Search Results (392)

In this work, a dynamic polymer electrolyte membrane (PEM) fuel cell system is modelled in Modelica using the in-house developed, open-source library ThermoFluidStream. The focus lies on the fuel cell stack, the hydrogen fuel supply and the air supply. Additionally, the thermal management and the power electronics are considered in a simplified manner. Dynamic simulations are carried out for this system over an exemplary aircraft gate-to-gate mission. Simultaneously, a baseline control scheme is developed to provide the fuel cell with sufficient product gases in a suitable state regarding the temperature, pressure and relative humidity. The results indicate that the fuel cell system performs well with standard PI controllers. Only when strong dynamics occur, such as when going from taxi to take-off, does the control scheme show some weaknesses, as expected. This fuel cell system together with its control is a powerful baseline for future investigations. Full article

Decarbonizing air travel poses a major technological challenge, driven by the substantial power requirements of the drivetrain and the demanding weight and volume constraints of airborne systems. One promising avenue involves leveraging the high specific energy of hydrogen by designing compact, high-power fuel cell stacks to supply power for electric drivetrains. However, a key drawback of such propulsion architectures is the substantial heat generated within the fuel cells, which necessitates bulky and heavy thermal management systems to ensure safe and continuous operation. This study investigates a proposed air-based thermal management system, which operates by introducing pulsating heat pipes into the bipolar plates of a High-Temperature Polymer Electrolyte Membrane Fuel Cell (HT-PEM FC) stack. If proven to be feasible, heat pipe assisted air cooling may provide the benefit of reducing overall system complexity by decreasing the number of components in the thermal management system. To evaluate the thermal performance of the proposed system, a one-dimensional thermal model was initially developed in a previous study to describe the temperature distribution along the length of a heat pipe. Building upon this foundation, the present work extends the model by incorporating a two-dimensional Computational Fluid Dynamic (CFD) analysis to account for geometry-specific effects within the hexagonal design. Results indicate that the heat transfer from the hexagonal heat pipe geometry to the coolant air flow was marginally overestimated in previous analytical calculations. Revised heat transfer rates led to a shift in the predicted temperature distributions, resulting in the need for either increased external airflow, extended condenser sections, or reduced inlet temperatures to maintain target operating conditions. Although these adjustments may result in a slight increase in system mass and parasitic power consumption, the overall impact is limited, and the heat pipe-assisted air cooling approach remains theoretically feasible. Based on the results, design modifications are proposed and their impact on thermal performance is evaluated to address the challenges of heat rejection and temperature uniformity. A modification based on variation and optimization of PHP meander lengths was evaluated using the updated model and it significantly improved temperature homogeneity across the evaporator. Full article

Low-temperature polymer electrolyte membrane fuel cell systems can achieve higher efficiency than diesel engines, but heat rejection remains a major challenge in class-8 heavy-duty fuel cell trucks. For the same rated power, the radiator heat load is greater than that in a diesel engine, while the allowable operating temperatures are lower. This work proposes and evaluates 400 kW_e fuel cell–battery hybrid (FCH) platforms and operating strategies that manage heat rejection without enlarging the radiator frontal area. Three FCH platforms are identified, each varying in fuel cell system (FCS) rated power, battery energy storage system (ESS) capacity, and maximum stack coolant exit temperature ($T_{h1}$). All three satisfy key system and vehicle requirements, including 175 kW_e FCS power at top sustained speed, 400 kW_e FCH power on a 6% grade climb, a target stack power density (PD) of 750 mW_e/cm², and heat rejection constraints. The first FCH has the smallest FCS, the largest ESS, and a $T_{h1}$ of 90 °C. The second achieves the highest PD of 840 mW_e/cm² at a $T_{h1}$ of 95 °C. The third has the largest FCS, the smallest ESS, and a $T_{h1}$ of 102 °C. At a $T_{h1}$ of 115 °C, the platform can be configured as a stand-alone 400 kW_e(net) FCS without hybridization, but the achievable PD drops to 460 mW_e/cm². Full article

This review summarizes the current state of research on perfluorinated sulfonic acid (PFSA) ionomers, including both classic Nafion and a wide range of alternative chemical modifications, as well as new-generation composite and stabilized membranes. The accumulation of a large body of experimental and modeling data in recent years highlights the need to rethink the differences between traditional ionomers and their modern counterparts, which is especially relevant in light of the development of new materials and their expanding applications. PFSA ionomers have a rich research history, playing a key role in the development of polymer-electrolyte fuel cell technologies and other electrochemical systems. At the same time, these materials have become a unique interdisciplinary platform, stimulating the development of new methods of characterization, modeling, and analysis. In PFSA research, technological progress is closely intertwined with fundamental science, encompassing electrochemistry, polymer physics, mechanics, chemistry, and multiscale modeling. The data we collected allowed us to identify new structural and functional patterns, analyze the behavior of ionomers in various states—from thin films and interfaces to bulk membranes—and summarize numerous previously fragmented relationships. Full article

Hydrogen fuel-cell-powered all-electric aircraft are promising for decarbonizing short-range aviation, but the substantial low-temperature waste heat demands a compact thermal management system (TMS). This study presents a methodological framework for the integrated co-design of the TMS and powertrain using multi-objective optimization and holistic mission-level analysis to identify optimal TMS designs and operating strategies. Changes in TMS net drag translate into changes in required aircraft thrust, while changes in powertrain, TMS, and fuel mass affect the available payload under a constant maximum take-off mass assumption. This iterative process yields performance metrics across TMS cooling architectures (parallel or series), heat exchanger mass-drag characteristics, coolant temperature targets (50, 70, or 90 °C), and installation objectives (minimizing mass or ram-air duct length). The optimal design is a parallel cooling architecture that balances mass-specific heat rejection of 4.77 kW kg⁻¹ at hot-day take-off with drag-specific heat rejection of 1.29 kW N⁻¹ at standard-day cruise. A reduction in coolant temperature at standard-day missions entails no significant performance penalties and could improve the efficiency of electrical components. A shorter ram-air duct significantly decreases the available payload by 630 kg but may facilitate nacelle integration. The findings underscore that holistic TMS-powertrain co-design and optimization is essential for rigorous design of sustainable all-electric aircraft. Full article

Multi-stack Polymer electrolyte Membrane Fuel Cell (PEMFC) systems are increasingly adopted in heavy-duty mobility to overcome the power limitations and thermal instability of single-stack configurations. However, the overall energy efficiency, hydrogen utilization, and thermal behavior of multi-stack fuel cell trucks are highly dependent on the applied Power Management System (PMS). In this study, high-fidelity, system-level dynamic model of multi-stack fuel cell truck was developed using Matlab/Simscape^TM, and three PMS approaches (rule-based control, state-machine control, and fuzzy logic control) were comparatively evaluated. The analysis includes coolant temperature regulation, hydrogen consumption, battery State of Charge (SoC) dynamics, and the parasitic power demand of Balance of Plant (BoP) components. Results show that the fuzzy logic PMS provides the most balanced operating profile by smoothing transient fuel cell loading and actively leveraging the battery during high-demand periods. In the thermal domain, the fuzzy logic PMS reduced temperature overshoot by up to 61.20%, demonstrating the most stable thermal control among the three strategies. Hydrogen consumption decreased by 3.08% and 0.89% compared with the rule-based and state-machine PMS, respectively, while parasitic power consumption decreased by 7.12% and 3.32%, confirming improvements in overall energy efficiency. TOPSIS-based multi-criteria decision analysis further showed that the fuzzy logic PMS achieved the highest closeness coefficient (0.9112), indicating superior system-level performance. These findings highlight the importance of PMS design for achieving energy-optimal and thermally stable operation of multi-stack PEMFC trucks and provide practical guidance for future control strategies, heavy-duty mobility applications, and next-generation hydrogen powertrain optimization. Full article

This article reports on how the length of the alkyl chain influences the morphological properties of thiol-stabilized silver nanoparticles (Ag NPs) and their subsequent effects on the performance and durability of proton exchange membrane fuel cells (PEMFCs). We synthesized thiol-stabilized Ag NPs by varying the alkyl chain length: 1-hexane thiol (C6), 1-octanethiol (C8), 1-decanethiol (C10), 1-dodecanethiol (C12), and 1-tetradecanethiol (C14), which we achieved using the two–phase Brust–Schiffrin method. X-ray Diffraction (XRD) patterns confirm the formation of crystalline Ag NPs. A morphological study conducted using a Transmission Electron Microscope (TEM) demonstrated that smaller alkyl chain length thiols (C6, C8, and C10) tend to coalesce, while C12 shows better uniformity with no agglomeration. C14 produces larger nanoparticles. A distinct pressure-area isotherm was observed when Ag NPs were spread at the water/air interface of a Langmuir–Blodgett (LB) trough. After obtaining the monolayer formation pressure range, we coated the Nafion 117 membrane of a polymer electrolyte membrane fuel cell with these nanoparticles to form monolayers of different Ag NPs (C6, C8, C12, C14) at various surface pressures (2 mN/m, 6 mN/m and 10 mN/m). Maximum power output enhancement was observed for C12, while other nanoparticles (C6, C8, C10, C14) did not exhibit noticeable power enhancement for PEMFCs. C12 Ag NPs deposited at surface pressure 6 mN/m give maximum power density increase (26.5%) at the fuel cell test station. In addition, we examined the carbon monoxide (CO) resistance test by mixing 0.1% CO with hydrogen (H2), and C12 Ag NPs showed the highest resistance to CO poisoning. However, no enhancement in power or CO tolerance was observed when C12 Ag NPs were coated by spray coating. These outcomes showcase that alkyl chain length plays a critical role in controlling the size and distribution of thiol-stabilized nanoparticles, which eventually has a direct impact on the performance and CO resistance of PEMFCs when applied to polymer electrolyte (Nafion 117). In addition, surface pressure during monolayer formation controls the distribution of Ag NPs (the distance between nanoparticles at the membrane interface), which is necessary to achieve catalytic activity for power improvement and to prevent platinum (Pt) poisoning by CO oxidation at ambient conditions. Full article

Membrane electrolytes play a critical role in energy conversion devices. The development of stable, efficient membrane electrolytes is urgent and demands paramount attention for the successful commercialization of fuel cells. Chitosan, a naturally occurring material, and silica particles were used as precursors for organic–inorganic membrane polymers. The silica nanoparticles were prepared by the sol–gel and Stober methods and characterized using various techniques, including XRD, FTIR, etc. The silica-incorporated membranes show improved properties, with the sulfur-functionalized membranes having optimal proton conductivity, ion-exchange capacity, and tensile strength of 0.0238 S/cm, 2.86 meq/g, and 7.3 MPa, respectively. It also showed the lowest methanol permeability. This was clear proof that membrane functionalization has a positive impact on tuning the properties of electrolyte membranes and should be further explored in membrane development. Full article

Hybrid membranes are promising alternatives for various applications, combining a continuous polymer phase with a dispersed filler phase to achieve synergistic functional benefits. The ideal fillers should possess well-defined structures and unique properties for multi-functionality, as well as being sourced from renewable, biodegradable materials for sustainability purposes. This study explored the potential of using cellulose-based renewable materials as fillers for hybrid polymer electrolyte membranes (PEMs) in fuel cells. Cellulose whiskers (CWs), known for their high crystallinity and elastic modulus, were effectively synthesized via optimized sequential alkali treatment and acid hydrolysis. Subsequent functionalization with citric acid was performed to enhance their reinforcing properties and overall performance. Initial characterization using ATR-FTIR and XRD confirmed the CWs’ structural composition, high crystallinity, and the presence of reactive groups (sulfate and hydroxyl). The functionalization process introduced new carbonyl groups (C=O), which was verified by ATR-FTIR, while maintaining high hydrophilicity. Morphological analysis revealed that the crosslinked CWs created a denser and more compact microstructure within the membrane, leading to a significant enhancement in mechanical strength. The modifications to the cellulose whiskers not only improved structural integrity but also boosted the membrane’s ion exchange capacity (IEC) and proton conductivity compared to membranes with unmodified CWs. Initial experiments demonstrated CWs’ compatibility as a filler in a polysulfone (PSU) matrix, forming hybrid membranes suitable for fuel cell applications. Full article

Polymer Electrolyte Membrane and Direct Methanol Fuel Cells (PEMFCs/DMFCs) are vital clean energy technologies, yet their adoption is hindered by limitations in industry-standard PFSA membranes. PFSA degrades above 80 °C, suffers substantial methanol crossover, and contains environmentally persistent PFAS, which raises significant environmental and cost concerns due to its persistence and bioaccumulation, driving a global imperative for sustainable, fluorine-free alternatives. In response to these challenges, the PCAM Lab has dedicated extensive research efforts to developing advanced PEMs. A primary focus is non-fluorinated alternatives (NFPs), including sulfonated Polysulfone (sPSU) and Sulfonated polyether ether ketone (sPEEK), which have emerged as a compelling, cost-effective, and environmentally friendly alternative to the PFSA benchmark. Beyond NFPs’ intrinsic advantages, the lab’s implementation of nanocomposite strategies, involving the incorporation of various functional nanofillers, has proven transformative. This report provides a comprehensive, critical analysis of the state of the art in PEM research, contextualizing the specific contributions of the Physical Chemistry Applied Materials (PCAM) Lab within the broader global scientific dialog. While the PCAM Lab has made notable strides in utilizing Sulfonated Polysulfone (sPSU) and nanocomposite strategies, a true assessment of the field requires integrating these findings with the seminal works of leading international research groups. By synthesizing data on sulfonated polyphenylenes, advanced graphene architectures, and industrial manufacturing constraints, this analysis illuminates the divergent pathways currently being explored to overcome the “Nafion Dilemma”. Full article

The lifetime of polymer electrolyte membrane fuel cells (PEMFCs) is significantly influenced by the degradation of their catalysts. A composite-type electrocatalyst support with the formula Ti_(1−x)Mo_xO₂-C (x: 0–0.2, C: carbon) has been found to provide higher stability for the Pt active metal than carbon alone. Non-traditional carbon materials such as graphene nanoplatelets (GNPs) and graphite oxide (GO) offer new possibilities for supports. This work aims to explore whether it is possible to combine the advantageous properties of GNP and GO in composite-supported Pt electrocatalysts. Composites prepared using the modified sol–gel method and Pt catalysts supported on them were characterized by physicochemical methods. Electrochemical behavior in terms of CO tolerance, activity and stability was studied. Although GO transformed into a mainly graphitic material during composite synthesis, its addition still increased the functional group content of the carbonaceous backbone. The electrical conductivity was significantly higher when GNPs-GO mixtures were used as the starting carbon material compared to the use of pure GNPs. Increased CO oxidation activity was achieved due to the incorporated Mo. Stability of the composite-supported Pt catalyst was significantly higher than that of commercial Pt/C. Increased stability of the GNPs-GO-derived catalyst compared to the GNP-derived one was obtained. Full article

Sulfonated poly(ether ether ketone) (SPEEK) is one of the most studied ionic polymers for polymer electrolyte membranes (PEMs) in fuel cells (PEMFCs). To improve its proton conductivity, novel SPEEK/praseodymium-doped zinc spinel ferrite composite membranes of 130–170 μm thickness were prepared via ultrasound-assisted dispersion of various proportions of synthesized doped ferrite nanoparticles into the polymer solution, followed by a simple solution-casting method. The morphology (as observed by SEM and confirmed by DMA) and the conducted physical and chemical tests typical for PEMs, such as water uptake (32–44% at 80 °C), ionic exchange capacity (1.67–1.80 mEq/g), chemical (around 1% loss in Fenton reagent after 24 h), thermal stability (up to 190 °C) and tensile strength (39–50 MPa), were proven to depend on the content of inorganic filler in the composite (up to 5%). The proton conductivity of composite membranes (0.21–2.82 × 10⁻² S/cm at 80 °C) was assessed by broadband dielectric spectroscopy. The membrane with a content of 0.25 wt.% ZnFe_1.96Pr_0.04O₄ showed the best proton conductivity (3.41 × 10⁻² S/cm at 60 °C), as compared to 1.60 × 10⁻² S/cm for Nafion117 measured under the same conditions, demonstrating its suitability as a PEM for fuel cell applications. Full article

The proton-exchange membrane fuel cell (PEMFC) generates a significant reaction and ohmic heat during operation, imposing stringent cooling requirements. This study employs a three-dimensional, non-isothermal, steady multiphase multiphysics model to investigate heat generation and transport in a three-cell PEMFC stack using deionized water, CuO, and Al₂O₃ nanofluids (1 vol%) as coolants. The base (no-coolant) configuration was validated against a published polarization curve for a nine-cell stack. Introducing coolant channels increased the area-averaged current density from 2426 A m⁻² (no coolant) to 2613 A m⁻² (water), 2678 A m⁻² (CuO), and 2702 A m⁻² (Al₂O₃), representing up to an 11.4% performance improvement while reducing the peak cell temperature by approximately 7–8 °C. Among the examined coolants, Al₂O₃ nanofluid achieved the lowest maximum temperature and a favorable pressure drop, whereas water maintained the most uniform temperature field. A price-performance factor (PPF) was introduced to evaluate the techno-economic trade-off between cost and cooling benefit. This study highlights that, despite scale-related limitations between three-cell simulations and nine-cell experiments, nanofluid coolants offer a practical route toward thermally stable and high-performance PEMFC operation. Full article

Hydrogen-based technologies, prominently fuel cells, are emerging as strategic solutions for decarbonization. They offer an efficient and clean alternative to fossil fuels for electricity generation, making a tangible contribution to the European Green Deal climate objectives. The primary issue is the production and transportation of hydrogen. An on-site hydrogen production system that includes CO₂ capture could be a viable solution. The proposed power system integrates an internal combustion engine (ICE) with a steam methane reformer (SMR) equipped with a CO₂ capture and energy storage system to produce “blue hydrogen”. The hydrogen fuels a high-temperature polymer electrolyte membrane (HT-PEM) fuel cell. A battery pack, incorporated into the system, manages rapid fluctuations in electrical load, ensuring stability and continuity of supply and enabling the fuel cell to operate at a fixed point under nominal conditions. This hybrid system utilizes natural gas as its primary source, reducing climate-altering emissions and representing an efficient and sustainable solution. The simulation was conducted in two distinct environments: Thermoflex code for the integration of the engine, reformer, and CO₂ capture system; and Matlab/Simulink for fuel cell and battery pack sizing and dynamic system behavior analysis in response to user-demanded load variations, with particular attention to energy flow management within the simulated electrical grid. The main results show an overall efficiency of the power system of 39.9% with a 33.5% reduction in CO₂ emissions compared to traditional systems based solely on internal combustion engines. Full article

Anion exchange ionomer (AEI) binders are critical to the performance of alkaline electrochemical devices (i.e., fuel cells, electrolyzers, and batteries), as they facilitate ion transport, provide structural integrity, and improve the overall performance and lifespan of these devices. These binders not only ensure ion transport but also provide mechanical stability to the electrode materials. Recently, there has been significant progress in designing AEIs that are more compatible with existing electrode materials and electrolytes. This review summarizes the different types of AEI binders, focusing on their chemical structure, functionalization, conductivity, and how they affect the performance of alkaline fuel cells, specifically, anion exchange membrane fuel cells (AEMFCs). It also discusses how factors like functional groups, polymer backbone and side-chain flexibility, and ion exchange capacity balance conductivity, mechanical strength, and water uptake (WU). Recent advances in material design, such as polymer blends, composites, and crosslinked ionomers, as well as electrode setup, such as asymmetric ionomer electrodes, are explored as methods for improving stability and ion transport. The main challenges facing AEIs, including water management, alkaline degradation, phase separation, mechanical robustness, and long-term durability, are discussed along with strategies for overcoming them. Finally, we outline future research directions for developing scalable, economical solutions and integrating these binders with new electrode materials to help improve the performance and stability of next-generation AEMFCs. Full article