A fuel cell composite bipolar plate and method of assembling same

Abstract

The application belongs to the technical field of fuel cells, and particularly discloses a fuel cell composite bipolar plate and an assembling method thereof, which comprises an anode plate frame and a cathode plate frame matched with the anode plate frame, an embedded anode graphite plate is arranged on the inner ring of the anode plate frame, a first sealing ring is arranged between the anode plate frame and the embedded anode graphite plate, an embedded cathode graphite plate is arranged on the inner ring of the cathode plate frame, and a second sealing ring is arranged between the cathode plate frame and the embedded cathode graphite plate; and the anode plate frame is fixedly connected with the cathode plate frame through a buckle structure. The fuel cell composite bipolar plate and the assembling method thereof are adopted, so that good conductivity and heat conductivity are realized without being crushed, the cost is reduced, the assembly complexity is simplified, and the assembly reliability is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fuel cell technology, in particular to a fuel cell composite bipolar plate and an assembling method thereof. BACKGROUND

[0002] Fuel cell power generation is to make hydrogen, natural gas and coal gas and oxidant chemical reaction under certain conditions, to convert chemical energy directly into electrical energy. Fuel cell has the characteristics of no noise, zero pollution, large working current, high efficiency, high volume power density, good shock resistance, etc., and becomes the ideal green energy for electric vehicles. It can also be used as a portable power source for military and civilian use, and has a very broad application prospect, so it has become one of the research hotspots in the world.

[0003] The fuel cell bipolar plate is a key component of the fuel cell, which has the functions of gas separation, current collection, electrical conductivity and mechanical support. The bipolar plate not only directly affects the performance of the battery, but also accounts for 60% to 70% of the cost of the battery.

[0004] In the prior art, the bipolar plate is mainly graphite bipolar plate or metal bipolar plate, and these two kinds of bipolar plates have the following disadvantages respectively:

[0005] 1. High manufacturing cost, although the hard graphite bipolar plate has excellent electrical conductivity and heat transfer performance, the cost and processing cost of a graphite bipolar plate reaches hundreds of yuan, and the cost of processing an electric pile from hundreds of bipolar plates reaches hundreds of thousands of yuan, so that the manufactured electric pile has no competitiveness and cannot meet the commercialization demand.

[0006] 2. Insufficient strength, in order to improve the power density of the electric pile, the thickness of the graphite plate needs to be reduced, which leads to that the sealing ring becomes very thin and is easy to be crushed under the assembly pressure.

[0007] 3. Short service life, although the metal bipolar plate has the advantages of high strength and high power density (the thinnest can be 0.2mm, which greatly improves the power density of the battery), the metal bipolar plate increases the coating, which is easy to crack and fall off and oxidize (under the action of acid environment and heat of electrode reaction), and then corrosion occurs. In addition, the actual electrical conductivity and heat transfer performance of the metal bipolar plate with coating is not as good as that of the graphite plate. Therefore, the electrical conductivity is poor and easy to corrode, which often leads to short service life.

[0008] 4. Complicated assembly and positioning steps, the metal bipolar plate needs to be laser welded first and then assembled, and the graphite bipolar plate requires accurate positioning and arrangement of the sealing ring to realize leak-free assembly. SUMMARY

[0009] The fuel cell composite bipolar plate and the assembling method thereof can realize good electric conductivity and heat conductivity, enhance the strength of the bipolar plate, ensure that the bipolar plate is not crushed during assembling or use, reduce the cost, and improve the reliability of assembling and use.

[0010] To achieve the above object, the present application provides a fuel cell composite bipolar plate, comprising an anode plate frame and a cathode plate frame matched with the anode plate frame, an embedded anode graphite plate is arranged at the inner ring of the anode plate frame, a first sealing ring is arranged between the anode plate frame and the embedded anode graphite plate, an embedded cathode graphite plate is arranged at the inner ring of the cathode plate frame, and a second sealing ring is arranged between the cathode plate frame and the embedded cathode graphite plate.

[0011] The anode plate frame is fixedly connected with the cathode plate frame through a buckle structure, and a sealing ring is arranged between the anode plate frame and the cathode plate frame along the inner edge of the buckle structure.

[0012] Preferably, the buckle structure comprises a plurality of first protrusions arranged at the outer edge of the anode plate frame, a plurality of second protrusions arranged at the inner hole edge of the anode plate frame, a plurality of first grooves arranged at the outer edge of the cathode plate frame, and a plurality of second grooves arranged at the inner hole edge of the cathode plate frame, the first protrusions are connected with the first grooves in interference, and the second protrusions are connected with the second grooves in interference.

[0013] The outer edge of the anode plate frame is provided with a third groove at a position on the side of the first protrusion, the inner hole of the anode plate frame is provided with a fourth groove at a position between adjacent second protrusions, the outer edge and the inner hole of the cathode plate frame are respectively provided with third protrusions and fourth protrusions, the third protrusions are connected with the third grooves in interference, and the fourth protrusions are connected with the fourth grooves in interference.

[0014] Preferably, the overall length of the first protrusion is the same as the overall length of the first groove, the overall height of the first protrusion is the same as the depth of the first groove, and the overall height of the first protrusion is not greater than the sum of the thicknesses of the anode plate frame and the cathode plate frame.

[0015] Preferably, the outer edges of the embedded anode graphite plate and the embedded cathode graphite plate are respectively provided with strip grooves corresponding to the first sealing ring and the second sealing ring.

[0016] Preferably, the sealing ring, the first sealing ring and the second sealing ring are all made of high-temperature-resistant and acid-alkali-resistant materials.

[0017] Preferably, the sealing ring, the first sealing ring and the second sealing ring are made of silicone rubber material, and the compression rate of the silicone rubber material is 20-50%.

[0018] Preferably, the anode plate frame and the cathode plate frame are made of high and low temperature resistant acid and alkali resistant non-conductive material.

[0019] Preferably, the anode plate frame and the cathode plate frame are made of one of high and low temperature resistant acid and alkali resistant plastic, glass fiber plate and polyetherimide.

[0020] Preferably, the embedded anode graphite plate and the embedded cathode graphite plate are made of flexible or hard graphite.

[0021] The application also provides an assembling method of the fuel cell composite bipolar plate, and the steps are as follows:

[0022] The first sealing ring and the second sealing ring are respectively assembled into the strip groove of the embedded anode graphite plate and the embedded cathode graphite plate;

[0023] The embedded anode graphite plate and the embedded cathode graphite plate are respectively assembled into the inner ring of the anode plate frame and the cathode plate frame;

[0024] The sealing ring is assembled between the anode plate frame and the cathode plate frame along the position of the two side inner holes;

[0025] The anode plate frame, the gas diffusion element and the cathode plate frame are overlapped, the first protrusion, the second protrusion, the third protrusion and the fourth protrusion are buckled under pressure, the buckle type structure of mutual embedding between the first protrusion and the first groove, between the second protrusion and the second groove, between the third protrusion and the third groove and between the fourth protrusion and the fourth groove is formed, and the embedded anode graphite plate and the embedded cathode graphite plate are assembled tightly, thereby obtaining the bipolar plate.

[0026] The above steps are repeated for multiple times, and the circuit, the gas source and the water source are connected, thereby obtaining the stack.

[0027] Preferably, the first sealing ring, the second sealing ring and the sealing ring are fixed by injection molding or adhesive method.

[0028] Therefore, the fuel cell composite bipolar plate and the assembling method thereof have the following beneficial effects:

[0029] (1) The composite bipolar plate of the present application is made of graphite material or graphite composite material in the reaction area, which has good electric conductivity, high temperature resistance and corrosion resistance, and is made of non-conductive engineering plastic or composite material (such as polyetherimide material, glass fiber plate) in the non-reaction area, which increases the strength of the bipolar plate, provides good mechanical support and fixing effect, and prevents the short circuit of the anode and cathode caused by the contact of the anode and cathode frame due to misassembly.

[0030] (2) The composite bipolar plate of the present application has the characteristics of good electric conductivity of graphite bipolar plate and high strength of engineering plastic, and can prevent the crushing of the thinnest sealing ring of the bipolar plate during assembly.

[0031] (3) The anode plastic plate frame and the cathode plastic plate frame of the composite bipolar plate of the present application have a buckle structure that is misaligned with each other, which realizes good assembly positioning and fixing effect, and the buckle structure can also provide positioning for the membrane electrode assembly between the bipolar plates, ensuring the precise positioning and assembly of the bipolar plates and the membrane electrode assembly without assembly positioning and clamps, and the bipolar plates can be stacked into a whole fuel cell stack without bolt fixing.

[0032] (4) When the buckle structure is buckled with each other, the anode plastic plate frame and the cathode plastic plate frame can press the embedded anode graphite plate and the embedded cathode graphite plate together, and at the same time, the sealing ring and the sealing strip are compressed, which can realize good sealing.

[0033] The technical solutions of the present application will be further described in detail below with reference to the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a structural schematic diagram of an embodiment of the fuel cell composite bipolar plate of the present application;

[0035] Figure 2 is an exploded view of an embodiment of the fuel cell composite bipolar plate of the present application;

[0036] Figure 3 is Figure 2 the anode plate frame at A of the fuel cell composite bipolar plate of the present application;

[0037] Figure 4 is Figure 2 the cathode plate frame at B of the fuel cell composite bipolar plate of the present application;

[0038] Figure 5 is a cross-sectional view of an embodiment of the fuel cell composite bipolar plate of the present application;

[0039] Figure 6 is a partial enlarged view of the fuel cell composite bipolar plate of the present application. Figure 5

[0040] the reference signs​

[0041] 1, anode plate frame; 2, first sealing ring; 3, embedded anode graphite plate; 4, third sealing ring; 5, embedded cathode graphite plate; 6, cathode plate frame; 7, second sealing ring; 8, inner hole; 9, first protrusion; 10, second protrusion; 11, third groove; 12, fourth groove; 13, third protrusion; 14, fourth protrusion; 15, first groove; 16, second groove. DETAILED DESCRIPTION

[0042] The technical solutions of the present application are further described below by means of the accompanying drawings and examples.

[0043] Unless otherwise defined, the technical terms or scientific terms used in the present application shall have the usual meanings understood by those skilled in the art to which the present application belongs.

[0044] Example 1

[0045] As shown in the figure, a fuel cell composite bipolar plate includes an anode plate frame 1 and a cathode plate frame 6 used in pairs with the anode plate frame 1. The anode plate frame 1 and the cathode plate frame 6 are similar in structure. Taking the anode plate frame 1 as an example, the inner ring of the anode plate frame 1 is provided with an embedded anode graphite plate 3, and a first sealing ring 2 is arranged between the anode plate frame 1 and the embedded anode graphite plate 3 to avoid gaps at the contact position between the side wall of the anode plate frame 1 and the side wall of the embedded anode graphite plate 3, thereby achieving good sealing. The anode plate frame 1 is provided with a plurality of inner holes 8 at positions on both sides of the embedded anode graphite plate 3, which serve as inlets and outlets of gas flow channels or cooling liquid pipelines, and the anode plate frame 1 is provided with a flow guide channel (not marked in the figure) at a position between the inner holes 8 and the embedded anode graphite plate 3 for dispersing and guiding gas or cooling liquid.

[0046] Similarly, the inner ring of the cathode plate frame 6 is provided with the embedded cathode graphite plate 5, and the second sealing ring 7 is arranged between the cathode plate frame 6 and the embedded cathode graphite plate 5. The cross sections of the first sealing ring 2 and the second sealing ring 7 are both circular. In the embodiment, the diameters of the first sealing ring 2 and the second sealing ring 7 are 1 mm and 0.5 mm respectively, and both are made of silicone rubber material (or other commonly used high-temperature-resistant and acid-alkali-resistant materials). The outer edges of the embedded cathode graphite plate 5 and the embedded anode graphite plate 3 are respectively provided with a strip groove for placing the second sealing ring 7 or the first sealing ring 2. The diameters of the first sealing ring 2 and the second sealing ring 7 are both larger than the diameter of the strip groove, and can play a sealing role after compression installation. The first sealing ring 2, the second sealing ring 7 and the third sealing ring 4 are all made of silicone rubber material and have a compression rate greater than 20%, cooperate with the inner hole 8 and the cooling liquid guide flow channel, form a battery cooling liquid circulation loop between the embedded anode graphite plate 3 and the embedded cathode graphite plate, and realize good sealing of the battery cooling liquid circulation loop. In addition, the embedded anode graphite plate 3 and the embedded cathode graphite plate 5 are made of flexible or hard graphite, the anode plate frame 1 and the cathode plate frame 6 are made of plastic or composite material with insulation performance, high and low temperature resistance and acid and alkali resistance. In the embodiment, the high-temperature-resistant and acid-alkali-resistant plastic is PPS, which is resistant to high and low temperature, and can meet the normal operation of the fuel cell below-40℃ in the north. The embedded anode graphite plate 3 and the embedded cathode graphite plate 5 are designed to ensure excellent electrical conductivity and heat transfer performance. The anode plate frame 1 and the cathode plate frame 6 are designed to ensure the electrical conductivity of the stack, enhance the mechanical strength to meet the assembly requirements, prevent hydrogen, air and cooling liquid from mixing, and avoid the crushing phenomenon of the bipolar plate during assembly or use.

[0047] Specifically, the anode plate frame 1 is fixedly connected with the cathode plate frame 6 through a buckle type structure, the third sealing ring 4 is arranged between the anode plate frame 1 and the cathode plate frame 6, and the third sealing ring 4 is arranged along the inner edge of the buckle type structure. The cross section of the third sealing ring 4 is rectangular, and the inner hole 8 is close to the edge of the side flow guide channel without the buckle type structure. When the buckle type structures are buckled with each other, the anode plastic plate frame and the cathode plastic plate frame can press the embedded anode graphite plate 3 and the embedded cathode graphite plate 5 together, and at the same time, the third sealing ring 4, the first sealing ring 2 and the second sealing ring 7 are compressed, so that good sealing of the composite bipolar plate is realized, and hydrogen, air and cooling liquid are prevented from mixing.

[0048] As Figure 6The mechanical cross-section view shows that the sealing ring section is filled with black solid. The cathode plate and the anode plate are two plates with different thicknesses. One plate has flow fields on both sides and needs to be thicker. In this embodiment, the anode plate has flow fields on both sides, the front side is a hydrogen flow field, and the back side is a cooling liquid flow field, with a thickness of 1.2 mm. The other plate has a flow field on only one side. In this embodiment, the cathode plate has a thickness of 0.8 mm, and the back side of the anode plate is attached to the smooth surface of the cathode plate to form a closed cooling liquid flow field. The frame and the middle conductive part are provided with a groove and a sealing ring. After the anode frame and the anode middle part are assembled with the first sealing ring 2 to form a whole, the cathode frame and the cathode middle part are also assembled with the second sealing ring 7 to form a whole. After the two wholes are overlapped, a third sealing ring 4 needs to be assembled between them. This can achieve good sealing of the composite bipolar plate and prevent hydrogen, air, and cooling liquid from mixing.

[0049] Furthermore, the buckle structure includes a plurality of first protrusions 9 arranged on the outer edge of the anode plate frame 1, a plurality of second protrusions 10 arranged on the edge of the inner hole 8 of the anode plate frame 1, a plurality of first grooves 15 arranged on the outer edge of the cathode plate frame 6, and a plurality of second grooves 16 arranged on the edge of the inner hole 8 of the anode plate frame 1. The overall length of the first protrusion 9 is the same as the overall length of the first groove 15, the overall height of the first protrusion 9 is the same as the depth of the first groove 15, and the overall height of the first protrusion 9 is not greater than the sum of the thicknesses of the anode plate frame 1 and the cathode plate frame 6. The first protrusion 9 is connected with the first groove 15 in interference, so that the first protrusion 9 is embedded in the first groove 15. Similarly, the second protrusion 10 is connected with the second groove 16 in interference, and the second protrusion 10 is embedded in the second groove 16. In this embodiment, the first protrusion 9 and the second protrusion 10 are irregular geometric bodies, and the overall length refers to the longest dimension of the geometric body in the horizontal direction of the anode plate frame 1.

[0050] The third groove 11 is arranged at the outer edge of the anode plate frame 1 on one side of the first protrusion 9, the fourth groove 12 is arranged at the inner hole 8 of the anode plate frame 1 between the adjacent second protrusions 10, the third protrusion 13 and the fourth protrusion 14 are arranged at the outer edge and the inner hole 8 of the cathode plate frame 6 respectively, the third protrusion 13 is connected with the third groove 11 in interference, the fourth protrusion 14 is connected with the fourth groove 12 in interference, the third protrusion 13 is embedded in the third groove 11, the fourth protrusion 14 is embedded in the fourth groove 12, when the anode plate frame 1 and the cathode plate frame 6 are overlapped and pressed down, the bipolar plate with the buckle structure is formed under the pressure, the anode plate frame 1 and the cathode plate frame 6 can be overlapped and pressed down alternately for many times according to the design size of the electric pile, and a sealed bipolar plate is formed by cooperating with the sealing components (the third sealing ring 4, the first sealing ring 2 and the second sealing ring 7), and the electric pile is formed by installing the membrane electrode assembly between the bipolar plates; one protrusion of the outer edge of the bipolar plate is in contact with one groove, and the next protrusion and groove are spaced apart at a predetermined distance, the interval distance is appropriately increased, the assembly sealing performance and the mechanical strength meet the requirements, the processing is simplified, one protrusion of the inner hole 8 of the bipolar plate is spaced apart from one groove at a predetermined distance, and the assembly sealing performance and the mechanical strength meet the requirements.

[0051] Example two

[0052] An assembly method of a fuel cell composite bipolar plate, the steps are as follows:

[0053] (1) The first sealing ring 2 and the second sealing ring 7 are respectively assembled into the strip groove of the embedded anode graphite plate 3 and the embedded cathode graphite plate 5 by injection molding or adhesive method;

[0054] (2) The embedded anode graphite plate 3 and the embedded cathode graphite plate 5 are respectively assembled into the inner circle of the anode plate frame 1 and the cathode plate frame 6;

[0055] (3) The third sealing ring 4 is assembled between the anode plate frame 1 and the cathode plate frame 6 along the position of the inner hole 8 on both sides;

[0056] (4) The anode plate frame 1 and the cathode plate frame 6 are overlapped, the first protrusion 9 and the second protrusion 10 are buckled under pressure, the buckle structure of mutual embedding is formed between the first protrusion 9 and the first groove 15 and between the second protrusion 10 and the second groove 16, the embedded anode graphite plate 3 and the embedded cathode graphite plate 5 can be assembled tightly, and the bipolar plate is obtained;

[0057] (5) Put the membrane electrode assembly between the repeating units of the bipolar plate obtained in step (4), and also form a buckle structure by interlocking between the third protrusion 13 of the cathode plate frame 6 and the third groove 11 of the anode plate frame 1, and between the fourth protrusion 14 of the cathode plate frame 6 and the fourth groove 12 of the anode plate frame 1, to form a single cell;

[0058] (6) Repeat steps (1)-(5) multiple times to connect the circuit, gas source and cooling liquid to obtain the stack.

[0059] Test test

[0060] The bipolar plate prepared in Example 2 was subjected to plane conductivity, bending strength and helium permeability tests. The resistance tester FT-541SJB-341 was used to characterize the plane conductivity and contact resistance. The universal testing machine Instrument 3365 was used to characterize the bending strength, and the bending strength test of the composite plate was carried out by the three-point bending method according to the bipolar plate property test method (GB / T 20042.6-2024) and the impermeable graphite material bending strength test method (GB / T 13465.2). The A100 helium mass spectrometer leak detector was used to characterize the permeability. The test was repeated 3 times, and the test results are as follows:

[0061] The conductivity of the bipolar plate remained above 250 S / cm, and the interface contact resistance of the intermediate conductive area remained at 1.5 mΩ·cm 2 The bending strength reached 42 MPa, and the helium permeability was reduced to 5×10 -7 cm 3 ·cm -2 ·s -1 , indicating that the conductive performance, bending strength and air tightness all meet the standards.

[0062] Therefore, the fuel cell composite bipolar plate and the assembly method thereof are adopted to realize good conductivity and thermal conductivity while having high strength, which can ensure that the bipolar plate is not crushed during assembly or use in a vehicle, reduce costs, and improve the reliability of assembly and the reliability of the stack.

[0063] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit them, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A fuel cell composite bipolar plate, characterized by: The application relates to a bipolar plate frame structure, which comprises an anode plate frame and a cathode plate frame matched with the anode plate frame, an inner ring of the anode plate frame is provided with an embedded anode graphite plate, a first sealing ring is arranged between the anode plate frame and the embedded anode graphite plate, an inner ring of the cathode plate frame is provided with an embedded cathode graphite plate, and a second sealing ring is arranged between the cathode plate frame and the embedded cathode graphite plate. The anode plate frame is fixedly connected with the cathode plate frame through a buckle structure, and a third sealing ring is arranged between the anode plate frame and the cathode plate frame along the inner edge of the buckle structure. The buckle structure comprises a plurality of first protrusions arranged on the outer edge of the anode plate frame, a plurality of second protrusions arranged on the inner hole edge of the anode plate frame, a plurality of first grooves arranged on the outer edge of the cathode plate frame and a plurality of second grooves arranged on the inner hole edge of the cathode plate frame, the first protrusions are in interference connection with the first grooves, and the second protrusions are in interference connection with the second grooves. The outer edge of the anode plate frame is provided with a third groove on the side of the first protrusion, the inner hole of the anode plate frame is provided with a fourth groove between adjacent second protrusions, the outer edge and the inner hole of the cathode plate frame are respectively provided with third protrusions and fourth protrusions, the third protrusions are in interference connection with the third grooves, and the fourth protrusions are in interference connection with the fourth grooves.

2. A fuel cell composite bipolar plate according to claim 1, wherein: The overall length of the first protrusion is the same as the overall length of the first groove, the overall height of the first protrusion is the same as the depth of the first groove, and the overall height of the first protrusion is not greater than the sum of the thicknesses of the anode plate frame and the cathode plate frame.

3. A fuel cell composite bipolar plate according to claim 1, wherein: The outer edges of the embedded anode graphite plate and the embedded cathode graphite plate are respectively provided with strip grooves corresponding to the first sealing ring and the second sealing ring.

4. A fuel cell composite bipolar plate according to claim 3, wherein: The third sealing ring, the first sealing ring and the second sealing ring are made of high-temperature-resistant and acid-alkali-resistant materials.

5. A fuel cell composite bipolar plate according to claim 3, wherein: The third sealing ring, the first sealing ring and the second sealing ring are made of silicone rubber materials, and the compression rate of the silicone rubber materials is 20%-50%.

6. A fuel cell composite bipolar plate according to claim 1, wherein: The anode plate frame and the cathode plate frame are made of high-temperature-resistant and acid-alkali-resistant non-conductive materials.

7. A fuel cell composite bipolar plate according to claim 1, wherein: The embedded anode graphite plate and the embedded cathode graphite plate are made of flexible or hard graphite.

8. A method of assembling a fuel cell composite bipolar plate as claimed in any one of claims 1 to 7, characterised by, The steps are as follows: The first sealing ring and the second sealing ring are respectively assembled into the strip grooves of the embedded anode graphite plate and the embedded cathode graphite plate; The embedded anode graphite plate and the embedded cathode graphite plate are respectively assembled into the inner rings of the anode plate frame and the cathode plate frame; The third sealing ring is assembled between the anode plate frame and the cathode plate frame along the inner hole positions on both sides; The anode plate frame, the gas diffusion element and the cathode plate frame are overlapped, the first protrusions and the second protrusions are buckled under pressure, the buckle structure of mutual embedding is formed between the first protrusions and the first grooves and between the second protrusions and the second grooves, the embedded anode graphite plate and the embedded cathode graphite plate are tightly assembled, and a bipolar plate is obtained. The membrane electrode assembly is placed between the bipolar plate repeating units, and the third protrusion of the cathode plate frame and the third groove of the anode plate frame and the fourth protrusion of the cathode plate frame and the fourth groove of the anode plate frame are mutually embedded to form a buckle type structure, thereby forming a single cell. The above steps are repeated multiple times to connect the circuit, the gas source and the cooling liquid to obtain the stack.

9. A method of assembling a fuel cell composite bipolar plate according to claim 8, wherein: The first sealing ring, the second sealing ring and the third sealing ring are fixed by injection molding or adhesive bonding.

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