JP2004335448A - Operating method for polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a polymer electrolyte fuel cell with excellent safety by providing a method for easily and surely detecting cross leakage or a micro short circuit due to initial failure or durability deterioration. <P>SOLUTION: In this operating method for the polymer electrolyte fuel cell formed by laminating a plurality of single batteries provided with polymer electrolyte films and pairs of electrodes sandwiching the polymer electrolyte films through conductive separators 2. Electric outputs of the single battery or the single battery group are detected after stopping the supply of fuel gas 70 and oxidizing agent gas 60, and a bad single battery or a bad single battery group is detected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for operating a polymer electrolyte fuel cell used for a portable power supply, a power supply for an electric vehicle, a home cogeneration system, and the like. More specifically, the present invention relates to a method for detecting a defective unit cell or a group of defective unit cells in a fuel cell formed by stacking unit cells.

  A polymer electrolyte fuel cell using a polymer electrolyte membrane electrochemically reacts a fuel gas containing hydrogen with an oxidizing gas containing oxygen, such as air, to simultaneously generate electric power and heat. generate. In this polymer electrolyte fuel cell, a catalyst layer mainly composed of a carbon powder carrying a platinum-based metal catalyst is formed on both sides of a polymer electrolyte membrane that selectively transports hydrogen ions. On the outer surface of the catalyst layer, a diffusion layer having both gas permeability and an electron conductivity for fuel gas and oxidizing gas is formed, and the diffusion layer and the catalyst layer constitute an electrode.

  In order to prevent the supplied fuel gas and oxidizing gas from leaking out and to prevent these two types of gases from mixing with each other, a gas seal material such as a gasket is sandwiched between the electrodes so as to sandwich the polymer electrolyte membrane. Be placed. This gas seal material is assembled integrally with the electrode and the polymer electrolyte membrane. The one obtained by integrating the polymer electrolyte membrane, the electrode, and the gas sealant in this manner is called an MEA (membrane electrode assembly). Outside the MEA, a conductive separator for mechanically fixing the MEA and electrically connecting adjacent MEAs to each other in series is arranged. A gas flow path for supplying a fuel gas or an oxidizing gas to the electrode and carrying away generated gas or surplus gas is formed in a portion of the separator that contacts the MEA. Although the gas flow path can be provided separately from the separator, a method in which a groove is provided on the surface of the separator to form a gas flow path is generally used.

In order to supply the fuel gas or the oxidizing gas to the groove, a through hole is provided in the separator having the gas flow path, and the entrance and exit of the gas flow path are extended to the through hole, and the fuel gas and the oxidizing gas are directly supplied from the through hole. It is necessary to supply the agent gas while branching to each gas flow path. Here, a through hole for supplying a fuel gas or an oxidizing gas to each gas flow path is called a manifold hole.
Further, since a polymer electrolyte fuel cell generates heat during operation, it is necessary to cool the cell using cooling water or the like in order to maintain the cell in a favorable temperature state. Usually, a cooling unit for flowing cooling water for every one to three cells is provided between the separators. Generally, a cooling section is often provided by providing a cooling water flow path on the back surface of the separator. In this case, the separator also needs to be provided with a manifold hole for distributing the cooling water to each cooling water channel.

The MEA, the separator and the cooling unit as described above are alternately stacked, and a laminated body obtained by laminating 10 to 200 unit cells is sandwiched between end plates via a current collecting plate and an insulating plate, and both ends are fastened with fastening bolts. It is common to obtain a polymer electrolyte fuel cell by fixing the fuel cell.
Here, the end plate is provided with inlets for supplying and discharging the fuel gas, the oxidizing gas and the cooling water corresponding to the manifold holes of the fuel gas, the oxidizing gas and the cooling water, respectively. Supply and discharge of these fuel gas, oxidizing gas and cooling water are performed through an inlet.

  However, in the conventional polymer electrolyte fuel cell described above, the fuel gas is supplied to the oxidant gas side electrode (oxidizing gas) due to the initial failure of the polymer electrolyte membrane, the occurrence of pinholes due to the deterioration of durability, and the failure of the gasket. However, there is a problem that a cross leak occurs, in which leakage occurs to the electrode (fuel electrode) or the oxidizing gas leaks to the electrode (fuel electrode) on the fuel gas side. At this time, the leaked fuel gas directly reacts with the oxidizing gas on the catalyst of the electrode on the oxidizing gas side, and if this state is continued for a long time, the pinhole is enlarged by local heat generation due to the reaction. Then, there is a problem in that the fuel gas burns violently and the whole fuel cell may reach a dangerous state.

Further, since the above-mentioned polymer electrolyte fuel cell has a structure in which a thin polymer electrolyte membrane is sandwiched and held via a catalyst layer or a diffusion layer, carbon fiber is applied to the polymer electrolyte membrane in a portion where pressure is locally applied. Was buried, and a micro short could occur. In the area where micro-shorts are occurring, a small amount of current is flowing and does not significantly affect the normal power generation performance, but due to heat generation, it develops into a pinhole over a long period of use, and as described above Problems could occur.
On the other hand, for example, Patent Document 1 discloses a method of detecting a defective defective unit cell, but it cannot be said that it is sufficient to solve the above problem.
JP 2000-58095 A

  Accordingly, the present invention has been made in view of the above-described problems, and provides a method for easily and surely detecting a cross leak or a micro short-circuit caused by an initial failure or durability deterioration. The purpose is to realize battery operation.

In order to solve the above-described problems, the present invention includes a polymer electrolyte membrane, and a pair of electrodes sandwiching the polymer electrolyte membrane, wherein a fuel gas containing hydrogen is supplied to one of the electrodes, and A method for operating a polymer electrolyte fuel cell obtained by stacking a unit cell that generates power by supplying an oxidizing gas containing oxygen to the other of the electrodes via a conductive separator,
After stopping the supply of the fuel gas and the oxidizing gas, an electric output of the unit cell or the unit cell group is detected, and when the electric output is equal to or less than a predetermined value, the unit cell or the unit cell group is determined to be defective. A method for operating a polymer electrolyte fuel cell, comprising a step of determining.

  In the operating method, after the supply of the fuel gas and the oxidizing gas is stopped, an inert gas or a source gas containing methane or propane is supplied to at least one of the pair of electrodes, and the inert gas is supplied. Alternatively, it is preferable to detect an electric output of the unit cell or the unit cell group during the supply of the source gas, and determine that the unit cell or the unit cell group is defective when the electric output is equal to or less than a predetermined value. . It is preferable that the predetermined value is a voltage value at which the metal catalyst in the electrode to which the fuel gas is supplied starts melting.

Further, a change amount of the electric output per unit time may be detected, and when the change amount is equal to or more than a predetermined value, the unit cell or the unit cell group may be determined to be defective.
Further, the present invention includes a polymer electrolyte membrane, and a pair of electrodes sandwiching the polymer electrolyte membrane, wherein one of the electrodes is supplied with a fuel gas containing hydrogen, and the other of the electrodes is an oxidation containing oxygen. A polymer electrolyte fuel cell obtained by stacking a plurality of unit cells that generate electric power by supply of an oxidizing gas through a conductive separator, wherein the supply of the fuel gas and the oxidizing gas is stopped. And after detecting the electric output of the unit cell or the unit cell group, when the electric output is equal to or less than a predetermined value, the control unit determines that the unit cell or the unit cell group is defective. It also relates to a polymer electrolyte fuel cell.

  According to the present invention, in a fuel cell in which unit cells are stacked, if there is a defective unit cell in which a cross leak or a micro short has occurred, the voltage of the defective unit cell after the supply of fuel gas is stopped By focusing on the fact that the voltage decreases extremely quickly as compared with other normal cells, the occurrence of cross leak and micro short-circuit can be easily and reliably detected.

  The present inventors stopped the supply of the fuel gas and the oxidizing gas when the fuel cell obtained by stacking the unit cells had a defective unit cell in which a cross leak or a micro short circuit occurred. Paying attention to the fact that the voltage of the defective unit cell drops extremely quickly compared to other normal unit cells, a polymer electrolyte fuel cell that can reliably detect the occurrence of cross leak and micro short circuit I found a driving method.

  That is, the present invention includes a polymer electrolyte membrane, and a pair of electrodes sandwiching the polymer electrolyte membrane, wherein one of the electrodes is supplied with a fuel gas containing hydrogen, and the other of the electrodes is an oxidation containing oxygen. A method for operating a polymer electrolyte fuel cell obtained by stacking unit cells that generate electric power by supply of an oxidant gas through a conductive separator, wherein the supply of the fuel gas and the oxidant gas is performed. After stopping, an electric output of the unit cell or unit group is detected, and a defective unit cell or unit group in the fuel cell is detected.

Here, the point of the present invention is that, in a fuel cell formed by stacking unit cells, by detecting the voltage, current or the amount of change in the unit cell or unit group, a defective unit cell or unit group is detected. And there is no particular limitation on the configuration of the unit cell. There is no particular limitation on the number of cells included in the cell group.
In the step, after the supply of the fuel gas is stopped, an inert gas or the like is supplied instead of the fuel gas, and a voltage or the like of the unit cell during the supply of the inert gas is detected. It is preferable to detect a defective unit cell in. This is due to the fact that the consumption rate of remaining hydrogen and oxygen is higher in cells having cross leaks and micro-shorts than in normal cells, and it is difficult to recognize small cells during normal operation. This is because even a large leak or short circuit can be detected.

Examples of the inert gas include a nitrogen gas, an argon gas, a helium gas, and the like. Among them, it is preferable to use a nitrogen gas because it can be obtained relatively easily.
In addition, the supply amount of the inert gas at this time may be in the range of 5 to 30 liters / minute, but the flow rate at which the rated pressure loss is achieved is because the pressure applied to the MEA in the operating state is limited. preferable.

  Further, it is preferable that a defective unit cell in the fuel cell is detected by detecting that a voltage value of the unit cell is equal to or less than a preset voltage value. That is, the voltage value of the unit cell at the time when a predetermined time (predetermined time) has elapsed from the stop of the supply of the fuel gas and the oxidizing gas or the start of the supply of the inert gas is set to a predetermined threshold value. It is effective to detect that the fuel cell is equal to or less than a (predetermined value) to detect a defective unit cell of the fuel cell. This is because cells with cross-leak and micro-short problems have a sharp drop in voltage, and the difference from normal cells is particularly noticeable during certain periods of time. is there. The preferred predetermined time and threshold value will be described in an embodiment described later.

  In addition, the inert gas may be supplied to both the fuel electrode and the oxidant electrode in the unit cell constituting the fuel cell, or may be supplied only to the fuel electrode. Moreover, you may supply only to an oxidizer electrode. Above all, from the viewpoint of safety, in the actual system, when the fuel cell is shut down, the fuel electrode is always purged with an inert gas. Is preferred.

As a voltage detection method, a multi-channel data logger, a multi-channel AD conversion board, or the like can be used. Examples of the multi-channel data logger include Agilent 34970A, and examples of the multi-channel A / D conversion board include NA98-0164 manufactured by NATEC. Further, the detected voltage value is taken into a control computer (control unit) and compared with a threshold value set and stored in advance on the computer.
Hereinafter, the present invention will be described more specifically with reference to the drawings using examples, but the present invention is not limited thereto.

<< Example 1 >>
First, a first catalyst (50) in which platinum particles having an average particle size of about 30 ° are supported on Ketjen Black EC (manufactured by AKZO Chemie, the Netherlands) which is conductive carbon particles having an average primary particle size of 30 nm. Wt% platinum) was used as the catalyst on the oxidant electrode side. A second catalyst (25 wt% platinum, 25 wt% ruthenium) in which Ketjen Black EC carries platinum particles and ruthenium particles having an average particle size of about 30 ° was used as a catalyst for the fuel electrode.

A dispersion obtained by dispersing the first catalyst in isopropanol and a dispersion in which a powder of perfluorocarbon sulfonic acid was dispersed in ethyl alcohol were mixed to obtain a first paste. By a screen printing method, the first paste was applied to one surface of a carbon nonwoven fabric having a thickness of 250 μm to form a catalyst layer, thereby producing an electrode (oxidant electrode). Incidentally, amount of platinum contained in the catalyst layer after electrode fabrication is 0.5 mg / cm ^2, the amount of perfluorocarbon sulfonic acid was adjusted to be 1.2 mg / cm ^2.

Similarly, a dispersion obtained by dispersing the second catalyst body in isopropanol and a dispersion in which perfluorocarbon sulfonic acid powder was dispersed in ethyl alcohol were mixed to obtain a second paste. . By a screen printing method, a second paste was applied to one surface of a carbon nonwoven fabric having a thickness of 250 μm to form a catalyst layer, thereby producing an electrode (fuel electrode). Again, the amount of platinum contained in the catalyst layer after electrode fabrication is 0.5 mg / cm ^2, the amount of perfluorocarbon sulfonic acid was adjusted to be 1.2 mg / cm ^2.

  Next, the catalyst layer and the polymer electrolyte membrane are sandwiched between the prepared fuel electrode and the oxidizer electrode by sandwiching the center of the proton conductive polymer electrolyte membrane having an area slightly larger than the fuel electrode and the oxidizer electrode. The whole was joined by hot pressing so as to sufficiently adhere. Here, a thin film of perfluorocarbonsulfonic acid (Nafion 112, manufactured by DuPont, USA) was used as the proton conductive polymer electrolyte. Further, a gasket punched in the same shape as a separator to be described later is joined by hot pressing so as to sandwich a portion of the polymer electrolyte membrane located on an outer portion of the fuel electrode and the oxidant electrode from both sides. (Joined body).

  Here, the structure of the polymer electrolyte fuel cell manufactured in this example is shown in FIG. As shown in FIG. 1, a polymer electrolyte fuel cell 10 has a MEA 1 and a separator 2 alternately stacked to obtain a stacked battery, and both ends thereof are connected to an end plate 5 via a current collecting plate 3 and an insulating plate 4. It was pinched and the whole was tightened with a predetermined load to obtain. The end plate 5 has an oxidant gas manifold hole inlet 6 and a fuel gas manifold hole inlet 7 for supplying an oxidant gas 60 and a fuel gas 70 from an external gas supply device (not shown), respectively. Further, an oxidizing gas manifold outlet 8 and a fuel gas manifold outlet 9 from which the oxidizing gas 60 and the fuel gas 70 are discharged, respectively, are provided. These inlet and outlet portions were tubular.

FIG. 2 shows a top view of the separator 2 used in this embodiment. The separator 2 has an inlet manifold hole 21 through which gas supplied from the oxidizing gas manifold hole inlet 6 or the fuel gas manifold hole inlet 7 shown in FIG. 1 flows, and a gas flow branched from the inlet manifold hole 21. A passage 22 and an outlet manifold hole 23 through which the gas flowing through the gas passage 22 is discharged are provided. Also, a manifold hole 24 for cooling water was provided.
In this example, a fuel cell was formed by stacking 50 of the above-described unit cells.

Next, the operation of the polymer electrolyte fuel cell of this example and the voltage behavior after stopping the supply of the fuel gas and the oxidizing gas were measured, and the results are shown in FIG. Here, a simulated reformed gas (containing 80% by volume of hydrogen, 20% by volume of carbon dioxide and 50 ppm of carbon monoxide) was used as a fuel gas, and air was used as an oxidizing gas. The conditions of a hydrogen utilization rate of 80%, an oxygen utilization rate of 50%, a hydrogen humidification bubbler temperature of 75 ° C., an air humidification bubbler temperature of 50 ° C., a battery temperature of 75 ° C., and a current density of 0.3 A / cm ² were used.

  First, after operating the fuel cell under the conditions described above, the load was stopped to stop the supply of the fuel gas and the oxidizing gas, and the inlet and outlet of the manifold holes for the fuel gas and the oxidizing gas were sealed. . FIG. 3 is a graph showing how the voltage of the fuel cell drops at this time. FIG. 3 shows the average voltage of a normal cell and the voltage of a cell having a cross leak. In the state where the load current is stopped, each cell shows an open circuit voltage, but the voltage starts to gradually decrease from the time when the supply of hydrogen is stopped and the outlet and the inlet are sealed, and the voltage decreases to 0 in about 20 minutes. .1V.

  From FIG. 3, it can be seen that the cell having a pinhole clearly has a lowering rate than the average voltage of a normal cell. This is because the cross leak between the fuel gas and the oxidizing gas has occurred in the pinhole portion, and the consumption of the fuel gas remaining near the MEA is promoted. This result is the same for a unit cell in which a micro short circuit has occurred. In this case as well, it is considered that the consumption of residual hydrogen by a minute current is promoted.

  Therefore, by detecting the rate of decrease in the voltage of the unit cell after the supply of the fuel gas and the oxidizing gas is stopped, it is possible to easily and reliably detect the occurrence of the cross leak or the micro short circuit. After the supply of the fuel gas was stopped, a cell having a voltage value equal to or less than a predetermined value at the time when a predetermined time had elapsed was determined to have a pinhole or a micro short circuit.

  FIG. 4 is a graph showing the relationship between the difference between the average voltage of a normal cell and the voltage of a cell having a pinhole, and time. In order to detect a cell having a pinhole with higher accuracy, it is desirable to make a determination in a time zone in which the voltage difference from a normal cell is large. From FIG. 4, it can be seen that the voltage difference increases most about 5 minutes after the supply of the fuel gas is stopped.

  Therefore, in the present embodiment, a voltage value of 0.4 V is set as a threshold value (predetermined predetermined value) of the electric output 5 minutes after the supply of the fuel gas and the oxidizing gas is stopped. Judging from the voltage behavior in FIGS. 3 and 4, the predetermined time is desirably between 2 minutes and 7 minutes, and the predetermined value of the voltage is desirably set between 0.7V and 0.2V. This is because in these ranges, the difference between the normal voltage and the abnormal voltage tends to be clearly detected.

  In response to such a detection result of the pinhole-generating unit cells, the actual cogeneration system can generate an alarm and notify the user of the maintenance time. Further, in this embodiment, the operation method of the fuel cell during the actual operation is shown, but this method is also effective as a shipping inspection immediately after the cell assembly.

<< Example 2 >>
FIG. 5 shows the voltage behavior of the cell voltage of the polymer electrolyte fuel cell of this example. In the present embodiment, a fuel cell similar to the fuel cell used in Embodiment 1 is used, and after the supply of the fuel gas and the oxidizing gas to the fuel cell is stopped, nitrogen gas is supplied to the fuel electrode side as an inert gas. did. FIG. 5 shows the voltage behavior of a unit cell having cross leak and the behavior of the average voltage of a normal unit cell as in Example 1.

  From FIG. 5, it is found that the voltage of each unit cell is rapidly reduced as compared with the case where the nitrogen gas is not supplied, and is reduced to 0.1 V or less within 10 minutes. That is, it is understood that the voltage drop is promoted by forcibly discharging hydrogen by the nitrogen gas. This makes it possible to detect a unit cell in which a cross leak or a pinhole has occurred in about 時間 of the time when no nitrogen gas is supplied.

  FIG. 6 is a graph showing the relationship between the difference between the average voltage of a normal cell and the voltage of a cell having a pinhole, and time. FIG. 6 shows that the voltage difference becomes maximum about 2 minutes after the start of the supply of the nitrogen gas. Therefore, in this embodiment, the threshold value is set to a voltage value of 0.4 V two minutes after the start of the supply of the nitrogen gas. Further, judging from the voltage behaviors shown in FIGS. 5 and 6, the predetermined time is desirably between 1 minute and 4 minutes, and the threshold value of the voltage is desirably set between 0.6 V and 0.2 V.

FIG. 7 shows the voltage behavior when city gas (13A) containing methane gas as a main component is supplied to the fuel electrode after the supply of the fuel gas and the oxidizing gas is stopped, and FIG. The voltage behavior when nitrogen gas was supplied to the oxidant electrode after the supply of fuel gas and oxidant gas was stopped was shown. FIG. 9 shows the voltage behavior when the city gas is supplied to the oxidant electrode after the supply of the fuel gas and the oxidant gas is stopped.
Further, FIG. 10 shows the voltage behavior when propane gas is supplied to the oxidant electrode after the supply of fuel gas and oxidant gas is stopped, and FIG. 11 shows the supply of fuel gas and oxidant gas. After stopping the operation, the behavior of the voltage when propane gas was supplied to the fuel electrode was shown. These behaviors were the same as in Example 2 above. Here, as the inert gas, a helium gas or an argon gas can be used in addition to the nitrogen gas.
Similar results were obtained even when there was a cell having a micro-short, indicating that the method according to the present invention is also effective for detecting a cell having a micro-short. Was.

<< Example 3 >>
FIG. 12 shows the voltage behavior of the polymer electrolyte fuel cell of this example. In this embodiment, a fuel cell similar to the fuel cell used in Embodiment 1 is used, and after the supply of the fuel gas and the oxidizing gas to the fuel cell is stopped, nitrogen gas is supplied to the fuel electrode side as an inert gas. did. FIG. 12 shows a change amount (dV / dT) of the voltage of the unit cell with respect to time in this case. Specifically, the amount of voltage change every 30 seconds is shown.
As can be seen from FIG. 12, the amount of change in the voltage of the defective unit cell is clearly larger than the amount of change in the voltage of the normal unit cell. That is, by detecting the amount of change in voltage per unit time, it is possible to detect a unit cell in which a pinhole or a micro short has occurred.

<< Example 4 >>
In this embodiment, a fuel cell similar to the fuel cell used in Embodiment 1 is used, and after the supply of the fuel gas and the oxidizing gas to the fuel cell is stopped, nitrogen gas is supplied to the fuel electrode side as an inert gas. did. When the voltage of the unit cell in this case became equal to or less than a predetermined value, the unit cell was determined to be defective. Then, the predetermined value was examined.
Normally, the voltage of the fuel cell is the difference between the absolute potential of the fuel electrode and the absolute potential of the oxidant electrode. When no current is generated, the potential of the fuel electrode is about 0 V, and the potential of the oxidant electrode is about 1V. On the other hand, after the supply of fuel gas to the fuel cell is stopped, or after the supply of inert gas or city gas to the fuel electrode side is started, the voltage of the battery decreases because the potential of the fuel electrode increases. This is because the potential of the oxidizer approaches the potential of the oxidant electrode.

Here, it is known that when the potential of the fuel electrode rises and reaches about 0.5 V or more, for example, ruthenium, which is a metal catalyst used in the fuel electrode, starts to elute. That is, it is understood that when the potential of the fuel electrode increases and the battery voltage decreases to less than 0.5 V, the catalyst may be deteriorated.
For this reason, in order to detect a defective cell having a pinhole or a micro-short without damaging a normal cell, the threshold value of the voltage for determining whether or not the cell is defective is determined. It has been found that it is preferable to set the voltage to 0.5 V or more.

  According to the present invention, in a fuel cell in which unit cells are stacked, when there is a defective unit cell in which a cross leak or a micro short circuit has occurred, the voltage of the defective unit cell after the supply of fuel gas is stopped By focusing on the fact that the voltage decreases extremely quickly as compared with other normal cells, the occurrence of cross leak and micro short-circuit can be easily and reliably detected. As a result, the cogeneration system can generate an alarm, notify the user of the maintenance time, and greatly improve the safety in the actual use state. Further, the method according to the present invention can be effectively used as a method for inspecting a fuel cell at the time of product shipment.

FIG. 1 is a diagram showing a configuration of a polymer electrolyte fuel cell manufactured in an example of the present invention. FIG. 2 is a top view illustrating a configuration of a separator used in an example of the present invention. FIG. 2 is a diagram illustrating a voltage behavior of the polymer electrolyte fuel cell in the first embodiment of the present invention. FIG. 4 is a diagram showing a behavior of a voltage difference between a normal cell of the polymer electrolyte fuel cell of Example 1 of the present invention and a cell having a pinhole. FIG. 6 is a diagram illustrating a voltage behavior of a polymer electrolyte fuel cell in Example 2 of the present invention. It is a figure which shows the voltage behavior of the normal cell of the polymer electrolyte fuel cell of Example 2 of this invention, and the cell which generated the pinhole. FIG. 3 is another diagram showing voltage behaviors of a normal cell of the polymer electrolyte fuel cell of the present invention and a cell having a pinhole. FIG. 3 is another diagram showing voltage behaviors of a normal cell of the polymer electrolyte fuel cell of the present invention and a cell having a pinhole. FIG. 3 is another diagram showing voltage behaviors of a normal cell of the polymer electrolyte fuel cell of the present invention and a cell having a pinhole. FIG. 3 is another diagram showing voltage behaviors of a normal cell of the polymer electrolyte fuel cell of the present invention and a cell having a pinhole. FIG. 3 is another diagram showing voltage behaviors of a normal cell of the polymer electrolyte fuel cell of the present invention and a cell having a pinhole. FIG. 3 is another diagram showing voltage behaviors of a normal cell of the polymer electrolyte fuel cell of the present invention and a cell having a pinhole.

Explanation of reference numerals

1 MEA
2 Separator 3 Current collector 4 Insulating plate 5 End plate 6 Manifold hole inlet for oxidizing gas 7 Manifold hole inlet for fuel gas 8 Manifold hole outlet for oxidizing gas 9 Manifold hole outlet for fuel gas 10 Polymer electrolyte Type fuel cell 21 Inlet manifold hole 22 Gas flow path 23 Outlet manifold hole 60 Oxidant gas 70 Fuel gas

Claims (5)

A polymer electrolyte membrane, comprising a pair of electrodes sandwiching the polymer electrolyte membrane, a fuel gas containing hydrogen is supplied to one of the electrodes, and an oxidant gas containing oxygen is supplied to the other of the electrodes A method for operating a polymer electrolyte fuel cell obtained by stacking a plurality of unit cells that generate power by interposing a conductive separator therebetween,
After stopping the supply of the fuel gas and the oxidizing gas, an electric output of the single cell or the single cell group is detected, and if the electric output is equal to or less than a predetermined value, the single cell or the single cell group is defective. A method for operating a polymer electrolyte fuel cell, comprising the step of determining   After the supply of the fuel gas and the oxidizing gas is stopped, an inert gas or a source gas containing methane or propane is supplied to at least one of the pair of electrodes, and the supply of the inert gas or the source gas is performed. 2. The electric output of the unit cell or the unit cell group is detected during the operation, and when the electric output is equal to or less than a predetermined value, the unit cell or the unit cell group is determined to be defective. For operating a polymer electrolyte fuel cell.   The amount of change in the electric output per unit time is detected, and when the amount of change is equal to or more than a predetermined value, the unit cell or the unit cell group is determined to be defective. A method for operating a polymer electrolyte fuel cell.   The method according to claim 1, wherein the predetermined value is a voltage value at which the metal catalyst in the electrode to which the fuel gas is supplied starts melting. A polymer electrolyte membrane, comprising a pair of electrodes sandwiching the polymer electrolyte membrane, a fuel gas containing hydrogen is supplied to one of the electrodes, and an oxidant gas containing oxygen is supplied to the other of the electrodes A polymer electrolyte fuel cell obtained by stacking a plurality of unit cells that generate electric power by way of a conductive separator,
Further, after the supply of the fuel gas and the oxidizing gas is stopped, an electric output of the single cell or the single cell group is detected. When the electric output is equal to or less than a predetermined value, the single cell or the single cell group is detected. A polymer electrolyte fuel cell, comprising: a control unit for determining that a battery is defective.

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