fuel cell

Abstract

This technology utilizes water generated by a fuel cell to suppress the drying up of electrolyte membranes, gas diffusion layers, and other components. [Solution] A power generation unit including an electrolyte membrane and a pair of electrode layers sandwiching the electrolyte membrane, A pair of separators that sandwich the power generation unit, a gas flow path interposed between the power generation unit and the pair of separators, and at least one capillary flow path capable of transporting generated water by capillary action from a first region near a gas outlet that discharges gas from the gas flow path toward a second region near a gas supply port that supplies the gas to the gas flow path, We provide a fuel cell equipped with the following features.

Description

[Technical Field]

[0001] This disclosure relates to fuel cell cells. [Background technology]

[0002] For example, fuel cells such as polymer electrolyte fuel cells (PEFCs) are constructed by stacking a power generation section, which is a membrane electrode assembly gas diffusion layer composite (MEGA) in which a polymer electrolyte membrane is sandwiched between an anode and a cathode, with separators in between. In this type of fuel cell, in order to improve power generation performance, it is necessary to keep the polymer electrolyte membrane in an appropriate moist state to prevent drying up.

[0003] One technique to prevent drying up in polymer electrolyte membranes involves placing a humidifier to suppress drying (Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-210871 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, there is a need for technology that can suppress dryness without requiring additional devices such as humidifiers.

[0006] This specification discloses a technology for suppressing the drying up of electrolyte membranes, gas diffusion layers, etc., by utilizing water generated by a fuel cell.

[0007] The disclosures herein are embodied in a fuel cell. The fuel cell comprises a power generation section including an electrolyte membrane and a pair of electrode layers sandwiching the electrolyte membrane, a pair of separators sandwiching the power generation section, and a gas flow path interposed between at least one of the power generation section and the pair of separators. The fuel cell further comprises at least one capillary flow path capable of transporting generated water by capillary action from a first region near a gas outlet for discharging gas from the gas flow path toward a second region which is near a gas supply port for supplying the gas to the gas flow path.

[0008] This fuel cell allows the generated water to be transported from the first region to the second region by capillary action. The transport of the generated water to the second region humidifies the gas in the second region. The humidified gas flows through the gas channel. As a result, drying up of the electrolyte membrane and other components in contact with the gas channel is effectively suppressed without the need for external humidification. [Brief explanation of the drawing]

[0009] [Figure 1A] This is a perspective view showing an example of a capillary channel in a fuel cell. [Figure 1B] This figure shows a cross-section along the line 1B-1B in Figure 1A. [Figure 2A] This is an exploded perspective view showing another example of the morphology of capillary channels in a fuel cell. [Figure 2B] This is an exploded perspective view showing another example of the morphology of capillary channels in a fuel cell. [Figure 2C] This is an exploded perspective view showing another example of the morphology of capillary channels in a fuel cell. [Figure 3A] This figure shows another example of the morphology of capillary channels in a fuel cell. [Figure 3B] This figure shows another example of the morphology of capillary channels in a fuel cell. [Figure 3C] This figure shows another example of the morphology of capillary channels in a fuel cell. [Figure 3D] This figure shows another example of the morphology of capillary channels in a fuel cell. [Modes for carrying out the invention]

[0010] In addition to the embodiments already described herein, the fuel cell cells disclosed herein may have the following embodiments.

[0011] Another embodiment of the fuel cell may include the first region being positioned below the second region in the direction of gravity. This is advantageous in transferring the generated water to the second region via a capillary channel, as the first region, which is located below the direction of gravity, tends to accumulate generated water.

[0012] Another embodiment of the fuel cell cell comprises at least one capillary channel having a first capillary channel having a first cross-sectional area and a second capillary channel having a second cross-sectional area smaller than the first cross-sectional area, arranged in series, wherein the first capillary channel is located in the first region of the at least one capillary channel and the second capillary channel is located in the second region of the at least one capillary channel. This makes it easier to transfer the generated water from the first region to the second region through capillary action.

[0013] Another embodiment of the fuel cell is such that the first cross-sectional area is 0.1 mm². 2 More than 0.3mm 2 The following applies, and the second cross-sectional area is 0.1 mm². 2 It may be less than this. This allows the generated water to be transported over a sufficient distance (for example, a total of 150 mm or more).

[0014] In another embodiment of the fuel cell, the length of the first capillary channel may be 20 mm or more, and the length of the second capillary channel may be 40 mm or more. This effectively captures the generated water in the first region and increases the pressure loss in the second capillary channel, thereby suppressing the backflow of the generated water due to the gas flow.

[0015] Another aspect of the fuel cell may include at least a part of the at least one capillary flow path in the electrolyte membrane and / or the electrode layer and / or the separator. By using a part of the elements of the fuel cell, the fuel cell can be effectively humidified.

[0016] Hereinafter, the fuel cell disclosed in this specification will be described with reference to the drawings as appropriate. FIG. 1A shows a perspective view of a power generation unit 20 of a fuel cell 2 which is a PEFC (hereinafter, also simply referred to as a cell), and FIG. 1B shows a cross-sectional view taken along line IB-IB thereof.

[0017] FIG. 1A shows the power generation unit 20 of the cell 2. As shown in FIG. 1A, the cell 2 includes an electrolyte membrane 4, a pair of electrode layers 6a and 6b which are an anode and a cathode respectively, and separators 8a and 8b. The electrolyte membrane 4 and the electrode layers 6a and 6b may constitute a membrane electrode assembly 5 (MEA: Membrane Electrode Assembly). Between the separators 8a and 8b, due to the uneven shape of the separators 8a and 8b and the like, a gas flow path 10a for a fuel gas such as hydrogen and a gas flow path 10b for an oxidizing gas such as air or oxygen are formed. Note that a gas diffusion layer (GDL: Gas Diffusion Layer) may be provided for the electrode layers 6a and 6b. In this case, the electrolyte membrane 4 and the electrode layers 6a and 6b may constitute a MEGA (Membrane Electrode And Gas Diffusion Layer Assembly) together with the gas diffusion layer.

[0018] As shown in FIGS. 1A and 1B, in the power generation unit 20, the gas flow paths 10a and 10b supply a fuel gas and an oxidizing gas to the electrode layers 6a and 6b respectively. For example, for the gas flow path 10b of the oxidizing gas, a gas supply path and a gas discharge path (not shown) are connected to the cell 2 respectively.

[0019] As a result, in the power generation unit 20, for example as shown in Figures 1A and 1B, the gas supply section 32 is supplied with oxidizing gas A1 from one side in the parallel direction where the multiple gas flow paths 10b of the power generation unit 20 are arranged in parallel, and oxidizing gas A1 is supplied to the gas flow paths 10b. Also, for example, the gas discharge section 30 is discharged from the downward side in the direction of gravity of the gas supply section 32, and oxidizing gas A2 that has passed through the power generation unit 20 is discharged, and oxidizing gas A2 is discharged from the gas flow paths 10b. The gas discharge section 30 and the gas supply section 32 are examples of the first and second regions in this specification, respectively.

[0020] As shown in Figures 1A and 1B, cell 2 is equipped with a capillary channel 40. The capillary channel 40 is formed within the thickness of the separator 8b, as shown in Figure 1A. The capillary channel 40 is formed to allow the transfer of generated water by capillary action from the gas discharge section 30 to the gas supply section 32.

[0021] The capillary channel 40 shown in Figure 1B directly connects the gas discharge section 30 and the gas supply section 32. That is, the capillary channel 40 has an opening 34 that opens at the gas discharge section 30 and an opening 36 that opens at the gas supply section 32, connecting them. The shape of the capillary channel 40 is not particularly limited. For example, in a dense matrix such as a separator 8b, it can be provided as an elongated through-channel.

[0022] As shown in Figure 1B, the capillary channel 40 is provided with a large-diameter first capillary channel 42 and a smaller-diameter second capillary channel 44 in series. The first capillary channel 42 is formed with a relatively large channel cross-sectional area to facilitate the drawing up of generated water near the gas discharge site 30. The cross-sectional area of ​​the first capillary channel 42 is not particularly limited, but for example, 0.1 mm 2 More than 0.3mm 2The following applies. Within this range, a rise (transfer) of generated water of approximately 50 mm to 100 mm can be expected. The length of the first capillary channel 42 is not particularly limited, but can be set to, for example, 20 mm or more, taking into consideration the estimated amount of generated water and the degree of humidification. This length is set appropriately according to the intended degree of generated water transport.

[0023] The cross-sectional area of ​​the second capillary channel 44 is not particularly limited, but for example, 0.1 mm 2 It is less than this. This is because within this range, a rise (transfer) of generated water of 100 mm or more can be expected. The length of the first capillary channel 42 is not particularly limited, but can be set to, for example, 20 mm or more, taking into consideration the estimated amount of generated water and the degree of humidification. This length is set appropriately according to the intended degree of generated water transfer. The length of the second capillary channel 44 is preferably 40 mm or more. If it is longer than this, the pressure loss in the second capillary channel 44 at the gas supply part 32 is increased, making it difficult for gas to flow in and suppressing the pushback of generated water.

[0024] The cross-sectional shape of the channels of the first capillary channel 42 and the second capillary channel 44 is not particularly limited.

[0025] By providing a capillary channel 40, the generated water from the gas discharge section 30 can be captured, drawn up, and transferred to the gas supply section 32. The generated water that reaches the gas supply section 32 humidifies the oxidizing gas A1, and the humidified oxidizing gas A1 flows through the gas channel 10b. As a result, the electrode layer 6b and electrolyte membrane 4 in contact with the gas channel 10b can be humidified. Furthermore, if the cell 2 is equipped with a gas diffusion layer, the gas diffusion layer can also be humidified.

[0026] Furthermore, in the capillary channel 40, the gas discharge section 30 is positioned lower in the direction of gravity than the gas supply section 32, allowing for effective humidification using the generated water that tends to accumulate lower in the direction of gravity. Since the capillary channel 40 transports the generated water by capillary action, the positional relationship between the gas discharge section 30 and the gas supply section 32 can be set independently of the direction of gravity.

[0027] Furthermore, since the capillary channel 40 is formed within the thickness range of the separator 8b, there is a high degree of freedom in setting the formation location of the capillary channel 40. As shown in Figure 2A, the capillary channel 40a may be formed not inside the separator 8b, but by forming a recess in the separator 8b of cell 2 and shielding the recess with the separator 8a of adjacent cell 2 or a sealing gasket.

[0028] Furthermore, as shown in Figure 2B, a portion of the capillary channel 40b may be formed with an MEA 5 consisting of an electrolyte membrane 4 and an electrode layer 6b. For example, the capillary channel 40b may be formed in a concave shape facing the MEA 5 side in the separator 8b, and the concave portion may be shielded by the MEA 5. In this way, the generated water transferred from the gas discharge section 30 can be diffused and humidified into the electrolyte membrane 4, electrode layer 6b, etc., before reaching the gas supply section 32.

[0029] Furthermore, when a portion of the capillary channel 40b is formed with an MEA 5 consisting of an electrolyte membrane 4 and an electrode layer 6b, the configuration may be such that it does not open at the gas discharge section 30 and the gas supply section 32, as shown in Figure 2C. The generated water can diffuse through the electrolyte membrane 4, electrode layer 6b, etc. Therefore, even without connecting to the gas supply section 32 or the gas discharge section 30, the generated water inside the electrolyte membrane 4, etc., located near the gas discharge section 30 can be transported to the electrolyte membrane 4, etc., located near the gas supply section 32.

[0030] Furthermore, the capillary channel 40 is designed so that the first capillary channel 42 and the second capillary channel 44 have different cross-sectional areas at the gas discharge section 30 and the gas supply section 32, thereby enabling effective capture and transport of the generated water. As shown in Figure 3A, the capillary channel 40c may directly connect the first capillary channel 42 and the second capillary channel 44, which have different cross-sectional areas, or it may be provided with a connection between the first capillary channel 42 and the second capillary channel 44 such that the cross-sectional area gradually changes. This allows for smooth transport of the generated water.

[0031] Furthermore, as shown in Figure 3B, the capillary channel 40d may also include one or more additional first capillary channels 42a, 42b and one or more second capillary channels 44a, 44b between the first capillary channel 42 and the second capillary channel 44. This may allow for the transfer of a large amount of generated water. In this case, it is preferable that the total length of the multiple first capillary channels 42 is 20 mm or more, and the total length of the multiple second capillary channels 44 is 40 mm or more. In addition, the first capillary channels 42a, 42b, etc. of the capillary channel 40d with this configuration may also be provided to extend to the electrolyte membrane 4, electrode layer 6b, etc., and other MEA5. In this case, the generated water in the capillary channel 40 can diffuse to the electrolyte membrane 4, electrode layer 6b, etc., via the first capillary channels 42a, 42b before reaching the gas supply section 32.

[0032] Furthermore, as shown in Figure 3C, the capillary channel 40e may be provided with multiple first capillary channels 42c and 42d arranged in parallel. This may allow for effective capture of generated water near the gas discharge site 30.

[0033] Furthermore, as shown in Figure 3D, multiple capillary channels 40f may be provided in cell 2. This allows the generated water to be transferred in the gas channel 10b from other gas discharge points 30a to other gas supply points 32a.

[0034] In the above description, the gas flow path 10b through which the oxidizing gas A1 in the cell 2 flows has been described. However, for the gas flow path 10a of the fuel gas through which the fuel gas flows, a capillary flow path may be set in the same manner.

[0035] Also, in the above description, a plurality of gas flow paths 10b are provided, but it is not limited thereto. Various patterns of the gas flow path 10b can be set.

[0036] According to the disclosure of the specification, the following aspects are included. [1] A fuel cell, including a power generation part including an electrolyte membrane and a pair of electrode layers sandwiching the electrolyte membrane, a pair of separators sandwiching the power generation part, a gas flow path interposed between at least one of the power generation part and the pair of separators, at least one capillary flow path capable of transferring generated water by capillary action from a first region near a gas discharge port for discharging gas from the gas flow path to a second region near a gas supply port for supplying the gas to the gas flow path, and a fuel cell provided with the same. [2] The fuel cell according to [1], wherein the first region is arranged below the second region in the direction of gravity. [3] The at least one capillary flow path includes a first capillary flow path having a first cross-sectional area and a second capillary flow path having a second cross-sectional area smaller than the first cross-sectional area, arranged in series, the first capillary flow path is arranged in the first region of the at least one capillary flow path, and the second capillary flow path is arranged in the second region of the at least one capillary flow path, the fuel cell according to [1] or [2]. [4] The first cross-sectional area is 0.1 mm 2 or more and 0.3 mm 2 or less, and the second cross-sectional area is less than 0.1 mm, the fuel cell according to [3]. 2 [5] The fuel cell cell according to any one of [1] to [4], wherein the length of the first capillary channel is 20 mm or more, and the length of the second capillary channel is 40 mm or more. [6] The fuel cell cell according to any one of [1] to [6], wherein the portion of the at least one capillary channel is in the electrolyte membrane and / or the electrode layer and / or the separator.

[0037] Although embodiments have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of Symbols]

[0038] 2 fuel cell, 4 electrolyte membrane, 6a, 6b electrode layer, 8a, 8b separator, 10a, 10b gas flow path, 20 power generation section, 30 gas discharge section, 32 gas supply section, 40, 40a, 40b, 40c, 40d, 40e, 40f capillary flow path, 42 first capillary flow path, 44 second capillary flow path, 50 connection section

Claims

1. It is a fuel cell cell, A power generation unit including an electrolyte membrane and a pair of electrode layers sandwiching the electrolyte membrane, A pair of separators that sandwich the power generation unit, A gas flow path interposed between the power generation unit and the pair of separators, A capillary channel capable of transporting generated water by capillary action from a first region near a gas outlet that discharges gas from the gas channel toward a second region near a gas supply port that supplies the gas to the gas channel, A fuel cell equipped with a fuel cell.

2. The fuel cell cell according to claim 1, wherein the first region is positioned lower in the direction of gravity than the second region.

3. The at least one capillary channel comprises a first capillary channel having a first cross-sectional area and a second capillary channel having a second cross-sectional area smaller than the first cross-sectional area, arranged in series. The fuel cell cell according to claim 2, wherein the first capillary channel is located in the first region of the at least one capillary channel, and the second capillary channel is located in the second region of the at least one capillary channel.

4. The first cross-sectional area is 0.1 mm². ２ 0.3mm or more ２ The following applies, and the second cross-sectional area is 0.1 mm². ２ A fuel cell cell according to claim 3, wherein the value is less than [value missing].

5. The fuel cell cell according to claim 4, wherein the length of the first capillary channel is 20 mm or more, and the length of the second capillary channel is 40 mm or more.

6. The fuel cell according to any one of claims 1 to 5, wherein the fuel cell cell comprises a portion of the at least one capillary channel in the electrolyte membrane and / or the electrode layer and / or the separator.

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