JP7283122B2 - Garnet-type solid electrolyte, method for producing garnet-type solid electrolyte, secondary battery, electronic device - Google Patents

Description

The present invention relates to a garnet-type solid electrolyte, a method for producing a garnet-type solid electrolyte, a secondary battery using the solid electrolyte, and an electronic device equipped with the secondary battery.

As a secondary battery using a solid electrolyte, for example, Patent Document 1 discloses a positive electrode having a positive electrode active material that absorbs and releases lithium, a negative electrode that has a negative electrode active material that absorbs and releases lithium, and a positive electrode and a negative electrode. A lithium secondary battery is disclosed in which there is a lithium-conducting electrolyte interposed therebetween, and a lithium-ion-conducting garnet-type oxide in at least one of the positive electrode, the negative electrode, and the electrolyte. The garnet-type oxide has a composition formula of Li _5+x La ₃ (Zr _x A _2-x )O ₁₂ (wherein A is Sc, Ti, V, Nb, Hf, Ta, Al, Si, Ga and Ge At least one element selected from the group consisting of x and 1.4≤x≤2) is shown to be a solid electrolyte. In addition, an example in which the positive electrode contains a garnet-type oxide is shown, and by providing such a positive electrode, it is possible to improve the charge-discharge cycle characteristics and high-temperature stability of the lithium secondary battery. .

_The aforementioned Patent _Document 1 exemplifies _{a method} for producing a garnet-type oxide in which the _element A is Nb. Synthesis is performed using it as a raw material. Specifically, the starting materials are weighed based on the stoichiometric ratio in the above composition formula of the garnet-type oxide, and mixed and pulverized. The obtained mixed powder of starting materials is calcined in a crucible at 950° C. for 10 hours in an air atmosphere. Further, the mixed powder to which Li ₂ CO ₃ is excessively added is calcined again at 950° C. for 10 hours in an air atmosphere. Then, after molding, the garnet-type oxide is produced by firing in the atmosphere at 1200° C. for 36 hours.

JP 2011-113655 A

In the method for producing a garnet-type oxide, which is a solid electrolyte, disclosed in Patent Document 1, after calcination, main calcination is performed at a high temperature of 1200 ° C. exceeding 1000 ° C. for a long time, so that lithium volatilizes. As a result, the composition of the oxide changes, making it difficult to achieve the desired lithium ion conductivity.

The garnet-type solid electrolyte of the present application is represented by the composition formula Li7 _{-yLa3 ( Zr2 - xySnxMy} ) _O12 , where M is one or more selected from Ta, Sb, and Nb. and is characterized by satisfying 0.1≦x<0.5 and 0.1≦y≦0.7.
The garnet-type solid electrolyte of the present application refers to a solid electrolyte having a garnet-type crystal structure or a garnet-like crystal structure.

In the garnet-type solid electrolyte described above, M is one metal element selected from Ta, Sb, and Nb, and when M is Ta, 0.1 ≤ y ≤ 0.2 is satisfied. , when M is Sb, 0.3≦y≦0.5, and when M is Nb, 0.15≦y≦0.3.

In the garnet-type solid electrolyte described above, M is preferably two or more metal elements selected from Ta, Sb, and Nb.

A method for producing a garnet-type solid electrolyte _of the present application is a method for producing a garnet-type solid electrolyte represented by the following composition formula (1), wherein Li7 _{-yLa3 ( Zr2-xySnxMy )} O ₁₂ (1) M is one or more metal elements selected from Ta, Sb, and Nb, and satisfies 0.1≦x<0.5 and 0.1≦y≦0.7; and a lithium raw material solution in which a lithium compound containing 1.05 times or more and 1.2 times or less of lithium with respect to the stoichiometric composition of the composition formula (1) is dissolved, and the stoichiometric composition of the composition formula (1) A lanthanum raw material solution in which a lanthanum compound containing lanthanum in an amount equal to the composition is dissolved, and a zirconium raw material solution in which a zirconium compound containing zirconium in an amount equal to the stoichiometric composition of the composition formula (1) is dissolved; A tin raw material solution in which a tin compound containing tin is dissolved in an amount equivalent to the stoichiometric composition of the composition formula (1), and a metal element M equivalent to the stoichiometric composition of the composition formula (1). A metal raw material solution in which a metal compound containing the and a step of subjecting the oxide to a third heat treatment to sinter the oxide.

In the method for producing a garnet-type solid electrolyte described above, the heating temperature of the first heat treatment is 50° C. or higher and 250° C. or lower, and the heating temperature of the second heat treatment is 400° C. or higher and 550° C. or lower. The heating temperature of the third heat treatment is preferably 800° C. or higher and 950° C. or lower.

The secondary battery of the present application includes a positive electrode mixture containing the garnet-type solid electrolyte described above and a positive electrode active material containing lithium, an electrode provided on one surface of the positive electrode mixture, and a positive electrode mixture. and a current collector provided on the other surface.

In the secondary battery described above, the positive electrode active material is preferably a lithium composite metal oxide.

In the secondary battery described above, the electrode is preferably metallic lithium.

An electronic device according to the present application includes the secondary battery described above.

1 is a schematic perspective view showing the configuration of a lithium ion battery as a secondary battery of the first embodiment; FIG. 1 is a schematic cross-sectional view showing the structure of a lithium ion battery as a secondary battery of the first embodiment; FIG. 4 is a flowchart showing a method for producing a garnet-type solid electrolyte according to the first embodiment; 4 is a flow chart showing a method for manufacturing the lithium ion battery of the first embodiment; Schematic which shows the process in the manufacturing method of the lithium ion battery of 1st Embodiment. Schematic which shows the process in the manufacturing method of the lithium ion battery of 1st Embodiment. The perspective view which shows the structure of the wearable apparatus as an electronic device of 2nd Embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each of the following figures, the portions to be explained are displayed by being enlarged or reduced appropriately so that they are recognizable.

1. First Embodiment 1-1. Secondary Battery First, a secondary battery using the garnet-type solid electrolyte of the present embodiment will be described with reference to FIGS. 1 and 2, taking a lithium ion battery as an example. FIG. 1 is a schematic perspective view showing the configuration of a lithium ion battery as the secondary battery of the first embodiment, and FIG. 2 is a schematic cross-sectional view showing the structure of the lithium ion battery as the secondary battery of the first embodiment.

As shown in FIG. 1, a lithium ion battery 100 as a secondary battery of the present embodiment includes a positive electrode mixture 10 functioning as a positive electrode, an electrolyte layer 20 laminated in order on the positive electrode mixture 10, and a negative electrode 30. and have It also has a current collector 41 in contact with the positive electrode mixture 10 and a current collector 42 in contact with the negative electrode 30 . Since the positive electrode mixture 10, the electrolyte layer 20, and the negative electrode 30 are all composed of a solid phase, the lithium ion battery 100 of this embodiment is a chargeable/dischargeable all-solid secondary battery.

The lithium-ion battery 100 of the present embodiment is, for example, disk-shaped, and has a diameter Φ of, for example, 10 to 20 mm and a thickness of, for example, approximately 0.3 mm. Since it is small and thin, can be charged and discharged, and is all-solid, it can be suitably used as a power source for mobile information terminals such as smartphones. The size and thickness of the lithium ion battery 100 are not limited to these values as long as they can be molded. The thickness from the positive electrode mixture 10 to the negative electrode 30 when the external size is 10 to 20 mmφ as in the present embodiment is about 0.1 mm from the viewpoint of moldability when it is thin, and when it is thick, it is good for lithium ion conductivity. It is estimated from the point of view, and the thickness is up to about 1 mm. In addition, the shape of the lithium ion battery 100 is not limited to a disc shape, and may be a polygonal disc shape. Hereinafter, each configuration will be described in detail.

1-1-1. Positive Electrode Mixed Material As shown in FIG. 2, the positive electrode mixed material 10 includes a particulate positive electrode active material 11 and a garnet-type solid electrolyte 12 of the present embodiment. The garnet-type solid electrolyte 12 fills the gaps generated by the contact of the particulate positive electrode active materials 11 with each other. The garnet-type solid electrolyte 12 is hereinafter simply referred to as the solid electrolyte 12 .

Any material may be used as the positive electrode active material 11 of the present embodiment as long as it is capable of repeatedly intercalating and deintercalating lithium ions electrochemically. Specifically, it contains at least lithium (Li) and is selected from vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu). It is preferable to use a lithium mixed metal oxide containing at least one selected transition metal as a constituent element because it is chemically stable. Examples of such lithium _{composite metal oxides include LiCoO2, LiNiO2, LiMn2O4, Li2Mn2O3, NMC (Li(NixMnyCo1 - xy ) O2 [ 0 < x + y} <1]) _, NCA (Li( _{NixCoyAl1 -xy ) O2} [ ₀ <x+y< _{1 ]} ), LiCr0.5Mn0.5O2, _LiFePO4 , _Li2FeP2O7 , _{LiMnPO4 ,} LiFeBO ₃ , _{Li3V2 ( PO4} ) ₃ , _{Li2CuO2 , Li2FeSiO4 , Li2MnSiO4} and the like _. Lithium mixed metal oxides also include solid solutions in which some atoms in the crystal of these lithium mixed metal oxides are substituted with typical metals, alkali metals, alkaline earth metals, lanthanides, chalcogenides, halogens, etc. , these solid solutions can also be used as the positive electrode active material 11 . In the present embodiment, particles of LiCoO ₂ are used as the positive electrode active material 11 because high lithium ion conductivity can be obtained.

From the viewpoint of bringing the particles of the positive electrode active material 11 into contact with each other to exhibit electron conductivity, the particle size of the positive electrode active material 11 is preferably, for example, 500 nm or more and less than 10 μm in average particle size D50. In FIG. 2, the particle shape of the positive electrode active material 11 is assumed to be spherical, but the actual particle shape is not necessarily spherical and has an irregular shape.

A detailed method for forming the positive electrode mixture 10 will be described later, but in addition to the green sheet method, a press sintering method and the like can be mentioned. When using the green sheet method or the press sintering method, if the solid electrolyte 12 is present between the particles of the positive electrode active material 11 after sintering, the contact area between the particulate positive electrode active material 11 and the solid electrolyte 12 increases. , the interfacial impedance of the positive electrode mixture 10 can be reduced. Since the lithium ion battery 100 of the present embodiment is small and thin, considering the interfacial impedance of the positive electrode mixture 10, the bulk density of the positive electrode active material 11 in the positive electrode mixture 10 is 40% to 60%. is preferred, and the bulk density of the solid electrolyte 12 is also preferably 40% to 60%. The solid electrolyte 12 of the present embodiment will be described in detail later, but the solid electrolyte 12 uses a garnet-type lithium composite metal oxide that conducts lithium, and has a particulate shape with an average particle size smaller than that of the positive electrode active material 11. It has become. Therefore, interfacial impedance, that is, grain boundary resistance exists between the solid electrolyte particles constituting the solid electrolyte 12. However, since the average particle size is small, the grain boundary resistance is low, and electric charges are easily transferred. It is in an easy state.

In order to obtain excellent charge/discharge characteristics in the lithium ion battery 100, the positive electrode mixture 10 is required to have high lithium ion conductivity. Therefore, not only the selection of the material for the positive electrode active material 11 but also the composition of the solid electrolyte 12 to form the positive electrode mixture 10 is an important issue. In this embodiment, a garnet-type lithium composite metal oxide that can be sintered at a low temperature and has high lithium ion conductivity is used as the solid electrolyte 12 .

1-1-2. Garnet-Type Solid Electrolyte The solid electrolyte 12 of the present embodiment is a lithium composite metal oxide having a garnet-type crystal structure or a garnet-like crystal structure that conducts lithium represented by the following compositional formula (1).
Li7 _{-yLa3 (} Zr2 _{-xySnxMy ) O12} ( ₁ )
M is one or more metal elements selected from Ta, Sb, and Nb, and satisfies 0.1≦x<0.5 and 0.1≦y≦0.7.

In "Chemicals of Materials," published by the American Chemical Society and issued April 30, 2015, Lincoln J. et al. Miara, William Davidson Richards, Yan E.; According to the article "First-Principles studies on catation dopants and electron/cathode interfaces for lithium garnets" submitted by Wang and Gerbrand Ceder, an element (Dopan t) as Mg, Sc, Ti, Hf, V, Nb, Ta, Ce, Th, Cr, Mo, W, Pa, Mn, Tc, Ru, Np, Co, Rh, Ir, Pu, Ni, Pd, Pt, Eu, Cu, Au, Cd, Hg, In, Tl, C, Si, Ge, Sn, Pb, As, Sb, S, Se, Te, Cl, I are mentioned. In this embodiment, Sn is selected from these elements from the viewpoint of lowering the temperature of sintering of the oxide in the solid electrolyte 12 . In addition, from the viewpoint of realizing high lithium ion conductivity in the solid electrolyte 12, these elements have a large dielectric constant and a small vacancy generation energy (E _defect (eV)), so that the Zr site can be relatively easily formed. Substitutable Ta, Sb, and Nb are selected.

According to such a lithium composite metal oxide, some of the zirconium (Zr) sites in the crystal structure are selected from tin (Sn), tantalum (Ta), antimony (Sb), and niobium (Nb). By substituting with one or more kinds of metal elements M, it is possible to sinter the oxide at a firing temperature of 950 ° C. or less in the method for manufacturing the solid electrolyte 12 described later, and to realize high lithium ion conductivity. can be done.

From the viewpoint of realizing a low temperature in oxide sintering and a high lithium ion conductivity in the solid electrolyte 12, the value x of the stoichiometric composition ratio of Sn in the above composition formula (1) is 0.1≦ A range of x<0.5 is preferred. When x is less than 0.1, it becomes difficult to lower the temperature in sintering the oxide. When x is 0.5 or more, the lithium ion conductivity decreases. Also, if the value y of the stoichiometric composition ratio of the metal element M in the above composition formula (1) is less than 0.1 or exceeds 0.7, the lithium ion conductivity is lowered. Details will be described in the sections of examples and comparative examples of the solid electrolyte 12 described later.

1-1-3. Negative Electrode The negative electrode 30 as an electrode provided on the one surface 10b side of the positive electrode mixture 10 of the present embodiment contains a negative electrode active material. As the negative electrode active material, any material may be used as long as it is capable of repeatedly intercalating and deintercalating lithium ions electrochemically at a potential lower than that of the material selected as the positive electrode active material 11 . Specifically, Nb ₂ O ₅ , V ₂ O ₅ , TiO ₂ , In ₂ O ₃ , ZnO, SnO ₂ , NiO, ITO (Indium Tin Oxide), AZO (Al-doped Zinc Oxide), FTO (F- doped Tin Oxide), anatase phase of TiO ₂ , lithium composite metal oxides such as Li ₄ Ti ₅ O ₁₂ , Li ₂ Ti ₃ O ₇ , Li, Si, Sn, Si--Mn, Si--Co, Si--Ni, Examples include metals such as In and Au, alloys containing these metals, carbon materials, and substances in which lithium ions are inserted between layers of carbon materials. The alloy is not particularly limited as long as it is capable of intercalating and deintercalating lithium, but it preferably contains a metal or metalloid element other than carbon of groups 13 and 14, more preferably aluminum, silicon and tin. It is an alloy or compound containing these atoms. These may be used alone, or two or more of them may be used in any combination and ratio. The alloys include lithium alloys such as Li--Al, Li--Ni, Li--Si, Li--Sn and Li--Sn--Ni, silicon alloys such as Si--Zn, Sn--Mn, Sn--Co, Sn--Ni, Tin alloys such as Sn--Cu and Sn--La, Cu ₂ Sb, La ₃ Ni ₂ Sn ₇ and the like can be exemplified.
Considering the discharge capacity of the small and thin lithium ion battery 100 of the present embodiment, the negative electrode 30 is preferably made of metal lithium (metal Li) or a single metal or alloy forming a lithium alloy.

The method for forming the negative electrode 30 using the negative electrode active material includes a solution process such as a so-called sol-gel method and an organometallic thermal decomposition method that involve a hydrolysis reaction of an organometallic compound, and a CVD method in a suitable metal compound and gas atmosphere. , ALD method, green sheet method and screen printing method using slurry of solid negative electrode active material, aerosol deposition method, sputtering method using appropriate target and gas atmosphere, PLD method, vacuum deposition method, plating method, thermal spraying method etc., may be used. In this embodiment, the negative electrode 30 is formed by forming a film of metal Li on the electrolyte layer 20 by a sputtering method.

1-1-4. Electrolyte Layer As shown in FIG. 2 , an electrolyte layer 20 is provided between the positive electrode mixture 10 and the negative electrode 30 . When metal Li is used as the negative electrode 30 as described above, lithium ions are released from the negative electrode 30 when the lithium ion battery 100 is discharged. When the lithium ion battery 100 is charged, lithium ions are deposited as metal on the negative electrode 30 to form dendrites called dendrites. When dendrites grow and come into contact with the positive electrode active material 11 of the positive electrode mixture 10 , the positive electrode mixture 10 functioning as a positive electrode and the negative electrode 30 are short-circuited. In order to prevent this short circuit, an electrolyte layer 20 is provided between the positive electrode mixture 10 and the negative electrode 30 . The electrolyte layer 20 is a layer made of an electrolyte that does not contain the positive electrode active material 11 . The electrolyte layer 20 can be crystalline or amorphous made of metal compounds such as oxides, sulfides, halides, nitrides, hydrides and borides.

Examples of oxide crystals include Li _0.35 La _0.55 TiO ₃ , Li _0.2 La _0.27 NbO ₃ , and some of the elements of these crystals are N, F, Al, Sr, Sc, Nb, Ta, Sb, and lanthanoid elements. Perovskite-type crystals or perovskite-like _{crystals substituted with, for example, Li7La3Zr2O12, Li5La3Nb2O12 , Li5BaLa2TaO12 , and some of} the elements _{of these crystals} are N _, F , Al, Sr, Sc, Nb, Ta, Sb, garnet-type crystals or garnet-like crystals substituted with lanthanoid elements, Li _1.3 Ti _1.7 Al _0.3 (PO ₄ ) ₃ , Li _1.4 Al _0.4 Ti _1.6 (PO ₄ ) ₃ , Li _1.4 Al _0.4 Ti _1.4 Ge _0.2 (PO ₄ ) ₃ , and NASICON-type crystals obtained by substituting part of these crystals with N, F, Al, Sr, Sc, Nb, Ta, Sb, lanthanide elements, etc., Li LISICON-type crystals such as ₁₄ ZnGe ₄ O ₁₆ , other crystals such as Li _3.4 V _0.6 Si _0.4 O ₄ , Li _3.6 V _0.4 Ge _0.6 O ₄ , Li _2+x C _1-x B _x O ₃ , etc. can be mentioned.

_{Examples of sulfide crystals} include _{Li10GeP2S12 , Li9.6P3S12 , Li9.54Si1.74P1.44S11.7Cl0.3 , and Li3PS4 .}

Examples of other amorphous materials include Li ₂ O--TiO ₂ , La ₂ O ₃ --Li ₂ O--TiO ₂ , LiNbO ₃ , LiSO ₄ , Li ₄ SiO ₄ , Li ₃ PO ₄ --Li ₄ SiO ₄ , _{Li4GeO4 - Li3VO4 , Li4SiO4 -Li3VO4 , Li4GeO4 - Zn2GeO2 , Li4SiO4 - LiMoO4 , Li4SiO4 - Li4ZrO4 , SiO2} - _P2O5 - _Li2O , _SiO2 - _P2O5 - _{LiCl , Li2O -} LiCl- _{B2O3 , LiAlCl4} , _LiAlF4 , LiF- _Al2O3 , LiBr- _Al2 O ₃ , Li _2.88 PO _3.73 N _0.14 , Li ₃ N--LiCl, Li ₆ NBr ₃ , Li ₂ S--SiS ₂ , Li ₂ S--SiS ₂ --P ₂ S ₅ and the like.

Note that the electrolyte layer 20 may be configured using the garnet-type lithium composite metal oxide that configures the solid electrolyte 12 described above. When the electrolyte layer 20 is crystalline, it preferably has a crystal structure such as a cubic crystal with small crystal plane anisotropy in the direction of lithium ion conduction. Moreover, when amorphous, the anisotropy of lithium ion conduction is small.

The thickness of the electrolyte layer 20 is preferably 0.1 μm or more and 100 μm or less, more preferably 0.2 μm or more and 10 μm or less. By setting the thickness of the electrolyte layer 20 within the above range, the internal resistance of the electrolyte layer 20 can be reduced, and the occurrence of a short circuit between the positive electrode mixture 10 and the negative electrode 30 can be suppressed.

The surface of the electrolyte layer 20 in contact with the negative electrode 30 may be provided with an uneven structure such as trenches, gratings, and pillars by combining various molding methods and processing methods as necessary.

1-1-5. Current Collector As shown in FIG. 2 , the lithium ion battery 100 has a current collector 41 in contact with the other surface 10 a of the positive electrode mixture 10 and a current collector 42 in contact with the negative electrode 30 . The current collectors 41 and 42 are conductors provided to transfer electrons to and from the positive electrode mixture 10 or the negative electrode 30, have sufficiently low electrical resistance, and change their electrical conductivity characteristics and mechanical structure due to charging and discharging. Materials that do not are selected. For example, copper (Cu), magnesium (Mg), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), indium (In ), gold (Au), platinum (Pt), silver (Ag), and palladium (Pd), one metal (elemental metal) selected from the metal group, or two or more metals selected from the metal group alloys, etc., are used.

In this embodiment, aluminum (Al) is used as the current collector 41 on the positive electrode mixture 10 side, and copper (Cu) is used as the current collector 42 on the negative electrode 30 side. The thickness of each of the current collectors 41 and 42 is, for example, 20 μm to 40 μm. Note that the lithium ion battery 100 may include one of the pair of current collectors 41 and 42 . For example, when a plurality of lithium-ion batteries 100 are stacked so as to be electrically connected in series, the lithium-ion battery 100 may include only the current collector 41 of the pair of current collectors 41 and 42. It is also possible to

1-2. Method for Producing Garnet-Type Solid Electrolyte Next, a method for producing the garnet-type solid electrolyte 12 of the present embodiment will be described with reference to FIG. FIG. 3 is a flow chart showing a method for producing a garnet-type solid electrolyte according to this embodiment.

As shown in FIG. 3, the method for producing the garnet-type solid electrolyte 12 of the present embodiment comprises a step of preparing a raw material solution containing elements represented by the following compositional formula (1) (step S1); A step of mixing the raw material solution and applying a first heat treatment to remove the solvent to form a mixture (step S2), and a step of applying a second heat treatment to the mixture to form a calcined body (step S3 ), and a step of subjecting the calcined body to a third heat treatment and finally calcining it (step S4).
Li7 _{-yLa3 (} Zr2 _{-xySnxMy ) O12 (} 1)
M is one or more metal elements selected from Ta, Sb, and Nb, and satisfies 0.1≦x<0.5 and 0.1≦y≦0.7.

In step S1, a raw material solution containing Li, La, Zr, Sn, and metal element M, which are elements contained in the above composition formula (1), is prepared for each element. Specifically, the raw material solution is adjusted so that 1 mol (mol) of the element is contained per 1 kg of the raw material solution. Sources of elements in the raw material solution are lithium compounds, lanthanum compounds, zirconium compounds, tin compounds, metal compounds, including metal element M, which can be dissolved in a single solvent or mixed solvent of water and organic solvents. These element compounds are preferably metal salts or metal alkoxides of the elements.

Lithium compounds (lithium sources) include, for example, lithium metal salts such as lithium chloride, lithium nitrate, lithium acetate, lithium hydroxide, lithium carbonate, lithium methoxide, lithium ethoxide, lithium propoxide, lithium isopropoxide, lithium Lithium alkoxides such as butoxide, lithium isobutoxide, lithium secondary butoxide, lithium tertiary butoxide, and dipivaloylmethanatritium can be mentioned, and one or more of these can be used in combination.

Lanthanum compounds (lanthanum sources) include, for example, lanthanum metal salts such as lanthanum chloride, lanthanum nitrate and lanthanum acetate, lanthanum trimethoxide, lanthanum triethoxide, lanthanum tripropoxide, lanthanum triisopropoxide, lanthanum tributoxide, Lanthanum alkoxides such as lanthanum triisobutoxide, lanthanum trisecondary butoxide, lanthanum tritertiary butoxide, and dipivaloylmethanatrantanane can be mentioned, and one or more of these can be used in combination.

Zirconium compounds (zirconium sources) include, for example, zirconium metal salts such as zirconium chloride, zirconium oxychloride, zirconium oxynitrate, zirconium oxyacetate and zirconium acetate, zirconium tetramethoxide, zirconium tetraethoxide, zirconium tetrapropoxide, zirconium zirconium alkoxides such as tetraisopropoxide, zirconium tetrabutoxide, zirconium tetraisobutoxide, zirconium tetra-secondary butoxide, zirconium tetra-tertiary butoxide, and dipivaloylmethanatozirconium; They can be used in combination.

Tin compounds (tin sources) include, for example, stannic chloride, stannic bromide, stannous fluoride, stannic iodide, tin sulfide, stannous acetate, and stannous oxalate. Metal salts, tin alkoxides such as tin tetraethoxide, tin tetraisopropoxide, tin tetra-normal butoxide and the like can be mentioned, and one or more of these can be used in combination.

Metal element M is selected from Ta, Sb, and Nb. Therefore, when the metal element M is tantalum (Ta), examples of tantalum compounds (tantalum sources) include tantalum metal salts such as tantalum chloride and tantalum bromide, tantalum pentamethoxide, tantalum pentaethoxide, tantalum pentaiso tantalum alkoxides such as propoxide, tantalum penta-normal propoxide, tantalum pentaisobutoxide, tantalum penta-normal butoxide, tantalum penta-secondary butoxide, tantalum penta-tertiary butoxide, and the like, one or more of these in combination can be used.

When the metal element M is antimony (Sb), antimony compounds (antimony sources) include, for example, antimony metal salts such as antimony bromide, antimony chloride, antimony fluoride, antimony trimethoxide, antimony triethoxide, antimony Antimony alkoxides such as triisopropoxide, antimony tri-normal propoxide, antimony tri-isobutoxide, and antimony tri-normal butoxide can be mentioned, and one or more of these can be used in combination.

When the metal element M is niobium (Nb), examples of niobium compounds (niobium sources) include niobium metal salts such as niobium chloride, niobium oxychloride, and niobium oxalate, niobium pentaethoxide, niobium pentapropoxide, niobium Examples include niobium alkoxides such as pentaisopropoxide and niobium pentasecondary butoxide, and niobium pentaacetylacetonate, and one or more of these can be used in combination.

The organic solvent constituting the single solvent or mixed solvent is not particularly limited, but examples include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, allyl alcohol, ethylene glycol monobutyl ether (2- n-butoxyethanol) and other alcohols, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, pentanediol, hexanediol, heptanediol, dipropylene glycol and other glycols, dimethyl ketone, methyl ethyl ketone, methyl propyl ketone, methyl Ketones such as isobutyl ketone, esters such as methyl formate, ethyl formate, methyl acetate, methyl acetoacetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, dipropylene glycol Ethers such as monomethyl ether, organic acids such as formic acid, acetic acid, 2-ethylbutyric acid and propionic acid, aromatics such as toluene, o-xylene and p-xylene, formamide, N,N-dimethylformamide, N,N - Amides such as diethylformamide, dimethylacetamide and N-methylpyrrolidone.

In step S2, the at least five raw material solutions prepared in step S1 are mixed according to the composition ratio of the elements in the composition formula (1) described above to prepare a mixed solution. Then, the mixed solution is subjected to a first heat treatment at 50° C. to 250° C. to evaporate the solvent and form a mixture. In addition, the amount of the raw material solution of the lithium compound in the mixed solution is the chemical amount represented by the composition formula (1), considering the amount of lithium volatilized and lost in the third heat treatment of the main firing performed after this. It is preferable to increase the amount by 1.05 times or more and 1.2 times or less with respect to the theoretical composition. The amount of each raw material solution of a lanthanum compound, a zirconium compound, a tin compound, and a metal compound containing the metal element M other than the lithium compound is equal to the stoichiometric composition represented by the composition formula (1). .

In step S3, the mixture obtained in step S2 is subjected to a second heat treatment (temporary baking) at 400° C. or higher and 550° C. or lower to completely remove the solvent from the mixture and oxidize it, and the oxide is calcined. form the body. The heating time for calcination is 30 minutes to 2 hours.

In step S4, the calcined body obtained in step S3 is subjected to a third heat treatment at 800° C. or higher and 950° C. or lower for main sintering. The heating time in the main firing is 4 hours to 10 hours. By the main firing, the calcined oxide body is sintered to obtain the garnet-type crystalline solid electrolyte 12 represented by the following compositional formula (1).
Li7 _{-yLa3 (} Zr2 _{-xySnxMy ) O12 (} 1)
M _y is one or more metal elements selected from Ta, Sb, and Nb, and satisfies 0.1≦x<0.5 and 0.1≦y≦0.7.

1-3. Method for Manufacturing Lithium Ion Battery Next, an example of a method for manufacturing the lithium ion battery 100 of the present embodiment will be described with reference to FIGS. 4 to 6. FIG. FIG. 4 is a flowchart showing the method for manufacturing the lithium ion battery of the first embodiment, and FIGS. 5 and 6 are schematic diagrams showing steps in the method for manufacturing the lithium ion battery of the first embodiment.

As shown in FIG. 4, an example of a method for manufacturing the lithium ion battery 100 of the present embodiment includes a step of forming a sheet of a mixture containing the positive electrode active material 11 and the solid electrolyte 12 of the present embodiment (step S11); The method includes a step of forming a molded article using a mixture sheet (step S12) and a step of firing the molded article (step S13). Steps S11 to S13 up to this point are the steps showing the manufacturing method of the positive electrode mixture 10 . Then, the step of forming the electrolyte layer 20 (step S14), the step of forming the negative electrode 30 (step S15), and the step of forming the current collectors 41 and 42 (step S16).

In the mixture sheet forming process of step S11, first, the particulate positive electrode active material 11, the pulverized solid electrolyte 12, the solvent, and the binder are mixed to prepare a slurry 10m as a mixture. The mass ratio of each material in the slurry 10m is, for example, 40% positive electrode active material 11, 10% binder, 40% solid electrolyte 12, and the remainder solvent. Next, a sheet 10s is formed using the slurry 10m. Specifically, as shown in FIG. 5, for example, using a fully automatic film applicator 400, a sheet 10s is formed by applying 10m of slurry to a constant thickness on a substrate 406 such as a polyethylene terephthalate (PET) film. . A fully automatic film applicator 400 has an application roller 401 and a doctor roller 402 . A squeegee 403 is provided to contact the doctor roller 402 from above. A conveying roller 404 is provided at a position below the coating roller 401 to face it. direction. 10 m of slurry is put on the side where the squeegee 403 is provided between the coating roller 401 and the doctor roller 402 which are arranged with a gap in the conveying direction of the stage 405 . The coating roller 401 and the doctor roller 402 are rotated so as to push the slurry 10m downward through the gap, and the surface of the coating roller 401 is coated with the slurry 10m with a constant thickness. At the same time, the transport roller 404 is rotated, and the stage 405 is transported so that the substrate 406 contacts the application roller 401 coated with the slurry 10m. As a result, the slurry 10m applied to the application roller 401 is transferred to the base material 406 in the form of a sheet to form a sheet 10s. The thickness of the sheet 10s at this time is, for example, 175 μm to 225 μm. In the process of forming the sheet 10s in step S11, the slurry 10m is applied by the application roller 401 and the doctor roller 402 so that the volume density of the positive electrode active material 11 in the positive electrode mixture 10 obtained after firing is 50% or more. A sheet 10s having a constant thickness is obtained by pressurizing and extruding.

Next, by heating the substrate 406 on which the sheet 10s is formed, the solvent is removed from the sheet 10s and the sheet 10s is cured. Then, the process proceeds to step S12.

In the step S12 of forming the molded product, a die corresponding to the shape of the positive electrode mixture 10 is used to punch out the sheet 10s, thereby taking out a disk-shaped molded product 10f as shown in FIG. . A plurality of moldings 10f can be taken out from one sheet 10s. Then, the process proceeds to step S13.

In step S13, the molding sintering step, the molding 10f is placed in a crucible made of, for example, magnesium oxide, placed in an electric muffle furnace, and fired at a temperature below the melting point of the positive electrode active material 11 to sinter the molding 10f. do. By firing, the binder is removed, and the positive electrode mixture 10 is obtained in which the positive electrode active materials 11 are sintered while being in contact with each other. In the cathode mixture 10, the solid electrolyte 12 exists between the particulate cathode active materials 11 that are in contact with each other (see FIG. 2). The thickness of the positive electrode mixture 10 obtained after sintering is approximately 150 μm to 200 μm. Then, the process proceeds to step S14.

In the electrolyte layer forming step of step S<b>14 , the electrolyte layer 20 is formed on the positive electrode mixture 10 . In this embodiment, an amorphous electrolyte such as LIPON (Li _2.9 PO _3.3 N _0.46 ) is deposited by sputtering to form the electrolyte layer 20 . The thickness of the electrolyte layer 20 is, for example, 2 μm. Then, the process proceeds to step S15.

In the step S15 of forming the negative electrode, the negative electrode 30 is formed by laminating the electrolyte layer 20 . As described above, the negative electrode 30 can be formed by various methods such as a solution process. bottom. The thickness of the negative electrode 30 is, for example, 20 μm. Then, the process proceeds to step S16.

In the current collector forming step of step S16, as shown in FIG. Also, a current collector 42 is formed so as to be in contact with the negative electrode 30 . In this embodiment, for example, an aluminum foil having a thickness of 20 μm is used, and the current collector 41 is formed by placing the aluminum foil in pressure contact with the forming surface. Further, the current collector 42 is formed by using a copper foil having a thickness of 20 μm, for example, and placing the copper foil in pressure contact with the forming surface. As a result, a lithium ion battery 100 is obtained in which a laminate in which the positive electrode mixture 10, the electrolyte layer 20, and the negative electrode 30 are laminated in this order is sandwiched between the pair of current collectors 41 and 42. FIG. Note that the current collector 41 may be formed so as to be in contact with the positive electrode mixture 10 after step S13.

In the method of manufacturing the lithium ion battery 100 of the present embodiment, the method of forming the positive electrode mixture 10 by the green sheet method was exemplified, but the method of forming the positive electrode mixture 10 is not limited to this. For example, the powder obtained by putting the garnet-type solid electrolyte 12 of the present embodiment in an agate mortar and pulverizing it well, and the particulate positive electrode active material 11 are put into a pellet die with an exhaust port, and uniaxially press-molded. The molded product may be placed in a crucible, placed in an electric muffle furnace, and fired at a temperature lower than the melting point of the positive electrode active material 11 to obtain the positive electrode mixture 10 .

1-4. Examples of Solid Electrolyte Next, specific examples 1 to 17 of the solid electrolyte of the present embodiment will be given to explain specific manufacturing methods thereof.

First, the raw material solutions containing raw material elements used for the production of the solid electrolytes of Examples 1 to 17 are exemplified.

[2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg]
1.3789 g of 99.95% pure lithium nitrate (manufactured by Kanto Kagaku, 3N5) and 2-butoxyethanol (ethylene glycol 18.6211 g of monobutyl ether (manufactured by Kanto Chemical Co., Ltd., deer special grade) were weighed. Then, placed on a magnetic stirrer with a hot plate function, while stirring at 190 ° C. for 1 hour, lithium nitrate was completely dissolved in 2-butoxyethanol and slowly cooled to room temperature of about 20 ° C. to give a concentration of 1 mol / kg. of lithium nitrate in 2-butoxyethanol was obtained. The purity of lithium nitrate can be measured using an ion chromatography mass spectrometer.

[2-butoxyethanol solution of lanthanum nitrate hexahydrate with a concentration of 1 mol/kg]
8.6608 g of lanthanum nitrate hexahydrate (manufactured by Kanto Kagaku, 4N) and 11.3392 g of 2-butoxyethanol were weighed into a 30 g Pyrex reagent bottle containing a magnetic stir bar. Next, put it on a magnetic stirrer with a hot plate function, and while stirring at 140° C. for 30 minutes, completely dissolve lanthanum nitrate hexahydrate in 2-butoxyethanol and slowly cool it to room temperature of about 20° C. , to obtain a 2-butoxyethanol solution of lanthanum nitrate hexahydrate with a concentration of 1 mol/kg.

[Butanol solution of zirconium tetra-normal butoxide with a concentration of 1 mol/kg]
3.8368 g of zirconium tetra-normal butoxide (manufactured by Wako Pure Chemical Industries) and 6.1632 g of butanol (normal butanol) were weighed into a 20-g Pyrex reagent bottle containing a magnetic stir bar. Next, the zirconium tetra-normal butoxide was completely dissolved in butanol while being placed on a magnetic stirrer and stirred at room temperature of about 20° C. for 30 minutes to obtain a butanol solution of zirconium tetra-normal butoxide with a concentration of 1 mol/kg.

[2-butoxyethanol solution of tin tetraisopropoxide at a concentration of 1 mol/kg]
First, impurities contained in tin tetraisopropoxide (manufactured by Kojundo Chemical Laboratory Co., Ltd., 3N) are removed by adsorption to neutral silica (for example, Wakosil C-300 (manufactured by Fujifilm Wako Pure Chemical Industries)). Apply adsorption treatment. 3.5510 g of adsorbed tin tetraisopropoxide and 6.4490 g of 2-butoxyethanol were weighed into a 20 g Pyrex reagent bottle containing a magnetic stir bar. Next, the tin tetraisopropoxide was completely dissolved in 2-butoxyethanol while being placed on a magnetic stirrer with a hot plate function and stirred at 140°C for 30 minutes, and slowly cooled to room temperature of about 20°C. A 2-butoxyethanol solution of tin tetraisopropoxide with a concentration of 1 mol/kg was obtained.

[2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of 1 mol/kg]
5.4640 g of tantalum pentanormal butoxide (manufactured by Kojundo Chemical Laboratory, 5N) and 4.5360 g of 2-butoxyethanol were weighed into a 20 g Pyrex reagent bottle containing a magnetic stir bar. Then, the tantalum penta-normal butoxide was completely dissolved in 2-butoxyethanol while being placed on a magnetic stirrer and stirred at room temperature for 30 minutes to obtain a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of 1 mol/kg. rice field.

[2-butoxyethanol solution of antimony tri-normal butoxide with a concentration of 1 mol/kg]
3.4110 g of antimony trinormal butoxide (manufactured by Kojundo Chemical Laboratory, 5N) and 6.5890 g of 2-butoxyethanol were weighed into a 20 g Pyrex reagent bottle containing a magnetic stir bar. Next, the antimony tri-n-butoxide was completely dissolved in 2-butoxyethanol while being placed on a magnetic stirrer and stirred at room temperature for 30 minutes to obtain a 2-butoxyethanol solution of antimony tri-n-butoxide with a concentration of 1 mol/kg. rice field.

[1 mol/kg concentration of niobium pentaethoxide in 2-butoxyethanol solution]
3.1821 g of niobium pentaethoxide (manufactured by Kojundo Chemical Laboratory, 4N) and 6.8179 g of 2-butoxyethanol were weighed into a 20 g Pyrex reagent bottle containing a magnetic stir bar. Next, the niobium pentaethoxide was completely dissolved in 2-butoxyethanol while being placed on a magnetic stirrer and stirred at room temperature for 30 minutes to obtain a 2-butoxyethanol solution of niobium pentaethoxide with a concentration of 1 mol/kg. rice field.

1-4-1. _{Production of} Solid Electrolyte Pellets _{for Evaluation} of _{Example 1} A mixed solution was prepared using the above raw material solutions so as to have a value of 0.1. Specifically, first, in a titanium petri dish with an inner diameter of 50 mm and a height of 20 mm, 8.280 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol / kg, lanthanum nitrate hexahydrate with a concentration of 1 mol / kg. 3.000 g of 2-butoxyethanol solution, 1.600 g of butanol solution of zirconium tetra-normal butoxide with concentration of 1 mol/kg, 0.300 g of 2-butoxyethanol solution of tin tetraisopropoxide with concentration of 1 mol/kg, 1 mol/kg 0.100 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide having a concentration of kg was weighed and mixed at room temperature to obtain a mixed solution. The mass (g) of the 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg is set in consideration of the mass of Li that volatilizes during main firing at 950°C. Specifically, at the stage before the main firing, 8.280 g, which is 1.2 times the mass corresponding to Li _6.9 shown in the above composition formula when y = 0.1, is added at a concentration of 1 mol / kg. It is the mass of the 2-butoxy ethanol solution of lithium nitrate. Note that the rate of increase in the amount of the lithium source considering the mass of Li volatilized during main firing is not limited to 1.2 times, but depends on the firing temperature. For example, if the temperature in the third heat treatment during main firing is 800° C., the ratio of increase in lithium source may be 1.1 times. In addition, the volatilization amount of Li during main firing becomes saturated when the firing time exceeds 1 hour. Also, the amounts of the raw material solutions of the elements other than the lithium source are set to be equal to the stoichiometric composition of the above composition formula.

Next, the petri dish made of titanium was placed on a hot plate, and the set temperature of the hot plate was set to 160° C. and heated for 1 hour, followed by heating at 180° C. for 30 minutes to remove the solvent. Subsequently, the temperature of the hot plate was set to 360° C. and the mixture was heated for 30 minutes to decompose most of the contained organic components by combustion. After that, the temperature of the hot plate was set to 540° C. and heated for 1 hour to burn and decompose the remaining organic components. Then, it was slowly cooled to room temperature on a hot plate to obtain a calcined body. Next, the calcined body was transferred to an agate mortar and sufficiently pulverized. Weigh 0.150 g of the pulverized calcined body, put it in a die (molding mold) with an exhaust port having an inner diameter of 10 mm, and pressurize it for 5 minutes at a pressure of 624 MPa (megapascal) to obtain a disk-shaped molded product. A calcined body pellet was produced. Next, the calcined pellets were placed in a crucible made of magnesium oxide, covered with a lid made of magnesium oxide, and subjected to main calcination at 950° C. for 8 hours in an electric muffle furnace FP311 manufactured by Yamato Scientific Co., Ltd. The electric muffle furnace was slowly cooled to room temperature, and the calcined pellet was taken out to produce a solid electrolyte pellet for evaluation of Example 1 having a diameter of about 9.5 mm and a thickness of about 600 μm. The method of preparing the mixed solution of Example 1 and manufacturing the solid electrolyte pellet for evaluation follows steps S1 to S4 described above. The _composition formula showing the solid electrolyte pellet _{of Example} 1 is _Li6.9La3 ( _{Zr1.6Sn0.3Ta0.1} ) _O12 .

Thermogravimetric/differential thermal analysis (TG-DTA) was performed using the calcined pellets in Example 1 as a sample, and the formation temperature of tetragonal crystals was 714.4 ° C., and the tetragonal crystals changed to cubic crystals. The transition temperature was found to be 790.0°C. This _is because the transition _temperature from _{the tetragonal system} to the cubic system _is about 70°C lower. In other words, it indicates that the transition temperature from the tetragonal system to the cubic system is lowered by substituting a part of the Zr sites with Sn. Therefore, by adopting a composition in which a part of the Zr site is substituted with Sn, even if the temperature of the third heat treatment in the main firing is lower than 1000 ° C., for example, 950 ° C., the calcined body which is an oxide is sufficiently obtained. It can be sintered into a cubic garnet-type solid electrolyte that exhibits high lithium ion conductivity.

1-4-2. Production _{of Solid} Electrolyte _Pellets for _Evaluation of _{Example 2} A mixed solution was prepared using the raw material solution described above so that the value becomes 0.15. Specifically, first, 8.220 g of a 2-butoxyethanol solution of 1 mol/kg lithium nitrate and 1 mol/kg lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.550 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.150 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li volatilized during main firing, 8.220 g, which is 1.2 times the mass corresponding to Li _6.85 shown in the above composition formula when y = 0.15, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 2 was produced using the calcined body. The composition formula showing the solid electrolyte pellet _{of Example 2} is _Li6.85La3 ( _{Zr1.55Sn0.3Ta0.15} ) _O12 .

1-4-3. Production _of Solid Electrolyte _Pellets for _{Evaluation of Example 3} A mixed solution was prepared using the above raw material solutions so as to have a value of 0.2. Specifically, first, 8.160 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.500 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.200 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li that volatilizes during _main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 3 was produced using the calcined body. The composition formula showing the solid electrolyte pellet _{of Example 3} is _Li6.8La3 ( _{Zr1.5Sn0.3Ta0.2} ) _O12 .

1-4-4. _{Production of} Solid Electrolyte _Pellets for _Evaluation of _{Example 4} A mixed solution was prepared using the above raw material solutions so as to have a value of 0.2. Specifically, first, 8.160 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.700 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.100 g, 1 mol 0.200 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li that volatilizes during _main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 4 was produced using the calcined body. The _composition formula showing the solid electrolyte pellet _{of Example} 4 is _Li6.8La3 ( _{Zr1.7Sn0.1Ta0.2} ) _O12 .

1-4-5. _{Production of} Solid Electrolyte Pellets for _{Evaluation of Example 5} A mixed solution was prepared using the above raw material solutions so as to have a value of 0.2. Specifically, first, 8.160 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.600 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.200 g, 1 mol 0.200 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of /kg was weighed and stirred at room temperature for 30 minutes using a magnetic stirrer to obtain a mixed solution. In addition, considering the mass of Li volatilized during main firing, 8.160 g, which is 1.2 times the mass corresponding to Li _6.8 shown in the above composition formula when y = 0.2, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 5 was produced using the calcined body. The composition _formula showing the solid electrolyte pellet _{of Example} 2 is _Li6.8La3 ( _{Zr1.6Sn0.2Ta0.2} ) _O12 .

1-4-6. _{Preparation of Solid} Electrolyte _Pellets for Evaluation of _{Example 6} A mixed solution was prepared using the above raw material solutions so as to have a value of 0.2. Specifically, first, 8.160 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.400 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.400 g, 1 mol 0.200 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of /kg was weighed and stirred at room temperature for 30 minutes using a magnetic stirrer to obtain a mixed solution. In addition, considering the mass of Li volatilized during main firing, 8.160 g, which is 1.2 times the mass corresponding to Li _6.8 shown in the above composition formula when y = 0.2, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 6 was produced using the calcined body. The composition _formula showing the solid electrolyte pellet _{of Example} 6 is _Li6.8La3 ( _{Zr1.4Sn0.4Ta0.2} ) _O12 .

1-4-7. _{Production of} Solid _{Electrolyte Pellets} for _Evaluation of Example ₇ A mixed solution was prepared using the above raw material solutions so as to have a value of 0.3. Specifically, first, 8.040 g of a 2-butoxyethanol solution of 1 mol/kg lithium nitrate and 1 mol/kg lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stir bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.400 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.300 g of a 2-butoxyethanol solution of antimony tri-normal butoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li that volatilizes during _main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 7 was produced using the calcined body. _The composition formula showing the solid electrolyte pellet _of Example ₇ is _Li6.7La3 ( _{Zr1.4Sn0.3Sb0.3} ) _O12 .

1-4-8. _{Production of} Solid _{Electrolyte Pellets} for _Evaluation of Example ₈ A mixed solution was prepared using the above raw material solutions so as to have a value of 0.35. Specifically, first, 7.980 g of a 1 mol/kg concentration lithium nitrate 2-butoxyethanol solution and 1 mol/kg concentration lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.350 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.350 g of a 2-butoxyethanol solution of antimony tri-normal butoxide with a concentration/kg concentration was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li that _volatilizes during main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 8 was produced using the calcined body. _The composition formula showing _the solid electrolyte pellet _of Example 8 is _Li6.65La3 ( _{Zr1.35Sn0.3Sb0.35} ) _O12 .

1-4-9. _{Production of} Solid _{Electrolyte Pellets} for _Evaluation of Example ₉ A mixed solution was prepared using the above raw material solutions so as to have a value of 0.4. Specifically, first, 7.920 g of a 1 mol/kg concentration lithium nitrate 2-butoxyethanol solution and 1 mol/kg concentration lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.300 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.400 g of a 2-butoxyethanol solution of antimony tri-normal butoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li that volatilizes during _main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 9 was produced using the calcined body. _The composition formula showing the solid electrolyte pellet _{of Example} 9 is _Li6.6La3 ( _{Zr1.3Sn0.3Sb0.4} ) _O12 .

1-4-10. Production _of Solid Electrolyte _Pellets for _{Evaluation of Example 10} A mixed solution was prepared using the above raw material solutions so as to have a value of 0.25. Specifically, first, 8.100 g of a 1 mol/kg concentration lithium nitrate 2-butoxyethanol solution and 1 mol/kg concentration lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.450 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.250 g of a 2-butoxyethanol solution of niobium pentaethoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li volatilized during main firing, 8.100 g, which is 1.2 times the mass corresponding to Li _6.75 shown in the above composition formula when y = 0.25, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 10 was produced using the calcined body. The composition formula showing the solid electrolyte pellet _{of Example} 10 is _{Li6.75La3 ( Zr1.45Sn0.3Nb0.25} ) _O12 .

1-4-11. Production _of Solid Electrolyte _Pellets for _{Evaluation of Example 11} A mixed solution was prepared using the above raw material solutions so as to have a value of 0.3. Specifically, first, 8.040 g of a 1 mol/kg concentration lithium nitrate 2-butoxyethanol solution and 1 mol/kg concentration lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.400 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.300 g of a 2-butoxyethanol solution of niobium pentaethoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li that volatilizes during _main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 11 was produced using the calcined body. The composition _formula showing the solid electrolyte pellet _{of Example} 11 is _Li6.7La3 ( _{Zr1.4Sn0.3Nb0.3} ) _O12 .

1-4-12. _{Production of} Solid Electrolyte _Pellets for _Evaluation of _{Example 12} A mixed solution was prepared using the above raw material solutions so that the value was 0.25. Specifically, first, 8.100 g of a 1 mol/kg concentration lithium nitrate 2-butoxyethanol solution and 1 mol/kg concentration lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.650 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.100 g, 1 mol 0.250 g of a 2-butoxyethanol solution of niobium pentaethoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li volatilized during main firing, 8.100 g, which is 1.2 times the mass corresponding to Li _6.75 shown in the above composition formula when y = 0.25, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 12 was produced using the calcined body. The composition formula showing the solid electrolyte pellet _{of Example} 12 is _Li6.75La3 ( _{Zr1.65Sn0.1Nb0.25} ) _{O12 .}

1-4-13. Production _of Solid _{Electrolyte Pellets} for _Evaluation of _{Example 13} A mixed solution was prepared using the above raw material solutions so as to have a value of 0.3. Specifically, first, 8.040 g of a 2-butoxyethanol solution of 1 mol/kg lithium nitrate and 1 mol/kg lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stir bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.600 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.100 g, 1 mol 0.300 g of a 2-butoxyethanol solution of niobium pentaethoxide with a concentration of /kg was weighed and stirred at room temperature for 30 minutes using a magnetic stirrer to obtain a mixed solution. Considering the mass of Li that volatilizes during _main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 13 was produced using the calcined body. _The composition formula showing the solid electrolyte pellet _{of Example} 13 is _Li6.7La3 ( _{Zr1.6Sn0.1Nb0.3} ) _O12 .

1-4-14. _{Production of} Solid Electrolyte _Pellets for _{Evaluation of Example 14} A mixed solution was prepared using the raw material solutions so that the value was 0.15, the value of yb was 0.4, and the value of ya+yb=y was 0.55. Specifically, first, 7.740 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.150 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.150 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a /kg concentration and 0.400 g of a 2-butoxyethanol solution of antimony tri-normal butoxide with a concentration of 1 mol / kg were weighed, and using a magnetic stirrer, After stirring at room temperature for 30 minutes, a mixed solution was obtained. Considering the mass of Li that volatilizes during _main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 14 was produced using the calcined body. The composition formula showing the solid electrolyte pellet _{of Example 14} is _{Li6.45La3 ( Zr1.15Sn0.3Ta0.15Sb0.4} ) _O12 .

1-4-15. _{Production of} Solid Electrolyte _{Pellets for} Evaluation _{of Example 15} A mixed solution was prepared using the raw material solutions so that the value was 0.15, the value of yb was 0.15, and the value of ya+yb=y was 0.3. Specifically, first, 8.040 g of a 2-butoxyethanol solution of 1 mol/kg lithium nitrate and 1 mol/kg lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stir bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.400 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.150 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a /kg concentration and 0.150 g of a 2-butoxyethanol solution of niobium pentaethoxide with a concentration of 1 mol / kg were weighed, and using a magnetic stirrer, After stirring at room temperature for 30 minutes, a mixed solution was obtained. Considering the mass of Li that volatilizes during _main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 15 was produced using the calcined body. _The composition formula _{showing the} solid electrolyte pellet _of Example 15 is _Li6.7La3 ( _{Zr1.4Sn0.3Ta0.15Nb0.15} ) _O12 .

1-4-16. _{Preparation of} Solid Electrolyte _Pellets for _{Evaluation of Example 16} A mixed solution was prepared using the raw material solutions so that the value was 0.3, the value of yb was 0.15, and the value of ya+yb=y was 0.45. Specifically, first, 7.860 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.250 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.300 g of a 2-butoxyethanol solution of antimony tri-normal butoxide with a /kg concentration and 0.150 g of a 2-butoxyethanol solution of niobium pentaethoxide with a concentration of 1 mol/kg were weighed, and using a magnetic stirrer, After stirring at room temperature for 30 minutes, a mixed solution was obtained. Considering the mass of Li volatilized during main firing, 7.860 g, which is 1.2 times the mass corresponding to Li _6.55 shown in the above composition formula when y = 0.45, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 16 was produced using the calcined body. The composition formula showing _the solid electrolyte pellet _{of Example 16} is _Li6.55La3 ( _{Zr1.25Sn0.3Sb0.3Nb0.15} ) _O12 .

1-4-17. _{Production of} Solid Electrolyte _{Pellets for Evaluation of Example 17} A mixed solution is prepared using the raw material solution so that the value of ya is 0.2, the value of yb is 0.3, the value of yc is 0.2, and the value of ya+yb+yc=y is 0.7. bottom. Specifically, first, 7.560 g of a 2-butoxyethanol solution of 1 mol/kg lithium nitrate and 1 mol/kg lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.000 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.200 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of /kg, 0.300 g of a 2-butoxyethanol solution of antimony tri-normal butoxide with a concentration of 1 mol/kg, and 2 of niobium pentaethoxide with a concentration of 1 mol/kg. 0.200 g of the -butoxyethanol solution was weighed and stirred at room temperature for 30 minutes using a magnetic stirrer to obtain a mixed solution. In addition, considering the mass of Li volatilized during main firing, 7.560 g, which is 1.2 times the mass corresponding to Li _6.3 shown in the above composition formula when y = 0.7, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Example 17 was produced using the calcined body. The composition formula showing _the solid electrolyte _{pellet of} Example _{17 is Li6.3La3} ( _{Zr1.0Sn0.3Ta0.2Sb0.3Nb0.2} ) _O12 .

1-5. Comparative Examples of Solid Electrolyte The solid electrolyte manufacturing methods of Comparative Examples 1 to 12 use the raw material solutions of Li, La, Zr, and the metal element M in the solid electrolyte manufacturing methods of Examples 1 to 17. , in which the composition formula of the solid electrolyte is different from that in Examples 1 to 17.

1-5-1. _{Production of} Solid Electrolyte Pellets _{for Evaluation} in _{Comparative Example} 1 A mixed solution was prepared using the above raw material solutions so as to have a structure containing 0, that is, not containing the metal element M. Specifically, first, 8.750 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.700 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, They were weighed and stirred at room temperature for 30 minutes using a magnetic stirrer to obtain a mixed solution. In addition, considering the mass of Li volatilized during the main firing, 8.750 g, which is 1.25 times the mass corresponding to Li ₇ shown in the above composition formula when y = 0, is 1 mol / kg concentration of lithium nitrate in 2-butoxyethanol solution. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 1 was produced using the calcined body. The composition _formula showing the solid electrolyte pellet of Comparative Example ₁ is _Li7La3 ( _Zr1.7Sn0.3 ) _O12 .

1-5-2. _{Production of} Solid Electrolyte Pellets _{for Evaluation in} Comparative _Example 2 A mixed solution was prepared using the above raw material solutions so as to have a value of 0.3. Specifically, first, 8.040 g of a 2-butoxyethanol solution of 1 mol/kg lithium nitrate and 1 mol/kg lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stir bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.400 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.300 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li that volatilizes during _main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 2 was produced using the calcined body. _The composition formula showing the solid electrolyte pellet _{of Comparative} Example 2 is _Li6.7La3 ( _{Zr1.4Sn0.3Ta0.3} ) _O12 .

1-5-3. _{Production of} Solid Electrolyte Pellets for _Evaluation in _{Comparative Example 3} A mixed solution was prepared using the above raw material solutions so as to have a value of 0.4. Specifically, first, 7.920 g of a 1 mol/kg concentration lithium nitrate 2-butoxyethanol solution and 1 mol/kg concentration lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.300 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.400 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li that volatilizes during _main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 3 was produced using the calcined body. The composition formula showing the solid electrolyte pellet _of Comparative Example ₃ is _Li6.6La3 ( _{Zr1.3Sn0.3Ta0.4} ) _{O12 .}

1-5-4. Production of Solid Electrolyte Pellets for Evaluation in Comparative Example 4 In Comparative Example 4, the value of x in _the composition formula Li7 _{-yLa3 ( Zr2- xySnxTay} ) _O12 is 0, that is, the composition does not contain Sn. and a mixed solution was prepared using the raw material solutions so that the value of y was 0.2. Specifically, first, 8.500 g of a 2-butoxyethanol solution of 1 mol/kg lithium nitrate and 1 mol/kg lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of a 2-butoxyethanol solution of , 1.800 g of a butanol solution of zirconium tetra-normal butoxide with a concentration of 1 mol/kg, and 0.200 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of 1 mol/kg. and stirred at room temperature for 30 minutes using a magnetic stirrer to obtain a mixed solution. In addition, considering the mass of Li volatilized during main firing, 8.500 g, which is 1.25 times the mass corresponding to Li _6.8 shown in the above composition formula when y = 0.2, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 4 was produced using the calcined body. The composition formula showing the solid electrolyte pellet of Comparative Example 4 is Li _6.8 La ₃ (Zr _1.8 Ta _0.2 )O ₁₂ .

1-5-5. _{Production of} Solid Electrolyte Pellets for _{Evaluation in Comparative Example} 5 A mixed solution was prepared using the above raw material solutions so as to have a value of 0.2. Specifically, first, 8.160 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.300 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.500 g, 1 mol 0.200 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of /kg was weighed and stirred at room temperature for 30 minutes using a magnetic stirrer to obtain a mixed solution. In addition, considering the mass of Li volatilized during main firing, 8.160 g, which is 1.2 times the mass corresponding to Li _6.8 shown in the above composition formula when y = 0.2, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 5 was produced using the calcined body. The _composition formula showing the solid electrolyte pellet _of Comparative _Example 5 is _Li6.8La3 ( _{Zr1.3Sn0.5Ta0.2} ) _O12 .

1-5-6. _{Production of} Solid Electrolyte Pellets for _{Evaluation in Comparative Example} 6 A mixed solution was prepared using the above raw material solutions so as to have a value of 0.2. Specifically, first, 8.160 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.100 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.700 g, 1 mol 0.200 g of a 2-butoxyethanol solution of tantalum penta-normal butoxide with a concentration of /kg was weighed and stirred at room temperature for 30 minutes using a magnetic stirrer to obtain a mixed solution. In addition, considering the mass of Li volatilized during main firing, 8.160 g, which is 1.2 times the mass corresponding to Li _6.8 shown in the above composition formula when y = 0.2, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 6 was produced using the calcined body. The composition formula showing the solid electrolyte pellet of Comparative Example 6 is Li _6.8 La ₃ (Zr _1.1 Sn _0.7 Ta _0.2 )O ₁₂ .

1-5-7. _{Production of} Solid Electrolyte Pellets for _{Evaluation in Comparative Example} 7 A mixed solution was prepared using the above raw material solutions so as to have a value of 0.05. Specifically, first, 8.340 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.650 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.050 g of a 2-butoxyethanol solution of antimony tri-normal butoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. In addition, considering the mass of Li volatilized during main firing, 8.340 g, which is 1.2 times the mass corresponding to Li _6.95 shown in the above composition formula when y = 0.05, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 7 was produced using the calcined body. The composition formula showing the solid electrolyte pellet _of Comparative _Example 7 is _{Li6.95La3 ( Zr1.65Sn0.3Sb0.05} ) _O12 .

1-5-8. _{Production of} Solid Electrolyte Pellets for _{Evaluation in Comparative Example} 8 A mixed solution was prepared using the above raw material solutions so as to have a value of 0.6. Specifically, first, 7.680 g of a 2-butoxyethanol solution of 1 mol/kg lithium nitrate and 1 mol/kg lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.100 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.600 g of a 2-butoxyethanol solution of antimony tri-normal butoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li volatilized during main firing, 7.680 g, which is 1.2 times the mass corresponding to Li _6.4 shown in the above composition formula when y = 0.6, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 8 was produced using the calcined body. _The composition formula showing the solid electrolyte pellet _of Comparative _Example 8 is _Li6.4La3 ( _{Zr1.1Sn0.3Sb0.6} ) _O12 .

1-5-9. _{Production of} Solid Electrolyte Pellets for _{Evaluation in Comparative Example} 9 A mixed solution was prepared using the above raw material solutions so as to have a value of 0.2. Specifically, first, 8.160 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.500 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.200 g of a 2-butoxyethanol solution of antimony tri-normal butoxide having a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. In addition, considering the mass of Li volatilized during main firing, 8.160 g, which is 1.2 times the mass corresponding to Li _6.8 shown in the above composition formula when y = 0.2, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 9 was produced using the calcined body. The composition _formula showing the solid electrolyte pellet _of Comparative Example ₉ is _Li6.8La3 ( _{Zr1.5Sn0.3Sb0.2} ) _O12 .

1-5-10. _{Production of} Solid Electrolyte _Pellets for _Evaluation in _{Comparative Example} 10 A mixed solution was prepared using the above raw material solutions so as to have a value of 0.35. Specifically, first, 7.980 g of a 1 mol/kg concentration lithium nitrate 2-butoxyethanol solution and 1 mol/kg concentration lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.350 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.300 g, 1 mol 0.350 g of a 2-butoxyethanol solution of niobium pentaethoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li that _volatilizes during main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 10 was produced using the calcined body. The composition formula showing the solid electrolyte pellet _{of Comparative} Example 10 is _{Li6.65La3 ( Zr1.35Sn0.3Nb0.35} ) _O12 .

1-5-11. _{Production of} Solid Electrolyte Pellets for _Evaluation in _{Comparative Example 11} A mixed solution was prepared using the above raw material solutions so as to have a value of 0.1. Specifically, first, 8.280 g of a 2-butoxyethanol solution of lithium nitrate with a concentration of 1 mol/kg and lanthanum nitrate hexahydrate with a concentration of 1 mol/kg were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.800 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.100 g, 1 mol 0.100 g of a 2-butoxyethanol solution of niobium pentaethoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li volatilized during main firing, 8.280 g, which is 1.2 times the mass corresponding to Li _6.9 shown in the above composition formula when y = 0.1, is 1 mol / It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 11 was produced using the calcined body. The composition formula showing the solid electrolyte pellet _{of Comparative} Example ₁₁ is _Li6.9La3 ( _{Zr1.8Sn0.1Nb0.1} ) _O12 .

1-5-12. Production _{of Solid} Electrolyte Pellets for _Evaluation in _{Comparative Example 12} A mixed solution was prepared using the above raw material solutions so as to have a value of 0.35. Specifically, first, 7.980 g of a 1 mol/kg concentration lithium nitrate 2-butoxyethanol solution and 1 mol/kg concentration lanthanum nitrate hexahydrate were added to a Pyrex reagent bottle containing a magnetic stirrer bar. 3.000 g of 2-butoxyethanol solution of 1 mol/kg concentration of zirconium tetra-normal butoxide in butanol solution of 1.550 g, 1 mol/kg concentration of tin tetraisopropoxide in 2-butoxyethanol solution of 0.100 g, 1 mol 0.350 g of a 2-butoxyethanol solution of niobium pentaethoxide with a concentration of /kg was weighed and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a mixed solution. Considering the mass of Li that _volatilizes during main firing, 1 mol/ It is the mass of a 2-butoxyethanol solution of lithium nitrate with a concentration of kg. Thereafter, through the same steps as in Example 1, a calcined body was formed from the mixed solution, and a solid electrolyte pellet for evaluation in Comparative Example 12 was produced using the calcined body. The composition formula _showing the solid electrolyte pellet _of Comparative _Example 12 is _Li6.65La3 ( _{Zr1.55Sn0.1Nb0.35} ) _O12 .

1-6. Evaluation of Solid Electrolyte Pellets of Examples 1 to 17 and Comparative Examples 1 to 12 For each of the solid electrolyte pellets of Examples 1 to 17 and Comparative Examples 1 to 12, a metal having a diameter of Φ of 5 mm was placed on both sides of the solid electrolyte pellet. A Li foil is pressed to form an activated electrode. Then, an electrochemical impedance (EIS) measurement was performed using an AC impedance analyzer Solatron 1260 (manufactured by Solatron Anailtical) to obtain the lithium ion conductivity. EIS measurements were performed in the frequency range from 10 ⁷ Hz to 10 ⁻¹ Hz at an alternating current (AC) amplitude of 10 mV. The lithium ion conductivity obtained by EIS measurements represents the total lithium ion conductivity, including the bulk lithium ion conductivity and the grain boundary lithium ion conductivity in the solid electrolyte pellet. Table 1 shows the lithium ion conductivity of each of the solid electrolyte pellets of Examples 1-17. Table 2 shows the lithium ion conductivity of each of the solid electrolyte pellets of Comparative Examples 1-12.

As shown in Table 1 above, in the solid electrolytes of Examples 1 to 13, the range of the stoichiometric composition ratio x of Sn substituting a part of the Zr site in the composition formula is 0.1 ≤ x ≤ 0 .4. Further, when Ta is selected as the element M, the range of the stoichiometric composition ratio y of Ta is 0.1 ≤ y ≤ 0.2, and when Sb is selected, the stoichiometric composition ratio of Sb The range of y is 0.3≤y≤0.4, and the range of the stoichiometric composition ratio y of Nb when Nb is selected is 0.25≤y≤0.3. In such a range of the stoichiometric composition ratio y of the element M, one or more of Ta, Sb, and Nb are selected, and a part of the Zr site is substituted with the element M along with Sn. In either case, a solid electrolyte exhibiting a high lithium ion conductivity of 1.0×10 ⁻⁴ (S (Siemens)/cm) or more can be realized.
Further, in the solid electrolytes of Examples 14 to 17, the stoichiometric composition ratio x of Sn substituting a part of Zr sites in the composition formula was 0.3. In addition, as the element M, two or more metal elements are selected from Ta, Sb, and Nb. The range of the stoichiometric composition ratio yb is 0.3≦yb≦0.4, and the range of the stoichiometric composition ratio yc of Nb is 0.15≦yc≦0.2. The solid electrolytes of Examples 14 to 17 had higher lithium ion conductivity than Examples 1 to 13 in which one metal element was selected by selecting two metal elements from Ta, Sb, and Nb. Realized.

As shown in Table 2 above, lithium solid electrolytes of Comparative Example 1 having a configuration in which a portion of the Zr site was replaced only with Sn and Comparative Example 4 having a configuration in which a portion of the Zr site was replaced only with Ta The ionic conductivity decreased from the 1.0×10 ⁻⁶ (S/cm) level to the 1.0×10 ⁻⁵ (S/cm) level, lower than in Examples 1-17.

In Comparative Example 2, in which the Sn stoichiometric composition ratio x was 0.3 and the Ta stoichiometric composition y value was 0.3, lithium ion conduction The rate was 6.4×10 ⁻⁵ (S/cm), which was higher than Comparative Example 1, but lower than that of Examples 1 to 6 by one order of magnitude. Furthermore, in Comparative Example 3 in which the stoichiometric composition ratio y of Ta was increased to 0.4 compared to Comparative Example 2, the lithium ion conductivity could not be obtained by EIS measurement.

The value of the Sn stoichiometric composition ratio x, which replaces a part of the Zr site, is set to 0.5, which is larger than 0.3, and the value of the Ta stoichiometric composition ratio y is set to 0.2. In Comparative Example 5, the lithium ion conductivity was 6.6×10 ^-5 (S/cm), which was the same level as in Comparative Example 2, and was one digit lower than in Examples 1 to 6. . Furthermore, compared to Comparative Example 5, Comparative Example 6, in which the Sn stoichiometric composition ratio x was increased to 0.7, had a lithium ion conductivity of 1.6×10 ⁻⁵ (S/cm). decreased slightly.

In Comparative Example 7, in which the Sn stoichiometric composition ratio x was set to 0.3 and the Sb stoichiometric composition ratio y was set to 0.05, lithium ion conduction The rate was 5.6×10 ^-5 (S/cm), which was one order of magnitude lower than that of Examples 7-9. In addition, compared to Comparative Example 7, in Comparative Example 9 in which the value of the stoichiometric composition ratio y of Sb was increased to 0.2, and in Comparative Example 8 in which the value of the stoichiometric composition ratio y was increased to 0.6, the lithium ion conductivity was almost It was at the same level, which was one order of magnitude lower than in Examples 7-9.

In Comparative Example 10, in which the Sn stoichiometric composition ratio x was set to 0.3 and the Nb stoichiometric composition ratio y was set to 0.35, lithium ion conduction The rate was 5.5×10 ⁻⁵ (S/cm), which was one order of magnitude lower than that of Examples 10-13. Further, compared to Comparative Example 10, the value of the stoichiometric composition ratio x of Sn was set to 0.1, and the value of the stoichiometric composition ratio y of Nb was reduced to 0.1. Lithium ion conduction of Comparative Example 11 Comparative Example 12, in which the value of the stoichiometric composition ratio y of Nb was increased to 0.35 with respect to Comparative Example 11, was 6.5×10 ⁻⁵ (S/cm). The conductivity was 6.0×10 ⁻⁵ (S/cm), which was one order of magnitude lower than that of Examples 10-13.

According to the lithium ion conductivity of each solid electrolyte of Examples 1 to 17 and Comparative Examples 1 to 12 above, in the garnet-type solid electrolyte represented by the following composition formula (1), part of the Zr site was replaced The stoichiometric composition ratio x of Sn is preferably in the range of 0.1≦x<0.5.
Moreover, when the element M is Ta, the stoichiometric composition ratio y of Ta in the composition formula (1) is preferably 0.1≦y≦0.2.
Moreover, when the element M is Sb, the stoichiometric composition ratio y of Sb in the composition formula (1) is preferably 0.3≦y≦0.5.
Moreover, when the element M is Nb, the stoichiometric composition ratio y of Nb in the composition formula (1) is preferably 0.15≦y≦0.3.
Further, when two or more elements M are selected from among Ta, Sb, and Nb, the stoichiometric composition ratio y of the element M in the composition formula (1) is 0.3 ≤ y ≤ 0.7. preferable.
Li7 _{-yLa3 (} Zr2 _{-xySnxMy ) O12} ( ₁ )

According to the said 1st Embodiment, the following effects are acquired.
(1) The garnet-type solid electrolyte of the present embodiment is represented by the composition formula Li7 _{-yLa3 ( Zr2- xySnxMy} ) _O12 , where M is selected from Ta, _Sb , and Nb. One or more selected metal elements satisfying 0.1≦x<0.5 and 0.1≦y≦0.7. According to this, since a part of the Zr site in the crystal structure is replaced with Sn and one or more metal elements M selected from Ta, Sb, and Nb, it is possible to sinter the oxide. A garnet-type solid electrolyte having a high lithium ion conductivity can be provided while the temperature of the main sintering can be lowered. In the above composition formula, the stoichiometric composition ratio x of Sn is preferably in the range of 0.1≦x<0.5. Further, when Ta is selected as the metal element M, the stoichiometric composition ratio y of Ta is preferably in the range of 0.1 ≤ y ≤ 0.2, and when Sb is selected, the stoichiometric composition ratio of Sb y is preferably in the range of 0.3≦y≦0.5, and when Nb is selected, the stoichiometric composition ratio y of Nb is preferably in the range of 0.15≦y≦0.3. Furthermore, from the viewpoint of realizing a higher lithium ion conductivity, it is preferable that two or more of Ta, Sb, and Nb be selected as the metal element M.

(2) The method for producing a garnet-type solid electrolyte according to the present embodiment is represented by the composition formula Li7 _{-yLa3 ( Zr2- xySnxMy ) O12} , where M is Ta, Sb , Nb, satisfying 0.1 ≤ x < 0.5 and 0.1 ≤ y ≤ 0.7, with respect to the stoichiometric composition of the above composition formula , a lithium raw material solution in which a lithium compound is dissolved at a concentration of 1.05 to 1.2 times, a lanthanum raw material solution in which a lanthanum compound is dissolved at an equal concentration, and a zirconium compound dissolved at an equal concentration. a step of mixing a raw material solution, a tin raw material solution in which a tin compound is dissolved at an equal concentration, and a metal raw material solution in which a metal compound containing a metal element M is dissolved at an equal concentration to obtain a mixed solution; a step of subjecting the mixed solution to a first heat treatment and drying to obtain a mixture; a step of subjecting the mixture to a second heat treatment to obtain an oxide; and a step of subjecting the oxide to a third heat treatment and sintering and a step of causing.
According to this method, the temperature of the third heat treatment for sintering the oxide can be lowered to 950° C. or lower, and a garnet-type solid electrolyte having high lithium ion conductivity can be produced.

(3) A lithium ion battery 100 as a secondary battery of the present embodiment has a positive electrode mixture 10, an electrolyte layer 20, and a negative electrode 30, which are arranged between a pair of current collectors 41 and 42. The negative electrode 30 is made of metal Li. The positive electrode mixture 10 includes a particulate positive electrode active material 11 made of a lithium composite metal oxide and a garnet-type solid electrolyte 12 of the present embodiment filled between the particulate positive electrode active materials 11. It is Therefore, the area of the interface between the positive electrode active material 11 and the solid electrolyte 12 is large, and the solid electrolyte 12 has a high lithium ion conductivity. It is possible to provide the lithium ion battery 100 having excellent charging/discharging characteristics because the lithium ions are conducted and the battery reaction proceeds.

2. Second embodiment 2-1. Electronic Device Next, the electronic device of the present embodiment will be described by taking a wearable device as an example. FIG. 7 is a perspective view showing the configuration of a wearable device as an electronic device according to the second embodiment.

As shown in FIG. 7, a wearable device 500 as an electronic device of the present embodiment is an information device that is worn on a human body, for example, a wrist WR, like a wristwatch, and is capable of obtaining information related to the human body. , a sensor 502 , a display unit 503 , a processing unit 504 and a battery 505 .

The band 501 has a belt-like shape using a flexible resin such as rubber so as to be in close contact with the wrist WR when worn, and has a connecting portion at the end of the band whose connecting position can be adjusted. .

The sensor 502 is, for example, an optical sensor, and is arranged inside the band 501 so as to touch the wrist WR when worn.

The display unit 503 is, for example, a light-receiving liquid crystal display device, and is arranged on the outer surface side of the band 501 opposite to the inner surface on which the sensor 502 is attached so that the wearer can read the information displayed on the display unit 503. It is

The processing unit 504 is, for example, an integrated circuit (IC), built in the band 501 and electrically connected to the sensor 502 and the display unit 503 . Based on the output from the sensor 502, the processing unit 504 performs arithmetic processing for measuring the pulse, blood sugar level, and the like. In addition, it controls the display unit 503 to display the measurement results and the like.

A battery 505 is incorporated in the band 501 as a power supply source that supplies power to the sensor 502, the display unit 503, the processing unit 504, and the like. As the battery 505, the lithium ion battery 100 of the first embodiment is used.

According to the wearable device 500 of the present embodiment, the sensor 502 electrically detects the wearer's pulse and blood sugar level information from the wrist WR. You can display your pulse, blood sugar level, etc. The display unit 503 can display not only the measurement result but also information indicating the state of the human body predicted from the measurement result, the time, and the like.

In addition, since the lithium-ion battery 100 that is compact and has excellent charge-discharge characteristics is used as the battery 505, it is possible to provide the wearable device 500 that is lightweight and thin and can withstand repeated use over a long period of time. can.

Also, in the present embodiment, the wristwatch-type wearable device 500 is exemplified, but the wearable device 500 may be worn on the ankle, head, ear, waist, or the like, for example.

The electronic device to which the lithium-ion battery 100 of this embodiment is applied as a power supply source is not limited to the wearable device 500 . Examples include head-mounted displays, head-up displays, mobile phones, personal digital assistants, laptop computers, digital cameras, video cameras, music players, wireless headphones, and game machines. Moreover, it is applicable not only to such devices for general consumers but also to devices for industrial use.

Further, the electronic device equipped with the secondary battery using the solid electrolyte of the present embodiment may be a moving object such as an automobile or a ship. For example, as a storage battery for electric vehicles (EV), plug-in hybrid vehicles (PHEV), hybrid vehicles (HEV), fuel cell vehicles (FCV), etc., a lithium ion battery as a secondary battery using the solid electrolyte of the present embodiment can be preferably employed. In that case, since the storage battery for the moving body is a power source for driving the motor, it is required to have a large electric capacity and be capable of being charged and discharged quickly. It is preferable to increase the volume fraction of the solid electrolyte 12 by limiting the volume fraction to 40%.

The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made to the above-described embodiments. Modifications are described below.

(Modification 1) The secondary battery having the garnet-type solid electrolyte of the present embodiment is not limited to the all-solid-state lithium ion battery 100 shown in the above embodiment. For example, a secondary battery may be constructed by providing a porous separator between the positive electrode mixture 10 and the negative electrode 30 and impregnating the separator with an electrolytic solution.

The contents derived from the embodiment are described below.

The garnet-type solid electrolyte of the present application is represented by the composition formula Li7 _{-yLa3 ( Zr2 - xySnxMy} ) _O12 , where M is one or more selected from Ta, Sb, and Nb. and is characterized by satisfying 0.1≦x<0.5 and 0.1≦y≦0.7.

According to the configuration of the present application, part of the zirconium (Zr) sites in the crystal structure is replaced with tin (Sn) and one or more metal elements M selected from Ta, Sb, and Nb. Therefore, it is possible to lower the temperature in sintering the oxide, and to provide a garnet-type solid electrolyte having high lithium ion conductivity.

In the garnet-type solid electrolyte described above, M is one metal element selected from Ta, Sb, and Nb, and when M is Ta, 0.1 ≤ y ≤ 0.2 is satisfied. , when M is Sb, 0.3≦y≦0.5, and when M is Nb, 0.15≦y≦0.3.
According to this configuration, high lithium ion conductivity can be achieved in the garnet-type solid electrolyte.

In the garnet-type solid electrolyte described above, M is preferably two or more metal elements selected from Ta, Sb, and Nb.
According to this configuration, in the garnet-type solid electrolyte, part of the Zr sites are replaced with two or more metal elements selected from Ta, Sb, and Nb, thereby achieving higher lithium ion conductivity. can be realized.

A method for producing a garnet-type solid electrolyte _of the present application is a method for producing a garnet-type solid electrolyte represented by the following composition formula (1), wherein Li7 _{-yLa3 ( Zr2-xySnxMy )} O ₁₂ (1) M is one or more metal elements selected from Ta, Sb, and Nb, and satisfies 0.1≦x<0.5 and 0.1≦y≦0.7; and a lithium raw material solution in which a lithium compound containing 1.05 times or more and 1.2 times or less of lithium with respect to the stoichiometric composition of the composition formula (1) is dissolved, and the stoichiometric composition of the composition formula (1) A lanthanum raw material solution in which a lanthanum compound containing lanthanum in an amount equal to the composition is dissolved, and a zirconium raw material solution in which a zirconium compound containing zirconium in an amount equal to the stoichiometric composition of the composition formula (1) is dissolved; A tin raw material solution in which a tin compound containing tin is dissolved in an amount equivalent to the stoichiometric composition of the composition formula (1), and a metal element M equivalent to the stoichiometric composition of the composition formula (1). A metal raw material solution in which a metal compound containing the and a step of subjecting the oxide to a third heat treatment to sinter the oxide.

According to the method of the present application, the temperature of the third heat treatment for sintering the oxide can be lowered to 950° C. or lower, and a garnet-type solid electrolyte having high lithium ion conductivity can be produced.

In the method for producing a garnet-type solid electrolyte described above, the heating temperature of the first heat treatment is 50° C. or higher and 250° C. or lower, and the heating temperature of the second heat treatment is 400° C. or higher and 550° C. or lower. The heating temperature of the third heat treatment is preferably 800° C. or higher and 950° C. or lower.
According to this method, the first heat treatment removes the solvent component and dries, the second heat treatment produces an oxide at a temperature at which by-products are unlikely to occur, and the third heat treatment evaporates lithium. can be suppressed to sinter the oxide to produce a garnet-type solid electrolyte with high lithium ion conductivity.

The secondary battery of the present application includes a positive electrode mixture containing the garnet-type solid electrolyte described above and a positive electrode active material containing lithium, an electrode provided on one surface of the positive electrode mixture, and a positive electrode mixture. and a current collector provided on the other surface.

According to the configuration of the present application, since the garnet-type solid electrolyte has excellent lithium ion conductivity, lithium ions are smoothly conducted between the positive electrode active material and the solid electrolyte in the positive electrode mixture. In other words, it is possible to provide a secondary battery with improved electrical resistance in the positive electrode mixture and excellent charge-discharge characteristics.

In the secondary battery described above, the positive electrode active material is preferably a lithium composite metal oxide.
According to this configuration, since the lithium composite metal oxide is used as the positive electrode active material, high lithium ion conductivity can be achieved, and a thermally stable secondary battery can be provided.

In the secondary battery described above, the electrode is preferably metallic lithium.
With this configuration, a high battery capacity can be achieved even when the secondary battery is miniaturized.

An electronic device according to the present application includes the secondary battery described above.
According to the configuration of the present application, since the constituent elements are made of solid materials and equipped with a secondary battery having excellent charge/discharge characteristics as a power supply, it is possible to provide an electronic device with high reliability and quality that can withstand long-term use. be able to.

DESCRIPTION OF SYMBOLS 10... Positive electrode compound material 11... Positive electrode active material 12... Solid electrolyte 20... Electrolyte layer 30... Negative electrode as an electrode 41, 42... Current collector 100... Lithium ion battery as a secondary battery 500... Wearable devices as electronic devices.

Claims (8)

Represented _by the composition formula Li7 _{-yLa3 (} Zr2 _{- xySnxMy} ) _O12 ,
A garnet-type solid electrolyte that satisfies 0.1≦x<0.5 and 0.1≦y≦0.7,
The M is one metal element selected from Ta, Sb, and Nb,
When the M is Ta, satisfying 0.1 ≤ y ≤ 0.2,
When the M is Sb, 0.3 ≤ y ≤ 0.5 is satisfied,
when the M is Nb, satisfying 0.15 ≤ y ≤ 0.3;
Garnet type solid electrolyte. 2. The garnet-type solid electrolyte according to claim 1, wherein said M is two or more metal elements selected from Ta, Sb, and Nb. A method for producing a garnet-type solid electrolyte represented by the following compositional formula (1),
Li7 _{-yLa3 (} Zr2 _{-xySnxMy ) O12} ( ₁ )
The M is one or more metal elements selected from Ta, Sb, and Nb,
satisfying 0.1 ≤ x < 0.5, 0.1 ≤ y ≤ 0.7,
a lithium raw material solution in which a lithium compound containing 1.05 times or more and 1.2 times or less of lithium with respect to the stoichiometric composition of the composition formula (1) is dissolved;
A lanthanum raw material solution in which a lanthanum compound containing an equal amount of lanthanum with respect to the stoichiometric composition of the composition formula (1) is dissolved;
A zirconium raw material solution in which a zirconium compound containing zirconium equivalent to the stoichiometric composition of the composition formula (1) is dissolved;
A tin raw material solution in which a tin compound containing tin in an amount equal to the stoichiometric composition of the composition formula (1) is dissolved;
a step of obtaining a mixed solution by mixing a metal raw material solution in which a metal compound containing a metal element M in an amount equal to the stoichiometric composition of the composition formula (1) is dissolved;
a step of subjecting the mixed solution to a first heat treatment and drying to obtain a mixture;
subjecting the mixture to a second heat treatment to obtain an oxide;
A method for producing a garnet-type solid electrolyte, comprising the step of subjecting the oxide to a third heat treatment and sintering it ,
The M is one metal element selected from Ta, Sb, and Nb,
When the M is Ta, satisfying 0.1 ≤ y ≤ 0.2,
When the M is Sb, 0.3 ≤ y ≤ 0.5 is satisfied,
when the M is Nb, satisfying 0.15 ≤ y ≤ 0.3;
A method for producing a garnet-type solid electrolyte. The heating temperature of the first heat treatment is 50° C. or higher and 250° C. or lower,
The heating temperature of the second heat treatment is 400° C. or higher and 550° C. or lower,
4. The method for producing a garnet-type solid electrolyte according to claim 3 , wherein the heating temperature of said third heat treatment is 800[deg.] C. or higher and 950[deg.] C. or lower. A positive electrode mixture comprising the garnet-type solid electrolyte according to claim 1 or claim 2 and a positive electrode active material containing lithium;
an electrode provided on one surface of the positive electrode mixture;
and a current collector provided on the other surface of the positive electrode mixture. 6. The secondary battery according to claim 5 , wherein said positive electrode active material is a lithium composite metal oxide. 7. The secondary battery according to claim 5 , wherein said electrode is metallic lithium. An electronic device comprising the secondary battery according to claim 5 .

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