JP2012031025A - Garnet-type lithium ion-conducting oxide and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a garnet-type lithium ion-conducting oxide which has high conductivity and has a small rate of change of conductivity against temperature.SOLUTION: The garnet-type lithium ion-conducting oxide includes aluminum in a skeleton represented by LiLn(MM)O(wherein Ln is one or more sorts of elements selected from the group consisting of La, Pr, Nd, etc., Mis one or more sorts of elements selected from the group consisting of Si, Sc, Ti, V, Ga, Ge, Y, Zr, Nb, In, Sb, Te, Hf, Ta, W, and Bi, Mis an element different from Mand one or more sorts of elements selected from the group consisting of Sc, Ti, V, Y, Nb, Hf, Ta, Si, Ga and Ge, x is a number which satisfies 3≤x≤8, y and z are numbers which satisfy y>0, z≥0, 1.9≤y+z≤2.1, and t is a number which satisfies 11≤t≤13).

Description

  The present invention relates to a garnet-type lithium ion conductive oxide and a method for producing the same.

  Compared to a lithium secondary battery using a non-aqueous electrolyte, the all solid-state lithium ion secondary battery uses a solid electrolyte, so there is no fear of ignition. However, high-capacity all solid-state lithium ion secondary batteries have not yet been put into practical use even in the world. One of the causes is a problem of the solid electrolyte itself. There are three main characteristics required for a solid electrolyte: high lithium ion conductivity (conductivity), excellent chemical stability, and a wide potential window. A garnet oxide is one of the promising candidates for a solid electrolyte because of its excellent chemical stability and wide potential window among these characteristics (see, for example, Non-Patent Documents 1 and 2).

J. Am. Ceram. Soc., 2003, 86, 3, 437-440 Angew. Chem. Int. Ed., 2007, 46, 7778-7781

  Such garnet-type oxides are desired to have further improved characteristics. In particular, it is desired to increase the conductivity and reduce the rate of change in conductivity with respect to temperature.

  The main object of the present invention is to provide a garnet-type lithium ion conductive oxide having a high conductivity and a small rate of change in conductivity with respect to temperature.

  In order to achieve the above-described object, the present inventors have conducted intensive research. As a result, by adding an appropriate amount of Al to a garnet-type lithium ion conductive oxide, the conductivity is improved and the activity of the conductivity is improved. It has been found that the rate of change in electrical conductivity with respect to temperature becomes smaller due to the decrease in chemical energy, and the present invention has been completed.

That is, the garnet-type lithium ion conductive oxide of the present invention is
Li _x Ln ₃ (M ¹ _y M ² _z ) O _t (1)
(In the formula (1), Ln is one or more elements selected from the group consisting of La, Pr, Nd, Sm, Lu, Y, K, Mg, Ba, Ca, Sr,
M ¹ is one or more elements selected from the group consisting of Si, Sc, Ti, V, Ga, Ge, Y, Zr, Nb, In, Sb, Te, Hf, Ta, W, Bi,
M ² is an element different from M ^1, and one or more elements selected from the group consisting of Sc, Ti, V, Y, Nb, Hf, Ta, Si, Ga, and Ge,
x is a number satisfying 3 ≦ x ≦ 8,
y and z are numbers satisfying y> 0, z ≧ 0, 1.9 ≦ y + z ≦ 2.1,
t is a number satisfying 11 ≦ t ≦ 13)
Al is contained in the skeleton represented by the formula, and Al is contained in the crystal lattice of the Li _x Ln ₃ (M ¹ _y M ² _z ) O _t and the Li _x Ln ₃ (M ¹ _y M ² _z ) O. It exists in at least one of the grain boundaries between the grains of _t .

The method for producing the garnet-type lithium ion conductive oxide of the present invention is as follows:
A method for producing the above-described garnet-type lithium ion conductive oxide,
(A) Each starting material containing each element of formula (1) is weighed so as to have a stoichiometric ratio of formula (1), and the mixed powder is calcined, and then the calcined powder is A step of adding a lithium compound to make up for the loss of Li in the main sintering, and pre-sintering the powder to which the lithium compound has been added to obtain a pre-sintering powder;
(B) After the pre-sintering powder is formed, main sintering is performed in an alumina firing container, or after the pre-sintering powder is added with a compound containing an Al element, the main sintering is performed. A step of obtaining the above-described garnet-type lithium ion conductive oxide by
Is included.

According to the garnet-type lithium ion conductive oxide of the present invention, the conductivity is improved as compared with the conventional garnet-type lithium ion conductive oxide, and the activation energy of the conductivity is reduced, so that the conductivity with respect to the temperature is reduced. The effect of reducing the rate of change of is obtained. Although the mechanism for obtaining such an effect is not clear, for example, the following (1) and (2) are conceivable. (1) When at least a part of Al is taken into the crystal lattice of garnet and is replaced with a part of the Li site, the following mechanism is considered. That is, it is known that the Li site of the lithium ion conductive garnet-type oxide has 4 or 6 coordination, the Ln site has 8 coordination, and the M ¹ and M ² sites have 6 coordination. Yes. Al is generally tetracoordinate or hexacoordinate, and thus may be substituted with a Li site, an M ¹ site, or an M ² site. However, since the Li site originally has many empty sites, it is considered that Al is easily replaced with the Li site. Comparing the ionic radii of Al and Li, Al ³⁺ (4-coordinate: 0.39Å, 6-coordinate: 0.535Å), Li ⁺ (4-coordinate: 0.59Å, 6-coordinate: 0.76Å) It is. For this reason, when Al substitutes for the Li site, the Al—O distance is short, so the Li—O distance is slightly increased, and Li ions are likely to be conducted. However, if the amount of Al becomes too large, it is considered that Al inhibits Li conduction. From the above, it is considered that there is an appropriate amount of Al to be added. (2) When at least a part of Al is present in the grain boundary of garnet, the following mechanism can be considered. That is, it is considered that Al in the grain boundary acts as a sintering aid for the solid electrolyte, increases the sintered density of the electrolyte, lowers the grain boundary resistance, and as a result, improves the conductivity. The garnet-type lithium ion conductive oxide of the present invention can be applied to an all-solid-state lithium ion secondary battery, and is particularly expected to be applied to a secondary battery mounted on an automobile that requires high output. Is done.

It is a graph which shows a XRD pattern. It is a graph which shows the relationship between the molar ratio of Al with respect to La3 mol, and 25 degreeC electrical conductivity. It is a graph which shows the relationship between the molar ratio of Al with respect to La3 mol, and the activation energy of electrical conductivity. It is a graph which shows the relationship between the molar ratio of Al with respect to La3 mol, and a lattice constant.

The garnet-type lithium ion conductive oxide of the present invention contains Al in the skeleton represented by the formula (1), that is, Li _x Ln ₃ (M ¹ _y M ² _z ) O _t , and Al is the Li being present in at least one of ^{_{x Ln 3 (M 1 y M}} 2 z) within the crystal lattice of O _t and the ^{_{Li x Ln 3 (M 1 y}} M 2 z) grain boundary between O _t of the particles. Here, Ln is one or more elements selected from the group consisting of La, Pr, Nd, Sm, Lu, Y, K, Mg, Ba, Ca, and Sr, and among these, La is preferable. M ¹ is one or more elements selected from the group consisting of Si, Sc, Ti, V, Ga, Ge, Y, Zr, Nb, In, Sb, Te, Hf, Ta, W, and Bi. Of these, Zr is preferred. M ² is an element different from M ¹ and is one or more elements selected from the group consisting of Sc, Ti, V, Y, Nb, Hf, Ta, Si, Ga, and Ge. Of these, Nb is preferred. x is a number that satisfies 3 ≦ x ≦ 8, but preferably satisfies 5 ≦ x ≦ 7. Further, x may be 5 + y. y and z are numbers satisfying y> 0, z ≧ 0, 1.9 ≦ y + z ≦ 2.1. y preferably satisfies 1.4 ≦ y <2, and more preferably satisfies 1.625 ≦ y ≦ 1.875. z may be 2-y. t is a number satisfying 11 ≦ t ≦ 13 (for example, 12). Al is preferably contained in an amount of 0.05 mol or more and 0.30 mol or less, and more preferably 0.07 mol or more and 0.25 mol or less, relative to 3 mol of Ln.

The garnet-type lithium ion conductive oxide of the present invention can be used for an all solid-state lithium secondary battery. Such a secondary battery has a garnet-type lithium ion conductivity according to the present invention between a positive electrode having a positive electrode active material capable of occluding and releasing lithium ions and a negative electrode having a negative electrode active material capable of occluding and releasing lithium ions. An oxide may be interposed. As the positive electrode active material, a sulfide containing a transition metal element, an oxide containing lithium and a transition metal element, or the like can be used. Specifically, transition metal sulfides such as TiS ₂ , TiS ₃ , MoS ₃ , and FeS ₂ , Li _(1-a) MnO ₂ (0 ≦ a <1, etc., the same shall apply hereinafter), Li _(1-a) Mn Lithium manganese composite oxide such as ₂ O ₄ , lithium cobalt composite oxide such as Li _(1-a) CoO ₂ , lithium nickel composite oxide such as Li _(1-a) NiO ₂ , lithium such as LiV ₂ O ₃ Vanadium composite oxides, transition metal oxides such as V ₂ O _{5, and the} like can be used. Of these, lithium transition metal composite oxides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , and LiV ₂ O ₃ are preferable. In addition, examples of the negative electrode active material include inorganic compounds such as lithium, lithium alloys, and tin compounds, carbonaceous materials that can occlude and release lithium ions, and conductive polymers. Of these, carbonaceous materials are safe. It is preferable from the viewpoint. The carbonaceous material is not particularly limited, and examples thereof include cokes, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, and carbon fibers. Of these, graphites such as artificial graphite and natural graphite have an operating potential close to that of metallic lithium, can be charged and discharged at a high operating voltage, and suppresses self-discharge when a lithium salt is used as an electrolyte salt. In addition, the irreversible capacity during charging can be reduced, which is preferable.

  An example of the manufacturing method of the garnet-type lithium ion conductive oxide of this invention is demonstrated. This oxide manufacturing method includes (a) a step of producing a pre-sintering powder, and (b) forming a pre-sintering powder and then performing a main sintering in an alumina firing container. And a step of performing main sintering after forming a powder obtained by adding a compound containing Al element to the powder before sintering. Among these, the step (a) includes 1) a first mixing step, 2) a first calcination step, 3) a second mixing step, and 4) a second calcination step. Hereinafter, steps 1) to 4) and step (b) of step (a) will be described in order.

(A) Preparation of powder before main sintering 1) First mixing step In the first mixing step, the formula (1), that is, Li _x Ln ₃ (M ¹ _y M ² _z ) O _t (Ln, M ¹ , M ² , (x, y, z, and t are as described above) The starting materials containing each element are weighed and mixed so as to have a stoichiometric ratio of the formula (1). As starting materials, carbonates, sulfates, nitrates, oxalates, chlorides, hydroxides, oxides and the like of each element can be used. Of these, carbonates that thermally decompose to generate carbon dioxide and hydroxides that thermally decompose to generate water vapor are preferable because they are relatively easy to process. For example, it is preferable to use Li carbonate, Ln hydroxide, M ¹ oxide, and M ² oxide. The mixing method may be dry mixing and pulverization without adding a solvent, or may be mixed and pulverized wet in a solvent. From the standpoint of this, it is preferable. As this mixing method, for example, a planetary mill, an attritor, a ball mill, or the like can be used. As the solvent, those in which Li is difficult to dissolve are preferable, and for example, an organic solvent such as ethanol is more preferable. The mixing time depends on the amount of mixing, but can be 2h to 8h, for example.

2) First calcination step In the first calcination step, the mixed powder obtained in the first mixing step is calcined. The calcining temperature at this time is preferably not less than the temperature at which the state change (for example, gas generation or phase change) of the starting material occurs and less than the temperature during the main sintering. For example, when Li ₂ CO ₃ is used as one of the starting materials, it is preferable that the temperature be higher than the temperature at which the carbonate is decomposed and lower than the temperature at the time of main sintering. If it carries out like this, the fall of the density by the gas generation | occurrence | production by thermal decomposition can be suppressed in subsequent main sintering. Specifically, the calcination temperature is preferably 900 ° C. to 1150 ° C.

3) Second mixing step In the second mixing step, a lithium compound (for example, lithium carbonate) is added to the calcined powder obtained in the first calcining step to compensate for the loss of Li in the main sintering, and mixed. To do. The addition amount at this time is determined empirically according to each condition of the firing process such as the first calcining process, the second calcining process, and the main sintering process. In the second mixing step, the amount of Li is 4 atomic% (at.%) Or more and 20 at. It is preferable to add Li corresponding to a range of% or less.

4) Second calcination step In the second calcination step, the mixed powder obtained in the second mixing step is calcined. This step may be performed under the same conditions as the first calcination step, but is preferably performed at a temperature higher than the temperature at which the state change of the lithium compound occurs and lower than the calcination temperature of the first calcination step. For example, when lithium carbonate is used as the lithium compound, it is preferable that the temperature be higher than the temperature at which the carbonate is decomposed and lower than the calcination temperature in the first calcination step. By doing so, the re-calcined material is suppressed from solidifying, and therefore it is preferable that the re-calcined material does not need to be pulverized before the main sintering step. Further, in the second calcination step, the amount of material that needs to be changed as compared with the first calcination step is small, and therefore the calcination time may be shortened. By performing this second calcining step, it is possible to suppress a decrease in density accompanying a change in state of the lithium compound added in the second mixing step in the subsequent main sintering step. Specifically, the calcination temperature is preferably 900 ° C. to 1150 ° C.

(B) Main sintering of powder before main sintering In this main sintering, the material obtained in the second calcining step (referred to as powder before main sintering) is molded and then main sintering is performed in an alumina firing container. Alternatively, the main sintering is performed after forming a powder obtained by adding a compound containing Al element (for example, alumina) to the powder before the main sintering. In the latter case, the firing container may be made of alumina or may be made of other materials. The temperature of the main sintering is set higher than the first calcination temperature and the second calcination temperature. Since the pre-sintered powder is calcined twice and rarely solidified or fixed, it can be formed into a molded body relatively easily by simple crushing. Molding into a compact can be performed by subjecting the pre-sintered powder to an arbitrary shape by cold isotropic molding (CIP), hot isotropic molding (HIP), mold molding, hot pressing, or the like.

  According to the manufacturing method described in detail above, after calcining the mixed powder of the starting material, the addition amount of the lithium compound empirically obtained is added and recalcined, and then the main sintering is performed. Can be accurately controlled. In addition, the manufacturing method of the garnet-type lithium ion conductive oxide of this invention is not limited to this, You may employ | adopt another manufacturing method.

[Preparation of powder before sintering]
In order to demonstrate the effect of the present invention, Li _6.75 La ₃ (Zr _1.75 Nb _0.25 ) O ₁₂ was taken up as an example of a garnet-type lithium ion conductive oxide. Li ₂ CO ₃ , La (OH) ₃ , ZrO ₂ , and Nb ₂ O ₅ were used as starting materials. First, starting materials were weighed so as to have a stoichiometric ratio, and mixed and pulverized for 2 hours in a planetary ball mill (300 rpm / zirconia balls) in ethanol (first mixing step). After the mixed powder of the starting material was separated from the balls and ethanol, calcination was performed in an alumina crucible in an air atmosphere at 950 ° C. for 10 hours (first calcination step). Thereafter, in order to make up for the loss of Li in the main sintering, the calcined powder was added to the Li amount in the composition of Li _6.75 La ₃ (Zr _1.75 Nb _0.25 ) O ₁₂ at 10 at. Li ₂ CO ₃ was excessively added so as to be a%. This mixed powder was treated in a planetary ball mill (300 rpm / zirconia ball) for 2 hours in ethanol for mixing (second mixing step). The obtained powder was again calcined again at 950 ° C. for 10 hours under atmospheric conditions (second calcining step) to obtain a pre-sintered powder.

[Example 1]
The pre-sintered powder was formed into a pellet and subjected to main sintering in an alumina firing container at 1180 ° C. for 36 hours in the atmosphere to prepare a pellet sample.

[Example 2]
0.9 wt% alumina was added to the pre-sintered powder and thoroughly dry mixed in an alumina mortar for 30 minutes. Thereafter, pellet molding was performed, and main sintering was performed in an alumina firing container at 1180 ° C. for 36 hours in the air to prepare a pellet sample.

[Example 3]
1.5 wt% alumina was added to the pre-sintered powder and thoroughly dry mixed in an alumina mortar for 30 minutes. Thereafter, pellet molding was performed, and main sintering was performed in an alumina firing container at 1180 ° C. for 36 hours in the air to prepare a pellet sample.

[Example 4]
3 wt% alumina was added to the pre-sintered powder and thoroughly dry mixed in an alumina mortar for 30 minutes. Thereafter, pellet molding was performed, and main sintering was performed in an alumina firing container at 1180 ° C. for 36 hours in the air to prepare a pellet sample.

[Comparative Example 1]
Al ₂ O ₃ was also mixed at the stage of the first mixing step in producing the pre-sintered powder. The mixing amount was 0.15 mol of Al with respect to 3 mol of La. Other than that, the powder before this sintering was produced in the same procedure as [Production of powder before this sintering]. The obtained pre-sintered powder was formed into a pellet and subjected to main sintering in an alumina firing container at 1180 ° C. for 36 hours in the air to prepare a pellet sample.

[Comparative Example 2]
The pre-sintered powder was formed into a pellet and subjected to main sintering in a zirconia firing container at 1180 ° C. for 36 hours in the air to prepare a pellet sample.

[Measurement of conductivity]
Using an AC impedance analyzer in a thermostatic chamber (frequency: 40 Hz to 110 MHz, amplitude voltage: 100 mV), the resistance value was obtained from the arc of the Nyquist plot, and the conductivity was calculated from this resistance value. An Au electrode was used as a blocking electrode when measuring with an AC impedance analyzer. The Au electrode was formed by baking a commercially available Au paste at 850 ° C. for 30 minutes. The obtained conductivity is summarized in Table 1.

The samples obtained in Examples 1 to ⁴ showed a high conductivity of 3 × 10 ⁻⁴ S / cm or more. In particular, the samples obtained in Examples 1 to 3 showed high conductivity of 6 × 10 ⁻⁴ S / cm or more. On the other hand, the sample obtained in Comparative Example 2 showed a low conductivity of 3 × 10 ⁻⁵ S / cm. Further, the conductivity of the sample obtained in Comparative Example 1 could not be estimated in the measurement frequency range of 40 Hz to 110 MHz.

[Identification of crystal structure]
The phase of each sample was determined from the XRD measurement results. The XRD measurement was performed using an XRD measuring instrument (D8ADVANCE, manufactured by Bruker, Inc.) using CuKα, 2θ: 10 to 120 °, 0.01 ° step / 1 sec. It measured on condition of this. The XRD patterns of the samples obtained in Examples 1 to 5 and Comparative Example 1 are shown in FIG. 1 (enlarged view of 10 ° to 50 °). From the XRD pattern of FIG. 1, the samples obtained in Examples 1 to 4 and Comparative Example 1 were considered to be a garnet single phase, and other peaks were not detected. On the other hand, a La ₂ Zr ₂ O ₇ peak was detected from the sample obtained in Comparative Example 2.

Although the sample obtained in Comparative Example 1 had a garnet single phase, its conductivity was so low that it could not be measured. The reason is considered as follows. Some pores were present in the pellet of Comparative Example 1. This is because Al ₂ O ₃ was mixed at the stage of mixing the starting materials, so LaAlO ₃ was present at the stage of the powder before the main sintering (confirmed by XRD measurement), and this changed to garnet during the main sintering. In this case, it is considered that pores were generated, and as a result, the conductivity of the solid electrolyte was lowered.

  Since the sample obtained in Comparative Example 2 uses zirconia in the crucible, it is considered that Al is not present in the sample. On the other hand, since Examples 1 to 4 use alumina for the crucible and add alumina during the main sintering depending on the sample, Al is present in the pellets. Table 2 shows the results of ICP emission analysis for the number of moles of Al relative to 3 moles of La in the solid electrolyte pellets of Examples 1 to 4.

As shown in Table 2, Al was detected in the sample from which the garnet single-phase XRD pattern was obtained. From the above, it is considered that by mixing Al, generation of impurities such as La ₂ Zr ₂ O ₇ was suppressed, and a sample having high conductivity was obtained. However, if Al is mixed in the calcination stage, voids are generated in the pellet during the main sintering, and an electrolyte having a high conductivity cannot be obtained. Therefore, it is desirable to mix Al during the main sintering. I understood that.

[Relation between Al content and various parameters]
Next, FIG. 2 shows the relationship between the number of moles of Al (referred to as pellet Al amount vs. La3) and the 25 ° C. conductivity relative to La3 mole in the solid electrolyte pellet. In addition, the amount of pellets Al. FIG. 3 shows the relationship between La3 and the activation energy of conductivity. The activation energy (Ea) is calculated from the conductivity data up to 25 ° C. to 100 ° C. from the Arrhenius equation: σ = Aexp (−Ea / kT) (σ: conductivity, A: frequency factor, k: Boltzmann constant, T : Absolute temperature) and calculating the slope of the Arrhenius plot. Furthermore, the pellet Al amount vs. FIG. 4 shows the relationship between La3 and the lattice constant of the crystal structure (determined from XRD measurement data).

  As shown in FIGS. 2 and 3, the sample containing Al in the solid electrolyte showed high conductivity and low activation energy. In particular, excellent characteristics were exhibited when Al was 0.05 to 0.30 mol (especially 0.07 to 0.25 mol) with respect to 3 mol of La. In addition, as shown in FIG. 4, as the amount of Al in the pellet increased, the lattice constant tended to decrease slightly, so that a part of Al in the pellet may exist in the garnet crystal structure. It is suggested.

[Other Examples]
In the preparation of the above-mentioned pre-sintering powder, the starting materials were Li _6.5 La ₃ (Zr _1.5 Nb _0.5 ) O ₁₂ , Li _6.625 La ₃ (Zr _1.625 Nb _0.375 ) O ₁₂ , Li _6.875 La ₃ (Zr _1.875 Nb _{0.125, respectively.} ) was obtained the sintered powder before and weighed so that the stoichiometric ratio of O _12. Each of the pre-sintered powders thus obtained was molded and then subjected to main sintering using an alumina firing container to obtain a garnet-type lithium ion conductive oxide. Since each oxide uses an alumina firing container, it contains Al, and at least a part of the Al exists in the crystal lattice or exists at the grain boundary between the particles. The 25 ° C. conductivity of each oxide was measured and found to be 3 × 10 ⁻⁴ S / cm, 4.5 × 10 ⁻⁴ S / cm, and 6 × 10 ⁻⁴ S / cm, respectively. Moreover, when activation energy was computed, all were 0.34 or less.

  The present invention can be used for an all solid-state lithium ion secondary battery.

Claims (7)

Li _x Ln ₃ (M ¹ _y M ² _z ) O _t (1)
(In the formula (1), Ln is one or more elements selected from the group consisting of La, Pr, Nd, Sm, Lu, Y, K, Mg, Ba, Ca, Sr,
M ¹ is one or more elements selected from the group consisting of Si, Sc, Ti, V, Ga, Ge, Y, Zr, Nb, In, Sb, Te, Hf, Ta, W, Bi,
M ² is an element different from M ^1, and one or more elements selected from the group consisting of Sc, Ti, V, Y, Nb, Hf, Ta, Si, Ga, and Ge,
x is a number satisfying 3 ≦ x ≦ 8,
y and z are numbers satisfying y> 0, z ≧ 0, 1.9 ≦ y + z ≦ 2.1,
t is a number satisfying 11 ≦ t ≦ 13)
Al is contained in the skeleton represented by the formula, and Al is contained in the crystal lattice of the Li _x Ln ₃ (M ¹ _y M ² _z ) O _t and the Li _x Ln ₃ (M ¹ _y M ² _z ) O. present in at least one of the grain boundaries between the grains of _t ,
Garnet type lithium ion conductive oxide.   The garnet-type lithium ion conductive oxide according to claim 1, wherein Al is contained in an amount of 0.07 mol to 0.25 mol with respect to 3 mol of Ln. The garnet-type lithium ion conductive oxide according to claim ¹ , wherein Ln is La, M ¹ is Zr, and x satisfies 5 ≦ x ≦ 7. The garnet-type lithium ion conductive oxide according to any one of claims 1 to 3, wherein M ² is Nb. A method for producing the garnet-type lithium ion conductive oxide according to any one of claims 1 to 4,
(A) Each starting material containing each element of formula (1) is weighed so as to have a stoichiometric ratio of formula (1), and the mixed powder is calcined, and then the calcined powder is A step of obtaining a pre-sintering powder by adding and mixing a lithium compound in order to make up for the loss of Li in the main sintering, and calcining the mixed powder again;
(B) The garnet-type lithium ion conductive oxide according to any one of claims 1 to 4 is obtained by forming the pre-sintered powder and then performing main sintering in an alumina firing container. Process,
Of a garnet-type lithium ion conductive oxide containing A method for producing the garnet-type lithium ion conductive oxide according to any one of claims 1 to 4,
(A) Each starting material containing each element of formula (1) is weighed so as to have a stoichiometric ratio of formula (1), and the mixed powder is calcined, and then the calcined powder is A step of obtaining a pre-sintering powder by adding and mixing a lithium compound in order to make up for the loss of Li in the main sintering, and calcining the mixed powder again;
(B) The garnet mold according to any one of claims 1 to 4, wherein a compound having an Al element is added to the pre-sintered powder, and the added powder is molded and then subjected to main sintering. Obtaining a lithium ion conductive oxide;
Of a garnet-type lithium ion conductive oxide containing Alumina is used as the compound having the Al element.
The manufacturing method of the garnet-type lithium ion conductive oxide of Claim 6.