JP2022065582A - Hydrogen gas concentration sensor for fuel cell - Google Patents

Abstract

To provide a hydrogen gas concentration sensor for fuel cell, capable of detecting hydrogen gas in from low concentration to high concentration and excellent in response speed.SOLUTION: The hydrogen gas concentration sensor for fuel cell comprises: a hydrogen gas concentration sensor for low concentration which includes a first electrode and a second electrode, and a first solid electrolyte in contact with the electrodes, the first electrode containing a first electrode material in which reference electromotive force value of the cell composed of H2(-)|50 mol/m3H2SO4| material sample (+) indicates a value of 0.8 V or more, and the second electrode containing a second electrode material in which the reference electromotive force value of the same configured cell indicates a value of less than 0.8 V; and a hydrogen gas concentration sensor for high concentration which includes a third electrode and a fourth electrode, and a second solid electrolyte in contact with the electrodes, the third electrode containing a third electrode material having hydrogen occlusion property, in which the reference electromotive force value of the cell composed of H2(-)|50 mol/m3H2SO4| material sample (+) indicates a value of 0.8 V or more, the fourth electrode containing a fourth electrode material in which the reference electromotive force value of the same configured cell indicates a value of less than 0.8 V.SELECTED DRAWING: Figure 4

Description

The present invention relates to a hydrogen gas concentration sensor for a fuel cell.

In the future hydrogen energy utilization society, it is desired to eliminate the danger of hydrogen explosion and to construct a highly safe and convenient hydrogen energy utilization system. The specifications of the hydrogen gas sensor are required to be able to detect the amount of hydrogen leaked into the atmosphere instantly with high accuracy, have an extremely simple structure, and have high reliability.

Conventional hydrogen gas concentration sensors are based on detection methods such as semiconductor type, ionization type, and combustion type. These measurement principles are "extensive physical quantities" such as "carrier concentration (semiconductor type)", "ion concentration (ionization type)", or "heat of reaction (burning type or burning and measuring its water vapor pressure)". "The amount of hydrogen is detected by an indirect detection method, and they are converted into an electrical quantity to be used as a sensor. Therefore, it took time to detect the hydrogen gas, and it took 100 seconds or more for the slow one. In particular, a hydrogen gas concentration sensor for a fuel cell can detect hydrogen gas in the entire concentration range from low concentration to high concentration, and it is indispensable that the time required for detection is short.

Patent Document 1 discloses a hydrogen gas concentration sensor in which a detection electrode and a reference electrode are appropriately selected from nickel, titanium, copper iron, aluminum, alloys containing these, and organic conductive materials. However, although the hydrogen gas concentration sensor can detect the hydrogen gas concentration under high concentration, it is difficult to detect the hydrogen gas concentration under low concentration. Further, there is a problem that the response time is long and the time required for detection becomes long.

Patent No. 5201593

An object of the present invention is to provide a novel hydrogen gas concentration sensor for a fuel cell capable of detecting hydrogen gas from a low concentration to a high concentration, having an excellent response speed, and shortening the detection time.

The present invention is as shown below.
(1) A first electrode and a second electrode are provided, and a first solid electrolyte that comes into contact with these electrodes is provided, and the first electrode is H ₂ (−) | 50 mol / m ³ H ₂ SO ₄ | Material sample ( The first electrode material having a standard electromotive force value of 0.8 V or more in the cell configured with +) is included, and the second electrode has a standard electromotive force value of less than 0.8 V in the cell having the same configuration. A low-concentration hydrogen gas concentration sensor including a second electrode material indicating a value, a third electrode and a fourth electrode, and a second solid electrolyte in contact with these electrodes are provided, and the third electrode is H ₂ (. -) | 50 mol / m ³ H ₂ SO ₄ | The standard electromotive force value of the cell composed of the substance sample (+) is 0.8 V or more, and the third electrode material having hydrogen absorption property is included. The fourth electrode comprises a high concentration hydrogen gas concentration sensor including a fourth electrode material having a standard electromotive force value of less than 0.8 V in the cell having the same configuration. Hydrogen gas concentration sensor for.
(2) The first electrode material is characterized by containing at least one of platinum, a platinum alloy and a material containing them, and the third electrode is characterized by containing at least one of palladium, a palladium alloy and a material containing them. The hydrogen gas concentration sensor for a fuel cell according to (1).
(3) The second electrode material and the fourth electrode material are nickel, nickel alloys, titanium, titanium alloys, copper, copper alloys, iron, iron alloys, aluminum, aluminum alloys, organic conductive materials, and materials containing these. The hydrogen gas concentration sensor for a fuel cell according to (2), which comprises at least one.
(4) Any of (1) to (3), wherein at least one of the low-concentration hydrogen gas concentration sensor and the high-concentration hydrogen gas concentration sensor is formed on a strip-shaped base material. One of the hydrogen gas concentration sensors for fuel cells.
(5) The low-concentration hydrogen gas concentration sensor is used in an environment where the hydrogen gas concentration is less than 10% by volume, and the high-concentration hydrogen gas concentration sensor is used in an environment where the hydrogen gas concentration is 10% by volume or more. The hydrogen gas concentration sensor for a fuel cell according to any one of (1) to (4), which is characterized by being used.

According to the present invention, it is possible to provide a novel hydrogen gas concentration sensor for a fuel cell that can detect hydrogen gas from a low concentration to a high concentration, has an excellent response speed, and can shorten the detection time.

It is a schematic block diagram of the fuel cell system in an embodiment. It is a schematic block diagram of the hydrogen gas concentration sensor used in the fuel cell system shown in FIG. 1. It is a graph which shows the relationship between the hydrogen gas concentration by the low concentration hydrogen gas sensor in an Example, and an EMF value. It is a graph which shows the relationship between the hydrogen gas concentration and the EMF value by the hydrogen gas sensor for high concentration in an Example.

FIG. 1 is a schematic configuration diagram of a fuel cell system according to the present embodiment, and FIG. 2 is a schematic configuration diagram of a hydrogen gas concentration sensor used in the fuel cell system shown in FIG.

As shown in FIG. 1, the fuel cell 10 of the fuel cell system in the present embodiment has a fuel electrode 11, an air electrode 12, and an electrolyte 13 sandwiched between these electrodes. The fuel cell 10 can be configured from any shape such as a solid polymer fuel cell, a phosphoric acid fuel cell, a molten carbonate fuel cell, a solid oxide fuel cell, and the like. As the fuel electrode 11, the air electrode 12, and the electrolyte 13, appropriate ones can be selected and used.

The fuel cell 10 is arranged inside the case 16, and a low-concentration hydrogen gas sensor 20 is arranged outside the case 16 under a low-concentration hydrogen gas environment, for example, in the discharge pipe 121 of the air electrode 12, and has a high concentration. A high-concentration hydrogen gas sensor 30 and a low-concentration hydrogen gas sensor 20 are arranged inside the case 16 under a hydrogen gas environment, for example, in the discharge pipe 111 of the fuel electrode 11. In this case, the hydrogen gas sensor 30 for altitude and the hydrogen gas sensor 20 for low concentration constitute a hydrogen gas sensor in the entire concentration range.

Reference numeral 122 represents an air introduction pipe to the air pole 12, and reference numeral 112 represents a hydrogen gas introduction pipe to the fuel pole 11.

Further, as long as the low-concentration hydrogen gas sensor 20 and the high-concentration hydrogen gas sensor 30 are in a low-concentration and high-concentration hydrogen gas environment, respectively, their installation locations are not limited to the above-mentioned locations.

As shown in FIG. 2, the low-concentration gas sensor 20 shown in FIG. 1 includes a plate-shaped first electrode 21 and a second electrode 22 provided so as to face each other, and a solid electrolyte 23 is provided between these electrodes. The structure is such that The first electrode 21 functions as a detection electrode for hydrogen gas, and its electrostatic potential changes significantly when it comes into contact with hydrogen gas. The second electrode 22 functions as a reference electrode for hydrogen gas, and its electrostatic potential hardly changes or even if it changes, it is extremely small when it comes into contact with hydrogen gas.

The first electrode 21 can be composed of a first electrode material having a relatively high chemical potential, specifically, a material having a relatively high adsorption activity to hydrogen gas such as platinum and a platinum alloy. be able to. The first electrode 21 may be made of these materials themselves, but these materials can be supported on a predetermined substrate and used. However, it can be used in any embodiment as long as it does not deviate from the scope of the present invention and functions as a detection electrode for hydrogen gas.

The second electrode 22 can be made of a material having a relatively low chemical potential, and specifically, nickel, nickel alloy, titanium, titanium alloy, copper, copper alloy, iron, iron alloy, aluminum, aluminum alloy. It can also be composed of a material having a relatively low degree of adsorption activity for hydrogen gas, such as an organic conductive material. However, it can be used in any embodiment as long as it does not deviate from the scope of the present invention and functions as a reference electrode for hydrogen gas.

The first electrode 21 and the second electrode 22 have a plate shape, and the specific shape thereof can be various shapes such as linear, tubular, disc, and rectangular.

Further, the solid electrolyte 23 can be composed of a solid electrolyte having excellent adhesion to the first electrode 21 and the second electrode 22, such as phosphotungstic acid. The solid electrolyte 23 can include a structural reinforcing material such as glass wool in addition to an electrolyte material such as phosphotungsten. In this case, the strength of the solid electrolyte 23 can be increased, and the adhesion to the electrodes 21 and 22 can be further increased.

On the other hand, the high-concentration hydrogen gas sensor 30 basically takes the same mode as the hydrogen gas sensor shown in FIG. 2, but the third electrode 31 is required to have a hydrogen storage property. That is, in the case of a non-hydrogen storage electrode, for example, an electrode made of platinum or the like described above, when the hydrogen gas concentration at the electrode interface increases, the oxygen concentration at the electrode interface becomes relatively low. As a result, the change in EMF due to the reaction with oxygen becomes smaller, so that the change in EMF in the sensor is canceled out, and the change in EMF becomes smaller even if the hydrogen concentration increases. On the other hand, in the case of a hydrogen storage electrode, the hydrogen existing inside the electrode can maintain the oxygen concentration at the electrode interface in a substantially negligible state, so that the change in the EMF of the sensor can be sufficiently detected as the change in the hydrogen concentration. be able to.

Examples of the electrode material constituting the third electrode 31 include palladium and palladium alloys, Mg2Ni alloys, TiFeNiZi _- based alloys, and the like, but palladium and palladium alloys having relatively high chemical potential are preferable.

Therefore, the hydrogen gas sensor 20 having the first electrode 21 made of platinum or the like is suitable for detecting hydrogen gas under a low concentration, and the hydrogen gas sensor 30 having the third electrode 31 made of palladium or the like has a high concentration. Suitable for detection of hydrogen gas sensor.

The fourth electrode 32 of the high-concentration hydrogen gas sensor 30 can be made of the same material as the second electrode 22 of the low-concentration hydrogen gas sensor 20, and can be used in the same manner. The solid electrolyte 33 of the high-concentration hydrogen gas sensor 30 can also be made of the same material as the solid electrolyte 23 of the low-concentration hydrogen gas sensor, and can be used in the same manner.

According to the embodiment, the first electrode 21 and the second electrode 22 are provided with the first solid electrolyte 23 in contact with these electrodes, and the first electrode 21 is H ₂ (−) | 50 mol / m ³ H ₂ . SO ₄ | Contains the first electrode material having a standard electromotive force value of 0.8 V or more in a cell composed of a material sample (+), and the second electrode 22 has a standard electromotive force value in a cell having the same configuration. A low concentration hydrogen gas concentration sensor containing a second electrode material exhibiting a value of less than 0.8 V, a third electrode 31 and a fourth electrode 32, and a second solid electrolyte 33 in contact with these electrodes are provided. The third electrode 31 has a standard electromotive force value of 0.8 V or more in a cell composed of H ₂ (-) | 50 mol / m ³ H ₂ SO ₄ | substance sample (+), and has a hydrogen absorption property. The fourth electrode 32 contains the third electrode material, and the fourth electrode 32 uses a hydrogen gas concentration sensor for high concentration containing the fourth electrode material showing a standard electromotive force value of less than 0.8 V in the cell having the same configuration. Therefore, the low concentration hydrogen gas sensor is responsible for detecting the hydrogen gas concentration under low concentration, and the high concentration hydrogen gas sensor is responsible for detecting the hydrogen gas concentration under high concentration. Therefore, hydrogen gas from low concentration to high concentration can be detected.

Further, in each of the low-concentration hydrogen gas sensor 20 and the high-concentration hydrogen gas sensor 30, the two electrodes constituting the hydrogen gas sensor are configured to contain materials having different chemical potentials with respect to hydrogen gas, and are relative to each other. The first electrode 21 and the third electrode 31 containing a material having a relatively high chemical potential are used as detection electrodes, and the second electrode 22 and the fourth electrode 32 containing a material having a relatively low chemical potential are used as reference electrodes.

Therefore, even when the hydrogen gas sensor 20 or 30 is arranged in the same atmosphere, when hydrogen gas is contained in the atmosphere, the hydrogen gas sensor generates a predetermined electromotive force between electrodes containing materials having different chemical potentials. become. Therefore, even when the first electrode 21 and the second electrode 22 or the third electrode 31 and the fourth electrode 32 of the hydrogen gas sensor are in the same atmosphere, an electromotive force is generated between these electrodes and it is detected. This makes it possible to detect hydrogen gas in the atmosphere.

Further, according to the hydrogen gas sensors 20 and 30 of the embodiment, since the hydrogen gas concentration is detected based on the chemical potential, the hydrogen gas can be detected instantly.

ここで、Ｆはファラデー定数、ＥはＥＭＦ値、

はそれぞれ金属、水素ガスに対する原子状の水素の化学ポテンシャルである。端子〔I〕、〔II〕は同種の銅線のため電子の電気化学ポテンシャルは、

となる。また、静電ポテンシャルと起電力Ｅとの関係

を用いた。ここで、φIは第１の電極の静電ポテンシャルを表し、φIIは第２の電極の静電ポテンシャルを表す。 The electromotive force between the two electrodes of the hydrogen gas sensors 20 and 30 of the embodiment is generated based on the following relational expression.

Here, F is the Faraday constant, E is the EMF value,

Are the chemical potentials of atomic hydrogen for metals and hydrogen gas, respectively. Since terminals [I] and [II] are copper wires of the same type, the electrochemical potential of electrons is

Will be. Also, the relationship between the electrostatic potential and the electromotive force E

Was used. Here, φI represents the electrostatic potential of the first electrode, and φII represents the electrostatic potential of the second electrode.

In the embodiment, the high and low hydrogen concentration means a low concentration when the concentration of hydrogen gas in the atmosphere is less than 10% by volume, and means a high concentration when the concentration of hydrogen gas in the atmosphere is 10% by volume or more.

(Modification example)
In the modified example, at least one of the low-concentration hydrogen gas sensor 20 and the high-concentration hydrogen gas sensor 30 can be arranged on a strip-shaped insulating base material. Specifically, the film-shaped solid electrolytes 23 and 33 are formed, and the first electrode 21, the third electrode 31, the second electrode 22, and the fourth electrode 32 are provided on the film-like solid electrolytes 23 and 33 so as to be separated from each other. As described above, by arranging the low-concentration hydrogen gas sensor 20 and the high-concentration hydrogen gas sensor 30 on the base material to form an integrated sensor, the sensor can be arranged in a limited space. This can be manufactured by incorporating it into a maintenance / replaceable piping screw or the like.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

The hydrogen gas concentration sensors 20 and 30 shown in FIGS. 1 and 2 were placed in an atmosphere having an environmental temperature of 90 ° C. to −50 ° C. and a humidity of 0% to 100% RH, and a hydrogen gas detection test was carried out. The first electrode 21 of the low-concentration hydrogen gas sensor 20 was made of platinum, and the third electrode 31 of the high-concentration hydrogen gas sensor 30 was made of palladium. Further, both the second electrode 22 and the fourth electrode 32 were made of tungsten.

As a result, as shown in FIG. 3, it was found that when the hydrogen concentration is less than 10% by volume, the low concentration hydrogen gas sensor 20 functions and the EMF value changes, and the hydrogen gas concentration can be detected. Further, as shown in FIG. 4, it was found that when the hydrogen concentration is 10% by volume or more, the high concentration hydrogen gas sensor 30 functions and the EMF value changes, and the hydrogen gas concentration can be detected.

That is, it can be seen that it is possible to provide a novel hydrogen gas concentration sensor for a fuel cell that can detect hydrogen gas from a low concentration to a high concentration, has an excellent response speed, and can shorten the detection time.

Although some embodiments of the present invention have been described above, these embodiments are shown as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

10 Fuel cell 11 Fuel cell 12 Air electrode 13 Electrolyte 16 Case 20 Low concentration hydrogen gas sensor 21 1st electrode 22 2nd electrode 23 1st solid electrolyte 30 High concentration hydrogen gas sensor 31 3rd electrode 32 4th electrode 33 2nd solid Electrolytes

Claims (5)

The first electrode and the second electrode are provided with a first solid electrolyte in contact with these electrodes, and the first electrode is H ₂ (−) | 50 mol / m ³ H ₂ SO ₄ | Material sample (+). The first electrode material having a standard electromotive force value of 0.8 V or more in the configured cell is included, and the second electrode has a standard electromotive force value of less than 0.8 V in the cell having the same configuration. A low-concentration hydrogen gas concentration sensor containing the second electrode material,
The third electrode and the fourth electrode are provided with a second solid electrolyte in contact with these electrodes, and the third electrode is H ₂ (−) | 50 mol / m ³ H ₂ SO ₄ | Material sample (+). The standard electromotive force value of the configured cell shows a value of 0.8 V or more and contains a hydrogen-storing third electrode material, and the fourth electrode has a standard electromotive force value of 0. A hydrogen gas concentration sensor for high concentration containing a fourth electrode material showing a value of less than 8 V, and
A hydrogen gas concentration sensor for a fuel cell, characterized by being equipped with. The first electrode material comprises at least one of platinum, a platinum alloy and a material containing them, and the third electrode comprises a palladium, a palladium alloy and at least one of a material containing them. The hydrogen gas concentration sensor for a fuel cell according to claim 1. The second electrode material and the fourth electrode material include at least one of nickel, nickel alloy, titanium, titanium alloy, copper, copper alloy, iron, iron alloy, aluminum, aluminum alloy and a material containing them. The hydrogen gas concentration sensor for a fuel cell according to claim 2, which is characterized. The invention according to any one of claims 1 to 3, wherein at least one of the low-concentration hydrogen gas concentration sensor and the high-concentration hydrogen gas concentration sensor is formed on a strip-shaped base material. Hydrogen gas concentration sensor for fuel cells. The low-concentration hydrogen gas concentration sensor shall be used in an environment where the hydrogen gas concentration is less than 10% by volume, and the high-concentration hydrogen gas concentration sensor shall be used in an environment where the hydrogen gas concentration is 10% by volume or more. The hydrogen gas concentration sensor for a fuel cell according to any one of claims 1 to 4, wherein the hydrogen gas concentration sensor is characterized.

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