JP2018531209A6 - Bipolar plate with force concentrator pattern - Google Patents

Abstract

Aspects of the present disclosure relate to bipolar plate assemblies. The bipolar plate assembly has a frame and a base. At least one of the frame and the base has a shape of a force concentrator pattern or has a first surface with a force concentrator pattern, the force concentrator pattern partially extending over the first surface. Includes raised surfaces. The surface area of the force concentrator pattern over the length of the frame or base is constant throughout, so that when the bipolar plate assembly is under compression, a uniform compression pressure is provided along the length of the frame or base. Arise.
[Selection figure] None

Description

  [001] This application claims the benefit of US Provisional Application No. 62 / 221,276, filed September 21, 2015, which is incorporated by reference in its entirety.

  [002] The present disclosure is directed to bipolar plates, and more particularly to bipolar plates having a force concentrator pattern.

  [003] Electrochemical cells are usually classified as fuel cells or electrolysis cells and are devices that are used to generate a current through a chemical reaction or to induce a chemical reaction using a current flow. is there. Fuel cells convert the chemical energy of fuels (eg, hydrogen, natural gas, methanol, gasoline, etc.) and oxidants (air or oxygen) into electricity and waste that is heat and water. The basic fuel cell includes a negatively charged anode, a positively charged cathode, and an ion conducting material called an electrolyte.

  [004] Different fuel cell technologies use different electrolyte materials. Proton exchange membrane (PEM) fuel cells, for example, utilize polymer ion-conducting membranes as electrolytes. In a hydrogen PEM fuel cell, hydrogen atoms are electrochemically divided into electrons and protons (hydrogen ions) at the anode. Electrons flow through the circuit to the cathode, generating electricity, while protons diffuse through the electrolyte membrane to the cathode. At the cathode, hydrogen protons can react with electrons and oxygen (supplied to the cathode) to produce water and heat.

  [005] Electrolytic cells are representative of fuel cells that operate in reverse. A basic electrolysis cell can function as a hydrogen generator by decomposing water into hydrogen and oxygen gas when an external potential is applied. The basic technology of hydrogen fuel cells or electrolysis cells can be applied to electrochemical hydrogen manipulation, such as electrochemical hydrogen compression, purification, or expansion.

[006] An electrochemical hydrogen compressor (EHC) can be used, for example, to selectively transfer hydrogen from one side of the cell to the other. The EHC may have a proton exchange membrane sandwiched between a first electrode (ie, anode) and a second electrode (ie, cathode). A gas containing hydrogen is in contact with the first electrode, and a potential difference can be applied between the first electrode and the second electrode. At the first electrode, hydrogen molecules can be oxidized and this reaction can produce two electrons and two protons. Two protons are electrochemically sent through the membrane to the second electrode of the cell, where they recombine with two bypassed electrons and are reduced to form hydrogen molecules. The reaction occurring at the first electrode and the second electrode can be expressed as a chemical equation as shown below.
First electrode oxidation reaction: H ₂ → 2H ++ 2e−
Reduction reaction of the second electrode: 2H ++ 2e− → H ₂
Overall electrochemical reaction: H ₂ → H ₂ .

  [007] EHC operating in this manner is sometimes referred to as a hydrogen pump. When the hydrogen accumulated in the second electrode is limited to a limited space, the electrochemical cell compresses the hydrogen or increases the pressure. The maximum pressure or flow rate that an individual cell can produce may be limited based on the cell design. In order to achieve greater compression or higher pressure, multiple cells can be connected in series to form a multi-stage EHC. In the multi-stage EHC, the gas flow path may be designed, for example, such that the compressed output gas of the first cell becomes the input gas of the second cell. Alternatively, single stage cells can be connected in parallel to increase EHC throughput (ie, total gas flow rate). In both single-stage and multi-stage EHC, the cells may be stacked and each cell may include a cathode, an electrolyte membrane, and an anode. Each cathode / membrane / anode assembly constitutes a “membrane electrode assembly” or “MEA”, which is typically supported by bipolar plates on both sides.

  [008] Bipolar plates can provide mechanical support to the EHC and can be physically separated while electrically connecting individual cells in the stack. Bipolar plates can also provide a high pressure zone in which reactants or fuels such as hydrogen accumulate. In addition, the bipolar plate can also act as a current collector / conductor and can also provide a passage for reactants or fuel. Typically, bipolar plates are made from metals such as stainless steel, titanium, etc., and non-metallic electrical conductors such as graphite.

  [009] A hydrogen compressor or hydrogen pump typically has hydrogen accumulated in a second electrode confined to a high pressure zone formed by a bipolar plate. In addition, as the hydrogen continues to form and accumulate, the pressure in the high pressure zone can increase. To reduce the potential for hydrogen leakage and improve safety and energy efficiency, the high pressure zone may be sealed with one or more seals between the bipolar plates. A compressive load can be applied to the bipolar plate of the EHC or EHC stack to compress the seal and create a high pressure zone seal. The seal may include a ring-shaped seal extending around the circumference of the high pressure zone and / or a polymer film coated or laminated on one or more surfaces of the bipolar plate. May be included.

  [010] A sufficient and generally uniform compression pressure needs to be applied to the seal between the bipolar plates. The minimum compression pressure applied may be greater than the yield strength of the seal material so that a sealing surface can be created by deforming the seal material. In some embodiments, the minimum compression pressure may be less than the yield strength of the material. If the compression pressure is not uniform or non-uniform across the sealing surface, the minimum compression pressure may not be applied to some areas on the sealing surface, so that the reactant or May cause fuel leakage. The current option to prevent or reduce the possibility of leakage due to uneven compression pressure applied to the seal is to apply a higher compression load to the bipolar plate to ensure that the minimum compression pressure is applied across the sealing surface It is mentioned to be made. However, applying a higher compressive load not only gives higher compressive pressure on the sealing surface, but also a bipolar where the minimum compressive pressure is already applied and may not withstand the higher compressive pressure. There is a risk of applying a higher compression pressure to the plate location. Thus, higher compressive loads are applied to materials for bipolar plates and / or other parts of an EHC or EHC stack, such as material compatibility, material strength, material cost, manufacturing cost, and ease of manufacturing. High conditions may be required. Therefore, there is a need for a bipolar plate assembly that allows for a more uniform and / or even distribution of compression pressure across the sealing surface and / or bipolar.

  [011] One aspect of the present disclosure is directed to a bipolar plate assembly. The bipolar plate assembly may have a frame and a base. At least one of the frame and base may have the shape of a force concentrator pattern or may have a first surface. The first surface may include a force concentrator pattern, and the force concentrator pattern may include a raised surface that extends partially across the first surface. The surface area of the force concentrator pattern over the length of the frame or base may be entirely constant so that the length of the frame and / or base when the bipolar plate assembly is under compression. A uniform compression pressure is produced along

  [012] Another aspect of the present disclosure is directed to a method of compressing a bipolar plate. The method may include compressing the frame and base of the bipolar plate assembly. At least one of the frame and the base may have the shape of a force concentrator pattern or may have a first surface. The first surface may include a force concentrator pattern, and the force concentrator pattern may include a raised surface that extends partially across the first surface. The surface area of the force concentrator pattern over the length of the frame or base may be generally continuous. The method may further include generating a uniform compression pressure along the length of the frame and / or base when the bipolar plate assembly is under compression.

  [013] Another aspect of the present disclosure is directed to an electrochemical cell. The electrochemical cell may include a pair of bipolar plates and a membrane electrode assembly disposed between the pair of bipolar plates. At least one of the bipolar plates may have a force concentrator pattern shape or may have a first surface. The first surface may include a force concentrator pattern, and the force concentrator pattern may include a raised surface that extends partially across the first surface. The surface area of the force concentrator pattern over the length of the frame or base may be generally continuous. The method may further include generating a uniform compression pressure along the length of the frame and / or base when the bipolar plate assembly is under compression.

[014] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the claimed disclosure.
[015] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure of the present invention and, together with the description, serve to explain the principles of the disclosure.

[016] FIG. 1 is an exploded side view of a portion of an electrochemical cell showing various elements of the electrochemical cell according to an exemplary embodiment. [017] FIG. 2 is a perspective view of a base and frame of a bipolar plate assembly according to an exemplary embodiment. [018] FIG. 3 is a perspective view of the base and frame of a bipolar plate assembly according to an exemplary embodiment. [019] FIG. 4 is a top view of the frame of an exemplary bipolar plate assembly. [020] FIG. 5 is a top view of the frame of an exemplary bipolar plate assembly. [021] FIG. 6 is a perspective view of a frame of a bipolar plate assembly according to an exemplary embodiment. [022] FIG. 7 is an enlarged view of a frame of a bipolar plate assembly according to an exemplary embodiment. [023] FIG. 8 is a perspective view of a base and frame of a bipolar plate assembly according to an exemplary embodiment. [024] FIG. 9 is a top view of a frame of a bipolar plate assembly according to an exemplary embodiment. [025] FIG. 10 is a perspective view of a frame of a bipolar plate assembly according to an exemplary embodiment.

  [026] Reference will now be made in detail to exemplary embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Although described with respect to electrochemical cells for compressing hydrogen, the devices and methods of the present disclosure are various types of fuel cells such as, but not limited to, electrolysis cells, hydrogen purifiers, hydrogen expanders, and hydrogen pumps. It is understood that it can be employed with electrochemical cells.

  [027] FIG. 1 shows an illustration of an exploded side view of an electrochemical cell 100 according to an exemplary embodiment. The electrochemical cell 100 may include an anode 110, a cathode 120, and a proton exchange membrane (PEM) 130 disposed between the anode 110 and the cathode 120. The anode 110, cathode 120, and combined PEM 130 may include a membrane electrode assembly (MEA) 140. PEM 130 is a pure polymer film or a composite film in which other materials such as silica, heteropolyacids, layered metal phosphates, phosphates, and zirconium phosphates are embedded in a polymer matrix. Can be included. The PEM 130 does not conduct electrons but can transmit protons. The anode 110 and the cathode 120 may include a porous carbon electrode containing a catalyst layer. A catalyst material, such as platinum, can increase the reaction of the reactants or fuel.

  [028] The electrochemical cell 100 may further include two bipolar plates 150,160. Bipolar plates 150, 160 can act as support plates, conductors, can provide a path to the respective electrode surfaces for the reactants or fuel, and remove the compressed reactants or fuel. Can provide a passageway. Bipolar plates 150, 160 may also include access channels for cooling fluid (ie, water, glycol, or a mixture of water and glycol). Bipolar plates 150, 160 can separate electrochemical cell 100 from adjacent cells (not shown) in the electrochemical stack. In some embodiments, bipolar plates 150 and / or 160 may function as bipolar plates for two adjacent cells such that each side of bipolar plates 150 and / or 160 contacts a different MEA 140. it can. For example, a plurality of electrochemical cells 100 may be connected in series to form a multi-stage electrochemical hydrogen compressor (EHC), or stacked in parallel to form a single-stage EHC.

  [029] In operation, hydrogen gas may be supplied to the anode 110 through the bipolar plate 150, according to an exemplary embodiment. A potential may be applied between the anode 110 and the cathode 120, and the potential at the anode 110 is greater than the potential at the cathode 120. As the hydrogen at the anode 110 is oxidized, the hydrogen can be separated into electrons and protons. Protons are electrochemically transported or “pumped” through PEM 130, while electrons bypass PEM 130. At the cathode 120 on the opposite side of the PEM 130, the transported protons and detoured electrons are reduced to form hydrogen. As hydrogen continues to form at the cathode 120, the hydrogen can be compressed and pressurized in the high pressure zone created by the bipolar plate 160.

  [030] In some embodiments, each of the bipolar plates 150 and 160 may be formed of two pieces or two elements. For example, FIG. 2 shows one embodiment of a two-element bipolar plate 160 that includes a frame 170 and a base 180. The frame 170 can define a void 190 in fluid communication with the flow structure (not shown) of the base 180. In some implementations, the frame 170 and base 180 may be formed as one integrated part or element. In the following description, the bipolar plate 160 is described, but such disclosure is equally applicable to the bipolar plate 150.

  [031] The frame 170 and base 180 may be generally planar and may have a generally rectangular or elongated profile. In some embodiments, the frame 170 and the base 180 may have other shapes, such as a square, a “race track” (ie, a shape that is substantially rectangular and semi-elliptical on the sides), circular, oval, It may have an oval shape or other shapes. The shape of the frame 170 and base 180 may correspond to other elements of the electrochemical cell 100 (eg, cathode, anode, PEM, flow structure, etc.) or electrochemical cell stack.

  [032] The frame 170 and the base 180 may be designed to be coupled in the same plane. Frame 170 and base 180 may be connected or secured together so that they can be removed, or may be a single integrated piece. Uses one or more attachment mechanisms such as, for example, bonding materials, welding, brazing, soldering, diffusion bonding, ultrasonic welding, laser welding, stamping, riveting, resistance welding, and / or sintering May be. In some embodiments, the bonding material may include an adhesive. Suitable adhesives include, for example, glues, epoxies, cyanoacrylates, thermoplastic sheets (eg, hot melted thermoplastic sheets), urethanes, anaerobic adhesives, UV curable adhesives, and other polymers. In some embodiments, the frame 170 and the base 180 may be connected by a friction fit. For example, one or more seals between elements can cause sufficient friction between the elements when compressed to prevent unexpected sliding.

  [033] In some embodiments, the frame 170 and base 180 can be removably coupled using fasteners, such as screws, bolts, clips, or other similar mechanisms. In some embodiments, the compression rods and nuts may extend through the bipolar plates 150 and 160, or along the outside thereof, and stack the electrochemical cell 100 or a plurality of electrochemical cells 100. Can be used to compress the frame 170 and the base 180 together.

  [034] In some embodiments, the frame 170 and the base 180 can help define a plurality of different pressure zones, eg, the plurality of seals can define one or more different pressure zones. Can do. FIG. 2 illustrates a plurality of different seals and pressure zones according to one embodiment. The plurality of seals may include a first seal 240, a second seal 250, and a third seal 260. The first seal 240 may be entirely contained within the second seal 250, and the second seal 250 may be entirely contained within the third seal 260. This arrangement of seals (ie, one included in the other) can be classified as a cascade seal arrangement. A cascade seal arrangement can provide a number of advantages. For example, a cascade seal arrangement can limit the likelihood of high pressure hydrogen escaping from the electrochemical cell 100 by providing seal overlap in the form of multi-layer seal protection. Reducing the likelihood of hydrogen leaking can benefit safety and energy efficiency. In addition, the cascade seal arrangement also allows the pressure to self-regulate by gradually reducing the high pressure from the high pressure zone to the lower pressure zone.

  [035] The shape of the first seal 240, the second seal 250, and the third seal 260 may generally correspond to the shape of the bipolar plates 150 and 160, as shown in FIG. . The first seal 240 acts as a high pressure seal and can define a portion of the high pressure zone 200 and is designed to contain a first fluid 212 (eg, hydrogen) within the high pressure zone 200. Also good. The first seal 240 can at least define the outer boundary of the high pressure zone 200 between the frame 170 and the base 180. When the frame 170 and the base 180 are connected, or when the frame 170 and the base 180 are formed as one integrated piece, the high pressure zone 200 has at least one flow structure (not shown), for example It may be designed to contain a cathode flow structure and an anode flow structure extending through the void 190.

  [036] A first fluid 212, such as hydrogen, may be formed at the cathode 120 and accumulate in the high pressure zone 200, and the connection between the frame 170 and the base 180 may be at the first seal 240. It may be sealed. The hydrogen in the high pressure zone 200 may be compressed, and as a result, the pressure can be increased as hydrogen continues to form and is collected in the high pressure zone 200. The hydrogen in the high pressure zone 200 may be, for example, a pressure greater than about 10,000 psig, a pressure greater than about 15,000 psig, a pressure greater than about 20,000 psig, a pressure greater than about 25,000 psig, a pressure greater than about 30,000 psig, Or it may be compressed to a pressure greater than about 35,000 psig.

  [037] As shown in FIG. 2, the first seal 240 may be designed to extend to the outer periphery of the high pressure port 210. The high pressure port 210 may be designed to supply or drain the first fluid 212 from the high pressure zone 200. The high pressure port 210 may be in fluid communication with the high pressure port of an adjacent electrochemical cell in a multi-cell electrochemical compressor. High pressure port 210 may be in fluid communication with a cathode flow structure (not shown), which may be disposed on top of base 180 that extends through void 190.

  [038] In some implementations, the second seal 250 can define the outer periphery of the intermediate pressure zone 202. The intermediate pressure zone 202 can be bounded by the first seal 240, the second seal 250, the frame 170, and the base 180. As shown in FIG. 2, the intermediate pressure zone 202 may extend around the circumference of the high pressure zone 200 separated by the first seal 240. The intermediate pressure zone 202 may be designed to contain the second fluid 214. The cross-sectional area and volume of the intermediate pressure zone 202 can vary based on the geometry of the frame 170, base 180, first seal 240, and second seal 250. Intermediate pressure zone 202 may further include one or more intermediate pressure ports 220 and may be in fluid communication therewith. The intermediate pressure port 220 may be designed to drain the second fluid 214 contained within the intermediate pressure zone 202. The intermediate pressure port 220 may be in fluid communication with an anode flow structure (not shown), and the anode flow structure may be disposed on top of the cathode flow structure that extends through the gap 190.

  [039] The shape and number of intermediate pressure ports 220 may vary. For example, the medium pressure port 220 may be square, rectangular, triangular, polygonal, circular, oval, or other shape. The number of intermediate pressure ports 220 may vary between 1 and 25, or more. As shown in FIG. 2, the intermediate pressure ports 220 may be evenly distributed along the length of the frame 170 and base 180 of the bipolar plate 160. In some embodiments, the intermediate pressure port 220 may extend around the entire circumference of the intermediate pressure zone 202.

  [040] In some embodiments, the second fluid 212 discharged via the intermediate pressure port 220 may be re-supplied to the electrochemical cell 100. In some embodiments, the second fluid 214 discharged via the medium pressure port 220 may be collected and reused. The second fluid 214 in the intermediate pressure zone 202 may generally have a lower pressure than the first fluid 212 in the high pressure zone 200.

  [041] In some embodiments, the third seal 260 can define the low pressure zone 204 and may be designed to contain the third fluid 216 within the low pressure zone 204. The low pressure zone 204 can be bounded by the second seal 250, the third seal 260, the frame 170, and the base 180. As shown in FIG. 2, the low pressure zone 204 may extend around the circumference of the intermediate pressure zone 202 separated by the second seal 250. The cross-sectional area and volume of the low pressure zone 204 can vary based on the geometry of the frame 170, base 180, second seal 250, and third seal 260. The low pressure zone 204 may further include one or more low pressure ports 230 and may be in fluid communication therewith. The low pressure port 230 discharges the third fluid 216 collected and / or contained within the low pressure zone 204.

  [042] The shape and number of low pressure ports 230 may vary. For example, the low pressure port 230 may be square, rectangular, triangular, polygonal, circular, oval, or other shape. The number of low pressure ports 230 may vary, for example, between 1 and 50, or more. As shown in FIG. 2, the low pressure port 230 may be spaced between the second seal 250 and the third seal 260, and may be uniform along the length of the bipolar plate 160. May be distributed. In some embodiments, the low pressure port 230 may extend around the entire circumference of the low pressure zone 204.

  [043] In some embodiments, the third fluid 216 discharged via the low pressure port 230 may be re-supplied to the electrochemical cell 100. In some embodiments, the third fluid 216 discharged via the low pressure port 230 may be collected and reused. The third fluid 216 in the low pressure zone 204 may generally have a lower pressure than the first fluid 212 in the high pressure zone 200 and the second fluid 214 in the intermediate pressure zone 202.

  [044] According to an exemplary embodiment, the first seal 240, the second seal 250, and the third seal 260 are different pressure zones of the bipolar plate 160 (eg, high pressure zone 200, intermediate pressure zone 202). , And low pressure zone 204), a pressure exceeding about 15,000 psig, a pressure exceeding about 20,000 psig, a pressure exceeding about 25,000 psig, a pressure exceeding about 30,000 psig, about 35,000 psig Withstand pressures greater than about 40,000 psig, or pressures greater than about 40,000 psig for extended periods of time (eg, greater than 10 years) and many pressure cycles (eg, greater than 1,000 cycles) ) Can be part of the assembly of sealing elements. For example, the first seal 240 can seal the high pressure zone 200 having a pressure in the range of about 25,000 psig to about 40,000 psig, and the second seal 250 can be about 0 psig to about 3,000 psig. The intermediate pressure zone 202 having a pressure in the range of 3 can be sealed, and the third seal 260 can seal the low pressure zone 204 having a pressure in the range of about 0 psig to about 20 psig.

  [045] In some embodiments, bipolar plates 150 and 160 may be designed such that only two pressure zones are formed. For example, bipolar plates 150 and 160 may be designed to form high pressure zone 200 and low pressure zone 204 with only first seal 240 and third seal 260, thereby providing second seal 250 and medium pressure. The zone 202 can be eliminated. It is also anticipated that in some embodiments, bipolar plates 150 and 160 may be designed such that more than three pressure zones are formed. For example, a fourth pressure zone may be formed by adding a fourth seal.

  [046] In order to seal the high pressure zone 200, the intermediate pressure zone 202, and / or the low pressure zone 204 that are conventionally created between the frame 170 and the base 180, and further to seal the high pressure port 210, the first An elastomer seal (eg, an O-ring) is used for the second seal 240, the second seal 250, and / or the third seal 260. Elastomers often have reliability issues in high pressure systems. Elastomeric seals must be either die cut, manually installed, overmolded, or deposited using an xy table and then cured in addition to reducing the robustness and acceptability of the electrochemical cell There is. In addition, the elastomeric seal may require that either the frame 170 or the base 180 have a gland or groove on the surface. Elastomeric seals can be joined to the grooves, but they can be displaced in situ during fabrication, assembly and / or operation. Due to the low reliability caused by the elastomeric seal and the complexity of the fabrication process, in some embodiments a polymer is used to seal at least one of the pressure zones formed between the frame 170 and the base 180. Seals can be used advantageously.

  [047] The polymer seal can be applied to the frame 170 and / or the base 180 by a variety of techniques, such as lamination, spray coating, or dip coating. Utilizing a polymer seal can reduce the complexity of the bipolar plates 150,160. For example, grounds or grooves on the surface of the frame 170 and / or the base 180 can be eliminated. Eliminating the gland or groove makes frame 170 and / or base 180 thinner, reduces the amount of machining and / or manufacturing required, and increases the area of the sealing surface between frame 170 and base 180. The compression pressure that the frame 170 and / or the base 180 needs to withstand can be reduced. In another example, using a polymer seal may allow the frame 170 and base 180 to be formed as one integrated piece, thereby further reducing the thickness of the bipolar plates 150, 160. it can. In addition, the laminated or spray-coated polymer seal can be securely bonded to the frame 170 and / or the base 180 and thus can be held securely in place. The polymer seal allows for lower fabrication costs, lower application costs, and reduced material for the bipolar plates 150 and 160 by less machining the bipolar plates 150 and 160.

[048] As shown in FIG. 3, the polymer seal 175 may be laminated or coated, for example, on one or both surfaces of the frame 170 and / or the base 180. When compressive load is applied to the frame 170 and base 180, the polymer seal 175 can deform to seal the high pressure zone 200, the intermediate pressure zone 202, and / or the low pressure zone 204. The polymer seal 175 may include, for example, containing the first fluid 212 in the high pressure zone 200, containing the second fluid 214 in the intermediate pressure zone 202, and / or containing the third fluid 216 in the low pressure zone 204. It may be designed to help contain within. In some embodiments, the polymer seal 175 may cover some or all of the surface area of the frame 170 and / or the base 180. The polymer seal 175 may have a seal surface that extends over a compressed region between the frame 170 and the base 180, and may be a circle of the high pressure zone 200, the intermediate pressure zone 202, and / or the low pressure zone 204. May extend around the circumference,
[049] In some embodiments, the polymer seal 175 can be used in place of the first seal 240, the second seal 250, and / or the third seal 260. For example, as shown in FIG. 4, the polymer seal 175 can be used with a first seal 240 that seals the high pressure zone 200 and a polymer seal 175 that seals the intermediate pressure zone 202 and the low pressure zone 204. In some embodiments, one or more channels may be formed between the intermediate pressure port 220 and the high pressure zone 200 such that the intermediate pressure port 220 is connected to the first seal 240, high pressure. Allows fluid communication with the zone 200 and / or the anode flow structure (not shown). The polymer seal 175 may also include one or more channels 178, thereby allowing the intermediate pressure port 220 to be in fluid communication with the high pressure zone 200.

  [050] In some embodiments, the polymer seal 175 seals the different pressure zones and has a pressure greater than about 15,000 psig, a pressure greater than about 20,000 psig, a pressure greater than about 25,000 psig, Withstand pressures greater than 30,000 psig, pressures greater than about 35,000 psig, or pressures greater than about 40,000 psig for long periods (eg, greater than 10 years) and many pressure cycles (eg, 1,000 More than a cycle). For example, the polymer seal 175 seals the high pressure zone 200 having a pressure in the range of about 25,000 psig to about 40,000 psig, and seals the intermediate pressure zone 202 having a pressure in the range of about 0 psig to about 3,000 psig. And / or the low pressure zone 204 having a pressure in the range of about 0 psig to about 20 psig can be sealed. This allows the reactant or fuel formed at the cathode 120, such as hydrogen, to be highly compressed, for example, in the high pressure zone 200.

  [051] The dimensions of polymer seal 175, such as shape, thickness, and width, may vary and may be based on the dimensions of electrochemical cell 100 and bipolar plate 160. The thickness of the polymer seal 175 is, for example, from about 0.01 mm to about 0.025 mm, from about 0.025 mm to about 0.05 mm, from about 0.05 mm to about 0.1 mm, from about 0.1 mm to about 0.2 mm, About 0.2 mm to about 0.3 mm, about 0.025 mm to about 0.1 mm, about 0.025 mm to about 0.2 mm, about 0.025 mm to about 0.254 mm, about 0.025 mm to about 0.3 mm, About 0.05 mm to about 0.1 mm, about 0.05 mm to about 0.2 mm, about 0.05 mm to about 0.3 mm, about 0.1 mm to about 0.2 mm, or about 0.1 mm to about 0.3 mm It may be a range. In some embodiments, the polymer seal 175 may be a separate thin polymer film sandwiched between the frame 170 and the base 180. In some embodiments, the polymer seal 175 can be coated or laminated on either the frame 170 or the base 180 or on both the frame 170 and the base 180. In some embodiments, the polymer seal 175 may be applied to the surface of the frame 170 facing the base 180 and / or the surface of the base 180 facing the frame 170. In some embodiments, the polymer seal 175 may be applied to the surface of the frame 170 facing the base 180 of the adjacent cell and / or on the surface of the base 180 facing the frame 170 of the adjacent cell. May be applied. In some embodiments, the polymer seal 175 may be applied to both the frame 170 and / or the surface of the base 180. In some embodiments, the frame 170 may be formed of the material of the polymer seal 175 such that the thickness range of the polymer seal 175 is substantially the same as the thickness range of the frame 170.

  [052] In some embodiments, the first seal 240, the second seal 250, and / or the third seal 260 may be made of a polymer seal 175 as described herein. May be replaced by it. In some embodiments, the polymer seal 175 can be used with the first seal 240, the second seal 250, and / or the third seal 260. In some embodiments, the polymer seal 175, the first seal 240, the second seal 250, and / or the third seal 260 are, but are not limited to, Teflon ™, Torlon®, It may be made of a polymer sealing material such as polyetheretherketone (PEEK), polyethyleneimine (PEI), polyethylene terephthalate (PET), polycarbonate (PC), polyimide, and polysulfone. The polymeric material may be acid resistant and may not leach out materials that are detrimental to the operation of the electrochemical cell 100. In some embodiments, the frame 170 and / or base 180 may be coated with an adhesive designed to aid in sealing. The adhesive may be, for example, an adhesive that is activated by pressure or heat.

  [053] When assembling the bipolar plate 160, the frame 170 and the base 180 (not shown in FIG. 4) can be coupled, and the compression pressure is applied to the frame 170, the base 180, and the frame 170 and / or the base. Applicable to polymer seal 175 applied to 180. In some embodiments, the minimum compression pressure applied may be greater than the yield strength of the polymer seal 175 material so that a sealing surface can be created by deforming the polymer seal 175 material. In some embodiments, if the surface of the frame 170 and / or base 180 to which the polymer seal 175 is applied is substantially polished to create a sealing surface, the minimum compression pressure applied is It does not necessarily have to be larger than the yield strength of the material of the polymer seal 175. The sealing surface may be formed from a compressed region of the frame 170 and / or the base 180. Although the following description refers to frame 170, such disclosure is equally applicable to base 180.

  [054] As shown in FIG. 4, for example, the compressed region of the frame 170 may extend across the top surface of the frame 170. In some implementations, the frame 170 may have an elongated shape that includes a first end 171, a second end 172, and an elongated body 173 extending therebetween. In some embodiments, as shown in FIG. 4, the first end 171 and the second end 172 of the frame 170 may have a wider area compared to the elongated body 173. In general, the compressed area along the elongated body 173 of the frame 170 may be narrower or smaller than the compressed area at the first end 171 and the second end 172 of the frame 170. When a compressive load is applied to the compressed region of the frame 170, the compressed region at the first end 171 and the second end 172 of the frame 170 may become elongated due to the difference in contact area. It is possible to experience a compression pressure that is less than the compressed area along 173. Such a situation can result in non-uniform compression pressure across the compressed areas of the sealing surfaces of the frame 170 and the polymer seal 175. This is because somewhere along the sealing surface, for example, the first end 171 and the first end 171 and the compression pressure may be lower, or in some situations may not meet the minimum compression pressure. There is a possibility of causing fluid leakage in a place close to the second end 172.

  [055] FIG. 5 shows an example where non-uniform compression pressure is applied to the compressed areas of the sealing surfaces of the frame 170 and the polymer seal 175. FIG. The magnitude of the compression pressure is indicated by the hatched density. As shown in FIG. 5, the compression pressure applied at the second end 172 of the frame 170 is less than the compression pressure applied to the elongated body 173 of the frame 170. In this embodiment, if a minimum compression pressure is applied to the compressed area along the elongated body 173 of the frame 170, a compression pressure that is less than the minimum compression pressure is compressed at the second end 172 of the frame 170. This may be applied to a region that is, for example, a fluid leak from the high pressure zone 200 to the medium pressure zone 202, a leak from the medium pressure zone 202 to the low pressure zone 204 or outside the bipolar plate, And / or introduces a potential risk of leakage from the low pressure zone 204 to the exterior of the bipolar plate. Alternatively, if the compression pressure applied to the compressed region at the second end 172 of the frame 170 is equal to or sufficiently higher than the minimum compression pressure, the compressed along the elongated body 173 of the frame 170 The compression pressure applied to the region may substantially exceed the maximum compression pressure that the material of the frame 170 can withstand, and so more design of the frame 170 to accommodate the excess compression pressure. Requirements and / or careful design may be required.

  [056] In order to increase the uniformity of the compression pressure applied to the compressed area of the sealing surface of the frame 170 and / or base 180 and the polymer seal 175, the frame 170 and / or base 180 may be a force concentrator pattern ( force concentrator pattern) 300 can be defined. As shown in FIG. 6, the force concentrator pattern 300 may be a surface that protrudes from the top and / or bottom of the frame 170 and / or the base 180. For example, the force concentrator pattern 300 can be produced by chemical etching or machining of the upper surface of the frame 170. In some embodiments, the force concentrator pattern 300 can be used to machine the frame 170 and / or the base 180 such that the surface profile of the frame 170 and / or the base 180 is substantially the same as the force concentrator pattern 300. It can be fabricated by processing to remove the material of the frame 170 and / or the base 180. For example, the force concentrator pattern 300 can be created by removing or etching away a portion of the material of the frame 170 near the first end 171 and the second end 172. Although the following description describes force concentrator pattern 300 as a raised surface, such disclosure is equally applicable to force concentrator pattern 300 that is substantially the same as the profile of frame 170 and / or base 180. is there.

  [057] As shown in FIG. 7, for example, the force concentrator pattern 300 may also be described as a raised surface 300 ′ that is higher than the top surface of the frame 170. In such an embodiment, the polymer seal 175 may be laminated or coated on the force concentrator pattern 300. In such an embodiment, the force concentrator pattern 300 may be formed by a polymer seal 175. In some embodiments, the thickness of the force concentrator pattern 300 is, for example, from about 0.01 mm to about 0.025 mm, from about 0.025 mm to about 0.05 mm, from about 0.05 mm to about 0.1 mm, about 0.1 mm to about 0.2 mm, about 0.2 mm to about 0.3 mm, about 0.025 mm to about 0.1 mm, about 0.025 mm to about 0.2 mm, about 0.025 mm to about 0.254 mm, about 0.025 mm to about 0.3 mm, about 0.05 mm to about 0.1 mm, about 0.05 mm to about 0.2 mm, about 0.05 mm to about 0.3 mm, about 0.1 mm to about 0.2 mm, or It may be about 0.1 mm to about 0.3 mm. In some implementations, the force concentrator pattern 300 may be on either the frame 170 or the base 180, or on both the frame 170 and the base 180. In some implementations, the force concentrator pattern 300 may be on the surface of the frame 170 facing the base 180 and / or on the surface of the base 180 facing the frame 170. In some embodiments, the force concentrator pattern 300 may be on the surface of the frame 170 facing the base 180 of an adjacent cell and / or of the base 180 facing the frame 170 of an adjacent cell. It may be applied to the surface. In some implementations, the force concentrator pattern 300 may be both the frame 170 and / or the surface of the base 180. In some implementations, the thickness of the force concentrator pattern 300 may be substantially the same as the thickness of the frame 170 and / or the base 180.

  [058] As shown in FIGS. 6 and 7, in some embodiments, the force concentrator pattern 300 spans the elongate body 173 of the frame 170 and further partially includes the first end 171 and / or It may extend across the second end 172 of the frame 170. The force concentrator pattern 300 may be designed such that the compressed area across the frame 170, eg, the length of the frame 170, is generally or entirely continuous or uniform. In some embodiments, the force concentrator pattern 300 may extend from the high pressure zone 200 to the outer edge of the frame 170. In some embodiments, the force concentrator pattern 300 may be narrower than the width of the elongated body 173 of the frame 170. For example, the force concentrator pattern 300 may or may not extend from the inner edge of the frame 170 to the outer edge of the frame 170. In some embodiments, the compressed area of the frame 170, the surface area of the force concentrator pattern 300, and the surface area of the sealing surface of the polymer seal 175 may be substantially the same. The design of the force concentrator pattern 300 allows the compression pressure to be generally uniform or constant across the compressed regions of the sealing surfaces of the frame 170 and the polymer seal 175. In some embodiments, reducing the surface area of the force concentrator pattern 300, for example in the first end 171 and / or the second end 172, compresses the sealing surfaces of the frame 170 and the polymer seal 175. The uniformity or flatness of the compression pressure across the region can be increased.

FIG. 8 shows an exemplary embodiment of a bipolar plate 160 in which the frame 170 has a force concentration pattern 300. When a compressive load is being applied to the frame 170 and / or the base 180, the applied compression pressure will be across the compressed area of the force concentrator pattern 300 of the frame 170, the sealing surface of the frame 170 and / or the polymer seal 175. , It may be distributed uniformly throughout. The compressed region over the length of the frame 170 is about 2 cm ² / cm to about 4 cm ² / cm, about 2 cm ² / cm to about 6 cm ² / cm, about 2 cm ² / cm to about 8 cm ² / cm, about 2 cm. from ² / cm to about 10cm ² / cm, from about ^4cm 2 / ^cm about ^6cm 2 / ^cm, from about ^4cm 2 / ^cm about ^8cm 2 / ^cm, about ^4cm 2 / ^cm from about 10cm ² / cm, about ^5cm 2 / It can range from cm to about 7 cm ² / cm, from about 6 cm ² / cm to about 8 cm ² / cm, from about 6 cm ² / cm to about 10 cm ² / cm. In some embodiments, the repetitive distance between the intermediate port 220 and / or the low pressure port 230 can range from about 1 cm to about 3 cm. In some embodiments, the length of the frame 170 and / or the base 180 is about 15 cm to about 30 cm, about 15 cm to about 50 cm, about 15 cm to about 80 cm, about 15 cm to about 100 cm, about 30 cm to about 50 cm, about It can range from 30 cm to about 80 cm, from about 30 cm to about 100 cm, from about 50 cm to about 80 cm, from about 50 cm to about 100 cm, or from about 80 cm to about 100 cm. In some embodiments, the width of the frame 170 and / or the base 180 is about 5 cm to about 10 cm, about 10 cm to about 20 cm, about 20 cm to about 30 cm, about 5 cm to about 20 cm, about 5 cm to about 30 cm, about 10 cm. To about 30 cm, or about 20 cm to about 30 cm.

[060] In some embodiments, the compressed area of the frame 170, the surface area of the force concentrator pattern 300, and / or the surface area of the sealing surface of the polymeric material 175 is about 50 cm ² to about 100 cm ² , about 100 cm ² to about 200 cm ² , about 200 cm ² to about 300 cm ² , about 300 cm ² to about 400 cm ² , about 400 cm ² to about 500 cm ² , about 500 cm ² to about 600 cm ² , about 600 cm ² to about 700 cm ² , about 700 cm ² from about 800 cm ^2, from about 800 cm ² to about 900 cm ^2, about 900 cm ² to about 1000 cm ^2, from about 1000 cm ² to about 1100 cm ^2, about 1100 cm ² to about 1200 cm ^2, about 1200 cm ² to about 1300 cm ^2, or about 1300 cm ² It can range from about 1400 cm ^2, or about 1400 cm ^2, about 1500 cm ^2. In some embodiments, the generally uniform compression pressure distributed along the compressed region of the sealing surface of frame 170 and / or polymer seal 175 is from about 5,000 psig to about 10,000 psig, about 5, 000 psig to about 20,000 psig, about 5,000 psig to about 30,000 psig, about 5,000 psig to about 40,000 psig, about 10,000 psig to about 40,000 psig, about 10,000 psig to about 30,000 psig, about 10,000 It can range from 000 psig to about 20,000 psig, from about 20,000 psig to about 30,000 psig, from about 20,000 psig to about 40,000 psig, or from about 30,000 psig to about 40,000 psig.

[061] FIG. 9 illustrates that when utilizing a force concentrator pattern 300 as described herein, a generally uniform compression pressure is distributed across the compressed regions of the sealing surfaces of the frame 170 and the polymer seal 175. An example is given. The magnitude of the compression pressure is indicated by the hatched density. In FIG. 9, the uniform density of the diagonal lines indicates that the size of the compression pressure over the compressed region of the frame 170 is uniform overall. As shown in FIG. 9, the force concentrator pattern 300 reduces the compressed area at the first end 171 of the frame 170 and thus extends across the first end 171 and the elongated body 173 of the frame 170. The existing compressed area can be made substantially constant, resulting in an overall uniform or even distribution of compression pressure over the compressed areas of the sealing surfaces of the frame 170 and the polymer seal 175. In some embodiments, for example, if the compression load is about 1,000,000 pounds, the area of the force concentrator pattern 300 and the compression area of the frame 170 may be about 50 inches ² , and thus the compression pressure May be about 20,000 psig across frame 170. This substantially uniform or even distribution of compression pressure can reduce or prevent the possibility of fluid leakage from the high pressure zone 200. In some embodiments, the variation in compression pressure across the compressed region of the sealing surface of frame 170 and / or polymer seal 175 is about 2% or less, about 5% or less, about 8% or less, about 10% or less, It may be about 15% or less, or about 20% or less.

  [062] In some embodiments, the force concentrator pattern 300 may be discontinuous across the frame 170. For example, force concentrator pattern 300 may include separate portions at the corners of frame 170. For example, as shown in FIG. 10, corner portion 310 may be a similarly raised surface added to frame 170 as part of force concentrator pattern 300. The corner portion 310 can be made by chemical etching or machining of the frame 170 in the same manner as the force concentrator pattern 300. The corner portion 310 may have the same thickness as the force concentrator pattern 300. In some implementations, the surface area of the force concentrator pattern 300 can be reduced by adding corner portions 310 to the frame 170. In some embodiments, the corner portion 310 and the force concentrator pattern 300 together can make the compressed region of the frame 170 and the sealing surface 175 substantially continuous, thus reducing the compression pressure to the frame. It can be distributed uniformly or evenly over 170.

  [063] In some embodiments, the force concentrator pattern 300 may be formed in the polymer seal 175. For example, the polymer seal 175 may have a thicker thickness over the force concentrator pattern 300 and a thinner thickness over other regions. In some implementations, force concentrator pattern 300 may be an integrated part of frame 170 and / or base 180. In some embodiments, force concentrator pattern 300 may be on a selected surface of frame 170 and / or base 180, or on both surfaces. In some embodiments, each EHC cell in the EHC stack may have a force concentrator pattern 300.

  [064] In some implementations, the use of the force concentrator pattern 300 can reduce requirements regarding the amount of compressive load applied to the frame 170 and the base 180. The reduced requirements for compressive loads can result in reduced requirements for the material of the frame 170 and the base 180, allowing a wide selection of materials used for the frame 170 and the base 180. In some implementations, the frame 170 and the base 180 may be formed of the same material, or may be formed of different materials. The frame 170 and the base 180 are formed of a metal such as stainless steel, titanium, aluminum, nickel, iron, or a metal alloy such as nickel chrome alloy, nickel-tin alloy, inconel, monel, hastelloy, or a combination thereof. It may be. In some embodiments, the frame 170 is also formed of a polymer, composite material, ceramic, or any material capable of withstanding compressive loads, forces and / or pressures applied to the EHC cell or EHC stack during assembly. It may be.

  [065] In some embodiments, the frame 170 and base 180 may include a cladding material, such as stainless steel and clad aluminum, in one or more regions. Cladding can provide the advantages of both metals, for example, in the case of bipolar plates made from stainless steel-clad aluminum, stainless steel protects the aluminum core from corrosion during cell operation, while Provides excellent material properties of aluminum such as high weight specific strength, high thermal conductivity, and high conductivity. In some embodiments, the frame 170 can include anodized, sealed, and primed aluminum. In some embodiments, the frame 170 can include chromated and spray coated aluminum.

  [066] In some embodiments, the frame 170 may be formed of a composite material such as carbon fiber, graphite, glass reinforced polymer, and thermoplastic composite material. In some embodiments, the frame 170 may be formed of a metal that is coated to prevent both corrosion and electrical conduction. According to various embodiments, the frame 170 may be entirely non-conductive, reducing the risk of short circuits between electrochemical cells. Base 180 may be formed of one or more materials that provide corrosion resistance in addition to conductivity during cell operation. For example, the base 180 may be designed to be conductive in areas where active cell elements are located (eg, flow structures, MEAs, etc.).

  [067] Considered in selecting the material and geometry of the elements (eg, polymer seal 175, first seal 240, second seal 250, third seal 260, frame 170, and base 180). Factors and characteristics expected to include at least the design of the force concentrator pattern 300, compression load conditions, material compatibility, sealing pressure conditions, material costs, manufacturing costs, and ease of manufacturing. Can do. The various materials suitable for the force concentration pattern 300 described herein allow for the selection of cheaper materials and manufacturing at lower costs. For example, a lower cost product, plastic (partially listed herein), is replaced with a polymer seal (eg, polymer seal 175, first seal 240, second seal 250, and third seal). It can be used for the seal 260). In addition, multi-element bipolar plates can be expensive to manufacture because they require the use of conventional high-cost milling due to complex details on the plates. Utilizing polymer seal 175 and force concentrator pattern 300 as described herein can reduce the cost and complexity of manufacturing bipolar plates 150 and 160. For example, the frame 170 and base 180 may be manufactured with the force concentrator pattern 300 so that the use of the polymer seal 175 and the generally uniform compression pressure distribution along the sealing surface of the polymer seal 175 is achieved. By enabling, the thickness, manufacturing cost, and manufacturing complexity of the bipolar plates 150 and 160 can be reduced.

  [068] The features described herein can also be used to seal other elements of an electrochemical cell and / or can be used for cells that do not employ a cascade seal arrangement. It is understood that it can be done.

  [069] Other embodiments of the present disclosure are expected to be apparent to those skilled in the art from consideration of the specification and practice of the disclosure of the invention as described herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and essence of the disclosure being indicated by the following claims.

100 Electrochemical Cell 110 Anode 120 Cathode 130 Proton Exchange Membrane (PEM)
140 Membrane electrode assembly (MEA)
150, 160 Bipolar plate 170 Frame 171 First end 172 Second end 173 Elongated body 175 Polymer seal, polymer material, sealing surface 178 Channel 180 Base 190 Void 200 High pressure zone 202 Medium pressure zone 204 Low pressure zone 210 High pressure port 212 First Fluid 214 Second Fluid 216 Third Fluid 220 Medium Pressure Port 230 Low Pressure Port 240 First Seal 250 Second Seal 260 Third Seal 300 Force Concentrator Pattern, Force Concentration Pattern 300 ′ Surface 310 Corner part

Claims (20)

A bipolar plate assembly including a frame and a base,
At least one of the frame and the base has a shape of a force concentrator pattern or has a first surface that includes a force concentrator pattern, the force concentrator pattern partially extending over the first surface Including a raised surface that extends in a general manner;
The surface area of the force concentrator pattern over the length of the frame or the base is generally constant so that the length of the frame and / or the base when the bipolar plate assembly is under compression. A bipolar plate assembly as described above that produces a uniform compression pressure along the same. The bipolar plate assembly of claim 1, wherein a surface area of the force concentrator pattern over the length of the frame or the base ranges from about 2 cm ² / cm to about 10 cm ² / cm.   The bipolar plate assembly of claim 1, further comprising at least one seal assembly between the frame and the base.   The bipolar plate assembly of claim 3, wherein the seal assembly is an elastomeric seal or a polymer seal.   The bipolar plate assembly of claim 3, wherein the compression pressure on the seal assembly is uniformly distributed throughout the seal assembly when the bipolar plate assembly is under compression.   The bipolar plate assembly according to claim 1, wherein the frame and the base are two pieces connected together or one integrated part.   7. The bipolar plate assembly according to claim 6, wherein at least one of the frame and the base is laminated with a polymer material on the top and / or bottom or coated with a polymer film.   8. The compression pressure on the polymer material or the polymer film is evenly distributed throughout the frame and / or the base when the bipolar plate assembly is under compression. Bipolar plate assembly.   The bipolar plate assembly of claim 2, wherein the bipolar plate assembly is at least one of a plurality of bipolar plate assemblies that form an electrochemical stack.   The bipolar plate assembly of claim 2, wherein the compression pressure is in the range of 5,000 psig to 40,000 psig.   The bipolar plate assembly of claim 2, wherein the thickness of the force concentrator pattern ranges from 0.025 mm to the thickness of the frame and / or the base.   The bipolar plate assembly of claim 2, wherein at least one of the frame and the base has a second surface that includes the force concentrator pattern. A method of assembling a bipolar plate assembly comprising:
Compressing the frame and base of the bipolar plate assembly;
Including
At least one of the frame and the base has a shape of a force concentrator pattern or has a first surface that includes a force concentrator pattern, the force concentrator pattern partially extending over the first surface Including a raised surface that extends
The surface area of the force concentrator pattern over the length of the frame or the base is generally constant so that the length of the frame and / or the base when the bipolar plate assembly is under compression. A method as described above, which produces a uniform compression pressure along. The method of claim 13, wherein a surface area of the force concentrator pattern over the length of the frame or the base ranges from about 2 cm ² / cm to about 10 cm ² / cm.   The method of claim 13, wherein the bipolar plate assembly includes at least one seal assembly between the frame and the base.   The method of claim 15, wherein the seal assembly is an elastomeric seal or a polymer seal.   The method of claim 15, wherein the compression pressure on the seal assembly is uniformly distributed throughout the seal assembly when the bipolar plate assembly is under compression.   The method of claim 15, wherein the compression pressure on the seal assembly is greater than the yield strength of the material of the seal assembly. The frame and the base are two pieces connected together or one integrated part;
At least one of the frame and the base is laminated with a polymer material on the top and / or bottom or coated with a polymer film;
14. The compression pressure on the polymeric material or the polymeric film is distributed generally uniformly across the frame and / or the base when the bipolar plate assembly is under compression. Method. An electrochemical cell comprising a pair of bipolar plate assemblies and a membrane electrode assembly disposed between the pair of bipolar plate assemblies,
At least one of the bipolar plate assemblies includes a frame and a base;
At least one of the frame and the base has a shape of a force concentrator pattern or has a first surface that includes a force concentrator pattern, the force concentrator pattern partially extending over the first surface Including a raised surface that extends
The surface area of the force concentrator pattern over the length of the frame or the base is generally constant, thereby along the length of the frame and / or base when the bipolar plate assembly is under compression. Electrochemical cell that produces a uniform compression pressure.

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