JP5167007B2 - 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, 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 can efficiently introduce water into the electrolyte membrane and remove impurities in the electrolyte membrane / electrode structure, thereby improving the efficiency of the aging treatment. It is an object of the present invention to provide a aging method for a polymer electrolyte fuel cell.

  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.

The aging process includes a first step of circulating hot water through the at least one electrode side of the membrane electrode assembly is carried out after the first step, a polymer electrolyte fuel cell in the oxidant gas and fuel And a second step of performing power generation aging by supplying a gas and flowing a load current to a load connected to the polymer electrolyte fuel cell .

  In this aging method, it is preferable to perform power generation aging by setting the load current to 30% or more of the maximum current density of the polymer electrolyte fuel cell.

  Furthermore, in this aging method, it is preferable to perform power generation aging by setting the load current to be equal to or higher than the maximum current density of the polymer electrolyte fuel cell.

  Furthermore, in this aging method, pure water circulated to at least one electrode side is heated by circulating a heated cooling medium through a cooling medium flow path provided in the polymer electrolyte fuel cell. It is preferable to have a step of obtaining warm water.

  Further, the aging method distributes the heated cooling medium through the cooling medium flow path provided in the polymer electrolyte fuel cell, and uses the heated cooling medium as hot water as at least one electrode side. It is preferable to have a step of circulating the product.

  Furthermore, in this aging method, it is preferable that the warm water is pure water of 30 ° C to 55 ° C.

  In the present invention, since warm water is circulated to at least one electrode side of the electrolyte membrane / electrode structure, for example, water is efficiently introduced into the electrolyte membrane as compared with the case of using room temperature water or water vapor. be able to. Thereby, each overvoltage of resistance overvoltage, density | concentration overvoltage, and active overvoltage can be reduced effectively. Therefore, high-load operation is possible from the beginning of power generation aging, the aging time is shortened well, and the amount of hydrogen used during aging is reduced, which is economical.

  In addition, impurities such as residual solvents and adhesive components in the electrolyte membrane / electrode structure are removed, and a cleaning function can be provided. Furthermore, when the electrolyte membrane swells, the reaction area on the catalyst surface is effectively expanded.

  FIG. 1 is a schematic explanatory diagram of a hot water treatment apparatus 12 for carrying out an aging method for a polymer electrolyte fuel cell 10 according to a first embodiment of the present invention.

  The fuel cell 10 includes, for example, an electrolyte membrane / electrode structure 20 in which a hydrocarbon-based solid polymer electrolyte membrane 14 is sandwiched between an anode-side electrode 16 and a cathode-side electrode 18, and the electrolyte membrane / electrode structure 20 is The unit cell 23 is configured by being sandwiched between the anode side separator 22a and the cathode side separator 22b.

  A predetermined number of unit cells 23 are stacked in the direction of arrow A, and end plates 25a and 25b are disposed at both ends of the stacking direction via terminal plates and insulating plates (not shown). The end plates 25a and 25b clamp and hold a plurality of unit cells 23 in the stacking direction (arrow A direction) via a tie rod (not shown), or constitute an end plate of a box-shaped casing to stack the unit cells 23. Tighten and hold in the direction.

  The anode side separator 22a and the cathode side separator 22b are made of carbon plates or metal plates, and are provided with a seal member (not shown). The solid polymer electrolyte membrane 14 may be a fluorine-based membrane such as perfluorocarbon, for example.

  A fuel gas flow path 24 is formed between the electrolyte membrane / electrode structure 20 and the anode side separator 22a, and an oxidant is provided between the electrolyte membrane / electrode structure 20 and the cathode side separator 22b. A gas flow path 26 is formed. A cooling medium flow path 28 is formed between the anode side separator 22a and the cathode side separator 22b.

  The fuel cell 10 includes a fuel gas inlet communication hole 30a for supplying a fuel gas such as a hydrogen-containing gas to one end side, and an oxidant gas inlet communication for supplying an oxidant gas such as air (oxygen-containing gas). A hole 32a, a fuel gas outlet communication hole 30b for discharging the fuel gas, and an oxidant gas outlet communication hole 32b for discharging the oxidant gas are formed. At the other end of the fuel cell 10, a cooling medium inlet communication hole 34a for supplying a cooling medium and a cooling medium outlet communication hole 34b for discharging the cooling medium are formed.

  The hot water treatment device 12 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 16 side and the cathode side electrode 18 side, which are both electrode sides. And a cooling medium circulation system 40 for circulating and circulating the cooling medium heated in the cooling medium flow path 28.

  The hot water circulation system 36 includes a tank 44 in which pure water 42 is stored, and a conductivity meter 46 is immersed in the pure water 42 and disposed in the tank 44. One end of the hot water supply pipe 48 and one end of the hot water discharge pipe 50 are arranged in the tank 44. A pump 52 is disposed in the hot water supply pipe 48, and the other end side of the hot water supply pipe 48 branches into a first supply pipe 48a and a second supply pipe 48b. The first supply pipe 48 a is connected to the fuel gas inlet communication hole 30 a of the fuel cell 10, while the second supply pipe 48 b is connected to the oxidant gas inlet communication hole 32 a of the fuel cell 10.

  The other end side of the hot water discharge pipe 50 branches into a first discharge pipe 50a and a second discharge pipe 50b. The first exhaust pipe 50 a is connected to the fuel gas outlet communication hole 30 b of the fuel cell 10, while the second exhaust pipe 50 b is connected to the oxidant gas outlet communication hole 32 b of the fuel cell 10.

  The cooling medium circulation system 40 includes a refrigerant circulation pump 62, and this pump 62 is disposed in the refrigerant circulation pipe 64. Both ends of the refrigerant circulation pipe 64 are connected to the cooling medium inlet communication hole 34 a and the cooling medium outlet communication hole 34 b of the fuel cell 10, and a heater 66 is disposed on the downstream side of the pump 62. The fuel cell 10 is controlled via the controller 68.

  FIG. 2 is a schematic configuration diagram of a power generation aging device 70 for performing a power generation aging process on the fuel cell 10 after the hot water treatment of the fuel cell 10. The power generation aging device 70 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 70 includes a fuel gas supply system 72 for supplying fuel gas to the fuel cell 10, an oxidant gas supply system 74 for supplying oxidant gas to the fuel cell 10, and the fuel cell 10. And an electronic load 76 to be connected.

  The fuel gas supply system 72 includes a hydrogen tank 78, and hydrogen gas is supplied from the hydrogen tank 78 through the hydrogen supply pipe 80 to the fuel gas inlet communication hole 30 a, and a variable valve is provided in the hydrogen supply pipe 80. 82a is disposed.

  The fuel gas supply system 72 has a hydrogen discharge pipe 84 that communicates with the fuel gas outlet communication hole 30 b, and a bypass line 86 is connected to the hydrogen discharge pipe 84 and the hydrogen supply pipe 80. On-off valves 88 a and 88 b are disposed in the hydrogen discharge pipe 84 and the bypass line 86.

  The oxidant gas supply system 74 includes an air pump (air compressor) 90, and an air supply pipe 92 connected to the air pump 90 is connected to the oxidant gas inlet communication hole 32a. The air supply pipe 92 is provided with a variable valve 82b.

  The oxidant gas supply system 74 includes an air discharge pipe 94 connected to the oxidant gas outlet communication hole 32 b, and a bypass line 96 is connected to the air discharge pipe 94 and the air supply pipe 92. The air discharge pipe 94 and the bypass line 96 are provided with on-off valves 88c and 88d.

  The electronic load 76 has a variable resistance function, and the resistance value can be set so that the output current of the fuel cell 10 is zero or more than the maximum current density in use. The maximum current density is a current density that does not cause deterioration in the solid polymer electrolyte membrane 14 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.

  The operation method by the hot water treatment device 12 and the power generation aging device 70 configured as described above will be described below along the flowchart shown in FIG.

  First, in the fuel cell 10, a predetermined number of unit cells 23 are stacked in the direction of arrow A in FIG. 1, and terminal plates, insulating plates and end plates 25a and 25b are provided at both ends in the stacking direction (not shown). Be placed. The end plates 25a and 25b are clamped and held by a tie rod (not shown), or clamped and held in a stacking direction by a box-shaped casing, and the stack is assembled (step S1).

  The stacked fuel cell 10 is attached to the hot water treatment device 12. Specifically, in the hot water circulation system 36, the first supply pipe 48 a branched from the hot water supply pipe 48 is connected to the fuel gas inlet communication hole 30 a of the fuel cell 10, while the first supply pipe 48 a branched from the hot water supply pipe 48. The two supply pipes 48 b are connected to the oxidant gas inlet communication hole 32 a of the fuel cell 10.

  Further, the first discharge pipe 50a branched from the hot water discharge pipe 50 is connected to the fuel gas outlet communication hole 30b of the fuel cell 10, while the second discharge pipe 50b branched from the hot water discharge pipe 50 is connected to the fuel cell. 10 oxidant gas outlet communication holes 32b.

  In the cooling medium circulation system 40, both end portions of the refrigerant circulation pipe 64 are connected to the cooling medium inlet communication hole 34 a and the cooling medium outlet communication hole 34 b of the fuel cell 10.

  Subsequently, it progresses to step S2, the warm water processing apparatus 12 is driven, and warm water aging is started. In this hot water aging, the cooling medium circulates in the refrigerant circulation pipe 64 under the action of the pump 62 constituting the cooling medium circulation system 40, and this cooling medium passes hot water, which will be described later, through a heater 66 to a predetermined temperature. It is heated to the temperature necessary for heating.

  The heated cooling medium is supplied from the cooling medium inlet communication hole 34a into the cooling medium flow path 28 in the fuel cell 10, and then returned to the refrigerant circulation pipe 64 from the cooling medium outlet communication hole 34b. Therefore, in the fuel cell 10, the cooling medium heated to a predetermined temperature circulates in each cooling medium flow path 28.

  On the other hand, pure water (room temperature water in the tank 44) 42 stored in the tank 44 is sent to the hot water supply pipe 48 under the drive action of the pump 52 that constitutes the hot water circulation system 36. The pure water 42 is introduced into the fuel gas inlet communication hole 30a and the oxidant gas inlet communication hole 32a of the fuel cell 10 through the first and second supply pipes 48a and 48b branched from the hot water supply pipe 48.

  Thus, after the pure water 42 is circulated through the fuel gas passages 24 and the oxidant gas passages 26 in the fuel cell 10, the pure water 42 is first supplied from the fuel gas outlet communication hole 30b and the oxidant gas outlet communication hole 32b. And discharged to the second discharge pipes 50a and 50b. Accordingly, since the pure water 42 is returned to the tank 44 through the hot water discharge pipe 50, the pure water 42 in the tank 44 is circulated and supplied in the hot water circulation system 36.

  At that time, the pure water 42 supplied to the fuel gas passage 24 and the oxidant gas passage 26 is heated by the cooling medium circulated and supplied to the cooling medium passage 28. For this reason, the pure water 42 is heated to, for example, 50 ° C., and is supplied to the fuel gas passage 24 and the oxidant gas passage 26 as hot water. Accordingly, since warm water is directly supplied to each electrolyte membrane / electrode structure 20, pure water 42 can be efficiently and rapidly introduced into the solid polymer electrolyte membrane 14.

  In addition, the temperature of warm water is set in the range of 30 degreeC-55 degreeC, for example. When the warm water temperature is less than 30 ° C., the effect of warm water cannot be obtained, water cannot be quickly and efficiently introduced into the solid polymer electrolyte membrane 14, and the washing effect of the warm water cannot be sufficiently obtained. The efficiency of the cleaning operation of the solid polymer electrolyte membrane 14 cannot be achieved. On the other hand, when the hot water temperature exceeds 55 ° C., the tightening load of the fuel cell 10 exceeds the allowable load due to the expansion of the unit cell 23.

  Therefore, when the hot water aging process is performed for a predetermined time, for example, the aging operation is completed (YES in step S3). If the conductivity of the hot water detected by the conductivity meter 46 is equal to or higher than a predetermined value during the hot water aging, the hot water in the tank 44 is replaced.

  After completion of aging, the process proceeds to step S4, where air purge is performed. First, the drive of the pump 52 constituting the hot water circulation system 36 is stopped and the drive of the pump 62 constituting the cooling medium circulation system 40 is stopped. Thereby, the circulation of the hot water and the cooling medium into the fuel cell 10 is stopped.

  Next, air is supplied to the fuel gas passage 24 and the oxidant gas passage 26 sequentially or simultaneously via an air supply system (not shown). As a result, the fuel gas passage 24 and the oxidant gas passage 26 are purged with air. When the air purge process is completed or before the air purge process, the fuel cell 10 is removed from the hot water treatment device 12.

  The fuel cell 10 after the hot water aging process is attached to a power generation aging device 70 as shown in FIG. In the fuel gas supply system 72, the hydrogen supply pipe 80 is connected to the fuel gas inlet communication hole 30a, and the hydrogen discharge pipe 84 is connected to the fuel gas outlet communication hole 30b. In the oxidant gas supply system 74, the air supply pipe 92 is connected to the oxidant gas inlet communication hole 32a, and the air discharge pipe 94 is connected to the oxidant gas outlet communication hole 32b. In addition, an electronic load 76 is electrically connected to the fuel cell 10.

  The hydrogen tank 78 constituting the fuel gas supply system 72 supplies the fuel gas to the fuel gas inlet communication hole 30 a via the hydrogen supply pipe 80. On the other hand, air is supplied from the air supply pipe 92 to the oxidant gas inlet communication hole 32 a via the air pump 90 constituting the oxidant gas supply system 74.

  For this reason, hydrogen gas is supplied to the fuel gas passage 24 and air is supplied to the oxidant gas passage 26, and an electrochemical reaction is generated by the electrolyte membrane / electrode structure 20. Therefore, power generation by the fuel cell 10 is started, and the current output from the fuel cell 10 via the electronic load 76 is increased and controlled stepwise as shown in FIG.

  In the electronic load 76, the output current of the fuel cell 10 is set to 30% or more of the maximum current density during use to the maximum current density or more. Thus, power generation aging is performed. For example, when a predetermined time elapses (YES in step S6), the aging operation of the fuel cell 10 is completed.

  In this case, in the first embodiment, a step of supplying hot water directly to the electrolyte membrane / electrode structure 20 constituting the fuel cell 10 via the hot water treatment device 12 is performed before the power generation aging step. For this reason, for example, compared with the case where normal temperature water, water vapor | steam, etc. are used, water can be introduce | transduced into the solid polymer electrolyte membrane 14 rapidly and efficiently.

  Therefore, each of the resistance overvoltage, concentration overvoltage, and active overvoltage can be effectively reduced, and a large current can be applied in a short time during the power generation aging process. That is, it can be set to 30% or more of the maximum current density, and in some cases, to the above-mentioned maximum current density, the time required for power generation aging can be reduced well, and the amount of hydrogen used during power generation aging can be reduced. The effect that it is the target is acquired.

  Furthermore, impurities such as residual solvent and adhesive component in the electrolyte membrane / electrode structure 20 are removed, and a cleaning function can be obtained. In addition, there is an advantage that the reaction region on the catalyst surface is effectively expanded by swelling the solid polymer electrolyte membrane 14.

  Further, in the fuel cell 10, warm water is supplied to the fuel gas flow path 24 and the oxidant gas flow path 26, while a warmed cooling medium is supplied to the cooling medium flow path 28. The pressure balance in the battery 10 can be maintained well.

  In the first embodiment, hot water aging is performed by supplying hot water to the fuel gas channel 24 and the oxidant gas channel 26, but the present invention is not limited to this. For example, warm water aging may be performed by supplying warm water only to the fuel gas channel 24 or only to the oxidant gas channel 26.

  FIG. 5 is a schematic explanatory diagram of a hot water treatment apparatus 100 for carrying out an aging method for a polymer electrolyte fuel cell according to a second embodiment of the present invention. In addition, the same referential mark is attached | subjected to the component same as the hot water treatment apparatus 12 which concerns on 1st Embodiment, and the detailed description is abbreviate | omitted.

  In the hot water treatment apparatus 100, only a single pump 62 is used as a pump for driving the hot water circulation system 36 and the cooling medium circulation system 40. The first and second supply pipes 48a and 48b and the refrigerant circulation pipe 64 communicate with each other through the hot water supply bypass pipe 102, and the first and second discharge pipes 50a and 50b and the refrigerant circulation pipe 64 are connected to the hot water discharge bypass 64. It communicates via the pipe 104. A tank 44 is disposed in the refrigerant circulation pipe 64.

  In the hot water aging process by the hot water treatment apparatus 100 configured as described above, when the pump 62 is driven, the heated cooling medium is circulated in the cooling medium flow path 28 via the refrigerant circulation pipe 64, and Hot water (cooling medium) is supplied from the hot water supply bypass pipe 102 to the first and second supply pipes 48a and 48b.

  This hot water is supplied to the fuel gas flow path 24 and the oxidant gas flow path 26 and directly supplied to both surfaces of each electrolyte membrane / electrode structure 20, and then the hot water is supplied from the first and second discharge pipes 50a, 50b. It returns to the tank 44 through the discharge bypass pipe 104. For this reason, circulating supply of warm water is performed.

  At that time, in the second embodiment, the hot water and the cooling medium are respectively supplied to the hot water circulation system 36 and the cooling medium circulation system 40 through a single pump 62. Therefore, the effect that simplification of the structure of the whole warm water treatment apparatus 100 is achieved is obtained.

It is a schematic explanatory drawing of the hot water treatment apparatus for implementing the aging method of the polymer electrolyte fuel cell which concerns on the 1st Embodiment of this invention. It is a schematic explanatory drawing of the electric power generation aging apparatus for implementing the said aging method. It is a flowchart explaining the said aging method. It is load current explanatory drawing of a power generation aging process. It is a schematic explanatory drawing of the hot water treatment apparatus for enforcing the aging method of the polymer electrolyte fuel cell which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12, 100 ... Hot water processing apparatus 14 ... Solid polymer electrolyte membrane 16 ... Anode side electrode 18 ... Cathode side electrode 20 ... Electrolyte membrane and electrode structure 23 ... Unit cell 24 ... Fuel gas flow path 26 ... Oxidant Gas channel 28 ... cooling medium channel 30a ... fuel gas inlet communication hole 30b ... fuel gas outlet communication hole 32a ... oxidant gas inlet communication hole 32b ... oxidant gas outlet communication hole 34a ... cooling medium inlet communication hole 34b ... cooling medium Outlet communication hole 36 ... warm water circulation system 40 ... cooling medium circulation system 42 ... pure water 44 ... tank 46 ... conductivity meter 48 ... warm water supply piping 48a, 48b ... supply piping 50 ... warm water discharge piping 50a, 50b ... discharge piping 52, 62 ... Pump 70 ... Power generation aging device 72 ... Fuel gas supply system 74 ... Oxidant gas supply system 76 ... Electronic load 78 ... Hydrogen tank 90 ... Air pump 102 ... Warm Water supply bypass piping 104 ... Warm water discharge bypass piping

Claims (6)

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,
A first step of circulating hot water to at least one electrode side of the electrolyte membrane / electrode structure;
Power generation is performed by supplying an oxidant gas and a fuel gas to the polymer electrolyte fuel cell and flowing a load current to a load connected to the polymer electrolyte fuel cell. A second step of aging;
A method for aging a polymer electrolyte fuel cell, comprising:   The aging method according to claim 1, wherein the power generation aging is performed by setting the load current to 30% or more of the maximum current density of the polymer electrolyte fuel cell. Method.   The aging method according to claim 1 or 2, wherein the power generation aging is performed by setting the load current to be equal to or higher than a maximum current density of the polymer electrolyte fuel cell. .   4. The aging method according to claim 1, wherein at least one of the aging methods is performed by circulating a heated cooling medium through a cooling medium flow path provided in the polymer electrolyte fuel cell. A solid polymer fuel cell aging method comprising a step of heating pure water distributed to the electrode side to obtain the warm water.   The aging method according to any one of claims 1 to 3, wherein the heated cooling medium is circulated through the cooling medium flow path provided in the polymer electrolyte fuel cell, and the heated A solid polymer fuel cell aging method comprising a step of circulating a cooling medium as at least one of the electrodes as the warm water.   6. The aging method according to claim 1, wherein the hot water is pure water at 30 ° C. to 55 ° C. 6.

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