FIELD OF THE INVENTION

The invention relates to an electrochemical cell. The invention also relates to a method for analyzing a gas-diffusion electrode in an electrochemical cell. Further, the invention relates to an arrangement comprising one or more electrochemical cells.

BACKGROUND OF THE INVENTION

System and methods for controlling and analyzing electrochemical cells are known. US 5,763,765, for instance describes a method and apparatus to detect and locate perforations in membranes used in electrochemical cells. The membrane has first and second oppositely facing major planar surfaces. The first surface is exposed to a first reactant fluid, preferably a gaseous mixture comprising hydrogen, while the second surface is exposed to a second reactant fluid, preferably ambient air comprising oxygen. The first and second reactant fluids are substantially fluidly isolated from each other by the membrane when no perforations are present in the membrane. The first reactant fluid contacts the second reactant fluid when at least one perforation is present in the membrane. The first and second reactant fluids exothermically react upon contact, preferably in the presence of a catalyst, to generate heat, which is then detected using an infrared thermal detector or thermal imaging device or a layer of thermally sensitive film positioned in proximity with the membrane.

SUMMARY OF THE INVENTION

In the search for efficient electrocatalytic materials and devices, parameters such as current density, potential, selectivity, and stability have played key roles due to their links to future scale-up costs. These direct indicators, however, treat both small and large cells as a black box system where spatial variations across a catalyst are averaged into a singular measured output.

Furthermore, in general, heat generation within electrochemical systems is poorly studied, and the disambiguation of various heating effects (overpotential, ohmic, gas- diffusion layer resistivity) is useful for improving not only catalyst development, but scale-up of electrochemical systems. In systems comprising gas-diffusion electrodes, heat may especially be generated (by catalytic reactions) at the gas-diffusion electrode (‘GDE’). Catalyst activity may depend on the distribution of catalyst over the surface of a GDE. Moreover, catalyst activity and/or the surface of the GDE may change over time because of external reasons, such as operating conditions. There appears to be a need for determining spatial and temporal electrocatalytic activity across a catalyst's surface. Moreover, there appears to be a need to analyze gas-diffusion electrodes under operational conditions.

Hence, it is an aspect of the invention to provide an alternative method for analyzing a gas-diffusion electrode in an electrochemical cell, which preferably further at least partly obviate(s) one or more of above-described drawbacks. It is a further aspect of the invention to provide an alternative electrochemical cell, which preferably further at least obviate(s) one or more of above-described drawbacks. Additionally or alternatively, the invention (also) provides in aspects an arrangement for evaluating an electrochemical cell which preferably further at least obviate(s) one or more of above-described drawbacks. In yet a further aspect, the invention further provides a high throughput method for analyzing a gas- diffusion electrode in an electrochemical cell, which preferably further at least obviate(s) one or more of above-described drawbacks.

The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

In a first aspect, the invention provides a method for analyzing a gas-diffusion electrode (‘GDE’) in an electrochemical cell (“cell”). The method especially comprises providing the electrochemical cell. Further, the electrochemical cell especially includes (comprises) the gas-diffusion electrode. In furthers specific embodiments, the electrochemical cell is an electrochemical cell with (or having) a gas-diffusion electrode. The gas-diffusion electrode may be (especially a removable or exchangeable) part of the electrochemical cell. Further, especially the method comprises an operating stage. In further embodiments, the method (further) comprises a sensing stage. In specific embodiments, the electrochemical cell comprises a fluid flow chamber. The electrochemical cell may in further embodiments (also) comprise an electrolyte chamber. The gas-diffusion electrode may in embodiments define at least part of a primary wall element. In further embodiments, the fluid flow chamber and the electrolyte chamber share the primary wall element (and are separated thereby). In embodiments, the fluid flow chamber and the electrolyte chamber extend from opposite sides of the primary wall element. The primary wall element may especially separate the fluid flow chamber (a fluid flow chamber volume) from the electrolyte chamber (an electrolyte chamber volume). In further specific embodiments, the fluid flow chamber may comprise a window, especially being at least partly transmissive for infrared radiation. The window is in embodiments especially configured for allowing at least part of infrared radiation generated at (especially radiated or emitted by) the gas-diffusion electrode (especially during operation of the electrochemical cell) to propagate via the window to a location outside (of) (external of) the electrochemical cell. Further, especially, in embodiments the operating stage comprises operating the electrochemical cell. The sensing stage may in embodiments comprise: sensing through the window with an infrared sensor (especially configured at a position external of the electrochemical cell, especially outside the electrochemical cell) infrared radiation (generated at the gas-diffusion electrode and especially radiated) from (or by) the gas-diffusion electrode. The sensing stage may in further embodiments especially comprise: sensing through the window with the infrared sensor a wavelength distribution (of the infrared radiation) over the gas diffusion electrode, especially over a first face of the gas-diffusion electrode. The first face (of the GDE) may further especially be configured facing the widow. The infrared (“IR”) sensor may especially be configured at a position external of the electrochemical cell. The IR sensor may be arranged outside the electrochemical cell, especially remote from the electrochemical cell. The IR sensor may in embodiments be configured radiationally coupled with the gas-diffusion electrode.

Additionally, or alternatively, the invention may provide in an aspect the electrochemical cell (per se) (as defined herein). The electrochemical cell may in embodiments be used in the method of the invention.

With this method and electrochemical cell monitoring of the gas-diffusion electrode during operation of the electrochemical cell is enabled. The gas-diffusion electrode (‘GDE’) may especially comprise a catalyst (at a surface of GDE). With the method and the electrochemical cell quality aspects of the electrochemical cell and especially of the gas- diffusion electrode may be determined. Moreover, changes over time may be identified. The method and/or electrochemical cell further enables studying effects of operating parameters on the efficacy of the desired process. In embodiments, the spatial temperature of a catalyst's surface may be sensed within a 10 mK accuracy. This may provide information about a possible overpotential and activity of the catalyst at a given location. The method may be applied to multiple material surfaces for combinatorial catalyst testing, as well as using a singular material to observe current density distributions across a gas-diffusion layer (of the GDE). The method may result in better understanding of processes taking place in the electrochemical systems. This may further facilitate scaling-up of the electrochemical systems.

Relevant benefits of the present invention include that the method is non- intrusive, has a high resolution and can be used during operation of the electrode. The electrochemical cell may e.g., comprise an electrolyzer for electrolysis of e.g., CO ₂ and a gas- diffusion electrode (of the electrolyzer) may be analyzed during CO ₂ electrolysis. In other embodiments, the electrochemical cell may e.g., comprise a fuel cell, and especially a GDE of the fuel cell may be analyzed during generation of electricity (by oxidation of a fuel in the fuel cell). This method may be applied to determine spatio-temporal activity distribution over the electrode. Based on this distribution, among others a distribution of the catalyst over the electrode, flooding of the electrode and effects of operating conditions and design configurations (of the cell as well as the selected catalyst) may be determined, including e.g., gas evolution at the electrode.

Hence, the invention provides in an embodiment, an electrochemical cell comprising a fluid flow chamber and an electrolyte chamber, wherein the gas-diffusion electrode defines at least part of a primary wall element, wherein (i) the fluid flow chamber and the electrolyte chamber share the primary wall element and (ii) the fluid flow chamber comprises a window configured for allowing at least part of infrared radiation generated at the gas-diffusion electrode (during operation of the electrochemical cell) to propagate via the window to a location external of the electrochemical cell.

The invention may especially provide in embodiments an electrochemical cell including (comprising) (or with) a gas-diffusion electrode, wherein the electrochemical cell (further) comprises a fluid flow chamber, an electrolyte chamber, and a primary wall element, wherein (i) the gas-diffusion electrode defines at least part of the primary wall element, (ii) the fluid flow chamber and the electrolyte chamber share the primary wall element, wherein the electrolyte chamber and the fluid flow chamber and the electrolyte chamber extend from opposite sides of the primary wall element, (iii) the fluid flow chamber comprises a secondary fluid flow chamber wall arranged remote from the primary wall element, (iv) the secondary fluid flow chamber wall comprises a window configured for allowing at least part of infrared radiation generated at the gas-diffusion electrode to propagate via the window to a location outside the electrochemical cell.

Further, the invention provides in an embodiment, a method for analyzing a gas-diffusion electrode in an electrochemical cell, the method comprising: (i) providing the electrochemical cell, (wherein the electrochemical cell comprises a fluid flow chamber and an electrolyte chamber, wherein the gas-diffusion electrode defines at least part of a primary wall element, wherein the fluid flow chamber and the electrolyte chamber share the primary wall element, wherein the fluid flow chamber comprises a window configured for allowing at least part of infrared radiation generated at the gas-diffusion electrode to propagate via the window to a location outside (of) / external of the electrochemical cell); (ii) an operating stage, comprising: operating the electrochemical cell; and (iii) a sensing stage, comprising: sensing through the window with an infrared sensor, especially configured outside the electrochemical cell (also described as “at a position external of the electrochemical cell”), infrared radiation (emitted) from the gas-diffusion electrode.

The invention may in specific embodiments provide the method, comprising (i) providing an electrochemical cell including (comprising) a gas-diffusion electrode, especially the electrochemical cell according to the invention; (ii) an operating stage, comprising: operating the electrochemical cell; and (iii) a sensing stage, comprising: sensing through the window with an infrared sensor configured outside the electrochemical cell infrared radiation from the gas-diffusion electrode.

Hence, an aspect of the invention is monitoring a gas diffusion electrode of an electrochemical cell during operating the electrochemical cell. The method may in embodiments especially be a continuous method.

Herein, the term “cell” may be used referring to the electrochemical cell. The term “electrochemical cell” especially refers to a device capable of generating electrical energy/an electrical current from (one or more) chemical reactions and/or using electrical energy / an electrical current to cause (one or more) chemical reactions. The chemical reaction may especially comprise an oxidation-reduction (or “redox”) reaction. An oxidation- reduction reaction is a type of chemical reaction that involves a transfer of electrons between two species. An oxidation-reduction reaction is essentially any chemical reaction in which the oxidation number of a substance, especially a molecule, atom, or ion, changes by gaining or losing an electron. Redox reactions are especially comprised of two parts, a reduced half and an oxidized half, that occur together. The reduced half gains electrons and the oxidation number decreases, while the oxidized half loses electrons and the oxidation number increases. There is no net change in the number of electrons in a redox reaction. Electrons released in the oxidation half reaction are taken up by another species in the reduction half reaction. Herein, the terms “molecule”, “atom”, and “ion” may also be indicated as a “substance”, “species”, “particle”. Multiple redox reactions may take place simultaneously and/or consecutively. Commonly found electrochemical cells that may generate an electric current are e.g., batteries; these may also be called voltaic cells or galvanic cells. In a battery electrical energy may be derived from spontaneous redox reactions taking place within the cell. If a primary cell (or “unrechargeable cell”) is used, chemical reactions in the battery may continue until the chemicals that generate the power are used up (and the battery stops producing electricity). Alternatively, in a secondary cell (or a “rechargeable battery”), the reaction can be reversed by recharging the battery to regenerate the chemical reactants.

Analogous to these batteries wherein the chemicals to generate the electrical energy are substantially stagnant, a fuel cell may be used to provide electrical energy. A fuel cell is especially an electrochemical cell that may convert chemical energy from a fuel into electricity through an electrochemical reaction of the fuel. The fuel may in embodiments comprise hydrogen molecules that may be oxidized with an oxidizing agent. The oxidizing agent may e.g., comprise oxygen (e.g., in air). Additionally, or alternatively, the fuel may comprise methanol (which may be oxidized). A fuel cell may have many different configurations known to the person skilled in the art.

Basically, the fuel cell (during operations) comprises three main components: an anode (anodic electrode), a cathode (cathodic electrode), and an electrolyte that allows ions to move between the two electrodes. In most configurations/embodiments, a catalyst may cause the fuel to undergo an oxidation reaction at the anode thereby generating ions (such as positively charged hydrogen ions) and electrons and the ions may move towards the cathode. Additionally, or alternatively, ions (especially negatively charged ions) may be generated at the cathode and move to the anode, which in embodiments may react with ions generated at the anode forming new molecules. The term “electrolyte” may in embodiments refer to a fluid, especially an ionic solution. The term may also refer to a solid, such as a cation exchange membrane in Membrane Electrode Assemblies (MEAs). A solid electrolyte may e.g., be configured in (a MEA) of a PEM (Polymer electrolyte membrane) electrolyzer. The term “electrolyte” may especially refer to a plurality of (different) electrolytes.

During operation, the ions may move through the electrolyte from the anode to the cathode (and/or vice versa), while concurrently the generated electrons may flow from the anode to the cathode through an (external) electrically conductive circuit, producing direct current electricity. At the cathode, a further catalyst may cause a substance (e.g., an ion), electrons, and oxygen to react, forming e.g., water and possibly other products. In embodiments, one or more of the anode and the cathode comprises a gas-diffusion electrode separating the electrolyte from a fuel supply at the anode and/or separating an oxidizing agent supply from the electrolyte at the cathode, respectively (while allowing a transport of one or more of the -gaseous- fuel and the -gaseous- oxidizing agent through the respective gas- diffusion electrode to the catalyst (see also below)). To sustain the electrochemical reaction the fuel (e.g., hydrogen) may in embodiments be continuously supplied to the fuel cell (during operating the fuel cell). Also the oxidizing agent, e.g., air (comprising oxygen) may especially be continuously supplied to the fuel cell (during operating the fuel cell). In further embodiments, the electrolyte may be transported/ flown trough the (electrolyte chamber of) the fuel cell. Based on the flow of one or more of the fuel, the oxidizing agent and the electrolyte through the fuel cell, the fuel cell may in embodiments be named a “flow-cell”.

The electrochemical cell, especially the fuel cell, may in embodiments comprise a flow-cell fuel cell.

The electrochemical cell may, depending on the embodiment, comprise a number of different chambers as described herein. Examples of these chambers are the fluid flow chamber, the electrolyte chamber and the second fluid flow chamber (see below). Such chamber may in embodiments comprise two openings. A first opening may be used to provide a fluid or e.g., an electrolyte in the chamber (and may be named “inlet opening” or “feed opening”) and a second opening may be used to allow an exit or discharge of the fluid or electrolyte (respectively) (and may be named “exit opening” or “discharge opening”). In embodiments one or more of the chambers may comprise a single opening. For instance, if a substance (e.g., a gas) is formed, the fluid flow chamber may only require an exit opening to discharge the substance (and no feed opening). Alternatively (also) a feed opening may be present, e.g., for feeding an inert gas. Likewise, if a fluid is consumed during operation, a fluid flow cell may in embodiments only comprise a feed opening to provide the fluid (and no discharge opening). In embodiments, a flow chamber (the fluid flow chamber and/or the second fluid flow chamber) comprises one opening (for providing or discharging a fluid). Further, the electrolyte chamber and/or one or more electrolyte compartments of the electrolyte chamber (see below) may in embodiments comprises at least one opening, and especially two openings to feed and/or discharge a respective electrolyte. Hence, one or more of the fluid flow chamber, the electrolyte chamber, and the second fluid flow chamber (if present) may in embodiments comprise a flow through chamber. Also in embodiments, an electrolyte compartment may comprise a flow-through electrolyte compartment.

A gas-diffusion electrode or “GDE” is an electrode (thus being electrically conductive) that allows gas molecules to pass from one side (or face) of the electrode to another side of the electrode (whereas liquids may especially be blocked). Gas-diffusion electrode(s) may generally extend in two dimensions significantly further than in the third dimension so that a two-dimensional -like object is provided. A GDE may in embodiments comprise a planar GDE. The GDE may further comprise a catalyst (for one or more of the oxidation-reduction half reactions), especially at a surface of the GDE. In embodiments, the catalyst (surface) may be arranged directly contacting the electrolyte. A GDE may further in embodiments be characterized as an electrode with a conjunction of a solid, liquid, and gaseous interface, and an electrical conducting catalyst supporting an electrochemical reaction between the liquid and the gaseous phase. The catalyst (layer) may especially be arranged at (or define) a gas/liquid interface. The GDE may especially have a gas-diffusion layer, especially being permeable for the (predetermined) gaseous molecules. Further, the GDE may have a catalyst layer, especially a porous catalyst layer. The GDE may have a first face configured for contacting the electrolyte and a second (opposite) face (for contacting the fluid). In embodiments, the first face comprises the catalyst (layer). The first face of the GDE may especially be configured facing inwards of the electrolyte chamber (in embodiments wherein the GDE contacts the electrolyte chamber space). The second face of the GDE may be configured facing inwards of a fluid flow chamber (in embodiments wherein the GDE (further) contacts the fluid flow chamber space). Especially fluids described herein may diffuse trough embodiments of gas-diffusion electrodes described herein. The electrochemical cell described herein may especially comprise a GDE comprising a catalyst. The term “electrochemical cell” may especially relate to (a cell of) an electrocatalytic reactor. Further, the electrochemical cell is especially an operating electrochemical cell that may be used for generating electrical energy/an electrical current or for electrolyzing substances (especially based on redox reactions) during operation thereof.

The term “fluid” such as in “fluid”, “fluid flow” and “fluid flow chamber” may relate to a gaseous fluid and a liquid. The term especially relates to a gaseous fluid. In embodiments, the fluid is dissolved in a liquid phase.

The term “gas-diffusion electrode” may further refer to more than one (different) gas-diffusion electrodes. For instance, in embodiments a first gas-diffusion electrode may define at least part of the primary wall element, and especially a further or second gas-diffusion electrode may define at least part of a secondary fluid flow chamber wall (see below). Different gas-diffusion electrodes may in embodiments be permeable for different gasses. In embodiments the electrochemical cell may comprise a primary wall comprising the primary wall element. In further embodiments the GDE defines the entire primary wall element. A part of the primary wall may comprise, or may be, the primary wall element. In embodiments e.g., 10% of a total surface of the primary wall corresponds to the primary wall element. In further embodiments at least 20% of the surface comprises the primary wall element, such as at least 35%, especially at least 50%, or even more, such as substantially 100% in embodiments.

An electrolytic cell or “electrolyzer” or “electrolyser” is especially an electrochemical cell in which one or more (non-spontaneous) redox reactions may be initiated by providing electrical energy to the cell. Commonly, the electrolytic cell is used to decompose and/or to transform chemical species, in a process called electrolysis. The chemical species are especially “electrolyzed” during electrolysis. During electrolysis electrons may be transferred from an electrode to the chemical species (and/or vice versa) to decompose or transform the species.

Well known examples of electrolysis are the decomposition of water into hydrogen and oxygen and the electrolysis of brine for producing hydrogen and chlorine gases. Yet also substances like carbon dioxide, and sulfur dioxide may be electrolyzed (transformed). Carbon dioxide may (especially in the presence of water or hydroxide), e.g., be transformed to ethylene during electrolysis, see further below. Also an electrolyzer may especially have three major component parts: two electrodes (a cathode and an anode) and an electrolyte contacting both electrodes (and functionally or electrolytically (or “ionically”) connecting the anode to the cathode). The electrolyte is usually a solution of water or other solvent in which ions are dissolved or may, e.g., comprise molten salts or rather immobile materials hosting ions that may move in the material (also referred to as “solid phase electrolyte”). When an external voltage difference is applied over the electrodes, the ions in the electrolyte may be attracted to an electrode with the opposite charge, where charge transferring (or redox) reactions can take place.

In recent years, electrolyzers have been introduced for electrochemical carbon dioxide electrolysis, or CCk-reduction. In such process CO2 may be dissolved in an electrolyte and may electrochemically be reduced on a catalyst surface. To circumvent limitations because of a low solubility and a low diffusivity of CO2 in the electrolyte, CO2 may also be introduced in the cell in the gas phase and a transport of CO2 towards the catalyst surface may be provided by using a gas-diffusion electrode (separating the gaseous CO2 from the electrolyte). In embodiments, if the CO2 diffuses through the GDE to the electrolyte, the CO2 may be reduced at the catalyst surface of the GDE and a transport of CO2 from the bulk of the electrolyte to the electrode may not be required (anymore). In embodiments of the method, e.g., a fluid comprising an electrolyze-able substance, e.g., CO ₂ , may be provided to the fluid flow chamber. When contacting the GDE, the electrolyze-able substance may be transported (diffused) through the GDE towards an electrolyte in the electrolyte chamber. When contacting the electrolyte and the GDE (especially the catalyst), the electrolyze-able substance may be electrolyzed (electrochemically reduced). The fluid may in embodiments flow through the fluid flow chamber or be transported through the fluid flow chamber. The method may comprise flowing (or transporting) a fluid through the (respective) fluid flow chamber. In further embodiments the electrolyte may flow through the electrolyte chamber (e.g., to refresh the electrolyte). The electrolyzer may in embodiments (also) be referred to as a flow-cell. The electrolyzer may in embodiments comprise a flow-cell. Moreover, herein the term “providing” in relation to providing a fluid, an electrolyte, etc. to a specific location such as a chamber, may also comprise transporting (the fluid and/or the electrolyte, etc.) through the location (chamber), or flowing (the fluid, etc.) through the location.

The term “electrolyze-able substance” may herein especially refer a molecule, atom, or ion of which the oxidation number may change by (i) accepting an electron from the (negatively charged) electrode (or cathode) or (ii) losing an electron to the (positively charged) electrode (or anode).

A non-limiting list of electrolyze-able substance comprises e.g., carbon dioxide (CO ₂ ), carbon monoxide (CO), oxygen (O ₂ ), nitrogen (N ₂ ), nitric oxide (NO), nitrogen dioxide (NO ₂ ), sulfur dioxide (SO ₂ ), ethylene (C ₂ H ₄ ), hydrogen (EE), and methane (CH ₄ ), water (H ₂ O), and acetonitrile (C ₂ H ₃ N). Especially CO ₂ , CO, O ₂ , N ₂ , NO, NO ₂ , and SO ₂ may be substances that may electrochemically be reduced. Substances that electrochemically be reduced may herein also be indicated “electrochemically reduceable substances”. Further, especially O _2, C ₂ H ₄ , EE, and CEE may be substances that (also) may electrochemically be oxidized (or “electrochemically oxidizable substances”). Further NO, CO ₂ , and C ₂ H ₃ N may be dissolved in water and may electrochemically be reduced. Water may further electrochemically be reduced and oxidized. In further specific embodiments, the electrolyze-able substance comprises one or more substances selected from the group of water (EEO), carbon dioxide (CO ₂ ), carbon monoxide (CO), oxygen (O ₂ ), nitrogen (N ₂ ), nitric oxide (NO), nitrogen dioxide (NO ₂ ) and sulfur dioxide (SO ₂ ).

Hence, in specific embodiments, the substances in the electrolyte may electrochemically be oxidized and/or reduced. Based on the redox reactions also gas (dissolved) molecules may be formed. In such embodiments also a gas-diffusion electrode may be applied, especially to transport the dissolved molecules from the electrolyte to the fluid flow chamber and/or a second fluid flow chamber. In such embodiments, the transported molecules may flow through the fluid flow chamber, especially to an outlet of the fluid flow chamber. Hence, also this may be embodiments of a flow-cell.

The electrochemical cell may in embodiments comprise an electrolyzer. The electrolyzer may in further embodiments comprise a flow-cell electrolyzer. The electrochemical cell may in further embodiments comprise a fuel-cell, especially a flow-cell fuel cell. The term “electrochemical cell” may especially refer to an electrolytic cell or a fuel cell. The terms “electrolytic cell” and “electrolyzer” may be used interchangeably herein.

A specific aspect of the invention is especially the use of infrared thermography for screening electrodes in the electrochemical cell, especially in a GDE flow- cell electrolyzer and/or a GDE flow-cell fuel cell. Using an infrared sensor, heat generated over the electrode may especially be measured through an infrared transmissive window that may be configured in the electrochemical cell (especially the electrolyzer or in a fuel cell). The IR sensor may be configured outside the electrochemical cell. Moreover, the IR sensor may be arranged downstream from the window, relative to heat generated at the electrode. The GDE is therefore especially arranged upstream of the window. The term “infrared sensor” may refer to a plurality of different infrared sensors, or e.g., an array of IR sensors. The infrared sensor may in embodiments comprise an infrared camera. The window may comprise an infrared transmissive material. An unlimited list of examples of IR transmissive materials are e.g., silicon, Germanium, CaF ₂ , KBr, ZnSe, BaF ₂ , and MgF _2. The IR transmissive material may in further embodiments comprise AI ₂ O ₃ , especially sapphire. In further embodiments, the IR transmissive material comprises an IR-translucid polymer. Further, in embodiments the window may comprise quartz, especially fused quartz. In yet further embodiments, the window comprises glass. The window may in embodiments comprise a glassy window with IR transmittance in the mid-IR range (especially having a wavelength of about 3-8 pm).

Heat may be generated at (the gas-diffusion) electrode, especially by the electrochemical reaction (during operation of the electrochemical cell). Based on the generated heat, the electrode may heat up and emit infrared (or “IR”) radiation. In embodiments, the heat may be generated at the first face of the GDE. Based on the generated heat also the second face of the GDE may heat up. Hence, especially (also) the second face (or also indicated as “backside”) of the GDE may emit IR radiation as a result of the electrochemical reaction (at the GDE). The IR radiation may be emitted by (the second face of) the GDE and propagate through the fluid flow chamber. For sensing the IR radiation, the fluid flow chamber may especially be configured having the window in a further, or secondary, fluid flow chamber wall, especially such that an imaginary straight line between at least part of (the second face of) the GDE and a location outside (or external of) the electrochemical cell, especially of the fluid flow chamber, crosses the window. The secondary fluid flow chamber wall is especially arranged remote of the primary wall element. The secondary fluid flow chamber wall and the primary wall element may enclose the fluid flow chamber volume. Moreover, in further embodiments the primary wall and the secondary fluid flow chamber wall may enclose the fluid flow chamber volume. In further embodiments, the secondary fluid flow chamber wall may be configured opposite to the primary wall element. With respect to the (IR) radiation, the window is especially configured downstream from the GDE. In further embodiments, the IR sensor is configured downstream from the window (with respect to IR radiation generated by the GDE).

The terms “upstream” and “downstream” relate to an arrangement of items or features relative to the propagation of the radiation from a radiation generating means (here especially the GDE), wherein relative to a first position within a beam of radiation from the radiation generating means, a second position in the beam of radiation closer to the radiation generating means is “upstream”, and a third position within the beam of radiation further away from the radiation generating means is “downstream”.

In further embodiments, (also) the electrolyte chamber comprises a secondary electrolyte chamber wall. The secondary electrolyte chamber wall is especially arranged remote of the primary wall element. The secondary electrolyte chamber wall and the primary wall element may enclose the electrolyte chamber volume. In further embodiments, the secondary electrolyte chamber may be configured opposite to the primary wall element. As described above, during operation of the electrochemical cell, the electrochemical cell may especially comprise two electrodes and an electrolyte contacting both electrodes. The electrochemical cell may in embodiments comprise the GDE and a second electrode. Especially, the second electrode may define at least part of the secondary electrolyte chamber wall.

Hence, in further embodiments the fluid flow chamber may comprise a secondary fluid flow chamber wall configured opposite to the primary wall element, wherein the secondary fluid flow chamber wall comprises the window, especially wherein the electrolyte chamber further comprises a secondary electrolyte chamber wall configured opposite to the primary wall element, wherein a second electrode defines at least part of the secondary electrolyte chamber wall.

Herein the terms “external of’, “outside of’, “outside” in relation to the electrochemical cell may be used, e.g., in phrases like “at a location external of the electrochemical cell”, or “a location outside (of) the electrochemical cell”. These terms may be mutually exchangeable and especially refer to a position or a location outside the electrochemical cell, such as remote from the cell or in the proximity of the cell (but not in the cell). Moreover, the cell may have a wall defining the cell and an “inside” of the cell. In embodiments (e.g. comprising a single fluid flow chamber and a single electrolyte chamber), the fluid flow chamber and the electrolyte chamber may define the inside of the cell. In further embodiments, e.g., comprising two fluid flow chambers, the two fluid flow chambers and the electrolyte chamber may define the inside of the cell. The gas-diffusion electrode is especially arranged inside the electrochemical cell. Moreover, the window may especially be arranged with a first side facing (and contacting) the inside, and another side facing (and contacting) the outside of the cell.

The window is in embodiments hermetically sealed in the secondary fluid flow chamber wall. In further embodiments a gasket is arranged around the window for hermetically sealing the window in the secondary fluid flow chamber wall. The gasket may comprise any arbitrary material that may hermetically seal. In embodiments, the gasket comprises silicone.

In embodiments, the electrochemical cell essentially contains two chambers: a fluid flow chamber and an electrolyte chamber. Moreover, in embodiments the electrolyzer may contain the two chambers. In further embodiments, the electrolyte chamber may comprise two compartments. The electrochemical cell may in embodiments comprise an ion exchange membrane (“membrane”) configured for (physically) diving the electrolyte chamber in a first electrolyte compartment and a second electrolyte compartment. The first electrolyte compartment may in embodiments be defined by the ion exchange membrane and one of the primary wall element and the secondary electrolyte chamber wall. The second electrolyte compartment may then be defined by the ion exchange membrane and the other one of the primary wall element and the secondary electrolyte chamber wall.

Hence, in embodiments, the first electrolyte compartment may comprise the primary wall element and the second electrolyte compartment may comprise the secondary electrolyte chamber wall. Further, in some of these embodiments, the primary wall element may comprise the cathode and the secondary electrolyte chamber wall may comprise the anode. Therefore, in such embodiments, a first electrolyte in the first electrolyte compartment may also be named a catholyte, and a further or second electrolyte in the second electrolyte chamber may also be named an anolyte. Likewise, the first electrolyte compartment may be named a catholyte compartment, and the second electrolyte compartment may be named anolyte compartment. It will be understood that other configurations are also possible, e.g., wherein the compartments are switched or wherein the anode and cathode are swapped. In such embodiments, the first electrolyte may be named catholyte and the second electrolyte may be called anolyte, and the compartments may be named catholyte compartment and anolyte compartment for the first electrolyte compartment and the second electrolyte compartment, respectively. In further embodiments the (first) gas-diffusion electrode is configured for contacting the first electrolyte, and the second electrode is configured for contacting the second electrode.

Especially, in specific embodiments (especially wherein the electrochemical cell comprises an electrolyzer), the electrochemical cell comprises an ion exchange membrane configured for (physically) diving the electrolyte chamber in a first electrolyte compartment comprising the primary wall element and a second electrolyte compartment comprising the secondary electrolyte chamber wall. The ion exchange membrane is especially configured for allowing a transfer of positively or negatively charged ions. Depending on the application, the ion exchange membrane may comprise a cation exchange membrane or an anion exchange membrane. For instance, if protons are formed (such as based on a cathodic reaction during water splitting) the ion exchange membrane may comprise a cation exchange membrane allowing a transport of protons. In further embodiments, e.g., configured for a basic/alkaline medium reaction (such as alkaline water splitting), the ion exchange membrane may comprise an anion exchange membrane. The type of ion exchange membrane may especially be selected depending on a need for a transport of anions or for a transport of cations.

With an electrochemical cell comprising the ion exchange membrane, the operating stage of the method may in further embodiments comprise: providing a first electrolyte (especially a catholyte) to the first electrolyte compartment and providing a second electrolyte (especially an anolyte) to the second electrolyte compartment, especially wherein the first electrolyte and the second electrolyte together provide an ionic contact between the gas-diffusion electrode and the second electrode (especially via the ion exchange membrane). In further embodiments, the operating stage comprises providing a fluid to the fluid flow chamber, wherein the fluid comprises an electrolyze-able substance. The operating stage may especially comprise flowing the fluid through the fluid flow chamber.

Additionally, or alternatively, the operating stage may comprise providing an electrolyte comprising an electrolyze-able substance to one or more of the first electrolyte compartment and the second electrolyte compartment, especially to the first electrolyte compartment. Further, the operating stage may especially comprise imposing an electric potential difference between the gas-diffusion electrode and the second electrode to electrolyze the electrolyze- able substance at the gas-diffusion electrode.

Herein the terms like “ionic contact”, “ionic connection” such as in the phrases like the first element is in ionic contact with a second element, or “the electrolyte provides an ionic contact between the gas-diffusion electrode and the second electrode”, especially refer to the fact that ions may move from the first element to the second element and vice versa (especially positive ions to a negative electrode and negative ions to a positive electrode).

The terms “ionic connection/contact” and the “electrolytical connection/contact” may be used interchangeably.

In embodiments the first electrolyte compartment and the second electrolyte compartment may have a substantially equal volume. Yet, a ratio of these volumes may have any arbitrary value. In embodiments a smallest distance between the ion exchange membrane and one or more of the gas-diffusion electrode and the second electrode may be in the range of 0.1-10 cm, such as in the range of 0.1-5 cm. In embodiments the smallest distance may be 1-5 mm, especially 1-2 mm. In other embodiments the smallest distance may be 2.5-30 mm, such as 5-20 mm. For instance, a smallest distance between the gas-diffusion electrode and the second electrode (arranged parallel to the GDE) may in embodiments be about 2 mm, wherein the smallest distance between the membrane and the GDE is about I mm. In other examples the smallest distance between the gas-diffusion electrode and the second electrode (arranged parallel to the GDE) may be about 5 cm or about 2 cm, and the smallest distance between the membrane and the GDE is about 2.5 or 1 cm respectively.

In further specific embodiments, the ion exchange membrane may be configured adjacent (proximate) to (including contacting) the first electrode or to the second electrode, especially to the gas-diffusion electrode. A smallest distance between the gas- diffusion electrode may e.g., be in the micrometer range such as 3000 pm at maximum, e.g., in the range of 0-1000 pm, especially equal to or less than 500 pm, such as equal to or less than 100 pm, especially equal to or less than 10 pm, such as substantially zero. The ion exchange membrane may in embodiments be configured at (and contacting) the gas-diffusion electrode. In embodiments, the gas-diffusion electrode comprises the ion exchange membrane. The ion exchange membrane may e.g., be arranged covering the catalyst (layer). The GDE may in specific embodiments comprise a (membrane electrode) assembly comprising the catalyst (layer) and membrane. In embodiments the catalyst (layer) and the membrane may be hot-pressed together. In such embodiment, the first electrolyte may substantially be stagnant. The first electrolyte may substantially (only) be present in pores of the gas-diffusion electrode and/or in spaces between the ion exchange membrane and the catalyst layer and/or the gas-diffusion electrode. The first electrolyte may further be in the membrane. The membrane is especially hygroscopic.

Hence, in further embodiments, the electrochemical cell (especially comprising an electrolyzer) comprises an ion exchange membrane configured adjacent to the gas-diffusion electrode in the electrolyte chamber, especially wherein a (smallest) distance between the gas-diffusion electrode and the ion exchange membrane is selected in the range of 0-1000 pm. In further embodiments the gas-diffusion electrode comprises an ion exchange membrane layer configured at the first face of the gas-diffusion electrode facing the secondary electrolyte chamber wall. Especially, using such embodiments in the method of the invention, the operating stage may in embodiments comprise (i) providing an electrolyte, especially an anolyte, to the electrolyte chamber, wherein the electrolyte provides an ionic contact between the gas-diffusion electrode and the second electrode (especially via the ion exchange membrane, (ii) providing a fluid to the fluid flow chamber (especially transporting the fluid through the fluid flow chamber), wherein the fluid comprises an electrolyze-able substance; and (iii) imposing the electric potential difference (V) between the gas-diffusion electrode and the second electrode to electrolyze the electrolyze-able substance at the gas- diffusion electrode.

The electrolyze-able substance may especially comprise one or more of the electrolyze-able substances described above. In specific embodiments, the electrolyze-able substance comprises CO2. The electrolyte may in embodiments comprise an aqueous electrolyte. The electrolyte may further comprise any kind of arbitrary ions. In embodiments, the electrolyte may comprise one or more of KOH, NaOH, Li OH, CsOH, and a bicarbonate. The bicarbonate may e.g., comprise KHCO3 and/or NaHC03. The ions may e.g., be in embodiments selected from K ⁺ , Na ⁺ , Li ⁺ , Cs ⁺ , OH, and HCO3 . In the method, CO2 may in embodiments be reduced (at the gas-diffusion electrode) to e.g., CO, C2H4, C¾, depending on the catalyst of the GDE. Concurrently, hydroxide ions may be oxidized at the second electrode, wherein oxygen may be provided. Herein, the method may especially be explained referring to CO2 as an example of an electrolyze-able substance that may electrochemically be reduced (at a cathodic gas-diffusion electrode). Yet, also other electrolyze-able substance that may electrochemically be reduced, such as the ones described herein may be used in embodiments of the method.

Alternatively, the gas-diffusion electrode may comprise the anode, and e.g., the electrolyze-able substance comprises one or more of the electrolyze-able substances described above in relation to substances that may be electrochemically oxidized

As further discussed above, in further embodiments, the electrolyte (or the first electrolyte and/or second electrolyte) may comprise the electrolyze-able substance, such as water, acetonitrile, or one or more of the gaseous electrolyze-able substances described herein being dissolved in the electrolyte. In such embodiments, the operating stage may in embodiments comprise (i) providing the electrolyte comprising an electrolyze-able substance to the electrolyte chamber (wherein the electrolyte provides an ionic contact between the gas- diffusion electrode and the second electrode (especially via the ion exchange membrane)) and (ii) imposing an electric potential difference (V) between the gas-diffusion electrode and the second electrode to electrolyze the electrolyze-able substance at the gas-diffusion electrode (15), and optionally (iii) flowing (especially discharging) a fluid through (or from) the fluid flow chamber, wherein the fluid comprises an a (gaseous) formed at the gas-diffusion electrode (as a result of the redox reaction).

As described above, the fluid flow chamber and the electrolyte chamber may share the primary wall element, and especially are separated thereby. Herein a wall or wall element that is shared by chambers or volumes may essentially separate these two chambers or two volumes. A shared wall or wall element may form a mechanical barrier. For instance, water as example to define the wall, may essentially not penetrate from the one chamber to the other chamber via the wall element.

In yet further embodiments, the electrochemical cell may further comprise a second fluid flow chamber. Also the second fluid flow chamber may be functionally coupled to the electrolyte chamber via a gas-diffusion electrode. Especially, the second electrode may comprise a (second) gas-diffusion electrode. The second fluid flow chamber and the electrolyte chamber may especially share the secondary electrolyte chamber wall (extending from opposite sides of the wall). Such embodiment may for instance be used in embodiments of the method wherein a second fluid is provided to the second fluid flow chamber, especially wherein the second fluid (also) comprises a (further) electrolyze-able substance, and that especially may be transported through the gas-diffusion electrode towards the electrolyte chamber. Yet additionally or alternatively, a gaseous substance may be formed at the second gas-diffusion electrode and may diffuse through the second gas-diffusion electrode to the fluid flow chamber. The second gas-diffusion electrode may in embodiments be configured as is described above in relation to the gas-diffusion electrode. The second gas-electrode may (also) have a first face and a second face, especially wherein the second face is configured closer to the (first) gas-diffusion electrode than the first face. Moreover, in embodiments the second face of the gas-diffusion electrode and the second face of the second gas-diffusion electrode may be arranged for contacting the electrolyte. In embodiments, the ion exchange membrane is configured in the electrolyte chamber and especially the (first) gas-diffusion electrode and the second gas-diffusion electrode may be configured at opposite sides of the ion exchange membrane.

Hence, in further embodiments, the electrochemical cell further comprises a second fluid flow chamber, wherein the second fluid flow chamber and the electrolyte chamber share the secondary electrolyte chamber wall, and especially wherein the second electrode comprises (especially is) a second gas-diffusion electrode. Moreover, in further embodiments, the second fluid flow chamber may also comprise a second window (wherein the second window is) configured for allowing at least part of infrared radiation generated at the second electrode to propagate via the second window to a location outside (or external of) the electrochemical cell. The second window and the (first) window may in embodiments be configured substantially the same.

As describe above, the electrochemical cell comprising a second fluid flow chamber (in addition to the (first) fluid flow chamber) may be used as an electrolyzer, especially may comprise an electrolyzer. Yet in further embodiments such electrochemical cell comprising the second fluid flow chamber may be used as a fuel cell, especially may comprise a fuel cell.

In further embodiments, especially wherein the electrochemical cell comprises a fuel cell, the operating stage may comprise (i) providing an electrolyte in the electrolyte chamber, wherein the electrolyte provides an ionic contact between the gas-diffusion electrode and the second electrode (ii) providing a fluid to the fluid flow chamber, wherein the fluid comprises a (electrochemically) reducing substance; providing a second fluid to the second fluid chamber, wherein the second fluid comprises an (electrochemically) oxidizing substance; and (iii) oxidizing the reducing substance at the gas-diffusion electrode and reducing the oxidizing substance at the second electrode, thereby generating an electric potential difference (V) between the gas-diffusion electrode and the second electrode.

The term “oxidizing substance” may relate to an oxidizing agent. The oxidizing substance may be electrochemically reduced and may also be referred to as an electrochemically reduceable substance. The term “reducing substance” may relate to a reducing agent. The reducing agent may be electrochemically oxidized and may also be referred to as an electrochemically oxidizable substance. The oxidizing substance may e.g., comprise oxygen (gas). The reducing substance may in embodiments be hydrogen, methanol or a combination of hydrogen and methanol.

In embodiments, the fluid comprises hydrogen (gas). In further embodiments the fluid comprises (gaseous) methanol. In further specific embodiments fluid comprises one or more of hydrogen gas and methanol. The second fluid may especially comprise oxygen gas. The second fluid may, e.g., be or may comprise air.

The electrolyte may in embodiments comprise an alkaline electrolyte, especially comprising hydroxide ions. In further embodiments, the electrolyte may comprise an acidic electrolyte. The electrolyte may e.g., comprise phosphorus acid. The electrolyte may in further specific embodiments comprise a solid phase electrolyte, especially hosting ions that may move in the solid phase material. In yet further embodiments, the electrolyte comprises a molten salt, especially a molten carbonate salt. In further embodiments, the electrolyte comprises (i) an alkaline electrolyte, (ii) an acidic electrolyte, (iii) a solid phase electrolyte, or (iv) a molten carbonate salt.

The method may in embodiments comprise using (applying) an electrical current (or electrical energy) to electrolyze one or more substances. In further embodiments, the method may comprise fueling (oxidizing) a substance to provide (produce) an electrical current (or electrical energy). The system (electrochemical cell) and method used for electrolyzing and for producing electrical energy are comparable. Overall, the operating stage may especially comprise (i) providing an electrolyte in the electrolyte chamber (especially flowing or transporting the electrolyte through the electrolyte chamber,) (wherein the electrolyte provides an ionic contact between the gas-diffusion electrode and the second electrode), (ii) providing a fluid to the fluid flow chamber (especially transporting the fluid through the fluid flow chamber) and optionally providing a second fluid to the second fluid chamber (when present) (especially transporting the second fluid through the second fluid flow chamber); and (iii) generating an electric potential difference (V) between the gas- diffusion electrode and the second electrode. It may be understood that the phrase “generating an electric potential difference between the gas diffusion electrode and the second electrode” may refer to imposing (from external) the electric potential difference over the electrodes to electrolyze (one or more substances). The phrase may also refer to oxidizing a fuel in the fuel cell and thereby producing an electrical current and generating the potential difference.

Hence, in further embodiments, the electrochemical cell (especially comprising an electrolyzer) further comprises a voltage source functionally connected to the gas-diffusion electrode and the second electrode for imposing an electric potential difference between (or “over”) the gas-diffusion electrode and the second electrode.

In further embodiments the electrochemical cell (especially comprising a fuel cell) further comprises one or more of a battery and an energy consuming system functionally connected to the gas diffusion electrode and the second electrode and configured for storing and/or consuming energy provided by the electrochemical cell during operation.

In further embodiments, the method further comprises an analyzing stage. The analyzing stage may especially comprise determining a temperature distribution over at least part of the gas-diffusion electrode, especially the first face of the gas-diffusion electrode based on the sensed infrared radiation. The sensed IR radiation may comprise information about a distribution of the wavelength of the (IR) radiation over at least part of (the surface of) the GDE. Based on this distribution a local temperature at a specific position of the GDE may be determined. During operations a spatio-temporal temperature distribution may be determined in the analyzing stage.

The method may especially be used to analyze or detect defects in the gas diffusion electrode, or defects or changes that emerge during operation of the electrochemical cell, such as operational deterioration of the gas-diffusion layer and catalyst layers. The method may comprise studying effects of a configuration of the electrochemical cell. Some further examples to use the method are for instance scale-up analysis, combinatorial catalyst research, research on hotspot formation and/or salt formation, studies on the effects of stacking multiple electrochemical cells, studies on the effects of a type of catalyst, studies on effects of the type of GDE. Hence, the method may comprise scale-up analysis, combinatorial catalyst research, research on hotspot formation and/or salt formation, studies on the effects of stacking multiple electrochemical cells. In further advantageous embodiments one or more of the gas-diffusion electrodes are detachable. Moreover, in specific embodiments the primary wall element is detachable. The primary wall element may especially be removable. Optionally (also) the second electrode is detachable. Such detachable element allows replacing the element with a further element, e.g., to study the effect of the configuration of the element. For instance, an initial GDE may be replaced by a further GDE, wherein the type of catalyst may be selected to be different between an initial GDE and a further GDE. Hence, the operating stage may comprise changing a configuration of the electrochemical cell (such as changing the primary wall element).

In specific embodiments, the method comprises determining a defect of the gas-diffusion electrode, wherein the defect comprises one or more of an (unwanted) heterogeneous distribution of a catalyst configured at (the second face of) the gas-diffusion electrode, (local) flooding of the gas-diffusion electrode, a chemical or physical deterioration of the ion exchange membrane adjacent to the gas diffusion electrode, an operational deterioration of the gas diffusion electrode, especially the gas diffusion layer and/or the catalyst layer.

The term “flooding” in phrases like “flooding of the (gas-diffusion) electrode” especially refers to (local) penetration of the primary fluid chamber by electrolyte. Especially small defects may lead to a non-confinement of the electrolyte, such that the electrolyte may move from the second face to the first face of the GDE.

The operating stage may in further embodiments comprise adjusting an operating parameter during operating the electrochemical cell. The analyzing stage may then especially comprise determining an effect of the operating parameter on the temperature distribution over at least part of the gas-diffusion electrode. The term “operating parameter” may especially refer to a plurality of different operating parameters.

In embodiments, the operating parameter comprises an imposed electric potential difference imposed between the gas-diffusion electrode and the second electrode. In a further embodiment, the operating parameter comprises a pressure in the fluid flow chamber. Additionally, or alternatively, the operating parameter comprises a composition of the fluid, and/or a flow of the fluid provided to the fluid flow chamber. The operating parameter may further comprise a pressure of the second fluid in the second fluid flow chamber. In further embodiments, the operating parameter comprises a composition of the second fluid in the second fluid flow chamber and/or a flow of the second fluid to the second fluid flow chamber. In specific embodiments, the operating parameter comprises a concentration of the electrolyze-able substance in the fluid flow chamber and/or a composition of the electrolyte in the electrolyte chamber. The operating parameter may further comprise a composition of the first electrolyte in the first electrolyte compartment and/or a composition of the second electrolyte in the second electrolyte compartment. Further operating parameters that may be studied are e.g., a temperature of the fluid in the fluid flow chamber, a temperature of the second fluid in the second fluid flow chamber, and a temperature of the electrolyte in the electrolyte chamber.

In further embodiments, the operating parameter comprises one or more parameters selected from the group consisting of an imposed electric potential difference imposed between the gas-diffusion electrode and the second electrode, a pressure in the fluid flow chamber, a composition of the fluid, a flow of the fluid provided to the fluid flow chamber, a pressure of the second fluid in the second fluid flow chamber, a composition of the second fluid in the second fluid flow chamber, a flow of the second fluid to the second fluid flow chamber a concentration of the electrolyze-able substance in the fluid flow chamber, a composition of the electrolyte in the electrolyte chamber, a composition of the first electrolyte in the first electrolyte compartment, and a composition of the second electrolyte in the second electrolyte compartment, a temperature of the fluid in the fluid flow chamber, a temperature of the second fluid in the second fluid flow chamber, a temperature of the electrolyte in the electrolyte chamber.

In a further aspect, the invention may further provide an arrangement for evaluating an electrochemical cell. The arrangement may especially comprise one or more electrochemical cells described herein. The arrangement may further comprise an infrared analyzing system and especially a control system. In further specific embodiments, the infrared analyzing system comprises at least one infrared sensor (being) configured outside the one or more electrochemical cells (especially at a position external of (remote from) the one or more electrochemical cells) for sensing through the windows of the one or more electrochemical cells infrared radiation from the respective gas-diffusion electrode. In further specific embodiments, the arrangement comprises one or more infrared sensors each infrared sensor being configured outside (at a position external of) a respective electrochemical cell for sensing through its window infrared radiation from the gas-diffusion electrode. Further, especially the control system is in embodiments configured for one or more of (i) analyzing a sensor signal provided by the one or more sensor and (ii) controlling an operation of the one or more electrochemical cells. The control system may especially be configured for controlling one or more operating parameters as described herein.

The invention further provides in an aspect a high throughput method for analyzing a gas-diffusion electrode in an electrochemical cell. The high throughput method especially comprising: (i) providing an arrangement described herein, wherein the arrangement comprises a plurality of electrochemical cells, (ii) simultaneously operating at least a subset of the plurality of electrochemical cells, wherein operating parameters for each of the operated electrochemical cells are individually controlled, and (iii) for each of the operated electrochemical cell: (iiia) sensing through its window infrared radiation from the gas-diffusion electrode, (iiib) determining a temperature distribution over at least part of (a first face of) the gas-diffusion electrode based on the sensed infrared radiation; and (iiic) determining an effect of the operating parameters on the temperature distribution over at least part of the gas-diffusion electrode.

A single infrared sensor may in embodiments be radiationally coupled with the (respective) gas-diffusion electrode of one of the electrochemical cells of the plurality of electrochemical cells. A first infrared sensor may e.g., be radiationally coupled to a GDE of a first electrochemical cell. A second infrared sensor may be radiationally coupled to a GDE of a second electrochemical cell. A third infrared sensor may be radiationally coupled to a GDE of a third electrochemical cell, etc., etc. The term “plurality” such as in a plurality of electrochemical cells especially refers to at least 2. In embodiments, the arrangement may e.g., comprise at least 4 electrochemical cells, such as at least 6, or 12, or 28 or even more than 100. Hence, in embodiments (also) 4, or 6, or 12, or 28, or even more than 100 infrared sensors may be used. In further embodiments a single IR sensor is radiationally coupled to at least the (respective) gas-diffusion electrode of a subset of the electrochemical cells of the arrangement. In embodiments, a single IR sensor may be radiationally coupled to substantially all the electrochemical cells.

The term "radiationally coupled" especially means that the GDE and the IR sensor are associated with each other so that at least part of the radiation emitted by the GDE is received by the IR sensor. In analogy, these conditions may apply when a second gas- diffusion electrode (and second window) is applied (see above). The terms “infrared (“IR”) radiation” or “infrared emission” or “infrared light” especially relates to radiation having a wavelength between 700 nm, especially 780 nm, and 1 mm.

The embodiments described herein in relation to the system of the present invention, may also apply for the method and use of the invention.

The term “controlling” and similar terms herein especially refer at least to determining the behavior or supervising the running of an element, e.g., adjusting a fluid flow or adjusting an imposed potential. Hence, herein “controlling” and similar terms may e.g., refer to imposing behavior to the (controllable) element (determining the behavior or supervising the running of an element), etc., such as e.g., measuring, displaying, actuating, opening, shifting, changing temperature, etc., especially actuating. Beyond that, the term “controlling” and similar terms may additionally include monitoring. Hence, the term “controlling” and similar terms may include imposing behavior on an element and also imposing behavior on an element and monitoring the element. The controlling of the element can be done with the control system. The control system and the (controllable) element may thus at least temporarily, or permanently, functionally be coupled. The element may comprise at least part of the control system. In embodiments, the control system and element may not be physically coupled. Control can be done via wired and/or wireless control. The term “control system” may also refer to a plurality of different control systems, which especially are functionally coupled, and of which e.g., one control system may be a master control system and one or more others may be slave control systems.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which Fig. 1 schematically depicts an embodiment of the electrochemical cell; Fig. 2 schematically depicts aspects of an arrangement of the invention; and Figs 3-4 depict some further aspects of the invention. The schematic drawings are not necessarily to scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 1 schematically depicts an embodiment of the electrochemical cell 1. The figure further depicts an embodiment of the method for analyzing a gas-diffusion electrode 15 in an electrochemical cell 1.

The electrochemical cell 1 comprises a fluid flow chamber 10 and an electrolyte chamber 20, together sharing the primary wall element 18. Moreover, the fluid flow chamber 10 and the electrolyte chamber 20 extend from opposite sides of the primary wall element 18. Further, the primary wall element 18 comprises the gas-diffusion electrode 15 (of the electrochemical cell 1). The gas-diffusion electrode 15 (GDE 15) especially defines at least part of a primary wall element 18. The fluid flow chamber 10 comprises a window 17. In the embodiment, the secondary fluid flow chamber wall 19 comprises the window 17. The secondary fluid flow chamber wall 19 of the fluid flow chamber 10 is configured opposite to the primary wall element 18. The window 17 is at least partly transmissive for infrared radiation 51 and is configured for allowing at least part of infrared radiation 51 generated at the gas-diffusion electrode 15 during operating the electrochemical cell 1 to propagate via the window 17 to a location external of the electrochemical cell 1. The infrared radiation 51 may at least partly propagate from the inside of the electrochemical cell 1 to the outside of the electrochemical cell 1 via the window 17. In the figure, the GDE 15 is configured upstream of the window 17 and the infrared sensor 50 is configured downstream of the window 17. A gasket 13 is arranged around the window 17 for hermetically sealing the window 17 in the secondary fluid flow chamber wall 19. The embodiment further comprises the second electrode 25 which defines part of the secondary electrolyte chamber wall 28.

During the method, the electrochemical cell 1 is operated in an operating stage and IR radiation 51 from the gas-diffusion electrode 15 is sensed through the window 17 with the infrared sensor 50 in the sensing stage, as is indicated by the dotted lines between the sensor 50 and the GDE 15. During operation heat may be generated at the second face 16 of the GDE. The sensor 50 may sense the IR radiation 51 emitted from the first face 14 of the GDE 15. In the embodiment, the IR sensor 50 comprises an IR camera 53.

The operating stage especially comprises (see also Figs 3-4) providing an electrolyte 21 in the electrolyte chamber 20 such that the electrolyte 21 may provide an ionic or electrolytic contact between the gas-diffusion electrode 15 and the second electrode 25; providing a fluid 8 to the fluid flow chamber 10 and optionally proving a second fluid 9 to the second fluid chamber 30 (a second fluid chamber 30 may be present in different embodiments based on Fig. 1 and Figs 3, but is only depicted in the embodiment of Fig. 4); generating an electric potential difference (V) between the gas-diffusion electrode 15 and the second electrode 25. Generating the electric potential may be either directly by imposing the potential over the electrodes 15, 25 for an electrolyzer 3 or may be provided by oxidizing fuel in the fuel cell 4.

Figs 3A-3B depict some aspects of (using) an electrolyzer 3. In the embodiments, the electrochemical cell 1 comprises an ion exchange membrane 24. The membrane 24 splits the electrolyte chamber 20 in a first electrolyte compartment 20a and a second electrolyte compartment 20. b The first electrolyte compartment 20a comprises the primary wall element 18. The second electrolyte compartment 20b comprises the secondary electrolyte chamber wall 25. In the embodiment of Fig. 3B the membrane 24 is arranged closely to the GDE 15 at a minimal distance d that may be in the micrometer range or may even be substantially zero. In further embodiments the GDE 15 comprises the membrane 24.

For operating the embodiments, the operating stage may comprise: providing a first electrolyte, especially a catholyte, 22 to the first electrolyte compartment 20a and a second electrolyte (an anolyte) 23 to the second electrolyte compartment 20b; providing the fluid 8 comprising an electrolyze-able substance such as CO2 to the fluid flow chamber 10; and imposing an electric potential difference (V) between the gas-diffusion electrode 15 and the second electrode 25 (to electrolyze the electrolyze-able substance at the gas-diffusion electrode 15).

During the method, the first electrolyte 22 and the second electrolyte 23 together provide an ionic contact between the gas-diffusion electrode 15 and the second electrode 25, especially via the ion exchange membrane 24.

In the embodiment of Fig. 3B the exchange membrane 24 configured adjacent to the gas-diffusion electrode 15 (at only a small distance d). Therefore, no first electrolyte 22 has to be fed to the electrolyte chamber 20, yet some stagnant first electrolyte 22 will be present between the GDE 15 and the membrane 24. Therefore, for such embodiment the operating stage may especially comprise: providing the electrolyte 21 to the electrolyte chamber 20; providing the fluid 8 comprising an electrolyze-able substance to the fluid flow chamber 10; and imposing the electric potential difference (V) between the gas-diffusion electrode 15 and the second electrode 25 (to electrolyze the electrolyze-able substance at the gas-diffusion electrode 15). Here, especially the electrolyte 21 provides the ionic contact between the gas-diffusion electrode 15 and the second electrode 25 via the ion exchange membrane 24.

In the electrochemical cell 1 depicted in Figs 3 A-3B also the voltage source 60 is depicted that is functionally connected to the gas-diffusion electrode 15 and the second electrode 25 for imposing an electric potential difference (V) between the gas-diffusion electrode 15 and the second electrode 25.

In the depicted embodiments, the respective fluid 8, electrolyte 21, first electrolyte 22, and second electrolyte 23 may be introduced in the electrochemical cell 1 from one side, as indicated by the arrows. Yet, in further embodiments one or more of the fluid 8, electrolyte 31, first electrolyte 22, and second electrolyte 23 may be stagnant or may be fed from another side of the electrochemical cell 1. Especially, if one or more of the fluid 8 and electrolytes 21, 22, 23 is flown through its respective chamber/compartment, the electrochemical cell 1 may in embodiments (also) be referred to as a flow-cell.

The electrolyze-able substance may comprise many different substances known to the skilled person and may for instance comprise one or more substances that may be chemically reduced selected from the group of carbon dioxide (CO2), carbon monoxide (CO), oxygen (O2), nitrogen (N2), nitric oxide (NO), nitrogen dioxide (NO2) and sulfur dioxide (SO ₂ ) and/or one or more substances that may be chemically oxidized selected from the group of oxygen (O ₂ ), ethylene (C ₂ H ₄ ), hydrogen (¾), and methane (CH ₄ ).

Fig. 4 schematically depicts an embodiment of the electrochemical cell 1 comprising two fluid flow chambers 10, 30. The embodiment in Fig. 4 especially depicts a fuel cell 4. More specifically, the embodiment further comprises a second fluid flow chamber 30. In the embodiment, the second fluid flow chamber 30 and the electrolyte chamber 20 share the secondary electrolyte chamber wall 28. Further, the second electrode 25 comprises (or is) a second gas-diffusion electrode. In the depicted embodiment the second fluid flow chamber 30 also comprises a (second) window 17' configured for allowing at least part of infrared radiation 5G generated at the second electrode 25 to propagate via the second window 17' to a location outside (or external of) the electrochemical cell 1.

In the electrochemical cell 1 depicted in Fig. 4 further (very schematically) a battery 61 and/or energy consuming system 62 is depicted which is functionally connected to the gas diffusion electrode 15 and the second electrode 25, and for storing and/or consuming energy provided by the electrochemical cell 1 during operation.

Also an electrolyzer 3 may comprise both fluid flow chambers 10,30. Further embodiments of the electrolyzer 3, may also comprise a membrane 24 (and optionally the two compartments 20a, 20b) depicted in Figs 3A-3B.

For operating the fuel cell 4, the operating stage (of the method) especially comprises providing an electrolyte 21 in the electrolyte chamber 20; providing a fluid 8 comprising a reducing substance such as hydrogen gas and/or (gaseous) methanol to the fluid flow chamber 10; providing a second fluid 9 comprising an oxidizing substance (e.g. air comprising oxygen) to the second fluid chamber 30; and oxidizing the reducing substance element at the gas-diffusion electrode 15 and reducing the oxidizing substance at the second electrode 25. This way an electric potential difference (V) is generating between the gas- diffusion electrode 15 and the second electrode 25. During operation, especially the electrolyte 21 provides an ionic contact between the gas-diffusion electrode 15 and the second electrode 25.

The electrolyte 21 is especially selected to allow ions to be transported (in the electrolyte) and may comprise of conductive fluids e.g., alkaline electrolyte or phosphoric acid. The electrolyte 21 may further comprise a solid phase electrolyte, or a molten carbonate salt.

The method is especially a continuous method, allowing to monitor the electrochemical cell 1. The operating stage may therefore further comprise adjusting one or more operating parameters during operating the electrochemical cell 1 or, e.g., changing a configuration of the electrochemical cell 1. For instance, in embodiments, the primary wall element 18 is detachable and may be changed, e.g., to study different catalyst 12 configured at (different GDE’s 15 of) different primary wall elements 18. Further the method may comprise an analyzing stage, comprising determining a temperature distribution over at least part of the gas-diffusion electrode 15 based on the sensed infrared radiation 51. The temperature distribution may be determined especially over the first face 14 of the GDE 15.

An unlimited list of examples of operating parameter that may be changed comprises e.g. the imposed electric potential difference (V) imposed between the gas- diffusion electrode 15 and the second electrode 25, a pressure PI, a composition, or a flow of the fluid 9, and/or a (fluid) flow of the fluid 9 provided to the fluid flow chamber 10, a pressure P2, a composition and/or a (fluid) flow of the second fluid 9 provided to the second fluid flow chamber 30, a concentration of the electrolyze-able substance in the fluid flow chamber 10, a composition of the electrolyte 21 in the electrolyte chamber 20, a composition of the first electrolyte 22 in the first electrolyte compartment 20a, a composition of the second electrolyte 23 in the second electrolyte compartment 20b, a temperature of the fluid 8 in the fluid flow chamber 10, a temperature of the second fluid 9 in the second fluid flow chamber 20, a temperature of the electrolyte 21 in the electrolyte chamber 20.

The effect of the operating parameter on the temperature distribution over at least part of the gas-diffusion electrode 15 may be determined in the analyzing stage.

The method may especially comprise determining a defect of the gas-diffusion electrode 15, e.g. one or more of an (unwanted) heterogeneous distribution of a catalyst 12 configured at (especially the second face 16 of) the gas-diffusion electrode 15, (local) flooding of the electrode 15, a chemical or physical deterioration of the membrane 24 adjacent to the gas diffusion electrode 15, an operational deterioration of the gas diffusion electrodel5, especially of the gas diffusion layer 11 and/or the catalyst layer 12.

Experimentally it is demonstrated that with the method of the invention a vast temperature difference between a Pt and Ag catalyst for water-splitting could be measured. Also the effects of CO2 dissolution on the temperature rise during CO2 electrolysis in an alkaline environment could be clearly identified. The observations provide a means of detecting premature gas-diffusion layer flooding, salt formation on the GDE, especially on the gas-diffusion layer, spatial variations, temperatures for reaction-diffusion modelling systems and flow imbalances. The (thermal imaging) method may in embodiments have broad applications for H2O, CO2, CO and N2 reduction applications which all contain different phenomena and challenges.

Multiple electrochemical cells 1 may be stacked and/or arranged in an arrangement 100. This is very schematically depicted in Fig. 2. There, an arrangement 100 is given comprising a plurality of electrochemical cells la, lb, lc, Id, le, . The arrangement

100 further comprises an infrared analyzing system 5 and a control system 7. The infrared analyzing system 5 may comprise just one infrared sensor 50 configured outside of the plurality of cells 1, especially at a position external of the plurality of cells 1, for sensing through the windows 17 of at least a subset of the cells 11 infrared radiation 51 from the gas- diffusion electrode 15, which is schematically depicted with the sensor 50 most remote from (all of) the cells 15. Yet, the infrared analyzing system 5 may comprise a plurality of infrared sensors 50, wherein each sensor 50 is configured for sensing through the windows 17 of respective cell 11 infrared radiation 51 from the gas-diffusion electrode 15. This is indicated with the single infrared camera 53 that monitors only one cell 1, lc. It will be understood that many intermediate configurations are possible (e.g., one sensor for two, or three or even more cells 1. The control system 7 is further configured for analyzing a sensor signal provided by the one or more sensors 50 and/or controlling an operation of the one or more electrochemical cells 1.

Using the arrangement 100, the high throughput method for analyzing a gas- diffusion electrode 15 in an electrochemical cell 1 may be carried out. The high throughput method may especially comprise providing the arrangement 100 and simultaneously operating at least a subset of the plurality of electrochemical cells 1, thereby individually controlling operating parameters for each of the operated electrochemical cells 1. The method further comprises: for each of the operated electrochemical cell 1, sensing through its window 17 infrared radiation 51 from the gas-diffusion electrode 15, determining a temperature distribution over at least part of the gas-diffusion electrode 15 (based on the sensed infrared radiation 51); and determining an effect of the operating parameters on the temperature distribution over at least part of the gas-diffusion electrode 15.

The term “plurality” refers to two or more. Furthermore, the terms “a plurality of’ and “a number of’ may be used interchangeably.

The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. For numerical values it is to be understood that the terms “substantially”, “essentially”, “about”, and “approximately” may also relate to the range of 90% - 110%, such as 95%-105%, especially 99%-101% of the values(s) it refers to.

The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’.

The term “and/or” especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species".

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.