Electromagnetic shielding material, composite material, fabric and use thereof

Abstract

This invention discloses an electromagnetic shielding material, a composite material, a fabric, and their uses. The electromagnetic shielding material contains MXene nanorolls, which are MXene materials with a one-dimensional hollow roll structure. The excellent electromagnetic shielding performance of these MXene nanorolls is mainly due to the following reasons: First, the hollow tubular structure of the MXene nanorolls allows incident electromagnetic waves to be reflected and absorbed multiple times within the tubular structure. Second, the one-dimensional structure can improve the conductivity of the film, and the increased conductivity further promotes the electromagnetic shielding performance. The combined effect of these two aspects results in the high-performance electromagnetic shielding of the MXene nanoroll film.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic shielding, and in particular relates to an electromagnetic shielding material, composite material, fabric and its uses. Background Technology

[0002] The widespread use of electronic products and equipment has greatly facilitated people's lives and production, but it has also generated a large amount of electromagnetic radiation, causing serious electromagnetic pollution and harm, thus leading to a series of social and environmental problems. The ideal operating state for electronic equipment is one where it is not interfered with by external electromagnetic waves, ensuring the signal fidelity and stability of the electronic product, while simultaneously not generating electromagnetic pollution harmful to the human body and other external devices. Therefore, it is necessary to find ways to block the propagation of electromagnetic waves, i.e., electromagnetic shielding technology. Materials that can reflect and absorb electromagnetic waves, thereby reducing their transmittance and achieving shielding against external electromagnetic interference and blocking their own electromagnetic radiation, are called electromagnetic shielding materials.

[0003] The electromagnetic shielding performance of a material can be measured by its electromagnetic shielding effectiveness, which is defined as a logarithmic function of the ratio of the transmitted intensity to the incident intensity of an electromagnetic wave. Higher electromagnetic shielding effectiveness indicates lower transmitted intensity of electromagnetic waves and better electromagnetic shielding performance. Traditional electromagnetic shielding materials are mainly metals, such as copper and aluminum. However, the high density, difficulty in processing, and poor corrosion resistance of metals greatly limit their application. Two-dimensional materials, such as graphene and MXenes, have become recognized as new types of electromagnetic shielding materials due to their high electrical conductivity, large specific surface area, and good mechanical properties.

[0004] However, currently reported graphene electromagnetic shielding materials all require high-temperature graphitization, which is a complex, time-consuming, and costly process, posing significant obstacles to practical applications. Meanwhile, sheet-like MXenes materials are prone to agglomeration and layer stacking during film formation, reducing conductivity and affecting electromagnetic shielding effectiveness. Although carbon nanotubes possess excellent conductivity and can significantly improve electromagnetic shielding efficiency as fillers, their tendency to agglomerate leads to uneven dispersion, thus impacting shielding effectiveness. Summary of the Invention

[0005] The object of the present invention is to provide, in a first aspect, the use of MXene nanorolls as electromagnetic shielding materials, wherein the MXene nanorolls are MXene materials having a one-dimensional hollow roll structure.

[0006] A second aspect of the present invention provides a battery shielding material comprising the aforementioned MXene nanorolls.

[0007] In some embodiments, the chemical formula of the above-mentioned MXene nanorolls is represented as Mn+1 X n T x Where M is selected from one or more transition metal elements, X is selected from one, two, or three of carbon, nitrogen, or boron elements, n is between 1, 2, 3, or 4, and T x For functional groups.

[0008] In some embodiments, M includes one, two, or more of the elements Ti, V, Nb, Cr, Ta, Hf, Mo, W, Fe, Mn, Y, or Sc; and / or, T x The functional group includes elements of the sixth and / or seventh main groups.

[0009] In some embodiments, the hollow roll structure is formed by rolling up a two-dimensional MXene material; and / or, the MXene nanoroll is open at both ends; and / or, the one-dimensional structure of the MXene nanoroll is linear; and / or, the hollow roll structure is formed by rolling up a single sheet and / or a single layer of two-dimensional MXene material.

[0010] In some embodiments, the wall thickness of the MXene nanoroll is between 0.3 nm and 50 nm; and / or, the length of the MXene nanoroll is between 0.1 μm and 100 μm; and / or, the diameter of the MXene nanoroll is between 10 nm and 200 nm.

[0011] In some embodiments, the electromagnetic shielding material further includes a two-dimensional material; and / or, the electromagnetic shielding material further includes a one-dimensional material; and / or, the electromagnetic shielding material further includes a zero-dimensional material.

[0012] In some embodiments, the two-dimensional material is selected from one or more of two-dimensional MXene materials, graphene, and graphite sheets; the one-dimensional material is selected from one or more of carbon nanotubes, graphene rolls, or metal wires; and the zero-dimensional material is carbon material and / or metal nanoparticles.

[0013] A third aspect of the present invention provides an electromagnetic shielding composite material, comprising the aforementioned electromagnetic shielding material and a matrix material, wherein the electromagnetic shielding material is dispersed in the matrix material; or, the electromagnetic shielding material is a thin film or coating distributed on the surface of the matrix material.

[0014] A fourth aspect of the present invention provides an electromagnetic shielding fabric comprising the electromagnetic shielding material described above.

[0015] The fifth aspect of the present invention provides the above-mentioned electromagnetic shielding material; or, the above-mentioned electromagnetic shielding composite material; or, the application of the above-mentioned electromagnetic shielding fabric in communication equipment, computers, energy storage power stations, electric vehicles, and unmanned aerial vehicles.

[0016] The MXene nanorolls of this invention exhibit excellent electromagnetic shielding performance as an electromagnetic shielding material, mainly due to the following reasons: First, the hollow tubular structure of the MXene nanorolls allows incident electromagnetic waves to be reflected and absorbed multiple times within the tubular structure. Second, the one-dimensional structure can improve the conductivity of the film, and the increased conductivity further promotes the electromagnetic shielding performance. The combined effect of these two aspects results in the high-performance electromagnetic shielding of the MXene nanoroll film.

[0017] In addition, the prepared MXene nanorolls can be mass-produced and monodisperse. For the fabrication of electromagnetic shielding films, MXene nanorolls do not accumulate sheets during the film formation process, avoiding the impact of agglomeration on electromagnetic shielding, thereby greatly improving the conductivity and electromagnetic shielding performance of the electromagnetic shielding film. Attached Figure Description

[0018] Figure 1 XRD patterns (a) of the MAX phase material and the two-dimensional MXene material in Embodiment 1 of the present invention; SEM images of the MAX phase material (b) and the etched material (c, d);

[0019] Figure 2 SEM images of samples obtained in Example 1 of this invention with positive ion pair reagent mass concentrations of 1 wt.% (a), 5 wt.% (b), 10 wt.% (c), and 20 wt.% (d) and under stirring.

[0020] Figure 3 SEM image of a sample obtained in Example 1 of this invention with a positive ion-pairing reagent concentration of 20 wt.% but without stirring;

[0021] Figure 4 TEM image (a) and tube diameter distribution statistics (b) of MXene nanorolls obtained in Example 1 of this invention;

[0022] Figure 5 These are TEM images (a and b) and HRTEM images (c and d) of MXene nanorolls at different magnifications in Example 1 of the present invention.

[0023] Figure 6 This is an elemental distribution diagram of the MXene nanorolls in Example 1 of the present invention;

[0024] Figure 7 XRD patterns (a) of the MAX phase material and the two-dimensional MXene material in Embodiment 2 of the present invention; SEM images of the MAX phase material (b) and the two-dimensional MXene material (c);

[0025] Figure 8TEM image (a) and tube diameter distribution statistics (b) of MXene nanorolls obtained in Example 2 of this invention;

[0026] Figure 9 The images shown are TEM images (a) and HRTEM images (b and c) at different magnifications of MXene nanorolls in Example 2 of this invention, and elemental distribution images (e-j).

[0027] Figure 10 XRD patterns (a) of the MAX phase material and the two-dimensional MXene material in Embodiment 3 of the present invention; SEM images of the MAX phase material (b) and the two-dimensional MXene material (c);

[0028] Figure 11 The images are SEM images of the two-dimensional MXene material in Example 3 of the present invention at stirring times of 1 min (a), 10 min (b), and 30 min (c).

[0029] Figure 12 V2AlC and V2CT in Embodiment 4 of the present invention x XRD patterns (a), SEM images of V2AlC (b), SEM (c), TEM (d), and HRTEM (e) images of MXene nanorolls;

[0030] Figure 13 The images shown are (a) and (b, c) cross-sectional SEM images of the MXene nanoroll film at different magnifications in Example 5 of the present invention; and (d) and (e, f) cross-sectional SEM images of the MXene nanosheet film at different magnifications.

[0031] Figure 14 The images show (a) of the MXene nanofilm in Example 5 of this invention, (b) the electromagnetic performance test of MXene nanofilms of different thicknesses, and (c) a comparison of the electromagnetic performance of MXene nanofilms and MXene nanosheets. Detailed Implementation

[0032] 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.

[0033] 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.

[0034] Example 1

[0035] This embodiment provides an MXene nanoroll with the chemical formula V2B. 0.28 C 0.57 N 0.15 T x The specific steps of the preparation method are as follows:

[0036] 1) Preparation of two-dimensional MXene materials from MAX phase materials

[0037] MAX phase material V2AlB 0.28 C 0.57 N 0.15 Etching was performed at 90°C for 48 hours using an etchant to obtain a mixture (5 mg / ml) containing the etchant. The etchant was a mixture of concentrated hydrochloric acid (30 wt.%) and NaF, with a molar ratio of NaF to HCl of 1:1. The resulting etchant was a two-dimensional MXene material, labeled as V2(B). x C y N 1-x-y )T x ;

[0038] After centrifuging and washing the mixture containing the etching material, the resulting etching material was characterized. Figure 1 XRD comparison of the MAX phase material and the etched material shows that the (002) diffraction peak of the etched material shifts to a lower angle, and the characteristic peaks of other MAX phases disappear. This is because the A component (Al element) in the MAX phase material is selectively etched, resulting in a two-dimensional MXene material with increased interlayer spacing between the sheets. SEM images show that the MAX phase material exhibits a typical layered bulk morphology. Figure 1 b); while the etched material exhibits a sheet-like, stacked accordion-like morphology ( Figure 1 (c) and (d) show a significant increase in interlayer spacing, consistent with the previous XRD pattern results. Figure 1 c also shows that the etched material has a sheet diameter of about 1μm to 10μm, with most of the sheets having a diameter of about 5μm.

[0039] 2) Fabrication of MXene nanorolls from two-dimensional MXene materials

[0040] Add 1 wt.% to 20 wt.% of tetrabutylammonium hydroxide (TBAOH) aqueous solution to the etching material obtained in step 1 above, stir magnetically (1500 r / min) for 5 min, then sonicate (1000 W) for 30 min, and centrifuge and wash multiple times to obtain the purified sample.

[0041] Figure 2 SEM images of samples with TBAOH added at concentrations of 1 wt.%, 5 wt.%, 10 wt.%, and 20 wt.%, respectively, are shown in ax² to d. It can be seen that when 1 wt.% TBAOH is added, the edges of the two-dimensional MXene material exhibit a curled state. Figure 2 a) Increasing the TBAOH concentration to 5 wt.% resulted in more pronounced edge curling in the two-dimensional MXene material. Figure 2 b) Further increasing the TBAOH concentration to 10 wt.%, the two-dimensional MXene material in the sample mostly exhibited a nanoroll state. Figure 2 c) When the TBAOH concentration increased to 20 wt.%, the two-dimensional MXene material in the sample was completely transformed into MXene nanorolls. Figure 2 d). Figure 2 a~d clearly demonstrate the process of MXene nanorolls gradually forming from the curling of two-dimensional MXene materials, and the one-dimensional hollow nanoroll structure formed by the curling of the edges of the same two-dimensional MXene material. Figure 3 SEM images of a sample with 20 wt.% TBAOH added but without stirring or sonication are shown. The sample exhibits a thin and flexible morphology but does not curl, indicating that external force is crucial for the formation of MXene nanorolls.

[0042] The above examples also demonstrate that adding an appropriate amount of positive ion-pairing reagent to the liquid phase significantly accelerates the formation of MXene nanotubes. For instance, adding 20 wt.% TBAOH only requires 5 minutes of stirring and 10 minutes of sonication to obtain fully curled MXene nanotubes. In contrast, adding only 1 wt.% TBAOH, while producing curling under the same conditions, does not result in nanotube structures and requires extended stirring time. This can be explained by the fact that higher concentrations of positive ion-pairing reagent graft more alkyl chains onto the surface of the two-dimensional MXene material, resulting in a greater external force under the same force, thus facilitating the rapid formation of one-dimensional hollow roll structures. In the optimized experiments, the amount of positive ion-pairing reagent added can range from 1 wt.% to 50 wt.%. The optimal amount can be obtained through a limited number of experiments, depending on the type of MXene material and the negative charge on its surface.

[0043] Stirring induces unidirectional flow in the liquid phase, providing a continuous and uniform external force for the rolling process, which is crucial for obtaining large quantities and uniform MXene nanorolls. Characterization results show that the two-dimensional MXene material was almost completely transformed into MXene nanorolls, as demonstrated by SEM (e.g.,...). Figure 2 d) and TEM (e.g.) Figure 6 a) As shown in the photograph, this invention enables the large-scale preparation of uniformly monodisperse MXene nanorolls, which is of great significance for subsequent applications.

[0044] In other embodiments, the positive ion pairing reagent may also be selected from one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrapentylammonium hydroxide. These reagents differ from TBAOH in this embodiment in that the length of the alkyl chain is different, and it is reasonable to predict that they can also produce the same technical effect.

[0045] The obtained MXene nanorolls were subjected to transmission electron microscopy (TEM) analysis, such as... Figure 4 As shown in Figure a, it can be seen that MXene nanorolls have a significant one-dimensional morphology. The length of the MXene nanorolls is between 0.5 μm and 5 μm, corresponding to the sheet diameter of the two-dimensional MXene material before winding. Each MXene nanoroll is independently dispersed (monodispersed). Figure 4 b. Statistical analysis of the diameter of MXene nanotubes showed that the diameter of the nanotubes ranged from 20nm to 80nm, with the highest content of MXene nanotubes at a diameter of 40nm, accounting for more than 40%.

[0046] Figure 5 Images a and b show TEM images of MXene nanorolls at different magnifications. It is clear that the MXene nanorolls possess a hollow roll structure formed by rolling up a single sheet of two-dimensional MXene material, exhibiting a straight one-dimensional morphology, open ends, and smooth walls. Figure 5 The high-resolution electron microscopy (HRTEM) images c and d show that the walls of the MXene nanorolls consist of only 2 to 3 layers of MXene, with an interlayer spacing of 1.08 nm, meaning the wall thickness is only 3 to 4 nm. This ultra-thin wall indicates that the MXene nanorolls of this invention are formed by rolling up a single layer of two-dimensional MXene material. Figure 5 d It can also be seen that the tube walls of MXene nanorolls show the typical hexagonal lattice of MXene, indicating that MXene nanorolls have a crystalline structure.

[0047] Figure 6The elemental distribution of MXene nanorolls as shown by TEM analysis is presented. It can be seen that the MXene nanorolls contain V, B, C, N, O, and F elements, and these elements are uniformly distributed. O and F are functional group elements on the surface of the MXene nanorolls, and their chemical formula is V₂(B₂)₃. x C y N 1-x-y )T x match.

[0048] This invention does not limit the source of the MAX phase material; the MAX phase material can be commercially available or prepared by high-temperature sintering. For example, the MAX phase material V2AlB in this embodiment... 0.28 C 0.57 N 0.15 The material is prepared by high-temperature sintering. The steps include: sintering the elemental substances or compounds of each element according to the stoichiometric ratio in the chemical formula of the MAX phase material at high temperature. In this embodiment, more specifically, vanadium powder (V), aluminum powder (Al), boron powder (B), carbon powder (C), and nitrogen carbonide (CN) are mixed in a molar ratio of 2:1:0.85:0.42:0.15 and ball-milled. The mixture is then placed in a high-temperature sintering furnace and sintered at 1500°C for 24 hours under an argon atmosphere, and then cooled to room temperature.

[0049] In some embodiments, the etchant in step 1 can also be replaced with hydrofluoric acid solution, or a solution of NaF + nitric acid, NaF + sulfuric acid, LiF + hydrochloric acid, or Li + nitric acid; or other etching methods, such as accordion-shaped MXene material obtained by vapor phase etching.

[0050] Example 2

[0051] This embodiment provides another MXene nanoroll with the chemical formula: V2C 0.5 N 0.5 T x The preparation methods include:

[0052] 1) Preparation of two-dimensional MXene materials from MAX phase materials

[0053] MAX phase material V2AlC 0.5 N 0.5 A mixture of concentrated hydrochloric acid (30 wt.%) and NaF, with a molar ratio of NaF to HCl of 1:1, was used for etching at 40°C for 48 hours. The resulting etched material was a two-dimensional MXene material, labeled as: V2(C x N 1-x )T x .

[0054] pass Figure 7The XRD comparison of a shows that, compared with the MAX phase material, the (002) diffraction peak of the etched material shifts to a lower angle, and the characteristic peaks of other MAX phases disappear. This is because the A component (Al element) in the MAX phase material is selectively etched, and the interlayer spacing between its sheets increases. Figure 7 SEM images b and c show that the MAX phase material exhibits a typical layered bulk morphology. After etching, the etched material exhibits an accordion-like morphology of stacked sheets, with a significantly increased interlayer spacing, which is consistent with the previous XRD pattern results. The sheet diameter is approximately between 5 μm and 15 μm.

[0055] 2) Obtaining MXene nanorolls by rolling up two-dimensional MXene materials

[0056] Add 1g of the above etching material to 50ml of a 30wt.% TBAOH aqueous solution, stir magnetically for 10min, and then centrifuge and wash several times to obtain the purified sample.

[0057] TEM test results of the sample are as follows Figure 8 As shown in a, it can be seen that the sample also exhibits a significant one-dimensional morphology. The length of the MXene nanorolls is greater than 5 μm, which corresponds to the sheet diameter of the two-dimensional MXene material before winding. This indicates that the MXene nanorolls of the present invention are obtained by rolling up two-dimensional MXene sheets. Figure 8 b. Statistical analysis of the diameter of MXene nanotubes showed that the diameter of hollow rolls ranged from 20nm to 140nm, with the highest content of MXene nanotubes at a diameter of 60nm, accounting for more than 30%.

[0058] Figure 9 The TEM image of a shows that the ports of the MXene nanorolls are open. Figure 9 b and c are HRTEM images, which show the hollow roll structure of MXene nanorolls, with approximately 3 to 6 MXene layers forming the tube walls. Figure 9 e-j shows the elemental distribution of MXene nanorolls. It can be seen that MXene nanorolls contain V, C, N, O, and F elements, and these elements are uniformly distributed. O and F are functional group elements on the surface of the MXene nanorolls, and their chemical formula is V2(C). x N 1-x )T x match.

[0059] The MAX phase material in this embodiment is prepared by high-temperature sintering. The steps include: obtaining the elemental or compound form of each element by high-temperature sintering according to the elemental stoichiometry in the chemical formula of the MAX phase material. In this embodiment, V2AlC 0.5 N 0.5The preparation method includes: mixing vanadium powder (V), aluminum powder (Al), aluminum nitride (AlN), and carbon powder in a molar ratio of 2:0.5:0.5:0.5 and ball milling them, then placing them in a high-temperature sintering furnace and sintering them at a high temperature of 1500℃ for 24 hours under an argon atmosphere, and then cooling them to room temperature to obtain the final product.

[0060] Example 3

[0061] This embodiment provides an MXene nanoroll with the chemical formula Ti3CNT. x The preparation method includes the following steps:

[0062] 1) Preparation of two-dimensional MXene materials from MAX phase materials

[0063] The MAX phase material Ti3AlCN was etched at 40 °C for 48 h using a mixture of concentrated hydrochloric acid (30 wt.%) and LiF, wherein the molar ratio of LiF to HCl was 1:1, to obtain a two-dimensional MXene material, labeled Ti3CNT. x .

[0064] pass Figure 11 The XRD comparison of a shows that, compared with the MAX phase material, the (002) diffraction peak of the etched material shifts to a lower angle, and the characteristic peaks of other MAX phases disappear. Figure 11 SEM images b and c show that the MAX phase material exhibits a typical layered bulk morphology; the etched material exhibits an accordion-like morphology of stacked sheets, with a significantly increased interlayer spacing. The sheet diameter is approximately 3μm to 5μm.

[0065] 2) Obtaining MXene nanorolls by rolling up two-dimensional MXene materials

[0066] The above-mentioned etching material was added to a 10 wt.% TBAOH aqueous solution, and after magnetic stirring for 30 min, it was centrifuged and washed multiple times to obtain a purified sample. Figure 11 Images a through c show SEM images of samples stirred for 1 min, 10 min, and 30 min, respectively. They reveal that the two-dimensional MXene material gradually curls, eventually forming MXene nanorolls with a diameter of approximately 200 nm to 300 nm. This demonstrates that the duration of external force application influences the formation of MXene nanorolls. Extending the stirring time can also yield MXene nanorolls even at lower concentrations of positive ion-paired reagents.

[0067] Example 4

[0068] This embodiment provides another MXene nanoroll for use as a conductive component in conductive pastes, with the chemical formula: V2CT. x Preparation methods include:

[0069] 1) The MAX phase material V2AlC was etched at 90°C for 48 hours using concentrated hydrochloric acid-NaF etchant to obtain the two-dimensional MXene material V2CT. x ;

[0070] 2) The above two-dimensional MXene material was added to a 20 wt.% TBAOH intercalating agent solution, and after magnetic stirring for 5 min, it was centrifuged, washed and purified several times, and then dried to obtain MXene nanorolls;

[0071] Figure 12 a gives V2AlC and V2CT x XRD patterns; Figure 12 b provides a SEM image of V2AlC, which shows that it is a blocky material; Figure 12 c and d give the MXene nanoroll (V2CT) x The SEM and TEM images show that MXene nanorolls have a monodisperse one-dimensional hollow nanoroll morphology, with tube diameters ranging from 40 nm to 70 nm and lengths ranging from 2 to 5 μm. Figure 12 The image provided by e shows that the wall thickness of the MXene nanorolls is between 2 nm and 3 nm, indicating that they have ultrathin walls.

[0072] Using a similar method, the applicant has also prepared other types of MXene nanorolls with the same structural characteristics, including: Ti2CT x Ti3C2T x Nb2CT x TiNbCT x Cr2CT x Ti3CNT x Ti2CT x Ti2C 0.5 N 0.5 T x Ti 0.5 V 0.5 C 0.5 N 0.5 T x V2CT x V2C 0.75 N 0.25 T x V2B 0.28 C 0.57 N 0.15 T x 、(V 0.8 Cr 0.2 )2B 0.33 C 0.67 T x 、(V 0.8 Cr0.2 )2CT x 、(V 0.8 Fe 0.2 )2B 0.33 C 0.67 T x 、(V 0.8 Mn 0.2 )2B 0.33 C 0.67 T x 、(V 0.8 Fe 0.2 )2B 0.28 C 0.57 N 0.15 T x 、(V 0.8 Mn 0.2 )2B 0.28 C 0.57 N 0.15 T x Therefore, the preparation method of the present invention has a certain degree of universality for two-dimensional MXene materials. The types of MXene nanorolls prepared by the present invention are not limited to the examples given in the above embodiments. Other types of two-dimensional MXene materials can be wound to obtain the MXene nanoroll structure of the present invention by adjusting the experimental methods and conditions.

[0073] Since the MXene nanorolls of the present invention are formed by rolling up two-dimensional MXene materials, the length of the MXene nanorolls in the one-dimensional direction is related to the sheet diameter of the two-dimensional MXene materials. For two-dimensional MXene materials, the sheet diameter can be distributed between 0.1 μm and 100 μm. Therefore, we can reasonably predict that the length of the MXene nanorolls can also be within this range.

[0074] Example 5

[0075] This embodiment provides an electromagnetic shielding film and its preparation method. The steps include: filtering out the solvent from an MXene nanoroll dispersion using a vacuum filtration device, forming a thin film on the filter membrane with the MXene nanorolls, and then peeling off the filter membrane after drying to obtain a flexible battery shielding film. By controlling the volume of the filtered dispersion, the thickness of the film on the filter membrane can be controlled, resulting in battery shielding films of different thicknesses after drying.

[0076] The specific preparation steps include: preparing the MXene nanorolls obtained in Example 1 into a dispersion with a concentration of 5 mg / ml, taking different volumes of the dispersion for vacuum filtration, forming a film on a filter membrane with a diameter of 4 cm, and drying to obtain MXene nanoroll electromagnetic shielding films with thicknesses of 5 μm, 10 μm, 20 μm and 30 μm respectively (hereinafter referred to as: MXene nanoroll film). Figure 13a shows a photograph of the MXene nanofiber membrane. Figure 13 b and c show cross-sectional SEM images of the MXene nanoroll film at different magnifications. It can be seen that the MXene nanoroll film has a uniform thickness and the cross-section exhibits a nanoroll arrangement morphology.

[0077] For comparison, the MXene nanorolls mentioned above were replaced with the two-dimensional MXene material prepared in Example 1. Under the same preparation conditions, circular films were also formed by filtration and dried to obtain an electromagnetic shielding film of two-dimensional MXene material. Figure 13 d, hereinafter referred to as MXene nanosheet film), Figure 13 e and f are cross-sectional SEM images of the MXene nanosheet film at different magnifications. It can be seen that the MXene nanosheet film has a uniform thickness and is clearly distributed in layers.

[0078] The conductivity of the MXene nanoroll powder, MXene nanoroll film (10 μm thick), two-dimensional MXene material powder, and MXene nanosheet film (10 μm thick) obtained above was tested. The test method was as follows: the conductivity was tested using the four-probe method. The method was as follows: 50 mg of powder sample or film was added to the sample cell of the four-probe powder resistance meter, and it was spread out. Then, the four-probe powder resistance meter was turned on, and the handle was rotated to move the upper probe of the resistance meter downward. Then, the pressure was applied to 15 MPa. After the resistance meter reading stabilized, the resistivity reading was read. Then, the conductivity was obtained according to the conversion relationship of conductivity = 1 / resistivity. The results are shown in the table below:

[0079]

[0080] As shown in the table above, in the powder state, the MXene nanorolls of this invention have an order of magnitude higher conductivity than the two-dimensional MXene sheets. This is because, on the one hand, MXene nanorolls have a one-dimensional structure, resulting in better directional conductivity; on the other hand, MXene nanorolls are a one-dimensional network-like interconnection, and their contact resistance is significantly lower than that of the two-dimensional MXene sheets, which are sheet-like interconnections. Conductivity tests on both the MXene nanoroll film and the MXene nanosheet film also showed the same results: the conductivity of the MXene nanoroll film is significantly higher than that of the MXene nanosheet film.

[0081] The MXene nanofilms of different thicknesses obtained above ( Figure 14 a) Electromagnetic shielding performance testing was conducted. The testing method involved cutting the obtained films of different thicknesses into rectangular pieces of 2*4cm size and testing them using electromagnetic shielding testing equipment (WR-90 rectangular waveguide-N5234B dual-port vector network analyzer). The test results are as follows: Figure 14As shown in b, it can be seen that the electromagnetic shielding performance of the MXene nanofilm increases with increasing thickness. Figure 14 c presents a comparison of the electromagnetic shielding performance of MXene nanoroll films and MXene nanosheet films of the same thickness (30 μm). The electromagnetic shielding effectiveness of the MXene nanoroll film is 81.2 dB, while that of the MXene nanosheet film of the same material is only 38.94 dB. The main reason for the difference in electromagnetic shielding effectiveness between the two materials is the tubular structure of the nanorolls, in which incident electromagnetic waves are reflected and absorbed multiple times. Secondly, the one-dimensional structure can improve the conductivity of the film, and the increase in conductivity further promotes the electromagnetic shielding performance. The combined effect of these two aspects results in the high electromagnetic shielding performance of the MXene nanoroll film. It is worth noting that the electromagnetic shielding effectiveness of the MXene nanoroll film disclosed in this invention is higher than the highest reported value of Ti3C2T. x MXene material (77.9dB). Therefore, this invention provides a novel high-performance electromagnetic shielding material.

[0082] 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. An electromagnetic shielding material, characterized in that, The electromagnetic shielding material contains MXene nanorolls, which are MXene materials with a one-dimensional hollow roll structure. The hollow roll structure is formed by rolling up two-dimensional MXene materials, and the diameter of the MXene nanorolls is between 10 nm and 200 nm. The one-dimensional structure of the MXene nanorolls is linear.

2. The electromagnetic shielding material as described in claim 1, characterized in that, The chemical formula of the MXene nanorolls is M n+1 X n T x Where M is selected from one or more transition metal elements, and X is selected from one, two, or three of carbon, nitrogen, or boron. n T is between 1, 2, 3 or 4. x For functional groups.

3. The electromagnetic shielding material as described in claim 2, characterized in that, The M includes one, two, or more of the following elements: Ti, V, Nb, Cr, Ta, Hf, Mo, W, Fe, Mn, Y, or Sc. And / or, T x The functional group includes elements of the sixth and / or seventh main groups.

4. The electromagnetic shielding material as described in claim 1, characterized in that, The MXene nanoroll has openings at both ends; And / or, the hollow roll structure is formed by rolling up a single sheet and / or a single layer of two-dimensional MXene material.

5. The electromagnetic shielding material according to any one of claims 1 to 4, characterized in that, The thickness of the tube wall of the MXene nanoroll is between 0.3 nm and 50 nm; And / or, the length of the MXene nanorolls is between 0.1 μm and 100 μm.

6. The electromagnetic shielding material according to any one of claims 1 to 4, characterized in that, The electromagnetic shielding material also includes two-dimensional materials; And / or, the electromagnetic shielding material further includes a one-dimensional material; And / or, the electromagnetic shielding material may also include zero-dimensional materials.

7. The electromagnetic shielding material as described in claim 6, characterized in that, The two-dimensional material is one or more of two-dimensional MXene material, graphene, and graphite sheets.

8. The electromagnetic shielding material as described in claim 6, characterized in that, The one-dimensional material is one or more of carbon nanotubes, graphene rolls, or metal wires.

9. The electromagnetic shielding material as described in claim 6, characterized in that, The zero-dimensional material is a carbon material and / or metal nanoparticles.

10. An application of MXene nanorolls for electromagnetic shielding, characterized in that, The MXene nanorolls are MXene materials with a one-dimensional hollow roll structure, which is formed by rolling up two-dimensional MXene materials. The diameter of the MXene nanorolls is between 10 nm and 200 nm.

11. An electromagnetic shielding composite material, characterized in that, The material comprises an electromagnetic shielding material as described in any one of claims 1 to 9 and a matrix material, wherein the electromagnetic shielding material is dispersed in the matrix material; Alternatively, the electromagnetic shielding material may be a thin film or coating distributed on the surface of the substrate material.

12. An electromagnetic shielding fabric, characterized in that, The electromagnetic shielding fabric contains the electromagnetic shielding material as described in any one of claims 1 to 9.

13. An electromagnetic shielding material as described in any one of claims 1 to 9; or, an electromagnetic shielding composite material as described in claim 11; or, an electromagnetic shielding fabric as described in claim 12, used in communication equipment, computers, energy storage power stations, electric vehicles, and unmanned aerial vehicles.

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