Proton Exchange Membrane Fuel Cell Research Articles

Fundamental and Practical Aspects of Break-In/Conditioning of Proton Exchange Membrane Fuel Cells.

Proton exchange membrane fuel cells (PEMFCs) have proven to be a promising power source for various applications ranging from portable devices to automotive and stationary power systems. The production of PEMFC involves numerous stages in the value chain, with each stage presenting unique challenges and opportunities to improve the overall performance and durability of the PEMFC stack. These include steps such as manufacturing the key components such as the platinum-based catalyst, processing these components into the membrane electrode assemblies (MEAs), and stacking the MEAs to ultimately produce a PEMFC stack. However, it is also known that the break-in or conditioning phase of the stack plays a crucial role in the final performance as well as durability. It involves several key phenomena such as hydration of the membrane, swelling of the ionomer, redistribution of the catalyst and the creation of suitable electrochemical interfaces - establishment of the triple phase boundary. These improve the proton conductivity, the mass transport of reactants and products, the catalytic activity of the electrode and thus the overall efficiency of the FC. The cruciality of break-in is demonstrated by the improvement in performance, which can even be over 50 % compared to the initial state. The state-of-the-art approach for the break-in of MEAs involves an electrochemical protocol, such as voltage cycling, using a PEMFC testing station. This method is time-consuming, equipment-intensive, and costly. Therefore, new, elegant, and cost-effective solutions are needed. Nevertheless, the primary aim is to achieve maximum/optimal performance so that it is fully operational and ready for the market. It is therefore essential to better understand and deconvolute these complex mechanisms taking place during break-in/conditioning. Strategies include controlled humidity and temperature cycling, novel electrode materials and other advanced break-in methods such as air braking, vacuum activation or steaming. In addition, it is critical to address the challenges associated with standardisation and quantification of protocols to enable interlaboratory comparisons to further advance the field.

Exceptionally Stable Polymer Electrolyte Membrane Fuel Cells Enabled by One-Pot Sequential Atomic Layer Deposition of Titania and Platinum

Exceptionally Stable Polymer Electrolyte Membrane Fuel Cells Enabled by One-Pot Sequential Atomic Layer Deposition of Titania and Platinum

Nitrogen, Fluorine, and Phosphorus Tri‐Doped Porous Carbon with High Electrical Conductivity as an Excellent Metal‐Free Electrocatalyst for Oxygen Reduction Reaction

AbstractToday's oxygen reduction reaction (ORR) depends on the precious metal Pt‐based catalysts, limiting the large commercialization of promising energy conversion technologies such as proton exchange membrane fuel cells (PEMFCs) and metal‐air batteries. Therefore, the rational design of low‐cost and highly efficient electrocatalysts for ORR is strongly desired. Herein, we report a porous carbon doped with nitrogen, fluorine, and phosphorus (N, F, P tri‐doped carbon) prepared via only a heating process using low‐cost glycine, ammonium fluoride, and phytic acid as precursors. X‐ray photoelectron spectroscopy (XPS) analysis revealed the existence of pyridinic‐N and the co‐existence of graphitic‐N and oxidized graphitic‐P, which can be active sites, with semi‐ionic C−F bonds highly boosting ORR activity. Remarkably, the resultant N, F, P tri‐doped carbon exhibited outstanding activity for the ORR with an onset potential comparable to that of commercial 20 wt % Pt/C catalyst, the half‐wave potential superior to that of the Pt/C catalyst, and the electron transfer number close to 4.

Performance of the multi-U-style structure based flow field for polymer electrolyte membrane fuel cell

The design of the reactant gas flow field structure in bipolar plates significantly influences the performance of proton exchange membrane fuel cells (PEMFCs). In this study, we introduced four innovative U-shaped flow field designs, namely: In-Out Multi-U, Out-In Multi-U, Distro In-Out Multi-U, and Distro Out-In Multi-U. To investigate the impact of these various flow fields on PEMFC performance, we conducted computational fluid dynamics (CFD) numerical simulations, validated through model experiments. Our results indicate that the Distro Out-In Multi-U flow field offers notable advantages compared to the conventional parallel flow field (CPFF) and conventional serpentine flow field (CSFF). These benefits include reduced inlet and outlet pressures, lower liquid water content, more uniform liquid water distribution, and a more even current density distribution. Furthermore, the Distro Out-In Multi-U design demonstrates improved efficiency, consuming less H2 (91.9%) than the CSFF while achieving a higher net power density output (10.1%). As a result, for the same power output, the Distro Out-In Multi-U utilizes only 83.5% of the H2 consumed by the CSFF. In summary, the U-shaped structured flow field exhibits superior output performance, enhanced energy efficiency, and improved resistance to flooding. These findings suggest that the U-shaped flow field design holds significant potential as a reactive flow field for PEMFCs.

Scaling of ultrashort-pulsed laser structuring processes for electromobility applications using a spatial light modulator

The structuring of lithium-ion battery (LIB) electrodes and the diffusion media (DM) for polymer electrolyte membrane fuel cells (PEMFCs) with ultrashort laser pulses enables improved performance characteristics of both technologies. However, the transfer of the approaches from a laboratory scale to a commercial use has previously been hindered by the low average output power of ultrashort-pulsed (USP) laser beam sources and the limited productivity of single-beam structuring using scanning optics. Recent advancements in the development of USP laser systems have led to a steady increase in the available output power, thereby enabling new fields of applications. This study aims at accelerating the USP laser structuring of LIB electrodes and DM for PEMFCs to industrially relevant processing rates by comparing a single-beam with a multibeam structuring process regarding ablation characteristics and quality. For the multibeam strategy, the shape of the laser beam was modified by a spatial light modulator (SLM). In addition to microholes, the insertion of microchannels was investigated to demonstrate the high flexibility of state-of-the-art SLMs. The geometry of the created structures was measured with a laser scanning microscope, and the different layers were tested for their geometrical and electrochemical properties to compare both technologies. The results confirmed that applying an SLM enables high-quality microstructures with significantly higher structuring rates. Furthermore, this contribution includes a theoretical analysis of the specifications required for a laser setup to reach an industrially relevant productivity of the structuring processes.

Two-Phase Fluid Dynamics in Proton Exchange Membrane Fuel Cells: Counter-Flow Liquid Inlets and Gas Outlets at the Electrolyte-Cathode Interface

Abstract This study uses a volume of fluid method to model two-phase interactions in a T-shaped GDLand gas channel (GC) assembly, with GDL geometry derived from nano-computer tomography. his research investigates the impact of the size and shape of liquid invasion on the liquid-gas behavior in the cathode GDL and GC using five liquid injection configuration. Simulations also incorporate GDLgas outlets, integrating them with a tailored liquid inlet setup. Comparisons of simulations with and without air outflow show distinct counter-flow interactions, highlighting variations in water distribution and discrepancies in two-phase transport across the GCs.

An MPPT Controller with a Modified Four-Leg Interleaved DC/DC Boost Converter for Fuel Cell Applications

A fuel cell system can produce electricity and water more efficiently while emitting near-zero emissions. Internal constraints and operating parameters such as hydrogen, temperature, humidity levels, and oxygen gas partial pressures trigger a nonlinear power characteristic in a typical fuel cell stack, resulting in reduced overall system efficiency. Consequently, it's critical to get the most power out of the fuel cell stack while minimizing fuel use. This study examines and proposes a radial basis function network (RBFN) based maximum power point tracking technique (MPPT) for a 6-kW proton exchange membrane fuel cell (PEMFC) system. The proposed MPPT algorithm modulates the duty cycle of the modified four-leg interleaved DC/DC boost converter (MFLIBC) to extricate the maximum power from the fuel cell system. To validate the execution of the proposed controller, the outcome is related to the various MPPT control strategies such as PID & Mamdani fuzzy inference systems. Finally, it was observed that the proposed RBFN controller has achieved an enhanced efficiency of 83.2 % relative to the PID and fuzzy logic controllers of 75.5 % and 77.4 % respectively. The efficiency of the proposed configuration is analysed using the MATLAB/Simulink platform.

Zeolite Framework-Anchored Carbon-Doped White Graphene as Antipoisoning Cathode Materials for Proton-Exchange Membrane Fuel Cells

Zeolite Framework-Anchored Carbon-Doped White Graphene as Antipoisoning Cathode Materials for Proton-Exchange Membrane Fuel Cells

Acausal Fuel Cell Simulation Model for System Integration Analysis in Early Design Phases

Hydrogen technologies have the potential to reduce aviation’s CO2 emissions but come with many challenges. This paper introduces a scalable hydrogen fuel cell model tailored for system integration analysis in early aircraft design phases. The model focuses on Proton Exchange Membrane Fuel Cells (PEMFCs) and is based on thermodynamic equations and empirical data to simulate performance under different ambient and operating conditions; it also includes a simplified model of the Balance of Plant (BOP) systems and is implemented in OpenModelica. The model performance is validated through a comparison of the simulated polarization curves with real datasheet data. A case study highlights the peculiarities of this model by studying the sizing of the fuel cell stacks for a modified ATR 72 aircraft. The developed model effectively supports the early design exploration of the aircraft with a greater level of detail for system integration studies, essential to better explore the potential of aircraft featuring hydrogen-based power systems.

Enhanced proton transfer in proton exchange membrane fuel cells via novel nanocomposite membrane incorporating (3-Mercaptopropyl)trimethoxysilane-graphene oxide and basic amino ligands: A synergistic acid-base approach

A nanocomposite polymer electrolyte membrane (MGC) was synthesized by blending MPTS (HS(CH2)3Si(OCH3)3) and graphene oxide (GO) nanosheets at varying weight ratios (91.5 to 9.5, respectively) for proton exchange membrane fuel cell (PEMFC) applications. By covalently modifying the GO support with MPTS through a silane modification process, the acidic MGC matrix is formed. The blending process, with ultrasonication and vigorous stirring, initiates two significant reactions in reactive MPTS: first, the conversion of methoxy groups (Si–OCH3) to silanols (Si-OH); second, the potential condensation of silanol groups to form siloxane bonds (Si–O–Si), followed by oxidation of sulfhydryl groups to sulfonic acid (-SO3H) groups by hydrogen peroxide. The resulting -SO3H groups connected to the siloxane network (Si-O-Si) adjacent to the GO. Two basic amino ligands – dopamine, and aminopropyl trimethoxysilane (APTES) were incorporated into the MGC matrix to establish acid-base pairs, promoting swift proton transport. These additions, at weight ratios of (0.5, 1, 2, and 7) wt%, synergistically contributed to the MGC matrix, forming effective proton channels. Various analytical techniques, including field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS), were employed to assess the impact of functionalized basic amino groups on the MGC matrix. Notably, the MGC membrane containing 2 wt% of PDA as basic amino ligands exhibited optimal performance, showcasing an in-plane proton conductivity of 115.10 mS cm-1 under fully hydrated conditions at 90 °C, and the maximum power density (MPD) of 170.74 mW cm-2 with a current density of 1051.46 mA cm-2 at 60 °C and 100 % relative humidity (RH). In contrast, the MGC membrane, devoid of amino ligands, exhibited a comparatively low in-plane conductivity of 44.32 mS cm⁻¹ under identical conditions at 90 °C. Additionally, it recorded the MPD of 48.5 mW cm⁻², corresponding to a current density of 313.25 mA cm⁻² at 60 °C and 100 % RH. This study introduces an innovative approach for developing high-performance nanocomposite membranes for PEMs and related applications.

Simulation-based study of local hydrogen crossover dynamics and their effects on proton exchange membrane fuel cells

The hydrogen (H2) crossover significantly impacts the performance and durability of proton exchange membrane fuel cells (PEMFCs). However, understanding the intricate dynamics of local H2 crossover in fuel cells is challenging due to complex transport and reactions. This study introduces advanced two-phase, three-dimensional PEMFCs transient models, incorporating H2 dissolution, diffusion/convection, and surface reactions, providing a comprehensive analysis of the interplay between H2 crossover and local charge, mass and heat. The study emphasizes the substantial influence of geometric and operational parameters on both H2 crossover flux and distribution uniformity by adjusting local membrane water and H2 concentrations. Elevated H2 crossover flux is often accompanied by non-uniform distribution, particularly noticeable under conditions of elevated temperature, backing pressure, and relative humidity (RH). Sensitivity analysis reveals load-dependent parameter effects, with RH exerting the most significant impact at lower loads compared to temperature and pressure, with its effect diminishing at higher loads. Additionally, H2 crossover results in 1–10 mV decrease in dynamic voltage loss but 20–57 mV increase in steady-state voltage loss. The steady voltage loss diminishes notably with increasing current load before slightly rising 1–3 mV, attributed to reduced activation overpotential for the oxygen reduction reaction utilizing excess electrons and protons from permeated H2. The subsequent increase is associated with heightened ohmic polarization losses due to membrane dehydration at elevated catalyst layer temperatures near the channel. This study contributes to advancing our understanding of H2 crossover, providing valuable insights for the development of mitigation strategies in fuel cell operation.

Pt-decorated oxygen-vacancy-tuned high temperature hydrogen-annealed WO3 as an efficient anode electrocatalyst for PEMFC

One of the most significant steps for the widespread application of Proton Exchange Membrane Fuel Cells (PEMFC) is the development of an efficient and corrosion-resistant electrocatalyst for Hydrogen Oxidation Reaction (HOR). To achieve an enhanced electrocatalytic activity towards HOR, we developed a carbon-free electrocatalyst that performs on par with the Pt/C commercial-based catalyst. Pt nanoparticles dispersed on hydrogenated WO3 surfaces were synthesized and experimentally shown to be an efficient HOR electrocatalyst. Furthermore, different characterizations and electrochemical studies validate the performances of all the hydrogenated samples. Pt/a-WO3/H400, hydrogenated at 400 °C, exhibits excellent electrocatalytic activity in terms of onset potential, limiting current density, and electrochemical surface area (ECSA). The membrane electrode assembly (MEA) was fabricated, and its single-cell performance was carried out using Pt/a-WO3/H300, Pt/a-WO3/H400, and Pt/a-WO3/H500 at the anode with Pt loading of 0.125 mg/cm2. The single-cell performance of Pt/a-WO3/H400 as anode electrocatalyst has the highest power density (540 mW/cm2) at 50 °C and high durability, compared to Pt/C. The enhanced electrocatalytic performance is attributed to the synergistic catalytic effect between Pt nanoparticles and the WO3-x interface. This occurs due to the preferential orientation of the highly active (002) facet and the creation of an optimum amount of oxygen vacancies due to the hydrogenation impact.

Numerical simulation of a hybrid energy system proposed for low carbon data center

Low-carbon energy application for both large grid and distributed energy consumers is an urgent problem to be solved. Data centers (DC) are the typical distributed large-size energy consumers, and the application of renewable energy and energy storage is a promising solution for data center decarbonization. This paper developed a complete hybrid energy system (HES) simulation process for data center applications. The photovoltaic (PV) cell, hydrogen electrolysis, hydrogen storage, proton exchange membrane fuel cell (PEMFC), lithium battery (BAT), grid, and data center load are considered in the HES. A one-dimensional two-phase flow PEMFC model is developed. The detailed mass transfer process inside the PEMFC cell is modeled. The PEMFC model-solving algorithm is developed and integrated into the HES simulation program. The energy management system (EMS) based on a logical flow chart energy management strategy is integrated by editable subfunction. The HES simulation program is coded and implemented based on the MATLAB-SIMULINK environment. The yearly HES performance simulations are conducted and analyzed for a 200 kW data center in Xi’an with different HES parameters and an appropriate HES parameter arrangement is provided. The main contribution of this work is the development of an editable HES simulation program that is extensible for data center applications.

A Janus Platinum/Tin Oxide Heterostructure for Durable Oxygen Reduction Reaction.

Designing efficient and durable electrocatalysts for oxygen reduction reaction (ORR) is essential for proton exchange membrane fuel cells (PEMFCs). Platinum-based catalysts are considered efficient ORR catalysts due to their high activity. However, the degradation of Pt species leads to poor durability of catalysts, limiting their applications in PEMFCs. Herein, a Janus heterostructure is designed for high durability ORR in acidic media. The Janus heterostructure composes of crystalline platinum and cassiterite tin oxide nanoparticles with carbon support (J-Pt@SnO2/C). Based on the synchrotron fine structure analysis and electrochemical investigation, the crystalline reconstruction and charge redistribution at the interface of Janus structure are revealed. The tightly coupled interface could optimize the valance states of Pt and the adsorption/desorption of oxygenated intermediates. As a result, the J-Pt@SnO2/C catalyst possesses distinguishing long-term stability during the accelerated durability test without obvious degradation after 40000 cycles and keeps the majority of activity after 70000 cycles. Meanwhile, the catalyst exhibits outstanding activity with half-wave potential at 0.905V and a mass activity of 0.355AmgPt -1 (2.7 times higher than Pt/C). The approach of the Janus catalyst paves an avenue for designing highly efficient and stable Pt-based ORR catalyst in the future implementation.

Acoustic process monitoring during the laser beam welding of stainless-steel foils using an adjustable ring mode laser beam source

Electrification of the mobility sector is vital to meet the targets for reducing greenhouse gas emissions. Besides battery-based mobility solutions, polymer electrolyte membrane fuel cells (PEMFCs) are a promising technology for electrifying drive trains, especially in heavy-duty applications, such as maritime or logistics. Bipolar plates, a key component of PEMFCs, can consist of two stainless-steel foils that must be welded to be gas-tight. In order to join the two metal foils, laser beam welding is the state-of-the-art technology. Current challenges include process instabilities at higher welding speeds, such as the humping effect, which can cause weld seam imperfections. Therefore, applying sensors for laser beam welding is a promising approach to monitor the welding process. AISI 316L foils were welded within the scope of this work with various process parameters using an adjustable ring mode laser beam source. Additionally, an optical microphone was used as a process monitoring system. By applying different parameter settings and due to the introduction of artificial faults, weld seam defects, such as a burn-through or a gap, were induced. After utilizing a noise reduction algorithm for the acoustic signals, numerous features in the time and frequency domains were extracted, with which multiple machine learning algorithms were trained and compared concerning their performance. A light gradient boosting machine was identified as a suitable machine learning model for weld seam classification. Finally, hyperparameter tuning was conducted, which resulted in a cross-validation accuracy of 94.78%, depending on the quality categories considered.

PVD Coatings for Lightweight Bipolar Plates

Bipolar plates are one of the main components of proton exchange membrane fuel cells (PEMFCs). Their functions include distributing reactants, supporting the cell, and conducting heat and electricity. They account for a significant proportion of the fuel cell stack’s weight and volume. The main materials currently used for bipolar plates are graphite and stainless steel. Aluminium has a much lower density than steel and is easier to form than both steel and graphite. Its use, therefore, would allow fuel cells with higher power densities but is hindered due to it being prone to corrosion. This work focused on the development of corrosion-resistant and conductive coatings to address this issue. Carbon coatings with Ti and Cr adhesion layers were deposited on aluminium substrates using closed-field unbalanced magnetron sputtering. These coatings were tested for corrosion properties and performance on the cathode side of a single-cell fuel cell. Coated aluminium samples were also tested for their ability to maintain their corrosion protection after being formed. Coating with a Cr adhesion layer outperformed that with a Ti adhesion layer in both forming and fuel cell tests, demonstrating much lower performance degradation after accelerated stress testing.

Energy efficiency analysis of ammonia-fueled power systems for vehicles considering residual heat recovery

Ammonia shows great potential as a zero-carbon fuel for vehicles. However, both the internal combustion engine (ICE) and the proton exchange membrane fuel cell (PEMFC), the currently available vehicle engines, require hydrogen decomposed from ammonia. On-board hydrogen production is an energy-intensive process that significantly reduces system efficiency. Therefore, energy recovery from residual heat is essential to promote overall efficiency, but ICE and FC require different amounts of hydrogen, and produce residual heat of dissimilar quality and quantity. To thoroughly understand the relationships among system configuration, rate of residual heat recovery and system efficiency, this paper takes three typical ammonia-fueled power systems, which employs only ICE, only PEMFC and both ICE and PEMFC as engine(s), respectively, as examples to set up system efficiency model and conduct simulation under various operating conditions. Results show there is a mismatch between the produced residual heat and the heat required for ammonia decomposition for systems using only ICE or PEMFC. For system using both PEMFC and ICE, the residual heat can be recovered to a maximum extent by way of parameters matching and dynamic power management between engines. This system has the highest efficiency and widest high efficiency region among the three analyzed typical configurations.

Development of optimal energy management strategy for proton exchange membrane fuel cell-battery hybrid system for drone propulsion

Drones powered by fuel cells have been developed to ensure long flight distances. Due to the low dynamic responsiveness of proton exchange membrane fuel cell (PEMFC) systems, they must be integrated with batteries to fully meet the power demand profiles of drones. In this study, a dynamic model of a PEMFC-battery hybrid system for drone propulsion is developed in MATLAB-Simulink® to establish the optimal energy management strategy (EMS) for ensuring efficient and safe operation. The proposed PEMFC system comprises two modules of an open-cathode PEMFC stack, which are connected in parallel. To estimate the dynamic behavior and performance of PEMFC, one-dimensional dynamic model of PEMFC considering two-phase transport through the gas diffusion layer is developed and simulated. A zero-dimensional dynamic model of the battery was also developed based on an equivalent circuit model. The resulting PEMFC-battery hybrid system model was simulated to determine the power required for the propulsion of the drone according to a flight scenario comprising five phases: takeoff hover, climb, cruise, descent, and landing hover. Three different EMSs are developed and simulated to define the optimal one for the PEMFC-battery hybrid system by comparing the total hydrogen consumption and the final SOC of the battery As a result, the EMS that equally splits the required power between two PEMFCs exhibits the lowest hydrogen consumption during the flight simulation. This study helps provide the optimal system design and control scheme of drones powered by fuel cells.

Unlocking the potentials using humidifier-dehumidifier for proton exchange membrane fuel cell waste heat recovery

This study addresses the dual challenges of waste heat dissipation and operational longevity degradation in proton exchange membrane fuel cells (PEMFCs) by proposing a novel hybrid system that integrates PEMFC with a humidifier-dehumidifier (HDH) unit. The primary objective is to enhance the energy efficiency and sustainability of PEMFC systems by leveraging waste heat for freshwater generation. A comprehensive mathematical model based on thermodynamic and electrochemical principles is developed to capture the system’s inherent irreversible losses. The performance metrics, including power density, energy efficiency, and exergy efficiency, are evaluated through systematic computational simulations. The proposed PEMFC/HDH hybrid system achieves a maximum power density of 4.8292 W cm-2 and an energy efficiency of 17.30%, showing a 1.48% improvement over standalone PEMFC systems. Parametric studies reveal that optimizing operating pressure significantly enhances system performance, while factors such as increased PEM thickness and thermodynamic loss composite parameter hinder it. Local sensitivity analysis identifies PEM thickness as the most critical parameter affecting performance. This research pioneers the integration of PEMFC and HDH for cogeneration, offering a viable path for performance enhancement and efficient waste heat utilization. The findings contribute to the strategic design and operational regulation of PEMFC-based hybrid systems for sustainable energy solutions.

Two-Phase Fluid Dynamics in Proton Exchange Membrane Fuel Cells: Counter-Flow Liquid Inlets and Gas Outlets at the Electrolyte-Cathode Interface

Understanding the counter-flow of liquid inlet and gas outlet at the interface between the electrolyte and cathode gas diffusion layer (GDL) is crucial for water management in proton exchange membrane fuel cells. Existing studies typically overlook air outlets and assume a fixed liquid inlet direction. This study uses a volume of fluid method to model two-phase interactions in a T-shaped GDL and gas channel (GC) assembly, with GDL geometry derived from nano-computer tomography. Considering potential electrode deformations, such as local cracks and blockages, this research investigates the impact of the size and shape of liquid invasion on the liquid-gas behavior in the cathode GDL and GC using five liquid injection configurations. Simulations also incorporate GDL gas outlets, integrating them with a tailored liquid inlet setup. Results show that the injection site and configuration significantly affect water behavior in the GDL, affecting saturation, stabilization, and breakthrough, followed by drainage in the GCs. Comparisons of simulations with and without air outflow show distinct counter-flow interactions, highlighting variations in water distribution and discrepancies in two-phase transport across the GCs.