Composite conductive paste, electrode plate, preparation method of electrode plate and battery

Abstract

The invention discloses composite conductive slurry, an electrode plate, a preparation method of the electrode plate and a battery. Conductive components in the composite conductive slurry comprise metal powder and an MXene nano roll; the MXene nano volume is made of an MXene material with a one-dimensional hollow volume structure; the hollow roll structure is formed by rolling a single piece and / or a single layer of two-dimensional MXene material. The MXene nanoscroll belongs to the microstructure change of an MXene material and still retains the conductive characteristic of the MXene material, but the novel MXene nanoscroll is used for the conductive slurry, so that the conductive characteristic of the material is utilized, and the special one-dimensional hollow morphology of the MXene nanoscroll is combined.

Description

[0001] This application is a divisional application, and its parent application is a patent application for invention with the application date of March 9, 2022, application number 202210225288.7, and invention title "Conductive Agent, Conductive Paste and Their Preparation Methods and Uses". Technical Field

[0002] The present invention belongs to the field of conductive materials, and particularly relates to a composite conductive paste, an electrode sheet, and their preparation methods and batteries. Background Art

[0003] Currently, the conductive pastes that have been studied more are mixtures of graphene, carbon nanotubes, Ag, Au, Pd, Cu and other nanoparticles and epoxy resins. First of all, for conductive pastes of noble metal powder - epoxy resin type, due to their high cost and complex manufacturing process, their large-scale use is restricted; for carbon materials such as graphene and carbon nanotubes with ultra-high conductivity and chemical stability, in the mixing process, graphene and active substances are in "plane - point" contact, carbon nanotubes and active substances are in "line - point" contact, and graphene and carbon nanotube composite conductive pastes can achieve plane - line - point contact, greatly improving the overall electrode performance, while reducing the use of conductive agents in the electrode, thereby increasing the overall capacity of the battery. However, currently, due to the strong van der Waals force and high specific surface area, graphene and carbon nanotubes are very easy to agglomerate and stack severely in the conductive paste, which greatly restricts the storage and practical application of the conductive paste. Therefore, it is very important to develop a conductive agent material with good dispersibility, high conductivity and high stability. Summary of the Invention

[0004] The purpose of the present invention is to provide a novel one-dimensional material that can be used as a conductive agent: MXene nanorolls, which are MXene nanomaterials with a one-dimensional hollow roll structure.

[0005] The first aspect of the present invention provides the use of MXene nanorolls as a conductive agent.

[0006] The second aspect of the present invention provides a conductive agent, which includes the above-mentioned MXene nanorolls.

[0007] In some embodiments, the chemical formula of the above-mentioned MXene nanorolls is represented as M n+1 X n T x , where M is selected from one or more of 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 is a functional group.

[0008] In some embodiments, the above-mentioned transition metal elements include one, two or more of Ti, V, Nb, Cr, Ta, Hf, Mo, W, Fe, Mn, Y or Sc elements; and / or, T x is a functional group, and the functional group includes elements of Group VI and / or Group VII of the periodic table.

[0009] In some embodiments, the above-mentioned hollow scroll structure is formed by curling a two-dimensional MXene material; and / or, both ends of the MXene nanosroll are open; and / or, the one-dimensional structure of the MXene nanosroll is linear; and / or, the hollow scroll structure is formed by curling a single sheet and / or a single layer of two-dimensional MXene material.

[0010] In some embodiments, the thickness of the tube wall of the above-mentioned MXene nanosroll ranges from 0.3 nm to 50 nm; and / or, the length of the MXene nanosroll ranges from 0.1 μm to 100 μm; and / or, the tube diameter of the MXene nanosroll ranges from 10 nm to 200 nm.

[0011] In some embodiments, the above-mentioned conductive agent further includes a two-dimensional material; and / or, the above-mentioned conductive agent further includes a one-dimensional material; and / or, the above-mentioned conductive agent further includes a zero-dimensional material.

[0012] In some embodiments, the above-mentioned two-dimensional material is one or more of two-dimensional MXene material, graphene, and graphite flakes; the above-mentioned one-dimensional material is carbon nanotube and / or graphene roll; the above-mentioned zero-dimensional material is carbon black and / or metal nanoparticles.

[0013] The third aspect of the present invention provides a conductive paste, which includes the above-mentioned conductive agent and a solvent.

[0014] In some embodiments, the above-mentioned solvent is selected from one or more of water, N-methylpyrrolidone, N,N-dimethylformamide, ethanol, isopropanol, acetone, toluene or n-hexane; and / or, the mass content of the MXene nanosroll ranges from 0.001 wt.% to 90 wt.%; and / or, the conductive paste further includes a dispersant.

[0015] In some embodiments, the above-mentioned dispersant is selected from one or more of polytetrafluoroethylene, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol or sodium carboxymethylcellulose.

[0016] The fourth aspect of the present invention provides a method for preparing the above conductive paste, the steps including: dispersing a two-dimensional MXene material or an etched product with an accordion morphology obtained by etching a MAX phase material in a liquid phase containing a positive ion pair reagent, and forming a liquid phase flow under the action of an external force to obtain MXene nanorolls; mixing the above MXene nanorolls and the above solvent in a certain proportion to obtain a conductive paste.

[0017] In some embodiments, the above positive ion pair reagent is an alkyl quaternary ammonium compound; preferably, the above alkyl quaternary ammonium compound is selected from one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide or tetraamylammonium hydroxide; and / or, the liquid phase includes: one or more of water, ethanol, isopropanol; and / or, the action of the external force further includes: stirring, or, stirring and ultrasonic treatment; preferably, the above stirring is a directional rotation to form a directional liquid phase flow; and / or, the mass content of the positive ion pair reagent in the liquid phase is between 1 wt.% and 30 wt.%.

[0018] The fifth aspect of the present invention is an application of the above conductive agent, or, the above conductive paste in the fields of batteries, supercapacitors, printing and dyeing, conductive inks, and conductive inks.

[0019] The MXene nanorolls in the present invention belong to a change in the microstructure of the MXene material and still retain the conductive characteristics of the MXene material. However, in the present invention, this new type of MXene nanoroll is used as a conductive agent, not only utilizing its material conductive characteristics, but also combining its special one-dimensional hollow morphology. From the perspective of the use of the conductive agent, the material closest to the MXene nanorolls of the present invention is a typical one-dimensional material: carbon nanotubes. However, the MXene nanorolls of the present invention are significantly different from carbon nanotubes, as described below: Analyzing the morphology of the one-dimensional structure from the formation mechanism: Carbon nanotubes are grown at high temperature using a carbon source gas as a raw material under the action of a catalyst. Therefore, carbon nanotubes are composed of carbon atoms, showing a curved linear one-dimensional structure with closed ends; MXene nanorolls are formed by curling two-dimensional MXene materials and are composed of transition metal elements, non-metal elements (such as C, N, etc.) and surface functional groups, showing a linear one-dimensional structure and open ends at both ends. When used as a conductive agent, the beneficial technical effects of MXene nanorolls are as follows: 1. MXene nanorolls have a linear one-dimensional structure and are characterized by monodispersion without aggregation. Due to the intertwining of the microscopically curved one-dimensional structures, the aggregates of carbon nanotubes (powders or slurries) macroscopically exhibit easy aggregation and difficult dispersion. Usually, a large amount of dispersant needs to be added, but the addition of the dispersant will reduce the conductivity. However, for the linear one-dimensional structure of MXene nanorolls, their aggregates are in a monodispersed state, without aggregation and easy to disperse. Good dispersion effects can be achieved without adding a dispersant or only adding a small amount of dispersant, thereby improving the conductivity. Compared with carbon nanotubes, MXene nanorolls are also more easily and uniformly dispersed into the matrix.

[0020] 2. MXene nanorolls have the characteristics of being hollow inside and open at both ends. The liquid substances inside the hollow rolls can enter, enabling the simultaneous realization of the functions of solid-state electron conduction and liquid-state ion conduction. That is, the tube walls of MXene nanorolls achieve electron transfer, while the hollow interiors of MXene nanorolls are filled with liquid to achieve ion transfer. The two ends of carbon nanotubes are closed structures, making it difficult to achieve this function, which is very meaningful for applications in battery electrode materials.

[0021] 3. MXene nanorolls have excellent conductivity and hydrophilicity due to the presence of abundant hydrophilic functional groups on the surface, and are suitable for use in aqueous solvents. Carbon nanotubes are composed of carbon elements and do not have surface functional groups, showing hydrophobicity. When used in aqueous solvents, a dispersant needs to be added or the carbon nanotubes need to be modified, increasing the usage cost. As for the use as a conductive agent, the raw materials of aqueous solvents are easily obtained, with low cost and easy removal, which can reduce the usage cost and difficulty. Description of the Drawings

[0022] Figure 1 XRD spectra of the MAX phase material and two-dimensional MXene material in Example 1 of the present invention (a); SEM photos of the MAX phase material (b) and the etched products (c, d); Figure 2 SEM photos of the samples obtained in Example 1 of the present invention with the mass concentration of the cationic surfactant being 1 wt.%, 5 wt.%, 10 wt.%, 20 wt.% (a, b, c, d) and stirring applied; Figure 3 SEM photo of the sample obtained in Example 1 of the present invention with the mass concentration of the cationic surfactant being 20 wt.% but without stirring applied; Figure 4 TEM photos of the MXene nanorolls obtained in Example 1 of the present invention (a), and the statistical graph of the tube diameter distribution (b); Figure 5 TEM photos of the MXene nanorolls at different magnifications in Example 1 of the present invention (a and b), and HRTEM photos (c and d); Figure 6 Element distribution map of MXene nanorolls in Example 1 of the present invention; Figure 7 XRD spectra of MAX phase material and two-dimensional MXene material in Example 2 of the present invention (a); SEM photos of MAX phase material (b) and two-dimensional MXene material (c); Figure 8 TEM photos of MXene nanorolls obtained in Example 2 of the present invention (a), and statistical chart of tube diameter distribution (b); Figure 9 TEM photos of MXene nanorolls in Example 2 of the present invention (a), HRTEM photos at different magnifications (b and c), and element distribution photos (e~j); Figure 10 XRD spectra of MAX phase material and two-dimensional MXene material in Example 3 of the present invention (a); SEM photos of MAX phase material (b) and two-dimensional MXene material (c); Figure 11 SEM photos of 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); Figure 12 XRD spectra of V2AlC and V2CT x in Example 4 of the present invention (a), SEM photo of V2AlC (b), SEM (c), TEM (d), and HRTEM (e) photos of MXene nanorolls; Figure 13 Cycling performance test results of graphite electrode at a current density of 0.5C in Example 11 of the present invention (a) and capacity comparison chart after 60 cycles (b); Figure 14 Cycling performance comparison of graphite electrodes with different conductive agents added in Example 11 of the present invention. Detailed implementation manners

[0023] The technical solution of the present invention is illustrated by the following specific examples. It should be understood that one or more steps mentioned in the present invention do not exclude the existence of other methods and steps before and after the combined steps, or other methods and steps can be inserted between these explicitly mentioned steps. It should also be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. Unless otherwise specified, the numbers of each method step are only for the purpose of identifying each method step, rather than restricting the arrangement order of each method or limiting the implementation scope of the present invention. The change or adjustment of their relative relationship can also be regarded as the scope where the present invention can be implemented under the condition of no substantial change in technical content.

[0024] There are no specific restrictions on the sources of the raw materials and instruments used in the examples, and they can be purchased on the market or prepared by conventional methods well-known to those skilled in the art.

[0025] Example 1 This example provides an MXene nanocylinder with the chemical formula V2B 0.28 C 0.57 N 0.15 T x , and the specific steps of the preparation method are as follows: 1) Prepare two-dimensional MXene material from MAX phase material Etch the MAX phase material V2AlB 0.28 C 0.57 N 0.15 with an etchant at 90 °C for 48 h to obtain a mixed solution containing the etch product (5 mg / ml); wherein, the etchant is a mixed solution of concentrated hydrochloric acid (30 wt.%) and NaF, and the molar ratio of NaF to HCl is 1:1. The obtained etch product is a two-dimensional MXene material, labeled as: V2(B x C y N 1-x-y )T x ; After centrifuging and washing the above mixed solution containing the etch product, the obtained etch product is characterized. Figure 1 a shows the XRD comparison between the MAX phase material and the etch product. It can be seen that the (002) diffraction peak of the etch product shifts to a lower angle, and the characteristic peaks of other MAX phases disappear. This is because after the A component (Al element) in the MAX phase material is selectively etched, a two-dimensional MXene material is obtained, and the interlayer spacing between its flakes increases. It can be seen from the SEM photos that the MAX phase material presents a typical layered bulk morphology ( Figure 1 b); while the etch product presents an accordion-like morphology of flake stacking ( Figure 1 c and d), and the interlayer spacing increases significantly, which is consistent with the results of the previous XRD pattern. It can also be seen from Figure 1 c that in the etch product, the flake diameter of the flakes is about 1 μm to 10 μm, and most of the flake diameters are about 5 μm.

[0026] 2) Prepare MXene nanocylinder from two-dimensional MXene material Add the etch product obtained in step 1 above to an aqueous solution of 1 wt.% to 20 wt.% tetrabutylammonium hydroxide (TBAOH), stir magnetically (1500 r / min) for 5 min, then sonicate (1000 W) for 30 min, and centrifuge and wash multiple times to obtain a purified sample.

[0027] Figure 2SEM images of the samples obtained with the addition of 1 wt.%, 5 wt.%, 10 wt.%, and 20 wt.% of TBAOH are shown in a-d. It can be seen that when 1 wt.% of TBAOH was added, the edges of the two-dimensional MXene material showed a curled state ( Figure 2 a), and when the TBAOH concentration was increased to 5 wt.%, the curling of the edges of the two-dimensional MXene material became more obvious ( Figure 2 b). When the TBAOH concentration was further increased to 10 wt.%, most of the two-dimensional MXene materials in the sample showed a state of nanocurls ( Figure 2 c). When the TBAOH concentration increased to 20 wt.%, the two-dimensional MXene materials in the sample were completely transformed into MXene nanocurls ( Figure 2 d). Figure 2 a-d clearly show the process of gradually forming MXene nanocurls from the curling of two-dimensional MXene materials, and the one-dimensional hollow nanocurl structure formed by the curling of the edges of the same piece of two-dimensional MXene material. Figure 3 SEM images of the sample with the addition of 20 wt.% of TBAOH without stirring and ultrasonic treatment are shown. It can be seen that the sample shows a thin and flexible morphology without curling, indicating that external force is crucial for the formation of MXene nanocurls.

[0028] It can also be seen from the above examples that adding an appropriate amount of cation-pair reagent in the liquid phase has a significant effect on accelerating the formation of MXene nanotubes. For example, with 20 wt.% of TBAOH added, fully curled MXene nanocurls can be obtained with only 5 min of stirring and 10 min of ultrasonication. In contrast, with only 1 wt.% of TBAOH added, curling can occur under the same conditions, but the nanocurl structure cannot be formed, and the stirring time needs to be extended. This can be explained as follows: a higher concentration of cation-pair reagent will graft more alkyl chains on the surface of the two-dimensional MXene material. Under the same external force, a greater external force is generated, making it easier to quickly form a one-dimensional hollow curl structure. In the optimized experiment, the addition amount of the cation-pair reagent can be between 1 wt.% and 50 wt.%, and the optimal addition amount of the cation-pair reagent can be obtained through a limited number of experiments according to different types of MXene materials and the negative charge amount on the surface of the MXene material.

[0029] Stirring to generate a unidirectional flow in the liquid phase can provide a continuous and uniform external force for curling, which is important for obtaining a large amount and uniform MXene nanocurls. From the characterization results, the two-dimensional MXene material has almost completely transformed into MXene nanocurls, as shown in SEM (such as Figure 2 d) and TEM (such as Figure 6a) As shown in the photograph, that is to say, the present invention can macroscopically prepare uniform and monodisperse MXene nanorolls, which is of great significance for subsequent applications.

[0030] In some other embodiments, the cationic pair reagent can also be selected from one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetraamylammonium hydroxide. The difference between these reagents and TBAOH in this embodiment lies in the different lengths of the alkyl chains. It is reasonably predicted that the same technical effects can also be produced.

[0031] The obtained MXene nanorolls were tested by transmission electron microscopy (TEM). As Figure 4 shown in a), it can be seen that the MXene nanorolls have a significant one-dimensional morphology. The length of the MXene nanorolls ranges from 0.5 μm to 5 μm, corresponding to the sheet diameter of the two-dimensional MXene material before winding. Each MXene nanoroll is independently dispersed (monodisperse). Figure 4 b) Statistical analysis was performed on the tube diameter of the MXene nanorolls. It can be seen that the tube diameter of the nanotubes is between 20 nm and 80 nm, and the content of MXene nanotubes with a tube diameter of 40 nm is the highest, accounting for more than 40%.

[0032] Figure 5 a and b show TEM photographs of MXene nanorolls at different magnifications. It can be clearly seen that the MXene nanorolls have a hollow roll structure formed by curling a single sheet of two-dimensional MXene material, a straight one-dimensional morphology, an open end at the end, and a smooth tube wall. Through Figure 5 the high-resolution electron microscopy photographs (HRTEM) of c and d, it can be seen that the tube wall of the MXene nanorolls is only composed of 2 - 3 layers of MXene layers, and the layer spacing is 1.08 nm, that is, the thickness of the tube wall is only 3 nm - 4 nm, and the tube wall is ultrathin, indicating that the MXene nanorolls of the present invention are formed by curling a single layer of two-dimensional MXene material. Through Figure 5 d, it can also be seen that the tube wall of the MXene nanorolls shows the typical hexagonal lattice of MXene, indicating that the MXene nanorolls have a crystal structure.

[0033] Figure 6 The element distribution of the MXene nanorolls shown by the TEM test is given. It can be seen that the MXene nanorolls contain elements V, B, C, N, O, and F, and each element is evenly distributed. Among them, the elements O and F are the functional group elements on the surface of the MXene nanorolls, which match its chemical formula V2(B x C y N 1-x-y )T x match.

[0034] The present invention does not limit the source of the raw material MAX phase material, and the MAX phase material can be purchased commercially or prepared by high temperature sintering. 0.28 C 0.57 N 0.15 The MAX phase material is prepared by a high-temperature sintering method, comprising the following steps: sintering the simple substance or compound of each element at a high temperature according to the stoichiometric ratio of the elements in the chemical formula of the MAX phase material. In this embodiment, more specifically, vanadium powder (V), aluminum powder (Al), boron powder (B), carbon powder (C), and carbonized nitrogen (CN) are mixed at a molar ratio of 2:1:0.85:0.42:0.15 and ball-milled, and then placed in a high-temperature sintering furnace. After sintering at a high temperature of 1500°C for 24 hours under an argon atmosphere, the mixture is cooled to room temperature to obtain the MAX phase material.

[0035] In some embodiments, the etchant in step 1 can also be replaced by a 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 the accordion-shaped MXene material obtained by vapor phase etching.

[0036] Example 2 This embodiment provides another MXene nanoscroll, whose chemical formula is: V2C 0.5 N 0.5 T x , the preparation method comprises: 1) Preparation of two-dimensional MXene materials from MAX phase materials MAX phase material V2AlC 0.5 N 0.5 A mixture of concentrated hydrochloric acid (30 wt.%) and NaF, wherein the molar ratio of NaF to HCl is 1:1, was used for etching at 40 °C for 48 h. The etched product was a two-dimensional MXene material, labeled as: V2(C x N 1-x ) T x .

[0037] pass Figure 7 From the XRD comparison of a, it can be seen 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 product exhibits an accordion-like morphology of stacked flakes with significantly increased interlayer spacing, consistent with the previous XRD pattern results. The flake diameter ranges from approximately 5μm to 15μm.

[0038] 2) MXene nanorolls are obtained by curling two-dimensional MXene materials 1 g of the above etchant was added to an aqueous solution of 30 wt.% TBAOH (50 ml), and after magnetic stirring for 10 min, it was centrifuged and washed multiple times to obtain a purified sample. The TEM test results of the sample are as Figure 8 shown in a. It can be seen that the sample also exhibits a significant one-dimensional morphology. The length of the MXene nanorolls is more than 5 μm, corresponding to the sheet diameter of the two-dimensional MXene material before winding, indicating that the MXene nanorolls of the present invention are obtained by curling two-dimensional MXene sheets. Figure 8 b statistically analyzed the tube diameter of the MXene nanorolls. It can be seen that the tube diameter of the hollow rolls is between 20 nm and 140 nm, and the content of MXene nanotubes with a tube diameter of 60 nm is the highest, accounting for more than 30%.

[0039] Figure 9 From the TEM photo of a, it can be seen that the port of the MXene nanoroll is open. Figure 9 b and c are HRTEM photos. It can be seen that the MXene nanorolls have a hollow roll structure, and the tube wall is about 3 to 6 layers of MXene layers. Figure 9 e~j show the element distribution of the MXene nanorolls. It can be seen that the MXene nanorolls contain V, C, N, O, and F elements, and each element is evenly distributed. Among them, O and F elements are the functional group elements on the surface of the MXene nanorolls, which match its chemical formula V2(C x N 1-x )T x match.

[0040] The MAX phase material in this example is prepared by a high-temperature sintering method. The steps include: sintering the simple substances or compounds of each element according to the element stoichiometric ratio in the chemical formula of the MAX phase material. In this example, the preparation method of V2AlC 0.5 N 0.5 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, ball milling, placing it in a high-temperature sintering furnace, sintering at 1500 °C for 24 h under an argon atmosphere, and then cooling to room temperature to obtain.

[0041] Example 3 This example provides an MXene nanoroll with a chemical formula of Ti3CNT x , and the preparation method steps include: 1) Preparing two-dimensional MXene materials from MAX phase materials The MAX phase material Ti3AlCN was etched with a mixed solution of concentrated hydrochloric acid (30 wt.%) - LiF at 40 °C for 48 h. Among them, the molar ratio of LiF to HCl was 1:1 to obtain a two-dimensional MXene material labeled as Ti3CNT x .

[0042] Through Figure 11 XRD comparison of a shows that compared with the MAX phase material, the (002) diffraction peak of the etched product shifts to a lower angle, and the characteristic peaks of other MAX phases disappear. Figure 11 SEM photos of b and c show that the MAX phase material presents a typical layered bulk morphology; the etched product presents an accordion-like morphology of sheet stacking, and the layer spacing increases significantly. The sheet diameter is about 3 μm to 5 μm.

[0043] 2) MXene nanorolls are obtained by curling two-dimensional MXene materials The above-mentioned etched product was added to an aqueous solution of TBAOH with a mass concentration of 10 wt.%, magnetically stirred for 30 min, and then centrifuged and washed repeatedly to obtain a purified sample, and the obtained sample was obtained. Figure 11 SEM photos of the samples stirred for 1 min, 10 min, and 30 min are shown in a to c respectively. It can be seen that the two-dimensional MXene material gradually curls, and finally MXene nanorolls are obtained. The tube diameter of the MXene nanorolls is about 200 nm to 300 nm. It can be seen that the time of external force action also has an impact on the formation of MXene nanorolls. Under a lower concentration of positive ion pair reagent, prolonging the stirring time can also obtain MXene nanorolls.

[0044] Example 4 This example provides another MXene nanoroll used as a conductive component in a conductive paste, and its chemical formula is: V2CT x ; The preparation method includes: 1) The MAX phase material V2AlC was etched with a concentrated hydrochloric acid - NaF etchant at 90 °C for 48 h to obtain a two-dimensional MXene material - V2CT x ; 2) The above two-dimensional MXene material was added to an intercalating agent TBAOH solution with a mass concentration of 20 wt.%, magnetically stirred for 5 min, and then centrifuged, washed repeatedly, purified and dried to obtain MXene nanorolls; Figure 12 a shows the XRD spectra of V2AlC and V2CT x ; Figure 12 b shows the SEM photo of V2AlC, which can be seen as a bulk material; Figure 12 c and d show MXene nanorolls (V2CT xSEM and TEM images of ( ) show that the MXene nanorolls exhibit a monodisperse one-dimensional hollow nanoroll morphology, with a tube diameter ranging from 40 nm to 70 nm and a length ranging from 2 to 5 μm. Figure 12 Figure e shows the HRTEM image, indicating that the wall thickness of the MXene nanorolls is between 2 nm and 3 nm, featuring an ultrathin wall.

[0045] Using a similar method, the applicant 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 Cr 0.2 )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 N0.15 T x It can be seen that the preparation method of the present invention has a certain universality for two-dimensional MXene materials. The types of MXene nanoscrolls 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 nanoscroll structure of the present invention by adjusting the experimental methods and conditions.

[0046] Since the MXene nanoscroll of the present invention is formed by curling up two-dimensional MXene materials, the length of the MXene nanoscroll in one dimension is related to the sheet diameter of the two-dimensional MXene material. For two-dimensional MXene materials, the sheet diameter can be distributed between 0.1μm and 100μm. Therefore, we can reasonably predict that the length of the MXene nanoscroll can also be within this range.

[0047] The above Examples 1 to 4 give details of the preparation method, morphology and structural characteristics of the MXene nanoscrolls of the present invention. In order to illustrate the conductive properties of the MXene nanoscrolls of the present invention as a conductive agent, the etched material obtained in the above examples was centrifuged and cleaned, dispersed in a solvent for ultrasonic dispersion, and then freeze-dried to obtain a powder of the two-dimensional MXene material. A more specific step is to disperse the etched material in water (2 mg / ml) and then ultrasonically treat it for 12 hours, and then freeze-dry it; the prepared MXene nanoscroll dispersion was centrifuged and concentrated, and then freeze-dried to obtain MXene nanoscroll powder. The conductivity of the two powders was tested using the four-probe method. The test method is as follows: 50 mg of powder sample is added to the sample tank of the four-probe powder resistance meter, flattened, and then the four-probe powder resistance meter is turned on. The handle is rotated to move the upper probe of the resistance meter downward, and then the pressure is applied to 15 MPa. After the powder resistance meter reading stabilizes, the resistivity reading is read, and then the conductivity is obtained according to the conversion relationship of conductivity = 1 / resistivity. The results are shown in the following table:

[0048] It can be seen that in the powder state, the MXene nanoscroll of the present invention has an order of magnitude higher conductivity than the two-dimensional MXene material. This is because, on the one hand, the MXene nanoscroll has a one-dimensional structure and better directional conductivity; on the other hand, the MXene nanoscroll is a one-dimensional network-like overlap method, and its contact resistance is significantly lower than that of the two-dimensional MXene material, which belongs to the sheet overlap method. The MXene nanoscroll of the present invention has excellent conductivity as a conductive agent. Using the same method, carbon nanotube powder was tested and its conductivity was less than 100 S cm -1 , which is significantly lower than the MXene nanoscroll of the present invention. This can be explained by the fact that the conductivity of MXene materials is better due to the carbon nanotube materials. In addition, the monodisperse structure can reduce the contact resistance and the linear one-dimensional structure has better directional electron conduction.

[0049] Example 5 This example provides an aqueous conductive paste. The MXene nanorolls of the present invention are mixed with an aqueous solvent. Since the MXene nanorolls of the present invention are only a change in the microscopic morphology of the MXene material and still retain some properties of the MXene material, such as hydrophilicity, the MXene nanorolls can be fully dispersed in the aqueous solvent to obtain an aqueous MXene nanoroll conductive paste. The aqueous solvent can be pure water; it can also be a mixed solution of water and compounds such as alcohols, aldehydes, ketones, and ethers.

[0050]

[0050] In some preferred embodiments, a certain amount of MXene nanorolls is mixed with deionized water to prepare an MXene nanoroll conductive paste with a concentration ranging from 0.01 wt.% to 90 wt.%, preferably from 5 wt.% to 50 wt.%; more preferably from 20 wt.% to 30 wt.%.

[0051]

[0051] The conductive paste of the MXene nanorolls of the present invention has the characteristic of monodispersion. When the conductive component is only MXene nanorolls, no additional dispersant needs to be added, and it can be dispersed by stirring or ultrasonic treatment, with the characteristics of non-agglomeration and easy dispersion. However, the conductive paste of the present invention does not exclude the addition of other types of conductive agents, and a small amount of dispersant or other functional components can also be added according to application needs.

[0052] Example 6 This example provides a conductive paste, in which the conductive agent includes the MXene nanorolls of the present invention and two-dimensional materials. The two-dimensional material can be graphene or two-dimensional MXene materials. The MXene nanorolls of the present invention belong to typical one-dimensional materials. When two-dimensional materials are added to obtain a composite conductive paste, the beneficial effect is that a "plane-line-point" type conductive network can be formed. Compared with the conductive paste with a single-component conductive agent, under the condition of the same mass content of the conductive agent, the conductive paste with a composite-component conductive agent has better conductive performance, thereby improving the conductivity of the material; under the condition of the same conductive performance, the mass content of the composite-component conductive agent in the conductive paste is lower, which can save more costs.

[0053]

[0053] In some specific embodiments, the conductive agent MXene nanorolls and conductive graphene are mixed in a mass ratio of 1: (0.1 - 10) and added to a mixed solution of solvent water and ethylene glycol, wherein the volume ratio of water:ethylene glycol = 1: (0.1 - 5) to obtain a composite conductive paste.

[0054]

[0054] In a specific preferred embodiment, the mass fraction of the conductive agent ranges from 0.1 wt.% to 20 wt.%; In a specific preferred embodiment, the mass ratio of MXene nanorolls to conductive graphene is 1:(1 - 3); more preferably 1:1; the volume ratio of water to ethylene glycol is between 1:(0.5 - 3), and more preferably between 1:(0.8 - 1.5).

[0055] In some other embodiments, the above-mentioned conductive graphene can also be replaced by a two-dimensional MXene material; the above-mentioned ethylene glycol can also be replaced by other alcohols, such as ethanol, propanol, isopropanol, butanol, etc.

[0056] Example 7 This example provides a composite conductive paste. Specifically, it is a silver-aluminum paste containing MXene nanorolls, and the conductive components include metal silver powder, aluminum powder, and MXene nanorolls.

[0057] In one of the embodiments, by weight, the composite conductive paste contains 30 - 80 parts of metal powder (including silver powder or aluminum powder), 1 - 20 parts of MXene nanorolls, 10 - 40 parts of organic carrier, 5 - 10 parts of dispersant, 3 - 10 parts of surfactant, and 2 - 10 parts of defoamer; among them, the mass ratio of silver powder to aluminum powder is between 2:8 and 8:2.

[0058] In some embodiments, the particle size of the silver powder is selected to be 1 - 10 μm, and the particle size of the aluminum powder is 3 - 10 μm; the organic carrier is obtained by mixing resin and organic solvent in a mass ratio of 10∶90 - 46∶54, and the resin is selected from one or more of polyurethane resin, acrylic resin, and epoxy resin; the organic solvent is selected from one or more of ethylene glycol ethyl ether acetate, ethyl acetate, and methyl isobutyl ketone; the dispersant is phosphoric acid triester, 1,4-dihydroxy sulfonamide, or silicone oil; the defoamer is sodium dodecyl sulfonate, 2-methyl-4-ethylimidazole, or vinyl diphenylmethane; the surfactant is polyvinylpyrrolidone, glycerol monolactate, or triglycerol ethylenediamine carboxylate.

[0059] In a specific embodiment, the steps include: mixing acrylic resin and ethylene glycol ethyl ether acetate in a ratio of 40:50, and heating at a constant temperature of 70 °C until completely dissolved; then taking 10 g of flaky silver powder, 30 g of aluminum powder, 10 g of MXene nanorolls, and 10 g of organic carrier, and performing preliminary mixing in a blender, and then adding 5 g of 1,4-dihydroxy sulfonamide, 5 g of 2-methyl-4-ethylimidazole, and 5 g of triglycerol ethylenediamine carboxylate to the blender in sequence and mixing for 60 min to obtain the composite conductive paste.

[0060] The steps of the embodiment include: mixing a resin with an organic solvent to obtain an organic carrier, then adding a mixture of metal powder and MXene nanorolls to the organic carrier, and adding a dispersant, an antifoaming agent, a surfactant, etc., and obtaining the product after sufficient dispersion.

[0061] This embodiment provides an embodiment in which the conductive component is zero-dimensional metal powder and MXene nanorolls. Among them, one-dimensional MXene nanorolls can form a conductive network in zero-dimensional metal particles, enhancing the conductivity. The metal powder in this embodiment can also be replaced by one or more of other metals such as silver powder, aluminum powder, gold powder, copper powder, etc.

[0062] Example 8 This embodiment provides an organic solvent conductive paste and a preparation method thereof, including the steps: 1. Take a certain amount of the dispersant polyvinylidene fluoride (PVDF) and add it to the organic solvent N-methylpyrrolidone (NMP), and then stir at a rotation speed of 600 rpm for 2 h to 6 h until the solution becomes a uniform transparent liquid; 2. Take a certain amount of MXene nanorolls and add them to the above-mentioned uniformly stirred and dispersed liquid, and then apply a stirring and dispersion rotation speed of 450 rpm to obtain an organic conductive paste containing MXene nanorolls. Similarly, a conductive paste of carbon nanotubes is obtained by the same method.

[0063] In a preferred embodiment, the addition amount of the dispersant polyvinylidene fluoride (PVDF) is 1 wt.% to 5 wt.%, which is used to promote the dispersion of the conductive component; The addition amount of MXene nanorolls is not limited and can be between 0.001 wt.% and 99 wt.%; preferably, the addition amount is 20 wt.% to 50 wt.%; more preferably, it is 30 wt.% to 40 wt.% to form a better viscous paste.

[0064] The organic solvent in the conductive paste of the present invention can also be selected from one or more of N-methylpyrrolidone, N,N-dimethylformamide, acetone, toluene or n-hexane; the dispersant is selected from one or more of polytetrafluoroethylene, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol or sodium carboxymethylcellulose.

[0065] Example 9 This embodiment uses the method in the above-mentioned Example 8, and the MXene nanorolls selected are V2CT xNanotubes, where 2 wt.% of the dispersant PVDF was added in Step 1; in Step 2, a certain amount of MXene nanotubes was added to obtain conductive pastes with mass fractions of MXene nanotubes of 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% respectively; preferably, when the mass fraction is 30% - 50%, the conductive paste exhibits more suitable viscosity properties.

[0066] Using the same method, replace the MXene nanotubes in this example with carbon nanotubes (purchased) to obtain a comparative carbon nanotube conductive paste.

[0067] Example 10 This example provides an application of the conductive paste of the present invention in the battery field, more specifically, an electrode sheet containing the conductive paste of the present invention. The method for manufacturing the electrode sheet includes: Mix the electrochemically active material, conductive agent, and binder, and press them into a dry electrode; taking silicon as the electrochemically active material, in a specific embodiment, it includes: more specifically, the implementation steps are: mix silicon powder, MXene nanotubes, and PVDF according to a mass ratio of 7:1.5:1.5; then load the mixed powder into a powder feeder, and use a dry spraying machine to spray the powder onto a copper foil. After dry spraying, keep it at a constant temperature of 175 °C (because the melting point of PVDF is 155 - 160 °C) and perform hot pressing to obtain a composite material of silicon and MXene nanotubes. [[ID=1,2]]

[0068] Example 11 To illustrate the technical effects of MXene nanotubes in the electrode sheet compared with other types of conductive agents, and further to measure the influence of MXene nanotube materials on the electrode performance with different loadings (thicknesses), this example provides a comparison of MXene nanotubes with MXene nanosheets, Ketjenblack, graphene, carbon nanotubes (CNTs), and other conductive materials for graphite electrodes. Among them, the MXene nanotubes selected in Example 4 are V2CT x MXene nanotubes.

[0069] The preparation methods of the electrode and the battery are as follows: Mix graphite, MXene nanotubes, and PVDF according to a mass ratio of 90:5:5, add NMP to make a paste, and then use a scraper with different heights to scrape coatings on the copper foil to obtain electrodes with loadings of 4, 6, 8, and 10 mg / cm 2 Load electrodes, and then dry them in vacuum to obtain the electrodes. Assemble the electrode sheets into a full battery according to the sequence of negative electrode case - negative electrode - separator - electrolyte - lithium sheet - gasket - spring sheet - positive electrode case, and perform a cycling test at a current density of 0.5C. Using the same method, replace the MXene nanotubes with Ketjenblack, carbon nanotubes (CNT), and graphene to obtain comparative electrodes and comparative batteries.

[0070] As Figure 13 shown, the cycling performance tests of each electrode with a loading of 4 mg / cm 2 were carried out at a current density of 0.5C. It can be seen that the electrode containing MXene nanorolls exhibits the best cycling capacity, remaining at 312.2 mAh / g even at the 60th cycle, which is higher than the capacities of the current conductive agents such as Ketjen black, CNTs, graphene, and MXene nanosheets used as additives. This shows that adding MXene nanorolls to the electrode can improve the capacity of the electrode material.

[0071] As Figure 14 shown in a~c, the cycling performance graphs of MXene nanorolls, Ketjen black, and carbon nanotubes (CNTs) as conductive agents at different loadings are given respectively. It can be seen that the MXene nanoroll material has a higher capacity and better cycling stability than Ketjen black and CNT at the same loading (thickness). In addition, as the loading (thickness) increases, due to its good conductivity and high uniformity, the MXene nanorolls improve the electrochemical performance of the high-loading electrodes. Even when the loading reaches 10 mg / cm 2 , its electrochemical performance is still excellent. However, for the two materials of Ketjen black and CNT, as the loading increases, the battery capacity significantly decays. This demonstrates the promoting effect of MXene nanorolls on the application of thick electrodes.

[0072] The above-mentioned technical effects were verified through laboratory coin cells. For the electrode sheet, the loading of the active material in the electrode sheet can be further increased through process optimization, so that the loading is between 10 mg / cm 2 or above, thereby increasing the energy and volumetric density of the battery. For different electrochemical substances, there may be different optimal loadings, which can be obtained through limited optimizations.

[0073] The above gives an application method of the conductive paste of the present invention in the battery field. The conductive paste of the present invention can also be applied to other energy storage devices, such as lead-acid batteries, supercapacitors, sensing, photovoltaic cells, and other application scenarios that require conductivity.

[0074] The foregoing description of the specific exemplary embodiments of the present invention is for purposes of illustration and exemplification. These descriptions are not intended to limit the invention to the precise forms disclosed, and obviously, many changes and variations are possible in light of the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical applications, so that those skilled in the art can implement and utilize various different exemplary embodiments of the invention as well as various different selections and changes. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A composite conductive paste, characterized in that, The conductive components in the composite conductive paste include: metal powder, MXene nanorolls; the MXene nanorolls are MXene materials with a one-dimensional hollow roll structure; the hollow roll structure is formed by curling a single sheet and / or monolayer of two-dimensional MXene material.

2. The composite conductive paste according to claim 1, wherein The metal powder is selected from one or more of silver powder, aluminum powder, gold powder, and copper powder; And / or, the composite conductive paste contains functional additives, including: one or more of a dispersant, an antifoaming agent, and a surfactant; preferably, the dispersant is selected from: phosphate triester, 1,4-dihydroxy sulfamic acid amine, or silicone oil; the antifoaming agent is sodium dodecyl sulfonate, 2-methyl-4-ethylimidazole, or vinyl diphenylmethane; the surfactant is polyvinylpyrrolidone, monoglyceride lactate, or triglyceryl ethylenediamine carboxylate; And / or, the composite conductive paste further includes an organic carrier, which is obtained by mixing a resin and an organic solvent; preferably, the resin is selected from one or several of polyurethane resin, acrylic resin, and epoxy resin; the organic solvent is selected from one or several of ethylene glycol monoethyl ether acetate, ethyl acetate, and methyl isobutyl ketone; more preferably, the mass ratio of the resin to the organic solvent is between 10:90 and 46:

54.

3. The composite conductive paste according to claim 2, wherein In the composite conductive paste, by weight, it contains 30-80 parts of metal powder, 1-20 parts of MXene nanorolls, 10-40 parts of organic carrier, 5-10 parts of dispersant, 3-10 parts of surfactant, and 2-10 parts of antifoaming agent; Preferably, the metal powder is silver powder and aluminum powder; More preferably, the mass ratio of the silver powder to the aluminum powder is between 2:8 and 8:

2.

4. The composite conductive paste according to any one of claims 1 to 3, characterized in that The thickness of the tube wall of the MXene nanorolls is between 0.3 nm and 50 nm; the tube diameter of the MXene nanorolls is between 10 nm and 200 nm; And / or, the one-dimensional structure of the MXene nanorolls is linear; And / or, the length of the MXene nanorolls is between 0.1 μm and 100 μm; And / or, the two ends of the MXene nanorolls are open; And / or, the chemical formula of the MXene nanocylinder is expressed as V2B 0.28 C 0.57 N 0.15 T x , V2C 0.5 N 0.5 T x , Ti3CNT x , V2CT x , Ti2CT x , Ti3C2T x , Nb2CT x , TiNbCT x , Cr2CT x , Ti3CNT x , Ti2C 0.5 N 0.5 T x , Ti 0.5 V 0.5 C 0.5 N 0.5 T x , V2C 0.75 N 0.25 T x , (V 0.8 Cr 0.2 )2B 0.33 C 0.67 T x , (V 0.8 Cr 0.2 )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 ; And / or, the preparation method of the MXene nanorolls includes: dispersing two-dimensional MXene material or the accordion-shaped etchant obtained by etching MAX phase material in a liquid phase containing a positive ion pair reagent, and forming a liquid phase flow under the action of an external force to obtain the MXene nanorolls.

5. A preparation method of a composite conductive paste as described in any one of claims 1 to 4, characterized in that the steps Including: Mixing a resin and an organic solvent to obtain an organic carrier, and then adding a mixture of metal powder and MXene nanorolls to the organic carrier and dispersing; Preferably, the step further includes: adding a dispersant, an antifoaming agent, and a surfactant during the dispersion process.

6. A composite conductive paste, characterized in that, The conductive components of the composite conductive paste include: two-dimensional material, MXene nanorolls; the two-dimensional material is graphene or two-dimensional MXene material; the MXene nanorolls are MXene materials with a one-dimensional hollow roll structure; the hollow roll structure is formed by curling a single sheet and / or monolayer of two-dimensional MXene material. Preferably, the mass ratio of the MXene nanocylinder to the two-dimensional material is 1:(0.1~10); more preferably, 1:(1~3); still more preferably, 1:1; and / or, the mass fraction of the conductive component is between 0.1wt.% and 20wt.%; and / or, the solvent is a mixed solution of water and alcohols. Preferably, the alcohols are ethylene glycol, ethanol, propanol, isopropanol, butanol; more preferably, the volume ratio of water to alcohols is between 1:(0.1~5), still more preferably, between 1:(0.5~3); more preferably, between 1:(0.8~1.5).

7. The composite conductive paste according to claim 6, wherein The thickness of the tube wall of the MXene nanocylinder is between 0.3 nm and 50 nm; the tube diameter of the MXene nanocylinder is between 10 nm and 200 nm; and / or, the one-dimensional structure of the MXene nanocylinder is linear; and / or, the length of the MXene nanocylinder is between 0.1 μm and 100 μm; and / or, both ends of the MXene nanocylinder are open; And / or, the chemical formula of the MXene nanoroll is expressed as V2B 0.28 C 0.57 N 0.15 T x 、V2C 0.5 N 0.5 T x 、Ti3CNT x 、V2CT x 、Ti2CT x 、Ti3C2T x 、Nb2CT x 、TiNbCT x 、Cr2CT x 、Ti3CNT x 、Ti2C 0.5 N 0.5 T x 、Ti 0.5 V 0.5 C 0.5 N 0.5 T x 、V2C 0.75 N 0.25 T x 、(V 0.8 Cr 0.2 )2B 0.33 C 0.67 T x 、(V 0.8 Cr 0.2 )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 ; and / or, the preparation method of the MXene nanocylinder includes: dispersing two-dimensional MXene materials or the accordion-shaped etching products obtained by etching MAX phase materials in a liquid phase containing a positive ion pair reagent, and forming liquid phase flow under the action of external force to obtain the MXene nanocylinder.

8. A method for preparing a composite conductive paste as described in claim 6 or 7, characterized in that, The steps include: Obtained by mixing the MXene nanocylinder and the two-dimensional material in a certain mass ratio and adding them to a solvent.

9. A conductive paste, characterized in that, The conductive paste is composed of MXene nanocylinders and a solvent, and does not contain a dispersant; the MXene nanocylinder is a MXene material with a one-dimensional hollow cylinder structure; the hollow cylinder structure is formed by curling single-piece and / or single-layer two-dimensional MXene materials; preferably, the solvent is an aqueous solvent; more preferably, the aqueous solvent is water, or a mixed solution of water and alcohols, aldehydes, ketones, and ether compounds.

10. The conductive paste according to claim 9, wherein The thickness of the tube wall of the MXene nanocylinder is between 0.3 nm and 50 nm; the tube diameter of the MXene nanocylinder is between 10 nm and 200 nm; and / or, the one-dimensional structure of the MXene nanocylinder is linear; and / or, the length of the MXene nanocylinder is between 0.1 μm and 100 μm; and / or, both ends of the MXene nanocylinder are open; And / or, the chemical formula of the MXene nanoroll is expressed as V2B 0.28 C 0.57 N 0.15 T x 、V2C 0.5 N 0.5 T x 、Ti3CNT x 、V2CT x 、Ti2CT x 、Ti3C2T x 、Nb2CT x 、TiNbCT x 、Cr2CT x 、Ti3CNT x 、Ti2C 0.5 N 0.5 T x 、Ti 0.5 V 0.5 C 0.5 N 0.5 T x 、V2C 0.75 N 0.25 T x 、(V 0.8 Cr 0.2 )2B 0.33 C 0.67 T x 、(V 0.8 Cr 0.2 )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 among others; and / or, the preparation method of the MXene nanocylinder includes: dispersing two-dimensional MXene materials or the accordion-shaped etching products obtained by etching MAX phase materials in a liquid phase containing a positive ion pair reagent, and forming liquid phase flow under the action of external force to obtain the MXene nanocylinder; and / or, the mass concentration of MXene nanocylinders in the conductive paste is between 0.001wt.% and 99wt.%; more preferably, between 5wt.% and 50wt.%; still more preferably, between 20wt.% and 30wt.%.

11. An organic solvent-based conductive paste, characterized in that, It includes MXene nanocylinders, a dispersant, and an organic solvent; the MXene nanocylinder is a MXene material with a one-dimensional hollow cylinder structure; the hollow cylinder structure is formed by curling single-piece and / or single-layer two-dimensional MXene materials.

12. The organic solvent-based conductive paste according to claim 11, wherein, The thickness of the tube wall of the MXene nanocylinder ranges from 0.3 nm to 50 nm; the tube diameter of the MXene nanocylinder ranges from 10 nm to 200 nm; and / or, the one-dimensional structure of the MXene nanocylinder is linear; and / or, the length of the MXene nanocylinder ranges from 0.1 μm to 100 μm; and / or, both ends of the MXene nanocylinder are open; And / or, the chemical formula of the MXene nanoroll is expressed as V2B 0.28 C 0.57 N 0.15 T x 、V2C 0.5 N 0.5 T x 、Ti3CNT x 、V2CT x 、Ti2CT x 、Ti3C2T x 、Nb2CT x 、TiNbCT x 、Cr2CT x 、Ti3CNT x 、Ti2C 0.5 N 0.5 T x 、Ti 0.5 V 0.5 C 0.5 N 0.5 T x 、V2C 0.75 N 0.25 T x 、(V 0.8 Cr 0.2 )2B 0.33 C 0.67 T x 、(V 0.8 Cr 0.2 )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 one of the following; and / or, the preparation method of the MXene nanocylinder includes: dispersing a two-dimensional MXene material or an etched product with an accordion morphology obtained by etching a MAX phase material in a liquid phase containing a positive ion pair reagent, and forming a liquid flow under the action of an external force to obtain the MXene nanocylinder; and / or, the addition amount of the MXene nanocylinder ranges from 0.001 wt.% to 99 wt.%; more preferably, it ranges from 20 wt.% to 50 wt.%; still more preferably, it ranges from 30 wt.% to 40 wt.%; and / or, the solvent is selected from one or more of N-methylpyrrolidone, N,N-dimethylformamide, acetone, toluene or n-hexane; the dispersant is selected from one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol or sodium carboxymethylcellulose.

13. A method for preparing an organic solvent-based conductive paste as described in claim 11 or 12, characterized in that, First, add the dispersant to the organic solvent and stir to disperse; then add the MXene nanocylinder and stir to disperse.

14. An electrode sheet, characterized in that, It contains an electrochemically active material, a conductive agent and a binder, and the conductive agent contains MXene nanocylinders; the MXene nanocylinders are MXene materials with a one-dimensional hollow cylinder structure; The hollow cylinder structure is formed by curling a single sheet and / or a single layer of two-dimensional MXene material; preferably, the electrochemically active material is silicon or graphite.

15. The electrode sheet according to claim 14, wherein, The thickness of the tube wall of the MXene nanocylinder ranges from 0.3 nm to 50 nm; the tube diameter of the MXene nanocylinder ranges from 10 nm to 200 nm; and / or, the one-dimensional structure of the MXene nanocylinder is linear; and / or, the length of the MXene nanocylinder ranges from 0.1 μm to 100 μm; and / or, both ends of the MXene nanocylinder are open; And / or, the chemical formula of the MXene nanoroll is expressed as V2B 0.28 C 0.57 N 0.15 T x 、V2C 0.5 N 0.5 T x 、Ti3CNT x 、V2CT x [[ID=I18]]、Ti2CT x 、Ti3C2T x 、Nb2CT x 、TiNbCT x 、Cr2CT x 、Ti3CNT x 、Ti2C 0.5 N 0.5 T x 、Ti 0.5 V 0.5 C 0.5 N 0.5 T x 、V2C 0.75 N 0.25 T x 、(V 0.8 Cr 0.2 )2B 0.33 C 0.67 T x 、(V 0.8 Cr 0.2 )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 among others; and / or, the preparation method of the MXene nanocylinder includes: dispersing a two-dimensional MXene material or an etched product with an accordion morphology obtained by etching a MAX phase material in a liquid phase containing a positive ion pair reagent, and forming a liquid flow under the action of an external force to obtain the MXene nanocylinder; And / or, the loading amount of the electrochemically active material in the electrode sheet ≥ 4 mg / cm 2 , more preferably, ≥ 6 mg / cm 2 ; still more preferably, ≥ 8 mg / cm 2 ; more preferably, ≥ 10 mg / cm 2 .

16. A method for preparing an electrode sheet as described in claim 14 or 15, characterized in that the steps including: mixing the electrochemically active material, the conductive agent and the binder, and pressing and forming to obtain; or, mixing the electrochemically active material, the conductive agent, the binder and the solvent to prepare a slurry, then scraping and coating to form a film, and drying to obtain.

17. A battery, characterized in that, It contains an electrode sheet as described in claim 14 or 15, or an electrode sheet obtained by the preparation method described in claim 16.

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