JP4677604B2 - Fuel cell and fuel cell reaction measuring device - Google Patents

Description

  The present invention relates to a fuel cell used for research and evaluation of battery characteristics and battery life of a polymer electrolyte fuel cell (PEFC), and a fuel cell reaction measuring device using the same.

A single cell of a polymer electrolyte fuel cell includes a membrane electrode assembly (MEA) in which an anode electrode is bonded to one surface of a solid polymer electrode membrane and a cathode electrode is bonded to the other surface, and an anode electrode of the membrane electrode assembly And an anode separator that forms a fuel introduction space serving as a fuel gas channel between the anode electrode surface and an oxygen gas channel between the cathode electrode surface of the membrane electrode assembly and the cathode electrode surface. The cathode side separator that forms the oxygen introduction space is configured such that the anode side separator and the cathode side separator sandwich the membrane electrode assembly.
Then, by forming a stack structure in which a plurality of single cells are connected in series, a stacked solid polymer fuel cell is formed, and a desired DC voltage is obtained.

  In order to popularize polymer electrolyte fuel cells, it is necessary to solve various technical problems including cost. For example, since the battery performance of a fuel cell deteriorates with the passage of operating time, the battery life associated with the deterioration is an important issue. In order to solve such a technical problem, it is necessary to analyze a chemical reaction occurring in the single fuel cell.

From this point of view, one of the researches published so far is to form a visualization unit cell with a part of the cathode separator as a light transmission window, and observe the behavior of humidified water and generated water in the cell. There is something that is. According to this, since the voltage characteristics and life characteristics of the battery are affected by the moisture of the humidified water and reaction product water inside the battery, it is meaningful to directly observe the movement of the generated water in the single cell. Has been reported. (Non-Patent Document 1).
Proceedings of the 12th Fuel Cell Symposium, May 11-12, 2005, Tokyo, 78P-81P, Moisture transfer analysis of polymer electrolyte fuel cells using a visualization single cell device, Mitsubishi Electric Corporation Research Institute of Technology Hiroaki Shigeoka, Shoji Yoshioka

As described above, by using a visualized fuel battery cell in which a part of the separator is made of a light-transmitting material, it is possible to observe the distribution of generated water generated by a chemical reaction in the cell and the moisture such as humidified water, thereby The relationship with performance has been analyzed.
However, since it is not only moisture that affects changes in battery performance, it is not sufficient to analyze the battery reaction simply by observing the moisture distribution and its change over time.
It is known that the cell temperature also affects the chemical reaction other than moisture. It is useful to visualize the temperature distribution, but the data of the temperature distribution alone is not sufficient.

  In the first place, the battery reaction is that oxygen and hydrogen combine to generate water. Therefore, the oxygen distribution should have a great influence. Until now, the visualization of moisture and temperature alone has been studied, but due to the lack of an effective means of measuring the oxygen distribution in fuel cells, the oxygen concentration distribution has been fully studied. It wasn't.

Moreover, oxygen may leak from the oxygen introduction space side to the fuel introduction space due to deterioration of battery performance, failure, or other causes. For this reason, detecting the oxygen concentration in the fuel introduction space on the anode electrode side where oxygen originally does not exist is useful for studying other problems such as battery performance deterioration.
Conversely, substances in the fuel introduction space may leak toward the oxygen introduction space due to deterioration of battery performance or the like. For this reason, detecting fuel, reaction products, and the like that should originally be in the fuel introduction space in the oxygen introduction space is also useful for studying defects such as cell performance degradation.

Accordingly, an object of the present invention is to provide a fuel cell in which the distribution of oxygen in the cell is visualized.
Another object of the present invention is to provide a fuel cell that visualizes the distribution of leakage of oxygen and fuel between the oxygen introduction space and the fuel introduction space.
In addition, the present invention analyzes the oxygen behavior and oxygen distribution in the cell, or measures the change over time of the oxygen distribution in the cell and improves the oxygen distribution in the cell to improve the battery characteristics such as voltage characteristics and life. It is an object of the present invention to provide a fuel cell that can be used for research and evaluation for developing a fuel cell with excellent performance, and a fuel cell reaction measuring device using the fuel cell.

  The present invention also provides a fuel cell measuring device capable of simultaneously measuring the distribution of oxygen and other substances generated in other cells such as moisture and the temperature distribution, and comprehensively analyzing a plurality of parameters affecting battery performance. The purpose is to provide.

  On the other hand, in a methanol fuel cell, when an aqueous methanol solution or its vapor is supplied as fuel to the fuel introduction space on the anode side, unreacted methanol, carbon dioxide of the reaction product, and a small amount of methanol oxidation intermediate are discharged from the outlet on the anode side. Discharged. Some methanol crosses over the electrolyte membrane and reaches the cathode side, where it is oxidized to carbon dioxide and finally discharged from the cathode outlet. Monitoring the degree of reaction progress on the anode side, the degree of environmental pollutants, or the spatial distribution on the cathode side of the amount of methanol crossing over (corresponding to the amount of carbon dioxide produced at the cathode) can improve battery characteristics and improve cell performance. Although it is important in determining the optimal operating conditions, so far these materials have not been visualized and observed.

Therefore, an object of the present invention is to provide a fuel cell in which the distribution of methanol and its oxidation product is visualized in the case of a methanol fuel cell. Further, in the case of a methanol fuel cell, it is intended to measure a reaction intermediate in an anode reaction product, particularly to measure an aldehyde and visualize a crossover methanol amount. It is another object of the present invention to provide a visualized fuel cell and a fuel cell measurement device that are useful for optimizing battery operating conditions and improving catalysts and electrolyte materials in the case of a methanol fuel cell.
Another object of the present invention is to provide a fuel cell that visualizes the distribution of oxygen, methanol, and other oxidation products in the cell in the case of a methanol fuel cell.

The fuel cell of the present invention, which has been made to solve the above-mentioned problems, comprises a membrane electrode assembly in which an anode electrode is joined to one side of a solid polymer electrolyte membrane and a cathode electrode joined to the opposite side; An anode-side separator that faces the anode electrode of the assembly and forms a fuel introduction space; and a cathode-side separator that conducts to the cathode electrode and faces the cathode electrode of the membrane electrode assembly and forms an oxygen introduction space; The membrane electrode assembly is sandwiched between the anode-side separator and the cathode-side separator, and the oxygen monitor substance whose optical characteristics change depending on the oxygen concentration is fixed to either the oxygen introduction space and / or the oxygen concentration measurement site in the fuel introduction space. If the oxygen monitor substance is fixed to the anode side separator and / or part of the cathode side separator, Comprising a light transmitting window formed in the outside from through the light transmission window oxygen introduction space of the fuel cell or / and the change in the oxygen monitor substances in the fuel introduction space in optically measurable configured fuel cell As oxygen monitor substances, multiple types of oxygen monitor substances with different detection wavelength ranges are fixed at different positions in the oxygen introduction space and / or the fuel introduction space, and the oxygen concentration at each location is measured independently. Yes.

  According to the present invention, a single cell is formed by a membrane electrode assembly, and an anode side separator and a cathode side separator sandwiching the membrane electrode assembly, and a part of the cathode side separator, part of the anode side separator, or both side separators are formed. A light transmission window is formed so that the cathode electrode surface, the anode electrode surface, or both electrode surfaces can be observed from the outside of the single cell. Further, in the oxygen introduction space formed facing the cathode electrode, an oxygen monitor substance is fixed at a site where the oxygen concentration is to be measured. Alternatively, in the fuel introduction space formed facing the anode electrode, an oxygen monitor substance is fixed at a location where oxygen leaking from the oxygen introduction space side to the fuel introduction space side is to be detected. Since the optical characteristics of the oxygen monitor substance change depending on the oxygen concentration, the optical characteristics of the oxygen monitor substance can be optically observed from the outside of the fuel cell through the light transmission window. Observe oxygen distribution in the cell, changes in oxygen distribution over time, or oxygen leakage distribution.

Here, for the oxygen monitor substance fixed in the oxygen introduction space or the fuel introduction space, for example, a substance whose light emission luminescence characteristic or light absorption characteristic changes or color changes can be used as the light characteristic, By using a light transmissive material corresponding to the light emission luminescence wavelength region, the light absorption wavelength region, and the color development wavelength region for the light transmission window, a change can be observed from the outside through the light transmission window.
Moreover, the space shape of the fuel introduction space formed by the anode side separator and the oxygen introduction space formed by the cathode side separator is not particularly limited, but in the actual fuel cell, a flow path for flowing fuel gas and oxygen is formed. Therefore, it is preferable to make it the same shape as such a flow path.
A plurality of types of oxygen monitor substances having different detection wavelength ranges are fixed at different positions in the oxygen introduction space and / or the fuel introduction space, and the oxygen concentration at each location is measured independently. As the different materials, for example, a plurality of types of metal porphyrin complexes having different emission luminescence wavelengths can be used.

According to the present invention, the distribution of oxygen in the fuel cell can be visualized. As a result, it is possible to analyze the oxygen behavior and oxygen distribution in the cell, or the oxygen leakage distribution on the anode side, and to measure the temporal change of the oxygen distribution in the cell. And it can utilize for the research and cell evaluation for improving the oxygen distribution in a cell, and developing the fuel cell excellent in battery performance, such as a voltage characteristic and a lifetime.
In particular, according to the present invention, a plurality of types of oxygen monitor substances having different detection wavelength ranges (a plurality of types of materials having different emission luminescence wavelength regions, light absorption wavelength regions, and color development wavelength regions) are fixed to different parts, respectively, By observing via, it becomes possible to measure the oxygen concentration of each part independently.

(Means and effects for solving other problems)
In the above invention, a flow path wall that forms an oxygen flow path in the oxygen introduction space and / or a flow path wall that forms a fuel flow path in the fuel introduction space is formed, and the flow path wall is between the cathode electrode and the cathode side separator. Alternatively, it may be formed of a conductive material that conducts between the anode electrode and the anode-side separator.
According to the present invention, an oxygen introduction space and a fuel introduction space having a flow path structure similar to that of a single cell of an actual fuel cell can be provided, so that electrons generated by a chemical reaction in the single cell can also be actually fueled. An electron flow similar to that of a battery can be generated, and an oxygen distribution in a situation close to that of an actual fuel cell single cell can be observed.
Specifically, in an actual fuel cell unit cell, the cathode electrode surface side of the cathode separator has a rib structure (the same applies to the anode electrode surface side of the anode side separator), and the groove portion of the rib serves as a gas flow path. Since the channel wall itself is made in contact with the cathode electrode surface, the same rib structure is formed on the cathode side separator, so that the evaluation is performed in the same channel state as that of an actual fuel cell single cell. Can do.

In the above invention, at least a part of the channel wall may be formed of a light transmissive material, and the oxygen monitor substance may be fixed to the surface of the channel wall.
According to the present invention, it is possible to visualize the contact portion between the flow passage wall and the cathode electrode with respect to the portion of the flow passage wall formed of the light transmissive material, and fix the oxygen monitor substance on the surface of the contact portion. If this is done, the oxygen distribution at the contact portion can also be measured.

In the above invention, a transparent conductive film may be formed on the flow path wall formed of the light transmissive material.
According to the present invention, the flow path wall formed of the light-transmitting material can be made conductive, so that the evaluation by visualization can be performed in a state where there is conductivity like the actual flow path wall. it can.

In the above invention, the oxygen monitor substance may be a light-emitting luminescent material whose light-emitting luminescence intensity changes depending on the oxygen concentration, or a color-forming material whose color changes depending on the oxygen concentration.
In the case of a light-emitting luminescent material whose light-emitting luminescence intensity varies depending on the oxygen concentration, the oxygen concentration in the vicinity of the oxygen monitor substance can be measured by observing the light-emitting luminescence generated by irradiating excitation light from the light transmission window. In the case of a coloring material that changes color depending on the oxygen concentration, the oxygen concentration in the vicinity of the oxygen monitor substance can be measured by irradiating white light and observing the reflected light from the coloring material.

In the above invention, the oxygen monitor substance may be a light-emitting luminescent material containing a metal porphyrin or a metal porphyrin complex.
Here, it is preferable that the metal which comprises metal porphyrin is an iron ion or a cobalt ion. Alternatively, a polymer complex in which a polymer having a ligand is coordinated to iron porphyrin or cobalt porphyrin can be used. As the polymer having the ligand, for example, a copolymer of vinylimidazoles and methacrylate can be used. These light-emitting luminescent materials generate light-emitting luminescence by laser light irradiation (for example, wavelength 532 nm), and the light-emitting luminescence intensity changes according to the oxygen concentration. Therefore, an oxygen monitor using light-emitting luminescence can be realized .

Moreover, since the metal porphyrin or the complex thereof can be formed as a film at the measurement site, it can be easily attached to the measurement site in the oxygen introduction space.

In the above invention, a coloring material containing blackened titanium as the oxygen monitor substance may be used .
According to the present invention, it is possible to realize an oxygen monitor that utilizes changes in color development .

In the above invention, a metal film (for example, gold) reflecting infrared light may be formed on a part of the cathode electrode surface and / or a part of the anode electrode surface.
According to this invention, since the infrared light can be efficiently reflected by the metal film that reflects the infrared light, the infrared light of any one of water, methanol, methanol oxidation intermediate, and carbon dioxide from the outside. By irradiating infrared light in the absorption wavelength region and detecting the reflected light, the influence of absorption by these substances in the reflected light can be effectively measured.

Further, in order to solve the above problems, the fuel cell reaction measuring device of the present invention, which has been made from another point of view, is one of the above-described fuel cells according to the present invention, and light detection for measuring the optical characteristics of the oxygen monitor substance. And an oxygen measuring optical system for guiding the detection light from the oxygen monitor substance to the light detector through the light transmission window.
According to the present invention, the detection light emitted from the oxygen monitor substance is guided to the photodetector through the light transmission window of the visualized fuel cell single cell by the oxygen measuring optical system. The photodetector measures the optical characteristics of the oxygen monitor substance by the detection light guided from the light transmission window, and measures the oxygen concentration. This makes it possible to realize a reaction measuring device that can visualize the behavior and distribution of oxygen during reaction in a single fuel cell and can measure in real time.

In the invention of the fuel cell reaction measuring device, when the oxygen monitor substance is a luminescent material, the oxygen monitor substance may be irradiated with excitation light from a light transmission window using an oxygen measurement optical system.
According to this invention, a light-emitting luminescence substance that emits light emission luminescence by irradiating excitation light can be used as an oxygen monitor substance, and the oxygen measurement optical system that guides the detection light to the photodetector is shared, so that the excitation light Can be made into a compact device configuration.

In the invention of the fuel cell reaction measuring device, a material that transmits the visible light region and the infrared light region is used for the light transmission window, and at least infrared light of water, methanol, methanol oxidation intermediate, or carbon dioxide is used. An infrared absorption measurement optical system that irradiates infrared light in the absorption wavelength range from the light transmission window and guides the reflected light to an infrared detector for infrared absorption spectrum measurement, and emits light from the membrane electrode assembly through the light transmission window. Further comprising at least one of a temperature measuring optical system that guides the black body radiation to the temperature detecting infrared detector, and together with the oxygen concentration, any one of the water, methanol, methanol oxidation intermediate, and carbon dioxide Measurements may be performed for either or both of the infrared absorption and / or temperature of the material.
According to the present invention, since the oxygen distribution in the fuel cell and either or both of the moisture, methanol, methanol oxidation intermediate, carbon dioxide distribution and temperature distribution can be measured simultaneously, the battery performance is affected. Multiple parameters to be given can be analyzed comprehensively.

In the invention of the fuel cell reaction measuring apparatus, the oxygen measuring optical system includes an optical system including a concave and convex surface mirror, and the infrared absorption measuring optical system or the temperature measuring optical system or these two measuring optical systems are concave portions of the oxygen measuring optical system. You may make it share the optical system part which consists of a convex mirror as a common optical system.
Here, a Schwarzschild mirror or a Cassegrain mirror can be used as the optical system composed of the uneven surface mirror.
According to the present invention, an optical system having a wide field of view and excellent imaging performance can be used. Further, when a Schwarzschild mirror is used as the concavo-convex mirror, the distance between the measurement optical system and the fuel cell can be increased, and the influence of heat from the fuel cell can be avoided as much as possible.

In the invention of the fuel cell reaction measuring device, a scanning unit that relatively scans the fuel cell may be provided with respect to the common optical system.
Here, the scanning means may scan either the common optical system or the fuel cell side.
According to the present invention, the measurement is performed by scanning the fuel cell relative to the common optical system by the scanning unit, so that the oxygen distribution data for a wide range of the fuel cell or the red of water and the like is also collected. External absorption measurement distribution data and temperature distribution data can be measured simultaneously.

In the invention of the fuel cell reaction measuring device, a light-transmitting cover is attached so as to provide a space outside at least one of the separators of the fuel cell, and temperature adjustment is performed between the light-transmitting cover and the separator. You may make it provide the temperature control mechanism which supplies the gas for this.
According to the present invention, even if heat is generated due to a reaction in the fuel battery cell, an increase in the cell temperature can be suppressed by the heat dissipation action caused by the temperature adjusting mechanism flowing the temperature adjusting gas into the separator outer space.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and it is needless to say that various aspects are included without departing from the spirit of the present invention.

(Single fuel cell)
FIG. 1 is a cross-sectional view showing a configuration of a fuel cell single cell according to an embodiment of the present invention.
The single fuel cell 1 includes a membrane electrode assembly (MEA) 11, an anode side separator 12, and a cathode side separator 13, and the anode side separator 12 and the cathode side separator 13 sandwich the membrane electrode assembly 11. is doing.

  In the membrane / electrode assembly 11, an anode electrode 15 and a cathode electrode 16 are joined to both surfaces of a polymer electrolyte membrane 14. The anode electrode 15 includes a catalyst metal layer 15a such as a platinum catalyst and a conductive porous support layer 15b such as carbon paper. Similarly, the cathode electrode 16 includes a catalyst metal layer 16a such as platinum and a conductive porous layer such as carbon paper. And a quality support layer 16b.

  The anode-side separator 12 includes a metal flat plate 20 and a rib structure 21. These may be formed integrally. Instead of the rib structure 21, a spacer may be simply provided. The rib groove 22 formed by the rib structure 21 serves as a fuel gas passage through which a fuel gas such as hydrogen flows, and functions as a fuel introduction space.

The cathode-side separator 13 includes a metal flat plate 23 and a rib structure 24 similar to those of the anode-side separator 12 (instead of the rib structure 24, a spacer may be simply provided). The cathode side separator 13 is further provided with a hole in a part of the flat plate 23, and a light transmission window 25 made of a light transmitting material is provided in the hole part. The material of the light transmission window may be any material that transmits laser light applied to the porphyrin film described later and light-emitting luminescence emitted from the porphyrin film. In this embodiment, glass is used. Note that when infrared light is observed simultaneously, a material that transmits infrared light is used. Specifically, a window material such as calcium fluoride, magnesium fluoride, barium fluoride, zinc selenide, zinc sulfide, or fluorine-based resin is used. The periphery of the light transmission window 25 is sealed with a gasket (not shown).
The rib groove 26 formed by the rib structure 24 serves as an oxygen flow path through which oxygen flows, and functions as an oxygen introduction space.
It is more preferable to form a transparent conductive film on the inner surface of the light transmission window 25 so that the rib structure 24 in contact with the light transmission window 25 is also electrically connected to the cathode side separator 23.

  A porphyrin film whose emission luminescence intensity changes according to the oxygen concentration is applied to a part of the rib groove 26 in the region that can be observed from the light transmission window 25 of the cathode side separator 13 to form oxygen monitors 30a to 30c. . The oxygen monitor includes an oxygen monitor 30a formed on the surface of the light transmission window 25 and the flat plate 23, an oxygen monitor 30b formed on the side wall of the rib structure 24, and an oxygen monitor 30c formed on the cathode electrode 16. The light emission luminescence intensity changes in accordance with the oxygen concentration at.

Next, the operation of the single fuel cell 1 will be described. When hydrogen, which is a fuel gas, flows through the rib groove 22 (fuel introduction space) and oxygen flows through the rib groove 26 (oxygen introduction space) with the membrane electrode assembly (MEA) 11 interposed therebetween, the hydrogen is a catalyst of the anode electrode 15. The metal layer 15a is separated into hydrogen ions and electrons by the platinum catalyst. Hydrogen ions selectively permeate the polymer electrolyte membrane 14.
The permeated hydrogen ions react with oxygen in the catalytic metal layer 16a of the cathode electrode 16 to become water. Electrons generated at the electrode at this time generate an electromotive force from the anode electrode 15 toward the cathode electrode 16 through an external load, and the electrons flow.

The fuel cell single cell 1 generates electric power by causing the above reaction, but the emission luminescence intensity of the oxygen monitors 30a to 30c in the single cell 10 depends on the distribution of oxygen in the cathode electrode 16 and the cathode separator 13. Changes.
Therefore, by observing the emission luminescence intensity through the light transmission window 25, the oxygen distribution in the single fuel cell during the reaction can be measured.

FIG. 2 is a partial cross-sectional view showing a configuration of a fuel cell single cell 2 according to another embodiment of the present invention. In the figure, the same components as those in FIG.
In the single fuel cell 2, a part of the rib structure 24 in FIG. 1 is replaced with a light transmitting rib 31 using a light transmitting material such as glass. A transparent conductive film 32 is formed on the surface of the light transmissive rib 31 so as to be electrically connected to both the cathode electrode 16 and the flat plate 23. At the position where the light transmissive rib 31 and the light transmissive window 25 are in contact, a transparent conductive film may be applied to the light transmissive window 25 to ensure conductivity.

An oxygen monitor 30d made of a porphyrin film is applied to the contact surface between the light-transmitting rib 31 and the cathode electrode 16 (the oxygen monitors 30a to 30c may be applied to the same locations as in FIG. Omitted). In order to maintain the conductivity between the transparent conductive film 32 formed on the light-transmitting rib 31 and the cathode electrode 16, the oxygen monitor 30d is applied only to a part of the contact surface.
According to the single fuel cell 2, it is possible to observe the oxygen distribution directly below the light transmitting rib 31, so that the change and influence of the oxygen distribution in the vicinity of the flow path wall can be evaluated in more detail.

  In the above description, porphyrin which is a light-emitting luminescence material is used as the oxygen monitors 30a to 30c, but a color forming material may be used instead. For example, blackened titanium may be used. Blackened titanium oxidizes when it comes into contact with oxygen and turns white. Therefore, by observing a color change from the light transmission window 25, the oxygen distribution can be measured.

In the two embodiments described above, the measurement of other substances such as moisture is not particularly considered. However, when the moisture and the like are detected together with the oxygen concentration, the conductivity of the cathode electrode 16 in the membrane electrode assembly 11 is not detected. A part of the surface of the porous support layer 16b may be coated with a metal film that reflects infrared light, such as gold, so that the infrared light can be easily reflected.
The presence of the metal film that reflects the infrared light enables the infrared light to be efficiently reflected, so that infrared light in the infrared light absorption wavelength region such as moisture is irradiated from the outside. By detecting the reflected light, the distribution can be measured with high sensitivity from the change in the infrared light absorption wavelength region such as moisture in the reflected light. Although not shown, the same applies to the case where a metal film for reflecting infrared light is formed on the conductive porous support layer of the anode electrode.

FIG. 3 is a cross-sectional view showing the configuration of a single fuel cell 3 that is another embodiment of the present invention. This single fuel cell 3 can be used to detect and visualize when oxygen leaks from the oxygen introduction space side to the fuel introduction space due to deterioration or failure of battery performance. In addition, in the case of a methanol fuel cell using methanol aqueous solution or its vapor as fuel, substances (methanol, methanol oxidation intermediate, carbon dioxide, moisture or oxygen leaked from the cathode side) that may exist on the anode side are removed. It can be used for detection and visualization.
In the figure, the same components as those in FIG.

In the single fuel cell 3, a light transmission window 25 ′ is also attached to the metal flat plate 20 of the anode side separator 12. A porphyrin film is applied to a part of the rib groove 22 in the region that can be observed from the light transmission window 25 ′, and an oxygen monitor 30d fixed to the light transmission window 25 ′, an oxygen monitor 30e fixed to the rib structure 21, An oxygen monitor 30f fixed to the conductive porous support layer 15b of the anode electrode 15 is formed. As for these, the light emission luminescence intensity changes according to the oxygen concentration in each position. Note that the oxygen monitors 30d, 30e, and 30f at different positions may be detected independently by being of different types. For example, the oxygen concentration at the position of the light transmission window 25 ′ and the oxygen concentration of the conductive porous support layer 15b may be individually measured (the same applies to the cathode electrode side).
In this embodiment, the oxygen concentration distribution on each side can be measured from the light transmission window 25 on the cathode side and the light transmission window 25 ′ on the anode side.
Further, if infrared absorption is observed from the light transmission window 25 ′ on the anode side by a fuel cell reaction measuring device described later, methanol, methanol oxidation intermediate, carbon dioxide, and moisture can also be observed.

(Fuel cell reaction measuring device)
Next, a fuel cell reaction measuring device that measures the reaction of the fuel cell in real time using the above-described single fuel cell 1 (or 2, 3) will be described.
FIG. 4 is a diagram showing a schematic configuration of a fuel cell reaction measuring apparatus according to an embodiment of the present invention. In this fuel cell reaction measuring device 4, the oxygen concentration in the fuel cell single cell 1, infrared absorption such as moisture, and temperature are measured simultaneously.
The fuel cell reaction measurement device 4 includes a stage mechanism 41, a shared unit 42, a temperature measurement unit 43, an infrared absorption measurement unit 44, and an oxygen concentration measurement unit 45.
In addition, the fuel cell single cell 1 used in the present embodiment can observe infrared light to visible light by using calcium fluoride as a light transmission window material.

  The stage mechanism 41 includes an XY stage 51 on which the fuel cell single cell 1 is placed, and a stage drive control unit 52 that performs control to move the XY stage 51 in the XY direction on a two-dimensional surface. As the XY stage 51 and the stage drive control unit 52, a well-known XY stage apparatus attached to a commercially available microscope apparatus or the like can be used.

The shared unit 42 includes an optical system using a Schwarzschild mirror 53 in which a convex mirror and a concave mirror are combined, beam splitters 54 and 55 formed of multilayer films, a mirror 56, and a relay optical system lens 57 that sequentially adjusts the focal point. 58.
The Schwarzschild mirror 53 selects a convex mirror and a concave mirror that increase the distance (operating distance) from the single fuel cell 1 so that the influence of heat generated from the single fuel cell 1 does not easily affect the optical system. I have to.

The beam splitter 54 uses a selectively transmissive element that transmits infrared rays having a wavelength range of 5 to 10 μm and reflects infrared rays and visible rays having a shorter wavelength range than that. Thereby, black body radiation (infrared ray having a wavelength of 5 μm or more) reflecting the temperature of the single fuel cell 1 is transmitted through the beam splitter 54 and guided to the temperature measurement unit 43. On the other hand, light having a wavelength shorter than 5 μm used for infrared absorption measurement of moisture, methanol, methanol oxidation intermediate, and carbon dioxide among infrared rays from the single fuel cell 1 is reflected and directed to the beam splitter 55. .

  As the beam splitter 55, a selectively transmissive element that separates visible light and infrared light is used. That is, a selectively transmissive element that transmits light having a wavelength range of 1 μm or less and reflects infrared light having a wavelength range of 1 μm to 5 μm is used. Thereby, infrared light in the wavelength range of 2.5 μm to 5 μm used for detection of moisture, methanol, methanol oxidation intermediate, and carbon dioxide is reflected by the beam splitter 55 and guided to the infrared absorption measurement unit 44. . On the other hand, visible light used for detecting the oxygen concentration passes through the beam splitter 55 and is directed to the mirror 56.

The mirror 56 reflects visible light and guides it to the oxygen concentration measurement unit 45.
The relay optical system lenses 57 and 58 are arranged to adjust the focal position of the detection light guided to the infrared absorption measurement unit 44 and the oxygen concentration measurement unit 45, and are focused on the detectors of the measurement units 44 and 45, respectively. Is coming.

The temperature measurement unit 43 is disposed on the shared unit 41 and includes a temperature measurement infrared detector 61 and a filter 62.
The filter 62 has a filter surface divided into two or three regions, and each region can selectively transmit different infrared wavelengths. Each region of the filter is sequentially inserted into the optical path (for example, using a rotating sector mechanism), and the infrared intensity at that time can be measured by the infrared detector 61 for temperature measurement.
By measuring the infrared intensity ratio of a few infrared rays transmitted through the filter 62, the temperature emitted from the single fuel cell 1 can be measured.

The infrared absorption measurement unit 44 is disposed on the beam splitter 55 and includes an infrared light source 71, a beam splitter 72, an infrared absorption measurement infrared detector 73, and a filter 74.
The infrared light source 71 emits incident infrared light in a wavelength range of 1 μm to 5 μm. Incident infrared light is applied to the fuel cell single cell 1 via the beam splitter 72 and the optical system of the shared unit 42, and reflected infrared light from the incident infrared light is also passed through the optical system of the shared unit 42. Is reflected by the light beam and is further transmitted through the beam splitter 72. The reflected infrared light transmitted through the beam splitter 72 reaches the filter 74. The filter 74 has a filter surface divided into a plurality of regions having transmission wavelengths corresponding to the measurement substance, and each region can selectively transmit different infrared wavelengths within a wavelength range of 2.5 μm to 5 μm. It is. Each region of the filter 74 is sequentially inserted on the optical path, and measurement is performed by the infrared detector 73 for infrared absorption measurement.
By measuring the intensity ratio of these infrared rays, moisture, methanol, methanol oxidation intermediate, and carbon dioxide can be measured.

The oxygen concentration measurement unit 45 is disposed on the mirror 56, and includes a laser light source 81 for light emission luminescence excitation, a beam splitter 82, a visible light detector 83, and a filter 84 that cuts excitation light. The
As the laser light source 81, for example, a green laser having a wavelength of 532 nm is used, and incident laser light is irradiated toward the beam splitter 82. The incident laser light is applied to the single fuel cell 1 through the beam splitter 82 and the optical system of the shared unit 41. In the fuel cell single cell 1, porphyrin is fixed at a position where the oxygen concentration is to be measured, and when this is irradiated with laser light, light emission luminescence is emitted. The reflected laser light from the single fuel cell 1 and the emission luminescence from the porphyrin are guided to the mirror 56 through the optical system of the shared unit 41 and reflected, and pass through the beam splitter 82. The reflected laser light and the emitted luminescence transmitted through the beam splitter 82 reach the filter 84. The filter 84 cuts the reflected laser light, transmits the emitted luminescence, and guides it to the visible light detector 83. The visible light detector 83 can measure the oxygen concentration by measuring the luminescence intensity.

Next, the measurement operation by the fuel cell reaction measurement device 4 will be described.
The fuel cell single cell 1 is placed on the XY stage 51, and the XY stage is driven so that the light transmitting window 25 is directly below the Schwarzschild mirror 53, and the position is determined.
Subsequently, infrared light for infrared absorption measurement from the infrared light source 71 and excitation light from the laser light source 81 are irradiated. The temperature data, infrared absorption data, and oxygen concentration data are measured simultaneously and independently by the temperature measurement infrared detector 61, the infrared absorption measurement infrared detector 73, and the visible light detector 83.
Subsequently, the XY stage is driven and the same measurement is repeated at different positions. In this way, temperature, infrared absorption, and oxygen concentration distribution data are collected. By collecting the collected data and displaying a list on a monitor screen (not shown), mapping data of these temperature distribution, infrared absorption distribution, and oxygen concentration distribution can be obtained.
The above operation is sequentially performed from the cathode side light transmission window 25 and from the anode side light transmission window 25 ′.

In this embodiment, temperature, infrared absorption, and oxygen concentration data are measured simultaneously, but each may be measured independently.
In this embodiment, a single fuel cell whose emission luminescence intensity changes depending on the oxygen concentration is used. Instead, a coloring material that changes color depending on the oxygen concentration (for example, blackened titanium that changes to white by oxidation) is used. The used fuel cell single cell may be used. In this case, instead of the laser light source 81, a white light source may be attached for illumination.

FIG. 5 is a diagram showing a schematic configuration of a fuel cell reaction measuring device 5 which is another embodiment of the present invention. In this embodiment, the temperature of the fuel cell is kept constant. In the figure, the same components as those in FIG.
In this fuel cell reaction measuring device 4, a light transmission cover 92 having an air flow path 91 is attached on the fuel cell single cell 1 (or 2, 3). A dry air having a constant temperature is sent from 93. With this configuration, the heat generated in the single fuel cell 1 is temperature-controlled by dry air, and can be measured at a constant temperature.

  FIG. 6 is a diagram showing a schematic configuration of an oxygen concentration measuring unit of the fuel cell reaction measuring device 6 according to another embodiment of the present invention. In this embodiment, when measuring the oxygen concentration distribution of the fuel battery cell 1, the measurement can be performed independently for each measurement place. Although the portions corresponding to the temperature measurement unit 43 and the infrared absorption measurement unit 44 described with reference to FIG. 4 are omitted, these may be measured simultaneously using a relay optical system.

  The optical system of this embodiment includes a Schwarzschild mirror 53 in which a convex mirror and a concave mirror are combined, a laser light source 81 for exciting luminescence excitation, beam splitters 82a and 82b, filters 84a and 84b for cutting excitation light, Visible light detectors 83a and 83b.

A green laser having a wavelength of 532 nm is used as the laser light source 81, and incident laser light is irradiated toward the beam splitter 82a. Incident laser light is applied to the fuel cell single cell 1 via beam splitters 82 a and 82 b and a Schwarzschild mirror 53. The visible light detector 83 a is focused on the surface of the cathode electrode of the membrane electrode assembly (MEA) 11, and the visible light detector 83 b is focused on the surface of the light transmission window 25.
On the other hand, the first porphyrin 30g (for example, iron porphyrin) is fixed to the surface of the light transmission window 25 of the fuel cell single cell 1, and the second porphyrin 30h is fixed to the surface of the cathode electrode of the membrane electrode assembly (MEA) 11. (For example, cobalt porphyrin) is fixed.

  With such a configuration, the oxygen concentration distribution can be measured simultaneously on the upper and lower surfaces of the oxygen introduction space, and distribution information in each depth direction can also be obtained.

  INDUSTRIAL APPLICABILITY The present invention can be used in a reaction measuring device for research and development that improves the battery performance and battery life of a fuel cell.

Sectional drawing which shows the structure of the fuel cell single cell which is one Embodiment of this invention. Sectional drawing which shows the structure of the fuel cell single cell which is other one Embodiment of this invention. Sectional drawing which shows the structure of the fuel cell single cell which is other one Embodiment of this invention. 1 is a block diagram showing a schematic configuration of a fuel cell reaction measuring device according to an embodiment of the present invention. The block diagram which shows schematic structure of the fuel cell reaction measuring apparatus which is other one Embodiment of this invention. The block diagram which shows schematic structure of the fuel cell reaction measuring apparatus which is other one Embodiment of this invention.

Explanation of symbols

1, 2: Fuel cell single cell 3: Fuel cell reaction measuring device
11: Membrane electrode assembly (MEA)
12: Anode side separator 13: Cathode side separator 14: Polymer electrolyte membrane 15: Anode electrode 16: Cathode electrode 20, 23: Conductive plate 21, 24: Rib structure 22: Rib groove (fuel introduction space)
25, 25 ': Light transmission window 26: Rib groove (oxygen introduction space)
30a-30h: Oxygen monitor (porphyrin membrane)
31: Light transmission rib 32: Transparent conductive film 41: Stage mechanism 42: Shared unit 43: Temperature measurement unit 44: Moisture measurement unit 45: Oxygen concentration measurement unit 51: XY stage 52: Stage drive control unit 61: Detection for temperature measurement Device 73: Detector for infrared absorption measurement 83, 83a, 83b: Visible light detector for oxygen detection 91: Air flow path 92: Light transmissive cover 93: Dry air supply device

Claims (14)

A membrane electrode assembly in which an anode electrode is joined to one side of a solid polymer electrolyte membrane and a cathode electrode is joined to the other side, and an anode side that is electrically connected to the anode electrode and forms a fuel introduction space facing the anode electrode of the membrane electrode assembly A separator and a cathode-side separator that conducts to the cathode electrode and faces the cathode electrode of the membrane electrode assembly to form an oxygen introduction space;
The membrane electrode assembly is sandwiched between the anode side separator and the cathode side separator,
An oxygen monitor substance whose optical characteristics change depending on the oxygen concentration is fixed to any oxygen concentration measurement site in the oxygen introduction space and / or the fuel introduction space,
A light transmitting window made of a light transmitting material is formed on a part of the anode side separator and / or cathode side separator on the side where the oxygen monitor substance is fixed,
A fuel battery cell configured to be capable of optically measuring a change in oxygen monitor substance in the oxygen introduction space or / and in the fuel introduction space through a light transmission window from the outside of the fuel battery cell,
A plurality of types of oxygen monitor substances having different detection wavelength ranges are fixed as oxygen monitor substances at different positions in the oxygen introduction space and / or the fuel introduction space, and the oxygen concentration at each location is measured independently. Fuel cell. A flow path wall that forms an oxygen flow path in the oxygen introduction space and / or a flow path wall that forms a fuel flow path in the fuel introduction space is formed, and the flow path wall is between the cathode electrode and the cathode side separator, The fuel cell according to claim 1, wherein the fuel cell is formed of a conductive material that conducts between the anode-side separator and the anode-side separator. The fuel cell according to claim 2, wherein at least a part of the flow path wall is formed of a light transmissive material, and an oxygen monitor substance is fixed to a surface of the flow path wall. The fuel cell according to claim 3, wherein a transparent conductive film is formed on a flow path wall formed of a light transmissive material. 2. The fuel cell according to claim 1, wherein the oxygen monitor substance is a light-emitting luminescent material whose emission luminescence intensity changes depending on an oxygen concentration, or a color-developing material whose color changes depending on the oxygen concentration. 6. The fuel cell according to claim 5, wherein the oxygen monitor substance is a light emitting luminescence material containing a metal porphyrin or a metal porphyrin complex. 6. The fuel cell according to claim 5, wherein the oxygen monitor substance is a coloring material containing blackened titanium. The fuel cell according to claim 1, wherein a metal film that reflects infrared light is formed on a part of the cathode electrode surface and / or the anode electrode surface. The fuel battery cell according to any one of claims 1 to 8 ,
A photodetector for measuring the optical properties of the oxygen monitor substance;
A fuel cell reaction measuring apparatus comprising: an oxygen measuring optical system for guiding detection light from an oxygen monitor substance to a light detector through a light transmission window. 10. The fuel cell reaction measuring apparatus according to claim 9 , wherein when the oxygen monitor substance is a luminescent material, the oxygen monitor substance is irradiated with excitation light from a light transmission window using an oxygen measurement optical system. A fuel cell according to claim 8;
A photodetector for measuring the optical properties of the oxygen monitor substance;
A fuel cell reaction measurement device comprising an oxygen measurement optical system for guiding detection light from an oxygen monitor substance to a photodetector through a light transmission window,
The light transmission window uses a material that transmits the visible light region and infrared light region, and transmits at least infrared light in the infrared light absorption wavelength region of water, methanol, methanol oxidation intermediate, or carbon dioxide. An infrared absorption measurement optical system that irradiates through a window and guides the reflected light to an infrared detector for measuring an infrared absorption spectrum, and an infrared ray having a wavelength of 5 μm or more due to radiation emitted from a membrane electrode assembly through a light transmission window And at least one of a temperature measurement optical system that guides the temperature to an infrared detector for temperature measurement, along with the oxygen concentration, the red of any one of the water, methanol, methanol oxidation intermediate, and carbon dioxide A fuel cell reaction measuring device that measures either external absorption or temperature, or both.
The oxygen measuring optical system includes an optical system composed of a concave and convex surface mirror, and the infrared absorption measuring optical system, the temperature measuring optical system, or these two measuring optical systems share the optical system portion composed of the concave and convex surface mirror of the oxygen measuring optical system as a common optical system. The fuel cell reaction measuring device according to claim 11 , wherein the fuel cell reaction measuring device is shared as 13. The fuel cell reaction measuring apparatus according to claim 12 , further comprising scanning means for scanning the fuel cell relative to the common optical system. A light transmissive member is attached so as to provide a space outside at least one of the separators of the fuel battery cell, and a temperature adjustment mechanism for supplying a gas for temperature adjustment is provided between the light transmissive member and the separator. 10. The fuel cell reaction measuring device according to claim 9, wherein

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