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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Research focusing on catalyst layers is critical for enhancing the performance and durability of proton exchange membrane fuel cells.

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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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Polymer electrolyte membrane fuel cells (PEMFC) are the dominant technology for hydrogen-powered fuel cell electric vehicles in clean transportation systems. To be suitable for commercialization and applicability in real-world use-cases, light and heavy-duty fuel cell vehicles require lifetimes of over 8,000 and 30,000 hours, respectively [1]. Hence, enhancing the durability of all fuel cell components, particularly the proton exchange membrane (PEM), is of great importance. Recently, fuel cell membranes based on hydrocarbon (HC) chemistries have become increasingly common in the literature [2]. Materials with polyaromatic backbones, tunable electrochemical properties, and low reactant permeability are increasingly seen as potential alternatives to incumbent perfluorosulfonic acid (PFSA) materials [2]. Additionally, as restrictions on the use of fluorinated materials in various industries continue to grow, the importance of HC chemistries will as well. Sulfo-phenylated polyphenylenes (sPPPs) are a particular class of HC materials that show promise [3]. However, the phase separation b... 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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