JP2011222415A - Solid electrolyte material, lithium battery, and method for manufacturing solid electrolyte material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Li-La-Ti-O based solid electrolyte material having low electric resistance.SOLUTION: The solid electrolyte material is a crystalline material, has a thin-film shape and is represented by expression Li(LaM1)(TiM2)Oin which x satisfies 0<x<2/3, a satisfies 0≤a≤0.5, b satisfies 0≤b≤0.5, M1 is at least one selected from the group consisting of Sr, Na, Nd, Pr, Sm, Gd, Dy, Y, Eu, Tb and Ba, and M2 is at least one selected from the group consisting of Mg, W, Mn, Al, Ge, Ru, Nb, Ta, Co, Zr, Hf, Fe, Cr and Ga.

Description

  The present invention relates to a Li-La-Ti-O-based solid electrolyte material having a low resistance value.

  With the rapid spread of information-related equipment and communication equipment such as personal computers, video cameras, and mobile phones in recent years, development of batteries that are used as power sources has been regarded as important. Also in the automobile industry and the like, development of high-power and high-capacity batteries for electric vehicles or hybrid vehicles is being promoted. Currently, lithium batteries are attracting attention among various batteries from the viewpoint of high energy density.

  Since lithium batteries currently on the market use an electrolyte containing a flammable organic solvent, it is possible to install safety devices that suppress the temperature rise during short circuits and to improve the structure and materials to prevent short circuits. Necessary. In contrast, a lithium battery in which the electrolyte is changed to a solid electrolyte layer to make the battery completely solid does not use a flammable organic solvent in the battery. It is considered excellent.

Li-La-Ti-O-based solid electrolyte material (LLT) is known as a solid electrolyte material used for all solid lithium batteries. For example, Non-Patent Document 1 discloses a Li _0.5 La _0.5 TiO ₃ amorphous thin film. The composition of this thin film corresponds to x = 0.17 in the general formula Li _3x La _{2 / 3-x} TiO ₃ . Further, in Patent Document 1, a solid electrolyte film having lithium ion _{conductivity, La X Li Y Ti Z O} 3 (0.4 ≦ X ≦ 0.6,0.4 ≦ Y ≦ 0.6, A solid electrolyte membrane having a composition of 0.8 ≦ Z ≦ 1.2 and Y <X) and having an amorphous structure is disclosed. This composition range is completely different from the composition range of Li _3x La _{2 / 3-x} TiO ₃ .

Moreover, in patent document 2, it is a solid electrolyte layer comprised by the solid electrolyte which consists of complex oxide containing Li, La, and Ti, Comprising: It has an amorphous layer, a crystalline layer, and a lattice defect layer A solid electrolyte layer is disclosed. Further, Patent Document 2 describes that the composition of the solid electrolyte material is preferably La _{2 / 3-x} Li _3x TiO ₃ (0.03 ≦ x ≦ 0.167). The solid electrolyte material corresponds to a so-called bulk body synthesized by performing a planetary ball mill and firing, and is not a thin film.

Patent Document 3 discloses an electrolyte particle obtained by mechanically mixing a raw material crystal particle of an electrolyte having lithium ion conductivity and a lithium salt to cause distortion in the crystal structure of the raw material crystal particle. ing. Furthermore, Patent Document 3 describes that the composition of the raw material crystal particles is preferably La _{2 / 3-x} Li _3x TiO ₃ (x = 0.05 to 1.5).

JP 2009-238704 A JP 2008-059843 A JP 2009-215130 A

Jun-Ku Ahn et al., “Characteristics of perovskite (Li0.5La0.5) TiO3 solid electrolyte thin films grown by pulsed laser deposition for rechargeable lithium micorobattery”, Electrochimica Acta 50 (2004) 371-374

  From the viewpoint of increasing the output of a battery, a solid electrolyte material having a low resistance value is required. This invention is made | formed in view of the said situation, and makes it a main objective to provide a Li-La-Ti-O type solid electrolyte material with low resistance value.

In order to solve the above problems, in the present invention, the general formula Li _3x (La _{(2 / 3-x) -a} M1 _a ) (Ti _1-b M2 _b ) O ₃ is represented, and x is 0 < x <2/3 is satisfied, a satisfies 0 ≦ a ≦ 0.5, b satisfies 0 ≦ b ≦ 0.5, and M1 includes Sr, Na, Nd, Pr, Sm, Gd, It is at least one selected from the group consisting of Dy, Y, Eu, Tb, Ba, and M2 is Mg, W, Mn, Al, Ge, Ru, Nb, Ta, Co, Zr, Hf, Fe, Cr A solid electrolyte material characterized by being at least one selected from the group consisting of Ga, crystalline, and in the form of a thin film.

  According to the present invention, the Li—La—Ti—O-based solid electrolyte material having a low resistance value can be obtained because it has the above general formula, is crystalline, and is thin.

  In the said invention, it is preferable that said x satisfy | fills 0.07 <x <0.17. This is because a solid electrolyte material having a low resistance value can be obtained as described in the examples described later.

In the said invention, it is preferable that said x satisfy | fills 0.10 <= x <= 0.15. The resistance value of the solid electrolyte material of the present invention is based on the resistance value of the solid electrolyte material (Li _0.5 La _0.5 TiO ₃ , x = 0.17, amorphous) described in Non-Patent Document 1 described above. This is because it can be lowered.

  In the said invention, it is preferable that said a and said b are 0.

  In the present invention, a positive electrode active material layer containing a positive electrode active material, a negative electrode active material layer containing a negative electrode active material, and a solid electrolyte formed between the positive electrode active material layer and the negative electrode active material layer A lithium battery containing a layer, wherein the solid electrolyte layer contains the solid electrolyte material described above.

  According to this invention, it can be set as a high output lithium battery by using the solid electrolyte material mentioned above.

In the present invention, Li, La, Ti, M1 (M1 is at least one selected from the group consisting of Sr, Na, Nd, Pr, Sm, Gd, Dy, Y, Eu, Tb, and Ba. ), And M2 (M2 is at least one selected from the group consisting of Mg, W, Mn, Al, Ge, Ru, Nb, Ta, Co, Zr, Hf, Fe, Cr, and Ga). A raw material preparation step of preparing a raw material to be prepared, a thin film formation step of forming a LiLaTiO thin film on a substrate by a reactive vapor deposition method using oxygen using the raw material, and heating the LiLaTiO thin film It is represented by the formula Li _3x (La _{(2 / 3-x) -a} M1 _a ) (Ti _1-b M2 _b ) O _3, where x satisfies 0 <x <2/3, and a is 0 ≦ a ≦ 0.5, b is 0 Met b ≦ 0.5, crystalline, to provide a method of manufacturing a solid electrolyte material and having a heating process of forming a solid electrolyte material is a thin film shape, a.

  According to the present invention, a dense LiLaTiO thin film can be formed by using a reactive vapor deposition method, and a solid electrolyte material with high crystallinity can be formed by performing heat treatment. As a result, a Li—La—Ti—O-based solid electrolyte material having a low resistance value can be obtained.

  In the said invention, it is preferable that said x satisfy | fills 0.07 <x <0.17. This is because a solid electrolyte material having a low resistance value can be obtained as described in the examples described later.

In the said invention, it is preferable that said x satisfy | fills 0.10 <= x <= 0.15. The resistance value of the solid electrolyte material of the present invention is based on the resistance value of the solid electrolyte material (Li _0.5 La _0.5 TiO ₃ , x = 0.17, amorphous) described in Non-Patent Document 1 described above. This is because it can be lowered.

  In the said invention, it is preferable to form the said LiLaTiO thin film by the reactive vapor deposition method using oxygen plasma in the said thin film formation process.

  In the said invention, it is preferable that the said board | substrate is a member which has a positive electrode active material layer or a negative electrode active material layer. This is because it is useful in the production of lithium batteries.

  In this invention, there exists an effect that a Li-La-Ti-O type solid electrolyte material with a low resistance value can be obtained.

It is a schematic sectional drawing which shows an example of the lithium battery of this invention. It is a schematic sectional drawing which shows an example of the manufacturing method of the solid electrolyte material of this invention. It is a graph which shows the resistance value of the solid electrolyte material obtained in Examples 1-5.

  Hereinafter, the solid electrolyte material, the lithium battery, and the method for producing the solid electrolyte material of the present invention will be described in detail.

A. First, the solid electrolyte material of the present invention will be described. The solid electrolyte material of the present invention is represented by the general formula Li _3x (La _{(2 / 3-x) -a} M1 _a ) (Ti _1-b M2 _b ) O _3, where x is 0 <x <2/3. Where a satisfies 0 ≦ a ≦ 0.5, b satisfies 0 ≦ b ≦ 0.5, and M1 satisfies Sr, Na, Nd, Pr, Sm, Gd, Dy, Y, Eu. , Tb, Ba, and M2 is a group consisting of Mg, W, Mn, Al, Ge, Ru, Nb, Ta, Co, Zr, Hf, Fe, Cr, and Ga. At least one selected from the group consisting of a crystalline material and a thin film.

  According to the present invention, the Li—La—Ti—O-based solid electrolyte material having a low resistance value can be obtained because it has the above general formula, is crystalline, and is thin.

  One feature of the solid electrolyte material of the present invention is that it is crystalline. Patent Document 1 and Non-Patent Document 1 described above disclose amorphous solid electrolyte materials. In these documents, as an advantage of making the solid electrolyte material amorphous, it is possible to prevent an increase in resistance due to crystal grain boundaries. Thus, conventionally, it has been usual to form an amorphous solid electrolyte material in consideration of the presence of grain boundary resistance. In contrast, in the present invention, it was confirmed that even a crystalline solid electrolyte material can realize a resistance value close to that of an amorphous solid electrolyte material. In addition, it can confirm that the solid electrolyte material of this invention is crystalline by X-ray diffraction (XRD).

  One feature of the solid electrolyte material of the present invention is that it is in the form of a thin film. Patent Document 2 described above discloses a solid electrolyte material as a so-called bulk body. In the solid electrolyte material that is a bulk body, spaces are easily generated between crystal grains, and it is difficult to bond the crystal grains well. On the other hand, in this invention, it can be set as a thin-film dense solid electrolyte material by using the reactive vapor deposition method etc. which are mentioned later. Therefore, it is considered that the crystal grains can be bonded well and the grain boundary resistance can be suppressed.

  The thickness of the solid electrolyte material of the present invention is not particularly limited, but is preferably, for example, 10 nm or more, more preferably 50 nm or more, and further preferably 100 nm or more. On the other hand, the thickness of the solid electrolyte material is, for example, preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less.

Further, the solid electrolyte material of the present invention _is represented by _{Li 3x (La (2 / 3x} ) -a M1 a) (Ti 1-b M2 b) O 3. In the above general formula, x satisfies 0 <x <2/3. In the present invention, x preferably satisfies 0.07 ≦ x, and more preferably satisfies 0.07 <x. This is because a solid electrolyte material having a low resistance value can be obtained as described in the examples described later. Among these, in the present invention, it is more preferable that x satisfies 0.10 ≦ x. The resistance value of the solid electrolyte material of the present invention is based on the resistance value of the solid electrolyte material (Li _0.5 La _0.5 TiO ₃ , x = 0.17, amorphous) described in Non-Patent Document 1 described above. This is because it can be lowered. Assuming that the area (deposition area) of the solid electrolyte material described in Non-Patent Document 1 is 0.785 cm ² (equivalent to φ10 mm) as in the examples described later, the resistance value in that case is 4.6Ω. In the present invention, when x is 0.10 or more, the resistance value of the solid electrolyte material of the present invention can be made lower than 4.6Ω.

  On the other hand, in the present invention, x preferably satisfies x ≦ 0.17, and more preferably satisfies x <0.17. This is because a solid electrolyte material having a low resistance value can be obtained as described in the examples described later. In particular, in the present invention, x preferably satisfies x ≦ 0.16, and particularly preferably satisfies x ≦ 0.15. This is because the resistance value of the solid electrolyte material of the present invention can be made lower than 4.6Ω.

  In the above general formula, a satisfies 0 ≦ a ≦ 0.5. The reason why the upper limit of a is defined as 0.5 is that when a is larger than 0.5, the ratio of La becomes relatively small, and a stable perovskite structure may not be formed. In the above general formula, b satisfies 0 ≦ b ≦ 0.5. The reason for defining the upper limit of b as 0.5 is the same as in a. In the present invention, a or b may be 0, and a and b may be 0.

  In the above general formula, M1 is a metal that can be located at the same site as La in the crystal structure. Specifically, Sr, Na, Nd, Pr, Sm, Gd, Dy, Y, Eu, Tb, Ba Is at least one selected from the group consisting of

  In the above general formula, M2 is a metal that can be located at the same site as Ti in the crystal structure. Specifically, Mg, W, Mn, Al, Ge, Ru, Nb, Ta, Co, Zr, Hf , Fe, Cr, Ga. At least one selected from the group consisting of:

  The solid electrolyte material of the present invention is usually crystalline. The solid electrolyte material of the present invention preferably has a perovskite structure. It is because it can be set as a solid electrolyte material with high Li ion conductivity. In particular, the solid electrolyte material of the present invention is preferably a single-phase compound having a perovskite structure. It is because Li ion conductivity can be made higher.

  The solid electrolyte material of the present invention preferably has a low resistance value. Specifically, it is preferably less than 4.6Ω, more preferably 4.2Ω or less. Furthermore, the solid electrolyte material of the present invention can be used for any application that requires Li ion conductivity. Applications of the solid electrolyte material include batteries such as lithium batteries, sensors such as gas sensors, and the like. The method for producing the solid electrolyte material of the present invention will be described in detail in “C. Method for producing solid electrolyte material” described later.

B. Next, the lithium battery of the present invention will be described. The lithium battery of the present invention includes a positive electrode active material layer containing a positive electrode active material, a negative electrode active material layer containing a negative electrode active material, and a solid electrolyte formed between the positive electrode active material layer and the negative electrode active material layer A lithium battery containing a layer, wherein the solid electrolyte layer contains the solid electrolyte material described above.

  According to this invention, it can be set as a high output lithium battery by using the solid electrolyte material mentioned above.

FIG. 1 is a schematic cross-sectional view showing an example of the lithium battery of the present invention. A lithium battery 10 in FIG. 1 is formed between a positive electrode active material layer 1 containing a positive electrode active material, a negative electrode active material layer 2 containing a negative electrode active material, and a positive electrode active material layer 1 and a negative electrode active material layer 2. The solid electrolyte layer 3, the positive electrode current collector 4 for collecting the positive electrode active material layer 1, the negative electrode current collector 5 for collecting the negative electrode active material layer 2, and a battery case 6 for housing these members It has. The present invention is characterized in that the solid electrolyte layer 3 contains the solid electrolyte material described in the above “A. Solid electrolyte material”.
Hereinafter, the lithium battery of the present invention will be described for each configuration.

1. Solid electrolyte layer First, the solid electrolyte layer in the present invention will be described. The solid electrolyte layer in the present invention contains the above-described solid electrolyte material. The thickness range of the solid electrolyte layer is preferably the same as the thickness range of the solid electrolyte material described above.

2. Next, the positive electrode active material layer in the present invention will be described. The positive electrode active material layer in the present invention is a layer containing at least a positive electrode active material, and may contain at least one of a conductive material, a solid electrolyte material, and a binder as necessary. Examples of the positive electrode active material include LiCoO ₂ , LiMnO ₂ , Li ₂ NiMn ₃ O ₈ , LiVO ₂ , LiCrO ₂ , LiFePO ₄ , LiCoPO ₄ , LiNiO ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O _{2, and the} like. Can be mentioned.

  The positive electrode active material layer in the present invention may further contain a conductive material. By adding a conductive material, the conductivity of the positive electrode active material layer can be improved. Examples of the conductive material include acetylene black, ketjen black, and carbon fiber. The positive electrode active material layer may further contain a solid electrolyte material. By adding the solid electrolyte material, the Li ion conductivity of the positive electrode active material layer can be improved. Examples of the solid electrolyte material include an oxide solid electrolyte material and a sulfide solid electrolyte material. The positive electrode active material layer may further contain a binder. Examples of the binder include fluorine-containing binders such as polytetrafluoroethylene (PTFE). The thickness of the positive electrode active material layer is preferably in the range of 0.1 μm to 1000 μm, for example.

3. Next, the negative electrode active material layer in the present invention will be described. The negative electrode active material layer in the present invention is a layer containing at least a negative electrode active material, and may contain at least one of a conductive material, a solid electrolyte material, and a binder as necessary. Examples of the negative electrode active material include a metal active material and a carbon active material. Examples of the metal active material include In, Al, Si, and Sn. On the other hand, examples of the carbon active material include mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, and soft carbon.

  The conductive material, the solid electrolyte material, and the binder used for the negative electrode active material layer are the same as those in the positive electrode active material layer described above. Moreover, it is preferable that the thickness of a negative electrode active material layer exists in the range of 0.1 micrometer-1000 micrometers, for example.

4). Other Configurations The lithium battery of the present invention has at least the solid electrolyte layer, the positive electrode active material layer, and the negative electrode active material layer described above. Furthermore, it usually has a positive electrode current collector for collecting current of the positive electrode active material layer and a negative electrode current collector for collecting current of the negative electrode active material layer. Examples of the material for the positive electrode current collector include SUS, aluminum, nickel, iron, titanium, and carbon. Among them, SUS is preferable. On the other hand, examples of the material for the negative electrode current collector include SUS, copper, nickel, and carbon. Of these, SUS is preferable. In addition, the thickness and shape of the positive electrode current collector and the negative electrode current collector are preferably appropriately selected according to the use of the lithium battery. Moreover, the battery case of a general lithium battery can be used for the battery case used for this invention. Examples of the battery case include a SUS battery case.

5. Lithium Battery The lithium battery of the present invention may be a primary battery or a secondary battery, but among them, a secondary battery is preferable. This is because it can be repeatedly charged and discharged and is useful, for example, as an in-vehicle battery. Examples of the shape of the lithium battery of the present invention include a coin type, a laminate type, a cylindrical type, and a square type. Moreover, the manufacturing method of the lithium battery of this invention will not be specifically limited if it is a method which can obtain the lithium battery mentioned above, The method similar to the manufacturing method of a general lithium battery can be used. . For example, a power generation element is manufactured by sequentially pressing a material constituting the positive electrode active material layer, a material constituting the solid electrolyte layer, and a material constituting the negative electrode active material layer, and this power generation element is placed inside the battery case. Examples of the method include housing and caulking the battery case.

C. Next, a method for producing a solid electrolyte material of the present invention will be described. The method for producing a solid electrolyte material of the present invention is selected from the group consisting of Li, La, Ti, M1 (M1 is Sr, Na, Nd, Pr, Sm, Gd, Dy, Y, Eu, Tb, Ba). And M2 (M2 is at least one selected from the group consisting of Mg, W, Mn, Al, Ge, Ru, Nb, Ta, Co, Zr, Hf, Fe, Cr, and Ga). A raw material preparation step of preparing a raw material composed of a), a thin film formation step of forming a LiLaTiO thin film on a substrate by the reactive vapor deposition method using oxygen using the raw material, and heating the LiLaTiO thin film Therefore, it is represented by the general formula Li _3x (La _{(2 / 3-x) -a} M1 _a ) (Ti _1-b M2 _b ) O _3, where x satisfies 0 <x <2/3, and a Satisfies 0 ≦ a ≦ 0.5 The b satisfies 0 ≦ b ≦ 0.5, is crystalline and is characterized by comprising a heating process of forming a solid electrolyte material is a thin film shape, a.

  According to the present invention, a dense LiLaTiO thin film can be formed by using a reactive vapor deposition method, and a solid electrolyte material with high crystallinity can be formed by performing heat treatment. As a result, a Li—La—Ti—O-based solid electrolyte material having a low resistance value can be obtained.

FIG. 2 is a schematic cross-sectional view showing an example of a method for producing a solid electrolyte material of the present invention. In FIG. 2, first, a crucible 12 containing Li metal, La metal, and Ti metal and a substrate 13 are placed in a chamber 11. Next, the pressure in the chamber 11 is lowered to form a vacuum state. Thereafter, O ₂ plasma is generated, and at the same time, Li metal, La metal, and Ti metal are volatilized by a resistance heating method or an electron beam method. Thereby, the LiLaTiO thin film 14 is vapor-deposited on the substrate 13. Thereafter, the substrate 13 on which the LiLaTiO thin film 14 is vapor-deposited is heated in the air to form a crystalline and thin-film solid electrolyte material from the LiLaTiO thin film 14.
Hereafter, the manufacturing method of the solid electrolyte material of this invention is demonstrated for every process.

1. Raw Material Preparation Step First, the raw material preparation step in the present invention will be described. The raw material preparation step in the present invention is at least one selected from the group consisting of Li, La, Ti, M1 (M1 is Sr, Na, Nd, Pr, Sm, Gd, Dy, Y, Eu, Tb, Ba). And M2 (M2 is at least one selected from the group consisting of Mg, W, Mn, Al, Ge, Ru, Nb, Ta, Co, Zr, Hf, Fe, Cr, and Ga). It is a step of preparing a constituent material.

  In the present invention, simple metals such as Li, La, Ti, M1, and M2 are usually prepared. These simple metals preferably have high purity. This is because a solid electrolyte material with few impurities can be obtained. Usually, when obtaining a solid electrolyte material in which a in the general formula is 0, M1 is not used, and in obtaining a solid electrolyte material in which b in the general formula is 0, M2 is not used.

2. Thin Film Formation Step Next, the thin film formation step in the present invention will be described. The thin film forming step in the present invention is a step of forming a LiLaTiO thin film on a substrate by the reactive vapor deposition method using oxygen using the above raw materials.

In the present invention, a LiLaTiO thin film is formed by reactive vapor deposition. In this method, the LiLaTiO thin film is formed by volatilizing the raw material and reacting the volatilized raw material with oxygen. Examples of the method for volatilizing the raw material include a resistance heating method and an electron beam method. Examples of the method of reacting the volatilized raw material with oxygen include a method using oxygen plasma and a method using oxygen gas. Furthermore, in the present invention, reactive vapor deposition is preferably performed in a vacuum, and specifically, it is preferably performed in a vacuum of 1 × 10 ⁻¹⁰ mBar or less. This is because a dense thin film can be formed. The thickness of the LiLaTiO thin film can be controlled by the deposition time.

  In the present invention, a LiLaTiO thin film is formed on the substrate. The board | substrate in this invention is not specifically limited, It is preferable to select suitably according to the use of solid electrolyte material. For example, when a solid electrolyte material is used as a solid electrolyte layer of a lithium battery, a member having a positive electrode active material layer or a negative electrode active material layer is preferably used as a substrate.

3. Next, the heating process in the present invention will be described. The heating step in the present invention is represented by the general formula Li _3x (La _{(2 / 3-x) -a} M1 _a ) (Ti _1-b M2 _b ) O ₃ by heating the LiLaTiO thin film. Satisfies 0 <x <2/3, a satisfies 0 ≦ a ≦ 0.5, b satisfies 0 ≦ b ≦ 0.5, and is a crystalline, thin-film solid electrolyte material. It is a process of forming.

  In the present invention, a solid electrolyte material having a crystal phase represented by the above general formula can be obtained by heating a LiLaTiO thin film. The heating temperature is preferably a temperature equal to or higher than the crystallization temperature of the crystal phase represented by the above general formula, and is preferably in the range of 600 ° C to 900 ° C, for example. The heating time is preferably in the range of 0.5 hours to 6 hours, for example. Moreover, as a method of heating a LiLaTiO thin film, the method of using a baking furnace etc. can be mentioned, for example. Furthermore, the atmosphere for heating the LiLaTiO thin film may be an air atmosphere or an inert gas atmosphere.

  In the present invention, the heating process may be performed after the thin film forming process, or the heating process may be performed simultaneously with the thin film forming process. In the latter case, it is preferable to heat the substrate to a desired temperature during thin film formation.

4). Others Since the solid electrolyte material obtained by the present invention is the same as the contents described in the above-mentioned “A. Solid electrolyte material”, description thereof is omitted here. Moreover, in this invention, the solid electrolyte material characterized by obtained by the manufacturing method of the solid electrolyte material mentioned above can be provided.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Example 1]
First, as raw materials, lithium metal (ribbon, purity 99.9%, manufactured by Sigma Aldrich), lanthanum metal (purity 99.9%, manufactured by Sigma Aldrich) and titanium metal (slug, purity 99.98%, Alfa Aesar) Prepared). Next, lithium metal was placed in a 40 cm ³ pyrolytic boron nitride (PBN) crucible and placed in the chamber. Next, each of lanthanum metal and titanium metal was put into a 40 cm ³ pyrolytic graphite crucible and similarly placed in the chamber. In addition, a Si / SiO ₂ / Ti / Pt laminate (manufactured by Nova Electronic Materials) was used as the substrate, the deposition area was 0.785 cm ² (equivalent to φ10 mm), and the distance from the raw material to the substrate was 500 mm. Next, a high vacuum of 1 × 10 ⁻¹⁰ mBar or less was set in the chamber.

  Then, resistance heating (Knudsen Cells) is performed on the crucible containing lithium metal to volatilize lithium, and at the same time, the electron beam irradiation is applied to the crucible containing lanthanum metal and the crucible containing titanium metal. And lanthanum metal and titanium metal were volatilized. In addition, a LiLaTiO thin film was deposited on the substrate by generating oxygen plasma in the chamber using an oxygen plasma generator (Oxford Applied Research, RF source, HD25) and reacting with the volatilized raw material. The deposition time was 60 minutes.

Thereafter, the LiLaTiO thin film deposited on the substrate was heated in the atmosphere at 750 ° C. for 3 hours to obtain a thin-film solid electrolyte material (thickness: 100 nm). When the XRD measurement (CuK (alpha) use) was performed with respect to the obtained solid electrolyte material, it was confirmed that it is crystalline. Moreover, when ICP analysis (inductively coupled plasma analysis) was performed on the obtained solid electrolyte material, the composition was Li _0.21 La _0.60 TiO ₃ (x = 0.07). From these results, it was confirmed that the obtained solid electrolyte material had a perovskite structure.

[Examples 2 to 5]
A thin-film solid electrolyte material was obtained in the same manner as in Example 1 except that the amount of metal volatilized from the crucible was appropriately adjusted with a shutter. The compositions of the solid electrolyte materials obtained in Examples 2 to 5 are Li _0.30 La _0.57 TiO ₃ (x = 0.10) and Li _0.36 La _0.55 TiO ₃ (x = 0, respectively). .12), Li _0.45 La _0.52 TiO ₃ (x = 0.15), Li _0.50 La _0.50 TiO ₃ (x = 0.17).

[Evaluation]
The resistance values of the solid electrolyte materials obtained in Examples 1 to 5 were measured. First, platinum was vapor-deposited on the surface of the solid electrolyte material formed on the substrate to produce a symmetrical cell of Pt / solid electrolyte material / Pt. Next, the resistance value of the solid electrolyte material was measured by the AC impedance method. The results are shown in Table 1 and FIG.

As shown in Table 1 and FIG. 3, Examples 1 to 5 all exhibited low resistance values. Among them, in Examples 2 to 4, the resistance value (4.4) of the solid electrolyte material (Li _0.5 La _0.5 TiO ₃ , x = 0.17, amorphous) described in Non-Patent Document 1 described above. 6 Ω). In particular, when x satisfies 0.11 ≦ x ≦ 0.14, the resistance value can be reduced to half or less of the conventional resistance value.

[Reference example]
A predetermined amount of Li ₂ CO ₃ , La ₂ O ₃ and TiO ₂ was weighed and mixed with a planetary ball mill. Thereafter, it was calcined in a platinum crucible at 800 ° C. for 4 hours. Next, after calcining the calcined body, it was calcined again at 1150 ° C. for 12 hours. Next, the calcined body was pulverized and molded into a pellet, and then fired under the conditions of 1250 ° C. and 12 hours. As a result, a sintered bulk solid electrolyte material (Li _0.5 La _0.5 TiO ₃ (x = 0.17), thickness 10 μm) was obtained. The resistance value of this solid electrolyte material was measured by the same method as described above, and as a result, it was 8.2Ω.

DESCRIPTION OF SYMBOLS 1 ... Positive electrode active material layer 2 ... Negative electrode active material layer 3 ... Solid electrolyte layer 4 ... Positive electrode collector 5 ... Negative electrode collector 6 ... Battery case 10 ... Lithium battery 11 ... Chamber 12 ... Crucible 13 ... Substrate 14 ... LiLaTiO thin film

Claims (10)

It is represented by the general formula Li _3x (La _{(2 / 3-x) -a} M1 _a ) (Ti _1-b M2 _b ) O ₃ ,
X satisfies 0 <x <2/3, a satisfies 0 ≦ a ≦ 0.5, b satisfies 0 ≦ b ≦ 0.5,
The M1 is at least one selected from the group consisting of Sr, Na, Nd, Pr, Sm, Gd, Dy, Y, Eu, Tb, Ba,
The M2 is at least one selected from the group consisting of Mg, W, Mn, Al, Ge, Ru, Nb, Ta, Co, Zr, Hf, Fe, Cr, and Ga.
A solid electrolyte material characterized by being crystalline and in the form of a thin film.   The solid electrolyte material according to claim 1, wherein x satisfies 0.07 <x <0.17.   The solid electrolyte material according to claim 2, wherein the x satisfies 0.10 ≦ x ≦ 0.15.   The solid electrolyte material according to any one of claims 1 to 3, wherein a and b are 0. Lithium battery comprising a positive electrode active material layer containing a positive electrode active material, a negative electrode active material layer containing a negative electrode active material, and a solid electrolyte layer formed between the positive electrode active material layer and the negative electrode active material layer Because
The said solid electrolyte layer contains the solid electrolyte material as described in any one of Claim 1- Claim 4. The lithium battery characterized by the above-mentioned. Li, La, Ti, M1 (M1 is at least one selected from the group consisting of Sr, Na, Nd, Pr, Sm, Gd, Dy, Y, Eu, Tb, Ba), and M2 (M2 Is at least one selected from the group consisting of Mg, W, Mn, Al, Ge, Ru, Nb, Ta, Co, Zr, Hf, Fe, Cr, and Ga). A preparation process;
A thin film forming step of forming a LiLaTiO thin film on a substrate by a reactive vapor deposition method using oxygen using the raw material;
By heating the LiLaTiO thin film, it is represented by the general formula Li _3x (La _{(2 / 3-x) -a} M1 _a ) (Ti _1-b M2 _b ) O _3, where x is 0 <x <2 / 3 wherein the a satisfies 0 ≦ a ≦ 0.5, the b satisfies 0 ≦ b ≦ 0.5, and is a crystalline, thin film-like solid electrolyte material;
A method for producing a solid electrolyte material, comprising:   The method for producing a solid electrolyte material according to claim 6, wherein x satisfies 0.07 <x <0.17.   The method for producing a solid electrolyte material according to claim 7, wherein x satisfies 0.10 ≦ x ≦ 0.15.   The solid electrolyte material production according to any one of claims 6 to 8, wherein in the thin film formation step, the LiLaTiO thin film is formed by a reactive vapor deposition method using oxygen plasma. Method.   The method for producing a solid electrolyte material according to any one of claims 6 to 9, wherein the substrate is a member having a positive electrode active material layer or a negative electrode active material layer.

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