Fuel Cell Performance Research Articles

The effect of pin-type flow field plate design on the current distribution in a H2-fed polymer electrolyte fuel cell

The flow field plate (FFP) design is a key factor for enhancing the electrochemical performance of Polymer Electrolyte Fuel Cells (PEFCs) through optimal reactants’ distribution, low-pressure drops, and efficient water removal. The effect of geometrical features of the pin-type FFP design on the electrochemical performance of a 48 cm2 H2-fed Fuel Cell (FC) was assessed through polarization curves recording and current and temperature distribution maps along the electrode active area. The study was performed by changing excess air stoichiometry and cathode relative humidity (RH). Low-pressure drops were measured using pin-type FFPs; regardless of geometrical features, they were one order of magnitude lower than those of a single-channel serpentine FFP. Channel width and number of pins greatly influenced the current distribution along the active area and, consequently, the electrochemical performance of FCs. In particular, the best electrochemical performance was reached at air stoichiometry 4 and cathode RH = 100 % by using FFP with the highest coverage factor (65 %) and the lowest channel width (1 mm). Current distribution maps demonstrated that this FFP geometry led to an almost homogeneous current distribution and efficient water removal also at high current density values. On the contrary, low coverage factor (45 %) and high channel width led to worse electrochemical performances due to an uneven reactants distribution and an inefficient water removal, causing cell flooding.

Effects of Co3O4 modified with MoS2 on microbial fuel cells performance

In this study, Co3O4@MoS2 is prepared as anodic catalytic material for microbial fuel cells (MFCs). As the mass fraction of MoS2 is 20%, the best performance of Co3O4@MoS2 composite catalytic material is achieved, and the addition of MoS2 enhances both the electrical conductivity and catalytic performance of the composite catalyst. Through the structural characterization of Co3O4@MoS2 composite catalytic material, nanorod-like Co3O4 and lamellar MoS2 interweaved and stacked each other, and the agglomeration of Co3O4 is weakened. Among the four groups of single-chamber MFCs constructed, the Co3O4@MoS2-MFC shows the best power production performance with a maximum stable output voltage of to 539 mV and a maximum power density of up to 2221 mW/m2. Additionally, the ammonia nitrogen removal rate of the MFCs loaded with catalysts is enhanced by about 10% compared with the blank carbon cloth MFC. Overall, the findings suggest that Co3O4@MoS2 composite catalysts can significantly improve the performance of MFCs, making them more effective for both energy production and wastewater treatment.

An investigation into the effect of anode platinum loading on Direct Methanol Fuel Cell performance

An investigation into the effect of anode platinum loading on Direct Methanol Fuel Cell performance

Improving the performance and long-term durability of high-temperature PEMFCs: A polyvinylpyrrolidone grafting modification strategy of polybenzimidazole membrane

This study introduces an innovative approach to graft Polyvinylpyrrolidone (PVP) onto Polybenzimidazole (PBI) to synthesise Proton Exchange Membranes (PEMs) with high performance and durability. As a widely used hydrophilic polymer in industry, PVP can add numerous nitrogen-containing functional groups to the membrane to enhance its phosphoric acid (PA) binding ability. In this work, Polybenzimidazole-graft-polyvinylpyrrolidone (PVP-g-PBI) polymers with varying grafting degrees were synthesized and tested to investigate the impact of the grafting modification on the membrane's proton conductivity, thermal properties, and electrochemical performance. With the introduction of PVP side chains, the fuel cell showed enhanced PA uptake and substantial improvements in peak power density. Notably, PBI-g-PVP membranes with a grafting degree of 22.4 % achieved a peak power density enhancement up to 1312 mW cm⁻2 at 160 °C, a 59.6 % increase over pristine PBI membranes. Due to the increased PA binding sites in the membrane, the PBI-g-PVP PEMs exhibit better PA adsorption ability and long-term durability than pristine membranes. The accelerated stress test (AST) demonstrated that the PBI-g-PVP membranes maintain a peak power density of 1105 mW cm⁻2 after a 70-h test, equivalent to 183.9 % of the pristine PBI membrane. The improved fuel cell performance and durability of PBI-g-PVP PEMs underscore the potential of this grafting strategy.

Exploring the thermomechanical and dynamical mode switch transition of a reversible solid oxide cell

Reversible solid oxide cells (r-SOCs) are regarded as a solution form of clean energy generation towards a green hydrogen energy transition. However, during transportation, installation, and operation, they are required to withstand dynamic conditions as they face thermal, mechanical, and vibrational effects. Assessing the interplay of the thermomechanical and dynamical impacts on r-SOC materials during the mode-switch from electrolysis to fuel cell operation is the subject of this current comprehensive study. Advanced FEM-based homogenisation techniques have been harnessed in predicting and evaluating the detailed transients during static and dynamic loading. The intricate 3D thermal profiles throughout the transient reversible dual-modus operation from a typical r-SOC study have been derived using advanced image processing. Orthotropic material properties were incorporated into a unified macroscopic scale model by deriving the complex 3D microstructure geometry characteristics of the cell materials and component layers. The comprehensive thermomechanical and pre-stressed modal analysis results showed that the static and dynamic forces in fuel cell mode are more pronounced, whereas, in electrolysis operation, the dynamical behaviour highly depends on geometrical and operating conditions. Smaller component size shows higher natural frequencies and more intense vibration, leading to higher deformation attributed to complex mode shapes and reduced flexural rigidity. These insights are essential for optimizing r-SOC design parameters, enhancing their dynamic and structural reliability throughout their dual-mode operation lifespan.

Computational Fluid Dynamic Investigation of Local Flow-Field Conditions in Lab Polymer Electrolyte Membrane Fuel Cells to Identify Degradation Stressors and Performance Enhancers

The use of polymer electrolyte membrane (PEM) fuel cells as an alternative to internal combustion engines can significantly contribute to the decarbonization of the transport sector, especially for heavy-duty applications. However, degradation is still an issue for this type of component, affecting their durability and performance. In this scenario, a detailed analysis of the anodic and cathodic distributors’ flow-field geometry may help to identify some local stressors that trigger the degradation mechanism, such as local hot spots and reactants not having a uniform distribution. A computational fluid dynamic (CFD) methodology is able to provide a volumetric description of a PEM fuel cell so it can be a useful tool to better understand the physical phenomena that govern the component operations. In this work, the open-source simulation library openFuelCell2 is adopted for a detailed analysis of two different PEM fuel cells characterized by standard distributor geometries, namely a parallel channel geometry and a serpentine configuration. The library, based on the OpenFOAM code, has been extended with a novel implementation accounting for the catalytic activity reduction due to the platinum oxide (PtOx) formation occurring under certain particular conditions. The adopted methodology is firstly validated resorting to experimental data acquired for the two different fuel cell configurations. The analysis highlights that the PtOx formation leads to a reduction in the fuel cell performance reaching up to 60–80% when operating at high voltages. Then, the effect of the distributor geometries on the component performance is investigated by resorting to in-plane and through-plane physical quantity distribution, such as reactant concentration, pressure or velocity fields. While the parallel flow channel configuration shows some diffusion losses under the rib, the serpentine channel geometry configuration can achieve some local performance peaks thanks to the convective flow in the gas diffusion layer (GDL) driven by local pressure gradients. Furthermore, the local enhancement in terms of higher current density under the rib is associated with an effective heat removal due to the high thermal capacity of the bipolar plate, avoiding the generation of local hot spots.

Parametric Study of a Large Active Area PEM Fuel Cell using a MatLab-Simulink Model

A Matlab-Simulink based mathematical model and simulation method is developed by applying appropriate physics and electro-chemistry that adequately describes a proton exchange membrane fuel cell (PEMFC) system. The mathematical model is then simulated for a single low temperature PEMFC with a large, 350cm2, active area. The single cell’s performance was evaluated using different operating conditions and varying values of various crucial system parameters. The Matlab-Simulink model presented in this investigation is used to study various parameters’ effect such as the cell temperature from 50℃ to 90℃, inlet pressure, relative humidity (RH) from 70% to 90%, and the reactant stoichiometry ratio, on the cell performance. Comparison of polarization and power density curves were conducted between the model simulation and experimental data at 60℃ and at 65℃. Except for the higher current densities range (≥1.6 A/cm2), the simulation results match with the experimental results very well. The parametric study was used to determine the optimum value of various parameters. The fuel cell performance with the optimized parameter values show a good improvement using the developed MatLab-Simulink model.

Novel siliceous mesoporous phosphotungstic acid embedded chitosan/LSMM polymer membrane for direct methanol fuel cells

Direct Methanol Fuel Cells (DMFCs) research focuses on improving Proton Exchange Membranes (PEMs) to enhance ion exchange and proton conduction. Although Nafion® is stable both chemically and thermally, however it suffers methanol crossover. In this study, a novel composite PEM was introduced by blending chitosan (CS), hydrophilic surface modifying macromolecules (LSMM), and mesoporous siliceous phosphotungstic acid (mPTA-Si) at varying loadings. Notably, the CS/LSMM membrane with 0.25 wt% of mPTA-Si content and optimized hot pressing technique conditions (5 tonnes, 90 s and 135 °C) exhibited superior performance, with a proton conductivity of 0.097 S/cm and a power density of 60 mW/cm2. Additionally, properties such as tensile strength and ion exchange capacity surpassed those of pure CS by 14 % and 56.12 %, respectively. The unique characteristics of CS, mPTA, and LSMM collectively contributed to the promising attributes of the CS/LSMM/0.25mPTA-Si membrane for enhancing fuel cell performance.

High-performance imidazole-containing polymers for applications in high temperature polymer electrolyte membrane fuel cells

This work focuses on the development of high temperature polymer electrolyte membranes (HT-PEMs) as key materials for HT-PEM fuel cells (HT-PEMFCs). Recognizing the challenges associated with the phosphoric acid (PA) doped polybenzimidazole (PBI) membranes, including the use of carcinogenic monomers and complex synthesis procedures, this study aims to develop more cost-effective, readily synthesized, and high-performance alternatives. A series of superacid-catalyzed polyhydroxyalkylation reactions have been carefully designed between p-terphenyl and aldehydes bearing imidazole moieties, resulting in a new class of HT-PEMs. It is found that the chemical structure of aldehyde-substituted N-heterocycles significantly impacts the polymerization reaction. Specifically, the use of 1-methyl-2-imidazole-formaldehyde and 1H-imidazole-4-formaldehyde monomers leads to the formation of high-viscosity, rigid, and ether-free polymers, denoted as PTIm-a and PTIm-b. Membranes fabricated from these polymers, due to their pendent imidazole groups, exhibit an exceptional capacity for PA absorption. Notably, PTIm-a, carrying methylimidazole moieties, demonstrates a superior chemical stability by maintaining morphology and structural stability during 350 h of Fenton testing. After being immersed in 75 wt% PA at 40 °C, the PTIm-a membrane reaches a PA content of 152%, maintains a good tensile strength of 13.6 MPa, and exhibits a moderate conductivity of 50.2 mS cm−1 at 180 °C. Under H2/O2 operational conditions, a single cell based on the PTIm-a membrane attains a peak power density of 732 mW cm−2 at 180 °C without backpressure. Furthermore, the membrane demonstrates stable cycle stability over 173 h within 18 days at a current density of 200 mA cm−2, indicating its potential for practical application in HT-PEMFCs. This work highlights innovative strategies for the synthesis of advanced HT-PEMs, offering significant improvements in membrane properties and fuel cell performance, thus expanding the horizons of HT-PEMFC technology.

Role of Graphene-Silver Nanocomposite as Anode to Boost Single-Chamber Microbial Fuel Cell Performance

Role of Graphene-Silver Nanocomposite as Anode to Boost Single-Chamber Microbial Fuel Cell Performance

Effects of concentrated CO2 on the performance of a PBI/H3PO4 high temperature proton exchange membrane fuel cell

In this study, the impact of mimic reformate of formic acid decomposition on the anode polarization of HT-PEMFC is investigated under various operating conditions of the anode, including different concentrations of CO2, N2, CO, and humidification. Polarization curve and EIS measurements indicate that there is no significant difference (less than 5 mV when i < 0.4A/cm2) between the same concentrations of CO2 and N2 up to 75 vol%. No significant poisoning of the anode by CO2 (up to 75 vol%) has been observed, suggesting that the addition of concentrated CO2 acts more as a diluent than a poison. Upon separating the polarization effects, it is found that the oxygen reduction reaction (ORR) is a crucial step limiting the fuel cell performance, with cathodic activation losses reaching as high as 70 % at 0.8A/cm2. However, with 1 vol% CO in a H2/CO2 1/1 mixture, a significant poisoning effect on the fuel cell is observed. DRT (distribution of relaxation times) analyses reveal two peaks related to CO in high-frequency regions above 100 Hz associated with the anode polarization, with the peak integration being five times larger than in pure hydrogen. Humidification doesn't improve the voltage or mitigate CO poisoning. A one-dimensional flux model that includes the anode polarization is developed to analyze the polarizations for both cathode and anode under different concentrations of diluents, well describing the experimental results. When i < 0.8 A/cm2, the predicted values from the model closely match the measured values (within 5–10 mV). Calculations suggest that the anode polarization cannot be ignored, especially when the anode is fed with diluted gases.

Unraveling the Influence of Nafion Content on the Performance of Proton-Exchange Membrane Fuel Cells from the Perspective of Triple-Phase Boundary.

By combining molecular simulations and experimental measurements, the effect of the Nafion content on the performance of proton-exchange membrane fuel cells (PEMFCs) is explained from the perspective of the triple-phase boundary (TPB). The evaporation process of Nafion solvent is simulated on a triple-phase model to mimic the formation of the TPB, and the influence of the Nafion content on the TPB structure is investigated. When the Nafion content is 1.415 mg/m2, the coverages of Nafion on both Pt particles and the carbon carrier are saturated at 42.1% and 32.7%, respectively. With the increase of Nafion content, the amount of water molecules around Pt particles is increased, and the surrounding O2 content is decreased. The experimental PEMFC performance has confirmed such simulation results, which demonstrates a trend of enhancing first and then weakening with the increase of Nafion content and reaches a maximum with the Nafion content of 2.96 mg/m2. Therefore, the correlation between the structure of the TPB and the cell's efficiency has been established at a molecular level, enabling enhancements in the design of the TPB morphology and an increase in PEMFC efficiency.

Designing of low-temperature high performance semiconductor ionic fuel cells based on molten hydroxide percolation network

A low-temperature high performance semiconductor ionic membrane fuel cell (SIMFC) featuring a γ-Al2O3/NCAL symmetrical electrode and a ceria-based Li0.85Na0.15OH/Mg0.1Al0.2Ce0.7O2-δ (LNCMA) electrolyte has been designed. This device attains a maximum power density (MPD) of 1111 mW/cm2 and demonstrates stability for nearly 40 h at 550 ℃. Additionally, the system remains operational at 350 ℃, delivering an excellent MPD of 114 mW/cm2. The amazing research can be attributed to a molten network of hydroxide that serves as a highway for oxygen ion interface conduction, leading to an enhancement in the ionic conductivity and a reduction in ohmic impedance of the SIMFC. In the testing environment of this newly developed SIMFC device, the γ-Al2O3/NCAL electrode provides a protective effect on LiOH, enabling higher concentrations of molten LiOH to be retained and percolated into the electrolyte. Subsequently, the composite Li0.85Na0.15OH directly introduced into LNCMA melts and readily connects with LiOH from the anode, forming a molten network. As a result, the SIMFC, designed based on the concept of the molten hydroxide percolation network, achieves improved fuel cell performance and enables the operation of the SIMFC even at 350 ℃. This study showcases a convenient method for constructing a molten hydroxide percolation network, which provides the necessary low-temperature conductivity required for SIMFCs.

Numerical simulation analysis of composite flow field design on mass transfer in proton exchange membrane fuel cell

Bipolar plate flow field design is crucial for optimizing Proton Exchange Membrane Fuel Cell (PEMFC) performance. This study employs three-dimensional simulations and Computational Fluid Dynamics (CFD) methods to analyze and compare traditional Straight Parallel Flow Field (SPFF), Block Incorporated Flow Field (BIFF), Sub-channel Ribbed Flow Field (SRFF), and Combined Block and Sub-channel Flow Field (CBSFF). The findings indicate that CBSFF not only demonstrates superior oxygen distribution characteristics at high current densities but also shows improved uniformity in moisture and temperature distribution. In addition, the effect of the structural parameters of the CBSFF flow field on its performance has been investigated. In particular, at a voltage of 0.5 V, the net power of the CBSFF is increased by 18 percent compared with that of the SPFF when the height of the block, hb=0.5, and the height of the subchannel, hs=0.3, are used.

Investigating the Effects of the Physicochemical Properties of Cellulose-Derived Biocarbon on Direct Carbon Solid Oxide Fuel Cell Performance.

This paper presents a study of the characteristic effects of the physicochemical properties of microcrystalline cellulose and a series of biocarbon samples produced from this raw material through thermal conversion at temperatures ranging from 200 °C to 850 °C. Structural studies revealed that the biocarbon samples produced from cellulose had a relatively low degree of graphitization of the carbon and an isometric shape of the carbon particles. Based on thermal investigations using the differential thermal analysis/differential scanning calorimeter method, obtaining fully formed biocarbon samples from cellulose feedstock was possible at about 400 °C. The highest direct carbon solid oxide fuel cell (DC-SOFC) performance was found for biochar samples obtained via thermal treatment at 400-600 °C. The pyrolytic gases from cellulose decomposition had a considerable impact on the achieved current density and power density of the DC-SOFCs supplied by pure cellulose samples or biochars derived from cellulose feedstock at a lower temperature range of 200-400 °C. For the DC-SOFCs supplied by biochars synthesised at higher temperatures of 600-850 °C, the "shuttle delivery mechanism" had a substantial effect. The impact of the carbon oxide concentration in the anode or carbon bed was important for the performance of the DC-SOFCs. Carbon oxide oxidised at the anode to form carbon dioxide, which interacted with the carbon bed to form more carbon oxide. The application of biochar obtained from cellulose alone without an additional catalyst led to moderate electrochemical power output from the DC-SOFCs. The results show that catalysts for the reverse Boudouard reactions occurring in a biocarbon bed are critical to ensuring high performance and stable operation under electrical load, which is crucial for DC-SOFC development.

Biopolymeric electrolyte-based membrane on nanocrystalline cellulose/polyvinyl alcohol for a conceivable usage in proton exchange membrane fuel cell

In this study, we developed eco-friendly biopolymer electrolytes by blending nanocrystalline cellulose (NCC) with polyvinyl alcohol (PVA) and crosslinking them using glutaraldehyde. These membranes, denoted as NCC-x/PVA-y, were fabricated via the solution casting method. We thoroughly investigated the effects of different NCC to PVA ratios on various properties, including water uptake, swelling ratio, thermal and mechanical characteristics, proton conductivity, hydrogen permeation, and single Proton Exchange Membrane Fuel Cell (PEMFC) performances. Increasing the NCC concentration (ranging from 20 % to 60 %) led to enhanced surface roughness and compactness of ionic domains, resulting in improved dimensional stability and reduced hydrogen permeability across the membranes. Among the tested ratios, NCC-50/PVA-50 exhibited the highest proton conductivity, measuring 0.3 × 10−2 S cm−1. Notably, this ratio demonstrated a 60 % lower swelling ratio and lower hydrogen permeability (0.76 × 10−13 cm2/scmHg) compared to Nafion 117 (514 × 10−13 cm2/scmHg), indicating its superior performance. Furthermore, the NCC-50/PVA-50 membrane consistently maintained open-circuit voltages exceeding 0.9 V under all conditions, highlighting its effective proton transport capabilities and minimal fuel penetration. Density Functional Theory (DFT) analysis confirmed the successful cross-linking of NCC/PVA with glutaraldehyde, emphasizing its compatibility and potential for proton conductivity in PEMFC applications.

Surface modification of expanded polytetrafluoroethylene to reinforced composite membranes for proton exchange membrane fuel cells

The study reports on the fabrication of reinforced composite membranes via hydrophilic surface modification of highly hydrophobic and porous expanded polytetrafluoroethylene (ePTFE) using argon plasma treatment and silane coupling. These processes create amine end group, functionalized onto ePTFE surface, thus improving hydrophilicity. It enables impregnation of Nafion ionomer dissolved in a polar aprotic solvent as well as water/alcohol mixture solvent. The optimal silane coupling concentration is systematically determined and facilitates uniform grafting of amine-functionalized silane without the pore blockage of ePTFE. The resulting reinforced composite membranes show improved mechanical, chemical, and dimensional stabilities and comparable proton conductivity. However, their membrane ohmic resistance is slightly higher than that of a commercial Nafion membrane (N211), leading to slightly reduced fuel cell performance. Note, the processes of this study prove versatile, accommodating partially fluorinated polymers in aprotic polar solvents with ePTFE, holding its potential for creating alternative reinforced composite.

Performance and economic study of a novel high-efficiency PEMFC vehicle thermal management system applied for cold conditions

This paper proposes three different heating management systems, sysse (self priming thermal management system), syslow (low temperature thermal management system), and syssp (split flow thermal management system), which are mainly composed of PEMFC and heat pump subsystems. Simulations were conducted to compare the comprehensive performance of these systems under cold startup and cold operating conditions, and analyzed the effect of different factors on these three system. The results show that under the influence of cell stack parameters, compared to sysse and syslow, the syssp has an average power consumption reduction of 29.95 % and 20.94 %, with a maximum power reduction of 31.46 % and 27.61 %, the average range power increases by 35.09 % and 23.58 %, with a maximum range power increase of 107.53 % and 75.57 %, the average COPPEMFC (Coefficient of Performance of heating Proton Exchange Membrane Fuel Cell) increases by 0.56 and 0.37. Under the influence of heat pump parameters, the evaporating temperature has a larger impact on the performance gains of the syssp, while condensing temperature has a greater effect on power consumption, range power, and COP variations. Compared to sysse and syslow, the syssp can recover costs as quickly as 3.12 and 3.68 years.

Data-driven MPPT techniques for optimizing vehicular fuel cell performance in hybrid DC microgrid

This paper aims to apply data-driven maximum power point tracking (MPPT) techniques specifically tailored for fuel cell vehicle (FCV) supported hybrid DC microgrids to enhance the power harvesting capability of fuel cell (FC) stacks. Compared to existing MPPT techniques, the current study focuses on developing and evaluating data-driven approaches for maximum power extraction by dynamically determining the operating point of FC power sources through a Zeta converter. An in-depth analysis is conducted by considering parameters such as efficiency, tracking accuracy, response time, and robustness to variations in load demand and operating conditions. The performance results validate that the developed three-layer neural network (TNN)-based MPPT gives better performance findings than Gaussian process regression (GPR), support vector regression (SVR), decision tree regression (DTR), and bagging ensemble decision tree (BEDT). In the performance evaluation phase, a vehicular FC with a rating of 1.26 kW is designed and operated within the temperature range of 320 K to 343 K for hydrogen pressure values ranging from 1 bar to 1.8 bar. For these operational conditions, the prediction accuracy value of the proposed TNN method is 99.6% while the performance values GPR, SVR, DTR, and BEDT are 99%, 98.6%, 97.2%, and 96%. In addition, system efficiency is increased by 0.98%, 1.25%, 2.51%, and 3.02% compared to GPR, SVR, DTR, and BEDT, respectively.

Determination Of Two-Phase Flow Regimes Of A Condensing Water-Air Mixture In An Array Of Micro Channels

Proton exchange membrane (PEM) full cells (FCs) are a promising alternative to combustion engines for mobile applications. Their signature low operating temperature leads to the possible existence of product water in its liquid form. Liquid water formation and transport are important phenomena to understand and model in order to facilitate the development of new, more efficient PEMFCs. This contribution investigates the two-phase flow phenomena separately by introducing a gaseous air-vapor mixture into an optically accessible fuel cell flow plate with 14 parallel micro channels (confinement number Co = 7.3) and a carbon paper inlay representing the FC's gas diffusion layer and bringing it to the point of onset of condensation. Special care is taken to provide a controlled and reproducible air-vapor mixture with low pressure pulsation. One key feature of the experiment is that the flow plate used is designed to be as similar to a regular research fuel cell flow plate as possible, retaining its channel surface properties and electrical parameters. It can also be heated to a given temperature to mimic the fuel cell operating conditions. Therefore, the same plate can also be used in in-situ experiments in an operated fuel cell. An air mass flow rate of 500 - 1000 mLn / min with relative humidities of 75% - 95% at 65°C and 75°C was investigated. The emerging flow patterns were captured using a high-speed camera at 250 Hz and categorized using canonical two-phase flow regime nomenclature. It is shown that the present setup can produce the relevant two-phase flow patterns that can be found in operated fuel cells as reported by previous studies and is furthermore equipped to investigate flow states not easily reached with an operated fuel cell (e.g. flooded channels).