WO2023089739A1

WO2023089739A1 - Composite particle material, method for producing same, and electrode

Info

Publication number: WO2023089739A1
Application number: PCT/JP2021/042466
Authority: WO
Inventors: 仁俊佐藤; 実長田; 友祐渡辺; 寛之恩田; 亘孝冨田
Original assignee: 株式会社アドマテックス; 国立大学法人東海国立大学機構
Priority date: 2021-11-18
Filing date: 2021-11-18
Publication date: 2023-05-25
Also published as: JPWO2023089739A1

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

Composite particle material, manufacturing method thereof, and electrode

The present invention relates to a novel composite particle material of MXene nanosheets and microparticles, a method for producing the same, and an electrode using the composite particle material.

Conventionally, a particle material made of an MXene layered compound obtained by removing Al from a MAX phase ceramic powder such as Ti ₃ AlC ₂ which is a layered compound by acid treatment (in this specification, it is appropriately referred to as "MXene particle material" or " It is sometimes referred to as "MXene nanosheet", "layered compound particle material", or simply "particle material") (Patent Documents 1 to 6). These MXene layered compounds can store/desorb Na ions and Li ions in the void layer from which the Al layer has been removed. Positive and/or negative electrode active materials for pseudocapacitors (also called redox capacitors) that utilize electrochemical reactions involving faradaic currents associated with electrochemical adsorption and desorption reactions of ions at the electrodes, and Due to its excellent properties, it is expected to be applied to electromagnetic wave shielding thin films and conductive thin films.

MAX phase ceramics are layered compounds, and the general formula is expressed as M _n+1 AX _n . In the formula, M is a transition metal (Ti, Sc, Cr, Zr, Nb, etc.), A is an A group element, X is C or [C _(1.0-x) N _x (0<x≦1.0)] , n is 1 to 3.

Among them, when A is Al, the bond of MA is weaker than that of MX, so the Al layer is selectively removed by acid treatment. The present inventors have proposed a method of preparing MXene nanosheets by exfoliating them with a bead mill using micro-sized beads (Patent Documents 5 and 6).

Japanese Patent Application Laid-Open No. 2016-63171 JP 2017-76739 A U.S. Patent Application Publication No. 2017/0294546 U.S. Patent Application Publication No. 2017/0088429 Japanese Patent No. 6564553 Japanese Patent No. 6564552

Here, when MXene nanosheets are used in secondary batteries (storage batteries) and pseudocapacitors, not only MXene nanosheets but also acetylene black is added as a conductive aid. In order to improve battery characteristics such as cycle characteristics (lifetime characteristics), rapid charge/discharge characteristics, and capacity, it is necessary to increase ion diffusibility and move electrons smoothly to the current collector. Specifically, it is required to exfoliate the nanosheets to a single layer level, increase the specific surface area of the composite particle material of the MXene nanosheet and the conductive microparticles, and to arrange the conductive microparticles uniformly between the nanosheets. be done. As a result of intensive studies, we succeeded in obtaining a composite particle material of MXene nanosheets and conductive microparticles that is effective as a secondary battery (storage battery) negative electrode active material, or as a positive electrode and/or negative electrode active material for a pseudocapacitor.

The composite particle material previously filed by the present applicant is an aggregate of primary particles. Therefore, pulverization and classification are essential for industrial use. When pulverization, which is generally performed by applying physical stress to agglomerates, it seems possible to pulverize them to a particle size that can be used in practice, but it was found that the agglomerate structure was locally destroyed. . Furthermore, it has been found that the strength of aggregates is affected by the humidity environment, and thus the aggregate structure obtained differs depending on the season, making it impossible to obtain an industrially usable composite particle material. If the part where the agglomeration structure is destroyed is used for the electrode of a secondary battery or a pseudocapacitor, the characteristics will be significantly deteriorated, and if the crushing that applies physical stress is performed, the particle shape will become irregular and uniform at the time of electrode preparation. However, there were problems such as the inability to form a thin film.

The present invention has been completed in view of the above circumstances, and provides a powder having a 3D porous aggregation structure with a high specific surface area, in which the novel MXene nanosheets and microparticles are highly dispersed, and which has a high sphericity. The problem to be solved is to provide a particulate material, a method for producing the same, and an electrode using the composite particulate material.

The composite particle material of the present invention, which solves the above problems, contains 3 to 10 parts by mass of conductive microparticles and Ti ₃ Al _a (C( _1.0 _-x )N _x ) ₂ , (0 ≤ x ≤ 0 .25, a is 0.01 or more) MXene nanosheets containing 90 to 97 parts by mass as primary particles, the MXene nanosheets having an average thickness of 1.0 to 3.5 nm, and having the following interdispersion degree: It has a volume average diameter 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.

(interdispersion degree)
Calculate 100 ratios (B/A) of peak height A at 400 cm ⁻¹ and peak height B at 1332 cm ⁻¹ in Raman spectroscopic analysis using a laser with a wavelength of 532 nm, and the 100 B/A values The standard deviation calculated from is taken as the degree of interdispersion.

The method for producing a composite particle material of the present invention that solves the above _problems comprises: _Ti3Ala (C( _1.0 _-x ) _Nx ) ₂ , (0≤ x ≤ 0.25, a is 0.01 or more) a stripping step of stripping MXene to form a stripped product;
an acid treatment step of treating raw carbon microparticles in a mixed acid aqueous solution of sulfuric acid and nitric acid at 70° C. or higher for 10 minutes or longer to obtain carbon microparticles;
The particle concentration is 11.5 to 17.0 mg / L, and 0.8 to 1.0 mol / L of A mixing step of adding and stirring a water-soluble lithium salt and/or a water-soluble sodium salt;
An alkaline aqueous solution of 0.4 to 0.7 mol/L is added to the mixture slurry to make the liquid alkaline and aggregate to form the Ti ₃ Al _a (C( _1.0 _-x )N _x ) ₂ , (0≦x≦0.25, a is 0.01 or more) an aggregation step of obtaining a slurry of aggregates of MXene and the carbon fine particles;
A granulation step of obtaining granules by granulating an alcohol slurry of the aggregates prepared by replacing the dispersion medium of the slurry with alcohol by a spray drying method under an inert atmosphere;
have

By having the above structure, the composite particle material of the present invention can provide an electrode that can exhibit high performance when used in secondary batteries (storage batteries) and pseudocapacitors by adopting it as an active material.

In addition, the method for producing a composite particle material of the present invention makes it possible to produce a composite particle material having an ideal 3D porous aggregation structure and a high degree of sphericity by using the production method having the above configuration. .

4 is an AFM image of a peeled product obtained in the peeling step of Example 1. FIG. 4 is an SEM photograph of a peeled product obtained in the peeling step of Example 1. FIG. 2 is the XRD profile of Ti ₃ AlC ₂ and composite powder material of Example 1. FIG. 1 is a SEM photograph of the composite powder material of Example 1. FIG. 2 shows adsorption isotherms of composite powder materials of Example 1, Example 2 and Comparative Example 4. FIG. 4 is an AFM image of a peeled product obtained in the peeling step of Example 2. FIG. 4 is an SEM photograph of a peeled product obtained in the peeling step of Example 2. FIG. 2 is the XRD profile of Ti ₃ AlC ₂ of Example 2 and the composite powder material. 4 is an SEM photograph of the composite powder material of Example 2. FIG. 4 is an SEM photograph of the composite powder material of Comparative Example 2. FIG. FIG. 2 is a schematic diagram showing a unit cell of MAX phase (Ti ₃ AlC ₂ ).

The composite particle material, manufacturing method thereof, and electrode material of the present invention will be described in detail below based on embodiments. The composite particle material of the present embodiment has excellent electrical properties such as conductivity, and has a large void layer formed in the crystal due to the removal of the Al layer. secondary batteries, Na-ion secondary batteries, etc.), active materials such as 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 and conductive thin films Application to materials is possible. In addition, the numerical values described in this specification can be used as upper and lower limits of numerical ranges, and in such cases, the range can be either inclusive or exclusive of the numerical values.

(Composite particle material)
The composite particle material of the present embodiment is a particle material obtained by combining a thin piece of MXene and a particulate or tube-like minute body for application to an electrode material or the like. MXene exfoliated particulate material is obtained by exfoliating multi-layer MXene, which is a powdery layered compound of several microns.

In this specification, when a plurality of upper limit values and lower limit values are set for a certain parameter, those upper limit values and lower limit values can be arbitrarily combined unless otherwise specified. The composite particle material of this embodiment is a composite particle material of MXene and microparticles.

MXene contains 90 to 97% based on the sum of the mass of MXene and minute bodies, and the remaining 10% to 3% is minute bodies. If the content of MXene exceeds 97%, the effect as a barrier against drying shrinkage due to the addition of fine particles is weakened, and if the content is lower than 90%, the function as an active material deteriorates. Furthermore, when the content of MXene exceeds 97%, electrons are difficult to move to the current collector, and when it is less than 90%, the function as an active material deteriorates. The lower limits of the MXene content are 93%, 92% and 90%, and the upper limits are 97%, 96% and 95%.

The composite particulate material has a mutual dispersity of 0.01 to 7.00. The interdispersion degree is a value that defines the degree of dispersion between the MXene and the minute particles. When carbon microparticles are used as the microparticles, the degree of interdispersion of 100 randomly selected composite particle materials was determined by Raman spectroscopic analysis using a laser with a wavelength of 532 nm with a peak height A of 400 cm ⁻¹ and The standard deviation calculated from the ratio (B/A) of the peak heights B at 1332 cm ^-1 is defined as the degree of interdispersion. It is desirable that the interdispersion degree is small, and if it exceeds 7.00, electrons cannot effectively move to the current collector. The interdispersion degree of the composite particle material can adopt lower limits of 0.01, 0.05, 0.10 and upper limits of 7.00, 2.50, 1.50. . _Ti3Ala (C( _1.0 _-x ) _Nx ) ₂ , (0≤x≤0.25, a is 0.01 or more) MXene nanosheet exfoliated to the monolayer level can be _easily oxidized to precipitate anatase, analyze at a laser intensity that does not precipitate anatase. Analysis is performed in the range from 100 cm ^-1 to 2000 cm ^-1 . Ti ₃ Al _a (C( _1.0 _-x )N _x ) ₂ , (0≦x≦0.25, a is 0.01 or more) Vibration due to functional groups adsorbed on titanium atoms of MXene nanosheet is 230 to 470 cm. At ⁻¹ (A peak), vibration due to functional groups adsorbed on carbon atoms appears at 580 cm ⁻¹ . On the other hand, for acetylene black, the SP3 hybrid orbital carbon appears at 1332 cm ⁻¹ (B peak), and the SP2 hybrid orbital carbon appears at 1500 to 1600 cm ⁻¹ .

The composite particulate material has a specific surface area of 75 m ² /g or more. The specific surface area is measured by the BET method using nitrogen after heating at 110° C. for 6 hours in vacuum as a pretreatment. For the specific surface area of the composite particle material, 75 m ² /g, 80 m ² /g and 105 m 2 /g can be adopted as lower limits, and 200 m ² /g, 185 m ² ^/ g and 170 m ² /g as upper limits. can be adopted. The composite particulate material preferably has an average pore diameter of 10.0-20.0 nm and an average pore volume of 0.30-0.70 mL/g. More preferably, the average pore diameter is 10.0-15.0 nm and the average pore volume is 0.40-0.60 mL/g. The average pore diameter and pore volume were measured by the BET method using nitrogen after heating in vacuum at 110° C. for 6 hours as a pretreatment.

In PCT/JP2021/018296 previously filed by the present applicant, a slurry of agglomerated particulate material is prepared in a liquid, centrifugally sedimented, the sediment is air-dried at room temperature, and then vacuum-dried at 60°C to prepare agglomerates. and then pulverized by applying physical stress to produce a composite particulate material that is secondary particles. It takes more than 24 hours to air dry. It shrinks during air drying and vacuum drying at 60°C. As for the shrinkage mechanism, the MXene nanosheets are overlapped and integrated, and at the same time, the carbon particles added as a shrinkage barrier move. Such a mechanism lowers the degree of interdispersion and lowers the specific surface area. Furthermore, the average pore diameter and average pore volume are also reduced. After air-drying, if it is dried in a vacuum at 110°C, it will shrink significantly and the specific surface area will decrease significantly. On the other hand, when a slurry of composite aggregated particles in an alcohol solvent is spray-dried, the droplets are dried instantaneously without shrinkage, resulting in a spherical composite particle material having a 3D porous aggregate structure with excellent interdispersion and a high specific surface area. Obtainable. In the method of obtaining a composite particle material by spray drying, which dries instantly, the specific surface area is reduced compared to the general method of obtaining a composite particle material, which is secondary particles, by applying physical stress to agglomerates. As the size increases, the average pore diameter and average pore volume increase. The 3D porous aggregation structure means a structure in which pores are formed in a three-dimensional network by aggregation of primary particles with interstices.

The composite particle material preferably has a mass change of 1.0% or less when 0.3 g of a sample is evenly spread on a dish of 20 cm ² or more and heated at 110° C. in vacuum for 5 hours. Under this heating condition, the water contained in the MXene layers and the water adhering to the outer surface volatilize, but by specifying the amount, it is possible to define a composite particle material with a low water content between the layers. As the mass change, upper limits of 0.8%, 0.6%, 0.4%, and 0.2% can be adopted. The mass change within the specified range means the amount of moisture adsorbed from the air on the outer surface of the composite particulate material, not the water in the MXene layers. If moisture remains between the layers of MXene, the cycle characteristics of secondary batteries and pseudocapacitors are degraded. The water remaining between the layers cannot be completely removed by heat treatment in a vacuum after fabrication of a secondary battery or pseudocapacitor cell. After spray drying, the composite particulate material is preferably dried at 100-120° C. under vacuum or inert atmosphere.

The composite particulate material preferably has a bulk density of 0.1-0.5 g/cm ³ . As lower limits, 0.1 g/cm ³ and 0.15 g/cm ³ can be adopted, and as upper limits, 0.45 g/cm ³ and 0.50 g/cm ³ can be adopted. There is no particular limitation on the method for producing an electrode film when producing a cell of a secondary battery or a pseudocapacitor, but it is preferable to produce the composite particle material to be contained so that the volume packing density is as high as possible.

For example, using general-purpose technology, continuous particle blending (particle size of compounded composite particle material mean that the particle size distribution changes continuously, and the particle size distribution is relatively broad). can be formed by mixing a composite particle material having

MXene is a formula representing the aforementioned MAX phase, M _n+1 AX _n (M is a transition metal, A is an A group element, X is C, or [C _(1.0-x) N _x (0<x≦1. 0)] and n is obtained by using Al as A in 1 to 3) and removing the Al phase by acid treatment. Among them, _Ti3Ala (C( _1.0 _-x ) _Nx ) ₂ , (0≤x≤0.25, a is 0.01 or _more ) is preferable. The lower limit of a can be 0.002. More preferably, the upper limit of a is 0.05. When x exceeds 0.25, the bead mill treatment using microbeads promotes microparticulation rather than exfoliation, making it impossible to obtain thin and large nanosheets. In addition to these elements, it can have O, OH, and halogen groups as surface functional groups.

MXene has a plate-like, leaf-like, flake-like, sheet-like, etc., and is generically defined as sheet-like. In MXene, the stacking direction of the layers of the stratified compound is defined as "thickness", and countless directions perpendicular to the thickness are defined as "sheet spread directions". The MXene has an average thickness of 1.0 to 3.5 nm, preferably 1.5 to 3.0 nm. The average thickness is calculated as the average value of 100 randomly selected particles measured by AFM analysis using a hydrophilized Si wafer. The size of the sheet can be measured by dropping a nanosheet onto a hydrophilized Si wafer and using an SEM. The average size of the sheet in the spreading direction is preferably 0.1 to 2.0 μm, more preferably 0.1 to 1.7 μm. When the maximum value in the direction perpendicular to the thickness is the “long side” and the minimum value is the “short side”, 100 randomly selected particles were measured by SEM, [(long side + short side) / 2 ] is taken as the average size in the spreading direction. _Ti3Ala (C( _1.0 _-x ) _Nx ) ₂ , ₍ 0≤x≤0.25, a is _0.01 or more) In _MXene , _{Ti3Al0.02C2MXene} has an average thickness of 1 .74 nm with an average size of 0.78 μm, but replacing 5% of the carbon sites with nitrogen gives an average thickness of 1.66 nm with an average size of 1.17 μm with 25% of the carbon sites replaced with nitrogen. , the average thickness is 1.81 nm and the average size is 1.61 μm. Replacing the carbon sites with nitrogen facilitates the formation of functional groups in water, lowering the interlayer bonding strength of MXene and yielding larger nanosheets at monolayer-level thicknesses. In addition, if the firing (synthesis) temperature of MAX phase ceramics is lowered within a range that does not generate impurities, the bonding strength between layers decreases, so it is possible to reduce the average size while maintaining the thickness at the monolayer level. becomes. For example, in Ti ₃ Al _0.02 C ₂ MXene, if the firing (synthesis) temperature of MAX phase ceramics is lowered from 1450° C. to 1430° C., the average thickness can be reduced to 2.06 nm and the average size to 0.25 μm. can. When the temperature is further lowered to 1410° C., the average thickness can be reduced to 1.98 nm and the average size to 0.10 μm.

If the MXene nanosheet exfoliated to the monolayer level is made into a composite particle material without shrinkage, an electrode material with excellent ion diffusion can be obtained. Furthermore, a composite particle material with a high specific surface area can be obtained by using MXene nanosheets of an appropriate size. A composite particle material with a higher specific surface area can be obtained by reducing the average size while maintaining the thickness at the monolayer level.

The interlayer distance of the (002) plane of MXene obtained from XRD analysis is preferably from 1.400 nm to 1.700 nm. The inter-layer distance of the void layer formed by removing the Al phase of the MAX phase by acid treatment is determined from the inter-layer distance of the (002) plane in the XRD of the MXene nanosheet powder to the (002) When defined as a value obtained by subtracting the interlayer distance of the plane, it is 0.770 nm to 0.470 nm. The Li ion diameter is 0.18 nm and the Na ion diameter is 0.28 nm, and can be used as a negative electrode active material for Na ion secondary batteries in addition to Li ion secondary batteries. Since the interlayer distance between the (002) planes of graphite powder is 0.33 nm, repeated insertion and desorption of Na ions causes rapid deterioration in a short period of time, and it was concluded that it cannot be used for Na ion secondary batteries. there is This is the reason why MXene nanosheets are particularly expected as a negative electrode active material for Na-ion secondary batteries. If the gap is large, expansion and contraction caused by the ingress and egress of ions are less likely to occur, so that the battery can be used without cycle deterioration even during rapid charging and discharging. Here, the _{corresponding} MAX phase ceramic powder is a particle material composed of a material having a value of 1 in the composition _Ti3Ala (C( _1.0 _-x ) _Nx ) ₂ of MXene to be measured. be. If the interlayer distance between the (002) planes of MXene nanosheets is less than 1.400 nm, deterioration occurs due to rapid charging and discharging when used as a negative electrode active material for Na-ion secondary batteries. If it exceeds 1.700 nm, the capacity per 1 g becomes small.

It is sufficient for the microscopic object to have a size on the order of nanometers, and being on the order of nanometers means that the length of 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, and fibrous.

The fine particles preferably have a primary particle size of 100 nm or less, preferably 30 to 50 nm, and more preferably 30 to 40 nm, and may be aggregates. The shape of the microscopic object is not limited, and spherical, sheet-like, tube-like, hollow, and irregular shapes can be exemplified.

In particular, minute bodies have electrical conductivity. Examples of microscopic bodies include carbon microscopic bodies made of carbon materials and metal microscopic bodies made of metal materials. As the fine carbon particles, it is preferable to use those having high conductivity such as acetylene black, ketschen black, carbon nanotubes, graphene, carbon fiber, graphite powder, and hard carbon powder. In addition to carbon microscopic bodies and metal microscopic bodies, inorganic microscopic bodies composed of other inorganic substances can also be used as microscopic bodies. TiO ₂ , Al ₂ O ₃ , SiO ₂ and BaTiO ₃ having a primary particle size of 100 nm or less can be used as the inorganic fine particles.

(Manufacturing method of composite particle material)
The method for producing a composite particulate material of the present embodiment includes a peeling step, a mixing step, an aggregating step, a granulating step, and other necessary steps. The method for producing the composite particulate material of the present embodiment is a production method that can be suitably employed for the production of the above-described composite particulate material of the present embodiment.
・Exfoliation step In the exfoliation step, microbeads are collided between the layers of multi-layered MXene, which are particles of several microns in size, in a dispersion medium to exfoliate them to obtain a nanosheet-like exfoliated slurry. be. Delamination proceeds between the layers of each layer of layered multilayer MXene. The stripped material is not particularly limited, but one having about 1 to 3 layers is preferable.

The resulting exfoliated material becomes an exfoliated material suspension suspended in a dispersion medium. This exfoliated material suspension can be directly subjected to the mixing step, or can be subjected to the mixing step after removing the dispersion medium. Although the method for obtaining the particulate and layered multilayer MXene as a material is not particularly limited, the following method can be exemplified.

MXene is obtained by acid-treating a raw material consisting of Ti 3-layer MAX phase ceramic powder and partially dissolving the Al layer. An example of a method for manufacturing MXene will be described later as a pretreatment step. The raw material to be subjected to the peeling step can employ those having the same composition as the material constituting the aforementioned particulate material. The composition does not substantially change in the stripping process.

A portion of Al is dissolved in this particulate material by acid treatment to form a multi-layered MXene that is particulate and layered with a size of several microns. After that, an exfoliated material suspension in which nanosheet-like exfoliated material of MXene is suspended is obtained by a detachment step of bead mill treatment with high-speed rotation using beads of 10 μm to 300 μm.

The dispersion medium for the stripping step is not particularly limited, but preferably contains 50% by mass or more of water, and contains alcohols such as methanol, ethanol, and isopropanol, methyl ethyl ketone, acetone ketones, dimethylformamide, dimethyl sulfoxide, and the like. be able to. It is more preferable to make water 100% by mass.

The concentration of MXene in the mixture for the stripping process is not particularly limited, but can be about 10.0 mg/mL to 20.0 mg/mL. Although there are no particular restrictions on the liquid properties of the mixed liquid, the pH can be adjusted to approximately 6.0 to 8.0.

The specific bead mill processing in the peeling process will be explained. By centrifugal separation, a bead mill equipped with a mechanism for classifying fine beads and a slurry mixture can be used to separate them. The exfoliated material exfoliated by the bead mill treatment can be optionally separated from the mixture before exfoliation by centrifugation, and finally all MXene can be exfoliated.

For example, the lower limit of the bead size can be 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, and the upper limit can be 300 μm, 200 μm, 100 μm. When it is 10 µm or more, it is easy to classify beads and slurry. The use of beads of 300 μm or less allows delamination to proceed in preference to reducing the size of the particulate material. Any combination of these lower and upper limits can be employed. If the size of the beads is in the proper range, the energy to be applied can be increased and the peeling can proceed preferentially.

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 particularly high fracture toughness, is preferred. On the other hand, with commonly used bead mills that classify beads and slurries in micro-sized gaps using beads larger than 300 μm, size reduction of the particulate material progresses in preference to exfoliation. Ball milling, such as planetary ball milling with beads and balls greater than 300 μm, also favors exfoliation by reducing the size of the particulate material. As a result, only a part of the particles can be separated, and a part of the particles must be separated by centrifugal separation.

Furthermore, MXene has been conventionally exfoliated by ultrasonic irradiation. When the solvent is irradiated with ultrasonic waves, cavitation is generated, and due to the crushing of the cavitation, the layers constituting the layered compound are exfoliated by the mechanism of powder collision. However, even if water, which tends to cause cavitation, is used, peeling progresses only in part, and it cannot be said that it is at a level that can be used in industry. Even in the method using a planetary ball mill, of course, peeling occurs in part, pulverization takes precedence, and surface oxidation proceeds remarkably due to the temperature rise. For this reason, a method of exfoliating only a part by ultrasonic irradiation and collecting by centrifugal separation has been adopted.

A peripheral speed of 6 m/sec to 12 m/sec can be adopted for the peripheral speed in the peeling process. A peripheral speed of 8 m/sec to 10 m/sec is more preferable. If it is 6 m/sec or more, the peeling efficiency is good, and if it is 12 m/sec or less, the application of excessive energy is suppressed, and the temperature rise of the obtained particle material can be suppressed, so that the surface of the obtained particle material is oxidized. Progression can be suppressed, and electrical resistance can be lowered. A slurry feed rate of 100 mL/min to 300 mL/min can be adopted. A slurry particle concentration of 10.0 mg/mL to 20.0 mg/mL can be adopted.

If the concentration is 10.0 mg/mL or less, the production efficiency of the MXene nanosheets will be poor, and if the concentration is 20.0 mg/mL or more, peeling will not proceed sufficiently, so this range is preferable.

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

40% to 80% can be used for the filling amount of beads. When it is 40% or more, the efficiency of stripping is improved, and when it is 80% or less, it becomes easy to classify beads and slurry. Whether or not the desired particle material containing many sheet-like particles has been produced can be determined by observation with SEM, TEM, or the like. In particular, the thickness of the particulate material can be determined by AFM analysis. The particulate material obtained in the exfoliation step can be used after being classified by a method such as centrifugation, if necessary. Optimal conditions in the peeling process vary depending on the size of the apparatus, so these numerical values are not limited.

It is preferable that 98% or more of the MXene on a mass basis is turned into the exfoliated material by the bead mill treatment, more preferably 99% or more of the exfoliated material, and still more preferably 100% of the exfoliated material. When the peeling process is completed under the condition that all the MXene becomes the peeled substance, it becomes possible to use the MXene which is not peeled off as it is in the mixing process without removing it. When removing MXene other than exfoliated matter, it can be separated by centrifugation, filtration, or the like.

The zeta potential of the exfoliated MXene obtained is measured in water of pH 6 to pH 8. The zeta potential is measured at pH 7 unless there is a particular problem. The zeta potential is preferably -25.0 mV to -35.0 mV. More preferably -28.0 mV to -34.0 mV. The zeta potential of Ti ₃ C ₂ MXene nanosheets was −28.9 mV. The nanosheet in which 3% of the carbon sites are replaced with nitrogen is -29.3 mV, the nanosheet in which 5% of the carbon sites are replaced with nitrogen is -31.5 mV, the nanosheet in which 10% of the carbon sites are replaced with nitrogen is -32.1 mV, and the carbon sites The nanosheet in which 15% of the carbon sites were replaced with nitrogen was −32.4 mV, and the nanosheet in which 25% of the carbon sites were replaced with nitrogen was −33.1 mV. The magnitude of the absolute value of the zeta potential can be rephrased as the amount of functional groups attached in water. When many functional groups in water are attached, the absolute value of zeta potential increases. Formation of suitable functional groups in water provides excellent releasability. The zeta potential of MXene nanosheets and carbon microparticles is negative zeta potential explained in the mixing step. It is immobilized with Li ions and/or Na ions. A moderate zeta potential is necessary, and if the absolute value of the zeta potential is small, the resulting composite particle material will have a low degree of interdispersion and a low specific surface area. If the absolute value of the zeta potential is large, it becomes difficult for electrons to move. Therefore, it is preferable to select MXene nanosheets and carbon microparticles that have an appropriate absolute value of the zeta potential.

For the chemical composition of the MXene nanosheets, the atom% of Ti, Al, C, and N was used to calculate the amounts of Al, C, and N when Ti was 3. For chemical analysis, weigh the sample in a platinum dish, add nitric acid + sulfuric acid + hydrofluoric acid, heat (about 120 ° C) to dissolve, and then heat at a high temperature (300 ° C) to mix nitric acid and hydrogen fluoride. A sample solution (sulfuric acid) was prepared by removing the acid, and the prepared sample solution was appropriately diluted and quantitatively analyzed by ICP.

Acid treatment step The acid treatment step is a step of treating the raw carbon microparticles with a mixed acid solution of sulfuric acid and nitric acid to obtain highly hydrophilic carbon microparticles. Examples of raw carbon fine particles include acetylene black, ketschen black, carbon nanotube, graphene, carbon fiber, graphite powder, and hard carbon powder. Acetylene black, Ketsujen black, and carbon nanotubes are more preferred from the viewpoint of conductivity, and acetylene black is more preferred from the viewpoints of both conductivity, purity, and price.

In the acid treatment step, a suspension of carbon microparticles suspended in the mixed acid is obtained, which can be used as it is in the mixing step, or the mixed acid can be washed repeatedly with water or the like to remove as much as necessary and used as carbon microparticles. can also Washing can be performed until the pH of the washing solution reaches about 6, and further until the pH reaches about 6.5, 7, or 8.

By this treatment, functional groups such as COOH groups and CO groups are introduced to the surface of the carbon microparticles to make them hydrophilic. The carbon microparticles after treatment become a carbon microparticle suspension dispersed in the mixed acid. It does not matter whether it is performed between the acid treatment process and the stripping process.

The treatment temperature is preferably 70°C or higher. In particular, it is preferable to set the temperature to 95° C. or lower so as not to cause boiling. The treatment time is not particularly limited, but hydrophilization can be ensured by treatment for 10 minutes or longer. Stirring or ultrasonic irradiation can be performed during the treatment. After the treatment, it may be subjected to the mixing step as it is, or the acid may be neutralized or separated. If the acid is neutralized or separated and the pH reaches a predetermined value or higher, the fine carbon particles aggregate, so neutralization can be carried out to the extent that the pH does not reach the predetermined value. As a method of separating the acid, a method of separating the solid content by a classification operation such as centrifugation can be exemplified.

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

The obtained hydrophilic carbon microparticles preferably have a zeta potential of -20.0 mV to -25.0 mV in water of pH 6 to pH 8. The zeta potential becomes negative because COOH and CO are adsorbed as functional groups. When the absolute value is smaller than −20.0 mV, positively charged Li ions in water due to the addition of water-soluble Li salts and/or water-soluble Na salts with MXene nanosheets, which is a negative zeta potential explained in the mixing step. And/or it cannot be immobilized by Na ions, resulting in a composite particle material with a low interdispersion degree and a low specific surface area. It is preferable to select MXene nanosheets and carbon microparticles having moderate absolute values of zeta potential.

・Mixing process In the mixing process, the mass ratio of the exfoliated matter and the carbon particles is 90:10 to 97:3, the concentration of the exfoliated matter is 11.5-17.0 mg/mL, and water is contained in an amount of 50% by mass or more. It is a step of obtaining a mixture dispersed in a second dispersion medium. More preferably, the second dispersion medium contains 100% by mass of water. By including other substances in the mixture, those substances can also be incorporated into the composite particulate material.

In particular, by allowing Li ions and Na ions to coexist, it is possible to immobilize the MXene and carbon microparticles that constitute the exfoliated material. Specifically, the negatively charged functional groups in water adsorbed to MXene and the negatively charged functional groups in water adsorbed to carbon microparticles are immobilized with positively charged Li ions and/or Na ions in water. is preferred. 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. If a water-soluble salt of a strong alkali or strong acid is added and stirred for a long time, the MXene nanosheets and the water-soluble salt may react with each other, and lithium titanate or sodium titanate may precipitate locally on the MXene surface. Water-soluble salts that remain neutral are preferred. It is preferable to add a water-soluble salt to the aqueous slurry of MXene in an amount of 0.8 mol/L to 1.0 mol/L. If it is less than 0.8 mol/L, it cannot be sufficiently immobilized, and if it exceeds 1.0 mol/L, many surplus ions remain. The mixture contains exfoliate 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 and the solvent that can be used in other processes. When the exfoliated material suspension obtained in the exfoliation step is directly subjected to the mixing step, the second dispersion medium contains the dispersion medium used in the exfoliation step. The reason why the MXene particle concentration in the composite slurry is limited to 11.5-17.0 mg/mL is that if it falls below 11.5 or exceeds 17.0, the specific surface area of the composite particle material obtained in the aggregation step described later This is because the

For the acid-treated carbon microparticles, add a predetermined amount of carbon microparticles to pure water, and rotate at a rotation speed of 100 rpm to 300 rpm and an amplitude of 40 mm to 50 mm, more preferably at a rotation speed of 100 rpm to 200 rpm and 45 mm to 50 mm. It is preferable to add the deaggregated carbon fines water slurry to the MXene water slurry and mix them by stirring with a shaker for 12 hours or more under the amplitude condition of . The conditions of the shaker at that time are preferably 100 to 300 rpm rotation speed and 40 to 50 mm amplitude. More preferably, the rotation speed is from 100 rpm to 200 rpm and the amplitude is from 45 mm to 50 mm. MXene Acid-treated carbon microparticles Water slurry and water-soluble salt are added at the same time, and stirred for 4-6 hours using a shaker at a rotation speed of 100 rpm to 300 rpm and an amplitude of 40 mm to 50 mm. Thus, it is more preferable to obtain an aqueous slurry of composite aggregated particles in which MXene nanosheets, Na and/or Li ions and carbon microparticles are uniformly arranged and uniformly dispersed in the liquid. In both cases, if the rotational speed exceeds 300 rpm, the nanosheets are likely to be destroyed, and if the rotational speed is less than 100 rpm, uniform mixing cannot be achieved. If the amplitude exceeds 50 mm, the nanosheets are likely to be destroyed, and if it is less than 40 mm, uniform mixing cannot be achieved.

Aggregation step In the aggregation step, a 0.4 to 0.7 mol / L alkaline aqueous solution is added to the mixture slurry obtained in the mixing step, and the pH of the liquid is increased to remove the exfoliated material contained in the mixture. This is a step of aggregating the carbon particles to form aggregates dispersed in the liquid. It is preferable to raise the pH to about 12-14.

The alkaline aqueous solution is preferably lithium hydroxide and/or sodium hydroxide. The pH is raised by adding an alkaline substance or by removing or diluting an acidic substance. It is preferable to increase the pH by adding the alkaline aqueous solution in several seconds and stirring within 1 hour with a shaker at a rotation speed of 100 rpm to 300 rpm. The amplitude of the shaker at that time is preferably 40 mm to 50 mm. In both cases, when the rotational speed is 300 rpm or less, the destruction of the nanosheets is suppressed, and when it is 100 rpm or more, uniform mixing can be easily performed.

When the amplitude is 50 mm or less, the destruction of the nanosheets is suppressed, and when it is 40 mm or more, uniform mixing can be easily achieved. It is more preferable to stir with a shaker with a rotation speed of 100 rpm to 200 rpm and an amplitude of 45 mm to 50 mm within 1 hour. The alkaline aqueous solution is preferably added in an amount of 0.4 mol/L to 0.7 mol/L together with the amount of water contained in the aqueous slurry of the composite aggregated particle material. When the amount is 0.4 mol/L or more, sufficient aggregation can be achieved, and when the amount is 0.7 mol/L or less, residual surplus ions can be suppressed, which is preferable. If the addition amount is within this range, it is possible to obtain a composite particle material with a high specific surface area, for unknown reasons. Further, a highly hydrophobic organic solvent having a small dielectric constant can be added.

・Granulation process In the granulation process, an alcohol slurry is prepared by replacing the main component of the dispersion medium contained in the aggregates dispersed in the liquid obtained in the aggregation process with alcohol, and the alcohol slurry is granulated by a spray drying method. It is a step of making granules by pressing. The composite particle material of the present embodiment is obtained by directly or drying the granules. In this step, the droplets are instantly dried by a spray drying method, so that spherical granules having a porous structure can be obtained.

The method of replacing the main component of the dispersion medium contained in the aggregates dispersed in the liquid with alcohol is not particularly limited. For example, the alcohol content can be improved by simply adding alcohol, or the alcohol content can be improved by repeatedly removing the dispersion medium after adding the alcohol. The dispersion medium can be removed by separating the dispersion medium separated by centrifugation as a supernatant or by evaporating the dispersion medium.

Here, "alcohol is the main component" means that the content of alcohol is 50% or more based on the entire dispersion medium. %, preferably 99% by volume.

In addition, the alcohol that can be contained in the alcohol slurry is not particularly limited, but it is preferable to select an alcohol solvent that evaporates at a low temperature in order to further suppress the surface oxidation of the MXene nanosheets. For example, at least one of methanol, ethanol, and isopropanol is preferably used as the alcohol used as the dispersion medium. Besides alcohol, it may contain water, ketones such as MEK, or DMSO. The lower limit of the content of alcohol includes 99%, 95%, and 90% based on the volume of the dispersion medium.

The spray-drying method is performed in an inert atmosphere, which has low reactivity with each material that makes up the composite particle material. As the inert atmosphere, an atmosphere filled with an inert gas such as nitrogen or argon, or a reduced pressure or vacuum atmosphere can be used. The temperature of the inert atmosphere is the temperature at which the alcohol contained in the alcohol slurry can evaporate. For example, 80°C, 90°C, and 100°C can be adopted as the lower limit values of the temperature of the inert atmosphere, and 100°C, 110°C, and 120°C can be adopted as the upper limit values. The upper limit and lower limit can be arbitrarily combined.

The spray-drying method is performed by spraying droplets of a slurry of composite agglomerated material into a high-temperature atmosphere. Usual methods such as a method of using a rotating disk and a method of using a nozzle such as a two-fluid nozzle can be employed as the method of spraying. A method using a rotating disk is preferable in that the agglomerated particles in the alcohol slurry are unlikely to clog during spraying and that spherical granules having an arbitrary secondary particle size can be produced. Spherical granules having a required secondary particle size can be easily obtained by selecting the rotational speed of the rotating disk. In addition to or instead of the spray drying method, a step of granulating by a fluidized bed granulation method can be included.

Since the dispersion medium is instantaneously removed from the droplets composed of the sprayed composite agglomerated particle material and alcohol, the composite particle material is formed, resulting in a high specific surface area without shrinkage and excellent interdispersion of MXene nanosheets and carbon microparticles. to maintain Since the particle size of the aggregated particles in the alcohol slurry is large, clogging is likely to occur during spraying or liquid feeding. Therefore, it is necessary to appropriately select the solid content concentration, which is preferably 1.0 to 10.0% by mass. More preferably 1.0 to 5.0% by mass. As for the secondary particle size, when the rotating disk method is used, a large secondary particle size can be obtained by lowering the number of revolutions and increasing the spray temperature. On the other hand, a small secondary particle size can be obtained by increasing the rotational speed. Furthermore, a smaller secondary particle size can be obtained by reducing the aggregate particle size of the alcohol slurry of the composite aggregated particle material and spray-drying it using a nozzle such as a two-fluid nozzle. By combining these, an average secondary particle size of 1.0 μm to 15.0 μm can be obtained. 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 from which large agglomerated particles have been removed through a sieve in order to prevent clogging of the nozzle. Practically, when the average secondary particle size is 1.0 μm or more, the composite particle material is less likely to scatter during work, which is preferable. In order to obtain a composite particle material when it is 15.0 μm or less, it is necessary to use an alcohol slurry with a high particle concentration to increase the size of the droplets at low speed rotation, or to form without instantaneously removing the alcohol at a high temperature. becomes possible. In particular, it is preferable because the problem of surface oxidation of MXene is less likely to occur because high-temperature treatment can be avoided. When used as a battery material, the average secondary particle size is preferably 1.0 μm to 15.0 μm. 1.0 μm to 11.0 μm is more preferable. This is because when the thickness is 1.0 μm or more, handling becomes easy, and when the thickness is 15.0 μm or less, formation of irregularities in the film to be produced is suppressed. In particular, around 11.0 μm (10.5 μm to 11.5 μm) is more preferable.

Drying step The granules obtained in the granulation step can be used as the composite particle material of the present embodiment as they are, but can be dried after that for the purpose of removing inter-layer water of the MXene nanosheets. The drying step is a step of drying the granules at 100 to 120° C. under a vacuum atmosphere or an inert atmosphere to obtain the composite particle material of the present embodiment. Here, the vacuum atmosphere and the inert atmosphere are atmospheres employed to suppress oxidation of the MXene nanosheets, and any atmosphere that can suppress oxidation compared to air is sufficient.

By suppressing the remaining inter-layer water of MXene nanosheets, it is possible to suppress the deterioration of characteristics when the number of cycles is increased when used as electrodes for secondary batteries and pseudocapacitors. The temperature of the drying process is determined by the temperature of the granules. In order to control the temperature of the granules, the temperature of the atmosphere is controlled, the granules are directly heated by infrared rays, etc., the temperature of the container containing the granules is controlled, and the granules are heated by heat transfer. You can control the temperature.

The temperature at which the drying process is performed is a temperature at which the MXene nanosheets are not denatured or within an allowable range of denaturation, and a temperature at which moisture contained between the layers of the MXene nanosheets can be removed. Interlayer water can be effectively removed by performing the drying process. For example, a water content of less than 10% by weight, based on the total weight, can easily be reached. The time for performing the drying process is not particularly limited, but it is preferable to perform 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. . More preferably, the water content is 8% or less, 6% or less, 4% or less, 2% or less, or 1% or less, and the mass change is more preferably 0.5% or less per hour. .

-Other necessary steps Other necessary steps are not particularly limited, but a pretreatment step can be exemplified. The pretreatment step is an example of a method for manufacturing MXene. For example, a mixed raw material of TiC, TiN, Al, and Ti is pressurized in the range of 1 ton/cm ² to 3 ton/cm ² by CIP or uniaxial pressure, or pressurized. Ti ₃ Al _a (C( _1.0 _-x )N _x ) ₂ , (0 ≤ x≦0.25 and a is 1.0). Alternatively, it can be produced by contacting the MAX phase ceramic powder with an acidic substance at a temperature controlled at 20° C. to 30° C. to remove part of the Al element contained in the MAX phase ceramic powder.

The raw material to be subjected to the pretreatment step is represented by _Ti3Ala (C( _1.0 _-x ) _Nx ) ₂ , (0≤x≤0.25, a is 1.0 ₎ for the Ti3 layer. It is a MAX phase ceramic powder having a composition. Further, the amount of Al to be removed is adjusted so that the amount of Al (corresponding to x) in the MAX phase ceramic powder produced by acid treatment with an acidic substance remains at least 0.01. 0.02 can be adopted as the lower limit. More preferably, the upper limit is adjusted to 0.05. In addition, it is possible to remove all the Al, and in that case, it is preferable not to proceed the acid treatment beyond the removal of the Al.

The amount of Al to be removed depends on the contact time with the acidic substance (acid aqueous solution, etc.) (the longer the time, the more removed), the concentration of the acidic substance (the higher the concentration, the more removed), It can be adjusted by changing 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).

A multi-layer with a size of several micrometers having a void layer that constitutes a particle material by removing part of Al by acid-treating MAX phase ceramic powder (A element is Al), which is a layered compound. A layered compound. As the acid for removing part of the Al layer, an acidic substance in which hydrofluoric acid and hydrochloric acid are combined is employed. In order to achieve a combination of hydrofluoric acid and hydrochloric acid, it is preferable to mix a hydrofluoric acid salt (KF, LiF, etc.) with hydrochloric acid to obtain a mixture of hydrofluoric acid and hydrochloric acid.

In particular, aqueous solutions of these acids are used as acidic substances. The mixed concentration of hydrofluoric acid and hydrochloric acid formed when the fluoride salt is completely dissociated is not particularly limited. As for the concentration of hydrofluoric acid, the lower limit is about 1.7 mol/L, 2.0 mol/L, and 2.3 mol/L, and the upper limit is about 2.5 mol/L, 2.6 mol/L, and 2.7 mol/L. can. The concentration of hydrochloric acid can be about 2.0 mol/L, 3.0 mol/L and 4.0 mol/L with lower limits and about 13.0 mol/L, 14.0 mol/L and 15.0 mol/L with upper limits. .

The mixing ratio (molar ratio) of hydrofluoric acid and hydrochloric acid formed when it is assumed that the fluoride salt is completely dissociated is not particularly limited, but the lower limit of hydrofluoric acid is 1:13, 1:12, 1:1: 11. About 1:5, 1:6 and 1:7 can be adopted as the upper limit. The concentrations and mixing ratios of hydrofluoric acid and hydrochloric acid shown here can be used in arbitrary combinations. The acid treatment temperature is preferably 20°C to 30°C. 20°C to 25°C is more preferred.

(Electrode material)
The electrode material of the present embodiment is a material that can be suitably used for secondary batteries. In particular, since Li ions and Na ions can be intercalated and detached between layers, it can be suitably used as an electrode active material. Moreover, it can also be used as a conductive aid because of its conductivity. Effective for lithium secondary batteries and sodium secondary batteries. Lithium ions and sodium ions are stored and desorbed in the void layer from which the Al layer has been removed by acid treatment.

Here, we will use a lithium secondary battery as an example. The electrode has an active material layer containing an active material made of the composite particle material of the present embodiment, and a current collector made of a thin metal plate or the like and having an active material layer made of the active material formed on the surface thereof. A binder may be included to form the active material layer. Moreover, the active material layer can contain an active material other than the composite particle material of the present embodiment, a conductive auxiliary agent, and the like, if necessary. As the binder, a commonly used binder such as carboxymethyl cellulose, polyvinylidene fluoride, styrene-butadiene rubber, polyvinylpyrrolidone, polyvinyl alcohol, or any other binder that can be used can be used. Acetylene black, ketschen black, carbon nanotube, graphene, carbon fiber, graphite powder, hard carbon powder and the like can be used as the conductive auxiliary agent.

The composite particle material of the present invention and its manufacturing method will be described in detail below based on examples.

(Example 1)
・Pretreatment process TiC powder (TI-30-10-0020, Rare Metallic) 12.3 g, Ti powder (TIE07PB 3N, Kojundo Chemical) 4.9 g, Al powder (ALE15PB 3NG, Kojundo Chemical) 2.8 g was ball-mill mixed in isopropanol (IPA) for 12 hours, and the IPA was removed by an evaporator to obtain a uniformly mixed dry powder.

Using a graphite resistance furnace, the uniformly mixed dry powder was placed in an alumina crucible and sintered in an Ar stream at 1450° C. for 2 hours to obtain Ti ₃ AlC ₂ as MAX phase ceramics. The resulting Ti ₃ AlC ₂ was coarsely pulverized using a mortar and pestle, and then subjected to ball mill pulverization using 5 mm zirconia balls in IPA for 24 hours. Then, planetary ball mill pulverization (200 rpm, 15 minutes three times) using 0.5 mm zirconia balls was performed to obtain a suspension. IPA was removed from the suspension with an evaporator to obtain Ti ₃ AlC ₂ powder pulverized to about 3 μm.

Prepare an acid aqueous solution by adding 18 g of LiF to 300 mL of concentrated HCl, add 10 g of Ti ₃ AlC ₂ powder while cooling with ice, and stir with a magnetic stirrer for 24 hours under an environment controlled at 10 to 20 ° C. By stirring, the Al was etched away to obtain a particulate material consisting of Ti ₃ Al _0.02 C ₂ MXene. After etching, it was washed with water until the pH reached about 6, and finally water was replaced with ethanol. This operation resulted in a raw suspension of the particulate material suspended in ethanol.

The raw material suspension was adjusted by measuring the particle concentration and adding water so that the particle concentration of Ti ₃ Al _0.02 C ₂ MXene was 15.6 mg/mL.

・Exfoliation process Ti ₃ Al _0.02 C ₂ was processed by treating this raw material suspension in a bead mill with a ZrO ₂ bead diameter of 50 μm under the conditions of a slurry feed rate of 150 mL/min and a ZrO ₂ bead filling amount of 80%. An exfoliate consisting of MXene was produced. By repeating this treatment three times, almost all of the particle material composed of Ti ₃ Al _0.02 C ₂ MXene contained in the raw material suspension (99% or more on a mass basis) becomes exfoliated substances, including the exfoliated substances. A flake suspension was obtained.

The resulting exfoliated material suspension was dropped onto a piranha-treated Si substrate (immersed in a mixed solution of H ₂ SO ₄ :H ₂ O ₂ =3 parts by volume:1 part by volume) and subjected to AFM analysis. An AFM image is shown in FIG. 100 exfoliated exfoliated products (nanosheets) were randomly sampled, and the average value of the thickness measured by AFM was obtained and shown in Table 1. Furthermore, the result of SEM observation is shown in FIG. 100 exfoliated products were randomly selected, and the vertical (maximum diameter in the direction perpendicular to the thickness direction) and horizontal (direction perpendicular to the vertical and thickness directions) dimensions were measured from the SEM photograph, and the average value was calculated. Table 1 shows the average value of the size of 100 exfoliated objects. A powder of Ti ₃ AlC ₂ , which is a MAX phase ceramic, was subjected to XRD measurement, and its profile is shown in FIG. The peeled substance was measured for zeta potential in water at pH 7.0 and found to be -28.9 mV.

・Acid treatment process As a method for acid treatment of acetylene black as fine carbon particles, 100 parts by mass of a mixed acid in which sulfuric acid (98% by mass) and nitric acid (68% by mass) are mixed at a volume ratio of 3:1 is mixed with 1 part of acetylene black. 0 mass part was added, and the mixture was immersed for 10 minutes in an environment of 85°C. Then, it was washed with water until the pH reached about 6.0, and then the water was replaced with IPA. It was air-dried at room temperature to obtain a hydrophilic acid-treated acetylene black powder. FTIR analysis detected a COOH group and a CO group as surface functional groups. The measured zeta potential at pH 7.0 in water was -22.5 mV. The acid-treated acetylene black was deagglomerated with a shaker under conditions of 140 rpm, amplitude of 45 mm, and 24 hours to prepare a hydrophilic acetylene black aqueous slurry. A hydrophilic acetylene black aqueous slurry was dropped onto a hydrophilized Si wafer and observed with an SEM. 100 primary particles were arbitrarily observed, the vertical and horizontal dimensions were measured, and the average primary particle diameter is shown in Table 1.

Mixing step and aggregation step To 220 mL of the exfoliated material suspension having a particle concentration of 15.6 mg/mL obtained in the exfoliating step, 5.3 g of lithium chloride powder and acetylene black powder acid-treated in the acid treatment step are added to the exfoliated material. After adding 0.172 g, which is 5% by mass based on (Ti ₃ Al _0.02 C ₂ MXene), the mixture was uniformly stirred for 5 hours with a shaker at 140 rpm and an amplitude of 45 mm. Acetylene black was added as a dispersion slurry in 10 mL of water as described above. After uniform stirring, an aqueous solution prepared by dissolving 3.5 g of lithium hydroxide in 30 mL of pure water was completely dissolved with a shaker at 140 rpm for 1 hour and an amplitude of 45 mm. and an amplitude of 45 mm for 1 hour. After that, wash with water once, replace with ethanol three times, stir with a shaker for 6 hours under conditions of 140 rpm in ethanol to loosen coarse aggregates, and obtain a particle concentration of 5.0 mg / mL. An ethanol slurry of aggregates was obtained. Water washing and ethanol replacement were carried out by adding water or ethanol, centrifuging at 1000 to 8000 G for 10 minutes to sediment aggregates, and removing the supernatant. The content of ethanol as alcohol in the resulting alcohol slurry was 99% based on the mass of the entire dispersion medium.

- Granulation process Using a spray dryer, an alcohol slurry of the composite aggregated particle material was spray-dried to prepare granules. The operating conditions were a disk rotation speed of 20,000 rpm, a nitrogen atmosphere, an alcohol slurry injection temperature of 80° C., and an alcohol slurry injection rate of 1.4 kg/hour.

・ Drying process The granules obtained in the granulation process are dried in a vacuum at 110 ° C. for 6 hours to remove the water between the layers, and the MXene / conductive carbon black composite particle material of the present example is dried. got

- Evaluation The SEM photograph (Fig. 4) of the obtained composite powder is shown. As is clear from the figure, the resulting composite particle material has a high degree of sphericity, and when enlarged, maintains a 3D porous aggregation structure with extremely thin MXene nanosheets in which acetylene black is uniformly dispersed, and has a high specific surface area. I found out. When 100 secondary particles were similarly observed with an SEM, they were all composite particle materials having the same porous microstructure. In other words, it became clear that the microstructure was not disturbed by external stress.

Table 2 shows the average secondary particle diameter and sphericity of the secondary particles, and Table 3 shows the specific surface area, average pore diameter, average pore volume and bulk density. FIG. 5 shows nitrogen adsorption isotherms. For the average diameter of the secondary particles, 100 particles were arbitrarily extracted from the SEM image, and the secondary particle diameter was calculated as (long side + short side)/2, and the average was calculated as the average diameter. For the sphericity of the secondary particles, 100 particles were sampled and the short side/long side were measured, and the average was calculated as the sphericity. The upper limit is 1.0, and the closer to 1.0, the higher the sphericity. The bulk density of secondary particles was measured according to JIS1628-1997. The specific surface area, average pore diameter, and average pore volume were measured by the BET method immediately after heating at 110°C for 6 hours in vacuum. The degree of interdispersion, which is the degree of dispersion of the primary particles of each of the Ti ₃ Al _0.02 C ₂ MXene nanosheets and acetylene black as fine carbon particles, was measured. Specifically, it was quantified by Raman spectroscopic analysis. 100 points were analyzed in the laser intensity range from 100 cm ⁻¹ to 2000 cm ⁻¹ at a laser intensity at which anatase does not precipitate, and the standard deviation of the B peak intensity/A peak intensity ratio was calculated as the interdispersion degree. Table 4 shows the interdispersion index obtained. The obtained composite particle material was heat-treated in vacuum at 110° C. for 5 hours, and the change in mass was measured. Furthermore, the obtained composite particle material was subjected to XRD measurement, and the profile is shown in FIG. Table 6 shows the interlayer distance of the (002) plane of MXene nanosheets from the results of XRD measurement. The resulting composite particle material was uniaxially pressed in a φ10 mm mold at a pressure of 0.5 kg/cm ² and then subjected to cold isostatic pressing (CIP) at a pressure of 1.0 ton/cm ² . Table 7 shows the electrical resistance of the surface of the powder measured by the four-probe method using a copper wire of φ0.1 mm.

(Example 2)
Using a graphite resistance furnace, the uniformly mixed dry powder was placed in an alumina crucible and fired under the conditions of 1430° C. for 2 hours in an Ar stream to obtain Ti ₃ AlC ₂ as MAX phase ceramics. to obtain a composite particle material. Measurements were taken in the same manner as in Example 1, and the results are shown in the figure and table. An AFM image of the exfoliated MXene nanosheet is shown in FIG. 6, and an SEM image is shown in FIG. FIG. 8 shows the XRD profile of the MAX phase ceramics and the composite particle material, and FIG. 9 shows the 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 particle material, and Table 2 shows the specific surface area, average pore diameter, average pore volume, and bulk density. Table 4 shows the degree of interdispersion, Table 5 shows the change in mass, Table 6 shows the interlayer distance of the (002) plane of MXene nanosheets, and Table 7 shows the surface electrical resistance.

(Example 3)
A composite particle material of MXene and acid-treated acetylene black was produced in the same manner as in Example 2, except that the amount of acid-treated acetylene black added was 10% by mass based on the mass of Ti ₃ Al _0.02 C ₂ MXene nanosheets. Table 2 shows the average particle diameter and sphericity of the obtained composite particle material, which were 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 degree of dispersion, Table 5 shows the change in mass, Table 6 shows the interlayer distance of the (002) plane of MXene nanosheets, and Table 7 shows the surface electrical resistance.

(Example 4)
A composite particle material of MXene and acid-treated acetylene black was produced in the same manner as in Example 2, except that the amount of acid-treated acetylene black added was 3% by mass based on the mass of the Ti ₃ Al _0.02 C ₂ MXene nanosheets. Table 2 shows the average particle diameter and sphericity of the obtained composite particle material, which were 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 degree of dispersion, Table 5 shows the change in mass, Table 6 shows the interlayer distance of the (002) plane of the MXene nanosheet, and Table 7 shows the surface electrical resistance.

(Example 5)
TiC powder (TI-30-10-0020, Rare Metallic) 9.2 g, TiN powder (TN-30-10-0020, Rare Metallic) 3.2 g, Ti powder (TIE07PB 3N, Kojundo Chemical)4. Ti ₃ Al(C _0.75 N _0.25 ) ₂ powder was prepared in the same manner as in Example 1 using 9 g of Al powder (ALE15PB 3NG, Kojundo Chemical) and 2.8 g of Al powder (ALE15PB 3NG, Kojundo Chemical) as starting materials. It was confirmed by XRD analysis that the powder was MAX phase ceramic powder free of impurities. Using this, a composite particle material was prepared in the same manner as in Example 1. Table 2 shows the average particle diameter and sphericity of the obtained composite particle material, which were 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 degree of dispersion, Table 5 shows the change in mass, and Table 6 shows the interlayer distance of the (002) plane of the MXene nanosheets.

(Comparative example 1)
A composite particle material of MXene and acid-treated acetylene black was produced in the same manner as in Example 2, except that the amount of acid-treated acetylene black added was 2% by mass based on the mass of Ti ₃ Al _0.02 C ₂ MXene nanosheets. Table 2 shows the average particle diameter and sphericity of the obtained composite particle material, which were 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 degree of dispersion, Table 5 shows the change in mass, and Table 6 shows the interlayer distance of the (002) plane of the MXene nanosheets.

(Comparative example 2)
An ethanol slurry of the composite aggregated particle material was prepared in the same manner as in Example 2 up to the mixing step and the aggregation step. In order to further reduce the amount of water remaining in the solvent, ethanol was replaced with IPA to prepare an IPA slurry of the composite aggregated particle material. The IPA slurry was subjected to centrifugal sedimentation (7900 G), and the sediment was air-dried for 12 hours at room temperature. After that, heat treatment was performed at 60° C. for 6 hours in vacuum to obtain a mass of composite agglomerated particle material. After that, it was pulverized by applying physical stress with a grinder composed of a mortar and a pestle to produce the composite particulate material of this comparative example. The same operations as in Example 1 were performed for other steps.

Measured 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 are shown in Table 3, and the degree of interdispersion are shown 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 with an SEM to examine the uniformity of the fine structure when pulverized by applying physical stress. Most of the secondary particles maintained the aggregation structure, but the aggregation structure was destroyed in some secondary particles (Fig. 10).

(Comparative Example 3)
A stripped material suspension was obtained in the same manner as in Example 1 up to the stripping step. An aqueous solution of 3.5 g of lithium hydroxide dissolved in 40 mL of pure water was added to 220 mL of the exfoliated material suspension having a particle concentration of 15.6 mg/mL obtained in the exfoliation step in advance for 1 hour with a shaker at 140 rpm and an amplitude of 45 mm. A completely dissolved alkaline aqueous solution was added under the conditions and stirred for 1 hour with a shaker at 140 rpm and an amplitude of 45 mm. After that, wash with water once, replace with ethanol three times, stir with a shaker for 6 hours under conditions of 140 rpm in ethanol to loosen coarse aggregates, and obtain a particle concentration of 5.0 mg / mL. An ethanol slurry of aggregates was obtained. As in Comparative Example 2, the solvent was replaced with IPA to prepare an IPA slurry of the composite aggregated particle material. The IPA slurry was centrifuged (7900 G) to settle the composite agglomerated particulate material and the sediment was air dried for 12 hours at room temperature. Then, it was dried in vacuum at 60° C. for 6 hours to obtain a mass of composite agglomerated particle material. After that, it was pulverized by applying physical stress with a grinder composed of a mortar and pestle to prepare a composite particulate material. A paste was prepared by adding 5% acid-treated acetylene black and N-methylpyrrolidone (NMP) to the prepared secondary particles based on the mass of MXene. Paste preparation was performed with a grinder consisting of a mortar and pestle. After that, it was dried in vacuum at 110° C. for 6 hours to remove NMP, thereby producing a composite particle material of MXene and acetylene black. The same operations as in Comparative Example 2 were performed for other steps.

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 are shown in Table 3, and the interdispersion degree is shown in Table 3. Table 4 shows the change in mass, and Table 6 shows the interlayer distance of the (002) plane.

(Comparative Example 4)
220 mL of exfoliated material suspension was obtained in the same manner as in Example 1 up to the exfoliation step. 220 mL of IPA was added to create an MXene aggregate particle slurry in a mixed solution of IPA and water. This was centrifuged (7900 G) and the sediment was air-dried at room temperature for 12 hours. After that, it was dried in vacuum at 60° C. for 6 hours to obtain an aggregate mass. After that, a crusher composed of a mortar and a pestle was used to apply physical stress to crush the powder to produce secondary particles. A paste was prepared by adding N-methylpyrrolidone (NMP) dispersed with 5% acid-treated acetylene black based on the mass of MXene to the prepared secondary particles. The paste was made using a grinder consisting of a mortar and pestle. Thereafter, NMP was removed at 110° C. for 6 hours in vacuum to produce a composite particle material of MXene and acetylene black. The same operations as in Comparative Example 3 were performed for other steps.

The average particle diameter and sphericity of the obtained composite particle material were measured in the same manner as in Example 1. Table 2 shows the specific surface area, average pore diameter, average pore volume, and bulk density. The lines are shown in FIG.

A specific description will be given with reference to tables and figures. From Table 4, the composition of Ti ₃ Al _0.02 C ₂ MXene (97.0-90.0% by mass)/carbon particles (3.0-10.0% by mass) and Ti ₃ Al _0.02 (C _0.75 N _0.25 ) ₂ A composite powder material spray-dried with an agglomerated powder alcohol slurry having a composition of MXene (95% by mass)/carbon particles (5.0% by mass) is dried without shrinkage in order to remove the alcohol instantaneously. As a result, the interdispersion degree was remarkably excellent. Conductive carbon microparticles are uniformly arranged on the outer surface of the MXene nanosheet, making it possible to smoothly transfer electrons to the current collector.

From Table 2, FIGS. 4 and 9, the composition of Ti ₃ Al _0.02 C ₂ MXene (97.0-90.0% by mass)/carbon particles (3.0-10.0% by mass) and Ti ₃ Al _0.02 ( C _0.75 N _0.25 ) ₂ MXene (95% by mass)/carbon microparticles (5.0% by mass) The composite powder material spray-dried from an alcohol slurry of agglomerated powder has a spherical shape with an average secondary particle size of approximately single micrometer. Excellent degree. High-magnification SEM observation of 100 secondary particles showed the 3D porous structure shown in FIGS. 4 and 9 as representative examples. On the other hand, when a lump of agglomerated powder is air-dried and vacuum-dried at 60° C. and then pulverized by applying physical stress using a mortar and pestle (grinder), as can be seen from the SEM image in FIG. The pulverized portion and the unpulverized coarse portion are mixed, and the shape becomes irregular. This makes it impossible to obtain a uniform film when manufacturing a cell film. Furthermore, 100 composite powder materials were observed with a high-magnification SEM to investigate whether the aggregated structure was destroyed by the application of physical stress. As shown in FIG. 10 as a representative example, it was confirmed that the aggregation structure was broken for several pieces. When physical stress was applied for a long time to reduce the secondary particle size, the aggregate structure was further destroyed.

Table 3 shows the physical values of the 3D porous structure. Composition of Ti ₃ Al _0.02 C ₂ MXene (97.0-90.0% by mass)/carbon particles (3.0-10.0% by mass) and Ti ₃ Al _0.02 (C _0.75 N _0.25 ) ₂ MXene (95% by mass %)/carbon microparticles (5.0% by mass) The composite powder material obtained by spray-drying the agglomerated powder alcohol slurry has a higher specific surface area than the composite particle material obtained by pulverizing the agglomerates by applying physical stress. Average pore diameter and average pore volume increase. This is because the droplets of the agglomerated powder alcohol slurry are dried instantly, so shrinkage during drying is suppressed. As shown in Table 1, MXene is peeled off to a monolayer level, specifically a thickness of 1.5 nm. Shrinkage during drying means that the MXene nanosheets adhere to each other, and obtaining a composite powder material without shrinkage indicates that the composite powder material is produced while maintaining the MXene nanosheets at the monolayer level. Smooth ion diffusion leads to rapid charging and discharging, excellent cycle characteristics, and high capacity.

We will specifically explain the effect of the average size of MXene nanosheets on the physical values of the 3D porous structure of the composite particle material after granulation. When Example 1 and Example 2 are compared, Example 2 has a larger specific surface area. When the sintering (synthesis) temperature of MAX phase ceramics is lowered within a range that does not produce impurities, the bonding force between the layers decreases, and the average size decreases while maintaining the thickness at the monolayer level in the exfoliation process. A smaller average size of about 0.2 μm (Example 2) had a larger specific surface area, a smaller average pore diameter, and a larger pore volume than about 0.8 μm (Example 1).

The adsorption isotherms of Examples 1, 2 and Comparative Example 4 are shown in FIG. 5 as typical examples. It can be seen that the composite particulate material of the present invention is an excellent 3D porous material.

Table 5 shows the change in mass when 0.3 g of the composite powder material was evenly spread on a dish of 20 cm ³ or more and heated in vacuum at 110° C. for 5 hours. Ti ₃ Al _0.02 C ₂ MXene (97.0-90.0% by mass)/carbon particles (3.0-10.0% by mass) composition, and Ti ₃ Al _0.02 (C _0.75 N _0.25 ) ₂ MXene (95 mass %)/carbon fine particles (5.0 mass %) / carbon fine particles (5.0 mass %) The composite powder material is prepared by spray-drying the agglomerated powder alcohol slurry. Residual water is completely removed. On the other hand, a large amount of water remained between the MXene layers in the composite particle material obtained by pulverizing the aggregates air-dried and then vacuum-dried at 60° C. by applying physical stress. When the agglomerate is air-dried and then vacuum-dried at 110° C., it shrinks significantly, resulting in a low specific surface area. Although the film is usually vacuum-dried at 110° C. after forming the film in cell production, it is difficult to completely remove the water between the layers of MXene, resulting in problems such as deterioration in cycle characteristics.

Table 3 shows the bulk density of the obtained composite particle material. Ti ₃ Al _0.02 C ₂ MXene (97.0 to 90.0% by mass)/carbon particles (3.0 to 10.0% by mass) composition, and Ti ₃ Al _0.02 (C _0.75 N _0.25 ) ₂ MXene (95 A composite powder material obtained by spray-drying an alcohol slurry of agglomerated powder having a composition of (% by mass)/carbon particles (5.0% by mass) was compared with a composite particulate material obtained by pulverizing agglomerates by applying physical stress. The former has a 3D porous aggregate structure, has a uniform secondary particle size, and is characterized by having a spherical shape. However, there is a feature of continuous particle blending. For this reason, the former has a smaller bulk density.

However, when producing cells such as secondary batteries, the former makes it possible to improve the performance of the produced secondary batteries, etc., because the produced membrane has a uniform structure. In order to produce a high-density membrane, composite particle materials having several types of secondary particle diameters are prepared so that they are properly packed, and a distribution rule that creates the closest packing using the Andreasen equation has been proposed. It is preferable to perform particle blending, or to perform two-stage particle blending in which two types of composite particle materials, coarse particles and fine particles, are blended.

Table 6 shows the interlayer distance of the (002) plane of MXene obtained by XRD of the obtained composite particle material. The composite particle material of the present invention in which the carbon particles are uniformly arranged has a larger interlayer distance than the process in which the carbon particles are mixed by adding NMP after producing the aggregated powder using only MXene. This is because Li and/or Na ions and chloride ions are intercalated between the layers of MXene in the process of uniformly arranging the carbon particles, and the layers are expanded. The numerical value obtained by subtracting the interlayer distance of the (002) plane of MAX phase ceramics from the (002) plane of MXene can be considered as the distance of the gap generated after removing the Al phase of MAX phase ceramics (see FIG. 11). The composite particle material of the present invention will be about 0.6 nm. For example, ions larger than Li ions, such as Na ions, can also be intercalated and deintercalated. Furthermore, since the gap is large, there are advantages such as rapid charge/discharge and long life.

Table 7 shows the surface electrical resistance of the compact. This was done to define the oxidation state of the MXene nanosheet surface and the amount of water remaining between the layers. Oxidation of the surface of MXene nanosheets increases electrical resistance. In addition, if there is water remaining between the layers, it will change over time, oxidizing the surfaces of the layers and increasing the surface electrical resistance. Therefore, if the oxidation progresses or if the amount of moisture between the layers is large, the electrical resistance of the surface increases.

The surface electrical resistance of the compact also affects the number of contacts between powders. The number of contacts is indicated by the relative density of the compact. Relative density is determined by (bulk specific gravity/true specific gravity) x 100. As shown in Table 7, the composite particle material used for the negative electrode active material of the secondary battery and the electrode of the electrochemical capacitor preferably has a surface electrical resistance of 1.0 to 100.0 Ω/□.

As described above, it was found that MXene and microparticles were highly dispersed, maintained an aggregated structure, and produced a composite particle material with a high degree of sphericity. As clarified in PCT/JP2021/018296 previously filed by the present applicant, the original composite particle material is an ideal two-component material that has excellent ion diffusibility and allows electrons to move smoothly to the current collector. Since it is a composite particle material suitable for the negative electrode active material of the secondary battery (storage battery) or suitable for the positive electrode and / or negative electrode active material of the ideal pseudocapacitor, the 3D porous aggregation structure can be maintained, so that the ion diffusion is further improved. It is expected that the degree of sphericity will be increased, and since the degree of sphericity can be increased, it is expected that the uniformity of the film will be improved.

Furthermore, when a composite particle material was produced using methanol or isopropanol instead of ethanol in Example 1, a composite particle material similar to that of Example 1 was obtained. Here, when the composite particulate material was produced using isopropanol instead of ethanol in Example 1, it was necessary to raise the spray temperature in the granulation process to 85°C. As a result of measuring the surface electric resistance in the same manner as in Example 1, it was 60.5 Ω/□, and when ethanol was used, it was 41.1 Ω/□, but the resistance increased slightly. This is because the surface was slightly oxidized because the spray temperature was raised slightly. When the composite particulate material was produced using methanol instead of ethanol in Example 1, the spray temperature in the granulation process could be lowered to 75°C. As a result of measuring the surface electric resistance in the same manner as in Example 1, it was 40.7 Ω/□, which was almost the same as when ethanol was used. For these reasons, the solvent used in the granulation step may be ethanol, methanol, or isopropyl alcohol.

Claims

3 to 10 parts by mass of conductive microparticles and Ti 3 Al a (C( 1.0 -x )N x ) 2 (0≦x≦0.25, a is 0.01 or more) MXene nanosheets 90 to 97 parts by mass as primary particles,
The MXene nanosheet has an average thickness of 1.0 to 3.5 nm,
A composite particle material having the following interdispersion degree 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.
(interdispersion degree)
Calculate 100 ratios (B/A) of peak height A at 400 cm −1 and peak height B at 1332 cm −1 in Raman spectroscopic analysis using a laser with a wavelength of 532 nm, and the 100 B/A values The standard deviation calculated from is taken as the degree of interdispersion.
The composite particle material according to claim 1, wherein the microscopic bodies are carbon microscopic bodies.
3. The composite particle material according to claim 1, which has a specific surface area of 75 m 2 /g or more, an average pore diameter of 10.0 to 20.0 nm, and an average pore volume of 0.30 to 0.70 mL/g.
Any one of claims 1 to 3, wherein a mass change is 1.0% by mass or less when 0.3 g of a sample is evenly spread on a dish of 20 cm 2 or more and heated at 110°C for 5 hours in a vacuum. A composite particulate material according to any one of claims 1 to 3.
The composite particulate material according to any one of claims 1 to 4, which has a bulk density of 0.1 to 0.5 g/cm 3 .
The Ti 3 Al a (C( 1.0 -x )N x ) 2 , (0≦x≦0.25, a is 0.01 or more), and the average size in the spreading direction of the MXene nanosheet is 0.1 to 2.0 μm,
The composite particle material according to any one of claims 1 to 5, wherein the fine particles have a primary particle diameter of 30 to 50 nm.
In the crystal structure of the Ti3Ala (C( 1.0 -x ) Nx ) 2 , (0≤x≤0.25, a is 0.01 or more) MXene, the interlayer distance of the (002) plane is 1 A composite particulate material according to any one of claims 1 to 6, which is between 0.400 nm and 1.700 nm.
Ti 3 Al a (C( 1.0 -x )N x ) 2 with a zeta potential of −25.0 mV to −35.0 mV, (0≦x≦0.25, a is 0.01 or more) MXene and carbon fine particles having a zeta potential of -20.0 mV to -25.0 mV.
(Zeta potential)
The zeta potential is measured in water in the range of pH 6.0 to pH 8.0.
9. The composite particulate material according to any one of claims 1 to 8, wherein the following surface electrical resistance is from 1.0 Ω/square to 100.0 Ω/square.
(Surface electrical resistance)
After heat treatment in vacuum at 110°C for 5 hours, it is uniaxially pressed with a φ10 mm mold at a pressure of 0.5 kg/cm 2 , and then cold isostatically pressed at a pressure of 1.0 ton/cm 2 . The electrical resistance of the surface of the treated green compact measured by the four-probe method using a copper wire of φ0.1 mm is defined as the surface electrical resistance.
A negative electrode for a secondary battery having the composite particle material according to any one of claims 1 to 9 as a negative electrode active material.
An electrode for a pseudocapacitor having the composite particle material according to any one of claims 1 to 9 as the active material of the positive electrode and/or the negative electrode.
Ti3Ala ( C( 1.0 -x ) Nx ) 2 , (0≤x≤0.25, a is 0.01 or more) in a dispersion medium containing 50% by mass or more of water, MXene is peeled off. a stripping step of forming a stripped material by
an acid treatment step of treating raw carbon microparticles in a mixed acid aqueous solution of sulfuric acid and nitric acid at 70° C. or higher for 10 minutes or longer to obtain carbon microparticles;
The particle concentration is 11.5 to 17.0 mg / L, and 0.8 to 1.0 mol / L of A mixing step of adding and stirring a water-soluble lithium salt and/or a water-soluble sodium salt;
An alkaline aqueous solution of 0.4 to 0.7 mol/L is added to the mixture slurry to make the liquid alkaline and aggregate to form the Ti 3 Al a (C( 1.0 -x )N x ) 2 , (0≦x≦0.25, a is 0.01 or more) an aggregation step of obtaining a slurry of aggregates of MXene and the carbon fine particles;
A granulation step of obtaining granules by granulating an alcohol slurry of the aggregates prepared by replacing the dispersion medium of the slurry with alcohol by a spray drying method under an inert atmosphere;
A method for producing a composite particulate material having
The method for producing a composite particulate material according to claim 12, wherein the alcohol is methanol, ethanol and/or isopropanol.
The method for producing a composite particulate material according to claim 12 or 13, comprising a drying step of drying the granules at 100 to 120°C under an inert atmosphere.
In the stripping step, the Ti3Ala (C( 1.0 -x ) Nx ) 2 , (0≤x≤0.25, a is 0.01 or greater) is 99% or more by mass of the stripped material The method for producing a composite particulate material according to any one of claims 12 to 14, wherein the step is performed until