A fuel cell medium series-parallel stack structure

Abstract

The present invention relates to a fuel cell medium series-parallel stack structure, wherein the stack structure is formed by stacking in the order of a front end plate, a front insulating plate, a front current collecting plate, a first group of cells, a first dummy battery group, a second group of cells, a second dummy battery group, ..., the m+1th group of cells, a rear current collecting plate, a rear insulating plate, and a rear end plate; each dummy battery group is provided with a baffle, and the positions of the baffles of the dummy battery group are staggered according to the direction of gas flow, for blocking and changing the gas flow direction of the oxidant, and collecting and discharging the water generated by the reaction and the water carried by the oxidant. The number of cells in the m+1 group of cells decreases in sequence from the gas inlet to the outlet. The present invention forms a gradient grouped series gas supply according to the gas consumption law by changing the traditional parallel gas supply method, thereby improving the uniformity of gas distribution and flow speed, improving the drainage capacity of the stack, reducing the fuel cell metering ratio requirement, and reducing auxiliary power consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell medium series-parallel stack structure. Background Art

[0002] A fuel cell is a device that generates electricity through an electrochemical reaction between an oxidant and hydrogen fuel. The power generation process involves no moving parts, is silent, and produces water. It is environmentally friendly and highly efficient, offering broad application prospects in various energy and power sectors. As demand for fuel cell power continues to increase, the number of cells, reaction area, and current density in fuel cell stacks continues to increase, leading to two challenges in practical applications. First, the amount of water generated by the reaction increases, and the slow drainage rate causes flooding at the reaction interface, preventing further reaction and resulting in voltage fluctuations or even polarity reversal. Second, the increased number of cells leads to poor uniformity in the distribution of the medium between cells, resulting in poor cell voltage consistency and reduced overall stack efficiency and output power.

[0003] To address the flooding problem, the traditional approach is to optimize the flow field structure design of a single cell, using a serpentine flow field to reduce the gas flow area and increase the gas flow rate, or to use a variable cross-section flow channel design to increase the gas flow rate at the outlet of the flow channel. However, due to the limited gas flow rate distributed to a single cell, the optimization of the flow channel design at the single cell level has limited effect on improving the gas velocity, and leads to problems such as increased flow resistance, complex flow channel structure, and difficulty in processing. To address the problem of poor consistency of cell stacks, the traditional approach is to add dummy cells at the end of the stack so that several cells at the end with uneven gas distribution do not participate in power generation, but this does not essentially solve the problem of gas distribution consistency, or to set a wedge structure in the common flow channel of the fuel cell stack so that the cross-sectional area of ​​the common flow channel changes gradiently, thereby improving the uniformity of gas distribution between cells. However, this method results in problems such as a complex stack structure and poor matching of the wedge structure to stacks with different numbers of cells. Summary of the Invention

[0004] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, propose a fuel cell medium series-parallel stack structure, improve the uniformity of gas flow rate and the voltage consistency of the fuel cell single cell, and solve the problem of water flooding at the reaction interface.

[0005] The solution of the present invention is: a fuel cell medium series-parallel stack structure, including a front end plate, a front insulating plate, a front current collecting plate, m+1 groups of battery cells, m dummy battery groups, a rear current collecting plate, a rear insulating plate, and a rear end plate;

[0006] The stack structure adopts a grouped partitioning method, and is formed by stacking in the order of a front end plate, a front insulating plate, a front current collecting plate, a first group of cells, a first dummy battery group, ..., an i-th group of cells, an i-th dummy battery group, ..., an m-th group of cells, an m-th dummy battery group, an m+1-th group of cells, a rear current collecting plate, a rear insulating plate, and a rear end plate; wherein each component of the stack structure is provided with a cathode gas inlet through-hole, and all cathode gas inlet through-holes are connected to form a cathode gas inlet common flow channel; each component of the stack structure is provided with a cathode gas outlet through-hole, and all cathode gas outlet through-holes are connected to form a cathode gas outlet common flow channel, and at the same time, each component of the stack structure is provided with an internal flow channel connecting the cathode gas inlet through-hole and the cathode gas outlet through-hole; <i<m;

[0007] Each dummy battery group is provided with a partition part. The odd-numbered dummy battery groups are provided with a partition part at the through hole corresponding to the cathode air inlet common flow channel, and the even-numbered dummy battery groups are provided with a partition part at the through hole corresponding to the cathode air outlet common flow channel; the partition part is used to block and change the gas flow direction of the oxidant, and to gather the water generated by the reaction and the water carried in the oxidant and then flow through the cathode air inlet common flow channel and the cathode air outlet common flow channel for discharge.

[0008] Furthermore, the m+1 groups of battery cells are each formed by stacking multiple single cells, and each single cell is stacked in the order of cathode plate, membrane electrode, and anode plate. The cathode plates and anode plates of two adjacent single cells form a bipolar plate, forming a bipolar plate-membrane electrode repeating unit.

[0009] Furthermore, the number of single cells in the m+1 group of cells decreases in the direction from the gas inlet to the gas outlet.

[0010] Furthermore, the decreasing number of single batteries in the m+1 group of cells conforms to the decreasing law of the flow cross-sectional area that matches the law of gas consumption.

[0011] Furthermore, the dummy battery is formed by stacking the cathode plate, the dummy electrode, and the anode plate in order. The dummy electrode has the same shape and contour as the membrane electrode and is only used for gas blocking and conducting electricity.

[0012] Furthermore, the barrier portion is provided on the dummy battery at the middle position of each dummy battery group.

[0013] Furthermore, the barrier portion provided at the through hole corresponding to the cathode air intake common flow channel is located on the anode plate of the dummy electrode or dummy battery.

[0014] Furthermore, the barrier portion provided at the through hole corresponding to the cathode gas outlet common flow channel is located on the anode plate of the dummy electrode or dummy battery.

[0015] Furthermore, the number of dummy batteries in each dummy battery group is selected as follows: a power generation test is performed, liquid water generated by the reaction after the barrier is set is collected, and single batteries whose voltage fluctuations exceed a preset threshold due to the influence of liquid water are replaced with dummy batteries. The number of dummy batteries is determined as the minimum number of single batteries whose voltage fluctuations exceed a preset threshold due to the accumulation of liquid water after the barrier is set.

[0016] Furthermore, each component of the stack structure is provided with an anode gas inlet through-hole, and all the anode gas inlet through-holes are connected to form a common anode gas inlet flow channel; each component of the stack structure is provided with an anode gas outlet through-hole, and all the anode gas outlet through-holes are connected to form a common anode gas outlet flow channel; at the same time, each component of the stack structure is provided with an internal flow channel connecting the anode gas inlet through-hole and the anode gas outlet through-hole;

[0017] Each dummy battery pack is provided with a partition part. The odd-numbered dummy battery packs are provided with a partition part at the through hole corresponding to the anode air inlet common flow channel, and the even-numbered dummy battery packs are provided with a partition part at the through hole corresponding to the anode air outlet common flow channel.

[0018] The beneficial effects of the present invention compared with the prior art are:

[0019] (1) The present invention changes the method of supplying gas to n single cells in parallel through the common inlet and outlet flow channels of the fuel cell stack to m+1 groups of cells in series, thereby doubling the gas flow rate in the single cell flow channels within the cell, significantly improving the liquid water blowing effect, and enabling the fuel cell to have high drainage efficiency.

[0020] (2) The present invention replaces parallel gas supply with gradient grouped series gas supply, significantly reducing the number of cells supplied in parallel and improving the consistency of the cells in the stack. This solves the problem of poor gas distribution consistency and low gas flow at the end of the stack in the prior art, where hundreds of cells are supplied in parallel.

[0021] (3) The stack structure of the present invention is compatible with conventional fuel cell bipolar plate structures, eliminating the need for structural modification. Modification of metal stamped bipolar plates involves expensive mold costs. However, the present invention utilizes a novel lamination method based on the existing bipolar plate structure to achieve this modification. This modification requires only the addition of low-cost dummy cells and minor structural modifications to the stack's auxiliary components, resulting in a low-cost upgrade.

[0022] (4) The present invention can design a gradient of the number of grouped series cells for different media and fuel cell types to match different fuel cell application scenarios. For example, low-temperature proton exchange membrane fuel cells mainly consider gas consumption and drainage, while high-temperature proton exchange membrane fuel cells mainly consider gas consumption and changes in gas partial pressure caused by water vapor. In addition, the cathode and anode gases of the fuel cell can be designed in separate grouping modes to achieve uniform distribution and regulation of the media at both the positive and negative poles in one stack, which provides great design flexibility.

[0023] (5) The fuel cell system includes power-consuming components such as a gas circulation pump or a compressor to provide an excess supply of reaction medium to ensure that the electrochemical reaction proceeds fully. The present invention adopts a gradient grouping of the cell stack in series, so that the excess medium of the upstream cell can be consumed by the reaction of the downstream cell. Since the number of cells in the last group of cells is much smaller than the number of cells in the entire stack, the excess gas in the last group of cells accounts for a very small proportion compared to the entire stack, which can reduce the apparent metering ratio requirement of the stack, thereby reducing the demand for the circulation pump or compressor flow rate, and has a higher system benefit in terms of energy conversion rate and economic benefit. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the internal structure of a fuel cell medium series-parallel stack in Example 1 of the present invention;

[0025] Figure 2 This is a schematic diagram of the internal structure of a fuel cell medium series-parallel stack in Example 2 of the present invention;

[0026] Figure 3 It is a schematic diagram of the appearance of a fuel cell medium series-parallel stack according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the embodiments.

[0028] The fuel cell medium series-parallel stack structure described in the present invention is applied to low-temperature proton exchange membrane fuel cells, such as Figure 1 As shown, the fuel cell stack consists of a front end plate 1, a front insulating plate 2, a front current collecting plate 3, n single cells, m groups of dummy battery groups, a rear current collecting plate 9, a rear insulating plate 10, and a rear end plate 11. The n single cells are separated into m+1 groups of cells by the m groups of dummy battery groups. Figure 3 As shown, the front end plate 1 is provided with a cathode gas inlet 15, an anode gas inlet 17, a coolant inlet 19, and a coolant outlet 20; the rear end plate 11 is provided with a cathode gas outlet 16 and an anode gas outlet 18. Each component has a through-hole at a position corresponding to the cathode gas inlet 15, and the overlapping through-holes form a common cathode gas inlet flow channel 21. Each component has a through-hole at a position corresponding to the cathode gas outlet 16, and the overlapping through-holes form a common cathode gas outlet flow channel 22.

[0029] like Figure 1 In this embodiment, m is 2, and the fuel cell stack structure is formed by stacking in the order of front end plate 1-front insulating plate 2-front current collecting plate 3-anode plate-first group of cells 12-first group of dummy batteries-second group of cells 13-second group of dummy batteries-third group of cells 14-cathode plate-rear current collecting plate 9-rear insulating plate 10-rear end plate 11. Each group of cells is composed of multiple single cells connected in series, and the gas flow direction of the single cells in the same group of cells is the same, forming a parallel gas flow direction. Each single cell is composed of a cathode plate 4-membrane electrode 5-anode plate 6 stack. The cathode plate 4 and anode plate 6 of two adjacent single cells can form a bipolar plate, thereby forming a bipolar plate-membrane electrode repeating unit. The cathode plate 4 has a cathode flow channel for the circulation of oxidant (air or oxygen) and liquid water, and the anode plate 6 has an anode flow channel for the circulation of hydrogen. The total number of cells in the first group of cells 12 , the second group of cells 13 , and the third group of cells 14 is n, and the number of cells in the three groups of cells decreases in sequence from the gas inlet to the gas outlet.

[0030] Each dummy battery is composed of a cathode plate-dummy electrode 8-anode plate. The cathode plate and anode plate of the dummy battery are the same as those of a single battery. The shape and contour of the dummy electrode 8 are the same as those of the membrane electrode 5, but it is not the place where the electrochemical reaction occurs. It only serves to block gas and conduct electricity.

[0031] A barrier is provided in any dummy cell of each dummy battery pack. The oxidant is blocked by the barrier and redirected. The water generated by the reaction and the water carried by the oxidant diffuse in the cathode flow channels of the dummy battery pack and are discharged through the cathode inlet common flow channel 21 and the cathode outlet common flow channel 22, thereby preventing flooding of the reaction interface in the single cell. The barrier is preferably provided on the dummy cell in the middle of the dummy battery pack. Specifically, the barrier can be provided on the dummy electrode 8 or the cathode plate.

[0032] In addition, the cathode and anode gases of the fuel cell can be designed and grouped separately to achieve uniform distribution and regulation of the media at the anode and cathode poles in one fuel cell stack, which provides great design flexibility.

[0033] Example 1

[0034] like Figure 1As shown, in one dummy cell of the first dummy battery group, the dummy electrode 8 is blocked at the location where the cathode inlet common flow channel 21 passes, forming a first barrier 71. In one dummy cell of the second dummy battery group, the dummy electrode 8 is blocked at the location where the cathode outlet common flow channel 22 passes, forming a second barrier 72. The provision of the barriers creates m blocked locations in the common channels for the fuel cell's inlet and outlet gases. Oxidant enters from the cathode inlet common flow channel 21 and reacts from left to right through each cell of the first group of cells 12. After passing through the first barrier 71, the remaining oxidant's flow is blocked and redirected, flowing from the cathode flow channel of the dummy cell before the barrier occurs into the cathode outlet common flow channel 22. Each cell of the second group of cells 13 then reacts after receiving oxidant from the cathode outlet common flow channel 22 from right to left. After the remaining oxidant passes through the second barrier 72, its flow is blocked and redirected again, flowing from the cathode flow channel of the dummy battery before the barrier occurred into the cathode gas inlet common flow channel 21. Each cell in the third group of cells 14 then receives oxidant from left to right through the cathode gas inlet common flow channel 21 and reacts. This flow pattern continues until the final reaction, when the remaining oxidant is discharged from the cathode gas outlet 16. Therefore, the barrier changes the gas supply direction of the cells from n parallel connections to m series connections, dividing the n cells into m+1 groups of cells (the gas supply direction of each cell within the group remains in parallel).

[0035] The performance uniformity of a single cell in a fuel cell stack depends largely on the consistency of the flow distribution of gas supplied to each single cell. In traditional fuel cells, as the number of single cells increases, the uniformity of the gas flow distributed from the common flow channel of the fuel cell in parallel (referring to the direction of gas flow) to the single cell gradually deteriorates. The closer the single cell is to the end of the common flow channel, the smaller the gas flow distributed, and the worse the performance of the single cell. When the stack structure described in the present invention is adopted, all single cells with gas supplied in parallel are supplied with gas in series m times between the cells, the average number of single cells with gas supplied in parallel (the average here is because the number of single cells in each group of cells can be decreasing, and the average value is simplified here) is shortened to 1 / m, which significantly reduces the number of single cells with gas supplied in parallel and improves the consistency of gas flow distribution of single cells.

[0036] Furthermore, the series flow of gas between the m groups of cells increases the flow path length and pressure drop. This increase in pressure drop per cell also facilitates consistent gas distribution between cells supplied in parallel, improving the consistency of each group of cells.

[0037] The cathode flow channel of the dummy cell is also used to circulate the water generated by the fuel cell reaction and the water carried by the oxidant. Figure 1As shown, the water generated by the reaction of the first group of cells 12 and the water carried by the oxidant are blocked and collected by the first barrier 71. They diffuse in the direction of the arrows through the dummy battery cathode channels on both sides of the first barrier 71 to the cathode inlet common flow channel 21 and the cathode outlet common flow channel 22. The water generated by the reaction of the first group of cells 12, the water generated by the reaction of the second group of cells 13, and the water carried by the oxidant are blocked and collected by the barrier 72. They diffuse in the direction of the arrows through the dummy battery cathode channels on both sides of the second barrier 72 to the cathode inlet common flow channel 21 and the cathode outlet common flow channel 22. The liquid water continues to flow within the cathode inlet common flow channel 21, eventually reaching the cathode outlet common flow channel 22 through the cathode flow channel adjacent to the current collector 9, and exiting the stack through the cathode gas outlet 16. Therefore, by providing a barrier to collect the liquid water and replacing cells with dummy cells that are severely flooded, the present invention solves the problem of liquid water flooding the membrane electrode, preventing further reaction, causing voltage fluctuations and even polarity reversal.

[0038] A principle for selecting the number of dummy cells is provided: The number of dummy cells should be determined based on the total number of cells in the fuel cell stack and the water production. Power generation tests should be conducted to confirm the number of cells near the barrier that experience significant voltage fluctuations due to the presence of liquid water, and these cells should be replaced with dummy cells. At the same time, excessive dummy cells should be avoided to avoid unnecessary additional gas flow, resulting in gas waste or increased power consumption in the circulation pump. Therefore, the number of dummy cells should be determined to be the minimum number of cells whose electrical performance is significantly affected by liquid water accumulation near the barrier.

[0039] The two partitions in this embodiment divide the single cells into three groups, namely the first group of battery cells 12, the second group of battery cells 13 and the third group of battery cells 14. The gas medium of these three groups of battery cells is connected in series in sequence. In this embodiment, the first group of battery cells 12 contains 4 single cells, and the gas medium of these 4 single cells is supplied in parallel by the cathode air inlet common flow channel 21. Similarly, the single cells in other groups of battery cells are also in the intra-group parallel gas supply mode. From the first group of battery cells 12 to the last third group of battery cells 14, in order to balance the gas flow rate of all single cell flow channels in the battery stack, the number of single cells in the battery cell gradually decreases, and a flow cross-sectional area decreasing law that matches the gas consumption law can be adopted, including arithmetic decrease, geometric decrease and other methods.

[0040] Assuming a gas consumption flow rate of 1 SLPM per cell under rated operating conditions and an oxygen flow rate of 8 SLPM supplied from the cathode gas inlet 15, the gas flow rate and stoichiometric ratio of the cells within each group of cells are shown in Table 1. This demonstrates that the gradient grouping and serial connection, with a gradually decreasing number of cells, achieves a balanced stoichiometric ratio for all cells in the stack, ensuring a high stoichiometric ratio (2 in this embodiment) for all cells in the stack. This improves electrochemical reaction performance and water management efficiency. Furthermore, a very low apparent stoichiometric ratio (1.14 in this embodiment) is achieved, reducing flow requirements for circulation pumps, compressors, and other components, thereby enhancing the system efficiency of the fuel cell.

[0041] Table 1 Comparison of apparent and grouped gas parameters of fuel cell stack

[0042]

[0043] Example 2

[0044] like Figure 2 As shown, in one dummy cell of the first group of dummy batteries, the anode plate is blocked at the location where the cathode inlet common flow channel 21 passes, forming a third barrier 73. In one dummy cell of the second group of dummy batteries, the anode plate is blocked at the location where the cathode outlet common flow channel 22 passes, forming a fourth barrier 74. The provision of the barriers creates m blocked locations in the common channels for the fuel cell's inlet and outlet gases. Oxidant enters through the cathode inlet common flow channel 21 and reacts from left to right through each cell of the first group of cells 12. After the remaining oxidant passes through the third barrier 73, its flow is blocked and redirected, flowing from the cathode flow channel of the dummy cell before the barrier occurs into the cathode outlet common flow channel 22. Each cell of the second group of cells 13 then reacts after receiving oxidant from the cathode outlet common flow channel 22 from right to left. After the remaining oxidant passes through the fourth barrier 74, the gas flow is blocked and changes direction again, flowing from the cathode flow channel of the dummy cell before the barrier occurs into the cathode gas inlet common flow channel 21. Each cell of the third group of cells 14 is fed with oxidant from left to right through the cathode gas inlet common flow channel 21 and reacts. This flow pattern continues until the remaining oxidant is discharged from the cathode gas outlet 16 after the final reaction. Therefore, the barrier changes the gas supply direction of the cells from n times in parallel to m times in series, dividing the n cells into m+1 groups of cells (the gas supply direction of each cell in the cell group is still in parallel), thereby improving the voltage consistency of the fuel cell cells.

[0045] The cathode flow channel of the dummy cell is also used to circulate the water generated by the fuel cell reaction and the water carried by the oxidant. Figure 2As shown, the water generated by the reaction of the first group of cells 12 and the water carried by the oxidant are blocked and collected by the third barrier 73. They diffuse in the direction of the arrows through the dummy battery cathode channels on both sides of the third barrier 73 to the cathode inlet common flow channel 21 and the cathode outlet common flow channel 22. The water generated by the reaction of the first group of cells 12, the water generated by the reaction of the second group of cells 13, and the water carried by the oxidant are blocked and collected by the barrier 74. They diffuse in the direction of the arrows through the dummy battery cathode channels on both sides of the fourth barrier 74 to the cathode inlet common flow channel 21 and the cathode outlet common flow channel 22. The liquid water continues to flow within the cathode inlet common flow channel 21, eventually passing through the cathode flow channel adjacent to the current collector 9 to the cathode outlet common flow channel 22, and then exits the stack through the cathode gas outlet 16. By providing barrier closures to collect the liquid water and replacing severely flooded cells with dummy cells, the problem of liquid water flooding the membrane electrode, preventing further reaction, and causing voltage fluctuations or even polarity reversal, is resolved.

[0046] A principle for selecting the number of dummy cells is provided: The number of dummy cells should be determined based on the total number of cells in the fuel cell stack and the water production. Power generation tests should be conducted to confirm the number of cells near the barrier that experience significant voltage fluctuations due to the presence of liquid water, and these cells should be replaced with dummy cells. At the same time, excessive dummy cells should be avoided to avoid unnecessary additional gas flow, resulting in gas waste or increased power consumption in the circulation pump. Therefore, the number of dummy cells should be determined to be the minimum number of cells whose electrical performance is significantly affected by liquid water accumulation near the barrier.

[0047] The two partitions in this embodiment divide the single cells into three groups, namely the first group of battery cells 12, the second group of battery cells 13 and the third group of battery cells 14. The gas medium of these three groups of battery cells is connected in series in sequence. In this embodiment, the first group of battery cells 12 contains 4 single cells, and the gas medium of these 4 single cells is supplied in parallel by the cathode air inlet common flow channel 21. Similarly, the single cells in other groups of battery cells are also in the intra-group parallel gas supply mode. From the first group of battery cells 12 to the last third group of battery cells 14, in order to balance the gas flow rate of all single cell flow channels in the battery stack, the number of single cells in the battery cell gradually decreases, and a flow cross-sectional area decreasing law that matches the gas consumption law can be adopted, including arithmetic decrease, geometric decrease and other methods.

[0048] Assuming a gas consumption flow rate of 1 SLPM per cell under rated operating conditions and an oxygen flow rate of 8 SLPM supplied from the cathode gas inlet 15, the gas flow rate and stoichiometric ratio of the cells within each group of cells are shown in Table 2. This shows that the gradient grouping and serial connection of cells, with a gradually decreasing number of cells, achieves a balanced stoichiometric ratio for all cells in the stack, ensuring that all cells in the stack have a high stoichiometric ratio (2 in this embodiment), which is beneficial for improving electrochemical reaction performance and water management efficiency. Furthermore, a very low apparent stoichiometric ratio (1.14 in this embodiment) is achieved, reducing the flow requirements for circulation pumps, compressors, and other components, thereby improving the system efficiency of the fuel cell.

[0049] Table 2 Comparison of apparent and grouped gas parameters of fuel cell stack

[0050]

[0051] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A fuel cell medium series-parallel stack structure, characterized in that: It includes a front end plate, a front insulating plate, a front current collecting plate, m+1 groups of battery cells, m dummy battery groups, a rear current collecting plate, a rear insulating plate, and a rear end plate; The stack structure adopts a grouped partitioning method and is formed by stacking in the order of a front end plate, a front insulating plate, a front current collecting plate, a first group of cells, a first dummy battery group, ..., an i-th group of cells, an i-th dummy battery group, ..., an m-th group of cells, an m-th dummy battery group, an m+1-th group of cells, a rear current collecting plate, a rear insulating plate, and a rear end plate; wherein each component of the stack structure is provided with a cathode gas inlet through-hole, and all the cathode gas inlet through-holes are connected to form a cathode gas inlet common flow channel (21); each component of the stack structure is provided with a cathode gas outlet through-hole, and all the cathode gas outlet through-holes are connected to form a cathode gas outlet common flow channel (22); at the same time, each component of the stack structure is provided with an internal flow channel connecting the cathode gas inlet through-hole and the cathode gas outlet through-hole; <i<m; Each dummy battery group is provided with a barrier portion. The odd-numbered dummy battery groups are provided with a barrier portion at a through hole corresponding to the cathode gas inlet common flow channel (21), and the even-numbered dummy battery groups are provided with a barrier portion at a through hole corresponding to the cathode gas outlet common flow channel (22); the barrier portion is used to block and change the gas flow direction of the oxidant, and to gather the water generated by the reaction and the water carried by the oxidant and then flow through the cathode gas inlet common flow channel (21) and the cathode gas outlet common flow channel (22) for discharge; The number of cells in group m+1 decreases from the gas inlet to the gas outlet; Each dummy battery in the dummy battery group is formed by stacking a cathode plate, a dummy electrode, and an anode plate in this order. The dummy electrode has the same shape and contour as the membrane electrode and is only used for gas blocking and conducting electricity.

2. A fuel cell medium series-parallel stack structure according to claim 1, characterized in that: The m+1 groups of battery cells are each formed by stacking multiple single cells, each of which is stacked in the order of cathode plate, membrane electrode, and anode plate. The cathode plates and anode plates of two adjacent single cells form a bipolar plate, forming a bipolar plate-membrane electrode repeating unit.

3. A fuel cell medium series-parallel stack structure according to claim 1, characterized in that: The decreasing number of single batteries in the m+1 group of cells conforms to the decreasing law of the flow cross-sectional area that matches the law of gas consumption.

4. A fuel cell medium series-parallel stack structure according to claim 1, characterized in that: The barrier portion is arranged on the dummy battery at the middle position of each dummy battery group.

5. The fuel cell medium series-parallel stack structure according to claim 1, characterized in that: The barrier portion provided at the through hole corresponding to the cathode air inlet common flow channel (21) is located on the anode plate of the dummy electrode or dummy battery.

6. A fuel cell medium series-parallel stack structure according to claim 1, characterized in that: The barrier portion provided at the through hole corresponding to the cathode gas outlet common flow channel (22) is located on the anode plate of the dummy electrode or dummy battery.

7. The fuel cell medium series-parallel stack structure according to claim 1, characterized in that: The number of fake batteries in each fake battery group is selected as follows: a power generation test is performed, and the liquid water generated by the reaction after the barrier is set is collected, and the single battery whose voltage fluctuation exceeds the preset threshold due to the influence of liquid water is replaced with a fake battery. The number of fake batteries is determined as the minimum number of single batteries whose voltage fluctuation exceeds the preset threshold due to the accumulation of liquid water after the barrier is set.

8. The fuel cell medium series-parallel stack structure according to claim 1, characterized in that: Each component of the stack structure is provided with an anode gas inlet through-hole, and all the anode gas inlet through-holes are connected to form a common anode gas inlet flow channel; each component of the stack structure is provided with an anode gas outlet through-hole, and all the anode gas outlet through-holes are connected to form a common anode gas outlet flow channel. At the same time, each component of the stack structure is provided with an internal flow channel connecting the anode gas inlet through-hole and the anode gas outlet through-hole; Each dummy battery pack is provided with a partition part. The odd-numbered dummy battery packs are provided with a partition part at the through hole corresponding to the anode air inlet common flow channel, and the even-numbered dummy battery packs are provided with a partition part at the through hole corresponding to the anode air outlet common flow channel.

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