JP2011198467A - Catalyst electrode, fuel cell, equipment, and manufacturing method of catalyst electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an unstable operation at the time of a temporary high output operation of an electrochemical energy device of a fuel cell.SOLUTION: A catalyst electrode is provided which has a catalyst layer containing an electric conductor carrying a catalyst to promote hydrogen oxidation reaction and a metal hydride with an average particle size of 400 nm or less which has a performance to store hydrogen at a high hydrogen partial pressure and release hydrogen at a low hydrogen partial pressure. A fuel cell 1 which uses this catalyst electrode as a fuel electrode 10 and an equipment using this fuel cell 1 as a power source are provided.

Description

  The present invention relates to a catalyst electrode, a fuel cell, a device, and a method for manufacturing the catalyst electrode.

  A fuel cell is an electrochemical energy device that uses hydrogen or methanol as fuel and extracts energy generated by a chemical reaction with oxygen in the air as electric energy. Such a fuel cell has a higher theoretical energy capacity than a secondary battery such as a Li-ion battery, and is used as a power source for automobiles, a stationary distributed power source for homes and factories, or a power source for portable electronic devices. can do.

  In the fuel cell, for example, hydrogen is supplied to the fuel electrode, and an electrochemical reaction occurs that oxidizes the hydrogen supplied on the fuel electrode side. The hydrogen oxidation reaction is difficult to proceed at a relatively low temperature and is generally promoted by a noble metal catalyst such as platinum (Pt).

  Here, when the fuel cell is used in a low current state, the fuel cell and the air electrode can generate power in a stable state while maintaining a state close to the equilibrium potential. However, when starting up a device that uses a fuel cell as a power source or during high-current output operation, the voltage drops due to overvoltage, and at the same time, the reactants are temporarily supplied to both the fuel electrode and the air electrode. In some cases, an unstable power supply state may be caused by a rapid voltage drop. And there exists a problem that deterioration of a battery is accelerated | stimulated by such unstable battery operation | movement.

  Here, Patent Documents 1 and 2 disclose an electrode containing a metal hydride capable of reversibly storing or releasing hydrogen, and a fuel cell using this electrode as a fuel electrode. Patent Document 2 describes that the particle size of the metal hydride is 0.05 to 1 μm. Further, it is described that, if such a particle size is adopted, the particle size of the metal hydride can be made to be approximately the same as that of the other component particles of the electrode layer, so that it can be easily distributed uniformly in the electrode layer.

JP 2004-111307 A JP 2008-218269 A

  In the case of the techniques described in Patent Documents 1 and 2, the metal hydrides to be applied include those having a relatively large particle size. That is, it includes a configuration in which the surface area of the metal hydride contained in the electrode cannot be made sufficiently large. In such a configuration, the metal hydride cannot occlude and release a sufficient amount of hydrogen, and as a result, the operation of the fuel cell becomes unstable and the deterioration of the cell is promoted.

  In view of such a background, an object of the present invention is to provide a mechanism for improving unstable operation during temporary high-power operation of an electrochemical energy device of a fuel cell.

  According to the present invention, an electric conductor carrying a catalyst for promoting a hydrogen oxidation reaction, and an average particle size of 400 nm or less having the ability to occlude hydrogen under a high hydrogen partial pressure and release hydrogen under a low hydrogen partial pressure. And a catalyst electrode having a catalyst layer containing the metal hydride.

  The present invention also provides a fuel cell using the catalyst electrode as a fuel electrode.

  Moreover, according to this invention, the apparatus which uses the said fuel cell as a motive power source is provided.

  Further, according to the present invention, a diffusion layer preparation step for preparing a diffusion layer, an electric conductor carrying a catalyst for promoting a hydrogen oxidation reaction, occlusion of hydrogen under a high hydrogen partial pressure, and a low hydrogen partial pressure Then, after preparing a mixture in which a metal hydride capable of releasing hydrogen is mixed, a dispersion manufacturing process for dispersing the mixture in a dispersion, and the dispersion in which the mixture is dispersed are added to the first layer of the diffusion layer. There is provided a method for producing a catalyst electrode comprising: a coating drying step of drying after coating on one surface.

  That is, in the present invention, a metal hydride having the capability of occluding hydrogen under a high hydrogen partial pressure and releasing hydrogen under a low hydrogen partial pressure on the catalyst electrode, more specifically, in the catalyst layer of the catalyst electrode. Prepare.

  The catalyst layer is a layer composed of a catalyst that promotes the hydrogen oxidation reaction, and the configuration form is not particularly limited.For example, as described in the following embodiment, the catalyst layer is composed of carbon cloth, carbon paper, or the like. It may be a layer constituted by attaching an electric conductor (carbon particles or the like) carrying a catalyst to the surface of the gas diffusion layer. Or the layer comprised by carrying | supporting a catalyst on the surface of a sheet-like electrical conductor (carbon sheet etc.) may be sufficient.

  The metal hydride of the present invention may adhere to the surface of the catalyst layer as described above, or the same layer as the material of the catalyst or the like as realized by the method of manufacturing the catalyst electrode of the present invention described above. It may be provided above.

  According to the present invention as described above, the metal hydride sufficiently absorbs hydrogen while the hydrogen partial pressure on the fuel electrode (catalyst electrode) is high. On the other hand, the metal hydride releases hydrogen while the hydrogen partial pressure on the fuel electrode (catalyst electrode) is low.

  In the present invention, since the surface area of the metal hydride is sufficiently increased by setting the average particle size of the metal hydride to 400 nm or less, the metal hydride undergoes a stable hydrogen oxidation reaction on the fuel electrode. Therefore, a sufficient amount of hydrogen can be occluded and released. As a result, in the present invention, stable power generation can be continued.

  In the present invention, when the hydrogen partial pressure on the fuel electrode (catalyst electrode) shifts from a low state to a high state, the metal hydride occludes hydrogen again. That is, stabilization of the hydrogen partial pressure on the fuel electrode (catalyst electrode) is realized actively and continuously.

  ADVANTAGE OF THE INVENTION According to this invention, the unstable operation | movement at the time of the temporary high output driving | operation of the electrochemical energy device of a fuel cell can be improved.

It is sectional drawing which shows typically the structure of the fuel cell of this embodiment. It is the current-voltage profile which compared the Example and the comparative example. It is a figure which shows the electrical potential time change at the time of the electric current step which compared the Example and the comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  FIG. 1 is a cross-sectional view schematically showing an example of the fuel cell 1 of the present embodiment. As shown in the figure, the fuel cell 1 of the present embodiment includes a fuel electrode 10, a polymer electrolyte membrane 20, and an air electrode 30.

  First, an outline of the fuel cell 1 of the present embodiment will be described.

  Hydrogen is supplied to the fuel electrode 10 by a hydrogen supply mechanism (not shown), and a hydrogen oxidation reaction occurs on the fuel electrode 10 to generate hydrogen ions and electrons. The polymer electrolyte membrane 20 moves hydrogen ions generated at the fuel electrode 10 to the air electrode 30. In the air electrode 30, hydrogen ions received from the polymer electrolyte membrane 20, electrons moved from the fuel electrode 10 through an external mechanism (not shown), and oxygen (for example, oxygen in the air) react to generate water. .

  Here, the illustrated air electrode 30 includes the catalyst layer 31 and the gas diffusion layer 32 in contact with the catalyst layer 31, but may be configured without the gas diffusion layer 32. In addition, an electrolytic solution having any property of an acidic solution, an alkaline solution, and a neutral solution can be used. That is, in the present embodiment, the configurations of the air electrode 30 and the polymer electrolyte membrane 20 can be any form using conventional techniques. Therefore, the description here is omitted.

  Next, the configuration of the fuel electrode 10 of the present embodiment will be described.

  The fuel electrode 10 has a catalyst layer 11. A hydrogen diffusion layer 12 in contact with the catalyst layer 11 may be further included. The hydrogen diffusion layer 12 can be in any form using conventional technology, and may be composed of, for example, carbon cloth or carbon paper.

  As shown in FIG. 1, the catalyst layer 11 includes an electrical conductor 15 carrying a catalyst 13 and a metal hydride 14. The enlarged view shown in FIG. 1 is an enlarged view of a plane of the catalyst layer 11, that is, a surface in contact with the hydrogen diffusion layer 12.

  The metal hydride 14 has the ability to occlude hydrogen under a high hydrogen partial pressure and release hydrogen under a low hydrogen partial pressure, and the average particle size is 400 nm or less. The average particle size of the metal hydride 14 is preferably 100 nm or less, and more preferably 50 nm or less.

  As such a metal hydride 14, it can be set as the metal hydride shown in either of the following (1) to (4), for example.

(1) Hydride of AB type ₅ alloy (A is rare earth element (La, Pr, Ce, Nd, etc.), unrefined rare earth element (Misch metal; Mm), or X ¹ _n1 X ² _n2 ... X ^m _nm (X ^{1 to} X ^m are rare earth elements, n1 + n2 +... + Nm = 1). B is Ni.),
A hydride in which a part of A in the AB type ₅ alloy is replaced with one or more of Mg, Ca and Ti, or
A hydride obtained by replacing a part of B in the AB type ₅ alloy with one or more of Al, Cr, Mn, and Co.

(2) Hydride of AB type ₂ alloy (A is Ti, Zr, or Ti _n1 Zr _n2 (n1 + n2 = 1). B is Cr, Mn, V, Ni, or Cr _n1 Mn _n2 V _n3 Ni _n4 (n1 + n2 + n3 + n4 = 2)), or
The hydride obtained by replacing a part of B in the AB type ₂ alloy with Co and / or Fe.

(3) AB-type alloy hydride (A is Ti, B is Fe or Co),
A hydride in which part of A in the AB type alloy is replaced by La and / or V, or
A hydride in which part of B in the AB type alloy is replaced with Mn.

(4) A hydride of V or a hydride in which a part of V is replaced by any one or more of Ti, Cr and Mn.

AB ₅ type rare earth · Ni alloy, including LaNi ₅ is an intermetallic compound having the CaCu ₅ type structure of hexagonal, without significantly altering the structure and composition of the host crystal, reversibly store hydrogen ·discharge. Also, the amount of occluded hydrogen changes according to the hydrogen partial pressure, and occludes hydrogen under high hydrogen partial pressure and releases hydrogen under low hydrogen partial pressure. Further, by diversifying the constituent elements of the rare earth element of A, the hydride becomes unstable and the hydrogen dissociation pressure is increased. Further, when a part of Ni in B is replaced with any one or more of Al, Cr, Mn and Co, the hydride is stabilized and the hydrogen dissociation pressure is lowered. Also, the diversification of A and partial substitution of Ni lead to improvement in oxidation resistance and thermal stability.

AB ₂ type alloy represented by TiCr ₂ , ZrCr ₂ , TiMn ₂ , ZrMn ₂ , ZrV ₂ , ZrNi _2, etc. is an intermetallic compound having a hexagonal Laves phase and occludes hydrogen under a high hydrogen partial pressure. Hydrogen can be released under a low hydrogen partial pressure. Moreover, the hydrogen density which can be occluded is high and the capacity can be increased. In addition, the component of A is _multinized as Ti _n1 Zr _n2 (n1 + n2 = 1), the component of B is multinated as Cr _n1 Mn _n2 V _n3 Ni _n4 (n1 + n2 + n3 + n4 = 2), A hydrogen dissociation pressure can be adjusted by using a multicomponent compound in which a part of B is replaced with Co and / or Fe, and can be optimized to a hydrogen dissociation pressure suitable for the application.

  The AB type alloy represented by TiFe, TiCo, etc. is a body-centered cubic intermetallic compound having a relatively large number of voids, which absorbs hydrogen when hydrogen partial pressure is high, and forms a hydride with a higher hydrogen concentration. In a state where the partial pressure is low, hydrogen is released and a hydride having a low hydrogen concentration is formed. In addition, by replacing a part of A with La and / or V and / or a part of B with Mn, the degree of hydrogen dissociation pressure with respect to changes in hydrogen concentration (plateau characteristics) is improved. Suitable for releasing hydrogen at a constant rate.

V reacts efficiently with hydrogen to form hydride (VH ₂ ). The hydrogen density is high and the capacity can be increased. Under normal temperature and near atmospheric pressure, when hydrogen partial pressure is high, hydrogen is absorbed and hydride with higher hydrogen concentration is formed. When hydrogen partial pressure is low, hydrogen is released and hydride with low hydrogen concentration is formed. Is formed. Replacing a part of V with any one or more of Ti, Cr, and Mn can improve the plateau characteristics and release more hydrogen under normal temperature and normal pressure.

  The catalyst 13 and the electrical conductor 15 can be in any form utilizing conventional techniques. For example, the catalyst 13 is not particularly limited as long as it promotes the hydrogen oxidation reaction, and may be a platinum catalyst or a platinum alloy catalyst. Further, the electric conductor 15 may be carbon particles, for example. Further, the means for supporting the catalyst 13 on the electric conductor 15 can be similarly realized using the conventional technique.

  It is desirable that the electric conductor 15 carrying the catalyst 13 and the metal hydride 14 are uniformly dispersed throughout the planar direction of the catalyst layer 11. Further, the content of the metal hydride 14 in the catalyst layer 11 is desirably 20 v% or less.

  Next, the effect of the fuel electrode 10 and the fuel cell 1 of this embodiment is demonstrated using FIG.

  First, consider a case where the operating state of a device using the fuel cell 1 of the present embodiment as a power source is a low current output state that is relatively low. In such a case, since the amount of hydrogen supplied from the hydrogen supply mechanism (not shown) onto the fuel electrode 10 is sufficient for a desired operation, a high hydrogen partial pressure state is maintained on the fuel electrode 10. The In this embodiment, in such a state, the metal hydride 14 sufficiently absorbs hydrogen.

  Next, consider a case where the operating state of a device using the fuel cell 1 of the present embodiment as a power source is a high current output state. In such a case, while the hydrogen supplied from the hydrogen supply mechanism (not shown) to the fuel electrode 10 remains to some extent, the hydrogen oxidation reaction is in a thermodynamic equilibrium state on the catalyst 13 that promotes hydrogen oxidation. It happens in a close state. However, when the supply of hydrogen from a hydrogen supply mechanism (not shown) does not catch up with the consumption of hydrogen on the fuel electrode 10, the voltage starts to decrease and at the same time a low hydrogen partial pressure state is entered. In this embodiment, in such a state, the metal hydride 14 releases hydrogen. Then, the hydrogen oxidation reaction using the released hydrogen is performed on the fuel electrode 10, and as a result, power generation is stably continued.

  In the present embodiment, the surface area of the metal hydride 14 is sufficiently increased by setting the average particle size of the metal hydride 14 to 400 nm or less, preferably 100 nm or less, and more preferably 50 nm or less. Therefore, the metal hydride 14 can occlude and release a sufficient amount of hydrogen so that a stable hydrogen oxidation reaction is performed on the fuel electrode 10. In such a case, stable power generation can be continued.

  In this embodiment, the operation in the high current output state is returned to the operation in the low current output state, and the amount of hydrogen supplied onto the fuel electrode 10 from the hydrogen supply mechanism (not shown) is the desired operation. Therefore, when the amount is sufficient, the fuel electrode 10 is in a high hydrogen partial pressure state, and the metal hydride 14 occludes hydrogen again.

  That is, the effect of compensating for the shortage of hydrogen during high-power operation can be used actively and continuously.

  In the present embodiment, (1) the metal hydride 14 has an average particle diameter of 400 nm or less, preferably 100 nm or less, more preferably 50 nm or less, and (2) an electric conductor 15 carrying the catalyst 13, And a configuration in which the metal hydride 14 is uniformly dispersed throughout the planar direction of the catalyst layer 11 and / or (3) a configuration in which the content of the metal hydride 14 in the catalyst layer 11 is 20 v% or less. Thus, a reduction in the effective area of the catalyst 13 and the electric conductor 15 carrying the catalyst 13 is suppressed, and a configuration in which diffusion of reactive species such as hydrogen is not hindered is realized, and as a result, stable on the fuel electrode 10 is achieved. Hydrogen oxidation reaction can be realized.

  In addition, since the release | releasing and occlusion ability of hydrogen differ with each substance, the substance used for the metal hydride 14 should be selected according to the size of the fuel electrode 10, the operation output of the equipment using the fuel cell 1, and the like. Is possible.

  Further, a heating / cooling mechanism may be added to the fuel electrode 10 in order to control the storage or release speed of hydrogen. In such a case, the fuel electrode 10 containing the metal hydride 14 can be heated in conjunction with the increase in the output current to increase the hydrogen release rate, and conversely, the metal hydride 14 can be coupled with the decrease in the output current. The fuel electrode 10 that is included can be cooled to facilitate the storage of hydrogen.

  According to the fuel cell 1 having the fuel electrode 10 of the present embodiment having such an effect, it is possible to continue stable power generation and to be caused by operating in a low hydrogen partial pressure state. Electrode deterioration can be suppressed.

  Further, in the case of the present embodiment as described above, a device for measuring the hydrogen partial pressure as in the prior art is installed to detect the hydrogen partial pressure, and a space saving can be achieved compared with a means of adding a separate hydrogen supply device. At the same time, there is no need for extra power and cost reduction.

  Here, the manufacturing method of the fuel electrode 10 of the present embodiment is not particularly limited, but may be a manufacturing method including the following steps, for example.

(Diffusion layer preparation process) A diffusion layer (example: carbon cloth, carbon paper, etc.) is prepared.

(Dispersion production process) A particulate electric conductor carrying a catalyst that promotes the hydrogen oxidation reaction, and average particles capable of absorbing hydrogen under a high hydrogen partial pressure and releasing hydrogen under a low hydrogen partial pressure After preparing a mixture in which a metal hydride having a diameter of 400 nm or less is mixed, the mixture is dispersed in a dispersion.

(Coating and drying step) The dispersion liquid in which the mixture is dispersed is applied on the first surface of the diffusion layer and then dried.

  According to such a manufacturing method, it is possible to apply the electric conductor 15 carrying the catalyst 13 and the metal hydride 14 on the first surface of the hydrogen diffusion layer 12 in a sufficiently dispersed state. It becomes. As a result, on the first surface, in part, the effective area of any one or more of the catalyst 13, the electric conductor 15 supporting the catalyst 13, and the metal hydride 14 is effectively suppressed. can do. In addition, the electric conductor 15 carrying the catalyst 13 and the metal hydride 14 can be uniformly dispersed throughout the planar direction of the catalyst layer 11. Here, the dispersion is not particularly limited as long as the mixture can be sufficiently dispersed, and for example, a dispersion of a polymer in the solution may be used. The means for applying the remaining liquid is not particularly limited, and means such as spray coating or roll coater coating may be used.

  In addition, the manufacturing method of the fuel electrode 10 of this embodiment is not limited to the above-described example. For example, after the metal hydride 14 is attached to the first surface of the hydrogen diffusion layer 12, a treatment for attaching the electric conductor 15 carrying the catalyst 13 may be performed thereon. Alternatively, after the electric conductor 15 carrying the catalyst 13 is attached to the first surface of the hydrogen diffusion layer 12, the metal hydride 14 may be attached thereon. In this treatment, for example, after the electric conductor 15 carrying the catalyst 13 is attached to the first surface of the hydrogen diffusion layer 12, the fuel electrode 10, the polymer electrolyte membrane 20, and the air electrode 30 are laminated in this order, For example, a process in which the metal hydride 14 is sandwiched between the fuel electrode 10 and the polymer electrolyte membrane 20 during thermocompression bonding may be used.

  Since the manufacturing method of the fuel cell 1 having the fuel electrode 10 according to the present embodiment can be realized in accordance with the prior art, the description thereof is omitted here.

  Here, the fuel cell 1 having the fuel electrode 10 of the present embodiment can be used as a power source for all devices. For example, it can be used as a power source for automobiles and a power source for portable electronic devices. According to the device using the fuel cell 1 of the present embodiment as a power source, a rapid voltage drop in a high current output state can be suppressed, and a stable operation can be realized. Note that the method of using the fuel cell 1 as a power source and the method of manufacturing the device of the present embodiment can be realized in accordance with the prior art, and thus the description thereof is omitted here.

  Hereinafter, details of the present embodiment will be specifically described in Examples. Note that the present embodiment is not limited to these examples.

<Example 1>
(Synthesis of LaNi ₅ )
La and Ni were weighed in an inert atmosphere so that the atomic ratio La: Ni = 1: 5, and pulverized and mixed in a mortar. Thereafter, argon gas, was fired at 1000 ° C. 48 hours to prepare a LaNi _5. The structure and composition were confirmed by powder X-ray diffraction. The obtained alloy was pulverized to 100 nm or less using a planetary ball mill.

(Manufacture of fuel cells)
1. Production of Fuel Electrode First, as a diffusion layer, carbon black water-repellent with polytetrafluoroethylene (PTFE) dispersion was applied to the surface of a carbon cloth, and a water-repellent treatment was prepared.

Next, the LaNi ₅ alloy produced above was mixed at a rate of 10 wt% with respect to a 50 wt% platinum-supported catalyst (the catalyst support was ketjen black). Subsequently, this mixed powder was mixed with a Nafion solution (polymer content 5% wt, manufactured by Sigma-Aldrich) to prepare a dispersion solution. Thereafter, this dispersion solution was applied to the surface of the diffusion layer subjected to the water repellent treatment and dried to obtain a fuel electrode.

2. Production of Air Electrode First, as a diffusion layer, carbon black repellent with polytetrafluoroethylene (PTFE) dispersion was applied to the surface of a carbon cloth, and a water repellent treatment was prepared.

  Next, a PtCo (1: 1) catalyst (the catalyst carrier is ketjen black) was mixed with a Nafion solution (polymer content 5% wt, manufactured by Sigma Aldrich) to prepare a dispersion solution. Thereafter, this dispersion solution was applied to the surface of the diffusion layer subjected to water repellency treatment and dried to obtain an air electrode.

3. After that, thermocompression bonding is performed with the fuel electrode and air electrode catalyst layers (layers formed by applying the catalyst) inside, and an electrolyte membrane (a Nafion (registered trademark) membrane of about 50 μm thickness, manufactured by DuPont). As a result, a membrane electrode assembly (MEA) was obtained. Further, the MEA was sandwiched between current collectors provided with a gas flow path on a graphite plate to obtain a test battery.

<Comparative Example 1>
A fuel electrode was produced in the same manner as in Example 1 without using the LaNi ₅ alloy. Thereafter, a test battery was produced in the same manner as in Example 1.

<Comparison between Example 1 and Comparative Example 1>
First, the current-voltage profile and the limit current were measured for the test batteries of Example 1 and Comparative Example 1.

  Hydrogen gas was supplied to the fuel electrode as a fuel at a flow rate of 5 ml / s and a hydrogen pressure of 1.1 atm, and oxygen gas was supplied to the air electrode side at a flow rate of 10 ml / s and an oxygen pressure of 1.5 atm. In the power generation test, the open circuit end voltage was measured, and then the current value was gradually increased until the voltage finally became zero (limit current value). The results are shown in FIG.

  As shown in FIG. 2, the current value at which the voltage becomes zero was 3.5 A in Example 1, whereas it was 2.6 A in Comparative Example 1 (see arrow B). Further, the current value at which the voltage becomes 0.3 V was 2.6 A in Example 1, whereas it was 2.2 A in Comparative Example 1 (see arrow A). From the above results, it can be seen that the voltage drop at the time of high current output is suppressed in Example 1 as compared with Comparative Example 1. The comparison at 0.3V is because the voltage is often used during actual power generation.

  Next, the current step (10 mA to 500 mA) was measured for the test batteries of Example 1 and Comparative Example 1, and the recovery time for the hydrogen-deficient state was measured. Specifically, after holding at a current value of 10 mA for 30 minutes, a voltage value profile with respect to the time after the current was instantaneously increased to 500 mA was recorded, and the recovery time of the hydrogen-deficient state was measured. The result is shown in FIG.

  As shown in FIG. 3, the recovery time of Example 1 was about 10 seconds. On the other hand, the recovery time of Comparative Example 1 was about 70 seconds. From the above results, compared with Comparative Example 1, Example 1 can quickly recover from a voltage drop due to methanol deficiency in the vicinity of the catalyst at the time of a rapid current rise, and can improve the unstable power operation and the catalyst internality resulting from methanol deficiency. This has the effect of increasing the durability by reducing the catalyst deterioration caused by the non-uniform voltage distribution.

<Other embodiments>
Compounds as shown in Tables 1 to 4 were synthesized by the same synthesis method as in Example 1, and then a test battery was fabricated using the same method as in Example 1. Then, the current-voltage profile and the limit current were measured for these test batteries by the same means as described above.

  The measurement results are shown in Tables 1 to 4. The current value (A) at point B shown in the table is the current value at which the voltage becomes zero, and the current value (A) at point A is the current value at which the voltage becomes 0.3V. As can be seen from these results, it can be seen that also in the test batteries of other examples, the voltage drop at the time of high current output is suppressed as compared with Comparative Example 1.

  As is apparent from the above results, according to the present invention, it is possible to realize a mechanism that improves unstable operation during temporary high-power operation of the fuel cell.

DESCRIPTION OF SYMBOLS 1 Fuel cell 10 Fuel electrode 11 Catalyst layer 12 Hydrogen diffusion layer 13 Catalyst 14 Metal hydride 15 Electrical conductor 20 Polymer electrolyte membrane 30 Air electrode 31 Catalyst layer 32 Gas diffusion layer

Claims (10)

  An electric conductor carrying a catalyst that promotes a hydrogen oxidation reaction, a metal hydride having an average particle size of 400 nm or less having the ability to occlude hydrogen under a high hydrogen partial pressure and release hydrogen under a low hydrogen partial pressure; The catalyst electrode which has a catalyst layer containing this. The catalyst electrode according to claim 1,
The metal hydride is
Hydride of AB type ₅ alloy (A is rare earth element, unrefined rare earth element (Misch metal; Mm), or X ¹ _n1 X ² _n2 ... X ^m _nm (X ^{1 to} X ^m are rare earth elements, n1 + n2 +... + nm = 1) B is Ni.)
A hydride in which a part of A of the AB type ₅ alloy is replaced by any one or more of Mg, Ca and Ti; or
A catalytic electrode which is a hydride in which a part of B of the AB type ₅ alloy is replaced by any one or more of Al, Cr, Mn and Co. The catalyst electrode according to claim 1,
The metal hydride is
Hydride of AB type ₂ alloy (A is Ti, Zr, or Ti _n1 Zr _n2 (n1 + n2 = 1). B is Cr, Mn, V, Ni, or Cr _n1 Mn _n2 V _n3 Ni _n4 (n1 + n2 + n3 + n4) = 2))) or
A catalytic electrode which is a hydride obtained by replacing a part of B of the AB type ₂ alloy with Co and / or Fe. The catalyst electrode according to claim 1,
The metal hydride is
Hydride of AB type alloy (A is Ti. B is Fe or Co.),
A hydride in which a part of A of the AB type alloy is replaced by La and / or V, or
A catalyst electrode, wherein a part of B of the AB-type alloy is a hydride obtained by replacing Mn with Mn. The catalyst electrode according to claim 1,
The metal hydride is
A catalyst electrode which is a hydride of V or a hydride in which a part of V is replaced by any one or more of Ti, Cr and Mn. The catalyst electrode according to any one of claims 1 to 5,
The catalyst electrode, wherein the content of the metal hydride in the catalyst layer is 20 v% or less. The catalyst electrode according to any one of claims 1 to 6,
A catalyst electrode provided with a hydrogen gas diffusion layer in contact with the catalyst layer.   A fuel cell using the catalyst electrode according to any one of claims 1 to 7 as a fuel electrode.   A device using the fuel cell according to claim 8 as a power source. A diffusion layer preparation step of preparing a diffusion layer;
Creates a mixture of an electrical conductor carrying a catalyst that promotes the hydrogen oxidation reaction and a metal hydride that absorbs hydrogen under high hydrogen partial pressure and releases hydrogen under low hydrogen partial pressure Then, a dispersion manufacturing process for dispersing the mixture in the dispersion,
A coating and drying step of drying the dispersion in which the mixture is dispersed on the first surface of the diffusion layer and then drying;
The manufacturing method of the catalyst electrode which has this.

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