Device for determining the ionic conductivity and resistance to oxygen and hydrogen transport of an ionically conductive polymer film

Abstract

A device for determining the ionic conductivity and resistance to oxygen and hydrogen transport of an ionically conductive polymer film (F), comprising: - a substrate (2), including a dielectric surface (20); - first and second interdigitated electrodes (E1, E2), arranged on the dielectric surface (20), made of an electrically conductive material; - a dielectric filling material (4), extending between the first and second interdigitated electrodes (E1, E2), so as to be flush with them and together form a flat receiving surface for the film (F); - means for injecting a gaseous stream of oxygen or hydrogen; - an electronic circuit, configured to measure physical quantities from which an ionic conductivity and a resistance to oxygen and hydrogen transport can be determined. Figure 6

Description

Title of the invention: Device for determining ionic conductivity and resistance to transport of dioxygen and dihydrogen of an ionic conductive polymer film Technical field

[0001] The invention relates to the technical field of devices for measuring ion and gas transport properties in an ionic conductive polymer film. More specifically, the ions concerned are: (i) hydroxide ions OH (also called hydroxyl ions), and (ii) hydrogen ions, which may be hydride anions H, or hydrons H+ such as protons (without neutrons).

[0002] The gases concerned are dioxygen O2 and dihydrogen H2.

[0003] The invention finds its application in particular in the design of membranes for different types of fuel cells or different types of electrolysers, for example a PEMFC proton exchange membrane fuel cell (Proton Exchange Membrane Fuel Cell), an AEMFC anion exchange membrane fuel cell (Anion Exchange Membrane Fuel Cell), a PEMWE proton exchange membrane electrolyser (Proton Exchange Membrane Water Electrolyzer), an AEMWE anion exchange membrane electrolyser (Anion Exchange Membrane Water Electrolyzer). State of the art

[0004] There are devices for determining the ionic conductivity (hydroxide ions OH and hydrogen ions H+) of an ionically conductive polymer film. It should be noted that we speak more specifically of proton conductivity in the case of hydrogen ions H+.

[0005] There are also devices for determining the resistance to transport of dioxygen O2 and dihydrogen H2 of an ionically conductive polymer film.

[0006] However, the person skilled in the art is looking for a device capable, on its own, of determining both an ionic conductivity and a resistance to the transport of dioxygen and dihydrogen of an ionic conductive polymer film.

[0007] In this regard, the document D. Chen et al., “Proton Conduction and Oxygen Diffusion in Ultra-Thin Nafion Films in PEM Fuel Cell: How Thin?”, Journal of The Electro-chemical Society, 166(2), F24-33, 2019 (hereinafter Dl), discloses a device for determining a proton conductivity (from electrochemical impedance spectroscopy measurements) and a resistance to the transport of dioxygen O2 (more precisely an oxygen permeability from limiting current measurements) of a ionic conductive polymer film.

[0008] Such a prior art device is not entirely satisfactory since the geometry of the electrodes used in DI can affect the reliability of the measurements, especially when the thickness of the ionic conductive polymer film is low, typically less than 100 nm. In other words, the ionic conductivity and transport resistances calculated from the measurements cannot be entirely attributed to the ionic conductive polymer film. DI mentions this problem (F25, left col.) and in particular uses a low concentration of dioxygen (of the order of 30 ppm) in order to minimize the resistance of the gas phase. Disclosure of the invention

[0009] The invention aims to remedy all or part of the aforementioned drawbacks. To this end, the invention relates to a device for determining an ionic conductivity and a resistance to the transport of dioxygen O2 and dihydrogen H2 of an ionic conductive polymer film, the device comprising: - a substrate, comprising a dielectric surface; - first and second interdigitated electrodes, arranged on the dielectric surface, made of an electrically conductive material; - a dielectric filler material extending over the dielectric surface between the first and second interdigitated electrodes, so as to be flush with the first and second interdigitated electrodes; the filler material and the first and second interdigitated electrodes being arranged so as to form a flat receiving surface for receiving the ionically conductive polymer film; - injection means, arranged to inject onto the receiving surface a gaseous flow of dioxygen O2 or dihydrogen H2, the gaseous flow preferably being humidified; - an electronic circuit, configured to: measuring a complex impedance between the first and second interdigitated electrodes in a frequency spectrum, so as to determine the ionic conductivity when the ionically conductive polymer film is disposed on the receiving surface; measuring a limit current flowing between the first and second interdigitated electrodes, so as to determine the resistance to the transport of dioxygen O2 and dihydrogen H2 when the ionic conductive polymer film is arranged on the receiving surface and is subjected to the gas flow of dioxygen O2 or dihydrogen H2 respectively injected by the injection means.

[0010] Thus, such a device according to the invention makes it possible to improve the reliability of the measurements compared to the state of the art, thanks to the first and second interdigitated electrodes and to the dielectric filling material forming a receiving surface. plane. Such an arrangement makes it possible to reduce the impact of the electrodes on the measured complex impedance and the measured limiting current, which is particularly significant when the thickness of the ionic conductive polymer film is low, typically less than 100 nm. Indeed, the inhomogeneities of the receiving surface present in DI (i.e. step height between the upper surface of the electrodes and the upper surface of the SiO) can lead to significant local variations in the current density, and thereby increase the impedance, particularly when the thickness of the ionic conductive polymer film is low, typically less than 100 nm.

[0011] The device according to the invention may comprise one or more of the following characteristics.

[0012] According to a characteristic of the invention, the receiving surface has a roughness less than or equal to 10 nm RMS, preferably less than or equal to 5 nm RMS.

[0013] Thus, an advantage provided by such surface roughness is to limit surface irregularities which can cause significant local variations in current density.

[0014] According to a characteristic of the invention, the first and second interdigitated electrodes have a geometry defined by: - a total number of tracks, noted “N”; - a distance, denoted “D”, between the first and second electrodes; - a width of the tracks, noted “1”, and an effective length of the tracks, noted “L”, defined in the plan of the reception surface; - a distance, denoted “i”, between the first electrode and a track of the second electrode, or between the second electrode and a track of the first electrode, “i” verifying the formula: » — XhL; - a distance, denoted “d”, between a track of the first electrode and an adjacent track of the second electrode, or between a track of the second electrode and an adjacent track of the first electrode; - a thickness of the tracks, noted “e”, defined according to the normal to the surface of the substrate.

[0015] According to a characteristic of the invention, the geometry of the first and second interdigitated electrodes is adapted as a function of a predetermined value of an electrical resistance of the ionic conductive polymer film, so that the complex impedance measured by the electronic circuit has a characteristic frequency less than or equal to 1 MHz, the predetermined value of the electrical resistance of the ionic conductive polymer film being less than or equal to 2 MΩ, preferably less than or equal to 1 MΩ.

[0016] Thus, an advantage provided is to make the capacitive effects negligible compared to the resistive effects, in order to improve the reliability of the measurements.

[0017] According to a characteristic of the invention, the geometry of the first and second interdigitated electrodes is adapted so that “i” verifies the formula: i Z-10 d.

[0018] Thus, an advantage provided is to limit measurement errors and to slow down the degradation of the device.

[0019] According to a characteristic of the invention, the geometry of the first and second interdigitated electrodes is adapted so that “d” is between 1 pm and 50 pm, preferably between 1 pm and 10 pm.

[0020] According to a characteristic of the invention, the geometry of the first and second interdigitated electrodes is adapted so that “N” is between 10 and 1000, preferably between 100 and 500.

[0021] According to a characteristic of the invention, the geometry of the first and second interdigitated electrodes is adapted so that “D” is between 1 mm and 10 mm, preferably between 5 mm and 10 mm.

[0022] According to a characteristic of the invention, the geometry of the first and second interdigitated electrodes is adapted so that “1” is between 1 pm and 10 pm.

[0023] According to a characteristic of the invention, the geometry of the first and second interdigitated electrodes is adapted so that “L” is between 1 mm and 20 mm, preferably between 5 mm and 10 mm.

[0024] According to a characteristic of the invention, the geometry of the first and second interdigitated electrodes is adapted so that “e” is between 50 nm and 500 nm, preferably between 100 nm and 200 nm.

[0025] According to a characteristic of the invention: - the surface of the substrate is coated with a dielectric layer which is made of a first dielectric material, preferably silicon dioxide SiO2; - the filling material is a second dielectric material, preferably identical to the first dielectric material.

[0026] According to a characteristic of the invention, the substrate is made of silicon.

[0027] According to a characteristic of the invention, the electrically conductive material, in from which the first and second interdigitated electrodes are made, is chosen from platinum Pt and iridium Ir.

[0028] Thus, platinum Pt has catalyst properties for oxygen evolution, oxygen reduction, hydrogen evolution, and hydrogen oxidation reactions. Iridium has catalyst properties for an oxygen evolution reaction.

[0029] According to a characteristic of the invention, the device comprises: - an ellipsometric measuring zone, arranged at a distance from the receiving surface; - ellipsometric measuring means, arranged to measure a thickness of the ionic conductive polymer film by ellipsometry when the ionic conductive polymer film is arranged in the ellipsometric measuring zone.

[0030] Thus, an advantage provided is to obtain an in situ measurement of the thickness of the ionic conductive polymer film, a parameter making it possible to calculate the ionic conductivity and the resistance to the transport of dioxygen O2 and dihydrogen H2.

[0031] Definitions

[0032] - The verb "determine" should not be interpreted as meaning to measure directly ionic conductivity and resistance to the transport of oxygen O2 and hydrogen H2. The determination of these quantities is obtained from measurements (complex impedance and limiting current), these measurements being processed (e.g. modeling, calculations) in order to determine these quantities.

[0033] - By "ionic conductivity" (unit: S / m), we mean the capacity of the film of Ionic conductive polymer to the conduction of hydroxide ions OH or hydrogen ions within it, that is, the ability to conduct electric current through the movement of hydroxide ions OH or hydrogen ions. We speak of proton conductivity for hydrogen ions H+ without neutrons.

[0034] - By "transport resistance" is meant a physical quantity of the film of ionic conductive polymer representative of the resistance to gas transport (dioxygen O2 and dihydrogen H2) within it and at the interfaces (with the interdigitated electrodes and with the gas). As non-limiting examples, we can cite as physical quantities the permeability, the diffusion coefficient and the resistances at the interfaces.

[0035] - By “film” is meant a thin layer with a thickness less than or equal to 500 nm.

[0036] - By "ionic conductive polymer" is meant a polymer capable of transporting ionic charges. The terms "ionomer" and "polyelectrolyte" are also used.

[0037] - By "substrate" is meant a self-supporting physical medium. A substrate may be a "slice" (also called "platelet", "wafer" in English) which generally comes in the form of a disc cut from an ingot of a crystalline material.

[0038] - By "dielectric" is meant a material having an electrical conductivity at 300 K less than or equal to 106 S / cm.

[0039] - By "interdigitated electrodes" is meant two electrodes arranged in a geometry like the fingers of two hands interlacing. The first electrode has a first set of parallel electrically conductive tracks (branches). The second electrode has a second set of parallel electrically conductive tracks (branches). The first and second electrodes are arranged so as to alternate a runway of the first set and a runway of the second set. The runways of the first set and the runways of the second set are parallel to each other, and spaced so as to follow one another in turn in a repeated manner. The “effective length” of a runway is not the length of the entire runway (i.e. the total length of the runway), but corresponds to the length of a first area of ​​the runway which faces an adjacent runway. The length of a second area of ​​the runway which does not face an adjacent runway is not taken into account in the effective length of the runway.

[0040] - By "electrically conductive material" is meant that the material has a electrical conductivity at 300 K greater than or equal to 102 S / cm.

[0041] - The expression "oxygen evolution reaction" is generally designated by the acronym OER (“Oxygen Evolution Reaction” in English).

[0042] - The expression "oxygen reduction reaction" is generally designated by the acronym ORR (“Oxygen Reduction Reaction” in English).

[0043] - The expression "hydrogen evolution reaction" is generally designated by the acronym HER (“Hydrogen Evolution Reaction” in English).

[0044] - The expression "hydrogen oxidation reaction" is generally designated by the acronym HOR (“Hydrogen Oxidation Reaction” in English).

[0045] - By "flat receiving surface" is meant a flatness within the tolerances usual linked to the experimental manufacturing conditions, and not perfectly in the mathematical sense of the term.

[0046] - By "limit current" is meant the maximum value of a current that can flow between the first and second interdigitated electrodes, passing through the ionic conductive polymer film when a gas flow is injected.

[0047] - By "RMS" is meant the root mean square of the surface roughness. RMS is the acronym for “Root Mean Square” in English.

[0048] - By "predetermined" is meant that the value of the electrical resistance of the film of ionic conductive polymer is determined prior to use of the device according to the invention.

[0049] - By "characteristic frequency" is meant a frequency of the impedance complex allowing to distinguish (eg maximum, inflection point) a transition or a difference of regimes in the electrochemical response of the device with the ionic conductive polymer film.

[0050] - The values ​​X and Y expressed using the expressions “between X and Y” or “included between X and Y” are included in the defined range of values. Brief description of the drawings

[0051] Other features and advantages will become apparent in the detailed description of different embodiments of the invention, the description being accompanied by examples and references to the attached drawings.

[0052] [Fig. 1] is a schematic perspective view, in transparency, of a device according to the invention.

[0053] [Fig.2] is a schematic top view, in transparency, of a device according to the invention.

[0054] [Fig.3] is a partial schematic top view of a device according to the invention, illustrating the first and second interdigitated electrodes and the ellipsometric measurement area. The dielectric layer and the filler material are not illustrated for readability.

[0055] [Fig.4] is a schematic top view on an enlarged scale of the first and second interdigitated electrodes equipping a device according to the invention.

[0056] [Fig.5] is a partial schematic sectional view of a device according to the invention, illustrating a portion of the substrate, the dielectric layer, the filler material and a portion of the first and second interdigitated electrodes.

[0057] [Fig.6] is a schematic view similar to [Fig.5], illustrating the presence of a film of ionic conductive polymer on the receiving surface.

[0058] It should be noted that the drawings described above are schematic, and are not necessarily to scale for the sake of readability and to simplify their understanding. The sections are made along the normal to the surface of the substrate. Detailed description of the implementation methods

[0059] Elements that are identical or provide the same function will bear the same references for the different embodiments, for the sake of simplification.

[0060] An object of the invention is a device 1 for determining an ionic conductivity and a resistance to the transport of dioxygen O2 and dihydrogen H2 of a film F of ionic conductive polymer, the device 1 comprising: - a substrate 2, comprising a dielectric surface 20; - first and second interdigitated electrodes E1, E2, arranged on the dielectric surface 20, made of an electrically conductive material; - a dielectric filling material 4, extending on the dielectric surface 20 between the first and second interdigitated electrodes El, E2, so as to be flush with the first and second interdigitated electrodes El, E2; the filling material 4 and the first and second interdigitated electrodes El, E2 being arranged so as to form a flat receiving surface S for receiving the film F of ionically conductive polymer; - injection means 5, arranged to inject onto the receiving surface S a gaseous flow of dioxygen O2 or dihydrogen H2, the gaseous flow preferably being humidified; - an electronic circuit, configured to: measuring a complex impedance between the first and second interdigitated electrodes E1, E2 in a frequency spectrum, so as to determine the ionic conductivity when the ionic conductive polymer film F is arranged on the receiving surface S; measuring a limit current flowing between the first and second interdigitated electrodes E1, E2, so as to determine the resistance to the transport of oxygen O2 and hydrogen H2 when the film F of ionic conductive polymer is arranged on the receiving surface S and is subjected to the gas flow of oxygen O2 or hydrogen H2 respectively injected by the injection means 5.

[0061] Substrate

[0062] The substrate 2 comprises a dielectric surface 20. The substrate 2 is electrically insulated from the first and second interdigitated electrodes E1, E2.

[0063] According to a first embodiment, the substrate 2 is made of a first dielectric material, the surface 20 of the substrate 2 then being intrinsically dielectric.

[0064] According to a second embodiment, the substrate 2 is not made of a dielectric material, in which case the surface 20 of the substrate is coated with a dielectric layer 3, so that the surface 20 of the substrate 1 is extrinsically dielectric.

[0065] The substrate 2 may be made of a semiconductor material. By way of non-limiting example, the substrate 2 is made of silicon. The dielectric layer 3 is made of a first dielectric material. The first dielectric material is preferably silicon dioxide SiO2.

[0066] Electrodes

[0067] The first and second interdigitated electrodes El, E2 are arranged on the dielectric surface 20. More specifically, the first and second interdigitated electrodes El, E2 may be arranged on a surface of the dielectric layer 3 coating the surface 20 of the substrate 2. It is possible to provide a bonding layer (not illustrated) extending between the first and second interdigitated electrodes El, E2 and the dielectric layer 3. By way of non-limiting example, the bonding layer may be made of titanium Ti. The first and second interdigitated electrodes El, E2 have an upper surface.

[0068] The first and second interdigitated electrodes E1, E2 are made of an electrically conductive material. The electrically conductive material is advantageously a catalyst for at least one of the reactions of oxygen evolution, oxygen reduction, hydrogen evolution, and hydrogen oxidation. In this regard, the electrically conductive material is advantageously chosen from platinum Pt and iridium Ir. Platinum Pt is a catalyst for the reactions oxygen evolution, oxygen reduction, hydrogen evolution, and hydrogen oxidation. Iridium Ir is a catalyst for an oxygen evolution reaction.

[0069] The first and second interdigitated electrodes E1, E2 have a geometry defined by: - a total number of tracks, noted “N”; - a distance, noted “D”, between the first and second electrodes E1, E2; - a width of the tracks, noted “1”, and an effective length of the tracks, noted “L”, defined in the plane of the reception surface S; - a distance, denoted “i”, between the first electrode El and a track of the second electrode E2, or between the second electrode E2 and a track of the first electrode El, “i” verifying the formula: / = ; i 2 - a distance, denoted “d”, between a track of the first electrode El and an adjacent track of the second electrode E2, or between a track of the second electrode E2 and an adjacent track of the first electrode El; - a thickness of the tracks, noted “e”, defined according to the normal to the surface 20 of the substrate 2.

[0070] The geometry of the first and second interdigitated electrodes E1, E2 is advantageously adapted so that “N” is between 10 and 1000, preferably between 100 and 500.

[0071] The geometry of the first and second interdigitated electrodes E1, E2 is advantageously adapted so that “D” is between 1 mm and 10 mm, preferably between 5 mm and 10 mm.

[0072] The geometry of the first and second interdigitated electrodes E1, E2 is advantageously adapted so that “1” is between 1 pm and 10 pm.

[0073] The geometry of the first and second interdigitated electrodes E1, E2 is advantageously adapted so that “L” is between 1 mm and 20 mm, preferably between 5 mm and 10 mm.

[0074] The geometry of the first and second interdigitated electrodes E1, E2 is advantageously adapted so that “i” verifies the formula: 10 J.

[0075] The geometry of the first and second interdigitated electrodes E1, E2 is advantageously adapted so that “d” is between 1 pm and 50 pm, preferably between 1 pm and 10 pm.

[0076] The geometry of the first and second interdigitated electrodes E1, E2 is advantageously adapted so that “e” is between 50 nm and 500 nm, preferably between 100 nm and 200 nm.

[0077] The geometry of the first and second interdigitated electrodes E1, E2 is advantageous suitably adapted according to a predetermined value of an electrical resistance of the ionic conductive polymer film F, so that the complex impedance measured by the electronic circuit has a characteristic frequency less than or equal to 1 MHz. The predetermined value of the electrical resistance of the ionic conductive polymer film F is less than or equal to 2 MΩ, preferably less than or equal to 1 MΩ. More precisely, the parameters "N", "1", "L" and "d" are advantageously chosen according to the predetermined value of an electrical resistance of the ionic conductive polymer film F, so that the complex impedance measured by the electronic circuit has a characteristic frequency less than or equal to 1 MHz.

[0078] Filling material

[0079] The filling material 4 is dielectric. In other words, the filling material 4 is a second dielectric material, preferably identical to the first dielectric material. However, the second dielectric material may be different from the first dielectric material.

[0080] The filling material 4 has an upper surface. The filling material 4 extends over the dielectric surface 20 between the first and second interdigitated electrodes El, E2, so as to be flush with the first and second interdigitated electrodes El, E2. The filling material 4 may extend over the dielectric layer 3 between the first and second interdigitated electrodes El, E2, so as to be flush with the first and second interdigitated electrodes El, E2. More specifically, the filling material 4 extends over the surface of the dielectric layer 3, between the first and second interdigitated electrodes El, E2, so as to be flush with the first and second interdigitated electrodes El, E2. In other words, the upper surface of the filling material 4 and the upper surface of the first and second interdigitated electrodes El, E2 are coplanar.

[0081] The filling material 4 and the first and second interdigitated electrodes E1, E2 are arranged so as to form a flat receiving surface S for receiving the film F of ionic conductive polymer. The receiving surface S advantageously has a roughness less than or equal to 10 nm RMS, preferably less than or equal to 5 nm RMS.

[0082] An example of forming the filler material 4 is to deposit the filler material through a mask by physical vapor deposition. Another possibility is to deposit the filler material 4 by chemical vapor deposition, with precursor gases reacting on the surface of the dielectric layer 3. Then it is possible to carry out a planarization of the deposited filler material 4, for example by chemical-mechanical polishing, by grinding or using a plasma.

[0083] Injection means

[0084] The injection means 5 are arranged to inject onto the receiving surface S a gaseous flow of dioxygen O2 or dihydrogen H2. The gaseous flow is preferably humidified. The gaseous flow is preferably diluted with an inert gas such as dinitrogen N2, helium He, argon Ar.

[0085] The device 1 advantageously comprises an enclosure 10 successively comprising (from bottom to top) first, second, third and fourth compartments C1, C2, C3, C4.

[0086] The enclosure 10 has a controlled atmosphere, in particular in terms of temperature, composition of the injected gases and humidity level. In this regard, the enclosure 10 may be equipped with a temperature sensor T such as a thermocouple.

[0087] The first compartment C1 may comprise a water circuit with a water inlet IW and a water outlet OW. The water circuit is advantageously provided with baffles arranged to improve the efficiency of the water flow, for example by avoiding turbulent flow. The second compartment C2 is equipped with the substrate 2 and a gas outlet OG. The third compartment C3 is provided with a gas inlet IG and injection means 5. The injection means 5 advantageously comprise a circuit for injecting the gas flow, preferably humidified, comprising baffles arranged to maximize the extent of the gas flow on the receiving surface S. The injection means 5 are advantageously arranged to inject the gas flow, preferably humidified, onto the receiving surface S by convection. Injection by laminar flow of the gas flow is not entirely satisfactory.The fourth compartment C4 may comprise a water circuit with a water inlet IW and a water outlet OW. The water circuit is advantageously provided with baffles arranged to improve the efficiency of the water flow, for example by avoiding turbulent flow.

[0088] The enclosure 10 is advantageously provided with seals J arranged between the compartments C1, C2, C3, C4 in order to make the enclosure 10 sealed with the external environment.

[0089] Electronic circuit

[0090] The electronic circuit is configured to measure a complex impedance between the first and second interdigitated electrodes E1, E2 in a frequency spectrum. The ionic conductivity can then be determined from the complex impedance measurements when the ionic conductive polymer film F is arranged on the receiving surface S.

[0091] The fact of being able to determine the ionic conductivity from a processing of complex impedance measurements is known to those skilled in the art. An example of processing is described in document DI.

[0092] The electronic circuit is configured to measure a limit current flowing between the first and second interdigitated electrodes E1, E2. The current measurements limit can be carried out by cyclic voltammetry. The resistance to the transport of dioxygen O2 and dihydrogen H2 can then be determined from the measurements of the limit current when the film F of ionic conductive polymer is placed on the receiving surface S and is subjected to the gas flow of dioxygen O2 or dihydrogen H2 respectively injected by the injection means 5.

[0093] The fact of being able to determine the resistance to gas transport from a processing of the limit current measurements is known to those skilled in the art. An example of processing is described in document DI.

[0094] The electronic circuit is advantageously arranged outside the enclosure 10. The electronic circuit advantageously belongs to a potentiostat. The electronic circuit can be connected to the interdigitated electrodes E1, E2 using a connector 6, which can be a USB cable 60.

[0095] Ellipsometric measurement area

[0096] The device 1 advantageously comprises an ellipsometric measurement zone ZE, arranged at a distance from the receiving surface S.

[0097] The device 1 advantageously comprises ellipsometric measuring means (not shown), arranged outside the enclosure 10 to measure a thickness of the ionic conductive polymer film F by ellipsometry when the ionic conductive polymer film F is arranged in the ellipsometric measuring zone ZE. The ellipsometric measuring means comprise an ellipsometer, a polarized light source and a processing unit configured to process the ellipsometric data so as to obtain the thickness of the ionic conductive polymer film F.

[0098] Ionic conductive polymer

[0099] As non-limiting examples, the ionic conductive polymer may be chosen from Nafion™, a sulfonated or phosphonated derivative of polyetheretherketone (PEEK), a perfluorosulfonic acid (PFSA), polyacrylic acid (PAA). Generally, any polymer having an ion exchange group, cationic or anionic, may be considered.

[0100] The film F of ionic conductive polymer can be deposited on the receiving surface S by spin coating. A person skilled in the art knows how to adjust the experimental parameters (e.g. rotation speed, acceleration, rotation duration, flow rate, solvents, drying, etc.) of the spin coating depending on the nature and properties of the ionic conductive polymer.

[0101] By way of non-limiting example, the ionically conductive polymer film F may have a thickness of between a few nanometers and 250 nm.

[0102] Examples

[0103] When the ionic conductive polymer is Nafion™ with an average molar mass of 1000 g / mol with a thickness between 50 nm and 250 nm, the geometry of the first and second interdigitated electrodes El, E2 can be adapted so that “1” is equal to 10 pm and “d” is equal to 50 pm. “N” can be equal to 112. “L” can be equal to 6.2 mm.

[0104] When the ionic conductive polymer is Nation™ with an average molar mass of 1000 g / mol with a thickness between 5 nm and 50 nm, the geometry of the first and second interdigitated electrodes E1, E2 can be adapted so that “1” is equal to 4 pm and “d” is equal to 10 pm. “N” can be equal to 432. “L” can be equal to 6.2 mm.

[0105] The invention is not limited to the embodiments disclosed. Those skilled in the art are able to consider their technically operational combinations and to substitute equivalents for them.

Claims

Claims

1. Device (1) for determining an ionic conductivity and a resistance to transport of dioxygen O2 and dihydrogen H2 of a film (F) of ionic conductive polymer, the device (1) comprising: - a substrate (2), comprising a dielectric surface (20); - first and second interdigitated electrodes (El, E2), arranged on the dielectric surface (20), made of an electrically conductive material; - a dielectric filling material (4), extending on the dielectric surface (20) between the first and second interdigitated electrodes (El, E2), so as to be flush with the first and second interdigitated electrodes (El, E2); the filling material (4) and the first and second interdigitated electrodes (El, E2) being arranged so as to form a flat receiving surface (S) for receiving the film (F) of ionic conductive polymer;- injection means (5), arranged to inject onto the receiving surface (S) a gaseous flow of dioxygen O2 or dihydrogen H2, the gaseous flow preferably being humidified; - an electronic circuit, configured to: measure a complex impedance between the first and second interdigitated electrodes (El, E2) in a frequency spectrum, so as to determine the ionic conductivity when the film (F) of ionic conductive polymer is arranged on the receiving surface (S); measure a limit current flowing between the first and second interdigitated electrodes (El, E2), so as to determine the resistance to the transport of dioxygen O2 and to dihydrogen H2 when the film (F) of ionic conductive polymer is arranged on the receiving surface (S) and is subjected to the gaseous flow respectively of dioxygen O2 or dihydrogen H2 injected by the injection means (5).;

2. Device (1) according to claim 1, in which the receiving surface (S) has a roughness less than or equal to 10 nm RMS, preferably less than or equal to 5 nm RMS.

3. Device (1) according to claim 1 or 2, in which the first and second interdigitated electrodes (E1, E2) have a geometry defined by: - ​​a total number of tracks, denoted “N”; - a distance, denoted “D”, between the first and second electrodes (El, E2); - a width of the tracks, denoted "1", and an effective length of the tracks, denoted "L", defined in the plane of the receiving surface (S); - a distance, denoted "i", between the first electrode (El) and a track of the second electrode (E2), or between the second electrode (E2) and a track of the first electrode (El), "i" verifying the formula: •DL . ' ~ 2 ' - a distance, denoted "d", between a track of the first electrode (El) and an adjacent track of the second electrode (E2), or between a track of the second electrode (E2) and an adjacent track of the first electrode (El); - a thickness of the tracks, denoted "e", defined along the normal to the surface (S) of the substrate (2).

4. Device (1) according to claim 3, wherein the geometry of the first and second interdigitated electrodes (E1, E2) is adapted according to a predetermined value of an electrical resistance of the ionic conductive polymer film (F), so that the complex impedance measured by the electronic circuit has a characteristic frequency less than or equal to 1 MHz, the predetermined value of the electrical resistance of the ionic conductive polymer film (F) being less than or equal to 2 MΩ, preferably less than or equal to 1 MΩ.

5. Device (1) according to claim 3 or 4, wherein the geometry of the first and second interdigitated electrodes (El, E2) is adapted so that "i" verifies the formula: i 10 d.

6. Device (1) according to one of claims 3 to 5, in which the geometry of the first and second interdigitated electrodes (El, E2) is adapted so that “d” is between 1 pm and 50 pm, preferably between 1 pm and 10 pm.

7. Device (1) according to one of claims 3 to 6, in which the geometry of the first and second interdigitated electrodes (El, E2) is adapted so that “N” is between 10 and 1000, preferably between 100 and 500.

8. Device (1) according to one of claims 3 to 7, in which the geometry of the first and second interdigitated electrodes (El, E2) is adapted so that “D” is between 1 mm and 10 mm, preferably between 5 mm and 10 mm.

9. Device (1) according to one of claims 3 to 8, in which the

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13.

14.

15. geometry of the first and second interdigitated electrodes (El, E2) is adapted so that “1” is between 1 pm and 10 pm. Device (1) according to one of claims 3 to 9, in which the geometry of the first and second interdigitated electrodes (El, E2) is adapted so that “L” is between 1 mm and 20 mm, preferably between 5 mm and 10 mm. Device (1) according to one of claims 3 to 10, in which the geometry of the first and second interdigitated electrodes (El, E2) is adapted so that “e” is between 50 nm and 500 nm, preferably between 100 nm and 200 nm. Device (1) according to one of claims 1 to 11, in which: - the surface (20) of the substrate (2) is coated with a dielectric layer (3) which is made of a first dielectric material, preferably silicon dioxide SiO2; - the filling material (4) is a second dielectric material, preferably identical to the first dielectric material. Device (1) according to one of claims 1 to 12, in which the substrate (2) is made of silicon. Device (1) according to one of claims 1 to 13, in which the electrically conductive material, in which the first and second interdigitated electrodes (El, E2) are made, is chosen from platinum Pt and iridium Ir. Device (1) according to one of claims 1 to 14, comprising: - an ellipsometric measurement zone (ZE), arranged at a distance from the receiving surface (S); - ellipsometric measuring means, arranged to measure a thickness of the ionic conductive polymer film (F) by ellipsometry when the ionic conductive polymer film (F) is arranged in the ellipsometric measuring zone (ZE).

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