JP6041606B2 - Proton conductive material, solid electrolyte membrane, and method for producing proton conductive material - Google Patents

Description

  The present invention relates to a proton conductive material, a solid electrolyte membrane, and a method for producing a proton conductive material.

Energy / environmental problems are the biggest technological issues that human beings should solve in the first half of the 21st century. Currently, about 80% of the primary energy sources used by humans on earth are hydrocarbon fossil fuels such as oil, coal, and natural gas. The chemical energy possessed by fossil fuels is released as heat through a combustion reaction that occurs with oxygen in the air. For this reason, the use of fossil fuels is inevitably accompanied by the release of carbon dioxide (CO ₂ ), which is a greenhouse gas. Currently, the main cause of climate change over the entire globe is thought to be warming caused by the greenhouse effect due to increased emissions of CO _{2 and the} like. Therefore, the development of technology for using energy sources that do not emit CO ₂ (so-called clean energy, green energy, or renewable energy) is regarded as an urgent issue.

Biomass is a carbohydrate produced by plants using sunlight as energy source and CO ₂ in the atmosphere and H ₂ O in the ground. Therefore, it is an energy source in which solar energy is condensed, like so-called fossil fuels. However, in the case of biomass, the CO ₂ produced by the combustion of the biomass is absorbed from the current atmosphere, so the CO ₂ concentration in the atmosphere is not increased. This feature is expressed as carbon neutral. Therefore, biomass is classified as renewable energy.

  Biomass is roughly classified into cereals (starch) and sugars, and celluloses that form trees and stems. The former is converted to ethanol by fermentation technology, and the latter is converted to methanol by a partial oxidation steam reforming method or the like. Cellulosic biomass has not been effectively used yet and is often discarded by incineration or the like. Therefore, the development of technology using methanol that will be produced in the future is one of the most important issues in energy and environmental issues.

  Methods for extracting energy from hydrocarbon fuels including methanol include a method using heat generated by a combustion reaction such as an internal combustion engine and a simple combustion method, and a direct power generation technique using a fuel cell. In the former method using combustion heat, the maximum energy efficiency is limited as a Carnot engine. In the latter fuel cell, the maximum power energy that can be extracted is equal to the change in free energy of reaction. For this reason, the fuel cell has a principle advantage as a highly efficient energy conversion device.

As explained in paragraphs 0003 and 0004, the most effective energy source for CO ₂ reduction is biomass-derived methanol. Methanol has an excellent feature as a fuel for fuel cells. Methanol, which is C1 alcohol, can be directly supplied to the fuel cell fuel chamber together with water without passing through the steam reformer. In particular, a room temperature operation device using a solid polymer electrolyte in the fuel cell body is called DMFC (direct methanol fuel cell).

  However, DMFC has a major drawback of low power generation efficiency. The first cause is a phenomenon called methanol crossover. The second cause of the low power generation efficiency of DMFC is that the platinum-based catalyst is poisoned by CO adsorption, resulting in a large anode overvoltage. In order to solve this problem, active research has been conducted on the type, amount, and loading method of the catalyst, but no effective technology has been developed yet (Non-patent Document 1).

  Methanol crossover in DMFC can be prevented by solidifying the proton conductor. In addition, it is believed that CO adsorption can be suppressed by operating at a temperature of at least 150 ° C, preferably 300 ° C or higher. Therefore, the development of solid electrolytes with significant proton conductivity in the middle temperature range is key to improving the power generation efficiency of DMFC fuel cells.

  As mentioned above, solid electrolytes exhibiting significant proton conductivity in the middle temperature range are being actively developed, but phosphate glasses with the highest proton conductivity among oxide glasses are currently being developed. Is attracting attention.

In order to achieve significant proton conductivity, a high hydrogen concentration is a necessary condition. Therefore, in Patent Document 1, a Ca, Sr, Ba, Zn, Al, Si, Pb, Mg, or B phosphate glass containing P ₂ O ₅ at a high concentration (50 to 80 mol%) is selected and used. A technique is disclosed that dissolves for a short time at a temperature of 900 ° C. or less, and leaves moisture derived from raw materials and atmosphere in glass at a high concentration. However, in this method, it is difficult to obtain a product of a certain quality because the glass forming reaction that proceeds in the melt state is forcibly terminated in the middle of the equilibrium, and in order to achieve high proton conductivity. It is impossible to achieve a high proton concentration that is an indispensable condition.

In Patent Document 2, Ba, Ca, Al, or Zn phosphate glass containing a high concentration of P ₂ O ₅ is crystallized in an atmosphere containing water vapor at a temperature of 250 ° C. to less than 400 ° C. Is disclosed. The proton conductivity of this material is attributed to the OH groups incorporated as a result of hydrolysis of both the crystal and the glass matrix by moisture in the atmosphere when crystals are precipitated by heat treatment. The conductivity of the material made by this technology is shown as 6 × 10 ^-2 S / cm at 300 ° C.

Further, Non-Patent Document 2 and Patent Document 3 describe the temperature dependence of proton conductivity of SnP ₂ O ₇ pyrophosphate crystals in which about 10% of 4A group elements such as Sn are substituted with 3A group elements such as In, and The power density characteristics of a fuel cell prototyped using this are shown. Regarding conductivity, the highest value of 2 × 10 ⁻² S / cm at 250 ° C. is shown, and it is shown that it decreases at higher temperatures. It has been reported that the power density of a fuel cell fabricated using a 0.35 mm thick solid electrolyte reaches 260 mW / cm ² at 250 ° C.

JP2003-192380 JP2007-265803 JP 2008-53224 A

Japan Patent Office 2006 Patent Application Technology Trend Research Report Fuel Cell (Summary) Electrochem, Solid State Lett. 9 A105-A109 (2006) 47th Ceramics Science Symposium Proceedings, “Medium Temperature Proton Conductivity and Thermal Stability of Phosphate-rich Ultraphosphate”, Takuro Kaneko, Satoru Fujitsu, Hiroshi Kawai January 8, 2009, Osaka J. Mater. Sci. Lett. 9 244-245 (1990)

  The inventors paid attention to the technology using the above phosphate glass and studied phosphoric acid glass. The prior art described in paragraphs 0011 and 0012 deposited amorphous polyphosphoric acid at the grain boundaries. It has been clarified that high conductivity is realized by making it (Non-Patent Document 3). Since amorphous polyphosphoric acid is an unstable substance, the techniques disclosed in Patent Document 2 and Patent Document 3 are not practical because they lack long-term stability. Furthermore, these technologies are considered to have a limit in improving the conductivity because the region for realizing the proton conductivity is localized at the grain boundary.

  It is an object of the present invention to provide a proton conductive material, a solid electrolyte membrane, and a method for producing a proton conductive material that stably have high proton conductivity in the middle temperature range.

The first feature of the present invention is that a glass material containing an alkali oxide, an oxide of a polyvalent positive element having a plurality of oxidation number states, and a phosphorus oxide is derived from the alkali oxide. Nonporous proton conductivity obtained by substituting at least a part of alkali ions with protons, and having a proton conductivity of 0.005 S / cm or more in at least a part of a temperature range of 250 ° C. to 500 ° C. Materials (except for proton conductors that are AlPO4 ion-exchange mesopore porous bodies having AlPO4 as a main component and pores having a pore diameter of 2 nm or more) .

Also, preferably, at least a portion of the range of the temperature of 250 ° C. or higher 450 ° C. or less, it proton conductivity 0.005 S / cm or more.

  The proton conductivity is 0.01 S / cm or more in at least a part of the temperature range of 250 ° C. or more and 500 ° C. or less. Preferably, the proton conductivity is 0.005 S / cm or more in at least a part of the temperature range from 250 ° C. to 450 ° C.

  Preferably, the glass material contains the alkali oxide in a cation molar percentage of 5% to 40%.

  Preferably, the glass material contains 3% or more and 45% or less of the oxide of the polyvalent positive element in terms of cation mole percentage. Preferably, the glass material contains 10% or more and 45% or less of the oxide of the polyvalent positive element in terms of cation mole percentage.

Preferably, the proton concentration is 5 × 10 ²⁰ atoms / cm ³ or more and 1.5 × 10 ²² atoms / cm ³ or less in terms of OH.

Preferably, the alkali oxide is at least one selected from the group consisting of lithium oxide (LiO _1/2 ), sodium oxide (NaO _1/2 ), and potassium oxide (KO _1/2 ).

  Preferably, the polyvalent positive element is at least one selected from the group consisting of iron (Fe), tungsten (W), and germanium (Ge).

Preferably, the glass material includes titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), tantalum oxide (TaO _5/2 ), niobium oxide (NbO _5/2 ), and molybdenum oxide (MoO _3). And at least one selected from any of the above.

Preferably, the glass material further includes at least one selected from either a divalent metal oxide (RO) or a trivalent metal oxide (TO _3/2 ).

The second feature of the present invention is that a glass material comprising an alkali oxide, an oxide of a polyvalent positive element having a plurality of oxidation number states, and a phosphorus oxide is derived from the alkali oxide. obtained by replacing at least a portion of the alkali ions in the proton, at least part of the range of the temperature of 250 ° C. or higher 500 ° C. or less, the proton conductivity of 0.005 S / cm or more, the proton conductive material (except And a non-porous solid electrolyte membrane including a proton conductor which is an AlPO4 ion-exchange mesopore porous body having AlPO4 as a main component and having a pore diameter of 2 nm or more .

  A third feature of the present invention is that a glass material containing an alkali oxide, an oxide of a polyvalent positive element having a plurality of oxidation number states, and a phosphorus oxide is contained under application of an electric field. In the method for producing a proton conductive material, at least a part of the alkali ions derived from the alkali oxide is substituted with protons in a hydrogen atmosphere and at a temperature of 250 ° C. or higher.

  Preferably, a direct-current potential difference is applied such that the electric field is 5 V / cm or more and the voltage is 3 V or more, and at least a part of the alkali ions derived from the alkali oxide is substituted with protons.

  Preferably, of the pair of electrodes for applying an electric field to the glass material, the positive electrode is a metal material that dissolves hydrogen, and the negative electrode is made of a metal material that dissolves alkali atoms, a carbon material, and a transition metal oxide material. It is at least one selected from the group.

  According to the present invention, it is possible to provide a proton conductive material, a solid electrolyte membrane, and a method for producing a proton conductive material that have a stable and high proton conductivity in an intermediate temperature range.

It is a flowchart which manufactures the proton-conductive material concerning one Embodiment of this invention. It is a figure which shows the composition of the proton conductive material concerning Example 1, and its evaluation result. It is a figure which shows the composition of the proton conductive material concerning Example 1, and a comparative example, and its evaluation result. It is a figure which shows the composition of the proton conductive material concerning Example 2, 3, and its evaluation result. It is a figure which shows the EPMA measurement result about sample W10-1. It is a figure which shows the conductivity measurement result of a W type | system | group sample with a numerical value. It is a figure which shows the conductivity measurement result of a W type | system | group sample with a numerical value. It is the figure which graphed the conductivity measurement result of the W5 type sample. It is the figure which graphed the conductivity measurement result of the W10 type | system | group sample. It is the figure which graphed the conductivity measurement result of the W25 type | system | group sample. It is the figure which graphed the conductivity measurement result of the W40 type | system | group sample. It is the schematic of the hydrogen concentration battery used in order to measure a transport number. It is a figure which shows the measurement result of the density cell electromotive force of a W type | system | group sample. It is a figure which shows the conductivity measurement result of F type | system | group sample by a numerical value. It is the figure which graphed the conductivity measurement result of F system sample. It is a figure which shows the measurement result of the density cell electromotive force of F type | system | group sample. It is a figure which shows the conductivity measurement result of G type | system | group sample and GW type | mold sample numerically. It is the figure which graphed the conductivity measurement result of the G type sample. It is the figure which graphed the conductivity measurement result of the GW type sample. It is a figure which shows the measurement result of the density cell electromotive force of G system sample and GW system sample.

  First, an outline of the present invention will be described.

Although there is no strict definition regarding “medium temperature” in the fuel cell-related technology, the term “medium temperature” is used herein to mean a temperature of about 250 ° C. to 550 ° C. for convenience.
In fuel cells using materials with high proton conductivity at medium temperatures, the system has been simplified by eliminating the need for fuel reformers (depending on the operating temperature and fuel type) and the ability to use metallic materials for battery components. Thus, cost reduction and high reliability are realized. In addition, the steady operation at the medium temperature enables the power generation efficiency to be improved and the high-temperature exhaust heat to be effectively used, thereby improving the total energy efficiency.

Phosphate glass materials that are thermochemically and mechanically stable at intermediate temperatures are made by melting methods well known to those skilled in the art. However, in this production method, since a dehydration reaction generally proceeds in a melting process that requires a temperature higher than the middle temperature range, it is impossible to produce a glass material having a high proton concentration.
The inventors of the present invention devised a unique technique for stably producing a solid electrolyte material having high proton conductivity in the middle temperature range. This is a method of replacing alkali ions in a glass material produced by a melting method with protons. This is named “AP replacement method”.

As the glass treatment, for example, a plate glass containing sodium (Na) ions is immersed in a molten potassium nitrate (KNO ₃ ) solution, and a portion of Na ions in the glass surface layer is replaced with K ions, and a compressive stress layer is formed on the surface. A technology that improves the surface strength through chemical formation-chemical strengthening method or ion exchange strengthening method-can be considered. However, a similar method cannot be used as a means for replacing alkali ions with protons. This is because there is no proton bath (proton source) that is stable in the middle temperature range, and most of the alkali ions in the glass material cannot be replaced with protons. That is, the AP replacement method is based on a completely independent principle.

The principle of the AP replacement method will be described below.
First, focus on the operating temperature and atmospheric conditions of the medium temperature fuel cell. The surface on the anode side of the solid electrolyte is exposed to an atmosphere containing hydrogen with a partial pressure on the order of several percent to several tens of percent regardless of the type of fuel, while the surface on the oxidizer side is exposed to oxygen, water vapor, and optionally nitrogen. It is exposed to the atmosphere that contains it. During power generation, a steady proton flow is generated from the fuel electrode toward the oxidant electrode in the electrolyte layer. That is, in developing a new electrolyte material, it is necessary to create a material that can stably hold a high concentration of protons under such conditions.

The steps of the AP replacement method will be described. First, an alkali oxide having a concentration within a range of several percent to several tens percent (hereinafter, may be abbreviated as “AO _1/2 ”), and an oxide of a polyvalent positive element having a plurality of oxidation number states ( Hereinafter, it may be abbreviated as “MO _{p / 2} ”, where M represents a polyvalent positive element, and P represents its oxidation number). Process. Here, M means a positive element that can be controlled to a high oxidation number state when the atmosphere for producing the material is air or oxygen. Depending on the desired material properties, TiO ₂ , ZrO ₂ , TaO _5/2 , NbO _5/2, MoO _3, etc. with a constant oxidation number or oxide (RO) of divalent metal (R) or 3 An oxide of valence metal (T) (TO _3/2 ) may be further added.
Next, electrodes are applied to the two opposing surfaces of the material. The positive electrode material may be any metal material (hydrogen-dissolving permeable metal material) that decomposes and dissolves hydrogen in the gas phase. For example, a Pd thin film can be used. The negative electrode material may be any material as long as it dissolves alkali atoms. For example, a molten Sn metal or a plate-like carbon material can be used.

  Next, the process proceeds to a step of replacing alkali ions in the material with protons. This is a substitution of a monovalent cation such as an alkali ion with a proton using electrolysis in a solid state realized for the first time by the present invention. This step is performed under the above-mentioned assumed operating temperature of the fuel cell, that is, in an intermediate temperature range and in an atmosphere containing low-pressure hydrogen, while applying an appropriate DC voltage between the two electrodes. For example, it is appropriate that the applied voltage is 3 V or more and the electric field strength is 5 V / cm or more, but a higher electric field may be used as long as discharge does not occur.

  In the said process, the oxidation-reduction reaction represented by the following formula | equation (1)-(4) advances.

(Positive electrode) H ₂ → 2H → 2H ⁺ + 2e ⁻ (1)

  That is, hydrogen decomposition and oxidation reaction in the gas phase. Protons generated here are dissolved in the glass, and electrons are supplied to the external circuit and transported to the negative electrode. Proton dissolution proceeds in the bulk glass by the following reaction.

(In glass) 2H ⁺ +2 (A ⁺ / ⁻ OPO ⁻ / M ^{p +} )
^{→ 2 (H + / - OPO} - / M p +) + 2A + (2)

^{Here, (A + / - OPO -} / M p +) is a solution at alkaline ions dissolved in the glass expressed schematically. That is, it is a partial structure indicating that the ^{Mp +} ion and the A ⁺ ion are dissolved while compensating for the negatively charged phosphate skeleton. Formula (2) shows that the alkali ions dissolved in the glass were replaced by protons introduced from the gas phase and released. Free alkali ions are accelerated in the glass by an electric field and transported to the vicinity of the negative electrode.

(Negative electrode) 2 A ⁺ 2 e ⁻ + C _n → C _n A ₂ (3)

In the negative electrode, as shown in the formula (3), the reduction reaction of alkali ions proceeds and the neutral atom (A) is generated. Here, C _n represents a graphite electrode used as a negative electrode material. At this time, if a material that dissolves A and has metallic conductivity is used as the negative electrode material, alkali atoms are extracted and removed from the glass into the negative electrode material. As the negative electrode material, any material having these functions can be used. For example, Sn, Pb, Ag, and other metal materials, and carbon and transition metal oxides used as positive electrode materials for lithium ion batteries, etc. Can be used. From the viewpoint of replacing more alkali ions with protons, the negative electrode material preferably has a capacity capable of dissolving the entire amount of alkali ions discharged from the glass material.

  The total reaction according to the formulas (1) to (3) is as shown in the following formula (4).

(Total ^{_{reaction) H 2 + 2 (A +}} / - OPO - / M p +) + C n
^{→ 2 (H + / - OPO} - / M p +) + C n A 2 (4)

  That is, decomposition oxidation of hydrogen in the gas phase at the positive electrode and reduction extraction of alkali ions at the negative electrode. In this process, alkali ions in the glass are replaced by protons. As a result of the replacement, the glass material is generally distorted, but since this process is performed at a temperature slightly lower than the glass transition point of the material, a necessary distortion removal process immediately after the AP replacement is completed, for example, By adding annealing, a material having the required mechanical strength can be obtained.

The oxidation of hydrogen in the gas phase represented by the formulas (1) and (2) and the dissolution in the glass are caused by the presence of the oxide MO _{p / 2} component of a polyvalent metal having a plurality of oxidation number states. Make it significant. The M ^{p +} ion in the glass material is a component having a function of dissolving the generated proton in the glass by causing a redox reaction with hydrogen even under no electric field.
That is, as shown in Formula (5), MO _{p / 2} is a component that promotes proton dissolution by forming a redox pair of H ⁺ / M ^{(p−1) +} .

H ₂ + 2 (A ⁺ / ⁻ OPO ⁻ / M ^{p +} )
^{→ 2 (A + / - OPO} - / H + / M (p-1) +) (5)

  As described above, a glass material that can contain a high concentration of hydrogen oxide under medium temperature conditions is an alkali oxide at a concentration that is at least equal to the concentration of the target hydrogen oxide and a polyvalent positive that takes multiple oxidation number states. A method in which a phosphate glass material containing an oxide of an element is produced in the previous step, and then AP substitution is performed by replacing the alkali ions with protons by heat treatment in a direct current electric field / hydrogen-containing atmosphere as a subsequent step. Is significantly manufactured by.

In the AP substitution method, it is preferable to use any of LiO _1/2 , NaO _1/2 , and KO _1/2, or a mixture of these in any proportion as the alkali component. The concentration of the alkali component is preferably 5% to 40% in terms of cation mole percentage. If the concentration of the alkali component is less than 5%, the conductivity stays on the order of 10 ⁻⁴ and does not reach the target value, and the required level of conductivity cannot be obtained. In a situation where the alkali oxide is not contained or the concentration thereof is low, the ion migration is insufficient and the proton cannot be effectively substituted. On the other hand, if it exceeds 40%, the mechanical properties, chemical properties, and thermal properties of the material are insufficient, and a material that can be put to practical use cannot be obtained.
Further, AgO _1/2 , CuO _1/2 , TlO _1/2, etc., which are known to work as movable ions under an electric field in an oxide glass, may be used.

In addition, the ion ^{Mp +} of the polyvalent positive element having a plurality of oxidation number states, which is a constituent of the glass material before and after the AP substitution, can oxidize and dissolve hydrogen in the gas phase by reducing itself. Any one of Fe ³⁺ , W ⁶⁺ and Ge ⁴⁺ or a mixture thereof is preferable.
Since these ions are also components that promote the movement of protons that are responsible for conductivity, it is desirable that the concentration be high as long as glass formation and the required stability, thermochemical function, etc. are not impaired. Accordingly, the cation mole percentage is preferably 3% or more and 45% or less, and more preferably 10% or more and 45% or less. In the situation where the multivalent positive element ion M ^{p +} does not exist or its concentration is low, substitution of alkali ions with protons only occurs at a low concentration and in the vicinity of the surface layer (about 0.01 mm).

Moreover, in order to achieve the target proton conductivity, it is necessary to form a stable phosphate glass. For this reason, the concentration of the PO _5/2 component is preferably 25% to 60% in terms of cation mole percentage.

The second governing factor that determines the proton conductivity of the material is proton mobility. Although the microscopic mechanism of the proton transfer process is not clear, it has been clarified that TiO ₂ , ZrO ₂ , TaO _5/2 , NbO _5/2 and MoO ₃ have a function of increasing this.
It is desirable that the concentration be high as long as the glass formation and the required stability, thermochemical function, etc. are not impaired. Therefore, the total content of TiO ₂ , ZrO ₂ , TaO _5/2 , NbO _5/2 and / or MoO ₃ is preferably 25% or less in terms of cation mole percentage.

The proton conductive material may be used as a material constituting various electrochemical devices such as a fuel cell. Therefore, it is preferable to satisfy requirements related to physical properties such as mechanical properties, chemical stability, and thermal properties in accordance with applications in addition to proton conductivity. In order to improve and improve these properties, the inclusion of the RO component and / or the TO _3/2 component is effective in improving the properties. Considering the decrease in proton conductivity, the total content of these is preferably 20% or less in terms of cation mole percentage.

Moreover, a hydrogen-dissolving permeable metal material is used for the positive electrode as the electrode applied to the glass molded body in the AP replacement step. Specifically, Ti, Cr, Co, Ni, Mo, Rh, Pd, Ag, Sn, Sb, Nb, Ta, W, Ir, Os, Pt, Au, Pb and Bi, or a mixture thereof Materials selected from the system are preferred.
For the negative electrode, a metal material that dissolves alkali atoms, a carbon material, a transition metal oxide material, or a material selected from a mixed system thereof is preferable. As the negative electrode material, those having excellent electron conductivity are more preferable. In the AP replacement step, alkali ions contained in the glass molded body are discharged in an atomic state. Therefore, it is more preferable that the negative electrode material has a capacity capable of dissolving it.

  Further, the AP replacement step can be effectively realized by using electrolysis in a solid state and electric field oxidation-reduction phenomenon. For example, it is preferable to perform heat treatment in an atmosphere containing hydrogen and at a temperature of 250 ° C. or higher while applying a DC voltage having a voltage of 3 V or higher and an electric field of 5 V / cm or higher between the positive electrode and the negative electrode. From the viewpoint of the use environment and stability of the material, it is preferably 250 ° C. or higher. Specifically, when used as a fuel cell electrolyte, the condition is assumed to be 250 ° C. or higher, and desirably 300 ° C. or higher.

From the viewpoint of proton conductivity in the middle temperature range, in the proton conductive material, the concentration of HO _1/2 introduced by AP substitution is preferably 2.5% or more and 40% or less. Protons are preferably contained at a concentration of 5 × 10 ²⁰ atoms / cm ³ or more and 1.5 × 10 ²² atoms / cm ³ in terms of OH.

Next, a process for producing a proton conductive material will be described.
In addition, this invention is limited to these description and is not interpreted.

Proton-conducting materials have AO _1/2 and MO _{p / 2} with concentrations on the order of several percent to ten percent respectively (depending on the target composition, TiO ₂ , ZrO ₂ , TaO _5/2 , NbO _5/2 and (Or MoO ₃ , RO and / or TO _3/2 ) and a step of producing a phosphate glass molded body, and at least a part (for example, half or more) of alkali ions in the obtained phosphate glass molded body And a step of substituting with protons.
FIG. 1 shows a flow chart (S10) for producing a proton conductive material according to this embodiment.

In step 102 (S102), a phosphate glass molding is produced.
The step of producing the phosphate glass molded body is performed by a well-known method. That is, carbonates for the AO _1/2 component, oxides for the MO _{p / 2} component, oxides for the TiO ₂ , ZrO ₂ , TaO _5/2 , NbO _5/2 and / or MoO ₃ components, A batch is made using carbonate or oxide for the RO component, oxide for the TO _3/2 component, and regular phosphoric acid for the PO _5/2 component, and this is made into a high alumina crucible or platinum. Transfer to a crucible and melt in an electric furnace. The melting atmosphere may be air. In order to maintain the positive element (M) that can take a plurality of oxidation state in a high oxidation state, dry oxygen may be used. The homogeneous melt is transferred to a carbon mold and annealed to remove strain. The obtained bulk glass material is cut and polished, and formed into a desired shape.

In step 104 (S104), an electrode is applied to the phosphate glass molded into a plate shape.
Electrodes are applied to the two opposing surfaces of the phosphate glass formed into a plate shape. As the positive electrode material, a metal material capable of decomposing and dissolving hydrogen molecules, such as Pd, is used. A Pd thin film is deposited by sputtering, for example. The film thickness is, for example, 100 nm or less.

  As the negative electrode material, a material having a solvent function with respect to alkali is used. Since the AP replacement step is performed in a forming gas atmosphere containing, for example, about 5% hydrogen, the importance of oxidation resistance is suppressed. For example, a graphite-based carbon material used as an electrode material for a Li battery can be applied and used. Also, a high-density liquid metal such as lead or tin can be used. The capacity | capacitance of negative electrode material shall have a magnitude | size which can melt | dissolve the whole quantity of the alkali discharged | emitted from a glass molding. Lead wires are drawn from both electrodes.

In step 106 (S106), AP replacement is performed.
The plate-like glass material provided with the electrode is set in an atmosphere control electric furnace. For example, 5% H ₂ -95% N ₂ forming gas is circulated in the furnace. The heating temperature is a temperature in the range of “transition point −50 ° C.” from the transition point of the target glass material. In this embodiment, the temperature is generally between 350 ° C and 550 ° C. After the furnace temperature is controlled to the target temperature, a voltage is applied between the positive electrode and the negative electrode using a DC power source. The voltage is preferably 3 V or more, and the electric field is preferably 5 V / cm or more, more preferably 10 V / cm to 40 V / cm. In order to semi-quantitatively evaluate the amount of substituted alkali, an ammeter is connected in series with the glass material and the output is monitored.

  Thus, a proton conductive material is produced by substituting at least a part of the alkali ions derived from the alkali oxide with protons in the glass material under application of an electric field.

  In order to evaluate the characteristics of the produced proton conductive material (glass material after AP substitution), the amount of proton introduced, the proton conduction conductivity and its temperature dependence, and the transport number are measured.

[Amount of proton introduced (OH concentration C _OH evaluation)]
Since the introduced proton exists in the form of OH, the amount of OH is evaluated. The OH concentration is evaluated by measuring infrared absorption, and the profiles along the thickness direction of the OH concentration and alkali (in the case of Na) are evaluated by measuring microscopic infrared absorption and EPMA intensity, respectively.

[Conductivity of proton conduction and its temperature dependence (conductivity evaluation)]
This evaluation can be performed by the AC impedance method. The Pd thin film electrode used for AP substitution can be used as it is as an electrode for conductivity measurement. The carbon-based electrode used for the negative electrode is mechanically removed, and then a Pd thin film is deposited. Since Pd works as a non-blocking electrode in an atmosphere containing hydrogen, evaluation using direct current is also possible. This material is set in an atmosphere-controlled electric furnace. The measurement atmosphere is 5% H ₂ -95% N ₂ forming gas. The measurement temperature ranges from room temperature to 550 ° C.

[Transportation Rate (Transportation Rate Evaluation)]
When an electrochemical device is configured using a proton conductive material as a solid electrolyte containing the proton conductive material, the proton transport number is an important characteristic along with the conductivity. The transport number can be obtained from the electromotive force of a hydrogen concentration cell that uses a proton conductive material.

  At the stage of determining the AP replacement conditions (positive electrode / negative electrode material, applied electric field size, replacement operation temperature / time, etc.), the positive and negative electrodes are removed from the sample after AP replacement. Specifically, the concentration of introduced OH is evaluated by measurement of infrared absorption, and the profiles along the thickness direction of the material of OH concentration and alkali (in the case of Na) are microscopic infrared absorption and EPMA (Electron Probe Micro Analyzer) Evaluate by measuring strength.

Next, Examples 1 to 3 will be described.
2 to 4 show the composition of the produced proton conductive material, the OH concentration C _OH in the material after AP substitution, the activation energy (ΔE), and the proton conductivity of the material after AP substitution of 10 ⁻² S. Indicates minimum temperature (Tc) above / cm.

(Example using phosphate glass containing W)
As an Example produced using the phosphate glass containing W, five types of samples W5-1 to 5-5 in FIG. 2 and thirteen types of samples W10-1 to W40-3 in FIG. Species (hereinafter may be collectively referred to as “W-based samples”). As a comparative example, Sample W25-7 having an alkali oxide concentration of less than 5% is also shown.

[Glass material production]
As raw material chemicals in the production of glass materials subjected to AP substitution treatment, Li ₂ CO ₃ , Na ₂ CO ₃ , NaPO ₃ , H ₃ PO ₄ , WO ₃ , BaO, La ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Ta ₂ O ₅ and Nb ₂ O ₅ were used. Each raw material is weighed and mixed to achieve the target composition, held at 700 ° C for 1 hour, then heated to a target temperature of 1200 ° C to 1400 ° C at 10 ° C per minute, and held for 3 hours after reaching the target temperature. did. A platinum crucible was used for melting. The atmosphere was air. The melt was poured into a cylindrical carbon mold having a diameter of 20 mm, transferred to an annealing furnace, and strain was removed.

[AP replacement]
The AP replacement process will be described. Each of the 18 types of materials of Sample W5-1 to Sample W40-3 is a thin plate material that is assumed to be used in an electrochemical device such as a fuel cell from the annealed bulk glass (hereinafter referred to as “device material”). And a material having a shape suitable for various evaluations in the development stage (hereinafter referred to as “evaluation material”).
Regarding the device material, a glass disk having a thickness of about 0.4 mm and a diameter of 20 mm was cut out, and two surfaces thereof were polished to a thickness of 0.2 mm or less. The evaluation material was a plate-like material having a thickness after polishing of about 2 mm.

A Pd thin film was deposited on one surface of these plate-like glass materials (apparatus material and evaluation material) by the sputtering method (hereinafter referred to as “a surface”). A graphite thick film was applied to the other facing surface (hereinafter referred to as “b surface”). A platinum lead wire was pulled out from each electrode, and the produced “Pd thin film electrode / glass material plate / graphite thick film electrode” laminate was set in a gas flow type electric furnace. This was heated under the flow of a forming gas with a hydrogen concentration of 5.0% and with a DC voltage applied. The heating temperature was set to 400 ° C. to 600 ° C. depending on the composition. This heating temperature is preferably in the range of the glass transition point Tg to Tg-50 ° C. of each glass material. When the heating temperature is in the vicinity of the glass transition point Tg of the glass material, ions contained in the glass material move more effectively.
The applied voltage between both sides of the ab was such that the electric field was 40 V / cm. Biasing was performed so that the a-plane on the Pd electrode side was positive and the b-plane on the graphite electrode side was negative. An ammeter was installed to monitor the total charge flowing in the material during AP replacement treatment. The processing time was determined as follows. That is, as shown in the above-described formulas (1) to (4), the current flowing in the glass material is generated when all alkali ions in the glass material are replaced by protons and discharged to the graphite electrode. Therefore, the time for the total number of charges carried by the current to be equal to the total number of alkalis contained in the glass material was observed, and the processing time was three times as long.
The material after the heat treatment was gradually cooled under gas flow.

[OH concentration C _OH evaluation]
The device material after AP replacement was evaluated for the total OH concentration.
Regarding the graphite electrode on the b-side, this was mechanically removed in a wet state of the organic solvent. Further, the Pd thin film deposited on the surface a was removed by buffing. Regarding the thin plate material after the electrode was removed, the absorption spectrum in the 4000 cm ⁻¹ to 1500 cm ⁻¹ region was measured with an FT-IR apparatus (Shimadzu 8200PC). When the absorbance of the plate-like material having a thickness of 0.2 mm was too large, the plate was thinned so that the absorption spectrum could be measured. Based on the absorbance difference A before and after AP substitution measured in the wave number range of 3200 cm ^{−1 to} 3300 cm ⁻¹ , the OH concentration C _OH (pieces / cm ³ ) in the material was evaluated based on the following equation (6).

_{C OH = 2 · A · N} A / 1000 d ε (6)

N _A is Avogadro's number, d is the thickness (cm) of the material glass plate, and ε is the molar extinction coefficient as H ₂ O, which is obtained by the following equation (7) (Non-patent Document 4).

ε = 110 · L · mol ⁻¹ cm ⁻¹ (7)

As shown in FIGS. 2 and 3, the hydrogen concentration (OH concentration C _OH ) in 18 kinds of materials of Sample W5-1 to Sample W40-3 is almost proportional to the concentration of alkali in the glass material before AP replacement. You can see that The absolute concentration is 1.5 × 10 ²¹ pieces / cm ³ , which is 5 × 10 ²⁰ pieces / cm ³ or more even in the case of the sample W25-5 having the lowest alkali concentration, and the sample has a high alkali concentration. It can be seen that W5-1 to Sample W5-5, Sample W10-1 and Sample W10-3 have reached the order of 10 ²² pieces / cm ³ . As an effect of the type of alkali on the OH concentration, Li tends to increase in concentration compared to Na.
The hydrogen concentration of Sample W25-7, which is a comparative example, was on the order of 10 ²⁰ pieces / cm ³ .

[Replacement confirmation evaluation]
Next, an experiment conducted to confirm that Na is replaced by hydrogen will be described.
FIG. 5 shows the results of a point analysis of the sample W10-1 for the Na concentration before and after AP substitution using EPMA from the positive electrode side (a surface) to the negative electrode side (b surface). Moreover, the measurement result of OH density | concentration after AP substitution is also shown about sample W10-1. The concentration value is converted into a value calculated from the density and composition of the glass so that it can be easily compared with the hydrogen concentration.

As shown in FIG. 5, the value before replacement does not vary greatly throughout the thickness direction of the glass, and is about 1.2 × 10 ²² pieces / cm ³ . The density after replacement is about 1.5 × 10 ²⁰ cells / cm ³ , and is reduced by about two orders of magnitude by the replacement process. The concentration profile after replacement is also flat throughout the thickness direction.

Hydrogen intrusion dissolution is a diffusion-controlled reaction. Regarding the flatness of the OH concentration at each position from the surface in the depth direction, a strip of slice was cut out from the evaluation material of about 2 mm thickness, and the profile of the OH concentration at each site from the surface a to the surface b Was evaluated using microscopic IR. The OH concentration after AP substitution is about 1 × 10 ²² pieces / cm ³ , which almost corresponds to the decrease in Na.
That is, it was confirmed that the alkali ions in the glass material were uniformly substituted with protons by the AP substitution method.

[Conductivity evaluation]
The conductivity of the device material subjected to the AP replacement treatment was measured by the AC impedance method.
The a-plane electrode was used as it was without removing the Pd thin film deposited during the AP replacement treatment. Regarding the b-plane, the graphite electrode in which the alkali was dissolved was mechanically removed in a wet state of the organic solvent, and then a Pd thin film was deposited to form an electrode. Since Pd also functions as a non-blocking electrode in an atmosphere containing hydrogen, evaluation using direct current is possible. A plate-like material with a Pd thin film was set in a conductivity measuring device, and the conductivity was measured by the AC method. An impedance analyzer (Solartron SI 1260) was used for the measurement. The measurement frequency was between 8 MHz and 10 MHz. The impedance measurement results were plotted on a complex plane, and the intersection of the semicircle with the real axis on the low frequency side was defined as the resistance value R (Ω) of the sample. The measurement was performed while sequentially raising the temperature from the lowest possible temperature to 400 ° C. After maintaining the target temperature for 10 minutes, the conductivity was measured. The atmosphere was forming gas or nitrogen.

6 and 7 show the results of measuring the conductivity of the W-based sample in numerical values, and FIGS. 8 to 11 are graphs showing the results of measuring the conductivity of the W-based sample.
All 18 types of Sample W5-1 to Sample W40-3 showed thermal activation type temperature dependence over a high temperature range of 400 ° C. As shown in FIGS. 2 and 3, the activation energy is 38 kJ / mole or less for Sample W5-1, Sample W5-2, Sample W5-3, Sample W10-1, and Sample W10-3 with high proton concentrations. As a solid proton conductive material, the value is extremely low. Even in the sample W25-5 having a relatively low proton concentration compared with other samples, it is 66 kJ / mole, which is a low value as a solid material containing no molecular water.

When considering fuel cell applications, it is desirable that the proton conductivity of the solid electrolyte membrane is 10 ⁻² S / cm or more. As shown in FIGS. 2 and 3, the minimum temperature Tc at which the proton conductivity of each W-based sample after AP substitution is 10 ⁻² S / cm or more is included in the range of 230 ° C. to 320 ° C. It is shown that high and sustained power generation efficiency can be obtained when operating at a temperature not lower than this temperature and not higher than 400 ° C. Such temperature dependence is evidence that the proton conductive material has high thermal stability. In the sample W25-7 as a comparative example, the proton conductivity reaches 10 ⁻² S / cm. There wasn't.

As shown in FIGS. 6 to 11, all 18 types of W-based samples show activated proton conductivity. Samples W5-1 to W5-5 show proton conductivity of about 4 × 10 ⁻³ S / cm or higher at a temperature of 200 ° C. or higher, and about 1 × 10 ⁻² S at a temperature of 450 ° C. or higher. The proton conductivity was not less than / cm, and the proton conductivity was not less than about 0.1 S / cm at a temperature of not less than 500 ° C. This high conductivity characteristic is maintained even at temperatures of 500 ° C. or higher. Thus, it is clear that TiO ₂ , NbO _5/2 , ZrO ₂ and TaO _5/2 have the effect of further enhancing the high temperature stability of the hydrogen-containing glass material after AP substitution.
Sample W10-1, Sample W10-2, Sample W10-3, Sample W25-1, Sample 25-6, and Sample 40-1 have proton conductivity of 5 × 10 ^{−3 in} the range of 250 ° C. to 400 ° C. S / cm or more.
In addition, Sample W10-1, Sample W10-2, Sample W10-3, Sample W25-2, Sample W25-3, Sample W25-6, and Sample W40-1 are proton conducting in the range of 300 ° C. to 400 ° C. The rate was 10 ⁻² S / cm or higher, and Sample W10-1 and Sample W10-3 had proton conductivity of 10 ⁻² S / cm or higher in the range of 250 ° C. or higher and 400 ° C. or lower.
When the sample W25-1 and the sample W35-1 were compared, the conductivity was further improved in the sample W25-1 containing NbO _5/2 .
Sample W25-7, which is a comparative example, has a conductivity that is about two orders of magnitude smaller than Sample W10-1 to Sample W40-3.

[Transportation evaluation]
Next, the measurement result of the transportation number will be described.

First, the configuration of the hydrogen concentration battery used for measuring the transport number will be described.
FIG. 12 is a schematic diagram of the hydrogen concentration battery 10 used for measuring the transport number. The hydrogen concentration battery 10 is configured to be installed so that the sample 12 is sandwiched between the high pressure chamber 14 and the low pressure chamber 16. Hydrogen is introduced into each of the high pressure chamber 14 and the low pressure chamber 16, and the pressure of the introduced hydrogen is higher in the high pressure chamber 14 than in the low pressure chamber 16. At this time, as the sample 12, a Pd thin film deposited on both surfaces of the produced proton conductive material (glass material plate after AP substitution) is used.
The high-pressure chamber 14 is formed inside the ceramic tube 20, and the ceramic tube 20 is provided with an introduction tube 22 for introducing a gas and an exhaust port 24 for exhausting the gas. The ceramic tube 20 and the sample 12 are in contact with the sample through an Ag ring seal 26. When the Ag ring seal 26 is pressurized, the airtightness of the high-pressure chamber 14 is ensured. The lead wire 28 is pulled out from the Ag ring seal 26.
The low pressure chamber 16 has the same configuration as the high pressure chamber 14.

  Using the results measured using the hydrogen concentration cell described above, the transport number was evaluated by the following equation (8).

V = ti (RT / 2F) ln ( _PH2 , R / _PH2 , M) (8)

Where V is the electromotive force, R is the gas constant, T is the battery temperature, F is the Faraday constant, PH2 and R are the hydrogen partial pressure in the high hydrogen partial pressure chamber, and PH2 and M are the hydrogen content in the low hydrogen partial pressure chamber. Pressure, ti is the proton transport number. From the equation (8), when the actually measured electromotive force V is plotted against log (P _H2 , R / P _H2 , M), ti can be evaluated from the gradient.

  FIG. 13 shows the electromotive force when a hydrogen concentration cell is configured using Sample W5-1, Sample W10-3, Sample W25-3, and Sample W40-2. The measurement temperature was 450 ° C, 375 ° C, 400 ° C and 350 ° C for each sample. From the slopes of these plots, it can be seen that the proton transport number is 0.98 to 0.99. That is, it was confirmed that substantially all current carriers are protons. This is also a result of the fact that substantially all of the alkali ions in the precursor glass are replaced with protons.

(Example using phosphate glass containing Fe)
As shown in FIG. 4, as an example produced using phosphate glass containing Fe, there are cases where four types of samples F10-1 to F20-2 (hereinafter referred to as “F-based samples”) are collectively referred to. ) Is applicable.

[Glass material production]
Li ₂ CO ₃ , Na ₂ CO ₃ , Fe ₂ O ₃ , and H ₃ PO ₄ were used as raw material chemicals in the production of a glass material subjected to AP substitution treatment. Each raw material was weighed and mixed to achieve the target composition, held at 700 ° C for 1 h, then heated to 1200 ° C to 1400 ° C at a target temperature of 10 ° C per minute depending on the composition, and after reaching 3 h Retained. A high alumina crucible was used for melting. The atmosphere was air. The melt was poured into a cylindrical carbon mold having a diameter of 20 mm, transferred to an annealing furnace, and strain was removed.

[AP replacement]
AP replacement treatment and evaluation were performed according to the procedure described above in Example 1. In Example 2, the other surface facing the Pd electrode was brought into contact with a metal tin shot piece.

  A Pd thin film was deposited on one surface of the sheet glass material by the sputtering method (surface a). A platinum lead wire was pulled out from the Pd electrode, a quartz glass crucible was set in a gas introduction type vertical electric furnace, and a metal tin shot piece was added thereto. The W wire lead was drawn out from the metal tin layer, and then the produced “Pd thin film electrode / glass material plate” laminate was disposed so that the b-plane was in contact with the metal tin layer. The metal tin layer functions as an electrode on the b-plane. This is heated under the flow of a forming gas having a hydrogen concentration of 5.0% and with a DC voltage applied. In the heating process, the metallic tin is a liquid electrode and constitutes a good contact state with the b-plane. Hereinafter, operations related to the AP replacement process are the same as those in the first embodiment.

[OH concentration C _OH evaluation]
The device material after AP replacement was evaluated for the total OH concentration.
The Pd thin film deposited on the a surface and the metal tin residue on the b surface were removed by buffing. Regarding the thin plate material after the electrode was removed, the absorption spectrum in the 4000 cm ⁻¹ to 1500 cm ⁻¹ region was measured with an FT-IR apparatus (Shimadzu 8200PC). The details of the measurement are the same as in the case of Example 1 described above.

As shown in FIG. 4, it can be seen that the hydrogen concentration in the four materials of Sample F10-1 to Sample F20-2 is substantially proportional to the alkali concentration in the glass material before AP replacement. Further, the absolute concentration is 2.7 × 10 ²¹ pieces / cm ³ which is 5 × 10 ²⁰ pieces / cm ³ or more even in the case of the sample F30-1 material having the lowest alkali concentration. In Example 2, the influence of the type of alkali on the OH concentration is not clearly seen.

[Conductivity evaluation]
FIG. 14 shows the conductivity measurement result of the F-based sample in numerical values, and FIG. 15 is a graph of the conductivity measurement result of the F-based sample.
The four materials of Sample F10-1 to Sample F20-2 all showed thermal activation type temperature dependence up to a high temperature range of 450 ° C. As shown in FIG. 4, the activation energy is 76.9 kJ / mole in the sample F10-1 having a high proton concentration, which is higher than that in the W-based sample of Example 1. In sample F30-1, which has a relatively low proton concentration compared to other materials, it was 108.6 kJ / mole.

  As shown in FIG. 4, the Tc of each F-system sample is included in the range of 354 ° C. to 390 ° C. When operated at a temperature higher than this temperature and lower than 450 ° C., high and sustained power generation efficiency can be obtained. It is shown that.

As shown in FIGS. 14 and 15, Sample F10-1, Sample F20-1, and Sample F20-2 have proton conductivity of 5 × 10 ⁻³ S / cm or more in the range of 350 ° C. to 450 ° C. became.
Each F-based sample had a proton conductivity of 10 ⁻² S / cm or more in the range of 400 ° C. to 450 ° C.

[Transportation evaluation]
The transportation number was evaluated by the same method as in Example 1 described above.
In FIG. 16, the electromotive force at the time of comprising a concentration cell using sample F10-1, sample F20-2, and sample F30-1 is shown. The measurement temperature was 350 ° C., 400 ° C., and 450 ° C. for each sample. From the slopes of these plots, it can be seen that the proton transport number is 0.98 or more. That is, it was confirmed that substantially all current carriers are protons. In the AP replacement treatment of this example, molten metal tin was used as the negative electrode material, but it can be seen that even in this case, substantially all of the alkali was discharged.

(Example using phosphate glass containing Ge)
As shown in FIG. 4, as an example produced using a phosphate glass containing Ge, there are cases in which four types of samples Ge10-1 to Ge20-2 (hereinafter referred to as “G-based samples”) are collectively referred to. ), And four types of sample GW30-1 to sample GW40-2 (hereinafter may be collectively referred to as “GW-based sample”), a total of eight types.

[Glass material production]
Li ₂ CO ₃ , Na ₂ CO ₃ , Nb ₂ O ₅ , GeO ₂ , WO ₃ , and H ₃ PO ₄ were used as raw material chemicals in the production of a glass material subjected to AP substitution treatment. Each raw material was weighed and mixed to achieve the target composition, held at 700 ° C for 1 h, then heated to a target temperature of 1200 ° C to 1450 ° C at 10 ° C per minute, depending on the composition, and reached for 3 h Retained. A platinum crucible was used for melting. The atmosphere was air. The melt was poured into a cylindrical carbon mold having a diameter of 20 mm, transferred to an annealing furnace, and strain was removed.

[AP replacement]
AP replacement treatment and evaluation were performed according to the procedure described above in Example 1.

[OH concentration C _OH evaluation]
The device material after AP replacement was evaluated for the total OH concentration.
As shown in FIG. 4, it can be seen that the hydrogen concentration in the eight materials of Sample G10-1 to Sample GW40-2 is substantially proportional to the alkali concentration in the glass material before AP replacement. When the G-type sample and the GW-type sample are compared, the latter OH concentration tends to be slightly high. The absolute concentration is about 5.5 × 10 ²¹ pieces / cm ³ which is one digit larger than 5 × 10 ²⁰ pieces / cm ^{3 in} the case of the sample G30-1 and sample GW50-1 materials having the lowest alkali concentration. Yes. In Example 3, the influence of the type of alkali on the OH concentration is not clearly seen.

[Conductivity evaluation]
FIG. 17 shows numerical results of the conductivity measurement results of the G-based sample and the GW-based sample.
FIG. 18 is a graph showing the conductivity measurement result of the G-based sample, and FIG. 19 is a graph showing the conductivity measurement result of the GW-based sample.
The G-type sample was up to 350 ° C., and the GW-type sample was up to 400 ° C., all showing thermal activation type temperature dependence. As shown in FIG. 4, the activation energy was observed to be a relatively high value of 84 kJ / mole to 104 kL / mole in the G-based sample. In addition, those of the GW samples were observed to be lower than those of the W sample of Example 1, 38.5 kJ / mole to 58.6 kJ / mole.

  As shown in FIG. 4, Tc of the G-based material is included in the range of 270 ° C. to 290 ° C., and those of the GW-based sample are distributed between 260 ° C. and 300 ° C. In the former, because of the large activation energy, a very high conductivity of 0.1 S / cm at 350 ° C. has been realized. Therefore, when a fuel cell using a G-based material is operated at 300 ° C. to 350 ° C., very high power generation efficiency is realized. For GW-based samples, a relatively wider temperature range, between 250 ° C and 400 ° C, is a suitable operating temperature range.

As shown in FIGS. 17-19, sample G10-1 is in the range of 250 ° C. or higher and 350 ° C. or lower, and GW30-1, GW40-1 and GW40-2 are in the range of 250 ° C. or higher and 450 ° C. or lower. Each proton conductivity was 5 × 10 ⁻³ S / cm or more.
Each G-based sample had a proton conductivity of 10 ⁻² S / cm or more in the range of 300 ° C. to 350 ° C. and each GW-based sample in the range of 300 ° C. to 400 ° C.

[Transportation evaluation]
The transportation number was evaluated by the same method as in Example 1 described above.
FIG. 20 shows an electromotive force when a concentration cell is configured using the sample G20-1 and the sample GW40-2. The measurement temperatures are 350 ° C., 350 ° C. and 400 ° C. for each sample. From the slopes of these plots, it can be seen that the proton transport number is 0.97 or more. That is, it was confirmed that substantially all current carriers are protons.

  It can be said that the key to the practical application of fuel cells in the near future is the success or failure of the development of proton conductive solid electrolyte materials that operate in the middle temperature range. The biggest challenge in the development of this material is what kind, form, and structure of the material that can stably maintain a high concentration of protons in the middle temperature range, which is an essential condition for realizing high proton conductivity. There is a problem of how it can be produced. The proton conductive material and the manufacturing method thereof according to the present invention provide a significant answer to this problem for the first time.

  The proton conductive material according to the present invention stably exhibits high proton conductivity at a temperature in the middle temperature range. This proton conductive material is subjected to post-processing and processing required by its application, and includes various types of medium temperature fuel cells. It is used as a solid electrolyte member of a simple electrochemical device.

10 Hydrogen concentration cell 12 Sample 14 High-pressure chamber 16 Low-pressure chamber 20 Ceramic tube 22 Introduction tube 24 Exhaust port 26 Ring seal

Claims (13)

In a glass material containing an alkali oxide, an oxide of a polyvalent positive element having a plurality of oxidation number states, and a phosphorus oxide, at least a part of alkali ions derived from the alkali oxide is substituted with protons. A non-porous proton conductive material having a proton conductivity of 0.005 S / cm or more in a temperature range of 250 ° C. or higher and 500 ° C. or lower (provided that AlPO ₄ is the main component, Except for a proton conductor which is an AlPO ₄ ion-exchange mesopore porous body having pores with a pore diameter of 2 nm or more). In at least some range of temperatures 250 ° C. or higher 500 ° C. or less, proton conductive material according to claim 1, wherein the proton conductivity of 0.01 S / cm or more. The glass material is a proton conducting material according to any one of claims 1 to 2 comprising the alkali oxides a 5% to 40% by Kachionmoru percentage. The proton conductive material according to any one of claims 1 to 3 , wherein the glass material contains an oxide of the polyvalent positive element in a cation molar percentage of 3% to 45%. 5 × 10 ²⁰ pieces concentration protons in OH terms / cm ³ or more 1.5 × 10 ²² / cm ³ or less proton conductor material according to any claims 1 to 4. The alkali metal oxide is at least one selected from the group consisting of lithium oxide (LiO _1/2 ), sodium oxide (NaO _1/2 ), and potassium oxide (KO _1/2 ). 5. The proton conductive material according to any one of 5 . The polyvalent positive elements, iron (Fe), tungsten (W), and proton conductive material according to any one of claims 1 to 6 is at least one selected from the group consisting of germanium (Ge). The glass material is any of titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), tantalum oxide (TaO _5/2 ), niobium oxide (NbO _5/2 ), and molybdenum oxide (MoO ₃ ). proton conductor material according to any one of claims 1 to 7 further comprising at least one selected from or. The proton conductivity according to any one of claims 1 to 8 , wherein the glass material further contains at least one selected from either a divalent metal oxide (RO) or a trivalent metal oxide (TO _3/2 ). material. In a glass material containing an alkali oxide, an oxide of a polyvalent positive element having a plurality of oxidation number states, and a phosphorus oxide, at least a part of alkali ions derived from the alkali oxide is substituted with protons. Proton conductive material having a proton conductivity of 0.005 S / cm or more in a temperature range of 250 ° C. or more and 500 ° C. or less (provided that AlPO ₄ is the main component and the pore diameter is 2 nm or more). A non-porous solid electrolyte membrane including a proton conductor which is an AlPO ₄ ion-exchange mesopore porous body having pores).   A glass material containing an alkali oxide, an oxide of a polyvalent positive element having a plurality of oxidation number states, and a phosphorus oxide, under application of an electric field, in a hydrogen-containing atmosphere, and at a temperature of 250 ° C. or higher. A method for producing a proton conductive material, wherein at least a part of alkali ions derived from the alkali oxide is substituted with protons. The production of a proton-conductive material according to claim 11 , wherein a direct-current potential difference is applied with an electric field of 5 V / cm or more and a voltage of 3 V or more to substitute at least a part of the alkali ions derived from the alkali oxide with protons. Method. Of the pair of electrodes for applying an electric field to the glass material,
The positive electrode is a metal material that dissolves hydrogen,
The method for producing a proton conductive material according to claim 11 or 12 , wherein the negative electrode is at least one selected from the group consisting of a metal material that dissolves alkali atoms, a carbon material, and a transition metal oxide material.

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