WO2022063868A1 - Procédé de production d'une unité de pile à combustible - Google Patents

Procédé de production d'une unité de pile à combustible Download PDF

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Publication number
WO2022063868A1
WO2022063868A1 PCT/EP2021/076138 EP2021076138W WO2022063868A1 WO 2022063868 A1 WO2022063868 A1 WO 2022063868A1 EP 2021076138 W EP2021076138 W EP 2021076138W WO 2022063868 A1 WO2022063868 A1 WO 2022063868A1
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WO
WIPO (PCT)
Prior art keywords
plate
fuel cell
plates
laser beam
fuel
Prior art date
Application number
PCT/EP2021/076138
Other languages
German (de)
English (en)
Inventor
Johannes Hagen
David Thomann
Original Assignee
Robert Bosch Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Publication of WO2022063868A1 publication Critical patent/WO2022063868A1/fr

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Classifications

    • 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
    • B23K26/20—Bonding
    • B23K26/21—Bonding by welding
    • 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
    • B23K26/0624—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses using ultrashort pulses, i.e. pulses of 1ns or less
    • 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
    • B23K26/20—Bonding
    • B23K26/21—Bonding by welding
    • B23K26/22—Spot welding
    • 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
    • H01M8/0247—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the form
    • H01M8/0254—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the form corrugated or undulated
    • 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
    • H01M8/0267—Collectors; Separators, e.g. bipolar separators; Interconnectors having heating or cooling means, e.g. heaters or coolant flow channels
    • 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
    • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
    • H01M8/0286—Processes for forming seals
    • 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
    • H01M8/0297—Arrangements for joining electrodes, reservoir layers, heat exchange units or bipolar separators to each other
    • 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
    • B23K2101/006—Vehicles
    • 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 present invention relates to a method for producing a bipolar plate for a fuel cell unit according to the preamble of claim 1, a method for producing a fuel cell unit according to the preamble of claim 12 and a fuel cell unit according to the preamble of claim 15.
  • Fuel cell units as galvanic cells convert continuously supplied fuel and oxidizing agent into electrical energy by means of redox reactions at an anode and cathode.
  • Fuel cells are used in a wide variety of stationary and mobile applications, for example in houses without a connection to a power grid or in motor vehicles, in rail transport, in aviation, in space travel and in shipping. In fuel cell units, a large number of fuel cells are arranged one above the other in a stack as a stack.
  • the disk-shaped components of fuel cells are proton exchange membranes, anodes, cathodes, gas diffusion layers, and bipolar plates.
  • the electrically conductive bipolar plates are an essential part of the stack. These function as electricity collectors, for water drainage and for conducting the reaction gases and liquid or gaseous coolant through flow spaces, in particular channels or channel structures.
  • the bipolar plates rest on contact surfaces on the gas diffusion layers.
  • the bipolar plates are generally formed from two or three plates of stainless steel. During the manufacture of the bipolar plates, the plates are placed one on top of the other and then the plates are welded together so that weld seams are formed.
  • the weld seams not only have the function of connecting the plates to one another in a materially bonded and electrically conductive manner, but also serve to seal channels for coolants that are formed between two plates in a fluid-tight manner.
  • the welding processes used in this case have a low welding speed and, due to the quality of the weld seams, complex and expensive leak tests of the weld seams are also necessary.
  • a large number, for example, 400 to 500 fuel cells are arranged in a fuel cell unit.
  • the weld seams must be made to be long, so that the welding speed that can be achieved with a welding process has a significant impact on the cost of manufacturing a fuel cell unit.
  • the required tightness tests of the welds is complex, time-consuming and expensive, in particular because of the great length of the welds and the large number of fuel cells.
  • DE 102008 024478 B4 shows a method for producing a bipolar plate arrangement for a fuel cell stack, comprising the following steps: providing a first unipolar plate with a first inner surface; providing a second unipolar plate having a second interior surface;
  • Method according to the invention for producing a bipolar plate for a fuel cell unit as a fuel cell stack for the electrochemical generation of electrical energy with the steps: providing a first plate and a second plate, stacking the first plate and the second plate, producing at least one material connection as a welded connection between the first and second plates, wherein the at least one welded connection is produced by laser beam welding with a laser beam emitted by a laser, wherein the at least one welded connection is produced with a pulsed laser, in that a pulsed laser beam is emitted onto a panel by the pulsed laser.
  • the at least one welded connection can thus be produced with high speed, reliability, accuracy and tightness.
  • the at least one welded connection is formed as at least one welded seam.
  • the length of the weld is preferably 3, 5, 10, 20 or 30 times greater than the width of the weld.
  • the frequency of the pulsed laser beam is between 0.05 MHz and 20 MHz, in particular between 0.1 MHz and 10 MHz.
  • the pulse duration of the laser beam is between 0.1 ns and 500 ns, in particular between 10 ns and 200 ns.
  • the welding speed is expediently between 0.3 m/s and 10 m/s, in particular between 0.5 m/s and 5 m/s.
  • the first plate lies with an inner side on an inner side of the second plate at a contact area and the first and second plates each have an outer side opposite the inner side and the laser beam is Laser beam welding is directed to an area of an outer side of the first or second plate which is opposite to the contact area. The weld is thus made at the contact area between the first and second plates.
  • the first panel rests with a portion of the inside of the first panel on a portion of the inside of the second panel at the contact area and outside the contact area is between the insides of the first and second panel Channel for coolant formed due to the distance between the inner sides of the first and second plates in a direction perpendicular to a fictitious plane spanned by the bipolar plate.
  • the imaginary planes spanned by the first and second plates are preferably aligned essentially parallel to one another, in particular with a deviation of less than 30°, 20° or 10°.
  • the length of the coolant channel in a direction parallel to the notional plane is at least 50%, 70% or 80% of the length or width of the bipolar plate.
  • a seal for sealing the channel for coolant between the first and second plate to the outside is preferably formed by the at least one weld seam produced by laser beam welding.
  • the length of one weld seam or the sum of the lengths of the weld seams as a seal for sealing the channel for coolant between the first and second plates is at least 50%, 100%, 150% or 200% of the length of the bipolar plate one bipolar plate each.
  • the at least one welded connection, in particular at least one weld seam is produced as at least one penetration weld and/or at least one weld.
  • Method according to the invention for producing a fuel cell unit as a fuel cell stack for the electrochemical generation of electrical energy with the steps: providing layered components of fuel cells, namely proton exchange membranes, anodes, cathodes, gas diffusion layers and bipolar plates, the layered components spanning fictitious levels, arranging and/or Assembling the layered components into stacks so that fuel cells are formed and the fuel cells are stacked into a fuel cell unit, wherein the bipolar plates are provided by performing a method described in this patent application.
  • the at least one weld seam functions to seal a channel and/or a supply and/or discharge channel for coolant and/or fuel and/or oxidizing agent in a fluid-tight manner.
  • At least 90% of the bipolar plates, in particular all of the bipolar plates, are made available to the fuel cell unit by carrying out a method described in this patent application.
  • Fuel cell unit according to the invention as a fuel cell stack for the electrochemical generation of electrical energy comprising stacked fuel cells and the fuel cells each comprising stacked layered components and the components of the fuel cells are proton exchange membranes, anodes, cathodes, gas diffusion layers and bipolar plates, the fuel cell unit using a method described in this patent application is made.
  • Welds made using laser beam welding with a pulsed laser beam can be distinguished from welds made using other welding processes by examining the material of the welded joint.
  • the weld seam in particular for sealing the channel for coolant from the outside, is made of metal and/or plastic and/or composite material.
  • the at least one welded connection is designed as at least one spot welded connection.
  • the spot welding is performed, for example, by briefly directing the laser beam at a position on the outside of the first plate without relative speed, or by relatively moving the laser beam as a circle with a small diameter on the outside of the first plate.
  • a spot weld has a maximum diameter and/or a maximum extension in a direction parallel to the imaginary plane of less than 2 mm or 1 mm. Spot welds are normally only used for material connection and not as a seal.
  • first and second plates are made available at least partially, in particular completely, from metal, in particular high-grade steel and/or aluminum, and/or plastic and/or composite material.
  • the first and second plates are provided at least partially, in particular completely, in the form of waves and/or discs and/or layers.
  • a keyhole made of metal vapor and/or partially ionized metal vapor is formed in the first and/or second plate during the welding. In this way, high welding speeds can be achieved with a reliable, tight and precise formation of the welded connection only as a penetration weld or only as a weld-in.
  • the bipolar plate is formed from two or three plates and the two or three plates are connected to one another with the at least one welded connection using the method described in this patent application.
  • the at least one welded connection of the bipolar plate is produced, in particular exclusively, at the contact area.
  • the thickness of the first and second plates is between 0.01 and 1 mm, in particular between 0.03 and 0.3 mm.
  • the diameter of the spot of the laser beam on the plate is between 10 ⁇ m and 300 ⁇ m, in particular between 30 ⁇ m and 120 ⁇ m.
  • a qcw laser is used as the pulsed laser.
  • Lasers as cw lasers (continuous-wave lasers) emit light continuously and pulsed lasers do not emit light continuously, i. H. pulsed.
  • cw lasers can be operated, for example, with a modulator or chopper, so that they emit pulsed light and the cw lasers operated in this way thus form a qcw laser (quasi-continuous-wave laser).
  • the components of the fuel cells and/or the fuel cells are preferably stacked in alignment.
  • the fuel cells are stacked to form a cuboid fuel cell stack.
  • the fuel cells each comprise a proton exchange membrane, an anode, a cathode, at least one gas diffusion layer and at least one bipolar plate as components.
  • the connecting device is designed as a bolt and/or is rod-shaped.
  • the clamping elements are expediently designed as clamping plates.
  • Fuel cell system in particular for a motor vehicle, comprising a fuel cell unit as a fuel cell stack with fuel cells, a compressed gas store for storing gaseous fuel, a gas delivery device for delivering a gaseous Oxidizing agent to the cathodes of the fuel cells, wherein the fuel cell unit is designed as a fuel cell unit described in this patent application.
  • the gas conveying device is designed as a blower or a compressor.
  • the fuel cell unit comprises at least 3, 4, 5 or 6 connection devices.
  • the tensioning elements are plate-shaped and/or disc-shaped and/or flat and/or designed as a lattice.
  • the fuel is hydrogen, hydrogen rich gas, reformate gas or natural gas.
  • the fuel cells and/or the components of the fuel cells are expediently designed to be essentially flat and/or disc-shaped.
  • the oxidizing agent is air with oxygen or pure oxygen.
  • the fuel cell unit is preferably a PEM fuel cell unit with PEM fuel cells.
  • the fuel cell stack of the fuel cell unit is expediently arranged in a housing.
  • the fuel cell unit comprises a housing and/or a bearing plate and/or a connection plate.
  • the housing and in particular the bearing plate preferably delimits an interior space and the fuel cell stack is arranged within the interior space.
  • the housing is expediently fastened to the bearing plate. Openings for the introduction and/or discharge of fuel and/or oxidizing agent and/or coolant are preferably formed in the connecting plate.
  • the bearing plate also forms the connection plate, so that the bearing plate and the connection plate are formed by one component, in particular only one component.
  • the invention also includes a computer program with program code means, which are stored on a computer-readable data carrier, in order to carry out a method described in this patent application when the computer program is carried out on a computer or a corresponding computing unit.
  • the invention also includes a computer program product with program code means that are stored on a computer-readable data carrier in order to carry out a method described in this property right application when the computer program is carried out on a computer or a corresponding processing unit.
  • FIG. 1 shows a highly simplified exploded view of a fuel cell system with components of a fuel cell
  • FIG. 2 is a perspective view of part of a fuel cell
  • Fig. 4 is a perspective view of a fuel cell unit as a fuel cell stack, i. H. a fuel cell stack,
  • FIG. 5 shows a section through the fuel cell unit according to FIG. 4,
  • FIG. 6 shows a schematic perspective view of a bipolar plate
  • FIG. 8 shows a longitudinal section through a bipolar plate comprising two plates which are connected to one another with a weld seam as a full-penetration weld and also a weld is formed and
  • FIG. 9 shows a longitudinal section through a bipolar plate comprising two plates which are connected to one another with a weld seam as a weld during the welding process using a laser beam.
  • FIG. 1 to 3 show the basic structure of a fuel cell 2 as a PEM fuel cell 3 (polymer electrolyte fuel cell 3).
  • the principle of fuel cells 2 is that electrical energy or electrical current is generated by means of an electrochemical reaction.
  • Hydrogen H2 is passed as a gaseous fuel to an anode 7 and the anode 7 forms the negative pole.
  • a gaseous oxidizing agent namely air with oxygen, is fed to a cathode 8, i. H. the oxygen in the air provides the necessary gaseous oxidant.
  • a reduction acceptance of electrons takes place at the cathode 8 .
  • the oxidation as electron release is carried out at the anode 7 .
  • the difference between the normal potentials of the electrode pairs under standard conditions as a reversible fuel cell voltage or no-load voltage of the unloaded fuel cell 2 is 1.23 V. This theoretical voltage of 1.23 V is not reached in practice. In the quiescent state and with small currents, voltages of more than 1.0 V can be reached, and when operating with larger currents, voltages between 0.5 V and 1.0 V are reached.
  • the series connection of several fuel cells 2, in particular a fuel cell unit 1 as a fuel cell stack 1 of several fuel cells 2 arranged one above the other, has a higher voltage, which corresponds to the number of fuel cells 2 multiplied by the individual voltage of each fuel cell 2.
  • the fuel cell 2 also includes a proton exchange membrane 5 (proton exchange membrane, PEM), which is arranged between the anode 7 and the cathode 8 .
  • PEM proton exchange membrane
  • the anode 7 and cathode 8 are in the form of layers or discs.
  • the PEM 5 acts as an electrolyte, catalyst support and separator for the reaction gases.
  • the PEM 5 also acts as an electrical insulator and prevents an electrical short circuit between the anode 7 and cathode 8.
  • 12 ⁇ m to 150 ⁇ m thick, proton-conducting foils made from perfluorinated and sulfonated polymers are used.
  • the PEM 5 conducts the H + protons and essentially blocks ions other than H + protons, so that the charge transport can take place due to the permeability of the PEM 5 for the H + protons.
  • the PEM 5 is essentially impermeable to the reaction gases oxygen O2 and hydrogen H2, i.e. blocks the flow of oxygen O2 and hydrogen H2 between the gas space 31 at the anode 7 with fuel hydrogen H2 and the gas space 32 at the cathode 8 with air or Oxygen O2 as an oxidizing agent.
  • the proton conductivity of the PEM 5 increases with increasing temperature and increasing water content.
  • the electrodes 7 , 8 as the anode 7 and cathode 8 lie on the two sides of the PEM 5 , each facing towards the gas chambers 31 , 32 .
  • a unit made up of the PEM 5 and anode 7 and cathode 8 is referred to as a membrane electrode assembly 6 (membrane electrode assembly, MEA).
  • MEA membrane electrode assembly
  • the electrodes 6, 7 are platinum-containing carbon particles bonded to PTFE (polytetrafluoroethylene), FEP (fluorinated ethylene-propylene copolymer), PFA (perfluoroalkoxy), PVDF (polyvinylidene fluoride) and/or PVA (polyvinyl alcohol) and embedded in microporous carbon fiber, Glass fiber or plastic mats are hot-pressed.
  • a catalyst layer 30 is normally applied to each of the electrodes 6 , 7 on the side facing the gas chambers 31 , 32 .
  • the catalyst layer 30 on the gas space 31 with fuel on the anode 7 comprises nanodisperse platinum-ruthenium on graphitized soot particles which are bound to a binder.
  • the catalyst layer 30 on the gas space 32 with oxidizing agent on the cathode 8 analogously comprises nanodispersed platinum.
  • Nation® a PTFE emulsion or polyvinyl alcohol are used as binders.
  • the gas diffusion layer 9 on the anode 7 distributes the fuel from fuel channels 12 evenly onto the catalyst layer 30 on the anode 7.
  • the gas diffusion layer 9 on the cathode 8 distributes the oxidant from oxidant channels 13 evenly onto the catalyst layer 30 on the cathode 8.
  • the GDL 9 also withdraws reaction water in the reverse direction to the direction of flow of the reaction gases, i. H. in one direction each from the catalyst layer 30 to the channels 12, 13. Furthermore, the GDL 9 keeps the PEM 5 wet and conducts the current.
  • the GDL 9, for example, is made up of hydrophobic carbon paper and a bonded layer of carbon powder.
  • a bipolar plate 10 rests on the GDL 9 .
  • the electrically conductive bipolar plate 10 serves as a current collector, for water drainage and for conducting the reaction gases through a channel structure 29 and/or a flow field 29 and for dissipating the waste heat, which occurs in particular during the exothermic electrochemical reaction at the cathode 8.
  • Channels 14 for the passage of a liquid or gaseous coolant are incorporated into the bipolar plate 10 in order to dissipate the waste heat.
  • the channel structure 29 in the gas space 31 for fuel is formed by channels 12 .
  • the channel structure 29 in the gas space 32 for the oxidizing agent is formed by channels 13 .
  • Metal, conductive plastics and/or composite materials or graphite, for example, are used as the material for the bipolar plates 10 .
  • the bipolar plate 10 thus comprises the three channel structures 29 formed by the channels 12, 13 and 14 for the separate passage of fuel, oxidizing agent and coolant.
  • a fuel cell unit 1 and/or a fuel cell stack 1 and/or a fuel cell stack 1 a plurality of fuel cells 2 are arranged stacked in alignment (FIG. 4).
  • 1 shows an exploded view of two stacked fuel cells 2 .
  • An elastic seal 11 made of plastic or rubber seals the gas chambers 31, 32 in a fluid-tight manner.
  • Hydrogen H2 is stored as fuel at a pressure of, for example, 350 bar to 700 bar in a compressed gas store 21 (FIG. 1).
  • the fuel is passed through a high-pressure line 18 to a pressure reducer 20 to reduce the pressure of the fuel in a medium-pressure line 17 from approximately 10 bar to 20 bar.
  • the fuel is routed to an injector 19 from the medium-pressure line 17 .
  • the pressure of the fuel is reduced to an injection pressure of between 1 bar and 3 bar.
  • the fuel is supplied to a fuel supply line 16 (FIG. 1) and from the supply line 16 to the fuel channels 12 which form the channel structure 29 for fuel.
  • the fuel flows through the gas space 31 for the fuel.
  • the gas space 31 for the fuel is formed by the channels 12 and the GDL 9 on the anode 7 .
  • the fuel not consumed in the redox reaction at the anode 7 and any water from controlled humidification of the anode 7 are discharged from the fuel cells 2 through a discharge line 15 .
  • a gas conveying device 22 embodied for example as a fan 23 or a compressor 24, conveys air from the environment as oxidizing agent into a supply line 25 for oxidizing agent.
  • the air is supplied from the supply line 25 to the channels 13 for oxidizing agent, which form a channel structure 29 on the bipolar plates 10 for oxidizing agent, so that the oxidizing agent flows through the gas space 32 for the oxidizing agent.
  • the gas space 32 for the oxidizing agent is formed by the channels 13 and the GDL 9 on the cathode 8 .
  • a supply line 27 is used to supply coolant into the channels 14 for coolant and a discharge line 28 is used to discharge the coolant conducted through the channels 14 coolant.
  • the supply and discharge lines 15, 16, 25, 26, 27, 28 are shown in FIG. 1 as separate lines for reasons of simplification.
  • aligned fluid openings 41 on sealing plates 48 are formed in the stack of the fuel cell unit 1 as an extension on the end area 49 of the bipolar plates 10 (FIG.
  • the aligned fluid openings 41 and seals (not shown) in a direction perpendicular to the notional planes 37 between the fluid openings 41 thus form an oxidant supply channel 42, an oxidant discharge channel 43, a fuel supply channel 44, a fuel discharge channel 45, a Supply channel 46 for coolant and a discharge channel 47 for coolant.
  • the seals 11 can also be made as weld seams 59 by arranging rings (not shown) made of the same material between the end areas and connecting the rings with the end areas 49 of the bipolar plates 10 and the membrane electrode assemblies 6 are joined by laser beam welding (not shown).
  • the supply and discharge lines 15, 16, 25, 26, 27, 28 outside the stack of the fuel cell unit 1 are designed as process fluid lines.
  • the supply and discharge lines 15, 16, 25, 26, 27, 28 outside the stack of the fuel cell unit 1 open into the supply and discharge channels 42, 43, 44, 45, 46, 47 inside the stack of the fuel cell unit 1.
  • the fuel cell stack 1 together with the compressed gas reservoir 21 and the gas delivery device 22 forms a fuel cell system 4.
  • the fuel cells 2 are arranged as clamping plates 34 between two clamping elements 33 in the fuel cell unit 1 .
  • An upper clamping plate 35 lies on top fuel cell 2 and a lower clamping plate 36 lies on bottom fuel cell 2 .
  • the fuel cell unit 1 comprises approximately 200 to 500 fuel cells 2, not all of which are shown in FIG. 4 for drawing reasons.
  • the clamping elements 33 apply a compressive force to the fuel cells 2, ie the upper clamping plate 35 rests on the uppermost fuel cell 2 with a compressive force and the lower clamping plate 36 rests on the lowermost fuel cell 2 with a compressive force.
  • the fuel cell stack 2 is clamped to the tightness of the To ensure fuel, the oxidizing agent and the coolant, in particular due to the elastic seal 11, and also to keep the electrical contact resistance within the fuel cell stack 1 as small as possible.
  • four connecting devices 39 are designed as bolts 40 on the fuel cell unit 1, which are subjected to tensile stress.
  • the four bolts 40 are firmly connected to the chipboards 34 .
  • the bipolar plate 10 of the fuel cell 2 is shown.
  • the bipolar plate 10 includes the channels 12, 13 and 14 as three separate channel structures 29.
  • the channels 12, 13 and 14 are not shown separately in FIG. 6, but merely simplified as a layer of a channel structure 29.
  • FIG. 6 only one is strong Schematic representation of the bipolar plate 10 shown so that a first plate 53 and a second plate 54, from which the bipolar plate 10 is formed, are not shown separately.
  • the fluid openings 41 on the sealing plates 48 of the bipolar plates 10 and membrane electrode assemblies 6 (not shown) are arranged stacked in alignment within the fuel cell unit 1, so that supply and discharge channels 42, 43, 44, 45, 46, 47 for fuel, coolant and oxidant form.
  • the bipolar plate 10 has a length 50 and a width 51.
  • the channel 14 or the channels 14 as a channel structure 29 have a length 52 and the width of the channel structure 29 essentially corresponds, in particular with a deviation of less than 20% or 10%, to the width 51 of the bipolar plate 10.
  • the bipolar plates 10 are manufactured from the first plate 53 and the second plate 54 by laser beam welding.
  • a correspondingly corrugated first and second plate 53, 54 is placed one on top of the other and stacked, so that the inner sides 55 of the first and second plates 53, 54 lie on top of one another at strip-shaped contact areas 57 as a joint.
  • the imaginary planes 37 spanned by the disc-shaped first and second plates 53, 54 are then aligned essentially parallel to one another.
  • the first and second plates 53 , 54 made of stainless steel each have an outer side 56 opposite the inner side 55 .
  • Contact areas 57 between the inner sides 55 of the first and second plates 53, 54 strip-shaped spaces which form the channels 14 for coolant.
  • the geometry of the provided first and second plates 53, 54 with a large number of corrugations means that a large number of channels 14 are formed between the contact areas 57.
  • a laser system includes a pulsed laser 62 which emits a laser beam 63 (Fig. 9).
  • the pulsed laser 62 does not emit the laser beam 63 as bundled electromagnetic waves like a cw laser (continuous-wave laser) as a continuous wave laser, but pulsed with alternating time phases of the emission of the laser beam 63 and time phases without emitting the laser beam 63.
  • the laser beam 63 is with an optical system 64 on the outer side 56 of the first plate 53 so that the laser beam 63 impinges on the outer side 56 of the first plate 53 at a focal spot with a diameter of approximately 70 ⁇ m.
  • a movement unit either moves the laser beam 63 over the outside 56 of the first plate 53 or the first and second plates 53, 54 under the laser beam 63, so that a feed direction 67 of the laser beam 63 relative to the first and second plate 53, 54 results.
  • the laser beam 63 is absorbed by the outside 56 of the first plate 53, so that during the welding process the temperature of the stainless steel of the first and second plates 53, 54 rises above the melting temperature and a liquid melt 66 forms during the welding process, which then melts again cools and solidifies to weld joint 58 as weld seam 59.
  • a keyhole 65 optionally forms as a vapor capillary in liquid melt 66 in the beam direction of laser beam 63, which is formed as a tubular cavity made of metal vapor and/or partially ionized metal vapor below the Laser beam 63, which is moved in the feed direction 67 relative to the first and second plates 53, 54.
  • the width B (FIG. 8) of the weld seam 59 essentially corresponds to the diameter of the laser beam 63 or the focal spot.
  • the weld seam 59 is made completely continuous (shown as a continuous straight line in Fig. 6) at edge regions near the long sides of the channel structure 29 from the channels 14 for coolant and at edge regions near the broad sides of the channel structure 29 from the channels 14 for coolant facing the supply channel with one or more interruptions (shown as a dashed straight line in Fig. 6) to allow the coolant to be introduced from the coolant supply channel 46 into the channel structure 29 and from the channel structure 29 into the coolant discharge channel 47 can be discharged.
  • non-illustrated structures are formed in the bipolar plate 10 for conducting the coolant from the supply channel 46 for coolant into the channel structure 29 and from the channel structure 29 into the discharge channel 47 for coolant.
  • This weld seam 59 thus also acts as a seal to seal the channels 14 for coolant to the outside outside of the channels 14.
  • the sum of the lengths of the weld seams 59 made of metal as a seal for the coolant to the outside in each bipolar plate 10 is approximately 150% of the length 50 of the bipolar plate 10.
  • the weld seams 59 as a seal for the coolant to the outside are shown in a greatly simplified form as continuous or dashed straight lines on the channel structure 29 of the channels 12, and the actual position of the weld seams 59 as seals in the representation in Fig 6 not included.
  • additional weld seams 59 can be produced on the contact areas 57, which have no sealing function for the coolant in the environment or to the outside and only serve to bond the two plates 53, 54 and optionally also to seal between two channels 14 for coolant.
  • the process parameters of the laser beam welding of the weld seams 59 in a first exemplary embodiment are, for example, a feed rate of 0.5 m/s, a frequency of the pulsed laser beam 63 of 0.9 MHz with a pulse duration of 32 ns, a power of 250 W and a focus position of 2mm above the outside 56 of the first plate 53.
  • No shielding gas is used.
  • a protective gas for example argon, can be used, or the welding process is carried out in a vacuum at a pressure range of 1 to 100 hPa.
  • the process parameters of the laser beam welding of the weld seams 59 in a second exemplary embodiment are, for example, a feed rate of 0.75 m/s, a frequency of the pulsed laser beam 63 of 0.8 MHz with a pulse duration of 117 ns, a power of 450 W and a focus position of 1mm below the outside 56 of the first plate 53.
  • No shielding gas is used.
  • a protective gas for example argon, can optionally be used, or the welding process is carried out in a vacuum at a pressure range of 1 to 100 hPa.
  • a pulsed laser beam 63 from the pulsed laser 62 has significant advantages compared to a continuous laser beam 63 from the cw laser. Due to the pulsing of the laser beam 62, very high powers of a few 100 kW occur briefly during the pulse, so that the formation of a keyhole 65 as a vapor capillary in the liquid melt 66 is promoted. It also applies that with pulsed lasers 62, the shorter the pulse duration, the broader the spectrum of the laser beam 52 generated, in accordance with the laws of Fourier analysis.
  • the differences in the parameters of the welding process compared to a continuous laser beam 62 are due to a wide variety of physical and chemical properties of the material of the first and second plate 53, 54 means that a significantly higher welding speed than the feed speed of the laser beam 63 relative to the first plate 53 can be realized.
  • the welding process can advantageously be controlled very well by changing the parameters of the welding process, so that only penetration welds 60 or only welds 59 can be produced in a targeted and reliable manner.

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Abstract

L'invention concerne un procédé de production d'une plaque bipolaire (10) pour une unité de pile à combustible (1) en tant qu'empilement de piles à combustible pour la génération électrochimique d'énergie électrique, comprenant les étapes consistant à : fournir une première plaque (53) et une deuxième plaque (54) ; empiler la première plaque (53) et la deuxième plaque (54) ; produire au moins un joint d'un seul tenant (58) en tant que joint soudé (59) entre les première et deuxième plaques (53, 54), le ou les joints soudés (58) étant produits au moyen d'un soudage par faisceau laser au moyen d'un faisceau laser (63) émis par un laser (62), et le ou les joints soudés (59) étant produits au moyen d'un laser pulsé (62), par l'émission d'un faisceau laser pulsé (63) sur une plaque (53, 54) par le laser pulsé (62).
PCT/EP2021/076138 2020-09-25 2021-09-23 Procédé de production d'une unité de pile à combustible WO2022063868A1 (fr)

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DE102020212073.0A DE102020212073A1 (de) 2020-09-25 2020-09-25 Verfahren zur Herstellung einer Brennstoffzelleneinheit

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024022697A3 (fr) * 2022-07-27 2024-06-20 Robert Bosch Gmbh Procédé de fabrication d'une plaque bipolaire

Citations (2)

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Publication number Priority date Publication date Assignee Title
DE10221951A1 (de) * 2002-05-13 2003-12-04 Reinz Dichtungs Gmbh & Co Kg Bipolarplatte und Verfahren zu deren Herstellung
DE102008024478B4 (de) 2007-05-24 2015-12-17 GM Global Technology Operations LLC (n. d. Ges. d. Staates Delaware) Bipolarplattenanordnung, Brennstoffzellenstapel und Verfahren zum Erzeugen einer Bipolarplattenanordnung für einen Brennstoffzellenstapel

Patent Citations (2)

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Publication number Priority date Publication date Assignee Title
DE10221951A1 (de) * 2002-05-13 2003-12-04 Reinz Dichtungs Gmbh & Co Kg Bipolarplatte und Verfahren zu deren Herstellung
DE102008024478B4 (de) 2007-05-24 2015-12-17 GM Global Technology Operations LLC (n. d. Ges. d. Staates Delaware) Bipolarplattenanordnung, Brennstoffzellenstapel und Verfahren zum Erzeugen einer Bipolarplattenanordnung für einen Brennstoffzellenstapel

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Title
PENG LINFA ET AL: "Design and manufacturing of stainless steel bipolar plates for proton exchange membrane fuel cells", INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, ELSEVIER, AMSTERDAM, NL, vol. 39, no. 36, 31 October 2014 (2014-10-31), pages 21127 - 21153, XP029096601, ISSN: 0360-3199, DOI: 10.1016/J.IJHYDENE.2014.08.113 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024022697A3 (fr) * 2022-07-27 2024-06-20 Robert Bosch Gmbh Procédé de fabrication d'une plaque bipolaire

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