Aluminum alloy material, aluminum alloy structural part and preparation method therefor, battery box body, battery system, electric device and use

Abstract

An aluminum alloy material, an aluminum alloy structural part and a preparation method therefor, a battery box body, a battery system, an electric device (6) and the use. The aluminum alloy material comprises, in percentages by mass, silicon, copper, titanium, magnesium, zinc, manganese, strontium, a matrix element Al and inevitable impurity elements; and the aluminum alloy material does not contain or has a relatively low content of an Al2Cu phase.

Description

Aluminum alloy material, aluminum alloy structural part and preparation method thereof, battery box, battery system, electrical device and application thereof

[0001] Related applications

[0002] This application claims priority to Chinese patent application number CN2023116079934, filed on November 27, 2023, entitled “Aluminum alloy materials, aluminum alloy structural parts and preparation methods thereof, battery cases, battery systems, electrical devices and applications,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the technical field of aluminum alloy materials, further to the technical field of battery case materials, and further to aluminum alloy materials, aluminum alloy structural parts and preparation methods thereof, battery cases, battery systems, electrical devices and applications. Background Art

[0004] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0005] The battery case is a key component of the battery and plays an important role in protecting it. For batteries containing electrolyte, the case must not only have good mechanical properties to reduce damage to the battery during impact, but also exhibit a certain degree of corrosion resistance to extend the battery's service life. The corrosion resistance of current aluminum alloy materials needs to be further improved.

[0006] Summary of the Invention

[0007] According to various embodiments and examples of the present application, an aluminum alloy material, an aluminum alloy structural member, a method for preparing the same, a battery case, a battery system, an electrical device, and applications thereof are provided. The aluminum alloy material exhibits excellent mechanical properties and corrosion resistance and can be used as the primary material for the battery case, thereby extending the battery case's service life.

[0008] In the first aspect, the present 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 the aluminum alloy material does not contain Al2Cu phase or the content is low, for example, the mass fraction of Al2Cu phase in the aluminum alloy material is low (e.g., ≤1.3%).

[0009] In some embodiments, the aluminum alloy material includes the following constituent elements: 6% to 11% Si, 0.5% to 0.9% Cu, 0.1% to 0.4% Ti, 0.2% to 0.6% Mg, 0.25% to 0.6% Zn, 0.5% to 1.1% Mn, 0.01% to 0.05% Sr, matrix element Al and unavoidable impurity elements; the aluminum alloy material does not contain Al2Cu phase or the content is low, for example, the Al2Cu phase content is ≤1.3%. In some embodiments, an aluminum alloy material is provided, wherein the aluminum alloy material comprises the following constituent elements by mass percentage: 6% to 11% Si, 0.5% to 0.9% Cu, 0.1% to 0.4% Ti, 0.2% to 0.6% Mg, 0.25% to 0.6% Zn, 0.5% to 1.1% Mn, 0.01% to 0.05% Sr, matrix element Al, and unavoidable impurity elements;

[0010] The aluminum alloy material may include or exclude an Al2Cu phase. Optionally, the mass fraction of the Al2Cu phase in the aluminum alloy material is ≤1.3%.

[0011] The aluminum alloy material uses aluminum (Al) as a matrix element and includes silicon (Si), copper (Cu), titanium (Ti), magnesium (Mg), zinc (Zn), manganese (Mn) and strontium (Sr). The composition of the aluminum alloy material is controlled within the aforementioned content range. The matrix element Al in the aluminum alloy material forms an α-Al matrix phase, which is mainly distributed in a morphology close to an equiaxed crystal. 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-like or needle-like Al2Cu phase, which 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 impurity phase morphology and thereby reduce the damage of the impurity phase to the mechanical properties, a high content of Cu element can easily lead to a decrease in the corrosion resistance of the aluminum alloy material and also reduce the elongation of the aluminum alloy material. The potential of the Al2Cu 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 a cathode phase, and locally form an electrochemical microbattery with the nearby Cu-rich matrix phase and Al2Cu phase, so that the matrix phase part of the Cu-poor solid solution is continuously corroded. The content of Al2Cu is basically linearly related to the Cu content. By designing a relatively low copper content, the proportion of the Al2Cu 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 element, it is possible to produce a strengthening effect while having no adverse effect or a small effect on the corrosion resistance. By introducing the Ti element, a circular or nearly elliptical precipitate phase can be formed. The precipitate phase can serve as a non-spontaneous nucleation site during crystallization, has a certain grain refining effect, and can play a strengthening role and improve the elongation. The introduction of Mg and Zn elements can improve the strength of the aluminum alloy material by forming a solid solution and precipitation strengthening. The Sr element is soluble in the matrix phase and can alter the solidification process during casting, modifying the alloy phase of the aluminum alloy material. It can modify the Al-Si eutectic structure into fine fibers, thereby improving mechanical strength. The Mn element can complement the strengthening effect of the Mg element and make the precipitate phase uniformly distributed. In addition, the introduction of the Mn element facilitates the demolding process of casting and can combine with impurity elements to reduce the damage caused by 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 unique microstructure. The multiple synergistic effects between the various elements can effectively improve the corrosion resistance of the aluminum alloy material while also giving the aluminum alloy material good mechanical properties, with both mechanical strength and ductility improved.By rationally setting the content of elements such as Cu, Mg, and Zn, the foundation can be laid for aluminum alloy materials to have good mechanical properties such as tensile strength and hardness. By controlling the content of Cu, Ti, and Sr in aluminum alloy materials, the corrosion resistance of aluminum alloy materials can be significantly improved.

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

[0013] The mass percentage of Cu element in the aluminum alloy material is 0.5% to 0.8%;

[0014] The aluminum alloy material includes an Al2Cu phase, and the mass fraction of the Al2Cu phase in the aluminum alloy material is 0.1% to 1.3%.

[0015] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material satisfies one or both of the following characteristics:

[0016] The mass percentage of Cu element in the aluminum alloy material is 0.6% to 0.8%;

[0017] The aluminum alloy material includes an Al2Cu phase, and the mass fraction of the Al2Cu phase in the aluminum alloy material is 0.8% to 1.3%.

[0018] The Al2Cu phase content can be controlled by adjusting the mass percentage of Cu in the aluminum alloy. Controlling the Al2Cu phase content within the aforementioned range is more conducive to achieving good mechanical properties and excellent corrosion resistance in the aluminum alloy. Furthermore, it is more conducive to achieving excellent corrosion resistance while also providing the aluminum alloy with good mechanical strength and ductility.

[0019] Based on any appropriate 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 an Al3Ti strengthening phase.

[0020] In aluminum alloys, the α-Al matrix and Si phase form an Al-Si eutectic phase. This eutectic phase is primarily distributed as fine fibrous structures between the α-Al grains, which helps improve the mechanical strength of the matrix phase. Ti can form round or nearly elliptical Al3Ti precipitates, which serve as non-spontaneous nucleation sites during crystallization, exerting a certain grain-refining effect and contributing to strengthening. Furthermore, improved distribution of the secondary phase and grain refinement strengthen the alloy, which in turn contribute to improved ductility.

[0021] 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:

[0022] The mass percentage of Si element in the aluminum alloy material is 6.5% to 11%;

[0023] The mass percentage of Ti element in the aluminum alloy material is 0.2% to 0.4%;

[0024] The mass fraction of the Al3Ti strengthening phase in the aluminum alloy material is 0.3% to 2%.

[0025] 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:

[0026] The mass percentage of Si element in the aluminum alloy material is 8% to 11%;

[0027] The mass percentage of Ti element in the aluminum alloy material is 0.25% to 0.4%;

[0028] The mass fraction of the Al3Ti strengthening phase in the aluminum alloy material is 0.3% to 1%, and can be optionally 0.35% to 0.6%.

[0029] Adjusting the Si content can adjust the morphology of the Al-Si eutectic structure, while adjusting the Ti content can control the content of the Al3Ti strengthening phase. Adjusting one or more of these content parameters can adjust the mechanical properties of the aluminum alloy. Within the aforementioned range, it is advantageous to maintain good mechanical strength while reducing the Cu content.

[0030] Based on any appropriate embodiment of the present application, further, in some embodiments, the aluminum alloy material includes or does not include a Mg2Si phase, and the mass fraction of the Mg2Si phase in the aluminum alloy material is ≤0.05%, and can be optionally 0%.

[0031] 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:

[0032] The mass percentage of Mg element in the aluminum alloy material is 0.3% to 0.6%;

[0033] The mass percentage of Zn element in the aluminum alloy material is 0.3% to 0.6%;

[0034] The mass ratio of Mg element to Zn element in the aluminum alloy material is 1:(1.1-1.3).

[0035] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material satisfies one or both of the following characteristics:

[0036] The mass percentage of Mg element in the aluminum alloy material is 0.3% to 0.5%;

[0037] The mass percentage of Zn element in the aluminum alloy material is 0.4% to 0.6%;

[0038] The mass ratio of the Mg element to the Zn element in the aluminum alloy material is 1:(1.1-1.25).

[0039] The introduction of Mg element may also produce Al5Cu2Mg8Si 16 Phase, which can play a high-temperature strengthening role. The Mg2Si phase can also play a strengthening role on aluminum alloys, but the Mg2Si phase is a strong cathode phase, which easily accelerates the corrosion of the matrix, resulting in damage to the corrosion resistance of the aluminum alloy material. In the aluminum alloy material system provided in the present application, the Mg2Si phase usually begins to precipitate when the Mg content exceeds about 1.2wt%. By regulating the Mg content, the precipitation behavior of the Mg2Si phase can be regulated so that the Mg2Si phase that appears in the intermediate process is dissolved, so that it does not exist or has a very low content in the finally formed aluminum alloy material, which is beneficial to exert the strengthening effect of Mg while reducing the adverse effects on corrosion performance.

[0040] By adjusting the Zn content, the solid solution strengthening and precipitation strengthening effects of Zn on aluminum alloy materials can be adjusted.

[0041] By controlling the mass ratio of Mg and Zn elements within the aforementioned range, a synergistic strengthening effect can be exerted.

[0042] By controlling at least one of the Mg content and the Zn content within the aforementioned range, it is more conducive to the aluminum alloy material to obtain good mechanical properties and excellent corrosion resistance.

[0043] Based on any appropriate embodiment of the present application, further, in some embodiments, the unavoidable impurity elements include Fe.

[0044] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material satisfies one or both of the following characteristics:

[0045] The mass percentage of the Mn element in the aluminum alloy material is 0.7% to 1.1%, and can be optionally 0.8% to 1.1%;

[0046] 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 is ≤0.2%, optionally ≤0.1%; optionally, the aluminum alloy material includes the AlSiMnFe phase.

[0047] During the casting process of aluminum alloy, Fe impurities are often unavoidable in the formed aluminum alloy, and the Fe impurities can form needle-shaped AlSiMnFe phases.

[0048] The addition of Mn element can play a reinforcing role, mainly by solid solution in the matrix Al and improving the strength of the matrix Al through lattice distortion. In addition, the generated AlSiMnFe phase also has a certain strengthening effect.

[0049] Due to the large contact area between the AlSiMnFe phase and the α-Al matrix and the large potential difference, local galvanic corrosion may occur.

[0050] A small amount of Fe (e.g., Fe content ≤ 0.7 wt%) helps with mold release during casting. However, higher Fe content can reduce the corrosion resistance of the aluminum alloy. By keeping the Fe content within a low range, the adverse effects of Fe on corrosion resistance can be reduced.

[0051] 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 beneficial to reduce the damage of the needle-like AlSiMnFe phase to the corrosion resistance.

[0052] By adjusting the content of Mn, the content of needle-shaped AlSiMnFe phase can be controlled. By adjusting the content of AlSiMnFe phase, the comprehensive performance of corrosion resistance and mechanical properties of aluminum alloy materials can be improved.

[0053] Based on any appropriate embodiment of the present application, further, in some embodiments, the mass proportion of the Sr element in the aluminum alloy material is 200ppm to 500ppm.

[0054] By adjusting the Sr content, the modification effect of Sr on the alloy phase can be adjusted. By controlling the Sr content within a more appropriate range, it is more conducive to optimizing the mechanical properties of aluminum alloy materials.

[0055] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material includes the following constituent elements, by mass percentage: 6% to 11% Si, 0.5% to 0.9% Cu, 0.1% to 0.4% Ti, 0.3% to 0.6% Mg, 0.3% to 0.6% Zn, 0.5% to 1.1% Mn, 0.01% to 0.05% Sr, the unavoidable impurity elements and the balance matrix element Al.

[0056] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material includes the following constituent elements, by mass percentage: 6.5% to 11% Si, 0.5% to 0.8% Cu, 0.2% to 0.4% Ti, 0.3% to 0.6% Mg, 0.3% to 0.6% Zn, 0.7% to 1.1% Mn, 0.02% to 0.05% Sr, the unavoidable impurity elements and the balance matrix element Al.

[0057] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material includes the following constituent elements, by mass percentage: 8% to 11% Si, 0.6% to 0.8% Cu, 0.25% to 0.4% Ti, 0.3% to 0.5% Mg, 0.4% to 0.6% Zn, 0.8% to 1.1% Mn, 0.03% to 0.05% Sr, the unavoidable impurity elements and the balance of matrix element Al.

[0058] By adjusting the types and contents of various elements in aluminum alloy materials, it is more conducive to the aluminum alloy materials to obtain good mechanical properties and excellent corrosion resistance.

[0059] In a second aspect of the present application, an aluminum alloy structural part is provided, which is a formed body of the aluminum alloy material described in the first aspect of the present application.

[0060] In a third aspect of the present application, a method for preparing an aluminum alloy structural part is provided, comprising the following steps:

[0061] heating and melting an aluminum ingot, adding 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 a master alloy, performing melting and refining and slagging to prepare an aluminum alloy refined melt;

[0062] Casting the aluminum alloy melt to obtain an aluminum alloy ingot;

[0063] The aluminum alloy ingot is heat treated and cooled to obtain the aluminum alloy structural part.

[0064] The aluminum alloy structural part as the 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, can be used as an aluminum alloy structural part in a battery case, and can effectively extend the service life of the battery case. The aluminum alloy structural part can be made by using aluminum ingots to provide matrix elements, supplemented by corresponding alloying elements, and undergoing smelting and slagging, casting, heat treatment and cooling to obtain the aluminum alloy structural part. The shape and size of the aluminum alloy structural part can be controlled by selecting a mold of corresponding shape and size in the casting step. It can be understood that the shape and size of the cooled structural part can also be adjusted to obtain an aluminum alloy structural part of the target shape and size. For example, treatment methods including but not limited to sandblasting and grinding can be used.

[0065] In a fourth aspect of the present application, a battery case is provided, wherein the battery case satisfies at least one of the following characteristics:

[0066] At least a portion of the structural members in the battery case comprises the aluminum alloy material described in the first aspect of the present application;

[0067] The battery box includes the aluminum alloy structural member described in the second aspect of the present application; and

[0068] The battery case includes an aluminum alloy structural part prepared by the method for preparing an aluminum alloy structural part described in the third aspect of the present application.

[0069] The battery case provides protection for the battery cells inside. On the one hand, the battery case needs to have good mechanical strength to reduce the damage to the battery cells when they are hit. On the other hand, the battery case is susceptible to galvanic corrosion during storage and battery cycling. Therefore, the battery case also needs to have a certain degree of corrosion resistance. The battery case made of the aforementioned aluminum alloy material or aluminum alloy structural parts can meet the requirements of both mechanical properties and corrosion resistance.

[0070] In a fifth aspect of the present application, a battery system is provided, which includes the battery case described in the fourth aspect of the present application and a battery cell located inside the battery case.

[0071] Based on any suitable embodiment of the present application, further, in some embodiments, the battery cell includes a liquid electrolyte.

[0072] 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 part described in the second aspect of the present application, the aluminum alloy structural part obtained by the preparation method of the aluminum alloy structural part described in the third aspect of the present application, the battery case described in the fourth aspect of the present application, and the battery system described in the fifth aspect of the present application.

[0073] By using the aforementioned aluminum alloy materials, the aforementioned aluminum alloy structural parts, or the battery case including the aforementioned aluminum alloy materials or aluminum alloy structural parts in one or more of the battery system and the electrical device, it is beneficial to improve the reliability and life of the battery system and the electrical device. It can not only reduce the degree of damage to the battery when it is hit, but also improve the corrosion resistance of the battery case, including but not limited to improving the resistance to galvanic corrosion.

[0074] When the battery cells in the battery system include liquid electrolytes, higher corrosion resistance is required for the battery case. The battery system and electrical device provided above are more likely to meet storage and usage requirements.

[0075] In the seventh aspect of the present application, there is provided the use of the aluminum alloy material described in the first aspect of the present application in the preparation of at least one of aluminum alloy structural parts, battery boxes, battery systems and electrical devices.

[0076] The details of one or more embodiments and examples of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In order to better describe and illustrate the embodiments, examples or examples provided in this application, reference may be made to one or more drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of the disclosed application, the currently described embodiments, examples or examples, and any of the currently understood best modes of these applications. Moreover, the same figure numbers are used to represent the same components in all the drawings. It should also be noted that the drawings are drawn in a simplified form and are only used to assist in the explanation of this application for convenience and clarity. The various dimensions of each component shown in the drawings are arbitrarily shown and may be accurate or not drawn to scale. For example, in order to make the illustration clearer, the dimensions of the components are appropriately exaggerated in some places in the drawings. Unless otherwise specified, the components in the drawings are not drawn to scale. This application does not limit every dimension of every component.

[0078] In the attached figure:

[0079] FIG1 is a metallographic structure diagram of an aluminum alloy material in one embodiment of the present application.

[0080] FIG2 is an X-ray diffraction (XRD) pattern of an aluminum alloy material in one embodiment of the present application.

[0081] FIG3 shows the microstructure and element distribution of the aluminum alloy material in one embodiment of the present application.

[0082] FIG4 is a SEM-EDS image of an 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 scanning image, identifying three scanned points.

[0083] Figure 5 is a curve showing the changes in mass fraction, elastic modulus, thermal conductivity and density of the aluminum alloy material with temperature in one embodiment of the present application, wherein 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.

[0084] FIG6 is an AC impedance test result of an aluminum alloy material in one embodiment of the present application.

[0085] FIG7 is an equivalent circuit diagram of the AC impedance test of the aluminum alloy material in FIG5 .

[0086] FIG8 is a potentiodynamic polarization curve of an aluminum alloy material in one embodiment of the present application, wherein the horizontal axis is the chemical potential (unit is V) and the vertical axis is the current density (A / cm 2 ).

[0087] FIG9 is a surface macroscopic morphology diagram of an aluminum alloy material at different corrosion times in a salt spray corrosion test in one embodiment of the present application.

[0088] FIG10 is a schematic diagram of sample dimensions for a tensile test of an aluminum alloy material in one embodiment of the present application.

[0089] FIG11 is a schematic diagram of a battery module according to an embodiment of the present application.

[0090] FIG12 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0091] FIG13 is an exploded view of the battery pack shown in FIG12 according to an embodiment of the present application.

[0092] FIG14 is a schematic diagram of an electrical device according to an embodiment of the present application.

[0093] Explanation of the reference numerals: 1 is a battery pack; 2 is an upper case; 3 is a lower case; 4 is a battery module; 5 is a battery cell; 6 is an electrical device. DETAILED DESCRIPTION

[0094] Below, some embodiments and examples of the aluminum alloy materials, aluminum alloy structural parts and preparation methods thereof, battery cases, battery systems, electrical devices and applications of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same 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 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 described in the claims.

[0095] " scope " disclosed in the present application can be limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and any end value can be included or not included independently, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3,4 and 5 are also listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is merely an abbreviation for a combination of these values. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a parameter is expressed as an integer selected from "2-10", this is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0096] In this application, references to "plurality," "multiple," "multiple," "several," and the like, unless otherwise specified, refer to a quantity greater than or equal to two. For example, "one or more" refers to one or greater than or equal to two. It is understood that references to "any number" of items refer to any suitable combination of multiple items, i.e., any combination of "any number" of items that is consistent with the present application and that allows for the implementation of the present application.

[0097] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0098] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of such phrases in various locations in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive with other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments. References to "implementations" herein have a similar understanding.

[0099] Those skilled in the art will appreciate that, in the methods of each embodiment or embodiment, the order in which each step is written does not mean a strict order of execution and constitutes any limitation to the implementation process, and the detailed order of execution of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present application can be performed in sequence, or can be performed randomly, or can preferably be performed in sequence. For example, method M includes steps (a) and (b), indicating that method M may include steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For another example, method M may also include step (c), indicating that step (c) can be added to method M in any order, for example, method M may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0100] In this application, in open technical features or technical solutions described with words such as "contain," "include," and "include," unless otherwise specified, additional members other than the listed members are not excluded, and it can be regarded as providing both closed features or solutions consisting of the listed members and open features or solutions including additional members in addition to the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or not. It can be regarded as providing both the feature or solution of "A consists of a1, a2, and a3" or "A is selected from a1, a2, and a3", and the feature or solution of "A includes not only a1, a2, and a3, but also other members."

[0101] In this application, unless otherwise specified, 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.

[0102] In this application, "optionally," "optional," and "optional" mean optional, that is, they refer to either option selected from the two parallel options of "yes" or "no." If multiple "options" appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" is independent. Unless otherwise specified, the descriptions "optionally include," "optionally include," etc. in this application, using "optionally include" as an example, mean "may include or not include."

[0103] In this application, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more relevant listed items, and also include any and all combinations of the relevant listed items. "Any and all combinations" include any combination of any two relevant listed items, any more relevant listed items, or all relevant listed items. For example, "A and / or B" means the group consisting 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 A and B", and can also mean "including A, including B, or including A and B", which can be appropriately understood according to the sentence in which it is used.

[0104] As used herein, "combination thereof", "any combination thereof", "any combination thereof" and the like include all suitable combinations of any two or more of the listed items.

[0105] Herein, the “suitable” involved in “suitable combination”, “suitable method”, “any suitable method”, etc. shall be based on the technical solution that can implement this application.

[0106] Herein, the terms "preferred," "better," "more preferable," "suitable," "comparatively better," and "preferable" are used solely to describe preferred implementations or examples and should not be construed as limiting the scope of protection of this application. If multiple "preferred" terms appear in a technical solution, each "preferred" term is considered independent unless otherwise specified and there are no contradictions or mutual constraints.

[0107] In this application, "further", "further", "particularly", "for example", "such as", "example", "for example", etc. are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0108] In this application, the terms "first," "second," "third," "fourth," etc. in "the first aspect," "the second aspect," "the third aspect," "the fourth aspect," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor should they be understood as implicitly indicating the importance or quantity of the indicated technical features. Furthermore, "first," "second," "third," "fourth," etc. serve only as non-exhaustive enumeration and description, and should be understood not to constitute a closed-ended limitation on quantity.

[0109] In this application, the term "room temperature" generally refers to 4°C to 35°C, and may refer to 20°C ± 5°C. In some embodiments of this application, room temperature refers to 20°C to 30°C.

[0110] In this application, when referring to a data range, if the unit is followed only by the right endpoint, it means that the units of the left and right endpoints are the same. For example, "3~5h" or "3-5h" both mean that the units of the left endpoint "3" and the right endpoint "5" are both hours, and both have the same meaning as "3h~5h". Similarly, descriptions involving other parameters such as temperature and size are to be understood in the same manner.

[0111] The weight of the relevant components mentioned in the embodiments or examples of the present application can not only refer to the content of each component, but also represent the proportional relationship of the weights between the components. Therefore, as long as the content of the relevant components in the embodiments or examples of the present application is proportionally enlarged or reduced, it is within the scope described in the present application. Further, the weight involved in the embodiments or examples of the present application can be mass units known in the chemical industry such as μg, mg, g, and kg. Unless otherwise specified, 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 of the two is numerically equal to the corresponding weight ratio W1 / W2.

[0112] In this application, unless otherwise specified, wt% represents weight percentage by weight, which is numerically equivalent to the corresponding mass percentage by mass. In this application, wt% may also be expressed as wt.%.

[0113] In this application, unless otherwise specified, the unit of percentage (%) involved in "mass percentage" and "mass fraction" may also be expressed as wt% or % (w / w).

[0114] In this application, "greater than or equal to" and "greater 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, unless otherwise specified, "greater than or equal to" and "≥" can be regarded as providing two solutions of "greater than" and "equal to". In this application, unless otherwise specified, "less than or equal to" and "≤" can be regarded as providing two solutions of "less than" and "equal to".

[0115] In this application, exemplary descriptions such as "in some embodiments (or examples)" and "in one embodiment (or example)" may include but are not limited to the following meanings: these solutions can be combined with other solutions in a suitable manner to form new technical solutions.

[0116] The battery case, which protects the battery cells, not only requires good mechanical properties to reduce damage to the batteries during impact, but also requires corrosion resistance to extend the battery life. Current aluminum alloys, such as A380 aluminum alloy, need to have their corrosion resistance further improved.

[0117] According to various embodiments and examples of the present application, in the first aspect, the present application provides an aluminum alloy material having a matrix element Al and a relatively low content of Cu, such as 0.5wt% to 0.9wt% of Cu. The aluminum alloy material has good mechanical properties and excellent corrosion resistance, and can be used as the main material of a battery case, which is beneficial to improving the service life of the battery case.

[0118] In this application, unless otherwise specified, "aluminum alloy material is used as the main material of the battery case" means that the aluminum alloy material is used as the main material of at least a part of the structure of the battery case, and the mass proportion of the aluminum alloy material in this part of the structure can exceed 80%, further exceed 90%, and further approach 100% or be 100%. In this application, unless otherwise specified, when "aluminum alloy material is used as the main material of a structural part or product", it is allowed to add other functional components to the aluminum alloy material to further improve the material performance 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 case. At this time, the chemical composition of at least a part of the structure or structural part of the battery case is consistent with the aluminum alloy material, and the mass proportion of the aluminum alloy material in the corresponding structure or corresponding structural part is 100%.

[0119] In this application, unless otherwise specified, "the content of a certain element" refers to the mass percentage of that element in the aluminum alloy material provided herein. For example, "the content of Cu" refers to the mass percentage of Cu in the aluminum alloy material. Unless otherwise specified, "the content of a certain alloy phase" refers to the mass percentage of that alloy phase in the aluminum alloy material provided herein.

[0120] 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 the aluminum alloy material does not contain Al2Cu phase or the content is small, for example, the mass fraction of Al2Cu phase in the aluminum alloy material is ≤1.3%.

[0121] In some embodiments, the present application provides an aluminum alloy material, which includes the following constituent elements, by mass percentage: 6% to 11% Si, 0.5% to 0.9% Cu, 0.1% to 0.4% Ti, 0.2% to 0.6% Mg, 0.25% to 0.6% Zn, 0.5% to 1.1% Mn, 0.01% to 0.05% Sr, matrix element Al, and unavoidable impurity elements;

[0122] The aluminum alloy material may include or exclude the Al2Cu phase. Furthermore, the mass fraction of the Al2Cu phase in the aluminum alloy material may satisfy ≤1.3%.

[0123] In this application, unless otherwise specified, "matrix element" refers to the element that provides the matrix phase. When casting an alloy, an ingot of the matrix element is often used as the starting material, to which modifying elements are added, ultimately forming an alloy phase comprising multiple elements. In this application, the matrix element of the aluminum alloy material is Al.

[0124] In this application, unless otherwise specified, “inevitable impurities” refer to impurity elements that are not intentionally introduced but are inevitably brought into the preparation process.

[0125] In this application, the elemental composition, alloy phase, and alloy structure of aluminum alloy materials may be characterized and analyzed using methods including, but not limited to, X-ray diffraction (XRD), energy dispersive spectrometer (EDS), scanning electron microscopy (SEM), and metallographic microscopy. The operation of these instruments and the data analysis methods are well known to those skilled in the art. Unless otherwise specified, the detection and analysis methods described in the Examples below may be used, but are not limited thereto.

[0126] The aluminum alloy material uses aluminum (Al) as a matrix element and includes silicon (Si), copper (Cu), titanium (Ti), magnesium (Mg), zinc (Zn), manganese (Mn) and strontium (Sr). The composition of the aluminum alloy material is controlled within the aforementioned content range. The matrix element Al in the aluminum alloy material forms an α-Al matrix phase, which is mainly distributed in a morphology close to an equiaxed crystal. 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-like or needle-like Al2Cu phase, which 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 impurity phase morphology and thereby reduce the damage of the impurity phase to the mechanical properties, a high content of Cu element can easily lead to a decrease in the corrosion resistance of the aluminum alloy material and also reduce the elongation of the aluminum alloy material. The potential of the Al2Cu 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 a cathode phase, and locally form an electrochemical microbattery with the nearby Cu-rich matrix phase and Al2Cu phase, so that the matrix phase part of the Cu-poor solid solution is continuously corroded. The content of Al2Cu is basically linearly related to the Cu content. By designing a relatively low copper content, the proportion of the Al2Cu 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 element, it is possible to produce a strengthening effect while having no adverse effect or a small effect on the corrosion resistance. By introducing the Ti element, a circular or nearly elliptical precipitate phase can be formed. The precipitate phase can serve as a non-spontaneous nucleation site during crystallization, has a certain grain refining effect, and can play a strengthening role and improve the elongation. The introduction of Mg and Zn elements can improve the strength of the aluminum alloy material by forming a solid solution and precipitation strengthening. The Sr element is soluble in the matrix phase and can alter the solidification process during casting, modifying the alloy phase of the aluminum alloy material. It can modify the Al-Si eutectic structure into fine fibers, thereby improving mechanical strength. The Mn element can complement the strengthening effect of the Mg element and make the precipitate phase uniformly distributed. In addition, the introduction of the Mn element facilitates the demolding process of casting and can combine with impurity elements to reduce the damage caused by 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 unique microstructure. The multiple synergistic effects between the various elements can effectively improve the corrosion resistance of the aluminum alloy material while also giving the aluminum alloy material good mechanical properties, with both mechanical strength and ductility improved.By reasonably setting the content of elements such as Cu, Mg, and Zn, the foundation can be laid for aluminum alloy materials to have good mechanical properties such as tensile strength and hardness; and by controlling the content of Cu, Ti, and Sr in aluminum alloy materials, the corrosion resistance of aluminum alloy materials can be significantly improved.

[0127] In some embodiments, the mass percentage of Cu in the aluminum alloy material may be 0.5% to 0.9%, optionally 0.5% to 0.8%, and further optionally 0.6% to 0.8%. The mass percentage of Cu in the aluminum alloy material may also be any of the following percentages, or a range consisting 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.

[0128] In some embodiments, the aluminum alloy material may include or exclude the Al2Cu phase. Without limitation, the mass fraction of the Al2Cu phase in the aluminum alloy material may satisfy ≤1.3%, optionally 0.1% to 1.3%, and further optionally 0.8% to 1.3%. The mass fraction of the Al2Cu phase in the aluminum alloy material may also be any of the following percentages, or an interval consisting 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. The mass fraction of the Al2Cu phase in the aluminum alloy material can also be selected from any appropriate range in the following ranges: 0.4% to 1.3%, 0.4% to 1.0%, 0.5% to 1.3%, 0.5% to 1.0%, 0.6% to 1.3%, 0.6% to 1.0%, 0.8% to 1.0%, 0.8% to 1.29%, 0.85% to 1.3%, 0.85% to 1.29%, etc.

[0129] Based on any appropriate 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 appropriate numerical value or range in the context):

[0130] The mass percentage of Cu element in the aluminum alloy material is 0.5% to 0.9%, optionally 0.5% to 0.8%, and further optionally 0.6% to 0.8% (can also be selected from any appropriate content or range in the context);

[0131] The aluminum alloy material includes or does not include an Al2Cu phase. Optionally, the mass fraction of the Al2Cu phase in the aluminum alloy material is ≤1.3%; further optionally, the aluminum alloy material includes an Al2Cu phase, and the mass fraction of the Al2Cu phase in the aluminum alloy material is 0.1% to 1.3%, and further optionally 0.8% to 1.3% (it can also be selected from any suitable content or range in the context).

[0132] The Al2Cu phase content can be controlled by adjusting the mass percentage of Cu in the aluminum alloy. Controlling the Al2Cu phase content within the aforementioned range is more conducive to achieving good mechanical properties and excellent corrosion resistance in the aluminum alloy. Furthermore, it is more conducive to achieving excellent corrosion resistance while also providing the aluminum alloy with good mechanical strength and ductility.

[0133] Based on any appropriate embodiment of the present application, further, in some embodiments, the aluminum alloy material includes a fibrous Al-Si eutectic structure.

[0134] Based on any appropriate embodiment of the present application, further, in some embodiments, the aluminum alloy material includes an Al3Ti strengthening phase.

[0135] Based on any appropriate 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 an Al3Ti strengthening phase.

[0136] In aluminum alloys, the α-Al matrix and Si phase form an Al-Si eutectic phase. This eutectic phase is primarily distributed as fine fibrous structures between the α-Al grains, which helps improve the mechanical strength of the matrix phase. Ti can form round or nearly elliptical Al3Ti precipitates, which serve as non-spontaneous nucleation sites during crystallization, exerting a certain grain-refining effect and contributing to strengthening. Furthermore, improved distribution of the secondary phase and grain refinement strengthen the alloy, which in turn contribute to improved ductility.

[0137] In some embodiments, the mass percentage of Si in the aluminum alloy material is 6% to 11%, optionally 6.5% to 11%, and further optionally 8% to 11%. The mass percentage of Si in the aluminum alloy material can also be any of the following percentages, or an interval consisting 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 appropriate range within the following ranges: 6.5% to 10.5%, 8.5% to 10.5%, etc.

[0138] Regarding the Si content, the eutectic point of Al-Si alloy is 12.5wt%. When the eutectic point is exceeded, primary silicon will be produced first, which is detrimental to corrosion resistance. The present application can adjust the morphology of the Al-Si eutectic structure by adjusting the Si content.

[0139] In some embodiments, the mass percentage of the Ti element in the aluminum alloy material is 0.1% to 0.4%, optionally 0.2% to 0.4%, and further optionally 0.25% to 0.4%. The mass percentage of the Ti element in the aluminum alloy material can also be any of the following percentages, or an interval consisting 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 the Ti element in the aluminum alloy material can also be selected from any suitable range of the following ranges: 0.25% to 0.35%, 0.2% to 0.3%, 0.1% to 0.3%, 0.3% to 0.4%, etc.

[0140] In some embodiments, the mass fraction of the Al3Ti strengthening phase in the aluminum alloy material can be optionally 0.3% to 2%, optionally 0.3% to 1%, and further optionally 0.35% to 0.6%. The mass fraction of the Al3Ti strengthening phase in the aluminum alloy material can also be any of the following percentages, or an interval consisting 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. The mass fraction of the Al3Ti strengthening phase in the aluminum alloy can also be selected from any suitable range within the following ranges: 0.5% to 2%, approximately 0.5%, etc. The term "approximately" here indicates a reasonable range of fluctuation. For example, approximately 0.5% can be ±0.05%, ±0.06%, ±0.08%, ±0.01%, ±0.15%, etc. The Al content can be adjusted to produce the Al3Ti strengthening phase while also controlling the Al3Ti strengthening phase within a smaller range. For example, the mass fraction of the Al3Ti strengthening phase in the aluminum alloy can be controlled to approximately 0.5%. Reducing the precipitation phase is beneficial to improving ductility.

[0141] 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 numerical value or range in the context):

[0142] The mass percentage of Si element in the aluminum alloy material is 6% to 11%, optionally 6.5% to 11%, and further optionally 8% to 11% (can also be selected from any appropriate content or range in the context);

[0143] The mass percentage of Ti element in the aluminum alloy material is 0.1% to 0.4%, optionally 0.2% to 0.4%, and further optionally 0.25% to 0.4% (can also be selected from any appropriate content or range in the context);

[0144] The mass fraction of the Al3Ti strengthening phase in the aluminum alloy material is 0.3% to 2%, optionally 0.3% to 1%, and further optionally 0.35% to 0.6% (can also be selected from any appropriate content or range in the context).

[0145] Adjusting the Ti content can control the Al3Ti strengthening phase content. Adjusting one or more of these content parameters can adjust the mechanical properties of the aluminum alloy. Within the aforementioned range, it is beneficial to maintain good mechanical strength while reducing the Cu content.

[0146] Based on any suitable embodiment of the present application, further, in some embodiments, the aluminum alloy material may include or exclude the Mg2Si phase. In a non-limiting manner, the mass fraction of the Mg2Si phase in the aluminum alloy material may satisfy ≤0.05%, and may be optionally 0% (i.e., absent). The mass fraction of the Mg2Si phase in the aluminum alloy material may also be any of the following percentages, or less than or equal to any of the following percentages, or selected from an interval consisting of any two of the following percentages, or selected from an interval consisting of any of the following percentages and 0%: 0.005%, 0.006%, 0.008%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, etc.

[0147] The introduction of Mg element may also produce Al5Cu2Mg8Si 16 Phase, which can play a high-temperature strengthening role. The Mg2Si phase can also play a strengthening role on aluminum alloys, but the Mg2Si phase is a strong cathode phase, which easily accelerates the corrosion of the matrix, resulting in damage to the corrosion resistance of the aluminum alloy material. In the aluminum alloy material system provided in the present application, the Mg2Si phase usually begins to precipitate when the Mg content exceeds about 1.2wt%. By regulating the Mg content, the precipitation behavior of the Mg2Si phase can be regulated so that the Mg2Si phase that appears in the intermediate process is dissolved, so that it does not exist or contains very little in the finally formed aluminum alloy material, which is beneficial to exert the strengthening effect of the Mg element while reducing the adverse effects on corrosion performance.

[0148] In some embodiments, the mass percentage of Mg in the aluminum alloy material is 0.2% to 0.6%, optionally 0.3% to 0.6%, and further optionally 0.3% to 0.5%. The mass percentage of Mg in the aluminum alloy material can also be any of the following percentages, or an interval consisting 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 Mg in the aluminum alloy material can also be selected from any suitable range of the following ranges: 0.35% to 0.5%, 0.3% to 0.45%, 0.35% to 0.45%, 0.4% to 0.5%, 0.4% to 0.6%, 0.3% to 0.4%, etc.

[0149] In some embodiments, the mass percentage of the Zn element in the aluminum alloy material is 0.25% to 0.6%, optionally 0.3% to 0.6%, and further optionally 0.4% to 0.6%. The mass percentage of the Zn element in the aluminum alloy material can also be any of the following percentages, or an interval consisting 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 within the following ranges: 0.45% to 0.6%, 0.4% to 0.55%, 0.3% to 0.5%, 0.4% to 0.5%, etc.

[0150] In some embodiments, the mass ratio of Mg to Zn in the aluminum alloy material is 1:(1.1-1.3), optionally 1:(1.1-1.25). The mass ratio of Mg to Zn in the aluminum alloy material can also be any of the following ratios, or can be selected from an interval consisting 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 Mg to Zn in the aluminum alloy material can also be selected from any suitable range within the following ranges: 1:(1.1-1.2), etc.

[0151] 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 numerical value or range in the context):

[0152] The mass percentage of Mg element in the aluminum alloy material is 0.2% to 0.6%, optionally 0.3% to 0.6%, and further optionally 0.3% to 0.5% (it can also be selected from any appropriate content or range in the context);

[0153] The mass percentage of Zn element in the aluminum alloy material is 0.25% to 0.6%, optionally 0.3% to 0.6%, and further optionally 0.4% to 0.6% (can also be selected from any appropriate content or range in the context);

[0154] The mass ratio of Mg element to Zn element in the aluminum alloy material is 1:(1.1-1.3), and can be optionally 1:(1.1-1.25) (it can also be selected from any appropriate content or range in the context).

[0155] By adjusting the Zn content, the solid solution strengthening and precipitation strengthening effects of Zn on aluminum alloy materials can be adjusted.

[0156] By controlling the mass ratio of Mg and Zn elements within the aforementioned range, a synergistic strengthening effect can be exerted.

[0157] By controlling at least one of the Mg content and the Zn content within the aforementioned range, it is more conducive to the aluminum alloy material to obtain good mechanical properties and excellent corrosion resistance.

[0158] Based on any appropriate embodiment of the present application, further, in some embodiments, the unavoidable impurity elements include Fe.

[0159] In some embodiments, the mass percentage of the Mn element in the aluminum alloy material is 0.5% to 1.1%, optionally 0.7% to 1.1%, and further optionally 0.8% to 1.1%. The mass percentage of the Mn element in the aluminum alloy material can also be any of the following percentages, or a range consisting 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 the Mn element in the aluminum alloy material can also be selected from any appropriate range within the following ranges: 0.6% to 1.0%, 0.8% to 1.0%, etc.

[0160] In some embodiments, the mass fraction of the AlSiMnFe phase in the aluminum alloy material (which can be recorded 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, or can be an interval consisting of any two of the following percentages, or can be less than or equal to any of the following percentages, or can be greater than 0% and less than or equal to any of the following percentages, or can 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 ranges: 0 <f AlSiMnFe ≤0.2%, 0 <f AlSiMnFe ≤0.1%, etc.

[0161] Based on any appropriate 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 appropriate numerical value or range in the context):

[0162] The mass percentage of the Mn element in the aluminum alloy material is 0.5% to 1.1%, optionally 0.7% to 1.1%, and further optionally 0.8% to 1.1% (can also be selected from any appropriate content or range in the context);

[0163] 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 is ≤0.2%, optionally ≤0.1% (can also be selected from any appropriate content or range in the context).

[0164] During the casting process of aluminum alloy, Fe impurities are often unavoidable in the formed aluminum alloy, and the Fe impurities can form needle-shaped AlSiMnFe phases.

[0165] The addition of Mn element can play a reinforcing role, mainly by solid solution in the matrix Al and improving the strength of the matrix Al through lattice distortion. In addition, the generated AlSiMnFe phase also has a certain strengthening effect.

[0166] Due to the large contact area between the AlSiMnFe phase and the α-Al matrix and the large potential difference, local galvanic corrosion may occur.

[0167] A small amount of Fe (e.g., Fe content ≤ 0.7 wt%) helps with mold release during casting. However, higher Fe content can reduce the corrosion resistance of aluminum alloys. By keeping the Fe content within a low range, the adverse effects of Fe on corrosion resistance can be reduced.

[0168] 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 beneficial to reduce the damage of the needle-like AlSiMnFe phase to the corrosion resistance.

[0169] By adjusting the content of Mn, the content of needle-shaped AlSiMnFe phase can be controlled. By adjusting the content of AlSiMnFe phase, the comprehensive performance of corrosion resistance and mechanical properties of aluminum alloy materials can be improved.

[0170] Based on any suitable embodiment of the present application, further, in some embodiments, the mass proportion of the Sr element in the aluminum alloy material is 0.01% to 0.05%, and can be optionally 200ppm to 500ppm. Wherein, 1ppm represents one part per million. 1ppm=0.0001%, 200ppm=0.02%. The mass proportion of Sr in the aluminum alloy material can also be any of the following values, or an interval consisting of any two of the following values: 100ppm, 150ppm, 200ppm, 250ppm, 300ppm, 350ppm, 400ppm, 450ppm, 500ppm, etc. The mass proportion of the Sr element in the aluminum alloy material can also be selected from any suitable range in the following ranges: 300ppm to 500ppm, etc.

[0171] By adjusting the Sr content, the modification effect of Sr on the alloy phase can be adjusted. By controlling the Sr content within a more appropriate range, it is more conducive to optimizing the mechanical properties of aluminum alloy materials.

[0172] Based on any appropriate embodiment of the present application, further, in some embodiments, the aluminum alloy material includes the following constituent elements, by mass percentage: 6% to 11% Si, 0.5% to 0.9% Cu, 0.1% to 0.4% Ti, 0.3% to 0.6% Mg, 0.3% to 0.6% Zn, 0.5% to 1.1% Mn, 0.01% to 0.05% Sr, unavoidable impurity elements and the balance of matrix element Al.

[0173] Based on any appropriate embodiment of the present application, further, in some embodiments, the aluminum alloy material includes the following constituent elements, by mass percentage: 6.5% to 11% Si, 0.5% to 0.8% Cu, 0.2% to 0.4% Ti, 0.3% to 0.6% Mg, 0.3% to 0.6% Zn, 0.7% to 1.1% Mn, 0.02% to 0.05% Sr, unavoidable impurity elements and the remainder of the matrix element Al.

[0174] Based on any appropriate embodiment of the present application, further, in some embodiments, the aluminum alloy material includes the following constituent elements, by mass percentage: 8% to 11% Si, 0.6% to 0.8% Cu, 0.25% to 0.4% Ti, 0.3% to 0.5% Mg, 0.4% to 0.6% Zn, 0.8% to 1.1% Mn, 0.03% to 0.05% Sr, unavoidable impurity elements and the remainder of the matrix element Al.

[0175] By adjusting the types and contents of various elements in aluminum alloy materials, it is more conducive to the aluminum alloy materials to obtain good mechanical properties and excellent corrosion resistance.

[0176] In some embodiments, by rationally designing the element composition and element content, the aluminum alloy material has a microstructure as shown in FIG1 : nearly equiaxed α-Al crystals and fine, fibrous eutectic structures, as well as a small amount of alloy phases such as Al3Ti and AlSiMnFe.

[0177] In yet another aspect of the present application, a method for preparing 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.

[0178] In some embodiments, a method for preparing an aluminum alloy material is provided, comprising the following steps:

[0179] S100 (melting): heating and melting the aluminum ingot, adding ingredients determined according to the nominal composition of the aluminum alloy material in the form of a master alloy, performing melting and refining and slagging to prepare a refined melt;

[0180] S200 (molding): casting the refined melt to obtain an ingot;

[0181] S300 (heat treatment): The ingot is heat treated and cooled to obtain an aluminum alloy material.

[0182] In this application, unless otherwise specified, "nominal composition" refers to the theoretical value or design value of the target composition.

[0183] In step S100, a refined melt is prepared by smelting, and the obtained refined melt is also referred to as an aluminum alloy refined melt.

[0184] In the present application, "melting" has a well-known meaning in the art, which refers to the operation of heating and melting solid metal and performing tempering, and 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 smelt 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 the smelting.

[0185] The alloying elements can be added in the form of a master alloy, but are not limited thereto. Once the nominal composition of the aluminum alloy material is determined, those skilled in the art can select the appropriate addition temperature and timing based on the properties of each alloying element (e.g., melting point) to ensure that the material remains in a molten state throughout the entire process from heating and melting the aluminum ingot to producing the refined melt.

[0186] 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%, calculated as a mass percentage.

[0187] 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 the high melting point Si, Mn, and Cu are completely melted and the temperature is appropriately lowered.

[0188] In some embodiments, the elements are added in the following manner: AlSi 20 、AlCu 50 、AlTi5、Zn、Mg、AlMn 10 、AlSr 10 and Al. The numbers represent the atomic ratios between the elements, and different numbers correspond to different alloy grades. Those skilled in the art will understand the meaning of the corresponding grades.

[0189] In this application, unless otherwise specified, "melt 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.

[0190] Without limitation, melt refining includes refining.

[0191] In this application, "refining" has a 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 composition characteristics of the aluminum alloy material. In a non-limiting manner, the refining purpose can be achieved by adding a refining agent. The refining agent used in this application can be a commonly used refining agent for casting aluminum alloys, such as a high-efficiency refining agent (non-toxic refining agent), a degassing refining agent, etc.

[0192] In this application, "slag skimming" has a well-known meaning in the art and refers to the step of removing slag from the melt during the smelting process. During the smelting and refining process, slag may float on the surface of the melt, which can be removed by skimming. Slag skimming can be performed once or multiple times.

[0193] In step S200, the refined solution obtained by smelting is cast into an ingot, which is also referred to as an aluminum alloy ingot.

[0194] After casting, the resulting ingot acquires a predetermined shape and size. The ingot may have a predetermined shape and size. The predetermined shape and size may be determined based on experimental test samples or actual needs. The shape and size of the ingot can be controlled by the shape and size of the mold used during casting.

[0195] In step S300, the target aluminum alloy material is prepared by heat treating the ingot obtained by casting.

[0196] The heat treatment can be achieved by keeping the ingot at a certain temperature and can be terminated by cooling.

[0197] In the step of heat treating the ingot, the heat treatment can be carried out in an insulation manner, and a suitable insulation temperature (also referred to 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, such as 70% to 80% of the melting point temperature. The larger the ingot, the longer the required heat treatment insulation time is. A longer insulation time helps to improve the annealing effect. The insulation time can be controlled within a certain time range so that while achieving a good annealing effect, overburning and coarse grains are avoided as much as possible. Diligent slagging during the insulation process helps to obtain a well-formed ingot. A suitable insulation time can be selected according to the size of the ingot. Typically, the holding time during heat treatment is at least 0.5 hours, and can be any of the following durations, or a range consisting of any two of the following durations: 1 hour, 2 hours, 3 hours, 5 hours, 6 hours, 8 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, 48 ​​hours, 50 hours, etc. For example, the holding time during heat treatment can be 36 hours to 50 hours, further 36 hours to 48 hours, and even further 36 hours to 45 hours. Taking an ingot with a size of 20 mm × 35 mm × 10 mm as an example, the annealing time can be 1.5 hours to 3 hours, for example, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.

[0198] Those skilled in the art can select appropriate process parameters to effectively reduce or eliminate the intragranular segregation of elements in the aluminum alloy to achieve the purpose of homogenization and realize the purpose of improving the comprehensive performance of the mechanical properties and corrosion resistance of the aluminum alloy material.

[0199] In some embodiments, the ingot is heat treated, and the cooling step includes keeping the ingot warm and cooling it.

[0200] In some embodiments, during the step of holding and cooling the ingot, the holding temperature may be 500°C to 600°C. The holding time may be determined by referring to the above method. In some embodiments, the holding time may be 1 hour to 3 hours, further 1.5 hours to 2.5 hours, 1.5 hours to 2 hours, etc., for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, etc. In other embodiments, the holding time may be 36 hours to 50 hours, further 36 hours to 48 hours, and further 36 hours to 45 hours, for example, 36 hours, 40 hours, 45 hours, 48 ​​hours, etc.

[0201] In some embodiments, the ingot is heat treated, and in the cooling step, the ingot is cooled to 20°C to 30°C.

[0202] Without limitation, the cooling medium may be an inert gas, oil, air cooling, furnace cooling, or the like.

[0203] In some embodiments, a method for preparing an aluminum alloy material is provided.

[0204] In some embodiments, a method for preparing an aluminum alloy material is provided, comprising the following steps:

[0205] S100: heating and melting an aluminum ingot, adding the required amounts of Mn, Si, Cu, Mg, Zn, Ti, and Sr according to the nominal composition of the aluminum alloy material, performing melting and refining and slagging to prepare a refined melt; wherein each element can be added in the form of pure metal or master alloy;

[0206] S200: casting the refined melt to obtain an ingot;

[0207] S300: keeping the ingot warm and cooling it to obtain an aluminum alloy material.

[0208] In some embodiments, the Mn element, the Si element, the Cu element, the Ti element, and the Sr element are added as master alloys, and the Mg element and the Zn element are added as pure metals.

[0209] In some embodiments, step S100 includes step S110 and step S120.

[0210] In some embodiments, step S110 includes: heating and melting an aluminum ingot, adding ingredients including Mn, Si, Cu, Mg, and Zn elements to the melt of the aluminum ingot for smelting to obtain a fourth melt.

[0211] In some embodiments, step S120 includes: skimming the fourth melt, adding a refining agent, and adding ingredients containing Ti and Sr elements for refining to obtain a refined melt.

[0212] It should be noted that the slagging in step S120 can be performed while step S110 is being implemented.

[0213] Adding the Mn element helps with demoulding and can be added earlier. The Si content is relatively high and can be added relatively earlier. The order of adding the Mn element and the Si element is not particularly limited. The Cu element can be added after adding the Mn element and the Si element, or the Mn element, the Cu element, and the Si element can be added in sequence. The Mg element and the Zn element can be added in a pure metal manner. When added in a pure metal manner, since the Mg element and the Zn element are easily burned, the Mg element and the Zn element can be added after the Si element, the Mn element, and the Cu element with higher melting points have been added, and then under appropriate cooling conditions. The Ti element and the Sr element can be added last, and the Sr element can be added after the Ti element has been added. By adding an intermediate alloy including the Ti element (such as AlTi5), an Al3Ti phase can be formed. The Al3Ti alloy phase can inhibit grain growth and play a role in refining the grains. The Sr element can be added last, which is more conducive to the modification effect of the Sr element on the alloy phase.

[0214] In some embodiments, a charge including the following elements is sequentially added to the melt of the 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.

[0215] In some embodiments, a charge containing the following elements is added to the melt of the aluminum ingot in the following order: Mn, then Cu, then Si, a portion of Ti, Zn, and a portion of Sr, then Mg, then the remaining Ti, and then the remaining Sr. Furthermore, the remaining Ti is added first, followed by the remaining Sr.

[0216] In this application, an ingredient containing an X element may be referred to as an "X ingredient." As one example, an ingredient containing a Mn element may be referred to as a Mn ingredient.

[0217] In some embodiments, in the step of heating and melting the aluminum ingot, the heating temperature may be 730° C. to 750° C. Non-limiting examples of the heating temperature include 730° C., 740° C., 750° C., and the like.

[0218] In some embodiments, a method for preparing an aluminum alloy material is provided, comprising the following steps:

[0219] S112: heating the aluminum ingot to 730° C. to 750° C. and maintaining the temperature, adding a material containing the Mn element and smelting the material under the maintaining temperature to obtain a first melt, and adding a material containing the Cu element to the first melt and smelting the material to obtain a second melt;

[0220] S114: Cooling the second melt to 700° C. to 720° C. and maintaining the temperature, adding a material containing Si, a portion containing Ti, a material containing Zn, and a portion containing Sr to the second melt under the maintaining temperature condition, and smelting the material to obtain a third melt, adding a material containing Mg to the third melt at 718° C. to 722° C. and smelting the material to obtain a fourth melt;

[0221] S116: The fourth melt is deslagging, a refining agent is added, and ingredients containing the remaining Ti element (also referred to as the remaining Ti ingredient) and ingredients containing the remaining Sr element (also referred to as the remaining Sr ingredient) are added for refining to obtain a refined melt.

[0222] S200: casting the refined melt to obtain an ingot;

[0223] S300: The ingot is kept at a certain temperature (e.g., 500°C to 600°C) for a suitable time (the suitable holding time is selected according to the size of the ingot, such as 45h to 50h, 1h to 2h, 1.5h to 2.5h, etc.), and cooled (e.g., cooled to 20°C to 30°C) to obtain an aluminum alloy material.

[0224] In some embodiments, a method for preparing an aluminum alloy material is provided, comprising the following steps:

[0225] S112: heating the aluminum ingot to 730° C. to 750° C. and maintaining the temperature, adding a master alloy containing a Mn element and smelting the ingot under the maintaining temperature to obtain a first melt, and adding a master alloy containing a Cu element and smelting the ingot to obtain a second melt;

[0226] S114: Cooling the second melt to 700° C. to 720° C. and maintaining the temperature, adding a master alloy containing Si, a master alloy containing a portion of Ti, and a master alloy containing a portion of Sr to the second melt under the maintaining temperature condition for smelting, adding pure Zn metal for smelting to obtain a third melt, adding pure Mg metal to the third melt for smelting at 718° C. to 722° C. to obtain a fourth melt;

[0227] S130: Deslagging the fourth melt, adding a refining agent, adding a master alloy containing the remaining Ti element and a master alloy containing the remaining Sr element, and refining to obtain a refined melt;

[0228] S200: casting the refined melt to obtain an ingot;

[0229] S300: The ingot is kept at a certain temperature (e.g., 500°C to 600°C) for a suitable time (the suitable holding time is selected according to the size of the ingot, such as holding at 45°C to 50h, or holding at 1h to 2h, 1.5h to 2.5h, etc.), and cooled (e.g., cooled to 20°C to 30°C) to obtain an aluminum alloy material.

[0230] In some embodiments, step S100 includes the above-mentioned steps S112, S114, and S116.

[0231] In a second aspect of the present application, an aluminum alloy structural part is provided, which is a formed body of the aluminum alloy material described in the first aspect of the present application.

[0232] In this application, unless otherwise specified, a "formed body of an aluminum alloy material" refers to a solid object composed of the aluminum alloy material and having a predetermined shape and size. The shape and size of the aluminum alloy material can be defined by a mold during its production, thereby forming a solid object of predetermined shape and size.

[0233] The aluminum alloy structural member formed from the aluminum alloy material described in the first aspect of the present application may have good mechanical properties and excellent corrosion resistance, and can be used as an aluminum alloy structural member in a battery case, which can effectively extend the service life of the battery case.

[0234] In a third aspect of the present application, a method for preparing an aluminum alloy structural part is provided, which can be prepared using the aforementioned method for preparing the aluminum alloy material.

[0235] In some embodiments, a method for preparing an aluminum alloy structural part is provided, comprising the following steps:

[0236] S100 (melting): heating and melting the aluminum ingot, adding ingredients determined according to the nominal composition of the aluminum alloy material in the form of a master alloy, performing melting and refining and slagging to prepare an aluminum alloy refined melt;

[0237] S200 (molding): casting the aluminum alloy refined melt to prepare an aluminum alloy ingot;

[0238] S300 (heat treatment): The aluminum alloy ingot is heat treated and cooled to produce aluminum alloy structural parts.

[0239] In step S100 , the aluminum alloy material may be the aluminum alloy material described in the first aspect of the present application.

[0240] 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, an aluminum alloy structural part can be obtained while obtaining the aluminum alloy material.

[0241] The implementation of step S100, step S200 and step S300 may also refer to the aforementioned method for preparing the aluminum alloy material, and may also refer to the following implementation manner or examples.

[0242] The aluminum alloy structural part can be produced by using aluminum ingots to provide a matrix element, supplemented with corresponding alloying elements, and then undergoing smelting, refining, slagging, casting, heat treatment, and cooling. The shape and size of the aluminum alloy structural part can be controlled by selecting a mold of a corresponding shape and size during the casting step. It is understood that the shape and size of the cooled structural part can also be adjusted to obtain an aluminum alloy structural part of a target shape and size, for example, by using treatments including but not limited to sandblasting and polishing.

[0243] In a fourth aspect of the present application, a battery case is provided, which may meet at least one of the following characteristics:

[0244] At least a portion of the structural members in the battery case comprises the aluminum alloy material described in the first aspect of the present application;

[0245] The battery box includes the aluminum alloy structural member described in the second aspect of the present application; and

[0246] The battery case includes an aluminum alloy structural part prepared by the method for preparing an aluminum alloy structural part described in the third aspect of the present application.

[0247] The battery case provides protection for the battery cells inside. On the one hand, the battery case needs to have good mechanical strength to reduce the damage to the battery cells when they are hit. On the other hand, the battery case is susceptible to galvanic corrosion during storage and battery cycling. Therefore, the battery case also needs to have a certain degree of corrosion resistance. The battery case made of the aforementioned aluminum alloy material or aluminum alloy structural parts can meet the requirements of both mechanical properties and corrosion resistance.

[0248] Without limitation, the portions of the battery case containing the aforementioned aluminum alloy material may include one or more of, but are not limited to, the bottom plate, the panel, and the bracket. The portions of the battery case containing the aforementioned aluminum alloy material may be integrally formed or fixedly connected by suitable means, such as seamless welding, to better match the desired shape and size.

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

[0250] The aforementioned aluminum alloy material can be applied to lithium battery cases, but is not limited thereto.

[0251] In a fifth aspect of the present application, a battery system is provided, which includes the battery case described in the fourth aspect of the present application and a battery cell located inside the described battery case.

[0252] Based on any suitable embodiment of the present application, further, in some embodiments, the battery cell includes a liquid electrolyte.

[0253] 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 part described in the second aspect of the present application, the aluminum alloy structural part obtained by the preparation method of the aluminum alloy structural part described in the third aspect of the present application, the battery case described in the fourth aspect of the present application, and the battery system described in the fifth aspect of the present application.

[0254] In the seventh aspect of the present application, there is provided the use 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 case, a battery system and an electrical device.

[0255] By using the aforementioned aluminum alloy materials, the aforementioned aluminum alloy structural parts, or the battery case including the aforementioned aluminum alloy materials or aluminum alloy structural parts in one or more of the battery system and the electrical device, it is beneficial to improve the reliability and life of the battery system and the electrical device. It can not only reduce the degree of damage to the battery when it is hit, but also improve the corrosion resistance of the battery case, including but not limited to improving the resistance to galvanic corrosion.

[0256] In this application, unless otherwise specified, a "battery cell" refers to a basic unit that can realize the mutual conversion of chemical energy and electrical energy.

[0257] In some embodiments, the battery cell is a fuel cell, the corresponding battery housing is a fuel cell housing, and the corresponding battery system is a fuel cell system.

[0258] In this application, unless otherwise specified, a "fuel cell housing" refers to a housing containing a fuel cell. In this application, unless otherwise specified, "fuel cell" has the commonly known meaning in the art, meaning a chemical device that directly converts the chemical energy of a fuel into electrical energy; and a "fuel cell" refers to a cell that directly converts the chemical energy of a fuel into electrical energy.

[0259] In some embodiments, the battery cells are lithium batteries, the corresponding battery housing is a lithium battery housing, and the corresponding battery system is a lithium battery system. In this case, the active ions in the battery cells include lithium ions. The lithium battery may be a lithium-ion secondary battery.

[0260] In this application, unless otherwise specified, a "lithium battery case" refers to a battery case containing a lithium battery cell. In this application, unless otherwise specified, "lithium battery" has the commonly known meaning in the art, referring to a type of battery whose active ions include lithium ions; and "lithium battery cell" refers to a battery cell whose active ions include lithium ions.

[0261] In some embodiments, the battery cell is a secondary battery, the corresponding battery case is a secondary battery case, and the corresponding battery system is a secondary battery system. In some embodiments, the battery cell may include a positive electrode sheet, a negative electrode sheet, and an electrolyte. During the battery charge and discharge process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role in conducting active ions between the positive electrode sheet and the negative electrode sheet. In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be made into an electrode assembly by a winding process or a lamination process.

[0262] When the battery cells in the battery system include liquid electrolytes, higher corrosion resistance is required for the battery case. The battery system and electrical device provided above are more likely to meet storage and usage requirements.

[0263] The battery case includes at least one battery cell. The battery case may include one or more battery cells. The present application does not specifically limit the shape of the battery cells, which may be cylindrical, square, or any other shape. In some embodiments, the battery cells may include an outer packaging.

[0264] The outer packaging of the battery cell can be used to encapsulate the above-mentioned electrode assembly and electrolyte, but is not limited thereto.

[0265] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the battery cell may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic. Non-limiting examples of plastic include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0266] In some embodiments, the outer packaging may include a housing and a cover. The housing may include a bottom plate and side plates connected to the bottom plate, with the bottom plate and side plates enclosing a receiving cavity. The housing may have an opening communicating with the receiving cavity, and the cover may be positioned over the opening to seal the receiving cavity.

[0267] Without limitation, the aforementioned electrode assembly may be encapsulated in a housing cavity; in some embodiments, a liquid electrolyte may be impregnated in the electrode assembly; the number of electrode assemblies contained in a battery cell may be one or more, and those skilled in the art may select according to actual needs.

[0268] The battery system may be a battery module 4 or a battery pack 1 .

[0269] 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 a suitable number of battery cells according to the application and capacity of the battery module.

[0270] Figure 11 shows an example battery module 4. Referring to Figure 11 , in the battery module 4, multiple battery cells 5 may be arranged sequentially along the length of the battery module 4. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells 5 may be secured by fasteners. In some embodiments, the battery module 4 may further include a housing having a storage space, wherein the multiple battery cells 5 are housed in the storage space.

[0271] In some embodiments, the battery modules 4 may be assembled into a battery pack 1. The battery pack may contain one or more battery modules. Those skilled in the art may select an appropriate number based on the application and capacity of the battery pack.

[0272] In some embodiments, the battery module 4 may include a battery box that provides a receiving space in which the plurality of battery cells 5 are received.

[0273] Figures 12 and 13 illustrate an example battery pack 1. Referring to Figures 11 and 12 , the battery pack 1 may include a battery case and multiple battery modules 4 disposed within the battery case. The battery case comprises an upper case 2 and a lower case 3. The upper case 2 can be positioned over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery case.

[0274] Battery cells can be used as power sources or energy storage units for electrical devices. These devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., 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, and energy storage systems.

[0275] As an electrical device, a battery cell or a battery system can be selected according to its usage requirements.

[0276] Figure 14 shows an example of an electric device 6. This electric device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the electric device's requirements for high power and high energy density of battery cells or battery systems, a battery pack or battery module can be used.

[0277] As another example, an electric device may be a mobile phone, a tablet computer, a laptop computer, etc. Such an electric device is usually required to be lightweight and thin, and may use a battery cell or a battery system as a power source.

[0278] In yet another aspect of the present application, there is provided a use of the aluminum alloy material of the first aspect of the present application in preparing at least one of a battery case, a battery cell, a secondary battery, and an electrical device.

[0279] Below, some embodiments of the present application are described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where the techniques or conditions are not specified in the embodiments, they are carried out according to the description above, or according to the techniques or conditions described in the literature in this area or according to the product specifications. Where the manufacturers of the reagents or instruments used are not specified, they are conventional products that can be obtained commercially, or can be synthesized in a conventional manner through commercially available products. The following examples use the same refining agent.

[0280] In the following examples, room temperature refers to 20°C to 30°C.

[0281] 1. Preparation of aluminum alloy materials

[0282] (1) Preparation method

[0283] Taking the Mn element as an example, the corresponding ingredients of the Mn element (as shown in Table 1) are recorded as "Mn ingredients".

[0284] (1) First, add the pure aluminum ingot into the melting furnace and heat it to 730℃~750℃. After the temperature is kept to melt, add the Mn ingredient. After the Mn ingredient is melted, add the Cu ingredient. After the temperature drops to 700℃~720℃, add the Si ingredient, a part of the Ti ingredient, the Zn ingredient and a part of the Sr ingredient to melt. After the above elements are melted, add the Mg ingredient at about 720℃. After the Mg ingredient is melted, let it stand and slag, add the refining agent, and after slag removal, add the remaining Ti ingredient and the remaining Sr ingredient. Finally, cast the ingot of the preset shape and preset size. The preset shape and preset size are the sample size required for the test.

[0285] (2) The ingot is placed at a temperature of 500°C to 600°C for 1.5 hours to 2 hours, and then cooled to room temperature with water. 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 case, including but not limited to the main material or component material of a lithium battery case, a fuel cell case, etc.

[0286] (II) Examples and Comparative Examples

[0287] Example 1.

[0288] (1) Select alloy composition

[0289] The aluminum alloy material comprises, by mass percentage, the following elements (nominal composition): Si: 8.5%, Cu: 0.7%, Ti: 0.3%, Mg: 0.4%, Zn: 0.5%, Mn: 1.0%, Sr: 0.04%, and the remainder is Al. See Table 1.

[0290] The ingredients of each element are: AlSi 20 (Si ingredients), AlCu 50 (Cu ingredient), AlTi5 (Ti ingredient), Zn (Zn ingredient), Mg (Mg ingredient), AlMn 10 (Mn ingredient), AlSr 10 (Sr ingredients) and Al. Taking 1 kilogram (kg) as an example, the Zn burn-out rate is 12% and the Mg burn-out rate is 15%.

[0291] (2) Alloy smelting

[0292] First, pure aluminum ingots are added to a melting furnace and heated to 740°C. After the temperature is maintained and melted, Mn is added. After the Mn is melted, Cu is added. After the temperature drops to 710°C, Si, Ti, Zn, and Sr are added and melted. After the above elements are melted, Mg is added. After the Mg is melted, it is allowed to stand and slag is skimmed. A refining agent is added. After the slag is skimmed, Ti and Sr are added. Finally, an ingot is cast.

[0293] (3) Heat treatment

[0294] The ingot was kept at 550° C. for 2 h, and then water-cooled to room temperature to obtain an aluminum alloy material.

[0295] Example 2.

[0296] Aluminum alloy ingots and aluminum alloy materials were prepared using a method substantially the same as in Example 1, except that the alloy compositions were different.

[0297] In terms of mass percentage, the constituent elements of the aluminum alloy material are (nominal composition): Cu: 0.7%, Ti: 0.1%, Mg: 0.5%, Zn: 0.3%, Mn: 0.8%, Sr: 0.04%, and the rest is Al.

[0298] Example 3.

[0299] Aluminum alloy ingots and aluminum alloy materials were prepared using a method substantially the same as in Example 1, except that the alloy compositions were different.

[0300] In terms of mass percentage, the constituent elements of the aluminum alloy material are (nominal composition): Cu: 0.7%, Ti: 0.2%, Mg: 0.4%, Zn: 0.5%, Mn: 0.6%, Sr: 0.04%, and the rest is Al.

[0301] Example 4.

[0302] Aluminum alloy ingots and aluminum alloy materials are prepared using a method substantially the same as in Example 1, except that step (2) is different.

[0303] Step (2) in Example 4 is as follows: first, a pure aluminum ingot is added to a smelting furnace and heated to 730°C. After the ingot is melted at this temperature, a Mn ingredient is added. After the Mn ingredient is melted, a Cu ingredient is added. After the temperature drops to 700°C, Si ingredient, Ti ingredient, Zn ingredient, and Sr ingredient are added and melted. After the above elements are melted, a Mg ingredient is added. After the Mg ingredient is melted, the mixture is allowed to stand and slag is skimmed. A refining agent is added. After the slag is skimmed, Ti ingredient and Sr ingredient are added. Finally, an ingot is cast by casting.

[0304] Example 5.

[0305] Aluminum alloy ingots and aluminum alloy materials are prepared using a method substantially the same as in Example 1, except that step (2) is different.

[0306] Step (2) in Example 5 is as follows: first, a pure aluminum ingot is added to a smelting furnace and heated to 750°C. After the ingot is melted, a Mn ingredient is added. After the Mn ingredient is melted, a Cu ingredient is added. After the temperature drops to 720°C, Si ingredient, Ti ingredient, Zn ingredient, and Sr ingredient are added and melted. After the above elements are melted, a Mg ingredient is added. After the Mg ingredient is melted, the slag is skimmed, a refining agent is added, and after the slag is skimmed, Ti ingredient and Sr ingredient are added. Finally, an ingot is cast by casting.

[0307] Example 6.

[0308] Aluminum alloy ingots and aluminum alloy materials are prepared using a method substantially the same as in Example 1, except that step (3) is different.

[0309] Step (3) in Example 6 is as follows: the ingot is allowed to stand and kept at 500° C. for 1.75 h, and then water-cooled to room temperature to obtain an aluminum alloy material.

[0310] Example 7.

[0311] Aluminum alloy ingots and aluminum alloy materials are prepared using a method substantially the same as in Example 1, except that step (3) is different.

[0312] Step (3) in Example 7 is as follows: the ingot is allowed to stand and kept at 600° C. for 2.25 h, and then water-cooled to room temperature to obtain an aluminum alloy material.

[0313] Example 8.

[0314] Aluminum alloy ingots and aluminum alloy materials are prepared using a method substantially the same as in Example 1, except that step (3) is different.

[0315] Step (3) of Example 8 is as follows: the ingot is allowed to stand at 450° C. for 2 h, and then water-cooled to room temperature to obtain an aluminum alloy material.

[0316] Example 9.

[0317] Aluminum alloy ingots and aluminum alloy materials are prepared using a method substantially the same as in Example 1, except that step (3) is different.

[0318] Step (3) of Example 9 is as follows: the ingot is allowed to stand at 550° C. for 1.25 h, and then water-cooled to room temperature to obtain an aluminum alloy material.

[0319] Comparative Example 1.

[0320] Aluminum alloy ingots and aluminum alloy materials were prepared using a method substantially the same as in Example 1, except that the alloy composition used to prepare the aluminum alloy ingots was different.

[0321] In terms of mass percentage, the constituent 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 rest is Al.

[0322] Comparative Example 2.

[0323] Aluminum alloy ingots and aluminum alloy materials are prepared using a method substantially the same as in Example 1, except that step (2) is different.

[0324] Step (2) of Comparative Example 2 is as follows: first, a pure aluminum ingot is added to a smelting furnace and heated to 800°C. After the ingot is melted at this temperature, a Mn ingredient is added. After the Mn ingredient is melted, a Cu ingredient is added. After the temperature drops to 750°C, Si ingredient, Ti ingredient, Zn ingredient, and Sr ingredient are added and melted. After the above elements are melted, a Mg ingredient is added. After the Mg ingredient is melted, the slag is skimmed, a refining agent is added, and after the slag is skimmed, Ti ingredient and Sr ingredient are added. Finally, an ingot is cast by casting.

[0325] Comparative Example 3.

[0326] Aluminum alloy ingots and aluminum alloy materials were prepared using a method substantially the same as in Example 1, except that the alloy composition was substantially consistent with that of A380 aluminum alloy.

[0327] The nominal composition of the aluminum alloy materials in each embodiment and comparative example can be found in Table 1.

[0328] Table 1.

[0329] The chemical composition of the A380 aluminum alloy in Comparative Example 3 can be found in Table 2.

[0330] Table 2. Element composition of A380 aluminum alloy

[0331] In Table 2, “ / ” indicates that the element component is not actively added.

[0332] 2. Test and Analysis Methods

[0333] (1) Actual component analysis

[0334] Inductively coupled plasma optical emission spectrometer (ICP instrument, Avio 5000) was used for elemental analysis to accurately measure the actual composition of the aluminum alloy material.

[0335] (2) Microstructure analysis

[0336] 1. Phase analysis

[0337] X-ray diffraction (XRD) was used to detect the phase with higher content.

[0338] XRD test instrument and parameters: D8 Advance Da Vinci X, Cu Kα1, scanning range (2θ) 20° to 110°, scanning speed 5° / min.

[0339] It should be noted that during XRD phase detection, only phases with a content greater than 5 wt% will have obvious diffraction peaks. Low-content alloy phases with a content of no more than 5% are analyzed by energy dispersive spectrometer (EDS).

[0340] FESEM+EDS instrument and parameters: A FEI NOVA NanoSEM 230 field emission scanning electron microscope (FESEM+EDS) was used. The probe type (det) was ETD, and the accelerating voltage (HV) was 15 kV. Other parameters can be seen in Figure 3, where the magnification (mag) was 1000x, the working distance (WD) was 6.5 mm, the image width (HFW) was 298 μm, and the beam spot diameter (spot) was 5.5 nm. The resulting images are also referred to as SEM-EDS images.

[0341] 2. Metallographic structure analysis

[0342] Instrument and test parameters: CX40M metallographic microscope, magnifications include 25x, 100x, 20x, 200x, 500x and 1000x, and other magnifications can also be selected.

[0343] 3. Analysis method of mass fraction of different alloy phases:

[0344] Jmatpro simulation calculation.

[0345] (3) Mechanical properties testing and corrosion detection

[0346] The aluminum alloy materials prepared in Examples 1 to 9 and Comparative Examples 1 to 3 were subjected to hardness testing, tensile testing, and corrosion testing with reference to GB / T 4340.1-1999 Metal Vickers hardness test Part 1: Test method.

[0347] 1. Hardness test

[0348] Instrument: Hardness tester.

[0349] Test parameters: Loading load 0.1kg.

[0350] 2. Tensile test:

[0351] (1) Sample size, as shown in Figure 10, in millimeters (mm), where R2.5 indicates a radius of 2.5 mm.

[0352] (2) Testing instrument: Z20 universal electronic testing machine.

[0353] (3) Test and analysis methods:

[0354] Aluminum alloy tensile specimens were wrapped with blue film, leaving only the test surface. The test lasted 600 hours, with samples collected every 24 hours for tensile testing. At least three replicates were used for each test.

[0355] Mechanical properties tests were performed on tensile specimens at different corrosion stages to obtain stress-strain curves. These were then analyzed to determine tensile strength (UTS, also known as tensile strength or ultimate tensile strength), elongation (El), and yield strength (YS). A higher elongation indicates better ductility.

[0356] 3. Corrosion test

[0357] (1) Electrochemical corrosion test

[0358] Electrochemical corrosion includes: open circuit voltage test, AC impedance test, and potentiodynamic polarization test.

[0359] Test solution: 3.5 wt% NaCl aqueous solution.

[0360] Before the test, the die-cast aluminum alloy was cut into samples of 10 mm × 10 mm × 2 mm and the samples were cold mounted with epoxy resin to ensure that only 1 cm of the exposed area was 2 The test surface is also ground with sandpaper, then polished with a polishing agent until the sample surface is neat and bright, cleaned with ethanol, and dried for later use.

[0361] During the test, the open circuit voltage (OCP) of the sample was first measured. After the OCP stabilized for 60 minutes, the sample was subjected to an alternating current impedance spectroscopy (EIS) to measure the electrochemical impedance spectroscopy at different AC frequencies. A 10mV AC sine wave was used as the excitation voltage, and the test frequency was controlled within 0.01Hz to 105Hz.

[0362] After the test, the EIS results were fitted with an equivalent circuit to analyze the parameters of each component in the equivalent circuit diagram. Following the AC impedance test, the sample was subjected to potentiodynamic polarization testing. The scan rate was 0.167 mV / s, starting from an OCP potential of -300 mV, until the current exceeded 1 mA. After the test, the polarization characteristics of the sample were fitted with a Tafel fit using ZSimpWin v3.40 software.

[0363] (2) Salt spray corrosion test

[0364] The test was conducted at 35°C using a 3.5 wt% NaCl aqueous solution.

[0365] The macromorphology, micromorphology, corrosion mass loss and corrosion rate of the box material were analyzed every 24 hours for a total test time of 600 hours.

[0366] Before the test, a 15mm×15mm×2mm block of aluminum alloy sample was wrapped with a blue film on the non-test surface. The test surface was ground, polished, and dried before being weighed W0. The total test duration was 600 hours. During the test, a batch of samples was taken every 24 hours for observation of the surface macromorphology and micromorphology. After observation, chromic acid cleaner (20g / L Cr2O3+50mL / L H3PO4) was used to remove corrosion products on the sample surface and the sample was weighed again to calculate the corrosion rate and conduct morphological observation. The test duration of the i-th sampling was recorded as Ti, and the weight at the i-th sampling was recorded as Wi. At least three parallel samples were set for each test.

[0367] (A) Macromorphology testing method

[0368] Samples: The corrosion time points for sampling were as described above.

[0369] Instrument: CX40M metallographic microscope. The above-mentioned test methods can be used.

[0370] (B) Micromorphology testing method

[0371] Samples: The corrosion time points for sampling were as described above.

[0372] Instrument: FEI NOVA NanoSEM 230. The aforementioned test method can be used.

[0373] (C) Corrosion mass loss and corrosion rate analysis methods

[0374] The quality loss of the i-th sampling is W=W0-Wi.

[0375] The corrosion rate Ri at the time of sampling for the i-th time can be substituted into formula (I) to calculate: 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, in mg;

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

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

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

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

[0382] (3) Immersion corrosion test

[0383] A 3.5 wt% NaCl aqueous solution was used.

[0384] Staged immersion corrosion involves analyzing the macromorphology, micromorphology, and corrosion rate of the box material every 10 days for a total test time of 30 days. In the application, 1 day = 1 day.

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

[0386] Before the test, the test surface was ground and polished, then rinsed with deionized water and ethanol in turn. After drying and weighing, the sample was placed in a desiccator for storage and standby use. During the test, the sample was placed in a container and 500 mL of corrosion solution was added. The composition of the corrosion solution is: 3.5 wt% NaCl aqueous solution. After sealing, the entire container was placed in a constant temperature water bath tank with the temperature set to 25°C. Samples were taken every 10 days (i.e., the test time was 10 days, 20 days, and 30 days respectively) to observe the macroscopic and microscopic morphologies of the sample surface after corrosion. Subsequently, the corrosion products on the sample surface were removed, the sample mass before and after corrosion was compared, and the corresponding immersion corrosion rate was calculated. Three parallel samples were set for each test.

[0387] 3. Test Results Analysis

[0388] The experimental group of Example 1 is also recorded as "N1", and the prepared aluminum alloy material is also recorded as N1 alloy.

[0389] 1. Comparison between nominal composition and actual composition

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

[0391] Table 3. Nominal composition and actual composition of aluminum alloy materials in Example 1

[0392] The element contents in Table 3 refer to the mass percentage in the aluminum alloy material, in wt%.

[0393] (2) Phase analysis

[0394] The description is given by taking Example 1 as an example.

[0395] The metallographic structure of the aluminum alloy material prepared in Example 1 can be seen in Figure 1. Among them, the α-Al matrix phase is mainly distributed in a morphology close to equiaxed crystals, and the eutectic Si phase is distributed between the α-Al grains in a fine fibrous structure, and also contains a small amount of other alloy phases. Due to the addition of a small amount of Sr for modification, unlike the Al-Si eutectic structure in the A380 aluminum alloy of Comparative Example 3, the eutectic Si phase in the aluminum alloy material of Example 1 is transformed into a fibrous and granular morphology. Due to the significant reduction in the Cu content in the alloy, the Al2Cu phase similar to that in the A380 alloy was not observed. Due to the low Mg and Zn content, no obvious Mg2Si phase was observed. In addition, some round or elliptical Ti-rich phases (Al3Ti phases), needle-shaped AlSiMnFe phases or multi-branched Mn-rich phases (AlSiMnFeCu phases) were found in the aluminum alloy material of Example 1.

[0396] The XRD pattern of the aluminum alloy material of Example 1 can be found in Figure 2. The diffraction peaks in the figure are primarily due to the α-Al matrix phase and the Si phase. No other alloy phases were detected, indicating that the remaining alloy phases are relatively low in content. According to Figure 1, the ratio of the Si phase to the α-Al matrix phase is approximately 1:(8-9).

[0397] 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 found in the SEM-EDS image of Figure 4. The Ti element is distributed in a circular or elliptical shape in the SEM image, which is a circular or elliptical alloy phase observed in the metallographic structure, with a composition of Al3Ti, and is a strengthening phase; the Si element is distributed in a fibrous or granular shape 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 needle-shaped and multi-branched alloy phases, please refer to Figure 4 and Table 4. The needle-shaped 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 needle-shaped AlSiMnFe phase larger and some slender branches appear.

[0398] Table 4. EDS chemical composition of the aluminum alloy material of Example 1 in Figure 4

[0399] “-” in Table 4 indicates that the sample was not detected.

[0400] Through simulation calculation, the mass fractions of the several different alloy phases in each embodiment are respectively in accordance with:

[0401] (1) The mass fraction of the Al2Cu phase in the aluminum alloy material is ≤1.3, and also satisfies 0.1% to 1.3%; among them, Example 1 also satisfies 0.8% to 1.3%.

[0402] (2) The mass fraction of the Al3Ti strengthening phase in the aluminum alloy material satisfies 0.3% to 2%, and also satisfies 0.3% to 1%. In Example 1, it also satisfies 0.35% to 0.6%.

[0403] (3) The mass fraction of the AlSiMnFe phase in the aluminum alloy material satisfies ≤0.2% and also satisfies ≤0.1%.

[0404] (4) The mass fraction of the Mg2Si phase in the aluminum alloy material satisfies ≤0.05% and cannot be detected, which can be basically regarded as 0%.

[0405] (3) Mechanical properties testing and corrosion detection

[0406] According to the test results of mechanical properties test and corrosion detection, each of Examples 1-9 has good mechanical properties and excellent corrosion resistance, which is significantly better than Comparative Examples 1-3.

[0407] The test analysis results of each embodiment are described using embodiment 1 as an example.

[0408] Figure 5 shows the mass fraction, elastic modulus, thermal conductivity, and density of the A380 aluminum alloy and the aluminum alloy material (N1 alloy) in Example 1 as a function of temperature, obtained through Jmatpro analysis. 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 the N1 alloy is similar to that of the A380 alloy, ranging from 480°C to 630°C. The elastic modulus of the N1 alloy is slightly higher than that of the A380 alloy, at 75.37 GPa at room temperature. The thermal conductivity of the N2 alloy is higher than that of the A380 alloy, at 160.94 W / m·K at room temperature. The density of the N1 alloy is lower than that of the A380 alloy, at 2.71 g / cm 3 .

[0409] The results of the AC impedance test of the aluminum alloy material of Example 1 (also denoted as N1) can be found in Figure 6. Compared with the A380 alloy (Comparative Example 3), the aluminum alloy material of Example 1 exhibits higher impedance and phase angle, whether at low frequency or high frequency, as shown in (a) and (b) in Figure 6). Although the impedance of the A380 alloy gradually approaches that of the aluminum alloy material of Example 1 at low frequency, it is still less than its impedance. In the Nyquest diagram ((c) in Figure 6), the aluminum alloy material of Example 1 and the A380 alloy show similar capacitor ring patterns. However, the capacitor ring diameter of the aluminum alloy material of Example 1 is larger, indicating that it has better capacitance performance and higher charge transfer resistance. Fitting was performed using the equivalent circuit shown in Figure 7, and the results are shown in Table 5. R of the alloy of the aluminum alloy material of Example 1 sl Or R ct Both are higher than A380 alloy, indicating that it has better corrosion resistance.

[0410] In the equivalent circuit diagram 7, R s Represents the solution resistance associated with the corrosion solution used in the test, R sl 、R ct The surface resistance and charge transfer resistance of each alloy used as the working electrode are represented by the constant phase element (CPE), which represents the deviation of the capacitance in the EIS from the ideal capacitance behavior. n is used as an indicator to evaluate the degree of closeness between the actual experiment and the theoretical calculation. Q1 and Q2 represent the surface and charge transfer layer capacitances during the corrosion cell establishment process, corresponding to n1 and n2, respectively.

[0411] Table 5. EIS equivalent circuit parameters of the aluminum alloy material of Example 1 and the A380 alloy of Comparative Example 3

[0412] The potentiodynamic polarization curve of the aluminum alloy material in Example 1 can be found in FIG8 , where the horizontal axis is the chemical potential (unit is V) and the vertical axis is the current density (A / cm 2 ).

[0413] The potentiodynamic polarization curves of the aluminum alloy material (N1 alloy) in Example 1 are similar to those of the A380 alloy, and the N1 alloy also does not show passivation. corr ) is lower than that of A380 alloy, but the corrosion current density (I corr ) is only 46.9% of that of A380 alloy, and its polarization resistance (R p ) is also higher, so its corrosion resistance is better than that of A380 alloy.

[0414] The surface macromorphology of the alloy material of Example 1 (N1 alloy) at different corrosion times in the salt spray corrosion test can be seen in Figure 9. The corrosion rate of the alloy material of Example 1 (N1 alloy) is much lower than that of the A380 alloy, indicating that the N1 alloy has better corrosion resistance.

[0415] According to the results of the immersion corrosion test, the corrosion rates of the alloy material of Example 1 (N1 alloy) were only 41.3%, 49% and 50.5% of that of the A380 alloy after corrosion for 10d, 20d and 30d, respectively, indicating that it has very excellent corrosion resistance compared with the A380 alloy.

[0416] Tensile test results show that the aluminum alloy material of Example 1 (Aluminum Alloy N1) exhibits improved tensile strength compared to the A380 alloy, with an elongation of 5.42%, over 2.5 times that of the A380 alloy under the same treatment conditions. Alloy N1's elongation remains higher than that of the A380 alloy after 15 days of corrosion, and at 25 days, its elongation reaches 77.8% of that of the A380 alloy. At the same corrosion time, both the strength and elongation of the A380 alloy are lower than those of the new alloy N1, demonstrating that the new alloy exhibits superior mechanical properties and corrosion resistance to the A380 alloy. See Table 6 for details.

[0417] Table 6. Comparison of mechanical properties of the aluminum alloy material of Example 1 (aluminum alloy N1) and comparative example 3 (aluminum alloy A380)

[0418] The results of the mechanical property tests and corrosion rate analysis of each embodiment and each comparative example are also summarized in Table 7.

[0419] Table 7.

[0420] Taking Comparative Example 3 as an example, the test analysis results of each comparative example are described.

[0421] In Comparative Example 3, the A380 alloy is mainly composed of a columnar or nearly equiaxed α-Al matrix phase and a fine Al-Si eutectic structure. In addition, there are some bone-like or needle-like alloy phases near the eutectic structure. Part of the Cu element in the A380 alloy is dissolved in the α-Al matrix; the other part forms a bone-like or needle-like Cu-rich phase, which is identified as an Al2Cu phase by elemental analysis.

[0422] A salt spray corrosion test was conducted on the A380 die-cast aluminum alloy (Comparative Example 3), and the surface macromorphology of the samples at different corrosion times was analyzed. The A380 alloy was severely corroded, and the sample accumulated a large amount of white corrosion products. Due to the occurrence of general corrosion, the alloy surface was quickly covered with corrosion products when the corrosion time was relatively short (1-6 days). Subsequently, the accumulation area and thickness of the surface corrosion products continued to increase with the extension of the corrosion time. The sample surface showed a transition from the initial dark color of corrosion to being covered with a large amount of white corrosion products.

[0423] Microstructures of the A380 die-cast aluminum alloy (Comparative Example 3) during the early and late stages of the salt spray corrosion test showed that the A380 alloy exhibited uniform corrosion morphology. Furthermore, the corrosion was severe, with a high number of corrosion products. The corrosion products on the surface of the A380 alloy were numerous and thick.

[0424] The microstructure of the die-cast aluminum alloy A380 (Comparative Example 3) after removing the corrosion products shows that a large number of corrosion pits are distributed around the Al-Si eutectic structure of the A380 alloy. Because the Al2Cu phase is distributed near the Al-Si eutectic structure, the intergranular corrosion tendency of the Al-Si eutectic structure is further aggravated. In addition, the solid solution of a small amount of Cu in the matrix will increase the potential difference between the intergranular and intragranular, and the potential of the Al2Cu 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 a cathode phase, forming an electrochemical micro-battery with the nearby Cu-rich matrix phase and Al2Cu phase locally, causing the Cu-poor solid solution matrix phase to continuously corrode, resulting in the disappearance of grain boundaries.

[0425] The analysis results of the mass loss and corresponding corrosion rate of A380 die-cast aluminum alloy (Comparative Example 3) under different salt spray corrosion times show that the corrosion weight loss and corrosion rate of A380 alloy are both higher.

[0426] According to the test and analysis results of the tensile test, the changing trends of the mechanical properties and corrosion time were analyzed. It was found that the yield strength and tensile strength of the A380 alloy (Comparative Example 3) showed a rapid downward trend with the increase of corrosion time, which was particularly obvious in the early stage of corrosion (1-4d). The yield strength and tensile strength dropped to 77.5% and 76% of the values ​​before corrosion, respectively. Subsequently, the rate of performance degradation slowed down, and the yield strength and tensile strength finally dropped to 65.4% and 52.5% of the values ​​before corrosion, respectively.

[0427] The above description of various embodiments and examples tends to emphasize the differences between the various embodiments and examples. The same or similar aspects can be referenced to each other and will not be repeated here for the sake of brevity.

[0428] The various technical features of the above-described implementation methods or examples can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the above-described implementation methods or examples are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0429] It should be noted that the present application is not limited to the above-mentioned embodiments and examples. The above-mentioned embodiments and examples are only examples, and within the scope of the technical solution of the present application, embodiments that have substantially the same structure as the technical idea and exert the same effect are all included in the technical scope of the present application. The above embodiments and examples only express several embodiments of the present application, and their descriptions are relatively detailed, but they cannot be understood as limiting the scope of the patent. In addition, without departing from the scope of the subject matter of the present application, other methods of applying various modifications that can be thought of by those skilled in the art to the above embodiments or examples, and combining some of the constituent elements in the embodiments or examples to construct the above embodiments are also included in the scope of the present application.

Claims

1. An aluminum alloy material, wherein: The aluminum alloy material includes the following constituent elements by mass percentage: 6% to 11% Si, 0.5% to 0.9% Cu, 0.1% to 0.4% Ti, 0.2% to 0.6% Mg, 0.25% to 0.6% Zn, 0.5% to 1.1% Mn, 0.01% to 0.05% Sr, matrix element Al and unavoidable impurity elements; The aluminum alloy material may include or exclude an Al2Cu phase, and the mass fraction of the Al2Cu phase in the aluminum alloy material is ≤1.3%.

2. The aluminum alloy material according to claim 1, which satisfies one or both of the following characteristics: The mass percentage of Cu element in the aluminum alloy material is 0.5% to 0.8%; The aluminum alloy material comprises an Al2Cu phase, and the mass fraction of the Al2Cu phase in the aluminum alloy material is 0.1% to 1.3%.

3. The aluminum alloy material according to claim 1 or 2, which satisfies one or both of the following characteristics: The mass percentage of Cu element in the aluminum alloy material is 0.6% to 0.8%; The aluminum alloy material comprises an Al2Cu phase, and the mass fraction of the Al2Cu phase in the aluminum alloy material is 0.8% to 1.3%.

4. The aluminum alloy material according to any one of claims 1 to 3, wherein The aluminum alloy material includes a fibrous Al-Si eutectic structure; The aluminum alloy material includes an Al3Ti strengthening phase.

5. The aluminum alloy material according to claim 4, which satisfies one, two or three of the following characteristics: The mass percentage of Si element in the aluminum alloy material is 6.5% to 11%; The mass percentage of Ti element in the aluminum alloy material is 0.2% to 0.4%; The mass fraction of the Al3Ti strengthening phase in the aluminum alloy material is 0.3% to 2%.

6. The aluminum alloy material according to claim 4 or 5, which satisfies one, two or three of the following characteristics: The mass percentage of Si element in the aluminum alloy material is 8% to 11%; The mass percentage of Ti element in the aluminum alloy material is 0.25% to 0.4%; The mass fraction of the Al3Ti strengthening phase in the aluminum alloy material is 0.3% to 1%, and can be optionally 0.35% to 0.6%.

7. The aluminum alloy material according to any one of claims 1 to 6, wherein The aluminum alloy material may or may not include a Mg2Si phase, and the mass fraction of the Mg2Si phase in the aluminum alloy material is ≤0.05%, and may be 0%.

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

9. The aluminum alloy material according to claim 7 or 8, which satisfies one or both of the following characteristics: The mass percentage of Mg element in the aluminum alloy material is 0.3% to 0.5%; The mass percentage of Zn element in the aluminum alloy material is 0.4% to 0.6%; The mass ratio of Mg element to 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 to 9, wherein The unavoidable impurity elements include Fe element.

11. The aluminum alloy material according to any one of claims 1 to 10, which satisfies one or two of the following characteristics: The mass percentage of Mn element in the aluminum alloy material is 0.7% to 1.1%, and can be optionally 0.8% to 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 the AlSiMnFe phase.

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

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

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

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

16. An aluminum alloy structural part, wherein: The aluminum alloy structural part is a formed body of the aluminum alloy material according to any one of claims 1 to 15.

17. A method for preparing an aluminum alloy structural part, comprising the following steps: The aluminum ingot is heated and melted, and the ingredients determined by the nominal composition of the aluminum alloy material according to any one of claims 1 to 15 are added in the form of a master alloy, and then smelting and slagging are performed to prepare an aluminum alloy refined melt; Casting the aluminum alloy molten metal to obtain an aluminum alloy ingot; The aluminum alloy ingot is heat treated and cooled to obtain the aluminum alloy structural part.

18. A battery box, wherein: The battery box meets at least one of the following characteristics: At least a portion of the structural parts of the battery case comprises the aluminum alloy material according to any one of claims 1 to 15; The battery case comprises the aluminum alloy structural member according to claim 16; and The battery case includes an aluminum alloy structural part prepared by the method for preparing an aluminum alloy structural part according to claim 17.

19. A battery system, wherein: The battery system comprises the battery case as claimed in claim 18 and a battery cell located inside the battery case.

20. The battery system according to claim 19, wherein: The battery cell includes a liquid electrolyte.

21. An electrical device, comprising at least one of the aluminum alloy material according to any one of claims 1 to 15, the aluminum alloy structural part according to claim 16, the aluminum alloy structural part prepared by the method for preparing the aluminum alloy structural part according to claim 17, the battery case according to claim 18, and the battery system according to claim 19 or 20.

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

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