Exchange Membrane Fuel Cell Performance Research Articles

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.

The influence of patterned microporous layer on the proton exchange membrane fuel cell performances

The influence of patterned microporous layer on the proton exchange membrane fuel cell performances

Performance evaluation of a blocked regulated lateral release channel for proton exchange membrane fuel cell based on entropy generation analysis

Oxygen-deficient regions at low voltage restrict the enhancement of proton exchange membrane fuel cell performance. To address this issue, a blocked regulated lateral release channel (BRLRC) is proposed to divert oxygen from blocked channel into oxygen-deficient areas. The implications of BRLRC on oxygen distribution, drainage capacity and output performance are investigated by adopting a three-dimensional multi-phase model. Through entropy generation analysis, multiple irreversible losses across varying locations for various flow fields are assessed. Structural optimization of BRLRC, focusing on parameters such as width, entrance, and junction positions of auxiliary channels, is conducted to boost net output power of the fuel cell. Results show that compared to the blocked channel, BRLRC further augments the output power, oxygen uniformity, drainage capacity and diminishes pump power. Analysis of cathodic entropy generation reveals that over 90% stems from mass transfer, with the catalyst layer as the main contributor, while BRLRC significantly reduces total entropy generation by mitigating mass transfer irreversibility. By accurately oxygen allocation, the structurally optimized BRLRC attains peak output power even with an oxygen concentration that is 7.5% lower than the maximal observed concentration. Building on this efficiency, when contrasted with the straight channel, BRLRC amplifies the maximum net output power by 9.04%, exceeding the 5.18% increase achieved by the conventional blocked channel.

Impact of Nonuniform Platinum Loading Distribution Design in the Catalyst Layer on the High-Temperature Proton Exchange Membrane Fuel Cell Performance

Impact of Nonuniform Platinum Loading Distribution Design in the Catalyst Layer on the High-Temperature Proton Exchange Membrane Fuel Cell Performance

Impact of Reinforced Polymer Electrolyte Membrane Scratch on Fuel Cell Durability Using 4D X-Ray Computed Tomography Technique

PEMFCs, or Polymer Electrolyte Membrane Fuel Cells, can be used in both stationary power and transportation applications and are promising for use in heavy duty electric vehicles due to their high energy density, ability to be refueled quickly, and extended range, which are key challenges for battery-powered vehicles [1]. Despite these advantages, there are still obstacles preventing the widespread commercialization of PEMFCs, one of which is production cost [2]. To reduce manufacturing costs, it is imperative to ensure that quality control rejects and scraps are minimized. Moreover, enhancing component integration defect detection would ensure the durability of the fuel cell and enhance its operational lifetime. However, robust quality control requires a thorough understanding of potential non-uniformities and their effects on fuel cell performance and operational degradation.Non-uniformities of the membrane electrolyte assembly (MEA) can result in durability issues by damaging the membrane and making it more vulnerable to mechanical and chemical stress during the operation [3]. Several studies have been done on cation contamination and membrane pinholes and their effect on fuel cell performance and durability [4,5] but little attention has been paid to other types of non-uniformities such as membrane scratches and foreign particles, which may also conceivably affect durability [6]. By implementing 4D in-situ X-ray computed tomography (XCT) [7,8], the current work aims to track the evolution of scratches that appear on a reinforced membrane surface during fabrication and its specific objective is to determine the impacts of membrane scratches on membrane durability in fuel cells.The study was conducted by using small-scale fuel cells with GORE-SELECT® membranes that were intentionally scratched with a razor blade, subjecting them to combined chemomechanical membrane accelerated stress test (AST), and monitoring the membrane degradation and evolution of the scratches using 4D-XCT throughout the AST. During the fabrication step, the depth of scratches was regulated by a weak bond between the reinforcement layer and the perfluorosulfonic acid (PFSA) layer, i.e., the scratches did not tear through the reinforcement. Furthermore, the scratches did not adversely impact the initial cell performance. However, during AST operation the evolution of the scratched region was affected by several factors, including the friction between the layers of the membrane electrode assembly, the width of the scratch (Figure 1), the presence of membrane debris, and the extent of membrane strain. Additionally, it was observed that changes in the quality of catalyst layer transfer onto the scratched region can alter the degradation pattern and potentially create a self-mitigating mechanism. These findings may be used to develop more optimized quality control measures for membrane scratches in fuel cell production. Acknowledgements This research was supported by the Natural Sciences and Engineering Research Council of Canada, Canada Foundation for Innovation, British Columbia Knowledge Development Fund, Western Economic Diversification Canada, Ballard Power Systems, and W.L. Gore & Associates. This research was undertaken, in part, thanks to funding from the Canada Research Chairs program. Keywords: fuel cell; membrane durability; X-ray computed tomography; membrane scratch; manufacturing References [1] Cullen DA, Neyerlin KC, Ahluwalia RK, Mukundan R, More KL, Borup RL, et al. New roads and challenges for fuel cells in heavy-duty transportation. Nat Energy 2021;6:462–74. https://doi.org/10.1038/s41560-021-00775-z.[2] Whiston MM, Azevedo IL, Litster S, Whitefoot KS, Samaras C, Whitacre JF. Expert assessments of the cost and expected future performance of proton exchange membrane fuel cells for vehicles. Proc Natl Acad Sci U S A 2019;116:4899–904.[3] De Bruijn FA, Dam VAT, Janssen GJM. Review: Durability and degradation issues of PEM fuel cell components. Fuel Cells 2008;8:3–22.[4] Tavassoli A, Lim C, Kolodziej J, Lauritzen M, Knights S, Wang GG, et al. Effect of catalyst layer defects on local membrane degradation in polymer electrolyte fuel cells. J Power Sources 2016;322:17–25.[5] Lü W, Liu Z, Wang C, Mao Z, Zhang M. The effects of pinholes on proton exchange membrane fuel cell performance. Int J Energy Res 2011;35:24–30.[6] Kundu S, Fowler MW, Simon LC, Grot S. Morphological features (defects) in fuel cell membrane electrode assemblies. J Power Sources 2006;157:650–6.[7] Ramani D, Singh Y, White RT, Wegener M, Orfino FP, Dutta M, et al. 4D in situ visualization of mechanical degradation evolution in reinforced fuel cell membranes. Int J Hydrogen Energy 2020;45:10089–103.[8] White RT, Eberhardt SH, Singh Y, Haddow T, Dutta M, Orfino FP, et al. Four-dimensional joint visualization of electrode degradation and liquid water distribution inside operating polymer electrolyte fuel cells. Sci Rep 2019;9:1–12. Figure 1

Efficient health indicators for the prediction of the remaining useful life of proton exchange membrane fuel cells

Proton Exchange Membrane Fuel Cells (PEMFCs) are devices that convert hydrogen into energy through a chemical process called electrolysis. They hold promise in reducing the harmful environmental effects of fossil fuels and could potentially replace current energy systems in the near future if certain challenges are overcome. One major challenge in Proton Exchange Membrane Fuel Cell (PEMFC) performance is its durability. This issue, although common in many industrial assets, holds even more significance in PEMFCs due to their high costs and the need for reliable operation. Predictive Maintenance (PM), as a part of Prognostic and Health Management (PHM), focuses on addressing the durability problem by predicting the Remaining Useful Life (RUL) of PEMFCs. In this study, machine learning was used to predict the RUL of a stack of five PEMFCs operating under both static and quasi-dynamic conditions, resulting in two distinct datasets. Multiple health indicators were tested by combining domain expertise and the characteristics of PEMFC data to estimate the RUL.The results reveal that the power-time fraction health indicator accurately predicted the RUL in the static regime with an impressive R2 value of 99% and an RMSE error of 4.59e-07, using the random forest regressor. This analysis was also extended to the quasidynamic regime for validation, achieving an R2 of 95% and an RMSE of 0.06, which demonstrates the strong potential of this health indicator. Additionally, Explainable AI was employed for the first time in this context to enhance the transparency of the results. This work serves as an excellent starting point for further exploration of new health indicators and highlights the power of machine learning in addressing the crucial issue of predicting the RUL of PEMFCs.

Experimental evaluation of proton exchange membrane fuel cell performance with sinusoidal flow channel designs

Proton Exchange Membrane Fuel Cells (PEMFCs) with three distinct flow field designs were investigated: sinusoidal with a diffuser at the intake, sinusoidal serpentine, and serpentine flow fields. The sinusoidal flow field with a diffuser at the intake has been found to be the best flow field design. Following that, parametric experiments were performed on PEMFCs equipped with a sinusoidal flow field with a diffuser at the intake. Operating pressures (1–3 bar), back pressures (0–3 bar), anode humidification temperatures (40 °C–80 °C), cathode humidification temperatures (40 °C–70 °C), anode flow rates (250 sccm to 350 sccm) and cathode flow rates (250 sccm to 400 sccm) and cell operating temperatures (COT) ranging from 40 °C to 70 °C were all adjusted. The experimental findings showed that a COT of 60 °C, a 3-bar back pressure, a 3-bar working pressure, cathode humidification at 70 °C, anode humidification at 60 °C, and flow rates of 300 sccm for the anode and 350 sccm for the cathode resulted in the best PEMFC performance.

Multi-objective optimization of gradient gas diffusion layer structures for enhancing proton exchange membrane fuel cell performance based on response surface methodology and non-dominated sorting genetic algorithm-III

The gas diffusion layer structure has a significant impact on water and gas transport in proton exchange membrane fuel cell (PEMFC). In this study, a multi-objective optimization (MOO) method is applied to optimize the PEMFC gas diffusion layer (GDL) structures for performance enhancement. Nine design parameters are studied to analyses the output performance of the fuel cell and the average water content of the membrane, oxygen concentration non-uniformity, power density and system efficiency are used as performance indexes. The MOO forms the response surface regression model based on the three-dimensional numerical model of PEMFC, and the response surface methodology after processing through the non-dominated sorting genetic algorithm-III (NSGA-III) to obtain the Pareto frontier, and prioritizes the best operating conditions and structures based on technique for order preference by similarity to an ideal solution (TOPSIS). Compared with the reference point, the performance indexes of the decision point obtained by the NSGA-III algorithm and TOPSIS algorithm is enhanced by 0.45 %, 42.06 %, 2.99 % and 0.25 %, respectively. This study presents a new multi-objective optimization method for optimizing operating conditions combine with GDL structures for building efficient PEMFC, which provides a solution for achieving higher performance. The optimal results in this paper can provide some guidance for fuel cell performance improvement and control optimization.

Effects of Different Channel Geometries of Metallic Bipolar Plates on Proton Exchange Membrane Fuel Cell Performance

This paper investigates the effects of different channel geometries on the performance of Proton Exchange Membrane Fuel Cells (PEMFCs). The study employs computational fluid dynamics (CFD) coupled with thermal and electrochemical simulations to analyze five channel geometries (cases A to E) of bipolar plates. A thorough study on this topic is not found in the literature and aims to identify designs that optimize performance and align with cost-effective production methods. Among the various studied geometries, case D, featuring a trapezoidal cross-section, exhibited the most favorable performance compared to the others, with a current density value of 2.01 A/cm2 and a maximum temperature of 74.89 °C at 0.3 V, leading to an increase in generated power of 4.46%, compared to base case A. The trapezoidal shape enhanced the contact area with the reacting region, resulting in higher reaction rates and an improved overall performance. However, the study also highlights the relevance of velocity and turbulence, with case B demonstrating an enhanced performance due to its higher velocity, and case E benefiting from localized higher velocity regions and turbulence created by baffles. Case B can increase generated power at its peak by around 3.21%, and case E can improve it by 1.29%, with respect to case A. These findings underscore that contact area has a major impact on the PEMFC performance, but velocity and turbulence also play relevant roles. Additionally, trapezoidal channels can be easily manufactured through sheet metal-forming techniques, aligning well with new market trends of weight and cost reduction on bipolar plates. Fuel and oxygen utilization percentages, 38.14% and 62.96% at 0.3 V, respectively, further confirm the superiority of trapezoidal channels, providing insights into optimizing the PEMFC performance. This exhaustive study contributes valuable information for designing efficient metallic bipolar plates and advancing the development of practical fuel cell technologies.

Numerical study of Tesla valve flow field on proton exchange membrane fuel cell performance

Effective flow channels in proton exchange membrane fuel cells (PEMFCs) can provide sufficient reactant and a more uniform reactant distribution, which allows the fuel cells to operate with high performances. The Tesla valve structure is thought to be a feasible structure for channel design due to its one-directional flow characteristics, yielding different performances with different flow directions. Numerical studies were conducted in this work to investigate the impacts of the channel structure, flow direction, and excess air coefficient on the fuel cell performance. Three types of flow channels (straight, symmetric Tesla valve, and asymmetric Tesla valve) and two flow directions (forward and reverse) were studied. The results showed that the maximum power density of the reversed asymmetric Tesla valve increased by 10.08 % compared to that of the conventional straight channel. Detailed research revealed that the Tesla valve resulted in a more intense flow than the conventional straight channel. The symmetric Tesla valve resulted in a greater pressure drop than the asymmetric valve. The Tesla valves with reverse flow could significantly limit the formation of an oxygen dead zone. Hence, enhanced Z-direction mass transfer and the lowest standard deviations of the oxygen and water distributions were observed. The effects of the excess air coefficient on the net power density were also studied. Increasing the excess air mass to the cathode facilitated the enhancement of the electrode voltage but required more parasitic power due to the growth in the pressure drop along the flow channel.

Data-based modelling of proton exchange membrane fuel cell performance and degradation dynamics

Proton exchange membrane fuel cell (PEMFC) is in the commercial adoption process for hard-to-decarbonize applications such as transport. However, its long-term durability, reliability, diagnostics, and performance remain a critical challenge. In this study, the data-based modelling technique, artificial neural network (ANN), is adopted to comprehend performance degradation and thermal and pressure dynamics. Experimental data consisting of polarization and cyclic voltammetry data are acquired after every 6,000 accelerated stress test (AST) degradation cycles as stipulated by the US Department of Energy guidelines. Over 40,000 test cases were considered for training and evaluating the neural network comprising data from 30,000 full-cell AST cycles. Fuel cell operating temperatures, pressures, flow rates, and relative humidities are varied to capture the entire spectrum of PEMFC performance characteristics. Parameters such as the number of AST cycles endured or instantaneous catalyst electrode surface area, operating current density, reactant flow rate, relative humidity, system temperature and pressure are considered as feature vectors (inputs) to predict cell output voltage, reactant outlet pressure and temperature for both anode and cathode streams. Data preprocessing and batch learning are implemented in Python to improve prediction accuracy and computational time; considering the substantial nonlinear data sets, various Keras library optimizers and corresponding hyperparameters are investigated for better convergence. The trained neural network model is evaluated on 15,000 test cases resulting in an R2 ≥ 0.995 for all the predicted variables, demonstrating the capability of data-based models to accurately predict the nonlinear behavior of such electrochemical systems with minimal processing time, advocating for their application in real-time system monitoring, controls and diagnostics.

Effects of cathode gas channel design on air-cooled proton exchange membrane fuel cell performance

In the study, the impact of cathode gas channel (CGC) structure on the operation of air-cooled PEMFCs is investigated by a multiphase nonisothermal model. First, the influences of tapered channel configuration on the distribution of key variable distributions are studied. The distributions of these variables are found to be coupled with the reactive transport process within the catalyst layer (CL). The variation of local current density is found to be positively correlated with the dissolved water content. Although the tapered channel design can improve the current density, the weight of the bipolar plates (BPs) will be inevitably increased. Finally, the trapezoidal channel design is proposed aiming at improving the performance without increase of fuel cell weight. Several performance indexes are employed to comprehensively evaluate the different CGC designs, and the results demonstrate that the inverted trapezoidal CGC design, with which good thermal and water management are achieved, presents the best performance among the different CGC designs studied, leading to 18.9 % increase of the mass power density and 18.6 % increase of volume power density compared with the base case design.

Mechanical response of carbon paper gas diffusion layer under patterned compression

The Proton Exchange Membrane Fuel Cell (PEMFC) performances are strongly impacted by the compression of the Gas Diffusion Layer (GDL). Despite its fibrous microstructure, this material is usually considered as a continuous medium and characterized with uniform loading. However, the GDL is subjected to a heterogeneous compression onto rib/channel patterns in the fuel cell assembly. In the present study, a complex behavior of the GDL response is experimentally revealed when the material is loaded with a rib/channel pattern, compared to uniform compression. The tests are simulated by finite element modeling using a classical strain-dependent elastic law, using parameters fitted from uniform compression experiments. It is shown that the numerical results do not reproduce the effect of pattern observed experimentally. Hypotheses to interpret these results involve mechanisms at the fiber microscale including fiber fracture, cross-link breakage and fiber rearrangement, which are exacerbated by larger material deformation caused by the heterogeneous loading.

Single‐atom Pt on carbon nanotubes for selective electrocatalysis

AbstractUtilizing supported single atoms as catalysts presents an opportunity to reduce the usage of critical raw materials such as platinum, which are essential for electrochemical reactions such as hydrogen oxidation reaction (HOR). Herein, we describe the synthesis of a Pt single electrocatalyst inside single‐walled carbon nanotubes (SWCNTs) via a redox reaction. Characterizations via electron microscopy, X‐ray photoelectron microscopy, and X‐ray absorption spectroscopy show the single‐atom nature of the Pt. The electrochemical behavior of the sample to hydrogen and oxygen was investigated using the advanced floating electrode technique, which minimizes mass transport limitations and gives a thorough insight into the activity of the electrocatalyst. The single‐atom samples showed higher HOR activity than state‐of‐the‐art 30% Pt/C while almost no oxygen reduction reaction activity in the proton exchange membrane fuel cell operating range. The selective activity toward HOR arose as the main fingerprint of the catalyst confinement in the SWCNTs.

Multi-objective optimization of a double tapered flow field Proton Exchange Membrane Fuel cell

Flow fields are essential in Proton Exchange Membrane Fuel Cell (PEMFC) performance. Appropriate in-plane tapering in the main channels width of parallel flow fields enhances flow distribution uniformity, increasing performance. To the best of the authors, there is no literature discussing the through-plane inclination in a parallel flow field with in-plane tapered main channels. This study develops a surrogate model based on a data set to study double tapering in the flow field. The three-dimensional multiphase Computational Fluid Dynamics (CFD) generates the data set. Decision variables are the angle of depth tapering, operating pressure, temperature, stoichiometries, and voltage. Also, the objectives are power density and efficiency. Proper depth tapering increases mass transfer, decreasing the concentration loss. The increment of 19.6% in maximum power is captured by tapering. Depth tapering in the parallel flow field improves efficiency, especially at a higher temperature and lower pressure. Furthermore, a multi-layer multi-objective optimization methods are utilized. A reference depth tapering angle θ is defined. Optimum characteristics are the tapering angle of 0.13θ, the temperature of 329.9 K, the operating pressure of 4 atm, the operating voltage of 0.465 V, and the unit stoichiometry of both sides. Optimum characteristics bring the best performance, an efficiency of 21.55%, and a power density of 0.75 W cm−2.

Operando investigations of proton exchange membrane fuel cells performance during air interruptions in dry and humidified conditions

Activating proton exchange membrane fuel cells is crucial to systematically build proton conductive pathways, remove contaminants from the electrode surface and obtain the highest performances, with air interruption emerging as one of the most powerful methods. While this approach enables fast activation and considerable recovery after extended periods of shutdown or operation, the impact of relative humidity on this process has not been explored. Herein, the impact of the relative humidity on the air interruption is investigated using an array of operando methods such as polarization, electrochemical impedance spectroscopy, and high-resolution localized current and mapping. It is found that while air interruptions in humidified conditions can improve performance, they rapidly reduce them in dry conditions. Specifically, air interruptions in fully humidified conditions improve ions, charges, and gas diffusion to the active sites, which may be attributed to the removal of platinum oxides increasing active site availability. However, air interruptions under low relative humidity rapidly reduce the cell voltage by increasing charge transfer and mass transport limitations, while causing extensive overheating as the cell is starved of oxygen and hydrogen might be generated. Overall, this work reveals the potential, yet limitations of air interruptions in operando hydrogen fuel cells.

A Super Uniform Hydrophobic Gas Diffusion Layer for a Proton Exchange Membrane Fuel Cell.

The design and optimization of the gas diffusion layer (GDL) play a crucial role in the improvement of proton exchange membrane fuel cell performance. Hydrophobic treatment of a GDL is an important method for facilitating mass transfer, while conventional Teflon treatment is not uniform and leads to an increase in ohmic and heat resistance. Herein, a homogeneous molecular hydrophobic GDL was prepared by liquid phase synthesis, and a two-dimensional non-isothermal model was developed to investigate the transfer mechanism. The peak power density of cells with the GDL described above was improved by 46% compared to that of the conventional GDL. The ohmic and mass transport resistance decreased by 15% and 52%, respectively, under a current density of 1 A cm-2 using the uniform hydrophobic GDL. The simulation results proved that the uniform hydrophobic GDL eliminates the hydrophilic dots, which prevents the formation of water pools and reduces the resistance to gas flow. The water saturation of the conventional GDL reaches 0.19 at a current density of 1 A cm-2, and the saturation of a modified GDL under the same conditions is only 0.13. A dimensionless parameter, Tf, is proposed to characterize the resistance of oxygen diffusion. In conclusion, molecular-level uniform hydrophobic treatment can effectively reduce the ohmic and mass transfer resistance of a GDL and effectively improve the performance of fuel cells.

Enhancing durability of polymer electrolyte membrane using cation size selective agents

Radical species generated during proton exchange membrane fuel cell operation considerably limit the achievable durability, particularly for heavy-duty vehicle applications. A promising solution to the problem is the incorporation of radical scavenger additives such as cerium which mitigates chemical attacks on the membrane. However, these additives migrate during fuel cell operation causing a loss in durability and performance due to detrimental interaction with various components of the fuel cell. Here, we study cation size selective agents as a means to immobilize cerium within perfluorosulfonic acid (PFSA) membranes. We synthesized an organometallic complex of cerium with 15-Crown-5 and investigated the effectiveness of this complex to immobilize cerium. Over 300% increase in cerium retention and an 80% increase in chemical durability were observed owing to the stabilization effect of crown ethers on cerium. Migration under a potential gradient can be eliminated while the complex also contributes to the enhancement in cerium radical scavenging activity. Current challenges with the proposed solution are highlighted and future work is discussed.

Numerical Simulation of the Effect of Heat Conductivity on Proton Exchange Membrane Fuel Cell Performance in Different Axis Directions

In this paper, the effect of changes in the thermal conductivity of porous electrodes in three coordinate directions on the capability of proton exchange membrane fuel cells is investigated on the basis of current density versus voltammetry curves, and the temperature distribution and water-carrying capacity distribution of the membrane. The results show that when the cell discharge voltage of the PEMFC is 0.3 V, the thermal conductivity in the Z-direction of the porous electrode has a greater effect on the performance of the PEMFC than in the other directions, with the thermal conductivity in the X- and Y-directions of the porous electrode having less than a 5% effect on the performance of the PEMFC, which can therefore be neglected. When the thermal conductivity of the porous electrode in the Z-direction of the PEMFC is 500 W/(m·K) and 1000 W/(m·K), the performance of the PEMFC is improved by 5.78% and 5.87%, respectively, and when the thermal conductivity of the porous electrode in the X-direction of the PEMFC is 500 W/(m·K) and 1000 W/(m·K), the performance of the PEMFC is improved by 2.09% and 2.89%, and the PEMFC performance is improved by 1.51% and 2.00% when the Y-direction thermal conductivity of the porous electrode of the PEMFC is 500 W/(m·K) and 1000 W/(m·K), respectively. The improvement in performance decreases with increasing thermal conductivity, because the thickness of the porous electrode is too thin. Since the side of the model is set to adiabatic heat exchange conditions, while the top and bottom surfaces are set to natural convection heat exchange conditions, the Z-direction thermal conductivity of the porous electrode plays the most important role in the temperature distribution of the PEMFC. The Z-direction thermal conductivity of the porous electrode causes the temperature distribution of the PEMFC assembly to be more uniform, and the Z-direction thermal conductivity of the porous electrode also causes the area of the high-water-content region on the proton exchange membrane to significantly increase.

Effect of cathode catalyst layer on proton exchange membrane fuel cell performance: Considering the spatially variable distribution

The effect of the ionomer spatial distribution in the cathode catalyst layer (CCL) of the proton exchange membrane fuel cell (PEMFC) on oxygen and proton transport has been extensively studied. However, models generally assume a mean spatial distribution (MSD) of ionomer, and consideration of the actual spatial distribution (ASD) is indeed insufficient. In this study, a multi-dimensional PEMFC model is developed to investigate the effect of ionomer ASD versus MSD on cell performance. In addition, we corrected the Damkohler number (Da) by taking into account the local oxygen transport interfacial resistance and catalyst parameters into δ (an effective ionomer thickness), which allows Da to more accurately reflect the oxygen supply. The results show that the MSD assumption for ionomer tends to underestimate cell performance at the same current density. The proton transport resistance of ASD is 3.17% higher than that of MSD, but the oxygen concentration is 42.8% larger. This is mainly attributed to the larger porosity and lower saturation near the CCL/CMPL interface in the ASD model, which facilitates oxygen transport. The Da sufficiently supports the results, and the Da at the CCL/MPL interface of the ASD model (0.34) is smaller than in the MSD model (0.82), indicating relative oxygen enrichment. This study provides guidance for future PEMFC models.