Laminated piece, assembly and electrochemical equipment

Abstract

The present invention relates to a laminate having a plurality of perforated layers, each perforated layer having a two-dimensional periodic structure of openings, where the openings have different sizes. The invention further relates to an assembly comprising a bipolar plate and a laminate according to the invention, and to an electrochemical device comprising a laminate or an assembly according to the invention.

Description

[0001] This application claims priority to European Patent Application No. EP23217083.7, filed with the European Patent Office on December 15, 2023, with the invention title "POROUS TRANSPORT MULTILAYERS", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present invention relates to a laminate having a plurality of perforated layers, each perforated layer having an open two-dimensional periodic structure, wherein the openings have different sizes. Furthermore, the present invention relates to an assembly comprising a bipolar plate and a laminate according to the present invention, and to an electrochemical device comprising a laminate or an assembly according to the present invention. BACKGROUND ART

[0003] In recent years, proton exchange membrane water electrolyzer (PEMWE) systems are emerging as a very promising alternative for the efficient production of green hydrogen (using renewable energy). However, the high content of precious metals such as Ir and Pt required for the electrochemical reactions in PEMWE limits the market penetration and scalability of this technology. Existing technology PEMWE requires approximately 300 kg of Ir per GW of installed system, which is equivalent to an active area loading of approximately 1.5 mg Ir / cm2. Considering that the global production of Ir in 2020 was approximately 8 metric tons, the practical limit of the annual installed capacity would be less than 10 GW. The current efforts of the scientific community are focused on alternative oxygen evolution catalysts (OERs) that can withstand the extreme oxidation conditions at the anode chamber of PEMWE. However, the latest publications in the scientific literature show that the utilization rate of Ir catalysts in existing technology PEMWE is less than 5%, which means that by appropriately optimizing the catalyst layer and its interface with the porous transport layer (PTL), the content of Ir can be reduced by 20 times without affecting the performance or durability of the cell stack.

[0004] There are several drawbacks in the technologies of existing PEMWE and PEM fuel cells (PEMFC). That is, the Ir content should be reduced to less than 0.5 mg / cm2, the stack performance should be improved by reducing the interfacial ohmic resistance, the mechanical stability of the membrane should be enhanced and a thinner membrane should be allowed; furthermore, the total cost of the stack should be reduced by eliminating the need for a protective coating on the anode side of the bipolar plate (BPP) or by reducing the cost of the anode PTL components. However, so far, there are not enough solutions available to address the said drawbacks.

[0005] Therefore, the potential technical problem of the present invention is to provide a method for solving the current drawbacks existing in existing PEMWE.

[0006] The solution to the above technical problem is achieved by the embodiments characterized in the claims. SUMMARY OF THE INVENTION

[0007] The present invention relates to a laminate, comprising: a first perforated layer (11) and a second perforated layer (12) on the first perforated layer (11), wherein each of the first perforated layer (11) and the second perforated layer (12) has an open two-dimensional periodic structure, and

[0008] a first thickness (T1), a first maximum opening size (D1), and a first opening distance (S1) of the first perforated layer (11), and a second maximum opening size (D2) and a second opening distance (S2) of the second perforated layer (12) satisfy the following inequalities (I-1) to (I-5),

[0009] D1≥T1 (I-1);

[0010] D1≥S2 (I-2);

[0011] S1≤(2 / 3)×D1(I-3);

[0012] D2≥5×D1(I-4); and

[0013] S2≤(1 / 3)×D2(I-5).

[0014] Based on the same inventive concept, the present invention also relates to a component, comprising: a bipolar plate and the above laminate on the bipolar plate, wherein the perforated layer opposite to the first perforated layer contacts the bipolar plate.

[0015] Based on the same inventive concept, the present invention also relates to an electrochemical device, comprising: the above laminate or the above component.

[0016] By using the present invention, a laminate with perforated layers that can balance the requirements of the PTL / BPP interface and the PTL / CL interface can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic cross-section of a single-cell PEMWE;

[0018] Figure 2 Schematic cross-section of a typical bipolar plate, which indicates the main parameters defining the geometry of the flow field, such as channel width, platform width, and channel depth;

[0019] Figure 3 Schematic of two different two-dimensional titanium-based porous plates PTL with the same bipolar plate; in the left figure, the opening diameter of the porous plate is 100 μm and the porosity is 40%; in the right figure, the opening diameter of the porous plate is 300 μm and the porosity is 60%;

[0020] Figure 4Top view showing the distribution of activation regions at the interface between a schematic two-dimensional porous plate and a catalyst layer;

[0021] Figure 5 The left figure in the middle shows a three-dimensional schematic of a PTL and a bipolar plate with a double-layer two-dimensional porous plate; the right figure shows a partial high-magnification of the left figure;

[0022] Figure 6 Cross-section of a single PTL / BPP component integrated by resistance welding; note that in this exemplary illustration, two layers of PTL are selected to match the platform and channel dimensions of the BPP;

[0023] Figure 7 Cross-sectional illustrations of two different PTL top layers in direct contact with the catalyst layer; the left figure shows that a thick top layer causes gas accumulation and blockage of openings; the right figure: a thin top layer facilitates the diffusion of gas and water;

[0024] Figure 8 The left figure in the middle shows the detailed geometry of the first perforated layer in a PTL with multiple layers of two-dimensional porous plates; the right figure shows a cross-sectional sketch of a PTL with three layers of two-dimensional porous plates and its main geometric dimensions;

[0025] Figure 9 and Figure 10 Schematic of a laminate where the long opening direction of the bottom layer is perpendicular to the long opening direction of the middle layer. Detailed Description of the Invention

[0026] Figure 1 The cross-section of a single-cell PEMWE is shown. One of the main problems of PEMWE technology is the extreme oxidation conditions that occur at the anode. The typical half-potential at the anode varies from 1.5 V to 1.9 V. Additionally, the presence of a high concentration of O2 in the solution causes very strong anodic oxidation and the formation of non-conductive oxides, unless a protective coating of a noble metal is used. For this reason, the BPP is typically coated with Pt or Au, while the anode PTL is typically coated with Pt or Ir because Au is prone to dissolution when in direct contact with the anode catalyst layer.

[0027] The PTL is a key component that serves several functions, such as acting as an electron collector, a water and gas diffusion medium, and providing mechanical stability to the membrane electrode. The mechanical function is related to the relative operating pressure at both electrodes. Commercial PEMWEs can operate at a pressure difference of 20 or 30 bar at the cathode, which is commonly used for demonstration units. However, two main types of commercial PTLs can be found in PEMWE systems, namely titanium porous plates prepared by sintering titanium powder and titanium felts sintered from titanium fibers. The higher open porosity (57% to 70%) of the titanium felt makes it a preferred choice, especially with better performance at higher current densities. The typical size of the titanium fibers is 20 μm to 50 μm in diameter and up to 1000 μm in length. However, the random orientation characteristics of the titanium felt result in very poor control of the interfacial properties between it and the catalyst layer. The mechanical properties of Nafion membranes and enhanced Nafion-based membranes must be sufficient to withstand the operating pressure (up to 30 bar), and they are prone to deformation and puncture. Here, the geometry of the PTL plays a very important role because large holes with diameters of several hundred micrometers can be found randomly distributed along the surface. This problem is particularly important when the thickness of the membrane is much lower than the maximum pore diameter. Ideally, the open porosity of the PTL should prevent the membrane from deforming excessively under high-pressure operation. However, the inherent random fiber orientation and distribution in the titanium felt make it very complicated to safely use thinner membranes.

[0028] To avoid battery degradation due to the oxidation of titanium components, the PTL is usually coated with 200 nm to 400 nm of Pt or Ir, i.e., a protective coating is required at the interfaces of BPP / PTL and PTL / catalyst layer. However, due to the characteristics of porous components, in actual operation, it is common for Pt or Ir to cover areas that do not participate in the electron transport phenomenon, such as the main body of the PTL. This waste can account for up to 70% to 80% of the total amount of precious metals used in the process, which is an important source of the increased cost of the PTL. Although some deposition processes using "rays", such as magnetron sputtering, can reduce the waste of Pt to a certain extent, the durability of such coatings still needs to be studied in depth.

[0029] The conductivity of the catalyst layer (CL) on both sides of the proton exchange membrane is several orders of magnitude lower than that of titanium. Experimental data shows that the regions in the CL layer that are not in direct contact with the PTL do not actively participate in the electrochemical reaction. The low intrinsic conductivity of the CL results in lower in-plane electron transport, so measures must be taken to improve the catalyst utilization rate. The typical thickness of the anode catalyst layer is 5 - 9 μm, and the typical diameter of the titanium fibers used in commercial titanium felts ranges from 20 μm to 50 μm. During battery assembly and use, the membrane and CL will deform, resulting in more regions of inactive catalyst. As mentioned above, the regions in the CL far from the vicinity of the titanium fibers are electrically insulating. At the same time, the regions in the CL in direct contact with the center of the titanium fibers have limited contact with the reactant (water), and the oxygen generated by the electrochemical reaction cannot be efficiently transferred. Many related studies are underway to explore different ways to enhance the PTL / CL interface by adding a microporous layer (MPL). This microporous layer (MPL) acts as a buffer region, with a thickness of 20 μm to 50 μm, a small pore diameter (5 μm to 10 μm), and a high porosity (up to 40%). However, such a strategy shows relatively small improvements in performance but results in higher material and process costs.

[0030] In the past decade, the interface between the PTL and the BPP in PEMWE has been studied in detail. In an unprotected state, the titanium-based BPP forms a passivation oxide layer over time (most obvious within the first 24 hours of operation and continuing to grow for thousands of hours), which results in a single-cell overpotential of up to 60 mV. This 60 mV single-cell overpotential is equivalent to a decrease in the efficiency of the PEMWE stack of approximately 10% during its lifetime. When coated with a Pt plating, the average resistance of the PTL / BPP interface is 5 mΩ to 10 mΩ and remains stable during long-term operation. In addition to conductivity, thermal conductivity plays an important role in the in-plane current distribution of the catalyst layer. Therefore, another important parameter to consider is the thermal conductivity at the PTL / BPP interface. Thus, the bipolar plate requires an expensive Pt coating to keep the ohmic resistance at the interface below 10 mΩ, which leads to an increase in the cost of the BPP. In some cases, the increased plating cost even exceeds the cost of the BPP itself.

[0031] In addition to the above limitations, manufacturing sintered titanium felts is a high-energy-consuming and slow process, with multiple steps and special atmosphere conditions to prevent oxidation. The cost contribution of the anode PTL to the total cost of the PEMWE stack is between 15% and 22%, second only to the membrane electrode (CCM) with a cost contribution of 40% to 47%, making it the second most expensive component in the PEMWE stack.

[0032] In summary, the existing titanium-based PTL technology used in PEMWE is not optimized for the demanding requirements. Therefore, alternative solutions based on simpler and sintering-free processes are needed to reduce the cost of PEMWE stacks, as well as the noble metal content in the anode catalyst layer and BPP.

[0033] One of the latest developments in PTL technology involves changing from a three-dimensional porous structure (such as titanium felt) to a two-dimensional design of a simpler perforated titanium sheet. Electrochemical results show that the overpotential is reduced by 100 mV when compared with the existing PTL based on sintered titanium fibers. However, in an actual PEMWE system, there are several problems with the above concept. For example, the manufacturing process involves complex lithography steps and subsequent hydrofluoric acid etching, which leads to serious chemical waste treatment. Additionally, it is a relatively slow process. Moreover, the resulting perforated sheet is very fragile and difficult to handle without breaking. The inherent mechanical instability makes this PTL concept inapplicable to cells operating under differential pressure conditions. Since the lateral diffusion of water and gas at the interface PTL / BPP is very low, the flow field geometry of the bipolar plate is very restricted. The surface of the two-dimensional titanium sheet is very flat and has low hydrophilicity, which results in lower diffusion efficiency of water and oxygen.

[0034] Therefore, the potential technical problem of the present invention is to provide a method for solving the current drawbacks existing in the prior art PEMWE.

[0035] In particular, the present invention relates to a laminate, comprising: a first perforated layer (11) and a second perforated layer (12) on the first perforated layer (11), wherein each of the first perforated layer (11) and the second perforated layer (12) has an open two-dimensional periodic structure, and

[0036] the first thickness (T1), the first maximum opening size (D1), and the first opening distance (S1) of the first perforated layer (11), and the second maximum opening size (D2) and the second opening distance (S2) of the second perforated layer (12) satisfy the following inequalities (I-1) to (I-5),

[0037] D1≥T1 (I-1);

[0038] D1≥S2 (I-2);

[0039] S1≤(2 / 3)×D1(I-3);

[0040] D2≥5×D1(I-4); and

[0041] S2≤(1 / 3)×D2(I-5).

[0042] Using the present invention, a laminate with a perforated layer can be provided that can balance the requirements of the PTL / BPP interface and the PTL / CL interface. One of the fundamentally different characteristics between a PEM electrolyzer and a PEM fuel cell is the nature of the electrochemical reactants. For a fuel cell, both the reactants and the products are in the same gas phase (although water condensation may occur in the anode chamber), but the products in a water electrolyzer are gases (O2 and H2), while the reactant is liquid water. This mixing of the liquid and gas is particularly important in the anode chamber, where water molecules must reach the catalytic sites efficiently. As a two-phase system, the bipolar plates in a PEM electrolyzer require special attention to the geometry of the flow field and design features. Figure 2 The image of Figure 2 shows a cross-section of a typical bipolar plate, which indicates the main parameters defining the geometry of the flow field.

[0043] The three most important dimensions for the fluid distribution in the flow field that affect cell performance and durability are the channel depth, the channel width, and the land width. Due to the poor contact between the PTL and the CL, a large channel width of more than 2 mm may have a negative impact on performance. At the same time, the channel depth and the channel cross-sectional area affect the hydrodynamics and bubble enrichment. Given that the PTL is located between the CL and the BPP, the land width also affects the lateral diffusion of gases and liquids. For this reason, a large land width will require a thicker PTL with a very high open porosity to enhance the lateral flow. Therefore, when aiming to use the entire surface of the catalyst layer, a very short land width will be required. Figure 3 This is further clarified. It should be noted that in the present invention, the PTL refers to a device having one or more layers of porous structure (i.e., the PTL is a laminate), and a single layer structure included therein can be called a two-dimensional porous plate (or a two-dimensional perforated layer, or a perforated layer).

[0044] For a two-dimensional porous plate with small openings having a diameter of about 100 μm and a BPP with a land width of 1.5 mm as shown in the left part of Figure 3 , since there is almost no lateral diffusion between the BPP and the PTL, about 30% of the openings are blocked by water. When the diameter of the openings is increased to 300 μm or 400 μm (as shown in the right part of Figure 3 ), the lateral diffusion is improved, but the contact area between the PTL and the CL is sacrificed. The active contact area is a key parameter that determines the efficiency of the process and enables an increase in catalyst utilization.

[0045] The catalyst layer at the anode mainly consists of two different components. Ir or IrO2 nanopowders with an average size of 10 nm to 20 nm act as catalysts and also serve as electron conduction paths. Nafion dispersions are polymer aggregates with sizes up to 500 nm, which act as binders and proton conductive media. Additionally, porosity is a very important part of the catalyst layer that enables mass transfer. The ratio between the catalyst, polymer, and porosity will determine the efficiency of the reaction. The typical range of the in-plane electron resistance in the anode CL is from 100 Ω to 1000 Ω. This lateral resistance to electron flow has a direct impact on the catalyst utilization within the CL. Several studies have attempted to address the complex task of measuring the active area of the catalyst layer, and it can be concluded that the electron flow can extend up to 10 μm in the lateral direction directly contacting the titanium-based PTL. To clarify the meaning of such a low electrical conductivity of the catalyst layer, reference can be made to the Figure 10 (see "Electrochimica Acta" 255 (2017) 405 - 416). The Figure 10 b, Figure 10 c, Figure 10 d, and Figure 10 e represent two-dimensional porous plates with a diameter of 50 μm, which are in direct contact with the catalyst layer and have in-plane resistivities of 1.52*10 -2 Ω*m, 1.52*10 -3 Ω*m, 1.52*10 -4 Ω*m, and 1.52*10 -5 Ω*m, respectively. When the cell is subjected to a current density of 2 A / cm 2 , the current distribution in each case is shown in red. The in-plane electrical conductivity of the commercial catalyst layer will be closer to the cases presented in Figure 10 c and Figure 10 d of the above-mentioned publication, where most of the CL regions not in contact with the two-dimensional porous plate remain inactive, resulting in a very low catalyst utilization. To clarify what is considered an active contact area, reference is made to Figure 4 , which shows a unit cell with a two-dimensional porous plate, indicating the regions contributing to current generation. Three main regions can be distinguished, where the catalyst activity will depend on the diffusion rates of oxygen and water between the CL and the PTL. Those regions far from the opening edges can be considered inert or completely blocked to water and gas. Then, within a range of 20 μm or 30 μm around each opening, there will be limited diffusion rates of reactants and products. Finally, the active contact area can be defined as the surface of the PTL that is in direct contact with the CL and also in full contact with the reactants. Since there are solids, gases, and liquids, this is also called the triple-phase boundary (TPB).

[0046] As described herein, by reducing the pore size and porosity of the PTL at the PTL / CL interface, the active contact area of the CL can be increased or even maximized. In contrast, for the PTL / BPP interface, the lateral diffusion of gas and water at the BPP / PTL interface can be increased or even maximized by optimizing the PTL parameters through increasing the pore size and porosity of the PTL at the BPP / PTL interface. In the present invention, a plurality of two-dimensional perforated layers of defined size are stacked to obtain the PTL (laminate), which enables the requirements of the PTL / BPP interface to be balanced with the requirements of the PTL / CL interface.

[0047] Figure 5 An exemplary laminate having two perforated layers is depicted. The laminate or multi-layer PTL includes a top layer (which will be in direct contact with the catalyst layer) having a porosity of 50% and an average opening diameter of 100 μm, and a bottom layer having a porosity of 70% and an average opening diameter of 500 μm. In Figure 5 To the right is an enlargement of the same multi-layer PTL, where the distribution of the openings can be estimated. Continuing with the above example, Figure 6 The cross-sectional sketch depicted in is used as an example of a preferred PTL design for a given BPP, where the flow field is determined by a platform width of 1.5 mm and a channel width of 1.5 mm. From Figure 6 it can be readily estimated that most of the small openings in the top layer should respectively contribute to the dynamic distribution of water and oxygen from and to the channels.

[0048] Furthermore, the laminate of the present invention has high mechanical stability. As described above, PEMWE systems typically operate under a pressure difference (exceeding 20 bar). Therefore, in view of the fact that even a small pressure deviation may cause permanent deformation and premature failure of the PEMWE stack, it is necessary to consider the mechanical requirements of the PTL. Although it is possible to consider increasing the thickness of the perforated layer in direct contact with the CL, an excessive thickness of the same layer may lead to gas accumulation and cause clogging of the openings. Figure 7 Shows the possible effect of layer thickness on gas removal.

[0049] According to the present invention, the laminate includes a first perforated layer (11) and a second perforated layer (12) on the first perforated layer (11). The term "laminate" herein means that a plurality of perforated layers are stacked on top of each other and tend to be physically bonded by welding (such as diffusion welding or resistance welding) to form a single integrated component. The optimized laminate contains at least two two-dimensional perforated layers, which can be 2 to 6, preferably 2 to 4, more preferably 2 or 3.

[0050] The term "opening" as used herein means that the perforated layer opens from one major surface to the other opposite major surface of the corresponding perforated layer through the opening. Thus, the opening can also be considered as a through-hole between the major surfaces of the perforated layer. For example, in Figures 3 to 10 corresponding openings are depicted. The shape of the opening is not particularly limited. For example, the shape of the opening can be circular, oval, triangular, rectangular, square rhombus, or can have a two-dimensional shape of other polygons. Between the perforated layers, the shapes of the openings can be the same or different. For example, the first perforated layer can have one opening shape, preferably circular, and the second perforated layer and any additional perforated layers can have the same opening shape or another opening shape, for example, each being a rhombus shape, with different dimensions.

[0051] The term "two-dimensional periodic structure of the openings" as used herein means that the openings form a periodic structure extending two-dimensionally perpendicular to the thickness direction of the perforated layer. For example, in Figure 3 , Figure 5 , Figure 9 and Figure 10 corresponding structures are depicted. The perforated layers have different two-dimensional periodic structures of the openings.

[0052] Each perforated layer in the perforated layers has a thickness (T), a maximum opening size (D), an opening distance (S), and an opening porosity (O). The thickness (T) extends between the two major surfaces of the corresponding perforated layer. The maximum opening size corresponds to the maximum size (e.g., maximum diameter) of the opening of the corresponding perforated layer. For an opening having a single diameter, such as circular, the diameter corresponds to the maximum opening size (D). Openings having different shapes (such as rhombus or oval) have different diameters. In this case, the maximum opening size (D) corresponds to the maximum size / diameter of the opening. The minimum opening size (Dmin) corresponds to the minimum size / diameter of the opening. The opening distance (S) corresponds to the average distance between adjacent openings. The opening porosity (O) is defined as the ratio of the apparent area of the opening to the apparent area of the perforated layer. Figures 8 to 10 Schematically shows the geometries of different perforated layers in an exemplary three-layer laminate.

[0053] In the case where two or more perforated layers have openings of different sizes, the two-dimensional periodic structures of the corresponding openings can be arranged such that the maximum opening sizes are arranged in any possible manner, preferably arranged parallel or perpendicular to each other. Preferably, the maximum opening sizes are arranged perpendicular to each other. Figure 9 and Figure 10The corresponding exemplary arrangement is depicted, wherein the maximum opening size of the bottom layer is perpendicular to the maximum opening size of the intermediate layer. When assembled with the BPP, the maximum opening size of the bottom layer is preferably perpendicular to the BPP platform and the channels (extending direction), while the maximum opening size of the intermediate layer is preferably parallel to the BPP platform and the channels (extending direction).

[0054] According to the present invention, the first thickness (T1), the first maximum opening size (D1), and the first opening distance (S1) of the first perforated layer (11), and the second maximum opening size (D2) and the second opening distance (S2) of the second perforated layer (12) satisfy the following inequalities (I-1) to (I-5):

[0055] D1≥T1 (I-1);

[0056] D1≥S2 (I-2);

[0057] S1≤(2 / 3)×D1(I-3);

[0058] D2≥5×D1(I-4); and

[0059] S2≤(1 / 3)×D2(I-5).

[0060] In addition to the first perforated layer (11) and the second perforated layer (12), the laminate may further include additional perforated layers. For example, the laminate may further include a third perforated layer (13) on the second perforated layer (12), wherein the third perforated layer (13) has a two-dimensional periodic structure of openings, and the second maximum opening size (D2) of the second perforated layer (12), the third maximum opening size (D3) of the third perforated layer (13), and the third opening distance (S3) satisfy the following inequalities (I-6) to (I-8):

[0061] D2≥3×S3(I-6);

[0062] S3≤(1 / 4)×D3(I-7); and

[0063] D3≥1.5×D2(I-8).

[0064] The laminate may include more than three perforated layers, wherein the additional perforated layers are successively disposed on the third perforated layer. Each of the additional perforated layers has a two-dimensional periodic structure of openings, wherein the following inequalities (I-9) to (I-11) are satisfied:

[0065] D(n-1)≥3×Sn(I-9);

[0066] Sn≤(1 / 4)×Dn(I-10); and

[0067] Dn ≥ 1.5 × D(n - 1)(I - 11).

[0068] In the above inequality, n represents the total number of perforated layers, D(n - 1) represents the maximum opening size of the (n - 1)th perforated layer, Dn represents the maximum opening size of the nth perforated layer, and Sn represents the opening distance of the nth perforated layer.

[0069] The first thickness (T1) of the first perforated layer (11) can range from 25 μm to 200 μm, preferably from 50 μm to 100 μm. The second thickness (T2) of the second perforated layer (12) can range from 50 μm to 250 μm, preferably from 100 μm to 200 μm. In the case where the laminate includes three or more perforated layers, the third thickness (T3) of the third perforated layer (13) can range from 100 μm to 500 μm, preferably from 150 μm to 300 μm. The thicknesses of the optional additional perforated layers can each independently range from 100 μm to 500 μm, preferably from 150 μm to 300 μm. The third perforated layer is not thinner than the second perforated layer. The total thickness of the laminate is preferably at least 200 μm.

[0070] The first perforated layer (11) can have a first open porosity (O1) ranging from 30% to 70%, preferably from 40% to 60%. The second perforated layer (12) can have a second open porosity (O2) ranging from 50% to 90%, preferably from 60% to 80%. In the case where the laminate includes three or more perforated layers, the third perforated layer (13) can have a third open porosity (O3) ranging from 60% to 90%, preferably from 70% to 80%. The open porosities of the optional additional perforated layers can each independently range from 70% to 90%, preferably in the range from 80% to 90%. Preferably, the open porosity increases from the first perforated layer to the associated perforated layer.

[0071] The first maximum opening size (D1) of the first perforated layer (11) can be selected from the range of 30 μm to 300 μm, preferably from 50 μm to 200 μm, and most preferably from 70 μm to 140 μm. The second maximum opening size (D2) of the second perforated layer (12) can be selected from the range of 400 μm to 1500 μm, preferably from 500 μm to 1000 μm, and most preferably from 550 μm to 700 μm. In the case where the laminate includes three or more perforated layers, the third maximum opening size (D3) of the third perforated layer (13) can be selected from the range of 600 μm to 2300 μm, preferably from 900 μm to 1500 μm. The maximum opening sizes of the optional additional perforated layers can each independently be selected from the range of 600 μm to 2300 μm, preferably from 900 μm to 1500 μm. Preferably, the maximum opening size increases from the first perforated layer to the opposite perforated layer.

[0072] In the case where the sizes of the openings are non-uniform, the first minimum opening size (Dmin1) of the first perforated layer (11) can be selected in the range from 15 μm to 150 μm, preferably from 20 μm to 90 μm, and most preferably from 30 μm to 60 μm. The second minimum opening size (Dmin2) of the second perforated layer (12) can be selected in the range from 200 μm to 550 μm, preferably from 300 μm to 500 μm, and most preferably from 350 μm to 450 μm. In the case where the laminate includes three or more perforated layers, the third minimum opening size (Dmin3) of the third perforated layer (13) can be selected in the range from 400 μm to 1200 μm, preferably from 500 μm to 1100 μm, and most preferably from 600 μm to 1000 μm. The minimum opening sizes of the optional additional perforated layers can be independently selected in the range from 400 μm to 1200 μm, preferably from 500 μm to 1100 μm, and most preferably from 600 μm to 1100 μm.

[0073] The first opening distance (S1) of the first perforated layer (11) can be selected in the range from 20 μm to 100 μm, preferably from 50 μm to 80 μm, and most preferably from 60 μm to 70 μm. The second opening distance (S2) of the second perforated layer (12) can be selected in the range from 30 μm to 120 μm, preferably from 85 μm to 115 μm, and most preferably from 90 μm to 110 μm. In the case where the laminate includes three or more perforated layers, the third opening distance (S3) of the third perforated layer (13) can be from 100 μm to 500 μm, preferably from 140 μm to 350 μm. The opening distances of the optional additional perforated layers can be independently selected in the range from 100 μm to 500 μm, preferably from 140 μm to 350 μm.

[0074] The perforated layer can be, for example, a perforated titanium sheet, a perforated stainless steel sheet, and a perforated nickel-based sheet. The perforated layer is preferably a perforated titanium sheet. The methods for preparing the corresponding perforated layers are known in the art. For example, the perforated layer can be prepared by photolithography, etching, stamping, expansion sheet processing, and laser micro-perforation. Different perforated layers can be manufactured by different methods. For example, the first perforated layer can be obtained by laser perforation or laser drilling, and the other perforated layers can be obtained by laser perforation, laser drilling, or expansion sheet processing.

[0075] The perforated layer can be further processed as needed. For example, the perforated layer can be surface-treated, for example, by providing an antioxidant protection coating on the first perforated layer and the perforated layer associated with the first perforated layer, preferably, if possible, only on the first perforated layer, to surface-treat the perforated layer.

[0076] Each layer can be connected, for example, by bonding or welding. It is preferred to reduce the physical interface so that the resistance between the perforated layers is the same as that of the titanium body, making the conductivity of the entire laminate similar to that of the titanium body. Processes such as resistance welding or diffusion welding are preferred.

[0077] Another aspect of the present invention relates to a method for producing the laminate of the present invention. The above definitions and embodiments equally apply to this aspect of the present invention. The following definitions and embodiments equally apply to other aspects of the present invention.

[0078] For example, the method can involve: the step of providing at least two perforated layers (i.e., at least a first perforated layer and a second perforated layer and optionally additional perforated layers), and the step of combining different layers by stacking and welding. The methods for providing perforated layers and for welding are described above.

[0079] Another aspect of the present invention relates to an assembly comprising a bipolar plate and a laminate manufactured according to the present invention on the bipolar plate, wherein the perforated layer associated with the first perforated layer contacts the bipolar plate. The above definitions and embodiments similarly apply to this aspect of the present invention. The following definitions and embodiments similarly apply to other aspects of the present invention.

[0080] The perforated layer opposite the first perforated layer and contacting the bipolar plate has a large maximum opening size (Dx). This preferably enables ensuring mass transfer along the interface BPP-PTL. In a bilayer laminate, the perforated layer contacting the bipolar plate is the second perforated layer. In this case, Dx corresponds to D2. In a trilayer laminate, the perforated layer contacting the bipolar plate is the third perforated layer. In this case, Dx corresponds to D3.

[0081] The platform width (LW) of the bipolar plate and the maximum opening size (Dx) of the perforated layer opposite the first perforated layer preferably satisfy the following inequality (I-12):

[0082] Dx≥(1 / 3)×LW (I-12).

[0083] This design preferably further enables ensuring mass transfer along the interface BPP-PTL.

[0084] The platform width (LW) of the bipolar plate can be selected in the range from 0.5 mm to 3.0 mm, preferably from 0.7 mm to 2.0 mm, and most preferably from 1.0 mm to 1.5 mm. The channel width (CW) of the bipolar plate can be selected in the range from 0.7 mm to 3.0 mm, preferably from 1.0 mm to 2.7 mm, and most preferably from 1.0 mm to 2.5 mm.

[0085] The bipolar plate can be combined with the laminate, for example, by bonding or welding. Preferably, the perforated layer opposite the first perforated layer is welded to the bipolar plate. After welding, a single integrated component BPP+PTL is obtained, and the ohmic resistance at the intermediate layer can preferably be significantly reduced / avoided. In addition, the need for a protective coating at the BPP / PTL interface can preferably be eliminated.

[0086] Another aspect of the invention relates to an electrochemical device comprising: a laminate according to the invention or a component according to the invention. The above definitions and embodiments similarly apply to this aspect of the invention. The following definitions and embodiments similarly apply to other aspects of the invention.

[0087] The electrochemical device can be, for example, a proton exchange membrane water electrolyzer (PEMWE), an anion exchange membrane water electrolyzer (AEMWE), and an alkaline water electrolyzer (ALKWE). Other components of the device are known in the art. For example, a bipolar plate, a porous transport layer anode, a porous transport layer cathode, an anode catalyst layer, a cathode catalyst layer, and a proton exchange membrane can be applied. The laminate according to the invention can be used as a porous transport layer, preferably as an anode porous transport layer, possibly in combination with the bipolar plate in the component according to the invention. Figure 1 A possible PEMWE is depicted in. The first perforated layer (11) preferably contacts the anode catalyst layer.

[0088] The dimensions defined by the above inequalities preferably ensure proper water and gas transport between the channels of the BPP and the catalyst layer on the one hand, allowing the entire CL surface to contact the water flow. On the other hand, the mechanical stability of this design is sufficient to withstand the pressure conditions during operation, while contributing to strengthening the performance of the membrane electrode to withstand high pressure differences. Due to the overall goal of applying a thinner polymer membrane (≤50 μm), the geometry of the top layer / first perforated layer (11) can become crucial when providing sufficient mechanical stability for the CCM. This is one of the important factors that can determine the design preference for small openings for the top layer / first perforated layer together with the active contact area.

[0089] The main dimension of the laminate of the invention is the first maximum opening dimension D1, while the remaining dimensions of each layer support the criteria for mass transfer and mechanical stability mentioned above. The type of membrane used will determine the optimal maximum opening dimension. For example, when using a very thin membrane such as Nafion 212 with an average thickness of 50 μm, the maximum opening dimension is preferably close to 50 μm. In addition, to improve mass transfer, it is preferable to maximize the ratio D1:T1.

[0090] Furthermore, the active area (or diffusion-free contact area) can be maximized by avoiding deformation in the catalyst layer and creating a uniform pressure distribution. This can be achieved, for example, by reducing the maximum opening size of the top layer and limiting the opening porosity to 50% to create a very large free contact area. Additionally, in-plane mass transport of the laminate can be improved by optimizing the transport of gas and water at the BPP / PTL interface. For example, improved mass transport can be achieved by increasing the maximum opening size and opening porosity of the layer in direct contact with the flow field of the BPP.

Claims

1. A laminate, characterized in that include: A first perforated layer (11) and a second perforated layer (12) on the first perforated layer (11), wherein each of the first perforated layer (11) and the second perforated layer (12) has an open two-dimensional periodic structure, and The first thickness (T1), the first maximum opening size (D1) and the first opening distance (S1) of the first perforated layer (11) and the second maximum opening size (D2) and the second opening distance (S2) of the second perforated layer (12) satisfy the following inequalities (I-1) to (I-5), D1 ≥ T1(I-1); D1 ≥ S2(I-2); S1≤(2 / 3)×D1(I-3); D2 ≥ 5 × D1 (I-4); and S2≤(1 / 3)×D2(I-5).

2. The laminate according to claim 1, wherein The first thickness (T1) is 25 μm to 200 μm, and the second thickness (T2) of the second perforated layer (12) is 50 μm to 250 μm.

3. The laminate according to claim 1 or 2, wherein: The first perforated layer (11) has a first open porosity (O1) from 30% to 70%, and the second perforated layer (12) has a second open porosity (O2) from 50% to 90%.

4. The laminate according to any one of claims 1 to 3, wherein The first maximum opening size (D1) is from 30 μm to 300 μm, and the second maximum opening size (D2) is from 400 μm to 1500 μm.

5. The laminate according to any one of claims 1 to 4, wherein The first opening distance (S1) is from 20 μm to 100 μm, and the second opening distance (S2) is from 30 μm to 120 μm.

6. The laminate according to any one of claims 1 to 5, further comprising: a third perforated layer (13) on the second perforated layer (12), wherein the third perforated layer (13) has an open two-dimensional periodic structure, and The second maximum opening size (D2) of the second perforated layer (12) and the third maximum opening size (D3) and the third opening distance (S3) of the third perforated layer (13) satisfy the following inequalities (I-6) to (I-8), D2 ≥ 3 × S3 (I-6); S3≤(1 / 4)×D3(I-7); D3≥1.5×D2(I-8).

7. The laminate according to claim 6, wherein The laminate comprises more than three perforated layers, wherein further perforated layers are successively arranged on the third perforated layer and each has a two-dimensional periodic structure of openings, and wherein the following inequalities (I-9) to (I-11) are satisfied: D(n-1)≥3×Sn(I-9); Sn≤(1 / 4)×Dn(I-10); and Dn≥1.5×D(n-1)(I-11), Wherein, n represents the total number of perforated layers, D(n-1) represents the maximum opening size of the (n-1)th perforated layer, Dn represents the maximum opening size of the nth perforated layer, and Sn represents the opening distance of the nth perforated layer.

8. A laminate according to claim 6 or 7, wherein: The third thickness (T3) of the third perforated layer (13) is from 100 μm to 500 μm, and the thickness of the optional additional perforated layers is each independently from 100 μm to 500 μm.

9. A laminate according to any one of claims 6 to 8, wherein The third perforated layer (13) has a third open porosity (O3) of from 60% to 90%, and the optional further perforated layers each independently have an open porosity of from 70% to 90%.

10. A laminate according to any one of claims 6 to 9, wherein The third maximum opening size (D3) is from 600 μm to 2300 μm, and the maximum opening sizes of the optional additional perforated layers are each independently from 600 μm to 2300 μm.

11. A laminate according to any one of claims 6 to 10, wherein The third opening distance (S3) is from 100 μm to 500 μm, and the opening distances of the optional additional perforated layers are each independently from 100 μm to 500 μm.

12. The laminate according to any one of claims 1 to 11, wherein The perforated layer is selected from a perforated titanium sheet, a perforated stainless steel sheet and a perforated nickel-based sheet.

13. A component, characterized in that include: A bipolar plate and a laminate according to any one of claims 1 to 12 on the bipolar plate, wherein a perforated layer opposite to the first perforated layer contacts the bipolar plate.

14. The assembly according to claim 13, wherein A perforated layer opposite the first perforated layer is welded to the bipolar plate.

15. An assembly according to claim 13 or 14, wherein The platform width (LW) of the bipolar plate and the maximum opening size (Dx) of the perforated layer opposite to the first perforated layer satisfy the following inequality (I-12): Dx≥(1 / 3)×LW(I-12).

16. An assembly according to any one of claims 13 to 15, wherein The land width (LW) of the bipolar plate is from 0.5 mm to 3.0 mm, and the channel width (CW) of the bipolar plate is from 1.0 mm to 3.0 mm.

17. An electrochemical device, characterized in that: include: A laminate according to any one of claims 1 to 12 or an assembly according to any one of claims 13 to 16.

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