Fuel battery activation apparatus

Abstract

To efficiently activate a fuel battery cell.SOLUTION: An anode layer 20 and a cathode layer 40 of a fuel battery cell contain platinum as a catalyst. A fuel battery activation apparatus comprises a potential scan circuit 83, anode-side and cathode-side gas supply devices 82 and 84, and a control device. The potential scan circuit 83 is capable of applying a voltage to a fuel battery cell 50. The anode-side gas supply device 82 is capable of supplying a fuel gas as a gas, which contains hydrogen, to the anode layer 20. The cathode-side gas supply device 84 is capable of supplying an inert gas as a gas, which contains nitrogen and does not contain oxygen, to the cathode layer 40. While making a potential of the cathode layer 40 negative by the potential scan circuit 83, the control device supplies the fuel gas to the anode layer 20 by the anode-side gas supply device 82 and supplies the inert gas to the cathode layer 40 by the cathode-side gas supply device 84.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. 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.

[0003] When a load is connected to the fuel cell in this state, hydrogen ions dissociated from hydrogen molecules in the fuel gas pass through the electrolyte membrane and move to the cathode layer, where they combine with oxygen atoms and electrons dissociated from oxygen molecules in the oxidizing gas to form water molecules. This series of steps generates electricity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-161181 Summary of the Invention [Problem to be solved by the invention]

[0005] 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.

[0006] In this power generation method, fuel gas is humidified and supplied to the anode layer, and oxidizing gas is humidified and supplied to the cathode layer, and a load is connected to generate electricity. The electric current during power generation is controlled to repeatedly sweep the potential, and the flow of ions and the water generated by the power generation wash away deposits on the platinum, activating the fuel cell. Furthermore, the moisture in the fuel gas and oxidizing gas, as well as the water generated by power generation, are supplied to the anode layer, electrolyte membrane, and cathode layer, wetting the cell and activating the fuel cell.

[0007] On the other hand, in the non-power generation method, a humidified fuel gas is supplied to the anode layer, while an oxygen-free inert gas such as nitrogen is supplied to the cathode layer, and the potential is controlled using an external device. This non-power generation method, which does not supply oxidizing gas to the cathode layer, can reduce the output of the fuel cell compared to the power generation method. On the other hand, since fuel gas is supplied to the anode layer, moisture is transferred along with the movement of hydrogen ions by the proton pump, moistening the cell. Therefore, the non-power generation method can generate a proton pump to activate the fuel cell while reducing the output of the fuel cell.

[0008] However, while non-power generation methods can reduce equipment costs by suppressing output compared to power generation methods, simply implementing them takes time to activate the fuel cell, and the fuel cell cannot be activated very efficiently.

[0009] The present invention has been made in view of the above circumstances, and has as its object to efficiently activate a fuel cell by a non-electrical generation method. [Means for solving the problem]

[0010] The present inventors have discovered that the fuel cell can be efficiently activated by forcibly lowering the potential of the cathode layer during proton pumping, and have arrived at the present invention.

[0011] The fuel cell activation device of the present invention comprises: A fuel cell is activated, 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.

[0012] The fuel cell activation device includes: a potential scanning circuit configured to be able to apply a voltage to the fuel cell; 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 an inert gas, which is a gas containing nitrogen but not containing oxygen, to the cathode layer; a control device that controls the potential scanning circuit, the anode-side gas supply device, and the cathode-side gas supply device; Equipped with.

[0013] The control device uses the potential scanning circuit to make the potential of the cathode layer negative relative to the anode layer, thereby lowering the potential of the cathode layer compared to when the potential of the cathode layer is not made negative, while supplying the fuel gas to the anode layer using the anode-side gas supply device and supplying the inert gas to the cathode layer using the cathode-side gas supply device. [Effects of the Invention]

[0014] According to the present invention, the potential of the cathode layer is forced to be lower by making the potential of the cathode layer negative relative to the anode layer using a potential scanning circuit, which causes the platinum in the cathode layer to be negatively charged, making it easier for a repulsive force to be generated between the platinum and deposits, and facilitating detachment of deposits from the platinum.

[0015] In this state, a proton pump is generated by supplying fuel gas to the anode layer and inert gas to the cathode layer. The water accompanying the flow of ions caused by the proton pump washes away any floating deposits from the platinum, thereby efficiently activating the fuel cell.

[0016] As described above, according to this configuration, the potential of the cathode layer is made negative relative to the anode layer during proton pumping, thereby enabling efficient activation of the fuel cell. [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] 10 is a graph showing the transition of the potential of the representative portion. [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] The hydrogen molecules H2 in the fuel gas Gh in the anode-side gas diffusion layer 22 flow into the anode-side catalyst layer 25 and are converted into hydrogen ions H + and electrons e. This reaction is catalyzed by platinum Pt. + 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. The device for this activation is a fuel cell activation device 80 shown in FIG. 1.

[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 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.

[0029] Hereinafter, a gas that does not contain oxygen will be referred to as an "inert gas Gn." Specifically, the inert gas Gn in this embodiment is nitrogen N2. The cathode-side gas supply device 84 is configured to be able to supply the inert gas Gn humidified by the humidifier 84w to the cathode-side gas diffusion layer 42. The control device 88 controls the flow rate and pressure of the inert gas Gn supplied to the cathode layer 40 by controlling the cathode-side gas supply device 84.

[0030] The potential scanning circuit 83 is configured to include a potentiostat and the like. The electrode of the anode layer 20 is electrically connected to the electrode of the cathode layer 40 via a circuit 83c that includes the potential scanning circuit 83. The potential scanning circuit 83 is configured to be able to apply a voltage to the anode layer 20 and the cathode layer 40 from outside the fuel cell 50. Specifically, the potential scanning circuit 83 controls the potential of the cathode layer 40 relative to the anode layer 20, for example, by applying a voltage to the cathode layer 40 relative to the anode layer 20.

[0031] Hereinafter, the potential of a predetermined portion of the cathode layer 40 relative to the anode layer 20 will be referred to as the "representative portion potential Vr." The representative portion potential Vr when no voltage is applied will be referred to as the "representative portion natural potential VrN." The representative portion potential Vr when a voltage is applied will be referred to as the "representative portion forced potential VrF."

[0032] In this state, the control device 88 turns on the application of voltage by the potential scanning circuit 83, thereby lowering the potential of the cathode layer 40 compared to when the voltage is not applied. Specifically, when the voltage application is turned on, the representative part potential Vr drops from the representative part natural potential VrN to the representative part forced potential VrF, as shown in Figure 3. The representative part natural potential VrN is, for example, in the range of 0.05 V or more and 0.20 V or less.

[0033] Some of the deposits d that adhere to the platinum Pt are negatively charged. By forcibly making the potential of the cathode layer 40 negative using the potential scanning circuit 83, the platinum Pt of the cathode layer 40 becomes more likely to be negatively charged. This weakens the adsorptive force between the platinum Pt and the deposits d, making it easier for the deposits d to detach from the platinum Pt.

[0034] The control device 88 performs control as follows: The anode-side gas supply device 82 shown in Fig. 2 humidifies the fuel gas Gh and supplies it to the anode-side gas diffusion layer 22, and the cathode-side gas supply device 84 humidifies the inert gas Gn and supplies it to the cathode-side gas diffusion layer 42.

[0035] This generates a proton pump. That is, hydrogen molecules H2 in the fuel gas Gh at the anode side gas diffusion layer 22 are converted into hydrogen ions H + The hydrogen ions H generated in the anode catalyst layer 25 are dissociated into hydrogen ions H and flow into the anode catalyst layer 25, and the electrons e 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.

[0036] The hydrogen ions H that have migrated to the cathode catalyst layer 45 + The protons combine with electrons e from the circuit 83c to form hydrogen molecules H2. The hydrogen molecules H2 diffuse into the cathode-side gas diffusion layer 42. + As the reactants move, water H2O moves and the cells become wet, which reduces the resistance to the movement of reactants and activates the fuel cell 50.

[0037] At this time, the proton pump generates hydrogen ions H + The water HO that moves with the water washes away the deposits d that have been suspended from the platinum Pt due to the negative potential. This not only activates the fuel cell 50 through the cell wetting described above, but also activates the fuel cell 50 due to the increase in the effective catalytic surface area of the platinum Pt.

[0038] The configuration and effects of this embodiment are summarized below.

[0039] Some of the deposits d that adhere to platinum Pt are negatively charged. In this regard, according to this embodiment, the potential of the cathode layer 40 is forcibly lowered by applying a voltage using the potential scanning circuit 83 shown in FIG. 2 so that the potential of the cathode layer 40 is negative relative to the anode layer 20. This makes it easier for the platinum Pt in the cathode layer 40 to be negatively charged. This weakens the adsorptive force between the platinum Pt and the deposits d, making it easier for the deposits d to detach from the platinum Pt.

[0040] In this state, as shown in Figure 2, a proton pump is generated by supplying fuel gas Gh to the anode layer 20 and non-oxidizing gas Gn to the cathode layer. The moisture that moves with the hydrogen ions that accompany the proton pump efficiently washes away the deposits d, whose adsorptive power with platinum Pt has decreased due to the negative potential. This allows the fuel cell 50 to be efficiently activated.

[0041] As described above, according to this embodiment, the potential of the cathode layer 40 is made negative relative to the anode layer 20 during proton pumping, thereby enabling the fuel cell 50 to be activated efficiently.

[0042] Moreover, the inert gas Gn, rather than the oxidizing gas Go, is supplied to the cathode-side gas diffusion layer 42. This allows the output of the fuel cell 50 to be reduced compared to when the oxidizing gas Go is supplied, and therefore does not require expensive equipment. [Explanation of symbols]

[0043] 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 88 Control Device Gh Fuel gas Gn inert gas Pt platinum

Claims

[Claim 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, a potential scanning circuit configured to be able to apply a voltage to the fuel cell; 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 an inert gas, which is a gas containing nitrogen but not containing oxygen, to the cathode layer; a control device that controls the potential scanning circuit, the anode-side gas supply device, and the cathode-side gas supply device; the control device makes the potential of the cathode layer negative with respect to the anode layer using the potential scanning circuit, thereby lowering the potential of the cathode layer compared to a case in which the potential of the cathode layer is not made negative, and supplies the fuel gas to the anode layer using the anode-side gas supply device and supplies the inert gas to the cathode layer using the cathode-side gas supply device. Fuel cell activation device.

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