Methods to Improve Proton Conductivity in Fuel Cell Membranes

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) have become one of the important development directions of PEMFCs because of their outstanding features, including fast reaction kinetics, high tolerance against impurities in fuel, and easy heat and water management. The proton exchange membrane (PEM), as the core component of HT-PEMFCs, plays the most critical role in the performance of fuel cells. Phosphoric acid (PA)-doped membranes have showed satisfied proton conductivity at high-temperature and anhydrous conditions, and significant advancements have been achieved in the design and development of HT-PEMFCs based on PA-doped membranes. However, the persistent issue of HT-PEMFCs caused by PA leaching remains a challenge that cannot be ignored. This paper provides a concise overview of the proton conduction mechanism in HT-PEMs and the underlying causes of PA leaching in HT-PEMFCs and highlights the strategies aimed at mitigating PA leaching, such as designing crosslinked structures, incorporation of hygroscopic nanoparticles, improving the alkalinity of polymers, co... Read More

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Proton exchange membrane fuel cells (PEMFCs) are a highly efficient energy producing device that stands as a novel approach to sort out the energy demand faced by the world. The proton exchange membrane plays a significant role for the function of PEMFCs. Possessing dual functional behavior for ease of proton transfer which other aromatic polymers fail to own naturally has made the triazole moiety a unique PEM material. The material's elevated self-dissociation capability, facilitating proton conduction, coupled with its high dielectric constant led to an increased demand for its application, highlighting its significance in various usage scenarios. For instance, by self-diffusion, 1H-1,2,3-triazole and 1H-1,2,4-triazole materials exhibited conductivities of 1.3 104 and 1.5 104 S/cm, respectively, in their pure forms. Various research groups utilize the triazole molecule as an ionic cross-linker, as a source for the introduction of functional groups, and as a dopant that eventually increases the proton conductivity. This review focuses on the advantages and different proton con... Read More

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High temperature proton exchange membrane fuel cells (HT-PEMFCs) are a promising energy conversion technology due to their quick reaction kinetics, high tolerance to CO impurities, and ease of heat and water management. Nevertheless, the practical implementation of this technology is limited since traditional proton exchange membranes (PEMs) exhibit significantly reduced performance at high temperatures and low humidity. In this extreme situation, researchers have concentrated on investigating new membranes through the creation of novel polymers and fillers or by suggesting sophisticated modification processes, with the goal of attaining high proton conductivity, stable mechanical properties, and tremendous temperature tolerance. This Review focuses on the latest advancements in four PEM domains: (1) perfluorosulfonic acid (PFSA)-based PEMs; (2) aromatic polymer-based PEMs; (3) polybenzimidazole (PBI)-based PEMs; and (4) polymer of intrinsic microporosity (PIM)-based PEMs. We describe and provide an overview of the preparation methods, mechanistic analysis, and core characteristics (... Read More

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The Proton-Exchange Membrane Fuel Cell (PEMFC) has the potential to enable hydrogen worldwide as a clean energy storage medium. However, before it can be implemented globally, the PEMFC needs to be optimized with innovative technology to maximize its efficiency. This investigation will analyze the methods in which the efficiency can be optimized through a different polymer material that can be used as solid polymer electrolyte membrane in the PEM fuel cell, comparing Nafion with Sulfonated Poly (ether ether ketone) as the most effective electrolyte membrane by efficiency.

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Abstract Fuel cells have become a prominent research focus in the realm of clean energy, owing to their attributes of environmental sustainability, high efficiency, and renewable potential. The catalytic activity of electrode materials and the characteristics of proton exchange membranes are considered pivotal determinants of fuel cell performance. Plasma is abundant in highenergy electrons and active species, proven to be a rapid, facile, and green approach for the preparation and treatment of catalytic materials and polymers. This review presents recent applications of plasma technology in proton exchange membrane fuel cells across four key dimensions: cathodes, anodes, proton exchange membranes, and process enhancement, including the preparation and treatment of noble metal catalysts, nonnoble metal catalysts, nonmetal catalysts, and polymer membranes. Furthermore, critical issues of plasma technology applied in PEMFCs were also discussed.

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Proton exchange membrane fuel cells (PEMFCs) have the potential to tackle major challenges associated with fossil fuel-sourced energy consumption. Nafion, a perfluorosulfonic acid (PFSA) membrane that has high proton conductivity and good chemical stability, is a standard proton exchange membrane (PEM) used in PEMFCs. However, PEM degradation is one of the significant issues in the long-term operation of PEMFCs. Membrane degradation can lead to a decrease in the performance and the lifespan of PEMFCs. The membrane can degrade through chemical, mechanical, and thermal pathways. This paper reviews the different causes of all three routes of PFSA degradation, underlying mechanisms, their effects, and mitigation strategies. A better understanding of different degradation pathways and mechanisms is valuable in producing robust fuel cell membranes. Hence, the progress in membrane fabrication for PEMFC application is also explored and summarized.

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Proton exchange membrane fuel cells (PEMFCs) that operate under low-humidity conditions enable the downsizing or elimination of humidifiers. Herein, we report a catalyst layer prepared by adding a highly water-retaining and proton-conducting sulfobetaine-based zwitterionic polymer, synthesized by precipitation polymerization, to a Pt/C catalyst. The prepared PEMFC exhibits a highly efficient cell performance and high durability at low humidity. The membrane containing the optimal amount of poly(sulfobetaine methacrylate) (pSBMA) has an ionic conductivity of 8.8 mS cm1 (90%) under controlled conditions at 19% relative humidity (RH). The optimal pSBMA-containing electrode assembly exhibits a current density of 0.59 A cm2 at 0.6 V and 19% RH, as well as excellent performance stability, retaining 98% of its initial performance after 75 h of durability testing. The findings of this study may provide useful design considerations for fuel-cell systems.

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Abstract The fuel cell carries the promise of being ecologically beneficial and being one of the renewable energy choices. Solid acids have superprotonic behavior, allowing them to act as conductors. It can operate at high temperatures. Hydration, on the other hand, can be employed to increase the solid acid and performance. Furthermore, the size of the electrolyte membrane influences the conductivity, stability, and crystal structure of the fuel cell solid acid compounds. Very few studies have been conducted on solid acid fuel cells, which are still being researched in order to make them feasible as well as a trustworthy alternative to clean renewable energy. This review presents an outline of the variables or attributes and current challenges that influence the technical efficacy and performance of the unique superprotonic conductors for solid acid fuel cells.

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An overview of the state of the art related to proton conducting membrane, its structure, performance, and durability for proton-exchange membrane fuel cells (PEMFCs) is presented. In particular, we discuss (1) causes of membrane failure/degradation in PEMFCs; (2) degradation reactions of perfluorosulfonic acid (PFSA) membranes as revealed by exposure of model compounds to peroxide in the presence of active metals and ultraviolet irradiation (3) currently emerging mitigation techniques, specific membrane degradation mechanisms and latest developments (4) applications of membranes in real PEM fuel call and (5) cost projections as set by DOE, USA. Lastly we close with some brief comments on future prospects, notably the need for similar mechanistic elucidation of non-PFSA membranes.

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The challenges related to the proton exchange membrane (PEM) of proton exchange membrane fuel cells and direct methanol fuel cells are high swelling, loss of mechanical structure strength and high fuel crossover at elevated temperatures that cause low efficiency. The single polymer membrane may replace the commercial membrane with its dimensional stability and low swelling but it shows low proton conductivity. Hydrophilic additives such as polymers and nanomaterials increase the strength of the single polymer membrane internal channels through interaction and lockdown the swelling while maintaining proton conduction through the Grotthuss and Vehicular methods. However, these additives still have limited capability of enhancing attributes of PEM such as limited water absorption, proton conductivity and loose interaction with the single polymer membrane due to their limited or weak functional groups. Hydrophilic group functionalization such as sulfonic groups, phosphonic groups, amino acid groups, carboxylic groups, zwitterionic groups, silane groups and acid doping with additives furt... Read More

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MOF-assisted proton conduction mechanism in the membrane electrolyte and fuel cell performance.

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High-temperature proton exchange membrane fuel cells (HT-PEMFCs) have attract much attention from academic and industry, which can improve the catalyst activity, reduce Pt loading, enhance CO tolerance, and simplify water and heat management. High-temperature proton exchange membrane (HT-PEM) is the key component for HT-PEMFCs. Here, we provide an investigation of newly developed HT-PEM to evaluate its properties and performances in fuel cells above 90 C. The HT-PEM exhibits an excellent proton conductivity of 136.1 mS cm1 at 90 C and 95% RH, and remarkable power density of 0.95 Wcm2 at 105 C and 80% RH. The stability and durability of HT-PEM are studied with varied testing methods. After the continuous operation at open circuit voltage (OCV) for 500 h and continuous dry-wet circulation for 20000 cycles at 90 C, negligible change of OCV and hydrogen permeation current density are recorded, indicating good chemical and mechanical stability for HT-PEM. The improved property and performance originate from the new PFSA base material and improved morphology, in which the larger ioni... Read More

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Proton Exchange Membrane Fuel Cells (PEMFCs) serve as a clean and efficient way to utilize hydrogen energy, addressing resource scarcity and environmental pollution. This review discusses the advancements in the application of Polyhedral Oligomeric Silsesquioxanes (POSS) in fuel cell proton exchange membranes. The use of POSS has enhanced the mechanical properties and proton conductivity of membranes, significantly improving their overall performance. Key findings include the reduction of methanol crossover and increased thermal stability in Nafion membranes modified with POSS, which extends their operational temperature range. Additionally, modifications in PA-PBI membranes have notably decreased membrane swelling, thereby enhancing proton conductivity. When incorporated into other sulfonated aromatic polymer modifications, POSS also enhances the water retention capacity, therefore significantly increasing the proton conductivity of the composite membrane. These enhancements underscore the potential of POSS in advancing fuel cell performance, contributing to the development of clea... Read More

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Fuel cells are attracting attention as one of the key energy devices for achieving carbon neutrality in 2050. Currently, fuel cells are being improved for versatile mobile applications. Among the components of fuel cell devices, polymer electrolyte membranes for proton exchange, in particular, are required to have high proton conductivity at high temperature, high and low humidification, and thin membranes. Proton-exchange fuel cells utilize perfluorosulfonic acid (PFSA) ionomers and membranes from Chemours and 3M and Solvay [1]. Nafion membranes with a thickness of 178-25 m and Gore select membranes (with reinforcement) with a thickness of 20-5 m have been commercialized [2,3]. On the other hand, thinner polymer electrolyte membranes can reduce the ohmic voltage drop in fuel cells to improve performance and lower costs. However, it is difficult to obtain thin membranes of less than 20 m without reinforcement using PFSA ionomers. In this report, a thin PFSA electrolyte membrane (10 m) without reinforcement was successfully developed by introducing a PFSA-vinilon composite layer a... Read More

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Proton exchange membrane fuel cells (PEMFCs) have emerged as a promising technology for clean energy conversion with various potential applications. Due to its cost-effectiveness, sulfonated hydrocarbon has been researched as an alternative to Nafion, a commercial proton exchange membrane. However, sulfonated hydrocarbon's mechanical and chemical stability remains a critical challenge that needs to be addressed, as the membrane must withstand harsh operating conditions, such as wet-dry mechanisms in high-temperature operations. To compete with perfluorosulfonic acid (PFSA), sulfonated hydrocarbon should be reinforced with a polytetrafluoroethylene (PTFE) substrate. However, there are significant issues with incompatibility between sulfonated hydrocarbon and PTFE substrate. To improve the impregnation, simple and reproducible chemical treatment has been developed to enhance the hydrophilicity of PTFE using a mixture of acids and oxidizing agents. Moreover, surfactant was added to increase compatibility and improve impregnation. After the reinforced membrane was fabricated, the membran... Read More

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Fuel cells have attracted immense attention due to their application in green energy initiatives. The proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) are the two classes of fuel cells that work with polymer membrane technology. The pristine membranes of different polymeric materials lack the necessary properties to be called high-performing proton exchange membranes. However, the addition of porous materials like metal organic frameworks (MOFs) has brought substantial improvements regarding their proton conductivity, chemical, mechanical, and thermal steadiness. There have also been significant improvements in terms of methanol permeability. Metal-organic frameworks (MOFs) have fascinated scientists due to their porous structure, capacity to hold molecules, high selectivity, tunable pore size, and ability to undergo modifications in functionalization or post-synthetic modifications. Researchers have focused on developing composite membranes as proton exchange membranes (PEMs) for fuel cells (FCs). MOF-incorporated composite membranes have exhibited... Read More

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Owing to their facile hydrothermal management and high carbon monoxide tolerance, high temperature proton exchange membrane fuel cells (HT-PEMFCs) exhibit promising potential for various applications.In particular, high temperature proton exchange membranes (HTPEMs), as the core components of HT-PEMFCs, determine the performance of HT-PEMFCs.This paper primarily focuses on methods for improving the solubility and proton conductivity of HTPEMs.To address the current challenges encountered by HT-PEMFCs, various methods, including main chain structure design, co-blending, grafting, cross-linking, composite doping, and modifications of membrane morphology, are summarized.

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Within the past years, proton exchange membrane (PEM) fuel cells have become more and more attractive due to their potential for the transition towards an environmentally friendly hydrogen economy. Especially by reducing the platinum catalyst loading, significant system cost reductions could be achieved, but low Pt loadings still lead to unassigned voltage losses during operation. [1,2] In order to overcome those losses, well-designed catalyst layers with optimized ionomer content and distribution are indispensable. The used perfluorosulfonic acid (PFSA) ionomers for PEM fuel cells are commonly characterized by the chemical structure of the ionomer and the equivalent weight (EW), which strongly affects the proton conductivity. [3,4] Current research focusses on the synthesis of modified ionomers with higher oxygen permeability to reduce mass transport losses, but also investigates the influence of the ionomers molecular weight (MW). [1,5,6] A high MW minimizes the water uptake of the ionomer/membrane in liquid water, which is desired for the use in PEM fuel cells to reduce mechanica... Read More

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Increasing interest in hydrogen-powered fuel cells for electric energy generation led to the identification of serious limitations of state-of-the-art technologies. In particular, low-temperature fuel cell with a proton-exchange membrane (LT-PEM FC), which is widely considered as an optimal type for mobility, is reaching its technological limits. This is due to its operating temperature up to 90 C, defined by properties of perfluorinated, sulfonated membranes used as PEM, requiring liquid water for ensuring their ionic conductivity. In the case of heavy duty applications, high-power LT-PEMFC stacks suffer from local overheating, which is currently solved by intensive cooling. Ineffective heat-exchange and necessity of water regime control lead to limitations in total energy utilization. Such problem can be solved by increasing operating temperature up to 180 C, which is suitable for heat cogeneration. This requires application of appropriate PEM conducting even at an elevated temperature. Current state-of-the-art high-temperature PEM fuel cells (HT-PEM FCs) utilize PEMs based on po... Read More

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In the 21st century, proton exchange membrane fuel cells (PEMFCs) represent a promising source of power generation due to their high efficiency compared with coal combustion engines and eco-friendly design. Proton exchange membranes (PEMs), being the critical component of PEMFCs, determine their overall performance. Perfluorosulfonic acid (PFSA) based Nafion and nonfluorinated-based polybenzimidazole (PBI) membranes are commonly used for low- and high-temperature PEMFCs, respectively. However, these membranes have some drawbacks such as high cost, fuel crossover, and reduction in proton conductivity at high temperatures for commercialization. Here, we report the requirements of functional properties of PEMs for PEMFCs, the proton conduction mechanism, and the challenges which hinder their commercial adaptation. Recent research efforts have been focused on the modifications of PEMs by composite materials to overcome their drawbacks such as stability and proton conductivity. We discuss some current developments in membranes for PEMFCs with special emphasis on hybrid membranes based on ... Read More

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Proton exchange membrane fuel cells are devices that directly convert chemical energy to electricity. A hydrogen oxidation reaction takes place on the anode side, generating protons and electrons. In the cathode, oxygen reduction reaction involving oxygen, proton and electron occurs, producing water and heat. The water content in PEMFCs should be maintained at a reasonable amount to avoid water flooding or membrane dehydration. The thermal management and water management of PEMFCs are important for an efficient and stable operation of PEMFCs. Inside the multiscale spaces of PEMFCs, multiphase flow with a phase change, heat and mass transfer, proton and electron conduction, and electrochemical reaction simultaneously take place, which play important roles in the performance, lifetime and cost of PEMFCs. These processes should be well understood for better designing PEMFCs and improving the thermal management and water management.

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Abstract In the proton exchange membrane fuel cell, proton exchange membrane (PEM) serves as both the main conductor of protons and the fuelblocking membrane. Thus, high proton conductivity and excellent stability are expected for PEMs at the same time. According to chemical structure, this review divides PEM into three groups. Recently, highperformance PEM has been made possible by controlling chemical structure, organicinorganic hybrid composite membranes, and nanofiber composite membranes. One of them, nanofiber composite membranes, is distinguished by longrange order and is capable of achieving both strong proton conductivity with exceptional stability. The highperformance PEM has been accomplished by the presence of an acidrich layer, acidbase interaction, and proton transport channel in PEMs are also summarized in this paper. We believe that our discussion will help the researcher create highperformance PEM and pave the way for further developments in the field of energy materials as a whole.

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With the rise of sustainable energy, proton exchange membrane fuel cells (PEMFCs) have gained great advancements. To improve the power density and service life of fuel cells, each component of PEMFCs needs to be optimized. Each section introduces one main component and its development tendency. Current mainstream catalyst is platinum (Pt)-based materials, and metal-free catalysts and metal-nitrogen-carbon catalysts are promising candidates. Proton exchange membranes can be divided into perfluorosulfonic acid-based and non-fluorinated polymer-based membrane in low-temperature fuel cells. In the meanwhile, polybenzimidazole (PBI)-based membranes are promising material for high-temperature applications. The aforementioned materials will be systematically analyzed in this chapter. Perspectives on gas diffusion layer, bipolar plate, current collector, and sealing materials will also be discussed.

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Fuel cell holds the promise of being environmentally friendly and becomes one of the alternatives for renewable energy. Solid acids have superprotonic behavior which allows them to become conductors. It can function at high temperatures. Hydration, on the other hand, may be used to improve the performance of the solid acid. Moreover, the conductivity, stability, and crystal structure of the solid acid compounds of the fuel cell are all influenced by the size of the electrolyte membrane. Very few works have been done on solid acid fuel cells which are still under investigation to make it one viable as well as a reliable alternative to clean, renewable energy. In general, this work will provide an overview of the variables or characteristics that affect the technical effectiveness and performance of the unique superprotonic conductors for solid acid fuel cells.

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Proton exchange membrane fuel cells (PEMFCs) have caught the attention due to many of the extraordinary features that they possessed such as fast start-up, low operational temperature, large energy conversion rate, and environmental friendliness over other types of fuel cells. For PEMFCs, usually, a hydrated proton exchange membrane acts as an electrolyte and protons (H + ) are used as mobile ions. For better efficiency of the proton transport, proton conductivity value of the electrolyte must lie in the range of 0.02 S cm 1 or higher. Metal-organic frameworks (MOFs) are the porous hybrids of organic-inorganic materials and have emerged as the promising proton conducting materials because of many advantages like large surface area, controllable cavity structure, tenability, modifiable functional groups, and good stability. This books chapter will throw light on different types of MOFs employed to function as PEMFCs.

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Over the past several years, proton exchange membrane fuel cells (PEMFCs) have become popular as one of the most crucial energy sources amongst the various fuel cells (FCs) in view of energy and environmental sustainability. Proton exchange membranes (PEMs) are the main component of PEMFCs; primarily, fluoromembrane polymer was used as membrane material in PEMFCs. It has a good ionic conductivity, low permeability, mechanical stability, low costs, long service life, thermal stability, and easy construction of membrane electrode. In contrast to other FCs, the assembly and handling of PEMFCs is less complex compared to other FCs and operates at low temperature (60C80C). Membrane materials are used in the FC system: fluorinated ionomers, perfluorinated ionomers, nonfluorinated ionomers, sulfonated poly(arylenes), and an acid-base complex. Perfluorosulfonic acid (PFSA) and poly(arylene ethers) with fluorinated and sulfonated polymers have high H + conductivity and good physicochemical characteristics, which make polymers a good PEM in PEMFCs. This chapter focuses on research in PEM ma... Read More

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Proton exchange membrane fuel cells are devices that directly convert the chemical energy of a chemical reaction into electrical energy in the form of direct current. This device has characteristics that position itself as a promising source of clean energy. An essential component that directly affects the performance of fuel cells is the membrane used as electrolyte. In order to improve its efficiency, the membrane should be designed to comply with specific requirements such as high proton transport, good electrical insulation, low fuel permeability, and excellent thermal and chemical stability, to name only the most relevant elements. One of the most widely used and researched materials is the Nafion membrane, a hydrophobic fluoropolymer that contains hydrophilic side chains or ramifications ended in sulfonic acid group (SO 3 H). Throughout this chapter, the properties of Nafion and specifically its relevant structural and transport models were analyzed in detail. In this sense, small-angle X-ray/neutron spectroscopy (SAXS-SANS) are mandatory supplements and powerful tools for cha... Read More

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The need for energy for the growing population and consuming fossil fuels has made clean energy more popular. One way to generate clean energy is to use fuel cells. The basis of energy production in these systems is based on an electrochemical reaction. In this chapter, fuel cells and their history are described, and then, the applications and energy production mechanisms are expressed. The principal part of this chapter is to get acquainted with the materials used in the proton exchange membranes of the fuel cell and the ways of characterizing these membranes. Various materials have been used for PEM, most of which are sulfonic acidbased membranes. Different methods of PEM preparation have led to varying classifications of these materials, which can be referred to direct polymerization, post-sulfonation, and chemical and radiation grafting methods.

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In this review, a comparative analysis of the literature and our own results obtained in the study of the physicochemical, dielectric, and proton-conducting properties of composite polymer materials based on 1H-1,2,4-triazole has been carried out. It has been established that 1H-1,2,4-triazole and homopolymers and copolymers of 1-vinyl-1,2,4-triazole are promising for the development of proton-conducting fuel cell membranes. They significantly improve the basic characteristics of electrolyte membranes, increase their film-forming ability, increase thermal stability up to 300330 C, increase the electrochemical stability region up to 34 V, promote high mechanical strength and morphological stability of membranes, and provide high ionic conductivity (up to 103101 S/cm) under anhydrous conditions at temperatures above 100 C. There is also an improvement in the solubility and a decrease in the glass transition temperature of polymers based on 1-vinyl-1,2,4-triazole, which facilitates the processing and formation of membrane films. The results obtained demonstrate the uniqueness of ... Read More

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With the development of renewable energy, proton exchange membrane fuel cells (PEMFCs) are considered as a promising candidate of next-generation energy conversion.While the design of proton exchange membranes (PEMs) have been considerably investigated over the last decades, the performance and durability are still issues in PEMFCs.We have synthesized a series of sulfonated poly(arylene perfluoroalkylene)s with welldeveloped morphology, high proton conductivity, good fuel cell performance and excellent oxidative stability.The relationship among the chemical structures, bulk membrane properties and fuel cell performance is discussed and reviewed.The properties of those membranes are compared with the-state-of-the-art PEM (perfluorosulfonic acid).

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Abstract Fuel cells offer great promise for portable electricity generation, but their use is currently limited by their low durability, excessive operating temperatures, and expensive precious metal electrodes. It is therefore essential to develop fuel cell systems that can perform effectively using more robust electrolyte materials, at reasonable temperatures, with lowercost electrodes. Recently, proton exchange membrane fuel cells have attracted attention due to their generally favorable chemical stability and quick startup times. However, in most membrane materials, water is required for proton conduction, severely limiting operational temperatures. Here, for the first time it is demonstrated that when acidified, PAF1 can conduct protons at high temperatures, via a unique framework diffusion mechanism. It shows that this acidified PAF1 material can be pressed into pellets with high proton conduction properties even at high temperatures and pellet thickness, highlighting the processibility, and ease of use of this material. Furthermore, a fuel cell is shown with high power den... Read More

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Abstract Background The wellaligned proton exchange membrane (PEM) developed through magnetic field treatment has had a significant impact on the chemistry community related to fuel cell technologies. This is because it possesses advanced proton transport properties that can be efficiently utilized in energy storage devices. The aligned membrane boasts exceptional proton conductivity and power density, particularly in hydrogenoxygen fuel cell applications, due to its short proton conduction path, low dependency on humidity, and high barrier to gas permeability. These characteristics can enhance the performance of the aligned PEM. Methods This review outlines various methods for fabricating aligned membranes using a magnetic field. It summarizes the previous and current research and development aimed at improving the properties of the aligned PEM for fuel cell applications. Significant Findings Several research gaps and challenges in enhancing the performance of magnetic fieldaligned PEM have been identified in this review, suggesting promising avenues for future research.

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Proton exchange membrane unitized regenerative fuel cell (PEM-URFC) is a promising energy storage and conversion device for large-scale and long-term applications. Previous research has primarily focused on materials development studies, with performance and durability not evaluated at relevant conditions. Such an approach becomes insufficient for making URFC technology commercially competitive. In this review, we highlight recent progress on high-performing PEM-URFCs, focusing on electrode engineering, key components and operating approaches that take realistic operating conditions into consideration. Key components of a membrane electrode assembly (MEA), including catalyst layer, diffusion media, and membrane, which require different optimization strategies, are discussed in this review.

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Abstract Although proton exchange membranes (PEMs) are widely deployed in an array of commercial applications, limitations linked to their proton conductivity, water retention, and gas permeability still limit ultimate device performance. While ex situ studies have shown additives can enhance membrane stability and mass transport, to date few have demonstrated that these performance enhancements are maintained when tested in commercially relevant electrochemical technologies, such as fuel cells or electrolyzers. Herein, a new multifunctional additive, 2D poly(triazine imide) (PTI), is demonstrated for composite PEMs, which is shown to boost proton conductivity by 37% under optimal high relative humidity (RH) conditions and 67% at low RHs. PTI also enables major improvements (over 55%) in both current and power densities in industrially relevant PEM fuel cells (PEMFCs). Most importantly, in situ and ex situ characterization suggests that the enhanced performance is due to polymer aggregatePTI clusters that form with increasing 2D character and improved longrange connectivity, while ... Read More

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Abstract Due to the increasing global demand for sustainable energy sources, fuel cells are being considered as a green alternative to conventional power generation methods. Proton Exchange Membrane Fuel Cells (PEMFCs) are particularly promising energy sources due to their high energy efficiency and low environmental impact. However, there is an urgent need to develop proton-conducting materials that can operate under low-humidity conditions and at high working temperatures. In this study, new proton conducting membranes were prepared using poly-2,2'-(m-phenylene)-5,5'-bibenzimidazole (PBI) and varying amounts of a protic ionic liquid, methylimidazolium triflate [MeIm/TfO], through a solution casting method. The thermal properties and conductivity of these membranes were investigated. The obtained parameters indicate that PBI membranes doped with either MeIm/TfO or BuIm/TfO, which were previously studied by our group, are of definite interest for further investigation as potential electrolytes for PEMFCs.

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For high-temperature proton exchange membrane fuel cells (HT-PEMFCs), the PA amount in membrane electrode assembly (MEA), which can be tuned by the membrane and binder materials, has a vital influence on cell performance. Herein, to control the PA uptake ability of the MEA, a series of membrane and binder materials functionalized by nitrogen heterocyclic groups with different acidophilic properties were synthesized via superacid-catalyzed copolymerization of p-terphenyl and functional aldehydes. As expected, the PA-doped TP-2-IM membrane exhibits the highest proton conductivity of 66 mS/cm due to the largest PA uptake, and the corresponding MEA using TP-2-IM membrane displays the highest PPD of 621 mW/cm2 at 160 C. However, the MEA using TP-2-IM as binder demonstrates the poorest cell performance mainly attributed to the limited mass transport resulted from the too strong PA interplay. Notably, owing to the suitable PA uptake ability of TP-4-IM binder, a good balance between the proton conductivity and fuel diffusion in the MEA has been achieved. Thus, the corresponding MEA illustra... Read More

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Due to emergence of clean, green and digital electric mobility, there is huge demand of electro-chemical devices such as battery driven electric vehicle or/and proton exchange membrane (PEM) fuel cell driven electric vehicles. Unfortunately, due to high cost, declined electro-chemical performance and poor durability, the global commercialization of electro-chemical conversion and storage devices is being hampered. PEM fuel cell driven electric vehicle has several advantages over battery driven electric vehicle such as cost, efficiency, operability and most importantly energy densities. However, the durability of components of PEM fuel cell such as membrane, electro-catalyst and bipolar plates is on of major challenges in PEM fuel cell. Therefore, understanding the degradation behavior and its mechanism in advanced functional materials such as proton conducting membrane followed by its mitigation is a crucial step to enhance the stability of PEM fuel cells. The detailed investigations were carried out to identify the electro-chemical, physical and process parameters causing membrane d... Read More

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Proton conductivity and acid retention property of PBI-based polymer electrolyte membrane is critical factor for high-temperature PEMFCs with high performance. The present study was undertaken in order to demonstrate the effect of SnP2O7 microparticles incorporation for the PBI-based membrane to the fuel cell performance. Besides, the correlation between dispersion property of additives and fuel cell performance was investigated, by taking the larger particle sizes of Sn-originated material into account. Highly dispersed SnP2O7 microparticles derived by the wet mechanochemical treatment has resulted in the novel PBI-based composite membrane with high-proton conductivity (4.17 mS cm1 at 160 C, anhydrous) and superior acid retention property. Consequently, the highest peak power density of 373 mW cm2 at 160 C under anhydrous conditions was achieved for the composite membrane with wet-mechanical milled SnP2O7, while the membrane without mechanochemical treatment showed lowest peak power density (168 mW cm2) even inferior to the pure PBI membrane. Investigations into the PBI-based c... Read More

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The study of proton exchange membrane fuel cells (PEMFCs) has received great attention from the scientific community. The main objectives of research in this area are to reduce greenhouse gas emissions, especially in the automotive industry, and develop new techniques and materials to increase the efficiency of PEMFCs at a reasonable cost. In this regard, the development of high-performance polymeric membranes is presented together with nanomaterials with high catalytic activity and stability that work at low and moderate temperatures. Similarly, the development of new techniques or materials for electrodes and catalysts that allow the development of new improved water management techniques within PEMFCs is studied. This chapter examines recent advances and future trends in the modeling of PEMFCs and their components. In addition, it discusses the main applications of PEMFCs and presents current and projected statistical data.

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Hydrogen fuel cell (FC) technologies are being worked on as a possible replacement for fossil fuels because they produce a lot of energy and do not pollute the air. In FC, ion-exchange membranes (IEMs) are the vital components for ion transport between two porous electrodes. However, the high production cost of commercialized membranes limits their benefits. Various research has focused on cellulose-based membranes such as IEM with high proton conductivity, and mechanical, chemical, and thermal stabilities to replace the high cost of synthetic polymer materials. In this review, we focus on and explain the recent progress (from 2018 to 2022) of cellulose-containing hybrid membranes as cation exchange membranes (CEM) and anion exchange membranes (AEM) for proton exchange membrane fuel cells (PEMFC) and alkaline fuel cells (AFC). In this account, we focused primarily on the effect of cellulose materials in various membranes on the functional properties of various polymer membranes. The development of hybrid membranes with cellulose for PEMFC and AFC has been classified based on the comb... Read More

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As the large-scale commercialization of proton exchange membrane fuel cells (PEMFC) for numerous applications, including heavy-duty trucks draws nearer, there is increasing interest in optimizing fuel cell membranes for both improved efficiency and durability. One of the major membrane attributes being considered for optimization is thickness. The current range of (perfluorosulfonic acid) PFSA membrane thicknesses employed for commercial applications range from 8 -25 m. As with most adjustable materials parameters, there are a host of properties (cost, gas permeability, proton conductivity, etc.) that require co-optimization to provide the overall preferred position. For example, thin membranes will minimize proton resistance, facilitating high power densities, but will simultaneously allow increased gas crossover fluxes that can contribute to both reduced fuel efficiency and increased oxidative stress. On the other end of the spectrum, thick membranes will decrease gas crossover fluxes, offering improved fuel efficiency while simultaneously decreasing power density. A major questio... Read More

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Electrochemical energy conversion devices such as fuel cells are crucial for the development of renewable, sustainable alternative energy vectors. The implementation of fuel cell technology is of particular interest in portable, transportation, and stationary energy conversion sectors. There are challenges that still impede fuel cell commercialization at scale: cost, performance, and durability of the membrane-electrode-assemblies (MEA)s that comprise fuel cell stacks. MEAs typically consist of catalyst layers (CL) coated on either side of a proton-exchange membrane (PEM), and gas diffusion layers (GDL) which control water management and reactant gas mass transport. The CL provides a path for proton, electron, and gas transport to (and from) the Pt catalyst surface. Commonly, a perfluorosulfonic acid (PFSA) ionomer, e.g., Nafion is employed as both the proton exchange membrane (PEM) and ionomer. However, perfluorinated materials are not without challenges as their manufacture utilizes controlled substances and potentially environmentally hazardous chemical feedstocks, which add to t... Read More

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As society considers alternatives to energy systems based on fossil fuel combustion, high-temperature proton exchange membrane (HT-PEM) fuel cells may play an important role in our future energy and transportation portfolio. When compared to low-temperature proton exchange membrane (LT-PEM) fuel cells, HT-PEM technology offers enhanced electrode kinetics, simplified water management, and most notably increased tolerance to fuel impurities such as carbon monoxide. However, compared to more conventional LT-PEM systems, less is known about the durability, performance, and fabrication of HT-PEM materials. Comprised of multiple layers, the membrane electrode assembly (MEA) is a fuel cells central component. In a fabrication process similar to LT-PEM MEAs, the proton-conducting membrane, electrodes, gas diffusion layers and sub gaskets are usually hot-pressed together. The parameters surrounding the hot-pressing operation can have a significant impact on the ultimate performance of the fuel cell, in addition to influencing process reliability and repeatability. In the current research, me... Read More

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Abstract Fuel cells are expected to play an important role in global carbon neutralization and future social development with high conversion efficiency and zero emissions. The core of the fuel cell is the proton exchange membrane (PEM). However, the unclear of the proton transport mechanism in PEMs limits the development of membranes with improved performance. Perfluorosulfonic acid (PFSA) membranes are currently the most widely used type of PEM, and exhibit varying proton transport capabilities with various chemical structures. In this study, the hydration morphology of several PFSA membranes was studied using dissipative particle dynamics. The result shows that under low water content the hydrophilic and hydrophobic phases separated and the water clusters are relatively isolated. The increased water content formed hydrophilic channels, while the increase in equivalent weight decreases the water cluster size and improves water dispersion. Aciplex 1128 shows great variation owing to the presence of a long sulfonic acid terminated side chain in water cluster size and dispersion compa... Read More

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Abstract Fuel cells will play a critical role in a renewable energy powered society, whether in mobility or stationary applications. Certain challenges remain to be addressed if performance and cost dynamics of these systems is to achieve large scale, high unit number roll out. This review deals with polymer electrolyte membranebased fuel cells with a specific focus on membrane materials and their innovative fabrication based on chemical vapor deposition (CVD) approaches. These deposition techniques are introduced, as are the potential improvements relating to cell performance, namely proton conductivity and stability. The potential benefits of applying CVDbased synthesis in the fabrication of polymer electrolytes is also discussed with respect to future fuel cell development.

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Abstract The high-temperature proton exchange membrane fuel cell (HT-PEMFC) offers several advantages, such as high proton conductivity, high CO tolerance, good chemical/thermal stability, good mechanical properties, and low cost. The proton exchange membrane (PEM) is the critical component of HT-PEMFC. This work discusses the methods of current PEMs development for HT-PEMFC including modifications of Nafion membranes and the advancement in composite PEMs based on non-fluorinated polymers. The modified Nafion-based membranes can be used at temperatures up to 140 C. Nevertheless, the application of Nafion-based membranes is limited by their humidification with water molecules acting as proton carriers and, thus, by the operation conditions of membranes under a relative humidity below 20%. To obtain PEMs applied at higher temperatures under non-humidified conditions, phosphoric acid (PA) or ionic liquids (ILs) are used as proton carriers in PEMs based on non-fluorinated polymers. The research discussed in this work provides the approaches to improving the physicochemical properties... Read More

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Improving the power density ( 700 mW cm -2 ) and long-term durability of fuel cells are crucial for promoting the practical application of high-temperature proton exchange membrane fuel cells (HT-PEMFCs). In this study, a high-power density greater than 1000 mW cm -2 of fuel cell is obtained based on the designed polybenzimidazole (PBI) composite membranes containing cation-rich domains and stable two-phase interfaces. The designed membranes were fabricated by incorporating densely alkyl-bromide-functionalized polymer particles into the PBI membrane. The resulting composite membrane exhibited an improved mechanical strength of 12.6 MPa and high proton conductivity of 181.6 mS cm -1 at 160 o C. Under a Pt loading of 0.6 mg cm -2 and H 2 /O 2 , without any humidification and backpressure, the power density of the corresponding composite membrane-based fuel cell reached 1090.5 mW cm -2 at 160 o C, which is one of the most outstanding cell performances among all reported acid-doped high-temperature proton exchange membranes. Additionally, superior stability with a voltage decay rate of ... Read More

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Improving the power density ( 700 mW cm-2) and long-term durability of fuel cells are crucial for promoting the practical application of high-temperature proton exchange membrane fuel cells (HT-PEMFCs). In this study, a high-power density greater than 1000 mW cm-2 of fuel cell is obtained based on the designed polybenzimidazole (PBI) composite membranes containing cation-rich domains and stable two-phase interfaces. The newly designed membranes were fabricated by incorporating densely alkyl-bromide-functionalized polymer particles into the PBI membrane. The resulting composite membrane exhibited an improved mechanical strength of 12.6 MPa and high proton conductivity of 181.6 mS cm-1 at 160 oC. The power density of the corresponding composite membrane-based fuel cell reached 1090.5 mW cm-2 under a Pt loading of 0.6 mg cm-2 and H2/O2, without any humidification or backpressure at 160 oC, which is one of the most outstanding cell performances among all reported acid-doped high-temperature proton exchange membranes. Additionally, superior stability with a voltage decay rate of 0.0132 m... Read More

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Proton-exchange membrane fuel cells (PEMFC) are a potential technology for renewable energy sources. PEMFC operating at higher temperatures provides numerous advantages, including increased power density, durability, and the use of higher purity hydrogen fuel. In order to facilitate high temperature operations, research has been conducted on integrating ionic liquids into the proton exchange membrane. Ionic liquid membranes frequently have poor mechanical stability, rendering them unsuitable for use in fuel cells or resulting in poor fuel cell durability. Polyionic liquids (PILs) have enormous potential for both high and low temperature PEMFC applications. The Poly([HSO 3 -BVIm][TfO]-10 membrane performs well at low temperatures, with a proton conductivity of 0.2090.293 S/cm at 2540 C, which is greater than the most often used membrane Nafion. The OPBI/PVImBr (H)-g-SiNP-10% at 160 C. The OPBI/PVImBr (H)-g-SiNP-10% membrane performs well at 160 C, with proton conductivity of 0.25 S/cm at 170 C but a low mechanical strength of 2.76 MPa. The 6FPBIPIL10 membrane doped with phosph... Read More

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Proton exchange membrane (PEM) is an essential component of the membrane electrode assembly in the polymer electrolyte fuel cells (PEFC) which should display efficient proton conduction for better performance. Chitosan (CS) based PEMs are proposed as proton conductors for PEFCs for their film-forming and biodegradable nature to replace the synthetic, hydrocarbon-derived PEMs. However, the crystalline nature as well as poor reinforcement of the saccharide backbone lowers the proton conductivity of CS, and this prevents its commercialization as state-of-the-art PEM for fuel cell applications. Here, we report a CS based nanocomposite membranes which delivers a maximum proton conductivity of 44.45 mS cm1 at 80 C under partially hydrated conditions. Exfoliated MoS2 nanosheets and magnetically active NiOCo3O4 are introduced as active fillers in the CS matrix to improve the proton conductivity and stability of the prepared membranes. The fabricated CS nanocomposite membranes are also investigated for their mechanical characteristics, degree of swelling, water-retention and ion-exchange p... Read More

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