Search Results (447)

Laboratory data from in-cell tests at and near open circuit potentials (OCV) and ex-situ H₂O₂ vapor exposure tests are used to develop a fluoride emission rate (FER) model for a state-of-the-art 12-µm thin, low equivalent weight, long-chain perfluorosulfonic acid (PFSA) ionomer membrane that is mechanically reinforced with expanded PTFE and chemically stabilized with 2 mol% cerium as an anti-oxidant. The anode FER at OCV linearly correlates with O₂ crossover from the cathode and the high yield of H₂O₂ at anode potentials, as observed in rotating ring disk electrode (RRDE) studies. The cathode FER may be linked to the energetic formation of reactive hydroxyl radicals (·OH) from the decomposition of H₂O₂ produced as an intermediate in the two-electron ORR pathway at high cathode potentials. Both anode and cathode FERs are significantly enhanced at low relative humidity and high temperatures. The modeled FER is strongly influenced by the gradients in water activity and cerium concentration that develops in operating fuel cells. Membrane stability maps are constructed to illustrate the relationship between the cell voltage, temperature, and relative humidity for FER thresholds that define H₂ crossover failure by chemical degradation over a specified lifetime. Full article

Polymer electrolyte membrane fuel cells (PEMFCs) are emerging as the next-generation powertrain for unmanned aerial vehicles (UAVs) due to their high energy density and long operating duration. PEMFCs are subject to icing and performance degradation problems at sub-zero temperatures, especially at high altitudes. Therefore, an effective preheating system is required to ensure stable PEMFC operation in high-altitude environments. This study aimed to mathematically model a shell-and-tube heat exchanger that utilizes waste heat recovery to prevent internal and external PEMFC damage in cold, high-altitude conditions. The waste heat from the PEMFC is estimated based on the thrust of the MQ-9 Reaper, and the proposed heat exchanger must be capable of heating air to −5 °C. As the heat exchanger utilizes only waste heat, the primary energy consumption arises from the coolant pumping process. Calculation results indicated that the proposed heat exchanger design improved the overall system efficiency by up to 15.7%, demonstrating its effectiveness in utilizing waste heat under aviation conditions. Full article

The Holby–Morgan model of electrochemical degradation in platinum on a carbon catalyst is studied with respect to the impact of particle size distribution on aging in polymer electrolyte membrane fuel cells. The European Union harmonized protocol for testing by non-symmetric square-wave voltage is applied for accelerated stress cycling. The log-normal distribution is estimated using finite size groups which are defined by two parameters of the median and standard deviation. In the non-diffusive model, the first integral of the system is obtained which reduces the number of differential equations. Without ion diffusion, it allows to simulate platinum particles shrank through platinum dissolution and growth by platinum ion deposition. Numerical tests of catalyst degradation in the diffusion model demonstrate the following changes in platinum particle size distribution: broadening for small and shrinking for large medians with tailing towards large particles; the possibility of probability decrease as well as increase for each size group; and overall, a drop in the platinum particle size takes place, which is faster for the small median owing to the Gibbs–Thompson effect. Full article

This study investigates the effects of anode and cathode inlet flow rates (ṁ) on the power performance of bipolar plates in a polymer electrolyte membrane fuel cell (PEMFC). The primary objective is to derive optimal flow rate conditions by comparatively analyzing concentration loss in the I−V curve and crossover phenomena at the anode, thereby establishing flow rates that prevent reactant depletion and water flooding. A single-cell computational model was constructed by assembling a commercial bipolar plate with a gas diffusion layer (GDL), catalyst layer (CL), and proton exchange membrane (PEM). The model simulates current density generated by electrochemical oxidation-reduction reactions. Hydrogen and oxygen were supplied at a 1:3 ratio under five proportional flow rate conditions: hydrogen (${\dot{m}}_{H_2}$ = 0.76–3.77 LPM) and oxygen (${\dot{m}}_{O_2}$ = 2.39–11.94 LPM). The Butler–Volmer equation was employed to model voltage drop due to overpotential, while numerical simulations incorporated contact resistivity, surface permeability, and porous media properties. Simulation results demonstrated a 24.40% increase in current density when raising ${\dot{m}}_{H_2}$ from 2.26 to 3.02 LPM and ${\dot{m}}_{O_2}$ from 7.17 to 9.56 LPM. Further increases to ${\dot{m}}_{H_2}$ = 3.77 LPM and ${\dot{m}}_{O_2}$ = 11.94 LPM yielded a 10.20% improvement, indicating that performance enhancements diminish beyond a critical threshold. Conversely, lower flow rates (${\dot{m}}_{H_2}$ = 0.76 and 1.5 LPM, ${\dot{m}}_{O_2}$ = 2.39 and 4.67 LPM) induced hydrogen-depleted regions, triggering crossover phenomena that exacerbated anode contamination and localized flooding. Full article

This paper presents a robust optimization-based approach for voyage and power generation scheduling to enhance the economic efficiency and reliability of electric propulsion ships powered by polymer electrolyte membrane fuel cells (PEMFCs) and battery energy storage systems (BESSs). The scheduling method is formulated considering generation cost curves of PEMFCs with mixed-integer linear programming (MILP) and is extended to a robust optimization framework that accounts for marine environmental uncertainties. The robust optimization approach, implemented via the column-and-constraint generation (C&CG) method, ensures stable operation under various uncertainty scenarios, such as wave speed and direction influenced by wind and tidal currents. To validate the proposed method, a simulation was conducted under realistic operational conditions, followed by a case study comparing the MILP and robust optimization approaches in terms of economic efficiency and reliability. Additionally, the optimization model incorporated degradation costs associated with PEMFCs and BESSs to account for long-term operational efficiency. The case study assessed the performance of both methods under load variation scenarios across different marine environmental uncertainties. Full article

This study evaluates the tribological behavior of two elastomeric sealing materials—EPDM and TPV—sliding against 30 wt.% glass fiber-reinforced polyamide 66 (PA66GF30), a composite widely used in structural and guiding components. The application context is low-leakage valve systems in polymer electrolyte membrane fuel cells (PEMFCs), particularly on the cathodic (air) side, where dry contact and low-friction sealing are critical. Pin-on-disk tests were conducted under three normal loads (1, 3, and 6 N) and sliding speeds of approximately 0.05, 0.10, and 0.15 m/s (92, 183, and 286 RPM). The coefficient of friction (CoF), mass loss, and wear morphology were analyzed. TPV generally exhibited lower and more stable friction than EPDM, with CoF values exceeding 1.0 at 1 N but falling within 0.32–0.52 under typical operating conditions (≥3 N). EPDM reached a maximum mass loss of 0.060%, while TPV remained below 0.022%. Microscopy revealed more severe wear features in EPDM, including tearing and abrasive deformation, whereas TPV surfaces displayed smoother, more uniform wear consistent with its dual-phase morphology. These findings support the selection of TPV over EPDM in dry-contact sealing interfaces involving composite counterfaces in PEMFC systems. Full article

Proton exchange membrane fuel cell (PEMFC) fault diagnosis faces two critical limitations: conventional offline methods lack real-time predictive capability, while existing prediction approaches are confined to single fault types. To address these gaps, this study proposes an online multi-fault prediction framework integrating three novel contributions: (1) a sensor fusion strategy leveraging existing thermal/electrochemical measurements (voltage, current, temperature, humidity, and pressure) without requiring embedded stack sensors; (2) a real-time sliding window mechanism enabling dynamic prediction updates every 1 s under variable load conditions; and (3) a modified CNN-based Bi-LSTM parallel model with attention mechanism (ConvBLSTM-PMwA) architecture featuring multi-input multi-output (MIMO) capability for simultaneous flooding/air-starvation detection. Through comparative analysis of different neural architectures using experimental datasets, the optimized ConvBLSTM-PMwA achieved 96.49% accuracy in predicting dual faults 64.63 s pre-occurrence, outperforming conventional LSTM models in both temporal resolution and long-term forecast reliability. Full article

In polymer electrolyte membrane fuel cells (PEMFCs), substantial efforts have been made to focus on Pt and Pt alloy catalysts to enhance their catalytic performance. However, these catalysts still fail to meet practical requirements and existing PtCo catalysts face durability issues due to structural limitations. In this study, carbon-supported hybrid PtCo alloy catalysts (H-PtCo) with improved activity and durability are synthesized by reducing Co precursors onto pre-formed colloidal Pt nanoparticles. Elemental mapping via transmission electron microscopy reveals that the H-PtCo catalysts exhibit a high concentration of Co atoms near the sub-surface. This Co enrichment results from the conformal deposition of Co atoms onto Pt nanoparticles, followed by high-temperature treatment. Electrochemical characterizations, including linear sweep voltammetry (LSV) and accelerated durability test (ADT), demonstrate that the H-PtCo catalysts outperform conventional PtCo alloys (C-PtCo), synthesized via the co-reduction method of Pt and Co, in terms of oxygen reduction reaction (ORR) activity and stability. Furthermore, single-cell tests reveal that the H-PtCo catalysts significantly enhance both performance and durability compared to C-PtCo and Pt catalysts. These findings emphasize the critical role of Co atom distribution within PtCo nanoparticles in improving catalytic efficiency and long-term stability. Full article

An efficient adaptive modeling criterion for the polymer electrolyte membrane fuel cell (PEMFC) is proposed in this paper, which can facilitate its precise simulation, design, analysis and control. In this work, a number of state-of-the-art algorithms have been adapted to optimize the complex electrochemical PEMFC model. Investigations are carried out not only from the conventional perspective of modeling accuracy but also from a new perspective represented by the impact of process computational time. Here, a novel technique of PEMFC modeling is proposed based on a meta-heuristic optimization algorithm called the wild horse optimizer (WHO). The proposed technique is concerned with the impact of the computational time on dynamic PEMFC modeling. A comprehensive statistical analysis was performed on the results of competing meta-heuristic optimizers that were adapted to a common PEMFC modeling problem. Among them, the proposed WHO approach’s results showed a promising performance in terms of its accuracy and minimum computational time over the other state-of-the-art approaches. For further evaluation of the WHO approach, it was used to optimize additional commercial PEMFC stack models. The results of the WHO approach highlighted its superior performance from the point of view of a high accuracy with a low computational burden, which supports its suitability for online applications. Full article

This review is focused on FC-BENTEN, an advanced synchrotron X-ray experimental database developed at SPring-8 with support from Japan’s New Energy and Industrial Technology Development Organization (NEDO). Designed to advance polymer electrolyte fuel cells (PEFCs) research, FC-BENTEN addresses challenges in improving efficiency, durability, and cost-effectiveness through data-driven approaches informed by materials informatics (MI). Through standardization of protocols for sample preparation, data acquisition, analysis, and formatting, the database ensures high-quality, reproducible data essential for reliable scientific outcomes. FC-BENTEN streamlines metadata creation using automated processes and template-based tools, enhancing data management, accessibility, and interoperability. Security measures include two-factor authentication, safeguarding sensitive information and maintaining controlled user access. Planned integration with MI platforms will broaden data cross-referencing capabilities, facilitate PEFC applications expansion, and guide future research. This review discusses FC-BENTEN’s architectural framework, metadata standardization efforts, and role in advancing PEFC research through a high-throughput experimental workflow. It illustrates how data-driven methods and standardized practices contribute to innovation, underscoring databases’ potential to accelerate next-generation PEFC technologies development. Full article

In the development of more electric aircraft, hydrogen powered fuel cells are one possible solution to progress towards emission reductions in aviation. Currently, there are numerous concepts for integrating fuel cells into future aircraft. The goal of this work was to develop a dynamic fuel cell model for simulations of the powertrain. The Modelica language together with the ThermoFluidStream (TFS) library from the German Aerospace Center (DLR) provided a suitable framework. The fuel cell model takes into account the electrochemical as well as thermodynamic behavior. Hence, the proposed multi-physics model allows simulating the whole fuel cell system, from the hydrogen tank to the electric grid. Under certain simplifications, this enables performing mission simulations of the complete powertrain of future aircraft. As such, polymer electrolyte membrane (PEM) fuel cells and solid oxide fuel cells (SOFC) were considered. The fuel cell models are checked for plausibility in a simple test case against data from the literature. Furthermore, two setups of possible applications are introduced: one for each fuel cell type, which come from two projects. The preliminary control systems of these architectures are presented. Afterwards, the first results of the fuel cell systems are discussed. These results show that the models ran robustly in various environments and operational states. They provided the desired accuracy to predict the behavior of a fuel cell, while maintaining low CPU times and being capable of enabling real-time simulations in the future. Full article

This study investigates the potential for affordable and lightweight polymer electrolyte membrane fuel cells (PEMFCs) using lightweight flow-field plates, also referred to as bipolar plates. A comparative analysis was conducted on the performance of metal-coated and uncoated three-dimensional (3D)-printed flow-field plates, as well as that of a conventional graphite flow-field plate. The fabrication of these lightweight flow-field plates involved the application of sputtering and 3D printing technologies. The polarization curves and corresponding electrochemical impedance spectra of PEMFCs with metal-coated 3D-printed, uncoated 3D-printed, and graphite flow-field plates were measured. The results demonstrate that the metal-coated 3D-printed flow-field plate exhibits a gravimetric power density of 5.21 mW/g, while the graphite flow-field plate registers a value of 2.78 mW/g, representing an 87.4% improvement in gravimetric power density for the metal-coated 3D-printed flow-field plate compared to the graphite flow-field plate. These findings suggest the feasibility of reducing the weight of PEMFCs using metal-coated 3D-printed flow-field plates. Full article

Proton exchange membrane fuel cells (PEMFCs) are pivotal to advancing sustainable hydrogen energy systems. However, their performance decreases under low-humidity conditions (relative humidity, RH 50%) due to inadequate membrane hydration. This study addresses this challenge by utilizing a sputtering process to deposit titanium dioxide (TiO₂) onto microporous layers (MPLs), enhancing their hydrophilicity and water management capabilities. TiO₂ intrinsic hydrophilic properties and oxygen vacancies improve water adsorption and distribution, leading to more stable PEMFC performance under reduced humidity. Electrochemical evaluations revealed that while initial resistance slightly increased, long-term stability improved significantly. The TiO₂-coated MPL exhibited a lower performance degradation rate, with a 12.33% reduction in current density compared to 25.3% for the pristine MPL after 10 h of operation. These findings demonstrate that TiO₂ deposition effectively mitigates performance losses under low-humidity conditions, reducing the reliance on external humidification systems. This work contributes to the development of more efficient and sustainable fuel cell technologies for applications such as hydrogen-powered vehicles and distributed energy systems. Full article

This study presents the integration and evaluation of commercially available gas diffusion electrodes (GDEs), specifically designed for high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) within membrane electrode assemblies (MEA) for electrochemical hydrogen pump/compressor applications (EHP/C). Using Nafion 117 as a solid polymer electrolyte, the MEAs were analyzed for cell efficiency, hydrogen evolution, and hydrogen oxidation reactions (HER and HOR) under differential pressure up to 16 bar and a temperature ranging from 20 °C to 60 °C. Key properties of the GDEs, such as electrode thickness and conductivity, were investigated. The catalytic layer was characterized via XRD and EDX analyses to assess its surface and bulk composition. Additionally, the effects of increasing MEA’s geometric size (from 1 cm² to 5 cm²) and hydrogen crossover phenomena on the efficiency were examined in a single-cell setup. Electrochemical performance tests conducted in a single electrochemical hydrogen pump/compressor cell under hydrogen flow rates from 36.6 Ml·min⁻¹·cm⁻² to 51.3 mL·min⁻¹ cm⁻² at atmospheric pressure provided insights into the optimal operational parameters. For a double-stage application, the MEAs demonstrated enhanced current densities, achieving up to 0.6 A·cm⁻² at room temperature with further increases to 1 A·cm⁻² at elevated temperatures. These results corroborated the single-cell data, highlighting potential improvements in system efficiency and a reduction in adverse effects. The work underscores the potential of HT-PEMFC-based GDEs for the integration of MEAs applicable to advanced hydrogen compression technologies. Full article

Solid electrolytes, including polymer electrolytes, are a promising option for improving the performance of environmentally friendly batteries such as rechargeable lithium-ion batteries or fuel cells. Hydrogen–oxygen fuel cells producing only water under power generation are attracting widespread attention, and they need proton conductors as electrolytes. Fluoropolymer electrolytes such as Nafion^® have been utilized for hydrogen–oxygen fuel cells below 100 °C; however, they are not applicable over the working temperature. Therefore, other types of polymer electrolytes are demanded for hydrogen–oxygen fuel cells. Polyoxometalate (POM) inorganic clusters are known as proton conductors and are utilized to prepare POM–polymer composites for solid electrolyte application. In such POM–polymer composites, distinct compositions and structures are significant for improving the performance of proton conductivity. Recently, POM–polymer composites with distinct compositions and structures have been synthesized to obtain high proton conductivity. The key factor is to use single-crystalline compounds. Here, several examples are overviewed by classifying them into three categories: (i) single-crystalline POM–polymer composites, (ii) organically modified POM (org-POM) polymers, and (iii) POM hybrid polymers using polymerizable cations. The application of proton-conductive solid electrolytes is focused on. Full article