JP5229931B2 - PROTON CONDUCTIVE COMPOSITE ELECTROLYTE MEMBRANE AND METHOD FOR PRODUCING THE SAME - Google Patents

Description

  The present invention relates to a proton conductive composite electrolyte membrane, a method for producing the same, an energy device using the proton conductive composite electrolyte membrane, and a fuel cell, and more specifically, when the electrolyte material is an ionic liquid alone. The present invention relates to a proton conductive composite electrolyte membrane capable of improving ionic conductivity, a manufacturing method thereof, an energy device using the proton conductive composite electrolyte membrane, and a fuel cell.

Fuel cells have high power generation efficiency and excellent environmental load control, and are expected to contribute to solving environmental and energy problems that are currently a major issue in countries that consume large amounts of energy. It is a generational energy supply device.
Fuel cells are classified according to the type of electrolyte. Among them, polymer electrolyte fuel cells are small and can provide high output, so that they can be used for small-sized stationary devices, mobile devices, and portable terminals. Research and development is underway for the application of energy as a source of energy.

  Such a solid polymer electrolyte membrane is a solid polymer material having a hydrophilic functional group such as a sulfonic acid group or a phosphoric acid group in a polymer chain, and is firmly bonded to a specific ion, and is either a cation or an anion. Since it has a property of selectively permeating ions, it is formed into particles, fibers or membranes and used in various applications such as electrodialysis, diffusion dialysis, and battery membranes.

  In addition, solid polymer fuel cells are being actively improved as a power generation means that can provide high overall energy efficiency. The main components are anode and cathode electrodes, a separator plate that forms a gas flow path, and a solid polymer electrolyte membrane that separates the electrodes. Protons generated on the anode catalyst move through the solid polymer electrolyte membrane, reach the cathode catalyst, and react with oxygen. Therefore, the ion conduction resistance between the two electrodes greatly affects the battery performance.

In order to form a fuel cell using the above-mentioned solid polymer electrolyte membrane, it is necessary to join the catalyst of both electrodes and the solid polymer electrolyte membrane by an ion conduction path. For this purpose, a catalyst layer in which a polymer electrolyte solution and catalyst particles are mixed, applied and dried to bond them together is used as an electrode, and the electrode catalyst and the solid polymer electrolyte membrane are pressed under heating. The technique was commonly used.
In general, a polymer in which a sulfonic acid group is introduced into a perfluorocarbon-based main chain is used as a polymer electrolyte responsible for ionic conduction. As specific products, Nafion manufactured by DuPont, Flemion manufactured by Asahi Glass Co., Ltd., Aciplex manufactured by Asahi Kasei Co., Ltd., and the like are used. A perfluorosulfonic acid polymer electrolyte is composed of a perfluorocarbon main chain and a side chain having a sulfonic acid group, and the polymer electrolyte is a region mainly composed of a sulfonic acid group and a region mainly composed of a perfluorocarbon main chain. It is thought that the sulfonic acid group phase forms a cluster by microphase separation. The site where the perfluorocarbon main chain aggregates contributes to the chemical stability of the perfluorosulfonic acid electrolyte membrane, and the sulfonic acid groups gather to form a cluster that contributes to ionic conduction. Part.

  As described above, it is difficult to produce a perfluorosulfonic acid electrolyte membrane having both excellent chemical stability and ion conductivity, and there is a drawback that it is very expensive. Therefore, the use of perfluorosulfonic acid is limited, and it is extremely difficult to apply it to a polymer electrolyte fuel cell which is expected to be a power source for a moving body.

  In addition, current polymer electrolyte fuel cells are operated in a relatively low temperature range from room temperature to about 80 ° C. The limitation on the operating temperature is that the fluorine-based membrane used has a glass transition point in the vicinity of 120 to 130 ° C., and it becomes difficult to maintain an ion channel structure that contributes to proton conduction in a higher temperature region. Therefore, it is substantially desirable to use at 100 ° C. or lower, and since water is used as a proton conducting medium, pressurization is required when the water boiling point exceeds 100 ° C., and the apparatus becomes large. . The low operating temperature results in low power generation efficiency for the fuel cell and significant poisoning of the catalyst by CO. When the operating temperature is 100 ° C. or higher, the power generation efficiency is improved, and the waste heat can be used. Also, considering the application to fuel cell vehicles, if the operating temperature can be raised to 120 ° C, not only the efficiency will be improved, but also the radiator load required for exhaust heat will be lowered, and it will be used in current mobile units. The same specifications as the existing radiator can be applied, so the system can be made compact.

  Thus, various studies have been made so far in order to realize operation at higher temperatures. Typically, as an action with a view to reducing the cost of the previous electrolyte membrane, instead of a fluorine membrane, application of an aromatic hydrocarbon polymer material that is inexpensive and excellent in heat resistance to a solid polymer electrolyte Is being considered. For example, various aromatic hydrocarbon solid polymer electrolytes such as sulfonated polyetheretherketone, sulfonated polyethersulfone, sulfonated polyetherethersulfone, sulfonated polysulfide, and polybenzimidazole are studied as solid polymer electrolytes. Has been.

However, since the polymer electrolyte also uses water as a proton conduction medium, pressurization is required when the boiling point of water exceeds 100 ° C., which makes the apparatus large. Furthermore, as an electrolyte that has high heat resistance and does not use water as a proton conducting medium, “a cation-conductive / proton-conducting ceramic membrane infiltrated with an ionic liquid” has been proposed (see, for example, Patent Document 1).
This electrolyte membrane is obtained by modifying so as to exhibit ionic conductivity on the basis of a porous and flexible ceramic membrane described in Patent Document 2, and then treating with an ionic liquid.
Further, this electrolyte membrane has extremely good proton conductivity or cation conductivity at a temperature higher than 100 ° C. by using an ionic liquid. Furthermore, flexibility is maintained and it can be used as an electrolyte membrane of a fuel cell.
JP-T-2004-515351 PCT / EP98 / 05939

  However, an electrolyte membrane in which the above-described ceramic membrane and ionic liquid are combined impregnates the ionic liquid into a ceramic membrane having no ionic conductivity, so that the ionic conductivity is lower than that of the ionic liquid alone.

  The present invention has been made in view of such problems of the prior art, and the object of the present invention is to improve ionic conductivity, heat resistance and water content compared to when the ionic liquid is used alone. An object of the present invention is to provide a proton conductive composite electrolyte membrane that can suppress swelling at the time and can be manufactured at low cost, a manufacturing method thereof, an energy device using the proton conductive composite electrolyte membrane, and a fuel cell.

  As a result of intensive studies to solve the above problems, the present inventors chemically modified the surface in the spherical pores of the inorganic porous body with a proton-donating functional group and impregnated with a specific ionic liquid, thereby The present inventors have found that the problem can be solved and have completed the present invention.

That is, the proton conductive composite type electrolyte membrane of the present invention is a proton conductive composite type electrolyte membrane formed by disposing an electrolyte material in a plurality of spherical holes of an inorganic porous body,
The inorganic porous body has spherical holes that exist three-dimensionally in the inorganic porous body, and the spherical holes communicate with each other.
The inorganic porous body has a porosity of 70 to 90%,
The inorganic porous body is formed of at least one metal oxide selected from the group consisting of alumina, silica, titania and zirconia,
The inorganic porous body has a sulfonic acid group on the surface in the spherical hole,
The electrolyte material includes 1-ethyl-3-methylimidazolium hydrogen sulfate which is an ionic liquid.

The first method for producing a proton conductive composite electrolyte membrane according to the present invention includes the following step (1): mixing an inorganic sol and a spherical organic resin in a solvent in the next step (1). (2) A step of stirring the suspension and forming a film by filtration (3) A step of removing excess moisture from the filtration molded membrane and drying (4) A filter molded membrane is heated and fired Step of forming porous membrane (5) Chemical modification step of introducing a proton donating functional group into the spherical pore of the porous membrane (6) Step of fixing the introduced functional group into the spherical pore to form an inorganic porous body (7) A method for producing a proton-conductive composite electrolyte membrane, which comprises a step of impregnating an electrolyte material into the obtained inorganic porous body ,
In the above step (5), a hydroxyl group is added to the surface in the spherical pores of the inorganic porous body by a hydrothermal reaction or a hydroxyl group existing on the surface is increased by a hydrothermal reaction, and a mercapto group is further introduced by a silane coupling agent. Thereafter, the mercapto group is oxidized in an aqueous hydrogen peroxide solution to introduce a sulfonic acid group .
Furthermore, the second method for producing a proton conductive composite electrolyte membrane according to the present invention includes the following steps in producing the proton conductive composite electrolyte membrane:
(1) Step of mixing an inorganic sol and a spherical organic resin in a solvent to form a suspension
(2) Stirring the suspension and forming a film by filtration
(3) Step of removing excess moisture from the filtration molded membrane and drying it
(4) Step of heating and baking the filtration molded membrane to form a porous membrane
(5) Chemical modification step for introducing a proton-donating functional group into the spherical pores of the porous membrane
(6) Step of fixing the introduced functional group in the spherical pores to form an inorganic porous material
(7) A step of impregnating the obtained inorganic porous material with an electrolyte material
A method for producing a proton conductive composite electrolyte membrane, comprising:
In the step (5), a hydroxyl group is added to the surface in the spherical pores of the inorganic porous body by a hydrothermal reaction or the hydroxyl group present on the surface is increased by a hydrothermal reaction, and further in 1,3-propane sultone and toluene solution It is characterized by introducing a sulfonic acid group by reacting with.

  Furthermore, the energy device and the fuel cell of the present invention are characterized by applying the proton conductive composite electrolyte membrane.

  According to the present invention, the surface in the spherical pores of the inorganic porous body is chemically modified with a proton-donating functional group and impregnated with a specific ionic liquid, so that the ionic conductivity is higher than when the ionic liquid alone is used. It is improved, heat resistance is high, swelling when containing water can be suppressed, and it can be manufactured at low cost.

  Hereinafter, the proton conductive composite electrolyte membrane of the present invention will be described in detail. In the present specification, “%” indicates a mass percentage unless otherwise specified.

The proton conductive composite electrolyte membrane of the present invention is formed by disposing an electrolyte material in a plurality of spherical holes of an inorganic porous material.
The inorganic porous body has a proton-donating functional group on the surface in the spherical pore. The electrolyte material contains a cation and a polyvalent anion, and is disposed (filled) in the spherical hole so as to exhibit proton conductivity.
FIG. 1 shows a schematic structure and a photograph of the present electrolyte membrane (inorganic porous body 1 and electrolyte material 2) sandwiched between electrode materials 3.

In this way, by impregnating an electrolyte material containing a cation and a polyvalent anion into an inorganic porous material whose surface is chemically modified with proton-donating functional groups, it is fixed due to the interaction effect acting on the interface. The ion conductivity of the ionized ion conductor is higher than that of the liquid state.
Also, immobilization of the electrolyte material and improvement of ionic conductivity can be achieved at once.
Furthermore, since it is made of a material cheaper than the fluorine-based electrolyte, an electrolyte membrane that is cheaper and suitable for popularization can be obtained.

Furthermore, since an inorganic porous body is used as a holding body and an electrolyte material having excellent heat resistance can be disposed inside, an electrolyte membrane having excellent heat resistance can be obtained.
In the wet state, the inorganic porous body suppresses the swelling of the electrolyte material. In particular, since the porous body receives a uniform and dispersed swelling force with respect to the swelling of the electrolyte material when it contains water by configuring the spherical pores existing in the porous body with a substantially uniform diameter, the local electrolyte The damage of the is suppressed. In other words, since the spherical pores of the inorganic porous body have a three-dimensional regular array structure, the swelling pressure of the electrolyte material is uniformly applied to the inorganic porous body, and therefore, it is suitable as a support for the electrolyte membrane that swells with water.
Furthermore, by controlling the spherical pores of the porous body almost evenly, the impregnation state of the electrolyte material becomes better, compared to the case where the perfluorosulfonic acid electrolyte material used conventionally is applied to the same composite electrolyte membrane High proton conductivity.

  Here, the electrolyte material containing the cation and the polyvalent anion is: 1. Excellent thermal stability (non-volatile, extremely low vapor pressure, liquid in a wide temperature range) 2. high ion density; From the viewpoint of a large heat capacity and the like, it is preferable to use an ionic liquid.

Exemplary ionic liquids, the cation, for example, etc. imidazolium derivative (imidazolium Derivatives, 2 location recombinants) can be mentioned as shown in the following chemical formula 2.

R1 and R2 in Chemical Formula 2 may be the same or different, and have a monovalent organic group, preferably a monovalent hydrocarbon group, and more preferably an alkyl group or arylalkyl group having 1 to 20 carbon atoms.
Specific examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, hexadecyl, dodecyl, tetradecyl, hexadecyl, octadecyl, benzyl, γ -A phenyl propyl group etc. can be mentioned.

Further, the multivalent anion, _{S O} ^{4 2 -} can be used. At this time, high proton conductivity is obtained with respect to other ionic liquids.

  These cations or polyvalent anions can be used alone or in combination of two or more.

On the other hand, from the viewpoint of stably holding the electrolyte material, the inorganic porous body is, for example, alumina (Al ₂ O ₃ ), silica (SiO ₂ ), titania (TiO ₂ ), zirconia (ZrO ₂ ), and these It is preferable to include those related to any combination.
Since there are many metal oxides that are stable and available at low cost, it is possible to obtain an optimum electrolyte membrane at a lower cost by appropriately selecting them.

Further, the inorganic porous body has spherical holes having a substantially uniform inner diameter, the spherical holes are three-dimensionally present inside the porous body, and adjacent spherical holes are in communication with each other. It is preferable to have an electrolyte material.
At this time, since the spherical pores are regularly and three-dimensionally arranged in the inorganic porous body, the impregnation state of the electrolyte material can be controlled by changing the size of the spherical pores.

  Furthermore, the porosity of the inorganic porous material is preferably 70 to 90%. At this time, the filling rate of the electrolyte material into the inorganic porous body can be increased, and high ion conductivity can be obtained.

Furthermore, the inorganic porous body is preferably formed of a material that forms an inorganic sol. Thereby, an inexpensive inorganic sol can be used, and cost merit is expected. Further, a sol-gel method, which is a simple porous film forming technique, can be used.
The material forming the inorganic sol is preferably an inorganic colloid. The inorganic colloid is suitable for forming a porous film having a three-dimensional ordered arrangement state. For example, an inorganic porous body having a regularly arranged shape can be formed using polymer particles as a template.

  Moreover, the said inorganic porous body is obtained from the suspension liquid (emulsion) which mixed the polymer fine particle and the inorganic material, for example. By applying such a suspension, an inorganic porous body can be obtained using a three-dimensional regular array structure formed by stacking polymer fine particles as a template. In particular, an inorganic porous body having an arbitrary pore size structure can be designed by controlling the particle size and the lamination state of the polymer fine particles. The polymer fine particles in the pores are removed by heat treatment or the like, so that a space for the electrolyte material is secured.

Furthermore, in the inorganic porous body, the inner diameter of the spherical hole is preferably 20 to 1000 nm. If it exceeds 1000 nm, the amount of the proton-donating functional group immobilized per unit weight of the inorganic porous material is small, so that the effect tends to be insufficient. If it is less than 20 nm, formation of a porous body using a spherical resin as a template tends to be difficult. In addition, it is difficult to make technical distinction from nanoscale inorganic porous glass.
The inner diameter of the spherical hole is more preferably 50 to 500 nm. When the thickness is 500 nm or less, the amount of the proton donating functional group immobilized per unit weight of the inorganic porous body increases rapidly, and a sufficient effect can be exhibited. When the thickness is 50 nm or more, it becomes easier to form a porous material using a spherical resin as a template, and a stable porous material can be formed. In addition, the technical area of the nanoscale inorganic porous glass becomes more distinct.

Furthermore, the proton donating functional group is 0.01 to 2 per unit weight of the inorganic porous body from the viewpoint of improving the proton conductivity by favorably fixing the electrolyte material to the desired size of the spherical pore. It is preferable that it is contained at a concentration of .8 mmol / g. If it is less than 0.01 mmol / g, it is difficult to obtain an effect of improving proton conductivity by chemical modification. Further, 2.8 mmol / g is a theoretical value of the functional group modification amount when the inner diameter of the spherical pore is 20 nm, and if it exceeds this, it becomes difficult to form a porous body using the spherical resin as a template.
More preferably, it is contained at a concentration of 0.03 to 1.2 mmol / g. When it is larger than 0.03 mmol / g, the concentration of the proton-donating functional group on the surface of the inorganic porous body is high, and proton conduction on the surface of the inorganic porous body is promoted, which is preferable. Moreover, it is preferable if it is smaller than 1.2 mmol / g because proton donating functional groups can be stably introduced onto the surface.

In the inorganic porous material, the proton-donating functional group that modifies the surface of the spherical pore is preferably a Bronsted acid type functional group.
Examples of the Bronsted acid functional group include a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, and a functional group according to any combination thereof.

  Further, the Equivalent Weight (EW) value of the inorganic porous material itself is 350 to 90000 g / mol from the viewpoint of promoting the proton conductivity on the surface of the porous material and introducing a stable proton donating functional group. Is preferred. More preferably, it is 890 to 33000 g / mol.

Next, the production method of the proton conductive composite electrolyte membrane of the present invention will be described in detail.
In the production method of the present invention, the following step (1) step of mixing an inorganic sol and a spherical organic resin in a solvent to form a suspension (2) step of stirring the suspension and forming a film by filtration (3 ) Step of removing excess moisture from the filter-formed membrane and drying (4) Step of heating and baking the filter-formed membrane to form a porous membrane (5) Chemical modification for introducing a proton-donating functional group into the spherical pores of the porous membrane Step (6) A step of fixing the introduced functional group in the spherical pores to form an inorganic porous body (7) A step of impregnating the obtained inorganic porous body with an electrolyte material to carry out the above-described proton conductive composite electrolyte membrane To manufacture. FIG. 2 shows the flow of the manufacturing procedure.

In step (1) and step (2), the inorganic sol and the spherical organic resin can be dispersed in a homogeneous state.
Further, the filtration in the step (2) is suitable as a method for filling the gap between the spherical organic resin templates with the inorganic sol.
Furthermore, in the step (3), the filtration molded membrane is dried in advance, thereby facilitating the handling of the membrane in the firing step or the like. Next, in step (4), the filter-molded membrane is heated and fired to burn and form an inorganic support using an inorganic sol, and the template resin is burned and removed to form a porous membrane.

  In step (5) and step (6), the electrolyte material is easily fixed by chemically modifying the inside of the spherical pores of the porous membrane. In step (7), the intended proton-conductive composite electrolyte membrane is easily obtained. can get.

Further, in the step (5), a hydroxyl group can be added to the surface in the spherical pore of the inorganic porous body or the hydroxyl group present on the surface can be increased.
For example, as shown in FIG. 3 (upper figure), silanol groups are increased by hydrothermal treatment on the surface of the spherical pores of the inorganic porous material, and mercapto groups are further introduced by a silane coupling agent. Then, the mercapto group can be oxidized to introduce a proton-donating functional group.
In addition, as shown in FIG. 3 (below), protons are donated by increasing silanol groups on the surface of the spherical pores of the inorganic porous material by hydrothermal treatment and further reacting with 1,3-propane sultone in a toluene solution. A functional group can be introduced.

By passing through the said process (1)-(4), the inorganic porous body by which the organic resin material was used as a template and three-dimensional regular arrangement | sequence was obtained.
As the spherical organic resin, for example, polyolefin resin typified by polyethylene of about 20 nm to 1000 nm, polystyrene resin, cross-linked acrylic resin, methyl methacrylate resin, polyamide resin and the like can be appropriately selected. When it is smaller than 20 nm, it is difficult to obtain particles having a uniform particle size distribution at low cost. On the other hand, if it exceeds 1000 nm, the homogeneity of the support structure constituting the inorganic support is disturbed, which is not preferable.
Further, the filtration can be performed at a reduced pressure of about 10 to 60 kPa as appropriate from the size of the spherical pores of the inorganic porous material, the pore density, and the like.
Furthermore, in the step (4), it is preferable to perform preliminary firing for removing the organic resin material in the filtration membrane and then sinter the inorganic porous body. Temporary baking is performed at a heating rate of 1 to 10 ° C./min, preferably 2 to 5 ° C./min, 400 to 500 ° C., more preferably 430 to 470 ° C., and heat treatment is performed for 30 minutes or longer. Can do. Moreover, baking can perform the heat processing for about 30 to 100 minutes, for example at 800-900 degreeC or more. Further, the main baking may be repeated a plurality of times.

Next, the energy device of the present invention will be described.
The energy device of the present invention is configured by applying the above proton conductive composite electrolyte membrane. In this case, a system can be appropriately formed by combining with other control means.
Typically, a fuel cell (cell or stack), water electrolysis, hydrohalic acid electrolysis, salt electrolysis, oxygen concentrator, humidity sensor, gas sensor, and the like can be given.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in full detail, this invention is not limited to these Examples.

Example 1
An inorganic / organic composite electrolyte membrane was prepared by introducing an ionic liquid as an electrolyte material into the pores using a silica porous membrane as a matrix.

1) Preparation of inorganic porous material For the purpose of controlling the pore size of the inorganic porous material, polystyrene spherical particles having an average diameter of about 500 nm were used.
The suspension was prepared by mixing the polystyrene spherical particles having a diameter of about 500 nm and the colloidal silica having a diameter of 70 to 100 nm so that the solute volume contained in the suspension solution had a predetermined film thickness.
As a procedure, first, a predetermined amount of polystyrene was weighed and added to water, and then a colloidal silica-containing container was added to a solution containing polystyrene spherical fine particles. In order to disperse these particles uniformly, ultrasonic stirring was performed.
Next, inorganic porous material was formed by filtration of the suspension. The membrane filter was set in a filter holder, and the pressure was reduced to 10 kPa or less with respect to atmospheric pressure using a manual vacuum pump, and the suspension was filtered.
After all the suspension was filtered, excess water contained in the filter-formed membrane was removed using filter paper as a water absorbing material and sufficiently dried at room temperature. Then, a film made of a mixture of polystyrene and silica was obtained by peeling from the membrane filter.

The obtained film made of a mixture of polystyrene and silica was heat-treated as follows.
Temporary baking was performed to remove polystyrene. The temperature was raised at 2 ° C./min, and heat treatment was performed at that temperature for 30 minutes or more. Further, in order to sinter the silica, a heat treatment was performed at about 800 ° C. or higher for about 60 minutes after the preliminary firing. Furthermore, in order to improve mechanical strength, heat treatment was performed at a temperature of 900 ° C. or higher for 15 minutes, and the temperature was slowly returned to room temperature, thereby obtaining a target inorganic porous body.

2) Chemical modification to the surface in the spherical hole of an inorganic porous body First, the obtained silica porous membrane was hydrothermally treated at 170 ° C. for 24 hours using an autoclave. The increase in silanol groups was confirmed by FT-IR.
Next, mercapto groups were introduced into the porous silica membrane. γ-Mercaptopropyltrimethylsilane was used as a silane coupling agent.
A porous silica membrane was immersed in toluene containing 0.01 mol / l of a silane coupling agent for a predetermined time (100 ° C., 20 hours), and then vacuum-dried at 100 ° C. for 10 minutes.

The absorption of the mercapto group on the surface in the spherical pore was observed by FT-IR. Thereafter, a 10% hydrogen peroxide solution was used to oxidize the 2 hr mercapto group at 70 ° C. to form a sulfonic acid group.
The presence of sulfonic acid groups on the surface was confirmed by observation with ESCA.

Confirmation of the introduction of SiOH groups was measured using FT-IR. An example of the measurement is shown in FIG. The introduction of SiOH groups was confirmed by detecting a peak derived from SiOH groups found at about 3,500-3,700 cm ⁻¹ .
The introduced SO ₃ H group was confirmed by the element ratio of S to Si obtained by measuring the EDS spectrum as shown in FIG.

In addition, as another chemical modification method, for example, impregnation in a toluene solution of 1,3-propanesultone prepared so as to have a concentration of 5% with a hot water-treated porous body using an autoclave is performed at 120 ° C. for 24 hours. By performing the reflux, the SO ₃ H group can be introduced into the pore surface of the inorganic porous body by a one-step reaction. The presence of sulfonic acid groups on the surface can be observed with ESCA as well.

By increasing the SO ₃ H groups introduced per unit area in this way, the amount of functional groups contained in the inorganic / organic composite electrolyte membrane can be increased.
Further, as shown in the graph of FIG. 6, the amount of functional groups contained in the inorganic / organic composite electrolyte membrane can also be increased by increasing the pore surface area contained per unit membrane weight.

3) Impregnation with electrolyte material (ionic liquid) A porous silica membrane whose surface is modified with a sulfonic acid group is impregnated with ionic liquid ( 1-ethyl-3-methylimidazolium hydrogen sulfate ( EMI m HSO ₄ ) ). A composite electrolyte membrane was obtained. A SEM photograph of the cross section of this film is shown in FIG.

(Comparative Example 1)
Only the ionic liquid similar to Example 1 was prepared as an electrolyte material.

(Ion conductivity evaluation)
The composite electrolyte membrane obtained in Example 1 and the electrolyte material of Comparative Example 1 were sandwiched from both surfaces using a gold electrode having a predetermined area, and evaluated by impedance measured by applying an AC wave of 10 Hz to 100 kHz.
Here, the ionic conductivity was calculated based on the area in contact with the gold electrode without considering the porosity. In the measurement, the ionic conductivity was measured by continuously changing the temperature.

As a result, it was confirmed that the composite type electrolyte membrane of Example 1 had better ionic conductivity than the ionic liquid alone.
As shown in FIG. 8, the proton conductive composite electrolyte membrane obtained in Example 1 showed a significant improvement in ionic conductivity with respect to the liquid state.
Also, the EMI m HSO _4, the ionic conductivity in the liquid state as one, the ionic liquid (EMI m HSO ₄₎ a composite electrolyte membrane composed of the electrolyte membrane impregnated on porous silica film surface-modified with a sulfonic acid group The conductivity was compared. The result is shown in FIG. As can be seen from this graph, the electrolyte membrane made of a porous silica material impregnated with an ionic liquid (EMI m HSO ₄ ) had an ionic conductivity improved by 5.5 times compared to the liquid state.

It is the schematic which shows the structure of the electrolyte membrane of this invention typically. It is a flowchart which shows the preparation procedures of a proton conductive composite type electrolyte membrane. It is a conceptual diagram which shows the specific example of the surface modification procedure in the spherical hole of an inorganic porous body. It is a graph which shows the measurement example of IR spectrum before and after sultone processing. It is a graph which shows the example of a measurement of an EDS spectrum. It is a graph which shows the relationship between a pore diameter and the amount of functional groups (concentration). It is a photograph which shows the cross-sectional SEM image of a composite type electrolyte membrane. 4 is a graph showing ionic conductivity of electrolyte membranes obtained in Example 1 and Comparative Example 1. It is the graph which compared ionic conductivity.

Explanation of symbols

1 Inorganic porous material 2 Electrolyte material 3 Electrode material

Claims (5)

A proton conductive composite electrolyte membrane in which an electrolyte material is disposed in a plurality of spherical pores of an inorganic porous body,
The inorganic porous body has spherical holes that exist three-dimensionally in the inorganic porous body, and the spherical holes communicate with each other.
The inorganic porous body has a porosity of 70 to 90%,
The inorganic porous body is formed of at least one metal oxide selected from the group consisting of alumina, silica, titania and zirconia,
The inorganic porous body has a sulfonic acid group on the surface in the spherical hole,
A proton conductive composite electrolyte membrane, wherein the electrolyte material contains 1-ethyl-3-methylimidazolium hydrogen sulfate which is an ionic liquid.   2. An energy device, wherein the proton conductive composite electrolyte membrane according to claim 1 is applied.   A fuel cell, wherein the proton conductive composite electrolyte membrane according to claim 1 is applied. A proton conductive composite electrolyte membrane in which an electrolyte material is disposed in a plurality of spherical pores of an inorganic porous body,
The inorganic porous body has spherical holes that exist three-dimensionally in the inorganic porous body, and the spherical holes communicate with each other.
The inorganic porous body has a porosity of 70 to 90%,
The inorganic porous body is formed of at least one metal oxide selected from the group consisting of alumina, silica, titania and zirconia,
The inorganic porous body has a sulfonic acid group on the surface in the spherical hole,
In producing the proton conductive composite type electrolyte membrane containing 1-ethyl-3-methylimidazolium hydrogen sulfate which is an ionic liquid as the electrolyte material, the following step (1) Inorganic sol and spherical organic resin as solvent (2) A step of stirring the suspension and forming a film by filtration (3) A step of removing excess moisture from the filtration molded membrane and drying (4) A filtration molded membrane Step of heating and baking to form a porous membrane (5) Chemical modification step of introducing a proton-donating functional group into the spherical pores of the porous membrane (6) Step of fixing the introduced functional groups into the spherical pores to form an inorganic porous body (7) A method for producing a proton-conductive composite electrolyte membrane, which comprises a step of impregnating the obtained inorganic porous material with an electrolyte material,
In the above step (5), a hydroxyl group is added to the surface in the spherical pores of the inorganic porous body by a hydrothermal reaction or a hydroxyl group existing on the surface is increased by a hydrothermal reaction, and a mercapto group is further introduced by a silane coupling agent. Thereafter, a mercapto group is oxidized in a hydrogen peroxide solution to introduce a sulfonic acid group, thereby producing a proton conductive composite electrolyte membrane. A proton conductive composite electrolyte membrane in which an electrolyte material is disposed in a plurality of spherical pores of an inorganic porous body,
The inorganic porous body has spherical holes that exist three-dimensionally in the inorganic porous body, and the spherical holes communicate with each other.
The inorganic porous body has a porosity of 70 to 90%,
The inorganic porous body is formed of at least one metal oxide selected from the group consisting of alumina, silica, titania and zirconia,
The inorganic porous body has a sulfonic acid group on the surface in the spherical hole,
In producing the proton conductive composite type electrolyte membrane containing 1-ethyl-3-methylimidazolium hydrogen sulfate which is an ionic liquid as the electrolyte material, the following step (1) Inorganic sol and spherical organic resin as solvent (2) A step of stirring the suspension and forming a film by filtration (3) A step of removing excess moisture from the filtration molded membrane and drying (4) A filtration molded membrane Step of heating and baking to form a porous membrane (5) Chemical modification step of introducing a proton-donating functional group into the spherical pores of the porous membrane (6) Step of fixing the introduced functional groups into the spherical pores to form an inorganic porous body (7) A method for producing a proton-conductive composite electrolyte membrane, which comprises a step of impregnating the obtained inorganic porous material with an electrolyte material,
In the step (5), a hydroxyl group is added to the surface in the spherical pores of the inorganic porous body by a hydrothermal reaction or the hydroxyl group present on the surface is increased by a hydrothermal reaction, and further in 1,3-propane sultone and toluene solution A method for producing a proton-conductive composite electrolyte membrane, wherein a sulfonic acid group is introduced by reacting in step (1).

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