JP2016004658A - Electrolyte membrane, membrane electrode assembly, fuel cell, and method for producing electrolyte membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte membrane which is excellent in gas barrier properties and durability while ensuring a high output, and to provide a membrane electrode assembly, a fuel cell, and a method of producing an electrolyte membrane.SOLUTION: An electrolyte membrane 5 has a membrane body 5a which contains an organic polymer material containing an ion-exchange group conducting protons electrically, and silica particles composed of silica, i.e., an inorganic compound, where an organic system and an inorganic system are hybridized, and the silica particles are dispersed entirely into the membrane body 5a. With such an arrangement, an electrolyte membrane excellent in gas barrier properties and durability while ensuring a high output, a membrane electrode assembly, and a fuel cell can be achieved.

Description

  The present invention relates to an electrolyte membrane, a membrane electrode assembly, a fuel cell, and a method for producing an electrolyte membrane.

  A fuel cell is a device that generates electricity by chemically reacting hydrogen and oxygen, has high energy efficiency, and emits almost no environmental pollutants. ing. A fuel cell includes an anode electrode to which a fuel gas is supplied, a cathode electrode to which an oxidant gas is supplied, and an electrolyte membrane made of a polymer material provided between the anode electrode and the cathode electrode. Is disclosed (for example, Patent Document 1). This type of electrolyte membrane includes an ion exchange group that conducts protons, and the protons can be conducted from the anode electrode to the cathode electrode.

JP 2010-108886 A

  However, in such a fuel cell, high output is desired, and the function of separating the introduced fuel gas and oxidant gas so as not to be mixed (gas barrier properties) is excellent, and the electrolyte membrane is not deteriorated. It is also desired to improve durability so that continuous operation can be performed.

  Therefore, an object of the present invention is to provide an electrolyte membrane, a membrane electrode assembly, a fuel cell, and a method for producing an electrolyte membrane that can obtain high output and are excellent in gas barrier properties and durability.

  The electrolyte membrane of the present invention is an electrolyte membrane used in a fuel cell, which includes an organic polymer material containing an ion exchange group that conducts protons and particles made of an inorganic compound, and is a hybrid of organic and inorganic materials. The film body is characterized in that the particles are dispersed inside the film body.

  Moreover, the membrane electrode assembly of the present invention includes an anode electrode to which fuel is supplied and a cathode electrode to which an oxidant is supplied. Between the anode electrode and the cathode electrode, a membrane electrode assembly is provided. The electrolyte membrane of any one of -6 is provided, It is characterized by the above-mentioned.

  A fuel cell according to the present invention is characterized in that the membrane electrode assembly according to claim 7 or 8 is provided between a pair of separators.

  Further, the method for producing an electrolyte membrane of the present invention includes an organic dispersion in which an organic polymer material containing an ion exchange group that conducts protons is dispersed in an electrolyte membrane used in a fuel cell, and an inorganic system. A mixed solution preparation step for preparing a mixed solution in which a particle forming agent is mixed, and a film body in which particles of an inorganic compound are dispersed are formed by curing the mixed solution into a film by a sol-gel reaction, and organic And a membrane production process for producing an electrolyte membrane in which a hybrid system and an inorganic system are hybridized.

  Further, the method for producing an electrolyte membrane of the present invention is a method for producing an electrolyte membrane used in a fuel cell, wherein a quantum beam is irradiated to all or a part of a membrane body formed of a hydrophobic organic polymer material. Contains a quantum beam irradiation step for forming a hydrophilic region, a graft polymerization step for graft polymerization of styrene monomer to the membrane body, an introduction step for introducing an ion exchange group for conducting protons, and an inorganic particle forming agent. A membrane for producing an electrolyte membrane in which particles made of an inorganic compound are dispersed in the membrane main body by impregnating the membrane main body in an impregnation liquid and cured by a sol-gel reaction, and the organic and inorganic systems are hybridized. And a manufacturing process.

  According to the present invention, it is possible to achieve an electrolyte membrane, a membrane electrode assembly, a fuel cell, and a method for producing an electrolyte membrane that are excellent in gas barrier properties and durability while obtaining high output.

1 is a schematic diagram showing the overall configuration of a fuel cell according to a first embodiment. It is a photograph which shows the cross-sectional structure of an electrolyte membrane. It is the schematic where it uses for description of the manufacturing method of the electrolyte membrane by 1st Embodiment. It is a photograph which shows the electrolyte membrane by 1st Embodiment. It is a photograph which shows the conventional electrolyte membrane. It is a table | surface which shows the verification result of a water-containing film thickness, WU, and IEC about the conventional electrolyte membrane and the electrolyte membrane by 1st Embodiment which changed content of the silica particle. The graph which shows the result of having investigated the relationship between a current density and an output voltage, and the relationship between a current density and an output density about the conventional electrolyte membrane and the electrolyte membrane by 1st Embodiment which changed content of the silica particle It is. It is a table | surface which shows the result of having investigated the OCV, the maximum current density, and the maximum output density about the conventional electrolyte membrane and the electrolyte membrane by 1st Embodiment which changed content of the silica particle. It is a graph which shows the result of having investigated the Cole-Cole plot about the conventional electrolyte membrane and the electrolyte membrane by 1st Embodiment which changed content of the silica particle. It is the schematic where it uses for description of the membrane resistance and reaction resistance which can be read from the waveform of a Cole-Cole plot. 10 is a table showing the results of examining the membrane resistance and reaction resistance of each electrolyte membrane read from the waveform of the Cole-Cole plot shown in FIG. 9. Relationship between current density and output voltage in the humidified state of the conventional electrolyte membrane and in the humidified and non-humidified states of the electrolyte membrane according to the first embodiment with the silica particle content of 7.5 [Wt%] It is a graph which shows the result of having investigated the relationship between current density and output density. OCV, maximum current density, and maximum in the humidified state of the conventional electrolyte membrane and in the humidified and non-humidified states of the electrolyte membrane according to the first embodiment having a silica particle content of 7.5 [Wt%] It is a table | surface which shows the result of having investigated the output density. It is the schematic which shows the whole structure of the fuel cell by 2nd Embodiment. It is the schematic with which it uses for description (1) of the manufacturing method of the membrane electrode assembly by 2nd Embodiment. It is the schematic with which it uses for description (2) of the manufacturing method of the membrane electrode assembly by 2nd Embodiment. When the conventional electrolyte membrane is in a humidified state, when the electrolyte membrane with a silica particle content of 7.5 [Wt%] is in a humidified state and when it is not humidified, and when the electrode is joined to the electrode, the silica particle content is 7.5 [Wt%]. %] Is a graph showing the results of examining the relationship between the current density and the output voltage of the electrolyte membrane in the humidified state and the non-humidified state, and the relationship between the current density and the output density. When the conventional electrolyte membrane is in a humidified state, when the electrolyte membrane with a silica particle content of 7.5 [Wt%] is in a humidified state and when it is not humidified, and when the electrode is joined to the electrode, the silica particle content is 7.5 [Wt%]. %] Is a table showing the results of examining the OCV, the maximum current density, and the maximum output density of the electrolyte membrane in a humidified state and a non-humidified state. When the conventional electrolyte membrane is in a humidified state, when the electrolyte membrane with a silica particle content of 7.5 [Wt%] is in a humidified state and when it is not humidified, and when the electrode is joined to the electrode, the silica particle content is 7.5 [Wt%]. %] Is a graph showing the results of examining a Cole-Cole plot when the electrolyte membrane is in a humidified state and a non-humidified state. 20 is a table showing the results of examining the thickness of each electrolyte membrane and the membrane resistance and reaction resistance of each electrolyte membrane read from the waveform of the Cole-Cole plot shown in FIG. It is the schematic which shows the whole structure of the fuel cell by 3rd Embodiment. It is a chemical formula which shows the molecular structure of the fluorine-type polymer film used as a base material of electrolyte membrane. It is the schematic which shows the manufacturing method of the electrolyte membrane by 3rd Embodiment in steps, FIG. 23A shows the state before irradiating a quantum beam, FIG. 23B shows the state which irradiated the quantum beam and produced | generated the radical FIG. 23C shows a state where a graft chain is generated, and FIG. 23D is a schematic view showing a state where a sulfonic acid group is introduced. FIGS. 24A and 24B are schematic views showing step by step a manufacturing method of an electrolyte membrane according to a third embodiment, FIG. 24A shows a state in which the membrane body is impregnated with an impregnating liquid, and FIG. FIG. 24C is a schematic view showing the manufactured electrolyte membrane, showing a state where ultrasonic waves are applied. FIG. 25A is a graph showing the analysis result of the fluorescent X-ray analysis of the electrolyte membrane (NC) as a comparative example, and FIG. 25B shows the analysis result of the fluorescent X-ray analysis of the electrolyte membrane (S-PFA) as a comparative example. FIG. 25C is a graph showing an analysis result of fluorescent X-ray analysis of the electrolyte membrane (S-PFA / Silica) according to the present invention. For conventional electrolyte membranes, electrolyte membranes that have undergone graft polymerization, and electrolyte membranes that have undergone graft polymerization and contain silica particles in the membrane body, examine the water-containing film thickness, dry film thickness, WU, and swelling rate. It is a table | surface which shows the result. The relationship between current density and output voltage, and relationship between current density and output density, with respect to conventional electrolyte membranes, electrolyte membranes that have undergone graft polymerization, and electrolyte membranes that have undergone graft polymerization and contain silica particles in the membrane body It is a graph which shows the result of having investigated. The film thickness, OCV, maximum current density, and maximum output density were examined for a conventional electrolyte membrane, an electrolyte membrane subjected to graft polymerization, and an electrolyte membrane subjected to graft polymerization and including silica particles in the membrane body. It is a table | surface which shows a result. It is a graph which shows the result of having investigated the Cole-Cole plot about the conventional electrolyte membrane, the electrolyte membrane which performed graft polymerization, and the electrolyte membrane which performed graft polymerization and contains a silica particle in a film | membrane main body. 30 is a table showing the results of examining the membrane resistance and reaction resistance of each electrolyte membrane read from the waveform of the Cole-Cole plot shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(1) First embodiment (1-1) Configuration of fuel cell according to the first embodiment In FIG. 1, reference numeral 1 denotes a fuel cell according to the present invention, and a membrane electrode assembly (MEA) 2 And a cell S provided with a pair of separators 6 and 7 disposed so as to face each other with the membrane electrode assembly 2 interposed therebetween. In the case of this embodiment, as shown in FIG. 1, a fuel cell 1 provided with one cell S will be described. However, the present invention is not limited to this, for example, several tens to several hundreds. It is good also as a fuel cell which has the laminated body (stack) which connected the some cell S which becomes in series.

  Here, the membrane electrode assembly 2 has an anode electrode 3, a cathode electrode 4, and an electrolyte membrane 5 provided between the anode electrode 3 and the cathode electrode 4. Although not shown, the anode electrode 3 and the cathode electrode 4 have a catalyst layer disposed on the electrolyte membrane 5 side and a gas diffusion layer laminated on the catalyst layer, and are joined to the electrolyte membrane 5 with a binder. Has been. In addition, as a catalyst layer, what carried | supported platinum on the carbon particle, the alloy material, etc. can be used, for example. As the gas diffusion layer, carbon cloth or carbon paper can be used.

  One separator 6 supplies fuel to the anode electrode 3, and the other separator 7 paired with the one separator 6 is arranged so as to supply an oxidant to the cathode electrode 4. As the fuel, hydrogen, methanol, ethanol, glucose or the like can be used. Oxygen can be used as the oxidizing agent. The anode electrode 3 and the cathode electrode 4 are electrically connected to an external load 8 (for example, a lighting device such as a light bulb) through a wiring 9 so that electric power can be supplied to the external load 8. Both the fuel and the oxidant may be liquid or gas, one of which may be liquid and the other may be gas.

In the fuel cell 1, when fuel is supplied to the anode electrode 3, hydrogen atoms contained in the fuel are separated into protons (H ⁺ ) and electrons (e ⁻ ), and the protons pass through the electrolyte membrane 5 to the cathode. It is configured to be able to move to the electrode 4. On the other hand, electrons can move from the separator 6 to the cathode electrode 4 through the external load 8 and the separator 7. The cathode electrode 4 can generate water by combining oxygen contained in the supplied oxidant with protons and electrons transferred from the anode electrode 3. When these reactions are expressed in an electrochemical formula, the anode electrode 3 has H ₂ → 2H ⁺ + 2e ⁻ , the cathode electrode 4 has 2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O, and H ₂ + 1 / 2O ₂ → H ₂ as a whole. O.

  In addition to such a configuration, the electrolyte membrane 5 of the present invention includes an organic polymer material containing an ion exchange group that conducts protons and particles made of an inorganic compound, and the organic and inorganic materials are hybridized. The film main body 5a is formed, and particles made of an inorganic compound are dispersed throughout the film main body 5a. Such an electrolyte membrane 5 forms a membrane body 5a by curing a mixed solution (described later) in which at least an organic dispersion and an inorganic particle forming agent are mixed into a membrane by a sol-gel reaction including heat treatment. As a result, it is possible to obtain a configuration in which particles made of an inorganic compound are uniformly dispersed throughout the thickness direction of the film body 5a.

  Examples of the organic polymer material containing an ion exchange group that conducts protons include, for example, “Nafion” (registered trademark) of perfluorosulfonic acid ionomer containing a sulfonic acid group as an ion exchange group. Applicable. Examples of organic polymer materials include fluorine-based polymers such as PTFE (Polytetrafluoroethylene), PVdF (Polyvinylidenefluoride), FEP (Tetrafluoroethylene-Hexafluoropropylene Copolymer), PFA (Tetrafluoroethylene-Perfluoroalkylvinylether Copolymer), and ETFE (Tetrafluoroethylene-Ethylene Copolymer). Molecular materials and cross-linked products thereof can be used.

  In addition, as other organic polymer materials, it is possible to use hydrocarbon polymer materials such as polystyrene, polyetheretherketone, polyimide, polysulfone, polyetherimide, and their cross-linked materials, including structural isomers. it can. Further, as other organic polymer materials, a blend of a fluorine polymer or a hydrocarbon polymer, a molecular complex, a blend of each polymer, or a molecular complex may be applied. In addition to the sulfonic acid group, a carboxylic acid group may be used as the ion exchange group. On the other hand, as particles that are inorganic compounds, for example, silica particles made of silica can be applied.

  FIG. 2 is a photograph showing a cross-sectional configuration of the electrolyte membrane 5 having a film shape at a predetermined position in the film thickness direction. As shown in FIG. 2, in the electrolyte membrane 5 of the present invention, the sulfonic acid group 10 and the silica particles 11 are mixed in the membrane body 5a, and the silica particles 11 are spread over the entire inside of the membrane body 5a. It has a uniformly dispersed configuration. As described above, the electrolyte membrane 5 has high dispersion when used in the fuel cell 1 because the silica particles 11 are dispersed therein, and the silica particles 11 allow the permeation of fuel and oxidant molecules. Thus, the gas barrier property can be improved. Further, since the electrolyte membrane 5 can reduce the crossover of fuel such as hydrogen, oxygen gas, and methanol during power generation by improving the gas barrier property, the membrane deterioration due to the peroxide generated in the crossover can also be reduced. The durability can be improved.

  Here, by setting the content of the silica particles to 7.5 ± 2.0 [Wt%], the electrolyte membrane 5 can obtain higher output and further improve gas barrier properties and durability. . In addition, the electrolyte membrane 5 has a silica particle content of 7.5 ± 2.0 [Wt%], thereby improving shape retention by silica particles, preventing deformation due to swelling, and improving swelling resistance. Can do. The electrolyte membrane 5 of the present invention, which is excellent in gas barrier properties, durability, and swelling resistance and can obtain a high output, can be produced as follows.

(1-2) Method for Producing Electrolyte Membrane The above-described electrolyte membrane 5 of the present invention can be produced by a sol-gel reaction including heat treatment as described below. In this case, first of all, for example, TEOS (tetraethoxysilane) as an inorganic particle forming agent, PrOH, and H ₂ O are contained in a predetermined ratio, and an organic material that includes an ion exchange group that conducts protons. A mixed solution is prepared by mixing an organic dispersion in which a polymer material is dispersed. The mixed solution thus prepared can be cured by a sol-gel reaction including heat treatment.

In addition, as this organic dispersion liquid, for example, Nafion dispersion liquid (manufactured by Nafion (registered trademark, DuPont)) is added to ion-exchanged water and stirred while heating to disperse the Nafion dispersion liquid. it can. In this case, the mixed solution becomes, for example, TEOS, PrOH, and H ₂ O in a predetermined ratio, and becomes a sol by mixing and stirring the Nafion dispersion, and gelled by advancing the reaction. obtain.

  Next, as shown in FIG. 3, a release film 12 made of, for example, an FEP (tetrafluoroethylene-hexafluoropropylene copolymer) film that is a fluororesin film is prepared, and a mixed solution 13 is formed on the surface of the release film 12. Apply. Thus, the mixed solution 13 can be formed on the surface of the release film 12 in a film shape having a predetermined film thickness. Thereafter, the electrolyte solution 5 in which the silica particles 11 made of an inorganic compound are dispersed in the membrane body 5a can be manufactured by curing the mixed solution 13 formed in a film shape by drying and heat treatment. Finally, the electrolyte membrane 5 usable for the membrane electrode assembly 2 can be obtained by peeling the electrolyte membrane 5 from the release film 12.

  As described above, the production method includes an organic polymer material including an ion exchange group that conducts protons, and silica particles 11, and an organic system and an inorganic system are hybridized. Thus, the electrolyte membrane 5 of the present invention in which the silica particles 11 are uniformly dispersed can be produced. The content of the silica particles contained in the electrolyte membrane 5 is adjusted to 7.5 ± 2.0 [Wt%] by adjusting the content ratio of TEOS in the mixed solution 13 when the mixed solution 13 is prepared. Can do. The electrolyte membrane 5 can be produced by making the content of silica particles 7.5 ± 2.0 [Wt%], which is further excellent in gas barrier properties, durability, and swelling resistance, and can obtain higher output. .

(1-3) Verification Test for Electrolyte Membrane According to First Embodiment Next, various verification tests were performed on the electrolyte membrane 5 according to the present invention and the conventional electrolyte membrane. The electrolyte membrane 5 of the present invention was produced by the following procedure. First, TEOS (inorganic particle forming agent), PrOH, and H ₂ O are mixed at a ratio of 1: 4: 4, and a Nafion dispersion (DuPont Nafion Dispersion D521) is further mixed. The mixed solution 13 was prepared by stirring for about 1 hour. Next, the mixed solution 13 was applied in the form of a film on the surface of the release film 12 having a temperature of 60 [° C.], dried for 24 hours, and then heat-treated at 110 [° C.] for 2 hours, whereby the membrane body An electrolyte membrane 5 in which silica particles were dispersed in 5a was produced on the surface of the release film 12. Next, as shown in FIG. 4, the electrolyte membrane 5 produced on the surface of the release film 12 was picked by the tweezers Tw and peeled off from the release film 12 to obtain the electrolyte membrane 5 of the present invention having a thin film shape. The electrolyte membrane 5 thus formed had a silica particle content of 7.5 [Wt%], a water content of 35 [%], a water content of 23 [μm], and a theoretical IEC of 0.83.

Separately, by changing the ratio of TEOS, PrOH, and H ₂ O in the mixed solution, and following the same production conditions, an electrolyte membrane having a silica particle content of 2.5 [Wt%], 5.0 [ A Wt%] electrolyte membrane and a 10 [Wt%] electrolyte membrane were produced as examples. In addition to this, as a comparative example, a thin electrolyte membrane 15 (FIG. 5) was prepared by a cast method using a commercially available Nafion dispersion (DuPont Nafion Dispersion D521). The electrolyte membrane 15 shown in FIG. 5 made from commercially available Nafion does not contain silica particles.

Next, a conventional electrolyte membrane 15 containing no silica particles, and each electrolyte membrane having a silica particle content of 2.5 [Wt%], 5.0 [Wt%], 7.5 [Wt%], and 10 [Wt%] And IEC (Ion Exchange Capacity) [meq / g] indicating the hydrated film thickness [μm], moisture content (hereinafter referred to as WU) [%], and the amount of sulfonic acid groups per unit volume As a result, the results as shown in FIG. 6 were obtained. Incidentally, IEC is represented by IEC = [n (acid _{group) obs]} / _{W d.} Here, [n (acidic group) _obs ] is the amount of acidic group (mM) of the electrolyte membrane, and _Wd is the weight of the electrolyte membrane in the dry state. [N (acidic group) _obs ] was calculated by a neutralization titration method.

In FIG. 6, the conventional electrolyte membrane 15 that does not contain silica particles is denoted as “Nafion cast (NC)”, and the electrolyte membrane with a silica particle content of 2.5 [Wt%] is denoted as “NS _- 2.5”. and, 5.0 to electrolyte membrane [Wt%] _- denoted as "NS 5.0", 7.5 an electrolyte membrane of [Wt%] _- denoted as "NS 7.5", 10 [Wt%] "NS an electrolyte membrane _- 10 ”. In addition, WU (%) was calculated | required by the formula as shown in FIG. 6, However, when calculating | requiring dry mass, each produced electrolyte membrane was dried under reduced pressure with drying oven (VACUUM OVEN VT220 by ETAC THERMOVAC). Dried. In addition, “*” in IEC indicates an expected value from the graft ratio of the sulfonic acid group. From FIG. 6, it was confirmed that the WU (%) of the electrolyte membrane having the silica particle content of 7.5 [Wt%] is the highest and can contain more water.

(1-3-1) Power generation test when hydrogen is 16% humidified and oxygen is not humidified Next, each of these electrolyte membranes is used to manufacture a membrane electrode assembly, and the current density and output When the relationship between the voltage, the relationship between the current density and the output density, and the OCV (Open Circuit Voltage) were examined, the results shown in FIGS. 7 and 8 were obtained. The power generation conditions were a temperature of 60 [° C.], hydrogen as a fuel, and oxygen as an oxidant. Hydrogen was 16 [%] humidified, oxygen was not humidified, and was supplied at 50 [sccm] (8.45 × 10 ⁻² [Pa · m ³ / s), 0.2 [MPa].

The catalyst layer of the anode electrode 3 was formed by applying Pt to carbon paper so that Pt was 1 [mg / cm ² ] and Pt / c was 20 [Wt%]. On the other hand, the catalyst layer of the cathode electrode 4 was formed by applying Pt to carbon paper so that Pt was 1 [mg / cm ² ] and Pt / C was 20 [Wt%]. A Nafion dispersion was used as a binder for joining the cathode electrode 4 and the electrolyte membrane to the anode electrode 3 and the electrolyte membrane.

From FIG. 8, each electrolyte membrane (NS-2.5, NS-5.0, NS-7.5, and NS _- 10) containing silica particles has a higher OCV value than the conventional electrolyte membrane (NC). It was confirmed that the gas barrier properties and durability were improved. Further, from FIGS. 7 and 8, high output was obtained in any of the electrolyte membranes (NS-2.5, NS-5.0, NS-7.5, and NS _- 10) containing silica particles. When using an electrolyte membrane with a silica particle content of 7.5 [Wt%] (NS _- 7.5) or an electrolyte membrane with 10 [Wt%] (NS _- 10), the maximum output density can be confirmed to improve. It was.

Next, for each membrane electrode assembly using each electrolyte membrane, the ordinate represents imaginary impedance (−ImZ [mohm ^* cm ² ]), and the abscissa represents real impedance (ReZ [mohm ^* cm ^2). ]), The results as shown in FIG. 9 were obtained. Further, when the membrane resistance R _S and the reaction resistance R _P were read for each electrolyte membrane from each waveform of the obtained Cole-Cole plot, the result shown in FIG. 11 was obtained.

In FIG. 11, as shown in FIG. 10, the minimum value of the real impedance (ReZ [mohm ^* cm ² ]) is read as the membrane resistance R _{S in} the locus of the Cole-Cole plot, and the Cole-Cole plot is obtained. The diameter of the semicircular waveform was read as the reaction resistance R _P. From FIG. 11, the electrolyte membranes (NS _- 2.5, NS _- 5.0, NS _- 7.5, and NS _- 10) containing silica particles are more preferable than the conventional electrolyte membrane (NC) not containing silica particles. It was confirmed that the resistance R _S was lowered. In addition, in the electrolyte membrane (NS _- 7.5) with a silica particle content of 7.5 [Wt%] or more, both the membrane resistance R _S and the reaction resistance R _P may be lower than the conventional electrolyte membrane (NC). It could be confirmed. Furthermore, it was confirmed that the membrane resistance R _S and the reaction resistance R _P were the lowest in the electrolyte membrane (NS _- 7.5) having a silica particle content of 7.5 [Wt%] or more.

(1-3-2) Power generation test when both hydrogen and oxygen are not humidified Next, while using an electrolyte membrane (NS _- 7.5) with a silica particle content of 7.5 [Wt%], hydrogen and oxygen When the relationship between the current density and the output voltage and the relationship between the current density and the output density when both were not humidified were examined, the results shown in FIGS. 12 and 13 were obtained. In FIGS. 12 and 13, as a power generation condition, “NS _- 7.5” obtained in FIGS. 7 and 8 is compared with a case where hydrogen is 16% humidified and oxygen is not humidified (humidified state). The results are specified again as “NS7.5 (H ₂ RH 16%)”.

Note that the results obtained when using an electrolyte membrane (NS _- 7.5) having a silica particle content of 7.5 [Wt%] and no humidification of both hydrogen and oxygen are shown in FIG. 12 as “NS7.5 (H ₂ RH0%) ”, and“ NS7.5 (no humidification) ”in FIG. From FIG. 12 and FIG. 13, even when the electrolyte membrane has the same silica particle content of 7.5 [Wt%], the maximum current density and the output density are higher in the non-humidified state than in the humidified state. It was confirmed that both values increased. The OCV value is slightly lower than that of the humidified state, 891 [mV], but it is larger than that of the conventional electrolyte membrane (NC). It was confirmed that gas barrier properties and durability were improved.

(1-4) Actions and Effects In the above configuration, the electrolyte membrane 5 according to the present invention includes an organic polymer material containing an ion exchange group that conducts protons, and silica particles 11 made of silica, which is an inorganic compound. The membrane main body 5a in which the organic and inorganic materials are hybridized is provided, and the silica particles 11 are dispersed throughout the inside of the membrane main body 5a. Thus, in the electrolyte membrane 5, when used in the fuel cell 1, the silica particles 11 dispersed in the membrane body 5a can suppress the permeation of fuel and oxidant molecules, and thus improve the gas barrier property.

  Further, in this electrolyte membrane 5, since the crossover of the fuel can be reduced by improving the gas barrier property, the membrane deterioration due to the peroxide caused by the crossover of the fuel can be suppressed correspondingly, and the durability can be improved. . Further, in the electrolyte membrane 5, high output can be obtained by dispersing the silica particles 11 in the membrane body 5a to hybridize the organic and inorganic systems.

  In addition to this, in this electrolyte membrane 5, by adjusting the content of the silica particles 11 dispersed in the membrane body 5a, shape retention can be improved, deformation due to swelling during power generation can be suppressed, and Swellability can also be improved.

  In addition, the electrolyte membrane 5 in which such an organic type and an inorganic type are hybridized includes an organic dispersion in which an organic polymer material containing an ion exchange group that conducts protons is dispersed, and an inorganic particle forming agent. After the mixed solution is prepared, the mixed solution is cured into a film by a sol-gel reaction including heat treatment, thereby forming a film body in which particles made of an inorganic compound are uniformly dispersed throughout.

(2) Second Embodiment (2-1) Configuration of Fuel Cell According to Second Embodiment In FIG. 14, in which parts corresponding to those in FIG. The fuel cell by a form is shown and the binder differs from 1st Embodiment mentioned above. Here, the binder different from the above-described first embodiment will be described by paying attention to the following. The binder for joining the anode electrode 3 and the electrolyte membrane 5 and the binder for joining the cathode electrode 4 and the electrolyte membrane 5 are obtained by curing the mixed solution described in the first embodiment described above by a sol-gel reaction including heat treatment. It can be formed on the bonding surface of the anode electrode 3 to the electrolyte membrane 5, the bonding surface of the cathode electrode 4 to the electrolyte membrane 5, or the electrode bonding surface of the electrolyte membrane 5.

  In practice, the binder contains an organic polymer material containing an ion exchange group that conducts protons and particles made of an inorganic compound, and the organic and inorganic materials are hybridized, and the whole is inorganic. It has a configuration in which particles of a compound are dispersed. Here, as an organic polymer material containing an ion exchange group that conducts protons, for example, “Nafion” (registered trademark) of perfluorosulfonic acid ionomer containing a sulfonic acid group as an ion exchange group, etc. Can be applied. Examples of organic polymer materials include fluorine-based polymers such as PTFE (Polytetrafluoroethylene), PVdF (Polyvinylidenefluoride), FEP (Tetrafluoroethylene-Hexafluoropropylene Copolymer), PFA (Tetrafluoroethylene-Perfluoroalkylvinylether Copolymer), and ETFE (Tetrafluoroethylene-Ethylene Copolymer). Molecular materials and cross-linked products thereof can be used.

  Furthermore, as other organic polymer materials, it is possible to use hydrocarbon polymer materials such as polystyrene, polyetheretherketone, polyimide, polysulfone, polyetherimide, and their cross-linked materials, including structural isomers. it can. Further, as other organic polymer materials, a blend of a fluorine polymer or a hydrocarbon polymer, a molecular complex, a blend of each polymer, or a molecular complex may be applied. In addition to the sulfonic acid group, a carboxylic acid group may be used as the ion exchange group. On the other hand, as particles that are inorganic compounds, for example, silica particles made of silica can be applied.

  In the membrane electrode assembly 17 according to the second embodiment, a binder obtained by hybridizing the above-described organic and inorganic materials is bonded to the anode electrode 3 and the electrolyte membrane 5 and to the cathode electrode 4 and the electrolyte membrane 5. As a result, the gas barrier property and durability of the electrolyte membrane 5 can be further improved, and higher output can be obtained. Here, the binder has a silica particle content of 7.5 ± 5.0 [Wt%], preferably a silica particle content of 7.5 ± 2.0 [Wt%], and has gas barrier properties, durability, and swelling resistance. The performance can be further improved, and further higher output can be obtained.

  Incidentally, in the case of this embodiment, the electrolyte membrane 5 to be joined to the anode electrode 3 and the cathode electrode 4 with a binder is obtained by hybridizing the organic system and the inorganic system according to the first embodiment described above. Although the case where the present invention is applied has been described, the present invention is not limited thereto. For example, an electrolyte membrane (NC) formed by a cast method using a commercially available Nafion dispersion (DuPont Nafion Dispersion D521) is used for the anode electrode 3 and the cathode electrode. When bonding to 4, a binder obtained by hybridizing the above-described organic and inorganic materials may be used. Even in a membrane electrode assembly using an electrolyte membrane (NC) that does not contain such silica particles, by using a binder in which an organic system and an inorganic system are hybridized, The durability can be improved and a high output can be obtained.

(2-2) Manufacturing Method of Membrane / Electrode Assembly Next, a manufacturing method of the membrane / electrode assembly 17 manufactured using a binder in which an organic type and an inorganic type are hybridized will be described below. In this case, for example, an ion exchange group that contains TEOS (tetraethoxysilane), PrOH (ie, 1-propanol), and H ₂ O as inorganic particle forming agents in a predetermined ratio and conducts protons. A mixed solution is prepared by mixing an organic dispersion liquid in which an organic polymer material containing is dispersed. The mixed solution thus prepared can be cured by a sol-gel reaction including heat treatment.

As this organic dispersion liquid, for example, a Nafion dispersion liquid (DuPont Nafion Dispersion D521) can be applied. In this case, for example, TEOS, PrOH, and H ₂ O are mixed at a predetermined ratio, and the mixed solution becomes a sol by mixing and stirring the Nafion dispersion, and can be gelled by advancing the reaction.

  Next, the anode electrode 3 and the cathode electrode 4 were prepared. As shown in FIG. 15, the above-described mixed solution 19 was applied in a film form to the joining surface 18 that joined the electrolyte membrane 5 of the anode electrode 3 and the cathode electrode 4. Thereafter, the mixed solution 19 is cured by heat treatment to form a binder on the bonding surface 18. In addition, such a binder has a silica particle content of, for example, 7.5 ± 5.0 [Wt%], by adjusting the content ratio of TEOS (inorganic particle forming agent) in the mixed solution in the production process, It can be adjusted to 7.5 ± 2.0 [Wt%].

  Next, as shown in FIG. 16, after the electrolyte membrane 5 is sandwiched between the joining surface 18 of the anode electrode 3 and the joining surface 18 of the cathode electrode 4, the anode electrode 3 and the cathode electrode 4 are heated while being pressurized. By performing the pressing, the anode electrode 3, the electrolyte membrane 5 and the cathode electrode 4 can be thermocompression-bonded and integrated to manufacture the membrane electrode assembly 17.

(2-3) Verification Test for Membrane / Electrode Assembly According to Second Embodiment Next, a verification test was performed on power generation characteristics when a binder in which an organic system and an inorganic system were hybridized was used. Here, as an example, the membrane electrode assembly 17 using the electrolyte membrane 5 according to the first embodiment in which the organic and inorganic materials are hybridized and the binder in which the organic and inorganic materials are similarly hybridized is used. Was made. In this case, the electrolyte membrane 5 in which the organic and inorganic materials are hybridized is prepared in the same manner as the above-mentioned “(1-3) Verification test for the electrolyte membrane according to the first embodiment”, and the silica particles An electrolyte membrane (NS _- 7.5) having a W content of 7.5 [Wt%] was prepared.

In addition, as a binder in which organic and inorganic materials are hybridized, first, TEOS, PrOH, and H ₂ O are mixed at a ratio of 1: 4: 4, and a Nafion dispersion is further mixed. This is stirred for about 1 hour to prepare a mixed solution, which is applied to the catalyst layer of the carbon electrode to be the anode electrode 3 and the cathode electrode 4, and is subjected to a sol-gel reaction including drying at 80 [° C.] for 2 hours. A binder having a silica particle content of 7.5 [Wt%] was formed. The catalyst layers of the anode electrode 3 and the cathode electrode 4 had Pt of 1 [mg / cm ² ], and 56.25 [μl] of the mixed solution 19 serving as a binder was applied to the catalyst layer.

Next, between the anode electrode 3 and the cathode electrode 4 on which the binder is formed, an electrolyte membrane (NS _- 7.5) having a silica particle content of 7.5 [Wt%] is sandwiched between 110 [° C.], 8 [MPa], 3 [min The membrane electrode assembly 17 in which the anode electrode 3, the electrolyte membrane 5 and the cathode electrode 4 were integrated was manufactured by hot pressing.

In addition, as a comparative example, an electrolyte membrane (NS _- 7.5) having a silica particle content of 7.5 [Wt%] is used as an anode electrode 3 and a cathode electrode 4 using a conventional binder made of Nafion ionomer. A membrane electrode assembly bonded and integrated was produced. In addition, as a comparative example, a conventional electrolyte membrane in the form of a thin film formed by a cast method using a commercially available Nafion dispersion (DuPont Nafion Dispersion D521) was prepared, and this was converted into a conventional electrolyte membrane made of Nafion ionomer. A membrane electrode assembly was manufactured by bonding to the anode electrode 3 and the cathode electrode 4 using a binder.

As power generation conditions, the temperature was 60 [° C.], hydrogen was used as the fuel, and oxygen was used as the oxidant. Hydrogen is 16 [%] humidified, oxygen is not humidified, and it is supplied at 50 [sccm] (8.45 × 10 ^-2 [Pa · m ³ / s]), 0.2 [MPa]. When the humidification was performed, the relationship between the current density and the output voltage in each membrane electrode assembly and the relationship between the current density and the output density were examined. The results shown in FIGS. 17 and 18 were obtained. .

  In FIGS. 17 and 18, the case where hydrogen is 16% humidified in a membrane electrode assembly using a conventional electrolyte membrane containing no silica particles and a conventional binder is “Nafion cast (NC ) ”. In FIGS. 17 and 18, an electrolyte membrane having a silica particle content of 7.5 [Wt%] is used, but when hydrogen is 16 [%] humidified in a membrane electrode assembly using a conventional binder, “ NS7.5 ”, and when the membrane electrode assembly was not humidified with hydrogen, it was expressed as“ NS7.5RH 0% ”. Further, in FIGS. 17 and 18, hydrogen is added to a membrane electrode assembly using an electrolyte membrane having a silica particle content of 7.5 [Wt%] and a binder having a silica particle content of 7.5 [Wt%]. When [%] humidified, it was expressed as “NS7.5Bin7.5”, and when hydrogen was not humidified in the membrane electrode assembly, it was expressed as “NS7.5Bin7.5RH 0%”.

  From FIG. 17 and FIG. 18, “NS7.5” and “NS7.5Bin7.5” when hydrogen is 16% humidified, and “NS7.5RH 0%” and “when hydrogen is not humidified” In both NS7.5Bin7.5RH 0%, the current density, output voltage, and output density were higher than in “Nafion cast (NC)”, confirming that the power generation capacity was improved. Moreover, the OCV was also increased, and it was confirmed that the gas barrier property and durability were improved.

  Furthermore, from FIG. 17 and FIG. 18, when comparing “NS7.5” and “NS7.5Bin7.5” when hydrogen is 16 [%] humidified, a binder in which organic and inorganic materials are hybridized is used. It was confirmed that NS7.5Bin7.5 had higher current density, output voltage, and output density and improved power generation capacity than NS7.5.

  Similarly, even when comparing NS7.5RH 0% and NS7.5Bin7.5RH 0% when hydrogen is not humidified, NS7 was made using an organic and inorganic hybrid binder. .5Bin7.5RH 0% "had higher current density, output voltage, and output density than" NS7.5RH 0% ", and it was confirmed that the power generation capacity was improved.

Next, “Nafion cast (NC)”, “NS7.5” and “NS7.5Bin7.5” when hydrogen is 16% humidified, and “NS7.5RH when hydrogen is not humidified” For "0%" and "NS7.5Bin7.5RH 0%", the vertical axis represents the imaginary impedance (-ImZ [mohm ^* cm ² ]), and the horizontal axis represents the real impedance (ReZ [mohm ^* cm ² ]), The results as shown in FIG. 19 were obtained.

Furthermore, from each waveform of the obtained Cole-Cole plot, “Nafion cast (NC)”, “NS7.5” and “NS7.5Bin7.5” when hydrogen is 16% humidified, hydrogen When the membrane resistance R _S and the reaction resistance R _P were read for “NS7.5RH 0%” and “NS7.5Bin7.5RH 0%” when the sample was not humidified, the results shown in FIG. 20 were obtained. It was.

From FIG. 20, “NS7.5” and “NS7.5 Bin7.5” when hydrogen was 16% humidified, and “NS7.5RH 0%” and “NS7. It was confirmed that “5Bin7.5RH 0%” had lower membrane resistance R _S and reaction resistance R _P than “Nafion cast (NC)” as a comparative example. Also, from FIG. 20, when comparing the film resistance R _S and the reaction resistance R _P between “NS7.5” and “NS7.5 Bin7.5” when hydrogen is 16%, the organic and inorganic It was confirmed that the film resistance R _S and the reaction resistance R _P were lower in “NS7.5 Bin7.5” using a hybrid binder of the system than in “NS7.5”.

Further, from FIG. 20, when comparing the film resistance R _S and the reaction resistance R _P between “NS7.5RH 0%” and “NS7.5 Bin7.5RH 0%” when hydrogen is not humidified, It was confirmed that the film resistance R _S was lower in “NS7.5 Bin7.5RH 0%” using an inorganic hybrid binder than in “NS7.5RH 0%”.

(2-4) Action and Effect In the above configuration, the membrane electrode assembly 17 includes an organic polymer material containing an ion exchange group that conducts protons, and silica particles 11 made of silica, which is an inorganic compound, The membrane body 5a in which the organic and inorganic materials are hybridized is provided, and the electrolyte membrane 5 in which the silica particles 11 are uniformly dispersed is provided in the entire inside of the membrane body 5a.

  In addition, this membrane electrode assembly 17 includes an organic polymer material containing an ion exchange group that conducts protons and silica particles made of silica, which is an inorganic compound, and is a hybrid of organic and inorganic materials. The anode electrode 3, the electrolyte membrane 5, and the cathode electrode 4 were joined and integrated using a binder in which silica particles were dispersed throughout.

  Thereby, in the membrane electrode assembly 17, in addition to the effect of the first embodiment described above, the silica particles dispersed in the binder can also suppress the permeation of the molecules of the fuel and the oxidant, and thus the gas barrier property. Can improve. Further, in this membrane electrode assembly 17, since the crossover of the fuel is reduced also by the improvement of the gas barrier property due to the silica particles in the bindery, the membrane deterioration due to the peroxide caused by the fuel crossover is further enhanced. It can be suppressed and the durability can be improved accordingly. Further, in this membrane electrode assembly 17, high output can be obtained by dispersing silica particles in a binder and hybridizing an organic system and an inorganic system. In addition, the membrane electrode assembly 17 has a structure in which silica particles are dispersed in the binder, so that the shape retention is improved, and deformation due to swelling during power generation can be suppressed. Swellability can also be improved.

(3) Third Embodiment (3-1) Configuration of Fuel Cell According to Third Embodiment In FIG. 21, in which parts corresponding to those in FIG. The configuration of the electrolyte membrane 28 constituting the membrane electrode assembly 21 is different from that of the fuel cell 1 according to the first embodiment and the fuel cell 16 according to the second embodiment. Yes. Here, the electrolyte membrane 28 different from the configurations of the first embodiment and the second embodiment described above will be described by paying attention to the following. In the case of this embodiment, the electrolyte membrane 28 includes an organic polymer material containing an ion exchange group that conducts protons and particles made of an inorganic compound, and the organic and inorganic materials are hybridized. A film body 28a is provided, and particles (not shown) made of an inorganic compound are uniformly dispersed throughout the inside of the film body 28a.

  Examples of organic polymer materials include PTFE (Polytetrafluoroethylene), PVdF (Polyvinylidenefluoride), FEP (Tetrafluoroethylene-Hexafluoropropylene Copolymer), PFA (Tetrafluoroethylene-Perfluoroalkylvinylether Copolymer), ETFE (Tetrafluoroethylene-Ethylene Copolymer), etc. Molecular materials and cross-linked products thereof can be used.

  In addition, as other organic polymer materials, it is possible to use hydrocarbon polymer materials such as polystyrene, polyetheretherketone, polyimide, polysulfone, polyetherimide, and their cross-linked materials, including structural isomers. it can. Further, as other organic polymer materials, a blend of a fluorine polymer or a hydrocarbon polymer, a molecular complex, a blend of each polymer, or a molecular complex may be applied. In addition to the sulfonic acid group, a carboxylic acid group may be used as the ion exchange group. On the other hand, as particles that are inorganic compounds, for example, silica particles made of silica can be applied.

  The membrane body 28a has a hydrophilic structure in which a graft chain is formed on such an organic polymer material in the manufacturing process, and a sulfonic acid as an ion exchange group is formed in the hydrophilic region. It has a configuration in which a group is introduced. In addition to this, the electrolyte membrane 28 is manufactured by being impregnated in an impregnating liquid containing an inorganic particle forming agent (described later) and then cured by a sol-gel reaction including heat treatment in the manufacturing process, Within the hydrophilic region of the membrane body 28a, the particles are uniformly dispersed, and the organic and inorganic systems are hybridized.

  Thus, in the electrolyte membrane 28 according to the third embodiment, for example, silica particles are dispersed in the membrane body 28a, so that a high output can be obtained when used in the fuel cell 20, and the silica particles Permeation of fuel and oxidant molecules can be suppressed, and thus gas barrier properties can be improved. In addition, since the electrolyte membrane 28 can reduce the crossover of fuel such as hydrogen, oxygen gas, methanol, etc. during power generation by improving the gas barrier property, the membrane deterioration due to peroxide generated in the crossover can also be reduced. The durability can be improved. Here, in the electrolyte membrane 28, the content of silica particles is adjusted to 7.5 ± 2.0 [Wt%], so that the gas barrier property, durability and swelling resistance can be further improved, and further higher output can be obtained. be able to.

(3-2) Manufacturing Method of Electrolyte Membrane According to Third Embodiment Next, a manufacturing method of the electrolyte membrane 28 in FIG. 21 will be described below. In this case, for example, a film body using a fluorine-based polymer film (PFA) represented by a molecular structure as shown in FIG. 22 as a base material is prepared. Next, a part or the whole of the film body 31 (FIG. 23A) having the polymer chain 32 is irradiated with a quantum beam, and a part of the polymer chain 32 is cut to generate radicals 33 (FIG. 23B). Next, by immersing the membrane body 31 in a reaction solution containing a styrene monomer, the radical 33 becomes an active species of the reaction, the styrene monomer and the radical 33 are bonded, and a graft chain 34 is generated (FIG. 23C). . In this way, the styrene monomer is graft-polymerized on the film body. The reaction solution can be copolymerized by containing divinylbenzene in addition to the styrene monomer. Thereafter, by introducing a sulfonic acid group 35 as an ion exchange group, a membrane body 31 including an ion exchange group and having hydrophilicity can be obtained (FIG. 23D).

At this time, the grafting yield (GY) in the membrane body 31 is desirably 8.0 [%] or more. The graft rate [%] is expressed as 100 (W ₂ −W ₁ ) / W ₁ . Here, W ₁ is the weight of the electrolyte membrane in a dry state before graft chain formation, and W ₂ is the weight of the electrolyte membrane in a dry state after graft chain formation.

As the quantum beam, for example, an electron beam, an ion beam, a neutron beam, or a γ ray can be used. The irradiation conditions of the electron beam are not particularly limited. For example, the acceleration voltage is 150 [kV] to 200 [kV], the current value is 1.0 [mA], the absorbed dose per pass is 50 [kGy], and the N ₂ atmosphere. It can be. The ion beam irradiation conditions are not particularly limited. For example, energy 6 [MeV / u], irradiation dose 1.0 × 10 ¹⁰ [ions / cm ² ], flux 2.45 × 10 ⁸ [ions / sec · cm] ² ] and in vacuum (5 × 10 ⁻⁴ [Pa] or less).

Next, TEOS (tetraethoxysilane) as an inorganic particle forming agent, H ₂ O, and MeOH are mixed at a predetermined ratio to prepare an impregnating liquid containing silica particles, as shown in FIG. The membrane main body 31 is immersed in the impregnating liquid 42 stored in the container 40. In addition, as a ratio of TEOS, H ₂ O, and MeOH, for example, TEOS: H ₂ O: MeOH (methanol) = 1: 50: 50 (mol ratio) is preferable.

  Next, as shown in FIG. 24B, the impregnating liquid 42 is impregnated into the membrane main body 31 by performing ultrasonic cleaning by applying ultrasonic waves while the membrane main body 31 is immersed in the impregnating liquid 42. Next, after the membrane body 41 is taken out from the impregnating liquid 42, it is washed with purified water and subjected to proton treatment, whereby the electrolyte membrane 28 of the present invention can be manufactured as shown in FIG. 24C. The electrolyte membrane 28 manufactured in this manner includes an organic polymer material containing an ion exchange group that conducts protons and silica particles made of silica, which is an inorganic compound, and a hybrid of organic and inorganic materials. The film body 28a can be provided, and the silica particles can be uniformly dispersed throughout the inside of the film body 28a.

(3-3) Verification Test for Membrane / Electrode Assembly According to Third Embodiment Next, the electrolyte membrane according to the third embodiment described above was manufactured and various verification tests were performed. In this case, as a comparative example, commercially available Nafion (product name NRE-212 manufactured by Nafion registered trademark DuPont) was prepared as an electrolyte membrane (NC). Next, as another comparative example, an electrolyte membrane was prepared according to the following procedure. First, a PFA film having a film thickness of 25 [μm] was prepared as a film body before processing, and a radical was generated by irradiating the entire surface of the film body with a quantum beam. At this time, an electron beam (Curetron manufactured by NHV Corporation) is used as a quantum beam, and an acceleration voltage of 200 [kV], a current value of 1.0 [mA], an absorbed dose per pass of 50 [kGy], and an N ₂ atmosphere are applied to the film body. Irradiated. Subsequently, the membrane body was immersed in a reaction solution containing a styrene monomer to introduce sulfonic acid groups. As a result, an electrolyte membrane having a membrane main body with a graft ratio of 34 [%] and a water-containing film thickness of 44 [μm] was produced. In this verification test, an electrolyte membrane comprising a membrane body containing a sulfonic acid group and having a graft ratio of 34% was also prepared as a comparative example (this electrolyte membrane is also referred to as S-PFA).

Next, separately from this, an electrolyte membrane 28 as an example was produced by the following procedure. In this case, TEOS, H ₂ O, and MeOH were mixed at a ratio of 1:50:50 (mol ratio) to prepare an impregnation solution. Next, after immersing the electrolyte membrane (S-PFA) containing the sulfonic acid group described above and having a graft ratio of 34% in the impregnating liquid, the impregnating liquid is irradiated with 30 [min] ultrasonic waves. The electrolyte membrane (S-PFA) was sufficiently impregnated and then cured by a sol-gel reaction to produce an electrolyte membrane 28 as an example (hereinafter referred to as S-PFA / Silica).

  Then, X-ray fluorescence elemental analysis was performed on each of the electrolyte membranes of these comparative examples (NC, S-PFA) and Example (S-PFA / Silica), and the results are shown in FIGS. 25A, 25B, and 25C. The result was obtained. FIG. 25A shows the analysis result of the fluorescent X-ray analysis of the electrolyte membrane (NC) as a comparative example, and FIG. 25B shows the analysis result of the fluorescent X-ray analysis of the electrolyte membrane (S-PFA) as a comparative example. 25C shows the analysis result of the fluorescent X-ray analysis of the electrolyte membrane (S-PFA / Silica) according to the present invention. From the results of FIG. 25A, FIG. 25B, and FIG. 25C, the electrolyte membrane (NC, S-PFA) of the comparative example does not show any peak (109 [deg]) indicating the presence of silica, On the other hand, the electrolyte membrane (S-PFA / Silica) as an example showed a peak indicating the presence of silica as an inorganic compound. From this, it was confirmed that the electrolyte membrane (S-PFA / Silica) as an example had silica and was able to hybridize an organic system and an inorganic system.

  Next, regarding the electrolyte membranes of these comparative examples (NC, S-PFA) and the electrolyte membranes of the examples (S-PFA / Silica), the water-containing film thickness (μm), the dry film thickness (μm), and WU ( %) And the swelling rate (%) were examined, and the results shown in FIG. 26 were obtained. The dry film thickness is a film thickness measured with a micrometer after drying the electrolyte membrane by heating at 60 [° C.] for 2 hours.

  From the results of FIG. 26, the electrolyte membrane 28 of the example manufactured by immersing the membrane body in the impregnating solution by the sol-gel reaction contains an electrolyte membrane (S) containing a sulfonic acid group as a comparative example and having a graft ratio of 34%. As compared with -PFA), the swelling rate was low, and it was confirmed that deformation due to swelling was suppressed.

Next, for the electrolyte membranes of these comparative examples (NC, S-PFA) and the electrolyte membrane of the example (S-PFA / Silica), the relationship between the current density and the output voltage, and the relationship between the current density and the output density As a result, the results as shown in FIGS. 27 and 28 were obtained. The power generation conditions used here were a temperature of 60 [° C.], hydrogen as a fuel, and oxygen as an oxidant. Hydrogen was 16% humidified. The catalyst layer of the anode electrode 3 was formed by applying Pt to carbon paper so that Pt was 1 [mg / cm ² ] and Pt / c was 20 [wt%]. The catalyst layer of the cathode electrode 4 was formed by applying Pt to carbon paper so that Pt was 1 [mg / cm ² ] and Pt / c was 20 [wt%].

  27 and 28, the electrolyte membrane (S-PFA / Silica) of the example is also referred to as “impregnated membrane”. From the results of FIGS. 27 and 28, the electrolyte membrane (S-PFA / Silica: impregnated membrane) of the example in which silica particles are dispersed in the membrane body is the electrolyte membrane (NC) of the comparative example and other comparisons. Compared to the electrolyte membrane (S-PFA) in the example, it was confirmed that the current density, output voltage, and output density were improved. In addition, the electrolyte membrane (S-PFA / Silica: impregnated membrane) in which the silica particles are dispersed in the membrane body is the electrolyte membrane (NC) of the comparative example or the electrolyte membrane (S-PFA) of another comparative example. Compared to), the OCV increased, confirming that the gas barrier properties and durability were improved.

Next, membrane electrode assemblies prepared using the electrolyte membrane (NC) of these comparative examples, the electrolyte membrane (S-PFA) of other comparative examples, and the electrolyte membrane 28 (S-PFA / Silica) of the examples. Each time, the Cole-Cole plot showing the imaginary impedance (−ImZ [mohm ^* cm ² ]) on the vertical axis and the real impedance (ReZ [mohm ^* cm ² ]) on the horizontal axis was examined. The result as shown in FIG. 29 was obtained. Further, when the membrane resistance R _S and the reaction resistance R _P were read for each electrolyte membrane from each waveform of the obtained Cole-Cole plot, the result as shown in FIG. 30 was obtained.

In FIG. 30, as shown in FIG. 10, the minimum value of the real impedance in the locus of the Cole-Cole plot is the membrane resistance R _S , while the diameter of the semicircular waveform of the Cole-Cole plot is The reaction resistance is R _P. FIG. 30 shows that the electrolyte membrane (S-PFA / Silica: impregnated membrane) in which the silica particles are dispersed in the membrane body is the electrolyte membrane (NC) of the comparative example or the electrolyte membrane (S It was confirmed that the reaction resistance R _P could be reduced, although the film resistance R _S was increased as compared to -PFA).

(3-4) Actions and Effects In the above configuration, the electrolyte membrane 28 includes an organic polymer material containing an ion exchange group that conducts protons, and silica particles made of silica, which is an inorganic compound. A film body 28a hybridized with an inorganic material was provided, and silica particles were uniformly dispersed inside the film body 28a. Thereby, in the electrolyte membrane 28, when used in the fuel cell 20, the silica particles dispersed in the membrane main body 28a can suppress the permeation of molecules of the fuel and the oxidant, and thus the gas barrier property can be improved.

  Further, in the electrolyte membrane 28, since the crossover of the fuel can be reduced by improving the gas barrier property, the membrane deterioration due to the peroxide generated by the crossover of the fuel can be suppressed correspondingly, and the durability can be improved. Further, in the electrolyte membrane 28, high output can be obtained by dispersing silica particles in the membrane body 28a to hybridize the organic and inorganic systems.

  In addition, the electrolyte membrane 28 has a configuration in which silica particles are dispersed in the membrane main body 28a, so that shape retention is improved, so that deformation due to swelling during power generation can be suppressed, and swelling resistance can be suppressed. Can be improved.

  In such a manufacturing method of the electrolyte membrane 28, first, a hydrophilic region is formed by irradiating a quantum beam to all or part of the membrane body made of a hydrophobic organic polymer material. After that, styrene monomer is graft-polymerized in the hydrophilic region of the membrane body. Next, after introducing an ion exchange group that conducts protons, the membrane body is impregnated with an impregnating liquid containing an inorganic particle forming agent and cured by a sol-gel reaction, thereby containing an organic polymer material and silica particles. In addition, the electrolyte membrane 28 in which the organic type and the inorganic type are hybridized can be manufactured.

(4) Other Embodiments In the case of the third embodiment described above, a graft chain is formed on the entire surface of the membrane body 28a so as to have hydrophilicity, and the entire inside of the membrane body 28a is sulfonated. Although the electrolyte membrane 28 in which the impregnating solution is contained in this region and cured by the sol-gel reaction after the introduction of the group has been described, the present invention is not limited thereto, and a graft chain is formed only in a partial region of the membrane body 28a. The electrolyte membrane may be made hydrophilic so that a sulfonic acid group is introduced only into a partial region of the membrane main body 28a, and an impregnating solution is contained in the partial region and cured by a sol-gel reaction.

  In this case, the electrolyte membrane can be composed of a hydrophilic portion containing an ion exchange group that conducts protons and a hydrophobic portion formed of a hydrophobic material, and particles of an inorganic compound can be dispersed in the hydrophilic portion.

  In order to manufacture this type of electrolyte membrane, first, a hydrophilic region is formed by irradiating a part of the membrane body formed of a hydrophobic organic polymer material with a quantum beam, and then The graft chain is formed in the sex region. Next, a sulfonic acid group is introduced into the hydrophilic part having hydrophilicity, and the hydrophilic part is cured in a state in which particles of the inorganic compound are uniformly dispersed in the hydrophilic part by a sol-gel reaction. An electrolyte membrane in which particles of an inorganic compound are dispersed can be produced. In this case, the electrolyte membrane can be formed so as to surround the periphery of the hydrophilic portion by selectively irradiating the quantum beam in the manufacturing process to form the hydrophobic portion in a lattice shape, for example. .

  In the above-described third embodiment, the membrane electrode assembly 21 in which the electrolyte membrane 28 is joined to the anode electrode 3 and the cathode electrode 4 by using a conventional binder is manufactured. The second embodiment is not limited to this, and includes an organic polymer material containing an ion exchange group that conducts protons and silica particles made of silica, which is an inorganic compound, and a hybrid of organic and inorganic materials. The membrane electrode assembly 21 may be formed by bonding the electrolyte membrane 28 to the anode electrode 3 and the cathode electrode 4 and using the binder of the form.

  Similar to the second embodiment described above, such a membrane electrode assembly suppresses permeation of fuel and oxidant molecules even when used in a fuel cell, even with silica particles dispersed in a binder. Thus, gas barrier properties can be improved. Further, in this membrane electrode assembly, fuel crossover is reduced by improving the gas barrier property, and accordingly, membrane deterioration due to peroxide caused by fuel crossover can be further suppressed, and durability is improved. It can improve. Furthermore, in this membrane electrode assembly, the output voltage can be improved by dispersing silica particles in the binder and hybridizing the organic and inorganic systems.

  In this case, in the membrane / electrode assembly, since the binder is also composed of silica particles dispersed therein, the shape retention is improved accordingly, deformation due to swelling during power generation can be suppressed, and swelling resistance can be improved. Can also be improved.

  Furthermore, in the first to third embodiments described above, a polymer electrolyte fuel cell (PEFC) using hydrogen as a fuel and oxygen as an oxidant has been described as a fuel cell. However, the present invention is not limited to this, and a direct methanol fuel cell (DMFC) using methanol as a fuel instead of hydrogen and using oxygen as an oxidant may be applied.

In the first to third embodiments described above, the cationic electrolyte membranes 5 and 28 in which cations (H ⁺ ) move and the fuel cells 1, 16, and 20 using the same cationic binder are used. It has been described, the present invention is not limited thereto, OH ^- or the like of the electrolyte membrane anionic anion moves, also the fuel cell using anionic binder, an electrolyte membrane 5 and 28 and membrane electrode of the present invention The joined bodies 2 and 21 may be applied.

1, 16, 20 Fuel cell
2, 21 Membrane electrode assembly
3 Anode electrode
4 Cathode electrode
5, 28 Electrolyte membrane
5a, 28a Membrane body
10 Sulfonic acid groups (ion exchange groups)
11 Silica particles (particles)

Claims (14)

In electrolyte membranes used in fuel cells,
An organic polymer material containing an ion exchange group that conducts protons and particles made of an inorganic compound, and having a membrane body in which an organic system and an inorganic system are hybridized,
The electrolyte membrane, wherein the particles are dispersed inside the membrane body. The electrolyte membrane according to claim 1, wherein the inorganic compound is silica, and silica particles are dispersed in the membrane body as the particles. 3. The electrolyte membrane according to claim 2, wherein the content of the silica particles in the membrane body is 7.5 ± 2.0 [Wt%]. The electrolyte membrane according to any one of claims 1 to 3, wherein the membrane main body in which the particles are dispersed is formed by a sol-gel reaction. 5. The membrane body according to claim 1, wherein the membrane main body includes a hydrophilic portion having hydrophilicity including the ion exchange group and a hydrophobic portion formed of a hydrophobic material. Electrolyte membrane. The membrane body is
The electrolyte membrane according to claim 5, wherein the hydrophilic portion is formed by graft polymerization. An anode electrode supplied with fuel;
A cathode electrode supplied with an oxidizing agent,
The membrane electrode assembly, wherein the electrolyte membrane according to any one of claims 1 to 6 is provided between the anode electrode and the cathode electrode. 8. The anode electrode and the electrolyte membrane and at least one of the cathode electrode and the electrolyte membrane are joined by a binder containing particles made of an inorganic compound. The membrane electrode assembly as described. The membrane electrode assembly according to claim 8, wherein the particles contained in the binder are silica particles. The membrane electrode assembly according to claim 9, wherein the content of the silica particles contained in the binder is 7.5 ± 5.0 [Wt%]. A fuel cell comprising the membrane electrode assembly according to claim 7 or 8 between a pair of separators. In a method for producing an electrolyte membrane used in a fuel cell,
A mixed solution preparation step of preparing a mixed solution in which an organic dispersion liquid in which an organic polymer material containing an ion exchange group that conducts protons is dispersed and an inorganic particle forming agent are mixed;
A film preparation step of forming an electrolyte membrane in which an organic system and an inorganic system are hybridized by forming a film body in which particles made of an inorganic compound are dispersed by curing the mixed solution into a film by a sol-gel reaction; A method for producing an electrolyte membrane, comprising: The method for producing an electrolyte membrane according to claim 12, wherein the organic polymer material contains an ion exchange group that conducts protons. In a method for producing an electrolyte membrane used in a fuel cell,
Quantum beam irradiation step of forming a hydrophilic region by irradiating a quantum beam to all or a part of a film body formed of a hydrophobic organic polymer material;
A graft polymerization step of graft-polymerizing a styrene monomer on the membrane body;
An introduction step of introducing an ion exchange group that conducts protons;
The membrane body is impregnated with an impregnating liquid containing an inorganic particle forming agent and cured by a sol-gel reaction to disperse particles made of an inorganic compound in the membrane body, thereby hybridizing the organic and inorganic systems. A method for producing an electrolyte membrane, comprising: a membrane production step for producing an electrolyte membrane.

Images