KR101728206B1 - Separator for fuel cell and fuel cell comprising the same - Google Patents

Abstract

[0001] The present invention relates to a separator for a fuel cell and a fuel cell including the separator. In the separator for a fuel cell according to the present application, a channel channel for fluid movement is provided on at least one surface of the separator, And a protrusion-shaped structure is provided on at least a part of the inner surface of the protrusion.

Description

TECHNICAL FIELD [0001] The present invention relates to a separator for a fuel cell and a fuel cell including the separator.

The present invention relates to a separator for a fuel cell and a fuel cell including the same.

2. Description of the Related Art In recent years, due to rapid diffusion of portable electronic devices and wireless communication devices, much attention and research have been made on the development of a fuel cell as a portable power source battery, a fuel cell for a pollution-free vehicle, and a fuel cell for power generation as a clean energy source.

Fuel cells are energy conversion devices that convert the chemical energy of a fuel directly into electrical energy. That is, a fuel cell uses a fuel gas and an oxidizing agent and generates electricity using electrons generated during the oxidation / reduction reaction. As a result, the fuel cell has a high energy efficiency and an environment- Research and development.

PEMFC (Polymer Electrolyte Membrane Fuel Cell) is attracting attention as a portable, automotive, and household power source because of its advantages such as low operating temperature, leakage problem caused by the use of solid electrolyte, and quick driving. In addition, it is a high-output fuel cell having a higher current density than other types of fuel cells, and is operated at a temperature of less than 100 ° C, has a simple structure, has a fast start-up and response characteristics, and has excellent durability. Can be used as fuel. In addition, miniaturization can be achieved with a high output density, and research on a portable fuel cell continues.

The unit cell structure of such a fuel cell has a structure in which an anode and a cathode are coated on both sides of an electrolyte membrane composed of a polymer material, which is called a membrane electrode assembly (MEA). This membrane electrode assembly (MEA) is composed of a cathode, an anode, and an electrolyte membrane, that is, an ion conductive electrolyte membrane, where electrochemical reaction of hydrogen and oxygen takes place. In connection with the electricity generating principle of the fuel cell, the oxidation reaction of the fuel occurs at the anode, and hydrogen ions and electrons are generated. The hydrogen ions move to the cathode through the electrolyte membrane, and at the cathode, And electrons react with each other to produce water. This reaction causes electrons to migrate to the external circuit.

Specifically, the porous catalyst layer (also referred to as a gas diffusion layer) is attached to both sides of the polymer electrolyte membrane, and the raw material is supplied to the catalyst layer and the unreacted material or the reaction And the electrode separation plate facing the catalyst layer is in close contact with the flow path for discharging the product.

Therefore, the supply of the raw material through the flow path of the electrode separator and the discharge of unreacted materials / reaction products must be smoothly performed, so that the operating performance and lifetime of the fuel cell can be improved. For example, when the drainage of the reaction product (mainly water) from the cathode is not smooth, a phenomenon called so-called cathode water flooding occurs, thereby disturbing the mass transfer of the air supplied to the stack Resulting in degraded operating performance of the stack and shortened life span.

Such drainage failure may occur not only in the flow path of the electrode separator but also in the flow path of the distribution header communicating the flow path of the plurality of separation plates to the discharge port.

Korean Patent Publication No. 10-2011-0059029

There is a need in the art for a separator for a fuel cell which can be manufactured by a simple process and has excellent characteristics and a fuel cell including the same.

[0002]

Wherein a channel channel for fluid movement is provided on at least one surface in a concave shape,

And a protruding structure is provided on at least a part of the inner surface of the flow channel.

The present application also provides a fuel cell including the separator for a fuel cell.

The separator for a fuel cell according to an embodiment of the present application can have a venturi effect of a fluid by including a protruding structure in at least a part of the inner surface of the channel channel to thereby exhibit a fluid effect such as fuel, It is possible to increase the flowability of the fluid.

In addition, the separation plate according to one embodiment of the present application can prevent the phenomenon of stagnation of fluid such as fuel, moisture and the like, thereby improving the performance of the fuel cell.

1 to 3 are schematic views showing a conventional separation plate for a fuel cell.
4 to 6 are schematic views of a separator for a fuel cell according to an embodiment of the present application.

The present application will be described in more detail below.

PEMFC (Polymer electrolyte membrane fuel cell) is a fuel cell that uses gas such as hydrogen and oxygen as a fuel, a fuel cell that uses liquid fuel as DMFC (direct methanol fuel cell), electrochemical reaction of fuel and oxygen In the case of a fuel cell or the like in which water is generated, the shape and pattern of the flow channel of the separator plate are important factors for enhancing fuel supplyability and discharging water. In the case of a conventional separator for a fuel cell, it was general to manufacture the separator in a flat form at a depth of about 1 mm.

The conventional separation plate for a fuel cell is schematically shown in Figs. 1 and 2. Fig. More specifically, FIG. 1 schematically shows the shape of a conventional separator for a fuel cell, and FIG. 2 schematically shows a flow of a fluid such as fuel, moisture and the like in a conventional separator for a fuel cell. 3 is a schematic vertical cross-sectional view of a channel channel of a conventional separator for a fuel cell.

However, since the shape of the channel channel of the conventional separation plate for a fuel cell has a flat shape, there is a limit to increase the flowability of the fluid such as fuel, moisture and the like, and congestion of the fluid There is a problem that is highly likely.

According to an embodiment of the present invention, a separation plate for a fuel cell is provided with a channel channel for moving fluid on at least one surface thereof, and a protrusion-type structure is provided on at least a part of the inner surface of the channel channel .

In particular, the inner surface of the channel channel may have a bottom surface and two opposite side surfaces, and the protruding structure may be provided in at least a part of the side surface of the channel channel. At this time, the protruding structure may be provided so as to be symmetrical with respect to two side surfaces of the flow channel, but the present invention is not limited thereto. As described above, a configuration in which the protruding structure is provided so as to be symmetrical with respect to the two side surfaces of the channel channel is schematically shown in FIG.

The size of the protrusion-shaped structure provided on the side surface of the flow channel may be 50% or less of the thickness of the flow channel, and may be 50% or less of the width of the flow channel.

In addition, the projection-shaped structure may be further provided on the bottom surface of the flow channel.

According to the present application, the velocity of the fluid in the region of the channel channel provided with the protruding structure may be faster than the velocity of the fluid in the region of the channel channel where the protruding structure is not provided. Further, as described above, the velocity of the fluid in the region in the flow channel provided such that the protruding structure is symmetrical with respect to the two side faces of the flow channel is determined such that the protrusion- The velocity of the fluid in the region inside the flow channel can be made faster.

Such a phenomenon is caused by a venturi effect during movement of the fluid by the protrusion-type structure provided in the flow channel, thereby increasing the flowability of the fluid such as fuel, moisture, and the like in the flow channel.

5 and 6 schematically show a separator for a fuel cell according to an embodiment of the present application. More specifically, FIG. 5 schematically shows that a venturi effect is exhibited by providing a protruding structure on the inner surface of the flow channel. FIG. 6 shows the flow of fluid such as fuel, moisture, FIG. In FIG. 6, the flow rate of the fluid such as fuel, moisture, and the like is indicated by the arrow thickness, and the flow rate of the fluid is faster as the arrow is thicker.

In the present application, the specific form of the projection-like structure is not particularly limited. More specifically, the protrusion shape may be in the form of a triangle, a rectangle, a circle, an ellipse, a composite type in which they are connected to each other, a wavy shape, and the like, but is not limited thereto. In particular, it is preferable that the protruding structure has a circular or elliptical shape with an angle of 90 degrees or less between the inner surface of the channel channel and the outer surface of the protruding shape.

The total thickness of the protruding structure may be 1 to 50% of the thickness of the channel channel, but is not limited thereto.

The width of the channel channel may be 0.5 to 2 mm, and the depth of the channel channel may be 0.5 to 1.5 탆, but the present invention is not limited thereto.

In the present application, the fluid may be air, hydrogen, oxygen, methanol or water.

The protrusion-type structure may include the same material as the separator plate for the fuel cell, and the protrusion-type structure may be integrated with the separator plate for the fuel cell.

In the present application, the separator for fuel cells may be formed using materials and methods known in the art. More specifically, the separator for a fuel cell can be formed using black hues, a composite carbon-based material, a metal, and the like, but is not limited thereto.

The present application also provides a fuel cell including the separator for a fuel cell.

The fuel cell may be formed using materials and methods known in the art, except that the fuel cell includes a separation plate for a fuel cell as described above. More specifically, the fuel cell includes a fuel cell stack including a separator plate provided between at least one membrane electrode assembly and a membrane electrode assembly; A fuel supply unit for supplying fuel to the stack; And an oxidizing agent supply unit for supplying the oxidizing agent to the stack. However, the present invention is not limited thereto.

The membrane electrode assembly may include a polymer electrolyte membrane; And an anode electrode and a cathode electrode provided opposite to each other with the polymer electrolyte membrane interposed therebetween.

In the present application, an anode electrode, which is an electrode through which the anode fluid is supplied, is referred to as an oxidizing electrode or a fuel electrode, and a fuel is supplied from the anode electrode to generate hydrogen ions (H ⁺ ) and electrons . The cathode electrode, which is the electrode through which the cathode fluid is supplied, is referred to as a reducing electrode, an oxygen electrode, or an air electrode. At the cathode electrode, hydrogen ions and oxygen which have passed through the polymer electrolyte membrane are combined with each other to produce water by the reduction reaction of oxygen.

The anode electrode and / or the cathode electrode may have a structure in which at least one catalyst layer is independently formed on the gas diffusion layer.

In the present application, the catalyst contained in the catalyst layer may mean either a metal catalyst alone or a metal catalyst supported on a carbon-based support. The catalyst layer may be formed by a conventional method known in the art and may be formed, for example, by applying a catalyst ink containing a catalyst, an ionomer, and a solvent for promoting catalyst dispersion onto the gas diffusion layer and drying the same. At this time, a plurality of catalyst layers may be formed by sequentially coating and drying the catalyst ink having different ionomer contents. The catalyst ink may further include a proton conductive polymer.

As the metal catalyst, platinum, a transition metal or a platinum-transition metal alloy may be used as a typical example. Specifically, platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum- And platinum-rhodium alloy, but is not limited thereto.

Examples of the carbon-based support include graphite, carbon black, acetylene black, denka black, cacao black, activated carbon, mesoporous carbon, carbon nanotubes, carbon nanofibers, carbon nanofines, carbon nanorings, carbon nanowires, One or a mixture of two or more selected from the group consisting of fullerene (C60) and super P may be used.

The ionomer may serve to provide a path for ions generated by the reaction between the fuel and the catalyst, such as hydrogen or methanol, to move to the electrolyte membrane. The ionomer may specifically be a sulfonated polymer such as Nafion ionomer or sulfonated polytrifluorostyrene.

As the solvent for promoting the catalyst dispersion, one or a mixture of one or more selected from the group consisting of water, butanol, iso propanol (IPA), methanol, ethanol, n-propanol, n-butyl acetate and ethylene glycol is preferable Lt; / RTI > The same solvent may be used for the solvent for the anode and the solvent for the cathode.

The ratio of the solvent in the catalyst ink may be 100 to 5,000 parts by weight based on 100 parts by weight of the catalyst used. When the amount of the solvent used is 100 parts by weight or more, the viscosity of the catalyst ink is prevented from becoming too high, thereby preventing the degradation of the dispersibility of the catalyst particles during coating, and a uniform catalyst layer can be formed. If the amount is less than 5,000 parts by weight, the viscosity of the catalyst ink is prevented from becoming too low, and if the thickness of the catalyst layer coated at one time is thin, it is possible to prevent the problem that the coating is repeated several times, .

At this time, the method of applying the catalyst ink on the gas diffusion layer may include printing, tape casting, spraying, rolling, blade coating, die coating, spin coating, inkjet coating or brushing However, the present invention is not limited thereto.

The gas diffusion layer is not particularly limited as long as the substrate is generally conductive and has a porosity of 80% or more, and may include a conductive substrate selected from the group consisting of carbon paper, carbon cloth, and carbon felt. The thickness of the substrate may be 30 to 500 mu m. If the value is within the above range, the balance between the mechanical strength and the diffusion property of gas and water can be appropriately controlled. 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 carbon-based material and a fluororesin. The microporous layer promotes the discharge of excess water present in the catalyst layer, thereby suppressing the occurrence of flooding.

Examples of the carbon-based material include graphite, carbon black, acetylene black, denka black, cacao black, activated carbon, mesoporous carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, carbon nano ring, Fullerene (C60), and super P may be used, but are not limited thereto.

Examples of the fluororesin include polytetrafluoroethylene, polyvinylidene fluoride (PVdF), polyvinyl alcohol, cellulose acetate, copolymers of polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) and styrene-butadiene rubber (SBR) may be used, but the present invention is not limited thereto.

In the present application, the polymer electrolyte membrane may include those conventionally known in the art, if it is a polymer having hydrogen ion conductivity. The polymer having hydrogen ion conductivity may be a polymer having one or two or more cation-exchange groups selected from the group consisting of a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, and derivatives thereof in the side chain.

Specifically, the polymer electrolyte membrane may be formed of a perfluorosulfonic acid polymer, a hydrocarbon polymer, an aromatic sulfonic polymer, an aromatic ketone polymer, a polybenzimidazole polymer, a polystyrene polymer, a polyester polymer, a polyimide polymer, Based polymers, polyether sulfone-based polymers, polyphenylene sulfide-based polymers, polyphenylene oxide-based polymers, polyphosphazene-based polymers, polyethylene naphthalate-based polymers, polyester-based polymers, doped polybenzimidazole-based polymers And may include one or two or more polymers selected from the group consisting of polymers, polyether ketone-based polymers, polyphenylquinoxaline-based polymers, and polysulfone-based polymers. But are not limited to, a single copolymer, an alternating copolymer, a random copolymer, a block copolymer, a multi-block copolymer, or a graft copolymer of the polymer.

Recently, a sulfonated polymer has been attracting attention as a material of a non-fluorinated polymer electrolyte membrane. Examples thereof include sulfonated polyarylene ether-based polymers, sulfonated polyether ketone-based polymers, sulfonated polyetheretherketone-based polymers, sulfonated polyamide-based polymers, sulfonated polyimide-based polymers, sulfonated polyphosphazene- A polymer, a sulfonated polystyrene-based polymer, and a sulfonated low-density polyethylene-g-polystyrene-based polymer that is radiation-polymerized. But are not limited to, a single copolymer, an alternating copolymer, a random copolymer, a block copolymer, a multi-block copolymer, or a graft copolymer of the polymer.

The thickness of the polymer electrolyte membrane may be 5 to 100 탆, specifically 5 to 50 탆, more specifically 10 to 20 탆, but is not limited thereto. When the thickness of the polymer electrolyte membrane is 5 mu m or more, the polymer electrolyte membrane can have a desired level of mechanical strength. When the thickness of the polymer electrolyte membrane is 100 mu m or less, the hydrogen ion conductivity may be lowered.

In the present application, the membrane electrode assembly for fuel electrode may be manufactured by a conventional method known in the art, such that the catalyst layer of the anode electrode and the catalyst layer of the cathode electrode are in contact with the polymer electrolyte membrane. For example, the cathode electrode; An anode electrode; And a polymer electrolyte membrane positioned between the cathode and the anode in close contact with each other at a temperature of 100 ° C to 400 ° C.

In addition, after forming the anode electrode or the cathode electrode, the concavo-convex pattern may be further formed with an uneven pattern on the anode electrode or the cathode electrode using the same material.

The stack for a fuel cell can generate electricity through an electrochemical reaction between a fuel and an oxidant.

The fuel supply unit supplies the fuel to the electricity generation unit, and may include a fuel tank for storing the fuel and a pump for supplying the fuel stored in the fuel tank to the electricity generation unit. The fuel may be selected from the group consisting of methanol, ethanol, butanol, propanol, formic acid, aqueous hydrogen compound solution and hydrogen gas. More specifically, it may be a hydrogen gas.

The oxidant supply part serves to supply the oxidant to the electricity generation part. The oxidizing agent may be oxygen or air, and oxygen or air may be injected by pumping.

The separator for a fuel cell according to an embodiment of the present application can have a venturi effect of a fluid by including a protruding structure in at least a part of the inner surface of the channel channel to thereby exhibit a fluid effect such as fuel, It is possible to increase the flowability of the fluid.

In addition, the separation plate according to one embodiment of the present application can prevent the phenomenon of stagnation of fluid such as fuel, moisture and the like, thereby improving the performance of the fuel cell.

Claims (11)

Wherein a channel channel for fluid movement is provided on at least one surface in a concave shape,
Wherein at least a part of the inner surface of the channel channel is provided with a protruding structure,
Wherein the inner surface of the channel channel includes a region in the channel channel provided with the protruding structure and a region in the channel channel in which the protruded structure is not provided,
Wherein the inner surface of the flow channel has a bottom surface and two opposite side surfaces,
Wherein the protruding structure is symmetrical with respect to two side surfaces of the flow channel,
The protruding structure is further provided on a bottom surface of the flow channel,
The thickness of the protruding structure provided on the side surface of the channel channel is 1% or more and 50% or less of the thickness of the channel channel,
The protruding structure has a circular or elliptical shape with an angle of 90 degrees or less between the inner surface of the channel channel and the outer surface of the protruding shape,
Wherein the velocity of the fluid in the region of the flow channel provided with the projection-like structure is higher than the velocity of the fluid in the region of the flow channel where the projection-like structure is not provided. delete delete delete delete delete The fuel cell system according to claim 1, wherein the protruding structure includes the same material as the separator plate for the fuel cell,
And the protruding structure is integrated with the separator for fuel cells. The separator for a fuel cell according to claim 1, wherein the width of the flow channel is 0.5 to 2 mm. The separator for a fuel cell according to claim 1, wherein a depth of the flow channel is 0.5 to 1.5 占 퐉. The separator for a fuel cell according to claim 1, wherein the fluid is air, hydrogen, oxygen, methanol or water. A fuel cell comprising the separator plate for a fuel cell according to any one of claims 1 to 7.

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