Power generation element

Abstract

To provide a power generation element which can reduce energy consumption or attached items.SOLUTION: The power generation element has a cell including a polymer electrolyte containing an ion-exchange group and an electrode provided in the polymer electrolyte. The electrode is formed of an anode and a cathode and the polymer electrolyte includes a first film and a second film. The first film and the second film have different equivalent masses, each equivalent mass being the mass of the film per mole of ion-exchange group. The anode and the cathode are in the same environment.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power generation element containing a polymer electrolyte.

Background Art

[0002] A membrane-electrode assembly (MEA) including a polymer electrolyte containing a first membrane and a second membrane, and an electrode provided on the polymer electrolyte is disclosed in Patent Document 1. The prior art disclosed in Patent Document 1 includes, in addition to the MEA, a flow path structure constituting a flow path for an anode-side fuel (oxygen) and a flow path for a cathode-side fuel (hydrogen), and a separator that partitions each cell so that oxygen and hydrogen do not mix. When hydrogen is supplied to the cathode and oxygen is supplied to the anode, ions permeate through the polymer electrolyte, and a potential difference is generated across the polymer electrolyte due to the resulting charge movement.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The prior art requires accessories such as a flow path structure and a separator, consumes energy for preparing hydrogen as fuel, and consumes energy for operating a blower that supplies oxygen and hydrogen to the cell and discharges exhaust gas after the reaction when extracting electrical energy. Since energy consumption reduces power generation efficiency, it is preferable that energy consumption and accessories are as few as possible.

[0005] The present invention has been made to meet this requirement, and an object thereof is to provide a power generation element capable of reducing energy consumption and accessories.

Means for Solving the Problems

[0006] A first aspect for achieving this object includes a cell including a polymer electrolyte containing an ion exchange group and an electrode provided on the polymer electrolyte. The electrode consists of an anode and a cathode. The polymer electrolyte includes a first membrane and a second membrane. The first membrane and the second membrane are power generation elements having different equivalent masses, which are the mass of the membrane per mole of the ion exchange group, and the anode and the cathode are in the same atmosphere.

[0007] A second aspect is that, in the first aspect, the equivalent mass of the first membrane is smaller than that of the second membrane, and at least one of the hydrogen activity and the water activity of the electrode closer to the first membrane than the second membrane is greater than at least one of the hydrogen activity and the water activity of the electrode closer to the second membrane than the first membrane.

[0008] A third aspect is that, in the second aspect, the electrode closer to the first membrane than the second membrane contains a compound containing one or more of a noble metal and Mn, and contains at least one of the noble metals.

[0009] A fourth aspect is that, in the third aspect, the electrode contains at least one of platinum and iridium oxide.

[0010] A fifth aspect is that, in any of the first to fourth aspects, a plurality of cells are connected in series, and the plurality of cells are in the same atmosphere.

[0011] A sixth aspect is that, in the fifth aspect, a conductor intervening between the cells is provided. The conductor has air permeability and electrically connects adjacent cells.

[0012] A seventh aspect is that, in any of the first to sixth aspects, the atmosphere has a hydrogen concentration of less than 1%.

[0013] An eighth aspect is that, in any of the first to seventh aspects, the polymer electrolyte has air permeability in the thickness direction.

[0014] A ninth aspect is that, in any of the first to eighth aspects, the polymer electrolyte is a proton conductor.

[0015] In the tenth aspect, in the ninth aspect, the equivalent mass of the first film is smaller than the equivalent mass of the second film, and the first film is disposed between the anode and the second film.

[0016] In the eleventh aspect, in the ninth or tenth aspect, the polymer electrolyte is one or more selected from perfluorocarbon-based and hydrocarbon-based.

Advantages of the Invention

[0017] According to the present invention, since the equivalent masses of the first film and the second film, which are the mass of the film per mole of ion exchange groups, are different from each other, and the anode and the cathode are in the same atmosphere, ions diffuse according to the difference in the activity of water in the polymer electrolyte. As the ions in the polymer electrolyte diffuse, electrons move from the anode to the cathode, and electrical energy is extracted. A flow path structure or a separator for preventing gas mixing is not required, and furthermore, the energy for operating a blower for supplying gas to the anode and the cathode and the energy for preparing hydrogen can be reduced, so that the energy consumption and accessories when extracting electrical energy can be reduced.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0019] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of the power generation element 10 in the first embodiment. The power generation element 10 includes a cell 11. The cell 11 includes a polymer electrolyte 12, and an anode 15 and a cathode 21 (electrodes) disposed on both sides of the polymer electrolyte 12. Ion conduction in the polymer electrolyte 12 is performed via water.

[0020] The polymer electrolyte 12 is a proton conductor. Proton conduction is a vehicle mechanism in which H3O ions hydrated with protons and water conduct by diffusion, and a Grotthuss mechanism in which protons move by repeating a hopping reaction in which water molecules transfer H ions is exemplified. Examples of the proton conductor include perfluorocarbon-based and hydrocarbon-based ones. Examples of the perfluorocarbon-based proton conductor include Nafion (registered trademark) and Aquivion (registered trademark) in which a sulfo group is linked to a perfluoroalkyl-based polymer. For improving the characteristics of the proton conductor, a polymer and inorganic particles may be compounded. + ion + Examples of hydrocarbon-based proton conductors include polymers in which a sulfo group is linked to an aromatic hydrocarbon-based engineering plastic. Examples of hydrocarbon-based proton conductors include polymers (SPEEK) in which a sulfo group is introduced into the main chain of polyether ether ketone. For improving the characteristics of the proton conductor, hetero elements such as fluorine, sulfur, nitrogen, and phosphorus, or units containing them may be introduced into the polymer main chain, or a phosphate group may be introduced instead of the sulfo group. A crosslinkable functional group may be introduced into the polymer to crosslink the polymer, or the sulfo group may be linked in a side chain or a comb shape instead of the main chain. A multiblock copolymer may be synthesized to control the phase separation structure of the hydrophilic part and the hydrophobic part of the membrane.

[0021]

[0022] ​The polymer electrolyte 12 includes a first membrane 13 and a second membrane 14. The first membrane 13 and the second membrane 14 have different equivalent masses, which are the masses of the membranes in the dry state per mole of ion exchange groups. In this embodiment, the equivalent mass of the first membrane 13 is smaller than that of the second membrane 14. The more ion exchange groups there are, the smaller the value of the equivalent mass. The ion exchange groups + include H3O + ions and H

[0023] ions, and examples of the groups having the property of binding to them are sulfonic groups and carboxyl groups. The value of the equivalent mass is determined by acid-base titration, Fourier transform infrared spectroscopy (FT-IR), or the like.

[0024] The first membrane 13 is joined to the second membrane 14. An example of the joining between the first membrane 13 and the second membrane 14 is by thermocompression bonding. Thermocompression bonding is, for example, applying pressure to the first membrane 13 and the second membrane 14 while heating them to a temperature below the melting points of the first membrane 13 and the second membrane 14, or applying a solution of the same components as the first membrane 13 and the second membrane 14 between the first membrane 13 and the second membrane 14 by coating or the like, and then applying pressure while heating to a temperature below the melting points of the first membrane 13 and the second membrane 14 to allow copolymerization to proceed between the first membrane 13 and the second membrane 14. Since the first membrane 13 and the second membrane 14 are joined, ions move between the first membrane 13 and the second membrane 14.

[0025] The first membrane 13 is disposed between the anode 15 and the second membrane 14. The anode 15 includes a diffusion layer 16 and a reaction layer 17. The reaction layer 17 is in contact with the first membrane 13. The diffusion layer 16 functions to collect electricity and supply gas to the reaction layer 17. Exemplary of the diffusion layer 16 are water-repellent carbon paper and carbon cloth. The reaction layer 17 includes a porous substrate 18 having electron conductivity, a catalyst 19 supported on the substrate 18, and an electrolyte 20 disposed on the substrate 18.

[0026] Exemplary of the substrate 18 are aggregates of particles and fibers of carbon such as carbon black and activated carbon, metals, metal oxides, and porous bodies of carbon and metals having continuous pores. The catalyst 19 includes noble metal catalysts and non-noble metal catalysts. Exemplary of the noble metal catalysts are noble metals such as Pt, Ir, Pd, Rh, Ru, alloys containing noble metals, and noble metal compounds such as oxides of noble metals. Exemplary of the non-noble metal catalysts are oxides containing Mn. The electrolyte 20 is exemplified by an ionomer having the same composition as the first membrane 13. The substrate 18 is a path for electrons, and the electrolyte 20 is a path for ions. The interface between the catalyst 19 and the electrolyte 20 is the site where the electrode reaction occurs.

[0027] The second membrane 14 is disposed between the cathode 21 and the first membrane 13. The cathode 21 includes a diffusion layer 22 and a reaction layer 23. The reaction layer 23 is in contact with the second membrane 14. The diffusion layer 22 functions to collect electricity and supply gas to the reaction layer 23. Exemplary of the diffusion layer 22 are water-repellent carbon paper and carbon cloth. The reaction layer 23 includes a porous substrate 24 having electron conductivity, a catalyst 25 supported on the substrate 24, and an electrolyte 26 disposed on the substrate 24.

[0028] The base material 24 includes, for example, carbon such as carbon black and activated carbon, metals, aggregates of particles and fibers of metal oxides, and porous bodies such as carbon and metal having continuous pores. The catalyst 25 includes noble metal catalysts and non-noble metal catalysts. Examples of noble metal catalysts include noble metals such as Pt, Ir, Pd, Rh, and Ru, alloys containing noble metals, and noble metal compounds such as oxides of noble metals. Examples of non-noble metal catalysts include transition metal complexes containing Fe, Co, Cu, etc., and titanium oxynitride (TiOxNy). The electrolyte 26 is exemplified by an ionomer having the same composition as the second membrane 14. The base material 24 is a path for electrons, and the electrolyte 26 is a path for ions. The interface between the catalyst 25 and the electrolyte 26 is the site where the electrode reaction occurs. A load 27 is connected between the anode 15 and the cathode 21.

[0029] The cell 11 is arranged in an environment where the operation of the polymer electrolyte 12 can be ensured, for example, at a temperature of 0°C or higher and 140°C or lower, preferably 10°C or higher and 120°C or lower, more preferably 10°C or higher and 100°C or lower. To ensure the water content of the polymer electrolyte 12, it is desirable that the relative humidity of the environment where the cell 11 is arranged is high, and the closer to 100% the better, but it may be, for example, 40% or higher, preferably 60% or higher, more preferably 80% or higher.

[0030] The anode 15 and the cathode 21 are placed in the same atmosphere. The fact that the anode 15 and the cathode 21 are placed in the same atmosphere does not only mean that the temperature, humidity, and pressure around the anode 15 are the same as those around the cathode 21. The temperature, humidity, and pressure around the anode 15 may be approximately the same as those around the cathode 21, which also means that gases of different types are not intentionally supplied to the anode 15 and the cathode 21. Therefore, the power generation element 10 can eliminate the need for a flow path structure that prevents the gas supplied to the anode 15 (cathode-side fuel) and the gas supplied to the cathode 21 (anode-side fuel) from mixing, and a separator that separates the anode 15 and the cathode 21.

[0031] The surroundings of the anode 15 and the cathode 21 are an atmosphere with a hydrogen concentration of less than 1%. The power generation element 10 is preferably disposed in an environment with a high relative humidity, such as a device that generates steam, such as a steam turbine generator or a boiler, a condenser, a hot spring, or the like. The steam generated by a device such as a boiler may be supplied to the anode 15 and the cathode 21 using a transfer device such as a pump.

[0032] Since the equivalent mass of the first membrane 13 is smaller than the equivalent mass of the second membrane 14, the water absorption rate of the first membrane 13 becomes larger than the water absorption rate of the second membrane 14. As a result, the activity of water in the polymer electrolyte 12 is large on the anode 15 side and small on the cathode 21 side, and protons diffuse through the polymer electrolyte 12 from the anode 15 side to the cathode 21 side according to the difference in activity.

[0033] At the anode 15, H2O → 2H + + 1 / 2O2 + 2e - The reaction of proceeds, and at the cathode 21, 2H + + 1 / 2O2 + 2e - → H2O reaction proceeds. Along with this, electrons move from the anode 15 to the cathode 21, so a potential difference occurs across the polymer electrolyte 12. As a result, electrical energy does work on the load 27.

[0034] Since the anode 15 and the cathode 21 are in the same atmosphere, the energy for operating a blower that supplies gas to the anode 15 or the cathode 21 and the energy for preparing hydrogen (cathode-side fuel) supplied to the anode 15 can be made unnecessary. Therefore, the energy consumption when the power generation element 10 extracts electrical energy and accessories such as a separator can be reduced. According to the power generation element 10, since electrical energy can be extracted only by installing the power generation element 10, the energy that has been released into nature can be effectively utilized.

[0035] It is preferable that at least one of the hydrogen activity and the water activity of the anode 15 is greater than at least one of the hydrogen activity and the water activity of the cathode 21. This is because by utilizing the difference in activity between the anode 15 and the cathode 21, it becomes difficult for drying out to occur, where the humidity on the anode 15 side decreases. Furthermore, since water is generated at the cathode 21, by making the activity of water or the like at the cathode 21 smaller than the activity of water or the like at the anode 15, it becomes difficult for flooding to occur, where the water generated at the cathode 21 inhibits the permeation of oxygen within the cathode 21.

[0036] Means for making at least one of the hydrogen activity and the water activity of the anode 15 greater than at least one of the hydrogen activity and the water activity of the cathode 21 include, for example, making the water repellency of the cathode 21 higher than the water repellency of the anode 15, and making the amount of catalyst contained in the anode 15 greater than the amount of catalyst contained in the cathode 21. When the amount of catalyst contained in the anode 15 is greater than the amount of catalyst contained in the cathode 21, the amount of catalyst contained in the cathode 21 with respect to the amount of catalyst contained in the anode 15 (mass ratio) is less than 1. The mass ratio may be 0.1 or less, or 0.01 or less.

[0037] The second embodiment will be described with reference to FIG. 2. In the first embodiment, the case where the polymer electrolyte 12 is a proton conductor was described. In the second embodiment, the case where the polymer electrolyte 32 is a hydroxide ion conductor will be described. For parts that are the same as those described in the first embodiment, the same reference numerals will be given and the following description will be omitted.

[0038] FIG. 2 is a cross-sectional view of the power generation element 30 in the second embodiment. The power generation element 30 includes a cell 31. The cell 31 includes a polymer electrolyte 32, and an anode 15 and a cathode 21 (electrodes) disposed on both sides of the polymer electrolyte 32.

[0039] The polymer electrolyte 32 is a hydroxide ion conductor. A hydroxide ion conductor is an anion exchange membrane that conducts hydroxide ions, and examples of materials include those in which an anion exchange group is linked to an aromatic hydrocarbon-based polymer main chain or side chain. For example, a polymer in which a trimethylammonium group is linked to polyethersulfone can be mentioned. Instead of the trimethylammonium group, an imidazolium group, a guanidinium group, a phosphonium group, etc. may be introduced. A multiblock copolymer may be synthesized to control the phase separation structure of the hydrophilic part and the hydrophobic part of the membrane.

[0040] The polymer electrolyte 32 and the polymer electrolyte 12 (see Fig. 1) may be pore-filling electrolyte membranes. A pore-filling electrolyte membrane is a membrane in which another polymer is filled in the pores of a porous substrate having pores. Examples of proton conductors include those in which aromatic polyethersulfone is filled in the pores of a porous polyimide substrate. Examples of hydroxide ion conductors include those in which an aromatic hydrocarbon-based polymer is filled in the pores of a porous crosslinked polyethylene.

[0041] The polymer electrolyte 32 includes a first membrane 33 and a second membrane 34. The equivalent masses of the first membrane 33 and the second membrane 34, which are the masses of the dry membranes per mole of ion exchange groups, are different from each other. In this embodiment, the equivalent mass of the first membrane 33 is smaller than the equivalent mass of the second membrane 34. The ion exchange group is OH - Examples of ions that can bind are cyclic ammonium and long-chain alkylammonium having the property of binding to ions. The first membrane 33 is disposed between the cathode 21 and the second membrane 34. The second membrane 34 is disposed between the anode 15 and the first membrane 33.

[0042] Since the equivalent mass of the first membrane 33 is smaller than the equivalent mass of the second membrane 34, the water absorption rate of the first membrane 33 becomes larger than the water absorption rate of the second membrane 34. As a result, the activity of water in the polymer electrolyte 12 is large on the cathode 21 side and small on the anode 15 side, and according to the difference in activity, hydroxide ions diffuse through the polymer electrolyte 32 from the cathode 21 side to the anode 15 side.

[0043] At the cathode 21, H2O + 1 / 2O2 + 2e - → 2OH - The reaction proceeds, and at the anode 15, 2OH - → H2O + 1 / 2O2 + 2e - The reaction proceeds. Along with this, electrons move from the anode 15 to the cathode 21, so a potential difference occurs across the polymer electrolyte 32. As a result, electrical energy does work on the load 27.

[0044] It is preferable that the water activity at the cathode 21 is greater than the water activity at the anode 15. This is because by utilizing the difference in activity between the anode 15 and the cathode 21, it becomes difficult for drying out to occur, where the humidity on the cathode 21 side decreases. Furthermore, since water is generated at the anode 15, by making the water activity at the anode 15 smaller than the water activity at the cathode 21, it becomes difficult for flooding to occur, where the water generated at the anode 15 inhibits the permeation of oxygen within the anode 15.

[0045] The third embodiment will be described with reference to FIG. 3. In the first and second embodiments, the power generation elements 10 and 30 including a single cell 11 and 31 were described. In contrast, in the third embodiment, a power generation element 40 including a plurality of cells 11 will be described. For parts that are the same as those described in the first embodiment, the same reference numerals will be given and the following description will be omitted.

[0046] FIG. 3 is a cross-sectional view of the power generation element 40 in the third embodiment. The power generation element 40 includes a plurality of cells 11. A conductor 41 is interposed between the cathode 21 and the anode 15 of adjacent cells 11. The conductor 41 electrically connects the adjacent cells 11.

[0047] Since a plurality of cells 11 in the power generation element 40 are connected in series, the voltage applied to the load 27 can be made larger compared to the voltage applied to the load 27 by a single cell 11. The number of cells 11 connected in series is appropriately set according to the voltage required by the load 27.

[0048] The conductor 41 is provided with a hole 42 that communicates in the thickness direction. Since the conductor 41 has air permeability in the thickness direction, the difference in the atmosphere between adjacent cells 11 can be reduced through the conductor 41. Examples of the conductor 41 include a mesh made of a noble metal or carbon.

[0049] The fourth embodiment will be described with reference to FIG. 4. In the first to third embodiments, the power generation elements 10, 30, and 40 including the polymer electrolyte 12, 32 in which the first film 13, 33 and the second film 14, 34 overlap have been described. In contrast, in the fourth embodiment, a power generation element 50 in which the polymer electrolyte 52 includes three films will be described. For the parts that are the same as those described in the first embodiment, the same reference numerals will be given and the following description will be omitted.

[0050] FIG. 4 is a cross-sectional view of the power generation element 50 in the fourth embodiment. The power generation element 50 includes a cell 51. The cell 51 includes a polymer electrolyte 52, and an anode 15 and a cathode 21 (electrodes) disposed on both sides of the polymer electrolyte 52.

[0051] The polymer electrolyte 52 is a proton conductor. The polymer electrolyte 52 includes a first film 53, a second film 54, and a third film 55 in this order. The first film 53 is in contact with the anode 15, and the third film 55 is in contact with the cathode 21. The second film 54 is joined between the first film 53 and the third film 55. The equivalent mass increases in the order of the first film 53, the second film 54, and the third film 55. As a result, the activity of water or hydrogen in the polymer electrolyte 52 is large on the first film 53 side and small on the third film 55 side, and protons diffuse through the polymer electrolyte 52 from the anode 15 side to the cathode 21 side according to the difference in activity.

[0052] The polymer electrolyte 52 has air permeability in the thickness direction. In this embodiment, a plurality of through holes 56 penetrating in the thickness direction are provided in the polymer electrolyte 52. Since the polymer electrolyte 52 has air permeability in the thickness direction, the difference in the atmosphere between the anode 15 and the cathode 21 disposed on both sides of the polymer electrolyte 52 can be reduced.

Example

[0053] The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0054] (Example 1) Aquivion E87-05S (equivalent mass 870 g / mol, thickness 50 μm) was used as the first membrane, and Nafion 117 (equivalent mass 1100 g / mol, thickness 183 μm) was used as the second membrane. After punching out the first membrane and the second membrane into circles with a diameter of 20 mm respectively, the first membrane and the second membrane were overlapped, and while heating at 80 °C, a pressure of 10 MPa was applied for crimping to obtain a polymer electrolyte of a proton conductor.

[0055] A catalyst (TEC10V50E, platinum loading 50 wt%, manufactured by Tanaka Precious Metals) with platinum supported on a conductive carbon black (VULCAN XC72, Cabot) substrate and an Aquivion D83-06A solution were mixed at a mass ratio of 1:1 to prepare a first paste. A circular membrane with a diameter of 10 mm was printed with the first paste on the first membrane of the polymer electrolyte to provide an anode on the polymer electrolyte.

[0056] Conductive carbon black (VULCAN XC72) and a 5 wt% Nafion solution were mixed at a mass ratio of 1:1 to prepare a second paste. A circular membrane with a diameter of 10 mm was printed with the second paste on the second membrane of the polymer electrolyte to provide a cathode on the polymer electrolyte. Thus, the cell in Example 1 was obtained.

[0057] (Example 2) A catalyst (TEC10V50E) and a 5 wt% Nafion solution were mixed at a mass ratio of 1:1 to prepare a third paste. A circular membrane with a diameter of 10 mm was printed with the third paste on the first membrane and the second membrane of the polymer electrolyte respectively. A cell in Example 2 was obtained in the same manner as in Example 1 except that an anode and a cathode were provided on the polymer electrolyte.

[0058] (Example 3) A circular film with a diameter of 10 mm was printed on the first and second membranes of the polymer electrolyte with the first paste, and a cell in Example 3 was obtained in the same manner as in Example 1 except that an anode and a cathode were provided on the polymer electrolyte.

[0059] (Example 4) A catalyst in which platinum was supported on a conductive carbon black (VULCAN XC72) substrate (platinum loading 0.5 wt%, manufactured by Tanaka Precious Metals) and a 5 wt% Nafion solution were mixed at a mass ratio of 1:1 to prepare a fourth paste. A circular film with a diameter of 10 mm was printed on the first membrane of the polymer electrolyte with the first paste, an anode was provided on the polymer electrolyte, a circular film with a diameter of 10 mm was printed on the second membrane of the polymer electrolyte with the fourth paste, and a cell in Example 4 was obtained in the same manner as in Example 1 except that a cathode was provided on the polymer electrolyte.

[0060] (Comparative Example 1) Two Nafion 117 membranes punched into a circular shape with a diameter of 20 mm were overlapped, and pressure was applied at 10 MPa while heating at 80 °C for crimping to obtain a polymer electrolyte. Circular films with a diameter of 10 mm were printed on both sides of the polymer electrolyte with the third paste, and an anode and a cathode were provided on the polymer electrolyte. Thereby, a cell in Comparative Example 1 was obtained.

[0061] (Comparative Example 2) Two Aquivion E87-05S membranes punched into a circular shape with a diameter of 20 mm were overlapped, and pressure was applied at 10 MPa while heating at 80 °C for crimping to obtain a polymer electrolyte. Circular films with a diameter of 10 mm were printed on both sides of the polymer electrolyte with the first paste, and an anode and a cathode were provided on the polymer electrolyte. Thereby, a cell in Comparative Example 2 was obtained.

[0062] (Measurement of Output) In Examples 1-4 and Comparative Examples 1 and 2, platinum meshes were attached to the anodes and cathodes of the cells, respectively, and the cells were electrically connected to the measuring instrument via the meshes. After all the cells were placed in a thermostatic chamber maintained at a temperature of 95°C and a relative humidity of 90% for 1 hour, the maximum value of the output of each cell was calculated from the relationship between the terminal voltage and the current measured in that state. The maximum value of the output of the cell was 6 mW in Example 1, 8 mW in Example 2, 8 mW in Example 3, and 17 mW in Example 4. On the other hand, the output of the cells in Comparative Examples 1 and 2 was 0 mW.

[0063] The cells in Examples 1-4 containing a polymer electrolyte in which two membranes with different equivalent masses were laminated had an output, while the cells in Comparative Examples 1 and 2 containing a polymer electrolyte in which two membranes with the same equivalent mass were laminated did not output. Therefore, it was clarified that a potential difference was generated between the anode and the cathode due to the difference in the activity of the membranes with different equivalent masses.

[0064] The output of the cell in Example 4 was approximately three times that of the cell in Example 1. Since the cell in Example 4 differed from the cell in Example 1 only in the material of the cathode, it was presumed that the cause of the difference in output was that the resistance of the cathode of the cell in Example 4 was reduced compared to the resistance of the cathode of the cell in Example 1.

[0065] Although the present invention has been described based on the embodiments, it is easily conceivable that the present invention is not limited to the above embodiments at all, and various improvements and modifications can be made without departing from the spirit of the present invention.

[0066] In the first embodiment and the third embodiment, the case where the cell 11 includes the polymer electrolyte 12 in which the first membrane 13 and the second membrane 14 are joined, and in the second embodiment, the case where the cell 31 includes the polymer electrolyte 32 in which the first membrane 33 and the second membrane 34 are joined has been described, but it is not necessarily limited to this. It is naturally possible to replace the polymer electrolytes of the first to third embodiments with a polymer electrolyte in which three or more membranes are joined as in the fourth embodiment.

[0067] In the first to third embodiments, the cells 11 and 31 including the polymer electrolytes 12 and 32 having no air permeability have been described, but the present invention is not necessarily limited thereto. It is of course possible to replace the polymer electrolytes of the first to third embodiments with a polymer electrolyte having air permeability as in the fourth embodiment.

Explanation of Signs

[0068] 10, 30, 40, 50 Power generation element 11, 31, 51 Cell 12, 32, 52 Polymer electrolyte 13, 33, 53 First film 14, 34, 54 Second film 15 Anode (electrode) 21 Cathode (electrode) 41 Conductor

Claims

1. A cell comprising a polymer electrolyte containing an ion exchange group and an electrode provided on the polymer electrolyte, The electrode consists of an anode and a cathode, The polymer electrolyte includes a first membrane and a second membrane, The first membrane and the second membrane are power generation elements in which the equivalent mass, which is the mass of the membrane per mole of the ion exchange group, is different from each other, The anode and the cathode are power generation elements in the same atmosphere.

2. The equivalent mass of the first membrane is smaller than the equivalent mass of the second membrane, In the power generation element according to claim 1, at least one of the hydrogen activity and the water activity of the electrode closer to the first membrane than the second membrane is greater than at least one of the hydrogen activity and the water activity of the electrode closer to the second membrane than the first membrane.

3. The electrode closer to the first membrane than the second membrane is a power generation element according to claim 2, which contains a compound containing one or more of a noble metal and Mn, and at least one of a noble metal.

4. The electrode is a power generation element according to claim 3, which contains at least one of platinum and iridium oxide.

5. A plurality of the cells are connected in series, The plurality of cells are power generation elements according to claim 1 or 2 in the same atmosphere.

6. It includes a conductor interposed between the cells, The conductor has air permeability and electrically connects adjacent cells, which is a power generation element according to claim 5.

7. The atmosphere is a power generation element according to claim 1 or 2, in which the hydrogen concentration is less than 1%.

8. The polymer electrolyte has air permeability in the thickness direction, which is a power generation element according to claim 1 or 2.

9. The power generation element according to claim 1 or 2, wherein the polymer electrolyte is a proton conductor.

10. The equivalent mass of the first membrane is smaller than the equivalent mass of the second membrane, The power generation element according to claim 9, wherein the first membrane is disposed between the anode and the second membrane.

11. The power generation element according to claim 9, wherein the polymer electrolyte is one or more selected from perfluorocarbon-based and hydrocarbon-based.

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