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 secondary battery includes conveying means 10 for conveying a positive electrode active substance material 1 containing a metal compound 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 heating roller 31 that heats the positive electrode active substance material 1 by thermal conduction. The at least one heating roller 31 has a holding angle of more than 180° and less than or equal to 360°.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 producing a positive electrode active material for a lithium ion secondary battery, the apparatus 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, the heating unit having at least one heating roller for heating the positive electrode active material by thermal conduction, the wrap angle of the at least one heating roller being greater than 180° and equal to or less than 360°.

[0011] The manufacturing apparatus may be in the following form: That is, the manufacturing apparatus may have a plurality of heating rollers, in which heating rollers for heating one surface of the positive electrode active material and heating rollers 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 opposite to each other so as to sandwich the positive electrode active material.

[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. In the above-mentioned manufacturing apparatus, the heating section may heat the positive electrode active material in an oxidizing atmosphere.

[0013] In the above-mentioned production apparatus, the transport means may have a transport member made of a porous heat-resistant member, and the heating roller may heat the positive electrode active material through the 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, and 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, 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, in which the heating step uses at least one heating roller to heat the positive electrode active material by thermal conduction while transporting the positive electrode active material, and the wrap angle of the at least one heating roller is more than 180° and not more than 360°.

[0016] In the heating step of the above-mentioned production method, both sides of the positive electrode active material and one side of the positive electrode active material may be heated alternately by a heating roller.

[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. Furthermore, in the above manufacturing method, the heating step may heat the positive electrode active material through a porous heat-resistant member.

[0018] The manufacturing method may include a forming step of forming the positive electrode active material into a sheet prior to the heating step. The manufacturing method may also include a recovery step of recovering the positive electrode active material obtained by the heating step. Effect of the Invention

[0019] According to the present disclosure, it is possible to improve the production productivity of the positive electrode active material. [Brief description of the drawings]

[0020] [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] FIG. 2 is a diagram for explaining a embrace angle x. [Diagram 3] 3 is an enlarged view of the heating roller 31 and the touch roll 32. FIG. [Figure 4] 1 is a flowchart of a method 1000 for producing a positive electrode active material for a lithium ion secondary battery. [Diagram 5] 2 is a flowchart of a method 2000 for producing a positive electrode active material for a lithium ion secondary battery. [Figure 6] 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

[0021] [Production 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 a manufacturing apparatus 100 for a positive electrode active material for a lithium ion secondary battery (sometimes referred to as "manufacturing apparatus 100" in this specification) which is one embodiment. A schematic diagram of the manufacturing apparatus 100 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.

[0022] 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.

[0023] <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.

[0024] 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.

[0025] (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.

[0026] 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).

[0027] 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.

[0028] 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).

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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 3 The 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.

[0033] 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.

[0034] 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.

[0035] 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 "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.

[0036] 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.

[0037] (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.

[0038] 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.

[0039] 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.

[0040] (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.

[0041] 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.

[0042] 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.

[0043] <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.

[0044] (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 with the positive electrode active material 1 placed thereon, it needs to be disposed on the lower surface of the positive electrode active material 1. Alternatively, as illustrated in FIG. 1, the transport member 11 may also be disposed on the upper surface of the positive electrode active material 1. That is, the positive electrode active material 1 may be transported while being sandwiched between the transport members 11.

[0045] 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 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, when the upper and lower surfaces of the positive electrode active material 1 are heated, the positive electrode active material 1 may be conveyed by being sandwiched between the conveying members 11.

[0046] 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.

[0047] 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.

[0048] 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).

[0049] <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.

[0050] 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.

[0051] 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.

[0052] <Heating section 30> The heating section 30 heats (calcines) the positive electrode active material 1. As shown in Fig. 1, the heating section 30 is a rectangular housing and includes six heating rollers 31 therein. The heating section 30 also includes touch rolls 32 at positions adjacent to the heating rollers 31 on the upstream and downstream sides in the conveying direction.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] (heat roller 31) The heating roller 31 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, and means that the heating roller 31 is brought into direct or indirect contact with the positive electrode active material 1 to heat the positive electrode active material 1. "Indirectly" means that the heating roller 31 is brought into contact with the positive electrode active material 1 through another member to heat the positive electrode active material 1. In FIG. 1, the heating roller 31 is brought into contact with the positive electrode active material 1 through the conveying member 11 to heat the positive electrode active material 1. In addition, the heating roller 31 may be brought into contact with the positive electrode active material 1 through a member other than the conveying member 11, or through the conveying member 11 and another member to heat the positive electrode active material 1. In this specification, unless otherwise specified, "direct or indirect contact" may be simply expressed as "contact".

[0057] 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.

[0058] Furthermore, by employing the heating rollers 31, the positive electrode active material 1 can be heated while being transported, making it possible to continuously produce the positive electrode active material 2.

[0059] 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. As shown in FIG. 1, the heating rollers for heating one side (e.g., the upper side) of the positive electrode active material 1 and the heating rollers 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.

[0060] 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.

[0061] The heating rollers 31 are disposed opposite each other and are set at a predetermined wrap angle. A diagram for explaining the wrap angle is shown in Fig. 2. Fig. 3 shows an enlarged view of the heating roller 31 and the touch roll 32 in Fig. 1.

[0062] The "hugging angle" is the central angle of the heating roller 31, as shown by "x" in Fig. 2 and Fig. 3, 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. 2, by setting the hugging 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 can be 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 3, 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.

[0063] The embrace angle x of the heating roller 31 is more than 180° and less than 360°. By making the embrace angle x more than 180°, the positive electrode active material 1 is transported in the height direction, so that the rolling of the positive electrode active material 1 during transport is promoted, the thermal uniformity is improved, and gas exchange is promoted. This suppresses uneven oxidation of the positive electrode active material 2, which is the product, and improves the quality. In addition, since the contact time between the heating roller 31 and the positive electrode active material 1 can be extended, the equipment can be made smaller. Therefore, compared to the case where the embrace angle x is 180° or less, the manufacturing productivity of the positive electrode active material 2 can be improved. The embrace angle x may be 210° or more, 240° or more, 270° or more, 300° or more, less than 360°, 350° or less, or 330° or less.

[0064] The wrap angle x can be set by the arrangement of the heating roller 31 and the touch roll 32. In Fig. 1 and Fig. 3, the heating rollers 31 are arranged so as to have a predetermined wrap angle x. By arranging them in this manner, the wrap angle x of the heating rollers 31 can be set to a desired value, except for the most upstream and most downstream heating rollers 31. Furthermore, the touch rolls 32 are arranged at positions adjacent to the upstream and downstream heating rollers 31 in the conveying direction. This allows the wrap angle of the most upstream and most downstream heating rollers 31 to be set to a desired value.

[0065] 3, the heating rollers 31 are arranged so that a straight line connecting the centers of adjacent heating rollers 31 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 31, improving the heating efficiency and shortening the heating time.

[0066] 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.

[0067] The rotation direction of the heating roller 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 roll 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.

[0068] The surface of the heating roller 31 may have an uneven surface. 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.

[0069] 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.

[0070] (Touch Roll 32) The touch rolls 32 are disposed at positions adjacent to the heating rollers 31 on the upstream and downstream sides in the transport direction. As described above, the touch rolls 32 are used to set the wrap angle between the adjacent heating rollers 31. The touch rolls 32 may be disposed at positions facing the adjacent heating rollers 31.

[0071] However, the touch roll 32 is an optional member in the manufacturing apparatus 100. Also, the number of touch rolls 32 may be at least one. Furthermore, the position of the touch roll 32 is not particularly limited, and it may be disposed at a position adjacent to the heating roller 31 that sets the wrap angle.

[0072] 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 31. The length of the touch roll 32 in the width direction is not particularly limited, but may be set to, for example, the same length as the length of the transport member 11 in the width direction. The diameter of the touch roll 32 can be appropriately set based on the size of the heating section 30 and the wrap angle of the heating roller 31.

[0073] <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.

[0074] 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.

[0075] <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 Co y 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).

[0076] 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.

[0077] <Supplementary Information> Although a plurality of heating rollers 31 are used in the manufacturing apparatus 100, the manufacturing apparatus of the present disclosure is not limited to this, and may have at least one heating roller. This is because the number of heating rollers necessary for firing the positive electrode active material 1 may be installed. In addition, in the manufacturing apparatus of the present disclosure, the wrap angle of at least one heating roller may be more than 180° and less than 360°C. This provides a productivity improvement effect. However, the more the number of heating rollers with wrap angles of more than 180° and less than 360°C increases, the more the productivity improvement effect improves. Therefore, the wrap angles of all heating rollers may be set to more than 180° and less than 360°C.

[0078] [Method of manufacturing positive electrode active material for lithium ion secondary batteries] The manufacturing method of the present disclosure for a positive electrode active material for a lithium ion secondary battery will be described with reference to a manufacturing method 1000 for a positive electrode active material for a lithium ion secondary battery (sometimes referred to as "manufacturing method 1000" in this specification) which is one embodiment.

[0079] A flowchart of the manufacturing method 1000 is shown in Fig. 4. As shown in Fig. 4, the manufacturing method 1000 includes a positive electrode active material preparation step S1, a molding step S2, a heating step S3, and a recovery step S4. The molding step S2, the heating step S3, and the recovery step S4 can be performed by a manufacturing apparatus according to the present disclosure.

[0080] <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.

[0081] <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.

[0082] <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.

[0083] <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.

[0084] <Other forms> FIG. 5 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). 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 in 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, and oxidizes 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.

[0085] FIG. 6 shows a manufacturing method 3000 of a positive electrode active material for a lithium ion secondary battery (sometimes referred to as "manufacturing method 3000" in this specification). In the manufacturing method 3000, a calcination step S6 is provided 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, by completing the oxidation of the positive electrode active material in the calcination step S6, it is possible to reduce the temperature unevenness of the positive electrode active material in the heating step S3 and to perform firing in a short time. However, since the heating step S3 employs contact heating, it is possible to appropriately fire the positive electrode active material containing metal hydroxides and the like and obtain the positive electrode active material without providing the calcination step 2.

[0086] 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.

[0087] In the manufacturing method of the present disclosure, both the oxidizing roasting step S5 and the calcining step S6 may be combined.

[0088] 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 by thermal conduction. Contact heating is characterized by being able to efficiently heat the contact area and having small temperature unevenness at the contact area (high thermal uniformity). 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 in one heating section (heating step) to obtain the positive electrode active material. Furthermore, the shortening of the heating time can also reduce the size of the equipment.

[0089] In addition, in the present disclosure, the embrace angle x of at least one heating roller is set to be more than 180° and less than or equal to 360°. As a result, the positive electrode active material is transported in the height direction, and the rolling of the positive electrode active material during transportation is promoted, improving the thermal uniformity and promoting gas exchange. This suppresses uneven oxidation of the positive electrode active material, which is the product, and improves the quality. In addition, since the contact time between the heating roller and the positive electrode active material can be extended, the equipment can be further miniaturized.

[0090] As described above, according to the present disclosure, it is possible to improve the production productivity of the positive electrode active material. [Industrial Applicability]

[0091] 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]

[0092] 1 Cathode active material 2 Cathode active material 10. Means of transportation 11 Transporting member 20 Forming means 30 Heating section 31 Heating roller 32 Touch Roll 40 Collection Department 41 Roller 100 Apparatus for manufacturing positive electrode active material for lithium ion secondary batteries

Claims

1. A transport means for transporting 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 a plurality of heating rollers that heat the positive electrode active material by thermal conduction, At least one of the heating rollers has a wrap angle of more than 180° and not more than 360°; 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 disposed opposite each other so as to sandwich the positive electrode active material therebetween. Manufacturing equipment for positive electrode active materials for lithium-ion secondary batteries.

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

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

4. The conveying means has a conveying member made of a porous heat-resistant material, 4. The manufacturing apparatus according to claim 1, wherein the heating roller heats the positive electrode active material through the porous heat-resistant member.

5. The manufacturing apparatus according to any one of claims 1 to 4, further comprising a forming means for forming the positive electrode active material into a sheet, the forming means being disposed upstream of the heating section in a conveying direction.

6. The manufacturing apparatus according to any one of claims 1 to 5, further comprising a recovery section that recovers the positive electrode active material obtained by the heating section.

7. 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; A heating step of heating the positive electrode active material, The heating step includes heating the positive electrode active material by thermal conduction while transporting the positive electrode active material using at least one heating roller; At least one of the heating rollers has a wrap angle of more than 180° and not more than 360°; In the heating step, both sides of the positive electrode active material and one side of the positive electrode active material are alternately heated by the heating roller. A method for producing a positive electrode active material for a lithium ion secondary battery.

8. The method according to claim 7 , wherein the heating step heats the positive electrode active material to 700° C. or more and 1000° C. or less.

9. The method according to claim 7 or 8, wherein the heating step heats the positive electrode active material in an oxidizing atmosphere.

10. The method according to any one of claims 7 to 9, wherein the heating step heats the positive electrode active material through a porous heat-resistant member.

11. The method according to any one of claims 7 to 10, further comprising a forming step of forming the positive electrode active material into a sheet prior to the heating step.

12. The method according to any one of claims 7 to 11, further comprising a recovery step of recovering the positive electrode active material obtained by the heating step.

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