KR20180053401A - Bipolar plate with force concentrator pattern - Google Patents

Abstract

Embodiments herein relate to bipolar plate assemblies. The bipolar plate assembly includes a frame and a base. Wherein at least one of the frame and the base has a shape of a force concentrator pattern or has a first surface including a force concentrator pattern, the force concentrator pattern includes a raised surface partially extending over the first surface do. The surface area of the force concentrator pattern across the length of the frame or base is substantially constant to produce a uniform compressive force along the length of the frame and / or base when the bipolar plate assembly is under compression.

Description

Bipolar plate with force concentrator pattern

This application claims the benefit of U.S. Provisional Patent Application No. 62 / 221,276, filed September 21, 2015, which is incorporated herein by reference in its entirety.

The present specification relates to a bipolar plate, and more particularly to a bipolar plate having a force concentrator pattern.

Electrochemical cells, which are typically classified as fuel cells or electrolytic cells, are devices that are used to generate currents from chemical reactions or to induce chemical reactions using current flow. Fuel cells convert the chemical energy of a fuel (for example, hydrogen, natural gas, methanol, gasoline, etc.) and an oxidant (air or oxygen) into electricity, heat and water waste. A basic fuel cell includes a negatively charged anode, a positively charged cathode, and an ion conductive material, referred to as an electrolyte.

Various fuel cell technologies use different electrolyte materials. Proton exchange membrane (PEM) fuel cells use a polymeric ion conductive membrane as an electrolyte, for example. In hydrogen PEM fuel cells, hydrogen atoms can be electrochemically separated from the anode to electrons and protons (hydrogen ions). The electrons flow through the circuit to the cathode and generate electricity, while the proton diffuses through the electrolyte membrane to the cathode. At the cathode, hydrogen protons react with electrons and oxygen (supplied to the cathode) to produce water and heat.

An electrolytic cell refers to a fuel cell that operates inversely. A basic electrolytic cell can function as a hydrogen generator by decomposing water into hydrogen and oxygen gas when external potential is applied. The basic techniques of a hydrogen fuel cell or an electrolytic cell can be applied to electrochemical hydrogen operation such as electrochemical hydrogen compression, refining or expansion.

An electrochemical hydrogen compressor (EHC) can be used, for example, to selectively deliver hydrogen from one side of the cell to the other. The EHC may comprise a proton exchange membrane sandwiched between a first electrode (i.e., an anode) and a second electrode (i.e., cathode). The hydrogen-containing gas can be in contact with the first electrode, and the potential difference can be applied between the first electrode and the second electrode. At the first electrode, the hydrogen molecule can be oxidized and the reaction can produce two electrons and two protons. Two protons are electrochemically driven through the membrane to the second electrode of the cell where the two paths are recombined and reduced by electrons rerouted to form hydrogen molecules. The reaction occurring at the first electrode and the second electrode can be represented by the chemical reaction formula shown below.

A first electrode oxidation ^{_{reaction: H 2 → 2H + + 2e}} -

Second electrode reduction reaction: 2H ⁺ + 2e ^- ? H ₂

Overall electrochemical reaction: H ₂ → H ₂

EHCs operating in this manner are often referred to as hydrogen pumps. When the hydrogen stored in the second electrode is confined to a limited space, the electrochemical cell compresses hydrogen or increases the pressure. The maximum pressure or flow rate that an individual cell can make may be limited depending on the battery design. To achieve greater compression or higher pressure, multiple cells may be connected in series to form a multi-stage EHC. In multi-stage EHC, the gas flow path may be configured, for example, such that the compressed output gas of the first cell is the input gas of the second cell. Alternatively, single stage cells may be connected in parallel to increase the throughput capacity of the EHC (i.e., the total gas flow rate). In both single stage and multi-stage EHC, the cells may be stacked, and each cell may comprise a cathode, an electrolyte membrane and an anode. Each cathode / membrane / anode assembly typically comprises a "membrane electrode assembly" or "MEA" supported on both sides by bipolar plates.

The bipolar plate can provide mechanical support for the EHC and physically separate the individual cells in a stack while electrically connecting them. The bipolar plate may provide a high pressure zone where reactants or fuels, such as hydrogen, accumulate. In addition, the bipolar plate can act as a collector / conductor and can provide a passageway for reactants or fuel. Typically, the bipolar plate is made of a metal, for example stainless steel, titanium or the like, and a non-metallic electrical conductor, for example graphite.

Hydrogen compressors or hydrogen pumps typically have accumulated hydrogen at a second electrode limited to a high pressure zone formed by a bipolar plate. Also, the pressure may increase as more and more hydrogen is formed and accumulated in the high-pressure zone. To improve safety and energy efficiency by reducing the likelihood of hydrogen leakage, the high pressure zone may be sealed by 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 seal in the high pressure zone. The seal may comprise an annular seal extending along the periphery of the high pressure zone and / or may comprise a polymeric film coated or laminated to the surface of one or more bipolar plates.

A sufficient and generally even compressive force needs to be applied to the seal between the bipolar plates. The applied minimum compressive force may be at least the yield strength of the sealing material so that the material of the sealing portion deforms to create a sealing surface. In some embodiments, the minimum compressive force may be less than the yield strength of the material. If the compressive force is generally uneven or uneven across the sealing surface, minimal compressive forces may not be applied to some areas on the sealing surface, which may cause leakage of reactants or fuel to such areas. Current options for preventing or reducing the likelihood of leakage due to the non-uniform compressive force applied to the seal include applying a high compressive load to the bipolar plate such that a minimum compressive force is applied across the sealing surface. However, applying a high compressive load not only on the sealing surface, but also on the portions of the bipolar plate, where minimal compressive forces have already been applied and may not be able to sustain high compressive forces, can result in high compressive forces. Thus, high compressive loads result in stricter requirements for bipolar plate materials and / or other components of the EHC or EHC stack, including, for example, material compatibility, material strength, material cost, manufacturing cost and ease of manufacture . Thus, there is a growing need for bipolar plate assemblies that are able to distribute a more uniform and / or even compressive force across the sealing surface and / or across the bipolar plate.

One aspect of the invention relates to a bipolar plate assembly. The bipolar plate assembly may include a frame and a base. At least one of the frame and the base may be in the form of a force concentrator pattern or may comprise a first surface. The first surface may include a force concentrator pattern that may include a raised surface that extends partially across the first surface. The surface area of the force concentrator pattern across the length of the frame or base is generally constant such that a uniform compressive force can be produced along the length of the frame and / or base when the bipolar plate assembly is under compression.

Another aspect of the disclosure relates 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 be in the form of a force concentrator pattern or may comprise a first surface. The first surface may include a force concentrator pattern that 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 substantially constant. The method may further comprise producing a uniform compressive force along the length of the frame and / or the base when the bipolar plate assembly is under compression.

Another aspect of the disclosure relates to an electrochemical cell. The electrochemical cell may include a pair of bipolar plates and a membrane electrode assembly positioned between the pair of bipolar plates. At least one of the bipolar plates may be in the form of a force concentrator pattern or may comprise a first surface. The first surface may include a force concentrator pattern that may include a raised surface that extends partially over the first surface. The surface area of the force concentrator pattern across the length of the frame or base may be generally constant. The method may further comprise producing a uniform compressive force along the length of the frame and / or the base when the bipolar plate assembly is under compression.

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 invention, as claimed.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 is an exploded side view of a portion of an electrochemical cell showing various components of an electrochemical cell according to an exemplary embodiment.
Figure 2 is a perspective view of a base and a frame of a bipolar plate assembly in accordance with an exemplary embodiment.
3 is a perspective view of a base and frame of a bipolar plate assembly in accordance with an exemplary embodiment.
4 is a top view of a frame of an exemplary bipolar plate assembly.
5 is a top view of a frame of an exemplary bipolar plate assembly.
6 is a perspective view of a frame of a bipolar plate assembly in accordance with an exemplary embodiment;
7 is an enlarged view of a frame of a bipolar plate assembly in accordance with an exemplary embodiment.
8 is a perspective view of a base and a frame of a bipolar plate assembly in accordance with an exemplary embodiment.
9 is a top view of a frame of a bipolar plate assembly in accordance with an exemplary embodiment.
10 is a perspective view of a frame of a bipolar plate assembly in accordance with an exemplary embodiment;

Hereinafter, representative embodiments of the present invention will be described in detail with reference to the embodiments 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 in the context of an electrochemical cell for compressing hydrogen, the apparatus and method of the present invention may be used with various types of fuel cells and electrochemical cells, including, but not limited to, electrolytic cells, hydrogen purifiers, Can be used.

1 shows 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 combined anode 110, cathode 120 and PEM 130 may comprise a membrane electrode assembly (MEA) 140. The PEM 130 may comprise a pure polymer membrane or composite membrane, and in the case of a composite membrane, for example, silica, heteropoly acid, layered metal phosphate, phosphate and zirconium phosphate may be embedded in the polymer matrix. The PEM 130 can transmit protons but does not conduct electrons. The anode 110 and the cathode 120 may comprise porous carbon electrodes containing a catalyst layer. Catalytic materials, such as platinum, can increase the reaction rate of reactants or fuels.

The electrochemical cell 100 may further include two bipolar plates 150 and 160. The bipolar plates 150, 160 may serve as support plates, conductors, provide a passage for each electrode surface for reactants or fuel, and provide a path for the removal of the compressed reactant or fuel. The bipolar plates 150, 160 may also include access channels for cooling fluid (i.e., water, glycol, or water-glycol mixture). The bipolar plates 150 and 160 can separate the electrochemical cell 100 from neighboring cells in an electrochemical stack (not shown). In some embodiments, the bipolar plates 150 and / or 160 may function as bipolar plates for two neighboring cells such that each side of the bipolar plates 150 and 160 is in contact with a different MEA 140 have. For example, the plurality of electrochemical cells 100 may be connected in series to form a multi-stage electrochemical hydrogen compressor (EHC) or may be stacked in parallel to form a single stage EHC.

In operation, according to an exemplary embodiment, hydrogen gas may be supplied to the anode 110 via the bipolar plate 150. The 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. [ The hydrogen in the anode 110 can be oxidized to divide hydrogen into electrons and protons. While the electrons are redirected around the PEM 130, the protons are electrochemically transported, or "pumped" through the PEM 130. In the cathode 120 on the opposite side of the PEM 130, the transported protons and redirected electrons are reduced to form hydrogen. As more and more hydrogen is formed in the cathode 120, hydrogen can be compressed and pressed within the high pressure zone created in the bipolar plate 160.

In some embodiments, each bipolar plate 150 and 160 may be formed of two parts or components. 2 illustrates one embodiment of a bicomponent bipolar plate 160 in which the bipolar plate 160 includes a frame 170 and a base 180. In one embodiment, The frame 170 may define a cavity 190 in fluid communication with the flow structure (not shown) of the base 180. In some embodiments, the frame 170 and the base 180 may be formed as one integrated portion or component. Although the following description refers to the bipolar plate 160, this disclosure is equally applicable to the bipolar plate 150 as well.

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 another shape, e.g., square, "race-track" (e.g., a substantially rectangular shape with semi-elliptical sides ), Circular, oval, elliptical, or other shapes. The shape of the frame 170 and the base 180 may correspond to other components of the electrochemical cell 100 (e.g., cathode, anode, PEM, flow structure, etc.) or an electrochemical cell stack.

The frame 170 and the base 180 may be configured for coplanar coupling. The frame 170 and the base 180 may be releasably coupled or fixedly coupled together, or may be an integral portion. For example, one or more attachment methods can be used including bonding, welding, brazing, soldering, diffusion bonding, ultrasonic welding, laser welding, stamping, riveting, resistance welding and / or sintering. In some embodiments, the binder may comprise an adhesive. Suitable adhesives include, for example, binders, epoxies, cyanoacrylates, thermoplastic sheets (including thermally adhered thermoplastic sheets), urethane, anaerobic adhesives, UV curing and other polymers. In some embodiments, the frame 170 and the base 180 may be joined by a friction fit. For example, one or more seals between components can create an appropriate frictional force between the components upon compression to prevent unintentional slippage.

In some embodiments, the frame 170 and the base 180 may be releasably coupled using fasteners, e.g., screws, bolts, clips, or other similar mechanisms. In some embodiments, compression rods and nuts can pass through the bipolar plates 150 and 160 or along the exterior so that the electrochemical cell 100 or the plurality of electrochemical cells 100 can be in one May be used to compress frame 80 and base 70 together as they are compressed into a stack of layers.

In some embodiments, the frame 170 and the base 180 may help define a plurality of different pressure zones, for example, a plurality of seals may define one or more different pressure zones. A plurality of different seals and pressure zones according to one embodiment are shown in Fig. The plurality of seals may include a first seal portion 240, a second seal portion 250, and a third seal portion 260. The first seal portion 240 can be completely contained in the second seal portion 250 and the second seal portion 250 can be completely contained in the third seal portion 260. [ This arrangement of the seals (e.g., one within the other) may be categorized into a cascade seal configuration. The cascade sealing arrangement can provide several advantages. For example, the cascade sealing arrangement can limit the likelihood of high pressure hydrogen exiting the electrochemical cell 100 by providing sealing redundancy in the form of multiple sealing protective layers. Reducing the likelihood of hydrogen leakage can be beneficial to safety and energy efficiency. In addition, the cascade sealing arrangement may allow for self-regulation of pressure by allowing high pressure bleeding from the high pressure zone to the low pressure zone.

The shapes of the first sealing portion 240, the second sealing portion 250 and the third sealing portion 260 may generally correspond to the shapes of the bipolar plates 150 and 160 as shown in FIG. The first seal 240 acting as a high pressure seal can be configured to receive a first fluid 212 (e.g., hydrogen) within the high pressure zone 200 defining a portion of the high pressure zone 200 have. The first seal 240 may range at least the outer boundary of the high pressure zone 200 between the frame 170 and the base 180. The high pressure region 200 may include one or more flow structures (not shown), e.g., a combination of the frame 170 and the base 180, or the frame 170 and the base 180 may be formed as one integrated portion The cathode flow structure and the anode flow structure that extend through the cavity 190 when they are in contact with each other.

The first fluid 212, e.g., hydrogen, may be generated in the cathode 120 and accumulated in the high-pressure region 200, and the connection between the frame 170 and the base 180 may be sealed by the first seal 240 . The hydrogen in the high pressure zone 200 can be compressed and as a result the pressure can increase as more and more hydrogen is produced and collected in the high pressure zone 240. The hydrogen in the high pressure zone 200 may be compressed to a pressure in excess of, for example, about 10,000 psig, about 15,000 psig, about 20,000 psig, about 25,000 psig, about 30,000 psig, or about 35,000 psig.

As shown in FIG. 2, the first seal 240 may be configured to extend around the outside of the high pressure ports 210. The high pressure port 210 may be configured to supply or discharge the first fluid 212 in the high pressure region 200. The high pressure port 210 may be in fluid communication with the high pressure port of adjacent electrochemical cells in a multiple cell electrochemical compressor. The high pressure port 210 may be in fluid communication with a cathode flow structure (not shown) that may be located above the base 180 that extends through the cavity 190.

In some embodiments, the second seal portion 250 may define the outer perimeter of the intermediate pressure region 202. The intermediate pressure zone 202 may be defined 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 configured to include a second fluid 214. Sectional area and volume of the intermediate pressure zone 202 can be variously modified based on the geometry of the frame 170, the base 180, the first seal 240 and the second seal 250. [ The intermediate pressure zone 202 further includes one or more intermediate pressure ports 220 to be in fluid communication therewith. The intermediate pressure port 220 may be configured to discharge the second fluid 214 contained in the intermediate pressure zone 202. The intermediate pressure port 220 may be in fluid communication with an anode flow structure (not shown) that may be located on top of the cathode flow structure extending through the cavity 190.

The shape and number of the intermediate pressure port 220 can be variously changed. For example, intermediate pressure port 220 may be square, rectangular, triangular, polygonal, circular, elliptical or other shape. The number of intermediate pressure ports 220 may vary from 1 to 25, or more. The intermediate pressure port 220 may be evenly distributed along the length of the frame 170 of the bipolar plate 160 and the base 180, as shown in FIG. In some embodiments, the intermediate pressure port 220 may extend all around the intermediate pressure zone 202.

In some embodiments, the second fluid 214 discharged through the intermediate pressure port 220 may be re-supplied to the electrochemical cell 100. In some embodiments, the second fluid 214 discharged through the intermediate pressure port 220 can be collected and recycled. The second fluid 214 in the intermediate pressure zone 202 may be lower in pressure than the first fluid 212 in the high pressure zone 200. [

In some embodiments, the third seal 260 can be configured to receive the third fluid 216 within the low pressure zone 204 by defining the low pressure zone 204. The low pressure zone 204 can be defined by the second seal 250, the third seal 260, the frame 170 and the base 180. 2, the low pressure zone 204 may extend around the periphery of the intermediate pressure zone 202 separated by the second seal 240. As shown in FIG. The cross-sectional area and volume of the low-pressure area 204 can be varied variously based on the geometry of the frame 170, the base 180, the second seal 240 and the third seal 250. The low pressure zone 204 further includes one or more low pressure ports 230 to be in fluid communication therewith. The low pressure port 230 may be configured to discharge the third fluid 216 collected and / or received within the low pressure zone 204.

The shape and number of the low-pressure port 230 can be variously changed. For example, low pressure port 230 may be square, rectangular, triangular, polygonal, circular, elliptical or other shapes. The number of low pressure ports 230 may vary, for example, from 1 to 50, or more. 2, the low pressure port 230 may be evenly distributed along the length of the bipolar plate 160, spaced between the second seal 240 and the third seal 250. In some embodiments, the low pressure port 230 may extend all around the intermediate pressure zone 204.

In some embodiments, the third fluid 216 discharged through the low pressure port 230 may be re-supplied to the electrochemical cell 100. In some embodiments, the third fluid 216 discharged through the low pressure port 230 can be collected and recycled. The third fluid 216 in the low pressure zone 204 may be lower in pressure than the first fluid 212 in the high pressure zone 200 and the second fluid 214 in the intermediate pressure zone 202.

According to an exemplary embodiment, the first seal 240, the second seal 250 and the third seal 260 may be disposed in different pressure zones of the bipolar plate 160 (e.g., the high pressure zone 200, About 20,000 psig, about 25,000 psig, about 30,000 psig, about 35,000 psig, about 40,000 psig (for example, intermediate pressure zone 202 and low pressure zone 204) for a long period of time , Or a portion of an assembly of sealing components that can withstand pressures in excess of about 40,000 psig to withstand many pressure cycles (e.g., more than 1,000 cycles). For example, the first seal portion 240 may seal the high pressure zone 200 with a pressure in the range of about 25,000 psig to about 40,000 psig and the second seal portion 250 may seal between about 0 psig and about 3,000 psig The third seal 260 may seal the low pressure zone 204 having a pressure in the range of about 0 psig to about 20 psig.

In some embodiments, the bipolar plates 150 and 160 may be configured to form only two pressure zones. For example, the bipolar plates 150 and 160 may be configured such that only the first seal 240 and the third seal 260 form the high pressure zone 200 and the low pressure zone 204, And may be configured to remove the intermediate pressure zone 202. It is also contemplated that, in some embodiments, the bipolar plates 150 and 160 may be configured to have more than three pressure zones formed. For example, the fourth pressure zone may be formed by adding a fourth seal.

Conventionally, an elastomeric seal (e.g., an O-ring) seals a high pressure zone 200, an intermediate pressure zone 202 and / or a low pressure zone 204 created between the frame 170 and the base 180 The second sealing portion 250, and / or the third sealing portion 260 to seal the high-pressure port 210 and to seal the high-pressure port 210. [ Elastomers often cause reliability problems in high-pressure systems. In addition to making the electrochemical cell less durable and resistant, the elastomeric seal needs to be die cut, manually positioned, overmolded, or deposited using an x-y table and then cured. In addition, the elastomeric seal may need to include a gland or groove on the surface of the frame 170 or the base 180. While the elastomeric seal may be bonded into the grooves, they may slip out of place during manufacture, assembly, and / or operation. Because of the uncertainty and complexity of the manufacturing process caused by the elastomeric seal, in some embodiments, the polymeric seal portion may be advantageously used in sealing one or more pressure zones formed between the frame 170 and the base 180. [

The polymeric seal can be applied to the frame 170 and / or the base 180 by a variety of techniques, for example, lamination, spray coating or dip coating. The use of a polymeric seal can reduce the complexity of the bipolar plates 150, 160. For example, glands or grooves on the surface of frame 170 and / or base 180 may be removed. Removal of the gland or groove may result in thinner frame 170 and / or base 180, reducing the amount of required machining and / or manufacturing processes, and providing a seal surface < RTI ID = 0.0 > Thereby reducing the compressive force that frame 170 and / or base 180 must support. In another example, using a polymeric seal allows the frame 170 and base 180 to be formed as a single integrated portion, thereby further reducing the thickness of the bipolar plates 150 and 160. [ In addition, the laminated or spray coated polymeric seal can be securely held in place because it can be tightly bonded to frame 170 and / or base 180. The polymer seal can reduce manufacturing costs by reducing the number of machining cycles of the bipolar plates 150 and 160, lowering the application cost, and reducing the material of the bipolar plates 150 and 160.

3, the polymer seal 175 may be laminated or coated on the surface of, for example, one of the frame 170 and / or the base 180, or both. The polymer seal 175 can be modified to seal the high pressure zone 200, the intermediate pressure zone 202 and / or the low pressure zone 204 when a compressive load is applied to the frame 170 and the base 180 have. The polymer seal 175 may be configured to receive the first fluid 212 within the high pressure region 200 and to receive the second fluid 214 within the intermediate pressure region 202 and / To assist in receiving the third fluid 216 within the first fluid 216. [ 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 sealing surface extending across the compression region between the frame 170 and the base 180 and may have a sealing surface extending from the high pressure zone 200 to the intermediate pressure zone 202 and / As shown in Fig.

In some embodiments, the polymeric seal 175 can be used at the locations of the first seal 240, the second seal 250, and / or the third seal 260. 4, the polymer seal 175 may include a first seal 240 sealing the high pressure zone 200 and a second seal 240 sealing the intermediate pressure zone 202 and the low pressure zone 204, May be used in conjunction with the seal 175. 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 in communication with the first seal 240, the high pressure zone 200 and / And may be made to be in fluid communication with a flow structure (not shown). The polymer seal 175 may include one or more channels 178 to allow the intermediate pressure port 220 to be in fluid communication with the high pressure zone 200.

In some embodiments, the polymer seal 175 may seal different pressure zones and provide a pressure of about 15,000 psig, about 20,000 psig, about 25,000 psig, about 30,000 psig, about 35,000 psig, or about 15,000 psig for a long period of time It can withstand pressures in excess of about 40,000 psig to withstand many pressure cycles (e.g., over 1,000 cycles). For example, the polymeric seal 175 may seal the high pressure zone 200 having a pressure in the range of about 25,000 psig to about 40,000 psig, and may have an intermediate pressure zone 202, and / or may seal the low pressure zone 204 with a pressure in the range of about 0 psig to about 20 psig. This allows the reactants or fuels produced in the cathode 120, e.g., hydrogen, to be highly compressed, for example, in the high-pressure zone 200.

The dimensions of the polymer seal 175, including shape, thickness, and width, may vary and may be based on the dimensions of the electrochemical cell 100 and the bipolar plate 160. The thickness of the polymeric seal 175 may be, 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, 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, From about 0.05 mm to about 0.3 mm, from about 0.1 mm to about 0.2 mm, or from about 0.1 mm to about 0.3 mm. In some embodiments, the polymeric seal 175 may be a separate polymeric film sandwiched between the frame 170 and the base 180. In some embodiments, the polymer seal 175 can be coated or laminated on the frame 170 or the base 180, or both on the frame 170 and the base 180. In some embodiments, a polymeric seal 175 may be applied to the surface of the frame 170 facing the base 180 and / or to 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 an adjacent cell and / or may be applied to a base (e.g., 180). ≪ / RTI > In some embodiments, the polymer seal 175 can be applied to both the frame 170 and / or the base 180 surface. In some embodiments, the frame 170 may be formed of a material of the polymer seal 175 so that the thickness range of the polymer seal 175 is substantially equal to the thickness range of the frame 170. [

In some embodiments, the first seal portion 230, the second seal portion 240, and / or the third seal portion 250 may be fabricated or replaced with the polymer seal portion 175 described herein. 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 polymeric sealing section (175), the first sealing portion 240, a second sealing unit 250 and / or third sealing section 260 include, but are not limited to, Teflon ^TM, Torlon ^®, May be made of a polymeric sealing material including polyetheretherketone (PEEK), polyethyleneimine (PEI), polyethylene terephthalate (PET), polycarbonate (PC), polyimide and polysulfone. The polymeric material may be acid resistant and should not leach any material that is detrimental to the operation of the electrochemical cell 100. In some embodiments, the frame 170 and / or the base 180 may be coated with an adhesive configured to assist sealing. The adhesive may be, for example, a pressure or heat activated adhesive.

When the bipolar plate 160 is assembled, the frame 170 and the base 180 (not shown in FIG. 4) can be connected and the frame 170, the base 180 and the frame 170 and / A compressive force may be applied to the polymer seal 175 applied to the seal 180. In some embodiments, the applied minimum compressive force may be greater than the yield strength of the material of the seal portion 175 to cause the material of the seal portion 175 to deform to create a seal surface. In some embodiments, when the surface of the frame 170 and / or the base 180 to which the polymer seal 175 has been applied is substantially polished to create a sealing surface, the minimum applied compressive force is applied to the polymer seal 175) material yield strength. A sealing surface may be formed in the compression area of the frame 170 and / or the base 180. Although the following description refers to the frame 170, this disclosure is equally applicable to the base 180 as well.

As shown in FIG. 4, for example, a compressed region of the frame 170 may extend over the upper surface of the frame 170. In some embodiments, the frame 170 may have an elongated shape having a first end 171, a second end 172, and an elongate body 173 extending therebetween. 4, the first end 171 and the second end 172 of the frame 170 may be wider in area than the elongate body 173 and the frame 170 may have a larger area than the elongate body 173. In some embodiments, The area compressed along the elongate body 173 of the frame 170 may be smaller or smaller than the compression area at the first end 171 and the second end 172 of the frame 170. [ The compressive area at the first end 171 and the second end 172 of the frame 170 can be increased by increasing the elongation of the frame 170 due to the difference in contact area, A compressive force less than the area compressed along the mold body 173 can be applied. This situation can lead to non-uniform compressive forces across the compression region of the frame 170 and the sealing surface of the polymer seal 175. This may result in fluid leakage at some locations along the sealing surface, e.g., near the first end 171 and the second end 172, which may be less compressive or in some cases may not meet the minimum compressive force.

5 shows an example in which an uneven compressive force is applied to the compression region of the frame 170 and the sealing surface of the polymer seal 175. [ The magnitude of the compressive force is shown by the density of the oblique line. 5, the compressive force applied to the second end 172 of the frame 170 is less than the compressive force applied to the elongated body 173 of the frame 170. As shown in Fig. In this example, when a minimum compressive force is applied to the compression region along the elongate body 173 of the frame 170, a compressive force less than the minimum compressive force is applied to the compression region 172 at the second end 172 of the frame 170, For example, from the high pressure zone 200 to the intermediate pressure zone 202, from the intermediate pressure zone 202 to the low pressure zone 204 or to the outside of the bipolar plate, and / 204 present a potential risk of fluid leaking out of the bipolar plate. Alternatively, if the compressive force applied to the compressive region of the second end 172 of the frame 170 is greater than or equal to the minimum compressive force, then it is applied to the compressive region along the elongated body 173 of the frame 170 The applied compressive force may substantially exceed the maximum compressive force that the material of the frame 170 can tolerate so that rigid design requirements to accommodate this excessive compressive force and / or overdesign of the frame 170 may be required. have.

In order to increase the uniformity of the compression force applied to the frame 170 and / or the compression area of the base 180 and the sealing surface of the polymer seal 175, the frame 170 and / The pattern 300 can be defined. 6, the force concentrator pattern 300 may be a raised surface from the top and / or bottom surface of the frame 170 and / or the base 180. [ For example, the force concentrator pattern 300 can be created by chemically etching or machining the upper surface of the frame 170. [ In some embodiments, the force concentrator pattern 300 may be configured such that the surface profile of the frame 170 and / or the base 180 is substantially identical to the force concentrator pattern 300 and / May be created by machining the base 180 to remove material from the frame 170 and / or the base 180. For example, some of the materials of the frame 170 near the first end 171 and the second end 172 may be removed or etched away to create a force concentrator pattern 300. Although the following description refers to the force concentrator pattern 300 as a raised surface, this description is equally applicable to the force concentrator pattern 300, which is substantially the same as the profile of the frame 170 and / or the base 180 .

As shown in FIG. 7, for example, the force concentrator pattern 300 can be described as a raised surface 300 'on the upper surface of the frame 170. In this embodiment, the polymer seal 175 may be laminated or coated on the force concentrator pattern 300. In this embodiment, the force concentrator pattern 300 may be formed by the 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, from about 0.1 mm to about 0.2 from about 0.025 mm to about 0.2 mm, from about 0.2 mm to about 0.3 mm, from about 0.025 mm to about 0.1 mm, from about 0.025 mm to about 0.2 mm, from about 0.025 mm to about 0.254 mm, from about 0.025 mm to about 0.3 mm, From about 0.05 mm to about 0.2 mm, from about 0.05 mm to about 0.3 mm, from about 0.1 mm to about 0.2 mm, or from about 0.1 mm to about 0.3 mm. In some embodiments, the force concentrator pattern 300 may be on the frame 170 or the base 180, or on both the frame 170 and the base 180. In some embodiments, 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 present on the surface of the frame 170 facing the base 180 of an adjacent cell and / or may be on the base (e.g., 180). ≪ / RTI > In some embodiments, the force concentrator pattern 300 may be present on both sides of the frame 170 and / or the base 180. In some embodiments, 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.

6 and 7, in some embodiments, the force concentrator pattern 300 extends across the elongate body 173 of the frame 170 and extends through the first end 171 and / / RTI > and / or the second end < RTI ID = 0.0 > 172 < / RTI > The force concentrator pattern 300 may be designed such that the compression region over the length of the compression region over the frame 170, for example, the frame 170, may be roughly or substantially constant or substantially 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 compression area of the frame 170, the surface area of the force concentrator pattern 300, and the surface area of the sealing surface of the polymeric seal 175 may be substantially the same. The design of the force concentrator pattern 300 may make the compressive force across the compression region of the frame 170 and the sealing surface of the polymer seal 175 substantially uniform or constant. In some embodiments, for example, reducing the surface area of the force concentrator pattern 300 at the first end 171 and / or the second end 172 may be achieved by compressing the compression region of the frame 170 and the polymer seal 175 can increase the uniformity or puckering of the compression force across the sealing surface.

FIG. 8 shows an exemplary embodiment of a bipolar plate 160 in which frame 170 has a force concentrator pattern 300. If a compressive load is applied to the frame 170 and / or the base 180, the applied compressive force may be applied to the force concentrator pattern 300 of the frame 170, the compression region of the frame 170, and / RTI ID = 0.0 > 175 < / RTI > The area compressed along the length of the frame 170 may range from about 2 cm ² / cm to about 4 cm ² / cm, from about 2 cm ² / cm to about 6 cm ² / cm, from about 2 cm ² / cm to about 8 cm ² / cm, about ² cm 2 / cm to about 10 cm ² / cm, about 4 cm ² / cm to about 6 cm ² / cm, about 4 cm ² / cm to about 8 cm ² / cm, about 4 cm ² / cm to about 10 cm ² / cm, about 5 cm ² / cm to about 7 cm ² / cm, about 6 cm ² / cm to about 8 cm ² / cm, about 6 cm ² / cm to about 10 cm ² / cm. < / RTI > In some embodiments, the repetition distance between intermediate pressure port 220 and / or low pressure port 230 may range from about 1 cm to about 3 cm. In some embodiments, the length of the frame 170 and / or the base 180 is from about 15 cm to about 30 cm, from about 15 cm to about 50 cm, from about 15 cm to about 80 cm, from about 15 cm to about 100 cm From about 30 cm to about 50 cm, from about 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 may range from about 5 cm to about 10 cm, from about 10 cm to about 20 cm, from about 20 cm to about 30 cm, from about 5 cm to about 20 cm From about 5 cm to about 30 cm, from about 10 cm to about 30 cm, or from about 20 cm to about 30 cm.

In some embodiments, the surface area of the sealing surface of the frame 170, the compression zone, the force concentrator pattern 300, the surface area and / or the polymeric material 175 of 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 to about 800 cm ^2, about 800 cm ² to about 900 cm ^2, about 900 cm ² to about 1000 cm ^2, about 1000 cm ² to about 1100 cm ^2, about 1100 cm ² To about 1200 cm ² , from about 1200 cm ² to about 1300 cm ² , from about 1300 cm ² to about 1400 cm ^2, or from about 1400 cm ² to about 1500 cm ² . In some embodiments, the substantially uniformly distributed compressive forces along the compression region of the frame 170 and / or the sealing surface of the polymeric seal 175 can range from about 5,000 psig to about 10,000 psig, from about 5,000 psig to about 20,000 psig, From about 5,000 psig to about 30,000 psig, from about 5,000 psig to about 40,000 psig, from about 10,000 psig to about 40,000 psig, from about 10,000 psig to about 30,000 psig, from about 10,000 psig to about 20,000 psig, from about 20,000 psig to about 30,000 psig, To about 40,000 psig or from about 30,000 psig to about 40,000 psig.

9 illustrates an example in which compressive forces are distributed substantially uniformly over the compression area of the frame 170 and the sealing surface of the polymer seal 175 when using the force concentrator pattern 300 described herein. The magnitude of the compressive force is shown by the density of the oblique line. The uniform density of the oblique lines in Fig. 9 indicates that the magnitude of the compressive force over the compression region of the frame 170 is substantially uniform. 9, since the force concentrator pattern 300 reduces the compression area at the first end 171 of the frame 170, the first end 171 of the frame 170 and the elongated body 173 ) To substantially uniformly or evenly distribute the compressive force over the compression area of the frame 170 and the sealing surface of the polymer seal 175. In some embodiments, for example, given a compressive load of about 1,000,000 pounds, the area of the force concentrator pattern 300 and the compressive area of the frame 170 may be about 50 in ² , 170). ≪ / RTI > This substantially uniform or evenly distributed compressive force may reduce or prevent the possibility of fluid leaking in the high pressure zone 200. In some embodiments, the variability of the compressive force across the compression region of the frame 170 and / or the sealing surface of the polymeric seal 175 is about 2%, about 5%, about 8%, about 10%, about 15% May not exceed about 20%.

In some embodiments, the force concentrator pattern 300 may not be continuous across the frame 170. For example, the force concentrator pattern 300 may include separate portions at the corners of the frame 170. For example, as shown in FIG. 10, the corner portion 310 may be a similarly raised surface added to the frame 170 as part of the force concentrator pattern 300. The corner portion 310 can be created by chemically etching or machining the frame 170 in the same manner as the force concentrator pattern 300. The thickness of the corner portion 310 may be equal to the thickness of the force concentrator pattern 300. In some embodiments, the surface area of the force concentrator pattern 300 can be reduced by adding a corner portion 310 to the frame 170. [ In some embodiments, the corner portion 310 and the force concentrator pattern 300 together make the compression region of the frame 170 and the sealing surface 175 approximately constant, and therefore compressive forces are applied across the frame 170 Generally, it distributes uniformly or evenly.

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

In some embodiments, the use of the force concentrator pattern 300 may reduce the requirements for the compressive weight applied to the frame 170 and the base 180. The reduced requirements for the compressive load can reduce the requirements for the material of the frame 170 and the base 180, thereby enabling a wide selection of materials to be used for the frame 170 and the base 180. In some embodiments, the frame 170 and the base 180 may be formed of the same material or different materials. The frame 170 and the base 180 may be formed of a metal such as stainless steel, titanium, aluminum, nickel, iron or the like or a metal alloy such as a nickel chromium alloy, a nickel-tin alloy, Inconel, Monel, Hastelloy, . In some embodiments, the frame 170 may be formed of any material capable of handling the compressive load, force, and / or pressure applied to the polymer, composite, ceramic, or EHC cell or EHC stack upon assembly.

In some embodiments, the frame 170 and the base 180 may comprise a material that is clad, for example, aluminum coated with stainless steel on one or more areas. Cladding can provide the advantage of two metals, for example, in the case of bipolar plates made of stainless steel coated aluminum, stainless steel protects the aluminum core from corrosion while the cell is operating, while high strength to weight ratio , High thermal conductivity and electrical conductivity, and the like. In some embodiments, the frame 170 may include aluminum that is anode oxidized, sealed, and primed. In some embodiments, the frame 170 may comprise chromium-plated and spray-coated aluminum.

In some embodiments, the frame 170 may be formed of a composite material, such as carbon fibers, graphite, glass reinforced polymers, and thermoplastic composites. In some embodiments, the frame 170 may be formed of a coated metal to prevent both corrosion and electrical conduction. According to various embodiments, the frame 170 is generally non-conductive, thereby reducing the likelihood of shorting between electrochemical cells. The base 180 may be formed of one or more materials that provide electrical conductivity and corrosion resistance during operation of the battery. For example, the base 180 may be configured to be electrically conductive in areas where active battery components (e.g., flow structures, MEAs, etc.) lie.

The material for the components (e.g., polymer seal 175, first seal 230, second seal 240, third seal 250, frame 170, and base 180) The factors and characteristics to be considered when selecting the geometric shape may include at least the design of the force concentrator pattern 300, compression load requirements, material compatibility, sealing pressure requirements, material costs, manufacturing costs and ease of manufacture. The diversity of materials made appropriately by the force concentrator pattern 300 described herein allows for selection of less expensive materials and manufacturing processes. For example, inexpensive raw material plastics, some of which are listed herein, may be used in conjunction with a polymeric seal (e.g., a polymeric seal 175, a first seal 230, a second seal 240, and a third seal 250 )). In addition, multicomponent bipolar plates can be expensive to manufacture due to the complex details of the plates that require the use of expensive, conventional milling. The use of the polymer seal 175 and force concentrator pattern 300 as described herein may reduce the cost and complexity of manufacturing the bipolar plates 150 and 160. For example, a frame 170 and a base 180 may be fabricated with a force concentrator pattern 300, whereby the polymer seal 175 and the polymer seal 175, The thickness of the bipolar plates 150 and 160, the manufacturing cost, and the manufacturing complexity can be reduced.

It will be appreciated that the features described herein may also be used in batteries that may be used to seal other components of an electrochemical cell and / or that do not employ a cascade sealing arrangement.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention. It is intended that the specification and examples be considered as exemplary only, with a true scope and concept of the invention being indicated by the following claims.

Claims (20)

A bipolar plate assembly comprising a frame and a base,
Wherein at least one of the frame and the base has a shape of a force concentrator pattern or has a first surface including a force concentrator pattern, the force concentrator pattern partially extending Lt; / RTI >
Wherein the surface area of the force concentrator pattern over the length of the frame or base is substantially constant to produce a uniform compressive force along the length of the frame and / or the base when the bipolar plate assembly is under compression. Plate assembly. The bipolar plate assembly of claim 1, wherein a surface area of the force concentrator pattern across the length of the frame or 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 sealing assembly between the frame and the base. 4. The bipolar plate assembly of claim 3, wherein the sealing assembly is an elastomeric seal or a polymer seal. 4. The bipolar plate assembly of claim 3, wherein the compressive forces on the sealing assembly are distributed substantially evenly throughout the sealing assembly when the bipolar plate assembly is under compression. 2. The bipolar plate assembly of claim 1, wherein the frame and the base are two portions joined together or one integral portion. 7. The bipolar plate assembly of claim 6, wherein at least one of the frame and the base is laminated with a polymeric material or coated with a polymeric film on an upper surface and / or a lower surface. 8. The bipolar plate assembly of claim 7, wherein compressive forces on the polymeric material or polymeric membrane are distributed substantially evenly across the frame and / or base when the bipolar plate assembly is under compression. The bipolar plate assembly of claim 2, wherein the bipolar plate assembly is at least one of a plurality of bipolar plate assemblies forming an electrochemical stack. 3. The bipolar plate assembly of claim 2, wherein the compressive force ranges from 5,000 psig to 40,000 psig. 3. The bipolar plate assembly of claim 2, wherein the thickness of the force concentrator pattern ranges from 0.025 mm to a frame and / or base thickness range. 3. The bipolar plate assembly of claim 2, wherein at least one of the frame and the base has a second surface comprising the force concentrator pattern. A method of assembling a bipolar plate assembly,
Compressing a frame and a base of the bipolar plate assembly, wherein at least one of the frame and the base has a shape of a force concentrator pattern or has a first surface including a force concentrator pattern, And a raised surface partially extending over the first surface,
Wherein the surface area of the force concentrator pattern over the length of the frame or base is substantially constant to produce a uniform compressive force along the length of the frame and / or the base when the bipolar plate assembly is under compression. A method of assembling a plate assembly. 14. The method of claim 13, wherein the frame or to the surface area of the force concentrator pattern across the length of the base of about ² cm 2 / cm to about 10 cm ² / cm range. 14. The method of claim 13 wherein the bipolar plate assembly comprises one or more sealing assemblies between the frame and the base. 16. The method of claim 15, wherein the sealing assembly is an elastomeric seal or a polymer seal. 16. The method of claim 15 wherein compressive forces on the sealing assembly are distributed substantially evenly throughout the sealing assembly when the bipolar plate assembly is under compression. 16. The method of claim 15, wherein the compressive force on the sealing assembly is greater than the yield strength of the material of the sealing assembly. 14. The method of claim 13, wherein the frame and the base are two parts joined together, or one integrated part;
Wherein at least one of the frame and the base is laminated with a polymeric material or coated with a polymeric film on an upper surface and / or a lower surface;
Wherein compressive forces on the polymeric material or polymeric membrane are distributed substantially evenly throughout the frame and / or base when the bipolar plate assembly is under compression. An electrochemical cell comprising a pair of bipolar plate assemblies and a membrane electrode assembly positioned between the pair of bipolar plate assemblies,
Wherein at least one of the bipolar plate assemblies comprises a frame and a base;
Wherein at least one of the frame and the base has a shape of a force concentrator pattern or has a first surface including a force concentrator pattern, the force concentrator pattern includes a raised surface that extends partially over the first surface ;
Wherein the surface area of the force concentrator pattern across the length of the frame or base is substantially constant to produce a uniform compressive force along the length of the frame and / or base when the bipolar plate assembly is under compression. Chemical battery.

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