Lithium-based solid electrolyte, inorganic solid electrolyte, method for manufacturing lithium-based solid electrolyte, modified positive electrode active material, modified negative electrode active material, all-solid-state secondary battery, electrode sheet for all-solid-state secondary battery, solid electrolyte sheet, electrode for all-solid-state secondary battery

Abstract

Provided is a lithium-based solid electrolyte having excellent ion conductivity, an inorganic solid electrolyte, a method for producing a lithium-based solid electrolyte, a modified positive electrode active material, a modified negative electrode active material, a full-solid-state secondary battery, an electrode sheet for a full-solid-state secondary battery, a solid electrolyte sheet, and an electrode for a full-solid-state secondary battery. The lithium-based solid electrolyte of the present invention contains lithium tetraborate in an amorphous state, water, and a lithium salt.

Description

Technical Field

[0001] This invention relates to a lithium-based solid electrolyte, an inorganic solid electrolyte, a method for manufacturing a lithium-based solid electrolyte, a modified positive electrode active material, a modified negative electrode active material, an all-solid-state secondary battery, an electrode sheet for an all-solid-state secondary battery, a solid electrolyte sheet, and an electrode for an all-solid-state secondary battery. Background Technology

[0002] Previously, liquid electrolytes with high ionic conductivity were used in lithium-ion secondary batteries. However, liquid electrolytes are flammable, posing safety concerns. Furthermore, their liquid form makes miniaturization difficult, and capacity limitations become an issue when batteries are enlarged.

[0003] In contrast, all-solid-state lithium-ion secondary batteries are among the next-generation batteries capable of solving these problems. In all-solid-state batteries, a solid electrolyte with good ionic conductivity is required to achieve the desired charge-discharge characteristics. For example, Patent Document 1 discloses a solid electrolyte that can be used in all-solid-state lithium-ion secondary batteries. Patent Document 1 discloses a solid electrolyte based on lithium oxide.

[0004] Previous technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-052755 Summary of the Invention

[0007] The technical problem to be solved by the invention

[0008] Patent document 1 discloses a conductivity of 10. -5 S·cm -1 However, in recent years, there has been a demand to further improve the conduction rate.

[0009] The objective of this invention is to provide a lithium-based solid electrolyte with excellent ion conductivity.

[0010] Furthermore, the present invention also provides a method for manufacturing an inorganic solid electrolyte, a lithium-based solid electrolyte, a modified positive electrode active material, a modified negative electrode active material, an all-solid-state secondary battery, an electrode sheet for an all-solid-state secondary battery, a solid electrolyte sheet, and an electrode for an all-solid-state secondary battery.

[0011] means for solving technical problems

[0012] In order to solve the above-mentioned problems, the inventors conducted in-depth research and completed the present invention with the following structure.

[0013] (1) A lithium-based solid electrolyte comprising lithium tetraborate in an amorphous state, water and lithium salt.

[0014] (2) A lithium-based solid electrolyte comprising lithium tetraborate, water and lithium salt that have been mechanically ground.

[0015] (3) The lithium-based solid electrolyte according to (1), wherein,

[0016] The molar ratio of lithium salt to lithium tetraborate is 0.001 to 1.5.

[0017] The molar ratio of water to lithium tetraborate is 3 to 15.

[0018] (4) The lithium-based solid electrolyte according to (2), wherein,

[0019] The molar ratio of lithium salt to lithium tetraborate is 0.001 to 1.5.

[0020] The molar ratio of water to lithium tetraborate is 3 to 15.

[0021] (5) A lithium-based solid electrolyte comprising amorphous LiB3O5 and Li3B 11 O 18 Or Li3B7O 12 Water and lithium salts.

[0022] (6) A lithium-based solid electrolyte according to any one of (1) to (5), wherein,

[0023] The lithium salt is the compound represented by formula (1) described later.

[0024] (7) A lithium-based solid electrolyte, wherein...

[0025] Lithium-based solid electrolytes contain Li, B, and O.

[0026] Lithium-based solid electrolytes also contain two or more specific elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H, and N.

[0027] The molar ratio of B to Li is greater than 1.50 and less than 2.43.

[0028] The molar ratio of O to Li is greater than 2.34 and less than 6.86.

[0029] The molar ratio of each specific element to Li is greater than 0.001 and less than 0.17.

[0030] (8) A lithium-based solid electrolyte, wherein...

[0031] Lithium-based solid electrolytes contain Li, B, and O.

[0032] Lithium-based solid electrolytes also contain two or more specific elements selected from Group 4, Group 15, Group 16, Group 17 of the periodic table, Si, C, Sc, Y, and H.

[0033] When the molar amount of B in a lithium-based solid electrolyte is set to 4.00 to represent the molar amounts of Li, O, and specific elements,

[0034] The molar amount of Li is 1.58–3.49.

[0035] The molar amount of 0 is 6.23–25.00.

[0036] The molar amounts of specific elements range from 0.001 to 10.00.

[0037] (9) A lithium-based solid electrolyte according to any one of (1) to (8), wherein,

[0038] In the infrared absorption spectrum, 3000–3500 cm⁻¹ -1 The maximum absorption intensity in the wavenumber region is relative to 800–1600 cm⁻¹ -1 The ratio of the maximum absorption intensity in the wavenumber region is more than 1 / 5.

[0039] (10) A lithium-based solid electrolyte comprising Li, B and O, and also satisfying any one of the following requirements X to Z.

[0040] (11) The lithium-based solid electrolyte according to (10) further comprises one or more specific elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H and N.

[0041] (12) A lithium-based solid electrolyte according to any one of (1) to (11), wherein,

[0042] Solid was subjected to treatment at 120℃ 7 The full width at half maximum (FWHM) of peaks with chemical shifts in the range of -100 to +100 ppm obtained during Li-NMR measurements is relative to the values ​​obtained during solid-state ... 7 In Li-NMR measurements, the proportion of the full width at half maximum (FWHM) of peaks with chemical shifts in the range of -100 to +100 ppm is less than 50%.

[0043] (13) A lithium-based solid electrolyte according to any one of (1) to (12), wherein,

[0044] Solid was subjected to treatment at 20℃ 7 When the first peak in the spectrum obtained during Li-NMR determination appears in the range of -100 to +100 ppm, waveform separation is performed. Then, a second peak with a full width at half maximum (FWHM) of less than 5 ppm appears in the range of chemical shift of -3 to 3 ppm. The area intensity of the second peak is more than 0.5% of the area intensity of the first peak.

[0045] (14) The lithium-based solid electrolyte according to (7), wherein,

[0046] In the Raman spectrum at 600–850 cm⁻¹ -1 The coefficient of determination obtained by linear regression analysis based on the least squares method within the wavenumber region is above 0.9400.

[0047] (15) The lithium-based solid electrolyte according to (7), wherein,

[0048] The mass reduction rate when heated to 800°C is 20-40% by mass.

[0049] (16) An inorganic solid electrolyte having conductivity of ions selected from metals belonging to Group 1 of the periodic table and elements belonging to Group 2 of the periodic table.

[0050] Inorganic solid electrolytes contain metals selected from Group 1 and Group 2 elements of the periodic table, as well as B and O.

[0051] Inorganic solid electrolytes also contain two or more elements selected from Group 3, Group 4, Group 13, Group 14, Group 15, Group 16, Group 17 of the periodic table, and specific elements from H.

[0052] Inorganic solid electrolytes are amorphous.

[0053] The following requirement R is satisfied.

[0054] (17) An inorganic solid electrolyte comprising: a compound comprising a metal element selected from Group 1 and Group 2 of the periodic table, B and O; water; and a salt comprising a metal element selected from Group 1 and Group 2 of the periodic table.

[0055] (18) The inorganic solid electrolyte according to (17), wherein,

[0056] The compound is amorphous.

[0057] (19) A method for manufacturing a lithium-based solid electrolyte, wherein the method is any one of the lithium-based solid electrolytes described in (1) to (15).

[0058] The method for manufacturing the lithium-based solid electrolyte includes:

[0059] Step 1: Mechanical grinding is performed on lithium oxides containing Li and B;

[0060] Step 2 involves mixing the product obtained in Step 1 with water; and

[0061] Step 3 involves removing water from the dispersion obtained in Step 2 to obtain a lithium-based solid electrolyte.

[0062] The method for manufacturing the lithium-based solid electrolyte satisfies any one of requirements 1 to 3 described below.

[0063] (20) The method for manufacturing a lithium-based solid electrolyte according to (19) satisfies requirement 1.

[0064] Before step 1, in the absence of a specific element source, there is a step 0 that performs mechanical grinding on lithium oxide containing Li and B.

[0065] (21) A modified positive electrode active material, having a positive electrode active material and a coating layer disposed on the positive electrode active material.

[0066] The coating layer comprises any one of (1) to (15) a lithium-based solid electrolyte or any one of (16) to (18) an inorganic solid electrolyte.

[0067] (22) A modified negative electrode active material having a negative electrode active material and a coating layer disposed on the negative electrode active material.

[0068] The coating layer comprises any one of (1) to (15) a lithium-based solid electrolyte or any one of (16) to (18) an inorganic solid electrolyte.

[0069] (23) An all-solid-state secondary battery, which sequentially comprises a positive electrode active material layer, a solid electrolyte layer and a negative electrode active material layer.

[0070] At least one of the positive electrode active material layer, the solid electrolyte layer and the negative electrode active material layer contains a lithium-based solid electrolyte as described in any one of (1) to (15) or an inorganic solid electrolyte as described in any one of (16) to (18).

[0071] (24) An electrode sheet for an all-solid-state secondary battery, comprising a lithium-based solid electrolyte as described in any one of (1) to (15) or an inorganic solid electrolyte as described in any one of (16) to (18).

[0072] (25) A solid electrolyte sheet comprising any one of (1) to (15) a lithium-based solid electrolyte or any one of (16) to (18) an inorganic solid electrolyte.

[0073] (26) An electrode for an all-solid-state secondary battery, comprising: an active material; an active material layer comprising a lithium-based solid electrolyte as described in any one of (1) to (15) or an inorganic solid electrolyte as described in any one of (16) to (18); and a current collector.

[0074] Invention Effects

[0075] According to the present invention, a lithium-based solid electrolyte with excellent ion conductivity can be provided.

[0076] Furthermore, according to the present invention, a method for manufacturing an inorganic solid electrolyte, a lithium-based solid electrolyte, a modified positive electrode active material, a modified negative electrode active material, an all-solid-state secondary battery, an electrode sheet for an all-solid-state secondary battery, a solid electrolyte sheet, and an electrode for an all-solid-state secondary battery can also be provided. Attached Figure Description

[0077] Figure 1 This refers to the solid lithium-based solid electrolyte of the first embodiment of the present invention, which is carried out at 20°C or 120°C. 7 An example of a spectrum obtained during Li-NMR (Nuclear Magnetic Resonance) measurement.

[0078] Figure 2 This indicates the solid form of lithium tetraborate crystals produced at 20°C or 120°C. 7 A diagram of an example of the spectrum obtained during Li-NMR determination.

[0079] Figure 3 This refers to the solid electrolyte of the first embodiment of the lithium-based solid electrolyte of the present invention, which is carried out at 20°C. 7 A diagram of an example of the spectrum obtained during Li-NMR determination.

[0080] Figure 4 It is Figure 3 The diagram shown illustrates the waveform separation of the peaks.

[0081] Figure 5 This is a diagram showing an example of the Raman spectrum of the first embodiment of the lithium-based solid electrolyte of the present invention.

[0082] Figure 6 This is a diagram showing the Raman spectrum of a typical lithium tetraborate crystal.

[0083] Figure 7 This is a schematic cross-sectional view illustrating a preferred embodiment of the all-solid-state lithium-ion secondary battery of the present invention.

[0084] Figure 8 This is a graph representing an example of the reduced pair distribution function G(r) obtained by measuring the X-ray total scattering of a specific lithium tetraborate, as described later.

[0085] Figure 9 This is a diagram showing an example of the X-ray total scattering profile of a specific lithium tetraborate.

[0086] Figure 10 It means based on Figure 9 A figure showing an example of the structure factor S(Q) of the X-ray total scattering profile obtained in [the study].

[0087] Figure 11 This is a diagram showing an example of an X-ray diffraction pattern used to illustrate element Y.

[0088] Figure 12 The reduced two-body distribution function G(r) obtained from the X-ray total scattering measurement of the crystal powder of Comparative Example 1 is shown in the figure.

[0089] Figure 13 The X-ray diffraction pattern of the crystal powder of Comparative Example 1 is shown in the figure.

[0090] Figure 14 The X-ray diffraction pattern of the lithium-based solid electrolyte of Example 3 is shown in the figure.

[0091] Figure 15 This is an example of the Raman spectrum used to illustrate requirement T.

[0092] Figure 16 An example of the reduced-body distribution function G(r) obtained from the X-ray total scattering measurement of the fourth embodiment of the lithium-based solid electrolyte of the present invention is shown. Detailed Implementation

[0093] The present invention will now be described in detail.

[0094] In addition, in this specification, the use of “~” refers to the range of values ​​included by taking the values ​​before and after “~” as the lower and upper limits.

[0095] As a characteristic feature of the first and second embodiments of the lithium-based solid electrolyte of the present invention, it can be cited that it contains various elements in specified amounts. In particular, it can be cited that the content of O (oxygen element) is relatively high, and that it contains specified amounts of specific element A and specific element B. In addition, it is speculated that O exists not only as BO3 or BO4 in the lithium-based solid electrolyte, but also as water or OH groups, and that a hydration layer with good ionic conductivity due to the high content of O is formed on the surface side of the lithium-based solid electrolyte. Furthermore, it is speculated that such a lithium-based solid electrolyte also has excellent adhesion, which also contributes to the improvement of ionic conductivity.

[0096] Furthermore, a characteristic feature of the third embodiment of the lithium-based solid electrolyte of the present invention is that it is used by mixing mechanically milled lithium tetraborate with a predetermined component (water, lithium salt). As described later, the mechanically milled lithium tetraborate has a short-range ordered structure related to the interatomic distances of BO and BB, but almost no long-range ordered structure. In addition, the aforementioned interatomic distance of BO refers to the distance between B and B, which is close to the interatomic distance of BB. When this lithium tetraborate is used simultaneously with the predetermined component, a soft hydration layer is easily formed on the surface of the lithium tetraborate. This hydration layer contains a large amount of lithium derived from the lithium salt, and as a result, it is presumed that the ionic conductivity is good. In addition, another characteristic feature of the third embodiment is that it is used by mixing amorphous lithium tetraborate with a predetermined component (water, lithium salt). If amorphous lithium tetraborate is used simultaneously with the specified composition, a soft hydrated layer is easily formed on the surface of lithium tetraborate. This hydrated layer contains a large amount of lithium derived from lithium salts, and as a result, it is presumed that the ionic conductivity is good.

[0097] Furthermore, as a characteristic feature of the fourth embodiment of the lithium-based solid electrolyte of the present invention, the following elements X to Z can be cited. Element X mainly indicates that the lithium-based solid electrolyte has a short-range ordered structure, and element Y mainly refers to the near absence of a crystalline structure in the lithium-based solid electrolyte, and its amorphous state. Furthermore, element Z indicates that the lithium-based solid electrolyte contains a large number of OH groups or a large amount of water. Based on these results, it is speculated that a soft hydration layer is formed on the surface side of the lithium-based solid electrolyte, and the presence of this hydration layer improves ionic conductivity.

[0098] Furthermore, as a characteristic feature of the fifth embodiment of the lithium-based solid electrolyte of the present invention, examples include the use of amorphous LiB3O5 and Li3B... 11 O 18 Or Li3B7O 12This is used when mixed with specified components (water, lithium salt). The following is speculation: if amorphous LiB3O5 and Li3B are used simultaneously... 11 O 18 Or Li3B7O 12 And the specified components, then in LiB3O5, Li3B 11 O 18 Or Li3B7O 12 The surface readily forms a soft hydration layer containing a large amount of lithium derived from lithium salts, resulting in good ionic conductivity.

[0099] Furthermore, the inorganic solid electrolyte of the present invention exhibits the desired effect by satisfying the structure described later.

[0100] Hereinafter, various embodiments of the lithium-based solid electrolyte and inorganic solid electrolyte of the present invention will be described in detail.

[0101] <<First Implementation>>

[0102] Hereinafter, a first embodiment of the lithium-based solid electrolyte of the present invention will be described.

[0103] Lithium-based solid electrolytes

[0104] The first embodiment of the lithium-based solid electrolyte of the present invention comprises Li (lithium), B (boron) and O (oxygen).

[0105] Furthermore, the first embodiment of the lithium-based solid electrolyte of the present invention further includes two or more specific elements selected from F (fluorine), Cl (chlorine), Br (bromine), I (iodine), S (sulfur), P (phosphorus), Si (silicon), Se (selenium), Te (tellurium), C (carbon), Sb (antimony), As (arsenic), Sc (scandium), Y (yttrium), Zr (zirconium), Ti (titanium), Hf (hafnium), H (hydrogen), and N (nitrogen). The first embodiment of the lithium-based solid electrolyte of the present invention may include three or more specific elements. From the viewpoint of superior ion conductivity (hereinafter also referred to as "the viewpoint of superior effect of the present invention"), the lithium-based solid electrolyte preferably includes 2 to 5 specific elements, more preferably 2 to 4.

[0106] The first embodiment of the lithium-based solid electrolyte of the present invention preferably contains two or more specific elements selected from the group consisting of F, S, N, P and C, more preferably contains two or more specific elements selected from F, S, C and N, and even more preferably contains three specific elements consisting of F, S and N.

[0107] In the first embodiment of the lithium-based solid electrolyte of the present invention, the molar ratio of B to Li (B / Li) is greater than 1.50 and less than 2.43. That is, in the first embodiment of the lithium-based solid electrolyte of the present invention, the relative value of the molar content of B when the molar content of Li is set to 1.0 is greater than 1.50 and less than 2.43.

[0108] From the viewpoint of achieving better results with the present invention, the preferred molar ratio of B to Li is 1.70 to 2.30, and more preferably 1.90 to 2.10.

[0109] In the first embodiment of the lithium-based solid electrolyte of the present invention, the molar ratio of O to Li (O / Li) is greater than 2.34 and less than 6.86. That is, in the first embodiment of the lithium-based solid electrolyte of the present invention, when the molar content of Li is set to 1.0, the relative value of the molar content of O is greater than 2.34 and less than 6.86.

[0110] From the viewpoint of achieving better results with the present invention, the preferred molar ratio of O to Li is 3.00 to 6.50, more preferably 3.50 to 6.00, even more preferably 4.50 to 6.00, and particularly preferably 5.00 to 6.00.

[0111] In the first embodiment of the lithium-based solid electrolyte of the present invention, the molar ratio of each specific element to Li (specific element / Li) is greater than 0.001 and less than 0.17. That is, in the first embodiment of the lithium-based solid electrolyte of the present invention, when the molar content of Li is set to 1.0, the relative value of the molar content of each specific element is greater than 0.001 and less than 0.17.

[0112] As described above, in the first embodiment of the lithium-based solid electrolyte of the present invention, two or more specific elements are included. Therefore, for example, when the first embodiment of the lithium-based solid electrolyte of the present invention includes two specific elements, namely, specific element A and specific element B (a different type of specific element A), the molar ratio of specific element A to Li and the molar ratio of specific element B to Li are both greater than 0.001 and less than 0.17. Furthermore, for example, when the first embodiment of the lithium-based solid electrolyte of the present invention includes three specific elements, namely, specific element A, specific element B (a different type of specific element A), and specific element C (a different type of specific element A and B), the molar ratio of specific element A to Li, the molar ratio of specific element B to Li, and the molar ratio of specific element C to Li are both greater than 0.001 and less than 0.17.

[0113] From the viewpoint of achieving better results from the present invention, the molar ratio of each specific element to Li is preferably 0.003 to 0.15, more preferably 0.01 to 0.14.

[0114] In the first embodiment of the lithium-based solid electrolyte of the present invention, the contents of Li, B, and specific elements are determined by known elemental analysis. For example, Li and B are analyzed using ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry); one specific element, such as N, is analyzed using an inert gas fusion method; and one specific element, such as F and S, is analyzed using combustion ion chromatography. Regarding O, the analytical masses of all elements except O can be added together and the result calculated as the difference from the total powder content. Furthermore, the method for calculating the content of each element is not limited to the above; for example, the content of other elements can be estimated based on the analytical results of one element, taking into account the structure of the compound used.

[0115] The molar ratio of B to Li, the molar ratio of O to Li, and the molar ratio of each specific element to Li are calculated from the content of each element by elemental analysis.

[0116] One preferred embodiment of the lithium-based solid electrolyte of the present invention is a lithium-based solid electrolyte comprising Li, B, O, F, S, and N, wherein the molar ratio of B to Li is greater than 1.50 and less than 2.43, the molar ratio of O to Li is greater than 2.34 and less than 6.86, the molar ratio of F to Li is greater than 0.001 and less than 0.17, the molar ratio of S to Li is greater than 0.001 and less than 0.17, and the molar ratio of N to Li is greater than 0.001 and less than 0.17.

[0117] The preferred range of the above molar ratio is as described above.

[0118] In addition, the first embodiment of the lithium-based solid electrolyte of the present invention may include Li, B, O and other elements other than specific elements.

[0119] The manufacturing method of the lithium-based solid electrolyte of the present invention according to the first embodiment will be described in detail later, but the lithium-based solid electrolyte of the present invention is preferably manufactured by a manufacturing method accompanied by mechanical milling. For example, it is speculated that by mechanically milling the raw materials (e.g., lithium oxides containing Li and B) of the lithium-based solid electrolyte of the first embodiment of the present invention, the crystalline components in the raw materials can be amorphized, and as a result, a hydrated layer with excellent ion conductivity becomes easier to form.

[0120] Furthermore, from the viewpoint of achieving superior effects, the first embodiment of the lithium-based solid electrolyte of the present invention was tested at 120°C. 7 The full width at half maximum (FWHM) of the peaks with chemical shifts in the range of -100 to +100 ppm obtained during Li-NMR measurements is comparable to that of the solid lithium-based solid electrolyte of the first embodiment of the present invention, which was subjected to Li-NMR measurements at 20°C. 7 In Li-NMR measurements, the proportion of the full width at half maximum (FWHM) of peaks with chemical shifts in the range of -100 to +100 ppm is preferably 50% or less, more preferably 40% or less, and even more preferably 35% or less. There is no particular limitation on the lower limit, but it is usually 10% or more.

[0121] The full width at half peak (FWHM) refers to the width (ppm) at half the height (H) of the peak (H / 2).

[0122] The following uses Figure 1 The above characteristics will be explained.

[0123] exist Figure 1 The image shows a first embodiment of the lithium-based solid electrolyte of the present invention, which was subjected to treatment at 20°C or 120°C. 7 An example of a spectrum obtained during Li-NMR determination.

[0124] Figure 1 The spectrum of the solid line shown in the lower part of the image was obtained by solid-state chromatography at 20°C. 7 The spectrum obtained during Li-NMR determination, in Figure 1 The spectrum shown by the dashed line at the top of the image was obtained from a solid-state test at 120°C. 7 The spectrum obtained during Li-NMR determination.

[0125] Generally speaking, in solids 7 In Li-NMR measurements, in Li + When the mobility is high, the obtained peak is sharper. Figure 1 In the method shown, if the spectrum at 20°C is compared with the spectrum at 120°C, the spectrum at 120°C becomes sharper. That is, in Figure 1 The lithium-based solid electrolyte shown in the figure contains Li + The improved mobility. It is believed that this type of lithium-based solid electrolyte originates from an amorphous structure, making it easier to plastically deform, and through Li... + The leap in performance is excellent, and the effect of the present invention is even better.

[0126] Additionally, for example, regarding lithium tetraborate crystals, solid-state treatment was performed at 20°C or 120°C.7 When measuring Li-NMR, it is shown in Figure 2 The lower side, represented by the solid line, shows the spectrum measured at 20°C and is shown in the figure. Figure 2 The spectrum measured at 120°C, indicated by the dashed line on the upper side, tends to have roughly the same shape.

[0127] The above solid 7 The determination conditions for Li-NMR are as follows.

[0128] Specifically, a 4mm HX CP-MAS probe was used, and the measurements were performed using a single pulse method with a 90° pulse width of 3.2μs, an observation frequency of 155.546MHz, an observation width of 1397.6ppm, a repetition time of 15sec, a cumulative count of 1 time, and a MAS rotation speed of 0Hz.

[0129] Furthermore, from the viewpoint of achieving superior effects, the first embodiment of the lithium-based solid electrolyte of the present invention was tested at 20°C. 7 When performing Li-NMR measurements, if the first peak in the spectrum obtained appears in the range of -100 to +100 ppm and is waveform separated, a second peak with a full width at half maximum (FWHM) of 5 ppm or less in the range of -3 to 3 ppm is also present. Preferably, the area intensity of the second peak is 0.5% or more of the area intensity of the first peak. More preferably, this area intensity ratio is 2% or more, and even more preferably 15% or more. There is no particular upper limit to this area intensity ratio, but in most cases it is 50% or less.

[0130] The following uses Figure 3 and Figure 4 The above characteristics will be explained.

[0131] exist Figure 3 The image shows a first embodiment of the lithium-based solid electrolyte of the present invention, which was subjected to treatment at 20°C. 7 An example of a spectrum obtained during Li-NMR determination. For example... Figure 3 As shown, in the first embodiment of the lithium-based solid electrolyte of the present invention, a peak (corresponding to the first peak) was observed in the range of -100 to +100 ppm. Within this first peak, small peaks were observed, such as those near the chemical shift of 0 ppm, surrounded by dashed lines. As described above, it is believed that in Li... + When the motion is high, sharp peaks can be observed, thus producing an effect.

[0132] then, Figure 4 The image shows waveform separation of the first peak. For example... Figure 4As shown, the first peak is separated by the waveform into a smaller peak (equivalent to the second peak) represented by a solid line and a larger peak represented by a dashed line. The aforementioned second peak is a peak with a chemical shift in the range of -3 to 3 ppm and a full width at half maximum (FWHM) of less than 5 ppm.

[0133] In the first embodiment of the lithium-based solid electrolyte of the present invention, by Figure 4 The solid line represents the area intensity of the second peak relative to that of the peak formed by... Figure 3 The ratio of the area intensity of the first peak (the peak before waveform separation) to the area intensity of the second peak (the area intensity of the first peak) is within the range mentioned above.

[0134] As a method for waveform separation, one example is the use of well-known software, such as WaveMetrics, Inc.'s graphics processing software Igor Pro.

[0135] Furthermore, from the viewpoint of achieving superior effects, in the infrared absorption spectrum of the first embodiment of the lithium-based solid electrolyte of the present invention, the 3000–3500 cm⁻¹... -1 The maximum absorption intensity in the wavenumber region is relative to 800–1600 cm⁻¹ -1 The ratio of the maximum absorption intensity in the wavenumber region is preferably 1 / 5 or more. From the viewpoint of further enhancing the effects of the present invention, the ratio is preferably 3 / 10 or more, more preferably 2 / 5 or more. There is no particular upper limit, but 1 or less is preferred.

[0136] In the infrared absorption spectrum of 3000–3500 cm⁻¹ -1 OH stretching vibration modes were observed in the wavenumber region, from 800 to 1600 cm⁻¹. -1 A BO ​​stretching vibration mode was observed in the wavenumber region. In the first embodiment of the lithium-based solid electrolyte of the present invention, a strong absorption intensity originating from the OH stretching vibration mode was observed, indicating that the first embodiment of the lithium-based solid electrolyte of the present invention contains multiple OH groups or a large amount of water. It is believed that in this type of lithium-based solid electrolyte, lithium ions become more mobile, resulting in improved ionic conductivity.

[0137] Additionally, in the range of 800–1600 cm -1 Vibrational modes originating from lithium salts can also be observed in the wavenumber region.

[0138] The conditions for the infrared absorption spectroscopy measurement are as follows.

[0139] Specifically, the objective lens used was a 32x Cassegrain type (NA 0.65), the detector was an MCT-A, and the measurement range was 650–4000 cm. -1 Resolution: 4cm -11. Sample cell: The test is performed using a diamond cell.

[0140] In addition, regarding the obtained infrared absorption spectrum, corrections were performed to remove signals from water and CO2 originating from the atmosphere, and a background offset correction was further applied to set the absorption intensity to 0.

[0141] Furthermore, when measuring the infrared absorption spectrum of the lithium-based solid electrolyte of the present invention according to the first embodiment, the measurement was performed in air after vacuum drying at 40°C for 2 hours.

[0142] Furthermore, from the viewpoint of superior performance of the present invention, the Raman spectrum of the first embodiment of the lithium-based solid electrolyte of the present invention is in the range of 600–850 cm⁻¹. -1 The coefficient of determination obtained by linear regression analysis based on the least squares method in the wavenumber region is preferably above 0.9400.

[0143] Furthermore, from the viewpoint of achieving better results with the present invention, the aforementioned coefficient of determination is more preferably 0.9600 or higher. There is no particular upper limit, but 1.0000 can be cited as an example.

[0144] The following uses Figure 5 The above will be explained.

[0145] Figure 5 The image shows an example of the Raman spectrum of the first embodiment of the lithium-based solid electrolyte of the present invention. The image shows the Raman spectrum from 600 to 850 cm⁻¹, with Raman intensity on the vertical axis and Raman shift on the horizontal axis. -1 In the wavenumber region, the coefficients of determination (R²) obtained by linear regression analysis based on the least squares method are calculated. 2 That is, in Figure 5 Raman spectra of 600–850 cm⁻¹ -1 In the wavenumber region, the regression line is obtained using the least squares method. Figure 5 (The thick dashed line in the middle), and calculate the coefficient of determination R of its regression line. 2 In addition, the coefficient of determination is set to a value between 0 (no linear correlation) and 1 (perfect linear correlation of the measured values) based on the linear correlation of the measured values.

[0146] In the first embodiment of the lithium-based solid electrolyte of the present invention, as Figure 5 As shown, in the range of 600–850 cm -1 In the wavenumber region, almost no peaks were observed, resulting in a high coefficient of determination.

[0147] In addition, the aforementioned coefficient of determination R 2 This is equivalent to the square of the correlation coefficient (Pearson product-moment correlation coefficient). More specifically, in this specification, the determination coefficient R...2 The calculation is performed using the following formula. In the formula, x1 and y1 represent the wavenumber and the corresponding Raman intensity in the Raman spectrum, x2 represents the (additive) average of the wavenumbers, and y2 represents the (additive) average of the Raman intensities.

[0148] [Formula 1]

[0149]

[0150] on the other hand, Figure 6 The image shows the Raman spectrum of a typical lithium tetraborate crystal. (Example:) Figure 6 As shown, in the case of typical lithium tetraborate crystals, the 716–726 cm⁻¹ value originates from its structure. -1 and 771~785cm -1 A peak was observed in the wavenumber region.

[0151] In the presence of this type of peak, it is located between 600 and 850 cm⁻¹. -1 In the wavenumber region, when performing linear regression analysis based on the least squares method to calculate the coefficient of determination, its coefficient of determination is less than 0.9400.

[0152] That is, the aforementioned coefficient of determination of 0.9400 or higher means that in the first embodiment of the lithium-based solid electrolyte of the present invention, it almost does not contain the crystal structure contained in typical lithium tetraborate crystals. Therefore, it is considered that, as a result, the first embodiment of the lithium-based solid electrolyte of the present invention has Li + It has excellent jumping ability.

[0153] Furthermore, from the viewpoint of achieving better results from the present invention, it is preferable that the first embodiment of the lithium-based solid electrolyte of the present invention satisfies the following requirement T.

[0154] Requirement T: In the Raman spectrum of lithium-based solid electrolytes, at 710–730 cm⁻¹ -1 It has a peak and a half-peak width of 5cm. -1 The first peak mentioned above is between 770 and 790 cm. -1 It has a peak and a half-peak width of 5cm. -1 The second peak mentioned above is located at 1020–1040 cm⁻¹. -1 It has a peak and a half-peak width of 5cm. -1 The third peak mentioned above does not exist, or,

[0155] In the Raman spectrum described above, if at least one specific peak selected from the first peak, the second peak, and the third peak is present, the ratio of the intensity of the peak to the intensity of at least one specific peak calculated by the following intensity measurement method is 5.0 or less.

[0156] Intensity measurement method: The above Raman spectra are measured at 400–600 cm⁻¹. -1 The minimum Raman intensity M1 in the wavenumber region represents the Raman spectrum in the range of 1300–1500 cm⁻¹. -1 A straight line is obtained by connecting the points representing the minimum Raman intensity M2 in the wavenumber region. In the region from the wavenumber representing the minimum M1 to the wavenumber representing the minimum M2, the values ​​excluding 710–730 cm⁻¹ are calculated. -1 770~790cm -1 and 1020~1040cm -1 The average difference between the Raman intensity of the aforementioned straight line and the Raman intensity of the Raman spectrum at each wavenumber in regions outside the aforementioned region is calculated. The absolute value of the difference between the Raman intensity of the aforementioned peak and the Raman intensity of the aforementioned straight line at the wavenumber representing the peak of the aforementioned specific peak is calculated. The ratio of the absolute value of the aforementioned difference to the absolute value of the aforementioned average difference is taken as the intensity ratio.

[0157] The following is an explanation of the aforementioned requirement T.

[0158] First, in the Raman spectrum of lithium-based solid electrolytes, in the range of 710–730 cm⁻¹ -1 It has a apex and a half-peak width of 5cm. -1 The first peak mentioned above is between 770 and 790 cm. -1 It has a peak and a half-peak width of 5cm. -1 The second peak mentioned above is located at 1020–1040 cm⁻¹. -1 It has a peak and a half-peak width of 5cm. -1 If none of the above third peaks exist, then requirement T is satisfied.

[0159] Additionally, the half-peak width of a peak refers to the width (cm) at half the peak's height. -1 ).

[0160] Furthermore, if at least one specific peak selected from the first, second, and third peaks exists in the Raman spectrum of the lithium-based solid electrolyte, and the intensity ratio of at least one of the specific peaks calculated by the following intensity measurement method is 5.0 or less, then requirement T is also satisfied. Among all the specific peaks, the above-mentioned intensity ratio is preferably satisfied.

[0161] Below, in Figure 15 The method for strength measurement is explained in the text.

[0162] Figure 15 This is an example of a Raman spectrum of a lithium-based solid electrolyte, with the vertical axis representing Raman intensity and the horizontal axis representing Raman shift. Additionally, in Figure 15 To facilitate understanding, an example with a single peak is shown.

[0163] In the intensity measurement method, firstly, the 400–600 cm⁻¹ region representing the Raman spectrum of the lithium-based solid electrolyte is used. -1 The minimum Raman intensity M1 in the wavenumber region and the point representing the 1300–1500 cm⁻¹ of the above Raman spectrum. -1 A straight line is obtained by connecting the points where the Raman intensity minimum M2 is located in the wavenumber region. Specifically, as... Figure 15 As shown, connecting point P1, which represents the minimum value M1, and point P2, which represents the minimum value M2, yields a straight line represented by a dashed line.

[0164] Next, from the wavenumber representing the minimum value M1 ( Figure 15 The wavenumbers from W1 to M2 (where W1 represents the minimum value M2) are... Figure 15 In the region up to W2), calculate except for 710~730cm. -1 770~790cm -1 and 1020~1040cm -1 The average difference between the Raman intensity of the aforementioned straight line and the Raman intensity of the Raman spectrum at each wavenumber in the region outside the specified region (hereinafter also referred to as the "specific region"). Furthermore, the aforementioned average difference refers to the average difference calculated per 2 cm interval from W1 to W2 in the specified region. -1 The value is obtained by taking the absolute value of the difference between the Raman intensity of the straight line in each wavenumber and the Raman intensity of the Raman spectrum, and then taking the arithmetic mean of the absolute values ​​of the differences.

[0165] Next, the absolute value of the difference between the Raman intensity of the peak in the wavenumber representing the specific peak and the Raman intensity of the straight line is calculated, and the ratio of the absolute value of the difference to the average difference value is used as the intensity ratio. More specifically, as... Figure 15 As shown, calculate the absolute value (|S1-S2|) of the difference between the Raman intensity S1 of the peak at wavenumber W3 representing the peak and the Raman intensity S2 of the straight line at wavenumber W3, and confirm whether the absolute value of the obtained difference is less than 5.0 times the above average difference value.

[0166] Under the condition T mentioned above, it means that there is no crystal structure or almost no crystal structure in the lithium-based solid electrolyte, and it is in an amorphous state.

[0167] That is, the first to third peaks described in requirement Y are mainly peaks originating from the crystal structure of the lithium-based solid electrolyte (especially the crystal structure of lithium tetraborate). In the absence of these peaks, since the lithium-based solid electrolyte does not have a defined crystal structure and is in an amorphous state, it is presumed, as described above, that a hydrated layer with excellent ion conductivity is easily formed. Furthermore, even if at least one of the first to third peaks is present, if the intensity ratio of any one of the specific peaks present is below a defined value, it indicates that a crystal structure is almost non-existent in the lithium-based solid electrolyte, and as described above, it is presumed that a hydrated layer with excellent ion conductivity is easily formed. In addition, in lithium-based solid electrolytes, unlike peaks originating from a defined crystal structure such as the crystal structure of lithium tetraborate (as an example), peaks caused by other factors sometimes occur. Examples of other factors include peaks originating from impurities, which sometimes overlap with the first to third peaks described above. In the case of achieving an amorphous state that can be presumed to be able to form a hydrated layer with excellent ion conductivity, the first to third peaks are reduced in most cases. Assuming as described above, even if a peak based on other factors accidentally overlaps with any one of the first to third peaks and a large peak appears, there are specific peaks with an intensity ratio below a specified value. It can be said that the lithium-based solid electrolyte is in an amorphous state, and it can be presumed that a hydrated layer with excellent ion conductivity can be formed.

[0168] In the Raman spectrum of the aforementioned lithium-based solid electrolyte, it is more preferable that, if the first, second, and third peaks are all absent, or if a specific peak selected from the first, second, and third peaks is present, the intensity ratio of at least one of the specific peaks is 3.0 or less. More preferably, if the first, second, and third peaks are all absent, or if a specific peak selected from the first, second, and third peaks is present, the intensity ratio of at least one of the specific peaks is 2.0 or less; particularly preferably, the first, second, and third peaks are all absent.

[0169] In addition, Raman imaging is performed as a method for measuring Raman spectroscopy. Raman imaging refers to a microscopic spectroscopy method that combines microscopy techniques with Raman spectroscopy. Specifically, it is a method that detects the measurement light containing Raman scattered light by scanning an excitation light on a sample, and visualizes the distribution of components based on the intensity of the measurement light.

[0170] The Raman imaging measurement conditions were set as follows: 27°C, atmospheric conditions, excitation light of 532 nm, objective lens of 100x, point scanning mapping mode, 1 μm spacing, exposure time of 1 second per point, cumulative integration count of 1, and measurement range of 70 μm × 50 μm. However, the measurement range may sometimes be narrowed depending on the film thickness of the sample.

[0171] Furthermore, principal component analysis (PCA) was performed on the Raman spectral data to remove noise. Specifically, in the PCA process, components with an autocorrelation coefficient of 0.6 or higher were used to recombine the spectra.

[0172] Furthermore, from the viewpoint of further enhancing the effects of the present invention, the mass reduction rate when the first embodiment of the lithium-based solid electrolyte of the present invention is heated to 800°C is preferably 20 to 40% by mass. From the viewpoint of further enhancing the effects of the present invention, a mass reduction rate of 25 to 35% by mass is more preferable.

[0173] The mass reduction of the lithium-based solid electrolyte of the present invention during the above-described heating is considered to be due to the removal of water contained in the lithium-based solid electrolyte. As shown above, the mass reduction rate expressed as a specified amount indicates that the lithium-based solid electrolyte contains a specified amount of water, and it is believed that the conductivity of lithium ions is improved by the presence of this water.

[0174] During the above-mentioned heating treatment, heating is performed at a rate of 20°C / second within a range from 25°C to 800°C. Furthermore, a known differential thermal analysis (TG-DTA) apparatus can be used for the measurement.

[0175] The aforementioned mass reduction rate is calculated by {(mass at 25°C - mass at 800°C) / mass at 25°C} × 100.

[0176] Furthermore, in order to perform the above-mentioned heat treatment, the lithium-based solid electrolyte of the present invention was vacuum dried at 40°C for 2 hours, and then measured under atmospheric conditions.

[0177] The bulk modulus of the lithium-based solid electrolyte of the present invention is not particularly limited in the first embodiment, but from the viewpoint of better performance of the present invention, it is preferably 45 GPa or less, more preferably 40 GPa or less. The lower limit is not particularly limited, but 5 GPa or more is preferred.

[0178] The above-mentioned bulk modulus of elasticity was determined by ultrasonic attenuation method.

[0179] Specifically, firstly, a suspension of the first embodiment of the lithium-based solid electrolyte of the present invention is prepared by suspending it in pure water. The content of the first embodiment of the lithium-based solid electrolyte of the present invention in the suspension is set to 1.2% by mass relative to the total mass of the suspension. Next, the ultrasonic attenuation spectrum of the above suspension is measured, and the bulk modulus of the first embodiment of the lithium-based solid electrolyte of the present invention is determined from the fitting based on the scattering attenuation theory formula. In addition, the particle size distribution, density (2.3 g / ml), and Poisson's ratio (0.12) of the lithium-based solid electrolyte of the present invention are used when performing the above fitting.

[0180] Regarding the fitting based on the above scattering attenuation theory formula, the bulk modulus is calculated using equations (7), (12) and (13) recorded in Kohjiro Kubo et al., Ultrasonics 62 (2015) 186-194.

[0181] Furthermore, the particle size distribution of the first embodiment of the lithium-based solid electrolyte of the present invention was obtained by using a flow cytometry particle image analysis method to obtain a histogram (particle size distribution) of the particle size of the first embodiment of the lithium-based solid electrolyte of the present invention. The aforementioned particle size is equivalent to the equivalent circle diameter.

[0182] The median particle size (D50) of the lithium-based solid electrolyte of the present invention is not particularly limited in the first embodiment, but from the viewpoint of better performance of the present invention, it is preferably 0.01 to 20 μm, more preferably 0.1 to 2.0 μm.

[0183] The method for determining the median particle size (D50) described above involves obtaining a particle image using flow cytometry particle image analysis, calculating the particle size distribution of the first embodiment of the lithium-based solid electrolyte of the present invention, and analyzing the obtained distribution. Furthermore, the aforementioned particle size is equivalent to the equivalent circle diameter.

[0184] <<Second Implementation Method>>

[0185] The second embodiment of the lithium-based solid electrolyte of the present invention includes Li, B and O.

[0186] Furthermore, the second embodiment of the lithium-based solid electrolyte of the present invention further includes two or more specific elements selected from Group 4, Group 15, Group 16, Group 17 of the periodic table, Si, C, Sc, Y, and H. Additionally, from the viewpoint of superior performance of the present invention, the second embodiment of the lithium-based solid electrolyte of the present invention preferably includes two or more specific elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H, and N.

[0187] Examples of elements in Group 4 of the periodic table include Ti, Zr, Hr, and Rf.

[0188] Elements belonging to group 15 of the periodic table include N, P, As, Sb, Bi, and Mc.

[0189] Elements belonging to group 16 of the periodic table include O, S, Se, Te, Po, and Lv.

[0190] Elements belonging to group 17 of the periodic table include F, Cl, Br, I, At, and Ts.

[0191] In the second embodiment of the lithium-based solid electrolyte of the present invention, the specific elements included can be three or more types. From the viewpoint of further improving the effects of the present invention, it is preferable that the lithium-based solid electrolyte includes two to five types of specific elements, more preferably two to four types.

[0192] The second embodiment of the lithium-based solid electrolyte of the present invention preferably contains two or more specific elements selected from F, S, N, P and C, more preferably contains two or more specific elements selected from F, S, C and N, and even more preferably contains three specific elements: F, S and N.

[0193] As will be described later, in the second embodiment of manufacturing the lithium-based solid electrolyte of the present invention, lithium tetraborate is preferably used as a raw material. At this time, the lithium tetraborate used is generally a compound represented by Li₂B₄O₇, which is mainly composed of Li, B, and O; however, in the present invention, deviations from the above standard values ​​are permissible. More specifically, Li₂ is preferred as lithium tetraborate. 2+x B 4+ y O 7+z The compounds represented by (-0.3 < x < 0.3, -0.3 < y < 0.3, -0.3 < z < 0.3). That is, when the molar amount of B is set to 4.00 to represent the molar amount of Li, the preferred molar amount of Li is 1.58 to 2.49, and the molar amount of O is 6.23 to 7.89. In other words, when the molar amount of B is set to 4.00, the preferred relative value of the molar amount of Li is 1.58 to 2.49, and the molar amount of O is 6.23 to 7.89.

[0194] In the second embodiment of the lithium-based solid electrolyte of the present invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of Li, the molar amount of Li is 1.58 to 3.49. That is, when the molar content of B is set to 4.00, the relative value of the molar content of Li is 1.58 to 3.49.

[0195] From the viewpoint of achieving better results with the present invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of Li, the molar amount of Li is preferably 1.58 to 3.00, more preferably 1.90 to 3.00, and even more preferably 2.00 to 3.00.

[0196] In the second embodiment of the lithium-based solid electrolyte of the present invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of O, the molar amount of O is 6.23 to 25.00. That is, when the molar content of B is set to 4.00, the relative value of the molar content of O is 6.23 to 25.00.

[0197] From the viewpoint of achieving better results with the present invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of O, the molar amount of O is preferably 10.00 to 23.00.

[0198] In the second embodiment of the lithium-based solid electrolyte of the present invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of a specific element, the molar amount of each specific element is 0.001 to 10.00. That is, when the molar content of B is set to 4.00, the relative value of the molar content of each specific element is 0.001 to 10.00.

[0199] From the viewpoint of achieving better results with the present invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of a specific element, the molar amount of each specific element is preferably 0.001 to 6.0, more preferably 0.01 to 5.0.

[0200] As described above, in the second embodiment of the lithium-based solid electrolyte of the present invention, two or more specific elements are included. Therefore, for example, when the second embodiment of the lithium-based solid electrolyte of the present invention includes two specific elements—specific element A and specific element B, which is a different type of specific element A—and the molar amount of B in the lithium-based solid electrolyte is set to 4.00, the molar amounts of specific element A and specific element B are 0.001 to 10.00, respectively. Furthermore, for example, when the second embodiment of the lithium-based solid electrolyte of the present invention includes three specific elements—specific element A, specific element B, which is a different type of specific element A, and specific element C, which is a different type of specific element A and B—and the molar amount of B in the lithium-based solid electrolyte is set to 4.00, the molar amounts of specific element A, specific element B, and specific element C are 0.001 to 10.00, respectively.

[0201] In the second embodiment of the lithium-based solid electrolyte of the present invention, the contents of Li, B, and specific elements are determined by known elemental analysis. For example, Li and B are analyzed by ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry); one specific element, such as N, is analyzed by inert gas fusion analysis; and one specific element, such as F and S, is analyzed by combustion ion chromatography. Regarding O, the analytical masses of all elements except O can be added together and the result calculated as the difference from the total powder content. Furthermore, the method for calculating the content of each element is not limited to the above; the content of other elements can be estimated based on the analytical results of the content of one element, taking into account the structure of the compound used.

[0202] The molar amounts of Li, O, and specific elements are calculated by determining the content of each element based on elemental analysis, with the molar amount of B set to 4.00.

[0203] As one of the preferred embodiments of the lithium-based solid electrolyte of the present invention, a lithium-based solid electrolyte comprising Li, B, O, F, S and N is provided, wherein when the molar amount of B is 4.00, the molar amount of Li is 1.58 to 3.49 (preferably 1.58 to 3.00), the molar amount of O is 6.23 to 25.00, the molar amount of F is 0.001 to 10.00, the molar amount of S is 0.001 to 2.00, and the molar amount of N is 0.001 to 1.00.

[0204] The preferred range of the above molar ratio is as described above.

[0205] In addition, the second embodiment of the lithium-based solid electrolyte of the present invention may contain Li, B, O and other elements other than specific elements.

[0206] The manufacturing method of the second embodiment of the lithium-based solid electrolyte of the present invention will be described in detail later. The lithium-based solid electrolyte of the present invention is preferably manufactured by a manufacturing method accompanied by mechanical grinding. For example, it is speculated that by mechanically grinding the raw materials (e.g., lithium oxides containing Li and B) of the second embodiment of the lithium-based solid electrolyte of the present invention, the crystalline components in the raw materials can be amorphized, and as a result, a hydrated layer with excellent ion conductivity can be easily formed.

[0207] Furthermore, from the viewpoint of achieving superior effects, the second embodiment of the lithium-based solid electrolyte of the present invention was tested at 120°C. 7The full width at half maximum (FWHM) of the peaks with chemical shifts in the range of -100 to +100 ppm obtained during Li-NMR measurements is comparable to that of the solid lithium-based solid electrolyte of the second embodiment of the present invention, which was subjected to Li-NMR measurements at 20°C. 7 In Li-NMR measurements, the proportion of the full width at half maximum (FWHM) of peaks with chemical shifts in the range of -100 to +100 ppm is preferably 50% or less, more preferably 40% or less, and even more preferably 35% or less. There is no particular limitation on the lower limit, but it is usually 10% or more.

[0208] The full width at half peak (FWHM) refers to the width (ppm) at half the height (H) of the peak (H / 2).

[0209] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0210] Furthermore, from the viewpoint of achieving superior effects, the second embodiment of the lithium-based solid electrolyte of the present invention was tested at 20°C. 7 When performing waveform separation on the first peak appearing in the range of -100 to +100 ppm in the spectrum obtained during Li-NMR determination, it is preferable to have a second peak with a full width at half maximum (FWHM) of 5 ppm or less in the range of -3 to 3 ppm chemical shift, and the ratio of the area intensity of the second peak to the area intensity of the first peak is 0.5% or more. More preferably, this ratio is 2% or more, and even more preferably 15% or more. There is no particular upper limit to the ratio of the area intensity, but in most cases it is 50% or less.

[0211] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0212] Furthermore, from the viewpoint of achieving superior effects, in the infrared absorption spectrum of the second embodiment of the lithium-based solid electrolyte of the present invention, a range of 3000 to 3500 cm⁻¹ is preferred. -1 The maximum absorption intensity in the wavenumber region is relative to 800–1600 cm⁻¹ -1 The ratio of the maximum absorption intensity in the wavenumber region is 1 / 5 or more. From the viewpoint of further enhancing the effects of the present invention, the ratio is preferably 3 / 10 or more, more preferably 2 / 5 or more. There is no particular upper limit, but 1 or less is preferred.

[0213] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0214] Furthermore, from the viewpoint of achieving superior results, it is preferable to use Raman spectroscopy based on the 600–850 cm⁻¹ range in the second embodiment of the lithium-based solid electrolyte of the present invention.-1 The coefficient of determination obtained by least squares linear regression analysis within the wavenumber region is above 0.9400.

[0215] Furthermore, from the viewpoint of achieving better results with the present invention, the aforementioned coefficient of determination is more preferably 0.9600 or higher. There is no particular upper limit, but 1.0000 can be cited as an example.

[0216] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0217] Furthermore, from the viewpoint of achieving better results, the second embodiment of the lithium-based solid electrolyte of the present invention preferably satisfies requirement T.

[0218] The following requirement T is the same as the requirement T specified in the first embodiment described above, and its measurement method is also as described in the first embodiment.

[0219] Requirement T: In the Raman spectrum of lithium-based solid electrolytes, at 710–730 cm⁻¹ -1 It has a peak and a half-peak width of 5cm. -1 The first peak mentioned above is between 770 and 790 cm. -1 It has a peak and a half-peak width of 5cm. -1 The second peak mentioned above is located at 1020–1040 cm⁻¹. -1 It has a peak and a half-peak width of 5cm. -1 The third peak mentioned above does not exist, or,

[0220] In the Raman spectrum described above, if at least one specific peak selected from the first peak, the second peak, and the third peak is present, the ratio of the intensity of the peak to the intensity of at least one specific peak calculated by the following intensity measurement method is 5.0 or less.

[0221] Intensity measurement method: The above Raman spectra are measured at 400–600 cm⁻¹. -1 The minimum Raman intensity M1 in the wavenumber region represents the Raman spectrum in the range of 1300–1500 cm⁻¹. -1 A straight line is obtained by connecting the points representing the minimum Raman intensity M2 in the wavenumber region. In the region from the wavenumber representing the minimum M1 to the wavenumber representing the minimum M2, the values ​​excluding 710–730 cm⁻¹ are calculated. -1 770~790cm -1 and 1020~1040cm -1The average difference between the Raman intensity of the aforementioned straight line and the Raman intensity of the Raman spectrum at each wavenumber in regions outside the aforementioned region is calculated. The absolute value of the difference between the Raman intensity of the aforementioned peak and the Raman intensity of the aforementioned straight line at the wavenumber representing the peak of the aforementioned specific peak is calculated. The ratio of the absolute value of the aforementioned difference to the absolute value of the aforementioned average difference is taken as the intensity ratio.

[0222] In the Raman spectrum of the aforementioned lithium-based solid electrolyte, if peaks 1, 2, and 3 are absent, or if a specific peak selected from peaks 1, 2, and 3 is present, the intensity ratio of at least one of the specific peaks is more preferably 3.0 or less. Wherein, if peaks 1, 2, and 3 are absent, or if a specific peak selected from peaks 1, 2, and 3 is present, the intensity ratio of at least one of the specific peaks is further preferably 2.0 or less, and particularly preferably, peaks 1, 2, and 3 are absent.

[0223] Furthermore, from the viewpoint of achieving even better results from the present invention, it is preferable that the mass reduction rate when the second embodiment of the lithium-based solid electrolyte of the present invention is heated to 800°C is 20 to 40% by mass. From the viewpoint of achieving even better results from the present invention, a mass reduction rate of 25 to 35% by mass is more preferable.

[0224] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0225] The bulk modulus of the lithium-based solid electrolyte of the present invention is not particularly limited in the second embodiment, but from the viewpoint of better performance of the present invention, it is preferably 45 GPa or less, more preferably 40 GPa or less. The lower limit is not particularly limited, but 5 GPa or more is preferred.

[0226] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0227] The median particle size (D50) of the lithium-based solid electrolyte of the present invention is not particularly limited in the second embodiment, but from the viewpoint of better performance of the present invention, it is preferably 0.01 to 20 μm, more preferably 0.1 to 2.0 μm.

[0228] The method for determining the median particle size (D50) described above involves obtaining a particle image using flow cytometry particle image analysis, calculating the particle size distribution of the second embodiment of the lithium-based solid electrolyte of the present invention, and analyzing the obtained distribution. Furthermore, the aforementioned particle size is equivalent to the equivalent circle diameter.

[0229] From the viewpoint of achieving better results, the second embodiment of the lithium-based solid electrolyte of the present invention preferably satisfies the following requirement X. This requirement X is the same as the requirement X specified in the fourth embodiment described later, and will be described in detail thereafter.

[0230] Requirement X: In the reduced-dimer distribution function G(r) obtained from X-ray total scattering measurements of lithium-based solid electrolytes, there exists a peak located at r. The first peak and the apex within the range are located at r. The second peak within the range, the peak of the first peak has a G(r) greater than 1.0 (preferably 1.2 or more), and the peak of the second peak has a G(r) greater than 0.8 (preferably greater than 1.0).

[0231] From the viewpoint of achieving better results, the second embodiment of the lithium-based solid electrolyte of the present invention preferably satisfies the following requirement Y. This requirement Y is the same as the requirement Y specified in the fourth embodiment described later, and will be described in detail later.

[0232] Requirement Y: In the X-ray diffraction pattern obtained by using CuK α rays in the X-ray diffraction measurement of lithium-based solid electrolytes, the following peaks are absent: the first peak with a peak value of less than 0.65° in the range of 21.6–22.0°; the second peak with a peak value of less than 0.65° in the range of 25.4–25.8°; the third peak with a peak value of less than 0.65° in the range of 33.4–33.8°; and the fourth peak with a peak value of less than 0.65° in the range of 34.4–34.8°.

[0233] In an X-ray diffraction pattern, if there is at least one specific peak selected from the first, second, third, and fourth peaks, the intensity ratio of at least one of the specific peaks calculated by the following intensity measurement method is 5.0 or less.

[0234] Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak, and calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak. Calculate the arithmetic mean of the average intensity 1 and the average intensity 2. The ratio of the peak intensity in the peak of the specific peak to the arithmetic mean is set as the intensity ratio.

[0235] In the X-ray diffraction pattern obtained by using CuK α rays in the second embodiment of the lithium-based solid electrolyte described above, it is more preferable that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, and the intensity ratio of at least one of the specific peaks is 3.0 or less. More preferably, in the case that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, the intensity ratio of at least one of the specific peaks is 2.0 or less.

[0236] <<Third Implementation Method>>

[0237] The third embodiment of the lithium-based solid electrolyte of the present invention comprises lithium tetraborate, water, and lithium salt that have been mechanically ground.

[0238] The following is a detailed description of each component.

[0239] (Lithium tetraborate that has undergone mechanical grinding (hereinafter also referred to as "specific lithium tetraborate"))

[0240] The lithium tetraborate included in the third embodiment of the lithium-based solid electrolyte of the present invention has undergone mechanical grinding.

[0241] First, the lithium tetraborate included in the third embodiment is a compound typically represented by Li₂B₄O₇, which is mainly composed of Li, B, and O. However, in this invention, deviations from the aforementioned standard values ​​are permissible. More specifically, Li₂ is preferred as lithium tetraborate. 2+x B 4+y O 7+z The compounds represented by (-0.3 < x < 0.3, -0.3 < y < 0.3, -0.3 < z < 0.3).

[0242] As an example of mechanical grinding treatment performed on lithium tetraborate, the mechanical grinding treatment performed in step 1A described later can be cited as an example, and the details will be described in detail later.

[0243] It is speculated that lithium tetraborate can be amorphized by mechanical grinding, resulting in the easy formation of a hydrated layer with excellent ion conductivity.

[0244] From the viewpoint of achieving better results with the present invention, the specific lithium tetraborate preferably satisfies the following requirement W. That is, the specific lithium tetraborate preferably represents the lithium tetraborate with the characteristics expressed in requirement W.

[0245] Condition W: In the reduced-dibule distribution function G(r) obtained from the X-ray total scattering measurement of a specific lithium tetraborate, there exists a peak located at r. The first peak and the apex within the range are located at r. The G(r) of the second peak, the peak of the first peak, and the peak of the second peak within the range indicate that the value of G(r) is greater than 1.0, and r is greater than 1.0. Head. The absolute value of G(r) is less than 1.0 in the following range.

[0246] The following uses Figures 8-10 The requirement W is explained.

[0247] exist Figure 8The image shows an example of the reduced two-body distribution function G(r) obtained by X-ray total scattering measurement of a specific lithium tetraborate. Figure 8 The vertical axis is the reduced two-body distribution function obtained by performing a Fourier transform on X-ray scattering, representing the probability that an atom exists at a distance r.

[0248] In SPring-8 BL04B2 (accelerating voltage 61.4keV, wavelength) X-ray total scattering was measured under these conditions.

[0249] In addition, the scattering intensity I obtained through experiments was transformed by the following steps to obtain the reduced two-body distribution function G(r).

[0250] First, the scattering intensity I obs It is expressed by equation (1). Furthermore, the structure factor S(Q) is obtained by converting I... coh It is obtained by dividing by the product of the number of atoms N and the atomic scattering factor f.

[0251] I obs =I coh +I incoh +I 荧光 (1)

[0252] [Formula 2]

[0253]

[0254] PDF (Pair Distribution Function) analysis requires the use of the structure factor S(Q). In equation (2) above, the required intensity is only the coherent scattering I. coh Incoherent scattering I inooh and fluorescent X-ray I 荧光 It is possible to use blank measurements, theoretical formulas to subtract, and the detector's discriminator to obtain the scattering intensity I. obs Subtract from the middle. An example of the total scattering measurement results and extracted structure factor S(Q) of a specific lithium tetraborate is shown in the figure. Figure 9 and Figure 10 middle.

[0255] Coherent scattering is represented by Debye's scattering equation (3) (N: total number of atoms, f: atomic scattering factor, r ij (The interatomic distance between ij).

[0256] [Formula 3]

[0257]

[0258] If we focus on any atom and define the atomic density at a distance r as ρ(r), then the number of atoms existing within a sphere of radius r-r+d(r) becomes 4πr. 2 ρ(r)dr, therefore equation (3) can be expressed by equation (4).

[0259] [Formula 4]

[0260]

[0261] If we set the average density of atoms as ρ0, and transform equation (4), we can obtain equation (5).

[0262] [Formula 5]

[0263]

[0264] Equation (6) can be obtained from equations (5) and (2).

[0265] [Formula 6]

[0266]

[0267] The two-body distribution function g(r) is represented by equation (7).

[0268] [Formula 7]

[0269]

[0270] Equation (8) can be obtained from equations (6) and (7) above.

[0271] [Formula 8]

[0272]

[0273] As mentioned above, the two-body distribution function can be obtained through the Fourier transform of the structure factor S(Q). To facilitate the observation of order over medium / long distances, the two-body distribution function is transformed into G(r) = 4πr(g(r)-1), which is the reconstructed two-body distribution function. Figure 8 The g(r) oscillating around 0 represents the density difference between the interatomic distances and the average density. When there is correlation at specific interatomic distances, the average density is higher than 1. Therefore, it reflects the distance and coordination number of elements corresponding to local to intermediate distances. If order is lost, ρ(r) approaches the average density, and thus g(r) gradually approaches 1. Therefore, since in amorphous structures, the larger r becomes, the more disordered it becomes, and thus g(r) becomes 1, i.e., G(r) becomes 0.

[0274] In requirement W, such as Figure 8As shown, in the reduced two-body distribution function G(r) obtained from X-ray total scattering measurements, there exists a peak located at r. The first peak P1 and the apex within the range are located at r. The G(r) of the peak of the second peak P2, the peak of the first peak P1, and the peak of the second peak P2 within the range are greater than 1.0.

[0275] That is, in the reduced two-body distribution function G(r) obtained from X-ray total scattering measurements of a specific lithium tetraborate, the G(r) with a peak (hereinafter also referred to as the "first peak") indicates that the G(r) is greater than 1.0, and the first peak indicates that it is located at... The G(r) of the first peak and the apex (hereinafter also referred to as the "second apex") in the range is greater than 1.0, and the second apex is located at... The second peak in the range.

[0276] In addition, Figure 8 In the middle, the peak of the first peak P1 is located at The peak of the second peak, P2, is located at

[0277] exist The position contains a peak at which the interatomic distance between B (boron) and O (oxygen) is located. Furthermore, in The position of the peak belongs to the interatomic distance of B(boron)-B(boron). That is, the observation of the above two peaks (the first peak and the second peak) means that the periodic structure corresponding to the above two interatomic distances exists in a specific lithium tetraborate.

[0278] Furthermore, in requirement W, such as Figure 8 As shown, when r is greater than and In the following range, the absolute value of G(r) is less than 1.0 (equivalent to the dashed line).

[0279] As mentioned above, when r is greater than and In the following range, an absolute value of G(r) less than 1.0 indicates that long-distance ordered structures are almost non-existent in a particular lithium tetraborate.

[0280] As described above, a specific lithium tetraborate that satisfies the aforementioned condition W has a short-range ordered structure related to the interatomic distances of BO and BB, but almost no long-range ordered structure. Therefore, this specific lithium tetraborate inherently exhibits elastic properties that allow for easy plastic deformation.

[0281] Furthermore, in the aforementioned reduced two-body distribution function G(r), when r is... The following ranges may contain peaks other than the first and second peaks.

[0282] Furthermore, from the viewpoint of achieving better results with the present invention, the specific lithium tetraborate preferably satisfies the following requirement V. That is, the specific lithium tetraborate preferably represents lithium tetraborate with the characteristics represented by requirement V.

[0283] In addition, except that a specific lithium tetraborate is used as the object of measurement for requirement Y in the fourth embodiment described later, requirement V is evaluated using the same steps, and the evaluation method is represented by requirement Y described later.

[0284] Requirement V: In the X-ray diffraction pattern obtained by using CuK α rays in a specific lithium tetraborate X-ray diffraction measurement, the following peaks are absent: the first peak with a peak value of less than 0.65° in the range of 21.6–22.0°; the second peak with a peak value of less than 0.65° in the range of 25.4–25.8°; the third peak with a peak value of less than 0.65° in the range of 33.4–33.8°; and the fourth peak with a peak value of less than 0.65° in the range of 34.4–34.8°.

[0285] In an X-ray diffraction pattern, if there is at least one specific peak selected from the first, second, third, and fourth peaks, the intensity ratio of at least one of the specific peaks calculated by the following intensity measurement method is 5.0 or less.

[0286] Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak, and calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak. Calculate the arithmetic mean of the average intensity 1 and the average intensity 2. The ratio of the peak intensity in the peak of the specific peak to the arithmetic mean is set as the intensity ratio.

[0287] In the X-ray diffraction pattern obtained by X-ray diffraction measurement of a specific lithium tetraborate using CuK α rays, it is more preferable that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, and the intensity ratio of at least one of the specific peaks is 3.0 or less. More preferably, in the case that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, the intensity ratio of at least one of the specific peaks is 2.0 or less.

[0288] In addition, if there are two or more peaks in the X-ray diffraction pattern of requirement V that are located in the range of 21.6 to 22.0° and have a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest diffraction X-ray intensity is selected as the first peak for determining requirement V.

[0289] Furthermore, in the X-ray diffraction pattern of requirement V, if there are two or more peaks with a peak value in the range of 25.4 to 25.8° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest diffraction X-ray intensity is selected as the second peak for determining requirement V.

[0290] Furthermore, in the X-ray diffraction pattern of requirement V, if there are two or more peaks with a peak value in the range of 33.4 to 33.8° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest diffraction X-ray intensity is selected as the third peak for determining requirement V.

[0291] Furthermore, in the X-ray diffraction pattern of requirement V, if the peak is located in the range of 34.4 to 34.8° and there are more than two peaks with a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the fourth peak for determining requirement V.

[0292] Furthermore, from the viewpoint of achieving better results with the present invention, a particular lithium tetraborate preferably satisfies the following requirement T2.

[0293] Regarding the following requirement T2, except that a specific lithium tetraborate is used as the object of measurement for requirement T in the first embodiment described above, and the requirement is evaluated by the same steps, the evaluation method of which is as described above.

[0294] Requirement T2: In the Raman spectrum of a specific lithium tetraborate, it has a wavelength between 710 and 730 cm⁻¹. -1 It has a peak and a half-peak width of 5cm. -1 The first peak mentioned above is between 770 and 790 cm. -1 It has a peak and a full width of 5cm at half the peak. -1 The second peak mentioned above is located at 1020–1040 cm⁻¹. -1 It has a peak and a half-peak width of 5cm -1 The third peak mentioned above does not exist, or

[0295] In the Raman spectrum described above, if at least one specific peak selected from the first peak, the second peak, and the third peak is present, the ratio of the intensity of the peak to the intensity of at least one specific peak calculated by the following intensity measurement method is 5.0 or less.

[0296] Intensity measurement method: The above Raman spectra are measured at 400–600 cm⁻¹. -1 The minimum Raman intensity M1 in the wavenumber region represents the Raman spectrum in the range of 1300–1500 cm⁻¹. -1A straight line is obtained by connecting the points representing the minimum Raman intensity M2 in the wavenumber region. In the region from the wavenumber representing the minimum M1 to the wavenumber representing the minimum M2, the values ​​excluding 710–730 cm⁻¹ are calculated. -1 770~790cm -1 and 1020~1040em -1 The average difference between the Raman intensity of the aforementioned straight line and the Raman intensity of the Raman spectrum at each wavenumber in regions outside the aforementioned region is calculated. The absolute value of the difference between the Raman intensity of the aforementioned peak and the Raman intensity of the aforementioned straight line at the wavenumber representing the peak of the aforementioned specific peak is calculated. The ratio of the absolute value of the aforementioned difference to the absolute value of the aforementioned average difference is taken as the intensity ratio.

[0297] In the Raman spectrum of the aforementioned specific lithium tetraborate, it is more preferable that peaks 1, 2, and 3 are all absent, or that a specific peak selected from peaks 1, 2, and 3 is present, wherein the intensity ratio of at least one of the specific peaks is 3.0 or less. Wherein, when peaks 1, 2, and 3 are all absent, or that a specific peak selected from peaks 1, 2, and 3 is present, the intensity ratio of at least one of the specific peaks is further preferably 2.0 or less, and particularly preferably that peaks 1, 2, and 3 are all absent.

[0298] The content of a specific lithium tetraborate in the third embodiment of the lithium-based solid electrolyte of the present invention is not particularly limited.

[0299] (water)

[0300] The third embodiment of the lithium-based solid electrolyte of the present invention includes water.

[0301] The water content in the third embodiment of the lithium-based solid electrolyte of the present invention is not particularly limited. However, from the viewpoint of better performance of the present invention, the molar ratio of water to a specific lithium tetraborate (molar amount of water / molar amount of a specific lithium tetraborate) in the third embodiment of the lithium-based solid electrolyte of the present invention is preferably 3 to 15, more preferably 4 to 13, further preferably 5 to 13, and particularly preferably 10 to 13.

[0302] (Lithium salt)

[0303] The third embodiment of the lithium-based solid electrolyte of the present invention includes a lithium salt.

[0304] There are no particular restrictions on the types of lithium salts. Examples of lithium salts shown in step 1A described later will be given in detail in the following section.

[0305] The lithium salt content in the third embodiment of the lithium-based solid electrolyte of the present invention is not particularly limited.

[0306] In the third embodiment of the lithium-based solid electrolyte of the present invention, the mass ratio of lithium salt content to the specific lithium tetraborate content (mass of lithium salt content / mass of specific lithium tetraborate content) is not particularly limited. However, from the viewpoint of better effects of the present invention, the molar ratio of lithium salt to specific lithium tetraborate (molar amount of lithium salt / molar amount of specific lithium tetraborate) in the third embodiment of the lithium-based solid electrolyte of the present invention is preferably 0.001 to 1.5, more preferably 0.001 to 1.2, further preferably 0.01 to 1.2, particularly preferably 0.1 to 1.2, and most preferably 0.5 to 1.2.

[0307] Furthermore, the molar ratios of the components in the third embodiment of the lithium-based solid electrolyte of the present invention can be determined using known methods. For example, elemental analysis described in the first embodiment above can be used.

[0308] Furthermore, from the viewpoint of achieving even better results from the present invention, the third embodiment of the lithium-based solid electrolyte of the present invention was tested at 120°C. 7 The full width at half maximum (FWHM) of the peaks with chemical shifts in the range of -100 to +100 ppm obtained during Li-NMR measurements is comparable to that of the solid lithium-based solid electrolyte of the third embodiment of the present invention, which was subjected to testing at 20°C. 7 In Li-NMR measurements, the proportion of the full width at half maximum (FWHM) of peaks with chemical shifts in the range of -100 to +100 ppm is preferably 50% or less, more preferably 40% or less, and even more preferably 35% or less. There is no particular limitation on the lower limit, but it is usually 10% or more.

[0309] The full width at half peak (FWHM) refers to the width (ppm) at half the height (H) of the peak (H / 2).

[0310] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0311] Furthermore, from the viewpoint of achieving superior effects, the third embodiment of the lithium-based solid electrolyte of the present invention was tested at 20°C. 7 When performing waveform separation on the first peak appearing in the range of -100 to +100 ppm in the spectrum obtained during Li-NMR determination, it is preferable to have a second peak with a full width at half maximum (FWHM) of 5 ppm or less in the range of -3 to 3 ppm chemical shift, and the ratio of the area intensity of the second peak to the area intensity of the first peak is 0.5% or more. More preferably, this ratio is 2% or more, and even more preferably 15% or more. There is no particular upper limit to the ratio of the area intensity, but in most cases it is 50% or less.

[0312] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0313] Furthermore, from the viewpoint of achieving superior effects, in the infrared absorption spectrum of the third embodiment of the lithium-based solid electrolyte of the present invention, a range of 3000 to 3500 cm⁻¹ is preferred. -1 The maximum absorption intensity in the wavenumber region is relative to 800–1600 cm⁻¹ -1 The ratio of the maximum absorption intensity in the wavenumber region is 1 / 5 or more. From the viewpoint of further enhancing the effects of the present invention, the ratio is preferably 3 / 10 or more, more preferably 2 / 5 or more. There is no particular upper limit, but 1 or less is preferred.

[0314] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0315] Furthermore, from the viewpoint of achieving superior results, the third embodiment of the lithium-based solid electrolyte of the present invention, based on Raman spectroscopy at 600–850 cm⁻¹, demonstrates even better performance. -1 The coefficient of determination obtained by least squares linear regression analysis within the wavenumber region is preferably above 0.9400.

[0316] Furthermore, from the viewpoint of achieving better results with the present invention, the aforementioned coefficient of determination is more preferably 0.9600 or higher. There is no particular upper limit, but 1.0000 can be cited as an example.

[0317] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0318] Furthermore, from the viewpoint of achieving better results, the third embodiment of the lithium-based solid electrolyte of the present invention preferably satisfies requirement T.

[0319] The following requirement T is the same as the requirement T specified in the first embodiment described above, and its measurement method is also as described in the first embodiment.

[0320] Requirement T: In the Raman spectrum of lithium-based solid electrolytes, at 710–730 cm⁻¹ -1 It has a peak and a half-peak width of 5cm. -1 The first peak mentioned above is between 770 and 790 cm. -1 It has a peak and a half-peak width of 5cm. -1 The second peak mentioned above is located at 1020–1040 cm⁻¹. -1 It has a peak and a half-peak width of 5cm. -1 The third peak mentioned above does not exist, or,

[0321] In the Raman spectrum described above, if at least one specific peak selected from the first peak, the second peak, and the third peak is present, the ratio of the intensity of the peak to the intensity of at least one specific peak calculated by the following intensity measurement method is 5.0 or less.

[0322] Intensity measurement method: The above Raman spectra are measured at 400–600 cm⁻¹. -1 The minimum Raman intensity M1 in the wavenumber region represents the Raman spectrum in the range of 1300–1500 cm⁻¹. -1 A straight line is obtained by connecting the points representing the minimum Raman intensity M2 in the wavenumber region. In the region from the wavenumber representing the minimum M1 to the wavenumber representing the minimum M2, the values ​​excluding 710–730 cm⁻¹ are calculated. -1 770~790cm -1 and 1020~1040cm -1 The average difference between the Raman intensity of the aforementioned straight line and the Raman intensity of the Raman spectrum at each wavenumber in regions outside the aforementioned region is calculated. The absolute value of the difference between the Raman intensity of the aforementioned peak and the Raman intensity of the aforementioned straight line at the wavenumber representing the peak of the aforementioned specific peak is calculated. The ratio of the absolute value of the aforementioned difference to the absolute value of the aforementioned average difference is taken as the intensity ratio.

[0323] In the Raman spectrum of the aforementioned lithium-based solid electrolyte, if peaks 1, 2, and 3 are absent, or if a specific peak selected from peaks 1, 2, and 3 is present, the intensity ratio of at least one of the specific peaks is more preferably 3.0 or less. Wherein, if peaks 1, 2, and 3 are absent, or if a specific peak selected from peaks 1, 2, and 3 is present, the intensity ratio of at least one of the specific peaks is further preferably 2.0 or less, and particularly preferably, peaks 1, 2, and 3 are absent.

[0324] Furthermore, from the viewpoint of achieving even better results from the present invention, the mass reduction rate when the lithium-based solid electrolyte of the third embodiment of the present invention is heated to 800°C is preferably 20 to 40% by mass. From the viewpoint of achieving even better results from the present invention, a mass reduction rate of 25 to 35% by mass is more preferable.

[0325] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0326] The bulk modulus of the lithium-based solid electrolyte of the present invention is not particularly limited in the third embodiment, but from the viewpoint of better performance of the present invention, it is preferably 45 GPa or less, more preferably 40 GPa or less. The lower limit is not particularly limited, but 5 GPa or more is preferred.

[0327] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0328] Furthermore, the preferred range of the bulk elastic modulus of a specific lithium tetraborate is the same as the preferred range of the bulk elastic modulus of the third embodiment of the lithium-based solid electrolyte of the present invention described above.

[0329] The median particle size (D50) of the lithium-based solid electrolyte of the present invention in the third embodiment is not particularly limited, but from the viewpoint of better performance of the present invention, it is preferably 0.01 to 20 μm, more preferably 0.1 to 2.0 μm.

[0330] The method for determining the median particle size (D50) described above involves obtaining a particle image using flow cytometry particle image analysis, calculating the particle size distribution of the third embodiment of the lithium-based solid electrolyte of the present invention, and analyzing the obtained distribution. Furthermore, the aforementioned particle size is equivalent to the diameter of an equivalent circle.

[0331] From the viewpoint of achieving better results, the third embodiment of the lithium-based solid electrolyte of the present invention preferably satisfies the following requirement X. This requirement X is the same as the requirement X specified in the fourth embodiment described later, and will be described in detail thereafter.

[0332] Requirement X: In the reduced-dimer distribution function G(r) obtained from X-ray total scattering measurements of lithium-based solid electrolytes, there exists a peak located at r. The first peak and the apex within the range are located at r. The second peak within the range, the peak of the first peak has a G(r) greater than 1.0 (preferably 1.2 or more), and the peak of the second peak has a G(r) greater than 0.8 (preferably greater than 1.0).

[0333] From the viewpoint of achieving better results, the third embodiment of the lithium-based solid electrolyte of the present invention preferably satisfies the following requirement Y. This requirement Y is the same as the requirement Y specified in the fourth embodiment described later, and will be described in detail later.

[0334] Requirement Y: In the X-ray diffraction pattern obtained by using CuK α rays in the X-ray diffraction measurement of lithium-based solid electrolytes, the following peaks are absent: the first peak with a peak value of less than 0.65° in the range of 21.6–22.0°; the second peak with a peak value of less than 0.65° in the range of 25.4–25.8°; the third peak with a peak value of less than 0.65° in the range of 33.4–33.8°; and the fourth peak with a peak value of less than 0.65° in the range of 34.4–34.8°.

[0335] In an X-ray diffraction pattern, if there is at least one specific peak selected from the first, second, third, and fourth peaks, the intensity ratio of at least one of the specific peaks calculated by the following intensity measurement method is 5.0 or less.

[0336] Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak, and calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak. Calculate the arithmetic mean of the average intensity 1 and the average intensity 2. The ratio of the peak intensity in the peak of the specific peak to the arithmetic mean is set as the intensity ratio.

[0337] In the X-ray diffraction pattern obtained by using CuK α rays in the third embodiment of the lithium-based solid electrolyte described above, it is more preferable that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, and the intensity ratio of at least one of the specific peaks is 3.0 or less. More preferably, in the case that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, the intensity ratio of at least one of the specific peaks is 2.0 or less.

[0338] (Another way)

[0339] Furthermore, in the above description of the third embodiment, the method of using a specific lithium tetraborate was described. In the third embodiment, amorphous lithium tetraborate can be used instead of the specific lithium tetraborate. That is, in the third embodiment of the lithium-based solid electrolyte of the present invention, it can be a mixture of amorphous lithium tetraborate, water, and lithium salt.

[0340] Amorphous lithium tetraborate refers to lithium tetraborate that satisfies at least one of requirements S1 to S3.

[0341] Regarding requirement S1, except that amorphous lithium tetraborate is used as the test object, it is evaluated by the same steps as requirement W described above, and the evaluation method is as described above.

[0342] Furthermore, regarding requirement S2, except that amorphous lithium tetraborate is used as the test object, it is an requirement evaluated through the same steps as requirement T described above, and the evaluation method is as described above.

[0343] Furthermore, regarding requirement S3, except that amorphous lithium tetraborate is used as the test object, it is evaluated by the same steps as requirement Y of the fourth embodiment described later, and the evaluation method is shown in requirement Y described later.

[0344] Requirement S1: In the reduced-dibule distribution function G(r) obtained from the X-ray total scattering measurement of amorphous lithium tetraborate, there exists a peak located at r. The first peak and the apex within the range are located at r. Within the range of the peak, the second peak, the peak of the first peak, and the peak of the second peak are all represented by G(r) greater than 1.0, where r is greater than 1.0. and The absolute value of G(r) is less than 1.0 in the following range.

[0345] Requirement S2: In the Raman spectrum of lithium tetraborate in its amorphous state, at 710–730 cm⁻¹ -1 It has a peak and a half-peak width of 5cm. -1 The first peak mentioned above is between 770 and 790 cm. -1 It has a peak and a half-peak width of 5cm. -1 The second peak mentioned above is located at 1020–1040 cm⁻¹. -1 It has a peak and a half-peak width of 5cm. -1 The third peak mentioned above does not exist, or

[0346] In the Raman spectrum described above, if at least one specific peak selected from the first peak, the second peak, and the third peak is present, the ratio of the intensity of the peak to the intensity of at least one specific peak calculated by the following intensity measurement method is 5.0 or less.

[0347] Intensity measurement method: The above Raman spectra are measured at 400–600 cm⁻¹. -1 The minimum Raman intensity M1 in the wavenumber region represents the Raman spectrum in the range of 1300–1500 cm⁻¹. -1 A straight line is obtained by connecting the points representing the minimum Raman intensity M2 in the wavenumber region. In the region from the wavenumber representing the minimum M1 to the wavenumber representing the minimum M2, the values ​​excluding 710–730 cm⁻¹ are calculated. -1 770~790cm -1 and 1020~1040cm -1 The average difference between the Raman intensity of the aforementioned straight line and the Raman intensity of the Raman spectrum at each wavenumber in regions outside the aforementioned region is calculated. The absolute value of the difference between the Raman intensity of the aforementioned peak and the Raman intensity of the aforementioned straight line at the wavenumber representing the peak of the aforementioned specific peak is calculated. The ratio of the absolute value of the aforementioned difference to the absolute value of the aforementioned average difference is taken as the intensity ratio.

[0348] Requirement S3: In the X-ray diffraction pattern obtained by CuK α-ray diffraction of amorphous lithium tetraborate, the following peaks are absent: the first peak with a peak value of less than 0.65° in the range of 21.6–22.0°; the second peak with a peak value of less than 0.65° in the range of 25.4–25.8°; the third peak with a peak value of less than 0.65° in the range of 33.4–33.8°; and the fourth peak with a peak value of less than 0.65° in the range of 34.4–34.8°.

[0349] In an X-ray diffraction pattern, if there is at least one specific peak selected from the first, second, third, and fourth peaks, the intensity ratio of at least one of the specific peaks calculated by the following intensity measurement method is 5.0 or less.

[0350] Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak, and calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak. Calculate the arithmetic mean of the average intensity 1 and the average intensity 2. The ratio of the peak intensity in the peak of the specific peak to the arithmetic mean is set as the intensity ratio.

[0351] In the Raman spectrum of lithium tetraborate in the amorphous state described in requirement S2, it is more preferable that peaks 1, 2, and 3 are all absent, or that a specific peak selected from peaks 1, 2, and 3 is present, wherein the intensity ratio of at least one of the specific peaks is 3.0 or less. Wherein, when peaks 1, 2, and 3 are all absent, or when a specific peak selected from peaks 1, 2, and 3 is present, the intensity ratio of at least one of the specific peaks is further preferably 2.0 or less, and particularly preferably that peaks 1, 2, and 3 are all absent.

[0352] In the X-ray diffraction pattern obtained by X-ray diffraction measurement of the specific lithium tetraborate using CuK α rays in the above-mentioned requirement S3, it is more preferable that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, and the intensity ratio of at least one of the specific peaks is 3.0 or less. More preferably, in the case that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, the intensity ratio of at least one of the specific peaks is 2.0 or less.

[0353] Furthermore, in the X-ray diffraction pattern of requirement S3, if there are two or more peaks located in the range of 21.6 to 22.0° and with a full width at half maximum (FWHM) of less than 0.65°, the peak with the highest X-ray diffraction intensity is selected as the first peak, and requirement S3 is determined.

[0354] Furthermore, in the X-ray diffraction pattern of requirement S3, if there are two or more peaks located in the range of 25.4 to 25.8° and with a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest diffraction X-ray intensity is selected as the second peak, and requirement S3 is determined.

[0355] Furthermore, in the X-ray diffraction pattern of requirement S3, if there are two or more peaks located in the range of 33.4 to 33.8° and with a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest diffraction X-ray intensity is selected as the third peak, and requirement S3 is determined.

[0356] Furthermore, in the X-ray diffraction pattern of requirement S3, if there are two or more peaks located in the range of 34.4 to 34.8° and with a full width at half maximum (FWHM) of less than 0.65°, the peak with the highest X-ray diffraction intensity is selected as the fourth peak, and requirement S3 is determined.

[0357] Furthermore, in lithium-based solid electrolytes comprising amorphous lithium tetraborate, water, and lithium salt, the relationship between the content of amorphous lithium tetraborate and other components (e.g., water and lithium salt) satisfies the same content relationship as when the specific lithium tetraborate described above is used. That is, the molar ratio of lithium salt to amorphous lithium tetraborate is preferably 0.001 to 1.5, and the molar ratio of water to amorphous lithium tetraborate is preferably 3 to 15. The preferred ranges for these molar ratios are the same as the preferred ranges for the molar ratio of lithium salt to the specific lithium tetraborate described above and the preferred ranges for the molar ratio of water to amorphous lithium tetraborate.

[0358] Furthermore, the lithium-based solid electrolyte comprising amorphous lithium tetraborate, water, and lithium salt preferably exhibits the various characteristics described in the third embodiment using the specific lithium tetraborate described above. Specifically, the following items can be cited as examples of these various characteristics, and their preferred ranges are as described above.

[0359] • Solid-state lithium-based solid electrolyte was tested at 120°C. 7 The full width at half maximum (FWHM) of the peaks with chemical shifts in the range of -100 to +100 ppm obtained during Li-NMR measurements is comparable to that of the solid lithium electrolyte obtained at 20 °C. 7The proportion of the full width at half maximum (FWHM) of peaks with chemical shifts in the range of -100 to +100 ppm obtained during Li-NMR measurements.

[0360] • Solid lithium-based solid electrolyte was tested at 20°C. 7 When the first peak in the spectrum obtained during Li-NMR determination appears in the range of -100 to +100 ppm, waveform separation is performed. A second peak with a full width at half maximum (FWHM) of less than 5 ppm exists in the range of -3 to 3 ppm. The ratio of the area intensity of the second peak to the area intensity of the first peak is...

[0361] • In the infrared absorption spectrum of lithium-based solid electrolytes, 3000–3500 cm⁻¹ -1 The maximum absorption intensity in the wavenumber region is relative to 800–1600 cm⁻¹ -1 The ratio of the maximum absorption intensity in the wavenumber region

[0362] • In the Raman spectra of lithium-based solid electrolytes, from 600 to 850 cm⁻¹ -1 The coefficients of determination obtained by linear regression analysis based on the least squares method within the wavenumber region

[0363] • Mass reduction rate of lithium-based solid electrolytes when heated to 800°C

[0364] • Bulk elastic modulus of lithium-based solid electrolytes

[0365] Median particle size (D50) of lithium-based solid electrolytes

[0366] Furthermore, the lithium-based solid electrolyte comprising amorphous lithium tetraborate, water, and lithium salt preferably satisfies at least one of requirements X, Y, and T, just as the lithium-based solid electrolyte comprising the specific lithium tetraborate described above.

[0367] Furthermore, in the X-ray diffraction pattern obtained by X-ray diffraction measurement using CuK α rays in the lithium-based solid electrolyte containing the aforementioned amorphous lithium tetraborate, which satisfies requirement Y, it is more preferable that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, and the intensity ratio of at least one of the specific peaks is 3.0 or less. More preferably, in the case that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, the intensity ratio of at least one of the specific peaks is 2.0 or less.

[0368] Furthermore, in the Raman spectrum of the lithium-based solid electrolyte containing the aforementioned amorphous lithium tetraborate, which satisfies requirement T, it is more preferable that the first, second, and third peaks are all absent, or that a specific peak selected from the first, second, and third peaks is present, and the intensity ratio of at least one of the specific peaks is 3.0 or less. Wherein, when the first, second, and third peaks are all absent, or when a specific peak selected from the first, second, and third peaks is present, the intensity ratio of at least one of the specific peaks is further preferably 2.0 or less, and particularly preferably that the first, second, and third peaks are all absent.

[0369] <<Implementation Method 4>>

[0370] The fourth embodiment of the lithium-based solid electrolyte of the present invention includes Li, B and O, satisfying any one of requirements X to Z.

[0371] The following is a detailed description of elements X to Z.

[0372] The fourth embodiment of the lithium-based solid electrolyte of the present invention satisfies the following requirement X.

[0373] Requirement X: In the reduced-dimer distribution function G(r) obtained from X-ray total scattering measurements of lithium-based solid electrolytes, there exists a peak located at r. The first peak and the apex within the range are located at r. The second peak within the range, the peak of the first peak has a G(r) greater than 1.0 (preferably 1.2 or more), and the peak of the second peak has a G(r) greater than 0.8 (preferably greater than 1.0).

[0374] Requirement X represents a portion of requirement W mentioned above. Its technical meaning is as described above, referring to the existence of a periodic structure corresponding to the interatomic distances of B (boron)-O (oxygen) and B (boron)-B (boron) in a lithium-based solid electrolyte.

[0375] Furthermore, in requirement X, the peak G(r) of the second peak is 0.8 or higher, which differs from requirement W. In requirement X, as described above, the peak G(r) of the first peak is preferably 1.2 or higher, and the peak G(r) of the second peak is preferably greater than 1.0.

[0376] The determination method for requirement X is the same as that for requirement W described above.

[0377] In addition, Figure 16 The figure shows an example of the reduced binary distribution function G(r) obtained from X-ray total scattering measurements of the fourth embodiment of the lithium-based solid electrolyte of the present invention.

[0378] The fourth embodiment of the lithium-based solid electrolyte of the present invention satisfies the following requirement Y.

[0379] Requirement Y: In the X-ray diffraction pattern obtained by using CuK α rays in the X-ray diffraction measurement of lithium-based solid electrolytes, the following peaks are absent: the first peak with a peak value of less than 0.65° in the range of 21.6–22.0°; the second peak with a peak value of less than 0.65° in the range of 25.4–25.8°; the third peak with a peak value of less than 0.65° in the range of 33.4–33.8°; and the fourth peak with a peak value of less than 0.65° in the range of 34.4–34.8°.

[0380] In an X-ray diffraction pattern, if there is at least one specific peak selected from the first, second, third, and fourth peaks, the intensity ratio of at least one of the specific peaks calculated by the following intensity measurement method is 5.0 or less.

[0381] Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak, and calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak. Calculate the arithmetic mean of the average intensity 1 and the average intensity 2. The ratio of the peak intensity in the peak of the specific peak to the arithmetic mean is set as the intensity ratio.

[0382] The following is an explanation of requirement Y.

[0383] First, in the X-ray diffraction pattern obtained by using CuK α rays in the X-ray diffraction measurement of lithium-based solid electrolytes, if the following conditions are not met: the first peak with a peak value in the range of 21.6–22.0° and a full width at half maximum (FWHM) of less than 0.65°; the second peak with a peak value in the range of 25.4–25.8° and a FWHM of less than 0.65°; the third peak with a peak value in the range of 33.4–33.8° and a FWHM of less than 0.65°; and the fourth peak with a peak value in the range of 34.4–34.8° and a FWHM of less than 0.65°, then condition Y is met.

[0384] The full width at half maximum (FWHM) of a peak refers to the width (°) at half the intensity of the peak.

[0385] Furthermore, if the X-ray diffraction pattern obtained in the X-ray diffraction measurement using CuK α rays of the lithium-based solid electrolyte contains at least one specific peak selected from the first, second, third, and fourth peaks, and the intensity ratio calculated by the intensity measurement method described later for at least one of the specific peaks is 5.0 or less, then requirement Y is also satisfied.

[0386] The following describes the methods for strength testing. Figure 11Please provide an explanation.

[0387] Figure 11 This is a diagram illustrating an example of a specific peak appearing in the diffraction pattern obtained using CuK α rays in X-ray diffraction measurements of a lithium-based solid electrolyte according to Embodiment 4. Figure 11 In the diffraction pattern shown, the intensity of the peak indicates a specific peak of intensity 1. In intensity measurement methods, such as... Figure 11 As shown, the average intensity 1 in the range of +0.45° to +0.55° is calculated from the diffraction angle 2θ of the peak of a specific peak, and the average intensity 2 in the range of -0.55° to -0.45° is further calculated from the diffraction angle 2θ of the peak of the specific peak. Then, the arithmetic mean of the average intensity 1 and the average intensity 2 is calculated, and the ratio of intensity 1 to the arithmetic mean is obtained as the intensity ratio.

[0388] Under the condition Y above, it means that there is no crystal structure or almost no crystal structure in the lithium-based solid electrolyte, and it is in an amorphous state.

[0389] That is, peaks 1 to 4 described in requirement Y are mainly derived from the crystal structure of the lithium-based solid electrolyte (especially the crystal structure of lithium tetraborate). In the absence of these peaks, since the lithium-based solid electrolyte does not have a defined crystal structure and is in an amorphous state, it is presumed, as described above, that a hydrated layer with excellent ion conductivity is easily formed. Furthermore, even if at least one of peaks 1 to 4 is present, if the intensity ratio of any one of the specific peaks present is below a specified value, it indicates that a crystal structure is almost non-existent in the lithium-based solid electrolyte, and as described above, it is presumed that a hydrated layer with excellent ion conductivity is easily formed. In addition, in lithium-based solid electrolytes, peaks caused by other factors may sometimes occur besides peaks derived from a defined crystal structure, such as the crystal structure of lithium tetraborate, as an example. Examples of other factors include peaks derived from specific components (e.g., lithium salts), which sometimes overlap with peaks 1 to 4 described above. In the case of achieving an amorphous state that can be presumed to be capable of forming a hydrated layer with excellent ion conductivity, in most cases the first to fourth peaks are reduced. Assuming as described above, even if a peak based on other factors accidentally overlaps with any one of the first to fourth peaks and a large peak appears, the existence of a specific peak with an intensity ratio below a specified value can also be considered an amorphous state that shows that the lithium-based solid electrolyte can form a hydrated layer with excellent ion conductivity.

[0390] The above X-ray diffraction measurements were performed using CuK α rays and under measurement conditions of 0.01° / spacing and 3° / min.

[0391] In the X-ray diffraction pattern obtained by using CuK α rays in the fourth embodiment of the lithium-based solid electrolyte, it is more preferable that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, and the intensity ratio of at least one of the specific peaks is 3.0 or less. More preferably, in the case that peaks 1, 2, 3, and 4 are all absent, or that a specific peak selected from peaks 1, 2, 3, and 4 is present, the intensity ratio of at least one of the specific peaks is 2.0 or less.

[0392] Furthermore, in the X-ray diffraction pattern of requirement Y, if there are two or more peaks with a full width at half maximum (FWHM) of less than 0.65° within the range of 21.6 to 22.0°, the peak with the largest X-ray diffraction intensity is selected as the first peak for determining requirement Y.

[0393] Furthermore, in the X-ray diffraction pattern of requirement Y, if there are two or more peaks with a peak value in the range of 25.4 to 25.8° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest diffraction X-ray intensity is selected as the second peak for determining requirement Y.

[0394] Furthermore, in the X-ray diffraction pattern of requirement Y, if there are two or more peaks with a peak value in the range of 33.4 to 33.8° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the third peak for determining requirement Y.

[0395] Furthermore, in the X-ray diffraction pattern of requirement Y, if there are two or more peaks with a peak value in the range of 34.4 to 34.8° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest diffraction X-ray intensity is selected as the fourth peak for determining requirement Y.

[0396] The fourth embodiment of the lithium-based solid electrolyte of the present invention satisfies the following requirement Z.

[0397] Requirement Z: In the infrared absorption spectrum of the fourth embodiment of the lithium-based solid electrolyte, 3000–3500 cm⁻¹ -1 The maximum absorption intensity in the wavenumber region is relative to 800–1600 cm⁻¹ -1 The ratio of the maximum absorption intensity in the wavenumber region is more than 1 / 5.

[0398] The aforementioned element Z has the same characteristics as those described in the first embodiment, and its preferred range and measurement method are also as described above.

[0399] In the fourth embodiment of the lithium-based solid electrolyte of the present invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of Li, the molar amount of Li is preferably 1.58 to 3.49. That is, when the molar content of B is set to 4.00, the relative value of the molar content of Li is preferably 1.58 to 3.49.

[0400] From the viewpoint of achieving better results in this invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of Li, the molar amount of Li is more preferably 1.58 to 3.00, further preferably 1.90 to 3.00, and especially preferably 2.00 to 3.00.

[0401] In the fourth embodiment of the lithium-based solid electrolyte of the present invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of O, the molar amount of O is preferably 6.23 to 25.00. That is, when the molar content of B is set to 4.00, the relative value of the molar content of O is preferably 6.23 to 25.00.

[0402] From the viewpoint of achieving better results with the present invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of O, the molar amount of O is more preferably 10.00 to 23.00.

[0403] The fourth embodiment of the lithium-based solid electrolyte of the present invention preferably further includes one or more specific elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H and N, and more preferably includes two or more.

[0404] In the fourth embodiment of the lithium-based solid electrolyte of the present invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of a specific element, the molar amount of each specific element is preferably 0.001 to 10.00. That is, when the molar content of B is set to 4.00, the relative value of the molar content of each specific element is preferably 0.001 to 10.00.

[0405] From the viewpoint of achieving better results with the present invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of a specific element, the molar amounts of each specific element are more preferably 0.001 to 6.0, and even more preferably 0.01 to 5.0.

[0406] As described above, in the fourth embodiment of the lithium-based solid electrolyte of the present invention, it is preferable to include two or more specific elements. Therefore, for example, when the fourth embodiment of the lithium-based solid electrolyte of the present invention includes two specific elements, namely, specific element A and specific element B (a different type of specific element A), and the molar amount of B in the lithium-based solid electrolyte is set to 4.00, the molar amounts of specific element A and specific element B are preferably 0.001 to 10.00, respectively. Furthermore, for example, when the fourth embodiment of the lithium-based solid electrolyte of the present invention includes three specific elements, namely, specific element A, specific element B (a different type of specific element A), and specific element C (a different type of specific element A and B), and the molar amount of B in the lithium-based solid electrolyte is set to 4.00, the molar amounts of specific element A, specific element B, and specific element C are preferably 0.001 to 10.00, respectively.

[0407] In the fourth embodiment of the lithium-based solid electrolyte of the present invention, the contents of Li, B, and specific elements are determined by known elemental analysis. For example, Li and B are analyzed using ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry); one specific element, such as N, is analyzed using an inert gas fusion method; and one specific element, such as F and S, is analyzed using combustion ion chromatography. Regarding O, the analytical masses of all elements except O can be added together and the result calculated as the difference from the total powder volume. Furthermore, the method for calculating the content of each element is not limited to the above; the content of other elements can be estimated based on the analytical results of the content of one element, taking into account the structure of the compound used.

[0408] The molar amounts of Li, O, and specific elements are calculated by determining the content of each element based on elemental analysis, with the molar amount of B set to 4.00.

[0409] As one of the preferred embodiments of the lithium-based solid electrolyte of the present invention, a lithium-based solid electrolyte comprising Li, B, O, F, S and N is provided, wherein when the molar amount of B is 4.00, the molar amount of Li is 1.58 to 3.49 (preferably 1.58 to 3.00), the molar amount of O is 6.23 to 25.00, the molar amount of F is 0.001 to 10.00, the molar amount of S is 0.001 to 2.00, and the molar amount of N is 0.001 to 1.00.

[0410] The preferred range of the above molar ratio is as described above.

[0411] Furthermore, the fourth embodiment of the lithium-based solid electrolyte of the present invention may contain Li, B, O and other elements other than specific elements.

[0412] The manufacturing method of the fourth embodiment of the lithium-based solid electrolyte of the present invention will be described in detail later. The lithium-based solid electrolyte of the present invention is preferably manufactured by a manufacturing method accompanied by mechanical grinding. For example, it is speculated that by mechanically grinding the raw materials (e.g., lithium oxides containing Li and B) of the fourth embodiment of the lithium-based solid electrolyte of the present invention, the crystalline components in the raw materials can be amorphized, and as a result, a hydrated layer with excellent ion conductivity becomes easier to form.

[0413] Furthermore, from the viewpoint of achieving even better results from the present invention, the fourth embodiment of the lithium-based solid electrolyte of the present invention was tested at 120°C. 7 The full width at half maximum (FWHM) of the peaks with chemical shifts in the range of -100 to +100 ppm obtained during Li-NMR measurements is comparable to that of the solid lithium-based solid electrolyte of the fourth embodiment of the present invention, which was subjected to testing at 20°C. 7 In Li-NMR measurements, the proportion of the full width at half maximum (FWHM) of peaks with chemical shifts in the range of -100 to +100 ppm is preferably 50% or less, more preferably 40% or less, and even more preferably 35% or less. There is no particular limitation on the lower limit, but it is usually 10% or more.

[0414] The full width at half peak (FWHM) refers to the width (ppm) at half the height (H) of the peak (H / 2).

[0415] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0416] Furthermore, from the viewpoint of achieving superior effects, the fourth embodiment of the lithium-based solid electrolyte of the present invention was tested at 20°C. 7 When performing waveform separation on the first peak appearing in the range of -100 to +100 ppm in the spectrum obtained during Li-NMR determination, it is preferable to have a second peak with a full width at half maximum (FWHM) of 5 ppm or less in the range of -3 to 3 ppm chemical shift, and the ratio of the area intensity of the second peak to the area intensity of the first peak is 0.5% or more. More preferably, this ratio is 2% or more, and even more preferably 15% or more. There is no particular upper limit to the ratio of the area intensity, but in most cases it is 50% or less.

[0417] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0418] Furthermore, from the viewpoint of achieving superior results, it is preferable to use Raman spectroscopy based on the 600–850 cm⁻¹ range in the fourth embodiment of the lithium-based solid electrolyte of the present invention. -1 The coefficient of determination obtained by least squares linear regression analysis within the wavenumber region is above 0.9400.

[0419] Furthermore, from the viewpoint of achieving better results with the present invention, the aforementioned coefficient of determination is more preferably 0.9600 or higher. There is no particular upper limit, but 1.0000 can be cited as an example.

[0420] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0421] Furthermore, from the viewpoint of achieving better results, the fourth embodiment of the lithium-based solid electrolyte of the present invention preferably satisfies requirement T.

[0422] The following requirement T is the same as the requirement T specified in the first embodiment described above, and its measurement method is also as described in the first embodiment.

[0423] Requirement T: In the Raman spectrum of lithium-based solid electrolytes, at 710–730 cm⁻¹ -1 It has a peak and a half-peak width of 5cm. -1 The first peak mentioned above is between 770 and 790 cm. -1 It has a peak and a half-peak width of 5cm. -1 The second peak mentioned above is located at 1020–1040 cm⁻¹. -1 It has a peak and a half-peak width of 5cm. -1 The third peak mentioned above does not exist, or,

[0424] In the Raman spectrum described above, if at least one specific peak selected from the first peak, the second peak, and the third peak is present, the ratio of the intensity of the peak to the intensity of at least one specific peak calculated by the following intensity measurement method is 5.0 or less.

[0425] Intensity measurement method: The above Raman spectra are measured at 400–600 cm⁻¹. -1 The minimum Raman intensity M1 in the wavenumber region represents the Raman spectrum in the range of 1300–1500 cm⁻¹. -1 A straight line is obtained by connecting the points representing the minimum Raman intensity M2 in the wavenumber region. In the region from the wavenumber representing the minimum M1 to the wavenumber representing the minimum M2, the values ​​excluding 710–730 cm⁻¹ are calculated. -1 770~790cm -1 and 1020~1040cm -1The average difference between the Raman intensity of the aforementioned straight line and the Raman intensity of the Raman spectrum at each wavenumber in regions outside the aforementioned region is calculated. The absolute value of the difference between the Raman intensity of the aforementioned peak and the Raman intensity of the aforementioned straight line at the wavenumber representing the peak of the aforementioned specific peak is calculated. The ratio of the absolute value of the aforementioned difference to the absolute value of the aforementioned average difference is taken as the intensity ratio.

[0426] In the Raman spectrum of the aforementioned lithium-based solid electrolyte, if peaks 1, 2, and 3 are absent, or if a specific peak selected from peaks 1, 2, and 3 is present, the intensity ratio of at least one of the specific peaks is more preferably 3.0 or less. Wherein, if peaks 1, 2, and 3 are absent, or if a specific peak selected from peaks 1, 2, and 3 is present, the intensity ratio of at least one of the specific peaks is further preferably 2.0 or less, and particularly preferably, peaks 1, 2, and 3 are absent.

[0427] Furthermore, from the viewpoint of further enhancing the effects of the present invention, the mass reduction rate when the lithium-based solid electrolyte of the fourth embodiment of the present invention is heated to 800°C is preferably 20 to 40% by mass. From the viewpoint of further enhancing the effects of the present invention, a mass reduction rate of 25 to 35% by mass is more preferable.

[0428] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0429] The bulk modulus of the lithium-based solid electrolyte of the present invention is not particularly limited in the fourth embodiment, but from the viewpoint of better performance of the present invention, it is preferably 45 GPa or less, more preferably 40 GPa or less. The lower limit is not particularly limited, but 5 GPa or more is preferred.

[0430] The above-mentioned characteristics are as described in the first embodiment, and the measurement method is also as described in the first embodiment.

[0431] The median particle size (D50) of the lithium-based solid electrolyte of the present invention in the fourth embodiment is not particularly limited, but from the viewpoint of better performance of the present invention, it is preferably 0.01 to 20 μm, more preferably 0.1 to 2.0 μm.

[0432] The method for determining the median particle size (D50) described above involves obtaining a particle image using flow cytometry particle image analysis, calculating the particle size distribution of the fourth embodiment of the lithium-based solid electrolyte of the present invention, and analyzing the obtained distribution. Furthermore, the aforementioned particle size is equivalent to the diameter of an equivalent circle.

[0433] <<Fifth Implementation Method>>

[0434] The fifth embodiment of the lithium-based solid electrolyte of the present invention includes amorphous LiB3O5 and Li3B 11O 18 Or Li3B7O 12 Water and lithium salts.

[0435] The following is a detailed description of each component.

[0436] (Amorphous LiB3O5, Li3B) 11 O 18 Or Li3B7O 12 (Hereinafter also referred to as "specific boric acid compounds".)

[0437] The fifth embodiment of the lithium-based solid electrolyte of the present invention includes amorphous LiB3O5 and Li3B 11 O 18 Or Li3B7O 12 .

[0438] The compound represented by LiB3O5 is mainly composed of Li, B, and O, but in this invention, it can deviate from the above standard values. More specifically, Li is preferred. 1+x B 3+y O 5+z The compounds represented by (-0.3 < x < 0.3, -0.3 < y < 0.3, -0.3 < z < 0.3).

[0439] Li3B 11 O 18 The compounds represented are primarily composed of Li, B, and O; however, in this invention, deviations from the above standard values ​​are permissible. More specifically, Li is preferred. 3+x B 11+y O 18+z The compounds represented by (-0.3 < x < 0.3, -0.3 < y < 0.3, -0.3 < z < 0.3).

[0440] Li3B7O 12 The compounds represented are primarily composed of Li, B, and O; however, in this invention, deviations from the above standard values ​​are permissible. More specifically, Li is preferred. 3+x B 7+y O 12+z The compounds represented by (-0.3 < x < 0.3, -0.3 < y < 0.3, -0.3 < z < 0.3).

[0441] Amorphous LiB3O5 refers to LiB3O5 that satisfies the following requirement Y2.

[0442] Requirement Y2: In the X-ray diffraction pattern obtained by using CuK α rays in the X-ray diffraction measurement of LiB3O5, the following peaks are absent: the first peak with a peak value of less than 0.65° in the range of 15.4–15.8°; the second peak with a peak value of less than 0.65° in the range of 23.4–23.8°; the third peak with a peak value of less than 0.65° in the range of 26.8–27.2°; and the fourth peak with a peak value of less than 0.65° in the range of 29.4–29.8°. Alternatively, if at least one specific peak selected from the first, second, third, and fourth peaks is present in the X-ray diffraction pattern, the intensity ratio of at least one of the specific peaks calculated by the following intensity measurement method is less than 5.0.

[0443] Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak, and calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak. Calculate the arithmetic mean of the above average intensity 1 and the above average intensity 2, and set the ratio of the peak intensity of the peak of the specific peak to the above arithmetic mean as the intensity ratio.

[0444] Specifically, in element Y2, in the X-ray diffraction pattern obtained from X-ray diffraction of LiB3O5 using CuK α rays, it is preferable that peaks 1, 2, 3, and 4 are all absent, or if a specific peak selected from peaks 1, 2, 3, and 4 is present, the intensity ratio of at least one of the specific peaks is 3.0 or less. More preferably, if peaks 1, 2, 3, and 4 are all absent, or if a specific peak selected from peaks 1, 2, 3, and 4 is present, the intensity ratio of at least one of the specific peaks is 2.0 or less.

[0445] Li3B in its amorphous state 11 O 18 This refers to Li3B that satisfies the following condition Y3. 11 O 18 .

[0446] Requirement Y3: In Li3B 11 O 18In X-ray diffraction patterns obtained using CuK α-rays, the following conditions must be met: 1st peak with a peak value between 19.7 and 20.1° and a full width at half maximum (FWHM) of less than 0.65°; 2nd peak with a peak value between 22.3 and 22.7° and a FWHM of less than 0.65°; and 3rd peak with a peak value between 27.3 and 27.7° and a FWHM of less than 0.65°. Alternatively, if at least one specific peak selected from the 1st, 2nd, and 3rd peaks exists in the X-ray diffraction pattern, the intensity ratio of at least one of these specific peaks, calculated by the following intensity measurement method, is less than 5.0.

[0447] Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak, and calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak. Calculate the arithmetic mean of the above average intensity 1 and the above average intensity 2, and set the ratio of the peak intensity of the peak of the specific peak to the above arithmetic mean as the intensity ratio.

[0448] Among them, in element Y3, in Li3B 11 O 18 In the X-ray diffraction pattern obtained by using CuK α rays, it is preferable that peaks 1, 2, and 3 are all absent, or that a specific peak selected from peaks 1, 2, and 3 is present, and at least one of the specific peaks has an intensity ratio of 3.0 or less. More preferably, if peaks 1, 2, and 3 are all absent, or if a specific peak selected from peaks 1, 2, and 3 is present, at least one of the specific peaks has an intensity of 2.0 or less.

[0449] Amorphous Li3B7O 12 This refers to Li3B7O that satisfies the following condition Y4. 12 .

[0450] Requirement Y4: In Li3B7O 12 In the X-ray diffraction pattern obtained by using CuK α rays, the first peak, which has a peak in the range of 16.5 to 16.9° and a full width at half maximum (FWHM) of less than 0.65°, does not exist. In the case where the first peak exists in the X-ray diffraction pattern, at least one of the first peaks has an intensity ratio of less than 5.0 calculated by the following intensity measurement method.

[0451] Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak, and calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak. Calculate the arithmetic mean of the above average intensity 1 and the above average intensity 2, and set the ratio of the peak intensity of the peak of the specific peak to the above arithmetic mean as the intensity ratio.

[0452] Among them, in element Y4, in Li3B7O 12 In the X-ray diffraction pattern obtained by using CuK α rays, it is preferable that the first peak is absent, or if the first peak is present, the intensity ratio of the first peak is 3.0 or less. More preferably, if the first peak is absent, or if the first peak is present, the intensity ratio of the first peak is 2.0 or less.

[0453] The above-mentioned requirements Y2 to Y4 can be calculated using the same steps, except that the object to be measured in requirement Y is changed and the position of the detected peak is changed respectively.

[0454] Similar to requirement Y, elements Y2 to Y4 are peaks originating from the crystal structure of a specific boric acid compound. If these peaks are absent, it is assumed that the specific boric acid compound does not possess the prescribed crystal structure but rather an amorphous structure, thus, as described above, it is likely that a hydrated layer with excellent ion conductivity will easily form. Furthermore, similar to requirement Y, even if specific peaks are present, if the intensity ratio of any one of these specific peaks is below a predetermined value, it indicates that a crystal structure is almost nonexistent in the specific boric acid compound, and as described above, it is likely that a hydrated layer with excellent ion conductivity will easily form.

[0455] In addition, in the X-ray diffraction pattern of requirement Y2, if there are two peaks with a peak value in the range of 15.4 to 15.8° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the first peak for determining requirement Y2.

[0456] Furthermore, in the X-ray diffraction pattern of requirement Y2, there are more than two peaks with a peak value in the range of 23.4 to 23.8° and a full width at half maximum (FWHM) of less than 0.65°. The peak with the largest X-ray diffraction intensity is selected as the second peak for determining requirement Y2.

[0457] Furthermore, in the X-ray diffraction pattern of requirement Y2, if there are two or more peaks with a peak value in the range of 26.8 to 27.2° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the third peak for determining requirement Y2.

[0458] Furthermore, in the X-ray diffraction pattern of requirement Y2, if there are two or more peaks with a peak value in the range of 29.4 to 29.8° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the fourth peak for determining requirement Y2.

[0459] In addition, in the X-ray diffraction pattern of requirement Y3, if there are two or more peaks with a peak value in the range of 19.7 to 20.1° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the first peak for determining requirement Y3.

[0460] Furthermore, in the X-ray diffraction pattern of requirement Y3, if there are two or more peaks with a peak value in the range of 22.3 to 22.7° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the second peak for determining requirement Y3.

[0461] Furthermore, in the X-ray diffraction pattern of requirement Y3, if there are two or more peaks with a peak value in the range of 27.3 to 27.7° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the third peak for determining requirement Y3.

[0462] In addition, if there are two or more peaks in the X-ray diffraction pattern of requirement Y4 with a peak value in the range of 16.5 to 16.9° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the first peak for determining requirement Y4.

[0463] From the viewpoint of achieving better results in this invention, the amorphous LiB3O5 preferably satisfies the following requirement X2.

[0464] Regarding the following requirement X2, except that amorphous LiB3O5 is used as the test object, it is an requirement evaluated by the same steps as requirement W described above, and the evaluation method is as described above.

[0465] Requirement X2: In the reduced-dibule distribution function G(r) obtained from X-ray total scattering measurements of amorphous LiB3O5, there exists a peak located at r. The first peak and the apex within the range are located at r. The G(r) of the second peak, the peak of the first peak, and the peak of the second peak within the range indicate that the value is greater than 1.0.

[0466] From the viewpoint of achieving superior results in this invention, the amorphous state of Li3B... 11 O 18 Preferably, the following requirement X3 is met.

[0467] Regarding the following requirement X3, besides the amorphous state of Li3B 11 O 18 Aside from the object to be measured, it is an element that is evaluated using the same steps as element W described above, and the evaluation method is as described above.

[0468] Requirement X3: In the amorphous state of Li3B 11 O 18 In the reduced two-body distribution function G(r) obtained from X-ray total scattering measurements, there exists a peak located at r. The first peak and the apex within the range are located at r. The G(r) of the second peak, the peak of the first peak, and the peak of the second peak within the range indicate that the value is greater than 1.0.

[0469] From the viewpoint that the present invention offers superior performance, crystalline Li3B7O... 12 Preferably, the following requirement X4 is met.

[0470] Regarding the following requirement X4, besides the amorphous state of Li3B7O 12 Aside from the object to be measured, it is an element that is evaluated using the same steps as element W described above, and the evaluation method is as described above.

[0471] Requirement X4: From the amorphous state of Li3B7O 12 In the reduced two-body distribution function G(r) obtained from X-ray total scattering measurements, there exists a peak located at r. The first peak and the apex within the range are located at r. The G(r) of the second peak, the peak of the first peak, and the peak of the second peak within the range indicate that the value is greater than 1.0.

[0472] Furthermore, in elements X2 to X4, as with element X, their technical meaning is as described above, that is, the periodic structure corresponding to the interatomic distance of B (boron)-O (oxygen) and the interatomic distance of B (boron)-B (boron) exists in a specific boric acid compound.

[0473] There are no particular limitations on the methods for manufacturing specific boric acid compounds; examples include the preparation of crystalline compounds such as LiB3O5 and Li3B. 11 O 18 Or Li3B7O 12 The manufacturing method involves performing the mechanical grinding process described later.

[0474] (water)

[0475] The fifth embodiment of the lithium-based solid electrolyte of the present invention includes water.

[0476] The water content in the fifth embodiment of the lithium-based solid electrolyte of the present invention is not particularly limited. However, from the viewpoint of better performance of the present invention, the molar ratio of water to a specific boric acid compound (molar amount of water / molar amount of a specific boric acid compound) in the third embodiment of the lithium-based solid electrolyte of the present invention is preferably 3 to 15, more preferably 4 to 13, further preferably 5 to 13, and particularly preferably 10 to 13.

[0477] (Lithium salt)

[0478] The fifth embodiment of the lithium-based solid electrolyte of the present invention includes a lithium salt.

[0479] There are no particular restrictions on the types of lithium salts. Examples of lithium salts shown in step 1A described later will be given in detail in the following section.

[0480] The lithium salt content in the fifth embodiment of the lithium-based solid electrolyte of the present invention is not particularly limited.

[0481] In the fifth embodiment of the lithium-based solid electrolyte of the present invention, the mass ratio of the lithium salt content to the specific lithium tetraborate content (mass of lithium salt content / mass of specific boric acid compound content) is not particularly limited. However, from the viewpoint of better effects of the present invention, the molar ratio of lithium salt to specific boric acid compound (molar amount of lithium salt / molar amount of specific boric acid compound) in the fifth embodiment of the lithium-based solid electrolyte of the present invention is preferably 0.001 to 1.2, more preferably 0.01 to 1.2, further preferably 0.1 to 1.2, and particularly preferably 0.5 to 1.2.

[0482] In the case where the fifth embodiment of the lithium-based solid electrolyte of the present invention includes amorphous LiB3O5, the fifth embodiment of the lithium-based solid electrolyte of the present invention preferably satisfies the following requirement Y5. Requirement Y5 is a requirement that, except that the lithium-based solid electrolyte is used as the object of measurement, it is evaluated using the same steps as requirement Y2.

[0483] Requirement Y5: In the X-ray diffraction pattern obtained by using CuK α rays in the X-ray diffraction measurement of the lithium-based solid electrolyte, the following peaks are absent: the first peak with a peak value of less than 0.65° in the range of 15.4–15.8°; the second peak with a peak value of less than 0.65° in the range of 23.4–23.8°; the third peak with a peak value of less than 0.65° in the range of 26.8–27.2°; and the fourth peak with a peak value of less than 0.65° in the range of 29.4–29.8°. Alternatively, in the X-ray diffraction pattern, if at least one specific peak selected from the first, second, third, and fourth peaks is present, the intensity ratio of at least one of the specific peaks calculated by the following intensity measurement method is less than 5.0.

[0484] Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak, and calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak. Calculate the arithmetic mean of the above average intensity 1 and the above average intensity 2, and set the ratio of the peak intensity of the peak of the specific peak to the above arithmetic mean as the intensity ratio.

[0485] Specifically, in element Y5, in the X-ray diffraction pattern obtained by X-ray diffraction measurement using CuK α rays in the lithium-based solid electrolyte, it is preferable that peaks 1, 2, 3, and 4 are all absent, or if a specific peak selected from peaks 1, 2, 3, and 4 is present, the intensity ratio of at least one of the specific peaks is 3.0 or less. More preferably, if peaks 1, 2, 3, and 4 are all absent, or if a specific peak selected from peaks 1, 2, 3, and 4 is present, the intensity ratio of at least one of the specific peaks is 2.0 or less.

[0486] Furthermore, the fifth embodiment of the lithium-based solid electrolyte of the present invention includes amorphous Li3B. 11 O 18 In this case, the fifth embodiment of the lithium-based solid electrolyte of the present invention preferably satisfies the following requirement Y6. Requirement Y6 is a requirement that, apart from using the lithium-based solid electrolyte as the object of measurement, it is evaluated through the same steps as requirement Y3.

[0487] Requirement Y6: In the X-ray diffraction pattern obtained by using CuK α rays in the X-ray diffraction measurement of the lithium-based solid electrolyte, the following conditions must be met: the first peak with a peak value in the range of 19.7–20.1° and a full width at half maximum (FWHM) of less than 0.65°, the second peak with a peak value in the range of 22.3–22.7° and a FWHM of less than 0.65°, and the third peak with a peak value in the range of 27.3–27.7° and a FWHM of less than 0.65° are all absent; or, in the X-ray diffraction pattern, if at least one specific peak selected from the first, second, and third peaks is present, the intensity ratio of at least one of the specific peaks calculated by the following intensity measurement method is 5.0 or less.

[0488] Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak, and calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak. Calculate the arithmetic mean of the above average intensity 1 and the above average intensity 2, and set the ratio of the peak intensity of the peak of the specific peak to the above arithmetic mean as the intensity ratio.

[0489] Specifically, in element Y6, in the X-ray diffraction pattern obtained by using CuK α rays in the X-ray diffraction measurement of the lithium-based solid electrolyte, preferably, peaks 1, 2, and 3 are all absent, or if a specific peak selected from peaks 1, 2, and 3 is present, the intensity ratio of at least one of the specific peaks is 3.0 or less. More preferably, if peaks 1, 2, and 3 are all absent, or if a specific peak selected from peaks 1, 2, and 3 is present, the intensity of at least one of the specific peaks is 2.0 or less.

[0490] Furthermore, in the case where the fifth embodiment of the lithium-based solid electrolyte of the present invention includes amorphous Li3B7O12, the fifth embodiment of the lithium-based solid electrolyte of the present invention preferably satisfies the following requirement Y7. Requirement Y7 is a requirement that, apart from using the lithium-based solid electrolyte as the object of measurement, it is evaluated using the same steps as requirement Y4.

[0491] Requirement Y7: ​​In the X-ray diffraction pattern obtained by using CuK α rays in the X-ray diffraction measurement of the lithium-based solid electrolyte, the first peak with a apex in the range of 16.5 to 16.9° and a full width at half maximum (FWHM) of 0.65° or less is not present, or in the case of the presence of the first peak in the X-ray diffraction pattern, the intensity ratio of at least one of the first peaks calculated by the following intensity measurement method is 5.0 or less.

[0492] Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak, and calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak. Calculate the arithmetic mean of the above average intensity 1 and the above average intensity 2, and set the ratio of the peak intensity of the peak of the specific peak to the above arithmetic mean as the intensity ratio.

[0493] Specifically, in element Y7, in the X-ray diffraction pattern obtained by using CuK α rays in X-ray diffraction measurement of the lithium-based solid electrolyte, preferably, if the first peak is absent or present, the intensity ratio of the first peak is 3.0 or less. More preferably, if the first peak is absent or present, the intensity ratio of the first peak is 2.0 or less.

[0494] Furthermore, in the X-ray diffraction pattern of requirement Y5, if there are two or more peaks with a peak value in the range of 15.4 to 15.8° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the first peak for determining requirement Y5.

[0495] Furthermore, in the X-ray diffraction pattern of requirement Y5, if there are two or more peaks with a peak value in the range of 23.4 to 23.8° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest diffraction X-ray intensity is selected as the second peak for determining requirement Y5.

[0496] Furthermore, in the X-ray diffraction pattern of requirement Y5, if there are two or more peaks with a peak value in the range of 26.8 to 27.2° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the third peak for determining requirement Y5.

[0497] Furthermore, in the X-ray diffraction pattern of requirement Y5, if there are two or more peaks with a peak value in the range of 29.4 to 29.8° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the fourth peak for determining requirement Y5.

[0498] In addition, in the X-ray diffraction pattern of requirement Y6, if there are two or more peaks with a peak value in the range of 19.7 to 20.1° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the first peak for determining requirement Y6.

[0499] Furthermore, in the X-ray diffraction pattern of requirement Y6, if there are two or more peaks with a peak value in the range of 22.3 to 22.7° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the second peak for determining requirement Y6.

[0500] Furthermore, in the X-ray diffraction pattern of requirement Y6, if there are two or more peaks with a peak value in the range of 27.3 to 27.7° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest diffraction X-ray intensity is selected as the third peak for determining requirement Y6.

[0501] In addition, in the X-ray diffraction pattern of requirement Y7, if there are two or more peaks with a peak value in the range of 16.5 to 16.9° and a full width at half maximum (FWHM) of less than 0.65°, the peak with the largest X-ray diffraction intensity is selected as the first peak for determining requirement Y7.

[0502] From the viewpoint of achieving better results, the fifth embodiment of the lithium-based solid electrolyte of the present invention preferably satisfies the following requirement X5.

[0503] Regarding the following requirement X5, except that the fifth embodiment of the lithium-based solid electrolyte of the present invention is used as the test object, it is an requirement evaluated by the same steps as requirement W described above, and the evaluation method is as described above.

[0504] Requirement X5: In the reduced-dimer distribution function G(r) obtained from the X-ray total scattering measurement of the fifth embodiment of the lithium-based solid electrolyte, there exists a peak located at r. The first peak and the apex within the range are located at r. The G(r) of the second peak, the peak of the first peak, and the peak of the second peak within the range indicate that the value is greater than 1.0.

[0505] Inorganic Solid Electrolytes

[0506] <First Implementation>

[0507] The first embodiment of the inorganic solid electrolyte of the present invention is an inorganic solid electrolyte having conductive ions selected from metal elements belonging to Group 1 of the periodic table and elements belonging to Group 2 of the periodic table.

[0508] Metallic elements, which belong to Group 1 of the periodic table, are elements other than H (hydrogen) that are listed as Group 1 elements in the periodic table. Examples include Li, Na, K, Rb, Cs, and Fr.

[0509] Furthermore, as Group 2 elements of the periodic table, examples include Be, Mg, Ca, Sr, Ba, and Ra.

[0510] Preferably, the inorganic solid electrolyte has the conductivity of Li ions.

[0511] The first embodiment of the inorganic solid electrolyte of the present invention comprises a metal element selected from Group 1 elements of the periodic table and an element from Group 2 elements of the periodic table (hereinafter also simply referred to as "element X"), B, and O.

[0512] As for element X, the above examples can be cited, with Li being the preferred choice.

[0513] Furthermore, the first embodiment of the inorganic solid electrolyte of the present invention further includes two or more specific elements selected from Group 3, Group 4, Group 13, Group 14, Group 15, Group 16, Group 17 of the periodic table, and H. The first embodiment of the inorganic solid electrolyte of the present invention may include three or more specific elements. From the viewpoint of achieving better results, it is preferable that the inorganic solid electrolyte includes two to five specific elements, more preferably two to four.

[0514] As elements in Group 3 of the periodic table, examples include Sc, Y, the lanthanides, and the actinides.

[0515] Examples of elements in Group 4 of the periodic table include Ti, Zr, Hf, and Rf.

[0516] Elements belonging to Group 13 of the periodic table include B, Al, Ga, In, Tl, and Nh.

[0517] Elements belonging to Group 14 of the periodic table include C, Si, Ge, Sn, Pb, and Fl.

[0518] Elements belonging to group 15 of the periodic table include N, P, As, Sb, Bi, and Mc.

[0519] Elements belonging to Group 16 of the periodic table include 0, S, Se, Te, Po, and Lv.

[0520] Elements belonging to group 17 of the periodic table include F, Cl, Br, I, At, and Ts.

[0521] The first embodiment of the inorganic solid electrolyte of the present invention preferably contains two or more specific elements selected from F, S, N, P and C, more preferably contains two or more specific elements selected from F, S, C and N, and even more preferably contains three specific elements: F, S and N.

[0522] In the first embodiment of the inorganic solid electrolyte of the present invention, when the molar amount of B in the inorganic solid electrolyte is set to 4.00 to represent the molar amount of element X, the molar amount of element X is preferably 0.001 to 1000. That is, when the molar content of B is set to 4.00, the relative value of the molar content of element X is preferably 0.001 to 1000.

[0523] From the viewpoint of achieving better results in this invention, when the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amount of element X, the molar amount of element X is more preferably 0.1 to 10, further preferably 1.58 to 3.49, especially preferably 1.58 to 3.00, even more preferably 1.90 to 3.00, and most preferably 2.00 to 3.00.

[0524] In the first embodiment of the inorganic solid electrolyte of the present invention, when the molar amount of B in the inorganic solid electrolyte is set to 4.00 to represent the molar amount of O, the molar amount of O is preferably 0.001 to 1000. That is, when the molar content of B is set to 4.00, the relative value of the molar content of element O is preferably 0.001 to 1000.

[0525] From the viewpoint of achieving better results in this invention, when the molar amount of B in the inorganic solid electrolyte is set to 4.00 to represent the molar amount of O, the molar amount of O is more preferably 0.1 to 100, further preferably 6.23 to 25.0, and especially preferably 10.00 to 23.00.

[0526] In the first embodiment of the inorganic solid electrolyte of the present invention, when the molar amount of B in the inorganic solid electrolyte is set to 4.00 to represent the molar amount of a specific element, the molar amount of each specific element is preferably 0.001 to 1000. That is, when the molar content of B is set to 4.00, the relative value of the molar content of each specific element is preferably 0.001 to 1000.

[0527] From the viewpoint of achieving better results in this invention, when the molar amount of B in the inorganic solid electrolyte is set to 4.00 to represent the molar amount of a specific element, the molar amounts of each specific element are more preferably 0.001 to 100, further preferably 0.001 to 6.0, and especially preferably 0.01 to 5.0.

[0528] As described above, in the first embodiment of the inorganic solid electrolyte of the present invention, two or more specific elements are included. Therefore, for example, when the first embodiment of the inorganic solid electrolyte of the present invention includes two specific elements—specific element A and specific element B, which is a different type of specific element A—and the molar amount of B in the inorganic solid electrolyte is set to 4.00, the molar amounts of specific element A and specific element B are preferably 0.001 to 1000, respectively. Furthermore, for example, when the first embodiment of the inorganic solid electrolyte of the present invention includes three specific elements—specific element A, specific element B, which is a different type of specific element A, and specific element C, which is a different type of specific element A and B—and the molar amount of B in the inorganic solid electrolyte is set to 4.00, the molar amounts of specific element A, specific element B, and specific element C are preferably 0.001 to 1000, respectively.

[0529] The contents of elements X, B, and specific elements in the first embodiment of the inorganic solid electrolyte of the present invention were determined by known elemental analysis.

[0530] In addition, the first embodiment of the inorganic solid electrolyte of the present invention may contain elements X, B, O and other elements other than specific elements.

[0531] The first embodiment of the inorganic solid electrolyte of the present invention is amorphous.

[0532] It is speculated that the first embodiment of the inorganic solid electrolyte of the present invention is amorphous and satisfies the requirement R described later, thereby making it easy to generate a soft hydration layer on the surface side of the inorganic solid electrolyte, and the ion conductivity becomes good due to the presence of the hydration layer.

[0533] The first embodiment of the inorganic solid electrolyte of the present invention satisfies the following requirement R.

[0534] Furthermore, regarding requirement R, except that the first embodiment of the inorganic solid electrolyte is used as the object of measurement for requirement Z in the fourth embodiment of the lithium-based solid electrolyte of the present invention described above, the requirement is evaluated using the same steps, and the evaluation method is as described above. When requirement R is met, similar to requirement Z described above, it indicates that the inorganic solid electrolyte contains a plurality of OH groups or a large amount of water.

[0535] Requirement R: In the infrared absorption spectrum of inorganic solid electrolytes, 3000–3500 cm⁻¹ -1 The maximum absorption intensity in the wavenumber region is relative to 800–1600 cm⁻¹ -1 The ratio of the maximum absorption intensity in the wavenumber region is more than 1 / 5.

[0536] <Second Implementation Method>

[0537] A second embodiment of the inorganic solid electrolyte of the present invention comprises: a compound comprising a metal element selected from Group 1 of the periodic table and an element selected from Group 2 of the periodic table (equivalent to element X above), B and O; water; and a salt comprising a metal element selected from Group 1 of the periodic table and an element selected from Group 2 of the periodic table.

[0538] (Compounds containing elements X, B, and O (hereinafter also referred to as "compounds containing element X").)

[0539] A second embodiment of the inorganic solid electrolyte of the present invention comprises a compound containing elements X, B, and O.

[0540] As an example of element X, as described in the first embodiment of the inorganic solid electrolyte above, Li is preferred.

[0541] When element X is Li, examples of the aforementioned compounds include, for instance, Li₂B₄O₇, LiB₃O₅, LiBO₅, and Li₃B₄O₇. 11 O 18 and Li2B7O 12 .

[0542] The above-mentioned compounds are preferably amorphous.

[0543] (water)

[0544] The second embodiment of the inorganic solid electrolyte of the present invention includes water.

[0545] The water content in the second embodiment of the inorganic solid electrolyte of the present invention is not particularly limited. However, from the viewpoint of better performance of the present invention, the molar ratio of water to the compound containing element X (molar amount of water / molar amount of the compound containing element X) in the second embodiment of the inorganic solid electrolyte of the present invention is preferably 3 to 15, more preferably 4 to 13, further preferably 5 to 13, and particularly preferably 10 to 13.

[0546] (Including salts of metals selected from Group 1 and Group 2 elements of the periodic table)

[0547] The second embodiment of the inorganic solid electrolyte of the present invention comprises a salt (hereinafter also simply referred to as "a salt containing element X"), which contains a metal element selected from Group 1 elements of the periodic table and an element from Group 2 elements of the periodic table (equivalent to element X as described above).

[0548] There are no particular restrictions on whether a salt contains element X, as long as it does not contain element X. For example, if element X is Li, the salt containing element X is equivalent to a lithium salt, and if element X is Na, the salt containing element X is equivalent to a sodium salt.

[0549] In salts containing element X, the composition is usually a cation and anion of element X. The structure of the anion is not particularly limited; known anions can be cited, but organic anions are preferred. Among organic ions, organic anions containing fluorine atoms are preferred.

[0550] Salts containing element X preferably contain two or more specific elements selected from Group 3, Group 4, Group 13, Group 14, Group 15, Group 16, Group 17 of the periodic table, and H.

[0551] In the second embodiment of the inorganic solid electrolyte of the present invention, the mass ratio of the salt containing element X to the compound containing element X (mass of salt containing element X / mass of compound containing element X) is not particularly limited. However, from the viewpoint of better effects of the present invention, the molar ratio of the salt containing element X to the compound containing element X (molar amount of salt containing element X / molar amount of compound containing element X) in the second embodiment of the inorganic solid electrolyte of the present invention is preferably 0.001 to 1.5, more preferably 0.001 to 1.2, further preferably 0.01 to 1.2, particularly preferably 0.1 to 1.2, and most preferably 0.5 to 1.2.

[0552] <Manufacturing Methods of Lithium-Based Solid Electrolytes>

[0553] The manufacturing method of the lithium-based solid electrolyte of the present invention (Embodiments 1 to 4) is not particularly limited. From the viewpoint of being able to manufacture the lithium-based solid electrolyte of the present invention with good productivity, the manufacturing method having the following steps 1A to 3A is preferred.

[0554] Step 1A: A step of mechanically grinding lithium oxides containing Li and B in the presence of a specific element source.

[0555] Process 2A: The process of mixing the product obtained in Process 1A with water.

[0556] Step 3A: The process of removing water from the dispersion obtained in Step 2A to obtain a lithium-based solid electrolyte.

[0557] The steps of the above manufacturing method will be described in detail below.

[0558] Step 1A is a process of mechanically grinding lithium oxide containing Li and B in the presence of a specific element source.

[0559] The following is a detailed description of the materials used in process 1A, followed by a detailed description of the process itself.

[0560] The specific element source preferably contains two or more elements selected from Group 4, Group 15, Group 16, Group 17 of the periodic table, Si, C, Sc, Y, and H, and two or more elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H, and N. The specific element source only needs to contain two or more of the above-mentioned elements and can be composed of one compound or two or more compounds. For example, a specific element source may be composed of a compound containing two or more elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H and N, or it may be composed of compound 1 containing at least one element selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H and N and compound 2 containing an element selected from the aforementioned group that is different in type from the elements selected from the aforementioned group contained in compound 1.

[0561] The specific element source preferably contains 2 to 4 elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H and N, and more preferably contains 3 elements.

[0562] As a compound contained in a particular element source, a salt is preferred, and a lithium salt (especially a lithium imide salt) is more preferred.

[0563] As a lithium salt, the compound represented by formula (1) is preferred.

[0564] Equation (1) LiN(R) f1 SO2)(R f2 SO2)

[0565] R f1 and R f2 Each can be represented independently as a halogen atom or a perfluoroalkyl group.

[0566] R f1 and R f2 In the case of perfluoroalkyl groups, there is no particular limitation on the number of carbon atoms in the perfluoroalkyl group.

[0567] R f1 and R f2Preferably, it is a halogen atom or a perfluoroalkyl group having 1 to 6 carbon atoms, more preferably a halogen atom or a perfluoroalkyl group having 1 to 2 carbon atoms, and even more preferably a halogen atom. If the volume of the terminal group increases, the steric hindrance increases, becoming a factor hindering ion conduction; therefore, R... f1 and R f2 In the case of perfluoroalkyl groups, fewer carbon atoms are preferred.

[0568] The following examples illustrate compounds contained in a specific element source. Furthermore, among the compounds illustrated below, as described above, compounds containing only one specific element are used together with other compounds containing at least one other specific element to make the specific element source contain two or more specific elements.

[0569] (L-1) Inorganic lithium salts: Inorganic fluoride salts such as LiPF6, LiBF4, LiAsF6 and LiSbF6; high hydrogen halide salts such as LiClO4, LiBrO4 and LiIO4; inorganic chloride salts such as LiAlCl4.

[0570] (L-2) Fluorinated organic lithium salts: perfluoroalkyl sulfonates such as LiCF3SO3; perfluoroalkyl sulfonyl imide salts such as LiN(CF3SO2)2, LiN(CF3CF2SO2)2, LiN(FSO2)2 and LiN(CF3SO2)(C4F9SO2); perfluoroalkyl sulfonyl methyl salts such as LiC(CF3SO2)3; fluoroalkyl fluorinated phosphates such as Li[PF5(CF2CF2CF3)], Li[PF4(CF2CF2CF3)2], Li[PF3(CF2CF2CF3)3], Li[PF5(CF2CF2CF2CF3)], Li[PF4(CF2CF2CF2CF3)2] and Li[PF3(CF2CF2CF2CF3)3].

[0571] (L-3) Oxalate borate: Lithium bis(oxalate)borate and lithium difluorooxalate borate.

[0572] In addition to the above, examples include LiF, LiCl, LiBr, LiI, Li2SO4, LiNO3, Li2CO3, CH3COOLi, LiAsF6, LiSbF6, LiAlCl4, and LiB(C6H5)4.

[0573] Among them, LiPF6, LiBF4, LiAsF6, LiSbF6, LiClO4, and Li(R) are preferred. f1 SO3), LiN(R) f1 SO2)2, LiN(FSO2)2 or LiN(R f1 SO2)(R f2 SO2), more preferably LiPF6, LiBF4, and LiN(R)f1 SO2)2, LiN(FSO2)2 or LiN(R f1 SO2)(R f2 SO2).

[0574] Here, R f1 and R f2 Each can be represented independently as a perfluoroalkyl group.

[0575] There is no particular limitation on the amount of a specific element source used; the amount used is appropriately adjusted in order to obtain the lithium-based solid electrolyte of the present invention described above.

[0576] The amount of the specific element source used is preferably 1 to 300 parts by mass relative to 100 parts by mass of the lithium oxide containing Li and B, more preferably 100 to 200 parts by mass.

[0577] Examples of lithium oxides containing both Li and B include Li₂B₄O₇, LiBO₅, LiB₃O₅, and Li₃B₄O₇. 11 O 18 Li2B7O 12 LiB2O3(OH)H2O and Li4B8O 12 (OH)2(H2O)3, etc.

[0578] Mechanical grinding is a process that imparts mechanical energy to the sample while simultaneously crushing it.

[0579] As a mechanical grinding process, examples include ball mills, vibratory mills, turbine mills, and disc mills. From the viewpoint of being able to manufacture the lithium-based solid electrolyte of the present invention with good productivity, ball mills are preferred. As ball mills, examples include vibratory ball mills, rotary ball mills, and planetary ball mills, with planetary ball mills being more preferred.

[0580] The appropriate conditions for ball milling can be selected based on the raw materials used.

[0581] There are no particular limitations on the material of the grinding balls (media) used in the ball milling process. For example, agate, silicon nitride, stabilized zirconium oxide (YSZ), alumina and iron alloys can be mentioned. From the viewpoint of being able to manufacture the lithium-based solid electrolyte of the present invention with good productivity, stabilized zirconium oxide (YSZ) is preferred.

[0582] The average particle size of the pulverizing balls is not particularly limited, but from the viewpoint of being able to manufacture the lithium-based solid electrolyte of the present invention with good productivity, 1 to 10 mm is preferred, and 3 to 7 mm is more preferred. The above-mentioned average particle size is obtained by measuring the diameter of any 50 pulverizing balls and taking the arithmetic mean of these. If the pulverizing balls are not spherical, the major axis is taken as the diameter.

[0583] There is no particular limitation on the number of grinding balls used during ball milling. From the viewpoint of being able to manufacture the lithium-based solid electrolyte of the present invention with good productivity, 10 to 100 balls are preferred, and 40 to 60 balls are more preferred.

[0584] There are no particular limitations on the material of the grinding jar used in ball milling. For example, agate, silicon nitride, stabilized zirconium oxide (YSZ), alumina and iron alloys can be mentioned. From the viewpoint of being able to manufacture the lithium-based solid electrolyte of the present invention with good productivity, stabilized zirconium oxide (YSZ) is preferred.

[0585] There is no particular limitation on the rotation speed during ball milling, but from the viewpoint of being able to manufacture the lithium-based solid electrolyte of the present invention with good productivity, 200 to 700 rpm is preferred, and 350 to 550 rpm is more preferred.

[0586] There is no particular limitation on the processing time of the ball mill. From the viewpoint of being able to manufacture the lithium-based solid electrolyte of the present invention with good productivity, a time of 10 to 200 hours is preferred, and a time of 20 to 140 hours is more preferred.

[0587] The atmosphere for ball milling can be atmospheric or in an inert gas atmosphere (e.g., argon, helium, and nitrogen).

[0588] Step 2A is a process of mixing the product obtained in Step 1A with water. By carrying out this step, the lithium oxides of Li and B that have undergone mechanical grinding treatment in Step 1A are mixed with water to generate the lithium solid electrolyte of the present invention containing a large amount of O (oxygen element).

[0589] There is no particular limitation on the amount of water used. From the viewpoint of achieving better results in this invention, the amount of water used is preferably 10 to 200 parts by mass relative to 100 parts by mass of the product obtained in step 1A, and more preferably 50 to 150 parts by mass.

[0590] There are no particular restrictions on the method of mixing the product obtained in step 1A with water; they can be mixed together, or water can be added to the product obtained in step 1A in stages for mixing.

[0591] During mixing, ultrasonic treatment can be performed as needed.

[0592] There is no particular limitation on the duration of ultrasonic treatment, but from the viewpoint of achieving better results in this invention, 10 minutes to 5 hours is preferred.

[0593] Step 3A is a process of removing water from the dispersion obtained in step 2A to obtain a lithium-based solid electrolyte.

[0594] There are no particular restrictions on the method for removing water from the dispersion obtained in step 2A. Water can be removed by heating or by vacuum drying.

[0595] In addition, prior to step 1A above, in the absence of a specific element source, step 0 can be performed to mechanically grind lithium oxides containing Li and B.

[0596] The preferred method for the mechanical grinding process performed in step 0 is the same as the preferred method for the mechanical grinding process performed in step 1A above.

[0597] As another preferred embodiment of the manufacturing method of the lithium-based solid electrolyte of the present invention, a manufacturing method having the following steps 1B to 3B is preferred.

[0598] Step 1B: A step involving mechanical polishing of lithium oxides containing Li and B.

[0599] Process 2B: A process for mixing the product obtained in Process 1B, water, and a specific element source.

[0600] Step 3B: The process of removing water from the dispersion obtained in Step 2B to obtain a lithium-based solid electrolyte.

[0601] Regarding the difference between process 1B and process 1A, one example is that mechanical grinding is performed in process 1A in the presence of a specific element source, while mechanical grinding is performed in process 1B without the use of a specific element source.

[0602] The preferred method for the mechanical grinding process performed in step 1B is the same as the preferred method for the mechanical grinding process performed in step 1A.

[0603] Regarding the difference between step 2B and step 2A, one example is that step 2B involves mixing the products obtained in step 1B, water, and a specific element source.

[0604] The specific element source used in step 2B is the same as the specific element source used in step 1A.

[0605] The amount of a specific element source used in step 2B is preferably 1 to 300 parts by mass relative to 100 parts by mass of the product obtained in step 1B, and more preferably 100 to 200 parts by mass.

[0606] There are no particular restrictions on the steps in step 2B. It can be a method of mixing the product obtained in step 1B, water, and a specific element source together (method 1); or a method of mixing the product obtained in step 1B with water to prepare a solution, and then mixing the prepared solution with the specific element source (method 2); or a method of mixing the product obtained in step 1B with water to prepare solution 1, mixing the specific element source with water to prepare solution 2, and then mixing solution 1 and solution 2 (method 3). When mixing the product obtained in step 1B with water, dispersion treatments such as ultrasonic treatment can be appropriately performed.

[0607] From the viewpoint of achieving better results with the present invention, method 3 is preferred.

[0608] In Method 2, when the solution and the specific element source are mixed by mixing the product obtained in step 1B with water, if the amount of the specific element source is too large, the resulting solution is prone to gelation, making it difficult to increase the amount of the specific element source mixed. In contrast, in Method 3, even when the product obtained in step 1B and the specific element source are mixed in approximately equimolar amounts, gelation of the solution is less likely to occur, and it is easier to increase the amount of the specific element source mixed.

[0609] The process of process 3B is the same as that of process 3A.

[0610] As another preferred embodiment of the manufacturing method of the lithium-based solid electrolyte of the present invention, a manufacturing method having the following steps 1C to 3C is preferred.

[0611] Step 1C: A step of mechanically grinding lithium oxides containing Li and B.

[0612] Step 2C: A step involving mixing the product obtained in Step 1C with water.

[0613] Step 3C: This step involves mixing the product obtained by removing water from the dispersion obtained in Step 2C with a specific element source to obtain a lithium-based solid electrolyte.

[0614] The process of process 1C is the same as that of process 1B.

[0615] The process of process 2C is the same as that of process 2A.

[0616] The difference between step 3C and step 3A can be cited as an example of mixing the product obtained by removing water from the dispersion obtained in step 2C with a specific element source.

[0617] The specific element source used in process 3C is the same as the specific element source used in process 1A.

[0618] The amount of the specific element source used in step 3C is preferably 1 to 300 parts by mass relative to 100 parts by mass of the product obtained by removing water from the dispersion obtained in step 2C, more preferably 100 to 200 parts by mass.

[0619] There are no particular limitations on the method of mixing the product obtained by removing water from the dispersion obtained in step 2C with the source of a specific element. Alternatively, the product can be mixed by impregnating a solution obtained by dissolving the source of the specific element in water with the product.

[0620] That is, the preferred embodiment of the method for manufacturing the lithium-based solid electrolyte of the present invention includes:

[0621] Step 1: Mechanical grinding is performed on lithium oxides containing Li and B;

[0622] Step 2 involves mixing the product obtained in Step 1 with water; and

[0623] Step 3 involves removing water from the dispersion obtained in Step 2 to obtain a lithium-based solid electrolyte.

[0624] Manufacturing methods that satisfy any of the following requirements 1 to 3 can be cited.

[0625] Requirement 1: Mechanical grinding process of step 1 is carried out in the presence of a specific element source.

[0626] Requirement 2: In step 2, the product, water, and a specific element source are mixed.

[0627] Requirement 3: In step 3, the product obtained by removing water from the dispersion obtained in step 2 and a specific element source are mixed to obtain a lithium-based solid electrolyte.

[0628] Furthermore, while the above description describes the use of a specific element source containing two or more elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H, and N, the method for manufacturing the lithium-based solid electrolyte of the present invention is not limited to this method.

[0629] For example, in the fourth embodiment of the lithium-based solid electrolyte of the present invention described above, it may contain one or more elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H, and N. To contain such one or more elements, a specific element source may be used, comprising one or more elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H, and N.

[0630] <Methods for Manufacturing Inorganic Solid Electrolytes>

[0631] The method for manufacturing the inorganic solid electrolyte of the present invention (first embodiment to second embodiment) is not particularly limited, and known methods can be used.

[0632] Preferably, the lithium-based solid electrolyte of the present invention is manufactured using the same steps as described above, except that an oxide containing elements X and B is used instead of a lithium oxide containing Li and B, and a salt containing element X is used instead of a specific element source.

[0633] <Dispersion>

[0634] The dispersion of the present invention comprises the lithium-based solid electrolyte or inorganic solid electrolyte of the present invention described above and a solvent (e.g., an organic solvent, water). The dispersion of the present invention is in liquid form and can be coated onto various substrates, and is useful for the manufacture of solid electrolyte layers.

[0635] The content of lithium-based solid electrolyte or inorganic solid electrolyte in the dispersion of the present invention is not particularly limited, but is preferably 5 to 80% by mass, more preferably 30 to 70% by mass, relative to the total mass of the dispersion.

[0636] The solvent content in the dispersion of the present invention is not particularly limited, but is preferably 20-95% by mass, more preferably 30-70% by mass, relative to the total mass of the dispersion.

[0637] The dispersion of the present invention may contain other components besides the lithium-based solid electrolyte or inorganic solid electrolyte and solvent of the present invention.

[0638] Adhesives can be cited as an example of other components.

[0639] Various organic polymers can be cited as adhesives.

[0640] The organic polymers that make up adhesives can be in particulate or non-particulate form.

[0641] Furthermore, other solid electrolytes besides the lithium-based solid electrolyte or inorganic solid electrolyte of the present invention can be cited as other components. Other solid electrolytes refer to solid electrolytes capable of ion movement within them. Inorganic solid electrolytes are preferred as solid electrolytes.

[0642] Other examples of solid electrolytes include sulfide-based inorganic solid electrolytes, oxide-based inorganic solid electrolytes, halogen-based inorganic solid electrolytes, and hydride-based solid electrolytes.

[0643] The method for manufacturing the dispersion of the present invention is not particularly limited. For example, a manufacturing method having the above-described steps 1A and 2A, and a manufacturing method having steps 1B and 2B can be cited.

[0644] <Applications>

[0645] The lithium-based solid electrolyte and inorganic solid electrolyte of the present invention exhibit excellent ionic conductivity, thus making them suitable for a wide range of applications. For example, the lithium-based solid electrolyte and inorganic solid electrolyte of the present invention can be used in various batteries (e.g., all-solid-state secondary batteries, solid oxide fuel cells, and batteries using solid oxide vapor electrolysis). The lithium-based solid electrolyte of the present invention is preferably used in all-solid-state lithium-ion secondary batteries.

[0646] More specifically, the lithium-based solid electrolyte and inorganic solid electrolyte of the present invention are preferably used in the formation of solid electrolytes contained in the positive electrode active material layer, solid electrolyte layer, and negative electrode active material layer in an all-solid-state secondary battery. Specifically, the lithium-based solid electrolyte of the present invention is preferably used to form the solid electrolyte contained in the positive electrode active material layer, solid electrolyte layer, and negative electrode active material layer in an all-solid-state lithium-ion secondary battery. Furthermore, the lithium-based solid electrolyte of the present invention is preferably used as the solid electrolyte contained in any one of the positive electrode active material layer, solid electrolyte layer, and negative electrode active material layer in an all-solid-state lithium-ion secondary battery.

[0647] Furthermore, the lithium-based solid electrolyte and inorganic solid electrolyte of the present invention can preferably be used as coating materials for coating the surface of the positive electrode active material. That is, as one of the preferred embodiments of the present invention, a modified positive electrode active material can be provided, which has a positive electrode active material and a coating layer disposed on the positive electrode active material, the coating layer comprising the lithium-based solid electrolyte or inorganic solid electrolyte of the present invention.

[0648] Furthermore, the lithium-based solid electrolyte and inorganic solid electrolyte of the present invention are preferably used as coating materials for coating the surface of the negative electrode active material. That is, as one of the preferred embodiments of the present invention, a modified negative electrode active material is provided, which has a negative electrode active material and a coating layer disposed on the negative electrode active material, the coating layer comprising the lithium-based solid electrolyte or inorganic solid electrolyte of the present invention.

[0649] When using the lithium-based solid electrolyte and inorganic solid electrolyte of the present invention, it is preferable to subject the lithium-based solid electrolyte and inorganic solid electrolyte of the present invention to pressure treatment and mold them into a predetermined shape for use.

[0650] There are no particular restrictions on the method of pressurization; for example, a method using a known pressurization device can be cited.

[0651] There are no particular limitations on the pressure applied during the pressurization process, and the optimal pressure can be selected appropriately. However, from the viewpoint of achieving better results from the present invention, 5 to 1500 MPa is preferred, and 10 to 600 MPa is more preferred.

[0652] There is no particular limitation on the time of pressurization, but from the viewpoint of better performance of the present invention and productivity, 1 second to 0.5 hours is preferred, and 2 seconds to 0.2 hours is more preferred.

[0653] Furthermore, during the pressurization process, heat treatment can be performed. There are no particular limitations on the heating temperature during heat treatment, but 40–400°C is preferred, and 50–350°C is more preferred. The heating time during heat treatment is preferably 1 minute to 6 hours.

[0654] There are no particular restrictions on the atmosphere used in the pressurization process; examples include atmospheric conditions, dry air (dew point below -20°C), and inert gas atmospheres (e.g., argon, helium, and nitrogen).

[0655] The ionic conductivity (27°C) of the lithium-based solid electrolyte and inorganic solid electrolyte of the present invention is not particularly limited, but from the viewpoint of application to various purposes, 1.0 × 10⁻⁶ is preferred. -5 S / cm or higher, more preferably 1.0×10 -4 Above S / cm. There is no specific upper limit, but it is usually 1.0 × 10⁻⁶. -2 Below S / cm.

[0656] The dispersion of the present invention, which contains the lithium-based solid electrolyte or inorganic solid electrolyte of the present invention, can preferably be used as a dispersion for forming a solid electrolyte layer.

[0657] There are no particular limitations on the method of forming a solid electrolyte layer using the above-mentioned dispersion for forming a solid electrolyte layer; for example, a method of forming a solid electrolyte layer by coating with the dispersion for forming a solid electrolyte layer can be cited. Furthermore, the formed coating film can be subjected to pressure treatment as needed.

[0658] There are no particular limitations on the coating method of the dispersion used to form the solid electrolyte layer. Examples include spraying, spin coating, dip coating, slot coating, aerosol deposition, thermal spraying, and rod coating.

[0659] Furthermore, after applying the dispersion for forming the solid electrolyte layer, the obtained coating film can be dried as needed. There are no particular limitations on the drying temperature, but a lower limit is preferably 30°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. An upper limit is preferably 300°C or lower, more preferably 250°C or lower.

[0660] There are no particular limitations on the method of pressurizing the coating; for example, the method can be described using a known pressurizing device (e.g., a hydraulic cylinder press).

[0661] There are no particular limitations on the pressure applied during the pressurization process. However, from the viewpoint that the solid electrolyte layer formed has better ion conductivity, 5 to 1500 MPa is preferred, and 300 to 600 MPa is more preferred.

[0662] There is no particular limitation on the time of pressurization treatment, but from the viewpoint of better ion conductivity of the formed solid electrolyte layer and productivity, 1 minute to 6 hours is preferred, and 1 to 20 minutes is more preferred.

[0663] Furthermore, during the pressurization process, heat treatment can be performed. There are no particular limitations on the heating temperature during heat treatment, but 30 to 300°C is preferred, and the heating time is more preferably 1 minute to 6 hours.

[0664] There are no particular restrictions on the atmosphere used in the pressurization process; examples include atmospheric conditions, dry air (dew point below -20°C), and inert gas atmospheres (e.g., argon, helium, and nitrogen).

[0665] The lithium-based solid electrolyte and inorganic solid electrolyte of the present invention are also preferably used as components of the electrode forming composition. That is, the electrode forming composition of the present invention includes the lithium-based solid electrolyte of the present invention described above.

[0666] The electrode forming composition of the present invention comprises the lithium-based solid electrolyte or inorganic solid electrolyte of the present invention described above and an active material.

[0667] There are no particular limitations on the mixing ratio of lithium-based solid electrolyte or inorganic solid electrolyte to active material in the electrode forming composition, and there are no particular limitations on the content ratio of lithium-based solid electrolyte or inorganic solid electrolyte to active material (mass of lithium-based solid electrolyte or inorganic solid electrolyte / mass of active material), preferably 0.01 to 50, more preferably 0.05 to 20.

[0668] The lithium-based solid electrolyte and inorganic solid electrolyte contained in the electrode forming composition are as described above.

[0669] Examples of active materials include negative electrode active materials and positive electrode active materials. The following is a detailed description of active materials.

[0670] (Negative electrode active material)

[0671] The negative electrode active material is preferably capable of reversibly inserting or releasing lithium ions. There are no particular limitations on the negative electrode active material; examples include carbonaceous materials, oxides of metals or metalloids, lithium monomers, lithium alloys, and negative electrode active materials capable of forming alloys with lithium.

[0672] Carbonaceous materials used as negative electrode active materials refer to materials that are essentially composed of carbon. Examples include carbonaceous materials made by calcining petroleum asphalt, carbon black such as acetylene black (AB), graphite (natural graphite and artificial graphite such as vapor-grown graphite), and various synthetic resins such as PAN (polyacrylonitrile) resin or furfuryl alcohol resin.

[0673] In addition, examples include various types of carbon fibers such as PAN-based carbon fibers, cellulose-based carbon fibers, pitch-based carbon fibers, vapor-grown carbon fibers, dehydrated PVA (polyvinyl alcohol)-based carbon fibers, lignin carbon fibers, glassy carbon fibers, and activated carbon fibers, as well as mesophase microspheres, graphite whiskers, and flat graphite.

[0674] These carbonaceous materials can also be classified according to the degree of graphitization into non-graphitizable carbonaceous materials (also known as hard carbon) and graphitic carbonaceous materials.

[0675] Furthermore, the carbonaceous material preferably has the facet spacing, density, or crystallite size described in Japanese Patent Application Publication No. 62-022066, Japanese Patent Application Publication No. 2-006856, and Japanese Patent Application Publication No. 3-045473. The carbonaceous material need not be a single material; mixtures of natural and artificial graphite as described in Japanese Patent Application Publication No. 5-090844 and coated graphite as described in Japanese Patent Application Publication No. 6-004516 can also be used.

[0676] As a carbonaceous material, hard carbon or graphite is preferred, with graphite being more preferred.

[0677] There are no particular restrictions on the use of oxides of metal elements or half-metal elements as negative electrode active materials, as long as they can adsorb and release lithium. Examples include oxides of metal elements (metal oxides), composite oxides of metal elements, composite oxides of metal elements and half-metal elements, and oxides of half-metal elements (half-metal oxides). In addition, composite oxides of metal elements and composite oxides of metal elements and half-metal elements are also collectively referred to as metal composite oxides.

[0678] As these oxides, amorphous oxides are preferred, and chalcogenides, which are reaction products of metal elements with elements of group 16 of the periodic table, are also preferred.

[0679] In this invention, metalloid elements refer to elements that exhibit intermediate properties between metallic and nonmetallic elements. They typically include six elements: boron, silicon, germanium, arsenic, antimony, and tellurium, as well as three elements: selenium, polonium, and astatine.

[0680] Furthermore, the amorphous material refers to the X-ray diffraction of CuK α rays, which exhibits a broad scattering band with a vertex in the 2θ value range of 20–40°, and may also possess crystalline diffraction lines. Among the crystalline diffraction lines observed in the 2θ value range of 40–70°, the strongest intensity is preferably less than 100 times that of the diffraction line at the vertex of the broad scattering band observed in the 2θ value range of 20–40°, more preferably less than 5 times, and even more preferably a non-crystalline diffraction line.

[0681] Among the group of compounds consisting of the above-mentioned amorphous oxides and chalcogenides, amorphous oxides of half-metallic elements or the above-mentioned chalcogenides are more preferred, and oxides or chalcogenides consisting of one or more of the elements selected from groups 13(IIIB) to 15(VB) of the periodic table (e.g., Al, Ga, Si, Sn, Ge, Pb, Sb and Bi) alone or in combination of two or more of these are even more preferred.

[0682] As amorphous oxides and chalcogenides, Ga2O3, GeO, PbO, PbO2, Pb2O3, Pb2O4, Pb3O4, Sb2O3, Sb2O4, Sb2O8Bi2O3, Sb2O8Si2O3, Sb2O5, Bi2O3, Bi2O4, GeS, PbS, PbS2, Sb2S3, or Sb2S5 are preferred.

[0683] As a negative electrode active material that can be used together with amorphous oxide negative electrode active materials centered on Sn, Si or Ge, carbonaceous materials, lithium monomers, lithium alloys, or negative electrode active materials that can adsorb and / or release lithium ions or lithium metal are preferred.

[0684] From the viewpoint of high current density charge and discharge characteristics, oxides of metal elements or half-metal elements (especially metal (composite) oxides) and the aforementioned chalcogenides preferably include at least one of titanium and lithium as constituent components.

[0685] Examples of lithium-containing metal composite oxides (lithium composite metal oxides) include, for example, composite oxides of lithium oxide with the aforementioned metal oxides, the aforementioned metal composite oxides, or the aforementioned chalcogenides. More specifically, Li₂SnO₂ can be cited as an example.

[0686] The negative electrode active material (e.g., metal oxide) preferably also contains titanium (titanium oxide). Specifically, since Li4Ti5O 12 Lithium titanate (LTO) exhibits small volume changes during lithium ion adsorption and release, resulting in excellent rapid charge and discharge characteristics. From the viewpoint of improving the lifespan of all-solid-state lithium-ion secondary batteries that can suppress electrode degradation, it is preferred.

[0687] There are no particular restrictions on lithium alloys that can be used as negative electrode active materials, as long as they are alloys commonly used as negative electrode active materials in all-solid-state lithium-ion secondary batteries. For example, lithium-aluminum alloys can be cited.

[0688] There are no particular restrictions on the negative electrode active material that can form an alloy with lithium, as long as it is a material commonly used as a negative electrode active material in all-solid-state lithium-ion secondary batteries. Examples of such negative electrode active materials include negative electrode active materials (alloys) containing silicon or tin, as well as various metals such as Al and In. It is preferable to use a negative electrode active material containing silicon, which can achieve higher battery capacity. More preferably, it is an active material containing silicon with a silicon content of 50 mol% or more of all constituent elements.

[0689] Generally speaking, negative electrodes containing these active materials (e.g., Si negative electrodes containing silicon-containing active materials, Sn negative electrodes containing tin-containing active materials) can retain more Li ions compared to carbon negative electrodes (graphite and acetylene black, etc.). That is, the amount of Li ions retained per unit mass increases. This increases battery capacity. Consequently, it has the advantage of extending battery operating time.

[0690] Examples of silicon-containing active materials include silicon materials such as Si and SiOx (0 < x ≤ 1), as well as silicon-containing alloys (e.g., LaSi2, VSi2, La-Si, Gd-Si, and Ni-Si) or structured active materials (e.g., LaSi2 / Si) containing titanium, vanadium, chromium, manganese, nickel, copper, or lanthanum. Furthermore, examples of active materials containing both silicon and tin include SnSiO3 and SnSiS3. Regarding SiOx, it can be used as a negative electrode active material (metal oxide-like material), and since Si is generated through the driving force of an all-solid-state lithium-ion secondary battery, it can be used as a negative electrode active material (its precursor material) capable of alloying with lithium.

[0691] Examples of anode active materials containing tin include active materials containing Sn, SnO, SnO2, SnS, SnS2, and the aforementioned silicon and tin elements.

[0692] From the viewpoint of battery capacity, as a negative electrode active material, a negative electrode active material that can form an alloy with lithium is preferred, silicon material or silicon-containing alloy (alloy containing silicon element) is more preferred, and silicon (Si) or silicon-containing alloy is even more preferred.

[0693] The shape of the negative electrode active material is not particularly limited, but particulate form is preferred. The volume average particle size of the negative electrode active material is not particularly limited, but 0.1 to 60 μm is preferred, 0.5 to 20 μm is more preferred, and 1.0 to 15 μm is even more preferred.

[0694] The volume average particle size was determined by the following steps.

[0695] A dispersion of 1% by mass of the negative electrode active material was prepared by diluting it in water (heptane if it is unstable in water) in a 20 mL sample vial. The diluted dispersion sample was immediately used in the experiment after being irradiated with ultrasound at 1 kHz for 10 minutes. Using this dispersion sample, and employing a laser diffraction / scattering particle size distribution measuring device at 25°C using a measuring quartz cell, data were obtained for 50 measurements to obtain the volume average particle size. For other detailed conditions, refer to JIS Z 8828:2013 "Particle Size Analysis - Dynamic Light Scattering Method" as needed. Five samples were prepared for each level, and their average value was used.

[0696] One type of negative electrode active material can be used alone, or two or more types can be used simultaneously.

[0697] The surface of the negative electrode active material can be coated with other metal oxides.

[0698] As surface covering agents, examples include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li. Specifically, examples include spinel titanate, tantalum oxides, niobium oxides, and lithium niobate compounds, such as Li₄Ti₅O₂. 12 Li2Ti2O5, LiTaO3, LiNbO3, LiAlO2, Li2ZrO3, Li2WO4, Li2TiO3, Li2B4O7, Li3PO4, Li2MoO4, Li3BO3, LiBO2, Li2CO3, Li2SiO3, SiO2, TiO2, ZrO2, Al2O3 and B2O3.

[0699] Furthermore, the electrode surface containing the negative electrode active material can be surface-treated with sulfur or phosphorus.

[0700] Furthermore, the particle surface of the negative electrode active material can be surface-treated by photochemical rays or active gas (e.g., plasma) before and after the aforementioned surface coating.

[0701] (Positive electrode active material)

[0702] The positive electrode active material is preferably capable of reversibly inserting and / or releasing lithium ions. There are no particular limitations on the positive electrode active material, but transition metal oxides are preferred, and materials containing the transition metal element M are more preferred. aA transition metal oxide (selected from one or more elements chosen from Co, Ni, Fe, Mn, Cu, and V). Furthermore, element M can be mixed into this transition metal oxide. b (Elements from Group 1(Ia) and Group 2(IIa) of the periodic table, excluding lithium, and elements such as Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B). As a mixing amount, it is preferable to use elements relative to transition metal M. a The amount (100 mol%) is 0–30 mol%. More preferably, Li / M a The molar ratios were mixed to a ratio of 0.3 to 2.2 for synthesis.

[0703] Specific examples of transition metal oxides include (MA) transition metal oxides with a layered rock-salt structure, (MB) transition metal oxides with a spinel-type structure, (MC) lithium-containing transition metal phosphate compounds, (MD) lithium-containing transition metal halide phosphate compounds, and (ME) lithium-containing transition metal silicate compounds. Among these, (MA) is preferably a transition metal oxide with a layered rock-salt structure, and more preferably LiCoO2 or LiNi. 1 / 3 C o1 / 3 Mn 1 / 3 O2.

[0704] (MA) is a transition metal oxide with a layered rock salt-type structure. Examples of its applications include LiCoO2 (lithium cobalt oxide [LCO]), LiNi2O2 (lithium nickel oxide), and LiNi 0.85 C o0.10 Al 0.05 O2 (lithium nickel cobalt aluminum oxide [NCA]), LiNi 1 / 3 C o1 / 3 Mn 1 / 3 O2 (lithium nickel manganese cobalt oxide [NMC]) and LiNi 0.5 Mn 0.5 O2 (lithium manganese nickel oxide).

[0705] (MB) is a transition metal oxide with a spinel-type structure, for example, LiMn2O4(LMO), LiCoMnO4, Li2FeMn3O8, Li2CuMn3O8, Li2CrMn3O8 and Li2NiMn3O8.

[0706] (MC) is a lithium-containing transition metal phosphate compound. Examples include olivine-type iron phosphates such as LiFePO4 and Li3Fe2(PO4)3, iron pyrophosphates such as LiFeP2O7, cobalt phosphates such as LiCoPO4, and monoclinic NASICON-type vanadium phosphates such as Li3V2(PO4)3 (lithium vanadium phosphate).

[0707] (MD) is a lithium-containing transition metal halide phosphate compound, for example, iron fluorophosphate such as Li2FePO4F, manganese fluorophosphate such as Li2MnPO4F, and cobalt fluorophosphate such as Li2CoPO4F.

[0708] (ME) is a lithium-containing transition metal silicate compound, for example, Li2FeSiO4, Li2MnSiO4 and Li2CoSiO4.

[0709] The shape of the positive electrode active material is not particularly limited, but particulate form is preferred. The volume average particle size of the positive electrode active material is not particularly limited, but 0.1–50 μm is preferred. The volume average particle size of the positive electrode active material can be measured in the same manner as that of the negative electrode active material described above.

[0710] Positive electrode active materials obtained by calcination can be used after being cleaned with water, acidic aqueous solutions, alkaline aqueous solutions, or organic solvents.

[0711] Similar to the negative electrode active material, the positive electrode active material can also be further coated with the above-mentioned surface covering agent, sulfur or phosphorus, by photochemical radiation.

[0712] One type of positive electrode active material can be used alone, or two or more types can be used simultaneously.

[0713] The composition for forming electrodes may also contain other components besides lithium-based solid electrolytes, inorganic solid electrolytes and active materials.

[0714] The composition for forming electrodes may contain conductive additives.

[0715] As conductive additives, substances generally known as conductive additives can be used. Examples of conductive additives include graphite materials such as natural and artificial graphite, carbon blacks such as acetylene black, Ketjen black, and furnace black, amorphous carbon such as needle coke, fibrous carbon such as vapor-grown carbon fibers and carbon nanotubes, and carbonaceous materials such as graphene and fullerenes. Furthermore, conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives can be used.

[0716] In addition to the conductive additives mentioned above, conventional conductive additives that do not contain carbon atoms, such as metal powder or metal fiber, can be used.

[0717] Furthermore, conductive additives refer to substances that do not involve the insertion and release of Li during battery charging and discharging, and do not function as active materials. Therefore, among conductive additives, substances that function as active materials in the active material layer during battery charging and discharging are also classified as active materials rather than conductive additives. Whether a substance functions as an active material during battery charging and discharging cannot be uniquely determined, but rather through its combination with the active material.

[0718] Furthermore, the aforementioned adhesives and lithium salts can also be cited as other components.

[0719] The composition for electrode formation may contain a dispersion medium.

[0720] Examples of dispersion media include, for example, water and various organic solvents.

[0721] The electrode forming composition may include, in addition to the components mentioned above, ionic liquids, thickeners, crosslinking agents (substances that undergo crosslinking reactions through free radical polymerization, condensation polymerization or ring-opening polymerization), polymerization initiators (substances that generate acids or free radicals through heat or light, etc.), defoamers, leveling agents, dehydrating agents and antioxidants.

[0722] There are no particular limitations on the method for forming electrodes (negative electrode active material layer and positive electrode active material layer) using the above-described electrode forming composition; for example, a method for forming electrodes by coating the electrode forming composition can be cited. Furthermore, the formed coating film can be subjected to pressure treatment as needed.

[0723] There are no particular limitations on the coating method of the composition for electrode formation. Examples include spraying, spin coating, dip coating, slot coating, aerosol deposition, thermal spraying, and bar coating.

[0724] Furthermore, after applying the electrode forming composition, the obtained coating film can be dried as needed. There are no particular limitations on the drying temperature, but a lower limit is preferably 30°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. An upper limit is preferably 300°C or lower, more preferably 250°C or lower.

[0725] There are no particular limitations on the method of pressurizing the coating; for example, the method can be described using a known pressurizing device (e.g., a hydraulic cylinder press).

[0726] There are no particular limitations on the pressure applied during the pressurization process, but 5 to 1500 MPa is preferred, and 300 to 600 MPa is more preferred.

[0727] There is no particular limitation on the time of pressurization, but from a productivity point of view, 1 minute to 6 hours is preferred, and 1 to 20 minutes is more preferred.

[0728] Furthermore, during the pressurization process, heat treatment can be carried out. There are no particular limitations on the heating temperature during heat treatment, but 30 to 300°C is preferred, and the heating time is preferably 1 minute to 6 hours.

[0729] There are no particular restrictions on the atmosphere used in the pressurization process; examples include atmospheric conditions, dry air (dew point below -20°C), and inert gas atmospheres (e.g., argon, helium, and nitrogen).

[0730] <Solid Electrolyte Tablets>

[0731] The lithium-based solid electrolyte and inorganic solid electrolyte of the present invention can be contained in a solid electrolyte sheet.

[0732] The above-mentioned solid electrolyte sheet is preferably used as a solid electrolyte sheet for all-solid-state batteries.

[0733] The aforementioned solid electrolyte sheet can be formed by molding the lithium-based solid electrolyte or inorganic solid electrolyte of the present invention into a sheet shape. There are no particular limitations on the molding method; for example, a sheet can be formed by pressing a dispersion containing the lithium-based solid electrolyte or inorganic solid electrolyte of the present invention.

[0734] <Electrode sheets for all-solid-state secondary batteries>

[0735] The lithium-based solid electrolyte and inorganic solid electrolyte of the present invention can be incorporated into the electrode sheet for all-solid-state secondary batteries. In particular, the lithium-based solid electrolyte of the present invention can be incorporated into the electrode sheet for all-solid-state lithium-ion secondary batteries.

[0736] The following section provides a detailed description of the electrode sheets used in all-solid-state lithium-ion secondary batteries.

[0737] The electrode sheet for all-solid-state lithium-ion secondary batteries of the present invention is a sheet-shaped molded body capable of forming an electrode active material layer of an all-solid-state lithium-ion secondary battery, and can preferably be used as an electrode or a laminate of an electrode and a solid electrolyte layer.

[0738] Regarding the all-solid-state lithium-ion secondary battery electrode sheet (also simply referred to as "electrode sheet") of the present invention, any electrode sheet having an active material electrode layer (hereinafter also simply referred to as "active material electrode layer") selected from a negative electrode active material layer and a positive electrode active material layer is acceptable. It can be a sheet in which the active material electrode layer is formed on a substrate (current collector), or a sheet without a substrate but formed from the active material electrode layer. This electrode sheet is typically a sheet having a current collector and an active material electrode layer, but it also includes a configuration in which the current collector, active material electrode layer, and solid electrolyte layer are sequentially formed, as well as a configuration in which the current collector, active material electrode layer, solid electrolyte layer, and active material electrode layer are sequentially formed.

[0739] The electrode sheet of the present invention may have the other layers described above. The layer thickness of each layer constituting the electrode sheet of the present invention is the same as the layer thickness described later in the description of the all-solid-state lithium-ion secondary battery.

[0740] Regarding the all-solid-state lithium-ion secondary battery sheet of the present invention, at least one layer of the active material electrode layer contains the lithium-based solid electrolyte of the present invention.

[0741] The method for manufacturing the electrode sheet for all-solid-state lithium-ion secondary batteries of the present invention is not particularly limited. For example, the electrode forming composition of the present invention can be used, and the electrode sheet can be manufactured by forming an active material electrode layer.

[0742] For example, a method can be described as forming a coating film by coating an electrode forming composition onto a current collector (which may be separated by other layers), and then subjecting the coating film to pressure treatment.

[0743] Methods for coating electrode forming compositions and methods for applying pressure to coating films can be described in the electrode forming compositions.

[0744] All-solid-state rechargeable batteries

[0745] The all-solid-state secondary battery of the present invention comprises a positive electrode active material layer, a negative electrode active material layer opposite to the positive electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. Preferably, the positive electrode active material layer is formed on a positive electrode current collector and constitutes the positive electrode. Preferably, the negative electrode active material layer is formed on a negative electrode current collector and constitutes the negative electrode.

[0746] Preferably, at least one of the negative electrode active material layer, the positive electrode active material layer, and the solid electrolyte layer contains the lithium-based solid electrolyte or inorganic solid electrolyte of the present invention, including the lithium-based solid electrolyte.

[0747] That is, the present invention also relates to active materials and electrodes for all-solid-state secondary batteries having an active material layer and a current collector comprising the lithium-based solid electrolyte or inorganic solid electrolyte of the present invention.

[0748] The following is a detailed description of the all-solid-state lithium-ion secondary battery of the present invention.

[0749] The all-solid-state lithium-ion secondary battery of the present invention comprises a positive electrode active material layer, a negative electrode active material layer opposite to the positive electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. Preferably, the positive electrode active material layer is formed on the positive electrode current collector and constitutes the positive electrode. Preferably, the negative electrode active material layer is formed on the negative electrode current collector and constitutes the negative electrode.

[0750] At least one of the negative electrode active material layer, the positive electrode active material layer, and the solid electrolyte layer contains the lithium-based solid electrolyte of the present invention.

[0751] There are no particular limitations on the thickness of the negative electrode active material layer, the solid electrolyte layer, and the positive electrode active material layer. Considering the size of a typical all-solid-state lithium-ion secondary battery, the thickness of each layer is preferably 10 to 1000 μm, more preferably 20 μm or more and less than 500 μm.

[0752] The thickness of at least one of the positive electrode active material layer and the negative electrode active material layer is further preferably 50 μm or more and less than 500 μm.

[0753] The positive electrode active material layer and the negative electrode active material layer may each have a current collector on the side opposite to the solid electrolyte layer.

[0754] The all-solid-state lithium-ion secondary battery of the present invention can be used as an all-solid-state lithium-ion secondary battery in the above-described structural state, depending on the application, but is preferably used as a dry cell battery, further encapsulated in a suitable frame. The frame can be a metallic frame or a resin (plastic) frame. Examples of metallic frames include aluminum alloy frames and stainless steel frames. The metallic frame is preferably divided into a positive electrode side frame and a negative electrode side frame, which electrically connect the positive electrode current collector and the negative electrode current collector, respectively. The positive electrode side frame and the negative electrode side frame are preferably joined by a short-circuit prevention gasket and are integrated into one unit.

[0755] The following is for reference. Figure 7 The mechanical properties of the all-solid-state lithium-ion secondary battery according to the preferred embodiment of the present invention are described, but the present invention is not limited thereto.

[0756] Figure 7 This is a schematic cross-sectional view illustrating a preferred embodiment of the all-solid-state lithium-ion secondary battery of the present invention. When viewed from the negative electrode side, the all-solid-state lithium-ion secondary battery 10 of this embodiment sequentially comprises a negative electrode current collector 1, a negative electrode active material layer 2, a solid electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode current collector 5.

[0757] At least one of the negative electrode active material layer 2, the positive electrode active material layer 4, and the solid electrolyte layer 3 contains the lithium-based solid electrolyte of the present invention.

[0758] Each layer is in contact with its own adjacent structure. By employing this structure, electrons (electrons) are supplied to the negative electrode side during charging. - ), in which lithium ions (Li + On the other hand, during discharge, lithium ions (Li) accumulated at the negative electrode are stored. +The electrons return to the positive side and supply electrons to the working part 6. In the illustrated example, a light bulb is simulated in the working part 6 and is set to be lit by discharging.

[0759] The negative electrode active material layer 2 contains the aforementioned negative electrode active material.

[0760] The positive electrode active material layer 4 contains the aforementioned positive electrode active material.

[0761] The positive current collector 5 and the negative current collector 1 are preferably electron conductors.

[0762] Materials that form the positive current collector include aluminum, aluminum alloys, stainless steel, nickel, and titanium, with aluminum or aluminum alloys being preferred. Alternatively, materials that have been treated on the surface of aluminum or stainless steel with carbon, nickel, titanium, or silver (substances forming thin films) can also be used as positive current collectors.

[0763] Materials that form the negative current collector include aluminum, copper, copper alloys, stainless steel, nickel, and titanium, with aluminum, copper, copper alloys, or stainless steel being preferred. Additionally, materials that have been treated with carbon, nickel, titanium, or silver on the surface of aluminum, copper, copper alloys, or stainless steel can also be used as negative current collectors.

[0764] The current collector is usually in the shape of a thin film, but it can also be in other shapes.

[0765] There is no particular limitation on the thickness of the current collector, but it is preferably 1 to 500 μm.

[0766] Furthermore, the surface of the current collector is preferably given an uneven surface through surface treatment.

[0767] The manufacturing method of the above-described all-solid-state lithium-ion secondary battery is not particularly limited, and known methods can be cited. Among them, the method of using the above-described electrode forming composition and / or solid electrolyte layer forming dispersion is preferred.

[0768] For example, it is possible to obtain an all-solid-state lithium-ion secondary battery by coating a positive electrode forming composition containing a positive electrode active material onto a positive electrode current collector, i.e., a metal foil, to form a positive electrode active material layer; then, coating a dispersion for forming a solid electrolyte layer onto the positive electrode active material layer to form a solid electrolyte layer; further coating a negative electrode forming composition containing a negative electrode active material onto the solid electrolyte layer to form a negative electrode active material layer; stacking a negative electrode current collector (metal foil) on the negative electrode active material layer; and further subjecting the obtained laminate to pressure treatment to sandwich a solid electrolyte layer between the positive and negative electrode active material layers. It is also possible to encapsulate this in a housing as a desired all-solid-state lithium-ion secondary battery.

[0769] Furthermore, by reversing the formation methods of each layer, a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer can be formed on the negative electrode current collector, and the positive electrode current collector can be overlapped to manufacture an all-solid-state lithium-ion secondary battery.

[0770] Furthermore, as another method, an all-solid-state lithium-ion secondary battery can be manufactured by separately fabricating the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer, and then stacking these layers together.

[0771] All-solid-state lithium-ion secondary batteries are preferably initialized after manufacturing or before use. There are no particular limitations on initialization; for example, it can be performed by initially charging and discharging under increased pressure, and then releasing the pressure until it reaches the normal operating pressure of an all-solid-state lithium-ion secondary battery.

[0772] <Applications of all-solid-state secondary batteries>

[0773] The all-solid-state secondary battery (especially the all-solid-state lithium-ion secondary battery) of the present invention is applicable to a wide variety of uses. There are no particular limitations on its application; for example, when incorporated into electronic devices, it can be used in laptops, pen-and-paper computers, mobile computers, e-book readers, mobile phones, cordless phones, pagers, handheld terminals, portable fax machines, portable copiers, portable printers, stereo headphones, video players, LCD TVs, handheld cleaners, portable CD players, microCD players, electric shavers, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, and backup power supplies. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game consoles, load conditioners, clocks, flashlights, cameras, and medical devices (pacemakers, hearing aids, and shoulder massagers, etc.). Furthermore, it can be used for various military and space applications. It can also be combined with solar cells.

[0774] Example

[0775] The features of the present invention will be described in more detail below with examples and comparative examples. The materials, amounts, proportions, processing contents, and processing steps shown in the following examples can be appropriately modified without departing from the spirit of the present invention. Therefore, the scope of the present invention is not to be interpreted as limited by the specific examples shown below.

[0776] <Example 1>

[0777] Lithium compounds were obtained by ball milling Li2B4O7 (247) powder (manufactured by RARE METALLIC Co., Ltd.) using a ball mill (FRITSCH P-7) under the following conditions: 45 ml of stabilized zirconium oxide (YSZ) jar, 50 balls of stabilized zirconium oxide (YSZ) with an average particle size of 5 mm and a quantity of 50 balls, a rotation speed of 370 rpm, 1 g of LBO powder (Li2B4O7 crystals in powder form (manufactured by RARE METALLIC Co., Ltd.)), atmospheric conditions, and a ball milling time of 100 hours.

[0778] The obtained lithium compound was further ball-milled for 100 hours by adding 0.05 g of Li salt, namely Li(FSO2)2N(LiFSI). The resulting powder was then added to water at a concentration of 42% by mass and ultrasonically dispersed for 30 minutes.

[0779] Next, the obtained dispersion was transferred to a glass petri dish and dried at 120°C for 2 hours under atmospheric conditions to obtain a thin film of lithium-based solid electrolyte. The obtained film was then peeled off to obtain a powder.

[0780] The lithium-based solid electrolyte obtained above has a particle size distribution of several μm to about 10 μm, with a median particle size (D50) of 1.5 μm.

[0781] Additionally, using the lithium-based solid electrolyte obtained above, in SPring-8 BL04B2 (accelerating voltage: 61.4 keV, wavelength: X-ray total scattering measurements were performed. Samples were sealed in 2 mm or 1 mm φ KAPTON capillaries for the experiments. Furthermore, as described above, the obtained data were subjected to Fourier transform to obtain the reduced two-body distribution function.

[0782] The analysis confirmed that in the reduced two-body distribution function G(r) obtained from X-ray total scattering measurements, r is... Within this range, the peak G(r) is represented by values ​​above 1.0, and the peak is located at... The first peak and the apex have G(r) values ​​above 1.0, and the apex is located at... The second peak, and confirmed that r is greater than and The absolute value of G(r) in the following range is except for Outside of the designated area, it meets the 1.0 requirement.

[0783] The above results confirm that the lithium-based solid electrolyte obtained by adding LiFSI and dispersing it in water is amorphous. Furthermore, in the lithium-based solid electrolyte, the peaks attributed to the BO and BB distances observed in typical lithium tetraborate crystals are maintained. Typical lithium tetraborate crystals have a 1:1 structure of BO4 tetrahedra and BO3 triangles (a dual structure), and this structure is presumed to be maintained in the lithium-based solid electrolyte.

[0784] The solid-state reaction of lithium-based solid electrolyte was carried out at 120℃. 7 The full width at half maximum (FWHM²) of the peaks with chemical shifts in the range of -100 to +100 ppm obtained during Li-NMR determination, and the solid lithium-based solid electrolyte obtained above, were compared with the results obtained at 20 °C. 7 In Li-NMR measurements, the proportion of peaks with chemical shifts in the range of -100 to +100 ppm with a full width at half maximum (FWHM 1) of {(FWHM 2 / FWHM 1) × 100} is 33%.

[0785] Solid was subjected to treatment at 20℃ 7 When the first peak in the spectrum obtained during Li-NMR determination appears in the range of -100 to +100 ppm, waveform separation is performed. Then, a second peak with a full width at half maximum (FWHM) of less than 5 ppm appears in the range of chemical shift of -3 to 3 ppm. The area intensity of the second peak is 4% of the area intensity of the first peak.

[0786] Using the lithium-based solid electrolyte obtained above, and under the conditions described above, infrared absorption spectroscopy was performed. In the obtained infrared absorption spectrum, the values ​​from 3000 to 3500 cm⁻¹... -1 The maximum absorption intensity in the wavenumber region is relative to 800–1600 cm⁻¹ -1 The ratio of the maximum absorption intensity in the wavenumber region is 0.72.

[0787] In the Raman spectra of the obtained lithium-based solid electrolytes, the range is 600–850 cm⁻¹. -1 The coefficient of determination obtained by linear regression analysis based on the least squares method within the wavenumber region is 0.9974.

[0788] As described above, the mass reduction rate of the obtained lithium-based solid electrolyte when heated from 25°C to 800°C was 29.8%.

[0789] The elements in the obtained lithium-based solid electrolyte were analyzed by ICP-OES for lithium and boron, and by combustion ion chromatography (combustion IC) for fluorine and sulfur. For N, the atomic weights in the Li salt were considered and estimated from the analytical mass of sulfur. For O, the analytical masses of all elements except O were summed and the difference was calculated from the total amount of powder. The results are shown in the table below.

[0790] <Example 2>

[0791] Lithium compounds were obtained by ball milling Li2B4O7 (247) powder (manufactured by RARE METALLIC Co., Ltd.) using a ball mill (FRITSCH P-7) in the following conditions: 45 ml of stabilized zirconium oxide (YSZ) granulation balls (average particle size: 5 mm, quantity: 50 balls), 370 rpm (revolutions per minute), 1 g of LBO powder (powdered Li2B4O7 crystals (manufactured by RARE METALLIC Co., Ltd.)), atmospheric conditions, and 100 hours of ball milling time.

[0792] The obtained lithium compound was added to water at a powder concentration of 42% by mass and ultrasonically dispersed for 30 minutes.

[0793] Next, 0.05 g of Li(FSO2)2N(LiFSI) was added to the obtained dispersion, and ultrasonic dispersion was carried out for 30 minutes.

[0794] Next, the obtained dispersion was transferred to a glass petri dish and dried at 120°C for 2 hours under atmospheric conditions to obtain a thin film of a lithium-based solid electrolyte. The obtained film was then peeled off to obtain a powder. Using the obtained powder, various evaluations were performed in the same manner as in Example 1. The results are summarized in the table described below.

[0795] <Example 3>

[0796] Lithium compounds were obtained by ball milling Li₂B₄O₇(247) powder (manufactured by RARE METALLIC Co., Ltd.) using a ball mill (FRITSCH P-7). The mixture consisted of a 45 ml container of stabilized zirconium oxide (YSZ), grinding balls of stabilized zirconium oxide (YSZ) (average particle size: 5 mm, weight: 70 g), a rotation speed of 530 rpm, 4.2 g of LBO powder (powdered Li₂B₄O₇ crystals (manufactured by RARE METALLIC Co., Ltd.)), atmospheric conditions, and a ball milling time of 100 hours. The obtained lithium compounds were added to water with a powder concentration of 42% by mass and ultrasonically dispersed for 60 minutes to obtain solution 1.

[0797] Next, 4.65 g of Li(FSO2)2N(LiFSI) was added to water at a powder concentration of 87% by mass, and ultrasonically dispersed for 60 minutes to obtain solution 2.

[0798] The obtained solutions 1 and 2 were mixed and stirred with a magnetic stirrer for 60 minutes. Then, using the powder obtained by vacuum drying the dispersion for 15 hours at 40°C and 10 Pa, various evaluations were performed at atmospheric pressure in the same manner as in Example 1. The results are summarized in the table described below.

[0799] <Example 4>

[0800] Lithium compounds were obtained by ball milling Li₂B₄O₇(247) powder (manufactured by RARE METALLIC Co., Ltd.) using a ball mill (FRITSCH P-7). The mixture consisted of a 45 ml container of stabilized zirconium oxide (YSZ), grinding balls of stabilized zirconium oxide (YSZ) (average particle size: 5 mm, weight: 70 g), a rotation speed of 530 rpm, 4.2 g of LBO powder (powdered Li₂B₄O₇ crystals (manufactured by RARE METALLIC Co., Ltd.)), atmospheric conditions, and a ball milling time of 100 hours. The obtained lithium compounds were added to water with a powder concentration of 42% by mass and ultrasonically dispersed for 60 minutes to obtain solution 3.

[0801] Next, 3.67 g of Li(FSO2)2N(LiFSI) was added to water at a powder concentration of 87% by mass, and ultrasonically dispersed for 60 minutes to obtain solution 4.

[0802] Solutions 3 and 4 were mixed and stirred with a magnetic stirrer for 60 minutes. Then, using the powder obtained by vacuum drying the dispersion for 15 hours at 40°C and 10 Pa, various evaluations were performed at atmospheric pressure in the same manner as in Example 1. The results are summarized in the table described below.

[0803] <Example 5>

[0804] Lithium compounds were obtained by ball milling Li₂B₄O₇(247) powder (manufactured by RARE METALLIC Co., Ltd.) using a ball mill (FRITSCH P-7). The mixture consisted of a 45 ml container of stabilized zirconium oxide (YSZ), grinding balls of stabilized zirconium oxide (YSZ) (average particle size: 5 mm, weight: 70 g), a rotation speed of 530 rpm, 4.2 g of LBO powder (powdered Li₂B₄O₇ crystals (manufactured by RARE METALLIC Co., Ltd.)), atmospheric conditions, and a ball milling time of 100 hours. The obtained lithium compounds were added to water with a powder concentration of 42% by mass and ultrasonically dispersed for 60 minutes to obtain solution 5.

[0805] Next, 7.13 g of Li(F3CSO2)2N(LiTFSI) was added to water at a powder concentration of 87% by mass, and ultrasonically dispersed for 60 minutes to obtain solution 6.

[0806] Solutions 5 and 6 were mixed and stirred with a magnetic stirrer for 60 minutes. Then, using the powder obtained by vacuum drying the dispersion for 15 hours at 40°C and 10 Pa, various evaluations were performed at atmospheric pressure in the same manner as in Example 1. The results are summarized in the table described below.

[0807] In addition, in Example 5, the amount of carbon shown in Table 2 below was estimated from the analytical mass of sulfur, taking into account the atomic weights of the Li salt.

[0808] <Comparative Example 1>

[0809] Comparative pressed powder was obtained by pressing powdered Li₂B₄O₇ crystals (LBO powder) (manufactured by RAREMETALLIC Co., Ltd.) (crystal powder) at 27°C (room temperature) and an effective pressure of 220 MPa. The ionic conductivity of the obtained pressed powder could not be detected.

[0810] <Reference Example>

[0811] Lithium compounds were obtained by ball milling Li₂B₄O₇(LBO) powder (manufactured by RARE METALLIC Co., Ltd.) using a ball mill (FRITSCH P-7). The conditions were: 45 ml of stabilized zirconium oxide (YSZ) granulation balls (average particle size: 5 mm, quantity: 50 balls), 500 rpm (revolutions per minute), 2 g of LBO powder (powdered Li₂B₄O₇ crystals (manufactured by RARE METALLIC Co., Ltd.)), atmospheric atmosphere, and a ball milling time of 100 hours. The obtained lithium compounds were then subjected to various evaluations in the same manner as in Example 1.

[0812] The obtained lithium compound has a particle size distribution of several μm to approximately 10 μm, with a median particle size (D50) of 1.5 μm. Furthermore, the bulk elastic modulus of the obtained lithium compound is 36 GPa. In contrast, the bulk elastic modulus of the LBO powder before ball milling is 47 GPa.

[0813] The bulk modulus of the lithium compound was determined by ultrasonic attenuation. Specifically, a suspension of the lithium compound in pure water was first prepared. The lithium compound content in the suspension was set to 1.2% by mass relative to the total mass of the suspension. Next, the ultrasonic attenuation spectrum of the suspension was measured, and the bulk modulus (GPa) of the lithium compound was obtained from the fitting of the scattering attenuation theory formula. In addition, when calculating the bulk modulus, the density of a specific solid electrolyte was set to 2.3 g / mL, and the Poisson's ratio was set to 0.12 for fitting. Furthermore, the bulk modulus was calculated using equations (7), (12), and (13) described in Kohjiro Kubo et al., Ultrasonics 62 (2015) 186-194.

[0814] <Various Evaluations (Part 1)>

[0815] (Measurement of ionic conductivity)

[0816] The lithium-based solid electrolytes obtained in each embodiment were pressed into powder at 27°C (room temperature) and an effective pressure of 220 MPa to obtain pressed powder. In foil was placed on the surface and back of the obtained pressed powder, and the ionic conductivity was estimated from the analysis of the arc diameter of the Cole-Cole diagram (Nyquist plot) obtained by AC impedance measurement via two In electrodes (measurement temperature 27°C or 60°C, applied voltage 50 mV, measurement frequency range 1 Hz to 1 MHz).

[0817] (X-ray total scattering measurement)

[0818] Using the lithium-based solid electrolyte of the examples, the crystal powder of the comparative examples, and the lithium compound of the reference examples, at SPring-8BL04B2 (accelerating voltage: 61.4 keV, wavelength: X-ray total scattering measurements were performed. Samples were sealed in 2 mm or 1 mm φ KAPTON capillaries for the experiments. Furthermore, as described above, the obtained data were subjected to Fourier transform to obtain the reduced two-body distribution function.

[0819] The analysis results show that in the reduced two-body distribution function G(r) obtained from X-ray total scattering measurements, there exists a peak located at r. The first peak and the apex within the range are located at r. For the second peak within the range, the peak G(r) of the first peak and the peak G(r) of the second peak indicate that when the value is greater than 1.0, the "Short distance G(r)" column in Table 3 is set to "A", and all other cases are set to "B".

[0820] Furthermore, in Examples 1 to 4 shown in Table 3 below and Examples 8 to 12 shown in Table 6 below, the G(r) value of the peak of the first peak is 1.2 or higher.

[0821] Furthermore, in the aforementioned reduced two-body distribution function G(r), r is greater than... and For the following ranges, if the absolute value of G(r) is less than 1.0, set the "Long Distance G(r)" column in Table 3 to "A"; otherwise, set it to "B".

[0822] (X-ray diffraction measurement)

[0823] X-ray diffraction measurements were performed on the lithium-based solid electrolyte of the examples, the crystalline powder of the comparative examples, and the lithium compound of the reference examples using CuK α rays. The measurement conditions were 0.01° / spacing and 3° / min.

[0824] The measurement results are used to determine the diffraction patterns. If the condition Y is met, the result is designated as "A"; otherwise, it is designated as "B".

[0825] Furthermore, in Examples 1 to 5 shown in Table 3 and Examples 6 to 13 shown in Table 6, the first, second, third and fourth peaks are not present in the X-ray diffraction patterns, or the intensity ratio of at least one of the specific peaks selected from the first, second, third and fourth peaks is 2.0 or less.

[0826] In Table 1, the “Elemental Analysis” column indicates the molar content of each element, which sets the composition of the lithium-based solid electrolyte obtained in each embodiment as a relative value when the Li content is set to “1.00”.

[0827] In Table 2, the “Elemental Analysis” column indicates the molar content of each element, which sets the composition of the lithium-based solid electrolyte obtained in each embodiment as a relative value when the content of B is set to “4.00”.

[0828] In the table, the "Percentage of Full Horizon (%)" column indicates the percentage of lithium-based solid electrolytes produced at 120°C. 7 The full width at half maximum (FWHM) of the peaks with chemical shifts in the range of -100 to +100 ppm obtained during Li-NMR measurements is comparable to that of the solid lithium electrolyte obtained at 20 °C. 7 The percentage (%) of the full width at half maximum (FWHM) of peaks whose chemical shifts occur in the range of -100 to +100 ppm in the spectra obtained during Li-NMR determination.

[0829] In the table, the "Ratio of Area Intensity" column indicates the ratio of the area intensity of the second peak to the area intensity of the first peak described above. The "Value (%)" column indicates the specific value, and the "Range" column indicates the range to which the values ​​of each embodiment and comparative example belong according to the following benchmark (range of area intensity ratio). Additionally, in Examples 4 and 5, the "Value (%)" column does not show a value; the "Range" column indicates the range.

[0830] (Range of area intensity)

[0831] A: When the area intensity ratio is 15% or higher.

[0832] B: Cases where the area intensity ratio is 0.5% or more but less than 15%.

[0833] C: Cases where the area intensity ratio is less than 0.5%.

[0834] In the table, the "Maximum Absorption Intensity Ratio" column indicates the ratio of the maximum absorption intensity in the infrared absorption spectrum of lithium-based solid electrolytes, specifically the ratio between 3000 and 3500 cm⁻¹. -1 The maximum absorption intensity in the wavenumber region is relative to 800–1600 cm⁻¹ -1 The ratio of the maximum absorption intensities in the wavenumber region. The "Value" column indicates the specific value, and the "Range" column indicates which range the values ​​of each embodiment and comparative example belong to according to the following criteria (maximum absorption intensity ratio range). In addition, in Embodiments 4 and 5, the "Value" column does not show the value, and the "Range" column indicates which range it belongs to.

[0835] (Maximum absorption intensity ratio range)

[0836] A: When the maximum absorption intensity ratio is above 0.20

[0837] B: Case where the maximum absorption intensity ratio is less than 0.20

[0838] In the table, the column for "Maximum Absorption Intensity Ratio (N2 Atmosphere, Heated at 90℃)" indicates the infrared absorption spectrum of the lithium-based solid electrolyte after heating it at 90℃ for 5 minutes. The obtained infrared absorption spectrum shows the values ​​in the 3000–3500 cm⁻¹ range. -1 The maximum absorption intensity in the wavenumber region is relative to 800–1600 cm⁻¹ -1 The ratio of the maximum absorption intensity in the wavenumber region.

[0839] In the table, the "Coefficient of Determination" column indicates that, for Examples 1 and 2, the coefficient of determination is within the Raman spectrum at 600–850 cm⁻¹. -1 The coefficients were determined by linear regression analysis based on the least squares method in the wavenumber region.

[0840] In the table, under the column "Requirement T", cases that meet the above requirement T are marked as "A", and cases that do not meet it are marked as "B". Furthermore, in the Raman spectra of the lithium-based solid electrolytes of Examples 1-5, the values ​​specified by requirement T, within the range of 710-730 cm⁻¹, are... -1 It has a apex, and the full width of half the apex is 5cm. -1 The first peak mentioned above is between 770 and 790 cm. -1 It has a apex and a half-peak width of 5cm. -1 The second peak mentioned above is located at 1020–1040 cm⁻¹. -1 It has a apex and a half-peak width of 5cm. -1 The third peak mentioned above does not exist.

[0841] In the table, the "Mass Reduction Rate (%)" column indicates the mass reduction rate when the lithium-based solid electrolyte is heated to 800°C.

[0842] In the table, "-" indicates that the measured value is not shown.

[0843] In addition, in Examples 1 to 5, the lithium compounds obtained by ball milling Li2B4O7 (247) powder (manufactured by RARE METALLIC Co., Ltd.) all meet the requirements of S1 to S3 above.

[0844] More specifically, in Examples 1 to 5, the first to third peaks specified by requirement S2 were not present in the Raman spectra of the lithium compounds obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.).

[0845] Furthermore, in Examples 1 to 5, the X-ray diffraction patterns of lithium compounds obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.) using CuK α rays were such that the first to fourth peaks specified by requirement S3 were absent, or at least one specific peak selected from the first, second, third, and fourth peaks was present, and the intensity ratio calculated by at least one intensity measurement method of the specific peaks was 2.0 or less.

[0846] Furthermore, in Examples 1 to 5, the lithium compounds obtained by ball milling Li2B4O7 (247) powder (manufactured by RARE METALLIC Co., Ltd.) satisfy requirement W.

[0847] Furthermore, in Examples 1-5, the lithium compounds obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.) satisfy requirement V. More specifically, in Examples 1-5, the X-ray diffraction patterns obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.) using CuK α rays do not contain peaks 1 to 4 as specified in requirement S3, or at least one specific peak selected from peak 1, peak 2, peak 3, and peak 4 is present, and the intensity ratio of at least one of the specific peaks calculated by the intensity measurement method is 2.0 or less.

[0848] Furthermore, in Examples 1-5, the lithium compounds obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.) satisfied requirement T2. More specifically, in Examples 1-5, the first to third peaks specified by requirement T2 were absent from the Raman spectra of the lithium compounds obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.).

[0849] [Table 1]

[0850]

[0851] [Table 2]

[0852]

[0853] [Table 3]

[0854]

[0855] As shown in the table above, the lithium-based solid electrolyte of the present invention exhibits the desired properties. In particular, in the invention described in Patent Document 1, the ionic conductivity is 10... -5 S·cm -1 Relatively speaking, the ionic conductivity of the present invention is confirmed to be superior.

[0856] As shown in Table 2, in Example 3, a higher Li content was confirmed.

[0857] The reason for the increase in Li content is speculated as follows: In Example 3, a method was implemented to mix an aqueous solution containing a mechanically ground lithium compound and an aqueous solution containing a lithium salt (method 3 in step 2B above). Since this method can increase the mixing amount of Li(FSO2)2N (LiFSI), the amount of Li obtained in the lithium-based solid electrolyte increases. Furthermore, in Example 3, it was confirmed that the ionic conductivity was further improved. The reason for the increase in ionic conductivity is speculated as follows: Due to the increase in the Li composition ratio (content ratio), the increased Li includes highly mobile Li, thus increasing the amount of highly mobile Li as a whole.

[0858] Furthermore, as shown in the "Maximum Absorption Ratio" and "Maximum Absorption Ratio (N2 Atmosphere, Heated at 90°C)" columns of Table 3, in Example 3, the maximum absorption ratio was 3000–3500 cm⁻¹ through heat treatment. -1 The maximum absorption intensity in the wavenumber region is relative to 800–1600 cm⁻¹ -1 The ratio of maximum absorption intensity in the wavenumber region decreases. This is presumably due to the evaporation of free water contained in the lithium-based solid electrolyte.

[0859] The reduced two-body distribution function G(r) obtained from the X-ray total scattering measurement of the crystal powder in Comparative Example 1 has a peak located at... The first peak (corresponding to near BO) and the summit are located The second peak (corresponding to near BB), the peaks of the first and second peaks have G(r) values ​​above 1.0 (reference). Figure 12 Furthermore, there exists a peak located at... and The peaks, each with a peak G(r) greater than 1.0 (reference). Figure 12 ).

[0860] In contrast, the reductive two-body distribution function G(r) obtained from X-ray total scattering measurements of the lithium compound in the reference example has a peak located at... The first peak (corresponding to near BO) and the summit are located The second peak (corresponding to near BB) has a G(r) greater than 1.0 for the peaks of the first and second peaks. On the other hand, r is greater than... Head. In the following range, the absolute value of G(r) is less than 1.0.

[0861] These results confirm that mechanical grinding can achieve a r greater than [value missing]. and The peaks of the long-distance ordered structure in the following range are reduced. On the other hand, after mechanical polishing, the peaks attributed to the BO-B and BB-B distances observed in typical lithium tetraborate crystals are maintained. Based on this result, it is believed that the structure (double structure) in which BO4 tetrahedra and BO3 triangles exist in a 1:1 ratio contained in typical lithium tetraborate crystals is maintained during mechanical polishing.

[0862] Figure 13 The X-ray diffraction pattern of the crystalline powder of Comparative Example 1 is shown below. Figure 13 As shown, in Comparative Example 1, condition Y is not satisfied, and several narrow peaks were observed. More specifically, the strongest peak corresponding to the (1, 1, 2) plane was observed at 21.78° at the 2θ value. Other major diffraction peaks include a peak corresponding to the (2, 0, 2) plane at 25.54°, a peak corresponding to the (2, 1, 3) plane at 33.58°, and a peak corresponding to the (3, 1, 2) plane at 34.62°; these three peaks have approximately the same intensity. These peaks originate from the crystal composition.

[0863] In contrast, Figure 14 The X-ray diffraction pattern of the lithium-based solid electrolyte of Example 3 is shown in the figure. Figure 14 As shown, in Example 3, even if the strength ratio specified in requirement Y above, which is 5.0, is set to 2.0, the requirement is still met. Figure 13 It can be seen that the crystal components present by mechanical grinding are amorphized, and the sharp peaks originating from lithium tetraborate crystals disappear and become broad.

[0864] <Evaluation (Part 2)>

[0865] The lithium-based solid electrolyte powder (particles) (10 mm φ, 0.9 mm t) obtained in Example 3 was vacuum dried under a pressure of 60 MPa and at 27 °C. The pressure change and ionic conductivity during vacuum drying time were evaluated.

[0866] In addition, regarding the preparation method of the pressed powder and the evaluation of its ionic conductivity, except that the In electrode described in the above-mentioned <Various Evaluations (1)> (Ionic Conductivity Measurement) was changed to a Ti electrode, the powder was prepared and evaluated using the same method. The results are shown in Table 4 below.

[0867] [Table 4]

[0868]

[0869] Regarding the lithium-based solid electrolyte of Example 3, it is believed that in the infrared absorption spectrum, due to the 3000–3500 cm⁻¹... -1 The increased OH stretching peak indicates the presence of a large number of OH groups or water. Furthermore, regarding water, it is speculated that free water or water in a different state exists.

[0870] In the above evaluation, in order to confirm the existence of substances with good ionic conductivity in addition to free water, the particles were first dried under conditions where free water was assumed to evaporate, and then dried under conditions where the intensity was further increased, thereby evaluating the ionic conductivity at each stage.

[0871] As shown in Table 4, with a drying time of 5 minutes and a pressure of 200 Pa, it is assumed that the free water is in a vaporized state. However, it can be seen that even with an ionic conductivity of 3.8 × 10⁻⁶, the water remains in a vaporized state. -3 At a pressure of 15 Pa and a drying time of 1080 minutes, the ionic conductivity was also 5.7 × 10⁻⁶ S / cm. -4 The S / cm concentration indicates the presence of a substance with good ionic conductivity, in addition to free water. Although the exact nature of this substance is unclear, it is presumed to be water in a different state than free water.

[0872] Furthermore, although the phenomena produced during the drying process are not yet clear, as shown in Table 4, it is speculated that the drying time is 50 minutes and the pressure is 10 Pa. Under these conditions, water in a different state from free water remains, and this water gradually separates. In addition, it is speculated that the drying time is 1080 minutes and the pressure is 15 Pa. There are two states of water in a different state from free water, and water with more volatile properties remains.

[0873] The above results suggest that, even after prolonged drying time, the excellent ionic conductivity indicates the existence of water in lithium-based solid electrolytes in a state different from that of free water with good ionic conductivity.

[0874] <Example 6>

[0875] Lithium compounds were obtained by ball milling Li₂B₄O₇(247) powder (manufactured by RARE METALLIC Co., Ltd.) using a ball mill (FRITSCH P-7). The mixture consisted of: a container of stabilized zirconium oxide (YSZ) (45 ml), grinding balls of stabilized zirconium oxide (YSZ) (average particle size: 5 mm, weight: 70 g), a rotation speed of 530 rpm, 4.2 g of LBO powder (powdered Li₂B₄O₇ crystals (manufactured by RARE METALLIC Co., Ltd.)), atmospheric conditions, and a ball milling time of 100 hours. The obtained lithium compounds were added to water with a powder concentration of 42% by mass and ultrasonically dispersed for 60 minutes to obtain solution 7.

[0876] Next, 7.12 g of Li(F3CSO2)2N(LiTFSI) was added to water at a powder concentration of 87% by mass, and ultrasonically dispersed for 60 minutes to obtain solution 8.

[0877] The obtained solutions 7 and 8 were mixed and stirred with a magnetic stirrer for 60 minutes. Then, using the lithium-based solid electrolyte obtained by vacuum drying the obtained dispersion at 40°C and 10 Pa for 15 hours, various evaluations were performed under atmospheric conditions in the same manner as in Example 1.

[0878] <Example 7>

[0879] Except for changing the contents of water and Li(F3CSO2)2N(LiTFSI) in the obtained lithium-based solid electrolyte to the amounts recorded in the table below, the lithium-based solid electrolyte was obtained by the same method as in Example 6, and various evaluations were performed under atmospheric conditions in the same manner as in Example 1.

[0880] <Examples 8-13>

[0881] Except for changing Li(F3CSO2)2N(LiTFSI) to Li(FSO2)2N(LiFSI) and changing the content of water and Li(FSO2)2N(LiFSI) in the obtained lithium-based solid electrolyte to the amounts recorded in the table below, the lithium-based solid electrolyte was obtained by the same method as in Example 6, and various evaluations were performed under atmospheric conditions in the same manner as in Example 1.

[0882] In Table 5, the columns for "BM-LBO247", "Li salt", and "water" indicate the relative molar ratios of the components in the powders obtained in each embodiment and reference example. Specifically, "BM-LBO247" represents ball-milled Li2B4O7, and "Li salt" represents the lithium salts (Li(F3CSO2)2N (LiTFSI) and Li(FSO2)2N (LiFSI)) used in each embodiment. The table shows the relative molar ratios of the components when the molar amount of BM-LBO247 is set to 1. For example, in the powder obtained in Example 6, the molar ratio of Li salt to BM-LBO247 is 1, and the molar ratio of water to BM-LBO247 is 12.

[0883] In addition, the above molar ratio is calculated using the following method.

[0884] Regarding the analysis of each element in the obtained powder, lithium and boron were quantitatively analyzed by ICP-OES, and fluorine and sulfur were quantitatively analyzed by combustion ion chromatography (combustion IC). For N, the analysis mass of sulfur was estimated considering the atomic weights of the Li salts. For O, the analysis masses of all elements except O were added together, and the difference was calculated as the total amount of powder. Furthermore, in Examples 6 and 7, the carbon content was estimated from the analysis mass of sulfur, taking into account the atomic weights of the Li salts.

[0885] The molar ratio of BM-LB0247 to Li salt in the powder is calculated from the molar ratio of elements present only in BM-LB0247 (e.g., B) to elements present only in Li salt (e.g., a specific element). Furthermore, the molar ratio of BM-LB0247 to water is calculated by subtracting the molar ratio of BM-LB0247 and the molar ratio of O contained in the Li salt from the molar ratio of O in the powder, and then using the obtained molar amount of O from water and the molar amount of BM-LB0247.

[0886] In addition, in Examples 6 to 13, the lithium compounds obtained by ball milling Li2B4O7 (247) powder (manufactured by RARE METALLIC Co., Ltd.) all meet the requirements of S1 to S3 above.

[0887] More specifically, in Examples 6 to 13, the first to third peaks specified by requirement S2 were not present in the Raman spectra of the lithium compounds obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.).

[0888] Furthermore, in Examples 6 to 13, the X-ray diffraction patterns of lithium compounds obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.) using CuK α rays were such that the first to fourth peaks specified by requirement S3 were absent, or at least one specific peak selected from the first, second, third and fourth peaks was present, and the intensity ratio calculated by at least one intensity measurement method of the specific peak was 2.0 or less.

[0889] Furthermore, in Examples 6 to 13, the lithium compounds obtained by ball milling Li2B4O7 (247) powder (manufactured by RARE METALLIC Co., Ltd.) satisfy requirement W.

[0890] Furthermore, in Examples 6-13, the lithium compounds obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.) satisfy requirement V. More specifically, in Examples 6-13, the X-ray diffraction patterns obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.) using CuK α rays do not contain peaks 1 to 4 as specified in requirement S3, or at least one specific peak selected from peak 1, peak 2, peak 3, and peak 4 is present, and the intensity ratio calculated by at least one intensity measurement method of the specific peak is 2.0 or less.

[0891] Furthermore, in Examples 6-13, the lithium compounds obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.) satisfied requirement T2. More specifically, in Examples 6-13, the Raman spectra of the lithium compounds obtained by ball milling Li2B4O7(247) powder (manufactured by RARE METALLIC Co., Ltd.) did not contain the first to third peaks specified by requirement T2.

[0892] Furthermore, in the Raman spectra of the lithium-based solid electrolytes of Examples 6 to 13, the first to third peaks specified by requirement T are not present.

[0893] [Table 5]

[0894]

[0895] [Table 6]

[0896]

[0897] As shown in the table above, the lithium-based solid electrolyte of the present invention exhibits the desired performance.

[0898] Furthermore, except that LiB3O5 was used instead of Li2B4O7 (247) powder used in Example 3, a lithium-based solid electrolyte was prepared according to the same steps as in Example 3.

[0899] In addition, X-ray total scattering measurements were performed on lithium-based solid electrolytes obtained by replacing Li2B4O7 (247) powder with ball-milled LiB3O5 and LiB3O5, and the results confirmed that the above-mentioned requirements X2 and X5 were satisfied respectively.

[0900] Furthermore, in addition to using Li3B 11 O 18 A lithium-based solid electrolyte was prepared following the same steps as in Example 3, except that the Li2B4O7(247) powder used in Example 3 was substituted.

[0901] In addition, Li3B that had been ball-milled was used. 11 O 18 and Li3B 11 O 18 X-ray total scattering analysis of the lithium-based solid electrolyte obtained in place of Li2B4O7(247) powder confirmed that it met the above-mentioned requirements X3 and X5 respectively.

[0902] Furthermore, in addition to using Li3B7O 12 A lithium-based solid electrolyte was prepared following the same steps as in Example 3, except that the Li2B4O7(247) powder used in Example 3 was substituted.

[0903] In addition, Li3B7O that had been ball-milled was used. 12 and Li3B7O 12 X-ray total scattering analysis of the lithium-based solid electrolyte obtained in place of Li2B4O7(247) powder confirmed that it met the above-mentioned requirements X4 and X5 respectively.

[0904] Furthermore, in the X-ray diffraction patterns obtained from X-ray diffraction using CuK α rays, the lithium-based solid electrolytes obtained using ball-milled LiB3O5 and LiB3O5 respectively satisfy the above-mentioned requirements Y2 and Y5.

[0905] Furthermore, more specifically, in the X-ray diffraction pattern of the lithium-based solid electrolyte obtained by using the ball-milled LiB3O5 and LiB3O5 described above, peaks 1 to 4 as specified by requirements Y2 and Y5 are absent, or at least one specific peak selected from peaks 1, 2, 3 and 4 is present, and the intensity ratio calculated by at least one intensity measurement method of the specific peak is 2.0 or less.

[0906] In the X-ray diffraction pattern obtained using CuK α rays, ball-milled Li3B was used. 11 O 18 and Li3B 11 O 18 The obtained lithium-based solid electrolytes satisfy the above-mentioned requirements Y3 and Y6 respectively.

[0907] Furthermore, more specifically, when using Li3B that has undergone the aforementioned ball milling treatment... 11 O 18 and Li3B 11 O 18 In the X-ray diffraction pattern of the obtained lithium-based solid electrolyte, the first to fourth peaks as specified by the above-mentioned requirements Y3 and Y6 are not present, or at least one specific peak selected from the first, second, third and fourth peaks is present, and the intensity ratio calculated by at least one intensity measurement method of the specific peak is 2.0 or less.

[0908] Using ball-milled Li3B7O 12 and Li3B7O 12 The obtained lithium-based solid electrolyte, in the X-ray diffraction pattern obtained by using CuK α rays, satisfies the above-mentioned requirements Y4 and Y7 respectively.

[0909] Furthermore, more specifically, when using Li3B7O that has undergone the aforementioned ball milling treatment... 12 and Li3B7O 12 In the X-ray diffraction pattern of the obtained lithium-based solid electrolyte, peaks 1 to 4 as specified by the above-mentioned requirements Y4 and Y7 are not present, or at least one specific peak selected from peaks 1, 2, 3 and 4 is present, and the intensity ratio calculated by at least one intensity measurement method of the specific peak is 2.0 or less.

[0910] Symbol Explanation

[0911] 1-Negative electrode current collector, 2-Negative electrode active material layer, 3-Solid electrolyte layer, 4-Positive electrode active material layer, 5-Positive electrode current collector, 6-Working part, 10-All-solid-state lithium-ion secondary battery.

Claims

1. A lithium-based solid electrolyte comprising amorphous lithium tetraborate, water, and a lithium salt, wherein the molar ratio of the lithium salt to the lithium tetraborate is 0.001–1.5, and the molar ratio of water to the lithium tetraborate is 3–15, and solid electrolyte testing was performed at 20°C. 7 When the first peak in the spectrum obtained during Li-NMR determination appears in the range of -100 to +100 ppm, waveform separation is performed. Then, a second peak with a full width at half maximum (FWHM) of less than 5 ppm appears in the range of chemical shift of -3 to 3 ppm. The area intensity of the second peak is more than 15% of the area intensity of the first peak.

2. A lithium-based solid electrolyte comprising mechanically ground lithium tetraborate, water, and a lithium salt, wherein the molar ratio of the lithium salt to the lithium tetraborate is 0.001–1.5, and the molar ratio of water to the lithium tetraborate is 3–15, and the electrolyte has been subjected to solid-state treatment at 20°C. 7 When the first peak in the spectrum obtained during Li-NMR determination appears in the range of -100 to +100 ppm, waveform separation is performed. Then, a second peak with a full width at half maximum (FWHM) of less than 5 ppm appears in the range of chemical shift of -3 to 3 ppm. The area intensity of the second peak is more than 15% of the area intensity of the first peak.

3. A lithium-based solid electrolyte comprising amorphous LiB3O5 and Li3B 11 O 18 Or Li3B7O 12 Water and lithium salts were subjected to solid-state reaction at 20°C. 7 When the first peak in the spectrum obtained during Li-NMR determination appears in the range of -100 to +100 ppm, waveform separation is performed. Then, a second peak with a full width at half maximum (FWHM) of less than 5 ppm appears in the range of chemical shift of -3 to 3 ppm. The area intensity of the second peak is more than 15% of the area intensity of the first peak.

4. The lithium-based solid electrolyte according to any one of claims 1 to 3, wherein, The lithium salt is the compound represented by formula (1). Formula (1) LiN(R f1 SO2)(R f2 SO2) R f1 and R f2 Each can be used to represent a fluorine atom or a perfluoroalkyl group independently.

5. A lithium-based solid electrolyte, wherein, The lithium-based solid electrolyte contains Li, B, and O. The lithium-based solid electrolyte also contains two or more specific elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H, and N. The molar ratio of B to Li is greater than 1.50 and less than 2.

43. The molar ratio of O to Li is greater than 2.34 and less than 6.

86. The molar ratio of each of the specific elements relative to Li is greater than 0.001 and less than 0.

17. Solid was subjected to treatment at 20℃ 7 When the first peak in the spectrum obtained during Li-NMR determination appears in the range of -100 to +100 ppm, waveform separation is performed. Then, a second peak with a full width at half maximum (FWHM) of less than 5 ppm appears in the range of chemical shift of -3 to 3 ppm. The area intensity of the second peak is more than 15% of the area intensity of the first peak.

6. A lithium-based solid electrolyte, wherein, The lithium-based solid electrolyte contains Li, B, and O. The lithium-based solid electrolyte also contains two or more specific elements selected from Group 4, Group 15, Group 16, Group 17 of the periodic table, Si, C, Sc, Y, and H. When the molar amount of B in the lithium-based solid electrolyte is set to 4.00 to represent the molar amounts of Li, O, and the specific element, The molar amount of Li is 1.58–3.

49. The molar amount of O is 6.23–25.

00. The molar amounts of the specific elements range from 0.001 to 10.

00. Solid was subjected to treatment at 20℃ 7 When the first peak in the spectrum obtained during Li-NMR determination appears in the range of -100 to +100 ppm, waveform separation is performed. Then, a second peak with a full width at half maximum (FWHM) of less than 5 ppm appears in the range of chemical shift of -3 to 3 ppm. The area intensity of the second peak is more than 15% of the area intensity of the first peak.

7. The lithium-based solid electrolyte according to any one of claims 1 to 3, 5 and 6, wherein, In the infrared absorption spectrum, 3000 cm⁻¹ -1 ~3500cm -1 The maximum absorption intensity in the wavenumber region relative to 800 cm⁻¹ -1 ~1600cm -1 The ratio of the maximum absorption intensity in the wavenumber region is more than 1 / 5.

8. A lithium-based solid electrolyte comprising Li, B, and O, satisfying any one of requirements X to Z, and subjected to solid-state testing at 20°C. 7 When performing Li-NMR measurements, the first peak appearing in the range of -100 to +100 ppm in the obtained spectrum is waveform separated. A second peak with a full width at half maximum (FWHM) of less than 5 ppm exists in the range of -3 to 3 ppm. The area intensity of the second peak is at least 15% of the area intensity of the first peak. Requirement X: The reduced-dimer distribution function G(r) obtained from X-ray total scattering measurements of the lithium-based solid electrolyte contains a first peak with a peak value in the range of r = 1.43 ± 0.2 Å and a second peak with a peak value in the range of r = 2.40 ± 0.2 Å. The G(r) value of the first peak is greater than 1.0, and the G(r) value of the second peak is greater than 0.

8. Requirement Y: In the X-ray diffraction pattern obtained from the X-ray diffraction measurement using CuKα rays of the lithium-based solid electrolyte, the following peaks are absent: a first peak with a peak value between 21.6° and 22.0° and a full width at half maximum (FWHM) of less than 0.65°; a second peak with a peak value between 25.4° and 25.8° and a FWHM of less than 0.65°; a third peak with a peak value between 33.4° and 33.8° and a FWHM of less than 0.65°; and a fourth peak with a peak value between 34.4° and 34.8° and a FWHM of less than 0.65°. In the X-ray diffraction pattern, if at least one specific peak selected from the first peak, the second peak, the third peak, and the fourth peak exists, and the intensity ratio of at least one of the specific peaks, calculated by the following intensity measurement method, is 5.0 or less, Intensity measurement method: Calculate the average intensity 1 in the range of +0.45° to +0.55° from the diffraction angle 2θ of the peak of the specific peak; calculate the average intensity 2 in the range of -0.55° to -0.45° from the diffraction angle 2θ of the peak of the specific peak; calculate the arithmetic mean of the average intensity 1 and the average intensity 2; and define the ratio of the peak intensity of the peak of the specific peak to the arithmetic mean as the intensity ratio. Requirement Z: In the infrared absorption spectrum of the lithium-based solid electrolyte, at 3000 cm⁻¹ -1 ~3500cm -1 The maximum absorption intensity in the wavenumber region relative to 800 cm⁻¹ -1 ~1600cm -1 The ratio of the maximum absorption intensity in the wavenumber region is more than 1 / 5.

9. The lithium-based solid electrolyte according to claim 8, further comprising one or more specific elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H and N.

10. The lithium-based solid electrolyte according to any one of claims 1 to 3, 5, 6 and 8, wherein, Solid was subjected to treatment at 120℃ 7 The full width at half maximum (FWHM) of peaks with chemical shifts in the range of -100 ppm to +100 ppm obtained during Li-NMR measurements is relative to the values ​​obtained during solid-state ... 7 In Li-NMR measurements, the proportion of the full width at half maximum (FWHM) of peaks with chemical shifts in the range of -100 ppm to +100 ppm is less than 50%.

11. The lithium-based solid electrolyte according to claim 5, wherein, At 600 cm⁻¹ in the Raman spectrum -1 ~850cm -1 The coefficient of determination obtained by linear regression analysis based on the least squares method within the wavenumber region is above 0.9400.

12. The lithium-based solid electrolyte according to claim 5, wherein, The mass reduction rate when heated to 800°C is 20% to 40% by mass.

13. A method for manufacturing a lithium-based solid electrolyte, wherein the method is the same as that for manufacturing a lithium-based solid electrolyte according to any one of claims 1 to 12. The method for manufacturing the lithium-based solid electrolyte includes: Step 1: Mechanical grinding is performed on lithium oxides containing Li and B; Step 2 involves mixing the product obtained in step 1 with water; and Step 3 involves removing water from the dispersion obtained in step 2 to obtain a lithium-based solid electrolyte. The method for manufacturing the lithium-based solid electrolyte satisfies any one of the following requirements 1 to 3. Requirement 1: The mechanical grinding process of step 1 is performed in the presence of a specific element source containing two or more elements selected from F, Cl, Br, I, S, P, Si, Se, Te, C, Sb, As, Sc, Y, Zr, Ti, Hf, H, and N. Requirement 2: In step 2, the product, water, and the specific element source are mixed. Requirement 3: In step 3, the product obtained by removing water from the dispersion obtained in step 2 is mixed with the specific element source to obtain the lithium-based solid electrolyte.

14. The method for manufacturing a lithium-based solid electrolyte according to claim 13, wherein requirement 1 is satisfied. Prior to step 1, in the absence of the specific element source, there is a step 0 in which a lithium oxide containing Li and B is mechanically ground.

15. A modified positive electrode active material, comprising a positive electrode active material and a coating layer disposed on the positive electrode active material. The coating layer comprises a lithium-based solid electrolyte as described in any one of claims 1 to 12.

16. A modified negative electrode active material, comprising a negative electrode active material and a coating layer disposed on the negative electrode active material. The coating layer comprises a lithium-based solid electrolyte as described in any one of claims 1 to 12.

17. An all-solid-state secondary battery, comprising sequentially a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer. At least one of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer comprises a lithium-based solid electrolyte as described in any one of claims 1 to 12.

18. An electrode sheet for an all-solid-state secondary battery, comprising a lithium-based solid electrolyte as described in any one of claims 1 to 12.

19. A solid electrolyte sheet comprising the lithium-based solid electrolyte according to any one of claims 1 to 12.

20. An electrode for an all-solid-state secondary battery, comprising: The active material layer comprises the active material and the lithium-based solid electrolyte according to any one of claims 1 to 12; and Current collector.

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