WO2024133041A1

WO2024133041A1 - Method for producing membrane electrode assemblies for an electrochemical cell unit

Info

Publication number: WO2024133041A1
Application number: PCT/EP2023/086295
Authority: WO
Inventors: Martin Scherner; David Thomann
Original assignee: Robert Bosch Gmbh
Priority date: 2022-12-21
Filing date: 2023-12-18
Publication date: 2024-06-27
Also published as: DE102022214154A1

Abstract

The invention relates to a method for producing membrane electrode assemblies (6) comprising first and second subgaskets (62, 63, 64) and proton exchanger membranes (5) for an electrochemical cell unit (53) for converting electrochemical energy into electrical energy as a fuel cell unit (1) and/or for converting electrical energy into electrochemical energy as an electrolysis cell unit (49), comprising the following steps: making available in each case one associated proton exchanger membrane (5), making available a subgasket (62, 93), severing the subgasket (62, 93) by means of a laser beam (81) using a separating device, with the result that a first and a second subgasket (62, 63, 64) are produced, arranging the associated proton exchanger membrane (5) between the respectively associated first and second subgaskets (62, 63, 64), connecting the associated proton exchanger membrane (5) to the respectively associated first and second subgaskets (62, 63, 64) to form the membrane electrode assembly (6), wherein the subgasket (62, 93) is severed by the laser beam (81) by virtue of the fact that the laser beam (81) is directed at a primary side (84) of the subgasket (62, 93) and, during the severing, a focal spot (82) of the laser beam (81) carries out a relative movement on the primary side (84) of the subgasket (62, 93) and, simultaneously, a secondary side (85) of the subgasket (62, 93) bears on a conveying device (86) and the secondary side (85) of the subgasket (62, 93) is an opposite side of the subgasket (62, 93) with respect to the primary side (84).

Description

Title

Method for producing membrane electrode assemblies for an electrochemical cell unit

The present invention relates to a method for producing membrane electrode assemblies with first and second subgaskets and proton exchange membranes for an electrochemical cell unit according to the preamble of claim 1, a method for producing an electrochemical cell unit according to the preamble of claim 14 and an electrochemical cell unit according to the preamble of claim 15.

State of the art

Fuel cell units as galvanic cells convert continuously supplied fuel and oxidizing agents into electrical energy and water using 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 in a stack.

In fuel cell units, a large number of fuel cells are arranged in a fuel cell stack. Within each fuel cell there is a gas space for oxidizing agents, i.e. a flow space for passing oxidizing agents, such as air from the environment with oxygen. The gas space for oxidizing agents is formed by channels on the bipolar plate and by a gas diffusion layer for a cathode. The channels are thus surrounded by a corresponding channel structure of a A bipolar plate is formed and the oxidizing agent, namely oxygen, passes through the gas diffusion layer to the cathodes of the fuel cells. In an analogous manner, a gas space for fuel is available.

Electrolysis cell units made of stacked electrolysis cells, similar to fuel cell units, are used, for example, for the electrolytic production of hydrogen and oxygen from water. Furthermore, fuel cell units are known that can be operated as reversible fuel cell units and thus as electrolysis cell units. Fuel cell units and electrolysis cell units form electrochemical cell units. Fuel cells and electrolysis cells form electrochemical cells. Fuel cells therefore have channels for the process fluids fuel and oxidizing agent. Electrolysis cells have channels for the process fluids electrolytes. The electrochemical cells comprise membrane electrode arrangements.

In the membrane electrode assemblies, proton exchange membranes are mechanically connected to subgaskets using a connecting agent. The membrane electrode assemblies are made up of the anodes, cathodes, subgaskets and proton exchange membranes. The connecting agent is generally adhesive. Before the membrane electrode assemblies are manufactured, the subgaskets are available as a subgasket band that is rolled up on a storage roll. To produce the separate small subgaskets, it is necessary to cut through this subgasket band. It is already known to cut through the subgasket band using a laser beam. However, significant process-related problems arise when cutting through the subgasket band using the laser beam. In particular, the cut edges are not clean and clear after cutting and problems arise with the material of the subgasket that melts away during cutting.

DE 102020 130 578 A1 discloses a method for producing a membrane electrode assembly for a fuel cell, in which a first support film is provided as a web material, in which cutouts are introduced into the first support film in succession and at a distance from one another, in which the first support film provided with cutouts is Processing station is fed, in which a membrane film is fed to the processing station, which comprises a web-shaped electrolyte membrane, on which catalyst layers are applied on both sides in a format, in which the membrane film is cut into membrane film cutouts in the processing station so that a peripheral edge of the electrolyte membrane is formed to the catalyst layers, in which the respective membrane film cutouts with one of the two catalyst layers are aligned to the respective cutout in the first support film and applied to the first support film, in which a second support film is provided as web material, in which cutouts are made in the second support film one after the other and at a distance from one another, in which the second support film is aligned with the respective cutouts to the catalyst layers of the membrane film cutouts opposite the first support film and applied to the first support film, and in which the first and second support films and the membrane film cutouts arranged therebetween are firmly connected to one another to form a film composite. Cutouts are laser-cut into the first and second support films as subgaskets.

US 2022 037690 A1 discloses a method for producing a membrane electrode assembly (MEA) for a fuel cell. Laser cutting is used in the production of the membrane electrode assemblies.

EP 2 097 943 B1 shows a method for producing fuel cell components in a roll-to-roll process. Gaskets are cut off using laser cutting at cutting stations

WO 2008/108898 A2 discloses a method for producing a membrane electrode arrangement. Subgaskets are cut off or openings are machined at a cutting station such as a laser cutter.

Disclosure of the invention

Advantages of the invention

Inventive process for producing

Membrane electrode assemblies with first and second subgaskets and Proton exchange membranes for an electrochemical cell unit for converting electrochemical energy into electrical energy as a fuel cell unit and/or for converting electrical energy into electrochemical energy as an electrolysis cell unit, comprising the steps of: providing one proton exchange membrane each, providing a subgasket, severing the subgasket with a separating device by means of a laser beam so that a first and second subgasket are produced, arranging one proton exchange membrane each between the first and second subgaskets, connecting one proton exchange membrane each to the first and second subgaskets to form the membrane electrode arrangement, wherein the subgasket is severed with the laser beam by directing the laser beam onto a primary side of the subgasket and a focal spot of the laser beam performs a relative movement on the primary side of the subgasket during the severing and simultaneously a secondary side of the subgasket rests on a conveyor device and the secondary side of the subgasket has a surface facing the primary side opposite side of the subgasket. Severing is a cutting operation.

In a further embodiment, during the cutting through of the subgasket with the laser beam, a movement, in particular a translational and/or rotational movement, is carried out from an area of the subgasket on which the focal spot of the laser beam impinges. Preferably, the area of the subgasket is an area of the subgasket with the focal spot and preferably additionally an area with a distance from the focal spot that is smaller than the diameter of the focal spot.

In an additional embodiment, during the cutting of the subgasket with the laser beam, a section of the subgasket rests with the secondary side on a contact surface of the conveyor device and the focal spot of the laser beam is positioned on this section and/or surrounded by this section, in particular in the circumferential direction of a conveyor device as a roller. Preferably, the section of the subgasket which rests with the secondary side on a contact surface of the conveyor device comprises the subgasket on and/or at a recess the conveying device and the subgasket is arranged on and/or at the recess so that the contact surface extends to the recess.

In a supplementary variant, during the cutting of the subgasket with the laser beam, essentially no relative movement is carried out between the secondary side of the subgasket and the contact surface of the conveyor device. Essentially no slippage therefore occurs between the secondary side of the subgasket and the contact surface of the conveyor device. Essentially no relative movement between the secondary side of the subgasket and the contact surface of the conveyor device preferably means that the speed of the relative movement is less than 10%, 5%, 3%, 2% or 1% of the speed, in particular rotation speed or path speed, of the contact surface of the conveyor device.

In an additional embodiment, a movement, in particular a translational and/or rotational movement, is carried out by the contact surface of the conveying device during the cutting of the subgasket with the laser beam.

Preferably, a recess is formed on the contact surface of the conveying device and during the cutting of the subgasket with the laser beam there is no contact locally between the secondary side of the subgasket and the conveying device at the recess.

In a further embodiment, the relative movement on the primary side of the subgasket is carried out by the focal spot of the laser beam during the cutting process and on the secondary side of the subgasket, opposite the focal spot on the primary side, a fictitious secondary focal spot carries out a relative movement on the secondary side of the subgasket. The secondary focal spot preferably has the same size and/or geometry as the focal spot.

In a supplementary variant, the relative movement of the fictitious secondary focal spot during the cutting on the secondary side of the subgasket is carried out, in particular during the entire period of cutting with the laser beam, so that the fictitious Secondary focal spot has no fictitious contact with the conveying device, in particular with the contact surface of the conveying device.

In an additional embodiment, the fictitious secondary focal spot of the laser beam performs a relative movement on the secondary side of the subgasket during the cutting process, so that the fictitious secondary focal spot is arranged at and/or on and/or in the recess of the conveyor device, in particular during the entire period of cutting with the laser beam. The process reliability of the cutting process is thereby significantly increased because, in particular, molten subgasket can accumulate in the recess during the cutting process without thereby impairing the process reliability.

In particular, the conveying device is designed as a rotating roller with a radial outer side of the roller as the contact surface.

In a supplementary variant, the recess is designed as a preferably curved longitudinal slot in the circumferential direction of the radial outside of the roller as the contact surface for severing the subgasket in the direction of movement of the subgasket. The curvature of the longitudinal slot preferably corresponds to the curvature of the radial outside of the roller.

In a further embodiment, the recess is designed as a, preferably straight, transverse slot in the direction of a rotation axis of the roller for severing the subgasket on the contact surface perpendicular to the direction of movement of the subgasket.

In an additional variant, the first and/or second subgasket are produced by removing a strip as a subgasket from a storage device and separating individual first and/or second subgaskets from the strip by means of cutting with the laser beam.

Inventive method for producing an electrochemical cell unit for converting electrochemical energy into electrical energy as a fuel cell unit and/or for converting electrical energy into electrochemical energy as an electrolysis cell unit with stacked electrochemical cells with the steps: providing layered components of the electrochemical cells, namely membrane electrode arrangements each with a proton exchange membrane, a first subgasket, a second subgasket, an anode, a cathode and preferably gas diffusion layers and bipolar plates, stacking the layered components to form electrochemical cells and a stack of the electrochemical cell unit, wherein the membrane electrode arrangements are provided by carrying out a method described in this patent application.

Electrochemical cell unit according to the invention for converting electrochemical energy into electrical energy as a fuel cell unit and/or for converting electrical energy into electrochemical energy as an electrolysis cell unit, comprising stacked electrochemical cells and the electrochemical cells each comprise stacked layered components and the components of the electrochemical cells are membrane electrode arrangements each with a proton exchange membrane, a first subgasket, a second subgasket, an anode, a cathode and preferably gas diffusion layers and bipolar plates, wherein the electrochemical cell unit is produced using a method described in this patent application and/or the cut edges of the first and/or second subgaskets are fused due to thermal severing at the cut edges with a laser beam.

In a supplementary variant, the first and/or second subgasket will be produced by incorporating a recess as an opening in each subgasket by cutting through each subgasket with the laser beam, in particular completely around the recess as an opening, in particular as a perforation and/or as a completely continuous cut.

In a further embodiment, the first and/or second subgasket will be produced by incorporating at least one fluid opening into each subgasket by irradiating each subgasket with the laser beam, in particular completely circumferentially at the at least one fluid opening. severed, in particular as a perforation and/or as a completely continuous cut.

In a further variant, the focal spot and/or the fictitious secondary focal spot is at a distance from the conveyor device, in particular the roller, during the entire period of cutting through the subgasket with the laser beam, in particular continuously; in particular, the distance from the conveyor device is preferably always greater than 0.5 times, 1 time, 2 times, 3 times or 5 times the maximum diameter of the focal spot and/or laser beam. Due to this sufficient distance, the cutting edge on the subgasket can be formed precisely and straight.

In a supplementary embodiment, the connection of each proton exchange membrane with the first and second subgasket to form the membrane electrode arrangement is carried out in a material-locking and/or form-locking manner, in particular by means of an adhesive.

In an additional embodiment, the conveyor is designed with a straight contact surface and the conveyor is moved such that it only alternately has contact with the secondary side of the subgasket during severing and the severing is only carried out during this temporary contact.

In an additional embodiment, the position of the subgasket and/or the subgasket belt and/or the conveyor device relative to the laser system is recorded by means of a camera and an image capture system and/or by means of the data on the movement, in particular rotational movement, of the conveyor device and/or the subgasket. The data on the movement, in particular rotational movement, also include data on the position, in particular rotational position, of the conveyor device and/or the subgasket. The data on the movement, in particular rotational movement, also include data on the speed.

In a further embodiment, the position of the focal spot of the laser beam on the primary side of the subgasket is controlled and/or regulated by means of the optical system of the laser system. The laser beam and so that the focal spot is preferably controlled and/or regulated taking into account the movement of the subgasket and/or the conveying device and/or the position of the subgasket and/or the position of the at least one recess of the conveying device, so that the severing is carried out at the intended position of the subgasket and preferably the fictitious secondary focal spot is arranged on and/or on and/or in the recess of the conveying device, in particular during the entire duration of the severing with the laser beam.

In a further variant, the subgasket is provided as a band-shaped subgasket and/or as a subgasket band.

In a supplementary variant, the band-shaped subgasket and/or the subgasket as a band is severed by means of the laser beam so that the first and second subgasket are produced.

In a further variant, one proton exchange membrane is provided in each case, so that the proton exchange membrane, in addition to the actual proton exchange membrane, has the anode, the cathode and preferably the catalyst layer on and/or in the anode and on and/or in the cathode as further layers.

In a supplementary embodiment, the

Proton exchange membrane as a band and/or the band-shaped proton exchange membrane in addition to the actual proton exchange membrane as further layers the anode, the cathode and preferably on the and/or in the anode and on the and/or in the cathode the catalyst layer is arranged and/or preferably the catalyst layer is integrated into the cathode and anode.

In a further embodiment, the contact plates are monopolar plates and/or bipolar plates and/or end plates.

In a further embodiment, at least 90% of the electrochemical cells, in particular all electrochemical cells, of the electrochemical cell unit are designed as described in this patent application. In an additional variant, the electrolysis cell unit is additionally designed as a fuel cell unit, in particular a fuel cell unit described in this patent application, so that the electrolysis cell unit forms a reversible fuel cell unit.

In a further variant, the electrochemical cell unit comprises a housing and/or a connection plate. The stack is enclosed by the housing and/or the connection plate.

In a further embodiment, the fuel cell unit described in this patent application additionally forms an electrolysis cell unit and preferably vice versa.

Preferably the fuel is hydrogen, hydrogen-rich gas, reformate gas or natural gas.

Advantageously, the fuel cells and/or electrolysis cells are essentially flat and/or disc-shaped.

In a complementary variant, the oxidizing agent is air with oxygen or pure oxygen.

Preferably, the fuel cell unit is a PEM fuel cell unit with PEM fuel cells or an SOFC fuel cell unit with SOFC fuel cells or an alkaline fuel cell (AFC).

Computer-implemented method according to the invention comprising steps of the method described in this patent application.

The invention further comprises a computer program with program code means stored on a computer-readable data carrier in order to carry out a method described in this patent application when the computer program is executed on a computer, in particular a control and/or regulating unit, or a corresponding computing unit. The invention also includes a computer program product with program code means stored on a computer-readable data carrier in order to carry out a method described in this patent application when the computer program is executed on a computer, in particular a control and/or regulating unit, or a corresponding computing unit. The computer program product is a memory for storing the computer program, for example a CD, a hard disk and/or a USB stick.

Short description of the drawings

In the following, embodiments of the invention are described in more detail with reference to the accompanying drawings.

Fig. 1 is a highly simplified exploded view of an electrochemical cell system as a fuel cell system and electrolysis cell system with components of an electrochemical cell as a fuel cell and electrolysis cell,

Fig. 2 is a perspective view of part of a fuel cell and electrolysis cell,

Fig. 3 a longitudinal section through electrochemical cells as fuel cell and electrolysis cell,

Fig. 4 is a perspective view of an electrochemical cell unit as a fuel cell unit and an electrolysis cell unit as a fuel cell stack and an electrolysis cell stack,

Fig. 5 is a side view of the electrochemical cell unit as a fuel cell unit and electrolysis cell unit as a fuel cell stack and electrolysis cell stack,

Fig. 6 is a perspective view of a bipolar plate, Fig. 7 is a perspective view of a membrane electrode assembly,

Fig. 8 shows a partial section through a membrane electrode arrangement and two gas diffusion layers of an electrochemical cell,

Fig. 9 shows a highly simplified longitudinal section through a machine system for producing the membrane electrode assembly,

Fig. 10 a section through a laser system with a laser and an optical system as well as a conveyor device as a roller and the subgasket which rests on the roller,

Fig. 11 is a plan view of the conveyor device as a roller in a first embodiment according to Fig. 10 and

Fig. 12 is a plan view of the conveyor device as a roller in a second embodiment.

The basic structure of a fuel cell 2 as a PEM fuel cell 3 (polymer electrolyte fuel cell 3) is shown in Figs. 1 to 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 fed to an anode 7 as a gaseous fuel and the anode 7 forms the negative pole. A gaseous oxidizing agent, namely air with oxygen, is fed to a cathode 8, i.e. the oxygen in the air provides the necessary gaseous oxidizing agent. Reduction (electron absorption) takes place at the cathode 8. Oxidation as electron release is carried out at the anode 7.

The redox equations of the electrochemical processes are:

Cathode:

O ₂ + 4 H ⁺ + 4 e- -» 2 H ₂ O

Anode: 2 H ₂ -» 4 H ⁺ + 4 e-

Total reaction equation of cathode and anode: 2 H ₂ + O ₂ -» 2 H ₂ O

The difference between the normal potentials of the electrode pairs under standard conditions as a reversible fuel cell voltage or open circuit voltage of the unloaded fuel cell 2 is 1.23 V. This theoretical voltage of 1.23 V is not achieved in practice. In the idle state and with small currents, voltages of over 1.0 V can be achieved, and when operating with larger currents, voltages between 0.5 V and 1.0 V are achieved. The series connection of several fuel cells 2, in particular a fuel cell unit 1 as a fuel cell stack 1 of several stacked fuel cells 2, 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 comprises a proton exchange membrane 5 (Proton Exchange Membrane, PEM), which is arranged between the anode 7 and the cathode 8. The anode 7 and cathode 8 are layered or disc-shaped. The PEM 5 functions as an electrolyte, catalyst carrier and separator for the reaction gases. The PEM 5 also functions as an electrical insulator and prevents an electrical short circuit between the anode 7 and cathode 8. In general, for 5 pm to 150 pm thick layers with expanded films with openings as a carrier layer and proton-conducting membrane materials with membrane effect attached to them are used as perfluorinated and/or sulfonated compounds for the PEM 5. The PEM 5 conducts the protons H ⁺ and essentially blocks ions other than protons H ⁺ , so that charge transport can take place due to the permeability of the PEM 5 for the protons H ⁺ . The PEM 5 is essentially impermeable to the reaction gases oxygen O ₂ and hydrogen H ₂ , ie it blocks the flow of oxygen O ₂ and hydrogen H ₂ between a gas space 31 at the anode 7 with fuel hydrogen H ₂ and the gas space 32 at the cathode 8 with air or oxygen O ₂ as oxidizing agent. The proton conductivity of the PEM 5 increases with increasing temperature and increasing water content. On the two sides of the PEM 5, each facing the gas spaces 31, 32, the electrodes 7, 8 are located as the anode 7 and cathode 8. A unit made up of the PEM 5 and the electrodes 7, 8 is referred to as a membrane electrode assembly 6 (MEA). The electrodes 7, 8 are pressed with the PEM 5. The electrodes 7, 8 are platinum-containing carbon particles that are bound to PTFE (polytetrafluoroethylene), FEP (fluorinated ethylene-propylene copolymer), PFA (perfluoroalkoxy), PVDF (polyvinylidene fluoride) and/or PVA (polyvinyl alcohol) and are hot-pressed into microporous carbon fiber, glass fiber or plastic mats. A catalyst layer 30 is normally applied to the electrodes 7, 8 on the side facing the gas spaces 31, 32 (not shown). The catalyst layer 30 on the gas space 31 with fuel at the anode 7 comprises nanodisperse platinum-ruthenium on graphitized soot particles that are bound to a binding agent. The catalyst layer 30 on the gas space 32 with oxidizing agent at the cathode 8 similarly comprises nanodisperse platinum. For example, Nation®, a PTFE emulsion or polyvinyl alcohol are used as binding agents.

Deviating from this, the electrodes 7, 8 are made of an ionomer, for example Nation®, platinum-containing carbon particles and additives. These electrodes 7, 8 with the ionomer are electrically conductive due to the carbon particles and also conduct the protons H ⁺ and additionally function as a catalyst layer 30 due to the platinum-containing carbon particles. Membrane electrode arrangements 6 with these electrodes 7, 8 comprising the ionomer form membrane electrode arrangements 6 as CCM (catalyst coated membrane).

A gas diffusion layer 9 (GDL) is placed on the anode 7 and the cathode 8. The gas diffusion layer 9 on the anode 7 distributes the fuel from channels 12 for fuel evenly to the catalyst layer 30 on the anode 7. The gas diffusion layer 9 on the cathode 8 distributes the oxidant from channels 13 for oxidant evenly to the catalyst layer 30 on the cathode 8. The GDL 9 also draws off reaction water in the opposite direction to the flow direction of the reaction gases, ie in one direction from the catalyst layer 30 to the Channels 12, 13. Furthermore, the GDL 9 keeps the PEM 5 moist and conducts the current. The GDL 9 is constructed, for example, from a hydrophobic carbon paper as a carrier and substrate layer and a bonded carbon powder layer as a microporous layer.

A bipolar plate 10 rests on the GDL 9. The electrically conductive bipolar plate 10 serves as a current collector, for draining water and for conducting the reaction gases as process fluids through the channel structures 29 and/or flow fields 29 and for dissipating the waste heat, which occurs in particular during the exothermic electrochemical reaction at the cathode 8. To dissipate the waste heat, channels 14 are incorporated into the bipolar plate 10 as a channel structure 29 for conducting a liquid or gaseous coolant as a process fluid. 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 oxidizing agents is formed by channels 13. The material used for the bipolar plates 10 is, for example, metal, conductive plastics and composite materials and/or graphite.

In a fuel cell unit 1, several fuel cells 2 are arranged in a flush stack (Fig. 4 and 5). Fig. 1 shows an exploded view of two fuel cells 2 arranged in a flush stack.

Seals 11 seal the gas spaces 31, 32 or channels 12, 13 in a fluid-tight manner. Hydrogen H2 is stored as fuel in a compressed gas reservoir 21 (Fig. 1) at a pressure of, for example, 350 bar to 700 bar. From the compressed gas reservoir 21, the fuel is led 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. From the medium-pressure line 17, the fuel is led to an injector 19. At the injector 19, the pressure of the fuel is reduced to an injection pressure of between 1 bar and 3 bar. From the injector 19, the fuel is fed to a fuel supply line 16 (Fig. 1) and from the supply line 16 to the fuel channels 12, which form the fuel channel structure 29. The fuel thereby 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 at the anode 7. After flowing through the channels 12, the fuel not consumed in the redox reaction at the anode 7 and, if applicable, Water from a controlled humidification of the anode 7 is drained from the fuel cells 2 through a discharge line 15.

A gas conveying device 22, for example designed as a blower 23 or a compressor 24, conveys air from the environment as an oxidizing agent into a supply line 25 for oxidizing agents. The air is fed from the supply line 25 to the channels 13 for oxidizing agents, which form a channel structure 29 on the bipolar plates 10 for oxidizing agents, 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. After flowing through the channels 13 or the gas space 32 for the oxidizing agent 32, the oxidizing agent not used at the cathode 8 and the reaction water formed at the cathode 8 due to the electrochemical redox reaction are discharged from the fuel cells 2 through a discharge line 26. 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. The supply and discharge lines 15, 16, 25, 26, 27, 28 are shown as separate lines in Fig. 1 for the sake of simplicity. At the end region near the channels 12, 13, 14 in the cell stack 65 of the fuel cell unit 1, aligned fluid openings 41 are formed on sealing plates 39 as an extension at the end region 40 of the superimposed bipolar plates 10 (Fig. 6) and on the subgaskets 62 of the membrane electrode arrangements 6 (Fig. 7). The fuel cells 2 and the components of the fuel cells 2 are disk-shaped and span fictitious planes 59 that are essentially parallel to one another. The aligned fluid openings 41 and seals (not shown) in a direction perpendicular to the fictitious planes 59 between the fluid openings 41 thus form a supply channel 42 for oxidizing agent, a discharge channel 43 for oxidizing agent, a supply channel 44 for fuel, a discharge channel 45 for fuel, a supply channel 46 for coolant and a discharge channel 47 for coolant. The supply and discharge lines 15, 16, 25, 26, 27, 28 outside the cell stack 65 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 cell stack 65 of the fuel cell unit 1 open into the supply and discharge channels 42, 43, 44, 45, 46, 47 inside the cell stack 65 of the fuel cell unit 1. The Fuel cell unit 1 together with the compressed gas storage 21 and the gas conveying device 22 forms a fuel cell system 4.

In the fuel cell unit 1, the fuel cells 2 are arranged between two clamping elements 33 as clamping plates 34. A first clamping plate 35 rests on the first fuel cell 2 and a second clamping plate 36 rests on the last fuel cell 2. The fuel cell unit 1 comprises approximately 200 to 400 fuel cells 2, which are not all shown in Fig. 4 and 5 for reasons of clarity. The clamping elements 33 apply a compressive force to the fuel cells 2, i.e. the first clamping plate 35 rests with a compressive force on the first fuel cell 2 and the second clamping plate 36 rests with a compressive force on the last fuel cell 2. The fuel cell stack 2 is thus clamped in order to ensure the tightness for the fuel, the oxidizing agent and the coolant, in particular due to the elastic seals 11, and also to keep the electrical contact resistance within the fuel cell stack 1 as low as possible. In order to clamp the fuel cells 2 with the clamping elements 33, four connecting devices 37 are designed as bolts 38 on the fuel cell unit 1, which are subjected to tensile stress. The four bolts 38 are connected to the chipboards 34.

Fig. 6 shows the bipolar plate 10 of the fuel cell 2. The bipolar plate 10 comprises 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 rather simply as a layer of a channel structure 29. The fluid openings 41 on the sealing plates 39 of the bipolar plates 10 (Fig. 6) and on the subgaskets 62 of the membrane electrode assemblies 6 (Fig. 7) are arranged in an aligned stack within the fuel cell unit 1, so that supply and discharge channels 42, 43, 44, 45, 46, 47 are formed. Seals (not shown) are arranged between the sealing plates 39 for fluid-tight sealing of the supply and discharge channels 42, 43, 44, 45, 46, 47 formed by the fluid openings 41.

Since the bipolar plate 10 also separates the gas space 31 for fuel from the gas space 32 for oxidizing agent in a fluid-tight manner and also seals the channel 14 for coolant in a fluid-tight manner, the bipolar plate 10 can also be used the term separator plate for fluid-tight separation of process fluids can be chosen. The term separator plate is therefore also subsumed under the term bipolar plate 10 and vice versa. The channels 12 for fuel, the channels 13 for oxidizing agents and the channels 14 for coolant of the fuel cell 2 are also formed on the electrochemical cell 52, but with a different function.

The fuel cell unit 1 can also be used and operated as an electrolysis cell unit 49, ie forms a reversible fuel cell unit 1. Some features are described below which enable the operation of the fuel cell unit 1 as an electrolysis cell unit 49. A liquid electrolyte, namely highly diluted sulfuric acid with a concentration of approximately c (H2SO4) = 1 mol/l, is used for the electrolysis. A sufficient concentration of oxonium ions H ₃ 0 ⁺ in the liquid electrolyte is necessary for the electrolysis.

During electrolysis, the following redox reactions occur:

Cathode:

4 H ₃ O ⁺ + 4 e- -» 2 H ₂ + 4 H ₂ O

Anode:

6 H ₂ O — » O ₂ + 4 H ₃ O ⁺ + 4 e'

Total reaction equation of cathode and anode:

2 H ₂ O -» 2 H ₂ + O ₂

The polarity of the electrodes 7, 8 is reversed (not shown) with electrolysis when operating as an electrolysis cell unit 49 as when operating as a fuel cell unit 1, so that hydrogen H ₂ is formed as a second substance at the cathodes in the channels 12 for fuel, through which the liquid electrolyte is passed, and the hydrogen H ₂ is absorbed by the liquid electrolyte and transported along in dissolved form. The liquid electrolyte is passed through the channels 13 for oxidizing agents in the same way and oxygen O ₂ is formed as the first substance at the anodes in or on the channels 13 for oxidizing agents. Fuel cells 2 of the fuel cell unit 1 function as electrolysis cells 50 when operating as an electrolysis cell unit 49. The fuel cells 2 and electrolysis cells 50 thus form electrochemical cells 52. The oxygen O2 formed is absorbed by the liquid electrolyte and transported along in dissolved form. The liquid electrolyte is stored in a storage container 54. For reasons of simplifying the drawing, Fig. 1 shows two storage containers 54 of the fuel cell system 4, which also functions as an electrolysis cell system 48. The 3-way valve 55 on the feed line 16 for fuel is switched over when operating as an electrolysis cell unit 49, so that not fuel from the compressed gas storage 21, but the liquid electrolyte is fed from the storage container 54 into the feed line 16 for fuel using a pump 56. A 3-way valve 55 on the oxidizing agent supply line 25 is switched over during operation as an electrolysis cell unit 49, so that not oxidizing agent as air from the gas conveyor 22, but the liquid electrolyte with the pump 56 from the storage tank 54 is introduced into the oxidizing agent supply line 25. The fuel cell unit 1, which also functions as an electrolysis cell unit 49, has optional modifications to the electrodes 7, 8 and the gas diffusion layer 9 compared to a fuel cell unit 1 that can only be operated as a fuel cell unit 1: for example, the gas diffusion layer 9 is not absorbent, so that the liquid electrolyte easily drains off completely, or the gas diffusion layer 9 is not formed, or the gas diffusion layer 9 is a structure on the bipolar plate 10. The electrolysis cell unit 49 with the storage container 54, the pump 56 and the separators 57, 58 and preferably the 3-way valve 55 forms an electrochemical cell system 60.

A separator 57 for hydrogen is arranged on the discharge line 15 for fuel. The separator 57 separates the hydrogen from the electrolyte with hydrogen and the separated hydrogen is introduced into the pressure gas storage 21 by a compressor (not shown). The electrolyte discharged from the separator 57 for hydrogen is then fed back to the storage container 54 for the electrolyte by a line. A separator 58 for oxygen is arranged on the discharge line 26 for fuel. The separator 58 separates the oxygen from the electrolyte with oxygen and the separated oxygen is fed into the pressure gas storage 21 by a compressor (not shown). Compressor in a compressed gas storage tank for oxygen (not shown). The oxygen in the compressed gas storage tank for oxygen (not shown) can optionally be used for operating the fuel cell unit 1 by sliding the oxygen into the feed line 25 for oxidizing agent via a line (not shown) when operating as a fuel cell unit 1. The electrolyte derived from the oxygen separator 58 is then fed back to the storage container 54 for the electrolyte via a line. The channels 12, 13 and the discharge and feed lines 15, 16, 25, 26 are designed such that after use as an electrolysis cell unit 49 and the pump 56 is switched off, the liquid electrolyte flows completely back into the storage container 54 due to gravity. Optionally, after use as an electrolysis cell unit 49 and before use as a fuel cell unit 1, an inert gas is passed through the channels 12, 13 and the discharge and supply lines 15, 16, 25, 26 to completely remove the liquid electrolyte before gaseous fuel and oxidizing agent are passed through. The fuel cells 2 and the electrolysis cells 2 thus form electrochemical cells 52. The fuel cell unit 1 and the electrolysis cell unit 49 thus form an electrochemical cell unit 53. The channels 12 for fuel and the channels for oxidizing agent thus form channels 12, 13 for passing the liquid electrolyte through when operating as an electrolysis cell unit 49 and this applies analogously to the supply and discharge lines 15, 16, 25, 26. For process-related reasons, an electrolysis cell unit 49 normally does not require channels 14 for passing coolant through. In an electrochemical cell unit 49, the channels 12 for fuel also form channels 12 for passing fuel and/or electrolytes and the channels 13 for oxidizer also form channels 13 for passing fuel and/or electrolytes.

In a further embodiment, not shown, the fuel cell unit 1 is designed as an alkaline fuel cell unit 1. Potassium hydroxide solution is used as the mobile electrolyte. The fuel cells 2 are arranged in a stack. A monopolar cell structure or a bipolar cell structure can be formed. The potassium hydroxide solution circulates between an anode and cathode and transports reaction water, heat and impurities (carbonates, dissolved gases). The fuel cell unit 1 can also be operated as a reversible fuel cell unit 1, ie as an electrolysis cell unit 49.

Contact plates 51 can be designed as monopolar plates, bipolar plates 10 or end plates. Monopolar plates have only one uniform pole on both sides, so that in a fuel cell unit 1 with monopolar plates, the monopolar plates are to be connected to other monopolar plates with an electrical power line. End plates are arranged at one end of the cell stack.

To produce an electrochemical cell unit 53, the layered components 5, 6, 7, 8, 9, 10, 51, 62, 63, 64, 76, 77 of electrochemical cells 52 are first provided. The layered components 5, 6, 7, 8, 9, 10, 51, 62, 63, 64, 76, 77 are, for example, in a fuel cell unit 1, a proton exchange membrane 5, an anode 7, a cathode 8, a gas diffusion layer 9 and a bipolar plate 10. The anode 7, the cathode 8 and the proton exchange membrane 5 together with first and second subgaskets

63, 64 a membrane electrode arrangement 6 (Fig. 8) in which the anode 7 and the cathode 8 are additionally provided with a catalyst substance as a CCM (catalyst coated membrane), so that the anode 7 and the cathode 8 additionally form a catalyst layer 30. The subgaskets 62 are films which separate the fuel in the gas space 31 for fuel from the oxidant in the gas space 32 for oxidant and support and tension the membrane electrode arrangement 6 without subgaskets 62, 63, 64, i.e. essentially the proton exchange membrane 5. The subgaskets 62 are made, for example, from PEEK (polyetheretherketone) or PPS (polyphenylene sulfide). The layered components 5, 6, 7, 8, 9, 10, 51, 62, 63, 64, 76, 77 of the fuel cells 2 are stacked to form a cell stack 65, for example shown in Fig. 3 and 4. After the layered components 5, 6, 7, 8, 9, 10, 51, 62, 63, 64, 76, 77 have been provided, the layered components 5, 6, 7, 8, 9, 10, 51, 62, 63,

64, 76, 77 executed.

In Fig. 8 a partial section through the membrane electrode arrangement 5 and two gas diffusion layers 9 of the electrochemical cells 52 is shown. In the electrochemical cell 52 has a total of 2 subgaskets 62, ie a first subgasket 63 and a second subgasket 64. In addition, there are 2 gas diffusion layers 9, namely a first gas diffusion layer 76 and a second gas diffusion layer 77. The first subgasket 63 and the second subgasket 64 are firmly bonded to one another using an adhesive 78. The anode 7 has an outer side 79 which is substantially parallel to the fictitious plane 59. The cathode 8 has an outer side 80 which is oriented substantially parallel to the fictitious plane 59. At an edge or end region of the outer side 79, the first subgasket 63 is connected to this edge region of the outer side 79 with the adhesive 78, so that this adhesive 78 on the outer side 79 also forms a connecting means 71 for mechanically connecting the first subgasket 63 to the anode 7. In an analogous manner, the outer side 80 of the cathode 8 is materially connected to the second subgasket 64 with the adhesive 78, so that the adhesive 78 on the outer side 80 of the cathode 8 also forms the connecting means 71. The first and second subgaskets 63, 64 have a substantially rectangular recess 75 (Fig. 7) at which the anode 7 and cathode 8 each protrude into the gas space 31, 32 for the electrochemical reaction. This rectangular recess 75 as opening 75 is delimited by ends 66 of the first subgasket 63 and the second subgasket 64 and these ends 66 of the first and second subgaskets 63, 64 rest on the anode 7 and the cathode 8.

Fig. 9 shows a machine system for carrying out a method for producing the membrane electrode assembly 6. The machine system comprises two bearing devices 94 as bearing rollers 95 for the subgasket 62 as a band 93. The band-shaped subgasket 62, 93 is unrolled from the bearing rollers 95 with a device not shown to the band 93 of the subgasket 62 as a subgasket band 93 and on the bearing roller 95 more than 50, 100 or 300 first and second substantially rectangular subgaskets 62 are connected to one another. In addition, the proton exchange membrane 5 is rolled up as a band 98 on a bearing device 96 as a bearing roller 97, so that a large number, for example more than 50, 100 or 300, essentially rectangular proton exchange membranes 5 are arranged on the proton exchange membrane band 98, connected to one another as a proton exchange membrane band 98. The In addition to the actual proton exchange membrane 5, the proton exchange membrane band 98 comprises the anodes 7, the cathodes 8 and the catalyst layer 30 on and/or integrated into the anode 7 and cathode 8 as additional layers. The first and second subgasket bands 93 and the proton exchange membrane band 98 are simultaneously unrolled from the bearing rollers 95, 97. The first subgasket band 93 is unrolled from a first bearing device 94 for the first subgasket band 93 and the second subgasket band 93 is unrolled from the second bearing device 94.

In order to provide the first subgasket 63 and the second subgasket 64, it is necessary to cut through the first and second subgasket bands 93 using a cutting device in the form of a laser system 74 and a conveyor device 86 in the form of a roller 87. The term subgasket 62 also includes the subgasket band 93. The laser system 74 includes a laser 72 and an optical system 73 (Fig. 10). The optical system 73 includes at least one mirror and/or at least one lens (not shown). The laser 72 emits a laser beam 81, which is deflected by the optical system 73. The subgasket band 93 and also the first and second subgaskets 63, 64 have a primary side 84 and a secondary side 85 (Figs. 9 and 10). The primary side 84 is formed opposite the secondary side 85. The primary side 84 faces the laser beam 81, so that the laser beam 81 striking the primary side 84 forms a focal spot 82. Fictitiously opposite the focal spot 82 is a fictitious secondary focal spot 83 on the secondary side 85 of the subgasket 62 and the subgasket band 93. The energy of the electromagnetic radiation of the laser beam 81 heats the subgasket 62 locally at the focal spot 82, so that due to the high temperature of the subgasket 62 and the subgasket band 93 at the focal spot 82, the latter is severed, i.e. cut off. The focal spot 82 of the laser beam 81 performs a relative movement on the primary side 84 of the subgasket 62 while the subgasket 62 and/or the subgasket band 93 is being severed.

During this cutting, the secondary side 85 of the subgasket 62 and/or the subgasket band 93 rests on a contact surface 89 of the conveyor device 86 as the roller 87. The contact surface 89 is a partial surface a radial outer side 100 of the roller 87. The roller 87 executes a rotational movement about the rotation axis 99 during the cutting, so that the radial outer side 100 and thus also the contact surface 89 execute a rotational movement. Due to the resting of the secondary side 85 of the subgasket 62 and/or the subgasket band 93, i.e. a section 61 of the subgasket 62 and/or the subgasket band 93 on the contact surface 89 of the roller 87, the subgasket 62 and/or the subgasket band 93 also locally executes this rotational movement about the rotation axis 99 simultaneously and essentially identically, so that essentially no relative movement occurs between the secondary side 85 of the subgasket 62 and/or the subgasket band 93 and the contact surface 89 of the roller 87.

As a result, an area 88 of the subgasket 62 in the vicinity of the focal spot 82 also carries out this movement as a rotational movement. Recesses 90 are machined into the radial outer side 100 of the roller 87 as straight or curved slots. The recesses 90 are designed as recesses 91 in the circumferential direction of the radial outer side 100 of the roller 87 (Fig. 12) and/or as recesses 92 in the direction of the rotation axis 99 of the roller 87 (Figs. 11 and 12). During the movement as a rotational movement of the subgasket 62 and/or the subgasket band 93 on the roller 87, the focal spot 82 simultaneously carries out the relative movement on the primary side 84 in such a way that the fictitious secondary focal spot 83 is constantly arranged and positioned at and/or on and/or in a recess 90 during the cutting process. The fictitious secondary focal spot 83 thus has no fictitious contact with the radial outer side 100 and thus with the contact surface 89 of the roller 87 during the cutting. This lack of contact of the fictitious secondary focal spot 83 with the conveyor device 86 as the roller 87 is necessary so that a

Cutting edge 67 is cleanly formed without defects after severing and molten material of the subgasket 62 can collect in the recess 90 for good process safety and process reliability. The severing takes place on a straight cutting edge 67 with a straight recess 90, without taking into account the curvature of the radial outer side 100 of the roller 87, so that the recess 91 is considered to be straight in the circumferential direction in this respect. For the formation of

Cutting edges 67 with a curvature, it is necessary that the Recesses 90 are curved (not shown) without taking into account the curvature of the radial outer side 100 of the roller 87. Preferably, the melted material is removed from the at least one recess 90 simultaneously during the cutting, for example by means of compressed air and/or a mechanical cleaning device, in particular a rotating mechanical cleaning device.

After the 2 subgasket bands 93 have been unrolled or unwound from the 2 storage devices 94, they are each completely severed with the laser beam 81 in the transverse direction, i.e. in the direction of the rotation axis 99 of the roll 87, as described above, so that the separate first and second subgaskets 63, 64 are formed. The laser system 74 also cuts six fluid openings 41 into each first subgasket 62, 63 with the laser beam 81 and also a perforation for the large opening 75 as the recess 75 for the proton exchange membrane 5, so that the proton exchange membrane 5 is accessible through the opening 75 for the process fluids for the electrochemical reaction after the later complete severing of the perforation. This severing is carried out for one subgasket 63, 64 each with 2 laser systems 74 and 2 conveyor devices 86. The two laser systems 74 and the conveyor device 86 are arranged one after the other in the direction of movement of the subgaskets 63, 64 (Fig. 9).

The proton exchange membrane band 98 is cut off by a separating device 101 as a cutting roller 102 and a further driven roller is arranged under the cutting roller 102 so that the proton exchange membrane band 98 is guided between the cutting roller 102 and the further roller so that these also function as a conveyor device for unwinding the proton exchange membrane band 98 from the bearing roller 97. The cutting roller 102 cuts off individual, essentially rectangular sections from the proton exchange membrane band 99 and these cut sections form the individual proton exchange membranes 5.

Subsequently, in the device 103, for example a laminating roller 103, for connecting the cut Proton exchange membranes 5 are connected to the first subgasket 63 cut off by means of the laser beam 81, the proton exchange membranes 5 are connected to the first subgasket 63. The connection is carried out in a material-locking and/or form-locking manner, for example by gluing, embossing and/or hot lamination. The second subgasket 64 is then placed on the first subgasket 63 and the individual proton exchange membranes 5 that have already been cut off, so that the fluid openings 41 and the

Recesses 75 as openings 75 in the first and second subgaskets 62, 63, 64 are aligned and thus the proton exchange membranes 5 are arranged between the first and second subgaskets 62, 63, 64. In the device 104 as two laminating rollers 104 for connecting the first and second subgaskets 62, 63, 64 to one another and to the proton exchange membranes 5, the first and second subgaskets 63, 64 and the proton exchange membranes 5 are connected to one another by laminating and/or embossing, i.e. in a material-locking and/or form-locking manner. In the device 69 for removing and/or lifting, the areas of the first and second subgaskets 63, 64 enclosed by the perforation are removed from the first and second subgaskets 63, 64, i.e. the perforations made with the laser system 74 are completely severed, in particular torn through during removal, so that the proton exchange membranes 5 are accessible at the recesses 75 as openings 55. The device 69 is designed, for example, as a tear-off roller 70 or a vacuum suction device or a vacuum roller.

The membrane electrode arrangements 6 are then transported away by a conveyor belt 68, each with a first subgasket 63, a second subgasket 64, a proton exchange membrane 5, an anode 7 and a cathode 8. The above processes are carried out continuously and simultaneously and are preferably monitored, controlled and/or regulated with cameras and image processing software in a control and/or regulating unit (not shown), in particular with regard to the positions of the proton exchange membranes 5 and the first and second subgaskets 63, 64 as the first and second subgaskets 63, 64 to one another and the relative position of the focal spot 82 on the primary side 84 of the subgasket 62, 63, 64. Deviating from the above description, the first and second subgaskets 63, 64 are provided as a subgasket belt 93 with the separate Proton exchange membranes 5 are materially connected and only after passing through the device 69 for removal and/or lifting does the complete severing in the transverse direction of the first and second subgasket bands 93 take place, so that after the device 69 a further laser system 74 and the conveying device 86 are arranged as the separating device (not shown).

Overall, there are significant advantages associated with the method according to the invention for producing the membrane electrode arrangement 6, the method according to the invention for producing the electrochemical cell unit 53 and the electrochemical cell unit 53 according to the invention. The subgasket 62 is cut through to produce the membrane electrode arrangement 6 exclusively using the laser beam 81 from the laser system 74. Mechanical cutting tools are therefore advantageously not necessary, so that no wear can occur on the non-existent mechanical cutting tool. Different geometries on subgaskets 62, 63, 64 can be made without complex changes to mechanical tools, for example by simply making an adjustment in the software for controlling the relative movement of the focal spot 81 on the primary side 84 of the subgasket 62. The subgasket 62 and/or the subgasket band 93 can be cut through precisely with a clear and straight cutting edge 67 with a high level of process reliability.

Claims

Expectations

1. A method for producing membrane electrode assemblies (6) with first and second subgaskets (62, 63, 64) and proton exchange membranes (5) for an electrochemical cell unit (53) for converting electrochemical energy into electrical energy as a fuel cell unit (1) and/or for converting electrical energy into electrochemical energy as an electrolysis cell unit (49), comprising the steps:

- providing one proton exchange membrane each (5),

- providing a subgasket (62, 93),

- cutting the subgasket (62, 93) with a cutting device by means of a laser beam (81) so that a first and second subgasket (62, 63, 64) are produced,

- arranging one proton exchange membrane (5) between the first and second subgaskets (62, 63, 64),

- Connecting each proton exchange membrane (5) to the first and second subgasket (62, 63, 64) to form the membrane electrode arrangement (6), characterized in that the subgasket (62, 93) is severed with the laser beam (81) by directing the laser beam (81) onto a primary side (84) of the subgasket (62, 93) and a focal spot (82) of the laser beam (81) executes a relative movement on the primary side (84) of the subgasket (62, 93) during the severing and simultaneously a secondary side (85) of the subgasket (62, 93) rests on a conveyor device (86) and the secondary side (85) of the subgasket (62, 93) is a side of the subgasket (62, 93) opposite the primary side (84).

2. Method according to claim 1, characterized in that during the severing of the subgasket (62, 93) with the laser beam (81), a movement, in particular a translational and/or rotational movement, is carried out from a region (88) of the subgasket (62, 93) at which the focal spot (82) of the laser beam (81) impinges.

3. Method according to claim 1 or 2, characterized in that during the severing of the subgasket (62, 93) with the laser beam (81), a section (61) of the subgasket (62, 93) rests with the secondary side (85) on a contact surface (89) of the conveyor device (86) and the focal spot (82) of the laser beam (81) is positioned on this section (61) and/or surrounded by this section (61), in particular in the circumferential direction of a conveyor device (86) as a roller (87).

4. Method according to one or more of the preceding claims, characterized in that during the severing of the subgasket (62, 93) with the laser beam (81) substantially no relative movement is carried out between the secondary side (85) of the subgasket (62, 93) and the contact surface (89) of the conveying device (86).

5. Method according to one or more of the preceding claims, characterized in that during the cutting of the subgasket (62, 93) with the laser beam (81) a movement, in particular a translational and/or rotational movement, is carried out by the contact surface (89) of the conveying device (86).

6. Method according to one or more of the preceding claims, characterized in that a recess (90, 91, 92) is formed on the contact surface (89) of the conveying device (86) and during the severing of the subgasket (62, 93) with the laser beam (81) there is no contact locally between the secondary side (85) of the subgasket (62, 93) and the conveying device (86) at the recess (90, 91, 92).

7. Method according to one or more of the preceding claims, characterized in that the relative movement on the primary side (84) of the subgasket (62, 93) is carried out by the focal spot (82) of the laser beam (81) during the cutting and on the secondary side (85) of the subgasket (62, 93), opposite to the focal spot (84) on the primary side (84), a fictitious secondary focal spot (83) carries out a relative movement on the secondary side (85) of the subgasket (62, 93).

8. Method according to claim 7, characterized in that the relative movement of the fictitious secondary focal spot (83) during the cutting on the secondary side (85) of the subgasket (62, 93) is carried out, in particular during the entire period of cutting with the laser beam (81), so that the fictitious secondary focal spot (83) has no fictitious contact with the conveying device (86), in particular to the contact surface (89) of the conveying device (86).

9. Method according to claim 7 or 8, characterized in that the fictitious secondary focal spot (83) of the laser beam (81) performs a relative movement on the secondary side (85) of the subgasket (62, 93) during the severing process, so that the fictitious secondary focal spot (83), in particular during the entire period of severing with the laser beam (81), is arranged at and/or on and/or in the recess (90, 91, 92) of the conveying device.

10. Method according to one or more of the preceding claims, characterized in that the conveying device (86) is designed as a rotating roller (87) with a radial outer side (100) of the roller (87) as the contact surface (89)

11. Method according to claim 10, characterized in that the recess (90, 91) is designed as a, preferably curved, longitudinal slot (91) in the circumferential direction of the radial outer side (100) of the roller (87) as the contact surface (89) for severing the subgasket (62, 93) in the direction of movement of the subgasket (62, 93).

12. Method according to claim 10 or 11, characterized in that the recess (90, 92) is designed as a preferably straight transverse slot (92) in the direction of a rotation axis (99) of the roller (87) is designed to sever the subgasket (62, 93) perpendicular to the direction of movement of the subgasket (62, 93).

13. Method according to one or more of the preceding claims, characterized in that the first and/or second subgasket (62, 63) are produced by removing a band (62, 93) as a subgasket (62) from a storage device (94) and separating individual first and/or second subgaskets (62, 63, 63) from the band (62, 93) by means of cutting with the laser beam (81).

14. Method for producing an electrochemical cell unit (53) for converting electrochemical energy into electrical energy as a fuel cell unit (1) and/or for converting electrical energy into electrochemical energy as an electrolysis cell unit (49) with stacked electrochemical cells (52), comprising the steps:

- providing layered components (5, 6, 7, 8, 9, 10, 30, 51) of the electrochemical cells (52), namely membrane electrode arrangements (6) each with a proton exchange membrane (5), a first subgasket (62, 63), a second subgasket (62, 64), an anode (7), a cathode (8) and preferably gas diffusion layers (9) and bipolar plates (10, 51),

- stacking the layered components (5, 6, 7, 8, 9, 10, 30, 51, 62, 63, 64) to form electrochemical cells (52) and a stack (65) of the electrochemical cell unit (53), characterized in that the membrane electrode assemblies (6) are provided by carrying out a method according to one or more of the preceding claims.

15. Electrochemical cell unit (53) for converting electrochemical energy into electrical energy as a fuel cell unit (1) and/or for converting electrical energy into electrochemical energy as an electrolysis cell unit (49), comprising

- stacked electrochemical cells (52) and the electrochemical cells (52) each comprise stacked layered components (5, 6, 7, 8, 9, 10, 51) and

- the components (5, 6, 7, 8, 9, 10, 51, 62, 63, 64) of the electrochemical cells (52) are membrane electrode arrangements (6) each with a proton exchange membrane (5), a first subgasket (62, 63), a second subgasket (62, 64), an anode (7), a cathode (8) and preferably gas diffusion layers (9) and bipolar plates (10, 51), characterized in that the electrochemical cell unit (53) is produced using a method according to claim 14 and/or the cut edges (67) of the first and/or second subgaskets (62, 63, 64) are fused due to thermal cutting at the cut edges (67) with a laser beam (81).