FUEL CELL AND FUEL CELL STACK

Description

Technical Field

[0001] The present invention relates to a fuel cell and a fuel cell stack comprising the same.Background Art

[0002] Generally, a fuel cell is an energy conversion device that generates electric energy through an electrochemical reaction between an oxidant (fuel) and a reducing agent, which has an advantage that power can be continuously generated as long as the fuel is continuously supplied.

[0003] Figures 1 and 2 are schematic diagrams showing a conventional fuel cell stack (1).

[0004] The fuel cell stack (1) comprises a plurality of fuel cells (10), and the plurality of fuel cells is laminated to form a stack.

[0005] The fuel cell stack (1) may comprise a membrane-electrode assembly (MEA) (11) equipped with an electrode layer formed by coating an anode (11a) and a cathode (11b) around an electrolyte membrane composed of a polymer material, respectively, a thermal pressure-sensitive adhesive protective film (17) (sub-gasket) of a plastic film material on the outer circumference of the electrode layer region, a gas diffusion layer (12) (GDL) functioning to distribute reactive gases evenly throughout a reaction zone and to transfer electrons generated by oxidation reaction of the anode electrode toward the cathode electrode, a separating plate (13) (bipolar plate) of graphite and metal materials for supplying reactive gases to the gas diffusion layer and having the same function, and a gasket (18) of an elastic rubber material disposed on the outer periphery of the reaction zone of the separating plate or the membrane-electrode assembly to prevent leakage of reactive gases and cooling water.

[0006] The separating plate (13) comprises a plurality of ribs (14) in contact with the gas diffusion layer (12) and a plurality of channels (15) for guiding the flow of the reaction gas. Also, the separating plate (13) has a cooling water channel (16) for guiding the flow of the cooling water therein.

[0007] Furthermore, the ion moving direction is formed along the membrane thickness direction (F).

[0008] In particular, the polymer electrolyte fuel cell requires humidification of the fuel in order to secure ionic conductivity of the polymer electrolyte. Specifically, a hydrogen fuel cell is a device converting into electric energy through a redox reaction of hydrogen gas and oxygen (air) gas, and for ion conduction, water (humidification) is required for a catalyst layer, which is a reaction surface, and the electrolyte membrane, which is a medium of ion conduction, for electrochemical reactions.

[0009] For this reason, humidification is required for the reaction of hydrogen and air as reactants, and fuel cell technology driven by low humidification or no humidification is required for humidifier capacity reduction and system cost reduction. Accordingly, techniques for various self-humidifying methods for securing a humidification amount in a low humidification environment have been developed.

[0010] JP 2014 192 095 A relates to a membrane electrode assembly and solid polymer fuel cell. A membrane electrode assembly includes an electrolyte layer, a fuel electrode catalyst layer in contact with the electrolyte layer, and an air electrode catalyst layer in contact with the electrolyte layer. The fuel electrode catalyst layer and the air electrode catalyst layer are arranged on the same side with respect to the electrolyte layer in the thickness direction of the electrolyte layer. The electrolyte layer has a flat surface, and the fuel electrode catalyst layer and the air electrode catalyst layer are arranged on the flat surface.

[0011] US 2005 112 433 A1 relates to micro-machined fuel cells. One embodiment varies the thickness of the electrolyte and positions at least either the anode or cathode in the recessed region to provide a short travel distance for ions traveling from the anode to the cathode or from the cathode to the anode. A second embodiment uses a manifold cover configured to allow close positioning of the anode to the cathode.Disclosure Technical Problem

[0012] It is an object of the present invention to provide a fuel cell stack which is driven at low humidification or no humidification of a reactive fuel.Technical Solution

[0013] To solve the above object, according to one aspect of the present invention, there is provided a fuel cell comprising a membrane-electrode assembly having a first surface and a second surface opposite to the first surface, wherein an anode electrode and a cathode electrode are each disposed on the first surface; an end plate disposed apart at a predetermined interval on the second surface; a first gas diffusion layer disposed on the anode electrode; a second gas diffusion layer disposed on the cathode electrode; a first separating plate disposed on the first gas diffusion layer and having a plurality of flow channels; and a second separating plate disposed on the second gas diffusion layer and having a plurality of flow channels. A predetermined space portion is formed between the end plate and the second surface of the membrane-electrode assembly by a gasket for preventing leakage of cooling water, where the second surface of the membrane-electrode assembly is exposed to the space portion. Cooling water is supplied to the space portion between the end plate and the second surface of the membrane-electrode assembly.Advantageous Effects

[0014] As described above, the fuel cell stack related to one example of the present invention has the following effects.

[0015] It can be operated in low humidification or no humidification, and it is possible to use non-humidifying reactants (hydrogen, oxygen (air)) when driving the fuel cell.

[0016] Particularly, it has a structure in which the reactant is injected in a non-humidified state (dray gas) and the cooling water, which is essentially supplied and operated to the fuel cell stack, can be used for humidifying the membrane-electrode assembly (MEA).

[0017] At this time, the reactant is supplied in a non-humidified state, but since one side of the membrane-electrode assembly is exposed to the cooling water, the membrane-electrode assembly can be humidified without the aid of the reactant as in the prior art.

[0018] Conventionally, gas permeation has been made along the thin thickness direction of the membrane, thereby affecting durability, but in the case of the present invention, the gas permeation is made along the surface direction of the membrane, thereby increasing the distance and the resistance, and improving OCV and durability by gas permeability reduction.Brief Description of Drawings

[0019] Figures 1 and 2 are schematic diagrams showing a fuel cell stack related to one example of the present invention. Figure 3 is a schematic diagram showing a fuel cell stack related to one example of the present invention. Figure 4 is a view showing the membrane-electrode assembly shown in Figure 3. Figure 5 is an exploded perspective view of a fuel cell related to one example of the present invention. Figure 6 is a schematic diagram showing various examples of a membrane-electrode assembly. Mode for Invention

[0020] Hereinafter, a fuel cell according to one example of the present invention and a fuel cell stack comprising the same will be described in detail with reference to the accompanying drawings.

[0021] In addition, the same or similar reference numerals are given to the same or corresponding components regardless of reference numerals, of which redundant explanations will be omitted, and for convenience of explanation, the size and shape of each constituent member as shown may be exaggerated or reduced.

[0022] Figure 3 is a schematic diagram showing a fuel cell stack (100) related to one example of the present invention, Figure 4 is a view showing the membrane-electrode assembly (210) shown in Figure 3, and Figure 5 is an exploded perspective view of a fuel cell (200) related to one example of the present invention.

[0023] In addition, Figure 6 is a schematic diagram showing various examples of a membrane-electrode assembly.

[0024] Referring to Figures 3 to 5, the fuel cell stack (100) comprises a plurality of fuel cells (200).

[0025] The fuel cell (200) comprises a membrane-electrode assembly (210), an end plate (240), a first gas diffusion layer (221), a second gas diffusion layer (222), a first separating plate (231) and a second separating plate (232).

[0026] According to the present invention, the fuel cell (200) comprises a membrane-electrode assembly (210) having a first surface and a second surface opposite to the first surface, wherein an anode electrode (211) and a cathode electrode (212) are each disposed on the first surface. Also, the fuel cell (200) comprises an end plate (240) that is disposed apart at a predetermined interval on the second surface of the membrane-electrode assembly (210). A predetermined space portion (S) is formed between the end plate (240) and the second surface of the membrane-electrode assembly (210) by a gasket (260) for preventing leakage of the cooling water, where the second surface of the membrane-electrode assembly (210) is exposed to the space portion (S).

[0027] In addition, the fuel cell (200) comprises a first gas diffusion layer (221) disposed on the anode electrode (211) and a second gas diffusion layer (222) disposed on the cathode electrode (212). That is, both the first gas diffusion layer (221) and the second gas diffusion layer (222) are disposed on the first surface of the membrane-electrode assembly (210).

[0028] Furthermore, the fuel cell (200) comprises a first separating plate (231) disposed on the first gas diffusion layer (221) and having a plurality of flow channels, and a second separating plate (232) disposed on the second gas diffusion layer (222) and having a plurality of flow channels. The first and second separating plates (231, 232) have a plurality of ribs in contact with the respective gas diffusion layers and a plurality of flow channels through which the reaction gas flows. Also, the first and second separating plates (231, 232) may have cooling water channels for guiding the flow of the cooling water therein.

[0029] In this structure, the ion moving direction is the plane direction (F) of the membrane-electrode assembly (210).

[0030] In addition, the cooling water can be supplied into the space between the end plate (240) and the second surface of the membrane-electrode assembly (210). Accordingly, the second surface of the membrane-electrode assembly (210) is exposed to the cooling water and humidified. Furthermore, the end plate (240) of any one fuel cell (200) is in contact with the first and second separating plates of another fuel cell which is adjacently laminated. At this time, the first and second separating plates of the adjacent fuel cell are cooled via the end plate (240).

[0031] That is, by supplying the cooling water to the space between the second surface of the membrane-electrode assembly (210) and the end plate (240), the cooling of the fuel cell (200) and the humidification of the membrane-electrode assembly can be performed simultaneously.

[0032] Also, a channel member for guiding the flow of the cooling water may be disposed in the space between the end plate (240) and the second surface of the membrane-electrode assembly (210). At this time, the channel member may comprise a mesh member (250). In addition, the channel member may comprise a channel and a porous mesh member.

[0033] Furthermore, the fuel cell (200) may comprise at least one first gasket (270) for individually sealing the first gas diffusion layer (221) and the second gas diffusion layer (222). For example, in order to individually seal the first gas diffusion layer (221) and the second gas diffusion layer (222), the first gasket (270) may comprise a first opening (271) in which the first gas diffusion layer (221) is accommodated, and a second opening (272) in which the second gas diffusion layer (222) is accommodated.

[0034] The first separating plate (231) and the second separating plate (232) have electrical conductivity, and in order to electrically insulate the first separating plate (231) and the second separating plate (232), the fuel cell (200) may further comprise an insulating member (280) disposed between the first separating plate (231) and the second separating plate (232). The insulating member (280) may comprise a plastic material such as acrylic, polycarbonate, Teflon and polyvinyl chloride, and the insulating member (280) may also be integrally formed of the same material as the end plate (240).

[0035] According to the present invention, the fuel cell (200) comprises a gasket(260) (also called second gasket) disposed between the end plate (240) and the second surface of the membrane-electrode assembly (210). The second gasket (260) may have an opening in the central region, and the above-described mesh member (250) may be inserted into the opening.

[0036] In addition, the end plate (240) is an insulating end plate, which may have electrical insulation. The end plate (240) may be formed of an electrically insulating material. For example, the end plate (240) may be formed of a plastic material such as acrylic, polycarbonate, Teflon and polyvinyl chloride, and the end plate (240) may be formed of the same material as the insulating member (280) and may also be integrally formed with the insulating member (280).

[0037] Referring to Figure 6, in the membrane electrode assemblies (210, 210', 210"), the anode electrodes (211, 211', 211") and the cathode electrodes (221, 221', 221") may have various shapes and sizes.Industrial Applicability

[0038] The fuel cell stack related to one example of the present invention can be driven at low humidification or no humidification and has a structure capable of using non-humidifying reactants (hydrogen, oxygen (air)) when driving the fuel cell.

Claims

1. A fuel cell (200) comprising: a membrane-electrode assembly (210) having a first surface and a second surface opposite to the first surface, wherein an anode electrode (211) and a cathode electrode (212) are each disposed on the first surface; an end plate (240) disposed apart at a predetermined interval on the second surface; a first gas diffusion layer (221) disposed on the anode electrode (211); a second gas diffusion layer (222) disposed on the cathode electrode (212); a first separating plate (231) disposed on the first gas diffusion layer (221) and having a plurality of flow channels; and a second separating plate (232) disposed on the second gas diffusion layer (222) and having a plurality of flow channels, wherein a predetermined space portion (S) is formed between the end plate (240) and the second surface of the membrane-electrode assembly (210) by a gasket (260) for preventing leakage of cooling water, where the second surface of the membrane-electrode assembly (210) is exposed to the space portion (S), and wherein cooling water is supplied to the space portion (S) between the end plate (240) and the second surface of the membrane-electrode assembly (210).

2. The fuel cell (200) according to claim 1, wherein a channel member (250) for guiding flow of the cooling water is disposed in the space portion (S) between the end plate (240) and the second surface of the membrane-electrode assembly (210).

3. The fuel cell (200) according to claim 2, wherein the channel member comprises a mesh member (250).

4. The fuel cell (200) according to claim 1, comprising at least one first gasket (270) for individually sealing the first gas diffusion layer (221) and the second gas diffusion layer (222).

5. The fuel cell (200) according to claim 1, comprising a first gasket (270) including a first opening (271) in which the first gas diffusion layer (221) is accommodated and a second opening (272) in which the second gas diffusion layer (222) is accommodated.

6. The fuel cell (200) according to claim 1, further comprising an insulating member (280) disposed between the first separating plate (231) and the second separating plate (232).

7. The fuel cell (200) according to claim 1, wherein the end plate (240) has electrical insulation.

8. A fuel cell stack (100) comprising the fuel cell (200) according to claim 1.