Composite particle material, manufacturing method thereof, and electrode

Abstract

The present invention provides a novel composite particle material of a MXene nanosheet and a carbon microbody.　A composite particle material according to the present invention comprises 90 to 97 parts by mass of a sheet-shaped Ti3Ala(C(1.0-x)Nx)2 (0 ≤ x ≤ 0.25 and a is 0.01 or more) MXene and 3 to 10 parts by mass of a carbon microbody, while having an interdispersibility of 0.01 to 7.00 and a specific surface area of 75 m2 / g or more. The MXene nanosheet has an average thickness of 1.0 to 3.5 nm. In addition, the sphericity is 0.8 or more. A method for producing this composite particle material according to the present invention comprises a step for granulating an alcohol slurry, which contains aggregates formed of the MXene and the microbody, by means of a spray drying method.

Description

Technical Field

[0001] The present invention relates to a composite particle material of a novel MXene nanosheet and a microsome, a method for producing the same, and an electrode using the composite particle material.

Background Art

[0002] Conventionally, a particle material made of an MXene layered compound obtained by removing Al by acid treatment from MAX phase ceramics powder such as Ti3AlC2, which is a layered compound (in this specification, it may be appropriately referred to as "MXene particle material", "MXene nanosheet", "layered compound particle material", or simply "particle material").) is known (Patent Documents 1 to 6). Since Na ions and Li ions can be stored / desorbed in the void layer from which the Al layer has been removed in these MXene layered compounds, they can be used as a negative electrode active material for secondary batteries (storage batteries), an electrochemical reaction involving a Faraday current associated with a redox reaction at the electrode interface, and a pseudocapacitor (also referred to as a redox capacitor) that utilizes an electrochemical ion adsorption / desorption reaction at the electrode. Positive and / or negative electrode active material, and also because of its excellent conductivity, it is expected to be applied to electromagnetic wave shielding thin films, conductive thin films, etc.

[0003] MAX phase ceramics are layered compounds, and the general formula is M n+1 AX n and is represented as. In the formula, M is a transition metal (Ti, Sc, Cr, Zr, Nb, etc.), A is a Group A element, X is C, or [C (1.0-x) N x (0 < x ≤ 1.0)], and n is from 1 to 3.

[0004] Among them, when A is Al, since the bond between M - A is weaker than the bond between M - X, the Al layer is selectively removed by acid treatment. The present inventors have proposed a method for preparing MXene nanosheets by exfoliating them using a bead mill using micro-sized beads (Patent Documents 5 and 6).

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-63171 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-76739 [Patent Document 3] US Patent Application Publication No. 2017 / 0294546 [Patent Document 4] US Patent Application Publication No. 2017 / 0088429 [Patent Document 5] Patent No. 6564553 [Patent Document 6] Patent No. 6564552 Summary of the Invention [Problem to be solved by the invention]

[0006] When MXene nanosheets are used in secondary batteries (storage batteries) or pseudocapacitors, acetylene black is added as a conductive additive. To improve battery characteristics such as cycle life, rapid charge / discharge, and capacity, it is necessary to enhance ion diffusion and ensure smooth electron transfer to the current collector. Specifically, it is necessary to exfoliate the nanosheets to a single layer, increase the specific surface area of ​​the composite particle material composed of MXene nanosheets and conductive microparticles, and ensure that the conductive microparticles are uniformly distributed among the nanosheets. After extensive investigations, we succeeded in obtaining a composite particle material composed of MXene nanosheets and conductive microparticles that is effective as a negative electrode active material for secondary batteries (storage batteries) or as a positive and / or negative electrode active material for pseudocapacitors.

[0007] The composite particle material previously filed by the present applicant forms agglomerates of primary particles. Therefore, for industrial use, milling and classification are essential. While the commonly used milling method of applying physical stress to the agglomerates appears to produce a practically usable particle size, it was found that the agglomerate structure is locally destroyed. Furthermore, because the strength of the agglomerates is affected by the humidity environment, the resulting agglomerate structure varies depending on the season, making it impossible to obtain an industrially usable composite particle material. Using portions with a destroyed agglomerate structure in electrodes for secondary batteries or pseudocapacitors leads to significant degradation of their properties. Furthermore, milling using physical stress results in irregular particle shapes, making it difficult to form uniform films during electrode fabrication.

[0008] The present invention was completed in consideration of the above-mentioned situation, and aims to solve the problem of providing a composite particle material with high sphericity, which is a powder having a 3D porous aggregate structure with a high specific surface area, in which novel MXene nanosheets and microparticles are highly dispersed, a method for producing the same, and an electrode using the composite particle material. [Means for solving the problem]

[0009] The composite particulate material of the present invention, which solves the above-mentioned problems, comprises 3 to 10 parts by mass of conductive microparticles and Ti3Al a (C(1. 0-x )N x )2, (0≦x≦0.25, a is 0.01 or more) The MXene nanosheets contain 90 to 97 parts by mass as primary particles, and the MXene nanosheets have an average thickness of 1.0 to 3.5 nm, a mutual dispersion index (described below) of 0.01 to 7.00, a volume average diameter of 1.0 μm to 15.0 μm, and a sphericity of 0.80 or more.

[0010] (mutual dispersion degree) In Raman spectroscopy using a 532 nm laser, -1 Peak height A and 1332 cm -1 The ratio of the peak height B (B / A) to the peak height B is calculated for 100 samples, and the standard deviation calculated from the 100 B / A values ​​is taken as the mutual dispersion.

[0011] The method for producing a composite particulate material of the present invention, which solves the above-mentioned problems, comprises dissolving Ti3Al in a dispersion medium containing 50 mass % or more of water. a (C(1. 0-x )N x ) 2, (0≦x≦0.25, a is 0.01 or more) A peeling step of peeling MXene to form a peeled product; an acid treatment step in which the raw carbon particles are treated in a mixed acid solution of sulfuric acid and nitric acid at 70°C or higher for 10 minutes or more to obtain carbon particles; a mixing step of adding 0.8 to 1.0 mol / L of a water-soluble lithium salt and / or a water-soluble sodium salt to a mixture slurry of the exfoliated material and the carbon fine particles in a mass ratio of 90:10 to 97:3 and having a particle concentration of 11.5 to 17.0 mg / L, and stirring the mixture; To the mixture slurry, an alkaline aqueous solution of 0.4 to 0.7 mol / L is added to make the liquid alkaline and cause coagulation. a (C(1. 0-x )N x 2) (0≦x≦0.25, a is 0.01 or more) an aggregating step of obtaining a slurry of aggregates of MXene and the carbon microparticles; a granulation step in which the dispersion medium of the slurry is replaced with alcohol to prepare an alcohol slurry of the aggregate, and the alcohol slurry is granulated by a spray drying method under an inert atmosphere to obtain granules; It has. [Effects of the Invention]

[0012] The composite particulate material of the present invention has the above-mentioned structure, and when employed as an active material, it can provide an electrode that can exhibit high performance when used in a secondary battery (storage battery) or a pseudo-capacitor.

[0013] Furthermore, by using the manufacturing method for the composite particulate material of the present invention having the above-mentioned configuration, it is possible to produce a composite particulate material with an ideal 3D porous aggregation structure and high sphericity. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an AFM image of a peeled product obtained in the peeling step of Example 1. [Figure 2] 1 is an SEM photograph of a peeled product obtained in the peeling step of Example 1. [Figure 3] 1 shows XRD profiles of Ti3AlC2 and composite powder material in Example 1. [Figure 4] 1 is an SEM photograph of the composite powder material of Example 1. [Figure 5] 1 shows adsorption isotherms of composite powder materials of Examples 1 and 2 and Comparative Example 4. [Figure 6] 1 is an AFM image of a peeled product obtained in the peeling step of Example 2. [Figure 7] 1 is a SEM photograph of a peeled product obtained in the peeling step of Example 2. [Figure 8] 1 shows XRD profiles of Ti3AlC2 and composite powder material in Example 2. [Figure 9] 1 is a SEM photograph of the composite powder material of Example 2. [Figure 10] 1 is an SEM photograph of the composite powder material of Comparative Example 2. [Figure 11] FIG. 1 is a schematic diagram showing a unit cell of the MAX phase (Ti3AlC2). DETAILED DESCRIPTION OF THE INVENTION

[0015] The composite particle material, its manufacturing method, and electrode material of the present invention will be described in detail below based on embodiments. The composite particle material of this embodiment has excellent electrical properties, such as electrical conductivity, and has a large void layer formed within the crystal due to the removal of the Al layer. Therefore, it can be applied to active materials such as secondary batteries (Li-ion secondary batteries, Na-ion secondary batteries, etc.) and pseudocapacitors (negative electrode active materials in the case of secondary batteries, and positive and / or negative electrode active materials in the case of pseudocapacitors), electromagnetic wave shielding thin films, conductive thin film materials, etc. Note that the numerical values ​​described in this specification can be used as the upper or lower limits of a numerical range, in which case the range can be either inclusive or exclusive of the numerical value.

[0016] (Composite particle material) The composite particulate material of this embodiment is a composite of exfoliated MXene and particulate or tubular microparticles for application to electrode materials, etc. The exfoliated MXene particulate material is obtained by peeling off multilayer MXene, a powdered layered compound of several micrometers in size.

[0017] In this specification, when multiple upper and lower limit values ​​are set for a parameter, the upper and lower limit values ​​can be arbitrarily combined unless otherwise specified. The composite particulate material of this embodiment is a composite particulate material of MXene and microparticles.

[0018] The MXene content is 90-97% based on the sum of the masses of MXene and the microparticles, with the remaining 10-3% being microparticles. If the MXene content exceeds 97%, the effect of the microparticles as a barrier against drying shrinkage is reduced, and if it is below 90%, the function as an active material is impaired. Furthermore, if the MXene content exceeds 97%, electrons become less likely to move to the current collector, and if it is below 90%, the function as an active material is impaired. The lower limit of the MXene content is 93%, 92%, or 90%, and the upper limit is 97%, 96%, or 95%.

[0019] The composite particle material has a mutual dispersion of 0.01 to 7.00. The mutual dispersion is a value that defines the degree of dispersion between MXene and the microparticles. When carbon microparticles are used as the microparticles, the mutual dispersion was measured by Raman spectroscopy using a 532 nm laser at 400 cm for 100 randomly selected composite particle materials. -1 Peak height A and 1332 cm -1 The standard deviation calculated from the ratio (B / A) of the peak heights B of the Ti3Al composite particles to the peak heights B of the Ti3Al composite particles is the mutual dispersion. A small mutual dispersion is desirable; if it exceeds 7.00, electrons cannot be effectively transferred to the current collector. The mutual dispersion of the composite particle material can adopt lower limits of 0.01, 0.05, and 0.10, and upper limits of 7.00, 2.50, and 1.50. a (C(1. 0-x )N x )2, (0≦x≦0.25, a is 0.01 or more) When irradiated with a laser, MXene nanosheets are easily oxidized and anatase precipitates, so the analysis is performed at a laser intensity that does not precipitate anatase. -1 From 2000cm -1 Ti3Al a (C(1. 0-x )N x )2, (0≦x≦0.25, a is 0.01 or more) The vibration due to the functional group adsorbed on the titanium atom of the MXene nanosheet is 230-470 cm -1 (A peak) is the vibration of functional groups adsorbed on carbon atoms at 580 cm -1 On the other hand, for acetylene black, the carbon of the SP3 hybrid orbital appears at 1332 cm -1 (B peak) has SP2 hybrid carbon at 1500-1600 cm -1 appears in.

[0020] The composite particle material has a specific surface area of ​​75m 2 / g or more. The specific surface area is measured by the BET method using nitrogen after pre-treatment, such as heating in a vacuum at 110°C for 6 hours. The specific surface area of ​​the composite particle material is limited to a minimum of 75 m 2 / g, 80m 2 / g, 105m2 / g can be adopted, with an upper limit of 200m 2 / g, 185m 2 / g, 170m 2 / g can be used. The composite particle material preferably has an average pore diameter of 10.0 to 20.0 nm and an average pore volume of 0.30 to 0.70 mL / g. More preferably, the average pore diameter is 10.0 to 15.0 nm and the average pore volume is 0.40 to 0.60 mL / g. The average pore diameter and pore volume were measured by the BET method using nitrogen after pre-treatment, in which the material was heated in a vacuum at 110°C for 6 hours.

[0021] In our previous application, PCT / JP2021 / 018296, we disclosed a composite material obtained by preparing a slurry of agglomerated particle material in a liquid, centrifuging the resulting precipitate, air-drying it at room temperature, and then vacuum-drying it at 60°C to form agglomerates, which were then crushed under physical stress to produce a composite particle material (secondary particles). Air-drying takes more than 24 hours. The material shrinks during air-drying and vacuum-drying at 60°C. The shrinkage mechanism is that MXene nanosheets overlap and integrate, while carbon microparticles added as a shrinkage barrier migrate. This mechanism reduces the interdispersity and the specific surface area. Furthermore, the average pore diameter and average pore volume also decrease. Vacuum drying at 110°C after air-drying significantly shrinks the material, significantly reducing the specific surface area. On the other hand, spray-drying the composite agglomerated particle slurry in an alcohol solvent allows the droplets to dry instantly without shrinkage, resulting in a spherical composite particle material with a 3D porous agglomerated structure that has excellent interdispersity and a high specific surface area. The instantaneous spray-drying method for obtaining composite particle materials results in a larger specific surface area, as well as larger average pore diameter and average pore volume, compared to the commonly used method of obtaining composite particle materials as secondary particles by applying physical stress to aggregates. The term "3D porous aggregate structure" refers to a structure in which primary particles aggregate, forming gaps between them, resulting in a three-dimensional network of pores.

[0022] The composite particle material was prepared by placing a 0.3g sample on a 20cm 2When the MXene particles are uniformly spread on a plate and heated in a vacuum at 110°C for 5 hours, the mass change is preferably 1.0% or less. Under these heating conditions, the moisture contained between the MXene layers and attached to the outer surface volatilizes. By specifying the amount of volatilization, composite particle materials with low interlayer moisture content can be specified. Upper limits of mass change can be set to 0.8%, 0.6%, 0.4%, or 0.2%. The mass change within the specified range refers to the amount of moisture adsorbed from the air onto the outer surface of the composite particle material, not the water between the MXene layers. Residual moisture between the MXene layers can degrade the cycle characteristics of secondary batteries and pseudocapacitors. This residual water cannot be completely removed by vacuum heat treatment after cell fabrication for secondary batteries or pseudocapacitors. After spray drying, the composite particle material is preferably dried in a vacuum or inert atmosphere at 100–120°C.

[0023] The composite particle material has a bulk density of 0.1 to 0.5 g / cm 3 The lower limit is preferably 0.1 g / cm 3 , 0.15g / cm 3 can be adopted, with an upper limit of 0.45 g / cm 3 , 0.50g / cm 3 When producing a cell of a secondary battery or a pseudocapacitor, the method for producing an electrode film is not particularly limited, but it is preferable to produce the film so that the volume packing density of the composite particulate material to be contained is as high as possible.

[0024] For example, using general-purpose technology, composite particle materials with several different average secondary particle sizes and bulk densities can be mixed to form a film, such as continuous particle blending (meaning that the particle sizes of the composite particle materials blended change continuously, resulting in a relatively broad particle size distribution) in which composite particle materials with several different secondary particle sizes are blended to achieve the particle size distribution shown by Andreasen, which results in a close-packed structure, or two-stage particle blending in which composite particle materials with large and small secondary particle sizes are blended.

[0025] MXene is the formula for the MAX phase mentioned above, M n+1 AXn (M is a transition metal, A is a Group A element, X is C or (1.0-x) N x (0 < x ≤ 1.0), and n is from 1 to 3), Al is used for A, and the Al phase is removed by acid treatment. Among them, Ti3Al a (C(1. 0-x )N x )2, (0 ≤ x ≤ 0.25, a is 0.01 or more) is preferable. The lower limit of a can be 0.002. The upper limit of a is more preferably 0.05. When x exceeds 0.25, in the bead mill treatment using fine beads, particle formation rather than exfoliation progresses, and thin and large nanosheets cannot be obtained. In addition to these elements, O, OH, and halogen groups can be used as surface functional groups.

[0026] MXene is in the form of plates, leaves, flakes, sheets, etc., and is collectively defined as sheet-like. For MXene, the stacking direction of the layers of the layered compound is defined as the "thickness", and the innumerable directions orthogonal to the thickness are defined as the "sheet spreading direction". The thickness of MXene has an average thickness of 1.0 - 3.5 nm, preferably 1.5 - 3.0 nm. The average thickness is calculated as the average value of the values measured by AFM analysis using a Si wafer hydrophilized for 100 randomly selected particles. The size of the sheet can be measured by SEM by dropping the nanosheet on the hydrophilized Si wafer. The average size in the sheet spreading direction is preferably 0.1 - 2.0 μm, particularly more preferably 0.1 - 1.7 μm. When the maximum value in the direction orthogonal to the thickness is the "long side" and the minimum value is the "short side", for 100 randomly selected particles measured by SEM, the average value of [(long side + short side) / 2] is taken as the average size in the spreading direction. Ti3Al a (C(1. 0-x )N x )2, (0 ≤ x ≤ 0.25, a is 0.01 or more) In MXene, Ti3Al 0.02C2MXene has an average thickness of 1.74 nm and an average size of 0.78 μm, but when 5% of the carbon sites are replaced with nitrogen, the average thickness becomes 1.66 nm and the average size becomes 1.17 μm, and when 25% of the carbon sites are replaced with nitrogen, the average thickness becomes 1.81 nm and the average size becomes 1.61 μm. Replacing the carbon sites with nitrogen makes it easier to generate functional groups in water, reducing the interlayer bonding strength of MXene, allowing larger nanosheets to be obtained with monolayer-level thickness. Furthermore, lowering the firing (synthesis) temperature of MAX phase ceramics within a range that does not generate impurities reduces the interlayer bonding strength, making it possible to reduce the average size while maintaining monolayer-level thickness. For example, Ti3Al 0.02 In C2MXene, lowering the firing (synthesis) temperature of MAX phase ceramics from 1450°C to 1430°C reduces the average thickness to 2.06 nm and the average size to 0.25 μm. Further lowering it to 1410°C reduces the average thickness to 1.98 nm and the average size to 0.10 μm.

[0027] By producing composite particle materials from MXene nanosheets exfoliated to the monolayer level without shrinkage, electrode materials with excellent ion diffusion properties can be obtained. Furthermore, by using MXene nanosheets of appropriate size, composite particle materials with a high specific surface area can be obtained. By reducing the average size while maintaining monolayer-level thickness, composite particle materials with an even higher specific surface area can be obtained.

[0028] The interlayer distance of the (002) plane of MXene, as determined by XRD analysis, is preferably 1.400 to 1.700 nm. The interlayer distance of the void layer formed by the removal of the Al phase from the MAX phase by acid treatment is 0.770 to 0.470 nm, defined as the interlayer distance of the (002) plane of the MXene nanosheet powder measured in XRD minus the interlayer distance of the (002) plane of the corresponding MAX phase ceramic powder measured in XRD. The Li ion diameter is 0.18 nm, and the Na ion diameter is 0.28 nm, making it suitable for use as an anode active material in both Li-ion and Na-ion secondary batteries. The interlayer distance of the (002) plane of graphite powder is 0.33 nm, and repeated insertion and desorption of Na ions causes rapid degradation within a short period of time, making it unsuitable for use in Na-ion secondary batteries. This is why MXene nanosheets are particularly promising as an anode active material for Na-ion secondary batteries. If the gap is large, expansion and contraction due to the movement of ions is unlikely to occur, and it can be used without cycle deterioration even when rapidly charged and discharged. Here, the corresponding MAX phase ceramic powder is Ti3Al a (C(1. 0-x )N x )2, where a is 1. If the interlayer distance of the (002) plane of the MXene nanosheet is less than 1.400 nm, degradation occurs due to rapid charge and discharge when used as the negative electrode active material in a sodium-ion secondary battery. If it exceeds 1.700 nm, the capacity per gram decreases.

[0029] The size of the microscopic object is sufficient if it is on the order of nanometers, and being on the order of nanometers means that the longest part of the length of the microscopic object is 100 nm or less. The shape of the microscopic object may be any shape, such as amorphous, spherical, thin film, or fibrous.

[0030] The microparticles preferably have a primary particle diameter of 100 nm or less, preferably 30 to 50 nm, and more preferably 30 to 40 nm, and may be in the form of aggregates. The shape of the microparticles is not limited, and examples include spherical, sheet-like, tubular, hollow, and amorphous shapes.

[0031] In particular, the microparticles are electrically conductive. Examples of the microparticles include carbon microparticles made of a carbon material and metal microparticles made of a metal material. As the carbon microparticles, it is preferable to use highly conductive materials such as acetylene black, Ketjen black, carbon nanotubes, graphene, carbon fiber, graphite powder, and hard carbon powder. In addition to carbon microparticles and metal microparticles, inorganic microparticles made of other inorganic substances can also be used. As the inorganic microparticles, TiO2, Al2O3, SiO2, and BaTiO3 with a primary particle diameter of 100 nm or less can be used.

[0032] (Method of manufacturing composite particle material) The method for producing a composite particulate material of this embodiment includes an exfoliation step, a mixing step, an aggregation step, a granulation step, and other necessary steps, and is a production method that can be suitably employed for producing the composite particulate material of this embodiment described above. Peeling process The exfoliation process involves exfoliating layered multilayer MXene particles of several micrometers in size by colliding microbeads with the interlayers in a dispersion medium to obtain nanosheet-like exfoliated material slurry. Exfoliation occurs between each layer of the layered multilayer MXene. The exfoliated material is not particularly limited, but preferably has 1 to 3 layers.

[0033] The resulting exfoliated material is suspended in a dispersion medium to form an exfoliated material suspension. This exfoliated material suspension can be directly subjected to the mixing step, or the dispersion medium can be removed before the mixing step. The method for obtaining the particulate, layered multilayer MXene material is not particularly limited, but examples include the following methods.

[0034] MXene is obtained by acid-treating a raw material consisting of a Ti3-layered MAX phase ceramic powder to partially dissolve the Al layer. An example of a method for producing MXene is described below as a pretreatment process. The raw material used in the exfoliation process can have the same composition as the material that makes up the particle material described above. The composition does not change much during the exfoliation process.

[0035] This particulate material is treated with acid to dissolve some of the Al, turning it into layered multilayer MXene particles of several micrometers in size.This multilayer MXene is then mixed into a solvent whose main component is water to form a mixture, and then an exfoliation process is carried out in a bead mill that rotates at high speed using beads of 10 μm to 300 μm, resulting in an exfoliated suspension of nanosheet-like MXene exfoliated material.

[0036] The dispersion medium used in the peeling step is not particularly limited, but preferably contains 50% by mass or more of water, and may contain alcohols such as methanol, ethanol, and isopropanol, ketones such as methyl ethyl ketone and acetone, dimethylformamide, dimethyl sulfoxide, etc. It is more preferable that the dispersion medium contains 100% by mass of water.

[0037] The concentration of MXene in the mixture used in the peeling step is not particularly limited, but can be about 10.0 mg / mL to 20.0 mg / mL. The liquid property of the mixture is not particularly limited, but can be about pH 6.0 to 8.0.

[0038] The specific bead mill treatment in the exfoliation process will be described below. Exfoliation can be performed using a bead mill equipped with a mechanism for classifying the slurry mixture with minute beads by centrifugation. The exfoliated material obtained by bead mill treatment can be separated from the mixture before exfoliation by centrifugation at any time, and ultimately all of the MXene can be removed.

[0039] For example, the lower limit of the bead size can be 10 μm, 15 μm, 20 μm, 30 μm, or 40 μm, and the upper limit can be 300 μm, 200 μm, or 100 μm. If the bead size is 10 μm or more, classification of the beads and slurry is easy. If beads of 300 μm or less are used, peeling can be prioritized over reducing the size of the particulate material. These lower and upper limits can be used in any combination. If the bead size is within the appropriate range, the energy applied can be increased and peeling can be prioritized, so it is most preferable to use beads of 50 μm to 100 μm.

[0040] The material of the beads is not particularly limited, but ceramics such as zirconia, alumina, and silicon nitride can be used. Partially stabilized zirconia, which has high fracture toughness, is particularly preferred. On the other hand, with commonly used bead mills that use beads larger than 300 μm and separate the beads and slurry through minute gaps, reducing the size of the particulate material takes precedence over exfoliation. Similarly, with ball mills such as planetary ball mills that use beads or balls larger than 300 μm, reducing the size of the particulate material takes precedence over exfoliation. As a result, only a portion of the material is exfoliated, and only a portion of the exfoliated material is classified by centrifugation, which is not suitable for industrial use.

[0041] Furthermore, the exfoliation of MXene has traditionally been performed using ultrasonic irradiation. When ultrasonic waves are applied to a solvent, cavitation occurs, and the resulting collapse causes the powder particles to collide with each other, leading to the exfoliation of the layers that make up the layered compound. However, even when water, which is prone to cavitation, is used, only partial exfoliation occurs, making it unsuitable for industrial use. Even with methods using planetary ball mills, exfoliation is of course only partial; grinding takes precedence, and the temperature rises, causing significant surface oxidation, making it unsuitable for industrial use. For these reasons, the method used involves exfoliating only a portion of the powder using ultrasonic irradiation, followed by collection by classification using centrifugation.

[0042] The peripheral speed in the peeling process can be 6 m / sec to 12 m / sec. A peripheral speed of 8 m / sec to 10 m / sec is more preferable. A peripheral speed of 6 m / sec or higher improves peeling efficiency, while a speed of 12 m / sec or lower prevents excessive energy from being applied, suppressing the temperature rise of the resulting particulate material. This prevents the progression of oxidation on the surface of the resulting particulate material and reduces electrical resistance. The slurry feed rate can be 100 mL / min to 300 mL / min. The slurry particle concentration can be 10.0 mg / mL to 20.0 mg / mL.

[0043] If the concentration is below 10.0 mg / mL, the efficiency of producing MXene nanosheets will decrease, and if the concentration is above 20.0 mg / mL, peeling will not proceed sufficiently, so this range is preferable.

[0044] The slurry temperature is preferably in the range of 35° C. or less. If the temperature is 35° C. or less, surface oxidation can be suppressed, and the electrical resistance of the particulate material can be kept low.

[0045] A bead filling rate of 40% to 80% can be used. A rate of 40% or higher improves peeling efficiency, while a rate of 80% or lower facilitates classification of the beads and slurry. Whether or not a particulate material containing a large amount of the desired sheet-like particles has been produced can be determined by observation using SEM, TEM, etc. The thickness of the particulate material, in particular, can be determined by AFM analysis. The particulate material obtained in the peeling process can also be classified and used by methods such as centrifugation, if necessary. The optimal conditions for the peeling process vary depending on the size of the equipment, so these values ​​are not limited.

[0046] Preferably, the bead mill treatment results in 98% or more of the MXene being exfoliated by mass, more preferably 99% or more, and even more preferably 100%. If the exfoliation process is completed under conditions in which all of the MXene is exfoliated, the MXene can be used directly in the mixing process without removing the unexfoliated MXene. To remove MXene other than the exfoliated MXene, separation can be performed by centrifugation, filtration, or the like.

[0047] The zeta potential of the resulting exfoliated MXene was measured in water with a pH of 6 to 8. If no significant problems were encountered, the zeta potential was measured at pH 7. The zeta potential is preferably between -25.0 mV and -35.0 mV, and more preferably between -28.0 mV and -34.0 mV. The zeta potential of Ti3C2MXene nanosheets was -28.9 mV. Nanosheets with 3% of the carbon sites substituted with nitrogen were -29.3 mV, nanosheets with 5% of the carbon sites substituted with nitrogen were -31.5 mV, nanosheets with 10% of the carbon sites substituted with nitrogen were -32.1 mV, nanosheets with 15% of the carbon sites substituted with nitrogen were -32.4 mV, and nanosheets with 25% of the carbon sites substituted with nitrogen were -33.1 mV. The absolute value of the zeta potential can be interpreted as the amount of functional groups attached in water. The more functional groups attached in water, the higher the absolute value of the zeta potential. The formation of an appropriate amount of functional groups in water results in excellent peelability. The zeta potential of the MXene nanosheets and carbon microparticles is a negative zeta potential, as explained in the mixing process. The MXene nanosheets and carbon microparticles are immobilized with positively charged Li ions and / or Na ions in water by adding water-soluble Li salt and / or water-soluble Na salt. A moderate zeta potential is necessary; if the absolute value of the zeta potential is small, the resulting composite particle material will have low interdispersion and a low specific surface area. A high absolute value of the zeta potential makes it difficult for electrons to move, so it is preferable to select MXene nanosheets and carbon microparticles with an appropriate absolute value of the zeta potential.

[0048] The chemical composition of the MXene nanosheets was calculated using the atom % of Ti, Al, C, and N, assuming Ti to be 3, to determine the amount of Al, C, and N. For chemical analysis, the sample was weighed onto a platinum dish, and nitric acid, sulfuric acid, and hydrofluoric acid were added. The sample was then heated (to approximately 120°C) to dissolve it, and then heated at a higher temperature (300°C) to evaporate the nitric acid and hydrofluoric acid, producing a sample solution (sulfuric acid). The sample solution was then diluted appropriately and quantitatively analyzed by ICP.

[0049] Acid treatment process The acid treatment step is a step in which the raw carbon particles are treated with a mixed acid solution of sulfuric acid and nitric acid to obtain highly hydrophilic carbon particles. Examples of the raw carbon particles include acetylene black, Ketjen black, carbon nanotubes, graphene, carbon fiber, graphite powder, and hard carbon powder. Acetylene black, Ketjen black, and carbon nanotubes are preferred in terms of electrical conductivity, and acetylene black is more preferred in terms of both electrical conductivity, purity, and price.

[0050] In the acid treatment step, the carbon particles are suspended in mixed acid, and this suspension can be used as is in the mixing step, or the mixed acid can be removed as needed by repeated washing with water or the like, and the carbon particles can be used. Washing can be carried out until the pH of the washing solution reaches about 6, and can also be carried out until the pH reaches about 6.5, 7, or 8.

[0051] This treatment introduces functional groups such as COOH and CO groups onto the surface of the carbon particles, making them hydrophilic. After the treatment, the carbon particles become a carbon particle suspension dispersed in mixed acid. It does not matter whether this treatment is performed before or after the acid treatment process and the peeling process.

[0052] The treatment temperature is preferably 70°C or higher. It is particularly preferable to keep it below 95°C to prevent boiling. The treatment time is not particularly limited, but treatment for 10 minutes or more ensures hydrophilization. During treatment, stirring or ultrasonic irradiation can be performed. After treatment, the mixture may be directly subjected to the mixing step, or the acid may be neutralized or separated. If the pH is raised above a predetermined value by neutralizing or separating the acid, the carbon particles will aggregate, so neutralization should be performed to a degree that does not cause the pH to reach the predetermined value. An example of a method for separating the acid is a method in which the solid content is separated by a classification operation such as centrifugation.

[0053] The mixing ratio of sulfuric acid to nitric acid can be about 4:1 to 1:1 by volume, and preferably about 3:1 to 3:2. The concentration of the mixed acid can be about 42% to 96%, and preferably about 90.0% to 95.0%.

[0054] The zeta potential of the obtained hydrophilic carbon particles is preferably -20.0 mV to -25.0 mV in water with a pH of 6 to 8. The zeta potential is negative due to the adsorption of COOH and CO as functional groups. If the absolute value is less than -20.0 mV, the MXene nanosheets, which have a negative zeta potential as described in the mixing step, cannot be immobilized with positively charged Li ions and / or Na ions in water by adding water-soluble Li salt and / or water-soluble Na salt, resulting in a composite particle material with low interdispersity and a low specific surface area. It is preferable to select MXene nanosheets and carbon particles with an appropriate absolute value of zeta potential.

[0055] ·Mixing process The mixing step is a step of obtaining a mixture in which the exfoliated material and carbon microparticles are dispersed in a second dispersion medium containing 50% or more by mass of water at a mass ratio of 90:10 to 97:3 and a concentration of the exfoliated material of 11.5-17.0 mg / mL. It is more preferable that the second dispersion medium contains 100% by mass of water. By adding other substances to the mixture, the substances can also be incorporated into the composite particle material.

[0056] In particular, the coexistence of Li ions or Na ions allows the MXene and carbon particles constituting the exfoliated material to be immobilized. Specifically, it is preferable to immobilize the negatively charged functional groups adsorbed on the MXene in water and the negatively charged functional groups adsorbed on the carbon particles with Li ions and / or Na ions, which are positively charged in water. Examples of water-soluble lithium salts include lithium chloride and lithium carbonate, and examples of water-soluble sodium salts include sodium chloride and sodium carbonate. Adding a water-soluble salt of a strong alkali or strong acid and stirring for a long period of time can cause a reaction between the MXene nanosheets and the water-soluble salt, resulting in the precipitation of lithium titanate or sodium titanate locally on the MXene surface. Therefore, water-soluble salts that maintain neutrality after dissolution in water are preferred. It is preferable to add the water-soluble salt to the MXene aqueous slurry at a concentration of 0.8 mol / L to 1.0 mol / L. A concentration below 0.8 mol / L results in insufficient immobilization, while a concentration above 1.0 mol / L leaves a large amount of excess ions. The mixture contains the exfoliated material at a concentration of 11.5-17.0 mg / mL. The second dispersion medium may be the same as or different from the dispersion medium used in the peeling process or the solvent used in other processes. When the suspension of peeled material obtained in the peeling process is directly subjected to the mixing process, the second dispersion medium contains the dispersion medium used in the peeling process. The reason for limiting the MXene particle concentration in the composite slurry to 11.5-17.0 mg / mL is that if the concentration is below 11.5 or above 17.0, the specific surface area of ​​the composite particle material obtained in the aggregation process described below will be small.

[0057] For the acid-treated carbon particles, a predetermined amount of carbon particles is added to pure water and stirred for 12 hours or more using a shaker at a rotation speed of 100 to 300 rpm and an amplitude of 40 to 50 mm, more preferably at a rotation speed of 100 to 200 rpm and an amplitude of 45 to 50 mm. The resulting carbon particle aqueous slurry is then added to and mixed with the MXene aqueous slurry. The shaker conditions are preferably a rotation speed of 100 to 300 rpm and an amplitude of 40 to 50 mm, more preferably at a rotation speed of 100 to 200 rpm and an amplitude of 45 to 50 mm. More preferably, an aqueous slurry of acid-treated carbon particles and a water-soluble salt are simultaneously added to an aqueous MXene slurry, and the mixture is stirred for 4-6 hours using a shaker at a rotation speed of 100-300 rpm and an amplitude of 40-50 mm, thereby immobilizing the uniform arrangement of MXene nanosheets, Na and / or Li ions, and carbon particles in the liquid, resulting in an aqueous slurry of uniformly dispersed composite agglomerated particles. In both cases, a rotation speed of more than 300 rpm tends to destroy the nanosheets, while a speed of less than 100 rpm makes uniform mixing impossible. A speed of more than 50 mm tends to destroy the nanosheets, while a speed of less than 40 mm makes uniform mixing impossible.

[0058] ·Agglomeration process The aggregation step is a step in which an alkaline aqueous solution of 0.4 to 0.7 mol / L is added to the mixture slurry obtained in the mixing step to increase the pH of the liquid, thereby agglomerating the exfoliated material and carbon particles contained in the mixture to form aggregates dispersed in the liquid. The pH is preferably increased to about 12 to 14.

[0059] The alkaline aqueous solution is preferably lithium hydroxide and / or sodium hydroxide. The pH can be increased by adding an alkaline substance or by removing or diluting an acidic substance. The pH is preferably increased by adding the alkaline aqueous solution over a few seconds and stirring within one hour using a shaker at a rotation speed of 100 to 300 rpm. The amplitude of the shaker is preferably 40 to 50 mm. In either case, a rotation speed of 300 rpm or less prevents destruction of the nanosheets, while a rotation speed of 100 rpm or more facilitates uniform mixing.

[0060] An amplitude of 50 mm or less prevents nanosheet destruction, while 40 mm or more facilitates uniform mixing. It is more preferable to use a shaker with a rotation speed of 100 to 200 rpm and an amplitude of 45 to 50 mm for one hour or less. The alkaline aqueous solution is preferably added so that the total amount of water contained in the aqueous slurry of the composite agglomerated particle material is 0.4 mol / L to 0.7 mol / L. A concentration of 0.4 mol / L or more ensures sufficient agglomeration, while a concentration of 0.7 mol / L or less is preferable because it prevents excess ions from remaining. Although the exact reason is unclear, adding an amount within this range can produce a composite particle material with a high specific surface area. Furthermore, a highly hydrophobic organic solvent with a low dielectric constant can also be added.

[0061] ·Pelletization process The granulation step is a step in which the main component of the dispersion medium contained in the aggregates dispersed in the liquid obtained in the aggregation step is replaced with alcohol to form an alcohol slurry, and the alcohol slurry is granulated by a spray-drying method to form granules. These granules are used as they are or dried to form the composite particulate material of this embodiment. In this step, the droplets are instantly dried by the spray-drying method, thereby forming spherical granules having a porous structure.

[0062] The method for replacing the main component of the dispersion medium contained in the aggregate dispersed in the liquid with alcohol is not particularly limited. For example, the alcohol content can be increased by simply adding alcohol, or by repeatedly adding alcohol and then removing the dispersion medium. The dispersion medium can be removed by centrifuging the dispersion medium and separating it as a supernatant, or by evaporating the dispersion medium.

[0063] Here, alcohol being the main component means that the alcohol content is 50% or more based on the entire dispersion medium, and the lower limit of the alcohol content is preferably 90 vol%, 95 vol%, or 99 vol%.

[0064] Although there are no particular limitations on the alcohol that can be contained in the alcohol slurry, it is preferable to select an alcohol solvent that evaporates at low temperatures to further suppress surface oxidation of the MXene nanosheets. For example, it is preferable to use at least one of methanol, ethanol, and isopropanol as the alcohol used as the dispersion medium. In addition to alcohol, water, ketones such as MEK, or DMSO may also be contained. The lower limit of the alcohol content, based on the volume of the dispersion medium, can be 99%, 95%, or 90%.

[0065] The spray drying method is carried out in an inert atmosphere that has low reactivity with each of the materials that make up the composite particle material. The inert atmosphere can be an atmosphere filled with an inert gas such as nitrogen or argon, or a reduced pressure or vacuum atmosphere. The temperature of the inert atmosphere is a temperature at which the alcohol contained in the alcohol slurry can evaporate. For example, the lower limit of the temperature of the inert atmosphere can be 80°C, 90°C, or 100°C, and the upper limit can be 100°C, 110°C, or 120°C. The upper and lower limits can be combined arbitrarily.

[0066] The spray drying method involves spraying droplets of a slurry of the composite agglomerate material into a high-temperature atmosphere. Conventional methods for spraying can be used, such as a method using a rotating disk or a method using a nozzle such as a two-fluid nozzle. The method using a rotating disk is preferred because the agglomerated particles in the alcohol slurry are less likely to clog during spraying and because it is possible to produce spherical granules with any desired secondary particle size. Spherical granules with the required secondary particle size can be easily obtained by arbitrarily selecting the rotation speed of the rotating disk. Note that instead of or in addition to the spray drying method, a granulation step using a fluidized bed granulation method can be included.

[0067] The dispersion medium is instantly removed from the sprayed droplets composed of the composite agglomerated particle material and alcohol, forming a composite particle material without shrinkage, maintaining a high specific surface area and excellent mutual dispersion of the MXene nanosheets and carbon microparticles. The large particle size of the agglomerated particles in the alcohol slurry makes it prone to clogging during spraying or liquid delivery. Therefore, it is necessary to appropriately select the solids concentration, preferably 1.0 to 10.0 mass%. 1.0 to 5.0 mass% is even more preferable. Regarding secondary particle size, when using the rotating disk method, large secondary particle sizes can be obtained by lowering the rotation speed and increasing the spray temperature. On the other hand, small secondary particle sizes can be obtained by increasing the rotation speed. Furthermore, even smaller secondary particle sizes can be obtained by reducing the agglomerated particle size of the alcohol slurry of the composite agglomerated particle material and spray-drying it using a nozzle such as a two-fluid nozzle. By combining these methods, an average secondary particle size of 1.0 μm to 15.0 μm can be obtained. A range of 1.0 μm to 10.0 μm is more preferable. For spray drying using a nozzle such as a two-fluid nozzle, it is preferable to use an alcohol slurry in which large aggregates have been removed with a sieve to prevent nozzle clogging. In practice, an average secondary particle diameter of 1.0 μm or more is preferable because it prevents the composite particle material from scattering during processing. A value of 15.0 μm or less allows the composite particle material to be formed without using a high-particle-concentration alcohol slurry to enlarge droplets at low speed or without instantaneous alcohol removal at high temperatures. This is particularly preferable because high-temperature processing can be avoided, reducing the likelihood of problems such as surface oxidation of MXene. For use as a battery material, an average secondary particle diameter of 1.0 μm to 15.0 μm is preferable, with 1.0 μm to 11.0 μm being more preferable. A value of 1.0 μm or more facilitates handling, while a value of 15.0 μm or less suppresses the formation of unevenness in the resulting film. A value of around 11.0 μm (10.5 μm to 11.5 μm) is particularly preferable.

[0068] ·Drying process The granules obtained in the granulation step can be used as the composite particulate material of this embodiment as is, but can also be dried afterward to remove interlayer water from the MXene nanosheets. The drying step involves drying the granules at 100-120°C in a vacuum or inert atmosphere to produce the composite particulate material of this embodiment. Here, the vacuum or inert atmosphere is used to suppress oxidation of the MXene nanosheets, and any atmosphere that can suppress oxidation compared to air will suffice.

[0069] Suppressing the residual interlayer water in MXene nanosheets can suppress deterioration of characteristics when used as electrodes in secondary batteries or pseudocapacitors with increased cycle counts. The temperature in the drying process is determined by the temperature of the granules. The temperature of the granules can be controlled by controlling the ambient temperature, directly heating the granules with infrared rays, or by controlling the temperature of the container that holds the granules and controlling the temperature of the granules through heat transfer.

[0070] The drying process is performed at a temperature that does not denature the MXene nanosheets or that allows for tolerable denature, and that allows for the removal of moisture between the MXene nanosheet layers. The drying process effectively removes interlayer water. For example, it can easily reduce the moisture content to less than 10% by mass based on the total mass. The drying process time is not particularly limited, but it is preferable to perform the drying process until the moisture content is less than 10% based on the total mass, or until the mass change is 1.0% or less per hour. It is more preferable to maintain the moisture content at 8% or less, 6% or less, 4% or less, 2% or less, or 1% or less, and it is even more preferable to perform the drying process until the mass change is 0.5% or less per hour.

[0071] Other necessary processes Other necessary processes are not particularly limited, but include a pretreatment process. The pretreatment process is an example of a method for producing MXene. For example, a mixed raw material of TiC, TiN, Al, and Ti is subjected to CIP or uniaxial pressing at 1 ton / cm. 2 to 3 tonnes / cm 2The crushed pieces of the compacted powder, which have been pressure-treated in the range of 1400 to 1600°C, or without pressure treatment, are heat-treated in an inert atmosphere at temperatures between 1400°C and 1600°C to produce Ti3Al, a high-purity Ti3-layer MAX phase ceramic. a (C(1. 0-x )N x )2, (0≦x≦0.25, a is 1.0). Alternatively, the MAX phase ceramic powder can be contacted with an acidic substance at a controlled temperature of 20 to 30°C to remove a portion of the Al element contained in the MAX phase ceramic powder.

[0072] The raw materials used in the pretreatment process are Ti3Al for the Ti3 layer. a (C(1. 0-x )N x )2, (0≦x≦0.25, a is 1.0). Furthermore, the amount of Al removed is adjusted so that the amount of Al (corresponding to x) remaining in the MAX phase ceramic powder produced by acid treatment with an acidic substance is 0.01 or more. A lower limit of 0.02 can be used. It is more preferable to adjust the upper limit to 0.05. It is also possible to remove all of the Al, but in that case, it is preferable not to proceed with the acid treatment beyond the removal of the Al.

[0073] The amount of Al removed can be adjusted by changing the contact time with the acidic substance (such as an acidic aqueous solution) (the longer the contact time, the greater the amount removed), the concentration of the acidic substance (the higher the concentration, the greater the amount removed), the amount of acidic substance (the greater the absolute amount of acidic substance, the greater the amount that can be removed), and the contact temperature (the higher the temperature, the greater the amount removed).

[0074] A layered compound MAX phase ceramic powder (A element is Al) is subjected to acid treatment to remove part of the Al, resulting in a multi-layered layered compound several micrometers in size with a void layer that constitutes the particle material. The acid used to remove part of the Al layer is an acidic substance that combines hydrofluoric acid and hydrochloric acid. To achieve this combination of hydrofluoric acid and hydrochloric acid, it is preferable to mix a salt of hydrofluoric acid (such as KF or LiF) with hydrochloric acid to obtain a mixture of hydrofluoric acid and hydrochloric acid.

[0075] In particular, aqueous solutions of these acids are used as the acidic substance. The mixed concentration of hydrofluoric acid and hydrochloric acid formed when the fluoride salt is assumed to be completely dissociated is not particularly limited. The lower limit of the hydrofluoric acid concentration can be approximately 1.7 mol / L, 2.0 mol / L, or 2.3 mol / L, and the upper limit can be approximately 2.5 mol / L, 2.6 mol / L, or 2.7 mol / L. The lower limit of the hydrochloric acid concentration can be approximately 2.0 mol / L, 3.0 mol / L, or 4.0 mol / L, and the upper limit can be approximately 13.0 mol / L, 14.0 mol / L, or 15.0 mol / L.

[0076] The mixing ratio (molar ratio) of hydrofluoric acid and hydrochloric acid formed when the fluoride salt is assumed to be completely dissociated is not particularly limited, but the lower limit of hydrofluoric acid may be 1:13, 1:12, or 1:11, and the upper limit may be 1:5, 1:6, or 1:7. The concentrations and mixing ratios of hydrofluoric acid and hydrochloric acid shown here may be arbitrarily combined. The acid treatment temperature is preferably 20°C to 30°C, and more preferably 20°C to 25°C.

[0077] (electrode material) The electrode material of this embodiment is a material that can be suitably used in secondary batteries. In particular, since it is possible to insert and desorb Li ions and Na ions between the layers, it can be suitably used as an electrode active material. In addition, due to its conductivity, it can also be used as a conductive auxiliary agent. It is effective in lithium secondary batteries and sodium secondary batteries. Lithium ions and sodium ions are stored and desorbed in the void layer formed by removing the Al layer by acid treatment.

[0078] Here, a lithium secondary battery will be used as an example. The electrode includes an active material layer containing an active material made of the composite particle material of this embodiment and a current collector made of a thin metal plate or the like, on whose surface the active material layer is formed. A binder can be included to form the active material layer. Furthermore, the active material layer can contain active materials other than the composite particle material of this embodiment, conductive additives, and the like, as needed. Examples of binders that can be used include commonly used binders such as carboxymethyl cellulose, polyvinylidene fluoride, styrene-butadiene rubber, polyvinylpyrrolidone, and polyvinyl alcohol, as well as other binders. Examples of conductive additives that can be used include acetylene black, Ketjen black, carbon nanotubes, graphene, carbon fiber, graphite powder, and hard carbon powder. [Example]

[0079] The composite particle material and the method for producing the same of the present invention will be described in detail below with reference to examples.

[0080] Example 1 Pre-treatment process 12.3 g of TiC powder (TI-30-10-0020, Rare Metallic Co., Ltd.), 4.9 g of Ti powder (TIE07PB 3N, Kojundo Chemical Co., Ltd.), and 2.8 g of Al powder (ALE15PB 3NG, Kojundo Chemical Co., Ltd.) were mixed in isopropanol (IPA) using a ball mill for 12 hours, and the IPA was removed using an evaporator to obtain a uniformly mixed dry powder.

[0081] The uniformly mixed dried powder was placed in an alumina crucible and fired in a graphite resistance furnace in an Ar stream at 1450°C for 2 hours to obtain Ti3AlC2 as MAX phase ceramics. The obtained Ti3AlC2 was coarsely ground using a mortar and pestle, and then ball milled in IPA using 5mm zirconia balls for 24 hours. This was then ground in a planetary ball mill using 0.5mm zirconia balls (200 rpm, 15 minutes, three times) to obtain a suspension. The IPA was removed from the suspension using an evaporator, and Ti3AlC2 powder milled to approximately 3μm was obtained.

[0082] An acid solution of 18 g of LiF in 300 mL of concentrated HCl was prepared, and 10 g of Ti3AlC2 powder was added while cooling with ice. The solution was stirred with a magnetic stirrer for 24 hours in a controlled environment of 10 to 20°C, and the Al was etched and removed, resulting in Ti3Al 0.02 A particulate material consisting of C2MXene was obtained. After etching, the material was washed with water until the pH reached about 6, and finally the water was replaced with ethanol. This procedure resulted in a raw material suspension of the particulate material suspended in ethanol.

[0083] The particle concentration of the raw material suspension was measured, and Ti3Al 0.02 Water was added to adjust the particle concentration of C2MXene to 15.6 mg / mL.

[0084] Peeling process This raw material suspension was processed in a bead mill with ZrO2 beads of 50 μm diameter at a slurry feed rate of 150 mL / min and a ZrO2 bead filling rate of 80%, to produce Ti3Al 0.02 This process was repeated three times to produce exfoliated material consisting of C2MXene. 0.02 Almost all (99% or more by mass) of the particulate material consisting of C2MXene became exfoliated material, and an exfoliated material suspension containing the exfoliated material was obtained.

[0085] The resulting exfoliated suspension was dropped onto a piranha-treated Si substrate (immersed in a 3:1 volume mixture of H2SO4:H2O2) and subjected to AFM analysis. Figure 1 shows the AFM image. One hundred exfoliated nanosheets were randomly selected, and the average thickness measured by AFM was calculated and shown in Table 1. Figure 2 also shows the results of SEM observation. One hundred exfoliated nanosheets were randomly selected, and the vertical (maximum diameter in the direction perpendicular to the thickness) and horizontal (directions perpendicular to the vertical and thickness directions) dimensions were measured from the SEM images. The average value was defined as the size of the exfoliated nanosheets. The average size of the 100 exfoliated nanosheets is shown in Table 1. XRD analysis was performed on powder of Ti3AlC2, a MAX phase ceramic, and the resulting profile is shown in Figure 3. The zeta potential of the exfoliated nanosheets in water at pH 7.0 was measured to be -28.9 mV.

[0086] Acid treatment process To acid-treat acetylene black as carbon microparticles, 1.0 part by mass of acetylene black was added to 100 parts by mass of a mixed acid (a 3:1 volumetric mixture of sulfuric acid (98% by mass) and nitric acid (68% by mass)) and immersed at 85°C for 10 minutes. The mixture was then washed with water until the pH reached approximately 6.0, after which the water was replaced with IPA. The mixture was air-dried at room temperature to obtain hydrophilic acid-treated acetylene black powder. FTIR analysis detected COOH and CO groups as surface functional groups. The zeta potential at pH 7.0 in water was measured to be -22.5 mV. The acid-treated acetylene black was deagglomerated in a shaker at 140 rpm with an amplitude of 45 mm for 24 hours to prepare a hydrophilic acetylene black aqueous slurry. The hydrophilic acetylene black aqueous slurry was then dropped onto a hydrophilically treated Si wafer and observed using an SEM. One hundred primary particles were randomly observed, and the vertical and horizontal dimensions were measured. The average primary particle diameter is shown in Table 1.

[0087] Mixing and flocculation processes 5.3 g of lithium chloride powder and acetylene black powder treated with acid in the acid treatment step were added to 220 mL of the exfoliated material suspension with a particle concentration of 15.6 mg / mL obtained in the exfoliation step. 0.02After adding 0.172 g of acetylene black (5% by mass based on C2MXene), the mixture was uniformly stirred for 5 hours at 140 rpm and 45 mm amplitude on a shaker. As previously described, acetylene black was added as a slurry in 10 mL of water. After uniform stirring, an alkaline aqueous solution was added, which had been prepared by dissolving 3.5 g of lithium hydroxide in 30 mL of pure water and shaking for 1 hour at 140 rpm and 45 mm amplitude. The mixture was then stirred for 1 hour at 140 rpm and 45 mm amplitude on a shaker. The mixture was then washed with water once and substituted with ethanol three times. The mixture was then stirred in ethanol at 140 rpm for 6 hours to break down coarse aggregates, yielding an ethanol slurry of aggregates with a particle concentration of 5.0 mg / mL. The water washing and ethanol substitution were performed by adding water or ethanol, then centrifuging the aggregates at 1000–8000 G for 10 minutes, and removing the supernatant. The content of ethanol as alcohol in the obtained alcohol slurry was 99% based on the mass of the entire dispersion medium.

[0088] ·Pelletization process Granules were prepared by spray-drying an alcohol slurry of the composite agglomerated particle material using a spray dryer under the following operating conditions: disk rotation speed 20,000 rpm, nitrogen atmosphere, alcohol slurry temperature to the disk 80°C, alcohol slurry injection rate 1.4 kg / h.

[0089] ·Drying process The granules obtained in the granulation step were dried in a vacuum at 110°C for 6 hours to remove interlayer water, thereby obtaining the MXene / conductive carbon black composite particle material of this example.

[0090] ·evaluation An SEM photograph of the obtained composite powder (Figure 4) is shown. As is clear from the image, the obtained composite particle material has high sphericity, and when magnified, it is clear that the 3D porous aggregate structure of extremely thin MXene nanosheets in which acetylene black is uniformly dispersed is maintained, resulting in a high specific surface area. When 100 secondary particles were similarly observed with an SEM, they were all composite particle materials with the same porous microstructure. In other words, it was clear that the microstructure had not been disturbed by external stress.

[0091] Table 2 shows the average diameter and sphericity of secondary particles, and Table 3 shows the specific surface area, average pore diameter, average pore volume, and bulk density. Figure 5 shows the nitrogen adsorption isotherm. The average diameter of secondary particles was determined by randomly selecting 100 particles from the SEM image, calculating the average of (long side + short side) / 2 as the secondary particle diameter, and then calculating the average. The sphericity of secondary particles was determined by measuring the short side / long side of 100 particles and calculating the average. The upper limit is 1.0, and the closer to 1.0, the higher the sphericity. The bulk density of secondary particles was measured in accordance with JIS 1628-1997. The specific surface area, average pore diameter, and average pore volume were measured by the BET method immediately after heating in a vacuum at 110°C for 6 hours. Ti3Al 0.02 The mutual dispersion, which is the degree of dispersion of the primary particles of the C2MXene nanosheets and acetylene black as carbon microparticles, was measured. Specifically, it was quantified by Raman spectroscopy. The laser intensity was 100 cm at which anatase does not precipitate. -1 From 2000cm -1 Analysis was performed on 100 points within the range, and the standard deviation was calculated for the ratio of B peak intensity / A peak intensity to obtain the mutual dispersion. The obtained mutual dispersion is shown in Table 4. The obtained composite particle material was heat treated in a vacuum at 110°C for 5 hours, and the mass change was measured and shown in Table 5. The obtained composite particle material was also subjected to XRD measurement, and the profile is shown in Figure 3. From the results of the XRD measurement, the interlayer distance of the (002) plane of the MXene nanosheet is shown in Table 6. The obtained composite particle material was placed in a φ10 mm mold and heated at 0.5 kg / cm 2 Uniaxial pressing was performed at a pressure of 1.0 ton / cm. 2The surface electrical resistance was measured by a four-terminal method using copper wires of φ0.1 mm using a green compact that had been subjected to cold isostatic pressing (CIP) at a pressure of 1000 kJ / cm². The results are shown in Table 7.

[0092] Example 2 The composite particulate material was obtained in the same manner as in Example 1, except that the uniformly mixed dried powder was placed in an alumina crucible and fired in a graphite resistance furnace under Ar flow at 1430°C for 2 hours to obtain Ti3AlC2 as MAX phase ceramics. Measurements were performed in the same manner as in Example 1, and the results are shown in the figures and tables. Figure 6 shows an AFM image of the exfoliated MXene nanosheets, and Figure 7 shows an SEM image. Figure 8 shows the XRD profiles of the MAX phase ceramics and the composite particulate material, and Figure 9 shows an SEM image. Table 1 shows the average thickness and size of the exfoliated MXene nanosheets. Table 2 shows the average particle diameter and sphericity of the resulting composite particulate material. Table 3 shows the specific surface area, average pore diameter, average pore volume, and bulk density. Table 4 shows the interlayer dispersity. Table 5 shows the mass change. Table 6 shows the interlayer distance of the (002) plane of the MXene nanosheets, and Table 7 shows the surface electrical resistivity.

[0093] Example 3 The amount of acid-treated acetylene black added was Ti3Al 0.02 Composite particulate materials of MXene and acid-treated acetylene black were prepared in the same manner as in Example 2, except that the mass of the C2MXene nanosheets was 10 mass% based on the mass of the composite particulate materials. Table 2 shows the average particle diameter and sphericity of the obtained composite particulate materials, measured in the same manner as in Example 1, Table 3 shows the specific surface area, average pore diameter, average pore volume, and bulk density, Table 4 shows the mutual dispersity, Table 5 shows the mass change, Table 6 shows the interlayer distance of the (002) plane of the MXene nanosheets, and Table 7 shows the surface electrical resistivity.

[0094] Example 4 The amount of acid-treated acetylene black added was Ti3Al 0.02A composite particulate material of MXene and acid-treated acetylene black was prepared in the same manner as in Example 2, except that the amount of C2MXene nanosheets was 3 mass% based on the mass of the nanosheets. Measurements were performed in the same manner as in Example 1. The average particle diameter and sphericity of the obtained composite particulate material are shown in Table 2, the specific surface area, average pore diameter, average pore volume, and bulk density in Table 3, the mutual dispersity in Table 4, the mass change in Table 5, the interlayer distance of the (002) plane of the MXene nanosheets in Table 6, and the surface electrical resistivity in Table 7.

[0095] Example 5 Using 9.2 g of TiC powder (TI-30-10-0020, Rare Metallic Co., Ltd.), 3.2 g of TiN powder (TN-30-10-0020, Rare Metallic Co., Ltd.), 4.9 g of Ti powder (TIE07PB 3N, Kojundo Chemical Co., Ltd.), and 2.8 g of Al powder (ALE15PB 3NG, Kojundo Chemical Co., Ltd.) as starting materials, TiAl(C 0.75 N 0.25 )2 powder was prepared. XRD analysis confirmed that it was a MAX phase ceramic powder without impurities. This powder was used to prepare a composite particulate material in the same manner as in Example 1. Measurements were performed in the same manner as in Example 1. The average particle diameter and sphericity of the obtained composite particulate material are shown in Table 2, the specific surface area, average pore diameter, average pore volume, and bulk density in Table 3, the mutual dispersion in Table 4, the mass change in Table 5, and the interlayer distance of the (002) plane of the MXene nanosheet in Table 6.

[0096] (Comparative Example 1) The amount of acid-treated acetylene black added was Ti3Al 0.02 Composite particulate materials of MXene and acid-treated acetylene black were prepared in the same manner as in Example 2, except that the amount of C2MXene nanosheets was 2 mass% based on the mass of the nanosheets. Table 2 shows the average particle diameter and sphericity of the resulting composite particulate materials, measured in the same manner as in Example 1, Table 3 shows the specific surface area, average pore diameter, average pore volume, and bulk density, Table 4 shows the mutual dispersity, Table 5 shows the mass change, and Table 6 shows the interlayer distance of the (002) plane of the MXene nanosheets.

[0097] (Comparative Example 2) An ethanol slurry of the composite agglomerated particulate material was prepared in the same manner as in Example 2 up to the mixing and agglomeration steps. To further reduce the amount of water remaining in the solvent, the solvent was replaced from ethanol to IPA to prepare an IPA slurry of the composite agglomerated particulate material. The IPA slurry was subjected to centrifugal sedimentation (7900 G), and the sediment was air-dried for 12 hours at room temperature. This was then heat-treated in a vacuum at 60°C for 6 hours to obtain a mass of the composite agglomerated particulate material. This was then crushed by applying physical stress in a crusher consisting of a mortar and pestle to prepare the composite particulate material of this comparative example. The remaining steps were the same as in Example 1.

[0098] Measurements were performed in the same manner as in Example 1. The average particle diameter and sphericity of the obtained composite particle material are shown in Table 2, the specific surface area, average pore diameter, average pore volume, and bulk density in Table 3, the mutual dispersion in Table 4, the mass change in Table 5, the interlayer distance of the (002) plane of the MXene nanosheet in Table 6, and the surface electrical resistance in Table 7. Furthermore, 100 secondary particles were observed under SEM to examine the uniformity of their microstructures when crushed by applying physical stress. Most secondary particles maintained their aggregated structure, but the aggregated structure was destroyed in a few secondary particles (Figure 10).

[0099] (Comparative Example 3) A suspension of exfoliated material was obtained in the same manner as in Example 1 up to the peeling step. To 220 mL of the suspension of exfoliated material with a particle concentration of 15.6 mg / mL obtained in the peeling step, an alkaline aqueous solution was added, which had been prepared by dissolving 3.5 g of lithium hydroxide in 40 mL of pure water in advance and completely dissolving the solution by shaking at 140 rpm and 45 mm amplitude for 1 hour. The mixture was then stirred in a shaker at 140 rpm and 45 mm amplitude for 1 hour. The mixture was then washed with water once and substituted with ethanol three times. The mixture was then stirred in ethanol at 140 rpm for 6 hours to break down coarse aggregates, yielding an ethanol slurry of aggregates with a particle concentration of 5.0 mg / mL. The solvent was replaced with IPA in the same manner as in Comparative Example 2, producing an IPA slurry of composite agglomerated particle material. The IPA slurry was subjected to centrifugal sedimentation (7900 G) to settle the composite agglomerated particle material, and the precipitate was air-dried at room temperature for 12 hours. It was then dried in a vacuum at 60 °C for 6 hours to obtain a mass of composite agglomerated particle material. The mixture was then crushed by applying physical stress in a grinding machine consisting of a mortar and pestle to produce a composite particle material. The secondary particles thus produced were then mixed with 5% acid-treated acetylene black and N-methylpyrrolidone (NMP) based on the mass of MXene to produce a paste. The paste was produced in a grinding machine consisting of a mortar and pestle. The mixture was then dried in a vacuum at 110°C for 6 hours to remove the NMP, producing a composite particle material of MXene and acetylene black. The remaining steps were the same as in Comparative Example 2.

[0100] The average particle diameter and sphericity of the composite particle material obtained by measurement in the same manner as in Example 1 are shown in Table 2, the specific surface area, average pore diameter, average pore volume, and bulk density in Table 3, the mutual dispersion in Table 4, the mass change in Table 5, and the interlayer distance of the (002) plane in Table 6.

[0101] Comparative Example 4 The procedure up to the peeling step was the same as in Example 1, yielding 220 mL of a suspension of exfoliated material. 220 mL of IPA was added to prepare a slurry of MXene aggregate particles in a mixed solution of IPA and water. This was centrifuged (7900 G), and the resulting sediment was air-dried at room temperature for 12 hours. It was then dried in a vacuum at 60°C for 6 hours to obtain agglomerates. Secondary particles were then produced by applying physical stress and crushing using a grinder consisting of a mortar and pestle. The resulting secondary particles were then added to N-methylpyrrolidone (NMP) in which 5% acid-treated acetylene black was dispersed, based on the mass of MXene, to produce a paste. The paste was prepared using a grinder consisting of a mortar and pestle. The NMP was then removed in a vacuum at 110°C for 6 hours, yielding a composite particle material of MXene and acetylene black. The remaining steps were the same as in Comparative Example 3.

[0102] Measurements were performed in the same manner as in Example 1. The average particle diameter and sphericity of the obtained composite particle material are shown in Table 2, the specific surface area, average pore diameter, average pore volume, and bulk density in Table 3, the nitrogen adsorption isotherm in Figure 5, the mutual dispersity in Table 4, the mass change in Table 5, the interlayer distance of the (002) plane of the MXene nanosheet in Table 6, and the surface electrical resistance in Table 7.

[0103] [Table 1]

[0104] [Table 2]

[0105] [Table 3]

[0106] [Table 4]

[0107] [Table 5]

[0108] [Table 6]

[0109] [Table 7] This will be explained in detail using tables and figures. Table 4 shows Ti3Al 0.02 C2MXene (97.0-90.0 mass%) / carbon particles (3.0-10.0 mass%) composition, and Ti3Al 0.02 (C 0.75 N 0.25 The composite powder material, produced by spray-drying an alcohol slurry of agglomerated powder composed of 2MXene (95% by mass) and carbon microparticles (5.0% by mass), dries without shrinkage because the alcohol is instantly removed. As a result, the degree of mutual dispersion is remarkably excellent. The conductive carbon microparticles are uniformly distributed on the outer surface of the MXene nanosheets, enabling smooth transfer of electrons to the current collector.

[0110] From Table 2, Fig. 4, and Fig. 9, Ti3Al 0.02 C2MXene (97.0-90.0 mass%) / carbon microparticle (3.0-10.0 mass%) composition and Ti3Al 0.02 (C 0.75 N 0.25A composite powder material prepared by spray-drying an alcohol slurry of agglomerated powder composed of 2MXene (95% by mass) and carbon nanoparticles (5.0% by mass) had an average secondary particle size of approximately one micrometer and excellent sphericity. High-magnification SEM observation of 100 secondary particles revealed the 3D porous structure shown in Figures 4 and 9. On the other hand, when the agglomerated powder mass was air-dried and vacuum-dried at 60°C, and then crushed using a mortar and pestle under physical stress (crushing), as seen in the SEM image in Figure 10, finely crushed and uncrushed coarse particles coexisted, resulting in an amorphous structure. This prevented the formation of a uniform membrane for cell fabrication. Furthermore, high-magnification SEM observation of 100 composite powder samples was performed to determine whether the agglomerated structure had been destroyed by the application of physical stress. As shown in Figure 10, the agglomerated structure was destroyed in several samples. Prolonged application of physical stress to reduce the secondary particle size further destroyed the agglomerated structure.

[0111] Table 3 shows the physical values ​​of the 3D porous structure. 0.02 C2MXene (97.0-90.0 mass%) / carbon microparticle (3.0-10.0 mass%) composition and Ti3Al 0.02 (C 0.75 N 0.25 A composite powder material prepared by spray-drying an agglomerated powder alcohol slurry composed of 2MXene (95% by mass) and carbon nanoparticles (5.0% by mass) has a higher specific surface area, larger average pore diameter, and larger average pore volume than a composite particle material prepared by crushing the agglomerates through physical stress application. This is because the droplets of the agglomerated powder alcohol slurry dry instantly, suppressing shrinkage during drying. As shown in Table 1, MXene is exfoliated to a monolayer level, specifically, a thickness of 1.5 nm. Shrinkage during drying indicates adhesion between MXene nanosheets. Obtaining a composite powder material without shrinkage indicates that the composite powder material is prepared while maintaining the monolayer level of MXene nanosheets. Smooth ion diffusion allows for rapid charge / discharge, leading to excellent cycle characteristics and high capacity.

[0112] The effect of the average size of the MXene nanosheets on the physical values ​​of the 3D porous structure of the composite particle material after granulation will be specifically described. Comparing Example 1 and Example 2, Example 2 has a larger specific surface area. Lowering the firing (synthesis) temperature of the MAX phase ceramics within a range that does not generate impurities weakens the interlayer bonding force, and the average size decreases while maintaining a monolayer-level thickness during the exfoliation process. The smaller average size, approximately 0.2 μm (Example 2), had a larger specific surface area, smaller average pore diameter, and larger pore volume than the smaller average size, approximately 0.8 μm (Example 1).

[0113] As representative examples, adsorption isotherms for Examples 1 and 2 and Comparative Example 4 are shown in Figure 5. It is clear that the composite particulate material of the present invention is an excellent 3D porous material.

[0114] Table 5 shows the composite powder material of 0.3 g in a 20 cm 3 The mass change when the Ti3Al alloy was spread evenly on the plate and heated in a vacuum at 110°C for 5 hours is shown. 0.02 C2MXene (97.0-90.0 mass%) / carbon particles (3.0-10.0 mass%) composition, and Ti3Al 0.02 (C 0.75 N 0.25 )2 Composite powder material prepared by spray-drying an alcohol slurry of an agglomerated powder composed of MXene (95% by mass) and carbon microparticles (5.0% by mass) was vacuum-dried at 110°C to completely remove the water remaining between the MXene layers. On the other hand, composite particle material prepared by air-drying and then vacuum-drying at 60°C to crush the agglomerated masses under physical stress still contained a large amount of water remaining between the MXene layers. When the agglomerated masses were vacuum-dried at 110°C after air-drying, they significantly shrunk, resulting in a low specific surface area. While vacuum-drying at 110°C is typically performed after membrane fabrication in cell fabrication, it is difficult to completely remove the water between the MXene layers, resulting in problems such as deterioration of cycle characteristics.

[0115] The bulk density of the obtained composite particulate material is shown in Table 3. 0.02C2MXene (97.0-90.0 mass%) / carbon particles (3.0-10.0 mass%) composition, and Ti3Al 0.02 (C 0.75 N 0.25 A composite powder material prepared by spray-drying an alcohol slurry of agglomerated powder composed of 2MXene (95% by mass) and carbon microparticles (5.0% by mass) was compared with a composite particulate material prepared by pulverizing the agglomerates through physical stress application. The former has a 3D porous agglomerated structure, uniform secondary particle size, and spherical morphology, while the latter does not have a 3D porous agglomerated structure and is denser and more amorphous than the former, but is characterized by a continuous particle blend. This results in a lower bulk density for the former.

[0116] However, when producing cells such as secondary batteries, the former method produces a film with a uniform structure, which can improve the performance of the produced secondary battery, etc. To produce a high-density film, it is preferable to prepare composite particle materials with several different secondary particle sizes to achieve appropriate close packing, and to perform continuous particle blending, for which the Andreasen equation has proposed a distribution law for creating close packing, or to perform two-stage particle blending, in which two types of composite particle materials, coarse and fine, are blended.

[0117] Table 6 shows the interlayer distance of the (002) plane of MXene obtained by XRD of the composite particle material obtained. The composite particle material of the present invention, in which carbon nanoparticles are uniformly distributed, has a larger interlayer distance than the composite particle material of the present invention, in which agglomerated powder of MXene alone is prepared and then NMP is added to mix the carbon nanoparticles. This is because Li and / or Na ions and chlorine ions intercalate between the MXene layers during the process of uniformly distributing the carbon nanoparticles, widening the gap between the layers. The value obtained by subtracting the interlayer distance of the (002) plane of the MAX phase ceramic from the (002) plane of MXene can be considered the gap distance resulting from the removal of the Al phase from the MAX phase ceramic (see Figure 11). For the composite particle material of the present invention, the gap distance is approximately 0.6 nm. Ions larger than Li ions, such as Na ions, can be inserted and removed. Furthermore, the larger gaps enable rapid charging and discharging and have long lifespans.

[0118] Table 7 shows the surface electrical resistance of the compact. This was done to determine the oxidation state of the MXene nanosheet surface and the amount of water remaining between the layers. When the surface of the MXene nanosheet is oxidized, the electrical resistance increases. Furthermore, if there is water remaining between the layers, the surface resistance increases as time passes, as oxidation of the interlayer surface progresses. Therefore, if oxidation progresses or there is a large amount of water between the layers, the surface electrical resistance increases.

[0119] The surface electrical resistance of a powder compact is also affected by the number of contacts between powder particles. The number of contacts is indicated by the relative density of the powder compact. The relative density is determined by (bulk specific gravity / true specific gravity) x 100. For composite particle materials used as negative electrode active materials in secondary batteries or electrodes in electrochemical capacitors, the surface electrical resistance of the powder compact is preferably in the range of 1.0 to 100.0 Ω / □, as shown in Table 7.

[0120] As described above, it has been found that a composite particle material can be obtained in which MXene and microparticles are highly dispersed, an aggregated structure is maintained, and high sphericity is achieved. As disclosed in PCT / JP2021 / 018296, previously filed by the applicant, the original composite particle material has excellent ion diffusivity and can smoothly transfer electrons to a current collector, making it ideal for use as a negative electrode active material in secondary batteries (storage batteries) or as an ideal positive and / or negative electrode active material in pseudocapacitors. Therefore, since the 3D porous aggregated structure can be maintained, further improved ion diffusivity is expected, and since the sphericity can be increased, higher uniformity can be expected when the film is formed.

[0121] Furthermore, when a composite particulate material was produced using methanol or isopropanol instead of the ethanol used in Example 1, a composite particulate material similar to that used in Example 1 was obtained. Here, when isopropanol was used instead of the ethanol used in Example 1 to produce a composite particulate material, it was necessary to increase the spray temperature in the granulation process to 85°C. As in Example 1, the surface electrical resistance was measured to be 60.5 Ω / □, compared to 41.1 Ω / □ when ethanol was used, resulting in a slight increase in resistance. This is because slight oxidation progressed on the surface due to the slight increase in spray temperature. When a composite particulate material was produced using methanol instead of the ethanol used in Example 1, the spray temperature in the granulation process could be lowered to 75°C. As in Example 1, the surface electrical resistance was measured to be 40.7 Ω / □, which was almost the same as when ethanol was used. Based on these findings, any of ethanol, methanol, and isopropyl alcohol may be used as the solvent in the granulation process.

Claims

1. 3 to 10 parts by mass of conductive particles and Ti 3 Al a (C( 1 . 0-x ) N x ) 2 , (0≦x≦0.25, a is 0.01 or more) and 90 to 97 parts by mass of MXene nanosheets as primary particles, The MXene nanosheet has an average thickness of 1.0 to 3.5 nm; The primary particle diameter of the microscopic objects is 100 nm or less, A composite particle material having a mutual dispersion of 0.01 to 7.00, an average secondary particle diameter of 1.0 μm to 15.0 μm, and a sphericity of 0.8 or more. (mutual dispersion degree) In Raman spectroscopy using a 532 nm wavelength laser, -1 Peak height A and 1332 cm -1 The ratio (B / A) of the peak height B of the sample to the peak height B of the sample is calculated for 100 samples, and the standard deviation calculated from the 100 B / A values ​​is taken as the mutual dispersion.

2. 2. The composite particulate material according to claim 1, wherein the microparticles are carbon microparticles.

3. Specific surface area is 75m 2 3. The composite particulate material according to claim 1, wherein the particle size is 1.0 to 2.0 nm and the average pore volume is 0.30 to 0.70 mL / g or more.

4. A 0.3 g sample was placed on a 20 cm 2 4. The composite particulate material according to claim 1, wherein when the composite particulate material is uniformly spread on the above plate and heated in a vacuum at 110° C. for 5 hours, the change in mass is 1.0% by mass or less.

5. Bulk density of 0.1 to 0.5 g / cm 3 The composite particulate material according to any one of claims 1 to 4, wherein

6. The Ti 3 Al a (C( 1 . 0-x ) N x ) 2 (0≦x≦0.25, a is 0.01 or more) The average size of the MXene nanosheet in the spreading direction is 0.1 to 2.0 μm, 6. The composite particulate material according to claim 1, wherein the primary particle diameter of the microparticles is 30 to 50 nm.

7. The Ti 3 Al a (C( 1 . 0-x ) N x ) 2 7. A composite particle material according to any one of claims 1 to 6, wherein in the crystal structure of MXene, the interlayer distance of the (002) plane is 1.400 nm to 1.700 nm (0≦x≦0.25, a is 0.01 or more).

8. Ti with a zeta potential of -25.0 mV to -35.0 mV 3 Al a (C( 1 . 0-x ) N x ) 2 8. The composite particulate material according to claim 1, which is composed of MXene and carbon microparticles having a zeta potential of -20.0 mV to -25.0 mV (where 0≦x≦0.25 and a is 0.01 or more). (Zeta potential) The zeta potential is measured in water in the pH range of 6.0 to 8.

0.

9. 9. The composite particle material according to claim 1, having a surface electrical resistance of 1.0 Ω / □ to 100.0 Ω / □. (Surface Electrical Resistivity) After heat treatment in a vacuum at 110°C for 5 hours, the specimen was subjected to a pressure of 0.5 kg / cm in a φ10 mm mold. 2 Then, the pressure was 1.0 ton / cm. 2 The surface electrical resistance is measured by a four-terminal method using copper wires of 0.1 mm in diameter using a powder compact subjected to cold isostatic pressing at a pressure of 1000 kJ / cm2.

10. 10. A negative electrode for a secondary battery, comprising the composite particulate material according to claim 1 as a negative electrode active material.

11. 10. An electrode for a pseudocapacitor, comprising the composite particulate material according to claim 1 as an active material for a positive electrode and / or a negative electrode.

12. In a dispersion medium containing 50 mass % or more of water, 3 Al a (C( 1 . 0-x ) N x ) 2 a peeling step of peeling MXene to form a peeled product (where 0≦x≦0.25 and a is 0.01 or more); an acid treatment step in which the raw carbon particles are treated in a mixed acid solution of sulfuric acid and nitric acid at 70°C or higher for 10 minutes or more to obtain carbon particles; a mixing step of adding 0.8 to 1.0 mol / L of a water-soluble lithium salt and / or a water-soluble sodium salt to a mixture slurry of the exfoliated material and the carbon fine particles in a mass ratio of 90:10 to 97:3 and having a particle concentration of 11.5 to 17.0 mg / L, and stirring the mixture; An alkaline aqueous solution of 0.4 to 0.7 mol / L is added to the mixture slurry to make the liquid alkaline and cause coagulation. 3 Al a (C( 1 . 0-x ) N x ) 2 an agglomeration step of obtaining a slurry of agglomerates of MXene and the carbon microparticles, where 0≦x≦0.25 and a is 0.01 or more; a granulation step in which the dispersion medium of the slurry is replaced with alcohol to prepare an alcohol slurry of the aggregate, and the alcohol slurry is granulated by a spray drying method under an inert atmosphere to obtain granules; and The method for producing a composite particulate material, wherein the carbon microparticles have a primary particle diameter of 100 nm or less.

13. The method for producing a composite particulate material according to claim 12, wherein the alcohol is methanol, ethanol and / or isopropanol.

14. The method for producing a composite particulate material according to claim 12 or 13, further comprising a drying step of drying the granules at 100 to 120°C in an inert atmosphere.

15. The peeling step is performed by 3 Al a (C( 1 . 0-x ) N x ) 2 15. A method for producing a composite particulate material according to any one of claims 12 to 14, wherein the above-mentioned step (x≦0.25, a is 0.01 or more) is carried out until 99% or more of the exfoliated material is obtained by mass.

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