PEM Fuel Cell Performance Research Articles

Analysis of the Impact of Dynamic Operation of PEMFCs for Ship Applications

<i>Dynamic responses of polymer electrolyte membrane fuel cells (PEMFC) were analyzed under varying loads to understand the performance of PEMFCs for ship applications. Experiments employing single cells were conducted under a static load with a constant current of 6.64 A and dynamic loads at a ramp rate of 2.5%/s and 5.0%/s, representing a simplified ship operation condition. Under the static load, the voltage drop was 0.054 V at 1.00 A/cm<sup>2</sup> and was dominant below 0.40 A/cm<sup>2</sup>. In contrast, under the dynamic load (5.0%/s ramp rate), the voltage drop was 0.061 V at 1.00 A/cm<sup>2</sup> and was dominant above 0.40 A/cm<sup>2</sup>, with similar behavior observed at the ramp rate of 2.5%/s. To compare performance across load conditions, degradation rates were calculated through linear regression of the voltage drop for each current density. The degradation rate at 1.00 A/cm<sup>2</sup> was 0.143 mV/h under static load conditions and 0.174 mV/h under dynamic load conditions (ramp rate: 5.0%/s), indicating approximately 21% greater degradation rates than those observed under static load conditions. These experimental results provide foundational data for PEMFC performance analysis, particularly regarding performance degradation caused by dynamic loads in marine environments.</i>

Exploring the Potential of Bimetallic PtPd/C Cathode Catalysts to Enhance the Performance of PEM Fuel Cells.

Bimetallic platinum-containing catalysts are deemed promising for electrolyzers and proton-exchange membrane fuel cells (PEMFCs). A significant number of laboratory studies and commercial offers are related to PtNi/C and PtCo/C electrocatalysts. The behavior of PtPd/C catalysts has been studied much less, although palladium itself is the metal closest to platinum in its properties. Using a series of characterization methods, this paper presents a comparative study of structural characteristics of the commercial PtPd/C catalysts containing 38% wt. of precious metals and the well-known HiSpec4000 Pt/C catalyst. The electrochemical behavior of the catalysts was studied both in a three-electrode electrochemical cell and in the membrane electrode assemblies (MEAs) of hydrogen-air PEMFCs. Both PtPd/C samples demonstrated higher values of the electrochemically active surface area, as well as greater specific and mass activity in the oxygen reduction reaction in comparison with conventional Pt/C, while not being inferior to the latter in durability. The MEA based on the best of the PtPd/C catalysts also exhibited higher performance in single tests and long-term durability testing. The results of this study conducted indicate the prospects of using bimetallic PtPd/C materials for cathode catalysts in PEMFCs.

Modeling of Catalyst Degradation in Polymer Electrolyte Membrane Fuel Cells Applied to Three‐Dimensional Computational Fluid Dynamics Simulation

ABSTRACTIn 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.

A comprehensive modeling, analysis, and optimization of two phase, non–isobaric, and non–isothermal PEM fuel cell

This study models a non-isobaric, non-isothermal two-phase flow in a Polymer Electrolyte Membrane Fuel Cell (PEM-FC), focusing on conservation equations for mass, energy, and momentum across its components. Verification involves comparing PEM-FC performance and temperature distribution with experimental and literature data, showing consistent agreements. Results indicate that increasing cathode channel pressure enhances membrane moisture and reduces power loss. Higher oxygen partial pressure improves PEM-FC performance, whereas increased anode channel pressure heightens ohmic losses and lowers output voltage. Temperature distribution reveals highest temperatures near the cathode catalyst layer due to electrochemical reactions. Adjusting pressures in cathode and anode channels affects these temperatures accordingly. PEM-FC power density is optimized using various algorithms, with simulated annealing proving most effective. Optimal values for gas diffusion layer thickness, electrode porosity, and inlet humidity are determined. Under constant current density, power density increases by 6 % compared to baseline conditions, demonstrating effective parameter optimization for enhancing PEM-FC performance.

Study on the impact of active intake air fluctuation on the performance and mass transfer of PEM Fuel Cell

Enhancing mass transfer is imperative for mitigating concentration polarization and thereby optimizing fuel cell performance. This study presents numerical investigation to explore the performance of a proton exchange membrane fuel cell, which involves implementation of actively controlled fluctuating mass fluxes at cathode inlet in order to achieve desirable mass transfer enhancement. The trajectories of liquid droplets within channel were predicted by employing volume of fluid method. The results revealed that the current density exhibits frequency-dependent fluctuations, aligning with input oscillations. A marginal increase in mean current density was observed with frequency amplified and the maximum power density with fluctuated flow increased by 3.9 % compared to that with steady flow inlet. A noteworthy and linear augmentation was evident with amplitude escalation. The mean current density surpassed 34.7 % of the steady current at the amplitude of 10. Beyond a frequency threshold of 1000 Hz, the fluctuating current density surpassed that of steady flow throughout the entire period, attributed to the time constant of gas transport within the gas diffusion layer. Moreover, fluctuation phenomenon of the pressure field within the fuel cell channel, which contributed to reinforced mass transfer and accelerated product alleviation in the region facing bipolar rib was identified during gas transport in the gas diffusion layer. Numerical simulations adopting the volume of fluid method revealed a heightened tendency for the disintegration and expulsion of liquid droplets in the channel attributable to fluctuating flow.

Assessing PEM fuel cell performance in a geothermal Cogeneration system for peak-time energy storage

In this investigation, a novel geothermal power plant was designed, combining absorption chiller units, PEMFC, EPEM, and ORC. We conducted a comprehensive case study across four continents—Asia, Oceania, Europe, and America—leveraging weather data from various cities to evaluate the system's efficacy. Our modeling utilized EES (Engineering Equation Solver) software, optimizing the setup via the RSM with three key objective functions: exergy efficiency, hydrogen production, and cost rate. The primary focus was on delivering electricity to residential properties during peak demand periods. Exploring six scenarios for organic fluids in organic Rankine cycles, we gauged energy, exergy, and overall system performance. The TOPSIS method led us to select scenario 3, employing R123 and R134a refrigerants, as the optimal choice. The results of the optimization showcased impressive figures: an exergy efficiency of 81.816%, a hydrogen production rate of 25.119 kg/h, and a cost rate of 15.967 $/h for the system's most efficient configuration. Economic analysis highlighted the organic Rankine cycle units 1 and 2 as the components with the highest costs. Our evaluation extended to various cities—Aomori, Grosseto, Lhasa, Wellington, and San Diego—assessing the electricity, heating, and cooling needs of residential complexes based on the system's performance.

Investigating the Impact of Air Pollutants on Fuel Cell Performance and Durability: Experimental and Modeling Approaches

Fuel cells hold immense promise as efficient and sustainable power sources for transportation and stationary applications. However, their operation can be severely impacted by air pollutants, particularly sulfur dioxide (SO2) and nitrogen oxides (NOx). These pollutants can adsorb onto the platinum catalyst, leading to a decrease in fuel cell performance and durability.In this study, we investigate the impact of SO2 and NO2 on PEM fuel cell performance and durability. The contamination tests were carried out at a constant current density of 0.5 A.cm−2, and they consisted of four steps: a pre-poisoning step to evaluate initial performance (15-16 h), poisoning step (50 h), self-recovery in a pure air stream (20-21 h) and a driven CV-induced recovery. Electrochemical characterizations were carried out at the end of each step (Polarization curve, Electrochemical Impedance Spectroscopy, Cyclic Voltammetry and H2 Crossover). Our initial investigation involved contaminating a single fuel cell with a low concentration of 0.1 ppm of sulfur dioxide (SO2). Remarkably, this resulted in a 1.1% decrease in cell voltage. Building on this foundation, our ongoing research aims to delve deeper into the impact of individual pollutant concentrations (SO2 and NO2) and their combined effects, considering varying temperatures and current densities to simulate real-world conditions.Simultaneously, a comprehensive model is being developed using Simscape in Matlab. The model accounts for the pollutants either as single-component gases or as a mixture. For single-component gas adsorption, the Langmuir Isotherm model is employed. To capture the competitive adsorption of SO2 and NO2 on platinum in gas mixtures, we are testing the Modified Competitive Langmuir Isotherm Model. The model will further be calibrated and validated using the experimental results.This combined experimental and modeling approach will provide a comprehensive understanding of the impact of air pollutants on fuel cell performance and durability. The insights gained from this study can inform the development of mitigation strategies and enhance the robustness of fuel cells in real-world applications as well as the sizing of a filter. Figure 1

Improving polymer electrolyte membrane fuel cell performance and preventing flooding by exciting gas flow

Effective water management is necessary to prevent the performance degradation of polymer electrolyte membrane fuel cells (PEMFCs). In this study, acoustic pressure waves (AWs) are superimposed on an oxygen gas flow passing through a cathode to evaluate its potential to mitigate the flooding issue in flow channels. The goal is to expedite droplet removal by exciting droplets at frequencies close to their natural frequency. In-situ experiments are conducted to investigate the influence of AWs on two-phase flows in the cathode channel and the corresponding PEMFC performance. When AWs are applied, the frequency of water discharge from the cathode channel increases, and reduces the internal accumulated water, resulting in the pressure drop decreases. The internal flooding is also decreased, resulting in the reduction of the high frequency resistance attributed to decreased contact resistance. The external excitation improves the PEMFC performance owing to the effective and frequent water discharge induced by the increase in the local inertial force related to the droplet oscillation. The water management method propose in this study is considered to be an efficient method not only for PEMFC systems but also for other systems requiring water management.

Investigating the Role of Flow Plate Surface Roughness in Polymer Electrolyte Membrane Fuel Cells with the Use of Multiphysics Simulations

This study investigates the influence of surface roughness on the performance of polymer electrolyte membrane fuel cells (PEMFCs) through computational simulations using COMSOL Multiphysics. Two distinct gas flow channel (GFC) models of serpentine and parallel GFC structures were analysed, featuring various surface roughness levels to examine their impact on gas pressure and velocity dynamics. Rough surfaces are modeled using trigonometric functions to replicate machining-induced variations. Finite element simulations were conducted, assessing the time-dependent relationship between gas pressure and velocity while considering different electrode phase potentials as a function of surface roughness. Rough surfaces generally enhance mass transport, water management, and current distribution compared to smooth surfaces. The results indicated that a surface roughness of approximately 1 µm optimizes PEMFC performance by balancing pressure and velocity, enhancing electrochemical reactions, and reducing excessive pressure drops within the cell. Notably, the 0.7 V operating voltage was found to be the most efficient, achieving rapid stabilization of pressure and velocity levels swiftly. The findings underscore the importance of precise control over GFC roughness to enhance PEMFC performance gains in commercial applications, especially when multiple cells are stacked to achieve high power outputs.

In-Situ Characterization of Cathode Catalyst Degradation in PEM Fuel Cells

The composition and morphology of the cathode catalyst layer (CCL) have a significant impact on the performance and stability of polymer electrolyte membrane fuel cells (PEMFC). Understanding the primary degradation mechanism of the CCL and its influencing factors is crucial for optimizing PEMFC performance and durability. Within this work, we present comprehensive in-situ characterization data focused on cathode catalyst degradation. The dataset consists of 36 unique durability tests with over 4000 testing hours, including variations in the cathode ionomer to carbon ratio, platinum on carbon ratio, ionomer equivalent weight, and carbon support type. The applied accelerated stress tests were conducted with different upper potential limits and relative humidities. Characterization techniques including IV-curves, limiting current measurements, electrochemical impedance spectroscopy, and cyclic voltammetry were employed to analyse changes in performance, charge and mass transfer, and electrochemically active surface area of the catalyst. The aim of the dataset is to improve the understanding of catalyst degradation by allowing comparisons across material variations and provide practical information for other researchers in the field.

A Scalable and Robust Water Management Strategy for PEMFCs: Operando Electrothermal Mapping and Neutron Imaging Study.

Effective water management is crucial for the optimal operation of low-temperature polymer electrolyte membrane fuel cells (PEMFCs). Excessive liquid water production can cause flooding in the gas diffusion electrodes and flow channels, limiting mass transfer and reducing PEMFC performance. To tackle this issue, a nature-inspired chemical engineering (NICE) approach has been adopted that takes cues from the integument structure of desert-dwelling lizards for passive water transport. By incorporating engraved, capillary microchannels into conventional flow fields, PEMFC performance improves significantly, including a 15% increase in maximum power density for a 25 cm2 cell and 13% for a 100 cm2 cell. Electro-thermal maps of the lizard-inspired flow field demonstrate a more uniform spatial distribution of current density and temperature than the conventional design. Neutron radiography provides evidence that capillary microchannels in the lizard-inspired flow field facilitate the efficient transport and removal of generated liquid water, thereby preventing blockages in the reactant channels. These findings present a universally applicable and highly efficient water management strategy for PEMFCs, with the potential for widespread practical implementation for other electrochemical devices.

Impact of the flow-field distribution channel cross-section geometry on PEM fuel cell performance: Stamped vs. milled channel

Polymer electrolyte membrane fuel cells (PEM FCs) represent an essential part of the emerging hydrogen economy. Metallic bipolar plates (BPs) allow high speed and capacity production using established industrial technologies, like mechanical stamping. Stamping, however, leads to different cross-sectional shapes of flow-field (FF) channels as compared to milled or compression-moulded bipolar plates. The impact of these changes on the resulting fuel cell performance is not yet fully understood. This study employs an experimentally validated three-dimensional, isothermal, steady-state, continuum-mechanics based mathematical model to gain a deeper insight into this issue and to identify optimal stamped BP channel cross-sectional shapes for parallel and serpentine FF. The uniformity of the local distribution of the physico-chemical quantities and the resulting load curves are analysed. The results obtained confirm that stamped BPs with channels of the trapezoidal cross-section are a viable alternative to the traditional milled or moulded BPs with channels of the rectangular cross-section. The observed differences in performance of FC with stamped and milled channels can be mitigated by optimization of the channel cross-section geometry parameters. As an optimal rib width 0.4 mm and an optimal channel ground width 1 mm for milled and 0.2 mm for stamped BPs are suggested.

Effect of Number of Channels on Performance of PEM Fuel Cells for Serpentine Type Channel Configuration

Effect of Number of Channels on Performance of PEM Fuel Cells for Serpentine Type Channel Configuration

Trading Off Initial PEM Fuel Cell Performance versus Voltage Cycling Durability for Different Carbon Support Morphologies

Tailored design of carbon supports and their pore morphologies is crucial to achieve the ambitious durability and performance targets for future proton exchange membrane fuel cells (PEMFCs). We compared platinum catalysts supported on solid Vulcan carbon, porous Ketjenblack carbon, and accessible porous modified Ketjenblack carbon in a voltage cycling-based accelerated stress test (AST) with frequent intermittent characterizations. We derived how catalyst morphologies affect cell performance and electrochemical properties (electrode roughness factor, ORR activity, oxygen transport resistances) at beginning-of-life (BoL) and in various states of degradation up to 200,000 voltage cycles. We confirmed the enhanced Pt surface area retention of porous carbon-supported catalysts, ascribed to well-shielded Pt particles in internal pores, but find that this comes at the expense of lower initial high current density performance already at BoL. Accessible porous carbon-supported catalysts with wider pores mostly retain those durability benefits while, simultaneously, maximizing H2/air performance at all current densities due to improved oxygen transport. We also tracked changes in catalyst accessibility throughout voltage cycling by analyzing local oxygen transport resistances and relative humidity-dependent platinum utilization. We propose that catalysts with porous carbon supports undergo oxidative pore opening, followed by continuous migration of internal Pt particles to the external carbon surface.

Effect of manifold size on PEMFC performance with metal foam flow field

Metal foam flow fields are considered as an alternative to conventional channel/rib flow field in polymer electrolyte membrane fuel cell (PEMFC) because of the advantages of three-dimensional pore structure. In this study, the effect of metal foam flow field with different manifold size on PEMFC performance was investigated, with a 25 cm2 unit cell. Polarization curve and electrochemical impedance spectroscopy results were analyzed to investigate the effects of gas stoichiometry and relative humidity on performance. The mass transfer loss was decreased with reduced manifold size. However, mass transfer loss was increased due to difficulty of water discharge in small manifold case. The metal foam flow field offer advantages in water discharge and mass transfer loss. At 100% relative humidity, performance was improved with increased air stoichiometry for different manifold size. At 25% relative humidity, performance was a little improved with increased air stoichiometry for small manifold case. Regardless of relative humidity, fuel cell performance with metal foam flow field was most improved in case of smallest manifold size based on air stoichiometry due to the high pressure drop.

Investigation of Proton Exchange Membrane Fuel Cell Performance by Exploring the Synergistic Effects of Reaction Parameters via Power Curve and Impedance Spectroscopy Analysis

In this paper, a comprehensive analysis of the parameters that affect polymer electrolyte membrane fuel-cell performance is presented. Experiments were conducted on a single fuel cell membrane with an active area of 5 cm2. To study the fuel cell operation, parametric studies of temperature, pressure and relative humidity values were conducted under cyclic voltammetry for impedance analysis. The impact of the behavior of all three parameters on the fuel-cell performance were recorded and analyzed. As the temperature increased from 50 °C to 74 °C, the Pt catalyst surface areas demonstrated lower activation losses as the membrane conductivity increased. It is confirmed that an increase in temperature accompanied higher humidity levels to provide sufficient cell hydration that resulted in a higher performance output. The impedance measurements indicate that low humidity levels resulted in higher cell resistance and mass transport losses. As the back pressure increased, the membrane resistance decreased, which also reduced mass transport losses. The results indicate that the important factors affecting the fuel cell performance are mass transport limitation and membrane resistance. Based on the results of this study, the optimum performance can be achieved by operating at higher pressures and temperatures with humidified reactant gases.

Humidity impact on polarization dynamics in polymer electrolyte membrane fuel cells through distribution of relaxation times analysis

The interaction among relative humidity, current density, and internal polarization plays a crucial role in optimizing the performance of polymer electrolyte membrane fuel cells (PEMFCs). However, achieving swift analysis and feedback on the internal humidity status of PEMFCs through on-vehicle impedance spectroscopy measurements remains a significant challenge. Conducting a series of impedance spectra under operating conditions of 30 %, 50 %, and 80 % relative humidity sheds light on the impact of humidity on performance. Correlations between specific distribution of relaxation times (DRT) peaks and internal polarization are established. Through DRT analysis, four polarization dynamics related to proton transfer at the proton exchange membrane interface, proton transport in the cathode catalyst layer, charge transfer, and the oxygen diffusion process are effectively identified based on characteristic frequencies and peaks. The rate-determining step of the polarization varies under idling, rated, and overload conditions, providing valuable insights. This study contributes analytical models and strategic guidance for tailoring relative humidity conditions to mitigate polarization, thereby enabling real-time control and enhancement of PEMFC performance.

EIS study to analyse the influence of mechanical compression on the global PEM fuel cell performance

Proper clamping pressure is needed to guarantee the gas-tightness of PEMFC assembly and to enhance the contacts between components. Nevertheless, excessive mechanical load can deteriorate the cell performance, particularly by reducing the porosity and the mass transfer properties of the Gas Diffusion Layers (GDLs). In this study, the global performance of a 225 cm2 PEMFC assembly under mechanical stress (0.35–2 MPa) is investigated through Electrochemical Impedance Spectroscopy (EIS) as a complement to cell voltage monitoring and polarisation curves carried out previously. The analysis relies on the evolution, against mechanical compression, of the high and low frequency resistances, as well as the arc sizes of the EIS spectra. The measurements emphasise that mechanical loading primarily decreases ohmic losses, and they also highlight the importance of harmful physical phenomena at high frequencies. Ex-situ measurements (through-plane resistance of GDL) and in-situ results (high frequency resistance) show a similar reduction trend observed with increasing mechanical compression.

Experimental Design of High-Performing Open-Cathode Polymer Electrolyte Membrane Fuel Cells

Open-cathode polymer electrolyte membrane fuel cells (PEMFCs) utilize a unique air-cooled system design to eliminate the humidifiers, air compressor, and liquid cooling loop of conventional, liquid-cooled PEMFC systems, thereby greatly reducing system cost. However, the open-cathode PEMFC performance is restricted by poor humidification, high membrane and charge transfer resistances, and overheating due to inefficient thermal and water management. This work aims to strategically modify the membrane electrode assembly (MEA) design to overcome these issues and achieve high open-cathode PEMFC performance that approaches that of liquid-cooled systems. The use of thinner membrane along with short side chain ionomer is found to elevate the cell performance due to increased water retention at the cathode catalyst layer (CCL) and decreased ohmic losses. Thinner gas diffusion layers with high porosity enable additional cell performance increment by improving oxygen availability at the CCL. An overall current density rise of 88% at 0.6 V and 53% at 0.4 V is achieved by the strategically designed MEA for open-cathode cells. The enhanced power density enabled by the custom MEA can both reduce the stack cost and expand the power range of open-cathode PEMFCs, thus expanding their potential use for low-cost fuel cell system applications.

Unveiling the resistance component on fuel cell electrodes by ionic liquid adsorbed PtCo/C catalyst through distribution of relaxation time

A majority of studies focus on developing oxygen reduction reaction (ORR) catalysts and cathode configurations to enhance the performance and durability of polymer electrolyte membrane fuel cells (PEMFCs). In this study, resistance analyses of the membrane electrode assembly (MEA) are conducted to elaborate on the performance and durability improvements induced by the adsorption of [MTBD][beti] ionic liquid (IL) on the commercial PtCo/C catalyst. The morphological changes caused by IL adsorption are observed on micro and macro scales via physicochemical methods. From the half-cell measurement, when the 4 wt% IL was adsorbed, a 15 mV improvement in ORR activity occurred, and as the adsorption amount increased, the activity decreased. The MEA using 8 wt% IL adsorbed catalyst outperforms 1.7 times higher current density at 0.8 V and 40 % lower charge transfer resistance. Distribution of relaxation time resistance analysis reveals that oxygen mass transfer resistance (Rmass), ORR charge transfer resistance (RORR), and proton charge transfer resistance (Rproton) decrease due to IL adsorption. During accelerated durability tests, IL 8 % MEA showed a 58 % increase in durability, and a lower degradation of RORR and Rproton encouraged improved durability. The resistance analyses in this study contribute to identifying the factors responsible for the performance and durability enhancement of PEMFC.