Apparatus and method for manufacturing positive electrode active material for lithium ion secondary battery

Abstract

To provide a manufacturing device for a positive electrode active substance for a lithium-ion secondary battery that can improve productivity.SOLUTION: A manufacturing device 100 for a positive electrode active substance 2 for a lithium-ion battery includes conveying means 10 for conveying a positive electrode active substance material 1 containing a metal compound containing at least one metal element selected from the group consisting of nickel, cobalt, and manganese and a lithium compound and a heating unit 30 for heating the positive electrode active substance material 1. The heating unit 30 has at least one piece of heating means 31 that heats the positive electrode active substance material 1 by thermal conduction. The conveying means 10 has a conveying member 11 for conveying the positive electrode active substance. The heating means 31 heats the positive electrode active substance material 1 via the conveying member 11. The conveying member 11 has a positive electrode active substance material holding portion at the edge in the width direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present application relates to an apparatus and method for producing a positive electrode active material for a lithium ion secondary battery. [Background technology]

[0002] Lithium ion secondary batteries are widely used as power sources for laptop computers, mobile terminals, etc., and for driving vehicles, etc. Therefore, there is a demand for improving the productivity of lithium secondary batteries, and there is also a demand for improving the productivity of positive electrode active materials used in lithium secondary batteries.

[0003] A typical method for manufacturing a positive electrode active material for a lithium ion secondary battery is as follows. First, a metal hydroxide containing nickel or the like as a precursor and a lithium compound (for example, lithium hydroxide or lithium carbonate) are mixed to obtain a positive electrode active material. Next, the positive electrode active material is calcined to oxidize the positive electrode active material. Specifically, the metal hydroxide is oxidized to a metal oxide, and the lithium compound is oxidized to lithium oxide. Next, the calcined positive electrode active material is filled into a predetermined sagger and fired. The firing causes a reaction between the metal oxide in the positive electrode active material and the lithium oxide, and lithium metal oxide, which is a positive electrode active material, is obtained. The obtained positive electrode active material is then collected and used in a lithium ion secondary battery. Such a method for manufacturing a positive electrode active material is disclosed in, for example, Patent Documents 1 to 3.

[0004] In the step of calcining the positive electrode active material, a calcination device such as a rotary kiln is used. The rotary kiln is a device that can heat the positive electrode active material while stirring it in an oxidizing atmosphere, and can promote the oxidation of the positive electrode active material. The reason for calcining the positive electrode active material is to prevent temperature unevenness in the positive electrode active material caused by the endothermic reaction during the calcination step, since the oxidation reaction of the metal hydroxide and the lithium compound is an endothermic reaction.

[0005] In the process of firing the positive electrode active material, a firing device 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 calcination process, and the positive electrode active material can be produced by reacting the metal oxide in the positive electrode active material with lithium oxide. In addition, when the positive electrode active material is filled into a sagger, pressure may be applied to densify the material. Densifying the positive electrode active material increases the contact area between the metal oxide in the positive electrode active material and lithium oxide, facilitating firing. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-113429 A [Patent Document 2] JP 2019-175694 A [Patent Document 3] JP 2020-198195 A Summary of the Invention [Problem to be solved by the invention]

[0007] Since the rotary kiln is a device for oxidizing metal hydroxides and / or lithium compounds, it is necessary to actively feed air or oxygen into the rotary kiln to create an oxidizing atmosphere. However, since it is necessary to actively feed air or oxygen into the rotary kiln, production costs increase.

[0008] The roller hearth kiln is a device for firing the calcined positive electrode active material, and the positive electrode active material needs to be filled into a sagger in order to heat it uniformly. However, the flow of hot air in the device tends to cause temperature unevenness in the positive electrode active material. If the positive electrode active material is heated for a short time in a state in which temperature unevenness occurs in the positive electrode active material, the crystallinity of the produced positive electrode active material will vary. Therefore, when producing a positive electrode active material using a roller hearth kiln, it is necessary to heat the positive electrode active material for a long time in order to suppress temperature unevenness, but this increases production costs. In addition, since heating is required for a long time, the equipment tends to become large.

[0009] Therefore, an object of the present application is to provide an apparatus and method for manufacturing a positive electrode active material for a lithium ion secondary battery, which can improve productivity. [Means for solving the problem]

[0010] As one aspect for solving the above-mentioned problems, the present disclosure provides an apparatus for manufacturing a positive electrode active material for a lithium ion secondary battery, comprising: a conveying means for conveying a positive electrode active material containing a lithium compound and a metal compound containing at least one metal element selected from the group consisting of nickel, cobalt, and manganese; and a heating unit for heating the positive electrode active material, wherein the heating unit has at least one heating means for heating the positive electrode active material by thermal conduction, the conveying means has a conveying member for conveying the positive electrode active material, the heating means heats the positive electrode active material via the conveying member, and the conveying member has a positive electrode active material holding unit at an end in the width direction.

[0011] In the above manufacturing apparatus, the heating means may be a heating roller. In addition, in the above manufacturing apparatus, the heating means may be a plurality of heating rollers, and the heating rollers for heating one side of the positive electrode active material and the heating rollers for heating the other side of the positive electrode active material are alternately arranged from the upstream side to the downstream side in the conveying direction, and the adjacent heating rollers are arranged opposite to each other so as to sandwich the positive electrode active material. Furthermore, the wrap angle of the heating rollers may be more than 180° and 360° or less.

[0012] In the above-mentioned manufacturing apparatus, the heating section may heat the positive electrode active material to 700° C. or more and 1000° C. or less. The heating section may heat the positive electrode active material in an oxidizing atmosphere.

[0013] In the above-mentioned manufacturing apparatus, the conveying member may be made of a porous heat-resistant member.

[0014] The manufacturing apparatus may further include a forming unit for forming the positive electrode active material into a sheet upstream of the heating unit in the conveying direction. The manufacturing apparatus may further include a recovery unit for recovering the positive electrode active material obtained by the heating unit.

[0015] As one aspect for solving the above-mentioned problems, the present disclosure provides a method for producing a positive electrode active material for a lithium ion secondary battery, the method comprising: a positive electrode active material preparation step of mixing a metal compound containing at least one metal element selected from the group consisting of nickel, cobalt, and manganese with a lithium compound to obtain a positive electrode active material; and a heating step of heating the positive electrode active material, the heating step heating the positive electrode active material by thermal conduction, the positive electrode active material being transported by a transport member and heated via the transport member in the heating step, the transport member having a positive electrode active material holding portion at an end in the width direction.

[0016] In the above manufacturing method, the heating step may heat the positive electrode active material while conveying it. In addition, in the above manufacturing method, the heating step may alternately heat both sides of the positive electrode active material and one side of the positive electrode active material. Furthermore, in the heating step of the above manufacturing method, the positive electrode active material may be heated using a heating roller having a wrap angle of more than 180° and not more than 360°.

[0017] In the above manufacturing method, the heating step may heat the positive electrode active material to 700° C. or more and 1000° C. or less. In the above manufacturing method, the heating step may heat the positive electrode active material in an oxidizing atmosphere.

[0018] In the above manufacturing method, the conveying member may be made of a porous heat-resistant member.

[0019] The above-mentioned manufacturing method may include a forming step of forming the positive electrode active material into a sheet prior to the heating step. Also, the above-mentioned manufacturing method may include a recovery step of recovering the positive electrode active material obtained by the heating step. Effect of the Invention

[0020] According to the present disclosure, it is possible to improve the production productivity of the positive electrode active material. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic diagram of an apparatus 100 for producing a positive electrode active material for a lithium ion secondary battery. [Diagram 2] 1 is a widthwise cross-sectional view showing how the positive electrode active material 1 slides down from an end of a conveying member 11. FIG. [Diagram 3] 3 is a cross-sectional view in the width direction of a conveying member 11 having a positive electrode active material holding portion 12a. FIG. [Figure 4] 1 is a cross-sectional view in the width direction of a conveying member 11 having a positive electrode active material holding portion 12b. [Diagram 5] 1 is a cross-sectional view in the width direction of a conveying member 11 having a positive electrode active material holding portion 12c. [Figure 6] FIG. 2 is a cross-sectional view in the width direction of a conveying member 11 having a positive electrode active material holding portion 12d. [Figure 7] 4 is a diagram for explaining the embrace angle x of the heating roller 31. FIG. [Figure 8] FIG. [Figure 9] FIG. 2 is a schematic diagram of a manufacturing apparatus 200 for a positive electrode active material for a lithium ion secondary battery. [Figure 10] 13 is a diagram for explaining a embrace angle x of a heating roller 131. FIG. [Figure 11] 2 is an enlarged view of a heating roller 131 and a touch roll 132. FIG. [Figure 12]FIG. 3 is a schematic diagram of a manufacturing apparatus 300 for a positive electrode active material for a lithium ion secondary battery. [Figure 13] 1 is a flowchart of a method 1000 for producing a positive electrode active material for a lithium ion secondary battery. [Figure 14] 2 is a flowchart of a method 2000 for producing a positive electrode active material for a lithium ion secondary battery. [Figure 15] 3 is a flowchart of a method 3000 for producing a positive electrode active material for a lithium ion secondary battery. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] 1. Manufacturing equipment for positive electrode active materials for lithium-ion secondary batteries The manufacturing apparatus for a positive electrode active material for a lithium ion secondary battery according to the present disclosure will be described with reference to the following first to third embodiments.

[0023] [First embodiment] A schematic diagram of a manufacturing apparatus 100 for manufacturing a positive electrode active material for a lithium ion secondary battery according to a first embodiment (sometimes referred to as "manufacturing apparatus 100" in this specification) is shown in Fig. 1. Here, the left-right direction in Fig. 1 is the conveying direction, the up-down direction is the height direction, and the back-to-front direction is the width direction.

[0024] 1, the manufacturing apparatus 100 includes a conveying means 10, a forming means 20, a heating section 30, and a recovery section 40. Also shown in Fig. 1 are a cathode active material 1, which is a raw material, and a cathode active material 2, which is a product.

[0025] <Cathode active material 1> The positive electrode active material 1 contains a metal compound and a lithium compound. It may also contain a positive electrode active material 2 that has already deteriorated and is broken into pieces, such as recycled materials. Even if the positive electrode active material 2 contains deteriorated positive electrode active material 2, it can be fired in the heating unit 30 with high thermal uniformity.

[0026] The positive electrode active material 1 can be obtained by mixing these materials. The mixing method is not particularly limited, and a known method can be used. For example, the materials can be mixed using a mortar or a blender.

[0027] (metal compound) The metal compound contains at least one metal element selected from the group consisting of nickel, cobalt, and manganese. The metal compound may contain nickel, nickel and cobalt, or nickel, cobalt, and manganese. It may further contain other metal elements. For example, the metal compound may further contain aluminum. The metal compound may also contain aluminum instead of manganese.

[0028] For example, the metal compound may have a molar ratio of each metal element such that Ni:Co:Mn=x:y:z (x=1-yz, 0≦y<1, 0≦z<1) or Ni:Co:Al=x:y:z (x=1-yz, 0≦y<1, 0≦z<1).

[0029] The metal compounds may be metal hydroxides, metal oxides, metal carbonates, and metal perhydroxides. These metal compounds may be used alone or in combination. Preferably, the metal compounds are metal hydroxides or metal oxides.

[0030] As the metal hydroxide, a known metal hydroxide containing at least one metal element selected from the group consisting of nickel, cobalt, and manganese can be used. For example, Ni x Co y Mn z (OH) 2+α (x=1-yz, 0≦y<1, 0≦z<1, 0≦α<1), and Ni x Co y Al z (OH) 2+α(x=1-yz, 0≦y<1, 0≦z<1, 0≦α<1). As the metal oxide, a known metal oxide containing at least one metal element selected from the group consisting of nickel, cobalt, and manganese can be used. For example, Ni x Co y Mn z (O) 2+α (x=1-yz, 0≦y<1, 0≦z<1, -1≦α<0), and Ni x Co y Al z (O) 2+α (x=1-yz, 0≦y<1, 0≦z<1, -1≦α<0).

[0031] The metal compounds can be prepared by known methods. Examples of methods for preparing metal hydroxides and metal oxides are shown below. However, the method for preparing the metal compounds is not limited to these.

[0032] For example, a crystallization method can be used to prepare a metal hydroxide. Hereinafter, an example of a method for preparing a metal hydroxide by the crystallization method will be described.

[0033] First, a Ni source, a Co source, and a Mn source (or an Al source) are dissolved in an aqueous solvent (e.g., ion-exchanged water) to prepare a metal source solution. As the metal source, each metal salt (i.e., Ni salt, Co salt, and Mn salt (or Al salt)) can be used. The type of metal salt is not particularly limited, and 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 may be prepared separately and mixed. The ratio of the metal sources is appropriately adjusted so that the desired metal hydroxide is obtained.

[0034] Next, the metal source solution and NH 3 The aqueous solution is dropped into an alkaline aqueous solution. The alkaline aqueous solution may be an aqueous sodium hydroxide solution or the like. The pH of the alkaline aqueous solution is set to, for example, 11 to 13. NH 3The aqueous solution is added dropwise while maintaining the concentration in the range of, for example, 5 g / L to 15 g / L. 3 By dropping the aqueous solution, the pH of the reaction solution gradually decreases, so that the pH may be maintained within a predetermined range by dropping an aqueous alkaline solution as needed.

[0035] After a certain period of time has passed, suction filtration is performed to recover the precipitate. The precipitate obtained is washed with water and dried to obtain a metal hydroxide. The precipitate may be washed with water multiple times. The precipitate may be dried by air drying or by heating. The heating drying may be performed at, for example, 120 to 300°C. The drying time is, for example, 6 to 18 hours.

[0036] The metal oxide can be produced, for example, by oxidizing roasting a metal hydroxide. Oxidizing roasting refers to heating a metal hydroxide in an oxidizing atmosphere. The heating temperature is not particularly limited as long as it can convert the metal hydroxide into a metal oxide, but is, for example, 700°C to 800°C. The heating time is not particularly limited as long as it can convert the metal hydroxide into a metal oxide, but is, for example, 0.5 hours to 3 hours. Such heating can be performed using a firing device such as a rotary kiln.

[0037] The average particle size of the metal compound is not particularly limited, but is, for example, in the range of 1 μm to 1 mm. In this specification, the term "average particle size" refers to the median particle size at an integrated value of 50% in a volume-based particle size distribution obtained by a laser diffraction / scattering method.

[0038] The content of the metal compound in the positive electrode active material is appropriately set so as to obtain a desired positive electrode active material.

[0039] (Lithium compounds) The lithium compound is not particularly limited as long as it is a compound containing lithium, and known lithium compounds can be used. For example, lithium oxide, lithium hydroxide, lithium nitrate, lithium carbonate, etc. Lithium hydroxide, lithium nitrate, lithium carbonate, etc. become lithium oxide by oxidation.

[0040] The type of lithium compound is appropriately selected according to the type of metal compound. This is because the heating temperature (calcination temperature) differs depending on the type of metal compound. For example, when a metal hydroxide or metal oxide containing nickel, cobalt, and manganese is used as the metal compound, a calcination temperature of about 800°C is required, so it is preferable to select lithium carbonate. Also, when a metal hydroxide or metal oxide containing nickel, cobalt, and aluminum is used as the metal compound, a calcination temperature of about 500°C is required, so it is preferable to select lithium hydroxide.

[0041] The content of the lithium compound in the positive electrode active material is appropriately set so as to obtain a desired positive electrode active material.

[0042] (Shape of positive electrode active material 1) The shape of the positive electrode active material 1 is not particularly limited, but may be in a sheet form. The positive electrode active material 1 being in a sheet form makes it easier to heat uniformly to the inside. As a result, uneven heating is reduced, and the variation in crystallinity of the positive electrode active material 2 produced is also suppressed. In addition, by making the positive electrode active material 1 in a sheet form, it can be easily crushed in the recovery section 40.

[0043] The thickness of the sheet-shaped positive electrode active material 1 is not particularly limited, and may be, for example, 0.1 mm or more, 0.5 mm or more, 1 mm or more, 2 mm or more, 50 mm or less, 30 mm or less, less than 30 mm, 20 mm or less, 10 mm or less, or 5 mm or less. If the sheet-shaped positive electrode active material 1 is too thick, it is difficult to heat uniformly, and if it is too thin, productivity decreases.

[0044] The positive electrode active material 1 may be formed into a sheet by the forming means 20 and / or the heating roller 31, or may be formed in advance into a sheet by press forming or the like. However, the positive electrode active material 1 may be formed into a sheet in advance, and then the positive electrode active material 1 may be formed into a predetermined thickness by the forming means 20 and / or the heating roller 31.

[0045] <Conveying means 10> The conveying means 10 is a member for conveying the positive electrode active material 1. As shown in Fig. 1, the conveying means 10 includes a conveying member 11 for conveying the positive electrode active material 1. The conveying means 10 also includes a driving means (not shown) for driving the conveying member 11.

[0046] (Transport member 11) The transport member 11 is a member (conveyor) that transports the positive electrode active material 1. The transport member 11 is a sheet-like member, and is driven by a driving means from the upstream side to the downstream side in the transport direction. Since the transport member 11 transports the positive electrode active material 1 while carrying it thereon, it needs to be disposed on the lower surface of the positive electrode active material 1. In addition, as shown in FIG. 1, the transport member 11 is also disposed on the upper surface of the positive electrode active material 1. That is, the positive electrode active material 1 is transported while being sandwiched between the transport members 11.

[0047] As described later, the manufacturing apparatus 100 heats the positive electrode active material 1 by contact heating. Therefore, the positive electrode active material 1 may be heated by directly contacting it with the heating roller 31, but this causes the positive electrode active material 1 to adhere to the heating roller 31, leading to a decrease in productivity. Therefore, in the manufacturing apparatus 100, the heating roller 31 is brought into contact with the positive electrode active material 1 via the conveying member 11, thereby preventing the positive electrode active material 1 from adhering to the heating roller 31. For this reason, the positive electrode active material 1 is conveyed by being sandwiched between the conveying members 11.

[0048] Since the conveying member 11 comes into contact with the heating roller 31, it needs to be made of a material (heat-resistant material) that is resistant to the heating temperature of the heating unit 30. For example, the heat-resistant material needs to have a heat resistance of 900° C. or higher. Examples of such heat-resistant materials include quartz glass cloth and silica fiber cloth.

[0049] Here, when the positive electrode active material 1 contains a material that becomes an oxide by oxidation, such as a metal hydroxide or lithium hydroxide, it is necessary to take in oxygen from the outside in order to proceed with the firing of the positive electrode active material 1. In addition, the positive electrode active material 1 may generate gases such as water (water vapor) and carbon dioxide by firing. Therefore, it is preferable that the positive electrode active material 1 is fired in an environment that allows gas exchange. Therefore, the conveying member 11 may be made of a porous heat-resistant member that allows efficient gas exchange with the outside. The pore size of the porous heat-resistant member is not particularly limited as long as it allows efficient gas exchange and does not leak the positive electrode active material 1 to the outside. For example, the pore size of the pores of the porous heat-resistant member may be 20 μm or less, 10 μm or less, 5 μm or less, 3 μm or more, 1 μm or more, or 0.5 μm or more. If the pore size of the porous heat-resistant member is too large, the positive electrode active material 1 is likely to leak to the outside, and if the pore size is too small, the efficiency of gas exchange with the outside is reduced. Examples of such porous heat-resistant members include fibrous heat-resistant members. For example, quartz glass cloth and silica fiber cloth are included.

[0050] Here, the pore size of the porous heat-resistant member is the length of the diagonal line of the mesh openings, which is calculated from the fiber diameter and the product density (unit: pieces / mm).

[0051] The conveying member 11 has a role of conveying the positive electrode active material 1, but the positive electrode active material 1 may slip off from the end of the conveying member 11 during conveyance. As described later, the manufacturing apparatus 100 uses the heating roller 31 to heat the positive electrode active material 1 by thermal conduction (contact heating). At this time, the positive electrode active material 1 in the conveying member 11 is subjected to a load in the vertical direction by being sandwiched between the opposing heating rollers 31. In addition, the positive electrode active material 1 in the conveying member 11 is subjected to a load in the vertical direction by being conveyed while contacting the heating roller 31 at a predetermined embrace angle, and a predetermined tension is applied to the positive electrode active material 1. In this case, the positive electrode active material 1 moves toward the outside in the width direction, and there is a problem that it slips off from the end of the conveying member 11. Furthermore, the lithium compound contained in the positive electrode active material 1, particularly lithium carbonate, has a low melting point and may melt and become a sol (liquefy) by heating. In this case, the positive electrode active material 1 becomes more likely to slip off.

[0052] Fig. 2 shows a widthwise cross-sectional view illustrating how the positive electrode active material 1 slides off from the end of the transport member 11. Fig. 2 corresponds to the AA cross section in Fig. 1. As shown in Fig. 2, the positive electrode active material 1 moves outward in the width direction due to the pressure from the heating roller 31, and slides off from the end of the transport member 11.

[0053] In order to prevent such a slippage, the conveying member 11 is provided with a positive electrode active material holding portion at the end in the width direction. The positive electrode active material holding portion may be provided at at least one of the ends in the width direction of the conveying member 11, but from the viewpoint of further preventing the positive electrode active material 1 from slipping down, it may be provided at both ends in the width direction of the conveying member 11. In addition, the positive electrode active material holding portion may be provided on either one of the conveying members 11 sandwiching the positive electrode active material 1, but from the viewpoint of further preventing the positive electrode active material 1 from slipping down, it may be provided on both conveying members 11. Specific embodiments of the positive electrode active material holding portions 12a to 12d are shown in Figs. 3 to 6, respectively. Figs. 3 to 6 correspond to the AA cross section of Fig. 1.

[0054] Fig. 3 is a widthwise cross-sectional view of a transport member 11 including a positive active material holding portion 12a. The positive active material holding portion 12a is formed by bending an end portion of the transport member 11. In Fig. 3, the positive active material holding portion 12a is formed by bending the ends of the transport member 11 arranged on the upper and lower surfaces of the positive active material 1, respectively.

[0055] The total thickness of the positive electrode active material holding portion 12a at one 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 total thickness of the positive electrode active material holding portion 12a at one end may 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 by the number of times the end of the conveying member 11 is folded. For example, the number of times the end of the conveying member 11 is folded may be at least once. In FIG. 3, each end is folded twice.

[0056] Since the conveying member 11 has the positive electrode active material holding portion 12a, the positive electrode active material 1 can be pushed back toward the inside in the width direction at the end portion, and the positive electrode active material 1 can be prevented from slipping off. In addition, since the density of the conveying member 11 at the end portion is high, pressure is more likely to be applied to the end portion than to the center in the width direction when the conveying member 11 comes into contact with the heating roller 31, and the movement of the positive electrode active material 1 toward the outside in the width direction is prevented, and the positive electrode active material 1 is further prevented from slipping off.

[0057] Fig. 4 is a cross-sectional view in the width direction of a transport member 11 including a positive active material holding portion 12b. The positive active material holding portion 12b is formed by weaving a heat-resistant material 13 into the end portion of the transport member 11. In Fig. 3, the positive active material holding portion 12b is formed by weaving a heat-resistant material 13b into the end portion of the transport member 11 arranged on the upper and lower surfaces of the positive active material 1. The heat-resistant material 13b is, for example, a string-like wire made of quartz glass or silica fiber, or a string-like wire made of bundled metal fibers.

[0058] The thickness of the positive electrode active material holding portion 12b at one 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 thickness of the positive electrode active material holding portion 12b at one end may be set to 110% or more and 200% or less of the thickness of the positive electrode active material 1. In addition, at the end of the conveying member 11, the heat-resistant materials 13b arranged opposite to each other are arranged to mesh with each other. This can further suppress the positive electrode active material 1 from slipping off.

[0059] The conveying member 11 has the positive electrode active material holding portion 12b, and thus can push back the positive electrode active material 1 inward in the width direction at the end portion, thereby preventing the positive electrode active material 1 from slipping off. In addition, since the strength of the conveying member 11 at the end portion is increased, pressure is more likely to be applied to the end portion than to the center in the width direction when the conveying member 11 comes into contact with the heating roller 31, and the movement of the positive electrode active material 1 outward in the width direction is prevented, and further the positive electrode active material 1 is prevented from slipping off.

[0060] 5 is a widthwise cross-sectional view of a transport member 11 including a positive active material holding portion 12c. The positive active material holding portion 12c is an end portion of the transport member 11, and is a guide member (conveyor) arranged between the opposing transport members 11. The positive active material holding portion 12c is arranged along the transport direction of the transport member 11. In FIG. 5, the positive active material holding portion 12c is each end portion of the transport member 11, and is arranged between the opposing transport members 11. The positive active material holding portion 12c (guide member) is, for example, a heat-resistant member such as a glass fiber sheet.

[0061] 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 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 may be set to 110% or more and 200% or less of the thickness of the positive electrode active material 1.

[0062] Since the conveying member 11 has the positive electrode active material holding portion 12c, the positive electrode active material 1 can be pushed back inward in the width direction at the end portion, and the positive electrode active material 1 can be prevented from slipping off. In addition, since the strength of the conveying member 11 at the end portion is increased, pressure is more likely to be applied to the end portion than to the center in the width direction when the conveying member 11 comes into contact with the heating roller 31, and the movement of the positive electrode active material 1 outward in the width direction is prevented, and further the positive electrode active material 1 is prevented from slipping off.

[0063] FIG. 6 is a widthwise cross-sectional view of a conveying 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 conveying member 11 arranged on the upper and lower surfaces of the positive electrode active material 1. In FIG. 6, the positive electrode active material holding portion 12d is formed by narrowing each end of the conveying member 11. When the conveying member 11 has the positive electrode active material holding portion 12d, a heating roller 31 having a protrusion 31d at the end corresponding to the positive electrode active material holding portion 12d is used. In FIG. 6, the heating roller 31 has a protrusion 31d at each end.

[0064] The total thickness of the protrusion 31d at one 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 total thickness of the protrusion 31d at one end may be set to 110% or more and 200% or less of the thickness of the positive electrode active material 1. By providing the protrusions 31d at both ends of the heating roller 31, a predetermined recess is formed in the heating roller 31. As shown in FIG. 6, the positive electrode active material 1 is heated inside the recess. Therefore, the width of the protrusion 31d and the recess is appropriately set according to the width of the positive electrode active material 1.

[0065] In this way, the combination of the positive electrode active material holding portion 12d and the recessed portion 31d can push back the positive electrode active material 1 inward in the width direction at the end portion, and can suppress the positive electrode active material 1 from slipping off. In addition, since pressure is easily applied to the end portion of the heating roller 31, the positive electrode active material 1 is suppressed from moving outward in the width direction, and furthermore, the positive electrode active material 1 is suppressed from slipping off. The positive electrode active material holding portion 12d may be formed by the protruding portion 31d, or may be formed by narrowing the end portion of the conveying member 11 in advance.

[0066] 6, the protrusions 31d are provided on the heating rollers 31 arranged on the upper and lower sides of the positive electrode active material 1, but the present invention is not limited thereto, and the protrusions 31d may be provided on either one of the heating rollers 31. In this case, the protrusions 31d press the positive electrode active material holder 12d against the other heating roller 31 that does not have the protrusions 31d. This provides the above-mentioned effect.

[0067] Although specific examples of the positive electrode active material holding portion have been shown above, the form of the positive electrode active material holding portion is not limited thereto, and any form capable of suppressing the positive electrode active material 1 from slipping off can be used. Furthermore, by having the positive electrode active material holding portion on the conveying member 11, it is possible to suppress the positive electrode active material 1 from slipping off. Therefore, according to the device 100, it is possible to improve the manufacturing productivity of the positive electrode active material 2.

[0068] <Forming means 20> The forming means 20 is a member that forms the positive electrode active material 1 into a sheet shape. As shown in FIG. 1, the forming means 20 is disposed upstream of the heating unit 30 in the conveying direction. In the manufacturing apparatus 100, the forming means 20 is an optional member. This is because the positive electrode active material 2 may be formed into a sheet shape in advance, as described above.

[0069] The molding means 20 may be a powder amount control member that controls the powder amount of the conveyed positive electrode active material 1 and molds it into a sheet shape. For example, it may be a powder amount control knife as shown in Fig. 1. Another example is a member that presses the positive electrode active material 1 to mold it into a sheet shape.

[0070] The thickness of the sheet-like positive electrode active material 1 formed by the forming means 20 is not particularly limited, and may be, for example, 0.1 mm or more, 0.5 mm or more, 1 mm or more, 2 mm or more, 50 mm or less, 30 mm or less, less than 30 mm, 20 mm or less, 10 mm or less, or 5 mm or less.

[0071] <Heating section 30> The heating unit 30 heats (fires) the positive electrode active substance 1. As shown in Fig. 1, the heating unit 30 is a rectangular housing, and has six heating rollers 31 (heating means) therein.

[0072] The heating unit 30 may heat the positive electrode active material 1 to 700°C or more, 800°C or more, 900°C or more, 1100°C or less, or 1000°C or less. A person skilled in the art can set the temperature at which the positive electrode active material 1 can be appropriately baked. The positive electrode active material 1 is heated by contacting the heating roller 31 as described later. Therefore, in practice, the heating roller 31 is heated to a predetermined temperature. The temperatures of the heating rollers 31 may be the same or different. For example, the heating roller 31 arranged on the upstream side in the conveying direction may be set to a low temperature for the purpose of oxidation, and the heating roller 31 arranged on the downstream side in the conveying direction may be set to a high temperature for the purpose of baking.

[0073] The heating section 30 may heat the positive electrode active material 1 under an oxidizing atmosphere. This is to promote the oxidation reaction of the positive electrode active material 1. The heating section 30 is equipped with an air blowing section (not shown) to create an oxidizing atmosphere inside. The heating section 30 can be maintained in an oxidizing atmosphere by supplying air or oxygen from the air blowing section to the inside of the heating section. Air or oxygen may be continuously supplied so as to keep the heating section 30 under negative pressure. A known blower or the like may be used as the air blowing section. Note that, when the positive electrode active material does not contain a material that undergoes an oxidation reaction, it is not necessary to oxidize the positive electrode active material 1 in the heating section 30, and therefore the heating section 30 does not need to be in an oxidizing atmosphere.

[0074] In this specification, the term "oxidizing atmosphere" refers to an atmosphere capable of oxidizing a target material. For example, it refers to an atmosphere in a space filled with a gas (e.g., air or oxygen) containing 1% or more of oxygen. The oxygen concentration in the space can be appropriately set according to the rate at which the oxidation of the target material progresses.

[0075] (heat roller 31) The heating roller 31 (heating means) is a member that heats the positive electrode active material 1 by thermal conduction. "Heating the positive electrode active material 1 by thermal conduction" means so-called contact heating. The heating roller 31 heats the positive electrode active material 1 via the transport member 11. Therefore, the heat of the heating roller 31 is transferred to the transport member 11, and then to the positive electrode active material 1, so that the positive electrode active material 1 is heated. The heating roller 31 may be brought into contact with the positive electrode active material 1 via another member in addition to the transport member 11 to heat the positive electrode active material 1.

[0076] The heating roller 31 heats the positive electrode active material 1 by contact heating, and is characterized by being able to efficiently heat the contact area and having high thermal uniformity at the contact area. Therefore, the calcination time of the positive electrode active material 1 can be reduced, and the variation in crystallinity can also be suppressed. In addition, since contact heating has high thermal uniformity, two heating steps, a calcination step and a calcination step, were previously required to manufacture a positive electrode active material, but the manufacturing apparatus 100 can calcinate the positive electrode active material in one step to obtain the positive electrode active material. Therefore, the manufacturing apparatus 100 can improve the productivity of manufacturing the positive electrode active material. In addition, the shortening of the heating time can also reduce the size of the equipment.

[0077] By employing the heating roller 31 as the heating means, the positive electrode active material 1 can be heated while being transported, so that the positive electrode active material 2 can be produced continuously.

[0078] As shown in Fig. 1, the heating unit 30 includes six heating rollers 31. The arrangement and number of the heating rollers 31 are not particularly limited, but as shown in Fig. 1, a heating roller for heating one side (e.g., the upper side) of the positive electrode active material 1 and a heating roller for heating the other side (e.g., the lower side) of the positive electrode active material 1 may be alternately arranged from the upstream to the downstream in the conveying direction. This allows both sides of the positive electrode active material 1 to be heated evenly, thereby reducing temperature unevenness of the positive electrode active material 1.

[0079] In addition, adjacent heating rollers 31 may be arranged to face each other so as to sandwich the positive electrode active material 1. This allows both sides of the positive electrode active material 1 to be heated simultaneously, improving the heating efficiency and reducing temperature unevenness. In addition, by arranging adjacent heating rollers 31 to face each other, the positive electrode active material 1 can be heated by applying pressure. That is, the positive electrode active material 1 can be heated and molded into a sheet shape. By adjusting the gap between the opposing heating rollers 31, the thickness of the sheet-shaped positive electrode active material 1 can be adjusted. For example, the gap between the opposing heating rollers 31 may be gradually narrowed from the upstream side to the downstream side in the conveying direction. This allows the heating rollers 31 to be arranged so as to reliably sandwich the positive electrode active material 1, thereby reducing temperature unevenness of the positive electrode active material 1. Note that since the heating rollers 31 are not intended to mold the positive electrode active material 1, the gap between the heating rollers 31 does not need to be strictly adjusted.

[0080] In Fig. 1, adjacent heating rollers are arranged to face each other. As can be seen from Fig. 1, a wrap angle is set for each heating roller 31 except for the most upstream and most downstream heating rollers 31. Fig. 7 shows a diagram for explaining the wrap angle. Fig. 3 shows an enlarged view of the heating roller 31 in Fig. 8.

[0081] The "holding angle" is the central angle of the heating roller 31, as shown by "x" in Fig. 7 and Fig. 8, which is obtained from the range from when the positive electrode active material 1 (transport path 11) contacts the heating roller 31 to when it is peeled off. As shown in Fig. 7, by setting the holding angle x to the heating roller 31, the contact area between the heating roller 31 and the positive electrode active material 1 can be increased, and the heating efficiency can be improved. In addition, since the positive electrode active material 1 can be handled and moved, it is possible to reduce uneven heating and promote gas exchange. It is also possible to suppress adhesion of the positive electrode active material 1 to the heating roller 31. Furthermore, the positive electrode active material 1 sandwiched between the heating rollers 31 arranged opposite to each other is heated from both sides and sintered, while the positive electrode active material 1 that is not sandwiched between the heating rollers 31 but in contact with one of the heating rollers 31 is heated at the contact surface while gas exchange can be performed from the open surface that is not in contact with the heating roller 31, so that the sintering of the positive electrode active material 1 can be promoted. Therefore, by arranging the heating rollers 31 as shown in Figures 1 and 8, heating of both sides of the positive electrode active material 1 (heat molding) and heating of one side of the positive electrode active material 1 can be performed alternately, whereby heating and efficient gas exchange are performed alternately, promoting sintering.

[0082] The wrap angle x of the heating roller 31 is not particularly limited, but may be 10° or more, 20° or more, 180° or less, or 90° or less, in the arrangement of FIG. 1. If the wrap angle of the heating roller is less than 10°, it is difficult to handle and move the positive electrode active material 1. On the other hand, there is no disadvantage due to 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 is likely to slip off the end of the conveying member 11 at a location near the vertical direction of the heating roller 31, but such slipping is suppressed by the conveying member 11 having a positive electrode active material holding portion. However, in the arrangement of FIG. 1, it is better to set the wrap angle of the heating roller 31 to 180° or less due to structural problems. The form in which the wrap angle of the heating roller 31 exceeds 180° will be described in the second embodiment described later.

[0083] 8, the heating rollers 31 are arranged such that a straight line connecting the centers of adjacent heating rollers 31 overlaps with one of the straight lines forming an embrace angle. This allows the positive electrode active material 1 to be constantly in contact with the heating roller 31, improving the heating efficiency and shortening the heating time.

[0084] 8, the wrap angles are set for the heating rollers 31 other than the most upstream and most downstream heating rollers 31, but the wrap angles may be set for the most upstream and most downstream heating rollers 31. For example, the wrap angles for the most upstream and most downstream heating rollers 31 can be set to desired values ​​by using a touch roll.

[0085] There is no particular limitation on the material of the heating roller 31. For example, the heating roller 31 may be made of a material having a heat resistance of 1000° C. or higher. Examples of such materials include inorganic materials such as ceramics and metal materials such as iron.

[0086] The rotation direction of the heating roller 31 may be forward (rotating in the same direction as the conveying direction) or reverse (rotating in the opposite direction to the conveying direction). The rotation speed of the heating roller 31 is not particularly limited. Those skilled in the art can appropriately select the optimal rotation direction and rotation speed that achieves both uniform heating and economic efficiency.

[0087] The surface of the heating roller 31 may have an uneven shape. By having the uneven surface of the heating roller 31, the positive electrode active material 1 in contact with the heating roller 31 can be handled and moved, reducing uneven heating and promoting gas exchange. In addition, adhesion of the positive electrode active material 1 to the heating roller can be suppressed. Furthermore, as shown in FIG. 6(a)(b), the heating roller 31 may have a predetermined protrusion 31d in order to suppress the positive electrode active material 1 from slipping off.

[0088] The width of the heating roller 31 is not particularly limited, but may be set to, for example, the same length as the width of the conveying member 11. The diameter of the heating roller 31 is appropriately set in consideration of the size of the heating unit 30 and the appropriate heating of the positive electrode active material 1.

[0089] <Collection Division 40> The recovery section 40 is a member that recovers the positive electrode active material 2 obtained by the heating section 30. When the positive electrode active material 2 is sandwiched between the transport members 11 and transported as shown in FIG. 1, the transport members may be separated in the recovery section 40 to recover the positive electrode active material 2 therein. In order to separate the transport members 11 in this manner, a predetermined roller 41 may be appropriately arranged. The recovered positive electrode active material 2 may be crushed. The method of crushing the positive electrode active material 2 is not particularly limited, and the positive electrode active material 2 may be crushed with a hammer or the like after it is collected. In addition, when the positive electrode active material 1 is in a sheet form, the obtained positive electrode active material 2 is also in a sheet form and can be easily crushed. For example, as shown in FIG. 1, the positive electrode active material 2 is crushed simply by collecting it.

[0090] When a porous heat-resistant member is used for the transport member 11, the positive electrode active material 2 may be buried in the internal pores. In such a case, the positive electrode active material 2 buried inside can be recovered by applying vibration to the transport member 11 while it is turned upside down, or by blowing air onto the surface that is not in contact with the positive electrode active material 2 (arrow in FIG. 1), thereby improving productivity. An example of a device that applies vibration is a vibration knocker. An example of a device that blows air is an air blower.

[0091] <Cathode active material 2> The positive electrode active material 2 obtained by the manufacturing apparatus 100 has a composition in which lithium is inserted into a metal oxide. For example, the molar ratio of each metal element in the positive electrode active material 2 may be Li:Ni:Co:Mn=s:x:y:z (0.8≦s≦1.2, x=1-yz, 0≦y<1, 0≦z<1), or Li:Ni:Co:Al=s:x:y:z (0.8≦s≦1.2, x=1-yz, 0≦y<1, 0≦z<1). In addition, when the composition of the positive electrode active material 2 is Li s Ni x Coy Mn z (O) 2+α (0.8≦s≦1.2, x=1-yz, 0≦y<1, 0≦z<1, -0.5≦α<0.5), and Li s Ni x Co y Al z (O) 2+α (0.8≦s≦1.2, x=1-yz, 0≦y<1, 0≦z<1, −0.5≦α<0.5).

[0092] In addition, since the positive electrode active material 1 is sintered by contact heating, the variation in crystallinity of the resulting positive electrode active material 2 is suppressed. The variation in crystallinity is determined by measuring the crystallite size by XRD, and the optimum range of the crystallite size (unit: nm) is set in conjunction with the battery evaluation results of the positive electrode active material 2. For example, the range of the crystallite size may be approximately ±200 nm, ±100 nm, or ±50 nm.

[0093] [Second embodiment] Next, a second embodiment will be described. Fig. 9 shows a schematic diagram of a manufacturing apparatus 200 (sometimes referred to as "manufacturing apparatus 200" in this specification) for manufacturing a positive electrode active material for a lithium ion secondary battery according to the second embodiment. The manufacturing apparatus 200 is obtained by changing the heating section 30 of the manufacturing apparatus 100 to a heating section 130. Specifically, the embrace angle x of the heating roller 31 is changed to more than 180°. The configuration other than the heating section 130 is the same as that of the manufacturing apparatus 100.

[0094] As shown in Fig. 9, the heating unit 130 has six heating rollers 131, similar to the heating unit 30. Furthermore, the embrace angle x of the heating rollers 131 is larger than that of the heating rollers 31 of the heating unit 30. Specifically, the embrace angle x of the heating rollers 131 is greater than 180° and is equal to or smaller than 360°. Fig. 10 shows a diagram for explaining the embrace angle x of the heating rollers 131. The explanation of the embrace angle x has been given above, so it will not be repeated here.

[0095] By making the embrace angle x of the heating roller 131 exceed 180°, the positive electrode active material 1 is transported in the height direction, and thus the rolling of the positive electrode active material 1 during transport is promoted, improving the thermal uniformity and promoting gas exchange. This suppresses uneven oxidation of the positive electrode active material 2, which is the product, and improves the quality. In addition, the contact time between the heating roller 31 and the positive electrode active material 1 can be extended, making it possible to miniaturize the equipment.

[0096] By making the embrace angle x of the heating roller 131 exceed 180°, a strong tension is applied to the conveying member 11 when the positive electrode active material 1 is conveyed in the height direction, compared with the case where the embrace angle x is 180° or less, and the positive electrode active material 1 in the conveying member 11 is subjected to a load in the vertical direction, and there is a concern that it may slip off from the end. However, since the conveying member 11 has a predetermined positive electrode active material holding portion, such slipping off is suppressed. The embrace angle x of the heating roller 131 may be 210° or more, 240° or more, 270° or more, 300° or more, less than 360°, 350° or less, or 330° or less.

[0097] Moreover, unlike the heating section 30, the heating section 130 is provided with a touch roll 132. The touch roll 132 is used to set the wrap angle of the adjacent heating roller 131. The touch roll 132 may be disposed at a position facing the adjacent heating roller 31. In FIG. 9, the touch rolls 132 are provided at positions adjacent to the heating rollers 131 on the upstream and downstream sides in the conveying direction. In the manufacturing apparatus 200, the touch roll 132 is an optional member. Furthermore, the number of touch rolls 132 may be at least one. Furthermore, the position of the touch roll 132 is not particularly limited, and it may be disposed at a position adjacent to the heating roller 131 that sets the wrap angle x.

[0098] The material of the touch roll 32 is not particularly limited. For example, it can be appropriately selected from the materials of the heating roller 131. The length of the touch roll 132 in the width direction is not particularly limited, but may be set to, for example, the same length as the length of the conveying member 11 in the width direction. The diameter of the touch roll 132 can be appropriately set based on the size of the heating section 130 and the embrace angle of the heating roller 131.

[0099] The embrace angle x can be set by the arrangement of the heating roller 131 and the touch roll 132. FIG. 11 shows an enlarged view of the heating roller 131 and the touch roll 132. In FIG. 11, the adjacent heating rollers 31 are arranged to face each other so as to have a predetermined embrace angle x. By arranging them in this manner, the embrace angle x of the heating rollers 131 can be set to a desired value, except for the most upstream and most downstream heating rollers 131. In addition, the touch rolls 132 are arranged at positions adjacent to the upstream and downstream heating rollers 131 in the conveying direction. This allows the embrace angle of the most upstream and most downstream heating rollers 131 to be set to a desired value. Furthermore, as shown in FIG. 11, the heating rollers 131 are arranged so that the straight line connecting the centers of the adjacent heating rollers 131 overlaps with one of the straight lines forming the embrace angle. This allows the positive electrode active material 1 to be constantly in contact with the heating roller 131, improving the heating efficiency and shortening the heating time.

[0100] [Third embodiment] Next, a third embodiment will be described. Fig. 12 shows a schematic diagram of a manufacturing apparatus 300 for manufacturing a positive electrode active material for a lithium ion secondary battery (sometimes referred to as "manufacturing apparatus 300" in this specification) according to the third embodiment. In the manufacturing apparatus 300, the heating section 30 of the manufacturing apparatus 100 is changed to a heating section 230. Specifically, the heating roller 31 is changed to a plate-shaped heating means 231. The configuration other than the heating section 230 is the same as that of the manufacturing apparatus 100.

[0101] The plate-shaped heating means 231 is a plate-shaped heating means, and as shown in FIG. 12, a pair of upper and lower plate-shaped heating means 231 are arranged in three rows in the conveying direction. The plate-shaped heating means 231 are raised and lowered to sandwich and heat the positive electrode active material 1 (conveying member 11). At this time, pressure molding may be performed. Note that, during heating, the conveying member 11 is temporarily stopped. In this way, contact heating can be realized even when the plate-shaped heating means 131 is used as the heating means.

[0102] The plate-shaped heating means 231 may be made of the same material as that of the heating roller 31. The size, area, etc. of the plate-shaped heating means 231 may be set appropriately.

[0103] [supplement] In the manufacturing apparatuses 100, 200, and 300, a plurality of heating means (heat rollers, plate-shaped elastic members) are used, but the manufacturing apparatus of the present disclosure is not limited thereto, and may have at least one heating means. This is because the number of heating means necessary for firing the positive electrode active material 1 may be installed. In addition, the shape of the heating means is not limited to roll-like and plate-like, and heating means of various shapes may be adopted. This is because any shape that can realize contact heating may be used. In addition, according to the first and second embodiments, the embrace angle x of the heating roller is not limited, and may be appropriately selected from the range of 0° or more and 360° or less.

[0104] 2. Manufacturing method of positive electrode active material for lithium-ion secondary batteries The method for producing a positive electrode active material for a lithium ion secondary battery according to the present disclosure will be described with reference to the following first to third embodiments.

[0105] [First embodiment] The method for producing a positive electrode active material for a lithium ion secondary battery according to the present disclosure will be described with reference to a first embodiment of the method for producing a positive electrode active material for a lithium ion secondary battery (sometimes referred to as "production method 1000" in this specification).

[0106] Fig. 13 shows a flow chart of a method for producing a positive electrode active material for a lithium ion secondary battery according to a first embodiment (sometimes referred to as "production method 1000" in this specification). As shown in Fig. 13, the production method 1000 includes a positive electrode active material preparation step S1, a forming step S2, a heating step S3, and a recovery step S4. The forming step S2, the heating step S3, and the recovery step S4 can be performed by a production apparatus according to the present disclosure.

[0107] <Positive electrode active material preparation process S1> The positive electrode active material preparation step S1 is a step of mixing a metal compound and a lithium compound to obtain a positive electrode active material. Here, the metal compound, the lithium compound, and the positive electrode active material have been described above, so they will not be described here. Also, the mixing method has been described above, so they will not be described here.

[0108] <Forming process S2> The forming step S2 is an optional step and is provided before the processing step S3. The forming step S2 is a step of forming the positive electrode active material into a sheet shape. The method of forming the positive electrode active material into a sheet shape is not particularly limited. For example, the above-mentioned forming method can be adopted.

[0109] <Heating process S3> The heating step S3 is a step of heating (firing) the positive electrode active material. Specifically, the heating step S3 is a step of heating the positive electrode active material by thermal conduction. The method of heating the positive electrode active material has been described above, so the description will be omitted here.

[0110] <Recovery process S4> The recovery step S4 is a step of recovering the positive electrode active material obtained by the heating step S3. The method of recovering the positive electrode active material is not particularly limited. For example, the recovery method described above can be adopted.

[0111] [Second embodiment] Next, the second embodiment will be described. FIG. 14 shows a manufacturing method 2000 of a positive electrode active material for a lithium ion secondary battery (sometimes referred to as "manufacturing method 2000" in this specification) according to the second embodiment. The manufacturing method 2000 is obtained by adding an oxidizing roasting step S5 to the manufacturing method 1000. The oxidizing roasting step S5 is provided before the positive electrode active material preparation step S1, and is a step of heating a metal hydroxide under an oxidizing atmosphere. The oxidizing roasting method of the metal hydroxide has been described above, so it will not be described here. By providing the oxidizing roasting step S5, a metal oxide can be obtained. Since the oxidation of the metal hydroxide is an endothermic reaction, there is a risk of temperature unevenness occurring when a positive electrode active material containing a metal hydroxide is used in the heating step S3. Therefore, the manufacturing method 2000 includes the oxidizing roasting step S5 to oxidize the metal hydroxide in advance. However, since contact heating is adopted in the heating step S3, temperature unevenness is reduced even when a positive electrode active material containing a metal hydroxide is used.

[0112] [Third embodiment] Next, a third embodiment will be described. FIG. 15 shows a manufacturing method 3000 of a positive electrode active material for a lithium ion secondary battery according to the third embodiment (sometimes referred to as "manufacturing method 3000" in this specification). The manufacturing method 3000 includes a calcination step S6 before the molding step S2. The calcination step S6 is a step of heating the positive electrode active material in an oxidizing atmosphere. The calcination step S6 can oxidize metal hydroxides to metal oxides and lithium compounds such as lithium hydroxides to lithium oxides. Since such an oxidation reaction is an endothermic reaction, the oxidation of the positive electrode active material is completed by the calcination step S6, thereby reducing the temperature unevenness of the positive electrode active material in the heating step S3 and enabling firing in a short time. However, since the heating step S3 employs contact heating, the positive electrode active material including metal hydroxides can be appropriately fired to obtain a positive electrode active material without providing the calcination step 2.

[0113] The heating temperature in the calcination step 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 performed using a calcination device such as a rotary kiln.

[0114] [supplement] In the manufacturing method of the present disclosure, the oxidizing roasting step and the calcination step may be combined.

[0115] 3.Effects The manufacturing apparatus and manufacturing method of the positive electrode active material for lithium ion secondary batteries according to the present disclosure have been described above using each embodiment. The present disclosure employs contact heating to heat the positive electrode active material material by thermal conduction. Contact heating is characterized by being able to efficiently heat the contact area and having small temperature unevenness (high thermal uniformity) at the contact area. Therefore, the present disclosure employing contact heating can reduce the baking time of the positive electrode active material and can also suppress variations in crystallinity. Moreover, unlike the conventional technology, the present disclosure can bake the positive electrode active material material in one heating section (heating step) to obtain the positive electrode active material. Therefore, according to the present disclosure, the productivity of the manufacturing of the positive electrode active material can be improved. Furthermore, the shortening of the heating time can also reduce the size of the equipment.

[0116] In addition, the present disclosure has a predetermined positive electrode active material holding portion at the end of the conveying member, which can prevent the positive electrode active material 1 from slipping off. Therefore, according to the present disclosure, the manufacturing productivity of the positive electrode active material 2 can be further improved. EXAMPLES

[0117] The present disclosure will now be further described with reference to examples.

[0118] A manufacturing apparatus was prepared according to FIG. 9. A mixture of nickel cobalt manganese oxide and lithium carbonate was prepared as a positive electrode active material. The positive electrode active material was placed on a conveying member and heated by a heating unit to produce a positive electrode active material. At this time, the temperature of the heating roller was set to 950°C to 1000°C. In addition, the wrap angle of all the heating rollers was set to more than 180°.

[0119] In the examples, a conveying member was used that had a positive electrode active material holding portion formed by folding an end portion multiple times, following the example of Fig. 3. In the comparative examples, a conveying member that did not have a positive electrode active material holding portion was used.

[0120] Based on the above, the production of the positive electrode active material was carried out five times under the conditions of each of the examples and the 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 assuming that the weight of the positive electrode active material when all the positive electrode active material material was recovered as the positive electrode active material was 100%. As a result, the recovery rate of the positive electrode active material in the comparative example was about 58 to 67%, while the recovery rate of the positive electrode active material in the examples was 98% to 100%. The difference in the results is considered to be due to the positive electrode active material material being prevented from slipping off by the positive electrode active material material retaining portion. [Industrial Applicability]

[0121] The positive electrode active material produced according to the present disclosure can be used in the positive electrodes of any of non-aqueous lithium ion secondary batteries, aqueous lithium ion secondary batteries, and all-solid-state lithium ion secondary batteries. [Explanation of symbols]

[0122] 1 Cathode active material 2 Cathode active material 10. Means of transportation 11 Transport member 12a, 12b, 12c, 12d Positive electrode active material holding part 20 Forming means 30, 130, 230 heating section 31, 131 Heating roller (heating means) 31d protrusion 40 Collection Department 41 Roller 132 Touch Roll 231 Plate-shaped heating means (heating means) 100, 200, 300 Manufacturing equipment for positive electrode active materials for lithium ion secondary batteries

Claims

1. A positive electrode active material comprising a metal compound containing at least one metal element selected from the group consisting of nickel, cobalt, and manganese, and a lithium compound; A heating unit that heats the positive electrode active material, the heating unit has at least one heating means for heating the positive electrode active material by thermal conduction, the transport means has a transport member that transports the positive electrode active material, the heating means is a heating roller, and heats the positive electrode active material through the conveying member; The conveying member has a positive electrode active material retaining portion at an end in a width direction. Manufacturing equipment for positive electrode active materials for lithium-ion secondary batteries.

2. A conveying means for conveying a positive electrode active material including a metal compound including at least one metal element selected from the group consisting of nickel, cobalt, and manganese, and a lithium compound; A heating unit that heats the positive electrode active material, the heating unit has at least one heating means for heating the positive electrode active material by thermal conduction, the transport means has a transport member that transports the positive electrode active material, The heating means heats the positive electrode active material through the conveying member, the conveying member has a positive electrode active material holding portion at an end in a width direction, the heating means is a plurality of heating rollers, the heating roller for heating one surface of the positive electrode active material and the heating roller for heating the other surface of the positive electrode active material are alternately arranged from the upstream side to the downstream side in a conveying direction, The adjacent heating rollers are arranged to face each other so as to sandwich the positive electrode active material therebetween. Manufacturing equipment for positive electrode active materials for lithium-ion secondary batteries.

3. The manufacturing apparatus according to claim 1 or 2, wherein the wrap angle of the heating roller is greater than 180° and is equal to or less than 360°.

4. The manufacturing apparatus according to any one of claims 1 to 3, wherein the heating section heats the positive electrode active material to 700°C or higher and 1000°C or lower.

5. The manufacturing apparatus according to any one of claims 1 to 4, wherein the heating section heats the positive electrode active material in an oxidizing atmosphere.

6. 6. The manufacturing apparatus according to claim 1, wherein the transport member is made of a porous heat-resistant member.

7. The manufacturing apparatus according to any one of claims 1 to 6, further comprising a forming means for forming the positive electrode active material into a sheet upstream of the heating section in a conveying direction.

8. The manufacturing apparatus according to any one of claims 1 to 7, further comprising a recovery section that recovers the positive electrode active material obtained by the heating section.

9. A positive electrode active material preparation process comprising mixing a metal compound containing at least one metal element selected from the group consisting of nickel, cobalt, and manganese with a lithium compound to obtain a positive electrode active material; A heating step of heating the positive electrode active material, The heating step heats the positive electrode active material by thermal conduction, In the heating step, the positive electrode active material is transported by a transport member, and the positive electrode active material is heated via the transport member, the conveying member has a positive electrode active material holding portion at an end in a width direction, In the heating step, the positive electrode active material is heated while being conveyed. A method for producing a positive electrode active material for a lithium ion secondary battery.

10. The method according to claim 9 , wherein the heating step alternates between heating both sides of the positive electrode active material and heating one side of the positive electrode active material.

11. The method according to claim 9 or 10, wherein in the heating step, the positive electrode active substance material is heated using a heating roller having a wrap angle of more than 180° and not more than 360°.

12. The method according to any one of claims 9 to 11, wherein the heating step heats the positive electrode active material to 700°C or higher and 1000°C or lower.

13. The method according to any one of claims 9 to 12, wherein the heating step heats the positive electrode active material in an oxidizing atmosphere.

14. The manufacturing method according to any one of claims 9 to 13, wherein the transport member is made of a porous heat-resistant member.

15. The method according to any one of claims 9 to 14, further comprising a forming step of forming the positive electrode active material into a sheet prior to the heating step.

16. The method according to any one of claims 9 to 15, further comprising a recovery step of recovering the positive electrode active material obtained by the heating step.

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