JP2006114386A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell in which reactivity of power generation cell is enhanced, and which can prevent its drying by flow of a fuel gas and an oxidizer gas. <P>SOLUTION: This is provided with the power generation cell having an electrolyte membrane 2, and a separator 3 opposed to the power generation cell, and on the surface of the power generation cell side of the separator 3, a groove-like gas supply passage 11 which supplies the fuel gas or the oxidizer gas to the power generation cell, and a groove-like gas discharge passage 12 which recovers the fuel gas or the oxidizer gas after reaction of the power generation cell are formed so as to respectively mesh with each other to have a comb-shape, and opening part width of the gas supply passage 11 and the gas discharge passage 12 respectively is smaller than the maximum width of the gas supply passage 11 and the gas discharge passage 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell including a power generation cell and a separator.

  A fuel cell is a device that generally obtains electric energy using hydrogen and oxygen as fuel. This fuel cell has been developed widely as a future energy supply system because it is environmentally friendly and can realize high energy efficiency.

  In this fuel cell, a separator comprising an electrode plate in which a fluid passage for supplying a fuel gas containing hydrogen is formed on both sides of an electrolyte membrane made of a solid polymer or the like, and a fluid for supplying an oxidant gas containing oxygen There is known one provided with a separator made of an electrode plate in which a passage is formed.

  A technique is disclosed in which the gas supply flow path and the gas discharge flow path are separated into a comb shape so as to engage with each other in the separator (see, for example, Patent Document 1). According to this technique, the reaction between the fuel gas and the oxidant gas is efficiently performed in the entire separator reaction zone.

  Further, a technique is disclosed in which the opening width is small and the bottom width is large on the upstream side of the fluid passage, and the opening width is large and the bottom width is small on the downstream side of the fluid passage ( For example, see Patent Document 2.) According to this technique, since the gas that has not reacted on the upstream side contributes to the reaction on the downstream side, the reaction is performed almost evenly in the entire reaction zone.

Furthermore, a technique is disclosed in which the width of the supply flow path is increased on the gas diffusion layer side (see, for example, Patent Document 3). According to this technique, it is possible to prevent the generated water on the supply flow path side from being excessively discharged.
JP-A-11-16591 JP 2001-43870 A JP 2004-47213 A

  However, in the technique of Patent Document 1, if the channel width of the gas supply channel and the gas discharge channel is reduced in order to improve the reaction efficiency, the gas flow rate may increase and the power generation cell may dry. . Moreover, in the technique of patent document 2, since the contact area of a separator and a power generation cell reduces in the downstream of a fluid channel | path, an efficient reaction is not performed. Furthermore, in the technique of Patent Document 3, since the contact area between the separator and the power generation cell is small, an efficient reaction is not performed.

  An object of the present invention is to provide a fuel cell capable of improving the reactivity of a power generation cell and preventing the power generation cell from drying due to the flow of fuel gas and oxidant gas.

  A fuel cell according to the present invention includes a power generation cell having an electrolyte membrane and a separator facing the power generation cell, and a groove-like surface for supplying fuel gas or oxidant gas to the power generation cell on the power generation cell side surface of the separator. The gas supply flow path and the groove-like gas discharge flow path for collecting the reacted fuel gas or oxidant gas from the power generation cell are formed so as to be interdigitated with each other. The opening width of the gas discharge flow path is smaller than the maximum width of the gas supply flow path and the gas discharge flow path, respectively.

  In the fuel cell according to the present invention, the fuel gas or oxidant gas supplied to the gas supply channel is supplied to the power generation cell, and the reacted fuel gas or oxidant gas is discharged from the power generation cell to the gas discharge channel. The In this case, since the opening width of the gas supply flow path and the gas discharge flow path is smaller than the maximum width of the supply flow path and the gas discharge flow path, the water generated by the power generation of the power generation cell is excessively drained. Can be prevented.

  Further, since the opening widths of the gas supply channel and the gas discharge channel are small, the contact area between the power generation cell and the separator increases. Thereby, the electric current generated from the power generation cell can be efficiently recovered through the separator. As a result, the reactivity of the power generation cell is improved.

  Furthermore, since the areas of the bottom surfaces of the gas supply channel and the gas discharge channel are increased, the contact area between the separators is increased. Thereby, the contact resistance of a separator can be made small.

  In addition, since the cross-sectional areas of the gas supply flow path and the gas discharge flow path are larger than the cross-sectional area when the flow path width is constant at the opening width, the flow rate of the fuel gas or oxidant gas becomes excessive. This can be prevented. Thereby, drying of a power generation cell can be prevented. As a result, a decrease in power generation efficiency of the power generation cell can be prevented.

  The separator may be made of a conductive plate, and the gas supply channel and the gas discharge channel may be formed by pressing the conductive plate. In this case, the manufacturing process is simplified as compared with the case of cutting the separator surface. Therefore, the cost can be reduced.

  The separator may be a press metal. In this case, the separator can be easily processed. As a result, the manufacturing process can be shortened and the cost can be reduced.

  The groove on the surface opposite to the power generation cell of the separator may be a coolant flow path through which a coolant for cooling the fuel cell flows. In this case, the cooling medium flow path can use a groove obtained by pressing the separator to form the flow path. Thus, since the grooves formed on both surfaces of the separator are used for the gas flow path and the cooling medium flow path, the fuel cell can be thinned.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that the water produced | generated by the electric power generation of the power generation cell is drained excessively. Moreover, the electric current generated from the power generation cell can be efficiently recovered through the separator. As a result, the reactivity of the power generation cell is improved. Furthermore, the contact resistance of the separator can be reduced. Further, it is possible to prevent the flow rate of the fuel gas or the oxidant gas from becoming excessively large. Thereby, drying of a power generation cell can be prevented. As a result, a decrease in power generation efficiency of the power generation cell can be prevented.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 is a schematic cross-sectional perspective view of a fuel cell 100 according to the present invention. As shown in FIG. 1, the fuel cell 100 has a structure in which a plurality of unit cells 20 each provided with a separator 3 are stacked on both surfaces of a power generation cell 10. The power generation cell 10 has a structure in which a catalyst layer 5 and a gas diffusion layer 4 are sequentially laminated on both surfaces of the electrolyte membrane 2.

  As the electrolyte membrane 2, for example, a solid polymer electrolyte membrane or the like is used. This solid polymer electrolyte membrane is composed of a polymer having proton conductivity. For the catalyst layer 5, a carbon-supported platinum catalyst or the like can be used. For the gas diffusion layer 4, carbon paper or the like excellent in gas permeability and conductivity can be used. The separator 3 is made of a metal plate.

  Hydrogen in the fuel gas supplied from one separator 3 permeates the gas diffusion layer 4 due to the diffusion effect, and is separated into protons and electrons in the catalyst layer 5. This proton moves through the electrolyte membrane 2. Oxygen in the oxidant gas supplied from the other separator 3 permeates the gas diffusion layer 4 due to the diffusion effect, and reacts with protons in the catalyst layer 5 to generate water. Power generation by the power generation cell 10 is performed by the above process. The current obtained by the power generation of the power generation cell 10 is collected by the separator 3.

  FIG. 2 is a diagram for explaining the details of the separator 3. FIG. 2A is a plan view of the separator 3 on the diffusion layer 4 side, and FIG. 2B is a cross-sectional view of the separator 3. As shown in FIG. 2A, a gas supply channel 11 and a gas discharge channel 12 are formed on the surface of the separator 3 on the diffusion layer 4 side. The gas supply channel 11 includes a gas supply port 11a, a plurality of comb-shaped channels 11b, and a gas distribution channel 11c that supplies gas to the plurality of comb-shaped channels 11b. The gas discharge channel 12 includes a gas discharge port 12a, a plurality of comb-shaped channels 12b, and a gas recovery channel 12c that recovers gas from the plurality of comb-shaped channels 12b. The gas supply channel 11 and the gas discharge channel 12 are formed such that the comb-shaped channels 11b and 12b are engaged with each other. The gas supply channel 11 and the gas discharge channel 12 can be formed by pressing the separator 3.

  The fuel gas or oxidant gas supplied to the gas supply port 11a flows through the gas distribution channel 11c, is supplied to the tooth-like channel 11b, is supplied to the gas diffusion layer 4 of FIG. It is used for power generation and discharged to the comb-shaped channel 12b. The fuel gas or oxidant gas discharged to the comb-shaped flow path 12b flows through the recovery flow path 12c and is discharged to the outside from the gas discharge port 12a.

  Next, a cross section of the separator 3 will be described. As shown in FIG. 2B, the channel widths of the comb-like channels 11b and 12b become smaller as they approach the diffusion layer 4, and the fuel gas or the oxidation gas flowing through the comb-like channels 11b and 12b. The contact area between the agent gas and the diffusion layer 4 is reduced. Thereby, it can prevent that the water produced | generated by the electric power generation of the power generation cell 10 is drained excessively.

  Moreover, since the contact area of the gas diffusion layer 4 and the separator 3 will become large when the opening part width | variety of the comb-tooth shaped flow paths 11b and 12b is small, the electric current which generate | occur | produced from the electric power generation cell 10 can be collect | recovered efficiently. Thereby, the reactivity of the power generation cell 10 is improved.

  Furthermore, since the areas of the bottom surfaces of the comb-shaped channels 11b and 12b are increased, the contact area between the separators 3 is increased. Thereby, the contact resistance of the separator 3 can be reduced.

  Moreover, since the cross-sectional area of the comb-shaped flow paths 11b and 12b is larger than the cross-sectional area when the flow path width is constant at the opening width, the flow rate of the fuel gas or the oxidant gas becomes excessive. Can be prevented. Thereby, drying of the diffusion layer 4 can be prevented. As a result, a decrease in power generation efficiency of the power generation cell 10 can be prevented.

  In addition, since the opening width of the comb-shaped channel 11b is small, the contact area between the fuel gas or the oxidant gas flowing through the comb-shaped channel 11b and the diffusion layer 4 is small, but the comb-shaped channel 11b. The fuel gas or oxidant gas supplied to the gas passes through the gas diffusion layer 4 and is discharged to the tooth-shaped flow path 12b. Therefore, unlike the case of using a separator having a normal flow path having an inlet and an outlet, the power generation efficiency of the power generation cell 10 does not decrease.

  A cooling medium flow path 6 through which a cooling medium for cooling the fuel cell 100 flows is formed on the surface of the separator 3 opposite to the gas diffusion layer 4. As the cooling medium, for example, cooling water can be used. The cooling medium flow path 6 includes a groove-shaped flow path obtained by forming the gas supply flow path 11 and the gas discharge flow path 12. As described above, since the groove portions formed on both surfaces of the separator 3 are used for the gas supply channel 11, the gas discharge channel 12, and the cooling medium channel 6, the fuel cell 100 can be thinned. Moreover, since the press work can be easily performed as compared with the cutting process, the manufacturing process of the separator 3 is simplified, and the manufacturing cost can be reduced. Furthermore, since the opening width of the comb-shaped flow paths 11b and 12b is small, the area where the cooling medium flow path 6 contacts the diffusion layer 4 increases. Thereby, the cooling efficiency of the fuel cell 100 is improved.

  FIG. 3 is a cross-sectional view of a separator 3 a that is another example of the separator 3. As shown in FIG. 3, a bent portion is formed at the corner of the opening of the comb-shaped channel 11b. As a result, the fuel gas or oxidant gas flowing through the comb-shaped channel 11 b flows along the bent portion of the opening and is supplied to the gas diffusion layer 4. In this case, the fuel gas or oxidant gas that flows in the vicinity of the bottom surface of the comb-shaped channel 11 b is guided to the gas diffusion layer 4. Thereby, the fuel gas or the oxidant gas is efficiently supplied to the gas diffusion layer 4. As a result, the power generation efficiency of the power generation cell 10 is improved.

  FIG. 4 is a diagram showing an example of a cross section of the comb-shaped channel 11b. As shown in FIG. 4A, the channel width of the comb-shaped channel 11b is constant from the channel bottom surface of the comb-shaped channel 11b to the vicinity of the opening, and is small in the vicinity of the opening. May be. Further, as shown in FIG. 4B, the channel width of the comb-like channel 11b is constant from the bottom surface of the comb-like channel 11b to the vicinity of the opening, and from the vicinity of the opening to the opening. It may be continuously reduced over time. Further, as shown in FIG. 4 (c), the channel width of the comb-shaped channel 11b continuously decreases from the bottom surface of the comb-shaped channel 11b to the opening, and the channel sidewall is the channel. You may make it dent in. Further, as shown in FIG. 4D, the channel width of the comb-shaped flow channel 11b continuously decreases from the bottom surface of the comb-shaped flow channel 11b to the opening, and the channel side wall flows. You may make it project outside the road.

  As described above, if the opening width of the comb-shaped channel 11b is smaller than the maximum channel width, it can be applied to the present invention. Accordingly, the bottom surface of the comb-shaped channel 11b does not necessarily have the maximum channel width. In addition, the cross section of the comb-shaped flow path 11a can also be made into the cross section of Fig.4 (a)-FIG.4 (d).

  FIG. 5 is a diagram for explaining separators 3b and 3c, which are still another example of the separator 3. FIG. FIG. 5A is a cross-sectional view of the separator 3b, and FIG. 5B is a cross-sectional view of the separator 3c. As shown in FIG. 5A, in the separator 3b, the cooling medium flow path 6 of the separator 3 is used as the comb-shaped flow paths 11a and 11b. Further, as shown in FIG. 5B, in the separator 3c, the cooling medium flow path 6 of the separator 3a is used as comb-shaped flow paths 11a and 11b.

  As described above, if the separators 3b and 3c are used in the fuel cell 100, it is not necessary to stack two separators. Thereby, the fuel cell 100 can be thinned.

  In this embodiment, the separator 3 is made of a metal plate, but may be any conductive plate having conductivity and gas impermeability. For example, a carbon plate or the like can be used.

  In the present embodiment, the separators 3, 3a, 3b, 3c are formed by pressing a conductive plate, but may be formed by cutting a carbon plate or the like.

  Furthermore, the present invention may not be applied to a separator that supplies fuel gas having a high diffusion rate. In this case, a conventional separator can be used, and the cost can be reduced.

1 is a cross-sectional perspective view of a fuel cell according to the present invention. It is a figure explaining the detail of a separator. It is sectional drawing of the other example of a separator. It is a figure which shows the example of the cross section of a comb-tooth shaped flow path. It is a figure explaining the further another example of a separator.

Explanation of symbols

2 Electrolyte membrane 3, 3a Separator 4 Gas diffusion layer 5 Catalyst layer 6 Cooling medium flow path 10 Power generation cell 11 Gas supply flow path 11a Gas supply port 11b, 12b Comb-shaped flow path 11c Gas distribution flow path 12 Gas discharge flow path 12a Gas outlet 12c Gas recovery flow path 20 Single cell 100 Fuel cell

Claims (4)

A power generation cell having an electrolyte membrane;
A separator facing the power generation cell,
A groove-like gas supply passage for supplying fuel gas or oxidant gas to the power generation cell and a groove for collecting the fuel gas or oxidant gas after reaction from the power generation cell on the power generation cell side surface of the separator Gas-shaped gas discharge passages are formed in a comb shape that meshes with each other,
An opening width of the gas supply channel and the gas discharge channel is smaller than a maximum width of the gas supply channel and the gas discharge channel, respectively. The separator is made of a conductive plate,
The fuel cell according to claim 1, wherein the gas supply channel and the gas discharge channel are formed by pressing the conductive plate. The fuel cell according to claim 2, wherein the separator is a press metal. 4. The fuel cell according to claim 2, wherein the groove on the surface of the separator opposite to the power generation cell is a coolant flow path through which a coolant for cooling the fuel cell flows.

Images