WO2024099413A1 - 一种阴极开放式燃料电池用超薄石墨双极板的加工方法 - Google Patents

一种阴极开放式燃料电池用超薄石墨双极板的加工方法 Download PDF

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WO2024099413A1
WO2024099413A1 PCT/CN2023/130880 CN2023130880W WO2024099413A1 WO 2024099413 A1 WO2024099413 A1 WO 2024099413A1 CN 2023130880 W CN2023130880 W CN 2023130880W WO 2024099413 A1 WO2024099413 A1 WO 2024099413A1
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Prior art keywords
graphite
bipolar plate
flow channel
plate
engraving
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PCT/CN2023/130880
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English (en)
French (fr)
Inventor
赵晨
张景然
梁松峰
董铸荣
王飞
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深圳职业技术大学
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Publication of WO2024099413A1 publication Critical patent/WO2024099413A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0213—Gas-impermeable carbon-containing materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
    • B23K26/0622—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/08—Devices involving relative movement between laser beam and workpiece
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure
    • B23K26/122—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure in a liquid, e.g. underwater
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure
    • B23K26/123—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure in an atmosphere of particular gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/362—Laser etching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/40—Removing material taking account of the properties of the material involved
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/40—Removing material taking account of the properties of the material involved
    • B23K26/402—Removing material taking account of the properties of the material involved involving non-metallic material, e.g. isolators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/70—Auxiliary operations or equipment
    • B23K26/702—Auxiliary equipment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0221—Organic resins; Organic polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0223—Composites
    • H01M8/0226—Composites in the form of mixtures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/36—Electric or electronic devices
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the invention relates to a method for processing an ultra-thin graphite bipolar plate for a cathode open fuel cell.
  • a cathode open fuel cell is a type of fuel cell. After hydrogen is introduced into the anode side, it undergoes a redox reaction with oxygen on the cathode side under the action of a catalyst to generate current, water and excess heat. This device that uses hydrogen to generate electricity is clean, zero-emission, quiet and efficient.
  • a cathode open fuel cell is different from a traditional non-open fuel cell. The cathode side of the cathode open fuel cell is directly exposed to the air and requires the use of an external fan to provide the air required for the reaction to the stack, while taking away excess heat and water.
  • the humidification and pressurization system of the oxygen on the cathode side of the fuel cell is omitted, and the original circulating water cooling system is also omitted, simplifying the device structure. Therefore, the structure of the cathode open fuel cell system is simpler and more suitable for small size, low power and high portability application scenarios.
  • the entire fuel cell system has a higher pursuit of volume power density.
  • the bipolar plate is an important component of the fuel cell, accounting for 70% of the volume of the entire stack. Therefore, under the same reaction area, the thinner the thickness, the higher the volume power density of the entire stack.
  • bipolar plates are divided into metal and graphite. Although metal is thin and has low resistance, it is difficult to manufacture. High cost and short service life. Graphite has the advantages of low manufacturing cost and long service life, but it is difficult to achieve a thinner thickness due to the processing method. This is because the current processing methods of graphite bipolar plates are mostly bare plate CNC engraving, flexible graphite plate molding or composite graphite plate hot pressing.
  • a method for processing an ultra-thin bipolar plate for an air-cooled fuel cell is provided, which is characterized by comprising:
  • laser engraving including: placing graphite light plate, laser identification and positioning, laser engraving of cathode flow channel, laser engraving of anode flow channel, laser engraving of sealing ring groove and laser engraving of opening.
  • the process parameters of laser engraving include: laser output power, spot diameter, light height, pulse frequency, scanning speed and number of scanning times.
  • an ultra-thin bipolar plate for an air-cooled fuel cell manufactured by using the above-mentioned processing method for the ultra-thin bipolar plate for an air-cooled fuel cell.
  • FIG. 1 is a schematic diagram of a processing flow of an ultra-thin graphite bipolar plate for an open cathode air-cooled fuel cell according to an embodiment of the present invention.
  • FIG. 2 is a schematic diagram of an ultra-thin graphite bipolar plate for an open cathode air-cooled fuel cell according to an embodiment of the present invention.
  • FIG. 3 is a comparison diagram of etching effects when different laser engraving media are engraved according to an embodiment of the present invention.
  • FIG. 4 is a comparison diagram of etching effects when single shot is performed for engraving using VS and not using engraving liquid according to an embodiment of the present invention.
  • an object of the present invention is to provide an ultra-thin graphite bipolar plate for an open cathode fuel cell, so as to solve the problem that the thickness of the graphite bipolar plate in the open cathode fuel cell of the prior art is not thin, resulting in low volume power density, or the mechanical strength, conductivity and drainage performance of the bipolar plate are poor after the thickness is reduced.
  • an ultra-thin graphite bipolar plate for a cathode open air-cooled fuel cell comprising:
  • an ultra-thin graphite bipolar plate for an extremely open air-cooled fuel cell with high conductivity greater than 250S/cm
  • high bending strength greater than 25Mpa
  • high compressive strength greater than 15Mpa
  • ultra-thin thickness 0.4-0.6mm
  • the graphite resin mixed composite material contains graphite particles, a conductive additive and an adhesive.
  • the graphite particles contain natural graphite, expanded graphite and One or more of artificial graphites.
  • the content of the graphite component accounts for 75%-85% of the mass of the bipolar plate.
  • the graphite particles are doped with different particle sizes, wherein the particle size less than 50um accounts for 65%-85%, and the particle size between 50mm-100um accounts for 35%-15%.
  • the conductive additive contains one or more of carbon fiber, asbestos fiber, polyester fiber or graphite fiber. According to one embodiment of the present invention, the content of the conductive additive accounts for 0.5%-1% of the mass of the bipolar plate. Further, according to one embodiment of the present invention, the length of the above-mentioned various fibers ranges from 0.07mm to 3mm.
  • the adhesive is one of epoxy resin, unsaturated polyester resin and polyphenylene sulfide resin.
  • the content of the adhesive is between 14% and 24% of the mass of the bipolar plate.
  • the composite material is blended by low temperature ball milling.
  • the grinding material is preferably a corundum can with a zirconium ball, the grinding speed is 300-500R/min (rotation), and the grinding time is 1-2 hours, so that the resin particles can be evenly coated on the surface of the graphite, the bonding effect is improved, and the conductivity is increased.
  • the mold surface is processed before the composite material is filled into the mold, including cleaning the mold cavity and spraying a release agent, wherein the release agent is one of polyethylene wax, carnauba wax, calcium stearate, and zinc stearate, so as to ensure that the graphite composite material does not adhere to the mold cavity and can be demolded smoothly.
  • a release agent is one of polyethylene wax, carnauba wax, calcium stearate, and zinc stearate
  • the process of filling the mold cavity with the composite material needs to be injected into the cavity through a specific funnel, and the thickness of the material injected into the cavity is related to the density and strength of the graphite plate after final curing.
  • the ratio of the thickness of the material injected into the cavity to the thickness of the graphite plate ranges from 20 to 25 times.
  • the compression thermosetting molding includes the processes of graphite composite material compression, exhaust and enhanced curing, wherein curing time, curing pressure and curing temperature are main control parameters and are adjusted according to the graphite composite material.
  • the graphite plate is demoulded and cooled, and the demoulding and cooling process includes the process of ejecting the graphite plate from the mold and naturally cooling it after curing.
  • the laser engraving forming process includes: graphite light plate placement, laser identification and positioning, cathode flow channel engraving, anode flow channel engraving, sealing ring groove engraving and through-port engraving.
  • the process parameters of the laser engraving process include: laser output power, spot diameter, spot height, pulse frequency, scanning speed and number of scans.
  • the laser engraving process is carried out in a nitrogen atmosphere.
  • engraving liquid is sprayed on the laser engraving path to increase the depth and etching speed of the laser engraving.
  • the engraving liquid is one of deionized water, toluene and methanol.
  • the ultra-thin graphite bipolar plate includes surface features such as a first flow channel 0, a second flow channel 04, a sealing ring groove 05, an air inlet 02, and a positioning hole 01.
  • the flow channel and the sealing ring groove among these features are engraved by a corresponding laser cutting process to achieve the desired roughness design, air flow resistance and/or hydrophobic properties.
  • the surface features such as the air inlet 02 and the positioning hole 01 are directly completed by laser cutting, wherein the pulse duration ⁇ t used is 40-60us, preferably 50us, and the peak
  • the maximum power P is 100W-200W, preferably 150W
  • the pulse frequency f is 1-3kHz, preferably 2kHz
  • the scanning speed Vs is 25 mm/s
  • the spot overlap under such irradiation conditions (the spot is formed by multiple laser sintering of a point, and the higher the overlap rate means the more uniform the sintering, and there will be no residual slag, etc.) is 93.75%, and the through hole can be cut directly.
  • the cathode flow channel 04 is an air flow channel. Because water will be generated in the flow channel, the flow channel 04 is made into a deeper form, that is, it has a high aspect ratio. Therefore, it is necessary to use a high-power, high-frequency laser engraving process to engrave the flow channel 04 so that it has a high surface roughness and excellent hydrophobic performance, improve the flow resistance in the flow channel, and extend the reaction time of the air in the flow channel.
  • the peak power P suitable for the cathode flow channel cutting is 200-300W, preferably 260W, the pulse frequency f is 1-3kHz, preferably 1.25kHz, and the scanning speed Vs is 12.5 mm/s; the maximum cutting depth obtained under this irradiation condition is 0.3mm, and the laser sintering width is 0.2mm, which can meet the high aspect ratio requirements of the cathode flow channel.
  • the anode flow channel 03 of the graphite bipolar plate is a hydrogen flow channel, and the flow channel depth is relatively shallow, 0.05mm-0.12mm, so a low-power, low-frequency laser engraving process is required to engrave the flow channel to reduce the roughness of the flow channel and reduce the flow resistance while ensuring high precision.
  • the peak power P used for the cathode flow channel cutting is 50-150W, preferably 100W
  • the pulse frequency f is 0.5-1kHz, preferably 1kHz
  • the scanning speed Vs is 25 mm/s.
  • the maximum cutting depth obtained is 0.1mm
  • the width of the laser sintering is 0.1mm, which can meet the high density ratio requirements of the anode flow channel.
  • the surface of the cathode flow channel ridge 06b and the anode flow channel ridge 06a of the graphite bipolar plate is engraved by a high-power, low-frequency laser engraving process (the bipolar plate is the fuel cell frame, in which the flow channel is concave for gas transmission, and the ridge is a convex part that plays a supporting role) to improve the surface roughness of the narrow flow channel ridge.
  • the bipolar plate and the membrane electrode assembly are assembled, the high surface roughness
  • the increased porosity of the flow channel ridges and the gas diffusion layer of the membrane electrode can improve the water and gas transmission efficiency inside the fuel cell.
  • the peak power P used in the cathode flow channel cutting is 150W-200W, preferably 180W
  • the pulse frequency f is 0.25-1kHz, preferably 0.5kHz
  • the scanning speed Vs is 5 mm/s.
  • the sealing groove 05 of the graphite bipolar plate needs to be bonded to the sealing ring in the sealing groove by an adhesive.
  • the sealing groove is shallow in depth and wide in width, so a high-power, low-frequency laser engraving process is used to engrave the sealing groove to improve the surface roughness of the sealing ring groove, which is conducive to the bonding and sealing of the adhesive and the sealing ring.
  • the peak power P used in the cathode flow channel cutting is 150W-200W, preferably 180W
  • the pulse frequency f is 0.25-1kHz, preferably 0.5kHz
  • the scanning speed Vs is 10 mm/s.
  • the present invention prepares an ultra-thin graphite plate by changing the particle size composition of the raw material formula of the bipolar plate, adopting low-temperature ball milling and hot pressing flat plate demoulding methods, and further reduces the thickness of the graphite plate while meeting the requirements of the stack assembly, thereby improving the volume power density of the stack.
  • the thickness of the molding is determined by the size of the mold; to reduce the thickness while ensuring the conductivity and strength requirements, it is necessary to improve the raw materials.
  • the present invention uses graphite powder with different particle sizes as the main raw material, and ball milling and mixing can also allow the adhesive to adhere evenly to the surface of the graphite, so that the raw materials have better contact effect during compression molding, higher uniformity, better mechanical strength and conductivity, thereby further reducing the thickness of the graphite plate.
  • the present invention uses a laser engraving method to achieve the engraving and surface shaping of characteristic structures in different regions of the fuel cell, and uses different laser parameters to change the surface morphology (roughness) of the graphite plate. Different flow resistances and wettability are formed through different roughness, thus achieving different flow resistances and wettability in different regions of the bipolar plate.
  • the design improves the internal mass transfer and heat dissipation of the fuel cell stack and increases the current density of the fuel cell stack.
  • the present invention utilizes the auxiliary effect of engraving liquid during laser engraving to infiltrate the graphite surface with the engraving liquid, accelerates the volatilization of the engraving liquid when the laser ablates the graphite surface, and utilizes the volatilization to accelerate the etching of the graphite surface, thereby making the etching effect more uniform and improving the laser engraving efficiency and accuracy.
  • bipolar plates determine the output performance, power density, service life and manufacturing cost of the battery.
  • the cathode open air-cooled fuel cell itself omits a separate cathode supply module, the cathode side of the fuel cell is directly exposed to the air, which also increases the design difficulty of the bipolar plate.
  • the present invention realizes the thickness reduction of the fuel cell bipolar plate through hot pressing and laser engraving high-precision design and processing; the cathode flow channel flow resistance is improved, the air utilization efficiency is increased, and the hydrophobic effect is improved; the anode flow channel is realized by high-precision engraving and hydrophilic design; the sealing ring groove area is engraved by array, which increases the bonding effect of the sealing ring adhesive and realizes the long-lasting and stable sealing of the low-thickness sealing ring.
  • FIG. 1 shows a method for processing an ultra-thin air-cooled fuel cell bipolar plate according to an embodiment of the present invention, which specifically includes:
  • Step 1 screening and mixing of raw materials: Graphite particles, conductive additives and adhesives are blended by low-temperature ball milling, wherein the content of graphite components accounts for 75%-85% of the mass of the bipolar plate, the conductive additive accounts for 0.5%-1% of the mass of the bipolar plate, and the content of adhesives accounts for 14%-24% of the mass of the bipolar plate.
  • the grinding material is preferably a corundum can with a zirconium ball, the grinding speed is 300-500R/min (rotation), and the grinding time is 1-2 hours.
  • the graphite particles are composed of natural graphite with a particle size of less than 50um accounting for 80% and a particle size of 50mm-100um accounting for 20%. The content of this component accounts for 20% of the mass of the bipolar plate. 80%;
  • the conductive additive is carbon fiber, the content of which accounts for 1% of the mass of the bipolar plate, and the length of the fiber ranges from 0.07mm to 3mm;
  • the adhesive is epoxy resin, which accounts for 19% of the mass of the bipolar plate
  • the grinding material is a corundum can with a zirconium ball, the grinding speed is 300R/min (rotation), and the grinding time is 2 hours, so that the resin particles are evenly coated on the graphite surface.
  • Step 2 hot pressing the graphite-resin mixed material to obtain a graphite plate with a thickness of about 0.4-0.6 mm: when the mold cavity is at room temperature, clean the cavity and apply a release agent, the release agent is one of polyethylene wax, carnauba wax, calcium stearate, and zinc stearate, then add the mold to preheat to 140°C, keep the temperature for 5 minutes, place the raw materials in the mold cavity, and the ratio of the material thickness placed in the cavity to the thickness of the graphite plate is 20-25 times, then apply pressure to close the mold, and keep it for 5 minutes, so that the graphite plate can be evenly spread over the mold cavity, and the adhesive can be repeatedly cured, finally, release the pressure to open the mold, and eject the graphite plate out of the mold cavity through the ejection device of the mold, and cool it to room temperature for use.
  • the release agent is one of polyethylene wax, carnauba wax, calcium stearate, and zinc stearate
  • the ratio of the thickness of the material put into the cavity to the thickness of the graphite plate is in the range of 20 times, and the thickness of the graphite plate in the cavity is 0.5 mm.
  • Step 3 Determine the laser processing route according to the size characteristics of the bipolar plate:
  • the laser engraving process used includes: placing the graphite plate, laser identification and positioning, cathode channel engraving, anode channel engraving, sealing ring groove engraving and port engraving. It is preferred to use the programming software provided by the laser processing equipment to set the processing parameters.
  • the laser engraving process parameters include: laser output power, spot diameter, light height, pulse frequency, scanning speed and number of scans.
  • the through-hole features such as the air inlet 02 and the positioning hole 01 are directly completed by laser cutting, wherein the pulse duration ⁇ t is 50us, the peak power P is 150W, the pulse frequency f is 2kHz, the scanning speed Vs is 25mm/s, and the spot overlap is 93.75%.
  • Cathode channel 04 is an air channel.
  • the laser peak power P used for cathode channel cutting is 260W
  • the pulse frequency f is 1.25kHz
  • the scanning speed Vs is 12.5mm/s.
  • the maximum cutting depth obtained is 0.3mm
  • the laser sintering width is 0.2mm, which can meet the high aspect ratio requirements of the cathode channel.
  • the anode flow channel 03 of the graphite bipolar plate is a hydrogen flow channel.
  • the peak power P used for cathode flow channel cutting is 100W
  • the pulse frequency f is 1kHz
  • the scanning speed Vs is 25mm/s.
  • the maximum cutting depth is 0.1mm
  • the laser sintering width is 0.1mm, which can meet the high density ratio requirements of the anode flow channel.
  • the surfaces of the cathode flow channel ridge 06b and the anode flow channel ridge 06a of the graphite bipolar plate are engraved using a high-power, low-frequency laser engraving process, with a peak power P of 150W and a scanning speed Vs of 25mm/s, to increase the porosity of the ridge and the membrane electrode and improve the water and gas transmission efficiency inside the fuel cell;
  • the sealing groove 05 of the graphite bipolar plate is bonded to the sealing ring by adhesive.
  • the sealing groove is shallow (0.3mm) and wide (3-8mm), so a high-power, low-frequency laser engraving process is used to engrave the sealing groove to improve the surface roughness of the sealing ring groove and use the adhesive and the sealing ring to bond and seal.
  • the peak power P used is 150W and the scanning speed Vs is 25mm/s.
  • Step 4 Spray engraving liquid on the graphite plate and perform laser engraving on different areas of the bipolar plate:
  • the laser ablation of the graphite surface will also accelerate the volatilization of the engraving liquid.
  • the volatilization will accelerate the etching of the graphite surface and make the etching effect more uniform, thereby improving the efficiency and accuracy of laser engraving.
  • Deionized water is selected as the engraving liquid; the left part of FIG3 is an example of not using engraving liquid as a comparative example, and the situation of the embodiment of the present invention is shown in the right part of FIG3; FIG3 is a morphological change of the sample after cutting photographed by a 3D profiler, wherein the part indicated by the reference numeral 07 is an example diagram of the comparative sample engraved without using engraving liquid, and the part indicated by the reference numeral 08 is an example diagram of the sample laser engraved using ionized water medium according to an embodiment of the present invention.
  • the continuity of the laser engraving of the embodiment of the present invention using the engraving liquid is better, and the depth and etching speed of the laser engraving can be deepened, that is, as shown in the right part of FIG3, no obvious crater morphology appears on the sample of the present invention using the engraving liquid, indicating that the laser also has an etching effect around the single point of the engraving liquid, and the engraving effect is better, thereby increasing the depth and etching speed of the laser engraving.
  • the engraving depth comparison of the embodiment of the present invention and the comparative example is shown in FIG4, and the shooting method of the picture of FIG4 is to use a 3D profiler to shoot the cross section of the graphite after low-temperature brittle fracture after being immersed in liquid nitrogen.
  • Step 5 After engraving is completed, use alcohol and deionized water to clean the surface of the bipolar plate;
  • Step 6 Dry the bipolar plate, perform glue curing on the sealing ring, and finally obtain a graphite bipolar plate with double-sided sealing rings.
  • Step 7 Testing the performance of the bipolar plate.
  • the test results of a sample according to an embodiment of the present invention are shown in Table 1.

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Abstract

一种阴极开放式燃料电池用超薄石墨双极板的加工方法。将包含不同粒径的石墨颗粒、导电助剂和粘接剂的复合材料通过模具热压制备厚度在0.4-0.6mm的石墨光板，然后通过激光雕刻技术，对石墨光板的表面进行雕刻，完成石墨双极板流道、密封槽和过渡区的加工。拥有加工速度快、精度高和成本低的特点，能够在确保双极板具有高强度、高电导率和厚度薄的特性下，同时具备适配于阴极开放式空冷燃料电池的表面形貌和流阻特性，实现燃料电池双极板流道参数、表面粗糙度、疏水性和粘接贴合度的可控性。

Description

一种阴极开放式燃料电池用超薄石墨双极板的加工方法
相关申请的交叉引用
本申请要求于2022年11月13日提交中国专利局的申请号为202211416600.7、名称为一种阴极开放式燃料电池用超薄石墨双极板的加工方法的中国专利申请的优先权,其全部内容通过引用结合在本申请中。
技术领域
本发明涉及一种阴极开放式燃料电池用超薄石墨双极板的加工方法。
背景技术
阴极开放式燃料电池是燃料电池的一种，都是在阳极侧通入氢气后，在催化剂的作用下与阴极侧的氧气发生氧化还原反应，产生电流、水和多余的热量，这种利用氢能发电的装置具有清洁、零排放、安静和高效的特点。特别是阴极开放式燃料电池，与传统的非开放式燃料电池不同，阴极开放式燃料电池的阴极侧直接暴露在空气当中，需要借助外部的风扇为电堆提供反应所需的空气，同时带走多余的热量和水，省略了燃料电池的阴极侧氧气的加湿、加压系统，同时也省去了原有的循环水散热系统，简化了装置结构。因此，阴极开放式燃料电池系统的结构更加简单，更加适合小体积、低功率和便携性高的应用场景。
但是，这也意味着整个燃料电池系统对于体积功率密度有着更高追求，双极板是燃料电池重要组成部分，占到了整个电堆体积的70％，所以在相同的反应面积下厚度越薄，整个电堆的体积功率密度也就越高。
目前双极板分为金属和石墨类，金属虽然厚度薄、电阻低，但是制造成 本高，使用寿命短，石墨类具有低制造成本和长寿命的优势，但是受制于加工方法很难实现较薄的厚度。这是因为目前石墨双极板的加工方法多数为光板CNC雕刻加工、柔性石墨板模压或复合石墨板热压工艺三种。首先，CNC雕刻加工过程中转头很难在厚度低于2mm的石墨板上雕刻，石墨板厚度过低容易引发板子的崩裂；其次，如中国专利CN108550864B《一种燃料电池双极板制造设备及其方法》介绍的柔性石墨板模压工艺可以直接在柔性石墨光板上模压出流道，但是厚度低于1.4mm时，固化后材料的力学强度不够，无法满足电堆的使用要求；第三，如中国专利CN108448131B《一种燃料电池复合材料双极板的加工方法》介绍的复合石墨板热压工艺，虽然实现了双极板的厚度低于1.4mm，但是当大面积热压成型时，复杂的流道结构会加大极板内部的应力，增加脱模的难度，极大降低了产品的良品率。
为了避免超薄石墨双极板在通过模具或者CNC雕刻过程中发生破碎、流道受损等问题的发生，通过激光雕刻流道的方式是新的研究重点，中国专利CN110739468A《燃料电池双极板加工方法》中就介绍了利用激光加工具有不产生机械应力、光斑直径小的特点，直接在石墨光板上激光雕刻出流道结构，但是这种方法缺乏对密封槽、通孔等过渡区域的直接加工，同时也缺乏对阴极面、阳极面的流道、脊的针对性设计，可能会存在双极板力学强度、导电性和排水性能差的问题，不能更好的发挥出激光加工的优势。
所以，为了克服阴极开放式燃料电池用石墨双极板的厚度极限的问题，有必要在满足电堆要求的前提下，通过相关的优化设计，从而实现对石墨双极板的厚度限制的突破。
发明内容
根据本发明的一个方面，提供了一种超薄空冷燃料电池用双极板的加工方法，其特征在于包括：
A)将石墨颗粒、导电助剂和粘接剂通过低温球磨混合的方法共混，其中石墨成分的含量占双极板的质量的75％-85％，导电助剂占双极板的质量的0.5％-1％，粘接剂的含量占双极板的质量的14％-24％，制成石墨-树脂混合材料；
B)热压石墨-树脂混合材料，获得厚度在0.4-0.6mm左右的石墨光板；
C)利用激光雕刻进行成型，包括：放置石墨光板、进行激光识别定位、进行阴极流道的激光雕刻、进行阳极流道的激光雕刻、进行密封圈凹槽的激光雕刻和通口的激光雕刻，激光雕刻的工艺参数包括：激光输出功率、光斑直径、走光高度、脉冲频率、扫描速度和扫描次数，
其中，在进行各区域的激光雕刻之前在双极板的相应区域喷涂雕刻液体，通过雕刻液体沁润在双极板表面时，激光烧蚀双极板表面时加速雕刻液体的挥发，挥发加速石墨表面的刻蚀，并使得刻蚀的效果更加的均匀，从而提高激光雕刻效率和精度。
根据本发明的一个进一步的方面，提供了采用上述的超薄空冷燃料电池用双极板的加工方法制备的超薄空冷燃料电池用双极板。
附图说明
图1为根据本发明的一个实施例的阴极开放式空冷燃料电池用超薄石墨双极板的加工流程示意图。
图2为根据本发明的一个实施例的阴极开放式空冷燃料电池用超薄石墨双极板的示意图。
图3为根据本发明的一个实施实例的不同激光雕刻介质雕刻时的刻蚀效果对比图。
图4为根据本发明的一个实施例的单次点射采用VS不采用雕刻液体进行雕刻时的刻蚀效果的对比图。
具体实施方式
针对现有技术的前述问题，本发明的一个目的是提供一种阴极开放式燃料电池用超薄石墨双极板，以解决现有技术开放式阴极燃料电池中石墨双极板厚度不薄导致体积功率密度低，或者厚度降低后双极板力学强度、导电性和排水性能差的问题。
如图1和图2所示，在根据本发明的一个实施例中，提供了一种阴极开放式空冷燃料电池用超薄石墨双极板，包括：
以石墨树脂混合的复合材料为原料，通过球磨混合、高温高压压铸成型得到厚度0.4-0.6mm的石墨光板，
通过以不同激光雕刻参数分别对双极板的阴极流道04、阳极流道03、密封圈凹槽05和通孔02进行加工，得到高电导率(大于250S/cm)、高抗弯强度(大于25Mpa)、高抗压强度(大于15Mpa)和超薄的厚度(0.4-0.6mm)的极开放式空冷燃料电池用超薄石墨双极板。
根据本发明的一个实施例，所述的石墨树脂混合的复合材料含有石墨颗粒、导电助剂和粘接剂。其中，所述的石墨颗粒含有天然石墨、膨胀石墨和 人工石墨中的一种或者多种。在根据本发明的一个实施例中，石墨成分的含量占双极板的质量的75％-85％。
根据本发明的一个实施例，所述的石墨颗粒为不同粒径掺杂组成，其中粒径尺寸小于50um的占比为65％-85％，粒径尺寸在50mm-100um的占比为35％-15％。
根据本发明的一个实施例，所述的导电助剂含有碳纤维、石棉纤维、聚酯纤维或者石墨纤维中的一种或多种。根据本发明的一个实施例，该导电助剂的含量占双极板的质量的0.5％-1％之间。进一步地，根据本发明的一个实施例，上述各种纤维的长度范围为0.07mm-3mm。
根据本发明的一个实施例，所述的粘接剂为环氧树脂、不饱和聚酯树脂、聚硫苯醚树脂类粘接剂中的一种。根据本发明的一个实施例，粘接剂的含量占双极板的质量的14％-24％之间。
根据本发明的一个实施例，所述的复合材料通过低温球磨混合的方法共混。根据本发明的一个实施例，研磨材质优选刚玉罐搭配锆球，研磨转速在300-500R/min(自转)，研磨时间为1-2小时，这样可以将树脂颗粒均匀的包覆在石墨的表面，提高粘接效果，提升电导率。
根据本发明的一个进一步的实施例，在复合材料填充模具前对模具表面进行处理，包括模腔清洁和喷涂脱模剂，所述的脱模剂为聚乙烯蜡、巴西棕榈蜡、硬脂酸钙、硬脂酸锌中的一种，这样能够保证石墨复合材料不粘连在模具腔体，顺利脱模。
所述的复合材料填充模腔的过程需要通过特定漏斗注入腔体，注入腔体的材料厚度与最终固化后石墨板密度和强度有关。在本发明的一个优选实施 例中，注入腔体的材料厚度与石墨板厚度的比值范围为20-25倍。
所述的模压热固化成型包括石墨复合材料压缩、排气和增强固化的过程，其中固化时间、固化压力和固化温度是主要控制参数，根据石墨复合材料来调整。
根据本发明的一个实施例，热压固化完成后，进行石墨光板的脱模冷却处理，所述的脱模冷却处理包括固化后石墨板顶出脱模、自然冷却的过程。
根据本发明的一个实施例，所述的激光雕刻成型过程包括：石墨光板放置、激光识别定位、阴极流道雕刻、阳极流道雕刻、密封圈凹槽雕刻和通口雕刻。
根据本发明的一个实施例，所述得激光雕刻成型过程的工艺参数包括了：激光输出功率、光斑直径、走光高度、脉冲频率、扫描速度和扫描次数。
根据本发明的一个实施例，所述的激光雕刻成型过程在氮气氛围下进行。根据本发明的一个进一步的实施例，在激光雕刻的路径上喷涂雕刻液体，以加深激光雕刻的深度和刻蚀速度。
所述的雕刻液体是去离子水、甲苯、甲醇中的一种。
如图2所示，根据本发明的一个实施例的所述超薄石墨双极板包括：第一流道0、第二流道04、密封圈凹槽05、进气口02、定位孔01等表面特征。根据本发明的一个进一步的实施例，这些特征中的流道和密封圈凹槽通过相应的激光切割工艺完成雕刻，从而实现所需的粗糙度设计、空气流阻和/或疏水特性。
根据本发明的一个实施例，所述的进气口02、定位孔01等表面特征直接通过激光切割完成，其中所用的脉冲持续时间Δt为40-60us，优选50us，峰 值功率P为100W-200W，优选150W，脉冲频率f为1-3kHz，优选2kHz，扫描速度Vs为25毫米/秒，在这种辐照条件的光斑重叠(光斑是多次激光烧结一个点形成的，重叠率越高就意味烧结的越均匀，不会残留挂渣等现象)为93.75％，可以直接将通孔切割出来。
所述的阴极流道04为空气流道，因为该流道中会产生水，所以流道04被做成较深的形式，即具有高的纵横比，所以需要采用高功率、高频次的激光雕刻工艺对流道04进行雕刻，使其具有高表面粗糙度和优异的疏水性能，提升流道内流阻，以延长空气在流道中的反应时间。所以，所述的阴极流道切割适合的峰值功率P为200-300W，优选260W，脉冲频率f为1-3kHz，优选1.25kHz，扫描速度Vs为12.5毫米/秒；在这种辐照条件所获得的最大切割深度在0.3mm,激光烧结的宽度在0.2mm,可以满足阴极流道的高纵横比要求。
根据本发明的实施例，所述的石墨双极板的阳极流道03为氢气流道，流道深度较浅，为0.05mm-0.12mm，所以需要低功率、低频次的激光雕刻工艺对流道进行雕刻，以在保证高精度的前提下，降低流道的粗糙度，减少流阻。根据本发明的具体实施例，所述的阴极流道切割采用的峰值功率P为50-150W，优选100W，脉冲频率f为0.5-1kHz，优选1kHz，扫描速度Vs为25毫米/秒，所获得的最大切割深度在0.1mm,激光烧结的宽度在0.1mm,可以满足阳极流道的高密度比要求。
根据本发明的实施例，石墨双极板的阴极流道脊06b和阳极流道脊06a的表面用高功率、低频次的激光雕刻工艺进行雕刻(双极板是燃料电池框架，其中流道是凹陷的用于气体的传输，脊为凸起的部分，起到支撑的效果)，以提升狭窄流道脊的表面粗糙度。当双极板和膜电极组装装堆时，高表面粗糙 度的流道脊与膜电极的气体扩散层的提高了的孔隙率，能够提升燃料电池内部的水、气传送效率。根据本发明的具体实施例，所述的阴极流道切割采用的峰值功率P为150W-200W,，优选180W，脉冲频率f为0.25-1kHz，优选0.5kHz，扫描速度Vs为5毫米/秒。
根据本发明的实施例，所述的石墨双极板的密封槽05需要通过粘接剂将密封圈粘接在密封槽中，密封槽的深度浅、宽度宽，所以采用高功率、低频次的激光雕刻工艺对密封槽进行雕刻，以提高密封圈凹槽的表面粗糙度，利于采用粘接剂和密封圈的粘接密封。根据本发明的具体实施例，所述的阴极流道切割采用的峰值功率P为150W-200W,，优选180W，脉冲频率f为0.25-1kHz，优选0.5kHz，扫描速度Vs为10毫米/秒。
本发明的有益效果包括：
1)本发明通过改变双极板的原材料配方粒径组成、采用低温球磨混合和热压平板脱模的方法制备了超薄石墨光板，在满足电堆组装要求的前提下，进一步降低了石墨板的厚度，提升了电堆的体积功率密度。成型的厚度由模具的尺寸来决定；在保证导电、强度要求的前提下降低厚度，就需要从原材料来改良，本发明通过使用不同粒径搭配的石墨粉为主要原料，球磨混合也可以让粘接剂均匀的黏附在石墨的表面，使得原材料压缩成型时的接触效果更好，均一性更高，力学强度和导电性更好，从而能够进一步减小石墨板的厚度。
2)本发明通过使用激光雕刻方法实现燃料电池不同区域的特征结构的雕刻和表面塑形，利用不同激光参数改变石墨板的表面形貌(粗糙度)，通过不同的粗糙度形成不同的流阻和沁润性，实现了双极板不同区域的流阻、沁润性 的设计，提高了电堆的内部传质和散热效果，提升了电堆的电流密度。
3)本发明通过在激光雕刻时利用雕刻液体的辅助作用，把雕刻液体沁润在石墨表面，在激光烧蚀石墨表面时加速雕刻液体的挥发，利用挥发加速石墨表面的刻蚀，从而使得刻蚀的效果更加均匀，提高了激光雕刻效率和精度。
双极板作为燃料电池的关键部件，决定了电池的输出性能、功率密度、使用寿命和制造成本。加之阴极开放式空冷燃料电池自身由于省去了单独的阴极供应模块，直接让燃料电池的阴极侧暴露在空气中，也加大了双极板的设计难度。因此，本发明从最初的原料体系出发，通过热压和激光雕刻高精度设计加工，实现了燃料电池双极板的厚度缩减；阴极流道流阻提高，增加空气利用效率，改善疏水效果；阳极流道实现高精度雕刻和亲水性设计；密封圈凹槽区域通过阵列雕刻，增加了密封圈粘接剂的粘接效果，实现了低厚度密封圈的持久稳定密封。
图1显示了根据本发明的一个实施例的超薄空冷燃料电池用双极板的加工方法，具体包括：
步骤1、原材料的筛选与混合：将石墨颗粒、导电助剂和粘接剂通过低温球磨混合的方法共混，其中石墨成分的含量占双极板的质量的75％-85％，导电助剂占双极板的质量的0.5％-1％，粘接剂的含量占双极板的质量的14％-24％，研磨材质优选刚玉罐搭配锆球，研磨转速在300-500R/min(自转)，研磨时间为1-2小时。
其中实施示例1中：
石墨颗粒由粒径尺寸小于50um的占比为80％，粒径尺寸在50mm-100um的占比为20％的天然石墨组成，该成分的含量占双极板的质量 的80％；
导电助剂为碳纤维，该成分的含量占双极板的质量的1％，纤维的长度范围为0.07mm-3mm；
粘接剂为环氧树脂，该成分的含量占双极板的质量的19％；
混合过程中，研磨材质为刚玉罐搭配锆球，研磨转速在300R/min(自转)，研磨时间为2小时，使树脂颗粒均匀包覆在石墨表面。
步骤2、热压石墨-树脂混合材料，获得厚度在0.4-0.6mm左右的石墨光板：在模腔常温时，清洁腔体并涂抹脱模剂，所述的脱模剂为聚乙烯蜡、巴西棕榈蜡、硬脂酸钙、硬脂酸锌中的一种，然后加入模具预热到140℃，温度保持5min后，放置原材料于模腔内，放入腔体的材料厚度与石墨板厚度的比值范围为20-25倍，然后，施加压力闭合模具，并保持5min的时间，使得石墨板能够均匀铺满模腔，粘接剂可以重复固化，最后，泄压开模，并通过模具的顶出装置将石墨光板顶出模腔，冷却至室温后备用。
其中实施示例1中：
放入腔体的材料厚度与石墨板厚度的比值范围为20倍，模腔内的石墨板厚度为0.5mm。
步骤3、根据双极板的尺寸特征，确定激光加工的路线：所采用的激光雕刻成型过程包括：放置石墨光板、进行激光识别定位、进行阴极流道雕刻、进行阳极流道雕刻、进行密封圈凹槽雕刻和通口雕刻。优选使用激光加工设备自带的编程软件对加工参数进行设置，激光雕刻的工艺参数包括：激光输出功率、光斑直径、走光高度、脉冲频率、扫描速度和扫描次数。
其中实施示例1中：
所述的进气口02、定位孔01等通孔特征直接通过激光切割完成，其中采用的脉冲持续时间Δt为50us，峰值功率P为150W，脉冲频率f为2kHz，扫描速度Vs为25mm/s，光斑重叠为93.75％。
阴极流道04为空气流道，阴极流道切割采用的激光峰值功率P为260W，脉冲频率f为1.25kHz，扫描速度Vs为12.5mm/s，在这种辐照条件所获得的最大切割深度在0.3mm,激光烧结的宽度在0.2mm,可以满足阴极流道的高纵横比要求；
石墨双极板的阳极流道03为氢气流道，阴极流道切割采用的峰值功率P为100W，脉冲频率f为1kHz，扫描速度Vs为25mm/s，在这种辐照条件的最大切割深度在0.1mm,激光烧结的宽度在0.1mm,可以满足阳极流道的高密度比要求；
石墨双极板的阴极流道脊06b和阳极流道脊06a的表面采用高功率、低频次的激光雕刻工艺进行雕刻，所用的峰值功率P为150W，扫描速度Vs为25mm/s，以提高脊与膜电极的孔隙率，提升燃料电池内部的水、气传送效率；
石墨双极板的密封槽05通过粘接剂将密封圈粘接在密封槽中，密封槽的深度浅(0.3mm)、宽度宽(3-8mm)，所以采用了高功率、低频次的激光雕刻工艺对密封槽进行雕刻，以提高密封圈凹槽的表面粗糙度，利用粘接剂和密封圈的粘接密封。所采用的峰值功率P为150W，扫描速度Vs为25mm/s。
步骤4、在石墨光板喷涂雕刻液体，对双极板不同区域进行分区激光雕刻：雕刻液体沁润在石墨表面时，激光烧蚀石墨表面时也会加速雕刻液体的挥发，挥发会加速石墨表面的刻蚀，也会使得刻蚀的效果更加的均匀，从而提高激光雕刻效率和精度。
其中实施示例1中：
选用去离子水为雕刻液体；图3的左边部分是作为对比实例的不使用雕刻液体的实例，本发明的实施例的情况如图3的右边部分所示；图3是通过3D轮廓仪拍摄的样品切割后的形貌变化，其中附图标记07所示的部分为不使用雕刻液体进行雕刻的对比样品的实例图，08所示的部分为根据本发明的一个实施例中使用离子水介质进行的激光雕刻的样品的实例图。可以看出相同雕刻工艺下，使用雕刻液体的本发明实施例的激光雕刻的连续性更好，可以加深激光雕刻的深度和刻蚀速度，即如图3中的右边部分所示，采用了雕刻液体的本发明的样品上没有出现明显的陨石坑形貌，说明激光在雕刻液体单点的周围也发生了蚀刻效果，雕刻效果更佳，从而加大激光雕刻的深度和刻蚀速度。本发明的实施例与对比例的雕刻深度对比如图4所示，图4的图片的拍摄方法为使用3D轮廓仪拍摄被液氮浸泡低温脆断后石墨截面。
步骤5、雕刻完成后，使用酒精和去离子水对双极板进行表面清洗；
步骤6、烘干双极板，进行密封圈的点胶固化，最终获得具有双面密封圈的石墨双极板。
步骤7、对双极板的性能进行测试，对根据本发明的一个实施例的样品的测试结果如表1所示。
表1

Claims (10)

  1. 一种超薄空冷燃料电池用双极板的加工方法，其特征在于包括：
    A)将石墨颗粒、导电助剂和粘接剂通过低温球磨混合的方法共混，其中石墨成分的含量占双极板的质量的75％-85％，导电助剂占双极板的质量的0.5％-1％，粘接剂的含量占双极板的质量的14％-24％，制成石墨-树脂混合材料；
    B)热压石墨-树脂混合材料，获得厚度在0.4-0.6mm左右的石墨光板；
    C)利用激光雕刻进行成型，包括：放置石墨光板、进行激光识别定位、进行阴极流道的激光雕刻、进行阳极流道的激光雕刻、进行密封圈凹槽的激光雕刻和通口的激光雕刻，激光雕刻的工艺参数包括：激光输出功率、光斑直径、走光高度、脉冲频率、扫描速度和扫描次数，
    其中，在进行各区域的激光雕刻之前在双极板的相应区域喷涂雕刻液体，通过雕刻液体沁润在双极板表面时，激光烧蚀双极板表面时加速雕刻液体的挥发，挥发加速石墨表面的刻蚀，并使得刻蚀的效果更加的均匀，从而提高激光雕刻效率和精度。
  2. 根据权利要求1所述的超薄空冷燃料电池用双极板的加工方法，其特征在于进一步包括：
    D)步骤C完成后，使用酒精和/或去离子水对双极板进行表面清洗；
    E)烘干双极板，进行密封圈的点胶固化，获得具有双面密封圈的石墨双极板。
  3. 根据权利要求1所述的超薄空冷燃料电池用双极板的加工方法，其特征在于：
    选用去离子水作为雕刻液体。
  4. 根据权利要求1所述的超薄空冷燃料电池用双极板的加工方法，其特征 在于：
    研磨材质为刚玉罐搭配锆球，研磨转速在300-500R/min，研磨时间为1-2小时，
    石墨颗粒由粒径尺寸小于50um的占比为80％，粒径尺寸在50mm-100um的占比为20％的天然石墨组成，该石墨颗粒成分的含量占双极板的质量的80％，
    导电助剂为碳纤维，该成分的含量占双极板的质量的1％，纤维的长度范围为0.07mm-3mm，
    粘接剂为环氧树脂，该成分的含量占双极板的质量的19％,
    激光雕刻的工艺参数范围包括：激光输出功率<＝300W、光斑直径<＝50um、走光高度<＝3cm、脉冲频率>＝1kHz、扫描速度>＝5mm/s和扫描次数>＝5次。
  5. 根据权利要求1所述的超薄空冷燃料电池用双极板的加工方法，其特征在于：
    步骤B包括：
    在模腔常温时，清洁腔体并涂抹脱模剂，
    所述的脱模剂为聚乙烯蜡、巴西棕榈蜡、硬脂酸钙、硬脂酸锌中的一种，模具预热到140℃，温度保持5min后，放置原材料于模腔内，放入腔体的材料厚度与石墨板厚度的比值范围为20-25倍，然后，施加压力闭合模具，并保持5min的时间，使得石墨板能够均匀铺满模腔，
    最后，泄压开模，通过模具的顶出装置将石墨光板顶出模腔，冷却至室温，
    步骤C中：
    激光雕刻过程在氮气氛围下进行，
    阴极流道为空气流道，阴极流道切割采用的激光峰值功率为260W，脉冲频率为1.25kHz，扫描速度为12.5mm/s，所获得的最大切割深度在0.3mm,激光烧结的宽度在0.2mm,以满足阴极流道的高纵横比要求；
    双极板的阳极流道为氢气流道，阴极流道切割采用的峰值功率为100W，脉冲频率为1kHz，扫描速度为25mm/s，最大切割深度在0.1mm,激光烧结的宽度在0.1mm,以满足阳极流道的高密度比要求；
    双极板的阴极流道脊和阳极流道脊的表面采用的峰值功率为150W，扫描速度为25mm/s，以提高脊与膜电极的孔隙率，提升燃料电池内部的水、气传送效率；
    石墨双极板的密封槽通过粘接剂将密封圈粘接在密封槽中，密封槽的深度为0.3mm、宽度3-8mm，采用激光雕刻工艺对密封槽进行雕刻，以提高密封圈凹槽的表面粗糙度，利用粘接剂和密封圈的粘接密封，所采用的峰值功率为150W，扫描速度为25mm/s。
  6. 一种阴极开放式燃料电池超薄石墨双极板的加工方法，其特征在于包括：
    所述的超薄石墨双极板通过在0.4-0.6mm厚度的热压固化成型石墨光板上激光雕刻的方法得到的；
    所述的超薄石墨双极板包含了流道、密封圈凹槽、进气口、定位孔等表面特征，进一步的这些特征中的流道和密封圈凹槽过不同激光切割工艺完成表面雕刻实现所需的粗糙度设计、空气流阻和疏水特性；
    其中：
    所述的加工方法可以对双极板不同特征区域的表明进行粗糙度定制加工；
    所述的双极板不同特征区域主要为阴极流道、阳极流道和密封圈凹槽；
    其中：
    石墨双极板的阴极流道为空气流道，流道中会产生水，流道较深，所以需要高功率、高频次的激光雕刻工艺对流道进行雕刻，使其具有高表面粗糙度和优异的疏水性能，提升流道内流阻，延长空气在流道中的反应时间；
    石墨双极板的阳极流道为氢气流道，流道深度较浅，所以需要低功率、低频次的激光雕刻工艺对流道进行雕刻，可以在保证高精度的前提下，降低流道的粗糙度，减少流阻；
    石墨双极板的密封槽需要通过粘接剂将密封圈粘接在密封槽中，密封槽的深度浅、宽度宽，所以需要高功率、低频次的激光雕刻工艺对密封槽进行雕刻，可以提高密封圈凹槽的表面粗糙度，利用粘接剂和密封圈的粘接密封；
    石墨双极板的阴极\阳极流道脊的表面也需要高功率、低频次的激光雕刻工艺进行雕刻，可以提升狭窄流道脊的表面粗糙度，当双极板和膜电极组装装堆时，高表面粗糙度的流道脊与膜电极的气体扩散层的孔隙率提高，提升燃料电池内部的水、气传送效率。
  7. 根据权利要求6所述得超薄石墨双极板得加工方法，其特征在于：
    所述的石墨双极板在激光雕刻前为石墨光板，该光板由石墨颗粒、导电助剂和粘接剂组成的复合材料经过高压热固的方法得到的；
    所述的石墨光板其具有大于250S/cm的电导率、(于25Mpa的抗弯强度、大于15Mpa的抗压强度和0.4-0.6mm的厚度；
    所述的石墨颗粒为天然石墨、膨胀石墨和人工石墨中的一种或者多种，所述的石墨成分的含量占双极板的质量的75％-85％；
    所述的石墨颗粒为不同粒径掺杂组成，其中粒径尺寸小于50um的占比为65％-85％，粒径尺寸在50mm-100um的占比为35％-15％；
    所述的导电助剂为碳纤维、石棉纤维、聚酯纤维或者石墨纤维中的一种或多种，该成分的含量占双极板的质量的0.5％-1％之间，进一步的纤维的长度范围为0.07mm-3mm；
    所述的粘接剂为环氧树脂、不饱和聚酯树脂、聚硫苯醚树脂类粘接剂中的一种，该成分的含量占双极板的质量的14％-24％之间。
  8. 根据权利要求6所述的超薄石墨双极板的加工方法，其特征在于：
    所述石墨双极板的加工过程为：原料混合、模具表明处理、铺料填充模腔、模压热固化成型、脱模冷却和激光雕刻成型；
    所述的原料混合过程，是将权利要求3所述的复合材料通过低温球磨混合的方法共混；
    所述的模具表明处理包括模腔清洁和喷嚏脱模剂，所述的脱模剂为聚乙烯蜡、巴西棕榈蜡、硬脂酸钙、硬脂酸锌中的一种，这样能够保证石墨复合材料不粘连在模具腔体，顺利脱模；
    所述的铺料填充模腔过程需要通过特定漏斗注入腔体，注入腔体的材料厚度与最终固化后石墨板密度和强度有关，本方法优选：注入腔体的材料厚度与石墨板厚度的比值范围为20-25倍；
    所述的模压热固化成型为石墨复合材料压缩、排气和增强固化的过程，固化时间、固化压力和固化温度是主要控制参数，根据石墨复合材料来调整；
    所述的脱模冷却即固化后石墨板顶出脱模、自然冷却的过程；
    所述的激光雕刻成型是石墨双极板的表面成型方法，热压固化的石墨板为表面光滑的平板，需要通过激光雕刻工艺完成表面形貌的雕刻塑形。
  9. 如权利要求8所述的激光雕刻成型方法，其特征在于：
    所述的激光雕刻成型过程为：石墨光板放置、激光识别定位、阴极流道 雕刻、阳极流道雕刻、密封圈凹槽雕刻和通口雕刻；
    所述得激光雕刻工艺参数包括了：激光输出功率、光斑直径、走光高度、脉冲频率、扫描速度和扫描次数；
    所述的激光雕刻过程中需要在氮气氛围下进行，同时需要在雕刻路径上喷涂雕刻液体，可以加深激光雕刻的深度和刻蚀速度；
    所述的雕刻液体是去离子水、甲苯、甲醇中的一种。
  10. 采用根据权利要求1-9之一所述的超薄空冷燃料电池用双极板的加工方法制备的超薄空冷燃料电池用双极板。
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