JP2012094378A - Solid-electrolyte sintered body, and all-solid lithium battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-electrolyte sintered body having a high sintered density.SOLUTION: The solid-electrolyte sintered body contains a solid electrolyte material having Li ion conductivity and capable of forming a stable covalent bond, and a crystalline material capable of forming a stable ionic bond, and includes no heterogeneous phase at the interface between the solid electrolyte material and the crystalline material. The average grain size of the crystalline material is equal to that of the solid electrolyte material, or smaller.

Description

  The present invention relates to a solid electrolyte sintered body used for, for example, an all-solid lithium battery, and more particularly to a solid electrolyte sintered body having an improved sintered density.

  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. On the other hand, an all-solid lithium battery in which the electrolyte is changed to a solid electrolyte layer to make the battery all solid does not use a flammable organic solvent in the battery. It is considered to be excellent in productivity.

In order to increase the output of such an all solid lithium battery, studies have been conventionally made to improve the Li ion conductivity of the solid electrolyte used in the solid electrolyte layer. For example, Non-Patent Document 1 discloses a solid electrolyte sintered body obtained by adding 5 to 15% SiO ₂ in volume fraction to Li _0.5 La _0.5 TiO ₃ which is a Li ion conductive solid electrolyte. Has been. Non-Patent Document 2 discloses a composite solid electrolyte composed of LiI which is a Li ion conductive solid electrolyte and mesoporous SiO ₂ . These are intended to improve Li ion conductivity by mixing SiO ₂ with a solid electrolyte.

On the other hand, in Patent Document 1, a structural _{member, LiAlX n (OY) 4-} n (X is an electron withdrawing substituent; Y is an oligo ether group) and a lithium salt represented by, for 2 to 15 wt% BaTiO ₃ is disclosed. By dispersing such a lithium salt in an appropriate structural material, an ion conductive material that is a solid electrolyte with high ionic conductivity can be obtained. Further, by mixing BaTiO ₃ , the strength of the ion conductive material can be increased. Both improvement and maintenance of good ionic conductivity can be achieved.

JP 2003-146951 A

Yuan Deng et al., “The preparation and conductivity properties of Li0.5La0.5TiO3 / inactive second phase composites”, Journal of Alloys and Compounds 472 (2009) 456-460 Hirotoshi Yamada et al., “Nano-structured Li-ionic conductive composite solid electrolyte synthesized by using mesoporous SiO2”, Solid State Ionics 176 (2005) 945-953

A solid electrolyte sintered body in which SiO ₂ is added to a Li ion conductive solid electrolyte can improve Li ion conductivity, but has a problem that the sintered density decreases. The present invention has been made in view of the above problems, and has as its main object to provide a solid electrolyte sintered body having an improved sintered density.

  In order to solve the above problems, the present invention includes a solid electrolyte material having Li ion conductivity and covalent bond and a crystalline material having ion bond, and the solid electrolyte material and the crystalline material. There is provided a solid electrolyte sintered body characterized by having no heterogeneous phase at the interface and having an average particle size of the crystalline material equal to or less than an average particle size of the solid electrolyte material.

  According to the present invention, there is no heterogeneous phase at the interface between the solid electrolyte material and the crystalline material, and the average particle size of the crystalline material is equal to or less than the average particle size of the solid electrolyte material, so that the solid that becomes the main phase Since the crystalline material which becomes a subphase can fill the grain boundary of the electrolyte material, a solid electrolyte sintered body with improved sintering density can be obtained.

  In the said invention, it is preferable that the weight ratio of the said solid electrolyte material and the said crystalline material is larger than 100: 0 and less than 100: 1.0. This is because the Li ion conductivity of the solid electrolyte sintered body can be improved.

  In the said invention, it is preferable that the weight ratio of the said solid electrolyte material and the said crystalline material exists in the range of 100: 0.1-100: 0.5. This is because the Li ion conductivity of the solid electrolyte sintered body can be further improved.

In the above invention, the crystalline material is preferably a BaTiO _3.

  In the said invention, it is preferable that the said solid electrolyte material is a phosphoric acid group containing Li ion conductor.

In the above invention, the phosphoric acid group-containing Li ion _{conductor, Li 1.5 Al 0.5 Ge 1.5 (} PO 4) is preferably _3.

  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 An all-solid-state lithium battery, wherein at least one of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer contains the above-described solid electrolyte sintered body. A lithium battery is provided.

  According to the present invention, an all-solid lithium battery having a high energy density can be obtained by using the above-described solid electrolyte sintered body.

  In this invention, there exists an effect that the solid electrolyte sintered compact with improved sintering density can be obtained.

It is explanatory drawing explaining an example of the solid electrolyte sintered compact of this invention. It is explanatory drawing explaining an example of the conventional solid electrolyte sintered compact. It is a schematic sectional drawing which shows an example of the all-solid-state lithium battery of this invention. 6 is a graph showing the results of XRD measurement of the solid electrolyte sintered body obtained in Example 3. 6 is a graph showing the results of XRD measurement of the solid electrolyte sintered body obtained in Comparative Example 4.

  Hereinafter, the solid electrolyte sintered body and the all solid lithium battery of the present invention will be described in detail.

A. Solid electrolyte sintered body First, the solid electrolyte sintered body of the present invention will be described. The solid electrolyte sintered body of the present invention contains a solid electrolyte material having Li ion conductivity and covalent bond, and a crystalline material having ion bondability, at the interface between the solid electrolyte material and the crystalline material. It has no heterogeneous phase, and the average particle size of the crystalline material is not more than the average particle size of the solid electrolyte material.

  FIG. 1 is an explanatory view illustrating an example of a solid electrolyte sintered body of the present invention. A solid electrolyte sintered body 10 in FIG. 1 contains a solid electrolyte material 1 having Li ion conductivity and covalent bonding, and a crystalline material 2 having ion bonding properties. The solid electrolyte sintered body 10 does not have a heterogeneous phase at the interface between the solid electrolyte material 1 and the crystalline material 2, and the average particle size of the crystalline material 2 is equal to or less than the average particle size of the solid electrolyte material 1. Yes.

  According to the present invention, there is no heterogeneous phase at the interface between the solid electrolyte material and the crystalline material, and the average particle size of the crystalline material is equal to or less than the average particle size of the solid electrolyte material, so that the solid that becomes the main phase Since the crystalline material which becomes a subphase can fill the grain boundary of the electrolyte material, a solid electrolyte sintered body with improved sintering density can be obtained. When the sintered density is high, the number of pores is reduced, and the energy density per volume of the solid electrolyte sintered body can be improved. Further, since the sintered density is high, the mechanical strength of the solid electrolyte sintered body can be improved.

Conventionally, it has been known that ion conductivity is improved by adding SiO ₂ as a subphase to a solid electrolyte material. However, as described above, there is a problem that the sintered density is lowered. The cause of this is not clear yet, but is thought to be as follows. That is, as illustrated in FIG. 2, in the solid electrolyte sintered body 10, the solid electrolyte material 1 reacts with SiO _2, and although not shown, a different phase is formed at the interface between the two, so that a crystal of SiO ₂ is formed. As a result, it is conceivable that the hardness of SiO ₂ is lowered and the shape cannot be maintained, for example, and adheres to the solid electrolyte material 1. As a result, it is presumed that SiO ₂ cannot fill the grain boundaries of the solid electrolyte material 1 and voids are generated. In addition, FIG. 2 is explanatory drawing explaining an example of the conventional solid electrolyte sintered compact.
On the other hand, in the present invention, as illustrated in FIG. 1, the solid electrolyte material 1 having Li ion conductivity and covalent bonding and the crystalline material 2 having ion bonding are used in combination. It is considered that the formation of a heterogeneous phase at the interface between the two can be suppressed because the reaction between the two is less likely to proceed due to the difference in binding properties. Since the crystalline material 2 is not disturbed in its crystallinity because it does not form a heterogeneous phase, it is presumed that the shape of the crystalline material 2 does not change due to a decrease in hardness, and that its particle size can be maintained. It is thought that it can enter. Thereby, it becomes possible to suppress that a void | hole produces in the grain boundary of the solid electrolyte material 1, and it is assumed that the sintered density of the solid electrolyte sintered compact 10 can be improved.

  The solid electrolyte sintered body of the present invention is a sintered body obtained by firing the solid electrolyte material and the crystalline material. In general, sintering refers to a phenomenon that solidifies and becomes dense when an aggregate of solid powders is heated. Further, the sintered body refers to an object that is solidified and dense by heating a solid powder aggregate. Whether or not it is a sintered body can be determined by whether or not the member has a density (filling rate) that cannot be achieved by the compacting process.

In addition, the solid electrolyte sintered body of the present invention is characterized in that there is no heterogeneous phase at the interface between the solid electrolyte material and the crystalline material. Here, the heterogeneous phase refers to a product derived from a decomposition product of a solid electrolyte material, a decomposition product of a crystalline material, a reaction product of a solid electrolyte material and a crystalline material, and the like. Further, “having no heterogeneous phase at the interface between the solid electrolyte material and the crystalline material” means that when analyzed by an X-ray diffraction (XRD) method, at the interface between the solid electrolyte material and the crystalline material, This means that no components other than the solid electrolyte material and the crystalline material are detected. Whether or not a heterogeneous phase is generated at the interface can be determined by, for example, X-ray diffraction measurement using RINT Ultimate III manufactured by Rigaku.
Hereinafter, the solid electrolyte sintered body of the present invention will be described for each configuration.

1. Solid electrolyte material The solid electrolyte material in this invention has a covalent bond. Here, “having a covalent bond” means an electronegativity of an element having the maximum electronegativity among elements other than the O element in the compound constituting the solid electrolyte material, and an electronegativity of the O element. The difference between and is 1.6 or less. Here, in the electronegativity of Pauling, considering that the electronegativity of the O element is 3.44, among the elements other than the O element in the compound, the electronegativity of the element having the maximum electronegativity The degree is 1.84 or more, preferably 1.9 or more, and more preferably 2.1 or more. This is because a stable covalent bond can be formed.

Moreover, the solid electrolyte material in this invention has Li ion conductivity. The solid electrolyte material before sintering preferably has high Li ion conductivity, and the Li ion conductivity at room temperature is preferably 1 × 10 ⁻⁶ S / cm or more, for example, 1 × 10 ⁻⁵ S. / Cm or more is more preferable.

The solid electrolyte material in the present invention is not particularly limited as long as it has Li ion conductivity and covalent bond properties. Among them, a phosphate group-containing Li ion conductor is preferable. This is because the phosphoric acid group-containing Li ion conductor is generally softer than other compounds, and as a result, the contact area with the active material is increased during the formation of an all-solid lithium battery, so that the interface resistance can be reduced. The phosphate group-containing Li ion conductor is usually a compound having an Li element and a phosphate group (PO ₄ skeleton). An example of the phosphate group-containing Li ion conductor is a compound having a NASICON type structure. Examples of the compound having a NASICON type structure include compounds represented by the general formula Li _{1 + x} Al _x Ge _2-x (PO ₄ ) ₃ (0 ≦ x ≦ 2). In the above general formula, the range of x may be 0 or more, more preferably greater than 0, and more preferably 0.3 or more. On the other hand, the range of x should just be 2 or less, and it is preferable that it is 1.7 or less especially, and it is more preferable that it is 1 or less. Above all, in the present invention, the phosphoric acid group-containing Li ion _{conductor, Li 1.5 Al 0.5 Ge 1.5 (} PO 4) is preferably _3. In this case, among the elements other than the O element in the compound, the element having the highest electronegativity is the P element, and the electronegativity of the P element is 2.19. The difference from the negative degree is 1.25.

Another example of the compound having a NASICON structure is a compound represented by the general formula Li _{1 + x} Al _x Ti _2-x (PO ₄ ) ₃ (0 ≦ x ≦ 2). In the above general formula, the range of x may be 0 or more, more preferably greater than 0, and more preferably 0.3 or more. On the other hand, the range of x should just be 2 or less, and it is preferable that it is 1.7 or less especially, and it is more preferable that it is 1 or less. Above all, in the present invention, the phosphoric acid group-containing Li ion _{conductor, Li 1.5 Al 0.5 Ti 1.5 (} PO 4) is preferably _3. Other examples of the phosphoric acid group-containing Li ion conductor, may be mentioned _Li 3 PO ₄ and the like. In addition, as the solid electrolyte material in the present invention, for example, a sulfide solid electrolyte material such as Li ₇ P ₃ S ₁₁ (the electronegativity of S element is 2.58) can be used.

  The solid electrolyte material may be amorphous (glass), may have crystallinity, or may be crystalline. Here, “amorphous” means a state where a predetermined crystal peak is not detected by X-ray diffraction measurement, and “having crystallinity” means a state where a predetermined crystal peak is detected by X-ray diffraction measurement “Crystalline” means a state of heat treatment at a temperature higher than the crystallization temperature. The state of the solid electrolyte material in the solid electrolyte sintered body can be determined by, for example, X-ray diffraction measurement using RINT Ultimate III manufactured by Rigaku.

In addition, the shape of the solid electrolyte material before sintering is, for example, powdery, and the average particle diameter is not particularly limited as long as it is equal to or larger than the average particle diameter of the crystalline material described later. The thickness is preferably in the range of 100 nm to 5 μm, and more preferably in the range of 500 nm to 4 μm. If the average particle size is too large, it may be difficult to obtain a dense solid electrolyte sintered body. If the average particle size is too small, it may be difficult to produce a solid electrolyte material. Because there is sex. Incidentally, the average particle diameter can be defined by the D ₅₀ as measured by a particle size distribution meter. Moreover, it can define similarly about the average particle diameter of each material mentioned later.

2. Crystalline material The crystalline material in the present invention has ion binding properties. Here, “crystalline material” refers to a material that has been heat-treated at a temperature equal to or higher than the crystallization temperature. Further, “having ionic bonding” means that, among elements other than the O element in the compound constituting the crystalline material, the electronegativity of the element having the maximum electronegativity, the electronegativity of the O element, This means that the difference is 1.7 or more. Here, in the electronegativity of Pauling, considering that the electronegativity of the O element is 3.44, among the elements other than the O element in the compound, the electronegativity of the element having the maximum electronegativity The degree is 1.70 or less, preferably 1.65 or less, and more preferably 1.60 or less. This is because a stable ionic bond can be formed.

The crystalline material in the present invention is not particularly limited as long as it has ionic bonding properties, and examples thereof include BaTiO ₃ , TiO ₂ , Al ₂ O ₃ , and MgO. Among these, in the present invention, the crystalline material is preferably BaTiO ₃ . In this case, among the elements other than the O element in the compound, the element having the highest electronegativity is the Ti element, and the electronegativity of the Ti element is 1.54. The difference from the negative degree is 1.90.

  The shape of the crystalline material before sintering is, for example, powdery, and the average particle size is not particularly limited as long as it is equal to or less than the average particle size of the above-described solid electrolyte material. It is preferably in the range of 200 nm, and more preferably in the range of 20 nm to 100 nm. If the average particle size is too large, it may be difficult to obtain a dense solid electrolyte sintered body. If the average particle size is too small, it may be difficult to produce a crystalline material. Because there is sex.

3. Solid electrolyte sintered body The weight ratio of the solid electrolyte material and the crystalline material in the solid electrolyte sintered body of the present invention is preferably greater than 100: 0 and less than 100: 1.0, and 100: 0. More preferably, it is in the range of 1 to 100: 0.5. This is because the Li ion conductivity of the solid electrolyte sintered body can be improved.

  In addition, the sintered density of the solid electrolyte sintered body of the present invention varies depending on the types of the solid electrolyte material and the crystalline material, but does not contain the crystalline material and contains only the solid electrolyte material. What is necessary is just to be higher than the sintered density of the sintered compact.

  The solid electrolyte sintered body of the present invention may be in a pellet form or a sheet form. As the shape of the solid electrolyte sintered body, the same shape as that of various existing sintered bodies can be used. Examples thereof include a columnar shape, a flat plate shape, and a cylindrical shape. Furthermore, the solid electrolyte sintered body may be, for example, a powder obtained by pulverizing a pellet-shaped solid electrolyte sintered body. Especially, it is preferable that a solid electrolyte sintered compact is a pellet form. This is because a solid electrolyte sintered body having high strength and strong impact resistance can be obtained.

The solid electrolyte sintered body of the present invention preferably has high Li ion conductivity, and the Li ion conductivity at room temperature is preferably 1 × 10 ⁻⁶ S / cm or more, for example, 1 × 10 ^−5. More preferably, it is S / cm or more.

  The solid electrolyte sintered body of the present invention can be used for any application that requires Li ion conductivity. Examples of such applications include batteries and sensors. Especially, it is preferable that the said solid electrolyte sintered compact is what is used for a battery. Furthermore, when using the said solid electrolyte sintered compact for a battery, you may use for a positive electrode active material layer, may be used for a negative electrode active material layer, and may be used for a solid electrolyte layer.

B. Next, the all solid lithium battery of the present invention will be described. The all solid lithium battery of the present invention is formed between 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 the positive electrode active material layer and the negative electrode active material layer. An all-solid lithium battery having a solid electrolyte layer, wherein at least one of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer contains the solid electrolyte sintered body described above. Is.

  FIG. 3 is a schematic cross-sectional view showing an example of the all solid lithium battery of the present invention. 3 includes a positive electrode active material layer 11 containing a positive electrode active material, a negative electrode active material layer 12 containing a negative electrode active material, and between the positive electrode active material layer 11 and the negative electrode active material layer 12. The formed solid electrolyte layer 13, the positive electrode current collector 14 that collects current from the positive electrode active material layer 11, the negative electrode current collector 15 that collects current from the negative electrode active material layer 12, and a battery that houses these members And a case 16. In the present invention, at least one of the positive electrode active material layer 11, the negative electrode active material layer 12, and the solid electrolyte layer 13 is a solid electrolyte sintered body (for example, a powdery material) described in the above “A. Solid electrolyte sintered body”. It is characterized by containing a solid electrolyte sintered body).

According to the present invention, an all-solid lithium battery having a high energy density can be obtained by using the above-described solid electrolyte sintered body.
Hereinafter, the all-solid lithium battery of the present invention will be described for each configuration.

1. First, 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 further contain at least one of a solid electrolyte material, a conductive material and a binder as necessary.

  In the present invention, the solid electrolyte material contained in the positive electrode active material layer is the solid electrolyte sintered body (for example, a powdered solid electrolyte sintered body) described in the above “A. Solid electrolyte sintered body”. Is preferred. This is because an all-solid lithium battery having a high energy density can be obtained. The content of the solid electrolyte material in the positive electrode active material layer is, for example, in the range of 0.1% by volume to 80% by volume, especially in the range of 1% by volume to 60% by volume, in particular, 10% by volume to 50% by volume. It is preferable to be within the range.

As the positive electrode active material, is not particularly limited, for _{example, LiCoO 2, LiMnO 2, LiNiO} 2, LiVO 2, LiNi 1/3 Co 1/3 Mn 1/3 rock salt layered type active material such as _{O 2} And spinel type active materials such as LiMn ₂ O ₄ and Li (Ni _0.5 Mn _1.5 ) O ₄ , and olivine type active materials such as LiFePO ₄ and LiMnPO ₄ . Si-containing oxides such as Li ₂ FeSiO ₄ and Li ₂ MnSiO ₄ may be used as the positive electrode active material.

  Examples of the shape of the positive electrode active material include a particle shape, and among them, a true spherical shape or an elliptical spherical shape is preferable. Moreover, when a positive electrode active material is a particle shape, it is preferable that the average particle diameter exists in the range of 0.1 micrometer-50 micrometers, for example. Further, the content of the positive electrode active material in the positive electrode active material layer is, for example, preferably in the range of 10% by volume to 99% by volume, and more preferably in the range of 20% by volume to 99% by volume.

  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 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. Moreover, as a formation method of a positive electrode active material layer, the method etc. which compression-mold the material which comprises a positive electrode active material layer can be mentioned, for example.

2. 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 further contain at least one of a solid electrolyte material, a conductive material, and a binder as necessary.

  In the present invention, the solid electrolyte material contained in the negative electrode active material layer is the solid electrolyte sintered body (for example, powdered solid electrolyte sintered body) described in the above-mentioned “A. Solid electrolyte sintered body”. Is preferred. This is because an all-solid lithium battery having a high energy density can be obtained. The content of the solid electrolyte material in the negative electrode active material layer is, for example, in the range of 0.1% by volume to 80% by volume, especially in the range of 1% by volume to 60% by volume, in particular, 10% by volume to 50% by volume. It is preferable to be within the range.

  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. Further, the content of the negative electrode active material in the negative electrode active material layer is, for example, preferably in the range of 10% by volume to 99% by volume, and more preferably in the range of 20% by volume to 99% by volume. Note that the conductive material and the binder used in the negative electrode active material layer are the same as those in the positive electrode active material layer described above.

  The thickness of the negative electrode active material layer is preferably in the range of 0.1 μm to 1000 μm, for example. Moreover, as a formation method of a negative electrode active material layer, the method etc. which compression-mold the material which comprises a negative electrode active material layer can be mentioned, for example.

3. Next, the solid electrolyte layer in the present invention will be described. The solid electrolyte layer in the present invention is a layer formed between the positive electrode active material layer and the negative electrode active material layer, and is a layer composed of a solid electrolyte material. The solid electrolyte material contained in the solid electrolyte layer is not particularly limited as long as it has Li ion conductivity.

  In the present invention, the solid electrolyte material contained in the solid electrolyte layer is the solid electrolyte sintered body (for example, pellet-like, powdered solid electrolyte sintered body) described in the above “A. Solid electrolyte sintered body”. Preferably there is. This is because an all-solid lithium battery having a high energy density can be obtained. The content of the solid electrolyte material in the solid electrolyte layer is not particularly limited as long as a desired insulating property can be obtained. For example, the content is in the range of 10% by volume to 100% by volume, especially 50% by volume. It is preferable to be within a range of ˜100 volume%. In particular, in the present invention, the solid electrolyte layer is preferably composed only of the solid electrolyte sintered body. This is because an all-solid lithium battery having a higher energy density can be obtained.

  In addition, about the binder used for a solid electrolyte layer, it is the same as that of the case in the positive electrode active material layer mentioned above. The thickness of the solid electrolyte layer is, for example, preferably in the range of 0.1 μm to 1000 μm, and more preferably in the range of 0.1 μm to 300 μm. Moreover, as a formation method of a solid electrolyte layer, the method of compression-molding the material which comprises a solid electrolyte layer, etc. can be mentioned, for example.

4). Other Configurations The all solid lithium battery of the present invention has at least the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte 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. Among them, SUS is preferable. In addition, the thickness and shape of the positive electrode current collector and the negative electrode current collector are preferably selected as appropriate according to the application of the all solid lithium battery. Moreover, the battery case of a general all solid lithium battery can be used for the battery case used for this invention. Examples of the battery case include a SUS battery case.

5. All-solid lithium battery The all-solid lithium battery of the present invention may be a primary battery or a secondary battery, and among these, a secondary battery is preferable. This is because it can be repeatedly charged and discharged and is useful, for example, as a vehicle-mounted battery. Examples of the shape of the all solid 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 all-solid-state lithium battery of this invention will not be specifically limited if it is a method which can obtain the all-solid-state lithium battery mentioned above, It is the same as the manufacturing method of a general all-solid-state lithium battery. The method can be used. As an example of an all-solid-state lithium battery manufacturing method, a power generation element is manufactured by sequentially pressing a material constituting a positive electrode active material layer, a material constituting a solid electrolyte layer, and a material constituting a negative electrode active material layer. A method of housing the power generation element inside the battery case and caulking the battery case can be exemplified.

  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.

  The present invention will be described more specifically with reference to the following examples.

[Example 1]
First, glassy Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ (manufactured by Hosokawa Micron Corporation, average particle size 100 nm, LAGP) and BaTiO ₃ (manufactured by Kyoritsu Materials Co., Ltd., average particle size 50 nm) Were weighed so as to have a weight ratio of LAGP: BaTiO ₃ = 100: 0.1, and mixed for 20 minutes using an agate mortar. Next, 0.3 g of the obtained mixture was uniaxially pressed at a pressure of 5 MPa using a pellet die having a diameter of 13 mm to produce a green compact. Furthermore, the obtained green compact was hydrostatically pressed (CIP) at a pressure of 196 MPa to produce pellets. Subsequently, the obtained pellets were fired under conditions of an air atmosphere and 650 ° C. for 2 hours to obtain a solid electrolyte sintered body.

[Example 2]
A solid electrolyte sintered body was obtained in the same manner as in Example 1 except that the weight ratio of LAGP and BaTiO ₃ was changed to LAGP: BaTiO ₃ = 100: 0.5.

[Example 3]
A solid electrolyte sintered body was obtained in the same manner as in Example 1 except that the weight ratio of LAGP and BaTiO ₃ was changed to LAGP: BaTiO ₃ = 100: 1.0.

[Comparative Example 1]
A solid electrolyte sintered body was obtained in the same manner as in Example 1 except that BaTiO ₃ was not used.

[Comparative Example 2]
A solid electrolyte sintered body was obtained in the same manner as in Example 1 except that BaTiO ₃ was changed to SiO ₂ (manufactured by Admatechs, average particle size 50 nm).

[Comparative Example 3]
A solid electrolyte sintered body was obtained in the same manner as in Comparative Example 2 except that the weight ratio of LAGP and SiO ₂ was changed to LAGP: SiO ₂ = 100: 0.5.

[Comparative Example 4]
A solid electrolyte sintered body was obtained in the same manner as in Comparative Example 2 except that the weight ratio of LAGP and SiO ₂ was changed to LAGP: SiO ₂ = 100: 1.0.

[Evaluation]
(X-ray diffraction measurement)
The solid electrolyte sintered bodies obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were pulverized in an agate mortar, and X-ray diffraction (XRD) measurement was performed. For XRD measurement, RIG Ultimate III made by Rigaku was used, and CuKα rays were used. The results of XRD measurement of the solid electrolyte sintered bodies obtained in Example 3 and Comparative Example 4 are shown in FIGS. 4 and 5, respectively. As shown in FIG. 4, in the solid electrolyte sintered body obtained in Example 3, the crystal peak of LAGP was observed, and the crystal peak not attributed to LAGP and BaTiO ₃ was not observed. Therefore, it was confirmed that no heterogeneous phase was generated at the interface between LAGP and BaTiO ₃ . Although not shown, it was confirmed that no heterogeneous phase was generated in the solid electrolyte sintered bodies obtained in Examples 1 and 2. On the other hand, as shown in FIG. 5, in the solid electrolyte sintered body obtained in Comparative Example 4, a crystal peak was confirmed in the vicinity of 2θ = 19 °, and this was observed in LAGP and SiO ₂ . Is an unassigned crystal peak, and it was confirmed that a heterogeneous phase occurred at the interface between LAGP and SiO ₂ . Although not shown, it was confirmed that the solid electrolyte sintered bodies obtained in Comparative Examples 2 and 3 were also different in phase. Although not shown, in the solid electrolyte sintered body obtained in Comparative Example 1, a crystal peak of LAGP was observed.

(Sintering density measurement)
The sintered density of the solid electrolyte sintered bodies obtained in Examples 1 to 3 and Comparative Examples 1 to 4 was measured. The sintered density was measured as follows. The sintered density was calculated by measuring the size and weight of the solid electrolyte sintered body. The results are shown in Tables 1 and 2. As shown in Table 1, it was confirmed that in the solid electrolyte sintered bodies obtained in Examples 1 to 3, the sintered density was higher than that of the solid electrolyte sintered body obtained in Comparative Example 1. In contrast, as shown in Table 2, the sintered density of the solid electrolyte sintered bodies obtained in Comparative Examples 2 to 4 is lower than that of the solid electrolyte sintered body obtained in Comparative Example 1. Was confirmed.

(Li ion conductivity measurement)
For the solid electrolyte sintered bodies obtained in Examples 1 to 3 and Comparative Examples 1 to 4, Li ion conductivity (normal temperature) was measured by an AC impedance method. The measurement of Li ion conductivity was performed as follows. Impedance was measured by sputtering gold on both surfaces of the solid electrolyte sintered body. Solartron 1260 was used for measurement, and the measurement conditions were an applied voltage of 5 mV and a measurement frequency range of 0.01 MHz to 1 MHz. The results are shown in Tables 1 and 2. As shown in Table 1, the solid electrolyte sintered bodies obtained in Examples 1 and 2 have higher Li ion conductivity than the solid electrolyte sintered body obtained in Comparative Example 1, It was confirmed that both the density and Li ion conductivity were improved. In addition, it was confirmed that the solid electrolyte sintered compact obtained in Example 3 shows lower Li ion conductivity than the solid electrolyte sintered compact obtained in Comparative Example 1. This is presumably because the content of BaTiO ₃ that is an insulator is too large. On the other hand, as shown in Table 2, the solid electrolyte sintered bodies obtained in Comparative Examples 2 to 4 have a slightly higher Li ion conductivity than the solid electrolyte sintered body obtained in Comparative Example 1. confirmed.

DESCRIPTION OF SYMBOLS 1 ... Solid electrolyte material 2 ... Crystalline material 10 ... Solid electrolyte sintered body 11 ... Positive electrode active material layer 12 ... Negative electrode active material layer 13 ... Solid electrolyte layer 14 ... Positive electrode collector 15 ... Negative electrode collector 16 ... Battery case 20 ... All solid lithium battery

Claims (7)

A solid electrolyte material having Li ion conductivity and covalent bond, and a crystalline material having ion bond,
There is no heterogeneous phase at the interface between the solid electrolyte material and the crystalline material,
The solid electrolyte sintered body, wherein an average particle diameter of the crystalline material is equal to or less than an average particle diameter of the solid electrolyte material.   2. The solid electrolyte sintered body according to claim 1, wherein a weight ratio of the solid electrolyte material and the crystalline material is greater than 100: 0 and less than 100: 1.0.   The solid electrolyte sintered body according to claim 2, wherein a weight ratio of the solid electrolyte material and the crystalline material is in a range of 100: 0.1 to 100: 0.5. The solid electrolyte sintered body according to any one of claims 1 to ₃ , wherein the crystalline material is BaTiO ₃ .   The solid electrolyte sintered body according to any one of claims 1 to 4, wherein the solid electrolyte material is a phosphate group-containing Li ion conductor. The solid electrolyte sintered body according to claim 5, wherein the phosphoric acid group-containing Li ion conductor is Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ . All solid lithium having 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 A battery,
At least one of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer contains the solid electrolyte sintered body according to any one of claims 1 to 6. All solid lithium battery.

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