Metal lithium composite material and processing method, application and production system thereof, and metal lithium composite membrane

Abstract

The invention discloses a metal lithium composite material and a processing method, application and production system thereof, and the metal composite material comprises a metal lithium or lithium alloy matrix and an MXene nanosheet; and the MXene nanosheets are of an oriented layered arrangement structure in the matrix. The processing method of the metal composite material comprises the following steps: mixing molten metal lithium or lithium alloy with MXene nanosheets to obtain mixed lithium slurry; cooling and curing the mixed lithium slurry to obtain a composite lithium ingot; and the composite lithium ingot is formed through extrusion and / or rolling. The air stability of the metal lithium composite material can be improved, and meanwhile, the mechanical property is also improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metal materials, and particularly relates to a metal lithium composite material and a processing method, application, production system and metal lithium composite film thereof. BACKGROUND

[0002] Metal lithium has high chemical activity, and exposure to air can cause various uncontrollable adverse reactions, producing heterogeneous pollutants and uneven surfaces, especially when reacting with moisture, which causes serious safety hazards, which seriously limits the industrial application scenarios of metal lithium.

[0003] In addition, there are two difficulties in the processing of metal lithium materials at present: first, the mechanical properties of metal lithium itself are extremely poor, and the texture is very soft, so when the metal lithium is mechanically rolled to below 50 μm, the metal lithium belt is easy to break; when rolled to a thickness of 20 μm or even below, the metal lithium will adhere to the high polymer base material due to the pressure applied by the roller, and cannot be separated from the base to obtain a continuous ultra-thin lithium belt. At the same time, because the hardness of metal lithium is low, it is easy to deform during rolling, which requires high precision of the rolling equipment for preparing ultra-thin lithium, thereby increasing the cost of preparing ultra-thin lithium. Second, when using a melting method to prepare ultra-thin lithium, the liquid lithium metal will be spherical droplets on the substrate due to the large tension, which is not conducive to the spreading and deep processing of metal lithium on the substrate, and it is difficult to obtain a uniform thickness of ultra-thin lithium belt. SUMMARY

[0004] In view of the technical problem of high chemical activity of metal lithium and poor air stability, the present application provides a metal lithium composite material with a directional layered arrangement structure of MXene nanosheets in a metal lithium or lithium alloy substrate and a processing method thereof. The processing method can improve the air stability of the metal lithium composite material, and also improve the mechanical properties (including hardness and tensile strength), thereby obtaining a continuous and uniform thickness of the metal lithium composite material.

[0005] The first aspect of the present application provides a metal lithium composite material, which comprises: a substrate of metal lithium or lithium alloy material and MXene nanosheets; the MXene nanosheets are arranged in a directional layered arrangement structure in the substrate.

[0006] In some embodiments, the thickness of the above-mentioned metal lithium composite material is ≤1000 μm; preferably, the thickness is ≤500 μm; more preferably, the thickness is ≤200 μm; more preferably, the thickness is ≤100 μm; more preferably, the thickness is ≤50 μm; more preferably, the thickness is ≤20 μm; more preferably, the thickness is ≤10 μm.

[0007] In some embodiments, the chemical formula of the above-mentioned MXene is represented as: M n+1 Xn T x , wherein M represents one or more of transition metal elements Ti, V, Mo, Nb, Ta, W, Zr, Y, X represents one or more of carbon, nitrogen or boron elements, T x represents containing functional groups; 1≤n≤4.

[0008] In some embodiments, the functional groups of the MXene contain fluorine elements.

[0009] In some embodiments, the M of the MXene is Ti element, the X is carbon element, and the T x contains fluorine elements.

[0010] In some embodiments, the alloying elements of the lithium alloy are selected from one or more of Na, Mg, Al, Zn, Sn, V, In, Ag, Au, B, Si, Ge.

[0011] In some embodiments, the lithium content in the lithium alloy is between 0.1wt.% and 99.9wt.%.

[0012] In some embodiments, the mass ratio of the MXene to the metallic lithium or the metallic lithium in the alloy is between (0.01-1):1; preferably, between (0.1-0.5):1.

[0013] In some embodiments, the surface of the metallic lithium composite material has MXene nanosheet coverage; or, the surface of the metallic lithium composite material shows MXene nanosheet coverage after metal corrosion.

[0014] In some embodiments, the metallic lithium composite material described above forms the oriented layered arrangement structure by the following method: mixing molten metallic lithium or lithium alloy with MXene nanosheets to obtain a mixed lithium slurry; cooling and solidifying the mixed lithium slurry to obtain a composite lithium ingot; and extruding and / or rolling the composite lithium ingot into a sheet or foil; in the process of extruding and / or rolling, the MXene nanosheets form the oriented layered arrangement structure inside the metallic lithium matrix.

[0015] In some embodiments, the oriented layered arrangement structure in the metallic lithium composite material described above is characterized by scanning electron microscopy test; more preferably, the metallic lithium in the metallic lithium composite material is peeled off before the scanning electron microscopy test.

[0016] In some embodiments, the surface of the metallic lithium composite material has MXene nanosheet coverage, which can be characterized by scanning electron microscopy test to show that the surface has two-dimensional nanosheet coverage, or after etching the surface metal of the metallic lithium composite material, the scanning electron microscopy test shows that the surface has two-dimensional nanosheet coverage, and the two-dimensional nanosheet is MXene nanosheet.

[0017] In some embodiments, the X-ray diffraction (XRD) characterization of the above-mentioned metal lithium composite material has a (002) diffraction peak of MXene, a metal lithium (110) crystal face and a (200) crystal face diffraction peak; the intensity ratio of the metal lithium (110) crystal face and the (200) crystal face diffraction peak is greater than 2.6.

[0018] In some embodiments, the X-ray diffraction (XRD) characterization of the above-mentioned metal lithium composite material has a (002) diffraction peak of MXene, a metal lithium (110) crystal face and a (200) crystal face diffraction peak; the intensity ratio of the metal lithium (110) crystal face and the (200) crystal face diffraction peak is greater than 2.6; preferably, the ratio is greater than 4.2, more preferably, the ratio is greater than 5.2; more preferably, the ratio is greater than 7.6.

[0019] The second aspect of the present application provides a processing method of a metal lithium composite material, comprising the following steps: mixing molten metal lithium or lithium alloy with MXene to obtain a mixed lithium slurry; cooling and solidifying the mixed lithium slurry to obtain a composite lithium ingot; and extruding and / or rolling the composite lithium ingot into a shape.

[0020] In some embodiments, the thickness of the above-mentioned metal lithium composite material is ≤1000 μm; preferably, the thickness is ≤500 μm; more preferably, the thickness is ≤200 μm; more preferably, the thickness is ≤100 μm; more preferably, the thickness is ≤50 μm; more preferably, the thickness is ≤20 μm; more preferably, the thickness is ≤10 μm.

[0021] In some embodiments, in the above-mentioned processing method, the composite lithium ingot is first extruded into a composite lithium sheet, and then the composite lithium sheet is rolled several times to obtain a composite lithium foil with a reduced thickness.

[0022] In some embodiments, the thickness of the above-mentioned composite lithium foil is ≤100 μm; more preferably, the thickness is ≤50 μm; more preferably, the thickness is ≤20 μm; more preferably, the thickness is ≤10 μm.

[0023] In some embodiments, a film layer is arranged on one side or both sides of the composite lithium sheet during the rolling process.

[0024] In some embodiments, the film layer is made of a high polymer material and / or a metal material.

[0025] In some embodiments, the high polymer material is polyethylene terephthalate (PET), polyimide (PI), polypropylene (PP) or polyethylene (PE); and the metal material is a copper foil, a nickel foil, a stainless steel foil, an aluminum foil or a titanium foil.

[0026] In some embodiments, the X-ray diffraction (XRD) characterization of the above-mentioned metal lithium composite material has a (002) diffraction peak of MXene, a metal lithium (110) crystal face and a (200) crystal face diffraction peak; the intensity ratio of the metal lithium (110) crystal face and the (200) crystal face diffraction peak is greater than 2.6; preferably, the ratio is greater than 4.2, more preferably, the ratio is greater than 5.2; and more preferably, the ratio is greater than 7.6.

[0027] In some embodiments, the above-mentioned MXene presents a directional layered arrangement structure in the metal lithium composite material; the metal lithium composite material can be characterized by a scanning electron microscope test to show a directional layered arrangement structure of MXene nanosheets; and preferably, the metal lithium in the metal lithium composite material is peeled off before the scanning electron microscope test.

[0028] In some embodiments, the surface of the above-mentioned metal lithium composite material has a MXene nanosheet coverage, and the scanning electron microscope test of the metal lithium composite material shows that the surface has a two-dimensional nanosheet coverage. In some embodiments, the two-dimensional nanosheet coverage is shown after the surface of the metal composite material is slightly etched before the test characterization, and the two-dimensional nanosheet is a MXene nanosheet.

[0029] In some embodiments, the chemical formula of the above-mentioned MXene is represented as: MXnT n+1 X n T x , wherein M represents one or more of transition metal elements Ti, V, Mo, Nb, Ta, W, Zr, Y, X represents one or more of carbon, nitrogen or boron elements, T x represents a functional group containing; 1≤n≤4; preferably, the functional group contains fluorine element; and most preferably, M in the MXene is Ti element, X is carbon element, and T x contains fluorine element.

[0030] In some embodiments, the alloying element in the above-mentioned lithium alloy is selected from one or more of Na, Mg, Al, Zn, Sn, V, In, Ag, Au, B, Si, Ge.

[0031] In some embodiments, the lithium content in the above-mentioned lithium alloy is between 0.1wt.% and 99.9wt.%.

[0032] In some embodiments, the mass ratio of the above-mentioned MXene to the metal lithium in the metal lithium or alloy is between (0.01-1):1; and preferably, between (0.1-0.5):1.

[0033] In some embodiments, the MXene is added in an amount of 0.1-50 parts by weight, preferably 0.1-30 parts by weight, more preferably 0.1-20 parts by weight, more preferably 0.1-10 parts by weight, and most preferably 5-10 parts by weight, based on 100 parts by weight of the lithium metal or lithium alloy.

[0034] In some embodiments, the lithium metal composite has a tensile strength of 3 times or more that of the same size of lithium metal.

[0035] In some embodiments, the lithium metal composite has a hardness of 10 times or more that of the same size of lithium metal, preferably 20 times or more, and more preferably 30 times or more.

[0036] In some embodiments, the lithium metal composite maintains metallic luster in air for 1 h or more, preferably 2 h or more, more preferably 2 h or more, more preferably 3 h or more, more preferably 4 h or more, more preferably 5 h or more, and more preferably 6 h or more.

[0037] In a third aspect, the present application provides a lithium metal composite as described above, or a lithium metal composite obtained by the processing method as described above, for use as an electrode material or a lithium supplement material in a lithium battery, or for use in the field of metallurgy to manufacture lightweight alloys.

[0038] In a fourth aspect, the present application provides a production system for a lithium metal composite, comprising: an inert gas system, a melting device, a cooling and solidification device, an extrusion device, and / or a rolling device; the inert gas system comprises an inert gas environment bin, and the melting device and the cooling and solidification device are arranged in the inert gas environment bin; the melting device comprises a heater, a container, and a stirring device, and is used for heating and melting lithium metal or lithium alloy, mixing with MXene powder to obtain a mixed lithium liquid; the cooling and solidification device comprises a mold, and is used for cooling and solidifying the mixed lithium liquid to obtain a composite lithium ingot; the extrusion device is used for extruding the composite lithium ingot into a composite lithium sheet or a composite lithium foil; the rolling device is used for rolling the composite lithium ingot into a composite lithium sheet or a composite lithium foil, or is used for rolling the extruded composite lithium sheet into a composite lithium foil.

[0039] In some embodiments, the production system further comprises a slitting device for slitting the composite lithium sheet or the composite lithium foil into a predetermined shape.

[0040] In some embodiments, the production system further comprises a winding device for winding the composite lithium sheet or the composite lithium foil.

[0041] In some embodiments, the production system further comprises a film coating device for providing a film layer on one side or both sides of the composite lithium sheet before the rolling step.

[0042] In some embodiments, the production system further comprises the film coating device and a film stripping device for stripping the film layer after the rolling step.

[0043] In some embodiments, the production system further comprises a dry room system for controlling the moisture in the environment, and the extrusion device and / or the rolling device are in the environment of the dry room system.

[0044] In some embodiments, the film layer is made of a polymer material and / or a metal material.

[0045] In some embodiments, the polymer material is polyethylene terephthalate (PET), polyimide (PI), polypropylene (PP), or polyethylene (PE); and the metal material is a copper foil, an aluminum foil, a nickel foil, a stainless steel foil, or a titanium foil.

[0046] In some embodiments, the polymer material is polyethylene terephthalate (PET), polyimide (PI), polypropylene (PP), or polyethylene (PE); and the metal material is a copper foil, an aluminum foil, a nickel foil, a stainless steel foil, or a titanium foil.

[0047] Compared with the prior art, the beneficial technology of the present application is that:

[0048] (1) The directional layered arrangement structure of the MXene nanosheets in the metal lithium composite material of the present application can effectively prevent the corrosion of corrosive substances (such as air) on the lithium metal, showing excellent air stability, greatly reducing the harsh requirements on environmental conditions in the production process of the metal lithium material, and reducing the danger of production. (2) The metal lithium composite material of the present application has excellent mechanical properties, including tensile strength and hardness, showing excellent continuity and self-supporting property. (3) The processing method of the present application is simple and suitable for industrialized mass production; in particular, the processing method of the present application can also realize the processing and production of ultra-thin composite lithium foil (thickness ≤ 50 μm, especially ≤ 20 μm), and the obtained ultra-thin composite lithium foil has smooth surface, uniform thickness, and excellent continuity and self-supporting property. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 It is a schematic diagram of the processing method of the present application, and the disordered and dispersed MXene nanosheets form a directional layered arrangement structure under the action of shearing force.

[0050] Figure 2 It is a thickness test photo of the ultra-thin composite lithium foil obtained in Example 2 of the present application, and the result shows that the thickness is 13 μm.

[0051] Figure 3 SEM photos of the surface of the ultrathin composite lithium foil obtained in Example 2 of the present application.

[0052] Figure 4 SEM photos of the cross section of the composite lithium foil obtained in Example 2 of the present application after stripping the metal lithium.

[0053] Figure 5 SEM photos of the cross section of the ultrathin composite lithium foil with a thickness of 9 microns obtained in Example 2 of the present application.

[0054] Figure 6 For the air stability test of the metal lithium sheet, the comparative lithium foil and the composite lithium foil in Example 2 of the present application, the test wafer was placed in the air, and the surface property change was observed at different times.

[0055] Figure 7 For the comparative diagram of the XRD spectra of the metal lithium sheet, the comparative lithium foil and the composite lithium foil in Example 2 of the present application.

[0056] Figure 8 For the comparative diagram of the XRD spectra of the composite lithium foils with different thicknesses in Example 2 of the present application.

[0057] Figure 9 For the hardness test results of the metal lithium foil, the composite lithium foil and the comparative lithium foil in Example 2 of the present application.

[0058] Figure 10 For the tensile test results of the composite lithium foils with different MXene contents, the comparative lithium foil and the metal lithium foil in Example 3 of the present application.

[0059] Figure 11 For the electrochemical performance test results of the composite lithium electrode placed in the air for 24 hours in Example 4 of the present application.

[0060] Figure 12 For the schematic diagram of a production system of a metal lithium composite material in Example 5 of the present application.

[0061] Figure 13 For the schematic diagram of another production system of a metal lithium composite material in Example 6 of the present application.

[0062] Figure 14 For the tensile test results of different composite aluminum lithium alloy foil samples in Example 9 of the present application.

[0063] Figure 15 For the SEM photos of the corrosion test of the aluminum lithium alloy foil (AL) in Example 9 of the present application.

[0064] Figure 16SEM photos for corrosion test of the composite aluminum-lithium alloy foil (A-1L-0.5MX) in Example 9 of the present application.

[0065] Figure 17 Tensile property test results of the different composition lead foil and composite lead-lithium foil samples in Example 10 of the present application.

[0066] Main reference signs:

[0067] 10-inert gas system, 11-inert gas environment bin; 20-melting device, 21-heater, 22-vessel, 23-stirring device; 30-cooling and solidifying device, 31-mold; 40-extruding device; 50-rolling device; 60-slitting device; 70-laminating device; 80-stripping device; 90-winding device;

[0068] 100-mixed lithium liquid; 200-composite lithium sheet; 300-composite lithium foil; 400-laminated film; 500-laminated film-lithium foil-laminated film composite layer. DETAILED DESCRIPTION

[0069] The technical solutions of the present application are illustrated below by specific examples. It should be understood that the one or more steps mentioned in the present application do not exclude the existence of other methods and steps before and after the combination steps, or other methods and steps can be inserted between these explicitly mentioned steps. It should also be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. Unless otherwise specified, the numbering of each method step is only for the purpose of identifying each method step, and not to limit the arrangement order of each method or to limit the scope of the implementation of the present application. Changes or adjustments of the relative relationship, without substantial technical content changes, can also be considered as the scope of implementation of the present application.

[0070] The raw materials and instruments used in the examples are not specifically limited in source, and can be purchased in the market or prepared according to the conventional methods well known to those skilled in the art. The MXene nanosheet used in the present application is produced by Jinan Sanchuan New Material Technology Co., Ltd. x Powder product.

[0071] The tensile strength test method of the present application is the tensile test of metal thin strip. The tensile test is implemented according to the national standard GB / T3076-1982 "Metal Thin Plate (Strip) Tensile Test Method". The tensile sample size is prepared according to the national standard GB / T6397-1986 "Metal Tensile Test Sample". The thickness of the tensile sample is 50 μm.

[0072] The hardness test method is a static nanoindentation method based on atomic force microscopy.

[0073] Extrusion in the present invention refers to the deformation of metal through the die opening under the action of strong force, usually using an extruder, and the source of strong force can be hydraulic, compressed air or mechanical pressure. Rolling refers to the deformation of metal under the action of pressure and shear force through rotating rollers, which can also be called rolling, rolling or calendering.

[0074] The present invention provides a metal lithium composite material and a processing method thereof. The processing method of the metal lithium composite material comprises the following steps: (1) melt mixing, mixing molten metal lithium or lithium alloy with MXene to obtain a mixed lithium slurry; (2) solidification step, cooling and solidifying the mixed lithium slurry to obtain a composite lithium ingot; (3) forming step, forming the composite lithium ingot by extrusion and / or rolling to provide shear force, and processing to obtain a composite lithium sheet or a composite lithium foil, which can be used as a negative electrode of a lithium metal battery. Figure 1 As shown in the figure, MXene is dispersed in molten metal lithium or lithium alloy in the melt mixing step, and MXene is uniformly and randomly dispersed in the mixed lithium slurry and the composite lithium ingot. We unexpectedly found that the shear force generated by the extrusion and / or rolling processing method in the forming step can form a directional layered arrangement structure of the randomly dispersed MXene nanosheets in the metal lithium or lithium alloy matrix.

[0075] The present invention also found that the shear force generated by the extrusion and / or rolling processing method in the forming step can also induce the metal lithium in the composite lithium ingot to expose more lithium Li(110) crystal surface. For the lithium metal negative electrode, since the migration barrier of Li atoms on the Li(110) crystal surface is lower than that on the Li(200) crystal surface, it is easier to diffuse and migrate horizontally on the Li(110) surface, resulting in planar dendrite-free lithium deposition, and it is generally believed that the Li(110) crystal surface is less likely to grow dendrites than other crystal surfaces. Therefore, the present invention also provides a method for inducing high (110) crystal surface metal lithium.

[0076] The present invention found that the directional layered arrangement of MXene nanosheets can also become the internal skeleton of the metal lithium composite material, improving the mechanical properties of the metal lithium composite material, including hardness and tensile strength, solving the technical problem that metal lithium is easy to break and deform during extrusion or rolling due to its soft texture and low hardness, and is difficult to process. In particular, by the processing method of the present invention, an ultra-thin metal lithium with a thickness of ≤20 microns and continuous, uniform thickness and self-supporting can be obtained.

[0077] We also found that the extruded / rolled metal lithium composite material shows excellent air stability, which is due to the corrosion resistance of MXene nanosheets themselves, combined with the directional layered arrangement of MXene nanosheets in metal lithium or lithium alloy, which can effectively prevent the corrosion of corrosive substances (such as air, electrolyte) on lithium metal, prevent the reaction of the surface metal lithium with corrosive substances, and the layered arrangement of nanosheets can be used as a physical barrier to increase the structural tortuosity of the metal lithium composite material, prolong the path required for the corrosive substance to corrode the metal lithium, thereby effectively prolonging the time for the metal lithium to be oxidized, or preventing most of the metal lithium from being oxidized. That is, the metal lithium composite material of the present application shows excellent air stability, and when it is used in industrial production, it can be placed in the air environment for a long time, solving the problem of harsh environmental requirements due to the flammable and explosive nature of metal lithium during production and manufacturing.

[0078] Example 1

[0079] The present embodiment provides a metal lithium composite material and a processing method thereof, wherein the processing method steps include:

[0080] 1) Melt mixing: In a glove box under argon atmosphere, place the metal lithium block or metal lithium alloy in a crucible and heat to melt into a liquid state; add a certain amount of MXene to the liquid metal lithium and stir to mix evenly; since MXene has a lithium affinity, the mixed lithium slurry after adding MXene changes to a viscous gel state; preferably, the mass ratio of MXene added to the mass of metal lithium or lithium and lithium alloy is between (0.1-50):100;

[0081] 2) Cooling and solidification step: naturally cool the mixed lithium slurry in step 1 to room temperature to obtain a composite lithium ingot; in the embodiments of the present application, the composite lithium ingot is cylindrical (the internal shape of the container crucible);

[0082] In other embodiments, in order to facilitate subsequent processing and molding, the composite lithium slurry is filled into a mold of other shapes (such as a square block, a sheet), to obtain a composite lithium ingot of different shapes;

[0083] 3) Processing and molding: In a dry room environment, place the composite lithium ingot obtained in step 2 into an extrusion and / or rolling equipment, and extrude and / or roll the composite metal lithium column into a metal lithium composite material. The extrusion or rolling process can provide a large shear force to cause directional deformation of the composite lithium ingot.

[0084] In the processing method of the present application, the melting and cooling and solidification of metal lithium and alloy are in an inert gas environment, and the extrusion and rolling process is in a dry room environment to control the moisture in the environment. In specific embodiments of the present application, the melting and cooling and solidification of metal lithium and alloy are in an argon environment, and the extrusion and rolling process is in a dry room environment with a dew point below -50°C, and other tests are carried out in a conventional air environment.

[0085] In a specific embodiment, the composite lithium ingot is put into an extrusion device to obtain a composite lithium sheet with a thickness of 100 microns to 1 millimeter; the obtained composite lithium sheet is covered with a film (PET release film) on both sides, and is rolled several times to obtain a composite lithium foil or ultra-thin metal lithium with different thicknesses (1 to 100 microns). The directional layered arrangement structure of MXene can be optimized by multiple rolling, and the mechanical properties of the composite lithium foil or ultra-thin metal lithium can be adjusted. In some preferred embodiments, the composite lithium foil or ultra-thin metal lithium is heated and softened before rolling; in some embodiments, the temperature of heating and softening is 50-120°C.

[0086] The film is then removed, and the shape of the composite lithium sheet, composite lithium foil or ultra-thin metal lithium is adjusted, such as by shearing or stamping. In a specific embodiment, we found that the composite lithium foil of the present application can be easily peeled off from the PET film, which is due to the parallel arrangement of the MXene nanosheets in the directional layered arrangement and the film surface, reducing the adhesion between the metal lithium and the film, which is very advantageous for obtaining a continuous and uniform thickness composite lithium foil, especially suitable for industrial continuous production and large size composite lithium foil. In contrast, when the mixed lithium paste is coated on the substrate to prepare the metal lithium foil, due to the soft texture of the metal lithium and the high adhesion to the substrate, it is difficult to separate completely, and it is difficult to obtain a continuous and uniform thickness metal lithium foil, especially when preparing a large size metal lithium foil, which is more prominent.

[0087] The present embodiment also provides a metal lithium composite film, which comprises a film-composite lithium foil-film structure. Since the composite lithium foil has a protective film layer on both sides, the obtained film-composite lithium foil-film composite layer has excellent stability and is suitable for long-term storage, avoiding the problem of flammable and explosive unsafe storage of metal lithium. When used, the film layer can be torn off and removed. In the present embodiment, the film layer is a PET release film with a thickness of 0.1 mm, which serves to assist film rolling. Other materials or thicknesses of materials can also be selected, such as polyimide (PI), polypropylene (PP) or polyethylene (PE).

[0088] In some embodiments, the film layer can also be selected from high polymer and / or metal materials, and a single-sided or double-sided metal composite film with the film layer can be obtained in the rolling process; in a specific embodiment, a metal lithium composite film with a single side of copper foil is obtained after rolling the composite lithium foil with a copper foil in the rolling process; preferably, the thickness of the composite lithium foil is 1-100 microns, and the thickness of the copper foil is 1-10 microns; in a preferred embodiment, the thickness of the composite lithium foil is 10-20 microns, and the thickness of the copper foil is 3-5 microns. In other embodiments, the material of the film layer arranged on one side or both sides of the composite lithium foil can also be a high polymer material such as PET, PI, PP, PE, etc.; or other types of metal materials such as aluminum foil, nickel foil, stainless steel foil, titanium foil, etc.; or a composite foil of high polymer and metal, such as a composite foil formed by PET and metal copper foil.

[0089] It should be noted that extrusion processing has the advantage of rapid prototyping, but is limited by existing extrusion equipment and processes. In particular, compared with pure lithium, the mechanical properties and hardness of the MXene composite lithium metal are increased after reinforcement, which greatly increases the pressure required in the extrusion process, and the requirements for the extrusion forming mold and process are higher, so it is difficult to obtain a composite lithium foil with a thickness of ≤100 μm by one-time extrusion. In order to obtain a lithium foil with a thinner thickness, we further reduce the thickness by rolling the extruded composite lithium sheet several times. Therefore, the more preferred embodiment of the present application is to first extrude and then roll, which can obtain a lithium foil with a thickness of ≤100 μm (especially a lithium foil with a thickness of ≤50 μm, or even ≤20 μm), and the production is more efficient.

[0090] Example 2

[0091] The present embodiment provides a specific metal lithium composite material and a processing method thereof, wherein MXene is Ti3C2T x nanosheets containing fluorine functional groups, and the processing method steps include:

[0092] In an argon atmosphere glove box, 10 g of metal lithium block is heated to 200°C, and the metal lithium block is melted into a liquid state. 1 g of Ti3C2T x nanosheets is added to the liquid lithium, and the mixing is continuously stirred until the Ti3C2T x nanosheets are uniformly dispersed in the liquid lithium to form a mixed lithium slurry; after the mixed lithium slurry is naturally cooled, a composite lithium ingot is obtained.

[0093] In a dry room (dew point below -50℃), the composite lithium ingot is put into an extrusion device, the extrusion head pressure and pushing speed are set to 50-150 tons and 1 mm / min respectively, after a composite lithium sheet with a thickness of 1 mm is obtained, the roll gap distance of the rolling device is adjusted to 50 μm under a pressure of 5 tons, then the composite lithium sheet is put into the rolling device to obtain an ultrathin composite lithium foil, the thickness of which is only 13 μm Figure 2 ), and the ultrathin composite lithium foil presents obvious metallic luster and good continuity and self-supporting property.

[0094] The surface of the obtained ultrathin composite lithium foil is characterized by scanning electron microscopy (SEM) Figure 3 ), it can be seen that the surface has obvious flaky coverage, and the flakes are MXene nanosheets. The ultrathin composite lithium foil is immersed in anhydrous ethanol to strip the metallic lithium, the metallic lithium slowly reacts and dissolves with ethanol, and the remaining material (MXene nanosheet layer) is characterized by cross-sectional SEM Figure 4 a and b), the directional layered arrangement structure of two-dimensional nanosheets can be clearly observed, indicating that the MXene nanosheets are transformed from a disordered state to an ordered directional layered arrangement during the extrusion process.

[0095] By adjusting the roll gap distance of the rolling device, composite lithium foils with different thicknesses (such as 1 μm to 1000 μm) can be obtained. In some specific embodiments of the present application, composite lithium foils with different thicknesses of 9 μm, 13 μm, 20 μm, 50 μm, 100 μm, 200 μm, and 500 μm are obtained. Figure 5 A cross-sectional SEM photo of the ultrathin composite lithium foil with a thickness of only 9 μm obtained after rolling (without stripping the metallic lithium) is given, and it can be seen that the ultrathin composite lithium foil has uniform thickness and smooth surface.

[0096] The composite lithium slurry is poured into a cylindrical mold, after cooling and solidification, it is taken out of the mold and cut into a comparative lithium foil with a thickness of about 50 μm for comparative testing to illustrate the technical effects of extrusion or rolling.

[0097] In order to verify the air stability of the composite lithium foil of the present application, the obtained composite lithium foil (50 μm), the test wafer punched from the comparative lithium foil and the metallic lithium sheet (thickness about 500 μm, purchased from the market) are placed in an air environment at room temperature (about 25℃), and the surface changes at different times are observed; the test results are as follows Figure 6As shown, it can be seen that the metal lithium sheet is initially silver-white metal luster, and the surface is completely changed to black (lithium nitride) after 60 min of air exposure. The metal lithium sheet is easily oxidized and nitrided in air; compared with the lithium foil, it gradually changes from silver-white metal luster to black and then to grayish white after 15 min, indicating the nitridation and oxidation process of the metal lithium sheet; and the composite lithium foil of the application is still silver-white metal luster after being placed in air for 360 min (6 h), which shows the best air stability.

[0098] Figure 7 The comparative diagram of the XRD spectra of the metal lithium sheet, the comparative lithium foil and the composite lithium foil (50 μm) of the application is given, and it can be seen that the metal lithium sheet shows a sharp high-intensity diffraction peak at about 52° (200) crystal face, and a significantly low-intensity diffraction peak at about 36° (110) crystal face, indicating that the pure metal lithium shows low (110) crystal face and high (200) crystal face; while the composite lithium foil of the application is just the opposite, showing a low-intensity diffraction peak at (200) crystal face and a high-intensity diffraction peak at (110) crystal face. In comparison, the intensity of (200) and (110) crystal faces of the comparative lithium foil is in the middle. It shows that the addition of MXene nanosheets and extrusion / rolling treatment can adjust the crystal face orientation of metal lithium, and then obtain a metal lithium composite material with high (110) crystal face.

[0099] Since the migration barrier of lithium atoms on the lithium (110) crystal face is lower than that on the lithium (200) plane, it is easy to diffuse and migrate horizontally on the lithium (110) surface, resulting in planar dendrite-free lithium deposition. Therefore, it is generally believed that the lithium (110) surface is less likely to grow dendrites than other crystal surfaces. It is known that controlling lithium electrode crystallization with preferred (110) crystal face orientation is also an effective strategy to realize highly reversible lithium metal batteries (LMBs), but there is a lack of simple control method. (See article: Directing (110) Oriented Lithium Deposition through High-flux Solid Electrolyte Interphase for Dendrite-free Lithium Metal Batteries, Angewandte Chemie International Edition, 2023 (62) 42, https: / / doi.org / 10.1002 / anie.202309622). The application provides a simple and easy method for controlling high (110) crystal face metal lithium, and the metal lithium composite material with high (110) crystal face is used for lithium metal battery electrode, which is beneficial to produce planar dendrite-free lithium.

[0100] By adjusting the roll gap distance of the rolling equipment, composite lithium foils with different thicknesses can be obtained, Figure 8 A comparison chart of XRD spectra of composite lithium foils with thicknesses of 50, 100, 200, and 500 μm is given. It can be seen that, as the thickness of the composite lithium foil thins, the intensity of the (110) crystal plane of metallic lithium gradually increases, and the intensity ratio of the (110) crystal plane to the (200) crystal plane of metallic lithium (I (110) :I (200) ) increases from 2.695 when the thickness is 500 μm to 7.646 when the thickness is 50 μm. The reason for this phenomenon can be explained as follows: During the extrusion and rolling process, a large shear force is generated, which promotes the directional layered arrangement of MXene nanosheets. The thinner the composite lithium foil, the greater the shear force it receives. At the same time, the horizontally arranged MXene induces (110) crystal plane slip of lithium under the action of pressure, and a high (110) crystal plane composite lithium foil is obtained. The intensity of the (002) crystal plane of MXene decreases as the thickness thins.

[0101] In order to evaluate the effect of the method of the present application on the mechanical properties of metallic lithium, hardness tests were performed on metallic lithium sheets, composite lithium foils, and comparative lithium foils. The results are shown in Figure 9 It can be seen that the hardness of the composite lithium foil of the present application (342.3) is significantly higher than that of the metallic lithium foil (10.37) and the comparative lithium foil (29.7). This is also the reason why the composite lithium foil obtained by the method of the present application exhibits excellent self-supporting performance.

[0102] Example 3

[0103] In this example, the content of MXene was adjusted using a method similar to that of Example 2, and the air stability of composite lithium foils with different MXene contents was tested. The air stability is represented by the time for which the sample can maintain metallic luster at room temperature in an air environment. The longer the time, the better the air stability. The results are shown in the following table:

[0104] Table 1. Air stability test results of composite lithium foils with different MXene contents

[0105]

[0106] It can be seen that the air stability is related to the content of MXene in metallic lithium. A higher content of MXene forms a multi-layer structure that can more effectively provide protection. Preferably, the mass ratio of MXene to metallic lithium is greater than 1:10, more preferably greater than 1:20; and even more preferably greater than 1:10. In some embodiments, the mass ratio of MXene to metallic lithium is between (0.1-0.5):1.

[0107] Tensile tests were conducted on composite lithium foils with different MXene contents, control lithium foils, and metallic lithium foils (pure lithium, 50 μm thick). The stress-strain curves are shown below. Figure 10 As shown, sample 3, with an MXene to lithium metal mass ratio of 1:10, exhibits the highest tensile strength (3.22 MPa), significantly superior to the control lithium foil (1.63 MPa) and lithium metal foil (1.05 MPa). Samples 1 and 2, with the addition of small amounts of MXene, also show a significant increase in tensile strength. This demonstrates that the oriented layered structure of MXene nanosheets formed after shear extrusion significantly improves the mechanical properties of the composite lithium foil, resulting in better tensile strength.

[0108] Example 4

[0109] This embodiment provides a lithium metal battery containing the composite lithium foil of the present invention, that is, the application of the lithium metal composite material of the present invention in a battery. The composite lithium foil (approximately 20 μm thick) obtained by the method in Example 2 was placed in room temperature air for 24 hours, and then assembled into a coin cell lithium metal battery (CR2032). The charge and discharge performance at different current densities was tested. The composite lithium foil not exposed to air was used as a control sample.

[0110] The specific assembly method of the battery includes: in a glove box with a water and oxygen content of less than 0.1 ppm, composite lithium foil stamped into small discs (16 mm in diameter) is used as the negative electrode, and placed in the order of negative electrode, separator, and positive electrode. Electrolyte (LB-092) is then added and the battery is sealed. The positive electrode material is lithium iron phosphate. Following standard laboratory testing methods, the positive electrode material, binder, and conductive carbon black are mixed in an 8:1:1 ratio, heated to a slurry state using NMP solvent, coated onto aluminum foil, dried, and then stamped. A comparative negative electrode battery was assembled using the same method.

[0111] The electrochemical performance testing conditions were as follows: using a Blue Battery testing instrument, the assembled full cells were subjected to charge-discharge cycles of 2-3.8V at room temperature, following the charge-discharge rate sequence of 0.2C, 0.5C, 1C, 2C, 3C, 5C, 2C. The electrochemical test results are as follows: Figure 11 As shown, the electrochemical performance of the negative electrode after 24 hours of exposure to air is very similar to that of the unexposed control negative electrode. This demonstrates that the composite lithium foil of the present invention exhibits excellent air stability, significantly reducing the stringent environmental requirements during the production of lithium metal batteries.

[0112] MXenes are a family of two-dimensional materials with similar structures and properties, and their general chemical formula can be represented as M. n+1 X n T xwherein M is selected from one or more of Ti, V, Mo, Nb, Ta, W, Zr, Y; X is selected from one or more of carbon, nitrogen or boron, 1≤n≤4, T x The meaning is that the surface contains functional groups. The specific embodiments in the present application can also select MXene nanosheets composed of other elements, such as Nb3C2T x , V2CT x , Ti2CT x , Ti4C3T x , Ti3CNT x , VNbCT x , Ta4C3T x , etc. These MXene nanosheets have similar two-dimensional sheet structures and surface functional groups, and are used to composite with metal lithium or lithium alloy to produce the same or similar effects as the method of the present application, and are all included in the technical solutions of the present application. Considering the ease of raw material preparation and cost, the preferred MXene is Ti3C2T x .

[0113] In the present application, the composite lithium sheet or lithium foil is used for the negative sheet of the lithium battery, and the MXene nanosheet containing fluorine (F) functional groups is preferred. The surface of the ultra-thin metal lithium electrode prepared also has a native LiF layer, which is derived from the reaction product of the F-containing functional groups on the surface of the MXene and the metal lithium. As a lithium metal battery electrode, the LiF can become part of the solid electrolyte interface on the surface of the lithium anode during the cycling of the battery, and can guide and homogenize the lithium ion flow, so that the lithium metal deposition is more uniform, and the problem of lithium metal dendrite growth is alleviated.

[0114] In some embodiments, the components of the composite lithium of the present application can also be a composite of metal lithium alloy and MXene, such as lithium-magnesium alloy, lithium-aluminum alloy, etc. Through the processing method of the present application, the MXene nanosheet produces a directional layered arrangement structure in the lithium alloy, or obtains the same or similar technical effects as the present application, which are all within the technical solutions of the present application.

[0115] In other embodiments, the metal lithium composite material of the present application can also be used in the fields of medicine, petrochemicals, fine chemicals as a catalyst, in lithium batteries as an electrode material or a lithium supplement material, and in the metallurgical field for the manufacture of light alloys.

[0116] Example 5

[0117] The present embodiment provides a metal lithium composite material production system for the processing method of the present application to prepare MXene / metal lithium composite material, such as Figure 12As shown, it includes: an inert gas system 10, a melting device 20, a cooling and solidification device 30, an extrusion device 40, a rolling device 50, and a slitting device 60; wherein, the inert gas system 10 includes an inert gas environment chamber 11, the melting device 20 and the cooling and solidification device 30 are disposed in the inert gas environment chamber 11, the inert gas environment chamber 11 is used to provide an inert gas environment (such as argon) and control the water and oxygen content to avoid the reaction of molten lithium metal or lithium alloy with water and oxygen; the melting device 20 includes a heater 21, a container 22 and a stirring device 23, used to heat and melt lithium metal or lithium alloy, and uniformly mix it with MXene powder to obtain a mixed lithium liquid 100; the cooling and solidification device 30 includes at least one mold 31, used to cool and solidify the mixed lithium liquid 100 to obtain a composite lithium ingot.

[0118] In this embodiment, the mixed lithium liquid 100 is added to the mold and cooled and solidified. After demolding, multiple small block-shaped composite lithium ingots are obtained. These composite lithium ingots are placed in the extrusion device 40 and extruded to obtain composite lithium sheets 200. The composite lithium sheets 200 are then passed through the rolling device 50 and rolled several times to obtain composite lithium foil 300. The composite lithium foil is then shaped into a predetermined shape by the slitting device 60.

[0119] Example 6

[0120] This embodiment provides another production system for lithium metal composite materials. The inert gas system 10, melting device 20, and cooling and solidification device 30 are the same as in Embodiment 5, except that, as shown in the example... Figure 13 As shown, it also includes a coating device 70, used to provide a coating layer to one or both sides of the composite lithium sheet 200 before rolling. In this embodiment, it is double-sided coating to facilitate rolling and obtain a composite lithium foil with a smooth surface. After rolling, a coating-lithium foil-coating composite layer 500 is obtained. After the coating is removed by the demolding device 80, a composite lithium foil 300 is obtained. The composite lithium foil 300 is then wound up by the winding device 90 to form a roll. The coating is preferably a polymer material. In this embodiment, PET film is selected, as the composite lithium foil of the present invention can be easily peeled off from the PET film.

[0121] In another embodiment, the decoating device 80 may be omitted, resulting in a film-lithium foil-film composite layer 500. This film-lithium foil-film composite layer 500 is then slit or wound. Because both sides are protected by a film layer, the film-lithium foil-film composite layer 500 is suitable for long-term storage, improving the safety of the composite lithium foil. When the composite lithium foil product is needed, the film can simply be peeled off.

[0122] In another embodiment, the composite lithium sheet 200 can be directly rolled to obtain the composite lithium foil 300 without the coating device 70.

[0123] In another embodiment, the extruded composite metal sheet 200 is directly fed into the slitting device 60 to form a predetermined shape, or into the winding device 70.

[0124] In another embodiment, the composite lithium ingot can also be directly rolled several times to form a composite lithium sheet or a composite lithium foil, and then fed into the slitting device 60 to form a predetermined shape, or into the winding device 70.

[0125] Since the MXene material has a lithium affinity, it can be easily mixed and dispersed in molten lithium metal. In the preparation of the lithium alloy and MXene composite lithium alloy foil, the content of lithium in the alloy is between 0.1 and 99.9 wt.%; the mass ratio of the MXene to the lithium metal in the alloy is between (0.01-1):1; preferably, between (0.1-0.5):1.

[0126] Example 7

[0127] This embodiment provides a composite lithium-magnesium alloy foil and a method for preparing the same. Similar to Example 2, the difference is that after the molten lithium-magnesium alloy liquid is mixed with the MXene nanosheet in an argon atmosphere, the composite lithium-magnesium alloy ingot is formed after cooling and solidification, and then extrusion and / or rolling processing is performed.

[0128] More specific implementation steps include: under an argon environment, 10 g of metallic lithium block is heated to 300°C, and the metallic lithium block is melted into a liquid state, 1 g of Ti3C2T x The nanosheet is dispersed in the molten metallic lithium liquid, and a metal stirrer is used to stir for 10 min to make it uniformly dispersed, and then 2 g of small pieces of metallic magnesium are added, and the heating temperature is increased to 650°C to gradually melt the metallic magnesium pieces to form a mixed lithium-magnesium slurry; the mixed magnesium-lithium slurry is then cooled and solidified into a composite lithium-magnesium ingot, which is then extruded and / or rolled into a sheet or a foil.

[0129] Similarly, in another embodiment, the metallic magnesium pieces are replaced with metallic aluminum pieces to obtain a composite lithium-aluminum alloy foil.

[0130] Similarly, in another embodiment, the Ti3C2T x Nanosheet can also be replaced with other types of MXene, such as Nb2CT x , to obtain a composite lithium-magnesium alloy foil or a composite lithium-aluminum alloy foil.

[0131] Example 8

[0132] This embodiment provides a magnesium-lithium alloy and MXene composite lithium-magnesium alloy foil and a method for preparing the same. Similar to Example 2, the difference is that after the molten magnesium-lithium alloy liquid is mixed with the MXene nanosheet in an argon atmosphere, the composite lithium-magnesium alloy ingot is formed after cooling and solidification, and then extrusion and / or rolling processing is performed.

[0133] More specifically, the implementation steps include: heating 10 g of lithium metal blocks to 250 °C under an argon environment, melting the lithium metal blocks into a liquid state, adding 1 g of Ti3C2T x The nanosheets are dispersed in the molten lithium metal liquid and stirred for 10 min using a metal stirrer to make them uniformly dispersed, and then cooled to room temperature to obtain a composite lithium metal;

[0134] The magnesium metal blocks are then heated to 650-680 °C until they melt into a magnesium metal liquid, and the above-mentioned amount of composite lithium metal is added to the magnesium metal liquid and stirred to obtain a composite magnesium-lithium alloy liquid, which is then cooled to room temperature to obtain a composite magnesium-lithium alloy. Preferably, the mass content of lithium metal in the composite magnesium-lithium alloy is between 1-20%, and the mass content of MXene is between 0.1-10%. After further extrusion and / or rolling treatment of the obtained composite magnesium-lithium alloy, a composite magnesium-lithium alloy foil is obtained.

[0135] In a specific embodiment, the mass content of lithium metal in the composite magnesium-lithium alloy is 16%, the mass content of MXene is 8%, and the mass content of magnesium metal is 76%.

[0136] Example 9

[0137] This embodiment provides a composite aluminum-lithium foil of aluminum-lithium metal alloy and MXene and a preparation method thereof. Similar to Example 8, the difference is that the magnesium metal is replaced by aluminum metal, and the alloying elements are one or more of lithium, magnesium, and copper. The specific preparation method includes: heating 10 g of lithium metal blocks to 250 °C under an argon environment, melting the lithium metal blocks into a liquid state, adding a certain amount of Ti3C2T x The nanosheets are dispersed in the molten lithium metal liquid and stirred for 10 min using a metal stirrer to make them uniformly dispersed, and then cooled to room temperature to obtain a composite lithium metal;

[0138] The aluminum metal blocks are then heated to 650-680 °C until they melt into an aluminum metal liquid, and the above-mentioned amount of composite lithium metal, magnesium flakes, and copper powder is added to the aluminum metal liquid and stirred to obtain a composite aluminum-lithium alloy liquid, which is then cooled to room temperature to obtain a composite aluminum-lithium alloy. After several times of rolling, a composite aluminum-lithium alloy foil is obtained.

[0139] The composition of the obtained composite aluminum-lithium alloy foil sample (thickness of 100 μm) and the corresponding tensile property test (such as Figure 14 ) maximum tensile strength (UTS) are shown in the following table:

[0140] Table 2. Composition of aluminum foil and composite aluminum-lithium foil samples and their corresponding maximum tensile strength

[0141]

[0142] It can be seen that the maximum tensile strength of the metal aluminum is greatly improved after adding lithium, and the sample (A-1L-0.5MX) containing 0.5% MXene shows the maximum tensile strength. The relationship between the metal alloy composition and the mechanical properties is complex, and the specific mechanism is not clear.

[0143] Corrosion resistance test: the composite aluminum lithium foil sample is immersed in a commercial aluminum alloy metallographic etchant (diluted nitric acid alcohol) for 20s and 60s, and then the surface state is observed by SEM, Figure 15 and 16 The surface SEM photos of samples AL and A-1L-0.5MX are shown respectively. It can be seen that the surface of the sample AL without MXene shows obvious grain boundaries after etching for 20s, indicating that the metal is etched along the grain boundaries. After etching for 60s, the grain boundaries become more obvious and the etching is further deepened. For the sample A-1L-0.5MX, the surface is still flat after etching for 20s, and no obvious grain boundaries are observed. After etching for 60s, fine lines appear on the surface, which are different from the grain boundaries of sample AL. This may be related to the coverage of MXene nanosheets on the surface. It can be seen that the composite alloy foil containing MXene obtained by the processing method of the present application can effectively improve the corrosion resistance of the material.

[0144] Example 10

[0145] This embodiment provides a composite lead lithium foil of metal lead lithium alloy and MXene and a preparation method thereof. Similar to example 9, the difference is that the metal aluminum is replaced by metal lead, and the alloy element is metal lithium or magnesium. The specific preparation method comprises: under an argon environment, heating 10g of metal lithium block to 250℃, melting the metal lithium block into a liquid state, dispersing a certain amount of Ti3C2T x nanosheets in the molten metal lithium liquid, and stirring uniformly for 10min using a metal stirrer, cooling to room temperature to obtain a composite metal lithium;

[0146] Then, the metal lead is heated to 380℃ to melt into a metal lead liquid, and then a certain amount of composite metal lithium is added into the molten lead liquid according to the formula, and the composite metal lead liquid is obtained by stirring and dispersing uniformly, and then cooled to room temperature to obtain a composite metal lead. The composite metal lead is rolled by a rolling equipment, and a composite lead foil is obtained after several times of rolling.

[0147] In this embodiment, a composite lead foil with a thickness of 1mm is obtained and its tensile properties are tested. The comparative samples are metal lead foil (Pb) and lead lithium alloy foil (commercial lead alloy Pb alloy) obtained by the same method without adding MXene. As shown in Table 3 and Figure 17

[0148] Table 3. Different components of lead foil and composite lead lithium foil samples and their corresponding maximum tensile strength ​

[0149]

[0150] From the above table, it can be seen that the tensile strength of the lead lithium tin aluminum alloy (Pb alloy) formed by adding alloying elements to the lead alloy is significantly improved. The tensile strength of the lead lithium alloy sample with a small amount of MXene (0.1%~0.2%) is also significantly improved compared with the pure lead sample. However, the tensile strength of the pure lead sample with MXene (Pb MX0.2) is significantly less than that of the lead lithium alloy sample with MXene, which may be related to the uniform dispersion of MXene in the lead lithium alloy promoted by the metal lithium component in the lead alloy. In particular, the maximum tensile strength of the lead lithium alloy with 0.1~0.2% MXene when the content of metal lithium is 0.3% exceeds that of the commercial lead alloy (Pb alloy), indicating that the addition of MXene to the lead lithium alloy can effectively improve the mechanical properties of the material.

[0151] The foregoing description of specific exemplary embodiments of the application is intended to be illustrative only and is not intended to limit the scope of the application. Changes and modifications can be made by those skilled in the art which fall within the scope of the application as defined by the appended claims. The specific exemplary embodiments were chosen and described in order to explain particular principles of the application and its practical application, and to enable others skilled in the art to understand the application for various embodiments and with various modifications as are suited to the particular use contemplated. The scope of the application is defined by the claims and their equivalents.

Claims

1. A metal lithium composite, characterized by, The metal composite comprises a substrate of metal lithium or lithium alloy material and MXene nanosheets; the MXene nanosheets are arranged in an oriented layered structure in the substrate.

2. The metal lithium composite of claim 1, wherein, The thickness of the metal lithium composite is ≤1000 μm; preferably, the thickness is ≤500 μm; more preferably, the thickness is ≤200 μm; more preferably, the thickness is ≤100 μm; more preferably, the thickness is ≤50 μm; more preferably, the thickness is ≤20 μm; more preferably, the thickness is ≤10 μm. And / or, the surface of the metal lithium composite is covered with MXene nanosheets; or, the surface of the metal lithium composite shows MXene nanosheet coverage after metal corrosion.

3. The lithium metal composite of claim 1, wherein, The chemical formula of the MXene is represented as: M n+ 1X n T x , wherein M represents one or more of transition metal elements Ti, V, Mo, Nb, Ta, W, Zr, Y, X represents one or more of carbon, nitrogen or boron elements, T x represents a functional group containing; 1≤n≤4; preferably, the functional group contains a fluorine element; most preferably, M in the MXene is Ti element, X is carbon element, T x contains a fluorine element; And / or, the alloying elements in the lithium alloy are selected from one or more of Na, Mg, Al, Zn, Sn, V, In, Ag, Au, B, Si, Ge; And / or, the lithium content in the lithium alloy is between 0.1 wt.% and 99.9 wt.%; And / or, the mass ratio of MXene to metal lithium in the lithium alloy is between (0.01-1):1; preferably, between (0.1-0.5):

1.

4. The metal lithium composite of any one of claims 1 to 3, wherein, The metal lithium composite forms the oriented layered structure by the following method: Mixing molten metal lithium or lithium alloy with MXene nanosheets to obtain a mixed lithium slurry; after cooling and solidification of the mixed lithium slurry, a composite lithium ingot is obtained; the composite lithium ingot is formed into a sheet or foil shape by extrusion and / or rolling; during the extrusion and / or rolling process, the MXene nanosheets form the oriented layered structure in the substrate.

5. The lithium metal composite of claim 1, wherein the lithium metal composite has a lithium utilization of at least 80% after 1000 cycles. The oriented layered structure is characterized by scanning electron microscopy testing; more preferably, the metal lithium in the metal lithium composite is peeled off before scanning electron microscopy testing; And / or, the scanning electron microscopy testing of the metal lithium composite shows that the surface is covered with two-dimensional nanosheets; And / or, the X-ray diffraction (XRD) testing of the metal lithium composite shows the (002) diffraction peak of MXene, the (110) crystal plane and (200) crystal plane diffraction peaks of metal lithium; the intensity ratio of the (110) crystal plane and (200) crystal plane diffraction peaks of metal lithium is greater than 2.6; preferably, the ratio is greater than 4.2, more preferably, the ratio is greater than 5.2; more preferably, the ratio is greater than 7.

6.

6. A method for processing a metal lithium composite material, characterized by, The processing method comprises: mixing molten metal lithium or lithium alloy with MXene nanosheets to obtain a mixed lithium slurry; after cooling and solidification of the mixed lithium slurry, a composite lithium ingot is obtained; the composite lithium ingot is formed by extrusion and / or rolling.

7. The method of claim 6, wherein the step of processing is performed by a computer. The thickness of the metal lithium composite is ≤1000 μm; preferably, the thickness is ≤500 μm; more preferably, the thickness is ≤200 μm; more preferably, the thickness is ≤100 μm; more preferably, the thickness is ≤50 μm; more preferably, the thickness is ≤20 μm; more preferably, the thickness is ≤10 μm.

8. The method of processing according to claim 6 or 7, wherein, The composite lithium ingot is first extruded into a composite lithium sheet, and then the composite lithium sheet is rolled several times to obtain a composite lithium foil with a reduced thickness; preferably, the thickness of the composite lithium foil is ≤100 μm; more preferably, the thickness is ≤50 μm; further preferably, the thickness is ≤20 μm; further preferably, the thickness is ≤10 μm.

9. The method of claim 8, wherein the processing is performed by a computer. In the rolling process, a film layer is arranged on one side or both sides of the composite lithium sheet. Preferably, the film layer is made of a high polymer material and / or a metal material. More preferably, the high polymer material is polyethylene terephthalate (PET), polyimide (PI), polypropylene (PP), or polyethylene (PE); and the metal material is a copper foil, an aluminum foil, a stainless steel foil, a nickel foil, or a titanium foil.

10. The method of claim 6, wherein the step of processing is characterized by, The X-ray diffraction (XRD) characterization of the metal lithium composite material has a (002) diffraction peak of MXene, a (110) crystal face diffraction peak of metal lithium, and a (200) crystal face diffraction peak of metal lithium; the intensity ratio of the (110) crystal face diffraction peak and the (200) crystal face diffraction peak of metal lithium is greater than 2.6; preferably, the ratio is greater than 4.2, further preferably, the ratio is greater than 5.2; more preferably, the ratio is greater than 7.

6. And / or, the MXene nanosheet presents a directional layered arrangement structure in the metal lithium composite material. And / or, the surface of the metal lithium composite material is covered with MXene nanosheets; or, the surface of the metal lithium composite material shows MXene nanosheet coverage after metal corrosion. and / or, the chemical formula of the MXene is represented as: M n+1 X n T x wherein M represents one or more of transition metal elements Ti, V, Mo, Nb, Ta, W, Zr, Y, X represents one or more of carbon, nitrogen or boron elements, T x represents containing a functional group; 1≤n≤4; preferably, the functional group contains a fluorine element; most preferably, M in the MXene is Ti element, X is carbon element, T x contains a fluorine element. And / or, the alloying element in the lithium alloy is selected from one or more of Na, Mg, Al, Zn, Sn, V, In, Ag, Au, B, Si, and Ge; And / or, the lithium content in the lithium alloy is between 0.1 wt.% and 99.9 wt.%; And / or, the mass ratio of MXene to metal lithium or metal lithium in the alloy is between (0.01-1):1; preferably, between (0.1-0.5):1; And / or, when the metal lithium or lithium alloy is 100 parts, the addition amount of MXene is 0.1-50 parts; preferably, the addition amount of MXene is 0.1-30 parts; more preferably, the addition amount of MXene is 0.1-20 parts; further preferably, the addition amount of MXene is 0.1-10 parts; most preferably, the addition amount of MXene is 5-10 parts.

11. A metal lithium composite as claimed in any one of claims 1 to 5, or a metal lithium composite obtained by the process as claimed in any one of claims 6 to 10, characterized in that The tensile strength of the metal lithium composite material is more than 2 times, preferably more than 3 times, of the tensile strength of the same size of metal lithium; And / or, the hardness of the metal lithium composite material is more than 10 times, preferably more than 20 times, more preferably more than 30 times, of the hardness of the same size of metal lithium; And / or, the metal lithium composite material maintains metallic luster in air for more than 1 h; preferably, more than 2 h; further preferably, more than 2 h; more preferably, more than 3 h; more preferably, more than 4 h; more preferably, more than 5 h; more preferably, more than 6 h.

12. Use of the metal lithium composite material according to any one of claims 1 to 5, 11, or the metal lithium composite material obtained by the processing method according to any one of claims 6 to 10, as an electrode material or a lithium supplement material in a lithium battery, or for manufacturing a lightweight alloy.

13. A production system of a metal lithium composite material, characterized by, The production system comprises: an inert gas system, a melting device, a cooling and solidifying device, an extruding device, and / or a rolling device; the inert gas system comprises an inert gas environment cabin, and the melting device and the cooling and solidifying device are arranged in the inert gas environment cabin; the melting device comprises a heater, a container, and a stirring device, and is used for heating and melting metal lithium or a lithium alloy, mixing the metal lithium or the lithium alloy with MXene powder, and obtaining a mixed lithium liquid; the cooling and solidifying device comprises a mold, and is used for cooling and solidifying the mixed lithium liquid to obtain a composite lithium ingot; the extruding device is used for extruding the composite lithium ingot into a composite lithium sheet or a composite lithium foil; the rolling device is used for rolling the composite lithium ingot into a composite lithium sheet or a composite lithium foil, or is used for rolling the extruded composite lithium sheet into a composite lithium foil.

14. The production system of claim 13, wherein, The production system further comprises: a slitting device, which is used for slitting the composite lithium sheet or the composite lithium foil into a predetermined shape; and / or a winding device, which is used for winding the composite lithium sheet or the composite lithium foil; and / or a film coating device, which is used for providing a film layer on one side or both sides of the composite lithium sheet before the rolling step; or the film coating device and a film removing device, which is used for removing the film layer after the rolling step; 15. A metal lithium composite film, characterized by, and / or a dry room system, which is used for controlling the moisture in the environment, and the extruding device and / or the rolling device are in the environment of the dry room system. The metal lithium composite film comprises: the metal lithium composite material according to any one of claims 1 to 5, 11, or the metal lithium composite material obtained by the processing method according to any one of claims 6 to 10; one side or both sides of the metal lithium composite material are provided with a film layer; preferably, the material of the film layer is a high polymer material and / or a metal material; more preferably, the high polymer material is polyethylene terephthalate (PET), polyimide (PI), polypropylene (PP), or polyethylene (PE); and the metal material is a copper foil, a nickel foil, a stainless steel foil, an aluminum foil, or a titanium foil.

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