WO2024134002A1 - Method for obtaining a membrane electrode assembly (mea) unit in electrochemical devices - Google Patents

Method for obtaining a membrane electrode assembly (mea) unit in electrochemical devices Download PDF

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Publication number
WO2024134002A1
WO2024134002A1 PCT/ES2023/070769 ES2023070769W WO2024134002A1 WO 2024134002 A1 WO2024134002 A1 WO 2024134002A1 ES 2023070769 W ES2023070769 W ES 2023070769W WO 2024134002 A1 WO2024134002 A1 WO 2024134002A1
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Prior art keywords
membrane
mea
electrodes
assembly
bar
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PCT/ES2023/070769
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Spanish (es)
French (fr)
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Jadra MOSA RUÍZ
Carmen DEL RÍO BUENO
Pilar GARCIA ESCRIBANO
Mario Aparicio Ambros
Desirée RUIZ GARCÍA
Ángel TRIVIÑO PELÁEZ
Eva CHINARRO MARTÍN
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Consejo Superior De Investigaciones Científicas (Csic)
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Publication of WO2024134002A1 publication Critical patent/WO2024134002A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • MEA membrane-electrode assembly unit
  • the present invention refers to a procedure for obtaining a membrane-electrode assembly unit (MEA, Membrane Electrode Assembly) for electrochemical devices such as fuel cells, ion exchange electrolyzers, redox flow batteries and other storage systems. generation or storage of energy, which allows assembly when the membrane used is not purely polymeric in nature (non-commercial) and improves assembly when it is.
  • This new procedure includes a pre-pressing stage that facilitates the assembly between the components and improves the interfaces, facilitating their handling, improving their efficiency in the stack and their post-mortem analysis.
  • the invention can be framed in the area of materials science and energy, and is of interest to industries that manufacture electrochemical components, as well as small electronic or biomaterial devices.
  • MEA membrane-electrode assembly unit
  • the proton exchange membrane acts as an electrolyte, transporting the protons generated in the anode to the cathode and also as a separator between both electrodes.
  • AEMFC anion exchange fuel cells
  • the membrane is a conductor of hydroxyl anions. Therefore, the requirements that the membrane must have in these devices are: to have a high ionic conductivity, to be electronic insulator and impermeable to both fuel and oxygen. Likewise, it must be chemically and mechanically resistant under the operating conditions of the cell and, finally, it must be obtainable at low cost in the form of thin films.
  • sSEBS sulfonated styrene-ethylene-butylene-styrene
  • membranes with styrene groups are graft polymers based on a hydrophobic and stable main chain to which sulfonated polystyrene chains are grafted, and, on the other hand, there are membranes based on polymers with aromatic groups in the main chain such as They are polysulfones and polyether ether ketones;
  • Other membranes are based on sulfonated polyphosphazenes, sulfonated polyimides, especially naphthalene ones, as well as polybenzimidazole membranes doped with phosphoric acid.
  • Hybrid membranes can be classified into two main groups based on the nature and strength of the interaction between both components.
  • class I which consist of an ionomeric matrix in which inorganic particles, generally of nanometric size, are dispersed
  • class II forces where the interaction between the components is at a molecular level so both must include in their structure functional groups capable of reacting with each other to form chemical bonds, usually synthesized by sol-gel) whose bonds are covalent or ionic-covalent.
  • the border between both classes is blurred and there may be systems with characteristics of both groups.
  • the MEA unit is the central component of an ion exchange membrane fuel cell (or electrolyzer).
  • ion exchange membrane fuel cell or electrolyzer.
  • different strategies have been designed, such as improving the fragility of the gas diffusion layer through the addition of polymers such as Teflon® or the use of fabrics instead of paper. coal; also through new processing such as roll to roll or other industrial processing commonly used in the polymer materials industry.
  • Much research has also been carried out to improve the catalytic ink that is deposited on the gas diffusion layer, both in the synthesis of the ink itself and in the method used for its deposition.
  • various temperature and pressure parameters have been described for the component assembly stage by hot pressing.
  • the limiting factor in most hot-pressed membrane-electrode assemblies is the ease with which tensions can be created, especially at the edges of the active area and even more so at the points through which the gases are fed, facilitating the formation of microcracks that lead to lower battery performance and can even end up short-circuiting the system.
  • the methods of preparing MEA units are grouped into two techniques [J. Zhao; S. Shahgaldi; A. Ozdenlbrahim; E. Alaefour; X. Li; F. Hamdullahpu, Effect of catalyst deposition on electrode structure, mass transport and performance of polymer electrolyte membrane fuel cells, Applied Energy 255 (2019) 113802], depending on the substrate on which the catalytic layer is deposited. 1) When the catalytic layer is deposited on the gas diffusion layer GDL (Gas Difussion Layer), the method is called CCS (Catalyst Coated on Substrate) or also the GDE method (Gas Difussion Electrode) [ AND. López-Fernández; C.
  • the MEA is placed in the measurement cell normally between two seals to prevent gas leaks and short circuits between the bipolar and/or terminal plates.
  • the present invention refers to a procedure for obtaining a key part in fuel cells and low temperature electrolyzers such as the membrane-electrode assembly, the MEA unit.
  • the new procedure is a special advantage when the membrane is of an inorganic or organic-inorganic hybrid nature with a high content of non-polymehco component, which show greater fragility, which makes its assembly and handling difficult.
  • the procedure described in the present invention is of special interest for the end user, for industries that manufacture fuel cells and/or electrolyzers, energy storage devices and transportation industries (both domestic and aeronautical, naval, railway) as well as small electronic devices. It can also be useful in the manufacture of redox flow batteries and in their different applications. On the other hand, you may have interest in companies that manufacture gas diffusion layers or catalysts.
  • the present invention refers to a procedure for obtaining an MEA unit (membrane-electrode assembly) through laminating and pressing processes (hereinafter "method of the invention") that comprises the following steps: a) preheat a laminator that has a roller release system, for at least 4 minutes at a temperature between 75 e C and 125 e C; b) hole a plastic cover (1) at its midpoint making a window (2) with the measurement of the desired active area for the MEA unit; c) placing a membrane (3) inside the plastic cover of step (b), constituting the cover-membrane assembly; d) cover the sheath-membrane assembly obtained in (c) with onion-type protective paper; e) laminate with the preheated laminator from step (a) the cover-membrane assembly obtained in (d) at a temperature between 75 and 125 e C; f) manually remove the onion-type protective paper from the laminated product obtained in (e), leaving the laminated membrane; g
  • the laminator must have a roller release system (two or four) to avoid possible jams that could damage the cover-membrane assembly.
  • the use of onion paper or similar is intended to cover the sheath-membrane assembly to facilitate passage through the laminator rollers without causing jams, thus avoiding damage during laminating.
  • the laminating must seal the membrane respecting its dimensionality with respect to the laminating sheath used.
  • the temperature of the process can oscillate depending on the thickness of the assembly, where for thicknesses of 80 pm the temperature is 75 e C and for greater thicknesses it can reach up to 125 e C.
  • the electrode must always slightly overlap the laminate window.
  • the size of the electrodes is 2.24 x 2.24 cm 2
  • the size of the active area has to be slightly smaller, in this preferred example 2.15 x 2.15 cm 2 , reducing the active area by 7.8% .
  • the procedure of the present invention has numerous advantages such as that the MEA unit obtained is well assembled, with all the components joined together and after the test in the pile its dimensionality does not change, thus allowing post-mortem tests to be carried out that can help to understand the operation of the MEA unit or repeat the electrochemical characterization later if necessary.
  • Another advantage of the procedure of the invention would be that the experimental pressing conditions can be lowered in step (h) regardless of the nature of the membrane used, both temperature, pressure and time, avoiding softening and fluidity processes of the membrane. , as well as structural damage.
  • step (e) facilitates contact between the membrane-electrode interfaces, improving efficiency in the stack with respect to membranes assembled by the conventional hot pressing method.
  • step (e) allows the manufacture of the MEA unit, its handling, as well as successive assembly and disassembly processes for the repetition of electrochemical tests. This processing method facilitates the incorporation of up to 50% inorganic content into the hybrid membrane.
  • onion paper is understood as any vegetable paper that, like tissue paper, is exceptionally light and thin; translucent and flexible with satin texture. Although thin, it is extremely strong due to its uniform fiber formation and 25% cotton fiber content, allowing for large suitable folding properties.
  • a previous stage of preparation of the components of the MEA unit, the membrane (3) and the electrodes (4a and 4b), is carried out to the desired size, and by a method CCS or a CCM method.
  • the preparation of the components of the MEA unit is understood because the membrane can be commercial or non-commercial, both polymeric and hybrid organic-inorganic in nature, with regard to the electrodes, they can be of any nature and prepared by any processing method, where the components must have the desired MEA size without being limited by the assembly method of the present invention and the deposition of the catalytic layer can be carried out by both the CCS method and the CCM method.
  • the catalytic layer is deposited on the membrane (CCM) it is included in the plasticizing sheath and after plasticizing the electrodes are faced with a gas diffusion layer (GDL) to subsequently press everything.
  • GDL gas diffusion layer
  • the catalytic layer is deposited on both sides of the membrane, allowing a wide range of processing methods, with spraying being preferable, where the CCM unit would be placed inside the plasticizing sleeve (c ), to later cover the components with onion paper (d) and proceed to laminate (e).
  • This processing method allows up to 50% inorganic content to be incorporated into the membrane.
  • the membrane is selected from commercial ionomeric membranes (3) based on perfluorosulfonated polymers, ionomeric membranes based on hydrocarbon chain polymers, hybrid organic-inorganic membranes based on perfluorosulfonated polymers, hybrid organic-inorganic membranes based on ionomeric polymers.
  • the above membrane has a catalytic layer deposited by the CCM method using a deposition, chemical or physical method, preferably airbrushing, screen printing, decal transfer, electrodeposition, ion beam sputtering or magnetic sputtering.
  • step (e) allows the manufacture of the MEA unit as well as its handling, when until now it was impossible due to its fragility.
  • These hybrid membranes can be class I hybrids with the organic and inorganic components linked by weak ionic bonds, electrostatic or Van der Waals forces (known as composites) or type II with covalent bonds between components (hybrid materials on the nanometric scale. ).
  • the inorganic component can be Si, Zr, P, Al, Ti among others, or a combination of them in binary or ternary systems, for example, T ⁇ O 2 -P2O 5 or SiO 2 -P2O 5 -ZrO 2 , with a maximum content of 50% in the hybrid.
  • Alkoxides, chlorides, nitrates, acetates or citrates, among others, can be used as precursors.
  • the incorporation of the inorganic component into the hybrid can be carried out by any liquid deposition method, the most preferred embodiment being the sol-gel synthesis.
  • the organic component may be a monomer, polymer, block copolymer or a polymerizable alkylalkoxide.
  • aromatic monomers or polymers that are susceptible to sulfonation or any other monomer or polymer.
  • the organic component is incorporated into the hybrid by organic polymerization of its functional groups that vary depending on the nature of the monomer, polymer or alkylalkoxide used.
  • step (e) allows the MEA unit to be assembled and disassembled for the repetition of electrochemical tests. This processing method facilitates the incorporation of up to 50% of inorganic content.
  • the electrodes (4a and 4b) are selected from electrodes with a gas diffusion layer (GDL) made of paper, felt, fibers or carbon fabrics with (or without) a microporous layer (MPL). layer); the catalytic layer being deposited by a deposition method, either chemical or physical, preferably airbrushing, screen printing, electrodeposition, chemical vapor deposition, ion beam sputtering or magnetic sputtering.
  • GDL gas diffusion layer
  • MPL microporous layer
  • the catalytic layer being deposited by a deposition method, either chemical or physical, preferably airbrushing, screen printing, electrodeposition, chemical vapor deposition, ion beam sputtering or magnetic sputtering.
  • GDL gas diffusion layer
  • MPL microporous layer
  • the catalytic layer being deposited by a deposition method, either chemical or physical, preferably airbrushing, screen printing, electrodeposition, chemical vapor deposition, ion beam sputtering or magnetic sputtering.
  • the plasticizing covers (1) of step (b) are selected from bioriented polypropylene (BOPP), polycarbonates, polyurethanes or polyamides.
  • the laminating sleeve is made of bioriented polypropylene.
  • the bioriented polypropylene plasticizer cover comprises a coating of a layer of ethylene-vinyl acetate copolymer (EVA), with total thicknesses between 80 and 125 pm.
  • the onion-type protective paper selected from step (d) is a Parafilm vegetable paper, with a weight ranging between 40 and 100 g/m 2, cotton fiber content of 25% by weight and resistance to temperatures of up to 220 e C.
  • step (e) is carried out at a speed of between 20 cm/min and 40 cm/min.
  • a pressure is applied in step (e) which reduces the thickness of the sheath-membrane assembly obtained between 3 and 7% with respect to the ratio between the thickness of the sheath-membrane assembly at the entrance. and at the exit of the laminator.
  • step (h) is carried out at a temperature of between 100 e C and 160 e C, at a pressure of between 8 bar and 20 bar for at least 3 min.
  • step (h) the pressing conditions can be lowered, regardless of the nature of the membrane and the electrodes used, both temperature, pressure and time, with respect to conventional assembly. These milder experimental conditions avoid softening and fluidity processes of the membrane, as well as structural damage during assembly caused by high temperature and pressure conditions.
  • the cooling of stage (i) is carried out with the cooling cartridges of the hydraulic press for a time of at least 3 minutes maintaining a pressure of between 8 bar and 20 bar.
  • stage (i) the pressing conditions can be lowered, regardless of the nature of the membrane used, both temperature, pressure and time, with respect to conventional assembly. These milder experimental conditions avoid softening and fluidity processes of the membrane, as well as structural damage during assembly caused by high temperature and pressure conditions.
  • a membrane-electrode assembly unit that comprises a membrane comprising an ion exchange membrane (3) and a catalytic layer, and two electrodes on both sides of the membrane (4a and 4b) characterized in that
  • the membrane also comprises a plasticized cover (1) that covers it with a material selected from bio-engineered polypropylene (BOPP), polycarbonates, polyurethanes or polyamides, where the cover also has a hole at its midpoint making a window (2) with the measurement of the desired active area for the MEA to connect the electrodes and said membrane.
  • BOPP bio-engineered polypropylene
  • the plasticizing cover is made of bio-engineered polypropylene.
  • the plastic cover (1) is made of bio-engineered polypropylene and comprises a coating of an ethylene-vinyl acetate (EVA) copolymer, with total thicknesses between 80 and 125 pm.
  • EVA ethylene-vinyl acetate
  • the membranes are selected from among commercial ionomeric membranes based on perfluorosulfonated polymers, ionomeric membranes based on hydrocarbon chain polymers, organic-inorganic hybrid membranes based on perfluorosulfonated polymers, organic-inorganic hybrid membranes based on hydrocarbon chain ionomer polymers, ionomeric membranes based on block copolymers with styrene groups sulfonated and organic-inorganic hybrid membranes based on block copolymers with sulfonated styrene groups.
  • the above membranes have a catalytic layer deposited by the CCM method.
  • the commercial ionomeric membranes are based on perfluorosulfonated polymers or organic-inorganic hybrid membranes based on perfluorosulfonated polymers, which have improved stack efficiency compared to membranes assembled by the conventional hot-pressing method, which represents another advantage. additional.
  • the electrodes are selected from electrodes with a gas diffusion layer (GDL) made of paper, felt, carbon fibers or fabrics with (or without) a microporous layer (MPL), the catalytic layer deposited by any deposition method, whether chemical or physical, such as airbrushing, screen printing, electrodeposition, chemical vapor deposition, ion beam sputtering or magnetic sputtering.
  • GDL gas diffusion layer
  • MPL microporous layer
  • the size of the electrodes is 2.24 x 2.24 cm
  • the size of the active area or window of the laminate has to be slightly smaller, in this preferred example 2.15 x 2.15 cm
  • Fig. 1 Scheme showing the plastic cover with the central window of the size active area of the MEA unit to be prepared. Stage (b) of the invention procedure.
  • Fig. 3 Scheme of the different stages of the invention process: A. Side view of the laminated membrane (after stage e). B. Side view of the electrodes placed on both sides and with a surface slightly higher than that of the laminate-free window (stage g). C. Side view of the MEA once hot pressed (stage h) and after the cooling process (stage i). The scheme works for both CCS (Catalyst Coated on Substrate) and CCM (Catalyst Coated on Membrane) configurations.
  • CCS Catalyst Coated on Substrate
  • CCM Catalyst Coated on Membrane
  • Fig. 4. Scheme corresponding to step (g) described in the inventive procedure showing the top view after placing and facing the electrodes on each side of the laminated membrane.
  • the bottom view is identical to the top (not shown).
  • Example 1 Nature of the membranes used for the assembly of the MEA unit
  • Membranes of polymeric, inorganic and hybrid organic-inorganic nature are prepared.
  • Ionomeric polymer membranes based on block copolymers with sulfonated styrene groups are prepared from a triblock copolymer of styrene-ethylene-butylene-styrene (SEBS) with 32% by weight of styrene units which is purchased from Repsol. with the trade name Calprene CH-6120.
  • SEBS polymeric membranes are prepared by tape collage from chloroform solutions using the Dr Blade technique (BYK Instruments). The heterogeneous sulfonation reaction of SEBS (s-SEBS) is performed by immersing the polymeric membranes in a 0.3 M solution of trimethylsilyl chlorosulfonate in dichloroethane (DCE) for 2 hours.
  • DCE dichloroethane
  • Inorganic sol-gel solutions precursors of inorganic membranes are prepared using trimethyl phosphate (PO(OCH 3 )3, TMP), zirconium tetrapropoxide (Zr(OC 3 H 7 )4, TPZr) from Aldrich, orthosilicate tetraethyl (Si(OC 2 H 5 )4, TEOS) from Merck and acetylacetone (C 5 H 8 O 2 , acac) from Fluka.
  • Other chemicals used were propanol as sol-gel solution solvent (C 3 H 8 O) and acidulated water (HCl 0.1 N) as sol-gel reaction catalyst.
  • the membranes are prepared by casting in Teflon (PTFE) molds, allowing them to gel at 50 ° C for several days depending on the desired final thickness. Different compositions have been tested, the preferred composition being the one that maintains the molar ratio 40S ⁇ 0 2 -40P 2 0 5 -20Zr0 2 . A molar % proportion of P 2 O 5 of 25-60%, of ZrO 2 between 25-30% and of S ⁇ 0 2 between 50-10% can be used. (4) Organic-inorganic hybrid membranes based on s-SEBS and modified with inorganic sol-gel solutions of the SiO 2 -P2O 5 -ZrO 2 ternary oxide system. The membranes are prepared by the infiltration process.
  • PTFE Teflon
  • the s-SEBS membranes are pre-swollen in 1 N H 2 SO 4 at 80 °C for 2 h and then immersed in the 40S ⁇ 0 2 -40P 2 0 5 -20Zr0 2 solution at 80 °C for different times.
  • the preferable time is 10 minutes of infiltration.
  • the membranes are cleaned with ethanol and dried at 50 °C for 1 h and 120 °C for 2 h to ensure the formation of the gels.
  • the hybrid membranes are cleaned with ethanol at 80 °C for 2 h and dried at 80 °C for 1 h.
  • the dry infiltrated samples show an increase in area between 42% and 1 17%, and thicknesses of around 45-55 pm depending on the infiltration time.
  • All membranes are cut to a size slightly larger than the active area of the electrode to be used in the MEA. For example, if the active area is 5 cm 2 , the electrodes will be 2.24 x 2.24 cm 2 and the minimum membrane dimensions will be 3 x 3 cm 2 .
  • Polymehcas and hybrid membranes are homogeneous, transparent without cracks or defects.
  • Example 2 Obtaining the MEA unit in CCS (Catalyst Coated on Substrate) conformation
  • Membrane-electrode assemblies are prepared using ionomeric membranes of any nature (both pure polymeric and organic-inorganic hybrids) and electrodes in the CCS configuration:
  • the electrodes (4a and 4b) in this example are composed of a commercial GDL gas diffusion layer (Sigracet BC39 from SGL) and a catalytic layer spray deposited on the GDL.
  • the catalytic layer contains between 0.9-1.0 mg Pt/cm 2 and symmetrical electrodes have been used on the anode and cathode.
  • the assembly is carried out by preparing the plastic cover (1) (biohented polypropylene (BOPP) with a layer of ethylene-vinyl acetate copolymer (EVA)), making a central window (2) the size of the active area that goes to have the MEA unit ( Figure 1). 3.
  • the membrane (3) is placed inside the laminating sleeve (1) as indicated in Figure 2. It is necessary to center it well with respect to the window of the sleeve, avoiding wrinkles so that the laminating is adequate and does not produce failures in the process.
  • the cover-membrane assembly is covered with onion-type protective paper or similar so that it absorbs the pressure of the laminate, also avoiding problems of obstruction and jamming in the laminator.
  • Figure 3.B shows how the electrodes (4a and 4b) are placed on both sides of the plasticized membrane, facing them perfectly to the active area window and taking into account that each electrode always has to be slightly larger. that the window (2) of the plasticized membrane (1), that is, each electrode (4) must always slightly overlap the window (2) of the plasticized membrane, thus reducing the active area of the MEA between 3 and 8%. regarding the assembly process without lamination stage.
  • Figure 3.C shows the side view of the final MEA, after the hot pressing and cooling processes.
  • Figure 4 shows a top-down view of the final MEA. Pressing is carried out at a temperature of 100 e C at a pressure of 15 bar for 3 min in a Collin P200 hydraulic press. The cooling process is carried out using the cooling cartridges of the Collin P200 hydraulic press at a pressure of 15 bar for 3 minutes.
  • Example 3 Improvements in stack efficiency (l-V curves and power density curves) in MEA units assembled with the procedure described in this invention.
  • the maximum current density increases from 2700 mA/cm 2 to 2900 mA/cm 2 in the laminated MEAs, as seen in Figure 5.
  • the maximum power density also improves slightly, going from 922 mW/cm 2 to 923 mW/cm 2 .
  • Figure 6 compares the performance of the pure s-SEBS polymeric membrane with the organic-inorganic hybrid membrane sSEBS-(40S ⁇ 0 2 -40P 2 0 5 -20Zr0 2 ) with both assembly procedures: traditional pressing procedure in hot (Figure 6.A) and procedure of the present invention ( Figure 6.B).
  • the maximum power density obtained is 300 mW/cm 2 in the conventional MEA, however, in the laminated MEA using the procedure described in the present invention a maximum power density of 400 is obtained. mW/cm 2 (corresponding to a 33% improvement).
  • Example 4 Post-mortem evaluation of the MEA unit after the electrochemical test in the cell.

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Abstract

The present invention relates to a method for obtaining a membrane electrode assembly (MEA) unit for electrochemical devices such as fuel cells, ion exchange electrolysers, redox flow batteries and other energy generation and storage systems, which enables assembly when the membrane used is not of a purely polymer nature (non-commercial) and improves the assembly when it is. This new method comprises a step prior to pressing that facilitates the assembly between the components and improves the interfaces, facilitating its manipulation, improving its efficiency in the cell and its post-mortem analysis. The invention may fall within the area of material science and energy, and it is of interest for industries that manufacture electrochemical components, as well as small electronic devices or biomaterials.

Description

DESCRIPCIÓN DESCRIPTION
Procedimiento de obtención de una unidad de ensamblaje membrana-electrodos (MEA) en dispositivos electroquímicos. Procedure for obtaining a membrane-electrode assembly unit (MEA) in electrochemical devices.
La presente invención se refiere a un procedimiento de obtención de una unidad de ensamblaje membrana-electrodos (MEA, del inglés, Membrane Electrode Assembly) para dispositivos electroquímicos como son pilas de combustible, electrolizadores de intercambio iónico, baterías de flujo redox y otros sistemas de generación o almacenamiento de energía, que permite el ensamblaje cuando la membrana empleada no es de naturaleza puramente polimérica (no comercial) y mejora el ensamblaje cuando lo es. Este nuevo procedimiento comprende una etapa previa al prensado que facilita el ensamblaje entre los componentes y mejora las interfases, facilitando su manipulación, mejorando su eficiencia en la pila y su análisis post-mortem. La invención se puede encuadrar en el área de la ciencia de materiales y la energía, y es de interés para industrias que fabrican componentes electroquímicos, así como pequeños dispositivos electrónicos o biomateñales. The present invention refers to a procedure for obtaining a membrane-electrode assembly unit (MEA, Membrane Electrode Assembly) for electrochemical devices such as fuel cells, ion exchange electrolyzers, redox flow batteries and other storage systems. generation or storage of energy, which allows assembly when the membrane used is not purely polymeric in nature (non-commercial) and improves assembly when it is. This new procedure includes a pre-pressing stage that facilitates the assembly between the components and improves the interfaces, facilitating their handling, improving their efficiency in the stack and their post-mortem analysis. The invention can be framed in the area of materials science and energy, and is of interest to industries that manufacture electrochemical components, as well as small electronic or biomaterial devices.
ANTECEDENTES DE LA INVENCIÓN BACKGROUND OF THE INVENTION
La optimización de la etapa de procesamiento de la unidad ensamblaje membrana- electrodos (MEA) se hace necesaria sobre todo cuando se usan componentes no comerciales, nuevas capas de difusión de gases GDL (del inglés, Gas Difussion Layer), nuevas capas catalíticas o nuevas membranas. Sin embargo, el factor más determinante en este ensamblaje es la naturaleza de la membrana que se utilice en la unidad MEA. The optimization of the processing stage of the membrane-electrode assembly unit (MEA) becomes necessary especially when non-commercial components, new gas diffusion layers GDL (Gas Difussion Layer), new catalytic layers or new ones are used. membranes. However, the most determining factor in this assembly is the nature of the membrane used in the MEA unit.
En el caso concreto de las pilas de combustible de membrana de intercambio protónico (PEMFC), la membrana intercambiadora de protones actúa como electrolito transportando los protones generados en el ánodo hasta el cátodo y también como separador entre ambos electrodos. En el caso de las pilas de combustible de intercambio aniónico (AEMFC) la membrana es conductora de aniones hidroxilo. Por tanto, los requisitos que debe tener la membrana en estos dispositivos son: poseer una elevada conductividad iónica, ser aislante electrónico e impermeable tanto al combustible como al oxígeno. Asimismo, debe ser resistente química y mecánicamente en las condiciones de funcionamiento de la pila y, por último, se ha de poder obtener a bajo coste en forma de películas de bajo espesor. La mayoría de las PEMFC comerciales emplean el electrolito polimérico Nation®, desarrollado por DuPont a finales de los años sesenta, cuya estructura química consiste en una cadena poliméñca principal de politetrafluoretileno de naturaleza hidrofóbica responsable de su estabilidad mecánica y cadenas laterales finalizadas con grupos sultánicos que poseen naturaleza hidrofílica y que son las responsables del transporte iónico. En condiciones adecuadas de hidratación estos grupos sultánicos se disocian dotando al polímero de conductividad iónica. Nation® ha sido y es un material extensamente estudiado y, en principio, con las propiedades eléctricas, químicas y mecánicas necesarias para funcionar correctamente como electrolito en PEMFC. Sin embargo, la experiencia ha contribuido a determinar las desventajas que presenta su utilización y que son, en primer lugar, su elevado precio; en segundo lugar, el hecho de que su conductividad iónica disminuye significativamente con la temperatura debido a problemas de deshidratación y, por último, su elevada permeabilidad a metanol que en el caso de las pilas de metanol directo (DMFC) supone un serio e importante problema. Por todo ello han surgido diferentes líneas de investigación durante las últimas décadas que pretenden mejorar las características de Nation® o bien su sustitución por nuevos materiales con mejores prestaciones, entre otras están las membranas de intercambio protónico basadas en polímeros con grupos estireno sulfonados que mejoren la estabilidad dimensional y oxidativa del propio poliestireno sulfonado a elevados grados de humedad, por ejemplo, el estireno-etileno-butileno-estireno sulfonado (sSEBS), Sin embargo, las membranas sSEBS con altos valores de conductividad absorben mucha agua y experimentan al mismo tiempo una significativa pérdida de estabilidad dimensional que compromete su tiempo de vida. In the specific case of proton exchange membrane fuel cells (PEMFC), the proton exchange membrane acts as an electrolyte, transporting the protons generated in the anode to the cathode and also as a separator between both electrodes. In the case of anion exchange fuel cells (AEMFC) the membrane is a conductor of hydroxyl anions. Therefore, the requirements that the membrane must have in these devices are: to have a high ionic conductivity, to be electronic insulator and impermeable to both fuel and oxygen. Likewise, it must be chemically and mechanically resistant under the operating conditions of the cell and, finally, it must be obtainable at low cost in the form of thin films. Most commercial PEMFCs use the Nation® polymer electrolyte, developed by DuPont in the late sixties, whose chemical structure consists of a main polymer chain of polytetrafluoroethylene of a hydrophobic nature responsible for its mechanical stability and side chains terminated with sultanic groups that They have a hydrophilic nature and are responsible for ionic transport. Under adequate hydration conditions, these sultanic groups dissociate, giving the polymer ionic conductivity. Nation® has been and is an extensively studied material and, in principle, has the necessary electrical, chemical and mechanical properties to function correctly as an electrolyte in PEMFC. However, experience has helped determine the disadvantages of its use, which are, first of all, its high price; secondly, the fact that its ionic conductivity decreases significantly with temperature due to dehydration problems and, finally, its high permeability to methanol, which in the case of direct methanol cells (DMFC) represents a serious and important problem. . For all these reasons, different lines of research have emerged in recent decades that aim to improve the characteristics of Nation® or replace it with new materials with better performance, among others are proton exchange membranes based on polymers with sulfonated styrene groups that improve the dimensional and oxidative stability of sulfonated polystyrene itself at high levels of humidity, for example, sulfonated styrene-ethylene-butylene-styrene (sSEBS). However, sSEBS membranes with high conductivity values absorb a lot of water and at the same time experience a significant loss of dimensional stability that compromises its lifespan.
Otras membranas con grupos estireno son los polímeros de injerto basados en una cadena principal hidrofóbica y estable a la que se injertan cadenas de poliestireno sulfonado, y, además, por otro lado, están las membranas basadas en polímeros con grupos aromáticos en la cadena principal como son las polisulfonas y las poliéter-éter- cetonas; otras membranas están basadas en polifosfacenos sulfonados, poliimidas sulfonadas, especialmente las naftalénicas, así como las membranas de polibencimidazol dopado con ácido fosfórico. Sin embargo, todas ellas acarrean diferentes limitaciones y problemas: presentan conductividades inferiores a Nation®, excesivo hinchamiento y pérdida de estabilidad mecánica, limitadas propiedades mecánicas debidas a su baja temperatura de transición vitrea que mejoran a costa de funcionar en atmósferas hidratadas, inestabilidad dimensional en estado hidratado que conduce a escisiones de cadena y baja durabilidad, además de baja solubilidad que dificulta la preparación de la membrana o los problemas de difusión del ácido fosfórico hacia fuera de la membrana tras largos tiempos de funcionamiento que provocan una brusca caída de la conductividad, respectivamente. Other membranes with styrene groups are graft polymers based on a hydrophobic and stable main chain to which sulfonated polystyrene chains are grafted, and, on the other hand, there are membranes based on polymers with aromatic groups in the main chain such as They are polysulfones and polyether ether ketones; Other membranes are based on sulfonated polyphosphazenes, sulfonated polyimides, especially naphthalene ones, as well as polybenzimidazole membranes doped with phosphoric acid. However, all of them carry different limitations and problems: they have lower conductivities than Nation®, excessive swelling and loss of mechanical stability, limited mechanical properties due to their low glass transition temperature that improve at the expense of functioning in hydrated atmospheres, dimensional instability in hydrated state It leads to chain scissions and low durability, in addition to low solubility that makes membrane preparation difficult or problems with the diffusion of phosphoric acid out of the membrane after long operating times that cause a sharp drop in conductivity, respectively.
Por último, otra posibilidad es la formación de redes ionoméricas flexibles a partir de mezclas de polímeros con carácter ácido como son las polisulfonas sulfonadas y con carácter básico como el polibencimidazol. Estas redes contienen uniones iónicas formadas a partir de una transferencia protónica desde el grupo ácido al grupo básico que cuando están secas son menos frágiles que sus componentes por separado, probablemente debido a la flexibilidad de las uniones iónicas [M. Walter, K. -M. Baumgartner, M. Kaiser, J. Kerres, A. Ullrich, E. R uchle, Proton-Conducting Polymers with Reduced Methanol Permeation, J. AppL Polym. Sci. 74 (1999) 67], Finally, another possibility is the formation of flexible ionomeric networks from mixtures of polymers with an acidic character such as sulfonated polysulfones and with a basic character such as polybenzimidazole. These networks contain ionic bonds formed from a proton transfer from the acidic group to the basic group that when dry are less fragile than their separate components, probably due to the flexibility of the ionic bonds [M. Walter, K.-M. Baumgartner, M. Kaiser, J. Kerres, A. Ullrich, E. R uchle, Proton-Conducting Polymers with Reduced Methanol Permeation, J. AppL Polym. Sci. 74 (1999) 67],
Para funcionar correctamente como electrolitos en PEMFC y DMFC, tanto las membranas perfluorosulfonadas tipo Nation® como los nuevos desarrollos descritos (salvo el caso particular de las membranas de polibencimidazol dopado con ácido fosfórico) necesitan la absorción de gran cantidad de agua que en muchos casos conlleva una pérdida de estabilidad dimensional. Por otra parte, al aumentar la temperatura de trabajo por encima de 80°C se producen pérdidas muy importantes de conductividad protónica debido a problemas de deshidratación. El desarrollo de membranas híbridas orgánico-inorgánicas se muestran como la aproximación más adecuada para solventar estos problemas ya que combinan las propiedades de conformado en láminas delgadas y la conductividad protónica a baja temperatura del componente orgánico, con la estabilidad térmica y química, y la posibilidad de obtener conductividad protónica a alta temperatura que aporta el componente inorgánico, además de una disminución del crossover de metanol [D. Dhanapal, M. Xiao, S. Wang Y. Meng, A Review on Sulfonated Polymer Composite/Organic-lnorganic Hybrid Membranes to Address Methanol Barrier Issue for Methanol Fuel Cells, Nanomaterials 9(5) (2019) 668], To function correctly as electrolytes in PEMFC and DMFC, both Nation®-type perfluorosulfonated membranes and the new developments described (except for the particular case of polybenzimidazole membranes doped with phosphoric acid) require the absorption of a large amount of water, which in many cases entails a loss of dimensional stability. On the other hand, increasing the working temperature above 80°C produces very significant losses of proton conductivity due to dehydration problems. The development of hybrid organic-inorganic membranes appears to be the most appropriate approach to solve these problems since they combine the forming properties in thin sheets and the proton conductivity at low temperature of the organic component, with the thermal and chemical stability, and the possibility to obtain proton conductivity at high temperature provided by the inorganic component, in addition to a decrease in the methanol crossover [D. Dhanapal, M. Xiao, S. Wang Y. Meng, A Review on Sulfonated Polymer Composite/Organic-lnorganic Hybrid Membranes to Address Methanol Barrier Issue for Methanol Fuel Cells, Nanomaterials 9(5) (2019) 668],
Las membranas híbridas se pueden clasificar en dos grupos principales en función de la naturaleza y la fortaleza de la interacción entre ambos componentes. Las de clase I (que consisten en una matriz ionomérica en la que se dispersan partículas inorgánicas generalmente de tamaño nanométrico) en las que se establecen enlaces débiles, tipo enlaces de hidrógeno, van der Waals o fuerzas electrostáticas y las de clase II (donde la interacción entre los componentes es a nivel molecular por lo que ambos deben incluir en su estructura grupos funcionales capaces de reaccionar entre sí para formar enlaces químicos, habitualmente sintetizadas mediante sol-gel) cuyos enlaces son covalentes o iónico-covalentes. A veces la frontera entre ambas clases es difusa y puede haber sistemas con características de ambos grupos. Hybrid membranes can be classified into two main groups based on the nature and strength of the interaction between both components. Those of class I (which consist of an ionomeric matrix in which inorganic particles, generally of nanometric size, are dispersed) in which weak bonds are established, type hydrogen bonds, van der Waals or electrostatic forces and class II forces (where the interaction between the components is at a molecular level so both must include in their structure functional groups capable of reacting with each other to form chemical bonds, usually synthesized by sol-gel) whose bonds are covalent or ionic-covalent. Sometimes the border between both classes is blurred and there may be systems with characteristics of both groups.
La unidad MEA es el componente central de una pila de combustible (o electrolizador) de membrana de intercambio de iones. Para mejorar la eficiencia del procesamiento y la fabricación de dicho ensamblaje se han diseñado diferentes estrategias como la mejora de la fragilidad de la capa de difusión del gas a través de la adición de polímeros como el Teflon® o el uso de telas en vez de papel de carbón; también a través de nuevos procesamientos como el roll to roll u otros procesamientos industriales comúnmente usados en la industria de los materiales polímeros. También se ha desarrollado mucha investigación en la mejora de la tinta catalítica que se deposita sobre la capa de difusión del gas, tanto en la propia síntesis de la tinta como en el método empleado para su deposición. Por otro lado, se han descrito diversos parámetros de temperatura y presión para la etapa del ensamblaje de los componentes por prensado en caliente. The MEA unit is the central component of an ion exchange membrane fuel cell (or electrolyzer). To improve the efficiency of processing and manufacturing of said assembly, different strategies have been designed, such as improving the fragility of the gas diffusion layer through the addition of polymers such as Teflon® or the use of fabrics instead of paper. coal; also through new processing such as roll to roll or other industrial processing commonly used in the polymer materials industry. Much research has also been carried out to improve the catalytic ink that is deposited on the gas diffusion layer, both in the synthesis of the ink itself and in the method used for its deposition. On the other hand, various temperature and pressure parameters have been described for the component assembly stage by hot pressing.
El factor limitante en la mayoría de los ensamblajes membrana-electrodos por prensado en caliente es la facilidad con la que se pueden crear tensiones, sobre todo en los bordes del área activa y más aún en los puntos por los que se alimentan los gases, facilitando la formación de microgrietas que conllevan un menor rendimiento de la pila y pueden incluso acabar cortocircuitando el sistema. The limiting factor in most hot-pressed membrane-electrode assemblies is the ease with which tensions can be created, especially at the edges of the active area and even more so at the points through which the gases are fed, facilitating the formation of microcracks that lead to lower battery performance and can even end up short-circuiting the system.
Los métodos de preparación de unidades MEA se agrupan en dos técnicas [J. Zhao; S. Shahgaldi; A. Ozdenlbrahim; E. Alaefour; X. Li; F. Hamdullahpu, Effect of catalyst deposition on electrode structure, mass transport andperformance of polymer electrolyte membrane fuel cells, Applied Energy 255 (2019) 113802], dependiendo del sustrato sobre el que se deposite la capa catalítica. 1 ) Cuando la capa catalítica se deposita sobre la capa difusora de gases GDL (del inglés, Gas Difussion Layer) el método se denomina CCS (del inglés, Catalyst Coated on Substrate) o también método GDE (del inglés, Gas Difussion Electrode) [E. López-Fernández; C. Gómez Sacedón; J. Gil- Rostra; F. Yubero; A. R. González-Elipe; A. de Lucas-Consuegra, Recent Advances in Alkaline Exchange Membrane Water Electrolysis and Electrode Manufacturing, Molecules 26 (2021 ) 6326]; y 2) cuando la capa catalítica se deposita directamente sobre la membrana, denominándose método CCM (del inglés, Catalyst Coated on Membrane) [JP2006260909A, 2006-09-28]. En el método CCS la técnica más comúnmente empleada para depositar la capa catalítica es la aerografía (serigrafía, pintado, colaje...), con diferentes modificaciones. Para la técnica CCM, muy usada en los últimos años, se utiliza también la aerografía (serigrafía, pintado, colaje, etc.) directamente sobre la membrana, así como el llamado método de calcomanía (en inglés, decal transfer method). En ambas técnicas se prepara un “sandwich” entre los electrodos y la membrana; en CCS entre los electrodos ya preparados se coloca el electrolito (membrana) correspondiente y en el método CCM se utiliza una GDL puesto que las capas catalíticas ya se han depositado a ambos lados de la membrana. A continuación, se prensan en caliente, desde temperatura ambiente hasta temperaturas de 200eC [K. Talukdar; S. Delgado; T. Lagarteira; P. Gazdzicki; A. K. Friedrich, Minimizing mass-transport loss in proton exchange membrane fuel cell by freeze-drying of cathode catalyst layers, Journal of Power Sources 427 (2019)] utilizando una prensa hidráulica. La MEA se coloca en la celda de medida normalmente entre dos sellos para evitar las fugas de gas y los cortocircuitos entre las placas bipolares y/o terminales. The methods of preparing MEA units are grouped into two techniques [J. Zhao; S. Shahgaldi; A. Ozdenlbrahim; E. Alaefour; X. Li; F. Hamdullahpu, Effect of catalyst deposition on electrode structure, mass transport and performance of polymer electrolyte membrane fuel cells, Applied Energy 255 (2019) 113802], depending on the substrate on which the catalytic layer is deposited. 1) When the catalytic layer is deposited on the gas diffusion layer GDL (Gas Difussion Layer), the method is called CCS (Catalyst Coated on Substrate) or also the GDE method (Gas Difussion Electrode) [ AND. López-Fernández; C. Gómez Sacedón; J. Gil-Rostra; F. Yubero; AR González-Elipe; A. de Lucas-Consuegra, Recent Advances in Alkaline Exchange Membrane Water Electrolysis and Electrode Manufacturing, Molecules 26 (2021) 6326]; and 2) when the catalytic layer is deposited directly on the membrane, called the CCM method (Catalyst Coated on Membrane) [JP2006260909A, 2006-09-28]. In the CCS method, the most commonly used technique to deposit the catalytic layer is airbrushing (screen printing, painting, collage...), with different modifications. For the CCM technique, widely used in recent years, airbrushing (screen printing, painting, collage, etc.) is also used directly on the membrane, as well as the so-called decal transfer method. In both techniques, a “sandwich” is prepared between the electrodes and the membrane; In CCS, the corresponding electrolyte (membrane) is placed between the already prepared electrodes and in the CCM method a GDL is used since the catalytic layers have already been deposited on both sides of the membrane. They are then hot pressed, from room temperature to temperatures of 200 e C [K. Talukdar; S. Delgado; T. Lagarteira; P. Gazdzicki; AK Friedrich, Minimizing mass-transport loss in proton exchange membrane fuel cell by freeze-drying of cathode catalyst layers, Journal of Power Sources 427 (2019)] using a hydraulic press. The MEA is placed in the measurement cell normally between two seals to prevent gas leaks and short circuits between the bipolar and/or terminal plates.
No obstante, hasta el momento no se han reportado ensamblajes de unidades MEA que mejoren las propiedades mecánicas, que mejoren la difusión de los gases externos o mejoren las interfases electrodo-electrolito. Tampoco se han reportado hasta el momento ensamblajes de unidad MEA que permitan utilizar membranas puramente inorgánicas o híbridas orgánico-inorgánicas con alto contenido de componente no poliméhco. However, so far no MEA unit assemblies have been reported that improve the mechanical properties, that improve the diffusion of external gases or that improve the electrode-electrolyte interfaces. Nor have any MEA unit assemblies been reported so far that allow the use of purely inorganic or hybrid organic-inorganic membranes with a high content of non-polymeric component.
DESCRIPCIÓN DE LA INVENCIÓN DESCRIPTION OF THE INVENTION
La presente invención se refiere a un procedimiento de obtención de una pieza clave en las pilas de combustible y los electrolizadores de baja temperatura como es el ensamblaje membrana-electrodos, la unidad MEA. El nuevo procedimiento supone una especial ventaja cuando la membrana es de naturaleza inorgánica o híbrida orgánico- inorgánica con alto contenido de componente no poliméhco las cuales muestran mayor fragilidad lo que dificulta su ensamblaje y manipulación. The present invention refers to a procedure for obtaining a key part in fuel cells and low temperature electrolyzers such as the membrane-electrode assembly, the MEA unit. The new procedure is a special advantage when the membrane is of an inorganic or organic-inorganic hybrid nature with a high content of non-polymehco component, which show greater fragility, which makes its assembly and handling difficult.
El procedimiento descrito en la presente invención tiene especial interés para el usuario final, para industrias que fabrican pilas de combustible y/o electrolizadores, dispositivos de almacenamiento de energía e industrias del transporte (tanto doméstico como aeronáutico, naval, ferroviario) así como pequeños dispositivos electrónicos. También puede ser útil en la fabricación de baterías de flujo redox y en sus diferentes aplicaciones. Por otro lado, puede tener interés en empresas que fabrican capas difusoras de gases o catalizadores. The procedure described in the present invention is of special interest for the end user, for industries that manufacture fuel cells and/or electrolyzers, energy storage devices and transportation industries (both domestic and aeronautical, naval, railway) as well as small electronic devices. It can also be useful in the manufacture of redox flow batteries and in their different applications. On the other hand, you may have interest in companies that manufacture gas diffusion layers or catalysts.
En un primer aspecto, la presente invención se refiere a un procedimiento de obtención de una unidad MEA (ensamblaje membrana-electrodos) a través de los procesos de laminado y prensado (a partir de aquí “procedimiento de la invención”) que comprende las siguientes etapas: a) precalentar una laminadora que tenga un sistema de liberación de rodillos, durante al menos 4 minutos a una temperatura de entre 75 eC y 125 eC; b) agujerear una funda de plastificado (1 ) en su punto medio haciendo una ventana (2) con la medida del área activa deseada para la unidad MEA; c) colocar una membrana (3) en el interior de la funda de plastificado de la etapa (b), constituyendo el conjunto funda-membrana; d) cubrir con papel protector tipo cebolla el conjunto funda-membrana obtenido en (c); e) plastificar con la laminadora precalentada del paso (a) el conjunto funda- membrana obtenido en (d) a una temperatura entre 75 y 125 eC; f) retirar manualmente el papel protector tipo cebolla del producto laminado obtenido en (e), quedando la membrana laminada; g) colocar dos electrodos (4a y 4b) en forma de sándwich sobre la membrana laminada obtenida en la etapa (f) enfrentándolos al hueco de la ventana libre de funda de plastificado creada en (b), donde el tamaño del perímetro de dichos electrodos es superior en perímetro al de la ventana de la funda de plastificado; h) prensar el laminado obtenido en (g) a una temperatura de entre 100 eC y 160 eC, a una presión de entre 8 bar y 20 bar durante al menos 3 min. i) enfriar hasta una temperatura de entre 20 eC y 30eC, el ensamblaje obtenido en (h) aplicando una presión entre 8 bar y 20 bar durante al menos 3 minutos. In a first aspect, the present invention refers to a procedure for obtaining an MEA unit (membrane-electrode assembly) through laminating and pressing processes (hereinafter "method of the invention") that comprises the following steps: a) preheat a laminator that has a roller release system, for at least 4 minutes at a temperature between 75 e C and 125 e C; b) hole a plastic cover (1) at its midpoint making a window (2) with the measurement of the desired active area for the MEA unit; c) placing a membrane (3) inside the plastic cover of step (b), constituting the cover-membrane assembly; d) cover the sheath-membrane assembly obtained in (c) with onion-type protective paper; e) laminate with the preheated laminator from step (a) the cover-membrane assembly obtained in (d) at a temperature between 75 and 125 e C; f) manually remove the onion-type protective paper from the laminated product obtained in (e), leaving the laminated membrane; g) place two electrodes (4a and 4b) in a sandwich shape on the laminated membrane obtained in step (f) facing them to the gap of the window free of plastic sheath created in (b), where the size of the perimeter of said electrodes It is larger in perimeter than the window in the plastic case; h) press the laminate obtained in (g) at a temperature of between 100 e C and 160 e C, at a pressure of between 8 bar and 20 bar for at least 3 min. i) cool to a temperature between 20 e C and 30 e C, the assembly obtained in (h) by applying a pressure between 8 bar and 20 bar for at least 3 minutes.
La laminadora debe tener un sistema de liberación de rodillos (dos o cuatro) para evitar posibles atascos que puedan dañar el conjunto funda-membrana. Además, el uso de papel tipo cebolla o similar tiene el objeto de cubrir el conjunto funda-membrana para facilitar el paso a través de los rodillos de la plastificadora sin que se produzcan atascos, evitándose así daños durante el plastificado. Una vez dispuestos de manera adecuada el conjunto funda-membrana que se pretende obtener, el plastificado debe sellar la membrana respetando su dimensionalidad respecto a la funda de plastificado usada. Asimismo, la temperatura del proceso puede oscilar en función del espesor del conjunto, donde para espesores de 80 pm la temperatura es de 75 eC y para espesores mayores puede alcanzar hasta 125 eC. El electrodo siempre debe superponerse ligeramente a la ventana del laminado, reduciéndose así el área activa de la MEA entre un 3 y 8 %, respecto al proceso de ensamblaje sin etapa de laminación. Por ejemplo, si el tamaño de los electrodos es de 2.24 x 2.24 cm2, el tamaño del área activa (ventana del laminado) tiene que ser ligeramente inferior, en este ejemplo preferido 2.15 x 2.15 cm2, reduciéndose el área activa en 7.8 %. The laminator must have a roller release system (two or four) to avoid possible jams that could damage the cover-membrane assembly. Furthermore, the use of onion paper or similar is intended to cover the sheath-membrane assembly to facilitate passage through the laminator rollers without causing jams, thus avoiding damage during laminating. Once the sheath-membrane assembly that is intended to be obtained has been properly arranged, the laminating must seal the membrane respecting its dimensionality with respect to the laminating sheath used. Likewise, the temperature of the process can oscillate depending on the thickness of the assembly, where for thicknesses of 80 pm the temperature is 75 e C and for greater thicknesses it can reach up to 125 e C. The electrode must always slightly overlap the laminate window. , thus reducing the active area of the MEA between 3 and 8%, compared to the assembly process without a lamination stage. For example, if the size of the electrodes is 2.24 x 2.24 cm 2 , the size of the active area (laminate window) has to be slightly smaller, in this preferred example 2.15 x 2.15 cm 2 , reducing the active area by 7.8% .
El procedimiento de la presente invención supone numerosas ventajas como son que la unidad MEA que se obtiene se encuentra bien ensamblada, con todos los componentes unidos y tras el ensayo en la pila su dimensionalidad no cambia, permitiéndose así realizar ensayos post-mortem que pueden ayudar a entender el funcionamiento de la unidad MEA o repetir la caracterización electroquímica con posterioridad si fuera necesario. Otra ventaja que supone el procedimiento de la invención sería que se pueden rebajar las condiciones experimentales de prensado en la etapa (h) independientemente de la naturaleza de la membrana empleada, tanto temperatura como presión y tiempo, evitándose procesos de reblandecimiento y fluidez de la membrana, así como daños estructurales. Otra ventaja adicional es que tanto con membranas 100% poliméñcas (ya sean comerciales tipo Nation® u otras composiciones no comerciales) como con membranas híbridas orgánico-inorgánicas la etapa (e) facilita el contacto entre las interfases membrana-electrodo, mejorándose la eficiencia en la pila respecto a membranas ensambladas por el método convencional por prensado en caliente. En el caso de membranas híbridas orgánico-inorgánicas con alto contenido de componente inorgánico que aporta fragilidad, la etapa (e) permite la fabricación de la unidad MEA, su manipulación, así como sucesivos procesos de montaje y desmontaje para la repetición de ensayos electroquímicos. Este método de procesamiento facilita la incorporación a la membrana híbrida de hasta un 50% de contenido en inorgánicos. El procedimiento de la invención aumenta el rendimiento electroquímico en la pila, independientemente de la naturaleza de la membrana y de los electrodos usados en el ensamblaje, gracias a la mejora de las interfases electrodo-electrolito y a la mejor difusión de los gases en los extremos del área activa de la unidad MEA. En la presente invención se entiende por “papel cebolla” a cualquier papel vegetal que al igual que el papel de seda sea excepcionalmente ligero y delgado; translúcido y flexible con textura satinada. Aunque delgado, es extremadamente resistente debido a su formación uniforme de fibras y al contenido de fibra de algodón del 25%, lo que permite grandes propiedades de plegado adecuadas. The procedure of the present invention has numerous advantages such as that the MEA unit obtained is well assembled, with all the components joined together and after the test in the pile its dimensionality does not change, thus allowing post-mortem tests to be carried out that can help to understand the operation of the MEA unit or repeat the electrochemical characterization later if necessary. Another advantage of the procedure of the invention would be that the experimental pressing conditions can be lowered in step (h) regardless of the nature of the membrane used, both temperature, pressure and time, avoiding softening and fluidity processes of the membrane. , as well as structural damage. Another additional advantage is that both with 100% polymeric membranes (whether commercial Nation® type or other non-commercial compositions) and with organic-inorganic hybrid membranes, step (e) facilitates contact between the membrane-electrode interfaces, improving efficiency in the stack with respect to membranes assembled by the conventional hot pressing method. In the case of organic-inorganic hybrid membranes with a high content of inorganic component that contributes fragility, step (e) allows the manufacture of the MEA unit, its handling, as well as successive assembly and disassembly processes for the repetition of electrochemical tests. This processing method facilitates the incorporation of up to 50% inorganic content into the hybrid membrane. The process of the invention increases the electrochemical performance in the cell, regardless of the nature of the membrane and the electrodes used in the assembly, thanks to the improvement of the electrode-electrolyte interfaces and the better diffusion of the gases at the ends of the cell. active area of the MEA unit. In the present invention, “onion paper” is understood as any vegetable paper that, like tissue paper, is exceptionally light and thin; translucent and flexible with satin texture. Although thin, it is extremely strong due to its uniform fiber formation and 25% cotton fiber content, allowing for large suitable folding properties.
Se le conoce también como papel sulfurizado, papel de horno, papel mantequilla, papel de seda o papel vegetal, se trata químicamente (se le da un baño en ácido sulfúrico, de ahí el nombre) para tapar los poros de la celulosa y así hacerlo impermeable, traslucido y para que además sea resistente a las elevadas temperaturas. En el caso de este procedimiento se usa por sus principales características de antiadherencia y resistencia térmica para resistir temperaturas de hasta 220 °C aproximadamente y es seleccionado sin limitarse a papel vegetal Parafilm, con un gramaje que oscila entre 40 y 100 g/m2. It is also known as sulfurized paper, baking paper, butter paper, tissue paper or vegetable paper, it is chemically treated (it is given a bath in sulfuric acid, hence the name) to cover the pores of the cellulose and thus make it waterproof, translucent and also resistant to high temperatures. In the case of this procedure, it is used for its main characteristics of non-adhesion and thermal resistance to withstand temperatures of up to approximately 220 °C and is selected without being limited to Parafilm vegetable paper, with a weight that ranges between 40 and 100 g/m 2 .
En una realización preferida, antes de la etapa (a), se realiza una etapa previa de preparación de los componentes de la unidad MEA, la membrana (3) y los electrodos (4a y 4b), al tamaño deseado, y mediante un método CCS o un método CCM. In a preferred embodiment, before step (a), a previous stage of preparation of the components of the MEA unit, the membrane (3) and the electrodes (4a and 4b), is carried out to the desired size, and by a method CCS or a CCM method.
En la presente invención “la preparación de los componentes de la unidad MEA" se entiende porque la membrana puede ser comercial o no comercial tanto de naturaleza poliméñca como híbrida orgánico-inorgánica, en lo referente a los electrodos, éstos pueden ser de cualquier naturaleza y preparados mediante cualquier método de procesamiento, donde los componentes deben de tener el tamaño de la MEA deseada sin estar éste limitado por el método de ensamblaje de la presente invención y la deposición de la capa catalítica puede realizarse tanto mediante el método CCS como el método CCM. Cuando la capa catalítica se deposita sobre la membrana (CCM) va incluida en la funda de plastificado y después de plastificar se enfrentan los electrodos con capa de difusión de gases (GDL) para posteriormente prensar todo. En este caso, en la etapa de preparación de los componentes de la MEA, se deposita la capa catalítica sobre ambos lados de la membrana, permitiendo un amplio abanico de métodos de procesamiento, siendo preferible el pulverizado, donde se colocaría la unidad CCM en el interior de la funda de plastificado (c), para posteriormente cubrir los componentes con papel de cebolla (d) y proceder al laminado (e). Este método de procesamiento permite incorporar a la membrana hasta un 50% de contenido en inorgánicos. In the present invention "the preparation of the components of the MEA unit" is understood because the membrane can be commercial or non-commercial, both polymeric and hybrid organic-inorganic in nature, with regard to the electrodes, they can be of any nature and prepared by any processing method, where the components must have the desired MEA size without being limited by the assembly method of the present invention and the deposition of the catalytic layer can be carried out by both the CCS method and the CCM method. When the catalytic layer is deposited on the membrane (CCM) it is included in the plasticizing sheath and after plasticizing the electrodes are faced with a gas diffusion layer (GDL) to subsequently press everything. Preparation of the MEA components, the catalytic layer is deposited on both sides of the membrane, allowing a wide range of processing methods, with spraying being preferable, where the CCM unit would be placed inside the plasticizing sleeve (c ), to later cover the components with onion paper (d) and proceed to laminate (e). This processing method allows up to 50% inorganic content to be incorporated into the membrane.
En el método CCS sólo se incluye en la funda la membrana sin capa catalítica puesto que la capa catalítica se deposita directamente sobre los electrodos con capa de difusión de gases (GDL). In the CCS method, only the membrane without a catalytic layer is included in the sheath since the catalytic layer is deposited directly on the electrodes with a diffusion layer. of gases (GDL).
En otra realización preferida la membrana se selección de entre membranas (3) ionómeras comerciales basadas en polímeros perfluorosulfonados, membranas ionómeras basadas en polímeros de cadena hidrocarbonada, membranas híbridas orgánico-inorgánicas basadas en polímeros perfluorosulfonados, membranas híbridas orgánico-inorgánicas basadas en polímeros ionómeros de cadena hidrocarbonada, membranas ionómeras basadas en copolímeros de bloque con grupos estireno sulfonados y membranas híbridas orgánico-inorgánicas basadas en copolímeros de bloque con grupos estireno sulfonados. En otra realización más preferida la membrana anteriores tiene una capa catalítica depositada por el método CCM mediante un método de deposición, química o física, preferiblemente aerografiado, serigrafía, decal transfer, electrodeposición, pulverización con haz de iones o pulverización catódica magnética.. In another preferred embodiment, the membrane is selected from commercial ionomeric membranes (3) based on perfluorosulfonated polymers, ionomeric membranes based on hydrocarbon chain polymers, hybrid organic-inorganic membranes based on perfluorosulfonated polymers, hybrid organic-inorganic membranes based on ionomeric polymers. hydrocarbon chain, ionomeric membranes based on block copolymers with sulfonated styrene groups and organic-inorganic hybrid membranes based on block copolymers with sulfonated styrene groups. In another more preferred embodiment, the above membrane has a catalytic layer deposited by the CCM method using a deposition, chemical or physical method, preferably airbrushing, screen printing, decal transfer, electrodeposition, ion beam sputtering or magnetic sputtering.
Otra ventaja del procedimiento es que con las membranas híbridas orgánico- inorgánicas, aquellas que son conocidas como de alto contenido en componente inorgánico y elevada fragilidad, la etapa (e) permite la fabricación de la unidad MEA así como su manipulación, cuando hasta ahora era imposible por su fragilidad. Estas membranas híbridas pueden ser híbridas de clase I con los componentes orgánico e inorgánico enlazados por enlaces débiles tipo iónico, fuerzas electrostáticas o de Van der Waals (conocidos como composites) o de tipo II con enlace covalente entre componentes (materiales híbridos en la escala nanométrica). El componente inorgánico puede ser de Si, Zr, P, Al, Ti entre otros, o una combinación de ellos en sistemas binarios o ternarios, por ejemplo, T¡O2-P2O5 o SiO2-P2O5-ZrO2, con un contenido máximo del 50% en el híbrido. Se pueden utilizar como precursores alcóxidos, cloruros, nitratos, acetatos o citratos entre otros. La incorporación del componente inorgánico al híbrido se puede realizar por cualquier método de deposición vía líquida, siendo la realización más preferida la síntesis sol-gel. El componente orgánico puede ser un monómero, polímero, copolímero de bloque o un alquilalcóxido polimerizable. En una realización preferida los monómeros o polímeros aromáticos que sean susceptibles de sulfonar o cualquier otro monómero o polímero. El componente orgánico se incorpora al híbrido por polimerización orgánica de sus grupos funcionales que vaharan en función de la naturaleza del monómero, polímero o alquilalcóxido usado. Además, la etapa (e) permite montar y desmontar la unidad MEA para la repetición de ensayos electroquímicos. Este método de procesamiento facilita la incorporación a la membrana de hasta un 50% de contenido en inorgánicos. Another advantage of the procedure is that with organic-inorganic hybrid membranes, those that are known to have a high inorganic component content and high fragility, step (e) allows the manufacture of the MEA unit as well as its handling, when until now it was impossible due to its fragility. These hybrid membranes can be class I hybrids with the organic and inorganic components linked by weak ionic bonds, electrostatic or Van der Waals forces (known as composites) or type II with covalent bonds between components (hybrid materials on the nanometric scale. ). The inorganic component can be Si, Zr, P, Al, Ti among others, or a combination of them in binary or ternary systems, for example, T¡O 2 -P2O 5 or SiO 2 -P2O 5 -ZrO 2 , with a maximum content of 50% in the hybrid. Alkoxides, chlorides, nitrates, acetates or citrates, among others, can be used as precursors. The incorporation of the inorganic component into the hybrid can be carried out by any liquid deposition method, the most preferred embodiment being the sol-gel synthesis. The organic component may be a monomer, polymer, block copolymer or a polymerizable alkylalkoxide. In a preferred embodiment, aromatic monomers or polymers that are susceptible to sulfonation or any other monomer or polymer. The organic component is incorporated into the hybrid by organic polymerization of its functional groups that vary depending on the nature of the monomer, polymer or alkylalkoxide used. In addition, step (e) allows the MEA unit to be assembled and disassembled for the repetition of electrochemical tests. This processing method facilitates the incorporation of up to 50% of inorganic content.
En otra realización preferida los electrodos (4a y 4b) son seleccionados de entre electrodos con capa de difusión de gases (GDL) fabricada en papel, fieltro, fibras o telas de carbón con (o sin) capa microporosa (MPL, del inglés Micro Porous Layer); estando la capa catalítica depositada mediante un método de deposición ya sea química o física, preferiblemente aerografía, serigrafía, electrodeposición, deposición química en estado de vapor, pulverización con haz de iones o pulverización catódica magnética. Entre las distintas marcas comerciales están las GDL Toray, Sigracet, Freudenberg o ELAT E- Tek. In another preferred embodiment, the electrodes (4a and 4b) are selected from electrodes with a gas diffusion layer (GDL) made of paper, felt, fibers or carbon fabrics with (or without) a microporous layer (MPL). layer); the catalytic layer being deposited by a deposition method, either chemical or physical, preferably airbrushing, screen printing, electrodeposition, chemical vapor deposition, ion beam sputtering or magnetic sputtering. Among the different commercial brands are GDL Toray, Sigracet, Freudenberg or ELAT E-Tek.
En otra realización preferida del procedimiento las fundas plastificadoras (1 ) de la etapa (b) son seleccionadas de entre polipropileno biorientado (BOPP), policarbonatos, poliuretanos o poliamidas. En una realización más preferida la funda plastificadora es de polipropileno biorientado. En una realización aún más preferida la funda plastificadora de polipropileno biorientado comprende un recubrimiento de una capa de copolímero de etileno-acetato de vinilo (EVA), con espesores totales comprendidos entre 80 y 125 pm. In another preferred embodiment of the procedure, the plasticizing covers (1) of step (b) are selected from bioriented polypropylene (BOPP), polycarbonates, polyurethanes or polyamides. In a more preferred embodiment, the laminating sleeve is made of bioriented polypropylene. In an even more preferred embodiment, the bioriented polypropylene plasticizer cover comprises a coating of a layer of ethylene-vinyl acetate copolymer (EVA), with total thicknesses between 80 and 125 pm.
En otra realización preferida el papel protector tipo cebolla seleccionado de la etapa (d) es un papel vegetal Parafilm, con un gramaje que oscila entre 40 y 100 g/m2 contenido en fibras de algodón del 25 % en peso y resistencia a temperaturas de hasta 220 eC. In another preferred embodiment, the onion-type protective paper selected from step (d) is a Parafilm vegetable paper, with a weight ranging between 40 and 100 g/m 2, cotton fiber content of 25% by weight and resistance to temperatures of up to 220 e C.
En otra realización preferida el plastificado de la etapa (e) se realiza a una velocidad de entre 20 cm/min y 40 cm/min. In another preferred embodiment, the laminating of step (e) is carried out at a speed of between 20 cm/min and 40 cm/min.
En otra realización preferida durante el plastificado se aplica una presión en la etapa (e) la cual reduce el espesor del conjunto funda-membrana obtenido entre un 3 y 7 % con respecto a la relación entre el espesor del conjunto funda-membrana a la entrada y a la salida de la laminadora. In another preferred embodiment, during plasticizing, a pressure is applied in step (e) which reduces the thickness of the sheath-membrane assembly obtained between 3 and 7% with respect to the ratio between the thickness of the sheath-membrane assembly at the entrance. and at the exit of the laminator.
En otra realización preferida si el tamaño de los electrodos es de 2.24 x 2.24 cm2, el tamaño del área activa o ventana del laminado tiene que ser ligeramente inferior, en este ejemplo preferido 2.15 x 2.15 cm2, reduciéndose el área activa en 7.8 %. En otra realización preferida el prensado de la etapa (h) se realiza a una temperatura de entre 100 eC y 160 eC, a una presión de entre 8 bar y 20 bar durante al menos 3 min.In another preferred embodiment, if the size of the electrodes is 2.24 x 2.24 cm 2 , the size of the active area or window of the laminate has to be slightly smaller, in this preferred example 2.15 x 2.15 cm 2 , reducing the active area by 7.8%. . In another preferred embodiment, the pressing of step (h) is carried out at a temperature of between 100 e C and 160 e C, at a pressure of between 8 bar and 20 bar for at least 3 min.
Una ventaja que supone el procedimiento de la invención sería que en la etapa (h) se pueden rebajar las condiciones del prensado, independientemente de la naturaleza de la membrana y los electrodos empleados, tanto temperatura como presión y tiempo, respecto al ensamblaje convencional. Estas condiciones experimentales más suaves evitan procesos de reblandecimiento y fluidez de la membrana, así como daños estructurales durante el ensamblaje provocados por elevadas condiciones de temperatura y presión. An advantage of the method of the invention would be that in step (h) the pressing conditions can be lowered, regardless of the nature of the membrane and the electrodes used, both temperature, pressure and time, with respect to conventional assembly. These milder experimental conditions avoid softening and fluidity processes of the membrane, as well as structural damage during assembly caused by high temperature and pressure conditions.
En otra realización preferida el enfriamiento de la etapa (i) se realiza con los cartuchos de enfriamiento de la prensa hidráulica durante un tiempo de al menos 3 minutos manteniendo una presión de entre 8 bar y 20 bar. In another preferred embodiment, the cooling of stage (i) is carried out with the cooling cartridges of the hydraulic press for a time of at least 3 minutes maintaining a pressure of between 8 bar and 20 bar.
Una ventaja que supone el procedimiento de la invención sería que en la etapa (i) se pueden rebajar las condiciones del prensado, independientemente de la naturaleza de la membrana empleada, tanto temperatura como presión y tiempo, respecto al ensamblaje convencional. Estas condiciones experimentales más suaves evitan procesos de reblandecimiento y fluidez de la membrana, así como daños estructurales durante el ensamblaje provocados por elevadas condiciones de temperatura y presión. An advantage of the process of the invention would be that in stage (i) the pressing conditions can be lowered, regardless of the nature of the membrane used, both temperature, pressure and time, with respect to conventional assembly. These milder experimental conditions avoid softening and fluidity processes of the membrane, as well as structural damage during assembly caused by high temperature and pressure conditions.
Otro aspecto de la invención es una unidad de ensamblaje membrana-electrodos que comprende una membrana que comprende en una membrana de intercambio iónico (3) y una capa catalítica, y dos electrodos a ambos lados de la membrana (4a y 4b) caracterizado por que la membrana además comprende una funda plastificada (1 ) que la recubre de un material seleccionado de entre polipropileno bioñentado (BOPP), policarbonatos, poliuretanos o poliamidas, donde la funda además presenta un agujero en su punto medio haciendo una ventana (2) con la medida del área activa deseada para el MEA para conectar los electrodos y dicha membrana. Another aspect of the invention is a membrane-electrode assembly unit that comprises a membrane comprising an ion exchange membrane (3) and a catalytic layer, and two electrodes on both sides of the membrane (4a and 4b) characterized in that The membrane also comprises a plasticized cover (1) that covers it with a material selected from bio-engineered polypropylene (BOPP), polycarbonates, polyurethanes or polyamides, where the cover also has a hole at its midpoint making a window (2) with the measurement of the desired active area for the MEA to connect the electrodes and said membrane.
En otra realización preferida la funda plastificadora es de polipropileno bioñentado. En una realización aún más preferida la funda de plastificado (1 ) es de polipropileno bioñentado y comprende un recubrimiento de un copolímero de etileno-acetato de vinilo (EVA), con espesores totales comprendidos entre 80 y 125 pm. In another preferred embodiment, the plasticizing cover is made of bio-engineered polypropylene. In an even more preferred embodiment, the plastic cover (1) is made of bio-engineered polypropylene and comprises a coating of an ethylene-vinyl acetate (EVA) copolymer, with total thicknesses between 80 and 125 pm.
En una realización preferida del dispositivo las membranas son seleccionadas de entre membranas ionómeras comerciales basadas en polímeros perfluorosulfonados, membranas ionómeras basadas en polímeros de cadena hidrocarbonada, membranas híbridas orgánico-inorgánicas basadas en polímeros perfluorosulfonados, membranas híbridas orgánico-inorgánicas basadas en polímeros ionómeros de cadena hidrocarbonada, membranas ionómeras basadas en copolímeros de bloque con grupos estireno sulfonados y membranas híbridas orgánico-inorgánicas basadas en copolímeros de bloque con grupos estireno sulfonados. En otra realización más preferida las membranas anteriores tienen una capa catalítica depositada por el método CCM. En otra realización preferida las membranas ionómeras comerciales están basadas en polímeros perfluorosulfonados o membranas híbridas orgánico-inorgánicas basadas en polímeros perfluorosulfonados, las que presentan una eficiencia en la pila mejorada respecto a membranas ensambladas por el método convencional por prensado en caliente lo cual supone otra ventaja adicional. In a preferred embodiment of the device the membranes are selected from among commercial ionomeric membranes based on perfluorosulfonated polymers, ionomeric membranes based on hydrocarbon chain polymers, organic-inorganic hybrid membranes based on perfluorosulfonated polymers, organic-inorganic hybrid membranes based on hydrocarbon chain ionomer polymers, ionomeric membranes based on block copolymers with styrene groups sulfonated and organic-inorganic hybrid membranes based on block copolymers with sulfonated styrene groups. In another more preferred embodiment, the above membranes have a catalytic layer deposited by the CCM method. In another preferred embodiment, the commercial ionomeric membranes are based on perfluorosulfonated polymers or organic-inorganic hybrid membranes based on perfluorosulfonated polymers, which have improved stack efficiency compared to membranes assembled by the conventional hot-pressing method, which represents another advantage. additional.
En otra realización preferida los electrodos son seleccionados de entre electrodos con capa de difusión de gases (GDL) fabricada en papel, fieltro, fibras o telas de carbón con (o sin) capa microporosa (MPL, del inglés Micro Porous Layer), estando la capa catalítica depositada mediante cualquier método de deposición ya sea químico o físico, como puede ser aerografía, sehgrafía, electrodeposición, deposición química en estado de vapor, pulverización con haz de iones o pulverización catódica magnética. In another preferred embodiment, the electrodes are selected from electrodes with a gas diffusion layer (GDL) made of paper, felt, carbon fibers or fabrics with (or without) a microporous layer (MPL), the catalytic layer deposited by any deposition method, whether chemical or physical, such as airbrushing, screen printing, electrodeposition, chemical vapor deposition, ion beam sputtering or magnetic sputtering.
En otra realización preferida si el tamaño de los electrodos es de 2.24 x 2.24 cm, el tamaño del área activa o ventana del laminado tiene que ser ligeramente inferior, en este ejemplo preferido 2.15 x 2.15 cm In another preferred embodiment if the size of the electrodes is 2.24 x 2.24 cm, the size of the active area or window of the laminate has to be slightly smaller, in this preferred example 2.15 x 2.15 cm
A lo largo de la descripción y las reivindicaciones la palabra "comprende" y sus variantes no pretenden excluir otras características técnicas, aditivos, componentes o pasos. Para los expertos en la materia, otros objetos, ventajas y características de la invención se desprenderán en parte de la descripción y en parte de la práctica de la invención. Los siguientes ejemplos y figuras se proporcionan a modo de ilustración, y no se pretende que sean limitativos de la presente invención. Throughout the description and claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will emerge partly from the description and partly from the practice of the invention. The following examples and figures are provided by way of illustration, and are not intended to be limiting of the present invention.
BREVE DESCRIPCIÓN DE LAS FIGURAS BRIEF DESCRIPTION OF THE FIGURES
Fig. 1 . Esquema que muestra la funda de plastificado con la ventana central del tamaño de área activa de la unidad MEA que se vaya a preparar. Etapa (b) del procedimiento de la invención. Fig. 1. Scheme showing the plastic cover with the central window of the size active area of the MEA unit to be prepared. Stage (b) of the invention procedure.
Fig. 2. Esquema del conjunto funda-membrana que constituye la etapa (c) del procedimiento de invención. Fig. 2. Scheme of the sheath-membrane assembly that constitutes stage (c) of the invention procedure.
Fig. 3. Esquema de las distintas etapas del proceso de invención: A. Vista lateral de la membrana laminada (tras la etapa e). B. Vista lateral de los electrodos colocados a ambos lados y con una superficie ligeramente superior a la de la ventana libre de laminado (etapa g). C. Vista lateral de la MEA una vez prensada en caliente (etapa h) y tras el proceso de enfriamiento (etapa i). El esquema sirve para ambas configuraciones tanto CCS (Catalyst Coated on Substrate) como CCM (Catalyst Coated on Membrane). Fig. 3. Scheme of the different stages of the invention process: A. Side view of the laminated membrane (after stage e). B. Side view of the electrodes placed on both sides and with a surface slightly higher than that of the laminate-free window (stage g). C. Side view of the MEA once hot pressed (stage h) and after the cooling process (stage i). The scheme works for both CCS (Catalyst Coated on Substrate) and CCM (Catalyst Coated on Membrane) configurations.
Fig. 4. Esquema correspondiente a la etapa (g) descrita en el procedimiento de invención en la que se muestra la vista superior después de colocar y enfrentar los electrodos a cada lado de la membrana laminada. La vista inferior es idéntica a la superior (no se muestra). Fig. 4. Scheme corresponding to step (g) described in the inventive procedure showing the top view after placing and facing the electrodes on each side of the laminated membrane. The bottom view is identical to the top (not shown).
Fig. 5. Ensayo en monocelda PEMFC H2/O2 a una temperatura de 80eC, 100% de humedad relativa y presión atmosférica de una membrana Nation® N1 12 con procesamiento de MEA convencional de prensado en caliente y con procesamiento descrito en esta invención con laminado y posterior prensado en caliente. Fig. 5. PEMFC H 2 /O 2 single-cell test at a temperature of 80 e C, 100% relative humidity and atmospheric pressure of a Nation® N1 12 membrane with conventional hot-pressed MEA processing and with processing described in this invention with lamination and subsequent hot pressing.
Fig. 6. Ensayos en monocelda PEMFC H2/O2 a una temperatura de 60eC, 100% de humedad relativa y presión atmosférica de una membrana polimérica, inorgánica e híbrida orgánico-inorgánica (A) con procesamiento de MEA convencional de prensado en caliente y (B) con procesamiento descrito en esta invención con laminado y posterior prensado en caliente. Fig. 6. PEMFC H 2 /O 2 monocell tests at a temperature of 60 e C, 100% relative humidity and atmospheric pressure of a polymeric, inorganic and hybrid organic-inorganic membrane (A) with conventional pressing MEA processing hot and (B) with processing described in this invention with lamination and subsequent hot pressing.
Fig. 7. Ensayo en monocelda PEMFC H2/O2 a una temperatura de 60eC, 100% de humedad relativa y presión atmosférica de una membrana híbrida orgánico-inorgánica con procesamiento de MEA convencional de prensado en caliente y procesamiento descrito en esta invención con laminado y posterior prensado en caliente. EJEMPLOS Fig. 7. PEMFC H 2 /O 2 single-cell test at a temperature of 60 e C, 100% relative humidity and atmospheric pressure of an organic-inorganic hybrid membrane with conventional hot-pressing MEA processing and processing described in this invention with lamination and subsequent hot pressing. EXAMPLES
A continuación, se ¡lustrará la invención mediante unos ensayos realizados por los inventores, que pone de manifiesto la efectividad del producto de la invención. Next, the invention will be illustrated through tests carried out by the inventors, which demonstrate the effectiveness of the product of the invention.
Ejemplo 1 : Naturaleza de las membranas usadas para el ensamblaje de la unidad MEA Example 1: Nature of the membranes used for the assembly of the MEA unit
Se preparan membranas de naturaleza polimérica, inorgánica e híbrida orgánica- inorgánica. Membranes of polymeric, inorganic and hybrid organic-inorganic nature are prepared.
(1 ) Las membranas comerciales basadas en polímeros perfluorosulfonados (tipo Nation®) o en polímeros ionómeros de cadena hidrocarbonada se adquieren de una suministradora y se usan según la hoja técnica del producto sin ninguna modificación adicional. (1) Commercial membranes based on perfluorosulfonated polymers (Nation® type) or hydrocarbon chain ionomeric polymers are purchased from a supplier and used according to the product technical sheet without any additional modification.
(2) Las membranas poliméricas ionómeras basadas en copolímeros de bloque con grupos estireno sulfonados se preparan a partir de un copolímero tribloque de estireno-etileno-butileno-estireno (SEBS) con 32% en peso de unidades de estireno el cual se adquiere en Repsol con el nombre comercial Calprene CH-6120. Las membranas poliméricas de SEBS se preparan por colaje en cinta a partir de soluciones de cloroformo utilizando la técnica Dr Blade (BYK Instruments). La reacción de sulfonación heterogénea de SEBS (s-SEBS) se realiza sumergiendo las membranas poliméricas en una solución 0,3 M de clorosulfonato de trimetilsililo en dicloroetano (DCE) durante 2 horas. (2) Ionomeric polymer membranes based on block copolymers with sulfonated styrene groups are prepared from a triblock copolymer of styrene-ethylene-butylene-styrene (SEBS) with 32% by weight of styrene units which is purchased from Repsol. with the trade name Calprene CH-6120. SEBS polymeric membranes are prepared by tape collage from chloroform solutions using the Dr Blade technique (BYK Instruments). The heterogeneous sulfonation reaction of SEBS (s-SEBS) is performed by immersing the polymeric membranes in a 0.3 M solution of trimethylsilyl chlorosulfonate in dichloroethane (DCE) for 2 hours.
(3) Las soluciones sol-gel inorgánicas precursoras de las membranas inorgánicas se preparan utilizando fosfato de trimetilo (PO(OCH3)3, TMP), tetrapropóxido de circonio (Zr(OC3H7)4, TPZr) de Aldrich, ortosilicato de tetraetilo (Si(OC2H5)4, TEOS) de Merck y acetilacetona (C5H8O2, acac) de Fluka. Otros químicos utilizados fueron propanol como solvente de solución sol-gel (C3H8O) y agua acidulada (HCI 0.1 N) como catalizador de reacción sol-gel. Las membranas se preparan por colaje en moldes de Teflon (PTFE) dejando gelificar a 50 eC durante varios días en función del espesor final deseado. Diferentes composiciones se han probado, siendo la composición preferida la que mantiene la relación molar 40S¡02-40P205-20Zr02. Se puede utilizar una proporción % molar de P2O5 de 25-60%, de ZrO2 entre el 25- 30% y de S¡02 entre el 50-10%. (4) Membranas híbridas orgánico-inorgánicas basadas en s-SEBS y modificadas con soluciones sol-gel inorgánicas del sistema de óxidos ternarios SiO2-P2O5-ZrO2. Las membranas se preparan por el proceso de infiltración. Las membranas de s-SEBS se hinchan previamente en H2SO4 1 N a 80 °C durante 2 h y luego se sumergen en la solución de 40S¡02-40P205-20Zr02 a 80 °C durante diferentes tiempos. El tiempo preferible es de 10 minutos de infiltración. Al final del tratamiento, las membranas se limpian con etanol y se secan a 50 °C durante 1 h y a 120 °C durante 2 h para garantizar la formación de los geles. Finalmente, las membranas híbridas se limpian con etanol a 80 °C durante 2 h y se secan a 80 °C durante 1 h. Las muestras secas infiltradas muestran un aumento de área entre 42% y 1 17%, y espesores de alrededor de 45-55 pm dependiendo del tiempo de infiltración. (3) Inorganic sol-gel solutions precursors of inorganic membranes are prepared using trimethyl phosphate (PO(OCH 3 )3, TMP), zirconium tetrapropoxide (Zr(OC 3 H 7 )4, TPZr) from Aldrich, orthosilicate tetraethyl (Si(OC 2 H 5 )4, TEOS) from Merck and acetylacetone (C 5 H 8 O 2 , acac) from Fluka. Other chemicals used were propanol as sol-gel solution solvent (C 3 H 8 O) and acidulated water (HCl 0.1 N) as sol-gel reaction catalyst. The membranes are prepared by casting in Teflon (PTFE) molds, allowing them to gel at 50 ° C for several days depending on the desired final thickness. Different compositions have been tested, the preferred composition being the one that maintains the molar ratio 40S¡0 2 -40P 2 0 5 -20Zr0 2 . A molar % proportion of P 2 O 5 of 25-60%, of ZrO 2 between 25-30% and of S¡0 2 between 50-10% can be used. (4) Organic-inorganic hybrid membranes based on s-SEBS and modified with inorganic sol-gel solutions of the SiO 2 -P2O 5 -ZrO 2 ternary oxide system. The membranes are prepared by the infiltration process. The s-SEBS membranes are pre-swollen in 1 N H 2 SO 4 at 80 °C for 2 h and then immersed in the 40S¡0 2 -40P 2 0 5 -20Zr0 2 solution at 80 °C for different times. The preferable time is 10 minutes of infiltration. At the end of the treatment, the membranes are cleaned with ethanol and dried at 50 °C for 1 h and 120 °C for 2 h to ensure the formation of the gels. Finally, the hybrid membranes are cleaned with ethanol at 80 °C for 2 h and dried at 80 °C for 1 h. The dry infiltrated samples show an increase in area between 42% and 1 17%, and thicknesses of around 45-55 pm depending on the infiltration time.
Todas las membranas se cortan a un tamaño ligeramente superior al del área activa del electrodo a usar en la MEA. Por ejemplo, si el área activa es de 5 cm2, los electrodos serán de 2.24 x 2.24 cm2 y las dimensiones mínimas de la membrana de 3 x 3 cm2.All membranes are cut to a size slightly larger than the active area of the electrode to be used in the MEA. For example, if the active area is 5 cm 2 , the electrodes will be 2.24 x 2.24 cm 2 and the minimum membrane dimensions will be 3 x 3 cm 2 .
Las membranas poliméhcas e híbridas son homogéneas, transparentes sin grietas ni defectos. Polymehcas and hybrid membranes are homogeneous, transparent without cracks or defects.
Ejemplo 2: Obtención de la unidad MEA en conformación CCS (Catalyst Coated on Substrate) Example 2: Obtaining the MEA unit in CCS (Catalyst Coated on Substrate) conformation
Se preparan ensamblajes membrana-electrodos usando membranas ionómeras de cualquier naturaleza (tanto poliméhcas puras como híbridas orgánico-inorgánicas) y electrodos en la configuración CCS: Membrane-electrode assemblies are prepared using ionomeric membranes of any nature (both pure polymeric and organic-inorganic hybrids) and electrodes in the CCS configuration:
1. Los electrodos (4a y 4b) en este ejemplo están compuestos por una capa difusora de gases GDL comercial (Sigracet BC39 de SGL) y una capa catalítica depositada por pulverizado sobre la GDL. La capa catalítica contiene entre 0.9- 1 .0 mg Pt/cm2 y se han usado electrodos simétricos en ánodo y cátodo. 1. The electrodes (4a and 4b) in this example are composed of a commercial GDL gas diffusion layer (Sigracet BC39 from SGL) and a catalytic layer spray deposited on the GDL. The catalytic layer contains between 0.9-1.0 mg Pt/cm 2 and symmetrical electrodes have been used on the anode and cathode.
2. El ensamblaje se realiza preparando la funda de plastificado (1 ) (polipropileno biohentado (BOPP) con una capa de copolímero de etileno-acetato de vinilo (EVA)), haciéndole una ventana central (2) del tamaño del área activa que vaya a tener la unidad MEA (Figura 1 ). 3. Se coloca la membrana (3) en el interior de la funda de plastificado (1 ) como se indica en la Figura 2. Es necesario centrarla bien respecto a la ventana de la funda evitando arrugas para que el plastificado sea adecuado y no se produzcan fallos en el proceso. 2. The assembly is carried out by preparing the plastic cover (1) (biohented polypropylene (BOPP) with a layer of ethylene-vinyl acetate copolymer (EVA)), making a central window (2) the size of the active area that goes to have the MEA unit (Figure 1). 3. The membrane (3) is placed inside the laminating sleeve (1) as indicated in Figure 2. It is necessary to center it well with respect to the window of the sleeve, avoiding wrinkles so that the laminating is adequate and does not produce failures in the process.
4. Se cubre el conjunto funda-membrana con papel protector tipo cebolla o similar para que éste absorba la presión del laminado, evitando además problemas de obstrucción y atasco en la laminadora. 4. The cover-membrane assembly is covered with onion-type protective paper or similar so that it absorbs the pressure of the laminate, also avoiding problems of obstruction and jamming in the laminator.
5. Se procede a la etapa del plastificado introduciendo el conjunto funda-membrana cubierto con el papel protector en la laminadora previamente calentada a 80 eC. El plastificado debe sellar la membrana respetando su dimensionalidad respecto a la funda de plastificado usada (Figura 3.A). 5. We proceed to the laminating stage by introducing the cover-membrane assembly covered with the protective paper into the laminator previously heated to 80 e C. The lamination must seal the membrane respecting its dimensionality with respect to the laminating cover used (Figure 3. TO).
6. En la Figura 3.B se muestra cómo se colocan los electrodos (4a y 4b) a ambos lados de la membrana plastificada, enfrentándolos perfectamente a la ventana de área activa y teniendo en cuenta que cada electrodo siempre tiene que ser ligeramente más grande que la ventana (2) de la membrana plastificada (1 ), es decir, cada electrodo (4) siempre debe superponerse ligeramente a la ventana (2) del plastificado, reduciéndose así el área activa de la MEA entre un 3 y 8 %, respecto al proceso de ensamblaje sin etapa de laminación. 6. Figure 3.B shows how the electrodes (4a and 4b) are placed on both sides of the plasticized membrane, facing them perfectly to the active area window and taking into account that each electrode always has to be slightly larger. that the window (2) of the plasticized membrane (1), that is, each electrode (4) must always slightly overlap the window (2) of the plasticized membrane, thus reducing the active area of the MEA between 3 and 8%. regarding the assembly process without lamination stage.
7. La Figura 3.C muestra la vista lateral de la MEA final, después de los procesos de prensado en caliente y enfriamiento. La Figura 4 muestra una vista cenital de la MEA final. El prensado se realiza a una temperatura de 100 eC a una presión de 15 bar durante 3 min en una prensa hidráulica Collin P200. El proceso de enfriamiento se realiza utilizando los cartuchos de enfriamiento de la prensa hidráulica Collin P200 a una presión de 15 bar durante 3 minutos. 7. Figure 3.C shows the side view of the final MEA, after the hot pressing and cooling processes. Figure 4 shows a top-down view of the final MEA. Pressing is carried out at a temperature of 100 e C at a pressure of 15 bar for 3 min in a Collin P200 hydraulic press. The cooling process is carried out using the cooling cartridges of the Collin P200 hydraulic press at a pressure of 15 bar for 3 minutes.
Ejemplo 3: Mejoras en la eficiencia de la pila (curvas l-V y curvas de densidad de potencia) en unidades MEA ensambladas con el procedimiento descrito en esta invención. Example 3: Improvements in stack efficiency (l-V curves and power density curves) in MEA units assembled with the procedure described in this invention.
Se demuestra como el uso de la presente invención mejora el rendimiento electroquímico en la pila independientemente de la naturaleza de la membrana y de los electrodos usados en el ensamblaje. Para ello se determinan las curvas de polarización y densidad de potencia de diferentes unidades MEA ensambladas en un caso por el método tradicional de prensado en caliente y en otro, utilizando el presente procedimiento de invención de laminado y posterior prensado con el fin de comparar los resultados. It is demonstrated how the use of the present invention improves the electrochemical performance in the cell regardless of the nature of the membrane and the electrodes used in the assembly. To do this, the polarization and power density curves of different MEA units assembled in one case by the traditional hot pressing method and another, using the present invention process of lamination and subsequent pressing in order to compare the results.
Los ensayos se han realizado en monoceldas comerciales ElectroChem® de 5 cm2 con placas bipolares de grafito con canales de flujo en diseño serpentín; estación de ensayos Scribner 850e, flujo de gases H2/O2 de 200 mL/min, 100% humedad relativa y presión atmosférica. The tests have been carried out in commercial ElectroChem® 5 cm 2 monocells with bipolar graphite plates with flow channels in a serpentine design; Scribner 850e testing station, H 2 /O 2 gas flow of 200 mL/min, 100% relative humidity and atmospheric pressure.
En el caso del Nation® (N1 12), usando 1.0 mg Pt/cm2 en cada electrodo y 80eC de temperatura de celda, la densidad de corriente máxima aumenta desde los 2700 mA/cm2 hasta los 2900 mA/cm2 en las MEAs laminadas, como se observa en la Figura 5. La densidad de potencia máxima también mejora levemente pasando de 922 mW/cm2 a 923 mW/cm2. In the case of Nation® (N1 12), using 1.0 mg Pt/cm 2 on each electrode and 80 e C cell temperature, the maximum current density increases from 2700 mA/cm 2 to 2900 mA/cm 2 in the laminated MEAs, as seen in Figure 5. The maximum power density also improves slightly, going from 922 mW/cm 2 to 923 mW/cm 2 .
En la figura 6 se compara el rendimiento de la membrana poliméhca pura s-SEBS con la membrana híbrida orgánico-inorgánica sSEBS-(40S¡02-40P205-20Zr02) con ambos procedimientos de ensamblaje: procedimiento tradicional de prensado en caliente (Figura 6.A) y procedimiento de la presente invención (Figura 6.B). Para la membrana poliméhca s-SEBS, la densidad de potencia máxima obtenida es de 300 mW/cm2 en la MEA convencional, sin embargo, en la MEA laminada usando el procedimiento descrito en la presente invención se obtiene una densidad de potencia máxima de 400 mW/cm2 (lo que corresponde a una mejora del 33%). Lo mismo ocurre para las membranas híbridas sSEBS-(40S¡02-40P205-20Zr02) infiltrada 5 minutos y sSEBS- (40S¡02-40P205-20Zr02) infiltrada 10 minutos que su densidad de potencia máxima pasa de 316 y 412 mW/cm2 con el método convencional de prensado en caliente a 430 y 504 mW/cm2 con el procesamiento descrito en esta invención lo que supone mejoras del 36 y 22 %, respectivamente. Este mayor rendimiento está relacionado directamente con el método de ensamblaje utilizado y la mejora de las interfases cuando se utiliza el procesamiento descrito en la presente invención. En la Figura 7 se puede comparar directamente esta mejora del rendimiento electroquímico cuando se utiliza en el procesamiento de la MEA la combinación de laminado y prensado en caliente, para el ejemplo preferido de membrana híbrida sSEBS-(40S¡02-40P205-20Zr02) infiltrada durante 10 minutos lo que supone una mejora de la densidad de potencia del 22%. Figure 6 compares the performance of the pure s-SEBS polymeric membrane with the organic-inorganic hybrid membrane sSEBS-(40S¡0 2 -40P 2 0 5 -20Zr0 2 ) with both assembly procedures: traditional pressing procedure in hot (Figure 6.A) and procedure of the present invention (Figure 6.B). For the s-SEBS polymeric membrane, the maximum power density obtained is 300 mW/cm 2 in the conventional MEA, however, in the laminated MEA using the procedure described in the present invention a maximum power density of 400 is obtained. mW/cm 2 (corresponding to a 33% improvement). The same occurs for the hybrid membranes sSEBS-(40S¡0 2 -40P 2 0 5 -20Zr0 2 ) infiltrated for 5 minutes and sSEBS- (40S¡0 2 -40P 2 0 5 -20Zr0 2 ) infiltrated for 10 minutes that their density maximum power goes from 316 and 412 mW/cm 2 with the conventional hot pressing method to 430 and 504 mW/cm 2 with the processing described in this invention, which represents improvements of 36 and 22%, respectively. This higher performance is directly related to the assembly method used and the improvement of the interfaces when the processing described in the present invention is used. In Figure 7, this improvement in electrochemical performance can be directly compared when the combination of lamination and hot pressing is used in MEA processing, for the preferred example of sSEBS-(40S¡0 2 -40P 2 0 5) hybrid membrane. -20Zr0 2 ) infiltrated for 10 minutes, which represents an improvement in power density of 22%.
Ejemplo 4: Evaluación post-mortem de la unidad MEA tras el ensayo electroquímico en la celda. Example 4: Post-mortem evaluation of the MEA unit after the electrochemical test in the cell.
El uso del procesamiento descrito en esta invención combinando el laminado con el prensado en caliente permite “la caracterización repetitiva” y el estudio post- mortem de las MEAs tras su evaluación electroquímica. Con un procesamiento común de prensado en caliente una vez realizado el ensayo electroquímico y desmontada la monocelda o stack, se obtenían MEAs despegadas en la mayoría de las veces y dañadas a fin de ensayo, sobre todo al ensayar membranas cuya naturaleza no es 100% polimérica. Esto producía una caída de rendimiento durante los ciclos ensayados y hacía imposible la reutilización de esas MEAs en otros ensayos (variando temperatura o humedad relativa). Sin embargo, usando el método de procesamiento descrito en esta presente invención, las MEAs laminadas se mantienen inalteradas tras ser ensayadas lo cual supone una mejora en el rendimiento electroquímico, se pueden volver a montar y ensayar para completar el estudio electroquímico y además se permite el estudio post-mortem de la MEA. The use of the processing described in this invention combining laminate with Hot pressing allows “repetitive characterization” and post-mortem study of the MEAs after their electrochemical evaluation. With a common hot pressing process, once the electrochemical test was carried out and the single cell or stack was disassembled, MEAs were obtained that were detached in most cases and damaged for testing purposes, especially when testing membranes whose nature is not 100% polymeric. . This produced a drop in performance during the tested cycles and made it impossible to reuse these MEAs in other tests (varying temperature or relative humidity). However, using the processing method described in this present invention, the laminated MEAs remain unchanged after being tested, which represents an improvement in the electrochemical performance, they can be reassembled and tested to complete the electrochemical study and also allow the post-mortem study of the MEA.

Claims

REIVINDICACIONES
1. Procedimiento de obtención de una unidad de ensamblaje membrana-electrodos (MEA) para pila de combustible caracterizada porque comprende las siguientes etapas: a) precalentar una laminadora que tenga un sistema de liberación de rodillos, durante al menos 4 minutos a una temperatura de entre 75 eC y 125 eC; b) agujerear una funda de plastificado (1 ) en su punto medio haciendo una ventana (2) con la medida del área activa deseada para la unidad MEA; c) colocar una membrana (3) en el interior de la funda de plastificado de la etapa (b), constituyendo el conjunto funda-membrana; d) cubrir con papel protector tipo cebolla el conjunto funda-membrana obtenido en (c); e) plastificar con la laminadora precalentada del paso (a) el conjunto funda- membrana obtenido en (d) a una temperatura entre 75 y 125 eC; f) retirar manualmente el papel protector tipo cebolla del producto laminado obtenido en (e), quedando la membrana laminada; g) colocar dos electrodos (4a y 4b) en forma de sándwich sobre la membrana laminada obtenida en la etapa (f) enfrentándolos al hueco de la ventana libre de funda de plastificado creada en (b), donde el tamaño del perímetro de dichos electrodos es superior en perímetro al de la ventana de la funda de plastificado; h) prensar el laminado obtenido en (g) a una temperatura de entre 100 eC y 160 eC, a una presión de entre 8 bar y 20 bar durante al menos 3 min; y i) enfriar hasta una temperatura de entre 20 eC y 30eC, el ensamblaje obtenido en (h) aplicando una presión entre 8 bar y 20 bar durante al menos 3 minutos. 1. Procedure for obtaining a membrane-electrode assembly unit (MEA) for a fuel cell characterized in that it comprises the following stages: a) preheat a laminator that has a roller release system, for at least 4 minutes at a temperature of between 75 e C and 125 e C; b) hole a plastic cover (1) at its midpoint making a window (2) with the measurement of the desired active area for the MEA unit; c) placing a membrane (3) inside the plastic cover of step (b), constituting the cover-membrane assembly; d) cover the sheath-membrane assembly obtained in (c) with onion-type protective paper; e) laminate with the preheated laminator from step (a) the cover-membrane assembly obtained in (d) at a temperature between 75 and 125 e C; f) manually remove the onion-type protective paper from the laminated product obtained in (e), leaving the laminated membrane; g) place two electrodes (4a and 4b) in a sandwich shape on the laminated membrane obtained in step (f) facing them to the gap of the window free of plastic sheath created in (b), where the size of the perimeter of said electrodes It is larger in perimeter than the window in the plastic case; h) pressing the laminate obtained in (g) at a temperature of between 100 e C and 160 e C, at a pressure of between 8 bar and 20 bar for at least 3 min; and i) cool to a temperature between 20 e C and 30 e C, the assembly obtained in (h) by applying a pressure between 8 bar and 20 bar for at least 3 minutes.
2. Procedimiento según la reivindicación 1 , donde antes de la etapa (a), se realiza una etapa previa de preparación de los componentes de la unidad MEA: la membrana (3) y los electrodos (4a y 4b), al tamaño deseado, y mediante un método CCS o un método CCM. 2. Procedure according to claim 1, where before step (a), a previous stage of preparation of the components of the MEA unit is carried out: the membrane (3) and the electrodes (4a and 4b), to the desired size, and by a CCS method or a CCM method.
3. Procedimiento según cualquiera de las reivindicaciones 1 ó 2, donde la membrana (3) se selecciona de entre membranas ionómeras basadas en polímeros perfluorosulfonados, membranas ionómeras basadas en polímeros de cadena hidrocarbonada, membranas híbridas orgánico-inorgánicas basadas en polímeros perfluorosulfonados, membranas híbridas orgánico-inorgánicas basadas en polímeros ionómeros de cadena hidrocarbonada, membranas ionómeras basadas en copolímeros de bloque con grupos estireno sulfonados y membranas híbridas orgánico-inorgánicas basadas en copolímeros de bloque con grupos estireno sulfonados. 3. Method according to any of claims 1 or 2, wherein the membrane (3) is selected from ionomeric membranes based on polymers. perfluorosulfonated, ionomeric membranes based on hydrocarbon chain polymers, organic-inorganic hybrid membranes based on perfluorosulfonated polymers, organic-inorganic hybrid membranes based on hydrocarbon chain ionomer polymers, ionomeric membranes based on block copolymers with sulfonated styrene groups and organic-hybrid membranes inorganic based on block copolymers with sulfonated styrene groups.
4. Procedimiento según la reivindicación 3, donde la membrana (3) tienen una capa catalítica depositada por el método CCM mediante un método de deposición, química o física, preferiblemente aerografiado, serigrafía, decal transfer, electrodeposición, pulverización con haz de iones o pulverización catódica magnética. 4. Method according to claim 3, wherein the membrane (3) has a catalytic layer deposited by the CCM method using a deposition, chemical or physical method, preferably airbrushing, screen printing, decal transfer, electrodeposition, ion beam spraying or spraying. magnetic cathode.
5. Procedimiento según cualquiera de las reivindicaciones 1 a 4, donde los electrodos (4a y 4b) son seleccionados de entre electrodos con capa de difusión de gases (GDL) fabricada en papel, fieltro, fibras o telas de carbón con o sin capa microporosa (MPL), estando la capa catalítica depositada mediante un método de deposición ya sea químico o físico, preferiblemente aerografía, serigrafía, electrodeposición, deposición química en estado de vapor, pulverización con haz de iones o pulverización catódica magnética. 5. Method according to any of claims 1 to 4, wherein the electrodes (4a and 4b) are selected from electrodes with a gas diffusion layer (GDL) made of paper, felt, carbon fibers or fabrics with or without a microporous layer. (MPL), the catalytic layer being deposited by either a chemical or physical deposition method, preferably airbrushing, screen printing, electrodeposition, chemical vapor deposition, ion beam sputtering or magnetic sputtering.
6. Procedimiento según cualquiera de las reivindicaciones 1 a 5, donde la funda de plastificado (1 ) de la etapa (b) se selecciona de entre polipropileno biorientado (BOPP), policarbonatos, poliuretanos o poliamidas. 6. Method according to any of claims 1 to 5, wherein the plasticizing sleeve (1) of step (b) is selected from bioriented polypropylene (BOPP), polycarbonates, polyurethanes or polyamides.
7. Procedimiento según la reivindicación 6, donde la funda de plastificado (1 ) es de polipropileno biorientado. 7. Procedure according to claim 6, wherein the plasticizing sleeve (1) is made of bioriented polypropylene.
8. Procedimiento según la reivindicación 7, donde la funda de plastificado (1 ) de polipropileno biorientado comprende un recubrimiento de un copolímero de etileno- acetato de vinilo (EVA), con espesores totales comprendidos entre 80 y 125 pm. 8. Method according to claim 7, wherein the plasticized cover (1) of bioriented polypropylene comprises a coating of an ethylene-vinyl acetate (EVA) copolymer, with total thicknesses between 80 and 125 pm.
9. Procedimiento según cualquiera de las reivindicaciones 1 a 8, donde el papel protector tipo cebolla de la etapa (d) es papel vegetal Parafilm con un gramaje que oscila entre 40 y 100 g/m2, contenido en fibras de algodón del 25 % en peso y resistencia a temperaturas de hasta 220 eC. 9. Method according to any of claims 1 to 8, wherein the onion-type protective paper of step (d) is Parafilm vegetable paper with a weight ranging between 40 and 100 g/m 2 , with a cotton fiber content of 25%. in weight and resistance to temperatures up to 220 e C.
10. Procedimiento según cualquiera de las reivindicaciones 1 a 9, donde el plastificado de la etapa (e) se realiza a una velocidad de entre 20 cm/min y 40 cm/min. 10. Method according to any of claims 1 to 9, wherein the laminating of step (e) is carried out at a speed of between 20 cm/min and 40 cm/min.
11. Procedimiento según cualquiera de las reivindicaciones 1 a 10, donde durante el plastificado se aplica una presión en la etapa (e) la cual reduce el espesor del conjunto funda-membrana obtenido entre un 3 y 7 % con respecto a la relación entre el espesor del conjunto funda-membrana a la entrada y a la salida de la laminadora. 11. Procedure according to any of claims 1 to 10, where during lamination a pressure is applied in step (e) which reduces the thickness of the sheath-membrane assembly obtained between 3 and 7% with respect to the ratio between the thickness of the sheath-membrane assembly at the entrance and exit of the laminator.
12. Procedimiento según cualquiera de las reivindicaciones 1 a 1 1 , donde el prensado de la etapa (h) se realiza entre una temperatura de 100 eC y 160 eC, a una presión de entre 8 bar y 20 bar durante al menos 3 min. 12. Procedure according to any of claims 1 to 1 1, wherein the pressing of step (h) is carried out between a temperature of 100 e C and 160 e C, at a pressure of between 8 bar and 20 bar for at least 3 min.
13. Procedimiento según cualquiera de las reivindicaciones 1 a 12, donde el enfriamiento de la etapa (i) se realiza con los cartuchos de enfriamiento de la prensa hidráulica durante un tiempo de al menos 3 minutos manteniendo una presión de entre 8 bar y 20 bar. 13. Procedure according to any of claims 1 to 12, wherein the cooling of stage (i) is carried out with the cooling cartridges of the hydraulic press for a time of at least 3 minutes maintaining a pressure of between 8 bar and 20 bar. .
14. Una unidad de ensamblaje membrana-electrodos que comprende una membrana que comprende en una membrana de intercambio iónico (3) y una capa catalítica, y dos electrodos a ambos lados de la membrana (4a y 4b) caracterizado por que la membrana además comprende una funda plastificada (1 ) que la recubre de un material seleccionado de entre polipropileno biorientado (BOPP), policarbonatos, poliuretanos o poliamidas, donde la funda además presenta un agujero en su punto medio haciendo una ventana (2) con la medida del área activa deseada para el MEA para conectar los electrodos y dicha membrana. 14. A membrane-electrode assembly unit that comprises a membrane that comprises an ion exchange membrane (3) and a catalytic layer, and two electrodes on both sides of the membrane (4a and 4b) characterized in that the membrane also comprises a plasticized case (1) that covers it with a material selected from bioriented polypropylene (BOPP), polycarbonates, polyurethanes or polyamides, where the case also has a hole at its midpoint making a window (2) with the measurement of the active area desired for the MEA to connect the electrodes and said membrane.
15. Unidad de ensamblaje membrana-electrodos según la reivindicación 14, donde la funda de plastificado (1 ) es de polipropileno biorientado y comprende un recubrimiento de un copolímero de etileno-acetato de vinilo (EVA), con espesores totales comprendidos entre 80 y 125 pm. 15. Membrane-electrode assembly unit according to claim 14, wherein the plastic sheath (1) is made of bioriented polypropylene and comprises a coating of an ethylene-vinyl acetate (EVA) copolymer, with total thicknesses between 80 and 125 p.m.
PCT/ES2023/070769 2022-12-22 2023-12-20 Method for obtaining a membrane electrode assembly (mea) unit in electrochemical devices WO2024134002A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006015147A2 (en) * 2004-07-30 2006-02-09 General Motors Corporation Edge-protected catalyst-coated membrane electrode assemblies
WO2012017225A1 (en) * 2010-08-03 2012-02-09 Johnson Matthey Plc Membrane structure
EP2479829A1 (en) * 2005-09-26 2012-07-25 Gore Enterprise Holdings, Inc. Solid polymer electrolyte and process for making same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006015147A2 (en) * 2004-07-30 2006-02-09 General Motors Corporation Edge-protected catalyst-coated membrane electrode assemblies
EP2479829A1 (en) * 2005-09-26 2012-07-25 Gore Enterprise Holdings, Inc. Solid polymer electrolyte and process for making same
WO2012017225A1 (en) * 2010-08-03 2012-02-09 Johnson Matthey Plc Membrane structure

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