Solid electrolyte, method for manufacturing solid electrolyte, and battery

Abstract

The solid electrolyte contains: a first element group which is one or more alkali metal elements selected from the group consisting of Li, Na, and K; a second element group which is one or more elements selected from metal elements and semi-metal elements that are trivalent cations; a third element group which is one or more halogen elements selected from the group consisting of F, Cl, Br, and I; and a hydroxyl group.

Description

Technical Field

[0001] This invention relates to solid electrolytes and batteries.

[0002] [Reference to relevant applications]

[0003] This application claims priority to international patent application PCT / JP2023 / 045959, filed on December 21, 2023, the entire disclosure of which is incorporated herein by reference. Background Technology

[0004] In recent years, with the development of portable devices such as personal computers and mobile phones, the demand for batteries as their power source has increased significantly. In batteries used for such applications, organic electrolytes, obtained by dissolving the electrolyte in flammable organic solvents, have traditionally been used as the medium for ion movement. However, such batteries require structures to ensure the safety of the organic electrolyte, increasing manufacturing costs.

[0005] To eliminate the aforementioned problems, all-solid-state batteries are being developed that use solid electrolytes, which are non-flammable materials, instead of organic electrolytes to ensure inherent safety. Among solid electrolytes, sulfide-based solid electrolytes are known. However, sulfide-based solid electrolytes produce hydrogen sulfide gas when they react with water. On the other hand, oxide-based solid electrolytes that do not produce gases like hydrogen sulfide are also under extensive development; however, the lithium-ion conductivity of these materials is lower than that of sulfide-based electrolytes, making it difficult to increase battery output power (extract high current).

[0006] The book "Li" by R. Miyazaki and H. Maekawa + A solid electrolyte with lithium-ion conductivity was proposed in "Ion Conduction of Li3AlF6 Mechanically Milled with LiCl" (ECS Electrochemistry Letters, 2012, Vol. 1, No. 6, pp. A87-A89) (Reference 1), in which the lithium-ion conductivity was improved by mechanically milling Li3AlF6 and LiCl. It should be noted that international publication WO2021 / 261558 (Reference 2) discloses a solid electrolyte with the formula Li2ZrOHCl5.

[0007] There has been a continuous search for ways to improve the ionic conductivity of solid electrolytes, and there has been a demand for new solid electrolytes with high ionic conductivity. Summary of the Invention

[0008] This invention relates to solid electrolytes, and its main objective is to provide solid electrolytes with high ionic conductivity.

[0009] Scheme 1 of the present invention is a solid electrolyte comprising: a first element group, wherein the first element group is one or more alkali metal elements selected from the group consisting of Li, Na and K; a second element group, wherein the second element group is one or more elements that are trivalent cations selected from metal elements and half-metal elements; a third element group, wherein the third element group is one or more halogen elements selected from the group consisting of F, Cl, Br and I; and a hydroxyl group.

[0010] According to the present invention, a solid electrolyte with high ionic conductivity can be provided.

[0011] In Scheme 2 of the present invention, based on the solid electrolyte of Scheme 1, the second element group includes Al or Ga.

[0012] Scheme 3 of the present invention is based on the solid electrolyte of Scheme 1 (which may be Scheme 1 or 2), wherein the elements contained in the second element group, excluding alkali metal elements and half-metal elements, are 50 mol% or more.

[0013] Scheme 4 of the present invention is based on the solid electrolyte of Scheme 2, wherein the second element group includes Al.

[0014] In Scheme 5 of the present invention, based on the solid electrolyte of Scheme 1 (which may be any one of Schemes 1 to 4), the third element group includes F or Cl.

[0015] Scheme 6 of the present invention, based on the solid electrolyte of Scheme 1 (which can be any one of Schemes 1 to 5), expresses the first element group as Mα, the second element group as Mβ, and the third element group as X, with the composition formula being Mα. a Mβ b X c (OH) d It means that the following conditions are met: a + 3 × b = c + d, 2.7 < a < 3.3, 0 < b < 1, 0 < c < 6, and 0 < d < 6.

[0016] Based on the solid electrolyte of Scheme 1 (which can be any one of Schemes 1 to 6), Scheme 7 of the present invention has peaks in the diffraction pattern obtained by X-ray diffraction using CuKα rays in the range of 2θ being 21-24°, 32-34°, and 35.5-37.5°.

[0017] Based on the solid electrolyte of Scheme 4, Scheme 8 of the present invention has no peaks in the range of 2θ being 24 to 26° in the diffraction pattern obtained by X-ray diffraction using CuKα rays.

[0018] Scheme 9 of the present invention, based on the solid electrolyte of Scheme 4 (which can be Scheme 4 or 8), exhibits Raman spectra at 470 cm⁻¹. －1 Above and 570cm －1 Below and 720cm －1 Above and 820cm －1 The following peak appears.

[0019] Scheme 10 of the present invention is based on the solid electrolyte of Scheme 4 (which may be Scheme 4, 8 or 9), wherein the coordination number of Al is 4 for more than 60 mol%.

[0020] The present invention also relates to batteries.

[0021] Solution 11 of the present invention is a battery comprising: a positive electrode; a negative electrode; and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein the solid electrolyte of any one of solutions 1 to 10 is included in at least one of the positive electrode, the negative electrode and the solid electrolyte layer.

[0022] The present invention also relates to a method for manufacturing a solid electrolyte.

[0023] Scheme 12 of the present invention is a method for manufacturing a solid electrolyte, comprising the following steps: a) preparing a first material, wherein the first material is a compound comprising an element group consisting of one or more trivalent elements selected from metallic elements and half-metallic elements and an element group consisting of one or more halogen elements selected from the group consisting of F, Cl, Br and I; b) preparing a second material, wherein the second material is a hydroxide comprising an element group consisting of one or more alkali metal elements selected from the group consisting of Li, Na and K; c) subjecting a mixture comprising the first material and the second material to mechanochemical treatment; and d) heating the mechanochemically treated mixture at 40°C or higher for 30 minutes or more and 24 hours or less, thereby obtaining a solid electrolyte.

[0024] Based on the solid electrolyte manufacturing method of Scheme 12, Scheme 13 of the present invention further includes the following step before step c): d) preparing a third material, wherein the third material is a compound consisting of an element group consisting of one or more alkali metal elements selected from the group consisting of Li, Na and K and an element group consisting of one or more halogen elements selected from the group consisting of F, Cl, Br and I, and in step c), a mixture comprising the first material, the second material and the third material is subjected to mechanochemical treatment.

[0025] In embodiment 14 of the present invention, based on the solid electrolyte manufacturing method of embodiment 12 or 13, the mixture that has undergone mechanochemical treatment is pressurized at a pressure of 1 MPa or more and 500 MPa or less in step d).

[0026] The above-mentioned objectives, as well as other objectives, features, solutions, and advantages, will become clear from the following detailed description of the invention with reference to the accompanying drawings. Attached Figure Description

[0027] Figure 1 This is a longitudinal cross-sectional view of an all-solid-state secondary battery.

[0028] Figure 2 This is a diagram showing the manufacturing process of solid electrolytes.

[0029] Figure 3 This is a diagram showing how a solid electrolyte is pressed and molded.

[0030] Figure 4 This is a diagram showing the XRD patterns in Experimental Examples 1, 2, and 5.

[0031] Figure 5 The figure shows the infrared spectrophotometry results in Experiment Examples 1 and 2.

[0032] Figure 6 This is a diagram showing how the potential window is measured.

[0033] Figure 7 This is a graph showing the measurement results obtained using cyclic voltammetry.

[0034] Figure 8 This is a diagram showing the Raman spectrum.

[0035] Figure 9 This is a graph showing the NMR spectrum.

[0036] Figure 10 This is a graph showing the discharge curve of the all-solid-state battery (1).

[0037] Figure 11 This is a graph showing the discharge curve of the all-solid-state battery (2). Detailed Implementation

[0038] Figure 1 This is a longitudinal cross-sectional view of the all-solid-state secondary battery 1. The all-solid-state secondary battery 1... Figure 1 Starting from the top, the electrode comprises a positive electrode 11, a solid electrolyte layer 13, and a negative electrode 12. Specifically, the solid electrolyte layer 13 is located between the positive electrode 11 and the negative electrode 12. The solid electrolyte layer 13 also serves as a separator layer. The positive electrode 11 includes a current collector 111 and a positive electrode layer 112. The positive electrode layer 112 contains a positive electrode active material. The negative electrode 12 includes a current collector 121 and a negative electrode layer 122. The negative electrode layer 122 contains a negative electrode active material.

[0039] The positive electrode active material of the positive electrode layer 112 preferably comprises a lithium composite oxide. The preferred positive electrode active material is a lithium composite oxide with a layered rock salt structure, such as NCM (Li(Ni,Co,Mn)O2). Other lithium composite oxides can also be used, such as NCA (Li(Ni,Co,Al)O2) or LCO (LiCoO2) with a layered rock salt structure, or LNMO (LiNiO2) with a spinel-type structure. 0.5 Mn 1.5 O4), LFP (LiFePO4) with an olivine-type structure, etc. In addition to the positive electrode active material, the positive electrode layer 112 also contains the solid electrolyte and electron conduction aids (such as carbon black), which will be described later. In this embodiment, the positive electrode layer 112 is obtained by integrating these materials using pressure and heating.

[0040] Examples of negative electrode active materials used as negative electrode layer 122 include: LTO (Li4Ti5O) 12 Compounds such as NTO (Nb2TiO7), TiO2 (titanium oxide), graphite, and SiO (silicon monoxide) are used. In addition to the negative electrode active material, the negative electrode layer 122 also contains the solid electrolyte described later. The negative electrode layer 122 may further contain electron conduction aids (such as carbon black). In this embodiment, the negative electrode layer 122 is obtained by integrating these materials using pressure and heating.

[0041] The composition and materials of the positive electrode 11 and negative electrode 12 of the all-solid secondary battery 1 are not limited to the above-mentioned composition and materials, and various other compositions and materials can be used.

[0042] The solid electrolyte layer 13 is composed of, or contains, an ion-conducting material that serves as a solid electrolyte. The solid electrolyte comprises: a first element group consisting of one or more alkali metal elements selected from the group consisting of Li (lithium), Na (sodium), and K (potassium); a second element group consisting of one or more metallic and half-metallic elements selected from the group consisting of metals other than Li, Na, K, Zr (zirconium), and Mg (magnesium); a third element group consisting of one or more halogen elements selected from the group consisting of F (fluorine), Cl (chlorine), Br (bromine), and I (iodine); and OH (hydroxyl). Thus, a novel solid electrolyte with high ion conductivity can be provided. Specifically, a conductivity of 1.0 × 10⁻⁶ at room temperature is obtained. －5 The ionic conductivity is above S / cm. In addition, the solid electrolyte has a wide potential window and good moisture resistance.

[0043] Preferably, the second element group consists of one or more trivalent cations selected from metallic and half-metallic elements, and more preferably, the second element group includes Al. Preferably, in the solid electrolyte, the elements contained in the second element group, excluding alkali metals and half-metallic elements, account for 50 mol% or more.

[0044] In this specification, the half-metal elements are boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te). The metallic elements are elements contained in Groups 1 to 12 of the periodic table, excluding hydrogen, and elements contained in Groups 13 to 16, excluding the aforementioned half-metals, C, N, P, O, S, and Se. That is, metallic elements are those elements that can become cations when forming halogen compounds and inorganic compounds.

[0045] Preferably, when the first element group is expressed as Mα, the second element group as Mβ, and the third element group as X, the composition formula is Mα. a Mβ b X c (OH) d This means that the valence of Mβ is set to n, satisfying: a + n × b = c + d, 2.7 < a < 3.3, 0 < b < 1, 0 < c < 6, and 0 < d < 6. Further preferred values ​​are: 2.7 < a < 3.3, 0.4 < b < 0.8, 2.0 < c < 2.8, and 1.5 < d < 3.3.

[0046] When the second element group consists only of elements with trivalent cations, and the solid electrolyte consists only of the first element group, the second element group, the third element group, and hydroxyl groups, the above composition formula Mα a Mβ b X c (OH) d In the given condition, the following conditions must be met: a + 3 × b = c + d, 2.7 < a < 3.3, 0 < b < 1, 0 < c < 6, and 0 < d < 6. Further preferred conditions are: 2.7 < a < 3.3, 0.4 < b < 0.8, 2.0 < c < 2.8, and 1.5 < d < 3.3.

[0047] In a preferred embodiment, the first element group consists only of Li. The second element group preferably includes elements that are trivalent cations. A preferred example of a trivalent cation is Al (aluminum) or Ga (gallium). In a preferred embodiment, the second element group consists only of at least one of Al and Ga. The third element group preferably includes F or Cl. More preferably, the third element group consists only of at least one of F and Cl.

[0048] Furthermore, it is preferable that the diffraction pattern of the solid electrolyte, obtained by X-ray diffraction using CuKα rays, has peaks in the ranges of 2θ being 21–24°, 32–34°, and 35.5–37.5°. More preferably, the second element group includes Al, and the diffraction pattern does not have peaks in the range of 2θ being 24–26°. This means that AlF3 is substantially absent.

[0049] When the second element group includes Al, the Raman spectrum of the solid electrolyte preferably shows a peak at 470 cm⁻¹. －1 Above and 570cm －1 Below and 720cm －1 Above and 820cm －1 The following peaks appear. Raman spectroscopy reveals a certain degree of structural homogeneity, which is considered one of the main reasons for the high ionic conductivity. Furthermore, the presence of 4-coordination in Al is considered another major reason for the high ionic conductivity; when Al is included in the second element group of the solid electrolyte, a coordination number of 4 is preferred for Al to be 60 mol% or more.

[0050] The aforementioned solid electrolyte is non-flammable and chemically stable, and does not produce hydrogen sulfide gas; therefore, it can provide an inherently safe all-solid-state secondary battery 1. Furthermore, the aforementioned solid electrolyte can be densified by compression molding rather than sintering, and does not react with the active materials during battery manufacturing.

[0051] A preferred example of a solid electrolyte includes lithium, aluminum, chlorine, fluorine, and hydroxyl groups. Another preferred example includes lithium, aluminum, fluorine, and hydroxyl groups. Yet another preferred example includes lithium, gallium, fluorine, and hydroxyl groups.

[0052] Figure 2 This is a diagram illustrating the manufacturing process of a solid electrolyte. In the manufacturing of the solid electrolyte, firstly, a compound of an alkali metal element and a halogen element is prepared (step S11). The alkali metal element group (i.e., one or more elements) is selected from the group consisting of Li, Na, and K. The halogen element group is selected from the group consisting of F, Cl, Br, and I. In one example of the compound, at least one of LiF and LiCl is prepared using step S11. It should be noted that step S11 can be omitted.

[0053] Next, a compound is prepared from a group of elements selected from metallic and half-metallic elements and a group of halogen elements (step S12). The group of elements selected from metallic and half-metallic elements is preferably composed of trivalent cations. This group of elements can be defined as a group of elements selected from metallic and half-metallic elements other than Li, Na, K, Zr, and Mg. The group of halogen elements is one or more elements selected from the group consisting of F, Cl, Br, and I. In one example of the compound, at least one of AlF3 and GaF3 is prepared using step S12.

[0054] Next, a hydroxide consisting of one or more alkali metal elements is prepared (step S13). The alkali metal element group is one or more elements selected from the group consisting of Li, Na, and K. In one example of the compound, LiOH is prepared using step S13. Steps S11 to S13 can be performed in any order.

[0055] Next, the materials prepared in steps S11 to S13 (or steps S12 to S13 if step S11 is not performed) are mixed, and the mixture is subjected to mechanochemical treatment (step S14). Mechanochemical treatment activates or reacts the particles in the mixture. Specifically, in step S14, the mixture is mechanically ground using a planetary mill. During mixing, only the materials prepared in steps S11 to S13 (or steps S12 to S13) may be mixed, or other materials may be added.

[0056] In mechanical grinding, for example, a planetary ball mill is used. In a planetary ball mill, the jar rotates on its own axis while the worktable carrying the jar revolves around it, thus generating very high impact energy. Mechanical grinding can also be performed using other types of pulverizers. Through the above mechanical grinding process, a powder (hereinafter also referred to as "processed powder") is obtained as the basis for the solid electrolyte used in the positive electrode layer 112, negative electrode layer 122, or solid electrolyte layer 13. In this example, the mechanical grinding process is performed at room temperature; however, conditions such as temperature can be appropriately changed.

[0057] The mechanochemically treated mixture (treated powder) is then heated at 40°C or higher for 30 minutes or more but less than 24 hours to obtain a solid electrolyte (step S15). At this point, the treated powder can be pressurized at 1 MPa or higher but less than 500 MPa.

[0058] Next, experimental examples of solid electrolytes will be described. The following experimental examples were conducted in a glove box or dry room with a dew point below -40°C.

[0059] (Experimental Example 1)

[0060] As raw materials, commercially available LiF (lithium fluoride) powder (High Purity Chemical Research Institute Co., Ltd., LIH20XB), commercially available LiCl powder (High Purity Chemical Research Institute Co., Ltd., LIH09XB), and commercially available AlF3 (aluminum fluoride) powder (High Purity Chemical Research Institute Co., Ltd., ALH17PB) were prepared. LiF, LiCl, and AlF3 were weighed at molar percentages of 25.0%, 50.0%, and 25.0%, respectively, and then pulverized and mixed using a mortar and pestle. Subsequently, mechanical grinding was performed using a planetary ball mill to obtain the processed powder.

[0061] In the mechanical grinding process, 100 ZrO2 balls (10mm in diameter) and 12g of mixed powder were placed into the ZrO2 (zirconia) jar (500cc) of a planetary ball mill, and mechanically ground at 400rpm for 20 hours to obtain the processed powder. Then, as... Figure 3 As shown, 200 mg of pre-treated powder is sandwiched between an upper punch 92 and a lower punch 93 made of SUS (stainless steel) inside a sleeve 91 made of PEEK resin. The solid electrolyte 2 is pressed and molded by applying pressure of 150 MPa and heating to 150°C for 1 hour.

[0062] <Determination of Ion Conductivity>

[0063] After the solid electrolyte 2 was returned to room temperature while being held between upper and lower punches 92 and 93, impedance measurements were performed using wires connected to the upper and lower punches 92 and 93, and the ionic conductivity was calculated. Impedance measurements were performed at a voltage of 10 mV and a frequency of 0.1 Hz to 1 MHz. The ionic conductivity was 1.6 × 10⁻⁶. －7 S / cm (1.6E-07 as recorded in Table 1. The same applies below).

[0064] <XRD Measurement>

[0065] A powder of solid electrolyte was obtained, and an X-ray diffraction pattern (hereinafter also referred to as "XRD pattern") was obtained from the powder using an X-ray diffraction (XRD) apparatus. A sealed tube X-ray diffraction apparatus (Bruker AXS Co., Ltd., D8-ADVANCE) was used. Measurements were performed using CuKα rays at 40 kV and 40 mA. The measurement step was 0.02°.

[0066] Figure 4 The upper part, indicated by mark 31, shows the XRD pattern of Experimental Example 1. The peaks appearing at marks 301 (29–31°, 34–36°, 49.5–50.5°) correspond to LiCl, the peak at marks 303 (24–26°) corresponds to AlF3, and the peak at marks 304 (20–23°) corresponds to Li3AlF6.

[0067] <Infrared Spectrophotometry>

[0068] For solid electrolytes, attenuated total reflection (ATR) was used to obtain infrared spectra. The measuring apparatus used was an FT-IR VERTEX 70V (manufactured by Bruker) as the light source, SiC as the detector, and DTGS (deuterated triglycine sulfate) as the detector. The resolution was 4 cm⁻¹. －1 The cumulative number of times was 256. As an auxiliary device, a Platinum ATR (1-time reflection ATR, incident angle 45°, using a diamond prism) was used.

[0069] Figure 5 The curves marked 411 and 412 represent the results of two measurements performed on the solid electrolyte of Experimental Example 1. The absorbance on the vertical axis represents the relative value in one measurement, and the results of the two measurements are shown staggered vertically.

[0070] (Experimental Example 2)

[0071] As with Example 1, commercially available LiF powder, LiCl powder, and AlF3 powder were prepared, along with commercially available LiOH (lithium hydroxide) powder (Sigma-Aldrich, 442410). LiF, LiCl, AlF3, and LiOH were weighed at molar percentages of 12.5, 25.0, 12.5, and 50.0, respectively, and pulverized and mixed using a mortar and pestle. Then, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Subsequently, the solid electrolyte was pressed into shape under the same conditions as in Example 1.

[0072] The ionic conductivity was measured to be 4.1 × 10⁻⁶, similar to that in Experimental Example 1. －4 S / cm. It should be noted that in Experiment 2, ionic conductivity was also measured during heating. It was observed that the ionic conductivity increased due to heating, and then, upon returning to room temperature, the ionic conductivity only decreased to approximately the value mentioned above.

[0073] Similar to Experiment 1, XRD measurements were performed. Figure 4 The XRD pattern of Experimental Example 2 is shown in the middle section indicated by label 32. The peaks appearing at positions 301 (29.5–30.5°, 34–35°, 49.5–50.5°) correspond to LiCl, and the peaks appearing at positions 302 (38–39°, 44–46°) correspond to LiF.

[0074] Infrared spectrophotometry was performed under the same conditions as in Experimental Example 1. Figure 5 The curves marked 421 and 422 represent the results of two measurements of the solid electrolyte in Experimental Example 2. Figure 5 The results of two measurements are shown staggered vertically. The presence of OH groups can be confirmed.

[0075] (Experimental Example 3)

[0076] In Experiment 3, commercially available AlF3 powder and commercially available LiOH powder were prepared as raw materials. AlF3 and LiOH were weighed at molar percentages of 20.0% and 80.0%, respectively, and then pulverized and mixed using a mortar and pestle. Subsequently, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1.

[0077] The ionic conductivity, measured in the same manner as in Experimental Example 1, was 1.0 × 10⁻⁶. －5 S / cm.

[0078] (Experimental Examples 4-8)

[0079] In Examples 4-8, commercially available LiF powder, LiCl powder, AlF3 powder, and LiOH powder were prepared as raw materials, similar to those in Example 2. In Example 4, LiF, LiCl, AlF3, and LiOH were weighed at molar percentages of 4.3, 8.7, 17.4, and 69.6, respectively, and pulverized and mixed using a mortar and pestle. Then, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Example 1. The ionic conductivity was measured to be 6.2 × 10⁻⁶, similar to that in Example 1. －4 S / cm.

[0080] In Experiment 5, LiF, LiCl, AlF3, and LiOH were weighed at molar percentages of 7.7%, 15.4%, 15.4%, and 61.5%, respectively, and then pulverized and mixed using a mortar and pestle. Following this, mechanical grinding was performed using a planetary ball mill to obtain a processed powder. Subsequently, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 1.0 × 10⁻⁶, as in Experiment 1. －3 S / cm.

[0081] Similar to Experiment 1, XRD measurements were performed. Figure 4 The lower part, indicated by mark 33, shows the XRD pattern of Experimental Example 3. The peaks appearing at the positions marked 302, at 38–39° and 44–46°, correspond to LiF.

[0082] In Experiment 6, LiF, LiCl, AlF3, and LiOH were weighed at molar percentages of 13.3, 20.0, 13.3, and 53.3 (sometimes the total value did not reach 100 due to rounding; the same applies below), and then pulverized and mixed using a mortar and pestle. Subsequently, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 2.1 × 10⁻⁶, as in Experiment 1. －4 S / cm.

[0083] In Experiment 7, LiF, LiCl, AlF3, and LiOH were weighed at molar percentages of 14.3, 14.3, 14.3, and 57.1, respectively, and then pulverized and mixed using a mortar and pestle. Following this, mechanical grinding was performed using a planetary ball mill to obtain a processed powder. Subsequently, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 5.0 × 10⁻⁶, as in Experiment 1. －4 S / cm.

[0084] In Experiment 8, LiF, LiCl, AlF3, and LiOH were weighed at molar percentages of 15.4%, 7.7%, 15.4%, and 61.5%, respectively, and then pulverized and mixed using a mortar and pestle. Following this, mechanical grinding was performed using a planetary ball mill to obtain a processed powder. Subsequently, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 1.2 × 10⁻⁶, as in Experiment 1. －4 S / cm.

[0085] (Experimental Example 9)

[0086] In Experiment 9, commercially available GaF3 (gallium fluoride (III)) (Alfa Aesar (catalog name), 32112) was used to replace AlF3 in Experiment 2. LiF, LiCl, GaF3, and LiOH were weighed at molar percentages of 12.5, 25.0, 12.5, and 50.0, respectively, and then pulverized and mixed using a mortar and pestle. Subsequently, mechanical grinding was performed using a planetary ball mill to obtain a processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 7.1 × 10⁻⁶, as in Experiment 1. －5 S / cm.

[0087] (Experimental Example 10)

[0088] In Experiment 10, commercially available ZrF4 (zirconium fluoride (IV)) (Strem Chemicals, 232-018-1) was used instead of AlF3 in Experiment 2. LiF, LiCl, ZrF4, and LiOH were weighed in molar percentages of 12.5, 25.0, 12.5, and 50.0, respectively, and pulverized and mixed using a mortar and pestle. Then, mechanical grinding was performed using a planetary ball mill to obtain a processed powder. Subsequently, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 4.2 × 10⁻⁶, as in Experiment 1. －7 S / cm.

[0089] (Experimental Example 11)

[0090] In Experiment 11, commercially available MgF2 (magnesium fluoride) (MGH18XB, High Purity Chemical Research Institute, Co., Ltd.) was used to replace AlF3 in Experiment 2. LiF, LiCl, MgF2, and LiOH were weighed at molar percentages of 12.5, 25.0, 12.5, and 50.0, respectively, and then pulverized and mixed using a mortar and pestle. Subsequently, mechanical grinding was performed using a planetary ball mill to obtain a processed powder. The solid electrolyte was then pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 1.0 × 10⁻⁶, as in Experiment 1. －9 S / cm.

[0091] (Experimental Example 12)

[0092] In Experiment 12, the same materials as in Experiment 2 were weighed according to the same molar percentage and pulverized and mixed using a mortar and pestle. Then, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterwards, similar to Experiment 1, as... Figure 3 As shown, the treated powder was sandwiched between the upper punch 92 and the lower punch 93 within the sleeve 91, and pressed at 150 MPa for 15 minutes at room temperature. Next, after releasing the pressure, it was heat-treated at 150°C for 1 hour. After cooling, impedance measurements were performed using wires connected to the upper and lower punches 92 and 93, similar to Example 1, to calculate the ionic conductivity. The ionic conductivity was 5.3 × 10⁻⁶. －5 S / cm.

[0093] (Experimental Example 13)

[0094] In Example 13, the same materials as in Example 5 were weighed according to the same molar percentage and pulverized and mixed using a mortar and pestle. Then, they were mechanically ground using a planetary ball mill to obtain a processed powder. Next, as in Example 12, the processed powder was pressed into shape without heating. After the pressure was released, it was heated at 150°C for 1 hour. After cooling, as in Example 1, impedance measurements were performed, and the ionic conductivity was calculated. The ionic conductivity was 1.3 × 10⁻⁶. －4 S / cm.

[0095] (Experimental Example 14)

[0096] In Experiment 14, commercially available LiCl powder, AlF3 powder, and LiOH powder were prepared as raw materials. LiCl, AlF3, and LiOH were weighed at molar percentages of 16.7%, 16.7%, and 66.7%, respectively, and then pulverized and mixed using a mortar and pestle. Subsequently, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 1.6 × 10⁻⁶, as in Experiment 1. －3 S / cm.

[0097] (Experimental Example 15)

[0098] In Experiment 15, in addition to the raw materials used in Experiment 14, commercially available GaF3 powder was prepared. LiCl, AlF3, GaF3, and LiOH were weighed in molar percentages of 16.7%, 13.3%, 3.3%, and 66.7%, respectively, and then pulverized and mixed using a mortar and pestle. Subsequently, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 1.4 × 10⁻⁶, as in Experiment 1. －3 S / cm.

[0099] (Experimental Example 16)

[0100] In Example 16, in addition to the raw materials used in Example 14, commercially available Al2O3 (alumina) powder (Sumitomo Chemical Co., Ltd., AKP-20) was prepared. LiCl, AlF3, Al2O3, and LiOH were weighed at molar percentages of 16.7, 15.0, 1.7, and 66.7, respectively, and pulverized and mixed using a mortar and pestle. Then, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Example 1. The ionic conductivity was measured to be 7.9 × 10⁻⁶, as in Example 1. －4 S / cm.

[0101] (Experimental Example 17)

[0102] In Example 17, in addition to the raw materials used in Example 14, commercially available B₂O₃ (boron oxide) powder (High Purity Chemical Research Institute Co., Ltd., BBO08PB) was prepared. LiCl, AlF₃, B₂O₃, and LiOH were weighed at molar percentages of 16.7, 15.0, 1.7, and 66.7, respectively, and pulverized and mixed using a mortar and pestle. Then, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Example 1. The ionic conductivity was measured to be 5.0 × 10⁻⁶, as in Example 1. －4 S / cm.

[0103] (Experimental Example 18)

[0104] In Experiment 18, in addition to the raw materials used in Experiment 1, commercially available ZrF4 powder was prepared. LiF, LiCl, AlF3, ZrF4, and LiOH were weighed in molar percentages of 7.7, 15.4, 13.8, 1.5, and 61.5, respectively, and then pulverized and mixed using a mortar and pestle. Subsequently, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 2.5 × 10⁻⁶, as in Experiment 1. －4 S / cm.

[0105] (Experimental Example 19)

[0106] In Experiment 19, in addition to the raw materials used in Experiment 1, commercially available MgF2 powder was prepared. LiF, LiCl, AlF3, MgF2, and LiOH were weighed in molar percentages of 1.6, 16.4, 14.8, 1.6, and 65.6, respectively, and pulverized and mixed using a mortar and pestle. Then, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 1.1 × 10⁻⁶, as in Experiment 1. －4 S / cm.

[0107] (Experimental Example 20)

[0108] In Experiment 20, in addition to the raw materials used in Experiment 1, commercially available Li₂SiF₆ (lithium hexafluorosilicate) powder (SynQuest Laboratories, M003-2-X2) was prepared. LiF, LiCl, AlF₃, Li₂SiF₆, and LiOH were weighed in molar percentages of 4.8, 15.9, 14.3, 1.6, and 63.5, respectively, and pulverized and mixed using a mortar and pestle. Then, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 1.8 × 10⁻⁶, as in Experiment 1. －4 S / cm.

[0109] (Experimental Example 21)

[0110] In Experiment 21, in addition to the raw materials used in Experiment 1, commercially available TiF4 (titanium fluoride (IV)) powder (Alfa Aesar, no part number) was prepared. LiF, LiCl, AlF3, TiF4, and LiOH were weighed in molar percentages of 7.7, 15.4, 13.8, 1.5, and 61.5, respectively, and pulverized and mixed using a mortar and pestle. Then, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 2.0 × 10⁻⁶, as in Experiment 1. －4 S / cm.

[0111] (Experimental Example 22)

[0112] In Experiment 22, in addition to the raw materials used in Experiment 14, commercially available ZnF2 (zinc fluoride) powder (High Purity Chemical Research Institute Co., Ltd., ZNH14XB) was prepared. LiCl, AlF3, ZnF2, and LiOH were weighed at molar percentages of 19.4%, 12.9%, 3.2%, and 64.5%, respectively, and then pulverized and mixed using a mortar and pestle. Subsequently, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 1.8 × 10⁻⁶, as in Experiment 1. －4 S / cm.

[0113] (Experimental Example 23)

[0114] In Experiment 23, in addition to the raw materials used in Experiment 14, commercially available LiBr (lithium bromide) powder (High Purity Chemical Research Institute Co., Ltd., LIH04XB) was prepared. LiCl, AlF3, LiBr, and LiOH were weighed at molar percentages of 12.5, 16.7, 4.2, and 66.7, respectively, and pulverized and mixed using a mortar and pestle. Then, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 5.3 × 10⁻⁶, as in Experiment 1. －4 S / cm.

[0115] (Experimental Example 24)

[0116] In Experiment 24, in addition to the raw materials used in Experiment 3, commercially available LiBr powder was prepared. AlF3, LiBr, and LiOH were weighed at molar percentages of 16.7%, 16.7%, and 66.7%, respectively, and then pulverized and mixed using a mortar and pestle. Subsequently, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 4.4 × 10⁻⁶, as in Experiment 1. －4 S / cm.

[0117] (Experimental Example 25)

[0118] In Experiment 25, commercially available NaCl (sodium chloride) powder (Sigma-Aldrich, 793566), commercially available AlF3 powder, and commercially available NaOH (sodium hydroxide) powder (Sigma-Aldrich, 757527) were prepared. NaCl, AlF3, and NaOH were weighed at molar percentages of 16.7%, 16.7%, and 66.7%, respectively, and then pulverized and mixed using a mortar and pestle. Subsequently, mechanical grinding was performed using a planetary ball mill to obtain the processed powder. Afterward, the solid electrolyte was pressed into shape under the same conditions as in Experiment 1. The ionic conductivity was measured to be 7.0 × 10⁻⁶, as in Experiment 1. －5 S / cm.

[0119] The mixing ratios and ionic conductivity of the materials in the above experimental examples are shown in Table 1. In Table 1, the experimental examples with higher ionic conductivity are marked with "*".

[0120] Table 1

[0121]

[0122] As shown in Table 1, in Experiments 2 to 9 and 12 to 25, the result was 1.0 × 10⁻⁶ at room temperature. －5High ionic conductivity above S / cm.

[0123] Comparing Experiment 1 with Experiments 2, 4 to 8, it was determined that the addition of LiOH to the material resulted in a significant increase in ionic conductivity. Furthermore, infrared spectrophotometry in Experiment 2 confirmed that the presence of OH groups contributed to this increase.

[0124] In Experiments 2 and 5, although the materials contained metal fluorides (AlF3), Figure 4 In the XRD patterns (curves marked 32 and 33), there are no peaks originating from AlF3 (the peak near 2θ = 25° in mark 303). Furthermore, peaks originating from other Al-containing compounds (Li3AlF6, etc.) are also absent. On the other hand, unspecified low-intensity peaks are observed in the 2θ ranges of 21–24°, 32–34°, and 35.5–37.5° in mark 305. In other words, the aforementioned solid electrolyte exhibits the following characteristic: in the diffraction pattern obtained by X-ray diffraction using CuKα rays, peaks are present in the ranges of 2θ = 21–24°, 32–34°, and 35.5–37.5°.

[0125] Although the exact mechanism is unclear, it is believed that the high ionic conductivity is due to Li, Al, OH (hydroxyl groups), and halogens. Additionally, [the text abruptly ends here]. Figure 4 Comparing the curve of Experimental Example 1 marked with 31 with the curves of Experimental Examples 2 and 5 marked with 32 and 33, no peak of AlF3 was observed in curves 32 and 33. Therefore, it was determined that the diffraction pattern obtained by X-ray diffraction using CuKα rays preferably does not have a peak in the range of 2θ being 24 to 26°.

[0126] Furthermore, in the curve of Experimental Example 2 marked with 32, there is a peak of LiCl marked with 301. However, in the curve of Experimental Example 5 marked with 33, there is no peak of LiCl. Experimental Example 5 obtained high ionic conductivity, thus it is determined that it is more preferable that there is no peak of LiCl.

[0127] It should be noted that relatively high ionic conductivity was also obtained in Experiment 3, thus indicating that lithium halide is not necessary as a material.

[0128] When the composition of a solid electrolyte is expressed as Li a Al b X c (OH) dWhen (where X is at least one of F and Cl), a + 3 × b = c + d, 2.7 < a < 3.3, 0 < b < 1, 0 < c < 6, 0 < d < 6. If a is fixed at 3, then in experimental examples 2 to 8, b is 0.43 to 0.75, c is 2.25 to 2.57, and d is 1.71 to 3. Regarding a to d, if the above range has a width of about 10%, the preferred values ​​are: 2.7 < a < 3.3, 0.4 < b < 0.8, 2.0 < c < 2.8, 1.5 < d < 3.3.

[0129] On the other hand, it is hypothesized that Li can be replaced by other alkali metal elements, and that Al can be replaced by other metallic and / or half-metallic elements (in Experimental Example 9, even when Al was replaced by Ga, high ionic conductivity was obtained). It is also hypothesized that F and Cl can be replaced by other halogen elements. Therefore, when the first element group, consisting of one or more alkali metal elements selected from the group consisting of Li, Na, and K, is designated as Mα, the second element group, consisting of one or more metallic and half-metallic elements selected from the group consisting of Li, Na, and K, is designated as Mβ, and the third element group, consisting of one or more halogen elements selected from the group consisting of F, Cl, Br, and I, is designated as X, the composition formula of the solid electrolyte can be expressed as Mα. a Mβ b X c (OH) d a, b, c, and d satisfy the above conditions.

[0130] As shown in Experimental Examples 10 and 11, when Mβ is set to Zr or Mg, it is determined that high ionic conductivity cannot be obtained. Therefore, it is preferable to exclude these metal elements from Mβ.

[0131] Furthermore, regarding Experimental Examples 12 and 13, the treated powders, similar to those in Experimental Examples 2 and 5, were molded and then heated without pressure. This demonstrated that pressure during heating is not a necessary condition for improving ionic conductivity. The preferred pressure range also depends on the degree of mechanochemical treatment; therefore, it can be appropriately applied within a range of 1 MPa to 500 MPa.

[0132] Furthermore, the heating temperature for the treated powder depends on the degree of mechanochemical treatment; therefore, high temperatures are not required. Heating can be performed at 40°C or above for at least 30 minutes. It has been confirmed that high ionic conductivity is obtained even at low temperatures. There is no upper limit to the heating temperature; for example, a heating temperature below 300°C is acceptable. Similarly, there is no upper limit to the heating time; for example, a heating time below 24 hours is acceptable.

[0133] In Experiments 15 to 17 and 22, other materials (GaF3, Al2O3, B2O3, or ZnF2) were added to LiCl, AlF3, and LiOH, which were used as raw materials in Experiment 14. Specifically, Ga was added to Experiment 15, B to Experiment 17, and Zn to Experiment 22. In Experiments 18 to 21, other materials (ZnF4, MgF3, Li2SiF6, or TiF4) were added to LiF, LiCl, AlF3, and LiOH, which were used as raw materials in Experiments 2 and 4 to 8. Specifically, Zr was added to Experiment 18, Mg to Experiment 19, Si to Experiment 20, and Ti to Experiment 21.

[0134] As shown in Experimental Examples 15-22, the second element group only needs to contain one or more trivalent cations selected from metallic and half-metallic elements; other metallic and half-metallic elements may also be present. Furthermore, the preferred element in the second element group is at least one of Al and Ga.

[0135] In the solid electrolyte of Experimental Example 23, the halogen elements included Cl, F, and Br; in the solid electrolyte of Experimental Example 24, F and Br were included. Based on these examples, it is inferred that the third element group is preferably selected from one or more halogen elements chosen from the group consisting of F, Cl, and Br, and more preferably from one or more halogen elements chosen from the group consisting of F, Cl, Br, and I.

[0136] As shown in Experimental Examples 14-24, solid electrolytes containing Li, Al, F, and OH, or solid electrolytes containing Li, Al, F, Cl, and OH, may contain Ga, Al oxides, B, Zr, Mg, Si, Ti, Zn, and Br. It should be noted that, as shown in Experimental Examples 10 and 11, it is not preferable to contain large amounts of Zr or Mg. Generally, among the metal elements and half-metal elements other than alkali metal elements (Group 1), the elements contained in Group 2 are preferably 50 mol% or more. According to Experimental Examples 18-22, among the metal elements and half-metal elements other than alkali metal elements, the elements contained in Group 2 are preferably 80 mol% or more, and more preferably 90 mol% or more. In this case, Al is also the preferred Group 2 element.

[0137] In the solid electrolyte of Experimental Example 25, Na was used instead of Li in Experimental Example 14. Therefore, it is speculated that the first element group is preferably one or more alkali metal elements selected from the group consisting of Li and Na, and preferably one or more alkali metal elements selected from the group consisting of Li, Na and K.

[0138] Similarly, in Experiments 14 to 24, the composition of the solid electrolyte is expressed as Lia Al b X c (OH) d When (where X is at least one of F and Cl), a + 3 × b = c + d, 2.7 < a < 3.3, 0 < b < 1, 0 < c < 6, 0 < d < 6. Furthermore, in experimental examples 14 to 24, the following preferred ranges are also satisfied: referring to experimental examples 2 to 8, 2.7 < a < 3.3, 0.4 < b < 0.8, 2.0 < c < 2.8, 1.5 < d < 3.3.

[0139] <Evaluation of Potential Window>

[0140] Next, the evaluation of the potential window for Experimental Example 2 will be explained. The treated powder of Experimental Example 2 was subjected to... Figure 3 The same resin sleeve 91 is clamped within upper and lower SUS (stainless steel) punches 92 and 93, pressurized to 150 MPa, and heated to 150°C for molding. Afterwards, the punches on one side are removed, as... Figure 6 As shown, a Li metal foil 94 with a diameter of 8 mm and a thickness of 0.2 mm was placed under a solid electrolyte 2. Cyclic voltammetry was performed using wiring connected to upper and lower punches 92 and 93. The measurement conditions were set as follows: voltage range of +4.1 V to -0.5 V, and scan rate of 10 mV / sec.

[0141] Figure 7 The results obtained using cyclic voltammetry are shown. The horizontal axis represents the potential (-0.5 to 4.0 V for Li / Li). ＋ The vertical axis represents the current density (-0.3 to 0.3 mA / cm²). 2 A redox current was observed near 0V accompanying the precipitation and dissolution of Li, suggesting the presence of Li ion conduction. Furthermore, no significant redox current other than that observed during Li precipitation and dissolution was observed over a wide voltage range of 0–4V, indicating high redox resistance (i.e., a wide potential window).

[0142] <Determination of Raman Spectroscopy>

[0143] Next, the results of the Raman spectroscopy measurements performed on Experiment 14 will be explained. Figure 8This is a graph showing the Raman spectrum obtained using the measurement. The measurement was performed using an HR Evoluiton (Horiba Jobin Yvon) with the following conditions: measurement mode: micro Raman, beam diameter: 2 μm, light source: 532 nm (YAG laser, 2nd Harmonic), laser power: 25 mW, diffraction grating: Single 1800 gr / mm, slit: 100 μm, cross slit: 100 μm, detector (CCD (Symphony II)).

[0144] Regarding the solid electrolyte, no significant peaks were observed in the XRD, indicating that although it is a near-amorphous material, it exhibits a certain degree of structural homogeneity in the Raman spectrum. This structural homogeneity is considered one of the main reasons for its high ionic conductivity. Based on the conditions of Experimental Example 14, it can be said that when the first element group includes Li and the second element group includes Al, the Raman spectrum at 470 cm⁻¹... －1 Above and 570cm －1 Below and 720cm －1 Above and 820cm －1 The following peak appears.

[0145] <NMR Spectroscopy Measurement>

[0146] Next, the solid samples from Experimental Example 14 were tested. 27 The results of Al NMR (nuclear magnetic resonance) spectroscopy measurements are explained. Figure 9 This is a graph showing the NMR spectrum obtained using the measurement. The measurement was performed using an "ECA 600" (manufactured by JOEL RESONANCE) with the following atmosphere: dry nitrogen; temperature: room temperature (~22°C); chemical shift standard: aluminum nitrate aqueous solution (external standard: 0 ppm); and observation frequency. 27 The pulse width was 156.38565 MHz, the pulse width was 806 kHz, the pulse angle was 30°, the pulse length was 1 μs, the pulse repetition time was ACQTM = 10.158 ms, the pulse PD was 16 s, the data points were POINT = 16384, the pulse mode was DD / MAS method, and the sample rotation speed was 25 kHz.

[0147] The coordination number (chemical bond state) of Al was determined by solid-state NMR spectroscopy. In Experimental Example 14, the coordination number of 94 mol% (i.e., 90 mol% or more) of Al was 4. Therefore, it is considered that the presence of a large amount of Al with 4 coordination groups is one of the main reasons for the high ionic conductivity, and it is preferable that the coordination number of 60 mol% or more of Al is 4.

[0148] <Fabrication of an all-solid-state battery (1)>

[0149] Prepare the pre-treated powder of Experiment Example 2, Li(Ni,CO,Mn)O2 powder as the positive electrode active material, and carbon powder as the conductive additive. Weigh and mix the pre-treated powder, positive electrode active material powder, and conductive additive powder in a weight ratio of 50:50:1 to obtain the positive electrode blended powder.

[0150] In the settings Figure 3 200 mg of the treated powder from Example 2 was placed in a PEEK resin sleeve 91 with an inner diameter of 10 mm, and uniaxially pressed at 150 MPa using upper and lower punches 92 and 93. One punch was removed, and 30 mg of the above-mentioned positive electrode blending powder was weighed and placed on the pressed treated powder. Uniaxial pressing was then performed at 150 MPa and 150 °C using upper and lower punches 92 and 93. After returning to room temperature, the punch on the opposite side to the positive electrode was removed, and an 8 mm diameter, 0.2 mm thick Li metal foil was placed on top of the solid electrolyte, allowing the punch to return to its original position.

[0151] <Evaluation of all-solid-state batteries (1)>

[0152] A charge-discharge test of a solid-state battery was conducted at room temperature using wires connected to the upper and lower punches of a pair of metals.

[0153] First, set the charging termination voltage to 4.0V and the CC charging current to 150μA / cm. 2 Set the CV charging current to 30μA / cm 2 The all-solid-state battery is charged at 150 μA / cm. 2 The device is charged with a constant current (CC) until it reaches a voltage of 4.0V, and then charged with a constant voltage (CV) until the current reaches 30μA / cm. 2 .

[0154] Next, for the charged all-solid-state battery, the discharge termination voltage was set to 2.1V and the CC discharge current was set to 150μA / cm. 2 The CV discharge current is set to 30 μA / cm. 2 Discharge operation is performed. That is, at 150 μA / cm. 2 Discharge at a constant current (CC) until a voltage of 2.1V is reached, followed by discharge at a constant voltage (CV) until a current value of 30μA / cm is reached. 2 .

[0155] Figure 10The obtained discharge curves are shown. The horizontal axis represents capacity (0–1.4 mAh), and the vertical axis represents single-cell potential (1.5–4.0 V). The discharge capacity is 1.3 mAh. This experiment demonstrates that solid electrolytes can be used in the solid electrolyte layer and positive electrode layer of all-solid-state batteries.

[0156] <Fabrication of All-Solid-State Battery (2)>

[0157] Prepare the pre-treated powder for Experiment Example 2, LiFePO4 powder as the positive electrode active material, and Li4Ti5O as the negative electrode active material. 12 The powder, and carbon powder as a conductive additive. The treated powder, positive electrode active material powder, and conductive additive powder are weighed and mixed in a weight ratio of 50:50:1 to obtain a positive electrode blended powder. Separately, the treated powder, negative electrode active material powder, and conductive additive powder are weighed and mixed in a weight ratio of 50:50:1 to obtain a negative electrode blended powder.

[0158] In the settings Figure 3 200 mg of the treated powder from Example 2 was placed in a PEEK resin sleeve 91 with the same 10 mm inner diameter hole, and uniaxially pressed at 150 MPa using upper and lower punches 92 and 93. After removing one side of the punch, 30 mg of the above-mentioned positive electrode blending powder was weighed and placed on the pressed treated powder, and uniaxially pressed again at 150 MPa.

[0159] Remove the punch from the side opposite to the positive electrode, weigh 30 mg of the above-mentioned negative electrode blending powder, place it on the pressed and treated powder, and uniaxially press it at 150 MPa and 150 °C using upper and lower punches 92 and 93. Afterward, return it to room temperature.

[0160] <Evaluation of all-solid-state batteries (2)>

[0161] A charge-discharge test of a solid-state battery was conducted at room temperature using wires connected to the upper and lower punches of a pair of metals.

[0162] First, set the charging termination voltage to 2.2V and the CC charging current to 150μA / cm. 2 Set the CV charging current to 30μA / cm 2 The all-solid-state battery is charged at 150 μA / cm. 2 The device is charged with a constant current (CC) until it reaches a voltage of 2.2V, and then charged with a constant voltage (CV) until the current reaches 30μA / cm. 2 .

[0163] Next, for the charged all-solid-state battery, the discharge termination voltage was set to 1.0V and the CC discharge current was set to 150μA / cm.2 Set the CV discharge current to 30 μA / cm 2 Discharge operation is performed. That is, at 150 μA / cm. 2 Discharge at a constant current (CC) until a voltage of 1.0V is reached, followed by discharge at a constant voltage (CV) until a current value of 30μA / cm is reached. 2 .

[0164] Figure 11 The obtained discharge curves are shown. The horizontal axis represents capacity (0–1.2 mAh), and the vertical axis represents single-cell potential (0.0–2.5 V). The discharge capacity is 1.0 mAh. This experiment demonstrates that solid electrolytes can be used in the solid electrolyte layer, positive electrode layer, and negative electrode layer of all-solid-state batteries.

[0165] Various modifications can be made to the aforementioned solid electrolyte, its manufacturing method, and the battery.

[0166] Solid electrolytes may contain impurities, as described above with the formula Mα. a Mβ b X c (OH) d The substance indicated is included as the main component. The main component refers to the component with the largest mass percentage among the components contained in the solid electrolyte. The mass percentage of the main component in the solid electrolyte is preferably 80% by mass or more, more preferably 90% by mass or more. The solid electrolyte can be mixed with other substances to be used as an electrolyte material. The mass percentage of the aforementioned solid electrolyte in the electrolyte material is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0167] Figure 1 The solid electrolyte layer 13 may contain substances other than the solid electrolyte described above. The solid electrolyte used in the all-solid-state secondary battery 1 does not necessarily need to be included in all of the positive electrode 11, negative electrode 12, and solid electrolyte layer 13; it is sufficient that it is included in at least one of these three. The solid electrolyte can be used in batteries other than all-solid-state secondary batteries, and also for purposes other than batteries. In the manufacture of the solid electrolyte described above, mechanochemical treatments other than mechanical grinding can be performed.

[0168] The components in the above-described embodiments and their variations can be appropriately combined as long as they do not contradict each other.

[0169] Although the invention has been described in detail, the description is illustrative and not limiting. Therefore, it can be said that numerous modifications and solutions can be adopted without departing from the scope of the invention.

[0170] Explanation of reference numerals in the attached figures

[0171] 1. All-solid-state secondary battery

[0172] 2. Solid electrolytes

[0173] 11 Positive electrode

[0174] 12 Negative electrode

[0175] 13 Solid electrolyte layer

[0176] Steps S11 to S14

Claims

1. A solid electrolyte comprising: The first element group consists of one or more alkali metal elements selected from the group consisting of Li, Na and K. The second element group consists of one or more trivalent cations selected from metallic elements and half-metallic elements; The third element group, which consists of one or more halogens selected from the group consisting of F, Cl, Br, and I; and Hydroxyl group.

2. The solid electrolyte according to claim 1, wherein, The second element group includes Al or Ga.

3. The solid electrolyte according to claim 1, wherein, Of the metallic elements and half-metallic elements other than alkali metals, the elements contained in the second element group account for more than 50 mol%.

4. The solid electrolyte according to claim 2, wherein, The second element group includes Al.

5. The solid electrolyte according to claim 1, wherein, The third element group includes F or Cl.

6. The solid electrolyte according to claim 1, wherein, When the first element group is expressed as Mα, the second element group as Mβ, and the third element group as X, the composition formula is Mα. a Mβ b X c (OH) d It means that, and satisfies: a + 3 × b = c + d 2.7＜a＜3.3、 0＜b＜1、 0 < c < 6, and 0＜d＜6。 7. The solid electrolyte according to claim 1, wherein, In the diffraction pattern obtained by X-ray diffraction using CuKα rays, peaks exist in the ranges of 2θ: 21–24°, 32–34°, and 35.5–37.5°.

8. The solid electrolyte according to claim 4, wherein, In the diffraction pattern obtained by X-ray diffraction using CuKα rays, there are no peaks in the range of 2θ 24–26°.

9. The solid electrolyte according to claim 4, wherein, The first element group includes Li, which, in the Raman spectrum, is at 470 cm⁻¹ －1 Above and 570cm －1 Below and 720cm －1 Above and 820cm －1 The following peak appears.

10. The solid electrolyte according to claim 4, wherein, In Al, the coordination number is 4 for 60 mol% or more.

11. A battery comprising: positive electrode; Negative electrode; and A solid electrolyte layer is disposed between the positive electrode and the negative electrode. The solid electrolyte according to any one of claims 1 to 10 is contained in at least one of the positive electrode, the negative electrode, and the solid electrolyte layer.

12. A method for manufacturing a solid electrolyte, comprising the following steps: a) Prepare a first material, wherein the first material is a compound consisting of an element group consisting of one or more elements that are trivalent cations selected from metallic elements and half-metallic elements, and an element group consisting of one or more halogen elements selected from the group consisting of F, Cl, Br and I. b) Prepare a second material, which is a hydroxide of an element group consisting of one or more alkali metal elements selected from the group consisting of Li, Na and K; c) subjecting a mixture comprising the first material and the second material to mechanochemical treatment; and d) The mixture that has undergone mechanochemical treatment is heated at or above 40°C for more than 30 minutes and less than 24 hours to obtain a solid electrolyte.

13. The method for manufacturing a solid electrolyte according to claim 12, wherein, Prior to step c), the following steps are also included: e) Prepare a third material, said third material being a compound consisting of an element group consisting of one or more alkali metal elements selected from the group consisting of Li, Na, and K, and an element group consisting of one or more halogen elements selected from the group consisting of F, Cl, Br, and I. In step c), the mixture comprising the first material, the second material and the third material is subjected to mechanochemical treatment.

14. The method for manufacturing a solid electrolyte according to claim 12 or 13, wherein, In step d), the mixture that has undergone mechanochemical treatment is pressurized at a pressure of 1 MPa or more and 500 MPa or less.

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