JP2006134838A - Electrode, solid electrolyte membrane joined with the electrode, and electrochemical system using the solid electrolyte membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive electrode, a solid electrolyte membrane joined with the electrode and an electrochemical system in which when they are used in a direct methanol type fuel cell, the solid electrolyte does not eluate, and in which they are applicable to applications to use electrode components which could not be contacted with a strong acid. <P>SOLUTION: The electrode contains a complex compound comprising: an organic compound obtained by neutralizing at least one salt of silicic acid, tungstic acid, molybdic acid and stannic acid with an acid, or neutralizing zirconium halide or zirconium oxyhalide with an alkali, in a raw solution in which an organic compound containing an organic polymer having a hydroxyl group coexists; at least one inorganic compound of a silicic acid compound, tungstic acid compoud, molybdic acid compound, stannic acid compound and zirconic acid compound; and water. The solid electrolyte membrane joined with the electrode, and the electrochemical system using the solid electrolyte membrane are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrode applicable to an electrochemical system using a proton (hydroxide ion) conductive solid electrolyte such as a fuel cell, a solid electrolyte membrane joined with the electrode, a fuel cell using the solid electrolyte membrane, and other It relates to electrochemical systems.

Conventionally, there are many types of electrochemical systems that use proton (hydroxide ion) conductive solid electrolytes or that can be used in principle. For example, solid polymer fuel cells are shown in the following formula (1). Thus, the current is generated by the electrochemical oxidation reaction of hydrogen supplied to the negative electrode, the electrochemical reduction reaction of oxygen supplied to the positive electrode as shown in the formula (2), and the reaction consisting of proton transfer in the electrolyte therebetween. Flow and electrical energy are extracted.
H ₂ → 2H ⁺ + 2e ⁻ ………………………… (1)
_1/2 O ₂ + 2H ⁺ 2e ⁻ → H ₂ O (2)

  There are direct methanol fuel cells in which the fuel supplied to the negative electrode is methanol, and fuel cells that use other fuels such as hydrogen and methanol as the fuel, but in this case as well, the fuel is electrochemically oxidized at the negative electrode. The reaction for releasing protons is performed in the same manner, and can be operated using a proton conductive solid electrolyte.

  In general fuel cells, electrodes are bonded to both sides of a proton-conducting solid electrolyte membrane, fuel is supplied from one side, oxygen (air) is supplied from the other side, and an electric current is supplied to an external circuit that connects the two electrodes. Is configured to flow. A perfluorosulfonic acid ion exchange membrane is usually used as the solid electrolyte membrane, and a conductive carbon powder carrying platinum or a platinum-ruthenium alloy is used as the electrode. In general, a conductive carbon porous body plate or sheet such as carbon paper or carbon cloth is attached to the outside of the carbon powder electrode.

Next, for example, an electrolysis hydrogen generator is put to practical use as an electrolysis apparatus. This electrolysis-type hydrogen generator generates hydrogen by a reaction opposite to the reaction of the above formulas (1) and (2) in a fuel cell, and has high purity on-site only with water and electric power. Since hydrogen is obtained, there is an advantage that a hydrogen cylinder is unnecessary. In addition, electrolysis can be easily performed simply by introducing fresh water not containing an electrolyte by using a solid electrolyte. In the field of paper industry, an attempt has been made to produce bleaching hydrogen peroxide on-site by an electrolytic method using the following formula (3) using a similar system (see Non-Patent Document 1).
O ₂ + H ₂ O + 2e ⁻ → HO ₂ ⁻ + OH ⁻ (3)

  The structure of the electrolyzer is similar to that of the fuel cell, and the basic structure is that electrodes are attached to both surfaces of the solid electrolyte membrane and connected by an external circuit.

A dehumidifier has a structure in which a proton-conducting solid electrolyte is sandwiched between positive and negative electrodes in the same manner as a fuel cell or hydrogen generator. When a voltage is applied between the positive and negative electrodes, water is converted into oxygen by the reaction of the following formula (4) at the positive electrode. Protons decomposed into protons and transferred to the negative electrode through the solid electrolyte are combined with oxygen in the air again by the reaction of the formula (5) and returned to water. As a result of these reactions, water is transferred from the positive electrode side to the negative electrode side. By moving, it is dehumidified on the positive electrode side.
H ₂ O → 1 / 2O ₂ + 2H ⁺ + 2e ⁻ (4)
_1/2 O ₂ + 2H ⁺ 2e ⁻ → H ₂ O (5)

  Water can be decomposed and dehumidified by the same operating principle as the electrolysis-type hydrogen generator, and an air conditioner combined with a water evaporation cooler has also been proposed (see Non-Patent Document 2).

  For example, the hydrogen sensor can use the change in electrode potential due to the hydrogen concentration when hydrogen is introduced in the reactions of the above formulas (4) and (5). Further, it can be applied to a humidity sensor by utilizing a change in electrode potential or a change in ion conductivity.

An electrochromic device utilizes, for example, the fact that when an electric field is applied to the negative electrode using WO ₃ or the like, it develops color by the reaction of the following formula (6), and is considered to be used for a display device or a light shielding glass. This system also operates by exchanging protons to the negative electrode, and a proton conductive solid electrolyte can be used.
WO ₃ + xH ⁺ + xe ⁻ → HxWO ₃ (color development) ……………… (6)

In addition, primary batteries, secondary batteries, optical switches, electrolyzed water production apparatuses, and the like can be cited as electrochemical systems that operate using a proton conductive solid electrolyte in principle. A nickel metal hydride battery as an example of a secondary battery uses a hydrogen storage alloy as a negative electrode, nickel hydroxide as a positive electrode, and an alkaline electrolyte as an electrolyte, as shown in the following formulas (7) and (8): At the time of charging and discharging, electrochemical oxidation-reduction of protons and storage of hydrogen in the hydrogen storage alloy occur at the negative electrode.
[Charging] H ₂ O + e ⁻ → H (Occlusion) + OH ⁻ (7)
[Discharge] H (Occlusion) + OH ⁻ → H ₂ O + e ⁻ (8)

In the positive electrode, an electrochemical oxidation-reduction reaction of nickel hydroxide occurs as shown in the following formulas (9) and (10).
[Charging] Ni (OH) ₂ + OH ⁻ → NiOOH + H ₂ O + e ⁻ (9)
[Discharge] NiOOH + H ₂ O + e ⁻ → Ni (OH) ₂ + OH ⁻ (10)
The charge / discharge reaction of this battery is established by the movement of protons or hydroxide ions in the electrolyte, and in principle, an alkaline electrolyte that is not a solid electrolyte is used, but in principle a proton conductive solid electrolyte is used. Can be used.

For example, an optical switch using yttrium as a negative electrode has been proposed (see Non-Patent Document 3). This is because, by applying an electric field, yttrium is hydrogenated and transmits light as shown in the following equation (11), so that transmission and non-transmission of light can be switched by the electric field. Conventionally, an alkaline electrolyte is usually used in this system, but in principle, a proton conductive solid electrolyte can be used.
Y + 3 / 2H ₂ O + 3e → YH ₃ + 3OH (11)

  Electrolyzed water is water that has undergone an electrolytic reaction, and has different effects on the reducing side and the oxidizing side, but has health-friendly effects, bactericidal action, cleaning action, and action to promote the growth of crops. There are various uses such as washing water and agricultural water. The electrolytic reaction is promoted by the fact that water contains an electrolyte, but if the electrolyte is dissolved in water, it may be necessary to remove the electrolyte during use. When a solid electrolyte is used, there is no need to remove the electrolyte.

  In an electrochemical system using a solid electrolyte, unlike when a liquid electrolyte (electrolyte) is used, the contact between the electrolyte and the electrode surface is insufficient, or the electrolyte does not penetrate into the electrode. The area of the interface between the electrode and the electrolyte is reduced. Since the electrode reaction occurs at the interface between the electrode and the electrolyte, the electrode reaction rate is reduced in an electrochemical system using a solid electrolyte. Therefore, it is desirable to devise a method for increasing the area of the interface between the electrode and the electrolyte as much as possible even in an electrochemical system using a solid electrolyte. For example, in an electrode for a fuel cell, an electrode obtained by solidifying carbon powder supporting a metal catalyst is used, but the reaction area is increased by dispersing a solid electrolyte in the electrode. . For example, when a solid electrolyte is used in a primary battery, a secondary battery, etc., sufficient current cannot be obtained unless the solid electrolyte component is dispersed in the electrode and the area of the interface between the electrode material and the solid electrolyte is increased. At present, solid electrolyte membranes used in fuel cells, electrolyzers, dehumidifiers, etc. are often perfluorosulfonic acid polymers represented by Nafion membranes (Nafion). In addition, in order to disperse the solid electrolyte, for example, a method in which a solution in which a perfluorosulfonic acid polymer is dissolved in a solvent such as alcohol is mixed in an electrode is used.

  By the way, apart from perfluorosulfonic acid based electrolytes, composite compounds of organic polymers having hydroxyl groups and various inorganic compounds have been proposed. For example, polyvinyl alcohol and silicic acid compound (see Patent Document 1), polyvinyl alcohol and tungstic acid compound (see Patent Document 2), polyvinyl alcohol and molybdate compound (see Patent Document 2), polyvinyl alcohol and stannic acid compound (Refer to Patent Document 3), based on a composite compound at the micro level of polyvinyl alcohol and a zirconate compound (refer to Patent Documents 4 and 5), and other components include phosphorus, boron, aluminum, titanium, At least one of calcium, strontium, and barium compounds is added. These can be produced by a simple process of neutralizing a raw material salt of an inorganic compound in a solution in which polyvinyl alcohol coexists, and are characterized by low cost. The polyvinyl alcohol side is combined with an inorganic compound to provide water resistance and proton conductivity as well as strength, and the inorganic compound side is combined with polyvinyl or alcohol to provide flexibility, resulting in high performance. A solid electrolyte is produced. These materials can be treated with aldehyde and acetalization of the hydroxyl group of the polyvinyl alcohol part can suppress excessive swelling due to water absorption (Patent Document 6). Further, these materials may contain at least one of phosphoric acid and boric acid in the neutralized solution in the process of preparing the composite compound by the neutralization method, or at least one of phosphoric acid and boric acid after the formation of the composite compound. By immersing in a liquid containing or applying the liquid, a part or all of the hydroxyl group of the organic polymer having a hydroxyl group in the composite compound is bonded to at least one of phosphoric acid and boric acid. In particular, durability at high temperatures can be increased (see Patent Document 7).

In addition, among the above, composite compounds of polyvinyl alcohol and silicic acid compounds, stannic acid compounds, and zirconic acid compounds are different from conventional solid electrolytes such as perfluorosulfonic acid-based compounds and exhibit high ionic conductivity even in alkaline types. In particular, a compound containing a carboxyl group or a metal salt thereof in a composite compound of polyvinyl alcohol and a zirconic acid compound is an alkaline type and exhibits extremely high ionic conductivity (see Patent Document 5). When the alkali type exhibits high ionic conductivity, it can also be used for primary batteries, secondary batteries, optical switches, etc., which have been difficult to apply in the past. Furthermore, there are secondary batteries that can be easily put into practical use by developing an alkaline solid electrolyte membrane, that is, a high energy density battery using a divalent or higher polyvalent metal as a negative electrode. For example, a nickel zinc battery using zinc oxide as the negative electrode and nickel hydroxide as the nickel metal hydride battery as the positive electrode can be used. In the nickel-zinc battery, as shown in the following formulas (12) and (13), in the negative electrode, zinc oxide is reduced during charging to become metallic zinc, and during discharging, zinc is electrochemically oxidized and returned to zinc oxide. .
[Charging] ZnO + H ₂ O + 2e ⁻ → Zn + 2OH ⁻ (12)
[Discharging] ^{Zn + 2OH - → ZnO + H} 2 O + 2e - ............ (13)

Nickel-zinc batteries have high storage energy due to the fact that zinc is divalent, but there is a problem that it is difficult to put into practical use due to the elution of zinc oxide and the accompanying formation of metal zinc, that is, dendrites and short circuits, or self-discharge problems. is there. However, these problems can be solved by using a solid electrolyte. Even in an air zinc battery using an air electrode as a positive electrode, the diffusion of oxygen to the zinc electrode is suppressed, so there is no risk of self-discharge without cutting off the air supply when not in use, and it can be charged An air battery is also obtained. In addition to zinc, there are many other metals such as copper, cobalt, iron, manganese, chromium, vanadium, tin, molybdenum, niobium, tungsten, silicon, boron, and aluminum. A battery using a valent metal can be put into practical use.
JP 2003-007133 A JP 2003-138084 A Japanese Patent Application Laid-Open No. 2003-208814, Japanese Patent Application No. 2002-4151 Japanese Patent Application No. 2002-35832 Japanese Patent Application No. 2002-310093 Japanese Patent Application No. 2002-86442 Japanese Patent Application No. 2004-173100 Electrochemistry, 69, No. 3,154-159 (2001) 2000 Annual Conference of the Institute of Electrical Engineers of Japan, P3373 (2000) J. Electrochem. Soc., Vol. 143, No. 10, 3348-3353 (1996).

  Currently, perfluorosulfonic acid electrolytes mainly used have a problem of high cost due to the complexity of the manufacturing process. Due to the mass production effect of these electrolytes, there is a limit to what is expected to reduce the price to some extent, and the present situation is that there is a demand for the appearance of inexpensive alternative materials. Since the amount of solid electrolyte used is larger in the solid electrolyte membrane sandwiched between the electrodes, the cost problem is more serious in the solid electrolyte membrane than in the solid electrolyte in the electrode, and alternative materials are also being studied However, the cost of the electrolyte in the electrode is not negligible. Further, when the perfluorosulfonic acid type electrolyte is directly used in a methanol fuel cell as it is, if a high concentration methanol fuel is used, the electrolyte in the electrode is dissolved. When a method such as cross-linking between molecules so as not to dissolve is taken, there arises a problem that the cost is further increased.

  In the case of a primary battery, a secondary battery, etc., when the electrode active material to be used comes into contact with a strongly acidic electrolyte, there arises a problem that it causes corrosion or further dissolves in the electrolyte. In particular, since conventional perfluorosulfonic acid electrolytes are strong acids, they cannot be used as electrolytes contained in electrodes in these applications. This problem also applies to the application of the optical switch, and applies to other applications where a strong acid-resistant material is not used as the electrode material.

  On the other hand, the electrolyte composed of the above-mentioned inorganic / organic composite compound is inexpensive and insoluble in alcohol, and the electrolyte component in the electrode does not dissolve in the methanol fuel even when used directly in a methanol fuel cell. In addition, some alkaline types exhibit high proton conductivity, and can be applied to applications using electrode components that cannot be in contact with strong acids, such as primary batteries and secondary batteries. However, at present, no study has been made on a method for incorporating an electrolyte composed of these inorganic / organic composite compounds into an electrode, or a method for joining the electrode to a solid electrolyte membrane.

  Accordingly, the present invention solves the above-mentioned problems of electrodes containing perfluorosulfonic acid-based electrolytes that have been conventionally provided in electrochemical systems that use solid electrolytes, such as fuel cells, and is a direct and inexpensive methanol fuel. When used in a battery, the electrolyte component in the electrode is not dissolved in the methanol fuel, and the electrode can be applied in applications using an electrode component that cannot be in contact with a strong acid, such as a primary battery or a secondary battery, and the electrode An object of the present invention is to provide a solid electrolyte membrane having electrodes joined thereto and an electrochemical system using the solid electrolyte membrane.

  In order to achieve the above object, the present invention provides at least one salt of silicic acid, tungstic acid, molybdic acid and stannic acid with an acid in a raw material solution in which an organic compound containing an organic polymer having a hydroxyl group coexists. Organic compounds and silicic acid compounds, tungstic acid compounds, molybdic acid compounds, stannic acid compounds, zirconic acid compounds created by neutralizing or neutralizing zirconium halides or zirconium oxyhalides with alkali and removing the solvent An electrode containing a composite compound composed of at least one inorganic compound and water, a solid electrolyte membrane joined with the electrode, and various electrochemical systems using the solid electrolyte membrane are provided.

  The organic polymer having a hydroxyl group is polyvinyl alcohol, and the raw material solution before neutralization contains at least one salt selected from phosphoric acid and boric acid, or an aluminum salt, titanium salt, calcium salt, strontium salt , Barium salt and boric acid, and the composite compound contains at least one of phosphorus, boron, aluminum, titanium, calcium, strontium and barium compounds.

  It can be applied when using carbon carrying a metal catalyst as an electrode component. The electrode is obtained by applying a mixture of the liquid after neutralization in the composite compound preparation process and other electrode components to the surface and joining them by heating to obtain a solid electrolyte membrane. Alternatively, the mixture of the neutralized solution and other electrode components in the composite compound preparation process is applied in advance on a different plane from the solid electrolyte membrane, and the applied product is pressed onto the electrolyte membrane surface by hot pressing to transfer. The solid electrolyte membrane is obtained by coating by heating and joining by heating.

  Electrochemical systems include fuel cells, steam pumps, dehumidifiers, air conditioners, electrochromic devices, electrolyzers, electrolysis hydrogen generators, electrolytic hydrogen peroxide generators, electrolyzed water generators, humidity sensors, hydrogen sensors, primary The present invention can be applied to a battery, a secondary battery, an optical switch system, or a new battery system using a polyvalent metal.

  According to the present invention, at least one salt of silicic acid, tungstic acid, molybdic acid, stannic acid is neutralized with an acid in a raw material solution in which an organic compound containing an organic polymer having a hydroxyl group coexists, or At least one of organic compounds and silicic acid compounds, tungstic acid compounds, molybdic acid compounds, stannic acid compounds and zirconic acid compounds prepared by neutralizing zirconium halide or zirconium oxyhalide with alkali and removing the solvent Electrode containing a composite compound composed of inorganic compound and water and a solid electrolyte membrane joined with the electrode are obtained, the area of the interface between the solid electrolyte membrane and the electrode is sufficiently increased, and the electrode reaction rate is increased. Low-cost electricity with low degradation of performance and the use of solid electrolyte membranes It is possible to provide the academic system.

  In the electrode of the present invention, the electrolyte of the composite compound contained therein is insoluble in alcohol. Therefore, when used in a direct methanol fuel cell, the solid electrolyte is used even when a high concentration methanol fuel is used. The component does not elute. Furthermore, the electrode of the present invention can be applied to applications using an electrode component that cannot contact with a strong acid, such as a primary battery and a secondary battery.

  BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an electrode according to the present invention, a solid electrolyte membrane joined with the electrode, and an electrochemical system using the solid electrolyte membrane will be described below. The electrode of the present invention neutralizes at least one salt of silicic acid, tungstic acid, molybdic acid and stannic acid with an acid in a raw material solution in which an organic compound containing an organic polymer having a hydroxyl group coexists, or At least one of organic compounds and silicic acid compounds, tungstic acid compounds, molybdic acid compounds, stannic acid compounds and zirconic acid compounds prepared by neutralizing zirconium halide or zirconium oxyhalide with alkali and removing the solvent It is characterized by being an electrode containing a composite compound composed of an inorganic compound and water.

  The electrode is used after being joined to the surface of the solid electrolyte membrane. As a joining method, a mixture of the liquid after neutralization in the composite compound preparation process and other electrode components is applied to the surface of the solid electrolyte membrane and then heated. The mixture of the liquid after neutralization in the process of preparing the composite compound and other electrode components is applied in advance on a plane different from the solid electrolyte membrane such as a polyester sheet or film, and the applied product is heated. The method of transferring by pressing against the electrolyte membrane surface by pressing is optimal.

  Specific embodiments of the present invention will be described below based on various examples. In addition, this invention is not limited to the description content of these Examples.

To create a complex compound, firstly the 10 wt% aqueous solution 100cc saponification degree average degree of polymerization of 3,100 to 3,900 is 86 to 90% of polyvinyl alcohol, sodium tungstate dihydrate _{(Na 2 WO} 4 · 2H 2 O) 13 wt%, trisodium phosphate (Na ₃ PO ₄ · 12H ₂ O) 5.4 wt% mixed aqueous solution 11 cc and sodium silicate 15 wt% aqueous solution 8 cc were added to form a raw material aqueous solution. However, 11 cc of hydrochloric acid having a concentration of 2.4 M and 12 cc of 50% by weight of phosphoric acid were added dropwise to neutralize the solution to prepare a viscous precursor aqueous solution. This precursor aqueous solution was put into a sealed container and defoamed by reducing the pressure with a vacuum pump.

  A part of the prepared composite compound solution was used for preparing a solid electrolyte membrane, and the rest was used for inclusion in an electrode. The solid electrolyte membrane composed of the composite compound was prepared by the following method. A polyester film is placed on the smooth base of the coating device (K Control Coater 202, manufactured by RK Print Coat Instruments Ltd.) equipped with a blade that can adjust the gap with the base using a micrometer. The composite compound solution was cast. At this time, the pedestal was heated while being controlled to 50 ° C.

  Immediately after casting the composite compound solution on the pedestal, a blade whose gap was adjusted to 0.6 mm was swept over the composite compound solution at a constant speed to obtain a constant thickness. By leaving it at 50 ° C. as it is, the moisture is removed, and when the fluidity has almost disappeared, the composite compound liquid is cast again from above, and the blade is immediately moved over the composite compound liquid at a constant speed. Swept to a certain thickness. Thereafter, the temperature of the pedestal was raised to 105 ° C. to 110 ° C., and the heat treatment was performed for 1.5 hours while maintaining the state. Thereafter, the film formed on the pedestal was peeled off, dried after washing with hot water.

  The solid electrolyte membrane thus prepared was cut to 100 mm × 100 mm and treated with an aldehyde for suppressing membrane swelling. In the treatment with aldehyde, the solid electrolyte membrane was first immersed in 1.2 M hydrochloric acid for 1 hour at room temperature, and then immersed in 100 cc of 1.2 M hydrochloric acid containing 10 cc of isobutyraldehyde at room temperature for 2 hours. Thereafter, it was washed with hot water at 70 ° C. to 100 ° C. and then dried.

  As an example of an electrode containing a composite compound, a method for producing an electrode made of carbon powder carrying a platinum catalyst as used in a fuel cell will be described. Other types of electrodes can also be produced in the same manner except that the components of the contents are different. First, 1.3 cc of water was placed in a beaker, 0.1 g of fine carbon powder carrying platinum was added, and the mixture was well dispersed by applying ultrasonic waves. After sufficiently mixing, 0.6 g of the composite compound solution prepared by the neutralization method was added, and the mixture was stirred and mixed with a magnetic stirrer. This mixture was applied to the solid electrolyte membrane, dried, and hot pressed at 100 ° C. for 1 hour. Thereafter, it was washed with hot water at 70 ° C. to 100 ° C. and then dried.

  In the heating process, the condensation polymerization of the inorganic components in the composite compound or between the inorganic component and the organic component proceeds, and the composite compound is firmly solidified. That is, when the composite compound is applied as a solid electrolyte contained in an electrode, the electrode components can be easily combined with each other by simple heating, the electrode component and the solid electrolyte membrane can be combined, and a role of a binder can be given. it can. Therefore, the electrode or the joined body of the electrode and the solid electrolyte membrane prepared in this manner is not easily peeled off against physical impact and is stabilized so as not to deteriorate even in hot water. ing. Since the composite compound, which is a solid electrolyte membrane, is dispersed in the electrode prepared in this way, the area of the interface between the electrode and the solid electrolyte is large, and the reactivity is also excellent. In addition, since the composite compound is insoluble in alcohol, unlike a conventional perfluorosulfonic acid material, there is no need to perform special treatment such as crosslinking when directly used as an electrode for a methanol fuel cell. It does not melt out.

  3 shows another method for joining an electrode and a solid electrolyte. The same electrode mixture comprising platinum-supported carbon fine powder, water, and composite compound liquid as in Example 1 was applied onto a polyester (polyethylene terephthalate) film having a size of 50 mm × 50 mm and a thickness of 50 μm. Heating was performed at 50 ° C., and the coated surface was hot-pressed at 100 ° C. for 1 hour together with the same solid electrolyte membrane as in Example 1 in a state where the coated material was almost dry. When the polyester film was peeled off after hot pressing, only the polyester film was peeled off cleanly, and the electrode was transferred onto the solid electrolyte membrane. Thereafter, the joined body of the electrode and the solid electrolyte membrane was washed with hot water at 70 ° C. to 100 ° C. and then dried. Similarly to the case of Example 1, the electrode and the electrode / solid electrolyte membrane assembly produced in this way are bonded firmly to each other, or the electrode and the solid electrolyte membrane are physically strong and heat-resistant. Even in water, it does not deteriorate and is stable. Since the composite compound is dispersed in the electrode, the reactivity is excellent, and the composite compound in the electrode does not dissolve in the alcohol. When the electrode coating is applied directly to the solid electrolyte membrane as in Example 1, the electrode coating portion of the solid electrolyte membrane is slightly expanded by the moisture of the coating, and the membrane is likely to be deformed. Such a problem can be avoided by applying an electrode coating on another film in advance as in the present embodiment and transferring it with a hot press. In the method of this embodiment, the position where the electrode is attached, the electrode size, and the shape can be controlled easily and precisely, and the industrial merit is great.

  In Examples 1 and 2, tungstic acid is the main component as an inorganic component of the composite compound, but instead, the composite compound mainly composed of a zirconate compound, a stannic acid compound, and a silicate compound has excellent stability in an alkali. Since the proton (or hydroxide ion) conductivity is high when the alkali type is used, the present invention can be applied to applications where an acid type solid electrolyte such as a primary battery and a secondary battery cannot be used. Even in that case, an electrode containing the composite compound can be prepared by the same method as in the example, and the electrode can be joined to the solid electrolyte membrane by the same method.

  Examples of the organic polymer having a hydroxyl group in the present invention include polyvinyl alcohol, various celluloses, polyethylene glycol, or those obtained by introducing a hydroxyl group into various organic polymers, or those obtained by copolymerization or graft polymerization of an organic polymer having a hydroxyl group. . For example, polyvinyl alcohol is the most representative for the present invention, but polyvinyl alcohol does not need to be complete and can be used as long as it essentially functions as polyvinyl alcohol. For example, those in which a part of the hydroxyl group is substituted with another group and those in which another polymer is copolymerized or graft polymerized to a part can also function as polyvinyl alcohol. Moreover, since the same effect is acquired if it passes through polyvinyl alcohol in a reaction process, the polyvinyl acetate etc. which are the raw materials of polyvinyl alcohol can also be used as a starting material.

  In addition, other polymers such as polyolefin polymers such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polytetrafluoroethylene, and polyfluoride can be used as long as the function of the organic polymer having a hydroxyl group is sufficiently developed. Fluorine polymers such as vinylidene, polyvinyl acetate polymers, polystyrene polymers, polycarbonate polymers, epoxy resin polymers, or other organic and inorganic additives may be mixed.

  An inorganic compound salt is neutralized with an acid or alkali in a raw material solution in which an organic compound containing an organic polymer having a hydroxyl group coexists, and a solvent is removed to prepare a composite compound composed of the organic compound, the inorganic compound, and water. In this case, a typical example of the inorganic compound salt is a metal oxyacid salt. For example, at least one metal salt of silicic acid, tungstic acid, molybdic acid, and stannic acid can be used. In this case, an acid is used for neutralization. The metal salt of silicic acid, tungstic acid, molybdic acid, and stannic acid can be any type of metal salt that dissolves in the solvent used, and any type of metal ion, oxygen, cation ratio, or moisture content. Something like that. Another example of the inorganic compound salt is zirconium halide or zirconium oxyhalide, and an alkali is used for neutralization. Zirconium salts and oxyzirconium salts may be of any kind as long as they are soluble in the solvent used, and zirconium chloride, zirconium oxychloride and the like can be used. Any ratio of oxygen and anion, and water content may be used. The solvent of the raw material solution may be any solvent as long as it can dissolve the metal salt and organic polymer as raw materials, but water is preferable in terms of the high solubility of the metal salt. In addition, the metal salt of silicic acid, tungstic acid, molybdic acid and stannic acid as raw materials is preferably an alkali metal salt in terms of solubility.

  At least one of phosphorus, boron, aluminum, titanium, calcium, strontium, and barium compounds can be included in the composite compound that forms the solid electrolyte. At least one metal salt selected from phosphoric acid and boric acid is included in the previous raw material solution, or at least one selected from aluminum salt, titanium salt, calcium salt, strontium salt, barium salt and boric acid It is done by including. The metal salt of phosphoric acid and boric acid may be any kind as long as it is soluble in the solvent used, and any kind of metal ion, oxygen / cation ratio, and water content may be used. However, it is preferable to use an alkali metal salt in terms of the solubility of the metal salt. Any kind of aluminum salt, titanium salt, calcium salt, strontium salt and barium salt may be used as long as they are soluble in the solvent used, and any kind of anion and moisture content may be used. In addition, when adding phosphorus, boron, silicon, tungstophosphoric acid, molybdophosphoric acid, silicotungstic acid, silicomolybdic acid, tungstoboric acid, molybdoboric acid, etc. in which tungstic acid or molybdic acid and phosphoric acid, silicic acid, boric acid are combined in advance Heteropolyacid or its salt can be used as a raw material.

  The type of acid or alkali used for neutralization in the preparation of the composite compound is any metal that can neutralize silicic acid, tungstic acid, molybdic acid, stannic acid metal salt, zirconium chloride, zirconium salt, or oxyzirconium salt. Hydrochloric acid, sulfuric acid, phosphoric acid, sodium hydroxide, lithium hydroxide, etc. can be used.

  In the present invention, the method of incorporating the composite compound in the electrode is not necessarily limited to the method described in the examples, and any method can be used as long as the composite compound can be dispersed in the electrode. Good. For example, the composite compound can be included in the electrode by immersing the electrode in a liquid containing the composite compound after forming the electrode, or by applying a liquid containing the composite compound to the electrode.

  In the embodiment, the solid electrolyte membrane to which the electrode is joined is also a composite compound having the same component as that contained in the electrode, but it is not necessarily the same. For example, the composite compound-containing electrode of the present invention may be joined to an electrolyte membrane of a completely different system such as a perfluorosulfonic acid system that has been conventionally used. However, when the solid electrolyte membrane to be joined is made of an electrolyte composed of the same type of composite compound as contained in the electrode, there are merits such as better jointability.

  The solid electrolyte of the present invention promotes bond formation with an inorganic compound and an organic compound by heat treatment at a temperature of 100 ° C. or higher, and increases strength, water resistance, and high-temperature stability in an electrode or a membrane-electrode assembly. Can do. At that time, the atmosphere in the heat treatment may be in air, in an inert gas atmosphere, or in a vacuum.

  In the present invention, the mixture of the liquid after neutralization in the composite compound preparation process and other electrode components is applied in advance on a film or sheet different from the solid electrolyte membrane, and the applied material is subjected to an electrolyte membrane by hot pressing. The electrode is bonded to the surface of the solid electrolyte membrane by a method of pressing on the surface and transferring onto the surface of the electrolyte membrane. The material of the film or sheet used at this time is the film or sheet that can be easily peeled off after hot pressing, and only the electrode Any material can be used as long as it remains on the electrolyte membrane. However, if the affinity with the coating is low and the coating is easy to repel, the electrode cannot be formed well on the film or sheet. On the other hand, if the affinity with the coating is too high, only the film or sheet cannot be peeled after hot pressing, and the electrode cannot be transferred onto the electrolyte membrane. Therefore, it is preferable that the material of the film or sheet has an appropriate affinity with the coated material, and polyester such as polyethylene terephthalate is suitable in that respect.

  As described above, the present invention can neutralize at least one salt of silicic acid, tungstic acid, molybdic acid and stannic acid with an acid in a raw material solution in which an organic compound containing an organic polymer having a hydroxyl group coexists. Or an organic compound and a silicic acid compound, a tungstic acid compound, a molybdate compound, a stannic acid compound, and a zirconic acid compound prepared by neutralizing zirconium halide or zirconium oxyhalide with an alkali and removing the solvent. It is possible to provide an electrode containing a composite compound composed of one kind of inorganic compound and water, a solid electrolyte membrane joined with the electrode, and various electrochemical systems using the solid electrolyte membrane. Electrochemical systems include fuel cells, steam pumps, dehumidifiers, air conditioners, electrochromic devices, electrolyzers, electrolyzed hydrogen generators, electrolytic hydrogen peroxide generators, electrolyzed water generators, humidity sensors, hydrogen sensors, primary It can be used for a battery, a secondary battery, an optical switch system, or a new battery system using a polyvalent metal.

Claims (11)

  Neutralize at least one salt of silicic acid, tungstic acid, molybdic acid and stannic acid with an acid in a raw material solution containing an organic compound containing an organic polymer having a hydroxyl group, or a zirconium halide or oxyhalogen From organic compounds and silicic acid compounds, tungstic acid compounds, molybdic acid compounds, stannic acid compounds, zirconic acid compounds and water produced by neutralizing zirconium fluoride with alkali and removing the solvent An electrode comprising a composite compound comprising:   The electrode according to claim 1, wherein the organic polymer having a hydroxyl group is polyvinyl alcohol.   The raw material solution before neutralization contains at least one salt selected from phosphoric acid and boric acid, or at least one selected from aluminum salt, titanium salt, calcium salt, strontium salt, barium salt, and boric acid. The electrode according to claim 1, wherein the composite compound contains at least one of phosphorus, boron, aluminum, titanium, calcium, strontium, and barium compounds.   The electrode according to claim 1, 2 or 3, comprising carbon carrying a metal catalyst as an electrode component.   Neutralize at least one salt of silicic acid, tungstic acid, molybdic acid and stannic acid with an acid in a raw material solution containing an organic compound containing an organic polymer having a hydroxyl group, or a zirconium halide or oxyhalogen From organic compounds and silicic acid compounds, tungstic acid compounds, molybdic acid compounds, stannic acid compounds, zirconic acid compounds and water produced by neutralizing zirconium fluoride with alkali and removing the solvent A solid electrolyte membrane in which an electrode containing a composite compound is bonded to the surface.   The solid electrolyte membrane to which the electrode according to claim 5 is bonded by applying a mixture of the liquid after neutralization in the composite compound preparation process and other electrode components to the surface and bonding by heating.   The mixture of the neutralized solution and other electrode components in the composite compound preparation process is applied in advance on a plane different from the solid electrolyte membrane, and the applied product is transferred to the electrolyte membrane surface by hot pressing. The solid electrolyte membrane which joined the electrode of Claim 5 or 6 apply | coated by the method and joined by heating.   The electrode according to claim 5 or 6, wherein a mixture of the neutralized solution and other electrode components in the composite compound preparation process is applied to the surface of the sheet or film in advance and then transferred to the surface of the electrolyte membrane for transfer. Solid electrolyte membrane.   The solid electrolyte membrane to which the electrode according to claim 8 is joined is a polyester whose main component is a sheet or film.   An electrochemical system using a solid electrolyte membrane, wherein the solid electrolyte membrane according to any one of claims 5 to 9 is used.   The electrochemical system is a fuel cell, a steam pump, a dehumidifier, an air conditioner, an electrochromic device, an electrolyzer, an electrolysis-type hydrogen generator, an electrolytic hydrogen peroxide production device, an electrolyzed water production device, a humidity sensor, a hydrogen sensor, The electrochemical system using a solid electrolyte membrane according to claim 10, which is a new battery system using a primary battery, a secondary battery, an optical switch system or a polyvalent metal.