Fuel Cells最新文献

In a polymer electrolyte membrane (PEM) fuel cell, the following degradation mechanisms are associated with the catalyst particles and their support: carbon support corrosion triggered by carbon and platinum oxidation, platinum dissolution with redeposition, and particle detachment with agglomeration. In this work, an electrochemical model for those degradation effects is presented as well as its coupling with a three-dimensional computational fluid dynamics PEM fuel cell performance model. The overall model is used to calculate polarization curves and current density distributions of a PEM fuel cell in a fresh and aged state as well as the degradation process during an accelerated stress test with 30 000 voltage cycles. The obtained simulation results are compared to measurements on a three-serpentine channel PEM fuel cell with an active area of 25 cm² under various temperatures and humidities. The experimental data are obtained with a segmented test cell using respective degradation protocols and test conditions proposed by the United States Department of Energy. In addition to the temperature and humidity changes, the influence of geometry and material parameters on the degree of degradation and the resulting fuel cell performance is explored in detail.

Traditional wastewater treatment plants (WWTPs) consume a significant amount of energy to clean wastewater. However, for medium- and small-scale WWTPs, it is crucial to have an energetically self-sustained treatment. In this regard, novel low-energy demand treatment systems, such as nature-based solutions (NBS), are highly suitable alternatives. Constructed wetlands coupled with microbial fuel cells (MFC), referred to as electrowetlands (EWs), are NBS able to treat wastewater while recovering electricity. In this study, initially, various granular carbon materials were tested as anode materials in laboratory-scale MFCs, and anthracite was selected due to its higher electrochemical activity. Then, pre-pilot scale tests were conducted, evaluating different EW configurations. The one consisting in a horizontal anode yielded the best wastewater treatment efficiencies (chemical oxygen demand [COD] degradation greater than 90%) and electricity production (11 mW m⁻²; 260 mWh day⁻¹ m⁻²). Finally, a 50 m² pilot was constructed in Valladolid, studying its performance under real conditions for 1 year. The pilot showed robust and stable performance, achieving high wastewater treatment efficiencies (COD degradation >85%, outflow COD of 100 ppm) and generating 115 Wh in 1 year (power density of 0.4 mW m⁻²).

Traditional automotive proton exchange membrane fuel cell (PEMFC) endurance testing relies on the fuel cell (FC) dynamic load cycle (FC-DLC) protocol, which inadequately reflects real-world driving conditions. To address this limitation the “Investigations on degradation mechanisms and Definition of protocols for PEM Fuel cells Accelerated Stress Testing” (ID-FAST) consortium defined the new representative “ID-FAST driving load cycle,” a novel approach capturing the load distribution, transitions, temperature variations, and humidity fluctuations experienced by FCs in real-world operation. We demonstrate the ID-FAST driving cycle itself and the integration into a realistic durability test program for FC test benches and present the resulting test data. Furthermore, we showcase its implementation within an accelerated stress testing (AST) protocol, highlighting its potential to significantly reduce testing time by accelerating degradation. Additionally, a novel method for highly dynamic humidity adjustment within test benches is introduced. By overcoming limitations of existing methods and incorporating the ID-FAST driving cycle, this work paves the way for a new era of efficient and realistic FC endurance testing, ultimately contributing to the development of more robust and durable automotive FC stacks.

The porosity of the gas diffusion layer (GDL) significantly impacts the performance of proton exchange membrane fuel cells (PEMFCs). Assembly pressure in PEMFCs leads to GDL deformation and alterations in porosity distribution. This study integrated a three-dimensional (3D) GDL deformation model with a 3D two-phase PEMFC model, employing a four-term Fourier series model to optimize the fitting of the GDL porosity distribution curve. The approach quantitatively assessed the impact of GDL porosity distribution under assembly pressure on PEMFC performance. Results reveal an arched porosity distribution in GDL, peaking in the middle of low channels adjacent to ribs. High porosity enhances oxygen and heat conduction but excessive porosity may cause uneven current density distribution, hindering GDL drainage. Furthermore, the analysis compares performances at various GDL compression ratios and thicknesses, showing an initial rise then fall in current density with increasing pressure. This represents a trade-off between the adverse impact of GDL compression on mass transfer losses and the favorable impact of reduced ohmic losses. At the optimal pressure, the current density is 3% higher than neighboring values at the same potential, and within the optimal GDL thickness range, the current density error remains below 1%.

The electrochemical operation of membrane electrode assemblies (MEAs) with different Nafion/C composition (0%, 20%, 30%, 40%, and 50%) and the same ultralow platinum load (0.02 mg_Pt cm⁻²) has been investigated. The electrodes were manufactured by depositing the catalytic ink, prepared with catalyst HiSPEC9100, onto the gas diffusion layers by wet powder spraying. MEA with 30% Nafion/C reached the highest power density (675 mW cm⁻²) and the lowest mass of Pt per power (0.059 g_Pt kW⁻¹) under H₂/O₂ 2 bar gauge pressure, the last quotient being 1.7 time less than USDRIVE objective for 2025. The electrochemical functioning of current membrane-electrode setups is compared with an analogous series with thicker electrode catalytic layer prepared with a commercial catalyst with a lower percent of Pt/C. Scanning electron microscopy characterization analysis of catalytic layers prepared by wet spraying exhibited an ionomer homogeneous network.