A planar solid oxide fuel cell stack

Abstract

This application relates to the field of solid oxide fuel cell stack technology, and proposes a planar solid oxide fuel cell stack, including a stack body and a cavity assembly. The stack body is composed of multiple repeating cell units stacked together, each unit containing a single cell and metal connectors on both sides. The metal connectors have inlets and outlets for the anode and cathode, forming a cross-flow configuration, and internally forming corresponding anode fuel channels and cathode air channels. Four airflow cavities are located around the stack, connecting to the four inlets and outlets respectively. At least one of the inlets and outlets is a constriction; at least one of the anode fuel channel and cathode air channel is a branch flow channel, which includes a main air inlet channel, a main air outlet channel, and multiple branch flow microchannels connecting the two. The branch flow microchannels are surrounded by an array of ribs, with the number of ribs increasing and then decreasing along the airflow direction, and the rib length decreasing and then increasing, forming a gradual flow resistance. The constriction design and the branch flow channels work together to improve the compactness and sealing reliability of the stack structure while ensuring the uniformity of the flow field.

Description

Technical Field

[0001] This application relates to the field of solid oxide fuel cell stack technology, and more particularly to a planar solid oxide fuel cell stack. Background Technology

[0002] Solid oxide fuel cells (SOFCs) are all-solid-state energy conversion devices that efficiently convert the chemical energy of fuel directly into electrical energy through electrochemical reactions. They offer advantages such as high energy conversion efficiency, wide fuel adaptability, and low emissions. Flat-plate SOFC stacks, due to their compact structure and high power density, have become a key area of ​​research and commercial application.

[0003] In the structural design of planar SOFC stacks, sealing reliability under long-term operation is one of the core challenges. Currently, most common external flow channel stacks adopt cross-flow or counter-flow gas flow configurations. To ensure a relatively uniform initial distribution of reactant gases upon entering the electrode active area, the inlet and outlet ports are typically designed to be large. This large inlet and outlet structure necessitates the installation of large-area gas distribution chambers on the sides of the stack for connection and gas distribution. This directly leads to two prominent problems: first, it significantly increases the overall volume and unused space of the stack, resulting in a decrease in its volumetric power density; second, the sealing path around these large chambers (i.e., the high-temperature sealing line) is significantly lengthened. In the operating environment of SOFCs (typically operating at 600-850℃), excessively long sealing lines pose a greater risk of failure due to differences in the thermal expansion coefficients of the component materials and long-term high-temperature creep, severely limiting the stack's service life and reliability.

[0004] To address these challenges, existing technologies have several solutions aimed at optimizing fuel cell stack structure. For example, these include integrating inlet and outlet functions into fewer gas flow chambers, or altering and lengthening gas paths through complex internal flow channels. These improvements simplify the external structure or optimize internal airflow organization to some extent. However, these solutions typically do not address the root of the problem—the size of the inlet and outlet ports on a single cell. Since the openings directly communicating with the electrode active areas remain relatively large, there is still considerable room for optimization in the matching gas flow chambers and their corresponding sealing perimeter. Furthermore, highly integrated structures may increase manufacturing complexity and cost.

[0005] In summary, despite various structural optimization attempts, the field still faces a prominent and unresolved technical contradiction and challenge: in planar SOFC stacks, there is an inherent contradiction between shortening the sealing line length and reducing the stack volume to improve sealing reliability and volumetric power density, and ensuring the uniform distribution of reactant gases throughout the broad electrode active region to guarantee electrochemical performance. Existing technical solutions often struggle to significantly improve structural compactness while ensuring that flow field uniformity remains intact. Application content

[0006] In view of this, this application proposes a planar solid oxide fuel cell stack, which aims to solve the technical problem in the prior art of how to simultaneously shorten the sealing line length of the planar solid oxide fuel cell stack, reduce its volume, and ensure the uniform distribution of reactant gas in the electrode active area.

[0007] The technical solution of this application is implemented as follows: This application provides a planar solid oxide fuel cell stack, comprising: The fuel cell stack body includes multiple battery repeating units stacked along the stacking direction. Each battery repeating unit includes a single cell and metal connectors disposed on both sides of the single cell. The metal connectors are provided with an anode fuel inlet, an anode fuel outlet, a cathode air inlet, and a cathode air outlet, and the anode fuel inlet and outlet and the cathode air inlet and outlet form a crossflow configuration. The metal connectors are provided with anode fuel channels and cathode air channels on both sides along the thickness direction. The anode fuel channels are connected to the anode fuel inlet and the anode fuel outlet, respectively, and the cathode air channels are connected to the cathode air inlet and the cathode air outlet, respectively. The chamber assembly includes a first airflow chamber, a second airflow chamber, a third airflow chamber, and a fourth airflow chamber; the four airflow chambers are disposed around the main body of the fuel cell stack perpendicular to the stacking direction, the first airflow chamber is connected to the anode fuel inlet, the second airflow chamber is connected to the anode fuel outlet, the third airflow chamber is connected to the cathode air inlet, and the fourth airflow chamber is connected to the cathode air outlet. At least one of the anode fuel inlet, anode fuel outlet, cathode air inlet, and cathode air outlet has a projected area in the stacking direction that is smaller than the projected area of ​​the corresponding electrode active region in the same direction. At least one of the anode fuel channel and / or cathode air channel is configured as a split flow channel, which includes a main air intake channel, a main air outlet channel, and multiple split microchannels connecting the two. The main air intake channel is connected to the corresponding anode fuel inlet or cathode air inlet, and the main air outlet channel is connected to the corresponding anode fuel outlet or cathode air outlet. The split microchannels are formed by an array of ribs and flow in the direction of gas flow from the inlet side to the middle of the connector and then to the outlet side. The number of each group of ribs in the array first increases and then decreases, and the length of each group of ribs first decreases and then increases.

[0008] Based on the above technical solution, preferably, the anode fuel inlet, anode fuel outlet, cathode air inlet and cathode air outlet are all constricted, and their projected area in the stacking direction is smaller than the projected area of ​​the corresponding electrode active area in the same direction.

[0009] Based on the above technical solution, preferably, the angle between the extension direction of the diversion microchannel in the diversion channel and the length direction of the main air intake channel and the main air outlet channel is 70° to 110°.

[0010] Based on the above technical solution, preferably, the extension direction of the diversion microchannel is perpendicular to the length direction of the main air intake channel and the main air outlet channel.

[0011] Based on the above technical solution, preferably, the cross-sectional area of ​​the main air intake channel and the main air outlet channel is larger than the cross-sectional area of ​​any of the diversion microchannels; the orthographic projection of the main air intake channel on the metal connector completely covers the corresponding cathode air inlet or anode fuel inlet; the orthographic projection of the main air outlet channel on the metal connector completely covers the corresponding cathode air outlet or anode fuel outlet.

[0012] Based on the above technical solution, preferably, the array ribs are arranged in groups, with adjacent groups of array ribs arranged in parallel or approximately parallel, to guide airflow from the main air intake channel into each branch microchannel, and from each branch microchannel to the main air outlet channel.

[0013] Based on the above technical solution, preferably, a first sealing area is provided on one side of the metal connector, which is arranged around the anode fuel channel, and an anode sealing ring is provided in the first sealing area. A second sealing area is provided on the other side of the metal connector, which is arranged around the cathode air channel, and a cathode sealing ring is provided in the second sealing area.

[0014] Based on the above technical solution, preferably, the anode fuel channel and the cathode air channel adopt the same or mirrored split channel topology, and their gas inlet direction and gas outlet direction are set in opposite directions.

[0015] Based on the above technical solution, preferably, the surface of the first airflow chamber shell is recessed to form a fuel intake channel, the fuel intake channel is connected to the anode fuel inlet through a fuel intake hole, and a first sealing ring is provided between the first airflow chamber shell and the stack body to seal the connection between the fuel intake channel and the anode fuel inlet. The surface of the second airflow chamber shell is recessed to form a fuel outlet channel, which is connected to the anode fuel outlet through a fuel outlet hole; a second sealing ring is provided between the second airflow chamber shell and the stack body to seal the connection between the fuel outlet channel and the anode fuel outlet. The surface of the third airflow chamber shell is recessed to form an air intake channel, which is connected to the cathode air inlet through an air intake hole; a third sealing ring is provided between the third airflow chamber shell and the fuel cell body to seal the connection between the air intake channel and the cathode air inlet. The surface of the fourth airflow chamber shell is recessed to form an air outlet channel, which is connected to the cathode air outlet through an air outlet hole; a fourth sealing ring is provided between the fourth airflow chamber shell and the fuel cell body to seal the connection between the air outlet channel and the cathode air outlet.

[0016] Based on the above technical solution, preferably, the fuel cell stack body further includes a top end plate connector, a bottom end plate connector, an upper insulating plate, a lower insulating plate, an upper cover plate, and a base; the top end plate connector and the bottom end plate connector are respectively disposed at the top and bottom of the fuel cell stack body, the upper insulating plate and the lower insulating plate are respectively disposed on the outside of the top end plate connector and the bottom end plate connector, the upper cover plate and the base are respectively located on the outside of the upper insulating plate and the lower insulating plate, and the upper cover plate and the base are fixedly connected by a first fastener, and the first airflow cavity shell and the second airflow cavity shell, as well as the third airflow cavity shell and the fourth airflow cavity shell, are all fixedly connected by a second fastener.

[0017] This application has the following advantages over the prior art: 1) This application's embodiments, by introducing a "reduced-aperture" inlet / outlet design, solve the problems of excessively long sealing lines and excessively large stack volume, achieving the effect of improving sealing reliability and volumetric power density. Meanwhile, the "splitting channel" design with a specific gradient array rib structure precisely addresses the gas distribution uniformity problem inevitably exacerbated by the "reduction." The reduced-aperture design presents a new challenge to uniform gas distribution, while the splitting channel effectively addresses this challenge through its sophisticated flow resistance network reconstruction. Working together, these two technologies achieve a comprehensive technical effect of significantly optimizing the compactness of the planar solid oxide fuel cell stack while ensuring the uniformity of its internal flow field, resolving a pair of long-standing technical contradictions in this field.

[0018] 2) By meticulously designing the dimensional ratio of the main channel and the branching microchannels, and strictly limiting the spatial projection coverage relationship between the main channel and the airflow inlet and outlet, the internal configuration of the branching channel system was optimized from both "size" and "position" dimensions. This enhanced the pressure stabilization and distribution hub function of the main channel, ensuring the precision and efficiency of airflow path connection, enabling the branching channels to operate with higher reliability and efficiency, and further ensuring a stable and uniform gas distribution throughout the entire electrode active area.

[0019] 3) This embodiment clarifies the integrated processing technology of the metal connector. This technology is mature, low-cost, and highly efficient, and can ensure accurate flow channel dimensions and structural strength, making it particularly suitable for large-scale production. Integrated molding avoids interface resistance and sealing problems caused by assembling multiple components, further improving the reliability and performance of the fuel cell stack. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a perspective view of the planar solid oxide fuel cell stack disclosed in the embodiments of this application; Figure 2 This is an exploded view of the planar solid oxide fuel cell stack disclosed in the embodiments of this application; Figure 3 This is an exploded view of the cell repeating unit of the planar solid oxide fuel cell stack disclosed in the embodiments of this application; Figure 4 This is a schematic diagram of the connection body of the planar solid oxide fuel cell stack disclosed in the embodiments of this application; Figure 5 This is a schematic diagram of the fluid domain of the battery repetition unit of the planar solid oxide fuel cell stack disclosed in the embodiments of this application; Figure 6 This is a simulation result of the fluid mass flow rate of the battery repetition unit in the planar solid oxide fuel cell stack disclosed in the embodiments of this application; Figure label: 1. Stack body; 11. Battery repeating unit; 12. Single cell; 13. Metal connector; 131. Anode fuel inlet; 132. Anode fuel outlet; 133. Cathode air inlet; 134. Cathode air outlet; 135. Flow channel; 1351. Main air intake channel; 1352. Main air outlet channel; 1353. Flow microchannel; 14. Anode sealing ring; 15. Cathode sealing ring; 16. Top end plate connector; 17. Bottom end plate connector; G1. Upper insulating plate; G2. Lower insulating plate; 18. Upper cover plate; 19. Base; T1. First fastener; T2. Second fastener; 2. Cavity assembly; 21. First airflow cavity shell; 22. Second airflow cavity shell; 23. Third airflow cavity shell; 24. Fourth airflow cavity shell; 211. Fuel intake passage; 212. Fuel intake port; 25. First sealing ring; 221. Fuel outlet passage; 222. Fuel outlet port; 26. Second sealing ring; 231. Air intake passage; 232. Air intake port; 27. Third sealing ring; 241. Air outlet passage; 242. Air outlet port; 28. Fourth sealing ring. Detailed Implementation

[0022] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0023] like Figure 1 As shown, combined with Figure 2-4 This application discloses a planar solid oxide fuel cell stack, including a stack body 1 and a cavity shell assembly 2.

[0024] The fuel cell stack 1 is composed of multiple battery repeating units 11 stacked along the stacking direction. Each battery repeating unit 11 includes a single cell 12 and metal connectors 13 disposed on both sides of the single cell 12. The metal connectors 13 are machined with an anode fuel inlet 131, an anode fuel outlet 132, a cathode air inlet 133, and a cathode air outlet 134. The line direction connecting the anode fuel inlet 131 and the outlet is spatially intersected with the line direction connecting the cathode air inlet 133 and the outlet, thus forming a crossflow configuration.

[0025] The metal connector 13 forms independent anode fuel channels and cathode air channels on its two sides along its thickness direction. The two ends of the anode fuel channel are connected to the anode fuel inlet 131 and the anode fuel outlet 132, respectively, while the two ends of the cathode air channel are connected to the cathode air inlet 133 and the cathode air outlet 134, respectively. This basic structure defines independent flow paths that isolate fuel and air, and provides the necessary gas transport paths for the electrochemical reaction.

[0026] In this embodiment, the single cell 12 is typically an anode-supported type, and its basic structure includes an anode layer, an electrolyte layer, and a cathode layer, which together constitute a complete electrochemical unit. The anode layer is responsible for catalyzing the oxidation reaction of fuels (such as hydrogen, carbon monoxide, or reformate), the cathode layer is responsible for catalyzing the reduction reaction of oxygen (from air), and the dense electrolyte layer is used to isolate the fuel from air and allow oxygen ion conduction. The single cell 12 itself does not have large gas channel openings directly provided; the gases required for its reaction need to be transported and distributed through a metal connector 13 that is closely attached to it.

[0027] The combination of the single cell 12 and the two metal connectors 13 forms the basis for gas flow and electrochemical reaction. Specifically, the anode fuel channel of one metal connector 13 guides the fuel gas and distributes it evenly to the entire anode surface of the single cell 12; simultaneously, the cathode air channel of the other metal connector 13 guides the air and distributes it evenly to the entire cathode surface of the single cell 12. Since the anode fuel inlet 131 / outlet and the cathode air inlet 133 / outlet are in a cross-flow configuration, the fuel gas flow and the air flow are separated in the normal direction (i.e., the stacking direction) of the plane of the single cell 12, but cross-flow in the planar projection, which helps to form a uniform temperature and reactant concentration field.

[0028] The basic working principle is as follows: Fuel enters from the anode fuel inlet 131, spreads evenly through the branch channel 135 in the anode fuel channel, and diffuses to the porous anode layer. At the interface between the anode layer and the electrolyte, fuel molecules (such as H2) undergo an oxidation reaction, releasing electrons and generating hydrogen ions (or water). The released electrons flow to the cathode through the external circuit, thereby outputting electrical energy. Simultaneously, air enters from the cathode air inlet 133, spreads evenly through the branch channel 135 in the cathode air channel, and diffuses to the porous cathode layer. In the cathode layer, oxygen molecules receive electrons flowing in from the external circuit and are reduced to oxygen ions. These oxygen ions migrate through the dense electrolyte layer to the anode side, reacting with the fuel to generate water (for hydrogen fuel) or carbon dioxide and water (for hydrocarbon fuel). The reaction exhaust gases are discharged from the anode fuel outlet 132 and the cathode air outlet 134, respectively. The metal connector 13 not only performs the function of distributing gases in this process but also acts as a current collector, responsible for collecting the current generated by the anode and cathode and conducting electrons between adjacent single cells 12.

[0029] In order to allow fuel and air to be introduced into the interior of the stack body 1, this embodiment also includes a cavity shell assembly 2.

[0030] The chamber assembly 2 includes four independent airflow chambers: a first airflow chamber 21, a second airflow chamber 22, a third airflow chamber 23, and a fourth airflow chamber 24. These four airflow chambers are arranged on the four sides of the fuel cell stack body 1 perpendicular to the stacking direction. The first airflow chamber 21 is connected to the anode fuel inlet 131 on the metal connector 13 and is responsible for supplying fuel to the fuel cell stack; the second airflow chamber 22 is connected to the anode fuel outlet 132 and is responsible for discharging the fuel exhaust gas after the reaction; the third airflow chamber 23 is connected to the cathode air inlet 133 and is responsible for supplying air or oxygen to the fuel cell stack; and the fourth airflow chamber 24 is connected to the cathode air outlet 134 and is responsible for discharging the air exhaust gas after the reaction. These four chambers together complete the functions of transporting and collecting reaction gases from the outside to the inside of the fuel cell stack, and exhaust gases from the inside to the outside.

[0031] In this embodiment, at least one of the anode fuel inlet 131, anode fuel outlet 132, cathode air inlet 133, and cathode air outlet 134 has a significantly reduced size. Specifically, the projected area of ​​this inlet or outlet in the stacking direction of the fuel cell is smaller than the projected area of ​​the active reaction region of the corresponding electrode (anode or cathode) it serves in the same direction.

[0032] This reduced-aperture design directly leads to structural optimization. Due to the smaller inlet and outlet sizes, the size and coverage area of ​​the airflow chamber shell covering them can be correspondingly reduced. Compared to traditional fuel cell stacks with large airflow chambers, this design significantly shortens the total path length for sealing these chamber shells while maintaining crossflow advantages, thereby significantly reducing the risk of seal failure under high-temperature operating conditions. Simultaneously, the reduction in ineffective space at the chamber shell and stack edges also effectively reduces the overall volume of the fuel cell stack, increasing its volumetric power density.

[0033] To overcome the problem of uneven gas distribution when entering the electrode active area due to the constriction design, this embodiment also has at least one channel in the anode fuel channel and / or cathode air channel constructed with a specific diversion channel 135. The diversion channel 135 consists of a main air inlet channel 1351, a main air outlet channel 1352, and multiple diversion microchannels 1353 connecting the two.

[0034] In this embodiment, the main intake channel 1351 is connected to the corresponding anode fuel inlet 131 or cathode air inlet 133, and the main exhaust channel 1352 is connected to the corresponding anode fuel outlet 132 or cathode air outlet 134. The main intake channel 1351 mainly undertakes the functions of inlet buffering, pressure stabilization and primary distribution, while the main exhaust channel 1352 mainly undertakes the functions of confluence and exhaust. The multiple diversion microchannels 1353 are responsible for guiding the gas from the main intake channel 1351 into the active zone and guiding the exhaust gas after the reaction to the main exhaust channel 1352.

[0035] In this embodiment, the diversion microchannel 1353 is surrounded by an array of ribs. The array of ribs has a certain arrangement rule: along the direction of gas flowing from the inlet side through the middle of the connector and then to the outlet side, the number of each group of ribs first increases and then decreases, while the length of each group of ribs first decreases and then increases.

[0036] Specifically, near the inlet region, the number of ribs is relatively small but their length is relatively long; near the middle region, the number of ribs gradually increases while the length of each rib decreases; near the outlet region, the number of ribs gradually decreases while their length increases, to balance inlet buffering, middle diffusion, and outlet convergence. Two sets of shorter supplementary ribs, half the height of the array ribs, are designed in the middle section near the inlet and outlet regions to control the height of the corresponding microchannels by half, thereby regulating the uniformity of the fluid flow.

[0037] The aforementioned gradient array ribs do not simply change the shape of the flow channel, but rather utilize the coupled changes in the number and length of the ribs to directionally adjust the local resistance in different regions of the flow field. When gas enters through the constriction, it first undergoes a widening and buffering process within the main inlet channel 1351, and then diffuses to various parts of the active area via the diversion microchannels 1353. During diffusion, the higher diversion capacity in the central region helps to reduce excessive concentration near the inlet, while the edge and distal regions receive more stable gas supply. During the exhaust phase, the exhaust gas converges along multiple diversion microchannels 1353 towards the main outlet channel 1352, preventing backflow or stagnation in local areas due to poor exhaust. Thus, this application does not simply rely on increasing the inlet area to improve distribution, but achieves synergy between the constriction design and uniform gas supply through the reconstruction of the internal flow resistance network of the connector. This design effectively overcomes the problem of insufficient gas supply at the far end of the flow field that may be caused by the narrowing, eliminates the flow dead zone, and ensures the uniform distribution of reactant gas throughout the entire electrode active area. This, in turn, promotes a more uniform distribution of current density and temperature field, laying the foundation for improving the performance of the single cell and the overall efficiency of the stack.

[0038] This application's embodiments address the issues of excessively long sealing lines and large stack volume by introducing a "narrowed" inlet / outlet design, thereby improving sealing reliability and volumetric power density. The "splitting channel" design with a specific gradient array rib structure precisely addresses the gas distribution uniformity problem inevitably exacerbated by the "narrowing." The narrowing design presents a new challenge to uniform gas distribution, which the splitting channel 135 effectively addresses through its sophisticated flow resistance network reconstruction. Working together, these two technologies achieve a comprehensive technical effect that significantly optimizes the compactness of the planar solid oxide fuel cell stack while ensuring internal flow field uniformity, resolving a long-standing technical contradiction in the field.

[0039] In some embodiments, the anode fuel inlet 131, anode fuel outlet 132, cathode air inlet 133, and cathode air outlet 134 are all constricted. Here, "constriction" has a specific quantitative definition: the projected area of ​​each outlet or inlet in the stacking direction is smaller than the projected area of ​​the active reaction region of the corresponding electrode (anode or cathode) in the same direction. This means that not only the individual openings, but all four gas channel openings are significantly reduced in size.

[0040] Because the interface dimensions corresponding to the airflow chamber shells on all four sides are reduced, the coverage area required for each individual chamber shell and the circumference of the mating sealing ring are minimized globally. Compared to solutions with only partially narrowed openings, this solution can further significantly shorten the total length of the high-temperature sealing line of the entire fuel cell stack, thereby reducing the risk of seal failure due to thermal stress and material creep to a greater extent. Simultaneously, the synchronous reduction of the chamber shell structure and edge ineffective space on all four sides can more effectively compress the overall external dimensions and ineffective volume of the fuel cell stack, thus significantly improving the volumetric power density of the stack.

[0041] In some embodiments, the angle between the extending direction of the diversion microchannel 1353 in the diversion channel 135 and the length direction of the main air intake channel 1351 and the main air outlet channel 1352 is 70° to 110°.

[0042] This angle range is designed with clear hydrodynamic considerations in mind. When the branching microchannels 1353 branch off from the main inlet channel 1351 at a near-vertical or large angle and converge towards the main outlet channel 1352, the macroscopic direction of airflow can be changed more effectively. After the gas flows out of the main inlet channel 1351, it needs to undergo a significant turn before entering each branching microchannel 1353. This helps to break the inertial mainstream flow that may be generated due to concentrated intake, and promotes more complete diffusion of the gas to both sides of the channel. At the same time, this angle range ensures that the branching microchannels 1353 have sufficient length to cover the width of the electrode active area, so that the gas can be continuously and evenly distributed to various regions of the flow field during the flow from the inlet side to the outlet side, rather than flowing directly to the outlet prematurely.

[0043] As some preferred embodiments, the extension direction of the diversion microchannel 1353 is perpendicular to the length direction of the main air intake channel 1351 and the main air outlet channel 1352.

[0044] Specifically, the vertical arrangement is a symmetrical and efficient geometric configuration. In this configuration, the branching microchannels 1353 and the main channel form a standard "T"-shaped or "comb-like" flow field topology. Gas flowing out of the main inlet channel 1351 can enter each of the perpendicular branching microchannels 1353 with almost no bias and with the same initial conditions, creating the most favorable geometric basis for the uniform distribution of airflow among the parallel channels. The vertical arrangement also ensures that the change in flow direction is most thorough when the airflow turns from the main channel to the microchannels, maximizing the dissipation of the kinetic energy of the concentrated inlet flow and promoting the lateral spread of gas throughout the active region.

[0045] In some embodiments, the present application also defines the size ratio and spatial correspondence of the diversion channel 135 structure. This definition focuses on the synergistic relationship between the main air intake channel 1351, the main air outlet channel 1352 and the diversion microchannel 1353, aiming to more effectively achieve stable airflow delivery, uniform distribution and efficient collection by optimizing the functional division and geometric matching of each level of the channel.

[0046] Specifically, it was determined that the cross-sectional areas of the main inlet channel 1351 and the main outlet channel 1352 should be larger than the cross-sectional area of ​​any of the branch microchannels 1353. This dimensional relationship has certain hydrodynamic significance. The main channel with a larger cross-sectional area has relatively lower flow resistance and can serve as a low-pressure-loss "main channel," effectively buffering, stabilizing, and initially distributing the airflow entering from the constriction. It acts like a reservoir or distribution main, ensuring that the airflow is transported to the downstream branch channels under relatively uniform pressure conditions. Conversely, multiple branch microchannels 1353 with smaller cross-sectional areas form a "distribution network" with higher local resistance. Their function is to further refine the airflow in the autonomous channels and guide it to various corners of the electrode active area. This "large-pipe distribution, small-pipe uniform flow" dimensional design creates a reasonable flow resistance gradient, which is key to achieving the uniform dispersion of airflow.

[0047] This application embodiment also imposes strict requirements on the spatial correspondence between the main channel and the lower air inlet / outlet, namely, the orthographic projection of the main air inlet channel 1351 on the metal connector 13 needs to completely cover the corresponding cathode air inlet 133 or anode fuel inlet 131, and the orthographic projection of the main air outlet channel 1352 also needs to completely cover the corresponding outlet.

[0048] This limitation ensures excellent flow channel docking efficiency and airtightness. Structurally, it means that when gas enters the fuel cell stack from the gas flow chamber shell through the constriction, it will first enter the "sphere of influence" of the main inlet channel 1351 with a larger cross-sectional area without any omissions. This avoids some airflow from directly impacting areas outside the flow channel or the sealing interface due to misalignment, thus eliminating potential leakage or uneven distribution hazards. Functionally, this ensures that all entering working fluids are buffered and regulated by the main channel, providing a unified and controllable starting point for uniform distribution in the subsequent branching microchannels 1353 network. Similarly, on the outlet side, complete coverage ensures that the reacted exhaust gas can smoothly and unobstructedly flow from each branching microchannel 1353 into the main outlet channel 1352 and be efficiently discharged.

[0049] This application adopts the above-described technical solution, and optimizes the internal configuration of the diversion channel system from both "size" and "position" dimensions by precisely designing the size ratio of the main channel and the diversion microchannel 1353 and strictly limiting the spatial projection coverage relationship between the main channel and the airflow inlet and outlet. This strengthens the pressure stabilization and distribution hub function of the main channel, ensures the accuracy and efficiency of airflow path connection, and enables the diversion channel 135 to operate with higher reliability and efficiency, further ensuring a stable and uniform gas distribution throughout the entire electrode active area.

[0050] In some embodiments, the array ribs are arranged in groups, and the array ribs in adjacent groups are in a parallel or nearly parallel spatial relationship. This grouped, parallel arrangement gives the 1353 flow channel network a highly ordered and regular topology.

[0051] These parallel ribs and the flow channels they enclose are not passively existing gaps, but rather active paths that guide gas flow. On the inlet side, they act like a series of parallel guide channels, smoothly diverting the airflow from the autonomous inlet channel 1351 and guiding it to different lateral positions within the electrode active area. In the middle of the flow channel and on the outlet side, they also serve as clear converging paths, orderly guiding the gas flowing through the active area to the main outlet channel 1352. This guiding effect gives the gas movement a clear direction and organization throughout the flow field, effectively preventing random diffusion, mixing, or the formation of local eddies on the wide electrode surface. This ensures that the entire airflow organization process, from "concentrated introduction" to "uniform spreading" and then to "orderly converging," is controlled and efficient.

[0052] In addition, the parallel ribs form flow channels with basically the same width and direction, which helps to ensure that the geometric constraints and flow resistance experienced by the gas when flowing in different split microchannels 1353 are consistent and comparable, laying a structural foundation for uniform flow distribution.

[0053] In some embodiments, a first sealing region is provided on one side of the metal connector 13, surrounding the anode fuel channel. The first sealing region forms a closed annular or frame-shaped boundary surrounding the anode fuel flow channel. Similarly, on the other side of the metal connector 13 facing the cathode of the single cell 12, a second sealing region is symmetrically provided, surrounding the cathode air channel. This geometric relationship of surrounding arrangement physically defines the flow boundaries of the fuel gas and air, strictly confining the reactant gas within the predetermined flow channel space and preventing it from leaking to the surrounding area.

[0054] Furthermore, the first sealing area is provided with an anode sealing ring 14 to completely seal the fuel gas from the anode fuel channel within a predetermined path flowing to the anode electrode, preventing the fuel gas from leaking outward from the interface between the metal connector 13 and the anode of the single cell 12; correspondingly, the second sealing area is provided with a cathode sealing ring 15 to strictly confine the air in the flow path on the cathode side, preventing the air from leaking outward from the interface between the metal connector 13 and the cathode of the single cell 12.

[0055] In this embodiment, both the anode sealing ring 14 and the cathode sealing ring 15 are C-structured. Two anode sealing rings 14 are symmetrically arranged, forming an anode fuel inlet 131 and an anode fuel outlet 132 between the two anode sealing rings 14. Correspondingly, two cathode sealing rings 15 are also symmetrically arranged, forming a cathode air inlet 133 and a cathode air outlet 134 between the two cathode sealing rings 15.

[0056] In some embodiments, the anode fuel passage and the cathode air passage employ the same or mirror-image flow channel topology. This means that the geometry, size ratio, and rib arrangement of the flow channels constituting the anode and cathode sides are topologically identical or mirror-symmetrical. When the same structure is used, the anode and cathode connectors can be machined using identical flow field molds, greatly simplifying the manufacturing process and ensuring performance consistency. When a mirror structure is used, it is an arrangement symmetrical about a central plane, which typically matches the overall symmetrical design of the fuel cell stack. Regardless of whether it is the same or mirror-image, the core is to ensure a high degree of compatibility and consistency in the flow channel resistance distribution and gas distribution characteristics experienced by the fuel and air on their respective electrode sides.

[0057] The gas inlet and outlet directions on the anode and cathode sides must be set in opposite directions. This is an ingenious arrangement of the macroscopic gas flow direction in a cross-flow configuration. Considering the actual structure of the fuel cell stack, if the anode fuel flows in from one side (e.g., the +X direction) and out from the opposite side (-X direction), then the cathode air must flow in from the adjacent side (e.g., the +Y direction) and out from its opposite side (-Y direction), thus achieving a vertical cross-flow direction in a two-dimensional plane. This opposite inlet and outlet direction setting is key to the efficient and symmetrical realization of the cross-flow configuration. It allows the fuel flow and air flow to form a uniform and stable vertical cross-flow within the single cell plane, maximizing the contact and coverage uniformity of the two reactive gas flows in the electrode active area. This facilitates the formation of a gentle and consistent reactant concentration gradient and temperature field, thereby reducing local hot spots or underreaction areas caused by mismatched or asymmetrical flow directions.

[0058] In this embodiment, the metal connector 13 is made of high-temperature resistant conductive ferritic stainless steel or other conductive metal materials suitable for SOFC operating conditions, such as Crofer 22 series materials. The metal connector 13 can be obtained by integral stamping, rolling, or molding of metal sheets. If necessary, subsequent shaping, surface treatment, or anti-oxidation coating processes can be combined to improve dimensional stability and durability. By integrally forming the main air intake channel 1351, the main air outlet channel 1352, the diversion microchannel 1353, and the peripheral sealing pressure-bearing area, the manufacturing process can be simplified, and the consistency of the flow channel geometry parameters of different batches of connectors can be ensured. This avoids the interface resistance and sealing problems caused by the assembly of multiple components, further improving the reliability and performance of the fuel cell stack.

[0059] In some embodiments, the first airflow chamber shell 21 is dedicated to fuel introduction, and its surface is machined to form a recessed fuel intake channel 211, which is physically connected to the anode fuel inlet 131 on the metal connector 13 through a dedicated fuel intake hole 212. Similarly, the second airflow chamber shell 22 is dedicated to fuel exhaust, and its surface fuel outlet channel 221 is connected to the anode fuel outlet 132 through a fuel outlet hole 222. The third and fourth airflow chamber shells 24 are symmetrically responsible for air introduction and exhaust. The surface of the third airflow chamber shell 23 is recessed to form an air intake channel 231, which is connected to the cathode air inlet 133 through an air intake hole 232. The surface of the fourth airflow chamber shell 24 is recessed to form an air outlet channel 241, which is connected to the cathode air outlet 134 through an air outlet hole 242. This "one shell, one function, corresponding orifice" design clearly separates the inlet and outlet flow paths of fuel and air, which is the basis for realizing the crossflow configuration externally.

[0060] At the interface between each airflow chamber shell and the fuel cell stack body 1, a dedicated sealing ring is provided, and the specific sealing object of each sealing ring is precisely indicated. The first sealing ring 25 is used to seal the connection between the fuel inlet channel 211 and the anode fuel inlet 131, the second sealing ring 26 is used to seal the connection between the fuel outlet channel 221 and the anode fuel outlet 132, the third sealing ring 27 is used to seal the connection between the air inlet channel 231 and the cathode air inlet 133, and the fourth sealing ring is used to seal the connection between the air outlet channel 241 and the cathode air outlet 134.

[0061] In some embodiments, the stack body 1 further includes a top end plate connector 16, a bottom end plate connector 17, an upper insulating plate G1, a lower insulating plate G2, an upper cover plate 18, and a base 19.

[0062] These components are stacked in order from the inside out. The top and bottom endplate connectors 17 are respectively located at the top and bottom of the fuel cell stack body 1. They are made of conductive material and not only serve as the end structure of the fuel cell stack, but also collect and lead out current. During assembly, they also help to evenly distribute pressure across the entire fuel cell stack cross-section. On the outside of the endplate connectors, an upper insulating plate G1 and a lower insulating plate G2 are respectively installed. The core function of these two insulating plates is to achieve electrical insulation. They electrically isolate the high-potential endplate connectors from the externally grounded metal cover and base 19, preventing current leakage or short circuits and ensuring operational safety and system reliability. At the outermost layer, the upper cover 18 and base 19 are located outside the upper and lower insulating plates G2, respectively. They constitute the outermost mechanical protective shell and main load-bearing structure of the fuel cell stack.

[0063] In this embodiment, the upper cover plate 18 and the base 19 are fixedly connected by a first fastener T1. This configuration allows a preset clamping force to be applied and maintained axially on the fuel cell stack. This axial clamping force is transmitted to the entire fuel cell stack body 1 through the insulating plate and end plate connector, ensuring tight and stable surface contact between all internal battery repeating units 11 (including single cells 12, metal connectors 13, and various sealing rings). This ensures good electrical conductivity between layers, maintains the sealing performance of high-temperature sealing rings, and prevents components from loosening due to thermal cycling or vibration.

[0064] The first airflow chamber shell 21 and the second airflow chamber shell 22, as well as the third airflow chamber shell 23 and the fourth airflow chamber shell 24, are all fixedly connected by the second fastener T2. This fastening connection mechanism securely fixes the paired airflow chamber shells laterally, ensuring that their docking positions with the sides of the fuel cell stack body 1 are accurate and firm, preventing displacement or loosening under gas pressure or mechanical vibration, thereby ensuring the long-term sealing reliability of the connection interface between the external gas path and the internal flow channel.

[0065] It should be noted that the number of array ribs, their spacing, rib width, and rib height can be optimized based on the active area size of a single cell 12, the target flow resistance voltage drop, and the working gas flow rate. Without deviating from the core distribution principle of "the number of ribs along the gas flow direction first increases and then decreases, and the rib length first decreases and then increases," the array ribs can be arranged at equal intervals, or in localized areas with non-equal intervals to fine-tune the flow resistance. Similarly, the cross-sectional shape (e.g., rectangular, trapezoidal, or arc-shaped) and specific dimensions (e.g., depth and width) of the shunt microchannel 1353 can also be adjusted for different fuel cell configurations and application requirements, providing good design flexibility.

[0066] The working principle and technical effects of this application can be further explained in conjunction with the accompanying drawings. Please refer to... Figure 5 The schematic diagram of the fluid domain of the repeating unit 11 of the single cell 12 shown is as follows: Figure 6 The simulation results of fluid mass flow rate distribution are shown.

[0067] Simulation analysis shows that under the condition of a constricted design, if the traditional connecting rib arrangement is still used, the gas tends to concentrate in the area near the inlet, while obvious low-flow areas, i.e., "dead zones," appear at the far end and edge of the flow field. In contrast, this application constructs a diversion channel 135 on the connecting body, which is composed of a main inlet channel 1351, a diversion microchannel 1353, and a main outlet channel 1352, and introduces the aforementioned gradually changing arrangement of array ribs. This allows the gas entering from the constricted design to be buffered and initially distributed in the main inlet channel 1351, and then finely redistributed through multiple diversion microchannels 1353 with different paths and controlled flow resistance. Figure 6 The simulation results clearly show that after adopting the structure of this application, the mass flow distribution of each diversion region tends to be more balanced, and the low-speed retention phenomenon at the edge and far end of the flow field is significantly improved, effectively proving the positive role of the diversion channel structure in reducing dead zone risk and improving flow field uniformity.

[0068] It should be noted that, Figure 6 The results shown are mainly used to illustrate the basic working principle and technical effects of the present invention, and the specific values ​​do not constitute a limitation on the scope of protection of the present invention.

[0069] Furthermore, this application offers flexibility. It can be applied to fuel cell stacks that simultaneously employ the gradient flow channel structure on both the anode fuel side and the cathode air side to achieve optimal symmetry and uniformity. Alternatively, depending on specific performance or cost requirements, the flow channel structure can be installed only on one side (such as the fuel side or the air side), while the other side uses a conventional flow channel. For specific operating conditions with extremely high uniformity requirements, while maintaining the constricted design, the entire flow resistance network can be finely adjusted by optimizing the width of the main intake channel 1351, the number of flow channel microchannels 1353, and the specific grouping method of the array ribs, to achieve a better flow distribution effect.

[0070] In summary, the core of the planar solid oxide fuel cell stack proposed in this application lies in the synergistic design of a "narrowing" structure and a "gradually patterned array rib flow channel." The narrowing structure primarily serves to achieve a compact stack structure and shorten the sealing path, while the gradually patterned array rib flow channel aims to compensate for the uneven distribution of reactant gases that may be caused by the narrowing. The two work together to enable the stack to significantly reduce ineffective volume, improve volumetric power density and sealing reliability, while maintaining and even optimizing flow field uniformity, thus achieving comprehensive benefits in both structural design and fluid organization.

[0071] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A planar solid oxide fuel cell stack, characterized by, include: The fuel cell stack body includes multiple battery repeating units stacked along the stacking direction. Each battery repeating unit includes a single cell and metal connectors disposed on both sides of the single cell. The metal connectors are provided with an anode fuel inlet, an anode fuel outlet, a cathode air inlet, and a cathode air outlet, and the anode fuel inlet and outlet and the cathode air inlet and outlet form a crossflow configuration. The metal connectors are provided with anode fuel channels and cathode air channels on both sides along the thickness direction. The anode fuel channels are connected to the anode fuel inlet and the anode fuel outlet, respectively, and the cathode air channels are connected to the cathode air inlet and the cathode air outlet, respectively. The cavity housing assembly includes a first airflow cavity housing, a second airflow cavity housing, a third airflow cavity housing, and a fourth airflow cavity housing; Four airflow chambers are disposed around the main body of the fuel cell stack perpendicular to the stacking direction. The first airflow chamber is connected to the anode fuel inlet, the second airflow chamber is connected to the anode fuel outlet, the third airflow chamber is connected to the cathode air inlet, and the fourth airflow chamber is connected to the cathode air outlet. At least one of the anode fuel inlet, anode fuel outlet, cathode air inlet, and cathode air outlet has a projected area in the stacking direction that is smaller than the projected area of ​​the corresponding electrode active region in the same direction. At least one of the anode fuel channel and / or cathode air channel is configured as a split flow channel, which includes a main air intake channel, a main air outlet channel, and multiple split microchannels connecting the two. The main air intake channel is connected to the corresponding anode fuel inlet or cathode air inlet, and the main air outlet channel is connected to the corresponding anode fuel outlet or cathode air outlet. The split microchannels are formed by an array of ribs and flow in the direction of gas flow from the inlet side to the middle of the connector and then to the outlet side. The number of each group of ribs in the array first increases and then decreases, and the length of each group of ribs first decreases and then increases.

2. The planar solid oxide fuel cell stack of claim 1, wherein: The anode fuel inlet, anode fuel outlet, cathode air inlet, and cathode air outlet are all constricted, and their projected area in the stacking direction is smaller than the projected area of ​​the corresponding electrode active region in the same direction.

3. The planar solid oxide fuel cell stack of claim 1, wherein: The angle between the extension direction of the diversion microchannel in the diversion channel and the length direction of the main air intake channel and the main air outlet channel is 70° to 110°.

4. The planar solid oxide fuel cell stack of claim 3, wherein: The extension direction of the diversion microchannel is perpendicular to the length direction of the main air intake channel and the main air outlet channel.

5. The planar solid oxide fuel cell stack of claim 1, wherein: The cross-sectional area of ​​the main intake channel and the main exhaust channel is larger than the cross-sectional area of ​​any of the diversion microchannels; the orthographic projection of the main intake channel on the metal connector completely covers the corresponding cathode air inlet or anode fuel inlet; the orthographic projection of the main exhaust channel on the metal connector completely covers the corresponding cathode air outlet or anode fuel outlet.

6. The planar solid oxide fuel cell stack of claim 1, wherein: The array ribs are arranged in groups, with adjacent groups of array ribs arranged in parallel or approximately parallel, to guide airflow from the main air intake channel into each branch microchannel, and from each branch microchannel to the main air outlet channel.

7. The planar solid oxide fuel cell stack of claim 1, wherein: One side of the metal connector is provided with a first sealing area arranged around the anode fuel channel, and an anode sealing ring is provided in the first sealing area. The other side of the metal connector is provided with a second sealing area arranged around the cathode air channel, and a cathode sealing ring is provided in the second sealing area.

8. The planar solid oxide fuel cell stack of claim 1, wherein: The anode fuel channel and the cathode air channel adopt the same or mirrored split channel topology, and their gas inlet direction and gas outlet direction are set in opposite directions.

9. The planar solid oxide fuel cell stack as described in claim 1 or 2, characterized in that: The surface of the first airflow chamber shell is recessed to form a fuel intake channel. The fuel intake channel is connected to the anode fuel inlet through a fuel intake hole. A first sealing ring is provided between the first airflow chamber shell and the stack body to seal the connection between the fuel intake channel and the anode fuel inlet. The surface of the second airflow chamber shell is recessed to form a fuel outlet channel, which is connected to the anode fuel outlet through a fuel outlet hole; a second sealing ring is provided between the second airflow chamber shell and the stack body to seal the connection between the fuel outlet channel and the anode fuel outlet. The surface of the third airflow chamber shell is recessed to form an air intake channel, which is connected to the cathode air inlet through an air intake hole; a third sealing ring is provided between the third airflow chamber shell and the fuel cell body to seal the connection between the air intake channel and the cathode air inlet. The surface of the fourth airflow chamber shell is recessed to form an air outlet channel, which is connected to the cathode air outlet through an air outlet hole; a fourth sealing ring is provided between the fourth airflow chamber shell and the fuel cell body to seal the connection between the air outlet channel and the cathode air outlet.

10. The planar solid oxide fuel cell stack of claim 1, wherein: The fuel cell stack body further includes a top end plate connector, a bottom end plate connector, an upper insulating plate, a lower insulating plate, an upper cover plate, and a base. The top end plate connector and the bottom end plate connector are respectively located at the top and bottom of the fuel cell stack body. The upper insulating plate and the lower insulating plate are respectively located on the outside of the top end plate connector and the bottom end plate connector. The upper cover plate and the base are respectively located on the outside of the upper insulating plate and the lower insulating plate, and the upper cover plate and the base are fixedly connected by a first fastener. The first airflow chamber shell and the second airflow chamber shell, as well as the third airflow chamber shell and the fourth airflow chamber shell, are all fixedly connected by a second fastener.

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