Fuel cell stack and application thereof

Abstract

The invention relates to the technical field of fuel cells, in particular to a fuel cell stack and application thereof. Comprising a galvanic pile main body, a first galvanic pile end plate and a second galvanic pile end plate, wherein the electric pile main body is provided with a plurality of cooling channels which are externally arranged at the top and the bottom of a reaction area; circulating coolant inlets communicated with the cooling channel are formed in the upper side and the lower side of the second electric pile end plate; circulating coolant outlets communicated with the cooling channel are formed in the upper side and the lower side of the first electric pile end plate. According to the invention, the width of the bipolar plate is reduced, cooling is carried out on the side surface, heat in the stack is led out by heat conduction, and meanwhile, the heat is brought out by convective heat transfer of the cooling flow channels on the side surface, so that the volume and the weight are reduced, and the specific power of the stack is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell stack and applications thereof. Background Art

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

[0003] During battery operation, a large amount of heat is generated when electrochemical reactions occur. In order to maintain the normal operating temperature of the battery stack, the battery stack needs to be cooled. The traditional cooling coolant chamber that is repeatedly superimposed on the single cell occupies a large volume and weight in the battery stack. As the power level of the battery stack increases, it becomes more and more important to effectively maintain the temperature of the battery stack while reducing the volume and weight and improving the power density of the battery stack. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a fuel cell stack and its application to solve the problems of large size, heavy weight and low specific power of traditional fuel cell stacks.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In the first aspect, the present invention provides a fuel cell stack, including a stack body and a first stack end plate and a second stack end plate respectively arranged at both ends of the stack body; wherein the stack body has a plurality of cooling channels externally arranged at the top and bottom of the reaction zone; the upper and lower sides of the second stack end plate are provided with a circulating coolant inlet connected to the cooling channel, and the upper and lower sides of the first stack end plate are provided with a circulating coolant outlet connected to the cooling channel.

[0007] The battery stack body includes N membrane electrodes and N+1 bipolar plates which are alternately stacked 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 two side surfaces of the bipolar plate are respectively provided with a stack anode fuel flow field and a stack cathode oxidant flow field, and a plurality of circulating coolant flow fields for forming the cooling channel are provided on the upper and lower sides of the bipolar plate.

[0009] Sealing grooves for installing sealing rings are arranged on the edges of the circulating coolant flow field; and a fin structure is arranged inside the circulating coolant flow field.

[0010] The bipolar plate is a rectangular structure, and one end of the bipolar plate is provided with a stack anode fuel inlet and a stack cathode oxidant outlet; the other end of the bipolar plate is provided with a stack anode fuel outlet and a stack cathode oxidant inlet.

[0011] The stack cathode oxidant outlet comprises a first stack cathode oxidant outlet and a second stack cathode oxidant outlet, and the first stack cathode oxidant outlet and the second stack cathode oxidant outlet are respectively arranged at the upper and lower sides of the stack anode fuel inlet;

[0012] The stack cathode oxidant inlet comprises a first stack cathode oxidant inlet and a second stack cathode oxidant inlet, and the first stack cathode oxidant inlet and the second stack cathode oxidant inlet are respectively arranged at the upper and lower sides of the stack anode fuel outlet.

[0013] The two ends of the bipolar plate are respectively provided with a needle-shaped and a plug-in type inspection structure to facilitate the monitoring of the voltage of each single cell.

[0014] The inner side surfaces of the first stack end plate and the second stack end plate are both provided with a plurality of circulating coolant uniform distribution plates, and the circulating coolant uniform distribution plates correspond to the plurality of cooling channels respectively.

[0015] A first insulating plate and a first current collecting plate are provided between the first stack end plate and one end of the stack body; a second insulating plate and a second current collecting plate are provided between the second stack end plate and the other end of the stack body, and the first current collecting plate and the second current collecting plate are used for current input and output of the stack body; the first insulating plate and the second insulating plate play an insulating role.

[0016] The first stack end plate, the stack body and the second stack end plate are fastened together by a stack fastening strap.

[0017] In a second aspect, the present invention provides an application of a fuel cell stack as described in any one of the preceding embodiments in the battery field.

[0018] The advantages and beneficial effects of the present invention are as follows: a fuel cell stack and its application provided by the present invention minimizes the width of the bipolar plate, cools the side, uses heat conduction to export the heat inside the stack, and uses convective heat transfer in the side cooling channel to bring the heat out, circulates the heat, effectively improves the uniformity of temperature distribution inside the bipolar plate, changes the design of alternating arrangement of traditional cooling channels and reaction channels, eliminates the coolant cavity in the stacking direction, is beneficial to reduce volume and weight, and thus improves the specific power of the stack. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0020] Figure 2It is one of the axonometric views of a fuel cell stack of the present invention;

[0021] Figure 3 This is the second axonometric diagram of a fuel cell stack of the present invention;

[0022] Figure 4 It is a schematic diagram of the structure of the bipolar plate of the battery stack in the present invention;

[0023] Figure 5 yes Figure 4 Rear view of

[0024] Figure 6 It is a schematic diagram of the sealing of the coolant cavity and each inlet and outlet of the battery stack bipolar plate in the present invention;

[0025] Figure 7 It is an axonometric view of the battery stack body in the present invention;

[0026] Figure 8 It is a structural schematic diagram of the stack end plate II in the present invention;

[0027] Fig. 9 yes Figure 8 A partial enlarged view of

[0028] Fig.10 It is a schematic diagram of the structure of the T-shaped fin in the cooling channel of the present invention;

[0029] Fig.11 This is a comparison diagram between the present invention and the traditional battery stack repeating unit: (a). Traditional battery stack repeating unit, (b). New battery stack repeating unit;

[0030] Fig.12 It is a heat transfer effect diagram of different bipolar plate structures and thermal conductivity coefficients in the present invention.

[0031] In the figure: 1. First stack end plate, 2. Second stack end plate, 3. First insulating plate, 4. First current collector, 5. Circulating coolant uniform distribution plate, 6. Fuel flow field bipolar plate, 7. Stack body, 8. Independent sealing groove, 9 Common sealing groove, 10. Stack fastening strap, 11. Stack membrane electrode, 12. Second insulating plate, 13. Second current collector, A. Stack anode fuel inlet, B. Stack anode fuel outlet, C. First stack cathode oxidant inlet, D. Second stack cathode oxidant inlet, E. First stack cathode oxidant outlet, F. Second stack cathode oxidant outlet Mouth, G. First circulation coolant inlet, H. Second circulation coolant inlet, I. Third circulation coolant inlet, J. Fourth circulation coolant inlet, M. First circulation coolant outlet, N. Second circulation coolant outlet, L. Third circulation coolant outlet, K. Fourth circulation coolant outlet, O. Insert type inspection hole, P. Pin type inspection hole, QT type fin, a. Anode fuel flow field of fuel cell stack, b. Cathode oxidant flow field of fuel cell stack, c. Third circulation coolant flow field, d. Fourth circulation coolant flow field, e. Second circulation coolant flow field, f. First circulation coolant flow field. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1-3 As shown, on one hand, 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 arranged at both ends of the stack body 7; wherein the stack body 7 has a plurality of cooling channels externally arranged at the top and bottom of the reaction zone; the upper and lower sides of the second stack end plate 2 are provided with a circulating coolant inlet connected to the cooling channel, and the upper and lower sides of the first stack end plate 1 are provided with a circulating coolant outlet connected to the cooling channel.

[0034] Furthermore, if Figure 1 As shown, a first insulating plate 3 and a first current collecting plate 4 are provided between the first stack end plate 1 and one end of the stack body 7; a second insulating plate 12 and a second current collecting plate 13 are provided between the second stack end plate 2 and the other end of the stack body 7, and the first current collecting plate 4 and the second current collecting plate 13 are used for current input and output of the stack body 7; the first insulating plate 3 and the second insulating plate 12 play an insulating role.

[0035] like Figure 2-3As shown, in the embodiment of the present invention, the first stack end plate 1, the stack body 7 and the second stack end plate 2 are fastened together by the stack fastening band 10. The stack is fastened by a band, which saves space, and at the same time, insulation is done to prevent the band from contacting the stack to cause short circuits, etc. The stack fastening band 10 is used to restrain the stack as a whole, which greatly enhances the stack's anti-impact and vibration performance, and prevents the stack from "collapse" or deformation when subjected to impact loads.

[0036] In the embodiment of the present invention, the battery stack body 7 includes N membrane electrodes and N+1 bipolar plates 6 which are alternately stacked 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 is a rectangular structure, and the two side surfaces of the bipolar plate 6 are respectively provided with a stack anode fuel flow field a and a stack cathode oxidant flow field b, and the flow field modes are parallel, serpentine, corrugated, etc., and turbulence can also be set. A plurality of 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 a circulating coolant inlet connected to the cooling channel, and the upper and lower sides of the first stack end plate 1 are provided with a circulating coolant outlet connected to the cooling channel.

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

[0039] Furthermore, if Figure 6 , Fig.10As shown, the 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 stack is first conducted from the middle to both sides, and then carried away by convection of the circulating fluid 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 a stack anode fuel inlet A and a stack cathode oxidant outlet; the other end of the bipolar plate 6 is provided with a stack anode fuel outlet B and a stack cathode oxidant inlet. The edges of the stack anode fuel inlet A, the stack cathode oxidant outlet, the stack anode fuel outlet B and the stack cathode oxidant inlet are all provided with sealing grooves.

[0041] In this embodiment, the cathode oxidant outlet of the stack includes a first cathode oxidant outlet E and a second cathode oxidant outlet F, and the first cathode oxidant outlet E and the second cathode oxidant outlet F are respectively arranged on the upper and lower sides of the anode fuel inlet A of the stack. The cathode oxidant inlet of the stack includes a first cathode oxidant inlet C and a second cathode oxidant inlet D of the stack, and the first cathode oxidant inlet C and the second cathode oxidant inlet D of the stack are respectively arranged on the upper and lower sides of the anode fuel outlet B of the stack. The fuel enters from the anode fuel inlet A of the stack in the middle of the short side of one side of the bipolar plate 6, and is discharged from the anode fuel outlet B of the stack in the middle of the short side of the other side of the bipolar plate 6. The oxidant enters from the first cathode oxidant inlet C and the second cathode oxidant inlet D of the stack on one short side of another bipolar plate 6, and is discharged from the first cathode oxidant outlet E and the second cathode oxidant outlet F of the stack on the other short side, and the macroscopic flow direction of the fuel and the oxidant is opposite. The coolant flows through each cooling channel and does not enter the inner side of the stack reaction area. The heat of the stack is conducted internally by the bipolar plate, and the heat is taken out by the convection heat transfer of the flowing medium in the side cooling channel, and the heat is circulated externally. The various fin structures in the cooling channel can improve the heat dissipation effect, 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 single cell.

[0043] Furthermore, if Figure 7-8 As shown, the inner side surfaces of the first stack end plate 1 and the second stack end plate 2 are both provided with a plurality of circulating coolant uniform distribution plates 5, and the circulating coolant uniform distribution plates 5 correspond to the plurality of cooling channels on the stack body 7. The coolant enters the collecting channel from the coolant inlet, is evenly distributed through the circulating coolant uniform distribution plate 5, and enters each cooling channel c, d, e, and f of the stack, enters the collecting channel at the outlet after heat exchange, and flows out from the outlet.

[0044] like Fig.11As shown, the fuel cell stack of the present invention minimizes the width of the bipolar plate 6, and is different from the arrangement of the conventional stack repeating units Oil1-Air-MEA-H2-Oil2-Air-MEA-H2, such as Fig.11 (a) As shown. The present invention places the cold zone flow channel externally, and forms the first to fourth circulating coolant flow fields c, d, e, and f on the side, and uses heat conduction to remove the heat from the stack internally, while using the side cooling flow channel to carry out the heat by convection heat transfer, circulating the heat, and effectively improving the uniformity of the temperature distribution inside the bipolar plate. The stack repeating unit is the arrangement form of repeated superposition of Air-MEA-H2-MEA-Air, as shown in FIG. Fig.11 The present invention changes the traditional design of alternating arrangement of cooling channels and reaction channels, and eliminates the coolant cavity in the stacking direction, which is beneficial to reducing the volume and weight, thereby improving the specific power of the fuel cell stack.

[0045] like Fig.10 As shown, the coolant chamber fins can be arranged into T-shaped fins Q, forming T-shaped or semi-T-shaped channels, increasing the heat transfer area and improving the heat exchange capacity, and can also be arranged into other forms of fins.

[0046] Under the premise of ensuring the coolant flow rate (usually a 10kW stack corresponds to a 50L / min circulating coolant flow rate), the temperature difference of a single cell plane 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 heating power surface density, and t is the bipolar plate thickness (usually the weighted thickness of the bipolar plate after removing the grooves).

[0049] like Fig.12 As shown, a single cell is shown at a current density of 400 mA / cm 2 , voltage 0.6V working condition, bipolar plate width 50mm structure with different thermal conductivity and plate thickness: It can be seen from the figure that when the bipolar plate width is fixed, the thicker the bipolar plate thickness and the higher the thermal conductivity, the smaller the temperature difference of the bipolar plate plane, and as the plate thickness and thermal conductivity decrease, the temperature difference increases exponentially. When the thermal conductivity is 100W / m 2 ·K, when the bipolar plate thickness is 0.5mm, the plane temperature difference is ~5℃; when the bipolar plate thickness is 1mm, the plane temperature difference is ~3℃; when the bipolar plate thickness is 1.5mm, the plane temperature difference is ~2℃; when the bipolar plate thickness is 2mm, the plane temperature difference is ~1.5℃. For other specific parameters, see Fig.12 shown.

[0050] like Figure 6As shown, each single cell is sealed with a fluororubber coil. Since the working pressure on the circulating coolant side is relatively high, a double-channel sealing 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 other fuel and oxidant side flow channels use a common sealing groove 9. Once 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 is to prevent the coolant from entering the fuel or oxidant flow channel and damaging the fuel stack once a leak occurs on the coolant side. The working pressure on the fuel and oxidant sides is relatively small, and either a single-channel or double-channel sealing method can be used. The sealing form of the double-channel rubber coil enhances the sealing reliability of the fuel stack.

[0051] The stack of the present invention is designed with a membrane electrode main reaction zone of 300cm 2 、Current density 400mA / cm 2 _Under the working state of voltage 0.6V, 140 membrane electrodes are integrated, which can output 10kW of power supply. With the increase of the number of integrated membrane electrodes, the power will increase accordingly. Multiple stack modules can also be combined in series and parallel to form a higher power supply module; the size of the designed bipolar plate can be unconstrained. Under the current conditions of material thermal conductivity, in order to maintain an acceptable plane temperature difference in the bipolar plate, it is recommended that the bipolar plate width is less than 100mm. If the thermal conductivity of the bipolar plate material is higher, or it is lined with high thermal conductivity material, then the cooling effect will be better and the temperature difference in the single cell plane will be smaller.

[0052] Another aspect of the present invention provides an application of a fuel cell stack as described in any one of the above embodiments in the battery field.

[0053] The fuel cell stack proposed in the present invention minimizes the width of the bipolar plate, cools the side, uses heat conduction to conduct the heat out of the stack, and uses convective heat transfer in the side cooling channels to bring the heat out, circulating the heat, effectively improving the uniformity of temperature distribution inside the bipolar plate, changing the traditional design of alternating arrangement of cooling channels and reaction channels, and eliminating the coolant cavity in the stacking direction, which is beneficial to reducing the volume and weight, thereby improving the specific power of the stack.

[0054] The above description is only an embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A fuel cell stack, characterized in that: The invention comprises a stack body (7) and a first stack end plate (1) and a second stack end plate (2) respectively arranged at both ends of the stack body (7); wherein the stack body (7) has a plurality of cooling channels externally arranged at the top and bottom of the reaction zone; the upper and lower sides of the second stack end plate (2) are both provided with a circulating coolant inlet communicated with the cooling channels, and the upper and lower sides of the first stack end plate (1) are both provided with a circulating coolant outlet communicated with the cooling channels.

2. The fuel cell stack according to claim 1, characterized in that: The stack body (7) comprises N membrane electrodes and N+1 bipolar plates (6) which are alternately stacked 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; a stack anode fuel flow field (a) and a stack cathode oxidant flow field (b) are respectively provided on both side surfaces of the bipolar plate (6), and a plurality of circulating coolant flow fields for forming the cooling channel are provided on the upper and lower sides of the bipolar plate (6).

3. The fuel cell stack according to claim 2, characterized in that: Sealing grooves for installing sealing rings are arranged on the edges of the circulating coolant flow field; and a fin structure is arranged inside the circulating coolant flow field.

4. The fuel cell stack according to claim 2, characterized in that: The bipolar plate (6) is a rectangular structure, and one end of the bipolar plate (6) is provided with a stack anode fuel inlet (A) and a stack cathode oxidant outlet; the other end of the bipolar plate (6) is provided with a stack anode fuel outlet (B) and a stack cathode oxidant inlet.

5. The fuel cell stack according to claim 4, characterized in that: The stack cathode oxidant outlet comprises a first stack cathode oxidant outlet (E) and a second stack cathode oxidant outlet (F), and the first stack cathode oxidant outlet (E) and the second stack cathode oxidant outlet (F) are respectively arranged on the upper and lower sides of the stack anode fuel inlet (A); The cathode oxidant inlet of the stack includes a first cathode oxidant inlet (C) and a second cathode oxidant inlet (D), and the first cathode oxidant inlet (C) and the second cathode oxidant inlet (D) are respectively arranged on the upper and lower sides of the anode fuel outlet (B) of the stack.

6. The fuel cell stack according to claim 2, 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 single cell.

7. The fuel cell stack according to claim 1, characterized in that: The inner side surfaces of the first stack end plate (1) and the second stack end plate (2) are both provided with a plurality of circulating coolant uniform distribution plates (5), and the circulating coolant uniform distribution plates (5) respectively correspond to the plurality of cooling channels.

8. The fuel cell stack according to claim 1, characterized in that: A first insulating plate (3) and a first current collecting plate (4) are provided between the first stack end plate (1) and one end of the stack body (7); a second insulating plate (12) and a second current collecting plate (13) are provided between the second stack end plate (2) and the other end of the stack body (7); the first current collecting plate (4) and the second current collecting plate (13) are used for current input and output of the stack body (7); and the first insulating plate (3) and the second insulating plate (12) play an insulating role.

9. The fuel cell stack according to claim 1, characterized in that: The first stack end plate (1), the stack body (7) and the second stack end plate (2) are fastened together by a stack fastening strap (10).

10. Application of the fuel cell stack according to any one of claims 1 to 9 in the battery field.

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