A fuel cell stack and use thereof

Abstract

The present application relates to the technical field of fuel cell, in particular to a kind of fuel cell stack and its application.The application includes stack main body and the first stack end plate and the second stack end plate respectively arranged in the both ends of stack main body;Wherein stack main body has multiple cooling channels outside the top and bottom of reaction zone;The upper and lower sides of second stack end plate are each provided with circulating coolant inlet communicated with cooling channel, and the upper and lower sides of first stack end plate are each provided with circulating coolant outlet communicated with cooling channel.The present application reduces the width of bipolar plate, cools in side, uses heat conduction to export the heat inside the stack, simultaneously uses the heat transfer of side cooling flow channel to carry out heat, circulates heat dissipation, reduces volume, weight, to improve the specific power of stack.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a fuel cell stack and its applications. Background Technology

[0002] A fuel cell is a device that directly converts the chemical energy stored in a compound fuel into electrical energy through a chemical reaction. As the core component of a fuel cell, the bipolar plate plays many important roles, such as supporting the membrane electrode assembly, separating hydrogen and oxygen, collecting electrons, conducting heat, and providing cooling channels. Its performance largely depends on the flow field structure.

[0003] During battery operation, electrochemical reactions occur and generate a large amount of heat. To maintain the normal operating temperature of the battery stack, it is necessary to cool the stack. Traditional cooling coolant chambers, which are repeatedly stacked in a single cell, occupy a large volume and weight in the battery stack. As the power level of the battery stack increases, the proportion of coolant chambers becomes more and more significant. Therefore, it is becoming increasingly important to effectively maintain the temperature of the battery stack while reducing its volume and weight and improving its specific power. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a fuel cell stack and its application, thereby solving the problems of large size, heavy weight, and low specific power of traditional fuel cell stacks.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a fuel cell stack, comprising a stack body and a first stack end plate and a second stack end plate respectively disposed at both ends of the stack body; wherein the stack body has a plurality of cooling channels externally disposed at the top and bottom of the reaction zone; the second stack end plate is provided with circulating coolant inlets communicating with the cooling channels on its upper and lower sides, and the first stack end plate is provided with circulating coolant outlets communicating with the cooling channels on its upper and lower sides.

[0007] The main body of the fuel cell stack includes N membrane electrodes and N+1 bipolar plates stacked alternately in sequence, where N is an integer greater than or equal to three; an anode chamber and a cathode chamber are formed on both sides of each membrane electrode.

[0008] The bipolar plate has a fuel flow field at the anode and an oxidant flow field at the cathode on both sides, and multiple circulating coolant flow fields for forming the cooling channel are provided on the upper and lower sides of the bipolar plate.

[0009] The circulating coolant flow field has sealing grooves around its perimeter for installing sealing rings; the circulating coolant flow field has finned structures.

[0010] The bipolar plate has a rectangular structure. One end of the bipolar plate is provided with an anode fuel inlet and a cathode oxidant outlet. The other end of the bipolar plate is provided with an anode fuel outlet and a cathode oxidant inlet.

[0011] The fuel cell stack cathode oxidant outlet includes a first fuel cell stack cathode oxidant outlet and a second fuel cell stack cathode oxidant outlet, which are respectively located above and below the fuel cell stack anode fuel inlet;

[0012] The fuel cell stack cathode oxidant inlet includes a first fuel cell stack cathode oxidant inlet and a second fuel cell stack cathode oxidant inlet, which are respectively located above and below the fuel cell stack anode fuel outlet.

[0013] The two ends of the bipolar plate are respectively provided with needle-shaped and insert-type inspection structures to facilitate monitoring of the voltage of each individual cell.

[0014] The inner surfaces of the first and second fuel cell stack end plates are provided with multiple circulating coolant distribution plates, which correspond to the multiple cooling channels respectively.

[0015] A first insulating plate and a first current collector are provided between the first end plate of the fuel cell stack and one end of the fuel cell stack body; a second insulating plate and a second current collector are provided between the second end plate of the fuel cell stack and the other end of the fuel cell stack body. The first current collector and the second current collector are used for the current input and output of the fuel cell stack body; the first insulating plate and the second insulating plate serve as insulation.

[0016] The first fuel cell stack end plate, the fuel cell stack body, and the second fuel cell stack end plate are fastened together as one unit by fuel cell stack fastening straps.

[0017] Secondly, the present invention provides an application of a fuel cell stack as described in any of the preceding embodiments in the field of batteries.

[0018] The advantages and beneficial effects of this invention are as follows: The fuel cell stack and its application provided by this invention minimize the width of the bipolar plates, cool on the side, and use thermal conductivity to conduct heat out of the stack. At the same time, the heat is carried out by convection heat transfer through the side cooling channels, which effectively improves the uniformity of temperature distribution inside the bipolar plates. It changes the traditional design of alternating arrangement of cooling channels and reaction channels, and eliminates the coolant cavity in the stacking direction, which is conducive to reducing volume and weight, thereby improving the specific power of the stack. Attached Figure Description

[0019] Figure 1 This is an exploded schematic diagram of a fuel cell stack according to the present invention;

[0020] Figure 2This is one of the isometric views of a fuel cell stack according to the present invention;

[0021] Figure 3 This is the second isometric view of a fuel cell stack according to the present invention;

[0022] Figure 4 This is a schematic diagram of the structure of the bipolar plate of the fuel cell stack in this invention;

[0023] Figure 5 yes Figure 4 Rear view;

[0024] Figure 6 This is a schematic diagram of the sealing of the bipolar plate coolant chamber and various inlets and outlets in the fuel cell stack of this invention;

[0025] Figure 7 This is an isometric view of the main body of the fuel cell stack in this invention;

[0026] Figure 8 This is a schematic diagram of the structure of the fuel cell stack end plate II in this invention;

[0027] Figure 9 yes Figure 8 A magnified view of a portion of the image;

[0028] Figure 10 This is a schematic diagram of the T-shaped fins within the cooling channel in this invention;

[0029] Figure 11 These are comparison diagrams of the present invention and a conventional fuel cell stack repeating unit: (a) conventional fuel cell stack repeating unit, (b) novel fuel cell stack repeating unit;

[0030] Figure 12 This is a diagram showing the heat transfer effect of different bipolar plate structures and thermal conductivity in this invention.

[0031] In the diagram: 1. First fuel cell stack end plate, 2. Second fuel cell stack end plate, 3. First insulating plate, 4. First current collector plate, 5. Circulating coolant distribution plate, 6. Fuel flow field bipolar plate, 7. Fuel cell stack body, 8. Independent sealing groove, 9. Common sealing groove, 10. Fuel cell stack fastening strap, 11. Fuel cell stack membrane electrode, 12. Second insulating plate, 13. Second current collector plate, A. Fuel cell stack anode fuel inlet, B. Fuel cell stack anode fuel outlet, C. First fuel cell stack cathode oxidant inlet, D. Second fuel cell stack cathode oxidant inlet, E. First fuel cell stack cathode oxidant outlet, F. Second fuel cell stack cathode oxidant outlet G. First cycle coolant inlet, H. Second cycle coolant inlet, I. Third cycle coolant inlet, J. Fourth cycle coolant inlet, M. First cycle coolant outlet, N. Second cycle coolant outlet, L. Third cycle coolant outlet, K. Fourth cycle coolant outlet, O. Insert-type inspection port, P. Pin-type inspection port, QT type fin, a. Fuel flow field of stack anode, b. Oxidant flow field of stack cathode, c. Flow field of third cycle coolant, d. Flow field of fourth cycle coolant, e. Flow field of second cycle coolant, f. Flow field of first cycle coolant. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1-3 As shown, one aspect of the present invention provides a fuel cell stack, including a stack body 7 and a first stack end plate 1 and a second stack end plate 2 respectively disposed at both ends of the stack body 7; wherein the stack body 7 has multiple cooling channels externally disposed at the top and bottom of the reaction zone; the upper and lower sides of the second stack end plate 2 are provided with circulating coolant inlets communicating with the cooling channels, and the upper and lower sides of the first stack end plate 1 are provided with circulating coolant outlets communicating with the cooling channels.

[0034] Furthermore, such as Figure 1 As shown, a first insulating plate 3 and a first current collector 4 are provided between one end of the first fuel cell stack end plate 1 and one end of the fuel cell stack body 7; a second insulating plate 12 and a second current collector 13 are provided between the second fuel cell stack end plate 2 and the other end of the fuel cell stack body 7. The first current collector 4 and the second current collector 13 are used for current input and output of the fuel cell stack body 7; the first insulating plate 3 and the second insulating plate 12 serve as insulation.

[0035] like Figure 2-3As shown in the embodiment of the present invention, the first fuel cell stack end plate 1, the fuel cell stack body 7, and the second fuel cell stack end plate 2 are fastened together by fuel cell stack fastening straps 10. This fastening method saves space and ensures proper insulation to prevent short circuits caused by the straps contacting the fuel cell stack. The fuel cell stack is thus constrained by the fastening straps 10, significantly enhancing its resistance to shock and vibration, and preventing it from collapsing or deforming under impact loads.

[0036] In an embodiment of the present invention, the fuel cell stack body 7 includes N membrane electrodes and N+1 bipolar plates 6 stacked alternately in sequence, where N is an integer greater than or equal to three; an anode chamber and a cathode chamber are formed on both sides of each membrane electrode.

[0037] like Figure 4-5 As shown in the embodiment of the present invention, the bipolar plate 6 has a rectangular structure. The two side surfaces of the bipolar plate 6 are respectively provided with a fuel flow field a (a) for the anode and a oxidant flow field b (b) for the cathode. The flow field patterns can be parallel, serpentine, corrugated, etc., and turbulence can also be provided. Multiple circulating coolant flow fields for forming cooling channels are provided on the upper and lower sides of the bipolar plate 6. The upper and lower sides of the second stack end plate 2 are provided with circulating coolant inlets communicating with the cooling channels, and the upper and lower sides of the first stack end plate 1 are provided with circulating coolant outlets communicating with the cooling channels.

[0038] In this embodiment, a first circulating coolant flow field f and a second circulating coolant flow field e are provided on the lower long side of the bipolar plate 6, and a third circulating coolant flow field c and a fourth circulating coolant flow field d are provided on the upper long side of the bipolar plate 6, thus giving the fuel cell stack body 7 four cooling channels. Correspondingly, a first circulating coolant inlet G and a second circulating coolant inlet H are provided on the lower part of the second fuel cell stack end plate 2, and a third circulating coolant inlet I and a fourth circulating coolant inlet J are provided on the upper part of the second fuel cell stack end plate 2. A first circulating coolant outlet M and a second circulating coolant outlet N are provided on the lower long side of the first fuel cell stack end plate 1, and a third circulating coolant outlet L and a fourth circulating coolant outlet K are provided on the upper long side of the first fuel cell stack end plate 1. The first circulating coolant inlet G and the first circulating coolant outlet M are connected to the two ends of the first circulating coolant flow field f, respectively; the second circulating coolant inlet H and the second circulating coolant outlet N are connected to the two ends of the second circulating coolant flow field e, respectively; the third circulating coolant inlet I and the third circulating coolant outlet L are connected to the two ends of the third circulating coolant flow field c, respectively; and the fourth circulating coolant inlet J and the fourth circulating coolant outlet K are connected to the two ends of the fourth circulating coolant flow field d, respectively.

[0039] Furthermore, such as Figure 6 , Figure 10As shown, the four edges of the circulating coolant flow field are provided with sealing grooves for installing sealing rings; each circulating coolant flow field is provided with a fin structure. Preferably, the fin structure is a T-shaped fin Q, which can enhance heat transfer. The heat inside the fuel cell stack is first conducted from the middle to both sides by heat conduction, and then carried away by heat convection of the circulating liquid in the cooling channel.

[0040] like Figure 4-5 As shown in the embodiment of the present invention, one end of the bipolar plate 6 is provided with an anode fuel inlet A and a cathode oxidant outlet; the other end of the bipolar plate 6 is provided with an anode fuel outlet B and a cathode oxidant inlet. Sealing grooves are provided around the four edges of the anode fuel inlet A, the cathode oxidant outlet B, and the cathode oxidant inlet.

[0041] In this embodiment, the fuel cell stack cathode oxidant outlets include a first fuel cell stack cathode oxidant outlet E and a second fuel cell stack cathode oxidant outlet F, which are respectively located above and below the fuel cell stack anode fuel inlet A. The fuel cell stack cathode oxidant inlets include a first fuel cell stack cathode oxidant inlet C and a second fuel cell stack cathode oxidant inlet D, which are respectively located above and below the fuel cell stack anode fuel outlet B. Fuel enters from the fuel cell stack anode fuel inlet A located in the middle of the short side of one bipolar plate 6 and exits from the fuel cell stack anode fuel outlet B located in the middle of the short side of the other bipolar plate 6. Oxidant enters from the first fuel cell stack cathode oxidant inlet C and the second fuel cell stack cathode oxidant inlet D located on the short side of the other bipolar plate 6 and exits from the first fuel cell stack cathode oxidant outlet E and the second fuel cell stack cathode oxidant outlet F located on the other short side. The macroscopic flow directions of fuel and oxidant are opposite. The coolant flows through each cooling channel and does not enter the inner side of the fuel cell reactor reaction zone. Heat is conducted away from the fuel cell internally using bipolar plates, while heat is carried away by convection from the flowing medium in the side cooling channels, resulting in external circulation and heat dissipation. Multiple fin structures within the cooling channels enhance heat dissipation, and the macroscopic flow direction of the coolant on both sides can be the same or opposite.

[0042] Furthermore, needle-shaped and insert-type inspection structures are respectively provided at both ends of the bipolar plate 6 to facilitate monitoring of the voltage of each individual cell.

[0043] Furthermore, such as Figure 7-8 As shown, the inner surfaces of the first fuel cell stack end plate 1 and the second fuel cell stack end plate 2 are each provided with multiple circulating coolant distribution plates 5, which correspond to multiple cooling channels on the fuel cell stack body 7. The coolant enters the collecting channel from the coolant inlet, is evenly distributed by the circulating coolant distribution plates 5, and then enters each cooling channel c, d, e, and f of the fuel cell stack. After heat exchange, it enters the collecting channel at the outlet and flows out from the outlet.

[0044] like Figure 11As shown, the fuel cell stack of this invention minimizes the width of the bipolar plates 6, and differs from the conventional stack arrangement of repeated Oil1-Air-MEA-H2-Oil2-Air-MEA-H2 units, as shown in the figure. Figure 11 As shown in (a). This invention places the cold zone flow channel externally, forming first to fourth circulating coolant flow fields c, d, e, and f on the side. It utilizes thermal conductivity to remove heat from the fuel cell stack internally, while simultaneously using convective heat transfer through the side cooling channels to carry heat away, thus circulating heat dissipation and effectively improving the uniformity of temperature distribution within the bipolar plates. The fuel cell stack repeating unit is arranged in an Air-MEA-H2-MEA-Air repeating superposition pattern, as shown in (a). Figure 11 As shown in (b), this invention changes the traditional design of alternating cooling and reaction channels, eliminating the coolant cavity in the stacking direction, which is beneficial for reducing volume and weight, thereby improving the specific power of the fuel cell stack.

[0045] like Figure 10 As shown, the coolant chamber fins can be arranged as T-shaped fins Q, forming T-shaped or semi-T-shaped channels to increase the heat transfer area and improve the heat exchange capacity. They can also be arranged as other types of fins.

[0046] Assuming sufficient coolant flow rate (typically 50 L / min for a 10 kW fuel cell stack), the single-pool surface temperature difference can be estimated using the following formula:

[0047]

[0048] Where: l is the heat transfer distance (1 / 2 plate width), k is the thermal conductivity, q is the surface density of the heating power, and t is the thickness of the bipolar plate (usually the weighted thickness of the bipolar plate after removing the grooves).

[0049] like Figure 12 As shown, this demonstrates a single cell operating at a current density of 400 mA / cm². 2 Comparison of heat transfer under different thermal conductivity and plate thicknesses in a 0.6V operating condition and a bipolar plate width of 50mm structure: The figure shows that with a fixed bipolar plate width, a thicker bipolar plate results in a higher thermal conductivity and a smaller temperature difference across the bipolar plate plane. Furthermore, as the plate thickness and thermal conductivity decrease, the temperature difference increases exponentially. At a thermal conductivity of 100W / m... 2 At K, the planar temperature difference is ~5℃ when the bipolar plate thickness is 0.5mm; ~3℃ when the bipolar plate thickness is 1mm; ~2℃ when the bipolar plate thickness is 1.5mm; and ~1.5℃ when the bipolar plate thickness is 2mm. Other specific parameters can be found in [reference needed]. Figure 12 As shown.

[0050] like Figure 6As shown, each individual tank is sealed with a fluororubber coil. Due to the high operating pressure on the circulating coolant side, a double-seal line is used on the coolant side. There is an independent sealing groove 8 in the coolant side flow channel itself, with a built-in fluororubber coil. The inlet, outlet, and flow field of the other fuel and oxidant side flow channels use a common sealing groove 9. If a leak occurs in the coolant side flow channel, it will flow outside the fuel stack, which is conducive to timely detection and maintenance. More importantly, it prevents the coolant from leaking into the fuel or oxidant flow channels and damaging the fuel stack. The operating pressure on the fuel and oxidant sides is relatively low, so a single-seal or double-seal method can be used. The double-seal fluororubber coil enhances the reliability of the fuel stack seal.

[0051] The fuel cell stack of this invention is designed with a 300 cm² main reaction region for the membrane electrode. 2 Current density 400mA / cm 2 Operating at 0.6V, the device integrates 140 membrane electrodes and can output 10kW of power. As the number of integrated membrane electrodes increases, the power output will also increase. Multiple fuel cell stack modules can be combined in series or parallel to create a higher power output module. The size of the bipolar plate is not limited. Under the current material thermal conductivity conditions, to maintain an acceptable temperature difference within the bipolar plate, it is recommended that the bipolar plate width be <100mm. If the bipolar plate material has a higher thermal conductivity, or if it is lined with a high thermal conductivity material, the cooling effect will be better and the temperature difference within the single cell will be smaller.

[0052] In another aspect, the present invention provides an application of a fuel cell stack as described in any of the preceding embodiments in the field of batteries.

[0053] The fuel cell stack proposed in this invention minimizes the width of the bipolar plates and uses side cooling. It utilizes thermal conductivity to conduct heat out of the stack while simultaneously using convective heat transfer through the side cooling channels to carry away heat, thus circulating heat dissipation. This effectively improves the uniformity of temperature distribution inside the bipolar plates and changes the traditional design of alternating cooling and reaction channels. The coolant cavity is eliminated in the stacking direction, which is beneficial for reducing volume and weight, thereby improving the specific power of the stack.

[0054] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, extensions, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A fuel cell stack, characterized in that, It includes a fuel cell stack body (7) and a first fuel cell stack end plate (1) and a second fuel cell stack end plate (2) respectively disposed at both ends of the fuel cell stack body (7); wherein the fuel cell stack body (7) has multiple cooling channels externally located at the top and bottom of the reaction zone; the upper and lower sides of the second fuel cell stack end plate (2) are provided with circulating coolant inlets communicating with the cooling channels, and the upper and lower sides of the first fuel cell stack end plate (1) are provided with circulating coolant outlets communicating with the cooling channels; The main body (7) of the fuel cell stack includes N membrane electrodes and N+1 bipolar plates (6) stacked alternately in sequence, where N is an integer greater than or equal to three; an anode chamber and a cathode chamber are formed on both sides of each membrane electrode; the two sides of the bipolar plate (6) are respectively provided with a fuel flow field (a) of the fuel cell stack anode and an oxidant flow field (b) of the fuel cell stack cathode, and multiple circulating coolant flow fields for forming the cooling channel are provided on the upper and lower sides of the bipolar plate (6); The circulating coolant flow field has sealing grooves around its perimeter for installing sealing rings; the circulating coolant flow field has finned structures. The bipolar plate (6) has a rectangular structure. One end of the bipolar plate (6) is provided with an anode fuel inlet (A) and a cathode oxidant outlet. The other end of the bipolar plate (6) is provided with an anode fuel outlet (B) and a cathode oxidant inlet. The inner surfaces of the first fuel cell stack end plate (1) and the second fuel cell stack end plate (2) are provided with multiple circulating coolant distribution plates (5), and the circulating coolant distribution plates (5) correspond to the multiple cooling channels respectively.

2. The fuel cell stack according to claim 1, characterized in that, The fuel cell stack cathode oxidant outlet includes a first fuel cell stack cathode oxidant outlet (E) and a second fuel cell stack cathode oxidant outlet (F), which are respectively located above and below the fuel cell stack anode fuel inlet (A). The fuel cell stack cathode oxidant inlet includes a first fuel cell stack cathode oxidant inlet (C) and a second fuel cell stack cathode oxidant inlet (D), which are respectively located above and below the fuel cell stack anode fuel outlet (B).

3. The fuel cell stack according to claim 1, characterized in that, The two ends of the bipolar plate (6) are respectively provided with needle-shaped and insert-type inspection structures to facilitate monitoring of the voltage of each cell.

4. The fuel cell stack according to claim 1, characterized in that, A first insulating plate (3) and a first current collector (4) are provided between the first end plate (1) and one end of the main body (7); a second insulating plate (12) and a second current collector (13) are provided between the second end plate (2) and the other end of the main body (7). The first current collector (4) and the second current collector (13) are used for the current input and output of the main body (7); the first insulating plate (3) and the second insulating plate (12) serve as insulation.

5. The fuel cell stack according to claim 1, characterized in that, The first fuel cell stack end plate (1), the fuel cell stack body (7) and the second fuel cell stack end plate (2) are fastened together as one unit by fuel cell stack fastening straps (10).

6. An application of a fuel cell stack as described in any one of claims 1-5 in the field of batteries.

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