KR20220024859A - Amorphous lithium ion conductive oxide powder and manufacturing method thereof, and manufacturing method of lithium ion conductive oxide powder having NASICON type crystal structure - Google Patents

Abstract

0.5 mass % or more and 6.5 mass % or less for lithium, more than 0 mass % to 25.0 mass % or less for aluminum, more than 0 mass % to 65.0 mass % or less for germanium, 10 mass % or more to 30 mass % or less for phosphorus, and more than 0 mass % to carbon. Provided is an amorphous lithium ion conductive oxide powder containing 0.35 mass% or less and having a specific surface area of 15 m 2 /g or more and 100 m 2 /g or less as measured by the BET one-point method.

Description

Amorphous lithium ion conductive oxide powder and manufacturing method thereof, and manufacturing method of lithium ion conductive oxide powder having NASICON type crystal structure

The present invention relates to an amorphous lithium ion conductive oxide powder, a method for producing the same, and a method for producing a lithium ion conductive oxide powder having a NASICON type crystal structure.

As a material of a solid electrolyte for an all-solid-state battery, there is a lithium ion conductor having a NASICON-type crystal structure with high ionic conductivity, and as one of them, the general formula Li _1+x Al _x Ge _2-x (PO ₄ ) ₃ (the range of x is, A lithium ion conductor (which may be described as "LAGP" in the present invention) described by 0 < x ≤ 1) is known.

In addition, the NASICON type|mold crystal structure is a crystal structure which takes space group R3c and has high lithium ion conductivity is known. Whether the measurement object has a NASICON-type crystal structure can be determined by powder X-ray diffraction measurement. For example, in the case of the LAGP described above, identification can be performed by performing verification with JCPDS card No. 01-080-1922.

In order to obtain high ionic conductivity, a method of crystallizing a lithium ion conductor having a NASICON type crystal structure after molding using LAGP in an amorphous state as in Patent Documents 1 and 2 is known.

The following methods are known as a manufacturing method of an amorphous LAGP.

1. A method for producing an amorphous LAGP by a sol-gel process using a metal alkoxide (see Patent Document 1).

2. A method of manufacturing an amorphous LAGP by a glass melting method (refer to paragraph (0018) of Patent Document 2).

Japanese Patent Laid-Open No. 2018-37341 Japanese Patent Laid-Open No. 2018-101467

However, according to the studies of the present inventors, even if a LAGP crystallized by producing a molded article using the amorphous LAGP manufactured by the method described in Patent Documents 1 and 2, and then calcining the molded article, the ionic conductivity is low. Therefore, in order to further improve the output of the all-solid-state battery, an amorphous lithium ion conductor that becomes a lithium ion conductor of a NASICON type crystal structure that exhibits higher ionic conductivity by calcining and crystallization is required. did.

In addition, in the firing step described in Patent Document 1, in order to increase the ionic conductivity, it is required to suppress the generation of GeO ₂ , which is a resistance component without ion conductivity, so that the firing step in an inert atmosphere is required, and the raw material cost and A way to increase production costs.

In addition, the glass melting method described in Patent Document 2 also includes a powder of a first LAGP having a particle diameter of 2.1 μm or more and 2.5 μm or less, and a powder of a second LAGP having a particle diameter of 0.18 μm or more and 0.25 μm or less in order to increase ion conductivity. This is a method that requires a kind of LAGP, which increases the cost of raw materials or production. In addition to this, melting of the raw material at a high temperature is essential, and lithium and germanium, which are elements that are easily volatilized, are volatilized during melting, and there is a problem that a compositional deviation occurs.

The present invention has been made under the circumstances described above, and the problem to be solved is a lithium ion conductive oxide powder having a NASICON type crystal structure that can be crystallized to obtain a lithium ion conductive oxide powder having a NASICON type crystal structure exhibiting high ionic conductivity. Amorphous lithium ion conductive oxide powder as a precursor, a manufacturing method for producing the amorphous lithium ion conductive oxide powder at low raw material cost and production cost, and a lithium ion conductive oxide powder having a NASICON type crystal structure that exhibits higher ionic conductivity To provide a manufacturing method.

In order to solve the above problems, an amorphous lithium ion conductive oxide powder containing a predetermined amount of elements such as lithium, aluminum, germanium, and phosphorus and obtained by making the carbon content and BET specific surface area of the powder within a predetermined range is crystallized It was discovered that it became lithium ion conductive oxide powder of a NASICON type|mold crystal structure, and exhibited high ionic conductivity.

Based on the above-mentioned knowledge, the present inventors, in addition to main constituent elements such as lithium, aluminum, germanium, and phosphorus, which are constituent elements of the amorphous lithium ion conductive oxide powder, have, if desired, aluminum as the main constituent element. A composition using an inorganic compound containing no carbon as a raw material containing elements such as phosphorus and silicon, which are elements to replace or germanium, and elements to be added as desired, and an aqueous solution of an inorganic compound containing the constituent elements Mixing, spray-drying the slurry containing the constituent elements of the lithium ion conductor by the co-precipitation method, and baking the mixture at 300°C or higher and 500°C or lower, solved the problem described above.

That is, the first invention for solving the above-mentioned problems is,

0.5 mass % or more and 6.5 mass % or less of lithium;

More than 0 mass % and 25.0 mass % or less of aluminum,

More than 0 mass % of germanium 65.0 mass % or less,

It contains 10 mass % or more and 30 mass % or less of phosphorus,

It is an amorphous lithium ion conductive oxide powder whose specific surface area measured by the BET one-point method is 15 m 2 /g or more and 100 m 2 /g or less.

The second invention is

1 mass % or more and 4 mass % or less of lithium;

More than 0 mass % and 6 mass % or less of aluminum,

It is the amorphous lithium ion conductive oxide powder of 1st invention containing more than 15 mass % and 35 mass % or less of germanium.

The third invention is

It is the amorphous lithium ion conductive oxide powder of 1st or 2nd invention which further contains 0.01 mass % or more and 0.35 mass % or less of carbon.

The fourth invention is

The amorphous lithium ion conductive oxide powder according to any one of the first to third inventions, wherein the specific surface area measured by the BET one-point method is 20 m 2 /g or more and 100 m 2 /g or less.

The fifth invention is

The amorphous lithium ion conductive oxide powder according to any one of the first to fourth inventions further containing at least one element selected from titanium, zirconium and hafnium.

The sixth invention is

It is the amorphous lithium ion conductive oxide powder in any one of 1st - 5th invention which further contains 10 mass % or less of silicon.

The seventh invention is

The amorphous lithium ion conductive oxide powder is represented by the formula of the general formula Li _1+x+w (Al _1-y M1 _y ) _x (Ge _1-z M2 _z ) _2-x P _3-w Si _w O ₁₂ , M1 is gallium , at least one selected from lanthanum, indium and yttrium, M2 is at least one selected from titanium, zirconium and hafnium, the range of x is 0 < x 1.0, the range of y is 0 y 1.0, and the range of z is The range of 0 z 1.0, w is 0 w 1.0, the amorphous lithium ion conducting oxide powder according to any one of the first to sixth inventions.

The eighth invention is

The amorphous lithium ion conductive oxide powder according to any one of the first to sixth inventions further containing at least one element selected from gallium, lanthanum, indium and yttrium.

The ninth invention is

A slurry forming step of mixing an aqueous solution of a lithium compound, an aqueous solution of an aluminum compound, an aqueous solution of a germanium compound, and an aqueous solution of an ammonium phosphate salt to obtain a suspension of a coprecipitate;

spray-drying the slurry to obtain a dried slurry;

It is a manufacturing method of an amorphous lithium ion conductive oxide powder which has a process of calcining the said slurry dried material at 300 or more and 500 or less.

The tenth invention is

In the slurry forming step, an aqueous solution of a compound further containing at least one element selected from gallium, lanthanum, indium and yttrium is mixed to obtain a suspension of a co-precipitate. Preparation of the amorphous lithium ion conducting oxide powder according to the ninth invention way.

The eleventh invention is

In the slurry forming step, an aqueous solution of a compound further containing at least one element selected from titanium, zirconium and hafnium is mixed to obtain a suspension of a co-precipitate of the amorphous lithium ion conducting oxide powder according to the ninth or tenth invention manufacturing method.

The twelfth invention is

A method for producing the amorphous lithium ion conductive oxide powder according to any one of the ninth to eleventh inventions, wherein in the slurry forming step, an aqueous solution of a silicon compound is further mixed to obtain a suspension of a coprecipitate.

The thirteenth invention is

Formation of the suspension in the slurry formation step is a method for producing the amorphous lithium ion conductive oxide powder according to any one of the ninth to twelfth inventions, wherein the aqueous solution of the germanium compound adjusted to pH 8 or higher is mixed.

The 14th invention is

A method for producing a lithium ion conductive oxide powder having a NASICON type crystal structure, comprising a step of calcining the amorphous lithium ion conductive oxide powder according to any one of claims 1 to 8 at a temperature higher than 500.

15th invention,

A slurry forming step of mixing an aqueous solution of a lithium compound, an aqueous solution of an aluminum compound, an aqueous solution of a germanium compound, and an aqueous solution of an ammonium phosphate salt to obtain a suspension of a coprecipitate;

spray-drying the slurry to obtain a dried slurry;

It is a method for producing a lithium ion conductive oxide powder having a NASICON-type crystal structure, comprising a step of calcining the dried slurry at a temperature higher than 500.

According to the present invention, an amorphous lithium ion conductive oxide powder which is a precursor of a lithium ion conductive oxide powder having a NASICON type crystal structure capable of obtaining a lithium ion conductive oxide powder having a NASICON type crystal structure exhibiting high ionic conductivity by crystallization, and the amorphous It is possible to provide a production method for producing a lithium ion conductive oxide powder with low raw material cost and production cost, and a production method for a lithium ion conductive oxide powder having a NASICON type crystal structure exhibiting higher ionic conductivity.

1 is a flowchart showing a manufacturing process of a lithium ion conductive oxide powder according to the present invention.
2 is an SEM photograph of 30,000 times the lithium ion conductive oxide powder according to Example 1 and Comparative Examples 1 and 2.
3 is an XRD spectrum of an amorphous lithium ion conducting oxide powder according to Example 1. FIG.
4 is an XRD spectrum of a lithium ion conductive oxide powder having a NASICON-type crystal structure according to Example 1. FIG.
5 is a flowchart illustrating a manufacturing process of a lithium ion conductive oxide powder according to Comparative Example 1. Referring to FIG.
6 is a flowchart illustrating a manufacturing process of a lithium ion conductive oxide powder according to Comparative Example 2. Referring to FIG.

The amorphous lithium ion conductive oxide powder according to the present invention is a precursor capable of obtaining a lithium ion conductive oxide powder having a NASICON type crystal structure by calcining and crystallizing it. The amorphous lithium ion conductive oxide powder according to the present invention and the lithium ion conductive oxide powder having a NASICON type crystal structure have, for example, the general formula Li _1+x+w (Al _1-y M1 _y ) _x (Ge _1-z M2 _z ) _2-x P _3-w Si _w O ₁₂ (provided that M1 is at least one selected from gallium, lanthanum, indium and yttrium, M2 is at least one selected from titanium, zirconium and hafnium, and the range of x is 0 < x ≤ 1.0, the range of y is 0 ≤ y ≤ 1.0, the range of z is 0 ≤ z ≤ 1.0, and the range of w is 0 ≤ w ≤ 1.0).

The amorphous lithium ion conductive oxide powder according to the present invention is molded into, for example, a pellet or a sheet, and then calcined to crystallize the molded product to form a lithium ion conductive oxide powder having a NASICON type crystal structure. A sintered body can be manufactured. The sintered body of the lithium ion conductive oxide powder having the NASICON type crystal structure is used as a solid electrolyte for an all-solid-state battery.

Hereinafter, with respect to the lithium ion conductive oxide powder according to the present invention, the manufacturing method thereof, and the manufacturing method of the lithium ion conductive oxide powder having a NASICON type crystal structure, [1] constituent elements, [2] BET specific surface area, [3] ] The manufacturing method will be described in order.

[1] constituent elements

The amorphous lithium ion conductive oxide powder according to the present invention has at least lithium, aluminum, germanium, and phosphorus as constituent elements. Lithium is an element which provides Li ⁺ carriers and brings about lithium ion conduction. Aluminum is a trivalent element added for the purpose of replacing germanium as a tetravalent metal element described later and increasing Li ⁺ carriers as charge compensation. Germanium is a tetravalent metal element required for a crystallized lithium ion conductive oxide powder to have a NASICON-type crystal structure, and phosphorus is a pentavalent metal element required for a crystallized lithium ion conductive oxide powder to have a NASICON-type crystal structure. is a metallic element.

In addition, a part of aluminum and germanium which are the above-mentioned constituent elements may be substituted with another element. Aluminum may be partially substituted by at least one element selected from gallium, lanthanum, indium, and yttrium. Germanium may be partially substituted with one or more elements selected from titanium, zirconium, and hafnium.

Phosphorus may be partially substituted with silicon. By substituting pentavalent phosphorus with tetravalent silicon, it becomes possible to increase Li ⁺ carriers, which can contribute to the improvement of Li ion conductivity.

Here, the content rate of a main constituent substance is demonstrated.

Lithium contains 0.5 mass % or more and 6.5 mass % or less as lithium element.

This is because lithium ion conductivity is ensured as content of lithium is 0.5 mass % or more. On the other hand, when content of lithium is 6.5 mass % or less and it crystallizes, it is because lithium ion conductive oxide powder turns into NASICON structure. The content of lithium is preferably 1.0 mass% or more, more preferably 1.5 mass% or more, still more preferably 1.8 mass% or more, and on the other hand, preferably 4.0 mass% or less, preferably 3.5 mass% or less, further Preferably it is 3.3 mass % or less.

Aluminum contains more than 0 mass % and 25.0 mass % or less as an aluminum element.

This is because the lithium ion conductivity in the lithium ion conductive oxide powder which has a NASICON type|mold crystal structure can be improved by adding aluminum.

When it crystallizes as content of aluminum is 25.0 mass % or less, lithium ion conductive oxide powder turns into NASICON type crystal structure. Content of aluminum becomes like this. Preferably it is 0.5 mass % or more, More preferably, it is 1.0 mass % or more, Preferably it is 6.0 mass % or less, On the other hand, More preferably, it is 5.5 mass % or less, More preferably, it is 5.0 mass % or less. am.

Germanium contains more than 0 mass % and 65.0 mass % or less as a germanium element.

When content of germanium exceeds 0 mass %, glass can be formed and it can be set as amorphous. On the other hand, if the content of germanium is 65.0 mass % or less, when crystallized, the lithium ion conductive oxide powder has a NASICON type crystal structure. The germanium content is preferably 15 mass% or more, more preferably 20 mass% or more, still more preferably 22 mass% or more, while preferably 35 mass% or less, more preferably 33 mass% or less, more Preferably it is 30 mass % or less.

In the amorphous lithium ion conductive oxide powder according to the present invention, phosphorus is contained in an amount of 10% by mass or more and 30% by mass or less as phosphorus element. In this case, glass can be formed to make it amorphous. On the other hand, when crystallized, the lithium ion conducting oxide powder has a NASICON type crystal structure. Phosphorus content becomes like this. Preferably it is 15 mass % or more, More preferably, it is 20 mass % or more, On the other hand, Preferably it is 28 mass % or less, More preferably, it is 25 mass % or less.

The content (mass %) of each element in the amorphous lithium ion conductive oxide powder according to the present invention described above is determined by preparing a solution in which the amorphous lithium ion conductive oxide powder is melted in alkali, and the luminescence analysis of this solution It is the value of the quantitative analysis result of each constituent element obtained by performing quantitative analysis of each constituent element using the apparatus (ICP-720 manufactured by Agilent).

In the amorphous lithium ion conductive oxide powder according to the present invention, the carbon content is preferably 0.35 mass% or less. When the carbon content is 0.35 mass % or less, it can be suppressed that the carbon is burned during sintering for crystallization and pores are generated in the portion, leading to deterioration of the ion conductivity. Amorphous lithium ion conductive oxide powder can make content of carbon into 0.01 mass % or more and 0.35 mass % or less, for example. Carbon content becomes like this. Preferably it is 0.3 mass % or less, More preferably, it is 0.25 mass % or less.

In addition, the measuring method of carbon content is demonstrated in an Example.

And, in the amorphous lithium ion conductive oxide powder according to the present invention, the sum of lithium element, aluminum element, germanium element, the above-mentioned substituted metal element, phosphorus element, carbon and oxygen added as desired is 90.0 mass% or more Although it will be 100.0 mass % or less, it is more preferable that it is 95.0 mass % or more. The remainder is impurities.

In addition, about the amount of oxygen in the amorphous lithium ion conductive oxide powder which concerns on this invention, each metal element and phosphorus mentioned above were an oxide, and it calculated from the amount of each metal element and phosphorus measured by ICP analysis. It is preferable that the amount of oxygen in amorphous lithium ion conductive oxide powder is 25-60 mass %. And about the amount of impurities, each amount of each metal element, phosphorus, carbon, and oxygen was deducted from 100 mass %, and was calculated|required.

Specific examples of the calculation are described in Examples.

Moreover, the amorphous lithium ion conductive oxide powder which concerns on this invention may further contain 10 mass % or less of silicon. By adding silicon, glass formation becomes easier. When the amount of silicon added exceeds 10% by mass, when crystallized, the lithium ion conductive oxide powder does not take the NASICON type crystal structure, which leads to deterioration of ionic conductivity as a result. Silicon content becomes like this. Preferably it is 5 mass % or less, More preferably, it is 3 mass % or less.

When the amorphous lithium ion conductive oxide powder according to the present invention contains silicon, the total of the lithium element, aluminum element, germanium element, phosphorus element, carbon, oxygen, and silicon atom contained is 90.0 mass% or more and 100.0 mass% or less However, it is more preferable that it is 95.0 mass % or more.

On the other hand, the amorphous lithium ion conductive oxide powder according to the present invention, in addition to lithium element, aluminum element, germanium element, the aforementioned substituted metal element, phosphorus element, carbon, and oxygen added as desired, is about 10% by mass, preferably It may contain about 3.0 mass % of impurities. The impurity is considered to be zirconia, which is a bead used in manufacturing the amorphous lithium ion conductive oxide powder, but if it is at this level, the lithium ion conduction characteristics when it becomes a lithium ion conductor having a NASICON type crystal structure, especially There is no adverse effect

[2] BET specific surface area

The amorphous lithium ion conductive oxide powder according to the present invention has a BET specific surface area of 15 m 2 /g or more and 100 m 2 /g or less. If it has a BET specific surface area of 15 m 2 /g or more and 100 m 2 /g or less, when the lithium ion conductive oxide powder is fired, heat is uniformly applied to the lithium ion conductor particles contained therein, and crystallization is uniform throughout the particles. This is because the ionic conductivity is improved. The BET specific surface area is preferably 20 m 2 /g or more, more preferably 22 m 2 /g or more, preferably 80 m 2 /g or less, and still more preferably 60 m 2 /g or less.

In addition, the specific measuring method of a BET specific surface area is demonstrated in an Example.

[3] Manufacturing method

An amorphous lithium ion conductive oxide powder according to the present invention, and a method for producing a lithium ion conductive oxide powder having a NASICON type crystal structure will be described.

In order to produce the amorphous lithium ion conductive oxide powder according to the present invention and the lithium ion conductive oxide powder having a NASICON type crystal structure, first, the raw materials containing each constituent element are completely dissolved in water to obtain an aqueous solution, The constituent elements are put into an ionic state. The aqueous solution of each constituent element is mixed, each constituent element is precipitated, and a slurry is obtained. After spray-drying the obtained slurry to make powder, the calcined product obtained by calcining is grind|pulverized. When making a precipitation produce|generate from the aqueous solution which each structural element melt|dissolved, you may mix previously with acidic solutions and alkaline solutions.

Hereinafter, with respect to the manufacturing method of the amorphous lithium ion conducting oxide powder and the lithium ion conducting oxide powder having a NASICON type crystal structure according to the present invention, FIG. 1 is a flowchart showing the manufacturing process of the amorphous lithium ion conducting oxide powder Referring to, (1) raw material aqueous solution preparation, (2) mixing, (3) spray treatment, (4) calcination, (5) grinding, (6) drying, (7) calcination, (8) NASICON-type crystal structure having a crystal structure The production of the lithium ion conductive oxide powder will be described in order.

(1) Preparation of raw material aqueous solution

A raw material containing lithium, aluminum, germanium, phosphorus, which are constituent elements of the lithium ion conductive oxide powder according to the present invention, and, if necessary, substitution elements of aluminum and germanium, and each element of phosphorus and silicon, which are additive elements, are dissolved in water, respectively. Dissolve completely to make an aqueous solution. In that case, as long as it is a water-soluble salt which does not contain carbon as a raw material, or an element which melt|dissolves by liquid, you may add acid or alkali to the oxide of each element, and may dissolve it.

On the other hand, when a carbon-containing raw material, for example, acetate or organic acid salt of each element is used, the carbon may remain in the lithium ion conductive oxide powder according to the present invention. From the above viewpoint, the raw material containing each constituent element is preferably an inorganic compound.

From the above, Table 1 shows examples of the raw material compounds of each element suitable for preparation of the raw material aqueous solution. At this time, in Table 1, if the pH of the aqueous solution after dissolution is acidic, you may mix the said acidic raw material aqueous solution. Further, another raw material powder may be added to the acidic raw material aqueous solution and dissolved. The same is true in the case of alkaline raw material aqueous solutions.

For example, when the raw material compound is germanium dioxide, an aqueous solution of germanium can be prepared by adding germanium dioxide to pure water and stirring while adding an alkali. At this time, it is not necessary to examine the temperature in particular at the time of melt|dissolution, and heating may or may not be necessary. This is because germanium dioxide dissolves in the pH value of the aqueous solution in the range of about 8 to 12.

When using a raw material compound that is not water-soluble, although the liquidity of the solution is adjusted, it is preferable to use ammonia in which no impurities remain as the alkali. As an acid, nitric acid, sulfuric acid, hydrochloric acid, etc. can be used. Moreover, as an alkali, lithium hydroxide aqueous solution can also be used. In that case, it goes without saying that the lithium hydroxide is also weighed and used as a raw material compound for lithium.

[Table 1]

(2) mixing (slurrying)

This is a step of mixing the raw material aqueous solution prepared in the above (1) according to the target composition of the lithium ion conductive oxide powder, and obtaining a slurry containing the constituent elements of the lithium ion conductor by a coprecipitation method. For example, if an acidic aqueous solution in which lithium nitrate, aluminum nitrate 9hydrate, and ammonium dihydrogen phosphate is dissolved is added to an alkaline aqueous germanium solution dissolved with ammonia, it immediately becomes turbid, and lithium, aluminum, germanium, A slurry containing phosphorus or the like can be obtained. In this mixing process, it is not necessary to examine in particular the liquid temperature, and it may or may not need to heat. It is thought that the constituent element which precipitated as a hydroxide and the constituent element which existed as an ion exist in the said slurry. Moreover, in order to reduce the carbon content derived from carbonic acid in a slurry, it is also a preferable structure to nitrogen-purify the said slurry.

In the present invention, the raw material aqueous solution is mixed to obtain a slurry containing the constituent elements of the lithium ion conductor by the co-precipitation method. ) is because it realizes a supersaturated state that is higher than the solubility product. By realizing the above-mentioned supersaturation state, the number of nuclei of the generated precipitate increases. As a result, the particle size of the precipitated precipitate becomes small, and finally, the effect of increasing the BET specific surface area of the particles of the amorphous lithium ion conductor is obtained. because you can get Further, in the co-precipitation method of the present invention, it is considered that not all of the constituent elements of the lithium ion conductor are precipitated, but most constituent elements are co-precipitated, and the constituent elements in the particles of the amorphous lithium ion conductor are The effect of improving uniformity can also be acquired.

On the other hand, when it is decided to dehydrate from the raw material aqueous solution in which the constituent elements are completely dissolved, the precipitation due to the change in solubility does not pass through a sudden supersaturation state due to the pH change as in the co-precipitation method described above. As a result, the number of nuclei of the precipitate to be formed decreases, and the particle size of the precipitate to be precipitated increases. In addition, since solubility differs depending on the constituent elements, in the process of dehydration, constituent elements with low solubility are precipitated first, and constituent elements with high solubility are precipitated later.

(3) spray drying

It is a process of spray-drying the slurry obtained in said (2) using a spray dryer etc., evaporating the water|moisture content in the said slurry, and obtaining powder.

Here, in providing the drying step, in the slurry obtained in the above (2), lithium, aluminum, germanium, phosphorus, which are constituent elements, and most of the above-mentioned substituted metal elements added as desired are co-precipitated, but present as ions Because there are things you are doing. For example, it is considered that a lithium ion conductor having a planned composition cannot be obtained by using the powder recovered from the slurry by the filtration process.

On the other hand, it is also possible to obtain powder from the obtained slurry by evaporation to dryness using a hot plate etc. instead of spray drying. However, when the time for dehydration is long, there is a fear that the constituent elements are non-uniformly precipitated due to the difference in solubility between constituent elements present as ions in the slurry.

Here, by performing dehydration as quickly as possible, the non-uniformity of precipitation resulting from the difference in solubility between constituent elements can be reduced. Therefore, it is thought that the spray-drying method has an effect on the composition uniformity of the particles rather than a method such as evaporation to dryness. Moreover, the spray-drying method which can remove a solvent in a short time also from a viewpoint of a production is preferable.

By spray-drying, although the element contained in a slurry remains in a dry powder, an excess impurity can be volatilized by heat and can be removed by baking the obtained dry powder. Moreover, in order to remove an impurity, you may add the process of washing dry powder with water to remove an impurity, and drying.

(4) firing

The powder obtained in (3) is calcined, and ammonia or nitric acid components derived from the raw material remaining in the powder are removed to obtain an amorphous lithium ion conductive oxide powder, or via the amorphous lithium ion conductive oxide powder It is a process of obtaining lithium ion conductive oxide powder having a NASICON type crystal structure without any work. Hereinafter, (I) the case of obtaining an amorphous lithium ion conductive oxide powder and (II) the case and process of obtaining the lithium ion conducting oxide powder which has a NASICON type crystal structure are demonstrated.

(I) When obtaining amorphous lithium ion conductive oxide powder

As described above, by compacting and firing the amorphous lithium ion conductor powder, a dense compact is obtained, but impurities such as ammonia and nitric acid are present in the amorphous lithium ion conductive oxide powder, and the impurities are contained. When it is fired, impurities are burned or volatilized, so that pores may be formed in the portion and dense pellets may not be obtained. Therefore, the amorphous lithium ion conductive oxide powder is fired at a temperature of 500° C. or less.

Specifically, the amorphous lithium ion conductor powder obtained in (3) is put into a container such as an alumina product, and the temperature is raised from room temperature to 300°C to 500°C at a temperature increase rate of 0.1 to 20°C/min. By baking at 300 degreeC or more, removal of ammonia, a nitric acid component, etc. becomes easy. On the other hand, it is because crystallization of a lithium ion conductor can be avoided by setting it as 500 degrees C or less.

And after reaching 300 degreeC - 500 degreeC, an amorphous lithium ion conductive oxide powder is obtained by baking for 60 to 180 minutes. The firing atmosphere is not limited to the atmospheric atmosphere and may be a nitrogen atmosphere, but from the viewpoint of cost and productivity, the atmospheric atmosphere is preferable, and the nitrogen atmosphere is preferable from the viewpoint of suppressing the production of lithium carbonate.

(II) When obtaining lithium ion conductive oxide powder having a NASICON type crystal structure

Specifically, as described above, in a container such as an alumina product, put the amorphous lithium ion conductive oxide powder obtained in (3) above, in order to obtain a lithium ion conductive oxide powder having a NASICON type crystal structure, exceeding 500 ° C., Preferably, the lithium ion conductive oxide powder having a NASICON type crystal structure is obtained by calcining and crystallizing at a temperature of 550°C or higher and 900°C or lower. Although a temperature increase rate in particular does not ask, 1-20 degreeC/min is preferable. Although there is no restriction|limiting in particular in the firing atmosphere, It is preferable to set it as atmospheric atmosphere. Although baking time in particular does not matter, it is preferable to set it as 30 minutes or more and 300 minutes or less after reaching more than 500 degreeC and 900 degrees C or less.

(5) crushing

This is a step of pulverizing the amorphous lithium ion conductive oxide powder obtained in (4) to a particle size determined in a later step. The particle diameter of the amorphous lithium ion conductive oxide powder does not affect the ionic conductivity. However, for example, when forming the lithium ion conductive oxide powder into a sheet shape, it is not preferable that particles having a thickness greater than the desired sheet thickness exist, and it is necessary to adjust the particle size. Although a known method can be used as a grinding|pulverization method, wet grinding using a bead mill etc. is preferable. When wet grinding is performed, solid-liquid separation is performed after the treatment to dry the lithium ion conductive oxide powder. For example, a preferable particle diameter of the amorphous lithium ion conductive oxide powder is 1 µm to 5 µm in terms of a cumulative 50% particle diameter (D ₅₀ ) on a volume basis.

As a solvent at the time of wet grinding, an organic solvent is preferable, and IPA is specifically preferable. This is because IPA does not remain in the lithium ion conductive oxide powder since it volatilizes by drying after pulverization.

When the solvent is water, lithium ion exchanges with protons, which may lead to deterioration of lithium ion conductivity.

Moreover, when using a bead mill for grinding|pulverization, as a bead, a zirconia bead is preferable.

By passing the above steps (1) to (5), the amorphous lithium ion conductive oxide powder according to the present invention can be obtained.

(6) drying

When the amorphous lithium ion conductive oxide powder is wet-pulverized in the step (5), thereafter, solid-liquid separation such as filtration is performed, the temperature equal to or higher than the boiling point of the solvent used, and the step (4) above The lithium ion conductive oxide powder according to the present invention can be obtained by drying in a temperature range below the calcination temperature performed in , and removing the used solvent.

However, when dry grinding is performed on the lithium ion conductive oxide powder in the step (5), the lithium ion conductive oxide powder according to the present invention can be obtained even if the drying step is omitted.

Whether the lithium ion conductive oxide powder is amorphous can be confirmed by powder X-ray diffraction (XRD) measurement by observing a halo in a region of 2θ: 15° to 40°. In addition, a "halo" is a gentle undulation of the intensity of an X-ray, and it is observed as a broad rise in an X-ray chart. And, the half width of the halo is 2θ: 2° or more.

(7) firing

The lithium ion conductive oxide powder having a NASICON type crystal structure can be produced by calcining and crystallizing the amorphous lithium ion conductive oxide powder obtained in (6) above.

As a calcination temperature, it is more than 500 degreeC, Preferably it is 550 degreeC or more and 900 degrees C or less.

Although there is no restriction|limiting in particular in the baking atmosphere, It is preferable to set it as atmospheric atmosphere.

Although baking time in particular does not matter, it is preferable to set it as 30 minutes or more and 300 minutes or less after reaching more than 500 degreeC and 900 degrees C or less.

(8) Lithium ion conducting oxide powder having a NASICON type crystal structure

The lithium ion conductive oxide powder having a NASICON-type crystal structure can be produced by the process described above.

The lithium ion conductive oxide powder having a NASICON type crystal structure contains the same elements as those contained in the above-mentioned amorphous lithium ion conductive oxide powder before crystallization.

The lithium ion conductor of the NASICON type crystal structure of the present invention was measured using an XRD apparatus to obtain an XRD profile. A crystal structure can be identified by comparing the obtained XRD profile with JCPDS card No.01-080-1922 using the electronic calculator attached to the XRD apparatus.

Example

(Example 1)

An amorphous lithium ion conductive oxide powder according to Example 1 was prepared according to the flow showing the manufacturing process of the amorphous lithium ion conductive oxide powder described above. And analysis and characteristic evaluation of the amorphous lithium ion conductive oxide powder according to Example 1 were performed.

(1) Preparation of raw material aqueous solution

In Example 1, (I) germanium aqueous solution: alkalinity and (II) lithium, aluminum, phosphorus containing aqueous solution: acidity were prepared as raw material aqueous solution. Hereinafter, each is demonstrated.

(Ⅰ) Germanium aqueous solution

192.5 g of germanium dioxide was added to 4000 g of pure water, it was heated to 40° C. while stirring, and 97.5 g of ammonia water having a concentration of 28% by mass as an alkali was further added to dissolve the germanium oxide to prepare a germanium aqueous solution. The pH value in the prepared aqueous solution was 10.7 and was alkaline.

(Ⅱ) Aqueous solution containing lithium, aluminum and phosphorus

To 150 g of pure water, 21.7 g of lithium nitrate, 39.4 g of aluminum nitrate 9hydrate, and 72.5 g of ammonium dihydrogen phosphate were added to prepare an aqueous solution containing lithium, aluminum and phosphorus. The pH value in the prepared lithium, aluminum, and phosphorus containing aqueous solution was 1.4, and it was acidic.

(2) mixing (slurrying)

720 g of the alkaline germanium aqueous solution was aliquoted and heated to 40° C. while stirring, and the entire amount (283.7 g) of the acidic lithium, aluminum, and phosphorus-containing aqueous solution was added thereto, and the aqueous solution was prepared immediately after the addition. It became cloudy to obtain a white slurry. The pH value of the obtained white slurry was 4.3.

(3) spray drying

The white slurry was spray-dried using a spray dryer (SD-1000 manufactured by TOKYO RIKAKIKAI CO, LTD.), and the water in the white slurry was evaporated to form a solid phase at once to obtain a white powder. Moreover, as conditions of spray drying, it was set as the inlet temperature of 180 degreeC, the outlet temperature of 90 degreeC, and 10 g/min of the addition rate of the said white slurry.

(4) firing

Amorphous lithium ion conduction by putting the white powder obtained by the spray drying into an alumina container, raising the temperature from room temperature to 400°C at a temperature increase rate of 5°C/min, reaching 400°C, and then calcining in an atmospheric atmosphere for 120 minutes An oxide powder was obtained.

2 (Example 1) shows an SEM photograph of 30,000 times the obtained amorphous lithium ion conductive oxide powder.

(5) wet grinding

40 g of the amorphous lithium ion conductive oxide powder was loaded into a bead mill together with 160 g of φ1 mm Zr beads and 94.32 g of IPA, and wet-pulverized for 120 minutes to adjust the particle size, thereby adjusting the particle size. An ion conducting oxide powder was obtained.

(6) drying

The amorphous lithium ion conductive oxide powder having the adjusted particle size was placed in a dryer, dried at 100° C. for 3 hours, and IPA was removed to obtain an amorphous lithium ion conductive oxide powder according to Example 1.

The cumulative 50% particle diameter (D ₅₀ ) of the amorphous lithium ion conductive oxide powder according to Example 1 by volume was 1.8 µm as measured by Helos (dispersion pressure 5 bar). These values are shown in Table 3.

(7) amorphous lithium ion conducting oxide powder

For the obtained amorphous lithium ion conductive oxide powder, (I) composition analysis, (II) carbon amount analysis, (III) oxygen amount calculation, (IV) BET specific surface area measurement, (V) XRD measurement of amorphous lithium ion conductive oxide powder, (VI) Ion conductivity evaluation and (VII) XRD measurement of the green compact of the lithium ion conductor were performed. Hereinafter, each method and result will be described.

(Ⅰ) Composition analysis

The amorphous lithium ion conductive oxide powder according to Example 1 was dissolved in alkali using sodium carbonate as a melting agent. Then, elemental analysis was performed on this solution using an ICP apparatus (ICP-720 manufactured by Agilent), lithium: 2.43 mass%, aluminum: 3.02 mass%, germanium: 25.1 mass%, and phosphorus: 21.7 mass% got it Table 2 shows the analysis values of each constituent element.

(Ⅱ) Carbon Amount Analysis

The amount of carbon in the amorphous lithium ion conductive oxide powder according to Example 1 was measured using a trace carbon and sulfur analyzer (EMIA-U510 manufactured by HORIBA, Ltd.), and was found to be 0.16 mass %. These values are shown in Table 2.

(Ⅲ) Calculation of the amount of oxygen

The amount of oxygen in the amorphous lithium ion conductive oxide powder was calculated as follows.

Since the oxide of monovalent lithium is Li ₂ O, the amount of oxygen corresponding to the lithium oxide is expressed by the following formula.

Oxygen amount according to lithium oxide = (Li concentration × (food of Li ₂ O/number of Li atoms in Li ₂ O) ÷ food of Li) — Li concentration… (ceremony)

On the other hand, from the above-mentioned (I), the analysis result of ICP of lithium concentration is 2.43 mass %,

Oxygen amount according to lithium oxide = (2.43 × (29.88/2) ÷ 6.94) - 2.43 = 2.80 mass%

becomes

Since the oxide of trivalent aluminum is Al ₂ O ₃ , the amount of oxygen corresponding to the aluminum oxide is expressed by the following formula.

Oxygen amount according to aluminum oxide = (Al concentration × (food of Al ₂ O ₃ / number of Al atoms in Al ₂ O ₃ ) ÷ food of Al) — Al concentration… (ceremony)

On the other hand, since the analysis result of ICP of aluminum concentration is 3.02 mass %,

Oxygen amount according to aluminum oxide = (3.02 × (101.96/2) ÷ 26.98) - 3.02 = 2.69 mass%

becomes

Since the oxide of tetravalent germanium is GeO ₂ , the amount of oxygen according to the germanium oxide is expressed by the following formula.

Oxygen amount according to germanium oxide = (Ge concentration × (GeO ₂ food/Number of Ge atoms in GeO ₂ ÷ Ge food) ― Ge concentration … (ceremony)

On the other hand, since the analysis result of ICP of germanium concentration is 25.1 mass %,

Oxygen amount according to germanium oxide = (25.1 × (104.61/1) ÷ 72.61) - 25.1 = 11.06 mass%

becomes

Since the oxide of pentavalent phosphorus is P ₂ O ₅ , the amount of oxygen corresponding to the phosphorus oxide is expressed by the following formula.

Oxygen amount according to phosphorus oxide = (P concentration × (food in P ₂ O ₅ / number of P atoms in P ₂ O ₅ ) ÷ food in P) ― P concentration … (ceremony)

On the other hand, since the analysis result of ICP of phosphorus concentration is 21.7 mass %,

Oxygen amount according to phosphorus oxide = (21.7 × (141.94/2) ÷ 30.97) - 21.7 = 28.02 mass%

becomes

From the above calculation result, when the amount of oxygen corresponding to each metal element oxide and phosphorus oxide was summed up, it became 2.80+2.69+11.06+28.02=44.6 mass %. These values are shown in Table 2.

The obtained amorphous lithium ion conductive oxide powder was Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ .

In addition, the amount of impurities was calculated as 3.0 mass % from each amount of the above-mentioned metallic element, phosphorus, carbon, and oxygen. These values are shown in Table 2.

(IV) BET specific surface area measurement

The BET specific surface area of the amorphous lithium ion conductive oxide powder according to Example 1 was measured using a BET specific surface area measuring instrument (Macsorb manufactured by MOUNTECH Co., Ltd.). After degassing by flowing nitrogen gas at 105° C. for 20 minutes into the measuring device, a mixed gas of nitrogen and helium (N2: 30 vol%, He: 70 vol%) was flowed, and the amorphous lithium ion conductive oxide powder according to Example 1 The BET specific surface area of was 27.7 m 2 /g as measured by the BET one-point method. These values are shown in Table 3.

(V) XRD measurement of amorphous lithium ion conducting oxide powder

XRD measurement was performed on the amorphous lithium ion conducting oxide powder according to Example 1. The measurement conditions are shown in Table 4, and the obtained XRD spectrum is shown in FIG.

From FIG. 3, it was confirmed that the lithium ion conductor according to Example 1 had an amorphous structure. Table 3 shows this point. This is because the halo was observed in the region of 2θ: 15° to 40° by XRD measurement. In addition, a "halo" is a gentle undulation of the intensity|strength of an X-ray, and it observes as a broad rise in an X-ray chart.

In addition, the half width of the halo was 2θ: 2° or more.

(VI) Ionic conductivity evaluation

0.5 g of the amorphous lithium ion conductive oxide powder according to Example 1 was put into a cylindrical insulated container with a diameter of 10 mm, and was pressed together with a stainless steel current collector at 360 MPa by a press to obtain a green compact.

The green compact of the obtained amorphous lithium ion conductive oxide powder was calcined for 120 minutes after the furnace temperature reached 700° C., and crystallized to crystallize the lithium ion conductive oxide powder (Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ ) of a green compact was prepared.

For the green compact of lithium ion conductive oxide powder having a NASICON type crystal structure produced by the above firing, in an atmospheric atmosphere, at a temperature of 25° C., a potentio/galvanostat (1470E manufactured by Solartron) and a frequency response analyzer ( 1255B manufactured by Solartron) was used, and measurement was performed in the range of 100 Hz to 4 MHz by the AC impedance method. Then, from the Cole-Cole plot (complex impedance planar plot) of the measured values, the resistance value of the green compact having the NASICON type crystal structure was obtained, and from the obtained resistance value, an amorphous lithium ion conductive oxide powder was crystallized. Lithium having a NASICON type crystal structure The ion conductivity of the ion conductive oxide powder was calculated to be 6.4 × 10 ^-5 S/cm. These values are shown in Table 3.

(VII) XRD measurement of green compacts of lithium ion conductors

The green compact of lithium ion conductor crystallized by baking at 700°C for 120 minutes was subjected to XRD measurement under the conditions described in “(V) XRD measurement of amorphous lithium ion conductive oxide powder”, JCPDS Card No.01-080- In contrast to 1922, the crystal peak of LAGP, which is a lithium ion conductor having a NASICON type crystal structure, was observed, and the green compact of the lithium ion conductive oxide powder according to Example 1 was a lithium ion conductor having a NASICON type crystal structure. Could know. The obtained XRD spectrum is shown in FIG.

(Examples 2 to 8)

The same operation as in Example 1 was carried out, except that the steps of “(1) Preparation of raw material aqueous solution” and “(2) Mixing (slurrying)” described in Example 1 were changed as described later. Amorphous lithium ion conducting oxide powders according to 2 to 8 were prepared.

And, using the prepared amorphous lithium ion conductive oxide powder according to Examples 2 to 8, described in “(7) Amorphous lithium ion conductive oxide powder” of Example 1, “(I) composition analysis, (II) charcoal Small volume analysis, (III) oxygen content analysis, (IV) BET specific surface area measurement, (V) XRD measurement of amorphous lithium ion conductive oxide powder, (VI) ion conductivity evaluation, (VII) XRD measurement of green compact of lithium ion conductor ' was carried out.

As a result of composition analysis of each constituent element in the amorphous lithium ion conducting oxide powder according to Examples 2 to 8, the amount of oxygen, carbon amount, and impurity amount are shown in Table 2, and the cumulative 50% particle diameter (D ₅₀ ) by volume Table 3 shows the values measured by Helos (dispersion pressure 5 bar), the crystalline phase, and the BET specific surface area. And, Table 3 shows the ionic conductivity of the lithium ion conductive oxide powder having a NASICON type crystal structure according to Examples 2 to 8.

In addition, the calculation method of the amount of oxygen according to Ti, Zr, and Si contained in the amorphous lithium ion conductive oxide powder concerning Examples 5-7 is demonstrated in each Example. Moreover, also in Examples 5-7, the calculation method of the oxygen amount according to elements other than Ti, Zr, and Si is the same as that of Example 1.

<Example 2> (1) Preparation of raw material aqueous solution

(Ⅰ) Germanium aqueous solution

192.5 g of germanium dioxide was added to 4000 g of pure water, it was heated to 40°C while stirring, and 97.5 g of ammonia water having a concentration of 28% by mass as an alkali was further added to dissolve the germanium dioxide to prepare an aqueous germanium solution. The pH value in the prepared aqueous solution was 10.7, and was alkaline.

(Ⅱ) Aqueous solution containing lithium, aluminum and phosphorus

To 150 g of pure water, 18.8 g of lithium nitrate, 23.6 g of aluminum nitrate 9hydrate, and 72.5 g of ammonium dihydrogen phosphate were added to prepare an aqueous solution containing lithium, aluminum and phosphorus. The pH value in the prepared lithium, aluminum, and phosphorus containing aqueous solution was 1.5, and it was acidic.

(2) mixing (slurrying)

816 g of the alkaline germanium aqueous solution was aliquoted and heated to 40° C. while stirring, and the entire amount of the acidic lithium, aluminum, phosphorus, and titanium-containing aqueous solution was added thereto. got it The pH value of the obtained white slurry was 6.7.

(3) amorphous lithium ion conducting oxide powder

Using the obtained white slurry, it operated similarly to Example 1, and the amorphous lithium ion conducting oxide powder which concerns on Example 2 was obtained. The composition formula of the obtained amorphous lithium ion conductive oxide powder was Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ .

Using the amorphous lithium ion conductor powder according to Example 2, XRD measurement was performed in the same manner as in Example 1, and a halo was observed in the region of 2θ: 15° to 40°, and the half width of the halo was 2θ: 2° It was more than that.

Using the amorphous lithium ion conductor powder according to Example 2, in the same manner as in Example 1, a lithium ion conductive oxide powder according to Example 2 was obtained, and a green compact of a lithium ion conductor was obtained.

Using the green compact of the lithium ion conductor according to Example 2, XRD measurement was performed in the same manner as in Example 1, and the lithium ion conductive oxide powder according to Example 2 was a lithium ion conductive oxide having a NASICON type crystal structure. It was found to be a powder (composition formula: Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ ).

<Example 3> (1) Preparation of raw material aqueous solution

(Ⅰ) Germanium aqueous solution

192.5 g of germanium dioxide was added to 4000 g of pure water, it was heated to 40°C while stirring, and 97.5 g of ammonia water having a concentration of 28% by mass as an alkali was further added to dissolve the germanium dioxide to prepare an aqueous germanium solution. The pH value in the prepared aqueous solution was 10.7 and was alkaline.

(Ⅱ) Aqueous solution containing lithium, aluminum and phosphorus

To 150 g of pure water, lithium nitrate 22.7 g, aluminum nitrate 9 hydrate 23.6 g, and ammonium dihydrogen phosphate 72.5 g were added to prepare an aqueous solution containing lithium, aluminum and phosphorus. The pH value in the prepared lithium, aluminum, and phosphorus containing aqueous solution was 1.4, and it was acidic.

(2) mixing (slurrying)

816 g of the alkaline germanium aqueous solution was aliquoted and heated to 40° C. while stirring, and the entire amount of the acidic lithium, aluminum, phosphorus, and titanium-containing aqueous solution was added thereto. got it The pH value of the obtained white slurry was 4.1.

(3) amorphous lithium ion conducting oxide powder

Using the obtained white slurry, it operated similarly to Example 1, and the amorphous lithium ion conducting oxide powder which concerns on Example 3 was obtained. The composition formula of the obtained amorphous lithium ion conductive oxide powder was Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ .

Using the amorphous lithium ion conductor powder according to Example 3, XRD measurement was performed in the same manner as in Example 1, and halos were observed in the region of 2θ: 15° to 40°, and the half width of the halo was 2θ: 2° It was more than that.

Using the amorphous lithium ion conductor powder according to Example 3, in the same manner as in Example 1, a lithium ion conductive oxide powder according to Example 3 was obtained, and a green compact of a lithium ion conductor was obtained.

Using the green compact of the lithium ion conductor according to Example 3, XRD measurement was performed in the same manner as in Example 1, and the lithium ion conductive oxide powder according to Example 3 was a lithium ion conductive oxide having a NASICON type crystal structure. It was found to be a powder (composition formula: Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ ).

<Example 4> (1) Preparation of raw material aqueous solution

(Ⅰ) Germanium aqueous solution

192.5 g of germanium dioxide was added to 4000 g of pure water, it was heated to 40°C while stirring, and 97.5 g of ammonia water having a concentration of 28% by mass as an alkali was further added to dissolve the germanium dioxide to prepare an aqueous germanium solution. The pH value in the prepared aqueous solution was 10.7 and was alkaline.

(Ⅱ) Aqueous solution containing lithium, aluminum and phosphorus

To 150 g of pure water, 24.8 g of lithium nitrate, 57.9 g of aluminum nitrate 9hydrate, and 72.5 g of ammonium dihydrogen phosphate were added to prepare an aqueous solution containing lithium, aluminum and phosphorus. The pH value in the prepared lithium, aluminum, and phosphorus containing aqueous solution was 1.3, and it was acidic.

(2) mixing (slurrying)

600 g of the alkaline germanium aqueous solution was aliquoted and heated to 40° C. while stirring, and the entire amount of the acidic lithium, aluminum, phosphorus, and titanium-containing aqueous solution was added thereto. got it The pH value of the obtained white slurry was 3.9.

(3) amorphous lithium ion conducting oxide powder

Using the obtained white slurry, it operated similarly to Example 1, and the amorphous lithium ion conducting oxide powder which concerns on Example 4 was obtained. The composition formula of the obtained amorphous lithium ion conductive oxide powder was Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ .

Using the amorphous lithium ion conductor powder according to Example 4, XRD measurement was performed in the same manner as in Example 1, and halos were observed in the region of 2θ: 15° to 40°, and the half width of the halo was 2θ: 2° It was more than that.

Using the amorphous lithium ion conductor powder according to Example 4, in the same manner as in Example 1, a lithium ion conductive oxide powder according to Example 4 was obtained, and a green compact of a lithium ion conductor was obtained.

Using the green compact of the lithium ion conductor according to Example 4, XRD measurement was performed in the same manner as in Example 1, and the lithium ion conductive oxide powder according to Example 4 was a lithium ion conductive oxide having a NASICON type crystal structure. It was found to be a powder (composition formula: Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ ).

<Example 5> (1) Preparation of raw material aqueous solution

(Ⅰ) Germanium aqueous solution

192.5 g of germanium dioxide was added to 4000 g of pure water, it was heated to 40°C while stirring, and 97.5 g of ammonia water having a concentration of 28% by mass as an alkali was further added to dissolve the germanium dioxide to prepare an aqueous germanium solution. The pH value in the prepared aqueous solution was 10.7 and was alkaline.

(Ⅱ) Aqueous solution containing lithium, aluminum and phosphorus

To 150 g of pure water, lithium nitrate 21.7 g, aluminum nitrate 9 hydrate 39.4 g, and ammonium dihydrogen phosphate 72.5 g were added to prepare an aqueous solution containing lithium, aluminum and phosphorus. The pH value in the prepared lithium, aluminum, and phosphorus containing aqueous solution was 1.4, and it was acidic.

(III) Aqueous solution containing titanium

After adding 3.0 g of aqueous ammonia with a density|concentration of 28 mass % to 35.8 g of 35 mass % of hydrogen peroxide solutions with a density|concentration, 1.51 g of metatitanic acid was added, and it stirred until it melt|dissolved completely. The lithium, aluminum, and phosphorus containing aqueous solution mentioned above was added to this solution. The pH value at this point was 4.0.

(2) mixing (slurrying)

684 g of the alkaline aqueous germanium solution was aliquoted and heated to 40° C. while stirring, and the entire amount of the acidic lithium, aluminum, phosphorus, and titanium-containing aqueous solution was added thereto. got it The pH value of the obtained white slurry was 6.7.

(3) amorphous lithium ion conducting oxide powder

Using the obtained white slurry, it operated similarly to Example 1, and the amorphous lithium ion conducting oxide powder which concerns on Example 5 was obtained. The composition formula of the obtained amorphous lithium ion conductive oxide powder was Li _1.5 Al _0.5 (Ge _1.4 Ti _0.1 ) P _3.0 O ₁₂ .

Using the amorphous lithium ion conductor powder according to Example 5, in the same manner as in Example 1, XRD measurement was performed. As a result, halos were observed in the region of 2θ: 15° to 40°, and the half width of the halo was 2θ: 2° It was more than that.

(Ⅰ) Calculation of the amount of oxygen

The amount of oxygen corresponding to the titanium contained in the amorphous lithium ion conductive oxide powder was calculated as follows.

Since the oxide of tetravalent titanium is TiO ₂ , the amount of oxygen according to the titanium oxide is expressed by the following formula.

Oxygen amount according to titanium oxide = (Ti concentration × (food of TiO ₂ / number of Ti atoms in TiO ₂ ) ÷ food of Ti) — Ti concentration… (ceremony)

On the other hand, since the analysis result of ICP of titanium concentration is 0.8 mass %,

Oxygen amount according to titanium oxide = (0.8 × (79.88/1) ÷ 47.88) - 0.8 = 0.53 mass%

becomes

The amorphous lithium ion conductor powder according to Example 5 was calcined at 700° C. for 120 minutes to obtain a crystallized lithium ion conductor, and also a green compact of the lithium ion conductor was obtained. The green compact of the lithium ion conductor was subjected to XRD measurement under the conditions described in “(V) XRD measurement of amorphous lithium ion conductive oxide powder” above, and compared with JCPDS card No. 01-080-1922, NASICON It coincided with the crystal peak of LiGeP ₃ O ₁₂ , which is a lithium ion conductor with a crystalline structure. Accordingly, it was found that the green fired body of the lithium ion conductive oxide powder according to Example 5 was a lithium ion conductor having a NASICON type crystal structure.

<Example 6> (1) Preparation of raw material aqueous solution

(Ⅰ) Germanium aqueous solution

192.5 g of germanium dioxide was added to 4000 g of pure water, it was heated to 40°C while stirring, and 97.5 g of ammonia water having a concentration of 28% by mass as an alkali was further added to dissolve the germanium dioxide to prepare an aqueous germanium solution. The pH value in the prepared aqueous solution was 10.7 and was alkaline.

(Ⅱ) Aqueous solution containing lithium, aluminum and phosphorus

To 150 g of pure water, 21.7 g of lithium nitrate, 39.4 g of aluminum nitrate 9hydrate, 72.5 g of ammonium dihydrogen phosphate, and an aqueous solution containing lithium, aluminum, and phosphorus were prepared. The pH value in the prepared lithium, aluminum, and phosphorus containing aqueous solution was 0.9, and was acidic.

(2) mixing (slurrying)

684 g of the alkaline germanium aqueous solution was aliquoted and heated to 40° C. while stirring, and 4.1 g of zirconium oxynitrate was added and completely dissolved. When the whole quantity of the said acidic lithium, aluminum, and phosphorus containing aqueous solution was added there, the aqueous solution became cloudy immediately after the said addition, and the white slurry was obtained. The pH value of the obtained white slurry was 3.9.

(3) amorphous lithium ion conducting oxide powder

Using the obtained white slurry, it operated similarly to Example 1, and the amorphous lithium ion conducting oxide powder which concerns on Example 5 was obtained. The composition formula of the obtained amorphous lithium ion conductive oxide powder was Li _1.5 Al _0.5 (Ge _1.4 Zr _0.1 )P _3.0 O ₁₂ .

Using the amorphous lithium ion conductor powder according to Example 5, in the same manner as in Example 1, XRD measurement was performed. As a result, halos were observed in the region of 2θ: 15° to 40°, and the half width of the halo was 2θ: 2° It was more than that.

(Ⅰ) Calculation of the amount of oxygen

The amount of oxygen corresponding to the zirconium contained in the amorphous lithium ion conductive oxide powder was calculated as follows.

Since the oxide of tetravalent zirconium is ZrO ₂ , the amount of oxygen corresponding to the titanium oxide is expressed by the following formula.

Oxygen amount according to zirconium oxide = (Zr concentration × (food of ZrO ₂ / number of Zr atoms in ZrO ₂ ) ÷ food of Zr) ― Zr concentration … (ceremony)

On the other hand, since the analysis result of ICP of zirconium concentration is 1.5 mass %,

Oxygen amount according to zirconium oxide = (1.5 × (123.22/1) ÷ 91.22) - 1.5 = 0.53 mass%

becomes

The amorphous lithium ion conductor powder according to Example 6 was calcined at 700° C. for 120 minutes to obtain a crystallized lithium ion conductor, and also a green compact of the lithium ion conductor was obtained. The green compact of the lithium ion conductor was subjected to XRD measurement under the conditions described in “(V) XRD measurement of amorphous lithium ion conductive oxide powder” above, and compared with JCPDS card No. 01-080-1922, NASICON It coincided with the crystal peak of LiGeP ₃ O ₁₂ , which is a lithium ion conductor with a crystalline structure. Accordingly, it was found that the green fired body of the lithium ion conductive oxide powder according to Example 6 was a lithium ion conductor having a NASICON type crystal structure.

<Example 7> (1) Preparation of raw material aqueous solution

(Ⅰ) Germanium aqueous solution

192.5 g of germanium dioxide was added to 4000 g of pure water, it was heated to 40°C while stirring, and 97.5 g of ammonia water having a concentration of 28% by mass as an alkali was further added to dissolve the germanium dioxide to prepare an aqueous germanium solution. The pH value in the prepared aqueous solution was 10.7 and was alkaline.

(Ⅱ) Aqueous solution containing lithium, aluminum and phosphorus

To 150 g of pure water, 23.9 g of lithium nitrate, 39.4 g of aluminum nitrate 9hydrate, and 68.9 g of ammonium dihydrogen phosphate were added to prepare an aqueous solution containing lithium, aluminum and phosphorus. The pH value in the prepared lithium, aluminum, and phosphorus containing aqueous solution was 1.6, and it was acidic.

(2) mixing (slurrying)

720 g of the alkaline germanium aqueous solution was fractionated, and 10.2 g of a Li ₂ O ₁₁ Si ₅ solution (manufactured by Sigma-Aldrich Co. LLC) was added thereto. The solution was heated to 40° C. while stirring, and the entire amount of the acidic lithium, aluminum, phosphorus, and titanium-containing aqueous solution was added thereto, and the aqueous solution became cloudy immediately after the addition to obtain a white slurry.

(3) amorphous lithium ion conducting oxide powder

Using the obtained white slurry, it operated similarly to Example 1, and the amorphous lithium ion conducting oxide powder which concerns on Example 7 was obtained. The composition formula of the obtained amorphous lithium ion conductive oxide powder was Li _1.5 Al _0.5 Ge _1.5 (P _2.96 Si _0.04 )O ₁₂ .

Using the amorphous lithium ion conductor powder according to Example 7, in the same manner as in Example 1, and XRD measurement was performed, halos were observed in the region of 2θ: 15° to 40°, and the half width of the halo was 2θ: 2° It was more than that.

(Ⅰ) Calculation of the amount of oxygen

The amount of oxygen corresponding to the silicon contained in the amorphous lithium ion conductive oxide powder was calculated as follows.

Since the oxide of tetravalent silicon is SiO ₂ , the amount of oxygen corresponding to the silicon oxide is expressed by the following formula.

Oxygen amount according to silicon oxide = (Si concentration × (food of SiO ₂ / number of Si atoms of SiO ₂ ) ÷ food of Si) — Si concentration… (ceremony)

On the other hand, since the analysis result of ICP of silicon concentration is 0.2 mass %,

Oxygen amount according to silicon oxide = (0.2 × (60.08/1) ÷ 28.09) - 0.2 = 0.23 mass%

becomes

The amorphous lithium ion conductor powder according to Example 7 was calcined at 700° C. for 120 minutes to obtain a crystallized lithium ion conductor, and also a green compact of the lithium ion conductor was obtained. The green compact of the lithium ion conductor was subjected to XRD measurement under the conditions described in “(V) XRD measurement of amorphous lithium ion conductive oxide powder” above, and compared with JCPDS card No. 01-080-1922, NASICON It coincided with the crystal peak of LiGeP ₃ O ₁₂ , which is a lithium ion conductor with a crystalline structure. Accordingly, it was found that the green fired body of the lithium ion conductive oxide powder according to Example 7 was a lithium ion conductor having a NASICON type crystal structure.

<Example 8> (1) Preparation of raw material aqueous solution

(Ⅰ) Germanium aqueous solution

192.5 g of germanium dioxide was added to 4000 g of pure water, it was heated to 40°C while stirring, and 97.5 g of ammonia water having a concentration of 28% by mass as an alkali was further added to dissolve the germanium oxide to prepare an aqueous germanium solution. The pH value in the prepared aqueous solution was 10.7 and was alkaline.

(Ⅱ) Aqueous solution containing lithium, aluminum and phosphorus

Lithium acetate 22.9g, aluminum nitrate 9 hydrate 39.4g, and ammonium dihydrogenphosphate 72.5g were added to 150 g of pure water, lithium, aluminum, and phosphorus containing aqueous solution was prepared. The pH value in the prepared lithium, aluminum, and phosphorus containing aqueous solution was 1.8, and it was acidic.

(2) mixing (slurrying)

720 g of the alkaline germanium aqueous solution was aliquoted and heated to 40° C. while stirring, and the entire amount of the acidic lithium, aluminum, phosphorus, and titanium-containing aqueous solution was added thereto, and the aqueous solution became cloudy immediately after the addition, forming a white slurry got it The pH value of the obtained white slurry was 4.5.

(3) amorphous lithium ion conducting oxide powder

Using the obtained white slurry, it operated similarly to Example 1, and the amorphous lithium ion conducting oxide powder which concerns on Example 8 was obtained. The composition formula of the obtained amorphous lithium ion conductive oxide powder was Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ .

Using the amorphous lithium ion conductor powder according to Example 8, XRD measurement was performed in the same manner as in Example 1, and halos were observed in the region of 2θ: 15° to 40°, and the half width of the halo was 2θ: 2° It was more than that.

Using the amorphous lithium ion conductor powder according to Example 8, in the same manner as in Example 1, a lithium ion conductive oxide powder according to Example 8 was obtained, and a green compact of a lithium ion conductor was obtained.

Using the green compact of the lithium ion conductor according to Example 8, XRD measurement was performed in the same manner as in Example 1, and the lithium ion conductive oxide powder according to Example 8 was a lithium ion conductive oxide having a NASICON type crystal structure. It was found to be a powder (composition formula: Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ ).

(Comparative Example 1)

An amorphous lithium ion conductive oxide powder according to Comparative Example 1 was prepared by a flowchart showing a manufacturing process of the lithium ion conductive oxide powder according to Comparative Example 1 shown in FIG. 5 . Then, analysis and characteristic evaluation of the lithium ion conductive oxide powder according to Comparative Example 1 were performed.

(1) Germanium, aluminum solution preparation

To 97.68 g of butanol, 410 g of Ge(OEt) and 33.25 g of Al(OBt) were added and dissolved to prepare a Ge and Al solution.

(2) Preparation of lithium and phosphorus solutions

To 379.64 g of pure water, 2.61 g of LiCOOCH ₃ and 9.098 g of (NH ₄ ) ₂ HPO ₄ were added and dissolved to prepare a lithium and phosphorus solution.

(3) mixing (solization)

The germanium and aluminum solution and the lithium and phosphorus solution were mixed to obtain a mixed solution.

(4) Drying → vacuum drying

The mixed solution was dried under an atmosphere of 100°C, and then vacuum dried at 110°C to obtain a powder.

(5) firing

The powder obtained by the vacuum drying was calcined at 400° C. under a nitrogen atmosphere to obtain an amorphous lithium ion conductive oxide powder according to Comparative Example 1.

Fig. 2 shows an SEM photograph of 30,000 times the obtained amorphous lithium ion conductive oxide powder.

(6) crushing

40 g of the amorphous lithium ion conductive oxide powder according to Comparative Example 1 was loaded into a bead mill together with 160 g of φ1 mm Zr beads and 94.32 g of IPA, and then pulverized for 120 minutes to obtain a lithium ion conductive oxide powder whose particle size was adjusted.

(7) drying

The lithium ion conductive oxide powder whose particle size was adjusted was put in a dryer, dried at 100° C. for 3 hours, and IPA was removed to obtain a lithium ion conductive oxide powder according to Comparative Example 1.

The volume-based cumulative 50% particle diameter (D ₅₀ ) of the lithium ion conductive oxide powder according to Comparative Example 1 was 1.5 µm as measured by Helos (dispersion pressure 5 bar).

(8) Composition analysis of amorphous lithium ion conducting oxide powder

The amorphous lithium ion conductive oxide powder according to Comparative Example 1 was subjected to elemental analysis in the same manner as in Example 1, Li 2.40 (mass %), Al 2.94 (mass %), Ge 25.2 (mass %), and P 21.7 (mass %) ) was obtained. Table 2 shows the composition of each constituent element.

(9) Analysis of carbon content and oxygen content of amorphous lithium ion conductive oxide powder

When the amount of carbon and the amount of oxygen in the amorphous lithium ion conductive oxide powder according to Comparative Example 1 were measured in the same manner as in Example 1, the amount of carbon was 0.38% by mass and the amount of oxygen was 44.5% by mass. The obtained amorphous lithium ion conductive oxide powder was Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ . In addition, the amount of impurities was calculated to be 2.9 mass % from the respective amounts of the above-described metallic elements, phosphorus, carbon, and oxygen. These values are shown in Table 2.

(10) Measurement of BET specific surface area of amorphous lithium ion conducting oxide powder

The BET specific surface area of the amorphous lithium ion conductive oxide powder according to Comparative Example 1 was 12.3 m 2 /g when measured in the same manner as in Example 1. These values are shown in Table 3.

(11) XRD measurement of amorphous lithium ion conducting oxide powder

The amorphous lithium ion conductive oxide powder according to Comparative Example 1 was subjected to XRD measurement under the same measurement conditions as in Example 1. In the obtained XRD spectrum, it was confirmed that the lithium ion conductor according to Comparative Example 1 was amorphous because halo was confirmed as in Example 1. Table 3 shows this point.

(12) Evaluation of ion conductivity of lithium ion conductive oxide powder having NASICON type crystal structure

For the amorphous lithium ion conductive oxide powder according to Comparative Example 1, the same operation as in Example 1 was performed to prepare a green compact of the lithium ion conductive oxide powder having a NASICON type crystal structure according to Comparative Example 1.

For the green fired body of the lithium ion conductive oxide powder having a NASICON type crystal structure according to Comparative Example 1, the ionic conductivity was calculated in the same manner as in Example 1, and the result was 4.6 × 10 ^-6 S/cm. These values are shown in Table 3.

In addition, as a result of XRD measurement of the green compact having a NASICON-type crystal structure according to Comparative Example 1 as in Example 1, it was found that it was a lithium ion conductor having a NASICON-type crystal structure.

(Comparative Example 2)

By the flowchart showing the manufacturing process of the amorphous lithium ion conductive oxide powder according to Comparative Example 2 shown in FIG. 6, the lithium ion conductive oxide powder (Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ ) according to Comparative Example 2 was prepared did. And analysis and characteristic evaluation of the lithium ion conductive oxide powder according to Comparative Example 2 were performed.

(1) Weighing and mixing of raw materials

As raw material powder, Li ₂ CO ₃ 2.85 g, Al ₂ O ₃ 1.31 g, GeO ₂ 8.08 g, NH ₄ H ₂ PO ₄ 17.76 g were weighed. And each weighed raw material powder was put into a self-made mortar, and it mixed and obtained the mixed powder.

(2) firing

The obtained mixed powder was placed in an alumina crucible, and calcined at a temperature of 400° C. in an air atmosphere for 5 hours to obtain a calcined component.

(3) dissolution

The obtained calcined component was put in a platinum crucible and heated at a temperature of 1200°C for 1 hour to obtain a melted product.

(4) quench

The lysate was quenched and vitrified to obtain a glassy powder.

An SEM photograph of 10,000 times the obtained vitreous is shown in FIG. 2 .

(5) crushing

The obtained glass powder was roughly crushed in a mortar to obtain powder having a particle size of 200 µm or less. Thereafter, in the same manner as in Example 1, wet grinding was performed using IPA as a solvent to obtain an amorphous lithium ion conductive oxide powder whose particle size was adjusted.

(6) drying

The lithium ion conductive oxide powder whose particle size was adjusted was put in a dryer, dried at 100° C. for 3 hours, and IPA was removed to obtain an amorphous lithium ion conductor powder according to Comparative Example 2.

(7) Composition analysis of amorphous lithium ion conducting oxide powder

The amorphous lithium ion conductive oxide powder according to Comparative Example 2 was subjected to elemental analysis as in Example 1, Li 2.39 (mass %), Al 2.98 (mass %), Ge 24.5 (mass %), and P 21.8 (mass %) ) was obtained. Table 2 shows the values of the composition of each constituent element.

(8) Analysis of carbon content and oxygen content of amorphous lithium ion conductive oxide powder

When the amount of carbon and the amount of oxygen in the amorphous lithium ion conductive oxide powder according to Comparative Example 2 were measured in the same manner as in Example 1, the amount of carbon was 0.041 mass% and the amount of oxygen was 44.4 mass%. The obtained amorphous lithium ion conductive oxide powder was Li _1.5 Al _0.5 Ge _1.5 P _3.0 O ₁₂ . In addition, the amount of impurities was calculated as 3.9 mass % from each amount of the above-mentioned metallic element, phosphorus, carbon, and oxygen. These values are shown in Table 2.

(9) BET specific surface area measurement of amorphous lithium ion conducting oxide powder

The BET specific surface area of the amorphous lithium ion conductive oxide powder according to Comparative Example 2 was measured in the same manner as in Example 1, and was found to be 3.3 m 2 /g. These values are shown in Table 3.

(10) XRD measurement of amorphous lithium ion conducting oxide powder

The amorphous lithium ion conductive oxide powder according to Comparative Example 2 was subjected to XRD measurement under the same measurement conditions as in Example 1. In the obtained XRD spectrum, it was confirmed that the amorphous lithium ion conductor according to Comparative Example 2 was amorphous because halo was confirmed as in Example 1. Table 3 shows this point.

(11) Evaluation of ionic conductivity of lithium ion conductive oxide powder having a NASICON type crystal structure

For the amorphous lithium ion conductive oxide powder according to Comparative Example 2, the same operation as in Example 1 was performed to prepare a green compact of lithium ion conductive oxide powder having a NASICON type crystal structure according to Comparative Example 2.

With respect to the green compact of the lithium ion conductive oxide powder having a NASICON type crystal structure according to Comparative Example 2, the ionic conductivity was calculated as in Example 1 and found to be 2.2 × 10 ^-5 S/cm. Table 3 shows this point.

Further, as a result of XRD measurement of the green compact having a NASICON-type crystal structure according to Comparative Example 2 as in Example 1, it was found that it was a lithium ion conductor having a NASICON-type crystal structure.

[Table 2]

[Table 3]

[Table 4]

Claims (15)

0.5 mass % or more and 6.5 mass % or less of lithium;
More than 0 mass % and 25.0 mass % or less of aluminum,
More than 0 mass % of germanium 65.0 mass % or less,
It contains 10 mass % or more and 30 mass % or less of phosphorus,
An amorphous lithium ion conductive oxide powder having a specific surface area of 15 m 2 /g or more and 100 m 2 /g or less measured by the BET one-point method. The method of claim 1,
1 mass % or more and 4 mass % or less of lithium;
More than 0 mass % and 6 mass % or less of aluminum,
Amorphous lithium ion conductive oxide powder containing more than 15 mass % and 35 mass % or less of germanium. 3. The method of claim 1 or 2,
The amorphous lithium ion conductive oxide powder which further contains 0.01 mass % or more and 0.35 mass % or less of carbon. 4. The method according to any one of claims 1 to 3,
An amorphous lithium ion conductive oxide powder having a specific surface area of 20 m 2 /g or more and 100 m 2 /g or less measured by the BET one-point method. 5. The method according to any one of claims 1 to 4,
An amorphous lithium ion conducting oxide powder further comprising at least one element selected from titanium, zirconium and hafnium. 6. The method according to any one of claims 1 to 5,
The amorphous lithium ion conductive oxide powder which further contains 10 mass % or less of silicon. 7. The method according to any one of claims 1 to 6,
The amorphous lithium ion conductive oxide powder is represented by the formula of the general formula Li _1+x+w (Al _1-y M1 _y ) _x (Ge _1-z M2 _z ) _2-x P _3-w Si _w O ₁₂ , M1 is gallium , lanthanum, indium, and at least one selected from yttrium, M2 is at least one selected from titanium, zirconium, and hafnium, the range of x is 0 < x ≤ 1.0, the range of y is 0 ≤ y ≤ 1.0, z Amorphous lithium ion conducting oxide powder with a range of 0 ≤ z ≤ 1.0, and a range of w of 0 ≤ w ≤ 1.0. 7. The method according to any one of claims 1 to 6,
An amorphous lithium ion conducting oxide powder further comprising at least one element selected from gallium, lanthanum, indium and yttrium. A slurry forming step of mixing an aqueous solution of a lithium compound, an aqueous solution of an aluminum compound, an aqueous solution of a germanium compound, and an aqueous solution of an ammonium phosphate salt to obtain a suspension of a coprecipitate;
spray-drying the slurry to obtain a dried slurry;
The manufacturing method of the amorphous lithium ion conductive oxide powder which has the process of calcining the said slurry dried product at 300 degreeC or more and 500 degrees C or less. 10. The method of claim 9,
In the slurry forming step, an aqueous solution of a compound further containing at least one element selected from gallium, lanthanum, indium and yttrium is mixed to obtain a suspension of a coprecipitate, a method for producing an amorphous lithium ion conducting oxide powder. 11. The method of claim 9 or 10,
In the slurry forming step, an aqueous solution of a compound further containing at least one element selected from titanium, zirconium and hafnium is mixed to obtain a suspension of a coprecipitate, a method for producing an amorphous lithium ion conducting oxide powder. 12. The method according to any one of claims 9 to 11,
In the slurry forming step, an aqueous solution of a silicon compound is further mixed to obtain a suspension of a co-precipitate, a method for producing an amorphous lithium ion conductive oxide powder. 13. The method according to any one of claims 9 to 12,
The method for producing an amorphous lithium ion conductive oxide powder, wherein the suspension is formed in the slurry forming step by mixing an aqueous solution of the germanium compound adjusted to pH 8 or higher. A method for producing a lithium ion conductive oxide powder having a NASICON type crystal structure, comprising a step of calcining the amorphous lithium ion conductive oxide powder according to any one of claims 1 to 8 at a temperature higher than 500°C. A slurry forming step of mixing an aqueous solution of a lithium compound, an aqueous solution of an aluminum compound, an aqueous solution of a germanium compound, and an aqueous solution of an ammonium phosphate salt to obtain a suspension of a coprecipitate;
spray-drying the slurry to obtain a dried slurry;
A method for producing a lithium ion conductive oxide powder having a NASICON-type crystal structure, comprising a step of calcining the dried slurry at a temperature higher than 500°C.

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