KR101544189B1 - Ink for fuel cell electrode catalyst layer, catalyst layer for fuel cell electrode using the same, preparing methode of the same, membrane electrode assembly and fuel cell including the same - Google Patents

Abstract

The present invention relates to an ink for forming a fuel cell electrode catalyst layer, a method for manufacturing a fuel cell electrode catalyst layer using the same, a membrane electrode assembly, and a fuel cell comprising the same, Can produce a catalyst layer having a structure in which nanoparticles are dense by using a solvent having a chain mobility of hydrogen ion conductive polymer of 2.0 kHz- ¹ to 3.0 kHz ^{- 1} , and a fuel cell electrode catalyst layer manufactured using the same, The membrane electrode assembly, and the fuel cell can exhibit excellent cell efficiency even under the condition that the relative humidity is 0%.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink for forming a fuel cell electrode catalyst layer, a method for manufacturing a fuel cell electrode catalyst layer using the same, a fuel cell electrode catalyst layer, a membrane electrode assembly including the electrode catalyst layer, ELECTRODE USING THE SAME, PREPARING METHODE OF THE SAME, MEMBRANE ELECTRODE ASSEMBLY AND FUEL CELL INCLUDING THE SAME}

The present invention relates to an ink for forming a fuel cell electrode catalyst layer, a method for manufacturing a fuel cell electrode catalyst layer using the same, a fuel cell electrode catalyst layer, a membrane electrode assembly including the same, and a fuel cell.

Recently, as the exhaustion of existing energy resources such as oil and coal is predicted, interest in energy that can replace them is increasing. As a next-generation electrochemical energy conversion device, fuel cells are attracting particular attention due to their advantages such as high efficiency, no emission of pollutants such as NOx and SOx, and abundant fuel.

A fuel cell is a power generation system that converts the chemical reaction energy of a fuel and an oxidant into electric energy. Hydrogen, hydrocarbons such as methanol and butane are used as fuel, and oxygen is used as an oxidant.

The most basic unit for generating electricity in a fuel cell is a membrane electrode assembly (MEA), which is composed of an anode and a cathode formed on both surfaces of an electrolyte membrane and an electrolyte membrane. Referring to the reaction formula of the fuel cell in which hydrogen is used as a fuel in FIGS. 1 and 2 showing the electric generation principle of the fuel cell, oxidation reaction of fuel occurs at the anode electrode, hydrogen ions and electrons are generated, and hydrogen ions are passed through the electrolyte membrane And moves to the cathode electrode. At the cathode electrode, hydrogen ions and electrons transferred through the oxygen (oxidizing agent) and the electrolyte membrane react with each other to generate water. This reaction causes electrons to migrate to the external circuit.

[Reaction Scheme]

The ^{_{anode: H 2 → 2H + + 2e}} -

Cathode electrode: 1 / 2O ₂ + 2H ⁺ + 2e ^- → H ₂ O

Overall reaction: H ₂ + 1 / 2O ₂ → H ₂ O

Membrane electrode assemblies (MEAs) for fuel cells are manufactured in various forms, and are referred to as 3, 5, and 7-layer membrane electrode assemblies depending on the number of constituent layers. The 3-layer membrane electrode assembly is bonded only with the electrolyte membrane, the fuel electrode and the air electrode catalyst, and the 5-layer membrane electrode assembly is formed by adding an electrode support such as carbon paper or carbon cloth to the 3-layer membrane electrode assembly. The portion having such a porous support is referred to as a gas diffusion layer. When a fuel cell stack is manufactured using a membrane electrode assembly, a gasket is required to prevent gas or liquid from leaking at a contact portion with the separator. Such a cask is integrated with the membrane electrode assembly to form a 7- Junction.

2 shows a general configuration of a 5-layer membrane electrode assembly, which includes catalyst layers 203 and 205 and gas diffusion layers 208 located opposite to each other with an electrolyte membrane 201 and an electrolyte membrane 201 sandwiched therebetween . The gas diffusion layer is composed of the electrode supports 209a and 209b and the microporous layers 207a and 207b formed thereon.

The material most commonly used for the electrolyte membrane is a perfluorosulfonic acid-based ion exchange membrane having a sulfonic acid group (-SO ₃ H) and utilizes the inherent proton conduction properties of sulfonated polymers. For example, Nafion membranes, Gore membranes, Flemion membranes, and Aciplex membranes are mainly used.

In the polymer electrolyte fuel cell, due to the characteristics of the sulfonated polymer, the operating temperature is usually 60 to 80 ° C., and it is possible to exert a good performance only when there is humidification from the outside. However, the sulfonated polymer used as the electrolyte membrane of the polymer electrolyte fuel cell is difficult to control the moisture content of the electrolyte membrane during operation. Therefore, an external humidifier is required to supply an appropriate amount of moisture to the electrolyte membrane. There is a disadvantage that it can not respond to simplification. Conventional sulfonated random copolymers exhibit excellent cell performance under 100% humidifying conditions, but have a problem in that their performance deteriorates drastically under low humidification conditions, which are actual operating conditions. This is because the random copolymer does not clearly distinguish the hydrophilic moiety from the hydrophobic moiety and thus can not effectively form a passage through which water can move.

Therefore, the development of a polymer electrolyte fuel cell capable of self-humidification without an external humidifying device has been made at various angles. For example, U.S. Pat. Nos. 5,879,828 and 6,136,412 disclose that when the catalyst is supported on acicular carrier particles, the surface area of the catalyst per unit volume is increased and the electrochemical reaction is increased compared to conventional commercial catalysts, The amount of external humidification can be reduced.

In U.S. Patent No. 6,207,312, a forced convection flow is formed by the supply of gas to a vertical interdigitated gas flow channel and the reaction gas is further propelled to the catalyst layer of both poles to cause an electrochemical reaction, The amount of water is increased and the electrolyte membrane is effectively hydrated, so that self-humidifying operation is possible.

In addition, attempts have been made to improve the performance of a fuel cell in a no-humid condition by containing a catalyst such as platinum for producing water in the catalyst layer and a metal oxide-based hygroscopic material for moisture absorption during the production of the catalyst layer (US 5766787 (1998) . In this case, although it contributed to practically enabling no-humid operation, the effective hydrogen ion transmission was inhibited by the contained material, and the moisture absorption characteristic of the metal oxide other than silica was insufficient at a relative humidity of 50% or less.

Similarly, attempts have been made to improve the performance of dry-humidified operation by containing noble metal catalysts and non-oxide-based harmful substances other than platinum (US 10/657038 (2003), US 0092777A1 (2011)). It has been difficult to realize high fuel cell performance in a membrane electrode assembly.

In order to solve the problems of the prior art as mentioned above, the present invention provides an ink for forming an electrode catalyst layer of a self-humidifying functional fuel cell capable of self-humidification in which a hydrophilic part is clearly separated from a hydrophobic part so that a passage through which water can move is effectively formed. A method for manufacturing a fuel cell electrode catalyst layer, and a fuel cell electrode catalyst layer produced thereby.

The present invention also aims to provide a fuel cell membrane electrode assembly and a fuel cell including the self-humidifying functional catalyst layer according to the present invention.

The present invention has been made to solve the above problems

Hydrogen ion conductive polymer;

A platinum catalyst supported on platinum or carbon; And

Wherein the hydrogen ion conductive polymer has a chain mobility of 2.0 kHz- ¹ to 3.0 kHz ^{- 1} .

The ink for forming a fuel cell electrode catalyst layer according to the present invention includes a solvent in which the hydrogen ion conductive polymer has a chain mobility of 2.0 kHz- ¹ to 3.0 kHz ^{- 1} , whereby the hydrophilic part of the fuel cell electrode, So that a passage through which water can move is effectively formed. In the present invention, the chain mobility of the proton conductive polymer can be measured by NMR, and the unit is kHz ^{- 1} .

For example, Nafion, which is a typical compound as a hydrogen-ion conductive polymer, is a polymer having PTFE as a main chain and a sulfonic acid group as a side chain. Thus, main chains and side chains exhibit different mobility with respect to a specific solvent. Since Nafion contains both F in the main chain and in the side chain, the chain mobility of Nafion in the main chain and side chain can be measured by ¹⁹ F-NMR. The mobility of the Nafion side chain in the solvent can be expressed by the reciprocal of the peak width of F contained in the side chain. The mobility of the Nafion main chain is a relative concept to the mobility of the side chain. The peak area of F contained in the main chain And the peak area of F contained in the side chain.

The ink for forming a fuel cell electrode catalyst layer according to the present invention is characterized in that a plurality of catalysts are aggregated and the hydrogen-ion conductive polymer forms a reverse-micellar structure around the agglomerated catalyst The agglomerate is a catalyst, and the hydrogen ion conductive polymer surrounds the catalyst. In this case, the hydrogen ion conductive polymer has a high level of phase separation and the hydrophilic part is clearly separated from the hydrophobic part, And has a structure in which self-humidification is possible by sequentially forming the passages effectively.

3A is a schematic view of a hydrogen-ion conductive polymer-catalyst integrated body according to the present invention. The ink for forming a fuel cell electrode catalyst layer according to the present invention uses a solvent having a chain mobility of 2.0 kHz- ¹ to 3.0 kHz ^{- 1} of the hydrogen-ion conductive polymer to separate the hydrogen-ion conductive polymer well.

The hydrogen ion conductive polymer includes both a hydrophilic region and a hydrophobic region. Since the hydrophilic region is intimately associated with the platinum catalyst aggregate and has higher permeability to the platinum catalyst aggregate, the phase separation of the hydrogen ion conductive polymer To form a reverse-micelle type proton-conducting polymer-catalyst aggregate.

Referring to FIG. 3b, which is a schematic view of the hydrogen-ion conductive polymer-catalyst aggregate, when a solvent having a low chain-mobility of the hydrogen-ion conductive polymer is used, the hydrophilic region and the hydrophobic region of the hydrogen-ion conductive polymer are irregularly arranged around the catalyst aggregate Thereby reducing the degree of penetration of the hydrophilic region into the catalyst aggregate, resulting in the formation of a hydrogen-ion conductive polymer-catalyst aggregate with no controlled size distribution. In the case of a catalyst layer in which a plurality of hydrogen-ion conducting polymer-catalyst aggregates are gathered, the catalyst layer has a less dense structure due to the nonuniformity of the particle size, thereby forming a catalyst layer having a large gap between the hydrogen-ion conducting polymer-catalyst aggregates.

The diameter of the proton-conducting polymer-catalyst aggregate according to the present invention is 50 to 200 nm

The thickness of the proton conductive polymer contained in the catalyst assembly according to the present invention is 5 to 20 nm.

The ink for forming a fuel cell electrode catalyst layer according to the present invention comprises 1 to 3 parts by weight of a proton conductive polymer, 2 to 5 parts by weight of a catalyst and 40 to 60 parts by weight of a solvent.

The solvent used in the ink for forming the fuel cell electrode catalyst layer according to the present invention has a boiling point of 150 ° C or higher. When the catalyst layer ink prepared by using a solvent having a boiling point of 150 ° C or higher is dried at a relatively low temperature, most of large pores of 400 nm or more are effectively removed.

The solvent used for preparing the ink for forming the fuel cell electrode catalyst layer according to the present invention may be an amide solvent and preferably 1-methyl-2-pyrrolidinone (NMP), N, N-dimethylacetamide , N-dimethylformamide (DMF), Hexamethylphosphoramide (HMPA), and 1,3-Dimethyl-2-imidazolidinone (DMI).

The solvent used for preparing the ink for forming the fuel cell electrode catalyst layer according to the present invention may further include an alcohol-based solvent, and glycerol may be preferably used.

The alcohol-based solvent is a solvent having a low chain-mobility of the hydrogen-ion conductive polymer. The alcohol-based solvent is mixed with an alcohol-based solvent having a low degree of chain mobility of the hydrogen-ion conductive polymer and an amide- The degree of chain mobility of the conductive polymer can be controlled, thereby controlling the degree of density of the catalyst layer.

The perfluorosulfonic acid-based polymer may be used as the proton conductive polymer used in the production of the ink for forming the fuel cell electrode catalyst layer according to the present invention, and preferably Nafion, Flemion, Aciplex ) And Gore (Gore).

The Nafion solution is a mixture of Nafion ionomer and a mixture of an alcohol solvent and water at an appropriate ratio. This improves the contact between the electrode catalyst layer and the electrolyte membrane, thereby improving the utilization of the catalyst. By weight of the electrolyte per ion exchange equivalent weight (equivalent weight; EW) may vary depending on the kind of the electrolyte, of about 1,000 (g / wt) so, a sulfonic acid group per mol up by absorbing water of about 10 mole about 0.1 S㎝ ^-1 High proton conductivity.

The present invention also relates to

A first step of preparing an ink for forming a fuel cell electrode catalyst layer according to the present invention;

A second step of applying the catalyst layer forming ink to a film; And

And drying the ink-coated film at 60 to 100 ° C.

In the method of manufacturing a fuel cell electrode catalyst layer according to the present invention, the step of drying in the third step may be performed such that the residual ratio of the solvent contained in the fuel cell electrode catalyst layer forming ink is not more than 10 wt% Until a predetermined time elapses.

When the residual solvent ratio is more than 10 wt%, the residual solvent is dried to form a relatively large pore. Therefore, it is preferable that the residual solvent ratio is less than 10 wt% in order to maintain the moisture content by the micro pore.

In the third step of the method for manufacturing a fuel cell electrode catalyst layer of the present invention, the drying rate of the solvent is 0.5 wt% / min to 3 wt% / min. The drying rate can be controlled based on the boiling point of the solvent. If the time taken for the residual ratio of the solvent to become 10 wt% is less than 30 minutes, cracks are formed on the surface of the catalyst layer, which leads to deterioration of cell efficiency.

The present invention also provides a fuel cell electrode catalyst layer produced by the method for manufacturing a fuel cell electrode catalyst layer according to the present invention.

The fuel cell electrode catalyst layer according to the present invention is characterized in that the contact angle of the liquid droplet is 110 ^{° C} to 160 ^{° C.}

Since the fuel cell electrode catalyst layer according to the present invention includes a reverse-micelle type proton-conducting polymer-catalyst assembly having a hydrophilic region inside and a hydrophobic region outside, the surface of the catalyst layer is composed of a proton conductive polymer And the contact angle of the droplet of the catalyst layer is increased to 110 ^° or more.

The fuel cell electrode catalyst layer according to the present invention is characterized by showing one peak at 3 nm to 60 nm in the size distribution of micropores.

It is known that the microporosity of 10 nm or less is caused by the micropores of the catalyst material and the micropores inside the hydrogen ion conductive polymer-catalyst aggregate. The catalyst layer for the fuel cell according to the present invention is characterized in that the hydrogen ion conductive polymer The surface and the inside of the catalyst aggregate are well enclosed, thus reducing micropores of less than 10 nm. Further, by drying the catalyst layer forming ink at a low temperature, large pores of 400 nm or more are reduced.

The catalyst layer according to the present invention forms a nano-dense structure having uniform pores of 10 nm to 400 nm. In the catalyst layer according to the present invention, this nano-dense structure allows only a very small amount of water to pass So that even a small amount of water generated at a low current is very well preserved, resulting in high battery efficiency even under no-humid conditions.

The catalyst layer according to the present invention has a thickness of 1 to 90 m.

The present invention also provides a membrane electrode assembly including a fuel cell electrode catalyst layer according to the present invention.

The present invention also relates to

Hydrogen ion conductive polymer membrane;

A first catalyst layer formed on the surface of the proton conductive polymer membrane; And

And a second catalyst layer formed on the surface of the first catalyst layer,

The fuel cell electrode catalyst layer according to the present invention is the first catalyst layer, the second catalyst layer, or the first catalyst layer and the second catalyst layer.

In the case where the fuel cell electrode catalyst layer according to the present invention is the second catalyst layer, since the second catalyst layer passes a very small amount of moisture formed in the first catalyst layer, the water storage efficiency is excellent, .

The membrane electrode assembly according to the present invention may further include a microporous layer, and may further include a gasket. In the membrane electrode assembly according to the present invention, the microporous layer functions to uniformly distribute the fuel or the oxidant to the catalyst layer.

In the membrane electrode assembly according to the present invention, the microporous layer may be a carbon layer coated on the electrode support. In the membrane electrode assembly according to the present invention, the microporous layer may be formed of graphite, carbon nanotubes (CNT), fullerene (C ₆₀ ), activated carbon, vulcan, Ketjen black, carbon black or carbon nano horn And one or more binders selected from the group consisting of poly (perfluorosulfonic acid), poly (tetrafluoroethylene), and florinated ethylene-propylene may be further added. .

The electrode support may be a carbon substrate such as a carbon cloth or carbon paper. The electrode support may be a carbon substrate and may support the electrodes and may disperse fuel, water, air, , And the catalyst layer material.

The present invention also provides a fuel cell including the membrane electrode assembly according to the present invention.

The ink for forming a fuel cell electrode catalyst layer according to the present invention includes a solvent having a high degree of chain mobility of the hydrogen-ion conductive polymer. The fuel cell electrode catalyst layer prepared by controlling the drying rate and the solvent residual ratio with the ink has a pore size and a contact angle This improved nanocomposite structure enables the fuel cell containing the fuel cell to exhibit excellent electric efficiency even under the condition of 0% relative humidity.

1 shows a principle of electricity generation of a fuel cell.
2 shows a general configuration of a membrane electrode assembly for a fuel cell.
3 is a schematic view of a hydrogen-ion conductive polymer-catalyst integrated body according to the present invention.
4 is a graph showing a result of measuring pore distribution of a catalyst layer for a fuel cell according to a ratio of a residual solvent produced in an embodiment of the present invention.
5 is a graph showing a result of SEM measurement of the surface of the catalyst layer for a fuel cell according to the drying rate prepared in one embodiment of the present invention.
6 is a SEM photograph of the catalyst layer for a fuel cell manufactured in one embodiment of the present invention and a comparative example.
FIG. 7 shows AFM photographs of the catalyst layer for a fuel cell manufactured in an embodiment and a comparative example of the present invention.
FIG. 8 shows the results of measurement of the pore distribution of the catalyst layer for a fuel cell manufactured in an embodiment and a comparative example of the present invention.
9 shows the contact angle of the droplet measured while changing the addition ratio of glycerol according to the present invention.
Fig. 10 shows the results of measurement of the amount of water absorption of the catalyst layer for a fuel cell manufactured in one embodiment of the present invention and a comparative example.
FIG. 11 shows the results of measurement of the efficiency of a fuel cell including the catalyst layer for a fuel cell manufactured in one embodiment and a comparative example of the present invention.
12 and 13 show the result of measuring the durability of the fuel cell including the catalyst layer for a fuel cell manufactured in one embodiment and the comparative example of the present invention.
14 shows a visualization test result of a fuel cell including the catalyst layer for a fuel cell manufactured in one embodiment and a comparative example of the present invention.

Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited by the following examples.

< Example  1> Single layer Membrane electrode  Fabrication of the bonded body

A solution of 5 wt% Nafion ^TM solution (DE512, Sigma Aldrich, St. Louis, MO, USA) was added to 1.95 g of 1-methyl-2-pyrrolidinone solvent (99.5 wt% Ion Power, New Castle, DE, USA) and 0.20 g of carbon coated with 20 wt% of platinum were mixed to prepare catalyst layer ink.

The prepared catalyst layer ink was dispersed by ultrasonication for 1 hour and then stirred for 24 hours to prepare a homogeneous solution.

After the cleaned Teflon film was prepared, the prepared catalyst ink was repeatedly coated until the platinum loading amount became 0.2 mg / cm ² , and dried at 80 ° C to prepare a catalyst layer on the Teflon film. To prepare Nafion membranes containing sodium cations, Nafion membranes were mixed with 1 wt% sodium hydroxide solution, heated, transferred to distilled water and heated again.

The catalyst layer formed on the Teflon film was placed on both sides of a Nafion membrane containing sodium cations, followed by hot pressing at 60 ° C for 10 minutes to 20 minutes to remove the Teflon film to prepare a membrane electrode assembly.

< Comparative Example  1>

A membrane electrode assembly of Comparative Example 1 was prepared in the same manner as in Example 1 except that 1.95 g of glycerol was used as a solvent and the drying temperature was 130 캜.

< Experimental Example  1> after drying  Measurement of pore size according to residual solvent ratio

The pore size of the catalyst layer was measured according to the amount of residual solvent after drying for the catalyst layer prepared in Example 1, and the result is shown in FIG. The ratio of the residual solvent amount was determined by measuring the weight before and after drying of the catalyst ink coated on the Teflon film.

As shown in FIG. 4, when the residual solvent ratio is 15 wt% or more, it can be seen that the residual solvent is dried later and relatively large voids are formed.

< Experimental Example  2> Measurement of surface properties by drying rate

The surface of the catalyst layer according to the drying rate was measured by SEM for the catalyst layer prepared in Example 1, and the result is shown in FIG. As shown in FIG. 5, as the time for which the residual solvent ratio reaches 10 wt% is increased to 15 minutes (a), 30 minutes (b), and 45 minutes (c), that is, And the degree of the decrease is decreased.

< Experimental Example  3> SEM  Photo measurement

The surface and cross section of the catalyst layer prepared in Example 1 and Comparative Example 1 were measured by SEM and the results are shown in FIG.

In FIG. 6, the catalyst layer (b) produced by Example 1 has a much smaller void between the particles than the catalyst layer (a) produced by Comparative Example 1. When the same amount of platinum of 0.2 mg / cm ² was loaded, it was found that the thickness of the catalyst layer (d) prepared in Example 1 was about 10.2 μm, which was thinner than the thickness of the catalyst layer (c) prepared in Comparative Example 1 have. It can be seen from the above that the catalyst layer produced by Example 1 according to the present invention forms a denser structure than the catalyst layer produced by Comparative Example 1.

< Experimental Example  4> AFM  Photo measurement

The surface of the catalyst layer prepared in Example 1 and Comparative Example 1 was measured by AFM and the results are shown in FIG.

In FIG. 7, it can be seen that the catalyst layer (a) produced by Comparative Example 1 has micro-sized voids, whereas the catalyst layer (b) produced by Example 1 has a very small void between the particles.

In Fig. 7C and Fig. 7D, the darker portion is the hydrophilic region and the brighter portion is the hydrophobic region, and the catalyst layer (d) produced by Example 1 is superior to the catalyst layer (c) It can be seen that phase separation is better.

7E is a pixel number distribution diagram according to degrees. A higher value based on 0 means a hydrophobic PTFE, and a lower value based on 0 means a hydrophilic sulfonic acid group. It can be seen that the catalyst layer produced by Example 1 exhibits a wider range of degree of distribution than the catalyst layer produced by Comparative Example 1, which indicates that the catalyst layer prepared by Example 1 has greater hydrophilicity and greater hydrophobicity , Indicating that the phase separation of Nafion was better performed in Example 1.

< Experimental Example  5> Pore size measurement

The pore size distribution of the catalyst layer prepared in Example 1 and the pore size distribution of the catalyst layer prepared in Comparative Example 1 were measured and the results are shown in FIG.

8, the catalyst layer prepared in Example 1 exhibits one peak at 10 nm to 300 nm and has a uniform pore distribution. In contrast, the catalyst layer of Comparative Example 1 has a large pore size of 10 nm or less and a pore size of 300 nm or more . &Lt; / RTI &gt;

< Example  2> Double layer Membrane electrode  Fabrication of the bonded body

< Example  2-1>

The catalyst layer 1 was prepared in the same manner as in Comparative Example 1, except that carbon having a platinum loading of 0.16 mg / cm ² was used. A catalyst layer 2 was prepared in the same manner as in Example 1, except that carbon having a platinum loading of 0.04 mg / cm ² was used.

The catalyst layer 1 was placed on both sides of a Nafion membrane containing sodium cations and hot-pressed at 60 ° C for 10 minutes to 20 minutes to remove the Teflon film. After the catalyst layer 2 was placed on the surface of the catalyst layer 1, Minute hot-pressing and removing the Teflon film to prepare a double-layered membrane electrode assembly.

< Example  2-2>

When the amount of platinum supported on carbon of the catalyst layer 1 is 0.18 mg / cm &lt; ² &gt; And the amount of platinum supported on the carbon of the catalyst layer 2 is 0.02 mg / cm &lt; ² &gt; Layered membrane electrode assembly was prepared in the same manner as in Example 2-1,

< Example  2-3>

When the amount of platinum supported on carbon of the catalyst layer 1 is 0.14 mg / cm &lt; ² &gt; , And the platinum loading amount of carbon in the catalyst layer 2 was 0.06 mg / cm ² Layered membrane electrode assembly was prepared in the same manner as in Example 2-1,

< Example  2-4>

A double-layered membrane electrode assembly was prepared in the same manner as in Example 2-1 except that the catalyst layer 2 was prepared using N, N-dimethylacetamide instead of 1-methyl-2-pyrrolidinone.

< Example  2-5>

A double-layered membrane electrode assembly was prepared in the same manner as in Example 2-1 except that the catalyst layer 2 was prepared using N, N-dimethylformamide instead of 1-methyl-2-pyrrolidinone.

< Example  2-6>

Layer membrane electrode assembly was prepared in the same manner as in Example 2-1, except that 4 wt% of glycerol was additionally introduced to prepare catalyst layer 2.

< Example  2-7>

Layer membrane electrode assembly was prepared in the same manner as in Example 2-1 except that 8 wt% of glycerol was additionally introduced to prepare the catalyst layer 2.

< Example  2-8>

Layer membrane electrode assembly was prepared in the same manner as in Example 2-1, except that 12 wt% of glycerol was additionally introduced to prepare the catalyst layer 2.

< Example  2-9>

Layer membrane electrode assembly was prepared in the same manner as in Example 2-1 except that 6 wt% of glycerol was additionally introduced to prepare the catalyst layer 2.

< Experimental Example  6> Contact angle  Measure

1 μl of test liquid was dropped onto the surface of the catalyst layer prepared in Examples 2-1 to 2-8, and the contact angle of the droplets was measured. The results are shown in Table 1 below.

division Average contact angle Example 2-1 157 ^o Example 2-2 158 ^o Example 2-3 155 ^o Examples 2-4 148 ^o Example 2-5 152 ^o Examples 2-6 145 ^o Examples 2-7 132 ^o Examples 2-8 118 ^o Comparative Example 1 105 ^o

In Table 1, the catalyst layers prepared in Examples 2-1 to 2-8 according to the present invention have a contact angle of 110 ^° or more.

< Experimental Example  7> Contact angle  Measure

Of 2.5 kHz to 2.8 kHz ^{-1 -1 -1} of Nafion 0.9 kHz in order to confirm the improved wetting properties of the catalyst layer according to whether the content of 1-methyl-2-pyrrolidinone having a chain mobility to 1.0 kHz or ^-1 The contact angle of the catalyst layer formed while changing the addition ratio of glycerol having the degree of ester chain mobility was measured and the results are shown in FIG.

The total amount of the solvent was kept constant, and the catalyst layer was immersed in distilled water to remove the effect of glycerol residue on the contact angle measurement, and the glycerol was removed by boiling at 100 ° C.

As shown in FIG. 9, the smaller the content of glycerol is, the more the content of 1-methyl-2-pyrrolidone is increased and the contact angle is increased.

< Experimental Example  8> Water absorption measurement

The moisture absorption amount of the membrane electrode assembly according to the relative humidity was measured and the results are shown in FIG. As shown in FIG. 10, the content of glycerol is decreased and the content of 1-methyl-2-pyrrolidone is increased.

< Experimental Example  9> Measurement of fuel cell efficiency by relative humidity

In order to compare and evaluate the performance of the membrane electrode assembly according to the present invention, a unit cell was manufactured and cell performance was shown in Table 2 and FIG.

Table 2 shows the results of measurement of the output density when the relative humidity is 100% and the relative humidity is 0% at 0.5 V, and FIG. 11 (a) is the result of introducing hydrogen into the fuel electrode and introducing oxygen into the air electrode. Is a result of measuring air introduced into the air electrode.

division 100% relative humidity 0% relative humidity Example 2-1 1.6303 A / cm ² 1.5243 A / cm ² Example 2-2 1.6499 A / cm ² 1.5727 A / cm ² Example 2-3 1.6479 A / cm ² 1.4930 A / cm ² Examples 2-4 1.5766 A / cm ² 1.4189 A / cm ² Example 2-5 1.5917 A / cm ² 1.4484 A / cm ² Examples 2-6 1.6612 A / cm ² 1.5452 A / cm ² Examples 2-7 1.6933 A / cm ² 1.5388 A / cm ² Examples 2-8 1.7299 A / cm ² 1.4244 A / cm ² Comparative Example 1 1.6524 A / cm ² 0.1863 A / cm ²

As shown in FIG. 11 and Table 2, the fuel cell including the catalyst layer produced by the present invention exhibits a high output density at 0% relative to Comparative Example 1 at a relative humidity of 0%. From the results of Examples 2-1 to 2-3, the output density at 0% relative humidity was further increased as the thickness of the catalyst layer 2 produced by the present invention increased.

< Experimental Example  10> No humidification  Measuring fuel cell efficiency under conditions

The stability of the fuel cell was evaluated under no-humid conditions and the results are shown in FIG.

The relative humidity of the cathode aeration oxygen was fixed at 0% and the cell voltage was maintained at 0.5 V to remove the effect of changes in oxygen partial pressure.

12, in the fuel cell manufactured in Comparative Example 1, the relative humidity was changed from 100% to 0%, and a water shortage phenomenon occurred in the inside of the fuel cell, resulting in a drastic decrease in performance. On the other hand, It can be seen that only the performance degradation of less than 2% occurs under the condition and then the stable state is maintained again.

< Experimental Example  11> Start-up / shut down  Periodic test measurement

The start-up / shutdown cycle test of the fuel cell was performed under no-humidification conditions, and the results were measured and shown in FIG.

30 seconds in the open-circuit voltage, and performs the start-up / shutdown cycle test to operate at 0.5 V 60 seconds at 100 CCM H _2/350 CCM air conditions for 100 hours.

As shown in FIG. 13, the fuel cell manufactured in Comparative Example 1 restores only 60% of the output density at a relative humidity of 40% in the start-up process, whereas the fuel cell manufactured in Example 1 has a 0% Even at relative humidity, it can be seen that the output density of 93% or more is recovered immediately.

< Experimental Example  12> Liquid- H ₂ O  Visualization test measurement

In order to directly compare the water absorption behavior, a visualization experiment was performed on the cathode flow channel and the results are shown in Fig.

Figure 14a shows an experiment device for liquid -H ₂ O visualization test. Fig. And tested for 3 hours at a high current of 1.5 Acm ^-2 at 40% relative humidity to confirm formation of water droplets.

As shown in FIG. 14B, in the case of the fuel cell including the catalyst layer manufactured according to Comparative Example 1, it is confirmed that the cathode flow channel is clogged by water droplets of micro size or more at various positions. On the other hand, as shown in FIG. 14C, no droplet was observed in the case of the fuel cell including the catalyst layer prepared in Example 1, indicating that the liquid H ₂ O generated in the cathode catalyst layer was well transferred to the anode.

Claims (20)

Hydrogen ion conductive polymer;
A platinum catalyst supported on platinum or carbon; And
Wherein the hydrogen ion conductive polymer has a chain mobility of 2.0 kHz- ¹ to 3.0 kHz- ¹ ,
The fuel cell electrode catalyst layer forming ink
A plurality of catalysts are aggregated,
Wherein the hydrogen-ion conductive polymer has a reverse-micellar structure around the agglomerated catalyst,
Characterized in that a hydrogen-ion conductive polymer-catalyst agglomerate having a diameter of 50 to 200 nm is formed.
The method according to claim 1,
Wherein the ink for forming the fuel cell electrode catalyst layer comprises 1 to 3 parts by weight of the proton conductive polymer, 2 to 5 parts by weight of the catalyst, and 40 to 60 parts by weight of the solvent.
delete delete The method according to claim 1,
Wherein the hydrogen-ion conductive polymer has a thickness of 5 to 20 nm.
The method according to claim 1,
Wherein the solvent has a boiling point of 150 ° C or higher.
The method according to claim 1,
The solvent may be an amide solvent such as 1-methyl-2-pyrrolidinone (NMP), N-dimethylacetamide (DMA), N, N-dimethylformamide (DMF), Hexamethylphosphoramide -imidazolidinone (DMI). &lt; / RTI &gt;
The method according to claim 1,
Wherein the solvent further comprises an alcohol-based solvent.
9. The method of claim 8,
Wherein the alcohol-based solvent is glycerol.
The method according to claim 1,
Wherein the hydrogen-ion conductive polymer is a perfluorosulfonic acid-based polymer.
11. The method of claim 10,
Wherein the perfluorosulfonic acid-based polymer is any one selected from the group consisting of Nafion, Flemion, Aciplex and Gore.
A method for manufacturing a fuel cell electrode catalyst layer, comprising: a first step of preparing an ink for forming a fuel cell electrode catalyst layer according to claim 1;
A second step of applying the catalyst layer forming ink to a film; And
And drying the ink-coated film at 60 to 100 ° C.
13. The method of claim 12,
Wherein the drying in the third step is carried out until the solvent residual ratio becomes 10 wt% or less.
13. The method of claim 12,
The drying in the third step may be performed by a method of manufacturing an electrode catalyst layer for a fuel cell having a solvent drying rate of 0.5 wt% / min to 3 wt% / min
15. A fuel cell electrode catalyst layer produced by the method of any one of claims 12 to 14.
16. The method of claim 15,
The catalyst layer is a liquid droplet contact angle of 110 ^o to 160 ^o a fuel cell electrode catalyst layer.
16. The method of claim 15,
Wherein the catalyst layer exhibits one peak at 3 nm to 60 nm in the size distribution of micropores.
16. The method of claim 15,
Wherein the thickness of the catalyst layer is 2 占 퐉 to 90 占 퐉.
Hydrogen ion conductive polymer membrane;
A first catalyst layer formed on the surface of the proton conductive polymer membrane; And
And a second catalyst layer formed on the surface of the first catalyst layer,
The first catalyst layer, the second catalyst layer, or the first catalyst layer and the second catalyst layer,
15. A membrane electrode assembly according to claim 15, wherein the membrane electrode assembly is a fuel cell electrode catalyst layer.
20. A fuel cell comprising the membrane electrode assembly according to claim 19.

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