Hydride ion conductor and its manufacturing method, catalyst, battery electrolyte, and battery

Abstract

Provided are: a hydride ion conductor having a composition represented by formula (1) of M1 aM2 bM3 cHxX1 yX2 z; a manufacturing method therefor; a catalyst composed of said hydride ion conductor; a battery electrolyte including said hydride ion conductor; and a battery including said battery electrolyte. In formula (1), M1 represents an alkali metal element, M2 represents Mg or an alkaline earth metal element, M3 represents a rare earth metal element, 0≤a≤1, 0≤b≤2, 0≤c≤2, 1<a+b+c≤2, 0<x<4, X1 is a halogen element, 0≤y<4, X2 is a chalcogen element, 0≤z<1 when X2 represents only oxygen, 0≤z<3 when X2 represents an element including a chalcogen element other than oxygen, 3<x+y+z≤5, and M1, M2, M3, X1, and X2 may each contain multiple kinds of elements.

Description

Technical Field

[0001] The present invention relates to a hydride ion conductor, a method for producing the same, a catalyst, an electrolyte for a battery, and a battery.

Background Art

[0002] Research on the synthesis and physical properties of compounds containing hydride ions (hydride ions, H - ) has advanced in recent years. H - is monovalent, has a high polarizability, and has a low redox potential (E 0 =-2.25 V vs SHE). Therefore, for example, applications to electrochemical devices with high energy density, intermediates to other composite anion compounds, etc. are expected. For example, as solid compounds showing high H - conduction, layered perovskite-type hydrogen oxides (La,Sr)2Li(O,H)4, BaH2 at high temperature phase, etc. are known, and it has been discussed that factors such as crystal structure and anion deficiency affect ion conduction.

[0003] Patent Document 1 describes a metal support including a transition metal and a support carrying the transition metal, wherein the support is a metal hydride represented by a specific formula. Patent Document 2 describes a hydride ion conductor having a composition represented by the general formula M 1 X M 2 y AH z O α (where M 1 is a trivalent rare earth element, M 2 is an alkaline earth metal element or Mg, A represents Li, Na, Sc, Co, Ni, Cu, Mn or Fe. 0≦x≦2; 0≦y≦2; x + y = 2; 0 < z < 4; and 1≦α<3 or 3<α<4). Patent Document 3 states that 1 atomic% or more of oxide ions contained in a titanium-containing perovskite-type oxide is hydride ion (H -)-substituted perovskite-type oxides having hydride ion conductivity are described. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 082265 [Patent Document 2] Japanese Patent Application Publication No. 2017-098067 [Patent Document 3] International Publication No. 2013 / 008705 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, various solid compounds that exhibit hydride ion conductivity have been investigated to date. However, since various physical properties are required of hydride ion conductors depending on the application in which they are used, the development of novel hydride ion conductors is desired.

[0006] An object of the present invention is to provide a novel hydride ion conductor, a catalyst comprising the hydride ion conductor, a battery electrolyte containing the hydride ion conductor, and a battery containing the battery electrolyte. [Means for solving the problem]

[0007] Representative embodiments of the present invention are described below. <1> Formula (1):M 1 a M 2 b M 3 c H x X 1 y X 2 z a hydride ion conductor having a composition represented by the formula: In formula (1), M 1represents an alkali metal element, M 2 represents Mg or an alkaline earth metal element, M 3 represents a rare earth metal element, where 0 ≦ a ≦ 1, 0 ≦ b ≦ 2, 0 ≦ c ≦ 2, 1 < a + b + c ≦ 2, 0 < x < 4, X 1 is a halogen element, where 0 ≦ y < 4, X 2 is a chalcogen element, X 2 when X represents only oxygen, 0 ≦ z < 1, X 2 when X represents an element containing a chalcogen element other than oxygen, 0 ≦ z < 3, 3 < x + y + z ≦ 5, M 1 , M 2 , M 3 , X 1 and X 2 may each contain a plurality of elements. <2> Does not contain oxygen atoms, or, for the total molar amount of X 1 and X 2 the molar amount of oxygen atoms contained is 5% or less. The hydride ion conductor according to <1>. <3> The absolute value of a + 2b + 3c - (x + y + 2z) is 1 or less. The hydride ion conductor according to <1> or <2>. <​​​​​​​​​​​​​​​​​​<9> In formula (1), 0 < y < 4, and X 1 contains F, Cl, or Br, and is the hydride ion conductor according to any one of <1> to <8>. <10> In formula (1), 0 < z < 3, and X 2 contains S or Se, and is the hydride ion conductor according to any one of <1> to <9>. <11> The hydride ion conductor has a composition represented by the following formula (1’), and is the hydride ion conductor according to any one of <1> to <10>; Formula (1’): M 1 a-δ1 M 2 b-δ2 M 3 c-δ3 H x-(δ1+2δ2+3δ3) X 1 y X 2 z In formula (1’), M 1 represents an alkali metal element, M 2 represents Mg or an alkaline earth metal element, M 3 represents a rare earth metal element, 0 ≤ a ≤ 1, 0 ≤ b ≤ 2, 0 ≤ c ≤ 2, and 1 < a + b + c ≤ 2, 0 < x < 4, X 1 is a halogen element, 0 ≤ y < 4, X 2 is a chalcogen element, X​​​​​​​​​​​​​​​​​A precursor powder containing at least one binary hydride of AH and at least one binary compound of AX is heated under a pressure condition of less than 1 GPa, The A represents an alkali metal element, Mg, an alkaline earth metal element, or a rare earth element, and the X represents a halogen element or a chalcogen element. Method for producing hydride ion conductors. <13> <1> ~ <11> A method for producing the hydride ion conductor according to any one of the above items, comprising the steps of: A step of heating a precursor powder containing at least one binary hydride of AH and at least one binary compound of AX under a pressure condition of 1 GPa or more, The A represents an alkali metal element, Mg, an alkaline earth metal element, or a rare earth element, and the X represents a halogen element or a chalcogen element. Method for producing hydride ion conductors. <14> <1> ~ <11> A catalyst comprising the hydride ion conductor according to any one of the above items. <15> <1> ~ <11> 10. A battery electrolyte comprising the hydride ion conductor according to any one of claims 1 to 9. <16> <15> A battery comprising the battery electrolyte according to claim 1. [Effects of the Invention]

[0008] According to the present invention, there are provided a novel hydride ion conductor, a catalyst comprising the hydride ion conductor, a battery electrolyte containing the hydride ion conductor, and a battery containing the battery electrolyte. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows the results of synchrotron radiation powder X-ray diffraction measurements of Ba2H3Cl, Ba2H3Br, and Ba2H3I obtained in Production Example 1. [Figure 2] 1 shows the results of synchrotron radiation powder X-ray diffraction measurement (XRD) of LaSrH 3 S obtained in Production Example 4. [Figure 3]1 shows the results of synchrotron radiation powder X-ray diffraction measurement (XRD) of Sr7H12Cl2 (Sr2H3.43Cl0.57) obtained in Production Example 5. [Figure 4] 1 shows the results of electrochemical impedance measurements (Arrhenius plots) of Ba2H3Cl, Ba2H3Br, and Ba2H3I obtained in Production Example 1, Ba1.9K0.1H2.9Cl obtained in Production Example 3, and LaSrH3S and LaBaH3S obtained in Production Example 4. [Figure 5] 1 shows the results of electrochemical impedance measurements (Arrhenius plots) of Ba2H3Cl, Ba2H3Br, and Ba2H3I obtained in Production Example 1 during temperature increase and decrease. [Figure 6] 1 shows the results of electrochemical impedance measurement (Cole-Cole plot) of Ba2H3I (200°C) obtained in Production Example 1. [Figure 7] 1 shows the results (Arrhenius plot) of electrochemical impedance measurement of Ba2H3X (X=Cl, Br, I) obtained in Production Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below. The following description of the components will be based on representative embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, unless otherwise specified, the temperature is 23° C. and the pressure is 101,325 Pa (1 atmosphere). As used herein, combinations of preferred embodiments are more preferred embodiments.

[0011] (hydride conductor) The hydride conductor of the present invention is a hydride conductor having a composition represented by the following formula (1). Formula (1):M 1a M 2 b M 3 c H x X 1 y X 2 z In formula (1), M 1 represents an alkali metal element, and M 2 represents Mg or an alkaline earth metal element, and M 3 represents a rare earth metal element, 0≦a≦1, 0≦b≦2, 0≦c≦2, and 1 <a+b+c≦2であり、0<x<4であり、X 1 is a halogen element, 0≦y<4, and X 2 is a chalcogen element, and X 2 When represents only oxygen, 0≦z<1 and X 2 When represents an element containing a chalcogen element other than oxygen, 0≦z<3, and 3 <x+y+z≦5であり、M 1 , M 2 , M 3 , X 1 and X 2 may each contain multiple elements.

[0012] The hydride conductor of the present invention is a novel hydride conductor. None of Patent Documents 1 to 3 describes a hydride conductor that corresponds to formula (1) of the present invention. Patent Document 1 describes an element such as BaH2 having the formula: XHn (wherein X represents at least one atom selected from Group 2 atoms, Group 3 atoms, and lanthanoid atoms in the periodic table, and n represents a number satisfying the formula 2≦n≦3), but this differs from the hydride ion conductor of the present invention in that it does not contain a halogen element or a chalcogen element. Patent Document 2 describes a compound of formula M 1 X M 2 y AH z O α (In the formula, M 1 is a trivalent rare earth element, M 2represents an alkaline earth metal element or Mg, A represents Li, Na, Sc, Co, Ni, Cu, Mn or Fe. 0 ≦ x ≦ 2; 0 ≦ y ≦ 2; x + y = 2; 0 < z < 4; and 1 ≦ α < 3 or 3 < α < 4.) A hydride ion conductor having a composition represented by is described, but this is different from the hydride ion conductor of the present invention in that it contains a total of three metal elements (M 1 , M 2 and A). Patent Document 3 describes a perovskite-type oxide having hydride ion conductivity in which 1 atomic% or more of oxide ions contained in a titanium-containing perovskite-type oxide are substituted with hydride ions (H-), but this is different from the hydride ion conductor of the present invention in that titanium is essential as a metal element. In addition, the hydride conductor of the present invention is considered to be excellent in hydride ion conductivity as compared with the hydride ion conductors described in any of Patent Documents 1 to 3 above by having the composition represented by the above formula (1). In particular, among the hydride conductors of the present invention, there are those that can exhibit hydride ion conductivity within or near the so-called "Norby gap", which is the limit region of the ionic conductivity of hydrogen cations due to the large charge density of hydrogen cations. Furthermore, the hydride conductor of the present invention is considered to be excellent in hydride ion conductivity even at low temperatures (for example, in a medium to low temperature range such as 300 °C or lower) as compared with the hydride ion conductors described in any of Patent Documents 1 to 3 above by having the composition represented by the above formula (1). In addition, the hydride conductor of the present invention is considered to be excellent in stability because the electron donation from hydride ions is suppressed as compared with the hydride ion conductors described in any of Patent Documents 1 to 3 above by having the composition represented by the above formula (1). Hereinafter, the details of the hydride conductor of the present invention will be described.

[0013] <M 1 , a> In formula (1), M 1represents an alkali metal element, including Li, Na, K, Rb, Cs, and Fr, with Li, Na, K, or Rb being preferred, and K being more preferred. In formula (1), a satisfies 0 ≦ a ≦ 1, preferably 0 ≦ a ≦ 0.8, and more preferably 0 ≦ a ≦ 0.5. Within the range of a, M 1 may have excellent hydride ion conductivity by containing it. Also, the aspect where a = 0 is one of the preferred aspects of the present invention.

[0014] <M 2 , b > In formula (1), M 2 represents Mg or an alkaline earth metal element, including Mg, Ca, Sr, Ba, Ra, with Ca, Sr, or Ba being preferred, and Sr or Ba being more preferred. In formula (1), b satisfies 0 ≦ b ≦ 2, preferably 0.5 ≦ b ≦ 2, more preferably 0.8 ≦ b ≦ 2, and even more preferably 1 ≦ b ≦ 2. Also, the aspect where 0 < b ≦ 2 and the above M 2 includes at least one of Ba and Sr is also one of the preferred aspects of the present invention. In the above aspect, the preferred aspect of b is as described above.

[0015] <M 3 , c > In formula (1), M 3 represents a rare earth metal element, including Sc, Y, and lanthanoids, with Sc, Y, La being preferred, and La being more preferred. Also, when the compound represented by formula (1) contains M 3 (that is, when 0 < c), it is preferred that the compound represented by formula (1) contains M 2 (that is, 0 < b). In formula (1), c satisfies 0 ≦ c ≦ 2, preferably 0 ≦ c ≦ 1.5, more preferably 0 ≦ c ≦ 1.2, and even more preferably 0 ≦ c ≦ 1. Also, 0 < c ≦ 2 and the above M 3An embodiment in which contains La is also one of the preferred embodiments of the present invention. Furthermore, an embodiment in which 0≦c≦1 and 1≦b≦2 is also one of the preferred embodiments of the present invention. In the above embodiment, an embodiment in which 0≦c≦0.5 and 1.5≦b≦2 is also one of the preferred embodiments of the present invention.

[0016] <x> In formula (1), x satisfies 0 < x < 4, preferably 1 ≤ x < 4, and more preferably 2 ≤ x ≤ 3.

[0017] <X 1 , y> In formula (1), X 1 represents a halogen element, including F, Cl, Br, I, At, etc. From the perspective of improving the mobility of hydride ions and enhancing hydride conductivity, Cl, Br, or I is preferred, and I is more preferred. In particular, when X 1 is a soft (easily changeable bond length) anion such as Cl, Br, or I, it is considered that the hydride conductivity is likely to increase. Among these, I is the most preferred because it is the softest, and Br is the next preferred because it is the second softest after I. y satisfies 0 ≤ y < 4, preferably 0 ≤ y ≤ 3, and more preferably 0 ≤ y ≤ 1. Also, an embodiment where 0 < y < 4 and the above X 1 contains F, Cl, or Br is also one of the preferred embodiments of the present invention.

[0018] <X 2 , z> In formula (1), X 2 represents a chalcogen element, including O, S, Se, Te, Po, Lv, etc. From the perspective of the mobility of hydride ions, S, Se, or Te is preferred, and S or Se is more preferred. In formula (1), when X 2 represents only oxygen, 0 ≤ z < 1, preferably 0 ≤ z ≤ 0.9, more preferably 0 ≤ z ≤ 0.8, and even more preferably 0 ≤ z ≤​​​​​​​​​​​​​may include both, but X 1 and X 2 Preferably, it contains only one of them. That is, an embodiment where 0 < y and z = 0, or an embodiment where y = 0 and 0 < z is also one of the preferred embodiments. Also, from the viewpoint of improving the conductivity of hydride ions, the hydride ion conductor of the present invention does not contain oxygen atoms, or 1 and X 2 0 Also, 0 < z < 3, and the above X 2 containing S or Se is also one of the preferred embodiments of the present invention. The molar amount of the oxygen atoms contained is more preferably 2% or less, still more preferably 1% or less, and particularly preferably 0.1% or less.

[0019] <a + b + c> In formula (1), 1 < a + b + c ≤ 2, preferably 1.5 < a + b + c ≤ 2, more preferably 1.8 < a + b + c ≤ 2, and still more preferably 1.9 < a + b + c ≤ 2. Also, an embodiment where a + b + c = 2 in formula (1) is also one of the preferred embodiments of the present invention.

[0020] <the absolute value of a + 2b + 3c - (x + y + 2z)> The absolute value of a + 2b + 3c - (x + y + 2z) in formula (1) is preferably 1 or less, more preferably 0.5 or less, and still more preferably 0.1 or less. The minimum value of the absolute value of a + 2b + 3c - (x + y + 2z) is not particularly limited and may be 0 or more. Also, an embodiment where the absolute value of a + 2b + 3c - (x + y + 2z) is 0 is also one of the preferred embodiments of the present invention.

[0021] <structure> The structure of the hydride conductor of the present invention is thought to be distorted depending on temperature conditions and the like, and it is difficult to define the structure uniquely. However, the hydride conductor of the present invention is preferably a layered compound, and the hydride conductor of the present invention is preferably a layered compound and is preferably a compound in which H, X in the formula (1) are not included. 1 and X 2 It is more preferable that the element present in the layered compound is present between the layered lattices. An example of the hydride conductor of the present invention is H, X 1 and X 2 Among these, hexagonal compounds in which elements present in the layered compound are arranged between the layered lattices are mentioned. A presumed crystal structure of Ba2H3X corresponding to the hydride ion conductor of the present invention will be described below, but the crystal structure of the hydride ion conductor of the present invention is not limited to this. [ka]

[0022] The crystal structure of Ba2H3X is an anti-Li3LaSb2 structure (space group P3m1), consisting of face-sharing octahedral layers of HBa6 and XBa6 stacked alternately along the hexagonal C axis, with an additional hydride anion in a distorted tetrahedron (HBa4). It can also be considered an anion-ordered HT-BaH2, where half of the H1s are replaced by X.

[0023] <Impurities> The hydride conductor of the present invention is M 1 , M 2 , M 3 , H, X 1 , X 2 It may contain elements different from M as inevitable impurities. 1 , M 2 , M 3 , H, X 1 , X 2 The ratio of the molar amount of the inevitable impurities contained in the hydride conductor of the present invention to the total molar amount of elements contained in the hydride conductor of the present invention is preferably 10% or less, more preferably 5% or less, even more preferably 1% or less, and particularly preferably 0.1% or less. There is no particular limitation on the lower limit of the ratio, and it may be 0%. The inevitable impurities refer to those that are inevitably mixed in during the production process, for example, because they are mixed in with raw materials.

[0024] <Defect> The hydride ion conductor having the composition represented by formula (1) may have defects. Specifically, for example, the composition formula of Ba2H3X is actually Ba 2-δ H 3-2δ It is considered that the composition has Schottky defects of Ba and H, represented by X (δ is the defect amount). The range of δ is preferably 0 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. The upper limit is not particularly limited, but can be set to, for example, 0.5. An embodiment in which δ is 0 is also one of the preferred embodiments of the present invention. That is, the hydride ion conductor having the composition represented by formula (1) is also preferably a hydride ion conductor having the composition represented by the following formula (1'). Formula (1'):M 1 a-δ1 M 2 b-δ2 M 3 c-δ3 H x-(δ1+2δ2+3δ3) X 1 y X 2 z In formula (1'), M 1 , M 2 , M 3 , a, b, c, X 1 、 X 2 、 x, y, and z are, respectively, M 1 , M 2 , M 3 , a, b, c, X 1 、 X 2 、 The meanings and preferred embodiments are the same as for x, y, and z, with the proviso that a1-δ1, b1-δ2, c1-δ3, and x-(δ1+2δ2+3δ3) are not less than 0. In formula (1'), δ1 is preferably 0 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. There is no particular upper limit, but it can be set to, for example, 0.5. An embodiment in which δ1 is 0 is also one of the preferred embodiments of the present invention. In formula (1'), δ2 is preferably 0 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. There is no particular upper limit, but it can be set to, for example, 0.5. An embodiment in which δ2 is 0 is also one of the preferred embodiments of the present invention. In formula (1'), δ3 is preferably 0 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. There is no particular upper limit, but it can be set to, for example, 0.5. An embodiment in which δ3 is 0 is also one of the preferred embodiments of the present invention. Here, in formula (1'), H, X 1 and X 2 At least one selected from the group consisting of H, X 1 and X 2 In other words, the hydride ion conductor of the present invention is a hydride ion conductor in which the atomic positions occupied by at least one other atom selected from the group consisting of H, X may be randomly occupied. 1 and X 2 Antisite defects can be obtained. The percentage of the above occupancy (ideally, among all sites that H occupies, X 1 or X 2 The ratio of sites occupied by the hydroxyl group (the ratio of sites occupied by the hydroxyl group) is preferably, for example, 10% or more, and more preferably 20% or more. The upper limit of the ratio is not particularly limited, but can be set to 50% or less. An embodiment in which the ratio is 0% is also one of the preferred embodiments of the present invention. For example, the hydride ion conductor having the composition represented by formula (1') may be a hydride ion conductor having the composition represented by formula (1''). Formula (1''):M 1 a-δ1 M 2 b-δ2 M 3 c-δ3 (H x-(δ1+2δ2+3δ3) ) H 1-α (X 1 y X 2 z ) H α (H x-(δ1+2δ2+3δ3) ) X α (X 1 y X 2 z ) X 1-α However, for example, (A) B α represents the ratio of A to the site ideally occupied by B, α. In formula (1''), M 1 , M 2 , M 3 , a, b, c, X 1 、 X 2 、 x, y, z, δ1, δ2, and δ3 are the M 1 , M 2 , M 3 , a, b, c, X 1 、 X 2 、 These have the same meanings as x, y, z, δ1, δ2, and δ3, and the preferred embodiments are also the same. α is preferably 0.1 or more, more preferably 0.2 or more. There is no particular upper limit, but it can be set to 0.5, for example. An embodiment in which α is 0 is also one of the preferred embodiments of the present invention.

[0025] <Activation energy> The activation energy of the compound represented by formula (1) is 60 kJ mol -1 Preferably, it is 55 kJ mol -1 More preferably, it is 50 kJ·mol -1 The lower limit is not particularly limited, but for example, 20 kJ mol -1 can be greater than 30 kJ mol -1 The above is preferable. It is believed that the small activation energy allows high-speed conduction of hydride anions in a lower temperature range.

[0026] <Formula (2)~Formula (4)> Among these, the compound represented by formula (1) is preferably a compound represented by any one of the following formulas (2) to (4).

[0027] Formula (2):M 2 2H x X 1 y In formula (2), M 2 represents Mg or an alkaline earth metal element, and 0 <x<4であり、X 1 is a halogen element, 0≦y<4, and 3 <x+y≦5であり、M 2 and X 1 may each contain multiple elements. In particular, Ba2H3X (X = Cl, Br, I) can exhibit hydride ion conductivity within or near the Norby gap, and can also exhibit suitable hydride ion conductivity even in a low temperature region. Furthermore, when the compound represented by formula (2) contains defects, it may be a compound represented by the following formula (2'). Formula (2'):M 2 2-δ H x-δ X 1 y In formula (2'), M 2 , X 1 , x and y are M in formula (2) 2 , X1, x, and y. However, 2-δ and x-δ cannot be 0 or less. In formula (2'), δ is preferably 0 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. The upper limit is not particularly limited, but can be, for example, 0.5. An embodiment in which δ is 0 is also one of the preferred embodiments of the present invention. Furthermore, the compound represented by formula (2') is a compound containing, so-called, H and X. 1 Antisite defects can be obtained.

[0028] Formula (3):M 1 a M 2 b H x X 1 y In formula (3), M 1 represents an alkali metal element, and M 2 represents Mg or an alkaline earth metal element, and 0 <a≦1、0<b<2であり、1<a+b≦2であり、0<x<4であり、X 1 is a halogen element, 0≦y<4, and 3 <x+y≦5であり、M 1 , M 2 and X 1 may each contain multiple elements. Furthermore, when the compound represented by formula (3) contains defects, it may be a compound represented by the following formula (3'). Formula (3'):M 1 a-δ1 M 2 b-δ2 H x-(δ1+2δ2) X 1 y In formula (3'), M 1 , M 2 , X 1 , a, b, x and y are M in formula (3). 1 , M 2 , X 1 , a, b, x, and y. However, a-δ1, b-δ2, and x-(δ1+2δ2) cannot be less than or equal to 0. In formula (3'), δ1 is preferably 0 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. There is no particular upper limit, but it can be set to, for example, 0.5. An embodiment in which δ1 is 0 is also one of the preferred embodiments of the present invention. In formula (3'), δ2 is preferably 0 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. The upper limit is not particularly limited, but can be set to, for example, 0.5. An embodiment in which δ2 is 0 is also one of the preferred embodiments of the present invention. Furthermore, the compound represented by formula (3') is a compound containing, so-called, H and X. 1 Antisite defects can be obtained.

[0029] Formula (4):M 2 b M 3 c H x X 2 z In formula (4), M 2 represents Mg or an alkaline earth metal element, and M 3 represents rare earth metal elements, and 0 <b<2、0<c<2であり、1<b+c≦2であり、0<x<4であり、X 2 is a chalcogen element, and X 2 When represents only oxygen, 0≦z<1 and X 2 When represents an element containing a chalcogen element other than oxygen, 0≦z<3, and 3 <x+z≦4であり、M 2 , M 3 and X 2 may each contain multiple elements. Furthermore, when the compound represented by formula (4) contains defects, it may be a compound represented by the following formula (4'). Formula (4'):M 2 b-δ2 M 3 c-δ3 H x-(2δ2+3δ3) X 2 z In formula (4'), M 2 , M 3 , X 2 , b, c, x and z are M in formula (4). 2 and M 3 and X 2 are the same as b, c, x, and z. However, b - δ2, c - δ3, and x - (2δ2 + 3δ3) are not each less than or equal to 0. In formula (4’), δ2 is preferably 0 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. The upper limit is not particularly limited, and for example, it can be 0.5. Also, the aspect where δ2 is 0 is also one of the preferred aspects of the present invention. In formula (4’), δ3 is preferably 0 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. The upper limit is not particularly limited, and for example, it can be 0.5. Also, the aspect where δ3 is 0 is also one of the preferred aspects of the present invention. Further, the compound represented by formula (4’) can have so-called anti-site defects of H and X 2

[0030] [Formula (2)] In formula (2), M 2 , x, X 1 , and y are respectively the same as M 2 , x, X 1 , and y in formula (1), and the preferred aspects are also the same. In formula (2), 3 < x + y ≤ 5, preferably 3.8 < x + y ≤ 5, more preferably 3.9 < x + y ≤ 4, and particularly preferably x + y = 4.

[0031] [Formula (3)] In formula (3), M 1 , M 2 , x, X 1 and y are respectively the same as M 1 , a, M 2 , b, x, X 1 and y in formula (1), and the preferred aspects are also the same. In formula (3), 0 < a ≤ 1, preferably 0.05 ≤ a ≤ 1, and more preferably 0.05 ≤ a ≤ 0.5. In formula (3), 0 < b < 2, preferably 1 < b < 2, more preferably 1 ≤ b ≤ 1.95, and even more preferably 1.5 ≤ b ≤ 1.95. In formula (3), 1 < a + b ≤ 2, preferably 1.5 < a + b ≤ 2, more preferably 1.8 < a + b ≤ 2, and even more preferably 1.9 < a + b ≤ 2. Also, the aspect where a + b = 2 is also one of the preferred aspects of the present invention. The absolute value of a + 2b - (x + y) in formula (3) is preferably 1 or less, more preferably 0.5 or less, and even more preferably 0.1 or less. The minimum value of the absolute value of a + 2b - (x + y) is not particularly limited and may be 0 or more. Also, the aspect where the absolute value of a + 2b - (x + y) is 0 is also one of the preferred aspects of the present invention.

[0032] [Formula (4)] In formula (4), M 2 , M 3 , x, X 2 and z are respectively synonymous with M <00003​​​​​​​​​​​​​​​The minimum absolute value of 2b+3c-(x+2z) is not particularly limited as long as it is equal to or greater than 0. In addition, an embodiment in which the absolute value of 2b+3c-(x+2z) is 0 is also one of the preferred embodiments of the present invention.

[0033] <Conductivity> The hydride conductivity of the hydride conductor of the present invention is 1×10 -4 S / cm or more is preferable, and 1×10 -3 The upper limit is not particularly limited, but it is preferably 1×10 -1 S / cm. The hydride conductivity of the hydride conductor of the present invention is 1×10 at 100° C. -6 S / cm or more is preferable, and 1×10 -5 The upper limit is not particularly limited, but it is preferably 1×10 -1 S / cm. The hydride conductivity is measured by the method described in the Examples below.

[0034] <Example> Specific examples of the compound represented by formula (1) include Ba2H3Cl, Ba2H3Br, Ba2H3I, Ba 1.9 K 0.1 H 2.9 Cl, LaSrH3S, LaBaH3S, Ba2H 3.5 I 0.5 , La 0.1 Ba 1.9 H 3.1 Cl, SrH 3.4 Cl 0.6 (Sr7H 12 Cl2), but is not limited to these.

[0035] <Method for producing the compound represented by formula (1)> An example of a method for producing a hydride ion conductor having the composition represented by formula (1) is shown below. However, the method for producing the hydride ion conductor having the composition represented by formula (1) is not particularly limited as long as it has the composition represented by formula (1), and it may be obtained by other production methods.

[0036] A first aspect of the method for producing a hydride ion conductor of the present invention comprises a step of heating a precursor powder containing at least one binary hydride of AH and at least one binary compound of AX under a pressure condition of less than 1 GPa, wherein A represents an alkali metal element, Mg, an alkaline earth metal element, or a rare earth element, and X represents a halogen element or a chalcogen element. According to the first embodiment, the hydride ion conductor of the present invention is obtained as a powder sample. The precursor powder can be obtained by thoroughly mixing, for example, a binary hydride of AH (e.g., NaH, BaH2, LaH3, etc.) and a binary compound of AX (e.g., NaBr, BaI2, La2S3, etc.). The binary hydrides of AH and the binary compounds of AX may each be used alone or in combination of two or more. For example, by using BaH2 and KH in combination as a binary hydride of AH, M in formula (1) can be obtained. 1 Let K be 2 A hydride conductor containing Ba can be obtained. The heating is preferably carried out in an inert gas atmosphere such as hydrogen gas, nitrogen gas, or argon gas, or a mixed gas atmosphere of these, or in vacuum. In addition, it is preferable that the handling of the binary hydride of AH and the binary compound of AX in the mixing for preparing the precursor powder is also carried out under the inert gas atmosphere or under vacuum. The heating is carried out, for example, at 200 to 1600° C. for 0.1 to 100 hours. The heating means is not particularly limited, and heating may be carried out by a known method. The pressure condition during the heating may be less than 1 GPa, preferably 10 to 500 kPa, more preferably 50 to 200 kPa, and even more preferably 90 to 110 kPa. It is also preferable to perform the heating under normal pressure (101.325 kPa). The pressure conditions can be applied by a known method such as a pressure generator, and are not particularly limited. When the reaction is carried out under normal pressure, the reaction can be carried out without any particular adjustment of the pressure.

[0037] A second embodiment of the method for producing a hydride ion conductor of the present invention comprises a step of heating a precursor powder containing at least one binary hydride of AH and at least one binary compound of AX under a high-pressure condition of 1 GPa or more, wherein A represents an alkali metal element, Mg, an alkaline earth metal element, or a rare earth element, and X represents a halogen element or a chalcogen element. According to the second embodiment, the hydride ion conductor of the present invention is obtained as a powder sample. The pressure under the high-pressure conditions may be 1 GPa or more, preferably 2 GPa or more, more preferably 3 GPa or more, and even more preferably 5 GPa or more. The upper limit of the pressure is not particularly limited, but can be, for example, 20 GPa or less. The pressure conditions can be applied by a known method such as a pressure generator, and are not particularly limited. In this way, when heating is performed under high pressure conditions, there is an advantage that the composition of the hydride ion conductor can be easily controlled. For example, the hydride ion conductor of the present invention can be said to be a mixed anion system containing hydride ions and at least one other anion. In such mixed anion systems, there may be differences in volatility between the anions. Therefore, by performing the heating under the high-pressure conditions, the volatilization of the anions is suppressed, making it easier to control the composition. Furthermore, compounds that are difficult to synthesize under low-pressure conditions, such as atmospheric pressure, may be able to be synthesized under high-pressure conditions, which is thought to broaden the range of compositions that can be synthesized. The binary hydride of AH, the binary compound of AX, the heating conditions, etc. are the same as those in the first embodiment. In the second embodiment, a hydrogen generating agent (for example, a mixture of NaBH4 and Ca(OH)2) may be added to the precursor powder to compensate for hydrogen deficiency in the product or to control the synthesis atmosphere.

[0038] The hydride ion conductor of the present invention may be produced in a powder state and then compressed into pellets for use, or may be mixed with a known binder or the like for use in the form of a thick film.It may also be used in the form of a thin film by a deposition process such as sputtering.

[0039] (catalyst) The catalyst of the present invention is a catalyst comprising the hydride ion conductor of the present invention. The hydride ions contained in the hydride ion conductor of the present invention have a high electron donating ability, and therefore it is expected that the hydride ion conductor will be used as a highly efficient catalyst in various syntheses. For example, it is thought that in the reaction between a hydride ion conductor and nitrogen molecules, the hydride ion donates an electron, breaking the triple bond in the nitrogen molecule, and then releases an electron, forming a nitrogen-hydrogen ring bond in the hydride ion conductor. Because it is possible to break the strong triple bond between nitrogen atoms, this conductor could be used as a catalyst for synthesizing ammonia from nitrogen molecules (nitrogen gas), for example. Furthermore, when considering general hydrogenation reactions, including ammonia synthesis reactions, the catalyst of the present invention is considered to be able to promote the diffusion of hydrogen atoms strongly adsorbed on the surface of the promoter particles and hydride ions within the catalyst particles due to its excellent hydride ion conductivity, thereby reducing hydrogen poisoning, which is a cause of deterioration of general hydrogenation catalysts. In this way, the ability to promote the diffusion of hydride ions on the catalyst surface and inside the catalyst makes it possible to use the catalyst as a highly efficient, long-life hydrogenation catalyst. Regarding the use of the hydride ion conductor as a catalyst, other than the use of the hydride ion conductor of the present invention, reference can be made to, for example, the description in Science 28 Jun 2013: Vol. 340, Issue 6140, pp. 1549-1552.

[0040] (battery electrolyte, battery) The battery electrolyte of the present invention contains the hydride ion conductor of the present invention, and is preferably a battery electrolyte consisting of the hydride ion conductor of the present invention. The battery electrolyte of the present invention is preferably a solid electrolyte. The battery electrolyte of the present invention may further contain other solid electrolytes such as inorganic solid electrolytes and organic solid electrolytes. The specific mode of use as a battery electrolyte is not particularly limited in the present invention, and a method known to those skilled in the art can be selected or adapted.

[0041] The battery of the present invention comprises the battery electrolyte of the present invention. The battery of the present invention is preferably a secondary battery. The battery of the present invention is preferably an all-solid-state battery. The battery of the present invention is preferably a battery that uses hydride ions as a charge carrier, and more preferably a fuel cell. Examples of such batteries include hydride ion secondary batteries and ammonia fuel cells. The components of the positive electrode, negative electrode, etc. in the battery are not particularly limited, and known components can be used. The hydride ion conductor of the present invention is chemically stable and has excellent hydride ion conductivity, and is therefore considered to be usable as a high-potential, high-capacity, and highly stable energy device.

[0042] An example of the battery of the present invention is a battery using TiH2 for the positive electrode, Ti for the negative electrode, and the hydride conductor of the present invention for the solid electrolyte. In the battery, the electromotive force is generated by the following electrode reaction at the positive and negative electrodes: - It is believed that the hydrogen is conducted by the hydride conductor of the present invention and is absorbed into the Ti electrode. For details of the configuration of a battery using a hydride conductor other than the use of the hydride conductor of the present invention, reference can be made to, for example, the description in Science, 18 Mar. 2016: Vol. 351, Issue 6279, pp. 1314-1317. [ka] [Example]

[0043] The features of the present invention will be explained in more detail below with reference to the following Production Examples and Examples. The materials, processing details, processing procedures, etc. shown below can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the Production Examples or Examples shown below.

[0044] <Production Example 1: Synthesis of Ba2H3X (X = Cl, Br, or I) by atmospheric pressure synthesis method> BaH2 and BaX2 (X = Cl, Br, or I) were mixed in a mass ratio of 1:3. The pelletized sample was sealed in a vacuumed quartz tube. It was heated in an electric furnace at 650°C for 20 hours. Because BaH2 and the product are very unstable in air, the sample was handled in a glove box with a N2 atmosphere.

[0045] <Production Example 2: Synthesis of Ba2H3X (X = Cl, Br, or I) by high-pressure synthesis method> BaH2 and BaX2 (X = Cl, Br, or I) were mixed in a 1:3 molar ratio. The pelletized sample was loaded into a high-pressure synthesis cell. The high-pressure synthesis cell used a hollow pyrophyllite block as the pressure medium, with a graphite sleeve inside as a heat source. To prevent contact between the graphite sleeve and the sample, a BN sleeve was placed inside, and the sample pellet was loaded inside that. A pressure of 1 GPa was applied to the high-pressure synthesis cell using a cubic anvil-type high-pressure generator. After reaching the required pressure, the cell was heated to temperatures between 600 and 900°C and maintained at that temperature for 1 hour. Because BaH2 and the products are highly unstable in air, the samples were handled in a glove box with a N2 atmosphere.

[0046] <Production Example 3: Ba 1.9 K 0.1 H 2.9 Synthesis of Cl by high-pressure synthesis method> BaH2, BaCl2, and KH were mixed in a mass ratio of 28:10:2. The pelletized sample was loaded into a high-pressure synthesis cell. The high-pressure synthesis cell used a hollow pyrophyllite block as the pressure medium, with a graphite sleeve inside as the heat source. To prevent contact between the graphite sleeve and the sample, a BN sleeve was placed inside, and the sample pellet was loaded inside that. A pressure of 1 GPa was applied to the high-pressure synthesis cell using a cubic anvil-type high-pressure generator. After reaching the required pressure, the cell was heated to temperatures between 600 and 900°C and held there for 1 hour. Because BaH2, KH, and the products are highly unstable in air, the samples were handled in a glove box with a N2 atmosphere.

[0047] <Production Example 4: Synthesis of LaAHS (A = Sr and Ba)> As starting materials, the following two different combinations of materials were used: i) La2S3, LaH 3-x , AH2 (A = Sr and Ba) in a substance ratio of 1:1:3 ii) LaH 3-x , AS (A = Sr and Ba) in a substance ratio of 1:1 The starting materials i) or ii) were mixed at a predetermined molar ratio, and the pelletized sample was filled into a cell for high-pressure synthesis. The cell for high-pressure synthesis used a hollow pyrophyllite block as the pressure medium, and a graphite sleeve was installed inside as a heat source. To avoid contact between the graphite sleeve and the sample, a BN sleeve was further placed inside, and the sample pellet was filled into the inside thereof. LaH 3-x To compensate for the hydrogen deficiency of, a hydrogen generator was used. A powder obtained by mixing NaBH4 and Ca(OH)2 at a molar ratio of 1:2 was pelletized and filled into the cell for high-pressure synthesis. At this time, a BN pellet was interposed to avoid direct contact with the sample. Using a cubic anvil type high-pressure generator, a pressure of 1 to 3 GPa was applied to the cell for high-pressure synthesis. After reaching the predetermined pressure, it was heated to a temperature of 600 to 900 °C and held for 1 hour. LaH 3-x , AH2, and the product are very unstable in the atmosphere, so the sample was handled in a glove box under a N2 atmosphere.

[0048] <Production Example 5: Synthesis of Sr7H 12 Cl2(Sr2H 3.43 Cl 0.57 ) SrH2 and SrCl2 were mixed at a molar ratio of 6:1. The pelletized sample was sealed in a vacuumed quartz tube. It was heated in an electric furnace under the conditions of holding at 650 °C for 20 hours. Since SrH2 and the product are very unstable in the atmosphere, the sample was handled in a glove box under a N2 atmosphere.

[0049] <Production Example 6: Synthesis of Ba2H3X halogen mixture (X = Cl, Br, I)> BaH2, BaCl2, BaBr2, and BaI2 were mixed at a molar ratio of 3:x:y:1-(x + y) (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ x + y ≤ 1). The pelletized sample was sealed in a vacuumed quartz tube. It was heated in an electric furnace under the conditions of holding at 650 °C for 20 hours. Since BaH2 and the product are very unstable in the atmosphere, the sample was handled in a glove box under a N2 atmosphere.

[0050] <XRD measurement results> The results of synchrotron radiation powder X-ray diffraction (XRD) measurements of Ba2H3Cl, Ba2H3Br, and Ba2H3I obtained in Production Example 1 are shown in Figure 1. In Figure 1, the vertical axis represents the diffraction intensity, and the horizontal axis represents the diffraction angle. Furthermore, the a-axis length (a (Å)) and c-axis length (c (Å)) were calculated for Ba2H3Cl, Ba2H3Br, and Ba2H3I obtained in Production Example 1, and Ba2H3Cl obtained in Production Example 2, and are listed in Table 1. In addition, the entries in the column labeled "ICSD" in Table 1 are values ​​listed in the Inorganic Crystal Structure Database (ICSD) for each compound. The results shown in Table 1 show that the c-axis length values ​​differ from those listed in the ICSD whether synthesized at normal pressure or high pressure. The results of synchrotron radiation powder X-ray diffraction (XRD) measurement of LaSrH3S obtained in Production Example 4 are shown in Figure 2, and the results of Sr7H 12 Cl2(Sr2H 3.43 Cl 0.57 The results of synchrotron radiation powder X-ray diffraction (XRD) measurements of the above compounds are shown in FIG. Figure 2 shows the Miller index corresponding to each peak. In Figure 3, SrO is presumed to be contained in the starting material SrH2 (purity 99.5%). Kapton tape is an air-blocking tape used when measuring air-labile samples. [Table 1]

[0051] Table 2 below shows the lattice constants obtained by LeBail analysis using X-ray diffraction data of a powder sample of the Ba2H3X halogen mixture (X=Cl, Br, I) obtained in Production Example 6. Table 2 also lists data for single crystals that have already been reported for comparison. The Ba2H3X halogen mixture (X = Cl, Br, I) obtained in Production Example 6 contains a considerable amount of Ba 2+ and 2H - contains a Schottky defect. [Table 2]

[0052] <Electrochemical impedance measurement> The sample pellets (4-10 mm in diameter, 1-3 mm in thickness) obtained during synthesis were used directly for conductivity measurements. Au or Mo electrodes were attached to both sides of the sample pellet by evaporation or sputtering. Electrochemical impedance measurements were performed using a Bio-Logic VSP-300 in a hydrogen atmosphere, over a frequency range of 0.1-10 MHz, during the heating and cooling process from room temperature to 400°C.

[0053] FIG. 4 shows the Ba2H3Cl, Ba2H3Br, and Ba2H3I obtained in Production Example 1, and the Ba 1.9 K 0.1 H 2.9 1 shows the results (Arrhenius plots) of electrochemical impedance measurements of Cl, LaSrH 3 S obtained in Production Example 4, and LaBaH 3 S. For comparison, Figure 4 also shows BaH2 and La 0.6 Sr 1.4 LiH 1.6 O2, La 0.6 Sr 1.4 LiH 1.6 O2, LaH 2.52 O 0.24 , the hydride ion conductivity (Arrhenius plot) of LaHO was described. From the above results, it is clear that the hydride ion conductor of the present invention has high hydride ion conductivity, and that the hydride ion conductor synthesized by the synthesis method under atmospheric pressure has particularly excellent hydride ion conductivity. In particular, it is clear that the hydride ion conductor synthesized in Production Example 1 is capable of hydride conduction even in a low temperature range of 100°C or less.

[0054] FIG. 5 shows the results (Arrhenius plots) of electrochemical impedance measurements of Ba2H3Cl, Ba2H3Br, and Ba2H3I obtained in Production Example 1 during temperature increase (FIG. 5A) and temperature decrease (FIG. 5B). Table 3 also shows the hydride ion conductivity at 300° C. and activation energy for each compound. The measurement conditions were as follows: Measurement was carried out under a H2 atmosphere. Measurement voltage: 500mV Frequency range: 7MHz to 0.1Hz Electrodes: Au electrode / sample / Au electrode Heating method: IR heater FIG. 6 shows the results of electrochemical impedance measurement (Cole-Cole plot) of Ba2H3I (200° C.) obtained in Production Example 1. [Table 3]

[0055] FIG. 7 shows the results of electrochemical impedance measurement (Arrhenius plot) of Ba2H3X (X=Cl, Br, I) obtained in Production Example 6. Table 4 also shows the hydride ion conductivity and activation energy at 300°C for each compound. In samples with any halogen mixing ratio, a stable hydride ion conductivity of 10 -3 It exhibited high ionic conductivity exceeding 100 S / cm (300°C). [Table 4]

[0056] From the above results, it can be seen that in the present compounds, the larger the ionic radius of the halogen ion, the higher the hydride ion conductivity and the smaller the activation energy.

[0057] From the above results, it was confirmed that the hydride conductor represented by formula (1) of the present invention has hydride conductivity. [Industrial Applicability]

[0058] The hydride ion conductor of the present invention is a composition that is expected to be used in various fields such as chemical synthesis and energy devices. Therefore, the present invention has high industrial applicability.< / x>

Claims

1. A hydride ion conductor having a composition represented by formula (1'): M 1 a-δ1 M 2 b-δ2 M 3 c-δ3 H x-(δ1+2δ2+3δ3) X 1 y X 2 z; In formula (1'), M 1 represents an alkali metal element, M 2 represents Mg or an alkaline earth metal element, M 3 represents a rare earth metal element, 0≦a≦1, 0≦b≦2, 0≦c≦2, 1<a+b+c≦2, 0<x<4, X 1 is a halogen element, 0≦y<4, X 2 is a chalcogen element, when X 2 represents only oxygen, 0≦z<1, when X 2 represents an element containing a chalcogen element other than oxygen, 0≦z<3, 3<x+y+z≦5, and M 1 , M 2 , M 3 , X 1 and X 2 may each contain a plurality of elements, δ1 is 0.1 or more, δ2 is 0.1 or more, δ3 is 0.1 or more, and a1-δ1, b1-δ2, c1-δ3, and x-(δ1+2δ2+3δ3) are not less than 0.

2. does not contain oxygen atoms or X １ and X ２ 2. The hydride ion conductor according to claim 1, wherein the molar content of oxygen atoms is 5% or less based on the total molar content of

3. 3. The hydride ion conductor according to claim 1, wherein the absolute value of a+2b+3c-(x+y+2z) is 1 or less.

4. It is a layered compound, and H, X in the formula (1) １ and X ２ 4. The hydride ion conductor according to claim 1, wherein the element present in the layered compound is present between the layered lattices.

5. 5. The hydride ion conductor according to claim 1, wherein a=0 in formula (1).

6. In formula (1), 0<b≦2, and ２ 6. The hydride ion conductor according to claim 1, wherein contains at least one of Ba and Sr.

7. In formula (1), 0<c≦2, and ３ The hydride ion conductor according to any one of claims 1 to 6, wherein contains La.

8. 8. The hydride ion conductor according to claim 1, wherein in formula (1), 0≦c≦1 and 1≦b≦2.

9. In formula (1), 0<y<4, and １ The hydride ion conductor according to any one of claims 1 to 8, wherein comprises F, Cl or Br.

10. In formula (1), 0<z<3, and ２ The hydride ion conductor according to any one of claims 1 to 9, wherein contains S or Se.

11. A method for producing the hydride ion conductor according to any one of claims 1 to 10, comprising the steps of: A step of heating a precursor powder containing at least one hydride composed of a binary system of A-H and at least one compound composed of a binary system of A-X under a pressure condition of less than 1 GPa, A represents an alkali metal element, Mg, an alkaline earth metal element, or a rare earth element, and X represents a halogen element or a chalcogen element. Method for producing hydride ion conductors.

12. A method for producing the hydride ion conductor according to any one of claims 1 to 10, comprising the steps of: a step of heating a precursor powder containing at least one hydride composed of a binary system of A-H and at least one compound composed of a binary system of A-X under a pressure condition of 1 GPa or more, A represents an alkali metal element, Mg, an alkaline earth metal element, or a rare earth element, and X represents a halogen element or a chalcogen element. Method for producing hydride ion conductors.

13. A catalyst comprising the hydride ion conductor according to any one of claims 1 to 10.

14. A battery electrolyte comprising the hydride ion conductor according to any one of claims 1 to 10.

15. A battery comprising the battery electrolyte of claim 14.

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