Performance Of Proton Exchange Membrane Fuel Cell Research Articles

Bio-inspired sinusoidally-waved flow fields with exchange channels to enhance PEMFC performance

Wave-shaped structures inspired by cuttlefish fins have been applied to the design of flow fields for proton exchange membrane fuel cells (PEMFCs). However, the wave structures often cause high parasitic power. Herein, we intend to address this issue by introducing exchange channels (ECs) between neighboring wave channels. First, the performances of bio-inspired sinusoidally-waved flow fields (BSWFFs) of different sinusoidal parameters are compared to identify the optimal sinusoidal structure. Subsequently, ECs are introduced into BSWFFs with the optimal sinusoidal structure to obtain EC-BSWFFs, and EC-BSWFFs with different numbers of ECs are compared. The introduction of ECs improves the distribution of reactant gases, pressure distribution, water management and reduces parasitic power density. Specifically, the maximum net power density of the single-cell PEMFC with EC-12 is enhanced by 10.26% compared to that of the conventional parallel flow field. Moreover, as the number of ECs in EC-BSWFFs increases, the uniformity of pressure distribution gradually increases and the pressure drop becomes smaller, suggesting a balance between performance and durability. Therefore, this work affords valuable insights to solve the difficulties of excessive pressure drop and inhomogeneous reactant distribution for waved flow fields.

Intelligent control based on single-input interval type-2 fuzzy iPI and super twisting nonlinear sliding mode compensator for regulating PEMFC output voltage

The control of Proton Exchange Membrane Fuel Cell (PEMFC) is exceptionally challenging due to its complex nonlinearity, slow dynamics and load disturbance. In this paper, an Adaptive Model Free Control (AMFC) approach is introduced for regulating the PEMFC output voltage under load perturbation and measurement noise conditions. The proposed method consists of four sub-elements. Firstly, an Extended State Observer (ESO) based on a Single-Input Interval Type-2 Fuzzy intelligent PI (SI-IT-2-FLC-iPI) scheme is designed to enhance the performance of PEMFC. Secondly, a Nonlinear Sliding Mode Control-based Super Twisting Algorithm (NSMC-STA) is used as an auxiliary control approach to reduce the estimation error and ameliorate the system robustness. Thirdly, a Forgotten Recursive Least Square Error (FRLSE) is applied for adjusting the physical parameter of MFC and further ameliorating the control response. Finally, all these elements are merged together within what it is called Ultra Local Model (ULM).Through extensive simulation, the efficacy of the proposed regulator in accurately tracking the output signal is showcased, outperforming conventional controllers with remarkable improvements. The system achieves 0.001 steady-state error, 0% overshoot and settling time of approximately 8.9 s, which is good enough in the context of standalone fuel cell applications.

Optimization strategies and diagnostic techniques for water management in proton exchange membrane fuel cells

Proton exchange membrane fuel cells (PEMFCs) are efficient and zero emission energy conversion technology with promising application prospects towards carbon neutrality. The PEMFC's performance is largely affected by the poor water management, which is a substantial concern for long term durability. Herein, we overview the water management problems in PEMFCs, such as flooding and dehydration of membrane electrode assembly and analyze the causes and their impacts on the device performance. Major problems such as flooding impedes the gas transport and electrode reactions, while dehydration increases the membrane resistance and hinders proton transport. We have thoroughly overviewed several electrochemical and physicochemical diagnostic techniques for water management in PEMFCs. Additionally, material development and optimization approaches for the flow field structural design are explored in order to improve mass transport and wetting characteristics for optimized water management. Therefore, it is anticipated that this review will provide insights into the effective operation of PEMFCs as well as practical guidance for resolving water management issues in PEMFCs and associated technologies, like PEM water and CO2 electrolyzers.

A one-dimensional numerical model of carbon corrosion in catalyst layers of proton exchange membrane fuel cells

Understanding interaction between carbon corrosion and physicochemical processes inside proton exchange membrane fuel cells (PEMFCs) is important. A one-dimensional carbon corrosion model considering cathode catalyst layer (CCL) structure evolutions is established and coupled with one-dimensional PEMFC performance model. The coupled model is validated and employed to predict CCL structure evolution and PEMFC performance degradation during accelerated stress test. The results find that high relative humidity can enhance performance but accelerate carbon corrosion. Increasing carbon loading and decreasing ionomer weight can improve both performance and durability. Low Pt loading leads to reduced performance and durability. There exists an optimal carbon diameter leading to the best performance. Small carbon diameter can enhance cell durability. Proper gradient CCL design can enhance durability at cost of small initial performance reduction. Finally, an optimized structure is proposed with 21.7 % higher current density at 0.6 V and 5.2 % lower performance loss compared with base case.

A Review of Proton Exchange Membrane Degradation Pathways, Mechanisms, and Mitigation Strategies in a Fuel Cell

Proton exchange membrane fuel cells (PEMFCs) have the potential to tackle major challenges associated with fossil fuel-sourced energy consumption. Nafion, a perfluorosulfonic acid (PFSA) membrane that has high proton conductivity and good chemical stability, is a standard proton exchange membrane (PEM) used in PEMFCs. However, PEM degradation is one of the significant issues in the long-term operation of PEMFCs. Membrane degradation can lead to a decrease in the performance and the lifespan of PEMFCs. The membrane can degrade through chemical, mechanical, and thermal pathways. This paper reviews the different causes of all three routes of PFSA degradation, underlying mechanisms, their effects, and mitigation strategies. A better understanding of different degradation pathways and mechanisms is valuable in producing robust fuel cell membranes. Hence, the progress in membrane fabrication for PEMFC application is also explored and summarized.

Fe-N-C core–shell catalysts with single low-spin Fe(II)-N4 species for oxygen reduction reaction and high-performance proton exchange membrane fuel cells

Fe-N-doped carbon materials (Fe-N-C) are promising candidates for oxygen reduction reaction (ORR) relative to Pt-based catalysts in proton exchange membrane fuel cells (PEMFCs). However, the intrinsic contributions of Fe-N4 moiety with different chemical/spin states (e.g. D1, D2, D3) to ORR are unclear since various states coexist inevitably. In the present work, Fe-N-C core–shell nanocatalyst with single low-spin Fe(II)-N4 species (D1) is synthesized and identified with ex-situ ultralow temperature Mössbauer spectroscopy (T = 1.6 K) that could essentially differentiate various Fe-N4 states and invisible Fe-O species. By quantifying with CO-pulse chemisorption, site density and turnover frequency of Fe-N-C catalysts reach 2.4 × 1019 site g−1 and 23 e site−1 s−1 during the ORR, respectively. Half-wave potential (0.915 VRHE) of the Fe-N-C catalyst is more positive (approximately 54 mV) than that of Pt/C. Moreover, we observe that the performance of PEMFCs on Fe-N-C almost achieves the 2025 target of the US Department of Energy by demonstrating a current density of 1.037 A cm−2 combined with the peak power density of 0.685 W cm−2, suggesting the critical role of Fe(II)-N4 site (D1). After 500 h of running, PEMFCs still deliver a power density of 1.26 W cm−2 at 1.0 bar H2-O2. An unexpected rate-determining step is figured out by isotopic labelling experiment and theoretical calculation. This work not only offers valuable insights regarding the intrinsic contribution of Fe-N4 with a single spin state to alkaline/acidic ORR, but also provides great opportunities for developing high-performance stable PEMFCs.

The Lifetime of Hydroxyl Radical in Realistic Fuel Cell Catalyst Layer.

The lifetime of hydroxyl radicals (⋅OH) in the fuel cell catalyst layer remains uncertain, which hampers the comprehension of radical-induced degradation mechanisms and the development of longevity strategies for proton-exchange membrane fuel cells (PEMFCs). In this study, we have precisely determined that the lifetime of ⋅OH radicals can extend up to several seconds in realistic fuel cell catalyst layers. This finding reveals that ⋅OH radicals are capable of carrying out long-range attacks spanning at least a few centimeters during PEMFCs operation. Such insights hold great potential for enhancing our understanding of radical-mediated fuel cell degradation processes and promoting the development of durable fuel cell devices.

Characterization and prediction of micro channel depth of ultra-thin bipolar plates for PEMFCs

In this study, a combination of experimental and statistical methods were employed to precisely determine the micro channel depth in ultra-thin metallic bipolar plates fabricated from 316 stainless steel with a thickness of 0.1 mm. The investigation centers on the rubber pad forming process and its role in the production of these critical components for Proton Exchange Membrane Fuel Cells (PEMFCs). To advance the understanding of this manufacturing process, experimental tests were designed using a Design of Experiment (DOE) technique and subsequently developed a predictive model using Response Surface Methodology (RSM). The research reveals a direct, quantifiable relationship between the channel depth in metallic bipolar plates and the magnitude of the applied force. Also, the pivotal role of rubber thickness as a dominant factor influencing channel depth was explored. Furthermore, it is revealed that augmenting the channel depth in these plates is attainable through a reduction in rubber hardness and an increase in rubber thickness. However, the benefits diminish once the rubber layer thickness exceeds a specific threshold. Moreover, the results underscore that the primary influential factors in this process include force, hardness, thickness, as well as the interplay between force and rubber thickness. The proposed model's accuracy is reaffirmed through an average error rate of approximately 5.39%, signifying its reliability in predicting microchannel depth. This research contributes novel insights into the manufacturing of ultra-thin metallic bipolar plates for PEMFCs, shedding light on the critical parameters influencing channel depth and their interrelationships. The significance and engineering value of this work lies in its potential for enhancing the design and manufacturing of metallic bipolar plates for PEMFCs. Precise control of microchannel dimensions is crucial for enhancing PEMFC performance and efficiency. This research not only advances clean energy technology but also contributes to the broader goal of achieving sustainable energy solutions, making it a noteworthy and timely contribution to the field.

The impact of baffle and taper channel tilt angle on the output performance of proton‐exchange membrane fuel cells

AbstractThe performance and durability of proton‐exchange membrane fuel cells (PEMFCs) are constrained by fuel delivery and water management. Based on parallel and serpentine flow fields, the effects of triangular baffles (30°, 45°, and 60°) and conical runners (1°, 2°, and 3°) on the performance output of PEMFC at different angles are studied. The three‐dimensional and multi‐phase models are established by using the simulation software package (ANSYS FLUENT). The findings demonstrate that the battery's output performance reaches its peak when the baffle angle is set at 45°. When the output current density is 0.7 A/cm2, the power density of the 45° baffle increases by 18.87%. The pressure loss is not only lower than that of the 60° baffle but also exhibits no significant difference when compared to the 30° baffle. In addition, the introduction of conical channels has enhanced the output performance of PEMFCs in comparison to the traditional serpentine flow field. The power density of the 2°tapered channel exhibits a 12.65% increase when the output current density reaches 0.8 A/cm2. However, the performance output of the 3°tapered channel is inferior to that of the conventional serpentine flow field.

Influence of crack formation at the catalyst layer and membrane interface on the performance of PEMFC

ABSTRACT Temperature and humidity cycling during frequent startup-shutdown of proton exchange membrane (PEM) fuel cell (PEMFC) can lead to crack formation in the catalyst layer (CL) or even at the interface between the CL and PEM, decreasing the effective activation area and degrading the fuel cell performance. This study develops a two-dimensional PEMFC model using COMSOL software which is well validated, and investigates the effect of different lengths and positions of CL/PEM interface crack (delamination) on the mass transport and performance of PEMFC. The results show that both the crack length and position have significant influence on the cell performance, especially at high current density. The presence of crack leads to an uneven distribution of cell current density, and the performance of the cell decreases with the increase of the crack length due to decreased activation area. The crack near the inlet has the greatest adverse impact on the cell performance, compared to other positions near the outlet or in the middle of the rib. Compared to the cell without cracks, the decrement in current density is 5.05%, 9.55% and 15.52%, respectively, for the crack in the middle of the rib, near the outlet and near the inlet.

Variation in performance and characteristics of long-term operated gas diffusion layer in a fuel cell electric vehicle

Proton-exchange membrane fuel cells (PEMFCs) operate at low temperatures and are used in household appliances and vehicles because of their high power density and fast start-up/shut-down capabilities. Previous research has focused on improving the performance of PEMFCs by enhancing their structures and constituent materials of their components. However, as PEMFCs are being commercialized, their durability remains a critical challenge that needs to be addressed. Although numerous studies have evaluated the durability of membrane electrode assemblies (MEA), limited research has been conducted on the durability of gas diffusion layers (GDL). The GDL, with its nanometer-to micrometer-sized pores and thickness of hundreds of microns, is prone to mechanical degradation during long-term operation. Moreover, the GDL is susceptible to carbon corrosion because it primarily consists of carbon materials, similar to the catalyst layer. Therefore, to ensure the performance and longevity of PEMFCs, it is of utmost importance to investigate the durability of the GDL. This study quantitatively investigates the variations in the performance and mechanical and chemical characteristics of GDLs during an extended period of operation in a fuel cell electric vehicle (FCEV), and two types of GDLs are analyzed.

An Electrochemical Performance Model Considering of Non-Uniform Gas Distribution Based on Porous Media Method in PEMFC Stack

Proton exchange membrane fuel cell (PEMFC) is significant and favorable to the long-range and short refueling time in the vehicle industry. However, the non-uniform distribution of gas flow supply, particularly in the fuel cell stack is neglected in the electrochemical model for PEMFC performance optimization. The purpose of this study is to break through this limitation to establish an optimized electrochemical fuel cell performance model, with porous media methods considering the non-uniform gas flow distribution in fuel cell stack with different compression of the gas distribution layer (GDL). The numerical models are validated by experimentation of a practical fuel cell stack. For the established fuel cell model, there is a 5% difference between the maximum and minimum speeds of various flow channels in the anode flow field under 10% GDL compression. Furthermore, the single-channel electrochemical performance model is optimized by considering the non-uniform gas flow distribution of the fuel cell stack. The results of the optimized electrochemical fuel cell performance model demonstrate that the correlation coefficient between the experiment results and the simulation results is nearly 99.50%, which is higher than that of the original model under 20% GDL compression. This established model is effective in enhancing the prediction accuracy of the PEMFC performance.

Sealing Performance of Ethylene Propylene Diene Monomer Seals for Proton Exchange Membrane Fuel Cells

The reliability of the sealing system of a proton exchange membrane fuel cell (PEMFC) is a prerequisite for ensuring the efficient and safe operation of the cell stack. In consideration of the actual assembly process, a local model of single‐cell sealing structure is constructed using a rounded corner rectangular sealing gasket structure. Apart from that, the effects of fluid pressure, bipolar plate offset, sealing gasket size, steady‐state temperature field, and seal structure on the sealing performance of PEMFC are investigated. As shown by results, with the increase of fluid pressure and sealing gasket width, the contact pressure is increased and the sealing performance is also improved. However, the increase of sealing gasket height is unfavorable to the stability and sealing performance of the stack. Meanwhile, excessive offset error leads to a sharp decrease in contact length and contact pressure at the sealing interface, which reduces the stability of the stack. With the increase of the operating temperature, the thermal expansion of the gasket increases and the contact performance improves significantly. Seals with rectangular structure have some advantages in terms of contact stability and standard deviation of contact pressure.

Two-phase flow dynamics study in the trapezoidal gas channel of PEM fuel cell based on lattice Boltzmann model

ABSTRACT Water management is a critical challenge in ensuring the performance and durability of low-temperature proton exchange membrane fuel cells (PEMFCs). This study utilizes the phase-field lattice Boltzmann method to conduct three-dimensional numerical simulations, investigating the dynamics of two-phase flow in the cathode gas channel (GC) of PEMFC with a trapezoidal cross-section. The effects of the water inlet location, the surface wettability of GC, the open angle of GC, and the air velocity on liquid water distribution and discharge are analyzed. The results indicate that positioning the water inlet in the middle of the GC significantly enhances PEMFC performance while having minimal impact on average pressure drop. A wall contact angle of 70° or 110°Can optimize fuel cell performance from different directions. Setting a wall contact angle at 70° optimizes gas flow stability and maintains a low-pressure drop value for the GC. A wall contact angle of 110° focuses on optimizing gas reactant diffusion ability into porous electrodes and GC drainage rate. An opening angle of 55° for the trapezoidal gas channel improves overall fuel cell performance. Increasing air velocity facilitates the film flow formation of liquid water on top wall surfaces within the GC.

Effects of gradient structures of cathode catalyst layers on performance and durability of proton exchange membrane fuel cells

Improving performance and durability of proton exchange membrane fuel cells (PEMFC) is crucial for promoting commercial applications. Deep understanding of the underlying degradation mechanisms is still lacking. In this study, a two-way coupling performance-degradation model is established by incorporating one-dimensional (1D) Platinum (Pt) degradation model into 1D PEMFC performance model, which can predict Pt degradation phenomenon considering Pt dissolution, Pt2+ diffusion and reprecipitation in cathode catalyst layers (CCLs) and resulting performance loss. Effects of gradient CCL structures in terms of ionomer weight, Pt loading and Pt particle size on degradation and performance are investigated. The results show that multi-layer CCLs with more ionomer, more Pt loading, and/or smaller particles near membrane have higher performance, while the opposite gradients present enhanced anti-degradation capacity. Wave-like spatial distributions of Pt mass retention are observed in gradient CCLs, with significant difference across the sub-layer interface. Combined effects of two gradient distributions are also investigated. It is found that for performance, simply add-up roles are followed, namely combining two gradient distributions with higher performance can obtain higher performance, and vice versa. For durability, synergy effects are identified, in which two gradient structures with opposite final Pt mass distribution have competitive influence on Pt2+ local transport, with local Pt2+ diffusion suppressed, the catalyst distribution uniformity improved and performance loss alleviated. The gradient CCL structure considering the balance of performance and durability is identified based on 28 structures studied. Such add-up roles for performance and synergy effects for durability provide new insights for improving the design of PEMFCs.

Design and performance optimization of a lattice-based radial flow field in proton exchange membrane fuel cells.

The design of the flow field structure in Proton Exchange Membrane Fuel Cells (PEMFCs) plays a pivotal role in determining their electrochemical performance. This study presents a lattice-based radial flow field configuration designed to improve PEMFC efficiency. The difference between the flow field and the traditional flow field is that the flow field is segmented by a small cylindrical rib instead of a longer rib. The research employs COMSOL Multiphysics simulation software to establish the model of the operating conditions of PEMFCs, focusing on analyzing how the number of rib branches and the minimum rib radius influence the oxygen distribution, water distribution, and pressure drop in the system. The results demonstrate that varying the number of rib branches and the minimum radius of the cylindrical ribs has a pronounced impact on the PEMFC's performance. Furthermore, a comparative analysis of multiple design configurations reveals the optimal operating parameters. Specifically, within a quarter of the computational domain, the configuration featuring a minimum rib radius of 0.135 cm and six rib branches delivers the best electrochemical performance.

Current status of research on composite bipolar plates for proton exchange membrane fuel cells (PEMFCs): nanofillers and structure optimization.

The proton exchange membrane fuel cell (PEMFC) is an efficient and clean energy source with promising applications. However, drawbacks such as high cost and low durability limit its application. Bipolar plates are an important component of PEMFCs, which not only account for a large proportion of the price and quality, but also affect the performance and durability of PEMFCs. Unlike traditional graphite and metal bipolar plates, composite bipolar plates have the advantages of easy processing, low cost, and corrosion resistance, but their lower performance limits their practical applications. This paper firstly summarizes the current research progress of various nanofillers used to improve the performance of composite bipolar plates, and discusses the improvement of the performance of composite bipolar plates by different forms and types of nanofillers. The morphological characteristics of different types of nanofillers and their effects on the improvement of conductive pathways are also analyzed. Subsequently, the means of structural optimization of composite bipolar plates are summarized, and specific optimization methods for phase interface, graphite/resin dispersion morphology, and conductive network structure are discussed in detail. Finally, challenges are discussed. Overall, this review can provide a reference for future research on composite bipolar plates.

Catalytic effects of graphene structures on Pt/graphene catalysts.

Pt/C catalysts have been considered the ideal cathodic catalyst for proton exchange membrane fuel cells (PEMFCs) due to their superior oxygen reduction reaction (ORR) catalytic activity at low temperatures. However, oxidation and corrosion of the carbon black support at the cathode result in the agglomeration of Pt particles, which reduces the active sites in the Pt/C catalyst. Graphene supports have shown great promise to address this issue, and therefore, finding out the main structural features of the graphene support is of great significance for guiding the rational construction of graphene-based Pt (Pt/graphene) catalysts for optimized ORR catalysts. In order to systematically study the influence of the structural features of the graphene support on the electro-catalytic properties of Pt/graphene catalysts, we prepared porous nitrogen-doped reduced graphene oxide (P-NRGO), nitrogen-doped reduced graphene oxide (NRGO), treated P-NRGO (TP-NRGO) and reduced graphene oxide (RGO) with different nitrogen species contents (7.76, 7.54, 3.24, and 0.14 at%), oxygen species contents (18.68, 18.12, 6.34 and 21.12 at%), specific surface areas (370.4, 70.6, 347.7 and 276.2 m2 g-1) and pore volumes (1.366, 0.1424, 1.3299 and 1.0414 cm3 g-1). The ORR activity of the four Pt/graphene catalysts when listed in the order of their half-wave potentials (E 1/2) and peak power densities was found to be as Pt/P-NRGO > Pt/NRGO > Pt/TP-NRGO > Pt/RGO. The long-term durability of Pt/P-NRGO for the operation of H2-air PEMFCs is better than that of commercial Pt/C catalysts. The excellent ORR catalytic performance of Pt/P-NRGO compared to that of the other three Pt/graphene catalysts is ascribed to the high nitrogen species content of P-NRGO that can facilitate the uniform dispersion of Pt particles and provide accessible active sites for ORR. The results indicate that the specific surface area (SSA) and heteroatom dopants have strong influence on the Pt particle size, and that the nitrogen species of graphene supports play a more important role than the oxygen species, specific surface area and pore volume for the Pt/graphene catalysts in providing accessible active sites.

Effect of Engineered Cracks in Catalyst Layers on PEMFC Catalyst Layer Durability

Proton exchange membrane fuel cells (PEMFCs) are expected to play a pivotal role in decarbonizing the transportation sector, and particularly heavy-duty vehicles (HDVs). However, improvements in durability are needed for PEMFCs to compete with state-of-the-art power sources for HDVs. Here, we examine how catalyst layer (CL) cracks that are engineered affect the CL durability by using patterned silicon templates to control the CL crack density at the micrometer scale. Electrochemical analyses show that the initial PEMFC performance is relatively unaffected by crack density, but the performance after durability testing was strongly affected. Specifically, CLs with high crack density showed higher performance relative to CLs without cracks after application of a carbon corrosion accelerated stress test. Electrochemical analyses coupled with X-ray computed tomography and scanning transmission electron microscopy with energy dispersive X-ray spectroscopy showed that the cracks provide shorter oxygen diffusion pathways to reaction sites, leading to decreased oxygen transport resistance. Additionally, we observed that the catalyst durability is unaffected by cracks. Our results provide a mechanistic explanation of the role of cracks in CL durability.

Thermodynamic Evaluation of a Combined SOFC-PEMFC Cycle System

Solid oxide fuel cell (SOFC) technology offers a promising way to reduce maritime greenhouse gas (GHG) emissions.Integration with a proton exchange membrane fuel cell (PEMFC) allows unreacted hydrogen, produced in the SOFC stack, to be reused and increase the electrical efficiency of the system. In this study, the Cycle Tempo software is used to model a SOFC-PEFMC combined cycle system operating on methane. The system is thermodynamically analysed to reveal the influence of SOFC fuel utilisation, cell voltage, operating temperature and PEMFC cell voltage on the system performance. A multivariable parametric analysis is applied to generate contour plots of net electrical efficiency and fraction of total power produced by the PEMFC. The analysis shows that increasing the cell voltage of both the SOFC and PEMFC has a positive influence on efficiency, whereas increasing the fuel utilisation reduces the system efficiency. Efficiencies in the range of 50-68% can be achieved. Model assumptions for PEMFC operating parameters are verified to exert little influence on the system efficiency, which confirms the assumption of constant values for these parameters. This study highlights the high-efficiency potential of the combined system and the difficulties that arise from thermally integrating an SOFC with a PEMFC.