JP2021096923A - Fuel battery cell - Google Patents

Abstract

To provide a fuel battery cell excellent in portability.SOLUTION: According to the present invention, there is provided a fuel battery cell which includes an anode catalyst layer, an electrolyte membrane and a cathode catalyst layer in the order, the fuel battery cell including a hydrogen storage member arranged therein.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fuel cell with excellent portability.

The fuel cell can supply hydrogen to the anode and air (oxygen) to the cathode, and can generate electricity by an electrochemical reaction. In Patent Document 1, it is assumed that power is generated by supplying hydrogen to a fuel cell from a hydrogen supply source provided outside the fuel cell. In the present specification, unless otherwise specified, hydrogen and oxygen mean hydrogen gas and oxygen gas, respectively.

Japanese Unexamined Patent Publication No. 2017-16942 JP-A-2017-179345 Patent No. 6402102

However, in the configuration of Patent Document 1, in order to operate the fuel cell, it is necessary to carry an external hydrogen supply source together with the fuel cell, so that the portability is poor.

The present invention has been made in view of such circumstances, and provides a fuel cell with excellent portability.

According to the present invention, there is provided a fuel cell in which an anode catalyst layer, an electrolyte membrane, and a cathode catalyst layer are provided in this order, and a hydrogen storage member is arranged in the fuel cell. ..

In the present invention, the hydrogen storage member is arranged in the fuel cell, and the fuel cell can be operated by using the hydrogen released from the hydrogen storage member. Therefore, the fuel cell can be operated without receiving the supply of hydrogen from an external hydrogen supply source, which is excellent in portability.

Hereinafter, various embodiments of the present invention will be illustrated. The embodiments shown below can be combined with each other.
Preferably, it is the fuel cell cell described above, wherein the hydrogen storage member is a fuel cell cell arranged at a position adjacent to the anode catalyst layer.
Preferably, the fuel cell according to the description, wherein the hydrogen storage member is a gel or solid fuel cell.
Preferably, the fuel cell is described above, and the hydrogen storage member is a sheet-shaped fuel cell.
Preferably, the fuel cell according to the above description, wherein the hydrogen storage member is a fuel cell which is an organic polymer containing a hydroxy group.
Preferably, the fuel cell cell described above is a fuel cell cell in which the space in which the hydrogen storage member is arranged is airtight with respect to the outside of the fuel cell cell during power generation.
Preferably, it is the fuel cell cell described above, wherein the electrolyte membrane is a fuel cell having a structure composed of an aromatic skeleton.
Preferably, the fuel cell described above is a fuel cell in which the electrolyte membrane has an oxygen permeability coefficient of 10 barler or less per unit film thickness.

It is a perspective view of the fuel cell 1 of one Embodiment of this invention. 2A is a cross-sectional view of the catalyst coating film 2 and the support frame 3 in FIG. 1, and FIG. 2B is an enlarged view of a region B in FIG. 2A. It is a perspective view which looked at the anode unit 10 in FIG. 1 from the direction different from FIG. It is a perspective view which saw the cathode unit 20 in FIG. 1 from the direction different from FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The various features shown in the embodiments shown below can be combined with each other. In addition, the invention is independently established for each feature.

1. 1. Configuration of Fuel Cell Cell 1 As shown in FIGS. 1 to 4, the fuel cell 1 of the embodiment of the present invention includes a catalyst coating film 2, a support frame 3, an anode unit 10, and a cathode unit 20. ..

1-1. Catalyst coating film 2 and support frame 3
As shown in FIG. 2, the catalyst coating membrane 2 is configured by coating the anode catalyst layer 2b on one surface of the electrolyte membrane 2a and coating the cathode catalyst layer 2c on the other surface of the electrolyte membrane 2a. The peripheral edge portion 2d of the catalyst coating film 2 is supported by the support frame 3. The electrolyte membrane 2a is a polymer membrane having ionic conductivity, and protons can move from the anode catalyst layer 2b side to the cathode catalyst layer 2c side through the electrolyte membrane 2a.

The electrolyte membrane 2a is, for example, a polymer electrolyte membrane having a structure composed of an aromatic skeleton. Examples of such an electrolyte membrane include those disclosed in Patent Document 2. Specifically, for example, an aromatic ring having a main chain of a plurality of aromatic rings (eg, a benzene ring) having no sulfonic acid group introduced therein. ) And a polymer electrolyte containing a copolymer composed of a hydrophilic segment in which a sulfonic acid group is introduced and the main chain is mainly composed of an aromatic ring, which constitutes the hydrophobic segment. The plurality of aromatic rings are linked by a carbon-carbon direct bond of the aromatic ring constituting the hydrophobic segment, the sulfonic acid group of the hydrophilic segment is directly bonded to the aromatic ring, and the hydrophobic segment and the said. The aromatic ring of the hydrophilic segment is one in which the hydrophobic segment and the aromatic ring constituting the hydrophilic segment are connected by a carbon-carbon direct bond.

The electrolyte membrane 2a preferably has low gas permeability, and more preferably has an oxygen permeability coefficient of 10 barler or less per unit film thickness. The oxygen permeability coefficient per unit film thickness can be determined by the isobaric method.

1-2. Anode unit 10
As shown in FIG. 3, the anode unit 10 includes a hydrogen storage member 11, an anode diffusion member 12, an anode gasket 13, an anode separator 14, an anode current collector plate 15, and an anode housing 16.

The hydrogen storage member 11 is arranged at a position adjacent to the anode catalyst layer 2b. The hydrogen storage member 11 is a member capable of switching between storage and release of hydrogen, and may be composed of either an organic substance or an inorganic substance, and is preferably composed of an organic polymer from the viewpoint of light weight and handleability. The hydrogen storage member 11 is preferably a member capable of reversibly switching between storage and release of hydrogen. The hydrogen storage member 11 may be a single material or a combination of a plurality of materials. Switching between storage and release of hydrogen is preferably performed by changing the temperature or pressure, depending on the type and properties of the hydrogen storage member 11.

In one example, hydrogen is stored in the hydrogen storage member 11 by bringing hydrogen into contact with the hydrogen storage member 11 at the first temperature, and the hydrogen storage member 11 is brought to a second temperature higher than the first temperature to bring the hydrogen storage member 11 to a second temperature. Releases hydrogen from. The temperature difference between the first temperature and the second temperature is, for example, 20 to 120 ° C., preferably 20 to 80 ° C., specifically, for example, 20, 30, 40, 50, 60, 70, 80, The temperature is 90, 100, 110, 120 ° C., and may be within the range between any two of the numerical values exemplified here. The second temperature is, for example, 40 to 150 ° C., preferably 60 to 100 ° C., specifically, for example, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140. , 150 ° C., and may be within the range between any two of the numerical values exemplified here.

In another example, hydrogen is stored in the hydrogen storage member 11 by bringing hydrogen into contact with the hydrogen storage member 11 at the first pressure, and the hydrogen storage member 11 is set to a second pressure having a lower hydrogen partial pressure than the first pressure. This causes hydrogen to be released from the hydrogen storage member 11.

The hydrogen storage member 11 is preferably a gel or solid, preferably on a sheet. This is because such a form is easy to handle. The hydrogen storage member 11 is, for example, an organic polymer containing a hydroxy group (preferably containing a hydroquinoid structure). Examples of such a polymer include those disclosed in Patent Document 3. Hydrogen is released when the hydrogen atom of the hydroxy group is separated from the oxygen atom, and hydrogen is stored when the hydrogen atom is bonded to the oxygen atom. The hydroxy group is preferably bonded to a carbon atom, and hydrogen is released when the hydroxy group bonded to the carbon atom becomes a carbonyl group, and the hydrogen atom is bonded to the oxygen atom of the carbonyl group to form a hydroxy group. Hydrogen is stored by.

In one example, the organic polymer constituting the hydrogen storage member 11 contains a hydroquinoid structure and is either (i) a polyvinyl alcohol or a derivative of a modified polyvinyl alcohol, or (ii) ethylene, styrene, norbornene, allylamine, methacryl. At least one functional group selected from the group consisting of a functional group derived from at least one compound of acid and acrylic acid and at least one functional group of phenylene methylene, phenylene ether and phenylene ester. Included in the repeating unit. The hydroquinoid structure is preferably derived from at least one compound selected from the group consisting of benzoquinol, naphthoquinol and anthraquinol. A catalyst such as an iridium complex may be mixed to promote the hydrogen storage reaction and the generation reaction.

The thickness of the hydrogen storage member 11 is, for example, 1 to 20 mm, preferably 3 to 10 mm. If the hydrogen storage member 11 is too thin, the hydrogen storage amount may be insufficient, and if it is too thick, the entire fuel cell may become excessively thick. When the thickness of the hydrogen storage member 11 is thin, a plurality of hydrogen storage members may be laminated and used.

The anode diffusion member 12 is arranged so as to surround the hydrogen storage member 11 at a position adjacent to the anode catalyst layer 2b. In another expression, the hydrogen storage member 11 is arranged in the opening 12a provided in the anode diffusion member 12. The size of the opening 12a is not particularly limited as long as the hydrogen storage member 11 can be arranged. The anode diffusion member 12 is a member that diffuses an anode gas containing hydrogen, and is made of, for example, a porous material. By providing the anode diffusion member 12, efficient diffusion of the anode gas becomes possible.

The anode gasket 13 is arranged so as to surround the anode diffusion member 12 at a position adjacent to the support frame 3. In another expression, the hydrogen storage member 11 and the anode diffusion member 12 are arranged in the opening 13a provided in the anode gasket 13. The anode gasket 13 is made of, for example, a rubber sheet and has a function of preventing leakage of the anode gas (hydrogen).

The anode separator 14 is arranged at a position adjacent to the hydrogen storage member 11, the anode diffusion member 12, and the anode gasket 13, and is arranged between these members and the anode current collector plate 15, and is arranged in a space through which the anode gas flows and outside the space. Separate the space. In the present embodiment, the fuel cell 1 has a single cell configuration, but may have a laminated cell configuration in which a plurality of cells are laminated. In this case, the anode separator 14 separates the space through which the anode gas flows from the space through which the cathode gas or cooling water containing oxygen flows. The anode separator 14 is preferably formed of a conductive material such as metal. The anode separator 14 includes an anode gas inlet 14a and an anode gas outlet 14b, and a flow path 14c connecting them. The flow path 14c can be omitted if it is unnecessary.

The anode current collector plate 15 is arranged at a position adjacent to the anode separator 14. The anode current collector plate 15 is formed of a conductive material (such as metal). The anode current collector plate 15 is provided with an anode gas inlet 15a and an anode gas outlet 15b communicating with the anode gas inlet 14a and the anode gas outlet 14b. The anode current collector plate 15 has a protruding portion 15d having an opening 15c, and an external terminal is connected to this portion so that the electric power generated by the fuel cell 1 can be taken out.

The anode housing 16 is arranged at a position adjacent to the anode current collector plate 15. The anode housing 16 has an anode gas inlet 16a and an anode gas outlet 16b communicating with the anode gas inlet 15a and the anode gas outlet 15b.

It is preferable that the anode gas inlet 16a and the anode gas outlet 16b are closed while hydrogen is taken out from the hydrogen storage member 11 to generate electricity. As a result, the space in which the hydrogen storage member 11 is arranged becomes airtight with respect to the outside of the fuel cell 1, and hydrogen generated from the hydrogen storage member 11 is suppressed from leaking to the outside to effectively generate electricity. it can. On the other hand, when hydrogen is stored in the hydrogen storage member 11, the anode gas containing hydrogen is supplied from the anode gas inlets 16a, 15a and 14a, and at least a part of the hydrogen in the anode gas is absorbed by the hydrogen storage member 11. After that, the anode gas is discharged from the anode gas outlets 14b, 15b, 16b. As a result, hydrogen can be stored in the hydrogen storage member 11.

1-3. Cathode unit 20
As shown in FIG. 4, the cathode unit 20 includes a cathode diffusion member 22, a cathode gasket 23, a cathode separator 24, a cathode current collector plate 25, and a cathode housing 26.

The cathode diffusion member 22 is arranged at a position adjacent to the cathode catalyst layer 2c. The cathode diffusion member 22 is a member that diffuses a cathode gas containing oxygen, and is made of, for example, a porous material. By providing the cathode diffusion member 22, efficient diffusion of the cathode gas becomes possible.

The cathode gasket 23 is arranged so as to surround the cathode diffusion member 22 at a position adjacent to the support frame 3. In another expression, the cathode diffusion member 22 is arranged in the opening 23a provided in the cathode gasket 23. The cathode gasket 23 is made of, for example, a rubber sheet and has a function of preventing leakage of the cathode gas (oxygen).

The cathode separator 24 is arranged at a position adjacent to the cathode diffusion member 22 and the cathode gasket 23, and is arranged between these members and the cathode current collector plate 25 to separate the space through which the cathode gas flows and the space outside the cathode gas. In the present embodiment, the fuel cell 1 has a single cell configuration, but may have a stacked cell configuration in which a plurality of cells are stacked. In this case, the cathode separator 24 separates the space through which the cathode gas flows from the space through which the anode gas or the cooling water flows. The cathode separator 24 is preferably made of a conductive material such as metal. The cathode separator 24 includes a cathode gas inlet 24a and a cathode gas outlet 24b, and a flow path 24c connecting them. The flow path 24c can be omitted if it is unnecessary.

The cathode current collector plate 25 is arranged at a position adjacent to the cathode separator 24. The cathode current collector plate 25 is made of a conductive material (such as metal). The cathode current collector plate 25 is provided with a cathode gas inlet 25a and a cathode gas outlet 25b that communicate with the cathode gas inlet 24a and the cathode gas outlet 24b. The cathode current collector plate 25 has a protruding portion 25d having an opening 25c, and an external terminal is connected to this portion so that the current generated by the fuel cell 1 can be taken out.

The cathode housing 26 is arranged at a position adjacent to the cathode current collector plate 25. The cathode housing 26 has a cathode gas inlet 26a and a cathode gas outlet 26b communicating with the cathode gas inlet 25a and the cathode gas outlet 25b.

When generating power in the fuel cell 1, the cathode gas containing oxygen is supplied from the cathode gas inlets 26a, 25a, 24a, and the cathode gas after at least a part of the oxygen in the cathode gas becomes water by the reaction is generated. It is discharged from the cathode gas outlets 24b, 25b, 26b.

2. Operation method of the fuel cell 1 The fuel cell 1 can store hydrogen in the hydrogen storage member 11 in the hydrogen storage step, and can generate power by using the hydrogen extracted from the hydrogen storage member 11 in the power generation step.

In the hydrogen storage step, the anodic gas containing hydrogen is supplied from the anodic gas inlets 16a, 15a, 14a, and the anodic gas is brought into contact with the hydrogen storage member 11 to bring the anodic gas into contact with the hydrogen storage member 11 so as to be arranged in the fuel cell 1. It can store hydrogen. At this time, it is preferable to adjust the temperature so that the hydrogen storage member 11 has a temperature suitable for hydrogen storage. The temperature can be controlled, for example, by controlling the heater and the cooling water.

Instead of providing the hydrogen storage step, a hydrogen storage member 11 in a state in which hydrogen is stored in advance outside the fuel cell 1 is prepared, and a step of exchanging the hydrogen storage member 11 with the hydrogen storage member 11 in the fuel cell 1 is performed. You may. In this case, the hydrogen storage member 11 having stored hydrogen can be arranged in the fuel cell 1 simply by replacing the hydrogen storage member 11, so that the fuel cell 1 can be operated efficiently.

In the power generation step, hydrogen may be taken out from the hydrogen storage member 11 before the start of power generation, or hydrogen may be taken out from the hydrogen storage member 11 while generating power. Hydrogen can be taken out from the hydrogen storage member 11 by raising the temperature or reducing the pressure depending on the type and properties of the hydrogen storage member 11. The pressure can be adjusted, for example, by controlling a pump or a pressure reducing valve.

In the power generation step, air may be supplied as the cathode gas, or oxygen may be supplied. Since air can be supplied using a blower member such as a fan, it is suitable for enhancing the portability of the fuel cell 1.

A power generation experiment was conducted using hydrogen taken out from the hydrogen storage member 11 arranged in the fuel cell 1 by the following method.

1. 1. Preparation of Experimental Fuel Cell Cell The fuel cell 1 of Examples 1 and 2 having the configurations shown in FIGS. 1 to 4 was manufactured under the conditions shown in Table 1. Examples 1 and 2 have different electrolyte membranes as shown in Table 1.

Details of the various members in Table 1 are as follows.
TEC10E50E: Made by Tanaka Kikinzoku Kogyo, carbon-supported platinum catalyst Nafion NRE-212: Made by Sigma-Aldrich Japan LLC, Nafion membrane (oxygen permeation coefficient per unit film thickness is about 20 barler)
SPP-QP: Polymer electrolyte membrane having the structure of chemical formula (1) (oxygen permeability coefficient per unit film thickness is about 2 barler)

29BC: Graphite fiber non-woven fabric manufactured by SGL Carbon (thickness about 200 μm)

As the hydrogen storage member 11, an organic polymer (including an iridium complex catalyst) having a structure of the chemical formula (2) and having a thickness of 5 mm was used. As the anode diffusion member 12, 25 sheets having an opening having a shape for accommodating the hydrogen storage member 11 were stacked and used.

2. Power generation experiment A power generation experiment was conducted under the conditions shown in Table 2. Since the storage and release of hydrogen in the hydrogen storage member 11 is promoted by the presence of water, the power generation experiment was performed with a relative humidity of 100%. In period 1, hydrogen was supplied as an anode gas at a cell temperature of 30 ° C., and hydrogen was stored in the hydrogen storage member 11. In period 2, the anode gas was changed to nitrogen, and the hydrogen remaining in the space where the hydrogen storage member 11 was arranged was removed. In period 3, the space in which the hydrogen storage member 11 is arranged was allowed to stand in a closed state. In period 4, hydrogen was released from the hydrogen storage member 11 by raising the cell temperature to 80 ° C. In period 5, oxygen was supplied as the cathode gas. During this period, no resistor is connected between the current collector plates 15 and 25, so no power is generated. In period 6, a resistor was connected between the current collector plates 15 and 25 to generate electricity.

3. 3. Experimental results Table 3 shows the results of the power generation experiment.

3-1. Power generation time In both Examples 1 and 2, the cell voltage immediately after the start of power generation was 0.8 V. The cell voltage gradually decreased with the passage of time. Table 3 shows the time required for the cell voltage to reach 0 V. The power generation experiment was conducted 10 times. The results of the 1st, 5th, and 10th times are shown in Table 3.

Since the mass of the hydrogen storage member 11 used is different between Examples 1 and 2, a value obtained by normalizing the power generation time with the mass of the hydrogen storage member 11 is calculated so as to easily compare the power generation performance, and 1 g. Table 3 shows the power generation time per hit. As shown in Table 3, in Example 2, the power generation time per gram was longer than that in Example 1.

When the anode potential, cathode potential, and ohm resistance were measured to investigate the cause of the gradual decrease in cell voltage over time, the cathode potential and ohm resistance hardly changed during power generation. It was found that the anode potential increased significantly during power generation. This result indicates that the change in cell voltage is an increase in the anode potential as the amount of hydrogen available for power generation decreases.

3-2. Hydrogen utilization rate The hydrogen utilization rate was calculated when the current density was 1,5,10 mA cm- ^{2 according to the following formula.} The results are shown in Table 3. As shown in Table 3, the hydrogen utilization rate in Example 2 was higher than that in Example 1. Moreover, the smaller the current density, the higher the hydrogen utilization rate.

Hydrogen utilization rate (%) = 100 x (amount of electricity that can actually be generated) / (amount of electricity that can theoretically be generated from hydrogen stored in the hydrogen storage member 11)

3-3. Discussion As described above, in Example 2, the power generation time was longer and the hydrogen utilization rate was higher than in Example 1. As a result, since the gas permeability of the electrolyte membrane used in Example 2 is lower than the gas permeability of the electrolyte membrane used in Example 1, the hydrogen generated in the hydrogen storage member 11 efficiently generates electricity. It is probable that it was used.

1: Fuel cell cell 2: Cathode coating film 2a: Electrolyte film 2b: Cathode catalyst layer 2c: Cathode catalyst layer 2d: Peripheral portion 3: Support frame 10: Anode unit 11: Hydrogen storage member 12: Anode diffusion member 12a: Opening 13: Cathode gasket 13a: Opening 14: Cathode separator 14a: Cathode gas inlet 14b: Cathode gas outlet 14c: Flow path 15: Cathode current collector plate 15a: Cathode gas inlet 15b: Cathode gas outlet 15c: Opening 15d: Protruding part 16 : Anodic housing 16a: Anodic gas inlet 16b: Anode gas outlet 20: Cathode unit 22: Cathode diffusion member 23: Cathode gasket 23a: Opening 24: Cathode separator 24a: Cathode gas inlet 24b: Cathode gas outlet 24c: Flow path 25 : Cathode current collector plate 25a: Cathode gas inlet 25b: Cathode gas outlet 25c: Opening 25d: Protruding part 26: Cathode housing 26a: Cathode gas inlet 26b: Cathode gas outlet

Claims (8)

A fuel cell in which an anode catalyst layer, an electrolyte membrane, and a cathode catalyst layer are provided in this order.
A fuel cell in which a hydrogen storage member is arranged in the fuel cell. The fuel cell according to claim 1.
The hydrogen storage member is a fuel cell in which the hydrogen storage member is arranged at a position adjacent to the anode catalyst layer. The fuel cell according to claim 1 or 2.
The hydrogen storage member is a fuel cell, which is a gel or a solid. The fuel cell according to any one of claims 1 to 3.
The hydrogen storage member is a fuel cell in the form of a sheet. The fuel cell according to any one of claims 1 to 4.
The hydrogen storage member is a fuel cell, which is an organic polymer containing a hydroxy group. The fuel cell according to any one of claims 1 to 5.
A fuel cell in which the space in which the hydrogen storage member is arranged is airtight with respect to the outside of the fuel cell during power generation. The fuel cell according to any one of claims 1 to 6.
The electrolyte membrane is a fuel cell having a structure composed of an aromatic skeleton. The fuel cell according to any one of claims 1 to 7.
The electrolyte membrane is a fuel cell in which the oxygen permeability coefficient per unit film thickness is 10 barler or less.

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