Garnet-type lithium solid electrolyte material and battery

Description

[Technical Field]

[0001] The present invention relates to a garnet-type lithium solid electrolyte material and a battery. [Background technology]

[0002] Lithium-ion batteries have traditionally been used in smartphone batteries, electric vehicle batteries, and other applications. Conventional lithium-ion batteries use a liquid electrolyte as an electrolyte through which Li (lithium) ions can move. However, it has become difficult to achieve higher capacity, higher voltage, higher energy density, and faster charging performance with liquid electrolyte-based lithium-ion batteries. Therefore, development of all-solid-state batteries, which use a solid electrolyte instead of a liquid electrolyte, is underway to meet these various requirements. Examples of solid electrolytes used in all-solid-state lithium-ion batteries include sulfide-based and oxide-based lithium-ion crystals.

[0003] Sulfide-based solid electrolytes have high Li-ion conductivity and are suitable for batteries that prioritize energy density. However, there is an issue that if the crystalline structure of the solid electrolyte is destroyed by high temperatures, a toxic substance (hydrogen sulfide (H2S)) is released. Therefore, development of oxide-based solid electrolytes is underway for applications that do not release toxic substances and require greater safety and stability.

[0004] On the other hand, oxide-based solid electrolytes have the problem of lower Li-ion conductivity compared to sulfide-based solid electrolytes. To apply them to bulk-type all-solid-state batteries, the conductivity at room temperature must be 10 -3 An oxide-based solid electrolyte with a resistance of 10 (S / cm) or higher is desirable. -3 As an oxide-based solid electrolyte with a conductivity of about 1000 kJ / cm, for example, perovskite-type La 0.51 Li 0.34 TiO 2.94 Garnet-type lithium solid electrolyte materials such as those listed above are known (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Chemistry, July 1, 2012, Internet<URL: http: / / www2.chem.osakafu-u.ac.jp / ohka / ohka2 / research / battery_li.pdf> Summary of the Invention [Problem to be solved by the invention]

[0006] Among the solid electrolytes using lithium-containing oxides that have been proposed to date, sintered bodies of garnet-type lithium solid electrolytes prepared by sintering methods are well known. However, sintered bodies tend to contain voids and have a rough surface, making it difficult to densify the resulting sintered bodies. Furthermore, sintered garnet-type lithium solid electrolytes have problems with low mechanical strength due to the voids and rough surface, making them prone to breakage during processing and handling. Furthermore, because a thickness is required to ensure mechanical strength, it is difficult to make them thin.

[0007] Furthermore, because sintered garnet-type lithium solid electrolytes have grain boundaries, the interfacial resistance when lithium ions pass through the grain boundaries is large, making it difficult to improve lithium ion conductivity. There is also the problem of internal short circuits occurring in the crystals.

[0008] The present invention has been made in view of the above-mentioned problems, and aims to provide a garnet-type lithium solid electrolyte material that can improve lithium ion conductivity and increase internal short-circuit critical current density, and also to provide a battery that includes at least a part of the garnet-type lithium solid electrolyte material. [Means for solving the problem]

[0009] In order to solve the above problems, the garnet-type lithium solid electrolyte material of the present invention is characterized by being made of a single crystal and having a surface roughness Ra of the front and back surfaces in the range of 0.1 nm to 10 nm.

[0010] In the garnet-type lithium solid electrolyte material of the present invention, since no crystal grain boundaries exist inside, it is possible to improve the lithium ion conductivity and increase the internal short-circuit critical current density.

[0011] In one embodiment of the present invention, the three-point bending strength is in the range of 47.5 MPa or more and 155.5 MPa or less.

[0012] In one aspect of the present invention, the single crystal is a free-standing crystal having a thickness.

[0013] In one aspect of the present invention, the thickness is in the range of 20 μm to 1 mm.

[0014] In one aspect of the present invention, the thickness is in the range of 30 μm to 0.5 mm.

[0015] In one embodiment of the present invention, the planar shape is circular or circular with an orientation flat surface formed thereon, and the diameter is 30 mm or more.

[0016] In one embodiment of the present invention, the planar shape is rectangular, and the area of ​​the rectangle is 730 mm 2 That's all.

[0017] In order to solve the above problems, the battery of the present invention is characterized by using at least a part of any one of the garnet-type lithium solid electrolyte materials described above. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a garnet-type lithium solid electrolyte material that can improve lithium ion conductivity and increase internal short-circuit critical current density, and also to provide a battery that includes at least a part of the garnet-type lithium solid electrolyte material. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is an explanatory diagram showing the structure of a battery 10 using a garnet-type lithium solid electrolyte material 1 according to an embodiment of the present invention. [Figure 2] 1 is a process diagram schematically showing a processing step for the garnet-type lithium solid electrolyte material 1 according to the present embodiment. [Figure 3] 1 is a photograph showing an example of a sample for measuring the three-point bending strength of a garnet-type lithium solid electrolyte material. [Figure 4] FIG. 1 is a schematic diagram showing a method for measuring the three-point bending strength of a garnet-type lithium solid electrolyte material. [Figure 5] 1 is a table showing the measurement results of three-point bending strength and maximum load in Example 1. [Figure 6] 1 is a graph showing the relationship between the surface roughness and three-point bending strength of a garnet-type lithium solid electrolyte material. In the figure, dots plotted represent the measurement results for sintered bodies, and crosses plotted represent the values ​​for single crystals. [Figure 7] 1 is a table showing the relationship between the surface roughness of a garnet-type lithium solid electrolyte material and the lithium ion conductivity and the internal short circuit critical current density. DETAILED DESCRIPTION OF THE INVENTION

[0020] The first feature of this embodiment is that the garnet-type lithium solid electrolyte material is made of a single crystal, and the surface roughness Ra of the front and back surfaces is in the range of 0.1 nm to 10 nm.

[0021] This structure reduces interfacial resistance due to grain boundaries, improving lithium ion conductivity and preventing internal short circuits. Furthermore, the surface roughness of 0.1 nm or more simplifies the surface processing process.

[0022] The second feature is that the three-point bending strength is in the range of 47.5 MPa or more and 155.5 MPa or less.

[0023] This configuration can prevent damage to the garnet-type lithium solid electrolyte material during processing and handling.

[0024] The third feature is that the single crystal is a single, self-supporting crystal having a certain thickness.

[0025] According to this configuration, the garnet-type lithium solid electrolyte material maintains its bulk shape, which facilitates mechanical handling and processing.

[0026] The fourth feature is that the thickness is in the range of 20 μm to 1 mm.

[0027] According to this configuration, the garnet-type lithium solid electrolyte material can be used for a battery by forming electrodes on the front and back surfaces thereof, and handling and processing are also easy.

[0028] The fifth feature is that the thickness is in the range of 30 μm to 0.5 mm.

[0029] According to this configuration, the garnet-type lithium solid electrolyte material can be used for batteries by forming electrodes on the front and back surfaces thereof, and furthermore, mechanical strength can be ensured, breakage can be suppressed, and resistance can be reduced.

[0030] The sixth feature is that the planar shape is circular or circular with an orientation flat surface formed thereon, and the diameter is 30 mm or more.

[0031] According to this configuration, when the garnet-type lithium solid electrolyte material is enlarged and used in a battery, it becomes possible to increase the capacity and output of the all-solid-state battery.

[0032] The seventh feature is that the plane shape is square, and the area of ​​the square is 730 mm 2 That's all.

[0033] According to this configuration, when the garnet-type lithium solid electrolyte material is enlarged and used in a battery, it becomes possible to increase the capacity and output of the all-solid-state battery.

[0034] An eighth feature is a battery using at least a part of any one of the garnet-type lithium solid electrolyte materials described above.

[0035] According to this configuration, by using a garnet-type lithium solid electrolyte material, a battery with high lithium ion conductivity and large internal short-circuit critical current density can be obtained, and a high-power all-solid-state battery can be realized.

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be designated by the same reference numerals, and redundant descriptions will be omitted where appropriate.

[0037] The garnet-type lithium solid electrolyte material of this embodiment has a cubic garnet-type structure and contains at least four metal atoms, three of which are Li, La, and Zr, and the other metal atom is any of Nb, Ta, and Ga. Examples of garnet-type lithium solid electrolyte materials include those having the general formula Li 7-x-y La3Zr 2-x-y Nb x Ta y O 12 (0.2≦x+y≦1.0, 0≦x≦1.0, 0≦y≦1.0), or Li 7-3x Ga x La3Zr2O 12 (0.08≦x≦0.5).

[0038] In this embodiment, the term "single crystal" means that the crystal plane orientation of the garnet-type lithium solid electrolyte material is uniform, and this can be confirmed by, for example, the observation of clear peaks due to the (400) and (800) plane orientations in the results of an X-ray diffraction spectrum measurement using CuKα radiation. The single crystal nature of the garnet-type lithium solid electrolyte material means that there are no grain boundaries, which allows for reduced interface resistance, improved internal short-circuit critical current density, and high bending strength.

[0039] In this embodiment, the term "self-supporting garnet-type lithium solid electrolyte material" means that the bulk garnet-type lithium solid electrolyte material maintains its shape even without being supported by other members. Therefore, even if it is a single crystal, a thin film or a laminated structure epitaxially grown on another substrate is not included in the term "self-supporting." Furthermore, the self-supporting garnet-type lithium solid electrolyte material can be held and moved by a processing device or a jig.

[0040] In this embodiment, the three-point bending strength of the garnet-type lithium solid electrolyte material is preferably measured by a method conforming to JIS standard R 1601. However, if the size of the obtained garnet-type lithium solid electrolyte material does not satisfy the size required by the above standard, the size in the above standard may be changed and the measurement may be performed and converted.

[0041] 1 is an explanatory diagram showing the structure of a battery 10 using a garnet-type lithium solid electrolyte material 1 according to this embodiment. As shown in FIG. 1, the battery 10 includes the garnet-type lithium solid electrolyte material 1, a positive electrode 2, and a negative electrode 3.

[0042] The garnet-type lithium solid electrolyte material 1 has a cubic garnet-type structure and contains Li 7-x-y La3Zr 2-x-y Nb x Ta y O 12 (0.2≦x+y≦1.0, 0≦x≦1.0, 0≦y≦1.0), or Li 7-3x Ga xLa3Zr2O 12 The garnet-type lithium solid electrolyte material 1 is composed of a free-standing single crystal with a lattice constant of 0.08≦x≦0.5. While FIG. 1 shows a flat plate-shaped garnet-type lithium solid electrolyte material 1, the shape is not limited thereto and may be a rectangular parallelepiped, prism, cylinder, polygonal pyramid, cone, polygonal truncated pyramid, truncated cone, or the like. The garnet-type lithium solid electrolyte material 1 has a front surface and a back surface, with a positive electrode 2 formed on the front surface and a negative electrode 3 formed on the back surface. Furthermore, although not shown, a film or foil such as a current collector made of Al or Au is provided on the outside of each of the positive electrode 2 and the negative electrode 3.

[0043] As described below, the garnet-type lithium solid electrolyte material 1 preferably has a surface roughness Ra of 0.1 nm or more and 10 nm or less on the front and back surfaces. By making the garnet-type lithium solid electrolyte material 1 a single crystal with a surface roughness Ra of 0.1 nm or more and 10 nm or less, the interfacial resistance can be reduced, improving lithium ion conductivity, and internal short circuits can be reduced, simplifying the surface processing step. Furthermore, as described below, the garnet-type lithium solid electrolyte material 1 preferably has a three-point bending strength of 47.5 MPa or more and 155.5 MPa or less. Having the garnet-type lithium solid electrolyte material 1 have a three-point bending strength in this range can reduce breakage during processing and handling.

[0044] The thickness of the garnet-type lithium solid electrolyte material 1 is preferably in the range of 20 μm to 1 mm. When the thickness is in this range, the garnet-type lithium solid electrolyte material 1 can be used for batteries by forming a positive electrode 2 and a negative electrode 3 on the front and back surfaces thereof, and handling and processing are also easy. A more preferred thickness is in the range of 30 μm to 0.5 mm. By setting the thickness in this range, mechanical strength can be further ensured, breakage can be suppressed, and the resistance value can be reduced.

[0045] The size of the garnet-type lithium solid electrolyte material 1 is preferably a diameter of 30 mm or more when the planar shape is circular or a circular shape with an orientation flat formed thereon. When the planar shape is rectangular, the area is preferably 730 mm or more. 2 This makes it possible to increase the capacity and output of the all-solid-state battery by increasing the size of the garnet-type lithium solid electrolyte material 1 and using it in the battery 10.

[0046] The positive electrode 2 is an electrode film formed on the surface of the garnet-type lithium solid electrolyte material 1, and is, for example, LiNi 0.8 Co 0.15 Al 0.05 O2(NCA), etc. can be used. The negative electrode 3 is an electrode film formed on the back surface of the garnet-type lithium solid electrolyte material 1, and can be made of, for example, Li, etc. The positive electrode 2 and the negative electrode 3 can be formed by known methods such as compression bonding and sintering.

[0047] Next, a method for producing the garnet-type lithium solid electrolyte material of this embodiment will be described. First, in a raw material preparation step, various raw materials for the garnet-type lithium solid electrolyte material are prepared, pulverized, and mixed in a predetermined ratio to process the raw materials into a powder. There are no limitations on the pulverization and mixing methods, and known methods can be used. Thereafter, in a molding step, the powdered raw materials are pressure-molded and sintered to obtain a raw material sintered body. There are no limitations on the pressure-molding and sintering methods, and known methods can be used.

[0048] As raw materials for the garnet-type lithium solid electrolyte material, lithium compounds, lanthanum compounds, zirconium compounds, tantalum compounds, and niobium compounds can be used. Examples of lithium compounds include Li2O and Li2CO3. Examples of lanthanum compounds include La2O3 and La(OH)3. Examples of zirconium compounds include ZrO2 and ZrC l4, La2Zr2O7, Li2ZrO3, etc. Tantalum compounds include, for example, Ta2O5 and TaCl5, etc. Niobium compounds include, for example, Nb2O5, LiNbO3, LaNbO4, etc.

[0049] Next, in the molten portion forming step, at least a portion of the raw material sintered body is melted to form a molten portion, and in the growth step, the molten portion is cooled to grow a garnet-type lithium solid electrolyte material. The methods for the molten portion forming step and the growth step are not limited, and crystal growth can be achieved using various known melting methods, such as the FZ (Floating Zone) method, the Bridgman method, the Kyropolous method, the TSSG (Top Seeded Solution Growth) method, the LPE (Liquid Phase Epitaxy) method, the CZ (Czochralski) method, and the EFG (Edge-defined Film-fed Growth) method. To achieve a larger garnet-type lithium solid electrolyte material, the CZ method or the EFG method is preferred. In the growth method using a crucible, Ir, which does not react with the raw material melt, is preferably used as the crucible material. The atmosphere used in the growth step is preferably N2, Ar, or dry air.

[0050] Next, a method for processing the single crystal of the garnet-type lithium solid electrolyte material obtained in the growth step will be described. FIG. 2 is a process diagram schematically illustrating the processing step of the garnet-type lithium solid electrolyte material 1 according to this embodiment. As shown in FIG. 2(a), an as-grown single crystal ingot is grown and formed in the growth step. Next, as shown in FIG. 2(b), the outer diameter of the as-grown single crystal ingot after the growth step is ground to process the single crystal garnet-type lithium solid electrolyte material into an approximately cylindrical shape. Next, as shown in FIG. 2(c), the approximately cylindrical single crystal is sliced ​​into a plate shape. A known diamond slicer or wire saw device can be used for slicing. Next, as shown in FIG. 2(d), the outer periphery of the front surface of the plate-shaped single crystal is chamfered. Finally, as shown in FIG. 2(e), the front and back surfaces are ground and polished to obtain the single crystal garnet-type lithium solid electrolyte material 1.

[0051] When grinding and polishing garnet-type lithium solid electrolyte materials, water or oil can be used as the solvent, and an abrasive containing dispersed diamond particles, alumina particles, SiC particles, or the like can be used. Cast iron, copper, nonwoven fabric, or the like can be used as the polishing plate. When polishing garnet-type lithium solid electrolyte materials, the surface roughness Ra of the front and back surfaces can be adjusted to a range of 0.1 nm to 10 nm by reducing the particle size of the abrasive particles contained in the abrasive. The method for measuring the surface roughness Ra is not limited, and measurements using a laser microscope or an atomic force microscope (AFM) can be used.

[0052] FIG. 3 is a photograph showing an example of a sample for measuring the three-point bending strength of a garnet-type lithium solid electrolyte material. The sample shown in FIG. 3 is Example 1 in this embodiment, and was cut to a width of 4 mm (dimension A in FIG. 3) from a single crystal of garnet-type lithium solid electrolyte material 1 having a diameter of 7 mm (horizontal direction in FIG. 3) and a thickness of 0.63 mm. The length of the linear portion cut out to a width of 4 mm was approximately 6 mm. In addition, the front, back, and both end faces were polished using abrasive grains with a particle size of 0.5 μm or less, and the outer periphery on the front side was chamfered. In addition, a sintered body of the garnet-type lithium solid electrolyte material was processed into the same shape as the above-mentioned Example to prepare Comparative Example 1.

[0053] <Measurement of three-point bending strength> The three-point bending strength of a sample of the garnet-type lithium solid electrolyte material processed into the shape shown in Figure 3 was measured using an EZ-Test manufactured by Shimadzu Corporation. The three-point bending strength is preferably measured in accordance with JIS R1601, which is a room-temperature bending strength test method for fine ceramics. JIS R1601 requires the sample shape to be 4 mm wide, 3 mm thick, and 36 mm long or longer, with chamfering, sample quantity N≧10, support distance 30 mm or 40 mm, support tip radius 2 to 3 mm, and crosshead speed 0.5 mm / min.

[0054] However, the obtained single crystal of the garnet-type lithium solid electrolyte material 1 was significantly smaller than the support distance specified in JIS R1601, and the standard could not be used as is. Therefore, the support distance was set to 4 mm, and the tip shape radius of the support was changed to 1 mm at both ends and 1.5 mm at the center, and three-point bending strength measurements were performed for Example 1 and Comparative Example 1.

[0055] 4 is a schematic diagram showing a method for measuring the three-point bending strength of a garnet-type lithium solid electrolyte material. Both ends of sample 11 are supported by supports 12 arranged below sample 11, and sample 11 is sandwiched between supports 13 arranged at the center above sample 11. Support 12 is arranged on pedestal 14, and a load is applied to the lower side of support 13 by support fixture 15, and the load is measured by a load cell. In this embodiment, since the size of sample 11 is smaller than the JIS R1601 standard, the diameter of lower support 12 is 2 mm, the diameter of upper support 13 is 3 mm, and the center-to-center distance D of support 12 is 4 mm.

[0056] FIG. 5 is a table showing the measurement results of the three-point bending strength of Example 1. The measurement was performed on 10 samples. As shown in FIG. 5, the single crystal garnet-type lithium solid electrolyte material of Example 1 had a three-point bending strength ranging from 47.5 MPa to 155.5 MPa, with an average of 104.2 MPa. In contrast, the sintered garnet-type lithium solid electrolyte material of Comparative Example 1 had an average three-point bending strength of 46.5 MPa when measured on 14 samples. Therefore, it was confirmed that the single crystal Example had an average three-point bending strength that was more than twice that of the sintered comparative example.

[0057] <Surface roughness Ra measurement> Next, the surface roughness Ra of the single crystal garnet-type lithium solid electrolyte material of Example 1 and the sintered garnet-type lithium solid electrolyte material of Comparative Example 1 was measured with a measurement range set to approximately 300 μm × 200 μm. A laser microscope (VK-X260) manufactured by Keyence Corporation was used for the measurement. The surface roughness Ra measurement results for Example 1, which is a single crystal, were in the range of 0.1 nm to 10 nm, with an average of 6 nm. In contrast, for Comparative Example 1, which is a sintered body, the surface roughness Ra was in the range of 600 nm to 1000 nm, with an average of 790 nm. While the single crystal garnet-type lithium solid electrolyte material had a favorable surface roughness Ra of 0.1 nm to 10 nm, the sintered body could not have a surface roughness Ra of 10 nm or less due to the influence of voids.

[0058] FIG. 6 is a graph showing the relationship between surface roughness and three-point bending strength of a garnet-type lithium solid electrolyte material. The dots plotted in the graph represent the measurement results for the sintered body, and the crosses plotted represent the values ​​for the single crystal. The horizontal axis represents the surface roughness Sa (μm), and the vertical axis represents the three-point bending strength (MPa). Here, Sa (μm) on the horizontal axis represents the surface roughness Ra measurement expanded from one-dimensional to two-dimensional measurement. As shown in FIG. 6, the surface roughness Sa of the sintered body of Comparative Example 1 was 0.6 μm (600 nm) to 1.0 μm (1000 nm), which is much larger than that of Example 1 of the single crystal, and the three-point bending strength was also less than half that of the Example.

[0059] Next, the relationship between the surface roughness Ra and the lithium ion conductivity and the internal short-circuit critical current density of the single-crystal garnet-type lithium solid electrolyte material was measured. For Comparative Example 2 and Examples 2 and 3, a single crystal of the garnet-type lithium solid electrolyte material 1 was sliced, ground, and polished to form wafers with a diameter of 7 mm and a thickness of 1 mm, and gold films were formed on the front and back surfaces by sputtering to obtain samples. In Comparative Example 2, no polishing step using an abrasive was performed, and only surface grinding using a grinding device was performed, resulting in a surface roughness Ra of 400 nm. In Example 2, a polishing (coarse polishing) step was performed using abrasive grains with a grain size of 1 to 2 μm, resulting in a surface roughness Ra of 10 nm. In Example 3, a polishing step was performed using abrasive grains with a grain size of 0.5 μm or less, resulting in a surface roughness Ra of 5 nm.

[0060] <Measurement and calculation of lithium ion conductivity> Impedance measurements were performed on the obtained Comparative Example 2 and Examples 2 and 3. For the measurements, an Impedance Analyzer 1260 manufactured by Solartron Analytical was used, and the measurement temperature was room temperature, the measurement frequency was 1 Hz to 32 MHz, and the applied voltage was 100 mV. The obtained impedance measurements were plotted using a Nyquist method, and the lithium ion conductivity was calculated from the diameter of the semicircle that appeared. The measurement results of the ion conductivity (lithium ion conductivity) were 0.85 mS / cm, 0.83 mS / cm, and 0.83 mS / cm for Comparative Example 2 and Examples 2 and 3, respectively. Since Comparative Example 2 and Examples 2 and 3 were all single crystals, the lithium ion conductivity was good, at 0.8 mS / cm or higher, and it was found that it was independent of the surface roughness Ra.

[0061] <Measurement of internal short circuit critical current density> Next, Li foil was attached to the samples processed in the same manner as in Comparative Example 2 and Examples 2 and 3 to obtain Comparative Example 3 and Examples 4 and 5. The internal short circuit critical current density was measured by a direct current test. For the measurement, a Modulab manufactured by Solartron Analytical was used, the measurement temperature was room temperature, and the electrode was pressed against the Li foil to obtain a current of 0.1 mA / cm. 2The current value was increased at intervals of 0.2 mA / cm, and a direct current was applied for 30 minutes in each measurement, and the current density at which a short circuit occurred was measured. 2 In Examples 4 and 5, a short circuit occurred at 0.5 mA / cm 2 Therefore, for single-crystal garnet-type lithium solid electrolyte materials, by setting the surface roughness Ra to 10 nm or less, the internal short circuit critical current density can be reduced to 0.5 mA / cm 2 I found out that I can do more than that.

[0062] Figure 7 is a table showing the relationship between the surface roughness of garnet-type lithium solid electrolyte materials and the lithium ion conductivity and internal short circuit critical current density. As mentioned above, in single-crystal garnet-type lithium solid electrolyte materials, the lithium ion conductivity is good at 0.8 mS / cm or more, and is independent of the surface roughness Ra. Furthermore, when the surface roughness Ra is 10 nm or less, the internal short circuit critical current density is 0.5 mA / cm. 2 It can do more than that.

[0063] As described above, in this embodiment, the garnet-type lithium solid electrolyte material 1 is made of a single crystal and has a surface roughness Ra of 0.1 nm or more and 10 nm or less on the front and back surfaces, thereby suppressing the interface resistance, improving the lithium ion conductivity, suppressing internal short circuits, and simplifying the surface processing process. Furthermore, by using at least a part of the garnet-type lithium solid electrolyte material in a battery, a battery with high lithium ion conductivity and a large internal short circuit critical current density can be obtained, thereby realizing a high-power all-solid-state battery.

[0064] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0065] 1...Garnet-type lithium solid electrolyte material 2...Positive electrode 3...Negative electrode 10...Battery 11...Sample 12,13...Support 14...Pedestal 15...Support fixing part

Claims

1. It is made of a single crystal, and the surface roughness Ra of the front and back surfaces is in the range of 0.1 nm to 10 nm, The three-point bending strength is in the range of 47.5 MPa or more and 155.5 MPa or less, A garnet-type lithium solid electrolyte material characterized by being Li 7-x-y La 3 Zr 2-x-y Nb x Ta y O 12 (0.2≦x+y≦1.0, 0≦x≦1.0, 0≦y≦1.0) or Li 7-3x Ga x La 3 Zr 2 O 12 (0.08≦x≦0.5).

2. 2. The garnet-type lithium solid electrolyte material according to claim 1, A garnet-type lithium solid electrolyte material, wherein the single crystal is a single, self-supporting crystal having a thickness.

3. 3. The garnet-type lithium solid electrolyte material according to claim 2, A garnet-type lithium solid electrolyte material, characterized in that the thickness is in the range of 20 μm or more and 1 mm or less.

4. The garnet-type lithium solid electrolyte material according to claim 3, A garnet-type lithium solid electrolyte material, characterized in that the thickness is in the range of 30 μm or more and 0.5 mm or less.

5. 5. The garnet-type lithium solid electrolyte material according to claim 1, A garnet-type lithium solid electrolyte material having a circular planar shape or a circular shape with an orientation flat surface formed thereon and a diameter of 30 mm or more.

6. 5. The garnet-type lithium solid electrolyte material according to claim 1, The planar shape is rectangular, and the area of ​​the rectangle is 730 mm ２ The garnet-type lithium solid electrolyte material is characterized by the above.

7. A battery comprising at least a portion of the garnet-type lithium solid electrolyte material according to any one of claims 1 to 6.

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