KR101009621B1 - Stack for fuel cell and fuel cell system having the same - Google Patents

Abstract

The present invention has a membrane-electrode assembly (Membrane-Electrode assembly), the channel and the movement of hydrogen and oxygen so that the adhesion between the separator and the membrane-electrode assembly without the use of a separate adhesive on both sides of the membrane-electrode assembly Provided is a fuel cell stack including a separator disposed in close contact with each other and a heating unit installed along an outer circumference of the separator in contact with the membrane-electrode assembly to apply heat to the membrane-electrode assembly.

Fuel Cell, Stack, Separator, Hot Wire, Groove, Cover

Description

Stack for fuel cell and fuel cell system having same {STACK FOR FUEL CELL AND FUEL CELL SYSTEM HAVING THE SAME}

1 is a block diagram schematically showing the overall configuration of a fuel cell system according to an embodiment of the present invention.

2 is an exploded perspective view illustrating an electricity generating unit of a stack for a fuel cell according to an exemplary embodiment of the present invention.

3 is a cross-sectional view of the coupling cross-sectional view of FIG. 2 according to an embodiment of the present invention.

4 to 6 are cross-sectional views illustrating some components of an electricity generating unit according to still another exemplary embodiment of the present invention.

The present invention relates to a fuel cell system. More particularly, the present invention relates to separators in stacks used in fuel cell systems.

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

This fuel cell is classified into a phosphoric acid fuel cell, a molten carbonate fuel cell, a solid oxide fuel cell, a polymer electrolyte type or an alkaline fuel cell according to the type of electrolyte used. Each of these fuel cells operates on essentially the same principle, but differs in the type of fuel used, operating temperature, catalyst, and electrolyte.

Among these, the polymer electrolyte fuel cell (PEMFC, hereinafter referred to as PEMFC for convenience), which has been developed recently, has excellent output characteristics, low operating temperature, and fast start-up and response characteristics compared to other fuel cells. In addition to mobile power supplies such as automobiles, as well as distributed power supplies such as homes and public buildings and small power supplies such as for electronic devices has a wide range of applications.

Such a PEMFC basically includes a stack, a reformer, a fuel tank, a fuel pump, and the like to constitute a system. The stack forms the body of the fuel cell, and the fuel pump supplies the fuel in the fuel tank to the reformer. The reformer reforms the fuel to generate hydrogen gas and supplies the hydrogen gas to the stack. Thus, the PEMFC supplies fuel in the fuel tank to the reformer by operation of the fuel pump, reforming the fuel in the reformer to generate hydrogen gas, and electrochemically reacting the hydrogen gas and oxygen in the stack to generate electrical energy. Let's do it.

In the fuel cell as described above, the stack that substantially generates electricity is a stack of several to tens of cells of a unit consisting of a membrane-electrode assembly and a separator called bipolar plates in the art. Made of structure.

In this case, in order to form a stack by stacking the separator and the membrane-electrode assembly, the fuel and the like supplied through the separator are sealed between the two members to prevent leakage of the fuel through the gap between the separator and the membrane-electrode assembly.

Conventionally, in order to seal between the separator and the membrane-electrode assembly, after sealing using a sealant, the stack is pressurized, and thus there is a problem in that the manufacturing process is complicated and workability is inferior.

In other words, the sealant sealing between the separator and the membrane-electrode assembly requires a curing time including most of the polymer resin and additives. As a result, when the stack is constructed, workability is deteriorated and time waste due to the curing time of the sealing agent is inevitable.

The present invention has been made in view of the above problems, and an object thereof is to provide a fuel cell stack and a fuel cell system having the same, in which a separator and a membrane-electrode assembly can be adhered to each other without using an adhesive. have.

In addition, another object of the present invention is to provide a fuel cell stack and a fuel cell system having the same, wherein the separator and the membrane-electrode assembly are easily adhered to improve workability.

In addition, another object of the present invention is to provide a fuel cell stack and a fuel cell system having the same, which can shorten the stack manufacturing time and increase productivity.

In order to achieve the above object, a stack for a fuel cell according to the present invention includes a membrane-electrode assembly and a separator disposed closely on both sides of the membrane-electrode assembly while having a moving channel of hydrogen and oxygen. Separator),

The separator may include a heating unit installed along an outer circumference of the membrane-electrode assembly and applying heat to the membrane-electrode assembly.

In the stack for a fuel cell according to the present invention, each separator may be in close contact with the membrane-electrode assembly to form a hydrogen passage and an oxygen passage by the channel.

In addition, the fuel cell stack according to the present invention includes at least one electricity generating unit by the membrane-electrode assembly and the separator.

The heat generated by the heating unit is preferably such that the film-electrode assembly can be melted.

Accordingly, even when a separate adhesive is not used, the membrane-electrode assembly may be adhered to the separator in contact with the melted electrode by the heat generated from the heating unit.

In addition, the separator may be continuously formed so that the heating unit is installed along the outer circumference.

In addition, the installation position of the heating unit is preferably an inactive region of the membrane-electrode assembly.

The heating unit may be a heating wire heated by electricity.

In addition, the hot wire may protrude outward with respect to the front surface of the separator in contact with the membrane-electrode assembly.

In addition, the hot wire may be formed in a circular cross-sectional structure, such as a flat rectangular cross-sectional structure is not particularly limited in its structure.

The separator may have a structure in which a hot wire is inserted into a groove formed in the separator and a cover covers the groove to the outside thereof.

In this case, the cover is preferably made of the same material as the separator.

In addition, the heating wire may have a structure in which a coating material is wrapped on an outer circumferential surface, and the coating material may be the same material as the separator.

In addition, the fuel cell system according to the present invention for achieving the above object, at least one of the electricity generating unit for generating electrical energy by the reaction of the fuel and oxygen, a fuel supply source for supplying fuel to the electricity generating unit; An oxygen supply source for supplying oxygen to the electricity generating unit,

The electricity generating unit includes a membrane-electrode assembly and a separator disposed on both sides of the membrane-electrode assembly.

The separator may be provided with a heating unit for applying heat to the membrane-electrode assembly along an outer circumference of the membrane-electrode assembly.

In the fuel cell system according to the present invention, hydrogen gas may be used as the fuel, and a fuel composed of a liquid phase may be used.

Further, the fuel cell system according to the present invention has a structure in which the oxygen can be obtained through air.

And the fuel cell system which concerns on this invention is provided with the said electric generator part in plurality, and can form the stack by the aggregate structure of these electric generator parts.

The fuel cell system according to the present invention configured as described above may be configured by a polymer electrolyte fuel cell (PEMFC) method, and configured by a direct methanol fuel cell (DMFC) method. May be

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

1 is a block diagram schematically showing the overall configuration of a fuel cell system according to an embodiment of the present invention.

The fuel cell system 100 according to the present invention will be described with reference to the drawings. The fuel cell system 100 reforms a hydrocarbon-based fuel to generate hydrogen gas, and generates the hydrogen gas and the oxidant gas. A polymer electrolyte fuel cell (PEMFC) method that chemically reacts to generate electrical energy is employed.

In the fuel cell system 100, the fuel for generating electricity includes a fuel made in a liquid or gaseous state such as methanol, ethanol, or natural gas. However, the fuel described in this embodiment means a fuel made of a liquid phase for convenience.

The system 100 may use oxygen gas stored in a separate storage means as an oxidant gas that reacts with hydrogen gas, and may use air containing oxygen. However, the latter example is explained below.

The fuel cell system 100 according to the present invention basically includes a stack 10 for generating electrical energy through a reaction between hydrogen and oxygen, and a stack 10 for generating hydrogen gas from the fuel described above. ) And a fuel supply source 30 for supplying air) and an oxygen supply source 50 for supplying air to the stack 10.

In the above, the stack 10 is supplied with hydrogen gas from the reformer 35 as mentioned above, and is supplied with air from the oxygen source 50 to provide electricity through oxidation / reduction reaction of the hydrogen gas and oxygen contained in the air. At least one electricity generating unit 11 for generating energy is provided. This stack 10 will be described in more detail later with reference to 2.

The fuel supply source 30 includes a fuel tank 31 for storing the above-described fuel, a fuel pump 33 connected to the fuel tank 31 to discharge the fuel, a fuel tank 33 and a stack ( And a reformer 35 disposed between 10) to receive fuel from the fuel tank 33 to generate hydrogen gas from the fuel, and to supply the hydrogen gas to the electricity generator 11.

In the fuel source 30, the reformer 35 preferably generates hydrogen gas from the fuel through a catalytic reaction such as steam reforming, partial reforming or autothermal reaction with thermal energy. In addition, the reformer 35 may reduce the concentration of the carbon monoxide by, for example, a catalytic reaction such as a water gas conversion method, a selective oxidation method, or purification of hydrogen using a separator. Since the reformer 35 may be formed of a conventional PEMFC reformer configuration, detailed description thereof will be omitted herein.

The oxygen source 50 includes an air pump 51 capable of sucking air and supplying the air to the electricity generator 11.

Therefore, upon operation of the fuel cell system 100 according to the present invention, hydrogen gas is supplied to the electricity generating unit 11 of the stack 10 through the fuel supply source 30, and air is supplied through the oxygen supply source 50. When supplied to the electricity generator 11, the electricity generator 11 generates electrical energy, water, and heat through an electrochemical reaction between hydrogen in hydrogen gas and oxygen contained in air.

As an alternative, the fuel cell system 100 according to the present invention is a direct methanol for supplying a liquid fuel such as methanol and ethanol directly to the electric generator 11 to generate electrical energy through an electrochemical reaction of hydrogen and oxygen. DMFC (Direct Methanol Fuel Cell) method may be employed. Unlike the polymer electrolyte fuel cell system, the fuel cell system 100 of the direct methanol fuel cell system does not require the reformer 35 shown in FIG. 1, and the fuel tank 31 and the fuel pump 33 are not limited to the fuel cell system 100. It may include a fuel supply (30) consisting of.

In the fuel cell system 100 according to the present invention configured as described above, embodiments of the stack 10 described above will be described in detail with reference to the accompanying drawings.

2 is an exploded perspective view illustrating an electricity generating unit of a stack for a fuel cell according to an exemplary embodiment of the present invention, and FIG.

Referring to the drawings, the fuel cell stack 10 according to the present embodiment is formed as an aggregate structure by these electricity generating units 11 by arranging the plurality of electricity generating units 11 mentioned above in succession.

The electricity generator 11 is a membrane electrode assembly (MEA) (hereinafter referred to as "MEA") (12) centered on both sides of the separator (Separator) (in the art 'bipolar plate) 13 and 15 are closely arranged to constitute a fuel cell of a minimum unit for generating electricity.

MEA (12) is made of a polymer Nephion and has an active region (12a) having a predetermined area and the oxidation / reduction reaction occurs, the anode electrode on one side of the active region 12a, the cathode electrode on the other side And an electrolyte membrane provided between the two electrodes. In addition, the edge portion of the active region 12a is connected to the gasket portion 12b, which is an inactive region which is not related to the oxidation / reduction reaction, and the gasket portion 12b is melted by the heating portion of the separator described later. As a result, the edges of the active region 12a are sealed between the separators 13 and 15.

The anode electrode of the MEA 12 serves to convert hydrogen into hydrogen ions (protons) and electrons by oxidizing the hydrogen gas supplied from the reformer 35 (FIG. 1). The cathode electrode of the MEA 12 has a function of reducing and reacting oxygen in the air supplied from the air pump 51 (FIG. 1) with hydrogen ions transferred from the anode electrode to generate heat and moisture at a predetermined temperature. The electrolyte membrane of the MEA 12 functions as an ion exchange to move hydrogen ions generated at the anode electrode to the cathode electrode.

On the other hand, according to the present embodiment, the separators 13 and 15 are closely disposed on both surfaces thereof with the MEA 12 interposed therebetween, and the hydrogen passages by the hydrogen and oxygen transfer channels 13c and 15c described later on the surface thereof. 14 and an oxygen passage 17, and a hydrogen manifold 16 and an oxygen manifold 19 for supplying hydrogen and oxygen to the passages 14 and 17 are formed through.

In this case, the hydrogen passage 14 is positioned at the anode electrode of the MEA 12 to supply hydrogen gas supplied from the reformer 35 (FIG. 1) to the anode electrode. The oxygen passage 17 is positioned at the cathode electrode of the MEA 12 to supply air supplied from the air pump 51 (FIG. 1) to the cathode electrode.

In addition, each of the separators 13 and 15 is provided with a groove 41 in the form of a channel continuously along the contact edge corresponding to the gasket portion 12b of the MEA, and heat is generated in accordance with the current supply in the groove 41. It is a structure provided with the heating wire 40 which generate | occur | produces.

In the present embodiment, the heating wire 40 has a circular cross-sectional structure and the groove 41 has a semi-circular cross-sectional structure. When the heating wire 40 is inserted into the groove 41, the heating wire 40 is a separator 13, 15. ) To protrude outward from the front of the.

In addition, the grooves 41 are continuously formed along the edges of the separators 13 and 15, and each end thereof extends to the hydrogen manifold 16 or the oxygen manifold 19 formed in the separators 13 and 15. It communicates with the minority manifold 16 or the oxygen manifold 19.

The hot wire 40 is placed along the groove 41 and both ends thereof extend to the hydrogen manifold 16 or the oxygen manifold 19 communicating with the groove 41 to finally fall out of the stack 10. Come out.

Accordingly, the current can be easily applied to both ends of the heating wire 40 from the outside of the stack 10.

In this embodiment, the withdrawal position of the heating wire 40 is set to a hydrogen manifold or an oxygen manifold, but is not necessarily limited thereto and may be variously modified according to the structure of the stack.

3 illustrates the state in which the separator is in close contact with both sides of the MEA with the MEA interposed therebetween.

According to the above-described drawings, the separators 13 and 15 are arranged in close contact with both sides of the MEA 12 and constitute the minimum generation of the electricity generating unit 11, so that the moving channels 13c and 15c are provided. The ribs between the moving channels 13c and 15c are spaced on both sides of the MEA 12, and the ribs close to the both sides of the MEA 12 to form the hydrogen passage 14 and the oxygen passage 17 as mentioned.

As a result, the hydrogen gas supplied from the reformer 35 and the air supplied by the air pump 51 flow along the hydrogen passage 14 and the oxygen passage 17 under a predetermined pressure.

As mentioned above, the hot wire 40 inserted into the grooves 41 of the separators 13 and 15 presses the gasket portion 12b of the MEA 12 while protruding from the front surface of the separators 13 and 15. It comes in close contact with the gasket portion 12b.

When a current is applied to the heating wire 40 in this state, the heating wire 40 is heated while the gasket portion 12b of the MEA 12 in close contact with the heating wire is melted by the high heat generated from the heating wire, so that the separator 13, 15) is bonded.

The gasket portion 12b of the MEA 12 is made of a polymer which is melted when the material is applied to the separator so that the gasket portion 12b may be melt-attached to the separators 13 and 15 by the high heat applied by the heating wire 40 as described above. .

Here, as shown in FIG. 4, the grooves 41 formed in the separators 13 and 15 are formed to have a depth corresponding to the diameter of the heating wire 40 so that the heating wire 40 does not protrude out of the separator. It may not be a structure.

5 and 6 show other embodiments of the present separator.

That is, as shown in FIG. 5, the separators 13 and 15 have grooves 41 formed along edges thereof, and the heating wire 40 inserted into the grooves 41 has the separators 13 and 15 formed on an outer circumferential surface thereof. The coating layer 42 made of the same material is coated.

Accordingly, the separators 13 and 15 have a structure in which the heating wire 40 having the coating layer 42 coated thereon is inserted into the groove 41 so that the heating wire 40 is not exposed to the outside.

In the separators 13 and 15 according to the embodiment of FIG. 6, a rectangular groove 41 is formed along an edge thereof, and a hot wire 40 having a rectangular cross-sectional shape is inserted into the groove 41, and the outer side of the separator 13 and 15 is inserted into the separator 41. The cover plate 43 covering the groove 41 is provided so that the heating wire 40 is not exposed to the outside.

Here, the outer surface of the cover plate 43 has a height corresponding to the outer surface of the separator (13, 15) so that the outer surface of the separator (13, 15) and the cover plate 43 can be placed on the same plane, The cover plate 43 is made of the same material as the separators 13 and 15.

In the structure described above, the coating layer 42 or the cover plate 43 made of the same material as the separators 13 and 15 is positioned between the hot wire 40 and the MEA 12 in close contact with the separators 13 and 15. The gasket portion 12b of 12 is substantially prevented from coming into contact with the heating wire 40, and the gasket portion 12b has only a coating layer 42 made of the same material as the separators 13 and 15 or the separators 13 and 15. ) Or only the cover plate 43.

Accordingly, when a current is applied to the heating wire 40 so that the heating wire 40 is heated, the high heat generated by the heating wire 40 is transferred to the MEA 12 through the coating layer 42 or the cover plate 43 to the MEA 12. The gasket portion 12b is melted, and the molten gasket portion 12b is formed of the coating layer 42 and the cover plate made of the same material as the separators 13 and 15, not the heating wire 40, even at the position where the grooves 41 are formed. 43), it is possible to increase the adhesion.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the scope of the invention.

According to the present invention as described above, by melting and attaching the MEA to the separator by heat, it is possible to reduce the cost increase due to the use of a separate sealing agent.

In addition, the adhesion between the separator and the MEA is easy, thereby improving workability.

In addition, by shortening the adhesion process and the adhesion time between the MEA and the separator can reduce the manufacturing time of the stack, thereby increasing the productivity.

Claims (19)

delete Membrane-electrode assembly; A separator disposed in close contact with both surfaces of the membrane-electrode assembly while having a moving channel of hydrogen and oxygen; A heating unit installed along an outer circumference of the separator in contact with the membrane-electrode assembly to apply heat to the membrane-electrode assembly; Including, The heating unit includes a heating wire heated by electricity, the separator is continuously formed with a groove into which the heating wire is inserted, And a gasket portion located at an edge of the membrane electrode assembly, wherein the gasket portion is melted and adhered to the separator. delete delete delete delete delete delete delete delete delete delete delete At least one electricity generating portion for generating electrical energy by reaction of fuel and oxygen; A fuel supply source for supplying fuel to the electricity generator; And An oxygen supply source for supplying oxygen to the electricity generating unit, The electricity generating unit includes a membrane-electrode assembly and a separator disposed on both sides of the membrane-electrode assembly. The separator is provided with a heating unit for applying heat to the membrane-electrode assembly along the outer circumferential portion in contact with the membrane-electrode assembly, The heating unit includes a heating wire heated by electricity, the separator is continuously formed with a groove into which the heating wire is inserted, And a gasket portion located at an edge of the membrane electrode assembly, wherein the gasket portion is melted and adhered to the separator. delete delete delete delete delete

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