JP2006278247A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to exhaust water surely from a reaction gas flow passage so that an excellent power generation performance can be secured by a simple and economical constitution. <P>SOLUTION: A fuel cell 10 is provided with first and second metal separators 14, 16 which pinch an electrolyte membrane/electrode structure 12. The first metal separator 14 is installed with an oxidizer gas flow passage 30 that is communicated with an oxidizer gas inlet communicating hole 24a and an oxidizer gas outlet communicating hole 24b, while on the wall face of the oxidizer gas flow passage 30, a plurality of projection parts 34 are integrally molded by press molding in order to obstruct formation of droplets of formed water. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte and a metal separator are laminated, and a reaction occurs along the electrode surface between the electrolyte / electrode structure and the metal separator. The present invention relates to a fuel cell in which a reaction gas flow path for supplying gas is formed.

  For example, a solid polymer fuel cell employs a solid polymer electrolyte membrane made of a polymer ion exchange membrane. This fuel cell has an electrolyte membrane / electrode structure in which an anode side electrode and a cathode side electrode each made of an electrode catalyst (electrode catalyst layer) and porous carbon (diffusion layer) are provided on both sides of a solid polymer electrolyte membrane. The power generation cell is sandwiched between separators (bipolar plates). Usually, a fuel cell is used as a fuel cell stack in which a predetermined number of power generation cells are stacked.

  In the fuel cell described above, an oxidant gas and a fuel gas, which are reaction gases, are supplied to the anode side electrode and the cathode side electrode, respectively. Therefore, a plurality of flow paths are provided between the electrolyte membrane / electrode structure and each separator. An oxidant gas channel and a fuel gas channel (reactive gas channel) having a groove are formed.

  By the way, in the oxidant gas flow path, the reaction product water generated at the time of power generation (reaction) may stay, and the stay water may exist. On the other hand, there is a possibility that stagnant water may be generated in the fuel gas flow path due to reverse diffusion or dew condensation of generated water. As a result, the oxidant gas flow path and the fuel gas flow path are easily reduced or blocked by the staying water, and freezing of the staying water is caused at a low temperature, and the flow of the oxidant gas and the fuel gas is hindered. There is a problem that decreases.

  Thus, for example, a fuel cell separator disclosed in Patent Document 1 and a manufacturing method thereof are known. In this prior art, a fuel cell separator is blasted to form irregularities on the gas flow path surface, and then a fluorine-containing gas plasma is irradiated to form a fluorine-containing carbon layer. Furthermore, by removing the fluorine-containing carbon layer other than the gas channel surface, a gas channel surface having a fluorine-containing carbon layer whose water-repellent effect is increased by unevenness is obtained.

JP2003-123780A (FIG. 1)

  However, in the above-described conventional technology, blasting, plasma irradiation, and removal of an unnecessary fluorine-containing carbon layer are performed, and there is a problem that the operation is complicated and time-consuming and is not efficient.

  The present invention solves this type of problem, and provides a fuel cell capable of reliably draining from a reaction gas flow path and capable of efficient power generation with a simple and economical configuration. For the purpose.

  In the present invention, an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte and a metal separator are laminated, and a reaction occurs along the electrode surface between the electrolyte / electrode structure and the metal separator. It is a fuel cell in which a reaction gas flow path for supplying gas is formed.

  The reaction gas channel has a plurality of channel grooves, and the wall surface forming the channel grooves is integrally formed with a deformed surface having a concave part, a convex part or an uneven part by press molding. .

  The electrolyte / electrode structure and the metal separator are stacked in the horizontal direction, and the deformation surfaces are preferably at least a groove bottom surface and a groove side surface that form a flow channel groove. Further, the deformation surface is preferably subjected to a roughening treatment, and the deformation surface is preferably subjected to a hydrophilic treatment.

  According to the present invention, a deformed surface having a concave shape portion, a convex shape portion, or an uneven shape portion is integrally formed by press molding on the wall surface of the flow channel groove that constitutes the reaction gas flow channel. For this reason, in the channel groove, the surface tension of water can be satisfactorily broken under the action of the deformed surface, preventing the formation of isolated water droplets, reducing the resistance to water movement, Reliable wastewater treatment can be performed.

  Moreover, the deformed surface has a function of reducing the drainage speed as compared with the flat surface. Therefore, water is continuously discharged from the reaction gas flow path toward the reaction gas outlet, and the water is not isolated and does not generate surface tension, so that the drainage can be easily improved.

  As a result, the reaction gas flow path is not clogged with stagnant water, and it is possible to reliably obtain a stable power generation voltage with a simple configuration and to cause freezing of stagnant water. In particular, the low temperature startability is improved satisfactorily.

  FIG. 1 is an exploded perspective view of a main part of a fuel cell 10 according to the first embodiment of the present invention, and FIG. 2 is a partial cross-sectional view of the fuel cell 10.

  The fuel cell 10 is formed by laminating an electrolyte membrane / electrode structure (electrolyte / electrode structure) 12 and first and second metal separators 14 and 16 in the horizontal direction (arrow A direction). Used as a battery stack. The first and second metal separators 14 and 16 are configured by subjecting a thin metal plate to a press molding process.

  The electrolyte membrane / electrode structure 12 includes, for example, a solid polymer electrolyte membrane 18 in which a thin film of perfluorosulfonic acid is impregnated with water, and a cathode side electrode 20 and an anode side electrode 22 that sandwich the solid polymer electrolyte membrane 18. With.

  The cathode side electrode 20 and the anode side electrode 22 are uniformly coated on the surface of the gas diffusion layer with a gas diffusion layer (not shown) made of carbon paper or the like and porous carbon particles carrying a platinum alloy supported on the surface. An electrode catalyst layer (not shown). The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 18.

  As shown in FIG. 1, an oxidant for supplying an oxidant gas, for example, an oxygen-containing gas, to one end edge of the fuel cell 10 in the direction of arrow B and communicating with each other in the direction of arrow A which is the stacking direction A gas inlet communication hole 24a and a fuel gas outlet communication hole 26b for discharging a fuel gas, for example, a hydrogen-containing gas, are arranged in an arrow C direction (vertical direction).

  The other end edge of the fuel cell 10 in the direction of arrow B communicates with each other in the direction of arrow A, a fuel gas inlet communication hole 26a for supplying fuel gas, and an oxidant gas for discharging oxidant gas. Outlet communication holes 24b are arranged in the direction of arrow C.

  Two cooling medium inlet communication holes 28a for supplying a cooling medium are provided at the lower end in the direction of arrow C of the fuel cell 10, and at the upper end of the fuel cell 10 in the direction of arrow C for discharging the cooling medium. Two cooling medium outlet communication holes 28b are provided.

  As shown in FIGS. 1 and 2, an oxidant gas flow path (reactive gas flow path) 30 is provided on the surface 14 a of the first metal separator 14 facing the electrolyte membrane / electrode structure 12. The oxidant gas flow path 30 has a plurality of oxidant gas flow path grooves 30a, and the oxidant gas flow path groove 30a constitutes a serpentine flow path that is folded back and forth by one reciprocal half in the direction of arrow B. In place of the serpentine channel, a substantially U-shaped curved channel or a linear channel directed in the direction of arrow B may be employed.

  As shown in FIGS. 1 and 3, an inlet buffer portion 32a having a plurality of embosses (or dimples) is provided between the oxidant gas flow path 30 and the oxidant gas inlet communication hole 24a. An outlet buffer portion 32b having a plurality of embosses (or dimples) is provided between the oxidant gas flow path 30 and the oxidant gas outlet communication hole 24b.

  As shown in FIGS. 2 and 3, a plurality of cylindrical protrusions (convex portions) 34 are integrally formed on the wall surface of the oxidant gas flow path 30 by press molding. Specifically, as shown in FIG. 2, at least the groove bottom surface 30a1 and the groove side surface 30a2 among the groove bottom surface 30a1, the groove side surface 30a2, and the groove upper surface 30a3 that form the wall surface of the oxidant gas flow channel groove 30a are A deformed surface having a plurality of protrusions 34 is formed by press molding.

  A plurality of protrusions 34 may be provided on the groove upper surface 30a3 as necessary. Similarly, a plurality of protrusions 34 may be provided on the inlet buffer portion 32a and the outlet buffer portion 32b. The protrusions 34 are provided with a diameter of 0.1 mm to 5 mm and separated from each other by 5 mm or less.

  It is preferable that at least the groove bottom surface 30a1 and the groove side surface 30a2 in which the protrusions 34 are integrally formed are roughened by polishing, etching, or the like. Furthermore, it is preferable that at least the groove bottom surface 30a1 and the groove side surface 30a2 are subjected to hydrophilic treatment.

  As the hydrophilic treatment, for example, by bringing a solution in which a hydrophilic substance is mixed in a liquid medium into contact with the groove bottom surface 30a1 and the groove side surface 30a2, or a hydrophilic coating film made of an organic compound or an inorganic compound, In addition to the formation of the groove bottom surface 30a1 and the groove side surface 30a2, various known methods are applied. The hydrophilicity is represented by a contact angle between the water droplet and the substance surface, and is set to a contact angle of 90 degrees or less, for example.

  As shown in FIG. 4, a fuel gas channel (reactive gas channel) 36 is provided on the surface 16 a of the second metal separator 16 facing the electrolyte membrane / electrode structure 12. Similar to the oxidant gas flow path 30, the fuel gas flow path 36 has a plurality of fuel gas flow path grooves 36 a that constitute a serpentine flow path that is folded back and forth in the direction of arrow B by one halfway.

  Between the fuel gas passage 36 and the fuel gas inlet communication hole 26a, an inlet buffer portion 38a having a plurality of embosses (or dimples) is provided. An outlet buffer portion 38b having a plurality of embosses (or dimples) is provided between the fuel gas flow path 36 and the fuel gas outlet communication hole 26b.

  A plurality of cylindrical protrusions (convex portions) 40 are integrally formed on the wall surface of the fuel gas flow path 36 by press molding. Specifically, as shown in FIG. 2, at least the groove bottom surface 36a1 and the groove side surface 36a2 of the groove bottom surface 36a1, the groove side surface 36a2, and the groove upper surface 36a3 that form the wall surface of the fuel gas flow channel groove 36a are pressed. A deformed surface having a plurality of protrusions 40 is formed by molding. The groove upper surface 36a3, the inlet buffer portion 38a, and the outlet buffer portion 38b may be provided with a plurality of protrusions 40 as necessary. The protrusion 40 is configured in the same manner as the protrusion 34 described above, and a detailed description thereof is omitted.

  As shown in FIGS. 1 and 2, the cooling medium that communicates the cooling medium inlet communication hole 28 a and the cooling medium outlet communication hole 28 b with the surface 14 b of the first metal separator 14 and the surface 16 b of the second metal separator 16. A flow path 42 is formed. The cooling medium channel 42 allows the cooling medium to flow vertically upward.

  A first seal member 44 is integrally formed on the surfaces 14 a and 14 b of the first metal separator 14 around the outer peripheral end of the first metal separator 14. A second seal member 46 is integrally formed on the surfaces 16 a and 16 b of the second metal separator 16 around the outer peripheral end of the second metal separator 16.

  The operation of the fuel cell 10 configured as described above will be described below.

  As shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 24a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 26a. Further, a cooling medium such as pure water or ethylene glycol is supplied to the cooling medium inlet communication hole 28a.

  The oxidant gas is introduced into the oxidant gas flow path 30 of the first metal separator 14 from the oxidant gas inlet communication hole 24a. In the oxidant gas flow channel 30, the oxidant gas is once introduced into the inlet buffer portion 32a and then dispersed in the plurality of oxidant gas flow channel grooves 30a. Therefore, the oxidant gas moves while meandering along the cathode side electrode 20 of the electrolyte membrane / electrode structure 12.

  On the other hand, the fuel gas is introduced into the fuel gas flow path 36 of the second metal separator 16 from the fuel gas inlet communication hole 26a. In the fuel gas channel 36, as shown in FIG. 4, the fuel gas is once introduced into the inlet buffer 38a and then dispersed in the plurality of fuel gas channel grooves 36a. As a result, the fuel gas moves while meandering along the anode electrode 22 of the electrolyte membrane / electrode structure 12.

  Therefore, in the electrolyte membrane / electrode structure 12, the oxidant gas supplied to the cathode side electrode 20 and the fuel gas supplied to the anode side electrode 22 are consumed by an electrochemical reaction in the electrode catalyst layer to generate power. Is done.

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 20 is discharged from the outlet buffer portion 32b to the oxidant gas outlet communication hole 24b (see FIG. 1) and is also supplied to the anode side electrode 22 and consumed. The fuel gas thus discharged is discharged from the outlet buffer portion 38b to the fuel gas outlet communication hole 26b (see FIG. 4).

  On the other hand, the cooling medium supplied to the cooling medium inlet communication hole 28a is introduced into the cooling medium flow path 42 formed between the first and second metal separators 14 and 16 (see FIG. 1). In the cooling medium flow path 42, the cooling medium moves vertically upward. Therefore, the cooling medium is cooled over the entire electrode surface of the electrolyte membrane / electrode structure 12 and then discharged to the cooling medium outlet communication hole 28b.

  In this case, in the first embodiment, for example, on the surface 14a of the first metal separator 14, a plurality of protrusions 34 are integrally formed on the wall surface of the oxidant gas flow path 30 by press molding. For this reason, the surface tension of the water generated along each oxidant gas flow channel groove 30 a constituting the oxidant gas flow channel 30 during power generation (reaction) is destroyed via the protrusions 34. Therefore, in the oxidant gas flow channel groove 30a, it is possible to prevent the formation of isolated water droplets, and it is possible to reduce the movement resistance of water and to perform smooth and reliable drainage treatment. It is done.

  Moreover, in the groove bottom surface 30a1 and the groove side surface 30a2, which are deformed surfaces on which the plurality of protrusions 34 are provided, the drainage rate can be reduced compared to the flat surface. As a result, water is continuously discharged from the oxidant gas channel groove 30a toward the oxidant gas outlet communication hole 24b, and the water is not isolated and does not generate surface tension, thereby improving drainage. Easy to carry out.

  Further, the oxidant gas flow channel groove 30a has an advantage that drainage is more reliably performed by configuring the groove bottom surface 30a1 and the groove side surface 30a2 that are particularly likely to generate stagnant water as deformed surfaces.

  Furthermore, the groove bottom surface 30a1 and the groove side surface 30a2 are subjected to a roughening process, and it becomes possible to more reliably prevent the generation of water droplets. Further, the groove bottom surface 30a1 and the groove side surface 30a2 are subjected to hydrophilic treatment to prevent the formation of water droplets, and a continuous flow of water is caused to improve drainage more easily.

  As a result, in the first embodiment, the oxidant gas flow path 30 is not clogged with stagnant water, and a stable power generation voltage can be reliably obtained with a simple configuration. It is possible to prevent the water from freezing and improve the cold startability.

  Further, by providing a plurality of protrusions 34 projecting toward the oxidant gas flow channel groove 30a, turbulence is induced in the oxidant gas flowing through the oxidant gas flow channel groove 30a, and the electrolyte membrane / electrode structure The supply of the oxidant gas to the body 12 is favorably performed. On the other hand, in the cooling medium flow path 42, a large number of concave-shaped portions are provided on the surface 14b side corresponding to the back side of the protrusions 34, so that the surface area is increased and the cooling efficiency of the first metal separator 14 is more effectively improved. There is an advantage that

  Similarly, the fuel gas flow path 36 is provided with a plurality of protrusions 40, and the same effect as that of the oxidant gas flow path 30 described above can be obtained.

  FIG. 5 is an explanatory front view of the first metal separator 50 constituting the fuel cell according to the second embodiment of the present invention. In addition, the same referential mark is attached | subjected to the component same as the 1st metal separator 14 which comprises the fuel cell 10 which concerns on 1st Embodiment, and the detailed description is abbreviate | omitted. Similarly, in the third embodiment described below, detailed description thereof is omitted.

  A plurality of cylindrical protrusions (convex portions) 52 are integrally formed in the oxidant gas flow path 30 by press molding. The protrusion 52 is provided so as to become denser from the upstream end 54 a to the downstream end 54 b of the oxidant gas flow path 30. In particular, a large number of protrusions 52 are provided at the downstream end 54b where a large amount of water is likely to be generated.

  Thus, in the second embodiment, the arrangement of the protrusions 52 is set roughly according to the amount of generated water in the oxidant gas flow path 30. For this reason, the effect that the generated water can be reliably discharged to the oxidant gas outlet communication hole 24b while maintaining a smooth flow of the oxidant gas is obtained.

  FIG. 6 is an explanatory front view of the first metal separator 60 constituting the fuel cell according to the third embodiment of the present invention.

  In the first metal separator 60, a plurality of cylindrical protrusions (convex portions) 62 are integrally formed in the oxidant gas flow path 30 by press molding. The oxidant gas flow path 30 includes an upstream portion 64a, a midstream portion 64b, and a downstream portion 64c. The upstream portion 64a is roughly arranged with a protrusion 62, while the downstream portion 64c includes the protrusion. 62 is densely arranged, and is arranged in the middle flow portion 64b in an intermediate density state.

  Therefore, in the third embodiment, the provision of the large number of protrusions 62 in the downstream portion 64c where the generated water is most likely to be generated in a large amount provides an effect of easily improving drainage.

  In the first to third embodiments described above, the cylindrical protrusions 34, 52 and 62 are provided in the oxidant gas flow path 30, but the present invention is not limited to this. For example, as shown in FIGS. 7 and 8, a substantially arcuate protrusion 80 may be employed. Moreover, as shown in FIG.9 and FIG.10, you may employ | adopt the some convex-shaped part 100 set to rectangular shape by planar view. For example, the convex portions 100 are arranged in pairs so that the longitudinal directions intersect each other.

  A groove 102 is provided between the convex portions 100, and the surface tension of water can be destroyed by moving the water along the groove 102. Furthermore, by setting the groove width of the groove portion 102, it is possible to prevent the water flow from becoming excessively fast and causing water droplets to remain due to water separation.

  Furthermore, as shown in FIG. 11, a plurality of convex portions 104 that are rectangular in plan view may be employed. The convex portions 104 are arranged such that the respective longitudinal directions are directed in the same direction, and the groove portions 106 are continuously provided between the convex portions 104.

  Furthermore, although not shown in the drawing, the same effect can be obtained even if various shapes such as a cylindrical or rectangular concave portion or concave and convex portion are employed.

It is a principal part disassembled perspective view of the fuel cell which concerns on the 1st Embodiment of this invention. 2 is a partial cross-sectional view of the fuel cell. FIG. It is front explanatory drawing of the 1st metal separator which comprises the said fuel cell. It is front explanatory drawing of the 2nd metal separator which comprises the said fuel cell. It is front explanatory drawing of the 1st metal separator which comprises the fuel cell which concerns on the 2nd Embodiment of this invention. It is front explanatory drawing of the 1st metal separator which comprises the fuel cell which concerns on the 3rd Embodiment of this invention. It is explanatory drawing of a substantially circular arc-shaped projection part. FIG. 8 is a sectional view taken along line VIII-VIII in FIG. It is explanatory drawing of a convex-shaped part. FIG. 10 is a sectional view taken along line XX in FIG. 9. It is explanatory drawing of another convex-shaped part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12 ... Electrolyte membrane and electrode structure 14, 16, 50, 60 ... Metal separator 18 ... Solid polymer electrolyte membrane 20 ... Cathode side electrode 22 ... Anode side electrode 24a ... Oxidant gas inlet communication hole 24b ... Oxidation Agent gas outlet communication hole 26a ... Fuel gas inlet communication hole 26b ... Fuel gas outlet communication hole 28a ... Cooling medium inlet communication hole 28b ... Cooling medium outlet communication hole 30 ... Oxidant gas channel 30a ... Oxidant gas channel groove 30a1, 36a1 ... groove bottom surface 30a2, 36a2 ... groove side surface 30a3, 36a3 ... groove top surface 32a, 38a ... inlet buffer part 32b, 38b ... outlet buffer part 34, 40, 52, 62 ... projection part 36 ... fuel gas flow path 36a ... fuel gas Channel groove 42 ... Cooling medium channel 80 ... Substantially arcuate projections 100, 104 ... Convex part

Claims (4)

An electrolyte / electrode structure provided with a pair of electrodes on both sides of the electrolyte and a metal separator are laminated, and a reactive gas is supplied along the electrode surface between the electrolyte / electrode structure and the metal separator. A fuel cell in which a reaction gas flow path is formed,
The reactive gas channel has a plurality of channel grooves, and a deformed surface having a concave part, a convex part, or a concave and convex part is integrally formed by press molding on the wall surface forming the channel groove. The fuel cell characterized by the above-mentioned. The fuel cell according to claim 1, wherein the electrolyte / electrode structure and the metal separator are stacked in a horizontal direction,
The fuel cell according to claim 1, wherein the deformation surface is at least a groove bottom surface and a groove side surface forming the flow channel groove.   3. The fuel cell according to claim 1, wherein the deformation surface is subjected to a roughening process.   4. The fuel cell according to claim 1, wherein the deformed surface is subjected to a hydrophilic treatment.

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