Positive electrode active material for all-solid-state lithium-ion batteries, positive electrode for all-solid-state lithium-ion batteries, all-solid-state lithium-ion battery, method for producing a precursor of positive electrode active material for all-solid-state lithium-ion batteries, and method for producing positive electrode active material for all-solid-state lithium-ion batteries

Abstract

To provide a positive electrode active material for an all-solid lithium ion battery that has good discharge characteristics and energy volume density, and a manufacturing method of a precursor for a positive electrode active material for an all-solid lithium on battery that does not require a cleaning process for the positive electrode active material after firing and has good manufacturing efficiency, a manufacturing method of a positive electrode active material for an all-solid lithium ion battery, a positive electrode for an all-solid lithium ion battery using the positive electrode active material for an all-solid lithium ion battery, and an all-solid lithium ion battery.SOLUTION: A positive electrode active material for an all-solid lithium ion battery is represented by a composition formula: LiaNi(1-b-c-d)CobMncMdO2 (in the formula, M is one or more of Al and W, 0.98≤a≤1.04, 0.03≤b≤0.15, 0.02≤c≤0.08, 0≤d≤0.02). 50% cumulative volume particle size D50 is 4.0 to 7.0 μm, the tap density is 2.0 to 2.5 g / cc, the circularity is 0.88 to 0.94, the sulfate ion concentration is 1600 to 5000 wtppm, and the amount of residual alkali is 0.96% by mass or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a positive electrode active material for an all-solid-state lithium ion battery, a positive electrode for an all-solid-state lithium ion battery, an all-solid-state lithium ion battery, a method for producing a precursor of a positive electrode active material for an all-solid-state lithium ion battery, and a method for producing a positive electrode active material for an all-solid-state lithium ion battery.

Background Art

[0002] With the rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones in recent years, the development of batteries used as their power sources has been emphasized. Among these batteries, lithium ion batteries have attracted attention from the viewpoint of high energy density. In addition, for lithium ion secondary batteries for large applications such as power sources for vehicles and load leveling, improvements in energy density and battery characteristics are required.

[0003] Various materials are used as the positive electrode active material of a lithium ion secondary battery. Among them, lithium nickel oxide represented by LiNiO2 was widely used as a positive electrode active material at the beginning of the development of lithium ion secondary batteries, as described in Patent Document 1. As a method for producing a lithium nickel metal oxide having a layered rock salt structure containing nickel, it is common to synthesize a mixture of a nickel-containing hydroxide or a nickel-containing oxide and a lithium salt by firing in an oxygen atmosphere. Further, as disclosed in Patent Documents 2 and 3, a technique for removing water-soluble impurities that may adhere to the surface of the fired lithium nickel metal oxide by washing the surface with water is also known.

[0004] In the case of lithium-ion batteries, the electrolyte is mostly composed of organic compounds. Even if a flame-retardant compound is used, it cannot be said that the risk of fire is completely eliminated. As an alternative candidate for such liquid-based lithium-ion batteries, all-solid-state lithium-ion batteries with a solid electrolyte have attracted attention in recent years. Among them, all-solid-state lithium-ion batteries using sulfides such as Li2S-P2S5 as the solid electrolyte and adding lithium halide thereto are becoming the mainstream.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The battery characteristics of the positive electrode active material for all-solid-state lithium-ion batteries still have room for improvement. In particular, an improvement in the discharge capacity and the energy volume density (discharge capacity × tap density) is desired. Also, regarding the manufacturing method, in the manufacturing methods of the positive electrode active material described in Patent Documents 2 and 3, the positive electrode active material obtained after firing the precursor is washed and dried again. However, such a method increases the manufacturing cost and causes a problem of deteriorated productivity. [[ID=3​​​​​The present invention was made to solve the above-mentioned problems and aims to provide a positive electrode active material for all-solid-state lithium-ion batteries having good discharge characteristics and energy volume density. The present invention also aims to provide a method for producing a precursor of a positive electrode active material for all-solid-state lithium-ion batteries and a method for producing a positive electrode active material for all-solid-state lithium-ion batteries that does not require a cleaning step for the positive electrode active material after firing and has good manufacturing efficiency. Another objective of the present invention is to provide a positive electrode for all-solid-state lithium-ion batteries and an all-solid-state lithium-ion battery using the positive electrode active material for all-solid-state lithium-ion batteries.

[0008] Based on the above findings, the present invention is defined as follows (1) to (6). (1) Composition formula: Li a Ni (1-b-c-d) Co b Mn c M d O2 (In the above formula, M is one or more of Al and W, and the values ​​are 0.98≦a≦1.04, 0.03≦b≦0.15, 0.02≦c≦0.08, and 0≦d≦0.02.) A positive electrode active material for all-solid-state lithium-ion batteries, characterized by a 50% cumulative volume particle size D50 of 4.0 to 7.0 μm, a tap density of 2.0 to 2.5 g / cc, a circularity of 0.88 to 0.94, a sulfate ion concentration of 1600 to 5000 wt ppm, and a residual alkali content of 0.96 mass% or less. (2) BET specific surface area is 0.3~0.7m 2 A positive electrode active material for all-solid-state lithium-ion batteries as described in (1), which is / g. (3) A positive electrode for an all-solid-state lithium-ion battery comprising the positive electrode active material for all-solid-state lithium-ion batteries described in (1) or (2). (4) An all-solid-state lithium-ion battery comprising a positive electrode layer composed of the positive electrode for all-solid-state lithium-ion batteries described in (3), a negative electrode layer, and a solid electrolyte layer. (5) An aqueous solution containing any one or more of (a) nickel salt, (b) cobalt salt, (c) manganese salt, (d) aluminum salt and tungsten salt, and (e) a basic aqueous solution of ammonia water and an alkali metal is used as a reaction solution, and the pH in the reaction solution is 11.0 to 11.4, the ammonium ion concentration is 7 to 21 g / L, and the stirring power number is 3.0 to 12.0 kW / m 3 , including the step of performing a crystallization reaction while controlling the liquid temperature at 55 to 65 °C, Composition formula: Ni (1-b-c-d) Co b Mn c M d (OH)2 (In the above formula, M is any one or more of Al and W, 0.03 ≤ b ≤ 0.15, 0.02 ≤ c ≤ 0.08, 0 ≤ d ≤ 0.02.) It is represented by, the 50% cumulative volume particle size D50 is 4.0 to 6.0 μm, the circularity is 0.88 to 0.94, and the sulfate ion concentration is 1600 to 5200 wtppm. A method for producing a precursor of a positive electrode active material for an all-solid-state lithium-ion battery. (6) A precursor produced by the method for producing a precursor of a positive electrode active material for an all-solid-state lithium-ion battery described in (5) and a lithium source are mixed so that the ratio (Li n ) of the sum of the atomic numbers of the metals consisting of Ni, Co, Mn and the above M (Me n ) to the atomic number of lithium (Li n ) (Li n / Me ) is 1.01 to 1.03 to form a lithium mixture, and The step of firing the lithium mixture in an oxygen atmosphere at 450 to 520 °C for 2 to 15 hours and then firing at 680 to 850 °C for 2 to 15 hours.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a positive electrode active material for all-solid-state lithium-ion batteries having good discharge characteristics and energy volume density. Furthermore, according to the present invention, it is possible to provide a method for producing a precursor of a positive electrode active material for all-solid-state lithium-ion batteries and a method for producing a positive electrode active material for all-solid-state lithium-ion batteries that does not require a cleaning step for the positive electrode active material after firing and has good manufacturing efficiency. Furthermore, according to the present invention, it is possible to provide a positive electrode for all-solid-state lithium-ion batteries and an all-solid-state lithium-ion battery using the positive electrode active material for all-solid-state lithium-ion batteries. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of an all-solid-state lithium-ion battery according to an embodiment of the present invention. [Modes for carrying out the invention]

[0011] Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and it should be understood that appropriate design changes, improvements, etc., can be made based on the ordinary knowledge of those skilled in the art, without departing from the spirit of the invention.

[0012] (Positive electrode active material for all-solid-state lithium-ion batteries) The positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention has the compositional formula: Li a Ni (1-b-c-d) Co b Mn c M dThe positive electrode active material is represented by O2 (in the above formula, M is one or more of Al and W, with values ​​of 0.98 ≤ a ≤ 1.04, 0.03 ≤ b ≤ 0.15, 0.02 ≤ c ≤ 0.08, and 0 ≤ d ≤ 0.02). In the composition formula of the positive electrode active material, the value of a, which represents the lithium composition, is controlled to 0.98 ≤ a ≤ 1.04. Since the value of a, which represents the lithium composition, is 0.98 or higher, the reduction of nickel due to lithium deficiency can be suppressed. Furthermore, since the value of a, which represents the lithium composition, is 1.04 or lower, residual alkaline components such as lithium carbonate and lithium hydroxide present on the surface of the positive electrode active material particles, which can become a resistive component when used as a battery, can be suppressed.

[0013] The positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention has a nickel composition controlled to 1-bcd (0.75 ≤ 1-bcd ≤ 0.95) in its composition formula, and is a so-called high-nickel composition. Because the nickel composition is 0.75 or higher, a good battery capacity can be obtained for the all-solid-state lithium-ion battery.

[0014] In the embodiment of the present invention, the positive electrode active material for an all-solid-state lithium-ion battery has a composition formula where the sum of b (representing the cobalt composition), c (representing the manganese composition), and d (representing the composition of metal M (one or more of Al and W)) is 0.05 ≤ b + c + d ≤ 0.25. This improves cycle characteristics and reduces the expansion and contraction behavior of the crystal lattice due to lithium insertion and deinsertion during charging and discharging. If the sum of the cobalt composition, manganese composition, and metal M composition exceeds 0.25, the amount of cobalt, manganese, and metal M added may be too high, leading to a significant decrease in initial discharge capacity or becoming disadvantageous in terms of cost.

[0015] The positive electrode active material for an all-solid-state lithium-ion battery according to the embodiment of the present invention has a form in which a large number of primary particles are aggregated into secondary particles, and may also contain a portion of primary particles that are not aggregated as secondary particles. The shape of the primary particles constituting the secondary particles and the shape of the primary particles existing individually are not particularly limited and may be various shapes such as substantially spherical, substantially elliptical, substantially plate-shaped, or substantially needle-shaped. Furthermore, the form in which a large number of primary particles are aggregated is not particularly limited and may be various forms such as a form in which they aggregate in random directions, or a form in which they aggregate radially from the center almost uniformly to form substantially spherical or substantially elliptical secondary particles.

[0016] The positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention has a residual alkali content of 0.96% by mass or less. The residual alkali content includes lithium hydroxide and lithium carbonate, which are excess lithium generated during the manufacturing process. When the residual alkali content is 0.96% by mass or less, gas generation due to oxidative decomposition of lithium hydroxide and lithium carbonate is suppressed when the positive electrode active material is charged in a high-temperature environment. Preferably, the residual alkali content is 0.60% by mass or less. The residual alkali content can be determined by dispersing 1 g of a sample (powder) of the positive electrode active material in 50 mL of pure water, stirring for 10 minutes and filtering, and then measuring the potential difference of a mixture of 10 mL of the filtrate and 15 mL of pure water with 0.1 N HCl.

[0017] The content of lithium hydroxide and lithium carbonate in the positive electrode active material for an all-solid-state lithium-ion battery according to the embodiment of the present invention can be determined by neutralization titration. Excess lithium present on the surface of lithium metal composite oxide particles, such as lithium hydroxide and lithium carbonate, dissociates from lithium ions when dissolved in water, with hydroxide ions and carbonate ions being produced separately. These ionized anions can be titrated with an inorganic acid, thereby enabling the fractional determination of lithium hydroxide and lithium carbonate.

[0018] The moisture content in the positive electrode active material for the all-solid-state lithium-ion battery according to the embodiment of the present invention is preferably 0.10% by mass or less, and more preferably 0.05% by mass or less. If the moisture content in the positive electrode active material exceeds 0.10% by mass, it may damage the metal elements constituting the positive electrode and degrade various battery characteristics. Methods for measuring the moisture content in the positive electrode active material include the dry gravimetric method, Karl Fischer titration, and distillation.

[0019] The positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention has a 50% cumulative volume particle size D50 of 4.0 to 7.0 μm. Here, the 50% cumulative volume particle size D50 is the volume particle size at 50% accumulation in the volume-based cumulative particle size distribution curve. When the 50% cumulative volume particle size D50 of the positive electrode active material for an all-solid-state lithium-ion battery is 4.0 μm or more, the specific surface area can be suppressed and the amount of oxide coating of Li and Nb can be reduced. When the 50% cumulative volume particle size D50 of the positive electrode active material for an all-solid-state lithium-ion battery is 7.0 μm or less, it can be suppressed that the specific surface area becomes excessively small. The 50% cumulative volume particle size D50 of the positive electrode active material for an all-solid-state lithium-ion battery is more preferably 4.0 to 6.0 μm, and even more preferably 4.0 to 5.0 μm. The above method for measuring the 50% cumulative volume particle size (D50) involves first dispersing a 100 mg sample (powder) of the positive electrode active material by irradiating it with 40 W of ultrasound for 60 seconds at a 50% flow rate using a Microtrac MT3300EXII laser diffraction particle size distribution analyzer, and then measuring the particle size distribution to obtain a volume-based cumulative particle size distribution curve. Next, the volume particle size at 50% accumulation in the obtained cumulative particle size distribution curve can be used as the 50% cumulative volume particle size (D50) of the positive electrode active material powder. The water-soluble solvent used for measurement is filtered through a 0.02 μm filter, with a solvent refractive index of 1.333, particle permeability set to permeable, particle refractive index of 1.81, and non-spherical shape. The measurement range is 0.021 to 2000 μm, and the measurement time is 30 seconds.

[0020] The positive electrode active material for an all-solid-state lithium-ion battery according to the embodiment of the present invention has a tap density of 2.0 to 2.5 g / cc. When the tap density of the positive electrode active material is 2.0 g / cc or higher, a battery with a high energy density per unit volume can be constructed. The tap density of the positive electrode active material is preferably 2.1 to 2.5 g / cc, and more preferably 2.3 to 2.5 g / cc. The tap density of the positive electrode active material can be determined, for example, by putting 5 g of positive electrode active material (powder) into a 10 cc graduated cylinder, placing it in a powder density meter "KYT-4000K" manufactured by Seishin Corporation, and performing 1500 taps with a stroke length of 55 mm, after which the scale of the graduated cylinder is read. Next, "sample input amount (5 g) / graduated cylinder scale reading (cc)" is calculated and this is taken as the tap density (g / cc).

[0021] The positive electrode active material for an all-solid-state lithium-ion battery according to the embodiment of the present invention has a circularity of 0.88 to 0.94. Circularity is an index that represents how close the shape of a particle is to a sphere; for example, the circularity of a perfectly spherical particle is 1.00, which is its upper limit. When the circularity of the positive electrode active material is 0.88 or higher, the contact area between the solid electrolyte and the positive electrode active material increases, resulting in good conductivity of Li ions between the positive electrode active material and the solid electrolyte. This makes it possible to manufacture a high-capacity all-solid-state lithium-ion battery. The circularity is preferably 0.90 to 0.94, and more preferably 0.92 to 0.94. The circularity of the positive electrode active material can be measured, for example, by a particle image analyzer "Morphologi G3" manufactured by Malvern. Specifically, the circularity is measured by filtering optical images of 20,000 or more particles acquired using this particle image analyzer with a parameter of "solidity=0.93". The particle image analyzer first loads the sample (positive electrode active material) into a sample cartridge and then sets it in a dispersion unit. A nitrogen gas introduction line is connected to the dispersion unit, and nitrogen gas is blown in to disperse the sample onto a glass plate. The system continuously captures and analyzes images of the dispersed sample particles on the glass plate. Subsequently, the circularity is calculated from the projected area and perimeter of each captured particle (more than 18,000 particles) using the following formula. The average value of the circularity refers to the average of the circularity of all the positive electrode active material particles measured.

[0022] Circularity = 4πS / L 2 ···(formula) (In the above formula, S is the projected area of ​​the particle, L is the perimeter of the particle projection, and π is the ratio of a circle's circumference to its diameter.)

[0023] In an embodiment of the present invention, the positive electrode active material for an all-solid-state lithium-ion battery has a sulfate ion concentration controlled to 1600 to 5000 wt ppm. This configuration improves the conductivity of Li ions between the positive electrode active material and the solid electrolyte, resulting in excellent discharge characteristics. The amount of sulfate ions is more preferably 2000 to 4800 wt ppm. The sulfate ion concentration of the positive electrode active material is determined by quantitative analysis of sulfur using an inductively coupled plasma atomic emission spectrometer (ICP-OES) manufactured by Hitachi High-Tech Corporation, where all sulfur is oxidized to sulfate ions (SO4). 2- This can be obtained by multiplying by a coefficient, assuming that the result is .

[0024] The positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention has a BET specific surface area of ​​0.3 to 0.7 m². 2 It is preferable that the BET specific surface area is 0.3 m². 2 When the BET specific surface area is 0.7 m² or higher, the contact area between the solid electrolyte and the positive electrode active material increases, resulting in good Li ion conductivity between the positive electrode active material and the solid electrolyte. This makes it possible to manufacture high-capacity all-solid-state lithium-ion batteries. In addition, the BET specific surface area is 0.7 m². 2 If the BET specific surface area is below / g, the deposition reaction of lithium ions from residual alkali in the positive electrode active material is accelerated during repeated charging and discharging. The deposited lithium compound becomes the internal resistance of the battery, reducing the charge and discharge capacity. The BET specific surface area is 0.3 to 0.55 m². 2 / g is more preferable. The BET specific surface area can be measured by the following method. First, 1.0 g of positive electrode active material (powder) is weighed into a glass cell, set in a degasser, and the glass cell is filled with nitrogen gas. Then, it is heat-treated at 40°C for 20 minutes in a nitrogen gas atmosphere to degas it. After that, the glass cell containing the degassed sample (powder) is set into a Quantachrome specific surface area measuring device "Monosorb Model MS-21," and the specific surface area X is measured by the BET method (single-point method) while flowing a mixed gas of He:70at%-N2:30at% as the adsorption gas.

[0025] (Method for producing precursors of positive electrode active materials for all-solid-state lithium-ion batteries) Next, a method for producing a precursor of the positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention will be described in detail. The precursor of the positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention has the compositional formula: Ni (1-b-c-d) Co b Mn c M d The material is represented by (OH)2 (wherein M is one or more of Al and W, 0.03≦b≦0.15, 0.02≦c≦0.08, 0≦d≦0.02), has a 50% cumulative volume particle size D50 of 4.0~6.0 μm, a circularity of 0.88~0.94, and a sulfate ion concentration of 1600~5200 wtppm. The method for producing a precursor of a positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention is to first prepare an aqueous solution containing (a) a nickel salt, (b) a cobalt salt, (c) a manganese salt, (d) one or more of an aluminum salt and a tungsten salt, and (e) a basic aqueous solution of ammonia water and an alkali metal. Examples of (a) nickel salts include nickel sulfate, nickel nitrate, or nickel hydrochloride. Examples of (b) cobalt salts include cobalt sulfate, cobalt nitrate, or cobalt hydrochloride. (c) Examples of manganese salts include manganese sulfate, manganese nitrate, or manganese hydrochloride. (d) Examples of aluminum salts include aluminum sulfate, aluminum nitrate, or sodium aluminate. Examples of tungsten salts include sodium tungstate, tungsten chloride, or potassium tungstate. (e) Examples of basic aqueous solutions containing ammonia include aqueous ammonia solution, ammonium sulfate, ammonium carbonate, and ammonium hydrochloride. Basic aqueous solutions of alkali metals may also be aqueous solutions of sodium hydroxide, potassium hydroxide, carbonates, etc. Examples of aqueous solutions of carbonates include aqueous solutions of sodium carbonate, aqueous potassium carbonate, aqueous sodium bicarbonate, and aqueous potassium bicarbonate, which are aqueous solutions of carbonate groups.

[0026] Furthermore, the composition of the aqueous solution can be appropriately adjusted depending on the composition of the precursor to be produced, but it is preferable that it is (a) an aqueous solution containing 45 to 110 g / L of nickel ions, (b) an aqueous solution containing 4 to 20 g / L of cobalt ions, (c) an aqueous solution containing 1 to 4 g / L of manganese ions, (d) an aqueous solution containing 13 to 90 g / L of aluminum and / or tungsten, (e) an aqueous ammonia solution of 7 to 28% by mass, and a basic aqueous solution with an alkali metal concentration of 10 to 30% by mass.

[0027] Next, an aqueous solution containing one or more of the above-mentioned (a) nickel salt, (b) cobalt salt, (c) manganese salt, (d) aluminum salt and tungsten salt, and (e) a basic aqueous solution of ammonia water and an alkali metal is used as the reaction solution, with the pH of the reaction solution set to 11.0-11.4, the ammonium ion concentration to 7-21 g / L, and the stirring power to 3.0-12.0 kW / m 3 The crystallization reaction is carried out while controlling the liquid temperature to 55-65°C. At this time, the chemical solutions may be supplied to the reaction vessel from three tanks: a tank containing a mixed aqueous solution of one or more of nickel salts, cobalt salts, manganese salts, aluminum salts, and tungsten salts; a tank containing ammonia water; and a tank containing a basic aqueous solution with an alkali metal. The pH of the reaction solution during the coprecipitation reaction should be 11.0-11.4, the ammonium ion concentration 7-21 g / L, and the stirring power 3.0-12.0 kW / m 3 By controlling the liquid temperature to 55-65°C while performing the crystallization reaction, the solubility of the metal in the reaction solution can be increased, allowing for the production of particles in which aluminum and tungsten are uniformly dispersed, thus enabling the creation of a precursor for positive electrode active material with good discharge characteristics. Furthermore, by optimizing the reaction conditions of the metal hydroxide precursor as described above, the adhesion of impurities to the surface of the positive electrode active material obtained after calcination is effectively suppressed, eliminating the need for washing. In addition, chelating agents and metal oxide coatings during the coprecipitation reaction become unnecessary. As a result, manufacturing efficiency is improved.

[0028] Here, the "stirring power" mentioned above refers to the stirring power in a reaction vessel equipped with a stirring blade. The stirring power is set to 3.0 kW / m 3By doing so, aggregation of fine particles during eutectic precipitation can be prevented. The stirring power should be 12.0 kW / m². 3 By following the instructions below, particle breakage can be suppressed and the spherical shape can be maintained. The stirring power should be 3.0 to 5.5 kW / m². 3 It is more preferable that this is the case. In addition, the rotation speed of the impeller can be adjusted as appropriate according to the target stirring power, but it is typically 800 to 1300 rpm.

[0029] (Method for manufacturing positive electrode active material for all-solid-state lithium-ion batteries) Next, a method for producing a positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention will be described in detail. In a method for producing a positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention, first, a lithium source is added to the precursor of the positive electrode active material for an all-solid-state lithium-ion battery, and the sum of the number of atoms of the metals Ni, Co, Mn and M (Me n ) and the number of lithium atoms (Li n ) ratio (Li n / Me n The mixture is formed by mixing the materials so that the ratio is 1.01 to 1.03. Examples of lithium sources include lithium carbonate or lithium hydroxide. As for the mixing method, it is preferable to adjust the mixing ratio of each raw material and dry mix them using a Henschel mixer, automatic mortar and pestle, or V-type mixer.

[0030] Next, the lithium mixture is calcined in an oxygen atmosphere at 450-520°C for 2-15 hours, and then further calcined at 680-850°C for 2-15 hours. After that, if necessary, the calcined body can be crushed using, for example, a pulverizer to obtain the positive electrode active material powder.

[0031] Conventionally, after calcining the precursor, it is necessary to wash it with water to remove water-soluble impurities that may adhere to the surface of the lithium nickel metal oxide after calcination. However, in the method for producing a positive electrode active material for an all-solid-state lithium-ion battery according to the embodiment of the present invention, the adhesion of impurities to the surface of the positive electrode active material after calcination can be effectively suppressed. Therefore, the positive electrode active material produced by the method for producing a positive electrode active material for an all-solid-state lithium-ion battery according to the embodiment of the present invention does not require a washing step after calcination. Consequently, the manufacturing efficiency is improved.

[0032] Furthermore, when a coating layer is to be provided on the surface of the positive electrode active material, the coating treatment shown below can be performed. First, the surface of the powder of the positive electrode active material is coated with a coating solution. In this case, the coating solution can be, for example, a solution containing LiOC2H5 and Nb(OC2H5)5 when the coating layer is composed of lithium niobate. Also, a known coating apparatus, such as a rolling fluidized bed coating apparatus, can be used for the coating method. In this way, the surface of the positive electrode active material can be coated with lithium niobate or the like.

[0033] (Positive electrode for all-solid-state lithium-ion batteries and all-solid-state lithium-ion batteries) A positive electrode can be formed using a positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention, and this positive electrode can be used as the positive electrode layer. An all-solid-state lithium-ion battery can be manufactured comprising this positive electrode layer, a solid electrolyte layer, and a negative electrode layer. The solid electrolyte layer and negative electrode layer constituting the all-solid-state lithium-ion battery according to an embodiment of the present invention are not particularly limited and can be formed from known materials, and can have known configurations as shown in Figure 1.

[0034] The positive electrode layer of the lithium-ion battery can be made by forming a positive electrode composite material in layers, which is obtained by mixing the positive electrode active material for all-solid-state lithium-ion batteries according to the present invention with a solid electrolyte. The content of the positive electrode active material in the positive electrode layer is preferably 50% by mass or more and 99% by mass or less, and more preferably 60% by mass or more and 90% by mass or less.

[0035] The positive electrode composite may further contain a conductive additive. This conductive additive may be a carbon material, a metallic material, or a mixture thereof. The conductive additive may include, for example, at least one element selected from the group consisting of carbon, nickel, copper, aluminum, indium, silver, cobalt, magnesium, lithium, chromium, gold, ruthenium, platinum, beryllium, iridium, molybdenum, niobium, osnium, rhodium, tungsten, and zinc. The conductive additive is preferably a highly conductive element of carbon, a metallic element, mixture, or compound containing carbon, nickel, copper, silver, cobalt, magnesium, lithium, ruthenium, gold, platinum, niobium, osnium, or rhodium. As carbon materials, for example, carbon black such as Ketjenblack, acetylene black, Denka black, thermal black, and channel black, graphite, carbon fiber, activated carbon, etc., can be used.

[0036] The average thickness of the positive electrode layer of a lithium-ion battery is not particularly limited and can be designed appropriately depending on the purpose. For example, the average thickness of the positive electrode layer of a lithium-ion battery may be 1 μm to 100 μm, or 1 μm to 10 μm.

[0037] The method for forming the positive electrode layer of a lithium-ion battery is not particularly limited and can be appropriately selected depending on the purpose. Examples of methods for forming the positive electrode layer of a lithium-ion battery include compression molding of positive electrode active material particles.

[0038] The negative electrode layer of a lithium-ion battery may be formed by layering a known negative electrode active material for all-solid-state lithium-ion batteries. Alternatively, the negative electrode layer may be formed by layering a negative electrode composite material obtained by mixing a known negative electrode active material for lithium-ion batteries with a solid electrolyte. The content of the negative electrode active material in the negative electrode layer is preferably, for example, 10% by mass or more and 99% by mass or less, and more preferably 20% by mass or more and 90% by mass or less.

[0039] The negative electrode layer, like the positive electrode layer, may contain a conductive additive. The conductive additive may be the same material as the material described for the positive electrode layer. As the negative electrode active material, for example, carbon materials, specifically artificial graphite, graphite carbon fiber, resin-calcined carbon, pyrolysis vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-calcined carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon, or mixtures thereof, can be used. Furthermore, as the negative electrode material, for example, metallic lithium, metallic indium, metallic aluminum, metallic silicon, or alloys combined with other elements or compounds can be used.

[0040] The average thickness of the negative electrode layer of a lithium-ion battery is not particularly limited and can be appropriately selected depending on the purpose. For example, the average thickness of the negative electrode layer of a lithium-ion battery may be 1 μm to 100 μm, or 1 μm to 10 μm.

[0041] The method for forming the negative electrode layer of a lithium-ion battery is not particularly limited and can be appropriately selected depending on the purpose. Examples of methods for forming the negative electrode layer of a lithium-ion battery include a method of compression molding of negative electrode active material particles and a method of vapor deposition of negative electrode active material.

[0042] A known solid electrolyte for all-solid-state lithium-ion batteries can be used as the solid electrolyte. Oxide-based solid electrolytes or sulfide-based solid electrolytes, etc., can be used as the solid electrolyte.

[0043] Examples of oxide-based solid electrolytes include LiTi2(PO4)3, Li2O-B2O3-P2O5, Li2O-SiO2, Li2O-B2O3, and Li2O-B2O3-ZnO.

[0044] Examples of sulfide-based solid electrolytes include LiI-Li2S-P2S5, LiI-Li2S-B2S3, Li3PO4-Li2S-Si2S, Li3PO4-Li2S-SiS2, LiPO4-Li2S-SiS, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li3PS4, and Li2S-P2S5.

[0045] Examples of solid electrolytes using lithium-containing compounds that include lithium and at least one element selected from niobium, tantalum, silicon, phosphorus, and boron include LiNbO3, or Li 1.3 Al 0.3 Ti 0.7 (PO4)3, Li 1+x+y A x Ti 2-x Si y P 3-y O 12 (A=Al or Ga, 0≦x≦0.4, 0 <y≦0.6)、[(B 1 / 2 Li 1 / 2 ) 1-z C z ]TiO3(B=La, Pr, Nd, Sm, C=Sr or Ba, 0≦x≦0.5), Li5La3Ta2O 12 Li7La3Zr2O 12 Li6BaLa2Ta2O 12 Li3PO (4-3 / 2w) N w (w<1), and Li 3.6 Si 0.6 P 0.4 Examples include O4, as well as LiI, LiI-Al2O3, LiN3, and Li3N-LiI-LiOH.

[0046] The average thickness of the solid electrolyte layer of a lithium-ion battery is not particularly limited and can be designed appropriately depending on the purpose. For example, the average thickness of the solid electrolyte layer of a lithium-ion battery may be 50 μm to 500 μm, or 50 μm to 100 μm.

[0047] The method for forming the solid electrolyte layer of a lithium-ion battery is not particularly limited and can be appropriately selected depending on the purpose. Examples of methods for forming the solid electrolyte layer of a lithium-ion battery include sputtering using a target material for the solid electrolyte, or compression molding of the solid electrolyte.

[0048] Other components constituting the lithium-ion battery are not particularly limited and can be appropriately selected depending on the purpose. Examples include a positive electrode current collector, a negative electrode current collector, and a battery case.

[0049] The size and structure of the positive electrode current collector are not particularly limited and can be appropriately selected according to the purpose. Examples of materials for the positive electrode current collector include die steel, stainless steel, aluminum, aluminum alloy, titanium alloy, copper, gold, and nickel. Possible shapes for the positive electrode current collector include foil-like, plate-like, and mesh-like forms. The average thickness of the positive electrode current collector may be, for example, 10 μm to 500 μm, or 50 μm to 100 μm.

[0050] The size and structure of the negative electrode current collector are not particularly limited and can be appropriately selected according to the purpose. Examples of materials for the negative electrode current collector include die steel, gold, indium, nickel, copper, and stainless steel. Examples of negative electrode current collector shapes include foil-like, plate-like, and mesh-like shapes. The average thickness of the negative electrode current collector may be, for example, 10 μm to 500 μm, or 50 μm to 100 μm.

[0051] The battery case is not particularly limited and can be selected as appropriate depending on the purpose. Examples include known laminate films that can be used with conventional solid-state batteries. Examples of laminate films include resin laminate films and films in which metal has been vapor-deposited onto a resin laminate film. The shape of the battery is not particularly limited and can be selected as appropriate depending on the purpose. Examples include cylindrical, rectangular, button-shaped, coin-shaped, and flat-shaped batteries. [Examples]

[0052] The following examples are provided to better understand the present invention and its advantages, but the present invention is not limited to these examples.

[0053] (Example 1) First, nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts to obtain a Ni:Co:Mn ratio of 82:15:3, and a 1.5 mol / L mixed metal salt solution was prepared. Next, the mixed metal salt solution, ammonia water, and a 20% by mass sodium hydroxide aqueous solution were introduced into a reaction vessel equipped with a stirring blade, so that the pH of the reaction vessel was 11.1 and the ammonium ion concentration was 15.0 g / L. A crystallization reaction was then carried out to precipitate a nickel-cobalt-manganese complex hydroxide compound. At this time, the rotation speed of the reaction vessel's stirring blade was set to 1000 rpm and the stirring power to 5.5 kW / m 3 The temperature was controlled and maintained at 60°C using a water jacket. Furthermore, nitrogen gas was introduced into the reaction vessel to prevent oxidation of the coprecipitate produced in the crystallization reaction. The gas introduced into the reaction vessel is not limited to nitrogen gas; any gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide, can be used. Next, the obtained precipitate was filtered by suction, washed with water, and dried in a box-type dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material. Next, when the sum of the number of atoms of the metal precursor consisting of Ni, Co, and Mn is defined as Me, the ratio of lithium (Li) atoms to Me (Li / Me) is 1.01. The lithium hydroxide and the precursor of the positive electrode active material are mixed and mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder is filled into an alumina mortar and fired in a muffle furnace under an oxygen atmosphere at 500°C for 4 hours, then heated to 740°C and held at that temperature for 8 hours to obtain the positive electrode active material.

[0054] (Example 2) Nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts to obtain a Ni:Co:Mn ratio of 86:7:7, and a 1.5 mol / L mixed metal salt solution was prepared. A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that the ammonium ion concentration was set to 17.8 g / L under crystallization reaction conditions. Next, the cathode active material was prepared by mixing lithium hydroxide and a precursor of the cathode active material in the same manner as in Example 1 and then firing the mixture.

[0055] (Example 3) Nickel sulfate, cobalt sulfate, manganese sulfate, and sodium aluminate were weighed in predetermined amounts to prepare a 1.5 mol / L mixed metal salt solution with a ratio of Ni:Co:Mn:Al = 85:7:7:1. A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that the ammonium ion concentration was 20 g / L and the pH was 11.0 under crystallization reaction conditions. Next, the cathode active material was prepared by mixing lithium hydroxide and a precursor of the cathode active material in the same manner as in Example 1 and then firing the mixture.

[0056] (Example 4) Nickel sulfate, cobalt sulfate, manganese sulfate, and sodium tungstate were weighed in predetermined amounts to prepare a 1.5 mol / L mixed metal salt solution with a ratio of Ni:Co:Mn:W = 81.4:14.9:3.0:0.7. A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that the ammonium ion concentration was 21 g / L and the pH was 11.0 under crystallization reaction conditions. Next, a positive electrode active material was prepared by calcining in the same manner as in Example 1, except that lithium hydroxide and a precursor of the positive electrode active material were mixed so that the ratio of lithium (Li) atoms (Li / Me) was 1.03.

[0057] (Example 5) Nickel sulfate, cobalt sulfate, manganese sulfate, and sodium tungstate were weighed in predetermined amounts to prepare a 1.5 mol / L mixed metal salt solution with a ratio of Ni:Co:Mn:W = 81.4:14.9:3.0:0.7. A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that the ammonium ion concentration was 21 g / L and the pH was 11.0 under crystallization reaction conditions. Next, the cathode active material was prepared by mixing lithium hydroxide and a precursor of the cathode active material in the same manner as in Example 1 and then firing the mixture.

[0058] (Example 6) Nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts to obtain a Ni:Co:Mn ratio of 82:15:3, and a 1.5 mol / L mixed metal salt solution was prepared. A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that the ammonium ion concentration was 13.5 g / L and the pH was 11.2 under crystallization reaction conditions. Next, the cathode active material was prepared by mixing lithium hydroxide and a precursor of the cathode active material in the same manner as in Example 1 and then firing the mixture.

[0059] (Example 7) Nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts to achieve a ratio of Ni:Co:Mn = 90:7:3, and a 1.5 mol / L mixed metal salt solution was prepared. Under crystallization reaction conditions, the ammonium ion concentration was 7.2 g / L, the pH was 11.0, the reaction vessel's impeller rotation speed was 820 rpm, and the stirring power was 3.0 kW / m 3 A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that it was controlled to the same extent. Next, the lithium hydroxide and the precursor of the positive electrode active material were mixed and calcined in the same manner as in Example 1, except that the calcination temperature was heated to 720°C, to produce the positive electrode active material.

[0060] (Example 8) Nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts to achieve a ratio of Ni:Co:Mn = 90:7:3, and a 1.5 mol / L mixed metal salt solution was prepared. Under crystallization reaction conditions, the ammonium ion concentration was 10 g / L, the pH was 11.0, the reaction vessel's impeller rotation speed was 820 rpm, and the stirring power was 3.0 kW / m 3 A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that it was controlled to the same extent. Next, lithium hydroxide and the precursor of the positive electrode active material were mixed so that the ratio of lithium (Li) atoms (Li / Me) was 0.98, and the mixture was fired in the same manner as in Example 1, except that it was heated to a firing temperature of 720°C.

[0061] (Example 9) A 1.5 mol / L mixed metal salt solution was prepared by weighing predetermined amounts of nickel sulfate, cobalt sulfate, and manganese sulfate so that Ni:Co:Mn = 90:7:3. Under crystallization reaction conditions, the ammonium ion concentration was 17.4 g / L, the pH was 11.2, the reaction vessel's impeller rotation speed was 1300 rpm, and the stirring power was 12.0 kW / m 3 A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that it was controlled to the same extent. Next, lithium hydroxide and the precursor of the positive electrode active material were mixed so that the ratio of lithium (Li) atoms (Li / Me) was 1.03, and the mixture was fired in the same manner as in Example 1, except that it was heated to a firing temperature of 720°C.

[0062] (Example 10) Nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts to achieve a ratio of Ni:Co:Mn = 90:7:3, and a 1.5 mol / L mixed metal salt solution was prepared. Under crystallization reaction conditions, the reaction vessel temperature was maintained at 55°C, the ammonium ion concentration was 14.6 g / L, the pH was 11.4, the reaction vessel's impeller rotation speed was 1300 rpm, and the stirring power was 12.0 kW / m 3 A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that it was controlled to the same extent. Next, lithium hydroxide and the precursor of the positive electrode active material were mixed so that the ratio of lithium (Li) atoms (Li / Me) was 1.03, and the mixture was fired in the same manner as in Example 1, except that it was heated to a firing temperature of 720°C.

[0063] (Comparative Example 1) Nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts to achieve a ratio of Ni:Co:Mn = 90:7:3, and a 1.5 mol / L mixed metal salt solution was prepared. Under crystallization reaction conditions, the reaction vessel liquid temperature was maintained at 50°C, the ammonium ion concentration was 4.1 g / L, the pH was 11.3, the reaction vessel's impeller rotation speed was 820 rpm, and the stirring power was 3.0 kW / m 3 A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that it was controlled to the same extent. Next, the lithium hydroxide and the precursor of the positive electrode active material were mixed and calcined in the same manner as in Example 1, except that the calcination temperature was heated to 720°C, to produce the positive electrode active material.

[0064] (Comparative Example 2) Nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts to achieve a ratio of Ni:Co:Mn = 90:7:3, and a 1.5 mol / L mixed metal salt solution was prepared. Under crystallization reaction conditions, the ammonium ion concentration was 4.6 g / L, the pH was 11.0, the reaction vessel's impeller rotation speed was 820 rpm, and the stirring power was 3.0 kW / m 3 A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that it was controlled to the same extent. Next, the cathode active material was prepared by mixing lithium hydroxide and a precursor of the cathode active material in the same manner as in Example 1 and then firing the mixture.

[0065] (Comparative Example 3) Nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts to achieve a ratio of Ni:Co:Mn = 90:7:3, and a 1.5 mol / L mixed metal salt solution was prepared. Under crystallization reaction conditions, the ammonium ion concentration was 8.0 g / L, the pH was 10.9, the reaction vessel's impeller rotation speed was 820 rpm, and the stirring power was 3.0 kW / m 3A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that it was controlled to the same extent. Next, the lithium hydroxide and the precursor of the positive electrode active material were mixed and calcined in the same manner as in Example 1, except that the calcination temperature was heated to 720°C, to produce the positive electrode active material.

[0066] (Comparative Example 4) Nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts to achieve a ratio of Ni:Co:Mn = 90:7:3, and a 1.5 mol / L mixed metal salt solution was prepared. Under crystallization reaction conditions, the ammonium ion concentration was 8.2 g / L, the pH was 11.2, the reaction vessel's impeller rotation speed was 500 rpm, and the stirring power was 1.9 kW / m 3 A precursor for the positive electrode active material was prepared in the same manner as in Example 1, except that it was controlled to the same extent. Next, lithium hydroxide and the precursor of the positive electrode active material were mixed so that the ratio of lithium (Li) atoms (Li / Me) was 1.03, and the mixture was fired in the same manner as in Example 1, except that it was heated to a firing temperature of 720°C.

[0067] <Rating> (composition) A specified amount of each obtained precursor and each cathode active material sample (powder) was weighed out, decomposed by alkaline fusion, and then its composition was analyzed using a Hitachi High-Tech inductively coupled plasma atomic emission spectrometer (ICP-OES) "PS7800".

[0068] (50% cumulative volume particle size D50) 100 mg samples (powder) of each obtained precursor and each cathode active material were dispersed by irradiating with 40 W ultrasonic waves for 60 seconds at a 50% flow rate using a Microtrac MT3300EXII laser diffraction particle size distribution analyzer. The particle size distribution was then measured to obtain a volume-based cumulative particle size distribution curve. In the obtained cumulative particle size distribution curve, the volume particle size at 50% accumulation was defined as the 50% cumulative volume particle size D50 of the cathode active material powder. The water-soluble solvent used for measurement was passed through a 0.02 μm filter, with a solvent refractive index of 1.333, particle permeability conditions of transmission, particle refractive index of 1.81, and non-spherical shape. The measurement range was 0.021 to 2000 μm, and the measurement time was 30 seconds.

[0069] (Tap density) 5g samples (powder) of each obtained precursor and each cathode active material were placed in a 10cc graduated cylinder and placed in a powder density meter "KYT-4000K" manufactured by Seishin Corporation. After 1500 taps with a stroke length of 55mm, the scale of the graduated cylinder was read. Next, the "sample input amount (5g) / graduated cylinder scale reading (cc)" was calculated and defined as the tap density (g / cc).

[0070] (Circularity) Each of the obtained precursors and cathode active material samples (powder) were measured using a Malvern Morphologi G3 particle image analyzer. Specifically, the circularity was measured by filtering the optical images of more than 20,000 particles obtained with the particle image analyzer using a parameter of "solidity=0.93". The particle image analyzer first loaded the sample (precursor, cathode active material) into a sample cartridge and then set it in the dispersion unit. Next, a nitrogen gas introduction line was connected to the dispersion unit, and the sample was dispersed onto a glass plate by blowing nitrogen gas into it. After continuously capturing and analyzing particle images of the dispersed sample on the glass plate, the circularity was calculated from the projected area and perimeter of each captured particle (more than 18,000 particles) using the following formula. The average value of the circularity refers to the average of the circularity of all the cathode active material particles measured.

[0071] Circularity = 4πS / L 2 ···(formula) (In the above formula, S is the projected area of ​​the particle, L is the perimeter of the particle projection, and π is the ratio of a circle's circumference to its diameter.)

[0072] (BET specific surface area) 1.0 g of each obtained precursor and each cathode active material sample (powder) was weighed into a glass cell, placed in a degasser, filled with nitrogen gas, and then heat-treated at 40°C for 20 minutes in a nitrogen gas atmosphere to degas it. After that, the glass cell containing the degassed sample (powder) was placed in a Quantachrome Monosorb Model MS-21 specific surface area analyzer, and the specific surface area X was measured by the BET method (single-point method) while flowing a mixed gas of He:70at%-N2:30at% as the adsorption gas.

[0073] (Sulfate ion concentration) The sulfur content of each obtained precursor and each cathode active material sample (powder) was quantitatively analyzed using an inductively coupled plasma atomic emission spectrometer (ICP-OES) manufactured by Hitachi High-Tech Corporation. All the sulfur was oxidized to sulfate ions (SO4). 2- This was obtained by multiplying by the coefficient, assuming that the result would be ).

[0074] (Residual alkali) One g of each positive electrode active material sample (powder) was dispersed in 50 mL of pure water, stirred for 10 minutes, and filtered. The mixture of 10 mL of the filtrate and 15 mL of pure water was then measured for potential difference using 0.1 N HCl to determine the potential difference.

[0075] (Battery characteristics) The following all-solid-state battery cells were fabricated in a glove box under an argon atmosphere. First, each sample was coated with LiOC2H5 and Nb(OC2H5)5 respectively, and then fired at 400°C for 1 hour in an oxygen atmosphere to produce a cathode active material with an amorphous lithium niobate layer on its surface. Next, 75 mg of the positive electrode active material and 25 mg of the sulfide-based solid electrolyte material Li3PS were mixed to obtain a positive electrode composite material. Furthermore, 480 mg of the sulfide-based solid electrolyte material Li3PS was pressed at a pressure of 5 MPa using a pellet molding machine to form a solid electrolyte layer. 10 mg of the positive electrode composite material was placed on top of this solid electrolyte layer and pressed at a pressure of 30 MPa to produce a composite material layer. Next, the composite layer of the obtained solid electrolyte layer and positive electrode active material layer was flipped over, and a SUS plate with a Li foil (5 mm diameter x 0.1 mm thickness) attached to it was placed on the solid electrolyte layer side, and pressed under a pressure of 20 MPa to form the Li negative electrode layer. In this way, a laminate was fabricated in which the positive electrode active material layer, solid electrolyte layer, and Li negative electrode layer were stacked in this order. Next, the laminate was placed in a SUS304 battery test cell and constrained to create an all-solid-state secondary battery, and the initial characteristics (discharge capacity) of the battery at 25°C were measured. The energy volume density (discharge capacity × tap density) was also calculated. The charge and discharge conditions were as follows: Charging conditions: CC / CV 4.2V, 0.1C; Discharge conditions: CC 0.05C, up to 3.0V. The above manufacturing conditions and test results are shown in Tables 1 and 2.

[0076] [Table 1]

[0077] [Table 2]

[0078] <Evaluation Results> The positive electrode active material in Examples 1 to 10 all has the composition formula: Li a Ni (1-b-c-d) Co b Mn c M dThe material was represented as O2 (in the above formula, M is one or more of Al and W, with 0.98≦a≦1.04, 0.03≦b≦0.15, 0.02≦c≦0.08, and 0≦d≦0.02), and had a 50% cumulative volume particle size D50 of 4.0~7.0 μm, a tap density of 2.0~2.5 g / cc, a circularity of 0.88~0.94, a sulfate ion concentration of 1600~5000 wtppm, and a residual alkali content of 0.96 mass% or less, resulting in good discharge capacity and energy volume density. Comparative Example 1 had a residual alkali content outside the range of 0.96% by mass or less, and a sulfate ion concentration outside the range of 1600 to 5000 wt ppm. As a result, its discharge capacity was inferior to that of Examples 7 and 8, which had a Ni composition ratio of approximately 90 mol%. Comparative Example 2 had poor energy volume density because its tap density was outside the range of 2.0 to 2.5 g / cc, its circularity was outside the range of 0.88 to 0.94, its residual alkali content was outside the range of 0.96 mass% or less, and its sulfate ion concentration was outside the range of 1600 to 5000 wt ppm. Comparative Example 3 had poor energy volume density because its tap density was outside the range of 2.0 to 2.5 g / cc and its circularity was outside the range of 0.88 to 0.94. Comparative Example 4 had poor energy volume density because its tap density was outside the range of 2.0 to 2.5 g / cc, its circularity was outside the range of 0.88 to 0.94, and its sulfate ion concentration was outside the range of 1600 to 5000 wt ppm.

Claims

1. Composition formula: Li a Ni (1-b-c-d) Co b Mn c M d O 2 (In the above formula, M is one or more of Al and W, and 0.98 ≤ a ≤ 1.04, 0.03 ≤ b ≤ 0.15, 0.02 ≤ c ≤ 0.08, and 0 ≤ d ≤ 0.02.) A positive electrode active material for all-solid-state lithium-ion batteries, characterized by a 50% cumulative volume particle size D50 of 4.0 to 7.0 μm, a tap density of 2.0 to 2.5 g / cc, a circularity of 0.88 to 0.94, a sulfate ion concentration of 1600 to 5000 wt ppm, and a residual alkali content of 0.96 mass% or less.

2. BET specific surface area is 0.3 to 0.7 m² 2 The positive electrode active material for an all-solid-state lithium-ion battery according to claim 1, wherein the value is / g.

3. A positive electrode for an all-solid-state lithium-ion battery, comprising the positive electrode active material for an all-solid-state lithium-ion battery described in claim 1 or 2.

4. An all-solid-state lithium-ion battery comprising a positive electrode layer composed of the positive electrode for an all-solid-state lithium-ion battery described in claim 3, a negative electrode layer, and a solid electrolyte layer.

5. The reaction solution is an aqueous solution containing (a) nickel salt, (b) cobalt salt, (c) manganese salt, and (e) a basic aqueous solution of ammonia water and an alkali metal, with the pH of the reaction solution set to 11.0 to 11.4, the ammonium ion concentration to 7 to 21 g / L, and the stirring power to 3.0 to 12.0 kW / m 3 The process includes a step of carrying out a crystallization reaction while controlling the liquid temperature to 55-65°C. Composition formula: Ni (1-bc) Co b Mn c (OH) 2 (In the above formula, 0.03 ≤ b ≤ 0.15 and 0.02 ≤ c ≤ 0.08.) A method for producing a precursor of a positive electrode active material for all-solid-state lithium-ion batteries, wherein the precursor is expressed as follows, has a 50% cumulative volume particle size D50 of 4.0 to 6.0 μm, a circularity of 0.88 to 0.94, and a sulfate ion concentration of 1600 to 5200 wt ppm.

6. A precursor produced by the method for producing a precursor of a positive electrode active material for an all-solid-state lithium ion battery according to claim 5, and a lithium source are combined such that the ratio of the sum of the number of atoms of metals consisting of Ni, Co, and Mn (Me n ), to the number of atoms of lithium (Li n ), (Li n / Me n ) is 1.01 to 1.03, to form a lithium mixture; The lithium mixture is calcined in an oxygen atmosphere at 450-520°C for 2-15 hours, and then further calcined at 680-850°C for 2-15 hours. A method for producing a positive electrode active material for all-solid-state lithium-ion batteries, including the material itself.

7. A crystallization reaction is carried out using an aqueous solution containing (a) a nickel salt, (b) a cobalt salt, (c) a manganese salt, (d) one or more of an aluminum salt and a tungsten salt, and (e) a basic aqueous solution of ammonia water and an alkali metal as the reaction solution, while controlling the pH of the reaction solution to 11.0 to 11.4, the ammonium ion concentration to 7 to 21 g / L, the stirring power to 3.0 to 12.0 kW / m³, and the liquid temperature to 55 to 65°C. Composition formula: Ni (1-bcd) Co b Mn c M d (OH) 2 (In the above formula, M is one or more of Al and W, 0.03 ≤ b ≤ 0.15, 0.02 ≤ c ≤ 0.08, and 0 < d ≤ 0.02.) A method for producing a precursor of a positive electrode active material for all-solid-state lithium-ion batteries, wherein the precursor is expressed as follows, has a 50% cumulative volume particle size D50 of 4.0 to 6.0 μm, a circularity of 0.88 to 0.94, and a sulfate ion concentration of 1600 to 5200 wt ppm.

8. A step of forming a lithium mixture by mixing a precursor produced by the method for producing a positive electrode active material precursor for an all-solid-state lithium-ion battery described in Claim 7 with a lithium source such that the ratio of the sum of the number of atoms of the metals consisting of Ni, Co, Mn and the aforementioned M (Men) to the number of atoms of lithium (LiN) (LiN / Men) is 1.01 to 1.03, The lithium mixture is calcined in an oxygen atmosphere at 450-520°C for 2-15 hours, and then further calcined at 680-850°C for 2-15 hours. A method for producing a positive electrode active material for all-solid-state lithium-ion batteries, including the material itself.

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