Apparatus for the production of active material composite powder and method for the production of active material composite powder

Abstract

Device (100) for producing an active material composite powder (30) by coating surfaces of active material particles or composite particles obtained by coating the surfaces of the active material particles (31) with an oxide-based solid electrolyte (32) with a sulfide-based solid electrolyte (33), wherein the device (100) comprises: a storage body (11) which has a cylindrical inner wall surface (12), and a rotating body (13) which is arranged in an interior space which is surrounded by the inner wall surface (12) of the storage body (11), which has a rotating shaft (14) which is aligned with a central axis (X) of the interior space, and which has a plurality of leaves (15), wherein an end part (19) of each sheet (15) has on a front side in a direction of rotation of the rotating body (13) such that a thickness (24) of the sheet (15) gradually tapers towards a sheet end side, characterized by the fact that the end part (19) of each sheet (15) on a back side in the direction of rotation of the rotating body (13) has such a curved end surface (21) that the curved end surface (21) faces the inner wall surface (12) of the storage body (11) and is generally parallel to the inner wall surface (12) of the storage body (11), and a width (23) of the curved end surface (21) of the end part (19) of each sheet (15) lies in a range of 1 / 3 to 0.7 relative to the thickness (24) of the sheet (15).

Description

Technical field

[0001] The invention relates to a device for producing an active material composite powder and a method for producing an active material composite powder. State of the art

[0002] In the field of all-solid-state batteries (i.e., batteries that are exclusively in the solid state), there is an attempt to improve the performance of all-solid-state batteries by focusing on the interface between the electrode active material and the solid electrolyte material.

[0003] Examples of conventional methods for coating the surfaces of active material-containing particles with a sulfide-based solid electrolyte include gas-phase processes such as pulsed laser deposition (PLD). However, the PLD process generally has a slow layer formation rate, resulting in very poor productivity and making it impractical. Furthermore, in the PLD process, the target of the sulfide-based solid electrolyte is converted into a plasma by laser irradiation. During this process, the composition of the sulfide-based solid electrolyte can change and is not maintained.

[0004] Examples of other methods for coating the surfaces of active material-containing particles with a sulfide-based solid electrolyte include medium-utilizing mixing / kneading processes such as a planetary mill. However, in such medium-utilizing mixing / kneading processes, mechanical damage occurs upon collision with the medium, and this can damage the surfaces of the active material-containing particles.

[0005] To avoid such mechanical damage, there is therefore a need for mixing / kneading processes that do not use a medium.

[0006] As a technique to solve the above problem, patent literature 1 discloses, for example, a method for obtaining a composite powder in which different types of powders are bonded by applying a mechanical actuation involving pressure and shear forces to a starting material powder consisting of different types of powders using a powder treatment device.

[0007] From patent literature 1, in particular, an active material composite powder manufacturing device is known which comprises the features specified in the preamble of claim 1. A powder manufacturing device with the features of the preamble of claim 1 is also known from patent literature 2. Patent literature 1: JP 2010 - 180 099 A Patent literature 2: JP 11 - 347 428 A

[0008] However, the use of the conventional active material composite powder manufacturing device as disclosed in patent literature 1 is problematic insofar as the internal resistance of a battery using the active material composite powder obtained in this way is large. Brief description of the invention

[0009] The invention was made in light of the above circumstances. One object of the invention is to provide a device capable of producing an active material composite powder that can reduce the internal resistance of a battery, and a method for producing the active material composite powder.

[0010] The device according to the invention for producing an active material composite powder has the features defined in claim 1.

[0011] In the device according to the invention for producing an active material composite powder, the width of the curved end surface of the end part of each sheet is preferably in a range of 1 / 3 to 1 / 2 relative to the thickness of the sheet.

[0012] In the device according to the invention for producing an active material composite powder, the length of the end part of each sheet in the radial direction of the rotating body is preferably 0.5 to 30 mm in the rotational shaft direction front view of the rotating body.

[0013] In the device according to the invention for producing an active material composite powder, the width of the curved end surface of the end part of each sheet is preferably 0.5 to 30 mm.

[0014] In the device according to the invention for producing an active material composite powder, the gap between the curved end surface of the end part of each sheet and the inner wall surface of the storage body is preferably 0.5 to 10 mm.

[0015] In the device according to the invention for producing an active material composite powder, the angle of inclination of the tapered section in the rotational shaft direction front view of the rotating body is preferably 10 to 80° with reference to a tangent line at an intersection between the inclined surface of the tapered section and the inner wall surface of the storage body.

[0016] The inventive method for producing the active material composite powder is a method in which the surfaces of active material particles or composite particles, which are obtained by coating the surfaces of the active material particles with an oxide-based solid electrolyte, are coated with a sulfide-based solid electrolyte by preparing the device for producing the active material composite powder, placing the sulfide-based solid electrolyte and either the active material particles or the composite particles into the storage body of the production device, and then rotating the rotating body.

[0017] In the inventive process for producing the active material composite powder, the active material particles are preferably particles containing at least one of the elements cobalt, nickel and manganese, and also containing the element lithium and the element oxygen.

[0018] According to the invention, a device capable of producing an active material composite powder that can reduce the internal resistance of a battery and a method for producing the active material composite powder can be provided. Brief description of the drawings Fig. Figure 1 is a schematic side view of the manufacturing device according to the invention. Fig. 2 is a schematic front view of a Fig. 1 of the rotated body shown. Fig. Figure 3 is a schematic view of leaves installed on a rotating shaft of a rotating body. Fig. Figure 4 is a schematic sectional view of an exemplary embodiment of an active material composite powder. Detailed description of the invention: 1. Device for producing active material composite powder

[0019] The device according to the invention for producing an active material composite powder is a device for producing an active material composite powder by coating the surfaces of active material particles or composite particles, which are obtained by coating the surfaces of the active material particles with an oxide-based solid electrolyte, with a sulfide-based solid electrolyte, wherein the device comprises: a storage body having a cylindrical inner wall surface, and a rotating body arranged in an interior space surrounded by the inner wall surface of the storage body, which has a rotating shaft aligned with a central axis of the interior space, and which has a plurality of leaves, wherein an end part of each leaf has a tapered section on a front side in a direction of rotation of the rotating body such that the thickness of the leaf gradually tapers towards a leaf end side.and the end part of each sheet on a back side in the direction of rotation of the rotating body has such a curved end surface that the curved end surface faces the inner wall surface of the storage body and is generally parallel to the inner wall surface of the storage body, and wherein a width of the curved end surface of the end part of each sheet is in a range of 1 / 3 to 0.7 based on the thickness of the sheet.

[0020] The inventor has discovered that the internal resistance of a battery can be reduced more than ever before by shaping the end part of each blade.The reason for this is probably as follows: Since the end part of each sheet has the tapered section on the front side in the direction of rotation of the rotating body, a starting material powder can be effectively fed into a treatment section (a tiny space between the end part of each sheet and the inner wall surface of the storage body); and since the end part of each sheet has such a curved end face on the back side in the direction of rotation of the rotating body that the curved end face faces the inner wall surface of the storage body and is generally parallel to the inner wall surface of the storage body, the time required to grind the starting material powder is increased for the width of the end face, thus increasing the efficiency of coating the surfaces of the active material particles or the composite particles described below with the sulfide-based solid electrolyte (coating efficiency).It is assumed that this will lower the internal resistance of a battery that uses the active material composite powder obtained in this way.

[0021] In the invention, “coating” means that 40% or more of the surface of each active material particle or composite particle is coated.

[0022] Furthermore, in the invention, the internal resistance means the sum of DC resistance, reaction resistance, diffusion resistance and other resistances.

[0023] The following describes an embodiment of the active material composite powder manufacturing device according to the invention.

[0024] Fig. Figure 1 is a schematic side view of an embodiment of the manufacturing device according to the invention.

[0025] As in Fig.As shown in Figure 1, a manufacturing device 100 comprises a storage body 11 which has a cylindrical inner wall surface 12 and a laterally extending central axis X (in Fig. (indicated by an alternating long and short dashed line) and a rotating body 13, which is arranged in the interior space surrounded by the inner wall surface 12 of the storage body 11 and is driven to rotate about the central axis X. The rotating body 13 has a rotating shaft 14 aligned with the central axis X and a plurality of blades 15 extending radially outwards from an outer circumferential portion of the rotating shaft 14. One end of the rotating shaft 14 is supported by a bearing 16 and is connected to a motor 17, which is a drive device. An opening is provided at the right end of the storage body 11 so that materials can be placed into the storage body 11 through the opening.

[0026] If required, the outer wall of the storage body 11 can be surrounded by a cooling tube to allow a (not shown) temperature control fluid to circulate.

[0027] Fig. 2 is a schematic front view of a Fig. 1 of the rotated body shown.

[0028] In Fig. 2 The arrow indicates the direction of rotation of the rotating body 13.

[0029] As in Fig. As shown in Figure 2, an end part 19 of each leaf 15 has a tapered section on the front side in the direction of rotation of the rotating body 13 such that the thickness of the leaf gradually tapers towards the end of the leaf.

[0030] As in Fig. 2 (also in the direction of rotation - front view of the in Fig.As shown in Figure 1 of the rotating body 13), the angle of inclination 20 of the tapered section is preferably 10 to 80° with respect to a tangent line L at an intersection between an extension line extending from an inclined surface 28 of the tapered section in the direction of inclination and the inner wall surface 12 of the storage body 11. From the perspective of increasing the amount of the starting material powder that is introduced into a space 22, the angle of inclination 20 is particularly 30 to 60°.

[0031] Furthermore, the end portion 19 of each sheet 15 has a curved end surface 21 on its reverse side in the direction of rotation of the rotating body 13 such that the curved end surface 21 faces the inner wall surface 12 of the storage body 11 and is generally parallel to the inner wall surface 12 of the storage body 11. Thus, by shaping the end surface 21 of the end portion 19 of each sheet 15 in the form of a curved surface that curves circularly around the inner wall surface 12 of the storage body 11, the space 22 between the end surface 21 of the end portion 19 of each sheet 15 and the inner wall surface 12 of the storage body 11 is generally kept constant over the entire length of the end surface 21. The reason for keeping the space 22 constant is to apply a uniform force to the powder. The reason for keeping the space 22 tiny is to apply a greater force to the powder by reducing the space through which the powder can pass.The spaces 22 between the inner wall surface 12 of the storage body 11 and the end parts 19 of the leaves 15 can vary depending on the positions where the leaves 15 are installed.

[0032] The gap (tiny space) 22 between the end face 21 of the end part 19 of each sheet 15 and the inner wall surface 12 of the storage body 11 is preferably 0.5 mm or more, in particular 1 mm or more, and preferably 10 mm or less, in particular 5 mm or less. If the gap 22 is more than 10 mm, the space through which the powder can pass increases, and it cannot exert strong mechanical stress on the powder. If, on the other hand, the gap 22 is less than 0.5 mm, the amount of powder that can be introduced into the gap 22 is small, so a long processing time is required, and there is an increase in manufacturing costs. In addition, the sheets 15 can come into contact with the storage body 11 due to unexpected vibration caused during operation by an overload, etc.

[0033] As in Fig. 2 (also in the direction of rotation - front view of the in Fig. 1 of the body of revolution 13 shown, a width 23 of the end face 21 of the end part 19 of each sheet 15 is 0.5 mm or more, in particular 1 mm or more, and preferably 30 mm or less, in particular 20 mm or less.

[0034] The thickness 24 of each sheet 15 is preferably 1 mm or more, better 2 mm or more, even better 5 mm or more, and preferably 100 mm or less, better 50 mm or less, even better 20 mm or less.

[0035] The width 23 of the end surface 21 of the end part 19 of each sheet 15 is in a range of 1 / 3 to 0.7, preferably in a range of 1 / 3 to 1 / 2, based on the thickness 24 of the sheet 15.

[0036] The length 25 of the end part 19 of each sheet 15 in the radial direction of the rotating body 13 is preferably 0.5 mm or more, better 1 mm or more, even better 3 mm or more, and preferably 30 mm or less, in particular 20 mm or less.

[0037] The total length 26 of each sheet 15 is preferably 10 mm or more, in particular 15 mm or more, and preferably 600 mm or less, in particular 400 mm or less.

[0038] The length 25 of the end part 19 of each sheet 15 is preferably in a range of 0.002 to 1, or better, in a range of 0.05 to 0.95, relative to the total length 26 of each sheet 15.

[0039] The diameter 27 of the rotating shaft 14 of the rotating body 13 is preferably 30 mm or more, in particular 40 mm or more, and preferably 1000 mm or less, in particular 500 mm or less.

[0040] Fig. Figure 3 is a schematic view of leaves installed on a rotating shaft of the rotating body. The one in Fig. The arrow shown in Figure 3 indicates the direction of rotation of the rotating body.

[0041] As in Fig. As shown in Figure 3, each blade 15 is installed parallel to the rotating shaft 14.

[0042] Each blade 15 can be installed at an angle to the rotating shaft 14. The number of blades 15 installed on the rotating shaft 14 is not particularly limited. It can be suitably determined depending on the size of the device, the quantity of starting powder fed into the manufacturing device, etc. 2. Method for the production of active material composite powder

[0043] The inventive method for producing the active material composite powder is a method in which the surfaces of active material particles or composite particles, which are obtained by coating the surfaces of the active material particles with an oxide-based solid electrolyte, are coated with a sulfide-based solid electrolyte by preparing the production device, placing the sulfide-based solid electrolyte and either the active material particles or the composite particles into the storage body of the production device, and then rotating the rotating body.

[0044] The manufacturing device that can be used in the manufacturing process according to the invention is not described here, since it is the same as the device described under “1. Device for the production of active material composite powder”.

[0045] The temperature inside the storage body is not particularly limited. The temperature is preferably controlled to 100°C or less.

[0046] The circumferential speed of the rotating body is preferably 10 to 30 m / s.

[0047] The rotation time of the rotating body is not particularly limited. It can, for example, range from 30 seconds to 3 hours.

[0048] The quantity of starting material powder added to the storage body is preferably set within a range of 5 to 95% of the internal volume of the treatment chamber within the storage body, so that the powder within the storage body is effectively subjected to stirring. The internal volume of the treatment chamber within the storage body refers to the volume of a space determined by subtracting the volume occupied by the rotating body from the internal volume of the storage body itself (i.e., the substantial space within the storage body in which the powder can move around).

[0049] The amount of sulfide-based solid electrolyte added is not particularly limited. It preferably amounts to 5 to 25 parts by mass per 100 parts by mass of the active material particles or per 100 parts by mass of the composite particles.

[0050] The manufacturing process according to the invention is advantageous in that it offers a cost reduction, since it is a dry mixing process that does not require a dispersion medium, etc. (1) Active material particles

[0051] The active material particles are not particularly restricted as long as they can serve as an electrode active material, more precisely as long as they can occlude and / or release ions, such as lithium ions.

[0052] Examples of cathode-active material particles include: layered active materials such as LiCoO2, LiNiO2, LiCo 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, LiVO2 and LiCrO2; spinel-like active materials such as LiMn2O4, Li(Ni 0,25 Mn 0,75 )2O4, LiCoMnO4 and Li2NiMn3O8; olivine-like active materials such as LiCoPO4, LiMnPO4 and LiFePO4; and NASICON-like active materials such as Li3V2P3O 12Preference is given to those containing at least one of the elements cobalt, nickel, and manganese, and which also contain the elements lithium and oxygen, i.e., LiCoO2, LiNiO2, LiCo 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, LiMn2O4, Li(Ni 0,25 Mn 0,75 )2O4, LiCoMnO4, Li2NiMn3O8, LiCoPO4 and LiMnPO4. Among these, LiNi is particularly included. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 preferred.

[0053] Examples of anode active material particles include: carbon-containing materials such as mesophase carbon microbeads (MCMB), graphite, highly oriented pyrolytic graphite (HOPG), hard carbon and soft carbon; oxides such as Nb2O5, Li4Ti5O 12and SiO₂; metallic lithium (Li); lithium alloys such as LiM (where M is Sn, Si, Al, Ge, Sb, P or the like); and metals such as In, Al, Si and Sn. Among these, preferably carbon-containing materials such as graphite, highly oriented pyrolytic graphite (HOPG), hard carbon and soft carbon are used.

[0054] In the invention, there is no clear distinction between the cathode active material and the anode active material. By comparing the charging / discharging potentials of two types of compounds and using the one with a noble potential in the cathode and the one with a less noble potential in the anode, a battery with a desired voltage can be formed.

[0055] In the invention, the active material particles can be single-crystal particles of an active material, or they can be polycrystalline active material particles in which active material single crystals are bonded to one another at the crystal plane level.

[0056] In the invention, the mean particle diameter of the active material particles is not particularly limited, as long as it is smaller than the mean particle diameter of the targeted active material composite powder. The mean particle diameter of the active material particles is preferably 0.1 to 30 µm. If the active material particles are polycrystalline active material particles in which active material single crystals are bonded together, the mean particle diameter of the active material particles refers to the mean particle diameter of the polycrystalline active material particles.

[0057] In the invention, the mean particle diameter is calculated using a general method. An example of this method is as follows. First, for a particle shown in an image taken with a transmission electron microscope (hereinafter referred to as TEM) or a scanning electron microscope (hereinafter referred to as SEM) at a suitable magnification (e.g., 50,000× to 1,000,000×), the diameter is calculated, assuming the particle is spherical. Such a particle diameter calculation by TEM or SEM examination is performed on 200 to 300 particles of the same type, and the mean of the particles is determined to be the mean particle diameter. (2) Compound particles

[0058] In the invention, the composite particles are particles obtained by coating the surfaces of the active material particles with the oxide-based solid electrolyte. If the oxide-based solid electrolyte is positioned between the sulfide-based solid electrolyte and the active material particles, deterioration of the reaction due to contact between the sulfide-based solid electrolyte and the active material particles can be prevented.

[0059] The active material particles contained in the composite particles are preferably particles containing at least one of the elements cobalt, nickel, and manganese, and also containing lithium and oxygen. In particular, LiCoO2, LiNiO2, and LiCo are used. 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, LiMn2O4, Li(Ni 0,25 Mn 0,75 )2O4, LiCoMnO4, Li2NiMn3O8, LiCoPO4 and LiMnPO4 preferred. LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 is particularly preferred.

[0060] The oxide-based solid electrolyte contained in the composite particles is not particularly limited, as long as it contains the element oxygen (O) and has sufficient chemical affinity for the active material particles to coat at least part of the surface of each active material particle. Examples of oxide-based solid electrolytes include those described by the general formula Li x AO y can be represented (where AB, C, Al, Si, P, S, Ti, Zr, Nb, Mo, Ta or W, and x and y are positive integers). In particular, Li3BO3, LiBO2, Li2CO3, LiAlO2, Li4SiO4, Li2SiO3, Li3PO4, Li2TiO3, Li4Ti5O 12 Examples include Li₂Ti₂O₅, Li₂ZrO₃, LiNbO₃, Li₂MoO₄, Li₂WO₄, etc. Other examples include Li₂O-B₂O₃-P₂O₅, Li₂O-SiO₂, Li₂O-B₂O₃, Li₂O-B₂O₃-ZnO, etc. The use of LiNbO₃ is particularly preferred.

[0061] The thickness of the oxide-based solid electrolyte layer coating the active material particles is preferably such that it prevents any reaction between the sulfide-based solid electrolyte and the active material particles. For example, it is preferably in the range of 0.1 to 100 nm, or even better, in the range of 1 to 20 nm.

[0062] The oxide-based solid electrolyte layer should coat 40% or more of the surface of each active material particle. Preferably, the oxide-based solid electrolyte layer coats a larger surface area of ​​each active material particle. Better yet, the layer coats the entire surface of each active material particle. The coating rate is particularly 70% or more, better still 90% or more.

[0063] Examples of methods for forming the oxide-based solid electrolyte layer on the surfaces of the active material particles include tumbling / fluidized coating (sol-gel coating), mechano-melting, chemical vapor deposition (CVD), and physical vapor deposition (PVD). Thermal electron microscopy (TEM) is one example of a method for measuring the thickness of the oxide-based solid electrolyte layer. TEM and X-ray photoelectron spectroscopy (XPS) are examples of methods for measuring the deposition rate of the oxide-based solid electrolyte layer. (3) Sulfide-based solid electrolyte

[0064] The sulfide-based solid electrolyte used in the invention is not particularly limited as long as it contains the element sulfur (S); has a chemical affinity for the above-mentioned active material particles or composite particles to such an extent that it coats the surfaces of the active material particles or composite particles; and has ionic conductivity.

[0065] The thickness of the sulfide-based solid electrolyte layer coating the surfaces of the active material particles or composite particles is, for example, preferably in the range of 0.1 to 1,000 nm, or even better in the range of 1 to 500 nm.

[0066] The sulfide-based solid electrolyte layer should coat 40% or more of the surface of each active material particle or composite particle. Preferably, the sulfide-based solid electrolyte layer coats a larger surface area of ​​each particle. Even better, the sulfide-based solid electrolyte layer coats the entire surface of each active material particle or composite particle. The coating rate is particularly preferably 70% or more, and even better, 90% or more. The coating condition of the sulfide-based solid electrolyte can be qualitatively verified by TEM, SEM, etc.

[0067] The form of the sulfide-based solid electrolyte used for mixing / kneading is not particularly restricted. A particulate form is preferred.

[0068] In the case that the active material composite powder of the invention is used in an all-solid-state lithium battery as the sulfide-based solid electrolyte, examples include Li2S-SiS2-based solid electrolytes, Li2S-P2S3-based solid electrolytes, Li2S-P2S5-based solid electrolytes, Li2S-GeS2-based solid electrolytes, Li2S-B2S3-based solid electrolytes, Li3PO4-P2S5-based solid electrolytes and Li4SiO4-Li2S-SiS2-based solid electrolytes. Specifically, the following can be identified: Li2S-P2S5, Li2S-P2S3, Li2S-P2S3-P2S5, Li2S-SiS2, Li2S-P2S5-LiI, LiI-Li2S-SiS2-P2S5, LiI-LiBr-Li2S-P2S5, LiI-LiBr-Li2S-SiS2-P2S5, Li2S-SiS2-Li4SiO4, Li2S-SiS2-Li3PO4, Li2S-GeS2, Li3PS4-Li4GeS4, LiGe O,25 P O,75 S4, Li2S-B2S3, Li 3,4 P 0,6 Si 0,4 S4, Li 3,25 P 0,25 Ge 0,76 S4, Li 4-X Ge 1-X P X S4 and Li7P3S 11 They are called. Among them, Li2S-P2S5-LiI is preferred.

[0069] The sulfide-based solid electrolyte can be a sulfide glass or a crystallized sulfide glass obtained by heating a sulfide glass.

[0070] Fig. Figure 4 is a schematic sectional view of an embodiment of the active material composite powder provided by the invention. The purpose of Fig. Figure 4 is to qualitatively describe the material coating condition in an exemplary embodiment, and it does not represent a view that qualitatively depicts the particle size of the actual solid electrolyte, the coating condition of the solid electrolyte, the thickness of the solid electrolyte layer, etc.

[0071] As in Fig.As shown in Figure 4, the active material composite powder 30 contains composite particles in which all surfaces of the active material particles 31 are coated with an oxide-based solid electrolyte layer 32 and all surfaces of the composite particles are coated with a sulfide-based solid electrolyte layer 33.

[0072] The active material composite powder provided by the invention can be used in electrode active material layers (cathode and anode active material layers) and is preferably used in the electrode active material layers of an all-solid-state battery. This is because electrode active material layers with excellent electrode conductivity and high charge / discharge capacity can be achieved.

[0073] Examples of methods for forming electrode active material layers include a process for compression molding an electrode mixture containing the active material composite powder. For example, an all-solid-state battery can be manufactured by stacking a cathode mixture and an anode mixture on top of each other over a solid electrolyte layer.

[0074] The process for producing the electrode mixture is not particularly limited. For example, it can be produced by mixing an active material composite powder, an electrically conductive material, and a binder in a desired ratio.

[0075] The content of the active material composite powder in the electrode mixture is preferably in the range of 10 to 99 percent by mass.

[0076] The electrically conductive material is not particularly limited, as long as it can increase the electrical conductivity of electrodes.

[0077] Examples of electrically conductive materials include carbon black, Ketjen Black, and carbon fibers. The content of the electrically conductive material in the electrode mixture varies depending on the type of electrically conductive material. It generally ranges from 1 to 30 percent by mass.

[0078] The electrode mixture may contain a binder if required. Examples of binders include fluorinated resins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), as well as elastic resins such as butadiene rubber (BR). There are no particular restrictions on the elastic resins, and preferably a hydrogenated butadiene rubber or a hydrogenated butadiene rubber with a functional group introduced in one end group may be used. These may be used alone or in combination with two or more types. The binder content in the electrode mixture should be sufficient to fix the cathode active material, etc., and is preferably low. The binder content is generally in the range of 1 to 10 percent by mass.

[0079] The method for mixing them is not particularly restricted and can be wet mixing or dry mixing.

[0080] In the case of wet mixing, a process can be described in which the active material composite powder, the electrically conductive material, the sulfide-based solid electrolyte particles, the binder, and a dispersion medium are mixed to produce a slurry, and the slurry is then dried. Examples of dispersion media include butyl butyrate, butyl acetate, dibutyl ether, heptane, etc.

[0081] In the case of dry mixing, for example, a process can be mentioned in which the active material composite powder, the electrically conductive material, the sulfide-based solid electrolyte particles and the binder are mixed with a mortar or the like.

[0082] The electrode active material layer formed from the electrode mixture can be equipped with a current collector. The design and shape of the current collector, as well as the material used for it, are not particularly restricted, as long as the current collector has the desired electron conductivity. Examples of materials suitable for the current collector include gold, silver, palladium, copper, and nickel.

[0083] The active material composite powder provided by the invention can be used in various other types of batteries besides lithium secondary batteries, depending on the materials used (electrode active material, solid electrolyte, etc.). Examples - Example 1 -

[0084] First, composite particles were produced (average particle diameter 6 µm) containing LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2 particles (active material particles) were coated with LiNbO3 (oxide-based solid electrolyte).

[0085] Next, 20 g of the composite particles and 4 g of 60Li2S-20P2S5-20LiI particles (sulfide-based solid electrolyte, mean particle diameter 0.8 µm) were placed in a dry mixing / kneading machine (product name: NOB-MINI, manufactured by: Hosokawa Micron Corporation) and mixed and kneaded for 10 minutes using the following conditions, producing an active material composite powder. Thickness of each sheet: 6 mm Width of the end face of the end part of each sheet: 1 mm Length of the end part of each sheet: 5.0 mm Total length of each sheet: 18.9 mm Diameter of the rotating shaft of the rotating body: 50 mm Gap: 1 mm Tilt angle: 45° Peripheral speed: 18.5 m / s

[0086] It should be noted that Example 1 is outside the scope of protection of claim 1. - Example 2 -

[0087] With the exception that the width of the end face of the end part of each sheet was changed to 2.5 mm and the thickness of each sheet was changed to 7.5 mm, an active material composite powder was produced in the same way as in Example 1. - Example 3 -

[0088] With the exception that the width of the end surface of the end part of each sheet was changed to 5 mm and the thickness of each sheet was changed to 10 mm, an active material composite powder was produced in the same way as in Example 1. - Comparison example 1 -

[0089] First, composite particles were produced (average particle diameter 6 µm) containing LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 particles (active material particles) were coated with LiNbO3 (oxide-based solid electrolyte).

[0090] Next, 20 g of the composite particles and 4 g of 60Li2S-20P2S5-20LiI particles (sulfide-based solid electrolyte, mean particle diameter 0.8 µm) were subjected to dry mixing (spatula mixing) for 10 minutes, producing an active material composite powder. - Comparison example 2 -

[0091] With the exception that the thickness of each sheet was changed to 1 mm and no tapered section was formed at the end part of each sheet (i.e., the thickness of each sheet and the width of the end surface of the end part of each sheet were both set to 1 mm), an active material composite powder was produced in the same way as in Example 1. - Comparison example 3 -

[0092] With the exception that the thickness of each sheet was changed to 2.5 mm and no tapered section was formed at the end part of each sheet (i.e., the thickness of each sheet and the width of the end surface of each end part of each sheet were both set to 2.5 mm), an active material composite powder was produced in the same way as in Example 1. - Comparison example 4 -

[0093] With the exception that the thickness of each sheet was changed to 5 mm and no tapered section was formed at the end part of each sheet (i.e., the thickness of each sheet and the width of the end surface of the end part of each sheet were both set to 5 mm), an active material composite powder was produced in the same way as in Example 1. -- Battery manufacturing --

[0094] Subsequently, all-solid-state lithium secondary batteries were produced using the active material composite powders of Examples 1 to 3 and the comparative examples 1 to 4 as the cathode active material.

[0095] The active material composite powders were prepared as the cathode active material; 60Li2S-20P2S5-20LiI particles were prepared as a sulfide-based solid electrolyte; vapor-grown carbon fibers (VGCF) were prepared as the electrically conductive material; and PVdF was prepared as a binder. The cathode active materials, the sulfide-based solid electrolyte, the electrically conductive material, and the binder were each prepared in the following ratio: cathode active material / sulfide-based solid electrolyte / electrically conductive material / binder = 81.3 wt% / 16.6 wt% / 1.3 wt% / 0.8 wt%. Then, 13 g of butyl butyrate were added, and the mixture was wet-mixed for 2 minutes using an ultrasonic homogenizer to produce a cathode mixture.

[0096] 60Li2S-20P2S5-20LiI particles (sulfide-based solid electrolyte) were used as the starting material for a separator layer (solid electrolyte layer).

[0097] Natural graphite was used as the anode active material; 60Li₂S-20P₂S₅-20LiI particles were used as the sulfide-based solid electrolyte; and PVdF was used as the binder. The anode active material, the sulfide-based solid electrolyte, and the binder were prepared in the following ratio: anode active material / sulfide-based solid electrolyte / binder = 54.8 wt% / 43.4 wt% / 1.8 wt%. Then, 13 g of butyl butyrate were added, and the mixture was wet-mixed for 2 minutes using an ultrasonic homogenizer to produce an anode mixture.

[0098] A separator layer was first formed by pressing the 60Li2S-20P2S5-20LiI particles. Next, the cathode mixture was applied to one surface of the pressable powder, and the anode mixture to the other. The resulting structure was then pressed for 1 minute at a pressure of 6 t / cm². 2 (≈ 588 MPa) was subjected to flat pressing, resulting in a laminate. In the laminate obtained in this way, the thickness of the cathode mixture layer was 30 µm; the thickness of the anode mixture layer was 45 µm; and the thickness of the separator layer was 300 µm. The laminate was held in the layering direction at a pressure of 0.2 N, thus producing an all-solid-state lithium secondary battery.

[0099] In the following, the all-solid-state lithium secondary batteries in which the active material composite powders of Examples 1 to 3 and Comparative Examples 1 to 4 were used as starting material are referred to as the all-solid-state lithium secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 4. -- Measurement of internal resistance of all-solid-state lithium secondary batteries --

[0100] For the all-solid-state lithium secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 4, the internal resistance was measured using the 10s DCIR method. The details of the measurement procedure were as follows. Open-circuit voltage potential: 3.52 V Current density: 15.7 mA / cm² 2

[0101] The internal resistance was calculated using Ohm's law based on the overvoltage and the voltage value measured 10 seconds after discharge.

[0102] The internal resistances of the all-solid-state lithium secondary batteries of examples 1 to 3 and comparison examples 1 to 4 are given in Table 1. Table 1 tapered section Angle of inclination (°) Leaf thickness (mm) Width of end surface of end part (mm) Length of end section (mm) Internal resistance (Ω / cm) 2 ) Example 1 Trained 45 6 1 5 100,1 Example 2 Trained 45 7,5 2,5 5 81 Example 3 Trained 45 10 5 5 72,8 Comparative example 1 - - - - - 149,8 Comparative example 2 Untrained - 1 1 - 120,2 Comparative example 3 Untrained - 2,5 2,5 - 104,7 Comparative example 4 Untrained - 5 5 - 110,3

[0103] As shown in Table 1, the internal resistances of the all-solid-state lithium secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 4 were as follows: 100.1 Ω / cm 2 In example 1; 81.0 Ω / cm 2 In example 2; 72.8 Ω / cm 2 in example 3; 149.8 Ω / cm 2 In comparative example 1; 120.2 Ω / cm 2 In comparative example 2; 104.7 Ω / cm 2 in comparative example 3; and 110.3 Ω / cm 2 in comparative example 4.

[0104] As shown in Table 1, the internal resistances of the all-solid-state lithium secondary batteries of Examples 1 to 3 were 33 to 51% smaller than the internal resistance of Comparative Example 1, in which the apparatus for producing the active material composite powder was not used.

[0105] Furthermore, the internal resistances of the all-solid-state lithium secondary batteries of Examples 1 to 3 were 4 to 39% smaller than those of the all-solid-state lithium secondary batteries of Comparison Examples 2 to 4, which used the blades that did not have a tapered section at their end part.

[0106] A comparison of Example 1 and Comparative Example 2, in which the active material composite powder was produced under the condition that the width of the end face of each sheet was 1 mm, shows that the internal resistance of the all-solid-state lithium secondary battery of Example 1 is 17% lower than that of the all-solid-state lithium secondary battery of Comparative Example 2. A comparison of Example 2 and Comparative Example 3, in which the active material composite powder was produced under the condition that the width of the end face of each sheet was 2.5 mm, shows that the internal resistance of the all-solid-state lithium secondary battery of Example 2 was 23% lower than that of the all-solid-state lithium secondary battery of Comparative Example 3.A comparison of Example 3 and Comparative Example 4, in which the active material composite powder was produced under the condition that the width of the end face of each sheet was 5 mm, shows that the internal resistance of the all-solid-state lithium secondary battery of Example 3 is 34% lower than that of the all-solid-state lithium secondary battery of Comparative Example 4. It is therefore clear that, if the widths of the end faces of the sheet end pieces are the same, the internal resistance will be 17 to 34% lower, depending on the presence of the tapered section.

[0107] Comparing examples 1 to 3 shows that the internal resistance of the all-solid-state lithium secondary battery of example 3 is the lowest and that the resistance of the all-solid-state lithium secondary battery of example 2 is the smallest after example 3.

[0108] It is therefore clear that the tapered section and the increase in the width of the end surface of the end part of each sheet increase the coating efficiency and reduce the internal resistance of the all-solid-state lithium secondary battery.

[0109] It follows from the above that the active material composite powder produced using the device according to the invention for producing the active material composite powder has the function of reducing the internal resistance of a battery more than conventional active material composite powders. Reference symbol list 11 storage bodies 12 interior wall area 13 Rotating Bodies 14 Rotary shaft 15 sheets 16 warehouses 17 Engine 19 End of the sheet 20 Inclination angle of the tapered section 21 End surface of the end part of the sheet 22 space 23 Width of the end surface of the end part of the sheet 24 Thickness of the leaf 25 Length of the end part of the sheet 26 Total length of the sheet 27 Diameter of the rotating shaft of the rotating body 28 inclined surface of the tapered section 30 active material composite powders 31 active material particles 32 oxide-based solid electrolyte layer 33 sulfide-based solid electrolyte layer 100 Device

Claims

Device (100) for producing an active material composite powder (30) by coating surfaces of active material particles or composite particles obtained by coating the surfaces of the active material particles (31) with an oxide-based solid electrolyte (32) with a sulfide-based solid electrolyte (33), wherein the device (100) comprises: a storage body (11) having a cylindrical inner wall surface (12), and a rotating body (13) arranged in an interior space surrounded by the inner wall surface (12) of the storage body (11), the rotating body having a rotating shaft (14) aligned with a central axis (X) of the interior space, and the rotating body having a plurality of sheets (15), wherein an end part (19) of each sheet (15) has a tapered section on a front side in a direction of rotation of the rotating body (13) such that a thickness (24) of the sheet (15) gradually decreases tapered towards one end of the leaf,characterized in that the end part (19) of each sheet (15) has a curved end surface (21) on its back side in the direction of rotation of the rotating body (13) such that the curved end surface (21) faces the inner wall surface (12) of the storage body (11) and is generally parallel to the inner wall surface (12) of the storage body (11), and a width (23) of the curved end surface (21) of the end part (19) of each sheet (15) lies in a range of 1 / 3 to 0.7 based on the thickness (24) of the sheet (15). Device (100) for producing the active material composite powder (30) according to claim 1, wherein a width (23) of the curved end surface (21) of the end part (19) of each sheet (15) is in a range of 1 / 3 to 1 / 2 based on the thickness (24) of the sheet (15). Device (100) for producing the active material composite powder (30) according to claim 1 or 2, wherein in a rotational shaft direction front view of the rotating body (13) a length (25) of the end part (19) of each sheet (15) in the radial direction of the rotating body (13) is 0.5 to 30 mm. Device (100) for producing the active material composite powder (30) according to one of claims 1 to 3, wherein the width (23) of the curved end surface (21) of the end part (19) of each sheet (15) is 0.5 to 30 mm. Device (100) for producing the active material composite powder (30) according to one of claims 1 to 4, wherein a gap (22) between the curved end surface (21) of the end part (19) of each sheet (15) and the inner wall surface (12) of the storage body (11) is 0.5 to 10 mm. Device (100) for producing the active material composite powder (30) according to one of claims 1 to 5, wherein in the rotational shaft direction front view of the rotating body (13) an inclination angle (20) of the tapered section is 10 to 80° with respect to a tangent line (L) at an intersection between an inclined surface (28) of the tapered section and the inner wall surface (12) of the storage body (11). Method for producing an active material composite powder (30), wherein surfaces of active material particles or composite particles obtained by coating the surfaces of the active material particles (31) with an oxide-based solid electrolyte (32) are coated with a sulfide-based solid electrolyte (33) by preparing the production device (100) as defined in any one of claims 1 to 6, placing the sulfide-based solid electrolyte (33) and either the active material particles (31) or the composite particles into the storage body (11) of the production device (100) and then rotating the rotating body (13). Method for producing the active material composite powder (30) according to claim 7, wherein the active material particles (31) are particles containing at least one of the elements cobalt, nickel and manganese and also containing the element lithium and the element oxygen.

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