Ion conductive substance, solid electrolyte, and battery

Abstract

The present disclosure provides an ion conductive substance which contains: a metal element M, which is at least one among an alkali metal element, a tetravalent metal element, and a pentavalent metal element; a halogen element; a divalent metal element D; and an oxygen element. The ion conductive substance has a diffraction peak having a full width at half maximum of 2.0-10° in the 2θ angle range of 5-20° in an X-ray diffraction chart obtained through measurement using CuKα rays at 25 °C, and contains the divalent metal element D in an amount of 2.5-18 mol%.

Description

Ion-conducting materials, solid electrolytes, batteries

[0001] The present disclosure relates to ion-conducting materials, solid electrolytes, and batteries.

[0002] In recent years, solid electrolytes have been attracting attention as electrolytes for use in electrochemical devices such as lithium-ion batteries (Patent Documents 1 to 4). Compared with conventional electrolytic solutions, solid electrolytes have superior high-temperature durability, high-voltage resistance, and the like, and are therefore considered useful for improving battery performance such as safety, high capacity, rapid charge / discharge, and pack energy density.

[0003] As described in Patent Documents 1 to 4, a halide solid electrolyte containing lithium and metal elements other than lithium (lithium-based halide solid electrolyte) is known as a material used for the solid electrolyte of a lithium ion battery. Halide solid electrolytes are highly flexible and do not require sintering, and they are free from harmful hydrogen sulfide (H ２ They have advantages not found in oxide- or sulfide-based solid electrolytes, such as high safety because they do not release sulfur dioxide (S). In addition to lithium-ion batteries, research is also underway on halide-based solid electrolytes that use other alkali ions, such as sodium and potassium, which are more abundant than lithium.

[0004] International Publication No. 2020 / 070957 International Publication No. 2021 / 024876 International Publication No. 2021 / 024785 International Publication No. 2021 / 024783

[0005] Here, hydrogen sulfide is known to be a highly hazardous gas to the human body, with an inhalation LC50 of 9.23 ppm / 4 h in rats, for example. Therefore, concerns have long been raised about the adverse effects of sulfide-based solid electrolytes on the human body. While halide solid electrolytes have traditionally been recognized as posing little risk, the inventors' extensive research has revealed that halide solid electrolytes react with moisture to release corrosive gases such as hydrogen halide. Therefore, if a halide solid electrolyte inside a battery reacts with moisture for some reason, corrosive gases are released, which can accelerate the deterioration of the casing and other components.

[0006] The present disclosure has been made in view of the above circumstances, and aims to provide an ion-conductive material that suppresses the generation of harmful gases, and a solid electrolyte and a battery that include the ion-conductive material.

[0007] The present disclosure includes the following exemplary embodiments. [1] An ion-conductive material containing a metal element M which is at least one of an alkali metal element, a tetravalent metal element, and a pentavalent metal element, a halogen element, a divalent metal element D, and an oxygen element, wherein an X-ray diffraction chart obtained by measurement at 25°C using CuKα radiation has a diffraction peak with a half-width of 2.0 to 10° in a 2θ angle range of 5 to 20°, and the content of the divalent metal element D is 2.5 to 18 mol %. [2] The ion-conductive material of [1], wherein the divalent metal element D is at least one element selected from the group consisting of Mg, Ca, Sr, and Ba. [3] The ion-conductive material of [1] or [2], wherein the halogen element is chlorine. [4] The ion-conductive material according to any one of [1] to [3], having a Li content of 15 to 35 mol%, an M content of 1 to 15 mol%, a halogen content of 30 to 60 mol%, and a divalent metal element D content of 2.5 to 18 mol%. [5] A solid electrolyte comprising the ion-conductive material according to any one of [1] to [4]. [6] A battery comprising the solid electrolyte according to [5].

[0008] According to the present disclosure, it is possible to provide an ion-conductive material that suppresses the generation of harmful gases, and also to provide a solid electrolyte and a battery that include the ion-conductive material.

[0009] Fig. 1 shows X-ray diffraction charts of the ion-conductive materials of Examples 1 to 7 and Comparative Examples 1 and 2. Fig. 2 shows Arrhenius plots obtained for the ion-conductive materials of Examples 1 to 4.

[0010] The ion-conductive material of this embodiment contains a metal element M, which is at least one of an alkali metal element, a tetravalent metal element, and a pentavalent metal element, a halogen element, a divalent metal element D, and an oxygen element. In an X-ray diffraction chart obtained by measurement using CuKα radiation at 25°C, the material has a diffraction peak with a half-width of 2.0 to 10° in a 2θ angle range of 5 to 20°, and the content of the divalent metal element D is 2.5 to 18 mol%. The ion-conductive material of this embodiment may have a crystal structure constituted by the alkali metal element, the metal element M, the halogen element, the divalent metal element D, and the oxygen element. The ion-conductive material of this embodiment may be a single compound.

[0011] In an X-ray diffraction chart obtained by measurement using CuKα radiation at 25°C, a diffraction peak with a 2θ angle in the range of 5 to 20° corresponds to the crystallinity of the ion-conductive material and serves as an index for evaluating crystallinity. When the half-width of the diffraction peak is equal to or less than the upper limit, the crystallinity is high, and the structure of the ion-conductive material is stabilized, making it easier to suppress the generation of harmful gases (e.g., corrosive gases). On the other hand, when the half-width of the diffraction peak is equal to or greater than the lower limit, the decrease in alkali metal ion conductivity due to further increased crystallinity can be suppressed, and the alkali metal ions (e.g., lithium ions) in the structure become more mobile as the material approaches amorphous. As a result, the generation of harmful gases can be suppressed while suppressing the decrease in ionic conductivity.

[0012] The half width of the diffraction peak may be, for example, 2.0 to 9.0°, 2.1 to 7.5°, or 2.2 to 7.0°. In this specification, the half width is the full width at half maximum (FWHM) unless otherwise specified.

[0013] The alkali metal element contained in the ion-conductive material of this embodiment may be any of Li, Na, K, Rb, and Cs, but may also include at least one of Li, Na, and K, may include at least one of Li and Na, may include Li, or may be Li.

[0014] In the ion-conductive material of this embodiment, the alkali metal element may be one type or two or more types. When the alkali metal element contains two or more types of alkali metal elements, the proportion of one type of alkali metal element among the alkali metal elements contained in the ion-conductive material may be, for example, 80 mol% or more, 90 mol% or more, or 95 mol% or more. The one type of alkali metal element (i.e., the alkali metal element contained in the ion-conductive material with the highest molar content) may be any one of Li, Na, and K, or may be either Li or Na, or may be Li.

[0015] The content of the alkali metal element in the ion-conductive material may be, for example, 10 to 40 mol %, 15 to 35 mol %, or 17 to 33 mol % relative to the total amount of atoms contained in the ion-conductive material.

[0016] The metal element M is at least one of a tetravalent metal element and a pentavalent metal element. The ion-conductive material may contain one or both of one or more tetravalent metal elements and one or more pentavalent metal elements.

[0017] The tetravalent metal element may include at least one metal element selected from the group consisting of Ti, Zr, and Hf, and may include Zr. The pentavalent metal element may include at least one of Nb and Ta, and may include Ta. The metal element M may include at least one metal element selected from the group consisting of Ti, Zr, Hf, Nb, and Ta, and may include at least one of Zr and Ta.

[0018] The content of the metal element M in the ion-conductive material may be, for example, 0.5 to 20 mol %, 1 to 15 mol %, or 1.5 to 12 mol % relative to the total amount of atoms contained in the ion-conductive material.

[0019] When the ion-conductive material contains Zr, the content of Zr may be, for example, 70 mol% or more, 80 mol% or more, 85 mol% or more, or 90 mol% or more, relative to the total amount of metal element M. When the ion-conductive material contains Zr, the content of Zr may be, for example, 99.9 mol% or less, 99 mol% or less, 98 mol% or less, 97 mol% or less, or 95 mol% or less, relative to the total amount of metal element M. When the ion-conductive material contains Zr, the content of Zr may be adjusted within the above-mentioned range, and may be, for example, 70 to 99.9 mol% or 80 to 99 mol% relative to the total amount of metal element M.

[0020] When the ion-conductive substance contains Ta, the content of Ta may be, for example, 70 mol% or more, 80 mol% or more, 85 mol% or more, or 90 mol% or more, relative to the total amount of metal elements M. When the ion-conductive substance contains Ta, the content of Ta may be, for example, 99.9 mol% or less, 99 mol% or less, 98 mol% or less, 97 mol% or less, or 95 mol% or less, relative to the total amount of metal elements M. When the ion-conductive substance contains Ta, the content of Ta may be adjusted within the above-mentioned range, and may be, for example, 70 to 99.9 mol% or 80 to 90 mol% relative to the total amount of metal elements M.

[0021] The halogen element contained in the ion-conductive material of this embodiment may be any one of F, Cl, Br, and I, or may contain at least one of Cl, Br, and I, or may contain at least one of Cl and Br, or may contain Cl. The ion-conductive material may contain only one halogen element, or may contain two or more halogen elements.

[0022] The content of halogen elements in the ion-conductive material may be, for example, 25 to 65 mol%, 30 to 60 mol%, 32 to 55 mol%, or 35 to 50 mol% relative to the total amount of atoms contained in the ion-conductive material. The content of chlorine in the ion-conductive material may be, for example, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, or 95 mol% or more relative to the total amount of halogen elements.

[0023] The ionically conductive material contains a divalent metal element D. The divalent metal element D has a high affinity for halogen elements such as Cl, and suppresses the detachment of halogen elements when the ionically conductive material comes into contact with moisture, or suppresses the generation of hydrogen halide by binding the generated halogen elements.

[0024] Examples of the divalent metal element D include alkaline earth metals and Zn. The ion-conductive material may contain one or more divalent metal elements D. When the divalent metal element D is an alkaline earth metal, it is preferable to include an element belonging to a higher period among alkaline earth metals, from the viewpoint of further suppressing the generation of hydrogen halide. The divalent metal element D may include at least one element selected from Mg, Ca, Sr, and Ba, or may include at least one element selected from Mg, Sr, and Ba, or may include Mg, and more preferably includes at least one of Sr and Ba.

[0025] The generation of hydrogen halide can be further suppressed by including a predetermined amount or more of the divalent metal element D in the ion-conductive material. The content of the divalent metal element D in the ion-conductive material may be, for example, 2.8 to 16 mol%, 3 to 15 mol%, 5 to 15 mol%, 6 to 15 mol%, 6.5 to 15 mol%, or 7 to 14.5 mol% relative to the total amount of atoms included in the ion-conductive material.

[0026] The content of oxygen element in the ion conductive material may be, for example, 3 to 30 mol%, 5 to 25 mol%, 8 to 22 mol%, 10 to 20 mol%, or 12 to 20 mol% relative to the total amount of atoms contained in the ion conductive material.

[0027] The ion-conductive material of this embodiment may further contain a dopant element X. The dopant element X is a tetrahedral structure XO with four oxygen atoms. ４ Specifically, the dopant element X may include at least one of P and S. The dopant element X may include S.

[0028] The content of the dopant element X in the ion-conductive material may be, for example, 0.05 to 5 mol %, 0.1 to 3 mol %, 0.2 to 2 mol %, or 0.3 to 1.5 mol % relative to the total amount of atoms contained in the ion-conductive material.

[0029] The content of the dopant element X in the ion-conductive material may be, for example, 50 mol % or less, 1 to 40 mol %, 5 to 35 mol %, or 10 to 30 mol % of the content of the metal element M. The content of the dopant element X in the ion-conductive material may be, for example, 40 mol % or less, 30 mol % or less, or 25 mol % or less of the content of the metal element M.

[0030] The ion-conductive material may further contain a metal element M2 that is a metal element other than a divalent, tetravalent, or pentavalent element. Examples of the metal element M2 include monovalent metal elements (excluding alkali metal elements), trivalent metal elements, and metal elements with a valence of hexavalent or higher.

[0031] Examples of monovalent metal elements include Ag, etc. Examples of trivalent metal elements include Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Al, Ga, In, Sb, and Bi, etc.

[0032] The content of M2 may be, for example, 30 mol% or less, 20 mol% or less, 15 mol% or less, or 10 mol% or less, relative to the total amount of metal element M and metal element M2 contained in the ion conductive material. The content of M2 may be, for example, 0.1 mol% or more, 1 mol% or more, 2 mol% or more, 2.5 mol% or more, 3 mol% or more, or 5 mol% or more, relative to the total amount of metal element M and metal element M2 contained in the ion conductive material. The content of M2 may be adjusted within the above-mentioned range and may be, for example, 0.1 to 30 mol% or 1 to 20 mol% relative to the total amount of metal element M and metal element M2 contained in the ion conductive material.

[0033] The ion-conductive material of the present embodiment may contain a compound (also referred to as an alkali metal-containing halide) represented by the following composition formula (1), or may be a compound represented by the following composition formula (1): α M βX γ D κ Z δ E η O ε ... (1) (In the formula, A is an alkali metal element, M is the above-mentioned tetravalent metal element M, X is the above-mentioned dopant element X, D is the above-mentioned divalent metal element D, Z is a halogen element, and 1≦α≦3, 0.01≦β≦1.5, 0≦γ≦0.5, 2≦δ≦5, 0.1<κ≦1.5, 0.5≦ε≦2.)

[0034] In the composition formula (1), α may be, for example, 1.1 to 2.5, 1.2 to 2.3, or 1.3 to 2.2. The upper and lower limits for α can be combined in any desired manner.

[0035] In the above composition formula (1), β may be, for example, 0.05 to 1.2, or 0.08 to 1. The upper and lower limits for β can be combined in any desired manner.

[0036] In the above composition formula (1), γ may be, for example, 0.01 to 0.3, 0.02 to 0.2, or 0.08 to 0.15. The upper and lower limits for γ can be combined in any desired manner.

[0037] In the composition formula (1), δ may be, for example, 2 to 4, or 2.1 to 3.8. The upper and lower limits for δ can be combined in any desired manner.

[0038] In the composition formula (1), ε may be, for example, 0.7 to 1.8, or 0.8 to 1.5. The upper and lower limits for ε can be combined in any desired manner.

[0039] In the above composition formula (1), κ may be, for example, 0.15 to 1.2, or 0.2 to 1. The upper and lower limits for κ can be combined in any desired manner.

[0040] In the above composition formula (1), E is an element other than A, M, X, D, Z, and O, and may be an element added or mixed in addition to the essential elements. Examples of E include C, B, and N.

[0041] In the above composition formula (1), η may be, for example, 0 to 0.1, 0 to 0.01, or 0 to 0.001, or may be substantially 0.

[0042] Specific examples of the ion conductive material according to this embodiment include Li ２ Zr ０．５ Mg ０．５ Cl ３ O, Li ２ Zr ０．７５ Mg ０．２５ Cl ３．５ O, Li ２ Zr ０．１ Mg ０．９ Cl ２．２ O, Li ２．１ Zr ０．５ Mg ０．５ Cl ３ O (SO ４ ) ０．１ , Li ２ Zr ０．２５ Sr ０．７５ Cl ２．５ O, Li ２ Zr ０．５ Ba ０．５ Cl ３ O, and Li １．４ Ta ０．５ Mg ０．５ Cl ３．５ O １．４ Examples of compounds include compounds having the following composition formulas:

[0043] The method for producing the ion-conductive material of this embodiment is not particularly limited, but may be, for example, a production method including a step of subjecting raw materials to ball milling.

[0044] The raw material is not particularly limited, and may be a compound containing any of an alkali metal element, a metal element M, a halogen element, a divalent metal element D, and an oxygen element. The raw material is selected so that the ion-conductive material has a desired composition. The raw material may optionally contain a metal element M2, a dopant element X, etc. For example, alkali metal sources include alkali metal halides, alkali metal oxides, and alkali metal peroxide salts. The metal element M source includes a halide of the metal element M. The divalent metal element D source includes a halide of the divalent metal element D. The metal element M2 source includes a halide of the metal element M2. The dopant element X source includes XO. ４ The raw materials may be compounds such as salts of ions and alkali metals. The raw materials are preferably mixed before being subjected to ball milling, and may be mixed in an inert atmosphere (for example, an Ar atmosphere).

[0045] The conditions for the ball mill are not particularly limited, but may be a rotation speed of 200 to 700 rpm for 10 to 100 hours. The milling time may be, for example, 1 to 72 hours, 12 to 60 hours, or 20 to 60 hours.

[0046] By performing the ball milling for the above-mentioned time, the raw materials are thoroughly mixed and the mechanochemical reaction is promoted, thereby making it possible to improve the ionic conductivity of the resulting compound.

[0047] The balls used in the ball mill are not particularly limited, but zirconia balls can be used. The size of the balls used is not particularly limited, but balls of 2 mm to 10 mm can be used.

[0048] The product (ion-conductive material) obtained by ball milling does not need to be annealed. That is, the above-mentioned manufacturing method preferably does not include an annealing step for the product obtained by ball milling. If annealing is performed, the crystallites may grow and become coarse, and the above-mentioned effect may not be obtained. Examples of the above-mentioned annealing include heating the product after ball milling at 100°C or higher, 150°C or higher, or 200°C or higher.

[0049] The ion-conductive material of this embodiment can be used as a material for electrochemical devices such as capacitors and batteries. Examples of such materials include electrolyte materials. The electrolyte may be a solid electrolyte. Examples of batteries include lithium ion batteries and sodium ion batteries, which charge and discharge by the movement of alkali metal ions between a positive electrode and a negative electrode. The ion-conductive material of this embodiment may also be used as an electrode material, and may be contained in the positive electrode or negative electrode of a battery together with an active material.

[0050] The battery of this embodiment will be described below using a lithium ion battery as an example. The lithium ion battery includes a positive electrode, a negative electrode, and an electrolyte (solid electrolyte) disposed between the positive electrode and the negative electrode. The ion-conductive material of this embodiment may be included in the electrolyte of the lithium ion battery.

[0051] The positive electrode of the lithium ion battery is not particularly limited and may contain a positive electrode active material and, if necessary, a conductive additive, a binder, etc. The positive electrode may be a layer containing these materials formed on a current collector.

[0052] Examples of the positive electrode active material include lithium-containing composite metal oxides containing lithium (Li) and at least one transition metal selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, and Cu. Examples of such lithium composite metal oxides include LiCoO ２ , LiNiO ２ , LiMn ２ O ４ , Li ２ MnO ３ , LiNi ｘ Mn ｙ Co １－ｘ－ｙ O ２ [0<x+y<1]), LiNi ｘ Co ｙ Al １－ｘ－ｙ O ２ [0<x+y<1]), LiCr ０．５ Mn ０．５ O ２ , LiFePO ４ , Li ２FeP ２ O ７ , LiMnPO ４ , LiFeBO ３ , Li ３ V ２ (P.O. ４ ) ３ , Li ２ CuO ２ , Li ２ FeSiO ４ , Li ２ MnSiO ４ Examples of positive electrode active materials containing an alkali metal element other than lithium include those in which the lithium in the lithium composite metal oxides is substituted with another alkali metal element.

[0053] The negative electrode of the lithium ion battery is not particularly limited, and may contain a negative electrode active material and, if necessary, a conductive additive, a binder, etc. Examples of the negative electrode active material include simple elements such as Li, Si, P, Sn, Si—Mn, Si—Co, Si—Ni, In, and Au, alloys or composites containing these elements, carbon materials such as graphite, and substances in which lithium ions are inserted between the layers of the carbon materials.

[0054] The material of the current collector is not particularly limited, and may be, for example, a simple metal or an alloy of metals such as Mg, Ti, Fe, Co, Ni, Cu, Zn, Pd, Pt, Ag, Au, Al, In, or Ge.

[0055] The electrolyte (solid electrolyte) disposed between the positive electrode and the negative electrode may be in the form of a layer. The solid electrolyte may have a plurality of solid electrolyte layers. For example, a configuration may be provided in which a sulfide solid electrolyte layer is included in addition to the solid electrolyte layer containing the ion-conductive material of this embodiment. A configuration may be provided in which a sulfide solid electrolyte layer is included between the solid electrolyte containing the ion-conductive material of this embodiment and the negative electrode.

[0056] The sulfide solid electrolyte is not particularly limited, but for example, Li ６ P.S. ５ Cl, Li ２ S-PS ５ , Li １０ GeP ２ S １２, Li ９．６ P ３ S １２ , Li ９．５４ Si １．７４ P １．４４ S １１．７ Cl ０．３ , Li ３ P.S. ４ Examples of solid electrolytes containing an alkali metal element other than lithium include those in which the lithium in the above specific examples of solid electrolytes is replaced with another alkali metal element.

[0057] (Example 1) Ball mill: In an argon atmosphere having a dew point of −70° C. or less (hereinafter referred to as a dry argon atmosphere), Li was mixed to obtain the composition (charge composition) shown in Table 1. ２ O, ZrCl ４ , and MgCl ２ were weighed to prepare the raw materials.

[0058] The raw materials were placed in a 50 mL zirconia pot for the planetary ball mill described below, and 65 g of zirconia balls with a diameter of 4 mm were added. The mixture was treated for 24 hours at 300 rpm to induce a mechanochemical reaction, thereby obtaining the ion-conductive material of Example 1. The ball mill was operated in a mode in which the rotation direction was alternately switched between clockwise and counterclockwise, with a 1-minute interval after every 10 minutes of rotation. Planetary ball mill: PM 400 manufactured by Verder Scientific K.K.

[0059] Example 2 An ion-conductive material was produced in the same manner as in Example 1, except that the compounding ratio of the raw materials was changed so as to obtain the charged composition shown in Table 1.

[0060] Example 3 An ion-conductive material was produced in the same manner as in Example 1, except that the compounding ratio of the raw materials was changed so as to obtain the charged composition shown in Table 1.

[0061] (Example 4) As a raw material, Li ２ O, ZrCl ４ , MgCl ２ , and LiSO ４An ion-conductive material was produced in the same manner as in Example 1, except that the compounding ratio of the raw materials was changed so as to obtain the charged composition shown in Table 1.

[0062] (Example 5) As a raw material, Li ２ O, ZrCl ４ , and SrCl ２ An ion-conductive material was produced in the same manner as in Example 1, except that the compounding ratio of the raw materials was changed so as to obtain the charged composition shown in Table 1.

[0063] (Example 6) As a raw material, Li ２ O, ZrCl ４ , and BaCl ２ An ion-conductive material was produced in the same manner as in Example 1, except that the compounding ratio of the raw materials was changed so as to obtain the charged composition shown in Table 1.

[0064] (Example 7) As a raw material, Li ２ O ２ , TaCl ５ , and MgCl ２ An ion-conductive material was produced in the same manner as in Example 1, except that the compounding ratio of the raw materials was changed so as to obtain the charged composition shown in Table 1.

[0065] Comparative Example 1: LiCl and ZrCl ４ An ion-conductive material was produced in the same manner as in Example 1, except that the blending ratio of the raw materials was changed so as to obtain the charged composition shown in Table 1.

[0066] (Comparative Example 2) As a raw material, Li ２ O, LiCl, ZrCl ４ , and MgCl ２ An ion-conductive material was produced in the same manner as in Example 1, except that the compounding ratio of the raw materials was changed so as to obtain the charged composition shown in Table 1.

[0067] <Powder X-ray Diffraction> The obtained ion-conductive material was subjected to powder X-ray diffraction measurement at 25°C to evaluate the diffraction peaks observed within the 2θ range of 10 to 20°. The results are shown in Table 1. Powder X-ray diffraction measurement was performed under the following conditions. The half-width of the peak was determined by removing the background signal and performing fitting. Measurement equipment: Ultima IV (manufactured by Rigaku Corporation) X-ray generator: CuKα radiation source, voltage 40 kV, current 40 mA X-ray detector: Scintillation counter or semiconductor detector Measurement range: Diffraction angle 2θ = 5° to 80° Scan speed: 4° / min

[0068] FIG. 1 shows X-ray diffraction charts of the ion-conductive materials of Examples 1 to 7 and Comparative Examples 1 and 2.

[0069] <Evaluation of ionic conductivity> A pressure molding die including a frame, a lower punch, and an upper punch was prepared. The frame was made of insulating polycarbonate. The upper and lower punches were both made of electronically conductive stainless steel and were electrically connected to the terminals of an impedance analyzer (S11260, manufactured by Solatron Analytical).

[0070] Using the above-mentioned pressure molding die, the ionic conductivity of the ion-conductive material was measured by the following method. First, in a dry argon atmosphere, powder of the ion-conductive material was filled onto the lower part of a punch inserted vertically from below into the hollow part of a frame mold. Then, the upper part of the punch was pressed into the hollow part of the frame mold from above, thereby applying a pressure of 370 MPa to the powder of the ion-conductive material inside the pressure molding die. After the pressure was applied, the punch was clamped from above and below with a jig to fix it, and while maintaining a constant pressure, the impedance of the ion-conductive material was measured by electrochemical impedance measurement using the above-mentioned impedance analyzer.

[0071] A Cole-Cole diagram was created from the impedance measurement results. In the Cole-Cole diagram, the real value of the impedance at the measurement point where the absolute value of the phase of the complex impedance was smallest was considered to be the resistance value to the ionic conduction of the ion-conductive material. Using this resistance value, the ionic conductivity was calculated based on the following formula (III): σ=(R ＳＥ × S / t) －１ ...(III) where, σ is the ionic conductivity, S is the contact area of ​​the ion-conductive material with the upper part of the punch (equal to the cross-sectional area of ​​the hollow part of the frame), and R ＳＥ is the resistance value of the solid electrolyte material in the impedance measurement, and t is the thickness of the ion-conductive material when pressure is applied.

[0072] Using the above method, the ionic conductivity of each ion-conductive material of the Examples and Comparative Examples was measured at five temperatures (25°C, 40°C, 60°C, 80°C, and 100°C) within the temperature range of 25°C to 100°C. The ionic conductivity (σ ２５℃ ) are shown in Table 1. Fig. 2 is a diagram showing the Arrhenius plots obtained for the ion-conductive materials of Examples 1 to 4. In Fig. 2, the plots of Example 1 and Example 2 almost overlap.

[0073] <Measurement of HCl gas generation amount> 0.2 g of each ion-conductive material was placed in a 1 L glass bottle and stored in an atmosphere of 25°C and 50% humidity for 48 hours. After 48 hours, the HCl concentration in the glass bottle was measured using a gas detector tube (hydrogen chloride detector tube No. 14L, manufactured by Gastec Corporation). The results are shown in Table 1.

[0074]

Claims

1. An ion-conductive material comprising a metal element M which is at least one of an alkali metal element, a tetravalent metal element, and a pentavalent metal element, a halogen element, a divalent metal element D, and an oxygen element, the material having a diffraction peak with a half-width of 2.0 to 10° in a 2θ angle range of 5 to 20° in an X-ray diffraction chart obtained by measurement using CuKα radiation at 25°C, and the content of the divalent metal element D is 2.5 to 18 mol%.

2. The ionically conductive material according to claim 1, wherein the divalent metal element D includes at least one element selected from the group consisting of Mg, Ca, Sr, and Ba.

3. The ionically conductive material according to claim 1 or 2, wherein the halogen element includes chlorine.

4. The ionically conductive material according to claim 1 or 2, wherein the content of said alkali metal element is 15 to 35 mol %, the content of said metal element M is 1 to 15 mol %, and the content of said halogen element is 30 to 60 mol %.

5. A solid electrolyte comprising the ion-conductive material according to claim 1 or 2.

6. A battery comprising the solid electrolyte according to claim 5.

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