JP5499817B2 - Lithium ion conductor and solid lithium battery - Google Patents

Description

  The present invention relates to a lithium ion conductor and a solid lithium battery using the same.

  In recent years, with the rapid spread of information-related equipment such as personal computers, video cameras, and mobile phones, and communication equipment, development of batteries that are used as power sources has been regarded as important. Also in the automobile industry, development of high-power and high-capacity batteries for electric vehicles and hybrid vehicles is underway. Among various batteries, lithium secondary batteries are attracting attention because of their high energy density and output.

A typical lithium secondary battery includes a positive electrode layer containing a positive electrode active material, a negative electrode layer containing a negative electrode active material, and an electrolyte layer interposed between the positive electrode layer and the negative electrode layer.
As a lithium secondary battery using a flammable organic electrolyte as an electrolyte layer disposed between the positive electrode layer and the negative electrode layer, in addition to liquid leakage, safety measures assuming short circuit or overcharge are indispensable. In particular, high-power, high-capacity batteries are required to further improve safety. Therefore, it has been proposed to use a nonflammable ceramic solid electrolyte (inorganic solid electrolyte) such as a sulfide-based solid electrolyte or an oxide-based solid electrolyte as the electrolyte.

On the other hand, as an electrode active material constituting the electrode layer (positive electrode layer or negative electrode layer), for example, as a positive electrode active material of a lithium secondary battery, LiCoO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , Li ₃ V ₂ Oxide active materials such as (PO ₄ ) ₃ and LiCoMnO ₄ are used. In addition, as a negative electrode active material of a lithium secondary battery, an oxide active material such as lithium-titanium oxide typified by Li ₄ Ti ₅ O ₁₂ , carbon, or the like is used.
In general, oxide active materials used in lithium secondary batteries tend to have low lithium ion conductivity and electronic conductivity. Therefore, in addition to these oxide active materials, the electrode layer improves the conductivity of the electrode layer (for example, a conductive carbon material) and the ion conductivity of the electrode layer, if necessary. Generally, an electrode mixture to which an electrolyte (lithium ion conductor) is added is used.

In a liquid lithium secondary battery in which the electrolyte layer is composed of an electrolyte solution, the electrode layer is immersed in the electrolyte solution, so that the electrolyte solution penetrates into the electrode layer and the electrolyte solution exists around the active material of the electrode layer Will do. That is, in a liquid lithium secondary battery, the lithium ion conductivity of the electrode layer is ensured. Therefore, in general, a conductive additive such as a conductive carbon material is added to the active material as an electrode mixture. Is used.
On the other hand, in a solid lithium secondary battery in which the electrolyte layer is composed of a solid electrolyte, there is no permeation of the electrolyte solution as in the electrode layer of the liquid lithium secondary battery. For this reason, in a solid lithium secondary battery, it has been proposed to form an electrode layer using an electrode mixture in which a solid electrolyte (lithium ion conductor) is added in addition to a conductive additive.

  However, auxiliary agents such as a conductive additive and an electrolyte in the electrode layer are very effective for improving the output characteristics of the battery, but are components that do not contribute to power generation, and thus reduce the energy density of the battery. There is a problem.

  For example, Patent Document 1 discloses the production of a carbon material for an electrode including a step of activating a mixture of a carbonaceous main material and a conductive additive for the purpose of providing an electrochemical device having a small internal resistance and a large capacitance. A method is disclosed. In Patent Document 1, the carbon material and the conductive auxiliary are mixed in advance after the activation treatment is performed on the carbon material, and then the activation is performed. It is described that is achieved. In Patent Document 1, carbon materials such as carbon black, carbon nanotubes, graphite, and fullerene are described as preferable conductive assistants.

In Patent Document 2, as a cause of low capacity in an all-solid-state lithium battery, since lithium ions are more easily attracted to oxide ions in the positive electrode layer than sulfide ions in the solid electrolyte layer, sulfide solids It is described that a lithium ion-deficient layer (depletion layer) is formed on the positive electrode layer side of the electrolyte. The invention described in Patent Document 2 is intended to provide a lithium secondary battery having high capacity and excellent productivity, and includes a positive electrode layer formed by a vapor deposition method, a sulfide solid electrolyte layer, In the meantime, the lithium secondary battery includes a buffer layer for buffering the deviation of lithium ions in the vicinity of the interface between these two layers.
Patent Document 2 exemplifies lithium lanthanum titanium oxide as the lithium ion conductive oxide constituting the buffer layer. Patent Document 2 describes that the electronic conductivity of the buffer layer is preferably 1 × 10 ⁻⁵ S / cm or less, and lithium lanthanum titanium oxide actually used in the examples. The electronic conductivity of the object is 1 × 10 ⁻⁸ S / cm.

International Publication No. WO2007 / 119885 JP 2009-245913 A

  The present invention has been accomplished in view of the above circumstances, and an object of the present invention is to provide a lithium ion conductor having both lithium ion conductivity and electronic conductivity. Another object of the present invention is to provide a solid lithium battery using the lithium ion conductor and having high output characteristics and energy density.

Lithium ion conductor of the present invention, 1.0 × 10 -5 Ri Do lithium lanthanum titanium oxide having a high electronic conductivity than ^{S / cm,} X-ray photoelectron spectroscopy of the lithium lanthanum titanium oxide (XPS) The bond energy of the 1s orbit of oxygen (O) determined by the above has a first peak in the range of 528 to 530 eV .
Since the lithium ion conductor of the present invention has high electron conductivity as described above together with lithium ion conductivity, it can be used as a lithium ion conduction aid and an electron conduction aid. That is, by using the lithium ion conductor of the present invention, it is possible not to use a conductive aid in the electrode layer or to reduce the content of the conductive aid in the electrode layer. Therefore, according to the present invention, in a solid lithium battery using a lithium ion conductive solid electrolyte, it is possible to improve battery characteristics and energy density.

The solid lithium battery of the present invention is a solid lithium battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer and / or the negative electrode layer comprises: It includes at least an electrode active material and the lithium ion conductor of the present invention.
The solid lithium battery of the present invention has a high energy density as well as excellent battery characteristics by using the lithium ion conductor of the present invention having the above electronic conductivity.

  According to the present invention, it is possible to provide a lithium ion conductor having electronic conductivity as well as lithium ion conductivity. Therefore, according to the present invention, it is possible to provide a solid lithium battery using the lithium ion conductor and having high output characteristics and energy density.

The result of the XPS analysis in Example 1 and Comparative Example 1 is shown.

The lithium ion conductor of the present invention is characterized by comprising lithium lanthanum titanium oxide having an electronic conductivity higher than 1.0 × 10 ⁻⁵ S / cm.

As described above, the addition of an auxiliary agent such as a conductive additive or a solid electrolyte to the electrode layer has a problem that the energy density of the solid lithium battery is reduced, although the output improvement effect of the solid lithium battery can be obtained. As a result of studying the above problem, the present inventor improves the above problem by using a solid electrolyte having electronic conductivity as a solid electrolyte added as a lithium ion conduction aid for the electrode layer in a lithium ion battery. I got the knowledge that I can do it. Further, as a result of extensive studies, the present inventor has obtained lithium lanthanum titanium oxide having a first peak in the bond energy of 1s orbit of oxygen (O) determined by X-ray photoelectron spectroscopy (XPS) in the range of 528 to 530 eV. It was found that the product has excellent electron conductivity exceeding 1.0 × 10 ⁻⁵ S / cm together with lithium ion conductivity, and the present invention has been completed.

The lithium ion conductor of the present invention is a lithium lanthanum titanium oxide represented by an average composition formula Li _x La _{(2-x) / 3} TiO ₃ (x = 0.1 to 0.5). In the above average composition formula, x is preferably 0.3 to 0.5, particularly preferably 0.5.

Among lithium lanthanum titanium oxides, those having a first peak (the largest peak) in the range of 528 to 530 eV in the binding energy of the oxygen (O) 1s orbit obtained by X-ray photoelectron spectroscopy (XPS method) It has been confirmed by the present inventor that the electron conductivity is higher than 1.0 × 10 ⁻⁵ S / cm (see Example 1). On the other hand, even if it is a lithium lanthanum titanium oxide, the lithium lanthanum titanium oxide which shows the spectrum which does not have the said characteristic has the electronic conductivity of 1.0 * 10 < ^-5 > S / cm or less. It has been confirmed by the inventor (see Comparative Example 1).

  The XPS analysis of the lithium ion conductor can be performed according to a general method. Usually, XPS analysis is performed on a green compact obtained by pressure-forming powdered lithium lanthanum titanium oxide.

The lithium ion conductor of the present invention preferably has a lithium ion conductivity of 1.0 × 10 ⁻⁶ S / cm or more, particularly preferably 1.0 × 10 ⁻⁵ S / cm or more, and more preferably 1 It has a lithium ion conductivity of not less than 0.0 × 10 ⁻⁴ S / cm. The lithium ion conductivity of the lithium ion conductor can be measured by a known method. For example, lithium ion transport number measurement methods such as a complex impedance method can be used alone or in combination of two or more.

The lithium ion conductor of the present invention has an electron conductivity higher than 1.0 × 10 ⁻⁵ S / cm together with the lithium ion conductivity. According to the present invention, it is possible to obtain lithium ion conductivity that further exhibits an electron conductivity of 6.0 × 10 ⁻⁵ S / cm or more. The electronic conductivity of the lithium ion conductor can be measured using, for example, a powder resistance measuring device, specifically, MCP-PD51 manufactured by Mitsubishi Chemical Analytech Co., Ltd.

The method for producing the lithium ion conductor of the present invention is not particularly limited. For example, a method of synthesizing by a vapor phase method such as a chemical vapor phase synthesis method or a physical vapor phase synthesis method using a raw material solution containing a constituent element of lithium lanthanum titanium oxide can be given. Specifically, by spraying a raw material solution containing a lithium compound as a lithium supply source, a lanthanum compound as a lanthanum supply source, and a titanium compound as a titanium supply source together with oxygen gas (reaction gas) to a high temperature reaction field Lithium lanthanum titanium oxide particles can be produced (flame method).
Hereinafter, a method for producing lithium lanthanum titanium oxide by the flame method will be described.

In the flame method, the high temperature reaction field can be formed by, for example, plasma or a burner. The specific temperature of the high temperature reaction field is not particularly limited.
Moreover, it does not specifically limit as a lithium compound used as a lithium supply source, a lanthanum compound used as a lanthanum supply source, and a titanium compound used as a titanium supply source.
For example, lithium nitrate etc. are mentioned as a lithium compound. Examples of lanthanum compounds include lanthanum nitrate. Moreover, as a titanium compound, titanium lactate etc. are mentioned, for example. Of the lithium compound, the lanthanum compound, and the titanium oxide, at least one, preferably two or more are preferably inorganic oxides.

Two or more of the lithium compound, the lanthanum compound, and the titanium compound may be a common compound. For example, a lithium titanium compound serving both as a lithium supply source and a titanium supply source may be used.
Moreover, the said raw material solution may contain the compound used as an oxygen supply source other than a lithium compound, a lanthanum compound, and a titanium compound.

  In the raw material solution, the solvent for dissolving the lithium compound, the lanthanum compound, and the titanium compound is not particularly limited as long as each compound to be used can be dissolved, but an inorganic solvent is preferable.

The ratio of each compound in the raw material solution may be appropriately selected in consideration of the composition of each compound used, the composition of the target lithium lanthanum titanium oxide, and the like.
In addition, the supply rate of the raw material solution, the supply rate of the oxygen gas that is the reaction gas, and the like may be appropriately determined.
For production of lithium lanthanum titanium oxide particles by the flame method, for example, a nano creator (model: FCM-MINI) manufactured by Hosokawa Micron Corporation can be used.

As described above, the lithium ion conductor of the present invention has an electron conductivity higher than 1.0 × 10 ⁻⁵ S / cm along with the lithium ion conductivity. Therefore, the lithium ion conductor of the present invention functions as a lithium ion conduction aid and a conduction aid in the electrode layer of the lithium battery. Therefore, by using the lithium ion conductor of the present invention, the electron conductivity of the electrode layer can be ensured without using a conductive auxiliary agent, or the electron in the electrode layer can be reduced even if the amount of the conductive auxiliary agent is reduced. It is possible to ensure conductivity. That is, according to the present invention, it is possible to improve the output characteristics of the battery without reducing the energy density.

The lithium ion conductor of the present invention can be used in a wide variety of applications in various fields. Here, the application form will be described taking the solid lithium battery of the present invention using the lithium ion conductor of the present invention as a lithium ion conduction aid and an electron conduction aid in the electrode layer as an example.
The solid lithium battery of the present invention is a solid lithium battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer and / or the negative electrode layer is at least A solid lithium battery comprising an electrode active material and the lithium ion conductor of the present invention.

In a general solid lithium battery, a positive electrode layer and a negative electrode layer (hereinafter, collectively referred to as an electrode layer) include at least a positive electrode active material or a negative electrode active material (hereinafter, collectively referred to as an electrode active material). If necessary, a conductive assistant, a solid electrolyte (ionic conductive assistant), and a binder component are also included. The solid lithium battery of the present invention is characterized in that at least one of the positive electrode layer and the negative electrode layer contains the lithium ion conductor of the present invention described above together with the electrode active material. As described above, the lithium ion conductor of the present invention functions as a lithium ion ion conduction aid and a conduction aid.
Hereinafter, each layer constituting the solid lithium battery will be described.

First, the positive electrode layer will be described. The positive electrode layer is a layer containing at least a positive electrode active material.
Examples of the positive electrode active material include LiCoO ₂ , LiNiO ₂ , LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , LiVO ₂ , LiCrO ₂ , LiMn ₂ O ₄ , LiCoMnO ₄ , Li ₂ NiMn ₃ O ₈ , Examples include LiNi _0.5 Mn _1.5 O ₄ , LiCoPO ₄ , LiMnPO ₄ , LiFePO _{4 and the} like. The shape of the positive electrode active material is preferably particulate. The average particle diameter of the particulate positive electrode active material is preferably in the range of, for example, 1 nm to 100 μm, and more preferably in the range of 10 nm to 30 μm. Furthermore, the specific surface area of the particulate positive electrode active material is preferably within a range of, for example, 0.1m ² / g~10m ² / g.
Note that there is no clear distinction between the positive electrode active material and the negative electrode active material, and the charge / discharge potential and oxidation-reduction potential of two types of compounds are compared. A battery having an arbitrary voltage can be formed by combining the negative electrode active materials with a high potential. Here, a positive electrode active material and a negative electrode active material are illustrated as examples of the combination of the positive electrode active material and the negative electrode active material.

The content of the positive electrode active material contained in the positive electrode layer is preferably larger from the viewpoint of capacity, for example, within the range of 99.9 to 50% by weight, particularly within the range of 99.9 to 80% by weight. Is preferred.
The positive electrode layer may contain the lithium ion conductor of the present invention, other conductive auxiliary agent, and lithium ion conductive auxiliary agent (solid electrolyte) as necessary.
Since the lithium ion conductor of the present invention has been described above, the description thereof is omitted here. The content of the lithium ion conductor contained in the positive electrode layer is preferably less as long as desired electronic conductivity and lithium ion conductivity can be secured, for example, in the range of 50 to 0.1% by weight, particularly 20 to 0. It is preferable to be within the range of 1% by weight.

In addition to the lithium ion conductor of the present invention or with the lithium ion conductor of the present invention, other conductive auxiliary agents and lithium ion conductive auxiliary agents are not particularly limited. For example, conductive assistants include conductive carbon materials such as acetylene black, carbon black, coke, carbon fiber, and graphite. Examples of the lithium ion conduction aid include oxide solid electrolyte materials and sulfide solid electrolyte materials, and sulfide solid electrolyte materials are particularly preferable. As a specific material of the lithium ion conduction aid, for example, a solid electrolyte constituting a solid electrolyte layer described later can be used.
As described above, by using the lithium ion conductor of the present invention, the electron conductivity in the electrode layer can be ensured without using any other conductive aid or reducing the amount of use. When using another conductive support agent with the lithium ion conductor of this invention, although the quantity of this conductive support agent is based also on the combination of a lithium ion conductor and another conductive support agent, it is 20 to 0 weight%, for example. It is preferable to be within the range.

  The positive electrode layer may further contain a binder component. The binder component is preferably chemically and electrically stable. Specifically, the binder component is a fluorine-based binder component such as polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE), and styrene butadiene. Examples thereof include rubber-based binder components such as rubber. The content of the binder component in the positive electrode layer is preferably less as long as the positive electrode active material and the like can be stably fixed, and is preferably in the range of 20 to 0% by weight, for example.

  The thickness of the positive electrode layer varies greatly depending on the configuration of the solid lithium battery, but is preferably in the range of, for example, 0.1 μm to 1000 μm.

  Next, the negative electrode layer will be described. The negative electrode layer is a layer containing at least a negative electrode active material.

Examples of the negative electrode active material include a metal active material and a carbon active material. Examples of the metal active material include Li, 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 shape of the negative electrode active material may be, for example, a film shape or a particle shape. When a film-like negative electrode active material is used, the negative electrode active material itself is usually the negative electrode layer. Moreover, the average particle diameter of the particulate negative electrode active material is, for example, preferably in the range of 1 nm to 100 μm, and more preferably in the range of 10 nm to 30 μm. Furthermore, the specific surface area of the negative electrode active material of particulate is preferably within the range of, for example, 0.1m ² / g~10m ² / g.

In the case where the negative electrode active material is in the form of particles, the negative electrode layer may include, in addition to the particulate negative electrode active material, the lithium ion conductor of the present invention, and other conductive auxiliary agents and lithium ion conductive auxiliary agents as necessary. (Solid electrolyte) and a binder component may be included.
In this case, the content of the negative electrode active material contained in the negative electrode layer is preferably larger from the viewpoint of capacity, for example, in the range of 99.9 to 50% by weight, particularly in the range of 99.9 to 80% by weight. It is preferable that Further, the content of the lithium ion conductor contained in the negative electrode layer is preferably smaller as long as desired electronic conductivity and lithium ion conductivity can be secured, for example, in the range of 50 to 0.1% by weight, in particular, 20 It is preferable to be within the range of ˜0.1% by weight. In addition, in the negative electrode layer, when using other conductive auxiliary together with the lithium ion conductor of the present invention, the amount of the conductive auxiliary depends on the combination of the lithium ion conductor and the other conductive auxiliary. It is preferably within the range of 20 to 0% by weight. Further, the content of the binder component in the negative electrode layer is preferably less as long as the negative electrode active material and the like can be stably fixed, and is preferably in the range of, for example, 20 to 0% by weight.
In addition, about the lithium ion conductor of this invention used for a negative electrode layer, a conductive support agent, a lithium ion conductive support agent, and a binder component, since it is the same as that used for the said positive electrode layer, description here is abbreviate | omitted.

  The thickness of the negative electrode layer varies greatly depending on the configuration of the solid lithium battery, but is preferably in the range of 0.1 μm to 1000 μm, for example.

  Next, the solid electrolyte layer will be described. The solid electrolyte layer is a layer formed between the positive electrode layer and the negative electrode layer. Li ion conduction between the positive electrode active material and the negative electrode active material is performed through the solid electrolyte contained in the solid electrolyte layer.

The solid electrolyte layer is a layer made of a solid electrolyte material. Examples of the solid electrolyte material include an oxide solid electrolyte material and a sulfide solid electrolyte material having lithium ion conductivity. Of these, a sulfide solid electrolyte material is preferable. This is because a high output battery with high Li ion conductivity can be obtained.
Examples of the sulfide solid electrolyte material having lithium ion conductivity include a Li ₂ S—P ₂ S ₅ compound, a Li ₂ S—SiS ₂ compound, and a Li ₂ S—GeS ₂ compound. The Li ₂ S—P ₂ S ₅ compound means a sulfide solid electrolyte material using Li ₂ S and P ₂ S ₅ . The same applies to other compounds.
Examples of the lithium ion conductive oxide solid electrolyte material include Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ , Li _0.5 La _0.5 TiO ₃ , and Li ₅ La ₃ TaO. ₁₂ , Li _1.5 Al _0.5 Ti _1.5 (PO ₄ ) _{3 and the} like.

  The average particle diameter of the solid electrolyte material is, for example, preferably in the range of 1 nm to 100 μm, and more preferably in the range of 10 nm to 30 μm.

  The thickness of the solid electrolyte layer varies greatly depending on the configuration of the solid lithium battery. For example, the thickness is preferably in the range of 0.1 μm to 1000 μm, and more preferably in the range of 0.1 μm to 300 μm.

  The solid lithium battery has at least the positive electrode layer, the electrolyte layer, and the negative electrode layer described above. Furthermore, it usually has a positive electrode current collector for collecting current of the positive electrode layer and a negative electrode current collector for collecting current of the negative electrode 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, as a battery case which accommodates a solid lithium battery, the battery case of a general lithium battery can be used. Examples of the battery case include a SUS battery case.

  In addition, although the solid lithium battery provided with the solid electrolyte layer has been described here, the lithium ion conductor of the present invention has an electrolyte layer of a form other than the solid electrolyte layer such as a liquid electrolyte layer and a gel electrolyte layer as the electrolyte layer. It can also be used for a lithium battery provided. When the electrolyte layer is a liquid electrolyte layer, the electrode layer preferably contains a binder component. This is because sliding of the electrode active material from the electrode layer can be effectively suppressed.

The liquid electrolyte layer is usually a layer using a non-aqueous electrolyte. The non-aqueous electrolyte of a lithium battery usually contains a lithium salt and a non-aqueous solvent. Examples of the lithium salt include inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO _4, and LiAsF ₆ ; and LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , An organic lithium salt such as LiC (CF ₃ SO ₂ ) ₃ can be used. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), butylene carbonate, γ-butyrolactone, sulfolane, acetonitrile, Examples include 1,2-dimethoxymethane, 1,3-dimethoxypropane, diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, and mixtures thereof. The concentration of the lithium salt in the non-aqueous electrolyte is, for example, in the range of 0.5 mol / L to 3 mol / L. Note that a low-volatile liquid such as an ionic liquid may be used as the nonaqueous electrolytic solution.

The gel electrolyte layer can be obtained, for example, by adding a polymer to the non-aqueous electrolyte and gelling. Specifically, gelation can be performed by adding a polymer such as polyethylene oxide (PEO), polyacrylonitrile (PAN), or polymethyl methacrylate (PMMA) to the non-aqueous electrolyte.
The solid lithium battery of the present invention is not limited to the structure described above.

[Preparation of Lithium Ion Conductor Li _0.5 La _0.5 TiO ₃ ]
Example 1
First, a lithium nitrate solution, a lanthanum nitrate solution, and a titanium lactate solution were mixed to prepare an inorganic raw material solution.
Next, propane gas 1 L / min and oxygen gas 5 L / min are combusted to form a flame, and the inorganic raw material solution is supplied into the flame together with oxygen gas 12 L / min at 2 g / min. (Gray, Li _0.5 La _0.5 TiO ₃ ) was obtained.

About the obtained particle | grains, the specific surface area measurement, the average particle diameter measurement, the electronic conductivity measurement, and the XPS measurement were performed. The results are shown in Table 1 and FIG.
The specific surface area of the particles was measured by a one-point BET method using nitrogen adsorption.
Moreover, the electronic conductivity measurement of particle | grains was performed with respect to the green compact obtained by press-molding particle | grains. Specifically, the electron conductivity was measured using a powder resistance measurement system (manufactured by Mitsubishi Analytech Co., Ltd., MCP-PD51, 4 probe, ring electrode) under a pressure application condition of 20 MPa.

(Comparative Example 1)
First, a lithium naphthenate solution, a lanthanum 2-ethylhexanoate solution, a titanium tetra-2-ethylhexoxide solution, and mineral spirit were mixed to prepare an organic raw material solution.
Next, propane gas 1 L / min and oxygen gas 5 L / min are combusted to form a flame, and the organic raw material solution is supplied into the flame at 3 g / min together with oxygen gas 9 L / min. (White, Li _0.5 La _0.5 TiO ₃ ) was obtained.

  About the obtained particle | grains, it carried out similarly to Example 1, and performed the specific surface area measurement, the average particle diameter measurement, the electronic conductivity measurement, and the XPS measurement. The results are shown in Table 1 and FIG.

[result]
As shown in Table 1, the electronic conductivity of the Li _0.5 La _0.5 TiO ₃ particles of Example 1 is 6.9 × 10 ⁻⁵ S / cm, and Li _0.5 La _{0 of} Comparative Example 1 _.5 Electron conductivity was significantly higher (10 times or more) compared to TiO ₃ particles.
Further, as shown in FIG. 1, XPS analysis was performed on the Li _0.5 La _0.5 TiO ₃ particles of Example 1 and Comparative Example 1, and as a result, Li _0.5 La _0.5 TiO _{3 of} Example 1 was obtained. The particles were confirmed to have a first peak in the binding energy of the oxygen (O) 1s orbital near 529 eV. This peak around 529 eV is attributed to O ²⁻ . In contrast, in the Li _0.5 La _0.5 TiO ₃ particles of Comparative Example 1, a peak near 529 eV attributed to O ²⁻ was observed as a shoulder of a peak near 533 eV attributed to —OH.
That is, from the result of the electron conductivity measurement and the result of XPS analysis, lithium lanthanum titanium oxide having a first peak in the oxygen (O) 1s orbital bond energy in the range of 528 to 530 eV is 1.0 × 10 6. It was confirmed to have an electron conductivity higher than ⁻⁵ S / cm.

Claims (2)

Ri Do lithium lanthanum titanium oxide having a high electronic conductivity than 1.0 × ¹⁰ -5 S / cm,
Lithium ion conduction characterized in that the bond energy of the 1s orbit of oxygen (O) obtained by X-ray photoelectron spectroscopy (XPS) of the lithium lanthanum titanium oxide has a first peak in the range of 528 to 530 eV. body. A solid lithium battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer,
2. The solid lithium battery, wherein the positive electrode layer and / or the negative electrode layer includes at least an electrode active material and the lithium ion conductor according to claim 1 .

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