Exchange Membrane Fuel Cell Performance Research Articles

Strategies for Improving Anion Exchange Membrane Fuel Cell Performance by Optimizing Electrode Conditions

We systematically study anion exchange membrane fuel cells (AEMFCs) based on poly(aryl-co-aryl piperidinium) (c-PAP) copolymers and provide a scalable scenario for high-performance AEMFCs, covering the optimization of the relative humidity (RH), catalyst species, catalyst interfaces, and hydrophobic treatment. Specifically, high-water-permeable c-PAP ionomers in the presence of moderate relative humidity (RH) (75%/100%) can be used to address anode flooding and cathode dry-out issues. The composition of the catalyst layer and the anode hydrophobic treatment significantly impact the power density of AEMFCs. c-PAP-based AEMFCs with optimum catalyst composition achieve a peak power density (PPD) of 2.70 W cm−2 at 80 °C in H2-O2 after hydrophobic treatment. Pt1Co1/C cathode-based AEMFCs reach a PPD of 1.80 W cm−2 along with an outstanding specific power of 13.87 W mg−1. Moreover, these AEMFCs can be operated under a 0.2 A cm−2 current density at 60 °C for over 300 h with a voltage decay rate of ∼300 μv h−1.

Towards Understanding the Evolution of Electrochemical Properties of Proton Exchange Membrane Fuel Cell Cathode And Performance Decay During Start-Up Phases Using Emulated Mitigation Strategies

Towards Understanding the Evolution of Electrochemical Properties of Proton Exchange Membrane Fuel Cell Cathode And Performance Decay During Start-Up Phases Using Emulated Mitigation Strategies

Investigation of the cross-section area geometry effect on the performance of PEM fuel cell

In this study, a proton exchange membrane fuel cell operating at low temperatures with a single channel is modeled. The prepared model has been compared with experimental data and its accuracy has been proved. Using this model, the impact of the change of the channel width on the cell performance with the channel height being constant and the change of the channel geometry with the channel cross-sectional area being constant was investigated. It has been found that the enlargement of the area where the reactant contacts the diffusion layer provides an increase in performance. However, when working at low voltages, it has been observed that increasing concentration losses decrease with increasing base angle and channel width.

Self-humidified operation of a PEM fuel cell using a novel silica composite coating method

A proton exchange membrane fuel cell operating with no external humidification support was successfully reported using a novel silica composite layer on the anode side (Pt/C/SiO2/Nafion). The nanosilica derived from tetramethoxy silane (TMOS) provided excellent porous morphology to retain water and hydrate protons. This layer provides a well-humidified environment for protons and easy proton transfer from the catalyst surface to the membrane electrolyte. The characteristics of the silica composite layer were investigated by various characterization methods: SEM, XRD, TEM, XPS, EIS, and TGA. A single cell fabricated with the anode containing this new silica composite layer showed a performance of 0.9 W/cm2 which is two folds greater when tested with the commercial catalyst MEA (0.45 W/cm2). MEA delivered a constant output power (at 0.6 V) under dry and humidified gas conditions which shows excellent electrochemical stability and durability.

Dual-layer catalyst layers for increased proton exchange membrane fuel cell performance

The use of a dual-layer cathode catalyst layer improves the performance of proton exchange membrane fuel cells. To generate single and dual-layer catalyst layers between the gas diffusion media and proton exchange membrane electrolyte, two commercial carbon-supported platinum catalysts with either a high microporosity carbon (Ketjen Black EC-300J) or a low porosity carbon (XC-72 Vulcan carbon) are utilized. We discovered that dual-layer cathode catalyst layers boost maximum power of fuel cells regardless of carbon porosity directionality, with either high surface area carbon at the proton exchange membrane electrolyte or gas diffusion media interface. At 25% relative humidity, a condition that generally inhibits fuel cell performance, a 20% performance boost is realized when using dual-layer cathode CLs. The electrochemical impedance spectroscopy results indicate that cathodes with dual-layer catalyst layer aid in water management due to lower kinetic activity losses of the Pt and improved hydration of the proton exchange membrane electrolyte.

Influence of the synthesis parameters on the proton exchange membrane fuel cells performance of Fe–N–C aerogel catalysts

Fe–N–C aerogel catalysts were prepared by sol–gel polycondensation of resorcinol, melamine and formaldehyde precursors in the presence of FeCl 3 salt, followed by supercritical drying and thermal treatments. The effect of the mass ratio of precursors on the microstructure, iron speciation and oxygen reduction reaction (ORR) performance of the Fe–N–C aerogels was investigated by N 2 sorption, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, X-ray absorption spectroscopy, CO chemisorption and rotating disk electrode in acidic medium. The best ORR performance (activity and mass transport) was obtained by an optimum balance between pore structure and active Fe-N x species. Through acid washing, the durability of the catalyst was further improved by eliminating unstable and inactive species, particularly iron nanoparticles and iron carbide. From the CO chemisorption and turnover-frequency value, the surface sites were comparable with the highest values reported in literature. Finally, Fe–N–C aerogel catalyst was implemented a in membrane–electrode assembly with an active area of 25 cm 2 and tested in single cell, emphasizing the importance of the ink formulation on the performance. • Optimum balance between pore texture and active FeNx species for best ORR performance. • Better mass-transport properties due to higher mesopore volume in the Fe–N–C catalyst. • XAS and 57 Fe Mössbauer spectroscopies identified FeN x and Fe-inorganic species. • Acid washing treatment eliminates the unstable and inactive Fe-inorganic species. • Need to adapt the ink formulation to the catalyst texture for high performance MEAs.

Exploration of operating conditions on oxygen mass transport resistance and performance of PEM fuel cells: Effects of inlet gas humidification

AbstractThis work presents comprehensive studies of inlet gas humidification on O2 mass transport and proton exchange membrane fuel cell performance to obtain a better understanding of transport processes at a cathode gas diffusion electrode. The O2 mass transport resistance was determined employing our segmented cell system and a novel method based on the distribution of the spatial limiting currents using 5% vol. O2 mixtures with various balance gases from He to C3H8. Variation of the molecular weight of the balance gas resulted in the determination of O2 mass transport resistance due to Knudsen diffusion as well as diffusion and dissolution through liquid and ionomer films in a cathode catalyst layer (RK+film) and gas phase (Rm, N2). The application of a gas diffusion layer with and without a microporous layer (MPL) allowed us to separate contributions from the cathode catalyst layer (RK+film, CCL) and MPL (RMPL). The data demonstrated that RK+film, CCL significantly decreased from 92.36 to 52.83 s/m at 32 and 100% relative humidity, respectively, due to the effect of humidification on gas permeability through the ionomer. At the same time, Rm, N2 decreased slightly with gas humidification, while RMPL increased slightly. The results showed that fuel cell performance improved with a decrease in permeability mass transport overpotentials and RK+film, CCL. An analysis of the data demonstrated correlations between operating conditions, the mass transport parameters of the cathode gas diffusion electrodes, fuel cell performance, and voltage losses.

Numerical study of inhomogeneous deformation of gas diffusion layers on proton exchange membrane fuel cells performance

Gas diffusion layers play a critical role in the operation of proton exchange membrane fuel cells. As the most compressible component in proton exchange membrane fuel cells, the non-uniform deformation mainly occurs on the interface between bipolar plates and gas diffusion layers caused by the special channel-rib geometry of the flow field, which results in a non-uniform variation of physical properties of gas diffusion layers, such as porosity, effective electrical conductivity, and gas diffusivity, consequently affects the cell performance. In this paper, a two-dimensional, across-the-channel, multi-physics and two-phase flow model based on the spherical agglomerate assumption is developed to investigate the complicated relationships between the non-uniform deformation and variation of physical properties of the gas diffusion layers, as well as the cell performance. A modified diffusion coefficient is introduced to describe the effect of the variation of species concentration on the effective diffusion coefficient based on the Bruggeman formula. Simulation results show that an optimal cell performance can be achieved by balancing the variation of porosity, effective electrical conductivity, and effective gas diffusion coefficient with respect to different degrees of deformation of gas diffusion layers.

Study on proton exchange membrane fuel cells performance design: A case study of a small surface boat

The requirements for green energy have become more critical with the increasing risk from the global warming effect. In this study, previous study results were applied to obtain an optimal small surface boat configuration design and estimated its power requirement. The Proton Exchange Membrane Fuel Cells (PEMFC) are wildly used on vehicles. Its high working temperature (80 °C) make it a safer power source for small surface boat. This research used PEMFC as the test platform with test range from 0 to 2.4 kW. In order to obtain the optimum performance, Taguchi’s orthogonal array (L8 and L27) method was applied, with three factors: flow rate of hydrogen, humidification conditions, and temperature of the fuel cell stack, as the control parameters. According to the case study results, a dimensionless analysis were performed to acquire the ship model’s resistance–power curve and to evaluate the required power for a real ship (with a size that is three times that of the ship model). The speed was approximately 5 knots, and the required power was about 250 W. Finally, the best factor-level combination of Taguchi’s method is A2B3C2 and that the SNR is 57.81 dB. This is better than the value (approximately 0.43 dB) for the original design (A1B1C1). In addition, both the main effect and interaction of the three factors have significant influence, especially toward the fuel cell stack temperature. The robust design was obtained with the intelligence parameter method matching with the results of the Taguchi’s optimal prediction.

Modeling Anion Exchange Membrane Fuel Cell Performance and Its Stability: Validation, High-Temperature Operation and More

The increasingly high level of activity in Anion Exchange Membrane Fuel Cell (AEMFC) research and development over the past several years has included a strong component of computational modeling studies. While most of these have concentrated on various aspects of cell performance, our group's efforts are focused on the analysis of both performance and its stability [1,2]; in contrast with performance, the current state of the art of AEMFCs with respect to performance stability falls significantly short of what is required.In this contribution, we will describe our modeling approach which involves both 1-D and 3-D time dependent analyses of AEMFC operation. We account for mass transport, electrochemical phenomena, and ionomer degradation kinetics across the cell, involving a five-layer membrane electrode assembly. This includes a cathode gas diffusion layer (GDL), a cathode catalytic layer (CL), a membrane, an anode CL, and an anode GDL; in the case of 3D modeling gas flow channels are also included. Details of the models, associated simplifying assumptions and our numerical approach will be provided. This will be followed by the description of a number of sample studies.First, we will discuss validation via the comparison of cell performance and its stability against experimental data for different design and operating parameters. Next, we will present the application of our modeling approach in an effort to explore the effect of high-temperature operation on AEMFC performance and its stability. Our modeling results demonstrate the beneficial impact of using high operating temperature on AEMFC performance; this is attributed to better electrochemical kinetics, and reduced mass transfer limitations. Nontrivial benefits with respect to performance stability will also be demonstrated. Additional studies to be discussed include the analysis of Anion Exchange Ionomer (AEI) hydroxide conductivity and its impact on AEMFC performance and stability, as well as the analysis of performance using different gas flow channel geometries.

Synergistic Dual-Atom Molecular Catalyst Derived from Low-Temperature Pyrolyzed Heterobimetallic Macrocycle-N4 Corrole Complex for Oxygen Reduction.

A heterobimetallic corrole complex, comprising oxygen reduction reaction (ORR) active non-precious metals Co and Fe with a corrole-N4 center (PhFCC), is successfully synthesized and used to prepare a dual-atom molecular catalyst (DAMC) through subsequent low-temperature pyrolysis. This low-temperature pyrolyzed electrocatalyst exhibited impressive ORR performance, with onset potentials of 0.86 and 0.94V, and half-wave potentials of 0.75 and 0.85V, under acidic and basic conditions, respectively. During potential cycling, this DAMC displayed half-wave potential losses of only 25 and 5mV under acidic and alkaline conditions after 3000 cycles, respectively, demonstrating its excellent stability. Single-cell Nafion-based proton exchange membrane fuel cell performance using this DAMC as the cathode catalyst showed a maximum power density of 225mW cm-2 , almost close to that of most metal-N4 macrocycle-based catalysts. The present study showed that preservation of the defined CoN4 structure along with the cocatalytic Fe-Cx site synergistically acted as a dual ORR active center to boost overall ORR performance. The development of DAMC from a heterobimetallic CoN4-macrocyclic system using low-temperature pyrolysis is also advantageous for practical applications.

Construction and Application of Prediction Spectrum between PEMFC’s Performances and Ship Vibration

In order to analyze and evaluate the influence of ship vibration on the performance of proton exchange membrane fuel cell (PEMFC), firstly, the frequency domain and amplitude distribution characteristics of ship vibration are studied. Based on the general PEMFC simulation mathematical model, a boundary condition, loading method based on sliding grid technology (ZM-UDF) is proposed to establish the technical route of numerical simulation of PEMFC influence relationship on ship vibration performance. Secondly, in the full solution domain of ship vibration, a numerical simulation scheme is designed to study the influence of ship vibration direction, frequency and amplitude on the performance of proton exchange membrane fuel cell (PEMFC). Through simulation calculation, the performance database of ship vibration-proton exchange membrane fuel cell is constructed. Furthermore, the linear programming model of simulation data is established by using the difference- piecewise fitting method, and a prediction map construction method of ship vibration proton exchange membrane fuel cell performance characterization based on numerical simulation data is proposed. The performance prediction map of ship vibration proton exchange membrane fuel cell is drawn and verified by simulation.

Influence of Catalyst Layer and Gas Diffusion Layer Porosity in Proton Exchange Membrane Fuel Cell Performance

The current produced by the Proton Exchange Membrane Fuel cell (PEMFC) is dependent on the diffusion of the reactants through the cell components. In previous studies, the Gas Diffusion Layers (GDL) and catalyst porosities are considered as constant parameters. In this study, a Computational Fluid Dynamic (CFD) model in ANSYS FLUENT is used to simulate the fuel cell. Taguchi based optimization is done on the porosities of the GDL and catalyst layers in a single cell, and the performance of the cell is compared with a cell with uniform porosity at all the porous layers. It is found that the performance of the cell is enhanced by 12.5% by optimizing the porosities. Moreover, it is observed that the current density of a PEMFC intensely depends on the GDL porosity than the porosity of catalyst layers. Optimized porosity of the cell improves the membrane water content and ultimately results in better current density of the cell.

An integrated approach on proton exchange membrane fuel cell performance enhancement combining flower pollination algorithm and nanofluids

An integrated approach on proton exchange membrane fuel cell performance enhancement combining flower pollination algorithm and nanofluids

Effects of ratio variation in substrate and micro porous layer penetration on polymer exchange membrane fuel cell performance

A gas diffusion layer (GDL) facilitates the diffusion of reactant gas and the discharge of the generated water. The GDL performs various functions, such as conducting heat and electrons generated by electrochemical reactions and providing mechanical support for the catalyst layer. In this study, the effects of ratio variation in the substrate and microporous layer (MPL) penetration region on the proton exchange membrane fuel cell (PEMFC) performance were investigated. Furthermore, the reasons for these performance tendencies are explained based on the thermogravimetric analysis, contact angle, scanning electron microscopy, mercury porosimetry, electrical resistance, electrochemical impedance spectroscopy, and capillary pressure gradient. The experimental results indicate that the MPL penetration ratio within 15–20% of the total GDL thickness and the combined ratio of the MPL and MPL penetration within 35–40% is the best for the overall PEMFC performance. In addition, when the substrate ratio is excessively low, water flooding substantially occurs in the substrate, and this accumulated water functions as a back pressure, causing severe capillary condensation in the MPL penetration region and thus depriving the supply of the reactant gas.

A modified cathode catalyst layer with optimum electrode exposure for high current density and durable proton exchange membrane fuel cell operation

In proton exchange membrane fuel cells (PEMFCs), polymeric ionomer functions, as the membrane that transports protons and water from one electrode to another and as the catalyst binder and transport channel within the catalyst layer responsible for the electrochemical activity. Here, advanced membrane electrode assemblies (MEAs) of a hierarchical design having excellent durability and fuel cell performance that can be operated under low humidity is developed. The interaction of the pyrochlore Zr2Gd2O7 nanorod (ZrGdNR) with the ionomer used in both the electrolyte and catalyst layer enhances the oxygen reduction reaction and mass transport due to the multivalent property and oxygen vacancies. Open circuit voltage holding test and fluoride ion emission rate reveal the radical scavenger effect of ZrGdNR into the MEA to improve its durability. Compared to the conventional MEA, the modified MEA under 100 and 20% relative humidity delivers 1363 and 767 mW cm−2 of maximum power density, which is 1.8 and 6.3 times higher, respectively. The enormous increase in fuel cell performance and durability due to the 0.29 wt% of ZrGdNR with respect to Pt/C into the catalyst layer may be a promising approach for low catalyst usage in PEMFC having the ability to operate under low humidification.

Effect of Ionomer Content on FeNC Anion Exchange Membrane Fuel Cells Performance in Ambient Air Atmosphere

Effect of Ionomer Content on FeNC Anion Exchange Membrane Fuel Cells Performance in Ambient Air Atmosphere

SnO2 Nanoparticle Assisted Enhanced Proton Exchange Membrane Fuel Cell Performance of Sulfuric Acid-Doped Porous Poly (Triphenylpyridine–Aliphatic Ethers)

A proton exchange membrane fuel cell (PEMFC) was fabricated with SnO2 nanoparticles (NPs)-dispersed sulfuric acid-doped poly (triphenylpyridine aliphatic ether) (SPTPAEs) membrane and studied. The ...

Effect of Contamination towards Proton Exchange Membrane Fuel Cell Performance: A Review on Experimental and Numerical Works

Proton exchange membrane fuel cell (PEMFC) is a well-known energy converter that has low greenhouse gases (GHG) emission, low operating temperatures, and high power density. PEMFC operates on hydrogen (H2) as fuel, and oxygen (O2) as oxidant. Inverse electrolysis occurs between the oxidant and the fuel. Then, water (H2O) forms as their by product. Practically, O2 is supplied from the free air which contains not only oxygen but also other gases such as sulphur dioxide (SO2), and nitrogen oxides (NOx). Meanwhile, the H2 fuel may contain traces of carbon monoxide (CO) as a result from its previous reforming process. This makes PEMFC susceptible to disruption from these particles. These contaminating gases from the free air occupy the reacting sites originally meant for O2 and react with hydrogen ions instead of oxygen ions. While minute CO traces from the fuel occupies the reacting sites for H2 and react with oxygen ions instead of hydrogen ions. Consecutively, the energy output from the PEMFC will be short from its expected numerical value hence a less efficient PEMFC. Hence, this paper reviews recent research on PEMFC under the impact of cathode and anode side contaminants via experimental and numerical works. It is found that CO has more effect to the cell compared to CO2. SO2 and CO contaminates the catalyst layer while NOx does not. In addition, PtRu/C shows more resistance to contamination compared to traditional Pt/C. This comparative review serves to find out potentials in improving PEMFC operation and solving its mitigation strategies.

Exploring Anion Exchange Membrane Fuel Cell (AEMFC) Performance with Different Classes of Cathode Electrocatalysts

AEMFCs as an alternative to acidic polymer electrolyte fuel cells have the potential to reduce cost and precious metal requirements of fuel cell systems.1 In the past decade, several highly conductive polymers have been developed and a number of these have demonstrated more than 1W∙cm-2 peak power density with hundreds of hours stability; however, most of these studies have focused on Pt containing cathodes with high loadings.2,3 While the promise of Pt and Pt group metal (PGM) free electrocatalysis has been a major selling point of AEMFCs, more work exploring the potential of PGM-free cathode electrocatalysis is needed. In this study we explore and compare the performance of three leading cathode electrocatalysts: Pt/C, Ag/C, and Fe-N-C. These electrocatalysts are tested in AEMFCs cathodes using both powder- and dispersion-based PF AEM Gen 2 ionomers.4 The ability to test the different catalyst and ionomer combinations leads to additional insight into performance and catalyst-ionomer interactions.The performance trends of the tested MEAs will be presented. Pt/C has been found to be slightly superior to the performance of the non-Pt electrocatalysts. The performance of both metal nanoparticle catalysts, Pt/C and Ag/C, exhibit strong differences in performance depending on whether or not a powder or dispersion-based ionomer is used, with the powder-based approach showing much higher performance. Unlike the metal electrocatalysts, Fe-N-C catalysts show almost no change of performance between powder and dispersion-based ionomers.These performance metrics are also reflected in high frequency resistance measurements (Figure 1) investigated as a function of relative humidity at 300 mA·cm- 2. This data clearly shows the expected trend of increasing HFR with decreasing humidification of reactant gasses. The Fe-N-C data shows the lowest HFR values and very small changes between powder and dispersion-based ionomers. Both, Pt/C and Ag/C show dramatic increases in HFR for the dispersion-based polymer compared to the powder-based ionomer. These large changes in HFR are unexpected and cannot be fully explained just by changes happening within the electrodes. They suggest that not only do the electrodes undergo variable electrochemical properties due to this processing, but water management within the cell is also impacted by the type of catalyst and ionomer used in processing the electrodes. These features and the impact they have on the performance of different AEMFC cathodes will be presented and discussed.