WO2011021870A2 - Macromolecular electrolyte film for a macromolecular electrolyte type of fuel cell, a production method for the same and a macromolecular electrolyte type of fuel cell system comprising the same - Google Patents

Abstract

The present invention relates to a macromolecular electrolyte film for a macromolecular electrolyte type of fuel cell, to a production method for the same and to a macromolecular electrolyte type of fuel cell system comprising the same; wherein the macromolecular electrolyte film comprises a hydrocarbon-based hydrogen-ion-conducting macromolecular film, and the surface contact angle of the macromolecular film is from 80 degrees (°) to 180 degrees (°).

Description

Polymer electrolyte membrane for polymer electrolyte fuel cell, manufacturing method thereof and polymer electrolyte fuel cell system comprising same

The present disclosure relates to a polymer electrolyte membrane for a polymer electrolyte fuel cell, a method of manufacturing the same, and a polymer electrolyte fuel cell system including the same.

A fuel cell is a power generation system that directly converts the chemical reaction energy of hydrogen and oxygen contained in hydrocarbon-based materials such as methanol, ethanol and natural gas into electrical energy.

This fuel cell is a clean energy source that can replace fossil energy, and has the advantage of generating a wide range of outputs by stacking unit cells, and having an energy density of 4-10 times that of a small lithium battery. It is attracting attention as a compact and mobile portable power source.

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

In such fuel cell systems, the stack that substantially generates electricity may comprise several to several unit cells consisting of a membrane-electrode assembly (MEA) and a separator (also called a bipolar plate). It has a stacked structure of ten. The membrane-electrode assembly is called an anode electrode (also called "fuel electrode" or "oxidation electrode") and a cathode electrode (also called "air electrode" or "reduction electrode") with a polymer electrolyte membrane containing a hydrogen ion conductive polymer therebetween. ) And the polymer electrolyte membrane has a structure that is bonded to the anode electrode and the cathode electrode through a binder having a hydrogen ion conductivity.

The principle of generating electricity in a fuel cell is that fuel is supplied to an anode electrode, which is a fuel electrode, adsorbed to a catalyst of the anode electrode, and the fuel is oxidized to generate hydrogen ions and electrons, wherein the generated electrons are an external circuit having electrical conductivity. As a result, the anode reaches the cathode, which is an anode, and hydrogen ions are transferred to the polymer electrolyte membrane through a binder having hydrogen ion conductivity, and then passed through the binder to the cathode electrode. An oxidant is supplied to the cathode, and the oxidant, hydrogen ions, and electrons react on the catalyst of the cathode to generate electricity while producing water.

One embodiment of the present invention to provide a polymer electrolyte membrane for a polymer electrolyte fuel cell that can improve the performance of the fuel cell.

Another embodiment of the present invention is to provide a method for producing the polymer electrolyte membrane.

Another embodiment of the present invention is to provide a polymer electrolyte fuel cell system including the polymer electrolyte membrane.

The polymer electrolyte membrane for a polymer electrolyte fuel cell according to an embodiment of the present invention includes a hydrocarbon-based hydrogen ion conductive polymer membrane, and the surface contact angle of the polymer electrolyte membrane may be 80 degrees (°) to 180 degrees (°). The surface contact angle of the polymer electrolyte membrane may exhibit weak hydrophobicity of 80 degrees (°) or more and less than 120 degrees (°).

The hydrocarbon-based hydrogen ion conductive polymer is a polymer having a hydrogen ion conductive group, the polymer is a benzimidazole-based polymer, benzoxazole-based polymer, polyimide-based polymer, polyetherimide-based polymer, polyphenylene sulfide-based polymer, poly Hydrocarbon polymer selected from the group consisting of sulfone polymer, polyether sulfone polymer, polyether ketone polymer, polyether-ether ketone polymer, polyphenylquinoxaline polymer, copolymers thereof, and combinations thereof Can be.

According to another embodiment of the present invention, there is provided a surface treatment method of a polymer electrolyte membrane for a polymer electrolyte fuel cell, including a step of hydrophobic treatment of a hydrocarbon-based hydrogen ion conductive polymer membrane using plasma.

At this time, the hydrophobic treatment using the plasma is a first gas selected from argon gas, nitrogen gas, oxygen gas, helium gas or a combination thereof, and a second gas selected from a hydrocarbon gas, a fluorocarbon gas or a combination thereof. This can be done while blowing.

The hydrocarbon gas may be CH ₄ or C ₂ H ₂ , the fluorocarbon gas may be C ₄ F ₈ , CF ₄ or a combination thereof.

In one embodiment of the invention, the plasma treatment is selected from the group consisting of a first gas selected from argon, nitrogen, oxygen, helium and combinations thereof, and CF ₄ , C ₄ F ₈ gas and combinations thereof This can be done while blowing the second gas.

According to another embodiment of the present invention, at least one electricity generating unit for generating electricity through an oxidation reaction of the fuel and a reduction reaction of the oxidant, a fuel supply unit for supplying fuel to the electricity generating unit and an oxidant to the electricity generating unit Provided is a fuel cell system comprising an oxidant supply unit for supplying.

The electricity generating unit includes an anode electrode and a cathode electrode positioned opposite each other, and at least one membrane-electrode assembly and a separator including a polymer electrolyte membrane positioned between the anode electrode and the cathode electrode.

The polymer electrolyte membrane may be bonded to a binder included in an anode electrode and a cathode electrode.

The polymer electrolyte membrane has a first surface in contact with the anode electrode and a second surface in contact with the cathode electrode, and the contact angle of the first surface or the second surface is 80 degrees (°) to 180 degrees (°). Can be. In addition, the contact angle of the first surface or the second surface may be greater than 80 degrees (°), less than 120 degrees (°). In addition, the contact angle of the second surface may be 80 degrees (°) to 180 degrees (°), and both the first and second surfaces may be 80 degrees (°) to 180 degrees (°).

The polymer electrolyte membrane according to an embodiment of the present invention is excellent in dimensional stability while maintaining the moisture content inside the membrane, and at the same time improve the physical properties of the fuel cell, and improves the bonding with the binder, in particular commercially widely used fluorine-based The adhesion to the binder can be increased, thereby improving the electrochemical performance and long-term performance of the manufactured membrane-electrode assembly.

1 is a view showing a bonding state of a polymer electrolyte membrane and an electrode according to an embodiment of the present invention.

2 schematically illustrates the structure of a fuel cell system according to an embodiment of the invention.

3 is a graph showing the water content of the polymer electrolyte membranes of Examples 1 and 2 and Comparative Examples 1 and 2;

Figure 4 is a graph showing the measurement of the dimensional stability of the polymer electrolyte membrane of Examples 1 and 2 and Comparative Examples 1 and 2.

5 is a graph showing the cell performance of the unit cell prepared using the polymer electrolyte membrane of Examples 1 to 2 and Comparative Example 1.

Figure 6 is a graph showing the cell performance of the unit cells prepared according to Examples 6 to 8 and Comparative Examples 3 and 9 measured at 100% relative humidity.

7 is a graph showing the cell performance of the unit cells prepared according to Examples 6 to 8 and Comparative Example 3 measured under a relative humidity of 65%.

FIG. 8 is a graph showing the cell performance of unit cells prepared according to Examples 6 to 8 and Comparative Example 3, measured at 45% relative humidity, and showing the results.

Figure 9 is a graph showing the cell performance of the unit cells prepared according to Comparative Example 3, Comparative Examples 6 to 9 measured at 100% relative humidity conditions.

10 is a graph showing the cell performance of unit cells prepared according to Comparative Example 3 and Comparative Examples 6 to 8 at 65% relative humidity.

11 is a graph showing the cell performance of unit cells prepared according to Comparative Example 3 and Comparative Examples 6 to 8 at 45% relative humidity.

12 is a graph showing the cell performance of the unit cell of Comparative Example 12 measured at a temperature of 70 ° C. and various relative relative humidity conditions.

FIG. 13 is a graph showing the cell performance of the unit cell of Comparative Example 13 measured at a temperature of 70 ° C. and various relative relative humidity conditions. FIG.

14 is a graph showing the cell performance of the unit cell of Comparative Example 14 measured at a temperature of 70 ° C. and various relative relative humidity conditions.

15 is a graph showing the cell performance of the unit cell of Comparative Example 15 measured at 70 ° C. and various relative relative humidity conditions.

FIG. 16 is a graph showing the battery performance of a unit cell of Comparative Example 12 measured at a temperature of 80 ° C. and various relative relative humidity conditions. FIG.

17 is a graph showing the cell performance of the unit cell of Comparative Example 13 measured at a temperature of 80 ° C. and various relative relative humidity conditions.

18 is a graph showing the cell performance of the unit cell of Comparative Example 14 measured at a temperature of 80 ° C. and various relative relative humidity conditions.

19 is a graph showing the cell performance of the unit cell of Comparative Example 15 measured at a temperature of 80 ° C. and various relative relative humidity conditions.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

The polymer electrolyte membrane for a polymer electrolyte fuel cell according to an embodiment of the present invention is a polymer membrane formed of a hydrocarbon-based hydrogen ion conductive polymer. The polymer electrolyte membrane may have a hydrophobicity of a contact angle of 80 degrees (°) to 180 degrees (°). In addition, the surface contact angle of the polymer electrolyte membrane may be weak hydrophobicity of more than 80 degrees (°), less than 120 degrees (°).

If the contact angle of the polymer electrolyte membrane is less than 80 degrees (°), due to excessive expansion of the polymer electrolyte membrane during hydration, there may be a disadvantage that the problem of separation with the catalyst layer containing the binder may occur.

As such, when the surface contact angle of the polymer electrolyte membrane shows hydrophobicity of 80 degrees (°) to 180 degrees (°), the adhesion between the anode and the cathode electrode with the catalyst layer may be excellent. The effect of excellent bonding can be maximized when using a fluorine-based binder. The bonding between the catalyst layer of the anode and the cathode electrode and the polymer electrolyte membrane is mainly carried out through a binder included in the catalyst layer, and since the commonly used binder shows hydrophobicity as a fluorine resin, it is very compatible with the surface of the polymer electrolyte showing hydrophobicity. This is because bonding can be further improved. As such, when the adhesion between the catalyst layer of the electrode and the polymer electrolyte membrane is excellent, long-term stability of the fuel cell may be improved.

In the present invention, when the total thickness of the polymer electrolyte membrane is 100%, the surface is about 10% from the outermost surface (surface in contact with the anode electrode or the cathode electrode) of the polymer electrolyte membrane in the depth (direction toward the opposite electrode) direction. It means the depth to. The surface may mean a depth of up to about 5% from the outermost surface of the polymer electrolyte membrane.

That is, the polymer electrolyte membrane according to one aspect of the present invention is controlled only to the hydrophobicity (for example, weak hydrophobicity or superhydrophobic) of the physical properties of the surface, the physical properties of the inside is to maintain the physical properties of the polymer electrolyte membrane itself. If the internal properties of the polymer electrolyte membrane also have the same hydrophobicity as the surface, the hydrogen ion conductivity is lowered, which is not good.

As such, the contact angle of the surface of the polymer electrolyte membrane in contact with the electrode may exhibit hydrophobicity of 80 degrees (°) to 180 degrees (°). Hydrophobicity may be referred to as weak hydrophobicity in the case of more than 80 degrees and less than 120 degrees, depending on the contact angle, and may be referred to as hydrophobicity in the case of 120 to 180 degrees. In one embodiment of the present invention, the contact angle of the surface of the polymer electrolyte membrane may be more appropriate than the weak hydrophobicity of more than 80 degrees (°), less than 120 degrees (°).

When the contact angle of the surface of the polymer electrolyte membrane is 80 degrees (°) to 180 degrees (°), it has excellent adhesion with the binder used in the catalyst layer, especially the fluorine-based binder generally used in the catalyst layer, thereby lowering the interface resistance between the electrode and the electrolyte membrane. In addition, the dimensional stability is improved to reduce the peeling phenomenon with the catalyst layer including the binder, there is an advantage that can improve the electrochemical performance and long-term stability. In particular, when the contact angle of the surface of the polymer electrolyte membrane exhibits weak hydrophobicity of 80 degrees (°) or more and less than 120 degrees (°), the output density improvement effect of the fuel cell is more excellent.

The hydrocarbon-based hydrogen ion conductive polymer may be any hydrocarbon-based polymer resin having hydrogen ion conductivity, in particular a cation selected from the group consisting of sulfonic acid groups, carboxylic acid groups, phosphoric acid groups, phosphonic acid groups and derivatives thereof in the side chain. Any hydrocarbon-based polymer resin having an exchange group can be used. Examples thereof include benzimidazole polymer, benz oxide polymer, polyimide polymer, polyetherimide polymer, polyphenylene sulfide polymer, polysulfone polymer, polyether sulfone polymer, polyether ketone polymer, poly Hydrocarbon-based polymers selected from ether-etherketone-based polymers or polyphenylquinoxaline-based polymers, copolymers thereof, or a combination thereof can be used.

Specific examples of the polymer resin include polyether ether ketone, polypropylene oxide, polyacrylic acid-based ionomer, polyarylene ether sulfone), sulfonated poly arylene ether sulfone, sulfonated poly ether ether ketone, sulfonated poly phosphazene, sulfonate Fonated poly arylene sulfide, sulfonated poly arylene sulfide sulfide, poly benzoxazole, poly (2,2'-m-phenylene) -5,5'-bibenzimidazole [poly (2,2'-m -phenylene) -5,5'-bibenzimidazole] or poly (2,5-benzimidazole) can be used. Of course, the polymer resin has a cation exchange group described above in the side chain.

The effect of controlling the surface of the polymer electrolyte membrane according to one embodiment of the present invention to hydrophobicity, it may be better to use a hydrocarbon-based polymer as a hydrogen ion conductive polymer, compared to using a fluorine-based polymer.

In the fuel cell, the electrode including the polymer electrolyte membrane and the catalyst layer formed on the electrode substrate is brought into contact with the electrode through the binder of the catalyst layer of the electrode, as shown in FIG. In this case, the polymer electrolyte membrane composed of a hydrocarbon-based polymer is not compatible with the binder of the catalyst layer, in particular, the fluorine-based binder, so that the separation of the layer between the electrolyte membrane and the electrode may occur better than when the polymer electrolyte membrane composed of the fluorine-based polymer is used. . By controlling the layer separation problem to have a hydrophobicity similar to that of the fluorine-based binder of the catalyst layer, the compatibility of the polymer electrolyte membrane with the catalyst layer of the electrode can be further improved by controlling the surface of the polymer electrolyte membrane similarly to the fluorine-based binder of the catalyst layer. It can be very large in a polymer electrolyte membrane composed of a hydrocarbon-based polymer.

In the hydrogen ion conductive group of the hydrogen ion conductive polymer, H may be substituted with Na, K, Li, Cs or tetrabutylammonium. In the hydrogen ion conducting group of the hydrogen ion conducting polymer, NaOH or NaCl is substituted when H is replaced with Na, and tetrabutylammonium hydroxide is used when the substituent is substituted with tetrabutylammonium, and K, Li or Cs is also appropriate. Substitutions may be used. Since this substitution method is well known in the art, detailed description thereof will be omitted. In addition, when substituted with Na, K, Li, Cs or tetrabutylammonium, the catalyst layer is then converted back into a proton type (H ⁺ -form) polymer electrolyte membrane by an acid treatment process.

In addition, the polymer electrolyte membrane according to one embodiment of the present invention is more effective to use in a polymer electrolyte fuel cell. This is because even in a direct oxidation fuel cell in which the hydrolysis state of the membrane is constant by using a liquid fuel such as methanol, even if the surface contact angle of the electrolyte membrane is adjusted to show hydrophobicity, the effect may be insignificant, or rather, the effect may be reduced.

On the other hand, in the polymer electrolyte fuel cell, the humidification degree of the oxidant such as the gaseous fuel such as hydrogen gas supplied to the anode electrode and the oxygen gas supplied to the cathode electrode is different from each other, and in particular, its value remains unstable in actual application. In addition, due to the water generated by the fuel cell reaction, the hydration state of the membrane is continuously changed, and the membrane may peel while repeating swelling and shrinking.

In addition, the present inventors thought that the hydrophilicity of the polymer electrolyte membrane could be suppressed. However, the present inventors found that the hydrophobicity of the polymer electrolyte membrane can be effectively suppressed as in the embodiment of the present invention. . That is, since the polymer electrolyte membrane according to the embodiment of the present invention has a surface contact angle capable of exhibiting hydrophobicity, this problem can be suppressed.

In addition, the direct oxidation fuel cell has a relatively low water content polyelectrolyte, while the electrolyte membrane is in a completely humidified state due to the water contained in the liquid fuel. In the fuel cell, hydrogen ion transfer may occur inefficiently because formation of the hydrogen ion channel is weakened, but the electrolyte membrane according to the exemplary embodiment of the present invention may maintain a constant hydration state.

Another embodiment of the present invention is to provide a method for producing a polymer electrolyte membrane. The manufacturing method includes a step of hydrophobic treatment of a hydrocarbon-based hydrogen ion conductive polymer membrane using plasma. The plasma treatment method is a method of modifying a surface by exposing a surface of a polymer electrolyte membrane to a partially ionized gas in a plasma state, and this method occurs on a very small surface, without damaging the polymer electrolyte membrane itself and changing a large physical property therein. It also has the advantage of being able to treat and less pollutants. Hereinafter, the plasma processing will be described in more detail.

The hydrocarbon-based hydrogen ion conductive polymer membrane is placed on the sample holder in the plasma chamber. In this case, one surface facing upward faces the plasma generator, and the other surface facing the plasma generator is directed toward the bottom of the sample holder, so that only one surface is subjected to the plasma treatment. The one surface refers to one surface in the longitudinal direction of the hydrogen ion conductive polymer membrane, that is, one surface in contact with the cathode or anode electrode when the membrane-electrode assembly is manufactured. The hydrogen ion conductive polymer membrane is a membrane formed of the aforementioned hydrogen ion conductive polymer.

As described above, one surface of the hydrogen ion conductive polymer membrane may be plasma treated, and after treating one surface, the surface opposite thereto may be subjected to the same plasma treatment, and both surfaces may be plasma treated.

Subsequently, plasma treatment is performed while blowing a first gas selected from argon gas, nitrogen gas, oxygen gas, helium gas, or a combination thereof, and a second gas selected from hydrocarbon gas, fluorocarbon gas, or a combination thereof. . In one embodiment of the present invention, the plasma treatment may be performed while blowing a second gas of fluorocarbon gas together with the first gas.

The hydrocarbon gas may be a gas selected from CH ₄ gas, a C ₂ H ₂ gas or a combination thereof, and the fluorocarbon gas is a gas selected from a CF ₄ gas, a C ₄ F ₈ gas, or a combination thereof. Can be used. When the gas is mixed and used, the mixing ratio can be properly adjusted. In addition, the C ₂ H ₂ gas may be commercially available in the form of C ₂ H ₂ / Ar gas, C ₂ H ₂ / He gas, C ₂ H ₂ / N ₂ gas. At this time, the mixing ratio of the C ₂ H ₂ gas and Ar, He, N ₂ gas does not have a substantial effect on the effect of the present invention, it can be used by appropriately adjusted.

In the plasma treatment, the blowing rate may be 15 L / min to 30 L / min, and 20 L / min to 25 L / min. When the blowing speed of the first gas is included in the above range, the plasma may be formed well, and the radical reaction of the second gas may be smoothly performed.

In the plasma treatment, a blowing rate of blowing the second gas may be 5 ml / min to 50 ml / min. At this time, when the rate of blowing the second gas is adjusted to 5ml / min to 20ml / min, more specifically, 10ml / min to 15mlL / min, weak hydrophobicity can be exhibited, and the rate of blowing the second gas is 20ml. When adjusted to / min to 50ml / min, it is possible to exhibit super water. If the blowing speed of the second gas is included in the above range, there may be an advantage that the radical reaction does not interfere with the plasma of the first gas and the radical reaction occurs properly on the polymer surface without wasting gas.

In one embodiment of the present invention, the surface contact angle of the obtained polymer electrolyte membrane can be adjusted according to the type of gas atmosphere to be subjected to the plasma treatment.

For example, the plasma treatment process may include a first gas selected from argon gas, nitrogen gas, oxygen gas, helium gas, or a combination thereof, and an agent selected from CF ₄ gas, C ₄ F ₈ gas, and combinations thereof. When carried out under the conditions of blowing 2 gases, the surface contact angle of the polymer electrolyte membrane can exhibit weak hydrophobicity of 80 degrees (°) or more and less than 120 degrees (°).

The plasma treatment process may also be performed from a first gas selected from argon gas, nitrogen gas, oxygen gas, helium gas, or a combination thereof, and a C ₂ H ₂ gas, CF ₄ gas, C ₄ F ₈ gas, or a combination thereof. When carried out under the conditions of blowing the selected second gas, the surface contact angle of the polymer electrolyte membrane may exhibit super hydrophobicity of 120 ° to 180 °.

Accordingly, in the present invention, the plasma treatment process may include the first gas selected from argon gas, nitrogen gas, oxygen gas, helium gas, or a combination thereof, and CF ₄ gas, C ₄ F ₈ gas, and a combination thereof. It is more appropriate to carry out under conditions for blowing a second gas selected from the combination.

In this way, the surface properties of the polymer electrolyte membrane can be easily adjusted according to the purpose by plasma treatment.

According to this process, only the physical properties of the surface of the polymer electrolyte membrane are hydrophobic in the range of 80 (degrees) to 180 degrees (degrees), for example, at least 80 degrees (degrees), weak hydrophobicity of the contact angle less than 120 degrees (degrees), 120 degrees (degrees) To 180 degrees (°) can be adjusted to show the super hydrophobicity, the physical properties of the polymer electrolyte membrane to maintain the properties of the hydrogen ion conductive polymer membrane itself. Therefore, when the polymer electrolyte membrane internal physical properties also exhibit hydrophobicity included in the above range, that is, when the polymer electrolyte membrane is prepared by including a material having hydrophobicity, the moisture content is too low, there may be a disadvantage that the hydrogen ion conductivity is very low. However, the polymer electrolyte membrane according to one aspect of the present invention does not have this problem.

Another embodiment of the present invention relates to a polymer electrolyte fuel cell system.

The fuel cell system includes an electricity generator, a fuel supply, and an oxidant supply. The electricity generation unit serves to generate electricity through the oxidation reaction of the fuel and the reduction reaction of the oxidant. The fuel supply unit serves to supply fuel to the electricity generation unit, and the oxidant supply unit serves to supply an oxidant to the electricity generation unit. Examples of the oxidant include oxygen or air. In addition, the fuel may include a hydrogen fuel in the gas or liquid state.

The electricity generating unit includes an anode electrode and a cathode electrode positioned to face each other, and includes at least one membrane-electrode assembly and a separator including a polymer electrolyte membrane positioned between the anode electrode and the cathode electrode. The polymer electrolyte membrane may be bonded to a binder included in an anode electrode and a cathode electrode. The polymer electrolyte membrane is a polymer electrolyte membrane according to one embodiment of the present invention, which will be described in more detail.

The polymer electrolyte membrane has a first surface in contact with the anode electrode and a second surface in contact with the cathode electrode, and a contact angle of at least one of the first surface and the second surface is 80 degrees (°) to 180 degrees ( °). In addition, the contact angle of at least one of the first surface and the second surface may be 80 degrees (°) or more and less than 120 degrees (°).

In one embodiment of the present invention, the contact angle of the second surface may be 80 degrees (°) to 180 degrees (°), 80 degrees (°) or more, may be less than 120 degrees (°). When the contact angle of the second surface is in the above range, since the concentration of water at the cathode is higher than that of the anode, the swelling problem of the electrolyte membrane, the problem of lowering the concentration of hydrogen ions, and the problem of water flooding in the electrode layer. Can be suppressed more effectively.

In addition, both the first and second surfaces may be 80 degrees (°) to 180 degrees (°), and may be 80 degrees (°) or more and less than 120 degrees (°). When the contact angles of the first and second surfaces are both within the above ranges, the electrode and electrolyte can be more effectively suppressed while the problem of swelling of the electrolyte membrane, the problem of lowering the concentration of hydrogen ions, and the problem of water flooding in the electrode layer can be more effectively suppressed. The contactability of the membrane can be improved, the overall interfacial resistance can be greatly lowered, and the loss of moisture in the electrolyte membrane to the outside can be effectively suppressed, so that a polymer electrolyte fuel cell exhibiting better cell chemistry can be provided.

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

In the catalyst layer, any catalyst that can be used as a catalyst may be used as a catalyst in the reaction of a fuel cell, and a representative platinum-based catalyst may be used as a representative example. The platinum-based catalyst may be platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy or platinum-M alloy (M is Ga, Ti, V, Cr, Mn, Fe, Co, Ni, At least one catalyst selected from the group consisting of Cu, Zn, Sn, Mo, W, Rh and Ru).

In addition, such a metal catalyst may be used as the metal catalyst (black) itself, or may be supported on a carrier. As the carrier, carbonaceous materials such as graphite, denka black, ketjen black, acetylene black, carbon nanotube, carbon nanofiber, carbon nanowire, carbon nanoball or activated carbon may be used, or alumina, silica, zirconia, Inorganic fine particles such as titania may be used, but carbon-based materials are generally used. In the case of using the noble metal supported on the carrier as a catalyst, a commercially available commercially available product may be used, or the noble metal supported on the carrier may be prepared and used. Since the process of supporting the precious metal on the carrier is well known in the art, detailed descriptions thereof will be readily understood by those skilled in the art even if the detailed description is omitted.

The catalyst layer also improves the adhesion between the polymer electrolyte membrane and the electrode and includes a binder for the transfer of hydrogen ions.

The binder may be a polymer resin having hydrogen ion conductivity, and examples thereof include a polymer resin having a cation exchange group selected from the group consisting of sulfonic acid groups, carboxylic acid groups, phosphoric acid groups, phosphonic acid groups, and derivatives thereof in a side chain thereof. Can be mentioned. Specific examples of the binder include fluorine polymers, benzimidazole polymers, benz oxide polymers, polyimide polymers, polyetherimide polymers, polyphenylene sulfide polymers, polysulfone polymers, polyether sulfone polymers, and polyethers. It may include one or more hydrogen ion conductive polymer selected from ketone-based polymer, polyether-etherketone-based polymer or polyphenylquinoxaline-based polymer.

Specific examples of the hydrogen ion conductive polymer include a mixture of poly (perfluorosulfonic acid) (including commercialized Nafion, etc.), poly (perfluorocarboxylic acid), and tetrafluoroethylene and fluorovinyl ether containing sulfonic acid groups. Coalescing, sulfonated poly arylene ere sulfone, sulfonated poly ether ether ketone, sulfonated poly phosphazene, sulfonated poly arylene sulfide, sulfonated poly arylene sulfide sulfide, poly benzoxazole, poly (2,2 ' -m-phenylene) -5,5'-bibenzimidazole [poly (2,2'-m-phenylene) -5,5'-bibenzimidazole] or poly (2,5-benzimidazole) selected from One containing at least one hydrogen ion conductive polymer can be used.

The hydrogen ion conductive polymer may replace H with Na, K, Li, Cs or tetrabutylammonium in a cation exchanger at the side chain terminal. In case of substituting H with Na in the ion-exchange group of the side chain terminal, NaOH or Nacl is substituted with tetrabutylammonium when preparing the catalyst composition, and tetrabutylammonium hydroxide is used. K, Li or Cs is also appropriate. Substitutions may be used. Since this substitution method is well known in the art, detailed description thereof will be omitted.

The binder may be used in the form of a single substance or a mixture, and may also be optionally used with a nonconductive compound for the purpose of further improving adhesion to the polymer electrolyte membrane. It is preferable to adjust the usage-amount so that it may be suitable for a purpose of use.

Examples of the non-conductive compound include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro alkylvinyl ether copolymer (PFA), ethylene / tetrafluoro Ethylene / tetrafluoroethylene (ETFE), ethylenechlorotrifluoro-ethylene copolymer (ECTFE), polyvinylidene fluoride, copolymer of polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), dode At least one selected from the group consisting of silbenzenesulfonic acid and sorbitol is more preferred.

The electrode substrate plays a role of supporting the electrode and diffuses the fuel and the oxidant to the catalyst layer, thereby serving to easily access the fuel and the oxidant to the catalyst layer. The electrode substrate is a conductive substrate, and representative examples thereof include carbon paper, carbon cloth, carbon felt, or metal cloth (porous film or polymer fiber composed of metal in a fibrous state). The metal film is formed on the surface of the formed cloth) may be used, but is not limited thereto.

In addition, it is preferable to use a water-repellent treatment with a fluorine-based resin as the electrode base material because it can prevent the reactant diffusion efficiency from being lowered by water generated when the fuel cell is driven. Examples of the fluorine-based resins include polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl fluoride alkoxy vinyl ether, and fluorinated ethylene propylene ( Fluorinated ethylene propylene), polychlorotrifluoroethylene or copolymers thereof can be used.

In addition, a microporous layer may be further included to enhance the reactant diffusion effect in the electrode substrate. These microporous layers are generally conductive powders having a small particle diameter, such as carbon powder, carbon black, acetylene black, activated carbon, carbon fiber, fullerene, carbon nanotubes, carbon nanowires, and carbon nanohorns. -horn or carbon nano ring.

The microporous layer is prepared by coating a composition comprising a conductive powder, a binder resin and a solvent on the electrode substrate. The binder resin may be polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl fluoride, alkoxy vinyl ether, polyvinyl alcohol, cellulose acetate Or copolymers thereof and the like can be preferably used. As the solvent, alcohols such as ethanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol, water, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran, etc. may be preferably used. The coating process may be screen printing, spray coating, or coating using a doctor blade according to the viscosity of the composition, but is not limited thereto.

A schematic structure of the fuel cell system of the present invention is shown in FIG. 2, which will be described in more detail with reference to the following. Although the structure shown in FIG. 2 shows a system for supplying fuel and oxidant to an electric generator using a pump, the fuel cell system of the present invention is not limited to such a structure, and a fuel cell using a diffusion method without using a pump is shown. Of course, it can also be used for system architecture.

The fuel cell system 1 of the present invention includes at least one electricity generation unit 3 for generating electrical energy through an oxidation reaction of a fuel and a reduction reaction of an oxidant, a fuel supply unit 5 for supplying the fuel, And an oxidant supply unit 7 for supplying an oxidant to the electricity generation unit 3.

In addition, the fuel supply unit 5 for supplying the fuel may include a fuel tank 9 storing fuel and a fuel pump 11 connected to the fuel tank 9. The fuel pump 11 serves to discharge the fuel stored in the fuel tank 9 by a predetermined pumping force.

The oxidant supply unit 7 for supplying the oxidant to the electricity generating unit 3 includes at least one oxidant pump 13 for sucking the oxidant with a predetermined pumping force.

The electricity generator 3 is composed of a membrane-electrode assembly 17 for oxidizing and reducing a fuel and an oxidant, and a separator 19 and 19 'for supplying fuel and an oxidant to both sides of the membrane-electrode assembly. At least one of these electricity generating units 3 constitutes a stack 15.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention and the present invention is not limited to the following examples.

(Example 1)

A sample holder is formed of a polymer resin comprising a polymer resin including a first repeating unit represented by the following Chemical Formula 1a and a second repeating unit represented by the following Chemical Formula 1b in a 4: 6 molar ratio, and having a thickness of 35 μm in a plasma chamber. On one side facing the plasma generator and the other side facing the bottom of the sample holder.

[Formula 1a]

 [Formula 1b]

Subsequently, plasma treatment was performed while blowing helium gas at a rate of 25 L / min and a C ₄ F ₈ gas at a rate of 15 ml / min to prepare an electrolyte membrane treated with one surface of a hydrophobic surface.

Subsequently, plasma was treated again on the one side of the hydrophobic surface-treated electrolyte membrane under the same conditions as the non-hydrophobic surface (the surface opposite to the hydrophobic surface), thereby preparing a polymer electrolyte membrane for a fuel cell in which both surfaces were hydrophobic.

In the prepared polymer electrolyte membrane, hydrophobic surface treatment was performed up to 50 nm in the depth direction at the outermost surface.

(Example 2)

A hydrogen ion conductive polymer membrane formed of the polymer resin used in Example 1 and having a thickness of 35 μm is placed on the sample holder in the plasma chamber, so that one surface thereof facing upward is directed toward the plasma generator, and the other surface opposite thereto is the sample holder. Face down.

Subsequently, plasma treatment was performed while blowing helium gas at a rate of ₂₅ L / min and also C ₂ H ₂ gas, C ₄ F ₈ gas and C ₄ F ₈ gas at 50 ml / min, 10 ml / min and 15 ml / min, respectively. One surface of the polymer electrolyte membrane with a superhydrophobic surface treatment was prepared.

Subsequently, the surface of the superhydrophobic non-hydrophobic surface (surface opposite to the superhydrophobic surface) of the superhydrophobic surface-treated electrolyte membrane was treated with plasma again, and both surfaces were superhydrophobic. Membrane was prepared

Superhydrophobic surface treatment in the prepared polymer electrolyte membrane was up to 110nm in the depth direction from the outermost surface.

(Comparative Example 1)

A hydrogen ion conductive polymer membrane (thickness 35 μm) made of the polymer resin used in Example 1 was used as the polymer electrolyte membrane for fuel cells.

(Comparative Example 2)

Except that the hydrogen ion conductive polymer membrane (thickness 35㎛) made of the polymer resin used in Example 1 was plasma treated while blowing nitrogen gas and oxygen gas at a rate of 10 ml / min in the air, respectively. In the same manner as in 1, a polymer electrolyte membrane for a fuel cell in which only one surface was hydrophilic was treated. In the prepared polymer electrolyte membrane, hydrophilic surface treatment was performed up to 0.2 nm in the depth direction at the outermost surface.

* Surface contact angle measurement

The surface contact angles of the polymer electrolyte membranes of Examples 1 to 2 and Comparative Examples 1 and 2 with respect to distilled water were measured to be 109.3 degrees (°) (weak hydrophobic), 137.2 degrees (°) (superhydrophobic), and 86.3 degrees (°). (Hydrophilicity: Hydrophobic polymer electrolyte membrane, 78.4 degrees (°) (hydrophilicity) was shown, the surface angle measurement was generally measured using a commercially available equipment (DIGIDROP, GBX), the method is injection After the droplets were dropped on the surface of the polymer electrolyte membrane using a needle like a needle, the shape of the droplets formed on the membrane surface was observed, and the angle between the membrane surface and the inside of the droplets was measured.

* Battery performance measurement

Using the polymer electrolyte membranes of Examples 1 to 2 and Comparative Example 1 to prepare a membrane-electrode assembly in a conventional manner, using the unit cell was prepared.

In this case, as the cathode electrode and the anode electrode, 0.3 g of Pt / C (Pt supported on carbon, 20% by weight of Pt, 80% by weight of carbon) catalyst and Nafion binder (5% by weight of Nafion / H ₂ O / isopropanol) A catalyst composition containing 0.495 g was prepared by screen printing on 35BC of SGL, a carbon paper electrode substrate having a fine pore layer. The final platinum loading of the anode electrode and cathode electrode was 0.3 mg / cm 2, respectively.

1) Current density and power density measurement

The current density and the output density of the unit cell were measured under 0.6V and 0.5V at 65 ° C of 100% relative humidity, and the results are shown in Table 1 below. At this time, H ₂ was used as a fuel at 100 ccm (Cubic Centimeter per Minute) and O ₂ was used as an oxidizing agent at 100 ccm.

Table 1

	0.6 V		0.5 V
	Current density (mA / cm 2 )	Power density (W / cm 2 )	Current density (mA / cm 2 )	Power density (W / cm 2 )
Example 1	900	0.54	1300	0.65
Example 2	600	0.36	850	0.425
Comparative Example 1	350	0.24	800	0.4

As shown in Table 1, the fuel cell using the polymer electrolyte membranes of Examples 1 to 2 having surface contact angles of 109.3 degrees (°) and 137.2 degrees (°) has a current density and an output density of 86.3 degrees ( It can be seen that it is very excellent with respect to Comparative Example 1 which is °). That is, it can be seen that the current density and the output density are improved when the surface contact angle of the polymer electrolyte membrane is 90 degrees (°) to 180 degrees (°).

2) moisture content measurement

The moisture content of the polymer electrolyte membranes of Examples 1 and 2 and Comparative Examples 1 and 2 were measured at 30 ° C., and the results are shown in FIG. 3. The moisture content was measured by sufficiently drying the polymer electrolyte membrane in a 110 ° C. vacuum oven, and then measuring the weight of the polymer electrolyte membrane. Subsequently, the polymer electrolyte membrane was immersed in ultrapure water at 30 ° C. for one day, sufficiently hydrated, and the weight of the hydrated membrane was measured, and then calculated according to the following Equation 1.

[Equation 1]

Water content = (hydrated membrane weight-dried membrane weight) / dried membrane weight x 100

As shown in FIG. 3, the moisture content of the polymer electrolyte membranes of Examples 1 to 2 was slightly reduced compared to that of the polymer electrolyte membrane of Comparative Example 1, but the difference was not so large. Therefore, even if the surface of the polymer electrolyte membrane shows hydrophobicity, it can be seen that there is no change in moisture content. In the case of Comparative Example 2, since the hydrophilicity was further enhanced, it can be seen that the water content increased from Comparative Example 1.

3) Dimensional stability

Dimensional stability of the polymer electrolyte membranes of Examples 1 and 2 and Comparative Examples 1 and 2 were measured, and the results are shown in FIG. 4. Dimensional stability is determined by measuring the dimensional (area) change rate before and after hydration, and the smaller the dimensional (area) change rate is, the higher the dimensional stability is. The rate of dimensional change was measured as follows.

After the polymer electrolyte membrane was sufficiently dried in a vacuum oven at 110 ° C., the area of the polymer electrolyte membrane was measured. Subsequently, it was soaked in ultrapure water at 30 ° C. for one day, sufficiently hydrated, and then the area of the hydrated film was measured, and then calculated according to the following equation.

[Equation 2]

Rate of dimensional change = (hydrated membrane area-dried membrane area) / dried membrane area x 100

As shown in Figure 4, it can be seen that the dimensional stability of Examples 1 to 2 are superior to Comparative Examples 1 to 2.

4) Measurement of battery performance of unit cell

The battery performance of the unit cells manufactured using the polymer electrolyte membranes of Examples 1 to 2 and Comparative Example 1 was measured, and the results are shown in FIG. 5. As shown in FIG. 5, the polymer electrolyte membranes (Examples 1 and 2) showing weak hydrophobicity and superhydrophobicity showed high unit cell performance when compared with Comparative Example 1 showing hydrophilicity. Can be. Since the surfaces of the polymer electrolyte membranes of Examples 1 to 2 exhibit hydrophobicity, they exhibit high adhesion to the Nafion binder of the catalyst layer showing hydrophobicity, thereby lowering the resistance of the electrode-fluorine-based polymer binder-polymer electrolyte membrane. It is because the moisture content which determines hydrogen ion conductivity as shown in 3-4 can have high dimensional stability, without making it fall significantly.

(Example 3)

A sample holder is formed of a polymer resin comprising a polymer resin including a first repeating unit represented by the following Chemical Formula 1a and a second repeating unit represented by the following Chemical Formula 1b in a 4: 6 molar ratio, and having a thickness of 35 μm in a plasma chamber. On one side facing the plasma generator and the other side facing the bottom of the sample holder.

[Formula 1a]

[Formula 1b]

Subsequently, helium and C ₄ F ₈ gas were blown at a rate of 25 L / min and 10 ml / min, respectively, to prepare a polymer electrolyte membrane for a polymer electrolyte membrane fuel cell, in which only one surface was hydrophobic. In the prepared polymer electrolyte membrane, hydrophobic surface treatment was performed up to 0.2 nm in the depth direction at the outermost surface.

(Example 4)

One surface prepared in Example 3 was carried out in the same manner as in Example 3 with respect to the untreated surface (the surface opposite to the hydrophobic surface treated surface) of the hydrophobic surface treated polymer electrolyte membrane, and both surfaces were hydrophobic surfaces. A polymer electrolyte membrane for a treated polymer electrolyte membrane fuel cell was prepared. In the prepared polymer electrolyte membrane, hydrophobic surface treatment was performed up to 0.2 nm in depth direction at the outermost surface.

(Example 5)

Except that helium, C ₄ F ₈ gas and C ₂ H ₂ / Ar gas was plasma treated while blowing at a rate of 25L / min, 10ml / min and 50ml / min, respectively, the same manner as in Example 3 A polymer electrolyte membrane for a polymer electrolyte membrane-type fuel cell treated with a superhydrophobic surface was prepared. Superhydrophobic surface treatment in the prepared polymer electrolyte membrane was up to 110nm in the depth direction from the outermost surface.

(Example 6)

A catalyst composition comprising 0.3 g of Pt / C (Pt supported on carbon, 20 wt% Pt, 80 wt% carbon) catalyst and 0.495 g of Nafion binder (5 wt% Nafion / H ₂ O / isopropanol) The cathode was formed by screen printing on 35BC of SGL, a carbon paper electrode substrate having a fine pore layer, on which a cathode catalyst layer was formed.

A catalyst composition comprising 0.3 g of Pt / C (Pt supported on carbon, 20 wt% Pt, 80 wt% carbon) catalyst and 0.495 g of Nafion binder (5 wt% Nafion / H ₂ O / isopropanol) An anode electrode on which an anode catalyst layer was formed was formed by screen printing on 35BC of SGL, a carbon paper electrode substrate having a fine pore layer.

The final platinum loading of the anode electrode and cathode electrode was 0.3 mg / cm 2, respectively.

After placing the polymer electrolyte membrane prepared in Example 3 between the cathode electrode and the anode electrode, a membrane-electrode assembly was manufactured by a conventional method, and a unit cell was manufactured using the same. At this time, the hydrophobic surface-treated surface of the polymer electrolyte membrane was positioned in contact with the anode catalyst layer of the anode electrode.

(Example 7)

A unit cell was prepared in the same manner as in Example 6 except that the hydrophobic surface-treated surface of the polymer electrolyte membrane was placed in contact with the cathode catalyst layer of the cathode electrode.

(Example 8)

A unit cell was prepared in the same manner as in Example 6 except that both surfaces of the polymer electrolyte membrane prepared in Example 4 were hydrophobic surface-treated electrolyte membrane.

(Comparative Example 3)

A membrane made of a polymer resin represented by Chemical Formula 1 was used as a polymer electrolyte membrane for a fuel cell. A unit cell was prepared in the same manner as in Example 6 except that the polymer electrolyte membrane was used.

(Comparative Example 4)

Example 3 except that the membrane (thickness 35㎛) made of a polymer resin represented by the formula (1) was plasma treated while blowing nitrogen gas and oxygen gas at a rate of 10 ml / min and 15 ml / min in the air In the same manner, a polymer electrolyte membrane for a fuel cell in which only one surface was hydrophilic was treated. In the prepared polymer electrolyte membrane, hydrophilic surface treatment was performed up to 0.2 nm in the depth direction at the outermost surface.

(Comparative Example 5)

One surface prepared in Comparative Example 4 was subjected to the surface treatment of the hydrophilic surface-treated polymer electrolyte membrane (the surface opposite to the hydrophilic surface-treated surface) in the same manner as in Comparative Example 4, where the face was hydrophilic surface treatment. To prepare a polymer electrolyte membrane for a fuel cell. In the prepared polymer electrolyte membrane, hydrophobic surface treatment was performed up to 0.2 nm in depth direction at the outermost surface.

(Comparative Example 6)

A unit cell was prepared in the same manner as in Example 6, except that the polymer electrolyte membrane prepared according to Comparative Example 4 was used.

(Comparative Example 7)

A unit cell was prepared in the same manner as in Example 7, except that the polymer electrolyte membrane prepared according to Comparative Example 4 was used.

(Comparative Example 8)

A unit cell was prepared in the same manner as in Example 8, except that the polymer electrolyte membrane prepared according to Comparative Example 5 was used.

(Comparative Example 9)

Using a commercially available Nafion polyelectrolyte membrane (Dupont), using the anode electrode and the cathode electrode prepared in Example 3, to prepare a membrane-electrode assembly in a conventional manner, to prepare a unit cell using the same It was.

* Surface contact angle measurement

As a result of measuring the surface contact angle of distilled water of the polymer electrolyte membrane prepared according to Examples 3 and 5 and Comparative Example 3, Example 3 was 85.3 degrees (°), Example 5 was 130 degrees (°), Comparative Example 3 was 51.9 degrees (°). That is, it can be seen that Example 3 is hydrophobic, Example 5 is superhydrophobic, and Comparative Example 3 is hydrophilic.

* Battery performance measurement

The current density and output density of the unit cells of Examples 6 to 8, Comparative Example 3, and Comparative Example 9 were operated at 0.6 V and 0.5 V, respectively, at the relative humidity and battery temperature conditions shown in Table 2 below. Was measured. Among the results, the results of Examples 6 to 8 and Comparative Example 3 are shown in Table 3 below. In Table 3, RHXX means that the relative humidity is XX%.

TABLE 2

Relative Humidity (%)	Battery temperature (℃)	Fuel (H 2 ) Anode Supply (ccm)	Oxidizer (O 2 ) cathode supply amount (ccm)
100	70	100	100
65	70	100	100
45	70	100	100

TABLE 3

	RH (%)	0.6 V		0.5 V
		Current density (mA / cm 2 )	Power density (W / cm 2 )	Current density (mA / cm 2 )	Power density (W / cm 2 )
Comparative Example 3	RH100	0.68	0.41	1.14	0.57
	RH65	0.53	0.32	1.01	0.51
	RH45	0.25	0.15	0.57	0.29
Example 6	RH100	0.71	0.43	1.21	0.61
	RH65	0.42	0.25	0.94	0.47
	RH45	0.21	0.13	0.76	0.38
Example 7	RH100	0.81	0.48	1.19	0.6
	RH65	0.44	0.26	0.89	0.45
	RH45	0.41	0.24	0.79	0.39
Example 8	RH100	1.14	0.68	1.86	0.93
	RH65	0.93	0.56	1.68	0.84
	RH45	0.8	0.48	1.53	0.77

In addition, the experimental results of Examples 6 to 8 and Comparative Examples 3 and 9 when the relative humidity is 100% are shown in FIG. 6. In addition, the experimental results of Examples 6 to 8 and Comparative Example 3 when the relative humidity is 65% is shown in Figure 7, the experimental results when the relative humidity is 45% is shown in FIG.

As shown in Table 3 and FIG. 6, when the relative humidity is 100%, the output densities and current densities of the batteries of Examples 6 and 7 are somewhat better than those of Comparative Example 3, and the output of the batteries of Example 8 It can be seen that the density and the current density are remarkably superior to Comparative Example 3. Particularly, in the case of Example 8, the output density and the current density were similar or higher than those using the Nafion polymer electrolyte membrane of Comparative Example 9, and thus, when the polymer electrolyte membrane having the hydrophobic treatment formed on both sides was used, the hydrocarbon-based polymer electrolyte was used. It can be seen that the use of a membrane has similar or higher electrochemical performance than Nafion.

In addition, as shown in Table 3 and FIGS. 7 and 8, the output densities and current densities of the batteries of Examples 6 and 7 were similar or somewhat lower than those of Comparative Example 3 when the relative humidity was 65%. When the relative humidity is 45%, it is found to be very excellent. In addition, in the case of Example 8, excellent results were obtained for both 65% and 45% relative humidity.

Therefore, from the results of FIGS. 6 to 8 and the results of Table 3, the batteries of Examples 6 to 8 were obtained with excellent output density and current density even under the condition that the relative humidity was low to 45%, It can be seen that it can be operated under low humidity conditions.

* Battery performance measurement

The unit cells were operated at 0.6 V and 0.5 V, respectively, at the relative humidity, humidifier temperature, and battery temperature conditions of the current density and output density of the unit cells of Comparative Examples 6 to 8, Measured. The results are shown in Table 4 below. In addition, the results of Comparative Example 3 are shown in Table 4 together for comparison.

Table 4

	RH (%)	0.6 V		0.5 V
		Current density (mA / cm 2 )	Power density (W / cm 2 )	Current density (mA / cm 2 )	Power density (W / cm 2 )
Comparative Example 3	RH100	0.68	0.41	1.14	0.57
	RH65	0.53	0.32	1.01	0.51
	RH45	0.25	0.15	0.57	0.29
Comparative Example 6	RH100	0.49	0.49	0.81	0.40
	RH65	0.344	0.344	0.67	0.33
	RH45	0	0	0.028	0.013
Comparative Example 7	RH100	0.70	0.70	1.12	0.56
	RH65	0.056	0.056	0.618	0.31
	RH45	0	0	0.05	0.025
Comparative Example 8	RH100	0.152	0.152	0.234	0.12
	RH65	0.162	0.162	0.244	0.12
	RH45	0.104	0.104	0.164	0.082

In addition, when the relative humidity is 100%, the experimental results of Comparative Examples 6 to 9 and Comparative Example 3 are shown in FIG. In addition, when the relative humidity is 65%, the experimental results of Comparative Examples 6 to 8 and Comparative Example 3 are shown in Figure 10, the experimental results when the relative humidity is 45% is shown in FIG. From the results shown in FIG. 9 and Table 5, it can be seen that in Comparative Examples 6 to 8, the output density and the current density were superior to those of Comparative Example 3 regardless of the relative humidity. However, this result was inferior to the output density and current density of the batteries of Examples 6 to 8 shown in Table 3, and to Comparative Example 9 using the Nafion polyelectrolyte membrane.

In addition, as shown in FIG. 10 and Table 5, in Comparative Example 7, when the relative humidity was 100%, similar or somewhat superior results were obtained in Comparative Example 3, but the relative humidity was reduced to 65%. The current density and output density are very low, and the low relative humidity of 45% shows no operation at 0.6V.

In Comparative Example 6, as shown in FIG. 9 and Table 5, the current density and the output density were lower than those of Comparative Example 3 in all the relative humidity conditions, and particularly at 0.6 V when the relative humidity was low at 45%. You can see that it doesn't work at all.

Accordingly, the results of Table 5 and the results of FIGS. 9 to 11 show that the cells of Comparative Examples 6 to 8 are very degraded with respect to Examples 6 to 8, so that the hydrophilic treatment of the polymer electrolyte membrane is rather It can be seen that the battery physical properties can be lowered and it can not be operated under the non-humidity condition or the low-humidity condition.

(Comparative Example 10)

A 51 μm thick Nafion polymer (trade name: NR212, manufactured by DuPont, USA) was placed in the plasma chamber on a sample holder, with one side facing up toward the plasma generator and the other facing the bottom of the sample holder. Oriented.

Subsequently, plasma treatment was performed while blowing helium gas at a rate of 25 L / min and a C ₄ F ₈ gas at a rate of 15 ml / min to prepare an electrolyte membrane treated with one surface of a hydrophobic surface.

(Comparative Example 11)

One surface prepared in Comparative Example 10 was carried out in the same manner as in Comparative Example 10 with respect to the untreated surface (the surface opposite to the hydrophobic surface treated surface) of the hydrophobic surface treated polymer electrolyte membrane, and both surfaces were hydrophobic surfaces. A polymer electrolyte membrane for a treated polymer electrolyte membrane fuel cell was prepared. In the prepared polymer electrolyte membrane, hydrophobic surface treatment was performed up to 0.2 nm in depth direction at the outermost surface.

(Comparative Example 12)

A catalyst composition comprising 0.3 g of Pt / C (Pt supported on carbon, 20 wt% Pt, 80 wt% carbon) catalyst and 0.495 g of Nafion binder (5 wt% Nafion / H ₂ O / isopropanol) The cathode was formed by screen printing on 35BC of SGL, a carbon paper electrode substrate having a fine pore layer, on which a cathode catalyst layer was formed.

A catalyst composition comprising 0.3 g of Pt / C (Pt supported on carbon, 20 wt% Pt, 80 wt% carbon) catalyst and 0.495 g of Nafion binder (5 wt% Nafion / H ₂ O / isopropanol) An anode electrode on which an anode catalyst layer was formed was formed by screen printing on 35BC of SGL, a carbon paper electrode substrate having a fine pore layer.

The final platinum loading of the anode electrode and cathode electrode was 0.3 mg / cm 2, respectively.

After placing the polymer electrolyte membrane prepared in Comparative Example 10 between the cathode electrode and the anode electrode, a membrane-electrode assembly was manufactured by a conventional method, and a unit cell was prepared using the same. At this time, the hydrophobic surface-treated surface of the polymer electrolyte membrane was positioned in contact with the anode catalyst layer of the anode electrode.

(Comparative Example 13)

A unit cell was prepared in the same manner as in Comparative Example 12 except that the hydrophobic surface-treated surface of the polymer electrolyte membrane was placed in contact with the cathode catalyst layer of the cathode electrode.

(Comparative Example 14)

A unit cell was prepared in the same manner as in Comparative Example 12 except that both surfaces of the polymer electrolyte membrane prepared in Comparative Example 11 were hydrophobic surface-treated electrolyte membrane.

(Comparative Example 15)

A unit cell was manufactured in the same manner as in Comparative Example 12, except that a Nafion polymer (trade name: NR212, manufacturer: DuPont (USA)) having a thickness of 51 μm was used as the electrolyte membrane.

* Surface contact angle measurement

As a result of measuring the surface contact angle with respect to the distilled water of the polymer electrolyte membrane prepared according to Comparative Example 10, it was shown that 100.55 degrees (°), it can be seen that the hydrophobicity.

* Battery performance measurement

The current densities and output densities of the unit cells of Comparative Examples 12 to 15 were measured under the conditions of temperature and relative humidity of 100%, 65%, and 45% at 70 ° C., respectively, and the results are shown in FIGS. 12 and 12. (Comparative Example 13), FIG. 14 (Comparative Example 14), and FIG. 15 (Comparative Example 15). In Figures 12-15, RHXX means that the relative humidity is XX%.

As shown in Figs. 12 to 15, irrespective of the relative humidity conditions, the Nafion polymer membranes were hydrophobicly treated, and in Comparative Examples 12 to 14 where the surface was hydrophobic, the comparative example 15 using the untreated Nafion polymer membranes In comparison, it can be seen that the output characteristics are very deteriorated.

In addition, the current density and the output density of the unit cells of Comparative Examples 12 to 15 were measured under the conditions of temperature and relative humidity of 100%, 65% and 45% at 80 ° C., respectively, and the results are shown in FIG. 17 (comparative example 13), FIG. 18 (comparative example 14), and FIG. 19 (comparative example 15). 16 to 19, RHXX means that the relative humidity is XX%.

As shown in Figs. 16 to 19, irrespective of the relative humidity conditions, the Nafion polymer membranes were hydrophobicly treated, and in Comparative Examples 12 to 14 where the surface was hydrophobic, the comparative example 15 using the untreated Nafion polymer membranes In comparison, it can be seen that the output characteristics are very deteriorated.

From this result, it can be seen that when hydrophobic treatment of the fluorine-based polymer electrolyte membrane, rather than the hydrocarbon polymer electrolyte membrane, battery characteristics are deteriorated.

The present invention is not limited to the above embodiments, but may be manufactured in various forms, and a person skilled in the art to which the present invention pertains has another specific form without changing the technical spirit or essential features of the present invention. It will be appreciated that the present invention may be practiced as. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Claims (13)

1. A polymer electrolyte membrane for a polymer electrolyte fuel cell, comprising a hydrocarbon-based hydrogen ion conductive polymer membrane, and having a surface contact angle of 80 degrees (°) to 180 degrees (°).
2. The method of claim 1,

   A polymer electrolyte membrane for a polymer electrolyte fuel cell, wherein the surface contact angle of the polymer electrolyte membrane is 80 degrees (°) or more and less than 120 degrees (°).
3. The method of claim 1,

   The hydrocarbon-based hydrogen ion conductive polymer is a polymer having a hydrogen ion conductive group, the polymer is a benzimidazole-based polymer, benzoxazole-based polymer, polyimide-based polymer, polyetherimide-based polymer, polyphenylene sulfide-based polymer, poly A hydrocarbon polymer selected from the group consisting of sulfone polymers, polyether sulfone polymers, polyether ketone polymers, polyether-ether ketone polymers, polyphenylquinoxaline polymers, copolymers thereof, and combinations thereof Polymer electrolyte membrane for polymer electrolyte fuel cell.
4. Hydrophobic Treatment of Hydrocarbon Hydrogen Conductive Polymer Membrane

   Method for producing a polymer electrolyte membrane for a surface-treated polymer electrolyte fuel cell comprising a step.
5. The method of claim 4, wherein

   The hydrophobic treatment using the plasma may include a first gas selected from argon gas, nitrogen gas, oxygen gas, helium gas, and a combination thereof; And blowing a second gas selected from a hydrocarbon gas, a fluorocarbon gas, and a combination thereof.
6. The method of claim 5,

   The hydrocarbon gas is CH ₄ gas or C ₂ H ₂ gas for producing a polymer electrolyte membrane for a polymer electrolyte fuel cell.
7. The method of claim 5,

   The fluorocarbon gas is a C ₄ F ₈ gas, CF ₄ gas or a combination thereof, a method for producing a polymer electrolyte membrane for a polymer electrolyte fuel cell.
8. The method of claim 4, wherein

   The plasma treatment may include a first gas selected from argon gas, nitrogen gas, oxygen gas, helium gas, and combinations thereof; And CF ₄ gas, C ₄ F ₈ gas, and a second gas selected from the group consisting of a combination thereof.
9. The method of claim 4, wherein

   The hydrocarbon-based hydrogen ion conductive polymer is a polymer having a hydrogen ion conductive group, the polymer is a benzimidazole-based polymer, benzoxazole-based polymer, polyimide-based polymer, polyetherimide-based polymer, polyphenylene sulfide-based polymer, polysul Polymer which is a hydrocarbon-based polymer selected from the group consisting of a phone-based polymer, a polyether sulfone-based polymer, a polyether ketone-based polymer, a polyether-etherketone-based polymer, a polyphenylquinoxaline-based polymer, a copolymer thereof, and a combination thereof Method for producing a polymer electrolyte membrane for an electrolyte fuel cell.
10. At least one membrane-electrode assembly comprising an anode electrode and a cathode electrode positioned opposite to each other, and between the anode electrode and the cathode electrode and comprising a polymer electrolyte membrane comprising a hydrocarbon-based polymer comprising a hydrogen ion conductive group And a separator, the at least one electricity generating unit generating electricity through an oxidation reaction of the fuel and a reduction reaction of the oxidant;

    A fuel supply unit supplying fuel to the electricity generation unit; And

    An oxidant supply unit for supplying an oxidant to the electricity generating unit,

    The polymer electrolyte membrane has a first surface in contact with the anode electrode and a second surface in contact with the cathode electrode, and a contact angle between at least one surface of the first surface and the second surface is 80 degrees (°) to 180 degrees. A polymer electrolyte fuel cell system with degrees (°).
11. The method of claim 10,

    And a contact angle between at least one of the first surface and the second surface is greater than or equal to 80 degrees and less than or equal to 120 degrees.
12. The method of claim 10,

    A polymer electrolyte fuel cell system, wherein the contact angle of the second surface is 80 degrees (°) to 180 degrees (°).
13. The method of claim 10,

    The first surface and the second surface of the polymer electrolyte fuel cell system having a contact angle of 80 degrees (°) to 180 degrees (°).

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