Manufacturing device and manufacturing method of positive electrode active material for lithium ion secondary battery

Abstract

The present disclosure is a manufacturing device and a manufacturing method for a positive electrode active material for a lithium-ion secondary battery. Provided is a manufacturing device for a positive electrode active material for a lithium-ion secondary battery, which is capable of improving productivity, the manufacturing device comprising a conveying unit and a heating section, the conveying unit conveying a positive electrode active material, the positive electrode active material comprising a lithium compound and a metal compound, the metal compound comprising at least one metal element selected from nickel, cobalt, and manganese, the heating section heating the positive electrode active material, the heating section having at least one heating unit, the heating unit heating the positive electrode active material by heat conduction, the conveying unit having a conveying member that conveys the positive electrode active material, the heating unit heating the positive electrode active material across the conveying member, the conveying member having a positive electrode active material holding section at an end portion in a width direction.

Description

Technical Field

[0001] This application relates to an apparatus and a method for manufacturing positive electrode active materials for lithium-ion secondary batteries. Background Technology

[0002] Lithium-ion rechargeable batteries are widely used in power supplies for laptops, portable devices, and vehicles. Therefore, there is a need to improve the productivity of lithium-ion rechargeable batteries, as well as the productivity of the positive electrode active materials used in them.

[0003] A typical method for manufacturing positive electrode active materials for lithium-ion secondary batteries is as follows. First, a metal hydroxide containing nickel, etc., which will serve as a precursor, is mixed with a lithium compound (e.g., lithium hydroxide, lithium carbonate, etc.) to obtain a positive electrode active material. Next, the positive electrode active material is pre-fired (simulated firing) to oxidize it. Specifically, the metal hydroxide is oxidized to a metal oxide, and the lithium compound is oxidized to lithium oxide. Then, the pre-fired positive electrode active material is filled into a prescribed crucible and fired. During firing, the metal oxide and lithium oxide in the positive electrode active material react to obtain lithium metal oxide, which serves as the positive electrode active material. Furthermore, the obtained positive electrode active material is recycled and utilized in lithium-ion secondary batteries. For example, such a method for manufacturing positive electrode active materials is disclosed in Patent Documents 1-3.

[0004] In the pre-firing process of the positive electrode active material, a firing apparatus such as a rotary kiln is used. A rotary kiln is a device that can simultaneously stir and heat the positive electrode active material in an oxidizing atmosphere, thereby promoting the oxidation of the positive electrode active material. The reason for pre-firing the positive electrode active material is that the oxidation reaction of metal hydroxides and lithium compounds is an endothermic reaction; therefore, it is to prevent uneven temperature distribution of the positive electrode active material due to the endothermic reaction during the firing process.

[0005] In the firing process of the positive electrode active material, a firing apparatus such as a roller hearth kiln is used. The roller hearth kiln can heat the positive electrode active material at a higher temperature than in the pre-firing process, and can manufacture the positive electrode active material by reacting the metal oxide and lithium oxide in the material. Furthermore, pressure can be applied to increase the density of the positive electrode active material when filling it into the sagger. By increasing the density of the positive electrode active material, the contact area between the metal oxide and lithium oxide in the material increases, thus promoting firing.

[0006] Prior art literature

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2020-113429

[0009] Patent Document 2: Japanese Patent Application Publication No. 2019-175694

[0010] Patent Document 3: Japanese Patent Application Publication No. 2020-198195 Summary of the Invention

[0011] Since rotary kilns are used to oxidize metal hydroxides and / or lithium compounds, it is necessary to actively feed air or oxygen into the kiln to create an oxidizing atmosphere. However, this active feeding of air or oxygen increases production costs.

[0012] A roller hearth furnace is a device used to sinter pre-fired positive electrode active material. To ensure uniform heating, the positive electrode active material needs to be filled into a sagger. However, due to the flow pattern of hot air within the furnace, the positive electrode active material is prone to temperature inhomogeneity. When heating the positive electrode active material for a short time while it is under these uneven temperatures, the crystallinity of the manufactured positive electrode active material deviates. Therefore, when using a roller hearth furnace to manufacture positive electrode active materials, prolonged heating of the material is necessary to suppress temperature inhomogeneity, which increases production costs. Furthermore, the need for prolonged heating necessitates the large-scale construction of the equipment.

[0013] Therefore, the purpose of this application is to provide an apparatus and method for manufacturing positive electrode active materials for lithium-ion secondary batteries that can improve productivity.

[0014] As a means of solving the above-mentioned problems, this disclosure provides an apparatus for manufacturing positive electrode active material for lithium-ion secondary batteries, which includes a transport unit for transporting positive electrode active material material and a heating section for heating the positive electrode active material material. The positive electrode active material material includes a lithium compound and a metal compound, wherein the metal compound includes at least one metal element selected from nickel, cobalt and manganese. The heating section has at least one heating unit for heating the positive electrode active material material by heat conduction. The transport unit has a transport member for transporting the positive electrode active material material. The heating unit heats the positive electrode active material material via the transport member. The transport member has a positive electrode active material holding section at its end in the width direction.

[0015] In the aforementioned manufacturing apparatus, the heating unit may be a heating roller. Alternatively, in the aforementioned manufacturing apparatus, the heating unit may consist of multiple heating rollers, with heating rollers that heat one side of the positive electrode active material and heating rollers that heat the other side of the positive electrode active material alternately arranged from the upstream side to the downstream side in the transport direction, and adjacent heating rollers arranged facing each other in a manner that clamps the positive electrode active material between them. Furthermore, the wrap angle of the heating rollers may exceed 180° and be less than 360°.

[0016] In the aforementioned manufacturing apparatus, the heating section can heat the positive electrode active material to a temperature of 700°C or higher and 1000°C or lower. Alternatively, the heating section can heat the positive electrode active material under an oxidizing atmosphere.

[0017] In the aforementioned manufacturing apparatus, the transport component may be made of a porous heat-resistant component.

[0018] In the aforementioned manufacturing apparatus, a forming unit for shaping the positive electrode active material into a sheet shape may be provided upstream of the heating section in the transport direction. Additionally, the aforementioned manufacturing apparatus may also include a recovery section for recovering the positive electrode active material obtained through the heating section.

[0019] As a means of solving the above-mentioned problems, this disclosure provides a method for manufacturing a positive electrode active material for lithium-ion secondary batteries, which includes a positive electrode active material material preparation step and a heating step for heating the positive electrode active material material. In the positive electrode active material material preparation step, a lithium compound and a metal compound are mixed to obtain a positive electrode active material material, wherein the metal compound includes at least one metal element selected from nickel, cobalt, and manganese. In the heating step, the positive electrode active material material is heated by heat conduction. In the heating step, the positive electrode active material material is transported by a transport member and heated through the transport member. The transport member has a positive electrode active material holding portion at its end in the width direction.

[0020] In the above manufacturing method, the positive electrode active material can be heated while being transported during the heating process. Furthermore, in the above manufacturing method, the heating process can alternately heat both sides of the positive electrode active material and heat only one side of the positive electrode active material. Moreover, in the heating process of the above manufacturing method, a heating roller with a wrap angle exceeding 180° and less than 360° can be used to heat the positive electrode active material.

[0021] In the above manufacturing method, during the heating step, the positive electrode active material can be heated to 700°C or higher and 1000°C or lower. Alternatively, in the above manufacturing method, during the heating step, the positive electrode active material can be heated under an oxidizing atmosphere.

[0022] In the above manufacturing method, the transport component can be made of a porous heat-resistant component.

[0023] In the above manufacturing method, a forming step for shaping the positive electrode active material into a sheet shape can be included before the heating step. Additionally, the above manufacturing method may also include a recovery step for recovering the positive electrode active material obtained through the heating step.

[0024] According to this disclosure, the manufacturing productivity of positive electrode active materials can be improved. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of an apparatus 100 for manufacturing positive electrode active materials for lithium-ion secondary batteries.

[0026] Figure 2 It is a cross-sectional view in the width direction showing the way the positive electrode active material 1 slides down from the end of the transport member 11.

[0027] Figure 3 This is a cross-sectional view in the width direction of the transport member 11, which has a positive electrode active material holding part 12a.

[0028] Figure 4 This is a cross-sectional view in the width direction of the transport member 11, which has a positive electrode active material holding part 12b.

[0029] Figure 5 It is a cross-sectional view in the width direction of the transport member 11 having a positive electrode active material holding part 12c.

[0030] Figure 6 It is a cross-sectional view in the width direction of the transport member 11 having a positive electrode active material holding part 12d.

[0031] Figure 7 This is a diagram used to illustrate the wrap angle x of the heating roller 31.

[0032] Figure 8 This is an enlarged view of the heating roller 31.

[0033] Figure 9 This is a schematic diagram of an apparatus 200 for manufacturing positive electrode active materials for lithium-ion secondary batteries.

[0034] Figure 10 This is a diagram used to illustrate the wrap angle x of the heating roller 131.

[0035] Figure 11 This is an enlarged view of the heating roller 131 and the contact roller 132.

[0036] Figure 12 This is a schematic diagram of an apparatus 300 for manufacturing positive electrode active materials for lithium-ion secondary batteries.

[0037] Figure 13 This is a flowchart of a method 1000 for manufacturing positive electrode active material for lithium-ion secondary batteries.

[0038] Figure 14 This is a flowchart of the manufacturing method of positive electrode active material for lithium-ion secondary batteries 2000.

[0039] Figure 15 This is a flowchart of method 3000 for manufacturing positive electrode active material for lithium-ion secondary batteries.

[0040] Explanation of reference numerals in the attached figures

[0041] 1: Positive electrode active material

[0042] 2: Positive electrode active material

[0043] 10: Delivery Unit

[0044] 11: Transporting components

[0045] 12a, 12b, 12c, 12d: Positive electrode active material holding section

[0046] 20: Forming Unit

[0047] 30, 130, 230: Heating section

[0048] 31, 131: Heating roller (heating unit)

[0049] 31d: Protrusion

[0050] 40: Recycling Department

[0051] 41: Roller

[0052] 132: Contact Roller

[0053] 231: Plate heating unit (heating unit)

[0054] 100, 200, 300: Manufacturing apparatus for positive electrode active materials for lithium-ion secondary batteries Detailed Implementation

[0055] 1. Manufacturing apparatus for positive electrode active material for lithium-ion secondary batteries

[0056] The apparatus for manufacturing the positive electrode active material for lithium-ion secondary batteries disclosed herein will be described with reference to the following first to third embodiments.

[0057] [First Implementation Method]

[0058] Figure 1A schematic diagram is shown of an apparatus 100 for manufacturing positive electrode active material for lithium-ion secondary batteries according to the first embodiment (sometimes referred to as "manufacturing apparatus 100" in this specification). Here, Figure 1 The left and right directions are used as the transport direction, the up and down direction is used as the height direction, and the front and back direction (inside and outside direction) is used as the width direction.

[0059] like Figure 1 As described, the manufacturing apparatus 100 includes a transport unit 10, a forming unit 20, a heating unit 30, and a recovery unit 40. Furthermore, in Figure 1 The document describes positive electrode active material 1 as a raw material and positive electrode active material 2 as a product.

[0060] <Positive Electrode Active Material 1>

[0061] The positive electrode active material 1 is a material containing metal compounds and lithium compounds. Alternatively, it may contain degraded and fragmented positive electrode active material 2, such as recycled materials. Even with degraded positive electrode active material 2, it can be sintered in the heating section 30 with high heat homogeneity.

[0062] The positive electrode active material 1 can be obtained by mixing these materials. The mixing method is not particularly limited and can be any known method. For example, a mortar and pestle can be used for mixing, or a blender can be used for mixing.

[0063] (Metallic compounds)

[0064] A metal compound is a compound containing at least one metallic element selected from nickel, cobalt, and manganese. Additionally, a metal compound may contain nickel, nickel and cobalt, or nickel, cobalt, and manganese. Furthermore, it may contain other metallic elements. For example, a metal compound may also contain aluminum. Alternatively, a metal compound may contain aluminum instead of manganese.

[0065] For example, in a metallic compound, the molar ratio of each metallic element can be Ni:Co:Mn = x:y:z (x = 1 - y - z, 0 ≤ y < 1, 0 ≤ z < 1), or Ni:Co:Al = x:y:z (x = 1 - y - z, 0 ≤ y < 1, 0 ≤ z < 1).

[0066] The metal compound can be a metal hydroxide, metal oxide, metal carbonate, or metal perhydroxide. These metal compounds can be used alone or in combination. Preferably, the metal compound is a metal hydroxide or metal oxide.

[0067] As a metal hydroxide, known metal hydroxides containing at least one metallic element selected from nickel, cobalt, and manganese can be used. Examples include Ni. x Co y Mn z (OH) 2+α (x = 1 - y - z, 0 ≤ y < 1, 0 ≤ z < 1, 0 ≤ α < 1), and Ni x Co y Al z (OH) 2+α (x = 1 - y - z, 0 ≤ y < 1, 0 ≤ z < 1, 0 ≤ α < 1). As a metal oxide, known metal oxides containing at least one metallic element selected from nickel, cobalt, and manganese can be used. Examples include Ni. x Co y Mnz(O) 2+α (x = 1 - y - z, 0 ≤ y < 1, 0 ≤ z < 1, -1 ≤ α < 0), and Ni x Co y Al z (O) 2+α (x=1-y-z, 0≤y<1, 0≤z<1, -1≤α<0).

[0068] Metal compounds can be prepared using known methods. Examples of methods for preparing metal hydroxides and metal oxides are shown below. However, the methods for preparing metal compounds are not limited to these.

[0069] For example, crystallization can be used as a method for preparing metal hydroxides. The following describes an example of a method for preparing metal hydroxides using crystallization.

[0070] First, a metal source solution is prepared by dissolving the Ni, Co, and Mn (or Al) sources in an aqueous solvent (e.g., deionized water). Various metal salts (i.e., Ni, Co, and Mn (or Al) salts) can be used as metal sources. The type of metal salt is not particularly limited; known metal salts such as hydrochlorides, sulfates, nitrates, carbonates, and hydroxides can be used. The order in which these metal sources are added to the aqueous solvent is not particularly limited. Alternatively, aqueous solutions of each metal source can be prepared separately and then mixed. The proportions of the metal sources are appropriately adjusted to obtain the desired metal hydroxide.

[0071] Next, under an inert gas atmosphere, a metal source solution and an aqueous NH3 solution are added dropwise to the alkaline aqueous solution while stirring. The alkaline aqueous solution can be an aqueous sodium hydroxide solution, etc. The pH of the alkaline aqueous solution is set to, for example, 11 to 13. The aqueous NH3 solution is added dropwise while maintaining a concentration of, for example, 5 g / L to 15 g / L. Since the pH of the reaction solution gradually decreases by adding the metal source solution and the aqueous NH3 solution to the alkaline aqueous solution, the pH can also be maintained within a specified range by appropriately adding the alkaline aqueous solution.

[0072] Then, after a certain period, suction filtration is performed to recover the precipitate. The obtained precipitate is then washed with water and dried to obtain the metal hydroxide. The water washing of the precipitate can be performed multiple times. The precipitate can be dried by air drying or by heating. Heating can be carried out at temperatures, for example, 120–300°C. The drying time is, for example, 6–18 hours.

[0073] Metal oxides can be produced by oxidative roasting, for example, metal hydroxides. Oxidative roasting involves heating the metal hydroxide under an oxidizing atmosphere. The heating temperature is not particularly limited as long as it is sufficient to convert the metal hydroxide into a metal oxide; for example, it can be 700°C to 800°C. The heating time is also not particularly limited as long as it is sufficient to convert the metal hydroxide into a metal oxide; for example, it can be 0.5 hours to 3 hours. Such heating can be carried out using a firing apparatus such as a rotary kiln.

[0074] The average particle size of the metal compound is not particularly limited, for example, it is in the range of 1 μm to 1 mm. In this specification, the term "average particle size" refers to the particle size at which the cumulative value of the particle size distribution on a volume basis obtained by laser diffraction-scattering method is 50%, i.e., the median particle size.

[0075] The proportion of metal compounds in the positive electrode active material is appropriately set to obtain the desired positive electrode active material.

[0076] (Lithium compounds)

[0077] Lithium compounds are not particularly limited to any compound containing lithium; well-known lithium compounds can be used. Examples include lithium oxide, lithium hydroxide, lithium nitrate, and lithium carbonate. Lithium hydroxide, lithium nitrate, and lithium carbonate can be oxidized to lithium oxide.

[0078] The type of lithium compound is appropriately selected based on the type of metal compound. This is because the heating temperature (firing temperature) varies depending on the type of metal compound. For example, when using metal hydroxides or metal oxides containing nickel, cobalt, and manganese as the metal compound, a firing temperature of around 800°C is required, so lithium carbonate is preferred. Conversely, when using metal hydroxides or metal oxides containing nickel, cobalt, and aluminum as the metal compound, a firing temperature of around 500°C is required, so lithium hydroxide is preferred.

[0079] The proportion of lithium compounds in the positive electrode active material is appropriately set to obtain the desired positive electrode active material.

[0080] (Shape of positive electrode active material 1)

[0081] The shape of the positive electrode active material 1 is not particularly limited and can be sheet-like. By making the positive electrode active material 1 sheet-like, it becomes easier to heat it evenly to the interior. As a result, heating unevenness is reduced, and deviations in the crystallinity of the manufactured positive electrode active material 2 are suppressed. In addition, by making the positive electrode active material 1 sheet-like, it can be easily broken down in the recovery section 40.

[0082] The thickness of the sheet-like positive electrode active material 1 is not particularly limited. For example, it can be 0.1 mm or more, 0.5 mm or more, 1 mm or more, 2 mm or more, less than 50 mm, less than 30 mm, less than 30 mm, less than 20 mm, less than 10 mm, or less than 5 mm. If the sheet-like positive electrode active material 1 is too thick, it will be difficult to heat it uniformly; if it is too thin, the productivity will decrease.

[0083] The positive electrode active material 1 can be formed into a sheet using the forming unit 20 and / or the heating roller 31, but it can also be formed into a sheet in advance by pressing or the like. However, the positive electrode active material 1 can also be formed into a sheet in advance, and then the positive electrode active material 1 can be formed into a specified thickness using the forming unit 20 and / or the heating roller 31.

[0084] <Transportation Unit 10>

[0085] The transport unit 10 is a component used to transport the positive electrode active material 1. For example... Figure 1 As shown, the transport unit 10 includes a transport member 11 for transporting the positive electrode active material 1. Additionally, it includes a drive unit (not shown) for driving the transport member 11.

[0086] (Transporting component 11)

[0087] The transport member 11 is a component (transfer type) for transporting the positive electrode active material 1. The transport member 11 is a sheet-like component, driven from the upstream side to the downstream side in the transport direction by a drive unit. The transport member 11 transports the positive electrode active material 1 in a state where it is loaded, therefore it needs to be positioned below the positive electrode active material 1. Alternatively, it can be as follows... Figure 1 As described, it is also disposed on top of the positive electrode active material 1. That is, the positive electrode active material 1 can be transported in a state where it is held by the transport member 11.

[0088] As will be described later, the manufacturing apparatus 100 heats the positive electrode active material 1 by contact heating. Therefore, the positive electrode active material 1 could be heated by direct contact with the heating roller 31, but this would cause the positive electrode active material 1 to adhere to the heating roller 31, resulting in a decrease in productivity. Therefore, in the manufacturing apparatus 100, by having the heating roller 31 contact the positive electrode active material 1 through the transport member 11, the adhesion of the positive electrode active material 1 to the heating roller 31 is suppressed. For this reason, the positive electrode active material 1 can be transported by clamping it with the transport member 11.

[0089] Since the conveying member 11 is in contact with the heating roller 31, it needs to be made of a component (heat-resistant component) that is resistant to the heating temperature of the heating section 30. For example, the heat-resistant component needs to have a heat resistance of 900°C or higher. Examples of such heat-resistant components include quartz glass cloth and silica fiber cloth.

[0090] In the case where the positive electrode active material 1 contains materials such as metal hydroxides and lithium hydroxides that are oxidized into oxides, oxygen needs to be introduced from the outside in order to carry out the firing of the positive electrode active material 1. Furthermore, the positive electrode active material 1 sometimes generates gases such as water (water vapor) and carbon dioxide during firing. Therefore, the firing of the positive electrode active material 1 is preferably carried out in an environment where gas exchange is possible. Therefore, the transport member 11 can also be made of a porous heat-resistant member capable of efficient gas exchange with the outside. The pore size of the porous heat-resistant member is not particularly limited as long as it allows for efficient gas exchange and prevents leakage of the positive electrode active material 1 to the outside. For example, the pore size of the porous heat-resistant member can be less than 20 μm, less than 10 μm, less than 5 μm, more than 3 μm, more than 1 μm, or more than 0.5 μm. If the pore size of the porous heat-resistant member is too large, the positive electrode active material 1 is prone to leakage to the outside; if it is too small, the efficiency of gas exchange with the outside is reduced. Examples of such porous heat-resistant components include fibrous heat-resistant components. Examples include quartz glass cloth and silica fiber cloth.

[0091] Here, the pore size of the porous heat-resistant component is the length of the diagonal of the mesh, calculated based on the fiber diameter and product density (unit: fibers / mm).

[0092] The transport member 11 serves to transport the positive electrode active material 1, but during transport, the positive electrode active material 1 sometimes slips off the end of the transport member 11. As described later, the manufacturing apparatus 100 uses a heating roller 31 to heat the positive electrode active material 1 through heat conduction (contact heating). At this time, the positive electrode active material 1 in the transport member 11 is subjected to a load in the vertical direction by being clamped by the opposing heating rollers 31. In addition, the positive electrode active material 1 in the transport member 11 is subjected to a predetermined tension while being transported in contact with the heating roller 31 at a predetermined wrap angle. As a result, there is a problem that the positive electrode active material 1 moves outward in the width direction and slips off the end of the transport member 11. Moreover, the lithium compound contained in the positive electrode active material 1, especially lithium carbonate, has a low melting point and sometimes melts and sol-states (liquefies) when heated. In this case, the positive electrode active material 1 becomes more prone to slipping off.

[0093] Figure 2 The diagram shows a cross-sectional view in the width direction, representing the appearance of the positive electrode active material 1 sliding off the end of the transport member 11. Figure 2 Corresponding to Figure 1 AA section. For example... Figure 2 As shown, the positive electrode active material 1 moves outward in the width direction by pressure from the heating roller 31 and slides off the end of the transport member 11.

[0094] To suppress such slippage, the transport member 11 has a positive electrode active material holding portion at one end in the width direction. The positive electrode active material holding portion can be provided at at least one end of the transport member 11 in the width direction, but from the viewpoint of further suppressing slippage of the positive electrode active material 1, it can also be provided at both ends of the transport member 11 in the width direction. Furthermore, the positive electrode active material holding portion can be provided on any one of the transport members 11 that hold the positive electrode active material 1, but from the viewpoint of further suppressing slippage of the positive electrode active material 1, it can also be provided on two transport members 11. Figures 3-6 The positive electrode active material holding sections 12a to 12d are shown as specific embodiments. Figures 3-6 Corresponding to Figure 1 AA section.

[0095] Figure 3This is a cross-sectional view in the width direction of the transport member 11, which includes a positive electrode active material holding portion 12a. The positive electrode active material holding portion 12a is formed by bending the end of the transport member 11. Figure 3 In the process, the positive electrode active material holding part 12a is formed by bending the ends of the transport members 11 disposed on the top and bottom of the positive electrode active material 1, respectively.

[0096] The overall thickness of the positive electrode active material holding portion 12a at a single end is not particularly limited and can be appropriately set according to the thickness of the positive electrode active material 1, but is preferably thicker than the thickness of the positive electrode active material 1. This is to concentrate the pressure of the heating roller 31 at the end, reduce the pressure applied to the positive electrode active material 1, and suppress the positive electrode active material 1 from moving outward in the width direction. For example, the overall thickness of the positive electrode active material holding portion 12a at a single end can be set to 110% or more and 200% or less of the thickness of the positive electrode active material 1. The thickness of the positive electrode active material holding portion 12a can be appropriately set according to the number of times the end of the conveying member 11 is folded. For example, the end of the conveying member 11 can be folded at least once. Figure 3 In the middle, each end was bent twice.

[0097] By having a positive electrode active material holding portion 12a in the conveying member 11, the positive electrode active material 1 can be pushed back inward in the width direction at the end, thus suppressing the slippage of the positive electrode active material 1. In addition, since the density of the conveying member 11 at the end is higher, when it contacts the heating roller 31, pressure is more easily applied to the end side compared to the center in the width direction, which can suppress the movement of the positive electrode active material 1 outward in the width direction, further suppressing the slippage of the positive electrode active material 1.

[0098] Figure 4 This is a cross-sectional view in the width direction of the transport member 11, which includes a positive electrode active material holding portion 12b. The positive electrode active material holding portion 12b is formed by weaving a heat-resistant preform 13b into the end of the transport member 11. Figure 4 In this process, the positive electrode active material holding section 12b is formed by weaving a heat-resistant blank 13b into the ends of the transport members 11 disposed above and below the positive electrode active material 1. The heat-resistant blank 13b is, for example, a rope-like wire made of quartz glass, silica fiber, or bundled metal fiber.

[0099] The overall thickness of the positive electrode active material holding portion 12b at a single end is not particularly limited and can be appropriately set according to the thickness of the positive electrode active material 1, but it is preferably thicker than the thickness of the positive electrode active material 1. This is to concentrate the pressure of the heating roller 31 at the end, reduce the pressure applied to the positive electrode active material 1, and suppress the positive electrode active material 1 from moving outward in the width direction. For example, the overall thickness of the positive electrode active material holding portion 12b at a single end can be set to be more than 110% and less than 200% of the thickness of the positive electrode active material 1. In addition, at the end of the conveying member 11, the heat-resistant blanks 13b arranged facing each other are arranged in an interlocking manner. As a result, it is possible to further suppress the slippage of the positive electrode active material 1.

[0100] By having a positive electrode active material holding portion 12b on the conveying member 11, the positive electrode active material 1 can be pushed back inward in the width direction at the end, thus suppressing the slippage of the positive electrode active material 1. In addition, since the strength of the conveying member 11 at the end is increased, when it contacts the heating roller 31, pressure is more easily applied to the end side compared to the center in the width direction, which can suppress the movement of the positive electrode active material 1 outward in the width direction, further suppressing the slippage of the positive electrode active material 1.

[0101] Figure 5 This is a cross-sectional view in the width direction of a transport member 11 having a positive electrode active material holding portion 12c. The positive electrode active material holding portion 12c is a guide member (transfer member) disposed at the end of the transport member 11 between opposing transport members 11. Furthermore, the positive electrode active material holding portion 12c is disposed along the transport direction of the transport member 11. Figure 5 In this configuration, the positive electrode active material holding portion 12c is disposed at each end of the transport member 11 between opposing transport members 11. The positive electrode active material holding portion 12c (guide member) is, for example, a heat-resistant member such as a glass fiber sheet.

[0102] The thickness of the positive electrode active material holding portion 12c is not particularly limited and can be appropriately set according to the thickness of the positive electrode active material 1, but it is preferably thicker than the thickness of the positive electrode active material 1. This is to concentrate the pressure of the heating roller 31 at the end, reduce the pressure applied to the positive electrode active material 1, and suppress the positive electrode active material 1 from moving outward in the width direction. For example, the thickness of the positive electrode active material holding portion 12c can be set to 110% or more and 200% or less of the thickness of the positive electrode active material 1.

[0103] By having a positive electrode active material holding portion 12c on the conveying member 11, the positive electrode active material 1 can be pushed back inward in the width direction at the end, thus suppressing the slippage of the positive electrode active material 1. In addition, since the strength of the conveying member 11 at the end is increased, when it contacts the heating roller 31, pressure is more easily applied to the end side compared to the center in the width direction, which can suppress the movement of the positive electrode active material 1 outward in the width direction, further suppressing the slippage of the positive electrode active material 1.

[0104] Figure 6 This is a cross-sectional view in the width direction of the transport member 11 having a positive electrode active material holding portion 12d. The positive electrode active material holding portion 12d is formed by narrowing the ends of the transport member 11 disposed above and below the positive electrode active material 1. Figure 6 In this configuration, the positive electrode active material holding portion 12d is formed by narrowing each end of the transport member 11. When the transport member 11 has the positive electrode active material holding portion 12d, a heating roller 31 with a protrusion 31d at the end corresponding to the positive electrode active material holding portion 12d is used. Figure 6 In the middle, a protrusion 31d is provided at each end of the heating roller 31.

[0105] The overall thickness of the protrusion 31d at a single end is not particularly limited and can be appropriately set according to the thickness of the positive electrode active material 1, but is preferably thicker than the thickness of the positive electrode active material 1. This is to concentrate the pressure of the heating roller 31 at the end, reduce the pressure applied to the positive electrode active material 1, and suppress the movement of the positive electrode active material 1 outward in the width direction. For example, the overall thickness of the protrusion 31d at a single end can be set to be more than 110% and less than 200% of the thickness of the positive electrode active material 1. By having protrusions 31d at both ends of the heating roller 31, a predetermined recess is formed in the heating roller 31. Figure 6 As shown, the positive electrode active material 1 is heated inside the recess. Therefore, the widths of the protrusion 31d and the recess are appropriately set according to the width of the positive electrode active material 1.

[0106] Thus, by combining the positive electrode active material holding portion 12d and the recess, the positive electrode active material 1 can be pushed back inward in the width direction at the end, thereby suppressing the slippage of the positive electrode active material 1. Furthermore, since pressure is easily applied to the end of the heating roller 31, movement of the positive electrode active material 1 outward in the width direction can be suppressed, further suppressing the slippage of the positive electrode active material 1. Moreover, the positive electrode active material holding portion 12d can be formed as a protrusion 31d, or it can be formed by pre-narrowing the end of the conveying member 11.

[0107] Furthermore, in Figure 6 In this configuration, the heating rollers 31 arranged on the upper and lower sides of the positive electrode active material 1 each have protrusions 31d, but this is not a limitation; any heating roller 31 may have a protrusion 31d. In this case, the protrusions 31d press the positive electrode active material holding part 12d against the other heating roller 31 that does not have a protrusion 31d. Thus, the aforementioned effect is achieved.

[0108] The above shows a specific example of the positive electrode active material holding section, but the shape of the positive electrode active material holding section is not limited to this; any shape that can suppress the slippage of the positive electrode active material 1 is acceptable. Furthermore, by having a positive electrode active material holding section in the transport member 11, the slippage of the positive electrode active material 1 can be suppressed. Therefore, according to the apparatus 100, the manufacturing productivity of the positive electrode active material 2 can be improved.

[0109] <Forming Unit 20>

[0110] The forming unit 20 is a component that shapes the positive electrode active material 1 into a sheet shape. For example... Figure 1 As described, the forming unit 20 is positioned upstream of the heating section 30 in the transport direction. Furthermore, in the manufacturing apparatus 100, the forming unit 20 is an arbitrary component. This is because, as described above, the positive electrode active material 1 can also be pre-formed into a sheet shape.

[0111] As forming unit 20, a powder quantity control component can be used to form a sheet-like structure by controlling the powder quantity of the transported positive electrode active material 1. For example, Figure 1 The powder quantity control tool described herein. Additionally, a component formed by pressing the positive electrode active material 1 into a sheet shape can be cited as an example.

[0112] The thickness of the sheet-like positive electrode active material 1 formed by the forming unit 20 is not particularly limited. For example, it can be 0.1 mm or more, 0.5 mm or more, 1 mm or more, 2 mm or more, less than 50 mm, less than 30 mm, less than 30 mm, less than 20 mm, less than 10 mm, or less than 5 mm.

[0113] <Heating section 30>

[0114] The heating section 30 is used to heat (fire) the positive electrode active material 1. For example... Figure 1 As described, the heating unit 30 has a rectangular housing and six heating rollers 31 (heating units) are provided inside the housing.

[0115] The heating unit 30 can heat the positive electrode active material 1 to 700°C or higher, 800°C or higher, 900°C or higher, 1100°C or lower, or 1000°C or lower. Anyone skilled in the art can set the temperature to appropriately sinter the positive electrode active material 1. The positive electrode active material 1 is heated by contact with the heating roller 31, as described later. Therefore, the heating roller 31 is actually heated to a predetermined temperature. Furthermore, the temperatures of the heating rollers 31 can be the same or different. For example, the heating roller 31 disposed on the upstream side of the transport direction can be set to a low temperature for oxidation purposes, while the heating roller 31 disposed on the downstream side of the transport direction can be set to a high temperature for sintering purposes.

[0116] The heating section 30 can also heat the positive electrode active material 1 in an oxidizing atmosphere. This is to promote the oxidation reaction of the positive electrode active material 1. To create an oxidizing atmosphere inside, the heating section 30 is equipped with an air supply section (not shown). By supplying air or oxygen into the interior of the heating section from the air supply section, the heating section 30 can be maintained in an oxidizing atmosphere. Alternatively, air or oxygen can be continuously supplied in a manner that maintains the heating section 30 at a negative pressure. A known blower or the like can be used as the air supply section. Furthermore, if the positive electrode active material does not contain materials that undergo an oxidation reaction, since it is not necessary to oxidize the positive electrode active material 1 in the heating section 30, it is not necessary to create an oxidizing atmosphere in the heating section 30.

[0117] In this specification, "oxidizing atmosphere" refers to an atmosphere capable of oxidizing the target material. For example, it could be an atmosphere in a space supplied with and filled with a gas containing 1% or more oxygen (e.g., air or oxygen). The oxygen concentration in the space can be appropriately set according to the rate of oxidation of the target material.

[0118] (Heating roller 31)

[0119] The heating roller 31 (heating unit) is a component that heats the positive electrode active material 1 through heat conduction. "Heating the positive electrode active material 1 through heat conduction" refers to so-called contact heating. Furthermore, the heating roller 31 heats the positive electrode active material 1 through the transport member 11. Therefore, the heat from the heating roller 31 is conducted to the transport member 11 and then to the positive electrode active material 1, thus heating the positive electrode active material 1. Alternatively, the heating roller 31 can be in contact with the positive electrode active material 1 through other components besides the transport member 11 to heat the positive electrode active material 1.

[0120] The heating roller 31 heats the positive electrode active material 1 through contact heating, characterized by efficient heating of the contact area and high heat uniformity. Therefore, the firing time of the positive electrode active material 1 can be reduced, and crystallinity deviations can be suppressed. Furthermore, due to the high heat uniformity of contact heating, although conventional manufacturing of positive electrode active materials requires two heating processes—pre-firing and firing—the manufacturing apparatus 100 can obtain the positive electrode active material by firing the material in a single process. Therefore, the manufacturing apparatus 100 improves the productivity of manufacturing positive electrode active materials. Additionally, by shortening the heating time, the equipment can be miniaturized.

[0121] By using a heating roller 31 as a heating unit, the positive electrode active material 1 can be heated while being transported, thus enabling continuous production of the positive electrode active material 2.

[0122] like Figure 1 As described, the heating unit 30 includes six heating rollers 31. The arrangement and number of the heating rollers 31 are not particularly limited, but... Figure 1 As described, heating rollers for heating one side (e.g., the top) and the other side (e.g., the bottom) of the positive electrode active material 1 can be alternately arranged from upstream to downstream in the transport direction. This allows for uniform heating of both sides of the positive electrode active material 1, thereby reducing temperature unevenness.

[0123] Furthermore, adjacent heating rollers 31 can be arranged facing each other to clamp the positive electrode active material 1. This allows for simultaneous heating of both sides of the positive electrode active material 1, thereby improving heating efficiency and reducing temperature unevenness. Additionally, by arranging adjacent heating rollers 31 facing each other, pressure can be applied and the positive electrode active material 1 heated. That is, the positive electrode active material 1 can be heated and formed into a sheet. The thickness of the sheet-like positive electrode active material 1 can be adjusted by adjusting the gap between the facing heating rollers 31. For example, the gap between the facing heating rollers 31 can be gradually narrowed from the upstream side to the downstream side in the transport direction. This allows the heating rollers 31 to be arranged to reliably clamp the positive electrode active material 1, thus reducing temperature unevenness. Moreover, since the heating rollers 31 are not intended for forming the positive electrode active material 1, the gap between the heating rollers 31 can be adjusted less strictly.

[0124] exist Figure 1 In this configuration, adjacent heating rollers are arranged facing each other. Figure 1 It can be seen that wrap angles are set for the heating rollers 31 excluding the upstream and downstream heating rollers 31. Figure 7 The diagram shown illustrates the corner of the enclosure. Additionally, in Figure 3 The middle shows Figure 8 Enlarged view of heating roller 31.

[0125] The term "corner wrapping" refers to... Figure 7 , Figure 8 The center angle of the heating roller 31, indicated by "x", is determined based on the range from the point of contact between the positive electrode active material 1 (conveyor member 11) and the heating roller 31 until its separation. This is achieved through... Figure 7 By setting the wrap angle x of the heating roller 31 as shown, the contact area between the heating roller 31 and the positive electrode active material 1 can be increased, thereby improving the heating efficiency. Furthermore, since the positive electrode active material 1 can be moved by smoothing it, heating unevenness can be reduced, and gas exchange can be promoted. Adhesion of the positive electrode active material 1 to the heating roller 31 can also be suppressed. Moreover, the positive electrode active material 1 sandwiched between the opposing heating rollers 31 is fired by being heated from both sides; on the other hand, the positive electrode active material 1, although not sandwiched between heating rollers 31 but in contact with one heating roller 31, can be heated on the contact surface while gas exchange occurs on the open surface that has not been in contact with the heating roller 31, thus promoting the firing of the positive electrode active material 1. Therefore, by using the method shown... Figure 1 , Figure 8 The heating roller 31 is configured as shown, which can alternately heat both sides of the positive electrode active material 1 (heat forming) and heat one side of the positive electrode active material 1, thereby alternating heating and efficient gas exchange to promote firing.

[0126] The wrap angle x of the heating roller 31 is not particularly limited, but if it is Figure 1 The configuration can be set to 10° or more, 20° or more, 180° or less, or 90° or less. If the wrap angle of the heating roller is less than 10°, it becomes difficult to smooth and move the positive electrode active material 1. On the other hand, there is no disadvantage caused by the wrap angle of the heating roller 31 exceeding 180°. If the wrap angle of the heating roller 31 exceeds 180°, there is a concern that the positive electrode active material 1 may easily slip off the end of the transport member 11 near the vertical direction of the heating roller 31, but such slippage can be suppressed by the positive electrode active material holding part of the transport member 11. However, if it is Figure 1 From a structural perspective, it is preferable to set the wrap angle of the heating roller 31 to be less than 180°. The configuration of the heating roller 31 with a wrap angle exceeding 180° will be explained in the second embodiment described later.

[0127] exist Figure 8In this configuration, the heating rollers 31 are arranged such that one of the straight lines connecting the centers of adjacent heating rollers 31 coincides with one of the straight lines forming the wrap angle. This ensures that the positive electrode active material 1 is always in contact with the heating rollers 31, thereby improving heating efficiency and shortening heating time.

[0128] Furthermore, in Figure 8 In this design, a wrap angle is set for the heating rollers 31 other than the upstream and downstream heating rollers 31, but the wrap angle can also be set for the upstream and downstream heating rollers 31. For example, the wrap angle can be set to a desired value for the upstream and downstream heating rollers 31 by using a contact roller.

[0129] The material of the heating roller 31 is not particularly limited. For example, the heating roller 31 can be made of a material with heat resistance of 1000°C or higher. Examples of such materials include inorganic materials such as ceramics and metallic materials such as iron.

[0130] The heating roller 31 can rotate in either a forward (same as the conveying direction) or a reverse (opposite to the conveying direction). The rotational speed of the heating roller 31 is not particularly limited. Those skilled in the art can appropriately select the most suitable rotational direction and speed that balances heat distribution and economy.

[0131] The surface of the heating roller 31 can also be uneven. By having an uneven surface, the positive electrode active material 1 in contact with the heating roller 31 can be moved, reducing uneven heating and promoting gas exchange. Furthermore, it can also suppress the adhesion of the positive electrode active material 1 to the heating roller. Furthermore, as... Figure 6 As shown, in order to suppress the slippage of the positive electrode active material 1, the heating roller 31 may also have a specified protrusion 31d.

[0132] The length of the heating roller 31 in the width direction is not particularly limited, but can be set to, for example, the same length as the length of the conveying member 11 in the width direction. The diameter of the heating roller 31 is appropriately set from the viewpoint of the size of the heating section 30 and the proper heating of the positive electrode active material 1.

[0133] <Recycling Department 40>

[0134] The recovery unit 40 is a component that recovers the positive electrode active material 2 obtained through the heating unit 30. For example... Figure 1As shown, when the positive electrode active material 2 is transported by clamping it with the transport member 11, the positive electrode active material 2 inside can be recovered by separating the transport member 11 in the recovery section 40. For this separation of the transport member 11, a predetermined roller 41 can be appropriately configured. Furthermore, the recovered positive electrode active material 2 can also be crushed. The crushing method for the positive electrode active material 2 is not particularly limited; the positive electrode active material 2 can be crushed using a hammer or the like after recovery. Additionally, when the positive electrode active material 1 is in sheet form, since the obtained positive electrode active material 2 is also in sheet form, it can be easily crushed. For example, as... Figure 1 As shown, the process involves simply recycling the positive electrode active material 2 to break it down.

[0135] When a porous heat-resistant component is used for the transport component 11, sometimes a positive electrode active material 2 is embedded in the internal pores. In such cases, by applying vibration while the transport component 11 is flipped over, air is sprayed onto the surface that has never been in contact with the positive electrode active material 2. Figure 1 Devices such as (arrows) can recover the positive electrode active material 2 buried inside, thereby improving productivity. Examples of devices that apply vibration include, for example, a vibration knocker. Examples of devices that blow air include, for example, a blower.

[0136] <Positive Electrode Active Material 2>

[0137] The positive electrode active material 2 obtained using the manufacturing apparatus 100 has a composition in which lithium is intercalated into a metal oxide. For example, the molar ratio of each metal element in the positive electrode active material 2 can be Li:Ni:Co:Mn = s:x:y:z (0.8 ≤ s ≤ 1.2, x = 1 - y - z, 0 ≤ y < 1, 0 ≤ z < 1), or it can be Li:Ni:Co:Al = s:x:y:z (0.8 ≤ s ≤ 1.2, x = 1 - y - z, 0 ≤ y < 1, 0 ≤ z < 1). Alternatively, the composition of the positive electrode active material 2 can be Li... s Ni x Co y Mn z (O) 2+α (0.8≤s≤1.2, x=1-y-z, 0≤y<1, 0≤z<1,-0.5≤α<0.5), could be Li s Ni x Co y Al z (O) 2+α (0.8≤s≤1.2, x=1-y-z, 0≤y<1, 0≤z<1, -0.5≤α<0.5).

[0138] Furthermore, since the positive electrode active material 1 is sintered through contact heating, deviations in the crystallinity of the resulting positive electrode active material 2 are suppressed. The crystallinity deviation is determined by XRD-based crystallite size measurement, and an optimal crystallite size (in nm) range is set to match the battery evaluation results of the positive electrode active material 2. For example, the crystallite size deviation range can be approximately ±200 nm, ±100 nm, or ±50 nm.

[0139] [Second Implementation]

[0140] Next, the second embodiment will be described. Figure 9 A schematic diagram of a manufacturing apparatus 200 (sometimes referred to as "manufacturing apparatus 200" in this specification) for manufacturing positive electrode active material for lithium-ion secondary batteries according to the second embodiment is shown. Manufacturing apparatus 200 is obtained by replacing the heating section 30 of manufacturing apparatus 100 with a heating section 130. Specifically, the wrap angle x of the heating roller 31 is changed to exceed 180°. The configuration other than the heating section 130 is the same as that of manufacturing apparatus 100.

[0141] like Figure 9 As shown, heating section 130, like heating section 30, includes six heating rollers 131. Furthermore, compared to the heating rollers 31 of heating section 30, the wrap angle x of heating rollers 131 is larger. Specifically, the wrap angle x of heating rollers 131 exceeds 180° and is less than 360°. Figure 10 A diagram illustrating the wrap angle x of the heating roller 131 is shown. The explanation of the wrap angle x is omitted here as it has already been described previously.

[0142] By setting the wrap angle x of the heating roller 131 to more than 180°, the positive electrode active material 1 is transported in the height direction. This promotes the rolling of the positive electrode active material 1 during transport, improves heat uniformity, and facilitates gas exchange. Consequently, uneven oxidation of the positive electrode active material 2 as a product is suppressed, and its quality is improved. Furthermore, since the contact time between the heating roller 31 and the positive electrode active material 1 can be extended, miniaturization of the equipment is possible.

[0143] By setting the wrap angle x of the heating roller 131 to be greater than 180°, compared to the case where the wrap angle x is less than 180°, a strong tension is applied to the transport member 11 when transporting the positive electrode active material 1 in the height direction. The positive electrode active material 1 inside the transport member 11 is subjected to load in the vertical direction, raising concerns about slippage from the end. However, since the transport member 11 has a defined positive electrode active material holding portion, such slippage can be suppressed. The wrap angle x of the heating roller 131 can be set to 210° or more, 240° or more, 270° or more, 300° or more, less than 360°, less than 350°, or less than 330°.

[0144] Furthermore, the heating section 130, unlike the heating section 30, includes a contact roller 132. The contact roller 132 is used to set the wrap angle of the adjacent heating roller 131. The contact roller 132 can be positioned facing the adjacent heating roller 31. Figure 9 In the manufacturing apparatus 200, contact rollers 132 are provided at positions adjacent to the heating rollers 131 on the upstream and downstream sides in the conveying direction, respectively. Furthermore, in the manufacturing apparatus 200, the contact rollers 132 are arbitrary components. Additionally, the number of contact rollers 132 can be at least one. Moreover, the position of the contact rollers 132 is not particularly limited, as long as they are positioned adjacent to the heating rollers 131 at a set wrap angle x.

[0145] The material of the contact roller 32 is not particularly limited. For example, it can be appropriately selected from the material of the heating roller 131. The length of the contact roller 132 in the width direction is not particularly limited, but it can be set to be the same as the length of the conveying member 11 in the width direction. The diameter of the contact roller 132 can be appropriately set based on the size of the heating section 130 and the wrap angle of the heating roller 131.

[0146] The wrap angle x can be set according to the configuration of the heating roller 131 and the contact roller 132. Figure 11 An enlarged view of the heating roller 131 and the contact roller 132 is shown. Figure 11 In this configuration, adjacent heating rollers 31 are arranged facing each other such that their wrap angle x is a predetermined value. This arrangement allows the wrap angle x of the heating rollers 131, except for the upstream and downstream heating rollers 131, to be set to a desired value. Furthermore, in the transport direction, contact rollers 132 are arranged adjacent to the upstream and downstream heating rollers 131. This allows the wrap angle of the upstream and downstream heating rollers 131 to be set to a desired value. Furthermore, as... Figure 11 As shown, the heating rollers 131 are respectively configured such that the straight line connecting the centers of adjacent heating rollers 131 coincides with one of the straight lines forming the wrap angle. This ensures that the positive electrode active material 1 is always in contact with the heating rollers 131, thereby improving heating efficiency and shortening heating time.

[0147] [Third Implementation Method]

[0148] Next, the third embodiment will be described. Figure 12 This diagram shows a manufacturing apparatus 300 (sometimes referred to as "manufacturing apparatus 300" in this specification) for manufacturing positive electrode active material for lithium-ion secondary batteries according to a third embodiment. Manufacturing apparatus 300 is obtained by replacing the heating section 30 of manufacturing apparatus 100 with a heating section 230. Specifically, the heating roller 31 is replaced with a plate-shaped heating unit 231. The configuration other than the heating section 230 is the same as that of manufacturing apparatus 100.

[0149] The plate-shaped heating unit 231 is a plate-shaped heating unit, such as... Figure 12 As described, the plate-shaped heating units 231, arranged in pairs, are arranged in three rows in the transport direction. Furthermore, the positive electrode active material 1 (transport member 11) is clamped and heated by raising and lowering the plate-shaped heating units 231. Pressure forming can also be performed at this time. Moreover, the transport member 11 can be temporarily stopped during heating. Even using the plate-shaped heating units 131 as heating units in this way, contact heating can be achieved.

[0150] The plate heating unit 231 can be made of the same material as the heating roller 31. In addition, the size and area of ​​the plate heating unit 231 can be appropriately set.

[0151] [Replenish]

[0152] In manufacturing apparatuses 100, 200, and 300, multiple heating units (heating rollers, plate-shaped elastic members) are used; however, the manufacturing apparatus of this disclosure is not limited to this, and only one heating unit is required. This is because only the number required for sintering the positive electrode active material 1 is needed. Furthermore, the shape of the heating unit is not limited to roller or plate shape; various shapes of heating units can be used. This is because any shape capable of achieving contact heating is acceptable. Additionally, according to the first and second embodiments, the wrap angle x of the heating roller is not limited and can be appropriately selected from a range of 0° to 360°.

[0153] 2. Manufacturing method of positive electrode active material for lithium-ion secondary batteries

[0154] The method for manufacturing the positive electrode active material for lithium-ion secondary batteries disclosed herein will be described with reference to the following first to third embodiments.

[0155] [First Implementation Method]

[0156] The method for manufacturing the positive electrode active material for lithium-ion secondary batteries disclosed herein will be described with reference to the method for manufacturing the positive electrode active material for lithium-ion secondary batteries according to the first embodiment (sometimes referred to as "manufacturing method 1000" in this specification).

[0157] Figure 13 A flowchart illustrating a method for manufacturing the positive electrode active material for a lithium-ion secondary battery according to the first embodiment (sometimes referred to in this specification as "manufacturing method 1000"). Figure 13 As shown, the manufacturing method 1000 includes a positive electrode active material preparation step S1, a forming step S2, a heating step S3, and a recycling step S4. Furthermore, the forming step S2, the heating step S3, and the recycling step S4 can be performed using the manufacturing apparatus disclosed herein.

[0158] <Cathode Active Material Fabrication Process S1>

[0159] Step S1, the process for producing the positive electrode active material, involves mixing a metal compound and a lithium compound to obtain the positive electrode active material. The metal compound, lithium compound, and positive electrode active material have been described previously and are therefore omitted here. Furthermore, the mixing method has also been described previously and is therefore omitted here.

[0160] <Forming process S2>

[0161] The forming process S2 is arbitrary and is performed before the heating process S3. The forming process S2 is the process of forming the positive electrode active material into a sheet shape. The method for forming the positive electrode active material into a sheet shape is not particularly limited. For example, the forming method described above can be used.

[0162] <Heating process S3>

[0163] Heating step S3 is a process of heating (firing) the positive electrode active material. Specifically, heating step S3 is a process of heating the positive electrode active material through heat conduction. The method of heating the positive electrode active material has been described above, so it will not be explained here.

[0164] <Recycling Process S4>

[0165] Recovery step S4 is a step to recover the positive electrode active material obtained through heating step S3. The method for recovering the positive electrode active material is not particularly limited. For example, the recovery method described above can be used.

[0166] [Second Implementation]

[0167] Next, the second embodiment will be described. Figure 14A method 2000 for manufacturing a positive electrode active material for a lithium-ion secondary battery (sometimes referred to as "manufacturing method 2000" in this specification) is shown according to a second embodiment. Manufacturing method 2000 is a manufacturing method obtained by adding an oxidation calcination step S5 to manufacturing method 1000. The oxidation calcination step S5 is a step performed before the positive electrode active material preparation step S1, in which a metal hydroxide is heated in an oxidizing atmosphere. The oxidation calcination method for the metal hydroxide has been described previously and is therefore omitted here. By providing the oxidation calcination step S5, a metal oxide can be obtained. Since the oxidation of metal hydroxide is an endothermic reaction, there is a concern that temperature unevenness may occur if a positive electrode active material containing metal hydroxide is used in the heating step S3. Therefore, in manufacturing method 2000, the oxidation calcination step S5 is provided to pre-oxidize the metal hydroxide. However, since contact heating is used in the heating step S3, temperature unevenness can be reduced even when using a positive electrode active material containing metal hydroxide.

[0168] [Third Implementation Method]

[0169] Next, the third embodiment will be described. Figure 15 The present invention illustrates a method 3000 for manufacturing a positive electrode active material for a lithium-ion secondary battery (sometimes referred to as "manufacturing method 3000" in this specification). Manufacturing method 3000 is a method in which a pre-firing step S6 is performed before the forming step S2. The pre-firing step S6 is a step in which the positive electrode active material material is heated in an oxidizing atmosphere. Through the pre-firing step S6, metal hydroxides can be oxidized to metal oxides, and lithium compounds such as lithium hydroxides can be oxidized to lithium oxide. Since such an oxidation reaction is endothermic, by utilizing the pre-firing step S6 to complete the oxidation of the positive electrode active material material, temperature unevenness of the positive electrode active material material can be reduced in the heating step S3, and firing can be performed in a short time. However, since contact heating is used in the heating step S3, even without the pre-firing step S6, the positive electrode active material material containing metal hydroxides, etc., can be appropriately fired to obtain the positive electrode active material.

[0170] The heating temperature for the pre-firing process S6 is, for example, 700°C to 800°C. The heating time is, for example, 0.5 hours to 3 hours. Such heating can be carried out using a firing apparatus such as a rotary kiln.

[0171] [Replenish]

[0172] In the manufacturing method disclosed herein, the oxidation roasting process and the pre-calcination process can also be combined.

[0173] 3. Effects

[0174] The apparatus and method for manufacturing positive electrode active material for lithium-ion secondary batteries disclosed herein have been described above using various embodiments. This disclosure employs contact heating, where the positive electrode active material material is heated by heat conduction. Contact heating is characterized by efficient heating of the contact area and low temperature uniformity (high heat homogeneity) at the contact area. Therefore, this disclosure, employing contact heating, can reduce the firing time of the positive electrode active material material and suppress crystallinity deviations. Furthermore, unlike conventional methods, this disclosure allows for firing of the positive electrode active material material using a single heating section (heating process) to obtain the positive electrode active material. Therefore, according to this disclosure, the productivity of manufacturing positive electrode active materials can be improved. Additionally, by shortening the heating time, the equipment can be miniaturized.

[0175] Furthermore, this disclosure provides a defined positive electrode active material holding portion at the end of the transport component, thereby preventing the positive electrode active material 1 from slipping off. Therefore, according to this disclosure, the manufacturing productivity of the positive electrode active material 2 can be further improved.

[0176] Example

[0177] The following examples further illustrate this disclosure.

[0178] according to Figure 9 A manufacturing apparatus was prepared. A mixture of nickel cobalt manganese oxide and lithium carbonate was prepared as the positive electrode active material. The positive electrode active material was then placed on a transport member and heated using a heating element to produce the positive electrode active material. At this time, the temperature of the heating rollers was set to 950°–1000°. Furthermore, the wrap angle of all the heating rollers was set to exceed 180°.

[0179] Here, in the embodiment, a method using the following is employed. Figure 3 A transport member for holding positive electrode active material is formed by bending the end multiple times. In the comparative example, a transport member without a positive electrode active material holding portion was used.

[0180] Based on the above, the positive electrode active material was manufactured five times under the conditions of the examples and comparative examples, and the recovery rate of the positive electrode active material was evaluated. The recovery rate of the positive electrode active material was calculated by setting the weight of the positive electrode active material that was completely converted into positive electrode active material and recovered to 100%. As a result, in the comparative examples, the recovery rate of the positive electrode active material was about 58% to 67%, but in the examples, the recovery rate was 98% to 100%. It is believed that this difference in results is due to the fact that the positive electrode active material holding part suppressed the slippage of the positive electrode active material.

[0181] Industrial availability

[0182] The positive electrode active material manufactured according to this disclosure can be used in the positive electrode of any battery, including non-aqueous lithium-ion secondary batteries, aqueous lithium-ion secondary batteries, and all-solid-state lithium-ion secondary batteries.

Claims

1. An apparatus for manufacturing positive electrode active material for lithium-ion secondary batteries, comprising a forming unit, a conveying unit, and a heating unit. The forming unit, located upstream of the heating section in the transport direction, forms the positive electrode active material into a sheet with a thickness of 0.1 mm or more and 50 mm or less. The delivery unit delivers a positive electrode active material, which comprises a lithium compound and a metal compound, wherein the metal compound comprises at least one metal element selected from nickel, cobalt, and manganese. The heating element heats the positive electrode active material. The heating section has at least one heating unit, which heats the positive electrode active material through heat conduction. The heating unit comprises multiple heating rollers, with heating rollers that heat one side of the positive electrode active material and heating rollers that heat the other side of the positive electrode active material alternately arranged from the upstream side to the downstream side in the transport direction. Adjacent heating rollers are arranged facing each other in a manner that clamps the positive electrode active material between them. The wrap angle of the heating rollers is 210° or more and 360° or less. The transport unit has a transport component for transporting the positive electrode active material. The heating unit heats the positive electrode active material via the transport component. The transport member has a positive electrode active material holding part at its end in the width direction. A conveying member is disposed on both sides of the positive electrode active material, so that the positive electrode active material is conveyed in a state of being clamped by the conveying member. The positive electrode active material holding portion is formed by narrowing at the end of the conveying member. The heating roller forms a recess by having a protrusion at the end corresponding to the positive electrode active material holding portion, so that the positive electrode active material is heated inside the recess. The total thickness of the protrusion at a single end is more than 110% and less than 200% of the thickness of the positive electrode active material.

2. The manufacturing apparatus according to claim 1, The heating section heats the positive electrode active material to a temperature above 700°C and below 1000°C.

3. The manufacturing apparatus according to claim 1 or 2, The heating element heats the positive electrode active material in an oxidizing atmosphere.

4. The manufacturing apparatus according to claim 1 or 2, The transport component is made of a porous, heat-resistant material.

5. The manufacturing apparatus according to claim 1 or 2, It has a recovery unit that recovers the positive electrode active material obtained through the heating unit.

6. A method for manufacturing a positive electrode active material for lithium-ion secondary batteries, comprising: The process for manufacturing positive electrode active material involves mixing a lithium compound with a metal compound to obtain a positive electrode active material, wherein the metal compound contains at least one metal element selected from nickel, cobalt, and manganese. In the forming process, before heating, the positive electrode active material is formed into a sheet with a thickness of 0.1 mm or more and 50 mm or less; and The heating process involves heating the positive electrode active material. In the heating process, the positive electrode active material is heated by heat conduction. In the heating process, the positive electrode active material is transported by a conveying member, and the positive electrode active material is heated through the conveying member. In the heating process, multiple heating rollers with a wrap angle of 210° or more and 360° or less, arranged facing each other to clamp the positive electrode active material, are used to alternately heat both sides of the positive electrode active material and one side of the positive electrode active material, while the positive electrode active material is being transported and heated simultaneously. The transport member has a positive electrode active material holding part at its end in the width direction. A conveying member is disposed on both sides of the positive electrode active material, so that the positive electrode active material is conveyed in a state of being clamped by the conveying member. The positive electrode active material holding portion is formed by narrowing at the end of the conveying member. The heating roller forms a recess by having a protrusion at the end corresponding to the positive electrode active material holding portion, so that the positive electrode active material is heated inside the recess. The total thickness of the protrusion at a single end is more than 110% and less than 200% of the thickness of the positive electrode active material.

7. The manufacturing method according to claim 6, In the heating process, the positive electrode active material is heated to above 700°C and below 1000°C.

8. The manufacturing method according to claim 6 or 7, In the heating process, the positive electrode active material is heated in an oxidizing atmosphere.

9. The manufacturing method according to claim 6 or 7, The transport component is made of a porous, heat-resistant material.

10. The manufacturing method according to claim 6 or 7, It has a recovery process for recovering the positive electrode active material obtained through the heating process.

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