Method of applying flow field plate coating

Abstract

A method of applying a coating to a flow field plate of a fuel cell includes applying a solution including a metal-containing precursor and a solvent to at least a portion of the surface of the flow field plate, and evaporating the solvent to form a coating on the at least a portion of the surface of the flow field plate.

Description

Technical Field

[0001] The present disclosure relates to a method of applying a coating to a flow field plate (eg, a bipolar plate) of a fuel cell. Background Art

[0002] Flow field plates (e.g., bipolar plates) are expensive components of a proton exchange membrane fuel cell (PEMFC) stack. In many cases, the flow field plates are the second most expensive component, with the catalyst material typically being the most expensive. Stainless steel plates have been used as a relatively low-cost material for flow field plates. However, during operation of the PEMFC, the stainless steel plates can be susceptible to corrosion in an acidic environment. Although coatings have been proposed to help reduce corrosive behavior, there remains a need for a coating system that adequately protects the flow field plates while not degrading the functional performance of the PEMFC stack. Summary of the invention

[0003] According to one embodiment, a method of applying a coating to a flow field plate of a fuel cell is disclosed. The method includes applying a solution including a metal-containing precursor and a solvent to at least a portion of a surface of the flow field plate. The method further includes evaporating the solvent to form a coating on at least a portion of a surface of the flow field plate.

[0004] According to another embodiment, a method for applying a coating to a flow field plate of a fuel cell is disclosed. The method includes: calculating one or more adsorption energies of one or more reactive elements on a plurality of coating materials, respectively. The method further includes: selecting a protective coating material from the plurality of coating materials based on the one or more adsorption energies. The method also includes: selecting a deposition method for depositing the protective coating material onto a surface of the flow field plate based on the one or more adsorption energies or electronic conductivity of each of the plurality of coating materials. The method further includes: applying the protective coating material to the surface of the flow field plate using the deposition method.

[0005] According to yet another embodiment, a method for applying a coating to a flow field plate of a fuel cell is disclosed. The method includes: calculating one or more adsorption energies of one or more reactive elements on a plurality of coating materials, selecting a protective coating combination from the plurality of coating materials based on the one or more adsorption energies, and applying the protective coating combination to a surface of the flow field plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic perspective view of a fuel cell according to one embodiment, the fuel cell comprising an anode-side flow field plate and a cathode-side flow field plate and a membrane unit located therebetween;

[0007] Figure 2 is a schematic cross-sectional view of a flow field plate including a first protective coating and a second protective coating according to one embodiment;

[0008] Figure 3 is a schematic diagram of a computing platform that may be utilized to implement the DFT algorithm and / or method of one or more embodiments;

[0009] Figure 4 is a schematic diagram depicting a chemical reaction between adsorbed molecules and a BPP coating material according to an embodiment;

[0010] 5a-5g depict schematic diagrams of DFT slab models of representative binary oxides according to one embodiment;

[0011] 6a-6d are graphs depicting the correlation between a first DFT single atom adsorption energy and a second DFT single atom adsorption energy or a surface oxygen or nitrogen DFT vacancy formation energy according to one embodiment. DETAILED DESCRIPTION

[0012] Embodiments of the present disclosure are described herein. However, it is to be understood that the disclosed embodiments are merely examples, and other embodiments may take various forms and alternative forms. The figures are not necessarily drawn to scale; some features may be enlarged or minimized to show the details of a particular component. Therefore, the specific structural and functional details disclosed herein should not be interpreted as being restrictive, but merely as a representative basis for teaching those skilled in the art to adopt the embodiments in various ways. As will be understood by those of ordinary skill in the art, the various features illustrated and described with reference to any one of the figures may be combined with the features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combination of the illustrated features provides a representative embodiment for a typical application. However, for a specific application or implementation, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired.

[0013] Except in the examples or where otherwise explicitly indicated, all numerical quantities indicating the amount of material or the reaction and / or use conditions in this specification are to be understood as being modified by the word "about" when describing the broadest scope of the invention. It is generally preferred to practice within the stated numerical range. Moreover, unless expressly stated to the contrary: percentages, "parts" and ratio values ​​are all by weight; the term "polymer" includes "oligomers", "copolymers" and "terpolymers" and the like; describing a group or class of materials as being applicable or preferred for a given purpose related to the present invention means that a mixture of two or more members of the group or class is also applicable or preferred; the molecular weight provided for any polymer refers to the number average molecular weight; the components described in chemical terms refer to the components when added to any combination specified in the description, and do not necessarily exclude chemical interactions between the components of the mixture after mixing; the first definition of an acronym or other abbreviation applies to all subsequent uses of the same abbreviation herein, and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, the measurement of the same property is determined by the same technology as previously or later cited for a property.

[0014] The present invention is not limited to the specific embodiments and methods described below, as specific components and / or conditions may of course vary. Further, the techniques used herein are only for the purpose of describing specific embodiments of the present invention, and are not intended to be limiting in any way.

[0015] As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. For example, a component mentioned in the singular is intended to include plural components.

[0016] The term "substantially" may be used herein to describe the disclosed or claimed embodiments. The term "substantially" may modify a value or relative property disclosed or claimed in the present disclosure. In such cases, "substantially" may indicate that the value or relative property it modifies is within ±0%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or 10% of the value or relative property.

[0017] Coatings have been proposed for reducing the corrosive effects on flow field plates within the acidic environment of a proton exchange membrane fuel cell (PEMFC) stack. However, previous proposals have not appreciated how these coatings can behave in a functional manner to extend the use and life cycle of flow field plates (e.g., bipolar plates ("BPPs")). Although trial-and-error type experiments and analyses can be performed to study functional coatings, such experiments and analyses do not provide a comprehensive understanding of the physical indicators that can predict the chemical stability of coatings for BPPs and other bipolar plates. Such a comprehensive understanding would require an appreciation of different surface phenomena, such as dissolution, catalytic activity, and corrosion.

[0018] In one or more embodiments herein, computational methods are used to examine the surface phenomena of different BPP coating materials with chemicals present in PEMFC. In one embodiment, a first principle density functional theory (DFT) computational algorithm and / or method can be used to select a protective coating material from a plurality of coating materials. As disclosed herein, the selected protective coating material can be applied to the surface of a BPP or a flow field plate.

[0019] Figure 1 1 is a schematic perspective view of a fuel cell 10 including an anode side flow plate 12 and a cathode side flow plate 14. The fuel cell 10 includes a membrane unit 16, which includes a proton conductive polymer membrane 18. The membrane unit 16 further includes: a first diffusion layer 20 and a second diffusion layer 22 arranged on the side of the polymer membrane 18. The fuel cell 10 has an anode side flow plate 12 and a cathode side flow plate 14. The membrane unit 16 is arranged between the anode side flow plate 12 and the cathode side flow plate 14. The anode side flow plate 12 includes a first surface 28 and an opposite second surface 30. The cathode side flow plate 14 includes a first surface 24 and an opposite second surface 26. The anode side flow plate 12 and the cathode side flow plate 14 can be bipolar plates (BPPs).

[0020] Figure 2 is a schematic cross-sectional view of flow plate 32 including surfaces 34 and 36. Figure 2 As shown in , each of the surfaces 34 and 36 is coated with a protective coating 38 and 40, respectively. The protective coatings 38 and 40 may be conformal coatings, island coatings, or combinations thereof. In other embodiments, only one of the surfaces 34 and 36 is coated with a protective coating. Only a portion of the surfaces 34 and / or 36 may be coated with a protective coating. The protective coatings 38 and / or 40 protect the flow plate 32 from the acidic environment of the PEMFC. The flow plate 32 may be formed of a metal material or graphite such as stainless steel, an aluminum-based alloy, a titanium-based alloy, or a combination thereof. Metallic materials may be susceptible to degradation in the acidic environment of the PEMFC. The protective coatings 38 and / or 40 may slow down or prevent corrosion of the flow plate 32 due to the environment of the PEMFC. The flow plate 32 may be a bipolar plate (BPP).

[0021] In one embodiment, the selection of a BPP coating material is based on the chemical reactivity (e.g., material stability) of the coating material in an acidic environment. A BPP coating material that is chemically inert and does not decompose when in contact with chemicals present during PEMFC operation can slow or prevent corrosion of a BPP (e.g., a stainless steel BPP). The BPP coating layer also creates a physical barrier between the coating layer and the BPP. This physical barrier may provide the following benefits: (1) reduce the formation of pinholes in the BPP; (2) prevent dissolution of Fe (or other metals) from the BPP; and (3) inhibit Fe 2 O 3 Formation. Dissolved metal ions may also cause degradation of the proton exchange membrane in the PEMFC. In some applications, the BPP coating material may also include a conductive coating material. Electronic conduction will allow electrons to be transferred within the cell device of the PEMFC to assist the oxygen reduction reaction (ORR).

[0022] In one embodiment, first principle DFT flat plate model algorithms and / or methods are used to model the actual chemical interface between the BPP coating and the chemicals present in the PEMFC environment. These calculations can be used to design and select the materials for the BPP coating. In one embodiment, the chemicals present and examined are H 3 O + , HF, OH - and / or SO 3 - The chemical molecules represent the chemical species that can degrade or corrode BPP and are commonly present in the PEMFC environment. As described below, single-atom adsorption of H, F, O, and S is used to represent H 3 O + , HF, OH - and / or SO 3 - The chemical interface examined may include adsorbed molecules and BPP coatings. In this context, the adsorbed molecules may be H 3 O + , HF, OH - and / or SO 3 - .

[0023] The DFT slab model algorithm and / or method of one or more embodiments is to use a method such as Figure 350 is implemented by a computing platform such as the computing platform 50 illustrated in . The computing platform 50 may include a processor 52, a memory 54, and a non-volatile storage device 56. The processor 52 may include one or more devices selected from a high-performance computing (HPC) system, which includes a high-performance core, a microprocessor, a microcontroller, a digital signal processor, a microcomputer, a central processing unit, a field programmable gate array, a programmable logic device, a state machine, a logic circuit, an analog circuit, a digital circuit, or any other device that manipulates a signal (analog or digital signal) based on a computer executable instruction residing in the memory 54. The memory 54 may include a single memory device or multiple memory devices, including but not limited to a random access memory (RAM), a volatile memory, a non-volatile memory, a static random access memory (SRAM), a dynamic random access memory (DRAM), a flash memory, a cache memory, or any other device capable of storing information. The non-volatile storage device 56 may include: one or more persistent data storage devices, such as a hard disk drive, an optical drive, a tape drive, a non-volatile solid-state device, a cloud storage device, or any other device capable of persistently storing information.

[0024] The processor 52 may be configured to read into the memory 54 and execute computer executable instructions that reside in the DFT software module 58 of the non-volatile storage device 56 and embody the DFT flat plate model algorithm and / or method of one or more embodiments. The software module 58 may include an operating system and an application program. The software module 58 may be compiled or interpreted from a computer program created using a variety of programming languages ​​and / or techniques, including but not limited to, and using Java, C, C++, C#, Objective C, Fortran, Pascal, Java Script, Python, Perl, and PL / SQL, either alone or in combination.

[0025] After execution by the processor 52, the computer executable instructions of the DFT software module 58 can cause the computing platform 50 to implement one or more of the DFT algorithms and / or methods disclosed herein. The non-volatile storage device 56 can also include DFT data 60 that supports the functions, features, calculations, and processing of one or more embodiments described herein.

[0026] The program code embodying the algorithms and / or methods described herein can be distributed individually or collectively as a program product in a variety of different forms. The program code can be distributed using a computer-readable storage medium having computer-readable program instructions for causing a processor to perform various aspects of one or more embodiments. Computer-readable storage media are non-temporary in nature and may include volatile and non-volatile, removable and non-removable tangible media implemented by any method or technology for storing information such as computer-readable instructions, data structures, program modules or other data. The computer-readable storage medium may further include RAM, ROM, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other solid-state memory technology, portable compact disk read-only memory (CD-ROM) or other optical storage device, cassette, tape, disk storage device or other magnetic storage device, or any other medium that can be used to store desired information and can be read by a computer. The computer-readable program instructions can be downloaded from the computer-readable storage medium to a computer, another type of programmable data processing device or another device, or downloaded to an external computer or external storage device via a network.

[0027] The computer-readable program instructions stored in the computer-readable medium can be used to instruct a computer, other types of programmable data processing devices, or other devices to operate in a particular manner, so that the instructions stored in the computer-readable medium produce the following products: the products include instructions for implementing the functions, actions, and / or operations specified in the flowchart or diagram. In certain alternative embodiments, consistent with one or more embodiments, the functions, actions, and / or operations specified in the flowchart and diagram can be reordered, processed serially, and / or processed simultaneously. In addition, any of the flowchart and / or diagram may include more or fewer nodes or boxes than those consistent with one or more embodiments.

[0028] As generated by the DFT software module 58, Figure 4 is a schematic diagram depicting the chemical reaction between adsorbed molecules and the BPP coating according to an embodiment. Figure 4 As shown in 3 O + The adsorbed molecules 70 and RuO 2 The oxide coating candidate 72. The adsorbed molecule 70 can be any molecule commonly found in PEMFC. Non-limiting examples include H 3 O + , HF, OH - and / or SO 3 -In one or more embodiments, the oxide coating 72 at least partially coats or covers the BPP surface. In certain embodiments, a different type of coating, such as a nitride coating, may at least partially coat and cover the BPP surface. Figure 4 As shown in FIG. 7 , an adsorbed molecule 70 interfaces with an oxide coating 72 at an interface 74. At the interface 74, there may be additional molecules and impurities, such as H 2 O (water or in gaseous form), hydrogen, oxygen, dissolved metals, acids and / or bases.

[0029] The chemisorption reaction occurs at the interface 74 between the adsorbed molecule 70 and the oxide coating 72. The chemisorption reaction is depicted at arrow 76. The chemisorption reaction is followed by a dissociation reaction, as depicted by arrow 78. During the dissociation reaction, anions 80 (H 3 O + O in Figure 4 ) dissociates on the surface metal atoms 82 of the oxide coating 72 (RuO 2 Ru atoms, such as Figure 4 As a further part of the dissociation reaction, the cation 84 (H 3 O + In H, such as Figure 4 ) dissociates on the surface oxygen atoms 86 of the oxide coating 72 (RuO 2 O, such as Figure 4 In one embodiment, a computational algorithm (e.g., a DFT algorithm) is used to calculate the single-atom adsorption trends of (1) anions on surface metal atoms and (2) cations on surface oxygen atoms. The calculation captures both the potential chemical reactions between the adsorbed molecules and the coated substrate as well as the thermodynamic energies.

[0030] although Figure 4 The single-atom adsorption calculations via DFT methods show that H 3 O + However, these methods can also be used to measure other molecules found in the PEMFC environment (such as HF, OH - and SO 3 - ) chemical reactivity. In various embodiments, an accelerated method may be used by combining twenty-three (23) different binary oxides and nitrides (MgO, Al 2 O 3 、TiO 2 、ZrO 2 、ZnO、SnO 2 Cr 2 O 3、MoO 3 、MoO 2 , NbO, TiO, TiN, ZrN, NbN, VN, MoN, CrO 2 、RuO 2 , CuO, NiO, MnO 2 、SiO 2 and Fe 2 O 3 ) uses a single atom (such as H, F, O, S, etc.) to represent H 3 O + H, HF, F, SO 3 - S and OH - In other embodiments, the selected oxides and nitrides are not binary and may include additional metal atoms, such as ternary oxides or nitrides. For each system, a surface facet is selected for each oxide and nitride. In one embodiment, the surface facet may be an energetically stable surface facet. In another embodiment, the most energetically stable surface facets selected based on experiments and / or calculations are as follows: 001) MgO, (001) Al 2 O 3 、(101)TiO 2 、(-111)ZrO 2 , (110) ZnO, (110) SnO 2 、(001)Cr 2 O 3 、(010)MoO 3 、(110)MoO 2 , (001)NbO, (001)TiO, (001)TiN, (001)ZrN, (001)NbN, (001)VN, (001)MoN, (110)CrO 2 、(110)RuO 2 , (111)CuO, (100)NiO, (110)MnO 2 、(001)SiO 2 and (001) Fe 2 O 3 .

[0031] Metal oxides and nitrides can be represented by DFT flat plate models. Figures 5a to 5g depict schematic diagrams of DFT flat plate models of representative binary oxides according to one embodiment. Figure 5a depicts a flat plate model 90 of (001) MgO. Figure 5b depicts a flat plate model 90 of (001) Al 2 O 3Figure 5c depicts the flat plate model 94 of (110) ZnO. Figure 5d depicts the flat plate model 95 of (101) TiO 2 The flat plate model 96. Figure 5e depicts the (110)RuO 2 The flat plate model 98. Figure 5f depicts the (-111) ZrO 2 Figure 5g depicts the (001) SiO 2 Tablet model 102.

[0032] Table 1 below reports the DFT single-atom adsorption energies of H, F, O, and S for the following slab models: (001) MgO, (001) Al 2 O 3 、(101)TiO 2 、(-111)ZrO 2 , (110) ZnO, (110) SnO 2 、(001)Cr 2 O 3 、(010)MoO 3 、(110)MoO 2 , (001)NbO, (001)TiO, (001)TiN, (001)ZrN, (001)NbN, (001)VN, (001)MoN, (110)CrO 2 、(110)RuO 2 , (111)CuO, (100)NiO, (110)MnO 2 、(001)SiO 2 and (001) Fe 2 O 3 The DFT single-atom adsorption energies of H, F, O, and S are listed in Table 1 as ∆E H, ads , ∆E F, ads , ∆E O, ads and ∆E ,S, ads ∆E H, ads , ∆E F, ads , ∆E O, ads and ∆E S, ads The units of ∆E are in eV. Table 1 also includes the calculated results of the DFT vacancy formation energies of surface oxygen or nitrogen as ∆E in eV. O(N), vac . ∆E O(N), vac The value indicates the energy cost of removing surface anions from the coating material. In many cases, the decomposition reaction can be initiated by a surface dissolution step. Therefore, having high oxygen or nitrogen vacancy formation energy generally leads to higher coating stability. Table 1 also includes the approximate range of experimental conductivity (Exp. σ) in S / m.

[0033] Table 1 is included below:

[0034]

[0035] In one embodiment, a positive DFT adsorption energy indicates a high stability of the coating material (i.e., it takes energy to react), while a negative DFT adsorption energy indicates that the coating material and the adsorbate will react (e.g., spontaneously). As a control, certain metal oxides known to react with acids are included in the group of metal oxides examined. For example, according to Table 1, (001)SiO 2 and (110)MnO 2 All have negative adsorption energies. These calculations show that SiO 2 and MnO 2 With HF, H 2 SO 4 This is consistent with known experimental data for other acid reactions. In one embodiment, the calculation results are used to classify twenty-three (23) oxides and nitrides into four categories: (1) protective, but insulating; (2) less protective than (1) and moderately conductive; (3) not very protective, but conductive; and (4) not ideal BPP coating candidates. In one embodiment, each oxide and / or nitride in category (1) is more protective than each oxide and / or nitride in category (2), and each oxide and / or nitride in category (1) is less conductive than each oxide and / or nitride in category (2).

[0036] The protective properties of each of the oxides and / or nitrides can be measured by corrosion current. In one embodiment, the corrosion current of the class (1) molecules can be less than or equal to any one of the following values, or within the range of any two of the following values: 0.8, 0.9, 1.0, 1.1, 1.2, and 1.5 µAcm at 80°C and pH 1 to 4 in the presence of about 0.1 ppm HF in solution. -2 In one embodiment, the corrosion current of the class (2) molecules may be less than or equal to any one of the following values, or within the range of any two of the following values: 2.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, and 12.0 µAcm at 80°C and pH 1 to 4 in the presence of about 0.1 ppm HF in solution. -2 In one embodiment, the conductivity of the class (1) molecules may be greater than or equal to any of the following values, or within the range of any two of the following values: 100, 10 3 , 10 4 and 10 5 S cm -1In one embodiment, the conductivity of the class (2) molecules can be greater than or equal to any one of the following values, or within the range of any two of the following values: 0.1, 1, 10, and 100 S cm -1 The interfacial contact resistance between the SS BPP and the given class (1) or (2) coating molecules can be less than or equal to 0.01, 0.5 and 0.1 Ohmcm 2 .

[0037] In one embodiment, based on the data from Table 1, the following oxides belong to category (1) (protective, but insulating): (001) MgO, (001) Al 2 O 3 、(101)TiO 2 and (-111)ZrO 2 In one embodiment, the following oxides belong to category (2) (less protective than (1) and moderately conductive): (110) ZnO, (110) SnO 2 、(001)Cr 2 O 3 、(010)MoO 3 and (110)MoO 2 In one embodiment, the following oxides and nitrides belong to category (3) (relatively not very protective): (001) NbO, (001) TiO, (001) TiN, (001) ZrN, (001) NbN, and (001) VN. In one embodiment, the following oxides and nitrides belong to category (4) (not ideal BPP coating candidates): (001) MoN, (110) CrO 2 、(110)RuO 2 , (111)CuO, (100)NiO, (110)MnO 2 、(001)SiO 2 and (001) Fe 2 O 3 .

[0038] In one embodiment, oxides or nitrides with four (4) positive adsorption energies are considered to be class (1) (very protective) oxides or nitrides, and they are generally insulating. Oxides or nitrides with three (3) positive adsorption energies can be considered to be class (1) (very protective) oxides or nitrides, and they are generally insulating. Oxides or nitrides with two (2) positive adsorption energies can be considered to be class (2) (less protective than (1)) oxides or nitrides, where they are found to be moderately conductive.

[0039] An oxide or nitride with a one (1) positive adsorption energy may be considered a class (3) (relatively less protective, but conductive) oxide or nitride. An oxide or nitride with a zero (1) positive adsorption energy may be considered a class (4) (not a good candidate for a BPP coating). In one embodiment, the classifications identified above may be altered based on other data about the oxide or nitride. For example, (111) CuO has a two (2) positive adsorption energy (for OH - and SO 3- stability, but ΔE OH, ads close to zero) and two (2) negative adsorption energies (with H 3 O+ and HF reactions), and therefore are considered to be in category (4).

[0040] In another embodiment, the first DFT single-atom absorption energy (ΔE X，ads ) and the second DFT single-atom absorption energy (ΔE Y，ads ) or the surface oxygen or nitrogen DFT vacancy formation energy (ΔE O（N），vac ) is related. FIG6a to FIG6d illustrate a first DFT single atom adsorption energy (∆E) according to one embodiment. X，ads ) and the second DFT single-atom adsorption energy (∆E y，ads ) or the surface oxygen or nitrogen DFT vacancy formation energy (ΔE O(N）, vac ) for the twenty-three (23) oxides and nitrides of Table 1, the graph 110 of FIG. 6a plots ΔE as a function of O（N），vac ΔE as a function of (in eV) H，ads (in eV). For the twenty-three (23) oxides and nitrides of Table 1, graph 112 of FIG. 6b plots the ∆E O，ads (in eV) as a function of ∆E F，ads (in eV). For the twenty-three (23) oxides and nitrides of Table 1, graph 114 of FIG. 6c plots ΔE as a function of O，ads ΔE as a function of (in eV) S，ads (in eV). For the twenty-three (23) oxides and nitrides of Table 1, graph 116 of FIG6d plots the ∆E H，ads (in eV) as a function of ∆E F，ads (in eV).

[0041] In one embodiment, if the material is located in one (1), two (2), three (3), or four (4) upper right quadrants of the graphs 110, 112, 114, and 116, it may be determined that an oxide or nitride should be utilized. As shown in FIG6a, graph 110 includes upper right quadrant 118. As shown in FIG6b, graph 112 includes upper right quadrant 120. As shown in FIG6c, graph 114 includes upper right quadrant 122. As shown in FIG6d, graph 114 includes upper right quadrant 124. In graph 110, the upper right quadrant may be identified as ∆E H，ads In the range of 0.0 eV ±1, 2, 5 or 10% or more, and ∆E O（N），vac In the range of greater than or equal to 3.5 eV ± 1, 2, 5, or 10%. In graph 112, the upper right quadrant can be identified as ∆E F，ads In the range of greater than or equal to -2.5 eV ±1, 2, 5 or 10%, while ∆E O，ads In the range of greater than or equal to -0.5 eV ± 1, 2, 5, or 10%. In graph 114, the upper right quadrant may be identified as ∆E S，ads In the range of greater than or equal to -1.5 eV ±1, 2, 5 or 10%, while ∆E O，ads In the range of greater than or equal to -0.5 eV ± 1, 2, 5, or 10%. In graph 116, the upper right quadrant may be identified as ∆E F，ads In the range of greater than or equal to -2.5 eV ±1, 2, 5 or 10%, while ∆E H，ads In the range of greater than or equal to 0.0 eV ± 1, 2, 5 or 10%.

[0042] The protective coating material can be ABO X A ternary oxide of the form wherein A is a metal from class (1) of metal oxides and B is a metal from class (2) of metal oxides. The composition ratio between A and B may vary (e.g., A 0.1 B 0.9 O X , A 0.2 B 0.8 O X , A 0.3 B 0.7 O X , A 0.8 B 0.2 O X , A 0.9 B 0.1 O X ABO can be converted to XApplied to the surface of the flow plate. The protective coating can be a composite of a material from category (1) and a material from category (2). In another embodiment, the protective coating can be a composite of a material selected from category (1) or category (2) and a material selected from category (3).

[0043] In one or more embodiments, the electronic conductivity of the oxide or nitride may be considered to optimize the coating material. A material having an experimental electronic conductivity (σ) of any of the following values ​​or within the range of the following two values: 10 -14 , 10 -12 , 10 -10 and 10 -8 S / cm, it can be considered insulating. A material has an experimental electronic conductivity (σ) in any of the following values ​​or in the range of the following two values: 10 -8 , 10 -5 , 10 -2 , 10 1 and 10 3 S / cm, it is considered semiconducting. A material has an electronic conductivity (σ) greater than any of the following values: 10 3 , 10 4 and 10 5 S / cm, it can be considered a conductor. If an oxide or nitride material is considered to be insulating, a relatively thin nanoscale coating layer (e.g., applied using atomic layer deposition techniques) can be applied, which is configured to enable electron transfer on a short length scale. The thickness of the relatively thin nanoscale coating layer can be any one of the following values ​​or within a range of any two of the following values: 1, 5, 10, 25, 50, 75, and 100 nm. If the oxide or nitride material has an electronic conductivity greater than the insulating range, a relatively thick coating layer (e.g., applied using a metal deposition process) can be applied, which can enhance the stability and protection of the coating layer. The thickness of the relatively thick coating layer can be any one of the following values ​​or within a range of any two of the following values: 50 nm, 100 nm, 500 nm, 1 μm, 10 μm, and 100 μm.

[0044] A protective coating material (e.g., a metal oxide or nitride) can be applied to the surface of the flow field plate using a variety of different processes. Non-limiting examples of such processes include (1) metal deposition, (2) atomic layer deposition (ALD), and / or (3) solution-based deposition. In one embodiment, a metal electrodeposition process can be used to deposit the protective coating material on the surface of the flow field plate. In a first step, a thin film metal or intermetallic film material is formed on the surface. In a second step, the thin film metal or intermetallic material is heat treated at an elevated temperature (e.g., in the range of 100 to 2,000°C) to form a metal oxide on the surface. Non-limiting benefits of this type of process are scalability and relatively low impurities. Factors to consider when using this type of process are adhesion and contact angle, which depend on the deposition technique and the type of precursor selected.

[0045] Another method that can be utilized to apply the protective coating is an atomic layer deposition (ALD) process. The process can be based on a chemical vapor deposition (CVD) process. The CVD process can be used to create a highly uniform and conformal coating configuration. In another embodiment, other types of physical vapor deposition (PVD) processes or sputtering techniques can be utilized.

[0046] Another treatment is a solution-based method. A metal-containing precursor (such as M(NO 3 ) X and MCl X ) is dissolved in a solvent (such as deionized H 2 O and / or non-aqueous solvents (e.g., ethanol, acetone, isopropanol, etc.) to form a metal-containing precursor solution. The metal-containing precursor solution can be applied to a flow field plate (e.g., BPP). This step can be followed by evaporation, drying and / or heat treatment steps. Non-limiting benefits of this type of processing are scalability and versatility. The resulting coating may have low conformality (e.g., island-type coatings).

[0047] In one embodiment, the class (1) protective coating material may be applied using an ALD process or a solution-based approach. The ALD process produces a nanoscale coating. The thickness of the nanocoating may be any one of the following values ​​or within the range of any two of the following values: 1, 5, 10, 25, 50, 75, and 100 nm. The solution-based approach may result in an island-type coating of the protective coating material. In this embodiment, the protective coating material as an oxide may be undoped and / or partially doped with nitrogen or fluorine and any other anions from the periodic table (including S, C, Cl, P, etc.) to further enhance the electronic conductivity of the resulting protective coating. In another embodiment, cation and / or anion vacancies may help increase the conductivity of the resulting protective coating material.

[0048] In another embodiment, a metal deposition process can be used to apply a category (2) protective coating to form a protective coating. The thickness of the protective coating can be any one of the following values ​​or within a range of any two of the following values: 50 nm, 100 nm, 500 nm, 1 μm, 10 μm, and 100 μm.

[0049] Although exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms covered by the claims. The words used in the specification are descriptive rather than restrictive, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As previously mentioned, the features of the various embodiments can be combined to form further embodiments of the present invention that may not be explicitly described or illustrated. Although various embodiments can be described as providing advantages or being preferred over other embodiments or implementations of the prior art with respect to one or more desired characteristics, it is recognized by those of ordinary skill in the art that one or more features or characteristics can be compromised to achieve the desired overall system properties, which depends specifically on the specific application and implementation. These properties may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc. As such, to the extent that any embodiment is described as being less desirable than other embodiments or implementations of the prior art with respect to one or more characteristics, these embodiments are not outside the scope of the present disclosure and may be desirable for a particular application.

Claims

1. A method of applying a protective coating to a flow field plate of a fuel cell, the method comprising: applying a solution comprising a metal-containing precursor and a solvent to at least a first portion of a surface of a flow field plate; evaporating the solvent to form a protective coating on the at least first portion of the surface of the flow field plate, the protective coating being a combination of a first metal oxide or nitride having Mg and a second metal oxide or nitride having Cr; applying a solution comprising a metal-containing precursor and a solvent to at least a second portion of the second surface of the flow field plate; and The solvent is evaporated to form a second protective coating on at least the portion of the second surface of the flow field plate, the second protective coating being a combination of MgO and niobium monoxide (NbO).

2. The method of claim 1, wherein the solvent is water, ethanol, acetone, isopropanol, or a combination thereof.

3. A method of applying a protective coating material to a flow field plate of a fuel cell, the method comprising: applying a solution including a metal-containing precursor and a solvent to at least a portion of a flow field plate; and The solvent is evaporated to form a protective coating material on at least a portion of the surface of the flow field plate to form an island-shaped protective coating material on the surface of the flow field plate, wherein the protective coating material is a combination of MgO and niobium oxide (NbO) or TiO, and the metal-containing precursor includes (a) Mg(NO3)2 or MgCl2 and (b) Nb(NO3)2 and NbCl2 or (c) Ti(NO3)2 and TiCl2.

4. The method of claim 3, wherein the protective coating material combination is MgO and niobium oxide (NbO).

5. The method of claim 3, wherein the combination of protective coating materials is MgO and TiO.

6. The method of claim 3, wherein the metal-containing precursor comprises (a) Mg(NO3)2 and (b) Nb(NO3)2 and NbCl2 or (c) Ti(NO3)2 and TiCl2.

7. A method of applying a protective coating material to a flow field plate of a fuel cell, the method comprising: applying a solution including a metal-containing precursor and a solvent to at least a portion of a flow field plate; and The solvent is evaporated to form a protective coating material on at least a portion of the surface of the flow field plate to form an island-shaped protective coating material on the surface of the flow field plate, wherein the protective coating material is a ternary oxide having a metal A and a metal B, and the composition ratio between the metal A and the metal B is different or the same, the metal A is Mg, and the metal B is Zn, Sn, Cr or Mo. The method according to claim 7 , wherein the metal A is Mg, and the metal B is Sn.

9. The method of claim 7, wherein the metal A is Mg, and the metal B is Cr.

10. The method of claim 7, wherein the metal A is Mg, and the metal B is Zn.

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