KR20190021548A - Electrode catalyst layer of web structure, membrane electrode assembly for electrochemical cell using the same, and manufacturing method - Google Patents

Abstract

The present invention relates to a method for manufacturing a membrane electrode assembly for an electrochemical cell having an electrode catalyst layer of a web structure, which reduces catalytic usage and diffusion resistance of a reactant and a product. The electrode catalyst layer includes a web of an open porous structure in which a fiber is arranged in a three-dimensional structure, and the electrochemical cell is a fuel cell or a water electrolysis cell.

Description

TECHNICAL FIELD The present invention relates to an electrode catalyst layer of a web structure, a membrane electrode assembly for an electrochemical cell using the electrode catalyst layer, and a method of manufacturing the membrane electrode assembly,

The present invention relates to an electrode catalyst layer, and more particularly to an electrode catalyst layer of a web structure that provides an open pore structure in which fibers are arranged in a three-dimensional structure. The present invention also relates to a membrane electrode assembly for an electrochemical cell using the above-described electrode catalyst layer of a web structure and a manufacturing method thereof.

Generally, an electrochemical cell is an energy conversion device that uses electric energy or generates electric energy, and is classified into an electrolysis cell and a fuel cell. For the practical use of electrochemical cells, it is necessary to improve the output density (decrease in electric energy consumption in case of water electrolysis), durability and cost reduction in fuel cells.

1 is a conceptual view of a membrane electrode assembly 100 constituting a part of a typical electrolytic cell producing hydrogen gas and oxygen gas by electrochemically decomposing water, wherein the lower part of FIG. 1 shows the thickness of each component layer .

An electrolytic electrochemical cell for electrolyzing water (H ₂ O) to produce oxygen gas (O ₂ ) and hydrogen gas (H ₂ ) includes a first electrochemical reaction layer 104, a second electrochemical reaction layer 108, a film 106, a first diffusion layer 102, and a second diffusion layer 110. The first electrochemical reaction layer 104 is composed of a first electrochemical catalyst 112 and a first support 114 and the second electrochemical reaction layer 108 is composed of a second electrochemical catalyst 116, And a second carrier (118).

The first diffusion layer 102 and the second diffusion layer 110 assist the transfer of electrons and reactants or products to (or at) the first and second electrochemical catalysts 112 and 116. The first and second electrochemical catalysts 112 and 116 are the most important materials for electrolysis or generating electric energy and the first and second supports 114 and 118 are formed by the first and second electrochemical catalysts 112 and 113, 116 as well as electron transfer paths.

The first and second electrochemical catalysts 112 and 116 are mixed with the first and second carriers 114 and 118, the binder and the solvent to form a slurry or a paste state And the first and second electrochemical reaction layers 104 and 108 are formed on the film 106 or applied to the first and second diffusion layers 102 and 110, respectively. At this time, the "electrochemical reaction layers 104, 108 - the membrane 106" or the "electrochemical reaction layers 104, 108 - the membrane 106 - the diffusion layers 102, 110" Membrane Electrode Assembly (hereinafter referred to as "MEA"). Hereinafter, the MEA centering on the "electrochemical reaction layers 104, 108 - the membrane 106" will be referred to.

The gap between the first electrochemical reaction layer 104 and the second electrochemical reaction layer 108 formed on the MEA has a thickness value of a physical film and the first electrochemical reaction layer 104 and the second electrochemical reaction layer 108 are free of air bubbles, it is possible to operate at low voltage and high current. In addition, since the conductivity of the electrolytic solution is not utilized as in an alkaline electrolytic cell, it is possible to use water as a raw material in high purity, thereby obtaining hydrogen and oxygen of high purity.

A process of electrolyzing water using the configuration shown in FIG. 1 will be described below. Here, the first electrochemical reaction layer 104 is formed where the oxidation reaction occurs, the second electrochemical reaction layer 108 where the reduction reaction occurs, and the oxidation reaction and the reduction reaction occur at the same time.

First, when water (H ₂ O) is supplied to the first electrochemical reaction layer 104 through the first diffusion layer 102, water is supplied to the first electrochemical catalyst 112 (oxidation catalyst, cathode active material, (O ₂ ), electrons (e ^- ) and hydrogen ions (H ⁺ ) (protons) as shown in the following reaction formula 1. At this time, the oxygen gas (O ₂ ) flows out to the outside of the electrolysis cell, and the hydrogen ion (H ⁺ ) passes through the membrane 106 by the electric field and flows through the second electrochemical catalyst 116 (the reducing catalyst, The electrons e ^- flow from the first electrochemical catalyst 112 through the first diffusion layer 102, the external circuit (not shown), and the second diffusion layer 110 to the second electrochemical And moves to the catalyst 116.

On the other hand, in the second electrochemical catalyst 116, hydrogen ions (H ⁺ ) migrated in the first electrochemical catalyst 112 react with electrons (e ^- ) to generate hydrogen gas (H ₂ ) . A part of the water supplied to the first electrochemical reaction layer 104 moves to the second electrochemical reaction layer 108 by an electric field and flows out of the electrolytic cell together with the hydrogen gas (H ₂ ).

The electrochemical reactions occurring in the first electrochemical catalyst 112 and the second electrochemical catalyst 116 are as shown in the following reaction equations 1 and 2, The overall reaction at catalyst 116 is as shown in Scheme 3.

[Reaction Scheme 1]

2H ₂ O? 4H ⁺ + 4e ^- + O ₂ (anode)

[Reaction Scheme 2]

4H ⁺ + 4e ^- ? 2H ₂ (cathode)

[Reaction Scheme 3]

2H ₂ O - > O ₂ + 2H ₂

On the other hand, in the case of a fuel cell, a reaction occurs in reverse to the electrolysis of water.

First, hydrogen gas is introduced into the first electrochemical reaction layer 104, and oxygen gas is supplied to the second electrochemical reaction layer 108. Then, the hydrogen gas is converted into hydrogen ions (protons) and electrons by an electrochemical reaction (see reaction formula 4) in the first electrochemical catalyst 112, and electrons are passed through the membrane through the electrically connected external load, And moves to the electrochemical catalyst 116. Then, in the second electrochemical catalyst 116, protons and electrons produced in the first electrochemical catalyst 112 react with oxygen gas supplied from the outside (see Reaction 5) to generate water, energy and heat, The overall reaction is shown in Scheme 6.

[Reaction Scheme 4]

H ₂ ^- & gt ^; 2H ⁺ + 2e ^- (anode)

[Reaction Scheme 5]

2H ⁺ + 1 / 2O _{2 -} > H ₂ O (cathode)

[Reaction Scheme 6]

H ₂ + 1 / 2O _{2 -} > H ₂ O

As described above, the MEA has a structure in which a catalyst and a membrane are integrally joined to each other as an electrode. It is a core component that determines the performance of an electrochemical cell and is a major obstacle preventing the commercialization of an electrochemical cell including a fuel cell .

Typical methods for producing MEA are hot pressing method and adsorption reduction method. The hot pressing method is a method of bonding the catalyst fine particles and a binder such as PTFE (Polytetrafluoroethylene) to the ion exchange membrane by thermocompression bonding. However, since the membrane electrode assembly bonded by thermocompression bonding is formed by physically joining different phases having different physical properties, there is a problem in durability and the like. On the other hand, the adsorption-reduction method is to react the metal salt aqueous solution with a reducing agent on the surface of the electrode, thereby increasing the adhesion strength of the electrode catalyst and minimizing the contact resistance (interface resistance) between the electrode catalyst and the ion exchange membrane.

In the case of the conventional method of manufacturing an MEA using an adsorption-reduction method, a method in which a membrane is directly impregnated with an electrode material and then formed on the surface using a reducing agent, (The presence of a catalyst in the inside of the membrane, a front view and a side view of Comparative Example 1 in Fig. 3).

Thus, the conventional MEA structure has a problem that the amount of the electrode catalyst is used more than necessary. The reason for the problem is that diffusion of water, which is a reactant, into the catalyst layer and diffusion of oxygen generated from the catalyst to the outside are difficult, and diffusion of hydrogen or oxygen gas as a reactant into the catalyst layer And diffusion of water or the like generated in the catalyst to the outside is difficult.

Korea Patent No. 10-1357146 Korean Patent Publication No. 10-2008-0032962

The present invention has been developed in order to solve the problems of the prior art as described above, and it is an object of the present invention to provide an electrode catalyst layer of a fibrous web structure having a durability to reduce the amount of catalyst used in the electrode catalyst layer, The present invention provides a membrane electrode assembly for an electrochemical cell and a method of manufacturing the same.

In order to achieve the above object, the electrode catalyst layer of the web structure of the present invention is applied to an electrochemical cell, and the electrode catalyst layer has an open porous web in which fibers are arranged in a three-dimensional structure.

According to the present invention, the electrochemical cell is a fuel cell or a water electrolysis cell. Particularly, the fuel cell is preferably a PEMFC (Polymer Electrolyte Membrane Fuel Cell).

Further, according to the present invention, the fiber has a diameter of 0.005 to 5 mu m.

Further, according to the present invention, the web has a thickness of 1 to 20 mu m and has a porosity of 70 to 98% with respect to the total volume of the web.

The catalyst of the electrode catalyst layer may be platinum group metal such as platinum (Pt), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os) or iridium (Ir) ) Or an alloy of at least one of the platinum group metals and iron (Fe), cobalt (Co) or nickel (Ni).

According to the present invention, there is further provided a support for supporting the catalyst, wherein the support is a fluorine-based polymer electrolyte or a hydrocarbon-based polymer electrolyte having proton conductivity.

In order to achieve the above object, the membrane electrode assembly for an electrochemical cell of the present invention is characterized by having an electrode catalyst layer of a web structure configured as described above on the surface of the membrane.

In order to accomplish the above object, the present invention provides a method for manufacturing a membrane electrode assembly for an electrochemical cell, comprising the steps of: preparing a metal having an open pore structure in which fibers are arranged in a three- A second step of preparing the web by electrospinning the precursor prepared in the first step, a second step of preparing the web by impregnating a catalyst ion, And a fourth step of reducing and post-treating the polymer electrolyte membrane having the web prepared in the third step.

The electrode catalyst layer of the web structure of the present invention has a high effective porosity due to an open pore structure arranged in a three-dimensional structure, enables effective utilization of catalyst and mass transfer, and can realize remarkably improved performance of an electrochemical cell. Particularly, improved power density and water management ability are more effective than conventional electrochemical cells while reducing the amount of platinum used, thus realizing unit cell realization.

In addition, the electrode catalyst layer of the web structure of the present invention has an effect of reducing the electrolytic power consumption (or improving the output density in the case of the fuel cell), which is superior to the conventional electrochemical cell, Implementation of a chemical cell is possible.

In addition, the electrode catalyst layer of the web structure of the present invention is advantageous in that it does not require a carrier (carbon material used for supporting the metal catalyst) used in existing electrochemical cells and contributes to improvement in durability.

Meanwhile, the MEA having the electrode catalyst layer of the web structure of the present invention is easy to transfer materials and discharge gas, lowers the mass transfer resistance, and also removes the existing carrier, And has the advantage of enabling high-efficiency operation.

1 is a conceptual diagram of a general membrane electrode assembly constituting an electrochemical cell,
2 is a conceptual view of an electrode catalyst layer of a web structure according to an embodiment of the present invention,
FIG. 3 is a photograph of a structure of an electrode catalyst layer of a web structure according to the present invention and a conventional electrode catalyst layer,
FIG. 4 is a conceptual view illustrating a manufacturing process of an MEA having an electrode catalyst layer of the web structure shown in FIG. 2,
5 is a conceptual view of the principle of the electrospinning apparatus applied to the manufacturing process according to the present invention,
6 is a photograph showing a manufacturing process of a fiber using an electrospinning device applied to a manufacturing process according to the present invention,
FIG. 7 is a photograph showing the fiber formation conditions in the embodiment of the present invention,
8 is a scanning electron microscope (SEM) photograph of a web prepared using the precursor solution according to the present invention,
9 is a photograph of the reduction process and the final MEA according to the present invention,
10 is a front view and a side view of an MEA according to an embodiment of the present invention and a comparative example,
11 is a photograph of a unit cell for evaluating the MEA of Examples and Comparative Examples of the present invention,
FIG. 12 is a graph showing the results of electrolytic evaluation of Examples and Comparative Examples of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following detailed description of the operation principle of the preferred embodiment of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may unnecessarily obscure the subject matter of the present invention. The same reference numerals are used for portions having similar functions and functions throughout the drawings.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of an electrode catalyst layer of a web structure according to the present invention, a membrane electrode assembly for an electrochemical cell using the same, and a manufacturing method thereof will be described in detail with reference to the accompanying drawings.

2 is a conceptual view of an electrode catalyst layer of a web structure according to an embodiment of the present invention. As shown in FIG. 2, the electrode catalyst layer 204 of the MEA 202 in the form of a final product is formed of a web structure, and is formed of an electrochemical cell (a fuel cell, in particular, a polymer electrolyte membrane fuel cell Cell, PEMFC) or water electrolysis cell) as an anode or cathode catalyst layer.

Meanwhile, the electrode catalyst layer 204 of the web structure of the present invention may be formed directly on a polymer electrolyte membrane or a gas diffusion layer (GDL).

As the material of the catalyst 206 of the electrode catalyst layer 204 of the web structure according to the present invention, platinum (Pt), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Ir), or an alloy of iron (Fe), cobalt (Co), or nickel (Ni) with at least one of the platinum group metals as described above. On the other hand, it is preferable to use at least one metal or oxide selected from platinum, palladium, rhodium, ruthenium and iridium so that the material of the catalyst 206 is excellent in reactivity and can be used efficiently and stably for a long time .

As the support 208 for supporting the catalyst 206 according to the present invention, a fluorine-based polymer electrolyte having proton conductivity, a hydrocarbon-based polymer electrolyte, or the like may be used. Here, the support body 208 supports the catalyst 206 in a state in which the catalyst 206 is located.

The electrode catalyst layer 204 of the web structure according to the present invention has an advantage of having a macro pore structure. That is, when the electrode catalyst layer 204 has high specific surface area, low tortuosity, interconnected pores, and is introduced into the MEA catalyst of the electrochemical cell, the electrode catalyst layer 204 has a platinum catalyst layer having a conventional carbon- It has an improved mass transfer characteristic as compared with the existing catalyst layer.

More specifically, since the electrode catalyst layer of the web structure according to the present invention has a fiber shape, it has a very open and short diffusion path as compared with the structure of a conventional metal catalyst layer, and has improved material transport and improved conductivity. In addition, the catalytic reaction area where the electrode chemical reaction may occur increases the reaction speed. Further, by making it possible to reduce the thickness of the catalyst layer, unlike the existing catalyst layer, it is not necessary to include an ionomer. In addition, there is an integrated structure in which the metal catalyst particles are bound to prevent the loss of the metal catalyst particles.

3 is a SEM photograph of the front and side surfaces of the conventional MEA and the MEA of the present invention for comparing the structure of the electrode catalyst layer of the web structure according to the present invention and the conventional electrode catalyst layer, have.

That is, as shown in FIG. 3, the conventional MEA (Comparative Example 1) has a structure in which the catalyst layer is compact and reactants and products are in contact with the internal catalyst to make hydrogen hard, and the catalyst also penetrates into the inside of the membrane 1 < / RTI > part b) catalyst. On the contrary, the MEA of the present invention (Examples 1-3) shows that the pores are sufficiently formed in the catalyst layer and the catalyst is not penetrated into the inside of the membrane, so that the catalyst utilization can be very high.

Hereinafter, a method of manufacturing a membrane electrode assembly for an electrochemical cell having an electrode catalyst layer of a web structure according to the present invention will be described.

FIG. 4 is a conceptual view illustrating a manufacturing process of an MEA having an electrode catalyst layer of the web structure shown in FIG. 2. FIG. As shown in Fig. 4, a method for producing an MEA having an electrode catalyst layer of a web structure of the present invention is characterized in that a liquid electrolyte having an ion exchange ability for producing a web having an open pore structure in which fibers are arranged in a three- A second step of preparing a web by electrospinning the precursor prepared in the first step, a second step of preparing a precursor by impregnating the metal catalyst with a metal catalyst ion, A third step of transferring the web onto the surface of the polymer membrane to be electrolyzed, and a fourth step of reducing and post-treating the polymer electrolyte membrane having the web prepared in the third step.

Hereinafter, each step (first to fourth steps) will be described in detail.

Step 1

In the first step, a precursor for producing a fiber centered on an ionomer and an electrode catalyst precursor is prepared as a preliminary step for preparing an electrode catalyst layer of a web structure. Here, the precursor is prepared from a solvent, a catalyst-containing material, an electrolyte ionomer, a viscosity adjusting agent, and the like. On the other hand, when the precursor solution composed of the above-mentioned material has a non-solubility with respect to the organic solvent, the web can not be manufactured in the second step electrospinning process. Thus, the precursor solution of the present invention should be soluble in organic solvents.

On the other hand, as the precursor of the electrode catalyst used in the first step (the first and second electrochemical catalysts 112 and 116 in FIG. 1), in addition to platinum group elements of platinum, palladium, ruthenium, iridium, rhodium and osmium, A metal such as copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium and aluminum or an alloy thereof or an oxide or a double oxide may be used. However, it is preferable to use one or more metals or oxides selected from platinum, palladium, rhodium, ruthenium and iridium for excellent electrode reactivity and for efficient and stable long-term use of the electrode reaction. As the catalyst, chlorides or nitroxides of the above-mentioned metals having good solubility are suitable.

The electrolyte ionomer contained in the precursor may be a fluorine-based polymer electrolyte having proton conductivity, a hydrocarbon-based polymer electrolyte, or the like. As the fluorinated polymer electrolyte, for example, a Nafion (registered trademark) ionomer material of DuPont can be used. As the hydrocarbon-based polymer electrolyte, a sulfonated polyether ketone, a sulfonated polyether sulfone, a sulfonated polyether Ethersulfones, sulfonated polysulfides, ionomers such as sulfonated polyphenylene, and the like can be used. Among them, it is preferable to use the same material as the film to be transferred in the third step. Nafion is a sulfonated tetrafluoroethylene fluoropolymer-copolymer which is very stable against chemical attack. Nafion ionomer is a proton (H ⁺ ) like a polymer film. Conductive, superacid catalysts, and surfactants in the production of nanoparticles.

As the viscosity adjusting agent to be added to the precursor, a nonionic polymer, polyacrylic acid and the like can be used, and among them, polyacrylic acid (PAA) is preferable. PAA is a homopolymer of acrylic acid stable in strong acids and alkalis and is an atactic polymer that is easily soluble in water and alcohol.

Step 2

In the second step, the solution obtained in the first step is manufactured by using an electrospinning apparatus. 5 is a conceptual view of the principle of the electrospinning apparatus applied to the manufacturing process according to the present invention. The basic principle of an electrospinning device is to stretch the precursor under a high electric field to form it in the form of a fiber on a grounded target.

5, the electrospinning device includes a syringe pump (not shown in the drawings), a DC high voltage generator (not shown in the figure), nanofibers (fibers) that can push out a precursor having a liquid viscosity, And a target and the like for extracting the ink.

6 is a photograph showing a process of manufacturing a fiber using an electrospinning device applied to a manufacturing process according to the present invention. 6 (a) is a photograph in which the polymer solution at the end of the capillary nozzle before the electric field application is suspended and forming a hemispherical droplet, (b) shows a state in which the solution suspended at the end of the capillary is stretched when an electric field is applied, A jet of the solution is released. In FIG. 6 (c), the jet flows toward the target and the solvent evaporates while flying in the air, and the polymer continuous phase fibers are piled on the target. At this time, the trajectory of the jet may bend or change direction. FIG. 6 (d) is a photograph showing a process in which the jet is tapered while moving, and the initial one jet is divided into several smaller filaments. A photograph of the polymer nanofibers thus obtained is shown in Fig. 6 (e).

The polymer nanofibers are obtained by using the precursor in the first step. The main operating parameters are the solution characteristics (concentration, viscosity, surface tension), distance from the capillary tip to the target (collector plate) The results obtained from many trial and error inventors in the radiation environment and the like are shown in the examples.

The web of the present invention has a three-dimensionally connected web shape composed of a predetermined fiber, and the diameter of the fiber may range from 0.005 to 5 mu m. If the diameter of the fibers constituting the web is less than 0.005 mu m, the mechanical strength of the web may be lowered. If the diameter exceeds 5 mu m, the porosity of the porous nano-web may not be easily controlled.

In addition, the web of the present invention may be formed to have a thickness of 1 to 20 탆 by adjusting the injection amount of the electrospinning device. If the thickness of the web is less than 1 탆, the mechanical strength and the shape stability may be deteriorated, and if the thickness of the web exceeds 20 탆, the resistance loss may increase.

In addition, the web of this invention can have a porosity of 70-98% relative to the total volume of the web. If the porosity of the web is less than 70%, the diffusion resistance may be lowered, and if the porosity of the web is more than 98%, the mechanical strength and morphological stability may be deteriorated.

A polymer electrolyte membrane, a titanium foil, a Teflon sheet, or the like can be used as a target to emit the web, but there is no limitation, but a polymer electrolyte membrane is most preferable considering the interface resistance with the catalyst layer.

Step 3

The third step is a step of transferring the web obtained in the second step onto the polymer electrolyte membrane or diffusion layer.

The polymer electrolyte membrane to be transferred may be one having hydrogen ion (proton) conductivity, and fluorine-based polymer electrolytes and hydrocarbon-based polymer electrolytes may be used. Examples of the fluorinated polymer membrane include Nafion (registered trademark) of DuPont, Flemion (registered trademark) of Asahi Glass Co., Ltd., Aciplex (registered trademark) of Asahi Kasei Co., ), Gore Select (Gore Select, registered trademark) of Gore, and the like can be used. As the hydrocarbon-based polymer membrane, sulfonated polyether ketone, sulfonated polyether sulfone, sulfonated polyether ether sulfone, sulfonated polysulfide, An electrolyte membrane such as sulfonated polyphenylene may be used. Among them, it is preferable to use a Nafion (registered trademark) material of DuPont as a polymer film.

The process of transferring the first and second electrode layers to both surfaces of the film is as follows.

The web obtained in the second step is placed on both sides of the film as an electrode layer, and heat and pressure are applied by hot pressing under high temperature and pressure. In this case, the heat treatment temperature is set to 120 ° C or higher and 200 ° C or lower in consideration of the deformation of the components, and the heat treatment time is 1 minute to 30 minutes. The heat treatment pressure is 100kgf / 0 to 100 kgf / cm < 2 >). At this time, the thickness of the polymer electrolyte membrane is not limited, and the thickness of the web electrode layer is 0.1 to 1 mm, preferably 0.1 to 0.5 mm, as described above.

Step 4

In the fourth step, the polymer electrolyte membrane having the web electrode layer obtained in the third step is prepared as a final MEA.

In the preparation of the metal nanoparticles, the metal ions are reduced as shown in Scheme 7 by a reducing agent.

[Reaction Scheme 7]

xM ^{n +} + nxe ^- + reducing agent -> M ⁰ _n (cluster)

As the reducing agent, metal ions can be reduced by using alcohol, hydrazine, hydroxylamine, sodium borohydride or the like.

Hereinafter, embodiments according to the present invention will be described in detail. The presented embodiments are illustrative and not intended to limit the scope of the invention.

The conditions of Examples and Comparative Examples are shown in Table 1 below.

Example 1 Example 2 Example 3 Comparative Examples 1 and 2 target  Nafion membrane titanium Teflon Nafion membrane Whether it is a warrior process not needed need need not needed

Example 1. Preparation of a web structure directly on a Nafion membrane

( 1) Optimization of manufacturing conditions of polymer web

The precursors were prepared according to the ratio of polyethylene oxide (PEO) and perfluorosulfonic acid (PFSA, EW 1,100, hereinafter referred to as PFSA), H ₂ O and IPA Respectively.

The following Table 2 is an example of an experiment applied to web manufacture.

Condition
Preparation conditions of solution Weight ratio in solution PFSA / PEO weight ratio One 5 99/1 2 5 95/5 3 10 99/1

The result of an example of the polymer web prepared in conditions 1, 2 and 3 is shown in FIG. From this result, "Condition 3" was selected and optimum conditions were derived while varying the voltage, nozzle size, feed rate, and distance from the nozzle to the transfer target, which are parameters of the electrospinning condition.

parameter Electrospinning conditions Voltage 3.0 - 7.0 kV Solution feed rate 5 - 200 / / min Target to nozzle distance 5 - 6 cm Solution Properties Polymer concentration 15 - 25 wt% Alcohol Solvent methanol, ethanol, 2-propanol, 1-propanol PEO Concentration (wt%) 1 - 2 wt%

( 2) Production of metal catalyst web

All experiments were carried out under "Condition 3" obtained from the above production conditions of the polymer web.

Example 1 is for electrospinning a polyelectrolyte membrane, and conditions applied at this time are shown in Table 4 below.

Example 1 1-1 1-2 1-3 1-4 1-5 target  Nafion membrane Fiber layer thickness (injection amount) (μl / min) 20 40 80 80 160 Platinum Loading Amount (mg / cm ² ) 0.5 0.5 0.5 2 2

Step 1: Preparation of precursor solution

Nafion ionomer (PFSA), PEO, water, and alcohol were prepared as in "Condition 3", and a precursor solution was prepared by adding Pt (NH ₃ ) ₄ Cl ₂ compound to the solution to the amount of platinum loading.

Step 2: electrospinning

The web was prepared by the electrospinning conditions of "(1) Optimization of production conditions of polymer web" described above. The injection amount was adjusted to control the thickness of the web.

8 is a scanning electron micrograph (SEM) photograph of a web prepared using the precursor solution according to the present invention, which is a fibrous photograph obtained by spinning a precursor solution having a catalyst ion on the basis of "Condition 3 ". As a result, the size and thickness of the fibers (long fibers of 200 nm or less) were obtained as in the case of Fig. 7 (production of general polymer fibers in the absence of a catalyst precursor).

Step 3: Warrior

The web obtained in the second step was hot-pressed under the conditions of temperature, pressure and time as variables of 80 to 120 ° C, 0.5 to 3 Mpa, and 1 to 2 min.

Step 4: Reduction and post-treatment

The reducing solution was prepared by adjusting sodium hydroxide (NaOH) to pH 12-13, preparing sodium borohydride (NaBH ₄ ) at a certain concentration, dispersing it ten times, and treating the solution at 90 ° C for 10 hours, . After the reduction, 0.5M H ₂ SO ₄ was treated at 80 ° C for 5hr and pure water at 80 ° C for 1hr.

9 is a photograph showing the reduction process and the final MEA according to the present invention, showing the reduction process in the fourth step. 9 shows the reduction process in the reducing solution, and the bottom is a photograph of the final product obtained in the fourth step.

Physical evaluation of MEA (SEM measurement)

FIG. 10 is a front and side view of the MEA for the examples and comparative examples of the present invention, including SEM images of the front and side surfaces of the MEA after the final four steps of Examples 1-3. FIG.

Electrolytic performance evaluation

FIG. 11 is a photograph of a unit cell for evaluating the MEA according to the example of the present invention and the comparative example, wherein the MEA after the fourth step prepared in the example was kept at room temperature (27 占 폚) and 0.1 to 0.6 Lifting the a / cm ² current to 0.1A / cm ² was specific interval to a voltage. The electrolytic performance is shown in Fig. 12 in Examples 1-1, 1-2, and 1-3. FIG. 12 is a graph showing the results of electrolytic evaluation of Examples and Comparative Examples of the present invention.

Example 2: Transcription to a polymer electrolyte membrane after manufacturing a web on a titanium foil

The manufacturing conditions of the web are the same as in the first embodiment.

The conditions applied in Example 2 are shown in Table 5 below.

Example 2 2-1 2-2 2-3 target  Titanium foil (thickness 0.1mm) Fiber layer thickness (injection amount) (μl / min) 0.02 0.04 0.08 Platinum Loading Amount (mg / cm ² ) 0.5 0.5 0.5

Step 1 : Preparation of precursor solution

After the Nafion ionomer (PFSA), PEO, water and alcohol were prepared as in "Condition 3" as in Example 1, Pt (NH ₃ ) ₄ Cl ₂ compound was added to the solution to the amount of platinum loading to prepare a precursor solution Respectively.

Step 2: electrospinning

The web was prepared by electrospinning conditions of "(1) Optimization of production conditions of polymeric web" of Example 1 with a titanium foil (0.1 mm) as a target. The injection amount was adjusted to control the thickness of the web.

Step 3: Warrior

The web on the titanium foil obtained in the second step was hot-pressed on the polymer solid electrolyte membrane (Nafion 117) under the conditions of temperature, pressure, and time as a variable at 80 to 120 ° C, 0.5 to 3 Mpa, and 1 to 2 min.

Step 4: Reduction and post-treatment

The reduction conditions of Example 1 were the same.

Physical evaluation of MEA (SEM measurement)

FIG. 10 shows the front and side SEM images of the MEA after the final four steps of Example 2-2.

Electrolytic performance evaluation

The performance was evaluated in the same operating conditions of Example 1 and in the same electrolysis cell.

The electrolytic performance of Example 2 is shown in Fig. 12 as Examples 2-1 and 2-2.

Example 3 [0050] After the web was manufactured on a Teflon sheet, a polymer electrolyte membrane was transferred

The manufacturing conditions of the web are the same as in the first embodiment.

The conditions applied in Example 3 are shown in Table 6 below.

Example 3 3-1 3-2 3-3 target  Titanium foil (thickness 0.1mm) Fiber layer thickness (injection amount) (μl / min) 0.02 0.04 0.08 Platinum Loading Amount (mg / cm ² ) 0.5 0.5 0.5

Step 1: Preparation of precursor solution

After the Nafion ionomer (PFSA), PEO, water and alcohol were prepared as in "Condition 3" as in Example 1, Pt (NH ₃ ) ₄ Cl ₂ compound was added to the solution to the amount of platinum loading to prepare a precursor solution Respectively.

Step 2: electrospinning

The web was prepared by electrospinning conditions of "(1) Optimizing the production conditions of the polymeric web" of Example 1 with a Teflon sheet (0.1 mm) as a target. The injection amount was adjusted to control the thickness of the web.

Step 3: Warrior

The web on the Teflon sheet obtained in the second step was hot-pressed on the polymer solid electrolyte membrane (Nafion 117) under the conditions of temperature, pressure, and time as variables of 80 to 120 ° C, 0.5 to 3 Mpa, and 1 to 2 min.

Step 4: Reduction and post-treatment

The reduction conditions of Example 1 were the same.

Physical evaluation of MEA (SEM measurement)

10 shows the front and side SEM images of the MEA after the final four steps of Example 3-2.

Electrolytic performance evaluation

The performance was evaluated in the same operating conditions of Example 1 and in the same electrolysis cell.

The electrolytic performance of Example 3 is shown in Fig. 12 as Examples 3-1 and 3-2.

≪ Comparative Example 1 and Comparative Example 2 > A membrane-electrode assembly subjected to electroless plating

The comparative examples were prepared based on the electroless plating method as shown in Table 7.

Comparative Example One 2 Platinum Loading Amount (mg / cm ² ) 0.5 4

MEA Manufacturing Method

MEA was fabricated by electroless plating (Electro-less Plating) method. The loading amount of platinum was based on the conventional loading amount of 4.

In Example 1, a precursor solution was prepared by adding a Pt (NH ₃ ) ₄ Cl ₂ compound to a water and alcohol solution in accordance with the amount of platinum loading, and then the Nafion polymer solid electrolyte membrane was impregnated at 80 to 120 ° C. overnight. After impregnation and washing, the Pt ion is reduced by treatment with the reducing solution (PH 12-13, borohydride sodium (NaBH ₄ )) of the fourth step of Example 1 at 90 ° C for 10 hours. At the end of the reduction process, 0.5 M H ₂ SO ₄ is treated at 80 ° C for 5 hr and pure water at 80 ° C for 1 hr.

Physical evaluation of MEA (SEM measurement)

FIG. 10 shows the front and side SEM images of the MEA after the final stage of Comparative Example 1. FIG.

Electrolytic performance evaluation

The performance was evaluated in the same operating conditions of Example 1 and in the same electrolysis cell.

Fig. 12 shows Comparative Example 1 and Comparative Example 2.

Conclusions for Examples 1, 2, 3 and Comparative Examples 1, 2

(1) Based on the performance of Comparative Examples 1 and 2, it was confirmed that the MEAs of Examples 1, 2 and 3 were applicable as MEAs.

(2) Compared with Comparative Example 2 (based on the amount of platinum loaded at present), it was confirmed that the MEAs of Examples 1, 2 and 3 were applicable as MEA even when the amount of platinum was applied at a level of 1/4.

(3) According to Examples 1 and 2, the amount of platinum used was greatly reduced, and the performance was improved.

The electrode catalyst layer of the web structure of the present invention, the membrane electrode assembly for an electrochemical cell using the same, and the manufacturing method thereof have been described above with reference to the accompanying drawings, which illustrate the best preferred embodiments of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. Examples or modifications will also fall within the scope of the claims of this invention.

Claims (10)

In the electrode catalyst layer for an electrochemical cell,
Wherein the electrode catalyst layer has a web having an open porous structure in which fibers are arranged in a three-dimensional structure. The method according to claim 1,
Wherein the electrochemical cell is a fuel cell or a water electrolysis cell. The method of claim 2,
Wherein the fuel cell is a polymer electrolyte membrane fuel cell (PEMFC). The method according to claim 1,
Wherein the fibers have a diameter of 0.005 to 5 mu m. The method according to claim 1,
Wherein the web has a thickness of 1 to 20 占 퐉. The method according to claim 1,
Wherein the web has a porosity of 70-98% relative to the total volume of the web. The method according to claim 1,
The catalyst of the electrode catalyst layer may be a platinum group metal such as platinum (Pt), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os) or iridium (Ir) Characterized in that the electrode catalyst layer of the web structure is composed of at least one kind of metal and an alloy of iron (Fe), cobalt (Co) or nickel (Ni). The method of claim 7,
Further comprising a support for supporting the catalyst,
Wherein the support is a fluorine-based polymer electrolyte having a proton conductivity or a hydrocarbon-based polymer electrolyte. A membrane electrode assembly for an electrochemical cell,
A membrane electrode assembly for an electrochemical cell, characterized by having an electrode catalyst layer of a web structure according to any one of claims 1 to 8 on the surface of the membrane. A method of manufacturing a membrane electrode assembly for an electrochemical cell,
A first step of preparing a precursor by impregnating a metal catalyst ion into a liquid electrolyte having an ion exchange ability to produce a web having an open pore structure in which fibers are arranged in a three-dimensional structure;
A second step of electrospinning the precursor prepared in the first step to produce the web;
A third step of transferring the web prepared in the second step to the surface of the electrolyte polymer membrane, and
And a fourth step of reducing and post-treating the electrolyte polymer membrane having the web prepared in the third step. ≪ RTI ID = 0.0 > 11. < / RTI >

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