Activation method for solid polymer fuel cell

Abstract

To provide a method capable of activating a solid polymer fuel cell in a shorter time.SOLUTION: Disclosed is an activation method for a solid polymer fuel cell having an electrode membrane structure in which an anode electrode and a cathode electrode are disposed oppositely via a solid polymer membrane. The activation method for the solid polymer fuel cell includes: pressurizing and supplying a humidified hydrogen containing gas, that is humidified, to the anode electrode while heating the solid polymer fuel cell within a predetermined range (preferably within a range from 100°C or higher to 300°C or lower, more preferably within a range from 100°C or higher to 200°C or lower and further preferably within a range from 100°C or higher to 150°C or lower); and pressurizing and supplying a humidified oxygen containing gas or a humidified nitrogen containing inert gas, that is humidified, to the cathode electrode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for activating a polymer electrolyte fuel cell. [Background technology]

[0002] In recent years, research and development into fuel cells, which contribute to energy efficiency, has been conducted to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. A well-known example of a fuel cell is a polymer electrolyte fuel cell (PEFC), which has a membrane electrode assembly (MEA) in which an anode and a cathode are arranged opposite each other with a solid polymer membrane interposed between them. This type of PEFC generally has low power generation performance immediately after manufacture. For this reason, it is common to activate PEFCs by performing an activation process (aging) before shipping. One known activation method for PEFCs involves heating the PEFC or applying a voltage varying within a predetermined range between the cathode and anode while supplying a humidified hydrogen-containing gas to the anode and a humidified oxygen-containing or nitrogen-containing inert gas to the cathode (see, for example, Reference 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 125840 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology relating to polymer electrolyte fuel cells, one of the challenges is to shorten the activation process time in order to improve productivity, and therefore further improvements in conventional activation methods are desired.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a method for activating a polymer electrolyte fuel cell in a shorter time. [Means for solving the problem]

[0006] The present inventors have found that the above-mentioned problems can be solved by supplying a predetermined humidified gas under pressure to the anode and cathode of a polymer electrolyte fuel cell while heating the fuel cell during activation, or by heating the polymer electrolyte fuel cell and then supplying a predetermined humidified gas to the anode and cathode while the heating is stopped, and have completed the present invention.

[0007] (1) A method for activating a polymer electrolyte fuel cell having an electrode membrane structure in which an anode and a cathode are arranged opposite each other via a solid polymer membrane, the method comprising heating the polymer electrolyte fuel cell at a set temperature set within a predetermined range, pressurizing and supplying a humidified hydrogen-containing gas to the anode, and pressurizing and supplying a humidified oxygen-containing gas or a humidified nitrogen-containing inert gas to the cathode.

[0008] According to the method for activating a polymer electrolyte fuel cell (1), a humidified hydrogen-containing gas is supplied to the anode and a humidified oxygen-containing gas or a humidified nitrogen-containing inert gas is supplied to the cathode while the polymer electrolyte fuel cell is heated. This facilitates catalyst activation in the catalyst layers at the anode and cathode. Furthermore, the water vapor contained in the humidified gas facilitates wetting of the catalyst layers and the polymer electrolyte membrane at the anode and cathode. Furthermore, since a pressurized humidified hydrogen-containing gas is supplied to the anode and a pressurized humidified oxygen-containing gas or a humidified nitrogen-containing inert gas is supplied to the cathode, water vapor can be efficiently supplied to the anode and cathode. Therefore, the polymer electrolyte fuel cell can be activated in a shorter time.

[0009] (2) A method for activating a polymer electrolyte fuel cell according to (1), wherein the humidified hydrogen-containing gas is heated to the set temperature, and the humidified oxygen-containing gas or humidified nitrogen-containing inert gas is heated to the set temperature.

[0010] According to the activation method for a polymer electrolyte fuel cell (2), the decrease in humidity due to heating of the humidified hydrogen-containing gas when supplied to the anode and the decrease in humidity due to heating of the humidified oxygen-containing gas when supplied to the cathode are suppressed, so that water vapor can be supplied to the anode and cathode more efficiently.

[0011] (3) The method for activating a polymer electrolyte fuel cell according to (1) or (2), further comprising applying a voltage varying within a predetermined range between the cathode and the anode, with the cathode being positive, while heating the polymer electrolyte fuel cell.

[0012] According to the method for activating a polymer electrolyte fuel cell of (3), the activation of the polymer electrolyte fuel cell is facilitated by applying a voltage between the cathode and the anode.

[0013] (4) A method for activating a polymer electrolyte fuel cell having an electrode membrane structure in which an anode and a cathode are arranged opposite each other via a solid polymer membrane, the method comprising heating the polymer electrolyte fuel cell at a set temperature set within a predetermined range, and then, with the heating stopped, supplying a humidified hydrogen-containing gas to the anode and supplying a humidified oxygen-containing gas or a humidified nitrogen-containing inert gas to the cathode.

[0014] According to the method for activating a polymer electrolyte fuel cell (4), after the polymer electrolyte fuel cell is heated to activate it, the heating is stopped and then a humidified hydrogen-containing gas is supplied to the anode and a humidified oxygen-containing gas or a humidified nitrogen-containing inert gas is supplied to the cathode. This makes it possible to efficiently supply water vapor to both the anode and the cathode without pressurizing the humidified hydrogen-containing gas, the humidified oxygen-containing gas, or the humidified nitrogen-containing inert gas. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a method for activating a polymer electrolyte fuel cell in a shorter time. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing an activation treatment apparatus that can be used in an activation method for a polymer electrolyte fuel cell according to one embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing an example of a state during activation of a polymer electrolyte fuel cell by a method for activating a polymer electrolyte fuel cell according to an embodiment of the present invention; [Figure 3] 10 is a schematic diagram showing another example of a state during activation of a polymer electrolyte fuel cell by a method for activating a polymer electrolyte fuel cell according to one embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] 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.

[0018] FIG. 1 is a block diagram showing an activation treatment apparatus that can be used in an activation method for a polymer electrolyte fuel cell according to one embodiment of the present invention.

[0019] The activation treatment device 100 shown in Fig. 1 is a device for activating a fuel cell stack 10s. The fuel cell stack 10s contains a plurality of solid polymer fuel cells 10.

[0020] The activation treatment device 100 includes an anode electrode side gas supply device 20 , a cathode electrode side gas supply device 30 , a power supply 40 , a heating device 50 , and a voltmeter 60 .

[0021] The anode-side gas supply device 20 includes a humidifier 21. The anode-side gas supply device 20 is a device for pressurizing and supplying a humidified hydrogen-containing gas to the anode of the polymer electrolyte fuel cell 10. The cathode-side gas supply device 30 includes a humidifier 31. The cathode-side gas supply device 30 is a device for pressurizing and supplying a humidified oxygen-containing gas or a humidified nitrogen-containing inert gas to the cathode of the polymer electrolyte fuel cell 10.

[0022] The power supply 40 is connected to the fuel cell stack 10s and is a device for applying a voltage between the cathode and anode of the solid polymer fuel cell unit 10 during activation processing. The heating device 50 is a device for heating the solid polymer fuel cell unit 10 to a predetermined temperature. The voltmeter 60 is a device for measuring the output voltage of the solid polymer fuel cell unit 10. The state of the fuel cell stack 10s can be monitored based on the output voltage measured by the voltmeter 60.

[0023] Next, a method for activating a polymer electrolyte fuel cell according to one embodiment of the present invention using the activation treatment device 100 will be described.

[0024] [First embodiment] In the first embodiment of the activation method for a polymer electrolyte fuel cell, a heating device 50 is used to heat the fuel cell stack 10s to a set temperature. The set temperature is preferably set within a range of 100°C to 300°C, more preferably 100°C to 200°C, and even more preferably 100°C to 150°C. In this embodiment, while the fuel cell stack 10s is being heated, a humidified hydrogen-containing gas produced by the anode-side gas supply device 20 is pressurized and supplied to the anode of the polymer electrolyte fuel cell 10, and a humidified oxygen-containing gas or humidified nitrogen-containing inert gas produced by the cathode-side gas supply device 30 is pressurized and supplied to the anode of the polymer electrolyte fuel cell 10. Examples of the hydrogen-containing gas include hydrogen-containing gas and hydrogen-nitrogen mixed gas. Examples of the oxygen-containing gas include air, pure oxygen gas, and oxygen-nitrogen mixed gas. Examples of the humidified nitrogen-containing inert gas include an inert gas containing nitrogen but not air or pure oxygen gas.

[0025] If the humidified gases (humidified hydrogen-containing gas, humidified oxygen-containing gas, or humidified nitrogen-containing inert gas) are supplied to the polymer electrolyte fuel cell 10 while the fuel cell stack 10s is being heated, the relative humidity of the humidified gases may decrease, making it difficult for the anode and the anode to be activated by water vapor. For this reason, in this embodiment, the humidified gases are pressurized before being supplied to the polymer electrolyte fuel cell 10. The pressure of each humidified gas is preferably in the range of 0 kPaG to 8952 kPaG, more preferably 0 kPaG to 1464 kPaG, and even more preferably 0 kPaG to 375 kPaG. Furthermore, to prevent a decrease in humidity due to an increase in the temperature of each humidified gas when supplied to the polymer electrolyte fuel cell 10, the humidified gases may be heated to a preset temperature set by heating the fuel cell stack 10s, and the dew point of each humidified gas may be adjusted to the preset temperature.

[0026] In this embodiment, while the fuel cell stack 10s is heated, a voltage varying within a predetermined range may be applied between the cathode and anode of the polymer electrolyte fuel cell 10, with the cathode being positive. The voltage application conditions may be, for example, potential scanning within a potential range set within a range of 0.01 V to 1.0 V at a cycle set within a range of 10 seconds to 60 seconds. Applying a voltage facilitates the activation of the polymer electrolyte fuel cell 10. The voltage application may be performed continuously or intermittently.

[0027] In this embodiment, the supply of the humidified hydrogen-containing gas to the anode and the supply of the humidified oxygen-containing gas or the humidified nitrogen-containing inert gas to the cathode may be continuous or intermittent. Also, the gas supplied to the cathode may be switched intermittently between the humidified oxygen-containing gas and the humidified nitrogen-containing inert gas.

[0028] 2 is a schematic diagram showing an example of a state during activation of a polymer electrolyte fuel cell by a method for activating a polymer electrolyte fuel cell according to one embodiment of the present invention, in which a humidified oxygen-containing gas is supplied to the cathode.

[0029] As shown in FIG. 2, a solid polymer fuel cell 10 has a membrane electrode structure in which an anode 12 and a cathode 15 are arranged opposite each other with a solid polymer membrane 11 interposed therebetween. The anode 12 includes an anode catalyst layer 13 in contact with the solid polymer membrane 11 and an anode gas diffusion layer 14 arranged on the side of the anode catalyst layer 13 opposite the solid polymer membrane 11. The cathode 15 includes a cathode catalyst layer 16 in contact with the solid polymer membrane 11 and a cathode gas diffusion layer 17 arranged on the side of the cathode catalyst layer 16 opposite the solid polymer membrane 11. The voltage applied between the anode 12 and the cathode 15 during activation is regulated by a voltage regulator 41. The voltage regulator 41 is connected to a power source 40.

[0030] The humidified hydrogen-containing gas supplied to the anode electrode 12 passes through the anode-side gas diffusion layer 14 and moves to the anode-side catalyst layer 13. In the anode-side catalyst layer 13, the hydrogen (H2) in the humidified hydrogen-containing gas reduces and removes deposits on the surface of the catalyst (Pt), activating the catalyst and converting them into protons (H + ), and the electrons generated at this time move to the cathode side through an external circuit. The protons move to the cathode side catalyst layer 16 by a hydrogen pump. The protons that have moved to the cathode side catalyst layer 16 receive electrons and combine with oxygen to produce water. The water vapor (H2O) in the humidified hydrogen-containing gas moistens the anode side catalyst layer 13. By moistening the anode side catalyst layer 13, a proton path in the anode side catalyst layer 13 is formed, making it easier for protons to move to the solid polymer membrane 11. Furthermore, the water (H2O) in the humidified hydrogen-containing gas moves to the solid polymer membrane 11 and moistens the solid polymer membrane 11.

[0031] The humidified oxygen-containing gas supplied to the cathode electrode 15 passes through the cathode-side gas diffusion layer 17 and moves to the cathode-side catalyst layer 16. The water vapor (H2O) in the humidified oxygen-containing gas activates the catalyst by removing deposits on the surface of the catalyst (Pt) and wetting the cathode-side catalyst layer 16. The oxygen (O2) in the humidified oxygen-containing gas is converted into protons (H + ) reacts with the catalyst to form water (HO). When humidified nitrogen-containing inert gas is supplied to the cathode 15, the humidified nitrogen-containing inert gas passes through the cathode-side gas diffusion layer 17 and moves to the cathode-side catalyst layer 16. The water vapor (HO) from the humidified nitrogen-containing inert gas removes deposits from the surface of the catalyst (Pt) and moistens the catalyst layer, thereby activating the catalyst.

[0032] Fig. 3 is a schematic diagram showing an example of the state during activation of a polymer electrolyte fuel cell by a method for activating a polymer electrolyte fuel cell according to one embodiment of the present invention. Fig. 3 is the same as Fig. 2 except that a humidified nitrogen-containing inert gas is supplied to the cathode, so the same parts are given the same reference numerals and their explanations are omitted.

[0033] The hydrogen (H2) in the humidified hydrogen-containing gas supplied to the anode electrode 12 is converted into protons (H + ), which is transferred to the cathode-side catalyst layer 16 by a hydrogen pump. The protons that have transferred to the cathode-side catalyst layer 16 receive electrons, generating hydrogen (H2). The humidified nitrogen-containing inert gas supplied to the cathode electrode 15 passes through the cathode-side gas diffusion layer 17 and transfers to the cathode-side catalyst layer 16. The water vapor (H2O) from the humidified nitrogen-containing inert gas removes deposits from the surface of the catalyst (Pt) and moistens the cathode-side catalyst layer 16, thereby activating the catalyst.

[0034] In this manner, the polymer electrolyte fuel cell 10 is activated. The end of the activation process can be determined by the output voltage measured by the voltmeter 60.

[0035] According to the method for activating a polymer electrolyte fuel cell of this embodiment configured as described above, the fuel cell stack 10s is heated to a high temperature of 100°C or higher using the heating device 50, while a humidified hydrogen-containing gas is supplied to the anode 12 and a humidified oxygen-containing gas or a humidified nitrogen-containing inert gas is supplied to the cathode 15. This promotes desorption of impurities from the catalyst and wetting of the anode catalyst layer 13, the cathode catalyst layer 16, and the polymer electrolyte membrane 11 with water vapor, thereby facilitating catalyst activation. Furthermore, since the humidified hydrogen-containing gas, the humidified oxygen-containing gas, or the humidified nitrogen-containing inert gas is pressurized, water vapor can be efficiently supplied to the anode 12 and the cathode 15. This allows the polymer electrolyte fuel cell 10 to be activated in a shorter time.

[0036] [Second embodiment] In the second embodiment of the method for activating a polymer electrolyte fuel cell, the fuel cell stack 10s is heated to a set temperature using a heating device 50. The set temperature is preferably set within a range of 100°C to 300°C, more preferably 100°C to 200°C, and even more preferably 100°C to 150°C. In this embodiment, heating by the heating device 50 is stopped after the set temperature is reached. With heating stopped, humidified gas is supplied to the anode and cathode of the fuel cell stack 10s. Because the temperature of the fuel cell stack 10s drops when heating is stopped, even if the pressure when supplying humidified gas to the anode and cathode is lower than in the first embodiment, water vapor can be efficiently supplied to each of the anode and cathode. Therefore, in this embodiment, the humidified gas supplied to the anode and cathode does not need to be pressurized. The humidified gas supplied to the anode and cathode is the same as in the first embodiment. The humidified gas may be supplied to the anode and cathode continuously or intermittently. The humidified gas supplied to the cathode may be intermittently switched between a humidified oxygen-containing gas and a humidified nitrogen-containing inert gas. Furthermore, as in the first embodiment, the cathode of the polymer electrolyte fuel cell 10 may be positive, and a voltage varying within a predetermined range may be applied between the cathode and anode.

[0037] According to the method for activating a polymer electrolyte fuel cell of this embodiment, the fuel cell stack 10s is heated to activate the polymer electrolyte fuel cell cells 10, and then heating is stopped before supplying a humidified hydrogen-containing gas to the anode and a humidified oxygen-containing gas or a humidified nitrogen-containing inert gas to the cathode. This allows water vapor to be efficiently supplied to the anode and cathode without pressurizing the humidified hydrogen-containing gas, the humidified oxygen-containing gas, or the humidified nitrogen-containing inert gas. Gas may also be supplied to the anode and the cathode while the fuel cell stack 10s is being heated. [Example]

[0038] [Example 1] The polymer electrolyte fuel cell is subjected to activation treatment under the following conditions until the desired cell characteristics are obtained. (i) Heating temperature of polymer electrolyte fuel cell: 120°C (heated until activation process is completed) (ii) Humidified hydrogen-containing gas: hydrogen-nitrogen mixed gas, gas temperature when supplied to the cathode was 120°C (dew point: 120°C), pressure was 98 kPaG. (iii) Humidified oxygen-containing gas: oxygen-nitrogen mixed gas, gas temperature when supplied to the anode was 120°C (dew point: 120°C), gas pressure was 98 kPaG. (iv) Voltage application conditions: After holding at 0.03 V for 10 seconds, potential scanning from 0.03 V to 0.9 V was repeated for 30 seconds.

[0039] [Example 2] The activation treatment of the solid polymer fuel cell was carried out in the same manner as in Example 1, except that heating was stopped when the temperature of the solid polymer fuel cell reached 120°C and the pressure of the humidified hydrogen-containing gas and the humidified oxygen-containing gas was set to normal pressure.

[0040] By performing the activation treatment of the polymer electrolyte fuel cells of Examples 1 and 2, the time required for the polymer electrolyte fuel cells to be activated is shortened compared to when the polymer electrolyte fuel cells are heated at 120°C and supplied with humidified hydrogen-containing gas and humidified oxygen-containing gas at atmospheric pressure. [Explanation of symbols]

[0041] 10. Polymer electrolyte fuel cell 10s fuel cell stack 11 Solid polymer membrane 12 Anode 13 Anode side catalyst layer 14 Anode side gas diffusion layer 15 Cathode 16 Cathode side catalyst layer 17 Cathode side gas diffusion layer 20 Anode side gas supply device 21 Humidifier 30 Cathode electrode side gas supply device 31 Humidifier 40 Power supply 41 Voltage Regulator 50 Heating device 60 Voltmeter 100 Activation treatment device

Claims

1. A method for activating a polymer electrolyte fuel cell having a membrane electrode structure in which an anode and a cathode are arranged opposite each other with a polymer electrolyte membrane interposed therebetween, comprising: A method for activating a polymer electrolyte fuel cell, comprising: heating the polymer electrolyte fuel cell at a set temperature set within a predetermined range; supplying a humidified hydrogen-containing gas under pressure to the anode; and supplying a humidified oxygen-containing gas or a humidified nitrogen-containing inert gas under pressure to the cathode.

2. 2. The method for activating a polymer electrolyte fuel cell according to claim 1, wherein the humidified hydrogen-containing gas is heated to the set temperature, and the humidified oxygen-containing gas is heated to the set temperature.

3. 3. The method for activating a polymer electrolyte fuel cell according to claim 1, further comprising applying a voltage varying within a predetermined range between the cathode and the anode, with the cathode being positive, while heating the polymer electrolyte fuel cell.

4. A method for activating a polymer electrolyte fuel cell having a membrane electrode structure in which an anode and a cathode are arranged opposite each other with a polymer electrolyte membrane interposed therebetween, comprising: A method for activating a polymer electrolyte fuel cell, comprising heating the polymer electrolyte fuel cell at a set temperature set within a predetermined range, and then, with the heating stopped, supplying a humidified hydrogen-containing gas to the anode and supplying a humidified oxygen-containing gas or a humidified nitrogen-containing inert gas to the cathode.

Images