Collector and electrochemical cell stack

Abstract

To provide a collector having a passage structure capable of supplying a uniform gas while maintaining a collection property in an effective electrolytic region, and an electrochemical cell stack.SOLUTION: A collector comprises a flow passage connecting a gas supply side end portion which is provided in a metal body for supplying a gas to an electrochemical cell with a gas discharge side end portion which is provided in the metal body for discharging the gas from the electrochemical cell. The flow passage includes: a plurality of first flow passages formed with a first direction, in which the gas flows from the gas supply side end portion to the gas discharge side end portion, defined as a length direction and provided in a second direction which is orthogonal to a lamination direction and different from the first direction; and a second flow passage provided between the gas supply side end portion and the first flow passage and capable of supplying the gas supplied from the gas supply side end portion to the plurality of first flow passages.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to current collectors and electrochemical cell stacks. [Background technology]

[0002] A planar solid oxide electrochemical cell (SOC) is the smallest building block of planar solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs). It generally consists of three layers: an anode, an electrolyte, and a cathode. The high operating temperature (600–1000°C) of SOCs allows for sufficient reaction rates without the need for expensive precious metal catalysts. When an SOC is installed in an SOFC, fuel gas (such as hydrogen or carbon monoxide) is supplied to the anode and air is supplied to the cathode, generating electrical energy through an electrochemical reaction. SOFCs are known for their high power generation efficiency compared to other fuel cell types (such as polymer electrolyte fuel cells and phosphoric acid fuel cells). On the other hand, when an SOC is installed in an SOEC, fuel gas (water vapor) is supplied to the anode and electrical energy is applied to the SOC, generating oxygen and hydrogen from the water vapor through an electrolysis reaction. SOECs are known for their high efficiency compared to conventional water electrolysis. The use of a combination of SOFCs and SOECs as an energy storage system is also being considered. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-57109 Summary of the Invention [Problem to be solved by the invention]

[0004] The SOCs used in SOFCs and SOECs are stacked to increase capacity and form an SOC cell stack. For example, SOCs are stacked with conductive separators in between to form an SOC cell stack. To improve the efficiency of an SOC cell stack, it is necessary to ensure flow paths that can uniformly supply sufficient gas to the area that effectively contributes to the electrochemical reaction or electrolysis reaction (effective electrolysis area). However, if the flow paths are excessively enlarged in order to uniformly supply sufficient gas, the contact area between the effective electrolysis area and surrounding components will decrease, which can worsen current collection. In other words, this could degrade the performance of the SOC cell stack.

[0005] The present invention addresses these circumstances, and the problem that the present invention aims to solve is to provide a current collector and an electrochemical cell stack having a flow path structure that ensures both uniform gas supply in the effective electrolysis area and good current collection. [Means for solving the problem]

[0006] In order to achieve the above object, the current collector of this embodiment has a flow path connecting a gas supply side end provided on the metal body for supplying gas to the electrochemical cell and a gas release side end provided on the metal body for releasing gas from the electrochemical cell, and this flow path is characterized in that it is formed with a first direction in which gas flows from the gas supply side end to the gas release side end as its longitudinal direction, and includes: first flow paths that are provided in multiple directions in a second direction that is perpendicular to the stacking direction and different from the first direction; and second flow paths that are provided between the gas supply side end and the first flow paths and are capable of supplying gas supplied from the gas supply side end to the multiple first flow paths. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is an overall configuration diagram of an electrochemical cell stack 1 according to an embodiment of the present invention. [Figure 2]1A and 1B are cross-sectional views including the air flow paths 5 and 6 of the electrochemical cell stack 1 of this embodiment, where (a) is a cross-sectional view of the electrochemical cell stack 1 as viewed from the P direction in FIG. 1, and (b) is a cross-sectional view of the electrochemical cell stack 1 as viewed from the Q direction in FIG. 1. [Figure 3] 2A and 2B are cross-sectional views including fuel gas flow paths 7 and 8 of an electrochemical cell stack 1 of this embodiment, where (a) is a cross-sectional view of the electrochemical cell stack 1 as viewed from the R direction in FIG. 1, and (b) is a cross-sectional view of the electrochemical cell stack 1 as viewed from the S direction. [Figure 4] 1A and 1B are explanatory diagrams showing the positional relationship when a metal body 20, an anode current collector 30, and a cell 10 are stacked in this order; (a) is an explanatory diagram showing the case where only the metal body 20 is used; (b) is an explanatory diagram showing the case where the anode current collector 30 is stacked on the metal body 20; and (c) is an explanatory diagram showing the case where the cell 10 is stacked on the metal body 20 and the anode current collector 30. [Figure 5] 3A and 3B are explanatory diagrams showing the flow path structure 130 of the anode current collector 30 and the flow path structure 140 of the cathode current collector 40 of this embodiment, where (a) is a cross-sectional view of the electrochemical cell stack 1 as seen from the T direction in FIG. 2, and (b) is a cross-sectional view of the electrochemical cell stack 1 as seen from the U direction in FIG. 3. [Figure 6] 1A and 1B are explanatory diagrams showing the function of the flow path structure 130 of the anode current collector 30 of the present embodiment; (a) is an explanatory diagram showing the flow path structure 230 of the conventional anode current collector 200; (b) is an explanatory diagram showing the flow path structure 130 of the anode current collector 30 of the present embodiment; (c) is an explanatory diagram showing the flow analysis results when the second flow path 30b is set at various percentages; and (d) is an explanatory diagram showing the flow analysis results in the V region in (b). DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, electrochemical cell stacks according to embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments shown below are merely illustrative of embodiments of the present invention and are not intended to limit the scope of the invention. Furthermore, in the drawings referred to in the embodiments, identical parts or parts having similar functions are denoted by the same or similar reference numerals, and their description may be omitted. Furthermore, the dimensional ratios in the drawings may differ from the actual ratios, and some components may be omitted from the drawings.

[0009] An electrochemical cell stack 1 of this embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is an overall configuration diagram of the electrochemical cell stack 1. Fig. 2 is a cross-sectional view including air flow paths 5 and 6 of the electrochemical cell stack 1, and Fig. 2(a) is a cross-sectional view of the electrochemical cell stack 1 as viewed from the P direction in Fig. 1. Fig. 2(b) is a cross-sectional view of the electrochemical cell stack 1 as viewed from the Q direction in Fig. 1. Fig. 3 is a cross-sectional view including fuel gas flow paths 7 and 8 of the electrochemical cell stack 1, and Fig. 3(a) is a cross-sectional view of the electrochemical cell stack 1 as viewed from the R direction in Fig. 1. Fig. 3(b) is a cross-sectional view of the electrochemical cell stack 1 as viewed from the S direction.

[0010] In the following description, an electrochemical cell will be referred to as a cell, and an electrochemical cell stack will be referred to as a cell stack. Furthermore, in the following description, the stacking direction refers to the direction (Z direction) in which cells 10 and metal bodies 20 (described later) are stacked, and when describing this direction or a specific surface, the stacking direction will be used as the reference unless otherwise specified. For example, the top surface refers to the top surface based on the stacking direction, the side surface refers to the side surface based on the stacking direction, and the bottom surface refers to the bottom surface based on the stacking direction. Note that the stacking direction and the direction of gravity do not necessarily coincide here.

[0011] As shown in Figures 1 to 3, the cell stack 1 includes a plurality of cell units 2, each of which includes a cell 10. The cell stack 1 is formed by pressing a stack 3, in which a plurality of cell units 2 are stacked, with end plates 4 from both the top and bottom. The cell unit 2 includes a cell 10, a metal plate 20, an anode current collector 30, an cathode current collector 40, and a separator 50.

[0012] The cell 10 is a flat-plate cell 10 in which an anode 11, an electrolyte 12, and an air electrode 13 are stacked. A chemical reaction occurs when a fuel gas is supplied to the anode 11 and air is supplied to the air electrode 13. The chemical reaction here refers to an electrochemical reaction that generates electrical energy when used as an SOFC, and an electrolysis reaction when used as an SOEC. The fuel gas here refers to hydrogen or carbon monoxide when used as an SOFC, and water vapor when used as an SOEC. While the present embodiment illustrates an example in which the cell 10 is stacked in the order of the anode 11, electrolyte 12, and air electrode 13 from bottom to top, the present invention is not limited to this. For example, the cell 10 may be stacked in the order of the air electrode 13, electrolyte 12, and anode 11 from bottom to top. Furthermore, for example, the cell 10 may be stacked in the order of the anode porous substrate, anode 11, electrolyte 12, and air electrode 13, using an anode porous substrate as a support substrate for the cell 10.

[0013] The metal body 20 accommodates the cells 10. Specifically, as shown in FIGS. 2 and 3, the metal body 20 has cell accommodation sections 20a and 20b formed as recesses in the center, and the cells 10 are accommodated in these accommodation sections 20a and 20b. The metal body 20 is a metal body that electrically connects the cells 10 and spatially separates the cells 10, and is made of a dense and conductive material. Examples of the dense and conductive material include metal and ceramics, and it is desirable that the material has a thermal expansion coefficient close to that of the cells 10. As shown in FIGS. 1 and 2(a), the metal body 20 has air flow channels 5 and 6, which serve as air flow channels, on opposite sides of the cells 10 (opposite sides in the X-axis direction in FIGS. 1 and 2(a)). In this embodiment, the air flow channel 5 indicates the air supply side, and the air flow channel 6 indicates the air discharge side. 1 and 3(a), fuel gas flow paths 7 and 8, which serve as flow paths for fuel gas, are provided in the metal body 20 on opposite sides that are perpendicular to the line segment connecting the air flow paths 5 and 6 and that face each other across the cell 10 (opposite sides in the Y-axis direction in FIGS. 1 and 3(a)). In this embodiment, the fuel gas flow path 7 indicates the fuel gas supply side, and the fuel gas flow path 8 indicates the fuel gas release side. Examples of the metal body 20 include a separator, a support material, or a combination of these.

[0014] The anode current collector 30 is disposed between the anode 11 of the cell 10 and the cell housing portion 20a of the metal body 20. The anode current collector 30 is made of an elastic conductive material. Examples of the conductive material include stainless steel, iron, nickel, titanium, silver, platinum, copper, and alloys thereof. The anode current collector 30 is provided with a flow path connecting the fuel gas flow path 7 and the fuel gas flow path 8. Specifically, the anode current collector 30 is provided with a first flow path 30a and a second flow path 30b, which serve as fuel gas flow paths. The structures of the first flow path 30a and the second flow path 30b will be described later. Note that, although the present embodiment illustrates a case in which the anode current collector 30 is provided with the first flow path 30a and the second flow path 30b, the present invention is not limited to this. For example, similar flow paths may be provided in the metal body 20. In such a modified example, if sufficient contact between the cell 10 and the metal body 20 can be achieved, the fuel electrode current collector 30 may be omitted.

[0015] The air electrode current collector 40 is disposed between the air electrode 13 of the cell 10 and the cell housing portion 20b of the metal body 20. The air electrode current collector 40 is made of an elastic conductive material. Examples of conductive materials include stainless steel, iron, nickel, titanium, silver, platinum, copper, and alloys thereof. The air electrode current collector 40 is provided with a flow path connecting the air flow path 5 and the air flow path 6. Specifically, the air electrode current collector 40 is provided with a first flow path 40a and a second flow path 40b, which serve as air flow paths. The structures of the first flow path 40a and the second flow path 40b will be described later. Note that, although the present embodiment illustrates a case in which the air electrode current collector 40 is provided with the first flow path 40a and the second flow path 40b, this is not limiting. For example, similar flow paths may be provided in the metal body 20. In such a modified example, if sufficient contact between the cell 10 and the metal body 20 can be achieved, the air electrode current collector 40 may be omitted.

[0016] The separator 50 is disposed on the upper surfaces of the electrolyte 12 and the metal body 20 of the cell 10. The separator 50 is made of an insulating and gas-sealing material and provides a seal to prevent gas leakage between the fuel electrode 11 and the air electrode 13 that constitute the same cell 10. As shown in FIGS. 1 and 2(a), the separator 50 has air channels 5 and 6, which serve as air channels, on opposite sides of the cell 10 (opposite sides in the X-axis direction in FIGS. 1 and 2(a)). As shown in FIGS. 1 and 3(a), the separator 50 has fuel gas channels 7 and 8, which serve as fuel gas channels, orthogonal to a line connecting the air channels 5 and 6 and on opposite sides of the cell 10 (opposite sides in the Y-axis direction in FIGS. 1 and 3(a)).

[0017] Any number of cell units 2 having the above structure are stacked to form a stack 3. End plates 4 are placed on both side ends of the stack 3 in the stacking direction (the upper and lower ends in FIG. 1). The end plates 4 are then fixed to the stack 3 by a press mechanism that presses from both sides, or by multiple fastening members such as bolts and nuts (not shown), thereby forming a cell stack 1.

[0018] Next, the anode current collector 30 and the cathode current collector 40 will be further described with reference to FIGS. 4 and 5. FIG. 4 is an explanatory diagram showing the positional relationship when the metal body 20, the anode current collector 30, and the cells 10 are sequentially stacked. FIG. 4(a) is an explanatory diagram showing the case where only the metal body 20 is stacked. FIG. 4(b) is an explanatory diagram showing the case where the anode current collector 30 is stacked on the metal body 20. FIG. 4(c) is an explanatory diagram showing the case where the cells 10 are stacked on the metal body 20 and the anode current collector 30. FIG. 5 is an explanatory diagram showing the flow path structure 130 of the anode current collector 30 and the flow path structure 140 of the cathode current collector 40 of this embodiment. FIG. 5(a) is a cross-sectional view of the cell stack 1 as viewed from the T direction in FIG. 2. FIG. 5(b) is a cross-sectional view of the cell stack 1 as viewed from the U direction in FIG. 3. 4 only describes the case of the anode current collector 30, but the same applies to the cathode current collector 40. In addition, Fig. 5(a) shows positions corresponding to the above-mentioned P direction and Q direction, and Fig. 5(b) shows positions corresponding to the above-mentioned R direction and S direction.

[0019] First, using FIG. 4, the positional relationship when a metal body 20, an anode current collector 30, and a cell 10 are sequentially stacked will be described. As shown in FIG. 4(a), there is a metal body 20 having a housing portion 20a. As shown in FIG. 4(b), the anode current collector 30 is stacked on the upper side of the housing portion 20a of the metal body 20. As shown in FIG. 4(c), the cell 10 is stacked on the upper side of the housing portion 20a of the metal body 20 and on the upper side of the anode current collector 30. In this case, the air electrode 13 constituting the cell 10 is configured to have a smaller area than the anode 11 and electrolyte 12 also constituting the cell 10. The area where the anode 11 and electrolyte 12 overlap with the air electrode 13 constitutes an effective electrolysis area 14, where chemical reactions occur when fuel gas and air are supplied to the anode 11 and air electrode 13, respectively. That is, the effective electrolysis region 14 refers to the region where the anode 11, electrolyte 12, and cathode 13 overlap in the stacking direction (Z direction), where a chemical reaction occurs between the fuel gas supplied to the anode 11 and the air supplied to the cathode 13. As shown in FIG. 4(c), in the region where the effective electrolysis region 14 and the anode current collector 30 overlap, a flow path extending in the fuel gas flow direction (Y direction) is the first flow path 30a. Also, as shown in FIG. 4(c), in the region where the effective electrolysis region 14 and the anode current collector 30 do not overlap, a flow path extending in the direction (X direction) perpendicular to the fuel gas flow direction (Y direction) and the stacking direction (Z direction) is the second flow path 30b.

[0020] Next, the flow channel structures of the anode current collector 30 and the cathode current collector 40 will be described with reference to FIG. 5. As shown in FIG. 5(a), the flow channel structure 130 of the anode current collector 30 has a first flow channel 30a, a second flow channel 30b, and a third flow channel 30c. These flow channels extend in a direction perpendicular to the stacking direction (Z direction) to connect the fuel gas flow channel 7 and the fuel gas flow channel 8. That is, they extend in the Y direction to connect the fuel gas flow channel 7 and the fuel gas flow channel 8. Also, as shown in FIG. 5(a), when the anode current collector 30 is mounted on the metal body 20, a gap region 60 is generated. It is preferable to make this gap region 60 as small as possible to reduce the amount of fuel gas that enters the gap region 60 rather than the first flow channel 30a. 5(a), fuel gas flow channels 7a, 7b or fuel gas flow channels 8a, 8b are provided in the metal body 20 between the fuel gas flow channel 7 or the fuel gas flow channel 8 and the flow channel structure 130 of the anode current collector 30. Note that, although the present embodiment has been described by way of example with respect to a case where four fuel gas flow channels 7b and four fuel gas flow channels 8b are provided in the metal body 20, the present invention is not limited to this case.

[0021] The first flow passages 30a are formed with their longitudinal direction being a first direction (Y direction), which is the direction in which the fuel gas (corresponding to the gas) flows from the fuel gas flow passage 7 (corresponding to the gas supply end) to the fuel gas flow passage 8 (corresponding to the gas release end). A plurality of first flow passages 30a are provided at intervals in a second direction perpendicular to the stacking direction (Z direction) and different from the first direction. A plurality of first flow passages 30a are provided within at least the effective electrolysis region 14 of the anode current collector 30 to supply the fuel gas (corresponding to the gas) supplied to the first flow passages 30a to the effective electrolysis region 14 of the anode 11. In this embodiment, a case is illustrated in which a plurality of first flow passages 30a are provided at intervals in a direction (X direction) perpendicular to both the stacking direction (Z direction) and the first direction (Y direction) within the effective electrolysis region 14. While this embodiment illustrates a case in which the first flow passages 30a are linear, the present invention is not limited to this. For example, the first flow channel 30a may be curved or lightning bolt shaped.

[0022] The second flow passages 30b are provided between the fuel gas flow passage 7 (corresponding to the gas supply side end) and the first flow passages 30a. The second flow passages 30b are provided to supply the fuel gas (corresponding to the gas) supplied from the fuel gas flow passage 7 (corresponding to the gas supply side end) to the plurality of first flow passages 30a. That is, the second flow passages 30b are provided in the range from the fuel gas flow passage 7 (corresponding to the gas supply side end) to the effective electrolysis region 14 of the anode current collector 30 to diffuse the fuel gas (corresponding to the gas) supplied from the fuel gas flow passage 7 (corresponding to the gas supply side end) to the second flow passages 30b in the second direction. In this embodiment, the second flow passages 30b are formed in the range from the fuel gas flow passage 7 (corresponding to the gas supply side end) to the effective electrolysis region 14, with their longitudinal direction being the direction (X direction) perpendicular to both the stacking direction (Z direction) and the first direction (Y direction), as illustrated. In this case, it is desirable that the length of the second flow path 30b in the first direction (Y direction) is at least 3% of the length of the effective electrolysis region 14 in the first direction (Y direction). This will be described in detail later. In this embodiment, the second flow path 30b has been described as having a rectangular structure, but is not limited to this. For example, the second flow path 30b may have a trapezoidal structure or an arched structure as long as it can diffuse the fuel gas.

[0023] The third flow passage 30c is provided between the fuel gas flow passage 8 (corresponding to the gas release side end) and the first flow passage 30a. The third flow passage 30c is provided to release the fuel gas (corresponding to the gas) supplied from the plurality of first flow passages 30a to the fuel gas flow passage 8 (corresponding to the gas release side end). That is, the third flow passage 30c is provided in a range from the end of the anode current collector 30 on the fuel gas flow passage 8 side (corresponding to the gas release side end) to the effective electrolysis region 14 so that the fuel gas (corresponding to the gas) supplied from the plurality of first flow passages 30a to the third flow passage 30c can be merged in the second direction. In this embodiment, the third flow passage 30c is formed in a range from the fuel gas flow passage 8 (corresponding to the gas release side end) to the effective electrolysis region 14, with its longitudinal direction being a direction (X direction) perpendicular to both the stacking direction (Z direction) and the first direction (Y direction). Note that, in this embodiment, the third flow passage 30c has been described with a rectangular structure as an example, but is not limited thereto. For example, the third flow passage 30c may have a trapezoidal structure or an arched structure as long as the fuel gas can be merged. In addition, although the present embodiment has been described by way of example with a structure in which the third flow passage 30c is provided, for example, the first flow passage 30a may be provided up to the fuel gas flow passage 8 without providing the third flow passage 30c.

[0024] As shown in FIG. 5(b), the flow path structure 140 of the cathode current collector 40 includes a first flow path 40a, a second flow path 40b, and a third flow path 40c. These flow paths extend in a direction perpendicular to the stacking direction (Z direction) to connect the air flow path 5 and the air flow path 6. That is, they extend in the X direction to connect the air flow path 5 and the air flow path 6. Also, as shown in FIG. 5(b), when the cathode current collector 40 is installed on the metal body 20, a gap region 60 is generated. This gap region 60 is preferably made as small as possible to reduce the amount of fuel gas that enters the gap region 60 rather than the first flow path 30a. Also, as shown in FIG. 5(b), air flow paths 5a and 5b or air flow paths 6a and 6b are provided in the metal body 20 between the air flow path 5 or air flow path 6 and the flow path structure 140 of the cathode current collector 40. In this embodiment, the case where four air flow paths 5b and four air flow paths 6b are provided in the metal body 20 has been described as an example, but it is not intended to be limited to this case.

[0025] The first flow passages 40a are formed with their longitudinal direction being the first direction (X direction), which is the direction in which air (corresponding to gas) flows from the air flow passage 5 (corresponding to the gas supply side end) to the air flow passage 6 (corresponding to the gas release side end). A plurality of first flow passages 40a are provided at intervals in a second direction perpendicular to the stacking direction (Z direction) and different from the first direction. A plurality of first flow passages 40a are provided within at least the effective electrolysis region 14 of the air electrode current collector 40 to supply the air (corresponding to gas) supplied to the first flow passages 40a to the effective electrolysis region 14 of the air electrode 13. In this embodiment, a case is illustrated in which a plurality of first flow passages 40a are provided at intervals in a direction (Y direction) perpendicular to both the stacking direction (Z direction) and the first direction (X direction) within the effective electrolysis region 14. While this embodiment illustrates a case in which the first flow passages 40a are linear, the present invention is not limited to this. For example, the first flow channel 40a may be curved or lightning bolt shaped.

[0026] The second flow paths 40b are provided between the air flow paths 5 (corresponding to the gas supply side end) and the first flow paths 40a. The second flow paths 40b are provided to supply the air (corresponding to the gas) supplied from the air flow paths 5 (corresponding to the gas supply side end) to the multiple first flow paths 40a. That is, the second flow paths 40b are provided in the range from the air flow paths 5 (corresponding to the gas supply side end) of the cathode current collector 40 to the effective electrolysis region 14 to diffuse the air (corresponding to the gas) supplied from the air flow paths 5 (corresponding to the gas supply side end) to the second flow paths 40b in the second direction. In this embodiment, the second flow paths 40b are formed in the range from the air flow paths 5 (corresponding to the gas supply side end) to the effective electrolysis region 14, with their longitudinal direction being the direction (Y direction) perpendicular to both the stacking direction (Z direction) and the first direction (X direction). In this case, it is desirable that the length of the second flow path 40b in the first direction (X direction) is at least 3% of the length of the effective electrolysis region 14 in the first direction (X direction). This will be described in detail later. In this embodiment, the second flow path 40b has been described using a rectangular structure as an example, but is not limited to this. For example, the second flow path 40b may have a trapezoidal structure or an arched structure as long as it can diffuse air.

[0027] The third flow path 40c is provided between the air flow path 6 (corresponding to the gas release side end) and the first flow path 40a. The third flow path 40c is provided to release the air (corresponding to the gas) supplied from the multiple first flow paths 40a to the air flow path 6 (corresponding to the gas release side end). That is, the third flow path 40c is provided in a range from the end of the air electrode current collector 40 on the air flow path 6 side (corresponding to the gas release side end) to the effective electrolysis region 14 to merge the air (corresponding to the gas) supplied from the multiple first flow paths 40a to the third flow path 40c in the second direction. In this embodiment, the third flow path 40c is formed in a range from the air flow path 6 (corresponding to the gas release side end) to the effective electrolysis region 14, with its longitudinal direction being a direction (Y direction) perpendicular to both the stacking direction (Z direction) and the first direction (X direction). Note that, in this embodiment, the third flow path 40c has been described as having a rectangular structure, but is not limited thereto. For example, the third flow path 40c may have a trapezoidal structure or an arched structure within a range that allows the air flows to merge. Furthermore, although the present embodiment has been described by way of example with a structure in which the third flow path 40c is provided, for example, a structure in which the first flow path 40a is provided up to the air flow path 6 without providing the third flow path 40c may also be used.

[0028] Next, the function of the flow channel structure 130 of the anode current collector 30 will be described using FIG. 6 . FIG. 6 is an explanatory diagram illustrating the function of the flow channel structure 130 of the anode current collector 30 of this embodiment. FIG. 6( a) is an explanatory diagram illustrating the flow channel structure 230 of a conventional anode current collector 200, and FIG. 6( b) is an explanatory diagram illustrating the flow channel structure 130 of the anode current collector 30 of this embodiment. FIG. 6( c) is an explanatory diagram illustrating the results of flow analysis when the second flow channels 30b are set at various percentages, using the ratio of the length of the second flow channels 30b in the first direction (Y direction) to the length of the effective electrolysis region 14 in the first direction (Y direction) as a parameter. FIG. 6( d) is an explanatory diagram illustrating the results of flow analysis in region V in FIG. 6( b). Note that, although only the function of the flow channel structure 130 of the anode current collector 30 will be described below, the same applies to the flow channel structure 140 of the air cathode current collector 40.

[0029] First, we will explain how to interpret Figures 6(c) and 6(d). The horizontal axis of Figure 6(c) indicates the channel number. The channel numbers here correspond to the alphabetical symbols a through s assigned to each flow channel in Figures 6(a) and 6(b). Specifically, symbols a and s indicate the gap region 60 that occurs when the anode current collector 30 is installed on the metal body 20. Symbols b and r indicate the flow channels filled with the anode current collector 30. Symbols c through q indicate the first flow channels 30a. The vertical axis of Figure 6(c) indicates the relative flow rate of the fuel gas flowing through the flow channels corresponding to each symbol. Note that in the following explanation, only numerical values ​​will be used for the relative flow rates. Figure 6(c) shows five data samples, Samples S1 to S5. Specifically, the ratio (hereinafter referred to as ratio P) of the length L2 (see FIG. 6(b)) of the second flow path 30b in the first direction (Y direction) to the length L1 (see FIG. 6(b)) of the effective electrolysis region 14 in the first direction (Y direction) is used as a parameter, and the flow analysis results are shown when the ratio P is set to various values ​​from 1% to 5%. In FIG. 6(d), the flow of fuel gas in region V in FIG. 6(b) is indicated by arrows, and the relative flow velocity of the fuel gas is indicated by a gradation. Note that the dark gradation shown in FIG. 6(d) corresponds to the dark gradation on the side of the relative flow velocity of 0. Furthermore, the numerical values ​​used in the following explanation are based on a data table (not shown) and are rounded to one decimal place. For example, 1.01 is described as approximately 1.0.

[0030] Here, in order to clarify the difference between this embodiment and the conventional one, the flow path structure 230 of the conventional anode current collector 200 will be described as a comparative example, and then the flow path structure 130 of the anode current collector 30 of this embodiment will be described.

[0031] (Effect of Comparative Example) 6(a), in the flow channel structure 230 of the conventional anode current collector 200, a plurality of flow channels are provided at intervals in the X direction, with the longitudinal direction of the flow channels extending in the Y direction to connect the fuel gas flow channel 7 and the fuel gas flow channel 8. That is, in the flow channel structure 230 of the conventional anode current collector 200, only a flow channel corresponding to the first flow channel 30a in the flow channel structure 130 of the anode current collector 30 of this embodiment is provided.

[0032] FIG. 6(c) illustrates the results of fuel gas flow analysis for a conventional anode current collector 200 with a flow channel structure 230. Sample S1 in FIG. 6(c) (where the ratio P is 1%) corresponds to a conventional anode current collector 200 with a flow channel structure 230. As shown in FIG. 6(c), the flow channels corresponding to symbols a and s exhibit a relative flow rate of approximately 2.8, the flow channels corresponding to symbols b and r exhibit a relative flow rate of approximately 0.0, and the flow channels corresponding to symbols c through q exhibit relative flow rates ranging from approximately 1.5 to approximately 6.4. In particular, as shown in FIG. 6(a), the flow channels corresponding to symbols d, h, l, and p among symbols c through q are located relatively close to the respective fuel gas flow channels 7b. Therefore, as shown in FIG. 6(c), the relative flow rates of fuel gas flowing through the flow channels corresponding to symbols d, h, l, and p are relatively high. On the other hand, as shown in FIG. 6(a), the flow paths corresponding to symbols f, j, and n among the flow paths c to q are located relatively far from each fuel gas flow path 7b. Therefore, as shown in FIG. 6(c), the relative flow rates of fuel gas flowing through the flow paths corresponding to symbols f, j, and n are relatively small. Specifically, when focusing on the ratio (hereinafter referred to as ratio Q) of the minimum value to the maximum value of the relative flow rates of fuel gas flowing through each flow path corresponding to symbols c to q, the ratio Q of the minimum value (1.5) to the maximum value (6.4) is approximately 23.3%. Thus, with a flow path structure 230 such as the conventional anode current collector 200, when fuel gas is supplied from the fuel gas flow path 7 to the flow paths corresponding to each first flow path 30a, the fuel gas is less likely to diffuse in the X direction. As a result, the fuel gas may not flow at a uniform relative flow rate through each flow path (symbols c to q) corresponding to the first flow path 30a.

[0033] (Action of this embodiment) In contrast, as shown in Fig. 6(b), the flow path structure 130 of the anode current collector 30 of this embodiment is provided with a first flow path 30a and a second flow path 30b located between the fuel gas flow path 7 and the first flow path 30a. That is, while the flow path structure 230 of the conventional anode current collector 200 is provided with only a flow path corresponding to the first flow path 30a, the flow path structure 130 of the anode current collector 30 of this embodiment is provided with a second flow path 30b between the fuel gas flow path 7 and the first flow path 30a. Note that this embodiment is described by exemplifying a case where the second direction is a direction (X direction) perpendicular to both the stacking direction (Z direction) and the first direction (Y direction), as shown in Fig. 6(b).

[0034] 6(c) will be used to explain the results of fuel gas flow analysis when the flow path structure 130 of the anode current collector 30 of this embodiment is employed. As shown in FIG. 6(c), in adopting the flow path structure 130 of the anode current collector 30 of this embodiment, the inventors performed flow analysis when the percentage P was set to various values ​​from 1% to 5% (samples S1 to S5). Then, based on the results of this flow analysis, the threshold value of the percentage P at which the second flow paths 30b exhibit the effect of diffusing the fuel gas in the X direction was verified. Note that the case where the percentage P is 1% (sample S1) corresponds to the case where the flow path structure 230 of the conventional anode current collector 200 is employed.

[0035] As shown in sample S1 (when the proportion P is 1%), the flow paths corresponding to symbols a and s show a relative flow rate of approximately 2.8, the flow paths corresponding to symbols b and r show a relative flow rate of approximately 0.0, and the flow paths corresponding to symbols c to q show relative flow rates that vary from approximately 1.5 to 6.4.

[0036] Furthermore, as shown in sample S2 (when the proportion P is 2%), the flow paths corresponding to symbols a and s show a relative flow rate of approximately 2.8, the flow paths corresponding to symbols b and r show a relative flow rate of approximately 0.0, and the flow paths corresponding to symbols c to q show relative flow rates that vary between approximately 2.0 and 5.2.

[0037] Furthermore, as shown in sample S3 (when the proportion P is 3%), the flow paths corresponding to symbols a and s show a relative flow rate of approximately 2.8, the flow paths corresponding to symbols b and r show a relative flow rate of approximately 0.0, and the flow paths corresponding to symbols c to q show relative flow rates that vary between approximately 2.5 and 4.3.

[0038] Furthermore, as shown in sample S4 (when the proportion P is 4%), the flow paths corresponding to symbols a and s show a relative flow rate of approximately 2.8, the flow paths corresponding to symbols b and r show a relative flow rate of approximately 0.0, and the flow paths corresponding to symbols c to q show relative flow rates that vary from approximately 3.3 to 4.0.

[0039] Furthermore, as shown in sample S5 (when the proportion P is 5%), the flow paths corresponding to symbols a and s show a relative flow rate of approximately 2.8, the flow paths corresponding to symbols b and r show a relative flow rate of approximately 0.0, and the flow paths corresponding to symbols c to q show relative flow rates that vary between approximately 4.1 and 4.4.

[0040] In particular, in all of samples S1 to S5, as shown in FIG. 6(b), the flow paths corresponding to the symbols d, h, l, and p among the symbols c to q are located relatively close to the respective fuel gas flow paths 7b. Therefore, as shown in FIG. 6(c), the relative flow rates of the fuel gas flowing through the flow paths corresponding to the symbols d, h, l, and p are relatively high. On the other hand, as shown in FIG. 6(b), the flow paths corresponding to the symbols f, j, and n among the symbols c to q are located relatively far from the respective fuel gas flow paths 7b. Therefore, as shown in FIG. 6(c), the relative flow rates of the fuel gas flowing through the flow paths corresponding to the symbols f, j, and n are relatively low.

[0041] In this relationship, as the value of the ratio P increases (as the ratio P increases from 1% to 5%), the variation in the relative flow rates of the fuel gas flowing through the flow paths corresponding to symbols c to q decreases. In other words, as the value of the ratio P increases (as the ratio P increases from 1% to 5%), the fuel gas is diffused in the X direction in the second flow paths 30b and supplied to each of the first flow paths 30a.

[0042] Based on this result, the inventors verified the threshold value of the ratio P at which the second flow passage 30b exhibits the effect of diffusing the fuel gas, focusing on the ratio Q of the minimum value to the maximum value of the relative flow rate of the fuel gas flowing through each flow passage corresponding to the symbols c to q.

[0043] As shown in sample S1, the maximum value of the relative flow rate of fuel gas flowing through each flow path corresponding to symbols c to q is about 6.4, and the minimum value is about 1.5. In other words, the ratio Q of the minimum value to the maximum value is about 23.3%.

[0044] As shown in sample S2, the maximum value of the relative flow rate of the fuel gas flowing through each flow path corresponding to symbols c to q is approximately 5.2, and the minimum value is approximately 2.0. In other words, the ratio Q of the minimum value to the maximum value is approximately 38.9%.

[0045] As shown in sample S3, the maximum value of the relative flow rate of the fuel gas flowing through each flow path corresponding to symbols c to q is about 4.3, and the minimum value is about 2.5. In other words, the ratio Q of the minimum value to the maximum value is about 57.2%.

[0046] As shown in sample S4, the maximum value of the relative flow rate of the fuel gas flowing through each flow path corresponding to symbols c to q is about 4.0, and the minimum value is about 3.3. In other words, the ratio Q of the minimum value to the maximum value is about 81.8%.

[0047] Furthermore, as shown by sample S5, the maximum value of the relative flow rate of fuel gas flowing through each flow path corresponding to symbols c to q is about 4.4, and the minimum value is about 4.1. In other words, the ratio Q of the minimum value to the maximum value is about 93.3%.

[0048] From the above results, the inventors determined that the second flow path 30b exhibits the effect of diffusing fuel gas when the ratio Q of the minimum value to the maximum value of the relative flow rate of fuel gas flowing through each flow path corresponding to symbol c to symbol q is 50% or more. That is, samples S3 to S5 were determined to be cases in which the second flow path 30b exhibits the effect of diffusing fuel gas. This is because, when the ratio Q does not exceed 50%, the variation in the relative flow rate of the flow paths corresponding to symbol c to symbol q constituting the second flow path 30b is more than twice as great, making it difficult to say that the second flow path 30b is functioning to diffuse fuel gas in order to promote more uniform power generation in the effective electrolysis region 14. On the other hand, when the ratio Q exceeds 50%, the variation in the relative flow rate of the flow paths corresponding to symbol c to symbol q constituting the second flow path 30b is kept to less than twice as great, and the inventors determined that the second flow path 30b is at least functioning to achieve the purpose. Therefore, the inventors have determined that it is preferable that the second flow paths 30b be arranged in the range from the fuel gas flow path 7 to the effective electrolysis region 14 of the anode current collector 30 so that the ratio P of the length L2 of the second flow path 30b in the first direction (Y direction) to the length L1 of the effective electrolysis region 14 in the first direction (Y direction) is at least 3%.

[0049] 6(d) shows the flow analysis results when the second flow paths 30b are provided so that the fuel gas flows through each of the first flow paths 30a at a uniform relative flow rate, as in the case of sample S5. As shown in FIG. 6(d), by providing the second flow paths 30b, the fuel gas diffuses through the second flow paths 30b as indicated by the arrows, and flows through each of the first flow paths 30a at a uniform relative flow rate as indicated by the gradation.

[0050] As described above, according to this embodiment, the fuel gas and air are diffused in the second flow paths 30 b and 40 b, and then supplied to the first flow paths 30 a and 40 a, respectively. As a result, it is possible to uniformly supply gas to the effective electrolysis area 14 of the cell 10 while maintaining current collection performance.

[0051] In this embodiment, the second flow path 30b and the second flow path 40b, and the third flow path 30c and the third flow path 40c are described as having no support structures, but this is not limited to this. For example, support structures for supporting the cell stack 1 may be provided in the regions of the second flow path 30b and the second flow path 40b, and the third flow path 30c and the third flow path 40c where the relative flow velocity is relatively low (see FIG. 6(d)). Even in such a modified example, similar actions and effects are achieved.

[0052] Furthermore, although the present embodiment has been described by way of example with reference to a case where the flow channel structure of the present embodiment is applied to both the anode current collector 30 and the cathode current collector 40, the present embodiment is not limited to this case. For example, the flow channel structure of the present embodiment may be applied to either the anode current collector 30 or the cathode current collector 40 depending on the application.

[0053] In addition, in the present embodiment, the metal body 20 and the separator 50 are provided with one each of the air flow paths 5, 6 and the fuel gas flow paths 7, 8, but this is not limitative. For example, a plurality of each of the air flow paths 5, 6 and the fuel gas flow paths 7, 8 may be provided.

[0054] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0055] 1...electrochemical cell stack, 2...cell unit, 3...laminated body, 4...end plate, 5...air flow path, 6...air flow path, 7...fuel gas flow path, 8...fuel gas flow path, 10...electrochemical cell, 11...anode, 12...electrolyte, 13...cathode, 14...effective electrolysis area, 20...metal body, 30...anode current collector, 30a...first flow path, 30b...second flow path, 30c...third flow path, 40...cathode current collector, 40a...first flow path, 40b...second flow path, 40c...third flow path, 50...separator, 60...gap area, 130...flow path structure, 140...flow path structure, 200...anode current collector, 230...flow path structure.

Claims

1. A current collector provided between an electrochemical cell in which a fuel electrode, an electrolyte, and an air electrode are stacked and a metal body, the current collector has a flow path connecting a gas supply side end provided on the metal body for supplying gas to the electrochemical cell and a gas discharge side end provided on the metal body for discharging the gas from the electrochemical cell, The flow path is a first flow path formed with a first direction in which the gas flows from the gas supply side end to the gas release side end as a longitudinal direction, and a plurality of first flow paths provided in a second direction that is perpendicular to the stacking direction and different from the first direction; a second flow path provided between the gas supply side end portion and the first flow path, the second flow path being capable of supplying the gas supplied from the gas supply side end portion to a plurality of the first flow paths; A current collector comprising:

2. 2. The current collector according to claim 1, wherein the first flow path is provided at least in an effective electrolysis region, which is a region where the fuel electrode, the electrolyte, and the air electrode overlap in the stacking direction.

3. 2. The current collector according to claim 1, wherein the length of the second flow path in the first direction is at least 3% of the length in the first direction of an effective electrolysis region, which is a region where the anode, the electrolyte, and the cathode overlap in the stacking direction.

4. 2. The current collector according to claim 1, wherein the second flow path has a support structure for supporting the electrochemical cell and the metal body.

5. 2. The current collector according to claim 1, further comprising a third flow path provided between the gas release side end and the first flow path, the third flow path being capable of releasing the gas supplied from the plurality of first flow paths to the gas release side end.

6. 6. The current collector according to claim 5, wherein the third flow path has a support structure for supporting the electrochemical cell and the metal body.

7. an electrochemical cell comprising an anode, an electrolyte, and a cathode; a metal body that houses the electrochemical cell; an anode current collector provided between the anode and the metal body in the stacking direction; an air electrode current collector provided between the air electrode and the metal body in the stacking direction; Equipped with 7. An electrochemical cell stack, wherein at least one of the anode current collector and the cathode current collector is the current collector according to claim 1.

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