Sealing method of acid-doped film

Abstract

A method of joining two or more acid-doped polybenzimidazole films includes attaching pairs of first and second substrates to opposing surfaces of respective first and second acid-doped polybenzimidazole films to form first and second film / substrate assemblies. A portion of each of the first and second acid-doped polybenzimidazole films is not covered by each of the first and second substrates. The method further includes immersing at least uncovered portions of the first and second films in a solvent to remove acid therefrom, spraying a fluororubber coating on at least one region of each uncovered portion of the first and second films, placing a second film / substrate assembly over the first film / substrate assembly, and removing the fluororubber coating from the first film / substrate assembly. And bringing the sprayed regions of the first and second films into contact with each other, and applying at least one of pressure or heat to the contacted regions of the first and second films.

Description

Background Technology

[0001] The conversion of thermal or chemical energy into electrical energy, or vice versa, can be achieved in a variety of ways. For example, known electrochemical cells or batteries rely on chemical reactions in which ions and electrons from oxidized reactants are transferred to reduced reactants via different pathways. Specifically, electrons undergo electrical transfer and do work through circuits with an external load, while ions are conducted through an electrolyte separator.

[0002] However, battery-type electrochemical cells can only produce limited energy because the limitations of the battery casing restrict the amount of usable reactants that can be contained within. Although such electrochemical cells can be designed to be charged by applying a reverse polarity current / voltage between the electrodes, this charging requires a separate power source. Furthermore, the electrochemical cell is typically unusable during the charging process.

[0003] The development of fuel cells aims to address the problems associated with battery-type electrochemical cells. In conventional fuel cells, chemical reactants are continuously supplied to and removed from the electrochemical cell. Similar to batteries, fuel cells operate by conducting ionized matter through a selective electrolyte within a membrane electrode assembly (MEA), which typically prevents the passage of electrons and non-ionized matter.

[0004] The most common type of fuel cell is the hydrogen-oxygen fuel cell, which allows hydrogen to pass through one electrode and oxygen through the other. Porous electrodes on both sides of the electrolyte membrane couple electrons from the chemical reaction to an external load via an external circuit. Under the chemical reaction potential of hydrogen and oxygen, hydrogen ions are conducted through the electrolyte membrane to the oxygen side of the cell. On the oxygen side, electrons recombine with hydrogen ions to form hydrogen, which then reacts with oxygen to produce water, which is then discharged from the system. A continuous current is generated as hydrogen and oxygen are continuously supplied to the cell.

[0005] Mechanical heat engines have also been designed and used to generate electricity. These mechanical heat engines operate based on thermodynamic cycles, where shaft work is accomplished by compressing a working fluid using a piston or turbine. The compression process occurs at a low temperature, after which the working fluid's temperature rises. At this high temperature, the working fluid expands against a load (such as a piston or turbine), thus generating shaft work. The key to operating all fluid-driven engines is that the work required to compress the working fluid at low temperatures is less than the work produced by its expansion at high temperatures. This principle applies to all thermodynamic engines that use working fluids.

[0006] For example, a steam engine operates based on the Rankine thermodynamic cycle, in which water is pumped to a high pressure, then heated into steam and expanded by a piston or turbine to do work. An internal combustion engine operates based on the Otto cycle, in which cold ambient air is compressed by a piston and then heated to very high temperatures by combustion of fuel in the cylinder. As the cycle continues, the work done by the heated air resisting piston expansion is greater than the work consumed during the cold compression process.

[0007] The Stirling engine, developed based on the Stirling cycle, aims to provide a highly efficient engine with greater flexibility in heat source selection. The ideal Stirling thermodynamic cycle is comparable in efficiency to the ideal Carnot cycle, which defines the theoretical maximum efficiency of an engine operating by absorbing heat at high temperatures and dissipating heat at low temperatures. However, like all mechanical engines, the Stirling engine suffers from reliability issues and efficiency losses associated with its moving mechanical parts.

[0008] To avoid the inherent problems of mechanical heat engines, the Alkali Metal Thermoelectrochemical Conversion (AMTEC) battery is designed as a thermoelectrochemical heat engine. The AMTEC heat engine utilizes pressure to generate voltage and current by forcing an ionizable working fluid (such as sodium) through an electrochemical cell (membrane electrode assembly, MEA) at high temperatures. The electrodes couple the current to an external load. The pressure difference around the electrolyte membrane forces molten sodium atoms through the electrolyte, generating electrical work. The sodium atoms are ionized upon entering the electrolyte, releasing electrons to the external circuitry. On the other side of the electrolyte, sodium ions recombine with electrons to reform sodium upon leaving the electrolyte, a process similar to that in electrochemical cells such as batteries and fuel cells. The reformed sodium, under low pressure and high temperature, leaves the electrochemical cell as an expanding gas. This gas is then cooled and condenses back into a liquid state. The resulting cryogenic liquid is then repressurized. The operation of the AMTEC engine approximates the Rankine thermodynamic cycle.

[0009] Numerous publications exist on AMTEC technology. See, for example, Conceptual design of AMTEC demonstrative system for 100t / d garbage disposal power generating facility, Qiuya Ni et al. (Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China). Another representative document is the Proceedings of the Intersociety Energy Conversion Engineering Conference and Exhibit (IECEC), Las Vegas, Nevada (July 24-28, 2000), Volume 2 (A00-37701 10-44). See also the American Institute of Aeronautics and Astronautics, Vol. 190, pp. 1295-1299. Report number: AIAA Paper 2000-3032.

[0010] The highly corrosive nature of the alkali metal working fluid leads to reliability issues in AMTEC heat engines. The practicality of AMTEC engines is also very limited. Specifically, because the ion-conducting solid electrolyte only reaches its practical conductivity at high temperatures, AMTEC engines can only operate at very high temperatures. In fact, even the cryogenic pressurization process must be carried out at relatively high temperatures because the alkali metal working fluid, due to its flow throughout the cycle, must always be kept above its melting point. Mechanical pumps and even magnetohydrodynamic pumps have been used to pressurize the cryogenic working fluid.

[0011] To overcome the shortcomings of conventional mechanical and thermoelectrochemical heat engines, a Johnson Thermo-Electrochemical Converter (JTEC) system with an approximate Carnot equivalent cycle was invented (see U.S. Patent No. 7,160,639, filed April 28, 2003, the entire contents of which are incorporated herein by reference). A typical JTEC system is a heat engine comprising a first electrochemical cell (MEA) operating at a certain temperature, a second electrochemical cell (MEA) operating at a different temperature from the first MEA, a conduit system containing a heat exchanger coupling the two cells together, and a supply of an ionizable gas (such as hydrogen or oxygen) as the working fluid contained within the conduit system. Each MEA stack includes a non-porous membrane capable of conducting ions of the working fluid, with porous electrodes located on the opposite side of the membrane.

[0012] In JTEC, the working fluid passes through each MEA stack by releasing electrons to the inlet-side electrode, enabling ions (protons) to conduct across the membrane to the opposite electrode. The working fluid recombines on the opposite electrode because it re-supplyes the electrons that have already passed through an external load or controller as the working fluid ions leave the membrane. If a hydrogen pressure differential is applied around an MEA connected to an electrical load, it will power the load as the hydrogen pressure decreases from high to low. The process can also be reversed. Hydrogen can be pumped from low to high pressure by applying voltage and current to the MEA.

[0013] The high-temperature battery operating under a pressure difference will generate a higher voltage than the low-temperature battery, consistent with the Nernst equation. Just as in other engines, the working fluid (hydrogen in this case) is compressed at low temperatures and expands at high temperatures to produce net power output. A constant pressure difference is maintained by a constant current through both MEAs. Since the current (I) through both batteries is the same, the voltage difference means that the power generated by the expansion of hydrogen in the high-temperature battery is higher than that in the low-temperature battery.

[0014] Developing JTEC for a wide range of applications presented numerous challenges, particularly those related to the use of hydrogen as the working fluid. For example, due to the small size of hydrogen molecules, even minor defects in the conduit system can lead to hydrogen leakage. Specifically, hydrogen leakage can occur at the connection points between the conduit joints between high-temperature and low-temperature cells. Such leakage is undesirable as it reduces the pressure differential of the working fluid around the membrane, thereby decreasing electrical output and overall system efficiency.

[0015] Furthermore, unlike conventional fuel cells where the open-circuit voltage can exceed 1 volt, the Nernst voltage generated by the hydrogen pressure differential around the membrane electrode assembly (MEA) stack is only in the range of approximately 0.2 volts. Therefore, multiple cells must be connected in series to achieve a usable output voltage level. Additionally, each JTEC cell requires a large membrane / electrode surface area to achieve a usable output current level and minimize voltage loss due to membrane resistance. In other words, considering the low operating voltage of a single cell and the low conductivity of available membrane materials, a large membrane surface area is needed to generate a usable power level. Directly connected membrane structures can mitigate the aforementioned hydrogen leakage-related problems by eliminating easily leaking conduit joints.

[0016] Therefore, similar to the membranes used in thermoelectric engines, the membrane needs to possess sufficiently high ionic conductivity to maximize the output voltage, while also requiring high diffusion barrier properties to minimize pressure-induced diffusion of the working fluid (such as hydrogen or any gas with a conductor, such as oxygen) around the membrane, and the resulting reduction in electrical output and efficiency. However, existing hydrogen ion-conducting membrane materials with good ionic conductivity, such as DuPont's polymer Nafion, typically have extremely poor molecular diffusion barrier properties, leading to the required pressure drop losses for operation. Conversely, existing membrane materials with high molecular diffusion barrier properties, such as ceramic ion conductors, typically have relatively low ionic conductivity, especially at low to intermediate temperatures, resulting in high system impedance and large polarization losses. Therefore, a practical method is needed to use existing high-barrier, high-ionic- or high-proton-conductivity materials as thin, large-surface-area membranes to provide a thermoelectric chemical engine that approximates a Carnot equivalent cycle and eliminates the reliability and efficiency problems associated with conventional mechanical engines.

[0017] Therefore, there is a growing interest in the application of solid polymer electrolytes. Compared to traditional alternative membrane materials (such as...) Unlike other electrolytes (whose conductivity depends on water availability and therefore requires external humidification for optimal operation), solid polymer electrolytes (SPEs) do not depend on water availability for proton conductivity, allowing them to operate at high temperatures without external humidification. Therefore, a promising membrane material for SPEs is based on polybenzimidazole (PBI) polymers. PBI polymers are known for their excellent thermal and chemical stability. More specifically, PBI polymers possess inherent high thermal and chemical stability due to their aromatic structure and the strength of the bonds within that structure.

[0018] Several methods have been developed for preparing polybenzimidazole (PBI) solutions that can be cast into thin films. Specifically, PBI films can be used as solid polymer electrolytes by casting films from solution and then doping the films with phosphoric acid (PA) to make the polymer proton-conductive. See, for example, J.S. Wainright et al., “Acid-Doped Polybenzimidazole: A Novel Polymer Electrolyte,” Journal of the Flectroochemical Society, 142(7) (1995).

[0019] Xiao et al. developed a sol-gel process called the "PPA process" (polyphosphoric acid process), which can synthesize PA-doped PBI membranes (see, for example, L. Xiao et al., "Preparation of high-temperature polybenzimidazole fuel cell membranes by sol-gel process", Chemistry of Materials, 17(21), 5328-333(2005)). The acid-doped gel membranes synthesized by the polyphosphoric acid (PPA) process have a high acid content per polymer repeating unit, which gives them high proton conductivity and keeps the mechanical properties of the membrane at a level that allows the polymer to be used in fuel cells. Therefore, acid-doped PBI membranes are particularly suitable for fuel cell applications. However, a limitation of acid-doped PBI-based membranes is that they are not easily bonded to themselves or other materials. Therefore, it becomes difficult to bond PBI membranes together to form sub-assemblies for manufacturing electrochemical battery stacks. Therefore, it is necessary to provide a method for efficiently bonding acid-doped polybenzimidazole (PBI) membranes together.

[0020] Brief Overview

[0021] In summary, one embodiment includes a method of joining two or more acid-doped polybenzimidazole films together. The method includes attaching a pair of first substrates to opposing surfaces of a first acid-doped polybenzimidazole film to form a first film / substrate assembly. A portion of the first acid-doped polybenzimidazole film is not covered by the first substrate. The method further includes attaching a pair of second substrates to opposing surfaces of a second acid-doped polybenzimidazole film to form a second film / substrate assembly. A portion of the second acid-doped polybenzimidazole film is not covered by the second substrate. The method further includes immersing at least uncovered portions of the first and second acid-doped polybenzimidazole films in a solvent to remove acid from at least uncovered portions of the first and second acid-doped polybenzimidazole films; spraying a fluororubber coating onto at least one area of ​​each uncovered portion of the first and second acid-doped polybenzimidazole films; placing the second film / substrate assembly over the first film / substrate assembly and bringing the coated areas of the uncovered portions of the first and second acid-doped polybenzimidazole films into contact with each other; and applying at least one of pressure or heat to the contact areas of the uncovered portions of the first and second acid-doped polybenzimidazole films.

[0022] In one respect, the solvent is deionized water. In another respect, the deionized water is at room temperature, and the immersion step lasts for at least about forty seconds.

[0023] On the other hand, the step of applying at least one of pressure or heat includes applying pressure to the contact area for about 24-48 hours.

[0024] In another aspect, the step of applying at least one of pressure or heat includes applying heat pressure at a temperature of about 60°C for about three minutes.

[0025] In another aspect, the method further includes heating the first and second film / substrate assemblies at a temperature of about 180°C for about forty-five minutes after the attachment step but before the immersion step.

[0026] In another aspect, the method further includes drying the first and second film / substrate assemblies in a drying oven after the spraying step.

[0027] In another aspect, the method further includes, after the immersion step, placing the first and second film / substrate assemblies on a vacuum plate and respectively imprinting the first and second meshes onto the uncovered portions of the first and second acid-doped polybenzimidazole films.

[0028] Another embodiment includes a method for preparing a first film / substrate assembly for bonding with another film / substrate assembly. The method includes attaching a pair of substrates to opposing surfaces of a first acid-doped polybenzimidazole film to form the first film / substrate assembly. A portion of the first acid-doped polybenzimidazole film is not covered by the first substrate. The method further includes immersing at least the uncovered portion of the first acid-doped polybenzimidazole film in a solvent to remove acid from the uncovered portion of the first acid-doped polybenzimidazole film, and spraying a fluororubber coating onto at least one area of ​​the uncovered portion of the first acid-doped polybenzimidazole film.

[0029] On one hand, the solvent is deionized water. On the other hand, the deionized water is at room temperature, and the immersion step lasts for at least about forty seconds.

[0030] In another aspect, the method further includes heating the first film / substrate assembly at a temperature of about 180°C for about forty-five minutes after the attachment step but before the immersion step.

[0031] In another aspect, the method further includes placing the first film / substrate assembly in a drying oven after the spraying step.

[0032] In another aspect, the method further includes placing the first film / substrate assembly on a vacuum plate after the immersion step and imprinting a first grid onto the uncovered portion of the first acid-doped polybenzimidazole film.

[0033] Brief description of each view in the attached figures

[0034] The following detailed description of preferred embodiments will be better understood when read in conjunction with the accompanying drawings. For ease of explanation, the currently preferred embodiments are shown in the drawings. However, it should be understood that the invention is not limited to the precise arrangements and means shown.

[0035] In the attached diagram:

[0036] Figure 1 This is an example method flowchart corresponding to the first embodiment of the present invention; and

[0037] Figure 2A-2C yes Figure 1 A schematic diagram of some of the components and materials used in each step of the provided method.

[0038] Detailed description

[0039] Certain terms used in the following description are for convenience only and are not restrictive. Terms such as “right,” “left,” “lower,” and “upper” are used to indicate directions in the drawings for reference. “Inward” and “outward” refer to directions toward and away from the geometric center of the device and its designated portion, respectively. Terms include those listed above, their derivatives, and terms with similar meanings. Furthermore, “a” and “an” as used in the relevant parts of the claims and description mean “at least one.”

[0040] It should also be understood that the terms “approximately,” “about,” “general,” “substantially,” and similar terms used in this document when describing the dimensions or features of components indicate that the dimensions / features described are not strict limits or parameters and do not exclude minor variations that are functionally similar. At a minimum, such references containing numerical parameters should include variations that do not change the least significant bit when using mathematically and industrially accepted principles (e.g., rounding, measurement or other systematic errors, manufacturing tolerances, etc.).

[0041] It should also be understood that terms such as "first" and "second" are provided for clarity purposes only. The elements or components identified by these terms and their operations can be easily switched.

[0042] Some embodiments of the present invention relate to a method for joining two or more acid-doped PBI films or membranes together. More specifically, it relates to a method for joining two or more acid-doped polymer films or membranes together, said acid-doped polymer films or membranes being prepared by a sol-gel process, preferably using PPA, more preferably synthesized by a PPA process. Even more specifically, it relates to a method for joining two or more PA-doped polymer films or membranes synthesized by a PPA process. While the following discussion relates to scenarios of joining two such films or membranes together, it should be understood that the method can be repeated or replicated as needed to join more films or membranes together. Furthermore, although the following primarily refers to polymer membranes, it should be understood that the method is entirely applicable to any polymer film.

[0043] In the PPA process, when preparing highly acid-doped PBI films, PPA serves as both a polycondensation agent and a casting solvent. Due to its acid content, acid-doped PBI films are highly hygroscopic. Therefore, when an acid-doped PBI film is exposed to air, a layer of water forms on the exposed surface, making it extremely difficult to bond the PBI film to any object (including another PBI film).

[0044] Reference Figure 1 and Figure 2A-2C First and second acid-doped PBI films or films 10, 12 can be formed. In one embodiment, the polymer of films 10, 12 is poly-2,2”-(m-phenylene)-5,5”-dibenzimidazole (m-PBI) or poly[2,2'-(p-phenylene)-5,5'-dibenzimidazole] (p-PBI). Preferably, each film or film 10, 12 can be an acid-doped p-PBI film or film. In one embodiment, the first and second acid-doped PBI films or films 10, 12 are formed by a PPA process.

[0045] In some embodiments, in step 102, the first PBI film 10 may be attached to a pair of first substrates 14a, 14b to form a first film / substrate assembly. For the fabrication of the MEA, the substrates 14a, 14b may be carbon-based electrodes, but other types of substrates, including multilayer substrates, may also be used. To attach the first PBI film 10 to the carbon-based electrode substrate, the substrates 14a, 14b may be hot-pressed onto the first PBI film 10 at a temperature of approximately 160°C with a compression rate not exceeding approximately 30%.

[0046] Adhesion may result in a portion 11 of the first PBI film 10 not being covered by the first substrates 14a, 14b. For example, the surface area of ​​each of the first substrates 14a, 14b may be smaller than the surface area of ​​the first PBI film 10, such that when the first substrates 14a, 14b are attached together (e.g., center-aligned), the edge of the first PBI film 10 may extend beyond the edges of the first substrates 14a, 14b. For example, the uncovered portion 11 of the first PBI film 10 may extend beyond the edges of the first substrates 14a, 14b by about one inch, although the exact amount may vary depending on various factors, including the thickness of the layers. However, in some embodiments, the uncovered portion 11 of the first PBI film may extend beyond the first substrates 14a, 14b in all directions, although the uncovered portion 11 may be shaped and configured as needed to allow for attachment. For example, if desired, for rectangular substrates 14a, 14b, the uncovered portion 11 may only exist on two opposite sides of the rectangle, rather than all four sides.

[0047] In step 104, once the first film / substrate assembly is formed, it can be heated, for example, by placing it in an oven at approximately 180°C for approximately 45 minutes, although other temperatures and durations may also be used. This process causes the first film / substrate assembly to pre-shrink.

[0048] In step 106, at least the uncovered portion 11 of the first PBI film 10 may be immersed in a solvent to remove acid (e.g., PA) from the uncovered portion 11 by leaching or other means. This can be achieved by immersing the entire first film / substrate assembly in the solvent, or by immersing only an amount sufficient to immerse the uncovered portion 11 in the solvent. Alternatively, the individual edges of the uncovered portion 11 of the first PBI film 10 may be immersed in the solvent sequentially to avoid excessive contact between the first substrates 14a, 14b and the solvent. The solvent may be deionized water at room temperature, although other solvents and / or temperatures may be used depending on the properties of the PBI film and the type of acid that needs to be removed from the edges. The purpose of the solvent is generally not to completely remove the acid, nor to densify or otherwise harden the uncovered portion 11 of the first PBI film 10. Therefore, when immersing the edges of the first film / substrate assembly in deionized water, the immersion time for each edge should be at least approximately 40 seconds or several minutes, which differs from other processes that completely remove acid by immersing the PBI film in water for several hours.

[0049] In step 108, the first film / substrate assembly may be placed on a vacuum plate (not shown) with a grid attached (e.g., welded or similarly fixed). In step 110, the grid is imprinted onto the uncovered portion 11 of the first PBI film 10, and the first film / substrate assembly may be placed on the vacuum plate for at least approximately seven minutes. The grid is used to etch or otherwise roughen the surface of the uncovered portion 11 to facilitate the bonding process. Other etching / roughening processes may be used in addition to the grid, or as alternatives. The vacuum plate can be used to ensure that the PBI film remains flat during processing, so other similar control methods may be employed if necessary.

[0050] In step 112, at least one area of ​​the uncovered portion 11 of the first PBI film 10 may be coated with fluororubber. Figure 2B An example is shown where a coating 20 covers an uncovered portion 11 of a first PBI film 10. Although the coating is only applied to the first PBI film 10, coating 20 may also be applied to portions of the first substrates 14a, 14b. Fluororubber can be commercially available from Chemours. Spraying is acceptable, but other types of similar fluororubber sprays may also be used. When applying the coating, it is preferable to place the first PBI film 10 and the substrate assembly in a fume hood. Although Figure 2BThe image shows that the uncovered portion 11 of the first PBI film 10 is entirely covered by the coating 20, but the coating 20 can also be selectively applied to individual areas of the uncovered portion 11. For example, the coating may be applied only to the upward (or downward) facing surface of the uncovered portion 11 of the first PBI film 10. Depending on the configuration, material, and / or bonding strategy, the coating 20 may be applied along the uncovered portion at selected intervals, or other coating patterns may be used.

[0051] In step 114, after the spray coating 20 is applied, the first film / substrate assembly can be dried, for example, in a drying oven at about 100°C for at least about ten minutes, although other times and / or temperatures may also be used.

[0052] Steps 102-114 constitute an example method for preparing a first thin-film / substrate assembly for connection with another component. Figure 1 Steps 116-128 shown are similar to steps 102-114 and can be applied to second or subsequent thin-film / substrate assemblies, for example, as Figure 2A-2B The assembly shown has a second PBI film 12 sandwiched between second substrates 16a and 16b, and provides an uncovered portion 13 that is immersed and coated. Steps 116-128 can be performed simultaneously with steps 102-114, after steps 102-114, alternately with steps 102-114, or in combination thereof. Additional film / substrate assemblies can also be created and processed in a similar manner.

[0053] In step 130, the first and second substrate assemblies can be connected together. Specifically, as shown in the figure... Figure 2C As shown, the second film / substrate assembly can be placed on top of the first film / substrate assembly. At least the coated portions of the uncovered portions 11, 13 of the first and second PBI films 10, 12 can contact each other, for example, by bending or otherwise manipulating the uncovered portions 11, 13 of the first and second PBI films 10, 12. It should be noted that in some embodiments, when the two uncovered portions 11, 13 are in contact, the coating 20 only needs to be present on one of the PBI films 10, 12, for example, when the coating is applied only to one of the PBI films 10, 12, or when the coating 20 is patterned (e.g., an area with the coating 20 on the uncovered portion 11 of the first PBI film 10 contacts an area without the coating 20 on the uncovered portion 13 of the second PBI film 12, and vice versa), etc.

[0054] In step 132, at least one of pressure or heat may be applied to the contact areas of the uncovered portions 11, 13 of the first and second PBI films 10, 12 to form a bond. In one embodiment, this step includes applying pressure to the contact areas for about 24-48 hours, or until the materials are completely bonded together. In another embodiment, this step includes applying hot pressing (not shown) at a temperature of about 60°C for about three minutes, although other times and / or temperatures may be used depending on the materials and conditions. The intermediate fluororubber coating further facilitates the bond between the first and second (and additional) PBI films.

[0055] Although the present invention is described above and in the accompanying drawings for use with a PBI film sandwiched between a pair of substrates, the methods herein, or minor variations thereof, can also be used for PBI films attached to a single substrate or two or more substrates. The methods herein, or minor variations thereof, can also be used for PBI films not attached to any substrate.

[0056] Those skilled in the art will recognize that the boundaries between the above operations are merely illustrative. Multiple operations may be combined into a single operation, a single operation may be decomposed into multiple operations, and operations may be performed with at least partial overlap in time. Furthermore, alternative implementations may include multiple instances of a particular operation, and in many other implementations, the order of operations may also be changed.

[0057] Although specific and different embodiments have been shown in the accompanying drawings, individual elements or combinations of elements in different embodiments may be combined with each other without departing from the spirit and scope of the invention. Therefore, a single feature described herein with respect to only one embodiment should not be construed as contradicting other embodiments described herein or the content otherwise covered by the invention.

[0058] Those skilled in the art will understand that modifications can be made to the embodiments without departing from the broad inventive concept of the implementation. Therefore, it should be understood that the invention is not limited to the specific embodiments disclosed, but is intended to cover all modifications within the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for joining two or more acid-doped polybenzimidazole films together, characterized in that, The method includes: A pair of first substrates are attached to opposite surfaces of a first acid-doped polybenzimidazole film to form a first film / substrate assembly, wherein a portion of the first acid-doped polybenzimidazole film is not covered by the first substrate; and a pair of second substrates are attached to opposite surfaces of a second acid-doped polybenzimidazole film to form a second film / substrate assembly, wherein a portion of the second acid-doped polybenzimidazole film is not covered by the second substrate. At least uncovered portions of the first and second acid-doped polybenzimidazole films are immersed in a solvent to remove acid from at least uncovered portions of the first and second acid-doped polybenzimidazole films; A fluororubber coating is sprayed onto at least one area of ​​each uncovered portion of the first and second acid-doped polybenzimidazole film. The second film / substrate assembly is placed above the first film / substrate assembly, and the sprayed coating areas of the uncovered portions of the first and second acid-doped polybenzimidazole films are brought into contact with each other; and Apply at least one of pressure or heat to the contact area of ​​the uncovered portion of the first and second acid-doped polybenzimidazole films.

2. The method as described in claim 1, characterized in that, The solvent is deionized water.

3. The method as described in claim 2, characterized in that, The deionized water is at room temperature, and the immersion step lasts for at least about forty seconds.

4. The method as described in claim 1, characterized in that, The step of applying at least one of pressure or heat includes applying pressure to the contact area for about 24-48 hours.

5. The method according to claim 1, characterized in that, The step of applying at least one of pressure or heat includes applying heat pressure at a temperature of about 60°C for about three minutes.

6. The method as described in claim 1, characterized in that, The method further includes heating the first and second film / substrate assemblies at a temperature of about 180°C for about forty-five minutes after the attachment step but before the immersion step.

7. The method as described in claim 1, characterized in that, The method further includes drying the first and second film / substrate assemblies in a drying oven after the spraying step.

8. The method as described in claim 1, characterized in that, The method further includes, after the immersion step, placing the first and second film / substrate assemblies on a vacuum plate and imprinting the first and second meshes onto the uncovered portions of the first and second acid-doped polybenzimidazole films, respectively.

9. A method for preparing a first thin film / substrate assembly for bonding with another thin film / substrate assembly, characterized in that, The method includes: A pair of substrates are attached to opposite surfaces of a first acid-doped polybenzimidazole film to form a first film / substrate assembly, wherein a portion of the first acid-doped polybenzimidazole film is not covered by the first substrate; The uncovered portion of the first acid-doped polybenzimidazole film was immersed in a solvent to remove acid from at least the uncovered portion of the first acid-doped polybenzimidazole film; and A fluororubber coating is sprayed onto at least one area of ​​the uncovered portion of the first acid-doped polybenzimidazole film.

10. The method as described in claim 9, characterized in that, The solvent is deionized water.

11. The method as described in claim 10, characterized in that, The deionized water is at room temperature, and the immersion step lasts for at least about forty seconds.

12. The method as described in claim 9, characterized in that, The method further includes heating the first film / substrate assembly at a temperature of about 180°C for about forty-five minutes after the attachment step but before the immersion step.

13. The method as described in claim 9, characterized in that, The method further includes placing the first film / substrate assembly in a drying oven after the spraying step.

14. The method as described in claim 9, characterized in that, The method further includes, after the immersion step, placing the first film / substrate assembly on a vacuum plate and imprinting the first mesh onto the uncovered portion of the first acid-doped polybenzimidazole film.

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