JP2010238525A - High ion-conductive solid electrolyte and electrochemical system using this solid electrolyte - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide high ion conductive solid electrolyte made of proton (hydrogen ion) or the like, especially at low cost, and showing high conductivity, a fuel cell as well as other electrochemical systems using this solid electrolyte. <P>SOLUTION: The high ion-conductive solid electrolyte, as a basis, comprises at least one or more inorganic compounds selected from silicic acid compound, tungstic acid compound, or zirconic acid compound, and a complex compound containing polyvinyl alcohol, and other constituents than polyvinyl alcohol having sulfonic acid group. Concretely, the structure includes an organic compound having a sulfonic acid group other than polyvinyl alcohol, and the organic compound having the sulfonic acid group is soluble in water. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a high ion conductive solid electrolyte such as proton (hydrogen ion), and is particularly low in price, exhibits high conductivity, and has low swelling when absorbing moisture. The present invention relates to an electrolyte and a fuel cell or other electrochemical system using the solid electrolyte.

Conventionally, as an electrochemical system using a proton conductive solid electrolyte, an electrolytic device such as a fuel cell, a dehumidifier, or an electrolysis-type hydrogen generator has been put into practical use. There are a wide variety. For example, the polymer electrolyte fuel cell has an electrochemical oxidation reaction of hydrogen supplied to the negative electrode as shown in the following formula (1), and an electric current of oxygen supplied to the positive electrode as shown in the formula (2). Electric current flows and electric energy is taken out by a reaction consisting of a chemical reduction reaction and a proton transfer in the electrolyte in the meantime.
H ₂ → 2H ⁺ + 2e ⁻ ………………………… (1)
_1/2 O ₂ + 2H ⁺ 2e ⁻ → H ₂ O (2)

  Some fuel cells use a fuel other than hydrogen, such as a direct methanol fuel cell, where the fuel supplied to the negative electrode is methanol, but in this case as well, the reaction in which the fuel is electrochemically oxidized at the negative electrode to release protons Is carried out in the same way and can be operated using a proton conducting solid electrolyte.

  Electrodes used in fuel cells use a powder catalyst with a large surface area to increase the reaction rate, and further expand the reaction field where substances involved in the reaction such as fuel, water, protons or hydroxide ions meet. In addition, a solid electrolyte is also added to the electrode. That is, the solid electrolyte is used not only by being disposed between the electrodes, but also as an additive to be put into the electrodes.

As an electrolyzer, for example, an electrolysis-type hydrogen generator is put into practical use. 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. Moreover, 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 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 and hydrogen generator. When a voltage is applied between the positive and negative electrodes, 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).

  In addition, various sensors, electrochromic devices, and the like are systems based on the same operating principle as described above, and operate by movement of protons in the electrolyte between two different types of redox pairs of positive and negative electrodes. Therefore, a proton conductive solid electrolyte can be used. Currently, empirical studies of systems using these proton-conducting solid electrolytes are also being conducted.

  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, an electrolyzed water production apparatus and the like can be mentioned as an electrochemical system that operates using a proton conductive solid electrolyte in principle. 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. However, when 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.

  Most of the electrochemical systems that have already been put into practical use, such as the fuel cells, electrolyzers, and dehumidifiers described above, use a perfluorosulfonic acid electrolyte membrane sold under the product name Nafion by DuPont as a solid electrolyte. Yes.

  As another type of solid electrolyte membrane, a solid electrolyte in which a proton conductive compound such as a compound having a sulfonic acid group is introduced into a porous substrate is also disclosed. For example, so-called pore filling electrolyte membranes in which pores of a porous membrane substrate such as polyolefin and polyimide are filled with a proton conductive compound such as a compound having a sulfonic acid group have also been proposed (see Patent Documents 1 to 3). ).

  We also propose an electrolyte membrane made by irradiating a polymer film as a base material with radiation such as gamma rays or electron beams, grafting functional monomers, and chemically converting them to introduce sulfonic acid groups. (See Patent Document 4). Furthermore, an inexpensive polyvinyl alcohol is used as a polymer that becomes a conventional main chain skeleton, and a polymer having an acidic group such as a sulfonic acid group or a carboxyl group is mixed with it, and these are physically or chemically crosslinked. A type of electrolyte has also been proposed (see Patent Document 5). In addition, an inorganic porous material is used as the base material, and a mercapto group is introduced into the surface of the spherical pore by a silane coupling agent, and then oxidized with hydrogen peroxide to give proton conductivity by converting the mercapto group to a sulfonic acid group. Is also disclosed (see Patent Document 6).

  On the other hand, the present inventor is different from an electrolyte composed only of these organic polymers, an inorganic / organic composite compound composed of a silicic acid compound and polyvinyl alcohol (see Patent Document 7), an inorganic composed of a tungstic acid compound or a molybdate compound and polyvinyl alcohol. / Organic composite compound (see Patent Document 8), inorganic / organic composite compound composed of stannic acid compound and polyvinyl alcohol (see Patent Document 9), inorganic / organic composite compound composed of zirconate compound and polyvinyl alcohol (Patent Documents 10 and 11) For example)).

  These inorganic / organic composite compounds can be obtained by a simple and low-cost method of neutralizing silicate, tungstate, molybdate, stannate, zirconium salt or oxyzirconium salt in the presence of polyvinyl alcohol. . In the case of a composite compound in which the inorganic component is a zirconate compound, the zirconium salt or oxyzirconium salt is hydrolyzed by heating in a solution in which polyvinyl alcohol coexists, and then the solvent is removed and then contacted with alkali. (See Patent Document 12).

  Furthermore, the present inventor has disclosed that a sulfonic acid group is introduced into the hydroxyl group position of polyvinyl alcohol in the inorganic / organic composite compound as a method for enhancing proton conductivity (Patent Document 13).

Japanese Patent Application Laid-Open No. 2004-1851973 JP 2006-73235 A JP 2002-083612 A JP 2006-179301 A JP 2007-273203 A JP 2007-311297 A JP 2003-007133 A JP 2003-138084 A JP 2003-208814 A JP 2003-242832 A JP 2004-146208 A Japanese Patent Application No. 2007-84374 JP 2005-353422 A

Electrochemistry, 69, No. 3,154-159 (2001) 2000 Annual Conference of the Institute of Electrical Engineers of Japan, P3373 (2000)

  However, the above-mentioned perfluorosulfonic acid electrolyte membrane has a big problem that it is expensive mainly due to the complexity of the manufacturing process. Although this point is expected to be reduced to some extent by the mass production effect of solid electrolytes, there is a limit to it naturally, and the present situation is that there is a demand for the appearance of inexpensive alternative materials. In order to reduce the price of perfluorosulfonic acid electrolyte membranes, so-called hydrocarbon electrolyte membranes with proton-conducting sulfonic acid groups introduced using hydrocarbon engineering plastics such as polyimide and polyetheretherketone as the main chain skeleton were also developed. However, these hydrocarbon engineering plastics are also not cheap and have little effect of lowering the price.

  These perfluorosulfonic acid electrolyte membranes or hydrocarbon electrolyte membranes are each composed of a single molecule having proton conductivity by having a sulfonic acid group. Since it is necessary to satisfy all functions with one kind of molecule such as strength, chemical stability, and heat resistance, it naturally becomes a limited and expensive material.

  Moreover, since the pore filling membrane as shown in Patent Documents 1 to 3 is separately filled with a compound having proton conductivity such as a compound having a sulfonic acid group in the macro pores of the porous substrate, it is sufficient after filling. If not fixed, a problem arises that the sulfonic acid compound flows out of the solid electrolyte in a wet environment, which is the main use environment of the solid electrolyte. Therefore, various means for fixing such as irradiation of plasma, ultraviolet rays, electron beams, gamma rays, etc. are employed for the polymerization of the fillers or the bonding between the porous substrate and the filler in order to suppress the dropping of the filler compound. However, these methods not only do not allow sufficient fixing, but also increase the manufacturing cost, and it is not possible to reduce the cost.

  A solid electrolyte produced by irradiating a polymer film as a substrate shown in Patent Document 4 with radiation such as gamma rays or electron beams to graft a functional monomer and converting it to a sulfonic acid group is also a substrate. Since a stable organic polymer is selected for the polymer film, it is necessary to irradiate with radiation, and the production cost is increased due to the irradiation with radiation. In addition, solid electrolytes of the type having a main chain skeleton of polyvinyl alcohol shown in Patent Document 5 and cross-linked by a physical or chemical method after introduction of a polymer having an acidic group such as a sulfonic acid group are cross-linked by a polymer having an acidic group. Since it is fixed in a state of being knitted in polyvinyl alcohol, it is not always necessary to fix the sulfonic acid group compound by irradiation. However, polyvinyl alcohol has a sparse molecular structure due to water absorption in a wet environment in which an electrolyte is mainly used, and water-soluble acidic group polymers are likely to fall off the polyvinyl alcohol molecular network gradually. In addition, the polyvinyl alcohol having the main chain skeleton is not thermally and chemically stable as it is, and there is a problem that the use conditions are extremely limited. Further, a solid electrolyte having an inorganic porous material shown in Patent Document 6 as a base material, a mercapto group introduced into the surface of the spherical pore by a silane coupling agent, and oxidized to a sulfonic acid group has a basic skeleton. It is an inorganic porous material, and it is difficult to reduce the thickness due to its hard and brittle nature.

  On the other hand, the solid electrolyte composed of the inorganic / organic composite compounds shown in Patent Documents 7 to 11 provided by the present inventor is water resistant by complexing inexpensive polyvinyl alcohol with an inorganic oxide at a molecular level by a simple method. , Heat resistance and chemical stability can be remarkably improved, and a high-performance solid electrolyte can be obtained despite its low price. Accordingly, solid electrolytes composed of these inorganic / organic composite compounds have a sulfonic acid group on a base material such as a conventional perfluorosulfonic acid based electrolyte membrane made of a single constituent molecule, a so-called hydrocarbon membrane, or a pore filling membrane. It has the potential to solve the problems associated with electrolytes that incorporate compounds.

  However, these inorganic / organic composite compounds also have the following problems to be solved as further problems. Of these inorganic / organic composite compounds, the most preferable as the acid-type proton conductive solid electrolyte is a compound employing a tungstic acid compound as the inorganic compound. Since tungstic acid itself has high proton conductivity, high conductivity can be obtained as a composite compound. However, tungstic acid is not necessarily abundant in terms of resources, and there are concerns about a stable supply because the country of origin is limited. Further, tungstic acid has a slight solubility in water, which may cause a problem when used in a humid environment. In view of these points, there is a problem that the amount of tungstic acid originally responsible for proton conductivity is advantageous as it is contained in a complex compound, but the amount cannot be increased sufficiently, and therefore the proton conductivity is limited. There is a problem that becomes.

  On the other hand, in view of resource abundance, insolubility in water, or price, the most preferable is to employ a silicate compound as an inorganic compound. However, the silicic acid compound itself has poor proton conductivity compared to the tungstic acid compound. In addition, an inorganic compound that employs a zirconate compound is preferable in terms of insolubility in water, but there is a problem in that proton conductivity is poor as compared with a tungstic acid compound as in the case of a silicic acid compound. As a means for introducing a sulfonic acid group into an inorganic / organic composite compound, a means for introducing a sulfonic acid group into a hydroxyl group position of polyvinyl alcohol in the composite compound shown in Patent Document 13 introduces (substitutes) into the hydroxyl position of polyvinyl alcohol. Since the amount of sulfonic acid groups obtained is limited to a small amount, the effect is small.

  Accordingly, the present invention solves the problems of the high ion conductive solid electrolyte and is low in cost and exhibits high conductivity, and a fuel cell using the solid electrolyte. It aims to provide other electrochemical systems.

  In order to achieve the object, the present invention includes at least one or more inorganic compounds selected from silicic acid compounds, tungstic acid compounds or zirconic acid compounds and polyvinyl alcohol, and components other than polyvinyl alcohol have sulfonic acid groups. A high ion conductive solid electrolyte composed of a composite compound is provided as a basis. Specifically, the composite compound includes an organic compound having a sulfonic acid group other than polyvinyl alcohol, the organic compound having a sulfonic acid group is water-soluble, and the organic compound having a sulfonic acid group is polystyrene sulfonic acid. , 2-acrylamide-2-methyl-1-propanesulfonic acid or poly (2-acrylamide-2-methyl-1-propanesulfonic acid) or a derivative thereof.

Further, the content of the organic compound having a sulfonic acid group is 0.01 or more and 1 or less in a weight ratio with respect to the polyvinyl alcohol component in the composite compound, and the composite compound contains the tungstic acid compound and is contained in the tungstic acid compound. The ratio of WO ₃ weight to polyvinyl alcohol weight is 0.3 or less.

  In the raw material solution in which a solvent containing water, silicate or tungstate, and polyvinyl alcohol coexist, the silicate or tungstate is neutralized with an acid and then the solvent is removed. Provided is a structure in which a composite compound is obtained by introducing an organic compound having a sulfonic acid group or a salt thereof into a raw material solution after reconstitution.

  Moreover, the solvent is removed from the raw material solution in which a solvent containing water, zirconium salt or oxyzirconium salt, polyvinyl alcohol, and an organic compound having a sulfonic acid group coexist, and then contacted in the order of alkali and acid. An arrangement for obtaining a compound is provided.

  Further, in a raw material solution in which a water-containing solvent and a zirconium salt or oxyzirconium salt and polyvinyl alcohol coexist, the solvent is removed after neutralizing the zirconium salt or oxyzirconium salt with an alkali, and then contacted with an acid. Provided is a structure for obtaining a composite compound by introducing an organic compound having a sulfonic acid group or a salt thereof into a raw material solution before or after neutralization.

  In addition, a structure in which a sulfonic acid group is bonded to an inorganic compound part, a compound having a mercapto group is bonded to any of the inorganic compound parts in the composite compound, and then the mercapto group is oxidized to be converted into a sulfonic acid group. A structure for obtaining a composite compound in which a sulfonic acid group is bonded to an inorganic compound part, a structure for binding a compound having a mercapto group to an inorganic compound part in the composite compound by reacting a silane coupling agent having a mercapto group with the composite compound, A configuration is provided in which the silane coupling agent is 3-mercaptopropylmethyldimethoxysilane or 3-mercaptopropyltrimethoxysilane.

  An electrochemical system using a high ion conductive solid electrolyte, in which a plurality of electrodes separated by the solid electrolyte are arranged on the high ion conductive solid electrolyte, and the high ion conductive solid electrolyte in the electrode An electrochemical system characterized in that the electrochemical system is a fuel cell, a steam pump, a dehumidifier, an air conditioner, an electrochromic device, an electrolyzer, a humidity sensor, a hydrogen sensor, And an electrolytic apparatus is an electrolysis-type hydrogen generator, an electrolytic hydrogen peroxide production apparatus, and an electrolytic water production apparatus.

  According to the present invention described above, an organic compound having a sulfonic acid group other than polyvinyl alcohol in an inorganic / organic composite compound containing at least one or more inorganic compounds selected from silicic acid compounds, tungstic acid compounds or zirconic acid compounds and polyvinyl alcohol. A sulfonic acid group can be introduced by a simple and low-cost method by containing a compound or by bonding a sulfonic acid group to an inorganic compound part of an inorganic / organic composite compound. It is possible to stably fix the sulfonic acid group. As a result, there are concerns about stable supply due to lack of resources and limited production countries, and even if the amount of tungstic acid compounds that are soluble in water is small or they do not contain tungstic acid compounds. However, an inorganic / organic composite compound having high proton conductivity can be obtained, and a high-performance solid electrolyte having high conductivity at a low price can be obtained.

For example, when a sulfonic acid group is not introduced into the inorganic / organic composite compound and high proton conductivity is provided only by the function of the tungstic acid compound, it is converted to WO ₃ weight as shown in the example of Patent Document 8. The ratio of the tungstic acid compound weight (WO ₃ weight contained in the tungstic acid compound) to the polyvinyl alcohol is desirably 0.36 or more. However, when a sulfonic acid group is introduced as in the present invention, A sufficiently high conductivity can be obtained even at 0.3 or less.

  In the present invention, since an inorganic / organic composite compound is employed, a sulfonic acid group compound can be easily introduced simply by adding a sulfonic acid group compound in the form of a water-soluble polymer to the raw material solution. In addition, in the production process, the sulfonic acid group compound is automatically entangled with the complex compound at the molecular level. Therefore, a compound having a sulfonic acid group can be easily and stably fixed to such an extent that it does not easily fall off due to the contribution of the structural density of the inorganic compound in the composite compound. . Furthermore, in the inorganic / organic composite compound according to the present invention, since the structure of the inorganic compound portion is particularly dense and the degree of freedom for molecular motion is small, the introduced sulfonic acid group polymer is more firmly fixed. .

  In the present invention, the sulfonic acid group compound can be easily and stably fixed to the inorganic portion of the composite compound by introducing a functional group that binds to the inorganic oxide into the organic compound having the sulfonic acid group. The inorganic / organic composite compound according to the present invention contains components of inorganic compounds such as silicic acid compounds, tungstic acid compounds, zirconic acid compounds, and a mercapto group is introduced by firmly bonding a silane coupling agent. be able to. Furthermore, in the case of an inorganic / organic composite compound, unlike an inorganic porous body, it also has the flexibility of an organic polymer and can be easily reduced in thickness.

  In the present invention, as a method for introducing a sulfonic acid group into an inorganic / organic composite compound, an organic compound having a sulfonic acid group is introduced separately from polyvinyl alcohol, so that the sulfonic acid group density can be increased.

  Since the inorganic / organic composite compound into which the compound having a sulfonic acid group is introduced is originally low in price, and the method for introducing the compound having a sulfonic acid group is also low in cost as described above, the solid electrolyte of the present invention is low in price. Can be maintained. In addition, since a compound having a sulfonic acid group has proton conductivity, by introducing it, the conductivity of the complex compound can be increased without increasing the content of tungstic acid that has been responsible for the proton conductivity of the complex compound. The degree of tungstic acid, which is not necessarily abundant in resources and has a limited supply country, is uneasy for stable supply, and is soluble in water, can be reduced.

  The high ion conductive solid electrolyte according to the present invention is proton conductive, and can be used for fuel cells, steam pumps, dehumidifiers, air conditioners, electrochromic devices, various electrolyzers, humidity sensors, hydrogen sensors, and the like. .

1 is a system diagram schematically showing a first embodiment of a manufacturing process of a high ion conductive solid electrolyte according to the present invention. The system figure which shows schematically 2nd Embodiment of the manufacturing process of the high ion conductive solid electrolyte concerning this invention. The system diagram which shows schematically 3rd Embodiment of the manufacturing process of the high ion conductive solid electrolyte concerning this invention.

  Embodiments of a high ion conductive solid electrolyte and an electrochemical system using the solid electrolyte according to the present invention will be described below. The present invention includes at least one inorganic compound selected from a silicic acid compound, a tungstic acid compound, or a zirconic acid compound and polyvinyl alcohol, and a high ionic conductivity comprising a composite compound in which components other than polyvinyl alcohol have sulfonic acid groups. Basic electrolyte.

The complex compound contained in the solid electrolyte in the present invention contains a silicic acid compound, a tungstic acid compound or a zirconic acid compound as an essential component as an essential component. Silicic acid is a compound containing SiO ₂ as a basic unit and containing H ₂ O, and can be represented by the general formula SiO ₂ xH ₂ O. The silicic acid compound in the present invention is silicic acid and its derivatives, Or it shows the whole compound mainly composed of silicic acid. The tungstic acid and WO ₃ as a basic unit, it is a compound which contains H _{2 O,} but those that can be represented by the general formula WO 3 _· xH 2 _O, tungstic acid compound in the present invention, and tungstic acid It refers to all of its derivatives or compounds mainly composed of tungstic acid. Zirconic acid is a compound containing ZrO ₂ as a basic unit and containing H ₂ O, and can be represented by the general formula ZrO ₂ .xH ₂ O. The zirconic acid compound in the present invention refers to zirconic acid. And its derivatives or all compounds mainly composed of zirconic acid.

Therefore, a part of other elements may be substituted as long as the characteristics of silicic acid, tungstic acid and zirconic acid are not impaired, and deviation from the stoichiometric composition or addition of an additive is allowed. For example, salts and hydroxides of silicic acid, tungstic acid, zirconic acid are also based on SiO ₂ , WO ₃ , ZrO ₂ , derivatives based on salts and hydroxides, or compounds based on them Are also included in the silicic acid compound, tungstic acid compound and zirconic acid compound in the present invention.

  The composite compound contained in the solid electrolyte in the present invention contains polyvinyl alcohol as an indispensable component. This 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 part of the hydroxyl group is substituted with another group and those in which another polymer is partially copolymerized can function as polyvinyl alcohol. Moreover, since the same effect is acquired if it passes through polyvinyl alcohol in the reaction process of this invention, the polyvinyl acetate etc. which are the raw materials of polyvinyl alcohol can be used as a starting material.

  As long as the function of the polyvinyl alcohol is sufficiently expressed, other polymers such as polyolefin polymers such as polyethylene and polypropylene, polyacrylic acid polymers, polyether polymers such as polyethylene oxide and polypropylene oxide, polyethylene terephthalate, Polyester polymers such as polybutylene terephthalate, fluorine polymers such as polytetrafluoroethylene and polyvinylidene fluoride, sugar chain polymers such as methylcellulose, polyvinyl acetate polymers, polystyrene polymers, polycarbonate polymers, epoxy resin polymers or Other organic and inorganic additives can also be mixed.

  One or a plurality of inorganic compounds selected from a silicic acid compound, a tungstic acid compound, or a zirconic acid compound and polyvinyl alcohol form an inorganic / organic composite compound. That is, in the composite compound, polyvinyl alcohol and these inorganic compounds are entangled with each other at the molecular level, and both are firmly bonded by hydrogen bonding and dehydration condensation via the hydroxyl group of polyvinyl alcohol. The composite compound is a compound and is distinguished from a mixture obtained by physical mixing of polyvinyl alcohol and an inorganic compound. That is, unlike a mixture, in a compound compound, the chemical properties of each component are not necessarily retained after the compounding. For example, in the case of the present invention, polyvinyl alcohol which is a component of the composite compound is water-soluble (hot water soluble) alone, but one or more inorganic compounds selected from silicic acid compounds, tungstic acid compounds or zirconic acid compounds After the complex compound is formed, it is basically not dissolved in hot water.

In the composite compound, if the amount of the inorganic compound relative to the polyvinyl alcohol is too small, sufficient water resistance, heat resistance, oxidation resistance or strength cannot be obtained. On the other hand, when there are too many inorganic compounds, a softness | flexibility will be impaired and a problem will arise in a brittle point. Therefore, when the inorganic compound in the composite compound is converted into the weight of each basic unit of SiO ₂ , WO ₃ , and ZrO ₂ , the weight ratio of the total weight to the polyvinyl alcohol weight becomes 0.01 to 1. It is preferable to control in such a manner. Moreover, when a composite compound contains a tungstic acid compound, the ratio with respect to the weight of polyvinyl alcohol of ₃ weight of WO contained in a tungstic acid compound can be 0.3 or less. This is because a sufficiently high conductivity can be obtained even when the weight ratio is 0.3 or less. That is, in the present invention, high proton conductivity can be realized even if the amount of tungstic acid compound used is reduced or no tungstic acid compound is contained.

  The composite compound described above as a characteristic configuration of the present invention contains an organic compound having a sulfonic acid group other than polyvinyl alcohol. In this case, the organic compound having a sulfonic acid group may be any as long as it can be fixed in the composite compound. The organic compound having a sulfonic acid group may have a plurality of sulfonic acid groups in the same molecule, or a composite compound may contain a plurality of organic compounds having a sulfonic acid group.

  From the viewpoint of being stably fixed in the composite compound, organic compounds having a sulfonic acid group have a polymer that easily entangles with the composite compound or a functional group that easily binds to an inorganic compound in the composite compound. preferable. In addition, when the organic compound having a sulfonic acid group is a polymer, if the polymer is water-soluble, it can be automatically combined by simply dissolving the polymer in the raw material solution of the composite compound when manufacturing the composite compound. It is advantageous that entanglement with the compound occurs at the molecular level, and as a result, the compound can be stably fixed. Preferred examples include polystyrene sulfonic acid, 2-acrylamide-2-methyl-1-propanesulfonic acid, poly (2-acrylamide-2-methyl-1-propanesulfonic acid), and derivatives thereof.

  If polystyrene sulfonic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid or poly (2-acrylamido-2-methyl-1-propanesulfonic acid) is selected, its content is required to obtain an effect on proton conduction. Is preferably 0.01 or more by weight ratio to the polyvinyl alcohol component in the composite compound. Moreover, since the intensity | strength of a composite compound will become low when there is too much those content, it is preferable that the content is 1 or less by weight ratio with respect to the polyvinyl alcohol component in a composite compound.

  From the viewpoint of stably fixing an organic compound having a sulfonic acid group in a composite compound, the organic compound having a sulfonic acid group is bonded to the inorganic compound portion in the composite compound. It is preferably combined (chemically bonded) with the inorganic compound component in the composite compound. In existing solid electrolytes, the base material is an organic polymer. Therefore, irradiation with plasma, ultraviolet rays, electron beams, gamma rays, or the like is required to fix organic compounds having sulfonic acid groups. However, when an inorganic / organic composite compound is employed as in the present invention, an organic compound having a sulfonic acid group can be bonded to the inorganic compound portion by a relatively simple method. For example, if an organic compound having a sulfonic acid group also has a carboxyl group, it can be bonded to a hydroxyl group on the surface of the inorganic compound by dehydration condensation. Alternatively, when an organic compound having a sulfonic acid group has a cationic group such as an ammonium group, it can be bonded to an anion of an inorganic compound.

  In addition, as a method of bonding an organic compound having a sulfonic acid group to an inorganic compound component, a compound having a mercapto group is bonded to the inorganic compound component in the composite compound, and then the mercapto group is oxidized to be converted into a sulfonic acid group. There is also a method. In this case, a silane coupling agent can be used as the compound having a mercapto group. That is, the silane coupling agent having a mercapto group is hydrolyzed, and the resulting silanol portion and the hydroxyl group on the surface of the inorganic compound in the composite compound are bonded by dehydration condensation. Thereafter, the mercapto group is oxidized with a suitable oxidizing agent and converted to a sulfonic acid group. As the silane coupling agent having a mercapto group, 3-mercaptopropylmethyldimethoxysilane or 3-mercaptopropyltrimethoxysilane is preferably used.

  Hydrolysis of the silane coupling agent can be performed by introducing the silane coupling agent into water or an acetic acid aqueous solution, and the hydrolyzed solution is brought into contact with a solid electrolyte composed of an inorganic / organic composite compound, and the solution is mixed with the composite compound. It can be done by absorbing it inside. As an oxidizing agent for converting a mercapto group into a sulfonic acid group, for example, hydrogen peroxide is used.

  Next, the manufacturing process of the composite compound concerning this invention is demonstrated. FIG. 1 is a system diagram schematically showing a first embodiment of a manufacturing process of a complex compound. First, as a raw material, a solvent containing water is prepared in Step 1, silicate and / or tungstate is prepared in Step 2, polyvinyl alcohol is prepared in Step 3, these raw materials are mixed in Step 4, and water is added. A raw material solution in which silicate and / or tungstate and polyvinyl alcohol coexist is obtained in the solvent to be contained. Any kind of silicate and / or tungstate may be used as long as it dissolves in water, and any kind of cation, ratio of oxygen or cation, and water content may be used. In order to make it possible to efficiently form a solid electrolyte film by blowing off water in the raw material solution within a practical production time range, the raw material solution has a polyvinyl alcohol concentration of 5% by weight or more. More preferably, it is 10% by weight or more.

  Next, in step 5, the silicate and / or tungstate in the raw material solution is neutralized with an acid, and in step 6, a neutralized raw material solution is obtained. At that time, the organic compound having a sulfonic acid group shown in Step 7 or a salt thereof is introduced into the raw material solution shown in Step 4 before neutralization or the raw material solution after neutralization shown in Step 6. Thereafter, the solvent is removed in step 8, and a composite compound that becomes a solid electrolyte is obtained in step 9. The obtained composite compound contains an organic compound having a sulfonic acid group other than polyvinyl alcohol.

  FIG. 2 is a system diagram schematically showing a second embodiment of the production process of the complex compound. First, as a raw material, a solvent containing water in Step 1, a zirconium salt or oxyzirconium salt in Step 2, a polyvinyl alcohol in Step 3, and an organic compound having a sulfonic acid group in Step 4 are prepared. These raw materials are mixed to obtain a raw material solution in which a zirconium salt or oxyzirconium salt, polyvinyl alcohol, and an organic compound having a sulfonic acid group coexist in a solvent containing water. Zirconium salt or oxyzirconium salt may be of any kind as long as it is soluble in water, and any kind of anion, ratio of oxygen or anion, and water content may be used.

  Next, the solvent is removed in Step 6, contacted with an alkali in Step 7, and further contacted with an acid in Step 8 to obtain a composite compound that becomes a solid electrolyte in Step 9. The obtained composite compound contains an organic compound having a sulfonic acid group other than polyvinyl alcohol.

  FIG. 3 is a system diagram schematically showing a third embodiment of the production process of the composite compound. First, as a raw material, a solvent containing water is prepared in Step 1, a zirconium salt or an oxyzirconium salt is prepared in Step 2, polyvinyl alcohol is prepared in Step 3, and these raw materials are mixed in Step 4 to prepare a solvent containing water. A raw material solution in which zirconium salt or oxyzirconium salt and polyvinyl alcohol coexist is obtained. Zirconium salt or oxyzirconium salt may be of any kind as long as it is soluble in water, and any kind of anion, ratio of oxygen or anion, and water content may be used. For example, zirconium halides such as zirconium chloride and zirconium oxyhalides such as zirconium oxychloride are used.

  Next, in step 5, the zirconium salt or oxyzirconium salt in the raw material solution is neutralized with alkali, and in step 6, the neutralized raw material solution is obtained. At that time, the organic compound having a sulfonic acid group or a salt thereof shown in Step 7 is introduced into the raw material solution shown in Step 4 before neutralization or the raw material solution after neutralization shown in Step 6 or the salt thereof. Thereafter, the solvent is removed in step 8 and further contacted with an acid in step 9 to obtain a composite compound that becomes a solid electrolyte in step 10. The obtained composite compound contains an organic compound having a sulfonic acid group other than polyvinyl alcohol.

  In the present invention, a combination of a zirconic acid compound and a silicic acid compound and / or a tungstic acid compound can also be employed as a raw material other than a solvent containing water and polyvinyl alcohol. For example, in the first embodiment, at the time of neutralization with an acid in Step 5, a zirconium salt or an oxyzirconium salt may be included in the acid for neutralization. Moreover, in 2nd Embodiment, when making it contact with the alkali of step 7, what is necessary is just to contain a silicate and / or a tungstate in the alkali made to contact. Furthermore, in 3rd Embodiment, when neutralizing with the alkali of step 5, what is necessary is just to contain a silicate and / or a tungstate in the alkali to neutralize.

  In addition, since the present invention proceeds in a solvent in which water is present, it is sufficient that water is present in the solvent in each of the manufacturing processes described above, and it is not necessary to be a pure water-only solvent. However, water is the most preferable solvent in view of solubility of silicate and / or tungstate, or zirconium salt or oxyzirconium salt, or solubility of polyvinyl alcohol. Therefore, the solvent containing water as a constituent element of the present invention shown in Step 1 may be any solvent that contains water and can coexist with water. As long as there is a minimum amount of water involved in the reaction, the solvent of the present invention can occur even if there is another solvent, so there are an unlimited number of solvents that can coexist with water, and these exist together with water. It may be. That is, the solvent means all components in the raw material solution other than the solute silicate, tungstate, zirconium salt, oxyzirconium salt and polyvinyl alcohol. For example, if sugar is dissolved, it is also a member of the solvent. Therefore, any substance that is recognized as a liquid (including dissolved solids) that can coexist with water can be a solvent.

  In each of the manufacturing processes described above, the type of acid or alkali used for neutralization may be any as long as it can neutralize silicate, tungstate, zirconium salt, or oxyzirconium salt. Phosphoric acid, sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia, calcium hydroxide, strontium hydroxide, barium hydroxide, carbonate, etc. can be used.

  In the second embodiment, the alkali to be contacted after removing the solvent may be any one that can neutralize the zirconium salt or oxyzirconium salt, such as sodium hydroxide, potassium hydroxide, lithium hydroxide, Ammonia, calcium hydroxide, strontium hydroxide, barium hydroxide, carbonate, etc. can be used. These may be used alone or in a mixed state. In addition, as a method of contacting with an alkali, there are a method of immersing in an alkali solution, applying or spraying an alkali solution to a composite compound, or exposing to an alkali vapor.

  In the second embodiment and the third embodiment, the acid to be contacted after removing the solvent may be any acid as long as the sulfonic acid group that has been in the salt form once contacted with the alkali can be changed into the acid form again. It can be used, and hydrochloric acid, sulfuric acid, etc. can be used. In addition, as a method of contacting with an acid, there are a method of immersing in an acid solution, applying or spraying an acid solution to a complex compound, or exposing to an acid vapor.

  The solid electrolyte made of the composite compound produced through the above production process is proton-conductive, so that it has a high conductivity like the conventional perfluorosulfonic acid ion exchange membrane. Can be used as Specifically, a fuel cell, a steam pump, a dehumidifier is formed by arranging a plurality of electrodes separated by a high ion conductive solid electrolyte or by containing a high ion conductive solid electrolyte in the electrode. It can be applied to machines, air conditioners, electrochromic devices, electrolyzers, humidity sensors, hydrogen sensors, electrolysis-type hydrogen generators, electrolytic hydrogen peroxide production devices, and electrolyzed water production devices.

  Specific examples of the high ion conductive solid electrolyte and the electrochemical system using the solid electrolyte according to the present invention will be described below. In addition, this invention is not limited to the content of description of these Examples.

In order to produce an electrolyte membrane of a high ion conductive solid electrolyte according to the present invention, first, tribasic phosphate is added to 100 cc of a 10% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 3,100 to 3,900 and a saponification degree of 86 to 90%. Sodium (Na ₃ PO ₄ · 12H ₂ O) 0.7 g and sodium silicate 4.5 wt% aqueous solution 9 g were added to prepare a raw material solution, and 16 cc of 2.4M hydrochloric acid was added dropwise while stirring the raw material solution. Neutralized. Thereafter, 8 g of an 18% aqueous solution of polystyrene sulfonic acid having a molecular weight of about 75,000 was added and stirring was continued to prepare a viscous raw material solution. This raw material solution is put in a sealed container, defoamed by reducing the pressure with a vacuum pump, and then coated with a blade that can adjust the gap with the base using a micrometer (manufactured by RK Print Coat Instruments Ltd. The film was cast on a polyester film laid on a smooth pedestal of K control coater 202). At this time, the pedestal was heated while being controlled to 80 ° C. After casting the raw material solution on the pedestal, a blade whose gap was adjusted to 0.4 mm was immediately swept over the raw material solution at a constant speed to obtain a constant thickness. When heated at 80 ° C, the water is blown away, and when the fluidity has almost disappeared, the raw material solution is cast again from the top, and the blade with the gap adjusted to 0.4 mm is immediately adjusted at a constant speed. The raw material solution was swept to obtain a constant thickness. Thereafter, the temperature of the pedestal was raised to 135 ° 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, washed twice in hot water at 60 ° C. to 70 ° C. for 30 minutes, and then washed with 1M hydrochloric acid aqueous solution containing 1% by weight of terephthalaldehyde. After performing the operation of immersing for 5 hours and washing in hot water at 60 ° C. to 70 ° C. for 30 minutes twice, the membrane was dried at room temperature to obtain an electrolyte membrane of a high ion conductive solid electrolyte.

To 100 cc of a 10% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 3,100 to 3,900 and a saponification degree of 86 to 90%, 4.5 g of sodium tungstate dihydrate (Na ₂ WO ₄ .2H ₂ O), Then, 0.7 g of trisodium phosphate (Na ₃ PO ₄ · 12H ₂ O) was added to obtain a raw material solution, and 14 cc of 2.4 M hydrochloric acid was added dropwise to neutralize the raw material solution while stirring. Thereafter, 8 g of an 18% aqueous solution of polystyrene sulfonic acid having a molecular weight of about 75,000 was added and stirring was continued to prepare a viscous raw material solution. A film of this raw material solution was formed in the same manner as in Example 1 below.

To 100 cc of a 10% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 3,100 to 3,900 and a saponification degree of 86 to 90%, 4.5 g of sodium tungstate dihydrate (Na ₂ WO ₄ .2H ₂ O), 0.7 g of trisodium phosphate (Na ₃ PO ₄ · 12H ₂ O) and 8 g of a sodium silicate 4.5 wt% aqueous solution were added to form a raw material solution. Neutralized by adding dropwise. Thereafter, 8 g of an 18% aqueous solution of polystyrene sulfonic acid having a molecular weight of about 75,000 was added and stirring was continued to prepare a viscous raw material solution. A film of this raw material solution was formed in the same manner as in Example 1 below.

1 g of polystyrene sulfonate sodium salt having a molecular weight of about 1,000,000 is added to 100 cc of a 10% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 3,100-3,900 and a saponification degree of 86-90%, and sodium tungstate dihydrate. Add 4.5 g of Japanese (Na ₂ WO ₄ · 2H ₂ O), 0.7 g of trisodium phosphate (Na ₃ PO ₄ · 12H ₂ O), and 8 g of 4.5% sodium silicate aqueous solution to make a raw material solution. While stirring this raw material solution, 18 cc of 2.4M concentration hydrochloric acid was added dropwise to neutralize it to prepare a viscous raw material solution. A film of this raw material solution was formed in the same manner as in Example 1 below. In addition, the polystyrene sulfonic acid sodium salt is modified to polystyrene sulfonic acid having a sulfonic acid group in the neutralization step during film formation and the operation of immersing the film in a hydrochloric acid solution containing terephthalaldehyde.

Poly (styrene sulfonic acid-maleic acid) copolymer sodium salt having a molecular weight of about 20,000 in 100 cc of a 10% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 3,100-3,900 and a saponification degree of 86-90% ( 4 g of 25% by weight aqueous solution of styrene sulfonic acid and maleic acid in a molar ratio of 3: 1), sodium tungstate dihydrate (Na ₂ WO ₄ .2H ₂ O) 4.5 g, trisodium phosphate (Na ₃ PO) ₍₄ · 12H ₂ O) 0.7 g and sodium silicate 4.5% by weight aqueous solution 8 g were added to prepare a raw material solution. While stirring this raw material solution, 18 cc of 2.4 M hydrochloric acid was added dropwise to neutralize the solution. A thick raw material solution was prepared. A film of this raw material solution was formed in the same manner as in Example 1 below. Poly (styrenesulfonic acid-maleic acid) copolymer sodium salt is a poly (styrenesulfonic acid) having a sulfonic acid group in the neutralization step during film formation and the operation of immersing the film in a hydrochloric acid solution containing terephthalaldehyde. -Maleic acid) copolymer.

To 100 cc of a 10% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 3,100 to 3,900 and a saponification degree of 86 to 90%, 4.5 g of sodium tungstate dihydrate (Na ₂ WO ₄ .2H ₂ O), 0.7 g of trisodium phosphate (Na ₃ PO ₄ · 12H ₂ O) and 8 g of a sodium silicate 4.5 wt% aqueous solution were added to form a raw material solution. Neutralized by adding dropwise. Thereafter, 1 g of 2-acrylamido-2-methyl-1-propanesulfonic acid was added and stirring was continued to prepare a viscous raw material solution. A film of this raw material solution was formed in the same manner as in Example 1 below.

To 100 cc of a 10% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 3,100 to 3,900 and a saponification degree of 86 to 90%, 4.5 g of sodium tungstate dihydrate (Na ₂ WO ₄ .2H ₂ O), 0.7 g of trisodium phosphate (Na ₃ PO ₄ · 12H ₂ O) and 8 g of a sodium silicate 4.5 wt% aqueous solution were added to form a raw material solution. Neutralized by adding dropwise. Thereafter, 3 g of a 15% aqueous solution of poly (2-acrylamido-2-methyl-1-propanesulfonic acid) having a molecular weight of about 2,000,000 was added and stirring was continued to prepare a viscous raw material solution. A film of this raw material solution was formed in the same manner as in Example 1 below.

In order to produce an electrolyte membrane of a high ion conductive solid electrolyte according to the present invention, first, zirconium oxychloride octahydrate is added to 50 cc of a 10% by weight aqueous solution of polyvinyl alcohol having a molecular weight of 146,000 to 186,000 and a saponification degree of about 99%. 3 g of the product (ZrCl ₂ O · 8H ₂ O) and 4 g of an 18% aqueous solution of polystyrenesulfonic acid having a molecular weight of about 75,000 were mixed and heated at 50 ° C. for 1 hour with stirring to obtain a raw material solution. After defoaming this raw material solution, it is laid on a smooth pedestal of a coating device (K Control Coater 202 manufactured by RK Print Coat Instruments Ltd.) equipped with a blade that can adjust the gap with the pedestal using a micrometer. The film was cast on a polyester film. At this time, the pedestal was heated while being controlled to be 50 ° C to 60 ° C. After casting the raw material solution on the pedestal, a blade whose gap was adjusted to 0.4 mm was immediately swept over the raw material solution at a constant speed to obtain a constant thickness. A blade that is heated while being heated at 50 ° C. to 60 ° C. to remove moisture, and when the fluidity has almost disappeared, the raw material solution is cast again from above, and the gap is immediately adjusted to 0.4 mm again. Was swept over the raw material solution at a constant speed to obtain a constant thickness. Thereafter, the temperature of the pedestal was raised to 125 ° C. to 130 ° 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, immersed in an aqueous 1.67% by weight ammonia solution at room temperature for 2 hours, and then washed twice in hot water at 60 ° C. to 70 ° C. for 30 minutes. Further, after being immersed in a 1.8 M sulfuric acid aqueous solution for 2 hours at room temperature and washed twice in hot water at 60 ° C. to 70 ° C. for 30 minutes, it was dried at room temperature to obtain a high ion conductive solid electrolyte. An electrolyte membrane was obtained.

In order to produce an electrolyte membrane of a high ion conductive solid electrolyte according to the present invention, first, zirconium oxychloride octahydrate is added to 50 cc of a 10% by weight aqueous solution of polyvinyl alcohol having a molecular weight of 146,000 to 186,000 and a saponification degree of about 99%. 3 g of the product (ZrCl ₂ O.8H ₂ O) and 0.5 g of 2-acrylamido-2-methyl-1-propanesulfonic acid were added and heated at 50 ° C. for 1 hour with stirring to obtain a raw material solution. This raw material solution was formed into a film in the same manner as in Example 8 below.

100 g of a 10% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 3,100-3,900 and a saponification degree of 86-90%, 0.7 g of trisodium phosphate (Na ₃ PO ₄ · 12H ₂ O), and sodium silicate 4 9 g of a 0.5 wt% aqueous solution was added to form a raw material solution, and 16 cc of 2.4M hydrochloric acid was added dropwise to neutralize the raw material solution while stirring to prepare a viscous raw material solution. A film of this raw material solution was formed in the same manner as in Example 1 below. A silane coupling agent, 3-mercaptopropylmethyldimethoxysilane (KBM-802 manufactured by Shin-Etsu Chemical Co., Ltd.) (1.2 g) was added to 40 cc of water and stirred well, and the above electrolyte membrane was immersed therein at room temperature. After soaking for 3 hours, heat in an oven at 110 ° C. for 1 hour and wash in hot water at 60 ° C. to 70 ° C. for 30 minutes twice, then oxidize mercapto groups to sulfonic acid groups. Therefore, it was immersed in 3% hydrogen peroxide water at 40 ° C. to 50 ° C. for 2 hours. An operation of washing in hot water at 60 ° C. to 70 ° C. for 30 minutes twice, then immersing in 1.2 M hydrochloric acid for 2 hours, and washing in hot water at 60 ° C. to 70 ° C. for 30 minutes. Performed twice and dried at room temperature.

  Add 1.2 g of mercaptopropyltrimethoxysilane (KBM-803, Shin-Etsu Chemical Co., Ltd.), a silane coupling agent, to 40 cc of water, stir well, and immerse the same electrolyte membrane in Example 10 at room temperature. The same operation as in Example 10 was performed.

[Comparative Example 1] → Corresponding to Examples 1, 10 and 11 Trisodium phosphate (Na ₃₎ was added to 100 cc of a 10% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 3,100 to 3,900 and a saponification degree of 86 to 90%. PO ₄ · 12H ₂ O) 0.7 g and sodium silicate 4.5 wt% aqueous solution 9 g were added to make a raw material solution, and while stirring this raw material solution, 16 cc of 2.4M concentration hydrochloric acid was added dropwise to neutralize, A viscous raw material solution was prepared. A film of this raw material solution was formed in the same manner as in Example 1 below.

[Comparative Example 2] → Corresponding to Example 2 Sodium tungstate dihydrate (Na ₂₎ was added to 100 cc of a 10% by weight aqueous solution of polyvinyl alcohol having a polymerization degree of 3,100 to 3,900 and a saponification degree of 86 to 90%. _{WO 4 · 2H 2 O) 4.5g} , and trisodium phosphate _{(added Na 3 PO 4 · 12H 2 O} ) 0.7g a raw material solution, a hydrochloric acid 2.4M concentration while stirring the raw material solution 14 cc was dropped and neutralized to prepare a viscous raw material solution. A film of this raw material solution was formed in the same manner as in Example 1 below.

[Comparative Example 3] → Corresponding to Examples 3 to 7 To 100 cc of a 10 wt% aqueous solution of polyvinyl alcohol having a polymerization degree of 3,100 to 3,900 and a saponification degree of 86 to 90%, sodium tungstate dihydrate ( 3 g of Na ₂ WO ₄ · 2H ₂ O), 0.7 g of trisodium phosphate (Na ₃ PO ₄ · 12H ₂ O), and 8 g of sodium silicate 4.5 wt% aqueous solution are added to form a raw material solution. While stirring, 16 cc of 2.4M hydrochloric acid was added dropwise to neutralize the solution to prepare a viscous raw material solution. A film of this raw material solution was formed in the same manner as in Example 1 below.

[Comparative Example 4] → Corresponding to Examples 8 and 9 In order to produce an electrolyte membrane of a high ion conductive solid electrolyte according to the present invention, first, polyvinyl having a molecular weight of 146,000 to 186,000 and a saponification degree of about 99% 3 g of zirconium oxychloride octahydrate (ZrCl ₂ O.8H ₂ O) was mixed with 50 cc of an alcohol 10 wt% aqueous solution and heated at 50 ° C. for 1 hour with stirring to obtain a raw material solution. This raw material solution was formed into a film in the same manner as in Example 8 below.

  The ion conductivity of the produced solid electrolyte was measured by the following method. First, the solid electrolyte membrane was cut into a strip shape having a width of 15 mm and a length of 35 mm, and two platinum plates having a width of 10 mm were placed at both ends of the electrolyte membrane, and sandwiched between polytetrafluoroethylene jigs. The polytetrafluoroethylene jig has a square window with a side of 15 mm in the middle so that the electrolyte membrane can always come into contact with the external environment. An AC voltage of 10 mV was applied to the platinum plate while changing the frequency from 50 Hz to 5 MHz using an LCR meter, and the response of current and phase angle was measured. The ionic conductivity was determined from the Cole-Cole plot as is generally done. This measurement was performed in a state where the solid electrolyte was immersed in pure water, and was performed while controlling the temperature at 60 ° C. in a thermostatic bath. The measurement was performed about 30 minutes after being immersed in pure water.

  As shown in Examples 1 to 9, a composite compound composed of a silicic acid compound, a tungstic acid compound, a zirconic acid compound and polyvinyl alcohol has a sulfonic acid group by containing an organic compound having a sulfonic acid group in any case. The conductivity is higher than those not containing the organic compound (Comparative Examples 1 to 4). From this, it can be seen that high conductivity can be realized when the composite compound contains an organic compound having a sulfonic acid group other than polyvinyl alcohol.

As shown in Comparative Examples 2 and 3, even in the case of a composite compound containing tungstic acid having proton conductivity, if the tungstic acid compound content in terms of WO ₃ is only 0.3 by weight ratio to polyvinyl alcohol, the conductivity is too high. The degree is not obtained. However, as in Examples 2 to 7, polystyrene sulfonic acid or its derivative poly (styrene sulfonic acid-maleic acid) copolymer, 2-acrylamide-2-methyl-1-propanesulfonic acid or poly (2-acrylamide) By adding (-2-methyl-1-propanesulfonic acid), high conductivity can be obtained even if the amount of tungstic acid compound is small. This effect makes it possible to keep the content of the tungstic acid compound, which is not necessarily abundant in terms of resources and has a concern about stable supply because the country of production is limited, and also has solubility in water, to a small amount.

  Furthermore, as shown in Examples 1, 8 and 9, even in the case of a silicic acid compound-based compound or a zirconic acid compound-based composite compound which does not contain any tungstic acid having a proton conduction function, an organic compound having a sulfonic acid group is used. By containing, a considerably high conductivity can be obtained. As shown in Examples 1 to 9, the introduction of an organic compound having a sulfonic acid group can be performed simply by adding these compounds to the raw material solution, and the operation is extremely simple. Each of the electrolyte membranes of Examples 1 to 9 has undergone a process of repeatedly washing in hot water at the time of manufacture, and the conductivity measurement is also high despite being immersed in water at 60 ° C. for 30 minutes. The obtained conductivity indicates that organic compounds having a sulfonic acid group do not flow out into water and are firmly fixed in these composite compounds. The reason why organic compounds with sulfonic acid groups can be stably fixed with a simple operation just by mixing them into the raw material solution is because they employ inorganic / organic composite compounds and make good use of their composite processes. is there.

  Examples 10 and 11 in which an organic compound having a sulfonic acid group was introduced using a silane coupling agent also showed higher proton conductivity than Comparative Example 1 in which an organic compound having a sulfonic acid group was not introduced, which was completely tungsten. Although it does not contain an acid compound, it exhibits a conductivity equal to or higher than those of Comparative Examples 2 and 3 containing a tungstic acid compound. A silane coupling agent generates a silanol group by a hydrolysis reaction, and silanol is a substance of the same kind as a silicic acid compound which is an inorganic component in a composite compound, and forms a stable bond. That is, by employing an inorganic / organic composite compound containing such an inorganic compound, an organic compound having a sulfonic acid group can be stably fixed. In addition, since the inorganic / organic composite compound is employed, it is more flexible than a conventional porous body made only of an inorganic compound, and it is difficult to break even when processed into a thin film.

  According to the present invention described above, an organic compound having a sulfonic acid group other than polyvinyl alcohol in an inorganic / organic composite compound containing at least one or more inorganic compounds selected from silicic acid compounds, tungstic acid compounds or zirconic acid compounds and polyvinyl alcohol. A sulfonic acid group can be introduced by a simple and low-cost method by containing a compound or by bonding a sulfonic acid group to an inorganic compound part of an inorganic / organic composite compound. It is possible to stably fix the sulfonic acid group. As a result, there are concerns about stable supply due to lack of resources and limited production countries, and even if the amount of tungstic acid compounds that are soluble in water is small or they do not contain tungstic acid compounds. However, an inorganic / organic composite compound having high proton conductivity can be obtained, and a high-performance solid electrolyte having high conductivity at a low price can be obtained. A fuel cell or other electrochemical system can be obtained using the high ion conductive solid electrolyte.

Claims (17)

  A high ion comprising at least one inorganic compound selected from a silicic acid compound, a tungstic acid compound, or a zirconic acid compound and polyvinyl alcohol, and a component other than polyvinyl alcohol is a composite compound having a sulfonic acid group Conductive solid electrolyte.   The high ion conductive solid electrolyte according to claim 1, wherein the composite compound contains an organic compound having a sulfonic acid group other than polyvinyl alcohol.   The high ion conductive solid electrolyte according to claim 2, wherein the organic compound having a sulfonic acid group is water-soluble.   The organic compound having a sulfonic acid group is polystyrene sulfonic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid, poly (2-acrylamide-2-methyl-1-propanesulfonic acid) or a derivative thereof. Item 4. The high ion conductive solid electrolyte according to Item 2 or 3.   The high ion conductive solid electrolyte according to claim 2, 3 or 4, wherein the content of the organic compound having a sulfonic acid group is 0.01 or more and 1 or less in a weight ratio with respect to the polyvinyl alcohol component in the composite compound. 6. The high ion conductivity according to claim 1, 2, 3, 4 or 5, wherein the composite compound contains a tungstic acid compound, and the ratio of the weight of WO ₃ contained in the tungstic acid compound to the weight of polyvinyl alcohol is 0.3 or less. Solid electrolyte.   In a raw material solution in which a solvent containing water, a silicate or tungstate, and polyvinyl alcohol coexist, the solvent is removed after neutralizing the silicate or tungstate with an acid, and before or after neutralization 7. The high ion conductive solid electrolyte according to claim 1, wherein a composite compound is obtained by introducing an organic compound having a sulfonic acid group or a salt thereof into the raw material solution.   The solvent is removed from the raw material solution in which a solvent containing water, a zirconium salt or an oxyzirconium salt, polyvinyl alcohol, and an organic compound having a sulfonic acid group coexist, and then contacted in the order of alkali and acid. The high ion conductive solid electrolyte according to claim 1, 2, 3, 4 or 5.   In a raw material solution in which a water-containing solvent and a zirconium salt or oxyzirconium salt and polyvinyl alcohol coexist, after neutralizing the zirconium salt or oxyzirconium salt with an alkali, the solvent is removed, and then the acid is contacted and neutralized. The high ion conductive solid electrolyte according to claim 1, 2, 3, 4 or 5, wherein a composite compound is obtained by introducing an organic compound having a sulfonic acid group or a salt thereof into a raw material solution before or after neutralization.   The high ion conductive solid electrolyte according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, wherein a sulfonic acid group is bonded to the inorganic compound part.   A compound having a sulfonic acid group bonded to an inorganic compound part is obtained by binding a compound having a mercapto group to any one of the inorganic compound parts in the composite compound, and then oxidizing the mercapto group into a sulfonic acid group. 10. The high ion conductive solid electrolyte according to 10.   The high ion conductive solid electrolyte according to claim 11, wherein a compound having a mercapto group is bonded to an inorganic compound part in the composite compound by reacting a silane coupling agent having a mercapto group with the composite compound.   The high ion conductive solid electrolyte according to claim 12, wherein the silane coupling agent is 3-mercaptopropylmethyldimethoxysilane or 3-mercaptopropyltrimethoxysilane.   Electricity using a high ion conductive solid electrolyte, characterized in that the high ion conductive solid electrolyte according to any one of claims 1 to 13 is provided with a plurality of electrodes separated by the solid electrolyte. Chemical system.   An electrochemical system using a high ion conductive solid electrolyte, wherein the high ion conductive solid electrolyte according to claim 1 is contained in an electrode.   The electrochemical system using a high ion conductive solid electrolyte according to claim 15, wherein the electrochemical system is a fuel cell, a steam pump, a dehumidifier, an air conditioner, an electrochromic device, an electrolyzer, a humidity sensor, or a hydrogen sensor.   The electrochemical system using a high ion conductive solid electrolyte according to claim 16, wherein the electrolysis apparatus is an electrolysis-type hydrogen generator, an electrolytic hydrogen peroxide production apparatus, or an electrolyzed water production apparatus.

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