A bipolar plate, an electrolytic cell and a method for manufacturing a bipolar plate
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XUANNENG SHENG HYDROGEN (SHANGHAI) TECHNOLOGY CO LTD
- Filing Date
- 2026-04-14
- Publication Date
- 2026-06-12
Smart Images
Figure CN122189690A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of proton exchange membrane water electrolyzer technology, specifically to a bipolar plate, an electrolyzer, and a method for preparing the bipolar plate. Background Technology
[0002] Proton exchange membrane (PEM) water electrolyzers have become a key direction for the development of green hydrogen energy due to their outstanding characteristics such as fast start-up speed, high energy conversion efficiency, high purity of produced hydrogen, and excellent dynamic response capability. As a key multifunctional component of the PEM water electrolyzer, the bipolar plate plays a crucial role in conducting current, distributing reactants and products, mechanically supporting the membrane electrodes, and physically isolating the anode and cathode reaction chambers.
[0003] While widely used metal bipolar plates possess excellent mechanical strength, in the harsh environments of PEM electrolyzers operating in highly acidic and high-potential conditions, a dense, poorly conductive passivated oxide layer rapidly forms on their surface, leading to a sharp increase in contact resistance and significantly increasing system energy consumption. To overcome this problem, a protective coating of precious metals such as gold and platinum must be applied to the surface of the metal plate. Although this coating can temporarily isolate the electrolyte and prevent oxidation, under long-term high-temperature and high-potential conditions, atomic interdiffusion occurs at the interface between the protective coating and the metal plate, affecting the conductivity of the coating, and the protective effect of the coating also decays over time. Traditional graphite or composite graphite bipolar plates, while possessing intrinsic corrosion resistance and conductivity, suffer from insufficient intrinsic airtightness due to their porous structure, especially prone to gas permeation under high-voltage operating conditions, resulting in efficiency losses and safety hazards. Furthermore, the high brittleness of graphite bipolar plates necessitates increased thickness to ensure strength, severely restricting the volumetric power density and compact design of the fuel cell stack, making it difficult to meet the development requirements of megawatt-level high-power electrolyzers. Summary of the Invention
[0004] To address the problem that the conductivity of the protective coating of metal bipolar plates gradually decreases due to interfacial interdiffusion in the prior art, this invention provides a bipolar plate, an electrolytic cell, and a method for preparing the bipolar plate, which can ensure that the bipolar plate has stable and long-lasting conductivity.
[0005] In a first aspect, the present invention provides a bipolar plate comprising: a substrate having a first surface and a second surface thereon, the first surface and the second surface being opposite to each other, and a flow field structure being provided on the first surface and / or the second surface; a diffusion barrier layer covering the first surface and / or the second surface where the flow field structure is located, and covering the surface of the flow field structure; and a conductive layer covering the surface of the diffusion barrier layer away from the substrate.
[0006] In the bipolar plate provided by this invention, a diffusion barrier layer covers the substrate, which can block the mutual diffusion between the substrate material and the conductive layer in an electrochemical environment, thereby ensuring the long-term stable low contact resistance and chemical inertness of the conductive layer, and thus enabling the bipolar plate to have stable and durable conductivity. Simultaneously, the diffusion barrier layer allows for a significant reduction in the thickness of the outer conductive layer, significantly reducing the material usage and cost of the conductive layer while maintaining corrosion resistance and conductivity. Furthermore, the diffusion barrier layer provides the bipolar plate with high airtightness, preventing gas permeation problems.
[0007] Preferably, the substrate is a silicon-doped substrate. Silicon-doped substrates possess near-metallic conductivity, providing an efficient current transmission path. Furthermore, the single-crystal dense structure of the silicon-doped substrate allows for high hermeticity and mechanical strength in the bipolar plate, enabling thinner substrates and facilitating ultra-thin bipolar plates. In addition, using silicon-doped substrate material allows for the etching of complex, high aspect ratio flow field structures with micron-level precision using deep reactive ion etching (DRIE), overcoming the limitations of traditional metal (such as titanium) stamping or graphite processing in terms of flow field precision and complexity.
[0008] Preferably, the resistivity of the substrate is less than 0.01 Ω·cm. This ensures that the current can be conducted efficiently and uniformly within the substrate, thereby minimizing localized heating caused by insufficient substrate conductivity. This not only improves the overall energy efficiency of the electrolytic cell but also avoids localized overload or performance degradation caused by uneven current distribution, providing a fundamental guarantee for the stable and reliable operation of the bipolar plate under megawatt-level high power and high current density conditions.
[0009] Preferably, the diffusion barrier layer is made of one of the following materials: titanium, chromium, tantalum, molybdenum, tungsten, titanium nitride, chromium nitride, tantalum nitride, molybdenum nitride, and tungsten nitride. These materials have high melting points and low diffusion coefficients, allowing the diffusion barrier layer to remain stable at high temperatures and effectively block interdiffusion between the substrate layer and the conductive layer. Furthermore, the diffusion barrier layer formed from these materials has a high structural density, which can improve the compactness of the bipolar plate.
[0010] Preferably, the conductive layer is made of gold, platinum, iridium, ruthenium, or alloys formed from two or more of these materials. These materials possess good chemical inertness, ensuring that the conductive layer will not be damaged by corrosion or form a high-resistivity oxide film. Furthermore, these materials have high conductivity, ensuring efficient operation of the electrolytic cell.
[0011] Secondly, the present invention also provides an electrolytic cell comprising the aforementioned bipolar plate.
[0012] Thirdly, the present invention also provides a method for preparing a bipolar plate, which includes the following steps: S1: providing a substrate and forming the flow field structure on the first surface and / or the second surface of the substrate; S2: depositing a diffusion barrier layer on the first surface and / or the second surface where the flow field structure is located and on the surface of the flow field structure; S3: depositing a conductive layer on the surface of the diffusion barrier layer.
[0013] Preferably, in step S1, a photolithography process is used. First, photoresist is coated on the first surface and / or the second surface. A pattern corresponding to the flow field structure is formed on the photoresist by exposure and development. Then, using the photoresist as a mask, a deep reactive ion etching process is used to etch the flow field structure on the first surface and / or the second surface. Finally, the photoresist is removed.
[0014] By combining photolithography with deep reactive ion etching (DRIE), three-dimensional flow field structures with high aspect ratios and arbitrarily complex patterns can be fabricated on substrate surfaces with micron-level precision, achieving design freedom and accuracy unattainable by traditional machining. This not only significantly optimizes flow field performance but also provides better processing consistency and higher surface quality. It is particularly suitable for doped silicon substrates or other substrates compatible with semiconductor processes, making it the preferred process path for achieving high performance, high reliability, and mass production of bipolar plates.
[0015] Preferably, step S2 specifically involves using reactive magnetron sputtering to deposit a diffusion barrier layer on the first surface and / or the second surface in a vacuum environment and an inert gas atmosphere; step S3 specifically involves using reactive magnetron sputtering to deposit a conductive layer on the surface of the diffusion barrier layer in a vacuum environment and an inert gas atmosphere, or using electroplating to electroplat a conductive layer on the surface of the diffusion barrier layer.
[0016] Step S2 employs reactive magnetron sputtering to deposit a diffusion barrier layer. This process forms a dense and precisely composed thin film, ensuring high hermeticity and barrier performance of the diffusion barrier layer. Furthermore, this process has good coverage capabilities, ensuring that every surface of complex flow field structures is covered, forming a complete and seamless anti-diffusion barrier layer. Step S3 uses either reactive magnetron sputtering or electroplating. Reactive magnetron sputtering yields a conductive layer with high purity and uniform thickness; while electroplating, while meeting performance requirements, has relatively lower production costs and higher deposition efficiency. Using the aforementioned processes ensures the high-quality and highly consistent fabrication of both the diffusion barrier layer and the conductive layer.
[0017] The beneficial effects of this invention are as follows: By setting a diffusion barrier layer, not only can the problem of conductivity decay caused by interfacial interdiffusion in traditional metal bipolar plates be solved, ensuring the long-term stability of low contact resistance on the working surface and giving the bipolar plate stable and durable conductivity, but the precious metal conductive layer can also be significantly thinned, which can significantly reduce the material cost of the bipolar plate. At the same time, the use of a silicon-doped substrate can give the bipolar plate higher airtightness and mechanical strength, which helps to achieve ultra-thin bipolar plates and improve the power density of the fuel cell stack. Attached Figure Description
[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0019] Figure 1 This is a schematic diagram of the structure of a bipolar plate according to an embodiment of the present invention.
[0020] Explanation of reference numerals in the attached figures: 1. Substrate; 2. Diffusion barrier layer; 3. Conductive layer. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] The following is combined Figure 1 The following describes embodiments of the present invention.
[0023] According to an embodiment of the present invention, in a first aspect, a bipolar plate is provided, such as... Figure 1 As shown, it includes: a substrate 1, on which a first surface and a second surface are provided, the first surface and the second surface being opposite to each other, and a flow field structure being provided on the first surface and / or the second surface; a diffusion barrier layer 2, covering the first surface and / or the second surface where the flow field structure is located, and covering the surface of the flow field structure; and a conductive layer 3, covering the surface of the diffusion barrier layer 2 away from the substrate 1.
[0024] The phrase "diffusion barrier layer 2 covers the first surface and / or the second surface where the flow field structure is located, and covers the surface of the flow field structure" can be understood as follows: when only the first surface has a flow field structure, both the first surface and the inner and outer surfaces of the flow field structure are provided with diffusion barrier layer 2 and conductive layer 3, and the second surface may or may not be provided with diffusion barrier layer 2; when only the second surface has a flow field structure, both the second surface and the inner and outer surfaces of the flow field structure are provided with diffusion barrier layer 2 and conductive layer 3, and the first surface may or may not be provided with diffusion barrier layer 2; when both the first and second surfaces have flow field structures, the first surface, the second surface, and the inner and outer surfaces of the two flow field structures are all provided with diffusion barrier layer 2 and conductive layer 3.
[0025] In the bipolar plate provided in this embodiment, a diffusion barrier layer 2 covers the substrate 1, which can block the mutual diffusion between the substrate 1 material and the conductive layer 3 in an electrochemical environment. This ensures the long-term stable low contact resistance and chemical inertness of the conductive layer 3, thereby giving the bipolar plate stable and durable conductivity. Simultaneously, the presence of the diffusion barrier layer 2 allows for a significant reduction in the thickness of the outer conductive layer 3, significantly reducing the material usage and cost of the conductive layer 3 while maintaining corrosion resistance and conductivity. Furthermore, the diffusion barrier layer 2 enables the bipolar plate to have high airtightness, preventing gas permeation problems.
[0026] Optionally, the flow field structure can be one of the three-dimensional flow fields in the prior art, such as a serpentine flow field, a parallel direct current flow field, or a lattice flow field. Of course, it can also be other complex flow field structures. In this embodiment, the flow field structure is a serpentine flow field.
[0027] Furthermore, substrate 1 is a silicon-doped substrate. It can be understood that a silicon-doped substrate is a structure formed by doping impurity atoms into a pure silicon substrate, transforming the pure silicon substrate from a semiconductor into a conductor. Silicon-doped substrates possess near-metallic conductivity, providing an efficient current transmission path. Moreover, the single-crystal dense structure of the silicon-doped substrate allows for higher hermeticity and mechanical strength in the bipolar plate, enabling thinner substrate 1 and facilitating the ultra-thinning of the bipolar plate. In addition, by using silicon-doped substrate 1, complex, high aspect ratio flow field structures can be etched onto the silicon-doped substrate with micron-level precision using deep reactive ion etching (DRIE), overcoming the limitations of traditional metal (such as titanium) stamping or graphite processing in terms of flow field precision and complexity.
[0028] Optionally, the doped silicon substrate is a phosphorus-doped silicon substrate or a boron-doped silicon substrate.
[0029] Furthermore, the resistivity of substrate 1 is less than 0.01 Ω·cm. This ensures that current can be conducted efficiently and uniformly within substrate 1, thereby minimizing localized heating caused by insufficient conductivity of substrate 1. This not only improves the overall energy efficiency of the electrolytic cell but also avoids localized overload or performance degradation caused by uneven current distribution, providing a fundamental guarantee for the stable and reliable operation of the bipolar plate under megawatt-level high power and high current density conditions.
[0030] Optionally, the diffusion barrier layer 2 is made of one of the following materials: titanium, chromium, tantalum, molybdenum, tungsten, titanium nitride, chromium nitride, tantalum nitride, molybdenum nitride, and tungsten nitride. The aforementioned materials have high melting points and low diffusion coefficients, allowing the diffusion barrier layer 2 to remain stable even at high temperatures and effectively block interdiffusion between the substrate layer and the conductive layer 3. Furthermore, the diffusion barrier layer 2 formed from the aforementioned materials has a high structural density, which can improve the compactness of the bipolar plate.
[0031] Optionally, the conductive layer 3 is made of gold, platinum, iridium, ruthenium, or alloys formed from two or more of these materials. These materials possess good chemical inertness, ensuring that the conductive layer 3 will not be damaged by corrosion or form a high-resistivity oxide film. Furthermore, these materials have high conductivity, ensuring efficient operation of the electrolytic cell.
[0032] According to an embodiment of the present invention, in a second aspect, an electrolytic cell is also provided, which includes the bipolar plate of the foregoing embodiment.
[0033] According to an embodiment of the present invention, in a second aspect, a method for preparing a bipolar plate is also provided, which includes the following steps: S1: providing a substrate 1 and forming a flow field structure on a first surface and / or a second surface of the substrate 1; S2: depositing a diffusion barrier layer 2 on the first surface and / or the second surface where the flow field structure is located and on the surface of the flow field structure; S3: depositing a conductive layer 3 on the surface of the diffusion barrier layer 2.
[0034] Further, in step S1, a photolithography process is used. First, photoresist is coated on the first surface and / or the second surface. A pattern corresponding to the flow field structure is formed on the photoresist by exposure and development. Then, using the photoresist as a mask, a deep reactive ion etching process is used to etch the flow field structure on the first surface and / or the second surface. Finally, the photoresist is removed.
[0035] By employing photolithography combined with deep reactive ion etching (DRIE), three-dimensional flow field structures with high aspect ratios and arbitrarily complex patterns can be fabricated on the surface of substrate 1 with micron-level precision, achieving a degree of design freedom and accuracy unattainable by traditional machining. This not only significantly optimizes flow field performance but also provides better processing consistency and higher surface quality. It is particularly suitable for substrates 1 with doped silicon substrates or other compatible semiconductor processes, representing a further process path for achieving high performance, high reliability, and mass production of bipolar plates.
[0036] In this embodiment, the flow field structure formed by the processing is a serpentine flow field with a channel depth of 0.4 mm and a width of 0.7 mm.
[0037] Furthermore, before coating the first and / or second surfaces with photoresist, the substrate 1 is first subjected to RCA cleaning to thoroughly remove organic residues and metal ion contamination from the surface of the substrate 1, so as to obtain an ultra-clean and highly active surface.
[0038] Further, step S2 specifically involves using reactive magnetron sputtering to deposit a diffusion barrier layer 2 on the first surface and / or the second surface in a vacuum environment and an inert gas atmosphere; step S3 specifically involves using reactive magnetron sputtering to deposit a conductive layer 3 on the surface of the diffusion barrier layer 2 in a vacuum environment and an inert gas atmosphere, or using electroplating to electroplat a conductive layer 3 on the surface of the diffusion barrier layer 2.
[0039] Step S2 employs reactive magnetron sputtering to deposit the diffusion barrier layer 2. This process forms a dense and precisely composed thin film, ensuring the high hermeticity and barrier performance of the diffusion barrier layer 2. Furthermore, this process has good coverage capabilities, ensuring that every surface of the complex flow field structure is covered, forming a complete and seamless anti-diffusion barrier layer 2. Step S3 uses either reactive magnetron sputtering or electroplating. Reactive magnetron sputtering yields a conductive layer 3 with high purity and uniform thickness; while electroplating, while meeting performance requirements, has relatively lower production costs and higher deposition efficiency. Using the aforementioned processes ensures the high-quality and highly consistent preparation of both the diffusion barrier layer 2 and the conductive layer 3.
[0040] It is understandable that the working surface of the bipolar plate on the anode side is used to contact the anode side of the membrane electrode, and the working surface on the cathode side is used to contact the cathode side of the membrane electrode.
[0041] Optionally, an N-type (phosphorus-doped) single-crystal silicon wafer with a thickness of 1.0 mm and a resistivity of 0.005 Ω·cm is selected as substrate 1, and the first or second surface of substrate 1 is used as the anode-side working surface of the bipolar plate. When fabricating the diffusion barrier layer 2 on the anode-side working surface, substrate 1 is first placed in the vacuum chamber of a magnetron sputtering apparatus, and then the vacuum chamber is evacuated to a vacuum level below 5.0 × 10⁻⁶.-4 Next, high-purity argon gas is introduced into the vacuum chamber, and the process pressure is maintained between 0.5 Pa and 1.0 Pa. Finally, titanium palladium is sputtered under the aforementioned atmosphere to deposit a dense titanium layer with a thickness of 2.0 μm on the surface of substrate 1, thereby forming diffusion barrier layer 2. In step S3, using the same process conditions, a gold layer with a thickness of 0.3 μm is sputtered on the surface of diffusion barrier layer 2 as conductive layer 3.
[0042] Optionally, a P-type (boron-doped) single-crystal silicon wafer with a thickness of 0.8 mm and a resistivity of 0.008 Ω·cm is selected as substrate 1, and the first or second surface of substrate 1 is used as the cathode-side working surface of the bipolar plate. When fabricating the diffusion barrier layer 2 on the cathode-side working surface, substrate 1 is first placed in the vacuum chamber of a magnetron sputtering apparatus, and then the vacuum chamber is evacuated to a vacuum level below 5.0 × 10⁻⁶. -4 Next, high-purity argon and nitrogen are introduced into the vacuum chamber, and the process pressure is maintained between 0.5 Pa and 1.0 Pa. Finally, using a titanium target, sputtering is performed under the aforementioned atmosphere to deposit a 1.5 μm thick titanium nitride layer on the surface of substrate 1, thereby forming a diffusion barrier layer 2. This layer has higher hardness and is more effective as a barrier layer. In step S3, an electroplating process is used to electroplat a dense platinum layer with a thickness of 0.2 μm on the surface of the diffusion barrier layer 2 as a conductive layer 3.
[0043] It should be noted that the two preparation methods described above are only two optional embodiments, and are not limited to the aforementioned two preparation methods. The first surface and the second surface can be used as the anode-side working surface and the cathode-side working surface, respectively. A diffusion barrier layer 2 and a conductive layer 3 are provided on both the first surface and the second surface. The preparation methods for the diffusion barrier layer 2 and the conductive layer 3 on the first surface and the second surface do not need to be differentiated due to the different polarities; the same method can be used to prepare the diffusion barrier layer 2 and the conductive layer 3 on both surfaces. Alternatively, a diffusion layer and a conductive layer 3 can be simultaneously provided on both the first surface and the second surface, depending on the specific application scenario of the bipolar plate.
[0044] To verify the effectiveness of this invention, a comparative experiment was conducted. Three test electrolytic cells were assembled for the experiment. The first and second electrolytic cells both used the bipolar plates of this invention, and each used two identical bipolar plates, with a diffusion barrier layer and a conductive layer disposed on only a single surface of each bipolar plate; the third electrolytic cell used two conventional titanium plates as a control. The experiments were conducted under identical experimental conditions, and the results are shown in Table 1.
[0045]
[0046] The experimental results show that at 2.0 A / cm 2At the specified current density, the cell voltage of the electrolytic cell using the bipolar plate of this invention is lower than that using a conventional titanium bipolar plate, indicating that the total resistance (including interfacial contact resistance) between the anode and cathode of the electrolytic cell is significantly reduced, and the conductivity of the bipolar plate is better.
[0047] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.
Claims
1. A bipolar plate, characterized in that, include: A substrate (1) is provided with a first surface and a second surface, the first surface and the second surface are opposite to each other, and a flow field structure is provided on the first surface and / or the second surface; A diffusion barrier layer (2) covers the first surface and / or the second surface where the flow field structure is located, and covers the surface of the flow field structure; A conductive layer (3) is applied to the surface of the diffusion barrier layer (2) away from the substrate (1).
2. The bipolar plate according to claim 1, characterized in that, The substrate (1) is a doped silicon substrate.
3. The bipolar plate according to claim 2, characterized in that, The resistivity of the substrate (1) is less than 0.01 Ω·cm.
4. The bipolar plate according to claim 1, characterized in that, The diffusion barrier layer (2) is made of one of the following materials: titanium, chromium, tantalum, molybdenum, tungsten, titanium nitride, chromium nitride, tantalum nitride, molybdenum nitride, and tungsten nitride.
5. The bipolar plate according to claim 1, characterized in that, The conductive layer (3) is made of gold, platinum, iridium, ruthenium, or an alloy of two or more of them.
6. The bipolar plate according to any one of claims 1 to 5, characterized in that, The thickness of the substrate (1) is between 0.5 mm and 3 mm; the thickness of the diffusion barrier layer (2) is between 0.5 μm and 5 μm; and the thickness of the conductive layer (3) is between 0.05 μm and 1 μm.
7. An electrolytic cell, characterized in that, Includes the bipolar plate as described in any one of claims 1 to 6.
8. A method for preparing a bipolar plate, used to prepare the bipolar plate according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Provide a substrate (1) and form the flow field structure on the first surface and / or the second surface of the substrate (1); S2: A diffusion barrier layer (2) is deposited on the first surface and / or the second surface where the flow field structure is located, and on the surface of the flow field structure. S3: Deposit a conductive layer (3) on the surface of the diffusion barrier layer (2).
9. The method for preparing a bipolar plate according to claim 8, characterized in that, In step S1, a photolithography process is used to first coat the first surface and / or the second surface with photoresist, and then form a pattern corresponding to the flow field structure on the photoresist by exposure and development. Using the photoresist as a mask, deep reactive ion etching is then employed to etch the flow field structure on the first surface and / or the second surface. Finally, the photoresist is removed.
10. The method for preparing a bipolar plate according to claim 8, characterized in that, The specific steps of step S2 are as follows: using reactive magnetron sputtering, a diffusion barrier layer (2) is sputtered and deposited on the first surface and / or the second surface in a vacuum environment and an inert gas atmosphere; the specific steps of step S3 are as follows: using reactive magnetron sputtering, a conductive layer (3) is sputtered and deposited on the surface of the diffusion barrier layer (2) in a vacuum environment and an inert gas atmosphere, or using electroplating, a conductive layer (3) is electroplated on the surface of the diffusion barrier layer (2).