Method for producing positive electrode active material for nonaqueous electrolyte secondary battery

Abstract

This invention provides a method for manufacturing a positive electrode active material for non-aqueous electrolyte secondary batteries. By including at least a spraying / mixing step of preparing a mixture by mixing a precursor compound of the positive electrode active material with a lithium compound and spraying the mixture with a spray agent containing at least one element, it is possible to manufacture a positive electrode active material for non-aqueous electrolyte secondary batteries without reducing production efficiency and without adversely affecting the battery characteristics of the non-aqueous electrolyte secondary batteries.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a positive electrode active material for non-aqueous electrolyte secondary batteries. This method can manufacture a positive electrode active material that can improve the battery characteristics of non-aqueous electrolyte secondary batteries without reducing production efficiency. Background Technology

[0002] In recent years, the widespread adoption of portable and wireless electronic devices such as mobile phones and laptops has led to the rapid development of non-aqueous secondary batteries, which serve as the power source for these devices. These batteries are small, lightweight, and possess high energy density. Among them, lithium-ion secondary batteries, which use materials such as lithium nickel oxide as their positive electrode, are widely used and have the advantage of large charge and discharge capacity.

[0003] Therefore, research on solid solutions of nickel (Ni) and other transition metals M with excellent versatility, namely layered rock salt oxide system positive electrode active materials for lithium-ion secondary batteries (basic composition: Li(NiM)O2), is prevalent.

[0004] Among these layered rock salt oxide-based cathode active materials, in addition to commonly used cobalt (Co), manganese (Mn), magnesium (Mg), and aluminum (Al), cathode active materials containing tungsten (W) as a transition metal have attracted attention. Since the presence of tungsten on the particle surface and particle interface of the cathode active material can improve electronic conductivity, this cathode active material is being used to manufacture higher-performance lithium-ion secondary batteries.

[0005] In particular, when adding metal elements such as tungsten, the focus is on uniformly distributing smaller metal elements on the surface of the positive electrode active material particles.

[0006] For example, Patent Documents 1 and 2 describe a method for manufacturing a layered rock salt oxide-based positive electrode active material. In this method, before the calcination process for obtaining the positive electrode active material, a layered rock salt oxide-based positive electrode active material is manufactured by adding a tungsten compound when mixing a composite oxide or composite hydroxide composed of other transition metal compounds with a lithium compound, or when mixing other transition metal compounds with a lithium compound.

[0007] In addition, patent documents 3 and 4 describe a method for manufacturing a layered rock salt oxide-based positive electrode active material. In this method, before the calcination process, a solution of a compound containing lithium and tungsten (hereinafter referred to as Li-W solution) is sprayed onto the precursor of the positive electrode active material to manufacture the layered rock salt oxide-based positive electrode active material.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2014-197556

[0011] Patent Document 2: Japanese Patent Application Publication No. 2011-228292

[0012] Patent Document 3: Japanese Patent Application Publication No. 2019-040675

[0013] Patent Document 4: International Publication No. 2018 / 105481 Summary of the Invention

[0014] -The problem the invention aims to solve-

[0015] However, the methods described in Patent Documents 1 and 2 have the following problems: the tungsten concentration is uneven when adding tungsten compounds, resulting in foreign matter from tungsten in the obtained positive electrode active material, or the particle growth inhibition effect of the positive electrode active material is deviated due to the local presence of tungsten, thus adversely affecting the battery characteristics.

[0016] In addition, the methods described in Patent Documents 3 and 4 have the following problems: after manufacturing the precursor and before mixing it with the lithium compound, an additional step of spraying the precursor of the positive electrode active material with Li-W solution is added, which greatly reduces the production efficiency.

[0017] The present invention was made in view of the above-mentioned problems, and its object is to provide a method for manufacturing positive electrode active material without adversely affecting battery characteristics without reducing production efficiency.

[0018] -Solutions for solving the problem-

[0019] To achieve the above objectives, the method for manufacturing the positive electrode active material of the present invention is configured such that, while mixing the precursor of the positive electrode active material with a lithium compound, the precursor and the lithium compound are uniformly mixed by spraying an aerosol containing an element such as tungsten or zirconium.

[0020] The method for manufacturing the positive electrode active material for non-aqueous electrolyte secondary batteries according to the present invention is characterized by comprising at least:

[0021] The spray / mixing process involves mixing a precursor compound of a positive electrode active material with a lithium compound to prepare a mixture, and then spraying the mixture with a spray agent containing at least one element.

[0022] -The Effects of the Invention-

[0023] In the manufacturing method of the present invention, the mixing of the precursor compound and the lithium compound is carried out simultaneously with the addition of a spray agent containing at least one element. The positive electrode active material obtained by this manufacturing method is more uniformly coated with tiny particles added to the surface of its particles. Using this positive electrode active material in a non-aqueous electrolyte secondary battery not only does not adversely affect battery characteristics, but may even improve them. Furthermore, according to the manufacturing method of the present invention, such a positive electrode active material can be easily manufactured without reducing production efficiency. Attached Figure Description

[0024] Figure 1 This is a flowchart (flow α) illustrating one embodiment of the method for manufacturing the positive electrode active material for a non-aqueous electrolyte secondary battery according to the present invention.

[0025] Figure 2 This is a flowchart (flow β) illustrating one embodiment of the method for manufacturing the positive electrode active material for a non-aqueous electrolyte secondary battery according to the present invention.

[0026] Figure 3 This is a flowchart (flowchart γ) illustrating one embodiment of the method for manufacturing the positive electrode active material for a non-aqueous electrolyte secondary battery according to the present invention.

[0027] Figure 4 This is a flowchart (flow δ) illustrating an example of a conventional method for manufacturing positive electrode active materials.

[0028] Figure 5 This is a flowchart (flow ε) illustrating an example of a conventional method for manufacturing positive electrode active materials.

[0029] Figure 6 This is a flowchart (flow ζ) illustrating an example of a conventional method for manufacturing positive electrode active materials. Detailed Implementation

[0030] The embodiments of the present invention will be described below. The following description of preferred embodiments is merely illustrative and is not intended to limit the present invention, its applicable methods, or its uses.

[0031] The method for manufacturing the positive electrode active material for non-aqueous electrolyte secondary batteries according to the present invention includes at least the following steps: a spraying / mixing step that simultaneously prepares a mixture by mixing a precursor compound of the positive electrode active material with a lithium compound, and spraying the mixture with a spray agent containing at least one element.

[0032] In the manufacturing method of the present invention, the precursor compound of the positive electrode active material used in the above-described spray / mixing process can be a precursor compound synthesized by conventional methods.

[0033] The aforementioned precursor compound is preferably a composite hydroxide or composite oxide containing at least one element other than lithium (Li) according to the composition of the target positive electrode active material. This at least one element other than Li is not particularly limited, as long as it can constitute the positive electrode active material; examples include: nickel (Ni), cobalt (Co), manganese (Mn), magnesium (Mg), aluminum (Al), molybdenum (Mo), niobium (Nb), vanadium (V), titanium (Ti), chromium (Cr), calcium (Ca), zinc (Zn), iron (Fe), gallium (Ga), strontium (Sr), yttrium (Y), ruthenium (Ru), indium (In), tin (Sn), tantalum (Ta), bismuth (Bi), tungsten (W), zirconium (Zr), boron (B), phosphorus (P), etc. Preferably, it is a composite hydroxide or composite oxide containing at least Ni, more preferably a so-called ternary system composed of Ni, Co, and Mn, and particularly preferably a composite hydroxide or composite oxide in which the Ni content is 30 mol% to 70 mol% relative to the total amount of Ni, Co, and Mn.

[0034] The manufacturing method of the above-mentioned composite hydroxide or composite oxide is not particularly limited. For example, the following method can be used: According to the composition of the target positive electrode active material, prepare an aqueous solution of at least one element other than Li or its compound, adjust the mixing ratio as needed, and drop it into a reaction tank with one or more alkaline aqueous solutions such as sodium hydroxide solution or ammonia solution as the mother liquor while stirring. At the same time, sodium hydroxide is added to control the pH value in an appropriate range of, for example, about 11 to about 13 to carry out a crystallization reaction. Through the crystallization reaction, a hydroxide or oxide with a secondary particle shape formed by the aggregation of primary particles co-precipitated and agglomerated is obtained.

[0035] It should be noted that the precursor compound obtained by the wet reaction as described above can also be washed, dehydrated, and then dried. This washing process removes impurities such as sulfate, carbonate, and sodium that entered the aggregated particles or adhered to the surface during the reaction. Furthermore, this drying process can be carried out in an oxidizing atmosphere, for example, at approximately 50°C to approximately 250°C.

[0036] Alternatively, the precursor compound can be oxidized in an oxidizing atmosphere, for example, at about 300°C to about 800°C. This oxidation treatment oxidizes the precursor compound and removes the impurities, thereby increasing the purity of the precursor compound. Furthermore, it increases the bulk density, thus improving production efficiency.

[0037] The main feature of the manufacturing method of the present invention is that, prior to firing (hereinafter also referred to as main firing), a spray agent is sprayed while, for example, the precursor compound synthesized as described above is mixed with a lithium compound.

[0038] Conventionally, by using elements such as tungsten (W) and zirconium (Zr) to coat the surface of positive electrode active material particles in an island-like manner, so that the tungsten (W) and zirconium (Zr) are uniformly present in at least a portion of the particle surface, it is possible to improve battery characteristics such as input / output characteristics and cycle characteristics when manufacturing a secondary battery. With this in mind, various methods have been attempted to ensure that these elements are present on the secondary particle surface and the primary particle surface layer, including the interface, of the positive electrode active material. However, even with compounds in powder form that directly add these elements, it is difficult to obtain a positive electrode active material with these elements more uniformly coated and present on the particle surface. Furthermore, even if such positive electrode active material particles can be obtained, as shown in the techniques described in Patent Documents 1-4, the manufacturing methods increase costs and impair production efficiency.

[0039] However, as shown in the manufacturing method of the present invention, the element to be present on the particle surface or particle interface of the positive electrode active material is made into a spray, and the positive electrode active material particles uniformly coated with the target element can be easily obtained by spraying the spray while the precursor compound and lithium compound are mixed. Furthermore, the mixing time is not significantly affected, thus enabling the production of the positive electrode active material very efficiently and easily without reducing production efficiency.

[0040] <Operating conditions for spraying / mixing processes>

[0041] The operating conditions for the spraying / mixing process are described in detail below.

[0042] There are no particular limitations on the lithium compound used to mix with the precursor compound, and various lithium salts can be used. Examples of such lithium compounds include: lithium carbonate, lithium hydroxide monohydrate, anhydrous lithium hydroxide, lithium nitrate, lithium acetate, lithium bromide, lithium chloride, lithium citrate, lithium fluoride, lithium iodide, lithium lactate, lithium oxalate, lithium phosphate, lithium pyruvate, lithium sulfate, and lithium oxide. In this invention, lithium carbonate, lithium hydroxide monohydrate, and anhydrous lithium hydroxide are preferred.

[0043] Among the lithium compounds mentioned above, lithium hydroxide is preferred when the sprayed material is calcined at low temperature. However, since a large amount of water is generated, anhydrous lithium hydroxide is preferred from the viewpoint of improving productivity.

[0044] It should be noted that, in this specification, the mixture of the precursor compound and the lithium compound in the form of a spray aerosol is referred to as the sprayed material.

[0045] The spray agent for spraying the mixture of precursor compound and lithium compound only needs to contain at least one element that is to be present in the crystalline structure of the positive electrode active material, or at the particle surface or particle interface of the positive electrode active material.

[0046] There are no particular limitations on the elements contained in the spray, as long as they can form positive electrode active materials. Examples include: Ni, Co, Mn, Mg, Al, Mo, Nb, W, Zr, B, P, V, Ti, Cr, Ca, Zn, Fe, Ga, Sr, Y, Ru, In, Sn, Ta, Bi, etc.

[0047] When using a spray containing at least one element selected from Mn, Al, Mg, and Ti, the firing process allows this element to be more uniformly distributed, particularly within the crystalline structure of the particle surface, thereby stabilizing the crystalline structure. As a result, the obtained positive electrode active material exhibits improved cycle characteristics and high-temperature storage performance when used in the fabrication of non-aqueous electrolyte secondary batteries.

[0048] Furthermore, when using a spray containing at least one element selected from W, Zr, Nb, B, P, and Mo, the element can be more uniformly distributed on the particle surface, primarily in an island-like or coated state, thereby enabling the particle surface portion to have low resistance. As a result, the obtained positive electrode active material can further improve battery characteristics such as input / output characteristics and cycle performance when used in non-aqueous electrolyte secondary batteries.

[0049] The spray can be any form that allows the spraying of a mixture of precursor compound and lithium compound; there are no particular limitations. Examples include aqueous solutions, solutions containing organic solvents, and suspensions containing water and / or organic solvents. Furthermore, the form of the spray can be appropriately determined based on the type of at least one element contained within it.

[0050] For example, when the elements are at least W, B, P, etc., the spray is preferably an aqueous solution containing at least W, B, P, etc., and when the elements are at least Zr, Nb, Mo, etc., the spray is preferably a suspension containing at least Zr, Nb, Mo, etc.

[0051] Furthermore, for example, when the elements are at least Mn, Al, Mg, Ti, etc., the spray can be a solution containing at least Mn, Al, Mg, Ti, etc., or a suspension containing at least Mn, Al, Mg, Ti, etc. Examples of such solutions include sulfate aqueous solutions and carbonate aqueous solutions, and examples of such suspensions include suspensions of compound powders with an average secondary particle size of at least submicron, approximately 5 nm to approximately 800 nm, based on a volumetric particle size distribution.

[0052] It should be noted that in this specification, the average secondary particle size (D50) is: a value calculated based on volume, measured using a laser-type particle size distribution measuring device (Microtrack HRA, manufactured by NIKKISO CO., LTD) and employing the wet laser method, based on a specified refractive index corresponding to the powder of the compound to be measured.

[0053] When the element contained in the spray is W, the compound is not particularly limited, and examples include tungsten oxide, sodium tungstate, ammonium paratungstate, tungsten hexacarbonyl, and tungsten sulfide, among which tungsten oxide is preferred. Furthermore, the amount of W in the spray relative to the total amount of metal elements in the precursor compound (e.g., the total amount of Ni, Co, and Mn in the ternary precursor compound composed of Ni, Co, and Mn shown in the examples) is preferably 0.3 mol% to 1.5 mol%, more preferably 0.3 mol% to 1.3 mol%. The spray used is preferably an aqueous solution.

[0054] When the element contained in the spray is Zr, the compound is not particularly limited, and examples include zirconium oxide, stabilized zirconium (yttrium stable zirconium (YSZ)), lithium zirconate, zirconium chloride, zirconium tungstate, etc., with zirconium oxide being preferred. Furthermore, the amount of Zr in the spray relative to the total amount of metal elements in the precursor compound (e.g., the total amount of Ni, Co, and Mn in the ternary precursor compound composed of Ni, Co, and Mn shown in the examples) is preferably 0.3 mol% to 1.5 mol%. The spray used is preferably a suspension of pure water.

[0055] When the element contained in the spray is Nb, the compound is not particularly limited, and examples include niobium oxide, niobium hydroxide, and lithium niobate, with niobium oxide being preferred. Furthermore, the amount of Nb in the spray relative to the total amount of metal elements in the precursor compound (e.g., the total amount of Ni, Co, and Mn in the ternary precursor compound composed of Ni, Co, and Mn shown in the examples) is preferably 0.3 mol% to 1.5 mol%. The spray used is preferably a suspension of pure water.

[0056] When the element contained in the spray is B, the compound is not particularly limited, and examples include boron oxide, boric acid, and lithium tetraborate, with boric acid being preferred. Furthermore, the amount of B in the spray relative to the total amount of metal elements in the precursor compound (for example, the total amount of Ni, Co, and Mn in the ternary precursor compound composed of Ni, Co, and Mn shown in the examples) is preferably 0.3 mol% to 1.5 mol%. The spray used is preferably an aqueous solution.

[0057] There are no particular limitations on the preparation method of the spray. At least one element can be selected according to the composition of the target positive electrode active material, and the amount of each element can be adjusted appropriately. For example, the method of mixing these elements or compounds of elements (hereinafter referred to as element compounds) with an appropriate amount of solvent such as water can be used. In addition, for example, the method of mixing an appropriate amount of acidic compound such as oxalic acid, an appropriate amount of alkaline compound such as sodium hydroxide or lithium compound, and an appropriate amount of solvent such as water can also be used.

[0058] In particular, when the alkaline compound is a lithium compound, for example, a lithium compound exemplified as a lithium compound mixed with the aforementioned precursor compound can be used. In this case, it is preferable to determine the amount of lithium compound by considering the state of the added elements in the final positive electrode active material and the reaction between Li in the lithium compound and the added elements. For example, according to Example 1 of the present invention described later, by adjusting the molar ratio of Li in the spray to the added W to 4:1, a compound with the composition Li4WO5 can be used for coating when preparing the positive electrode active material.

[0059] From the viewpoint of not altering the properties of the precursor compounds and lithium compounds in the mixture, and from the viewpoint of suppressing corrosion of containers storing the mixture and / or the sprayed material, such as sprayers / mixers, the pH value of the spray is preferably adjusted to about 4 to about 12, more preferably to about 5 to about 11.

[0060] Furthermore, when at least one element contained in the spray is Zr, Nb, etc., as described above, solutions of Zr and Nb, such as aqueous solutions of zirconium sulfate or organic solutions formed by dissolving Zr and Nb in organic solvents, can be used as the spray. For example, suspensions containing at least Zr and Nb can also be used. When using a suspension as the spray to obtain the positive electrode active material, the advantages are as follows: a superior non-aqueous electrolyte secondary battery with a more sufficient initial discharge capacity and higher output can be manufactured from this positive electrode active material.

[0061] When using the aforementioned Zr-containing suspension, the preferred type of Zr is an inorganic compound such as ZrO2 or YSZ, with ZrO2 being particularly preferred. Furthermore, the particle size of the Zr compound in the suspension is only required to prevent clogging when sprayed as a spray agent; for example, a submicron level average secondary particle size of a few micrometers or less based on volumetric particle size distribution measurement is preferred, and more preferably 5 nm to 800 nm. While a small average secondary particle size typically makes powder mixing difficult due to its flowability, its use in the spray / mixing process of this invention allows for more uniform coating of the positive electrode active material particles with Zr compounds such as ZrO2. As a result, the effect of the small Zr compound particles can be more fully obtained, thereby further improving output and lifespan characteristics when manufacturing non-aqueous electrolyte secondary batteries.

[0062] In the preparation of the aerosol, the amount of the added elemental compound is approximately 5 wt% to approximately 40 wt% of the total aerosol volume. The more elemental compound added, the more elements can be sprayed with less aerosol, for example. Furthermore, it is preferable to consider the correlation with the composition of the precursor compound, the average secondary particle size, the specific surface area obtained by the BET method (hereinafter referred to as BET specific surface area), etc. By setting the amount of the added elemental compound within an optimal range based on these factors, the necessary amount of elements can be sprayed onto the mixture more uniformly with less aerosol. If too much elemental compound is added, it may not dissolve during aerosol preparation, and local precipitation may occur during spraying. If too little elemental compound is added, segregation may occur in the sprayed material, thereby impairing uniformity. In this invention, the amount of elemental compound in the aerosol is preferably 8 wt% to 35 wt%, more preferably 8 wt% to 33 wt%. It should be noted that, in the case of a precursor compound used in particular, such as a ternary precursor compound consisting of Ni, Co and Mn as shown in the examples, containing at least Ni, and being a small-particle-size precursor compound with an average secondary particle size of 5.5 μm or less, or even 2 μm to 5 μm, as described below, the amount of the elemental compound in the spray is preferably set within this range.

[0063] In this invention, the optimal width of the relationship between the amount of aerosol and spraying time (the amount of aerosol sprayed per minute) is considered to be influenced by factors such as the composition of the precursor compound, the average secondary particle size, and the BET specific surface area. In particular, this is especially true when using precursor compounds with an average secondary particle size of 5.5 μm or less, or even 2 μm to 5 μm, or when using a BET specific surface area of ​​10 m². 2In the case of precursor compounds of / g or above, the above-mentioned optimal width is considered to be greatly affected. By controlling this condition, the spray can be sprayed evenly onto the mixture without impairing flowability, thus improving the productivity of the positive electrode active material.

[0064] There is no particular limitation on the spray pressure when spraying a mixture of precursor compound and lithium compound, as long as it is within the range that allows for spraying and full addition to the mixture. However, if the spray pressure is too low, spraying may not be completed within the predetermined mixing time. Additionally, if the droplet diameter is too large, the mixture may not be uniformly coated. Conversely, if the spray pressure is too high, the droplet diameter may be too small, failing to fully coat the mixture. Furthermore, nozzle clogging may occur.

[0065] There are no particular limitations on the spraying method when spraying a mixture of precursor compound and lithium compound, as long as it is a method that can uniformly and thoroughly spray the mixture, such as a sprayer / mixer. Furthermore, various sprayers, nozzles, etc., can be listed as spraying devices.

[0066] When spraying the mixture of precursor compound and lithium compound, the spraying time is preferably approximately the same as the time to obtain the mixture, and more preferably shorter than the time to obtain the mixture. By completing the spraying in a shorter time than the time to obtain the mixture, the sprayed aerosol can be thoroughly agitated, thereby further improving uniformity.

[0067] It should be noted that the spraying time of the aerosol is not significantly different from the conventional method where the elements to be coated on the surface of the positive electrode active material particles are added directly without being sprayed, as long as the time does not reduce production efficiency. Furthermore, this spraying time can be adjusted by appropriately changing the spray volume and spray pressure of the aerosol to ensure uniform and thorough spraying.

[0068] Preferably, in the manufacturing method of the present invention, during the above-described spraying / mixing step, the pressure inside the container holding at least one of the mixture and the sprayed material (hereinafter referred to as the mixture and / or the sprayed material) is less than atmospheric pressure, i.e., the spraying / mixing step is performed under reduced pressure. Therefore, by performing the spraying / mixing step under reduced pressure in a container holding the mixture and / or the sprayed material, such as a spraying / mixing machine, even without additional steps such as the drying step described later, the solvent contained in the spray can be easily removed according to the particle size of the target positive electrode active material without impairing the flowability of the mixture and / or the sprayed material, thereby further improving productivity.

[0069] Furthermore, in the manufacturing method of the present invention, by performing the above-mentioned spraying / mixing process under stirring and reduced pressure, the removal of solvent contained in the spray can be promoted.

[0070] Previously, when mixing lightweight and bulky raw materials such as lithium compounds under reduced pressure, the following concerns arose: lithium compounds could scatter into the pump section used for depressurization, causing deviations in the mixing ratio of the target precursor compound and the lithium compound. However, in this invention, it has been discovered that, in addition to setting the conditions at the start of mixing and operating under reduced pressure, these concerns can also be eliminated by controlling the spray of the aerosol.

[0071] When applying reduced pressure or agitated reduced pressure as described above, the vacuum level (gauge pressure) inside the container holding the mixture and / or the aerosol is preferably -95 kPa or higher and less than 0 kPa, more preferably -95 kPa to -20 kPa, and particularly preferably -95 kPa to -30 kPa. If the vacuum level inside the container holding the mixture and / or the aerosol is less than the lower limit mentioned above, the aerosol droplets may be drawn into the pressure reducing pump. By ensuring that the vacuum level inside the container holding the mixture and / or the aerosol is less than 0 kPa, and further below the upper limit mentioned above, the effects of applying reduced pressure or agitated reduced pressure can be obtained, easily shortening the drying time and thereby improving productivity.

[0072] It should be noted that the time for depressurization or agitation-induced depressurization is preferably at a level that promotes the removal of solvents contained in the spray without reducing production efficiency.

[0073] The manufacturing method of the present invention can perform heating in the above-mentioned spraying / mixing process. Preferably, the maximum temperature of the sprayed material is 40°C to 150°C, more preferably 50°C to 140°C, and particularly preferably 60°C to 130°C. If the maximum temperature of the sprayed material is lower than the above-mentioned lower limit, the content of the aerosol (or other aerosol agent?) in the sprayed material increases due to the spraying of the aerosol, and the fluidity of the sprayed material is significantly reduced. This may result in uneven distribution of the compounds in the sprayed material, leading to a decrease in quality, or the aerosol adhering to the mixer. Furthermore, during the firing process, more heat needs to be applied to promote the volatilization of the aerosol, making it difficult to properly control the firing and potentially reducing production efficiency. Conversely, if the temperature of the sprayed material is higher than the above-mentioned upper limit, the amount of tertiary agglomerated particles may increase excessively.

[0074] There are no particular limitations on the method of heating described above. In order to make the maximum temperature of the sprayed material reach the temperature range described above, the following methods can be used, for example: surrounding the outer edge of the container holding the sprayed material, such as a sprayer / mixer, with a jacket or similar device, and circulating hot water at about 90°C; circulating oil heated to about 120°C; or circulating steam with a temperature adjusted to about 120°C to 160°C.

[0075] In the manufacturing method of the present invention, the spraying / mixing step of preparing a mixture by mixing the precursor compound with the lithium compound is a very simple operation. Preferably, a drying step of drying the sprayed material is performed after the spraying / mixing step, based on the average secondary particle size of the precursor compound related to the average secondary particle size of the target positive electrode active material.

[0076] For example, when the target is a positive electrode active material with a relatively large particle size of approximately 12 μm to approximately 30 μm for the precursor compound, as described above, by spraying the aerosol simultaneously with the preparation of the mixture, a mixture that maintains good flowability can be obtained even without drying. Furthermore, considering the volatilization of the aerosol contained during calcination, a drying step for drying the sprayed material can be performed after the spraying / mixing step. By calcining it, particles of the desired positive electrode active material can be obtained.

[0077] On the other hand, for example, when targeting a positive electrode active material having a relatively small average secondary particle size of about 1 μm to about 12 μm, particularly 2 μm to 7 μm, the increased content of the aerosol in the sprayed material due to spraying may lead to a significant decrease in the flowability of the sprayed material. Therefore, the drying of the sprayed material can be performed simultaneously with spraying the aerosol and preparing the mixture. As a result, the solvent contained in the aerosol present in the sprayed material can be appropriately removed in a shorter time, thereby enabling the sprayed material particles to have good flowability without reducing production efficiency.

[0078] In addition, the drying process is particularly important when the precursor compound has a large BET specific surface area. For example, when the target is a positive electrode active material with a small average secondary particle size of about 1 μm to about 6 μm, the precursor compound is a hydroxide or oxide with a BET specific surface area of ​​about 5 m². 2 / g~approximately 80m 2 In the case of / g, productivity can be increased, for example by drying at a higher temperature and controlling the process as described below.

[0079] In the aforementioned drying process, similar to the spraying / mixing process, the drying process can be carried out under reduced pressure conditions, i.e., pressure reduction, inside the container holding the sprayed material. Therefore, by performing the drying process under reduced pressure inside a container such as a sprayer / mixer, the solvent contained in the spray can be more easily removed to a level that does not impair the flowability of the sprayed material, depending on the particle size of the target positive electrode active material, thereby further improving productivity.

[0080] Furthermore, in the manufacturing method of the present invention, by performing the above-mentioned drying process under stirring and reduced pressure, the removal of the solvent contained in the spray can be further promoted.

[0081] When applying reduced pressure or agitated reduced pressure as described above, the vacuum level (gauge pressure) inside the container holding the aerosol is preferably -95 kPa or higher and less than 0 kPa, more preferably -95 kPa to -20 kPa, and particularly preferably -95 kPa to -30 kPa. If the vacuum level inside the container holding the aerosol is less than the lower limit mentioned above, the sprayed droplets may be drawn into the pressure reducing pump. By ensuring that the vacuum level inside the container holding the aerosol is less than 0 kPa, and further below the upper limit mentioned above, the effects of reduced pressure or agitated reduced pressure can be achieved, and the drying time can be shortened more easily, thereby further improving productivity.

[0082] It should be noted that the time for depressurization or agitation-induced depressurization is preferably at a level that promotes the removal of solvents contained in the spray without reducing production efficiency.

[0083] In the drying process described above, heating can be performed in the same manner as in the spraying / mixing process. Preferably, this heating is performed to ensure that the maximum temperature of the sprayed material reaches 40°C to 150°C, more preferably 50°C to 140°C, and particularly preferably 60°C to 130°C. If the maximum temperature of the sprayed material is lower than the lower limit mentioned above, the drying rate of the spray agent will be too slow, potentially leading to reduced production efficiency. Conversely, if the temperature of the sprayed material is higher than the upper limit mentioned above, the precursor compounds in the sprayed material may undergo uneven dehydration reactions, resulting in heterogeneous phases.

[0084] There are no particular limitations on the heating method used in the above drying process; the same method used in the above spray / mixing process can be employed.

[0085] Furthermore, the drying process is preferably approximately equal to the time required to obtain the mixture of the precursor compound and the lithium compound without the spraying process, and more preferably shorter than the time required to obtain the mixture. If the drying time to remove the solvent contained in the spray is too long, not only will the mixture begin to separate and its uniformity decrease, but production efficiency may also decrease.

[0086] It should be noted that, in the manufacturing method of the present invention, preferably, the heating of the sprayed material is performed in at least one of the above-described spraying / mixing process and the above-described drying process.

[0087] As described above, the main feature of the manufacturing method of the present invention is that, before the main calcination, a spraying / mixing process of a spraying agent is performed while preparing a mixture by mixing the precursor compound and the lithium compound. However, the target positive electrode active material can also be obtained by calcination at a specified temperature thereafter.

[0088] For example, during firing, the target positive electrode active material can be obtained by firing twice or more, changing the temperature from low to high. In this case, if the previous low-temperature firing is the pre-firing (hereinafter referred to as pre-firing) and the subsequent high-temperature firing is the main firing, the pre-firing can be carried out in the spray / mixing process described above, or in the drying process as required after the spray / mixing process, or it can be carried out after the drying process.

[0089] This pre-firing process enhances the reactivity of the precursor compound with the lithium compound, allowing the lithium compound to decompose and melt relative to the precursor compound, resulting in a more reliable and uniform synthesis reaction. Consequently, crystal growth and particle growth can be promoted during the subsequent main firing, making it easier to obtain the desired particle shape and composition of the positive electrode active material.

[0090] The firing temperature for the pre-firing is not particularly limited, but is preferably less than 750°C, more preferably 350°C to 750°C, and particularly preferably 350°C to 700°C. If the firing temperature for pre-firing is too low, the reactivity between the precursor compound and the lithium compound may not be sufficiently improved. Conversely, if the firing temperature for pre-firing is higher than the above-mentioned upper limit, excessive crystal growth may occur during the main firing, and the battery characteristics of the resulting positive electrode active material may be reduced. In addition, the time for maintaining the high temperature during pre-firing is not particularly limited as long as it is sufficient to improve the reactivity between the precursor compound and the lithium compound, but is generally preferably about 1 hour to about 10 hours.

[0091] The main calcination following the above-mentioned spray / mixing process, or the drying process selected as needed, can be carried out, for example, in an oxidizing atmosphere. This oxidizing atmosphere can be obtained by setting the oxygen concentration according to the valence state of the positive electrode active material after the main calcination of the precursor compound, for example, preferably an oxygen concentration of about 18 vol% to about 99 vol%.

[0092] The firing temperature, which is the highest temperature for the main firing, is not particularly limited and can be adjusted appropriately according to the composition of the target positive electrode active material. Furthermore, the main firing temperature can be higher than the pre-firing temperature, for example, preferably 650°C to 1100°C, more preferably 700°C to 1000°C. If the main firing temperature is lower than the lower limit mentioned above, it may be impossible to obtain a positive electrode active material with the desired crystalline structure and particle state. Conversely, if the main firing temperature is higher than the upper limit mentioned above, excessive crystal growth may occur, and the battery characteristics of the resulting positive electrode active material may be reduced. In addition, if the valence balance of the desired positive electrode active material is poor, the battery characteristics may be reduced when a non-aqueous electrolyte secondary battery is manufactured. Furthermore, the firing time after reaching the highest temperature for the main firing is not particularly limited, as long as a positive electrode active material with the desired crystalline structure is obtained; it is generally preferred to be about 1 hour to about 10 hours.

[0093] It should be noted that in the manufacturing method of the present invention, during the pre-firing process as described above, the main firing process promotes crystal growth and particle growth, and the firing efficiency also increases. As a result, from the viewpoints of composition, particle size, and crystallinity, a positive electrode active material with higher uniformity and the desired crystalline structure can be obtained.

[0094] The volume-based average secondary particle size of the positive electrode active material is preferably, for example, 1 μm to 20 μm. If this average secondary particle size is less than the lower limit mentioned above, the reactivity of the positive electrode active material with the electrolyte will be high when used as the positive electrode, and the battery characteristics may be reduced. Conversely, if this average secondary particle size is greater than the upper limit mentioned above, the contact between the positive electrode active material and the electrolyte will deteriorate when used as the positive electrode, making it impossible to maintain the necessary output, which may lead to a reduction in battery characteristics.

[0095] Therefore, by using the positive electrode active material obtained by the manufacturing method of the present invention as the positive electrode, the desired non-aqueous electrolyte secondary battery can be manufactured.

[0096] The aforementioned non-aqueous electrolyte secondary batteries typically consist of a positive electrode, a negative electrode, and an electrolyte solution containing electrolyte.

[0097] In manufacturing the aforementioned positive electrode, a conductive agent and a binder are added and mixed into the positive electrode active material obtained by the manufacturing method of the present invention, according to conventional methods. As a conductive agent, acetylene black, carbon black, lead black, etc., are preferred, for example. As a binder, polytetrafluoroethylene, polyvinylidene fluoride, etc., are preferred, for example.

[0098] The aforementioned negative electrode may use at least one non-metallic or metallic element selected from Si, Al, Sn, Pb, Zn, Bi, and Cd; alloys containing such elements or chalcogenides containing such elements; and negative electrode active materials such as lithium metal, graphite, and low-crystallinity carbon materials.

[0099] In addition to the combination of ethylene carbonate and diethyl carbonate, organic solvents containing at least one of carbonates such as propylene carbonate and dimethyl carbonate, and esters such as dimethyl carbonate, can also be used as solvents for the electrolyte.

[0100] In addition to lithium hexafluoride phosphate, at least one of lithium salts such as lithium perchlorate and lithium tetrafluoride borate can be dissolved in the above solvent as the electrolyte.

[0101] <Function>

[0102] In the manufacturing method described in this invention, the mixing of the precursor compound and the lithium compound is carried out simultaneously with the spraying of an aerosol containing at least one element. Therefore, the manufacturing method described in this invention not only avoids adversely affecting the battery characteristics of non-aqueous electrolyte secondary batteries, but also allows for the easy manufacture of positive electrode active materials that improve the battery characteristics of non-aqueous electrolyte secondary batteries without reducing production efficiency.

[0103] [Example]

[0104] The present invention will be specifically described below with reference to representative embodiments and comparative examples, but the present invention is not limited to these embodiments.

[0105] Composition of precursor compounds and positive electrode active materials

[0106] In this specification, the composition of the precursor compound and the positive electrode active material is determined using the following method.

[0107] 0.2 g of the precursor compound or positive electrode active material was dissolved in 25 mL of 20% hydrochloric acid solution by heating. After cooling, the solution was transferred to a 100 mL volumetric flask, and pure water was added to prepare an adjustment solution. The elements in the adjustment solution were quantified using ICP-AES (Optima 8300, manufactured by PerkinElmer Japan Co., Ltd.).

[0108] <XRD Diffraction of Positive Electrode Active Materials>

[0109] XRD diffraction data were obtained using an X-ray diffraction apparatus (SmartLab, Rigaku Corporation) under the following X-ray diffraction conditions. The obtained XRD diffraction data were then used to confirm the presence or absence of anomalies.

[0110] (X-ray diffraction conditions)

[0111] X-ray source: Cu-Kα

[0112] Accelerating voltage and current: 45kV and 200mA

[0113] Sampling width: 0.02deg.

[0114] Scan width: 15deg~122deg.

[0115] Scanning speed: 0.4° / min

[0116] Diverging slit width: 0.65 deg.

[0117] Light-receiving slit width: 0.2mm

[0118] Scattering slit: 0.65 deg.

[0119] <Preparation of Precursor Compound A>

[0120] Aqueous solutions of nickel sulfate, cobalt sulfate, and manganese sulfate were mixed to achieve a molar ratio of Ni:Co:Mn of 1:1:1, resulting in a mixed aqueous solution. In the reaction vessel, 10 L of pure water containing 300 g of sodium hydroxide solution and 500 g of ammonia was prepared beforehand as a mother liquor. N2 gas was passed through the reaction vessel at a flow rate of 0.7 L / min to create an N2 atmosphere. It should be noted that the reaction itself was also conducted under an N2 atmosphere.

[0121] Then, the stirring blades are rotated at 1000 rpm and the above mixed aqueous solution, sodium hydroxide aqueous solution and ammonia are added dropwise at a specified speed. The amount of alkaline solution added is adjusted so that the pH value reaches 12.0 to carry out the crystallization reaction. Through the crystallization reaction, co-precipitation is carried out so that Ni, Co and Mn crystallize to form aggregated particles, and a coprecipitate is obtained.

[0122] Then, the slurry in the reactor was separated into solid and liquid components, and then washed with pure water to reduce residual impurities. The co-precipitate in a clumped state was dried at 110°C for 12 hours in an atmospheric environment to obtain precursor compound A with an average secondary particle size of 4.9 μm.

[0123] <Preparation of Precursor Compound B>

[0124] Aqueous solutions of nickel sulfate, cobalt sulfate, and manganese sulfate were mixed to achieve a molar ratio of Ni:Co:Mn of 1:1:1, resulting in a mixed aqueous solution. In the reaction vessel, 10 L of pure water containing 360 g of sodium hydroxide aqueous solution and 500 g of ammonia was prepared beforehand as a mother liquor. N2 gas was passed through the reaction vessel at a flow rate of 0.7 L / min to create an N2 atmosphere. It should be noted that the reaction itself was also conducted under an N2 atmosphere.

[0125] Then, the stirring blades are rotated at 1000 rpm and the above mixed aqueous solution, sodium hydroxide aqueous solution and ammonia are added dropwise at a specified speed. The amount of alkaline solution added is adjusted so that the pH value reaches 12.5 to carry out the crystallization reaction. Through the crystallization reaction, co-precipitation is carried out so that Ni, Co and Mn crystallize to form aggregated particles and obtain coprecipitate.

[0126] Then, the slurry in the reactor was separated into solid and liquid components, and then washed with pure water to reduce residual impurities. The co-precipitate in a clumped state was dried at 110°C for 12 hours in an atmospheric environment to obtain precursor compound B with an average secondary particle size of 3.0 μm.

[0127] [Setting the drying endpoint A]

[0128] The precursor compound A and lithium carbonate were weighed such that the molar ratio of Li to the total amount of Ni, Co, and Mn was Li / (Ni+Co+Mn) = 1.05. They were then mixed in a spray / mixer to obtain a mixture of precursor compound A and lithium carbonate. The moisture content of the mixture was then measured to be 0.48 wt%. Based on this moisture content, the drying endpoint A in the drying process of Examples 1-14 and Comparative Examples 1-2 was set to 0.50 wt% or less.

[0129] [Setting the drying endpoint B]

[0130] The precursor compound B and lithium carbonate were weighed such that the molar ratio of Li to the total amount of Ni, Co, and Mn was Li / (Ni+Co+Mn) = 1.05. The precursor compound B and lithium carbonate were then mixed in a spray / mixer to obtain a mixture of precursor compound B and lithium carbonate. Subsequently, the moisture content of the mixture was measured to be 0.96 wt%. Based on this moisture content, the drying endpoint B in the drying process of Example 15 was set to be 1.00 wt% or less.

[0131] It should be noted that the moisture content of the mixture or sprayed material in this specification was determined using a halogen moisture meter (model: MB120, manufactured by OHAUS Corporation), and the weight loss when heated to 120°C was taken as the moisture content.

[0132] <Example 1>

[0133] according to Figure 1 The flowchart shown (process α) describes the production of the positive electrode active material.

[0134] [Preparation process of the spray]

[0135] 43.6 g of powdered lithium hydroxide monohydrate (LiOH·H2O) was dissolved in 660.9 g of pure water to prepare an aqueous lithium hydroxide solution. Subsequently, 60.9 g of powdered tungsten oxide (WO3) was added to the above aqueous lithium hydroxide solution and stirred until the tungsten oxide was completely dissolved, to prepare 765.4 g of an aqueous Li4WO5 solution with a weight concentration (amount of elemental compound in the spray) of 10 wt%.

[0136] [Spraying / mixing process]

[0137] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed such that the molar ratio of Li to Ni, Co, and Mn was Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, while mixing them in the spray / mixer, 383 g of the above-mentioned Li₄WO₅ aqueous solution was sprayed onto the mixed powder for 10 minutes.

[0138] [Drying Process]

[0139] Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa, and the material to be sprayed was heated while simultaneously being mixed. Once the temperature of the material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the material was then measured to be 0.47 wt%, indicating that drying was complete. The drying process took 8 minutes. The total processing time for both the spray / mixing and drying processes was 18 minutes. Heating of the material was achieved by circulating 95°C hot water through the spray / mixer.

[0140] [Firing process]

[0141] Subsequently, the sprayed material inside the sprayer / mixer was randomly collected at five points, and then calcined in an atmospheric environment at a maximum temperature of 950°C for 5 hours to obtain positive electrode active materials A1 to A5.

[0142] [Evaluation of the uniformity of sprayed compounds]

[0143] For the obtained positive electrode active materials A1 to A5, the molar ratio of W to (Ni+Co+Mn) [W / (Ni+Co+Mn)] was determined using the following method. This molar ratio was multiplied by 100 to obtain the value used as the spray compound / Me (mol%) 1 to 5 for evaluation. Furthermore, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5. It should be noted that in Example 1, Examples 2 to 11, 13, and 15 described later, and Comparative Examples 1 to 3, the spray compound was W, and Me = (Ni+Co+Mn).

[0144] Determination of the molar ratio (W / (Ni+Co+Mn))

[0145] A 0.2 g sample of the positive electrode active material was dissolved by heating in 25 mL of 20% hydrochloric acid solution. After cooling, the solution was transferred to a 100 mL volumetric flask, and purified water was added to prepare an adjustment solution. The elements in this adjustment solution were quantified using ICP-AES (Optima 8300, manufactured by PerkinElmer Japan Co., Ltd.).

[0146] <Example 2>

[0147] according to Figure 2 The flowchart shown (process β) illustrates the production of the positive electrode active material.

[0148] [Preparation process of the spray]

[0149] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0150] [Spraying / mixing process]

[0151] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed such that the molar ratio of Li to Ni, Co, and Mn was Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, while mixing them in the spray / mixer, the powder mixture was simultaneously heated, and 383 g of the aforementioned Li₄WO₅ aqueous solution was sprayed onto the powder mixture for 10 minutes. The heating of the powder mixture was adjusted by circulating 95°C hot water in the spray / mixer.

[0152] [Drying Process]

[0153] Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa, and the material to be sprayed was kept heated to begin mixing. When the temperature of the material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the material was then measured to be 0.45 wt%, indicating that drying was complete. The drying process took 6 minutes. The total processing time for the spray / mixing and drying processes was 16 minutes.

[0154] [Firing process]

[0155] Subsequently, the sprayed material inside the sprayer / mixer was randomly collected at five points, and then calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials B1 to B5.

[0156] [Evaluation of the uniformity of sprayed compounds]

[0157] For the obtained positive electrode active materials B1 to B5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0158] <Example 3>

[0159] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0160] [Preparation process of the spray]

[0161] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0162] [Spraying / mixing process]

[0163] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed to achieve a molar ratio of Li to Ni, Co, and Mn of Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa. While mixing the precursor compound and lithium carbonate in the spray / mixer, the powder mixture was simultaneously heated, and 383 g of the aforementioned Li₄WO₅ aqueous solution was sprayed onto the powder mixture for 10 minutes. The heating of the powder mixture was achieved by circulating 95°C hot water in the spray / mixer.

[0164] [Drying Process]

[0165] Subsequently, the vacuum level inside the spray / mixer was maintained at -70 kPa, and the material being sprayed was heated to begin mixing. When the temperature of the material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.46 wt%, indicating that drying was complete. The drying process took 4 minutes. The total processing time for the spray / mixing and drying processes was 14 minutes.

[0166] [Firing process]

[0167] Subsequently, the sprayed material inside the spray / mixer was randomly collected at five points, and then calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials C1 to C5.

[0168] [Evaluation of the uniformity of sprayed compounds]

[0169] For the obtained positive electrode active materials C1 to C5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1. The value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0170] <Example 4>

[0171] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0172] [Preparation process of the spray]

[0173] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0174] [Spraying / mixing process]

[0175] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed to achieve a molar ratio (Li / (Ni+Co+Mn)) of Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa. While mixing the compounds in the spray / mixer, the powder mixture was simultaneously heated, and 383 g of the aforementioned Li₄WO₅ aqueous solution was sprayed onto the powder mixture for 10 minutes. The heating of the powder mixture was adjusted by circulating 120°C steam in the spray / mixer.

[0176] [Drying Process]

[0177] Subsequently, the vacuum level inside the spray / mixer was maintained at -70 kPa, and the material being sprayed was heated to begin mixing. When the temperature of the material reached 115°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the material was then measured to be 0.45 wt%, indicating that drying was complete. The drying process took 4 minutes. The total processing time for the spray / mixing and drying processes was 14 minutes.

[0178] [Firing process]

[0179] Subsequently, the sprayed material inside the spray / mixer was randomly collected at five points, and each material was calcined in an atmospheric atmosphere at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials D1 to D5.

[0180] [Evaluation of the uniformity of sprayed compounds]

[0181] For the obtained positive electrode active materials D1 to D5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0182] <Example 5>

[0183] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0184] [Preparation process of the spray]

[0185] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0186] [Spraying / mixing process]

[0187] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed to achieve a molar ratio (Li / (Ni+Co+Mn)) of Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa. While mixing the compounds in the spray / mixer, the powder mixture was simultaneously heated, and 383 g of the aforementioned Li₄WO₅ aqueous solution was sprayed onto the powder mixture for 10 minutes. The heating of the powder mixture was achieved by circulating 83°C hot water in the spray / mixer.

[0188] [Drying Process]

[0189] Subsequently, the vacuum level inside the spray / mixer was maintained at -70 kPa, and the heating of the sprayed material was continued to initiate the mixing process. After the temperature of the sprayed material reached 80°C, the temperature was maintained at 80°C for 2 minutes. Then, the pressure inside the spray / mixer was adjusted to atmospheric pressure to complete the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.47 wt%, thus indicating that drying was complete. The drying process took 6 minutes. The total processing time for the spray / mixing and drying processes was 16 minutes.

[0190] [Firing process]

[0191] Subsequently, the sprayed material inside the sprayer / mixer was randomly collected at five points, and then calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials E1 to E5.

[0192] [Evaluation of the uniformity of sprayed compounds]

[0193] For the obtained positive electrode active materials E1 to E5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0194] <Example 6>

[0195] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0196] [Preparation process of the spray]

[0197] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0198] [Spraying / mixing process]

[0199] Precursor compound A and lithium carbonate (Li₂CO₃) were weighed to achieve a molar ratio of Li to Ni, Co, and Mn of Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa. While mixing the powder in the spray / mixer, the powder was simultaneously heated, and 383 g of the aforementioned Li₄WO₅ aqueous solution was sprayed onto the powder for 10 minutes. The heating of the powder was achieved by circulating 73°C hot water in the spray / mixer.

[0200] [Drying Process]

[0201] Subsequently, the vacuum level inside the spray / mixer was maintained at -70 kPa, and the heating of the sprayed material was continued to initiate the mixing process. After the temperature of the sprayed material reached 70°C, it was maintained at 70°C for 4 minutes. Then, the pressure inside the spray / mixer was adjusted to atmospheric pressure to complete the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.47 wt%, thus indicating that drying was complete. The drying process took 8 minutes. The total processing time for the spray / mixing and drying processes was 18 minutes.

[0202] [Firing process]

[0203] Subsequently, the sprayed material inside the sprayer / mixer was randomly collected at five points, and each material was calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials F1 to F5.

[0204] [Evaluation of the uniformity of sprayed compounds]

[0205] For the obtained positive electrode active materials F1 to F5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0206] <Example 7>

[0207] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0208] [Preparation process of the spray]

[0209] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0210] [Spraying / mixing process]

[0211] Precursor compound A and lithium carbonate (Li₂CO₃) were weighed to achieve a molar ratio of Li to Ni, Co, and Mn of Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa. While mixing the powder in the spray / mixer, the powder was simultaneously heated, and 383 g of the aforementioned Li₄WO₅ aqueous solution was sprayed onto the powder for 10 minutes. The heating of the powder was achieved by circulating 62°C hot water in the spray / mixer.

[0212] [Drying Process]

[0213] Subsequently, the vacuum level inside the spray / mixer was maintained at -70 kPa, and the heating of the sprayed material was continued to initiate the mixing process. After the temperature of the sprayed material reached 60°C, the temperature was maintained at 60°C for 7 minutes. Then, the pressure inside the spray / mixer was adjusted to atmospheric pressure to complete the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.48 wt%, thus indicating that drying was complete. The drying process took 13 minutes. The total processing time for the spray / mixing and drying processes was 23 minutes.

[0214] [Firing process]

[0215] Subsequently, the sprayed material inside the spray / mixer was randomly collected at five points, and each material was calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials G1 to G5.

[0216] [Evaluation of the uniformity of sprayed compounds]

[0217] For the obtained positive electrode active materials G1 to G5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0218] <Example 8>

[0219] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0220] [Preparation process of the spray]

[0221] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0222] [Spraying / mixing process]

[0223] Precursor compound A and lithium carbonate (Li₂CO₃) were weighed to achieve a molar ratio of Li to Ni, Co, and Mn of Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, the vacuum level inside the spray / mixer was adjusted to -90 kPa. While mixing the powder in the spray / mixer, the powder was simultaneously heated, and 383 g of the aforementioned Li₄WO₅ aqueous solution was sprayed onto the powder for 10 minutes. The heating of the powder was achieved by circulating 95°C hot water in the spray / mixer.

[0224] [Drying Process]

[0225] Subsequently, the vacuum level inside the spray / mixer was maintained at -90 kPa, and the material being sprayed was heated to begin mixing. Once the temperature of the material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.46 wt%, indicating that drying was complete. The drying process took 3 minutes. The total processing time for both the spray / mixing and drying processes was 13 minutes.

[0226] [Firing process]

[0227] Subsequently, the sprayed material inside the spray / mixer was randomly collected at five points, and each material was calcined in an atmospheric atmosphere at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials H1 to H5.

[0228] [Evaluation of the uniformity of sprayed compounds]

[0229] For the obtained positive electrode active materials H1 to H5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1. The value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0230] <Example 9>

[0231] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0232] [Preparation process of the spray]

[0233] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0234] [Spraying / mixing process]

[0235] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed to achieve a molar ratio of Li to Ni, Co, and Mn of Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, the vacuum level inside the spray / mixer was adjusted to -40 kPa. While mixing the compounds in the spray / mixer, the powder mixture was simultaneously heated, and 383 g of the aforementioned Li₄WO₅ aqueous solution was sprayed onto the powder mixture for 10 minutes. The heating of the powder mixture was achieved by circulating 95°C hot water in the spray / mixer.

[0236] [Drying Process]

[0237] Subsequently, the vacuum level inside the spray / mixer was maintained at -40 kPa, and the material being sprayed was heated to begin mixing. When the temperature of the material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.45 wt%, indicating that drying was complete. The drying process took 6 minutes. The total processing time for the spray / mixing and drying processes was 16 minutes.

[0238] [Firing process]

[0239] Subsequently, the sprayed material inside the spray / mixer was randomly collected at five points, and then calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials I1 to I5.

[0240] [Evaluation of the uniformity of sprayed compounds]

[0241] For the obtained positive electrode active materials I1 to I5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0242] <Example 10>

[0243] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0244] [Preparation process of the spray]

[0245] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0246] [Spraying / mixing process]

[0247] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed such that the molar ratio of Li to Ni, Co, and Mn was Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, while mixing them in the spray / mixer, the powder mixture was simultaneously heated, and 383 g of the aforementioned Li₄WO₅ aqueous solution was sprayed onto the powder mixture for 10 minutes. The heating of the powder mixture was adjusted by circulating 95°C hot water in the spray / mixer.

[0248] [Drying Process]

[0249] Subsequently, the mixture process begins while the sprayed material remains heated. The heating and mixing process is completed when the temperature of the sprayed material reaches 90°C. The moisture content of the sprayed material is then measured to be 0.47 wt%, indicating that drying is complete. The drying process takes 11 minutes. The total processing time for the spraying / mixing and drying processes is 21 minutes.

[0250] [Firing process]

[0251] Subsequently, the sprayed material inside the spray / mixer was randomly collected at five points, and then calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials J1 to J5.

[0252] [Evaluation of the uniformity of sprayed compounds]

[0253] For the obtained positive electrode active materials J1 to J5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0254] <Example 11>

[0255] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0256] [Preparation process of the spray]

[0257] 21.8 g of powdered lithium hydroxide monohydrate (LiOH·H2O) was dissolved in 604.3 g of pure water to prepare a lithium hydroxide aqueous solution. Subsequently, 60.9 g of powdered tungsten oxide (WO3) was added to the above lithium hydroxide aqueous solution and stirred until the tungsten oxide was completely dissolved, preparing 687 g of a Li2WO4 aqueous solution with a weight concentration (amount of elemental compound in the spray) of 10 wt%.

[0258] [Spraying / mixing process]

[0259] Precursor compound A and lithium carbonate (Li₂CO₃) were weighed to achieve a molar ratio of Li to Ni, Co, and Mn of Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa. While mixing the powder in the spray / mixer, the powder was simultaneously heated, and 383 g of the aforementioned Li₂WO₄ aqueous solution was sprayed onto the powder for 10 minutes. The heating of the powder was achieved by circulating 95°C hot water in the spray / mixer.

[0260] [Drying Process]

[0261] Subsequently, the vacuum level inside the spray / mixer was maintained at -70 kPa, and the material being sprayed was heated to begin mixing. When the temperature of the material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.49 wt%, indicating that drying was complete. The drying process took 5 minutes. The total processing time for both the spray / mixing and drying processes was 15 minutes.

[0262] [Firing process]

[0263] Subsequently, the sprayed material inside the sprayer / mixer was randomly collected at five points, and each material was calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials K1 to K5.

[0264] [Evaluation of the uniformity of sprayed compounds]

[0265] For the obtained positive electrode active materials K1 to K5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0266] <Example 12>

[0267] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0268] [Preparation process of the spray]

[0269] 82g of powdered zirconium oxide (ZrO2) with an average secondary particle size of 114nm was added to 943g of pure water and stirred with a mixer to prepare 1025g of ZrO2 suspension with a weight concentration (amount of elemental compounds in the spray) of 8wt%.

[0270] [Spraying / mixing process]

[0271] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed to achieve a molar ratio of Li to Ni, Co, and Mn of Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa. While mixing the precursor compound and lithium carbonate in the spray / mixer, the powder mixture was simultaneously heated, and 205.3 g of the ZrO₂ suspension was sprayed onto the powder mixture for 10 minutes. The heating of the powder mixture was achieved by circulating 95°C hot water in the spray / mixer.

[0272] [Drying Process]

[0273] Subsequently, the vacuum level inside the spray / mixer was maintained at -70 kPa, and the material being sprayed was heated to begin mixing. When the temperature of the material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.49 wt%, indicating that drying was complete. The drying process took 5 minutes. The total processing time for both the spray / mixing and drying processes was 15 minutes.

[0274] [Firing process]

[0275] Subsequently, the sprayed material inside the sprayer / mixer was randomly collected at five points, and each material was calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials L1 to L5.

[0276] [Evaluation of the uniformity of sprayed compounds]

[0277] For the obtained positive electrode active materials L1 to L5, the [Zr / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. Furthermore, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5. It should be noted that in Example 12 and Example 14 described later, the spray compound was Zr, and Me = (Ni+Co+Mn).

[0278] <Example 13>

[0279] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0280] [Preparation process of the spray]

[0281] 43.6 g of powdered lithium hydroxide monohydrate (LiOH·H2O) was dissolved in 243.4 g of pure water to prepare an aqueous lithium hydroxide solution. Subsequently, 60.9 g of powdered tungsten oxide (WO3) was added to the above aqueous lithium hydroxide solution and stirred until the tungsten oxide was completely dissolved, to prepare 347.9 g of an aqueous Li4WO5 solution with a weight concentration (amount of elemental compound in the spray) of 22 wt%.

[0282] [Spraying / mixing process]

[0283] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed such that the molar ratio of Li to Ni, Co, and Mn was Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, while mixing them in the spray / mixer, 146.7 g of the above-mentioned Li₄WO₅ aqueous solution was sprayed onto the mixed powder for 10 minutes.

[0284] [Drying Process]

[0285] Subsequently, after adjusting the vacuum level inside the spray / mixer to -70 kPa, heating of the sprayed material and simultaneous mixing began. When the temperature of the sprayed material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.45 wt%, thus indicating that drying was complete. The drying process took 2 minutes. The total processing time for the spray / mixing and drying processes was 12 minutes. Heating of the sprayed material was achieved by circulating 95°C hot water through the spray / mixer.

[0286] [Firing process]

[0287] Subsequently, the sprayed material inside the spray / mixer was randomly collected at five points, and each material was calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials M1 to M5.

[0288] [Evaluation of the uniformity of sprayed compounds]

[0289] For the obtained positive electrode active materials M1 to M5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0290] <Example 14>

[0291] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0292] [Preparation process of the spray]

[0293] 82g of powdered zirconium oxide (ZrO2) with an average secondary particle size of 114nm was added to 159.2g of pure water and stirred with a mixer to prepare 241.2g of ZrO2 suspension with a weight concentration (amount of elemental compounds in the spray) of 34wt%.

[0294] [Spraying / mixing process]

[0295] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed to achieve a molar ratio (Li / (Ni+Co+Mn)) of Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa. While mixing the precursor compound and lithium carbonate in the spray / mixer, the powder mixture was simultaneously heated, and 48.3 g of the ZrO₂ suspension was sprayed onto the powder mixture for 10 minutes. The heating of the powder mixture was achieved by circulating 95°C hot water in the spray / mixer.

[0296] [Drying Process]

[0297] Subsequently, the vacuum level inside the spray / mixer was maintained at -70 kPa, and the heating of the sprayed material was continued to initiate the mixing process. When the temperature of the sprayed material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.48 wt%, thus indicating that drying was complete. The drying process took 1 minute. The total processing time for the spray / mixing and drying processes was 11 minutes.

[0298] [Firing process]

[0299] Subsequently, the sprayed material inside the sprayer / mixer was randomly collected at five points, and each material was calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials N1 to N5.

[0300] [Evaluation of the uniformity of sprayed compounds]

[0301] For the obtained positive electrode active materials N1 to N5, the [Zr / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of the spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0302] <Example 15>

[0303] according to Figure 3 The flowchart shown (process γ) illustrates the production of the positive electrode active material.

[0304] [Preparation process of the spray]

[0305] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0306] [Spraying / mixing process]

[0307] The precursor compound B and lithium carbonate (Li₂CO₃) were weighed such that the molar ratio of Li to Ni, Co, and Mn was Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound B and lithium carbonate was 3525 g. Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa, and while mixing the compounds in the spray / mixer, the powder being mixed was simultaneously heated. Then, 383 g of the aforementioned Li₄WO₅ aqueous solution was sprayed onto the powder for 10 minutes. The heating of the powder was achieved by circulating 95°C hot water in the spray / mixer.

[0308] [Drying Process]

[0309] Subsequently, the vacuum level inside the spray / mixer was maintained at -70 kPa, and the heating of the sprayed material was continued to initiate the mixing process. When the temperature of the sprayed material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.97 wt%, thus indicating that drying was complete. The drying process took 4 minutes. The total processing time for the spray / mixing and drying processes was 14 minutes.

[0310] [Firing process]

[0311] Subsequently, the sprayed material inside the sprayer / mixer was randomly collected at five points, and then calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials O1 to O5.

[0312] [Evaluation of the uniformity of sprayed compounds]

[0313] For the obtained positive electrode active materials O1 to O5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0314] <Comparative Example 1>

[0315] according to Figure 4 The flowchart shown (process δ) illustrates the production of the positive electrode active material.

[0316] [Preparation process of the spray]

[0317] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0318] [Mixed Process]

[0319] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed such that the molar ratio of Li to Ni, Co, and Mn was Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. The mixture was then mixed in the spray / mixer for 10 minutes to obtain a final mixture.

[0320] [Spraying process]

[0321] Subsequently, while stirring the above mixture, 383g of the above Li4WO5 aqueous solution was sprayed onto the mixture for 10 minutes.

[0322] [Drying Process]

[0323] Subsequently, the vacuum level inside the spray / mixer was adjusted to -70 kPa, and the material to be sprayed was heated while simultaneously being mixed. Once the temperature of the material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the material was then measured to be 0.46 wt%, indicating that drying was complete. The drying process took 7 minutes. The total processing time for the mixing, spraying, and drying processes was 27 minutes.

[0324] [Firing process]

[0325] Subsequently, the sprayed material inside the spray / mixer was randomly collected at five points, and each material was calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials P1 to P5.

[0326] [Evaluation of the uniformity of sprayed compounds]

[0327] For the obtained positive electrode active materials P1 to P5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0328] <Comparative Example 2>

[0329] according to Figure 5The flowchart shown (process ε) illustrates the fabrication of the positive electrode active material.

[0330] [Preparation process of the spray]

[0331] Similar to Example 1, 765.4 g of an aqueous solution of Li4WO5 with a weight concentration of 10 wt% was prepared.

[0332] [Mixed Process]

[0333] The precursor compound A and lithium carbonate (Li₂CO₃) were weighed such that the molar ratio of Li to Ni, Co, and Mn was Li / (Ni+Co+Mn) = 1.05, and then placed in a spray / mixer. The total weight of precursor compound A and lithium carbonate was 3525 g. The mixture was then mixed in the spray / mixer for 10 minutes to obtain a final mixture.

[0334] [Spraying process]

[0335] Subsequently, after adjusting the vacuum level inside the spray / mixer to -70 kPa, the mixture was heated, and while stirring, 383 g of the above-mentioned Li4WO5 aqueous solution was sprayed onto the mixture for 10 minutes. The heating of the mixture was adjusted by circulating 95°C hot water in the spray / mixer.

[0336] [Drying Process]

[0337] Subsequently, the vacuum level inside the spray / mixer was maintained at -70 kPa, and heating of the sprayed material was initiated while simultaneously initiating mixing. Once the temperature of the sprayed material reached 90°C, the pressure inside the spray / mixer was adjusted to atmospheric pressure, completing the heating and mixing process. The moisture content of the sprayed material was then measured to be 0.47 wt%, thus indicating that drying was complete. The drying process took 4 minutes. The total processing time for the mixing, spraying, and drying processes was 24 minutes.

[0338] [Firing process]

[0339] Subsequently, the sprayed material inside the spray / mixer was randomly collected at five points, and each material was calcined in an atmospheric environment at a maximum temperature of 950℃ for 5 hours to obtain positive electrode active materials Q1 to Q5.

[0340] [Evaluation of the uniformity of sprayed compounds]

[0341] For the obtained positive electrode active materials Q1 to Q5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5.

[0342] <Comparative Example 3>

[0343] according to Figure 6 The flowchart shown (process ζ) illustrates the production of the positive electrode active material.

[0344] [Preparation process of powder for mixing]

[0345] 25.1 g of powdered lithium hydroxide monohydrate (LiOH·H2O) and 60.9 g of powdered tungsten oxide (WO3) were mixed and calcined at 200 °C for 5 hours in a decarbonated atmospheric atmosphere to prepare Li4WO5 powder.

[0346] [Mixed Process]

[0347] The precursor compound A, lithium carbonate (Li₂CO₃), and Li₄WO₅ powder were weighed such that the molar ratio of Li to Ni, Co, and Mn was Li / (Ni+Co+Mn) = 1.05 and W / (Ni+Co+Mn) (molar ratio) was 0.005, and then placed in a spray / mixer. The total weight of precursor compound A, lithium carbonate, and Li₄WO₅ powder was 3584 g. The mixture was then mixed in the spray / mixer for 10 minutes to obtain a mixture. It should be noted that the moisture content of the mixture was determined to be 0.48 wt%.

[0348] [Firing process]

[0349] Subsequently, the mixture inside the spray / mixer was randomly collected at five points, and each mixture was calcined in an atmospheric atmosphere at a maximum temperature of 950°C for 5 hours to obtain positive electrode active materials R1 to R5.

[0350] [Evaluation of the uniformity of sprayed compounds]

[0351] For the obtained positive electrode active materials R1 to R5, the [W / (Ni+Co+Mn)] (molar ratio) was measured in the same manner as in Example 1, and the value obtained by multiplying this molar ratio by 100 was used as the spray compound / Me (mol%) 1 to 5 for evaluation. In addition, the standard deviation of spray compound / Me (mol%) was calculated using these spray compounds / Me (mol%) 1 to 5. It should be noted that in this Comparative Example 3, for convenience, "uniformity of mixed compounds" and "mixed compound / Me (mol%)" are expressed as "uniformity of spray compounds" and "spray compound / Me (mol%)".

[0352] The manufacturing conditions of the positive electrode active material in Examples 1-15 and Comparative Examples 1-3, the average secondary particle size (μm) of the precursor compound, the moisture content (wt%) of the sprayed material (Examples 1-15 and Comparative Examples 1-2) or the mixture (Comparative Example 3), the sprayed compound / Me (mol%) 1-5, the standard deviation of the sprayed compound / Me (mol%), and the uniformity evaluation results of the sprayed compound are shown together in Tables 1 and 2 below.

[0353] It should be noted that the evaluation criteria for the uniformity of the sprayed compound are as follows.

[0354] ○: Standard deviation is less than 0.02 (mol%).

[0355] ×: The standard deviation is above 0.02 (mol%).

[0356] In addition, the presence or absence of different phases in the positive electrode active materials obtained in Examples 1-15 and Comparative Examples 1-3 was confirmed according to the above method, and no different phases were found in any of the positive electrode active materials.

[0357]

[0358]

[0359] As shown in Tables 1 and 2, compared with Comparative Examples 1 to 2 which use processes δ or ε that separate the mixing and spraying processes based on conventional manufacturing methods, Examples 1 to 15 which use processes α, β, or γ that perform spraying / mixing processes based on the manufacturing method of the present invention have shorter total processing time and can manufacture positive electrode active materials with better production efficiency.

[0360] Compared to Example 1, which uses process α in the spray / mixing step without heating, Example 2, which uses process β in the spray / mixing step with heating, has a shorter total processing time and can manufacture the positive electrode active material with better production efficiency. Furthermore, compared to Example 2, Examples 3-4, which use process γ in the spray / mixing and drying steps under reduced pressure, can further manufacture the positive electrode active material with even better production efficiency.

[0361] In Examples 3, 8, and 9, where the vacuum level inside the spray / mixer where the sprayed material is stored in process γ is set to less than 0 kPa, the drying time is shorter compared to Example 10, where the vacuum level inside the spray / mixer is set to 0 kPa. This results in a shorter total processing time, enabling the production of positive electrode active materials with even better efficiency. Furthermore, processing can be performed with shorter drying times by following the order of vacuum levels from high to low in Examples 8, 3, and 9.

[0362] In Example 12, which uses a suspension of ZrO2 as a spray agent and employs process γ, the production efficiency is also as excellent as that of Examples 3 and 11, which use an aqueous solution of Li4WO5 or an aqueous solution of Li2WO4 as a spray agent and employ process γ.

[0363] In Example 13, where the amount of elemental compound in the spray is 22 wt%, and in Example 14, where the amount of elemental compound in the spray is 34 wt%, it was also confirmed that the spray compound had the same excellent uniformity as in Examples 3 and 12, and the total processing time was shorter than in Example 1, enabling the further production of positive electrode active materials with good production efficiency.

[0364] In Example 15, where the average secondary particle size of the precursor compound was 3.0 μm, it was confirmed that the uniformity of the sprayed compound was as good as that in Example 3, where the average secondary particle size of the precursor compound was 4.9 μm. Furthermore, the total processing time was shorter than that in Example 1, enabling the further production of a high-efficiency positive electrode active material.

[0365] Furthermore, as shown in Tables 1 and 2, in Comparative Example 3, which uses a process ζ based on a conventional manufacturing method to mix a precursor compound and a lithium compound with a W compound, the standard deviation of the spray compound / Me (mol%) is very large, and the uniformity of the spray compound is poor. However, in Examples 1 to 15, which use processes α, β, or γ based on the manufacturing method of the present invention to perform a spraying / mixing process of spraying a mixture of a precursor compound and a lithium compound with a spray containing a W compound and a Zr compound, the standard deviation of the spray compound / Me (mol%) is small, and the uniformity of the spray compound is excellent.

[0366] -Industry availability-

[0367] The positive electrode active material manufactured by the manufacturing method of the present invention not only does not adversely affect the battery characteristics of non-aqueous electrolyte secondary batteries, but can also improve the battery characteristics, and is therefore suitable as a positive electrode active material for non-aqueous electrolyte secondary batteries.

Claims

1. A method for manufacturing a positive electrode active material for a non-aqueous electrolyte secondary battery, characterized in that, The method for manufacturing the positive electrode active material for the non-aqueous electrolyte secondary battery includes at least the following: The spray / mixing process involves simultaneously preparing a mixture by mixing a precursor compound of the positive electrode active material with a lithium compound, and then spraying the mixture with a spray agent containing at least one element. in In the spraying / mixing process, the pressure inside the container holding the mixture and the sprayed object formed by spraying the mixture is less than atmospheric pressure.

2. The method for manufacturing the positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, characterized in that, Following the spraying / mixing process, a drying process is included, in which the sprayed material formed by spraying the mixture with the aerosol is dried.

3. The method for manufacturing the positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 2, characterized in that, In at least one of the spraying / mixing process and the drying process, the material being sprayed is heated to a maximum temperature of 40°C to 150°C.

4. The method for manufacturing the positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 or 2, characterized in that, The element is contained in the spray as a compound of that element. The amount of the compound containing the element in the spray is 8 wt% to 35 wt%.

5. The method for manufacturing the positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 or 2, characterized in that, The precursor compound contains at least nickel (Ni) and has an average secondary particle size of less than 5.5 μm.

6. The method for manufacturing the positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 or 2, characterized in that, The spray is an aqueous solution or suspension containing at least one element selected from tungsten (W), zirconium (Zr), niobium (Nb), boron (B), phosphorus (P), and molybdenum (Mo).

7. The method for manufacturing the positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 or 2, characterized in that, The spray is an aqueous solution containing tungsten (W).

8. The method for manufacturing the positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 or 2, characterized in that, The lithium compound is a powdered lithium compound.

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