CN214254475U

CN214254475U - Fuel cell and repeating component for fuel cell

Info

Publication number: CN214254475U
Application number: CN202022762727.7U
Authority: CN
Inventors: 方谋; 许艳芳; 孙敏敏; 方达杰; 谭雨馨
Original assignee: Beijing Shuojing New Energy Technology Co ltd
Current assignee: Beijing Shuojing New Energy Technology Co ltd
Priority date: 2020-11-25
Filing date: 2020-11-25
Publication date: 2021-09-21
Anticipated expiration: 2030-11-25

Abstract

The application discloses a fuel cell and a repeating component for the fuel cell. The repeating unit includes: a plurality of bipolar plates including an anode plate, a cathode plate, and a common plate between the anode plate and the cathode plate; a first membrane electrode assembly positioned between the anode plate and the common plate; and a second membrane electrode assembly positioned between the cathode plate and the common plate, wherein each of the first membrane electrode assembly and the second membrane electrode assembly comprises a frame and a multi-layer membrane stack, the frame supporting the multi-layer membrane stack and being in sealing contact with the plurality of bipolar plates. The repeating unit not only reduces the number of bipolar plates using a common plate, but also improves the sealing performance of the bipolar plates using a frame in the membrane electrode assembly.

Description

Fuel cell and repeating component for fuel cell

Technical Field

The present invention relates to fuel cells, and more particularly, to repeating components for fuel cells.

Background

A fuel cell is a power generation device that obtains electrical energy by electrochemically reacting a fuel such as methanol or hydrogen with an oxidizing gas in a catalyst layer of a membrane electrode assembly. A plurality of repeating units including an electrolyte membrane and catalyst layers, diffusion layers, and bipolar plates on both side surfaces of the electrolyte membrane may be stacked in the fuel cell. The plurality of repeating parts are connected together to provide a rated power, not only can the area specific power of the fuel cell be increased, but also the miniaturization of the fuel cell can be facilitated.

During operation of the fuel cell, fuel fluid is transferred to the surface of the membrane electrode assembly through the flow channels of the anode flow field of the bipolar plate, and the transfer process inside the membrane electrode assembly is that the fuel fluid diffuses to the anode catalyst layer through the diffusion layer and emits electrons to form positive ions under the action of the catalyst layer. The electrons are transferred from the surface of the catalyst to the bipolar plate through the diffusion layer, then transferred from the bipolar plate to an external circuit, then transferred from the external circuit to the cathode bipolar plate, transferred from the cathode bipolar plate to the diffusion layer, and transferred from the diffusion layer to the cathode catalyst layer; the cations are transferred to the cathode side catalyst layer via the electrolyte membrane. The oxidizing gas combines with the electrons transferred from the anode on the cathode catalyst layer to form anions, and the anions combine with the cations transferred through the electrolyte membrane to form water, thereby forming a complete electronic circuit and an ionic circuit. The electrolyte membrane serves both as an ion channel and a barrier to gas and electrons.

In existing fuel cells, the repeating components include two or three bipolar plates. In the repeating unit of the two bipolar plates, an electrolyte membrane is sandwiched between an anode plate and a cathode plate, thereby forming a single cell unit in the stacking direction. In a repeating assembly of three bipolar plates, an anode plate, a common plate and a cathode plate are stacked in sequence, the common plate comprising a cathode surface and an anode surface. A first electrolyte membrane is sandwiched between the cathode surfaces of the anode plate and the common plate, and a second electrolyte membrane is sandwiched between the anode surfaces of the cathode plate and the common plate, thereby forming two battery cells in the stacking direction. Under the condition that the same number of battery units are formed in the stacking direction of the fuel battery, the number of the bipolar plates can be reduced by the aid of the repeated components of the three bipolar plates, the fuel battery is lower in cost, thinner in thickness, lighter in weight and smaller in specific heat capacity, the power density is improved, meanwhile, the assembly time is shortened, the assembly efficiency and the accuracy consistency are improved, and therefore the overall performances such as high-current discharge capacity, reliability and stability of the fuel battery stack are improved.

In the repeated parts of the three bipolar plates, the opposite surfaces of the common bipolar plate are all contacted with the electrolyte membrane assembly, which not only makes the peripheral sealing of the common bipolar plate very difficult, but also in the use environment, the bipolar plate may be deformed to tear the electrolyte membrane under the condition of temperature change. If the seal of the common bipolar plate is defective or the electrolyte membrane is broken, "cross-gassing" of fuel fluid and oxidizing gas may occur between the anode plate and the cathode surface of the common plate, and between the cathode plate and the anode surface of the common plate, resulting in a reduction in the power generation efficiency of the fuel cell or even damage.

Therefore, better solutions are desired in the industry to further improve the sealing of bipolar plates in fuel cells to improve high current discharge capability, reliability and stability.

SUMMERY OF THE UTILITY MODEL

In view of the above problems, it is an object of the present invention to provide a fuel cell and a repeating member for a fuel cell, in which the number of bipolar plates is reduced using a common plate, and sealing performance is improved using a frame of a membrane electrode assembly.

According to a first aspect of the present invention, there is provided a repeating unit for a fuel cell, comprising: a plurality of bipolar plates including an anode plate, a cathode plate, and a common plate between the anode plate and the cathode plate; a first membrane electrode assembly positioned between the anode plate and the common plate; and a second membrane electrode assembly positioned between the cathode plate and the common plate, wherein each of the first membrane electrode assembly and the second membrane electrode assembly comprises a frame and a multi-layer membrane stack, the frame supporting the multi-layer membrane stack and being in sealing contact with the plurality of bipolar plates.

Preferably, the multilayer film stack comprises: an electrolyte membrane having a first surface and a second surface opposite to each other; an anode catalyst layer and an anode diffusion layer sequentially stacked on the first surface of the electrolyte membrane; and a cathode catalyst layer and a cathode diffusion layer sequentially stacked on the second surface of the electrolyte membrane.

Preferably, the peripheral frame comprises a first sub-frame and a second sub-frame, the first and second sub-frames each comprising a central opening, at least some of the film edges of the multilayer film stack being sandwiched between the first and second sub-frames and exposing a first area at the central opening of the first sub-frame and a second area at the central opening of the second sub-frame.

Preferably, the frame comprises a central opening, at least some of the film edges of the multilayer film stack being heat-pressed over the edges of the central opening, the surface of the multilayer film stack having a first area, a second area being exposed at the central opening of the frame.

Preferably, the intermediate opening defines an area of an active region of the multilayer film stack such that the active region area of the first surface of the electrolyte membrane in the multilayer film stack is a first area and the active region area on the second surface of the electrolyte membrane is a second area, the first area being greater than the second area.

Preferably, the plurality of bipolar plates respectively include first and second surfaces opposite to each other, and the first surface of the anode plate, the first surface of the cathode plate, and the first and second surfaces of the common plate are respectively formed with a plurality of flow channels having a reactant flow field structure.

Preferably, the second surface of the anode plate and the second surface of the cathode plate are respectively provided with a plurality of flow channels of a cooling flow field structure.

Preferably, the method further comprises the following steps: a plurality of seal frames disposed in seal grooves at peripheral portions of the plurality of bipolar plates.

Preferably, the plurality of bipolar plates, the plurality of sealing frames, and the membrane electrode assembly include a first group of through-holes, a second group of through-holes, and a third group of through-holes on the side edges, respectively, which are connected in the stacking direction to form a main line for conveying a fuel fluid, an oxidizing gas, and a cooling medium.

Preferably, the sealing frame separates the first, second and third sets of through-holes from each other and the flow field structure is in communication with a respective set of through-holes of the first, second and third sets of through-holes and separated from the remaining sets of through-holes.

According to a second aspect of the present invention, there is provided a fuel cell, comprising: the repeating member described above; a first current collector and a first insulating plate sequentially stacked on the first surface of the repeating part; a second current collector and a second insulating plate sequentially stacked on a second surface of the repeating part; and a first end plate and a second end plate, the first end plate and the second end plate clamping the repeating component, and the first current collector, the second current collector, the first insulating plate, the second insulating plate.

According to the fuel cell of the embodiment of the present invention, the repeating unit includes, for example, three bipolar plates, and two membrane electrode assemblies sandwiched between the adjacent bipolar plates. The membrane electrode assembly includes a frame and a multi-layer membrane stack, a peripheral portion of the bipolar plate is in sealing contact with the frame of the membrane electrode assembly, and a flow field structure of the bipolar plate is adjacent to a surface of the multi-layer membrane stack of the membrane electrode assembly to provide a fuel fluid and an oxidizing gas. The repeating members form two battery cells in the stacking direction. Under the condition that the same number of battery units are formed in the stacking direction of the fuel battery, the number of the bipolar plates can be reduced by the aid of the repeated components of the three bipolar plates, the fuel battery is lower in cost, thinner in thickness, lighter in weight and smaller in specific heat capacity, the power density is improved, meanwhile, the assembly time is shortened, the assembly efficiency and the accuracy consistency are improved, and therefore the overall performances such as high-current discharge capacity, reliability and stability of the fuel battery stack are improved. Further, in the repeating parts of the fuel cell, the peripheries of the bipolar plates are brought into sealing contact with the rim of the membrane electrode assembly, and "cross-talk" of fuel fluid and oxidizing gas between adjacent bipolar plates can be prevented. In the using state, even if the bipolar plate deforms due to environmental temperature change or uneven pressure, the frame of the membrane electrode assembly can reduce the acting force applied to the multilayer film lamination, so that the integrity of the electrolyte membrane is maintained. Therefore, structural improvement of the repetitive parts in the fuel cell can also improve the large-current discharge capability, reliability, and stability.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.

Fig. 1 is a schematic perspective view showing an exploded state of a fuel cell according to an embodiment of the present invention.

Fig. 2 shows a schematic cross-sectional view of a repeating component in a fuel cell according to an embodiment of the present invention.

Fig. 3 is a schematic perspective view showing a disassembled state of a repeating unit in a fuel cell according to an embodiment of the present invention.

Fig. 4a, 4b and 4c show top views of a first sub-frame, a second sub-frame, a multilayer film stack, respectively, of a membrane electrode assembly in a fuel cell according to an embodiment of the present invention.

Reference numerals

100 fuel cell

110 first end plate

120 second end plate

140 tension plate

150 interface board

131 first insulating plate

132 first current collector

133 repeat element

134 second current collector

135 second insulating plate

141 lower flange

142 upper flange

143 screw hole

11 anode plate

21 cathode plate

31 common electrode plate

41 sealing frame

42 shim

51 Main pipeline

12,13,22,23,32,33 flow channel

14,24,34 seal groove

10 membrane electrode assembly

20 multilayer film stack

1 electrolyte membrane

2 anode catalyst layer

3 cathode catalyst layer

4 anode diffusion layer

5 cathode diffusion layer

6 rims

6a first subframe

6b second subframe

Detailed Description

In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the accompanying drawings. The preferred embodiments of the present invention are shown in the drawings. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

In the present application, the term "bipolar plate" means a conductive plate in contact with a membrane electrode assembly in a fuel cell, and mainly functions to transport reaction substances using a flow field of a surface, and to collect and conduct electricity, heat and water generated by the reaction. The bipolar plate is, for example, any one of an anode plate, a cathode plate, and a common plate. Further, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

The present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 is a schematic perspective view showing an exploded state of a fuel cell according to an embodiment of the present invention. The fuel cell 100 includes a first end plate 110 and a second end plate 120 opposite to each other, between which a first insulating plate 131, a first current collector 132, a repeating part (repeat part)133, a second current collector 134, and a second insulating plate 135 are sequentially stacked. First end plate 110 also serves as a distribution device for distributing fuel fluid, oxidizing gas, and cooling medium to the bipolar plates in repeating unit 133.

The fuel fluid includes gaseous hydrogen, or liquid methanol or methanol solution. The oxidizing gas may be air or pure oxygen, and the cooling medium may be liquid or gas.

Repeating unit 133 includes bipolar plates and a membrane electrode assembly sandwiched between the bipolar plates. The repeating unit 133 is substantially rectangular in shape in a plane perpendicular to the stacking direction, and a first group of main lines, a second group of main lines, and a third group of main lines extending in the stacking direction are provided at side portions of the rectangle for supplying the fuel fluid, the oxidizing gas, and the cooling medium to the respective flow fields in the bipolar plates, respectively.

The cell stack of the fuel cell includes, for example, a plurality of repeating units 133 stacked together and electrically connected to each other to increase the output voltage.

The first current collector 132 and the cathode plate of the repeating unit 133 are in contact with each other, both of which are composed of an electrically conductive material, thereby forming an electrically conductive path on the cathode side. The second current collector 134 and the anode plate of the repeating unit 133 are in contact with each other, both of which are composed of an electrically conductive material, thereby forming an electrically conductive path on the anode side. The first current collector 132 and the second current collector 134 may be made of a material having high electrical conductivity, such as copper plate or aluminum. In this embodiment, the anode plate and the cathode plate of the repeating unit 133 serve as a reactant flow field device, a heat sink, and a conductive and supporting structure, so that the structure of the fuel cell can be simplified and the volume of the fuel cell can be reduced.

The first insulating plate 131 is positioned between the first current collector 132 and the first end plate 110, and the second insulating plate 135 is positioned between the second current collector 134 and the second end plate 120, thereby isolating the repeating parts and the current collectors and the first and

second end plates

110 and 120 from each other. In the case where the fuel cell 100 includes a plurality of repeating components, the plurality of repeating components are stacked between the first current collector 132 and the second current collector 134. The side portions of the first insulating plate 131 and the first current collector 132 are respectively formed with a plurality of through-holes, which are aligned with the plurality of through-holes of the side portion of the repeating member 133, thereby together forming a plurality of main lines extending in the stacking direction, for example, a first group of main lines for flowing in and out the fuel fluid, a second group of main lines for flowing in and out the oxidizing gas, and a third group of main lines for flowing in and out the cooling medium.

The fuel cell 100 further includes two tension plates 140 that form a clamping arrangement with the first end plate 110 and the second end plate 120. Two tension plates 140 are located on opposite sides of the fuel cell 100 and each include a lower flange 141 and an upper flange 142. The lower flange 141 of the tension plate 140 is in contact with the bottom surface edge of the first end plate 110, and the upper flange 142 is in contact with the top surface edge of the second end plate 120, thereby forming a clamping means for fixing the first insulation plate 131, the first current collector 132, the repeating unit 133, the second current collector 134, and the second insulation plate 135 together by applying pressure to the first end plate and the second end plate using the upper and lower flanges of the tension plate 140. Preferably, the upper flange 142 of the tension plate 140 has a plurality of screw holes 143, and additional pressure is applied to the surface of the second end plate 120 using bolts passing through the plurality of screw holes 143. Preferably, a sealing frame is provided between the stacked layers, thereby forming a seal of the stacked layers while fixing the stacked layers.

In this embodiment, the first end plate 110 doubles as a flow distribution device. A first pair of manifolds for providing inflow and outflow passages for fuel fluid, a second pair of manifolds for providing inflow and outflow passages for oxidizing gas, and a third pair of manifolds for providing inflow and outflow passages for cooling medium are formed in the first end plate. With the first and

second end plates

110, 120 secured together, the open top ends of a first pair of manifolds in the first end plate 110 are aligned with a first set of main conduits in the membrane electrode assemblies 10 in the repeating section 133, the open top ends of a second pair of manifolds in the first end plate 110 are aligned with a second set of main conduits in the membrane electrode assemblies 10 in the repeating section 133, and the open top ends of a third pair of manifolds in the first end plate 110 are aligned with a third set of main conduits in the membrane electrode assemblies 10 in the repeating section 133. The end face of the first end plate 110 has side open ends of the first, second and third pairs of manifolds formed thereon.

The fuel cell 100 further includes two interface plates 150 connected to end faces of the first end plate 110. The two interface boards 150 each include a plurality of pipe interfaces for connecting a plurality of external pipes. The open ends of the plurality of pipe interfaces in the interface plate 150 and the open ends of the first, second, and third pairs of manifolds in the first end plate 110 are aligned with one another to provide communication with one another.

According to the fuel cell 100 of the embodiment, the first end plate 110 serves not only as a component of the distribution device but also as a component of the clamping device, and the tension plate 140 serves not only as a side surface protection component of the fuel cell 100 but also as a component of the clamping device, and the internal stacked layers of the fuel cell 100 are fixed by applying pressure to the first end plate 110 and the second end plate 120 by the upper and lower flanges of the tension plate, thereby performing a fastening function.

According to the fuel cell 100 of the embodiment, the repeating unit 133 includes three bipolar plates, and two membrane electrode assemblies sandwiched between the adjacent bipolar plates. The membrane electrode assembly includes a frame and a multi-layer membrane stack 20, with peripheral portions of the bipolar plates being in sealing contact with the frame of the membrane electrode assembly and flow field structures of the bipolar plates being adjacent to a surface of the multi-layer membrane stack 20 of the membrane electrode assembly to provide fuel fluid and oxidizing gas. The repeating unit 133 forms two battery cells in the stacking direction. Under the condition that the same number of battery units are formed in the stacking direction of the fuel cell, the number of the bipolar plates can be reduced by the repeated components 133 of the three bipolar plates, the cost is lower, the thickness is thinner, the weight is lighter, the specific heat capacity is smaller, the power density is improved, meanwhile, the assembly time is reduced, the assembly efficiency and the accuracy consistency are improved, and therefore the overall performances such as the large-current discharge capacity, the reliability and the stability of the electric pile are improved.

Further, in the repeating parts of the fuel cell 100, the peripheries of the bipolar plates are brought into sealing contact with the rim of the membrane electrode assembly, and "cross-talk" of fuel fluid and oxidizing gas between adjacent bipolar plates can be prevented. In the use state, even if the environment temperature change of the bipolar plate generates deformation, the frame of the membrane electrode assembly can reduce the acting force applied to the multilayer film lamination 20, thereby maintaining the integrity of the electrolyte membrane. Therefore, structural improvement of the repeat unit 133 in the fuel cell 100 can also improve the large-current discharge capability, reliability, and stability.

Fig. 2 shows a schematic cross-sectional view of a repeating component in a fuel cell according to an embodiment of the present invention. The repeating member is used, for example, in the fuel cell 100 shown in fig. 1.

The repeating unit 133 includes three bipolar plates, i.e., an anode plate 11, a common plate 31, and a cathode plate 21, which are sequentially stacked. The bipolar plate can be made of at least one of graphite plate, silicon, aluminum alloy, titanium alloy, brass or stainless steel sheet, the thickness is 0.1-2um, and the surface of the bipolar plate can be coated or not. The forming process of the bipolar plate can be stamping, molding, engraving, etching or printing.

The bipolar plate comprises a first surface and a second surface opposite to each other, and a first set of through holes, a second set of through holes and a third set of through holes on the sides opposite to each other. A flow field structure is formed on each of the first and second surfaces of the bipolar plate, the flow field structure including a plurality of flow channels separated from each other by ridges. The first, second and third sets of through-holes are part of a first, second and third set of primary conduits, respectively, extending in the stacking direction for providing a fuel fluid, an oxidizing gas and a cooling medium to respective flow field structures in the bipolar plate. The reactant flow field structure of the first surface of the anode plate 11 comprises a plurality of flow channels 12 in communication with the first set of through-holes and the cooling flow field structure of the second surface comprises a plurality of flow channels 13 in communication with the third set of through-holes. The reactant flow field structure of the first surface of the cathode plate 21 comprises a plurality of flow channels 22 in communication with the second set of through-holes and the cooling flow field structure of the second surface comprises a plurality of flow channels 23 in communication with the third set of through-holes. The reactant flow field structure of the first surface of the common plate 31 comprises a plurality of flow channels 32 in communication with the second set of through-going apertures and the reactant flow field structure of the second surface comprises a plurality of flow channels 33 in communication with the first set of through-going apertures.

The reactant flow field structure of the bipolar plate adopts an ultra-fine dense flow field design, for example, the ridge width between the flow channels is 0.03-0.5mm, the groove width of the flow channels is 0.03-0.5mm, and the groove depth is 0.03-0.5 mm. In the cooling flow field structure, the ridge width between the flow channels is 0.1-2mm, the groove width is 0.1-2mm, and the groove depth is 0.03-0.5 mm. In a preferred flow field configuration, the cross-sectional area of the oxidant gas flow channels is greater than the cross-sectional area of the cooling medium flow channels, which are greater than the cross-sectional area of the fuel fluid flow channels. For example, the cross-sectional area of the oxidizing gas flow path is 1.5 to 5 times the cross-sectional area of the cooling medium flow path and 1.5 to 10 times the cross-sectional area of the fuel fluid flow path, and the cross-sectional area of the cooling medium flow path is 1.5 to 4 times the cross-sectional area of the fuel fluid flow path.

Between the first surface of the anode plate 11 and the first surface of the common plate 31, and between the first surface of the cathode plate 21 and the second surface of the common plate 31, the membrane electrode assemblies 10 are sandwiched, respectively, thereby forming two unit cells in the stacking direction. The flow channels 12 of the anode plate 11 are open on the first surface, and the fuel fluid is transferred in the direction of the flow channels 12 and delivered to the anode side of the membrane electrode assembly 10. The flow channels 22 of the cathode plate 21 are open on the first surface, and the oxidizing gas is delivered in the direction of the flow channels 22 and delivered to the cathode side of the membrane electrode assembly 10. The flow channels 32 of the common plate 31 are open on the first surface, the oxidizing gas is delivered in the direction of the flow channels 32 and is delivered to the cathode side of the membrane electrode assembly 10, the flow channels 33 are open on the second surface, and the fuel fluid is delivered in the direction of the flow channels 33 and is delivered to the anode side of the membrane electrode assembly 10.

The membrane electrode assembly 10 includes a multilayer film stack 20 and a frame 6. Referring to fig. 4a, 4b and 4c, the peripheral frame 6 comprises, for example, a first subframe 6a and a second subframe 6b, for example consisting of polyphenylene sulfide (PPS) or polyethylene naphthalate (PEN).

The first subframe 6a and the second subframe 6b each comprise a central opening, at least some of the film edges of the multilayer film stack 20 being sandwiched between the first subframe 6a and the second subframe 6b and exposing a first area at the central opening of the first subframe 6a and a second area at the central opening of the second subframe 6 b. Further, the first sub-frame 6a and the second sub-frame 6b comprise a first set of through-holes, a second set of through-holes and a third set of through-holes, respectively, on opposite sides to each other. In the assembled state of the membrane electrode assembly 10, the sets of through-holes of the first subframe 6a and the second subframe 6b communicate respectively to form a part of a continuous main line.

The intermediate openings of the first sub-frame 6a and the second sub-frame 6b not only support the multilayer film stack 20, but also define the area of the active region of the multilayer film stack 20. Preferably, the area of the anode-side active region (i.e., the first area) of the multilayer film stack 20 is slightly larger than the area of the cathode-side active region (i.e., the second area) to reduce serious quality problems caused by the oxidizing gas passing through the cathode catalytic layer, so as to improve the overall performance of the cell, such as cell safety and reliability, stability, and the like.

The bipolar plate is formed with a seal groove in the peripheral portion thereof for providing a seal frame 41. For example, the sealing groove 14 is formed on the first and second surfaces of the anode plate 11, the sealing groove 24 is formed on the first and second surfaces of the cathode plate 21, and the sealing groove 34 is formed on the first and second surfaces of the common plate 31. The sealing frame 41 is made of at least one selected from silicone rubber, fluororubber, and Ethylene Propylene Diene Monomer (EPDM), for example. The sealing frame 41 is formed by injection molding or cutting, for example, and may be fitted with a dispensing process to form a seal. The sealing frame 41 includes a first set of through-holes, a second set of through-holes, and a third set of through-holes on opposite sides of each other. In the assembled state of the repeating parts, the peripheral parts of the bipolar plate are brought into sealing contact with the peripheral portions of the frame of the membrane electrode assembly. The first set of through holes, the second set of through holes, and the third set of through holes of the bipolar plate are aligned with the first set of through holes, the second set of through holes, and the third set of through holes of the sealing frame, and the first set of through holes, the second set of through holes, and the third set of through holes of the frame of the membrane electrode assembly, respectively, to form a continuous main pipeline 51 for conveying fuel fluid, oxidizing gas, and cooling medium.

The multilayer film stack 20 includes an electrolyte membrane 1, and an anode catalyst layer 2, an anode diffusion layer 4 stacked in this order on a first surface (fuel gas side) of the electrolyte membrane 1, and a cathode catalyst layer 3, a cathode diffusion layer 5 stacked in this order on a second surface (oxidizing gas side) of the electrolyte membrane 1.

The electrolyte membrane 1 is a selectively permeable membrane that transports protons and has a function of insulating electrons. The electrolyte membrane 1 is roughly classified into a fluorine-based electrolyte membrane 1 and a hydrocarbon-based electrolyte membrane 1 depending on the kind of the ion exchange resin which is a constituent material. Among them, the fluorine-based electrolyte membrane 1 has a C-F bond (C-F bond), and therefore is excellent in heat resistance and chemical stability. For example, as the electrolyte membrane 1, a perfluorosulfonic acid membrane known by a trade name of Nafion (registered trademark, dupont co., ltd.) is widely used.

The anode catalyst layer 2 contains an electrode catalyst supporting a catalyst component and a polymer. The electrode catalyst has a function of promoting a reaction (hydrogen-oxygen reaction) of dissociating hydrogen into protons and electrons. The electrode catalyst has a structure in which a catalyst component such as platinum is supported on the surface of a conductive carrier made of carbon or the like, for example.

The cathode catalyst layer 3 contains an electrode catalyst supporting a catalyst component and a polymer. The electrode catalyst has a function of promoting a reaction of producing water from protons, electrons, and oxygen (oxygen reduction reaction). The electrode catalyst has a structure in which a catalyst component such as platinum is supported on the surface of a conductive carrier made of carbon or the like, for example.

The anode diffusion layer 4 and the cathode diffusion layer 5 are respectively made of porous loose conductive materials, such as porous carbon paper materials, and the anode diffusion layer 4 and the cathode diffusion layer 5 uniformly diffuse fuel fluid and oxidizing gas from flow channels of a flow field onto the two side surfaces of the catalytic layer of the electrolyte membrane 1 respectively so that the fuel fluid and the oxidizing gas are respectively in contact with the anode catalyst layer 2 and the cathode catalyst layer 3.

On the anode side of the membrane electrode assembly 10, the fuel fluid diffuses through the anode diffusion layer 4 of the membrane electrode assembly 10 to the anode catalyst layer 2, the fuel fluid generates cations and electrons through an electrochemical reaction on the anode catalyst layer 2 of the membrane electrode assembly 10, the cations migrate to the cathode side via the electrolyte membrane, and the electrons are conducted to the anode plate 11 via the anode diffusion layer 4. The electrons then pass from the anode side to the cathode side of the membrane electrode assembly 10 via an external circuit. On the cathode side of the membrane electrode assembly 10, electrons are conducted to the cathode diffusion layer 5 via the cathode plate 12 and then conducted to the cathode catalyst layer 3 of the membrane electrode assembly 10, and the oxidizing gas is diffused to the cathode catalyst layer 3 through the cathode diffusion layer 5 of the membrane electrode assembly 10, and the oxidizing gas combines with the electrons to form anions, which in turn combine with the cations transferred through the electrolyte membrane to generate water, thereby forming a current loop.

In the above-described embodiments, it is described that the peripheral frame in the membrane electrode assembly includes the first sub-frame and the second sub-frame, the multilayer film stack is sandwiched therebetween, and the area of the active region of the multilayer film stack is defined with the intermediate openings of the first sub-frame and the second sub-frame. In an alternative embodiment, the membrane electrode assembly comprises a single subframe, at least some of the film edges of the multilayer film stack being heat-staked to the edges of said central opening, the surface of the multilayer film stack having a first area, the second area being exposed at the central opening of the frame.

Fig. 3 is a schematic perspective view showing a disassembled state of a repeating unit in a fuel cell according to an embodiment of the present invention. This repeating member is used, for example, in the fuel cell 100 shown in fig. 1, and a more detailed and preferable structure will be described below with reference to fig. 3.

In this embodiment, the repeating unit 133 includes a plurality of bipolar plates, i.e., an anode plate 11, a cathode plate 21, and a common plate 31. The bipolar plate comprises a first surface and a second surface opposite to each other, and a first set of through holes, a second set of through holes and a third set of through holes on the sides opposite to each other. And flow field structures and flow guide structures positioned between the flow field structures and the corresponding group of through holes are respectively formed on the first surface and the second surface of the bipolar plate. The set of through-holes includes a transverse opening. The flow guiding structure comprises a plurality of flow guiding grooves distributed in a radial shape, and the flow guiding grooves extend from the transverse opening of the through hole to the inlet or the outlet of the flow field structure so as to be used as inflow channels or outflow channels. The plurality of channels of the bipolar plate are open at the surface. Preferably, the gasket 42 is used to seal the plurality of channels to form upper closed channels, so as to prevent the channels from being blocked by the frame of the membrane electrode assembly, which is deformed by pressure when the fuel cell is assembled and compressed.

A seal groove is formed in the peripheral portion of the bipolar plate. A sealing frame 41 is disposed in the sealing groove of the bipolar plate, for example, to form a seal in cooperation with a dispensing process. The sealing frame 41 includes a first set of through-holes, a second set of through-holes, and a third set of through-holes on opposite sides of each other. The sealing frame 41 not only separates the first, second and third sets of through holes from each other, but also communicates the flow field structure on the surface of the bipolar plate with the corresponding set of through holes and separates the flow field structure from the other two sets of through holes, so as to seal the periphery of the bipolar plate and the membrane electrode assembly.

In the assembled state of the repeating parts, the peripheral parts of the bipolar plate are brought into sealing contact with the peripheral portions of the frame of the membrane electrode assembly. The first set of through holes, the second set of through holes, and the third set of through holes of the bipolar plate are aligned with the first set of through holes, the second set of through holes, and the third set of through holes of the sealing frame, and the first set of through holes, the second set of through holes, and the third set of through holes of the frame of the membrane electrode assembly, respectively, to form a continuous main pipeline 51 for conveying fuel fluid, oxidizing gas, and cooling medium.

It should be noted that in the description of the present invention, the contained terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Finally, it should be noted that: it should be understood that the above-mentioned embodiments are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And need not be exhaustive of all embodiments. And obvious changes and modifications may be made without departing from the scope of the present invention.

Claims

1. A repeating component for a fuel cell, comprising:

a plurality of bipolar plates including an anode plate, a cathode plate, and a common plate between the anode plate and the cathode plate;

a first membrane electrode assembly positioned between the anode plate and the common plate; and

a second membrane electrode assembly positioned between the cathode plate and the common plate,

wherein each of the first and second membrane electrode assemblies comprises a frame and a multi-layer membrane stack, the frame supporting the multi-layer membrane stack and being in sealing contact with the plurality of bipolar plates.

2. The repeating component of claim 1, wherein the multilayer film stack comprises:

an electrolyte membrane having a first surface and a second surface opposite to each other;

an anode catalyst layer and an anode diffusion layer sequentially stacked on the first surface of the electrolyte membrane; and

a cathode catalyst layer and a cathode diffusion layer sequentially stacked on the second surface of the electrolyte membrane.

3. A repeat member according to claim 2, wherein the peripheral frame comprises a first subframe and a second subframe, the first and second subframes each comprising a central opening, at least some of the film edges of the multilayer film stack being sandwiched between the first and second subframes, and a first area being exposed at the central opening of the first subframe and a second area being exposed at the central opening of the second subframe.

4. The repeating component of claim 2, wherein the frame includes a central opening, at least some of the film edges of the multilayer film stack are heat staked over the edges of the central opening, the surface of the multilayer film stack has a first area, and a second area is exposed at the central opening of the frame.

5. The repeating component of claim 3 or 4 wherein the intermediate opening defines an area of an active region of the multilayer film stack such that the active region area of the first surface of the electrolyte film in the multilayer film stack is a first area and the active region area on the second surface of the electrolyte film is a second area, the first area being greater than the second area.

6. The repeating component of claim 1, wherein the plurality of bipolar plates each include first and second surfaces opposite one another, the first surface of the anode plate, the first surface of the cathode plate, and the first and second surfaces of the common plate each forming a plurality of flow channels having a reactant flow field structure.

7. The repeating component of claim 6, wherein the second surface of the anode plate and the second surface of the cathode plate each have a plurality of flow channels of a cooling flow field structure.

8. The repeating component of claim 6, further comprising: a plurality of seal frames disposed in seal grooves at peripheral portions of the plurality of bipolar plates.

9. The repeating component of claim 8, wherein the plurality of bipolar plates, the plurality of sealing frames, and the membrane electrode assembly comprise a first set of through-holes, a second set of through-holes, and a third set of through-holes on the sides, respectively, the first set of through-holes, the second set of through-holes, and the third set of through-holes being connected in the stacking direction as primary conduits for transporting fuel fluid, oxidizing gas, and cooling medium.

10. The repeating component of claim 9, wherein the sealing frame separates the first, second, and third sets of through-holes from one another and communicates the flow field structure with respective ones of the first, second, and third sets of through-holes and separates the flow field structure from the remaining sets of through-holes.

11. A fuel cell, comprising:

the repeating component of any one of claims 1 to 10;

a first current collector and a first insulating plate sequentially stacked on the first surface of the repeating part;

a second current collector and a second insulating plate sequentially stacked on a second surface of the repeating part; and

a first end plate and a second end plate, the first end plate and the second end plate clamping the repeating component, and the first current collector, the second current collector, the first insulating plate, the second insulating plate.