JP5460650B2 - Solid oxide fuel cell - Google Patents

Description

  The present invention relates to a fuel cell having a solid electrolyte, and more particularly to a solid oxide fuel cell.

  A fuel cell includes an anode (fuel electrode) and a cathode (air electrode) with an electrolyte sandwiched between them. Fuel gas is supplied to the anode side, oxidant gas is supplied to the cathode side, and fuel and oxidant are supplied via the electrolyte. It is a power generator that generates electricity by electrochemical reaction. A solid oxide fuel cell (SOFC), which is one of the types of fuel cells, has high power generation efficiency and is operated at a high temperature of 600 to 1000 ° C., so that a fuel reforming reaction can be performed in the cell. is there. For this reason, diversification of fuel can be achieved, the battery system structure can be simplified, and there is a potential for cost reduction compared to other fuel cells. Moreover, it has a feature that it can easily form a hybrid system with other systems such as a combined heat / electric system and a gas turbine by utilizing high-temperature exhaust heat.

  Fuel cells are roughly divided into cylindrical and flat plate shapes depending on the shape of the solid electrolyte, but the cylindrical shape is more resistant to thermal stress than the flat plate type, which is a great advantage for solid oxide fuel cells operating at high temperatures. .

  High power generation efficiency is required to apply and commercialize solid oxide fuel cells in a combined heat / electric system and gas turbine hybrid system. To achieve high power generation efficiency, uniform fuel gas is required. It is necessary to realize a high fuel utilization rate of about 90%.

  As a technique for increasing the utilization rate of a reaction gas in a fuel cell, a technique for supplying a fuel gas uniformly to an electrode by providing a structure in a gas flow path has been proposed. For example, a technique for realizing a high fuel utilization rate by providing a distribution groove in a gas flow path, changing a laminar flow of a flat groove into a turbulent flow, and causing an increase in a mass transfer coefficient of the gas to the rear of the flow path (Patent Document 1) See).

JP-T-2004-509438

  Since the fuel cell has a small electromotive force of about 1.0 V, a plurality of fuel cells are connected in series in many cases. Considering the strength against thermal stress and the gas sealing property, a cylindrical fuel cell In many cases, flat fuel cells need only be stacked, whereas cylindrical fuel cells need to be stacked via connection parts called interconnectors that connect the cells. Yes. As shown in FIG. 16, when adjacent fuel cells are connected by an interconnector, the interconnector connects the outer electrode on the outer surface of the solid electrolyte of the fuel cell and the inner electrode of the adjacent fuel cell. In the region where the connector is connected, the outer electrode on the outer surface of the solid electrolyte is not stretched, and no power is generated in this region. As a result, the fuel gas and the oxidant gas are not consumed, and a concentration gradient is generated, resulting in a result that the gas does not uniformly reach the electrodes. As a result, concentration overvoltage due to gas consumption spots occurs, leading to a decrease in gas utilization rate and power generation efficiency.

  In the prior art, the gas concentration gradient caused by the interconnector connection region is not taken into consideration.

  An object of the present invention is to improve a fuel utilization rate in a solid oxide fuel cell having a cell structure in which an inner electrode is formed inside a closed space formed of a solid electrolyte like a cylindrical fuel cell, The purpose is to increase power generation efficiency.

  The solid oxide fuel cell of the present invention is provided with an inner electrode provided in a closed space formed of a solid electrolyte, an outer electrode provided on an outer surface of the solid electrolyte, and an inner side of the inner electrode. A gas flow path and a cell having an interconnector electrically connected to the inner electrode, and having a flow control unit at a position facing the interconnector across the inner electrode, the flow control unit being The gas permeability is smaller than that of the gas flow path.

  According to the present invention, the fuel utilization rate of the solid oxide fuel cell can be improved and the power generation efficiency can be increased.

The cross-sectional schematic diagram explaining the solid oxide fuel cell which showed embodiment regarding this invention. The figure explaining a flat cylindrical fuel cell and an interconnector. The figure explaining the shape model which applied this invention to the flat cylindrical fuel cell. The figure explaining the effect of this invention from a simulation analysis result. The figure explaining the effect of this invention from a simulation analysis result. The figure explaining a flat cylindrical fuel cell and an interconnector. The figure explaining the case where this invention is applied to arrangement | positioning of an interconnector. The figure explaining the case where this invention is applied to arrangement | positioning of an interconnector. The figure explaining fuel concentration distribution from a simulation analysis result. The figure explaining the shape of the flow control member of the present invention. The figure explaining the relationship between the arrangement position of a flow control member and porosity. The figure explaining arrangement | positioning of the interconnector in a flat cylindrical fuel cell. The figure explaining arrangement | positioning of the interconnector in a flat cylindrical fuel cell. The figure explaining the relationship between the arrangement position of a flow control member and the connection area ratio of the interconnector and inner electrode which occupies for the inner electrode area. The figure explaining the relationship between the arrangement position of a flow control member and the connection area ratio of the interconnector and inner electrode which occupies for the inner electrode area. The cross-sectional schematic diagram explaining a fuel cell cell lamination | stacking by the connection of an interconnector.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a solid oxide fuel cell showing a first embodiment relating to the present invention.

  The present invention is directed to a cell having a shape forming a closed space, such as a cylindrical shape, a flat cylindrical shape, an elliptical shape, a rectangular parallelepiped shape, or a cubic shape, instead of a flat plate shape. That is, a cell having a structure in which electrodes are formed on the inside and outside of a cylindrical solid electrolyte cylinder is an object. The anode and the cathode may be provided either inside or outside the closed space formed by the solid electrolyte, but in the following embodiment, a case where the anode is provided inside and the cathode is provided outside will be described.

  In FIG. 1, a fuel cell 100 has a cathode electrode 105 on the outer surface of a solid electrolyte 104, and an anode electrode 103 inside a closed space surrounded by the solid electrolyte. An interconnector 101 that is electrically connected to take out the current of the anode electrode 103 to the outside is provided. A gas flow path 102 is provided inside the anode electrode 103. On the gas channel side of the anode electrode 103, a porous member 106 having a gas permeability smaller than that of the gas channel is provided. The installation location of the porous member 106 is set so as to face the interconnector 101 with the anode electrode 103 interposed therebetween. The fuel gas flows through the gas flow path 102, and the oxidant gas flows along the cathode electrode 105 on the outer peripheral side of the fuel cell 100. Here, in the anode electrode 103 in the region connected to the interconnector 101, the power generation reaction does not occur because the solid electrolyte and the cathode electrode necessary for the power generation action do not exist. Therefore, the fuel supplied to the anode electrode 103 in the vicinity of the interconnector 101 is not consumed, so that fuel gas consumption spots occur in the surface of the anode electrode 103. This consumption spot causes a decrease in power generation efficiency. The present invention is characterized in that a porous member 106 having a gas permeability smaller than that of the gas flow path is provided at a position facing the interconnector 101 with the anode electrode 103 interposed therebetween. The porous member 106 reduces the supply of fuel gas to the vicinity of the anode electrode 103 in the region connected to the interconnector 101, and accordingly, the flow rate to the other region of the anode electrode 103 where the fuel is consumed increases. Fuel gas consumption spots in the surface of the anode electrode 103 are reduced. Thereby, the concentration overvoltage due to consumption spots is reduced, and the gas utilization rate and power generation efficiency can be increased.

  The solid electrolyte 104 is a cylindrical cell bag tube, and, for example, yttrium-stabilized zirconia (YSZ) can be used as the material. As other constituent members, it is desirable to use, for example, a porous cermet made of nickel and YSZ for the anode electrode 103, lanthanum manganate for the cathode electrode 105, and lanthanum chromide for the interconnector 101.

  The gas flow path 102 may be hollow or a porous material may be used to improve the improvement of gas diffusivity, and the porous material is preferably a porous body containing nickel. This is because a porous cermet made of nickel and YSZ is often used for the anode electrode material, and the gas flow path 102 is in contact with the anode electrode 103, so that the porous material of the gas flow path 102 contains nickel. This is because the use of materials makes it easy to join the two. Nickel has a low electric resistance and also functions as a reforming catalyst, so that it is preferable as a material for the gas flow path 102 from this point. The porous member 106 is disposed in the gas flow path region in the vicinity of the anode electrode 103 in the region connected to the interconnector 101 where fuel is not consumed, and the gas flow rate is set so that the fuel gas is distributed to other regions where the gas is consumed. It is something to control. Since the porous member 106 is joined to the anode electrode 103, a porous body containing nickel is preferable. When a porous material is used for the gas flow path 102, the porosity of the porous material constituting the gas flow path 102 is desirably 90% or more, and the porosity of the porous member 106 is desirably less than 50%. Thus, by providing a relative disparity in the porosity, the ease of gas flow is changed, and the gas flow in the gas flow path region near the anode electrode 103 in the region connected to the interconnector 101 is suppressed. As a result, a large amount of gas is supplied to the region where the fuel is consumed, so that concentration overvoltage due to consumption spots is reduced, and the gas utilization rate and power generation efficiency can be increased. Further, the porous member 106 may be a structural member containing nickel having no pores. In addition, the porous porosity said here refers to the volume ratio of the pore comprised by a communicating hole, and does not include the obstruct | occluded pore which a gas does not flow.

  Next, the effect of the present invention will be described by analysis using numerical simulation. Verification of the effect of the present invention by simulation analysis was performed using a flat cylindrical fuel cell. 2 and 3 are conceptual diagrams of flat cylindrical fuel cells. In FIG. 2, the flat cylindrical fuel cell 200 is configured such that the inner electrode is an anode electrode, the outer electrode is a cathode electrode, and the fuel gas passes through a space closed by the inner electrode. The flat cylindrical fuel cell 200 is provided with six interconnectors 220 which are electrical connection elements for taking out the current of the anode electrode, so that the current path with the anode electrode is shortened and the electrical resistance is reduced. It has been devised. A cross-sectional view of the flat cylindrical fuel cell 200 taken along the line AA is shown in FIG. In FIG. 3, the flat cylindrical fuel cell 200 has a cathode electrode 306 on the outer surface of the solid electrolyte 305, and an anode electrode 304 inside a closed space surrounded by the solid electrolyte 305. Interconnectors 321, 322, and 323 are electrically connected to the anode electrode 304 in order to extract the current of the anode electrode 304 to the outside. Inside the anode electrode 304 is a gas flow path 302. Porous members 311, 312, and 313 are installed in the gas flow path 302 so as to cover the vicinity of the anode electrode 304 in a region connected to the interconnectors 321, 322, and 323. The fuel gas flows through the gas flow path 302, and the oxidant gas flows along the outer peripheral surface of the cathode electrode 306.

  The shape model of the flat cylindrical fuel cell used in the simulation will be described. The basic configuration is the same as the structure shown in FIG. The anode electrode had a flat cylindrical shape with a width of 36 mm, a height of 2 mm, and a length of 200 mm, and a thickness of 10 μm. A gas flow path having the same shape as the inner electrode is formed inside the anode electrode. The gas flows from the inlet 411 shown in FIG. The solid electrolyte and the cathode electrode were formed outside the anode electrode, the axial length was 170 mm, the thickness of the solid electrolyte was 5 μm, and the thickness of the cathode electrode was 10 μm. The solid electrolyte and the cathode electrode are provided with six windows each having a width of 4 mm and a length of 60 mm for installation of the interconnector. The interconnector is connected to the anode electrode through the window. Six interconnectors were installed, and the dimensions were 3 mm in width, 58 mm in length, and 15 μm in thickness. As shown in FIG. 3, the shape model of the flat cylindrical fuel cell used in the simulation has a width of 3 mm, a length of 58 mm, and a thickness of 500 μm so as to cover the vicinity of the anode electrode in the region connected to the interconnector. Six porous members were installed.

Next, the material and physical property values of each element will be described. In this simulation, a Ni foam porous material having a density of 8900 Kg / m ³ , a specific heat of 460.6 J / KgK, a thermal conductivity of 91.74 W / mK, a porosity of 0.95, and a thickness of 2 mm is used in the simulation. , The anode electrode has a density of 7430 Kg / m ³ , a specific heat of 456 J / KgK, a thermal conductivity of 11 W / mK, a porosity of 0.3 + Ni + SCSZ material, the solid electrolyte has an SCSZ material, and the cathode electrode has a It was assumed that a (La, Sr) MnO ₃ material having a density of 4500 Kg / m ³ , a specific heat of 566 J / KgK, a thermal conductivity of 2.2 W / mK, and a porosity of 0.3 was used. The interconnector is made of (La, Ca) CrO ₃ material having a density of 6300 Kg / m ³ , specific heat of 500 J / KgK, and thermal conductivity of 2 W / mK, and the porous member is made of the same material as the gas flow path and has a thickness of 0 It was assumed that a Ni foam porous material having a porosity of 0.3 mm of 0.3 mm was used. This shape model is CASE_B, and for comparison, a shape model in which the porosity of the porous member is set to 0.95, which is the same as the porous member used in the gas flow path, is created as CASE_A. Verified. In the simulation, a general-purpose thermal fluid analysis simulator Fluent of ANSYS was used, an SOFC submodule was incorporated to simulate an electrochemical reaction, and a fuel gas concentration distribution in the gas flow path was analyzed.

In the analysis by simulation, pure hydrogen was used as the fuel gas flowing through the gas flow path inside the anode electrode, and air was used as the oxidant gas flowing along the outer peripheral side of the cathode electrode. The operating conditions of the fuel cell were such that the gas flow rate was set so that the fuel utilization rate was 90% and the oxygen utilization rate was 20%, and the fuel gas and air inlet gas temperatures were 800 ° C. Assuming that the fuel cell is covered with a heat insulating material, the heat flow rate from the fuel cell is set to zero W / cm ² .

The simulation analysis results will be described. Evaluation was made based on the hydrogen concentration distribution (molar fraction) in the fuel gas of the gas flow at a current density of 0.4 A / cm ² . As a result, it was found that CASE_B has a higher hydrogen concentration in the vicinity of the anode electrode in the region connected to the interconnector than CASE_A, and the region becomes larger. FIG. 4 shows the tendency of the concentration distribution (molar fraction) of hydrogen H ₂ in the AA cross section of FIG. In FIG. 4, in CASE_A, the hydrogen concentration in the region of the gas flow path 302 in the vicinity of the porous member, that is, the anode electrode 304 connected to the interconnector is high, and the region extends over a wide range. Therefore, fuel is not consumed in this region, and there is a concern of causing a performance deterioration due to consumption spots. On the other hand, in CASE_B using a porosity of 0.3 for the porous member, there is a portion where the hydrogen concentration is high in the gas flow channel region near the anode electrode connected to the porous member, that is, the interconnector. Is significantly smaller than CASE_A, and it can be seen that the concentration difference from other gas flow path regions is eliminated. FIG. 5 shows the result of the analysis with specific numerical values.

  In FIG. 5, in the analysis result of CASE_A using the same porosity of 0.95 as the gas channel for the porous member, the molar fraction indicating the hydrogen concentration in the gas channel is 10.04. The molar fraction of hydrogen in the gas flow path region in the vicinity of the anode electrode connected to the interconnector is as high as 11.36, and it can be seen that the fuel is not consumed around the porous member, the fuel is concentrated and there are consumption spots.

  On the other hand, in the analysis result of CASE_B using a porosity of 0.3 for the porous member, the molar fraction indicating the concentration of hydrogen fuel in the gas flow path is 10.21, 1.7% compared to the case of CASE_A. The molar fraction of hydrogen in the gas flow path region in the vicinity of the anode electrode connected to the porous member, ie, the interconnector, is 10.64, a value close to that of the gas flow path, It can be seen that consumption spots have been eliminated.

  Thus, the inner electrode provided inside the closed space formed of the solid electrolyte, the outer electrode provided on the outer surface of the solid electrolyte, the gas flow path provided on the inner side of the inner electrode, the inner electrode, In a solid oxide fuel cell including a cell having an electrically connected interconnector, a flow rate control unit having a gas permeability smaller than that of the gas flow path is provided at a position facing the interconnector with the inner electrode interposed therebetween. Thus, the flow of gas near the inner electrode part connected to the interconnector part is suppressed, and the gas flow rate supplied to the area where the fuel gas or oxidant gas is consumed increases, so the concentration overvoltage due to consumption spots is reduced, Gas utilization and power generation efficiency can be increased.

  Next, the distribution of current density in the solid electrolyte 305 was evaluated by the simulation analysis described above. The current density was highest near the inlet 1601 of the gas flow path, and gradually decreased toward the outlet of the gas flow. As a result, the amount of power generation decreased from the inlet toward the outlet. That is, it is shown that a large amount of fuel gas and oxidant gas is consumed near the inlet 1601 and gradually decreases toward the outlet. Then, the conceptual diagram of the fuel cell which showed the means to solve the fuel consumption spot upstream and downstream of a gas flow path next is shown in FIG. In FIG. 6, the porosity of the flow control member 810 on the gas flow path inlet 801 side is increased with respect to the flow control members 810 and 820 arranged in the gas flow path region near the inner electrode portion connected to the interconnector. The porosity of the flow control member 820 on the side away from the gas flow path inlet 801 is set to be low.

  For example, the relationship between the distance from the inlet and the porosity of the flow control member is set as shown in FIG. 11, and gas flows in the upstream flow control member 810, and no power is generated in this region. The agent gas is not consumed, and the gas can flow to the downstream area as much as it flows. Further, as it goes downstream, it becomes difficult for gas to flow to a region where power generation is not performed, and a large amount of fuel or oxidant gas flows in the power generation region in the downstream portion, so that consumption of fuel or oxidant gas is increased. In this way, by setting the porosity of the flow control member shown in FIG. 11 so that the consumption of fuel or oxidant gas is uniform from upstream to downstream, the consumption of fuel or oxidant gas is reduced as it goes downstream. The problem of decreasing can be improved, and the gas utilization rate and power generation efficiency can be improved.

  In the fuel cell 900 of FIG. 7, an interconnector that electrically connects adjacent fuel cells is composed of a plurality of interconnector members 910, 920, and 930, which are staggered with respect to the flow direction 901 of the gas flow path. By arranging, the region where the gas is not consumed is dispersed in the vicinity of the inner electrode portion connected to the interconnector portion, and the concentration overvoltage due to the consumption spot can be reduced. As a result, the gas utilization rate and power generation efficiency can be increased. Further, in the fuel cell 1000 shown in FIG. 8, an interconnector that electrically connects adjacent fuel cells is formed of an elliptical or polygonal interconnector member 1010 including a circle, and the flow direction of the gas flow path 1001 is arranged in a staggered manner or irregularly, so that the area where the gas is not consumed is dispersed in the vicinity of the inner electrode portion connected to the interconnector portion, and the concentration overvoltage due to consumption spots is reduced, thereby reducing the gas utilization rate. It also increases power generation efficiency.

  A fuel cell 1400 in FIG. 12 is an example in which an interconnector that electrically connects adjacent fuel cells is divided into a plurality of blocks. A plurality of interconnector members are constituted by three blocks 1510, 1520, and 1530, and the interconnector members are gathered at the center of the flow path with the fastest gas flow rate in the flow direction 1401 of the gas flow path in each block. Arranged. With this configuration, in the vicinity of the inner electrode portion connected to the interconnector portion, the region where the gas is not consumed is uniformly dispersed, and the concentration overvoltage due to consumption spots can be reduced. As a result, the gas utilization rate and power generation efficiency can be increased. In addition, a fuel cell 1500 shown in FIG. 13 is configured such that interconnectors 1510 that electrically connect adjacent fuel cells are formed in a plurality of elliptical shapes and are randomly dispersed. The shape of the interconnector may be an ellipse including a circle, or a polygon such as a rectangle, a square, a triangle, or a rhombus. Further, as shown in FIGS. 12 and 13, the interconnector members are arranged so that the proportion of the interconnector in the flow path decreases with respect to the flow directions 1401 and 1501 from the upstream to the downstream. As a result, since the area where the interconnector and the inner electrode are in contact with each other is gradually reduced, the region where power can be generated increases as it goes downstream, and fuel or oxidant gas is gradually consumed upstream of the gas flow path. As a result, it is possible to improve the problem that a large amount of fuel or oxidant gas is consumed upstream of the gas flow path and less downstream, and the fuel or oxidant gas consumption can be made uniform.

  14 and 15 show changes in the ratio of the area where the interconnector and the inner electrode occupy in the area of the inner electrode from the inlet to the outlet of the flow path. FIG. 14 shows the connection area ratio between the interconnector and the inner electrode in the inner electrode area of the fuel cell 1400 shown in FIG. In FIG. 14, the interconnector occupies the inner electrode area of the interconnector arrangement block 1410 close to the entrance, and the interconnector ratio occupying the inner electrode area of the interconnector arrangement block 1420 at the center is 0.5. The inner electrode connection area ratio 1702 is 0.3, and the interconnector and inner electrode connection area ratio 1703 occupying the inner electrode area of the interconnector arrangement block 1430 close to the outlet is 0.1. In this way, by decreasing the connection area ratio between the interconnector and the inner electrode that occupies the inner electrode area as it goes downstream, the power generating region can be allocated less in the upstream and more in the downstream. As a result, the problem of excessive consumption upstream and less consumption downstream can be solved, and fuel or oxidant gas consumption can be made uniform upstream and downstream. In addition, by setting the connection area ratio between the interconnector and the inner electrode in the inner electrode area for each interconnector arrangement block, it becomes easy to make the gas consumption uniform from upstream to downstream.

  FIG. 15 shows a connection area ratio between the interconnector and the inner electrode in the inner electrode area of the fuel cell 1500 shown in FIG. In FIG. 15, the connection area ratio between the interconnector and the inner electrode that continuously occupies the inner electrode area from the inlet to the outlet decreases, and the connection area ratio between the interconnector and the inner electrode that occupies the inner electrode area as it goes downstream. Is set to be smaller. In this way, since the region where power can be generated is small in the upstream and many can be allocated in the downstream, the problem of excessive consumption in the upstream and less consumption in the downstream can be solved, and the fuel or oxidant Gas consumption can be made uniform upstream and downstream.

  FIG. 9 shows an enlarged view 901 of a region 1103 having a high hydrogen concentration in the hydrogen fuel concentration distribution (molar fraction) of CASE_A shown in FIG. In the enlarged view 901, when the shape of the region where the hydrogen concentration is particularly high is seen, it has a semi-elliptical shape like 1102. In order to eliminate fuel consumption spots, a flow rate control member with a low gas permeability is arranged in the vicinity of the inner electrode part connected to the interconnector part, but when the volume of the flow rate control member increases, the gas flow in the entire gas flow path It worsens and pressure loss increases. Therefore, in order to reduce the volume of the flow rate control member as much as possible, it is preferable that the flow rate control member be shaped to match the non-fuel consumption region.

  Therefore, the shape of the flow rate control member 1203 having a small gas permeability disposed near the inner electrode portion connected to the interconnector portion 1202 is similar to a shape such as 1210 having a semi-elliptical cross section as shown in FIG. It is desirable to have a shape such as 1220 where is a triangle. On the other hand, as described with reference to FIG. 8, when the shape of the interconnector that electrically connects adjacent fuel cells is an ellipse including a circle or a polygon, the inner side connected to the interconnector portion 1202 The shape of the flow rate control member 1203 having a small gas permeability arranged near the electrode portion is a semispherical shape such as 1230 having a semi-elliptical cross section, or a triangular pyramid such as 1240 having a triangular cross section. The shape is desirable. Further, it is preferable that the flow control member is streamlined so that vortices are not generated before and after the flow control unit so that a vortex is generated downstream of the flow control member 1203 and no malfunction occurs. .

  In the above embodiment, the case where the anode is provided inside and the cathode is provided outside has been described, but the same effect can be obtained even when the cathode is provided inside and the anode is provided outside.

Claims (5)

An inner electrode provided in a closed space formed of a solid electrolyte; an outer electrode provided on an outer surface of the solid electrolyte; a gas flow path provided on the inner side of the inner electrode; In a solid oxide fuel cell comprising cells having interconnected interconnectors,
Having a flow rate controller at a position facing the interconnector across the inner electrode;
The flow control unit is minor gas permeability than the gas flow path,
The gas flow path and the flow rate control unit is constructed of a porous material, a is small Ikoto towards the porosity of the porous material constituting the flow control unit than the porosity of the porous material constituting the gas passage A solid oxide fuel cell.   The flow control unit according to claim 1, wherein the flow rate control unit is formed of a porous member having a porosity of less than 50%, and a cross-sectional shape having a semi-elliptical shape including a circle or a polygon such as a rectangle, a square, a triangle, a rhombus, or A solid oxide fuel cell having a hemispherical shape or a triangular pyramid shape.   2. The solid oxide fuel cell according to claim 1, wherein the porosity of the flow rate control unit gradually decreases from the inlet to the outlet of the gas flow path. 2. The solid according to claim 1 , wherein the porosity of the porous material constituting the gas flow path is 90% or more, and the porosity of the porous material constituting the flow rate control unit is less than 50%. Oxide fuel cell. An inner electrode provided in a closed space formed of a solid electrolyte; an outer electrode provided on an outer surface of the solid electrolyte; a gas flow path provided on the inner side of the inner electrode; In a solid oxide fuel cell comprising cells having interconnected interconnectors,
Having a flow rate controller at a position facing the interconnector across the inner electrode;
The flow rate control unit has a gas permeability smaller than that of the gas flow path,
The interconnector is divided into a plurality of parts, and the interconnector and the flow rate control unit are staggered or randomly arranged along the gas flow path.