Manufacturing Apparatus and Manufacturing Method for Positive Electrode Active Material for Lithium Ion Secondary Battery

Abstract

Provided is a manufacturing apparatus for a positive electrode active material for a lithium ion secondary battery, which can improve productivity. A manufacturing apparatus for a positive electrode active material for a lithium ion secondary battery includes a transport unit and a heating unit. The transport unit transports a positive electrode active material material containing a lithium compound and the following metal compound. The metal compound contains at least one metal element selected from nickel, cobalt, and manganese. The heating unit heats the positive electrode active material material. The heating unit has at least one heating unit, and the heating unit heats the positive electrode active material material by heat conduction.

Description

Technical Field

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

[0002] Lithium ion secondary batteries are widely used as power sources for laptop computers, portable terminals, etc., and power sources for vehicle drive. Therefore, it is required to improve the productivity of lithium ion secondary batteries, and it is also required to improve the productivity of the positive electrode active material used in lithium ion secondary batteries.

[0003] A general 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 (such as lithium hydroxide, lithium carbonate, etc.) are mixed to obtain a positive electrode active material precursor. Next, the positive electrode active material precursor is pre-fired to oxidize the positive electrode active material precursor. Specifically, the metal hydroxide is oxidized to a metal oxide, and the lithium compound is oxidized to lithium oxide. Next, the pre-fired positive electrode active material precursor is filled into a prescribed crucible and fired. By firing, the metal oxide and lithium oxide in the positive electrode active material precursor react to obtain a lithium metal oxide as the positive electrode active material. Moreover, the obtained positive electrode active material is recovered and used for a lithium ion secondary battery. For example, such a method for manufacturing a positive electrode active material is disclosed in Patent Documents 1 to 3.

[0004] In the step of pre-firing the positive electrode active material precursor, a firing apparatus such as a rotary kiln is used. A rotary kiln is a device capable of heating the positive electrode active material precursor while stirring in an oxidizing atmosphere, and can promote the oxidation of the positive electrode active material precursor. Regarding the reason for pre-firing the positive electrode active material precursor, since the oxidation reaction of the metal hydroxide and the lithium compound is an endothermic reaction, it is to prevent temperature unevenness of the positive electrode active material precursor due to the endothermic reaction in the firing step.

[0005] In the step of firing the positive electrode active material precursor, a firing apparatus such as a roller hearth kiln is used. A roller hearth kiln can heat the positive electrode active material precursor at a temperature higher than that in the pre-firing step, and can manufacture a positive electrode active material by reacting the metal oxide and lithium oxide in the positive electrode active material precursor. In addition, when filling the positive electrode active material precursor into the crucible, pressure may be applied for densification. By densifying the positive electrode active material precursor, the contact area between the metal oxide and lithium oxide in the positive electrode active material precursor increases, and firing can be promoted.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Laid-Open No. 2020-113429

[0009] Patent Document 2: Japanese Patent Laid-Open No. 2019-175694

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

[0011] Since a rotary kiln is a device for oxidizing metal hydroxides and / or lithium compounds, it is necessary to actively supply air or oxygen into the rotary kiln to form an oxidizing atmosphere. However, since it is necessary to actively supply air or oxygen into the rotary kiln, the production cost increases.

[0012] A roller hearth kiln is a device for firing a pre-fired positive electrode active material. In order to heat uniformly, it is necessary to fill the positive electrode active material into a sagger. However, depending on the flow pattern of the hot air in the device, the positive electrode active material is likely to have non-uniform temperature. When the positive electrode active material is heated for a short time in a state where there is non-uniform temperature, the crystallinity of the manufactured positive electrode active material deviates. Therefore, when manufacturing a positive electrode active material using a roller hearth kiln, in order to suppress non-uniform temperature, it is necessary to heat the positive electrode active material for a long time, but this increases the production cost. In addition, since it is necessary to heat for a long time, the equipment tends to be large-sized.

[0013] Therefore, an object of the present application is to provide a manufacturing apparatus and a manufacturing method for a positive electrode active material for a lithium ion secondary battery that can improve productivity.

[0014] As a means for solving the above problems, the present disclosure provides a manufacturing apparatus for a positive electrode active material for a lithium ion secondary battery, which includes: a transport unit that transports a positive electrode active material including a lithium compound and the following metal compound, the metal compound including at least one metal element selected from nickel, cobalt, and manganese; and a heating unit that heats the positive electrode active material, the heating unit having at least one heating unit that heats the positive electrode active material by heat conduction.

[0015] In the above manufacturing apparatus, the heating unit may be a heating roller. Alternatively, it may be that: the heating unit is a plurality of heating rollers, and 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 the transport direction, and adjacent heating rollers are arranged facing each other with the positive electrode active material sandwiched therebetween. Further, the wrap angle of the heating roller may be 10° or more and 180° or less.

[0016] In the above manufacturing apparatus, the heating unit may heat the positive electrode active material to a temperature of 700° C. to 1000° C. In addition, the heating unit may heat the positive electrode active material in an oxidizing atmosphere.

[0017] In the above-mentioned manufacturing apparatus, the transport unit may include a transport member formed of a porous heat-resistant member, and the heating unit may heat the positive electrode active material via (through) the porous heat-resistant member.

[0018] The manufacturing apparatus may include a forming unit for forming the positive electrode active material into a sheet shape on the upstream side of the heating unit in the conveying direction. Also, a recovery unit for recovering the positive electrode active material obtained by the heating unit may be provided.

[0019] As a means for solving the above-mentioned problems, the present disclosure provides a method for manufacturing a positive electrode active material for a lithium ion secondary battery, which comprises: a positive electrode active material preparation step, mixing a lithium compound and the following 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; and a heating step, heating the positive electrode active material, in which the positive electrode active material is heated by heat conduction.

[0020] In the above manufacturing method, in the heating step, the positive electrode active material can be heated while being transported. In addition, in the heating step, the heating of both sides of the positive electrode active material and the heating of one side of the positive electrode active material can be performed alternately. Furthermore, in the heating step, a heating roller having a wrap angle of 10° or more and 180° or less can be used to heat the positive electrode active material.

[0021] In the above manufacturing method, in the heating step, the positive electrode active material may be heated to 700° C. or higher and 1000° C. or lower. In the heating step, the positive electrode active material may be heated in an oxidizing atmosphere. Furthermore, in the heating step, the positive electrode active material may be heated through a porous heat-resistant member.

[0022] In the above-mentioned production method, a forming unit for forming the positive electrode active material into a sheet shape may be provided before the heating step. In addition, a recovery step for recovering the positive electrode active material obtained in the heating step may be provided.

[0023] The roller kiln used in the past heats the positive electrode active material by heating the air in the kiln. In other words, the positive electrode active material is heated by convection heating. In convection heating, as mentioned above, the positive electrode active material is prone to temperature non-uniformity depending on the flow of hot air in the kiln, so there is a problem that a long firing time is required.

[0024] On the other hand, the present disclosure employs contact heating that heats the positive electrode active material through heat conduction. Contact heating is characterized by being able to efficiently heat the contact part, and the temperature non-uniformity of the contact part is small (high heat uniformity). Therefore, in the present disclosure that employs contact heating, the firing time of the positive electrode active material can be reduced, and the deviation of crystallinity can also be suppressed. In addition, different from the prior art, the present disclosure can use one heating unit (heating process) to fire the positive electrode active material to obtain the positive electrode active material. Therefore, according to the present disclosure, the productivity of manufacturing the positive electrode active material can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of a manufacturing apparatus 100 for a positive electrode active material for a lithium ion secondary battery.

[0026] Figure 2 is a diagram for explaining the wrap angle x.

[0027] Figure 3 is an enlarged view of the heating roller 31.

[0028] Figure 4 is a schematic diagram of a manufacturing apparatus 200 for a positive electrode active material for a lithium ion secondary battery.

[0029] Figure 5 is a flowchart of a manufacturing method 1000 for a positive electrode active material for a lithium ion secondary battery.

[0030] Figure 6 is a flowchart of a manufacturing method 2000 for a positive electrode active material for a lithium ion secondary battery.

[0031] Figure 7 is a flowchart of a manufacturing method 3000 for a positive electrode active material for a lithium ion secondary battery.

[0032] DESCRIPTION OF REFERENCE NUMERALS

[0033] 1: Positive electrode active material

[0034] 2: Positive electrode active material

[0035] 10: Conveying unit

[0036] 11: Conveying member

[0037] 20: Shaping unit

[0038] 30: Heating unit

[0039] 31: Heating roller (heating unit)

[0040] 40: Recovery unit

[0041] 131: Plate-shaped heating unit (heating unit)

[0042] 100, 200: Manufacturing apparatus for positive electrode active material for lithium ion secondary battery Detailed implementation mode

[0043] [Manufacturing apparatus for positive electrode active material for lithium ion secondary battery]

[0044] Regarding the manufacturing apparatus for positive electrode active material for lithium ion secondary battery of the present disclosure, an explanation will be given while referring to the manufacturing apparatus 100 for positive electrode active material for lithium ion secondary battery as an embodiment (in this specification, sometimes referred to as "manufacturing apparatus 100"). Figure 1 A schematic diagram of the manufacturing apparatus 100 is shown. Here, Figure 1 the left-right direction is taken as the conveying direction, the up-down direction is taken as the height direction, and the front-back direction is taken as the width direction.

[0045] As Figure 1 described, the manufacturing apparatus 100 includes a conveying unit 10, a forming unit 20, a heating unit 30, and a recovery unit 40. In addition, Figure 1 the positive electrode active material material 1 as a raw material and the positive electrode active material 2 as a product are described.

[0046] <Positive electrode active material material 1>

[0047] The positive electrode active material material 1 is a material containing a lithium compound and a metal compound. In addition, it may contain the deteriorated and shape-crushed positive electrode active material 2 such as a recycled material. Even if the deteriorated positive electrode active material 2 is included, it can be fired with high heat uniformity in the heating unit 30.

[0048] The positive electrode active material material 1 can be obtained by mixing these materials. The mixing method is not particularly limited, and a known method can be adopted. For example, a mortar can be used for mixing, or a blender can be used for mixing.

[0049] (Metal compound)

[0050] The metal compound is a compound containing at least one metal element selected from nickel, cobalt, and manganese. In addition, the metal compound may contain nickel, may contain nickel and cobalt, may contain nickel, cobalt, and manganese. Furthermore, other metal elements may be included. For example, the metal compound may further contain aluminum. In addition, the metal compound may contain aluminum instead of manganese.

[0051] For example, in the metal compound, the molar ratio of each metal 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).

[0052] The metal compound can be, for example, metal hydroxide, metal oxide, metal carbonate, and metal perhydroxide. These metal compounds can be used alone or in combination. Preferably, the metal compound is metal hydroxide or metal oxide.

[0053] As the metal hydroxide, a known metal hydroxide containing at least one metal 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 the metal oxide, a known metal oxide containing at least one metal element selected from nickel, cobalt, and manganese can be used. Examples include Ni x Co y Mn z (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).

[0054] The metal compound can be prepared by a known method. Hereinafter, an example of the preparation method of metal hydroxide and metal oxide is shown respectively. However, the preparation method of the metal compound is not limited thereto.

[0055] For example, as a method for preparing metal hydroxide, the crystallization method can be cited. Hereinafter, an example of the method for preparing metal hydroxide by the crystallization method is described.

[0056] First, dissolve the Ni source, Co source, and Mn source (or Al source) in an aqueous solvent (such as deionized water) to prepare a metal source solution. As the metal source, various metal salts (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 of adding these metal sources to the aqueous solvent is not particularly limited. Additionally, aqueous solutions of each metal source can be prepared separately and then mixed. The ratio of the metal sources is appropriately adjusted to obtain the desired metal hydroxide.

[0057] Next, while stirring in an inert gas atmosphere, dropwise add the metal source solution and NH 3 aqueous solution to the alkaline aqueous solution. An aqueous sodium hydroxide solution or the like can be used as the alkaline aqueous solution. The pH of the alkaline aqueous solution is set to, for example, 11 to 13. While maintaining a range of, for example, 5 g / L to 15 g / L, dropwise add the NH 3 aqueous solution. By dropwise adding the metal source solution and NH 3 aqueous solution to the alkaline aqueous solution, the pH of the reaction solution gradually decreases. Therefore, the alkaline aqueous solution can be appropriately dropwise added to maintain the pH within a specified range.

[0058] Then, after a certain period, perform suction filtration to recover the precipitate. By washing and drying the obtained precipitate, a metal hydroxide is obtained. The precipitate can be washed multiple times. The drying of the precipitate can be air drying or heat drying. Heat drying can be carried out at, for example, 120 to 180 °C.

[0059] The metal oxide can be produced by oxidatively roasting, for example, the metal hydroxide. Oxidative roasting means heating the 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, and 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, and is, for example, 0.5 hours to 3 hours. Such heating can be carried out using a firing device such as a rotary kiln.

[0060] The average particle size of the metal compound is not particularly limited and is, for example, in the range of 1 μm to 1 mm. In this specification, the so-called "average particle size" is the particle size at the cumulative value of 50% in the volume-based particle size distribution obtained by the laser diffraction / scattering method, that is, the median particle size.

[0061] The content ratio of the metal compound in the positive electrode active material is appropriately set to obtain the desired positive electrode active material.

[0062] (lithium compound)

[0063] The lithium compound is not particularly limited as long as it is a compound containing lithium, and known lithium compounds can be used. Examples include lithium oxide, lithium hydroxide, lithium nitrate, lithium carbonate, etc. Lithium hydroxide, lithium nitrate, lithium carbonate, etc. are converted into lithium oxide by oxidation.

[0064] The type of lithium compound is appropriately selected according to 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 a metal hydroxide or metal oxide containing nickel, cobalt, and manganese as the metal compound, a firing temperature of about 800 °C is required, so lithium carbonate is preferably selected. In addition, when using a metal hydroxide or metal oxide containing nickel, cobalt, and aluminum as the metal compound, a firing temperature of about 500 °C is required, so lithium hydroxide is preferably selected.

[0065] The content ratio of the lithium compound in the positive electrode active material material is appropriately set so as to obtain a desired positive electrode active material.

[0066] (Shape of the positive electrode active material material 1)

[0067] The shape of the positive electrode active material material 1 is not particularly limited and can be sheet-like. By making the positive electrode active material material 1 sheet-like, it becomes easy to heat it evenly to the inside. As a result, the non-uniform heating is reduced, and the deviation in the crystallinity of the manufactured positive electrode active material 2 is also suppressed. In addition, by making the shape of the positive electrode active material material 1 sheet-like, it can be easily disintegrated in the recovery unit 40.

[0068] The thickness of the sheet-like positive electrode active material 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, 50 mm or less, 30 mm or less, less than 30 mm, 20 mm or less, 10 mm or less, 5 mm or less. If the thickness of the sheet-like positive electrode active material material 1 is too thick, it is difficult to heat it evenly, and if it is too thin, the productivity decreases.

[0069] The positive electrode active material material 1 can be formed into a sheet shape by the forming unit 20 and / or the heating unit 31, but it can also be formed into a sheet shape in advance by press forming or the like. However, the positive electrode active material material 1 can also be formed into a sheet shape in advance, and then the positive electrode active material material 1 can be formed into a specified thickness by the forming unit 20 and / or the heating unit 31.

[0070] <Transport unit 10>

[0071] The transport unit 10 is a component for transporting the positive electrode active material material 1. As Figure 1As shown, the conveying unit 10 includes a conveying member 11 for conveying the positive electrode active material 1. In addition, a driving unit (not shown) for driving the conveying member 11 is provided.

[0072] (Conveying member 11)

[0073] The conveying member 11 is a member (conveyor) for conveying the positive electrode active material 1. The conveying member 11 is a sheet-like member and is driven from the upstream side to the downstream side in the conveying direction by the driving unit. Since the conveying member 11 conveys the positive electrode active material 1 in a state where it is placed, it needs to be arranged below the positive electrode active material 1. In addition, it can also be arranged above the positive electrode active material 1 as described in Figure 1 . That is, the positive electrode active material 1 can be conveyed in a state of being clamped by the conveying member 11.

[0074] As will be described later, the manufacturing apparatus 100 is an apparatus for heating the positive electrode active material 1 by contact heating. Therefore, the heating unit 31 can be directly contacted to heat the positive electrode active material 1, but in this case, the positive electrode active material 1 adheres to the heating unit 31, resulting in a decrease in productivity. Therefore, in the manufacturing apparatus 100, by making the heating unit 31 contact the positive electrode active material 1 with the conveying member 11 interposed therebetween, the adhesion of the positive electrode active material 1 to the heating unit 31 is suppressed. For this reason, when heating the upper and lower surfaces of the positive electrode active material 1, the positive electrode active material 1 can be sandwiched by the conveying member 11 for conveyance.

[0075] Since the conveying member 11 is in contact with the heating unit 31, it needs to be made of a member (heat-resistant member) that is resistant to the heating temperature of the heating unit 30. For example, the heat-resistant member needs to have a heat resistance of 900 °C or higher. Examples of such heat-resistant members include quartz glass cloth and silica fiber cloth.

[0076] Here, in the case where the positive electrode active material 1 contains a material that becomes an oxide by oxidation of a metal hydroxide, a lithium hydroxide, etc., in order to carry out the firing of the positive electrode active material 1, it is necessary to incorporate oxygen from the outside. In addition, gases such as water (water vapor) and carbon dioxide are generated by the firing of the positive electrode active material 1. 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 be constituted by a porous heat-resistant member capable of efficient gas exchange with the outside. The pore diameter of the porous heat-resistant member is not particularly limited as long as it is a size that enables efficient gas exchange and the positive electrode active material 1 does not leak to the outside. For example, the pore diameter of the pores of the porous heat-resistant member can be 20 μm or less, can be 10 μm or less, can be 5 μm or less, can be 3 μm or more, can be 1 μm or more, can be 0.5 μm or more. If the pore diameter of the pores of the porous heat-resistant member is too large, the positive electrode active material 1 is likely to leak to the outside, and if it is too small, the gas exchange efficiency with the outside is reduced. As such a porous heat-resistant member, a fibrous heat-resistant member can be cited. For example, quartz glass cloth and silica fiber cloth can be cited.

[0077] Here, the pore diameter of the porous heat-resistant member is the length of the diagonal of the mesh hole calculated from the fiber diameter and the product density (unit: number of roots / mm).

[0078] <Forming unit 20>

[0079] The forming unit 20 is a member that forms the positive electrode active material 1 into a sheet shape. As Figure 1 described, the forming unit 20 is arranged on the upstream side in the transport direction with respect to the heating unit 30. Furthermore, in the manufacturing apparatus 100, the forming unit 20 is an optional member. This is because, as described above, the positive electrode active material 1 can also be formed into a sheet shape in advance.

[0080] As the forming unit 20, a powder amount control member that controls the powder amount of the transported positive electrode active material 1 to be formed into a sheet shape can be cited. For example, it is the Figure 1 powder amount control knife described in. In addition, a member that presses the positive electrode active material 1 to form it into a sheet shape can be cited.

[0081] The thickness of the sheet-shaped 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, can be 0.5 mm or more, can be 1 mm or more, can be 2 mm or more, can be 50 mm or less, can be 30 mm or less, can be less than 30 mm, can be 20 mm or less, can be 10 mm or less, can be 5 mm or less.

[0082] <Heating unit 30>

[0083] The heating unit 30 is a device that heats (sinter) the positive electrode active material 1. As Figure 1 described, the heating unit 30 is a rectangular housing and includes six heating rollers 31 (heating units) inside.

[0084] The heating unit 30 can heat the positive electrode active material 1 to 700 °C or higher, can heat it to 800 °C or higher, can heat it to 900 °C or higher, can heat it to 1100 °C or lower, and can heat it to 1000 °C or lower. Those 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 contacting the heating roller 31 as described later. Therefore, the heating roller 31 is actually heated to a specified temperature. Furthermore, the temperatures of the heating rollers 31 can be the same or different. For example, the heating roller 31 arranged on the upstream side in the transport direction can be set to a low temperature for oxidation purposes, and the heating roller 31 arranged on the downstream side in the transport direction can be set to a high temperature for sintering purposes.

[0085] The heating unit 30 can 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 make the inside an oxidizing atmosphere, the heating unit 30 includes a blowing unit (not shown). By supplying air or oxygen from the blowing unit to the inside of the heating unit, the heating unit 30 can be maintained in an oxidizing atmosphere. In addition, air or oxygen can be continuously supplied in such a way that the heating unit 30 is maintained at a negative pressure. As the blowing unit, a known blower or the like can be used. Furthermore, when the positive electrode active material does not contain a material accompanied by an oxidation reaction, it is not necessary to oxidize the positive electrode active material 1 in the heating unit 30, so the heating unit 30 can be made not to be in an oxidizing atmosphere.

[0086] Here, in this specification, the so-called "oxidizing atmosphere" is an atmosphere that can oxidize the target material. For example, it is an atmosphere in a space filled by supplying a gas containing 1% or more of oxygen (such as air or oxygen). The oxygen concentration in the space can be appropriately set according to the progress rate of the oxidation of the target material.

[0087] (Heating roller 31)

[0088] The heating roller 31 (heating unit) is a component that heats the positive electrode active material 1 by heat conduction. The so-called "heating the positive electrode active material 1 by heat conduction" is so-called contact heating, which means heating the positive electrode active material 1 by directly or indirectly contacting the heating unit. The so-called "indirectly" means heating the positive electrode active material 1 by contacting the heating unit and the positive electrode active material 1 through other components. In Figure 1In this case, the heating roller 31 contacts the positive electrode active material 1 through the conveying member 11 to heat it. Alternatively, the heating unit may contact the positive electrode active material 1 through a member other than the conveying member 11, or through the conveying member 11 and other members. In this specification, unless otherwise specified, "direct or indirect contact" is simply expressed as "contact".

[0089] The heating roller 31 heats the positive electrode active material 1 by contact heating. It is characterized by being able to heat the contact part with high efficiency and having high heat uniformity of the contact part. Therefore, the firing time of the positive electrode active material 1 can be reduced, and the deviation of crystallinity can also be suppressed. In addition, due to the high heat uniformity of contact heating, although two heating processes, a pre-firing process and a firing process, were required to manufacture the positive electrode active material in the past, in the manufacturing apparatus 100, the positive electrode active material can be obtained by firing the positive electrode active material in one process. Therefore, according to the manufacturing apparatus 100, the productivity of manufacturing the positive electrode active material can be improved. In addition, by shortening the heating time, the equipment can also be miniaturized.

[0090] By using the heating roller 31 as the heating unit, the positive electrode active material 1 can be heated while being conveyed, so that continuous production of the positive electrode active material 2 can be achieved.

[0091] As Figure 1 described, the heating unit 30 includes six heating rollers 31. The arrangement method and number of the heating rollers 31 are not particularly limited, but as Figure 1 described, the heating rollers for heating one surface (e.g., the upper surface) of the positive electrode active material 1 and the heating rollers for heating the other surface (e.g., the lower surface) of the positive electrode active material 1 can be alternately arranged from the upstream to the downstream in the conveying direction. Thereby, the two surfaces of the positive electrode active material 1 can be heated evenly, so that the temperature non-uniformity of the positive electrode active material 1 is reduced.

[0092] In addition, adjacent heating rollers 31 can be arranged facing each other in such a way as to sandwich the positive electrode active material 1 therebetween. As a result, both sides of the positive electrode active material 1 can be heated simultaneously, so that the heating efficiency can be improved and the temperature non-uniformity can be reduced. In addition, by arranging adjacent heating rollers 31 facing each other, pressure can be applied and the positive electrode active material 1 can be heated. That is, the positive electrode active material 1 can be heated and formed into a sheet. By adjusting the gap between the facing heating rollers 31, the thickness of the sheet-like positive electrode active material 1 can be adjusted. For example, the gap between the facing heating rollers 31 can be gradually narrowed from the upstream side to the downstream side in the conveying direction. As a result, the heating rollers 31 can be arranged in such a way as to reliably sandwich the positive electrode active material 1, so that the temperature non-uniformity of the positive electrode active material 1 is reduced. Furthermore, since the heating unit 31 does not aim to form the positive electrode active material 1, the gap between the heating rollers 31 may not be strictly adjusted.

[0093] In Figure 1 , adjacent heating rollers are arranged facing each other. As can be seen from Figure 1 , for the heating rollers 31 excluding the uppermost upstream and lowermost downstream heating rollers 31, the wrap angles are respectively set. Figure 2 FIG. shows a diagram for explaining the wrap angle. In addition, Figure 3 shows Figure 1 an enlarged view of the heating roller 31.

[0094] The so-called "wrap angle" is, as shown by "x" in Figure 2 , Figure 3 , the central angle of the heating roller 31 obtained based on the range from the start of contact between the positive electrode active material 1 (conveying member 11) and the heating roller 31 until peeling. By setting the wrap angle x for the heating roller 31 as shown in Figure 2 , 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 pulled and moved, heating non-uniformity can be reduced and gas exchange can be promoted. Attachment of the positive electrode active material 1 to the heating roller 31 can also be suppressed. Furthermore, the positive electrode active material 1 sandwiched between the facing heating rollers 31 is fired by being heated from both sides, while the positive electrode active material 1 that is not sandwiched between the heating rollers 31 but is in contact with one heating roller 31 has its contact surface heated and can perform gas exchange from the open surface that is not in contact with the heating roller 31, so that the firing of the positive electrode active material 1 can be promoted. Therefore, by arranging the heating rollers 31 as shown in Figure 1 , Figure 3 , heating (heating and forming) of both sides of the positive electrode active material 1 and heating of one side of the positive electrode active material 1 can be alternately performed, thereby alternately performing heating and high-efficiency gas exchange and promoting firing.

[0095] The wrap angle x of the heating roller 31 can be set to 10° or more, can be set to 20° or more, can be set to 180° or less, and can be set to 90° or less. If the wrap angle of the heating roller is too small, it becomes difficult to straighten the positive electrode active material 1 and move it. If the wrap angle of the heating roller 31 is too large, the positive electrode active material 1 may fall near the vertical direction of the heating roller 31, or the transport thickness may change due to deviation or the like, so there is a possibility that temperature control becomes difficult. The disadvantages in the case of a large wrap angle are particularly likely to occur when the positive electrode active material 1 and the heating roller 31 are not always in contact.

[0096] Furthermore, in Figure 3 , the heating rollers 31 are respectively arranged such that a straight line connecting the centers of adjacent heating rollers 31 coincides with one of the straight lines forming the wrap angle. Thereby, it is possible to always keep the positive electrode active material 1 in contact with the heating roller 31, improve the heating efficiency, and shorten the heating time.

[0097] Moreover, in Figure 3 , wrap angles are set for the heating rollers 31 other than the upstreammost and downstreammost heating rollers 31, but wrap angles can also be set for the upstreammost and downstreammost heating rollers 31.

[0098] The material of the heating unit 31 is not particularly limited. For example, the heating unit 31 can be made of a material having a heat resistance of 1000°C or more. Examples of such materials include inorganic materials such as ceramics and metal materials such as iron.

[0099] The rotation direction of the heating roller can be forward rotation (rotation in the same direction as the transport direction) or reverse rotation (rotation in the direction opposite to the transport direction). The rotation speed of the heating roller is not particularly limited. Those skilled in the art can appropriately select the most suitable rotation direction and rotation speed that combine heat uniformity and economy.

[0100] The surface of the heating roller 31 can have irregularities. By having an irregular shape on the surface of the heating roller 31, it is possible to straighten the positive electrode active material 1 in contact with the heating roller 31 and move it, reduce non-uniform heating, and promote gas exchange. In addition, it is also possible to suppress the adhesion of the positive electrode active material 1 to the heating roller.

[0101] 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 transport member 11 in the width direction. The diameter of the heating roller 31 is appropriately set from the viewpoints of the size of the heating unit 30 and appropriately heating the positive electrode active material 1.

[0102] <Recovery unit 40>

[0103] The recovery unit 40 is a component for recovering the positive electrode active material 2 obtained by the heating unit 30. As Figure 1 shown, when the positive electrode active material 2 is transported while being clamped by the transport member 11, the transport member can be separated in the recovery unit 40 to recover the internal positive electrode active material 2. In addition, the recovered positive electrode active material 2 can also be pulverized. The method for pulverizing the positive electrode active material 2 is not particularly limited, and the positive electrode active material 2 can be pulverized using a hammer or the like after being recovered. In addition, when the positive electrode active material material 1 is in a sheet shape, the obtained positive electrode active material 2 is also in a sheet shape, so it can be easily pulverized. For example, as Figure 1 shown, the positive electrode active material 2 is simply recovered and pulverized.

[0104] 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, by applying vibration in a state where the transport member 11 is turned over, or by blowing air from the surface that has never been in contact with the positive electrode active material 2 ( Figure 1 arrow), the positive electrode active material 2 buried inside can be recovered, and the productivity can be improved. Examples of the device for applying vibration include a vibration knocker. Examples of the device for blowing air include a blower.

[0105] <Positive Electrode Active Material 2>

[0106] The positive electrode active material 2 obtained by the manufacturing device 100 has a composition in which lithium is embedded in 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). In addition, 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), or it can 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).

[0107] In addition, since the positive electrode active material 1 is fired by contact heating, the deviation in the crystallinity of the obtained positive electrode active material 2 is suppressed. The deviation in crystallinity is determined by measuring the crystallite size based on XRD, and the most suitable range of crystallite size (unit: nm) is set in accordance with the battery evaluation results of the positive electrode active material 2. For example, the range of crystallite size can be a range of approximately ±200 nm, a range of ±100 nm, or a range of ±50 nm.

[0108] <Other methods>

[0109] Figure 3 The manufacturing apparatus 200 for a positive electrode active material for a lithium ion secondary battery is shown (in this specification, sometimes referred to as "manufacturing apparatus 200"). The manufacturing apparatus 200 is an apparatus obtained by changing the heating roller 31 of the manufacturing apparatus 100 to a plate-shaped heating unit 131. The material of the plate-shaped heating unit 131 is the same as that of the heating roller 31.

[0110] The plate-shaped heating unit 131 is a plate-shaped heating unit. As Figure 4 described, the paired plate-shaped heating units 131 are arranged in three columns in the transport direction. Moreover, the positive electrode active material 1 is sandwiched and heated by raising and lowering the plate-shaped heating unit 131. At this time, pressure forming can also be performed. Furthermore, during heating, the transport member 11 is temporarily stopped. Even when the plate-shaped heating unit 131 is used as the heating unit in this way, contact heating can be achieved.

[0111] <Supplementary>

[0112] In the manufacturing apparatuses 100 and 200, a plurality of heating units are used, but the manufacturing apparatus of the present disclosure is not limited thereto, and it is sufficient to have at least one heating unit. This is because it is sufficient to arrange them in the number required for firing the positive electrode active material 1. In addition, the shape of the heating unit is not limited to a roll shape and a plate shape, and heating units of various shapes can be adopted. This is because any shape that can achieve contact heating is acceptable.

[0113] [Manufacturing method for positive electrode active material for lithium ion secondary battery]

[0114] Regarding the manufacturing method for the positive electrode active material for a lithium ion secondary battery of the present disclosure, the description will be made while referring to the manufacturing method 1000 for the positive electrode active material for a lithium ion secondary battery as one embodiment (in this specification, sometimes referred to as "manufacturing method 1000").

[0115] Figure 5 The flowchart of the manufacturing method 1000 is shown. As Figure 5As shown, the manufacturing method 1000 includes a positive electrode active material production process S1, a forming process S2, a heating process S3, and a recovery process S4. Furthermore, the forming process S2, the heating process S3, and the recovery process S4 can be implemented using the manufacturing apparatus of the present disclosure.

[0116] <Positive Electrode Active Material Production Process S1>

[0117] The positive electrode active material production process S1 is a process of mixing a lithium compound and a metal compound to obtain a positive electrode active material. Here, since the metal compound, the lithium compound, and the positive electrode active material have been described above, they are omitted here. In addition, since the mixing method has also been described above, it is omitted here.

[0118] <Forming Process S2>

[0119] The forming process S2 is an optional process provided before the heating process S3. The forming process S2 is a process 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-described forming method can be employed.

[0120] <Heating Process S3>

[0121] The heating process S3 is a process of heating (firing) the positive electrode active material. Specifically, the heating process S3 is a process of heating the positive electrode active material by heat conduction. The method of heating the positive electrode active material has been described above, and thus the description is omitted here.

[0122] <Recovery Process S4>

[0123] The recovery process S4 is a process of recovering the positive electrode active material obtained through the heating process S3. The method of recovering the positive electrode active material is not particularly limited. For example, the above-described recovery method can be employed.

[0124] <Other Modes>

[0125] Figure 6Disclosed is a method 2000 for manufacturing a positive electrode active material for a lithium ion secondary battery (hereinafter sometimes referred to as "manufacturing method 2000" in this specification). The manufacturing method 2000 is obtained by providing an oxidative roasting step S5 in the manufacturing method 1000. The oxidative roasting step S5 is a step of heating a metal hydroxide in an oxidative atmosphere before the positive electrode active material production step S1. Since the oxidative roasting method of the metal hydroxide has been described above, it is omitted here. By providing the oxidative roasting step S5, a metal oxide can be obtained. Since the oxidation of the metal hydroxide is an endothermic reaction, if a positive electrode active material containing the metal hydroxide is used in the heating step S3, there is a risk of temperature non-uniformity. Therefore, in the manufacturing method 2000, the oxidative roasting step S5 is provided to oxidize the metal hydroxide in advance. However, since contact heating is employed in the heating step S3, even if a positive electrode active material containing the metal hydroxide is used, the temperature non-uniformity can be reduced.

[0126] Figure 7 Disclosed is a method 3000 for manufacturing a positive electrode active material for a lithium ion secondary battery (hereinafter sometimes referred to as "manufacturing method 3000" in this specification). The manufacturing method 3000 is a method in which a pre-roasting step S6 is provided before the forming step S2. The pre-roasting step S6 is a step of heating the positive electrode active material in an oxidative atmosphere. By the pre-roasting step S6, the metal hydroxide can be oxidized to a metal oxide, and lithium compounds such as lithium hydroxide can be oxidized to lithium oxide. Since such an oxidation reaction is an endothermic reaction, by using the pre-roasting step S6 to complete the oxidation of the positive electrode active material, the temperature non-uniformity of the positive electrode active material can be reduced in the heating step S3, and firing can be performed in a short time. However, since contact heating is employed in the heating step S3, even if the pre-roasting step 6 is not provided, the positive electrode active material containing the metal hydroxide etc. can be appropriately fired to obtain the positive electrode active material.

[0127] The heating temperature of the pre-roasting 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 carried out using a firing apparatus such as a rotary kiln.

[0128] Furthermore, in the manufacturing method of the present disclosure, both the oxidative roasting step S5 and the pre-roasting step S6 can be combined.

[0129] As described above, the manufacturing apparatus and method for the positive electrode active material for a lithium ion secondary battery according to the present disclosure have been described using each embodiment. The present disclosure employs contact heating for heating the positive electrode active material material by heat conduction. The feature of contact heating is that it can heat the contact portion with high efficiency and the temperature non-uniformity of the contact portion is small (high heat uniformity). Therefore, the present disclosure that employs contact heating can reduce the firing time of the positive electrode active material material and can also suppress the deviation of crystallinity. In addition, different from the prior art, the present disclosure can fire the positive electrode active material material with one heating unit (heating step) to obtain the positive electrode active material. Therefore, according to the present disclosure, the productivity of manufacturing the positive electrode active material can be improved. In addition, by shortening the heating time, the equipment can also be miniaturized.

[0130] Industrial applicability

[0131] The positive electrode active material manufactured according to the present disclosure can also be used for the positive electrode of any of a non-aqueous lithium ion secondary battery, an aqueous lithium ion secondary battery, and an all-solid lithium ion secondary battery.

Claims

1. A manufacturing apparatus for a positive electrode active material for a lithium ion secondary battery, comprising a conveying unit and a heating unit. The conveying unit conveys a sheet-like positive electrode active material material containing a lithium compound and the following metal compound, and the metal compound contains at least one metal element selected from nickel, cobalt, and manganese. The conveying unit has a conveying member made of a porous heat-resistant member. The conveying member is a sheet-like member for conveying the positive electrode active material material, and conveys it in a state where the positive electrode active material material is placed thereon. The pore diameter of the pores of the porous heat-resistant member is 0.5 μm or more and 20 μm or less. The heating unit includes a blowing unit that supplies air or oxygen. The heating unit heats the positive electrode active material material. The heating unit has at least one heating unit, and the heating unit indirectly contacts the positive electrode active material through the porous heat-resistant member and heats the positive electrode active material material by heat conduction. The heating unit is a plurality of heating rollers. The heating roller that heats one surface of the positive electrode active material material and the heating roller that heats the other surface of the positive electrode active material material are alternately arranged from the upstream side to the downstream side in the conveying direction. Adjacent heating rollers are arranged facing each other in such a manner as to sandwich the positive electrode active material material. The wrap angle of the heating roller is 20° or more and 90° or less, and the wrap angle is the central angle of the heating roller obtained based on the range from the start of contact between the conveying member and the heating roller until peeling. The plurality of heating rollers are respectively arranged such that a straight line connecting the centers of adjacent heating rollers coincides with one of the straight lines forming the wrap angle.

2. The manufacturing apparatus according to claim 1. The heating unit heats the positive electrode active material material to 700°C or more and 1000°C or less.

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

4. The manufacturing apparatus according to claim 1 or 2. A forming unit for forming the positive electrode active material material into a sheet is provided on the upstream side in the conveying direction with respect to the heating unit.

5. The manufacturing apparatus according to claim 1 or 2. A recovery unit for recovering the positive electrode active material obtained by the heating unit is provided.

6. A manufacturing method for a positive electrode active material for a lithium ion secondary battery, comprising: A positive electrode active material material production step of mixing a lithium compound and the following metal compound to obtain a sheet-like positive electrode active material material, and the metal compound contains at least one metal element selected from nickel, cobalt, and manganese; and A heating step of heating both surfaces of the positive electrode active material material and one surface of the positive electrode active material material alternately by a plurality of heating rollers while conveying the positive electrode active material through a sheet-like conveying member made of a porous heat-resistant member. In the heating step, air or oxygen is supplied from the blowing unit, and the plurality of heating rollers indirectly contact the positive electrode active material through the porous heat-resistant member and heat the positive electrode active material material by heat conduction. The pore diameter of the pores of the porous heat-resistant member is 0.5 μm or more and 20 μm or less. The heating rollers that heat one surface of the positive electrode active material and the heating rollers that heat the other surface of the positive electrode active material are alternately arranged from the upstream side to the downstream side in the conveying direction. Adjacent heating rollers are arranged facing each other with the positive electrode active material sandwiched therebetween. The wrap angle of the heating roller is 20° or more and 90° or less, and the wrap angle is the central angle of the heating roller obtained based on the range from the start of contact between the conveying member and the heating roller until peeling. The plurality of heating rollers are respectively arranged such that a straight line connecting the centers of adjacent heating rollers coincides with one of the straight lines forming the wrap angle.

7. The manufacturing method according to claim 6. In the heating step, the positive electrode active material is heated to 700 °C or more and 1000 °C or less.

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

9. The manufacturing method according to claim 6 or 7. Before the heating step, a forming step of forming the positive electrode active material into a sheet shape is provided.

10. The manufacturing method according to claim 6 or 7. A recovery step of recovering the positive electrode active material obtained through the heating step is provided.

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