Powder manufacturing apparatus and powder manufacturing method

Abstract

To form a more uniform functional material layer on a powder surface by more efficient treatment.SOLUTION: A powder production apparatus of the present disclosure for coating a functional material on the surface of powder comprises; a supply part that stores a wet powder obtained by wetting powder with a functional material-containing liquid and supplies a fluid containing the wet powder and a heated gas; a first flow part that is connected to the supply part and allows the fluid to flow therethrough; one or more cyclone parts that allow the fluid supplied from the first flow part to stay while flowing it; and a collection part that is connected to the cyclone part and collects the powder contained in the fluid after staying.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure discloses a powder manufacturing apparatus and a powder manufacturing method. [Background technology]

[0002] One proposed electrode material for lithium-ion secondary batteries involves gradually adding a coating solution to an active material and then drying and solidifying the solution on a hot plate to form a coating layer on the surface of the active material (see, for example, Patent Document 1). This electrode material includes an electrolyte material that includes a sulfide layer containing a sulfide material and an oxide formed by oxidizing the sulfide material, and has an oxide layer located on the surface of the sulfide layer, and an active material with a coating layer. It is claimed that further improvements in the charge and discharge efficiency of batteries are desirable. Another proposed electrode material for lithium-ion secondary batteries is one that is produced by forming a slurry from a solution containing a positive electrode active material, lithium, phosphoric acid, and a transition metal, and then drying and heat-treating the slurry to form a lithium-transition metal-phosphate coating layer (see, for example, Patent Document 2). It is claimed that this electrode material can reduce the interfacial resistance between the positive electrode active material and the sulfide-based solid electrolyte. Furthermore, as an electrode material for lithium-ion secondary batteries, for example, a cathode active material whose surface is coated with a glass-based electrolyte by a tumbling flow method in which active material powder is vigorously stirred and thrown up and down in a chamber, and then heated and dried while a coating liquid is sprayed on it has been proposed (see, for example, Patent Document 3). This cathode active material can increase the capacity and charge / discharge efficiency of sulfide all-solid-state batteries. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-32621 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-72772 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-39062 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned Patent Documents 1 and 2, the coating solution sinks due to gravity during static drying, which can cause bias in the concentration of the coating solution and lead to unevenness in the coating layer. Also, in Patent Document 3, a uniform coating layer can be formed by the tumbling flow method, but forming a uniform coating layer requires slow processing over time, and further improvement in processing efficiency has been desired.

[0005] The present disclosure has been made in consideration of such problems, and its main purpose is to provide a powder manufacturing apparatus and a powder manufacturing method that can form a more uniform functional material layer on the powder surface through more efficient processing. [Means for solving the problem]

[0006] After extensive research to achieve the above-mentioned objectives, the inventors discovered that by using a wet powder in which the solid volume fraction is within a predetermined range and the powder is wetted to a degree that does not result in a slurry, and by performing one or more cyclone treatments, a more efficient treatment can be performed and a more uniform functional material layer can be formed on the powder surface, leading to the completion of the invention disclosed in this specification.

[0007] That is, the powder manufacturing apparatus of the present disclosure is A powder manufacturing apparatus for coating a surface of powder with a functional material, a supply unit that stores wet powder obtained by wetting the powder with a liquid containing the functional material and supplies a fluid containing the wet powder and heated gas; a first circulating portion connected to the supply portion and through which the fluid circulates; one or more cyclone sections that cause the fluid supplied from the first circulation section to flow and remain there; a collecting section connected to the cyclone section and configured to collect powder contained in the fluid after the fluid has accumulated; It is equipped with the following.

[0008] The method for producing powder of the present disclosure includes: A method for producing powder in which the surface of the powder is coated with a functional material, comprising the steps of: a supplying step of supplying a fluid containing wet powder obtained by wetting the powder with a liquid containing the functional material and heated gas; one or more cyclone steps in which the supplied fluid is passed through and then retained while flowing; a collecting step of collecting powder contained in the fluid after the cyclone step; It includes: [Effects of the Invention]

[0009] The powder production apparatus and powder production method disclosed herein can form a more uniform functional material layer on the powder surface with more efficient processing. The reasons for this effect are presumed to be as follows: Generally, in static drying, the liquid containing the functional material flows downward due to gravity, resulting in a thicker protective layer and a higher coverage rate for particles at the bottom, potentially resulting in uneven coverage. Furthermore, particles in areas with a higher concentration of the functional material-containing liquid tend to aggregate. On the other hand, in a method of air-flow drying of wet powder using a cyclone, particles are introduced into the airflow while still wet with the liquid and subjected to a disintegrating force due to the centrifugal force generated by the cyclone, resulting in the powder being dried while deagglomerated. In this way, the functional material-coated powder is prevented from agglomerating and has a uniform particle size. Furthermore, the use of one or more such cyclones allows for sufficient drying and disintegration processes, presumably resulting in a more efficient and uniform functional material layer being formed on the powder surface. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram showing an example of a powder manufacturing apparatus 10. [Figure 2] FIG. 1 is a plan view of a powder manufacturing apparatus 10. [Figure 3] 1 is a schematic diagram of a powder manufacturing apparatus 10 when wet powder is introduced. [Figure 4] FIG. 10 is an explanatory diagram showing an example of another powder manufacturing apparatus 10B. [Figure 5] FIG. 1 is an explanatory diagram showing an example of a known tumbling fluidization coating device 110. [Figure 6] Photograph showing the state in which the slurry of Comparative Example 1 adhered to the inside of the device. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Powder manufacturing equipment) The powder manufacturing apparatus of the present disclosure is an apparatus for coating the surface of powder with a functional material. This powder manufacturing apparatus includes a supply unit that stores wet powder obtained by wetting powder with a liquid containing a functional material and supplies a fluid containing the wet powder and heated gas; a first circulation unit connected to the supply unit and circulating the fluid; one or more cyclone units that flow and retain the fluid supplied from the first circulation unit; and a collection unit connected to the cyclone units and collecting the powder contained in the fluid after retention. This powder manufacturing apparatus may include one cyclone unit or two or more. The following will first mainly describe a powder manufacturing apparatus with two cyclone units.

[0012] This embodiment will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of a powder production apparatus 10. FIG. 2 is a plan view of the powder production apparatus 10. FIG. 3 is a schematic diagram of a wet powder being charged into the powder production apparatus 10. The powder production apparatus 10 is an apparatus for coating the surface of powder with a functional material. The powder is not particularly limited, but examples thereof include those used as electrode materials for electricity storage devices. Examples of electrode materials include active material particles, solid electrolyte particles, conductive material particles, binder particles, and current collector particles. Examples of functional materials include protective materials that form protective layers, coating materials that form coating layers, conductive materials that impart conductivity, electrolyte materials that impart ionic conductivity, and binders that impart binding properties.

[0013] For example, the basic composition formula of the active material is Li x Ni a Co b Mn c O2 (where 0≦x≦1.2, 0≦a≦1, 0≦b≦1, 0≦c≦1, a+b+c=1 are satisfied) and Li x Ni a Cob Mn c O4 (where 0 ≦ x ≦ 1.2, 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 < c < 1, and a + b + c = 2), and lithium iron phosphate compounds with a basic composition formula of LiFePO4, etc. Examples of the active material include carbonaceous materials such as cokes, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, and carbon fibers. Examples of the solid electrolyte include LISICON-type oxides, sulfides, perovskite-type oxides, garnet-type oxides, NASICON-type oxides, glass-ceramics, and thiolicon solid electrolytes. Examples of the conductive material include graphite such as natural graphite (scaly graphite, flaky graphite) and artificial graphite, acetylene black, carbon black, ketjen black, carbon whiskers, needle coke, carbon fibers, metals (such as copper, nickel, aluminum, silver, gold, etc.). Examples of the binder include fluorine-containing resins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluororubber, or thermoplastic resins such as polypropylene and polyethylene, ethylene propylene diene monomer (EPDM) rubber, sulfonated EPDM rubber, natural butyl rubber (NBR), etc. Examples of the protective material include LiNbO3, etc. Examples of the liquid for wetting the powder include water and organic solvents, among which water is preferred. Examples of the organic solvent include alcohols, acetone, chloroform, as well as N-methylpyrrolidone (NMP), dimethylformamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethylene triamine, N,N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran, etc. Here, for the sake of convenience of explanation, the powder is the active material particles of the power storage device, the functional material is the protective material of the active material, and the powder manufacturing apparatus 10 for forming a protective layer including the protective material on the surface of the active material particles will be mainly described.

[0014] The powder manufacturing apparatus 10 includes a supply unit 11, a first circulation unit 16, a first cyclone unit 21, a second circulation unit 22, a second cyclone unit 24, a collection unit 25, a suction unit 27, and a control unit 28.

[0015] The supply unit 11 is a unit that stores wet powder obtained by wetting powder with a liquid containing a functional material and supplies a fluid (hereinafter simply referred to as a fluid) containing the wet powder and heated gas. In the powder production apparatus 10, the use of flash drying allows for a short processing time (e.g., less than one second) from powder input to collection. The supply unit 11 includes a storage unit 12, a heating unit 13, and a constant volume feeder. The storage unit 12 is a container for storing wet powder. The storage unit 12 may store and supply wet powder with a solid volume fraction of greater than 40% by volume, for example. In the range of 40% by volume or less, dilatancy occurs or the powder becomes a slurry state, resulting in a loss of particle fluidity, making flash drying unsuitable for this apparatus. On the other hand, there is no particular upper limit on the volume percentage. The wet powder is not a liquid such as a slurry, but rather a powder that contains liquid but has voids and retains powder fluidity. This wet powder may be, for example, a powder in the pendular range. The heating section 13 is a heater that heats the gas flowing through the device. Examples of the gas to be heated include air, nitrogen, and rare gases, and the gas is selected depending on the object to be treated. The constant volume feeder is a device that feeds a fixed amount of wet powder from the storage section 12 to the first flow section 16. The supply section 11 may be one that supplies gas heated to a temperature range of 100°C or higher and 230°C or lower. The supply section 11 may have a capacity of 0.5 m 3 / min or more, preferably 0.8m 3 / min more than 7.5m 3 The gas supply conditions of the supply unit 11 may be appropriately selected depending on the object to be treated.

[0016] The first circulating section 16 is a unit connected to the supply section 11 and the first cyclone section 21 and circulates a fluid. The first circulating section 16 includes a mixing section 17 connected to the supply section 11 and having a larger volume than the first cyclone section 21, and a circulation pipe 18 connecting the mixing section 17 and the first cyclone section 21. The mixing section 17 is a portion where the heated gas and the wet powder supplied from the supply section 11 flow downward and mix, and is a cylinder with a larger diameter than the first cyclone section 21. Note that the first circulating section 16 may not include the mixing section 17 and the supply section 11 may be directly connected to the circulation pipe 18. However, from the viewpoint of further mixing the heated gas and the wet powder and increasing the movement speed, it is preferable to connect the mixing section 17. The mixing section 17 may have a diameter similar to that of the circulation pipe 18. The first circulating section 16 may have a length at least twice the total length L of the first cyclone section 21. Since the first flow section 16 is relatively long, the heated gas and the wet powder can be mixed sufficiently before reaching the first cyclone section 21.

[0017] The first cyclone section 21 is a unit that dries wet particles by causing a fluid to flow and accumulate in a vortex or spiral shape, and also performs a process that breaks down the powder particles by causing them to collide with each other, thereby suppressing particle aggregation. In the first cyclone section 21, the powder is caused to fly while rotating in the cyclone, thereby increasing the flight distance and improving drying efficiency. The first cyclone section 21 has a cylindrical main body with the first flow section 16 disposed at the top, and a tapered section connected to the bottom of the main body, the inner diameter of which decreases downward.

[0018] The second circulating section 22 is a circulating pipe that is connected to the first cyclone section 21 and the second cyclone section 24 and that circulates the fluid that has accumulated in the first cyclone section 21. The second circulating section 22 includes a U-shaped pipe connected to an outlet formed in the lower part of the first cyclone section 21, a vertical pipe that guides the fluid upward, and a horizontal pipe that guides the fluid horizontally. The horizontal pipe is connected perpendicular to the second cyclone section 24. If the second circulating section 22 is relatively long, a longer drying time can be ensured.

[0019] The second cyclone section 24 is a unit connected to the second flow section 22 and performs a process of retaining the fluid while it flows. The upper part of the second cyclone section 24 is connected to the filter 26, and the suction section 27 is connected downstream of the filter 26. A collection section 25 for collecting powder is disposed below the second cyclone section 24. In this second cyclone section 24, the gas flow flows to the downstream filter 26, and the powder falls downward under its own weight. Therefore, the second cyclone section 24 has the function of separating the coated powder from the gas flow with high yield. Similarly to the first cyclone section 21, the second cyclone section 24 also has the function of retaining the fluid while flowing it in a vortex or spiral shape to dry the wet particles, and also has the function of crushing the powder particles by colliding with each other, thereby suppressing particle aggregation. The second cyclone section 24 includes a cylindrical main body with the second flow section 22 disposed at the top, and a tapered section connected to the bottom of the main body and having an inner diameter that decreases downward.

[0020] The collection unit 25 is connected to the second cyclone unit 24 and is a container that collects powder contained in the fluid after it has accumulated in the second cyclone unit 24. The collection unit 25 is removably disposed in the second cyclone unit 24. The filter 26 prevents the powder from being sucked into the suction unit 27, which is disposed downstream of the filter 26. The gas that flows out from the filter 26 enters the suction unit 27, where it is dried by a dehumidifier (not shown), and is sent back to the heating unit 13. The suction unit 27 reduces the pressure within the system to allow the gas to circulate, and may be, for example, a vacuum pump, a suction pump, or an aspirator.

[0021] The control unit 28 is configured as a controller centered on a CPU (not shown) and controls the entire device. The control unit 28 is electrically connected to the supply unit 11 and the like, receives signals from the supply unit 11, and outputs control signals to the supply unit 11.

[0022] Since the wet powder having voids is dried, the coverage rate may not reach a predetermined value or more, but this coverage rate and the thickness of the coating layer can be adjusted by the number of coatings. The number of coatings may be appropriately selected depending on the coverage rate and the thickness of the coating layer, and may be, for example, 3 or more times, 5 or more times, or 10 or less times.

[0023] In the powder manufacturing apparatus 10, the heating unit 13 is disposed in the supply unit 11, but a heating unit for heating the fluid may be disposed in one or more of the first circulation unit 16, the first cyclone unit 21, the second circulation unit 22, and the second cyclone unit 24. The heating unit may be disposed anywhere in the apparatus as appropriate depending on the temperature of the fluid. Note that if the heating unit 13 is disposed only in the supply unit 11, the configuration of the apparatus can be simplified.

[0024] The operation of the powder manufacturing apparatus 10 will now be described. First, an operator prepares a wet powder by wetting powder with a liquid containing a functional material to a solid volume fraction in a range where dilatancy or a slurry state does not occur, for example, a range greater than 40% by volume, and places the wet powder in the supply unit 11. Next, the operator inputs processing conditions, such as the gas supply rate, heating temperature, and wet powder supply rate, into the control unit 28 and initiates a start input. The control unit 28 controls the supply unit 11 and other components according to the set processing conditions. Figure 3 is a schematic diagram of the powder manufacturing apparatus 10 when wet powder is introduced. A fluid containing the wet powder and heated gas supplied from the supply unit 11 flows through the mixing unit 17 and the flow pipe 18 and enters the first cyclone unit 21. The fluid flows and stagnates in the first cyclone unit 21 in a vortex pattern, where the agglomerated powder is crushed and dried. The powder that reaches the bottom of first cyclone section 21 flows into second cyclone section 24 via second circulation section 22. The fluid flows in a vortex shape and remains in second cyclone section 24, and the dried powder falls downward to be collected in collection section 25.

[0025] (Method for producing powder) The powder manufacturing method disclosed herein is a method for manufacturing powder in which the surface of the powder is coated with a functional material, and includes a supplying step of supplying a fluid containing a wet powder obtained by wetting the powder with a liquid containing the functional material and a heated gas, one or more cyclone steps of circulating the supplied fluid and then causing the fluid to flow and remain, and a collecting step of collecting the powder contained in the fluid after the cyclone step. This manufacturing method may include one cyclone step or two or more cyclone steps. Below, we will first mainly describe a powder manufacturing method that performs a first cyclone step and a second cyclone step.

[0026] The powder manufacturing method of the present disclosure is a method for manufacturing powder whose surface is coated with a functional material. This manufacturing method includes a supplying step, a first cyclone step, a second cyclone step, and a collecting step. This manufacturing method may be performed by the powder manufacturing apparatus 10 described above. This manufacturing method may further include a wet powder manufacturing step of wetting the powder with a liquid containing the functional material to produce a wet powder. In this wet powder manufacturing step, the powder may be wetted with a liquid containing the functional material so that the solid volume fraction is equal to or greater than the range in which dilatancy does not occur, for example, greater than 40% by volume.

[0027] (Supply process) In the supplying step, a fluid containing a wet powder obtained by wetting a powder with a liquid containing a functional material and a heated gas is supplied. In this step, a wet powder having a solid volume fraction of more than 40% by volume may be supplied. Furthermore, the solid volume fraction of the wet powder may be equal to or greater than the range in which dilatancy does not occur, depending on the properties of the powder, or may be in a range greater than 40% by volume. In addition to the functional material and powder, the processing conditions and the like may be appropriately the same as those explained in the powder manufacturing apparatus described above. In this step, the gas may be supplied at a temperature in the range of 100°C to 230°C. Furthermore, in this step, a gas having a temperature in the range of 0.5 m 3 / min or more, preferably 0.8m 3 / min more than 7.5m 3 / min or less.

[0028] (First cyclone process) In the first cyclone process, the supplied fluid is circulated and then retained while flowing. In this process, the fluid can be made to flow in a vortex or spiral shape by flowing the fluid perpendicular to the cylinder. In this process, wet particles are dried and powder particles are crushed by colliding with each other, preventing particle aggregation.

[0029] (Second cyclone process) In the second cyclone process, the fluid from the first cyclone process is passed through and then retained while flowing. This process separates the dried powder from the gas flow. In this process, the fluid is introduced perpendicular to the cylinder, allowing the fluid to flow in a vortex or spiral shape.

[0030] (Collection process) The collection step involves carrying out a process for collecting powder contained in the fluid after the second cyclone step. This process may involve collecting powder that has been separated from the gas flow in the second cyclone process and fallen down.

[0031] In this manufacturing method, a series of coating processes including the above-mentioned supplying process, first cyclone process, second cyclone process, and collection process may be repeated multiple times. By performing the coating process multiple times, the coverage rate of the functional material layer on the powder surface can be further increased. The number of times this coating process is performed can be determined depending on the coverage rate.

[0032] The powder production apparatus 10 and powder production method of the present embodiment, described in detail above, enable the formation of a more uniform functional material layer on the powder surface through more efficient processing. The reason for this effect is presumably as follows: Generally, in static drying, the liquid containing the functional material flows downward due to gravity, resulting in a thicker protective layer and a higher coverage rate for particles at the bottom, potentially resulting in uneven coverage. Furthermore, particles in areas with a higher concentration of the functional material-containing liquid tend to aggregate. On the other hand, in a method of air-flow drying of wet powder using a cyclone, the particles are introduced into the airflow while still wet with the liquid and are subjected to a disintegrating force due to the centrifugal force generated by the cyclone, resulting in the powder being dried while deagglomerated. In this way, the functional material-coated powder is prevented from agglomerating and has a uniform particle size. Furthermore, the use of multiple cyclones allows for sufficient drying and disintegration processes, presumably resulting in a more efficient and uniform formation of a functional material layer on the powder surface.

[0033] It goes without saying that the present disclosure is not limited to the above-described embodiments, and can be embodied in various forms as long as they fall within the technical scope of the present disclosure.

[0034] For example, in the above-described embodiment, the powder manufacturing apparatus 10 is described as having two cyclone units, but the present invention is not limited to this. As shown in FIG. 4, a powder manufacturing apparatus 10B having one first cyclone unit 21 may also be used. FIG. 4 is an explanatory diagram showing an example of another powder manufacturing apparatus 10B. In this powder manufacturing apparatus 10B, a collection unit 25, a filter 26, and a suction unit 27 are connected to the first cyclone unit 21. In this way, even an apparatus having one cyclone unit can form a more uniform functional material layer on the powder surface with more efficient processing.

[0035] In the above-described embodiment, a powder manufacturing method that performs two cyclone processes has been described, but this is not particularly limited, and a powder manufacturing method that performs only one cyclone process may also be used. In this way, even in a method that performs only one cyclone process, a more uniform functional material layer can be formed on the powder surface with more efficient processing. [Example]

[0036] Hereinafter, an example will be described in which a powder manufacturing apparatus according to the present disclosure is specifically fabricated and a powder manufacturing method is carried out using this powder manufacturing apparatus.

[0037] First, the powder production apparatus 10 shown in Fig. 1 and the powder production apparatus 10B shown in Fig. 4 were fabricated. In the fabricated powder production apparatus 10, the volume of the storage section 12 was 1 L, the total length of the first flow section 16 was 80 cm, the length L of the first cyclone section 21 was 40 cm and its volume was 0.4 L, the total length of the second flow section 22 was 45 cm, and the length of the second cyclone section 24 was 30 cm and its volume was 0.2 L. There are no limitations on the size of each component as long as the configuration is not changed.

[0038] Example 1 As the positive electrode active material, Li 1.14 (Ni 0.34 Co 0.34 Mn 0.31 20 g of LiNbO2 (also called NCM) was placed in a mixer container, and a coating solution containing LiNbO3 as a protective material was added to the positive electrode active material powder in a predetermined amount so that the solid volume fraction was 54.9% by volume, and the mixture was stirred with a spoon. The mixture was stirred in the mixer, and any residue on the wall was scraped off. This process was repeated three times, and the resulting mixture was used as a wet powder. The prepared wet powder sample was introduced little by little from the top of the powder production apparatus 10B (Figure 4), and airflow drying was carried out. Air heated to 220°C was blown in at a speed of 0.6 m. 3 The wet powder was supplied at a flow rate of 120 g / min, with a total weight of 20 g (powder only) at a supply rate of 120 g / min. This series of coating treatments, consisting of wetting and airflow drying, was repeated three times to obtain an active material powder (coated powder) with a protective layer formed thereon, designated Example 1. The time from sample introduction to drying and collection was 0.2 minutes per drying treatment.

[0039] Example 2 As the positive electrode active material, Li 1.14 (Ni 0.34 Co 0.34 Mn 0.3120 g of LiNbO2 (also called NCM) was placed in a mixer container, and a coating solution containing LiNbO3 as a protective material was added to the positive electrode active material powder in a predetermined amount so that the solid volume fraction was 49.5% by volume, and the mixture was stirred with a spoon. The process of stirring with the mixer and scraping off any residue that adhered to the wall was repeated three times, and the resulting mixture was used as a wet powder. The prepared wet powder sample was introduced little by little from the top of the powder production device 10 (Figs. 1 and 2) and airflow dried. Air heated to 220°C was blown in at a speed of 0.6 m. 3 The wet powder was fed at a flow rate of 120 g / min, with a total weight of 20 g (powder only) at a feed rate of 120 g / min. The time from sample loading to drying and collection was 0.21 minutes. The coated powder with a protective layer formed obtained through this series of processes was designated Example 2.

[0040] Example 3 20 g of NCM was placed in a mixer container, and a predetermined amount of coating liquid containing LiNbO3 was added so that the solid volume fraction was 49.5% by volume, and the mixture was stirred with a spoon. The mixture was stirred in the mixer, and any residue on the wall was scraped off. This process was repeated three times to prepare a wet powder sample. The prepared wet powder sample was introduced little by little from the top of the coating dryer, and air-flow drying was carried out. This series of coating processes, consisting of wetting and air-flow drying, was repeated three times to obtain the coated powder shown in Example 3.

[0041] (Comparative Example 1) 30 g of NCM was placed in a beaker, and a predetermined amount of coating liquid containing LiNbO3 was added so that the solid volume fraction was 40.5% by volume. The mixture was stirred with a spoon to obtain a slurry sample. The prepared slurry sample was introduced little by little from the top of the powder production apparatus 10, and air-dried. The air-dried conditions were the same as in Example 1. The obtained coated powder was designated Comparative Example 1.

[0042] (Comparative Example 2) A protective layer-forming active material powder was produced using a tumbling fluidized coating apparatus 110 shown in FIG. 5. FIG. 5 is an explanatory diagram showing an example of a known tumbling fluidized coating apparatus 110. The tumbling fluidized coating apparatus 110 includes a supply unit 111, a discharge unit 112, a stirring unit 113, a chamber 114, and a heater 115. This tumbling fluidized coating apparatus 110 supplies powder from the supply unit 111 at the bottom, and when the powder stirred by the stirring unit 113 is blown up into the chamber 114 above, a coating liquid is discharged from the discharge unit 112 and dried by the heater 115 provided above the chamber 114. 1000 g of NCM was loaded into the tumbling fluidized coating apparatus 110 and coated for 80 minutes while spraying 720 g of a coating liquid containing LiNbO. The resulting coated powder was designated Comparative Example 2.

[0043] (Comparative Example 3) 20 g of NCM was placed in a mixer container, and a predetermined amount of coating liquid containing LiNbO3 was added so that the solid volume fraction was 49.5% by volume, followed by stirring with a spoon. The process of stirring with the mixer and scraping off any residue from the wall was repeated three times to prepare a wet powder sample. This powder was spread in a petri dish, and the dish was heated in a muffle furnace from 80°C to 200°C over 30 minutes, then held at 200°C for 1 hour to dry. The powder was then crushed appropriately with a spatula and collected. The resulting coated powder was designated Comparative Example 3.

[0044] Comparative Example 4 20 g of NCM was placed in a mixer container, and a predetermined amount of coating liquid containing LiNbO3 was added so that the solid volume fraction was 49.5% by volume. The mixture was then stirred with a spoon. The process of stirring with the mixer and scraping off any residue from the wall was repeated three times to prepare a wet powder sample. This powder was spread in a petri dish, and the dish was heated in a muffle furnace from 80°C to 200°C over 30 minutes, then held at 200°C for 1 hour to dry. The powder was then crushed with a spatula and collected. The coated powder obtained by repeating this series of coating processes, from wetting to drying in a muffle furnace, three times was designated Comparative Example 4.

[0045] (Coverage calculation) The coverage of the coated powder was determined by performing surface elemental analysis of the obtained coated powder using X-ray photoelectron spectroscopy (XPS: PHI X-tool, manufactured by ULVAC-PHI), and calculating the coverage by applying the detected intensity values ​​of C1S, O1S, Nb3d, Mn2p3, Co2p3, Ni2p3, etc. to the following formula (1).

[0046]

number

[0047] (Measurement of particle diameter D90) The particle size (μm) of the powder after coating was determined as the particle size D90, which is the 90% particle size in the cumulative distribution, using a laser diffraction / scattering measuring device (Aerotrac II, manufactured by Microtrac-Bell).

[0048] (Results and Discussion) Table 1 summarizes the conditions for Examples 1 to 3 and Comparative Examples 1 to 4, such as the drying method, powder state, number of coatings, and wetting and drying treatment times. Table 2 also summarizes the coverage and particle size for Examples 1 to 3 and Comparative Examples 1 to 4. Examples 1 to 3 and Comparative Examples 1, 3, and 4 are the results of investigating a manufacturing method in which the wetting and drying processes are separated. Comparative Example 2 is the result of investigating a manufacturing method in which the wetting and drying processes are integrated. In Example 1, a wet powder with a solid volume fraction of 54.9% by volume was dried using a powder manufacturing apparatus with a single cyclone coating dryer (Figure 4). In Examples 2 and 3, a wet powder with a solid volume fraction of 49.5% by volume was dried using a powder manufacturing apparatus with a double cyclone coating dryer (Figure 1). It was found that when the coating process was repeated multiple times, as in Example 3, the coverage could be further increased with a high yield. Furthermore, the results for Example 1 were similar to those for Examples 2 and 3. In Comparative Example 1, a powder production apparatus similar to that used in Example 2 was used. However, because the powder used as the raw material was in the form of a slurry with a low solids volume fraction, as shown in Figure 6, the slurry adhered to the inner wall of the glass cylinder, taking a long time to dry. Furthermore, the yield was low because the slurry remained on the beaker and spoon. Figure 6 is a photograph of the state of the slurry from Comparative Example 1 adhering to the inside of the apparatus. In Comparative Example 2, a powder was produced using a tumbling fluidized coating apparatus, and the coverage and particle size were similar to those of Examples 2 and 3. On the other hand, Comparative Example 2 was produced using a batch processing apparatus for powder (1 kg), and the size of the fluidized kiln alone was 70 cm in height. Furthermore, when the processing volume is increased, for example, in an apparatus for processing 25 kg, the height of the fluidized kiln alone becomes 2.2 m, making the apparatus larger and the processing time longer. In Comparative Examples 3 and 4, static drying was used, but the drying time was long, the coverage was low, and particles aggregated.

[0049] [Table 1]

[0050] [Table 2]

[0051] As described above, the tumbling fluidized coating device required time and space to form a functional layer on the powder surface. However, the powder production device 10, 10B of the present disclosure was found to enable shortening of processing time and downsizing of the device. The powder production device 10, 10B used airflow drying, which significantly reduced the processing time from powder input to collection of the coated powder, compared to other devices. Furthermore, the use of a constant volume feeder enabled continuous powder input, enabling continuous coating processing. Because continuous processing was possible, large quantities could be processed. Furthermore, the powder production device 10, 10B was found to be capable of producing coated particles with a high coverage rate, uniformity, and suppressed particle aggregation. Furthermore, the thickness of the coating layer could be adjusted by changing the number of coatings. In addition, tests other than those mentioned above have shown that the production conditions for the wet powder and the airflow drying conditions are suitable for a solid volume fraction of more than 40% by volume, and the drying airflow temperature is in the range of 100°C to 230°C at the inlet, and the airflow rate is 0.5 m 3 / min or more, preferably 0.8m 3 / min more than 7.5m 3 / min or less was found to be preferable.

[0052] Coating powder surfaces with protective layers or functional materials is a highly useful technique for protecting powders and providing new functions. It is widely used in many technical fields involving powders, such as battery materials and magnetic materials. Positive electrode active materials in all-solid-state lithium-ion secondary batteries, for example, often experience a reaction between the active material and the solid electrolyte during repeated charge and discharge, resulting in a decrease in output characteristics. Therefore, coating the active material surface with a protective layer of lithium ion conductive metal oxide effectively reduces this reaction resistance. A uniform coating of the protective layer on the active material while suppressing the aggregation of the coated powder can suppress the deterioration of the positive electrode and extend the battery life. In this example, a powder production apparatus using a single-cyclone or double-cyclone coating dryer was used to coat the active material of a lithium-ion secondary battery as an example. However, this technique is widely applicable and can also be used to coat other powder surfaces with different materials uniformly, suppress particle aggregation, and quickly and efficiently.

[0053] It goes without saying that the present disclosure is not limited to the above-described embodiments, and can be embodied in various forms as long as they fall within the technical scope of the present disclosure. [Industrial Applicability]

[0054] The present disclosure is applicable in the technical field of batteries. [Explanation of symbols]

[0055] 10, 10B powder manufacturing apparatus, 11 supply section, 12 storage section, 13 heating section, 16 first circulation section, 17 mixing section, 18 circulation pipe, 21 first cyclone section, 22 second circulation section, 24 second cyclone section, 25 collection section, 26 filter, 27 suction section, 28 control section, 110 tumbling fluidized coating device, 111 supply section, 112 discharge section, 113 stirring section, 114 chamber, 115 heater, L total length.

Claims

1. A powder manufacturing apparatus for coating a surface of powder with a functional material, a supply unit that stores wet powder obtained by wetting the powder with a liquid containing the functional material and supplies a fluid containing the wet powder and heated gas; a first circulating portion connected to the supply portion and circulating the fluid without stagnation; a heating section disposed upstream of the first flow section in a fluid flow direction and configured to heat the fluid; one or more cyclone sections that cause the fluid supplied from the first circulation section to flow and remain there; a collecting section connected to the cyclone section and configured to collect powder contained in the fluid after the fluid has accumulated; A powder manufacturing device equipped with the above.

2. the cyclone unit includes a first cyclone unit and a second cyclone unit, the first cyclone portion connected to the first flow portion and causing the fluid to flow and accumulate; a second circulating section connected to the first cyclone section and through which the fluid circulates after stagnation; the second cyclone portion connected to the second flow portion and causing the fluid to flow and accumulate; the collection unit connected to the second cyclone unit; The powder manufacturing apparatus according to claim 1 ,

3. 3. The powder manufacturing apparatus according to claim 2, wherein the first circulation section includes a mixing section connected to the supply section and having a larger volume than the first cyclone section, and a circulation pipe connecting the mixing section and the first cyclone section.

4. 4. The powder manufacturing apparatus according to claim 1, wherein the supply unit accommodates and supplies the wet powder having a solid volume fraction in the range of more than 40% by volume.

5. 5. The powder manufacturing apparatus according to claim 1, wherein the supply unit supplies the gas at a temperature in the range of 100° C. or higher and 230° C. or lower.

6. The supply section is 0.5 m 3 / min or more 7.5m 3 6. The powder manufacturing apparatus according to claim 1, wherein the fluid is supplied at a rate of 1 / min or less.

7. The powder manufacturing apparatus according to any one of claims 1 to 6, wherein the powder is active material particles of an electricity storage device, the functional material is a protective material for the active material, and a protective layer including the protective material is formed on the surface of the active material particles.

8. A method for producing powder in which the surface of the powder is coated with a functional material, comprising the steps of: a supplying step of supplying a fluid containing wet powder obtained by wetting the powder with a liquid containing the functional material and a gas heated by a heating unit that heats the fluid; a first circulating step of circulating the fluid supplied in the supplying step without allowing it to stagnate; one or more cyclone steps in which the supplied fluid is passed through and then retained while flowing; a collecting step of collecting powder contained in the fluid after the cyclone step; A method for producing a powder comprising:

9. The cyclone process includes: a first cyclone step in which the supplied fluid is circulated and then retained while flowing; The method for producing powder according to claim 8, further comprising a second cyclone step of circulating the fluid after the first cyclone step and then retaining the fluid while it flows.

10. The method for producing powder according to claim 8 or 9, wherein the wet powder having a solid volume fraction of more than 40% by volume is supplied in the supplying step.

11. The method for producing powder according to any one of claims 8 to 10, wherein the gas is supplied at a temperature in the range of 100°C or higher and 230°C or lower in the supplying step.

12. In the supplying step, 0.5 m 3 / min or more 7.5m 3 The method for producing powder according to any one of claims 8 to 11, wherein the fluid is supplied at a rate in the range of / min or less.

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