Bipolar plate of proton exchange membrane fuel cell cooled by water injection evaporation and electric pile thereof

Abstract

The invention discloses a bipolar plate of a water injection evaporative cooling proton exchange membrane fuel cell and an electric pile thereof, the bipolar plate is manufactured by adopting a thin metal plate stamping process and is divided into a plate A and a plate B, the front surface and the back surface of the plate A are respectively a cathode side and an anode side of an electric pile cell, and the front surface and the back surface of the plate B are respectively a cathode side and an anode side of another cell adjacent to the plate A of the electric pile; the anode and cathode flow fields of the A plate and the B plate are respectively composed of a manifold, a channel, a distribution section, a water injection micropore channel and a flow field section. In addition, distribution plates are separately punched and formed, the distribution plates are welded to the anode and cathode side manifolds and the distribution sections of the polar plates through laser in a stitch mode, flow fields on the distribution plates cover the distribution sections of the polar plates and micropores of the distribution sections, and air cavity manifolds and the micropores are sealed through laser welding. A sealing cavity formed by oppositely welding the distribution plate, the A distribution area and the B distribution area is a water injection cavity. The sealing gaskets are attached to the plate A and the plate B, the battery units of A + membrane electrodes + B + membrane electrodes + A + membrane electrodes + B + membrane electrodes are adopted for lamination manufacturing, and 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.

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 coolant is used to cool the battery to control the battery temperature. The water in the battery presents a liquid and gaseous fluctuating form. If there is too much liquid, the battery will be flooded, that is, the electrode is covered with water, and the reactant diffusion is hindered. If there is too much gas, the battery will evaporate. The proton exchange membrane loses water and causes 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, the use of coolants 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 in two parts, namely Plate A and Plate B, by stamping thin metal plates. The thin metal plates are stamped into bipolar plates with concave and convex flow fields. That is, the front and back sides of Plate A are the cathode and anode sides of the fuel cell stack respectively, and the front and back sides of Plate B are the cathode and anode sides of another fuel cell adjacent to Plate A in the stack. The cathode and anode flow fields of Plate A and Plate B are respectively composed of manifolds, channels, water injection microporous channels in the distribution section, and flow field sections. Micropores are stamped at the ends of the distribution sections at the inlet and outlet, that is, at the inlet and outlet ends of the flow field. In addition, the distribution plates are separately stamped and formed, and the distribution plates are respectively laser lap-welded on the cathode and anode manifolds and distribution sections of the plates. The flow field on the distribution plates covers the distribution sections of the plates and their micropores, and the air chamber manifolds and micropores are sealed by laser welding. The sealed cavity formed by the relative welding of the distribution plates with the A and B distribution areas is the water injection cavity. The bipolar plates A and B are stacked with the membrane electrode and gaskets, and the gaskets seal the air chambers of the bipolar plates to manufacture a proton exchange membrane fuel cell. That is, gaskets are attached to the bipolar plates A and B, 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 both the bipolar plates A and B include manifolds, channels, flow fields in the distribution areas, water injection microporous channels, flow fields, and sealing frames. The manifolds and channels are the inlets and outlets of the three-chamber fluid of the bipolar plates. The manifolds of the cathode and anode chambers of the bipolar plates and the channels of the flow fields in the distribution areas are formed by the combination of stamping channels and narrow slits, and the manifolds of the water injection cavity and the channels of the water injection cavity are stamped.

[0006] The manifolds, channels, and flow fields in the distribution areas are stamped on the distribution plates. The flow fields in the distribution areas are stamped with concavity and convexity in the opposite direction to the flow fields in the distribution areas of the bipolar plates A and B, and the ends of the flow fields in the distribution areas match the flow fields of the bipolar plates A and B. The manifolds of the cathode and anode chambers of the distribution plates and the channels of the flow fields in the distribution areas are formed by the combination of stamping channels and narrow slits, and the manifolds of the water injection cavity and the channels of the water injection cavity are stamped.

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

[0008] The connection part between the distribution section and the flow field area on the bipolar plates A and B is a planar connection. The planar width corresponds to the flat plate section of the distribution plate and meets the requirements for laser welding. The inside of the welding line of the flat plate section of the plate is beneficial to the processing of the water injection microporous channels. The water injection microporous channels are stamped or laser drilled. The caliber of the microporous channels is 20 - 100 microns, and the microporous channels are processed at both the inlet section and the outlet end of the plate, so that water can be injected into the cathode and anode of the battery respectively.

[0009] The concavo-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 concavo-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 the same cathode side or the same 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] Plates A and B are divided into an inlet section and an outlet section, and the stamping of the concavo-convex parts of the flow fields in the distribution areas of the inlet section and the outlet section is in the reverse direction.

[0011] The concavo-convex parts of the flow fields of plates A and B on the upper and lower plate surfaces 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 formed by stacking 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 bipolar plates. The battery active area is opposite to the flow field of the bipolar plate, GDL is in contact with the flow field, the distribution area is opposite to the distribution area of the bipolar 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 bipolar 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.

[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 cross-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 Manner

[0021] The bipolar plates are manufactured as A and B plates by stamping thin metal plates.

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

[0023] The thin metal plates are stamped into bipolar plates with concave and 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. Additionally, the distribution plates are separately stamped and laser welded to the distribution areas on the anode and cathode surfaces of the A and B plates. The sealed cavity formed by the relative welding of the distribution plates and the A and B distribution areas is the water injection cavity. Figure 1 (1) is the distribution plate, and (2) is the A or B plate.

[0024] 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 the battery cells are stacked in the order of "A + membrane electrode + B + membrane electrode". The battery features that the single plate realizes the function of a bipolar plate, without an external humidification system, and has a high power density of the fuel cell stack and simple system control.

[0025] As shown in Figure 1 、 2 Figure 3 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 plates. The channels (210) of the manifolds and channels of the anode and cathode cavities of the bipolar plates are formed by combining stamping channels with narrow slits (2300), and the channels of the manifolds and channels of the water injection cavity are formed by stamping. Figure 1 (220). The distribution area flow field (24) is stamped concave, and its upper surface is in 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 points is in 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 plates. The channels (110) of the manifolds and channels of the anode and cathode cavities of the distribution plate are formed by combining stamping channels with narrow slits (1300), and the channels of the manifolds and channels of the water injection cavity are formed by stamping. Figure 1(220), the flow field of the distribution area (24) is stamped convex, the bottom surface is on the same plane as the sealing frame of the distribution plate, the water injection channels (120) are convex dot matrices, and the upper planes of the convex points are on the same plane as the sealing frame.

[0026] Figure 1 、 Figure 2 In it, 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 anode and cathode 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.

[0027] Figure 1 、 Figure 2 In it, in the distribution area on the inlet or outlet side of plates A and B, laser drilling (26) is used at the end of the flow field of the distribution area. The distribution plate is laser welded to the anode and cathode sides of the electrode plates respectively. Through the welding seal between the distribution plate and the electrode plates, water injection is realized on the cathode and anode sides of the bipolar plate respectively.

[0028] Figure 1 、 Figure 2 In it, the formed concave and convex parts of the flow fields of plates A and B are opposite (25), and they are anti-symmetric structures, that is, the flow fields of plates A and B are stamped, the stamping type of plate A and the stamping type of plate B have opposite concave and convex directions, and the stamping parameters of the same-side flow fields are the same. The same side means 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 types of the flow fields of plates A and B are the same, and the fluid characteristics of the same-side flow fields of plates A and B are consistent.

[0029] The forming concave and convex directions of the flow fields in the distribution areas of plates A and B. The distribution plate is welded to the anode and cathode distribution areas of plates A and B. See Figure 3 (103), the flow field of the distribution plate is opposite to the flow fields in the distribution areas of plates A and B.

[0030] Figure 3 、 4 In it, 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 structure of the sealing gasket is divided into two types, one is the anode side and the other is the cathode side. The sealing gasket on the anode side has two thicknesses. One is around the perimeter of the three-chamber manifold on the distribution plate (101), and its thickness is thinner than the flow field sealing gasket (102). The thickness of the sealing gasket on the cathode side (202) is the same. During battery assembly, the compression rate of the sealing gasket is the same.

[0031] The concave and convex upper and lower plate surfaces of the flow field parts of plates A and B (25) 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.

[0032] Figure 4In it, the membrane electrode assembly MEA is formed by laminating the FRAME and the 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.

[0033] Figure 5 In it, the battery stack is formed by stacking single cells "A plate + membrane electrode" and single cells "B plate + membrane electrode" in sequence to form a battery 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.

[0034] 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 biases 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.

[0035] Figure 6 It is a schematic diagram of direct water injection into the battery. The water injection cavity channel is stamped on the side of the distribution plate and the water injection cavity manifold of the A or B plate close to the flow field in the distribution area. Multiple concave strip channels (120) are stamped on the flanged manifold of the distribution plate water injection cavity, and multiple convex strip channels (220) are stamped on the A or B plate. Deionized water is pumped from the water cavity manifold (12, 22), as shown in path ① in the figure, through channels (120) and (220), as shown in path ② in the figure, 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 cross each other to form a water flow channel, as shown in path ③ in the figure, and then is injected into the electrode plate flow field (25) through the microporous flow channel holes (26) of the electrode plate, as shown in path ④ in the figure. Through the purge of the reaction gas, direct injection of liquid water from the anode side to the GDL layer of the MEA is realized.

[0036] Figure 7 It is a schematic diagram of the gas cavity channel. For example, multiple convex dot strip channels (210) are stamped on the side of the anode manifold of the A or B plate close to the flow field in the distribution area. At the end of the flanged manifold of the distribution plate (110), a narrow slit (1100) for the channel is punched on the side close to the flow field in the distribution area. As shown in the figure, the anode gas is introduced from the anode manifold (11, 22) ①, passes through channels (110, 210) and the narrow slit (1100) on the distribution plate ②, enters the anode flow field ③, and the anode gas is mixed with the water sprayed from the distribution flow channel holes (26) and enters the anode reaction area to achieve the purpose of the present invention.

[0037] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing specific embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the specific embodiments of the present invention.

Claims

1. The bipolar plates are manufactured as A and B plates using a thin metal plate stamping process. The thin metal plate is stamped into a bipolar plate with concave and convex flow fields. That is, the front and back of the A plate are the cathode and anode sides of the fuel cell stack respectively, and the front and back of the B plate are the cathode and anode sides of another fuel cell adjacent to the A plate in the stack. The cathode and anode flow fields of the A and B plates are each composed of a manifold, channels, a water injection microporous channel in the distribution section, and a flow field section. Micropores are stamped at the ends of the distribution sections at the inlets and outlets, i.e., the inlets and outlets of the flow field. Additionally, a distribution plate is separately stamped and formed, and the distribution plate is laser lap-welded to the cathode and anode manifolds and the distribution sections of the bipolar plates respectively. The flow field on the distribution plate covers the distribution sections of the bipolar plates and their micropores, and the air cavity manifolds and micropores are sealed by laser welding. The sealed cavity formed by the relative welding of the distribution plate with the A and B distribution areas is the water injection cavity. The A and B plates are stacked with the membrane electrode and gaskets. The gaskets seal the air cavities of the bipolar plates 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 a battery unit for stacking and manufacturing. The battery features that a single bipolar plate realizes the function of a bipolar plate, there is no external humidification system, the fuel cell stack has a high power density, and the system control is simple 。 2. The bipolar plate structures of A and B both include manifolds, channels, flow fields in the distribution areas, water injection microporous channels, flow fields, and sealing frames. The manifolds and channels are the three-chamber fluid inlets and outlets of the bipolar plates. The manifolds of the anode and cathode chambers of the bipolar plates and the channels of the flow fields in the distribution areas are formed by the combination of stamping channels and narrow slits, and the manifolds of the water injection chamber and the channels of the water injection chamber are formed by stamping.

3. The manifolds, channels, and flow fields in the distribution areas are stamped on the distribution plate. The stamping convexity and concavity directions of the flow fields in the distribution areas of the distribution plate are opposite to those of the flow fields in the distribution areas of the A and B plates. The ends of the flow fields in the distribution areas are matched with the flow fields of the A and B plates. The convex parts of the flow fields in the distribution areas of the distribution plate are opposite to the flow fields of the plates one by one. The manifolds of the anode and cathode chambers of the distribution plate and the channels of the flow fields in the distribution areas are formed by the combination of stamping channels and narrow slits, and the manifolds of the water injection chamber and the channels of the water injection chamber are formed by stamping. When the distribution plate is laser welded to the plate, the distribution plate is welded to the anode and cathode sides of the plate respectively. To balance the thickness of the plate in the distribution section, a concave pit can be stamped on the cathode side or the anode plate of the plate in advance to compensate for the material thickness of the distribution plate. The three-chamber 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 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 corresponding to each other.

4. The connection part between the distribution section and the flow field area on the A and B plates is a planar connection. The planar width corresponds to the flat section of the distribution plate and meets the requirements of laser welding. The inner side of the welding line of the flat section of the plate is beneficial to the processing of the water injection microporous channels.

5. The convex and concave parts of the flow fields of the A and B plates are formed to be opposite to each other and are anti-symmetric structures, that is, the flow fields of the A and B plates are stamped. The stamping patterns of the A plate and the B plate have opposite convexity and concavity 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 the A and B plates are stacked, that is, the back of the A plate and the front of the B plate support each other in the flow field, realizing the conductive function of the bipolar plate. The stamping patterns of the flow fields of the A and B plates are the same, realizing the same fluid characteristics of the flow fields on the same side of the A and B plates.

6. The A and B plates are divided into an inlet section and an outlet section. The stamping convexity and concavity directions of the flow fields in the distribution areas of the inlet section and the outlet section are opposite.

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

8. The membrane electrode assembly (MEA) is formed by laminating FRAME and GDL (CCM). The corresponding functional parts include the battery active area, the distribution area, and the sealing frame, which correspond to the functional areas of the plate respectively. The battery active area corresponds to the flow field area of the plate, GDL contacts the flow field area, the distribution area corresponds to the distribution area of the plate, and the frame contacts the flow field in the distribution area. Since there is no GDL layer in the anode and cathode distribution areas, and there is a GDL layer padded in the flow field area of the plate, the thickness of the GDL layer can be used as a supplement to the increased part of the depth of the flow field in the distribution area. At the junction of 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 in the distribution area, leaving a space for gas to enter the flow field and reducing the fluid resistance.

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