Ion-conducting film, component having an ion-conducting film, and method for forming the same.

Abstract

The present invention provides an ion-conducting film (10), a component (100) having the ion-conducting film (10), and a method for manufacturing the film (10) and the component (100). [Solution] The ion-conducting membrane (10) comprises a homogeneous blend (12) and one or more additives (14). The selected one or more polymers are present in a mass percentage ranging from 1% to 40%. The ion-conducting membrane (10) of the present invention simultaneously increases the output and efficiency of devices by combining advances in materials chemistry, nanotechnology, and manufacturing. The ion-conducting membrane (10) of the present invention overcomes the limitations of current known technologies without impairing advantageous properties. The membrane (10) of the present invention provides a nonlinear performance improvement in electrochemical devices, resulting in cost reductions at the system-wide level.

Description

[Technical Field]

[0001] This disclosure relates to ion-conducting films. More specifically, this disclosure relates to ion-conducting films, components having an ion-conducting film as one of their parts, ion-conducting films, and methods for forming components. [Background technology]

[0002] Ion-conducting membranes are solid materials that allow ions to be transported through them. They are used in devices for applications such as energy generation, energy conversion, and energy storage. Ion-conducting membranes are also electrical insulators. They determine the output (energy extraction rate) and efficiency of energy devices. Ion-conducting membranes are different from separators that allow the transport of entire flammable organic liquids through micropores. The stability of an ion-conducting membrane determines the operating window of the device.

[0003] Ion-conducting membranes can be effectively used for energy generation, conversion, and storage. Fuel cells are energy conversion devices that convert fuel into electricity. Electrolytes function inversely to fuel cells, producing fuel (such as H2) when electricity is supplied. Batteries store energy. At a given energy density, the power density of a battery is fixed, and vice versa. Flow batteries combine features of both batteries and fuel cells into a single device. In flow batteries, as in fuel cells where fuel is stored separately from the stack, energy is stored in a separate tank in a chemical form and then flows to a stack that converts this chemical energy into electrical energy. High-efficiency ion-conducting membranes can enhance the performance of devices and expand their applications.

[0004] The first ion-conducting membranes developed were used in low-temperature polymer electrolyte membrane (LT-PEM) fuel cells, also known as proton exchange membrane (PEM) fuel cells. Nafion®, developed by Dupont in 1970, has become an industry standard due to its excellent chemical stability and ionic conductivity under humid conditions. However, Nafion® can only conduct cations, has poor selectivity among cations, and requires a water management system. It also operates only below 120°C, limiting the types of devices in which it can be used. The use of Nafion® is also limited by its cost. Ion-conducting membranes containing polybenzimidazole (PBI) have been developed for operation under anhydrous conditions. PBI-based ion-conducting membranes conduct protons (H) along the polymer backbone by acid doping. + Ions are conducted through the traps of the PBI. Increasing the ionic conductivity of a PBI-based film comes at the expense of its strength. Crosslinking increases the strength of the film, but often leads to a trade-off with other properties. Crosslinking generally occurs at the expense of the protonated amide bonds of PBI bonding with another polymer, so that site can no longer access proton hopping, resulting only in increased strength. Conductivity, selectivity, and strength are orthogonal properties in current material systems, and an improvement in one property is offset by a decrease in the related property.

[0005] Ion conductors for metallic batteries (lithium-air, lithium-sulfur, aluminum-air, zinc-air, etc.) generally use ceramic electrolytes. The anode and cathode sides present various challenges in the construction of such devices. Often, the presence and growth of dendrites due to the electrolyte, electrode instability, and active material crossover degrade the performance of such batteries. The metallic anode, for example lithium, is bonded or deposited with the ceramic electrolyte through a specific technique. Dendrites grow from the surface of the metallic anode through the electrolyte. Multiple dendrites can grow and spread through the bulk electrolyte. The cathode side uses electrodes with different properties compared to the anode. Furthermore, the interface between the cathode and anode needs to be designed to selectively allow the desired ions. Modern metallic batteries and modern solid-state batteries are subcategories of this type of battery, using solid ion conductors as described above, sometimes Nafion®. These factors impose limitations on the output that can be extracted from these battery systems.

[0006] Flow batteries often utilize polyvalent cathode and anode electrolytes. Therefore, the use of ion-conducting membranes capable of selectively transporting specific types of cations or anions is beneficial in flow batteries. Such membranes should possess two important performance parameters: high ionic conductivity and high ion selectivity for the key ions contributing to the function.

[0007] First-generation separators, also known as nonzero gap separators, are physical separators using a membrane. Such porous separators have the disadvantage of large crossovers, thus limiting the operating window of the device. Second-generation membranes were based on perfluorosulfonic acid (PFSA). PFSA-based membranes sacrifice selectivity due to Donnan's membrane equilibrium. This equilibrium, derived from the second law of thermodynamics, deals only with fully ionized electrolytes crossing the permeable barrier. Examples include Teflon®, which has a hydrophobic backbone and an ionogenic group SO3. - The structure of a PFSA-based membrane with [specific properties] leads to the conditions of Donnan equilibrium. When equilibrium is reached, in a system containing water or a polar solvent, all cations diffuse from one phase (or region) to the other. In the presence of a multi-cation system such as a flow battery, an increase in the charge / discharge rate under dynamic conditions is limited by the maximum current density that can be drawn, as countercations also pass through the membrane. This leads to a permanent degradation of the battery's capacity.

[0008] To mitigate some of the limitations of low-temperature proton exchange membrane fuel cell (LT-PEM) systems, high-temperature proton exchange membranes (HT-PEMs) based on anhydrous proton conduction have been developed. Therefore, there is a need for an ion-conductive membrane that can maintain its conductivity at higher temperatures without sacrificing selectivity or its mechanical resilience. The second-generation membranes were constructed around polybenzimidazole (PBI), with improved proton conductivity achieved by impregnating PBI with phosphoric acid. The drawback of such phosphoric acid-based PBIs is that a high level of acid content is required for high conductivity, and this results in the degradation of mechanical properties. Some of the techniques used in the prior art include crosslinking, post-treatment, functionalization of PBI, and the use of additives such as graphene oxide (GO). However, GO is reduced above 160 °C to reduced graphene oxide (r-GO), and it is electronically conductive. This leads to a loss of conductivity, so the amount of graphene oxide added to the system is limited. If a percolation network is present, it can short-circuit the system. The stacking of multilayer graphene hinders proton transport in the thickness direction.

[0009] In the case of direct methanol fuel cells (DMFCs), the second-generation membranes limit the concentration of methanol used as the input fuel due to methanol crossover. DMFCs are limited by using methanol concentrations of 1 molar to 3 molar as the fuel supply. At such low concentrations, a high degree of dilution with water is required. Price, cost-to-performance analysis shows that methanol concentrations above 10 M are required to be competitive with other competing technologies such as diesel generators. Feng, Yan, et. al., "A selective electrocatalyst-based direct methanol fuel cell operated at high concentrations of methanol.", Science Advances vol. 3, pp 1-7 (2017).

[0010] The first-generation and second-generation anion conductors have several common drawbacks, such as a figure-of-merit tradeoff between anion conductivity and mechanical properties. And because anions (OH - ) tend to be larger compared to protons, this incremental tradeoff is maintained at a high level. A common method for introducing anion charge carriers or ionomeric groups involves quaternizing the polymer backbone with quaternary ammonium functional groups. In the case of operation in a strong alkali medium such as potassium hydroxide or sodium hydroxide, the interaction between the strong base and the anionic ionogenic groups bonded to the polymer chain leads to chemically induced mechanical degradation. This mechanism is known as Hofmann degradation. A common prior art goal is to obtain a conductive membrane that is mechanically strong and stably maintains anion conductivity over a wide range of temperatures.

[0011] Currently known membranes have technical limitations regarding the ways in which individual devices can be operated, and currently, there are no membranes that can solve these limitations while being compatible across various types of devices as intended. The orthogonal property requirements of selectivity, conductivity, and strength impose limitations on the operating conditions of the devices. Primarily, these types of membranes are polymer chemistry-driven by specific applications and limited operating conditions. The membranes, compositions, and methods of manufacturing disclosed in the present invention provide improved strength, selectivity, and conductivity over known membranes in various applications, including high temperatures and other difficult operating conditions.

Summary of the Invention

Problems to be Solved by the Invention

[0012] This summary is provided to briefly present a series of ideas that are further described in the detailed description of this disclosure. This summary is not intended to identify important or essential ideas of the present invention of the subject matter, nor is it intended to define the scope of this disclosure.

Means for Solving the Problems

[0013] This disclosure relates to an ion-conducting membrane comprising a homogeneous blend of polybenzimidazole (PBI) and one or more polymers selected from the group consisting of polyvinylidene difluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) PVDF-HFP, chitosan, and functionalized chitosan. One or more additives are selected from the group consisting of graphene oxide (GO), functionalized graphene oxide (functionalized GO), and hexagonal boron nitride (h-BN). The selected one or more polymers are present in a mass percentage in the range of 1% to 40%, while the mass percentage of the selected additives is in the range of 0.5% to 80%. The additives are dispersed in the homogeneous blend with a dispersion amount of more than 80% and an aggregate amount of less than 30%. The ion-conducting membrane has a conductivity of 1 S / cm at 30°C. 2 It may have an ultra-high ion conductance per unit area.

[0014] Furthermore, this specification also teaches a component comprising an ion-conducting membrane comprising a homogeneous blend of PBI and one or more polymers selected from the group consisting of PVDF, PVDF-HFP, chitosan, and functionalized chitosan, wherein the mass percentage of one or more polymers is in the range of 1% to 40%. The ion-conducting membrane of the component has one or more additives selected from the group consisting of graphene oxide, functionalized graphene oxide, and h-BN, wherein the mass percentage of one or more additives is in the range of 0.5% to 80%. The additives are dispersed in the homogeneous blend with a dispersion amount of more than 80% and an aggregate amount of less than 30%, and the ion conductance per area of ​​the membrane is 1 S / cm at 30°C. 2 It's incredible.

[0015] A method for producing an ion-conducting film according to the teachings of the present invention comprises dissolving a PBI polymer and one or more polymers selected from the group consisting of PVDF, PVDF-HFP, chitosan, and functionalized chitosan in one or more solvents selected from the group consisting of N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), phosphoric acid, polyphosphate, formic acid, KOH, and ethanol. This step forms a homogeneous polymer solution in which the mass percentage of the selected one or more polymers is in the range of 1% to 40%. One or more additives selected from the group consisting of graphene oxide, functionalized graphene oxide, and hexagonal boron nitride (h-BN) are dispersed in one or more solvents selected from the group consisting of DMAc, DMF, DMSO, NMP, THF, phosphoric acid, polyphosphate, formic acid, KOH, and ethanol to form an additive dispersion in which the mass percentage of one or more additives is in the range of 0.5% to 80%. Next, the polymer solution and the additive dispersion are homogeneously mixed to obtain a pre-forming solution. A sheet is formed from the pre-forming solution, the solvent is removed, and the ion conductance per area is 1 S / cm² at 30°C. 2 An ion-conducting film with high conductivity is obtained, and the additive is dispersed with a dispersion amount of more than 80% and an aggregate amount of less than 30%.

[0016] To further illustrate the merits and features of this disclosure, a more detailed description of this disclosure is provided with reference to specific embodiments shown in the accompanying drawings. It should be understood that these drawings only illustrate typical embodiments of this disclosure and should therefore not be considered limitations on the scope of this disclosure. This disclosure is described and explained with further specificity and detail using the accompanying drawings.

[0017] These and other features, aspects, and advantages of the exemplary embodiments can be better understood by referring to the attached drawings and reading the following detailed description, where similar reference numerals throughout the drawings represent similar parts. [Brief explanation of the drawing]

[0018] [Figure 1] Figure 1 shows a film (10) containing additives (14) of different dimensions (ranging from nano to mesoscale), different shapes, and size distributions according to one embodiment of the present disclosure. [Figure 2A] Figure 2A shows a film (10) having a linearly sloped additive (14) dispersion according to one embodiment of the present disclosure. [Figure 2B] Figure 2B shows a film (10) having a nonlinear gradient additive (14) dispersion according to one embodiment of the present disclosure. [Figure 2C] Figure 2C shows a film (10) having an additive (14) dispersion with a different nonlinear gradient, according to one embodiment of the present disclosure. [Figure 3A] Figure 3A shows a film (10) integrated with two nano / microfiber layers according to one embodiment of the present disclosure. [Figure 3B] Figure 3B shows a film (10) with an embedded nano / microfiber layer according to one embodiment of the present disclosure. [Figure 3C] Figure 3C shows a film (10) having an integrated nano / microfiber layer and coupled to an electrode, according to one embodiment of the present disclosure. [Figure 4A] Figure 4A shows the arrangement of additives (14) of different length scales in a film (10) according to one embodiment of the present disclosure. [Figure 4B] Figure 4B shows a nanofiber porous mat (20) having a nanoadditive (14) according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0019] In the diagram, the characteristic parts are identified by numbers. The characteristic parts are identified as follows: 10 membrane; 12 polymer blend; 14 one or more additives; 20 nanofiber mat; 22 nanofibers; 30 substrate / electrode / electrolyte; and 100 component.

[0020] Furthermore, those skilled in the art will understand that the elements in the figures are simplified and not necessarily drawn to scale. In addition, with respect to the construction of the device, one or more components of the device may be represented in the figures by conventional reference numerals, and the figures may show only certain details relevant to understanding embodiments of the invention, so as not to obscure the figures by details that are readily apparent to those skilled in the art, for whom this specification is beneficial.

[0021] This disclosure provides for an ion-conducting film (10), a component (100) having the ion-conducting film (10), and a method for manufacturing the film (10) and the component (100). The ion-conducting film (10) conducts different types of charged chemical species, including negatively charged particles, which may be cations, more specifically protons (H+) and transition metal ions, and hydroxyl (OH-) ions.

[0022] The ion-conducting membrane (10) may be used in electrochemical devices including flow batteries, fuel cells, electrolysis devices, and advanced metal batteries. The membrane (10) disclosed herein has advantageous properties when used in at least one of the electrochemical devices listed above.

[0023] Figure 1 shows an ion-conducting membrane (10). The disclosed ion-conducting membrane (10) comprises a homogeneous blend (12) of two or more polymers in which one or more additives (14) are dispersed throughout. In this specification, “homogeneous blend” means a solid material in which the raw material components are mixed at the molecular level and the raw material components are indistinguishable from each other by physical appearance on a length scale larger than the molecular dimensions. PBI is one of the polymers of the homogeneous blend (12).

[0024] Polybenzimidazole (PBI) contains a benzimidazole repeating unit. The typical chemical name of a PBI polymer is "poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole]", commonly known as meta-PBI. Other known PBIs are para-PBI, PBI-OO, O-PBI, and AB-PBI. For the purposes of this disclosure, PBI means all of the different types of PBI described above.

[0025] PBI possesses excellent mechanical properties and thermochemical stability. It has a high glass transition temperature of 430°C. g It possesses [specific properties]. Its melting point is also very high, exceeding 600°C. The cost of PBI is approximately two orders of magnitude lower than that of Nafion®.

[0026] Homogeneous blend (12) also includes one or more other polymers in addition to PBI. These one or more other polymers may include poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP), chitosan, functionalized chitosan, or any combination thereof. In this specification, chitosan is a linear polysaccharide composed of randomly distributed β-(1→4)-linked D-glucosamine (deacetylation units) and N-acetyl-D-glucosamine (acetylation units). Furthermore, chitosan and functionalized chitosan as used herein may also be found in Shanta Pokhrel et. al., “Functionalization of chitosan polymer and their applications”, Journal of Macromolecular Science, Part A Pure and Applied Chemistry, vol. 56, pp 450-475 (2019).

[0027] In the homogeneous blend (12), the polymers are present in a specific ratio. The mass percentage of one or more polymers in the homogeneous blend (12) is in the range of 1% to 40%. In some embodiments, the mass percentages of the various polymers may vary to any percentage within the range of 1% to 40%. As used herein, the "mass percentage" of a raw material means the mass of the raw material as a percentage of the mass of the PBI. More specifically, the "mass percentage" of a raw material component is calculated by dividing the mass of the raw material component by the mass of the PBI and multiplying by 100. As used herein, the percentage of a raw material component, m f , is defined as follows.

Number

[0028] In addition to the polymers, the ion conductive membrane (10) also includes one or more additives (14). As used herein, "additive (14)" means any raw material component that is part of the membrane (10), which is mixed with the homogeneous blend (12) and can be distinguished from the physical appearance at a length scale larger than the molecular dimensions. In various embodiments of the membrane (10) formulation of the present disclosure, the mass percentage of one or more additives (14) may vary to any percentage within the range of 0.5% to 80%.

[0029] Examples of the one or more additives (14) include graphene oxide (GO), functionalized graphene oxide (functionalized GO), hexagonal boron nitride (h-BN), or any combination thereof. The functional groups of GO include OH - groups, NH - 2 groups, COOH -One or more of the groups may be mentioned. The mass percentage of the additive (14) is in the range of 0.5% to 80%. In some embodiments, the mass of the additive (14) may be greater than the mass of the PBI. In such cases, the main component of the membrane (10) is the additive (14), and the polymer blend (12) acts as a supporting material.

[0030] The advantageous properties of the disclosed membrane (10) are a result of the added additive (14), the proportion of the additive (14), and the membrane (10) formation process, all of which work synergistically to promote the permeation of desirable ions through the membrane (10) and prevent the permeation of undesirable chemical species.

[0031] One objective of this disclosure is to increase the number of active pathways for desired ions by reducing the energy barrier for ion transport and increasing the degree of freedom of movement. The ion-conducting membrane (10) has an internal structure similar to a randomly distributed fractal network of nanoscale additives (14) in a polymer matrix. The nanoscale morphology and ion channel interactions and access created by the specific processing techniques disclosed herein result in a nonlinear increase in the output and energy efficiency of electrochemical devices having the ion-conducting membrane (10).

[0032] Another object of this disclosure is the use of additives (14) to assist in increasing conductance per unit area and reducing the transmittance of undesirable chemical species, such as vanadium ions in the case of vanadium redox flow batteries and methanol molecules in the case of direct methanol fuel cells. Additives (14) act as nanoscale reinforcing agents. Additives (14) can enhance mechanical stability, thermal stability, and electrochemical stability. The interaction energy between the polymer of blend (12) and additives (14), along with the processing parameters, determines the non-aggregated dispersion, and thus results in a high dispersion amount and a low aggregate amount. Some dimensions of additives (14) can be on the nanometer scale. In some embodiments, at least one dimension of additives (14) is in the range of 1 nm to 1000 nm.

[0033] The degree of dispersion, measured by the amount of dispersed material, and the degree of agglomeration, measured by the amount of aggregated material, contribute to the realization of advantageous properties. The amounts of dispersed and aggregated additive (14) present in the membrane (10) are measured as shown in Tyson, BM, et al. “A quantitative method for analyzing the dispersion and agglomeration of nano-particles in composite materials,” Composites: Part B, vol. 42, pp. 1395-1403 (2011).

[0034] For best results, the amount of dispersion of one or more additives (14) should be as high as possible (ideally close to 100%), and the amount of aggregates should be as low as possible (ideally close to 0%). The amount of dispersion in the ion-conducting membrane (10) is greater than 80%, and the amount of aggregates is less than 30%. In some embodiments, the ion-conducting membrane (10) has a dispersion amount of greater than 85% and an aggregate amount of less than 15%.

[0035] Typically, a key performance parameter of a film (10) used in electrochemical devices is its ionic conductivity. The performance of an electrochemical device is expressed in S / cm².2 The current density is determined primarily by the conductance per unit area, measured in units of . The film (10) described herein has a current density of 1 S / cm² when measured at 30°C. 2 It has a conductance per unit area of ​​1 S / cm². Conductance per unit area is the ionic conductivity per unit area of ​​the film (10). In some embodiments, the conductance per unit area of ​​the ion-conducting film (10) is 1 S / cm² under operating conditions. 2 It is extremely high. For example, in the case of a membrane (10) formed for use in an HT-PEM fuel cell, the conductance per unit area is 50 S / cm² in the temperature range of 160°C to 200°C. 2 It could be that height.

[0036] In any electrochemical application, the stability of the membrane (10) during long-term operation is extremely important. The membrane (10) described herein may be stable for a period of at least 2000 hours or 2000 cycles under the corresponding operating conditions.

[0037] Another embodiment of the present disclosure is a method for forming an ion-conductive film (10). The method includes the steps of preparing a pre-forming solution, forming the film (10) on a substrate, and removing the solvent. In some embodiments, if the film (10) is formed on a substrate that is not the substrate used in the end application, the method may further include the step of separating the film (10) from the substrate.

[0038] The pre-forming solution is formed by combining at least two parts. The first part is a homogeneous solution obtained by mixing two or more polymers in a solvent. The second part is an additive (14) dispersion in which the additive (14) is dispersed in a solvent. The solvent used herein may be an organic solvent or a combination of one or more solvents. The one or more solvents may be selected from the group consisting of DMAc, DMF, DMSO, NMP, THF, phosphoric acid, polyphosphate, formic acid, KOH, and ethanol. The solvents used for the first and second parts may be the same or different. In some embodiments, the same solvent is used for both parts. In some embodiments, a combination of two or more solvents may be used.

[0039] PBI is an important part of the homogeneous polymer solution. The polymer constituting the first part together with PBI may be one or more polymers selected from the group consisting of PVDF, PVDF-HFP, chitosan, and functionalized chitosan. The mass percentage of the selected one or more polymers is in the range of 1% to 40%. The mass ratio of polymer to solvent is adjusted so that the desired viscosity is obtained in the final pre-forming solution. The mass fraction of polymer in the final polymer solution is less than 0.2.

[0040] In some embodiments, a small amount of lithium chloride (LiCl) is added to promote the dissolution of the polymer. The mass percentage of LiCl is 10% or less. The LiCl added at this stage is ultimately removed from the film (10) in a solvent removal step.

[0041] The second part or additive (14) dispersion may contain one or more additives (14) selected from the group consisting of GO, functionalized GO, and h-BN. The solvent may be one or more solvents selected from the group consisting of DMAc, DMF, DMSO, NMP, THF, phosphoric acid, polyphosphate, formic acid, KOH, and ethanol. The mass percentage of one or more additives (14) is in the range of 0.5% to 80%. The mass ratio of additive (14) to solvent is adjusted so that the desired viscosity is obtained in the final pre-forming solution.

[0042] A homogeneous polymer solution is prepared by dissolving the selected polymer in a solvent by stirring and heating. The dissolution temperature varies within the range of 30°C to 250°C. The heating process may involve multiple steps of heating at different rates and soaking at multiple set temperatures over different durations.

[0043] In some embodiments, an autoclave equipped with a mechanical stirrer is used to dissolve the polymer in a solution. Various dissolution parameters, such as the polymer-to-solvent mass ratio, the total volume of the polymer-solvent mixture, the stirring speed, and the maximum temperature and pressure of the mixture in the autoclave, are selected to obtain a homogeneous solution. The maximum temperature of the mixture inside the autoclave may be 230°C or less at a pressure of 3 bar or less.

[0044] A dispersion of additive (14) in a solvent is prepared by alternately stirring and mechanically sonicating one or more additives (14) and the solvent. The stirring speed, stirring duration, and sonication duration are selected to obtain the desired dispersion.

[0045] In the next step, the additive (14) dispersion is mixed with the homogeneous polymer solution to form a pre-forming solution. Good mixing is achieved by alternating stirring and sonication of the pre-forming solution. The stirring speed, stirring duration, and sonication duration are selected to obtain a pre-forming solution with the desired viscosity. The viscosity of the pre-forming solution is in the range of 20 cmpoise to 3000 cmpoise.

[0046] The film (10) is formed by casting a preforming solution onto a suitable substrate with a doctor blade. The gap between the edge of the doctor blade and the surface of the substrate to which the film (10) is cast is adjusted to form a film (10) of the desired thickness. The casting speed is adjusted to form a monolithic film (10) without pinholes. Once cast with the doctor blade, the preforming solution forms a sheet. This sheet is then heated in a hood equipped with an electric heater or infrared heater to form a film (10) by uniformly evaporating the solvent. The heating rate, maximum temperature, and duration of soaking of the film (10) at the set temperature are adjusted to form a film (10) free of residual solvent or defects. The maximum heating temperature is in the range of 30°C to 250°C. In some embodiments, the cast film (10) was heated in a hot air oven to evaporate the solvent. A heating-sowing sequence is selected to remove all solvent.

[0047] After heat treatment, the film (10) is separated from the substrate. Separation can be achieved using a variety of liquids, such as water, isopropyl alcohol, methanol, ethanol, diluted inorganic acid, or mixtures thereof.

[0048] In some embodiments, the film (10) is formed by spraying a pre-forming solution onto a suitable substrate. The viscosity of the pre-forming solution is in the range of 20 centipoise to 3000 centipoise. The film (10) is then heated to a temperature in the range of 30°C to 250°C to remove the solvent.

[0049] In some embodiments, the film (10) is also formed by electrospinning a pre-forming solution onto a suitable substrate. The viscosity of the pre-forming solution is in the range of 20 cmpoise to 3000 cmpoise. The formed fibers are then post-treated.

[0050] In some embodiments, the membrane (10) has a dispersion amount of more than 80% and an aggregate amount of less than 20%, and the ion conductance per unit area of ​​the membrane (10) is 1 S / cm² at 30°C. 2 It's incredible.

[0051] The ion-conducting membrane (10) can be adapted for use in multiple manufactured articles, such as various devices and systems. Devices manufactured using such membranes (10) include batteries, metal-air batteries, redox flow batteries, fuel cells, high-temperature proton exchange membrane (HT-PEM) fuel cells, electrolytic devices, different types of electrolytic devices, direct-vapor fuel cells, direct methanol fuel cells (DMFCs), high-temperature direct vapor fuel cells, high-temperature direct methanol fuel cells (HT-DMFCs), metal alkaline-earth batteries, ammonia generators, and lithium-ion extraction reactors.

[0052] In some embodiments, the ion-conducting film (10) can be used in a flow battery. The ion-conducting film (10) used in such applications is intended to have high ionic conductivity for desired ions, more specifically protons, and low transmittance for any undesirable chemical species. For example, in a total vanadium redox flow battery, V 2+ , V 3+ , V 4+ , and V 5+ However, these are chemical species involved in the chemical reaction. The membrane (10) contains protons (H + It is desirable that the film (10) has high conductivity to the vanadium ions, but it is also desirable that the film (10) prevent crossover of the vanadium ions through the film (10) as described above.

[0053] Another important performance parameter of the ion-conducting film (10) in a flow battery is the conductivity per unit area of ​​the film (10), because the current density of the film (10) depends on the conductance per unit area. Conductance per unit area is expressed as S / cm 2It is specified in units of and is a measure per unit area of ​​the membrane (10) of the degree to which protons are made conductable through the membrane (10) itself. For reasonable performance, in an electrochemical device, the conductance per unit area of ​​the membrane (10) should be at least 1 S / cm². 2 It should be the case that conductance per unit area can be increased by decreasing the thickness of the film (10) (the dimensions of the film (10) in the direction parallel to the permeability of ions through the film (10)), and therefore it is a property that depends on the thickness of the film (10). The parameter that does not depend on the dimensions of the film (10) is the "ionic conductivity," which is specified in units of S / cm. While conductance per unit area can be increased by decreasing the thickness of the film (10), mechanical properties such as tensile strength (UTS) may be impaired by decreasing the thickness. Therefore, it is generally not advisable to arbitrarily reduce the thickness of the film (10) in order to increase conductance per unit area.

[0054] If the membrane (10) allows undesirable chemical species, such as vanadium ions in the example of a vanadium redox flow battery, to permeate through the membrane itself, the flow battery loses its energy storage capacity. This is called capacity degradation of the flow battery. Capacity degradation can be prevented by preventing the flow of undesirable ions through the membrane (10). Permeability is a parameter that quantifies the permeation of undesirable chemical species through the membrane (10). The unit of permeability is cm. 2 The value is / min. Selectivity is a parameter that takes into account both ionic conductivity and transmittance. Selectivity is defined as the ratio of ionic conductivity to transmittance, and it is S × min / cm 3 It is specified in units of [unit].

[0055] A typical value for the selectivity of commercially available films (10) commonly used in flow cells is 10 at room temperature, even with a high ionic conductivity of 0.1 S / cm. 5 S×min / cm 3The order of magnitude is such that these films (10) easily allow undesirable chemical species to pass through, and therefore the transmittance becomes very high. Therefore, in the case of a film (10) with an ionic conductivity of 0.1 S / cm used in a typical vanadium redox flow cell, for example V 4+ The transmittance is 10 -6 cm 2 The selectivity is 1 × 10⁻⁶ / min, and as a result, the selectivity is 1 × 10⁻⁶ 5 S×min / cm 3 This means that the selectivity of the membrane (10) can be increased by more effectively blocking the permeation of undesirable chemical species. For example, by reducing the transmittance by a certain order of magnitude, the selectivity of the membrane (10) can be increased by the same order of magnitude.

[0056] During operation in a flow battery, the ion-conducting membrane (10) is typically present with a flowing liquid electrolyte. For example, in a vanadium redox flow battery, the liquid electrolyte may be a vanadium salt solution of an acid. The acid may be sulfuric acid. Under such conditions, the membrane (10) undergoes a dimensional change. This dimensional change is known as swelling. The swelling of the membrane (10) is regulated by the presence of PVDF or PVDF-HFP in the blend (12). The swelling of the membrane (10) can be controlled by changing the mass percentage of PVDF or PVDF-HFP. Another advantage of blending with PVDF or PVDF-HFP is that the membrane (10) can function even in high concentrations of H2SO4, such as above 5M. A combination of PVDF and PVDF-HFP may have a similar effect on swelling and function at high H2SO4 concentrations.

[0057] PBI contains imidazole units. The imidazole units in the polymer backbone of a PBI polymer act as both acidic and basic sites, depending on their chemical environment. For example, when immersed in an acidic medium such as H2SO4 or H3PO4, the PBI film (10) acts as a cation-conducting film (10). This process is called protonation of the film (10). Once protonated, the PBI film (10) repels positively charged ions according to Donnan's exclusion principle. For example, when immersed in a base such as NaOH or KOH, PBI acts as an anion host.

[0058] PVDF and PVDF-HFP are inherently hydrophobic. When blended with PBI, the hydrophobicity of PVDF or PVDF-HFP preferentially causes the imidazole ring to complex with or protonate acid molecules. It is desirable that the membrane (10) has as many active sites as possible. Active sites in the ion-conducting membrane (10) refer to sites on the polymer chain that host active ions. However, if there is an excess of PVDF in the polymer blend (12), the total number of active sites will decrease or the mechanical properties of the membrane (10) will deteriorate. Therefore, the mass percentage of PVDF or PVDF-HFP is maintained to be less than 20%. In some embodiments, additives (14) used in the ion-conducting membrane (10) to be used in a flow cell include graphene oxide, functionalized graphene oxide, or a combination thereof. Graphene oxide and functionalized graphene oxide have a layered structure. OH - NH - 2, and COOH - The functional groups of functionalized graphene oxide, such as those mentioned above, are intercalated between the layers, forming weak bonds with the layers.

[0059] In some embodiments, the ion-conducting membrane (10) can be used in an HT-PEM fuel cell. An HT-PEM fuel cell is a fuel cell that uses hydrogen (H2) as fuel and operates at high temperatures, such as up to 250°C. The ion-conducting membrane (10) used in an HT-PEM fuel cell is intended to have high ionic conductivity for protons and low permeability to hydrogen gas molecules. The ion-conducting membrane (10) used in an HT-PEM fuel cell is desired to have high ionic conductivity for protons at high temperatures, such as up to 250°C, and high mechanical strength, such as high tensile strength at these high temperatures. Since conductance per unit area is inversely proportional to its thickness, the membrane (10) is also desired to have low permeability to H2 molecules because the H2 crossover results in a low open-circuit potential in an HT-PEM fuel cell.

[0060] The HT-PEM fuel cell membrane (10) is typically impregnated with H3PO4 acid to create active sites. The process of impregnating the membrane (10) with acid is also known as "acid-loading" or "acid-uptake." The active sites of the HT-PEM fuel cell membrane (10) are protons (H + This refers to the sites on the polymer chain that host ions, and the free volume of acid trapped within the membrane (10). A membrane (10) with a high acid-filling density has a high active site. A high acid-filling density also softens the membrane (10). Softening of the membrane (10) leads to a deterioration of its mechanical properties. At high temperatures, the deterioration of the mechanical properties of the membrane (10) becomes more severe.

[0061] In some embodiments, the ion-conducting membrane (10) that can be used in the HT-PEM fuel cell contains PVDF, PVDF-HFP, or a combination thereof in a homogeneous blend (12) together with PBI. One of the additives (14) is h-BN. The other additives (14) may be one or more of graphene oxide and functionalized graphene oxide.

[0062] h-BN has a multilayer structure similar to graphene. h-BN consists of alternating boron (B) and nitrogen (N) atoms forming hexagonal rings. Protons can move through the centers of the hexagonal rings in the atomic layers of h-BN, while other larger molecules are blocked. This structure makes the h-BN-containing film (10) impermeable to all chemical species except protons. The centers of the hexagonal rings of BN in the consecutive atomic layers overlap each other. Therefore, the structure of h-BN can be considered "porous" with respect to protons. Melting point T m Because its temperature exceeds 2800°C, h-BN has high thermal stability. Therefore, the film (10) containing h-BN can operate at high temperatures due to its high thermal stability. Due to the high "porous" nature of h-BN with respect to proton conduction, it is possible to increase the mass percentage of the additive (14) in the film (10) and increase the amount of aggregates.

[0063] Due to the layered atomic structure of h-BN contained in the film (10), phosphate molecules can be intercalated between the layers of h-BN. The increased interaction between the nanoadditive (14) and the phosphate molecules reduces acid leaching from the film (10).

[0064] In some embodiments, in an ion-conducting membrane (10) that can be used in an HT-PEM fuel cell, the mass percentage of one or more polymers is in the range of 1% to 20%. The mass percentage of additives (14) is in the range of 1% to 20%. The amount of h-BN is greater than the amount of one or more other additives (14). In some embodiments, the mass of h-BN is more than 10 times greater than the mass of one or more other additives (14). The amount of dispersed material is greater than 90%, and the amount of aggregated material is less than 30%. The conductance per unit area is 1 S / cm at a temperature of 30°C. 2 It is extremely powerful, with a maximum rate of 60 S / cm at a temperature of 200°C. 2 That is the case.

[0065] Electrolytic apparatuses produce hydrogen (H2) gas and (O2) gas from water (H2O). Electrolytic apparatuses that use a membrane (10) to produce H2 may use either a cation exchange membrane (10) or an anion exchange membrane (10). Electrolytic apparatuses using an anion exchange membrane (10) (AEM) are known as AEM electrolytic apparatuses. The electrolyte used in AEM electrolytic apparatuses is a hydroxide. Such hydroxide solutions are also known as alkalis. Alkalis include sodium hydroxide (NaOH) and potassium hydroxide (KOH). The performance of such electrolytic apparatuses depends on the concentration of the alkali solution used. The efficiency of the electrolytic apparatus increases with increasing alkali concentration. The alkali concentrations typically used in electrolytic apparatuses are in the range of 5% to 40%, where this percentage is expressed as the ratio of the mass of alkali to the volume of water. The main limitation of AEMs is the degradation of the membrane (10) at high alkali concentrations.

[0066] The membrane (10) used in AEM is typically made from a polymer functionalized with quaternary amine groups. The quaternization reaction functionalizes the polymer to create an ionogen moiety that enables operation in an alkaline medium. A high concentration of alkaline solution attacks the -NH2 groups of the anion exchange membrane (10) by Hoffmann elimination. Hoffmann decomposition involves the removal of -C=O groups from the polymer backbone in the presence of a strong base.

[0067] The PBI polymer film (10) is operable in highly alkaline solutions. However, highly alkaline solutions soften the PBI polymer. To improve mechanical strength through structural reinforcement, a functionalized GO additive (14) is dispersed in the film (10). Functionalized GO forms OH within the film (10). - It is functionalized to create further active sites and pathways for hosting and transporting the group. Active OH present in GO - The affected area is also susceptible to Hoffmann degradation. The ability of PBI to host higher concentrations of alkaline solutions makes Hoffmann degradation of functionalized GO less likely.

[0068] The ion-conducting membrane (10) disclosed herein may be used in an AEM electrolysis apparatus. In the ion-conducting membrane (10), a functionalized GO additive (14) is dispersed to maximize the number of active sites and the mechanical elasticity of the membrane (10). The mass percentage of the functionalized GO is selected to be in the range of 1% to 80%. In the ion-conducting membrane (10), chitosan, functionalized chitosan, or a combination thereof is used together with PBI to prepare a homogeneous polymer blend (12). The chitosan or functionalized chitosan enhances the PBI-functionalized GO matrix by a continuous network of hydrogen bonds. It acts as a crosslink between the GO nanosheets and the PBI polymer matrix in aqueous solution, resulting in better dispersion of sites and additives (14) within the membrane (10). The mass percentage of the chitosan or functionalized chitosan or a combination thereof in the polymer blend (12) is in the range of 1% to 40%.

[0069] Unlike conventional hydrogen fuel cells, DMFCs typically use diluted methanol in liquid form as fuel. Methanol is diluted with H2O. The methanol concentration in water used in commonly known DMFCs is usually in the range of 1M to 3M. Therefore, the energy density of DMFCs is very low. Due to the crossover of methanol molecules through the membrane (10), high concentrations of methanol cannot be used in DMFCs. A membrane (10) that can prevent the permeation of methanol molecules through the membrane itself can be used in DMFCs with higher concentrations of methanol fuel. In a membrane (10) with sufficiently low methanol permeability, the methanol concentration in the fuel supply can be as high as 15M. Therefore, the membrane (10) to be used in DMFCs should have high ionic conductivity for protons and very low permeability for methanol molecules. The size of a methanol molecule is larger than that of a proton. Methanol crossover through the membrane (10) can be prevented by creating an obstacle to the flow of methanol through the membrane (10). One object of this disclosure is to form a membrane (10) that preferentially provides pathways that offer high resistance to methanol flow but minimal resistance to proton flow.

[0070] In some embodiments, the ion-conducting membrane (10) disclosed herein is suitable for use in DMFCs. Raw material components, compositions, and methods are selected for forming an ion-conducting membrane (10) suitable for use in DMFCs. The ion-conducting membrane (10) disclosed herein is also suitable for use in DMFCs operating at temperatures up to 230°C. PVDF, PVDF-HFP, or a combination thereof is blended with PBI and dispersed with one or more additives (14) selected from the group consisting of h-BN, GO, and functionalized GO to enhance thermal stability, ion conductivity, and mechanical properties. This improves the performance of the DMFC at high temperatures. High-temperature operation allows for DMFC operation with or without a reformer. Higher efficiency can be obtained in DMFCs operating at high temperatures.

[0071] In this specification, the membrane (10) comprises another polymer along with PBI. PVDF, PVDF-HFP, or a combination of PVDF and PVDF-HFP may be used as the other polymer as part of the homogeneous polymer blend (12). The mass percentage of PVDF, PVDF-HFP, or a combination thereof is in the range of 1% to 35%. The membrane (10) comprises one or more additives (14) selected from the group consisting of GO, functionalized GO, and h-BN. The addition of h-BN enables operation at high temperatures. The mass percentage of one or more additives (14) is in the range of 1% to 80%. The membrane (10) has a dispersion amount of more than 90% and an aggregate amount of less than 20%. The conductance per unit area of ​​the membrane (10) is 1 S / cm 2 It is greater than 50 MPa. The tensile strength of the membrane (10) is greater than 50 MPa.

[0072] To achieve low methanol molecule permeability while maintaining high conductance per unit area, the ion-conductive membrane (10) is formed to have a gradient along the flow direction of methanol molecules. The gradient may include a gradient of dispersion or chemical composition. Different gradients that can be conceivable for the dispersion of one or more additives (14) in a polymer blend (12) are shown in Figures 2A, 2B, and 2C. Figure 2A shows a dispersion that varies continuously along the thickness of the membrane (10). Figures 2B and 2C show dispersions that vary along the thickness of the membrane (10) such that the dispersion profile along the thickness of the membrane (10) has valleys and peaks, respectively. The gradient was achieved by forming multiple sub-membranes (10) of different compositions and integrating them to form a monolithic membrane (10). In some embodiments, the ion-conductive membrane (10) includes multiple sub-membranes (10) that are smaller and of varying thicknesses to achieve gradients of conductivity and methanol permeability. The method for forming the membrane (10) is designed to integrate sub-membranes (10) during the process of forming the ion-conducting membrane (10) to form a single monolithic membrane (10). The desired gradient is achieved by varying the raw material components, composition, dispersion amount, and aggregate amount of each sub-membrane (10).

[0073] The physical structures of some components of electrochemical devices can range from simple ones, such as the ion-conducting membrane (10) used in flow batteries, to complex ones, such as membrane (10) electrode assemblies (MEAs) or membrane (10) with catalyst layers (CCMs) used in fuel cells. The physical structures of components in some electrochemical devices, such as advanced metal batteries, can be far more complex than those of fuel cells. The challenges always relate to the properties of the activating species and the components that handle those activating species.

[0074] In advanced metal batteries, higher energy density is achieved than in conventional lithium-ion batteries by using metallic lithium as the anode. In lithium metal batteries, metallic lithium is used as the anode instead of graphite, which is intercalated with lithium ions. In advanced lithium metal batteries, sulfur is used as one of the cathode components. Sulfur is not an intercalation compound like graphite. Other components used in advanced metal batteries are often selected from conventional technologies due to the difficulty in obtaining suitable components. For example, lithium-sulfur batteries still use a liquid electrolyte along with a separator. Sulfur used as the cathode tends to form polysulfides such as Li2S, Li2S2, Li2S3, Li2S4, Li2S6, Li2S8, and S8. These polysulfides are, in fact, part of the battery's active material. When the active material migrates to the electrolyte, the battery capacity decreases, resulting in capacity degradation. The formation of metallic lithium dendrites that can penetrate the separator is another significant challenge for lithium-sulfur batteries.

[0075] Electrochemical devices such as aluminum-air batteries, also known as aluminum-air fuel cells, face the significant challenge of aluminum electrode corrosion. Some other electrochemical devices, such as those used to extract metallic lithium from saline solutions, utilize solid electrolytes. Solid electrolytes exposed to highly corrosive saline environments are susceptible to accelerated degradation. The component (100) disclosed herein is designed to address the aforementioned challenges associated with one or more electrochemical devices.

[0076] Some of the components (100) disclosed herein necessarily include a membrane (10) and one or more types of physical structures. The physical structures may include layers of nanofibers (22) used in conjunction with the membrane (10), electrodes, solid electrolytes, or interfacial layers. The raw materials, composition, and formation methods of the membrane (10) and physical structures in different embodiments may vary depending on the application.

[0077] In a particular embodiment, a component (100) is disclosed that includes a film (10) with layers of nanofibers (22) adjacent to each other on both sides. The adjacency of the layers of nanofibers (22) can be integrated with the largest surface of the film (10) oriented perpendicular to the flow of ions / molecules through the film (10).

[0078] In a particular embodiment, a component (100) is disclosed in which two membranes (10) are adjacent to each other on both sides of a layer of nanofibers (22). This adjacency occurs on the largest surface side of the membranes (10), which is also typically perpendicular to the flow of ions / molecules through the membranes (10).

[0079] In certain other embodiments, a component (100) is disclosed in which the device electrodes are adjacent to one side of the film (10) and a layer of nanofibers (20) is adjacent to the opposite side of the film (10). This adjacency is made on the side of the largest face of the film (10) that is perpendicular to the flow of ions / molecules through the film (10). One such embodiment is shown in Figure 3C.

[0080] The membrane (10) described in almost all of the embodiments above comprises a homogeneous blend (12) of PBI and one or more polymers selected from the group consisting of PVDF, PVDF-HFP, chitosan, and functionalized chitosan. The mass percentage of one or more polymers is in the range of 1% to 40%. One or more additives (14) selected from the group consisting of graphene oxide, functionalized graphene oxide, and h-BN are used. The mass percentage of one or more additives (14) is in the range of 0.5% to 80%. The additives (14) are dispersed in the polymer blend (12) in a dispersion amount of more than 80% and an aggregate amount of less than 30%. The ion conductance per area of ​​the membrane (10) is 1 S / cm at 30°C. 2 It's incredible.

[0081] Figure 3A shows a component (100) comprising an ion-conductive membrane (10) and two nanofiber layers (20). The membrane (10) acts as a thin, dense interlayer sandwiched between the two porous nanofiber layers (20). This type of physical structure of the component may be advantageous in the case of metal electrode flow batteries, where the outer nanofibers (22) can absorb more electrolyte, because the nanofibers (22) allow ions to have more accessible conduction pathways. The dense interlayer acts as a barrier against inactive ions. When a stack is fabricated, the membrane (10) needs to be able to withstand compressive forces so as not to rupture or develop pinhole defects in the thickness direction. The outer porous nanofiber layers (20) can withstand compressive forces and prevent direct punctures in the internal dense interlayer. The component (100) shown in Figure 3A may be used in electrochemical devices, including electrolysis devices, advanced metal batteries, and flow batteries.

[0082] A method for forming component (100) includes the following steps: In the first step, a preforming solution of a first viscosity is prepared containing a homogeneous polymer solution and an additive (14) dispersion. In the second step, a porous, independent nanofiber layer (20) is formed by electrospinning the preforming solution of the first viscosity. In the third step, the solvent in the porous nanofiber layer (20) is partially removed. In the fourth step, another preforming solution of a second viscosity suitable for spray coating is prepared. In the fifth step, the preforming solution of the second viscosity is sprayed onto one surface of the nanofiber layer (20). This forms a thin, dense sheet of polymer additive (14) blend (12) on the nanofiber layer (20). In the sixth step, the solvent is partially removed from the thin, dense sheet. In the seventh step, the preforming solution of the first viscosity is electrospinned onto the formed thin, dense sheet. Finally, all residual solvent is removed from this physical structure, and the desired component is formed.

[0083] Depending on the application, the raw material components and composition of the preforming solution may be adjusted to form a structure that is asymmetrical with respect to a plane passing through the center of the film (10). The plane of symmetry referred to herein is coplanar with the maximum surface area plane of the film (10). The ionic conductivity properties of the film (10) and the nanofiber layer (20) can be adjusted by changing the raw material components and composition of the preforming solution.

[0084] Figure 3B shows one example of a component (100) having two ion-conductive membranes (10) and a porous nanofiber layer (20). The nanofiber layer (20) is sandwiched on both sides by the two dense ion-conductive membranes (10). This type of membrane (10) arrangement may be useful in high-temperature fuel cells, alkaline fuel cells, and alkaline electrolysis devices where maintaining ion conductivity is a critical requirement. The porous core (20) acts as a host for the electrolyte (acidic or basic medium), thereby increasing conductance per unit area by trapping more strong acids or bases within it. Since fibers are stronger than films, high acid or base filling can be achieved by the fibers. These fibers are then trapped in the dense layer, which plays a dual role: retaining more acids or bases inside the membrane (10) and acting as an external permeability barrier. The dense outer layer enables more stable performance over long periods by reducing electrolyte leaching.

[0085] A method for forming the component (100) shown in Figure 3B includes the following steps: In the first step, pre-forming solutions of different first, second, and third viscosities are prepared as described above. In the second step, a porous, independent nanofiber layer (20) is formed by electrospinning the pre-forming solution of the first viscosity. In the third step, the solvent in the porous nanofiber layer (20) is partially removed. In the fourth step, a pre-forming solution of the second viscosity, suitable for spray coating, is sprayed onto the nanofiber layer (20). In the fifth step, the solvent is partially removed. In the sixth step, a pre-forming solution of the third viscosity is sprayed onto multiple surfaces of the nanofiber layer (20) to form a second sheet. In the seventh step, the residual solvent is removed to form the desired component.

[0086] In some embodiments, the sheet formation techniques in the fourth and sixth steps may be replaced by other sheet formation techniques, such as dip coating. In some other embodiments, the sheet formation techniques in the fourth and sixth steps may be replaced by other sheet formation techniques, such as solution casting. Depending on the application, the raw material components and composition of the preforming solution may be adjusted to form a structure that is asymmetric with respect to the plane passing through the center of the porous layer. The ionic conductivity properties of the membrane (10) and the nanofiber layer (20) can be adjusted by changing the raw material components and composition of the preforming solution.

[0087] Figure 3C shows a component (100) in which a device electrode (30) is adjacent to one side of a film (10) and a layer of nanofibers (20) is adjacent to the opposite side. This adjacency is made on the largest surface side of the film (10), perpendicular to the flow of ions / molecules through the film (10). The component may have high conductivity to ions including protons, lithium ions, and aluminum ions. The component may also have high conductivity to polysulfides, metal ions other than lithium, such as sodium ions (Na). + ), hydroxyl ion (OH - ), and may have low transmittance to chemical species containing magnesium ions.

[0088] A method for forming the component (100) shown in Figure 3C includes the following steps: In the first step, pre-forming solutions of first and second viscosities are prepared as described above. In the second step, the solution of first viscosity is sprayed directly onto a substrate to form a sheet. The substrate (30) may include electrodes, solid electrolytes, and other interfacial layers of an electrochemical device. In the third step, the solvent in the sheet is partially removed. In the fourth step, the pre-forming solution of second viscosity is electrospinned onto the surface of the sheet for the purpose of forming a nanofiber layer (20). In the final step, the residual solvent is completely removed. In some embodiments, the sheet is formed on a selected substrate by a solution casting method or dip coating.

[0089] According to various embodiments of the present disclosure, additives (14) of different length scales may be incorporated into the polymer blend (12) in any suitable shape or size as shown in Figure 4A. The nanofiber mat (20) shown in Figure 4B may also be made of a number of nanofibers (22), which in various embodiments may also include additives (14) in the matrix forming the nanofiber mat (20). [Examples]

[0090] In one experiment, 9.6 g of PBI and 1.06 g of PVDF were dissolved in 61.79 g of DMAc in a glass beaker on a hot plate equipped with a magnetic stirrer. The temperature was slowly raised from room temperature to 140°C over 16 hours while stirring to form a homogeneous solution of the polymer. In a parallel experiment, 0.19 g of graphene oxide was dispersed in 7 g of DMAc by sonication and subsequent stirring at room temperature to form an additive dispersion.

[0091] Furthermore, the additive dispersion was added to the homogeneous polymer solution and mixed to form a pre-forming solution. Next, the pre-forming solution was cast onto a glass plate using the doctor blade method to form a sheet. This sheet was heated to 150°C to remove the solvent and form a film (10). The film (10) was then peeled off the substrate using water.

[0092] The thickness of the film (10), measured using a screw gauge, was 40 μm. The film (10) was further characterized for transmittance, dispersion amount, aggregate amount, and conductivity.

[0093] The permeability of membrane (10) was measured as shown in So-Won Choi, et. al. “Hydrocarbon membranes (10) with high selectivity and enhanced stability for vanadium redox flow battery applications: Comparative study with sulfonated poly(ether sulfone)s and sulfonated poly(thioether ether sulfone)s”, Electrochimica Acta, vol. 259, pp. 427-439 (2018).

[0094] Simply put, it has a thickness of 40 μm and a cross-sectional area of ​​1.847 cm². 2 The membrane (10) was attached to a cell having two compartments. One compartment contained 35 ml of a solution of VOSO4·5H2O salt in 2 M H2SO4. The concentration of VOSO4·5H2O salt in the 2 M H2SO4 solution was 1.66 M. The other compartment contained 35 ml of a solution of MgSO4 salt in 2 M H2SO4. The concentration of MgSO4 salt in the 2 M H2SO4 solution was 1.66 M. The membrane (10) was placed between the two solutions to allow ion flow from both compartments to each other. The solution containing MgSO4 was continuously stirred for 48 hours. After 48 hours, V 4+ To determine the ion concentration, the solution in the MgSO4 compartment was analyzed using a UV-Vis spectrophotometer. 4+ The ion concentration was determined to be 0.00282 M. The permeability of the membrane (10) was 5.03 × 10⁻⁶. -8 cm 2 It was identified as / minutes.

[0095] To measure the ionic conductivity of the membrane (10), a flow cell was constructed as shown in M. Raja, et.al, “Binder-free thin graphite fiber mat sandwich electrode architectures for energy-efficient vanadium redox flow batteries”, Catalysis Today, vol. 370, pp 181-188 (2021).

[0096] For ionic conductivity measurements, a 40 μm thick, square film (10) with dimensions of 7 cm x 7 cm was used. The effective area of ​​film (10) was 25 cm². 2 The membrane (10) was pre-treated with 3M H2SO4 for 2 hours before being incorporated into the flow cell. For measurement, 3M H2SO4 was circulated into the flow cell using a peristaltic pump. Electrochemical impedance spectroscopy (EIS) measurements were performed on the flow cell in the frequency range of 200 kHz to 100 mHz. The real part of the membrane (10) impedance, with the imaginary impedance set to zero, was considered as the membrane (10) resistance. Conductivity was calculated from the resistance value. In one measurement, the membrane (10) resistance was 63 mΩ. The conductance per unit area was 635 mS / cm². 2 The ionic conductivity was calculated to be 2.54 mS / cm. The selectivity was 5.04 × 10⁻⁶. 4 S×min / cm 3 It was calculated to be this.

[0097] Tensile tests for the ionic conductivity of the film (10) were performed as described in ASTM D882-18, Standard Test Method for Tensile Properties of Thin Plastic Sheeting, ASTM International, West Conshohocken, PA, (2018).

[0098] A clean, dry film (10) with a thickness of 40 μm was cut into strips 300 mm long and 6 mm wide. The gauge length of the sample was 250 mm. The sample was fixed to a universal testing machine with a 100 N load cell. Uniaxial tensile testing was performed at a strain rate of 25 mm / min, as recommended by the standard. The tensile strength (UTS) was calculated using the maximum load obtained from the tensile test. In one measurement, the UTS was calculated to be 42 MPa.

[0099] The ion-conducting membranes (10) disclosed in this invention and related devices incorporating these membranes (10) can improve the ionic conductivity of desired ions while simultaneously blocking the transport of undesirable chemical moieties. By selecting additives (14) to the polymer blend (12), the membranes (10) can be designed to have the transport properties desired for their application in electrochemical systems. For applications in devices with acidic or basic operating conditions, both the polymer blend (12) and the additives (14) can be selected and adjusted to achieve either anionic or cationic transport.

[0100] Although this disclosure has been described using specific language, no limitations are intended to arise as a result thereof. As will be apparent to those skilled in the art, various operational modifications may be made to the method for the purpose of carrying out the concept of the invention taught herein.

[0101] The drawings and the above description provide examples of embodiments. Those skilled in the art will understand that one or more of the elements described may well be combined into a single functional element. Alternatively, a particular element may be divided into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the order of the methods described herein may be changed and is not limited to those described herein. Furthermore, the operations in any flowchart do not need to be performed in the order shown, nor do all operations necessarily need to be performed. Also, operations that are independent of other operations may be performed in parallel with other operations. The scope of the embodiments is not limited in any way by these specific examples. Numerous modifications are possible, whether expressly shown herein or not, including differences in structure, dimensions, and the use of materials. The scope of the embodiments is at least as broad as shown in the following claims.

[0102] (Note) As a preferred embodiment, the technical concept that can be understood from the above embodiment is described below. [Item 1] An ion-conducting film (10), (a) A homogeneous blend (12) of polybenzimidazole (PBI) and one or more polymers selected from the group consisting of polyvinylidene difluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), chitosan, and functionalized chitosan, wherein the mass percentage of the one or more polymers is in the range of 1% to 40% relative to the mass of PBI, and (b) One or more additives (14) selected from the group consisting of graphene oxide, functionalized graphene oxide, and hexagonal boron nitride (h-BN), wherein the mass percentage is in the range of 0.5% to 80% relative to the mass of PBI. Includes, The additive (14) is dispersed in the homogeneous blend (12) with a dispersion amount of more than 80% and an aggregate amount of less than 30%, and the ion conductance per unit area of ​​the ion-conducting membrane (10) is 1 S / cm at 30°C. 2 An ion-conducting film (10) is super. [Item 2] The material comprises one or more polymers selected from the group consisting of PVDF, PVDF-HFP, or combinations thereof, wherein the mass percentage of the one or more polymers is in the range of 1% to 20% relative to the mass of PBI, and The additive (14) comprises h-BN and one or more additives (14) selected from the group consisting of graphene oxide and functionalized graphene oxide, the total mass percentage of the h-BN and the one or more additives (14) combined is in the range of 1 to 20% of the mass of PBI, the mass of h-BN is 10 times the mass of the one or more additives (14), the amount of dispersed material of the one or more additives (14) is more than 90%, and the amount of aggregated material of the additives (14) is less than 30%, and The ion conductance per unit area of ​​the aforementioned film (10) is 1 S / cm² at 30°C. 2 It is extremely powerful, with a maximum rate of 60 S / cm at a temperature of 200°C. 2 The ion-conducting film (10) described in item 1. [Item 3] One or more polymers selected from the group consisting of chitosan and functionalized chitosan, wherein the mass percentage is in the range of 2% to 40% relative to the mass of PBI, and The one or more additives (14) comprising functionalized graphene oxide, wherein the mass percentage is in the range of 1% to 80% relative to the mass of PBI, The amount of dispersed material of the one or more additives (14) is greater than 90%, and the amount of aggregated material of the one or more additives (14) is less than 10%, and The ion conductance per unit area of ​​the aforementioned film (10) is 1 S / cm² at 30°C. 2 An ion-conducting film (10) as described in item 1, having a tensile strength of more than 50 MPa. [Item 4] The polymer comprises one or more polymers selected from the group consisting of PVDF and PVDF-HFP, wherein the mass percentage is in the range of 1% to 35% relative to the mass of PBI. The additive (14) comprises h-BN and one or more additives (14) selected from the group consisting of graphene oxide and functionalized graphene oxide, and the total mass percentage of the h-BN and the one or more additives (14) combined is in the range of 1 to 80% of the mass of PBI. The amount of dispersed material of the additive (14) is more than 90%, and the amount of aggregated material of the one or more additives (14) is less than 20%. The ion conductance per unit area of ​​the aforementioned film (10) is 1 S / cm² at 30°C. 2 It is greater than 50 MPa, and its tensile strength is greater than 50 MPa. The ion-conducting membrane (10) according to item 1, wherein the membrane (10) has a gradient in the size, shape, quantity, or combination thereof of the one or more additives (14), and the gradient is perpendicular to the maximum region of the membrane (10). [Item 5] A component (100) comprising an ion-conducting film (10), wherein the ion-conducting film (10) is (a) A homogeneous blend (12) of polybenzimidazole (PBI) and one or more polymers selected from the group consisting of polyvinylidene difluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), chitosan, and functionalized chitosan, wherein the mass percentage of the one or more polymers is in the range of 1% to 40% relative to the mass of PBI, and (b) One or more additives (14) selected from the group consisting of graphene oxide, functionalized graphene oxide, and hexagonal boron nitride (h-BN), wherein the mass percentage is in the range of 0.5% to 80% relative to the mass of PBI. The additives (14) are dispersed in the blend (12) in an amount of more than 80% dispersed material and less than 30% aggregated material, and the ion conductance per unit area of ​​the membrane (10) is 1 S / cm² at 30°C. 2The component is super (100). [Item 6] The component (100) according to item 5, wherein layers of nanofibers (20) are adjacent to both sides of the ion-conducting membrane (10), each in a direction perpendicular to the flow of ions passing through the ion-conducting membrane (10). [Item 7] The component (100) according to item 5, wherein one ion-conductive film (10) is adjacent to a layer of nanofibers (20) from one side of the layer, and another ion-conductive film (10) is adjacent to the layer of nanofibers (20) from the opposite side, in a direction perpendicular to the flow of ions through the ion-conductive films (10). [Item 8] The component (100) according to item 5, wherein a substrate is adjacent to one side of an ion-conducting film (10), and a layer of nanofibers (20) is adjacent to the opposite side, in a direction perpendicular to the flow of ions passing through the ion-conducting film (10). [Item 9] A method for producing an ion-conducting film (10), A homogeneous polymer solution is formed by dissolving a polybenzimidazole (PBI) polymer and one or more polymers selected from the group consisting of polyvinylidene difluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), chitosan, and functionalized chitosan in one or more solvents selected from the group consisting of N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), phosphoric acid, polyphosphate, formic acid, KOH, and ethanol, wherein the mass percentage of the selected one or more polymers is in the range of 1% to 40% relative to the mass of PBI. Forming an additive dispersion by dispersing one or more additives (14) selected from the group consisting of graphene oxide, functionalized graphene oxide, and hexagonal boron nitride (h-BN) in the one or more solvents, wherein the mass percentage of the one or more additives (14) is in the range of 0.5% to 80% relative to the mass of PBI. The polymer solution and the additive dispersion are homogeneously mixed to obtain a preliminary forming solution. Forming a sheet, and The solvent is removed to obtain the ion-conducting film (10). The additive (14) is dispersed in the ion-conducting membrane (10) with a dispersion amount of more than 80% and an aggregate amount of less than 30%, and the ion conductance per unit area of ​​the membrane (10) is 1 S / cm² at 30°C. 2 A method for producing an ion-conducting film (10). [Item 10] The selection of one or more polymers from the group consisting of PVDF and PVDF-HFP, wherein the mass percentage of the one or more polymers is in the range of 1% to 20% relative to the mass of PBI. The PBI and the one or more selected polymers are dissolved in one or more solvents selected from the group consisting of DMAc, DMF, DMSO, NMP, THF, phosphoric acid, polyphosphate, formic acid, KOH, and ethanol to form the homogeneous polymer solution, wherein the mass ratio of the solid content to the liquid content in the polymer solution is less than 0.2. The process involves selecting one or more additives (14) from the group consisting of graphene oxide and functionalized graphene oxide, and dispersing them in one or more solvents to form an additive dispersion, wherein the mass percentage of the one or more additives (14) is in the range of 0.5% to 10% relative to the mass of PBI. The homogeneous polymer solution and the additive dispersion are mixed by stirring and ultrasonic treatment to form the pre-forming solution. The aforementioned pre-forming solution is solution-cast to form a sheet, and Removing one or more of the aforementioned solvents, The method described in item 9, including the method described in item 9. [Item 11] The selection is made by choosing PVDF, PVDF-HFP, or a combination thereof, wherein the mass percentage of the one or more polymers relative to the PBI is in the range of 1% to 20% relative to the mass of the PBI. The PBI and the one or more selected polymers are dissolved in one or more solvents selected from the group consisting of DMAc, DMF, DMSO, NMP, THF, phosphoric acid, polyphosphate, formic acid, KOH, and ethanol to form the homogeneous polymer solution, wherein the mass ratio of the solid content to the liquid content in the polymer solution is up to 0.2. The selection involves selecting h-BN and one or more additives (14) selected from the group consisting of graphene oxide and functionalized graphene oxide, wherein the total mass percentage of the h-BN and the one or more additives (14) combined is in the range of 1% to 20% of the mass of PBI, and the mass of the h-BN is 10 times or more the mass of the other one or more additives (14). The process involves dispersing the h-BN in one or more solvents and dispersing one or more additives (14) to form an additive dispersion, wherein the mass ratio of the one or more additives (14) to the selected one or more solvents is at most 2:98. The homogeneous polymer solution and the additive dispersion are mixed by stirring and ultrasonic treatment to form the pre-forming solution. The aforementioned pre-forming solution is solution-cast to form a sheet, and Removing one or more of the aforementioned solvents, The method described in item 9, including the method described in item 9. [Item 12] The selection of chitosan, functionalized chitosan, or a combination thereof, wherein the mass percentage of chitosan, functionalized chitosan, or a combination thereof is within the range of 2% to 40% relative to the mass of PBI. The selected polymer and PBI are dissolved in one or more solvents selected from the group consisting of DMAc, DMF, DMSO, NMP, THF, phosphoric acid, polyphosphate, formic acid, KOH, and ethanol to form the homogeneous polymer solution, wherein the mass ratio of the solid content to the liquid content in the polymer solution is up to 0.2. Selecting one or more additives (14) containing functionalized graphene oxide, wherein the mass percentage of the one or more additives (14) is in the range of 1% to 80% relative to the mass of PBI. Dispersing the one or more additives (14) in the one or more solvents to form the additive dispersion, The homogeneous polymer solution and the additive dispersion are mixed by stirring and ultrasonic treatment to form the pre-forming solution. The aforementioned pre-forming solution is solution-cast to form a sheet, and Removing one or more of the aforementioned solvents, The method described in item 9, including the method described in item 9. [Item 13] (a) Selecting PVDF, PVDF-HFP, or a combination thereof, wherein the mass percentage of the one or more polymers is in the range of 1% to 35% relative to the mass of PBI. (b) Dissolving the PBI and the one or more selected polymers in one or more solvents selected from the group consisting of DMAc, DMF, DMSO, NMP, THF, phosphoric acid, polyphosphate, formic acid, KOH, and ethanol to form the homogeneous polymer solution, wherein the mass ratio of the solid content to the liquid content in the polymer solution is up to 0.2. (c) Selecting one or more additives (14) from the group consisting of graphene oxide, functionalized graphene oxide, and h-BN, wherein the mass percentage of the one or more additives (14) is in the range of 1% to 80% of the mass of PBI. (d) Dispersing the selected additive (14) in the one or more solvents to form the additive dispersion, wherein the mass percentage of the one or more additives (14) is in the range of 1% to 80% relative to the mass of PBI. (e) Mixing the homogeneous polymer solution and the additive dispersion by stirring and ultrasonic treatment to form the pre-forming solution. (f) Form a sheet by solution casting the pre-forming solution, and partially remove the one or more solvents. (g) Repeat steps (a) to (f) to stack the sheets until the number of sheets reaches a predetermined number, and independently vary the mass ratio of the polymer to PBI and the mass ratio of the additive (14) to PBI to form multilayer films (10) with different additive (14) contents, and at the same time maintain in all the layers that the amount of dispersed material is greater than 90% and the amount of aggregated material is less than 10%, and (h) Completely remove all residual solvents. The method described in item 9, including the method described in item 9. [Item 14] A method for manufacturing a component (100) having an ion-conducting film (10), wherein the method is: A homogeneous polymer solution is formed by dissolving a polybenzimidazole (PBI) polymer and one or more polymers selected from the group consisting of polyvinylidene difluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), chitosan, and functionalized chitosan in one or more solvents selected from the group consisting of N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), phosphoric acid, polyphosphate, formic acid, KOH, and ethanol, wherein the mass percentage of the selected one or more polymers is in the range of 1% to 40% relative to the mass of PBI. Forming an additive dispersion by dispersing one or more additives (14) selected from the group consisting of graphene oxide, functionalized graphene oxide, and hexagonal boron nitride (h-BN) in the one or more solvents, wherein the mass percentage of the one or more additives (14) is in the range of 0.5% to 80% relative to the mass of PBI. The polymer solution and the additive dispersion are homogeneously mixed to obtain a preliminary forming solution. Forming a sheet from the aforementioned pre-forming solution, and The solvent is removed from the sheet to obtain the ion-conducting film (10). The additive (14) is dispersed with a dispersion amount of more than 80% and an aggregate amount of less than 30%, and the ion conductance per unit area of ​​the membrane (10) is 1 S / cm² at 30°C. 2 A method that is super. [Item 15] The viscosity of the pre-forming solution is controlled within the range of 20 centipoise to 3000 centipoise by independently varying the ratio of polymer to solvent in the polymer solution and the ratio of additive (14) to solvent in the additive dispersion. A method for forming the component (100) described in item 14, including the method described in item 14. [Item 16] The pre-forming solution of the first viscosity is electrospinned to form one independent layer (20) of nanofibers. The pre-forming solution of the second viscosity is sprayed onto the independent layers (20) of the nanofibers to form the sheet, and The first viscosity pre-forming solution is electrospinned on the sheet on the side opposite to the independent layer (20) of nanofibers to form a second layer (20) of nanofibers. The removal of the solvent includes partially removing the solvent after each step of forming the individual layers of the component, and completely removing the solvent after the formation of the component is complete, and The method for forming the component (100) according to item 15, wherein the component (100) is an ion-conductive film (10) having two layers (20) of nanofibers adjacent to each other on the side with the largest surface area, and each layer (20) is located on one side of the ion-conductive film (10). [Item 17] The pre-forming solution of the first viscosity is electrospinned to form a layer of nanofibers (20), and the solvent is partially removed. The pre-forming solution of the second viscosity is sprayed or dipped onto the surface having the maximum surface area of ​​the nanofiber layer (20), and the solvent is partially removed. Repeat the spray or dip coating process on the opposite side of the nanofiber layer (20), and To completely remove the aforementioned solvent, A method for forming the component (100) according to item 15, wherein the component (100) comprises two ion-conducting films (10) adjacent to a layer of nanofibers (20). [Item 18] The pre-forming solution of the first viscosity is sprayed or dipped onto the surface of the substrate (30) to form a sheet of ion-conductive film (10). The pre-forming solution of the second viscosity is electrospinned to form a layer of nanofibers (20) on the surface of the sheet, and To remove the aforementioned solvent, The removal of the solvent includes partially removing the solvent after each step of forming the individual layers of the component (100), and completely removing the solvent after the formation of the component (100) is complete, and A method for forming the component (100) according to item 15, wherein the ion-conducting film (10) is adjacent to the substrate on its largest surface on one side and adjacent to the nanofiber layer (20) on the opposite side. [Item 19] A manufactured article comprising an ion-conducting membrane (10) as described in any one of items 1 to 4. [Item 20] The manufactured articles described in item 19, The manufactured article includes an electrochemical system, The electrochemical system includes a redox flow battery, a high-temperature proton exchange membrane fuel cell, an electrolysis device, a direct steam fuel cell, a direct methanol fuel cell, a high-temperature direct steam fuel cell, a high-temperature direct methanol fuel cell, an alkaline earth metal battery, a fuel cell, or a battery, and is a manufactured article.

Claims

[Claim 1] The invention described in the specification.

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