DESCRIPTION

Technical Field

The present invention relates to a plant for producing polymer electrolyte fuel cells (PEMFC) according to claim 1.

A method for producing polymer electrolyte fuel cells realised by means of the system of the present invention is also an object of the present invention.

State of the Art

Polymer electrolyte fuel cells (PEMFC) cleanly and efficiently convert the chemical energy contained in hydrogen-rich fuels (reformed gases) into high-quality electrical energy through an electrochemical process that allows to avoid the formation of pollutants. Proton exchange membrane fuel cells contain a polymer electrolyte consisting of a perfluorinated polymer containing sulphonic acid groups, two electrode layers (anode, cathode), two bipolar plates (e.g., of graphite or metallic material) and two gaskets. Specifically, the fuel cells comprise a membrane electrode assembly (MEA) comprising the polymer-catalysed membrane and two electrolyte layers (anode, cathode) supported on two gas diffusion layers (GDL), constituting the anode and cathode. The membrane separates the redox semi-reactions.

The current process envisages the production of polymer electrolyte fuel cells by means of a batch plant (or also known as with separate operating units or stations) and related process. The assembly thereof in series leads to stacks of cells which can be modulated as a function of the power required in operation.

Specifically, the known plants comprise a series of stations arranged in a factory whose connection is made indirectly by operators or robots acting on the semi-finished products, transporting them from one station to another until the final product is obtained.

The classic plants comprise production stations and related machines for carrying out the following steps of:

- depositing the sealant layer on bipolar plates by means of for example screen printing,

- drying the sealing layer;

- depositing already-compounded MEA electrode/membrane;

- Pressing the bipolar plate layers, sealant, membrane electrolyte,

- stacking the individual cells to form the desired stack.

Therefore, the known fuel cell assembly processes require further plants. Specifically, two processes and related plants are known for the production and assembly of the individual cell unit, differentiated based on how the catalytic ink is deposited. The first process consists of depositing the catalyst layer on a porous gas diffusion layer (GDL) such as graphite cloths and subsequent hot pressing together with the membrane. This first process is commonly known as catalyst-coated substrate (CCS). The second known process envisages depositing the catalyst layer directly onto the membrane. This second process is referred to as catalytic membrane (CCM). It should be noted that there are different methods for depositing the catalyser layer, such as: manual coating, ink coating and sputter deposition. Not being inserted in a continuous line, these methods require different stations and long execution times before moving on to the next movement step of the semi-finished product.

Problems of the Prior Art

The use of processes and the related batch plants used for the assembly of fuel cell stacks result in an increase in production time, which is reflected in the costs of the polymer electrolyte fuel cells.

In fact, each station of the cell assembly plant, being isolated from the others and connected only by means of robot systems and personnel, reduces productivity and increases the costs thereof. Furthermore, the stack creation times are added to those mentioned above. Specifically, such plants primarily result in an increase in the transport time of semi-finished products from one station to the next. The stationing times of the semi-finished products must then be considered, which are dependent on the assembly speed which may be subject to the incorrect passage of the semi-finished products from one station to the next.

A further disadvantage of the known processes and plants for cell assembly is the need to have separate and distinct plants for the production of the MEA unit, which increases production costs. Furthermore, it should be noted that each of the known CCS and CCM processes and plants has relative disadvantages related to the time required for proper catalyst deposition. Indeed, such processes require the sequential deposition of the catalytic layer on each surface before moving on to the next steps. Specifically, the catalyst layer is first deposited on one side of the membrane and then, at a later stage, on the opposite side of the membrane in the CCM process. In the CCS method, the catalyst is deposited on porous layers of the two electrolyte elements, which will then be assembled.

Furthermore, the catalyst deposition technologies for the production of the membrane electrolyte in turn have further disadvantages, such as inhomogeneous layer deposition.

Specifically, the manual coating requires the repetition of the coating and drying procedure to obtain the final product. This increases costs and does not ensure a fast mass production of cells. As previously mentioned, this methodology is difficult to control in terms of the deposition uniformity of the component layers, as it is affected by the manual skill and experience of the operator. Spray-coating does not reduce the catalyser load and requires frequent maintenance in order to avoid the clogging of the nozzles due to the catalyser particles. Lastly, the sputter deposition methodology envisages high installation costs related to clean rooms, Pt targets and low-pressure vacuum equipment. Furthermore, there is a high possibility of catalyst wastage if the spray gun is not correctly directed towards its target. The wastage could also be due to target reflection if the catalyst particles do not adhere to the gas diffusion layer.

Object of the Invention

The object of the present invention is to provide a plant for producing polymer electrolyte fuel cells capable of overcoming the drawbacks of the above-mentioned prior art.

In particular, it is an object of the present invention to provide a plant for producing polymer electrolyte fuel cells which is capable of reducing the production time of the cells themselves and favouring mass production, thus reducing overall manufacturing costs.

The defined technical task and the specified objects are substantially achieved by a plant for producing polymer electrolyte fuel cells comprising the technical characteristics set forth in one or more of the appended claims.

Advantages of the invention

Advantageously, the production plant of the present invention allows to reduce the production time of each polymer electrolyte fuel cell.

Advantageously, the production plant of the present invention allows mass production of polymer electrolyte fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become more apparent from the approximate and thus non-limiting description of a preferred, but not exclusive, embodiment of a plant for producing polymer electrolyte fuel cells, as illustrated in the accompanying drawings:

- figure 1 shows a schematic block view of a plant for producing polymer electrolyte fuel cells, according to an embodiment of the present invention;

- figure 2 shows a schematic block view of a plant for producing polymer electrolyte fuel cells, according to an embodiment of the present invention;

- figure 3 shows a schematic view of a polymer electrolyte fuel cell in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

Even when not explicitly highlighted, the individual features described with reference to the specific embodiments must be considered as accessories and/or exchangeable with other features, described with reference to other embodiments.

The present invention relates to a plant for producing polymer electrolyte fuel cells, preferably PEMFC, indicated overall by 1 in the figures.

For the purposes of the present invention, each polymer electrolyte fuel cell 10 comprises at least one MEA element 11, i.e., a membrane electrolyte element. Each MEA element 11 comprises electrolyte layers and a catalysed proton exchange polymer membrane, i.e., catalytic electrode layers 15. The polymer electrolyte fuel cell 10 comprises a bipolar base plate 12 and a bipolar cover plate 13. It should be noted that the MEA element is interposed between the bipolar base plate 12 and the bipolar cover plate 13. It should be noted that the catalyst used for the MEA element in the catalytic electrode layers 15 preferably consists of Pt or a Pt/Rh mixture.

Specifically, the MEA element 11 comprises a polymer electrolyte layer 14 having two opposite deposit surfaces 14a, 14b adapted to deposit catalytic electrode layers 15 comprising a cathodic and an anodic layer deposited on at least part of each deposit surface 14a, 14b and a gas diffusion layer (GDL) 16 deposited on each catalytic electrode layer 15.

Preferably, the MEA element 11 defines a multilayer structure having the polymer electrolyte layer 14 as its central layer, the catalysed cathode and anode layers as intermediate layers, i.e., the catalytic electrode layers 15 deposited on each of the deposit surfaces 14a, 14b, respectively, and as outer layers the gas diffusion layers 16, i.e., supported by the gas diffusion layers 16.

The polymer electrolyte layer 14 comprises materials based on polymers derived from perfluorosulfonic acids (PFSA) and polytetrafluoroethylene (PTFE), commercially referred to as Nafion, or non-fluorinated or partially-fluorinated polymers. Preferably, the polymer electrolyte layer 14 comprises a Nafion strip. The electrolyte layer 14 has the function of separating the redox half-reactions and has proton exchange properties. The catalytic electrode layers 15 are obtained from inks based on carbon black and organic solvent or catalyst with platinum nanoparticles mixed with carbon. The gas diffusion layer 16 is a porous support which has the function of transporting the reactant gas, distributing evenly over the electrodes and allowing a correct inflow of the electrons into the circuit. Preferably, the gas diffusion layer 16 is formed by a macroporous layer consisting of a 300- 400 pm thick carbon sheet or fabric treated with a hydrophobic agent such as polytetrafluoroethylene (PTFE) to impart hydrophobicity to the material. Furthermore, there is a microporous layer with a thickness of 10-100 pm, created by coating the macroporous layer with a mixture of carbon black (coal dust) and PTFE. The polymer electrolyte layer 14 has a thickness comprised between 10 and 100 pm of Nafion, the catalytic layer has a thickness comprised between 0.1 pm and 50pm, and the cathode and anode layers have a thickness comprised between 150pm and 405pm. The set of the catalytic layer and the electrode layer, deposited sequentially or mixed and then deposited, are indicated by 15. Lastly, the bipolar plates 12, 13 are metal or graphite-filled resin plates with a thickness between 300 pm and 2000 pm. Other used materials considered for the bipolar plates 12, 13 are: aluminium, stainless steel, conductive composite material. It should be noted that the bipolar plates 12, 13 have the dual function of evenly diffusing the fuel and oxidiser within the cell and removing the reaction products. They are connected to the external circuit and provide mechanical stability to the entire assembly [1],[2].

The pant 1 comprises a deposit line 100, configured to produce one or more of the MEA elements 11, and an assembly line 400 associated with the deposit line 100 and configured to assemble the MEA elements 11 with the bipolar plates 12, 13, obtaining the polymer electrolyte fuel cells 10.

In accordance with a preferred embodiment, the deposit line 100 and assembly line 400 are coordinated, preferably synchronized, for the production of polymer electrolyte fuel cells 10.

The deposit line 100 comprises a plurality of units for depositing (or operating stations) 20 preferably connected in series. It should be noted that the plurality of units for depositing 20 is configured to produce and move membrane electrolyte elements 11.

Preferably, the units for depositing of the plurality of units for depositing 20 are arranged adjacent to each other, i.e., in series one after the other so that the materials/semi- processed products in output from one unit for depositing continuously enter into the next unit for depositing to obtain polymer electrolyte fuel cells 10. It should be noted, in the present case, that the material can be understood as a polymer electrolyte layer such as Nafion 14, which is laid by means of related systems, as explained below. The catalytic electrode layer 15 is deposited on both sides of such a polymer layer, using, for example, additive manufacturing techniques 30. Such a semi-finished product is then heat-treated with UV/IR lamps and sent to the next station to be assembled with the two GDLs by means of a press system.

The deposit line 100 comprises movement means 200, 500, configured to continuously move the electrolyte layer 14, having two opposite deposit surfaces 14a, 14b between the operating stations. Such movement means 200, 500 are configured to continuously move the electrolyte layer 14 on which further layers are deposited. Specifically, the movement means 200, 500 have first movement means 200 and second movement means 500 arranged in series and associated with each other to move the electrolyte layer 14 as well as the related products deriving therefrom. It should be noted that the first movement means 200 and the second movement means 500 are also coordinated together with the units for depositing 20 to continuously move the electrolyte layer 14 and the related products deriving therefrom.

The first movement means 200 are configured to move the electrolyte layer 14 while keeping it tensile for the deposit of the subsequent layers. The second movement means 500 are configured to move the electrolyte layer 14 on which the other layers were deposited as well as the multilayer structure 17 i.e., the MEA element 11.

The combination of the operating stations and the movement means 200, 500 allows the MEA elements 11 to be produced in continuous flow.

It should be noted that the subsequent combination of the deposit line 100 and the assembly line 400 allows the continuous flow production of the fuel cells provided with bipolar plates, implementing a single production cycle for the production of the fuel cells 10.

It should be noted the that plant 1 envisages the production of membrane electrolyte elements 10, acting on the electrolyte layer 14 until the production of the MEA element 11 followed by assembly with the bipolar plates 12, 13.

Specifically, the first movement means 200 are configured to take the electrolyte layer 14 keeping it tensile and to move it between the plurality of units for depositing 20. It should be noted that the first movement means 200 envisage stretching the electrolyte layer 14 so that the related deposit surfaces 14a, 14b are kept taut and for transporting the semi-finished products in output from the units for depositing 20. In accordance with a preferred embodiment, the first movement means 200 comprise a plurality of rollers 210 arranged along the first production line so as to apply, preferably continuously, a tensile force on the electrolyte layer 14 to move it and keep it taut at the same time. Preferably, the first movement means 200 comprise several load cells 220 arranged in series and configured to act on the electrolyte layer 14 on both deposit surfaces 14a, 14b, so as to move it along the production line 100.

The second movement means 500 are configured to receive and transport the layers once the multilayer structures have been defined 17 as well as to transport the MEA elements 11. Preferably, the second movement means 500 comprise conveyor belts (possibly aspirated).

It should be noted that the electrolyte layer 14 has a reduced thickness with respect to the extension on the length and width dimensions, specifically the electrolyte layer 14. Preferably the reduced dimension in thickness with respect to the extension on the length and width dimensions for the electrolyte layer 14 can also be applied to the catalytic electrode 15 and gas diffusion 16 layers.

The plurality of units for depositing 20 comprise a first deposit unit 30 configured for depositing the catalytic electrode layers 15 on at least a portion of each deposit surface 14a, 14b of the electrolyte layer 14. Specifically, the first deposit unit 30 is configured to deposit at least one catalytic electrode layer 15 on the deposit surfaces 14a, 14b. In detail, the first deposit unit 30 is configured to continuously deposit a catalytic electrode layer 15 on the surfaces 14a, 14b of the electrolyte layer 14, which is moved by the first movement means 200.

In accordance with a preferred embodiment, the first deposit unit 30 is configured to deposit the catalytic electrode layers 15 simultaneously on each of the deposit surfaces 14a, 14b of the electrolyte layer 14. Specifically, the first deposit unit 30 is configured to deposit a catalytic electrode layer 15 on both deposit surfaces 14a, 14b as the electrolyte layer 14 passes through the relative unit. Such depositing preferably takes place in a continuous flow so as to reduce production times.

Preferably, the first deposit unit 30 is configured to deposit the catalytic electrode layers 15 symmetrically on each deposit surface 14a, 14b of the electrolyte layer 14. Specifically, the first deposit unit 30 is configured to deposit the catalytic electrode layers 15 on deposit areas of the deposit surfaces 14a, 14b which are symmetrical with respect to the electrolyte layer itself 14. In detail, the first deposit unit 30 is configured to symmetrically produce a semi-finished product comprising the electrolyte layer 14 in the centre and symmetrical catalytic electrode layers 15 on the deposit surfaces 14a, 14b.

In accordance with a preferred embodiment illustrated in figure 1, the first deposit unit 30 is configured to deposit each catalytic electrode layer 15 by means of ink-jet printing. Preferably, the first deposit unit 30 envisages ink-jet printing a catalytic electrode layer 15 on both deposit surfaces 14a, 14b. In accordance with the present embodiment, the first deposit unit 30 comprises ink-jet printing devices 31, where each ink-jet device is associated with a deposit surface 14a, 14b. Thereby, the simultaneous and preferably symmetrical printing of the catalytic electrode layers 15 on each deposit surface 14a, 14b is made possible.

In accordance with an alternative embodiment to the previous one, illustrated in figure 2, the first deposit unit 30 is configured to deposit each catalytic electrode layer 15 by means of rotary printing 32. Preferably, the first deposit unit 30 envisages rotary printing a catalytic electrode layer, preferably by means of flexograpy or screen printing on both deposit surfaces 14a, 14b. In accordance with the present embodiment, the first deposit unit 30 comprises rotary printing devices 32 where each device is associated with a deposit surface 14a, 14b. Thereby, the simultaneous and preferably symmetrical printing of the catalytic electrode layers 15 on each deposit surface 14a, 14b is made possible.

The plurality of units for depositing 20 comprises a second deposit unit 40 configured for depositing on each electrolyte deposit surface 14a, 14b gas diffusion layers

16 at least on the deposited catalytic electrode layers 15, defining multilayer structures 17. The second deposit unit 40, located downstream of the first deposit unit 30, receives the semi-finished product in input coming from the previous units along the deposit line 100. Preferably, the second deposit unit 40 is configured to deposit the gas diffusion layer 16 on each electrolyte surface 14a, 14b to cover at least the catalytic electrode layers 15. More preferably, the second deposit unit 40 is configured to deposit the gas diffusion layer 16 on each electrolyte surface 14a, 14b to cover at least the catalytic electrode layers 15 continuously. Specifically, as the electrolyte layer 14 passes with the catalytic electrode layers 15 in the second deposit unit 40, the second deposit unit 40 continuously deposits the related gas diffusion layers 16.

It should be noted that the multilayer structures 17 comprise the electrolyte layer 14, the catalytic electrode layers 15 and the gas diffusion layers 16. The multilayer structure

17 has a thickness comprised between 160pm and 555pm. In accordance with a preferred embodiment, the second deposit unit 40 is configured to deposit, simultaneously on each of the deposit surfaces 14a, 14b of the electrolyte layer 14, the gas diffusion layer 16 on the previously deposited catalytic electrode layers 15. Specifically, the second deposit unit 40 is configured to deposit the gas diffusion layers 16 on both deposit surfaces 14a, 14b to at least cover the catalytic electrode layers 15 during passage of the electrolyte layer 14 in the relevant unit.

Preferably, the second deposit unit 40 is configured to deposit gas diffusion layers 16 symmetrically on each deposit surface 14a, 14b of the electrolyte layer 14 at least on the catalytic electrode layers 15. Specifically, the second deposit unit 40 is configured to deposit the gas diffusion layers 16 at least on the deposit areas of the symmetrical deposit surfaces 14a, 14b with respect to the electrolyte layer 14 itself where the catalytic electrode layers were deposited. In detail, the second deposit unit 40 is configured to symmetrically produce a semi-finished product comprising the electrolyte layer in the centre and symmetrical catalytic electrode layers 15 assembled to the corresponding gas diffusion layers 16 on the deposit surfaces 14a, 14b.

In accordance with a preferred embodiment, the second deposit unit 40 is configured to deposit the gas diffusion layers 16 by unwinding and compressing the gas diffusion layers 16 on both deposit surfaces 14a, 14b, to cover at least the deposited catalytic electrode layers 15.

Preferably, the second deposit unit 40 comprises unwinding devices 41 configured to unwind the gas diffusion layers 16 on each deposit surface 14a, 14b and calendering devices 42 configured to compress the layers 14, 15, 16 together. Specifically, the unwinding devices 41 associated with the calendering devices 42, are configured to unwind the gas diffusion layers 16 upon the passage of the electrolyte layer 14 on which the catalytic electrode layers 15 have been deposited. Preferably, the calendering devices 42 are configured to receive in input the electrolyte layer 14 with the catalytic electrolyte layers 15 and the gas diffusion layers 16 associated with each deposit surface 14a, 14b to cover at least the catalytic electrodes 15. In detail, the calendering devices 42 apply a compression force between the layers in input to compress them together and define the multilayer structure 17, as well as a tensile force to facilitate the exit of the multilayer structure from the calendering zone. It should be noted that the unwinding devices 41, which are arranged upstream of the calendering devices 42, are necessary to ensure that the layers are deposited evenly and preferably continuously.

In accordance with a preferred embodiment, the first deposit unit 30 is configured to continuously deposit the catalytic electrode layers 15, spaced from each other by a spacing portion, on each deposit surface 14a, 14b of the electrolyte layer 14. Specifically, each catalytic electrode layer 15 is surrounded by a spacing portion of electrolyte layer 14. Alternatively, the first deposit unit 30 is configured to continuously deposit the electrode layers 15 on each deposit surface 14a, 14b of the electrolyte layer 14, comprising substantially the entire deposit surface 14a, 14b of the electrolyte layer 14 or leaving an outline portion at the side edges of each deposit surface 14a, 14b. In a further embodiment, the catalytic electrode layers 15 are deposited on the deposit surfaces, covering them entirely. In accordance with the aforementioned embodiments of depositing the catalytic electrode layers 15, the second deposit unit 40 is configured to cover the catalytic electrode layers 15, spaced apart from each other by the separation portions, with the gas diffusion layers 16 or to cover the entire deposit surfaces 14a, 14b at less than the outline position or to cover the entire deposit surfaces 14a, 14b.

The plurality of units for depositing 20 comprises a separation unit 50, configured to separate the multilayer structures 17 from each other to produce MEA elements 11. Specifically, the separation unit 50, arranged downstream of the second deposit unit 40, is configured to separate the produced multilayer structures 17 from each other, which is receives as semi-finished products from the previous units. The separation can occur by separating the multilayer structures 17, acting on the electrolyte layer 14, optionally on the gas diffusion layer 16 at the separation portions. Alternatively, the separation between the multilayer structures 17 can occur by acting directly on the multilayer structure and the outline portion.

The multilayer structures 17 exiting from the second deposit unit 40 are then moved by the second movement means 500, e.g., conveyor belts connecting the second deposit unit 40 on the calendering side with the separation unit 50. That is, the second movement means 500 allow the entry of the multilayer structure 17 into the separation unit 50 to produce MEA elements 11.

In accordance with a preferred embodiment, the separation unit 50 is configured to separate the multilayer structures 17 from each other by means of cutting at least the electrolyte layer 14. Specifically, the electrolyte layer 14 being the base on which the other layers are deposited in the separation step needs to be cut in order to divide the multilayer structures 17 from each other. In accordance with the previously described embodiments for depositing, the separation unit 50 is configured to cut the electrolyte layer 14 and optionally the gas diffusion layer 16 at the separation portions. Alternatively, the separation unit 50 is configured to cut the entire multilayer structure 17 and/or electrolyte layer 14 and optionally the gas diffusion layer 16 at the outline portions.

It should be noted that the separation unit 50 is configured to act on the semi-finished product in output from the second deposit unit 40 transported by the second movement means 500.

Preferably, the separation unit comprises one or more laser cutting devices 51 configured to separate the multilayer structures 17, obtaining MEA elements 11 of the desired dimensions.

Following the cutting step , the MEA elements produced 11 are transferred to the assembly line 400 by means of a movement unit 60. Specifically, the plurality of units for depositing comprises the movement unit 60 configured to move each MEA element 11 produced to the assembly line 400. Specifically, the movement unit 60 is configured to move the MEA elements 11, i.e., the produced elements from the deposit line 100, to the assembly line 400. Specifically, the movement unit 60 is configured to take the MEA elements 11 from the separation unit 50 and move them to the assembly line 400, preferably in a continuous manner. Thereby, the plant allows the continuous production of fuel cells 10.

In accordance with a preferred embodiment, the movement unit 60 comprises automated means, e.g., industrial robots, configured to take the MEA elements 11 from the separation unit and move them to the assembly line 400. It should be noted, as explained below, that the deposit line 100 and the assembly line 400 are synchronized so as to produce the fuel cells 10 in a continuous flow. Specifically, the movement unit 60 is synchronized with the assembly line 400 to position each MEA element 11 produced between two bipolar plates 12, 13 so as to produce polymer electrolyte fuel cells 10.

In accordance with a preferred embodiment, the plurality of units for depositing 20 comprises a first storage unit 70 arranged upstream of the first deposit unit 30 configured for the storage of the electrolyte layer 14, e.g., Nafion, and preferably for the related tensioning. The first storage unit 70 comprises an unwinder 71 where the electrolyte layer 14 is stored, e.g., by means of a coil positioned on the unwinder 71. Specifically, the first movement means 200 are configured, preferably together with the first storage unit 70, to take the electrolyte layer 14 from the first storage unit 70 to allow the tensile transport in the first deposit unit 30 for the proper depositing of the layers. For the purpose of a correct depositing of the catalytic electrode layers 15, the first movement means 200 comprise centring elements 230, arranged along the assembly line 100, configured to allow a correct centring of the electrolyte layer 14.

More preferably, a pre-treatment unit 2 is arranged upstream of the deposit unit 30, for treating the deposit surfaces 14a, 14b to improve the adhesion and surface tension properties of the electrolyte 14. Such a treatment, for example, is the 'crown' treatment.

In accordance with a preferred embodiment, the plurality of units for depositing 20 comprises a treatment unit 80 arranged between the first deposit unit 30 and the second deposit unit 40. The treatment unit 80 is configured to perform a fixing treatment of the catalytic electrode layers 15, which are deposited on the related deposit surfaces 14a, 14b. Specifically, the treatment unit 80 is configured to act on the deposited catalytic electrode layers 15, preferably simultaneously on both deposit surfaces 14a, 14b so as to fix the layers themselves on the electrolyte layer 14. The treatment unit 80 is configured to continuously treat the electrolyte layer 14 passing in the first deposit unit 30 on which the catalytic electrode layers 15 have been deposited.

Preferably, the treatment unit 80 is configured to fix the ink following the printing step performed at the first deposit unit 30. Specifically, the treatment unit 80 is configured to perform a curing treatment on the deposited catalytic electrode layers 15. For example, the treatment unit 80 can comprise UV-fixing devices or IR- fixing devices 81 acting on each deposit surface 14a, 14b of the electrolyte layer 14, on which the catalytic electrode layers 15 have been deposited so as to fix them to each other.

In accordance with a preferred embodiment, the plurality of units for depositing 20 comprise a tensioning unit 90, arranged between the second deposit unit 40 and the separation unit 50, configured to facilitate the extraction of the multilayer structures 17, generating a tensile force for the movement thereof. The tensioning unit 90 can comprise, for example, devices for aspirated tensioning 91. Such aspirated tensioning devices 91 can then be associated with the movement means 500 so as to continuously transport the products in output from the second deposit unit 40.

In detail, the deposit line 100 allows one or more layers to be deposited sequentially on the electrolyte layer until the elements are produced by separation

The deposit line 100 has a production rate of MEA elements 11 preferably comprised between one and twenty-five elements per minute (as a function of cell size and geometry).

The assembly line 400 is configured to receive in input the MEA elements 11 in order to assemble them with the relative bipolar plates 12, 13 to produce the PEM fuel cells 10. Specifically, the assembly line 400 is synchronized with the movement unit 60 and with the deposit line 100 to receive the MEA elements 11 on the bipolar base plate 12 to be subsequently assembled with the bipolar cover plate 13.

In accordance with a preferred embodiment, the plurality of assembly units 300 comprises a coordination unit 310 associated with the movement unit 60, configured to receive each produced MEA element 11 on the bipolar base plate 12. Specifically, the coordination unit 310 is configured to move the bipolar plates 12, 13 and receive each produced MEA element 11 on bipolar base plates 12. Preferably, the coordination unit 310 is synchronized with the movement unit 60 so that the movement of the MEA elements 11 coincides with the position of the bipolar base plate 12. Specifically, the movement unit 60 is configured to take the MEA elements 11 from the separation unit 50 and deposit them on a deposit position 600 on the assembly line 400, preferably at a moved bipolar base plate 12. The coordination unit 310 is configured to move the bipolar plates 12, 13 so that the base bipolar plate 12 is in the deposit position 600 to receive the MEA element 11. Thereby, the coordination unit 310 allows the membrane electrolyte elements 11 to be positioned on the relative bipolar base plate 12. Preferably, the coordination unit 310 comprises a conveyor belt 700 configured to move the bipolar plates 12, 13 coordinated with the movement unit 60 to position the MEA elements 11 on the relative bipolar base plate 12.

More preferably, the plurality of assembly units 300 comprises a second storage unit 350 associated with the coordination unit 310 and configured to conserve the bipolar plates 12, 13. Specifically, coordination unit 310 is configured to receive the bipolar plates 12,13 from the second storage unit 350.

In accordance with a preferred embodiment, the plurality of assembly units 300 comprises a closing unit 320 configured to position the bipolar cover plates 13 on the bipolar base plates 12 containing the MEA elements 11. Specifically, the closing unit 320 is configured to take a bipolar cover plate 13 from the coordination unit 310, preferably from the conveyor belt, and position it on a bipolar base plate 12 where the MEA element 11 has already been positioned. Thereby, the closing unit 320 allows the PEM fuel cell 10 to be assembled. It should be noted that the closing unit 320 can be arranged in parallel or in series with the coordination unit 310.

Preferably, the closing unit 320 comprises robotic closing devices 321 configured to take closing plates 13 from the coordination unit 310, preferably from the conveyor belt 700 and place them on bipolar base plates 12 provided with the MEA element 11.

In accordance with a preferred embodiment, the plurality of assembly units 300 comprises a pressing unit 330 configured to compress the bipolar plates 12, 13 and the MEA element 11 together so as to produce polymer electrolyte fuel cells 10. It should be noted that the pressing unit 330 is arranged downstream of the coordination unit 310 and is configured to receive the membrane electrolyte element 11 interposed between the bipolar plates 12, 13 so as to compress and fix the bipolar plates 12, 13 and the membrane electrolyte element 11 together. Preferably, the pressing unit 330 comprises hot pressing devices 331 for performing a compression of the MEA element 11 between bipolar plates 12, 13. The pressing, i.e., sealing, step operates in a pressure range comprised between 500 and 1500 Psi, a temperature range between 50 and 150°C and a time comprised between 1 and 15 minutes.

In accordance with a preferred embodiment, the plurality of assembly units 300 comprises a third deposit unit 340 configured to deposit sealing elements 18 in defined sealing areas 19 on the bipolar base plate 12. Such sealing areas 19 are defined on the bipolar base plate 12. Preferably, the coordination unit 310 is configured to position the membrane electrolyte element 11 within the sealing area 19 by synchronizing with the movement unit 60 in the manner described above, coordinating both the deposit position 600 and the sealing area 19 for the membrane electrolyte element 11.

In accordance with a preferred embodiment, the third deposit unit 340 is configured to deposit sealing elements 18 also on the bipolar cover plate 13 in the sealing areas 19 defined on the bipolar cover plate 13. In this case, the closing unit is configured to position the bipolar cover plate 13 on the bipolar base plate 12 so that the sealing areas 19 are overlapping and delimit the MEA element 11.

Preferably, the third deposit unit 340 is configured to deposit sealing elements 18 by means of ink-jet or flat screen printing or 3D printing with an extruder.

Preferably, the deposit line 100 has a PEM cell 10 production rate comprised between one and five cells per minute (as a function of cell size and geometry).

Preferably, the plant 1 comprises a control system associated with the deposit line 100 and the assembly line 400 and the related line units as well as the movement means 200, 500. Such a control system is configured to manage and control the production of the PEM fuel cells 10. Specifically, the control system coordinates the movement of the electrolyte layer 14, the MEA elements 11 and the bipolar plates 12, 13 and the activation of the different units for producing the membrane electrolyte elements 11 and the assembly of the cells 10.

It should be noted that the units for depositing 20 arranged in series along the deposit line 100 are sequentially fed by the first movement means 200 with the electrolyte layer 14 and subsequently to the layer deposits by the second movement means 500. Each deposit unit 20 sequentially receives the electrolyte layer 14 taken and the semi-finished products from the previous unit (i.e., the electrolyte layer on which the layers were deposited and then fixed). Such units for depositing 20 are intended to be one after the other so as to reduce the processing time and the transition to the next. Furthermore, the assembly line 400 is arranged in series with respect to the deposit line 100, receiving the MEA elements 11 in input to then sequentially produce the PEM fuel cells 10.

In accordance with a preferred embodiment, the plant 1 is configured to produce polymer electrolyte fuel cell stacks. Specifically, a stack can comprise two or more overlapping polymer electrolyte fuel cells sharing a bipolar plate. In detail, each polymer electrolyte fuel cell overlapped to form a stack shares a bipolar plate with the adjacent cell along an overlapping direction. In other words, the bipolar plate between two cells is in common. In this embodiment, the plurality of assembly units 300 comprises picking and movement means (not illustrated) configured to take the product in output from the pressing unit 330, e.g., a polymer electrolyte fuel cell 10 or a stack of two or more cells, and transport it to the coordination unit 310. In the present embodiment, the coordination unit 310 is therefore also configured to move products of the pressing unit 330 like cells and/or stacks. It should be noted that the operation of the assembly units 300 and the related assembly line 400 is similar to that described above, with one of the bipolar base plates 12 being replaced by one of the bipolar plates of the product moved by the picking and movement means in output from the pressing unit 330. Therefore, the coordination unit is configured to move stacks or cells to place a produced MEA element 11 on the exposed bipolar plate of the cell or stack. In detail, the picked product replaces a bipolar base plate of the previous embodiment so as to deposit the MEA element on the exposed plate and place a bipolar cover plate above such a bipolar plate. Thereby, the pressing unit 330 is configured to compress the bipolar cover plate and the cell or stack together to produce a two-cell stack or a stack with more than two cells. It should also be noted that the same actions carried out on the bipolar plates of the previous embodiment can be carried out on the bipolar plate of the cell or stack and the related bipolar cover plate. It should therefore be noted that in accordance with the present embodiment, one of the bipolar plates of the cell or cell stack in output from the pressing unit acts as the base bipolar plate, as in the previous embodiment, and the plant in terms of units acts on such a bipolar plate as if it were the base bipolar plate of the previous embodiment.

A further object of the present invention is a method for producing polymer electrolyte fuel cells 10, each comprising an MEA element 11 interposed between a bipolar base plate 12 and a bipolar cover plate 13. It should be noted that the method is implemented by means of the plant described above.

The method comprises a series of steps performed continuously by means of movement of the electrolyte layer with the movement means 200, 500 and coordination with the plurality of assembly units 300.

It should therefore be noted that each step of the method can be punctuated from the next by an intermediate movement step of the electrolyte layer 14 for the deposit line 100 and an intermediate movement step of the bipolar plates 12, 13 and/or membrane electrolyte elements 11 for the assembly line 400. Such intermediate movement steps preferably occur from one plant unit to the next (and/or the previous one).

In accordance with a preferred embodiment, the method comprises the steps of providing a deposit line 100 comprising a plurality of deposit units 20 in series configured to deposit further layers on the electrolyte layer 14 producing MEA elements 11. The deposit line 100 provided also comprises movement means 200, 500 configured to move an electrolyte layer 14 having two opposite deposit surfaces 14a, 14b between the units for depositing 20. Preferably, the plurality of units for depositing 20 comprise a first deposit unit 30, a second deposit unit 40, a separation unit 50 and a movement unit 60 having the functions and characteristics described above. More preferably, the plurality of units for depositing 20 can also comprise a first storage unit 70, a treatment unit 80 and a tensioning unit 90 and a pre-treatment unit 2 having the functions and characteristics described above. It should be noted that the step of providing the deposit line 100 envisages providing the related units and movement means 200, 500 in accordance with the preferred embodiments. Such units are arranged in series in the manner described above.

The movement means 200, 500 provided are configured to connect the units for depositing 20 in series, moving the electrolyte layer 14 therebetween. Specifically, the movement means 200, 500 have first 200 and second 500 movement means. In detail, the first movement means 200 are configured to move the electrolyte layer between the first deposit unit 30 and the second deposit unit 40, while the second movement means are configured to move the electrolyte layer 14 on which the layers were deposited, from the outlet of the second deposit unit 40 to the movement unit 60.

The method comprises a step of providing an assembly line 400 associated with the deposit line 100 by means of the movement unit 60 and comprising a plurality of assembly units 400. Preferably, the plurality of assembly units 400 comprises a coordination unit 310, a closing unit 320, and a pressing unit 330 having the functions described above. More preferably, the plurality of assembly units 400 can comprise a third deposit unit 340 and a second storage unit 350 having the functions described above. It should be noted that the step of providing the assembly line 300 envisages providing the related units in accordance with the preferred embodiments.

In accordance with a preferred embodiment, the method comprises a preliminary step of unwinding the electrolyte layer 14 between the plurality of units for depositing 20 at least up to the second deposit unit 40. Preferably, the method envisages keeping the electrolyte layer 14 tensile between the units at least until the separation of the multilayer structures 17. More preferably, the method envisages surface treatments of the deposit surfaces of the electrolyte layer along the deposit line 100.

The method comprises a step a) of depositing by means of the first deposit unit 30 the catalytic electrode layers 15 on each deposit surface 14a, 14b of the electrolyte layer 14. Step a), carried out by means of the first deposit unit 30, envisages the deposit of the catalytic electrode layers 15 on each deposit surface 14a, 14b preferably on the portion of the electrolyte layer 14 present within the unit itself. The catalytic electrode layers 15 are simultaneously deposited on both deposit surfaces 14a, 14b, preferably symmetrically with respect to the electrolyte layer 14. Specifically, the first deposit unit 30 envisages the deposition of the catalytic electrode layers 15 along a direction perpendicular to the deposit surfaces 14a, 14b on both deposit surfaces 14a, 14b. In accordance with a preferred embodiment, step a) envisages depositing the catalytic electrode layers 15 by means of ink- jet printing or rotary screen printing or flexograpy. Step a) produces a semi-finished product to be sent to the subsequent units for producing the MEA elements 11.

The deposit step a) is carried out continuously on the deposit surfaces of the electrolyte layer passing through the first deposit unit 30.

In accordance with a preferred embodiment, the method envisages a treatment step for fixing the catalytic electrode layers 15 by means of a treatment unit downstream of the first deposit unit 30. Thereby, the catalytic electrode layers 15 are fixed to the electrolyte surfaces 14 and are arranged for the subsequent steps.

Subsequently, the method comprises the step b) of continuously depositing the gas diffusion layer 16 on each deposit surface 14a, 14b by means of the second deposit unit 40. Adhering to the catalytic electrode layers 15, the gas diffusion layer 16 defines the multilayer structures 17. Step b) envisages depositing the gas diffusion layers 16 on each deposit surface, covering the catalytic electrode layers 15 for producing multilayer structures 17. Such multilayer structures 17 can be separated by separation portions or surrounded by outline portions at the edges of the deposit surfaces or entirely covering the deposit surfaces.

Preferably, step b) envisages depositing the gas diffusion layers 16 by compression by means of calendering on the catalytic electrode layers 15. More preferably, step b) envisages simultaneously depositing gas diffusion layers on both deposit surfaces. Even more preferably, step b) envisages depositing the gas diffusion layers 16 simultaneously and symmetrically with respect to the electrolyte layer.

It should be noted that steps a) and b) envisage acting on the same electrolyte layer 14 so that each unit for depositing 20 acts on the related deposit surfaces processed by the previous unit. Preferably, steps a) and b) are carried out by means of the coordinated and synchronized transport of the electrolyte layer by the first movement means 200 and preferably by the tensioning means 90.

In accordance with a preferred embodiment, the method envisages a tensioning step by means of the tensioning unit 90 downstream of the second deposit unit 40. The tensioning step envisages facilitating the extraction of the layers from the second deposit unit 40. More preferably, the second movement means 500 allow together with the tensioning unit 90 to extract the product from the second deposit unit 40.

It should be noted that the steps of depositing layers are performed on the surface facing the external environment. Specifically, electrolyte layer 14 has the two opposite deposit surfaces. The subsequent layers deposited on the electrolyte layer 14 will have relative surfaces facing the deposit surface of the previous layer and opposite deposit surfaces up to the gas diffusion layer where the deposit surface is free and facing the external environment.

The method comprises a step c) of separating the multilayer structures 17 by means of the separation unit 50, producing MEA elements 11. Specifically, step c) envisages acting on the produced multilayer structures 17 so as to separate them to produce MEA elements 11. As described above in the plant, step c) envisages cutting at least the electrolyte layer 14 between the multilayer structures, optionally also the gas diffusion layer 16 and the catalytic electrolyte layers 15. In detail, step c) envisages producing a fuel cell component.

It should be noted that step c) and the steps carried out up to the movement unit 60 are carried out by means of movement with the second movement means 500 of the product in output from the second deposit unit 40.

In accordance with a preferred embodiment, the method comprises a movement step by means of the movement unit 60 for moving the MEA elements 11 from the deposit line 100 to the assembly line 400.

It should be noted that the assembly line 400 and the deposit line 100 are coordinated as a function of the membrane electrolyte elements 11 produced.

The method comprises a step d) of assembling each MEA element 11 with the bipolar plates 12, 13 by means of the plurality of assembly units 300 for producing polymer electrolyte fuel cells 10. Specifically, step d) envisages receiving the MEA elements 11 and arranging them between the bipolar plates 12, 13 so as to produce the polymer electrolyte fuel cells 10. In accordance with a preferred embodiment, step d) comprises a step dl) of placing membrane electrolyte elements 11 on the bipolar base plates 12 by means of the coordination unit 310. Such a coordination unit 310 moves the bipolar plates 12,13 so as to correctly receive ME A elements 11 on the relative bipolar plate 12. The coordination unit 310 is synchronized with the movement unit 60 to position and receive MEA elements 11 on the relative bipolar base plate 12. Specifically, step dl) envisages moving the bipolar base plate 12 in the deposit position 600 to place the MEA element 11. Step d) comprises step d2) placing the bipolar cover plate 13 on the bipolar base plate 12 on which the MEA element 11 was placed. Lastly, step d) comprises a step d3) of compressing the bipolar plates 12, 13 and the relative MEA element 11 arranged therebetween so as to produce the polymer electrolyte fuel cell 10. Preferably, step d3) envisages compressing and heat- treating the bipolar plates 12, 13 and the MEA elements 11 to produce the polymer electrolyte cell 10 by means of the related pressing unit 330.

In accordance with a preferred embodiment, step d) comprises a preliminary step of picking the bipolar plates 12, 13 from the second storage unit 350 and placing them in the coordination unit 310.

In accordance with a preferred embodiment, step d) comprises an intermediate sealing step by means of the third deposit unit 340 which deposits sealing elements 18 on the bipolar base plate 12, preferably also on the bipolar cover plate 13. Specifically, the intermediate step envisages the definition of sealing areas 19.

The assembly steps are performed in succession so that the outer surfaces of the MEA element 11 face the relative surfaces of the bipolar plates 12, 13.

The method comprises the step of continuously performing steps a)-d), coordinating the deposit line 100 and assembly line 300. It is thereby possible to continuously produce the polymer electrolyte fuel cells 10. In accordance with the preferred embodiment for producing stacks, step d) envisages a step of picking the product in output from the pressing unit, e.g., a cell or a stack, and placing the product on the coordination unit. Thereby, step d) envisages acting on the bipolar plate of the cell or stack exposed for processing as if it were the bipolar base plate of the previously described embodiment. Specifically, step d) envisages moving the plates, the cell and/or the stack, depositing the MEA element, carrying out any sealing, positioning the bipolar cover plate and compressing with relative heat treatment to produce cell stacks. Such a step can be repeated according to the present embodiment on new cells produced, thus producing stacks of two cells, or acting on cell stacks to increase the relative cells associated with a stack.

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