An electrolysis cell and a process for manufacturing thereof

Abstract

The present disclosure relates to an electrolysis cell comprising a porous transport layer which comprises at least one metallic support layer and at least one macroporous layer which comprises titanium particles deposited on the at least one support layer so that the titanium particles are at least partly covered with at least one conductive titanium suboxide surface layer.

Description

[0001] An electrolysis cell and a process for manufacturing thereof

[0002] Technical Field

[0003] The present disclosure relates to an electrolysis cell comprising a porous transport layer which comprises at least one metallic support layer and at least one macroporous layer which comprises titanium particles deposited on the at least one support layer so that the titanium particles are at least partly covered with at least one conductive titanium suboxide surface layer.

[0004] Background

[0005] An electrolysis cell converts water into oxygen and hydrogen and is most efficient when operated at high current density and low cell voltage. There are different variants of electrolysis cells on the market today. However, one of the problems with these cells is that they do not provide high current density at low cell voltage.

[0006] It has been shown that in order to be able to obtain high current density at low cell voltage, it is important to carefully select the components which the electrolysis cell is composed of. One of the most important components is the porous transport layer as it will have a high impact on the ohmic cell resistance which, in turn has an impact on the cell voltage. The ohmic cell resistance is, among others, determined by the contact resistance between the porous transport layers and the catalyst layers.

[0007] The present invention is aiming at solving the above problem by providing an electrolysis cell with a new sort of porous transport layer, which cell will be both more easily produced and provide the desired ohmic cell resistance, i.e. , low cell voltage at high current density.

[0008] Summary

[0009] The present disclosure therefore relates to an electrolysis cell comprising: an anode compartment comprising an anode pole plate; optionally an anode flow field; an electrically conducting anode porous transport layer; and an anode catalyst layer; a membrane; a cathode compartment comprising a cathode pole plate; optionally a cathode flow field; an electrically conducting cathode porous transport layer; and a cathode catalyst layer; wherein the membrane separates the cathode compartment from the anode compartment; and wherein the anode compartment and the cathode compartment are configured to be supplied with a fluid; and wherein at least one of the electrically conducting anode porous transport layer or the electrically conducting cathode porous transport layer is composed of at least one metallic support layer in the form of a three-dimensional open porous structure; and at least one macroporous layer deposited on the at least one metallic support layer wherein the at least one macroporous layer comprises titanium particles; characterized in that the titanium particles are at least partly covered with at least one conductive titanium suboxide surface layer comprising TiOxand / or T O and wherein x is 0.7- 1.3.

[0010] The present electrolysis cell will have low ohmic cell resistance and good water electrolysis efficiency as it has surprisingly been found that the at least one titanium suboxide surface layer will be conductive and enable electrons to pass through the at least one macroporous layer. Without being bound to any theory it is believed that the conductivity is due to the composition of the suboxide surface layer.

[0011] The present disclosure also relates to a process for manufacturing an electrolysis cell as defined hereinabove or hereinafter wherein the process comprises the following step for manufacturing the electrically conductive anode porous transport layer or the electrically conductive cathode porous transport layer:

[0012] Providing at least one metallic support layer

[0013] Providing titanium particles;

[0014] Exposing the titanium particles to a high velocity atmospheric spraying process whereby the at least one macroporous layer is formed during the deposition of the titanium particles on the at least one metallic support layer; characterized in that the high velocity atmospheric spraying process is performed at a temperature below the melting point of the titanium particles and the atmospheric spraying process has an atmosphere having an C>2:CH4 ratio of 0.3 to 0.7 :1. The present process will provide for the formation of the at least one titanium suboxide surface layer as defined hereinabove or hereinafter. Furthermore, the present disclosure relates to an electrolysis cell stack containing at least one electrolysis cell as defined hereinabove or hereinafter. The electrolysis cell stack may either be a proton exchange membrane (PEM) water electrolyser or an anion exchange membrane (AEM) water electrolyser.

[0015] Brief description of the Figures

[0016] The present invention is further described by the following non-limiting figures.

[0017] Figure 1 shows a schematic picture of a cell of a PEM water electrolyser;

[0018] Figure 2 shows a schematic picture of an electrically conductive porous transport layer as defined hereinabove or hereinafter;

[0019] Figure 3A to 3B shows SEM micrographs of a cross section of a reference sample wherein a titanium particle macroporous layer has been deposited by high velocity oxy-air fuel (HVOAF) spraying in a C>2:CH4 ratio of 1.05:1 ; the different magnifications are defined by the scale bars in the respective micrographs;

[0020] Figure 3C to 3D shows SEM micrographs of a cross section of an electrically conductive porous transport layer as defined hereinabove or hereinafter according to the invention deposited by HVOAF spraying in a O2:CH4 ratio of 0.55 to 1 , thus according to the present disclosure; the different magnifications are defined by the scale bars in the respective micrographs;

[0021] Figure 3E to 3F shows SEM micrographs of a cross section of a reference sample wherein a titanium particle macroporous layer has been deposited by high velocity oxy-air fuel (HVOAF) spraying in a O2:CH4 ratio of 0:97:1 ; the different magnifications are defined by the scale bars in the respective micrographs;

[0022] Figure 3G to 3H shows SEM micrographs of a cross section of an electrically conductive porous transport layer as defined hereinabove or hereinafter according to the invention deposited by HVOAF spraying in a O2:CH4 ratio of 0.65 to 1 , thus according to the present disclosure; the different magnifications are defined by the scale bars in the respective micrographs; Figure 4A and 4B shows SEM micrographs of a polished cross section of a spherical titanium particle macroporous layer at different magnifications as defined by the scale bars in the respective micrographs;

[0023] Figure 5 shows X-ray diffractograms of the macroporous layer (solid line) and the spherical powder before being exposed to HVOAF (dashed line);

[0024] Figure 6 shows the polarization curves and iR-free polarization curves (dashed lines) of different PEM water electrolysis single cells of Example 2;

[0025] Figure 7A to 7C shows SEM micrographs of a polished cross section of a titanium non- spherical particle macroporous layer, Figure 7A, shows the result of a high ratio of O2:CH4, Figure 7B and 7C, shows the result of a low C>2:CH4 ratio;

[0026] Figure 8A to 8B shows SEM micrographs of a polished cross section of non-spherical Ti powder deposited on MeliDiff 1500 316L substrate in low magnification (A) and in high magnification (B), the scale bars in the micrographs show the size;

[0027] Figure 9 shows the polarization curves and iR-free polarization curves (dashed lines) of different PEM water electrolysis single cells; and

[0028] Figure 10 shows the polarization curves and iR-free polarization curves (dashed lines) of different PEM water electrolysis single cells of Example 4.

[0029] Detailed description

[0030] The present disclosure relates to an electrolysis cell 1 comprising: an anode compartment 2 comprising an anode pole plate 3; optionally an anode flow field 4; an electrically conducting anode porous transport layer 5; and an anode catalyst layer 6; a membrane 7; a cathode compartment 8 comprising a cathode pole plate 9; optionally a cathode flow field 10; an electrically conducting cathode porous transport layer 11; and a cathode catalyst layer 12; wherein the membrane 7 separates the cathode compartment 8 from the anode compartment 2; and wherein the anode compartment 2 and the cathode compartment 8 are configured to be supplied with a fluid; and wherein at least one of the electrically conducting anode porous transport layer 5 or the electrically conducting cathode porous transport layer 11 is composed of at least one metallic support layer I in the form of a three-dimensional open porous structure; and at least one macroporous layer II deposited on the at least one metallic support layer I wherein the at least one macroporous layer II comprises titanium particles III; characterized in that the titanium particles III are at least partly covered with at least one conductive titanium suboxide surface layer IV comprising TiOxand / or TisO and wherein x is 0.7-1.3.

[0031] According to the present disclosure, the at least one metallic support layer I is in the form of a three-dimensional open porous structure and these open pores will ensure good mass transport properties as they are interconnected. Further, in the present disclosure, the term “macropores” means pores greater than 50 nanometers.

[0032] It has surprisingly been found that the at least one macroporous layer II will allow electrons to pass through even though there is no complete metallic contact between the individual titanium particles III. Without being bound to any theory, it is believed the conductivity of the titanium suboxide surface layer IV will facilitate the passage. Additionally, the at least one macroporous layer II will increase the total contact area between porous transport layer 5, 11 and catalyst layer 6, 12. The increased contact area will improve the contact point distribution and reduce the contact resistance between porous transport layer 5, 11 and catalyst layer 6, 12 and thereby reduce the ohmic resistance within the electrolysis cell 1. When the present porous transport layer 5 is used in the anode compartment 2, the porous structure will increase the transport of water to the anode catalyst layer 6 due to capillary forces. Further, the porous transport layer 5 will at the same time prevent the formation of large bubbles of oxygen, which would block further water transport to the anode catalyst layer 6. Both of these effects will decrease the mass transport losses and thereby increase the efficiency of the electrolysis cell 1.

[0033] According to embodiments, the electrically conductive anode porous transport layer 5 may exactly be the same as the electrically conductive cathode porous transport layer 11. According to embodiments, the electrically conductive anode porous transport layer 6 may be different from the electrically conductive cathode porous transport layer 11. Examples but not limited to differences are; composed of different components; composed of different materials; titanium particles may have different particle sizes; the macroporous layers may have different pore sizes; the metallic support layer may have different structure or be composed of different materials.

[0034] According to embodiments, the titanium particles may be spherical particles or non-spherical particles.

[0035] Examples of but not limited to other suitable porous transport layers to be used if the anode porous transport layer should differ from the cathode porous transport layer are a carbon porous structure (cathode) and a metallic fiber felt, such as stainless steel fiber felt (cathode) or titanium fiber felt (anode).

[0036] According to embodiments, the anode porous transport layer 5 is the porous transport layer with titanium particles partly covered with titanium suboxide as defined hereinabove or hereinafter and the cathode porous transport layer 11 is a carbon porous structure or a stainless fiber felt.

[0037] According to embodiments, the cathode porous transport layer 11 is the porous transport layer with titanium particles partly covered with titanium suboxide as defined hereinabove or hereinafter and the anode porous transport layer 5 is a titanium fiber felt.

[0038] According to embodiments, the at least one conductive titanium suboxide surface layer IV has a content of more than 50 vol% of TiOx. This will enhance the conductivity and ensure even more that the electrons will be able to pass through the porous transport layer 5, 11. As seen in Figure 2, which shows a schematic figure of the porous transport layer 5, 11, the titanium suboxide IV may be present both as covering part or the whole surface of the titanium particles III and in the junction between titanium particles III. According to embodiments, the at least one conductive titanium suboxide surface layer IV has a thickness in the range of 100 nm to 5 pm.

[0039] According to embodiments, the pore size in the at least one macroporous layer II is in the range of 1 to 100 pm as this will ensure sufficient capillary forces. According to embodiments, the porosity of the at least one macroporous layer II is in the range of 10 to 70 vol%. This will ensure that fluid such as water, oxygen, and hydrogen may be transported through the layer.

[0040] According to embodiments, the at least one macroporous layer II has a thickness in the range of 10 to 500 pm. This will ensure that the corrosion protection is sufficient when needed. The thickness of the macroporous layer II may be correlated with the desired pore size and / or particle size of the titanium particles II.

[0041] According to embodiments, there may be more than one macroporous layer and the macroporous layers may be the same or different. Examples but not limited to with what is meant by different are: composed of different particles, meaning that the particles may be of different material; have different particle size, have different structure. According to embodiments, there may be different particle sizes in the same macroporous layer II.

[0042] According to embodiments, the number of macroporous layers II may be from 1 to 20, such as from 1 to 10, such as from 1 to 5.

[0043] According to embodiments, the at least one metallic support layer I may be selected from a group of a wire mesh, an expanded metal, a perforated metal or a combination thereof. According to embodiments, the perforated metal may be a perforated metal sheet wherein the perforations have been obtained through laser cutting or other cutting methods.

[0044] According to embodiments, the pore size of the pores in the at least one metallic support layer I is in the range of 5 pm and 5 mm. The at least one metallic support layer may have the same pore size throughout the layer or may have different pore sizes throughout the layer.

[0045] According to embodiments, the number of metallic support layers may be in the range of 1 to 15, such as 1 to 10, such as 2 to 8, such as 3 to 7.

[0046] In an electrolysis cell 1 , all the components shown in Figure 1 are to be sandwiched between two plates 3, 9, also known as the pole plates. These plates 3, 9 ensure the stability of the cell 1. These pole plates are made from metallic material and may be formed to include a flow field structure on the plate itself or be unformed. The flow field 4, 10 is optional and may be included for example when the plates 3, 9 are unformed, i.e., have a flat structure. The flow field will facilitate the introduction of starting materials and the removal of products.

[0047] According to embodiments, the fluid of the electrolysis cell 1 may be selected from water, an alkali hydroxide liquid or an aqueous containing gas. Example of an alkali hydroxide liquid is NaOH (I) or KOH (I). The aqueous containing gas. i.e., the humidified gas may be humidified air. According to embodiments, the fluid of the anode compartment 2 may be different from the fluid of the cathode compartment 8.

[0048] The present disclosure also relates to a process for manufacturing an electrolysis cell 1 as defined hereinabove or hereinafter, wherein the process comprises the following steps for manufacturing the electrically conductive anode porous transport layer 5 or the electrically conductive cathode porous transport layer 11 :

[0049] Providing at least one metallic support layer I;

[0050] Providing titanium particles III;

[0051] Exposing the titanium particles III to a high velocity atmospheric spraying process whereby at least one macroporous layer II is formed during the deposition of the titanium particles III on the at least one metallic support layer II; wherein the high velocity atmospheric spraying process is performed at a temperature below the melting point of the titanium particles III and in a process atmosphere having a ratio O2:CH4of 0.3 to 0.7 :1.

[0052] The process will provide for the formation of desired titanium suboxides IV. Furthermore, the porous transport layer 5, 11 obtained by the present process will have electron conductivity through the deposited layer II even though there will be no complete metallic contact between the individual titanium particles due to the formation of titanium suboxide IV. Furthermore, the titanium particles III will form macropores in the at least one macroporous layer II. The high velocity atmospheric spraying process is performed until the desired thickness and the desired amount of titanium suboxide IV is formed and the desired thickness of the macroporous layer II has been obtained.

[0053] The present disclosure is described further in the following non-limiting examples.

[0054] Examples

[0055] Example 1 Argon-atomized spherical titanium powder grade 1 with a particle size of D15-45 pm was used. The metallic support layer used was a plate of 316L stainless steel for Samples 1 to 4 and MeliDiff 1500 316L stainless steel - an expanded metal mesh laminate for Sample 5.

[0056] The titanium particles were sprayed on the support layer using a high velocity oxy air fuel (HVOAF) process. The spraying was performed several times to obtain the desired structure.

[0057] The gas mixture used was: air, nitrogen, CH4 (natural gas), and O2. Even though air also contains nitrogen and oxygen, extra amounts of these gases were added to the gas mixture.

[0058] The gas mixture always contained the same amount of air and nitrogen which was 1500 and 80 slpm (standard liters per minute), respectively. The content of O2 and CH4 was varied in the gas mixture by changing their ratio (see Table 1).

[0059] Table 1 The used O2:CH4 ratio

[0060] As can be seen from Figures 3A and 3B and Figures 3E and 3F, a high ratio of C^CF will provide a microstructure which is too dense to allow water and oxygen mass transport in an electrolysis cell with Sample 2 and Sample 1. Additionally, as can be seen from Figure 3C and 3D and Figures 3G and 3H, a low C^CF ratio will provide for a desired macroporous structure (Sample 3 and Sample 4) which will provide an electrolysis cell with desired properties. Sample 3 had a macroporous layer with a thickness in the range of 150-250 pm.

[0061] A polished cross-section of Sample 5 was investigated with SEM / EDS (scanning electron microscopy / energy dispersive spectroscopy) using a Zeiss Sigma VP FEG-SEM instrument equipped with an Oxford EDS detector. Micrographs obtained at a magnification of 250 and 4000 using 10 kV acceleration voltage and a backscatter detector are shown in Figure 4A and 4B. The bright contrast regions in Figure 4B relate to titanium powder particles whereas the dark contrast regions in the particle interfaces show an oxygen rich titanium phase. The thickness range of the titanium suboxide phase was measured in the micrographs to 100 nm - 5 pm.

[0062] The phases of the macroporous layer of Sample 5 were investigated using XRD (X-ray diffraction) using a Bruker D8 Advance diffractometer with a Co Kasource in Gl-mode (1° grazing incidence), a Gdbel mirror and a LynxEye XE Si-strip detector with equatorial Soller slits in front. The resulting diffractogram in Figure 5 showed the presence of titanium suboxides (TiOxand TiaO) but no presence of stochiometric TiC>2. A diffractogram of the titanium particles before the process started showed presence of only titanium phase. Hence, the titanium suboxides formed originated from the HVOAF process. The presence of TiOxand TiaO in the oxygen rich interface between the titanium particles was also verified by EBSD (electron backscatter diffraction).

[0063] Example 2

[0064] The impact of different anode porous transport layers in a PEM water electrolysis (PEMWE) single cell was investigated and the result is shown in Figure 6. The cells tested are shown in Table 2. For the different components and where they are located in the cell see Figure 1. The anode porous transport layer of the cell C was Sample 5 in Example 1 .

[0065] Table 2 Components of tested electrolysis single cells.

[0066] Figure 6 shows the polarization curves of cells A, B and C. In Figure 6, by the term “iR-free” is meant the subtraction of ohmic voltage increase (voltage = current [i] * ohmic resistance [R]); this parameter is used for showing the mass-transport behavior of the cell.

[0067] These measurements show that the polarization curve of cell A has very high potentials at current densities even below 0.25 A cm-2, which is attributed to the corrosion of the Meli Diff 1500 316L due to the high potential at the APTL (5) / ACL (6) interface. This means that in cell A, the stainless steel PTL is not stable and corrodes so fast that an operation of the cell is not possible. In cell B, the PTL at the anode side (5) consists of Meli Diff 1500 Ti and titanium is a material which is corrosion stable at the high potential at the APTL (5) / ACL (6) interface and, thus, a stable polarization curve up to 2 A cm-2was obtained with a cell voltage of 2.2 V. However, the iR-free curve of cell B still shows a considerable slope. This slope is due to unfavorable mass transport properties. The slope is also the reason for the high cell voltage in comparison to cell C.

[0068] Further, Figure 6 shows that cell C exhibits a lower cell voltage at 2 A cm-2than cell B, 1.965 vs. 2.2 V. The iR-free curve of cell C shows that this is mainly due to a better mass transport which is obtained by the presence of the macroporous layer. Additionally, this is shown from the absence of a slope in the iR-free curve at current densities above 0.5 A cm-2in comparison to the iR-free curve of cell B which shows a considerable slope.

[0069] In addition, the ohmic cell resistances of cell B and cell C have been determined from the HFR (high frequency resistance at 1 A cm'2) with 200 and 189 mQ cm2, respectively. This shows that the ohmic cell resistance of cell C is reduced in comparison to cell B. Without being bound to any theory, it is believed that this result is due to the macroporous layer as the cells have the same components except for the APTL (5). Thus, it is very important to select the right components in an electrolysis cell.

[0070] Finally, a comparison of the polarization curves of cell A and cell C show that the stainless- steel component (MeliDiff 1500 316L) is stabilized by the presence of the macroporous layer of spherical titanium particles covered with at least one conductive titanium suboxide surface layer and does not corrode in spite of the high potential at the APTL (5) / ACL (6) interface. This is shown as a stable polarization curve can be recorded at least up to 2 A cm-2. Without being bound to any theory, the low ohmic cell resistance of a sample manufactured as described for Sample 4 and 5, suggests that this porous transport layer can also be used on the cathode side. This is supported by the presence of Ti-suboxide layers which can act as effective barrier layers for hydrogen uptake in the particles.

[0071] Hence, it has been found that by carefully selecting the components for the electrolysis cell, the present electrolysis cell will have low ohmic losses.

[0072] Example 3

[0073] Non-spherical commercially pure titanium powder with <5000 ppm of oxygen and a particle size distribution of 0 < powder size < 45 pm was used. The metallic support layer used was a plate of 316L stainless steel for Samples 6 to 8 and MeliDiff 1500 316L stainless steel - an expanded metal mesh laminate for Sample 9.

[0074] The titanium particles were sprayed on the support layer using a high velocity oxy air fuel (HVOAF) process. The spraying was performed several times to obtain the desired structure. The gas mixture used was: air, nitrogen, CH4 (natural gas), and O2. Even though air also contains nitrogen and oxygen, extra amounts of these gases were added to the gas mixture.

[0075] The gas mixture always contained the same amount of air and nitrogen which was 1500 and 80 slpm (standard liters per minute), respectively. The content of O2 and CH4 was varied in the gas mixture by changing their ratio (see Table 3).

[0076] Table 3 The used C>2:CH4 ratio

[0077] As can be seen from Figure 7A, a high ratio of O2:CH4 used for Sample 6 will provide a microstructure which is too dense to allow water and oxygen mass transport in an electrolysis cell. Additionally, as can be seen from Figure 7B and 7C, a low C^CF ratio will provide for a desired macroporous structure (Sample 7 and Sample 8) which will provide an electrolysis cell with desired properties. Sample 6, Sample 7 and Sample 8 had a macroporous layer with a thickness in the range of 100-150 pm.

[0078] A polished cross-section of Sample 9 was investigated with SEM / EDS (scanning electron microscopy / energy dispersive spectroscopy) using a Zeiss Sigma VP FEG-SEM instrument equipped with an Oxford EDS detector. Micrographs obtained at a magnification of 200 and 2000 using 10 kV acceleration voltage and a backscatter detector are shown in Figure 8A and 8B. Similar as for Sample 5 in Figure 4B, the dark contrast regions in Figure 8A and Figure 8B located in the particle interfaces show an oxygen rich titanium phase. The thickness range of the titanium suboxide phase was measured in the micrographs to 200 nm - 6 pm.

[0079] The phases of the macroporous layer of Sample 9 were investigated using XRD (X-ray diffraction) using a Bruker D8 Advance diffractometer with a Co Kasource in Gl-mode (1° grazing incidence), a Gdbel mirror and a LynxEye XE Si-strip detector with equatorial Soller slits in front. The resulting diffractogram in Figure 9 showed the presence of titanium suboxides (TiOxand TiaO) but no presence of stochiometric TiO2. A diffractogram of the titanium particles before the process started showed presence of only titanium phase. Hence, the titanium suboxides formed originated from the HVOAF process. The presence of TiOxand TiaO in the oxygen rich interface between the titanium particles was also verified by EBSD (electron backscatter diffraction). Example 4

[0080] The performance in a PEM water electrolysis (PEMWE) single cell of an anode porous transport layer coated with non-spherical titanium particles was investigated and the result is shown in Figure 10. The cell tested is shown in Table 4. For the different components and where they are located in the cell see Figure 1. The anode porous transport layer of the cell D was Sample 9 in Example 3.

[0081] Table 4 Components of tested electrolysis single cell.

[0082] Figure 10 shows the polarization curve of cell D. In Figure 10, by the term “iR-free” is meant the subtraction of ohmic voltage increase (voltage = current [i] * ohmic resistance [R]); this parameter is used for showing the mass-transport behavior of the cell.

[0083] Figure 10 shows that cell D exhibits a cell voltage of 1.920 V at A cm-2which is lower than the cell voltage for cell C in Example 2. In addition, the ohmic cell resistance of cell D has been determined from the HFR (high frequency resistance at 1 A cm-2) to 166 mO cm2which is also lower than the ohmic cell resistance for cell C in Example 2. Without being bound to any theory, it is believed that this result is due to the higher surface area of the non-spherical titanium powder particles in cell D as the cells have the same components except for the APTL (5).

[0084] The stable polarization curve at least up to 2 A cm-2shows that the stainless-steel component (MeliDiff 1500 316L) is stabilized by the presence of the macroporous layer of the non-spherical titanium particles covered with at least one conductive titanium suboxide surface layer and does not corrode in spite of the high potential at the APTL (5) / ACL (6) interface. Without being bound to any theory, the low ohmic cell resistance of a sample manufactured as described for Sample 4 and 5, suggests that this porous transport layer can also be used on the cathode side. This is supported by the presence of Ti-suboxide layers which can act as effective barrier layers for hydrogen uptake in the particles.

[0085] Hence, it has been found that by carefully selecting the components for the electrolysis cell, the present electrolysis cell will have low ohmic losses.

Claims

Claims1. An electrolysis cell (1) comprising: an anode compartment (2) comprising an anode pole plate (3); optionally an anode flow field (4); an electrically conducting anode porous transport layer (5); and an anode catalyst layer (6); a membrane (7); a cathode compartment (8) comprising a cathode pole plate (9); optionally a cathode flow field (10); an electrically conducting cathode porous transport layer (11); and a cathode catalyst layer (12); wherein the membrane (7) separates the cathode compartment (8) from the anode compartment (2); and wherein the anode compartment (2) and the cathode compartment (8) are configured to be supplied with a fluid; and wherein at least one of the electrically conducting anode porous transport layer(5) or the electrically conducting cathode porous transport layer (11) is composed of at least one metallic support layer (I) in the form of a three-dimensional open porous structure; and at least one macroporous layer (II) deposited on the at least one metallic support layer (I) wherein the at least one macroporous layer (II) comprises titanium particles (III); characterized in that the titanium particles (III) are at least partly covered with at least one conductive titanium suboxide surface layer (IV) comprising TiOxand / or T13O and wherein x is 0.7-1.3.

2. The electrolysis cell (1) according to claim 1 , wherein the fluid is selected from water, an alkali hydroxide liquid or an aqueous containing gas.

3. The electrolysis cell (1) according to claim 2, wherein the fluid of the anode compartment (2) is different from the fluid of the cathode compartment (8).

4. The electrolysis cell (1) according to any one of claims 1 to 3, wherein the electrically conductive anode porous transport layer (5) is the same as the electrically conductive cathode porous transport layer (11).

5. The electrolysis cell (1) according to any one of claims 1 to 3, wherein the electrically conductive anode porous transport layer (5) is different from the electrically conductive cathode porous transport layer (11).

6. The electrolysis cell (1) according to any one of claims 1 to 5, wherein conductive titanium suboxide surface layer (IV) has a content of more than 50 vol% of TiOx.

7. The electrolysis cell (1) according to any one of claims 1 to 6, wherein the at least one conductive titanium suboxide surface layer (IV) has a thickness in the range of 100 nm to 5 pm.

8. The electrolysis cell (1) according to any one of claims 1 to 7, wherein the pore size in the at least one macroporous layer (II) is in the range of 1 to 100 pm.

9. The electrolysis cell (1) according to any one of claims 1 to 8, wherein the porosity of the at least one macroporous layer (II) is in the range of 10 to 70 vol%.

10. The electrolysis cell (1) according to any one of claims 1 to 9, wherein the at least one macroporous layer (II) has a thickness in the range of 10 to 500 pm.

11. The electrolysis cell (1) according to any one of claims 1 to 10, wherein the at least one metallic support layer (I) is selected from the group of a wire mesh, an expanded metal, a perforated metal or a combination thereof.

12. The electrolysis cell (1) according to any one of claims 1 to 11, wherein the pore size in the at least one metallic support layer (I) is in the range of 5 pm and 5 mm.

13. An electrolysis cell stack containing at least one electrolysis cell (1) according to any one of claims 1 to 12.

14. The electrolysis cell stack according to claim 13, wherein the electrolysis cell stack is a proton exchange membrane water electrolyser or an anion exchange membrane water electrolyser.

15. A process for manufacturing an electrolysis cell (1) according to any one of claims 1 to13, wherein a method for manufacturing the electrically conductive anode porous transport layer (5) or the electrically conductive cathode porous transport layer (11) comprises the steps of: - Providing at least one metallic support layer (I);Providing titanium particles (III);Exposing the titanium particles (III) to a high velocity atmospheric spraying process whereby the at least one macroporous layer (II) is formed during the deposition of the titanium particles on the at least one metallic support layer (I); wherein the high velocity atmospheric spraying process is performed at a temperature below the melting point of the titanium particles (III) and wherein the process atmosphere has C>2:CH4 ratio of 0.3 to 0.7 :1.

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