JP2009021140A - Separator for fuel cell and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator for a fuel cell and the fuel cell capable of detecting the end of life of a corrosion-resistant layer suppressing corrosion of a metallic base material, before the metallic base material corrodes. <P>SOLUTION: This separator for the fuel cell has the metallic base material, an intermediate layer formed on the metallic base material and composed of metal having corrosion resisting property lower than that of the metallic base material, and the corrosion-resisting layer formed on the intermediate layer and composed of metal or resin having corrosion resisting property higher than that of the metallic base material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell separator and a fuel cell technology.

  Generally, a fuel cell has a membrane-electrode assembly including a pair of electrodes (anode electrode and cathode electrode) sandwiching both sides of an electrolyte membrane, and a pair of fuel cell separators sandwiching both sides of the membrane-electrode assembly. . The anode electrode has an anode electrode catalyst layer and a diffusion layer, and the cathode electrode has a cathode electrode catalyst layer and a diffusion layer. At the time of power generation of the fuel cell, when the anode gas supplied to the anode electrode is hydrogen gas, and the cathode gas supplied to the cathode electrode is oxygen gas, a reaction to form hydrogen ions and electrons is performed on the anode electrode side. The electrons reach the cathode electrode through an external circuit through the electrolyte membrane to the cathode electrode side. On the other hand, on the cathode side, hydrogen ions, electrons, and oxygen gas react to generate moisture, and energy is released.

  Examples of the fuel cell separator include those based on carbon and those based on metal.

  A fuel cell separator using a metal as a base material is superior in mechanical strength and formability as compared with a fuel cell separator using a carbon base material, but is easily corroded. When the separator for a fuel cell using a metal as a substrate corrodes, the elution component eluted from the metal substrate may cause deterioration of the performance of the fuel cell due to deterioration of the electrolyte membrane, contamination with the membrane-electrode assembly, or the like.

  For example, Patent Document 1 discloses a noble metal coat layer composed of a noble metal on a metal substrate and a carbon coat layer composed of a carbon material on the noble metal coat layer in order to suppress corrosion of the metal substrate. A fuel cell separator has been proposed.

  Further, for example, in Patent Document 2, in order to suppress corrosion of a metal base material, a first coating layer composed of a metal-based conductive paint on the metal base material and a graphite-based conductive material on the first coating layer. A fuel cell separator having a second coating layer composed of a conductive paint has been proposed.

  A corrosion-resistant layer (for example, a noble metal coat layer) for suppressing the corrosion of the metal substrate hardly corrodes even when it comes into contact with water generated during power generation of the fuel cell.

  However, since the corrosion-resistant layer is generally formed by plating, vapor deposition, or the like, it is difficult to form a pinholeless corrosion-resistant layer. The metal base material may be corroded by penetrating into the metal (passing through a pinhole or the like).

  Conventionally, the lifetime of the corrosion-resistant layer as described above is detected by detecting an elution component that elutes from the metal substrate, but when it is detected, the elution component is already eluted from the metal substrate, Deterioration of the electrolyte membrane, contamination of the membrane-electrode assembly, etc. may occur.

JP 2007-18781 A JP 2006-179242 A JP 2005-302304 A JP 2004-172105 A

  The present invention is a fuel cell separator and a fuel cell that can detect the life of a corrosion-resistant layer that suppresses corrosion of a metal substrate before the metal substrate corrodes.

  The separator for a fuel cell of the present invention has a metal base, an intermediate layer composed of a metal having a lower corrosion resistance than the metal base on the metal base, and a higher corrosion resistance than the metal base on the intermediate layer. And a corrosion-resistant layer made of metal or resin.

  In the fuel cell separator, it is preferable that the intermediate layer is made of a metal that does not become a contaminant component even if eluted.

  Further, in the fuel cell separator, the intermediate layer has a lower potential of the corroded area lower than the metal base or the pH of the corroded area is on the acidic side in the stable region of water in the potential-pH diagram. Is preferred.

  Further, the present invention is a fuel cell including a fuel cell separator, wherein the fuel cell separator is an intermediate composed of a metal base material and a metal having a lower corrosion resistance than the metal base material on the metal base material. And a corrosion-resistant layer composed of a metal or a resin having higher corrosion resistance than the metal base material on the intermediate layer.

  Moreover, it is preferable that the fuel cell further includes detection means for detecting a state of water generated during power generation of the fuel cell.

  According to the present invention, a metal base, an intermediate layer composed of a metal having lower corrosion resistance than the metal base on the metal base, and a metal or resin having higher corrosion resistance than the metal base on the intermediate layer By having a corrosion-resistant layer, it is possible to provide a fuel cell separator and a fuel cell that can detect the life of the corrosion-resistant layer before the metal substrate corrodes.

  Embodiments of the present invention will be described below.

  FIG. 1 is a schematic diagram showing an example of the configuration of a fuel cell according to an embodiment of the present invention. As shown in FIG. 1, the fuel cell 1 includes a membrane-electrode assembly 16 in which both sides of an electrolyte membrane 10 are sandwiched between an anode 12 and a cathode 14, and a fuel cell separator that sandwiches both outer sides of the membrane-electrode assembly 16. 18. Further, the fuel cell according to the present embodiment may be a stack of a plurality of fuel cells 1 as unit cells.

  The anode electrode 12 and the cathode electrode 14 each have a catalyst layer 20 and a diffusion layer 22.

  The catalyst layer 20 is formed, for example, by mixing carbon carrying a metal catalyst such as platinum or ruthenium with a perfluorosulfonic acid electrolyte or the like and forming the mixture on the diffusion layer 22 or the electrolyte membrane 10. The diffusion layer 22 is made of a porous material such as carbon cloth. The electrolyte membrane 10 is a membrane having proton conductivity. For example, a perfluorosulfonic acid resin membrane or the like is used.

  The fuel cell separator according to this embodiment will be described.

  FIG. 2A is a schematic plan view showing an example of the configuration of one surface of the fuel cell separator according to the present embodiment, and FIG. 2B is the other side of the fuel cell separator according to the present embodiment. It is a schematic plan view which shows an example of a structure of this surface. 2A and 2B, the fuel cell separator 18 is provided with anode gas manifolds 24a and 24b and cathode gas manifolds 26a and 26b. Further, as shown in FIG. 2 (a), the rib 30 forming the anode gas flow path 28 is formed on one surface of the fuel cell separator 18, and the other surface is formed on the other surface as shown in FIG. 2 (b). Ribs 30 forming the cathode gas flow path 32 are provided. In the present embodiment, the gas flow path (the anode gas flow path 28 and the cathode gas flow path 32) is formed on both surfaces of the fuel cell separator 18, but the present invention is not necessarily limited thereto. The structure by which the gas flow path was formed only in the surface may be sufficient.

  The anode gas manifold 24 a is an inlet for supplying the anode gas supplied into the fuel cell 1 to the anode gas flow path 28, and the anode gas manifold 24 b is for discharging the anode gas from the anode gas flow path 28. It is an exit. The cathode gas manifold 26 a is an inlet for supplying the cathode gas supplied into the fuel cell 1 to the cathode gas flow path 32, and the cathode gas manifold 26 b is for discharging the cathode gas from the cathode gas flow path 32. It is an exit.

  The operation of the fuel cell will be described with reference to FIGS.

  In the power generation of the fuel cell 1 shown in FIG. 1, on the anode electrode 12 side, the anode gas is supplied from the anode gas manifold 24a of the fuel cell separator 18 shown in FIG. The supplied anode gas passes through the anode gas flow path 28, is supplied to the anode electrode 12 (diffusion layer 22, catalyst layer 20) shown in FIG. 1, and is used for power generation. The anode gas used for power generation is discharged out of the fuel cell 1 through the anode gas manifold 24b of the fuel cell separator 18 shown in FIG. On the other hand, on the cathode electrode 14 side, the cathode gas is supplied from the cathode gas manifold 26a of the fuel cell separator 18 shown in FIG. The supplied cathode gas passes through the cathode gas flow path 32, is supplied to the cathode electrode 14 (diffusion layer 22, catalyst layer 20) shown in FIG. 1, and is used for power generation. The cathode gas used for power generation is discharged out of the fuel cell 1 through the cathode gas manifold 26b of the fuel cell separator 18 shown in FIG.

  As described above, water is generated by the power generation of the fuel cell 1. The produced water passes from the membrane-electrode assembly 16 through the reaction gas flow path (the anode gas flow path 28 and the cathode gas flow path 32) of the fuel cell separator 18 shown in FIGS. Water is drained out of the fuel cell 1 from the manifolds (anode gas manifolds 24a and 24b, cathode gas manifolds 26a and 26b). In particular, the reaction gas (anode gas, cathode gas) described above is discharged out of the fuel cell 1 from the manifold (anode gas manifold 24b, cathode gas manifold 26b) from which the reaction gas is discharged.

  FIG. 3 is a partially enlarged schematic cross-sectional view showing an example of the configuration of the fuel cell separator according to the present embodiment. As shown in FIG. 3, the fuel cell separator 18 includes a metal substrate 34, an intermediate layer 36 formed on the metal substrate 34, and a corrosion-resistant layer 38 formed on the intermediate layer 36.

  Since the corrosion-resistant layer 38 mainly suppresses corrosion of the metal substrate 34, the corrosion-resistant layer 38 is made of a metal or resin having higher corrosion resistance than the metal substrate 34. The intermediate layer 36 is mainly composed of a metal having a lower corrosion resistance than the metal base material 34 because the metal base material 34 corrodes before the metal base material 34 corrodes due to the life of the corrosion-resistant layer 38.

  In the present embodiment, as shown in FIG. 3, the configuration in which the intermediate layer 36 and the corrosion-resistant layer 38 are formed on both surfaces of the metal base material 34 is taken as an example, but the present invention is not necessarily limited thereto. As described above, when the reaction gas channel (the anode gas channel 28 or the cathode gas channel 32) is formed only on one surface of the fuel cell separator 18, the reaction gas channel is formed. An intermediate layer 36 and a corrosion-resistant layer 38 may be formed on the surface of the metal substrate 34 on the side. Further, on the metal substrate 34 in the rib 30, the reaction gas flow path (the anode gas flow path 28, the cathode gas flow path 32), the outer peripheral portion 40, and the manifold (the anode gas manifolds 24a and 24b and the cathode gas manifolds 26a and 26b). It is not necessary to form the intermediate layer 36 in all cases, and the intermediate layer 36 may be formed on the metal substrate 34 where corrosion is likely to occur. Examples of the portion that is easily corroded include the metal substrate 34 in the manifold (24b, 26b) serving as the outlet for discharging the reaction gas, and the metal substrate 34 in the peripheral portion 40 in the periphery thereof.

  The metal substrate 34 is not particularly limited as long as it is a known metal substrate used for the fuel cell separator 18, but preferably has strength resistance, corrosion resistance, and the like. Examples of the material constituting the metal substrate 34 include stainless steel, copper and copper alloys, titanium and titanium alloys, nickel-based substrates, aluminum and aluminum alloys, magnesium alloys, and iron. The metal base 34 is formed with the above-described reaction gas passages (anode gas passage 28 and cathode gas passage 32) by press molding or the like, and the manifolds (anode gas manifolds 24a and 24b) described above by punching or the like. Cathode gas manifolds 26a, 26b) are formed.

The intermediate layer 36 is made of a metal that has lower corrosion resistance than the metal substrate 34. The corrosion resistance of the metal substrate 34 and the intermediate layer 36 can be evaluated as follows. For example, the metal plate constituting the metal substrate 34 is immersed in sulfuric acid at pH 2 and 80 ° C. for 24 hours, and the amount of metal ions eluted in the sulfuric acid (μmol / cm ² · day) is measured. The amount of metal ions eluted in sulfuric acid is also measured under the same conditions for the metal plate constituting the intermediate layer 36. A metal ion with a higher elution amount is a metal with lower corrosion resistance. The amount of metal ions eluted in sulfuric acid can be detected by an ICP emission spectroscopic analyzer. Moreover, corrosion resistance can also be evaluated by LSV (Liner Sweep Voltammogram) which is an electrochemical evaluation method. Specifically, when the load potential is swept while measuring the corrosion current at the applied potential, the corrosion resistance of the material is represented by the integral value of the corrosion current curve, and the measurement curve is at the lower right. It can be evaluated that the corrosion resistance is high.

  For example, when titanium (Ti) is used for the metal substrate 34, the intermediate layer 36 is made of a metal having a lower corrosion resistance than Ti, for example, silver (Ag), copper (Cu), tin (Sn), nickel (Ni), iron (Fe), chromium (Cr), zinc (Zn), aluminum (Al), molybdenum (Mo), cerium (Ce), magnesium (Mg), zirconium (Zr), bismuth (Bi), manganese (Mn), cobalt (Co), thallium (Tl), or the like. Further, when copper (Cu) is used for the metal substrate 34, the intermediate layer 36 is made of a metal having lower corrosion resistance than Cu, for example, Sn, Ni, Fe, Cr, Zn, Al, Ce, Mg, Mn, Zr, etc. Composed.

  For example, when an alloy such as stainless steel, a copper alloy, or a titanium alloy is used for the metal substrate 34, the corrosion resistance varies depending on the composition of the alloy, so the metal constituting the intermediate layer 36 is selected depending on the composition of the alloy.

  For example, the stainless steel used for the metal substrate 34 includes austenitic stainless steel (iron-chromium-nickel alloy), ferritic stainless steel (iron-chromium alloy), martensitic stainless steel (iron-chromium alloy), and the like. is there. Among the above stainless steels, when an austenitic stainless steel having high corrosion resistance is used, the intermediate layer 36 is made of a metal having a lower corrosion resistance than austenitic stainless steel, such as Ag, Cu, Sn, Ni, Fe, Cr, Zn, Al, Zr. , Ce and the like. Further, when using ferritic stainless steel and martensitic stainless steel that are inferior in corrosion resistance to austenitic stainless steel, the intermediate layer 36 is made of a metal having lower corrosion resistance than ferritic stainless steel and martensitic stainless steel, such as Sn, Ni. , Fe, Cr, Zn, Al, Mg, Mn, Zr, Ce and the like.

  The metal constituting the intermediate layer 36 is not necessarily a single metal, and may be an alloy as long as the corrosion resistance is lower than that of the metal substrate 34.

  The intermediate layer 36 is preferably made of a metal having lower corrosion resistance than the metal substrate 34, and the metal does not become a contaminant component even when it comes into contact with water generated by the power generation of the fuel cell 1. In the case where the intermediate layer 36 is provided in the reaction gas flow path (the anode gas flow path 28, the cathode gas flow path 32), the rib 30, and the like, the eluted component eluted from the metal of the intermediate layer 36 contacts the electrolyte membrane 10 or the like. There are many opportunities to do. Therefore, the intermediate layer 36 is preferably made of a metal that does not elute contaminant components. On the other hand, when the intermediate layer 36 is provided in the vicinity of the reaction gas outlet manifold (24b, 26b), even if the elution component eluted from the metal of the intermediate layer 36 is a contamination component, the electrolyte membrane or the like is hardly used. Does not affect.

  Metals that do not become a contaminant component even when they come into contact with water generated by power generation of the fuel cell 1 are Mg, Zn, Ni, Cu, Al, Ti, Co, Mn, La, Ce, and the like.

  The intermediate layer 36 is preferably made of a metal having a larger corrosion area than the metal substrate 34 in the stable region of water in the potential-pH diagram.

  FIG. 4A is an example of a potential-pH diagram showing a stable region of water, and FIG. 4B is a diagram for explaining a potential-pH diagram of a metal. The potential-pH diagram represents the state of the metal material in environments with different pH and potential. As shown in FIG. 4 (b), the metal causes a corrosion region that is energetically stabilized by corrosion, a passive region that is energetically stabilized by passive formation, and a reaction due to changes in potential and pH. There is a stable region in which no state is energetically stable. Depending on the type of metal, the corrosion region, passive region, and stable region shown in FIG.

  The stable region of water shown in FIG. 4 (between pH 0 and 14, the upper limit of the potential is 1.2 V to 0.4 V (vs. SHE) and the lower limit is 0 V to −0.8 V (vs. SHE)) Is a region where water exists stably. Outside the stable region, water is decomposed to generate oxygen and hydrogen.

  The pH of water generated by the power generation of the fuel cell 1 may also fluctuate to the acidic side due to deterioration of the members constituting the fuel cell 1 or the like. That is, the environment during power generation of the fuel cell 1 is included in the stable region of water shown in FIG. Accordingly, in the stable region of water in the potential-pH diagram shown in FIG. 4, which metal in the internal environment of the fuel cell 1 depends on whether each metal belongs to one of the corrosion region, the passive region, or the stable region. You can see how it is affected.

  Since the intermediate layer 36 needs to corrode in the internal environment of the fuel cell 1, the intermediate layer 36 has a corroded region in the stable region of water in the potential-pH diagram, and the lower limit potential of the corroded region is lower than that of the metal substrate 34. It is preferable that the pH of the corrosion region is on the acidic side.

  The thickness of the intermediate layer 36 is not particularly limited as long as it can be formed as a layer and does not adversely affect the battery performance. For example, it may be in the range of 0.01 to 10 μm. preferable. If the thickness of the intermediate layer 36 is less than 0.01 μm, formation as a layer becomes difficult and the metal substrate 34 may not be covered. On the other hand, when the film thickness of the intermediate layer 36 is thicker than 10 μm, the contact resistance of the fuel cell separator 18 may be increased, and peeling may occur.

  The formation of the intermediate layer 36 is not particularly limited, such as a known electrolytic plating method, electroless plating method, sputtering method, plasma CVD method, ion plating method, ink jet method, etc. The intermediate layer 36 may be formed by a vapor deposition method such as a sputtering method, a plasma CVD method, an ion plating method, and an ink jet method in terms of weakening the bonding force and facilitating the elution (easy to corrode) of the metal component. preferable.

  The corrosion resistant layer 38 is made of a metal or resin having higher corrosion resistance than the metal substrate 34. For example, when Cu or Ti is used for the metal substrate 34, the corrosion-resistant layer 38 is made of a metal having higher corrosion resistance than the metal substrate 34, such as gold (Au), platinum (Pt), ruthenium (Ru), tantalum (Ta ), Niobium (Nb), and the like. Further, when the above-described stainless steel, copper alloy, titanium alloy, or the like is used, the corrosion resistance varies depending on the composition of the alloy. Therefore, the metal constituting the corrosion-resistant layer 38 is selected depending on the composition of the alloy. The evaluation of the corrosion resistance is as described above.

  For example, when austenitic stainless steel (iron-chromium-nickel alloy) having strong corrosion resistance is used as the metal base material 34 among stainless steels, the corrosion resistant layer 38 is made of a metal having higher corrosion resistance than austenitic stainless steel, for example, Au, Pt. , Ru, Ta, Nb, etc. When ferritic stainless steel (iron-chromium alloy), martensitic stainless steel (iron-chromium alloy) or the like is used for the metal substrate 34, the corrosion-resistant layer 38 is made of ferritic stainless steel (iron-chromium alloy), It is made of a metal having higher corrosion resistance than martensitic stainless steel (iron-chromium alloy), such as Au, Pt, Ru, Ta, Nb, and Ti.

  The resin constituting the corrosion-resistant layer 38 is not particularly limited as long as it has higher corrosion resistance than the metal substrate 34. For example, a polyolefin-based resin such as polyethylene or polypropylene, or a polyester-based resin such as polyethylene terephthalate or polypropylene terephthalate. Resins, polystyrene resins, polyimide resins, polyacrylonitrile resins, polyurethane resins, cellulose resins, rubbers such as SBR, phenol resins, acrylic resins, epoxy resins, polyethylene dioxythiolenes, polyamines, polypyrroles, and other resins It is done. Further, carbon or the like is added to the resin in order to make the corrosion resistant layer 38 conductive. The comparison of the corrosion resistance between the metal and the resin is the same as above. That is, the resin plate constituting the corrosion-resistant layer 38 is immersed in sulfuric acid having a pH of 2, for example, 80 ° C. for 24 hours, and the amount of resin eluted in the sulfuric acid (μmol / cm 2 · day) is measured. The metal plate constituting the metal substrate 34 is also performed in the same manner as described above. And the one where there is much elution amount is a metal with low corrosion resistance. The amount of resin eluted in sulfuric acid can be detected by an ICP emission spectroscopic analyzer. Moreover, corrosion resistance can also be evaluated by LSV (Liner Sweep Voltammogram) which is an electrochemical evaluation method. Specifically, when the load potential is swept while measuring the corrosion current at the applied potential, the corrosion resistance of the material is represented by the integral value of the corrosion current curve, and the measurement curve is at the lower right. It can be evaluated that the corrosion resistance is high.

  As described above, the corrosion-resistant layer 38 is mainly for suppressing the corrosion of the metal substrate 34. Therefore, the corrosion-resistant layer 38 has a corrosion region in the stable region of water in the potential-pH diagram shown in FIG. Preferably, it is made of no metal. Examples of such metals include gold (Au), platinum (Pt), iridium (Ir), rhodium (Rh), ruthenium (Ru), tantalum (Ta), niobium (Nb), and the like. Further, the metal does not have to have a corrosion region at all in the stable region of water, and the metal may have an area of the corrosion region within 10% in the stable region of water.

  The thickness of the corrosion-resistant layer 38 is not particularly limited as long as the corrosion of the metal substrate 34 can be suppressed, but is preferably 0.01 μm or more, for example. When the film thickness of the corrosion-resistant layer 38 is thinner than 0.01 μm, there are many pinholes, and corrosion of the metal base material 34 may not be suppressed.

  The formation of the corrosion-resistant layer 38 made of metal is not particularly limited, such as a known electrolytic plating method, electroless plating method, sputtering method, plasma CVD method, ion plating method, and ink jet method. It is preferable that the corrosion-resistant layer is formed by an electrolytic plating method or an electroless plating method from the viewpoint that the bonding strength of the metal constituting the metal can be increased and the corrosion resistance can be improved. The formation of the corrosion-resistant layer 38 made of resin is not particularly limited, such as dipping, spraying, brushing or the like.

  As described above, the fuel cell according to the present embodiment includes an intermediate layer composed of a metal having a lower corrosion resistance than the metal substrate on the metal substrate, and a metal or resin having a higher corrosion resistance than the metal substrate on the intermediate layer. By having the corrosion resistant layer configured, the intermediate layer is more easily corroded than the metal base material, so that the life of the corrosion resistant layer can be detected before the metal base material corrodes. If the metal constituting the intermediate layer elutes due to the life of the corrosion-resistant layer, the conductivity of the water drained from the fuel cell will increase, the pH will move to the acidic side, the color will change, and so on. Thus, the lifetime of the corrosion-resistant layer can be detected by examining the conductivity and the like.

  Next, a fuel cell according to another embodiment of the present invention will be described.

  FIG. 5 is a schematic diagram showing an example of the configuration of a fuel cell according to another embodiment of the present invention. As shown in FIG. 5, the fuel cell 2 includes a plurality of unit cells 40 and a conductivity detector 42. In the present embodiment, the number of unit cells 40 is not particularly limited. The unit cell 40 has the same configuration as the fuel cell 1 shown in FIG. 1. Although not shown, the unit cell 40 includes a membrane-electrode assembly in which both sides of the electrolyte membrane are sandwiched between an anode electrode and a cathode electrode, and a membrane-electrode assembly. And a fuel cell separator sandwiching both outer sides.

  The conductivity detector 42 detects the conductivity of water generated when the fuel cell 2 generates power. As described above, when water generated during power generation of the fuel cell 2 penetrates into the corrosion-resistant layer of the fuel cell separator and contacts the intermediate layer, the metal component is eluted from the intermediate layer. Sometimes the conductivity of the water produced is increased. That is, when the conductivity detector 42 detects the conductivity of water generated during power generation of the fuel cell 2 and exceeds a predetermined conductivity set in the conductivity detector 42, the corrosion resistant layer of the fuel cell separator It can be determined that the lifetime is.

  In the present embodiment, the detection unit is not necessarily limited to the conductivity detector 42 as long as the detection unit can detect the state of water generated during power generation of the fuel cell 2. For example, when the metal component is eluted from the intermediate layer, the pH of water generated during power generation of the fuel cell 2 may move to the acidic side. Therefore, a pH detector that can detect the pH of water generated during power generation of the fuel cell 2 may be used. Further, when the color of water generated during power generation of the fuel cell changes due to the elution of the metal component from the intermediate layer, an image sensor may be used. Detection may be performed by changing the potential of the ion electrode that reacts with a specific ion species. In accordance with the metal constituting the intermediate layer, the state of water generated during power generation of the fuel cell 2 varies depending on the metal constituting the intermediate layer, and therefore it is possible to select a detection means suitable for detecting the changed water state. preferable.

  As described above, the fuel cell of the present embodiment is configured by an intermediate layer made of a metal having a lower corrosion resistance than the metal substrate on the metal substrate, and a metal or resin having a higher corrosion resistance than the metal substrate on the intermediate layer. By providing a separator for a fuel cell having a corrosion resistant layer and a detecting means capable of detecting the state of water generated during power generation of the fuel cell, the life of the corrosion resistant layer is detected before the metal substrate corrodes. It becomes possible to do.

  The fuel cell according to the present embodiment can be used as, for example, a small power source for mobile devices such as a mobile phone and a portable personal computer, a power source for automobiles, a household power source, and the like.

It is a schematic diagram which shows an example of a structure of the fuel cell which concerns on embodiment of this invention. It is a schematic plan view which shows an example of the structure of one surface and the other surface of the separator for fuel cells which concerns on this embodiment. It is a partially expanded schematic sectional view which shows an example of a structure of the separator for fuel cells which concerns on this embodiment. (A) is an example of a potential-pH diagram showing a stable region of water, and (B) is a diagram for explaining a potential-pH diagram of a metal. It is a schematic diagram which shows an example of a structure of the fuel cell which concerns on other embodiment of this invention.

Explanation of symbols

  1, 2 Fuel cell, 10 Electrolyte membrane, 12 Anode electrode, 14 Cathode electrode, 16 Membrane-electrode assembly, 18 Fuel cell separator, 20 Catalyst layer, 22 Diffusion layer, 24a, 24b Anode gas manifold, 26a, 26b Cathode gas Manifold, 28 Anode gas flow path, 30 Rib, 32 Cathode gas flow path, 34 Metal substrate, 36 Intermediate layer, 38 Corrosion resistant layer, 40 Outer periphery, 40 Unit cell, 42 Conductivity detector.

Claims (5)

A metal substrate;
An intermediate layer composed of a metal having a lower corrosion resistance than the metal substrate on the metal substrate;
A fuel cell separator having a corrosion resistant layer made of a metal or a resin having higher corrosion resistance than the metal base material on the intermediate layer.   2. The fuel cell separator according to claim 1, wherein the intermediate layer is made of a metal that does not become a contaminant component even if eluted. 3.   3. The fuel cell separator according to claim 2, wherein the intermediate layer has a lower lower limit potential of the corroded region or a pH of the corroded region in the stable region of water in the potential-pH diagram than the metal substrate. Is on the acidic side, a fuel cell separator. A fuel cell including a fuel cell separator,
The fuel cell separator includes a metal base, an intermediate layer formed of a metal having lower corrosion resistance than the metal base on the metal base, and a metal having higher corrosion resistance than the metal base on the intermediate layer, or A fuel cell comprising a corrosion-resistant layer made of a resin.   5. The fuel cell according to claim 4, further comprising detection means for detecting a state of water generated during power generation of the fuel cell.

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