Conductive agent, conductive paste, preparation method and use thereof

Abstract

The present invention discloses a conductive agent, a conductive paste, a preparation method and uses thereof. The conductive agent includes MXene nanorolls, and the MXene nanorolls are MXene materials with a one-dimensional hollow roll structure. Belonging to the change in the microstructure of MXene materials, it still retains the conductive properties of MXene materials. For the use as a conductive agent, its aggregates are in a monodisperse state, with the effects of non-agglomeration and easy dispersion, and also have the characteristics of good directional conductivity and low contact resistance. Its conductivity is significantly higher than that of two-dimensional MXene materials, and it can be used as a substitute material to replace carbon nanotubes.

Description

Technical Field

[0001] The present invention belongs to the field of conductive materials, and in particular relates to a conductive agent containing MXene nanoscrolls, a conductive slurry, and a preparation method and use thereof. Background Art

[0002] At present, the conductive pastes that people have studied more are mixtures of graphene, carbon nanotubes, nanoparticles such as Ag, Au, Pd, Cu, and epoxy resin. First of all, the conductive pastes such as precious metal powder-epoxy resin are limited in large-scale use due to their high cost and complex production process; graphene and carbon nanotubes are carbon materials with ultra-high conductivity and chemical stability. During the mixing process, graphene and active materials are in "surface-point" contact, carbon nanotubes and active materials are in "line-point" contact, and graphene and carbon nanotube composite conductive pastes can achieve surface-line-point contact, which greatly improves the overall electrode performance and reduces the use of conductive agents in the electrode, thereby increasing the overall capacity of the battery. However, due to the strong van der Waals force and high specific surface area, graphene and carbon nanotubes are easy to agglomerate and stack seriously in the conductive paste, which greatly limits 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

[0003] The object of the present invention is to provide a new one-dimensional material that can be used as a conductive agent: MXene nanoscroll, which is a MXene nanomaterial with a one-dimensional hollow scroll structure.

[0004] A first aspect of the present invention provides a use of a MXene nanoscroll as a conductive agent.

[0005] A second aspect of the present invention provides a conductive agent, which includes: the above-mentioned MXene nanoscroll.

[0006] In some embodiments, the chemical formula of the MXene nanoscroll is represented by M n+1 X n T x , wherein, 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, T x For functional groups.

[0007] In some embodiments, the transition metal element includes: one, two or more of Ti, V, Nb, Cr, Ta, Hf, Mo, W, Fe, Mn, Y or Sc; and / or T x is a functional group, and the functional group includes: an element of the sixth main group and / or the seventh main group.

[0008] In some embodiments, the hollow roll structure is formed by curling a two-dimensional MXene material; and / or, both ends of the MXene nanoroll are open; and / or, the one-dimensional structure of the MXene nanoroll is linear; and / or, the hollow roll structure is formed by curling a single sheet and / or a single layer of two-dimensional MXene material.

[0009] In some embodiments, the thickness of the tube wall of the MXene nanoscroll is between 0.3 nm and 50 nm; and / or, the length of the MXene nanoscroll is between 0.1 μm and 100 μm; and / or, the tube diameter of the MXene nanoscroll is between 10 nm and 200 nm.

[0010] In some embodiments, the conductive agent further includes a two-dimensional material; and / or, the conductive agent further includes a one-dimensional material; and / or, the conductive agent further includes a zero-dimensional material.

[0011] In some embodiments, the two-dimensional material is one or more of two-dimensional MXene materials, graphene, and graphite sheets; the one-dimensional material is carbon nanotubes and / or graphene rolls; and the zero-dimensional material is carbon black and / or metal nanoparticles.

[0012] A third aspect of the present invention provides a conductive paste comprising the above-mentioned conductive agent and a solvent.

[0013] In some embodiments, the 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 nanoscroll is between 0.001wt.% and 90wt.%; and / or the conductive paste also includes a dispersant.

[0014] In some embodiments, the dispersant is selected from one or more of polytetrafluoroethylene, polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol or sodium carboxymethyl cellulose.

[0015] The fourth aspect of the present invention provides a method for preparing the above-mentioned conductive paste, the steps comprising: dispersing the two-dimensional MXene material or the accordion-shaped etching product obtained by etching the MAX phase material in a liquid phase containing a positive ion pair reagent, forming a liquid phase flow under the action of an external force, and obtaining a MXene nanoscroll; mixing the above-mentioned MXene nanoscroll and the above-mentioned solvent in a certain proportion to obtain a conductive paste.

[0016] In some embodiments, the above-mentioned positive ion pair reagent is an alkyl quaternary ammonium compound; preferably, the above-mentioned alkyl quaternary ammonium compound is selected from one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide or tetrapentylammonium hydroxide; and / or, the liquid phase includes: one or more of water, ethanol, isopropanol; and / or, the external force also includes: stirring, or stirring and ultrasound; preferably, the above-mentioned 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 1wt.% and 30wt.%.

[0017] A fifth aspect of the present invention is an application of the above-mentioned conductive agent or the above-mentioned conductive paste in the fields of batteries, supercapacitors, printing and dyeing, conductive ink, and conductive printing ink.

[0018] The MXene nanoscroll in the present invention is a microstructural change of the MXene material, and still retains the conductive properties of the MXene material. However, the present invention uses this new type of MXene nanoscroll as a conductive agent, which not only utilizes the conductive properties of the material, but also combines its special one-dimensional hollow morphology. From the perspective of the use of conductive agents, the material most similar to the MXene nanoscroll of the present invention is a typical one-dimensional material: carbon nanotubes. However, the MXene nanoscroll of the present invention is significantly different from carbon nanotubes, as explained below:

[0019] Analyzing the morphology of the one-dimensional structure from the formation mechanism: carbon nanotubes are grown at high temperature with carbon source gas as raw material under the action of catalysts. Therefore, carbon nanotubes are composed of carbon atoms, showing a curved linear one-dimensional structure with closed ends; MXene nanoscrolls are formed by the curling of two-dimensional MXene materials, composed of transition metal elements and non-metallic elements (C, N, etc.) and surface functional groups, showing a linear one-dimensional structure and the characteristics of opening at both ends. When used as a conductive agent, the beneficial technical effects of MXene nanoscrolls are:

[0020] 1.MXene nanoscrolls have a linear one-dimensional structure and are monodisperse and non-agglomerated. Due to the intertwining of the curved one-dimensional structures at the microscopic level, the aggregates (powder or slurry) of carbon nanotubes are easy to agglomerate and difficult to disperse at the macroscopic level, and usually require the addition of a large amount of dispersant, which in turn reduces the conductivity. However, the linear one-dimensional structure of MXene nanoscrolls has a monodisperse aggregate state, which is non-agglomerated and easy to disperse. Good dispersion effects can be achieved without adding dispersants or with only a small amount of dispersants, thereby improving the conductivity. Compared with carbon nanotubes, MXene nanoscrolls are also easier to disperse evenly in the matrix.

[0021] 2.MXene nanoscrolls are hollow inside and open at both ends. Liquid substances can enter the interior of the hollow scroll, and can simultaneously realize the functions of solid-state electron conduction and liquid ion conduction. That is, the tube wall of the MXene nanoscroll realizes the transfer of electrons, while the hollow scroll of the MXene nanoscroll is filled with liquid to realize the transfer of ions. The two ends of carbon nanotubes are closed structures, and it is difficult to achieve this function. This is very meaningful for its application in battery electrode materials.

[0022] 3.MXene nanoscrolls have excellent electrical conductivity and are hydrophilic due to the presence of abundant hydrophilic functional groups on the surface, making them suitable for use in aqueous solvents. However, carbon nanotubes are composed of carbon elements and have no surface functional groups, so they are hydrophobic. When used in aqueous solvents, dispersants need to be added or the carbon nanotubes need to be modified, which increases the cost of use. As a conductive agent, aqueous solvent raw materials are easy to obtain, low cost, and easy to remove, which can reduce the cost and difficulty of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 XRD spectra of the MAX phase material and the two-dimensional MXene material in Example 1 of the present invention (a); SEM photos of the MAX phase material (b) and the etched product (c, d);

[0024] Figure 2 These are SEM photos of samples obtained by stirring when the mass concentration of the positive ion pair reagent in Example 1 of the present invention is 1 wt.% (a), 5 wt.% (b), 10 wt.% (c), and 20 wt.% (d);

[0025] Figure 3 SEM photograph of the sample obtained in Example 1 of the present invention with a mass concentration of 20 wt.% of the positive ion pair reagent but without stirring;

[0026] Figure 4 TEM photo of the MXene nanoscroll obtained in Example 1 of the present invention (a), and the tube diameter distribution statistics (b);

[0027] Figure 5 TEM photos (a and b) and HRTEM photos (c and d) of MXene nanoscrolls at different magnifications in Example 1 of the present invention;

[0028] Figure 6 Element distribution diagram of MXene nanoscroll in Example 1 of the present invention;

[0029] Figure 7 XRD spectra of the MAX phase material and the two-dimensional MXene material in Example 2 of the present invention (a); SEM photos of the MAX phase material (b) and the two-dimensional MXene material (c);

[0030] Figure 8 TEM photo of the MXene nanoscroll obtained in Example 2 of the present invention (a), and the tube diameter distribution statistics (b);

[0031] Fig. 9 TEM photo (a) of the MXene nanoscroll in Example 2 of the present invention, HRTEM photos at different magnifications (b and c), and element distribution photos (e-j);

[0032] Fig.10 XRD spectra of the MAX phase material and the two-dimensional MXene material in Example 3 of the present invention (a); SEM photos of the MAX phase material (b) and the two-dimensional MXene material (c);

[0033] Fig.11 These are SEM photos 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);

[0034] Fig.12 is V in Example 4 of the present invention 2 AlC and V 2 CT x XRD spectrum (a), V 2 SEM image of AlC (b), SEM (c), TEM (d) and HRTEM (e) images of MXene nanoscrolls;

[0035] Fig.13 1 is a graph showing the cycle performance test result of the graphite electrode at a current density of 0.5C in Example 11 of the present invention (a) and a capacity comparison graph after 60 cycles (b);

[0036] Fig.14 This is a comparison of the cycle performance of the graphite electrode with different conductive agents added in Example 11 of the present invention. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is described below by specific embodiments. 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 combination step, 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 are not used to limit the scope of the present invention. Unless otherwise specified, the numbering of each method step is only for the purpose of identifying each method step, and does not limit the order of arrangement of each method or limit the scope of implementation of the present invention. The change or adjustment of the relative relationship thereof can also be regarded as the scope of implementation of the present invention without substantial changes in the technical content.

[0038] The sources of the raw materials and instruments used in the examples are not particularly limited and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0039] Example 1

[0040] This embodiment provides a MXene nanoscroll, whose chemical formula is V 2 B 0.28 C 0.57 N 0.15 T x The preparation method steps are as follows:

[0041] 1) Preparation of two-dimensional MXene materials from MAX phase materials

[0042] MAX Phase Material V 2 AB 0.28 C 0.57 N 0.15 Etching was performed at 90°C for 48h using an etchant to obtain a mixed solution containing an etchant (5 mg / ml); wherein the etchant was a mixed solution of concentrated hydrochloric acid (30 wt.%) and NaF, wherein the molar ratio of NaF to HCl was 1:1, and the obtained etchant was a two-dimensional MXene material, marked as: V 2 (B x C y N 1-x-y )T x ;

[0043] After the mixed solution containing the etched product is centrifuged and washed, the obtained etched product is characterized. Figure 1 a shows the XRD comparison of MAX phase material and etched product. It can be seen that the (002) diffraction peak of the etched product shifts to a low 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 the sheets increases. It can be seen from the SEM photos that the MAX phase material presents a typical layered block morphology ( Figure 1 b); while the etched product presents an accordion-like morphology of stacked flakes ( Figure 1 c and d), the interlayer spacing increases significantly, which is consistent with the previous XRD spectrum results. Figure 1 It can also be seen in c that the diameter of the etched material is about 1 μm to 10 μm, and most of the diameters are around 5 μm.

[0044] 2) Preparation of MXene nanoscrolls from two-dimensional MXene materials

[0045] The etched product obtained in step 1 was added to a 1 wt.% to 20 wt.% tetrabutylammonium hydroxide (TBAOH) aqueous solution, and after magnetic stirring (1500 r / min) for 5 min, ultrasonic (1000 W) for 30 min, and centrifuged for multiple cleanings to obtain a purified sample.

[0046] Figure 2 a~d show the SEM images of samples with 1wt.%, 5wt.%, 10wt.% and 20wt.% TBAOH addition, respectively. It can be seen that when 1wt.% TBAOH is added, the edge of the two-dimensional MXene material appears curled ( Figure 2 a), increasing the TBAOH concentration to 5wt.%, the edge curling of the two-dimensional MXene material is more obvious ( Figure 2 b) Continue to increase the TBAOH concentration to 10wt.%, and most of the two-dimensional MXene materials in the sample are in the state of nanoscrolls ( Figure 2 c), when the TBAOH concentration increases to 20wt.%, the two-dimensional MXene material in the sample is completely transformed into MXene nanoscrolls ( Figure 2 d). Figure 2 a~d clearly show the process of two-dimensional MXene material curling up to gradually form MXene nanoscrolls, and the edge curling of the same piece of two-dimensional MXene material forms a one-dimensional hollow nanoscroll structure. Figure 3 The SEM image of the sample with 20 wt.% TBAOH added but without stirring and ultrasonication is given. It can be seen that the sample has a thin and soft morphology, but no curling phenomenon occurs, indicating that external force is crucial to the formation of MXene nanoscrolls.

[0047] It can also be seen from the above examples that adding an appropriate amount of positive ion pair reagent to the liquid phase has a significant effect on accelerating the formation of MXene nanotubes. For example, when 20 wt.% of TBAOH is added, only 5 minutes of stirring and 10 minutes of ultrasound can obtain fully curled MXene nanorolls. In contrast, when only 1 wt.% of TBAOH is added, curling can be produced under the same conditions, but the nanoroll structure cannot be formed, and the stirring time needs to be extended. This can be explained by the fact that a higher concentration of positive ion pair reagent will graft more alkyl chains on the surface of the two-dimensional MXene material. Under the same external force, the external force generated is greater, and it is easier to quickly form a one-dimensional hollow roll structure. In the optimized experiment, the addition amount of the positive ion pair reagent can be between 1 wt.% and 50 wt.%, and the optimal addition amount of the positive ion pair reagent can be obtained through a limited number of experimental adjustments based on different types of MXene materials and the negative charge on the surface of the MXene material.

[0048] Stirring the liquid phase to produce a co-directional flow can provide a continuous and uniform external force for curling, which is important for obtaining a large amount of uniform MXene nanoscrolls. From the characterization results, it can be seen that the two-dimensional MXene material is almost completely transformed into MXene nanoscrolls, such as SEM (such as Figure 2 d) and TEM (such as Figure 6 a) As shown in the photo, that is, the present invention can prepare uniform and monodispersed MXene nanoscrolls in large quantities, which is of great significance for subsequent applications.

[0049] In other embodiments, the positive ion pair reagent can also be selected from one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrapentylammonium hydroxide. The difference between these reagents and TBAOH in this embodiment is the length of the alkyl chain, and it is reasonably predicted that they can also produce the same technical effect.

[0050] The obtained MXene nanoscrolls were subjected to transmission electron microscopy (TEM) test, as shown in Figure 4 As shown in a, it can be seen that the MXene nanoscroll has a significant one-dimensional morphology. The length of the MXene nanoscroll is between 0.5 μm and 5 μm, corresponding to the sheet diameter of the two-dimensional MXene material before winding, and each MXene nanoscroll is independently dispersed (monodispersed). Figure 4 b A statistical analysis was conducted on the diameters of MXene nanoscrolls, and it can be seen that the diameters of the nanotubes range from 20nm to 80nm, among which the content of MXene nanotubes with a diameter of 40nm is the highest, accounting for more than 40%.

[0051] Figure 5 a and b show TEM photos of MXene nanoscrolls at different magnifications. It can be clearly seen that the MXene nanoscrolls have a hollow scroll structure formed by curling a single piece of two-dimensional MXene material, a straight one-dimensional morphology, an open end, and a smooth tube wall. Figure 5 From the high-resolution electron microscopy (HRTEM) images of c and d, it can be seen that the wall of the MXene nanoscroll is composed of only 2 to 3 layers of MXene, with an interlayer spacing of 1.08 nm, that is, the thickness of the wall is only 3 nm to 4 nm, and the wall is ultra-thin, indicating that the MXene nanoscroll of the present invention is formed by curling a single layer of two-dimensional MXene material. Figure 5 d It can also be seen that the tube wall of the MXene nanoscroll shows the typical hexagonal lattice of MXene, indicating that the MXene nanoscroll has a crystalline structure.

[0052] Figure 6The element distribution of MXene nanoscrolls shown by TEM test is given. It can be seen that MXene nanoscrolls contain V, B, C, N, O, and F elements, and each element is evenly distributed. Among them, O and F elements are functional group elements on the surface of MXene nanoscrolls, which are consistent with their chemical formula V. 2 (B x C y N 1-x-y )T x match.

[0053] 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. 2 AB 0.28 C 0.57 N 0.15 It is prepared by a high-temperature sintering method, the steps comprising: sintering the single substance or compound of each element by high-temperature according to the stoichiometric ratio of the elements in the chemical formula of the MAX phase material. In the present embodiment, more specifically, vanadium powder (V), aluminum powder (Al), boron powder (B), carbon powder (C), and carbonized nitrogen (CN) are mixed and ball-milled in a molar ratio of 2:1:0.85:0.42:0.15, placed in a high-temperature sintering furnace, sintered at a high temperature of 1500°C for 24 hours in an argon atmosphere, and then cooled to room temperature.

[0054] 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, Li+ nitric acid; or other etching methods, such as the accordion-shaped MXene material obtained by vapor phase etching.

[0055] Example 2

[0056] This embodiment provides another MXene nanoscroll, whose chemical formula is: V 2 C 0.5 N 0.5 T x , the preparation method comprises:

[0057] 1) Preparation of two-dimensional MXene materials from MAX phase materials

[0058] MAX Phase Material V 2 AlC 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, is used for etching at 40°C for 48 hours. The etched product is a two-dimensional MXene material, which is marked as: V 2 (C x N1-x )T x .

[0059] 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 From the SEM photos of b and c, we can see that the MAX phase material presents a typical layered bulk morphology; after etching, the etched material presents an accordion-like morphology of stacked flakes, and the interlayer spacing is significantly increased, which is consistent with the previous XRD spectrum results. The flake diameter is about 5μm to 15μm.

[0060] 2) MXene nanoscrolls are obtained by curling two-dimensional MXene materials

[0061] 1 g of the above-mentioned etched product was added into a 30 wt.% TBAOH aqueous solution (50 ml), and after magnetic stirring for 10 min, the mixture was centrifuged and washed several times to obtain a purified sample.

[0062] The TEM test results of the samples are as follows: Figure 8 As shown in a, it can be seen that the sample also exhibits a significant one-dimensional morphology, and the length of the MXene nanoscroll is above 5 μm, which corresponds to the sheet diameter of the two-dimensional MXene material before winding, indicating that the MXene nanoscroll of the present invention is obtained by winding a two-dimensional MXene sheet; Figure 8 b A statistical analysis of the tube diameters of MXene nanoscrolls showed that the diameters of hollow scrolls ranged from 20nm to 140nm, among which MXene nanotubes with a diameter of 60nm had the highest content, accounting for more than 30%.

[0063] Fig. 9 The TEM photo of a shows that the port of the MXene nanoscroll is open. Fig. 9 b and c are HRTEM photos, showing the hollow roll structure of MXene nanoscrolls, with the tube wall consisting of approximately 3 to 6 MXene layers. Fig. 9 Figures e to j show the element distribution of MXene nanoscrolls. It can be seen that MXene nanoscrolls contain V, C, N, O, and F elements, and each element is evenly distributed. O and F are functional group elements on the surface of MXene nanoscrolls, which are consistent with their chemical formula V. 2 (C x N 1-x )T x match.

[0064] The MAX phase material in this embodiment is prepared by a high temperature sintering method, the steps comprising: sintering the single substance or compound of each element at a high temperature according to the element stoichiometric ratio in the chemical formula of the MAX phase material. In this embodiment, V 2 AlC 0.5 N 0.5 The 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, placing the mixture in a high-temperature sintering furnace, sintering at a high temperature of 1500° C. for 24 hours under an argon atmosphere, and cooling the mixture to room temperature.

[0065] Example 3

[0066] This embodiment provides a MXene nanoscroll, whose chemical formula is Ti 3 CNT x , the preparation method comprises the following steps:

[0067] 1) Preparation of two-dimensional MXene materials from MAX phase materials

[0068] The MAX phase material Ti 3 AlCN was etched with a mixture of concentrated hydrochloric acid (30 wt.%) and LiF at 40 °C for 48 h, where the molar ratio of LiF to HCl was 1:1, to obtain a two-dimensional MXene material, labeled Ti 3 CNT x .

[0069] pass Fig.11 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. Fig.11 From the SEM images of b and c, we can see that the MAX phase material presents a typical layered bulk morphology; the etched material presents an accordion-like morphology of stacked flakes, and the interlayer spacing is significantly increased. The flake diameter is between 3μm and 5μm.

[0070] 2) MXene nanoscrolls are obtained by curling two-dimensional MXene materials

[0071] The above-mentioned etched product was added into a TBAOH aqueous solution with a mass concentration of 10 wt.%, and after magnetic stirring for 30 minutes, it was centrifuged and washed several times to obtain a purified sample. Fig.11a~c show the SEM photos of the samples stirred for 1min, 10min, and 30min, respectively. It can be seen that the two-dimensional MXene material gradually curls up and finally obtains MXene nanoscrolls, where the diameter of the MXene nanoscrolls is about 200nm~300nm. It can be seen that the time of external force also has an effect on the formation of MXene nanoscrolls. At a lower concentration of positive ion pair reagents, extending the stirring time can also obtain MXene nanoscrolls.

[0072] Example 4

[0073] This embodiment provides another MXene nanoscroll used as a conductive component in a conductive paste, and its chemical formula is: V 2 CT x ; The preparation method comprises:

[0074] 1) MAX phase material V 2 AlC was etched with concentrated hydrochloric acid-NaF etchant at 90°C for 48h to obtain a two-dimensional MXene material-V 2 CT x ;

[0075] 2) adding the above two-dimensional MXene material to a 20 wt.% intercalation agent TBAOH solution, stirring magnetically for 5 minutes, centrifuging and purifying for multiple times, and then drying to obtain a MXene nanoscroll;

[0076] Fig.12 a gives V 2 AlC and V 2 CT x XRD spectrum of Fig.12 b gives V 2 SEM image of AlC, showing bulk material; Fig.12 c and d show the MXene nanoscrolls (V 2 CT x ) from SEM and TEM images, it can be seen that the MXene nanoscrolls present a monodispersed one-dimensional hollow nanoscroll morphology, with a tube diameter ranging from 40nm to 70nm and a length ranging from 2 to 5μm; Fig.12 e shows the HRTEM photo, from which it can be seen that the wall thickness of the MXene nanoscroll is between 2nm and 3nm, which is an ultra-thin wall.

[0077] Using a similar method, the applicant also prepared other types of MXene nanoscrolls with the same structural characteristics, including: Ti 2 CT x 、Ti 3 C 2 T x , Nb2 CT x 、TiNbCT x 、Cr 2 CT x 、Ti 3 CNT x 、 Ti 2 CT x 、Ti 2 C 0.5 N 0.5 T x 、Ti 0.5 V 0.5 C 0.5 N 0.5 T x 、V 2 CT x 、V 2 C 0.75 N 0.25 T x 、V 2 B 0.28 C 0.57 N 0.15 T x 、 (V 0.8 Cr 0.2 ) 2 B 0.33 C 0.67 T x 、(V 0.8 Cr 0.2 ) 2 CT x 、(V 0.8 Fe 0.2 ) 2 B 0.33 C 0.67 T x 、 (V 0.8 Mn 0.2 ) 2 B 0.33 C 0.67 T x 、(V 0.8 Fe 0.2 ) 2 B 0.28 C 0.57 N 0.15 T x 、(V 0.8 Mn 0.2 ) 2 B 0.28 C 0.57 N 0.15 T xIt 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.

[0078] Since the MXene nanoscroll of the present invention is formed by curling up a two-dimensional MXene material, the length of the MXene nanoscroll in one dimension is related to the sheet diameter of the two-dimensional MXene material. For the two-dimensional MXene material, the sheet diameter can be distributed between 0.1 μm and 100 μm. Therefore, we can reasonably predict that the length of the MXene nanoscroll can also be within this range.

[0079] The above examples 1 to 4 give in detail the preparation method, morphology and structural characteristics of the MXene nanoscroll of the present invention. In order to illustrate the conductive properties of the MXene nanoscroll of the present invention as a conductive agent, the etched material obtained in the above examples is centrifuged and washed, dispersed in a solvent for ultrasonic dispersion, and then freeze-dried to obtain a powder of a 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 is centrifuged and concentrated, and then freeze-dried to obtain a MXene nanoscroll powder. The conductivity of the two powders is tested by the four-probe method. The test method is: add 50 mg of powder sample to the sample slot of the four-probe powder resistance meter, flatten it, and then turn on the four-probe powder resistance meter, rotate the handle, move the upper probe of the resistance meter downward, and then pressurize it to 15 MPa, wait until the powder resistance meter reading is stable, read the resistivity reading, and then obtain the conductivity according to the conversion relationship of conductivity = 1 / resistivity. The results are shown in the following table:

[0080]

[0081] 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 a sheet overlap. 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 100S cm -1, which is significantly lower than the MXene nanoscroll of the present invention, which can be explained by the fact that the conductivity of MXene materials is better than that of carbon nanotube materials, and the monodisperse structure can reduce the contact resistance and the linear one-dimensional structure has better directional conduction of electrons.

[0082] Example 5

[0083] This embodiment provides an aqueous conductive slurry, wherein the MXene nanoscroll of the present invention is mixed with an aqueous solvent. Since the MXene nanoscroll of the present invention is only a change in the microscopic morphology of the MXene material, some properties of the MXene material, such as hydrophilicity, are still maintained. The MXene nanoscroll can be fully dispersed in the aqueous solvent to obtain an aqueous MXene nanoscroll conductive slurry. The aqueous solvent can be pure water; or it can be a mixture of water and alcohols, aldehydes, ketones, and ether compounds.

[0084] In some preferred embodiments, a certain amount of MXene nanoscroll is mixed with deionized water to obtain a MXene nanoscroll conductive slurry with a concentration between 0.01 wt.% and 90 wt.%, preferably, between 5 wt.% and 50 wt.%; more preferably, between 20 wt.% and 30 wt.%.

[0085] The conductive slurry of the MXene nanoscroll of the present invention has the characteristic of monodispersion. When the conductive component is only the MXene nanoscroll, no additional dispersant needs to be added. It can be dispersed by stirring or ultrasound. It has the characteristics of no agglomeration and easy dispersion. However, the conductive slurry of the present invention does not exclude the addition of other types of conductive agents. A small amount of dispersant or other functional components can also be added according to application needs.

[0086] Example 6

[0087] The present embodiment provides a conductive paste, in which the conductive agent includes the MXene nanoscroll of the present invention and a two-dimensional material. The two-dimensional material can be graphene or a two-dimensional MXene material. The MXene nanoscroll of the present invention is a typical one-dimensional material. When a two-dimensional material is added thereto to obtain a composite conductive paste, the beneficial effect is that a "surface-line-point" conductive network can be formed. Compared with the conductive paste of a single component conductive agent, under the condition of the same mass content of the conductive agent, the conductive paste of the composite component conductive agent has better conductive properties, thereby improving the conductivity of the material; under the condition of the same conductive properties, the mass content of the composite component conductive agent in the conductive paste is lower, which can save more costs.

[0088] In some specific embodiments, the conductive agent MXene nanoscroll and the 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 slurry.

[0089] In a specific preferred embodiment, the mass fraction of the conductive agent is between 0.1wt.% and 20wt.%;

[0090] In a specific preferred embodiment, the mass ratio of MXene nanoscrolls 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), more preferably, between 1:(0.8-1.5).

[0091] In other embodiments, the conductive graphene mentioned above may also be replaced by a two-dimensional MXene material; the ethylene glycol mentioned above may also be replaced by other alcohols, such as ethanol, propanol, isopropanol, butanol, etc.

[0092] Example 7

[0093] The present embodiment provides a composite conductive paste, specifically, a silver-aluminum paste containing MXene nanoscrolls, wherein the conductive components include metallic silver powder, aluminum powder and MXene nanoscrolls.

[0094] In one embodiment, the composite conductive paste contains, by weight, 30 to 80 parts of metal powder (including silver powder or aluminum powder), 1 to 20 parts of MXene nanoscrolls, 10 to 40 parts of organic carriers, 5 to 10 parts of dispersants and 3 to 10 parts of surfactants, and 2 to 10 parts of defoaming agents; wherein the mass ratio of silver powder to aluminum powder is between 2:8 and 8:2.

[0095] In some embodiments, the particle size of the silver powder particles is selected to be 1 to 10 μm, and the particle size of the aluminum powder particles is selected to be 3 to 10 μm; the organic carrier is obtained by mixing a resin and an organic solvent in a mass ratio of 10:90 to 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 a phosphate triester, 1,4-dihydroxysulfonic acid amine, or silicone oil; the defoamer is sodium dodecyl sulfonate, 2-methyl-4-ethylimidazole, or vinyl diphenylmethane; the surfactant is polyvinyl pyrrolidone, lactic acid monoglyceride, or ethylenediamine carboxylic acid triglyceride.

[0096] 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 10g of flaky silver powder, 30g of aluminum powder, 10g of MXene nanoscrolls, and 10g of organic carrier, and preliminarily mixing them in a blender, and then adding 5g of 1,4-dihydroxysulfonic acid amine, 5g of 2-methyl-4-ethylimidazole, and 5g of ethylenediamine carboxylic acid triglyceride into the blender in turn and mixing for 60 minutes to obtain a composite conductive slurry.

[0097] The steps of the implementation method include: mixing a resin with an organic solvent to obtain an organic carrier, adding a mixture of metal powder and MXene nanoscrolls into the organic carrier, and adding a dispersant, a defoaming agent, a surfactant, etc. to obtain the mixture after sufficient dispersion.

[0098] This embodiment provides an implementation method in which the conductive component is zero-dimensional metal powder and MXene nanoscrolls, wherein the one-dimensional MXene nanoscrolls can form a conductive network in the zero-dimensional metal particles to enhance the conductive performance. The metal powder in this embodiment can also be replaced by one or more other metals such as silver powder, aluminum powder, gold powder, copper powder, etc.

[0099] Example 8

[0100] This embodiment provides an organic solvent conductive paste and a preparation method thereof, comprising the steps of:

[0101] 1. Take a certain amount of dispersant polyvinylidene fluoride (PVDF) and add it to the organic solvent N-methylpyrrolidone (NMP), then stir at 600 rpm for 2h to 6h until the solution becomes a uniform transparent liquid;

[0102] 2. Take a certain amount of MXene nanoscrolls and add them into the above-mentioned stirred and dispersed liquid, and then stir and disperse them at a speed of 450 rpm to obtain an organic conductive slurry containing MXene nanoscrolls. Similarly, the same method is used to obtain a conductive slurry of carbon nanotubes.

[0103] In a preferred embodiment, the dispersant polyvinylidene fluoride (PVDF) is added in an amount of 1 wt.% to 5 wt.%, to promote the dispersion of the conductive component;

[0104] The addition amount of MXene nanoscrolls is not limited and can be between 0.001 wt.% and 99 wt.%; preferably, the addition amount is between 20 wt.% and 50 wt.%; more preferably, between 30 wt.% and 40 wt.% to form a better viscous slurry.

[0105] 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 carboxymethyl cellulose.

[0106] Example 9

[0107] This example adopts the method in Example 8 above, wherein the MXene nanoscroll is made of V 2 CT x Nanoscrolls, wherein 2 wt.% of dispersant PVDF is added in step 1; in step 2, a certain amount of MXene nanoscrolls is added to obtain conductive pastes with mass fractions of MXene nanoscrolls of 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90%, respectively; preferably, when the mass fraction is 30% to 50%, the conductive paste exhibits more suitable viscosity properties.

[0108] The same method was used to replace the MXene nanoscroll in this example with carbon nanotubes (purchased) to obtain a comparative carbon nanotube conductive paste.

[0109] Example 10

[0110] This embodiment provides an application of the conductive paste of the present invention in the field of batteries, and more specifically relates to an electrode sheet containing the conductive paste of the present invention. The method for manufacturing the electrode sheet includes:

[0111] The electrochemically active material, the conductive agent and the binder are mixed and pressed to obtain a dry electrode; taking the electrochemical material as silicon as an example, in a specific implementation, the steps include: more specifically, the silicon powder, MXene nanoscroll, and PVDF are mixed in a mass ratio of 7:1.5:1.5; the mixed powder is then loaded into a powder feeder, and the powder is sprayed on the copper foil using a dry sprayer. After the dry spraying is completed, the temperature is kept at 175°C (because the melting point of PVDF is 155-160°C) and hot pressed to obtain a composite material of silicon and MXene nanoscrolls.

[0112] Embodiment 11

[0113] In order to illustrate the technical effect of MXene nanoscrolls in electrode sheets compared with other types of conductive agents, and to further measure the effect of MXene nanoscroll materials on electrode performance with different loading amounts (thicknesses), this example provides a comparison of MXene nanoscrolls with MXene nanosheets, Ketjen black, graphene, carbon nanotubes (CNTs) and other conductive materials used in graphite electrodes. The MXene nanoscrolls are selected from the V in Example 4. 2 CTx MXene nanoscrolls.

[0114] The preparation method of the electrode and battery is as follows: Graphite, MXene nanoscrolls, and PVDF are mixed in a mass ratio of 90:5:5, and NMP is added to prepare a slurry. Then, a scraper of different heights is used to scrape the copper foil to obtain a loading of 4, 6, 8, and 10 mg / cm 2 The electrode with a loading amount was then vacuum dried to obtain the electrode. The electrode sheet was assembled into a full battery according to the negative electrode shell-negative electrode-diaphragm-electrolyte-lithium sheet-gasket-reed sheet-positive electrode shell, and a cycle test was performed at a current density of 0.5C. Using the same method, the MXene nanoscroll was replaced with Ketjen black, carbon nanotubes (CNT) and graphene to obtain a comparative electrode and a comparative battery.

[0115] like Fig.13 As shown, the loading capacity is 4 mg / cm 2 The cycling performance test of each electrode at a current density of 0.5C shows that the electrode containing MXene nanoscrolls has the best cycling capacity, which is still maintained at 312.2mAh / g at the 60th cycle, which is higher than the current conductive agent Ketjen black, CNTs, graphene and MXene nanosheets as additives. This shows that adding MXene nanoscrolls to the electrode can increase the capacity of the electrode material.

[0116] like Fig.14 As shown in a to c, the cycle performance diagrams of MXene nanoscrolls, Ketjen black, and carbon nanotubes (CNTs) as conductive agents at different loading amounts are given respectively. It can be seen that the MXene nanoscroll material has higher capacity and better cycle stability than Ketjen black and CNT at the same loading amount (thickness); in addition, as the loading amount (thickness) increases, the MXene nanoscroll improves the electrochemical performance of the electrode with a high loading amount due to its good conductivity and high uniformity, even when it reaches 10 mg / cm 2 The electrochemical performance is still excellent even with a loading of 100%. However, the battery capacity of Ketjen Black and CNT decreases significantly with the increase of loading. This shows that MXene nanoscrolls promote the application of thick electrodes.

[0117] The above is the technical effect verified by the button cell in the laboratory. For the electrode sheet, the loading amount of active substances in the electrode sheet can be further increased by optimizing the process, so that the loading amount is between 10mg / cm 2 The above increases the energy and volume density of the battery. There may be different optimal loadings for different electrochemical substances, which can be obtained through a limited number of optimizations.

[0118] The above provides 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, sensors, photovoltaic cells and other application scenarios that require conductivity.

[0119] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. Use of MXene nanorolls as a conductive agent, characterized in that, the MXene nanorolls are MXene materials with a one-dimensional hollow roll structure; the hollow roll structure is formed by curling single sheets and / or single layers of two-dimensional MXene materials; the preparation method of the MXene nanorolls includes: dispersing two-dimensional MXene materials or etched products with an accordion morphology obtained by etching MAX phase materials 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; the thickness of the tube wall of the MXene nanorolls ranges from 0.3 nm to 50 nm; the tube diameter of the MXene nanorolls ranges from 10 nm to 200 nm; the one-dimensional structure of the MXene nanorolls is linear.

2. Use of the MXene nanorolls as claimed in claim 1 as a conductive agent, characterized in that, the positive ion pair reagent is an alkyl quaternary ammonium compound; and / or, the liquid phase includes one or more of water, ethanol, and isopropanol; and / or, the external force action further includes stirring, or stirring and ultrasonic treatment; and / or, the mass content of the positive ion pair reagent in the liquid phase ranges from 1 wt.% to 30 wt.%.

3. Use of the MXene nanorolls as claimed in claim 2 as a conductive agent, characterized in that, the 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 stirring is a directional rotation.

4. Use of the MXene nanorolls as claimed in claim 1 as a conductive agent, characterized in that, The chemical formula of the MXene nanoroll is expressed as V 2 B 0.28 C 0.57 N 0.15 T x 、V 2 C 0.5 N 0.5 T x 、Ti 3 CNT x 、V 2 CT x 、Ti 2 CT x 、Ti 3 C 2 T x 、Nb 2 CT x 、TiNbCT x 、Cr 2 CT x 、Ti 3 CNT x 、Ti 2 C 0.5 N 0.5 T x 、Ti 0.5 V 0.5 C 0.5 N 0.5 T x 、V 2 C 0.75 N 0.25 T x 、(V 0.8 Cr 0.2 ) 2 B 0.33 C 0.67 T x 、(V 0.8 Cr 0.2 ) 2 CT x 、(V 0.8 Fe 0.2 ) 2 B 0.33 C 0.67 T x 、(V 0.8 Mn 0.2 ) 2 B 0.33 C 0.67 T x 、(V 0.8 Fe 0.2 ) 2 B 0.28 C 0.57 N 0.15 T x and (V 0.8 Mn 0.2 ) 2 B 0.28 C 0.57 N 0.15 T x one of them.

5. Use of the MXene nanorolls as claimed in claims 1 to 4 as a conductive agent, characterized in that, the two ends of the MXene nanorolls are open; and / or, the length of the MXene nanorolls ranges from 0.1 μm to 100 μm.

6. A conductive agent, characterized in that, the conductive agent includes: MXene nanorolls, the MXene nanorolls are MXene materials with a one-dimensional hollow roll structure; the hollow roll structure is formed by curling single sheets and / or single layers of two-dimensional MXene materials; the preparation method of the MXene nanorolls includes: dispersing two-dimensional MXene materials or etched products with an accordion morphology obtained by etching MAX phase materials 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; the thickness of the tube wall of the MXene nanorolls ranges from 0.3 nm to 50 nm; the tube diameter of the MXene nanorolls ranges from 10 nm to 200 nm; the one-dimensional structure of the MXene nanorolls is linear.

7. The conductive agent as claimed in claim 6, characterized in that, the positive ion pair reagent is an alkyl quaternary ammonium compound; and / or, the liquid phase includes one or more of water, ethanol, and isopropanol; and / or, the external force action further includes stirring, or stirring and ultrasonic treatment; and / or, the mass content of the positive ion pair reagent in the liquid phase ranges from 1 wt.% to 30 wt.%.

8. The conductive agent according to claim 7, characterized in that the 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 stirring is a directional rotation.

9. The conductive agent according to claim 6, characterized in that The chemical formula of the MXene nanocylinder is expressed 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.

10. The conductive agent according to claim 9, characterized in that the transition metal element includes: 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.

11. The conductive agent according to claim 6, characterized in that The chemical formula of the MXene nanoroll is expressed as V 2 B 0.28 C 0.57 N 0.15 T x 、V 2 C 0.5 N 0.5 T x 、Ti 3 CNT x 、V 2 CT x 、Ti 2 CT x 、Ti 3 C 2 T x 、Nb 2 CT x 、TiNbCT x 、Cr 2 CT x 、Ti 3 CNT x 、Ti 2 C 0.5 N 0.5 T x 、Ti 0.5 V 0.5 C 0.5 N 0.5 T x 、V 2 C 0.75 N 0.25 T x 、(V 0.8 Cr 0.2 ) 2 B 0.33 C 0.67 T x 、(V 0.8 Cr 0.2 ) 2 CT x 、(V 0.8 Fe 0.2 ) 2 B 0.33 C 0.67 T x 、(V 0.8 Mn 0.2 ) 2 B 0.33 C 0.67 T x 、(V 0.8 Fe 0.2 ) 2 B 0.28 C 0.57 N 0.15 T x , (V 0.8 Mn 0.2 ) 2 B 0.28 C 0.57 N 0.15 T x One of the following.

12. The conductive agent according to claim 6, characterized in that both ends of the MXene nanoroll are open.

13. The conductive agent according to any one of claims 6 to 12, characterized in that the length of the MXene nanoroll ranges from 0.1 μm to 100 μm.

14. The conductive agent according to any one of claims 6 to 12, characterized in that the conductive agent further comprises a two-dimensional material; and / or, the conductive agent further comprises a one-dimensional material; and / or, the conductive agent further comprises a zero-dimensional material.

15. The conductive agent according to claim 14, characterized in that the two-dimensional material is one or more of two-dimensional MXene material, graphene, graphite flakes; and / or, the one-dimensional material is carbon nanotubes and / or graphene rolls; and / or, the zero-dimensional material is carbon black and / or metal nanoparticles.

16. A conductive paste, characterized in that it comprises the conductive agent according to any one of claims 6 to 15 and a solvent.

17. The conductive paste according to claim 16, characterized in that the 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 nanoroll ranges from 0.001 wt.% to 90 wt.%; and / or, the conductive paste further comprises a dispersant.

18. The conductive paste according to claim 17, characterized in that the dispersant is selected from one or more of polyvinylidene fluoride, polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol or sodium carboxymethylcellulose.

19. A method for preparing the conductive paste according to any one of claims 16 to 18, characterized in that the steps include: 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 the MXene nanoroll; mixing the MXene nanoroll and the solvent in a certain proportion to obtain the conductive paste.

20. The preparation method according to claim 19, characterized in that the positive ion pair reagent is an alkyl quaternary ammonium compound; and / or, the liquid phase includes: one or more of water, ethanol, isopropanol; and / or, the external force action further includes stirring, or, stirring and ultrasonic treatment; And / or, the mass content of the positive ion pair reagent in the liquid phase is between 1 wt.% and 30 wt.%.

21. The preparation method according to claim 20, characterized in that the 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 stirring is a directional rotation.

22. The application of a conductive agent according to any one of claims 6 to 15, or a conductive paste according to any one of claims 16 to 18 in the fields of batteries, supercapacitors, printing and dyeing, conductive inks, and conductive inks.

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