Lithium-aluminum alloy negative electrode, preparation method and all-solid-state battery

Abstract

The invention provides a lithium-aluminum alloy negative electrode, a preparation method and an all-solid-state battery, and belongs to the field of all-solid-state batteries. The lithium-aluminum alloy negative electrode comprises the following raw materials: an A356 aluminum alloy sheet, an aluminum metal film and a lithium sheet; wherein the aluminum metal film is arranged between the lithium sheet and the A356 aluminum alloy sheet. An A356 aluminum alloy sheet is used as a basic support material of the lithium-aluminum alloy negative electrode, and an A356 alloy is used for providing aluminum components; the aluminum metal film serves as a key isolation layer and is located between the lithium sheet and the A356 aluminum alloy sheet, direct contact between the lithium sheet and the A356 aluminum alloy sheet is effectively prevented, meanwhile, the aluminum oxide layer on the surface of the aluminum metal film provides additional chemical stability, rapid reaction between lithium and aluminum is prevented, and therefore loss of lithium active substances and interface corrosion are reduced; a lithium sheet is used as a main active material of a negative electrode, and lithium ions are provided in the charging and discharging process of the battery. According to the obtained lithium-aluminum alloy negative electrode, the interface stability of the negative electrode and the chalcogenide solid electrolyte is improved.

Description

Technical Field

[0001] The present application relates to the technical field of all-solid-state batteries, and in particular to a lithium-aluminum alloy negative electrode and a preparation method, and an all-solid-state battery. Background Art

[0002] Lithium-ion batteries based on traditional liquid electrolytes have been widely used in daily life, but liquid organic electrolytes have the disadvantages of being flammable, volatile, and leaky, posing a great safety hazard to the battery. Therefore, using safer solid electrolytes to replace traditional organic electrolytes has become the general trend of future battery development. In recent years, all-solid-state batteries designed using sulfur-based solid electrolytes with high lithium ion conductivity have attracted widespread attention from researchers. Sulfur-based solid electrolytes have high lithium ion conductivity, which can reduce the overall internal resistance of the battery; they are soft in texture and easy to form in one step.

[0003] However, sulfur-based solid electrolytes have a narrow electrochemical window and are unstable to lithium metal. When in contact with lithium metal, they will be reduced, consume the metallic lithium in the negative electrode, and generate byproducts with low lithium ion conductivity, which increases the interface impedance between the negative electrode and the electrolyte, and ultimately causes the rapid attenuation of battery performance. Therefore, how to improve the interface stability between the negative electrode and sulfur-based solid electrolytes is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present application provides a lithium-aluminum alloy negative electrode and a preparation method, and an all-solid-state battery to solve the following technical problem: how to improve the interface stability between the negative electrode and the sulfur-based solid electrolyte.

[0005] In a first aspect, the present application provides a lithium aluminum alloy negative electrode, characterized in that the raw materials of the lithium aluminum alloy negative electrode include: A356 aluminum alloy sheet, aluminum metal film and lithium sheet; wherein

[0006] The aluminum metal film is disposed between the lithium sheet and the A356 aluminum alloy sheet;

[0007] The molar ratio of lithium element to aluminum element in the lithium aluminum alloy negative electrode is (0.01-15):1.

[0008] Optionally, the molar ratio of lithium element to aluminum element in the lithium-aluminum alloy negative electrode is (0.02-10):1.

[0009] Optionally, the aluminum metal film includes: aluminum foil.

[0010] Optionally, the thickness of the aluminum foil is 10 μm to 50 μm.

[0011] In a second aspect, the present application provides a method for preparing a lithium aluminum alloy negative electrode according to any one embodiment of the first aspect, the method comprising:

[0012] Pre-treating the A356 aluminum alloy sheet and the lithium sheet;

[0013] The pretreated A356 aluminum alloy sheet, the aluminum metal film and the pretreated lithium sheet are stacked in sequence, and then pressed at a set pressure to obtain a lithium aluminum alloy negative electrode.

[0014] Optionally, the set pressure is 400MPa to 600MPa.

[0015] Optionally, the pretreatment of the A356 aluminum alloy sheet and the lithium sheet includes:

[0016] Impurities on the surfaces of the A356 aluminum alloy sheet and the lithium sheet are removed until the surfaces of the A356 aluminum alloy sheet and the lithium sheet are smooth.

[0017] In a third aspect, the present application provides an all-solid-state battery, comprising: a lithium-aluminum alloy negative electrode, a positive electrode, and a sulfide solid electrolyte as described in any one embodiment of the first aspect; wherein

[0018] Optionally, the positive electrode slurry includes: a positive electrode active material, a conductive agent and a binder;

[0019] The positive electrode active material includes: one or more of lithium cobalt oxide ternary material, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate and lithium nickel manganese oxide;

[0020] The conductive agent includes: one or more of carbon black, graphite powder, graphene, and carbon nanotubes;

[0021] The binder includes: one or more of polyvinylidene fluoride, sodium alginate, polyvinyl alcohol, polymethyl methacrylate, polytetrafluoroethylene, and polyacrylic acid.

[0022] Optionally, the sulfide solid electrolyte includes: Li 10 GeP2S 12 , Li6PS5X or Li2SP2S5, wherein X is Cl, Br or I.

[0023] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0024] The present application provides a lithium aluminum alloy negative electrode, the raw materials of which include: A356 aluminum alloy sheet, aluminum metal film and lithium sheet; wherein the aluminum metal film is arranged between the lithium sheet and the A356 aluminum alloy sheet; the molar ratio of lithium element to aluminum element in the lithium aluminum alloy negative electrode is (0.01-15):1. The A356 aluminum alloy sheet is used as the basic supporting material of the lithium aluminum alloy negative electrode, and the A356 alloy is used to provide the aluminum component; the aluminum metal film is used as the key isolation layer, which is located between the lithium sheet and the A356 aluminum alloy sheet, effectively preventing the direct contact between the two, and the aluminum oxide layer on its surface provides additional chemical stability, preventing the rapid reaction between lithium and aluminum, thereby reducing the loss of lithium active substances and interface corrosion; the lithium sheet is used as the main active material of the negative electrode, providing lithium ions during the battery charging and discharging process. The lithium aluminum alloy negative electrode thus obtained improves the interface stability between the negative electrode and the sulfur-based solid electrolyte. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0027] Figure 1 A schematic diagram of a lithium aluminum alloy negative electrode provided in an embodiment of the present application;

[0028] Figure 2 A flow chart of a method for preparing a lithium aluminum alloy negative electrode provided in an embodiment of the present application;

[0029] Reference numerals:

[0030] 1-A356 aluminum alloy sheet, 2-aluminum metal film, 3-lithium sheet. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0032] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0033] In addition, in the description of the specification of the present application, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second", etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" means one or more, and "plurality" means two or more. "At least one", "the following at least one item (items)" or similar expressions refer to any combination of these items, including any combination of single items (items) or plural items (items). For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc or abc, where a, b, c can be single or plural, respectively.

[0034] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0035] The creative ideas of this application are:

[0036] Using alloy negative electrode to replace lithium metal negative electrode is an effective way to improve the stability of the interface between negative electrode and sulfur-based solid electrolyte. Among them, the high electronic conductivity of lithium aluminum alloy makes carbon-free negative electrode design possible, avoiding the decomposition of sulfide solid electrolyte caused by carbon. In addition, the good ductility and processability of aluminum avoid the use of binders and reduce the proportion of inactive substances in the negative electrode. At present, in the preparation of lithium aluminum alloy, aluminum foil is mainly used to provide aluminum components. However, when aluminum foil is used, the lithium aluminum oxide formed by the natural oxide layer on the surface of the aluminum foil during the alloying process will lead to the loss of lithium active substances.

[0037] Based on the above technical problems, the present invention uses A356 aluminum alloy to replace traditional aluminum foil, avoiding the problem of loss of lithium active materials caused by lithium aluminum oxide, while taking into account strength and density. However, due to the high activity of lithium, when it is directly pressed together with A356 cast aluminum alloy, a chemical reaction will occur, resulting in corrosion, oxidation or stratification at the material interface, thereby affecting the performance and service life of the overall material. Therefore, the inventor of the present application creatively sets an aluminum metal film between the two, and the aluminum metal film can effectively isolate the direct contact between lithium and A356 aluminum alloy, prevent the active lithium from reacting with aluminum in the aluminum alloy, thereby avoiding corrosion, oxidation and stratification. At the same time, the aluminum oxide layer (Al2O3) naturally formed on the aluminum metal film is dense, which can effectively improve the stability and corrosion resistance of the material. This oxide film not only serves as a physical barrier, but also can resist chemical erosion to a certain extent. The aluminum metal film has good compatibility with both side materials (lithium and A356 aluminum alloy), which is conducive to interface bonding, reduces interface resistance, and improves the conductivity and mechanical strength of the overall material. In addition, the thickness of the aluminum metal film is 10 μm to 50 μm, the amount used is small, and lithium aluminum oxide will not be formed during the alloying process.

[0038] Therefore, the present invention designs a lithium aluminum alloy negative electrode formed by pressing an A356 aluminum alloy sheet, an aluminum metal film and a lithium sheet, thereby improving the interface stability between the negative electrode and the sulfur-based solid electrolyte.

[0039] Figure 1 A schematic diagram of a lithium aluminum alloy negative electrode provided in an embodiment of the present application.

[0040] See also Figure 1 The present application provides a lithium aluminum alloy negative electrode, characterized in that the raw materials of the lithium aluminum alloy negative electrode include: A356 aluminum alloy sheet, aluminum metal film and lithium sheet; wherein

[0041] The aluminum metal film is disposed between the lithium sheet and the A356 aluminum alloy sheet;

[0042] The molar ratio of lithium element to aluminum element in the lithium aluminum alloy negative electrode is (0.01-15):1.

[0043] It should be noted that the main components of A356 aluminum alloy include silicon (Si), magnesium (Mg) and aluminum (Al). Among them, the silicon content is between 6.5% and 7.5%, and the high silicon content significantly improves its casting performance and corrosion resistance. The magnesium content is controlled between 0.20% and 0.40%, which helps to improve the strength and corrosion resistance of the alloy. In addition, the contents of elements such as iron (Fe), copper (Cu), manganese (Mn), zinc (Zn) and titanium (Ti) are strictly controlled within a lower threshold to ensure the high purity and performance consistency of the alloy. A356 aluminum alloy can maintain stable performance in a variety of environments and is not easily corroded. Mainly due to the synergistic effect of alloying elements, the intrusion of corrosive media is effectively prevented. At the same time, under stress, A356 aluminum alloy can still maintain good corrosion resistance and is not prone to stress corrosion cracking. This is especially important for parts that need to withstand complex stress and environmental conditions.

[0044] A356 aluminum alloy sheet is used as the basic supporting material. Due to its good mechanical properties, corrosion resistance and relatively low density, A356 aluminum alloy not only provides the structural strength of the negative electrode, but also can participate in the electrochemical reaction to a certain extent and contribute additional capacity. Aluminum metal film is used as a key isolation layer. The aluminum metal film is located between the lithium sheet and the A356 aluminum alloy sheet, effectively preventing direct contact between the two. The aluminum oxide layer on its surface provides additional chemical stability, preventing rapid reaction between lithium and aluminum, thereby reducing the loss of lithium active substances and interface corrosion. As the main active material of the negative electrode, the lithium sheet is responsible for providing lithium ions during the battery charging and discharging process. The high energy density of lithium gives the negative electrode a high theoretical capacity.

[0045] The molar ratio of lithium to aluminum in the lithium-aluminum alloy negative electrode is limited to (0.01-15):1, so as to avoid the lithium content being too low to play the role of the lithium metal negative electrode or the aluminum content being too low to meet the requirements of improving the stability of the interface between the negative electrode and the sulfur-based solid electrolyte. Exemplarily, the molar ratio of lithium to aluminum in the lithium-aluminum alloy negative electrode can be 0.01:1, 0.1:1, 0.5:1, 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, 12:1, 15:1, etc.

[0046] In some embodiments, the molar ratio of lithium element to aluminum element in the lithium aluminum alloy negative electrode is (0.02-10):1.

[0047] In some embodiments, the aluminum metal film includes: aluminum foil.

[0048] In some embodiments, the aluminum foil has a thickness of 10 μm to 50 μm.

[0049] Aluminum foil is a hot stamping material that is directly rolled into thin sheets with metal aluminum. Common models include 1235 aluminum foil, 8011 aluminum foil, 8079 aluminum foil, 3003 aluminum foil and 5052 aluminum foil. Aluminum foil is a common form of aluminum processed products, with mature production technology and low cost, suitable for large-scale production applications. Concretizing aluminum metal film into aluminum foil and selecting an appropriate thickness range is an effective method for preparing lithium aluminum alloy negative electrodes. This method not only utilizes the excellent properties of aluminum foil, but also controls cost and weight. Exemplarily, the thickness of the aluminum foil can be 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, etc.

[0050] Figure 2 A flow chart of a method for preparing a lithium aluminum alloy negative electrode provided in an embodiment of the present application.

[0051] See also Figure 2 The present application provides a method for preparing a lithium aluminum alloy negative electrode as described in any one embodiment of the first aspect, the method comprising:

[0052] S1, pre-treating the A356 aluminum alloy sheet and the lithium sheet;

[0053] It should be noted that appropriate physical or chemical methods, such as mechanical grinding, ultrasonic cleaning, chemical corrosion, etc., can be used to remove oxides, oil stains, dust and other impurities on the surface of the A356 aluminum alloy sheet and the lithium sheet.

[0054] In some embodiments, the pretreatment of the A356 aluminum alloy sheet and the lithium sheet comprises:

[0055] Impurities on the surfaces of the A356 aluminum alloy sheet and the lithium sheet are removed until the surfaces of the A356 aluminum alloy sheet and the lithium sheet are smooth.

[0056] Through pretreatment, impurities on the surface of the material are removed to ensure a smooth surface so that the layers can be tightly bonded during the subsequent pressing process, reducing the interface resistance and improving the stability of the overall negative electrode.

[0057] S2, stacking the pretreated A356 aluminum alloy sheet, the aluminum metal film and the pretreated lithium sheet in sequence, and then pressing them at a set pressure to obtain a lithium aluminum alloy negative electrode.

[0058] The pretreated A356 aluminum alloy sheet, aluminum metal film (aluminum foil) and lithium sheet are tightly combined into one by pressing at a set pressure to form a lithium-aluminum alloy negative electrode.

[0059] In some embodiments, the set pressure is 400 MPa to 600 MPa.

[0060] Applying a pressure of 400MPa to 600MPa can ensure full bonding and avoid dangerous reactions such as explosion of lithium sheets caused by overpressure. After standing, the desired lithium aluminum alloy is obtained. Exemplarily, the set pressure can be 400MPa, 420MPa, 450MPa, 480MPa, 500MPa, 520MPa, 550MPa, 580MPa, 600MPa, etc.

[0061] The product prepared by the method for preparing the lithium-aluminum alloy negative electrode is the above-mentioned lithium-aluminum alloy negative electrode. The chemical composition and structure of the lithium-aluminum alloy negative electrode prepared by the method for preparing the lithium-aluminum alloy negative electrode can refer to the above-mentioned embodiment. Since the method for preparing the lithium-aluminum alloy negative electrode adopts part or all of the technical solutions of the lithium-aluminum alloy negative electrode embodiment, it at least has all the beneficial effects brought by the technical solutions of the lithium-aluminum alloy negative electrode embodiment, which will not be described one by one here.

[0062] Based on an inventive concept, the present application provides an all-solid-state battery, the all-solid-state battery comprising: a lithium-aluminum alloy negative electrode, a positive electrode and a sulfide solid electrolyte as described in any one embodiment of the first aspect; wherein

[0063] In some embodiments, the positive electrode slurry includes: a positive electrode active material, a conductive agent and a binder;

[0064] The positive electrode active material includes: one or more of lithium cobalt oxide ternary material, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate and lithium nickel manganese oxide;

[0065] The conductive agent includes: one or more of carbon black, graphite powder, graphene, and carbon nanotubes;

[0066] The binder includes: one or more of polyvinylidene fluoride, sodium alginate, polyvinyl alcohol, polymethyl methacrylate, polytetrafluoroethylene, and polyacrylic acid.

[0067] In some embodiments, the sulfide solid electrolyte includes: Li 10 GeP2S 12 , Li6PS5X or Li2SP2S5, wherein X is Cl, Br or I.

[0068] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

[0069] Example 1

[0070] This embodiment provides a lithium aluminum alloy negative electrode, and the preparation method thereof comprises the following steps:

[0071] S11, pre-treating the lithium sheet to remove surface impurities until the surface of the lithium sheet is smooth, flat and free of impurities, and cutting the lithium sheet of required mass for standby use, the diameter of the lithium sheet is 15.6 mm, and the thickness is 0.5 mm; then pre-treating the surface of the A356 aluminum alloy sheet to remove impurities until the surface is smooth, flat and free of impurities, and taking the alloy of required mass for standby use, the diameter of the A356 aluminum alloy sheet is 15.6 mm, and the thickness is 0.5 mm;

[0072] S21. Place the pretreated A356 aluminum alloy sheet, the aluminum foil with a thickness of 10 μm, and the pretreated lithium sheet in a pressure mold, apply a pressure of 500 MPa, and obtain a lithium-aluminum alloy negative electrode after standing. The molar ratio of lithium element to aluminum element in the lithium-aluminum alloy negative electrode is 0.02:1.

[0073] Based on the above lithium aluminum alloy negative electrode, this embodiment also provides an all-solid-state battery, and its preparation method includes:

[0074] S12, mixing lithium cobalt oxide, carbon black and polyvinylidene fluoride in a mass ratio of 95:2.5:2.5 to obtain a positive electrode material;

[0075] S22, obtaining electrolyte powder Li 10 GeP2S 12 ;

[0076] S32, placing electrolyte powder in a mold, and pressing to obtain an electrolyte layer; spreading the positive electrode material on one side of the electrolyte layer, and placing a current collector, and pressing to form a positive electrode layer; placing the lithium aluminum alloy negative electrode on the other side of the electrolyte layer, and placing a current collector. After pressing, an all-solid-state battery is obtained.

[0077] Example 2

[0078] The difference between this embodiment and embodiment 1 is that the molar ratio of lithium element to aluminum element in the lithium aluminum alloy negative electrode is 0.8:1.

[0079] Example 3

[0080] The difference between this embodiment and embodiment 1 is that the molar ratio of lithium element to aluminum element in the lithium aluminum alloy negative electrode is 5:1.

[0081] Example 4

[0082] The difference between this embodiment and embodiment 1 is that the molar ratio of lithium element to aluminum element in the lithium aluminum alloy negative electrode is 10:1.

[0083] Comparative Example 1

[0084] The preparation method of the lithium aluminum alloy negative electrode in this comparative example comprises the following steps:

[0085] S13, removing impurities from the surface of the lithium sheet until the surface of the lithium sheet is smooth, flat and free of impurities, and cutting lithium sheets of required quality for later use;

[0086] S23, removing impurities from the surface of the aluminum foil until the surface of the aluminum foil is smooth, flat and free of impurities, and cutting the aluminum foil of required mass for use; taking the pretreated lithium sheet and the pretreated aluminum foil, placing them in a pressure mold, applying pressure, and standing to obtain the required lithium aluminum alloy;

[0087] S33, placing the lithium aluminum alloy and the current collector in a pressure mold, applying pressure, and standing to obtain the desired lithium aluminum alloy negative electrode. The molar ratio of lithium element to aluminum element in the lithium aluminum alloy negative electrode is 0.8:1.

[0088] Based on the above-mentioned lithium aluminum alloy negative electrode, this embodiment also provides an all-solid-state battery, and its preparation method is the same as the preparation method of the all-solid-state battery in Example 1.

[0089] The all-solid-state batteries obtained in Examples 1 to 4 and Comparative Example 1 were subjected to performance tests, and the results are shown in Table 1.

[0090] Performance of all-solid-state batteries obtained in Examples 1 to 4 and Comparative Example 1

[0091] Group Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Gram capacity (mAh / g) 1049.22 2267.22 3216.83 3509.18 1551.23

[0092] In addition, one or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0093] In the embodiment of the present invention, the lithium aluminum alloy negative electrode has a higher theoretical specific capacity than the traditional graphite negative electrode. This is because the lithium aluminum alloy can store more lithium ions, thereby increasing the energy density of the battery. This is of great significance for application scenarios that require high energy density, such as electric vehicles and portable electronic devices.

[0094] In the embodiment of the present invention, the volume expansion rate of the lithium aluminum alloy negative electrode is low during the charge and discharge process, which helps to maintain the stability of the battery structure and reduce performance degradation caused by volume change.

[0095] In the embodiment of the present invention, the lithium aluminum alloy negative electrode reduces the formation of lithium dendrites through the inhibitory effect of the aluminum metal film, thereby avoiding safety problems such as battery short circuit and heating.

[0096] In the embodiment of the present invention, the provision of the aluminum metal film can effectively prevent the electrolyte from directly contacting the lithium metal, thereby reducing the battery performance degradation and safety issues caused by the electrolyte corroding the lithium metal.

[0097] In the embodiment of the present invention, a simplified pressing method is adopted to obtain the required lithium aluminum alloy in a simple and effective manner.

[0098] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A lithium aluminum alloy negative electrode, characterized in that: The raw materials of the lithium aluminum alloy negative electrode include: A356 aluminum alloy sheet, aluminum metal film and lithium sheet; The aluminum metal film is disposed between the lithium sheet and the A356 aluminum alloy sheet; The molar ratio of lithium element to aluminum element in the lithium aluminum alloy negative electrode is (0.01-15):

1.

2. The lithium aluminum alloy negative electrode according to claim 1, characterized in that The molar ratio of lithium element to aluminum element in the lithium aluminum alloy negative electrode is (0.02-10):

1.

3. The lithium aluminum alloy negative electrode according to claim 1, characterized in that The aluminum metal film includes: aluminum foil.

4. The lithium aluminum alloy negative electrode according to claim 3, characterized in that: The thickness of the aluminum foil is 10 μm to 50 μm.

5. A method for preparing a lithium aluminum alloy negative electrode according to any one of claims 1 to 4, characterized in that: The method comprises: Pre-treating the A356 aluminum alloy sheet and the lithium sheet; The pretreated A356 aluminum alloy sheet, the aluminum metal film and the pretreated lithium sheet are stacked in sequence, and then pressed at a set pressure to obtain a lithium aluminum alloy negative electrode.

6. The method according to claim 5, characterized in that The set pressure is 400MPa to 600MPa.

7. The method according to claim 5, characterized in that The pretreatment of the A356 aluminum alloy sheet and the lithium sheet comprises: Impurities on the surfaces of the A356 aluminum alloy sheet and the lithium sheet are removed until the surfaces of the A356 aluminum alloy sheet and the lithium sheet are smooth.

8. An all-solid-state battery, characterized in that: The all-solid-state battery comprises: a lithium-aluminum alloy negative electrode, a positive electrode and a sulfide solid electrolyte as described in any one of claims 1 to 4.

9. The all-solid-state battery according to claim 8, characterized in that: The positive electrode slurry comprises: a positive electrode active material, a conductive agent and a binder; wherein The positive electrode active material includes: one or more of lithium cobalt oxide ternary material, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate and lithium nickel manganese oxide; The conductive agent includes: one or more of carbon black, graphite powder, graphene, and carbon nanotubes; The binder includes: one or more of polyvinylidene fluoride, sodium alginate, polyvinyl alcohol, polymethyl methacrylate, polytetrafluoroethylene, and polyacrylic acid.

10. The all-solid-state battery according to claim 8, characterized in that: The sulfide solid electrolyte includes: Li 10 GeP2S 12 , Li6PS5X or Li2SP2S5, wherein X is Cl, Br or I.

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