JP2010267455A - Aging method and aging device of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to carry out aging of a solid polymer fuel battery cell with a simple device structure. <P>SOLUTION: A testing circuit 400 has a switch element 420 and a resistance element 410 connected in series, and connects mutually a fuel electrode 110 and an air electrode 130 of a fuel battery cell 100 through the switch element 420 and the resistance element 410. A fuel gas supply portion 200 supplies fuel gas to the fuel electrode 110, and an oxidant gas supply portion 300 supplies oxidant gas to the air electrode 130. A control portion 10 controls the switch element 420, and supply of the fuel gas to the fuel electrode 110 and supply of the oxidant gas to the air electrode 130. Then, the control portion 10 performs a first process in which, with the switch element 420 open, the fuel gas is supplied to the fuel electrode 110 and the oxidant gas is supplied to the air electrode 130, and a second process in which the switch element is closed and supply of the oxidant gas to the air electrode 130 is stopped. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solid polymer fuel cell aging method and a fuel cell aging device.

  A solid polymer fuel cell has a configuration in which an electrolyte membrane made of a solid polymer is sandwiched between a fuel electrode having a catalyst layer and an air electrode having a catalyst layer. As the fuel gas supplied to the fuel electrode, pure hydrogen or reformed gas obtained by reforming city gas with a reformer is used. Pure oxygen or air is used as the oxidant gas supplied to the air electrode.

  The polymer electrolyte fuel cell is often lower than the design performance immediately after production, and aging is performed to bring out the initial characteristics of the fuel cell. In addition, when the fuel cell is regenerated after being stopped for a long time, or when the power generation performance such as electromotive force is lowered due to the long-term operation, it is sometimes necessary to perform the same operation as aging.

  Patent Documents 1 and 2 describe that aging is performed by connecting a fuel cell to an aging device, controlling the current value with an external load device, and increasing or decreasing the current value.

JP 2005-251396 A JP 2007-66666 A

  However, when aging is performed by controlling and increasing / decreasing the current value with an external load device, the cost of the external load device increases. Since a certain time is required for aging, the number of fuel cells that can be processed per unit time with one aging device is not large. For this reason, when the cost of the aging device increases, the manufacturing cost of the fuel cell increases.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel cell aging method and fuel cell aging capable of aging solid polymer fuel cells with a simple apparatus configuration. To provide an apparatus.

According to the present invention, the fuel electrode and the air electrode of the fuel cell in which the fuel electrode, the solid polymer electrolyte layer, and the air electrode are stacked are connected to each other through the switch element and the resistance element,
A first step of supplying a fuel gas to the fuel electrode and an oxidant gas to the air electrode while the switch element is open;
A second step of closing the switch element and stopping the supply of the oxidant gas to the air electrode;
There is provided a fuel cell aging method for aging the fuel cell.

According to the present invention, a test circuit that connects a fuel electrode and an air electrode of a polymer electrolyte fuel cell to each other and includes a switch element and a resistance element;
A fuel gas supply unit for supplying fuel gas to the fuel electrode;
An oxidant gas supply unit for supplying an oxidant gas to the air electrode;
A control unit for controlling the switch element, the supply of the fuel gas to the fuel electrode, and the supply of the oxidant gas to the air electrode;
With
The controller is
A first step of supplying the fuel gas to the fuel electrode and supplying the oxidant gas to the air electrode while the switch element is open;
A second step of closing the switch element and stopping the supply of the oxidant gas to the air electrode;
A fuel cell aging device is provided.

  According to the present invention, since it is sufficient that the test circuit has a switch element and a resistance element, aging of the polymer electrolyte fuel cell can be performed with a simple device configuration.

It is a figure showing composition of an aging device concerning an embodiment. It is a flowchart which shows an example of the control which the control part 10 performs. 3 is a chart showing an example of a change over time in the voltage of the fuel cell, the current flowing through the resistance element, and the flow rate of the oxidant gas supplied to the air electrode when the processing shown in FIG. 2 is performed.

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

  FIG. 1 is a diagram illustrating a configuration of an aging device according to the embodiment. The aging apparatus is an apparatus for aging the polymer electrolyte fuel cell 100 and includes a test circuit 400, a fuel gas supply unit 200, an oxidant gas supply unit 300, and a control unit 10. The fuel cell 100 has a configuration in which a fuel electrode 110, a solid polymer electrolyte layer 120, and an air electrode 130 are stacked in this order. A cooling unit 140 is attached to the air electrode 130. The test circuit 400 includes a switch element 420 and a resistance element 410 connected in series, and the fuel electrode 110 and the air electrode 130 of the fuel cell 100 are connected to each other via the switch element 420 and the resistance element 410. To do. The fuel gas supply unit 200 supplies fuel gas to the fuel electrode 110. The oxidant gas supply unit 300 supplies oxidant gas to the air electrode 130. The control unit 10 controls the supply of the fuel gas to the switch element 420, the fuel electrode 110, and the supply of the oxidant gas to the air electrode 130. The control unit 10 supplies the fuel gas to the fuel electrode 110 and supplies the oxidant gas to the air electrode 130 with the switch element 420 open, closes the switch element, and supplies the fuel electrode 110 to the air electrode 130. And a second step of stopping the supply of the oxidant gas.

  In the present embodiment, a valve 310 is provided in a pipe that supplies an oxidant gas from the oxidant gas supply unit 300 to the air electrode 130, and a valve 320 is provided in an exhaust pipe that exhausts exhaust gas from the air electrode 130. Is provided. The control unit 10 controls the supply of the oxidant gas to the air electrode 130 by controlling the opening and closing of the valves 310 and 320. The supply of the fuel gas to the fuel electrode 110 may be controlled by the same method as the supply of the oxidant gas to the air electrode 130.

  The fuel gas supply unit 200 and the oxidant gas supply unit 300 supply the fuel gas and the oxidant gas to the fuel electrode 110 and the air electrode 130 after humidifying, respectively.

  Further, off-gas which is exhaust gas from the fuel electrode 110 is exhausted from the fuel electrode 110 through the exhaust pipe 210. The exhaust pipe 210 is provided with a switching unit 215. The switching unit 215 switches between exhausting offgas as it is or switching back to the fuel gas supply unit 200 and reusing it as fuel gas by switching the exhaust gas exhaust route. Note that the switching unit 215 is also controlled by the control unit 10.

  The test circuit 400 includes a voltmeter 430 and an ammeter 435. The voltmeter 430 measures a potential difference generated between both ends of the resistance element 410, that is, a voltage V between the fuel electrode 110 and the air electrode 130. The ammeter 435 measures the amount of current flowing through the resistance element 410. The measured values of the voltmeter 430 and the ammeter 435 are output to the control unit 10. The control part 10 uses the measured value of the voltmeter 430 and the ammeter 435 for control of each part of an aging apparatus.

  The aging apparatus shown in FIG. 1 has a heating unit (not shown) that heats the fuel cell 100 to a predetermined temperature. Heating by the heating unit is also controlled by the control unit 10.

  FIG. 2 is a flowchart illustrating an example of control performed by the control unit 10. First, the control unit 10 heats and holds the fuel cell 100 at a predetermined temperature (for example, 30 ° C. or more and 80 ° C. or less). Then, the control unit 10 starts the supply of the fuel gas from the fuel gas supply unit 200 to the fuel electrode 110 (Step S10), and opens the switch element 420 to oxidize the oxidant gas supply unit 300 to the air electrode 130. Gas supply is started (step S20). As a result, the fuel cell 100 undergoes an oxidation reaction of the fuel gas to generate power. In addition, since the switch element 420 is open and the fuel cell 100 is in an unloaded state, the voltage between the fuel electrode 110 and the air electrode 130 also increases. While the process of step S <b> 20 is being performed, the control unit 10 controls the switching unit 215 to exhaust off-gas from the fuel electrode 110.

  Then, after a predetermined time (for example, 130 seconds or more and 180 seconds or less) has elapsed, the control unit 10 closes the switch element 420. As a result, the fuel electrode 110 and the air electrode 130 are electrically connected to each other via the resistance element 410, and current starts to flow through the resistance element 410. When the control unit 10 detects that a current has started to flow through the resistance element 410, the control unit 10 stops supplying the oxidant gas to the air electrode 130. Thereby, the power generation in the fuel cell 100 is interrupted (step S30). The measured value of the voltmeter 430, that is, the voltage between the fuel electrode 110 and the air electrode 130 rapidly decreases.

  In this state, the supply of the fuel gas to the fuel electrode 110 is continued. Then, the control unit 10 controls the switching unit 215 to return the off gas from the fuel electrode 110 to the fuel gas supply unit 200, collect the off gas, and reuse it as the fuel gas.

  The control unit 10 stores the measured value V1 of the voltmeter 430 immediately after closing the switch element 420 (for example, after 1 second) (step S40). Then, when the measurement value V2 of step S40 before one cycle is stored, the control unit 10 calculates the difference between the measurement value V1 of step S40 this time and the measurement value V2 of step S40 one cycle before. And when the difference is below a predetermined ratio with respect to V2, for example, below 0.4% (step S50: Yes), an aging process is complete | finished.

  When not ending the aging process (step S50: No), the control unit 10 determines that the voltage between the fuel electrode 110 and the air electrode 130 is a predetermined value, for example, 0.1 V or less (step S60: Yes). Returning to step S20, the above-described steps are repeated. The time required for the processing of step S30 to step S50 is, for example, not less than 20 seconds and not more than 70 seconds.

  3 shows changes over time in the voltage of the fuel cell 100, the current flowing through the resistance element 410, and the flow rate of the oxidant gas (air) supplied to the air electrode 130 when the processing shown in FIG. It is a chart which shows an example. When the switch element 420 is opened and supply of air as an oxidant gas is started, the flow rate of air increases and the voltage of the fuel cell 100 increases. After a while, the air flow rate becomes constant and the voltage of the fuel cell 100 is also stabilized. Thereafter, when the switch element 420 is closed and the supply of air is stopped, a current starts to flow through the resistance element 410. This amount of current increases rapidly and then decreases rapidly. Along with this, the voltage of the fuel cell 100 rapidly decreases. When the voltage of the fuel cell 100 becomes a certain value or less, the switch element 420 is opened again, and the supply of air as the oxidant gas is started.

  Next, the operation and effect of this embodiment will be described. According to the present embodiment, the potential is increased and decreased at the air electrode 130 that is the cathode. For this reason, the surface similar to the pulse cleaning in the cyclic voltammetry method arises on the surface of the air electrode 130, and cleaning is performed. For this reason, aging of a fuel cell can be performed.

  Further, the fuel gas is supplied to the fuel electrode 110 while the supply of the oxidant gas is interrupted. Part of the fuel gas also leaks to the solid polymer electrolyte layer 120 and the air electrode 130 via the fuel electrode 110. The leaked fuel gas reacts with oxygen remaining in the vicinity of the interface between the solid polymer electrolyte layer 120 and the air electrode 130 and the solid polymer electrolyte layer 120 to generate water. The generated water is taken into the solid polymer electrolyte layer 120, thereby reducing the resistance of the fuel cell 100. Also by this action, aging of the polymer electrolyte fuel cell 100 is performed. Also, since the time required for one cycle of processing is short, the time required for aging is short.

  Further, the aging device according to the present embodiment does not need to include an external load device for controlling and increasing / decreasing the current value, and the control unit that controls the opening / closing of the resistance element 410, the switching element 420, and the switching element and the valve. 10 may be provided. Therefore, the polymer electrolyte fuel cell 100 can be aged with a simple apparatus configuration.

  It is also conceivable to realize the same voltage behavior as in the present embodiment using an external load device while continuing the power generation in the fuel cell 100. However, gas shortage may occur in the solid polymer fuel cell 100 due to flooding, which may reduce the output voltage (voltage between the fuel electrode 110 and the air electrode 130). If flooding occurs in the fuel cell 100 at a timing when the voltage between the fuel electrode 110 and the air electrode 130 approaches 0 by an external load device, the voltage between the fuel electrode 110 and the air electrode 130 may be reversed. Come. When the voltage between the fuel electrode 110 and the air electrode 130 is reversed, the fuel cell 100 is deteriorated.

  On the other hand, in this embodiment, since the voltage between the fuel electrode 110 and the air electrode 130 is brought close to 0 by discharging the fuel cell 100 through the resistance element 410, the fuel electrode 110 and the air electrode 130. It is possible to reliably prevent the voltage between the two from being reversed.

  Further, during step S30, off-gas from the fuel electrode 110 is recovered and reused as fuel gas. Therefore, the cost required for aging can be reduced.

  In the example shown in FIG. 1, the fuel cell 100 has a single cell structure, but a stack of a plurality of cells (fuel cell stack) may be used.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

(Example)
A solid polymer fuel cell with an output of 1 kW was prepared and connected to the aging apparatus shown in FIG. This fuel cell has a stack structure in which a plurality of fuel cells 100 are stacked. Then, with the switch element 420 opened, pure hydrogen gas humidified until the dew point reached 82 ° C. was introduced into the fuel electrode 110 at 17 L / min, and the air electrode 130 was humidified until the dew point reached 82 ° C. Air was introduced at 28 L / min. At this time, the central temperature of the stack of fuel cells was controlled at 80 ° C.

  Three minutes after introducing pure hydrogen gas and air, the voltage between the fuel electrode 110 and the air electrode 130 exceeded 0.9V. Thereafter, the switch element 420 was closed, and a 500 mΩ resistance element 410 was connected between the fuel electrode 110 and the air electrode 130. As a result, current began to flow through the resistance element 410. Further, when it was detected that a current started to flow through the resistance element 410, the supply of air to the air electrode 130 was interrupted. As a result, power generation in the fuel cell 100 was interrupted, and the voltage between the fuel electrode 110 and the air electrode 130 rapidly decreased. Then, when the voltage between the fuel electrode 110 and the air electrode 130 became 0.1 V or less, the supply of air to the air electrode 130 was resumed.

  When the above-described cycle was repeated 15 times, the voltage after 1 second from the connection of the resistance element 410 only increased by 0.4% or less with respect to the voltage before 1 cycle. Thereby, the aging process was completed. The time required for aging was 50 minutes.

DESCRIPTION OF SYMBOLS 10 Control part 100 Fuel cell 110 Fuel electrode 120 Solid polymer electrolyte layer 130 Air electrode 140 Cooling part 200 Fuel gas supply part 210 Exhaust pipe 215 Switching part 300 Oxidant gas supply part 310 Valve 320 Valve 400 Test circuit 410 Resistance element 420 Switch element 430 Voltmeter 435 Ammeter

Claims (7)

Connecting the fuel electrode and the air electrode of the fuel cell in which the fuel electrode, the solid polymer electrolyte layer, and the air electrode are stacked, to each other via a switch element and a resistance element
A first step of supplying a fuel gas to the fuel electrode and an oxidant gas to the air electrode while the switch element is open;
A second step of closing the switch element and stopping the supply of the oxidant gas to the air electrode;
A fuel cell aging method for aging the fuel cell. The fuel cell aging method according to claim 1,
A fuel cell aging method in which the fuel gas is continuously supplied to the fuel electrode in the second step. The fuel cell aging method according to claim 2,
A fuel cell aging method in which off-gas from the fuel electrode in the second step is recovered and reused as the fuel gas. In the aging method of the fuel cell as described in any one of Claims 1-3,
A fuel cell aging method in which the first step and the second step are repeated. The fuel cell aging method according to claim 4,
The fuel cell aging method of returning to the first step when the voltage between the fuel electrode and the air electrode becomes 0.1 V or less in the second step. The fuel cell aging method according to claim 4 or 5,
Each of the first steps is performed for a certain period of time,
The difference between the voltage V1 between the fuel electrode and the air electrode at the initial stage of the second process and the voltage V2 between the fuel electrode and the air electrode at the initial stage of the second process one cycle before is A fuel cell aging method in which the repetition of the first step and the second step is terminated when the voltage becomes 0.4% or less with respect to the voltage V2. A test circuit for connecting the fuel electrode and the air electrode of the polymer electrolyte fuel cell to each other via a switch element and a resistance element;
A fuel gas supply unit for supplying fuel gas to the fuel electrode;
An oxidant gas supply unit for supplying an oxidant gas to the air electrode;
A control unit for controlling the switch element, the supply of the fuel gas to the fuel electrode, and the supply of the oxidant gas to the air electrode;
With
The controller is
A first step of supplying the fuel gas to the fuel electrode and supplying the oxidant gas to the air electrode while the switch element is open;
A second step of closing the switch element and stopping the supply of the oxidant gas to the air electrode;
An aging device that makes

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