Fuel cell activation device

Abstract

To achieve a higher activation effect than a conventional non-power generation method at lower cost than a conventional power generation method.SOLUTION: A fuel cell activation device activates a fuel cell. The fuel cell includes, from one side to the other, an anode layer, an electrolyte membrane, and a cathode layer. The anode layer and the cathode layer contain platinum as a catalyst. The fuel cell activation device includes an anode-side gas supply device, a cathode-side gas supply device, and a potential scanning circuit. The fuel cell activation device activates the fuel cell by supplying fuel gas to the anode layer via the anode-side gas supply device and low-oxygen gas to the cathode layer via the cathode-side gas supply device, and by controlling the cathode potential via the potential scanning circuit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an apparatus for activating a fuel cell. [Background technology]

[0002] Some fuel cells include, in order from one side, an anode layer, an electrolyte membrane, and a cathode layer. The anode layer and cathode layer contain platinum as a catalyst. During power generation, a fuel gas containing hydrogen is humidified and supplied to the anode layer. On the other hand, an oxidizing gas containing oxygen is humidified and supplied to the cathode layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-161181 Summary of the Invention [Problem to be solved by the invention]

[0004] Such fuel cells often have insufficient performance immediately after production. This can be due to insufficient wetting of the ionomer in the anode catalyst layer, electrolyte membrane, or cathode catalyst layer, or the presence of deposits on the platinum. For these reasons, each fuel cell must be activated before shipping the fuel cell stack. There are two activation methods: power generation and non-power generation, as shown below.

[0005] In this power generation method, fuel gas is actually humidified and supplied to the anode layer, and oxidizing gas is also actually humidified and supplied to the cathode layer. The anode and cathode layers are electrically connected via a load, and electricity is actually generated. The ion flow and generated water accompanying this power generation wash away deposits adhering to the platinum, activating the fuel cell. Furthermore, moisture in the fuel gas and oxidizing gas is supplied to the anode layer, electrolyte membrane, and cathode layer, wetting the fuel cell, thereby activating the fuel cell. However, this power generation method requires high output because it actually generates electricity. This results in high costs for the fuel cell activation device itself and its operation.

[0006] On the other hand, in the non-power generation method, fuel gas is actually humidified and supplied to the anode layer, while oxygen-free inert gas is humidified and supplied to the cathode layer, and the potential is controlled using an external device. That is, when fuel gas is supplied to the anode layer and the cathode potential is controlled by a potential scanning circuit, a proton pump occurs, in which hydrogen ions dissociated from hydrogen molecules in the fuel gas pass through the electrolyte membrane and move to the cathode layer. The hydrogen ions that move to the cathode layer by the proton pump combine with electrons that move to the cathode layer through the load circuit to form hydrogen molecules. The proton pump is achieved through this series of steps.

[0007] With this non-power generation method, oxidizing gas is not supplied to the cathode layer, so the output of the fuel cell can be reduced compared to the power generation method. On the other hand, fuel gas is supplied to the anode layer, so proton pumping can be generated. Therefore, with the non-power generation method, while the output of the fuel cell is reduced, water is transferred as hydrogen ions are transferred by the proton pump, moistening the fuel cell. Therefore, the fuel cell can be activated with lower output compared to the power generation method. However, the activation effect of the fuel cell is lower compared to the power generation method.

[0008] The present invention has been made in view of the above circumstances, and has an object to make it possible to realize a higher activation effect than conventional non-power generation methods at a lower cost than conventional power generation methods. [Means for solving the problem]

[0009] The present inventors discovered that the above object can be achieved by supplying a low-oxygen gas to the cathode layer during proton pumping, and thus arrived at the present invention. The present invention is a fuel cell activation device as described below in (1) and (2).

[0010] (1) A fuel cell activation device for activating a fuel cell, which comprises, in order from one side, an anode layer, an electrolyte membrane, and a cathode layer, the anode layer and the cathode layer containing platinum as a catalyst, an anode-side gas supply device configured to be able to supply a fuel gas as a gas containing hydrogen to the anode layer; a cathode-side gas supply device configured to be able to supply a low-oxygen gas, which is a gas having an oxygen concentration lower than that of air, to the cathode layer; a potential scanning circuit configured to be able to control the potential of the fuel cell; the anode-side gas supply device supplies the fuel gas to the anode layer, the cathode-side gas supply device supplies the low-oxygen gas to the cathode layer, and the potential of the cathode layer is controlled by the potential scanning circuit, thereby activating the fuel cell unit. Fuel cell activation device.

[0011] According to this configuration, a proton pump is generated by supplying fuel gas to the anode layer and controlling the potential of the cathode layer with a potential scanning circuit. The hydrogen ions transferred to the cathode layer by the proton pump combine with oxygen in the low-oxygen gas on the platinum catalyst surface, generating water. This water cleans deposits adhering to the platinum in the cathode layer. The generated water also moistens the fuel cell. This allows for a higher activation effect than conventional proton pumps that supply inert gas to the cathode layer.

[0012] Moreover, since a low-oxygen gas is supplied to the cathode layer, the cathode stoichiometric ratio is lower than when air is supplied. The cathode stoichiometric ratio here refers to the optimal ratio of the amount of gas supplied to the anode layer to the amount of gas supplied to the cathode layer. By lowering the cathode stoichiometric ratio in this way, the amount of fuel gas supplied can be reduced, thereby suppressing the output of the fuel cell unit. This allows the fuel cell activation device body to be made smaller, resulting in lower costs than conventional power generation methods.

[0013] As described above, according to this configuration, by supplying a low-oxygen gas to the cathode layer during proton pumping, it is possible to achieve a higher activation effect than conventional non-power generation methods at a lower cost than conventional power generation methods.

[0014] (2) The cathode-side gas supply device supplies the low-oxygen gas to the cathode layer by supplying air and nitrogen to the cathode layer. The fuel cell activation device according to (1) above.

[0015] According to this configuration, low-oxygen gas can be supplied to the cathode layer simply and inexpensively. [Effects of the Invention]

[0016] As described above, the configuration (1) makes it possible to obtain a higher activation effect than conventional non-power generation methods at a lower cost than conventional power generation methods. Furthermore, the configuration (2) that references the configuration (1) provides additional effects. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing a fuel cell activation device according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a state during activation of a fuel cell by a fuel cell activation device. [Figure 3]FIG. 10 is a schematic diagram showing a state during activation of a fuel cell according to a comparative example. [Figure 4] FIG. 2 is a schematic diagram showing a state during power generation by a fuel cell. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments and can be appropriately modified and implemented within the scope of the present invention.

[0019] [First embodiment] 1 is installed for a fuel cell stack 50s, which contains a plurality of fuel cells 50.

[0020] As shown in FIG. 4, each fuel cell 50 includes, in order from one side, an anode layer 20, an electrolyte membrane 30, and a cathode layer 40. The anode layer 20 includes an anode-side gas diffusion layer 22 and an anode-side catalyst layer 25 provided closer to the electrolyte membrane 30 than the anode layer 20. The cathode layer 40 includes a cathode-side gas diffusion layer 42 and a cathode-side catalyst layer 45 provided closer to the electrolyte membrane 30 than the anode layer 22. Both the anode-side gas diffusion layer 22 and the cathode-side gas diffusion layer 42 are mainly composed of porous layers. The anode-side catalyst layer 25 and the cathode-side catalyst layer 45 contain platinum (Pt) as a catalyst.

[0021] During power generation, the anode layer 20 and the cathode layer 40 are electrically connected via a circuit 60c including a power supply target 60. Hereinafter, a gas containing hydrogen will be referred to as "fuel gas Gh," and a gas containing oxygen will be referred to as "oxidizing gas Go." Note that the oxidizing gas Go referred to here is air containing nitrogen and oxygen. During power generation, fuel gas Gh is humidified and supplied to the anode-side gas diffusion layer 22, and oxidizing gas Go is humidified and supplied to the cathode-side gas diffusion layer 42.

[0022] Hydrogen molecules H2 in the fuel gas Gh in the anode-side gas diffusion layer 22 are converted into hydrogen ions H + dissociates and flows into the anode catalyst layer 25, and electrons e dissociate and flow into the circuit 60c. This reaction is catalyzed by platinum Pt. The hydrogen ions H + The protons pass through the electrolyte membrane 30 and move to the cathode catalyst layer 45. Hereinafter, this phenomenon will be referred to as a "proton pump." On the other hand, the electrons e flow from the anode layer 20 side to the cathode layer 40 side in the circuit 60c.

[0023] The hydrogen ions H that have migrated to the cathode catalyst layer 45 + is combined with oxygen atoms O dissociated from oxygen molecules O2 in the oxidizing gas Go in the cathode-side gas diffusion layer 42 and electrons e from the circuit 60c to form water molecules HO. The water molecules HO diffuse into the cathode-side gas diffusion layer 42. Power generation is achieved through this series of steps.

[0024] The fuel cell 50 described above generally has insufficient performance immediately after production. The reasons for this include insufficient wetting of the ionomer in the anode catalyst layer 25, the electrolyte membrane 30, and the cathode catalyst layer 45, and the presence of deposits d on the platinum Pt. For these reasons, each fuel cell 50 needs to be activated before shipping the fuel cell stack 50s shown in FIG. 1 . The device for this activation is the fuel cell activation device 80.

[0025] 1, the fuel cell activation device 80 includes an anode-side gas supply device 82, a cathode-side gas supply device 84, a potential scanning circuit 83, a cooling device 86, a voltmeter 87, and a control device 88. The anode-side gas supply device 82 and the cathode-side gas supply device 84 are each equipped with humidifiers 82w and 84w that generate water vapor. The control device 88 controls the anode-side gas supply device 82, the cathode-side gas supply device 84, the potential scanning circuit 83, and the cooling device 86.

[0026] The voltmeter 87 is configured to be able to measure the output voltage of each fuel cell 50. The output voltage of each fuel cell 50 measured by this voltmeter 87 is input to a control device 88.

[0027] The cooling device 86 circulates a refrigerant between the fuel cell stack 50s and the radiator to cool each fuel cell 50. The control device 88 controls the cooling device 86 to keep the temperature of each fuel cell 50 at a temperature that facilitates activation.

[0028] 2, the electrodes of the anode layer 20 and the electrodes of the cathode layer 40 are electrically connected via a circuit 83c including a potential scanning circuit 83. The potential scanning circuit 83 is configured to be able to control the potential of the fuel cell 50. Specifically, the fuel cell 50 applies an external force that activates each fuel cell 50 by controlling the potential of the cathode layer 40 relative to the anode layer 20.

[0029] The anode-side gas supply device 82 is configured to be able to supply the fuel gas Gh humidified by the humidifier 82w to the anode-side gas diffusion layer 22. The control device 88 controls the flow rate and pressure of the fuel gas Gh supplied to the anode layer 20 by controlling the anode-side gas supply device 82.

[0030] Hereinafter, a gas with an oxygen concentration lower than that of air will be referred to as a "low-oxygen gas Gc." The cathode stoichiometric ratio of this low-oxygen gas Gc is preferably 1.0 or less. The "cathode stoichiometric ratio" here refers to the optimal ratio of the amount of gas supplied to the anode layer 20 to the amount of gas supplied to the cathode layer 40.

[0031] The cathode-side gas supply device 84 is configured to be able to supply low-oxygen gas by supplying air together with nitrogen gas N2 to the cathode-side gas diffusion layer 42. At this time, the cathode-side gas supply device 84 is also configured to be able to humidify the low-oxygen gas Gc by also supplying water vapor generated by a humidifier 84w. In other words, the cathode-side gas supply device 84 is configured to be able to supply the humidified low-oxygen gas Gc to the cathode-side gas diffusion layer 42. The control device 88 controls the flow rate and pressure of the low-oxygen gas Gc supplied to the cathode layer 40 by controlling the cathode-side gas supply device 84.

[0032] The control device 88 controls the anode-side gas supply device 82 shown in Fig. 2 to humidify the fuel gas Gh and supply it to the anode-side gas diffusion layer 22, and the cathode-side gas supply device 84 to humidify the low-oxygen gas Gc and supply it to the cathode-side gas diffusion layer 42, while controlling the cathode potential with the potential scanning circuit 83. This generates a proton pump.

[0033] 3, the mode in which the cathode-side gas supply device 84 supplies nitrogen gas Gn, rather than low-oxygen gas Gc, to the cathode-side gas diffusion layer 42 during proton pumping is referred to as a comparative mode. In other words, in this comparative mode, the fuel cell 50 is activated by a non-power generation method.

[0034] In this comparative example, hydrogen ions H + dissociates and flows into the anode catalyst layer 25, and electrons e dissociate and flow into the circuit 83c. This reaction is catalyzed by platinum Pt. The hydrogen ions H + passes through the electrolyte membrane 30 and moves to the cathode-side catalyst layer 45. On the other hand, the above-mentioned electrons e flow from the anode layer 20 side to the cathode layer 40 side in the circuit 83c.

[0035] The hydrogen ions H that have migrated to the cathode catalyst layer 45 +The protons combine with electrons e from the circuit 83c to become hydrogen molecules H2. The hydrogen molecules H2 diffuse into the cathode-side gas diffusion layer 42. The flow of ions caused by the above-mentioned proton pump moves water H2O, moistening the fuel cell 50.

[0036] However, unlike the power generation method, hydrogen ions H + Since water molecules HO are not generated from the catalyst, the generated water molecules HO do not wash away the deposits d on the platinum Pt. Furthermore, the generated water molecules HO do not wet the ionomer in the cathode-side diffusion layer 42. Therefore, the activation effect of the fuel cell 50 is lower than in the power generation method.

[0037] In this regard, in the present embodiment shown in FIG. 2, the cathode-side gas supply device 84 supplies low-oxygen gas Gc, rather than nitrogen gas Gn, to the cathode-side gas diffusion layer 42 during proton pumping.

[0038] In the present embodiment, hydrogen ions H are also generated from the hydrogen molecules H2 in the fuel gas Gh in the anode-side gas diffusion layer 22. + dissociates and flows into the anode catalyst layer 25, and electrons e dissociate and flow into the circuit 83c. + passes through the electrolyte membrane 30 and moves to the cathode-side catalyst layer 45. On the other hand, the above-mentioned electrons e flow from the anode layer 20 side to the cathode layer 40 side in the circuit 83c. Up to this point, it is the same as in the case of the above-mentioned comparative embodiment.

[0039] The hydrogen ions H that have migrated to the cathode catalyst layer 45 + is combined with oxygen atoms O dissociated from oxygen molecules O2 in the low-oxygen gas Gc in the cathode-side gas diffusion layer 42 and electrons e from the circuit 60c to form water molecules HO. The water HO washes away deposits d adhering to the platinum Pt. This increases the effective catalytic surface area of the platinum Pt, activating the fuel cell 50.

[0040] Furthermore, in this embodiment, since water molecules H2O are generated in the cathode layer 40, the ionomer in the cathode-side catalyst layer 45 is more easily wetted, and the fuel cell 50 is more easily activated.

[0041] The configuration and effects of this embodiment are summarized below.

[0042] According to this embodiment, as shown in Fig. 2, a proton pump is generated by supplying fuel gas Gh to the anode layer 20 and controlling the potential of the cathode layer 40. The hydrogen ions H + However, when this gas combines with oxygen O2 in the low-oxygen gas Gc, water H2O is generated. This water H2O cleans away any deposits adhering to platinum Pt in the cathode layer 40. In addition, the generated water H2O moistens the fuel cell 50. This makes it possible to achieve a higher activation effect than in a comparative example using a non-power generation method.

[0043] Moreover, since the low-oxygen gas Gc is supplied to the cathode layer 40 at this time, the stoichiometric ratio is lower than when air is supplied. By lowering the stoichiometric ratio in this way, the amount of fuel gas Gh supplied can be reduced, thereby suppressing the output of the fuel cell 50. This allows the fuel cell activation device 80 body to be made smaller, and costs can be reduced compared to when air is supplied to the cathode layer 40, i.e., compared to this power generation method.

[0044] As described above, according to this embodiment, it is possible to achieve a higher activation effect than the non-power generation method at a lower cost than the power generation method.

[0045] Furthermore, the cathode-side gas supply device 84 supplies air and nitrogen N2 to the cathode layer 40, thereby making it possible to supply the low-oxygen gas Gc to the cathode layer 40 simply and inexpensively.

[0046] [Other embodiments] The embodiment described above can be modified, for example, as follows. The potential scanning circuit 83 shown in FIG. 2 may be configured to apply a negative voltage to the cathode layer 40 relative to the anode potential. The control device 88 may then cause the potential scanning circuit 83 to make the potential of the cathode layer 40 negative during proton pumping. In this case, the platinum Pt in the anode layer 20 and the cathode layer 40 is more likely to be negatively charged. This makes it easier for a repulsive force to be generated between the platinum Pt and the deposits d. This is because most of the deposits d that adhere to the platinum Pt are negatively charged. This makes it easier for the deposits d to float from the platinum Pt, making it easier for the deposits d to be washed away from the platinum Pt. [Explanation of symbols]

[0047] 20 anode layer 30 Electrolyte membrane 40 cathode layer 50 fuel cell 80 Fuel cell activation device 82 Anode side gas supply device 83 Potential scanning circuit 84 Cathode side gas supply device Gh Fuel gas Gc hypoxic gas Pt platinum

Claims

1. A fuel cell activation device for activating a fuel cell, which comprises, in order from one side, an anode layer, an electrolyte membrane, and a cathode layer, the anode layer and the cathode layer containing platinum as a catalyst, an anode-side gas supply device configured to be able to supply a fuel gas as a gas containing hydrogen to the anode layer; a cathode-side gas supply device configured to be able to supply a low-oxygen gas, which is a gas having an oxygen concentration lower than that of air, to the cathode layer; a potential scanning circuit configured to be able to control the potential of the fuel cell; the anode-side gas supply device supplies the fuel gas to the anode layer, the cathode-side gas supply device supplies the low-oxygen gas to the cathode layer, and the potential of the cathode layer is controlled by the potential scanning circuit, thereby activating the fuel cell unit. Fuel cell activation device.

2. the cathode-side gas supply device supplies air and nitrogen to the cathode layer, thereby supplying the low-oxygen gas to the cathode layer; The fuel cell activation device according to claim 1 .

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