JP5073446B2 - Aging apparatus and operation method for polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to an aging apparatus and operating method for a polymer electrolyte fuel cell having an electrolyte membrane / electrode structure in which an anode electrode and a cathode electrode are disposed on both sides of an electrolyte membrane.

  A fuel cell supplies a fuel gas (mainly hydrogen-containing gas) and an oxidant gas (mainly oxygen-containing gas) to the anode-side electrode and the cathode-side electrode and causes them to react electrochemically. It is a system that obtains electrical energy.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) provided with an anode electrode and a cathode electrode on both sides of an electrolyte membrane made of a polymer ion exchange membrane is sandwiched by separators. Has a cell. This type of power generation cell is normally used as a fuel cell stack mounted on a vehicle such as an automobile, for example, by laminating a predetermined number of electrolyte membrane / electrode structures and separators.

  In this type of polymer electrolyte fuel cell, the initial power generation performance is low because the water content of the electrolyte membrane immediately after assembly is not sufficient. Therefore, usually, the aging operation of the fuel cell is performed in order to obtain a desired power generation performance after the assembly of the fuel cell.

  For example, in the method of operating a fuel cell disclosed in Patent Document 1, the utilization rate of consumed gas is set so that flooding occurs in the fuel cell when the fuel cell is preliminarily operated (aging operation). It is characterized by improving.

  However, in the above operating method, since rapid flooding is involved, the control for suppressing the deterioration of the battery performance becomes complicated, and in particular, the performance of the electrolyte membrane constituting the MEA may be adversely affected.

  Further, when a hydrocarbon material, for example, is used as the electrolyte membrane constituting the MEA instead of the fluorine-based material, the hydrophobicity is higher than that of the fluorine-based material, and water sufficiently penetrates into the electrolyte membrane. There is a problem that it takes time to make it happen.

  Therefore, in the solid polymer fuel cell aging device disclosed in Patent Document 2, a loader that consumes a load current from the polymer electrolyte fuel cell during preliminary operation, the polymer electrolyte fuel cell, Control means connected between the loader and periodically changing the magnitude of the load current with time.

  Thereby, since the magnitude | size of load current is fluctuate | varied periodically with progress of time, the penetration | invasion promotion effect of the water to MEA increases, and it is supposed that the time required for an aging driving | operation can be shortened.

JP 2003-217622 A JP 2007-66666 A

  In the above-mentioned Patent Document 2, the cathode gas is supplied to the cathode, the anode gas is supplied to the anode, and a load current whose magnitude varies periodically with the passage of time from the fuel cell stack to the loader is supplied. Aging operation has started.

  However, the MEA that is used for the first time after assembly cannot generate power with a high current density. For this reason, it is necessary to gradually increase the amount of applied current from a low current density or shorten the holding time during load application to return to OCV (open circuit voltage).

  As a result, a considerable time is required until the power generation performance of the fuel cell is saturated, and there is a problem that it takes time for the aging operation. Moreover, during the aging operation, the cathode gas and the anode gas are consumed, and there is a problem that the amount of hydrogen used is excessive and extremely uneconomical.

  The present invention solves this type of problem, and is a solid polymer fuel cell capable of performing aging treatment satisfactorily in a short period of time while preventing hydrogen consumption as much as possible and performing economic aging. An object of the present invention is to provide an aging device and an operation method.

  The present invention relates to an aging apparatus and an operating method for aging a polymer electrolyte fuel cell having an electrolyte membrane / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte membrane.

An aging apparatus comprises a stack arrangement portion in which a plurality of fuel cell stacks having one or more polymer electrolyte fuel cells are arranged, a power supply portion for applying a potential to the fuel cell stack, and an oxidant gas on one electrode side of inactivity the supply of the power supply unit when it is driven, and a hydrogen supply unit for performing hydrogen pump operation to supply hydrogen humidified to the electrode side of the other lateral.

  The hydrogen supply unit is configured such that after the hydrogen supplied to the other electrode side of the upstream fuel cell stack passes through the electrolyte membrane and is transferred to the one electrode side, the hydrogen is supplied to the downstream fuel cell. A serial supply path is provided to supply the other electrode side of the stack.

  The hydrogen supply section preferably has a circulation path for returning hydrogen discharged from one electrode side of the most downstream fuel cell stack to the other electrode side of the most upstream fuel cell stack.

  Furthermore, it is preferable that a hydrogen storage tank for storing hydrogen is disposed in the circulation path.

  Furthermore, it is preferable that the hydrogen supply unit is provided upstream of the most upstream fuel cell stack and includes a humidifier for humidifying hydrogen.

  Further, it is preferable that the power supply unit electrically connects the upstream fuel cell stack and the downstream fuel cell stack in series.

  Furthermore, the electrolyte membrane is preferably composed of a hydrocarbon-based electrolyte membrane.

  Furthermore, it is preferable that the power supply unit applies a negative electrode potential to the cathode, which is one electrode, and applies a positive electrode potential to the anode, which is the other electrode.

  In addition, the operation method includes preparing a fuel cell stack having one or more polymer electrolyte fuel cells, arranging a plurality of the fuel cell stacks, and applying a potential to the fuel cell stack, And an aging step of performing a hydrogen pump operation for supplying humidified hydrogen to the other electrode side without supplying the oxidant gas to the other electrode side.

  In the aging process, hydrogen supplied to the other electrode side of the upstream fuel cell stack passes through the electrolyte membrane and is transferred to the one electrode side, and then the hydrogen is transferred to the downstream fuel cell stack. It is supplied to the other electrode side.

  In the present invention, since an aging process is performed by a so-called hydrogen pump operation in which a voltage is applied from the outside to move hydrogen ions in the electrolyte membrane, only hydrogen with less overvoltage is involved in the reaction, and the corrosion potential is lower than Can continuously apply a large current (maximum current density in use). Therefore, it is possible to easily suppress the performance deterioration and shorten the time. Moreover, in the hydrogen pump operation, the hydrogen transferred to the cathode side does not react with the oxidant gas. For this reason, hydrogen is not consumed during an aging process, and it is very economical.

  Further, hydrogen discharged from one electrode side of the upstream fuel cell stack is supplied to the other electrode side of the downstream fuel cell stack. Thereby, since hydrogen is efficiently reused, the amount of hydrogen supplied from the outside is favorably reduced, which is economical.

  FIG. 1 is a schematic configuration diagram of an aging device 12 for performing an aging process by a hydrogen pump operation to which the operation method of the polymer electrolyte fuel cell 10 according to the first embodiment of the present invention is applied.

The aging device 12 includes a stack placement portion 16 in which a plurality (three in FIG. 1) of fuel cell stacks 14 a to 14 c having one or more fuel cells 10 are disposed, and a positive electrode on the anode side of the fuel cell 10. A power source 18 that applies a potential and applies a negative potential to the cathode side of the fuel cell 10, and the power source 18 is driven without supplying an oxidant gas to the cathode side. , and a hydrogen supply unit 20 for performing the hydrogen pump operation to supply hydrogen humidified before Symbol anode side.

  As shown in FIG. 2, the fuel cell 10 includes, for example, an electrolyte membrane / electrode structure 30 in which a hydrocarbon-based solid polymer electrolyte membrane 24 is sandwiched between an anode-side electrode 26 and a cathode-side electrode 28, and the electrolyte The membrane / electrode structure 30 is sandwiched between the anode side separator 32 and the cathode side separator 34. The anode side separator 32 and the cathode side separator 34 are made of a carbon plate or a metal plate, and are provided with a seal member (not shown). The solid polymer electrolyte membrane 24 may be a fluorine-based membrane such as perfluorocarbon, for example.

  A fuel gas flow path 36 is formed between the electrolyte membrane / electrode structure 30 and the anode side separator 32, and an oxidant is interposed between the electrolyte membrane / electrode structure 30 and the cathode side separator 34. A gas flow path 38 is formed.

  As shown in FIG. 3, the fuel cell 10 has a fuel gas inlet communication hole 40a for supplying a fuel gas such as a hydrogen-containing gas, and an oxidant for supplying an oxidant gas such as air (oxygen-containing gas). An agent gas inlet communication hole 42a, a fuel gas outlet communication hole 40b for discharging the fuel gas, and an oxidant gas outlet communication hole 42b for discharging the oxidant gas are formed. The fuel gas inlet communication hole 40 a and the fuel gas outlet communication hole 40 b communicate with the fuel gas flow path 36, while the oxidant gas inlet communication hole 42 a and the oxidant gas outlet communication hole 42 b communicate with the oxidant gas flow path 38. To do.

  Each of the fuel cell stacks 14a to 14c has a predetermined number of fuel cells 10. For example, the fuel cell stacks 14a to 14c include one fuel cell 10, several tens of fuel cells 10, or several hundred (equipped) fuel cells 10. Is done.

  As shown in FIGS. 1 and 2, end plates 44 a and 44 b are disposed at both ends of the fuel cell 10 in the stacking direction. Although not shown, the end plates 44a and 44b are integrally held by hydraulic fastening, bolt fastening, a box structure, or the like. The anode terminal 46a protrudes outward from the end plate 44a, while the cathode terminal 46b protrudes outward from the end plate 44b.

  The power supply unit 18 electrically connects the upstream fuel cell stack 14a to the downstream fuel cell stack 14c in series. Specifically, as shown in FIG. 1, the power supply unit 18 includes a DC power supply 48, and the positive pole of the DC power supply 48 is electrically connected to the anode terminal 46a of the most upstream fuel cell stack 14a via the cable 50a. Connected. The negative pole of the DC power supply 48 is electrically connected to the cathode terminal 46b of the most downstream fuel cell stack 14c via the cable 50b. In addition, when the fuel cell stack 14a to the fuel cell stack 14c are connected in series, it is preferable that the fuel cell stack 14a to the fuel cell stack 14c are configured by the same stack in order to make the current density of the electrodes the same.

  The cathode terminal 46b of the fuel cell stack 14a and the anode terminal 46a of the fuel cell stack 14b are electrically connected by a connection cable 52a, and the cathode terminal 46b of the fuel cell stack 14b and the anode terminal 46a of the fuel cell stack 14c. Are electrically connected by a connection cable 52b. The DC power supply 48 is controlled by the controller 54, and the controller 54 controls the entire aging device 12.

  The hydrogen supply unit 20 has an anode supply pipe 58 in which the humidifier 56 is disposed, and the anode supply pipe 58 communicates with the fuel gas inlet communication hole 40a of the fuel cell stack 14a. One end of a series supply path 60a is connected to the oxidant gas outlet communication hole 42b of the fuel cell stack 14a, and the other end of the series supply path 60a is connected to the fuel gas inlet communication hole 40a of the fuel cell stack 14b. Is done. Similarly, one end of a series supply path 60b is connected to the oxidant gas outlet communication hole 42b of the fuel cell stack 14b, and the other end of the series supply path 60b is connected to a fuel gas inlet communication hole of the fuel cell stack 14c. 40a. A discharge pipe 62 is connected to the oxidant gas outlet communication hole 42b of the fuel cell stack 14c.

  An operation method by the aging device 12 configured as described above will be described below.

  First, as shown in FIG. 1, the fuel cell stacks 14 a to 14 c are arranged in the stack arrangement unit 16. The fuel cell stacks 14 a to 14 c are electrically connected in series to the power supply unit 18 and are connected in series to the hydrogen supply unit 20.

  Next, a positive potential is applied to the anode terminal 46a (anode side electrode 26) of the fuel cell stacks 14a to 14c via the power supply unit 18, and a negative potential is applied to the cathode terminal 46b (cathode side electrode 28). Applied.

  In this state, in the hydrogen supply unit 20, hydrogen gas is supplied to the anode supply pipe 58, and this hydrogen gas is humidified by the humidifier 56 and then into the fuel gas inlet communication hole 40 a of the upstream fuel cell stack 14 a. Supplied. Hydrogen gas is supplied to the fuel gas flow path 36 of each fuel cell 10.

Here, in the fuel cell 10, a positive electrode potential is applied to the anode side via the DC power supply 48, and a negative electrode potential is applied to the cathode side. For this reason, as shown in FIG. 4, the reaction of H ₂ → 2H ⁺ + 2e ⁻ occurs in the anode side electrode 26, and hydrogen ions (H ⁺ ) permeate the solid polymer electrolyte membrane 24 and pass through the cathode side electrode 28. Move to. The cathode side electrode 28 causes a reaction of 2H ⁺ + 2e ⁻ → H ₂ .

  Accordingly, protons (hydrogen ions) move from the anode side electrode 26 to the cathode side electrode 28, and entrained water is supplied to the solid polymer electrolyte membrane 24, so that the water content of the solid polymer electrolyte membrane 24 increases. . Thereby, the aging process by the hydrogen pump operation is performed in the fuel cell stack 14a.

  Hydrogen gas in the oxidant gas flow path 38 of the fuel cell 10 is discharged from the oxidant gas flow path 38 to the oxidant gas outlet communication hole 42b. Therefore, the fuel gas inlet communication hole 40a of the fuel cell stack 14b disposed downstream of the fuel cell stack 14a is connected to the oxidant gas outlet communication hole 42b of the fuel cell stack 14a from the series supply path 60a. Hydrogen gas is supplied.

  Therefore, in the fuel cell stack 14 b, hydrogen gas is supplied to the fuel gas flow path 36 of the fuel cell 10, and hydrogen ions permeate the solid polymer electrolyte membrane 24, whereby hydrogen gas is obtained at the cathode side electrode 28. Thereby, the aging process by the hydrogen pump operation is performed in the fuel cell stack 14b.

  The hydrogen gas discharged from the oxidant gas outlet communication hole 42b of the fuel cell stack 14b is introduced into the fuel gas inlet communication hole 40a of the fuel cell stack 14c. For this reason, in the fuel cell stack 14c, the aging process by the hydrogen pump operation is performed similarly to the fuel cell stacks 14a and 14b.

  In this case, the current density applied by the DC power supply 48 is set to the maximum current density during use. This is because in the hydrogen pump operation, only hydrogen with a small overvoltage is involved in the reaction, so that a large current can be drawn at the early stage of aging. This shortens the aging time.

  Further, since the cathode side electrode 28 side is not affected by the concentration overvoltage due to the diffusion resistance of the reaction gas, it is possible to reduce deterioration due to local reaction concentration on the electrode surface and the distribution of the aging state. Therefore, the electrode surface can be aged uniformly.

  Furthermore, in the case of aging by normal power generation, since a constant current cannot be maintained during aging, the aging is performed by cycling the load current. For this reason, the high potential cycle is repeated, which may induce corrosion of the catalyst alone.

  On the other hand, in aging by hydrogen pump operation, since a large current can be continuously applied at a corrosion potential or lower, it is possible to easily suppress performance deterioration and shorten the aging time. At that time, in the hydrogen pump operation, the hydrogen transferred to the cathode side electrode 28 does not react with the oxidant gas and is discharged to the anode discharge pipe 52 as hydrogen gas. Thereby, there is an effect that hydrogen is not consumed and is extremely economical.

  Further, in the aging by the hydrogen pump operation, the heat generation amount due to the overvoltage loss is reduced, so that the temperature degradation of the solid polymer electrolyte membrane 24 can be effectively suppressed.

  Furthermore, in the hydrogen supply unit 20, the anode supply pipe 58 communicates with the fuel gas inlet communication hole 40a of the fuel cell stack 14a, and the oxidant gas outlet communication hole 42b of the fuel cell stack 14a and the fuel of the fuel cell stack 14b. The gas inlet communication hole 40a is connected by a serial supply path 60a, and the oxidant gas outlet communication hole 42b of the fuel cell stack 14b and the fuel gas inlet communication hole 40a of the fuel cell stack 14c are connected by a serial supply path 60b. Has been.

  Accordingly, the hydrogen discharged from the cathode side of the upstream fuel cell stack 14a is supplied to the anode side of the downstream fuel cell stack 14b, and the hydrogen discharged from the cathode side of the fuel cell stack 14b further flows downstream. Is supplied to the anode side of the side fuel cell stack 14c. Thereby, since hydrogen is used efficiently, the amount of hydrogen supplied from the outside is favorably reduced, and an effect of being economical can be obtained.

  In the power supply unit 18, the positive pole of the DC power supply 48 is electrically connected to the anode terminal 46a of the most upstream fuel cell stack 14a, and the minus pole of the DC power supply 48 is connected to the most downstream fuel cell stack. It is electrically connected to the cathode terminal 46b of 14c.

  Further, the cathode terminal 46b of the fuel cell stack 14a and the anode terminal 46a of the fuel cell stack 14b are electrically connected by a connection cable 52a, and the cathode terminal 46b of the fuel cell stack 14b and the anode terminal 46a of the fuel cell stack 14c. Are electrically connected by a connection cable 52b.

  For this reason, the fuel cell stacks 14 a to 14 c are electrically connected in series to the DC power supply 48. Accordingly, there is an advantage that aging processing by the hydrogen pump operation of a plurality of, for example, three fuel cell stacks 14a to 14c can be performed simultaneously by a single DC power supply 48.

  FIG. 5 is a schematic configuration diagram of an aging device 80 according to the second embodiment of the present invention. The same components as those of the aging device 12 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Similarly, in the third embodiment described below, detailed description thereof is omitted.

  The aging device 80 includes a hydrogen supply unit 82, and a hydrogen storage tank 84 is disposed upstream of the anode supply pipe 58 that constitutes the hydrogen supply unit 82. The hydrogen storage tank 84 includes a hydrogen introduction pipe 86 communicating with a hydrogen supply source (not shown), a distribution pipe 88 for distributing hydrogen gas to other aging devices, and an oxidant of the most downstream fuel cell stack 14c. A circulation path 90 is provided for returning the hydrogen gas discharged from the gas outlet communication hole 42 b to the hydrogen storage tank 84.

  In the second embodiment configured as described above, the hydrogen gas discharged from the most downstream fuel cell stack 14 c is once returned to the hydrogen storage tank 84 via the circulation path 90 and then to the anode supply pipe 58. It can be sent and reused. As a result, the amount of hydrogen used can be further reduced, and an aging process can be performed by a hydrogen pump operation with a smaller amount of hydrogen.

  In that case, the fuel cell stacks 14a to 14c can be configured in units of a small number of blocks obtained by dividing the mounted fuel cell stack (full stack) into three. For this reason, it becomes possible to perform the aging process of the fuel cell stacks 14a to 14c before full stack lamination by the badge process.

  FIG. 6 is a schematic configuration diagram of an aging device 100 according to the third embodiment of the present invention.

  The hydrogen supply unit 102 constituting the aging device 100 has a circulation path 104 having one end connected to the oxidant gas outlet communication hole 42b of the most downstream fuel cell stack 14c and the other end connected to the anode supply pipe 58. Prepare. A hydrogen circulation pump 106 is disposed in the circulation path 104.

  In the third embodiment configured as described above, the hydrogen gas discharged from the oxidant gas outlet communication hole 42b of the most downstream fuel cell stack 14c is supplied to the anode from the circulation path 104 under the driving action of the pump 106. It is returned to the pipe 58 and reused.

  As a result, the amount of hydrogen gas used can be effectively reduced, and effects similar to those of the first and second embodiments can be obtained, such as performing an aging process by economical hydrogen pump operation.

  In the first to third embodiments, the positive electrode potential is applied to the anode side, the negative electrode potential is applied to the cathode side, and the oxidant gas is not supplied to the cathode side. Hydrogen pump operation is performed by supplying humidified hydrogen to the anode side. On the other hand, a positive electrode potential was applied to the cathode side, a negative electrode potential was applied to the anode side, and the cathode side was humidified without supplying an oxidant gas to the anode side. Hydrogen pump operation can also be performed by supplying hydrogen.

It is a schematic block diagram of the aging apparatus for performing the aging process by the hydrogen pump operation to which the operating method of the polymer electrolyte fuel cell which concerns on the 1st Embodiment of this invention is applied. 2 is a cross-sectional explanatory view of the fuel cell. FIG. It is a perspective view explaining the inside of the said fuel cell. It is explanatory drawing of the aging by a hydrogen pump driving | operation. It is a schematic block diagram of the aging apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic block diagram of the aging apparatus based on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12, 80, 100 ... Aging apparatus 14a-14c ... Fuel cell stack 16 ... Stack arrangement | positioning part 18 ... Power supply part 20, 82, 102 ... Hydrogen supply part 24 ... Solid polymer electrolyte membrane 26 ... Anode side electrode 28 ... cathode side electrode 30 ... electrolyte membrane / electrode structure 36 ... fuel gas flow path 38 ... oxidant gas flow path 40a ... fuel gas inlet communication hole 40b ... fuel gas outlet communication hole 42a ... oxidant gas inlet communication hole 42b ... oxidation Agent gas outlet communication hole 46a ... anode terminal 46b ... cathode terminal 48 ... DC power supply 50a, 50b ... cable 52a, 52b ... connection cable 54 ... controller 56 ... humidifier 58 ... anode supply pipe 60a, 60b ... series supply path 62 ... discharge Pipe 84 ... Hydrogen storage tank 86 ... Hydrogen introduction pipe 88 ... Distribution pipe 90, 104 ... Circulation 106 ... Water Circulation pump

Claims (14)

An aging device for aging a polymer electrolyte fuel cell having an electrolyte membrane / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte membrane,
A stack arrangement part in which a plurality of fuel cell stacks having one or more polymer electrolyte fuel cells are arranged;
A power supply for applying a potential to the fuel cell stack;
In a state in which the one electrode side does not perform the supply of the oxidizing gas, when the power supply unit is driven, and the hydrogen supply unit for performing hydrogen pump operation to supply hydrogen humidified to the electrode side of the other lateral ,
With
The hydrogen supply unit is configured to supply the hydrogen to the downstream side after the hydrogen supplied to the other electrode side of the fuel cell stack on the upstream side passes through the electrolyte membrane and is transferred to the one electrode side. An aging device for a polymer electrolyte fuel cell, characterized in that a serial supply path for supplying the other electrode side of the fuel cell stack is provided.   2. The aging device according to claim 1, wherein the hydrogen supply unit discharges the hydrogen discharged from the one electrode side of the most downstream fuel cell stack to the other electrode side of the most upstream fuel cell stack. An aging device for a polymer electrolyte fuel cell, comprising a circulation path for returning.   The aging apparatus according to claim 2, wherein a hydrogen storage tank for storing the hydrogen is disposed in the circulation path.   4. The aging device according to claim 1, wherein the hydrogen supply unit includes a humidifier that is disposed upstream of the most upstream fuel cell stack and humidifies the hydrogen. 5. A solid polymer fuel cell aging device.   5. The aging device according to claim 1, wherein the power supply unit electrically connects the upstream fuel cell stack and the downstream fuel cell stack in series. A solid polymer fuel cell aging device.   6. The aging apparatus according to claim 1, wherein the electrolyte membrane is a hydrocarbon-based electrolyte membrane.   7. The aging device according to claim 1, wherein the power supply unit applies a negative potential to the cathode that is the one electrode, and positively applies to the anode that is the other electrode. An aging device for a polymer electrolyte fuel cell, wherein an electrode potential is applied. An operating method for aging a polymer electrolyte fuel cell having an electrolyte membrane / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte membrane,
Providing a fuel cell stack having one or more polymer electrolyte fuel cells, and arranging a plurality of the fuel cell stacks;
An aging step of performing a hydrogen pump operation for supplying humidified hydrogen to the other electrode side without supplying an oxidant gas to the one electrode side with a potential applied to the fuel cell stack;
Have
In the aging step, the hydrogen supplied to the other electrode side of the fuel cell stack on the upstream side passes through the electrolyte membrane and is transferred to the one electrode side, and then the hydrogen is supplied to the downstream side. A method for operating a polymer electrolyte fuel cell, wherein the fuel cell stack is supplied to the other electrode side.   9. The operation method according to claim 8, wherein the hydrogen discharged from the one electrode side of the most downstream fuel cell stack is returned to the other electrode side of the most upstream fuel cell stack through a circulation path. A method for operating a polymer electrolyte fuel cell, comprising:   10. The operation method according to claim 9, wherein a storage tank for storing the hydrogen is disposed in the circulation path.   11. The operation method according to claim 8, wherein the hydrogen is humidified by a humidifier and then supplied to the most upstream fuel cell stack. 11. Battery operation method.   The operation method according to any one of claims 8 to 11, wherein the upstream fuel cell stack and the downstream fuel cell stack are electrically connected in series. How to operate a fuel cell.   The operation method according to any one of claims 8 to 12, wherein the electrolyte membrane is composed of a hydrocarbon-based electrolyte membrane.   14. The operation method according to claim 8, wherein a negative electrode potential is applied to the cathode, which is the one electrode, and a positive electrode potential is applied to the anode, which is the other electrode. A method for operating a polymer electrolyte fuel cell, comprising:

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