fuel cells

Abstract

The object of this invention is to provide a fuel cell that can suppress the parasitic resistance of the fuel cell and ensure the effective area of ​​the fuel cell. In the fuel cell of this invention, the conductive substrate is configured to contact the porous support layer at a position where no through holes are formed. The boundary between the conductive substrate and the porous support layer at the aforementioned position is configured to allow gas to flow in a direction orthogonal to the extension direction of the aforementioned through holes (refer to FIG1).

Description

Technical Field

[0001] This invention relates to fuel cells. Prior Technology

[0002] In recent years, fuel cells, a type of power generation system that uses fuels such as hydrogen without emitting carbon dioxide, have gradually attracted attention. A fuel cell is constructed by sandwiching an electrolyte between two electrodes: an anode and a cathode. Fuel gas such as hydrogen is supplied to the anode side, and oxygen-containing gas such as air is supplied to the cathode side, thereby generating electricity. The fuel cell disclosed in Patent Document 1 is constructed by sequentially layering electrode layers / electrolyte layers / electrode layers on a metal support frame. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] US20220271317A1 Summary of the Invention

[0004] [The problem the invention aims to solve] Patent Document 1 describes a metal support frame divided into a dense region and a porous region. The porous region has through-holes with a diameter of 10-150 μm to supply gas to the electrode layer directly above. The thinner the electrolyte membrane of a fuel cell, the greater the power generation. However, if the through-holes are blocked, the fuel cell cannot operate. Therefore, when the through-hole diameter is 10 μm, it is difficult to form a thin electrolyte membrane of, for example, less than 1 μm.

[0005] To form a thin-film electrolyte layer with a thickness of less than 1 μm, it is preferable to use a substrate with a through-pore size of less than 300 nm. For example, anodic aluminum oxide (AAO) can have a through-pore size of less than 300 nm, serving as a porous support layer. Electrode layers / electrolyte layers are then sequentially deposited on this layer to form a thin-film fuel cell cell. While AAO is an insulating material, the formation of a metal film within the through-pores creates an electrical connection between the front and back surfaces. Therefore, by placing it on a conductive substrate such as a metal support frame, the generated electricity can be extracted to the outside. However, in this case, the conductive substrate can block part of the through-pores in the porous support layer, reducing the effective area of ​​the fuel cell cell. For example, the metal support frame in Patent Document 1 has a maximum porosity of 60%. If a thin-film cell using a porous support layer is placed on this frame, the effective area will be reduced by 40%.

[0006] If the through-holes in the porous support layer are not used, for example, if a portion of the lower electrode is exposed to the surface and a conductive part is placed there, then the through-holes in the porous support layer will not be blocked, and the power generated by the fuel cell can still be extracted. However, such a conductive path will result in power loss due to the resistance of the lower electrode sheet, thus hindering the expansion of the fuel cell area.

[0007] The present invention was made in view of the above-mentioned problems, and its purpose is to provide a fuel cell that can suppress the parasitic resistance of the fuel cell and ensure the effective area of ​​the fuel cell. [Methods for solving problems]

[0008] In the fuel cell of the present invention, the conductive substrate is configured to contact the porous support layer at a position where no through-hole is formed, and the boundary between the conductive substrate and the porous support layer at the aforementioned position is configured to allow gas to flow in a direction orthogonal to the extension direction of the aforementioned through-hole. [Effects of the Invention]

[0009] According to the present invention, the parasitic resistance of the fuel cell can be suppressed, and the effective area of ​​the fuel cell can be ensured. Other issues, structures, and effects not described above will be explained in the following description of embodiments. Simple Explanation of the Diagram

[0010] [Figure 1] is a cross-sectional view showing the structure of the fuel cell 1 according to Embodiment 1. [Figure 2] is an enlarged cross-sectional view of the porous support layer 4. [Figure 3A] is an enlarged perspective view of the surface of the conductive substrate 2. [Figure 3B] is a magnified view of the area near surface flow path 10 in Figure 3A. [Figure 4A] is a side cross-sectional view showing the current path. [Figure 4B] is a cross-sectional view showing the current path when the porous support layer 4 is an insulating material. [Figure 5A] is a cross-sectional view showing a construction example of a fuel cell stack 500. [Figure 5B] is a diagram showing the breakdown of each layer of the fuel cell stack 500. [Figure 6] is a cross-sectional view showing a construction example of the fuel cell stack 600 according to Embodiment 2. [Figure 7] is a cross-sectional view showing a construction example of the fuel cell 1 according to Embodiment 3. [Figure 8] is a cross-sectional view showing a structural example of fuel cell 1 according to embodiment 4. [Figure 9A] is a diagram illustrating the definition of the depth of the surface flow path 10. [Figure 9B] is a diagram illustrating the definition of the depth of the surface flow path 10. [Figure 10] is a cross-sectional view showing a construction example of the fuel cell 1000 according to Embodiment 5. [Figure 11] is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 6. [Figure 12] is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 7. [Figure 13] is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 8. [Figure 14] is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 9. [Figure 15] is a cross-sectional view showing a construction example of the fuel cell 1 according to Embodiment 10. [Figure 16] is a cross-sectional view showing a construction example of the fuel cell 1 according to embodiment 11. [Figure 17] is a cross-sectional view showing a construction example of the fuel cell 1 according to embodiment 12. [Figure 18] is a cross-sectional view showing a structural example of the fuel cell 1 according to embodiment 13. Implementation

[0011] <Implementation Method 1> Figure 1 is a cross-sectional view showing the structure of a fuel cell 1 according to Embodiment 1 of the present invention. The fuel cell 1 is formed by mounting at least one unit cell 3 (hereinafter also referred to as cell) on a conductive substrate 2.

[0012] The unit cell 3 is a fuel cell cell composed of a porous support layer 4, a first electrode layer 5, an electrolyte layer 6 (solid electrolyte layer), and a second electrode layer 7. The electrolyte layer 6 is sandwiched between the first electrode layer 5 and the second electrode layer 7.

[0013] To fabricate high-output-density cells, when the first electrode layer 5, electrolyte layer 6, and second electrode layer 7 are thin films of, for example, 1 μm or less, the porous support layer 4 serves to support the entire cell 3. As shown in Figure 2 (described later), the porous support layer 4 has a porous structure with a second through-hole 8 oriented in the Z direction, allowing gas to reach the first electrode layer 5. The Z direction is the direction from the bottom surface of the conductive substrate 2 towards the surface of the second electrode layer 7. The plane formed with the Z direction as its normal is called the XY plane; the direction perpendicular to the Z direction is called the X direction; and the direction perpendicular to both the Z and X directions is called the Y direction.

[0014] The first electrode layer 5 is formed by a film deposition process such as sputtering, but it is not formed entirely on the porous support layer 4. Instead, a region without the first electrode layer 5 is set on the outer periphery of the porous support layer 4. The first electrode layer 5 is porous to supply gas to the electrolyte layer 6. If the first electrode layer 5 were formed entirely on the porous support layer 4, gas leakage might occur between the top and bottom of the unit cell 3. By retaining the outer periphery of the porous support layer 4 and covering the outer periphery with a dense electrolyte layer 6, gas leakage can be prevented.

[0015] When the first electrode layer 5 functions as the anode of a fuel cell, it is supplied with fuel gases such as hydrogen. In this case, the first electrode layer 5 is composed of materials such as nickel and yttrium-stabilized zirconium oxide ceramic metal. The electrolyte layer 6 is composed of materials such as yttrium-stabilized zirconium oxide with an 8% yttrium content. If the electrolyte layer 6 is formed into a thin film of less than 1 μm using a film-forming process such as sputtering, high output density power generation can be obtained. When the first electrode layer 5 is the anode, the second electrode layer 7 is the cathode, and it is composed of materials such as platinum, platinum and GDC (Gadolinium-Doped Ceria), or LSC ((La,Sr)CoO3). By having a porous structure, the oxidant gas can reach the electrolyte layer 6. Alternatively, if the second electrode layer 7 is made of a material that is conductive to both oxygen ions (O2-) and electrons, a porous structure is not necessary. When the first electrode layer 5 is the cathode and the second electrode layer 7 is the anode, oxidant gas is supplied to the first electrode layer 5 and fuel gas is supplied to the second electrode layer 7.

[0016] The conductive substrate 2 is a conductor, ideally a stainless steel alloy or similar material that maintains constant mechanical strength at high temperatures. Furthermore, the porous support layer 4 is preferably made of a material with a similar coefficient of thermal expansion. For example, if the porous support layer 4 is alumina, the coefficient of thermal expansion of the conductive substrate 2 is preferably below 10×10⁻⁶ / K (linear expansion), and more preferably around 7~8×10⁻⁶ / K (linear expansion).

[0017] The conductive substrate 2 is formed using laser processing technology or similar methods, and has a first through-hole 9. This first through-hole 9 has a larger area than the second through-hole 8 of the porous support layer 4, potentially being more than 100 times larger. The distance between the first through-holes 9 is comparable to the width of the first through-hole 9 of the conductive substrate, and can be more than 100 times the width of the second through-hole 8. Therefore, on the surface where the conductive substrate 2 contacts the porous support layer 4, multiple second through-holes 8 of the porous support layer 4 are arranged between the first through-holes 9 of the conductive substrate 2.

[0018] The surface of the conductive substrate 2 has a surface flow path 10 (this configuration directs gas flow in a direction orthogonal to the extending direction of the second through-hole 8). The detailed configuration of the surface flow path 10 will be explained later. Through the surface flow path 10, the gas supplied from the first through-hole 9 of the conductive substrate 2 is supplied to the second through-hole 8 of the porous support layer 4, and then to the first electrode layer 5.

[0019] In a prior art structure without surface flow path 10, the portion of the second through-hole 8 where the first through-hole 9 is not formed at the contact point between the conductive substrate 2 and the porous support layer 4 will be blocked. This prevents gas flow in that area, reducing the effective area for power generation within the unit cell 3. In contrast, by providing surface flow path 10 on the surface of the conductive substrate 2, gas can be supplied to the second through-hole 8 even where the first through-hole 9 is not formed. However, surface flow path 10 is not provided at the ends of the unit cell 3. This is to prevent fuel gas and oxidant gas from mixing via surface flow path 10.

[0020] Figure 2 is an enlarged cross-sectional view of the porous support layer 4. The porous support layer 4 has multiple second through-holes 8 extending in the Z direction. The diameter of the second through-holes 8 is preferably less than 300 nm. This is because if the diameter is too large, the film thickness must be increased accordingly to block the layer formed above the second through-holes 8.

[0021] Figure 3A is an enlarged perspective view of the surface of the conductive substrate 2. Figure 3B is a more enlarged view of the vicinity of the surface flow path 10. A portion of the gas reaching the surface of the conductive substrate 2 through the first through-hole 9 enters the surface flow path 10 and travels in the X or Y direction. As shown in Figure 3B, the top of the conductive substrate 2 has a porous support layer 4, so the gas enters the second through-hole 8 of the porous support layer 4 and travels in the Z direction to the first electrode layer 5. Figure 3A only shows four gas paths, but in reality, the gas diffuses in all directions, branching off in the X or Y direction along the way, and diffuses to the entire surface of the conductive substrate 2. The tiny spaces of the surface flow path 10 are completely filled with gas. During power generation, the gas is consumed, causing a decrease in gas concentration and creating a concentration difference. Therefore, the gas is supplied from the area with higher concentration (the bottom of the first through-hole 9). The gas does not move from a lower concentration area to a higher concentration area, so the movement of the gas in the X and Y directions within the surface flow path 10 does not violate this principle. For simplicity, Figure 3B only shows the divergence in the X and Z directions, but in reality, it also diverges in all XYZ directions.

[0022] Figure 4A is a cross-sectional view showing the current path. Here, we illustrate an example where the first electrode layer 5 is used as the anode. In Figure 4A, the porous support layer 4 is a conductive material. Fuel gas flows through the surface flow path 10 of the conductive substrate 2 and the second through-hole 8 of the porous support layer 4, passing through the porous first electrode layer 5. At the interface with the electrolyte layer 6, it reacts with oxygen ions moving through the electrolyte layer 6 to generate water vapor and electrons. The water vapor is discharged to the outside through the second through-hole 8, the surface flow path 10, and the first through-hole 9 (not shown). Electrons are extracted from the first electrode layer 5 through the porous support layer 4 and the conductive substrate 2 and sent to the power-consuming load.

[0023] Figure 4B is a cross-sectional view showing the current path when the porous support layer 4 is an insulating material. When the porous support layer 4 is an insulating material, there must be an electrical connection from the surface of the porous support layer 4 to the back surface. This can be achieved, for example, by providing a through-hole wiring 11 inside the second through-hole 8. The flow of gas or oxygen ions is the same as in Figure 4A. Since the porous support layer 4 is an insulating material, electrons generated at the interface between the first electrode layer 5 and the electrolyte layer 6 will travel to the through-hole wiring 11 and be extracted to the outside via the through-hole wiring 11 and the conductive substrate 2. As shown in Figure 4B, if the through-hole wiring 11 is formed to extend to the back surface of the porous support layer 4, an electrical connection between the through-hole wiring 11 and the conductive substrate 2 can be ensured.

[0024] Figure 5A is a cross-sectional view showing a structural example of a fuel cell stack 500. The fuel cell stack 500 is composed of a fuel cell 1, a separator 501, a cell gasket 502, a current collector 503, an upper electrode plate 504, a lower gasket 505, an upper gasket 506, a bottom frame 507, a top frame 508, a support column 509, and a locking member 510. The fuel cell stack 500 is assembled by sequentially stacking the bottom frame 507, the lower gasket 505, the separator 501, the fuel cell 1, the upper electrode plate 504, the upper gasket 506, and the top frame 508 from below. The bottom frame 507 and the top frame 508 have openings for the support column 509 to pass through. The two ends of the support column 509 are machined to fit the shape of the locking member 510. For example, if the locking member 510 is a nut, the support column 509 is provided with threads of the same shape as the locking member 510. The entire fuel cell stack 500 is locked from the top and bottom by locking the locking member 510.

[0025] This structure prevents the fuel gas and oxidant gas used for the operation of the fuel cell 1 from leaking to the outside of the fuel cell stack 500. The separator 501 and the conductive substrate 2 are joined by welding or other methods to prevent gas leakage to the outside, while also electrically connecting the separator 501 to the first electrode layer 5 of the fuel cell 1. At this time, the separator 501 is shaped with a concave portion forming inward except at the end, thereby forming a gas flow path 511 to supply gas to the first through hole 9 of the conductive substrate 2. Furthermore, the upper electrode plate 504 is electrically connected to the second electrode layer 7 via the current collector 503, so the electricity generated by the fuel cell 1 can be extracted to the outside.

[0026] Figure 5B is an exploded view of the layers of the fuel cell stack 500. The conductive substrate 2 has a first gas inlet 2a, a first gas outlet 2b, a second gas inlet 2c, and a second gas outlet 2d. The first gas is either a fuel gas or an oxidant gas, and the second gas is an oxidant gas if the first gas is a fuel gas, and a fuel gas if the first gas is an oxidant gas.

[0027] Similar to the conductive substrate 2, (a) the separator 501 has a first gas inlet 501a, a first gas outlet 501b, a second gas inlet 2c, and a second gas outlet 501d; (b) the cell pad 502 has a first gas inlet 502a, a first gas outlet 502b, a second gas inlet 502c, and a second gas outlet 502d; and (c) the upper electrode plate 504 has a first gas inlet 504a, a first gas outlet 504b, a second gas inlet 504c, and a second gas outlet 504d.

[0028] At least one of the lower gasket 505 and the upper gasket 506 is provided with a first gas inlet 505a or 506a, a first gas outlet 505b or 506b, a second gas inlet 505c or 506c, and a second gas outlet 505d or 506d; thus, the first gas and the second gas can be supplied to the unit cell 3 from the bottom frame 507 or the top frame 508. Gas can also be supplied from both the bottom frame 507 and the top frame 508. The example in Figure 5B shows a structure in which all four sides of all layers have inlets and outlets. The following example illustrates the case where the first gas is supplied from the first gas inlet 505a of the lower gasket and the second gas is supplied from the second gas inlet 506c of the upper gasket.

[0029] The first gas supplied from the first gas inlet 505a of the lower gasket flows into the first gas inlet 501a of the separator. The first gas inlet 501a of the separator has a notch, so the first gas passes over the separator 501 and proceeds to the first gas outlet 501b. The location through which this first gas passes is the gas flow path 511 in FIG. 5A, supplying the first gas to the back side of the unit cell 3 via the first through hole 9 of the conductive substrate 2. At this time, the surface of the conductive substrate 2 is formed with a surface flow path 10 as shown in FIG. 3A and FIG. 3B, supplying the first gas to the second through hole 8 of the porous support layer 4 via the surface flow path 10, thereby suppressing the loss of power generation area. The first gas supplied to the second through hole 8 is supplied to the first electrode layer 5, and by making the first electrode layer 5 a porous structure, it can be further supplied to the interface between the first electrode layer 5 and the electrolyte layer 6.

[0030] The first gas arriving at the first gas outlet 501b of the separator will go to the first gas outlet 505b of the lower gasket and be discharged to the outside of the fuel cell stack 500 via the bottom frame 507. Furthermore, as shown in Figure 6 later, in the case of multiple fuel cells 1 being stacked, the first gas will sequentially pass through the first gas inlet 2a of the conductive substrate and the first gas inlet 502a of the cell gasket to the upper part.

[0031] The second gas supplied from the second gas inlet 506c of the upper gasket flows into the second gas inlet 504c of the upper electrode plate 504. The second gas then proceeds to the second gas inlet 502c of the cell gasket. The second gas inlet 502c of the cell gasket has a notch, so the gas passes over the unit cell 3 on the conductive substrate 2 and proceeds to the second gas outlet 502d of the cell gasket. The unit cell 3 has a current collector 503. If the current collector 503 has a mesh structure or a gas-permeable structure, the second gas can be supplied to the second electrode layer 7 located on the surface of the unit cell 3. Furthermore, by making the second electrode layer 7 a porous structure, the second gas can be supplied to the interface between the second electrode layer 7 and the electrolyte layer 6.

[0032] The second gas that arrives at the second gas outlet 501d of the cell unit gasket will pass through the second gas outlet 504d of the upper electrode plate 504 to the second gas outlet 506d of the upper gasket, and will be discharged to the outside of the fuel cell stack 500 via the roof frame 508.

[0033] <Implementation Method 2> Figure 6 is a cross-sectional view showing a construction example of the fuel cell stack 600 according to Embodiment 2 of the present invention. The fuel cell stack 600 is composed of a unit stack 601, an upper electrode plate 504, a lower gasket 505, an upper gasket 506, a bottom frame 507, a top frame 508, a support column 509, and a locking member 510. The unit stack 601 refers to the area formed by the fuel cell 1, the separator 501, the cell gasket 502, and the current collector 503. The structure of the fuel cell 1 is the same as in Embodiment 1.

[0034] The difference from Embodiment 1 is that the unit stack 601 is constructed by stacking in the longitudinal direction. This allows two unit cells 3 to be connected in series, increasing the output voltage of the entire stack. Furthermore, by repeatedly stacking the unit stack 601, more than three can be connected in series, and the output voltage of the entire stack increases depending on the number of stacks. When multiple stacks are stacked as described above, surface flow paths 10 are provided on the surface of the conductive substrate 2, similar to Embodiment 1, to suppress the loss of power generation area.

[0035] <Implementation Method 3> Figure 7 is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 3 of the present invention. As shown in Figure 3B, in Embodiment 1, the second through hole 8 of the porous support layer 4 and the surface flow path 10 of the conductive substrate 2 are aligned in XY coordinates. However, the size of the second through hole 8 or the surface flow path 10 is around several hundred nanometers, and aligning their positions or repeating the length can sometimes be quite difficult.

[0036] Therefore, in Embodiment 3, as shown in Figure 7, the width of the protrusion of the surface flow path 10 (La in the figure) is shorter than the width of the second through hole 8 of the porous support layer 4 (Lb in the figure), so that the second through hole 8 will not be completely blocked. In this way, the loss of power generation area can be suppressed. The other structures are the same as in Embodiment 1.

[0037] <Implementation Method 4> Figure 8 is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 4 of the present invention. The surface flow path 10 of the conductive substrate 2 does not necessarily have to be rectangular; for example, it can also be an aggregate of microparticles. Other structures are the same as in Embodiment 1.

[0038] The gaps between the microparticles are completely filled with gas. During power generation, this gas is consumed, and the concentration decreases near the interface between the first electrode layer 5 and the electrolyte layer 6. As a result, the gas within the surface flow path 10 diffuses into the gaps between the microparticles. If the diameter of each microparticle is smaller than the width of the second through-hole 8, it will not block the second through-hole 8, thus preventing loss of power generation area. The material of these microparticles can be, for example, nickel. By forming a paste using an organic solvent, and then coating and sintering, the surface flow path 10, composed of microparticle aggregates, can be formed on the surface of the conductive substrate 2.

[0039] Figures 9A and 9B illustrate the definition of the depth of the surface flow path 10 in this invention. Figure 9A shows the case where the surface of the conductive substrate 2 has been processed, and Figure 9B shows the case where, as in Embodiment 4, a layer such as an aggregate of microparticles is used as the surface flow path 10. In either case, the depth of the surface flow path 10 is defined as the length corresponding to the length D indicated by the arrow in the figures, that is, the length from the position closest to the porous support layer 4 to the bottom surface of the porous support layer 4 within the range where there is no gas flow path in the conductive substrate 2 in the XY direction.

[0040] When the surface flow path 10 is very shallow, insufficient gas supply will occur. However, deepening the surface flow path 10 is difficult to process in the case of Figure 9A, and requires multiple layer formations in the case of Figure 9B, both of which have drawbacks. Therefore, the depth of the surface flow path 10 should be kept as low as possible. For example, in the case of Figure 9A, it is 1.0~3.5 micrometers, and in the case of Figure 9B, it is 1.5~12 micrometers. In the case of Figure 9A, the processing difficulty is mainly determined by the aspect ratio D / W of the depth D and width W, and this aspect ratio is preferably in the range of 3~100. In the case of Figure 9B, the necessary depth of the surface flow path 10 is related to the porosity of the microparticle aggregate, etc. (the ratio of the volume of an individual void to the total volume containing the void). If the porosity is too low, it will affect gas diffusion; if the porosity is too high, it will be affected by parasitic resistance. Therefore, a porosity in the range of 30~70% is preferred.

[0041] <Implementation Method 5> Figure 10 is a cross-sectional view showing a structural example of the fuel cell 1000 according to Embodiment 5 of the present invention. In Embodiment 5, a current collector 1001 is inserted between the conductive substrate 2 and the separator 501. When current is to be extracted from the separator 501 in the X or Y direction, there are three current paths in the XY direction: (a) the XY direction within the conductive substrate 2, (b) the XY direction within the separator 501, and (c) the XY direction within the current collector 1001. In this way, compared with the case where there is only two current paths without the current collector 1001, the parasitic resistance of the current path can be reduced.

[0042] As shown in Figure 6, when multiple unit cells 3 are connected in series, electrons move from the conductive substrate 2 through the current collector 1001 and the separator 501 to the lower layer in the Z direction. In this case, by stacking and locking the fuel cells 1000 as a unit, a fuel cell stack is assembled. The other structures are the same as in Embodiment 2.

[0043] Without the current collector 1001, if the fuel cell 1000 is connected in series as shown in Figure 6, the current will flow sequentially through the conductive substrate 2, the sidewall of the separator 501, and the bottom surface of the separator 501. This current path is longer than with the current collector 1001, so the parasitic resistance is greater. The thinner the separator 501, the more significant this increase in parasitic resistance becomes, thus hindering the miniaturization of the fuel cell 1000. By configuring the current collector 1001, such parasitic resistance can be suppressed.

[0044] The current collector 1001 is the same as the current collector 503, and adopts a mesh structure to avoid hindering gas diffusion. Materials such as nickel can be used, but if the first gas is an oxidizing gas, materials with strong oxidation resistance, such as silver, are preferred.

[0045] In the stack structure of the fuel cell 1000, the top and bottom layers draw current from the outer periphery of the metal substrate, so it is best to thicken the metal substrate according to the current required. As long as there is a current collector, the middle layer does not need to be thickened.

[0046] <Implementation Method 6> Figure 11 is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 6 of the present invention. In this embodiment, a noble metal layer 1101 is disposed on the surface of the conductive substrate 2, and a noble metal layer 1102 is disposed on the back side of the porous support layer 4. The other structures are the same as in Embodiment 1.

[0047] When the first gas is an oxidizing gas, the conductive substrate 2 or the porous support layer 4 may be oxidized, increasing the contact resistance with the porous support layer 4. Even when the first gas is a fuel gas, the power generation operation will produce water vapor, which may also cause the conductive substrate 2 or the porous support layer 4 to be oxidized. Therefore, forming a noble metal layer on both surfaces of the conductive substrate 2 and the porous support layer 4 that are in contact with each other can prevent the increase in contact resistance. In Figure 11, the noble metal layer 1101 is formed only on the protrusion of the surface flow path 10, but it can also be formed all the way to the inner sidewall or bottom of the surface flow path 10. Furthermore, when the porous support layer 4 is an insulating material, the wiring 11 inside the through hole shown in Figure 4B can also serve as the noble metal layer 1102.

[0048] <Implementation Method 7> Figure 12 is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 7 of the present invention. In Embodiment 1, when the porous support layer 4 is an insulating material, the electrical connection between the front and back sides of the fuel cell 1 is achieved by providing a through-hole wiring 11 on the inner wall of the second through-hole 8. In contrast, this embodiment provides a through electrode 1201 on a portion of the second through-hole 8 to achieve an electrical connection between the front and back sides. The other structures are the same as in Embodiment 1.

[0049] The through electrode 1201 is formed by selectively depositing materials such as nickel or copper onto a portion of the second through hole 8 using photolithography. The first electrode layer 5 will generate parasitic resistance due to the spacing of the through electrodes 1201, but the power loss caused by this parasitic resistance can be reduced to, for example, less than 1%.

[0050] The second through-hole 8, with its through electrode 1201, can block the gas flow path, thus causing a loss in power generation area. This area loss can be suppressed by reducing the through electrode 1201; however, reducing the through electrode 1201 increases the distance electrons need to travel in the XY directions of the first electrode layer 5, leading to increased power loss, which is undesirable. In this case, the increase in power loss can be suppressed, for example, by increasing the thickness of the first electrode layer 5.

[0051] <Implementation Method 8> Figure 13 is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 8 of the present invention. In this embodiment, the material of the first electrode layer 5 is a material that simultaneously possesses electronic conductivity and ion conductivity. In this way, ionized gas can move in the XY direction within the first electrode layer 5. For example, silver possesses both electronic conductivity and oxygen ion conductivity; by using silver to construct the first electrode layer 5, ionized oxygen can move in the XY direction. If the electrolyte layer 6 is a hydrogen ion conductor, and the first electrode layer 5 is made of a material that simultaneously possesses electronic conductivity and ion conductivity, then the ionized gas can also move in the XY direction. Other structures are the same as in Embodiment 1.

[0052] <Implementation Method 9> Figure 14 is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 9 of the present invention. In this embodiment, a surface ion flow path 1401 is provided on the surface of the conductive substrate 2. The other structures are the same as in Embodiment 1.

[0053] As for the material of the surface ion flow path 1401, a material that has both electronic conductivity and ion conductivity is used. In this way, electrons can be supplied to the first electrode layer 5 and oxidant gas can be supplied to each of the second through holes 8. Since the ionized state can move in the solid, the surface ion flow path 1401 does not necessarily need to have gas permeability. Furthermore, the material of the first electrode layer 5 can also be a material that has both electronic conductivity and ion conductivity, as in Embodiment 8.

[0054] <Implementation Method 10> Figure 15 is a cross-sectional view showing a construction example of the fuel cell 1 according to Embodiment 10 of the present invention. In this embodiment, the sealing material 1501 is provided along the outer periphery of the unit cell 3. The other structures are the same as in Embodiment 1.

[0055] In Embodiment 1, no sealing material 1501 is provided. Therefore, to prevent gas leakage, i.e., to prevent the mixing of fuel gas and oxidant gas, the first electrode layer 5 of the porous structure is not provided on the outer periphery of the unit cell 3. Instead, the electrolyte layer 6 is only provided on the porous support layer 4 on the outer periphery. In contrast, this embodiment uses the sealing material 1501 to prevent gas leakage on the outer periphery of the unit cell 3, so the first electrode layer 5 can be provided throughout. As a result, the film thickness of the electrolyte layer 6 can be reduced to a lower value than in Embodiment 1. In Embodiment 1, the electrolyte layer 6 is provided on the porous support layer 4 to prevent gas leakage on the outer periphery, so the film thickness must be sufficient to block the second through hole 8 of the porous support layer 4. In this embodiment, the second through hole 8 can also be blocked on the outer periphery by the first electrode layer 5, as long as the surface voids caused by the porous structure of the first electrode layer 5 are blocked. The voids created by the porous structure of the first electrode layer 5 can be controlled by film formation techniques, for example, by being less than 1 / 10 of the second through-hole 8. Therefore, compared to Embodiment 1, where the electrolyte layer 6 must be formed on the second through-hole 8, the film thickness can be thinner.

[0056] <Implementation Method 11> Figure 16 is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 11 of the present invention. In this embodiment, in addition to the surface flow path 10 of the conductive substrate 2, a surface flow path 1601 is also added to the surface of the porous support layer 4. In this way, compared with the case where only the conductive substrate 2 has surface flow paths, the gas can be supplied to the first electrode layer 5 in a state where it diffuses further in the XY direction. The other structures are the same as in Embodiment 1.

[0057] <Implementation Method 12> Figure 17 is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 12 of the present invention. In this embodiment, multiple second electrode layers 7 are arranged in a segment on a single fuel cell 1. In this way, for example, in the event of a manufacturing defect, as long as the current collector 503 is not placed on the defective part during the manufacturing of the battery stack, the defective location can be electrically isolated, and the whole will not be affected by the partial defect.

[0058] <Implementation Method 13> Figure 18 is a cross-sectional view showing a structural example of the fuel cell 1 according to Embodiment 13 of the present invention. In this embodiment, multiple unit cells 3 are arranged on a single conductive substrate 2. In the case of Embodiment 12, if defective locations are to be eliminated, these locations cannot contribute to power generation, resulting in substantial area loss; however, in this embodiment, area loss caused by defects can be avoided by replacing the entire unit cell 3. Generally speaking, the larger the area, the higher the defect rate. Considering the large area of ​​the entire conductive substrate 2, when the defect rate is high during manufacturing, this embodiment can avoid the increased cost caused by discarding defective products. Furthermore, by dividing the unit cells 3, the risk of damage caused by thermal stress can be suppressed compared to the case of a larger area.

[0059] One point to note is that the surface flow paths 10 of the conductive substrate 2 must be avoided between the multiple configured unit cells 3 to prevent gas leakage. Alternatively, as in embodiment 10, a sealing material 1501 can be provided along the outer periphery of each unit cell 3.

[0060] <Regarding variations of the present invention> This invention is not limited to the foregoing embodiments and may include various modifications. For example, the above embodiments are described in detail for the purpose of clearly illustrating the invention, but are not limited to having all the structures described. Furthermore, a portion of the structure of one embodiment may be replaced with a structure of another embodiment; furthermore, a structure of another embodiment may be added to the structure of one embodiment. Moreover, a portion of the structure of each embodiment may be added to, deleted from, or replaced with other structures.

[0061] 1: Fuel Cell 2: Conductive substrate 2a: First gas inlet 2b: First gas outlet 2c: Second gas inlet 2d: Second gas outlet 3: Unit cell 4: Porous support layer 5: First electrode layer 6: Electrolyte layer 7: Second electrode layer 8: Second through hole 9: First through hole 10: Surface flow path 500: Fuel Cell Stack 501: Separator 501a: First gas inlet 501b: First gas outlet 501c: Second gas inlet 501d: Second gas outlet 502: Cellular part pad 502a: First gas inlet 502b: First gas outlet 502c: Second gas inlet 502d: Second gas outlet 503: Current Collector 504: Upper electrode plate 504a: First gas inlet 504b: First gas outlet 504c: Second gas inlet 504d: Second gas outlet 505: Lower gasket 505a: First gas inlet 505b: First gas outlet 505c: Second gas inlet 505d: Second gas inlet 506: Upper gasket 506a: First gas inlet 506b: First gas outlet 506c: Second gas inlet 506d: Second gas inlet 507: Bottom Frame 508: Sky surface frame 509: Pillar 510: Locking component 511: Gas Flow Path 600: Fuel Cell Stack 601: Unit Stack 1000: Fuel Cell 1001: Current collector 1101, 1102: Precious metal layer 1201: Through electrode 1401: Surface ion flow path 1501: Sealing material 1601: Surface flow path

Claims

1. A fuel cell, characterized by comprising: a conductive substrate having a first through hole; a porous support layer disposed on the conductive substrate and having a second through hole; and a fuel cell cell disposed on the porous support layer, the fuel cell cell comprising: a first electrode layer; an electrolyte layer disposed on the first electrode layer; and a second electrode layer disposed on the electrolyte layer, the conductive substrate being configured to contact the porous support layer at a position in the conductive substrate where the first through hole is not formed, the boundary between the conductive substrate and the porous support layer at the aforementioned position having a structure that allows gas to flow in a direction orthogonal to the extending direction of the first through hole.

2. The fuel cell as described in claim 1, wherein, The aforementioned structure is configured such that a plurality of protrusions protruding from the surface of the aforementioned conductive substrate are arranged in a plane orthogonal to the aforementioned extension direction, and the width of the aforementioned protrusions is smaller than the width of the aforementioned second through hole.

3. The fuel cell as described in claim 1, wherein, The aforementioned structure is composed of an aggregate of microparticles.

4. The fuel cell as described in claim 1, wherein, The aforementioned porous support layer is made of aluminum oxide, and at least one second through hole has metal formed inside it.

5. The fuel cell as described in claim 1, wherein, The diameter of the aforementioned second through hole is less than 300 nm.

6. The fuel cell as described in claim 1, wherein, The thickness of the aforementioned electrolyte layer is less than 1 μm.

7. The fuel cell as described in claim 1, wherein, The aforementioned fuel cell further includes a separator that supports the aforementioned conductive substrate. The aforementioned separator has a flow path for supplying gas to the aforementioned conductive substrate. The aforementioned fuel cell further includes a first current collector disposed on the aforementioned second electrode layer. The aforementioned fuel cell further includes a second current collector disposed between the conductive substrate and the aforementioned separator.

8. The fuel cell as described in claim 1, wherein, The aforementioned fuel cell has a precious metal layer at the boundary where the aforementioned structure contacts the aforementioned porous support layer.

9. The fuel cell as described in claim 1, wherein, The aforementioned first electrode layer has both electronic conductivity and ionic conductivity.

10. The fuel cell as described in claim 1, wherein, The aforementioned fuel cell further includes an ion flow path that simultaneously possesses electronic conductivity and ionic conductivity between the aforementioned conductive substrate and the aforementioned porous support layer.

11. The fuel cell as described in claim 1, wherein, The aforementioned fuel cell also has a sealing material that seals the outer periphery of the aforementioned fuel cell cell.

12. The fuel cell as described in claim 1, wherein, The boundary between the aforementioned porous support layer and the aforementioned first electrode layer is structured such that gas can flow in a direction orthogonal to the extension direction of the aforementioned first through hole.

13. The fuel cell as described in claim 1, wherein, The aforementioned second electrode layer of a single fuel cell cell is divided into two or more.

14. The fuel cell as described in claim 1, wherein, On a single conductive substrate, two or more of the aforementioned porous support layer and the aforementioned fuel cell cells are paired and arranged. On the surface of the aforementioned conductive substrate, the aforementioned structure is not formed in the gap between the aforementioned pairs, or the gap is sealed by a sealing material so that gas cannot be discharged from the aforementioned conductive substrate.

15. The fuel cell as described in claim 1, wherein, The aforementioned structure has a depth of 1 μm or more in the aforementioned extension direction, and the thermal expansion coefficient of the aforementioned conductive substrate is 10 × 10⁻⁶ / K or less.

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