KR101153027B1 - Electrode for fuel cell comprising ink lines with different directions, Method of preparing the same, Membrane electrode assembly and Fuel cell comprising the same - Google Patents

Abstract

The present invention relates to a fuel cell electrode including the ink line in a different direction, a method for manufacturing the same, and a membrane electrode assembly and a fuel cell including the same. An electrode for a fuel cell of the present invention is a fuel cell electrode including a catalyst layer formed by stacking a plurality of catalyst parts, wherein each catalyst part includes an electrolyte such that catalyst particles and ink droplets for forming a catalyst part in which a catalyst ion and a polymer ionomer are dispersed in a solvent are continuously connected. It consists of a plurality of parallel ink lines or ink spot lines formed by spraying the film or gas diffusion layer in an inkjet method, the plurality of ink lines or ink spot lines forming the catalyst portion are spaced apart from each other, the upper and lower catalyst portion The ink line or ink spot line is different from the ink line or ink spot line in the longitudinal direction. In the fuel cell electrode of the present invention, a plurality of pores are uniformly dispersed in the catalyst layer, so that fluid mobility is excellent.

Fuel cell, catalyst layer, ink line

Description

Electrode for fuel cell comprising ink lines with different directions, Method of preparing the same, Membrane electrode assembly and Fuel cell comprising the same}

The present invention relates to a fuel cell electrode including the ink line in a different direction, a method for manufacturing the same, and a membrane electrode assembly and a fuel cell including the same. More specifically, an electrode for a fuel cell including an ink line in a different direction, which can be used for distributed power plants, cogeneration plants, pollution-free automobile power supplies, business power supplies, household power supplies, mobile device power supplies, and the like, and a method of manufacturing the same Membrane electrode assembly and fuel cell.

Recently, as the depletion of existing energy resources such as oil and coal is predicted, interest in energy that can replace them is increasing. As one of the alternative energy sources, the fuel cell is particularly attracting attention due to its advantages such as high efficiency, no pollutants such as NO _x and SO _x , and abundant fuel used.

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

In a fuel cell, the most basic unit for generating electricity is a membrane electrode assembly (MEA), which is composed of an electrolyte membrane and anode and cathode electrodes formed on both sides of the electrolyte membrane. Referring to FIG. 1 and Reaction Formula 1 (Reaction formula of a fuel cell when hydrogen is used as a fuel) showing the electricity generation principle of a fuel cell, an oxidation reaction of a fuel occurs at an anode electrode, and hydrogen ions and electrons are generated. The electrolyte moves through the electrolyte membrane to the cathode electrode, where water is generated by reaction between oxygen (oxidant) and hydrogen ions transferred through the electrolyte membrane and electrons. This reaction causes the movement of electrons in the external circuit.

The ^{_{anode: H 2 → 2H + + 2e}} -

^{_{Cathode: 1 / 2O 2 + 2H +}} + 2e - → H 2 O

Total Reaction Formula: H ₂ + 1 / 2O ₂ → H ₂ O

Referring to FIG. 2, which shows a general configuration of a membrane electrode assembly for a fuel cell, the membrane electrode assembly of a fuel cell includes an anode electrode and a cathode electrode disposed to face each other with an electrolyte membrane and an electrolyte membrane interposed therebetween. It consists of a catalyst layer and a gas diffusion layer. The gas diffusion layer is composed of an electrode substrate and a microporous layer formed thereon.

Various methods of forming the aforementioned catalyst layer are known in the art. For example, a screen printing method, a spray coating method, a doctor blade method, a roll coating method, or a slit die coating method and the like are introduced.

However, in the fuel cell, the catalyst layer not only serves to supply fuel gas and oxidant necessary to cause a reaction, and discharge moisture as a result of the reaction, but also has a function of delivering protons through the moisture contained therein. Since the catalyst layer forming method described above forms the catalyst layer as a whole in the same form, it is impossible to design and implement an internal structure to facilitate mass transfer in the catalyst layer.

As a solution to this problem, the inkjet printing method has recently attracted attention as a method for forming a catalyst layer. The inkjet method can adjust the ink injection to some extent, and thus has an advantage that a catalyst layer having a specific pattern can be realized. Therefore, various catalyst layers have been proposed to facilitate the supply and discharge of fuel or moisture by using this feature of the inkjet method.

For example, Japanese Laid-Open Patent Publication No. 2007-179792 discloses an electrode for a fuel cell having a pore passing through a catalyst layer and a gas diffusion layer.

However, there is still an urgent need to solve the above problems and to develop an electrode for a fuel cell having a catalyst layer having improved porosity and pore distribution.

Accordingly, an object of the present invention is to provide a fuel cell electrode which can improve the performance of a fuel cell as a result of the uniform distribution of pores in the catalyst layer to facilitate mass transfer.

In order to solve the above problems, the fuel cell electrode of the present invention is a fuel cell electrode including a catalyst layer formed by stacking a plurality of catalyst parts, wherein each of the catalyst parts is for forming a catalyst part in which catalyst particles and polymer ionomers are dispersed in a solvent. It consists of a plurality of parallel ink lines or ink spot lines formed by spraying the ink film or the ink diffusion method to the electrolyte membrane or the gas diffusion layer so that the ink droplets are continuously connected, the plurality of ink lines or ink spot lines forming the catalyst portion are spaced apart from each other The length of the ink line or the ink spot line is different from the ink line or the ink spot line of the upper and lower catalyst parts. As shown in FIG. 3 and FIG. 4, the present invention comprises a plurality of spaced ink lines 11 and 12 or ink spot lines having different directions for each stacked catalyst portion, thereby providing sufficient voids in the catalyst layer 13. At the same time, each pore is uniformly dispersed in the catalyst layer, which is very good in mass transfer performance.

The parallel ink line or ink spot line forming each of the above-described catalyst parts is preferably not in contact with each other, for example, but may be spaced up to twice the width of each line, but is not limited thereto.

In addition, the present invention (S1) by spraying the ink for forming the catalyst portion in a predetermined position of the electrolyte membrane or the gas diffusion layer in an inkjet method so that ink droplets are continuously connected to form a plurality of parallel ink lines or ink spot lines spaced apart from each other To form a first catalyst portion; (S2) forming a plurality of ink lines or ink spot lines on the formed first catalyst portion in the same manner as in the step (S1), but a plurality of ink lines or ink spot lines in a length direction different from that of the first catalyst portion Forming an ink line or an ink spot line to form a second catalyst part; And (S3) repeating the step (S2) to form a catalyst layer having a predetermined thickness by repeating the step (S2) so that an ink line or an ink spot line in a longitudinal direction different from the ink line or ink spot line of the lower catalyst layer is formed. It provides a method of manufacturing an electrode for a fuel cell comprising the step.

In the fuel cell electrode manufacturing method of the present invention, the injection of the ink droplets may be performed in a heat treatment state as necessary.

The electrode of the present invention described above can be used in membrane electrode assemblies and fuel cells.

In the fuel cell electrode of the present invention, since the number of pores is maximized and the distribution thereof is uniformly formed, the performance of the battery is improved. In addition, since the method of manufacturing the electrode for a fuel cell of the present invention uses an inkjet injection method, it is possible to control the position of the ink to be injected, thereby making it possible to manufacture an electrode having a uniform pore distribution.

Hereinafter, the electrode for a fuel cell of the present invention will be described in detail according to the manufacturing method thereof. The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

First, a plurality of parallel ink lines or ink spot lines spaced apart from each other are formed by spraying a catalyst for forming catalyst ink at a predetermined position of an electrolyte membrane or a gas diffusion layer in an inkjet manner so that ink droplets are continuously connected to form a first catalyst portion. (S1).

Catalyst forming ink according to the present invention can be used without limitation catalyst forming ink used in the art. For example, the catalyst forming ink may include a metal catalyst supported on a metal catalyst or a carbon-based support; Polymer ionomers; And a solvent.

The metal catalyst is typically selected from the group consisting of platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy, platinum-molybdenum alloy, platinum-rhodium alloy and platinum-transition metal alloy. One or a mixture of two or more may be used, but is not limited thereto.

The carbonaceous support may include graphite (graphite), carbon black, acetylene black, denka black, canyon black, activated carbon, mesoporous carbon, carbon nanotubes, carbon nanofibers, carbon nanohorns, and carbon nanorings. One or a mixture of two or more selected from the group consisting of carbon nanowires, fullerenes (C60), and super P may be preferred, but is not limited thereto.

As the polymer ionomer, sulfonated polymers such as nafion ionomer or sulfonated polytrifluorostyrene may be representatively used. The content of the polymer ionomer in the catalyst forming ink may be appropriately adjusted according to the type and use of the fuel cell to be applied, for example, 0.1 to 30 parts by weight based on 100 parts by weight of the metal catalyst. Within this range, while the ionomer does not excessively cover the catalyst layer to facilitate the reaction between the catalyst and the fuel, the ion transport passage in the catalyst layer is properly formed can be the smoothest movement of ions.

As the solvent, any one or a mixture of two or more selected from the group consisting of water, butanol, iso propanol, methanol, ethanol, n-propanol, n-butyl acetate, and ethylene glycol may be preferably used. It is not limited. The content of the solvent in the catalyst forming ink may be appropriately adjusted according to the type of fuel cell, the manufacturing environment, and the use environment. For example, the amount may be 100 to 5000 parts by weight based on 100 parts by weight of the metal catalyst, but is not limited thereto. When the content of the solvent is in the above range, the viscosity of the catalyst for forming the catalyst portion is maintained very appropriately so that it is possible to form a uniform catalyst layer as well as excellent dispersibility of the catalyst particles during coating and coating can be performed with a minimum number of times. The productivity is also excellent.

After preparing the above-described ink, a plurality of parallel ink lines or ink spot lines spaced from each other are formed by spraying ink droplets at predetermined positions of the electrolyte membrane or the gas diffusion layer so that the ink droplets for forming the catalyst portion are continuously connected. .

Since the ink jet injection method can adjust the injection position of the ink droplets very precisely using related software, the ink for forming a catalyst portion can be jetted in droplet units at a predetermined position on the electrolyte membrane or the gas diffusion layer.

In this case, when a portion of the ejected ink droplets overlap each other, a line is formed. When the ink droplets contact each other, a spot formed of ink droplets forms a spot line forming a line. 3 and 4 schematically show the form in which the ink line 11 is formed.

In addition, a plurality of parallel ink lines or ink spot lines forming the catalyst unit according to the present invention is characterized in that spaced at a predetermined interval. The spacing between these lines forms pores in the catalyst layer as a plurality of catalyst units are later stacked. The interval between the lines may be appropriately selected according to the type and use of the fuel cell, and may be, for example, up to twice the width of each line, but is not limited thereto. If the distance between the lines is too far, the amount of catalyst in the catalyst layer is insufficient to reduce the reaction efficiency and the adhesion between the electrolyte membrane and the catalyst layer may be lowered. Therefore, it is possible to maintain sufficient performance of the battery by securing sufficient voids for mass transfer without lowering the reaction efficiency and adhesion in the interval range.

When the injection of the ink droplets directly contacting the electrolyte membrane or the gas diffusion layer at the designated position of the electrolyte membrane or the gas diffusion layer is completed, as shown in FIGS. 3 and 4, on the electrolyte membrane 201 or the gas diffusion layer 208. A first catalyst part consisting of a plurality of ink lines or ink spot lines 11 is formed.

Next, a plurality of ink lines or ink spot lines are formed on the formed first catalyst portion in the same manner as in the step (S1), but a plurality of ink lines or ink spot lines are formed in a length direction different from the ink lines or ink spot lines of the first catalyst portion. An ink line or an ink spot line is formed to form a second catalyst part (S2).

By adjusting the advancing direction of the ejection port for ejecting ink or adjusting the position of the electrolyte membrane or gas diffusion layer through which the ink is ejected, the catalyst is formed in a longitudinal direction different from the longitudinal direction of the ink line or ink spot line 11 formed in the previous step. New ink lines or ink spot lines 12 may be formed by spraying the secondary forming ink.

When the injection of the ink droplets for forming the catalyst portion for forming the second catalyst portion is finished, as shown in FIGS. 3 and 4, an ink line having a line length different from that of the first catalyst portion on the first catalyst portion or The second catalyst part formed of the ink spot line 12 is formed.

The longitudinal direction of the line of the line of the first catalyst portion and the longitudinal direction of the line of the line of the second catalyst portion only need to be different from each other and are not limited to a specific angle. For example, the length direction of the lines of the respective catalyst units may be perpendicular to each other, but is not limited thereto.

In order to form a catalyst layer having a predetermined thickness, the step (S2) is repeated to stack a plurality of catalyst parts (S3).

According to this injection method, as shown in FIGS. 3 and 4, it is possible to form a catalyst layer 13 in which ink lines or ink spot lines 11 and 12 having different longitudinal directions are alternately repeatedly stacked. The thickness of the catalyst layer may be determined as necessary, and for example, the thickness of the catalyst layer used in the art may be adopted. Typically, it may be 5 ~ 50㎛. The performance of the fuel cell in the above range can be very excellent.

In addition, in the case where ink droplets are sprayed by the inkjet method according to the present invention in each of the above steps, ink may be sprayed in a heat treatment state to promote drying of the sprayed ink droplets. Rapid drying of the ink droplets can have a better effect on the formation of voids in the catalyst layer. The specific heat treatment temperature may be appropriately selected depending on the type of fuel cell or the manufacturing environment, and may be, for example, 60 ° C. to 70 ° C., but is not limited thereto. The sprayed ink droplets can form a line very efficiently without filling the space between the lines of the lower catalyst part in the temperature range.

According to the above-described method, an electrode for a fuel cell comprising a catalyst layer formed by stacking a plurality of catalyst parts, wherein each catalyst part includes an electrolyte membrane or a catalyst particle so that catalyst particles and ink droplets for forming a catalyst part in which a polymer ionomer is dispersed in a solvent are connected in series. It consists of a plurality of parallel ink lines or ink spot lines formed by jetting the gas diffusion layer in an inkjet method, the plurality of ink lines or ink spot lines forming the catalyst portion are spaced apart from each other, the ink line of the upper and lower catalyst portion Alternatively, an electrode for a fuel cell having an ink spot line and an ink line or an ink spot line having a different length direction may be manufactured.

In the fuel cell electrode of the present invention, a plurality of spaced parallel ink lines or ink spot lines are alternately stacked in the catalyst layer of the electrode in different longitudinal directions, thereby greatly increasing the voids in the catalyst layer, and the distribution thereof. The fact that it is uniform and can improve the performance of the battery can be sufficiently predicted by those skilled in the art without any separate experiment.

As described above, the catalyst layer according to the present invention may be formed on the electrolyte membrane or the gas diffusion layer and used in the manufacture of the membrane electrode assembly for a fuel cell of the present invention.

As shown in FIG. 2, the fuel cell membrane electrode assembly of the present invention includes an electrolyte membrane 201; And an anode electrode and a cathode electrode positioned to face each other with the electrolyte membrane 201 interposed therebetween. The anode electrode and the cathode electrode includes a gas diffusion layer and a catalyst layer (203, 205), the gas diffusion layer for a fuel cell of the present invention is a substrate (209a, 209b) and the microporous layer (207a, 207b) formed on one surface of the substrate It may include.

As the electrolyte membrane of the present invention, an electrolyte membrane used in the art may be used without limitation, for example, perfluorosulfonic acid polymer, hydrocarbon polymer, polyimide, polyvinylidene fluoride, polyether sulfone, polyphenylene sulfide, A polymer selected from the group consisting of polyphenylene oxide, polyphosphazine, polyethylene naphthalate, polyester, doped polybenzimidazole, polyetherketone, polysulfone, and acids and bases thereof may be used, but is not limited thereto. Does not.

The gas diffusion layer of the present invention acts as a current conductor between the electrolyte membrane and the catalyst layer and becomes a passage of the reactant gas and the product water. Therefore, the gas diffusion layer has a porous (20-90%) structure to allow gas to pass through well.

As the gas diffusion layer of the present invention, a gas diffusion layer used in the art may be used without limitation, and may include a conductive substrate selected from the group consisting of carbon paper, carbon cloth, and carbon felt. The gas diffusion layer may further include a microporous layer formed on one surface of the conductive substrate, and the microporous layer may include a carbonaceous material and a fluorine resin.

Examples of the carbon-based material include graphite (graphite), carbon black, acetylene black, denka black, canyon black, activated carbon, mesoporous carbon, carbon nanotubes, carbon nanofibers, carbon nanohorns, carbon nanorings, carbon nanowires, One or a mixture of two or more selected from the group consisting of fullerenes (C60) and super P may be used, but is not limited thereto.

The fluororesin may be polytetrafluoroethylene, polyvinylidene fluoride (PVdF), polyvinyl alcohol, cellulose acetate, copolymer of polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) or styrene-butadiene rubber One or a mixture of two or more selected from the group consisting of (SBR) may be used, but is not limited thereto.

The thickness of the gas diffusion layer may be appropriately adopted as necessary, for example, may be 100 ~ 400㎛, but is not limited thereto. If the thickness is too thin, the electrical contact resistance between the catalyst layer and the separator is large and does not have enough force for compression. If the thickness is too thick, it is difficult to move the reactant gas, so the thickness should be maintained at an appropriate level.

At this time, the catalyst layer is formed on the microporous layer of the gas diffusion layer.

The present invention also provides a fuel cell comprising the membrane electrode assembly of the present invention. 5 is a view schematically showing a fuel cell according to an embodiment of the present invention. Referring to FIG. 5, the fuel cell of the present invention includes a stack 200, a fuel supply unit 400, and an oxidant supply unit 300.

The stack 200 includes one or more membrane electrode assemblies of the present invention, and when two or more membrane electrode assemblies are included, the stack 200 includes a separator interposed therebetween. The separator is electrically connected to the membrane electrode assemblies. It serves to prevent fuel loss and to deliver externally supplied fuel and oxidant to the membrane-electrode assembly.

The fuel supply unit 400 serves to supply fuel to the stack, and includes a fuel tank 410 for storing fuel and a pump 420 for supplying fuel stored in the fuel tank 410 to the stack 200. Can be. The fuel may be a gas or liquid hydrogen or hydrocarbon fuel, examples of the hydrocarbon fuel may be methanol, ethanol, propanol, butanol or natural gas.

The oxidant supply unit 300 serves to supply an oxidant to the stack. Oxygen is typically used as the oxidant, and may be used by injecting oxygen or air into the pump 300.

1 is a schematic diagram for explaining the principle of electricity generation of a fuel cell.

2 is a view schematically showing a structure of a membrane electrode assembly for a general fuel cell.

3 is a cross-sectional view schematically showing that the ink for forming a catalyst portion is injected into an electrolyte membrane or a gas diffusion layer according to the present invention to form a plurality of catalyst portions.

4 is a plan view schematically showing that the ink for forming a catalyst portion is injected into an electrolyte membrane or a gas diffusion layer according to the present invention to form a plurality of catalyst portions.

5 is a view schematically showing an example of a fuel cell according to the present invention.

Claims (14)

A fuel cell electrode comprising a catalyst layer formed by stacking a plurality of catalyst parts, wherein each of the catalyst parts includes: It consists of a plurality of parallel ink lines or ink spot lines formed by spraying the catalyst particles and the polymer ionomer dispersed in the solvent, ink droplets formed in the ink jet method to the electrolyte membrane or the gas diffusion layer so that the ink droplets are continuously connected, A plurality of ink lines or ink spot lines forming the catalyst portion are spaced apart from each other, the ink line or ink spot line of the upper and lower catalyst portion is different from the ink line or ink spot line in the longitudinal direction. The method of claim 1, The plurality of parallel ink lines or ink spot lines forming each of the catalyst portion is a fuel cell electrode, characterized in that the distance between the lines up to twice the width of each line. The method of claim 1, The length direction of the ink line or ink spot line of each of the catalyst portion is perpendicular to the length direction of the ink line or ink spot line of the upper and lower catalyst portion. The method of claim 1, The catalyst layer formed by stacking the plurality of catalyst parts has a thickness of 5 ~ 50㎛ electrode for fuel cells. The method of claim 1, The electrolyte membrane is a perfluorosulfonic acid polymer, a hydrocarbon-based polymer, polyimide, polyvinylidene fluoride, polyether sulfone, polyphenylene sulfide, polyphenylene oxide, polyphosphazine, polyethylene naphthalate, polyester, doped polybenz An electrode for a fuel cell, characterized in that the polymer is selected from the group consisting of imidazole, polyether ketone, polysulfone, and acids and bases thereof. The method of claim 1, The gas diffusion layer is a conductive substrate selected from the group consisting of carbon paper, carbon cloth and carbon felt; Carbon-based materials; And a fluorine-based resin. (S1) the first catalyst portion is formed by spraying a catalyst for forming the catalyst portion at a predetermined position of the electrolyte membrane or the gas diffusion layer in an inkjet manner so that ink droplets are continuously connected to each other to form a plurality of parallel ink lines or ink spot lines spaced apart from each other. Forming; (S2) forming a plurality of ink lines or ink spot lines on the formed first catalyst portion in the same manner as in the step (S1), but a plurality of ink lines or ink spot lines in a length direction different from the ink lines or ink spot lines of the first catalyst portion Forming an ink line or an ink spot line to form a second catalyst part; And (S3) repeating step (S2) to form a catalyst layer having a predetermined thickness by repeating the step (S2) to form an ink line or an ink spot line in a length direction different from the ink line or ink spot line of the lower catalyst layer. Method for producing an electrode for a fuel cell comprising a. The method of claim 7, wherein The catalyst portion forming ink may be a metal catalyst supported on a metal catalyst or a carbon-based support; Polymer ionomers; And a solvent. A method of manufacturing an electrode for a fuel cell, comprising: a solvent; The method of claim 7, wherein Parallel ink line or ink spot line forming each of the catalyst portion is a method of manufacturing a fuel cell electrode, characterized in that the interval between the lines up to twice the width of each line. The method of claim 7, wherein The length direction of the ink line or the ink spot line of each of the catalyst portion is perpendicular to the length direction of the ink line or ink spot line of the upper and lower catalyst portion. The method of claim 7, wherein The thickness of the catalyst layer is a manufacturing method of the electrode for a fuel cell, characterized in that 5 to 50㎛. The method of claim 7, wherein The injection of the ink droplets is a fuel cell electrode manufacturing method, characterized in that performed in a heat treatment state. Electrolyte membrane; And an anode electrode and a cathode electrode formed between the electrolyte membrane and having a catalyst layer and a gas diffusion layer, respectively. The anode electrode or the cathode electrode is a fuel cell membrane electrode assembly, characterized in that the electrode for fuel cells according to any one of claims 1 to 6. A stack comprising at least one membrane electrode assembly according to claim 13 and a separator interposed between the membrane electrode assemblies; A fuel supply unit supplying fuel to the stack; And A fuel cell comprising an oxidant supply unit for supplying an oxidant to the stack.

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