AMORPHOUS COMPOSITE METAL OXIDE POWDER CONTAINING La AND Zr, POWDER THEREOF, GARNET-TYPE LITHIUM COMPOSITE METAL OXIDE, AND METHOD FOR MANUFACTURING ALL-SOLID BATTERY

Abstract

To provide a technology for synthesizing a lithium composite metal oxide having a garnet-type crystal structure and a high ion conductivity even when fired at a low temperature of 700°C or lower.SOLUTION: An amorphous composite metal oxide powder containing La and Zr, which contains 40 mass% or more and 62 mass% or less of La, 8 mass% or more and 26 mass% or less of Zr, and 1 mass% or more and 20 mass% or less of one or two of metal elements M that can take any oxidation number of 3 to 6, preferably Ta and Nb, which has a carbon content of 1.5 mass% or less, and the remainder of which consists of oxygen and inevitable impurities, is used as a precursor for producing a single-phase garnet-type lithium composite metal oxide.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an amorphous composite metal oxide powder containing La (lanthanum) and Zr (zirconium) and a method for producing the same, to a method for producing a garnet-type lithium composite metal oxide, and to a method for producing an all-solid-state battery using the garnet-type lithium composite metal oxide. [Background technology]

[0002] Compared to conventional secondary batteries, lithium-ion secondary batteries are lighter, have higher capacity, and have higher electromotive force, and therefore are widely used in electronic devices such as personal computers and mobile phones, as well as in automotive batteries, etc. Among these, the development of all-solid-state lithium-ion secondary batteries, which have excellent safety, has been progressing recently.

[0003] Many lithium ion conductors are used as solid electrolytes in all-solid-state batteries. Among them, lithium-containing composite metal oxides with a garnet-type crystal structure are well known. One such garnet-type lithium composite metal oxide is Li7La3Zr2O, which contains Li, La, and Zr. 12 (hereinafter also referred to as "LLZ") and LLZ with various metal elements added are known.

[0004] For example, Patent Document 1 discloses a garnet-type lithium composite metal oxide containing Li, La, and Zr to which Al, Ga, Y, Ce, Ca, Ba, Sr, Nb, and Ta are added in order to enhance ionic conductivity, and the volume-based average particle diameter D 50 The document discloses a garnet-type lithium composite metal oxide containing Li and having a particle size of 0.5 μm to 50 μm. The composite metal oxide is said to be obtained by using a precipitate obtained by reacting a zirconium carbonate complex with a precipitate separated from an aqueous solution containing carbonate ions and La ions as a precursor, and by calcining a mixture obtained by mixing the precursor with a lithium compound.

[0005] Patent Document 2 describes a production method for obtaining a garnet-type lithium composite metal oxide that can be sintered at a low temperature and becomes a sintered body with high ionic conductivity by sintering, in which an amorphous composite metal oxide containing La, Zr, Nb, Ta, V, and Bi is prepared as a raw material for the garnet-type lithium composite metal oxide, and a mixture of the amorphous composite metal oxide and a lithium salt is fired.

[0006] Patent Document 3 discloses a method for producing an amorphous composite oxide containing La and Zr but not containing Li, for use as a precursor for synthesizing composite oxides including garnet-type composite oxides. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6916406 [Patent Document 2] Patent Publication No. 2021-138554 [Patent Document 3] Japanese Patent Application Publication No. 2017-214247 Summary of the Invention [Problem to be solved by the invention]

[0008] In the industrial manufacturing process of all-solid-state batteries, it is generally assumed that an electrode active material and a solid electrolyte are mixed and then a sintering process is carried out to form a good bond between the electrode active material and the solid electrolyte. In the sintering process, the heating temperature is limited to prevent adverse effects such as reaction between the electrode active material and the solid electrolyte, and it is desirable to perform firing and sintering at a temperature range of, for example, about 700°C or less. However, the garnet-type lithium composite metal oxide disclosed in Patent Document 1 does not form a single-phase garnet structure when fired at a low temperature of 700° C. or less, and therefore is thought to have low ionic conductivity.

[0009] The amorphous composite metal oxide powder used as a raw material (precursor) for the garnet-type lithium composite metal oxide disclosed in Patent Document 2 is synthesized by a process involving the esterification of a metal chelate compound and a chelating polymerizer. Therefore, the resulting precursor contains hydrocarbon impurities, resulting in low ionic conductivity. Patent Document 2 also includes statements such as, "Next, the gel obtained by the esterification reaction is calcined. By calcining the gel, the carbon-carbon and carbon-hydrogen bonds contained in the gel are broken and carbonized, resulting in a precursor composed of an amorphous oxide (paragraph 50)." It is also possible that "In the heat treatment step for the precursor, some or all of the organic residues, such as soot, remaining in the precursor may not need to be removed. The organic residues remaining in the precursor are rendered electronically conductive by carbonization. Therefore, if the organic residues are not removed, the precursor will be imparted with electronic conductivity by the organic residues (paragraph 55)." These statements suggest that the amorphous composite metal oxide powder may contain carbon. If amorphous composite metal oxide powder has electronic conductivity, when the metal oxide powder is used as an electrolyte in an electrochemical device, it may cause a partial short circuit, making it undesirable as a solid electrolyte material in an all-solid-state battery. Furthermore, the garnet-type lithium composite oxide produced by the technique disclosed in Patent Document 2 is likely to contain heterogeneous phases due to carbon as an impurity, and is thought to have poor ionic conductivity.

[0010] In the method for producing an amorphous composite oxide containing La and Zr but not Li, described in Patent Document 3, acetate is used as a starting material. The acetate remains as carbonate after thermal decomposition, and in order to completely remove the carbonate, the amorphous powder must be heat-treated at 800°C or higher.

[0011] In order to solve the above problems, the present invention aims to provide an amorphous composite metal oxide powder that can be used as a precursor for synthesizing a garnet-type lithium composite metal oxide, and that can yield a lithium composite metal oxide having a garnet-type crystal structure and high ionic conductivity even when fired at a low temperature of 700° C. or less. Another object of the present invention is to provide a garnet-type lithium composite metal oxide and an all-solid-state battery using the same. [Means for solving the problem]

[0012] [1] To achieve the above object, the present invention provides an amorphous composite metal oxide powder containing La and Zr, which contains 40% by mass or more and 62% by mass or less of La, 8% by mass or more and 26% by mass or less of Zr, and 1% by mass or more and 20% by mass or less of a metal element M that can take any oxidation state of 3 to 6, excluding La and Zr, with a carbon content of 1.5% by mass or less, and the remainder being oxygen and unavoidable impurities. [2] The amorphous composite metal oxide powder containing La and Zr according to item [1] above preferably has a molar ratio of La, Zr, and metal element M in the amorphous composite metal oxide powder of La:Zr:M=3:1.2-1.95:0.05-0.8. [3] In the amorphous composite metal oxide powder containing La and Zr according to the above item [1], the oxidation number that the metal element M can take is preferably pentavalent. [4] In the amorphous composite metal oxide powder containing La and Zr according to the above item [1], the metal element M is preferably one or more of Ta, Nb, V and Sb. [5] The amorphous composite metal oxide powder containing La and Zr according to the above items [1] to [4] preferably has a nitrogen content as an inevitable impurity of 3 mass % or less.

[0013] [6] The present invention also provides a method for producing an amorphous composite metal oxide powder containing La and Zr according to item [1], the method comprising the steps of: obtaining a slurry containing a coprecipitate containing La, Zr, and a metal element M that can have any oxidation number from 3 to 6, excluding La and Zr; recovering the coprecipitate containing La, Zr, and the metal element M from the slurry containing the coprecipitate containing La, Zr, and the metal element M by solid-liquid separation; and heat-treating the recovered coprecipitate containing La, Zr, and the metal element M at a temperature of less than 800°C. [7] In the method for producing an amorphous composite metal oxide powder containing La and Zr according to item [6], the step of obtaining a slurry containing a coprecipitate containing La, Zr, and the metal element M may involve simultaneously dissolving an inorganic La compound, an inorganic Zr compound, and an inorganic metal element M compound in water. [8] In the method for producing an amorphous composite metal oxide powder containing La and Zr according to item [6], the step of obtaining a slurry containing a coprecipitate containing La, Zr, and the metal element M may include the steps of dissolving an inorganic La compound and an inorganic Zr compound in water to prepare an La-Zr-containing aqueous solution, dissolving an inorganic metal element M compound in water to prepare an aqueous solution containing the metal element M, and mixing the La-Zr-containing aqueous solution with the aqueous solution containing the metal element M. [9] In the method for producing an amorphous composite metal oxide powder containing La and Zr according to the above item [6], the heat treatment temperature in the heat treatment step is preferably 700° C. or less.

[10] In the method for producing an amorphous composite metal oxide powder containing La and Zr according to the above item [6], the heat treatment temperature in the heat treatment step is preferably 150° C. or higher.

[11] In the method for producing an amorphous composite metal oxide powder containing La and Zr according to item [7], it is preferable that the inorganic La compound, inorganic Zr compound, and inorganic metal element M compound each do not contain carbon in their molecular structures.

[12] In the method for producing an amorphous composite metal oxide powder containing La and Zr according to item [8], it is preferable that the inorganic La compound, inorganic Zr compound, and inorganic metal element M compound each do not contain carbon in their molecular structures.

[13] In the method for producing an amorphous composite metal oxide powder containing La and Zr according to item [8], it is preferable that the aqueous solution containing the metal element M contains an inorganic metal element M compound, ammonia water, and a peroxo complex of the metal element M produced by mixing hydrogen peroxide with water.

[14] In the method for producing an amorphous composite metal oxide powder containing La and Zr according to the above item [6], the metal element M is preferably one or more of Ta, Nb, V and Sb.

[15] In the method for producing an amorphous composite metal oxide powder containing La and Zr according to item [6], it is preferable that the molar ratio of the contents of La, Zr, and the metal element M in the slurry containing the coprecipitate containing La, Zr, and the metal element M is La:Zr:M=3:1.2-1.95:0.05-0.8.

[16] In the method for producing an amorphous composite metal oxide powder containing La and Zr according to items [6] to

[15] , it is preferable to wash the coprecipitate containing La, Zr, and the metal element M when subjecting the slurry containing the coprecipitate containing La, Zr, and the metal element M to solid-liquid separation.

[0014]

[17] The present invention also provides a method for producing a garnet-type lithium composite metal oxide, which comprises mixing the amorphous composite metal oxide powder containing La and Zr described in the above item [1] with a Li compound and firing the resulting mixture.

[18] In the method for producing a garnet-type lithium composite metal oxide according to the above item

[17] , the temperature for firing the mixture of the amorphous composite metal oxide powder containing La and Zr and the Li compound is preferably 300°C or higher and lower than 700°C.

[19] In the method for producing a garnet-type lithium composite metal oxide according to the item

[17] , when the amorphous composite metal oxide powder containing La and Zr is mixed with a Li compound, the molar ratio of Li, La, Zr and the metal element M is preferably Li:La:Zr:M=6.5-7.5:3:1.2-1.95:0.05-0.8.

[0015]

[20] In the present invention, when manufacturing an all-solid-state battery having a battery unit structured such that a solid electrolyte layer is disposed between a positive electrode layer containing a positive electrode active material and a negative electrode layer containing a negative electrode active material, There is provided a method for producing an all-solid-state battery, in which at least one of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer contains a garnet-type lithium composite metal oxide produced by the production method according to any one of

[17] to

[19] above. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide an amorphous composite metal oxide powder containing La, Zr, and a precursor metal element M that can take on oxidation numbers of 3 to 6, which can be used as a raw material for a garnet-type lithium composite metal oxide that forms a garnet-type crystal structure even when fired at a low temperature of 700°C or less and exhibits high ionic conductivity. It is also possible to provide a method for producing the amorphous composite metal oxide powder, and a suitable method for producing a garnet-type lithium composite metal oxide using the amorphous composite metal oxide powder as a raw material. [Brief explanation of the drawings]

[0017] [Figure 1] 1 shows FT-IR spectra of aqueous solutions of metal element M obtained in Examples 1 and 11. [Figure 2] 1 shows XRD spectra of amorphous composite metal oxide powders of Examples 1, 7, 9, and 10 and composite metal oxide powder of Comparative Example 2. [Figure 3]FIG. 4 shows the charge-discharge characteristics of a battery constructed using a mixture of the composite metal oxide powder obtained in Example 4-2 and a composite oxide containing Li, Ni, Co, and Mn (NCM powder) as the powder for the positive composite electrode, and a mixture of the composite metal oxide powder obtained in Example 4-2 and a composite oxide powder of Li and Ti (LTO powder) as the powder for the negative composite electrode. [Figure 4] FIG. 1 is a cross-sectional view schematically illustrating one embodiment of the configuration of an all-solid-state battery. DETAILED DESCRIPTION OF THE INVENTION

[0018] [Amorphous composite metal oxide powder] In the present invention, an amorphous composite metal oxide powder containing La and Zr is used as a starting material (precursor) for synthesizing a garnet-type lithium composite metal oxide in which some of the metal elements in LLZ, a composite metal oxide with a garnet-type crystal structure containing lithium, are substituted with other metal elements. In order to synthesize a composite metal oxide with a garnet-type crystal structure in which some of the metal elements in LLZ are substituted with other metal elements, the amorphous composite metal oxide powder contains a metal element M other than La and Zr, which will ultimately become the substituting elements. In this case, the metal element M is a metal element that can take any oxidation number from 3 to 6.

[0019] The amorphous composite metal oxide powder containing La and Zr of the present invention must be amorphous. Because amorphous composite metal oxide powders are highly reactive, even when the mixture obtained by mixing them with a Li salt is calcined at a low temperature of 700°C or less, a garnet-type lithium composite metal oxide with high ionic conductivity can be obtained. Here, "amorphous" refers to a case in which, in powder X-ray diffraction (XRD) measurement using CuKα radiation, no clear diffraction peak is observed in the 2θ:10° to 60° region, and a so-called halo pattern appears. The "halo" refers to a gradual rise and fall in X-ray intensity, observed as a broad rise in the XRD spectrum, and the half-width of the halo is 2θ:2° or more.

[0020] The amorphous composite metal oxide powder containing La and Zr of the present invention contains 40% by mass or more and 62% by mass or less of La. By adjusting the La content to 40% by mass or more and 62% by mass or less, a garnet-type lithium composite metal oxide having a single-phase garnet-type crystal structure can be obtained when a mixture of the amorphous composite metal oxide powder and a lithium salt is fired and crystallized. From the viewpoint of making it easier to obtain a single-phase garnet-type crystal structure, the La content is preferably 45% by mass or more, more preferably 48% by mass or more, and preferably 60% by mass or less.

[0021] The amorphous composite metal oxide powder containing La and Zr of the present invention contains 8% by mass or more and 26% by mass or less of Zr. By adjusting the Zr content to 8% by mass or more and 26% by mass or less, a garnet-type lithium composite metal oxide having a single-phase garnet-type crystal structure can be obtained when a mixture of the amorphous composite metal oxide powder and a lithium salt is fired and crystallized. From the viewpoint of making it easier to obtain a single-phase garnet-type crystal structure, the Zr content is preferably 10% by mass or more, more preferably 14% by mass or more, and preferably 25% by mass or less.

[0022] The amorphous composite metal oxide powder containing La and Zr of the present invention contains 1% by mass or more and 20% by mass or less of a metal element M, which is a metal element capable of assuming a trivalent to hexavalent oxidation state, excluding La and Zr. A lithium composite metal oxide having a garnet-type crystal structure contains tetracoordinated lithium ions, forming a tetrahedron with four oxygen ions at its vertices, and hexacoordinated lithium ions, forming an octahedron with six oxygen ions at its vertices. Substitution of the Zr site with a metal element M, capable of assuming a trivalent to hexavalent oxidation state, changes the atomic coordinates of the oxygen ions surrounding the lithium ion. Adjusting the amount of substitution increases the distance between the oxygen ions surrounding the lithium ion, facilitating lithium ion migration and improving ionic conductivity. Therefore, the amorphous composite metal oxide powder must contain 1% by mass or more of the metal element M. Furthermore, since a large content of a metal element M capable of assuming a trivalent to hexavalent oxidation state is thought to decrease ionic conductivity, the metal element M in the amorphous composite metal oxide powder is set to 20% by mass or less. From the viewpoint of ionic conductivity, the content of the metal element M that can take on oxidation numbers of trivalent to hexavalent is preferably 13 mass % or less, more preferably 10 mass % or less, and even more preferably 8 mass % or less.

[0023] In terms of ionic conductivity, the amorphous composite metal oxide powder containing La and Zr preferably contains La, Zr and the metal element M in a molar ratio of La:Zr:M=3:1.2-1.95:0.05-0.8. In the amorphous composite metal oxide powder containing La and Zr, the total molar ratio of La, Zr and M is preferably 4.5 to 5.5, and more preferably 4.75 to 5.25.

[0024] In the amorphous composite metal oxide powder containing La and Zr of the present invention, the metal element M includes a metalloid element. The metal element M, which can have a trivalent to hexavalent oxidation number, is preferably one or more of Ta (tantalum), Nb (niobium), V (vanadium), Sb (antimony), Sc (scandium), Ti (titanium), Y (yttrium), Hf (hafnium), Mo (molybdenum), W (tungsten), Al (aluminum), Si (silicon), Ga (gallium), Ge (germanium), Bi (bismuth), and Sn (tin). From the viewpoint of increasing ionic conductivity, the metal element M is preferably a metal element which can have a pentavalent oxidation number. Among the pentavalent elements, one or more of Ta(0.64), Nb(0.64), Sb(0.60), and V(0.54), which have an ionic radius close to that of Zr(0.72), are preferred, as this allows the lattice volume of the garnet-type lithium composite oxide to be optimized, and one or more of Ta and Nb are more preferred.

[0025] [Carbon content] As described above, the amorphous composite metal oxide powder containing La and Zr of the present invention is composed of La, Zr, the metal element M, and O (oxygen), but also contains C (carbon) that is inevitably mixed in during the manufacturing process. The carbon content of the amorphous composite metal oxide powder is preferably 1.5% by mass or less. By controlling the carbon content to 1.5% by mass or less, the ionic conductivity of the resulting garnet-type lithium composite metal oxide having a garnet-type crystal structure can be increased. It is presumed that reducing the carbon content of the amorphous composite metal oxide powder suppresses the inhibition of Li ion migration in the garnet-type lithium composite metal oxide finally obtained by low-temperature firing at 700°C or less, thereby improving ionic conductivity. The carbon content of the amorphous composite metal oxide powder is more preferably 1.4% by mass or less. However, because carbon is mixed into the amorphous composite metal oxide powder due to carbon dioxide in the air, it is practically difficult to achieve a carbon content of less than 0.01% by mass. Therefore, the lower limit of the carbon content of the amorphous powder is usually 0.01% by mass or more.

[0026] [Nitrogen content] The amorphous composite metal oxide powder containing La and Zr of the present invention is allowed to contain inevitable impurities other than the above-mentioned La, Zr, metal element M, carbon, and O (oxygen) described below, as long as the effects of the present invention are not impaired. Among the inevitable impurities contained in the amorphous composite metal oxide powder, N (nitrogen) is considered to be one that may reduce the ionic conductivity of the final garnet-type lithium composite metal oxide. In the present invention, the nitrogen content of the amorphous powder is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1.5% by mass or less. The lower limit of the nitrogen content is not particularly limited, but may be, for example, 0.1% by mass or more. Furthermore, when the manufacturing method of the present invention described below is used, the amount of unavoidable impurities contained in the amorphous composite metal oxide powder containing La and Zr of the present invention, other than the oxygen and nitrogen mentioned above, becomes negligible.

[0027] [Oxygen content] The amorphous composite metal oxide powder containing La and Zr of the present invention, obtained using the manufacturing method of the present invention described below, contains La, Zr, the metal element M, carbon, and nitrogen, as described above. Therefore, the oxygen content (mass%) contained in the amorphous powder can be calculated using the following formula (1): Oxygen content (mass%) = 100-(La content + Zr content + metal element M content + carbon content + nitrogen content) (mass%) …(1) The oxygen content in the amorphous composite metal oxide powder containing La and Zr of the present invention is preferably 5% by mass or more and 35% by mass or less.

[0028] [BET specific surface area] The amorphous composite metal oxide powder containing La and Zr of the present invention has a BET specific surface area of ​​10 m from the viewpoint of low-temperature sintering. 2 / g or more 150m 2 / g or less. 2 / g or more 150m 2When the BET specific surface area of ​​the amorphous powder is 140 m / g or less, it is presumed that when the mixture obtained by mixing the amorphous powder with a Li salt is fired at a low temperature of 700°C or less, heat is uniformly applied to the mixture, and crystallization proceeds uniformly throughout the particles, thereby improving the ionic conductivity of the garnet-type lithium composite metal oxide that is finally obtained. From the viewpoint of improving ionic conductivity, the BET specific surface area of ​​the amorphous powder is preferably 140 m / g or less. 2 / g or less, more preferably 130m 2 / g or less, more preferably 100m 2 / g or less, more preferably 90m 2 / g or less.

[0029] [Method for producing amorphous composite metal oxide powder] [Starting materials] In the present invention, a wet method is adopted as a method for producing the amorphous composite metal oxide powder containing La and Zr, which is suitable for mass production and has low production costs.

[0030] The method for producing an amorphous composite metal oxide powder containing La and Zr of the present invention includes the steps of obtaining a slurry containing a coprecipitate containing La, Zr, and the metal element M, recovering the coprecipitate containing La, Zr, and the metal element M from the slurry containing the coprecipitate containing La, Zr, and the metal element M by solid-liquid separation, and heat-treating the recovered coprecipitate containing La, Zr, and the metal element M at a temperature of less than 800°C.

[0031] A known coprecipitation method can be used in the step of obtaining a slurry containing a coprecipitate containing La, Zr, and the metal element M. In the present invention, the step of obtaining a slurry containing a coprecipitate containing La, Zr, and the metal element M can take two forms. In the first embodiment, La, Zr, and the metal element M are simultaneously dissolved in water to obtain the slurry. In this case, in order to reduce the carbon content in the amorphous composite metal oxide powder, an inorganic metal compound is used as the starting material for La, Zr, and the metal element M, rather than an organic metal compound containing a hydrocarbon group or a carboxyl group. Examples of inorganic metal compounds that can be used include inorganic La compounds, inorganic Zr compounds, and inorganic metal element M compounds. In a second embodiment, first, an La-Zr-containing aqueous solution is prepared by dissolving La and Zr in water, and a metal element M-containing aqueous solution is prepared by dissolving a metal element M, which is a metal element that can take an oxidation number of 3 to 6, excluding La and Zr, in water, and then these solutions are mixed. In the second embodiment, too, in order to reduce the carbon content in the amorphous composite metal oxide powder, the aforementioned inorganic metal compounds, i.e., an inorganic La compound, an inorganic Zr compound, and an inorganic metal element M compound, can be used as starting materials for La, Zr, and metal element M. The La-Zr-containing aqueous solution may be prepared by simultaneously dissolving the inorganic La compound and the inorganic Zr compound in water, or by mixing an aqueous solution in which an inorganic La compound is dissolved in water with an aqueous solution in which an inorganic Zr compound is dissolved in water.

[0032] Examples of inorganic metal compounds that can be dissolved in water include oxides, hydroxides, nitrates, chlorides, sulfates, and carbonates of La, Zr, and the metal element M. When a carbonate is used as the inorganic metal compound, it is possible to release carbonate ions as a gas by heat-treating a coprecipitate containing La, Zr, and the metal element M (described below) at less than 800°C, thereby reducing the carbon content in the amorphous composite metal oxide powder. However, from the perspective of lowering the heat-treatment temperature, it is preferable to use a metal compound that does not contain carbon in its molecular structure.

[0033] The metal element M is preferably one or more of Ta, Nb, V, and Sb, which can assume a pentavalent oxidation state, and more preferably one or two of Ta and Nb. When the metal element M is a poorly water-soluble metal such as pentavalent Ta, Nb, V, or Sb, it is preferable to use a complexing agent to convert the metal compound into a water-soluble metal complex or a polyacid ion, which is then dissolved in water. Water-soluble metal complexes are preferably peroxo complexes having a peroxy group, since they do not contain carbon in their molecular structure. Peroxo complexes of Ta, Nb, or the like can be obtained by mixing a Ta compound or Nb compound with an alkaline solution such as ammonia water and hydrogen peroxide solution.

[0034] When preparing an aqueous solution of a peroxo complex of Ta or Nb, it is preferable to add and mix an excess amount of ammonium ions in the ammonia water, preferably 3 moles or more, more preferably 10 moles or more, and even more preferably 30 moles or more per mole of Ta or Nb. In addition, to prevent the nitrogen content in the amorphous composite metal oxide powder from increasing, it is preferable to add and mix an excess amount of ammonium ions in the ammonia water, preferably 80 moles or less, more preferably 70 moles or less, and even more preferably 50 moles or less per mole of Ta or Nb.

[0035] It is preferable to add and mix an excess of hydrogen peroxide, preferably 8 moles or more, more preferably 10 moles or more, and even more preferably 30 moles or more, per mole of Ta or Nb. In order to prevent the nitrogen content in the amorphous composite metal oxide powder from increasing, it is preferable to add and mix an excess of hydrogen peroxide, preferably 80 moles or less, more preferably 70 moles or less, and even more preferably 50 moles or less, per mole of Ta or Nb.

[0036] Whether Ta or Nb contained in the aqueous solution is a peroxo complex can be confirmed by FT-IR measurement. When Ta or Nb in the aqueous solution is in the form of a peroxo complex, the wave number of 820 cm -1 ±10cm -1An absorption peak due to the O-O bond of peroxo is observed around this area.

[0037] Polyacids are anionic species formed by condensation of oxoacids, and polyacids of metal element M are metallic acids. It can be considered to be a molecular ion species of Nb oxide. When there is one type of metal element M, it is called an isopolyacid, and when there are multiple metal elements, it is called a heteropolyacid. To prepare an aqueous solution containing Nb polyacid ions, proceed as follows.

[0038] Although the potential-pH diagram for niobium has not yet been established, since hydroxides of niobium precipitate in the neutral region, it is thought that solid phases such as Nb(OH)5 or HNbO3 are stable species in this pH region. When an alkali is added to an aqueous solution containing these solid phases to raise the pH of the system, excess OH - The presence of ions causes niobium to react with, for example, Nb(OH)6 - and NbO3 - It begins to dissolve in the form of, etc. If the pH of the system is further increased, it is thought that the soluble niobium oxide will take on various condensation states depending on the pH of the system, but in this specification, it is thought that niobium oxide solubilized on the alkaline side will collectively become niobium polyacid ions. The fact that niobium in an aqueous solution is a polyacid ion can be confirmed by FT-IR measurement. When niobium in an aqueous solution takes the form of a polyacid ion, it will be -1 ±10cm -1 An absorption peak due to the Nb-O bond is observed around 680 ± 20 cm -1 An absorption peak due to the Nb-O-Nb bond is observed around

[0039] [Coprecipitate production and recovery] In the method of the present invention for producing an amorphous composite metal oxide powder containing La and Zr, the La-Zr-containing aqueous solution and the metal element M-containing aqueous solution prepared in the above steps are mixed under stirring conditions, and the pH of the mixed aqueous solution is adjusted to preferably 10 to 12, thereby producing a coprecipitate of mixed hydroxides of La, Zr, and metal element M, and obtaining a slurry containing the coprecipitate. Even when the La-Zr-containing aqueous solution described below is acidic and the metal element M-containing aqueous solution is alkaline, the component elements can be uniformly coprecipitated by stirring and mixing while maintaining the pH of the mixed solution within the above range.

[0040] The molar ratio of La, Zr, and the metal element M contained in the slurry is preferably La:Zr:M=3:1.2-1.95:0.05-0.8. The total molar ratio of La, Zr, and the metal element M contained in the slurry is preferably 4.5-5.5, and more preferably 4.75-5.25. If the pH of the mixed aqueous solution is less than 10, the component elements may not co-precipitate uniformly, which may result in compositional variations in the resulting amorphous composite metal oxide powder. If the pH of the mixed aqueous solution exceeds 12, the amount of alkali added to adjust the pH increases, which is undesirable because it increases production costs.

[0041] The molar ratio of La, Zr, and the metal element M contained in the coprecipitate is preferably La:Zr:M=3:1.2-1.95:0.05-0.8. The total molar ratio of La, Zr, and the metal element M contained in the coprecipitate is preferably 4.5-5.5, and more preferably 4.75-5.25.

[0042] The coprecipitation method achieves a supersaturated state in which the ion concentration product of the constituent elements in the mixed slurry is higher than the solubility product, which contributes to improving the uniformity of the constituent elements and makes it possible to obtain the amorphous composite metal oxide powder of the present invention. It is believed that the slurry contains constituent elements that have precipitated as hydroxides and constituent elements that exist as ions.

[0043] When a pentavalent metal peroxo complex aqueous solution or an aqueous solution containing polyacid ions is used as the metal element M-containing aqueous solution, the aqueous solution itself is alkaline, so that the pH of the aqueous solution obtained by mixing the La-Zr-containing aqueous solution and the metal element M-containing aqueous solution automatically falls within the above-mentioned preferred pH range, and hydroxides co-precipitate to obtain a slurry.

[0044] When the pH of the mixed aqueous solution is less than 10, an alkaline aqueous solution having a pH greater than 10 is added to adjust the pH of the mixed aqueous solution to the above-mentioned preferred range, thereby forming a coprecipitate. In this case, the alkaline aqueous solution to be added may be an aqueous solution of an alkali metal or alkaline earth hydroxide or carbonate, or ammonia water, but it is preferable to use ammonia water, which is less likely to leave impurities in the finally obtained garnet-type lithium composite metal oxide. The mixed slurry preferably contains La at 1% by mass or more and 5% by mass or less, Zr at 0.2% by mass or more and 2.5% by mass or less, and metal element M at 0.01% by mass or more and 1% by mass or less.

[0045] The coprecipitate obtained in the above step is recovered from the slurry containing the coprecipitate containing La, Zr, and the metal element M using solid-liquid separation means. Known solid-liquid separation means such as filter filtration, ultrafiltration, and centrifugation may be used. In this process, it is preferable to wash the recovered coprecipitate to reduce the amount of impurities, such as ammonia, remaining in the precipitate. From the perspective of reducing the amount of impurities, such as ammonia, remaining in the precipitate, it is preferable to wash the coprecipitate until the pH of the wash water is 9 or less. By washing the wash water until the pH is 9 or less, the amount of ammonia and other impurities remaining in the precipitate can be reduced. This reduces the nitrogen content in the amorphous composite metal oxide powder containing La and Zr.

[0046] [Heat treatment] In the method for producing an amorphous composite metal oxide powder containing La and Zr of the present invention, the coprecipitate containing La, Zr, and the metal element M recovered in the above step is heat-treated in air or in an inert atmosphere (nitrogen, argon, etc.) to obtain an amorphous composite metal oxide powder containing La and Zr, which is a precursor for synthesizing a garnet-type lithium composite metal oxide. The heat treatment temperature is set to less than 800°C. Heat treatment temperatures of 800°C or higher are not preferred because the composite metal oxide powder containing La and Zr may crystallize and assume a fluorite-type crystal structure. The heat treatment temperature is more preferably 700°C or lower, and even more preferably 600°C or lower. In the present invention, the heat treatment time is not particularly specified, but from a process standpoint, the heat treatment time is preferably 1 hour or longer and 6 hours or shorter. From the viewpoint of reducing the nitrogen content of the coprecipitate, the temperature of the heat treatment is preferably 150°C or higher, more preferably 300°C or higher, and even more preferably 400°C or higher.

[0047] In the method for producing an amorphous composite metal oxide powder containing La and Zr according to the present invention, a drying step for removing water from the coprecipitate may be carried out before the heat treatment step, in which case the drying temperature is preferably 80 to 110°C.

[0048] [Garnet-type lithium mixed metal oxide] By using the amorphous composite metal oxide powder containing La and Zr obtained by the above process, a single-phase garnet-type lithium composite metal oxide having high ionic conductivity can be obtained even when a mixture of the amorphous powder and a Li compound is fired at a low temperature of 600°C or less, which is 700°C or less.

[0049] From the viewpoint of ionic conductivity, it is preferable that the garnet-type lithium composite metal oxide is single-phase. Whether the composite metal oxide is garnet-type or not can be confirmed by comparing the XRD spectrum measured using an X-ray diffractometer (XRD) with the diffraction pattern of a garnet-type oxide (garnet-type structure of space group Ia-3d) stored in an electronic computer attached to the apparatus. Also, whether the garnet-type lithium composite metal oxide is single-phase or not can be confirmed in the same manner.

[0050] The garnet-type lithium composite metal oxide of the present invention preferably has the general formula Li7La3Zr 2-y M y O 12 where M is a metal element that can have an oxidation number of +3 to +6. y is a value satisfying 0 < y ≤ 1.0. Also, from the relationship between the ionic conductivity and the lattice volume when it is a garnet-type lithium composite oxide, it is preferably 0.05 ≤ y ≤ 0.8. The metal element M that can have an oxidation number of +3 to +6 includes metalloid elements such as Ge and Si. The metal element M is preferably one or more of Ta, Nb, V, Sb, Sc, Ti, Y, Hf, Mo, W, Al, Si, Ga, Ge, and Sn. In order to increase the ionic conductivity, one or more of Ta, Nb, V, and Sb that can have an oxidation number of +5 are more preferable, and Ta and Nb are even more preferable. The garnet-type lithium composite metal oxide of the present invention has an ionic conductivity of 9.0×10 -6 S / cm or more even when it is a garnet-type lithium composite metal oxide obtained at a firing temperature of 600°C or lower in the measurement of ionic conductivity described later.

[0051] [Method for producing garnet-type lithium composite metal oxide] In the method for producing a garnet-type lithium composite metal oxide of the present invention, a mixture of an amorphous composite metal oxide powder obtained by the method for producing an amorphous composite metal oxide powder containing La and Zr and a Li compound is fired to obtain a garnet-type lithium composite metal oxide.

[0052] The Li compound to be mixed with the amorphous composite metal oxide powder can be an inorganic lithium compound such as Li2O, Li2O2, or Li(OH). The mixing ratio of the amorphous powder and the Li compound is preferably adjusted so that the molar ratio of Li, La, Zr, and the metal element M is Li:La:Zr:M = 6.5-7.5:3:1.2-1.95:0.05-0.8. The mixing ratio of the amorphous powder and the Li compound is preferably such that the total molar ratio of Li, La, Zr, and the metal element M is 11-13, more preferably 11.5-12.5.

[0053] The mixing method is not particularly limited in the method for producing the garnet-type lithium composite metal oxide of the present invention, but may be wet or dry mixing using a known mixing device such as a mixer or ball mill.

[0054] The mixture is preferably fired in a decarbonated atmosphere or an inert atmosphere (nitrogen, argon, etc.) By firing in a decarbonated atmosphere or an inert atmosphere (nitrogen, argon, etc.), moisture and carbonic acid in the atmosphere are adsorbed, and the generation of a different phase such as lithium carbonate in the garnet-type lithium composite metal oxide can be suppressed. The firing temperature of the mixture is preferably 300° C. or higher but lower than 700° C., more preferably 600° C. or lower, from the viewpoint of obtaining a garnet-type lithium composite metal oxide at a low temperature. From the viewpoint of obtaining a garnet-type lithium composite metal oxide with higher ionic conductivity, firing at a temperature of 400° C. or higher is preferred.

[0055] [All-solid battery] FIG. 4 shows a schematic cross-sectional view of one embodiment of the configuration of an all-solid-state battery. A positive electrode layer and a negative electrode layer face each other with a solid electrolyte layer sandwiched therebetween. The embodiment shown in FIG. 4 is an example of an all-solid-state battery having one battery unit composed of a positive electrode layer, a solid electrolyte layer, and a negative electrode layer. The positive electrode layer contains a positive electrode active material and, if necessary, a solid electrolyte exhibiting lithium ion conductivity or a conductive additive that is a conductor. The negative electrode layer contains a negative electrode active material and, if necessary, a solid electrolyte exhibiting lithium ion conductivity or a conductive additive that is a conductor. The solid electrolyte layer is composed of one or more solid electrolytes exhibiting lithium ion conductivity. The exchange of electrons with the outside during charging and discharging of the battery is usually carried out via current collectors arranged in contact with the positive electrode layer and the negative electrode layer, respectively. The garnet-type lithium composite metal oxide obtained according to the present invention is useful as a solid electrolyte to be contained in a positive electrode layer, a solid electrolyte to be contained in a negative electrode layer, and a solid electrolyte to be contained in a solid electrolyte layer.

[0056] An all-solid-state battery using the above-described garnet-type lithium composite metal oxide obtained according to the present invention can be obtained, for example, by a method for producing an all-solid-state battery having a battery unit structured such that a solid electrolyte layer is disposed between a positive electrode layer containing a positive electrode active material and a negative electrode layer containing a negative electrode active material, and at least one of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer is formed from one containing the above-described garnet-type lithium composite metal oxide.

[0057] In addition to known materials, new positive electrode active materials may also be developed and applied. Typical known positive electrode active materials include LiCoO2 (LCO type), LiNiO2 (LNO type), LiMn2O4 (LMO type), LiNiCoAlO2 (NCA type), LiNiCoMnO2 (NCM type), Li2MnO3-LiNiCoMnO2 (solid solution type), LiNiMnO4 (spinel type), LiMnFePO4 (phosphate type), and Li2FeSiO4 (silicate type).

[0058] In addition, known materials can be used as the negative electrode active material, and new negative electrode active materials can also be developed and applied. Representative known negative electrode active materials include carbonaceous materials such as natural graphite, artificial graphite, resin carbon, carbon fiber, activated carbon, hard carbon, and soft carbon; conductive polymers such as polyacene, polyacetylene, and polypyrrole; metal materials such as lithium, tin, silicon, gallium, indium, and aluminum; alloy materials such as lithium alloys, tin alloys, silicon alloys, gallium alloys, indium alloys, and aluminum alloys; inorganic compounds such as lithium compounds, tin compounds, silicon compounds, gallium compounds, indium compounds, aluminum compounds, and titanium-niobium oxides. Examples of lithium compounds include lithium-titanium composite oxides, for example, Li4Ti5O 12 is preferred.

[0059] The solid electrolyte constituting the solid electrolyte layer may be a part or all of the garnet-type lithium composite metal oxide obtained according to the present invention, or may be a solid electrolyte other than the garnet-type lithium composite metal oxide obtained according to the present invention. Applicable solid electrolytes include the garnet-type lithium composite metal oxides obtained according to the present invention, as well as garnet-type lithium composite metal oxides containing Li, La, and Zr, such as Li7La3Zr2O. 12 NASICON-type lithium composite metal oxides containing Li, Al, Ge, and P. For example, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, a NASICON-type lithium composite metal oxide containing Li, Al, Ti, and P, e.g., Li 1.5 Al 0.5 Ti 1.5 (PO4)3, a perovskite-type lithium complex metal oxide containing La, Li, and Ti, e.g., La 0.55 Li 0.35 Examples include known materials such as γII-Li3VO4 type lithium composite metal oxides containing TiO3, Li, and V. [Example]

[0060] [Elemental analysis] A 0.05 g powder sample was taken from the amorphous composite metal oxide powder containing La and Zr or the garnet-type lithium composite metal oxide powder obtained in the examples and comparative examples, and dissolved in 2 ml of 35 mass% hydrochloric acid, 2 ml of 60 mass% nitric acid, and 2 ml of 47.5 mass% sulfuric acid. The resulting solution was diluted to a constant volume as needed, and then subjected to elemental analysis using an inductively coupled plasma atomic emission spectrometer (ICP-AES, CP-720 manufactured by Agilent Technologies, Inc.) to calculate the contents of the constituent elements in the powder sample.

[0061] [Measurement of carbon content] The carbon content in the powders obtained in the examples and comparative examples was analyzed using a trace carbon analyzer (EMIA-U510, manufactured by Horiba, Ltd.). [Measuring nitrogen content] The nitrogen content in the powders obtained in the examples and comparative examples was analyzed using a nitrogen analyzer (EMGA-920 manufactured by Horiba, Ltd.).

[0062] [BET specific surface area measurement] The BET specific surface area of ​​the amorphous composite metal oxide powders containing La and Zr obtained in the examples and comparative examples was measured by the BET single-point method using a BET specific surface area measuring device (Macsorb, manufactured by Mountec Co., Ltd.) The measurement was carried out by flowing nitrogen gas into the measuring device at 105°C for 20 minutes to degas it, and then flowing a mixed gas of nitrogen and helium (nitrogen: 30 vol%; helium: 70 vol%).

[0063] [XRD measurement conditions] XRD measurements were carried out under the following measurement conditions for the amorphous composite metal oxide powders containing La and Zr or the garnet-type lithium composite metal oxide powders obtained in the examples and comparative examples. Measurement equipment: XRD-6100 (Shimadzu Corporation) Tube:Cu Tube voltage: 40kv Tube current: 30mA Divergence slit: 1.0° Scattering slit: 1.0° Receiving slit: 0.3 mm Step width: 0.02° / step Measurement time: 0.25 seconds The peak search was performed using Shimadzu XRD-6100 software. The peak search conditions were as follows: Smoothing: Automatic Background processing: Automatic Ka1-a2 ratio: 50 Peak search: Automatic

[0064] [Measurement of ionic conductivity] A 0.15 g sample of powder was taken from the garnet-type lithium composite metal oxide powder obtained in each of the Examples and Comparative Examples. A 10 mm diameter cylindrical container was filled with a powder sample. After the temperature reached 340°C, the sample was hot-pressed at 360 MPa for 2 hours using a press to produce a powder compact with a thickness of 0.5 to 1 mm. The powder compact was subjected to AC impedance measurements in the range of 100 Hz to 4 MHz at 25°C in an air atmosphere using a potentio / galvanostat (Solartron 1470E) and a frequency response analyzer (Solartron 1255B). The measured values ​​were plotted as a Cole-Cole plot (complex impedance plane plot). The intercepts were used to determine the resistance of the garnet-type lithium composite metal oxide powder compact. The ionic conductivity was calculated from the resulting resistance.

[0065] [FT-IR measurement] The FT-IR spectrum of the aqueous solution of metal element M (described later) was measured using a JASCO FT-IR instrument (FT-IR 4X) with water as the reference sample. The measurement was performed using the single-reflection ATR method with an incident angle of 45° onto a germanium prism.

[0066] [Example 1] In this example, Ta with an oxidation state of 5 was used as the metal element M. 4.50 g of TaCl5 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), an inorganic metal element M compound that does not contain hydrocarbon groups in its molecular structure, was mixed with 100 g of pure water and stirred to prepare a slurry containing a Ta-containing precipitate. The slurry containing the Ta-containing precipitate was filtered and washed using a 0.5 μm membrane filter to recover the Ta-containing precipitate. The recovered Ta-containing precipitate was transferred to a 1 L beaker, repulped in 400 g of pure water, and then heated to 40°C. After heating, 40.0 g of 28% by mass ammonia water (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 30 g of 35% by mass hydrogen peroxide water (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to the solution, and the mixture was stirred until the Ta-containing precipitate was dissolved, yielding a metal element M aqueous solution. A small amount of the resulting metal element M aqueous solution was sampled and subjected to FT-IR measurement, revealing a peak at 820 cm -1 ±10cm -1 Since an absorption peak due to the O--O bond of peroxo was observed, it was confirmed that a peroxo complex of Ta was formed in the aqueous solution of the metal element M. FIG. 1 shows the FT-IR spectrum of the aqueous solution containing Ta as the metal element M obtained in this example.

[0067] Next, 32.7 g of lanthanum nitrate hexahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.), an inorganic La compound, and 1.01 g of zirconium oxynitrate dihydrate (Kishida Chemical Co., Ltd.), a Zr compound that does not contain hydrocarbon groups in its molecular structure, were added to 400 g of pure water, and the mixture was heated to 40°C with stirring to dissolve, yielding a La-Zr-containing aqueous solution.

[0068] Next, the La-Zr-containing aqueous solution was added to the metal element M aqueous solution to generate a coprecipitate containing La, Zr, and Ta, thereby obtaining a slurry containing the coprecipitate. The La-Zr-containing aqueous solution was continuously added to the metal element M aqueous solution at 10 g / min so that the molar ratio of La, Zr, and Ta in the slurry was La:Zr:Ta=3:1.5:0.5. The pH of the slurry at this time was 10.5. The slurry was then filtered and washed until the pH of the filtrate reached 9 or less, and the coprecipitate was recovered. The recovered coprecipitate was dried at 100°C for 8 hours to obtain a coprecipitate powder. The dried coprecipitate powder was heated at 500°C for 6 hours in an air atmosphere to obtain a composite metal oxide powder containing La and Zr according to Example 1. When the composite metal oxide powder was subjected to XRD measurement, no clear diffraction peaks were observed in the XRD spectrum, but a halo was observed in the 2θ:10° to 60° region, indicating that the composite metal oxide powder was an amorphous powder. The XRD spectrum of the composite metal oxide powder obtained in Example 1 is shown in FIG.

[0069] The carbon content of the composite metal oxide powder was 0.7 mass %. The production conditions for obtaining the amorphous composite metal oxide powder containing La and Zr of this example are shown in Table 1. Table 2 also shows the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the amorphous composite metal oxide powder containing La and Zr.

[0070] 2.5 g of the amorphous composite metal oxide powder containing La and Zr obtained in Example 1 above and 0.393 g of lithium oxide (manufactured by Kojundo Chemical Laboratory) were mixed for 4 hours at 350 rpm using a planetary ball mill (Fritsch P-7) with φ5 mm zirconia balls to obtain a mixture containing La, Zr, Ta, and Li. In this case, the molar ratio of Li, La, Zr, and Ta in the mixture was Li:La:Zr:Ta=7:3:1.5:0.5. A portion of the obtained mixture was taken and calcined in a nitrogen atmosphere at 400°C for 12 hours to obtain the lithium-containing composite metal oxide powder of Example 1-1. XRD measurement of the composite metal oxide powder revealed clear diffraction peaks in the XRD spectrum. When the diffraction peak was checked against a database built into the computer attached to the XRD device, it was found to match that of a garnet-type oxide (garnet-type structure of space group Ia-3d), confirming that the lithium-containing composite metal oxide powder of Example 1-1 was a garnet-type lithium composite metal oxide. It was also confirmed that the garnet-type lithium composite metal oxide was a single phase.

[0071] Next, a lithium-containing composite metal oxide powder according to Example 1-2 was obtained using the same procedure as in Example 1-1, except that the firing temperature was set to 600°C. This composite metal oxide powder was also a single-phase garnet-type lithium composite metal oxide.

[0072] The garnet-type lithium composite metal oxide powders obtained in Examples 1-1 and 1-2 were subjected to elemental analysis, XRD measurement, and ionic conductivity measurement. The measurement results are shown in Table 3. The ionic conductivity of the compacted powders of the garnet-type lithium composite metal oxide powders according to Examples 1-1 and 1-2 was 2.3 × 10 -5 S / cm and 3.4 × 10 -5 It was S / cm.

[0073] [Example 2] A slurry containing a coprecipitate of La, Zr, and Ta according to Example 2 was obtained using the same procedure as in Example 1, except that 2.25 g of TaCl5 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 100 g of purified water and 11.8 g of zirconium oxynitrate dihydrate (manufactured by Kishida Chemical Co., Ltd.) was added. The molar ratio of La, Zr, and Ta in the resulting mixed slurry was La:Zr:Ta = 3:1.75:0.25, and the pH of the slurry was 10.7. A composite metal oxide powder containing La and Zr according to Example 2 was also obtained using the same procedure as in Example 1. XRD measurement confirmed that the composite metal oxide powder was amorphous. The carbon content of the composite metal oxide powder was 0.8 mass%.

[0074] The manufacturing conditions for Example 2 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the amorphous composite metal oxide powder containing La and Zr obtained in Example 2 are shown in Table 2.

[0075] Lithium-containing composite metal oxide powders according to Examples 2-1 and 2-2 were obtained using the same procedures as in Examples 1-1 and 1-2, except that the amorphous composite metal oxide powder containing La and Zr obtained in Example 2 was used. XRD measurements confirmed that all of the powders were single-phase garnet-type lithium composite metal oxides. The garnet-type lithium composite metal oxide powders obtained in Examples 2-1 and 2-2 were subjected to elemental analysis, XRD measurement, and ionic conductivity measurement, and the results are shown in Table 3. The ionic conductivity of the compacted powders of the garnet-type lithium composite metal oxide powders according to Examples 2-1 and 2-2 was 1.7 × 10 -5 S / cm and 2.5 × 10 -5 It was S / cm.

[0076] [Example 3] A slurry containing a coprecipitate of La, Zr, and Ta according to Example 3 was obtained using the same procedure as in Example 1, except that 0.90 g of TaCl5 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 100 g of purified water and 2.8 g of zirconium oxynitrate dihydrate (manufactured by Kishida Chemical Co., Ltd.) was added. The molar ratio of La, Zr, and Ta in the resulting mixed slurry was La:Zr:Ta = 3:1.90:0.10, and the pH of the slurry was 10.7. A composite metal oxide powder containing La and Zr according to Example 3 was also obtained using the same procedure as in Example 1. XRD measurement confirmed that the composite metal oxide powder was amorphous. The carbon content of the composite metal oxide powder was 0.7 mass%.

[0077] The manufacturing conditions for Example 3 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the amorphous composite metal oxide powder containing La and Zr obtained in Example 3 are shown in Table 2.

[0078] Lithium-containing composite metal oxide powders according to Examples 3-1 and 3-2 were obtained using the same procedures as in Examples 1-1 and 1-2, except that the amorphous composite metal oxide powder containing La and Zr obtained in Example 3 was used. XRD measurements confirmed that all of the powders were single-phase garnet-type lithium composite metal oxides. The garnet-type lithium composite metal oxide powders obtained in Examples 3-1 and 3-2 were subjected to elemental analysis, XRD measurement, and ionic conductivity measurement, and the results are shown in Table 3. The ionic conductivity of the garnet-type lithium composite metal oxide powders according to Examples 3-1 and 3-2 was 1.3 × 10 -5 S / cm and 1.4 × 10 -5 It was S / cm.

[0079] [Example 4] 2.26 g of Nb(OH)5 (manufactured by Taniobis), a compound of metal element M with a pentavalent oxidation state and containing no hydrocarbon groups in its molecular structure, was mixed with 400 g of pure water and heated to 40°C to obtain a slurry containing a precipitate of Nb hydroxide. After heating, 40.0 g of ammonia water with a concentration of 28% by mass and 30 g of hydrogen peroxide water with a concentration of 35% by mass (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to the solution and stirred until the precipitate dissolved, obtaining an aqueous solution of metal element M according to Example 4. FT-IR measurement of the aqueous solution of metal element M showed a peak at 820 cm -1 ±10cm -1 Since an absorption peak due to the O-O bond of peroxo was observed, it was confirmed that a peroxo complex of Nb was formed in the aqueous solution.

[0080] Next, a slurry containing a coprecipitate of La, Zr, and Nb according to Example 4 was obtained using the same procedure as in Example 1, except that the molar ratio of the La, Zr, and Nb contents in the slurry was La:Zr:Nb=3:1.50:0.50. In this case, the pH of the slurry was 10.5. Furthermore, a composite metal oxide powder containing La and Zr according to Example 4 was obtained using the same procedure as in Example 1. XRD measurement confirmed that the composite metal oxide powder was amorphous. The carbon content of the composite metal oxide powder was 0.6% by mass.

[0081] The manufacturing conditions for Example 4 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the amorphous composite metal oxide powder containing La and Zr obtained in Example 4 are shown in Table 2.

[0082] Lithium-containing composite metal oxide powders according to Examples 4-1 and 4-2 were obtained in the same manner as in Examples 1-1 and 1-2, except that the amorphous composite metal oxide powder containing La and Zr obtained in Example 4 was used. XRD measurements confirmed that all of the powders were single-phase garnet-type lithium composite metal oxides. The garnet-type lithium composite metal oxide powders obtained in Examples 4-1 and 4-2 were subjected to elemental analysis, XRD measurement, and ionic conductivity measurement, and the results are shown in Table 3. The ionic conductivity of the compacted powder of the garnet-type lithium composite metal oxide powders according to Examples 4-1 and 4-2 was 2.2 × 10 -5 S / cm and 3.1 × 10 -5 It was S / cm.

[0083] Furthermore, the garnet-type lithium composite metal oxide powder according to Example 4-2 was hot-pressed after reaching 400°C (Example 4-2a), 500°C (Example 4-2b), or 600°C (Example 4-2c) to produce a powder compact. The ionic conductivity of the produced powder compact was measured in the same manner as in the above-described measurement of ionic conductivity, except that the ionic conductivity of Example 4-2a was 4.0 × 10 -5 S / cm, Example 4-2b is 6.5 × 10 -5 S / cm, Example 4-2c is 1.8 × 10 -4 It was S / cm.

[0084] [Charge and discharge characteristics measurement of all-solid-state batteries] Li1Ni as the positive electrode active material 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM manufactured by Toda Kogyo Co., Ltd.) powder was used as the negative electrode active material. 12 A powder of LTO (manufactured by Ishihara Sangyo Kaisha) and a powder of the garnet-type lithium composite metal oxide obtained in Example 4-2 were prepared, and each powder was dried in a vacuum at 200° C. for 12 hours to remove moisture.

[0085] Next, the above-mentioned positive electrode active material powder dried at 200°C and the powder of the garnet-type lithium composite metal oxide of Example 4-2 were mixed in a mass ratio of 50:50 in an agate mortar under a dry environment to prepare a powder sample for a positive electrode composite electrode. Also, the above-mentioned negative electrode active material powder dried at 200°C and the powder of the garnet-type lithium composite metal oxide were mixed in a mass ratio of 50:50 under a dry environment in an agate mortar to prepare a powder sample for a negative electrode composite electrode.

[0086] Next, a platinum and gold (Pt+Au) current collector plate, 18 mg of the powder of the positive electrode material obtained by the above procedure, 100 mg of the powder of the garnet-type lithium composite metal oxide obtained in Example 4-2, 14 mg of the powder of the negative electrode material obtained by the above procedure, and a gold (Au) current collector plate were stacked in a φ10 mm cylinder in the order described above, pressed at 375 MPa in an air atmosphere, and sintered by firing at 300°C for 2 hours to form a battery cell (all-solid-state battery) with the configuration shown in Figure 4. This battery cell has a structure in which three-layered sintered pellets of a positive electrode composite electrode, a garnet-type lithium composite metal oxide, and a negative electrode composite electrode are sandwiched between current collectors (a platinum and gold plate on the positive electrode side and a gold plate on the negative electrode side). The positive electrode composite electrode portion, the garnet-type lithium composite metal oxide portion, and the negative electrode composite electrode portion constituting the three-layered sintered pellets correspond to the positive electrode layer, solid electrolyte layer, and negative electrode layer in Figure 4, respectively.

[0087] Using a charge / discharge measuring device (HOKUTO DENKO HJ1020mSD8), the battery cell prepared by the above procedure was charged and discharged 10 times at a constant current density of 0.021 mA / cm2 (3 mA / g per unit mass of LTO) at 60°C in the voltage range of 1.0 to 3.0 V, and the charge / discharge characteristics of the battery were evaluated. The fabricated battery cell showed a flat charge / discharge region around 2 V, and a good charge / discharge curve was obtained, confirming that charging and discharging could be performed at 60°C. Figure 3 shows an example of measurement of charge and discharge characteristics.

[0088] [Example 5] A slurry containing a coprecipitate of La, Zr, and Nb according to Example 5 was obtained using the same procedure as in Example 4, except that 1.13 g of Nb(OH)5 (manufactured by Taniobis) was mixed with 400 g of pure water and 11.8 g of zirconium oxynitrate dihydrate (manufactured by Kishida Chemical) was added. The molar ratio of La, Zr, and Nb in the resulting mixed slurry was La:Zr:Ta = 3:1.75:0.25, and the pH of the slurry was 10.8. A composite metal oxide powder containing La and Zr according to Example 5 was also obtained using the same procedure as in Example 1. XRD measurement confirmed that the composite metal oxide powder was amorphous. The carbon content of the composite metal oxide powder was 0.7 mass%.

[0089] The manufacturing conditions for Example 5 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the amorphous composite metal oxide powder containing La and Zr obtained in Example 5 are shown in Table 2.

[0090] Lithium-containing composite metal oxide powders according to Examples 5-1 and 5-2 were obtained in the same manner as in Examples 1-1 and 1-2, except that the amorphous composite metal oxide powder containing La and Zr obtained in Example 5 was used. XRD measurements confirmed that all of the powders were single-phase garnet-type lithium composite metal oxides. The results of elemental analysis, XRD measurement, and ionic conductivity measurement of the garnet-type lithium composite metal oxide powders obtained in Examples 5-1 and 5-2 are shown in Table 3. The ionic conductivity of the compacted powders of the garnet-type lithium composite metal oxide powders according to Examples 5-1 and 5-2 was 1.7 × 10 -5 S / cm and 2.2 × 10 -5 It was S / cm.

[0091] [Example 6] A slurry containing a coprecipitate of La, Zr, and Nb according to Example 6 was obtained using the same procedure as in Example 4, except that 0.45 g of Nb(OH)5 (manufactured by Taniobis) was mixed with 400 g of pure water and 12.8 g of zirconium oxynitrate dihydrate (manufactured by Kishida Chemical) was added. The molar ratio of La, Zr, and Nb content in the resulting mixed slurry was La:Zr:Ta = 3:1.90:0.10, and the pH of the slurry was 10.8. A composite metal oxide powder containing La and Zr according to Example 6 was also obtained using the same procedure as in Example 1. XRD measurement confirmed that the composite metal oxide powder was amorphous. The carbon content of the composite metal oxide powder was 0.6 mass%.

[0092] The manufacturing conditions for Example 6 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the amorphous composite metal oxide powder containing La and Zr obtained in Example 6 are shown in Table 2.

[0093] Lithium-containing composite metal oxide powders according to Examples 6-1 and 6-2 were obtained using the same procedures as in Examples 1-1 and 1-2, except that the amorphous composite metal oxide powder containing La and Zr obtained in Example 6 was used. XRD measurements confirmed that all of the powders were single-phase garnet-type lithium composite metal oxides. The results of elemental analysis, XRD measurement, and ionic conductivity measurement of the garnet-type lithium composite metal oxide powders obtained in Examples 5-1 and 5-2 are shown in Table 3. The ionic conductivity of the compacted powders of the garnet-type lithium composite metal oxide powders according to Examples 6-1 and 6-2 was 1.1 × 10 -5 S / cm and 1.9 × 10 -5 It was S / cm.

[0094] [Example 7] A composite metal oxide powder containing La and Zr according to Example 7 was obtained using the same procedure as in Example 1, except that the dried coprecipitate containing La, Zr, and Nb obtained in Example 4 was not heated at 500°C for 6 hours in an air atmosphere. XRD measurement confirmed that the composite metal oxide powder was amorphous, even though it had not been heat-treated. The XRD spectrum of the composite metal oxide powder obtained in Example 7 is also shown in Figure 2. The carbon content of the composite metal oxide powder was 1.1% by mass.

[0095] The manufacturing conditions for Example 7 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the amorphous composite metal oxide powder containing La and Zr obtained in Example 7 are shown in Table 2.

[0096] A lithium-containing composite metal oxide powder according to Example 7-1 was obtained using the same procedure as in Example 1-1, except that the amorphous composite metal oxide powder containing La and Zr obtained in Example 7 was used. As a result of XRD measurement, it was confirmed that the lithium-containing composite metal oxide powder was a single-phase garnet-type lithium composite metal oxide. The garnet-type lithium composite metal oxide powder obtained in Example 7-1 was subjected to elemental analysis, XRD measurement, and ionic conductivity measurement, and the results are shown in Table 3. The ionic conductivity of a compact of the garnet-type lithium composite metal oxide powder according to Example 7-1 was 1.0 × 10 -5 It was S / cm.

[0097] [Example 8] A composite metal oxide powder containing La and Zr according to Example 8 was obtained using the same procedure as in Example 4, except that the dried coprecipitate containing La, Zr, and Nb obtained in Example 4 was heated at 400°C for 6 hours in an air atmosphere. XRD measurement confirmed that the composite metal oxide powder was amorphous. The carbon content of the composite metal oxide powder was 1.1% by mass.

[0098] The manufacturing conditions for Example 8 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the amorphous composite metal oxide powder containing La and Zr obtained in Example 7 are shown in Table 2.

[0099] A lithium-containing composite metal oxide powder according to Example 8-1 was obtained using the same procedure as in Example 1-1, except that the amorphous composite metal oxide powder containing La and Zr obtained in Example 8 was used. XRD measurement results confirmed that the lithium-containing composite metal oxide powder was a single-phase garnet-type lithium composite metal oxide. The garnet-type lithium composite metal oxide powder obtained in Example 8-1 was subjected to elemental analysis, XRD measurement, and ionic conductivity measurement, and the results are shown in Table 3. The ionic conductivity of a compact of the garnet-type lithium composite metal oxide powder according to Example 8-1 was 2.5 × 10 -5 It was S / cm.

[0100] [Example 9] A composite metal oxide powder containing La and Zr according to Example 9 was obtained by the same procedure as in Example 4, except that the dried coprecipitate containing La, Zr, and Nb obtained in Example 4 was heated at 300°C for 6 hours in an air atmosphere. XRD measurement confirmed that the composite metal oxide powder was amorphous. The XRD spectrum of the composite metal oxide powder obtained in Example 9 is also shown in Figure 2. The carbon content of the composite metal oxide powder was 1.1% by mass.

[0101] The manufacturing conditions for Example 9 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the amorphous composite metal oxide powder containing La and Zr obtained in Example 9 are shown in Table 2.

[0102] A lithium-containing composite metal oxide powder according to Example 9-1 was obtained using the same procedure as in Example 1-1, except that the amorphous composite metal oxide powder containing La and Zr obtained in Example 9 was used. As a result of XRD measurement, it was confirmed that the lithium-containing composite metal oxide powder was a single-phase garnet-type lithium composite metal oxide. The garnet-type lithium composite metal oxide powder obtained in Example 9-1 was subjected to elemental analysis, XRD measurement, and ionic conductivity measurement, and the results are shown in Table 3. The ionic conductivity of a compact of the garnet-type lithium composite metal oxide powder according to Example 9-1 was 2.1 × 10 -5 It was S / cm.

[0103] [Example 10] A composite metal oxide powder containing La and Zr according to Example 10 was obtained by the same procedure as in Example 4, except that the dried coprecipitate containing La, Zr, and Nb obtained in Example 4 was heated at 200°C for 6 hours in an air atmosphere. XRD measurement confirmed that the composite metal oxide powder was amorphous. The XRD spectrum of the composite metal oxide powder obtained in Example 10 is also shown in Figure 2. The carbon content of the composite metal oxide powder was 1.3 mass%.

[0104] The manufacturing conditions for Example 10 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the amorphous composite metal oxide powder containing La and Zr obtained in Example 10 are shown in Table 2.

[0105] A lithium-containing composite metal oxide powder according to Example 10-1 was obtained using the same procedure as in Example 1-1, except that the amorphous composite metal oxide powder containing La and Zr obtained in Example 10 was used. As a result of XRD measurement, it was confirmed that the lithium-containing composite metal oxide powder was a single-phase garnet-type lithium composite metal oxide. The garnet-type lithium composite metal oxide powder obtained in Example 10-1 was subjected to elemental analysis, XRD measurement, and ionic conductivity measurement, and the results are shown in Table 3. The ionic conductivity of a compact of the garnet-type lithium composite metal oxide powder according to Example 10-1 was 1.3 × 10 -5 It was S / cm.

[0106] [Example 11] 780 g of pure water, 169.6 g of hydrous niobium oxide (Nb2O5·nH2O, Nb concentration: 76.4 mass%), and 87.76 g of 48 mass% NaOH aqueous solution were mechanically stirred at 70°C for 7 hours to solubilize the hydrous niobium oxide and obtain a clear aqueous solution. 31.8 g of a 35 mass% aqueous solution of peroxide was added to this aqueous solution, and the solution was washed with water by ultrafiltration to remove impurities such as Na ions, obtaining an aqueous solution of metal element M. A small amount of the obtained aqueous solution of metal element M was sampled and subjected to FT-IR measurement in the same manner as in Example 1, and the measured value was 850 cm -1 ±10cm -1 There is an absorption peak due to the Nb-O bond around 680 cm -1 ±20cm -1 An absorption peak due to the Nb-O-Nb bond was observed around , confirming that polyacid ions of Nb were produced in the aqueous solution containing metal element M. Figure 1 also shows the FT-IR spectrum of the aqueous solution containing Nb as metal element M obtained in this example.

[0107] Next, a slurry containing a coprecipitate of La, Zr, and Nb according to Example 7 was obtained using the same procedure as in Example 1, except that the molar ratio of the La, Zr, and Nb contents in the slurry was La:Zr:Nb=3:1.50:0.50. In this case, the pH of the slurry was 10.5. Furthermore, a composite metal oxide powder containing La and Zr according to Example 11 was obtained using the same procedure as in Example 1. XRD measurement confirmed that the composite metal oxide powder was amorphous. The carbon content of the composite metal oxide powder was 1.3 mass%.

[0108] The manufacturing conditions for Example 11 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the amorphous composite metal oxide powder containing La and Zr obtained in Example 11 are shown in Table 2.

[0109] A lithium-containing composite metal oxide powder according to Example 11-1 was obtained using the same procedure as in Example 1-1, except that the amorphous composite metal oxide powder containing La and Zr obtained in Example 11 was used. As a result of XRD measurement, it was confirmed that the lithium-containing composite metal oxide powder was a single-phase garnet-type lithium composite metal oxide. The garnet-type lithium composite metal oxide powder obtained in Example 11-1 was subjected to elemental analysis, XRD measurement, and ionic conductivity measurement, and the results are shown in Table 3. The ionic conductivity of a compact of the garnet-type lithium composite metal oxide powder according to Example 11-1 was 2.0 × 10 -5 It was S / cm.

[0110] [Comparative Example 1] 50.0 g of ammonium hydrogen carbonate was dissolved in 200 g of water, and 50.32 g of a niobium ammonium oxalate aqueous solution (Nb concentration: 5% by mass) was added to the resulting solution. Subsequently, while maintaining the temperature of the aqueous solution at 40°C, 84.19 g of a lanthanum nitrate aqueous solution (La concentration: 16% by mass) was added dropwise at a rate of 8.5 g / min to obtain a coprecipitate A of Nb and La. Subsequently, while maintaining the temperature at 40°C, 44.69 g of a zirconium ammonium carbonate aqueous solution (Zr concentration: 10% by mass) was added dropwise at a rate of 0.5 g / min to the obtained coprecipitate A to obtain a slurry containing coprecipitate B. The molar ratio of the contents of La, Zr and Nb in the obtained slurry was La:Zr:Nb=3:1.50:0.50.

[0111] Next, the pH was adjusted to a range of 9 to 11 using aqueous ammonia, and the mixture was heated at 90°C for 180 minutes. The resulting slurry containing coprecipitate B was subjected to suction filtration, and the residue was washed with pure water to remove moisture and separate coprecipitate B from the slurry. The resulting coprecipitate B was fired at 750°C for 5 hours to obtain a composite metal oxide powder containing La and Zr according to Comparative Example 1. XRD measurement of the composite metal oxide powder revealed that it was a crystalline powder with no halo pattern, in which ZrO2 peaks and unattributed peaks were observed in the 2θ:10° to 60° region. The carbon content of the composite metal oxide powder was 2.5% by mass.

[0112] The manufacturing conditions for Comparative Example 1 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the crystalline composite metal oxide powder obtained in Comparative Example 1 are shown in Table 2.

[0113] Next, lithium-containing composite metal oxide powders of Comparative Examples 1-1 and 1-2 were obtained using the same procedures as in Examples 1-1 and 1-2, except that the crystalline composite metal oxide powder obtained in Comparative Example 1 was used. XRD measurements were performed on the lithium-containing composite metal oxide powders obtained in Comparative Examples 1-1 and 1-2, and it was found that all of the lithium-containing composite metal oxide powders were multiphase garnet-type lithium composite metal oxides, in which a ZrO2 peak was observed in addition to the garnet-type crystal structure. The results of elemental analysis, XRD measurement, and ionic conductivity measurement were also performed on the garnet-type lithium composite metal oxide powders obtained in Comparative Examples 1-1 and 1-2. Table 3 shows the results. The ionic conductivity of the compacts of the garnet-type lithium composite metal oxide powders of Comparative Examples 1-1 and 1-2 was 4.4 × 10 -8 S / cm and 4.4 × 10 -8 It was S / cm.

[0114] The results of this comparative example show that a single-phase garnet-type lithium composite metal oxide cannot be obtained when a crystalline composite metal oxide powder containing La and Zr is used as a precursor. Furthermore, it is also found that if the composite metal oxide powder containing La and Zr has a high carbon content, the ionic conductivity of the final compact of the garnet-type lithium composite metal oxide powder decreases.

[0115] Comparative Example 2 A composite metal oxide powder containing La and Zr according to Comparative Example 2 was obtained by the same procedure as in Example 1, except that the dried coprecipitate containing La, Zr, and Ta obtained in Example 1 was heated at 800°C for 6 hours in an air atmosphere. XRD measurement of the composite metal oxide powder obtained in Comparative Example 2 revealed that the composite metal oxide powder was a crystalline powder in which peaks corresponding to a fluorite crystal structure were observed in the 2θ:10° to 60° region. The carbon content of the composite metal oxide powder was 0.3% by mass.

[0116] The XRD spectrum of the composite metal oxide powder obtained in Comparative Example 2 is also shown in Figure 2. The production conditions for Comparative Example 2 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement of the crystalline composite metal oxide powder obtained in Comparative Example 2 are also shown in Table 2.

[0117] Next, lithium-containing composite metal oxide powders of Comparative Examples 2-1 and 2-2 were obtained using the same procedures as in Examples 1-1 and 1-2, except that the crystalline composite metal oxide powder obtained in Comparative Example 2 was used. XRD measurements were performed on the lithium-containing composite metal oxide powders obtained in Comparative Examples 2-1 and 2-2. The lithium-containing composite metal oxide powders were all found to be multiphase garnet-type lithium composite metal oxides, with LaZrO peaks observed in addition to the garnet-type crystal structure. The garnet-type lithium composite metal oxide powders obtained in Comparative Examples 2-1 and 2-2 were subjected to elemental analysis, XRD measurement, and ionic conductivity measurement. The results are shown in Table 3. The ionic conductivity of the compacts of the garnet-type lithium composite metal oxide powders of Comparative Examples 2-1 and 2-2 was 4.4 × 10 -8 S / cm and 4.4 × 10 -8 It was S / cm.

[0118] The results of this comparative example show that a single-phase garnet-type lithium composite metal oxide cannot be obtained when a crystalline composite metal oxide powder containing La and Zr is used as a precursor. Furthermore, in this comparative example, even though the carbon content of the composite metal oxide powder containing La and Zr is low, the ionic conductivity of the final compact of the garnet-type lithium composite metal oxide powder is low.

[0119] Comparative Example 3 La(NO3)3·6H2O (Fujifilm Wako Pure Chemical Industries, Ltd.), ZrOCl2·8H2O (Fujifilm Wako Pure Chemical Industries, Ltd.), and TaCl5 (Fujifilm Wako Pure Chemical Industries, Ltd.) were weighed so that the molar ratio of La, Zr, and Ta content was La:Zr:Ta = 3:1.5:0.5, and dissolved in ethanol as a solvent. Citric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a chelating agent and ethylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a chelating polymerization agent were added to the solvent in which La, Zr, and Ta had been dissolved, and the mixture was heated at 140°C for 5 hours using a hot plate to esterify the chelating compound and ethylene glycol, yielding a gel. The resulting gel was baked at 350°C using a mantle heater, yielding a composite metal oxide powder containing La and Zr according to Comparative Example 3. The production conditions for this Comparative Example were in accordance with the production method of the Examples described in Patent Document 2.

[0120] When the powder obtained in Comparative Example 3 was subjected to XRD measurement, no clear diffraction peaks were observed in the XRD spectrum, and a halo was observed in the 2θ:10° to 60° region, indicating that the composite metal oxide powder was an amorphous powder. The carbon content of the composite metal oxide powder was 2.8 mass%.

[0121] The manufacturing conditions for Comparative Example 3 are shown in Table 1, and the results of elemental analysis, carbon content measurement, nitrogen content measurement, BET specific surface area measurement, and XRD measurement for the crystalline composite metal oxide powder obtained in Comparative Example 3 are shown in Table 2.

[0122] Next, lithium-containing composite metal oxide powders of Comparative Examples 3-1 and 3-2 were obtained using the same procedures as in Examples 1-1 and 1-2, except that the crystalline composite metal oxide powder obtained in Comparative Example 3 was used. XRD measurements were performed on the lithium-containing composite metal oxide powders obtained in Comparative Examples 3-1 and 3-2, and it was confirmed that each of the lithium-containing composite metal oxide powders was a single-phase garnet-type lithium composite metal oxide. The results of elemental analysis, XRD measurement, and ionic conductivity measurement were also performed on the garnet-type lithium composite metal oxide powders obtained in Comparative Examples 3-1 and 3-2. Table 3 shows the results. The ionic conductivity of the compacted powders of the garnet-type lithium composite metal oxide powders according to Comparative Examples 3-1 and 3-2 was 5.0 × 10 -6 S / cm and 1.8 × 10 -6 It was S / cm.

[0123] The results of this comparative example show that the composite metal oxide powder containing La and Zr is amorphous but has a high carbon content when the manufacturing method described in Patent Document 2 is used. Furthermore, it is clear that when this amorphous composite metal oxide powder containing La and Zr with a high carbon content is used as a precursor, a single-phase garnet-type lithium composite metal oxide can be obtained, but the ionic conductivity of the final compact of the garnet-type lithium composite metal oxide powder decreases.

[0124] From the above results, it was found that a single-phase garnet-type lithium composite metal oxide with high ionic conductivity can be obtained by using as a precursor an amorphous composite metal oxide powder containing 40% by mass or more and 62% by mass or less of La, 8% by mass or more and 26% by mass or less of Zr, 1% by mass or more and 20% by mass or less of a metal element M that can take any oxidation state from 3 to 6, a carbon content of 1.5% or less, and the remainder being oxygen and unavoidable impurities such as La and Zr, and mixing this with a Li compound and firing the resulting mixture.

[0125] When a crystalline composite metal oxide powder containing La and Zr is used as a precursor, the resulting garnet-type lithium composite metal oxide powder becomes multiphase and has reduced ionic conductivity. Furthermore, when an amorphous composite metal oxide powder containing La and Zr with a high carbon content is used as a precursor, the resulting garnet-type lithium composite metal oxide powder has a high carbon content and has reduced ionic conductivity.

[0126] [Table 1]

[0127] [Table 2]

[0128] [Table 3]

Claims

1. An amorphous composite metal oxide powder containing La and Zr, comprising 40% by mass or more and 62% by mass or less of La, 8% by mass or more and 26% by mass or less of Zr, and 1% by mass or more and 20% by mass or less of a metal element M, which is a metal element that can take any oxidation state of trivalent to hexavalent, excluding La and Zr, with a carbon content of 1.5% by mass or less, and the remainder being oxygen and unavoidable impurities.

2. 2. The amorphous composite metal oxide powder containing La and Zr according to claim 1, wherein the molar ratio of the contents of La, Zr, and the metal element M in the amorphous composite metal oxide powder is La:Zr:M=3:1.2-1.95:0.05-0.

8.

3. 2. The amorphous composite metal oxide powder containing La and Zr according to claim 1, wherein the metal element M can have a pentavalent oxidation state.

4. 2. The amorphous composite metal oxide powder containing La and Zr according to claim 1, wherein the metal element M is one or more of Ta, Nb, V and Sb.

5. The amorphous composite metal oxide powder containing La and Zr according to any one of claims 1 to 4, wherein the content of nitrogen as the inevitable impurity is 3 mass% or less.

6. 2. A method for producing an amorphous composite metal oxide powder containing La and Zr according to claim 1, obtaining a slurry containing a coprecipitate containing La, Zr, and a metal element M that can have any oxidation number from 3 to 6, excluding La and Zr; recovering the coprecipitate containing La, Zr, and the metal element M by solid-liquid separation from the slurry containing the coprecipitate containing La, Zr, and the metal element M; a step of heat-treating the recovered coprecipitate containing La, Zr, and the metal element M at a temperature of less than 800°C; A method for producing an amorphous composite metal oxide powder containing La and Zr, which has the following formula:

7. 7. The method for producing an amorphous composite metal oxide powder containing La and Zr according to claim 6, wherein the step of obtaining a slurry containing a coprecipitate containing La, Zr and the metal element M comprises simultaneously dissolving an inorganic La compound, an inorganic Zr compound and an inorganic metal element M compound in water.

8. 7. The method for producing an amorphous composite metal oxide powder containing La and Zr according to claim 6, wherein the step of obtaining a slurry containing a coprecipitate containing La, Zr, and the metal element M comprises the steps of: dissolving an inorganic La compound and an inorganic Zr compound in water to prepare an La-Zr-containing aqueous solution; dissolving an inorganic metal element M compound in water to prepare an aqueous solution containing the metal element M; and mixing the La-Zr-containing aqueous solution with the aqueous solution containing the metal element M.

9. 7. The method for producing an amorphous composite metal oxide powder containing La and Zr according to claim 6, wherein the heat treatment temperature in the heat treatment step is 700°C or less.

10. 7. The method for producing an amorphous composite metal oxide powder containing La and Zr according to claim 6, wherein the heat treatment temperature in the heat treatment step is 150°C or higher.

11. 8. The method for producing an amorphous composite metal oxide powder containing La and Zr according to claim 7, wherein the inorganic La compound, the inorganic Zr compound and the inorganic metal element M compound each do not contain carbon in their molecular structures.

12. 9. The method for producing an amorphous composite metal oxide powder containing La and Zr according to claim 8, wherein the inorganic La compound, the inorganic Zr compound and the inorganic metal element M compound each do not contain carbon in their molecular structures.

13. 9. The method for producing an amorphous composite metal oxide powder containing La and Zr according to claim 8, wherein the aqueous solution containing the metal element M contains an inorganic metal element M compound, ammonia water, and a peroxo complex of the metal element M produced by mixing hydrogen peroxide with water.

14. 7. The method for producing an amorphous composite metal oxide powder containing La and Zr according to claim 6, wherein the metal element M is one or more of Ta, Nb, V and Sb.

15. 7. The method for producing an amorphous composite metal oxide powder containing La and Zr according to claim 6, wherein the molar ratio of the contents of La, Zr, and the metal element M in the slurry containing the coprecipitate containing La, Zr, and the metal element M is La:Zr:M=3:1.2-1.95:0.05-0.

8.

16. The method for producing an amorphous composite metal oxide powder containing La and Zr according to any one of claims 6 to 15, wherein the coprecipitate containing La, Zr and the metal element M is washed when the slurry containing the coprecipitate containing La, Zr and the metal element M is subjected to solid-liquid separation.

17. A method for producing a garnet-type lithium composite metal oxide, comprising calcining a mixture of the amorphous composite metal oxide powder containing La and Zr according to claim 1 and a Li compound.

18. 18. The method for producing a garnet-type lithium composite metal oxide according to claim 17, wherein the mixture of the amorphous composite metal oxide powder containing La and Zr and the Li compound is fired at a temperature of 300°C or higher and lower than 700°C.

19. 18. The method for producing a garnet-type lithium composite metal oxide according to claim 17, wherein when the amorphous composite metal oxide powder containing La and Zr is mixed with the Li compound, the molar ratio of Li, La, Zr and the metal element M is Li:La:Zr:M=6.5-7.5:3:1.2-1.95:0.05-0.

8.

20. When manufacturing an all-solid-state battery having a battery unit structured such that a solid electrolyte layer is disposed between a positive electrode layer containing a positive electrode active material and a negative electrode layer containing a negative electrode active material, A method for producing an all-solid-state battery, wherein at least one of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer contains a garnet-type lithium composite metal oxide produced by the production method according to any one of claims 17 to 19.

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