Cubic li-la-zr-al composite oxide powder

Abstract

Disclosed is a cubic Li-La-Zr-Al composite oxide powder which contains 85 mass% or more of a cubic Li-La-Zr-Al composite oxide component, has a BET specific surface area of 0.15 2 / g or more, and has an average displacement strength of 50.0 MPa or less as measured by an average displacement strength measurement test. According to the present invention, it is possible to provide a cubic Li-La-Zr-Al composite oxide powder having good pulverability.

Description

Cubic Li-La-Al composite oxide powder

[0001] The present invention relates to a cubic Li-La-Zr-Al composite oxide powder mainly containing a cubic Li-La-Zr-Al composite oxide component.

[0002] As a solid electrolyte used for solid batteries (particularly all-solid-state batteries), Li ７ La ３ Zr ２ O １２ Li-La-Zr-based composite oxide powders having a basic composition of (hereinafter sometimes referred to as "LLZ-based composite oxide powders") are known.

[0003] In addition, it is known that the crystal structure of this Li-La-Zr-based composite oxide (hereinafter sometimes referred to as "LLZ-based composite oxide") mainly has two types: tetragonal and cubic. For applications in solid batteries, it is known that cubic crystals with high lithium ion conductivity are preferred.

[0004] However, cubic Li ７ La ３ Zr ２ O １２ is not stable at normal temperature, so various studies have been conducted so far to produce cubic Li-La-Zr-based composite oxides that exist stably at normal temperature.

[0005] For example, Patent Document 1 discloses the following method. First, lithium carbonate, lanthanum hydroxide, and zirconium oxide are mixed, placed in an alumina crucible, heated at a rate of 600°C per hour, and held at 900°C for 6 hours. Thereafter, about half by weight of the portion of the obtained powder that was in contact with the alumina crucible is removed, and the powder not in contact with the crucible is recovered, then pulverized with a pounder for 30 minutes, placed in the alumina crucible again, heated at 600°C per hour, and held at 1125°C for 6 hours to obtain a powder. Thereafter, about half by weight of the portion of the powder that was in contact with the alumina crucible is further removed, and the powder not in contact with the crucible is recovered. After sieving this powder, with respect to this powder, Al ２ O ３The mixture is thoroughly mixed with the added ingredients, and the resulting mixed powder is press-molded into pellets using a mold. These pellets are then embedded in the mixed powder and heated at 60°C / hour, and held at 1180°C for 36 hours to obtain a Li-La-Zr-Al composite oxide.

[0006] Furthermore, Patent Document 1 also discloses the following method. First, lithium hydroxide, lanthanum hydroxide, and zirconium oxide are mixed and placed in an alumina crucible, the temperature is raised to 600°C / hour, and then held at 900°C for 6 hours. After that, the obtained powder is mixed with pebbles and pulverized using a vibrating mill for 3 hours, then sieved, and then γ-Al ２ O ３ The mixture is mixed with other materials, then press-molded into pellets using a mold. These pellets are placed on an alumina setter, and the setter is placed inside an alumina scabbard. The mixture is heated at 200°C / hour and held at 1000°C for 36 hours to obtain a Li-La-Zr-Al composite oxide.

[0007] Furthermore, Patent Document 1 also discloses the following method. First, lithium hydroxide, lanthanum hydroxide, and zirconium oxide are mixed and placed in an alumina crucible, the temperature is raised to 600°C / hour, and then held at 900°C for 6 hours. The resulting powder is then mixed with γ-Al ２ O ３ The following steps are performed: adding the powder and mixing it with pebbles, grinding it using a vibratory mill for 3 hours, sieving it further, then press-molding it using a mold to form pellets, placing these pellets on an alumina setter, putting the setter and pellets into an alumina sieve, heating it at 200°C / hour, and holding it at 1000°C for 36 hours to obtain a Li-La-Zr-Al composite oxide.

[0008] Furthermore, for example, Patent Document 1 discloses a ceramic material containing lithium (Li), lanthanum (La), zirconium (Zr), oxygen (O), and aluminum (Al).

[0009] Japanese Patent Publication No. 2011-051800

[0010] In recent years, there has been a demand for LLZ-based composite oxide powders with a high content of cubic LLZ-based composite oxides and fine particle sizes of 30 to 300 nm. Therefore, the present inventors attempted to produce LLZ-based composite oxides (pellets) using the method described in Patent Document 1 and to pulverize the oxides, but were unable to pulverize them successfully.

[0011] Therefore, the inventors mixed Li-containing raw materials, La-containing raw materials, Zr-containing raw materials, and Al-containing raw materials to form a raw material composition, and produced LLZ-based composite oxide powder by calcining the raw material composition at a relatively low temperature of 1050°C. Although it was possible to pulverize it well, the cubic LLZ-based composite oxide content of the LLZ-based composite oxide powder was low. Consequently, when the aforementioned raw material composition was calcined at a high temperature of 1150°C to produce LLZ-based composite oxide powder, although the content of cubic LLZ-based composite oxide increased, it was not possible to pulverize it well.

[0012] In other words, there was a trade-off between producing a powder with a high content of cubic LLZ-based composite oxides and grinding the LLZ-based composite oxide powder to a good degree.

[0013] Therefore, the present invention aims to provide a cubic Li-La-Zr-Al composite oxide powder with good pulverability.

[0014] As a result of diligent research to solve the above problems, the present inventors have found the following and completed the present invention. (1) Although the addition of Al to the raw materials for manufacturing LLZ composite oxides has been practiced conventionally, the molar ratio of Al to La constituting the LLZ composite oxide (Al / La) is preferably around 0.07 to 0.08 or less, and it was known that if there is too much Al, the lithium ion conductivity decreases, as described in Patent Document 1. In fact, when the present inventors actually manufactured LLZ composite oxides by heating the raw materials containing Li, La, Zr, and Al at a low temperature of 1050°C or less or relatively low temperature without adjusting the type, decomposition temperature or melting point, particle size, etc., in compositions with a high Al content, a large amount of La-Li-Al composite oxide was produced, and as a result, the content of cubic Li-La-Zr-Al composite oxide was low. (2) On the other hand, when Li-containing raw materials, La-containing raw materials, Zr-containing raw materials, and Al-containing raw materials are heated at high temperatures such as 1150°C without adjusting the type, decomposition temperature or melting point, particle size, etc., as in the conventional method, the content of cubic Li-La-Zr-Al composite oxide increases, but the sintering or fusion of the product particles progresses, and the particle size of the composite oxide becomes larger. Furthermore, the composite oxide particles that are excessively sintered or fused have poor pulverability, and when pulverization is performed to reduce the particle size, it is not possible to pulverize them to an appropriate size, and extremely fine particles are generated during pulverization. (3) Compared to these prior arts, the inventors have found that in the production of cubic Li-La-Zr-Al composite oxide with a high Al content, the types, decomposition temperature or melting point, particle size, etc. of the Li-containing raw materials, La-containing raw materials, Zr-containing raw materials, and Al-containing raw materials are adjusted, and the mixture of these raw materials is heated at a low temperature of 1050°C or lower or a relatively low temperature, and an appropriate amount of a precursor-containing composition containing La-Li-Al composite oxide is generated during the heating process, and the content of cubic Li-La-Zr-Al composite oxide can be increased by heating the resulting precursor-containing composition.Furthermore, the inventors have found that by heating the raw material mixture at a low or relatively low temperature, a cubic Li-La-Zr-Al composite oxide can be obtained, and a cubic Li-La-Zr-Al composite oxide powder with gradual sintering or fusion of composite oxide particles can be obtained. (4) The inventors have also found that the cubic Li-La-Zr-Al composite oxide powder with gradual sintering or fusion of particles has good pulverability, making it easy to pulverize to an appropriate size, and that extremely fine particles are less likely to be generated during pulverization.

[0015] In other words, the present invention (1) is a cubic Li-La-Zr-Al composite oxide powder in which the content of the cubic Li-La-Zr-Al composite oxide component is 85% by mass or more of the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, as calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method, and the BET specific surface area is 0.15 m². ２ The present invention provides a cubic Li-La-Zr-Al composite oxide powder characterized by having a concentration of 1 / g or more, and the average displacement strength of the powder, as measured by the average displacement strength measurement test described below, being 50.0 MPa or less. <Average Displacement Strength Measurement Test> Cubic Li-La-Zr-Al composite oxide powder is scattered on the lower pressure plate made of SKS steel of a microcompression testing machine. Ten particles with a diameter of 15 μm or more and 50 μm or less are randomly selected from the scattered powder. For each selected particle, a load of up to 1000 mN is applied to the particle up to 1000 mN using the microcompression testing machine at 25°C in an atmospheric environment, with a diamond upper pressure indenter having a circular flat section with a diameter of 200 μm, at a loading speed of 207 mN / sec in the vertical direction. When the load at which a 10% displacement occurs is P (N) and the particle diameter at which a 10% displacement occurs is d (mm), the displacement strength St (MPa) is calculated using the following formula (1), and the arithmetic mean of the obtained values ​​for the 10 points is taken as the average displacement strength (MPa). Displacement strength St = 2.8P / πd ２ (1)

[0016] Furthermore, the present invention (2) is a cubic Li-La-Zr-Al composite oxide powder in which the content of the cubic Li-La-Zr-Al composite oxide component is 85% by mass or more of the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, as calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method, and the BET specific surface area is 0.15 m². ２ The present invention provides a cubic Li-La-Zr-Al composite oxide powder characterized by having a concentration of 1 / g or more, satisfying at least one of the following: (i) the average displacement strength of the powder measured by the average displacement strength measurement test described below is 50.0 MPa or less, and (ii) the ratio of the number of moles of Al on an atomic basis to the number of moles of La on an atomic basis (Al / La) is 0.17 or more and 0.40 or less. <Average Displacement Strength Measurement Test> Cubic Li-La-Zr-Al composite oxide powder is scattered on the lower pressure plate made of SKS steel of a microcompression testing machine. Ten particles with a diameter of 15 μm or more and 50 μm or less are randomly selected from the scattered powder. For each selected particle, a load of up to 1000 mN is applied to the particle up to 1000 mN using the microcompression testing machine at 25°C in an atmospheric environment, with a diamond upper pressure indenter having a circular flat section with a diameter of 200 μm, at a loading speed of 207 mN / sec in the vertical direction. When the load at which a 10% displacement occurs is P (N) and the particle diameter at which a 10% displacement occurs is d (mm), the displacement strength St (MPa) is calculated using the following formula (1), and the arithmetic mean of the obtained values ​​for the 10 points is taken as the average displacement strength (MPa). Displacement strength St = 2.8P / πd ２ (1)

[0017] Furthermore, the present invention (3) is a cubic Li-La-Zr-Al composite oxide powder in which the content of the cubic Li-La-Zr-Al composite oxide component is 85% by mass or more of the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, as calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method, and the BET specific surface area is 0.15 m². ２ The present invention provides a cubic Li-La-Zr-Al composite oxide powder of type (2), characterized in that the amount is 1 / g or more, and the ratio of the number of moles of Al on an atomic basis to the number of moles of La on an atomic basis (Al / La) is 0.17 or more and 0.40 or less.

[0018] Furthermore, the present invention (4) provides a cubic Li-La-Zr-Al composite oxide powder according to any of (1) to (3), characterized in that the sample standard deviation calculated from 10 displacement strength St values ​​obtained in the average displacement strength measurement test is 50.0 MPa or less.

[0019] Furthermore, the present invention (5) provides a cubic Li-La-Zr-Al composite oxide powder according to (1), characterized in that the ratio of the number of moles of Al on an atomic basis to the number of moles of La on an atomic basis (Al / La) is 0.17 or more and 0.40 or less.

[0020] Furthermore, the present invention (6) provides a cubic Li-La-Zr-Al composite oxide powder according to any of (1) to (5), characterized in that the content of the cubic Li-La-Zr-Al composite oxide component is 90% by mass or more.

[0021] Furthermore, the present invention (7) provides a cubic Li-La-Zr-Al composite oxide powder according to any of (1) to (6), characterized in that it is for use in solid-state batteries.

[0022] Furthermore, the present invention (8) provides a cubic Li-La-Zr-Al composite oxide powder according to any of (1) to (7), characterized in that it is for use as a separator in a solid-state battery.

[0023] Furthermore, the present invention (9) provides a ceramic slurry comprising any of (1) to (8) cubic Li-La-Zr-Al composite oxide powder or pulverized thereof, and a solvent.

[0024] Furthermore, the present invention (10) provides a method for producing a ceramic slurry, which includes the step of grinding any of the cubic Li-La-Zr-Al composite oxide powders described in (1) to (8).

[0025] According to the present invention, it is possible to provide a cubic Li-La-Zr-Al composite oxide powder with good pulverability.

[0026] These are scanning electron microscope images of Experimental Examples 3-8. These are scanning electron microscope images of Experimental Examples 9-14. These are scanning electron microscope images of Experimental Examples 15-20. These are scanning electron microscope images of Experimental Examples 21-26. These are scanning electron microscope images of Experimental Examples 27-32.

[0027] The cubic Li-La-Zr-Al composite oxide powder of the present invention will be described below. In the present invention, the cubic Li-La-Zr-Al composite oxide is an oxide composed of the elements Li, La, Zr, and Al, and is preferably represented by formula (2) described below. In the present invention, the La-Li-Al composite oxide is an oxide composed of the elements La, Li, and Al, and is preferably represented by formula (4) described below.

[0028] The cubic Li-La-Zr-Al composite oxide powder of the present invention is a cubic Li-La-Zr-Al composite oxide powder in which the content of the cubic Li-La-Zr-Al composite oxide component is 85% by mass or more of the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, as calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method, and the BET specific surface area is 0.15 m². ２The cubic Li-La-Zr-Al composite oxide powder is characterized by having a concentration of 1 / g or more, and satisfying at least one of the following: (i) the average displacement strength of the powder measured by the average displacement strength measurement test described below is 50.0 MPa or less, and (ii) the ratio of the number of moles of Al on an atomic basis to the number of moles of La on an atomic basis (Al / La) is 0.17 or more and 0.45 or less, preferably 0.17 or more and 0.40 or less. <Average Displacement Strength Measurement Test> Cubic Li-La-Zr-Al composite oxide powder is scattered on the lower pressure plate made of SKS steel of a microcompression testing machine. Ten particles with a diameter of 15 μm or more and 50 μm or less are randomly selected from the scattered powder. For each selected particle, a load of up to 1000 mN is applied to the particle up to 1000 mN using the microcompression testing machine at 25°C in an atmospheric environment, with a diamond upper pressure indenter having a circular flat section with a diameter of 200 μm, at a loading speed of 207 mN / sec in the vertical direction. When the load at which a 10% displacement occurs is P (N) and the particle diameter at which a 10% displacement occurs is d (mm), the displacement strength St (MPa) is calculated using the following formula (1), and the arithmetic mean of the obtained values ​​for the 10 points is taken as the average displacement strength (MPa). Displacement strength St = 2.8P / πd ２ (1)

[0029] In other words, the cubic Li-La-Zr-Al composite oxide powder of the present invention satisfies (i), or (ii), or both (i) and (ii).

[0030] The cubic Li-La-Zr-Al composite oxide powder of the present invention preferably satisfies (i). That is, a preferred embodiment of the cubic Li-La-Zr-Al composite oxide powder of the present invention is a cubic Li-La-Zr-Al composite oxide powder in which the content of the cubic Li-La-Zr-Al composite oxide component in the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method, is 85% by mass or more, and the BET specific surface area is 0.15 m². ２The cubic Li-La-Zr-Al composite oxide powder is characterized by having a concentration of 1 / g or more, and (i) the average displacement strength of the powder measured by the average displacement strength measurement test described below being 50.0 MPa or less. <Average Displacement Strength Measurement Test> Cubic Li-La-Zr-Al composite oxide powder is scattered on the lower pressure plate made of SKS steel of a microcompression testing machine. Ten particles with a diameter of 15 μm or more and 50 μm or less are randomly selected from the scattered powder. For each selected particle, a load of up to 1000 mN is applied to the particle up to 1000 mN using the microcompression testing machine at 25°C in an atmospheric environment, with a diamond upper pressure indenter having a circular flat section with a diameter of 200 μm, at a loading speed of 207 mN / sec in the vertical direction. When the load at which a 10% displacement occurs is P (N) and the particle diameter at which a 10% displacement occurs is d (mm), the displacement strength St (MPa) is calculated using the following formula (1), and the arithmetic mean of the obtained values ​​for the 10 points is taken as the average displacement strength (MPa). Displacement strength St = 2.8P / πd ２ (1)

[0031] Furthermore, the cubic Li-La-Zr-Al composite oxide powder of the present invention preferably satisfies (ii). That is, a preferred embodiment of the cubic Li-La-Zr-Al composite oxide powder of the present invention is a cubic Li-La-Zr-Al composite oxide powder in which the content of the cubic Li-La-Zr-Al composite oxide component in the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method, is 85% by mass or more, and the BET specific surface area is 0.15 m². ２ The cubic Li-La-Zr-Al composite oxide powder is characterized by having a concentration of 1 / g or more, and (ii) having a ratio of the number of moles of Al on an atomic basis to the number of moles of La on an atomic basis (Al / La) of 0.17 or more and 0.45 or less, preferably 0.17 or more and 0.40 or less.

[0032] Furthermore, it is particularly preferable that the cubic Li-La-Zr-Al composite oxide powder of the present invention satisfies both (i) and (ii). That is, a particularly preferred embodiment of the cubic Li-La-Zr-Al composite oxide powder of the present invention is a cubic Li-La-Zr-Al composite oxide powder in which the content of the cubic Li-La-Zr-Al composite oxide component in the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method, is 85% by mass or more, and the BET specific surface area is 0.15 m². ２ This is a cubic Li-La-Zr-Al composite oxide powder characterized by having a concentration of 1 / g or more, satisfying both of the following: (i) the average displacement strength of the powder measured by the average displacement strength measurement test described below is 50.0 MPa or less, and (ii) the ratio of the number of moles of Al on an atomic basis to the number of moles of La on an atomic basis (Al / La) is 0.17 or more and 0.45 or less, preferably 0.17 or more and 0.40 or less. <Average Displacement Strength Measurement Test> Cubic Li-La-Zr-Al composite oxide powder is scattered on the lower pressure plate made of SKS steel of a microcompression testing machine. Ten particles with a diameter of 15 μm or more and 50 μm or less are randomly selected from the scattered powder. For each selected particle, a load of up to 1000 mN is applied to the particle up to 1000 mN using the microcompression testing machine at 25°C in an atmospheric environment, with a diamond upper pressure indenter having a circular flat section with a diameter of 200 μm, at a loading speed of 207 mN / sec in the vertical direction. When the load at which a 10% displacement occurs is P (N) and the particle diameter at which a 10% displacement occurs is d (mm), the displacement strength St (MPa) is calculated using the following formula (1), and the arithmetic mean of the obtained values ​​for the 10 points is taken as the average displacement strength (MPa). Displacement strength St = 2.8P / πd ２ (1)

[0033] As shown in Figures 1 to 5, the cubic Li-La-Zr-Al composite oxide powder of the present invention is composed of particle bonds in which multiple cubic Li-La-Zr-Al composite oxide particles are sintered or fused together. In other words, the cubic Li-La-Zr-Al composite oxide powder of the present invention is an aggregate of bonded products in which multiple cubic Li-La-Zr-Al composite oxide particles are bonded together by sintering or fusion.

[0034] The cubic Li-La-Zr-Al composite oxide powder of the present invention mainly contains cubic Li-La-Zr-Al composite oxide. In the cubic Li-La-Zr-Al composite oxide powder of the present invention, the "content of the cubic Li-La-Zr-Al composite oxide component in the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method" (hereinafter sometimes referred to as the "cubic Li-La-Zr-Al composite oxide component content") is 85% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Furthermore, the upper limit can be 100% by mass or less. By having a cubic Li-La-Zr-Al composite oxide component content within the above range, the lithium ion conductivity can be increased when a sintered body is formed using the powder of the present invention.

[0035] In the present invention, the method for calculating the content of cubic Li-La-Zr-Al composite oxide components is as follows. First, using an XRD measuring device (for example, SmartLab manufactured by Rigaku Corporation), an XRD measurement is performed using CuKα rays (wavelength λ: 1.5418 Å) under the conditions of tube voltage 40 kV, tube current 25 mA, step angle 0.0152°, and scanning speed 10° / min, for diffraction angles 2θ: 15° to 80°. Next, using analysis software (for example, Rigaku Integrated Powder X-ray Analysis Software PDXL), cubic Li-La-Zr-Al composite oxide, tetragonal Li-La-Zr composite oxide, La-Li-Al composite oxide, lanthanum aluminate, lithium zirconate, lithium aluminate, and lanthanum zirconate are selected as the target components for analysis. The RIR (Reference Intensity Ratio) method is used to calculate the mass ratio of each component to the total of the target components from the integrated intensity of the strongest diffraction peak of each component.

[0036] Furthermore, while a higher content of the cubic Li-La-Zr-Al composite oxide component in the cubic Li-La-Zr-Al composite oxide powder of the present invention is preferable, it may also contain tetragonal Li-La-Zr composite oxide components as long as it does not impair the effects of the present invention. In the cubic Li-La-Zr-Al composite oxide powder of the present invention, the "content of the tetragonal Li-La-Zr composite oxide component in the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method" (hereinafter sometimes referred to as the "tetragonal Li-La-Zr composite oxide component content") is preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 1% by mass or less. Furthermore, the cubic Li-La-Zr-Al composite oxide powder of the present invention may contain by-products or unreacted raw materials, etc., to the extent that the effects of the present invention are not impaired. For example, the content of components other than the cubic Li-La-Zr-Al composite oxide component and the tetragonal Li-La-Zr composite oxide component in the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method, is preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 1% by mass or less.

[0037] In the cubic Li-La-Zr-Al composite oxide powder of the present invention, the stoichiometric composition of the cubic Li-La-Zr-Al composite oxide is given by the following formula (2): Li ｘ１ Al ｘ２ La ｘ３ Zr ｘ４ O ｘ５(2) Preferably, it is a cubic Li-La-Zr-Al composite oxide represented by formula (2) (wherein x1 is 5.0 or more and 9.0 or less, x2 is 0.01 or more and 1.5 or less, x3 is 1.5 or more and 4.0 or less, x4 is 0.1 or more and 4.0 or less, and x5 is 9.0 or more and 15.0 or less).

[0038] In formula (2), x1 is preferably 5.5 to 8.5, more preferably 6.0 to 8.0. In formula (2), x2 is preferably 0.05 to 1.0, more preferably 0.1 to 0.75. In formula (2), x3 is preferably 2.0 to 3.75, more preferably 2.5 to 3.5. In formula (2), x4 is preferably 0.5 to 3.5, more preferably 1.0 to 3.0. In formula (2), x5 is preferably 10.0 to 14.0, more preferably 11.0 to 13.0. Note that in formula (2), elements other than those mentioned above may be used, as long as they do not impair the effects of the present invention. ｘ６ It may also include. In formula (2), x6 is preferably 0.0 or more and 0.1 or less.

[0039] Furthermore, the tetragonal Li-La-Zr composite oxide is given by the following formula (3): Li ｙ１ La ｙ２ Zr ｙ３ O ｙ４ (3) (In formula (3), y1 is 5.0 or more and 9.0 or less, preferably 5.5 or more and 8.5 or less, more preferably 6.0 or more and 8.0 or less, and particularly preferably 7.0; y2 is 1.5 or more and 4.0 or less, preferably 2.0 or more and 3.75 or less, more preferably 2.5 or more and 3.5 or less, and particularly preferably 3.0; y3 is 0.1 or more and 4.0 or less, preferably 0.5 or more and 3.5 or less, more preferably 1.0 or more and 3.0 or less, and particularly preferably 2.0; y4 is 9.0 or more and 15.0 or less, preferably 10.0 or more and 14.0 or less, more preferably 11.0 or more and 13.0 or less, and particularly preferably 12.0.)

[0040] Furthermore, the La-Li-Al composite oxide is given by the following formula (4): La ｐ１ Li ｐ２ Al ｐ３ Oｐ４ (4) (In formula (4), p1 is 1.0 or more and 3.0 or less, preferably 1.3 or more and 2.7 or less, more preferably 1.6 or more and 2.4 or less, and particularly preferably 2.0; p2 is 0.2 or more and 0.8 or less, preferably 0.3 or more and 0.7 or less, more preferably 0.4 or more and 0.6 or less, and particularly preferably 0.5; p3 is 0.2 or more and 0.8 or less, preferably 0.3 or more and 0.7 or less, more preferably 0.4 or more and 0.6 or less, and particularly preferably 0.5; and p4 is 2.0 or more and 6.0 or less, preferably 3.0 or more and 5.0 or less, more preferably 3.5 or more and 4.5 or less, and particularly preferably 4.0.)

[0041] Furthermore, lanthanum aluminate is given by the following formula (5): La ｑ１ Al ｑ２ O ｑ３ (5) (In formula (5), q1 is 0.5 or more and 1.5 or less, preferably 0.8 or more and 1.2 or less, particularly preferably 1.0; q2 is 0.5 or more and 1.5 or less, preferably 0.8 or more and 1.2 or less, particularly preferably 1.0; and q3 is 1.5 or more and 4.5 or less, preferably 2.4 or more and 3.6 or less, particularly preferably 3.0.)

[0042] Furthermore, lithium zirconate is given by the following formula (6): Li ｒ１ Zr ｒ２ O ｒ３ (6) (In formula (6), r1 is 1.0 or more and 3.0 or less, preferably 1.6 or more and 2.4 or less, particularly preferably 2.0; r2 is 0.5 or more and 1.5 or less, preferably 0.8 or more and 1.2 or less, particularly preferably 1.0; and r3 is 1.5 or more and 4.5 or less, preferably 2.4 or more and 3.6 or less, particularly preferably 3.0.)

[0043] Furthermore, lithium aluminate is given by the following formula (7): Li ｓ１ Al ｓ２ O ｓ３(7) (In formula (7), s1 is 0.5 or more and 1.5 or less, preferably 0.8 or more and 1.2 or less, particularly preferably 1.0; s2 is 0.5 or more and 1.5 or less, preferably 0.8 or more and 1.2 or less, particularly preferably 1.0; s3 is 1.0 or more and 3.0 or less, preferably 1.6 or more and 2.4 or less, particularly preferably 2.0.) Lanthanum zirconate is represented by the following formula (8): La ｔ１ Zr ｔ２ O ｔ３ (8) (In formula (8), t1 is 1.0 or more and 3.0 or less, preferably 1.6 or more and 2.4 or less, particularly preferably 2.0; t2 is 1.0 or more and 3.0 or less, preferably 1.6 or more and 2.4 or less, particularly preferably 2.0; t3 is 3.5 or more and 10.5 or less, preferably 5.6 or more and 8.4 or less, particularly preferably 7.0.)

[0044] Furthermore, formulas (3) to (8) may include elements other than those mentioned above, to the extent that they do not impair the effects of the present invention. ｚ It may further include the following. In formulas (3) to (8), z is preferably 0.0 or more and 0.1 or less.

[0045] The cubic Li-La-Zr-Al composite oxide powder of the present invention preferably (ii) has a ratio of the number of moles of Al (Al / La) on an atomic basis to the number of moles of La (La) on an atomic basis, which is 0.17 or more and 0.45 or less, preferably 0.17 or more and 0.40 or less, preferably 0.25 or more and 0.40 or less, more preferably 0.28 or more and 0.35 or less, and particularly preferably 0.31 or more and 0.35 or less. When the ratio of the number of moles of Al (Al / La) on an atomic basis to the number of moles of La (La) on an atomic basis in the cubic Li-La-Zr-Al composite oxide powder is within the above range, the content of the cubic Li-La-Zr-Al composite oxide component tends to be higher, and the pulverability is improved, making it easier to pulverize to an appropriate size and making it difficult to generate extremely fine particles during pulverization.

[0046] In the cubic Li-La-Zr-Al composite oxide powder of the present invention, the ratio of the number of moles of Li (on an atomic basis) to the number of moles of La (on an atomic basis) (Li / La) is preferably 2.00 or more and 2.67 or less, more preferably 2.17 or more and 2.50 or less. Having the ratio of the number of moles of Li (on an atomic basis) to the number of moles of La (on an atomic basis) in the cubic Li-La-Zr-Al composite oxide powder within the above range makes it easier to increase the content of the cubic Li-La-Zr-Al composite oxide component, thus making it easier to obtain excellent electrical properties when molded into sheets or the like.

[0047] In the cubic Li-La-Zr-Al composite oxide powder of the present invention, the ratio of the number of moles of Zr (on an atomic basis) to the number of moles of La (on an atomic basis) (Zr / La) is preferably 0.40 or more and 1.00 or less, more preferably 0.50 or more and 0.83 or less. Having the ratio of the number of moles of Zr (on an atomic basis) to the number of moles of La (on an atomic basis) in the cubic Li-La-Zr-Al composite oxide powder within the above range makes it easier to suppress the formation of by-products, thus making it easier to obtain excellent electrical properties when molded into sheets or the like.

[0048] In the cubic Li-La-Zr-Al composite oxide powder of the present invention, the Li element content determined by ICP analysis is preferably 4.0% by mass or more and 7.0% by mass or less, more preferably 4.5% by mass or more and 6.5% by mass or less; the La element content is preferably 30% by mass or more and 60% by mass or less, more preferably 35% by mass or more and 55% by mass or less; the Zr element content is preferably 10% by mass or more and 30% by mass or less, more preferably 15% by mass or more and 25% by mass or less; and the Al element content is preferably 0.5% by mass or more and 5.0% by mass or less, more preferably 1.0% by mass or more and 4.5% by mass or less.

[0049] The volume-based cumulative 50% particle size (D50) of the cubic Li-La-Zr-Al composite oxide powder of the present invention, as measured by laser diffraction scattering, is preferably 0.1 μm to 150 μm, more preferably 0.1 μm to 100 μm, more preferably 0.1 μm to 50 μm, more preferably 0.5 μm to 40 μm, more preferably 1.0 μm to 30 μm, more preferably 1.0 μm to 20 μm, and particularly preferably 1.0 μm to 10 μm.

[0050] The BET specific surface area of ​​the cubic Li-La-Zr-Al composite oxide powder of the present invention is 0.15 m². ２ / g or more, preferably 0.20m ２ / g or more, more preferably 0.25m ２ / g or more, more preferably 0.30m ２ / g or more, more preferably 0.40m ２ / g or more, particularly preferably 0.50m ２ It is 1 / g or more. The particle bond of the cubic Li-La-Zr-Al composite oxide particles constituting the cubic Li-La-Zr-Al composite oxide powder of the present invention has a structure in which the cubic Li-La-Zr-Al composite oxide particles are loosely sintered or fused. In such a structure in which the cubic Li-La-Zr-Al composite oxide particles are loosely sintered or fused, there are gaps in the particle bond to some extent and / or the shape of the particles before sintering or fusion is retained to some extent, so the BET specific surface area is larger compared to a structure in which the composite oxide particles are excessively sintered or fused. In other words, the BET specific surface area of ​​the cubic Li-La-Zr-Al composite oxide powder of the present invention is 0.15 m². ２ / g or more, preferably 0.20m ２ / g or more, more preferably 0.25m ２ / g or more, more preferably 0.30m ２ / g or more, more preferably 0.40m ２ / g or more, particularly preferably 0.50m ２The fact that it is 1 / g or more indicates that the particle bonds of the cubic Li-La-Zr-Al composite oxide constituting the cubic Li-La-Zr-Al composite oxide powder of the present invention are formed by loose sintering or fusion of particles, and that there are gaps within the particle bonds to some extent and / or that the structure retains the shape of the particles to some extent before sintering or fusion. Furthermore, the BET specific surface area is 1.00 m². ２ It is preferable that the amount is less than or equal to / g. This suppresses the reaction between the powder and air, thereby suppressing the formation of reactants on the powder surface and reducing gas generation during firing in the sheet formation process. This suppresses crack formation during firing and makes it easier to form a dense fired film. The BET specific surface area in this invention can be measured by the method described in the "Measurement of BET Specific Surface Area" section of the examples described later.

[0051] The cubic Li-La-Zr-Al composite oxide powder of the present invention preferably has an average displacement strength of 50.0 MPa or less, preferably 45.0 MPa or less, more preferably 40.0 MPa or less, more preferably 35.0 MPa or less, more preferably 30.0 MPa or less, more preferably 25.0 MPa or less, and particularly preferably 20.0 MPa or less, as measured by an average displacement strength measurement test. The lower limit of the average displacement strength is not particularly limited, but for example, it is greater than 0.0 MPa. The bonded structure of the cubic Li-La-Zr-Al composite oxide particles constituting the cubic Li-La-Zr-Al composite oxide powder of the present invention has a structure in which gaps exist to some extent in the particle bonded structure and / or retains to some extent the shape of the particles before sintering or fusing. Therefore, the average displacement strength of the powder measured by the average displacement strength measurement test is smaller compared to a structure in which the composite oxide particles are excessively sintered or fused. In other words, the fact that the average displacement strength of the powder measured by the average displacement strength measurement test of the cubic Li-La-Zr-Al composite oxide powder of the present invention is 50.0 MPa or less, preferably 45.0 MPa or less, more preferably 40.0 MPa or less, more preferably 35.0 MPa or less, more preferably 30.0 MPa or less, more preferably 25.0 MPa or less, and particularly preferably 20.0 MPa or less indicates that the particle binders of the cubic Li-La-Zr-Al composite oxide constituting the cubic Li-La-Zr-Al composite oxide powder of the present invention have a structure in which gaps exist to a certain extent within the particle binders and / or retain to a certain extent the shape of the particles before sintering or fusion.

[0052] Based on these findings, the BET specific surface area of ​​the cubic Li-La-Zr-Al composite oxide powder of the present invention is 0.15 m². ２ / g or more, preferably 0.20m ２ / g or more, more preferably 0.25m ２ / g or more, more preferably 0.30m ２ / g or more, more preferably 0.40m ２ / g or more, particularly preferably 0.50m ２The fact that the amount is 1 / g or more, and (i) the average displacement strength of the powder measured by the average displacement strength measurement test is 50.0 MPa or less, preferably 45.0 MPa or less, more preferably 40.0 MPa or less, more preferably 35.0 MPa or less, more preferably 30.0 MPa or less, more preferably 25.0 MPa or less, and particularly preferably 20.0 MPa or less, indicates that the cubic Li-La-Zr-Al composite oxide powder of the present invention has a structure in which the particle binders constituting the powder have gaps within the particle binders to some extent and / or retain to some extent the shape of the particles before sintering or fusing, that is, it has a structure in which the particles are loosely sintered or fused together. Furthermore, in the cubic Li-La-Zr-Al composite oxide powder of the present invention, since the particle binders constituting the powder have a structure in which gaps within the particle binders to some extent and / or retain to some extent the shape of the particles before sintering or fusing, it has good pulverability, and therefore it is easy to pulverize to the desired size, and it is difficult to generate extremely fine particles during pulverization.

[0053] The cubic Li-La-Zr-Al composite oxide powder of the present invention has a sample standard deviation calculated from 10 displacement intensity St values ​​obtained in an average displacement intensity measurement test of 50.0 MPa or less, preferably 45.0 MPa or less, more preferably 40.0 MPa or less, more preferably 35.0 MPa or less, more preferably 30.0 MPa or less, more preferably 25.0 MPa or less, and more preferably 20.0 MPa or less. The lower limit of the sample standard deviation is not particularly limited, but for example, it is greater than 0.0 MPa. Because the sample standard deviation calculated from 10 displacement strength St values ​​obtained in the average displacement strength measurement test of the cubic Li-La-Zr-Al composite oxide powder falls within the above range, the variation in the "structure in which there are gaps to some extent within the particle bond and / or which retains the shape of the particles to some extent before sintering or fusion" for each particle bond of the cubic Li-La-Zr-Al composite oxide constituting the cubic Li-La-Zr-Al composite oxide of the present invention is reduced, resulting in better pulverability. Therefore, it is easier to pulverize to the desired size, and extremely fine particles are less likely to be generated during pulverization.

[0054] The average displacement strength measurement test in this invention is as follows: Cubic Li-La-Zr-Al composite oxide powder is scattered on the lower pressure plate made of SKS steel of a micro-compression testing machine. Ten particles with a diameter of 15 μm or more and 50 μm or less are randomly selected from the scattered powder. For each selected particle, a load of up to 1000 mN is applied to the particle using the micro-compression testing machine at 25°C in an atmospheric environment, using a diamond upper pressure indenter with a circular flat section having a diameter of 200 μm, at a loading speed of 207 mN / sec in the vertical direction. When the load at which a 10% displacement occurs is P (N) and the particle diameter at which a 10% displacement occurs is d (mm), the displacement strength St (MPa) is calculated using the following formula (1). The arithmetic mean of the 10 obtained values ​​is taken as the average displacement strength (MPa). The sample standard deviation is then calculated for the 10 obtained displacement strength St (MPa) values. Displacement strength St = 2.8P / πd ２ (1) Note that SKS steel is an alloy of carbon steel to which W, Mo, Cr, V, etc. are added.

[0055] Furthermore, the BET specific surface area of ​​the cubic Li-La-Zr-Al composite oxide powder of the present invention is 0.15 m². ２ / g or more, preferably 0.20m ２ / g or more, more preferably 0.25m ２ / g or more, more preferably 0.30m ２ / g or more, more preferably 0.40m ２ / g or more, particularly preferably 0.50m ２The amount is 1 / g or more, and (ii) in the cubic Li-La-Zr-Al composite oxide powder of the present invention, the ratio of the number of moles of Al on an atomic basis to the number of moles of La on an atomic basis (Al / La) is 0.17 or more and 0.45 or less, preferably 0.17 or more and 0.40 or less, preferably 0.25 or more and 0.40 or less, more preferably 0.28 or more and 0.35 or less, and particularly preferably 0.31 or more and 0.35 or less, so that the particles in the particle binder constituting the powder have a structure in which there are gaps to some extent and / or retain to some extent the shape of the particles before sintering or fusing, that is, the particle binder has a structure in which the particles are loosely sintered or fused together. Therefore, the cubic Li-La-Zr-Al composite oxide powder of the present invention has better pulverability, making it easier to pulverize to the desired size, and also resulting in a cubic Li-La-Zr-Al composite oxide powder that is less likely to generate extremely fine particles during pulverization.

[0056] The cubic Li-La-Zr-Al composite oxide powder of the present invention has good pulverability, so when pulverized to a desired particle size, extremely fine particles are less likely to be generated. When manufacturing a solid electrolyte layer using the cubic Li-La-Zr-Al composite oxide powder, the cubic Li-La-Zr-Al composite oxide powder is pulverized to the desired particle size, and then the resulting pulverized material is mixed with a binder resin and, if necessary, other additives to form a resin composition. After forming the resin composition into layers, the solid electrolyte layer is manufactured by firing. At this time, if there are many extremely fine particles in the pulverized cubic Li-La-Zr-Al composite oxide powder, a large amount of binder resin will be required, making it difficult to remove the binder resin during firing, and thus making it difficult to form a dense film. Also, if there are many extremely fine particles, the viscosity of the resin composition slurry becomes too high, resulting in poor printability. Furthermore, extremely fine particles are prone to aggregation and are difficult to disperse. Furthermore, the more extremely fine particles there are, the wider the particle size distribution becomes, leading to greater variation in the sintering of the solid electrolyte layer. The cubic Li-La-Zr-Al composite oxide powder of the present invention does not easily generate extremely fine particles when pulverized to the desired size, thus eliminating the need to use a large amount of binder resin. Therefore, it prevents the difficulty in removing the binder resin during firing caused by the use of a large amount of resin binder, making it easier to form a dense solid electrolyte layer. Also, because the cubic Li-La-Zr-Al composite oxide powder of the present invention does not easily generate extremely fine particles during pulverization, the viscosity of the resin composition slurry does not become excessively high, resulting in good printability. Furthermore, because the cubic Li-La-Zr-Al composite oxide powder of the present invention does not easily generate extremely fine particles during pulverization, the stability of the resin composition can be improved. Additionally, because the cubic Li-La-Zr-Al composite oxide powder of the present invention does not easily generate extremely fine particles during pulverization, it is less prone to aggregation and easily dispersed. Furthermore, the cubic Li-La-Zr-Al composite oxide powder of the present invention can reduce the amount of extremely fine particles after grinding, thereby preventing the particle size distribution from becoming wider due to the presence of extremely fine particles, and thus reducing variations in the sintering degree of the solid electrolyte layer.

[0057] In the present invention, the shape and / or structure of the particle binder of the cubic Li-La-Zr-Al composite oxide is confirmed by scanning electron microscopy (SEM). Furthermore, in the present invention, the BET diameter (D50) of the pulverized material in the pulverizability test is calculated from the BET specific surface area relative to the volume-based cumulative 50% particle diameter (D50) measured by laser diffraction scattering. ＢＥＴ ) ratio (D ＢＥＴ The larger the / D50 value, the wider the particle size distribution of the pulverized material and the more extremely fine particles are contained in the pulverized material. The aforementioned D50 value is calculated on a volume basis, so it is heavily influenced by larger particle sizes. On the other hand, D ＢＥＴ The value of D is greatly influenced by particles with small particle sizes. Therefore, the more extremely fine particles are included and the wider the particle size distribution, the higher D will be. ＢＥＴ The value of / D50 increases. Note that the BET diameter in this invention is the same as the "BET diameter (D)" in the embodiment described later. ＢＥＴ It can be calculated using the method described in the section ) ).

[0058] The cubic Li-La-Zr-Al composite oxide powder of the present invention is preferably used as a solid electrolyte in solid-state batteries and as a separator in solid-state batteries, and more preferably as a solid electrolyte in all-solid-state batteries and as a separator in all-solid-state batteries.

[0059] One way to use the cubic Li-La-Zr-Al composite oxide powder of the present invention is to use it as is, or after adjusting it to a desired particle size, disperse it in a solvent to form a slurry, and use it as a material for various applications. Another way to use the cubic Li-La-Zr-Al composite oxide powder of the present invention is to disperse it in a solvent, grind it with a media mill or the like to form a slurry, and use it as a material for various applications.

[0060] A preferred embodiment of the ceramic slurry of the present invention is a ceramic slurry comprising the cubic Li-La-Zr-Al composite oxide powder or pulverized thereof of the present invention and a solvent.

[0061] Furthermore, another preferred embodiment of the ceramic slurry of the present invention is one in which the content of the cubic Li-La-Zr-Al composite oxide component in the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component is 85% by mass or more, more preferably 90% by mass or more, and the D is calculated from the value of the BET specific surface area relative to the volume-based cumulative 50% particle diameter D50 measured by laser diffraction scattering. ＢＥＴ (However, the true density is 5.1 g / cm³) ３ The ratio (D) is calculated as follows: ＢＥＴ This is a ceramic slurry comprising cubic Li-La-Zr-Al composite oxide fine powder having a D50 ratio of 0.10 to 1.0, more preferably 0.20 to 1.0, more preferably 0.30 to 1.0, more preferably 0.40 to 1.0, more preferably 0.50 to 1.0, more preferably 0.50 to 0.90, and more preferably 0.50 to 0.80, and a solvent. The upper limit of the cubic Li-La-Zr-Al composite oxide component content can be 100% by mass or less.

[0062] The pulverized cubic Li-La-Zr-Al composite oxide powder of the present invention and the aforementioned cubic Li-La-Zr-Al composite oxide fine powder related to the ceramic slurry of the present invention may be any pulverized cubic Li-La-Zr-Al composite oxide powder of the present invention. As for the pulverization method, a pulverization method that can obtain pulverized material of a desired particle size can be appropriately selected.

[0063] Furthermore, the cubic Li-La-Zr-Al composite oxide powder of the present invention related to the ceramic slurry of the present invention, its pulverized product, and the aforementioned cubic Li-La-Zr-Al composite oxide fine powder have a ratio (Al / La) of the number of moles of Al on an atomic basis to the number of moles of La on an atomic basis, preferably 0.17 or more and 0.45 or less, preferably 0.17 or more and 0.40 or less, more preferably 0.25 or more and 0.40 or less, more preferably 0.28 or more and 0.35 or less, and particularly preferably 0.31 or more and 0.35 or less.

[0064] The solvent for the ceramic slurry of the present invention can be any solvent that can disperse the cubic Li-La-Zr-Al composite oxide powder or pulverized thereof of the present invention to prepare a slurry. Examples include ethanol, diacetone alcohol, isopropanol, butanol, pentanol, hexanol, cyclohexanone, acetone, N-methyl-2-pyrrolidone, acetonitrile, benzene, toluene, xylene, ethyl acetate, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, hexane, nonane, dodecane, methyl ethyl ketone, etc., and combinations thereof.

[0065] The ceramic slurry of the present invention may optionally contain resins (binders) such as polypropylene, polyvinyl butyral, acrylic, polyethyl methacrylate, polyvinylpyrrolidone, and combinations thereof.

[0066] The ceramic slurry of the present invention may optionally contain additives such as dispersants, defoamers, plasticizers, and rheology modifiers.

[0067] The content of the cubic Li-La-Zr-Al composite oxide of the present invention, its pulverized product, and the aforementioned cubic Li-La-Zr-Al composite oxide fine powder, as well as the slurry viscosity, etc., in the ceramic slurry of the present invention are appropriately selected depending on the method of use and application of the ceramic slurry.

[0068] As a method for producing the ceramic slurry of the present invention, a method for producing a ceramic slurry including a pulverization step of pulverizing the cubic Li-La-Zr-Al composite oxide powder of the present invention may be mentioned. The pulverization method in the pulverization step is not particularly limited as long as it is a pulverization method capable of obtaining a pulverized product having a desired particle size. Then, after carrying out the pulverization step, the obtained pulverized product of the cubic Li-La-Zr-Al composite oxide powder of the present invention, a solvent, and if necessary, the aforementioned additives, binder, etc. are mixed and kneaded to obtain the ceramic slurry of the present invention.

[0069] Further, as a method for producing the ceramic slurry of the present invention, a method for producing a ceramic slurry may be mentioned in which without pulverizing the cubic Li-La-Zr-Al composite oxide powder of the present invention, the powder is directly mixed with a solvent, and if necessary, the aforementioned additives, binder, etc., and kneaded to obtain the ceramic slurry of the present invention.

[0070] Further, as a method for producing the ceramic slurry of the present invention, a method for producing a ceramic slurry may be mentioned in which the cubic Li-La-Zr-Al composite oxide powder of the present invention is mixed with a solvent, and if necessary, the aforementioned additives, binder, etc., and pulverized by a media mill or the like to obtain the ceramic slurry of the present invention.

[0071] The method for producing the cubic Li-La-Zr-Al composite oxide powder according to the first aspect of the present invention comprises a Li element-containing raw material (M １ ), a La element-containing raw material (M ２ ), a Zr element-containing raw material (M ３ ) and an Al element-containing raw material (M ４ ) containing raw material composition (R Ａ ) a raw material composition preparation step (S Ａ１ ), and the raw material composition (R Ａ ) is heated to obtain a raw material composition heating step (S) for producing a cubic Li-La-Zr-Al composite oxide Ａ２ ), and the ratio of the number of moles of Al in atomic conversion to the number of moles of La in atomic conversion (Al / La) contained in the raw material composition (R Ａ ) is 0.17 or more and less than 0.50, and the raw material composition heating step (S Ａ２During the heating process of ), a precursor-containing composition (P) containing La-Li-Al composite oxide Ａ ) is produced, and the precursor-containing composition (P Ａ A method for producing cubic Li-La-Zr-Al composite oxide powder, characterized by generating a cubic Li-La-Zr-Al composite oxide by heating ).

[0072] A first embodiment of the present invention provides a method for producing cubic Li-La-Zr-Al composite oxide powder, comprising the raw material composition preparation step (S Ａ１ ) and the raw material composition heating process (S Ａ２ ) and have.

[0073] In a method for producing cubic Li-La-Zr-Al composite oxide powder according to the first embodiment of the present invention, the raw material composition preparation step (S Ａ１ ) is a Li element-containing raw material (M １ ), La element-containing raw material (M ２ ), Zr element-containing raw material (M ３ ) and Al element-containing raw materials (M ４ ) a raw material composition containing (R Ａ This is the process of preparing ).

[0074] Li element-containing raw material (M １ ) is a compound containing Li, and examples include inorganic or organic salts of Li, such as lithium hydroxide, lithium citrate, lithium peroxide, lithium acetate, lithium nitrate, lithium stearate, etc., of which lithium hydroxide is preferred.

[0075] Raw material containing La element (M ２ ) is a compound containing La, and examples include inorganic salts, organic salts, or oxides of La, such as lanthanum hydroxide, lanthanum nitrate, lanthanum carbonate, and lanthanum oxide, of which lanthanum hydroxide and lanthanum oxide are preferred.

[0076] Raw material containing Zr element (M ３ ) is a compound containing Zr, and examples include inorganic salts, organic salts, or oxides of Zr, such as zirconium hydroxide, zirconium nitrate, and zirconium oxide, of which zirconium hydroxide and zirconium oxide are preferred.

[0077] Raw material containing Al element (M ４ ) is a compound containing Al, and examples include inorganic salts, organic salts, oxides, nitrides, or carbides of Al, such as aluminum hydroxide, aluminum hydroxide oxide, aluminum nitrate, aluminum oxide, aluminum nitride, and tetraaluminum tricarbide. Of these, aluminum oxide, aluminum hydroxide, and aluminum hydroxide oxide are preferred, aluminum oxide and aluminum hydroxide are more preferred, and aluminum oxide is particularly preferred. Examples of aluminum oxide include α-alumina and γ-alumina.

[0078] Li element-containing raw material (M １ (i) Preferably, the Li-containing raw material has a reaction temperature of 600°C or less for an exothermic reaction accompanied by weight loss, or a reaction temperature of 600°C or less for an endothermic reaction accompanied by weight loss.

[0079] In case (i), the exothermic or endothermic reaction temperature or melting point associated with the weight loss of the Li-containing raw material is preferably 600°C or less, more preferably 150°C to 600°C, more preferably 200°C to 500°C, more preferably 300°C to 500°C, and more preferably 400°C to 500°C. In case (i), the exothermic or endothermic reaction temperature or melting point associated with the weight loss of the Li-containing raw material is within the above range, and the raw material composition (R ＡDuring the heating process, La-Li-Al composite oxide is more easily formed, increasing the reactivity of the raw material composition. Therefore, even when the raw material composition is heated at a lower temperature than conventional methods, or when heated at a high temperature for a short time, it is possible to easily produce a powder with a high content of cubic Li-La-Zr-Al composite oxide. In this invention, "reaction temperature for an exothermic reaction accompanied by weight loss or a reaction temperature for an endothermic reaction accompanied by weight loss" refers to a temperature within the range of 120°C to 600°C at a heating rate of 5°C / min when 10 mg of a sample is heated from 25°C to 650°C in an atmospheric environment, where the mass at 120°C is taken as 100% by mass, and an exothermic or endothermic reaction occurs. Furthermore, if there are multiple "temperatures at which weight loss occurs and an exothermic or endothermic reaction occurs," it is acceptable if any one of these temperatures is within a predetermined temperature range, while other "temperatures at which weight loss occurs and an exothermic or endothermic reaction occurs" exist outside that predetermined temperature range. For the aforementioned differential thermal and thermogravimetric simultaneous analysis, for example, the TG-DTA2000SA manufactured by Bruker can be used.

[0080] In case (i), Li-containing raw materials include lithium hydroxide, lithium citrate, lithium peroxide, lithium acetate, lithium nitrate, lithium stearate, etc., of which lithium hydroxide is preferred.

[0081] In case (i), the volume-based cumulative 50% particle size (D50) of the Li-containing raw material measured by laser diffraction scattering is preferably 300 μm or less, more preferably 250 μm or less, more preferably 200 μm or less, more preferably 150 μm or less, more preferably 100 μm or less, more preferably 50 μm or less, more preferably 25 μm or less, more preferably 10 μm or less, more preferably 5 μm or less, more preferably 1 μm or less, more preferably 0.5 μm or less, and more preferably 0.1 μm or less. In case (i), having the D50 of the Li-containing raw material within the above range enhances the effect of being able to produce a powder with a high content of cubic Li-La-Zr-Al composite oxide even when the raw material composition is heated at a lower temperature than conventional methods or when heated at a high temperature for a short time. The lower limit of the D50 of the Li-containing raw material is appropriately selected depending on the cost of grinding the raw material and the ease of manufacturing, but for example it can be 10 nm or more.

[0082] Raw material containing La element (M ２ (i) The La-containing raw material is preferably (i) a La-containing raw material whose reaction temperature for an exothermic reaction accompanied by weight loss or an endothermic reaction accompanied by weight loss or a melting point is 600°C or less, or (ii) a La-containing raw material that does not satisfy (i) and whose volume-based cumulative 50% particle size (D50) measured by laser diffraction scattering method is 9 μm or less.

[0083] In case (i), the exothermic or endothermic reaction temperature or melting point associated with the weight loss of the La element-containing raw material is preferably 600°C or less, more preferably 150°C to 600°C, more preferably 200°C to 500°C, and more preferably 300°C to 500°C. In case (i), the exothermic or endothermic reaction temperature or melting point associated with the weight loss of the La element-containing raw material is within the above range, and the raw material composition (R Ａ During the heating process, La-Li-Al composite oxide is more readily formed, increasing the reactivity of the raw material composition. Therefore, even when the raw material composition is heated at a lower temperature than conventional methods, or when heated at a high temperature for a short time, it is possible to easily produce a powder with a high content of cubic Li-La-Zr-Al composite oxide.

[0084] In case (i), examples of raw materials containing element La include lanthanum hydroxide, lanthanum nitrate, lanthanum carbonate, etc., of which lanthanum hydroxide is preferred.

[0085] In case (i), the D50 of the La element-containing raw material is preferably 20 μm or less, more preferably 15 μm or less, more preferably 10 μm or less, more preferably 5 μm or less, more preferably 1 μm or less, more preferably 0.5 μm or less, more preferably 0.3 μm or less, and more preferably 0.1 μm or less. In case (i), having the D50 of the La element-containing raw material within the above range enhances the effect that a powder with a high content of cubic Li-La-Zr-Al composite oxide can be produced even when the raw material composition is heated at a lower temperature than conventional methods or when it is heated at a high temperature for a short time. The lower limit of the D50 of the La element-containing raw material is appropriately selected depending on the cost of grinding the raw material and the ease of manufacturing, but for example it can be 10 nm or more.

[0086] In this invention, the volume-based cumulative 50% particle diameter (D50) measured by laser diffraction scattering refers to the particle diameter (median diameter) at which 50% of the volume-integrated particle size distribution is obtained when the object to be measured is measured by laser diffraction scattering. Specifically, it can be measured by the method described in the section "Measurement of volume-based cumulative 50% particle diameter (D50) measured by laser diffraction scattering" in the examples described below.

[0087] In case (i), the BET specific surface area of ​​the La element-containing raw material is preferably 0.1 m². ２ / g or more, more preferably 0.5m ２ / g or more, more preferably 1m ２ / g or more, more preferably 5m ２ / g or more, more preferably 10m ２ / g or more, more preferably 50m ２ / g or more, more preferably 100m ２It is 1000 m² or more. In case (i), if the BET specific surface area of ​​the La element-containing raw material is within the above range, the effect of being able to produce a powder with a high content of cubic Li-La-Zr-Al composite oxide is enhanced, even when the raw material composition is heated at a lower temperature than conventional methods or when it is heated at a high temperature for a short time. The upper limit of the BET specific surface area of ​​the La element-containing raw material is appropriately selected depending on the cost of raw material production and ease of production, for example, 1000 m² ２ It can be less than or equal to / g.

[0088] In the case of (ii), the La-containing raw material does not satisfy (i). Furthermore, the D50 of the La-containing raw material in the case of (ii) is preferably 9 μm or less, more preferably 8 μm or less, more preferably 6 μm or less, more preferably 4 μm or less, more preferably 2 μm or less, more preferably 1 μm or less, more preferably 0.5 μm or less, and more preferably 0.1 μm or less. Because the D50 of the La-containing raw material in the case of (ii) is within the above range, the raw material composition (R Ａ During the heating process, La-Li-Al composite oxide is more readily formed, increasing the reactivity of the raw material composition. Therefore, even when the raw material composition is heated at a lower temperature than conventional methods, or when heated at a high temperature for a short time, it is possible to easily produce a powder with a high content of cubic Li-La-Zr-Al composite oxide. The lower limit of D50 for the La element-containing raw material is appropriately selected based on factors such as the cost of grinding the raw material and ease of manufacturing, but can be, for example, 10 nm or more.

[0089] In the case of (ii), examples of raw materials containing element La include lanthanum oxide, and among these, lanthanum oxide is preferred.

[0090] In case (ii), the BET specific surface area of ​​the La element-containing raw material is preferably 1 m². ２ / g or more, more preferably 3m ２ / g or more, more preferably 5m ２ / g or more, more preferably 10m ２ / g or more, more preferably 50m ２ / g or more, more preferably 100m ２It is 1000 m² or more. In the case of (ii), if the BET specific surface area of ​​the La element-containing raw material is within the above range, the effect of being able to produce a powder with a high content of cubic Li-La-Zr-Al composite oxide is enhanced, even when the raw material composition is heated at a lower temperature than conventional methods or when it is heated at a high temperature for a short time. The upper limit of the BET specific surface area of ​​the La element-containing raw material is appropriately selected depending on the cost of raw material production and ease of production, for example, 1000 m². ２ It can be less than or equal to / g.

[0091] Raw material containing Zr element (M ３ (i) The Zr-containing raw material is preferably (i) a Zr-containing raw material whose reaction temperature for an exothermic reaction accompanied by weight loss or an endothermic reaction accompanied by weight loss or a melting point is 600°C or less, or (ii) a Zr-containing raw material that does not satisfy (i) and whose volume-based cumulative 50% particle size (D50) measured by laser diffraction scattering method is 5 μm or less.

[0092] In case (i), the exothermic or endothermic reaction temperature or melting point associated with the weight loss of the Zr-containing raw material is 600°C or less, preferably 150°C to 500°C, and more preferably 200°C to 400°C. Because the exothermic or endothermic reaction temperature or melting point associated with the weight loss of the Zr-containing raw material in case (i) is within the above range, the reactivity of the Zr-containing raw material is increased, making it easier to produce a powder with a high content of cubic Li-La-Zr-Al composite oxide, even when the reaction raw material composition is heated at a lower temperature than conventional methods or when it is heated at a high temperature for a short time.

[0093] In case (i), Zr element-containing raw materials include zirconium hydroxide and zirconium nitrate, of which zirconium hydroxide is preferred.

[0094] In case (i), the D50 of the Zr-containing raw material is preferably 20 μm or less, more preferably 15 μm or less, more preferably 10 μm or less, more preferably 5 μm or less, more preferably 1 μm or less, more preferably 0.5 μm or less, and more preferably 0.1 μm or less. In case (i), having the D50 of the Zr-containing raw material within the above range enhances the effect that a powder with a high content of cubic Li-La-Zr-Al composite oxide can be produced even when the raw material composition is heated at a lower temperature than conventional methods or when it is heated at a high temperature for a short time. The lower limit of the D50 of the Zr-containing raw material is appropriately selected depending on the cost of grinding the raw material and the ease of manufacturing, but for example it can be 10 nm or more.

[0095] In case (ii), the Zr-containing raw material does not satisfy (i). In case (ii), the D50 of the Zr-containing raw material is preferably 5 μm or less, more preferably 4 μm or less, more preferably 3 μm or less, more preferably 2 μm or less, more preferably 1 μm or less, more preferably 0.5 μm or less, and more preferably 0.1 μm or less. Because the D50 of the Zr-containing raw material in case (ii) is within the above range, the reactivity of the Zr-containing raw material is increased, making it easier to produce a powder with a high content of cubic Li-La-Zr-Al composite oxide, even when the raw material composition is heated at a lower temperature than conventional methods or when heated at a high temperature for a short time. The lower limit of the D50 of the Zr-containing raw material is appropriately selected depending on the cost of grinding the raw material and the ease of manufacturing, but for example, it can be 10 nm or more.

[0096] In the case of (ii), examples of Zr element-containing raw materials include zirconium oxide, and among these, zirconium oxide is preferred.

[0097] In case (ii), the BET specific surface area of ​​the Zr element-containing raw material is preferably 10 m². ２ / g or more, more preferably 15m ２ / g or more, more preferably 20m ２ / g or more, more preferably 30m ２ / g or more, more preferably 50m ２ / g or more, more preferably 100m ２ It is 1000 m² or more. In case (ii), if the BET specific surface area of ​​the Zr element-containing raw material is within the above range, the effect of being able to produce a powder with a high content of cubic Li-La-Zr-Al composite oxide is enhanced, even when the raw material composition is heated at a lower temperature than conventional methods or when it is heated at a high temperature for a short time. The upper limit of the BET specific surface area of ​​the Zr element-containing raw material is appropriately selected depending on the cost and ease of manufacturing the raw material, for example, 1000 m². ２ It can be less than or equal to / g.

[0098] Raw material containing Al element (M ４ ) is an Al-containing raw material whose reaction temperature for an exothermic reaction accompanied by weight loss or an endothermic reaction accompanied by weight loss or a melting point is 600°C or less, or (ii) an Al-containing raw material that does not satisfy (i) and whose volume-based cumulative 50% particle size (D50) measured by laser diffraction scattering method is 9 μm or less.

[0099] In case (i), the exothermic or endothermic reaction temperature or melting point associated with the weight loss of the Al-containing raw material is preferably 600°C or less, more preferably 150°C to 500°C, more preferably 200°C to 500°C, more preferably 250°C to 500°C, and more preferably 300°C to 500°C. In case (i), the exothermic or endothermic reaction temperature or melting point associated with the weight loss of the Al-containing raw material is within the above range, and the raw material composition (R Ａ During the heating process, La-Li-Al composite oxide is more readily formed, which increases the reactivity of the reaction raw material composition. Therefore, even when the raw material composition is heated at a lower temperature than conventional methods, or when it is heated at a high temperature for a short time, a powder with a high content of cubic Li-La-Zr-Al composite oxide can be produced.

[0100] In case (i), Al-containing raw materials include aluminum hydroxide, aluminum hydroxide oxide, aluminum nitrate, etc., of which aluminum hydroxide and aluminum hydroxide oxide are preferred, and aluminum hydroxide is particularly preferred.

[0101] In case (i), the D50 of the Al-containing raw material is preferably 20 μm or less, more preferably 15 μm or less, more preferably 10 μm or less, more preferably 5 μm or less, more preferably 1 μm or less, more preferably 0.5 μm or less, and more preferably 0.1 μm or less. In case (i), having the D50 of the Al-containing raw material within the above range enhances the effect that a powder with a high content of cubic Li-La-Zr-Al composite oxide can be produced even when the raw material composition is heated at a lower temperature than conventional methods or when it is heated at a high temperature for a short time. The lower limit of the D50 of the Al-containing raw material is appropriately selected depending on the cost of grinding the raw material and the ease of manufacturing, but for example it can be 10 nm or more.

[0102] In case (ii), the Al-containing raw material does not satisfy (i). Furthermore, the D50 of the Al-containing raw material in case (ii) by laser diffraction scattering is 9 μm or less, preferably 8 μm or less, more preferably 6 μm or less, more preferably 4 μm or less, more preferably 2 μm or less, more preferably 1 μm or less, more preferably 0.5 μm or less, and more preferably 0.1 μm or less. Because the D50 of the Al-containing raw material in case (ii) is within the above range, the raw material composition (R Ａ During the heating process, La-Li-Al composite oxide is more readily formed, increasing the reactivity of the raw material composition. Therefore, even when the raw material composition is heated at a lower temperature than conventional methods, or when heated at a high temperature for a short time, it is possible to easily produce a powder with a high content of cubic Li-La-Zr-Al composite oxide. The lower limit of D50 of the Al element-containing raw material is appropriately selected based on factors such as the cost of grinding the raw material and ease of manufacturing, but can be set to, for example, 10 nm or higher.

[0103] Examples of Al-containing raw materials in case (ii) include aluminum oxide, aluminum nitride, tetraaluminum tricarbide, etc., of which aluminum oxide is preferred. Examples of aluminum oxide include α-alumina and γ-alumina.

[0104] In case (ii), the BET specific surface area of ​​the Al-containing raw material is preferably 1.0 m². ２ / g or more, more preferably 1.2m ２ / g or more, more preferably 1.4m ２ / g or more, more preferably 1.6m ２ / g or more, more preferably 1.8m ２ / g or more, more preferably 2.0m ２ / g or more, more preferably 3.0m ２ / g or more, more preferably 4.0m ２ / g or more, more preferably 5.0m ２ / g or more, more preferably 10m ２ / g or more, more preferably 50m ２ / g or more, more preferably 100m ２ It is 1000 m² or more. In case (ii), if the BET specific surface area of ​​the Al element-containing raw material is within the above range, the effect of being able to produce a powder with a high content of cubic Li-La-Zr-Al composite oxide is enhanced, even when the raw material composition is heated at a lower temperature than conventional methods or when it is heated at a high temperature for a short time. The upper limit of the BET specific surface area of ​​the Al element-containing raw material is appropriately selected depending on the cost of raw material production and ease of production, for example, 1000 m² ２ It can be less than or equal to / g.

[0105] Raw material composition preparation process (S Ａ１ ) is a Li element-containing raw material (M １ ), La element-containing raw material (M ２ ), Zr element-containing raw material (M ３ ) and Al element-containing raw materials (M ４ ) a raw material composition containing (R Ａ This is the process of preparing ).

[0106] Raw material composition preparation process (S Ａ１ In the raw material composition (R Ａ The method for preparing the Li element-containing raw material (M) is not particularly limited, and １ ), La element-containing raw material (M ２ ), Zr element-containing raw material (M ３ ) and Al element-containing raw materials (M ４ ) a raw material composition containing (R ＡAny method that can prepare (M) is acceptable. More specifically, for example, a Li-containing raw material (M) in powder form, suspension form dispersed in a dispersion solvent, or solution form dissolved in a solution. １ ), La element-containing raw material (M ２ ), Zr element-containing raw material (M ３ ) and Al element-containing raw materials (M ４ One method involves mixing the ingredients and stirring them using a mortar and pestle, propeller mixer, rotary mixer, rocking mixer, V-blender, etc. When using suspension or solution-type raw materials dispersed in a dispersion, the resulting mixture may be dried after mixing and stirring to remove the dispersion medium or solvent. Alternatively, the aforementioned raw materials may be mixed while being ground using a jet mill, ball mill, bead mill, etc. They may also be ground, mixed, and / or ground while being heated using a heated mixing and stirring machine, etc. All of the aforementioned raw materials may be mixed or processed simultaneously, or two or three types may be mixed first, and then other raw materials may be added or mixed.

[0107] In the first embodiment of the present invention and the second embodiment described below, the raw material composition (R Ａ The ratio of the number of moles of Al (on an atomic basis) to the number of moles of La (on an atomic basis) contained in the raw material composition (R) is 0.17 or more and less than 0.50, preferably 0.20 or more and 0.45 or less, more preferably 0.25 or more and 0.40 or less, more preferably 0.28 or more and 0.35 or less, and more preferably 0.31 or more and 0.35 or less. Ａ The ratio of the number of moles of Al (Al / La) to the number of moles of La (La) contained in the raw material composition (R) is within the above range. Ａ During the heating process, La-Li-Al composite oxides are more readily formed, increasing the reactivity of the raw material composition. Therefore, even when the raw material composition is heated at a lower temperature than conventional methods, or when heated at a high temperature for a short time, a powder with a high content of cubic Li-La-Zr-Al composite oxides can be produced.

[0108] In a method for producing cubic Li-La-Zr-Al composite oxide powder according to the first embodiment of the present invention, the raw material composition heating step (S Ａ２ ) is a raw material composition (RＡ This is a step in which the raw material composition heating step (S Ａ２ ) In the raw material composition heating process (S Ａ２ During the heating of the raw material composition (R Ａ ) Li element-containing raw material (M １ ), La element-containing raw material (M ２ ) and Al element-containing raw materials (M ４ ) reacts to form a La-Li-Al composite oxide, so in the heating process, the precursor-containing composition (P) containing the La-Li-Al composite oxide reacts Ａ ) is generated. Then, the raw material composition heating step (S Ａ２ ) contains a precursor-containing composition (P) that contains La-Li-Al composite oxide generated during the heating process. Ａ By further heating the mixture, a cubic Li-La-Zr-Al composite oxide is produced.

[0109] In addition, in the present invention, a precursor-containing composition (P) containing a La-Li-Al composite oxide is used. Ａ Regarding the generation of the precursor containing La-Li-Al composite oxide (P), the raw material composition is heated to 700°C at a rate of 5°C / min in an atmospheric environment, kept at 700°C for 3 hours, and then cooled at a rate of 2°C / min. When the 700°C heated powder obtained is measured using the method described in "Measurement of the content of each component in the 700°C heated powder" below, if the La-Li-Al composite oxide is generated at a rate of 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, more preferably 4% by mass or more, more preferably 5% by mass or more, and more preferably 6% by mass or more, then the precursor containing La-Li-Al composite oxide (P) is defined as the precursor containing La-Li-Al composite oxide. Ａ) is assumed to have been generated. Furthermore, when the aforementioned 700°C heated powder is measured by the method described in "Measurement of the content of each component in the 700°C heated powder" below, the La-Li-Al composite oxide is preferably 35% by mass or less, more preferably 30% by mass or less, and particularly preferably 25% by mass or less. This makes it easier to increase the content of the cubic Li-La-Zr-Al composite oxide component in the cubic Li-La-Zr-Al composite oxide powder of the present invention, and also improves the pulverability, making it easier to pulverize to an appropriate size and making it difficult to generate extremely fine particles during pulverization.

[0110] A raw material composition heating step (S) according to the first embodiment and the second embodiment described later of the present invention. Ａ２ The heating temperature range, maximum temperature reached, and holding temperature in ) are determined by the raw material composition (R Ａ The heating temperature range, maximum temperature reached, and holding temperature should be such that cubic Li-La-Zr-Al composite oxide is formed by heating of the material.

[0111] A raw material composition heating step (S) according to the first embodiment and the second embodiment described later of the present invention. Ａ２ For example, the raw material composition (R Ａ The raw material composition is heated to a maximum temperature of 700°C or higher but less than 1300°C. Ａ２ In the raw material composition (R Ａ When heating to a maximum temperature of 700°C or higher but less than 1300°C, the heating time is preferably 1 hour or more and 24 hours or less, more preferably 2 hours or more and 15 hours or less. Furthermore, the time during which the heating temperature is in the range of the maximum temperature is preferably 80% or more, more preferably 90% or more, and more preferably 95% or more, compared to the time during which the temperature is in the range of 700°C or higher.

[0112] In this invention, the highest temperature reached when heating the object to be heated refers to the highest temperature reached during the period from the start to the end of heating the object. Also, in this invention, the heating time when heating the object to be heated at a maximum temperature of X°C or higher but less than or equal to Y°C refers to the time during which the heating temperature is within the temperature range of X°C or higher but less than or equal to Y°C.

[0113] A raw material composition heating step (S) according to the first embodiment and the second embodiment described later of the present invention. Ａ２ For example, the raw material composition (R) can be prepared at a lower temperature than conventional methods. Ａ ) can be heated. When the purpose is to heat at a lower temperature than conventional methods, the raw material composition (R Ａ The maximum temperature reached when heating the raw material composition (S) is 700°C or more and less than 1000°C, preferably 800°C or more and 950°C or less. Furthermore, the time spent in the temperature range where the heating temperature is in the maximum temperature range is preferably 80% or more, more preferably 90% or more, and more preferably 95% or more, compared to the time spent in the temperature range of 700°C or more. Raw material composition heating step (S Ａ２ ) raw material composition (R Ａ By setting the maximum temperature reached when heating the material within the above range, it is possible to produce a powder with a higher content of cubic Li-La-Zr-Al composite oxide at a lower temperature than conventional methods. The heating rate can be appropriately selected, but for example, it can be 1°C / min to 500°C / min, 2°C / min to 400°C / min, or 3°C / min to 300°C / min.

[0114] A raw material composition heating step (S) according to the first embodiment and the second embodiment described later of the present invention. Ａ２ For example, the raw material composition (R) is prepared at a high temperature and short time similar to that of conventional methods. Ａ When the purpose is to heat the raw material composition (R Ａ The maximum temperature reached when heating the raw material composition (S) is preferably 900°C or more and less than 1300°C, preferably 900°C or more and 1250°C or less, more preferably 900°C or more and 1200°C or less, more preferably 900°C or more and 1150°C or less, and more preferably 900°C or more and 1100°C or less, and the heating time is preferably 1 hour or more and 24 hours or less. Raw material composition heating step (S Ａ２ ) raw material composition (R ＡBy setting the maximum temperature reached and heating time during heating within the above range, a powder with a high content of cubic Li-La-Zr-Al composite oxide can be produced at a temperature and in a short time comparable to conventional methods. Preferably, the time spent in the temperature range where the heating temperature is in the maximum temperature range is 80% or more, more preferably 90% or more, and more preferably 95% or more, relative to the time spent in the temperature range of 900°C or higher. The heating rate can be appropriately selected, for example, 1°C / min to 500°C / min, 2°C / min to 400°C / min, or 3°C / min to 300°C / min.

[0115] A raw material composition heating step (S) according to the first embodiment and the second embodiment described later of the present invention. Ａ２ ) First, the raw material composition (R Ａ By heating the mixture, preferably at a temperature of 400°C to 900°C, the precursor-containing composition (P) containing La-Li-Al composite oxide is heated during the heating process. Ａ ) is produced, and this precursor-containing composition (P Ａ By further heating the mixture to a predetermined maximum temperature, for example, between 700°C and 1300°C, a cubic Li-La-Zr-Al composite oxide powder can be obtained.

[0116] A raw material composition heating step (S) according to the first embodiment and the second embodiment described later of the present invention. Ａ２ ) In the raw material composition (R Ａ ) is heated to produce a precursor-containing composition (P) containing La-Li-Al composite oxide. Ａ ) is obtained, and then the precursor-containing composition (P Ａ By heating the raw material composition, the raw material composition heating process (S Ａ２ ) can be performed.

[0117] A raw material composition heating step (S) according to the first embodiment and the second embodiment described later of the present invention. Ａ２ In the raw material composition (R Ａ The atmosphere when heating the gas may be an oxidizing atmosphere such as oxygen gas or air, or a non-oxidizing atmosphere such as nitrogen gas, helium gas, or argon gas.

[0118] A raw material composition heating step (S) according to the first embodiment and the second embodiment described later of the present invention. Ａ２ ) In the powdered raw material composition (R Ａ The raw material composition (R) may be heated, or the powdered raw material composition (R) may be heated. Ａ After calcining at 500-900°C, the raw material is pelletized to form a pelletized raw material composition (R Ａ The raw material composition (R) may be heated. In order to obtain cubic Li-La-Zr-Al composite oxide powder, the powdered raw material composition (R) may be heated, from the viewpoint of cost, etc. Ａ It is preferable to obtain a powdered cubic Li-La-Zr-Al composite oxide by heating the mixture.

[0119] In the first embodiment of the present invention and the second embodiment described later, the method for producing cubic Li-La-Zr-Al composite oxide powder is as follows: raw material composition heating step (S Ａ２ After performing the above steps, the resulting cubic Li-La-Zr-Al composite oxide powder or pellets can be crushed and / or classified as needed.

[0120] Adding Al to Li-La-Zr composite oxide facilitates the formation of cubic Li-La-Zr-Al composite oxide. Conventionally, however, a raw material composition containing Li-containing raw materials, La-containing raw materials, and Zr-containing raw materials was first heated to produce Li-La-Zr composite oxide, and then Al-containing raw materials were added to the obtained composite oxide and heated to obtain cubic Li-La-Zr-Al composite oxide. In contrast, in the first embodiment of the present invention, a method for producing cubic Li-La-Zr-Al composite oxide powder, an Al-containing raw material is present in the raw material composition along with a Li-containing raw material and a La-containing raw material, and when the raw material composition is heated, La-Li-Al composite oxide is formed at a heating temperature of approximately 600°C to 800°C during the heating process. This La-Li-Al composite oxide becomes a precursor of cubic Li-La-Zr-Al composite oxide and has high reactivity with other raw materials present in the reaction raw material composition, making it easier to produce cubic Li-La-Zr-Al composite oxide than in conventional methods. As a result, in the first embodiment of the present invention, a method for producing cubic Li-La-Zr-Al composite oxide powder, the raw material composition (R ＡEven when heated at a lower temperature than conventional methods, or when heated at a high temperature for a short time, a powder with a high content of cubic Li-La-Zr-Al composite oxide can be produced.

[0121] A second embodiment of the present invention provides a method for producing cubic Li-La-Zr-Al composite oxide powder, using a Li-containing raw material (M １ ), La element-containing raw material (M ２ ), Zr element-containing raw material (M ３ ) and Al element-containing raw materials (M ４ ) a raw material composition containing (R Ａ ) Raw material composition preparation step (S Ａ１ ) and the raw material composition (R Ａ A raw material composition heating step (S) is performed to heat the raw material to generate a cubic Li-La-Zr-Al composite oxide. Ａ２ ) and the raw material composition (R Ａ The ratio of the number of moles of Al (on an atomic basis) to the number of moles of La (on an atomic basis) contained in the Li element raw material (M １ (i) The La element-containing raw material (M ２ (i) The exothermic or endothermic reaction temperature or melting point accompanied by weight loss is 600°C or less, or (ii) The (i) is not satisfied and the volume-based cumulative 50% particle size (D50) measured by laser diffraction scattering is 9 μm or less, The Zr element-containing raw material (M ３ (i) The exothermic or endothermic reaction temperature or melting point accompanied by weight loss is 600°C or less, or (ii) The (i) is not satisfied and the volume-based cumulative 50% particle size (D50) measured by laser diffraction scattering is 5 μm or less, The Al element-containing raw material (M ４ The method for producing cubic Li-La-Zr-Al composite oxide powder is characterized by the following: (i) the exothermic or endothermic reaction temperature accompanied by weight loss or the melting point is 600°C or less, or (ii) the condition (i) is not met and the volume-based cumulative 50% particle size (D50) by laser diffraction scattering method is 9 μm or less.

[0122] A Li-containing raw material (M) related to a method for producing cubic Li-La-Zr-Al composite oxide powder according to a second embodiment of the present invention. １ ), La element-containing raw material (M ２ ), Zr element-containing raw material (M ３ ) and Al element-containing raw materials (M ４ ) is a Li-containing raw material (M) related to the method for producing cubic Li-La-Zr-Al composite oxide powder according to the first embodiment of the present invention. １ ) is a Li-containing raw material in case (i) of the above, and a La-containing raw material (M ２ ) either (i) a La-containing raw material, or (ii) a La-containing raw material, and a Zr-containing raw material (M ３ ) is either a Zr-containing raw material in case (i) or a Zr-containing raw material in case (ii), and an Al-containing raw material (M ４ The Al-containing raw material in case (i) of the above, or the Al-containing raw material in case (ii).

[0123] The raw material composition preparation step (S) relating to the method for producing cubic Li-La-Zr-Al composite oxide powder according to the second embodiment of the present invention. Ａ１ ) is the Li element-containing raw material in the case of (i) (M １ ), (i) or (ii) La element-containing raw materials (M ２ ), (i) or (ii) Zr element-containing raw materials (M ３ ) and in the case of (i) or (ii), the Al-containing raw material (M ４ ) a raw material composition containing (R Ａ This is the process of preparing ).

[0124] Raw material composition preparation process (S Ａ１ In the raw material composition (R Ａ The method for preparing (i) is not particularly limited, and the Li element-containing raw material (M １ ), (i) or (ii) La element-containing raw materials (M ２ ), (i) or (ii) Zr element-containing raw materials (M ３ ) and in the case of (i) or (ii), the Al-containing raw material (M ４ ) a raw material composition containing (RＡ Any method that can prepare the raw material composition preparation step (S) of the first embodiment of the present invention is acceptable. More specifically, for example, Ａ１ As a concrete example, the same method as described above may be used.

[0125] In a method for producing cubic Li-La-Zr-Al composite oxide powder according to a second embodiment of the present invention, the raw material composition heating step (S Ａ２ ) is a raw material composition (R Ａ This is a process of heating ) to produce a cubic Li-La-Zr-Al composite oxide.

[0126] In a method for producing cubic Li-La-Zr-Al composite oxide powder according to a second embodiment of the present invention, the raw material composition heating step (S Ａ２ ) In the raw material composition heating process (S Ａ２ During the heating of the raw material composition (R Ａ ) Li element-containing raw material (M １ ), La element-containing raw material (M ２ ) and Al element-containing raw materials (M ４ ) react to form a La-Li-Al composite oxide, but Li element-containing raw material (M １ ), La element-containing raw material (M ２ ) and Al element-containing raw materials (M ４ Since the ) has predetermined physical properties, that is, it has the physical properties of (i) or (ii), the amount of La-Li-Al composite oxide produced increases during the heating process. For this reason, the method for producing cubic Li-La-Zr-Al composite oxide powder in the second embodiment of the present invention is a raw material composition heating step (S Ａ２ A precursor-containing composition (P) containing La-Li-Al composite oxide generated during the heating process of ) Ａ The reactivity of ) increases, resulting in a higher content of cubic Li-La-Zr-Al composite oxide in the product.

[0127] A third embodiment of the present invention provides a method for producing cubic Li-La-Zr-Al composite oxide powder, comprising: La-Li-Al composite oxide, Li element-containing raw material (M １ ), Zr element-containing raw material (M ３ ) and Al element-containing raw materials (M ４ ) precursor-containing composition (PＢ A precursor-containing composition preparation step (S Ｂ１ ) and the precursor-containing composition (P Ｂ A precursor-containing composition heating step (S) is performed to heat the mixture to generate a cubic Li-La-Zr-Al composite oxide. Ｂ２ ) and the precursor-containing composition (P Ｂ The method for producing cubic Li-La-Zr-Al composite oxide powder is characterized in that the ratio of the number of moles of Al (on an atomic basis) to the number of moles of La (on an atomic basis) contained in the powder (Al / La) is 0.17 or more and less than 0.50.

[0128] The method for producing the precursor-containing composition containing the La-Li-Al composite oxide of the present invention is to use a Li element-containing raw material (M １ ), La element-containing raw material (M ２ ) and Al element-containing raw materials (M ４ A precursor raw material composition containing (R Ｃ Precursor raw material composition preparation step (S Ｃ１ ) and the precursor raw material composition (R Ｃ ) is heated to form a precursor-containing composition (P) containing La-Li-Al composite oxide. Ｃ１ Heating step (S) for the precursor raw material composition to obtain Ｃ２ ) and the precursor raw material composition (R Ｃ The present invention relates to a method for producing a precursor-containing composition containing a La-Li-Al composite oxide, characterized in that the ratio of the number of moles of Al (on an atomic basis) to the number of moles of La (on an atomic basis) contained in the composition (Al / La) is 0.17 or more and less than 0.50.

[0129] A fourth embodiment of the present invention provides a method for producing cubic Li-La-Zr-Al composite oxide powder, which involves producing a precursor-containing composition containing the La-Li-Al composite oxide according to the present invention, and obtaining a precursor-containing composition (P Ｃ１ ) and Zr element-containing raw materials (M ３ ) precursor-containing composition (P Ｃ２ A precursor-containing composition preparation step (S Ｃ３ ) and precursor-containing composition (P Ｃ２A precursor-containing composition heating step (S) is performed to heat the mixture to generate a cubic Li-La-Zr-Al composite oxide. Ｃ４ ) and have.

[0130] The cubic Li-La-Zr-Al composite oxide obtained by producing the cubic Li-La-Zr-Al composite oxide powder according to the first, second, third, and fourth embodiments of the present invention is a composite oxide having a garnet-type crystal structure.

[0131] The cubic Li-La-Zr-Al composite oxide obtained by producing cubic Li-La-Zr-Al composite oxide powder according to the first, second, third, and fourth embodiments of the present invention is a cubic composite oxide.

[0132] In the first, second, third, and fourth embodiments of the present invention, the methods for producing cubic Li-La-Zr-Al composite oxide powder are preferably selected in terms of the amounts of Li-containing raw materials, La-containing raw materials, Zr-containing raw materials, and Al-containing raw materials used so that the composition of the cubic Li-La-Zr-Al composite oxide in the resulting cubic Li-La-Zr-Al composite oxide powder is that of the cubic Li-La-Zr-Al composite oxide represented by general formula (2).

[0133] In the methods for producing cubic Li-La-Zr-Al composite oxide powder according to the first, second, third, and fourth embodiments of the present invention, the stoichiometric composition of the La-Li-Al composite oxide in the method for producing a precursor-containing composition containing the La-Li-Al composite oxide of the present invention is preferably the La-Li-Al composite oxide represented by the above formula (4).

[0134] In the method for producing a precursor-containing composition containing La-Li-Al composite oxide of the present invention, it is preferable to select the amounts of Li-containing raw materials, La-containing raw materials, and Al-containing raw materials used so that the composition of the La-Li-Al composite oxide is represented by general formula (4).

[0135] In this invention, the presence of cubic Li-La-Zr-Al composite oxide in the product, the content of cubic Li-La-Zr-Al composite oxide in the product, the presence of tetragonal Li-La-Zr composite oxide in the product, and the content of tetragonal Li-La-Zr composite oxide in the product are determined by X-ray diffraction.

[0136] Furthermore, the configurations, methods, procedures, and processes described herein are illustrative and do not limit the present invention; numerous variations are applicable within the scope of the present invention.

[0137] The present invention will be described below based on specific experimental examples, but the present invention is not limited to these.

[0138] (Experimental Example 1) First, a raw material composition was prepared by mixing the powdered Li-containing raw material, powdered La-containing raw material, and powdered Zr-containing raw material listed in Table 1. At this time, the ratio of the number of Li, La, and Zr atoms in the raw material composition was set to 7:3:2. Next, the obtained raw material composition was heated to 900°C at a heating rate of 10°C / min in an air atmosphere and at 1 atmosphere, held at 900°C for 6 hours, and then cooled at 2°C / min. The obtained powder was pulverized using a vibratory mill, and γ-alumina listed in Table 1 was mixed in with the ratio of Al atoms to La listed in Table 1, and pelletized by press molding. These pellets were heated to 1000°C at a heating rate of 3.3°C / min in an air atmosphere and at 1 atmosphere, held at 1000°C for 36 hours, and then cooled at 2°C / min. After that, the obtained pellets were pulverized to obtain the product powder. Next, the content of cubic Li-La-Zr-Al composite oxide, tetragonal Li-La-Zr composite oxide, La-Li-Al composite oxide, lanthanum aluminate, lithium zirconate, lithium aluminate, and lanthanum zirconate was measured in the obtained product powder using the method described in "Measurement of the content of each component in the product powder" below. The results are shown in Table 1.

[0139] (Experimental Examples 2-35) First, a raw material composition was prepared by mixing the powdered Li-containing raw material, powdered La-containing raw material, powdered Zr-containing raw material, and powdered Al-containing raw material listed in Tables 1-7. At this time, the ratio of the number of Li, La, and Zr atoms in the raw material composition was set to 7:3:2. The ratio of the number of Al atoms to La atoms in the raw material composition was as shown in Tables 1-7. Next, the obtained raw material composition was heated in an air atmosphere at 1 atmosphere at a heating rate of 5°C / min, and held for the maximum temperature reached and the holding time at that maximum temperature listed in Tables 1-7, respectively, and then cooled at 2°C / min to obtain the product powder. Next, the content of cubic Li-La-Zr-Al composite oxide, tetragonal Li-La-Zr composite oxide, La-Li-Al composite oxide, lanthanum aluminate, lithium zirconate, lithium aluminate, and lanthanum zirconate was measured in the obtained product powder using the method described in "Measurement of the content of each component in the product powder" below. The results are shown in Tables 1 to 7.

[0140] <Measurement of the content of each component in the product powder> Using an XRD measuring device (SmartLab, manufactured by Rigaku Corporation), CuKα rays (wavelength λ: 1.5418 Å) were used, and XRD measurements were performed for diffraction angles 2θ: 15° to 80° under the conditions of tube voltage 40kV, tube current 25mA, step angle 0.0152°, and scanning speed 10° / min. Next, using Rigaku's integrated powder X-ray analysis software PDXL as the analysis software, cubic Li-La-Zr-Al composite oxide, tetragonal Li-La-Zr composite oxide, La-Li-Al composite oxide, lanthanum aluminate, lithium zirconate, lithium aluminate, and lanthanum zirconate were selected as the target components, and the mass ratio of each component to the total of the above-mentioned target components was calculated from the integrated intensity of the strongest diffraction peak of each component using the RIR method.

[0141] Furthermore, the raw material compositions obtained in the same manner as in Experimental Examples 2 to 8 described in Table 1 or 2 and Experimental Examples 33 to 35 described in Table 7 were heated in an air atmosphere at 1 atmosphere at a heating rate of 5°C / min to a maximum temperature of 700°C, held at that maximum temperature for 3 hours, and then cooled at 2°C / min to obtain 700°C heated powder. Next, the content of La-Li-Al composite oxide, cubic Li-La-Zr-Al composite oxide, lanthanum zirconate, and lanthanum oxide was measured in the obtained 700°C heated powder using the method described in "Measurement of the content of each component in 700°C heated powder" below. The results are shown in Tables 1 to 7. In the tables, the column "700°C × 3h heating" shows the analysis results of 700°C heated powder held at a maximum temperature of 700°C for 3 hours. Furthermore, since Experimental Examples 9, 15, 21, and 27 used the same raw material composition as Experimental Example 3, Experimental Examples 10, 16, 22, and 28 used the same composition as Experimental Example 4, Experimental Examples 11, 17, 23, and 29 used the same composition as Experimental Example 5, Experimental Examples 12, 18, 24, and 30 used the same composition as Experimental Example 6, Experimental Examples 13, 19, 25, and 31 used the same composition as Experimental Example 7, and Experimental Examples 14, 20, 26, and 32 used the same composition as Experimental Example 8, the results of Experimental Examples 3 to 8 are also shown in the section for the analysis results of 700°C heated powder in the Experimental Examples using the same composition as the raw material composition.

[0142] <Measurement of the content of each component in powder heated to 700°C> Using an XRD measuring device (SmartLab, manufactured by Rigaku Corporation), CuKα rays (wavelength λ: 1.5418 Å) were used, and XRD measurements were performed for diffraction angles 2θ: 15° to 80° under the conditions of tube voltage 40kV, tube current 25mA, step angle 0.0152°, and scanning speed 10° / min. Next, using the Rigaku Integrated Powder X-ray Analysis Software PDXL as the analysis software, cubic Li-La-Zr-Al composite oxide, tetragonal Li-La-Zr composite oxide, La-Li-Al composite oxide, lanthanum oxide, lanthanum hydroxide, lithium zirconate, zirconium oxide, lanthanum zirconate, lithium aluminate, and lithium carbonate were selected as the target components for analysis. Using the RIR method, the mass ratio of each component to the total of the above-mentioned target components was calculated from the integrated intensity of the strongest diffraction peak of each component.

[0143] Furthermore, when the content of cubic Li-La-Zr-Al composite oxide and tetragonal Li-La-Zr composite oxide was measured for the product powders of Experimental Examples 34 and 35 (heated at 900°C for 3 hours) using the method described in "Measurement of the content of each component in the powder heated at 700°C" above, the cubic Li-La-Zr-Al composite oxide was found to be 91% and 93%, respectively, and the tetragonal Li-La-Zr composite oxide was found to be 1% and 0%, respectively. In addition, when the average displacement strength and sample standard deviation were measured for the product powders of Experimental Examples 34 and 35 (heated at 900°C for 3 hours) using the average displacement strength measurement test described later, both the average displacement strength and sample standard deviation were 50.0 MPa or less in all experimental examples.

[0144] The physical properties of each raw material, product powder, and 700°C heated powder were measured using the following method. The results are shown in Tables 1 to 7.

[0145] (Measurement of exothermic or endothermic reaction temperatures accompanied by weight loss) By differential thermal and thermogravimetric analysis, 10 mg of the sample was heated in an atmospheric environment from 25°C to 650°C at a heating rate of 5°C / min, and the temperature at which weight loss occurred and an exothermic or endothermic reaction occurred within the range of 120°C to 600°C was measured. The temperature at which exothermic or endothermic reaction occurred and a weight loss of 5% by mass occurred, with the mass at 120°C being 100% by mass, was defined as the exothermic or endothermic reaction temperature accompanied by weight loss. As a result, the exothermic or endothermic reaction temperatures accompanied by weight loss were 478°C for LiOH and 478°C for La(OH) ３ At 343°C, Al(OH) ３ The temperature was 250°C for [a certain substance] and 438°C for [another substance]. ２ CO ３ La ２ O ３ , ZrO ２ , α-Al ２ O ３ γ-Al ２ O ３ At temperatures below 600°C, no exothermic or endothermic reactions accompanied by weight loss were observed.

[0146] Furthermore, the melting point of LiOH is 462°C, and Al(OH) ３ Its melting point is 300°C, Al(NO３ ) ３ The melting point of is 73°C. Also, Li ２ CO ３ La ２ O ３ , ZrO ２ , α-Al ２ O ３ γ-Al ２ O ３ The melting points of all of them are above 600°C. Therefore, the only ones that meet the criteria of having an exothermic or endothermic reaction temperature accompanied by weight loss, or a melting point of 600°C or less, are LiOH and La(OH) ３ Al(OH) ３ , AlOOH, Al(NO ３ ) ３ Therefore, Li is not applicable. ２ CO ３ La ２ O ３ , ZrO ２ , α-Al ２ O ３ γ-Al ２ O ３ That is the case.

[0147] (Measurement of volume-based cumulative 50% particle size (D50) measured by laser diffraction scattering method) The particle size distribution was measured using a laser diffraction scattering particle size distribution analyzer (HORIBA, LA-960V2). As a pre-dispersion, a small amount of powder was placed in a sufficient amount of dispersion medium and dispersed in a homogenizer, then adjusted to a transmittance of 80 ± 10% in the instrument for measurement. As the dispersion medium, water was used for non-water-soluble powders, xylene for water-soluble powders, and a mixed solvent mainly composed of ethanol was used for the product powder and the powder heated at 700°C. The refractive indices of the compound to be measured and the dispersion medium were set to 1.46 for LiOH and Li ２ CO ３ 1.43, La(OH) ３ to 1.50, La ２ O ３ 1.84, ZrO ２ 1.57, α-Al ２ O ３ and γ-Al ２ O ３ 1.66, Al(OH) ３ 1.57, AlOOH 1.65, Al(NO３ ) ３ The above measurements were performed using the following ratios: 1.54 for the product powder, 2.80 for the powder heated at 700°C, 2.80 for xylene, 1.50 for water, 1.33 for water, and 1.36 for a mixed solvent mainly composed of ethanol.

[0148] (Measurement of BET specific surface area) The specific surface area was measured using a multi-point method (5 points) with a specific surface area and pore distribution analyzer (Tristar II 3020, manufactured by Shimadzu Corporation). The sample for measurement was prepared according to the method described below, depending on the object to be measured. <Each raw material> 0.5 g of powder was weighed into a 3 / 8 inch cell and degassed under vacuum at 150°C for 30 minutes to prepare the sample for measurement. <Product powder> 3.0 g of powder was weighed into a 3 / 8 inch cell and degassed under vacuum at 250°C for 90 minutes to prepare the sample for measurement. <Ceramic slurry> 2 g to 10 g of ceramic slurry was weighed into an aluminum cup, dried in a dryer at 150°C for 15 minutes to 1 hour, and then heated in a tubular furnace under a nitrogen atmosphere at 450°C for 30 minutes. The obtained dried material was crushed in a mortar for 1 minute to form a powder, 0.5 g of the powder was weighed into a 3 / 8 inch cell, and the sample for measurement was prepared by vacuum degassing at 250°C for 90 minutes.

[0149] (Average Displacement Strength Measurement Test) The composite oxide powder to be measured was scattered on the lower pressure plate made of SKS steel of a micro-compression testing machine. Ten particles with a diameter of 15 μm or more and 50 μm or less were randomly selected from the scattered powder. For each selected particle, a load of up to 1000 mN was applied to the particle up to 1000 mN in the vertical direction at a loading speed of 207 mN / sec using the upper pressure indenter made of diamond, which has a circular flat part with a diameter of 200 μm, at 25°C in an atmospheric environment using the micro-compression testing machine (MCT-W500, manufactured by Shimadzu Corporation). The load at which the particle was displaced by 10% was measured as P (N), and the particle diameter d (mm) at which the particle was displaced by 10% was measured. Next, based on the obtained measured values, the displacement strength St (MPa) was calculated using the following formula (1), and the arithmetic mean of the obtained St values ​​of 10 points was taken as the average displacement strength (MPa). The sample standard deviation of the obtained St values ​​of 10 points was also calculated. Displacement strength St = 2.8P / πd ２ (1)

[0150] (Scanning Electron Microscope Observation) The powder was observed using a scanning electron microscope (Regulus 8220, Hitachi High-Technologies Corporation) at an acceleration voltage of 5.0 kV and a magnification of 5000x. The results are shown in Figures 1 to 5.

[0151] (Elemental Content) For the powders of Experimental Examples 1 to 35, the mass percentages of Li, La, Zr, and Al in 100% mass of the total powder were measured using inductively coupled plasma (ICP) emission spectrometry. Using these values, the molar ratios of Li, Zr, and Al to La were calculated. In all examples, Li was in the range of 4.5 to 6.5 mass%, La was in the range of 30 to 60 mass%, Zr was in the range of 10 to 30 mass%, and Al was in the range of 1.0 to 4.5 mass%. The ratios of Li, Zr, and Al to La calculated from these values ​​were 2.17 to 2.50, 0.50 to 0.83, and the results are shown in Tables 1 to 7.

[0152] (Grinding Test) A slurry obtained by mixing 87.7% by mass of xylene and 12.0% by weight of powder was placed in a Nanko container (BHN-30, manufactured by Kinki Container Co., Ltd.) at a volume of 35%, and 2 mm diameter zirconia balls were placed at a volume of 30%, and the mixture was ground at 110 rpm for 30 hours using a ball mill stand. In experimental examples 5, 6, 7, 11-13, 16-19, and 22-24, the pulverized material was separated from the slurry obtained after grinding, and the content of the cubic Li-La-Zr-Al composite oxide component was measured using the method described in "Measurement of the content of each component in the product powder" above. In all cases, the content was 90% by mass or more.

[0153] (BET diameter (D) ＢＥＴ )) From the BET specific surface area value measured by the method described above, the BET diameter (D ＢＥＴ ) (μm) is given by the following formula: D ＢＥＴ =6 / (BET specific surface area (m ２ / g) x true density (g / cm ３ The calculation was performed using the formula shown. The true density of the powder is 5.1 g / cm³. ３ It was calculated as follows.

[0154] (D for D50) ＢＥＴ The ratio (D ＢＥＴ / D50)) D calculated using the same method as D50 measured using the same method as described above.ＢＥＴ It was calculated as a ratio.

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162] In the table, experimental examples marked with an asterisk (*) are outside the scope of the present invention.

[0163] As can be seen from the results of Experimental Example 1, when attempting to produce cubic Li-La-Zr-Al composite oxide powder by first generating Li-La-Zr composite oxide powder and then mixing it with an Al compound, the content of the cubic Li-La-Zr-Al composite oxide component was a low value of less than 75% by mass.

[0164] Furthermore, as can be seen from the results of experimental examples 3, 9, 15, 21, and 27, which used conventionally known suitable amounts of Al (a ratio of Al to La of 0.08), the cubic Li-La-Zr-Al composite oxide component content was not high when heated at a relatively low temperature of 1050°C. On the other hand, when heated at a high temperature of 1150°C, the cubic Li-La-Zr-Al composite oxide component content was high.

[0165] Furthermore, as can be seen from the results of Experimental Example 33, when a much larger amount of Al (a ratio of Al to La of 0.33) than conventional methods was used, a large amount of La-Li-Al composite oxide was generated during the heating process, and a large amount of La-Li-Al composite oxide remained even after heating, making it impossible to increase the content of cubic Li-La-Zr-Al composite oxide. Therefore, after considering various raw materials, as can be seen from the results of Experimental Example 34, it was possible to suppress the amount of La-Li-Al composite oxide generated during the heating process to an appropriate level, and to keep the amount of residual La-Li-Al composite oxide in the product powder low, thus increasing the content of cubic Li-La-Zr-Al composite oxide in the product powder. As can be seen from the results of Experimental Example 35, further consideration of the raw materials made it possible to further increase the content of cubic Li-La-Zr-Al composite oxide.

[0166] Furthermore, in experimental examples 5-7, 11-13, 16-19, and 22-25, which are embodiments of the present invention, heating was performed at a maximum temperature of 1050°C. The resulting cubic Li-La-Zr-Al composite oxide powder had a high content of cubic Li-La-Zr-Al composite oxide components, a large BET specific surface area, and low average displacement strength.

[0167] Furthermore, scanning electron microscope images (Figures 1-4) of experimental examples 5-7, 11-13, 16-19, and 22-25 revealed that the particle binders in the cubic Li-La-Zr-Al composite oxide powder of the embodiment of the present invention have a structure in which gaps exist within the particle binders to some extent and / or retain to some extent the shape of the particles before sintering or fusion.

[0168] On the other hand, in experimental examples 27 to 31, heating was performed at a maximum temperature of 1150°C. Although the content of cubic Li-La-Zr-Al composite oxide components in the obtained cubic Li-La-Zr-Al composite oxide product powder was high, the BET specific surface area was small and the average displacement strength was high. Furthermore, scanning electron microscope images (Figure 5) of experimental examples 27 to 31 showed that the composite oxide particles were strongly sintered or fused, and there were very few gaps in the particle bond.

[0169] Furthermore, it was found that the cubic Li-La-Zr-Al composite oxide component content tends to be higher when the ratio of Al to La (Al / La) in the cubic Li-La-Zr-Al composite oxide powder is within a specific range.

[0170] Furthermore, in the experimental examples of embodiments of the present invention, the grinding process in the grinding test yielded particles with a small average particle size, indicating that the cubic Li-La-Zr-Al composite oxide powder of the embodiment of the present invention is easily reduced in particle size. On the other hand, in experimental examples 27 to 32, the grinding process in the grinding test yielded particles with a larger average particle size than the experimental examples of embodiments of the present invention, indicating that the cubic Li-La-Zr-Al composite oxide powder of experimental examples 27 to 32 is difficult to reduce in particle size. In addition, in the grinding test, experimental examples 27 to 32 showed a larger BET specific surface area compared to the experimental examples of embodiments of the present invention, and D ＢＥＴ The value of / D50 is also extremely small. This indicates that in experimental examples 27 to 32, the pulverization test produced a large amount of extremely fine particles and had a wide particle size distribution, while in experimental examples 5 to 7, 11 to 13, 16 to 19, and 22 to 25, which are embodiments of the present invention, the amount of extremely fine particles produced was small and the particle size distribution was narrow. In particular, among experimental examples 5 to 7, 11 to 13, 16 to 19, and 22 to 25, which are embodiments of the present invention, the closer the ratio of Al to La is to 0.33, the lower the D of the pulverized material. ＢＥＴ The smaller the / D50 value, the easier it is to narrow the particle size distribution of the pulverized material. From the above, it was found that the cubic Li-La-Zr-Al composite oxide powders of experimental examples 5-7, 11-13, 16-19, and 22-25, which are embodiments of the present invention, exhibit excellent pulverization properties, and in particular, the experimental examples in which the ratio of Al to La is closer to 0.33 exhibit even better pulverization properties.

Claims

1. A cubic Li-La-Zr-Al composite oxide powder in which the content of the cubic Li-La-Zr-Al composite oxide component is 85% by mass or more of the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method, and the BET specific surface area is 0.15 m². ２ A cubic Li-La-Zr-Al composite oxide powder characterized by having a concentration of 1 / g or more, and the average displacement strength of the powder measured by the average displacement strength measurement test described below being 50.0 MPa or less. <Average Displacement Strength Measurement Test> Cubic Li-La-Zr-Al composite oxide powder is scattered on the lower pressure plate made of SKS steel of a microcompression testing machine. Ten particles with a diameter of 15 μm or more and 50 μm or less are randomly selected from the scattered powder. For each selected particle, a load of up to 1000 mN is applied to the particle up to 1000 mN using the microcompression testing machine at 25°C in an atmospheric environment, with a diamond upper pressure indenter having a circular flat section with a diameter of 200 μm, at a loading speed of 207 mN / sec in the vertical direction. When the load at which a 10% displacement occurs is P (N) and the particle diameter at which a 10% displacement occurs is d (mm), the displacement strength St (MPa) is calculated using the following formula (1), and the arithmetic mean of the obtained values ​​for the 10 points is taken as the average displacement strength (MPa). Displacement strength St = 2.8P / πd ２ (1) 2. A cubic Li-La-Zr-Al composite oxide powder in which the content of the cubic Li-La-Zr-Al composite oxide component is 85% by mass or more of the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method, and the BET specific surface area is 0.15 m². ２ A cubic Li-La-Zr-Al composite oxide powder characterized by having a concentration of 1 / g or more, and satisfying at least one of the following: (i) the average displacement strength of the powder measured by the average displacement strength measurement test described below is 50.0 MPa or less, and (ii) the ratio of the number of moles of Al on an atomic basis to the number of moles of La on an atomic basis (Al / La) is 0.17 or more and 0.40 or less. <Average Displacement Strength Measurement Test> Cubic Li-La-Zr-Al composite oxide powder is scattered on the lower pressure plate made of SKS steel of a microcompression testing machine. Ten particles with a diameter of 15 μm or more and 50 μm or less are randomly selected from the scattered powder. For each selected particle, a load of up to 1000 mN is applied to the particle up to 1000 mN using the microcompression testing machine at 25°C in an atmospheric environment, with a diamond upper pressure indenter having a circular flat section with a diameter of 200 μm, at a loading speed of 207 mN / sec in the vertical direction. When the load at which a 10% displacement occurs is P (N) and the particle diameter at which a 10% displacement occurs is d (mm), the displacement strength St (MPa) is calculated using the following formula (1), and the arithmetic mean of the obtained values ​​for the 10 points is taken as the average displacement strength (MPa). Displacement strength St = 2.8P / πd ２ (1) 3. A cubic Li-La-Zr-Al composite oxide powder in which the content of the cubic Li-La-Zr-Al composite oxide component is 85% by mass or more of the total of the cubic Li-La-Zr-Al composite oxide component, tetragonal Li-La-Zr composite oxide component, La-Li-Al composite oxide component, lanthanum aluminate component, lithium zirconate component, lithium aluminate component, and lanthanum zirconate component, as calculated by analyzing the measured values ​​by X-ray diffraction using the RIR method, and the BET specific surface area is 0.15 m². ２ The cubic Li-La-Zr-Al composite oxide powder according to claim 2, characterized in that (ii) the ratio of the number of moles of Al on an atomic basis to the number of moles of La on an atomic basis (Al / La) is 0.17 or more and 0.40 or less.

4. The cubic Li-La-Zr-Al composite oxide powder according to any one of claims 1 to 3, characterized in that the sample standard deviation calculated from 10 displacement strength St values ​​obtained in the average displacement strength measurement test is 50.0 MPa or less.

5. The cubic Li-La-Zr-Al composite oxide powder according to claim 1, characterized in that the ratio of the number of moles of Al on an atomic basis to the number of moles of La on an atomic basis (Al / La) is 0.17 or more and 0.40 or less.

6. The cubic Li-La-Zr-Al composite oxide powder according to any one of claims 1 to 3, characterized in that the content of the cubic Li-La-Zr-Al composite oxide component is 90% by mass or more.

7. The cubic Li-La-Zr-Al composite oxide powder according to any one of claims 1 to 3, characterized in that it is for use in solid-state batteries.

8. The cubic Li-La-Zr-Al composite oxide powder according to any one of claims 1 to 3, characterized in that it is for use as a separator in a solid-state battery.

9. A ceramic slurry comprising cubic Li-La-Zr-Al composite oxide powder or pulverized thereof according to any one of claims 1 to 3, and a solvent.

10. A method for producing a ceramic slurry, comprising a grinding step of grinding the cubic Li-La-Zr-Al composite oxide powder according to any one of claims 1 to 3.

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