Proton exchange membrane fuel bipolar plate and cell stack manufacturing method thereof

Abstract

The invention discloses a proton exchange membrane fuel bipolar plate and a manufacturing method of a cell stack of the proton exchange membrane fuel bipolar plate, the bipolar plate is manufactured by adopting a thin metal plate stamping process and divided into a plate A and a plate B. The bipolar plate with a concave-convex flow field is formed by stamping a thin metal plate, namely, the front surface and the back surface of the plate A are respectively the anode side and the cathode side of a stack cell; and the front surface and the back surface of the plate B are respectively the anode side and the cathode side of another cell adjacent to the plate A of the electric pile. In addition, distribution plates are separately formed through stamping and are respectively welded on the distribution areas of the anode surfaces of the A and B plates through laser, the distribution plate side is the anode surface of the bipolar plate, and a sealing cavity formed by oppositely welding the distribution plates with the A and B distribution areas is a water injection cavity. A plate A, a plate B, a membrane electrode and a sealing gasket are overlapped to manufacture the proton exchange membrane fuel cell. The battery is characterized in that a unipolar plate realizes the function of a bipolar plate, an external humidifying system is not needed, the power density of a galvanic pile is high, and the system is simple to control. The sealing gaskets are attached to the plate A and the plate B, and the membrane electrode A + the membrane electrode B + the membrane electrode A + the membrane electrode B + the membrane electrode are used as battery units for lamination manufacturing.

Description

Technical Field

[0001] The invention relates to an improved technology of perfluorosulfonic acid resin proton exchange membrane fuel cell, which is suitable for manufacturing bipolar plates and proton exchange membrane fuel cells for direct water injection evaporative cooling. Background Art

[0002] The proton exchange membrane fuel cell is a power generation device that uses hydrogen as the anode, oxygen or air as the cathode, a proton exchange membrane as the electrolyte, and a bipolar plate as a reaction container and conductive component to convert chemical energy into electrical energy. While the battery is generating electricity, it also generates heat during the chemical energy conversion process due to electrochemical polarization and resistance. In order for the fuel cell to generate electricity stably and reliably, it is necessary to maintain the battery power generation state, including controlling the temperature, pressure, humidity and flow of the power generation device. This requires the design of a bipolar plate with input and output reactants, products, and electrical and thermal conductivity functions. The bipolar plate structure includes a cathode cavity, an anode cavity, and a cooling cavity. Reasonable flow fields are set in the three cavities to form reactant and product channels and coolant heat dissipation channels. The bipolar plate material includes conductive and thermal conductive materials such as graphite and metal. The heat dissipation of proton exchange membrane fuel cells is mainly achieved by the coolant on the bipolar plate contacting the bipolar plate surface. The coolant absorbs heat and carries heat to conduct the heat of the battery reaction out of the battery, controlling the battery reaction temperature and the water balance in the battery. The perfluorosulfonic acid resin proton exchange membrane must be in a hydrated state to achieve the proton conduction function, that is, the electrolyte function. This requires that the battery contains a certain amount of liquid water. The battery temperature is controlled by using a coolant to cool the battery. The water in the battery presents a fluctuating form of liquid and vapor. If there is too much liquid, the battery will be flooded, that is, the electrode is covered with water, and the diffusion of the reactants is hindered. If there is too much vapor, the battery will evaporate. The proton exchange membrane loses water, causing proton conduction obstacles. At the same time, the reactant partial pressure will also decrease, resulting in a low reactant concentration and reduced battery performance. Therefore, using a coolant to cool the battery requires complex system control capabilities to control the humidification degree of the reactants and the coolant temperature, thereby increasing the cost of this power generation device. Summary of the invention

[0003] The present invention is a bipolar plate and a battery manufactured by directly injecting water to cool the battery. The direct water injection evaporative cooling battery method is a method of directly injecting water into the anode and cathode of the battery to remove the heat of reaction by evaporation of water. This method does not require additional humidification of the reactants, and humidification of the anode and cathode reactants is achieved by direct water injection. In addition, since it is evaporative heat dissipation, the liquid water is vaporized, and the liquid water volume is inevitably reduced from the battery inlet to the outlet, and there will be no fluctuation between the liquid and vapor states. Since the phase change process of water carries a large amount of heat, the amount of water injected is much less than the coolant used in conventional bipolar plate batteries with cooling chambers. Therefore, water recovery and temperature control are simple and reliable. Therefore, the battery control system is simple. The bipolar plate and battery of the present invention are implemented in this way.

[0004] The bipolar plates are manufactured into A and B plates by stamping thin metal plates. The thin metal plates are stamped into bipolar plates with concave-convex flow fields. That is, the front and back sides of the A plate are the anode and cathode sides of the fuel cell stack respectively, and the front and back sides of the B plate are the anode and cathode sides of another fuel cell adjacent to the A plate in the stack. In addition, the distribution plates are separately stamped and laser welded to the distribution areas on the anode surfaces of the A and B plates. The side of the distribution plate is the anode surface of the bipolar plate, and the sealed cavity formed by the opposite welding of the distribution plate and the A and B distribution areas is the water injection cavity. The A and B plates are stacked with the membrane electrode and the gasket to manufacture a proton exchange membrane fuel cell. That is, the A and B plates are attached with gaskets, and "A + membrane electrode + B + membrane electrode + A + membrane electrode + B + membrane electrode" is used as the battery unit for stacking and manufacturing. The characteristics of the battery are that the single plate realizes the function of the bipolar plate, there is no external humidification system, the power density of the fuel cell stack is high, and the system control is simple.

[0005] The structures of the A and B bipolar plates both include manifolds, channels, distribution area flow fields, flow fields, and sealing frames. The manifolds and channels are the inlets and outlets of the three-fluid cavities of the bipolar plates. The manifolds of the anode and cathode cavities of the bipolar plate and the channels of the distribution area flow fields are formed by the combination of stamping channels and narrow slots, and the manifolds of the water injection cavity and the channels of the water injection cavity are stamped.

[0006] The manifolds, channels, and distribution area flow fields are stamped on the distribution plate. The stamping concave-convex direction of the distribution area flow field is opposite to that of the distribution area flow fields of the A and B plates, and the ends of the distribution area flow fields match the flow fields of the A and B plates. The manifolds of the anode and cathode cavities of the distribution plate and the channels of the distribution area flow fields are formed by the combination of stamping channels and narrow slots, and the manifolds of the water injection cavity and the channels of the water injection cavity are stamped.

[0007] The three-fluid manifolds of the distribution plate coincide with the manifolds of the A and B plates, the channels of the distribution plate match the channels of the A and B plates. The narrow slots of the channels on one side of the anode and cathode are arranged on the distribution plate, and the narrow slots of the channels on the other side are respectively arranged on the A and B plates correspondingly.

[0008] On the distribution areas on the inlet or outlet side of the A and B plates, in the same direction, that is, if the A plate selects the inlet side, then the B plate also selects the inlet side. Laser holes are punched at the ends of the distribution area flow fields, and no holes are punched on the other side; in the direction opposite to that of the A and B plates, that is, if the A and B plates select the inlet side, then the distribution plate selects the outlet side. Laser holes are punched at the ends of the flow fields of the distribution plate, and no holes are punched at the ends of the flow fields of the other side of the A and B plates corresponding to the distribution plate. The aperture of the laser holes is 10 - 200 μm, which is selected according to the hydrophilic and hydrophobic properties of the materials of the A and B plates and the distribution plate and the characteristics of the anode and cathode (the size of the micro-flow field stamping flow channel is determined according to the test results, and the theoretical calculation is not yet perfect). The water injection flow rate is controlled by the water injection pressure. The water injection pressure needs to overcome the gas pressure in the anode and cathode cavities and the micro-hole capillary force to realize water injection on the cathode and anode sides of the bipolar plate respectively.

[0009] The concave and convex parts of the flow fields of plates A and B are formed to be opposite to each other and are anti-symmetric structures. That is, for the stamping of the flow fields of plates A and B, the concave and convex directions of the stamping patterns of plate A and plate B are opposite, and the stamping parameters of the flow fields on the same side are the same. The same side refers to either the cathode side or the anode side. When plates A and B are stacked, the flow fields support each other to achieve the conductive function of the bipolar plate. The stamping patterns of the flow fields of plates A and B are the same, so that the fluid characteristics of the flow fields on the same side of plates A and B are consistent.

[0010] The flow fields of the distribution areas of plates A and B are formed in the same way, and the formations are both set to be concave. The distribution plate is welded on the distribution areas of plates A and B. The flow field of the distribution plate is opposite to the flow fields of the distribution areas of plates A and B, and the flow field of the distribution plate is set to be convex.

[0011] The concave and convex parts of the upper and lower plate surfaces of the flow fields of plates A and B are in the middle of the plate surface of the sealing frame. That is, the protruding part of the flow field is higher than the sealing frame, and the concave part of the flow field is lower than the sealing frame.

[0012] The membrane electrode structure is a stack of CCM and GDL. The corresponding functional parts include the battery active area, the distribution area and the sealing frame, which are respectively matched with the electrode plates. The battery active area is opposite to the flow field of the electrode plate, GDL is in contact with the flow field, the distribution area is opposite to the distribution area of the electrode plate, and the frame is in contact with the flow field of the distribution area. Since there is no GDL layer in the cathode and anode distribution areas, while there is a GDL layer in the flow field area of the electrode plate, the thickness of the GDL layer can be used as the increased part of the flow field depth. Therefore, the flow field depth of the distribution area is related to the GDL thickness, which is beneficial to reducing the fluid resistance of gas transportation; at the junction position between the distribution area and the flow field area, the GDL layer is biased towards the flow field side, that is, there is an appropriate distance between the GDL and the flow field of the distribution area, leaving a space for gas to enter the flow field and reducing the fluid resistance. Description of the Drawings

[0013] The following will further illustrate the above characteristics, technical features, advantages and their implementation manners of the present invention in a clear and understandable manner in combination with the drawings in the preferred embodiments.

[0014] Figure 1 Exploded front view of plate A

[0015] Figure 2 Exploded front view of plate B

[0016] Figure 3 Exploded front view of the bipolar plate sealing structure

[0017] Figure 4 Exploded front view of the battery structure

[0018] Figure 5 Stacked sectional schematic diagram of the battery structure

[0019] Figure 6 Cross-sectional view of a single cell with water injection

[0020] Figure 7 Cross-sectional view of a single cell with reaction gas entering Detailed implementation mode

[0021] The bipolar plate is manufactured into A and B plates by the stamping process of thin metal plates.

[0022] Figure 1 It is an exploded front view of the A - plate structure. Figure 2 It is an exploded front view of the B - plate structure.

[0023] The thin metal plate is stamped into a bipolar plate with concave - convex flow fields. That is, the front and back of the A - plate are the anode and cathode sides of the fuel cell stack respectively, and the front and back of the B - plate are the anode and cathode sides of another fuel cell adjacent to the A - plate in the stack. In addition, the distribution plate is separately stamped and laser - welded to the distribution areas on the anode surfaces of the A and B plates. The side of the distribution plate is the anode surface of the bipolar plate, and the sealed cavity formed by the relative welding of the distribution plate and the A and B distribution areas is the water - injection cavity. Figure 1 In (1) is the distribution plate, and (2) is the A or B plate. The A and B plates are stacked with the membrane - electrode assembly (MEA) and gaskets to manufacture a proton - exchange membrane fuel cell. That is, the A and B plates are attached with gaskets, and "A + membrane - electrode + B + membrane - electrode" is used as a battery unit for stacking. The characteristics of the battery are that the single - plate realizes the function of the bipolar plate, there is no external humidification system, the power density of the fuel cell stack is high, and the system control is simple.

[0024] Such as Figure 1 、 2 In it is the front view of the stamping of the A and B plates. The structures of the A and B bipolar plates both include manifolds (21, 22, 23), channels (210, 220, 230), distribution - area flow fields (24), flow fields (25) and sealing frames. The peripheries of the manifolds are stamped with flanges (2300) turned towards the cathode side, that is Figure 1 , the peripheries of the manifolds are stamped with flanges turned towards the back. The manifolds and channels are the three - cavity fluid inlets and outlets of the bipolar plate. The manifolds of the anode and cathode cavities of the bipolar plate and the channels of the distribution - area flow fields are formed by the combination of stamping channels (210) and narrow slits (2300), and the manifolds of the water - injection cavity and the channels of the water - injection cavity are stamped and formed. Figure 1 In (220), the distribution - area flow field (24) is stamped concave, and its upper surface is on the same plane as the sealing frame of the plate. The water - injection channel (220) is convex - dot - matrix, and the upper plane of the convex dots is on the same plane as the sealing frame. The manifolds (11, 12, 13), channels (110, 120, 130), and distribution - area flow fields (14) are stamped on the distribution plate. The peripheries of the manifolds are stamped with flanges (1300) turned towards the anode side, that is Figure 1 , the peripheries of the manifolds are stamped with flanges turned towards the upper surface. The manifolds and channels are the three - cavity fluid inlets and outlets of the bipolar plate. The manifolds of the anode and cathode cavities of the distribution plate and the channels of the distribution - area flow fields are formed by the combination of stamping channels (110) and narrow slits (1300), and the manifolds of the water - injection cavity and the channels of the water - injection cavity are stamped and formed. Figure 1(220), the flow field of the distribution area (24) is stamped convex, the bottom surface is in the same plane as the sealing frame of the distribution plate, the water injection channels (120) are in a convex dot matrix, and the upper plane of the convex points is in the same plane as the sealing frame.

[0025] Figure 1 、 Figure 2 Among them, the three-chamber manifold of the distribution plate coincides with the manifolds of plates A and B, the channels of the distribution plate match the channels of plates A and B, the narrow slits of the channels on one side of the cathode and anode are arranged on the distribution plate, and the narrow slits of the channels on the other side are respectively arranged on plates A and B correspondingly.

[0026] Figure 1 、 Figure 2 Among them, in the distribution area on the inlet or outlet side of plates A and B, in the same direction, that is, if plate A selects the inlet side, then plate B also selects the inlet side. Laser drilling (26) is used at the end of the flow field in the distribution area, and no drilling is done on the other side; in the direction opposite to plates A and B, that is, if plates A and B select the inlet side, then the distribution plate selects the outlet side. Laser drilling (16) is used at the end of the flow field of the distribution plate, and no drilling is done at the end of the flow field of the other side of plates A and B. Water injection is realized separately on the cathode and anode sides of the bipolar plate.

[0027] Figure 1 、 Figure 2 Among them, the flow fields of plates A and B are formed with convex and concave parts opposite to each other (25), which are anti-symmetric structures, that is, the flow fields of plates A and B are stamped, the stamping patterns of plate A and plate B have opposite convex and concave directions, and the stamping parameters of the flow fields on the same side are the same. The same side refers to the same cathode side or the same anode side. When plates A and B are stacked, the flow fields support each other to realize the conductive function of the bipolar plate. The stamping patterns of the flow fields of plates A and B are the same to make the fluid characteristics of the flow fields on the same side of plates A and B consistent.

[0028] The flow fields of the distribution areas of plates A and B are formed in the same way, and the formation is set to be concave. The distribution plate is welded to the distribution areas of plates A and B. See Figure 3 in (103), the flow field of the distribution plate is opposite to the flow fields of the distribution areas of plates A and B, and the flow field of the distribution plate is set to be convex.

[0029] Figure 3 、 4 Among them, the sealing frame is flat and can be processed with flanging patterns at the edges. A sealing gasket is attached to the sealing frame to isolate and seal the three chambers of the battery. The sealing gasket structure is divided into two types, one is the anode side and the other is the cathode side. The anode side sealing gasket has two thicknesses. One is around the periphery of the three-chamber manifold on the distribution plate (101), and the thickness is thinner than that of the flow field sealing gasket (102). The thickness of the cathode side sealing gasket (202) is the same. When assembling the battery, the compression rate of the sealing gasket is the same.

[0030] The convex and concave upper and lower plate surfaces of the flow fields of plates A and B are in the middle of the plate surface of the sealing frame, that is, the protruding part of the flow field is higher than the sealing frame, and the concave part of the flow field is lower than the sealing frame.

[0031] Figure 4 Among them, the membrane electrode assembly MEA is formed by laminating the FRAME and GDL. The corresponding functional parts include the battery active area, the distribution area, and the sealing frame, which respectively correspond to the electrode plates. The battery active area faces the flow field of the electrode plate, the GDL contacts the flow field, the distribution area faces the distribution area of the electrode plate, and the frame contacts the flow field of the distribution area.

[0032] Figure 5 Among them, the battery stack is formed by sequentially stacking single cells "A plate + membrane electrode" and single cells "B plate + membrane electrode" into a stack. In the figure, the upper and lower surfaces of the flow field part of the A or B plate are respectively higher and lower than the sealing frame. The gaskets (201, 202) are located on the upper and lower sides of the electrode plate frame and correspond to the membrane electrode frame (FRAME) to seal the anode and cathode chambers of the battery.

[0033] There is no GDL layer in the distribution area of the A or B plate, while the GDL layer is padded in the flow field area of the electrode plate. The thickness of the GDL layer can be used as the increased part of the flow field depth in the distribution area. Therefore, the flow field depth in the distribution area is associated with the GDL thickness. Deepening the flow field is beneficial to reducing the fluid resistance of gas transportation; at the junction of the distribution area and the flow field area, the GDL layer is biased towards the flow field side, that is, the GDL and the flow field in the distribution area are separated by an appropriate distance, leaving a space for gas to enter the flow field and reducing the fluid resistance.

[0034] Figure 6 It is a schematic diagram of direct water injection into the battery. The water injection chamber channels are stamped on the distribution plate and the water injection chamber manifold of the A or B plate near the flow field side of the distribution area. Multiple concave strip channels (120) are stamped on the flanged manifold of the distribution plate water injection chamber, and multiple convex strip channels (220) are stamped on the A or B plate. Deionized water is pumped into the water chamber manifold (12, 22), as shown in path ① in the figure, passing through channels (120) and (220), as shown in path ② in the figure, passing through the distribution plate and the distribution area (14, 24) of the A or B plate. The distribution flow fields of the distribution plate and the A or B plate intersect with each other to form a water flow channel, as shown in path ③ in the figure, and then injected into the anode flow field (25) through the distribution flow channel hole (16), as shown in path ④ in the figure. Through the purge of the reaction gas, liquid water is directly sprayed from the anode side to the GDL layer of the MEA. The water injection on the cathode side is similar to that on the anode side, and is injected into the cathode flow field (27) through the end hole (26) of the distribution area flow field of the A or B plate, achieving the purpose of the present invention.

[0035] Figure 7 It is a schematic diagram of the gas chamber channel. Multiple convex dot strip channels (210) are stamped on the anode manifold of the A or B plate near the flow field side of the distribution area, and at the flanged end (110) of the distribution plate manifold, a narrow channel opening slit (1100) is punched near the flow field side of the distribution area. Similarly, multiple concave dot strip channels (130) are stamped on the cathode manifold of the distribution plate near the flow field side of the distribution area, and at the flanged end of the cathode side manifold of the A or B plate, a side slit (2300) of the channel opening is punched near the flow field side of the distribution area (Figure 6 not shown). As Figure 6 , the anode gas is introduced into ① from the anode manifolds (11, 22), passes through the channels (110, 210) and the narrow slits (1100) on the distribution plate ②, enters the anode flow field ③, the anode gas is mixed with the water sprayed from the distribution flow channel holes (16), enters the anode reaction zone, and the object of the present invention is achieved. Similarly, the cathode gas is mixed with the water sprayed from the distribution flow channel holes (26) and enters the cathode reaction zone. The object of the water-injected bipolar plate fuel cell of the present invention is achieved.

[0036] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing specific embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the specific embodiments of the present invention.

Claims

1. The bipolar plate is manufactured by thin metal plate stamping process and divided into A and B plates. The thin metal plate is stamped to form a bipolar plate with a concave and convex flow field, that is, the front and back of the A plate are the positive and negative sides of the battery stack, respectively, and the front and back of the B plate are the positive and negative sides of the other battery stack adjacent to the A plate. In addition, the distribution plate is stamped separately and laser welded on the distribution area of ​​the anode surface of the A and B plates respectively. The side of the distribution plate is the anode surface of the bipolar plate. The sealed cavity formed by the relative welding of the distribution plate and the A and B distribution areas is the water injection cavity. The A and B plates are stacked with the membrane electrode and the sealing gasket, and the sealing gasket seals the bipolar plate air cavity to manufacture a proton exchange membrane fuel cell. That is, the A and B plates are attached with sealing gaskets, and "A+membrane electrode+B+membrane electrode+A+membrane electrode+B+membrane electrode" is stacked and manufactured as a battery unit. The battery is characterized by a single-pole plate to realize the function of a bipolar plate, no external humidification system, high power density of the battery stack, and simple system control.

2. The structures of A and B bipolar plates include manifolds, channels, distribution area flow fields, flow fields and sealing frames. The manifolds and channels are the inlet and outlet of the three-chamber fluid of the bipolar plate. The manifolds of the anode and cathode chambers of the bipolar plate and the flow field channels of the distribution area are formed by combining stamping channels and narrow slits, and the manifolds of the water injection chamber and the channels of the water injection chamber are stamped.

3. The distribution plate is stamped with manifolds, channels, and distribution area flow fields. The stamping direction of the distribution area flow field is opposite to that of the distribution area flow fields of the A and B plates. The ends of the distribution area flow fields match the flow fields of the A and B plates. The convex parts of the distribution area flow fields of the distribution plate are opposite to the flow fields of the electrode plates one by one. The manifolds of the anode and cathode chambers of the distribution plate and the flow field channels of the distribution area are formed by combining stamping channels and narrow slits, and the manifolds of the water injection chamber and the channels of the water injection chamber are stamped. The three-chamber manifold of the distribution plate coincides with the manifolds of the A and B plates, the distribution plate channels match the A and B plate channels, the narrow slits of the channels on one side of the anode and cathode are arranged on the distribution plate, and the narrow slits of the channels on the other side are arranged on the A and B plates respectively.

4. In the distribution area on the inlet or outlet side of the A and B plates, in the same direction, that is, if the A plate selects the inlet side, the B plate also selects the inlet side, and laser drilling is used at the end of the flow field of the distribution area, and no holes are drilled on the other side; in the opposite direction of the A and B plates, that is, if the A and B plates select the inlet side, the distribution plate selects the outlet side, and laser drilling is used at the end of the flow field of the distribution plate, and no holes are drilled at the end of the flow field of the distribution plate on the other side of the A and B plates. Water is injected separately on the cathode and anode sides of the bipolar plate.

5. The concave and convex parts of the flow field of plates A and B are opposite to each other and are anti-symmetric structures. That is, the flow field of plates A and B are stamped, and the stamping type of plate A and plate B are in opposite directions. The parameters of the flow field stamping on the same side are the same. The same side refers to the cathode side or the anode side. When plates A and B are superimposed, the flow fields on the back of plate A and the front of plate B support each other to achieve the conductive function of the bipolar plate. The stamping types of the flow fields of plates A and B are the same, so that the fluid characteristics of the flow fields on the same side of plates A and B are consistent.

6. The flow field forming of the distribution area of ​​A and B plates is the same, and the forming is set to be concave. The distribution plate is welded on the distribution area of ​​A and B plates. The flow field of the distribution plate is opposite to the flow field of the distribution area of ​​A and B plates, and the flow field of the distribution plate is set to be convex.

7. The concave and convex upper and lower plate surfaces of the flow field parts of plates A and B are in the middle of the sealing frame plate surface, that is, the convex part of the flow field is higher than the sealing frame, and the concave part of the flow field is lower than the sealing frame.

8. The membrane electrode structure (MEA) is a superposition of FRAME and GDL (CCM). The corresponding functional parts include the battery active area, distribution area and sealing frame, which correspond to the functional areas of the plate respectively. The battery active area is opposite to the plate flow field area, the GDL is in contact with the flow field area, the distribution area is opposite to the plate distribution area, and the frame is in contact with the distribution area flow field. Since there is no GDL layer in the anode and cathode distribution areas, and the plate flow field area is padded with a GDL layer, the GDL layer thickness can be used as a supplement to increase the depth of the distribution area flow field. At the junction of the distribution area and the flow field area, the GDL layer is biased to one side of the flow field, that is, the GDL is separated from the distribution area flow field by a suitable distance, leaving space for gas to enter the flow field and reduce fluid resistance.

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