PEM Fuel Cell Performance Research Articles

A parametric numerical study on the performance of polymer electrolyte membrane fuel cell with intermediate‐blocked interdigitated flow field designs

AbstractFlow field design is crucial for achieving higher performance in polymer electrolyte membrane fuel cells (PEMFCs). This study uses a two‐phase, multi‐component, and three‐dimensional model to simulate the performance of PEMFCs that use interdigitated flow field design with intermediate blocks on the cathode side. A detailed parametric study is presented to investigate the effects of various geometric and operational parameters. Of the parameters studied, inlet mass flow rate, relative humidity, and rib width had the greatest impact on cell performance. The results show that increasing the cathode stoichiometric ratio resulted in higher fuel cell performance for blocked interdigitated designs compared to parallel designs. In addition, using cathode channels with higher height values resulted in lower PEMFC performance for all flow fields. Higher values of rib/channel width ratio resulted in lower cell performance due to liquid water accumulation in the rib regions. However, at higher rib/channel width ratios, the positive effect of using interdigitated flow designs was more pronounced. Moreover, at a low relative humidity of RH = 25%, a 10.4% higher performance was obtained for the interdigitated type II compared to cases with RH = 100%, due to more effective over‐rib convection and higher water removal.

Thermal performance assessment of a low power proton exchange membrane fuel cell with various air-cooled channels

One of the important parts of the air-cooled fuel cell is the cathode, the design of which is of great importance and should be such that the temperature and current density are as uniform as possible. This study considers two different configurations (circular and square) with various arrangements (1 × 5, 2 × 10, 3 × 15 and 4 × 20) for the cooling channels. The focus of this study is on temperature distribution, power density and entropy generation in an air-cooled fuel cell. Therefore, the aim of this study is to compare different air-cooled channels on the PEM fuel cell performance. The results show that in terms of uniformity of temperature distribution and minimum temperature, using a circular channel is preferable to a square channel, but it has the lowest power density and the highest entropy generation. The results show that under different environmental conditions, it is possible to control the thermal management in the fuel cell by choosing the number of different channels.

Cross flow and distribution characteristics in automobile polymer electrolyte membrane fuel cells: A three-dimensional full-scale modeling study

Ultrahigh power density is of primary importance to next-generation polymer electrolyte membrane fuel cell (PEMFC) for commercialization, which demands an in-depth insight into the intricate multi-physics transports, particularly for large-size PEMFCs in automobile application. In this study, a three-dimensional two-phase model is extended to study an automobile fuel cell with the active area of 366.6 cm2, including full morphologies of metallic bipolar plate, flow field, and distribution zones for hydrogen, air and coolant flow. It is found that the cross flow inside membrane electrode assembly under the rib between two adjacent channels promoted by the distribution zone can effectively mitigate local oxygen starvation and water flooding, increasing PEMFC performance at high current density, in comparison with conventional single-channel or no-dot-matrix models. Theoretical analysis indicates that the dot matrix distribution zone induces a larger pressure gradient and hence the cross flow than the commonly-used channel & rib distribution zones. Additionally, the counter-flow configuration has a higher cell performance and more uniform current density than the co-flow one due to internal humidification. When the internal humidification effect is weak, for example, in anode/cathode gas co-flow configuration, coolant flow direction becomes more important for the temperature profile and prevent severe dehydration.

Electrochemical characteristics and damage behaviour of DLC-coated 316L stainless steel for metallic bipolar plates of PEMFCs

ABSTRACT A diamond-like carbon (DLC) coating was deposited on the surface of 316L stainless steel using the arc ion plating (AIP) method to improve the life and efficiency of the metallic bipolar plate for polymer electrolyte membrane fuel cells (PEMFCs). The electrochemical characteristics and damage behaviour were investigated in an accelerating solution simulating the PEMFCs operation environment. A result of the experiment showed the corrosion current density of all specimens with DLC coatings was lower than that of the base metal. However, when the thickness of the DLC coating was 0.3 and 0.5 μm, the corrosion resistance was lower than that of the base metal. This is thought to be because defects on the coating surface result in crevice corrosion of the gap between the coating layer and the intermediate layer or between the coating layer and the base metal, further accelerating corrosion.

Cerium-Based Perovskite Mixed Metal Oxide as the Radical Scavenger for PEM Fuel Cells Operating under Low Humidity Conditions.

When the polymer electrolyte membrane fuel cell (PEMFC) is operated under low humidity, the proton conductivity decreases due to membrane dehydration, causing adverse effects on fuel cell performance. Introducing appropriate additives to the membrane and catalyst layer to prevent membrane degradation at low humidity brings significant performance improvements to proton exchange membrane fuel cells. We developed a perovskite-structured multi-metal oxide Ce0.667Zr0.05Ti0.95O3-δ (CZTO) with high radical scavenging properties and good structural stability. The nanostructured ceramic CZTO is introduced into the membrane and cathode catalyst layer to improve the durability of the membrane electrode assembly. The Nafion-CZTO membrane exhibited maximum power densities of 1298 and 519 mW cm-2 at 100 and 20% relative humidity, respectively. The improved performance of Nafion-CZTO membranes over commercial Nafion membranes is due to the high proton conductivity and better radical scavenging properties of the CZTO additive. In addition, the expected positive effects of applying CZTO additives to the catalyst layer are verified by low charge transfer resistance and high electrochemical surface activity of the CZTO catalyst through electrochemical impedance spectroscopy and electrochemical surface area analyses.

Investigating the effect of solvent composition on ink structure and crack formation in polymer electrolyte membrane fuel cell catalyst layers

To improve the performance of polymer electrolyte membrane fuel cells (PEMFCs), controlling the microstructure of the membrane electrode assembly (MEA) catalyst layer is crucial. Ink design, which includes a catalyst, an ionomer, and a solvent, serves as the starting point for controlling the microstructure of the catalyst layer. However, there is a significant lack of understanding of the ink structure required for this purpose. In this study, we investigated the effect of the solvent, a key component that determines the ink structure. The ink comprises 20 wt% Pt/C, short-side-chain (SSC) Aquivion ionomer, and a solvent mixture of 1-propanol (NPA) and water. Three types of inks with different compositions of NPA and water are manufactured, and their stability and rheological properties were measured to infer and compare the ink structures. Furthermore, the crack characteristics of the catalyst layer were compared by directly coating the ink onto the electrolyte membrane using the doctor-blade method. In the ink with a high water content, we observed a gel-like elastic behavior dominated by network structures formed by ionomers adsorbed between catalyst particles. In contrast, the ink with a high NPA content exhibited a liquid-like viscous behavior dominated by well-dispersed catalyst particles and ionomers. These properties of the inks directly influence the crack formation characteristics after coating. Specifically, the strong liquid properties of the NPA-rich ink were found to suppress crack formation in the catalyst layer. These findings provide important insights into how the solvent composition affects ink structure and how it, in turn, influences crack formation in the catalyst layer, which can help optimize the ink design to improve the performance of PEMFCs.

(Digital Presentation) The Utilization of Platinum Catalysts Deposited on Carbon Support Synthesized from Coffee Grounds in a Polymer Electrolyte Membrane Fuel Cell

In this study, carbon support material, derived from coffee grounds was used in the preparation of Pt catalysts for polymer electrolyte membrane fuel cell (PEMFC) application. The carbon material was synthesized using ZnCl2 activated pyrolysis method and the Pt nanoparticles were deposited onto carbon support by two methods: using ethylene glycol or hydrogen as a reducing agent. Synthesis of the catalyst materials on coffee ground derived carbon was successful and produced materials with desirable physical and electrochemical properties. Synthesis through the ethylene glycol reduction method, with catalyst material deposited on the gas diffusion layers and additional Nafion layers, produced the most catalytically active material with an electrochemically active surface area value of 63 mPt 2 gPt −1 and catalytic performance of: current density was 0.56 A cm−2 at 700 mV and maximum power density was 0.56 W cm−2. Methods of boosting PEMFC performance through deposition of catalyst material and adding additional Nafion layers were effective and assisted in increasing the overall PEMFC performance.

Analysis and Experimental Verification of the Sealing Performance of PEM Fuel Cell Based on Fractal Theory

Aiming to accurately predict the leakage rate of the sealing interface, this work proposes a two-dimensional finite element model of a proton exchange membrane fuel cell, which includes the microscopic surface morphology and the asperity contact process of the components. First of all, we constructed the surface morphology of the seal by the two-dimensional W-M (Weierstrass–Mandelbrot) fractal function and explored the influence of fractal dimension (D) and scale parameter (G) on the surface profile. Furthermore, the finite element method and Poiseuille fluid theory were adopted to obtain the deformation variables of the asperity under different clamping pressures and leakage rates. Moreover, we quantitatively analyzed the impact of surface roughness on the clamping pressure and leakage rate. It was found that both the surface amplitude and surface roughness are positively correlated with G and negatively correlated with D. Surface morphology is proportional to D but has no relationship with G. Additionally, the deformation asperity decreases exponentially with growing clamping pressure, and the leakage rate is consistent with the experimental values at a clamping pressure of 0.54 MPa. With the same leakage rate, when the seal surface roughness value is less than 1 μm, a doubled roughness value leads to an increase of 31% in the clamping pressure. In contrast, when the surface roughness of the seal is greater than 1 μm, a doubled roughness value induces an increase of 50% in the corresponding clamping pressure.

Improving the Performance of PEM Fuel Cells: Form a Patterned Hydrophobic Catalyst Layer

In this study, we report a high-performance patterned hydrophobic catalyst layer suitable for efficient PEM fuel cells, thanks to alternating hydrophobic channels. Using the shadow mask spraying process, we produced a layer of dot-array and linear hydrophobic patterns on the ordinary cathode catalyst layer. The alternating hydrophobic channels enhance the transport of liquid water/air on the catalyst layer surface and improve the performance of the proton exchange membrane fuel cell. The performance of cells with dot-array hydrophobic catalyst layer (DHCL), linear hydrophobic catalyst layer (LHCL), and surface hydrophobic catalyst layer (SHCL) was compared with that of the ordinary catalyst layer (OCL). Their performance was characterized by in situ electrochemical methods such as electrochemical impedance spectroscopy and polarization curve. The results show that the output power of LHCL is 0.14 W higher than that of OCL, which is approximately 49% improvement. A stable water/gas channel is formed on the cathode catalyst layer surface, so that the mass transfer can be continuously and stably carried out. This work provides a new idea for the water management in fuel cells.

Effective single web–structured electrode for high membrane electrode assembly performance in polymer electrolyte membrane fuel cell

To achieve a sustainable society, CO2 emissions must be reduced and efficiency of energy systems must be enhanced. The polymer electrolyte membrane fuel cell (PEMFC) has zero CO2 emissions and high effectiveness for various applications. A well-designed membrane electrolyte assembly (MEA) composed of electrode layers of effective materials and structure can alter the performance and durability of PEMFC. We demonstrate an efficient electrode deposition method through a well-designed carbon single web with a porous 3D web structure that can be commercially adopted. To achieve excellent electrochemical properties, active Pt nanoparticles are controlled by a nanoglue effect on a highly graphitized carbon surface. The developed MEA exhibits a notable maximum power density of 1082 mW/cm2 at 80°C, H2/air, 50% RH, and 1.8 atm; low cathode loading of 0.1 mgPt/cm2; and catalytic performance decays of only 23.18 and 13.42% under commercial-based durability protocols, respectively, thereby achieving all desirables for commercial applications.

Effect of the high oxygen excess ratio design on the performance of air-cooling polymer electrolyte membrane fuel cells for unmanned aerial vehicles

Oxygen excess ratio (OER) is a key parameter that affects output power and operating current density of air-cooling polymer electrolyte membrane fuel cells (PEMFCs). In this work, the design method and performance model of air-cooling PEMFCs for UAVs with high OER are proposed. The high OER is realized by using high-speed airflow behind propeller to feed PEMFC cathode. The effect of high OER on the PEMFC performance is investigated by measuring OER and the output power of PEMFC. The test results indicate that the high OER design can further release the performance potential of the PEMFC constrained by heat dissipation while discarding the parasitic power caused by cooling fans. Compared with current PEMFC with low OER by using cooling fans, the temperature distribution variation of PEMFC stack is reduced by 29.8% and the voltage consistency of the single cell at high current density is doubled. The PEMFC with the high OER design exhibits the “current jump” effect, the continuous operating current of PEMFC is increased by 25.0%. The PEMFC net power is increased from 1070 W to 1320 W, and the power density is also increased by 67.8%. Such results provide good reference values for the current PEMFC-powered propulsion system.

In-situ visualization of cathode flow channel in polymer electrolyte membrane fuel cell: Effect of GDL degradation

Polymer electrolyte membrane fuel cells (PEMFCs) are used in various fields, but their lifetime should be considered for commercial applications. The degradation of their gas diffusion layer (GDL), which enables fuel diffusion and water management, can reduce the performance and accelerate the degradation of other components. This study investigates the effect of GDL degradation on in-situ flow characteristics in cathode flow channels. A special cell is designed to visualize in-situ two-phase flows in the cathode flow channel with a high-speed camera. As the GDL degrades, the flow pattern changes from dropwise to slug and annular flows. Moreover, the amount of residual liquid after one water discharge cycle increases as the GDL deteriorates. These changes in the flow patterns and remaining liquid can disrupt the fuel supply to chemical reaction sites and degrade PEMFC performance.

Hybrid PEM Fuel Cell Power Plants Fuelled by Hydrogen for Improving Sustainability in Shipping: State of the Art and Review on Active Projects

The interest in hybrid polymer electrolyte membrane fuel cells (PEMFC) fuelled by hydrogen in shipping has seen an unprecedented growth in the last years, as it could allow zero-emission navigation. However, technical, safety, and regulatory barriers in PEMFC ship design and operation are hampering the use of such systems on a large scale. While several studies analyse these aspects, a comprehensive and up-to-date overview on hydrogen PEMFCs for shipping is missing. Starting from the survey of past/ongoing projects on FCs in shipping, this paper presents an extensive review on maritime hydrogen PEMFCs, outlining the state of the art and future trends for hydrogen storage and bunkering, powertrain, and regulations. In addition to the need for a clear regulatory framework, future studies should investigate the development of an efficient fuel supply chain and bunkering facilities ashore. As for the onboard power system, health-conscious energy management, low-temperature heat recovery, and advancements in fuel processing have emerged as hot research topics.

Influence of liquid water accumulation on the impedance of a PEM fuel cell operating in dead end mode: Physical modeling and experimental validation

The dead-end mode operation of a PEM fuel cell reduces the reactants consumption and the system’s complexity, but also decreases its performance due to the accumulation of liquid water, which must be purged periodically. Despite extensive use of the EIS technique in studying PEM fuel cells’ internal processes, the inherently transient nature of dead-end mode operation has challenged the application and interpretation of this technique. In this paper, a novel analytical model is proposed to physically investigate the effect of liquid water accumulation on the impedance of a PEM fuel cell in dead-end mode operation. The model is well validated against experimental polarization curves and impedance diagrams in various operating conditions by employing a two-step fitting procedure. The findings of the model indicate the constant presence of a large amount of liquid water in the fuel cell due to the dead-end operation. Additionally, the buildup of liquid water reduces the active area of the catalyst layer and the effective oxygen diffusion coefficient in GDL, increasing both the charge and mass transfer resistances. Finally, with its low computational cost, the developed analytical model can provide a suitable framework for purposes such as fault diagnosis and degradation prognosis.

Non-Conventional Hybrid Microporous Layers for Enhanced Performance and Durability of PEM Fuel Cells

In this work, novel microporous layers (MPLs) were developed based on fluorinated ethylene propylene (FEP), as a hydrophobic agent, and carboxymethylcellulose (CMC), as a wettability modulator and rheology controller for the inks, which were deposited onto pre-hydrophobized macroporous gas diffusion layers (GDLs). Higher CMC amounts led to higher dynamic viscosities of the inks, which induced the formation of a more compact and less cracked MPL surface. Different concentrations of CMC were tested and the experimental measurements showed a threshold limit pointing out an optimal composition that positively affected the electrochemical performances at medium-low relative humidity (RH), which is important to mitigate the need of saturating inlet gases. Durability of the best performing samples was assessed by means of an ad hoc developed accelerated stress test (AST) and compared to one of the conventional FEP-based GDMs. It was found that a lower decrement of both the output power density and the overall cell efficiency can be obtained upon the ASTs with the novel samples.

Pt‐Anchored‐Zirconium Phosphate Nanoplates as High‐Durable Carbon‐Free Oxygen Reduction Reaction Electrocatalyst for PEM Fuel Cell Applications

AbstractCommercially available platinum‐supported carbon (Pt/C) catalysts are the most widely used oxygen reduction reaction (ORR) electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs). However, inadequate active triple‐phase boundary formation and carbon oxidation in Pt/C during PEMFC operation shorten its lifetime and efficiency. In this direction, a new class of carbon‐free electrocatalysts for ORR is prepared by dispersing Pt nanoparticles on ZrP (Zirconium phosphates) nanoplates. In one case (ZrP@Pt), the Pt nanoparticles are found to be closely distributed and completely covering the ZrP nanoplates, whereas in the second case (Pt/ZrP), the Pt nanoparticles selectively restrict dispersion along the edges of the support. ZrP as the support displays an intrinsic proton conductivity of ≈0.5 × 10−4 S cm−1 at 70 °C, with an activation energy (Ea) of 0.19 eV. Pt/ZrP shows better durability after 3000 start‐stop cycles. The mass activity of Pt/ZrP is increased by 4.6 times compared to Pt/C, which exhibits a loss in mass activity by 1.37 times. The single‐cell level validation of ZrP@Pt, Pt/ZrP, and Pt/C as the electrocatalysts in PEMFC at an operating potential of 0.60 V shows the achievable current densities of 0.600, 0.890, and 0.890 A cm−2.

Critical investigation of microchannel design effect on thermal performances of a pem fuel cell

A major challenge for improving the characteristics of fuel cells is to obtain uniform tempera-ture distribution during its operation, in which a major part of hydrogen chemical energy is converted to heat. If not properly exhausted, this exothermic chemical reaction causes overheat-ing in the polymer electrolyte membrane fuel cells (PEMFCs), leading to a reduction in their performance. Hence, analyzing different techniques for PEMFCs cooling may be necessary for this kind of energy systems. In this study, four microchannel design effect on aluminum oxide (Al2O3) nanofluids thermal behavior in cooling plates with 1400×1800 mm2 was investigated using computational fluid dynamic (CFD) simulation. The performances of proposed micro-channel designs were evaluated in terms of maximum and uniformity temperature. The sug-gested study has been validated by available published results from previous research studies. The obtained results depicted that the maximum temperatures have been 305.3K and 305.5K for S- character flow field and two stages coolant flow field microchannel designs, respectively. The results revealed that the multi-flow plate designs might greatly enhance the performance of PEMFCs in terms of temperature distribution in the cooling plate when compared to standard flow field designs. Another important finding was that the two stages microchannel and S-de-sign are more thermal stable compared with other microchannels.

Comparison of PEMFC performance with parallel serpentine and parallel serpentine-baffled flow fields under various operating and geometrical conditions; a parametric study

Optimal flow channel design of a fuel cell is crucial to further improve the performance of polymer electrolyte membrane fuel cell (PEMFC). In this work, a comprehensive parametric study was conducted to analyze the performance of a PEMFC with conventional parallel serpentine flow fields (PSFF) and parallel serpentine-baffled flow fields (PSBFF). A three-dimensional two-phase computational fluid dynamics model was used to numerically simulate the fuel cell performance. The effects of operating parameters such as pressure, temperature, and stoichiometric ratio, as well as the geometric parameters of channel height to channel width ratio and rib width to channel width ratio for both flow fields on fuel cell performance were investigated. The results show that as pressure, temperature, and stoichiometric ratio increase, cell performance increases for both flow fields, with a more substantial rate of improvement for the PSBFF design. A 16.1% improvement in cell performance at an operating pressure of 1 atm, a 19.9% improvement at a cell temperature of 70 °C, and a 16.1% improvement at a stoichiometric ratio of 2 were obtained when PSBFF was used instead of PSFF. By increasing the channel height and rib width, the cell performance for PSBFF remains almost constant due to the improved forced convection of the gas mixture and the reduction in concentration loss, while the cell performance for PSFF decreases significantly. At the largest channel height to channel width ratio of 1.5 and rib width to channel width ratio of 1.315 studied in this work, an improvement in cell performance of 53.3% and 58.5%, respectively, was achieved when PSBFF was used instead of PSFF. In addition, PSBFF was more effective in removing water from the porous zones than PSFF under all conditions.

Effect of alcohol content on the ionomer adsorption of polymer electrolyte membrane fuel cell catalysts

Catalyst layers (CL) composed of catalyst composites and an ionomer are key components in polymer electrolyte membrane fuel cells (PEMFCs). In particular, the preparation conditions of the CL, starting from the dispersion of the catalyst composite dispersion with an ionomer, largely affect the PEMFC performance. In this study, the effects of alcohol content in the dispersion solvent were investigated using two binary mixtures composed of water and ethanol. In addition, Pt-loaded carbon black (CB) and Pt-loaded polymer-wrapped CB were used as the catalyst composites to study the effects of the alcohol contents on the interaction between ionomer and surface of the carbon supports. The CL prepared using the water-rich (80 wt% water) solvent achieved a higher PEMFC performance compared to that using the alcohol-rich (13 wt% water) solvent, which is ascribed to the stronger interaction between the ionomer and CB surface under water-rich conditions. Using the polymer-wrapped CB, the difference of the PEMFC performance between the CLs from the water-rich and alcohol-rich dispersions was minimal because of the comparable interaction between the ionomer and wrapping polymer surface in both solvents. Therefore, the control of the interaction between the ionomer and catalyst composites is crucial to controlling the PEMFC performance.

Polymer Electrolyte Membranes Containing Functionalized Organic/Inorganic Composite for Polymer Electrolyte Membrane Fuel Cell Applications.

To mitigate the dependence on fossil fuels and the associated global warming issues, numerous studies have focused on the development of eco-friendly energy conversion devices such as polymer electrolyte membrane fuel cells (PEMFCs) that directly convert chemical energy into electrical energy. As one of the key components in PEMFCs, polymer electrolyte membranes (PEMs) should have high proton conductivity and outstanding physicochemical stability during operation. Although the perfluorinated sulfonic acid (PFSA)-based PEMs and some of the hydrocarbon-based PEMs composed of rationally designed polymer structures are found to meet these criteria, there is an ongoing and pressing need to improve and fine-tune these further, to be useful in practical PEMFC operation. Incorporation of organic/inorganic fillers into the polymer matrix is one of the methods shown to be effective for controlling target PEM properties including thermal stability, mechanical properties, and physical stability, as well as proton conductivity. Functionalization of organic/inorganic fillers is critical to optimize the filler efficiency and dispersion, thus resulting in significant improvements to PEM properties. This review focused on the structural engineering of functionalized carbon and silica-based fillers and comparisons of the resulting PEM properties. Newly constructed composite membranes were compared to composite membrane containing non-functionalized fillers or pure polymer matrix membrane without fillers.