FI20245258A1

FI20245258A1 - A flow field plate, an electrolysis cell, an electrolytic device and methods for preparing the electrode, the electrolysis cell and the electrolytic device

Info

Publication number: FI20245258A1
Application number: FI20245258A
Authority: FI
Inventors: Pasi Keinänen
Original assignee: Liquid Sun Oy
Priority date: 2024-03-01
Filing date: 2024-03-01
Publication date: 2025-09-02
Also published as: WO2025181434A1

Abstract

A flow field plate comprising one or more open faced non-engraved channels on a surface of the flow field plate. An electrolysis cell comprising a membrane electrode assembly comprising an anode combined with the flow field plate, a cathode combined with the flow field plate, and an ion exchange membrane between the anode and the cathode, wherein one or more of the flow field plates comprises one or more open faced non-engraved channels on a surface of the flow field plate. An electrolyzer comprising one or more of the flow field plates or one or more of the electrolysis cells. A method for preparing a flow field plate, an electrolysis cell and an electrolyzer.

Description

A flow field plate, an electrolysis cell, an electrolytic device and methods for preparing the electrode, the electrolysis cell and the electrolytic device

Field of the application

The present application relates to a flow field plate, to an electrolysis cell comprising the flow field plate, and to an electrolytic device comprising the flow field plate or the electrolysis cell. The present application also relates to a method for preparing the flow field plate, to a method for preparing the electrolysis cell and to a method for preparing the electrolytic device.

Background

A Membrane Electrode Assembly (MEA) usually comprises a proton conducting polymeric membrane (PEM) sandwiched between anode and cathode layers.

These may comprise, or be sandwiched between, flow field plates (FFP). The FFP has several roles, for example separating gases between the half cells and neighbouring cells in a stack, providing an electronic conducting medium between the anode and cathode, providing a specific flow field design containing channels allowing even distribution of the reaction gases, providing a solid structure for the

MEA, and facilitating water and heat management.

Generally, flow field plate materials are categorized into metal-based and graphite- based materials. Metal-based materials provide high electrical and thermal conductivity, low gas permeability, mechanical strength, as well as low thickness.

However, the exhibit low corrosion resistance, which may result in ionic leaching

S breaking the mechanical and chemical balance, and decreasing the hydrophobicity

N of the electrolyte membrane, resulting in problems in oxygen transport. Further, a & highly resistive oxide layer may form on the membrane, which has a negative 5 30 effect on electrical performance. = > Graphite-based materials provide high corrosion resistance and low density, but

OD exhibit high gas permeability and low mechanical strength, for example brittleness, 3 which may result in unsatisfactory processing, high weight and high cost. Also, < 35 graphite is unstable and spontaneously exfoliated with respect to chemical oxidation.

Usually metal-based materials are used to overcome the problems of corrosion and oxidation, while graphite-based materials are used to enhance gas tightness and processability.

However, the prior art plates the channels are obtained by engraving, which makes the preparation process slow and expensive. Figure 1 shows an example of a metallic flow field plate having engraved channels.

There is a need to find new types of flow field plate structures, materials and methods for preparing thereof. It is desired to provide flow field plates and devices comprising thereof, which can be manufactured with low costs and in industrial scale to fulfil the increasing need of devices and electrodes required in electrolytic applications, such as production of hydrocarbons, carbon monoxide and other products. It is also desired to obtain devices with low cost, low weight and high mechanical and chemical durability.

Summary

With the present solution it was possible to obtain electrodes and devices utilizing the electrodes, which could overcome prior art problems. It was possible to avoid laborious, slow and expensive prior art preparation methods. It was also possible to utilize materials and structures, which were not found useful or which were not even considered in the prior art.

In the present invention it was found out that plastic materials could tolerate the conditions used in current electrolytic applications, wherein the temperature,

S pressure and used chemicals were not found detrimental to the materials. This

N enables providing new production methods for forming flow field plates, which are & fast, simple and inexpensive and which can provide flow field plates and 5 30 electrodes comprising the plates, as well as devices comprising the electrodes,

I which are inexpensive, light in weight and can be produced in industrial scale. This > provides benefits in a broad production chain, starting from manufacture of flow

LO field plates to manufacture and end use of devices, such as electrolyzers.

N

I 35 It was also found that the new methods can be applied to other materials as well, thus enabling the effects with a broad range of materials. Even further, it was found that the materials can be formed into new types of structures, and also existing materials can be used in the present flow field plates. The new structures include mesh structures and the like non-continuous structures.

The present application provides a flow field plate, such as an electrically conductive flow field plate, comprising one or more open faced non-engraved channels on a surface of the flow field plate.

The present application also provides an electrolysis cell comprising -a membrane electrode assembly comprising -an anode combined with a flow field plate, such as an electrically conductive flow field plate, for example wherein the anode is a gas diffusion anode, -a cathode combined with a flow field plate, such as an electrically conductive flow field plate, for example wherein the cathode is a gas diffusion cathode, -an ion exchange membrane between the anode and the cathode, wherein one or more of the flow field plates comprises one or more open faced non-engraved channels on a surface of the flow field plate.

The present application also provides an electrolytic device comprising one or more of the electrodes or one or more of the electrolysis cells, preferably arranged as a stack.

The present application also provides a method for preparing a flow field plate, the method comprising -providing a blank flow field plate without channels, and

S -forming one or more open faced flow field channels to a surface of the blank flow

N field plate by embossing, debossing or stamping. 3 = 30 The present application also provides a method for preparing an electrolysis cell,

I the method comprising providing one or more of the flow field plates, and > assembling an electrolysis cell comprising

OD -a membrane electrode assembly (MEA) comprising 3 -an anode comprising and/or combined with the flow field plate, and/or < 35 -a cathode comprising and/or combined with the flow field plate, and -an ion exchange membrane between the anode and the cathode.

The present application also provides a method for preparing an electrolytic device, the method comprising providing two or more of the electrolysis cells, and assembling an electrolytic device comprising a stack of the electrolysis cells.

The main embodiments are characterized in the independent claims. Various embodiments are disclosed in the dependent claims. The embodiments and examples recited in the claims and the specification are mutually freely combinable unless otherwise explicitly stated.

Brief description of the figures

Figure 1 shows a prior art flow field plate made of metal

Figure 2 shows an example of a single cell electrolyzer (Figure 2A), an example of a cathode gas diffusion electrode (Figure 2B) and a setup comprising an electrolyzer connected to a power supply (2C). The legends are: 1. Cathode flow field plate, 2. Anode flow field plate, 3. Polymer Electrolyte Membrane, 4.

Cathode gasket, 5. Anode gas diffusion electrode (GDE), 6. Cathode gas diffusion electrode (GDE), 7. Anode gasket, 8/9. Flow channels, 10. Inlet for catholyte, 11.

Outlet for anolyte, 12. Outlet for catholyte and gaseous products, 13. Inlet for anolyte, 14. Cathode electrical connection point, 15. Anode electrical connection point. 16. Membrane electrode assembly (MEA), 17. GDE composition, 18.

Macrofibrous layer, 19. Microporous layer, 20. Catalyst layer, 21. Electrolyzer, 22.

Power supply, 23. Computer, and 24. Electrical wires.

Detailed description

N

N In this specification, percentage values, unless specifically indicated otherwise, are & based on weight (w/w, by weight, or wt%). If any numerical ranges are provided, = 30 the ranges include also the upper and lower values. In specific examples the

I embodiments specified with the open term “comprise” may be further limited with a > closed term “consisting of”. 3 The present application provides a flow field plate, which may be an electrically < 35 conductive flow field plate, which may be a flow field plate comprising an electrically conductive portion and/or a flow field plate comprising or consisting of electrically conductive material. A flow field plate without any conductive portion or which is not conductive may be a blank for a flow field plate. The flow field plate may be for, and may be used in, an electrode, such as an electrode of an electrolysis cell or an electrolytic device disclosed herein, for example an anode and/or a cathode. The flow field plate may be also called as a current collector plate. The flow field plate comprises or is a planar structure, and it typically has 5 two large surfaces, wherein at least one of the large surfaces comprises open faced channels. The flow field plates comprise sides, which have the shortest dimension of the plate and may define the thickness of the plate, such as the highest thickness.

Flow field plates may be provided as bipolar plates and/or in bipolar configuration, which are especially useful in a stack, and/or as monopolar plates and/or in monopolar configuration, which are especially useful in an individual electrolysis cell. In applications relating to electrolytic devices and the like devices comprising two or more, such as a plurality, of electrolysis cells arranged in a stack, the flow field plates may be bipolar or monopolar plates. Bipolar plates may comprise open faced channels on both sides, i.e. on both largest surfaces.

The present flow field plates (also called as “plates” herein) play an important role on the chemical reactions of an electrolysis cell, such as a fuel cell, for example proton-exchange membrane fuel cells (PEMFC), as the channel structure can effectively provide distribution of the agents to the electrochemical reactions. The flow field plate supplies fuel (hydrogen, Hz), and oxidant (air, O2) to the membrane electrode assembly, removes water, and collects electrons produced. The flow field plate also provides mechanical support for the cell or the stack, and to any additional parts such as porous and/or sheet like parts. The plate also enables providing a conductive medium between the anode and cathode to maintain

S desired operation of the cell. On the other hand, the flow field plates can effectively

N mitigate the bad effects of corresponding chemical reactions, such as heat, vapor, & water and liquid water, since these products can be discharged outside the cell 5 30 through the channels. With the present plates, the effects of high humidity and

I chemicals, which under a certain electrical potential easily induces severe > corrosion for prior art flow field plates and in turn reduces the service life of fuel

OD cell, could be reduced or avoided.

N

I 35 In the present invention it was found out that it is not necessary to form the flow field plates in a traditional way wherein the channels are formed on a metal or graphite plates by engraving. Alternative materials and/or methods for forming the plates and channels are presented herein, which can provide similar or even better properties compared to prior art solutions.

The present disclosure provides an electrode comprising an electrically conductive flow field plate, which may be a flow field plate comprising an electrically conductive portion, and optionally a catalytic portion, wherein the flow field plate comprises one or more open faced channels, i.e. flow fields, on a surface of the flow field plate. The flow field plate may be configured or designed to receive the catalytic portion. Alternatively, or in addition, the flow field plate may comprise the catalytic portion, such as a coating of catalyst on an electrode, such as wherein the catalytic portion is a gas diffusion electrode or is a part of a gas diffusion electrode, which may be on the flow field plate or part thereof, or otherwise incorporated in the flow field plate or part thereof. Open faced channels are open to the interior of an electrolysis cell when the flow field plate is installed in the cell.

The open faced channels enable flow and contact of liquid and agents contained in the liquid, i.e. are in fluid and/or gas communication, with an electrode and for example with the catalytic portion of the cell, which may be in a form of a sheet. In the present solutions the channels are preferably non-engraved, ie. they are formed with other suitable methods, such as methods enabling processing of the used materials, such as plastic or suitable metals.

An electrolytic device, such as an electrolysis cell or an electrolyzer, uses electricity to split water or other components into their constituent elements through electrolysis. An electrolytic device comprises an anode and a cathode, which are arranged in or as a cell, which may be placed or located in a container, which can receive liquid, such as electrolyte in the form of liquid, usually aqueous

S liguid. The anode and the cathode are connected or connectable to a source of

N electrical energy. The portion of an electrolyte near the cathode, especially in a & cell in which the cathode and anode are in separate compartments, may be called 5 30 catholyte. Correspondingly the portion of an electrolyte near the anode, especially

I in a cell in which the cathode and anode are in separate compartments, may be > called anolyte. In general, the anode operates to complete the redox reaction cycle

O by oxidation reaction of water resulting in oxygen gas (O2) formation. The 3 reduction of CO2 occurs on the cathode via a series of proton-electron transfer < 35 processes resulting in formation of the specific reaction product distribution.

The electrolysis cell may have a casing, a frame or a body, including one or more inlets and one or more outlets for liquids and/or gases, and connections for a source of electrical energy. The flow field plates may form the casing, the frame or the body or a part thereof. The anode and the cathode, and/or the flow field plates, are connected or connectable to a source of electrical energy, such as an external source of electricity, which may be controllable. Electric power, such as with desired and/or controlled voltage and/or current, may be applied to the anode and the cathode, and/or to the flow field plates, to obtain electrochemical, such as electrolytic, reactions in the liquid in contact with the anode and the cathode. The flow field plates may be considered as part of the electrodes, or as the electrodes.

The flow field plate may comprise one or more connections for electric energy, — more particularly electricity. The connection may comprise one or more connectors for wiring, or apertures or the like receiving portions for the connectors and/or the wiring.

The electrolytic device may comprise an ion exchange membrane, jie. an electrolyte membrane, between the anode and the cathode. The ion exchange membrane may be a polymeric membrane, such as comprising perfluorosulfonic acid. The ion exchange membrane allows the passage of protons to pass to the cathode while restricting the passage of electrons. Other substances passing through the ion exchange membrane would disrupt the chemical reaction. The membrane may be called as a polymer electrolyte membrane (PEM). The polymer electrolyte membrane may refer to any types of suitable membranes, such as anion exchange membranes (AEM), cation exchange membranes (CEM) or bipolar exchange membranes (BPM)

The flow field plate may comprise one or more apertures for inlets and outlets, for example at the sides having the shortest width/thickness. Such apertures may be

S located on a side of a stack of cells or may be connected to the side of the stack,

N wherein connectors and/or tubes for incoming and outcoming liquid and/or gases & may be connected to the apertures or other receiving parts. In or inside the plates 5 30 the apertures may be connected to the channels. The one or more channels may

I be therefore connected from one end to an inlet and from other end to an outlet > thus allowing circulation of liquid and/or gas through the electrode or cell. 3 The flow field plate may comprise one or more apertures for attaching to the other < 35 parts, such as for assembling the cell, for example with one or more screws, bolts, pins or the like attaching means. The parts of the cell may be sandwiched and preferably attached with the attaching means to obtain a cell. The cell may be designed as a single cell or as a stack of cells in bipolar and/or monopolar configuration, wherein the cells are preferably designed to fit each other i.e. they may have compatible sides and/or attaching portions, which allow the cells to be attached to each other.

With the present methods and materials, it is possible to obtain flow field plates with a varying thickness, area and/or other dimensions. The depth of the channels may be adjusted to a desired depth range.

The longest sides may have a length in the range of 5-50 cm, such as 5-30 cm, for example 10-25 cm. The channeled portion or area may be surrounded by unchanneled and/or elevated areas at the edges of the largest surfaces, which may form a wall around the channeled area. The channeled area may comprise a lowered area, for example 0.5-3 mm, such as 0.5-2 mm, lower than the surrounding area, which enables placing one or more sheet form parts on the channeled area, such as porous material, which may comprise catalysts, and/or one or more membranes or the like. When two flow field plats are sandwiched, a space is formed between the plates for circulation of liquids and/or gases and for reactions to take place.

The depth and/or width of open faced channels may be adjusted according to needs and may be implemented in a large range. The present materials and methods do not limit the depth or the width, or the shape of the channels. In one example the one or more channels on the surface of the flow field plate have a depth and/or width in the range of 0.3-1.0 mm. With the present materials and methods, it is possible to form complex channels having different shapes, structures and dimensions. Preferably the channel depth, or combined depth of 5 channels in both sides in the case of bipolar plate, is lower than the thickness of

N the flow field plate. 3 = 30 The thickness of the flow field plate may be implemented in a large range. It may

I be desired to obtain a low thickness, such as in the range of 1.0-5.0 mm, or 10.0- > 3.0 mm, even 1.0-2.0 mm, to enable a high number of cells in a stack or otherwise

OD compact form of a cell. If, however, a higher thickness is desired, for example to 3 enable deep open faced channels and/or large or complex inner channels, or for < 35 other structural reasons, it is also possible to prepare plates with higher thickness, as the material costs and manufacturing process do not substantially increase with the present materials and methods.

The electrolysis cell or the electrolytic device may be designed and/or configured to feed raw material or provide and/or obtain a feed of the raw material, such as liquid comprising or containing carbon dioxide or source thereof i.e. the catholyte, to the cathode and/or water or other aqueous solution, such as a solution comprising one or more electrolytes i.e. the anolyte, to the anode.

The present disclosure provides an electrolytic device or device arrangement, such as an electrolyzer, comprising one or more of the electrolysis cells, such as comprising one or more gas-fed polymer membrane electrolyte electrolysis cells, or one or more devices comprising the cell(s), the cell comprising a membrane electrode assembly (MEA). The electrodes may be gas diffusion electrodes (GDE) such as shown in Figure 2B, which comprise a gas diffusion layer (GDL) and a catalyst layer (CL). The membrane electrode assembly comprises an anode GDE, a cathode GDE and a membrane between the anode and the cathode, which assembly is encased between an anode flow field plate and a cathode flow field plate.

In most cases the electrolysis cell comprises -an anode comprising or combined with a flow field plate, i.e. a current collector, — such as a gas diffusion anode, and/or -a cathode comprising or combined with a flow field plate, such as a gas diffusion cathode, and -an ion exchange membrane between the anode and the cathode. The flow field plate, in the anode and/or in the cathode, is preferably the present flow field plate, which comprises the one or more open faced channels on a surface of the flow field plate, such as the non-engraved channels. The electrodes are in contact with

S a corresponding flow field plate, such as a cathode 6 is combined with a

N corresponding cathode flow field plate 1 so that the channels 8 of the cathode flow & field plate are in fluid and/or gas communication with the cathode 1 (Fig. 2A). In 5 30 analogous manner the anode 5 is combined with a corresponding anode flow field

E plate 2.

LO There are several MEA configurations. Preferred configurations include 5-layer 3 systems, where two catalyst layers (one for anode and one for the cathode) are < 35 attached to two gas diffusion electrodes (GDEs) and sandwiched between one polymer electrolyte membrane (PEM) resulting in a total of 5 layers. Another configuration includes 3-layer configuration which is essentially the same as the 5 layer but without the two gas diffusion layers (GDLs), and instead the catalyst layers are directly coated on either side of the PEM.

An electrolytic device, which may be an electrolyzer, is a device or a device setup, a system and/or an assembly, or a combination thereof, comprising one or more electrolysis cells, and any associated components, such as one or more of the ones disclosed herein. The electrolytic device may comprise a frame, a casing, a cover and/or the like structural parts, which may include the one or more electrolysis cells. Figure 2A shows an example of an electrolytic device showing one electrolysis cell.

An electrolytic device in general is a device that uses electricity to split water and/or other components into their constituent elements through electrolysis. An electrolytic device as described herein refers to a device setup, such as shown in

Figure 2C, comprising parts and/or components required to operate the device, including the electrolysis cell(s) and any required other parts and/or components, such as inlets and outlets, and any operating and/or controlling parts and/or components. An electrolytic device may comprise a plurality of electrolysis cells or cell assemblies arranged as a stack, for example wherein the electrolysis cells are flow cells arranged as one or more stack(s). A plurality may refer to two or more, five or more, ten or more, up to hundreds of cells, for example to 2-500, 2-10, 10- 500, 10-100 or 10-50. An electrolytic device may comprise the electrolysis cell stack(s), pumps, valves, storage tanks, a power supply, a separator, one or more sensors, and/or other operating components. Electrolysis occurs within the cell stacks when an electric current is applied in the system across the electrolytes.

The cells in a stack may be connected to the electric current in parallel and/or in

S series. Bipolar plates cannot be connected only in parallel. The electrolytic device

N may be a CO» electrolytic device. 3 = 30 Electrolyzers may be classified in three categories: alkaline electrolyzer, the proton

I exchange membrane (PEM) electrolyzer, and solid oxide electrolyzer (SOE). The > present electrolyzer is preferably a proton exchange membrane electrolyzer. PEM

OD electrolyzers contain a proton exchange membrane that may use a solid polymer 3 electrolyte. When an electrical current is applied to the cell of the electrolyzer < 35 during water electrolysis, the water splits into hydrogen and oxygen. The hydrogen protons pass through the membrane to form H? on the cathode side.

The electrolyzer may be a gas-fed electrolyzer, at least for the cathode side, and it may comprise one or more gas-fed polymer membrane electrolyte electrolysis cells. The anode side may use a liquid anolyte/electrolyte. The gas may comprise

COo, such as humidified CO? gas, or any other applicable gas, such as inert gas.

The electrolyzer may be a CO: electrolyzer.

The electrolyzer may be a zero-gap electrolyzer, such as a zero-gap CO: electrolyzer. Similarly, the electrolysis cell may be a zero-gap electrolysis cell. A zero-gap electrolyzer, or a zero-gap electrolysis cell, has no gap between the cathodes, anodes and the polymer electrolyte membrane (PEM). A zero-cap two- compartment electrolyzer or cell can be specifically used for CO? conversion to non-liquid products.

In zero-gap electrolyzers both catalyst layers in the cathode and anode GDEs are in direct contact on either side of the membrane. Zero-gap electrolyzer typically constitute in a 2-compartment electrolyzer. In “non zero-gap” electrolyzers at least one side of the membrane is in direct contact with the catalyst and other is separated by electrolyte. “Non zero-gap” typically constitute to 3-compartment electrolyzers.

The present disclosure provides an electrolytic device comprising one or more flow field plates, one or more electrodes or one or more electrolysis cells disclosed herein. The electrolysis cells may be arranged as a stack. In such case the flow field plates may be bipolar plates comprising channels on both sides of the plate.

In one example an electrolytic device, for example an electrolytic device for 5 reducing carbon dioxide to products, such as to hydrocarbons and/or CO,

N comprises & -one or more, such as a plurality of, the electrolysis cells or cell assemblies 5 30 disclosed herein. = > The electrolytic device may comprise

OD -an inlet for reactant stream and/or feed, such as a source of carbon dioxide, and 3 -an outlet for reaction products, such as a stream and/or feed thereof. < 35

The electrolytic device may be a continuous electrolytic device, which may be used for continuous electrolysis of carbon dioxide, preferably humidified carbon dioxide.

Preferably the electrolytic device comprises two or more of the electrolysis cells. In such case the electrolysis cells may be flow cells arranged as one or more stack(s).

The electrolytic device may comprise, be connected or be connectable to a power source. Any operating and/or active components may be operatively connected to controlling means. The electrolytic device, the electrolyzer, the electrolyzer system or the assembly may be electronically controllable, thus comprising one or more — controlling means. The controlling means may be or comprise one or more electronic control units, which may be programmable, comprising one or more processors, memory, and software configured, when executed with a processor in the control unit, to carry out one or more operations to implement the method, for example to adjust the voltage, current, temperature, pressure and/or flow of liguids and/or gases by controlling and/or adjusting any of the operating components of the device, the system or the assembly. The control unit may be, comprise and/or be connected to a computer. The controlling means may be arranged to maintain one or more of said parameters in a desired range. The controlling means may be arranged, such as programmed, to monitor one or more properties from the device, the system, and/or the assembly, for example as a function of time, and as feedback to the monitored properties carry out one or more control actions in the device or the system to adjust the function of the device to carry out the present method.

In one example the electrolytic device comprises -one or more, such as a plurality, for example two or more, of the electrolysis cells 5 disclosed herein, preferably arranged as a stack, and

N -a power source and/or a power supply and/or wherein the electrolytic device is & connectable to a power source and/or a power supply. The power supply or the 5 30 power source is arranged to provide electric current to the anode and the cathode,

I or to the electrolysis cell(s). The electrolytic device may comprise connectors > and/or wiring for the power source or the power supply. The power supply may

OD refer to a device controlling the application of power and/or properties thereof, 3 which usually converts electric current from a source to the correct voltage, < 35 current, and frequency to power the load. Power supply may be referred to as an electric power converter. The power supply may be controllable, for example by controlling means such as a control unit, to which it may be operatively connected, so that desired voltage and/or current may be obtained and provided to the anode and the cathode. The power timing, pulsing, frequency, and/or the like parameters may be also controlled. In one example the power supply comprises or is a potentiostat or a galvanostat, which may be used for controlling the present methods and/or activating methods.

The electrolytic device may comprise flow and/or pressure control means arranged to control the flow and/or pressure in the electrolysis cell and/or in the electrolytic device. The pressure control means may include one or more sensors for detecting flow and/or pressure in a cell or the electrolytic device, which sensors may be connected to controlling means. The controlling means may be arranged, as feedback to the detected flow and/or pressure, to control one or more devices and/or parameters to adjust the flow and/or pressure in a desired range.

The cathode and optionally also the anode may comprise a catalyst layer on a — support. The cathode may comprise a catalyst layer on a cathode support and the anode may comprise a catalyst layer on an anode support, such as a thin layer of catalyst material disposed on their major surfaces at the interface with the interposed membrane. The catalyst may be different in the cathode and in the anode. In the present invention it was found out how to obtain suitable catalyst in the cathode to promote desired electrolytic reactions. The present cathode can be used with any suitable anode and in any suitable device, device arrangement and/or process.

The anode comprises anode support, which may comprise or be same material as the cathode support, or it may comprise or be different material. The anode may or may not contain a catalyst on the anode support. If the anode comprises a

S catalyst, the catalyst may be different from the catalyst on the cathode support.

N The anode may be prepared by using the same or similar methods, however & preferably from different materials. 5 30

I In one example the cathode support and/or the anode support comprise porous > material, preferably porous electrically conductive material, which may be in a

OD sheet or a layer form, and which may have planar major surfaces, such as carbon 3 fiber paper. The cathode support is preferably a cathode support layer and/or the < 35 anode support is preferably an anode support layer. A gas diffusion electrode can be obtained by using such a porous electrode support. A gas diffusion electrode comprises the catalytic portion, such as a catalyst layer, as shown in Figure 2B.

The cathode support and/or the anode support may be a gas diffusion layer (GDL), which may comprise two layers: a macrofibrous layer (a backing layer) and a microporous layer (MPL). The catalyst layer (CL) may be applied and/or adhered to or is on the microporous layer.

The present electrode may be a gas diffusion electrode. A gas diffusion electrode (GDE) comprises a gas diffusion layer (GDL) and a catalyst layer (CL). The anode may be an anode comprising an anode catalyst layer deposited on a gas diffusion layer (an anode GDE). The cathode may be a cathode comprising a cathode catalyst layer deposited on a gas diffusion layer (a cathode GDE).

The anode may be based, or comprise, one or more suitable compounds, such as metal, metal oxides, mixed metal and/or mixed metal oxides of Ir, Ru, Rh, Pt, Ni,

Fe, such as iridium, IrO2, NiFe, transition metals, and the like materials.

Commercially available anode materials may be used in the present devices and methods.

Disclosed is a metal alloy catalyst, i.e. a mixture of metals, which metal alloy catalyst may be used in electrolytic applications, such as in a cathode. The metal alloy catalyst may comprise or be in a form of nanoparticles.

A catalyst may comprise one or more transition metal and/or alloy thereof. A catalyst may comprise one or more elements selected from the group consisting of

V, Cr, Mn, Fe, Co, Ni, Cu, Sn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Ir,

Pt, Au, Hg, Al, Si, In, TI, Pb, Bi, Sb, Te, U, Sm, Tb, La, Ce, and Nd. In the present case it was found advantageous to use copper in the catalyst, preferably in

S combination with silver.

O

N d The porous material, such as a sheet or a layer thereof, may be applied onto the = 30 open faced channels, and it may be attached to the plate by using suitable

I attaching means, and/or it may be immobilized in the electrode or cell structure > when the electrodes are sandwiched, for example in the cell. 3 In the present invention it was found out that it is not necessary to form the flow < 35 field plates in a traditional way wherein the channels are formed on a metal or graphite plates by engraving. Methods using a die to form the channels were found suitable for processing various materials suitable for flow field plates, including metal materials but also plastics and composite materials. One method found especially advantageous for forming the channels was embossing, which could be implemented with plates made of a variety of materials. Embossing is a process, which can produce raised or sunken designs. They are usually produced using a specialized embossing machine or using a male and female die set. A process creating sunken designs may be also called debossing. In the present method only one side of a plate may be embossed at a time, or both sides in case of bipolar plates.

One method useful for forming the channels is stamping. The stamping process may use a manufacturing press to indent the channels into the material.

In one embodiment the one or more open faced channels on the surface of the flow field plate is/are embossed, debossed or stamped channels, or are obtained by corresponding methods. Embossing, debossing or stamping can be carried out — with any suitable embossing, debossing or stamping device with a suitable die.

Embossing, debossing or stamping can be implemented as an industrial process, wherein each plate can be processed in one step thus forming the channels in very fast process, which may use a pressing device or the like device, such as manufacturing press. The formed channels were found comparable to prior art engraved channels in quality and functionality. Thus, the complex engraving process, which is slow and also produces waste material, could be avoided.

It was found out that the flow field plates can be made of plastic, such as thermoplastic polymers and/or thermosetting polymers. The plastic flow field plates may comprise 60% by weight or more plastic, such as 80% by weight or more, for

S example 90% by weight or more. This may be the case in composites and/or

N wherein the plate comprises additional electrically conductive material, such as & metal. The plates, such as the body of the plates, may consist of the plastic, and in 5 30 such case the plates may be for example coated with conductive material. The

I plastic-containing flow field plates could tolerate the moderate conditions used in > most present electrolytic processes, such as temperatures of 100 °C or below, for

LO example 20—100 °C, 20-80 °C, or 20-60 °C. Also, the pressures of the processes 3 are usually in the range of 1-5 bar, such as 1-5 bar, which can be well tolerated < 35 by the plastic-containing materials. Also, the reagents, such as anolyte and catholyte, used in the processes does not harm the plastic materials, which are chemically inert and actually more corrosion tolerant than the prior art metals or graphite. Plastics can also tolerate oxidation and mechanical stress, and they are for example not brittle. With plastics it is possible to obtain very light plates, which provide benefits in the handling and transportation of the plates, in the assembly of devices and in the final devices. The cells, stacks and electrolytic devices comprising the present plates comprising light materials are also light in weight and can be easily moved, for example transported to customers, transported to a site of use, and/or arranged, serviced, and handled. These features, and also other features discussed herein, benefit several operators ranging from production, supply, storing, and transportation to manufacture of devices and to final use.

In one embodiment the one or more of the flow field plates comprises one or more plastic polymers, such as thermoplastic polymers and/or thermosetting polymers.

The thermoplastic polymer may comprise any suitable thermoplastic polymer or a mixture thereof, which may be plastic. Preferably the plastic polymers can be effectively processed by the present methods, such as by embossing and/or by moulding. Suitable plastic polymers include one or more of synthetic polyamide, polytetrafluoroethylene, polyvinylidene fluoride (PVDF), perfluoroalkoxy alkanes (PFA), ethylene chlorotrifluoroethylene (ECTFE), polychlorotrifluoroethylene (PCTFE), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), and fluorinated ethylene propylene (FEP). These polymers provide good mechanical properties, chemical resistance, temperature resistance and stability, wear resistance, and dielectric properties, which makes them especially suitable as flow field plate materials in the present applications. These polymers can be used as base material for the present composites, which may include reinforcing and/or conductive material.

S The flow field plates can be also made from composite materials, such as plastic

N composites, for example plastic-carbon fiber composites, plastic-metal fiber & composites, plastic-ceramic composites and the like plastic-reinforcing component 5 30 composites. The plastic may comprise any suitable plastic polymer, such as one

I or more disclosed herein. The composite may comprise a conductive component, > which may be also a reinforcing component. 3 Plastics and composites can be processed with a variety of methods, and it is < 35 possible to mold the final flow field plates from plastic-containing material by common moulding methods, such as injection moulding or extrusion moulding.

Injection moulding is a manufacturing process for producing parts by injecting molten material into a mold. A suitable mold may be provided, which enables forming the desired channels and also the overall shape of the plate. Material for the part is fed into a heated container, and injected into a mould cavity, where it cools and hardens to the configuration of the cavity. A blank plate may be formed by injection moulding, such as comprising the overall shape of the flow field plate and preferably any recesses and/or channels therein. However, the channels may be also formed with other methods such as by embossing, debossing or stamping.

The flow field plate is electrically conductive, which may refer to the flow field plate as a whole, or to an electrically conductive portion of the flow field plate. The electrically conductive portion is required to enable the electrolytic reactions. The flow field plate as a whole may form the electrically conductive portion, if the plate is made of or comprises conductive material. If non-conductive materials are used as the base material of the plate, such as non-conductive plastics, an additional electrically conductive portion shall be provided or arranged in the flow field plate.

The electrically conductive portion may be formed as a coating, which may be full or partial coating on the plate, for example at least covering the channeled portion or area. The coating may be formed before or after forming the channels. For example, at least the surface comprising the channels, or where the channels are to be formed, may be coated. The conductive portion or part thereof may be provided as a separate portion or part, and/or an external part, such as one or more conductive sheets or conductors, may form at least part of the conductive portion.

In one embodiment the electrically conductive portion comprises an electrically conductive coating. The electrically conductive coating may comprise one or more metals. The coating may be formed with any suitable method, such as by painting,

S spraying, such as flame spraying, sputtering etc. A suitable coating solution or

N dispersion may be provided, which contains one or more conductive metals or & precursors thereof, such as silver, copper, aluminum, nickel, for example as 5 30 nanoparticles. = > In one embodiment the electrically conductive portion comprises electrically

OD conductive plastic or composite. The plastic may be or comprise thermoplastic 3 polymer, such as electrically conductive thermoplastic polymer or thermoplastic < 35 polymer comprising electrically conductive additive and/or material, for example any of the ones disclosed herein. The electrically conductive plastic or composite may be obtained by incorporating one or more suitable conducting additive and/or material to the base material, i.e. the plastic or composite. In example the electrically conductive plastic or composite comprises one or more of carbon fillers, such as carbon black, graphite, carbon fibers, nanostructured carbon, such as carbon nanotubes, or the like, metal fibers and/or particles, conductive polymers, and/or the like. Also, the conductive plastic or composite may be coated — with electrically conductive coating.

The channels may be formed in any suitable form. For example, the one or more channels on the surface of the one or more flow field plates may comprise a design selected from serpentine, parallel, pin-type, mesh-type, fractal type, and — interdigitated flow fields.

The serpentine design is a traditional design and comprises a single continuous channel covering the whole area of the FFP. A single inlet is connected to a single outlet. The reactant gases can move everywhere from the FFP. The serpentine design has emerged as an industry standard because of its robust performance and ability to reproduce results. The serpentine design may comprise a single serpentine channel, double serpentine channel, a plurality of, such as three or four, serpentine channels, or a symmetric arrangement of a plurality of, such as four, serpentine channels.

In examples the one or more of the flow field plates comprises non-metal, non- graphite and/or non-composite material. The non-metal material may specifically refer to non-steel/non-iron materials and/or to other materials not commonly used in prior art flow field plates. The non-composite may exclude plastic composites.

Metals can be used as base material in the present flow field plates in case the 5 metal can be processed with non-engraving methods, such as by the embossing.

N In one embodiment the one or more of the flow field plates comprises metal & comprising embossed, debossed or stamped channels. More particularly the plate 5 30 may be or may be made of metal and the channels may be obtained by

I embossing, debossing or stamping. a

LO The metals may comprise steel, titan and/or other suitable metals, or combinations 3 thereof. For example, one side of the plate may comprise steel and/or the other < 35 side may comprise titan. The metal(s) may be also included in a non-metallic plate. The metal may be corrosion-resistant metal, such as stainless steel, carbon steel, galvanized steel, aluminum, or red metals such as copper, bronze or brass.

The flow field plates may be made of non-continuous material, such as mesh or the like material comprising fabric, grid or the like structure, for example comprising fibers, wires, and/or the like elongated material. In one embodiment one or more of the flow field plates comprises a mesh structure, wherein the channels are formed by mesh apertures. A mesh structure may comprise one or more meshes, such as wire mesh. A mesh may be a grid and/or a network. The mesh may comprise or be made of metal. In one embodiment the mesh structure comprises a metal mesh. The mesh may comprise steel, titan or a combination thereof. The mesh may also comprise or be made of other materials, such as the plastics or the composites disclosed herein. The materials may be processed into suitable form, such as into elongated forms such as fibers and the like, for example by extrusion moulding, which can then be formed into a mesh structure.

Conductive portions may be formed by any suitable method, such as by coating and/or by incorporating conductive material to the plastic, composites or the like, in the same manner as described herein for continuous materials.

In a mesh structure there are necessary no predetermined flow channels for the liquid. This is advantageous in certain applications. For example, very efficient liguid flow can be obtained, the catalysts can be efficiently integrated in the mesh structure, and/or the mesh itself can act as an anode and/or a cathode. This is useful for example in structures wherein the casing, the body or the frame of a cell or an electrolytic device is made of polymeric material, such as organic polymers, for example plastics. A mesh structure can provide a very large reaction surface, which increases the efficiency of the electrode and the devices comprising the electrode.

S The present disclosure provides a method for preparing a flow field plate for an

N electrode, which may be any of the electrodes disclosed herein, the method & comprising 5 30 -providing a blank flow field plate without channels, and

I -forming one or more open faced flow field channels to a surface of the blank flow > field plate by embossing. 3 The blank flow field plate may have the form of the final flow field plate except that < 35 no channels and/or conductive portion is/are included. The blank flow field plate may comprise continuous material, such as in a form of a sheet, a block or the like, which can be processed into a form of the present plate. In the case of bipolar plate channels may be first formed on a first side and subsequently to a second side. If the method for forming the channels enables it, the channels may be also formed on both sides simultaneously. The blank flow field plate may comprise or be made of any of the material disclosed herein, such as plastic or metal.

Subsequently the method may comprise coating the flow field plate comprising the one or more open faced embossed, debossed or stamped channels with an electrically conductive coating.

The present disclosure provides a method for preparing an electrolysis cell, the method comprising providing one or more flow field plates and/or electrodes disclosed herein, and assembling an electrolysis cell comprising -a membrane electrode assembly (MEA) comprising -one or more anodes comprising or combined with the flow field plate, and/or -one or more cathodes comprising or combined with the flow field plate, and -an ion exchange membrane between the anode and the cathode.

In one example the electrolysis cell comprises a membrane electrode assembly comprising -one or more anodes comprising or combined with the flow field plate, and/or -one or more cathodes comprising or combined with the flow field plate, and -an ion exchange membrane between the anode and the cathode.

The method may comprise providing the catalytic portion(s), such as porous material, for example one or more gas diffusion electrodes, the ion exchange

S membrane, and/or a casing or parts of a casing and any other parts reguired for

N preparing the cell. 3 = 30 The anode and/or the cathode may comprise bipolar flow field plates, especially if

I the electrolysis cell is prepared and/or provided for preparing a stack of the cells. > Non-bipolar (monopolar) plates may be provided to be placed to the ends of a

OD stack. The electrolysis cell may be prepared by a cell manufacturer, which may be 3 different from the electrode manufacturer. Further, the electrolytic device may be < 35 prepared by an electrolytic device manufacturer by using the electrolysis cells provided by the cell manufacturer.

The present disclosure provides a method for preparing an electrolytic device, the method comprising providing two or more electrolysis cells disclosed herein, preferably bipolar flow field plates, and assembling an electrolytic device comprising a stack of the electrolysis cells, preferably assembling an electrolytic device setup or the like device. The method may comprise providing further components and/or parts required for manufacturing the electrolytic device, which may include one or more components and/or parts such as frame, casing, cover, tubing, wiring, connectors, valves, actuators, attaching means, controlling means, sensors and the like parts, which may be usually required to build an electrolytic device.

The present electrolysis cells or electrolytic device may be used in suitable electrolytic methods. Carbon dioxide may be converted into one or more type of reaction products, ie. compounds, including carbon monoxide, hydrocarbons — and/or CxHyOz products, as well as H2 and Oz as byproducts. In one example the method is a method for converting, such as reducing, carbon dioxide to products, such as to hydrocarbons, alcohols, carboxylic acids and/or CO, the method comprising -providing the electrolysis cell or the electrolytic device, — -providing a source of carbon dioxide, -conveying the carbon dioxide to the electrolysis cell and/or the electrolytic device, -applying electrical current and/or potential to the anode and the cathode to provide electrolysis to electrocatalytically reduce the carbon dioxide to generate products, and -separating and/or recovering the generated products, such as one or more of hydrocarbons, alcohols, carboxylic acids and CO.

N

& The present methods and devices can be used for conversion of CO2 to C1 or C2 3 compounds, such as one or more of CO, HCO, H2CO2, CH3OH, CH4, C2H4,

S 30 CH3CH2OH, CH3COOH, C2Hs, and (COOH). = > Disclosed are any uses of the materials, parts or devices herein for any purpose

OD described herein, such as for carrying out any of the methods or combinations or 3 parts thereof. < 35

Examples

A flow field plate was prepared by providing a blank made of polyamide. The blank was shaped into a shape of a desired flow field plate without channels. The blank was applied into a manufacturing press equipped with a metallic die with a serpentine design channel shape. The blank was pressed with the die by using the press, and a desired serpentine shaped channel design was formed on the blank thus producing a flow field plate with channels. The channel side of the flow field plate was coated with a conductive metal coating.

The flow field plates obtained by pressing the channel designs were combined with gas diffusion electrodes (anode and cathode) and a polymer electrolyte membrane between the electrodes to obtain a membrane electrode assembly. The membrane electrode assembly was used as an electrolysis cell in an electrolyzer, and the function and performance were fully comparable with prior art membrane electrode assembly comprising flow field plates with engraved channels.

Flow field plates made from Teflon® (polytetrafluoroethylene) could be produced with the same method and a membrane electrode assembly comprising the flow field plates exhibited similar function and performance. <

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Claims

1. A flow field plate, such as an electrically conductive flow field plate, comprising one or more open faced non-engraved channels on a surface of the flow field plate.

2. An electrolysis cell comprising -a membrane electrode assembly comprising -an anode combined with a flow field plate, such as an electrically conductive flow field plate, for example wherein the anode is a gas diffusion anode, -a cathode combined with a flow field plate, such as an electrically conductive flow field plate, for example wherein the cathode is a gas diffusion cathode, and preferably -an ion exchange membrane between the anode and the cathode, wherein one or more of the flow field plates comprises one or more open faced non-engraved channels on a surface of the flow field plate.

3. The flow field plate of claim 1 or the electrolysis cell of claim 2, wherein one or more of the flow field plates comprises non-metal, non-graphite and/or non-composite material.

4. The flow field plate of claim 1 or 3 or the electrolysis cell of claim 2 or 3, wherein one or more of the flow field plates comprises one or more plastic polymers, such as wherein the plastic polymer comprises one or more of a 5 synthetic polyamide, polytetrafluoroethylene, polyvinylidene fluoride (PVDF), N perfluoroalkoxy alkanes (PFA) ethylene chlorotrifluoroethylene (ECTFE), 2 polychlorotrifluoroethylene (PCTFE), polyetheretherketone (PEEK), polyphenylene = 30 sulfide (PPS), and fluorinated ethylene propylene (FEP). =

> 5. The flow field plate of claim 4 or the electrolysis cell of claim 4, OD wherein the flow field plate comprises electrically conductive plastic, such as 3 thermoplastic polymer. < 35

6. The flow field plate of any of claims 1 or 3-5 or the electrolysis cell of any of claims 2—5, wherein the flow field plate comprises an electrically conductive portion comprising an electrically conductive coating.

7. The flow field plate of any of claims 1 or 3-6 or the electrolysis cell of any of claims 2-6, wherein the one or more open faced channels on the surface of the flow field plate is/are embossed, debossed or stamped channels.

8. The flow field plate of claim 7 or the electrolysis cell of claim 7, wherein one or more of the flow field plates comprises metal comprising embossed, debossed or stamped channels, or is made of metal and the channels are obtained by embossing, by debossing or by stamping.

9. The flow field plate of any of claims 1 or 3-8 or the electrolysis cell of any of claims 2-8, wherein one or more of the flow field plates comprises a mesh structure, wherein the channels are formed by mesh apertures.

10. The flow field plate of any of claims 1 or 3-9 or the electrolysis cell of any of any of claims 2-9, wherein the mesh structure comprises a metal mesh, such as mesh comprising steel, titan or a combination thereof.

11. An electrolytic device comprising one or more flow field plate of any of claims 1 or 3-10 or one or more electrolysis cells of any of claims 2—10, preferably arranged as a stack, and preferably any associated components.

12. A method for preparing a flow field plate, such as the flow field plate of any of claims 1 or 3-9, the method comprising — -providing a blank flow field plate without channels, and -forming one or more open faced flow field channels to a surface of the blank flow N field plate by embossing, debossing or stamping. N d

13. The method of claim 12, comprising coating the flow field plate = 30 comprising the one or more open faced embossed, debossed or stamped I channels with an electrically conductive coating. a LO

14. A method for preparing an electrolysis cell, the method comprising 3 providing one or more flow field plates of any of claims 1 or 3-10, such as in the < 35 form of bipolar plates, and assembling an electrolysis cell comprising -a membrane electrode assembly (MEA) comprising -an anode combined with the flow field plate, and/or -a cathode combined with the flow field plate, and

-an ion exchange membrane between the anode and the cathode.

15. A method for preparing an electrolytic device, the method comprising providing two or more electrolysis cells of any of claims 2-10, and assembling an electrolytic device comprising a stack of the electrolysis cells. < N O N O <Q O I = 00 LO N LO < N O N