KR100739643B1 - Polymer electrolyte membrane for fuel cell, membrane-electrode assembly and fuel cell system comprising same - Google Patents

Abstract

Provided are a polymeric electrolyte membrane for a fuel cell, which has excellent proton conductivity and is effective in preventing fuel crossover, and a fuel cell system comprising the same, which exhibits excellent battery performances. The polymeric electrolyte membrane for a passive type direct oxidation fuel cell comprises a cation exchange resin, and a silicate having a proton-conducting group at the terminal. A mixing weight ratio of the cation exchange resin and the silicate is 98-90:2-10. The silicate has a major axis length of 0.05-0.5mum. The proton-conducting group is a sulfonic acid group. The silicate is selected from the group consisting of pyrophylite-talc, montmorillonite, fluorohectorite, kaolinite, vermiculite, illite, mica, and brittle mica.

Description

TECHNICAL FIELD [0001] The present invention relates to a polymer electrolyte membrane for a fuel cell, a membrane-electrode assembly for a fuel cell including the membrane, and a fuel cell system including the membrane-

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically shows the structure of a membrane-electrode assembly for a fuel cell of the present invention. FIG.

2 is a schematic view showing the structure of a fuel cell system of the present invention.

3 is a graph showing X-ray diffraction peaks of the polymer electrolyte membranes of Examples 1 to 3 of the present invention.

4 is a graph showing the methanol permeability of the polymer electrolyte membranes of Examples 1 to 3, Examples 6 to 10, and Comparative Example 1 of the present invention.

5 is a graph showing the ionic conductivity of the polymer electrolyte membranes of Examples 1, 2, 4 and 5, Reference Examples 1 to 6, and Comparative Example 1 measured.

6 is a graph showing output densities of fuel cells manufactured according to Example 2 of the present invention.

7 is a graph showing the output density of the fuel cell of Comparative Example 1. Fig.

[Industrial Applications]

The present invention relates to a polymer electrolyte membrane for a fuel cell, a membrane-electrode assembly for a fuel cell including the same, and a fuel cell system including the same. More particularly, the present invention relates to a polymer electrolyte membrane for fuel cells, A polymer electrolyte membrane, a membrane-electrode assembly for a fuel cell including the same, and a fuel cell system including the membrane-electrode assembly.

BACKGROUND ART [0002]

A fuel cell is a power generation system that directly converts the chemical reaction energy of hydrogen and oxygen contained in a hydrocarbon-based material such as methanol, ethanol, and natural gas into electrical energy. This fuel cell is a clean energy source that can replace fossil energy. It has the advantage of being able to output a wide range of output by stacking the unit cells by stacking them. The fuel cell has a 4-10 times energy density So that it is attracting attention as a compact and portable portable power source.

Representative examples of the fuel cell include a polymer electrolyte membrane cell (PEMFC) and a direct oxidation fuel cell (Fuel Cell). When methanol is used as the fuel in the direct oxidation type fuel cell, it is referred to as a direct methanol fuel cell (DMFC).

The polymer electrolyte fuel cell has advantages such as high energy density and high output. However, it is necessary to pay careful attention to the handling of hydrogen gas. In order to produce hydrogen as a fuel gas, fuel reforming for reforming methane, methanol, There is a problem that an additional equipment such as a device is required.

On the other hand, direct oxidation fuel cells have lower energy density than polymer electrolyte fuel cells, but they are easy to handle and operate at a low temperature and can be operated at room temperature. In particular, there is an advantage that a fuel reforming device is not required.

In such a fuel cell system, the stack for generating electricity may include a plurality of unit cells each consisting of a membrane-electrode assembly (MEA) and a separator (also referred to as a bipolar plate) To several tens of layers. The membrane-electrode assembly is referred to as an anode (also referred to as a "fuel electrode" or an "oxidizing electrode") and a cathode electrode (also referred to as a "cathode" or a "reducing electrode") with a polymer electrolyte membrane containing a proton- ) Are located.

The principle of generating electricity in the fuel cell is that the fuel is supplied to the anode electrode as the fuel electrode and adsorbed to the catalyst of the anode electrode, the fuel is ionized by the oxidation reaction and the electrons are generated, Reaches the cathode electrode, and the hydrogen ions pass through the polymer electrolyte membrane and are transferred to the cathode electrode. An oxidant is supplied to the cathode electrode, and the oxidant, hydrogen ions, and electrons react with each other on the catalyst of the cathode electrode to generate electricity while generating water.

An object of the present invention is to provide a polymer electrolyte membrane for a fuel cell which is excellent in hydrogen ion conductivity and excellent in the effect of preventing crossover of fuel.

Another object of the present invention is to provide a membrane-electrode assembly for a fuel cell comprising the polymer electrolyte membrane.

Still another object of the present invention is to provide a fuel cell system including the membrane-electrode assembly.

In order to achieve the above object, the present invention provides a polymer electrolyte membrane for a fuel cell comprising a cation exchange resin and a silicate having a proton conductive group at a terminal.

The present invention also provides a membrane-electrode assembly for a fuel cell comprising the polymer electrolyte membrane and including an anode electrode and a cathode electrode respectively located on both sides of the polymer electrolyte membrane.

The present invention also provides a fuel cell system including at least one electricity generating portion, a fuel supplying portion and an oxidizing agent supplying portion. The electricity generating portion includes an anode electrode and a cathode electrode positioned opposite to each other, and a polymer electrolyte membrane disposed between the anode electrode and the cathode electrode. In addition, the electricity generating unit generates electricity through the oxidation reaction of the fuel and the reduction reaction of the oxidant. The fuel supply unit supplies fuel to the electricity generation unit, and the oxidant supply unit supplies the oxidant to the electricity generation unit.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a polymer electrolyte membrane for a fuel cell, wherein the polymer electrolyte membrane of the present invention comprises a cation exchange resin and a silicate having a proton conductive group at the terminal.

The silicate can reduce an increase in mechanical strength and crossover of the fuel, and further includes a hydrogen ion conductive group at the end, so that the silicate has excellent hydrogen ion conductivity. Therefore, it is possible to provide a fuel cell excellent in performance, since crossover of a fuel, which is a physical property which is required for a polymer electrolyte membrane for a fuel cell in recent years, in particular, crossover of a hydrocarbon fuel is prevented while hydrogen ion conductivity is also excellent. Therefore, the polymer electrolyte membrane for a fuel cell of the present invention is highly preferable for a direct oxidation type fuel cell using a hydrocarbon fuel. Particularly, the polymer electrolyte membrane for a fuel cell of the present invention is most preferable for a passive type fuel cell system that injects a high concentration of fuel in a diffusion method, even when a high concentration of fuel is used, and is excellent in a crossover prevention effect.

The hydrogen ion conductive group is most preferably a sulfonic acid group. Since the hydrogen ion conductive group is bonded to the end of the silicate, it is preferable not only to improve the hydrogen ion conductivity but also to widen the distance between the plate surfaces of the silicate layered structure.

The silicate of the present invention is a clay, that is, generally a layered silicate, and the basic structure is composed of a combination of a silica tetrahedral sheet and an alumina octahedral sheet, Thereby forming a layered structure.

The silicate can be selected from the group consisting of pyrophyllite-talc, montmorilonite (MMT), fluorohectorite, kaolinite (also known as kaolin) vermiculite, illite, mica, or brittle mica, which can be used in the present invention. In particular, it is preferable to use montmorillonite in the present invention.

The montmorillonite has a structure in which Mg ²⁺ , Fe ²⁺ , and Fe ³⁺ ions are substituted for Al ³⁺ ions in the alumina octahedral sheet, and Al ³⁺ ions are substituted for Si ⁴⁺ ions in the silicate tetrahedron sheet, Resulting in a negative charge as a whole. It also contains exchangeable cation and water molecules between the silicate layers to balance the charge as a whole.

The aspect ratio of the short axis to the major axis of the silicate is preferably 1/30 to 1/1000, more preferably 1/100 to 1/800, most preferably 1/500 to 1/800 Do. When the ratio of the short axis to the long axis of the silicate is larger than 1/30, the peeled silicate does not act as the diffusion barrier of the gas and the liquid, and the resolution is remarkably lowered, which is not preferable. If the ratio of the short axis to the long axis of the silicate is less than 1/1000, it is difficult to peel off due to the penetration of the cation exchange resin chains, and as a result, it is difficult to disperse in the cation exchange resin in the resulting polymer electrolyte membrane.

The long axis length of the silicate is preferably 0.05 to 0.5 mu m, more preferably 0.05 to 0.2 mu m. When the major axis length of the silicate is less than 0.05 탆, the plate-like structure is not formed and the effect of blocking the hydrocarbon fuel is reduced. When the major axis length is larger than 0.5 탆, penetration into the pores of the support is difficult.

In addition, when the layered structure of the silicate is peeled off, the distance between the silicate layers is preferably at least 3 nm. The silicate interlayer distance refers to the time when the polymer chain penetrates the silicate plate and peels off between the layer and the layer. At least 3 nm, the polymer chain gradually penetrates and the gap between the layer and the layer gradually widens and the silicate layer becomes disordered If it is dispersed, it is not appropriate to define the distance between the layers and the layer, so the distance between them can not be measured. Therefore, the interlayer distance should be at least 3 nm, and the maximum value is meaningless.

It is preferable that the silicate is treated with an organizing agent. When such an organizing agent is used, it is difficult to remove the silicate between the platy silicate layer structure, which is difficult to peel and disperse in the polymer resin due to strong van der Waals attractive force. An organic agent having a molecular weight is inserted to easily penetrate the polymer resin, which facilitates peeling and dispersion.

As the organizing agent, an alkylamine having 1 to 20 carbon atoms, an alkylenediamine having 1 to 20 carbon atoms, a quaternary ammonium salt having 1 to 20 carbon atoms, an aminohexane or a nitrogen-containing heterocyclic compound can be used.

Specific examples of the alkylamine include methylamine hydrochloride, propylamine, butylamine, octylamine, decylamine, dodecylamine, hexadecylamine, octadecylamine, N-methyloctadecylamine, and the like.

Examples of the alkylenediamine include 1,6-hexamethylenediamine and 1,12-dodecanediamine.

Examples of the quaternary ammonium salt include dimethyl quaternary ammonium, benzyl quaternary ammonium, 2-ethylhexyl quaternary ammonium, bis-2-hydroxyethyl quaternary ammonium, methyl quaternary ammonium, tetramethylammonium chloride, octadecyltrimethylammonium bromide , Dodecyltrimethylammonium bromide, dioctadecyldimethylammonium bromide, bis (2-hydroxyethyl) methyloctadecylammonium chloride, and the like can be used.

As the aminohexane, 6-aminohexane, 12-aminohexane and the like can be used, and as the nitrogen-containing heterocyclic compound, 1-hexadecylpyridinium chloride and the like can be used.

The silicate may be used by treating with the above-mentioned organizing agent, but it is also possible to directly use the organically treated silicate. Examples of organically treated silicates include Cloisite 6A, Cloisite 10A, Cloisite 15A, Cloisite 20A, Cloisite 25A, Cloisite 30B and the like as trade names of Southern Corporation.

As the cation exchange resin preferred in the present invention, any cationic polymer resin having hydrogen ion conductivity can be used. Representative examples thereof include a polymer resin having a cation-exchange group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group and derivatives thereof in the side chain. It is also possible to substitute -SO ₃ H, -COOH, -HPO ₃ H, and -H in -POOH with monovalent ions such as sodium, potassium, cesium and tetrabutylammonium (TBA) in the ion exchanger at the end of the side chain have.

Representative examples of the polymer resin include fluorine-based polymers, benzimidazole-based polymers, polyimide-based polymers, polyetherimide-based polymers, polyphenylene sulfide-based polymers, polysulfone-based polymers, polyether sulfone-based polymers, (Perfluorosulfonic acid), poly (perfluorocarboxylic acid), poly (perfluorocarboxylic acid), poly (perfluorocarboxylic acid), and poly Copolymers of tetrafluoroethylene and fluorovinyl ethers containing sulfonic acid groups, dehydrofluorinated sulfated polyether ketones, aryl ketones, poly (2,2'-m-phenylene) -5,5'-bibenzimidazole (poly (2,2 '- (m-phenylene) -5,5'-bibenzimidazole) or poly (2,5-benzimidazole).

In the present invention, the mixing ratio of the cation exchange resin and the silicate is preferably 98 to 90: 2 to 10 weight ratio. When the amount of the silicate used is less than the above range, the effect of using the silicate is insufficient. When the amount of the silicate is more than the above range, there is a problem that the mixing is difficult due to the aggregation of the silicates when mixed with the cation exchange resin.

The membrane-electrode assembly for a fuel cell including the polymer electrolyte membrane of the present invention includes an anode electrode and a cathode electrode respectively disposed on both sides of the polymer electrolyte membrane.

The cathode electrode and the anode electrode include an electrode substrate and a catalyst layer.

The catalyst layer may be formed of one selected from the group consisting of platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy and platinum-M alloy (M is Ga, Ti, V, Cr, Mn, Fe, And at least one transition metal selected from the group consisting of a transition metal oxide and a transition metal oxide.

Such a metal catalyst may be used as a metal catalyst itself (black) or may be supported on a carrier. Carbon such as acetylene black, denka black, activated carbon, ketjen black and graphite may be used as the carrier, or inorganic fine particles such as alumina, silica, titania and zirconia may be used, but carbon is generally widely used.

The electrode substrate plays a role of supporting the electrode and diffusing the fuel and the oxidant into the catalyst layer so that the fuel and the oxidant can easily access the catalyst layer. As the electrode substrate, a conductive substrate is used. Typical examples of the electrode substrate include a porous film or polymer composed of a carbon paper, a carbon cloth, a carbon felt, or a metal cloth But is not limited to, a metalized polymer fiber formed on the surface of a fabric formed of fibers).

Also, it is preferable that the electrode substrate is subjected to a water repellent treatment with a fluorine-based resin, because it is possible to prevent the gas diffusion efficiency from being lowered by water generated when the fuel cell is driven. Examples of the fluorine-based resin include polyvinylidene fluoride, polytetrafluoroethylene, polyfluoroethylene propylene, fluorinated ethylene propylene, polychlorotrifluoroethylene, fluoroethylene Polymers and the like can be used.

The microporous layer may further include a microporous layer for enhancing the gas diffusion effect in the electrode substrate. The microporous layer is generally composed of a conductive powder having a small particle diameter such as carbon powder, carbon black, acetylene black, activated carbon, carbon fiber, fullerene, carbon nanotube, carbon nanowire, carbon nano -horn) or a carbon nano ring. The microporous layer is prepared by coating a composition comprising conductive powder, a binder resin and a solvent on the gas diffusion layer. As the binder resin, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl alcohol, cellulose acetate and the like can be preferably used. As the solvent, ethanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol and the like Alcohols, water, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone and the like can be preferably used. The coating process may be performed by a screen printing method, a spray coating method or a coating method using a doctor blade, depending on the viscosity of the composition, but is not limited thereto.

The fuel cell system of the present invention includes at least one electricity generating portion, a fuel supplying portion and an oxidizing agent supplying portion.

The electricity generating portion includes a membrane-electrode assembly and a separator (also referred to as a bipolar plate). The membrane-electrode assembly includes a polymer electrolyte membrane and cathode and anode electrodes present on both sides of the polymer electrolyte membrane. The electricity generating unit generates electricity through the oxidation reaction of the fuel and the reduction reaction of the oxidant.

The fuel supply unit supplies fuel to the electricity generation unit, and the oxidant supply unit supplies an oxidant such as oxygen or air to the electricity generation unit.

In the present invention, the fuel may include hydrogen or a hydrocarbon fuel in a gaseous or liquid state. Representative examples of the hydrocarbon fuel include methanol, ethanol, propanol, butanol or natural gas. The present invention is more suitable for a direct oxidation fuel cell system using a hydrocarbon fuel, and is most suitable for a passive type fuel cell system that supplies a fuel of a high concentration in a diffusion manner. In the present invention, a hydrocarbon fuel having a concentration of 1 to 10 M can be used.

A schematic structure of the fuel cell system of the present invention is shown in FIG. 2 and will be described in detail with reference to the following. The structure shown in FIG. 2 shows a system for supplying the fuel and the oxidant to the electricity generating unit using a pump. However, the fuel cell system of the present invention is not limited to such a structure, and may be a fuel cell using a diffusion- It is natural that it can be used in a system structure.

  The fuel cell system 100 of the present invention includes at least one electricity generating unit 19 for generating electric energy through oxidation reaction of a fuel and oxidizing agent, a fuel supply unit 1 for supplying the fuel, And an oxidant supplier (5) for supplying an oxidant to the electricity generator (19).

Further, the fuel supply unit 1 for supplying the fuel has a fuel tank 9 for storing the fuel. And may further include a fuel pump 15 for supplying fuel to the electricity generating portion.

The oxidant supply part 5 for supplying the oxidant to the electricity generating part 19 includes at least one oxidant pump 13 for sucking the oxidant with a predetermined pumping power.

The electricity generating unit 19 is composed of a membrane-electrode assembly 21 for oxidizing and reducing the fuel and an oxidizing agent, and bipolar plates 23 and 25 for supplying fuel and oxidant to both sides of the membrane- , And at least one such electricity generating portion 19 is gathered to constitute the stack 7.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described. However, the following examples are only illustrative of the present invention and are not intended to limit the scope of the present invention.

(Example 1)

Montmorillonite (Southern Clay Products, CLoisite 10A) and 1,3-propane sultone were mixed in dry toluene, and the mixture was stirred at 100 ° C for 24 hours. Then, the obtained product was filtered, the filtrate was washed with toluene and dried for 24 hours to prepare montmorillonite having a sulfonic acid group bonded at its end.

A solution of perfluorosulfonate resin (5 wt% Nafion / H ₂ O / 2-propanol, Solution Technology Inc., EW = 1,100) dissolved in commercially available water and 2-propanol was forcedly evaporated at room temperature Then, the solution was added to dimethylacetamide in a concentration of 5% by weight and stirred at 100 ° C for 24 hours to dissolve the cation exchange resin to prepare a cation exchange resin solution.

(Southern Clay Product, Cloisite 10A) having a sulfonic acid group bonded thereto, an aspect ratio of 1/500 (at fully intercalated state, a long axis length of about 0.3 탆 ) Was added, and the mixture was mixed with a magnetic stirrer at 100 ° C for 24 hours. Ultrasonic waves were applied to the mixture to form a cation exchange resin chain between the montmorillonite layers to prepare a silicate-peeled resin composition. At this time, the separation distance between the montmorillonite layers was 3 nm or more. The mixing ratio of the cation exchange resin to the montmorillonite having a sulfonic acid group was 98% by weight and 2% by weight.

The resin composition was applied to a glass plate in an oven at about 100 캜 to prepare a polymer electrolyte membrane.

(TBA ⁺ ) -formed Nafion was prepared by mixing Pt-Ru black (Johnson Matthey HiSpec 6000, 4.0 mg / cm ² ) anode catalyst and Pt black (Tanaka Kikinzoku Kogyo, 4.0 mg / cm ² ) An anode and a cathode catalyst slurry were respectively prepared, and this catalyst slurry was applied to a 50 mu m-thick Teflon-fluoroethylene propylene carbon paper sheet to prepare an anode electrode and a cathode electrode, respectively.

The polymer electrolyte membrane was placed between the anode and the cathode, and then hot-pressed at 195 DEG C and 500 psig for 1 minute to prepare a membrane-electrode assembly.

(Example 2)

The procedure of Example 1 was repeated, except that the amount of montmorillonite having a cation exchange resin and a sulfonic acid group was changed to 95% by weight and 5% by weight.

(Example 3)

The procedure of Example 1 was repeated except that the amount of montmorillonite having a cation exchange resin and a sulfonic acid group was changed to 90% by weight and 10% by weight.

(Example 4)

The procedure of Example 1 was repeated, except that the amount of montmorillonite having a cation exchange resin and a sulfonic acid group was changed to 99 wt% and 1 wt%.

(Example 5)

The procedure of Example 1 was repeated except that the amount of montmorillonite having a cation exchange resin and a sulfonic acid group was changed to 97 wt% and 3 wt%.

(Example 6)

The procedure of Example 1 was repeated, except that fluorohectolite (CO OP CHEMICAL CP., LTD.) Was used instead of montmorillonite.

(Example 7)

The procedure of Example 2 was repeated except that fluorohectolite (CO OP CHEMICAL CP., LTD.) Was used instead of montmorillonite.

(Example 8)

The procedure of Example 3 was repeated, except that fluorohectolite (CO OP CHEMICAL CP., LTD.) Was used in place of montmorillonite.

(Example 9)

The procedure of Example 1 was repeated except that kaolin (Aldrich) was used instead of montmorillonite.

(Example 10)

The procedure of Example 2 was repeated except that kaolin (Aldrich) was used instead of montmorillonite.

(Example 11)

The procedure of Example 3 was repeated except that kaolin (Aldrich) was used instead of montmorillonite.

(Comparative Example 1)

A solution of perfluorosulfonate resin (5 wt% Nafion / H ₂ O / 2-propanol, Solution Technology Inc., EW = 1,100) dissolved in commercially available water and 2-propanol was placed in an oven To a glass plate to prepare a polymer electrolyte membrane.

(Reference Example 1)

A solution of perfluorosulfonate resin (5 wt% Nafion / H ₂ O / 2-propanol, Solution Technology Inc., EW = 1,100) dissolved in commercially available water and 2-propanol was forcedly evaporated at room temperature Then, the solution was added to dimethylacetamide in a concentration of 5% by weight and stirred at 100 ° C for 24 hours to dissolve the cation exchange resin to prepare a cation exchange resin solution.

(Southern Clay Product, Cloisite 10A) treated with an organizing agent, an aspect ratio of 1/500 (at fully intercalated state, long axis length: about 0.3 탆 ) Was added at a ratio of 99% by weight of the cation-exchange resin and 1% by weight of the inorganic additive, and the resultant mixture was mixed with a magnetic stirrer at 100 ° C for 24 hours. Ultrasonic waves were applied to the montmorillonite layer, To thereby prepare a resin composition in which the silicate has been peeled off. At this time, the separation distance between the montmorillonite layers was 3 nm or more.

A polymer electrolyte membrane was prepared using the above resin composition by a conventional method, and a membrane-electrode assembly was produced in the same manner as in Example 1 using this polymer electrolyte membrane.

(Reference Example 2)

The procedure of Reference Example 1 was repeated except that the amount of the cation exchange resin used was changed to 98 wt% and the amount of montmorillonite was changed to 2 wt%.

(Reference Example 3)

The procedure of Reference Example 1 was repeated except that the amount of the cation exchange resin used was changed to 97 wt% and the amount of the montmorillonite was changed to 3 wt%.

(Reference Example 4)

The procedure of Reference Example 1 was repeated except that the amount of the cation exchange resin used was changed to 95 wt% and the amount of the montmorillonite was changed to 5 wt%.

(Reference Example 5)

The procedure of Reference Example 1 was repeated except that the amount of the cation exchange resin used was changed to 93 wt% and the amount of the montmorillonite was changed to 7 wt%.

(Reference Example 6)

The procedure of Reference Example 1 was repeated except that the amount of the cation exchange resin used was changed to 90% by weight and the amount of montmorillonite was changed to 10% by weight.

* Evaluation of Physical Properties of Polymer Electrolyte Membrane

The tensile strength, water uptake, thickness variation and dimensional change (area change) of the polymer electrolyte membrane prepared according to Examples 1 to 3, Examples 6 to 11 and Comparative Example 1 were measured The results are shown in Table 1. The water absorption rate, thickness variation and dimensional change were measured in a dry state (after the polyelectrolyte membrane was dried at 120 ° C for 24 hours) and in dehumidified water (deionized water) for 24 hours .

The tensile strength was measured according to ASTM using an instron mechanical test machine.

Tensile Strength (MPa) Water Absorption Rate (%) Thickness change (%) Dimensional change (%) Comparative Example 1 40.0 21.8 18.4 16.6 Example 1 30.6 21.5 9.1 11.4 Example 2 23.4 58.4 7.0 17.4 Example 3 Do not measure 79.4 13.9 14.5 Example 6 44.8 36.1 6.3 11.8 Example 7 43.6 50.3 7.9 4.3 Example 8 42.0 56.6 10 5.3 Example 9 43.1 10.4 2.5 7.6 Example 10 42.5 39.7 9.8 13.8 Example 11 38.2 58.6 15.2 11.9

As shown in Table 1, the water absorption rates of the polymer electrolyte membranes of Examples 1 to 8 and Examples 10 to 11 are superior to those of Comparative Example 1. The water absorption rate of the polymer electrolyte membrane is closely related to the hydrogen ion conductivity which affects the physical properties of the battery. From the results of the above Table 1, the hydrogen ion conductivity of the polymer electrolyte membranes of Examples 1 to 8 and Examples 10 to 11 is shown in Comparative Example 1 It can be predicted that it will be excellent. It is considered that the polymer electrolyte membrane of Example 9 has a somewhat lower water absorption rate of kaolin itself and a smaller amount of water to be used than Comparative Example 1.

It can also be seen that the thickness variation and the dimensional change of all the polymer electrolyte membranes of Examples 1 to 11 are smaller or almost equal to those of Comparative Example 1. [

* X-ray diffraction peak measurement of polymer electrolyte membrane

X-ray diffraction peaks of the polymer electrolyte membranes of Examples 1 to 3 were measured to see whether the cation exchange resin and the silicate were uniformly dispersed in the polymer electrolyte membranes of Examples 1 to 3, and the results are shown in Fig. 3 . For reference, the X-ray diffraction peaks of montmorillonite (MMT in FIG. 3) and montmorillonite having a sulfonic acid group at the end prepared in Example 1 (S-MMT in FIG. 3) Are shown together in Fig.

The X-ray diffraction peak was measured using a CuK? Ray (? = 1.5406?) Using an X-ray diffractometer (Phillips, X'pert Pro X-ray). In the results of FIG. 3, MMT and S-MMT are crystalline and thus show peaks. In Examples 1 to 3, it can be predicted that the cation exchange resin is inserted into a silicate plate having sulfonic acid groups. As a result, the distance between the silicate plate phases is increased as compared with Comparative Example 2 using only silicate, and the silicate is peeled in the cation exchange resin to induce a strong interaction between the cation exchange resin and the silicate to improve the mechanical strength have.

* Measurement of methanol permeability

The methanol permeability of the polymer electrolyte membranes of Examples 1 to 3, Examples 6 to 10, and Comparative Example 1 was measured, and the results are shown in FIG.

4, "" indicates a result of a polymer electrolyte membrane prepared using montmorillonite (S-MMT) in which Nafion and sulfonic acid groups are bonded in Examples 1 to 3, " (S-FHT) in which Nafion and sulfonic acid groups are bonded to each other, and "" represents the results of kaolin bonded with Nafion and sulfonic acid groups in Examples 9 to 10 S-kaolin). ≪ / RTI > In addition, the X-axis represents amounts of silicate addition such as S-MMT, S-FHT and S-kaolin.

As shown in FIG. 4, the methanol permeability of Examples 1 to 3 and 6 to 10 is remarkably lower than that of Comparative Example 1. It is believed that this is because the silicate sheet effectively prevents the pathway of methanol in the polymer electrolyte membrane. As shown in FIG. 5, in which hydrogen ion conductivity was measured while varying the amount of montmorillonite added, Examples 1, 2, and 4, in which sulfonic acid groups were bonded at the terminals, compared to Reference Examples 1 to 6 using pure silicate And 5 of the polymer electrolyte membrane showed excellent hydrogen ion conductivity. 5 shows the hydrogen ion conductivity of the polyelectrolyte membrane prepared only with Nafion in Comparative Example 1, and the symbol ◯ indicates the polymer electrolyte prepared using Nafion and S-MMT of Examples 1, 2, 4, and 5 Shows the hydrogen ion conductivity of the membrane, and the symbol &thetas; shows the hydrogen ion conductivity of the polymer electrolyte membrane prepared using the Nafion and MMT of Reference Examples 1 to 6. [ The X-axis represents the amount of MMT added.

* Battery characteristics

The fuel cell system using the polymer electrolyte membrane of Example 2 was supplied with dry air as an oxidizer and methanol as a fuel at 3M, 4M, 5M and 7M, and the output density at 70 ° C was measured. The results are shown in FIG. The fuel cell system using the polymer electrolyte membrane of Comparative Example 1 was also supplied with dry air as an oxidant and methanol as a fuel at 3M and 7M, and the output density at 70 ° C was measured. The results are shown in FIG. As shown in FIGS. 6 and 7, the fuel cell system using the polymer electrolyte membrane of Example 2 is superior to that of Comparative Example 1, even when methanol at a high concentration is injected.

Therefore, the polymer electrolyte membrane of the present invention can be effectively used in a passive type fuel cell system in which fuel is injected in a diffusion manner by using methanol at a high concentration.

INDUSTRIAL APPLICABILITY The polymer electrolyte membrane of the present invention is excellent in hydrogen ion conductivity and excellent in the effect of preventing crossover of fuel, so that a fuel cell system exhibiting excellent cell performance can be provided.

Claims (20)

Cation exchange resins; And A silicate having a proton conductive group at the terminal Lt; / RTI > The mixing ratio of the cation exchange resin to the silicate is 98 to 90: 2 to 10, The silicate has a major axis length of 0.05 to 0.5 mu m, Passive type polymer electrolyte membrane for direct oxidation type fuel cells. The method according to claim 1, Wherein the hydrogen ion conductive group is a sulfonic acid group. The method according to claim 1, The silicate may be selected from the group consisting of pyrophyllite-talc, montmorilonite (MMT), fluorohectorite, kaolinite, vermiculite, illite, mica, and brittle mica. The polymer electrolyte membrane for passive type direct oxidation fuel cells according to claim 1, wherein the polymer electrolyte membrane is selected from the group consisting of mica and brittle mica. The method according to claim 1, Wherein the cation exchange resin is a polymer resin having a cation exchanger selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, and derivatives thereof in a side chain. 5. The method of claim 4, The cation exchange resin may be at least one selected from the group consisting of a fluoro polymer, a benzimidazole polymer, a polyimide polymer, a polyetherimide polymer, a polyphenylene sulfide polymer, a polysulfone polymer, a polyether sulfone polymer, , A polyether-ether ketone-based polymer, and a polyphenylquinoxaline-based polymer. The polymer electrolyte membrane for passive type direct oxidation type fuel cells, The method according to claim 1, Wherein the silicate has an aspect ratio of 1/30 to 1/1000. ≪ RTI ID = 0.0 > 11. < / RTI > delete The method according to claim 1, Wherein the silicate has a delaminated layered structure and the distance between each layer is 3 nm or more. The method according to claim 1, Wherein the silicate is a silicate treated with an organizing agent, the polymer electrolyte membrane for a direct oxidation type fuel cell. 10. The method of claim 9, Wherein the organic agent is selected from the group consisting of alkyl amines having 1 to 20 carbon atoms, alkylenediamines having 1 to 20 carbon atoms, quaternary ammonium having 1 to 20 carbon atoms, alkylammonium salts having 1 to 20 carbon atoms, aminohexane and nitrogen-containing heterocyclic compounds Wherein the polymer electrolyte membrane is a polymer electrolyte membrane. delete An anode electrode, a cathode electrode, The polymer electrolyte membrane according to any one of claims 1 to 6 and 8 to 10, Electrode assembly for a direct oxidation type fuel cell. delete delete Electrode assembly and a separator comprising an anode electrode and a cathode electrode facing each other and a polymer electrolyte membrane according to any one of claims 1 to 6 and 8 to 10, At least one electricity generating unit for generating electricity through a reduction reaction of the oxidant; A fuel supply unit for supplying fuel to the electricity generation unit; And And an oxidant supplier for supplying an oxidant to the electricity generator, Passive type direct oxidation fuel cell system. delete delete 16. The method of claim 15, Wherein the fuel is hydrogen or hydrocarbon fuel in liquid or gaseous state. 19. The method of claim 18, Wherein the hydrocarbon fuel is selected from the group consisting of methanol, ethanol, butanol, and isopropanol. 20. The method of claim 19, Wherein the hydrocarbon fuel has a concentration of 3 to 10 M. 5. A direct oxidation fuel cell system according to claim 1,

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