Metal affinity curled structure and preparation method thereof, metal-based composite material, electrode and application

Abstract

The invention discloses a metal affinity curled structure and a preparation method thereof, a metal-based composite material, an electrode and application, the curled structure is formed by curling atomic layers formed by transition metal carbide or carbonitride, and adjacent transition metal atomic layers are bonded through metal atoms to form a non-Van der Waals structure. The curled structure is prepared by a pulse Joule heating technology, and has high thermal stability and excellent metal affinity. The composite material serves as a reinforcing phase to be compounded with molten metal, the interface energy can be remarkably reduced, and the high-strength metal-based composite material is prepared. When the composite material is used as a negative electrode of a metal battery, the composite material can promote uniform deposition of metal and inhibit growth of dendrites, and shows low nucleation overpotential and long cycle life.

Description

Technical Field

[0001] This invention belongs to the field of new materials and new energy, and specifically relates to metal affinity non-van der Waals coil structures and their preparation methods, metal matrix composites, electrodes and applications. Background Technology

[0002] Metal batteries, especially those using lithium, magnesium, and other metals as anodes, are considered an important development direction for next-generation high-energy-density energy storage devices due to their high theoretical specific capacity and energy density. Among these, constructing a metal hybrid anode, which combines an active metal with a functional enhancement phase, is one of the effective strategies for suppressing dendrite growth and improving electrode mechanical strength and cycle stability.

[0003] However, the practical preparation and application of this type of electrode material still face a series of severe challenges. The primary bottleneck lies in the inherent physical and chemical incompatibility between the molten metal and the reinforcing phase. Most molten metals have high surface tension, while commonly used carbon-based or ceramic reinforcing materials have low surface energy, resulting in poor interfacial wettability. This makes it difficult for the reinforcing phase to be uniformly dispersed in the metal matrix, easily leading to agglomeration and phase separation, and preventing the formation of a stable three-dimensional reinforcing network. Therefore, the prepared composite materials often have limited mechanical reinforcement effects, and poor interfacial contact increases ion transport impedance.

[0004] Secondly, the insufficient thermal stability of the reinforcing phase material itself severely limits the preparation process window and application range of composite materials. Existing melt composite methods are usually limited to low-melting-point metal systems (such as lithium, gallium, indium and their alloys). For practical metals with higher melting points, such as magnesium and aluminum, the processing temperature is high, and many nanomaterials are prone to structural collapse, oxidation or amorphization at high temperatures (e.g., MXene materials exceeding 250-300℃), leading to performance failure. This makes it extremely difficult to prepare high-performance, high-melting-point metal composite materials through simple blending.

[0005] Furthermore, even if physical mixing can be achieved, the weak interfacial bonding force between the enhanced phase and the metal matrix (such as van der Waals forces or simple mechanical interlocking) is difficult to effectively suppress the volume change of the electrode and promote the uniform deposition of ions during cycling, ultimately affecting the long-cycle performance of the battery. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention designs a metal affinity non-van der Waals coil structure based on two-dimensional (2D) transition metal carbides (MXenes). This structure can withstand high-temperature molten metal environments and also interact chemically with the metal matrix, solving the interfacial incompatibility problem and achieving efficient dispersion and strong interfacial bonding of the reinforcing phase. This provides a key material foundation for the preparation of next-generation high-performance metal battery anodes and lightweight, high-strength composite materials.

[0007] The first aspect of the present invention provides a metal affinity coil structure having a one-dimensional coil morphology with a hollow structure, formed by the coiling of atomic layers composed of transition metal carbides or carbonitrides, and the adjacent transition metal atomic layers are bonded by metal to form a non-van der Waals structure.

[0008] In some embodiments, the general formula of the aforementioned transition metal carbides or carbonitrides is AM. n+1 X n T x Where A is a bonding metal selected from at least one of Al, Sn, Ge, and Ga; M is a transition metal selected from at least one of V, Ti, Nb, Ta, Zr, Mo, W, and Cr; X is carbon and / or nitrogen; and T is a bonded metal. x This represents the surface end groups contained; n is between 1 and 4.

[0009] In some implementations, the above general formula is A-M2XT x .

[0010] In some embodiments, A is Al, and M is selected from at least one of V, Ti, Nb, and Ta.

[0011] In some embodiments, the radius of the hollow structure is 10 nanometers to 50 nanometers.

[0012] In some embodiments, the aforementioned metal-affinity coiled structure exhibits thermal stability, with a mass loss of no more than 1 wt.% at 800°C.

[0013] In some embodiments, the electrical conductivity of the aforementioned metal-affinity coiled structure is not less than 500 S / cm.

[0014] In some embodiments, the aforementioned metal-affinity coil structure contains oxygen functional groups; that is, T in the general formula x It represents a functional group containing oxygen (O).

[0015] A second aspect of the present invention provides a method for preparing the above-mentioned metal affinity coil structure, comprising the steps of:

[0016] A coiled MXene and a metal source are provided; the coiled MXene and the metal source are mixed and heat-treated in an inert atmosphere using pulsed Joule heating to form metal bonds between the metal atoms and the adjacent atomic layers of the coiled MXene, thereby obtaining the metal affinity coiled structure.

[0017] In some embodiments, after the above heat treatment, the method further includes a step of treating with an acid solution to remove unreacted metal sources.

[0018] In some embodiments, the energizing time of the pulse Joule heating is 0.1-2.0 seconds, and the de-energizing time is 0.3-5.0 seconds.

[0019] In some embodiments, the peak temperature of the pulsed Joule heating is 1100K to 1300K.

[0020] In some embodiments, the power of the pulsed Joule heating is set between 186 and 258 W.

[0021] In some embodiments, the number of cycles of the above-mentioned pulsed Joule heating is 1 to 10.

[0022] In some embodiments, the mass ratio of the curled MXene to the aluminum source is 5:1 to 1:3.

[0023] A third aspect of the present invention provides a metal matrix composite material comprising a metal matrix and the aforementioned metal affinity coil structure dispersed in the metal matrix, wherein the metal affinity coil structure is bonded to the metal matrix through interfacial chemical bonding and capillary forces.

[0024] In some embodiments, the content of the aforementioned metal-affinity coiled structure in the composite material is from 0.1 wt.% to 1.0 wt.%; preferably, it is between 0.2 wt.% and 0.6 wt.%.

[0025] In some embodiments, the metal matrix is ​​selected from one metal or an alloy of multiple metals with a melting point ≤800°C.

[0026] In some embodiments, the metal matrix is ​​selected from magnesium, lithium, gallium, aluminum, indium, tin, lead, sodium, zinc, aluminum or alloys thereof (containing one or more of the aforementioned metals).

[0027] In some embodiments, the hollow structure of the aforementioned metal affinity coiled structure is filled with the metal matrix.

[0028] In some embodiments, the above-mentioned interfacial chemical bonding is an M'-OM chemical bond, where M' represents a metal atom of the metal matrix, O represents an oxygen atom, and M represents a transition metal atom. M originates from the transition metal atom in the transition metal carbide or carbonitride in the above-mentioned metal affinity coil structure, and O originates from the oxygen functional group therein.

[0029] In some embodiments, the tensile strength of the above-mentioned metal matrix composite material is increased by more than 60% compared with that of the metal matrix material; preferably, it is increased by more than 100%, more preferably, it is increased by more than 120%.

[0030] In some embodiments, when the metal matrix is ​​magnesium or a magnesium alloy, the tensile strength of the metal matrix composite material is not less than 120 MPa; preferably, not less than 200 MPa.

[0031] In some embodiments, when the metal matrix is ​​lithium, the tensile strength of the metal matrix composite material is not less than 1 MPa; preferably, it is not less than 1.5 MPa.

[0032] The fourth aspect of the present invention provides a method for preparing the above-mentioned metal matrix composite material, the steps of which include: mixing the above-mentioned metal affinity coil structure with a molten metal matrix under an inert atmosphere, utilizing the metal affinity and capillary force of the coil structure to uniformly disperse it in the molten metal and form an interfacial bond, and then cooling and solidifying it.

[0033] In some embodiments, the aforementioned metal-affinity coiled structure is prepared as a porous preform before mixing and then bonded to the preform via spontaneous infiltration of a molten metal matrix.

[0034] In some embodiments, the above preparation method further includes a step of rolling the obtained metal matrix composite material to obtain a metal composite foil.

[0035] In some embodiments, the thickness of the aforementioned metal composite foil is between 5 and 500 micrometers.

[0036] The fifth aspect of the present invention provides a metal composite foil, characterized in that it comprises: a metal matrix; and the aforementioned metal affinity coiled structure uniformly dispersed in the metal matrix, wherein the metal affinity coiled structure has a one-dimensional coiled morphology with a hollow structure, is formed by coiling atomic layers composed of transition metal carbides or carbonitrides, and its adjacent atomic layers are bonded by metal to form a non-van der Waals structure.

[0037] In some embodiments, the thickness of the aforementioned metal composite foil is no more than 500 micrometers.

[0038] In some embodiments, the thickness of the aforementioned metal composite foil is from 5 micrometers to 200 micrometers.

[0039] In some embodiments, the content of the aforementioned metal affinity coil structure in the metal composite foil is from 0.1 wt.% to 1.0 wt.%; preferably, it is between 0.2 wt.% and 0.6 wt.%.

[0040] In some embodiments, the metal matrix is ​​selected from magnesium, lithium, aluminum, zinc, gallium or alloys thereof (containing one or more of these metals).

[0041] In some embodiments, the metal matrix is ​​magnesium or a magnesium-aluminum alloy.

[0042] In some embodiments, the general formula of the above-mentioned metal affinity coil structure is A-M2CT. x A is a bonding metal selected from at least one of Al, Sn, Ge, and Ga; M is a transition metal selected from at least one of V, Ti, Nb, and Ta.

[0043] In some embodiments, the hollow structure of the above-described curled structure is filled with the metal matrix.

[0044] In some embodiments, the tensile strength of the aforementioned metal composite foil is increased by more than 60% compared to that of the metal base material; preferably, it is increased by more than 100%, and more preferably, it is increased by more than 120%.

[0045] In some embodiments, when the metal matrix is ​​magnesium or a magnesium alloy, the tensile strength of the metal composite foil is not less than 120 MPa; preferably, it is not less than 200 MPa.

[0046] In some embodiments, when the metal matrix is ​​lithium, the tensile strength of the metal composite foil is not less than 1 MPa; preferably, it is not less than 1.5 MPa.

[0047] In some embodiments, the aforementioned metal composite foil is obtained by repeated rolling and / or polishing of a metal matrix composite material.

[0048] A sixth aspect of the present invention provides an electrode comprising the metal affinity coiled structure described above; or, the metal matrix composite material described above; or, the metal composite foil described above.

[0049] In some embodiments, the electrode described above is the negative electrode of the battery.

[0050] In some embodiments, the electrode is the negative electrode of a magnesium metal battery or a lithium metal battery.

[0051] A sixth aspect of the present invention is an electrochemical device comprising the electrodes described above.

[0052] In some embodiments, the electrochemical device described above is a battery.

[0053] The seventh aspect of the present invention provides the use of the above-described metal affinity coil structure in reducing the surface tension of molten metal and / or improving the mechanical strength of metal.

[0054] The eighth aspect of the present invention provides the application of the above-mentioned metal affinity curled structure, or the above-mentioned metal matrix composite material, or the above-mentioned metal composite foil in aerospace, flexible electronics, transportation, biomedicine, high-end electronic packaging, electromagnetic shielding, flexible conductors, sensors, lightweight and high-strength structural components and other fields.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0056] (1) Significantly improved thermal stability and electrical conductivity: The non-van der Waals coil structure constructed by metal bonding in this invention exhibits extremely high thermal stability, maintaining structural stability at temperatures up to 800°C (with a mass loss of less than 1%), far superior to traditional MXene materials. Simultaneously, this structure displays high electrical conductivity (e.g., Al-V2CT). x The coiled structure has an electrical conductivity of up to 526.3 S / cm, which ensures rapid electron transport.

[0057] (2) Material exhibits metal affinity: The non-van der Waals coil structure of this invention, with its abundant surface dangling bonds and nanoscale hollow structure, can form strong chemical bonds (such as Mg-OV bonds) with molten metals (such as Li, Ga, Mg and their alloys) and generate strong capillary forces. This unique metal affinity effectively overcomes the inherent high surface tension problem between molten metal and reinforcing phase, and significantly reduces the interfacial energy of the composite system.

[0058] (3) High-strength metal matrix composite material preparation achieved: Thanks to the aforementioned metal affinity, the coiled structure of this invention can be uniformly dispersed in various molten metals and form strong interfacial bonds, thereby preparing metal matrix composite materials with significantly improved mechanical properties. For example, magnesium foil (Mg / Al-V2CT) incorporating this coiled structure. x Its tensile strength is as high as 204 MPa, which is more than twice that of pure magnesium foil (about 91 MPa), demonstrating a reinforcing effect.

[0059] (4) A high-performance, long-life metal battery anode was obtained: When the metal matrix composite material of the present invention is applied to the metal battery anode, its stable three-dimensional network structure and good interfacial bonding effectively promote the uniform deposition of metal ions and suppress dendrite growth. For example, based on Mg / Al-V2CT... x The magnesium metal full cell assembled with the negative electrode can still retain a capacity of about 90.0% after 500 cycles at 1C rate, and exhibits a lower nucleation overpotential (252mV) and diffusion resistance, which significantly improves the cycle life and rate performance of the battery.

[0060] (5) It provides a universal and scalable material platform: The pulsed Joule heating synthesis method involved in this invention is fast, efficient, and has good scalability. Using this method, materials including Al-V2CT have been successfully prepared. x Al-Ti2CT x The coiled structures of various transition metal carbides, including [list of examples], demonstrate the broad applicability of this strategy, providing a universal platform for designing and preparing a series of high-performance metal affinity materials. Attached Figure Description

[0061] Figure 1 The pulsed Joule heating technique used in Embodiment 1 of this invention is used to synthesize the coiled structure (Al-M2CT). x The diagram shows red, blue, brown, yellow, and gray spheres representing M, Al, C, O, and H atoms, respectively.

[0062] Figure 2 The non-van der Waals Al-V2CT in Embodiment 1 of the present invention x Fourier transform infrared (FTIR) spectra of coiled structures, and coiled V2CT x Compared to 870cm -1 The VF key and 1395cm -1 The decrease in the intensity of the characteristic vibrational peak of the OH bond indicates that some of the surface functional groups (-F and -OH) have been removed.

[0063] Figure 3 In Embodiment 1 of the present invention, a) non-van der Waals Al-V2CT x X-ray diffraction (XRD) patterns of the coiled structure. b, c) Non-van der Waals Al-V2CT x Transmission electron microscopy (TEM) images (b) and cross-sectional TEM images (c) of the coiled structure. d) Non-van der Waals Al-V2CT x High-resolution transmission electron microscopy (HRTEM) image of the corresponding cross-section of the curled structure.

[0064] Figure 4 In Embodiment 1 of the present invention, a) in a tube furnace, V2CT is rolled up. x a) XRD pattern of the product obtained by reacting aluminum powder with aluminum powder at 1260K for 5 min. b) SEM and EDS mapping images of the obtained product, showing that the product has a multi-particle morphology.

[0065] Figure 5 In Embodiment 1 of the present invention, a) non-van der Waals Al-V2CT x HRTEM images and corresponding FFT maps of the coiled structure (inset). b) Non-van der Waals Al-V2CT x EDS mapping image of the coiled structure shows uniform distribution of V, Al, and C elements.

[0066] Figure 6 The non-van der Waals Al-V2CT in Embodiment 1 of the present invention x Chemical valence states of coiled structures. a, b) Non-van der Waals Al-V2CT x(T is predominantly -O) Full X-ray photoelectron spectroscopy (XPS) spectrum (a) and corresponding high-resolution Al 2p spectrum (b) of the coiled structure, showing non-van der Waals Al-V2CT. x The coiled structure contains a characteristic peak of V-Al bonds, and this peak is observed in the coiled V2CT. x (T is absent in -F, -OH, and -O) c)Al-V2CT x Normalized VK-edge X-ray absorption near-edge structure (XANES) spectrum of the coiled structure. d, e) Non-van der Waals Al-V2CT x curled structure k 3 Weighted extended X-ray absorption fine structure (EXAFS) Fourier transform spectrum (d) and wavelet transform plot (e).

[0067] Figure 7 The non-van der Waals Al-V2CT in Embodiment 1 of the present invention x Thermal stability of the coiled structure. a) Al-V2CT under argon atmosphere. x Thermogravimetric analysis (TG) curves of the coiled structure show the relationship with the coiled V2CT. x Compared to its counterpart, its high-temperature stability (800℃) is enhanced. b) Al-V2CT x Comparison of the TG curves of the coiled structure and V2AlC.

[0068] Figure 8 Al-V2CT filled with Mg in Example 1 of this invention x TEM images of the coiled structure and corresponding elemental mapping images show a uniform distribution of Mg, V, Al, and C elements.

[0069] Figure 9 The Mg / Al-V2CT in Example 1 of this invention x The high-resolution O1s XPS spectrum shows two peaks at 530.5 eV and 532.1 eV, corresponding to Mg-OV and Mg-O bonds, respectively.

[0070] Figure 10 For non-van der Waals Al-Ti2CT in Embodiment 2 of this invention (a, c, e, g) x (a) Al-(Nb) 0.4 V 0.6 )2CT x (c) Al-(Ta 0.4 V 0.6 )2CT x (e) and Al-(Ti 0.5 V 0.5 )2CT x (g) XRD patterns of the coiled structure. (b, d, f, h) Non-van der Waals Al-Ti2CTx (b) Al-(Nb) 0.4 V 0.6 )2CT x (d) Al-(Ta 0.4 V 0.6 )2CT x (f) and Al-(Ti) 0.5 V 0.5 )2CT x (h) The corresponding TEM images of the coiled structure all show a one-dimensional nanotube morphology.

[0071] Figure 11 In Example 3 of this invention, a) molten Ga, Li, Mg, Ga-In, and Mg-Al and non-van der Waals Al-V2CT x Optical images of the combined coiled structures show the effects of non-van der Waals Al-V2CT. x The surface tension decreases after the addition of molten metal to the coiled structure. b)Mg / Al-V2CT x The tensile stress-strain curve shows a mechanical tensile strength of approximately 204 MPa, which is Mg / V2CT. x (Approximately 94 MPa) and twice that of pure Mg (approximately 95 MPa). c)Li / Al-V2CT x Mg / Al-V2CT x and Mg-Al / Al-V2CT x The tensile strength histogram of the foil shows that its tensile strength is enhanced compared to pure metals and their alloys.

[0072] Figure 12 The optical image shown is of the comparative sample block V2AlC mixed with molten gallium (a), gallium-indium alloy (b), lithium (c), magnesium-lithium alloy (d), and magnesium-aluminum alloy (e) in Example 3 of the present invention. It shows obvious phase separation in the molten metal.

[0073] Figure 13 In Example 3 of the present invention, a) contains 0.2, 0.4, 0.6, and 0.8 wt.% Al-V2CT. x a) Tensile stress-strain curves of rolled magnesium composite foils. b) Tensile strength histograms of these magnesium composite foils.

[0074] Figure 14 For Mg / Al-V2CT at different magnifications in Examples 3 and 4 of this invention (a) and (b) x SEM images of the fracture surface of the composite material show a dimple-like fracture morphology, indicating that magnesium and non-van der Waals Al-V2CT x The curled structures form an interlocking three-dimensional network structure.

[0075] Figure 15In Example 3 of this invention, a) Mg-Al / Al-V2CT x The tensile stress-strain curve shows a mechanical tensile strength of approximately 200 MPa, higher than that of magnesium-aluminum alloys (approximately 120 MPa). b) Li / Al-V2CT x The tensile stress-strain curve shows that its mechanical tensile strength is approximately 1.80 MPa, which is twice that of pure lithium (approximately 0.89 MPa).

[0076] Figure 16 The Mg / Al-V2CT in Example 4 of this invention x CV curve of asymmetric negative electrode cell at a scan rate of 5 mV / s.

[0077] Figure 17 The Mg / Al-V2CT in the symmetric cell of Example 4 of this invention x Electrochemical performance of the negative electrode. a) Mg / Al-V2CT x The negative electrode is at 0.5 mA / cm. 2 Constant current discharge curves at current density. b) Mg / Al-V2CT x 1–20 mA / cm 2 The rate performance at different current densities shows good rate performance. c)Mg / Al-V2CT x The negative electrode is at 1 mA / cm 2 1mAh / cm 2 The constant current cycling performance under certain conditions is excellent, with a cycle life of up to 950 hours. (df)Mg / Al-V2CT x (d) Mg / V2CT x (e) and two-dimensional intensity color plots of the DRT curves of the pure Mg(f) negative electrode symmetric cells, showing the Mg / Al-V2CT curves. x Negative electrode symmetrical cells have lower diffusion resistance (R0). d gj)Mg / Al-V2CT x The negative electrode is at 3mA / cm 2 SEM images of the Mg deposition process after 60 min of electroplating show uniform Mg growth behavior, while the pure Mg anode exhibits an uneven Mg growth morphology.

[0078] Figure 18 The Mg / V2CT is the control sample (a) and (b) in Example 4 of this invention. x The negative electrode is at 3mA / cm 2 SEM images of the magnesium deposition process at current densities of 0 (a) and 60 min (b), showing the Mg / V2CT ratio. x The magnesium deposition morphology on the negative electrode surface is uneven.

[0079] Figure 19In Example 4 of this invention, ac)Mg / Al-V2CT x (a) Mg / V2CT x (b) and pure Mg(c) anode at 3 mA / cm 2 In-situ optical images of electroplating at current densities of 0, 5, 20, and 60 min. Mg / Al-V2CT x The negative electrode surface is macroscopically smooth, with no magnesium dendrite growth; while under the same conditions, Mg / V2CT x Uneven magnesium deposition and magnesium dendrite growth occur on the surface of pure Mg anode.

[0080] Figure 20 Mg / Al-V2CT in the full cell of Example 4 x Electrochemical performance of the negative electrode. a) Mg / Al-V2CT x Wetting behavior of the negative electrode with APC electrolyte. b) Mg / Al-V2CT x The EIS curve of the negative electrode full cell shows a lower charge transfer impedance (Ri). ct c, d) Mg / Al-V2CT x The rate performance (c) and corresponding charge-discharge curves (d) of the negative electrode at different current densities from 0.1 to 2C demonstrate excellent rate performance. (e) Mg / Al-V2CT x Long-term cycling performance of the negative electrode.

[0081] Figure 21 The lithium iron phosphate (LiFePO4) cathode and Li / Al-V2CT in Example 5 of this invention x The long-term cycling performance of the full cell assembled with the negative electrode is as follows: after 100 cycles at a 1.0C rate, the capacity retention is about 95%, which is higher than that of the pure Li negative electrode full cell (about 83%).

[0082] Figure 22 Li / Al-V2CT in Embodiment 5 of the present invention x And pure Li anode at 1mA / cm 2 SEM images of electrodeposition morphology after 1, 3 and 5 hours of electroplating at current density.

[0083] Figure 23 Li / Al-V2CT in Embodiment 5 of the present invention x The EIS curve of the negative electrode symmetrical cell shows its charge transfer impedance (Ri). ct It is smaller than a pure Li negative electrode symmetrical cell.

[0084] Figure 24This is a schematic diagram of the metal affinity non-van der Waals coiled structure of the present invention. a) Schematic diagram of the dispersion behavior of non-van der Waals bulk materials and coiled structures in molten metal, showing that the non-van der Waals coiled structure with abundant surface dangling bonds and nanoscale hollow structures has good metal affinity. b) Capillary forces (P) in molten Mg c The relationship between the radius (r) and the non-van der Waals coil structure with a radius of 10–50 nm has a strong capillary force of 8.6–43.0 MPa, while the capillary force of the non-van der Waals bulk material is close to 0 MPa. Detailed Implementation

[0085] The technical solution of the present invention is illustrated below through specific embodiments. It should be understood that the one or more steps mentioned in the present invention do not preclude the existence of other methods and steps before or after the combined steps, or that other methods and steps may be inserted between these explicitly mentioned steps. It should also be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Unless otherwise stated, the numbering of each method step is only for the purpose of identifying each method step, and not for limiting the order of each method or limiting the scope of the present invention. Changes or adjustments to their relative relationships, without substantial changes to the technical content, can also be considered as within the scope of the present invention.

[0086] The raw materials and instruments used in the examples are not subject to any specific restrictions on their source; they can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0087] Example 1

[0088] This embodiment provides a metal affinity coiled structure and its preparation method, the steps of which include:

[0089] First, provide the curled MXene and metal source (A);

[0090] Next, the coiled MXene is mixed with a metal source and heat-treated in an inert atmosphere using pulsed Joule heating to form metal bonds (MAM) between the metal atoms (A) and the adjacent transition metal (M) atomic layers of the coiled MXene, resulting in a metal affinity coiled structure.

[0091] The preferred chemical formula of this invention is M2XT. x The coiled MXene, where M represents a transition metal element (such as Ti, V, Nb, Ta, etc.), X is carbon and / or nitrogen, and T is... x This indicates the presence of surface end groups (such as -F, -O, etc.). Due to the fewer atomic layers, these coiled MXenes are easier to prepare into coiled hollow structures with uniform tube diameter.

[0092] The following uses aluminum powder (Al) as the metal source and rolled MXene as the rolled V2CT.x Preparation of coiled Al-V2CT x Taking an example, the technical features of the present invention are illustrated, and the implementation steps include:

[0093] 1.1 Curved V2CT x Preparation of precursors

[0094] First, a coiled MXene precursor was synthesized via a stiffness-mediated coiling method. The steps included: selectively etching the Al component in the MAX phase V2AlC to obtain multilayer V2CT. x Then, the multilayer V2CT x The coiled V2CT was obtained by stirring / sonicating in a tetrabutylphosphine hydroxide (TBPH) solution. x .

[0095] The specific implementation steps are as follows:

[0096] (1) 4.0 g of V2AlC powder was uniformly added to an autoclave containing 60 mL of 12 mol / L hydrochloric acid and 4 g of sodium fluoride (NaF). The autoclave was placed in an oven and heat-treated at 95 °C for 4 days. After cooling to room temperature, the resulting multilayer V2CT was obtained. x Wash repeatedly with deionized water until the pH value is about 6, and then dry under vacuum at 60°C for 12 hours.

[0097] (2) 0.5g of multilayer V2CT x Add 25 ml of 25 wt.% TBPH solution and stir at 600 rpm for 30 minutes. Then, centrifuge at 10000 rpm, wash the mixture repeatedly with deionized water, and collect the precipitate. Next, redisperse the precipitate in 80 ml of deionized water and sonicate for 1 hour. Centrifuge the suspension further at 2500 rpm for 5 minutes and collect the supernatant. Finally, freeze-dry the supernatant for 24 hours to obtain the curled V2CT. x , where T represents -OH, -F, and -O.

[0098] 1.2 Non-van der Waals coil structure (Al-V2CT) x Synthesis of

[0099] like Figure 1 As shown, the target product was synthesized via a topological reaction between coiled MXene and a metal source using pulsed Joule heating technology. The steps included: mixing the prepared coiled MXene with a metal source in a specific ratio; then placing the mixture on a conductive substrate and performing pulsed heating cycles under an inert atmosphere using a programmable power supply. Optionally, after the reaction, the resulting product was treated with acid to remove excess metal source components, followed by repeated washing with deionized water. After drying, a non-van der Waals coiled structure A-M2XT was obtained.x .

[0100] In some embodiments, the mass ratio of coiled MXene to metal source is 5:1 to 1:3, the energizing time of the pulse Joule is 0.1-2.0 seconds, the de-energizing time is 0.3-5.0 seconds, the peak heating temperature is 1100K to 1300K, and the number of pulse Joule heating cycles is 1 to 10; more preferably, the energizing time of the pulse Joule is 0.1-0.5 seconds, the de-energizing time is 0.3-2.0 seconds, and the number of cycles is 2 to 5.

[0101] In some specific embodiments, the mass ratio of curled MXene to metal source is 1:1.2 to 1:2, the pulse Joule heating device is set with a voltage of 18V, a current of 14 to 19A, a heating power-on time of 0.3 seconds, a power-off time of 1.0 second, and a cycle count of 3 times.

[0102] In other embodiments, the metal source can also be replaced with tin powder (Sn), germanium powder (Ge), or gallium powder (Ga), which can form MAM metal bonds to obtain the curled structure of the present invention.

[0103] In this embodiment, the prepared curled V2CT x The aluminum metal powder was uniformly mixed at a mass ratio of 1:1.5. The mixture was then placed on a carbon paper substrate and subjected to pulse heating (0.3 seconds on, 1.0 second off) to approximately 1260 K under an argon atmosphere using a programmable power supply, followed by quenching. This process was repeated three times. After the reaction, the resulting product was treated with 2 mol / L hydrochloric acid solution for 6 hours to remove excess aluminum, followed by repeated washing with deionized water. Finally, the sample was dried under vacuum at 70 °C for 6 hours to obtain the non-van der Waals coiled Al-V2CT structure. x .

[0104] In this embodiment, the curled V2CT x A non-van der Waals coil structure was synthesized through a topological reaction with aluminum (Al) metal, and the reaction equation is as follows:

[0105] V2CT x (T represents -F, -OH, -O) + Al → Al-V2CT x (T is -O) + H2O 气体 +HF 气体

[0106] Comparison sample: curled V2CT x The aluminum powder was placed in a tube furnace. Under an argon atmosphere, it was heated at 1260K for 5 minutes, and then cooled to room temperature to obtain the control sample product.

[0107] 1.3 Structural Characterization

[0108] To clarify the structural characteristics and formation mechanism of the product, we conducted a systematic characterization analysis of the synthesized material.

[0109] 1.3.1 Results and Morphological Characterization

[0110] By FTIR spectroscopy ( Figure 2 This confirms that during pulsed Joule heating, the coiled V2CT... x Some of the surface end groups (-OH and -F) were effectively removed. Simultaneously, molten aluminum spontaneously infiltrated and interacted with the rolled V2CT. x Adjacent transition metal atomic layers bond together to form aluminum-bonded V2CT. x Curved structure (denoted as Al-V2CT) x Its surface end groups T are mainly oxygen end groups, and the structural model is as follows: Figure 1 As shown.

[0111] XRD pattern ( Figure 3 a) The product exhibits a series of diffraction peaks at 13.2°, 26.6°, 35.4°, 41.1°, 55.4°, and 63.6°. These peak positions correspond to the (002), (004), (100), (103), (106), and (110) crystal planes of the non-van der Waals layered MAX phase V2AlC (PDF#29-0101), indicating that the obtained product has a crystal structure similar to that of the non-van der Waals MAX phase. TEM image ( Figure 3 (b, c) further revealed that the product has a distinct one-dimensional nanotube hollow structure with a diameter ranging from 20 to 100 nm. This is consistent with the particulate morphology of the comparative sample synthesized in a tube furnace under the same conditions. Figure 4 This contrasts sharply with the previous image, highlighting the unique advantages of pulsed Joule heating technology. HRTEM image ( Figure 3 d) The layered crystal arrangement was directly observed to be a sequence of alternating stacked V atomic layers and Al atomic layers, and the lattice fringe spacing was measured to be about 0.69 nm, which provides direct evidence for the formation of non-van der Waals structures.

[0112] In addition, HRTEM images and corresponding Fast Fourier Transform (FFT) maps ( Figure 5 a) This indicates that the coiled structure has single-crystal characteristics, with a spacing of approximately 0.25 nm, corresponding to the (110) crystal plane. Energy dispersive spectroscopy (EDS) mapping ( Figure 5 b) The results showed that V, Al and C elements were uniformly distributed in the rolled structure, confirming the successful introduction of aluminum and the uniformity of the structure.

[0113] 1.3.2 Chemical valence state and bonding analysis

[0114] XPS analysis showed that in Al-V2CT x The full spectrum of curled structures ( Figure 6 The characteristic peak of Al element appeared in a), and this peak was observed in the initial curl V2CT. x It does not exist in Al. High-resolution Al 2p spectrum ( Figure 6 b) Two clear peaks are observed at binding energies of 71.0 eV and 74.5 eV, attributed to Al-V and Al-O bonds respectively, directly demonstrating the successful construction of Al-V metallic bonds after the topological reaction. Furthermore, high-resolution V 2p spectroscopy indicates that, compared with the coiled V 2CT... x Compared to Al-V2CT x All V components (V 2+ V 3+ and V 4+ The peaks of VK edge XANES spectrum shift towards lower binding energies, suggesting a decrease in the valence state of V. This finding yielded the VK edge XANES spectrum. Figure 6 c) Further support for Al-V2CT x The absorption edge compared to the curled V2CT x The clear shift towards lower energies further confirms the decrease in the average valence state of V. To investigate the root cause of this decrease, we performed EXAFS and wavelet transform (WT) analyses. Figure 6 As shown in d and e, compared with the curled V2CT x Compared to Al-V2CT x At approximately 1.7 angstroms, it corresponds to VT. x The coordination strength was significantly weakened, mainly due to the partial removal of surface end groups during the topological reaction, a result corroborated by FTIR analysis.

[0115] 1.4 Performance Testing and Analysis

[0116] To comprehensively evaluate the prepared non-van der Waals Al-V2CT x We conducted systematic tests on the overall performance of the rolled structure, including its thermal stability, electrical conductivity, and, crucially, metal affinity.

[0117] 1.4.1 Thermal stability and electrical conductivity

[0118] Thermogravimetric analysis showed that Al-V2CT under an argon atmosphere x The coiled structure exhibits excellent thermal stability in the temperature range of 40–800℃, with a mass loss of only about 0.9 wt.% at 800℃. Figure 7 a) Its stability is comparable to that of the bulk V2AlC precursor. Figure 7 b). In stark contrast, the unmodified coiled V2CT xSignificant mass loss (approximately 19 wt.%) occurred within the temperature range of 100–310 °C, primarily due to the removal of surface end groups and structural collapse. Furthermore, four-probe testing revealed that non-van der Waals Al-V2CT... x The coiled structure exhibits a high electrical conductivity of 526.3 S / cm, significantly superior to bulk V2AlC (107.5 S / cm), laying the foundation for its application in constructing highly efficient conductive networks in composite materials.

[0119] 1.4.2 Metal affinity

[0120] Metal affinity is a core property of this material, which was verified by its interaction with molten metal. The procedure involved heating magnesium metal to a complete melt at 780°C in an argon-filled glove box. Subsequently, the prepared non-van der Waals Al-V2CT was... x A coiled structure was added to molten magnesium at a certain content (0.2–0.8 wt.%) and uniformly dispersed by mechanical stirring. The resulting product was labeled as Mg / Al-V2CT. x In this embodiment, non-van der Waals Al-V2CT is used. x The content of the curled structure is 0.4 wt.%.

[0121] TEM testing revealed that when Al-V2CT... x When the coiled structure is added to molten magnesium, it forms a typical metal-filled tubular morphology, with uniform distribution of Mg, V, Al, and C elements. Figure 8 This phenomenon is attributed to two key factors: first, Mg-OV chemical bonds are formed between the surface of the curled structure and the molten magnesium. Figure 9 Secondly, its nanoscale hollow structure generates strong capillary forces, and the two work together to achieve effective capture and bonding of molten metal, exhibiting unique metal affinity.

[0122] In this embodiment, a well-defined metal-affinity non-van der Waals coil structure was successfully prepared using pulsed Joule heating technology. This structure has a one-dimensional hollow morphology (diameter 20-100 nm), with adjacent transition metal atomic layers bonded by V-Al-V metal bonds, and exhibits extremely high thermal stability (0.9 wt.% mass loss) and high electrical conductivity (526.3 S / cm) at 800 °C.

[0123] Example 2

[0124] This embodiment presents a series of non-van der Waals coiled structures of transition metal carbides with different compositions to illustrate the universality of the pulse Joule heating topology synthesis method of the present invention.

[0125] The preparation of each coiled structure in this embodiment follows a similar process to that in Example 1, including: using the corresponding MAX phase as a precursor, obtaining coiled MXene through HCl / NaF etching and TBPH intercalation; subsequently mixing it with aluminum powder at a mass ratio of 1:1.5, and reacting it under an argon atmosphere using pulsed Joule heating (0.3 seconds on, 1.0 second off, 3 cycles); the product after the reaction is treated with 2 mol / L hydrochloric acid to remove unreacted aluminum, finally obtaining the target coiled structure. Specific synthesis conditions and key characterization results are shown in Table 1 below:

[0126] Table 1. Series Al-M2CT x Synthesis conditions and structural characteristics of coiled structures

[0127]

[0128] Note: Please refer to Tables 3 and 4 for pulse Joule heating settings.

[0129] This embodiment successfully prepared four transition metal carbide coiled structures with different metal compositions using essentially the same synthetic route. All products were confirmed by XRD to form novel layered structures (manifested as novel (002) diffraction peaks), and TEM confirmed that they all maintained a one-dimensional nanotube hollow morphology. This indicates that the pulsed Joule heating topological synthesis method provided by this invention has excellent universality and can be applied to a variety of MXene precursors ranging from single transition metals to complex solid solutions, providing a general and reliable preparation scheme for the construction of a metal affinity non-van der Waals coiled structure material platform.

[0130] Example 3

[0131] This embodiment demonstrates the application of metal affinity non-van der Waals coil structures as reinforcing phases in different metal matrices (M'), resulting in the preparation of various metal matrix composites, and systematically evaluating their enhancing effect on the mechanical properties of the composites. The implementation steps include: mixing a certain amount of non-van der Waals coil structures with molten metal under an inert atmosphere and mechanically stirring; after cooling, a metal matrix composite is obtained; and the corresponding metal composite foil is prepared through processes such as rolling, designated as M' / A-M2XT. x .

[0132] 3.1 Experimental Methods

[0133] This embodiment uses a non-van der Waals Al-V2CT. x Taking the coiled structure and magnesium-based composite material as examples, the reinforcement effect is explained in detail. Specific implementation steps include: in an argon-filled glove box, at 780°C, non-van der Waals Al-V2CT... xThe coiled structure was mixed with molten magnesium at different contents of 0.2, 0.4, 0.6, and 0.8 wt.% and mechanically stirred. After cooling to room temperature, the resulting alloy ingots were processed by rolling technology to prepare alloy foils of different thicknesses (e.g., 5–500 micrometers). Subsequently, the alloy foils were continuously polished using a series of sandpapers with different grits (800 mesh, 1200 mesh, 1500 mesh, 2000 mesh, and 3000 mesh) for subsequent characterization and mechanical tensile testing. The composite films with different contents were designated as Mg / 0.2 wt.% Al-V2CT. x Mg / 0.4wt.%Al-V2CT x Mg / 0.6wt.%Al-V2CT x and Mg / 0.8wt.%Al-V2CT x .

[0134] Based on the above general method, the following composite foils were successfully prepared by changing the metal substrate and adjusting the preparation temperature:

[0135] Li / Al-V2CT x : Mixed with molten lithium at 250°C under an inert atmosphere.

[0136] Ga / Al-V2CT x Mixed with molten gallium at 40°C.

[0137] Ga-In / Al-V2CT x Mix with molten Ga-In alloy at 50°C.

[0138] Mg-Al / Al-V2CT x Mixed with molten magnesium-aluminum alloy at 700℃.

[0139] Preparation of comparative samples: Under the same conditions, pure metal foil and composite material with bulk V2AlC as the reinforcing phase were prepared as comparative samples.

[0140] 3.2 Performance Testing

[0141] 3.2.1 Metal affinity and dispersibility

[0142] like Figure 11 As shown in a, all Al-V2CT x Macroscopically uniform foils were successfully prepared from the coiled composite system, demonstrating that this reinforcement exhibits excellent compatibility and dispersibility with various molten metals. In contrast, under the same conditions, bulk V₂AlC exhibits significant phase separation in molten metals due to its poor metal affinity. Figure 12 ).

[0143] 3.2.2 Mechanical Properties and Reinforcing Effects

[0144] The uniaxial tensile test results clearly show Al-V2CT x The significant strengthening effect brought about by the curled structure.

[0145] For Mg / Al-V2CT x The system, and tests on samples with different contents, showed that ( Figure 13 The results showed that 0.4 wt.% was the optimal addition amount, and the tensile strength of the 500-micron thick foil reached 204 MPa. Figure 11 b), approximately pure Mg foil (91 MPa) and Mg / V2CT x More than twice that of the foil (94MPa).

[0146] XPS analysis ( Figure 9 The detection of characteristic peaks of Mg-OV bonds confirmed the formation of strong interfacial chemical bonds between the reinforcing phase and the matrix. SEM observation... Figure 14 The fracture surface of the composite material exhibits a dimple-like morphology, indicating that an effective three-dimensional interlocking network is formed through strong interfacial bonding, which is the fundamental reason for the significant improvement in mechanical properties.

[0147] For other systems, in Li / Al-V2CT x and Mg-Al / Al-V2CT x Similar mechanical reinforcement effects have also been observed in other hybrid foils. Figure 11 c. Figure 15 The specific data is shown in Table 2 below, highlighting the universality of this reinforcement strategy.

[0148] Table 2. Comparison of Mechanical Properties of Different Material Systems

[0149] Material system Tensile strength (MPa) Compared with the corresponding pure metal or alloy Pure Mg foil 91 - <![CDATA[Mg / V2CT x Foil]]> 94 Slight improvement <![CDATA[Mg / Al-V2CT x Foil (0.4 wt.%))]> 204 An increase of approximately 124% Pure Li foil 0.89 - <![CDATA[Li / Al-V2CT x Foil]]> 1.80 An increase of approximately 102% Mg-Al alloy foil 120 - <![CDATA[Mg-Al / Al-V2CT x Foil]]> ～200 An increase of approximately 67%

[0150] This embodiment demonstrates that the non-van der Waals coil structure, due to its high-temperature stability and unique metal affinity, can serve as a versatile reinforcing phase. Through the aforementioned melt stirring and hot rolling process, it can be used to prepare various metal matrix composites. This structure effectively improves the dispersion of the reinforcing phase in the matrix and constructs a three-dimensional reinforcing network by forming strong interfacial chemical bonds (such as Mg-OV bonds), thereby significantly and universally enhancing the mechanical properties (such as tensile strength) of the composite material.

[0151] Example 4

[0152] This embodiment provides the application of the metal matrix composite material of the present invention as the negative electrode of a metal battery. Specifically, it uses non-van der Waals Al-V2CT. x Magnesium-based composites reinforced with curled structures (Mg / Al-V2CT) xTaking the electrochemical performance of magnesium metal batteries (MMBs) as an example, we can illustrate its advantages in practical battery applications.

[0153] 4.1 Experimental Procedure

[0154] 4.1.1 Battery Assembly

[0155] Negative electrode: Mg / 0.4wt.%Al-V2CT x Composite foil was used as the negative electrode in the experimental group; pure Mg foil and Mg / V2CT were used. x Composite foil was used as a control group.

[0156] Positive Electrode: Mo6S8 positive electrode material was synthesized via a molten salt method. The specific steps were as follows: 0.8g copper sulfide, 2g molybdenum disulfide, and 1.2g molybdenum powder were ball-milled and mixed uniformly for 24 hours. The mixture was then mixed with potassium chloride at a mass ratio of 1:4 and annealed at 1100℃ for 24 hours under an argon atmosphere to obtain Cu2Mo6S8. Subsequently, the mixture was treated with 6mol / L hydrochloric acid for 12 hours to remove copper, and after washing and drying, Mo6S8 positive electrode material was obtained. Mo6S8 powder, conductive agent Super P, and polyvinylidene fluoride (PVDF) were mixed at a mass ratio of 8:1:1 to form a slurry, which was then coated onto nickel foil with an active material loading of 2-3 mg / cm³. 2 .

[0157] Electrolyte and diaphragm: A 0.4 mol / L tetrahydrofuran solution of (PhMgCl)2-AlCl3 (APC) was used as the electrolyte, and glass fiber (Whatman) was used as the diaphragm. TM GF / D) is used as a diaphragm.

[0158] Battery assembly: All CR2032 button cells were assembled in a glove box filled with argon (H2O, O2 < 0.1ppm).

[0159] 4.2 Performance Testing

[0160] First, its electrochemical performance was evaluated in asymmetric / symmetric cells using cyclic voltammetry (CV). For example... Figure 16 As shown, with Mg / V2CT x Compared to pure Mg anodes, Mg / Al-V2CT x The negative electrode exhibits smaller voltage polarization and a higher current response, indicating enhanced redox activity of Mg deposition. Constant current discharge testing further demonstrates that the symmetric Mg / Al-V2CT... x The nucleation overpotential of the battery is 252mV. Figure 17 a) significantly lower than Mg / V2CT x The presence of (565mV) and pure Mg (572mV) negative electrodes confirmed their favorable Mg deposition kinetics.

[0161] Through 1~20mA / cm 2 The rate performance of the symmetrical cell was further evaluated by cycling it at a given current density. Figure 17 As shown in b, Mg / Al-V2CT x The battery is at 1mA / cm 2 It exhibits a low initial overpotential of 73 mV and maintains good kinetic performance even at high currents. Furthermore, at 1 mA / cm²... 2 and 1mAh / cm 2 Under these conditions, it achieved stable cycling for 950 hours with an overpotential of 126 mV. Figure 17 c) Superior to Mg / V2CT x (600h, 170mV) and pure Mg (326h, short circuit). Relaxation time distribution (DRT) analysis confirmed these results, indicating that Mg / Al-V2CT... x It exhibits lower diffusion resistance (R) throughout the entire cycle. d ()( Figure 17 (d and Figure S20), which is attributed to the coiled structure promoting Mg 2+ The transport of Mg was observed using SEM and in-situ optical microscopy. Figure 17 e and Figure 18 As shown, at 3mA / cm 2 After 60 minutes of electroplating, Mg / Al-V2CT x The negative electrode exhibits uniform Mg deposition, while the Mg / V2CT ratio is... x Irregular deposition occurs at the pure Mg anode. In-situ observation further confirms that Mg / Al-V2CT... x Smooth surface and no dendrites Figure 19 This is consistent with the aforementioned rapid diffusion dynamics.

[0162] We also assembled full batteries to evaluate their potential for practical applications, such as... Figure 20 As shown in a, Mg / Al-V2CT x The contact angle between the negative electrode and the APC electrolyte is 14°, which is much lower than that of Mg / V2CT. x (35°) and pure Mg (41°) indicate improved wettability, which is beneficial for uniform ion distribution. CV and EIS analyses confirm that Mg / Al-V2CT x Full cells exhibit faster electrochemical kinetics and lower charge transfer impedance (Ro). ct ()( Figure 20 b and Figure S24). In the rate test (0.1–2.0C, where 1C = 128.8 mAh / g), Mg / Al-V2CT xThe battery exhibits higher specific capacity at all rates, such as 90.4 mAh / g at 0.1C and 65.0 mAh / g at 2C, which is superior to Mg / V2CT. x And pure Mg batteries. Furthermore, Mg / Al-V2CT x The battery retains approximately 90.0% of its capacity after 500 cycles at a 1.0C rate. Figure 20 e) significantly superior to Mg / V2CT x (100 cycles, approximately 72.3%) and pure Mg (100 cycles, approximately 26.1%). These results make Mg / V2CT x It ranks among the leading magnesium-based anodes currently reported.

[0163] Example 5

[0164] This embodiment provides the application of the non-van der Waals coil structure of the present invention in a lithium metal battery system, including using a lithium metal composite material as a negative electrode of a lithium metal battery and evaluating its performance.

[0165] 5.1 Anode material preparation, battery assembly and testing

[0166] Anode material preparation: Following the method described in Example 3, non-van der Waals Al-V2CT was prepared at 250°C in an argon-filled glove box. x The coiled structure was mixed with molten lithium metal at a content of 0.4 wt.%, and after stirring, cooling, and hot rolling, Li / Al-V2CT was obtained. x Composite foil was used as the negative electrode. Pure Li foil was used as a comparison.

[0167] Battery assembly:

[0168] Symmetrical cells: Li / Al-V2CT with the same area x Alternatively, pure Li foil can be used as the positive and negative electrodes to assemble CR2032 coin cells. At 1 mA / cm²... 2 and 1mAh / cm 2 Electroplating / deposition is performed under the specified conditions.

[0169] Full cell: Li / Al-V2CT x Alternatively, pure Li can be used as the negative electrode, and commercially available lithium iron phosphate (LiFePO4) can be used as the positive electrode (loading ~2 mg / cm³). 2 Assemble the full battery. Cycling performance was tested at a rate of 1C (1C = 170 mAh / g) within a voltage range of 2.0 to 3.8V.

[0170] Electrolyte and membrane: 1M LiPF6 in EC / DEC (v / v = 1 / 1) electrolyte containing 5% FEC, Celgard 2325 membrane.

[0171] 5.2 Performance Testing

[0172] Full battery cycle performance test results ( Figure 21 The data shows that Li / Al-V2CT x The LiFePO4 full cell retained approximately 95% of its capacity after 100 cycles at 1C, significantly outperforming the pure LiFePO4 full cell (which retained approximately 83% of its capacity after 100 cycles). (SEM observation) Figure 22 The display shows that at 1mA / cm 2 After electroplating at current density for 5 hours, Li / Al-V2CT x The negative electrode surface exhibits a dense and uniform lithium deposition morphology; while the pure Li negative electrode surface shows obvious moss-like lithium and dendrite growth. Electrochemical impedance spectroscopy (EIS) analysis ( Figure 23 The data shows that Li / Al-V2CT x The electrode has a lower charge transfer impedance (Ri) than that of a pure Li electrode. ct This indicates that it has faster interfacial reaction kinetics.

[0173] This embodiment demonstrates that applying non-van der Waals coil structures to lithium metal battery systems can effectively improve lithium deposition behavior, suppress dendrite growth, and significantly enhance battery cycle life and rate performance. This result fully proves the universality of the strategy provided in this invention for "preparing high-performance metal hybrid anodes using non-van der Waals coil structures," which can be successfully extended to various metal-based battery systems such as lithium metal batteries, providing important experimental evidence for their practical application.

[0174] Example 6

[0175] This embodiment provides a preform infiltration method for preparing metal matrix composites. The technical concept is to first preform a non-van der Waals structure into a porous preform, and then mix it with molten metal or alloy. Utilizing the metal affinity and capillary force of the non-van der Waals structure, the molten metal spontaneously and rapidly infiltrates the preform completely. After cooling, a metal matrix composite is obtained.

[0176] In this embodiment, Al-V2CT is used. x A coiled dispersion was vacuum filtered and dried to form a porous film (preform). Then, under an argon atmosphere, molten Ga-In alloy was placed on the preform, and the molten metal was observed to spontaneously and rapidly permeate the preform completely within minutes. After cooling, Ga-In / Al-V2CT was obtained. x Composite materials.

[0177] The non-van der Waals coil structure, metal composite material, and metal composite foil provided by this invention, with their unique three-dimensional network structure, excellent metal affinity, high thermal stability, high mechanical strength, and outstanding electrical and thermal conductivity, have application prospects far beyond the high-performance metal battery anodes described above. The material system exhibits enormous application potential in aerospace (as lightweight, high-strength structural components and electromagnetic shielding materials), flexible electronics (as flexible conductors and sensors), biomedicine (as electrodes for implantable devices and biodegradable aggregates), transportation (for lightweight automotive components), and high-end electronic packaging (as thermal management materials), demonstrating broad industrial practical value as a multifunctional material platform.

[0178] Additional information on metal affinity:

[0179] The unique affinity of the non-van der Waals coil structure of this invention for molten metal stems not only from the chemical bonding on its surface but also from the strong capillary forces generated by its nanoscale hollow structure. This physical force is one of the key factors that enables the molten metal to spontaneously and rapidly fill and wet the internal cavities of the coil structure.

[0180] According to the classic Young-Laplace equation (Equation 1), the capillary force (P) c The size of the material is closely related to its interfacial properties and structural dimensions.

[0181] P c = 2γcosθ / r (1)

[0182] Among them, P c γ is the capillary force, θ is the surface tension of the molten metal, θ is the contact angle between the molten metal and the surface of the coiled structure, and r is the radius of the capillary channel of the coiled structure (i.e., the radius of the hollow structure).

[0183] From equation (1), we can see that the capillary force P c The capillary force is inversely proportional to the channel radius *r*. This means that when the channel radius decreases to the nanoscale, a huge capillary force will be generated. Taking molten magnesium (Mg) as an example (its surface tension γ is approximately 0.57 N / m, and its contact angle θ is approximately 68°), when the radius of the non-van der Waals coil structure is in the range of 10–50 nm, the estimated capillary force generated by the equation is as high as 8.6–43.0 MPa. This value is significantly higher than that of traditional micron-scale or bulk materials (whose capillary force P) c Approaching 0 Pa, it provides a powerful driving force for molten metal to overcome flow resistance and achieve efficient penetration and filling. Figure 24 ).

[0184] This theoretical calculation is in excellent agreement with our experimental results. It is this strong capillary force induced by the nanoconfinement effect, in synergy with surface chemical bonding, that constitutes the physicochemical basis of the "metal affinity" described in this invention, ensuring that the coiled structure can form a dense and robust composite material interface with various molten metals.

[0185] Additional test notes:

[0186] Thermal stability test: A Netzsch STA449F3 / F5 synchronous thermal analyzer was used to heat the sample from 40℃ to 800℃ at a heating rate of 10℃ / min under a dynamic argon atmosphere (flow rate 50mL / min), and the change in sample mass with temperature was measured.

[0187] Bulk / Powder Conductivity: An ST2253-SZ four-probe resistivity meter was used. A 50mg powder sample was placed in the sample chamber of the powder resistivity meter, leveled, and compacted under a pressure of 15MPa. After the reading stabilized, the resistivity (ρ) was read, and the conductivity was calculated using the formula σ=1 / ρ.

[0188] Thin film surface resistance: directly measured using a Loresta GP (MCP-T610) four-probe tester, and determined using formula R. s = (π / ln2)×(V / I) to calculate the resistance of the thin film.

[0189] Mechanical property testing: An ETM504C universal tensile testing machine was used, referring to standard GB / T 228.1. The composite foil was cut into standard dumbbell-shaped specimens, and uniaxial tensile tests were performed at a tensile rate of 1 mm / min until the specimens broke. The stress-strain curves were automatically recorded by the instrument software, and the tensile strength was taken as the peak stress of the curve.

[0190] Contact angle test: Inside the glove box, using a contact angle measuring instrument, approximately 2 μL of electrolyte is dropped onto the surface of the electrode material using the sitting drop method. The static contact angle is analyzed by the instrument software to evaluate the wettability between the electrode and the electrolyte.

[0191] Pulsed Joule heating: The "pulsed Joule heating" mentioned in this invention specifically refers to a non-equilibrium, ultrafast solid-state reaction strategy. Its core lies in directly applying short, high-energy current pulses to a heating substrate (such as carbon paper). A mixture of rolled MXene and a metal source is placed on the heating substrate, and a programmable heating and quenching process is performed. This generates instantaneous high temperatures (up to 1100K or higher) within a millisecond to second timescale (typically in the range of 0.1 seconds to several seconds), followed by rapid quenching and cooling during the intermittent period (power-off phase), as shown in Table 3 below.

[0192] This invention employs a cyclic pulse mode of "power on-power off" (e.g., power on for 0.1-0.5 seconds, power off for 0.5-2.0 seconds, cycled 2-5 times), rather than continuous heating. This intermittent energy input effectively avoids material structure damage, excessive grain growth, or compositional segregation caused by prolonged overheating, as shown in Table 4 below.

[0193] Table 3. Electrical parameters of pulsed Joule heating (0.3 seconds on, 1.0 second off)

[0194] Apply voltage (volts) Apply current (amperes) Power (watts) Fitted peak temperature (K) 18 15.5 186 1142 18 16 196 1156 18 16.5 209 1195 18 17 216 1206 18 17.5 224 1226 18 18 236 1260 18 18.5 246 1266 18 19 258 1295

[0195] Table 4. Synthesis of different Al-M2CTs using pulsed Joule heating (0.3 seconds on, 1.0 second off). x Conditions for curled structure

[0196] <![CDATA[Non-Van der Waals Al-M2CT x Curled structure]]> Apply voltage (volts) Apply current (amperes) Loop count <![CDATA[Al-V2CT x Curled structure 18 18 3 <![CDATA[Al-Ti2CT x Curled structure 18 14 3 <![CDATA[Al-(Nb 0.4 V 0.6 )2CT x Curled structure 18 18 3 <![CDATA[Al-(Ta 0.4 V 0.6 )2CT x Curled structure 18 19 3 <![CDATA[Al-(Ti 0.5 V 0.5 )2CT x Curled structure 18 18 3

[0197] The pulsed Joule heating described in this invention differs from traditional high-temperature sintering and conventional Joule heating in principle, equipment, and effect. Traditional high-temperature sintering / annealing is usually carried out in tube furnaces or muffle furnaces, relying on the equilibrium heating process of ambient thermal radiation and convection. The heating rate is slow (usually on the order of °C / min), and the holding time is long (several hours). Conventional Joule heating usually refers to continuous heating by applying a stable or continuously changing current, lacking the instantaneous ultra-high power density and rapid quenching effect brought about by the "pulse" in this invention.

[0198] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A metal-affinity coiled structure, characterized in that, The metal affinity coiled structure has a one-dimensional coiled morphology with a hollow structure, formed by the coiling of atomic layers composed of transition metal carbides or carbonitrides, and adjacent transition metal atomic layers are bonded by metal atoms to form a non-van der Waals structure.

2. The metal affinity coil structure as described in claim 1, characterized in that, The general formula of the transition metal carbides or carbonitrides is AM n+1 X n T x Where A is a bonding metal selected from at least one of Al, Sn, Ge, and Ga; M is a transition metal selected from at least one of V, Ti, Nb, Ta, Zr, Mo, W, and Cr; X is carbon and / or nitrogen; and T is a bonded metal. x This represents the surface end groups contained; n is between 1 and 4; Preferably, the general formula is A-M2XT x ; More preferably, A is Al, and M is selected from at least one of V, Ti, Nb, and Ta.

3. The metal affinity coil structure as described in claim 1 or 2, characterized in that, The radius of the hollow structure is 10 nanometers to 50 nanometers; and / or, The metal-affinity coiled structure exhibits thermal stability, with a mass loss of no more than 1 wt.% at 800°C; and / or, The electrical conductivity of the metal-affinity coiled structure is not less than 500 S / cm; and / or, The metal-affinity coil structure contains oxygen functional groups.

4. A method for preparing a metal affinity coiled structure as described in any one of claims 1 to 3, characterized in that the step include: Provides curled MXene and metal sources; The coiled MXene is mixed with the metal source and heat-treated by pulsed Joule heating in an inert atmosphere to form metal bonds between the metal atoms and the adjacent transition metal atom layers of the coiled MXene, thereby obtaining the metal affinity coiled structure. Optionally, after the heat treatment, the method further includes the step of treating with an acid solution to remove unreacted metal sources.

5. The preparation method according to claim 4, characterized in that, The pulse Joule heating has an on-time of 0.1-2.0 seconds and an off-time of 0.3-5.0 seconds; and / or, The peak temperature of the pulsed Joule heating is 1100K to 1300K; and / or, The power setting of the pulsed Joule heating is between 186 and 258 W; and / or, The number of cycles for the pulsed Joule heating is 1 to 10; and / or, The mass ratio of the curled MXene to the aluminum source is 5:1 to 1:

3.

6. A metal-based composite material, characterized in that, The composite material comprises a metal matrix and a metal affinity coil structure as described in any one of claims 1-5 dispersed in the metal matrix, wherein the metal affinity coil structure is bonded to the metal matrix by interfacial chemical bonding and capillary forces.

7. The metal matrix composite material as described in claim 6, characterized in that, The metal-affinity coiled structure is present in the composite material at a content of 0.1 wt.% to 1.0 wt.%; preferably, between 0.2 wt.% and 0.6 wt.%; and / or, The metal matrix is ​​selected from one or an alloy of metals with a melting point ≤800℃; preferably, it is selected from magnesium, lithium, gallium, aluminum, indium, tin, lead, sodium, zinc, aluminum or alloys thereof; and / or, The hollow structure of the metal-affinity coiled structure is filled with the metal matrix; and / or, The interfacial chemical bonding is an M'-OM chemical bond, where M' represents a metal atom of the metal matrix, O represents an oxygen atom, and M represents a transition metal atom.

8. The metal matrix composite material as described in claim 6 or 7, characterized in that, The tensile strength of the metal matrix composite material is increased by more than 60% compared to that of the metal matrix material; preferably, it is increased by more than 100%, and more preferably, it is increased by more than 120%. Alternatively, when the metal matrix is ​​magnesium or a magnesium alloy, the tensile strength of the metal matrix composite material is not less than 120 MPa; preferably, not less than 200 MPa. Alternatively, when the metal matrix is ​​lithium, the tensile strength of the metal matrix composite material is not less than 1 MPa; preferably, not less than 1.5 MPa.

9. A method for preparing a metal matrix composite material as described in any one of claims 6 to 8, characterized in that, step... include: Under an inert atmosphere, the metal affinity coiled structure of any one of claims 1 to 5 is mixed with a molten metal matrix, and the metal affinity and capillary force of the coiled structure are used to make it uniformly dispersed in the molten metal and form an interfacial bond, and then cooled and solidified.

10. The preparation method according to claim 9, characterized in that, The metal-affinity coiled structure is prepared as a porous preform before mixing, and then bonded to the preform via spontaneous infiltration of the molten metal matrix; and / or, The preparation method further includes a step of rolling the obtained metal matrix composite material to obtain a metal composite foil; preferably, the thickness of the metal composite foil is between 5 and 500 micrometers.

11. An electrode, characterized in that, The electrode comprises a metal-affinity coiled structure as described in any one of claims 1-5; or, a metal-based composite material as described in any one of claims 6 to 10; preferably, the electrode is the negative electrode of the battery; more preferably, the electrode is the negative electrode of a magnesium metal battery or a lithium metal battery.

12. An electrochemical device, characterized in that, The electrochemical device comprises the electrode as described in claim 11; preferably, the electrochemical device is a battery.

13. Use of a metal affinity coil structure as described in any one of claims 1-5 in reducing the surface tension of molten metal and / or improving the mechanical strength of metal.

14. The application of a metal affinity coil structure as described in any one of claims 1-5, or a metal matrix composite material as described in any one of claims 5 to 10, in aerospace, flexible electronics, transportation, biomedicine, high-end electronic packaging, electromagnetic shielding, flexible conductors, sensors, lightweight and high-strength structural components, etc.

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