JP5273654B2 - Novel proton conductor and method for producing the same - Google Patents

Description

The present invention relates to a method for producing a proton conductor for an electrochemical energy conversion device used in a large-capacity capacitor or a fuel cell, and relates to a large-capacity capacitor and a fuel cell using the same as a solid electrolyte.

A fuel cell is a system that generates electricity by a chemical reaction between hydrogen and oxygen. Since the reaction product is only water in principle, there is great expectation as an energy source with a small load on the global environment. The development of a practical technology for fuel cells has become an urgent social demand against the background of such global recognition. An important technical element for fuel cell development is the development of solid electrolyte materials with high proton conductivity. Currently, practical research is being conducted on solid polymer proton conductors using perfluorosulfonic acid type cation exchange resin, but water is required as a proton transfer medium. Due to problems, the upper limit of the operating temperature is generally limited to about 80 ° C.

On the other hand, the preferred operating temperature of the fuel cell is considered to be 100 ° C. or higher, particularly 150 ° C. or higher, from the viewpoints of energy efficiency and waste heat utilization. An inorganic solid acid typified by cesium hydrogen sulfate is attracting attention as an electrolyte material that satisfies this temperature condition (see Patent Document 1). For example, cesium hydrogen sulfate undergoes a structural phase transition at around 143 ° C. or more, and changes to a solid phase state having a high proton conductivity called a super proton conduction phase. (The super proton conduction phase refers to a solid state having a proton conductivity of 10 ⁻³ S / cm or more (see Non-Patent Document 1).) By using the state of this super proton conduction phase as a solid electrolyte material Therefore, the fuel cell can be operated in a preferable operating condition. In addition, cesium dihydrogen phosphate (CsH ₂ PO ₄ ), triammonium hydrogen sulfate ((NH ₄ ) ₃ H (SO ₄ ) ₂ ), dicesium hydrogen bisulfate (Cs ₂ (HSO ₄ ) (H ₂ PO ₄ )), cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ), etc., several kinds of inorganic solid acids have been reported to exhibit the same superprotonic conduction phase (non-patent) Reference 2, Non-patent document 3, Non-patent document 4).

In order to develop high proton conductivity even below the transition temperature to the super proton conducting phase, a method of suppressing phase transition by mixing with a substance having fine pores such as silica gel (patent document 2, non-patent document 5, non-patent document Patent Document 6) and a method for improving conductivity near room temperature by mixing with an organic polymer having water retention (see Patent Document 3) are known. These are common in that they are produced by mixing an inorganic solid acid and a solid as an additive, and are collectively referred to as a mixed proton conductor here.

Special Table 2004-537834 JP2005-183121 Japanese Patent Application No. 2007-284846 Nature, vol.410, pp.910-913 (2001) Journal of Materials Science Letters, vol.16, pp.2011-2016 (1981) Solid State Ionics, vol.136-137, pp.229-241 (2000) JournalofThe Electrochemical Society, vol.155, pp.B958-B962 (2008) JournalofThe Electrochemical Society, vol.153, pp.A339-A342 (2006) Solic State Ionics, vol.179, pp.1170-1173 (2008)

In general, these mixed proton conductors are physically mixed, for example, by impregnating an aqueous solution of an inorganic solid acid with a solid as an additive, or by rubbing a solid inorganic solid acid and an additive with a mortar. However, there is a problem that the electromotive force is slightly low when actually operating as a fuel cell. (Fig. 8 of Non-Patent Document 5) A low electromotive force means that the efficiency as an energy conversion device is impaired, and as a fuel cell that is characterized by being able to achieve higher efficiency than competing technologies, It is a problem that must be solved.

As the reason for the low electromotive force, Non-Patent Document 5 concludes that hydrogen gas slightly leaks from the fuel electrode side to the oxygen electrode side when operating as a fuel cell. It also points out that the density of the synthesized material is low as a cause of leakage. Further, as disclosed in Non-Patent Document 5, when this material is heated once and then cooled, it reversibly returns to a low-temperature phase and exhibits a phase transition when heated again. This indicates that there is a possibility that the material is deformed with a volume change at every shutdown cycle, and the performance of the fuel cell is impaired by a mechanism such as a minute gap and leakage of hydrogen gas. The possibility cannot be denied.

Needless to say, further improvement in electrical conductivity is necessary to avoid a decrease in efficiency due to resistance loss during operation. Therefore, in order to put the inorganic solid acid electrolyte into practical use, a new method for producing an excellent proton conductor having higher electric conductivity than the conventional one, no phase transition and high electromotive force is required. The present invention provides a new method for producing a proton conductor for an electrochemical energy conversion device, which can obtain a higher electric conductivity and voltage than conventional ones, and solves the problem of phase transition. Provided are a large-capacity capacitor and a fuel cell used as an electrolyte.

The present inventors to achieve the above object diligent research, cationic R ^{i +} a first oxidizing anions Y _p O _q alkaline solution of the ^j- second oxidizing anions X _r O _A method for producing a proton conductor, characterized by neutralizing with a solution of _s ^k− , has been developed. In addition, the mixed proton conductor synthesized by this neutralization reaction has a different phase transition behavior from the proton conductor produced using the conventional physical mixing method, and exhibits high electrical conductivity, It has been found that when used in a fuel cell, a voltage higher than that of a conventional mixed proton conductor is generated. That is, the present invention is ^(are R Na, K, Rb, is one selected from one or ammonium ion of an element selected from the herd consisting of Cs.) Cation R ^{i +} a cation R ^{i +} represented by , First oxide anion Y _p O _q ^j- (wherein j is an integer of 3 to 4, p and q are positive integers, Y is an element selected from the group consisting of Al and Si) An alkaline aqueous solution in which the first oxide anion Y _p O _q ^{j− represented} by the formula (1) is dissolved, and the second oxide anion X _r O _s ^k− (wherein k is 1 to 4). X is an element selected from the group consisting of P, S, and Se, and r and s are positive integers.) The acidity of the second oxide anion X _r O _s ^k- A proton conductor reacted with an aqueous solution. In the present invention, the first oxide anion has an amorphous structure, and the second oxide anion can be bonded to a proton. Furthermore, the present invention is a proton conductor in which no phase transition is observed by a differential thermal analyzer when it is heated to a temperature of 150 ° C. or higher, cooled to room temperature, and further heated to 150 ° C. The present invention also provides a fuel cell using such a proton conductor as an electrolyte. Furthermore, the present invention is a large capacity capacitor using such a proton conductor as an electrolyte.

Further, the present invention is ^(are R Na, K, Rb, is one selected from one or ammonium ion of an element selected from the herd consisting of Cs.) Cation R ^{i +} a cation R ^{i +} represented by during the first oxide anions _Y p _{O q} ^j- (wherein, j is an integer from 1 to 4, p, q are positive integers, Y is Al, an element selected from the herd consisting of Si An alkaline aqueous solution in which the first oxide anion Y _p O _q ^{j− represented} by the formula (1) is dissolved, and the second oxide anion X _r O _s ^k− (wherein k is 1 to X is an element selected from the group consisting of P, S, and Se, and r and s are positive integers.) Of the second oxide anion X _r O _s ^k- This is a method for producing a proton conductor by reacting with an acidic aqueous solution. Further, in the present invention, the cation ^{R i +} a first oxide anion _Y p _{O q} ^j- composition ratio of ^{alkalinity j-} cation ^{R i +} a first oxidizing anions _Y p _{O q} is dissolved The composition ratio of the aqueous solution can be such that the required amount of the first oxide can be dissolved. Furthermore, in the present invention, in the neutralization reaction by first oxidizing anions Y _p O _q ^j- and the second oxidizing anions X _r O _s ^k-, the concentration of the two kinds of oxide anions aqueous solution used By adjusting, the characteristics of the electrolyte can be controlled. In the present invention, adjusted in the neutralization reaction by first oxidizing anions Y _p O _q ^j- and the second oxidizing anions X _r O _s ^k-, the ratio of the two kinds of oxide anions aqueous solution used By doing so, the characteristics of the electrolyte can be controlled. Furthermore, the present invention is a method of activating a proton conductor characterized in that such a proton conductor is heat-treated at 150 to 300 ° C.

The present invention is a new proton conductor, and produces a mixed proton conductor exhibiting high proton conductivity and exhibiting a phase transition behavior different from that of a proton conductor manufactured by using a conventional physical mixing method. be able to. Furthermore, in this invention, the proton conductor which has various characteristics can be made with the addition ratio of cation Ri ⁺ , 1st oxide anion, and 2nd oxide anion. Further, when used in a fuel cell, a voltage higher than that of a conventional mixed proton conductor can be obtained.

In the present invention, the proton conductivity by reacting with a cation R ^{i +} a first oxidizing anions Y _p O _q ^j- shadows oxidizing alkaline aqueous solution prepared by dissolving the second ion X _r O _s ^k-acidic aqueous solution The body manufacturing method will be described in detail. Although the cation R ^{i +} is not particularly limited, at least one selected from ions consisting of elements of Group 1A, Group 4A and Group 4B of the long-period periodic table, and ammonium ion can be preferably used. For example, alkali metal ions such as Na ⁺ , K ⁺ , Cs ⁺ , Rb ⁺ are preferable, but not limited thereto.

First oxidizing anions _Y p _{O q} ^j- is Y = B, Al, Si, Y, Sc, can be preferably used one selected from oxides of the elements is La not limited thereto. Silicate ions are particularly preferable. As silicate ions, various chemical species such as SiO ₃ ²⁻ , Si ₂ O ₇ ⁶⁻ , Si ₄ O ₁₁ ⁶⁻ , Si ₆ O ₁₈ ¹²⁻ are known in addition to orthosilicate ions SiO ₄ ^4−. Yes. The second oxidizing anions, preferably ^k- anion _X r _O ^s of oxo acids, typically ^{_{(SO 4) 2-, (PO}} 4) 3-, (SeO 4) 2-, (ClO ₄₎ ^- can be mentioned but not limited to this. The combination of the cation and the first oxide anion is not particularly limited as long as an alkaline aqueous solution can be formed, but a combination of alkali metal ions such as Na ⁺ , K ⁺ , Cs ⁺ and Rb ⁺ and silicate ions. Can be used particularly preferably.

The combination of the cation and the second oxide anion is not particularly limited as long as it is the above, but it is particularly preferable if it is known to constitute an inorganic solid acid proton conductor. Examples of such substances include CsHSO ₄ , CsH ₂ PO ₄ , KH ₂ PO ₄ , KHSO ₄ , NH ₄ HSO ₄ , RbHSO ₄ , CsHSeO ₄ , Rb ₃ H (SeO ₄ ) ₂ , (NH ₄ ). ₃ H (SO ₄ ) ₂ , K ₃ H (SO ₄ ) ₂ , H ₃ OClO _{4 and the} like are known. Moreover, there is also a mixed acid type containing two or more types of anions, Cs ₂ (HSO ₄ ) (H ₂ PO ₄ ), Cs ₃ (HSO ₄ ) ₂ [H _2-x (P _1-x S _x ) O ₄ ] Is known. The combination of the first oxide anion and the second oxide anion is not particularly limited as long as it is as described above, but those that react with each other to produce a stable inorganic compound are particularly preferable. As an example of such a combination, silicic acid can be cited as the first oxide anion, and phosphoric acid can be cited as the second oxide anion. When these two types of oxides are mixed and heated, they are referred to as SiP ₂ O _7. It is known to produce a stable compound, and when this combination is used in the present invention, it can be expected to produce a stable solid. By way of example a combination the same effect can be expected to produce aluminum phosphate, the first oxide anions as aluminate ions (AlO ₃ ^3-), the combination of phosphate ions as the second oxide anions Can be mentioned.

In the present invention, the cation R ^{i +} a first oxidizing anions Y _p O _q ^j- shadows oxidizing alkaline aqueous solution prepared by dissolving the second ion X _r O _s ^k-means to react with the acidic aqueous solution of a known Technology can be used. For example, an acidic aqueous solution can be dropped dropwise while stirring an alkaline aqueous solution with a magnetic stirrer. The reaction temperature may be room temperature, but it can also be carried out in a heated or cooled state. The dropping speed is preferably about 10 seconds to 3 hours until the dropping is completed, but may be adjusted. When dropping, it may be performed while monitoring the pH of the solution, and a procedure for stopping or restarting dropping may be taken. In particular, when silicic acid is used as the first oxide, there is a high possibility of affecting the fine structure of the precipitated substance by stopping the dropping at around pH 10 where precipitation of the silicate begins. Moreover, reproducibility can be improved by making it complete | finish dripping with the arrival to the defined pH. The composition of the cationic R ^{i +} a first oxidizing anions Y _p O _q ^j- alkaline aqueous solution of can be any percentage of long as it can be dissolved the first oxide by a required amount However, for example, in the case of cesium and silicic acid, a well-known composition of a water-soluble compound such as Cs ₄ SiO ₄ can be preferably used.

Further, the concentrations of the two types of aqueous solutions used for the neutralization reaction can be adjusted so as to obtain the best characteristics of the obtained electrolyte. Further, the ratio of the two types of aqueous solutions can be adjusted so as to obtain the best characteristics of the electrolyte obtained. When it is necessary to manage this ratio, it is convenient to use the pH at the end of neutralization. After the reaction is completed, a solid product can be obtained by removing moisture from the solution, but the means for drying is not particularly limited. For example, known techniques such as heating with a hot plate at about 150 ° C., vacuum drying, and contact with a desiccant can be used. A known technique can be used as a means for molding the solid obtained by drying. For example, pressure molding may be performed by a hydraulic press, but the method is not limited to this, and a method of coating by mixing with a solvent may be used. Further, in order to proceed with the above drying step in a lump, a method of applying the solution as it is after completion of the reaction and drying it as it is to obtain a desired shape may be adopted.

As an example of proceeding together with the drying step, the solution after completion of the neutralization reaction is spray deposited on the first electrode plate prepared in advance, and the second electrode plate is stacked after heat drying. A method for producing a fuel cell may be mentioned. Of course, the fuel cell can also be manufactured by pressure-bonding the first electrode plate and the second electrode plate to the electrolyte press-molded by the hydraulic press as described above. The obtained solid electrolyte, or a large-capacity capacitor and a fuel cell incorporating the solid electrolyte can be activated by heat treatment to improve performance. The temperature at which the heat treatment is performed is not particularly limited. For example, by heating for several tens of minutes at 190 ° C., performance at a lower temperature such as 150 ° C. can be improved. In determining the temperature at which the heat treatment is performed, the differential thermal analysis DTA is useful. For example, if the solid electrolyte has a large endothermic peak at 150 ° C. when the temperature of the sample is increased, the heat treatment is performed at 150 ° C. or higher, and characteristics at lower temperatures such as electrical conductivity, fuel cell, etc. The electromotive force and output power can be improved.

First, an alkaline aqueous solution in which the cation Cs ⁺ and the first oxide anion SiO ₄ ⁴⁻ were dissolved was prepared.
Although the manufacturing method of this aqueous solution is not specifically limited, For example, the following method can be used.
A mullite crucible was weighed with 3.00 g of silicic acid SiO ₂ [Mw = 60.08] and cesium carbonate Cs ₂ CO ₃ [Mw = 325.819] and heated to 990 ° C. completely in an electric furnace. Since it melted, it was poured into an aluminum plate after about 20 minutes and solidified. This solid is pulverized, and water is added to the obtained solid (2.71 g) to completely dissolve it to a total volume of 35 ml to obtain an alkaline aqueous solution in which the cation Cs ⁺ and the first oxide anion SiO ₄ ^4- are dissolved. It was.
While stirring this aqueous solution, an aqueous phosphoric acid solution (an aqueous solution containing 10% liquid phosphoric acid [85%, MW = 97.995] in a total volume of 50 ml) containing the second oxide anion PO ₄ ³⁻ As the solution was added dropwise, the solution gradually became a gel. The operation was terminated when 8.91 ml of an aqueous phosphoric acid solution was dropped. In addition, the electrical conductivity of the proton conductor obtained by adjusting the amount of the phosphoric acid aqueous solution dripped changes.

The obtained gel-like solution was evaporated and solidified on a hot plate. When this solid X-ray powder diffraction measurement was performed, a diffraction pattern different from that of the substance disclosed in Non-Patent Document 5 composed of the same element was shown. (FIG. 1) In Non-Patent Document 5, silicic acid corresponding to the first oxide constitutes crystalline SiP ₂ O ₇ , and the diffraction pattern is the sum of SiP ₂ O ₇ and CsH ₅ (PO ₄ ) ₂ . It has become. On the other hand, in FIG. 1, the diffraction peak of SiP ₂ O ₇ is not seen, and a diffraction pattern that is considered to be composed of CsH ₅ (PO ₄ ) ₂ and a very small amount of CsH ₂ PO ₄ is shown. From the above, it is clear that the structure is different from the substance disclosed in Non-Patent Document 5.

Powder X-ray diffraction measurement was performed while heating this solid. As a result, the diffraction disappeared at around 140 ° C., and the scattering considered to be amorphous was observed. After heating to 200 ° C. and maintaining the temperature for 20 minutes, the powder was cooled to room temperature and subjected to powder X-ray diffraction measurement. As a result, only similar amorphous scattering was observed. When the powder X-ray diffraction measurement was performed by allowing it to stand at room temperature for 3 hours as it was, only the similar amorphous scattering was observed. (FIG. 2) Note that the diffraction peak observed near 2-theta = 38.4 degrees is diffraction from aluminum of the sample holder. Non-Patent Document 4 describes that when CsH ₅ (PO ₄ ) ₂ is melted at a melting point (about 153 ° C.) and then cooled, a crystalline component appears. In this respect, it is considered that a substance different from the substance disclosed in Non-Patent Document 4 is generated.

This solid was filled in a mold, and a pellet having a diameter of 15.0 mm and a thickness of 1.6 mm was molded and prepared using a hydraulic press having a pressure of 392 MPa. The pellet was broken in the thickness direction, the cleavage plane was observed with a manipulation electron microscope (SEM), and the element distribution was examined with an energy dispersive X-ray detector (EDX). The results are shown in FIGS. It can be seen that the structure and composition are almost uniform throughout the pellet. As shown in Comparative Example 1, in the proton conductor obtained from the method of physically mixing the solid acid and silica gel described in Patent Document 2, coarse particles and pulverized fine particles are observed as Si is SiO _2. It was done. From this, it is clear that the structure is different from the proton conductor described in Patent Document 2.

This solid was filled in a mold, and a pellet having a diameter of 15.0 mm and a thickness of 1.6 mm was molded and prepared using a hydraulic press having a pressure of 392 MPa. A platinum-supporting carbon electrode (Pt / C electrode) having a diameter of 13.00 mm was attached to the pellet. The electrical conductivity was evaluated using this pellet. The same proton conductivity measuring apparatus as that used in Patent Document 3 was used. First, the temperature dependence in a dry N ₂ gas atmosphere and a wet N ₂ gas atmosphere was examined. The results are shown in FIG. 3 and FIG. In the figure, the measurement result of CsH ₂ PO ₄ is also shown for comparison. The third and fourth times showed almost the same characteristics as the second time.
In a dry atmosphere, high conductivity was exhibited over the entire temperature range as compared with CsH ₂ PO ₄ alone. In particular, the conductivity was high below the phase transition temperature (about 200 ° C.), and no conductivity jump due to the phase transition was observed.
The electric conductivity in the vicinity of 200 ° C. was clearly higher than the electric conductivity value described in Non-Patent Document 5.
The temperature dependence of the electrical conductivity shown in FIG. 3 is similar to that of CsH ₅ (PO ₄ ) ₂ described in Non-Patent Document 4, and a novel substance containing a phosphate unit is used for the mechanism of proton conduction. Presumed to be involved.

The pellets were then subjected to TG (thermogravimetric analysis) and DTA (differential thermal analysis) measurements under dry N ₂ gas and wet N ₂ gas streams. The results are shown in FIGS. FIG. 5 shows a TG measurement result when the temperature is raised twice while flowing dry nitrogen gas. A decrease in weight, which is considered to be a dehydration reaction, is observed at the first temperature rise, but after it converges, no change in weight is observed at the second time, indicating that a stable substance was obtained.
FIG. 6 shows the result of the DTA measurement simultaneously measured. In the DTA measurement, the endothermic peak that appeared in the vicinity of 140 ° C. at the first temperature increase was not observed at the second temperature increase. This is thought to be due to the irreversible change at the first temperature rise and the disappearance of the phase transition. Further, no endotherm accompanying the phase transition around 220 ° C. occurring in CsH ₂ PO ₄ was observed. This indicates that the phosphate contained in the proton conductor is a substance different from CsH ₂ PO ₄ .
7 and 8 in which the measurement was repeated twice in the same manner in a humid atmosphere, it was found that the phase transition was stable even in the wet atmosphere and disappeared.

FIGS. 9 to 12 show the results of a fuel cell constructed using this pellet and subjected to a power generation test. For measurement, unhumidified air and hydrogen gas were used.
FIG. 9 is a graph of current-voltage characteristics and output power when the cell temperature is raised to 150 ° C. The open circuit voltage (OCV) was 0.703V.
FIG. 10 shows the result of further increasing the temperature to 195 degrees, the OCV is 0.910 V, and FIG. Compared to the OCV of 0.75 V disclosed in FIG. The output was 19.5 mw / cm ² .

In order to measure the performance at the time of restart, FIG. 11 shows the result of the measurement after cooling the cell to room temperature after the measurement of FIG. 9 and heating it to 150 ° C. again. The OCV is 0.908 V, and it can be seen that the electrolyte was activated by the first heating, and changed to a state where a high OCV was obtained even at 150 ° C.
When a similar test was performed on another sample, an open circuit voltage of 0.955 V was obtained at 165 ° C. as shown in FIG.

In order to compare the structure of the solid first oxide anion portion obtained in Example 1 with existing silicon dioxide, the solid obtained in Example 1 was added with distilled water to dissolve the second oxide anion, Insoluble matter was suction filtered, washed with distilled water, and then air-dried to obtain a measurement sample.

The Raman scattering spectrum and infrared absorption spectrum of this measurement sample were measured at room temperature. For the Raman scattering spectrum, argon laser light having a wavelength of 488 nm was used as a light source. The infrared absorption spectrum was measured with a diamond anvil cell sandwiched with a small thickness. The results are shown in FIGS. As an example of the existing amorphous silicon dioxide, the spectrum of the silica gel desiccant measured in the same manner is also shown. In the Raman scattering spectrum of FIG. 13, the peak profiles near 350 and 1000 cm −1 are characteristic, and it can be seen that the structure is different from existing silicon dioxide. In the infrared absorption spectrum of FIG. 14, a rocking mode near 450 cm-1, due to Si-O-Si bond, a bending mode near 800, 1000 cm-1, and a stretching mode near 1100 cm-1 are observed. It can be seen that the first oxide anion portion has a Si—O—Si bond. Furthermore, since the peak position of the bending mode near 1000 cm-1 is different, it can be seen from the infrared absorption spectrum that the fine structure is different from existing silicon dioxide.

(Comparative Example 1)

In order to compare with the proton conductor prepared in Example 1, a sample was prepared by physically mixing cesium dihydrogen phosphate (CsH ₂ PO ₄ ) and silica gel SiO ₂ disclosed in Patent Document 2, The structure was observed with SEM. Mixing ratio CsH ₂ PO ₄ : SiO ₂ =
A powder CsH ₂ PO ₄ / SiO ₂ mixed at 69.9: 30.1 (molar ratio) = 89.9: 10.1 (weight ratio) was produced as a sample. (Here, SiO ₂ is made of Na ₂ SiO _3. ) CsH ₂ PO ₄ / SiO ₂ which is a mixed powder is pressed in the negative direction with a hand press and molded into a pellet shape, and then O, P, Si, and Cs elements were analyzed. (FIGS. 20 to 24)
As shown in FIG. 22, in the analysis of Si, coarse particles and fine particles obtained by pulverizing Si as SiO ₂ were observed. In the EDX analysis of the mixture by this manufacturing method according to Example 1, Si is almost uniformly dispersed as shown in FIG. From this, it is clear that the structure of the proton conductor described in Patent Document 2 is different from the structure of the proton conductor according to the present invention.

Weigh out 2.24 g of potassium hydroxide KOH [Mw = 56.11] and put 0.78 g of aluminum hydroxide Al (OH) ₃ [Mw = 78] in a 10 ml mullite crucible containing the potassium hydroxide. Heated. Since a sound that evaporates at 430 ° C. was heard, the heating was stopped, and the sample was heated to 980 ° C. after the sound had subsided. When it was allowed to cool after being held for 10 minutes, it turned into a white solid except for a small amount of a slightly brownish powder that seemed to be unreacted alumina. The obtained white solid was pulverized, 20 g of water was dissolved in 0.20 g of the solid, dissolved, and filtered through 5c filter paper to dissolve the cation K ⁺ and the first oxide AlO ₃ ^3- in an alkaline aqueous solution. Got.
While stirring this aqueous solution, an aqueous solution of phosphoric acid (10 ml of liquid phosphoric acid [85%, MW = 97.995] in a total volume of 50 ml), which is an acidic aqueous solution containing the second oxide PO ₄ ^3- It was dripped. When the pH of the solution reached 3.03, the solution was evaporated and solidified on a hot plate to obtain a proton conductor.

Weigh 3.00 g of silicic acid SiO ₂ [Mw = 60.08] and cesium carbonate Cs ₂ CO ₃ [Mw = 325.819] in a crucible and heat it to 990 ° C. in an electric furnace to completely melt it. Therefore, after about 20 minutes, it was poured into an aluminum plate and solidified. This solid was pulverized, and 20 g of water was added to 0.61 g of the obtained solid to completely dissolve it, thereby obtaining an alkaline aqueous solution in which the cation Cs ⁺ and the first oxide SiO ₄ ⁴⁻ were dissolved.
When this aqueous solution was stirred, an acidic aqueous solution containing the second oxide SO ₄ ^4- , a sulfuric acid aqueous solution (10 ml of liquid sulfuric acid [98%, MW = 98] was made 50 ml in total volume) was added dropwise. It gradually became cloudy. When the pH of the solution reached 2.03, the obtained solution was evaporated and solidified on a hot plate to obtain a proton conductor.

Since the new proton conductor obtained in the present invention can be used as an electrolyte for fuel cells and large-capacity capacitors, it is an extremely useful material for automobiles and generators using these, and has high industrial applicability. Is.

Powder X-ray diffraction pattern of proton conductor obtained in Example 1 Powder X-ray diffraction pattern after heating the proton conductor obtained in Example 1 to 200 ° C. and cooling to room temperature Dry conductivity of proton conductor obtained in Example 1 Wet conductivity of proton conductor obtained in Example 1 Dry TG of proton conductor obtained in Example 1 Dry DTA of proton conductor obtained in Example 1 Wet TG of proton conductor obtained in Example 1 Wet DTA of proton conductor obtained in Example 1 The first electromotive force measurement 1 of the electrolyte obtained in Example 1, data of a 150 ° C. dry atmosphere. OCV is 0.703V The first measurement of the electrolyte obtained in Example 1, data of 195 ° C. dry atmosphere. OCV = 0.910V The second measurement of the electrolyte obtained in Example 1, data at 150 ° C. dry atmosphere. OCV = 0.908V First measurement 2 of electrolyte obtained in Example 1, data of 165 ° C. dry atmosphere OCV = 0.955V Raman scattering spectrum of a residue sample obtained by washing the proton conductor obtained in Example 1 with water Infrared absorption spectrum of a residue sample obtained by washing the proton conductor obtained in Example 1 with water SEM image (× 3000) of the proton conductor obtained in Example 1 EDX element mapping (O) of proton conductor obtained in Example 1 EDX element mapping (Si) of proton conductor obtained in Example 1 EDX element mapping of the proton conductor obtained in Example 1 (P) EDX element mapping (Cs) of proton conductor obtained in Example 1 SEM image of proton conductor obtained in Comparative Example 1 (× 3000) EDX element mapping of the proton conductor obtained in Comparative Example 1 (O) EDX element mapping (Si) of proton conductor obtained in Comparative Example 1 EDX element mapping of proton conductor obtained in Comparative Example 1 (P) EDX element mapping (Cs) of proton conductor obtained in Comparative Example 1

Claims (11)

Cation R ^{i +} (wherein i is an integer, R is one element selected from the group consisting of Na, K, Rb, and Cs or one element selected from ammonium ions) and anion Y _p O _q ^j- (wherein j, p and q are positive integers, Y is one element selected from the group consisting of Al and Si) Y _p An alkaline aqueous solution in which O _q ^j− is dissolved is an anion X _r O _s ^k− (wherein k is a positive integer, X is an element selected from the group consisting of P, S, Se, and r and s are positive integers.) A proton conductor reacted with an acidic aqueous solution of the second oxide anion X _r O _s ^k- . The proton conductor according to claim 1, wherein the first oxide anion has an amorphous structure, and the second oxide anion is bonded to a proton. 3. The proton conductor according to claim 1, wherein, when heated to a temperature of 150 ° C. or higher, cooled to room temperature, and further heated to 150 ° C., a phase transition is not observed by a differential thermal analyzer. An electrochemical device using the proton conductor according to any one of claims 1 to 3. A fuel cell using the proton conductor according to any one of claims 1 to 3 as an electrolyte. A high-capacity capacitor using the proton conductor according to any one of claims 1 to 3 as an electrolyte. Cation R ^{i +} (wherein i is an integer, R is one element selected from the group consisting of Na, K, Rb, and Cs or one element selected from ammonium ions) and anion Y _p O _q ^j- (wherein j, p and q are positive integers, Y is one element selected from the group consisting of Al and Si) Y the _p O _q ^j- and alkaline aqueous solution of the anion _X r _O ^{s k-} (wherein, k is a positive integer, X is located in the element selected from the herd comprising P, S, Se, , R, and s are positive integers). A method for producing a proton conductor by reacting with an acidic aqueous solution of the second oxide anion X _r O _s ^k— . Cations R ^{i +} a first oxide anion Y _p O _q ^j- composition ratio of an aqueous solution of an alkaline ^{to j-} cation R ^{i +} a first oxidizing anions Y _p O _q is dissolved, first The method for producing a proton conductor according to claim 6, wherein the composition ratio is within a range in which a required amount of oxide can be dissolved. In the neutralization reaction by the first oxide anion Y _p O _q ^j− and the second oxide anion X _r O _s ^k− , the characteristics of the electrolyte are adjusted by adjusting the concentration of the two types of aqueous oxide anions used. The method for producing a proton conductor according to claim 6, wherein the proton conductor is controlled. In the neutralization reaction by first oxidizing anions Y _p O _q ^j- and the second oxidizing anions X _r O _s ^k-, by adjusting the ratio of the two kinds of oxide anions aqueous solution used, the electrolyte properties The method for producing a proton conductor according to claim 6, wherein the proton conductor is controlled. A method for activating a proton conductor, comprising subjecting the proton conductor according to any one of claims 1 to 3 to heat treatment at 150 to 300 ° C.

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