Uniformity Of Current Density Research Articles

Deep learning assisted anode porous transport layer inverse design for proton exchange membrane water electrolysis

Proton exchange membrane water electrolysis cell (PEMEC) offers a clean and promising way for hydrogen production. The spatial internal current density and temperature distribution uniformity significantly determines its reliability and durability, as well as the hydrogen production performance. Here, a non-isothermal 3D computational fluid dynamics (CFD) model for PEMEC with parallel flow fields is employed to investigate the impacts of the heterogeneous porosity distribution within the anode porous transport layer (APTL) on the internal current density and temperature distribution uniformity and energy conversion performance. 800 heterogeneous APTL porosity distributions are applied for CFD calculation, providing dataset for deep learning. The deep operator network (DeepONet) is employed to mapping the heterogeneous APTL porosity distribution to the real physical fields such as temperature, oxygen molar fraction and current density distribution fields. Full-connected neural network is employed to construct the relationship between the heterogeneous APTL porosity distribution to the performance metrics. The gradient descent algorithm is applied to obtain APTL porosity distributions corresponding to the optimal internal current density and temperature distribution uniformity, respectively. Compared with the uniform porosity distribution, the current density and temperature uniformity are improved by 45.544 % and 26.680 %, respectively, at an average APTL porosity of 0.5.

Analyzing Key Factors Influencing Water Transport in Open Air-Cooled PEM Fuel Cells.

The current limitations of air-cooled proton exchange membrane fuel cells (AC-PEMFCs) in water and heat management remain a major obstacle to their commercialization. A 90 cm2 full-size AC-PEMFC multi-physical field-coupled numerical model was constructed; isothermal and non-isothermal calculations were performed to explore the effects of univariate and multivariate variables on cell performance, respectively. The isothermal results indicate that lower temperature is beneficial to increase the humidity of MEA, and distribution uniformity at lower stoichiometric ratios and lower temperatures is better. The correlation between current density distribution and temperature, water content, and concentration distribution shows that the performance of AC-PEMFCs is influenced by multiple factors. Notably, under high current operation, the large heat generation may lead to high local temperature and performance decline, especially in the under-channel region with drier MEA. The higher stoichiometric ratio can enhance heat dissipation, improve the uniformity of current density, and increase power density. Optimal fuel cell performance is achieved with a stoichiometric ratio of 300, balancing the mixed influence of multiple factors.

Optimization and Testing of DC Electromagnetic Pump for Liquid Metal Space Use

Driving a liquid metal via an electromagnetic pump (EMP) is becoming increasingly important with its many emerging cutting-edge uses. The end losses associated with the EMP generally play a core role in dominating device performance. In this study, we explored the effects of electrode width, number of insulating strips, and pump width on the end loss through theoretical analysis and numerical simulations. The optimization results indicate that reducing electrode width would improve EMP performance. Adding insulation strips enhances the magnitude and uniformity of effective current density but raises hydraulic losses. A smaller pump width achieves a stronger static head, while a larger pump width outputs a higher flow rate. Furthermore, 3D printing technology was employed for rapid integrated processing of the pump body. Detailed performance evaluations and reliability tests were carried out on the EMP. With the design optimized so as to minimize the end losses, an EMP for space experiments has been successfully developed, which will eventually be flown on the China’s space station. Overall, the feasibility of fast, low-cost manufacturing of high-reliability, compact EMP with the assistance of numerical simulation and 3D printing technology was demonstrated. It provides an alternative option for driving metallic fluid for various future space needs.

A comprehensive 3D modelling exploration of a protonic ceramic electrolysis cell stack with metal foam

Protonic ceramic electrolysis cells (PCECs) offer significant potential for large-scale green hydrogen production. The performance of conventional PCEC stacks is notably limited due to the uneven gas distribution. In this research, a new stack design using metal foam as the gas distributor is proposed and numerically evaluated using a 3D Multiphysics model to improve the gas distribution uniformity. At 1.3 V and 600 °C, the current density of the newly designed PCEC with metal foam is 173 % higher than that of the conventional PCEC. Moreover, the hydrogen production capability of metal foam based PCEC is 234 % higher than that of conventional PCEC, due to the improved gas distribution uniformity and faradaic efficiency (FE) of the new PCEC. The application of metal foam increases steam distribution uniformity by 91.2 %. In a conventional PCEC, the FE under the rib is notably lower than that under the channel. In contrast, the FE distribution is more uniform in a metal foam based PCEC. The improved performance in terms of current density, FE, and distribution uniformity highlights the potential of metal foam as a beneficial component in PCEC stacks. These findings contribute to the understanding and further development of PCEC technology.

Numerical investigation of parameter distributions in high-temperature PEMFCs under various cooling surface temperature gradients

Non-uniform current density distribution can lead to localized hotspots, resulting in shortened lifespans of fuel cells. The temperature distributions on the bipolar plate cooling surface significantly influence various parameters within a fuel cell. This study develops a mathematical model for a high-temperature proton exchange membrane fuel cell (HT-PEMFC) to simulate its operation in four different directions of temperature gradient on the cooling surface. The distributions of membrane temperature, proton conductivity, oxygen concentration, activation loss, and current density were obtained to clarify the interaction mechanism between cooling surface temperature and these parameters in fuel cell. The results show that the membrane temperature and proton conductivity increase and the oxygen concentrations decrease with increasing cooling surface temperature. A lower temperature in the catalyst layer regions leads to a decrease in the current density. In particular, when the cooling surface temperature distribution is characterized by a temperature decrease in the upstream area with a high reactant concentration and an increase in the downstream area with a low reactant concentration, the fuel cell has an excellent current density uniformity, which reaches 92.61 % at a voltage of 0.6 V and a cooling surface temperature difference of 10 K.

Airfoil flow field for proton exchange membrane fuel cells enhancing mass transfer with low pressure drop

Optimal configuration of bipolar plate (BP) embedding flow field is of great significance in improving the power density and durability of proton exchange membrane fuel cells (PEMFCs). Inspired by the airfoil in aircraft dividing the airflow into two streams causing pressure difference, a novel airfoil flow field (AFF) is designed to enhance the mass transfer capacity in channel and across the rib between two adjacent channels, which hardly increases the pressure drop in channel, unlike many baffle designs. The performance improvement achieved by implementing AFF in PEMFC is compared with common parallel flow field (PFF) and the wave flow field (WFF) by experimental test with respect to polarization curve and electrochemical loss and numerical simulation via a three-dimensional (3D) PEMFC model. The experimental results indicate that the novel AFF exhibits best fuel cell performance at various operation conditions (e.g. relative humidity, air stoichiometric ratio) mainly benefitted from the enhanced oxygen transfer, which contributes to the improvement of maximum power density by 8.85 % and 14.37 % compared to PFF and WFF, respectively. The modeling results indicate that the pressure drop increase in AFF is negligible compared with PFF, and is even slightly lower than WFF, indicating high practicability. Moreover, the utilization of AFF also helps the uniformity of oxygen concentration, current density and temperature in PEMFC.

Dynamic internal performance of PEMFC under fuel starvation with high-resolution current mapping: An experimental study

The fuel starvation in a proton exchange membrane fuel cell (PEMFC) during automotive operation conditions could lead to severe decay of the catalyst layer and performance degradation. As the fuel starvation occurs locally and induces uneven reverse current inside the fuel cell stack, it is critical to understand the dynamic mechanism of the fuel cell internal performance during the fuel starvation process. In this work, a self-developed segmented cell with 396 segments is applied to measure the transient current distributions inside the fuel cell stack with active area of 406 cm2. In the present experiment, the fuel starvation process is simulated by decreasing the H2 stoichiometric ratio from 1.5 to 1.0 and the dynamic performance is tested as the cell voltage drops to the shutdown values. The results show that the current density uniformity worsens significantly during the fuel starvation, even though the load current is kept stable. With the cell voltage decreasing from 0.5 V to −0.9 V in fuel starvation, the maximum local current around H2 inlet rises from 1.363 A/cm2 to 3.697 A/cm2 and the lowest current density near H2 outlet drops from −0.039 A/cm2 to −0.1 A/cm2 under the load current density of 0.5 A/cm2. The analysis of transient local current behaviors corresponding to the voltage reversal process is beneficial to optimize the control of PEMFC system and mitigate the performance degradation.

Multi-objective optimization of water electrolysis based on coupling model of electrochemistry and multiphase flow

In this paper, a coupling model of electrochemistry and multiphase flow is established, which considers the interaction between electrochemical reactions and the flow regime of gas and liquid. Based on the ANOVA analysis, response surface methodology, and multi-objective optimization, the effects of electrolyte temperature, electrolyte concentration, and inlet velocity on the performance of water electrolysis are further studied. The calculation results show that with the increase of temperature and concentration of electrolyte, the average value of current density gradually increases, but the uniformity of current density and the specific energy consumption will deteriorate. Increasing the inlet velocity can simultaneously improve the average value and the uniformity of current density and specific energy consumption. And the intelligent optimization algorithm is introduced into the field of water electrolysis to obtain the local sensitivity and the Pareto front. Three groups of optimized parameters are determined. Compared with the original parameters, the average value of the current density of the optimized parameters increases by 7.04 % on average, the variance of the current density of that decreases by 28.14 % on average, and the specific energy consumption of the optimized parameters reduces by 45.90 % on average. The empirical correlation between operating parameters and electrolyzer performance is obtained. The research results provide guidance for the design of electrolyzer.

Multi-flow channel proton exchange membrane fuel cell mass transfer and performance analysis

This paper presents a study on the proton exchange membrane fuel cell (PEMFC) with a high humidity three-dimensional two-phase multi-channel model using COMSOL. The effects of gradient porosity in the gas diffusion layer (GDL) and gradient electrolyte volume fraction in the catalyst layer (CL) in the Y-direction on oxygen distribution, liquid water removal, current density surface area reaction rate (SCS), and current density magnitude of PEMFC are investigated. The results indicate that an appropriate gradient porosity in the GDL can improve the performance of PEMFC, especially in terms of oxygen distribution. Similarly, an appropriate gradient electrolyte volume fraction in the CL can enhance the current density uniformity. In addition, an improved multi-objective genetic optimization algorithm (RONSGA-II) is proposed in Chapter 4, along with an optimization method based on neural networks and RONSGA-II. As an example, the gradient porosity in the GDL in the Y-direction is optimized for current density and water removal. The optimized current density is increased by 1.22%, and water removal performance is improved by 16.67%.

Multi-objective optimization of PEMFC performance based on grey correlation analysis and response surface method

This paper aims to combine grey correlation analysis and response surface method to propose a fast and effective performance optimization method for PEMFC. First, based on orthogonal test data, grey correlation analysis method is used to select four variables that have significant influence on PEMFC’s comprehensive performance from eight common parameters. Secondly, based on grey correlation analysis, the multi-objective optimization problem is transformed into a single objective optimization problem about correlation degree, and applying the response surface method to build the key parameters and the correlation between the second order prediction model. Therefore, the current density, system efficiency and oxygen distribution uniformity on cathode catalyst layer of PEMFC were optimized as a whole. Finally, the optimal parameter combination was obtained by optimizing the prediction model. The simulation results show that the optimized operating conditions are significantly improved in the three performance indexes compared with the basic model, which confirms the feasibility of this method in solving the multi-objective optimization problem, and can provide some reference for the optimal design of hydrogen fuel cells.

Numerical study on performance of HT-PEMFC with gradient design of Pt loading

In this paper, the spatial distribution of overpotential and current density of high temperature proton exchange membrane fuel cell (HT-PEMFC) with gradient design of platinum (Pt) loading is studied. Three Pt loading gradient distributions are considered: along the thickness direction of the catalyst layer (CL), along the flow direction and the bidirectional linear gradient distribution. The results show that the increase of the Pt loading near the membrane could improve the fuel cell performance and catalyst utilization when the total amount of Pt in CL consistent. In addition, the increase of Pt loading along the flow direction provides a more uniform current density for the fuel cell, but lower cell performance. The bidirectional linear gradient distribution of Pt loading is studied, and the results show that the current density distribution is more uniform, but the cell performance is slightly improved. Therefore, the results demonstrate that the reasonable distribution of Pt loading can improve the cell performance and improve the uniformity of current density, which is of great significance to improve the utilization of catalyst.

Elucidating the sensitivity to key operating parameters of a commercial-scale solid oxide fuel cell stack with open cathode manifolds

Solid oxide fuel cell (SOFC) is considered a promising eco-friendly energy conversion technology due to its high efficiency and fuel flexibility resulting from its high-temperature operation and ceramic structure. However, nonuniformities in thermal and electrochemical distribution within the SOFC stack can lead to performance degradation and hinder its market competitiveness. This study aims to identify optimal operating conditions to minimize these nonuniformities by investigating the effects of key operating conditions on the internal phenomena and local thermodynamic states of a commercial-scale stack. A highly reliable hydrocarbon-fueled SOFC model is developed and used to investigate the response of a 1-kW commercial-scale stack with open cathode manifolds to changes in key operating conditions. A parametric study is conducted on the air inlet temperature, air utilization, external reforming rate, and operating current density. Results show that increasing the air inlet temperature improves the uniformity of in-plane temperature distribution but deteriorates the uniformity of current density distribution. Air utilization and air inlet temperature have an identical mechanism to alter the internal distribution, thus showing a similar effect on local thermodynamic states. However, when altering the air utilization, the rate of decrease in uniformity of vertical temperature and current density is 5.39 times and 2.47 times larger than the change in the air inlet temperature. Increasing the external reforming rate exacerbates the overall distribution of local thermodynamic states. Among the selected operating parameters, the operating current density has the greatest influence on the in-plane temperature and current density distribution. This study provides guidance on the desired internal conditions inside the stack by quantitatively analyzing the effects of key operating conditions on the internal phenomena and local thermodynamic states of the stack through performance parameters and sensitivity analysis.

Optimal and modeling study of air-cooled proton exchange membrane fuel cell with various length-width ratio and numbers

Air-cooled proton exchange membrane fuel cell is a positive and effective energy strategy to improve the efficiency of applications in robots and unmanned aerial vehicles. In this paper, novel air-cooled proton exchange membrane fuel cells based on different length-width ratio (RL/W) of the cell and the number of anode serpentine are designed to explore their effects on oxygen mass fraction distribution, temperature distribution, pressure drop, as well as the cell performance. The results show that RL/W has outstanding impact on the performance, and the uniformity of current density, oxygen mass fraction, temperature and water distribution can be improved by increasing RL/W, so as to obtain better performance. Increasing the amount of anode serpentine channels also has positive effect. While when RL/W is small, the number of anode flow channels has a greater impact on the performance and parameter distribution than the RL/W of the bipolar plate. When RL/W is greater than 2.94, the performance mainly depends on RL/W. This research provides basic data that is significant for the system optimization and application of air-cooled proton exchange membrane fuel cells in the future.

Uniformization of a large beam spot using sextupole magnets for a compact multiple-energy electron accelerator

We have commissioned a multiple-energy electron accelerator that illuminates an 800 mm × 800 mm target. The energy of the beam ranges from 0.5 to 5 MeV. A beamline following the accelerator has horizontal and vertical sections that include an alpha dipole and a “focus sextupole”. In the horizontal section, the alpha magnet, having a bend angle of 270° and a field index of 0.8, provides both vertical collimation and energy selection. In the vertical section, a focus sextupole converts the initial Gaussian beam distribution to a uniform distribution in one dimension without beam loss. We used a scanning magnet just ahead of the target to expand the beam in the orthogonal dimension. Using the French code TraceWin, we simulate the beam dynamics in this beamline by integrating electron trajectories through field maps of the magnets. We have determined experimentally that the focus sextupole creates a horizontal strip beam on target having a current density uniformity of better than 90 %. By scanning this strip beam vertically, we have achieved a two-dimensional current density uniformity of better than 90 %.

Effect of cooling surface temperature difference on the performance of high-temperature PEMFCs

Internal temperature distribution of the high-temperature proton exchange membrane fuel cell (HT-PEMFC) is affected by the cooling temperature, heat generation and reactant gas flow. Reasonable temperature control is helpful to improve the fuel cell performance and durability. In this work, a three-dimensional model that couples the reactant flows, species transport, heat transfer, charge transfer, and electrochemical reaction, was developed to simulate the HT-PEMFC operation. A solid mechanics model was established to analyze the stress distribution of the fuel cell. The polarization curves, distributions of temperature, membrane proton conductivity, current density and stress are investigated for different cooling surface temperature. Furthermore, the effect of assembly temperature on the stress of phosphoric acid-doped polybenzimidazole (PBI) membrane is discussed. Results reveals that the peak power density and uniformity of current density decrease with the increase of cooling surface temperature difference. The peak power density decreases by 9.14% when the temperature difference increases from 0 K to 40 K. The cooling surface temperature difference of less than 10 K and the voltage range in 0.5–0.7 V can achieve better current density uniformity and smaller current density change rate. In addition, the membrane in fuel cell has the highest stress, and increasing the assembly temperature is helpful to reduce the membrane stress. When the assembly temperature increases from 293.15 K to 343.15 K, the max and min compressive stresses in membrane in-plane decrease from 39.436 MPa to 31.416 MPa–24.934 MPa and 17.369 MPa at the temperature difference of 30 K, which decreases by 36.77% and 44.7%, respectively.

Elucidating non-uniform assembling effect in large-scale PEM fuel cell by coupling mechanics and performance models

The assembly of proton exchange membrane (PEM) fuel cell has a significant influence on contact pressure of BP and GDL, which affects key parameters of GDL including contact resistance, porosity, and permeability. In this study, a large-scale finite element method (FEM) PEM fuel cell model is developed considering realistic assembly, which is assembled by 14 bolts. The contact pressure at the interface of GDL and BP is converted into non-uniform contact resistance incorporated into a self-developed “3D + 1D” full PEM fuel cell multi-phase model with the active area of 108 cm2. The “3D + 1D” model simplifies part of components along through-plane direction into 1D model to improve calculation efficiency and stability. The results show that the performance reduces slightly when considering non-uniform contact resistance compared with that considering uniform contact resistance. The uniformity of current density and temperature distributions reduces evidently when considering non-uniform contact resistance affecting the performance and durability, which demonstrates the necessity of treatment of non-uniform contact resistance. Furthermore, the effects of porosity and permeability of deformed GDL under different preloading torques on performance are investigated. It is found that the contact resistance reduces first and then flats as the preloading torques increase, which results in the same trend of electronic ohmic loss, while the concentration loss nearly linearly increases. The simulation shows that the PEM fuel cell shows the best performance when the preloading torque is 3 Nm. This study provides some meaningful guidance for PEM fuel cell stack assembly.

An Investigation of Tin Electroless Deposition

Electroless metal/alloy deposition can be an efficient process in certain areas of microelectronic fabrication. In fact, it is often easier to obtain coatings of uniform thickness and composition using electroless deposition than with electrodeposition, since one does not have the current density uniformity problem of the latter. For example, we were able to develop a Ni(P) process as a replacement for the final aluminum interconnect level, significantly decreasing wafer processing cycle time, by selectively depositing a Ni(P) capping layer on the Cu bitline wiring level. In STTM MRAM, we successfully employed this Ni(P) capping process to enable the evaluation of memory state retention via functional testing in an air atmosphere at elevated temperatures (1).However, there is a need to explore materials + deposition methods for rapidly developing fields, such as Quantum computing, e.g., materials with superconducting properties. Conventional electroless metal deposition, utilizing a separate reducing agent, can deposit materials with unique and useful properties, such as phosphorus-containing alloys in the case of hypophosphite reducing agents. This talk discusses work we have carried out on electroless tin deposition, including aspects of electroless solution preparation and stability, copper substrate surface preparation and catalyzation, and the mechanisms of electroless deposition and solution decomposition.Electroless processes can deposit a limited number of materials, especially pure metals. This is in part due to conventional electroless processes requiring catalytically active surfaces both to initiate the deposition reaction and to sustain it, the heterogeneous oxidation of the reducing agent being a kinetically hindered process, often with multiple reaction pathways (2). Though not possessing good catalytic activity due to its Periodic Table related, p -block element status, pure Sn, an environmentally robust, superconducting metal, can be electrolessly deposited through a disproportionation reaction involving stannous ions (3) in an alkaline aqueous medium.We achieved electroless Sn deposition rates of up to 8 – 9 μm/hr for tartrate-citrate complexed electroless Sn solutions in the temperature range 80 – 85 ⁰C with sodium and potassium hydroxides to adjust alkalinity. We found that either in-house formulated, or commercially available, immersion Sn solutions deposited a uniform Sn catalyst layer (≤ 0.5 μm) to initiate the electroless Sn deposition reaction on copper; however, improperly formulated immersion Sn solutions rapidly developed precipitates due to tin ion hydrolysis.The biggest technical challenge was minimizing unwanted electroless deposition of tin in bulk solution, i.e., deposition not associated with the catalytically active substrate surface. Tin oxide (SnO) is known to be metastable at ambient conditions and to decompose at temperatures above 300 ⁰C with “noticeable rate” into Sn and SnO2 (4). Thus, removal of filterable hydrolysis products of Sn(II) following solution preparation was important, but not always sufficient, for obtaining solutions that were viable for several days of use. The reasons for, and mechanisms of, electroless Sn solution decomposition do not appear to have been adequately addressed in the literature.We will show SIMS analysis of both immersion and electroless Sn layers along with synchrotron X-Ray analysis results of immersion Sn catalyst films on Cu to determine the extent of Sn-Cu intermetallic formation following their formation. We will discuss the current understanding of the mechanism of electroless Sn deposition including that of concomitant H2 gas evolution. We will conclude with contrasting the Ni(P) and Sn electroless processes in terms of ease of operation and reliability for routine processing. † Present address: Solvay, 1937 West Main Street, Stamford 06902, CT. ‡ Quantum intern at the IBM TJ Watson Research Center, Summer 2019, 2020 and 2021.[1]. E. J. O'Sullivan, C. Camagong et al., 2019 Meet. Abstr. MA2019-02 916; https://doi.org/10.1149/MA2019-02/15/916.[2]. E. J. O'Sullivan, Ch 5, Advances in Electrochemical Science and Engineering, Volume 7, https://doi.org/10.1002/3527600264.ch5.[3]. A. Molenaar and J. W. G. de Bakker, 1989, J. Electrochem. Soc. 136, 378 and refs therein; H. Koyano, M. Kato, and M. Uchida, 1991, Plating and Surface Finishing, 78, 68-74 and refs therein.[4]. H. Giefers et al, 2005, Solid State Ionics, 176, 199-207; https://doi.org/10.1016/j.ssi.2004.06.006. Acknowledgements The authors gratefully acknowledge the efforts of the staff of the Microelectronics Research Laboratory (MRL) at the IBM T. J. Watson Research Center, where some of the fabrication work described in this talk was carried out.

Multi-objective optimization of graded catalyst layer to improve performance and current density uniformity of a PEMFC

The optimal use of compositions (platinum and ionomer) in cathode catalyst layers (CCLs) is essential to enhance the performance and improve the current density uniformity of proton exchange membrane fuel cells (PEMFCs). This paper presents a numerical study of graded CCL for a PEMFC. A one-dimensional, two-phase, non-isothermal model is developed, and the concept of the high power range (HPR) is defined. The effects of operating voltage and composition gradients across the catalyst layer thickness on output performance and current density distribution are investigated within the HPR. The results show an intense conflict between the output performance and current density uniformity, and only when biasing ionomer toward the membrane and operating in the higher spectrum of the HPR could improve them simultaneously. Otherwise, the improvement of one indicator means the deterioration of another. Finally, with the consideration of the interaction between the operating voltage and the gradients of platinum and ionomer, a multi-objective optimization is conducted to improve the aforementioned two indicators. Compared to the base case, the current density uniformity and the output performance were improved by 71.4% and 5.26%, respectively, which provides a solution to achieve higher performance and more uniform current density.

The design and evaluation of single-channel loopole coils at 7T MRI

Objective. Improving the local uniformity of field for awake monkey brain magnetic resonance imaging (MRI) at ultra-high fields while facilitating convenient placement and fixation of MRI-compatible multimodal devices for neuroscience study, can eventually advance our understanding of the primate’s brain organization. Approach. A group of single-channel RF coils including conventional loop coils and loopole coils sharing the same size and shape were designed for comparison; their performance as the transmit coil was quantitatively evaluated through a series of numerical electromagnetic (EM) simulations, and further verified by using 7T MRI over a saline phantom and a monkey in vivo. Main results. Compared to conventional loop coils, the optimized loopole coil brought up to 23.5% uniformity improvement for monkey brain imaging in EM simulations, and this performance was further verified over monkey brain imaging at 7T in vivo. Importantly, we have systematically explored the underlying mechanism regarding the relationship between loopole coils’ current density distribution and uniformity, observing that it can be approximated as a sinusoidal curve. Significance. The proposed loopole coil design can improve the imaging quality in awake and behaving monkeys, thus benefiting advanced brain research at UHF.

Effects of Cathode Gas Diffusion Layer Configuration on the Performance of Open Cathode Air-Cooled Polymer Electrolyte Membrane Fuel Cell

The design of a gas diffusion layer (GDL) is an effective way to manage water transport, thus improving the performance of air-cooled fuel cells. In the present study, three group designs of GDL with polytetrafluoroethylene (PTFE)—uniformly doped, in-planed sandwich doped and through-plane gradient doped—are proposed, and their effects on the performance of air-cooled fuel cells are explored by numerical simulation. The distribution of key physical quantities in the cathode catalyst layer (CCL), current density and the uniformity of current density distribution in the CCL were analyzed in detail. The results show that properly reducing the amount of PTFE in GDL is beneficial to promoting the water retaining capacity of air-cooled fuel cells, and then improving the performance of fuel cells. The performance of the in-plane sandwich GDL design cannot exceed the design with 10% PTFE uniformly doped, and this design will aggravate the uneven distribution of current density in CCL. Compared with the design of GDL with 40% PTFE uniformly doped, the current density can be improved by 22% when operating at 0.6 V by gradient increasing the PTFE content in GDL from the GDL/MPL interface to the gas channel. Furthermore, this design can maintain as good a current density uniformity as uniformly doping schemes.