Solid electrolyte, laminate, and fuel cell

Abstract

One aspect of the present disclosure provides a solid electrolyte having a perovskite-type crystal structure, the solid electrolyte having a mother crystal represented by the general formula: AMaO3-delta, and an element Mb that solid-solubilizes a portion of Ma in the mother crystal, the mother crystal being a crystal having a value of greater than 0 and less than 1.568, the slope in a graph shows the relationship between the change in lattice volume when Mb is dissolved in a perovskite crystal represented by AMaO3-delta and the replacement solid solution ratio of Mb. The slope in a graph shows the relationship between the change in lattice volume when Mb is dissolved in a solid in a crystal represented by AMaO3 in which the [delta] of the perovskite crystal is filled with an oxygen atom and the replacement solid solution ratio of Mb.

Description

Technical Field

[0001] This disclosure relates to solid electrolytes, laminates, and fuel cells. Background Technology

[0002] Fuel cells are known to be classified according to the type of electrolyte, including alkaline electrolyte fuel cells, phosphate fuel cells, solid polymer fuel cells, and solid oxide fuel cells. Among them, solid oxide fuel cells have attracted much attention because they do not use expensive catalysts such as platinum and have high power generation efficiency.

[0003] However, solid oxide fuel cells have not yet become widespread due to their typically high operating temperatures of 700–1000°C, requiring preheating for operation, and the need for durable constituent materials. Therefore, research has been conducted on using perovskite-structured oxides as proton-conducting oxides (which also function as electrolytes) to lower the operating temperature. For example, Patent Document 1 discloses a solid electrolyte laminate formed from barium zirconate with added yttrium.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2013-206703 Summary of the Invention

[0005] The problem that the invention aims to solve The purpose of this disclosure is to provide a solid electrolyte that exhibits excellent proton diffusion performance in the intermediate temperature range of 300–400°C. Furthermore, the purpose of this disclosure is to provide a laminate containing the aforementioned solid electrolyte. Additionally, the purpose of this disclosure is to provide a fuel cell that performs excellently in the intermediate temperature range.

[0006] Methods for solving problems Regarding the diffusion of protons in solid electrolytes, it is believed that it occurs by sequentially jumping through the electron cloud surrounding oxygen atoms in a perovskite-type crystal represented by the general formula AMaO3. Therefore, it is thought that the diffusion properties of protons can be controlled by lowering the energy barrier experienced by the protons during this migration. The inventors of this application have obtained the following new insight through research: as a means of lowering the aforementioned energy barrier, the added element (Mb) is dissolved in AMaO3 containing oxygen vacancies within the crystal. 3-δ It is important to consider crystals as parent crystals that exhibit similar behavior to the lattice volume change in the case of perovskite crystals, where Mb is dissolved in oxygen vacancies and filled, to fill these lattice volumes. More specifically, it is conceivable that AMaO3... 3-δ The perovskite crystal represented by AMaO3, and the perovskite crystal represented by AMaO3 (here, in AMaO...) 3-δ(The constituent elements and composition are consistent with AMaO3, except for oxygen vacancies). The vertical axis is set to the lattice volume of each crystal, and the horizontal axis is set to the addition ratio of element Mb. When obtaining the ratio of the rate of change of lattice volume (i.e., the slope) in a graph plotting the relationship between lattice volume and the Mb addition ratio, it is important to use a crystal with a value less than a specified value as the parent crystal. Furthermore, it was found that the rate of change of lattice volume exhibits the same trend regardless of the presence or absence of oxygen vacancies, which corresponds well to the decrease in the activation energy of proton diffusion and the increase in the proton diffusion coefficient. This disclosure is based on the above-mentioned new insights. It should be noted that the change in lattice volume is related to the change in the lattice length per unit lattice in the perovskite crystal. A small change in lattice length means that even with the addition of Mb, there will be no large change in the unit lattice. This indicates a crystal that can absorb environmental changes caused by the addition of Mb, and can also be described as a crystal with excellent flexibility.

[0007] This disclosure provides one aspect of... the following [1]

[0008] [1] A solid electrolyte having a perovskite-type crystal structure, wherein the solid electrolyte has the following characteristics: (General formula: AMaO) 3-δ (In the general formula, A represents the A-site element in the perovskite structure, Ma represents the B-site element in the perovskite structure, and δ is a value less than 3) represents the parent crystal, and the element Mb in which a portion of Ma in the parent crystal is replaced by solid solution. Wherein, the mother crystal is | | / | Crystals with a value greater than 0 and less than 1.568, To demonstrate how Mb can be dissolved in AMaO 3-δ The slope in the graph representing the relationship between the change in lattice volume and the Mb substitution solution ratio in perovskite crystals. The slope in the graph shows the relationship between the change in lattice volume and the substitutional solid solution ratio of Mb when Mb is dissolved in a crystal represented by AMaO3, which is obtained by filling the δ-space of the perovskite crystal with oxygen atoms.

[0009] When the parent crystal is hard, the above-mentioned | | / | The value of | increases, meaning that the energy barrier for proton migration changes significantly with the addition of Mb. In contrast, for the aforementioned solid electrolytes, the parent crystal becomes the aforementioned | | / | The value of | is within the range specified above. For a solid electrolyte with this structure, the energy barrier for proton migration is reduced in the potential field generated by the overlap of electron clouds around oxygen. Therefore, the aforementioned solid electrolyte can become a solid electrolyte with excellent proton diffusion performance.

[0010] One aspect of this disclosure provides the following [2] to [9].

[0011] [2] As described in [1], the solid electrolyte is composed of the general formula: A(Ma 1-y Mb y O 3-δ (y is a value greater than 0 and less than 1, and δ is a value less than 3) represents this.

[0012] [3] A solid electrolyte as described in [1] or [2], wherein the ionic radius of A is set as r. A Let r be the weighted average of the ionic radii of Ma and Mb based on the elemental presence ratio. M At that time, (r) M / r A The value of ) + C is 0.24 to 0.54, where C is C = 0.55 × r A -0.89 represents the value.

[0013] [4] The solid electrolyte as described in any one of [1] to [3] has a lattice volume of 70.678 × 10⁻⁶. -3 nm 3 Above 85.052×10 -3 nm 3 the following.

[0014] [5] The solid electrolyte as described in any one of [1] to [4] has a proton conductivity of 1.0 × 10⁻⁶. -3 Scm -1 above.

[0015] [6] A solid electrolyte as described in any one of [1] to [5], wherein A is at least one selected from the group consisting of Ba, Sr, Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Li, Na, K, Rb, Cs and Mg. Ma and Mb are each selected from at least one of the following groups: Ti, Zr, Hf, Sn, Pb, Bi, Si, Ge, Ga, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y, Lu, In, Sc, V, Nb, Ta, Cr, Mo, W, Sb, Mg, Al, As, and Re.

[0016] [7] The solid electrolyte as described in any one of [1] to [6], which is composed of the general formula: BaSn 1-y Sc y O 3-δ (y represents values ​​from 0.2 to 0.7, δ represents values ​​from 0.2 to 3), General formula: BaTi 1-y Sc y O 3-δ (y represents values ​​from 0.2 to 0.8, δ represents values ​​from 0 to 3), or general formula: BaTi 1-y-x Sn y Sc x O 3-δ (y represents a value of 0.05 to 0.15, x represents a value of 0.2 to 0.8, and δ represents a value of 0 to 3) represents.

[0017] [8] A laminate comprising a first electrode, an electrolyte membrane disposed on the first electrode, and a second electrode disposed on the electrolyte membrane on the side opposite to the first electrode side. The electrolyte membrane comprises the solid electrolyte according to any one of claims 1 to 7.

[0018] [9] A fuel cell having the stack described in [8].

[0019] Invention Effects According to this disclosure, a solid electrolyte that exhibits excellent proton diffusion performance in a mid-temperature region of 300–400°C can be provided. Furthermore, according to this disclosure, a laminate containing the aforementioned solid electrolyte can be provided. Additionally, according to this disclosure, a fuel cell that operates excellently in a mid-temperature region can be provided. Attached Figure Description

[0020] [ Figure 1 ] Figure 1 A graph showing the relationship between scandium addition ratio and lattice volume for various perovskite crystals.

[0021] [ Figure 2 ] Figure 2 The graph illustrates the relationship between the proton diffusion coefficient of the solid oxides prepared in the examples and comparative examples, the activation energy related to proton diffusion, and the scandium addition ratio.

[0022] [ Figure 3 ] Figure 3 To illustrate the proton conductivity of the solid oxides prepared in the examples and comparative examples and the properties of the parent crystals constituting the various solid oxides... / A diagram showing the relationships between them.

[0023] [ Figure 4 ] Figure 4A graph showing the results of proton conductivity measurements for the solid electrolyte prepared in Example 1.

[0024] [ Figure 5 ] Figure 5 A graph showing the evaluation results of the chemical stability of the solid electrolyte for Example 1.

[0025] [ Figure 6 ] Figure 6 A graph showing the results of the proton diffusion coefficient measurement for the solid electrolyte of Example 1.

[0026] [ Figure 7 ] Figure 7 A graph showing the results of performance evaluation of the solid electrolyte of Example 1 as an electrolyte for solar cells.

[0027] [ Figure 8 ] Figure 8 A graph showing the evaluation results for the solid electrolyte of Example 3. Detailed Implementation

[0028] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings, as appropriate. However, the following embodiments are merely examples for illustrating the present disclosure and are not intended to limit the present disclosure to the following. Unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships shown in the accompanying drawings. The dimensional ratios of the elements are not limited to those shown in the drawings.

[0029] Unless otherwise specified, the materials exemplified in this specification may be used alone or in combination of two or more. Regarding the content of each component in the composition, in the case of multiple substances that are components of the composition, unless otherwise specified, the content refers to the total amount of those substances present in the composition. Furthermore, in this specification, the numerical range indicated by "~" refers to the range including the values ​​before and after "~" as the minimum and maximum values, respectively.

[0030] One embodiment of a solid electrolyte is a solid electrolyte having a perovskite-type crystal structure, which has the general formula: AMaO 3-δ The formula represents the parent crystal and the element Mb in which a portion of Ma in the parent crystal is replaced by a solid solution. In the above formula, A represents the A-site element in the perovskite structure, Ma represents the B-site element in the perovskite structure, and δ is a value less than 3. In the above formula, A, Ma, and Mb are different elements, and O represents oxygen.

[0031] The parent crystal in the above-mentioned solid electrolyte can be | | / | Crystals with a value greater than 0 and less than 1.568, where, To demonstrate how Mb can be dissolved in AMaO 3-δ The slope in the graph representing the relationship between the change in lattice volume and the Mb substitution solution ratio in perovskite crystals. The slope of the graph shows the relationship between the change in lattice volume and the substitutional solid solution ratio of Mb when Mb is dissolved in a crystal represented by AMaO3 obtained by filling the δ-axis of the above perovskite crystal with oxygen atoms. The above graph sets the vertical axis to the lattice volume (nm) of each crystal. 3 The graph is created by setting the horizontal axis to the addition ratio of element Mb.

[0032] The above | | / | The upper limit of the value of | can be, for example, below 1.500, below 1.300, below 1.100, below 1.000, or below 0.900. By making the above | | / | The upper limit of the value of | is within the above range, which can further reduce the energy barrier felt by protons during proton conduction and improve the proton diffusion performance of solid electrolytes. The above | | / | The lower limit of the value of | can be, for example, 0.050 or higher, 0.100 or higher, 0.200 or higher, or 0.500 or higher. Regarding the above | | / | The lower limit of the value of | is within the above range, which corresponds to the lattice becoming more flexible. Therefore, the proton diffusion barrier can be further reduced, and the proton diffusion coefficient and proton conductivity are further improved.

[0033] Regarding the aforementioned parent crystal, concerning the above... and , / The value can be, for example, greater than -1 and less than 0, or greater than 0 and less than 1, greater than 0 and less than 1, 0.2 to 1.0, or 0.3 to 1.0.

[0034] The composition of the solid electrolyte and the aforementioned parent crystal in this specification can be determined by energy-dispersive X-ray diffraction (EDS) analysis. The solid solutions of A, Ma, and Mb can also be determined by EDS analysis. Furthermore, the unit cell volume of the crystal being measured is obtained by multiplying the lattice constants a, b, and c by powder X-ray diffraction at room temperature. The pseudo-cubic crystal volume (hereinafter also referred to as lattice volume) is derived by normalizing the number of perovskite units within the unit cell. A linear regression plot is generated by plotting the lattice volume obtained in the above manner relative to the Mb solid solution of the corresponding crystal, thereby determining... and It should be noted that the lattice constants a, b, and c refer to the lengths of the a-axis, b-axis, and c-axis of the crystal and parent crystal that constitute the solid electrolyte, respectively.

[0035] In this specification, when the number of constituent elements of the solid electrolyte is large or the composition formula is unclear, more specifically, the above... and the above The determination was based on the following method. First, the elements constituting the solid electrolyte and their detection concentrations were determined by energy-dispersive X-ray diffraction (EDS) analysis of the solid electrolyte. Next, the elements with a coordination number of 12 or the lanthanides, and the highest detection concentration, as reported by RD Shannon in "Revised effective ionic radii and systematic studies of interatomic distance in halides and chalcogenides," Acta Crystallograhica Section A, Volume 32, issue 5, 1976 pp. 751-767, were selected as the elements occupying the A-site in the parent crystal of the solid electrolyte (Al elements). Next, the element with the highest detected concentration among the cations whose valence is obtained by subtracting the valence of the aforementioned A1 element from "6" is selected as the element occupying the B site in the parent crystal of the solid electrolyte (Ma1 element). The element with the highest detected concentration among the elements other than the aforementioned A1 and Ma1 elements is designated as the element that replaces a portion of the Ma1 element in the parent crystal of the solid electrolyte (Mb1 element). Using the A1, Ma1, and Mb1 elements determined in this way, a plot of the A1Ma1O matrix is ​​drawn towards the parent crystal. 3-δ The relationship between lattice volume and the Mb addition ratio when Mb1 is added to AlMa1O3 was analyzed. A linearly fitted line graph was plotted, and its slope was determined. This slope was then used to determine the relationship between the lattice volume and the Mb addition ratio of the parent crystal of the solid electrolyte. and It should be noted that, in the above method, the valence of elements is represented by the following values ​​as the valence of object elements.

[0036] Ba 2+ 、Sr 2+ Ca 2+ La 3+ Ce 4+ Pr 3+ 、Nd3+ 、Sm 3+ 、Eu 3+ 、Gd 3+ 、Tb 3+ 、D y3+ 、Ho 3+ 、Er 3+ 、Tm 3+ 、Yb 3+ 、Lu 3+ 、Li 1+ 、Na 1+ 、K 1+ 、Rb 1+ 、Cs 1+ 、Mg 2+ 、Ti 4+ 、Zr 4+ 、Hf 4+ 、Sn 4+ 、Pb 4+ 、Bi 3+ 或Bi 5+ 、Si 4+ 、Ge 4+ 、Ga 3+ 、La 3 + 、Ce 4+ 、Pr 3+ 、Nd 3+ 、Sm 3+ 、Eu 3+ 、Gd 3+ 、Tb 3+ 、Dy 3+ 、Ho 3+ 、Er 3+ 、Tm 3+ 、Yb 3+ 、Y 3+ 、Lu 3+ 、In 3+ 、Sc 3+ 、V 5+ 、Nb 5 + 、Ta 5+ 、Cr 3+ 、Mo 5+ 或Mo 6+ 、W 5+ 或W 6+ 、Sb 3+ 或Sb 5+ 、Mg 2+ 、Al 3+ 、As 5+ 、Re 6+ The aforementioned parent crystal and the aforementioned solid electrolyte have a perovskite-type crystal structure. This fact can be confirmed by X-ray diffraction.

[0037] The above-mentioned solid electrolyte can be derived from the general formula: A(Ma 1-y Mb y )O 3-δ (where y is a value greater than 0 and less than 1, and δ is a value less than 3) can be represented by the general formula: A(Ma 1-y Mb y )O 3-δ (where y is a value between 0.3 and 1, and δ is a value less than 3) can be represented by the general formula: A(Ma 1-y Mb y )O 3-δ (y is a value between 0.5 and 1, and δ is a value less than 3). Because protons are introduced during use, the above solid electrolytes are sometimes also represented by the general formula: A(Ma 1-y Mb y O 3-δ H z (y is a value between 0.5 and 1, δ is a value less than 3, and z is a value that varies depending on the introduced protons)

[0038] The aforementioned A may include at least one selected from the group consisting of Ba, Sr, Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Li, Na, K, Rb, Cs, and Mg. From the viewpoint of making the lattice volume more suitable, it may be at least one selected from the group consisting of Cs, Rb, K, Na, Ba, Sr, La, Pr, and Nd. From the viewpoint of further improving the chemical stability of the obtained solid oxide, it may be at least one selected from the group consisting of Ba, Sr, La, Pr, and Nd.

[0039] The aforementioned Ma, for example, includes at least one selected from the group consisting of Ti, Zr, Hf, Sn, Pb, Bi, Si, Ge, Ga, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y, Lu, In, Sc, V, Nb, Ta, Cr, Mo, W, Sb, Mg, Al, As, and Re. From the viewpoint of making the lattice volume more suitable, it can be selected from Sn, Ti, Zr, Hf, Pb, La, Ce, Pr, Nd, Sm, Eu, G At least one of the group consisting of d, Tb, Dy, Ho, Er, Tm, Yb, Y, Lu, In, Sc, V, Nb, Ta, Cr, Mo, W, Mg and Re, which, from the viewpoint of further improving the chemical stability of the obtained solid oxide, can be Ti, Zr, Hf, Sn, Si, Ge, Ga, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y, Lu, In, Sc, V, Nb, Ta, Cr, Sb, Mg, Al and Re.

[0040] The aforementioned Mb includes, for example, at least one selected from the group consisting of Ti, Zr, Hf, Sn, Pb, Bi, Si, Ge, Ga, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y, Lu, In, Sc, V, Nb, Ta, Cr, Mo, W, Sb, Mg, Al, As, and Re. From the viewpoint of making the lattice volume more suitable, it can be selected from Sn, Ti, Zr, Hf, Pb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y, Lu, In, Sc, V, and Nb. At least one of the following can be selected from the group consisting of Ti, Zr, Hf, Sn, Si, Ge, Ga, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y, Lu, In, Sc, V, Nb, Ta, Cr, Sb, Mg, Al, and Re, from the viewpoint of further improving the chemical stability of the obtained solid oxide. At least one of the following can be selected from the group consisting of Sc, Ti, Sn, Pb, and In, from the viewpoint of improving the bulk modulus and further improving the flexibility of the crystal lattice.

[0041] Regarding A, Ma, and Mb above, if they are different elements from each other, then each of them may contain multiple elements.

[0042] More specifically, the aforementioned solid electrolyte can be, for example, derived from the general formula: BaSn 1-y Sc y O 3-δ(where y represents a value of 0.2–0.7 and δ represents a value of 0.2–3) represents a compound that can be represented by the general formula: BaTi 1-y Sc y O 3-δ (y represents a value of 0.2 to 0.8, δ represents a value of 0 to 3) represents the compound, or it can also be represented by the general formula: BaTi 1-y-x Sn y Sc x O 3-δ (y represents a value of 0.05 to 0.15, x represents a value of 0.2 to 0.8, and δ represents a value of 0 to 3) represents the compound.

[0043] The composition of the solid electrolyte and the aforementioned parent crystal in this specification can be determined by energy-dispersive X-ray diffraction (EDS) analysis. The sample exposed by grinding the surface of a dense solid electrolyte sintered in dry air to a depth of 100 μm or more with silicon carbide polishing paper is used. The sample is then irradiated with an electron beam accelerated to 15 kV, and the intensity of the characteristic X-rays produced is observed using a scanning electron microscope (SEM), thereby determining the composition of the solid electrolyte and the parent crystal. The ZAF method is used for quantification. It should be noted that scanning electron microscopes such as the Hitachi High-Tech Corporation "SU3500" (product name) or the Oxford Instruments "AZtecEnergy" (product name) can be used.

[0044] In the above solid electrolyte, the ionic radius of A is set as r. A Let r be the weighted average of the ionic radii of Ma and Mb based on the elemental presence ratio. M At that time, (r) M / r A The value of C can be between 0.24 and 0.54. The above C is expressed as C = 0.55 × r. A -0.89. By making (r M / r A When the value of C is within the above range, the lattice becomes softer, further reducing the proton diffusion barrier, and both the proton diffusion coefficient and proton conductivity are further improved. M / r A The lower limit of the value of ) + C can be, for example, 0.260 or higher, 0.300 or higher, 0.400 or higher, 0.430 or higher, 0.437 or higher, 0.440 or higher, or 0.443 or higher. If (r M / r AIf the lower limit of the value of C is within the above range, the lattice becomes more flexible, further reducing the proton diffusion barrier, and both the proton diffusion coefficient and proton conductivity are further improved. M / r A The upper limit of the value of ) + C can be, for example, below 0.500, below 0.480, below 0.460, below 0.458, or below 0.456. If (r M / r A If the lower limit of the value of C is within the above range, the lattice becomes more flexible, further reducing the proton diffusion barrier, and the proton diffusion coefficient and proton conductivity are further improved.

[0045] The lower limit of the lattice volume of the aforementioned solid electrolyte can be, for example, 70.678 × 10⁻⁶. -3 nm 3 Above, 71.965×10 -3 nm 3 Above, 72.490×10 -3 nm 3 Above, or 73.000×10 -3 nm 3 The above applies. If the lower limit of the lattice volume is within the above range, the lattice becomes more flexible, further reducing the proton diffusion barrier, and both the proton diffusion coefficient and proton conductivity are further improved. The upper limit of the lattice volume of the above solid electrolyte can, for example, be 85.052 × 10⁻⁶. -3 nm 3 Below, 83.000×10 -3 nm 3 Below, 80.000×10 -3 nm 3 Below, 78.000×10 -3 nm 3 Below, 75.000×10 -3 nm 3 Below, 73.665×10 -3 nm 3 Below, or 72.417×10 -3 nm 3 Below. If the upper limit of the lattice volume is within the above range, the lattice becomes more flexible, further reducing the proton diffusion barrier, and both the proton diffusion coefficient and proton conductivity are further improved. The lattice volume of the above solid electrolyte can be adjusted within the above range, for example, it can be 70.678 × 10⁻⁶. -3 nm 3 Above 85.052×10 -3 nm 3 Below, or 70.678×10 -3 nm 3Above 72.417×10 -3 nm 3 the following.

[0046] The aforementioned solid electrolyte exhibits excellent proton diffusion performance in the intermediate temperature range of 300–400°C. The lower limit of the proton conductivity of the aforementioned solid electrolyte in the 300–400°C range can be set, for example, to 1.0 × 10⁻⁶. -3 Scm -1 Above, 2.0×10 -3 Scm -1 Above, 3.0×10 -3 Scm -1 Above, or 10×10 -3 Scm -1 The above. There is no specific upper limit to the proton conductivity of the aforementioned solid electrolytes at 300–400°C; it is typically 30 × 10⁻⁶. -3 Scm -1 Below, or 20×10 -3 Scm -1 the following.

[0047] The proton conductivity in the intermediate temperature region described in this specification can be determined by AC impedance measurement. Specifically, it is determined according to the method described in the embodiments of this specification. It should be noted that the above-mentioned proton conductivity refers to the proton conductivity within the grain, that is, the proton conductivity in the bulk (σ). H.本体 )σ H.bulk (), expressed as the minimum value in the temperature range of 300-400℃.

[0048] The aforementioned solid electrolytes can be prepared through solid-phase synthesis or solution synthesis.

[0049] An example of a method for manufacturing a solid electrolyte includes: a step of pulverizing a mixture of raw materials containing a compound having A as a constituent element, a compound having Ma as a constituent element, and a compound having Mb as a constituent element to obtain a powder (pulverization step); a step of pressing the pulverized material to obtain a molded article (molding step); and a step of heat-treating the molded article at a temperature of 800 to 1700°C to obtain a sintered body (sintering step). The aforementioned A, Ma, and Mb refer to different elements, and the descriptions of A, Ma, and Mb as used in the above-described solid electrolyte method are applicable. Press molding may also include, for example, uniaxial press molding and cold isostatic pressing.

[0050] Compounds having A as a constituent element, compounds having Ma as a constituent element, and compounds having Mb as a constituent element can independently be oxides, nitrates, or carbonates. Examples of compounds having A as a constituent element include barium carbonate and barium nitrate. Examples of compounds having Ma as a constituent element include tin oxide and titanium oxide. Examples of compounds having Mb as a constituent element include scandium oxide and scandium nitrate.

[0051] The sintering process can also be carried out under atmospheric conditions. The heating temperature in the sintering process can be, for example, 1200–1700°C, 1400–1700°C, or 1600–1700°C. The heating rate in the sintering process can be, for example, 100–250°C / hour, 150–230°C / hour, or 180–200°C / hour.

[0052] The aforementioned solid electrolyte is useful, for example, as a component of fuel cells. Specifically, examples of such components include laminates in which the aforementioned solid electrolyte is disposed between electrodes. One embodiment of the laminate includes: a first electrode, an electrolyte membrane disposed on the first electrode, and a second electrode disposed on the electrolyte membrane on the side opposite to the first electrode. The electrolyte membrane contains the aforementioned solid electrolyte.

[0053] The first and second electrodes can be made from the same raw material or from different raw materials. When the above-mentioned laminate is a component of a fuel cell, for example, the first electrode can be the anode (fuel electrode) and the second electrode can be the cathode (air electrode).

[0054] The raw materials for the anode can be, for example, silver, platinum, palladium, nickel, a mixture of nickel and zirconium oxide, a mixture of nickel and cerium oxide, and a mixture of nickel and barium zirconate oxide.

[0055] The raw materials for the cathode can be, for example, silver, platinum, and perovskite oxides containing rare earth elements and 3d transition metals. Such perovskite oxides can be, for example, those derived from the general formula: D1 1-a D2 a B1 1-b B2 b O3 represents an oxide (0≤a≤1, 0≤b≤1). Here, D1 and D2 can be lanthanides (Ln) such as lanthanum (La), cerium (Ce), praseodymium (Pr), and samarium (Sm), or alkaline earth metals (AE) such as calcium (Ca), strontium (Sr), and barium (Ba). B1 and B2 can be manganese (Mn), iron (Fe), and cobalt (Co), etc. Specifically, as a raw material for the cathode, it can be Ln. 1-a AE a Mn 1-bFe b O3, Ln 1-a AE a Mn 1-b Co b O3 and Ln 1-a AE a Co 1- b Fe b O3, AE 1-a AE a Co 1-b Fe b O3, etc.

[0056] The thicknesses of the first and second electrodes can be adjusted according to the intended use of the laminate.

[0057] The thickness of the electrolyte membrane can be adjusted according to the required performance and application of the laminate. The upper limit of the electrolyte membrane thickness can be, for example, 500 μm or less, 400 μm or less, 300 μm or less, 150 μm or less, 50 μm or less, 25 μm or less, or 15 μm or less. By keeping the upper limit of the electrolyte membrane thickness within the above range, proton conductivity can be further improved. The lower limit of the electrolyte membrane thickness can be, for example, 0.1 μm or more, 0.5 μm or more, 1.0 μm or more, 3 μm or more, 5 μm or more, or 10 μm or more. By keeping the lower limit of the electrolyte membrane thickness within the above range, the reduction in the mechanical strength of the electrolyte membrane itself can be suppressed, and the insulation breakdown between electrodes can be more effectively suppressed. The thickness of the electrolyte membrane can be adjusted within the above range, for example, it can be 0.1–500 μm, 0.1–400 μm, 1.0–400 μm, 1.0–50 μm, or 5–15 μm.

[0058] The aforementioned laminate may also include other layers in addition to the first electrode, electrolyte membrane, and second electrode. Examples of these other layers include layers inserted between the first electrode and the electrolyte, and layers inserted between the second electrode and the electrolyte. Examples of layers inserted between the first electrode and the electrolyte include a mixture of nickel and barium zirconate oxides, a mixture of nickel and zirconium oxides, and a mixture of nickel and cerium oxides. Examples of layers inserted between the second electrode and the electrolyte include cerium oxides, barium zirconate oxides, cerium-added barium zirconate oxides, and barium cerate oxides.

[0059] Solid oxide fuel cells having the above-described laminated structure contain the aforementioned solid oxide as an electrolyte, thus allowing for a low operating temperature. The upper limit of the operating temperature of the solid oxide fuel cell can be set, for example, below 600°C, 550°C, 500°C, 450°C, 350°C, or 250°C. The lower limit of the operating temperature of the solid oxide fuel cell can be set, for example, above 100°C, 200°C, 230°C, or 300°C. The operating temperature of the solid oxide fuel cell can be adjusted within the above ranges, for example, from 250 to 600°C or from 100 to 590°C. Furthermore, because the solid oxide fuel cell having the above-described laminated structure contains the aforementioned solid oxide as an electrolyte, it can operate stably for extended periods (e.g., 200 hours or more).

[0060] The above description covers several embodiments, but this disclosure is not limited to any of these embodiments. Furthermore, the descriptions of the embodiments above are applicable to each other.

[0061] Example The present disclosure will now be described in further detail with reference to embodiments and comparative examples. However, the present disclosure is not limited to the embodiments described below.

[0062] [Screening of candidate parent crystals] Barium stannate (BaSnO3), barium titanate (BaTiO3), and barium zirconate (BaZrO3) were prepared. Powder X-ray diffraction was used to determine the cell volume and the number of perovskite units in the cell when a portion of the B-site atoms (Sn, Ti, and Zr) in the perovskite structure were replaced with scandium (Sc). The lattice volume was determined for each scandium addition ratio. Next, barium stannate (BaSnO3) with oxygen vacancies was prepared. 3-δ Barium titanate (BaTiO) 3-δ ) and barium zirconate (BaZrO) 3-δ Perform the same measurements. Present the results as follows: Figure 1 Additionally, the rate of change of the lattice volume corresponding to each figure is... and The values ​​are shown in Table 1.

[0063] [Table 1] (Example 1) [By Ba(Sn 0.3 Sc 0.7 O 3-δ [Preparation of barium stannate with added scandium] Barium carbonate (BaCO3, manufactured by Fujifilm and Koichi Chemicals Co., Ltd., purity: 99.9% by mass), tin oxide (SnO2, manufactured by High Purity Chemicals Co., Ltd., purity: 99.9% by mass), and scandium oxide (Sc2O3, manufactured by High Purity Chemicals Co., Ltd., purity: ≥99.9% by mass) were weighed into a container in a stoichiometric ratio to achieve the desired composition of barium stannate with added scandium (a composition in which y is 0.7). This mixture was then placed in a mortar with a specified amount of ethanol and wet-mixed. The mixture was heated to 1100°C at an atmospheric temperature at a heating rate of 300°C / hour and subjected to a heating treatment at 1100°C for 5 hours to obtain a pre-calcined powder.

[0064] The obtained pre-calcined powder was placed in a container, and a specified amount of ethanol and zirconium oxide balls were added. The mixture was then wet-milled for 3 days using a roller mill (NITTO KAGAKU CO.LTD.ANZ-52D) at a rotation speed of 300 rpm to obtain pulverized material. The pulverized material was then dried to obtain raw material powder.

[0065] The obtained raw material powder was shaped into granules with a diameter of 20 mm and a thickness of approximately 2 mm using a uniaxial pressure molding machine. These granules were then further pressurized at 250 MPa using cold isostatic pressing. The granules were heated to 1600°C while being fed with dry air at a flow rate of 100 mL / min, and then heat-treated at 1600°C for 12 hours to obtain a sintered body. To prevent barium from escaping from the system and disrupting the composition, a powder with the same composition as the raw material powder was prepared and used to coat the granules. The granules were then subjected to the same heat treatment. Through sintering, the diameter shrank to 13.5 mm, resulting in a sintered body with a density of 5.6 g / cm³. 3 The sintered body was obtained. X-ray diffraction (XRD) analysis confirmed that the sintered body possessed a single perovskite structure. Furthermore, energy-dispersive X-ray diffraction (EDS) analysis confirmed the presence of Ba(Sn) oxides in the sintered body. 0.3 Sc 0.7 O 3-δ It has a cationic composition.

[0066] (Example 2) [by Ba (Ti 0.2 Sc 0.8 O 3-δ [Preparation of barium titanate with added scandium] Titanium oxide (TiO2, manufactured by HIGH PURITY CHEMICALS, purity: 99.99% by mass) was used instead of tin oxide in Example 1. It was weighed in a manner consistent with the stoichiometric ratio of the target barium titanate with added scandium (a formula where y = 0.8). Otherwise, a pre-calcined powder was obtained in the same manner as in Example 1. The obtained pre-calcined powder was then placed in a container, and a specified amount of ethanol and zirconium oxide balls were added. The mixture was wet-milled for 1 hour using a planetary ball mill (FRITSCH, product name: Pulverisette 7 planetary ball mill) at a rotation speed of 300 rpm to obtain pulverized material. The pulverized material was dried to obtain raw material powder. The obtained raw material powder was shaped into granules with a diameter of 20 mm and a thickness of approximately 2 mm using a uniaxial pressure molding machine, and further pressurized at 250 MPa using cold isostatic pressing. The granules were heated to 1600°C while being fed into dry air at a flow rate of 100 mL / min, and then subjected to a heat treatment at 1600°C for 24 hours to obtain a sintered body. Similar to Example 1, the granules were subjected to the heat treatment with the powder coating them. Through sintering, the diameter shrank to 14.2 mm, resulting in a sintered body with a density of 5.0 g / cm³. 3 The sintered body was obtained. X-ray diffraction (XRD) analysis confirmed that the sintered body possessed a single perovskite structure. Furthermore, energy-dispersive X-ray diffraction (EDS) analysis confirmed the presence of Ba(Ti) in the sintered body. 0.2 Sc 0.8 O 3-δ It has a cationic composition.

[0067] (Example 3) [By Ba(Sn 0.15 Ti 0.05 Sc 0.8 O 3-δ [Preparation of barium tin titanate with added scandium] Barium carbonate (BaCO3, manufactured by Fujifilm and Koichi Pure Chemicals Co., Ltd., purity: 99.9% by mass), tin oxide (SnO2, manufactured by High Purity Chemicals Co., Ltd., purity: 99.9% by mass), titanium oxide (TiO2, manufactured by High Purity Chemicals Co., Ltd., purity: 99.99% by mass), and scandium oxide (Sc2O3, manufactured by High Purity Chemicals Co., Ltd., purity: 99.9% by mass or higher) were weighed into a container in a stoichiometric ratio that conforms to the composition formula (general formula in which y is 0.8) of barium tin titanate with scandium added as targeted. Otherwise, a pre-calcined powder was obtained in the same manner as in Example 1. Then, the obtained pre-calcined powder was placed in a container, and a specified amount of ethanol and zirconium oxide balls were added. The mixture was then wet-milled for 3 hours using a planetary ball mill (FRITSCH, product name: Pulverisette 7 planetary ball mill) at a rotation speed of 300 rpm to obtain pulverized material. The pulverized material was then placed in a container, and a specified amount of ethanol and zirconium oxide balls were added. The mixture was then wet-milled for 3 days using a roller mill (NITTO KAGAKU CO.LTD. ANZ-52D) at a rotation speed of 300 rpm to obtain pulverized material. The pulverized material was dried to obtain raw material powder. The raw material powder was then shaped into granules with a diameter of 15 mm and a thickness of approximately 2 mm using a single-shaft pressure molding machine. Further, cold isostatic pressing was applied at 300 MPa. The granules were heated to 1600°C while being fed with dry air at a flow rate of 100 mL / min, and then heat-treated at 1600°C for 12 hours to obtain a sintered body. Similar to Example 1, the granules were heat-treated with the powder coated on them. X-ray diffraction (XRD) analysis confirmed a single perovskite structure. Furthermore, energy dispersive X-ray spectroscopy (EDS) analysis confirmed the presence of Ba(Sn) oxides in the sintered body. 0.15 Ti 0.05 Sc 0.8 O 3-δ It has a cationic composition.

[0068] (Comparative Example 1) [By Ba(Zr 0.4 Sc 0.6） O 3-δ [Preparation of barium zirconate with added scandium] Barium nitrate (manufactured by Fujifilm and Koko Pure Chemicals Co., Ltd., Ba(NO3)2, purity: 99.9% by mass), zirconium oxynitrate dihydrate (manufactured by Kanto Chemical Co., Ltd., ZrO(NO3)2·2H2O), and scandium nitrate n hydrate (High Purity Chemical Research Institute, Co., Ltd., Sc(NO3)3·nH2O, purity: 3N) were weighed into a container in stoichiometric proportions to achieve the desired composition of barium zirconate with added scandium (a composition in which x is 0.6). The solutions were then dissolved in approximately 800 mL of distilled water to prepare an aqueous solution. It should be noted that the amount of hydrate was adjusted based on the confirmation of the hydration content through thermogravimetric analysis.

[0069] Ethylenediaminetetraacetic acid (manufactured by Fujifilm and Kazumitsu Chemical Co., Ltd., EDTA, purity: 99.0% by mass) and citric acid (manufactured by Fujifilm and Kazumitsu Chemical Co., Ltd., purity: 99.0% by mass) were added to the above aqueous solution in an amount of 0.5 moles each, based on the total moles of metal ions in the aqueous solution. The pH of the reaction solution was adjusted to between 9.0 and 10 using an ammonia solution to dissolve the added reagents, thus obtaining a reaction solution. Next, the reaction solution was heated on a stirrer for approximately 300 minutes to allow the contents to react and remove the solvent from the system. The surface temperature of the stirrer was adjusted to 180°C. The resulting gel was then heated in a microwave oven to remove the solvent contained in the gel, yielding a solid.

[0070] The solid obtained as described above was placed in a heating furnace and heated from room temperature at a rate of 5°C / min until it reached 900°C, then calcined for 10 hours to obtain the precursor. The precursor was placed in a container, and a specified amount of ethanol and zirconium oxide balls were added. The mixture was then wet-milled using a planetary ball mill (FRITSCH, product name: Pulverisette 7 planetary ball mill) at a rotation speed of 300 rpm for 2 hours to obtain a pulverized material. The pulverized material was then dried. At the end of the milling process, X-ray diffraction confirmed that it had become a mixture of scandium-added barium zirconate, scandium-added zirconium oxide, and barium carbonate.

[0071] The above-mentioned pulverized mixture was shaped into granules with a diameter of 20 mm and a thickness of approximately 2 mm using a uniaxial pressure molding machine. These granules were then further pressurized at 300 MPa using cold isostatic pressing. The granules were then heated at 1600°C for 24 hours while being fed with dry air at a flow rate of 100 mL / min to obtain a sintered body. Through sintering, the diameter shrank to 15 mm, resulting in a sintered body with a density of 5.3 g / cm³. 3The sintered body was obtained. X-ray diffraction (XRD) analysis confirmed that the sintered body possessed a single perovskite structure. Furthermore, energy-dispersive X-ray diffraction (EDS) analysis confirmed the presence of BaZr. 0.4 Sc 0.6 O 3-δ It has a cationic composition.

[0072] [Proton conductivity of solid electrolytes (σ)] H.本体 )σ H.bulk [Measurement] For the solid electrolytes prepared in Examples 1, 2 and Comparative Example 1, the proton conductivity (σ) in the bulk at approximately 300°C was measured by electrochemical impedance spectroscopy. H.本体 ) to be measured.

[0073] Specifically, firstly, both sides of the sintered body were ground to a thickness of approximately 500 μm. Then, a silver layer with a thickness of 650 nm was deposited on both sides of the ground sintered body using a DC sputtering apparatus (manufactured by Sanyu Electron Co., Ltd., product name: SC-701HMC II), which was used as the test sample.

[0074] A current collector consisting of a silver mesh (manufactured by Nilaco Corporation) and a gold wire with a diameter of 0.1 mm was prepared. A silver paste (manufactured by Tanaka Precious Metals Industry Co., Ltd., product name: TR-3025) was applied to the current collector, and the current collector was then bonded to the two polished surfaces of the test sample. The paste was dried in a dryer at 55°C. The resulting laminate was then heated to approximately 800°C for 1 hour in a dry argon atmosphere to obtain the test sample. The test sample was connected to an electrochemical detector cell with a controllable atmosphere via the gold wire. The test sample was heated to approximately 720°C in a dry argon atmosphere, and simultaneously, the atmosphere was switched to an argon atmosphere with a water vapor pressure of 0.02 atm. Then, while decreasing the temperature, the temperature was controlled by alternating current impedance spectroscopy within a temperature range of approximately 600°C to 30°C at a rate of 0.1 to 10. 6 The proton conductivity was determined by scanning at a frequency of Hz. Measurements at various temperatures were performed as follows: AC impedance measurements were continuously conducted until the resistance value stabilized sufficiently and no longer changed. Based on the measurement results, the proton conductivity (σ) in the bulk at 300℃ was determined. H.本体 ). Figure 3 The diagram shows the individual parent crystals. / The relationship with proton conductivity. Additionally... Figure 4 The temperature dependence of proton conductivity for the solid electrolyte of Example 1 is shown in the figure for reference.

[0075] [Determination of proton concentration] The proton concentration of the solid electrolytes prepared in Examples 1-3 and Comparative Example 1 was determined by thermogravimetric analysis. Specifically, the sintered body used in the proton conductivity measurement was pulverized in an agate mortar to obtain a powder. The obtained powder was heated at 1000°C for 1 hour in a dry argon atmosphere using a thermogravimetric analyzer (NETZSCH, product name: STA449F3 Jupiter). The atmosphere surrounding the powder was humidified with water vapor, and the concentration was determined by the water vapor partial pressure (p). H2O The temperature was adjusted to 0.02 atm to introduce protons into each solid oxide. A humidified atmosphere was then switched on, and the temperature was maintained until equilibrium was reached and no further mass change occurred. Assuming that oxygen vacancies in each solid oxide were hydrated via water molecules, the proton introduction rate was calculated based on the observed mass increase during the above operation.

[0076] Next, by progressively decreasing the temperature of the sintered body to approximately 115°C, the temperature dependence of the proton induction rate was obtained. As the temperature decreased progressively, the proton induction rate increased, and the proton induction rate for each solid oxide around approximately 300°C, i.e., the general formula: AMa, was determined. 1-y Mb y O 3-δ H z The value of z in the equation. For example, regarding the solid oxide of Example 3, Ba(Sn) 0.15 Ti 0.05 Sc 0.8 O 3-δ H z The value of z in the equation is set to 0.70. Figure 8 The results for the solid oxides of Examples 2 and 3 are shown in (a) for reference.

[0077] [Determination of the proton diffusion coefficient of solid electrolytes and determination of the activation energy of proton diffusion] The proton diffusion coefficient and activation energy of proton diffusion were determined for the solid electrolytes prepared in Examples 1-3 and Comparative Example 1. Specifically, the proton diffusion coefficient was determined by dividing the obtained proton conductivity by the proton concentration according to the Nernst-Einstein relation. The activation energy of proton diffusion was determined by the slope obtained by plotting the proton diffusion coefficient against the reciprocal of temperature, according to the definition of the Arrhenius diagram. Figure 2 The results for the solid oxides of Examples 1, 2 and Comparative Example 1 are shown in the figure. Figure 2 (a) is a graph showing the results of the proton diffusion coefficient measurement. Figure 2(b) is a graph showing the results of the determination of the activation energy for proton diffusion.

[0078] [Evaluation of the chemical stability of solid electrolytes] The chemical stability of the solid electrolyte prepared in Example 1 was evaluated. Specifically, the proton conductivity was measured for 258 hours while switching between heavy water (D₂O) and light water (H₂O) for the water vapor supplied to the sample. The measurement conditions were: water vapor pressure: 0.02 atm; temperature: 301°C. It should be noted that the proton conductivity when supplied with heavy water was 5.61 × 10⁻⁶. -3 Scm -1 The proton conductivity when supplied with light water is 10.60 × 10⁻⁶. -3 Scm -1 The results will be shown in Figure 5 .

[0079] like Figure 5 As shown, the solid electrolyte prepared in Example 1 maintained its proton conductivity for at least 258 hours, confirming that the obtained solid electrolyte has excellent chemical stability.

[0080] [Proton diffusion coefficient (D) in the bulk of solid electrolytes] H.本体 [Evaluation] The proton diffusion coefficient in barium stannate with added scandium, as determined by AC impedance spectroscopy, was evaluated for the solid electrolyte prepared in Example 1.

[0081] Specifically, based on D H.本体 =(σ H.本体 RT) / (F 2 C H It is calculated using the Nernst-Einstein relation, where R is the gas constant, T is the temperature, F is the Faraday constant, and C is the temperature. H Let be the proton concentration. Substitute the proton conductivity and proton concentration at each temperature to calculate the proton diffusion coefficient. Figure 6 The figure shows the Arrennis plot of the obtained proton diffusion coefficient. Figure 6 The results of barium zirconate with scandium and barium zirconate with yttrium are shown together for comparison.

[0082] [Evaluation as a solid electrolyte for fuel cells] The solid electrolyte prepared in Example 1 was evaluated as a solid electrolyte for use in fuel cells.

[0083] Specifically, firstly, the 15mm diameter granular sintered body (solid electrolyte) prepared in Example 1 was ground on both sides with a granule thickness of 0.3mm (300μm). After grinding, a platinum paste (manufactured by Tanaka Precious Metals Industry Co., Ltd., trade name: TR-7907) was applied to the two ground surfaces of the granules in a circular shape with a diameter of 8mm. The mixture was then calcined at 700°C for 2 hours in a dry air atmosphere. Next, it was cooled to 100°C for 100 hours in a humid atmosphere with a relative humidity of 2%RH to form a platinum electrode. Furthermore, a platinum mesh was placed on the platinum electrode formed in the above manner, and a silver paste (manufactured by Tanaka Precious Metals Industry Co., Ltd., trade name: TR-3205) was applied. After drying the silver paste, 60μL of 2 mol% cerium nitrate was dropped onto both electrodes, and the mixture was calcined at 300°C for 2 hours in a humid atmosphere with a relative humidity of 2%RH. After firing, the electrode surfaces turn black due to the influence of cerium nitrate. One electrode corresponds to the anode, and the other to the cathode. Next, platinum wire is wound around the side of the granules as a reference electrode. In this way, an evaluation sample is prepared.

[0084] like Figure 7 As shown in (a), a circuit with an evaluation sample was prepared and installed. Furthermore, the relationship between battery voltage and power density and current density was measured. Additionally, the change in proton conductivity after 100 hours of continuous operation was confirmed. The results are presented below. Figure 7 . Figure 7 (b) is a graph showing the relationship between battery voltage and power density and current density. Figure 7 (c) is a graph showing the time dependence of proton conductivity under fuel cell operating conditions. This result confirms that the solid electrolyte prepared in Example 1 can exhibit the theoretical open-circuit electromotive force corresponding to the gas atmosphere on both the cathode and anode sides. Furthermore, it was confirmed that stable fuel cell operation can be achieved continuously for 100 hours.

[0085] [By Ba(Sn 0.15 Ti 0.05 Sc 0.8 O 3-δ The proton diffusion coefficient (D) in barium stantanite with added scandium is represented by the bulk. H.本体 ) and proton conductivity (σ H.本体 [Determination of] For the solid oxide prepared in Example 3, the proton diffusion coefficient (D) in the bulk was measured. H.本体 ) and proton conductivity (σ H.本体 The determination of ) was performed under the same conditions as for the solid oxide of Example 1. The results are shown in Figure 8 (b) and (c). Figure 8Both (b) and (c) describe the preparation of Ba(Ti) in Example 2. 0.2 Sc 0.8 O 3-δ The results are shown for the determination of barium titanate with added scandium. For example... Figure 8 As shown in (c), the structure of Ba(Sn) is confirmed. 0.15 Ti 0.05 Sc 0.8 O 3-δ The indicated value is barium tin titanate with added scandium, which has a proton conductivity greater than 10 × 10⁻⁶ at 300 °C. -3 Scm -1 It is excellent.

[0086] Industrial availability According to this disclosure, a solid electrolyte can be provided that exhibits excellent proton diffusion performance in the intermediate temperature range of 300–400°C. Furthermore, according to this disclosure, a fuel cell can be provided that operates excellently in the intermediate temperature range.

Claims

1. A solid electrolyte having a perovskite-type crystal structure, wherein the solid electrolyte has the following characteristics: (General formula: AMaO) 3-δ (In the general formula, A represents the A-site element in the perovskite structure, Ma represents the B-site element in the perovskite structure, and δ is a value less than 3) represents the parent crystal, and the element Mb in which a portion of Ma in the parent crystal is replaced by solid solution. in, The parent crystal is | | / | Crystals with a value greater than 0 and less than 1.568, To demonstrate how Mb can be dissolved in AMaO 3-δ The slope in the graph representing the relationship between the change in lattice volume and the Mb substitution solution ratio in perovskite crystals. The slope in the graph shows the relationship between the change in lattice volume and the substitutional solid solution ratio of Mb when Mb is dissolved in a crystal represented by AMaO3, which is obtained by filling the δ-space of the perovskite crystal with oxygen atoms.

2. The solid electrolyte as described in claim 1, wherein, Let the ionic radius of A be r. A Let r be the weighted average of the ionic radii of Ma and Mb based on the elemental presence ratio. M At that time, (r) M / r A The value of ) + C is 0.24 to 0.54, where C is C = 0.55 × r A -0.89 represents the value.

3. The solid electrolyte as described in claim 1 or 2, wherein its lattice volume is 70.678 × 10⁻⁶. -3 nm 3 Above 85.052×10 -3 nm 3 the following.

4. The solid electrolyte as described in claim 1 or 2, wherein its proton conductivity is 1.0 × 10⁻⁶. -3 Scm -1 above.

5. The solid electrolyte as described in claim 1 or 2, wherein, The A is selected from at least one of the following groups: Ba, Sr, Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Li, Na, K, Rb, Cs, and Mg. Ma and Mb are each selected from at least one of the following groups: Ti, Zr, Hf, Sn, Pb, Bi, Si, Ge, Ga, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y, Lu, In, Sc, V, Nb, Ta, Cr, Mo, W, Sb, Mg, Al, As, and Re.

6. The solid electrolyte as described in claim 1 or 2, wherein it is composed of the general formula: BaSn 1-y Sc y O 3-δ (y represents values ​​from 0.2 to 0.7, δ represents values ​​from 0.2 to 3), General formula: BaTi 1-y Sc y O 3-δ (y represents values ​​from 0.2 to 0.8, δ represents values ​​from 0 to 3), or general formula: BaTi 1-y-x Sn y Sc x O 3-δ (y represents a value of 0.05 to 0.15, x represents a value of 0.2 to 0.8, and δ represents a value of 0 to 3) represents.

7. A laminate comprising a first electrode, an electrolyte membrane disposed on the first electrode, and a second electrode disposed on the electrolyte membrane on the side opposite to the first electrode side. The electrolyte membrane comprises the solid electrolyte as described in claim 1 or 2.

8. A fuel cell comprising the laminate of claim 7.

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