JP5450120B2 - Aging method for polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to an aging method for a polymer electrolyte fuel cell 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 and a separator.

  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, the fuel cell and the manufacturing method disclosed in Patent Document 1 are characterized by having an aging process in which at least a compressive load is applied to the cell module to advance initial creep. Thereby, the creep of the stack during use of the fuel cell is reduced, and the required fastening load of the fuel cell stack is always maintained within the target life.

JP 2006-294492 A

  In Patent Document 1 described above, initial creep is advanced by applying a compressive load to the cell module for a predetermined time. However, if the initial creep is advanced to a desired state, there is a problem that the predetermined time for applying the compressive load becomes a considerably long time. Thereby, there exists a problem that the aging process of a fuel cell cannot be performed efficiently.

  In addition, when load aging is performed up to a high load region particularly in a high temperature and high humidity environment, an excessive load is applied to the seal portion. For this reason, there exists a possibility that a deformation | transformation and damage may be caused in the separator part and MEA part which contact a seal part.

  The present invention solves this type of problem and provides an aging method for a polymer electrolyte fuel cell capable of performing efficient and good load aging by adjusting the water content of an electrolyte membrane. For the purpose.

  The present invention relates to an aging method for a polymer electrolyte fuel cell 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 the electrolyte membrane and a separator. It is.

  This aging method includes a pressure increasing step for increasing the load of the electrode portion by increasing the moisture content of the electrolyte membrane in a state where a load is applied to the polymer electrolyte fuel cell in the stacking direction, A pressure reducing step for reducing the applied load, and repeatedly performing the pressure increasing step and the pressure reducing step.

  In this aging method, it is preferable to increase the moisture content of the electrolyte membrane by introducing warm water or a humidified gas into at least one electrode side of the electrolyte membrane / electrode structure.

  Furthermore, in this aging method, it is preferable to increase the moisture content of the electrolyte membrane by supplying an oxidant gas and a fuel gas to the polymer electrolyte fuel cell and setting the load current to generate power.

  Furthermore, it is preferable that the pressure reducing step is a step of reducing the moisture content of the electrolyte membrane or a step of removing a load by the pressure receiving member provided at the stacking direction end of the polymer electrolyte fuel cell.

  In the present invention, since the moisture content of the electrolyte membrane is increased and a load is applied to the electrode portion, a load more than necessary is not applied to the seal portion. Accordingly, it is possible to satisfactorily suppress deformation of the separator, damage to the MEA, and the like, and it is possible to reliably perform load aging only on the electrode portion. In addition, the load aging process is efficiently and quickly performed by repeatedly performing the pressure increasing process and the pressure reducing process.

It is a schematic explanatory drawing of the load aging system for enforcing the aging method of the polymer electrolyte fuel cell which concerns on the 1st Embodiment of this invention. It is a principal part disassembled perspective view of the electric power generation cell which comprises the said fuel cell. It is explanatory drawing of the relationship between temperature and humidity, and the swelling amount of a solid polymer electrolyte membrane. FIG. 3 is an explanatory diagram of the relationship between the amount of swelling of the solid polymer electrolyte membrane and the load on the electrode part. It is a relation explanatory drawing of required electrode load and the moisture content swelling amount of the above-mentioned solid polymer electrolyte membrane. It is an image figure of a lifetime electrode load history. It is explanatory drawing at the time of assembling the said fuel cell. It is explanatory drawing of the assembled said fuel cell. It is a schematic explanatory drawing of the load aging system for enforcing the aging method which concerns on the 2nd Embodiment of this invention. It is a schematic explanatory drawing of the load aging system for implementing the aging method which concerns on the 3rd Embodiment of this invention.

  FIG. 1 shows a load aging system 12 for carrying out an aging method for a polymer electrolyte fuel cell 10 according to a first embodiment of the present invention. The load aging system 12 includes a pressurizing device 14, a hot water treatment device 16, and a controller 18.

  As shown in FIGS. 1 and 2, the fuel cell 10 includes a power generation cell 26 in which an electrolyte membrane / electrode structure (MEA) 20 is stacked with first and second separators 22 and 24 interposed therebetween. The plurality of power generation cells 26 are stacked in the direction of arrow A, and a pair of end plates 28 a and 28 b are disposed at both ends of the power generation cell 26 in the stacking direction.

  The 1st and 2nd separators 22 and 24 are comprised by a metal separator (or carbon separator), for example. Between the electrolyte membrane / electrode structure 20 and the first and second separators 22 and 24, a seal member 29 such as a gasket is interposed so as to cover the periphery of the communication hole and the outer periphery of the electrode surface (electrode part) described later. Be dressed. Note that the seal member 29 may be integrally formed with the first and second separators 22 and 24.

  An oxidant gas supply communication hole 30a for supplying an oxidant gas, for example, an oxygen-containing gas, communicates with each other in the arrow A direction, which is the stacking direction, at one end edge of the power generation cell 26 in the arrow B direction. Cooling medium discharge communication holes 32b for discharging the medium and fuel gas discharge communication holes 34b for discharging a fuel gas, for example, a hydrogen-containing gas, are arranged in the direction of arrow C.

  The other end edge of the power generation cell 26 in the direction of the arrow B communicates with each other in the direction of the arrow A, the fuel gas supply communication hole 34a for supplying the fuel gas, and the cooling medium supply communication hole for supplying the cooling medium. 32a and an oxidant gas discharge communication hole 30b for discharging the oxidant gas are arranged in the direction of arrow C.

  The electrolyte membrane / electrode structure 20 includes, for example, a solid polymer electrolyte membrane 36 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side electrode 38 and a cathode side electrode 40 that sandwich the solid polymer electrolyte membrane 36. With.

  The anode side electrode 38 and the cathode side electrode 40 are formed by uniformly coating the surface of the gas diffusion layer with a gas diffusion layer made of carbon paper or the like and porous carbon particles having a platinum alloy supported on the surface. An electrode catalyst layer. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 36.

  The surface 22a of the first separator 22 on the electrolyte membrane / electrode structure 20 side is provided with, for example, an oxidant gas flow path 46 extending in the direction of arrow B. The gas supply communication hole 30a communicates with the oxidant gas discharge communication hole 30b.

  A fuel gas channel 48 communicating with the fuel gas supply communication hole 34a and the fuel gas discharge communication hole 34b is formed on the surface 24a of the second separator 24 on the electrolyte membrane / electrode structure 20 side. Between the surface 24 b of the second separator 24 and the surface 22 b of the first separator 22, a cooling medium flow path 50 that communicates with the cooling medium supply communication hole 32 a and the cooling medium discharge communication hole 32 b is formed.

  As shown in FIG. 1, the pressurizing device 14 includes a plurality of pressing machines (pressure receiving members) 52 disposed on an end plate 28 b that constitutes the upper end portion of the fuel cell 10 stacked in the vertical direction. The pressing machine 52 is provided with a movable part 52a that can be moved back and forth under the action of an actuator (not shown), and the movable part 52a contacts the end plate 28b. For example, a hydraulic cylinder, a pneumatic cylinder, or an electric motor is used as the actuator.

  A holding plate 54 is disposed on the pressing machine 52. The holding plate 54 and the end plate 28 a disposed below are fixed by a plurality of mounting bars 56. In the fuel cell 10, a predetermined tightening load is applied between the holding plate 54 and the end plate 28 a under the biasing action of the pressing device 52.

  The hot water treatment device 16 circulates hot water to at least one electrode side of the electrolyte membrane / electrode structure 20 and, in the first embodiment, to both the anode side electrode 38 side and the cathode side electrode 40 side which are both electrode sides. A hot water circulation system 60 is provided. The hot water circulation system 60 includes a tank 64 in which pure water 62 heated to a predetermined temperature is stored. In this tank 64, a conductivity meter 66 is disposed so as to be immersed in the pure water 62. .

  One end of the hot water supply pipe 68 and one end of the hot water discharge pipe 70 are disposed in the tank 64. A pump 72 is disposed in the hot water supply pipe 68, and the other end side of the hot water supply pipe 68 branches into a first supply pipe 68a and a second supply pipe 68b. The first supply pipe 68 a is connected to the oxidant gas supply communication hole 30 a of the fuel cell 10, while the second supply pipe 68 b is connected to the fuel gas supply communication hole 34 a of the fuel cell 10.

  The other end side of the hot water discharge pipe 70 branches into a first discharge pipe 70a and a second discharge pipe 70b. The first discharge pipe 70 a is connected to the oxidant gas discharge communication hole 30 b of the fuel cell 10, while the second discharge pipe 70 b is connected to the fuel gas discharge communication hole 34 b of the fuel cell 10.

  The aging method of the fuel cell 10 will be described below using the load aging system 12 configured as described above.

  In general, the solid polymer electrolyte membrane 36 swells by absorbing water and has a swelling force that increases the load in the stacking direction. The swelling amount (dimensional change rate) of the solid polymer electrolyte membrane 36 varies depending on temperature and humidity. This relationship is shown in FIG. 3. As the water content (humidity) in the solid polymer electrolyte membrane 36 increases as the temperature increases, the amount of swelling of the solid polymer electrolyte membrane 36 increases. To increase.

  As shown in FIG. 4, the swelling amount of the solid polymer electrolyte membrane 36 and the load on the electrode portion of the electrolyte membrane / electrode structure 20 have a proportional relationship. Thus, the required electrode load depending on the water content (temperature and humidity) in the solid polymer electrolyte membrane 36 is set.

  Therefore, the aging method will be described. In the fuel cell 10, a plurality of power generation cells 26 are stacked on the end plate 28a, and the end plate 28b is disposed at the stack end. Further, a plurality of pressing machines 52 are placed on the end plate 28a, and a holding plate 54 is arranged on the pressing machine 52. The end plate 28 a and the holding plate 54 are fixed by a plurality of mounting bars 56. On the other hand, as shown in FIG. 1, a hot water treatment device 16 is connected to the fuel cell 10.

  Next, the pressing device 52 is energized, and the movable portion 52a presses the end plate 28b in the stacking direction, whereby a predetermined tightening load is applied between the end plates 28a and 28b. In this state, in the hot water treatment device 16, the pump 72 constituting the hot water circulation system 60 is driven.

  Therefore, the pure water (hot water) 62 stored in the tank 64 branches from the hot water supply pipe 68 to the first and second supply pipes 68a and 68b, and the oxidant gas supply communication hole 30a of the fuel cell 10 and the fuel. It is introduced into the gas supply communication hole 34a. As a result, the pure water 62 flows through the oxidant gas passages 46 and the fuel gas passages 48 in the fuel cell 10, and then passes through the oxidant gas discharge communication holes 30 b and the fuel gas discharge communication holes 34 b. And it is discharged | emitted by 2nd discharge piping 70a, 70b.

  Accordingly, the pure water 62 is returned to the tank 64 via the hot water discharge pipe 70, and the pure water 62 heated to a predetermined temperature is circulated and supplied. Note that the temperature of the pure water 62 is set, for example, within a range of 30 ° C. to 55 ° C.

  As described above, since the pure water 62 is circulated through the oxidant gas channel 46 and the fuel gas channel 48, the pure water 62 is added to the solid polymer electrolyte membrane 36 in each electrolyte membrane / electrode structure 20. When introduced, the solid polymer electrolyte membrane 36 swells. At this time, by controlling the temperature of the pure water 62, a necessary electrode load can be obtained as shown in FIG. 5, and a load due to swelling of the solid polymer electrolyte membrane 36 is applied to the electrode portion. .

  It should be noted that the load range applied to the fuel cell 10 is set to a load range (lifetime electrode load range) that may occur throughout the vehicle-mounted environment (see FIG. 6). In this way, by providing the maximum load history in the initial stage, when used in a load range below that, it is possible to suppress a decrease in load and prevent an increase in contact resistance and suppress a decrease in performance. There is.

  At the time of load aging of this embodiment, by increasing the water content of the solid polymer electrolyte membrane 36, there are a pressure increasing step for applying a load to the electrode portion and a pressure reducing step for reducing the load applied to the electrode portion. Repeatedly. In this decompression step, the pressing machine 52 is deenergized and the pressing force applied to the end plate 28b by the movable portion 52a is released. Instead of the decompression process by the pressing machine 52, a step of reducing the moisture content of the solid polymer electrolyte membrane 36 by purging the gas flow path with dry air may be performed.

  The pressure increasing step and the pressure reducing step are performed until it is detected that the fluctuation range of the thickness of the solid polymer electrolyte membrane 36 is within a predetermined value. May be set. Moreover, as shown in FIG. 6, the high load side is a high temperature and high humidity environment, while the low load side is a load range corresponding to a case where the fuel cell 10 is placed in a low temperature environment below freezing and a startup environment. It is said.

  In this case, in the first embodiment, at the time of load aging, the moisture content of the solid polymer electrolyte membrane 36 is increased under the action of the hot water treatment device 16, and the swelling force of the solid polymer electrolyte membrane 36 causes only the electrode portion to A load is applied.

  For this reason, for example, without applying an unnecessary load to the seal member 29, the first and second separators 22 and 24 contacting the seal member 29 are deformed, the electrolyte membrane / electrode structure 20 is damaged, and the like. Can be suppressed satisfactorily. Therefore, in the fuel cell 10, it is possible to satisfactorily perform load aging only on each electrode part. In addition, by repeatedly performing the pressure increasing step and the pressure reducing step, the effect that the load aging process is performed efficiently and quickly can be obtained.

  In the first embodiment, the hot water treatment device 16 is used to increase the water content of the solid polymer electrolyte membrane 36, but the invention is not limited to this. For example, instead of the hot water treatment device 16, a humidified gas supply device (not shown) can be used.

  In this humidified gas supply device, the humidified gas adjusted to a predetermined humidity is supplied to the oxidant gas flow path 46 and the fuel gas flow path 48, and the temperature of the humidified gas is adjusted to thereby obtain a solid polymer electrolyte membrane. It is possible to adjust the amount of swelling of 36 (see FIGS. 3 to 5). Thereby, even if it uses humidified gas instead of the pure water 62, the effect similar to the above is acquired.

  When the load aging process of the fuel cell 10 by the load aging system 12 is completed, the fuel cell 10 is removed from the hot water treatment device 16. Then, as shown in FIG. 7, the attachment bar 56 and the regular attachment bar 74 are sequentially replaced while the end plate 28 b is pressurized by the pressing machine 52. Both ends of the regular mounting bar 74 are fixed to the end plates 28a and 28b.

  Further, as shown in FIG. 8, all the mounting bars 56 are removed, while all the mounting bars 74 are fixed between the end plates 28 a and 28 b, and the pressing machine 52 and the holding plate 54 are disengaged. A battery stack is obtained.

  FIG. 9 is a schematic explanatory diagram of a load aging system 80 for carrying out the aging method according to the second embodiment of the present invention. In addition, the same referential mark is attached | subjected to the component same as the load aging system 12 which concerns on 1st Embodiment, and the detailed description is abbreviate | omitted.

  The load aging system 80 includes a pressurizing device 14 and a power generation aging device 82. The power generation aging device 82 may be configured as a dedicated machine used for power generation aging, or may be configured to perform power generation aging by a fuel cell system incorporating the fuel cell 10 for in-vehicle use. .

  The power generation aging device 82 includes a fuel gas supply system 84 for supplying fuel gas to the fuel cell 10, an oxidant gas supply system 86 for supplying oxidant gas to the fuel cell 10, and the fuel cell 10. And an electronic load 88 to be connected.

  The fuel gas supply system 84 includes a hydrogen tank 90, and hydrogen gas is supplied from the hydrogen tank 90 to the fuel gas supply communication hole 34 a via the hydrogen supply pipe 92, and a variable valve is provided in the hydrogen supply pipe 92. 94a is disposed.

  The fuel gas supply system 84 has a hydrogen discharge pipe 96 communicating with the fuel gas discharge communication hole 34 b, and a bypass line 98 is connected to the hydrogen discharge pipe 96 and the hydrogen supply pipe 92. On-off valves 100 a and 100 b are disposed in the hydrogen discharge pipe 96 and the bypass line 98.

  The oxidant gas supply system 86 includes an air pump (air compressor) 102, and an air supply pipe 104 connected to the air pump 102 is connected to the oxidant gas supply communication hole 30a. The air supply pipe 104 is provided with a variable valve 94b.

  The oxidant gas supply system 86 includes an air discharge pipe 106 connected to the oxidant gas discharge communication hole 30 b, and a bypass line 108 is connected to the air discharge pipe 106 and the air supply pipe 104. The air exhaust pipe 106 and the bypass line 108 are provided with on-off valves 100c and 100d.

  The electronic load 88 has a variable resistance function, and a resistance value can be set so that the output current of the fuel cell 10 is from zero to a maximum current density at the time of use. The maximum current density is a current density that does not cause deterioration in the solid polymer electrolyte membrane 36 due to heat generation, and the set output current is 200% of the maximum current density, preferably 150% or less, more preferably 125% or less. Furthermore, if the current density becomes extremely large, the in-plane power generation distribution becomes large, which is not preferable.

  An aging method by the load aging system 80 configured as described above will be described below.

  In the fuel cell 10, the power generation aging device 82 is driven in a state where a predetermined load is applied by the pressurizing device 14. In the fuel gas supply system 84 constituting the power generation aging device 82, the hydrogen supply pipe 92 is connected to the fuel gas supply communication hole 34a, and the hydrogen discharge pipe 96 is connected to the fuel gas discharge communication hole 34b. In the oxidant gas supply system 86, the air supply pipe 104 is connected to the oxidant gas supply communication hole 30a, and the air discharge pipe 106 is connected to the oxidant gas discharge communication hole 30b. An electronic load 88 is electrically connected to the fuel cell 10.

  The hydrogen tank 90 constituting the fuel gas supply system 84 supplies the fuel gas to the fuel gas supply communication hole 34a via the hydrogen supply pipe 92. On the other hand, air is supplied from the air supply pipe 104 to the oxidant gas supply communication hole 30 a via the air pump 102 constituting the oxidant gas supply system 86. The supplied fuel gas and the supplied oxidant gas are preferably humidified in advance.

  For this reason, hydrogen gas is supplied to the fuel gas channel 48 and air is supplied to the oxidant gas channel 46, and an electrochemical reaction is generated by the electrolyte membrane / electrode structure 20. Accordingly, water is generated by the electrochemical reaction, and this water is supplied to the solid polymer electrolyte membrane 36. As a result, the solid polymer electrolyte membrane 36 swells to increase the moisture content, and can apply a load only to the electrode portion, and the same effect as in the first embodiment can be obtained.

  FIG. 10 is a schematic explanatory diagram of a load aging system 110 for performing the aging method according to the third embodiment of the present invention.

  The load aging system 110 includes a laminator 112 and a hot water treatment device 16 (or a power generation aging device 82). The laminating machine 112 is an assembly machine for assembling the fuel cell 10, and has an inclined pedestal 114 whose upper surface is inclined with respect to the horizontal direction, and a support plate 116 is provided at the lower end position side of the inclined pedestal 114. Provided.

  An end plate 28a is disposed on the support plate 116 side, and a plurality of power generation cells 26 are stacked on the end plate 28a along the inclination of the inclined pedestal 114, and an end plate is provided at the upper end in the stacking direction. 28b is arranged. A pressure plate 118 is disposed on the end plate 28b side, and the pressure plate 118 is pressed toward the support plate 116 via an actuator (not shown).

  In the third embodiment configured as described above, the laminating machine 112 functions as a pressurizing device, and the pressurizing plate 118 is biased toward the end plate 28b, whereby the fuel cell 10 has a predetermined tightening load. Is granted. In this state, the hot water treatment device 16 is driven to increase the water content of the solid polymer electrolyte membrane 36 and perform a pressure increasing step of applying a load to the electrode portion.

  Next, while the operation of the hot water treatment device 16 is stopped, the pressing force to the pressurizing plate 118 is released, and the pressure reducing process by releasing the load of the fuel cell 10 is performed. Then, after the pressure increasing step and the pressure reducing step are repeated a predetermined number of times, the load of the fuel cell 10 is set, and the end plates 28a and 28b are fixed via the mounting bar 74. Then, the fuel cell stack is assembled (see FIG. 8). Therefore, in the third embodiment, the same effect as in the first and second embodiments can be obtained.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12, 80, 110 ... Load aging system 14 ... Pressurization apparatus 16 ... Hot water treatment apparatus 18 ... Controller 20 ... Electrolyte membrane and electrode structure 22, 24 ... Separator 26 ... Power generation cell 28a, 28b ... End plate 30a ... Oxidant gas supply communication hole 30b ... Oxidant gas discharge communication hole 32a ... Cooling medium supply communication hole 32b ... Cooling medium discharge communication hole 34a ... Fuel gas supply communication hole 34b ... Fuel gas discharge communication hole 36 ... Solid polymer electrolyte membrane DESCRIPTION OF SYMBOLS 38 ... Anode side electrode 40 ... Cathode side electrode 46 ... Oxidant gas flow path 48 ... Fuel gas flow path 50 ... Cooling medium flow path 52 ... Press machine 54 ... Holding plate 60 ... Hot water circulation system 62 ... Pure water 64 ... Tank 68 ... Hot water supply piping 68a, 68b ... Supply piping 70 ... Hot water discharge piping 70a, 70b ... Discharge piping 72 ... Pump 82 ... Power generation agent 84 ... Fuel gas supply system 86 ... Oxidant gas supply system 88 ... Electronic load 90 ... Hydrogen tank 92 ... Hydrogen supply pipe 94a, 94b ... Variable valve 96 ... Hydrogen discharge pipes 100a, 100b, 100c, 100d ... On-off valve 102 ... Air pump 104 ... Air supply pipe 106 ... Air discharge pipe 112 ... Laminating machine 114 ... Inclined pedestal 116 ... Support plate 118 ... Pressure plate

Claims (4)

A solid polymer fuel cell aging 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 the electrolyte membrane and a separator,
In a state where a load is applied in the stacking direction to the polymer electrolyte fuel cell, a pressure increasing step for increasing the load of the electrode part by increasing the moisture content of the electrolyte membrane;
A pressure reducing step for reducing a load applied to the electrode part;
And aging the solid polymer fuel cell, wherein the pressure increasing step and the pressure reducing step are repeated.   2. The aging method according to claim 1, wherein the moisture content of the electrolyte membrane is increased by introducing warm water or a humidified gas into at least one electrode side of the electrolyte membrane / electrode structure. Type fuel cell aging method.   2. The aging method according to claim 1, wherein the moisture content of the electrolyte membrane is increased by supplying an oxidant gas and a fuel gas to the polymer electrolyte fuel cell and setting a load current for power generation. A method for aging a polymer electrolyte fuel cell, comprising:   4. The aging method according to claim 1, wherein the depressurization step is a step of reducing a moisture content of the electrolyte membrane, or a pressure receiving pressure provided at an end portion in the stacking direction of the polymer electrolyte fuel cell. A method of aging a polymer electrolyte fuel cell, comprising performing a step of removing a load caused by a member.

Images