminum alloy ingot and cooling to obtain the aluminum alloy structural member.

18. A battery box, characterized in that the battery box satisfies at least one of the following characteristics: at least a part of the structural members in the battery box contain the aluminum alloy material according to any one of claims 1 to 15; the battery box includes the aluminum alloy structural member according to claim 16; and the battery box includes an aluminum alloy structural member prepared by the preparation method of the aluminum alloy structural member according to claim 17.

19. A battery system, It is characterized in that the battery system includes the battery box described in claim 18 and battery cells located inside the battery box.

20. The battery system according to claim 19, it is characterized in that the battery cells include a liquid electrolyte.

21. An electrical device, it is characterized in that it includes at least one of the aluminum alloy materials described in any one of claims 1 to 15, the aluminum alloy structural member described in claim 16, the aluminum alloy structural member prepared by the preparation method of the aluminum alloy structural member described in claim 17, the battery box described in claim 18, and the battery system described in claim 19 or 20.

22. Use of the aluminum alloy material described in any one of claims 1 to 15 in the preparation of at least one of an aluminum alloy structural member, a battery box, a battery system, and an electrical device.

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