Development Of Fuel Cells Research Articles

(Invited) Optimized Conditioning and Performance of PEM Fuel Cell Stacks

The fuel cell market is maturing, and the production volumes are increasing. In parallel, expectations on performance, lifetime and operational range for fuel cell stacks are growing. As fuel cell technology matures, more fuel cell stacks are used in real life applications instead of laboratory environment. These positive developments bring with them new challenges and opportunities to learn.Several of these challenges and their impact on stack design and validation will be discussed. The focus will be on optimization of useful stack power density, fuel cell stack conditioning, enlarging the LT-PEM fuel cell operation range and on durability testing.This talk addresses why conditioning and durability testing are closely connected and illustrates how this can impact stack platform and fuel cell development. In addition, the interactions between power density, stack integration and stack operational window are illustrated showing how each of these parameters could be optimized utilizing a current distribution plate and what trade-offs are relevant for optimized fuel cell stack and system performance.Powercell is active in various market segments and has developed stacks and stack components for ~20 years. The optimizations and trade-offs described hinge heavily on key PEM stack requirements which can be widely different in different PEM fuel cell market sectors, as illustrated by the emerging usage of fuel cells in aviation.

Large-Scale DFT Calculations on Size and Site Dependences of Atomic and Electronic Structures in Metallic Nanoparticle Catalysts

Size control of Pt nanoparticle catalysts is one of the key challenges in fuel cell development. Miniaturization of Pt nanoparticles is expected to increase activity and save the amount of Pt, while very small particles (e.g. sub-nano particles or clusters) have different electronic structures and stabilities from “nano” particles. To investigate the atomic and electronic structures of materials, first-principles density functional theory (DFT) calculation is a powerful tool. However, because of its high computational cost, the DFT applications have been limited mainly for small particles and clusters of tens to hundreds of atoms. In this study, by using our own large-scale DFT calculation method, we investigate the size and site dependences of atomic and electronic structures in Pt nanoparticles with the diameters of several nanometers, which are comparable to the sizes of the particles in practical use.The computational cost of the conventional DFT calculation methods scale cubically to the system size, i.e., the number of the atoms in the target system and the number of local functions for each atom, which are used to express electronic density. We have developed the multi-site support function (MSSF) method [1,2], in which local functions are constructed as the linear combinations of the atomic orbital functions belonging to not only the target atom but also its neighboring atoms. The MSSF method enables us to reduce the number of local functions to be the minimal-basis size, leading the dramatical computational cost reduction. The MSSF method is implemented in our large-scale DFT code CONQUEST [3,4].We optimized the structures of Pt nanoparticles with the diameters of 0.5 nm (13 atoms) - 5.5 nm (3871 atoms) and found that the Pt-Pt bond lengths inside the nanoparticle converge to those in bulk Pt when the nanoparticle size becomes large. The similar trend is found also in the electronic structures as shown in the figure. In the presentation, we compare the size dependence of the stability and atomic and electronic structures of Pt nanoparticle with other metallic nanoparticles. Site dependence of the electronic structures and reactivity with molecules are also investigated by using large-scale DFT together with statistical analysis.[1] A. Nakata, D. R. Bowler, T. Miyazaki, J. Phys. Soc. Jpn., 91, 091011 (2022). [2] A. Nakata, D. R. Bowler, T. Miyazaki, Phys. Chem. Chem. Phys. 17, 31427 (2015). [3] http://www.order-n.org/ [4] A. Nakata, J. S. Baker, S. Y. Mujahed, J. T. L. Poulton, S. Arapan, J. Lin, Z. Raza, S. Yadav, L. Truflandier, T. Miyazaki, D. R. Bowler, J. Chem. Phys., 152, 164112 (2020). Figure 1

Titanium Compound Coating on SUS Separator for PEFC By Screen Printing

Currently, the metal separators of polymer electrolyte fuel cells (PEFCs) are mainly made of Ti alloys with press working. According to the report by Strategic Analysis Inc1), Ti separator accounts for a large ratio of the PEFC stack cost. To reduce this cost, it is effective to use inexpensive stainless steel and to apply the coating by screen printing, which is relatively easy to form patterns and less expensive than evaporation or sputtering. However, stainless steel has lower corrosion resistance than that of titanium, and its conductivity decreases in aqueous solution due to the formation of passive film. The purposes of this study are to develop a coating with excellent corrosion resistance and conductivity, as well as adhesion and durability, and to apply the coating on stainless steel by screen-printing. Titanium nitride and titanium carbide were employed as tillers among titanium compounds that have high corrosion resistance and sufficiently low electrical resistivity comparable to that of titanium. As a result of the research, a coating thickness of several hundred micro-m became possible, and it was decided that the gas flow path fabrication would also be done by screen printing.In this experiment, we used titanium nitride powder with different particle sizes, Olycox KC-1300 as binder, and 2-(2-butoxyethoxy) ethyl acetate as solvent to prepare printing pastes. 4 g of binder and 10 mL of solvent were weighed and stirred at 80°C for 12 hours using a magnetic stirrer. 4 g of the stirred solution was mixed with 4 g of titanium nitride powder to form a paste. The paste was screen-printed on SUS304 using a plate simulating a gas flow channel, and then dried at 250°C for 6 hours. The resistance of the coatings prepared by the above method was evaluated after pressure treatment. In addition, anodic polarization was measured in a three-electrode system. The contact resistance was targeted to be less than 10 mΩcm2 , the target value for the contact resistance of PEFC separators, as specified by the U.S. DOE.2) References 1) Mass Production Cost Estimation of Direct H2 PEM Fuel Cell Systems for Transportation Applications: 2017 Update, Brian D. James, Jennie M. Huya-Kouadio, Cassidy Houchins, Daniel A. DeSantis, Strategic Analysis Inc., December 2017.2) Fuel Cell Technologies Multi-Year Research, Development, and Demonstration Plan, U.S. DOE, 2017

Oxygen Reduction Reaction Activity of Pt on Various Carbon Supports in OH- conducting Ionic Liquids

The intermediate temperature operation above 100 °C is one of important targets of next generation fuel cell development from both points of view of the activity enhancement and carbon monoxide poisoning mitigation of catalysts. To tackle this challenge, we have synthesized and applied OH- conducting ionic liquids as new fuel cell electrolytes, in which the progress of oxygen reduction reaction (ORR) has been successfully confirmed at temperatures above 100 °C under non-humid conditions. However, there is a problem to be solved that the overpotential for ORR is high due to the strong adsorption of ionic species on Pt catalyst. In this study, the electronic state of Pt catalyst was designed by applying heterogeneous atom-doped graphene materials as catalyst supports to reduce the ORR overpotential.A 1:1 mixture of tetrabutylphosphonium hydroxide (TBPOH) and tributylmethylphosphonium bis(trifluoromethanesulfonyl)imide (P4441TFSI) was prepared and used as OH- conducting ionic liquid. As Pt catalyst supports, reduced graphene oxide (RGO) and nitrogen-doped graphene (NG) were synthesized. The deposition of Pt catalyst on these graphene materials were carried out by a conventional reduction method of platinum chloride with ethylene glycol.The ORR activity of Pt catalysts supported on various carbon materials was evaluated by cyclic voltammetry in O2 saturated TBPOH/ P4441TFSI at 120 °C, and the positive shift of ORR onset potential from 0.4 V to 0.6 V and then 0.7 V vs. RHE was observed by changing the support from commercial Ketjen Black to RGO and then NG, accompanied by an increase in the ORR current density. X-ray photoelectron spectroscopy (XPS) revealed that this improvement is related to the different electronic state of Pt catalyst, and it was suggested that the supports with higher electron donating properties such as NG are suitable for Pt catalyst to enhance the ORR activity. Figure 1

(Invited) Fuel Cell Technologies: A U.S. Department of Energy Perspective

The U.S. Department of Energy (DOE) supports activities focused on the development of fuel cell technologies that are competitive with incumbent and emerging technologies across diverse applications. Fuel cell technologies for heavy-duty transportation applications are of particular interest as significant reductions in both carbon emissions and criteria pollutant emissions can be achieved.DOE engages in fuel cell research, development, and demonstration (RD&D), working closely with its national laboratories, universities, and industry partners to overcome critical technical barriers to fuel cell development. For heavy-duty applications, RD&D is focused on the development of direct hydrogen-fueled proton-exchange membrane fuel cells (PEMFCs). PEMFC RD&D addresses the materials, component, system, manufacturing, and supply chain challenges to accelerate the commercialization of zero-emission medium- and heavy-duty vehicles, with transferable benefits for other applications.The DOE’s RD&D strategy for fuel cell technologies is driven by application-specific targets. For long-haul fuel cell trucks, these include 2030 targets for cost ($80/kW at high volume production) and durability (25,000 hours). For comparison, the cost in 2023 of a PEMFC system for long-haul trucks based on next-generation laboratory demonstrated technology is projected to be approximately $170/kW when manufactured at a volume of 50,000 units/year.DOE supports a portfolio of RD&D projects and has established the national lab-led Million Mile Fuel Cell Truck Consortium (M2FCT) to advance durability and efficiency of PEMFCs for heavy-duty vehicle applications. M2FCT’s RD&D focuses on meeting a membrane electrode assembly (MEA) target by 2025 that combines efficiency, durability, and cost in a single goal: 2.5 kW/gPGM specific power (1.07 A/cm2 current density) at 0.7 V after 25,000 hour-equivalent accelerated durability test.Supported by the U.S. Infrastructure Investment and Jobs Act, DOE pursues advances in manufacturing and recycling of clean hydrogen technologies to bridge the gap between technology development and deployment. Enabling economies of scale will require a reliable supply of components, automation of the cell and stack assembly, and manufacturing capabilities not seen in the field to date. DOE established capacity targets for heavy-duty fuel cell component and stack production, including a target of 20,000 stacks per year in a single production line by 2030 to enable market lift-off.The DOE’s RD&D portfolio includes recently selected industry-led manufacturing and component supply chain development projects. To complement these projects, DOE relaunched the national lab-led Roll-to-Roll Consortium to advance high-throughput fuel cell and electrolyzer manufacturing, with emphasis on PEM MEA and MEA components.End-of-life challenges for fuel cells and electrolyzers are also addressed. DOE is establishing a consortium of industry, academia, and national labs to develop innovative and practical approaches to enable the recovery, recycling, and reuse of clean hydrogen materials and components, with the goal of securing long-term supply chain security and environmental sustainability.

Advances in Fuel Cell Performance Using Simulation Analysis in Toshiba Energy Systems & Solutions Corporation

Toshiba’s Stationary Fuel Cell SystemToshiba Energy Systems & Solutions Corporation is developing hydrogen solution, which is a key technology to achieve carbon neutral. Now we are manufacturing the pure hydrogen fuel cell systems for stationary application. This fuel cell systems have some models up to 100kW, and in order to provide the larger electricity than 100kW, the 100kW system can be operated connecting several units up to 1MW.Toshiba's fuel cell systems have been achieved stable, long-term operation, high durability, and high energy efficiency. These features are realized by internal water management cell stack conflagration using porous carbon bi-polar plates. The porous bi-polar plates can humidify reactant gases supplied as vapor from the surface of the porous bi-polar plates and removes produced water through the porous bi-polar plates by the pressure difference between the reactant gases and the coolant water. This technology realizes ideal conditions in terms of water activity entire active area, suppressing overpotentials due to flooding and temperature and water activity distribution. This technology enables stable continuous operation up to 1 week and design life of 80,000 hours confirmed by demonstration tests, which is one of the highest in the world.Recent trends in fuel cell development include the growing expectation and demand for higher capacity and long durability fuel cell systems for stationary applications such as carbon neutral complexes and data centers, etc. In addition, demand for high power density fuel cell systems for large commercial mobility vehicles, such as buses and trucks, is also increasing. In order to meet this demand, Toshiba is developing elemental technologies for higher performance fuel cells.Development of advanced high performance fuel cellsIn order to improve cell performance, it is necessary to reduce ohmic, activation, and diffusion polarizations. Among these three overpotentials, a reduction of diffusion polarization is particularly important to achieve operation up to the high current density. To reduce diffusion polarization, the flow field of bi-polar plates must be designed to improve the limiting current density by efficient gas supply to the catalyst layer and to reduce mass transport resistance in the gas diffusion layer and catalyst layer.Toshiba has focused on reducing this diffusion polarization and is working on the flow field design using numerical simulation. As an example, Toshiba has developed the advanced numerical simulation by introducing mass transfer models of water evaporation and water absorption on the surface of a porous bi-polar plates into a commercially available electrochemical reaction and thermal fluidics 3D simulator.This porous bi-polar plates model was then used to perform parametric study of the flow field design, and determine parameters in terms of gas diffusivity, electrical resistance, and temperature and humidity distribution. And then, the advanced cell that incorporating designed bi-polar plates, thinner components, and a new catalyst was fabricated and evaluated. Figure 1 shows comparison of cell performance between conventional and advanced cells. The limiting current density of advanced cell is 3.6 times larger than that of conventional cell due to simulation-based flow field design and optimization of operating pressure. The application of these development items and optimization of operating conditions reduced each polarization and achieved a current density twice that of conventional cell. In the future, we aim to achieve even higher performance by improving catalytic activity and reducing cell resistance through thinner components. Figure 1

PH Dependence of Dihydroxyacetone Oxidation by Electrocatalytic Viologen Self-Assembled Monolayers on Gold Electrodes.

Carbohydrate fuel cells garner much research interest as the world's focus shifts from fossil fuels to renewable energy. Many catalyst options are available for carbohydrate fuel cell development, including enzymes and microbes, various metal-based catalysts, and natural or synthetic mediators. Research challenges include low power output, system fouling and poisoning, inefficient electron release, and complex mechanisms, with multiple pathways leading to low product selectivity. Here, we further investigate a novel approach to catalyze carbohydrate oxidation using Au electrodes with viologen self-assembled monolayers (SAMs). SAM-mediated fuel cells have the potential to address the challenges of other catalyst systems by protecting the electrode surface and controlling the local concentration and structure to increase current generation. The effects of increasing pH on dihydroxyacetone (DHA) oxidation by three viologen SAMs on Au electrodes are presented. Current and power generated during DHA oxidation at varying pH were measured and compared to those of bare Au performance. Two of the SAMs produced more current and power than bare Au at elevated pH. The SAM system produced more current and peak power per molecule than both dilute and concentrated homogeneous viologen systems in the same cell setup. These results demonstrate the benefits and limitations of electrodes modified with redox-active groups for the production of electricity from simple sugars and other carbohydrate sources. These results are encouraging for the development of new strategies for electrical power generation from renewable resources.

Preparation and performance study of solid electrolyte Ce0.80Gd0.04Sm0.04Er0.04Y0.04RE0.04O2-δ (RE= Yb, Dy, Eu, Nd, Pr, La)

The production of highly conductive electrolytes has been a crucial factor in the practical development of Solid Oxide Fuel Cells (SOFCs). This study highlights the impact of different dopants on the crystal structure, microstructure, and ionic conductivity of a ceria-based matrix within the Ce0.80Gd0.04Sm0.04Er0.04Y0.04RE0.04O2-δ system. The Ce0.80Gd0.04Sm0.04Er0.04Y0.04RE0.04O2-δ (RE = Yb, Dy, Eu, Nd, Pr, La) powders were prepared using the solid-state reaction method. The phase structure, microstructure, and ionic conductivity of the GSEYRE series electrolytes were analyzed using XRD, SEM, EDS, TEM, XPS, AC impedance spectroscopy, and thermal expansion analysis. Phase structure analysis confirmed that all multi-doped electrolytes possessed a cubic fluorite structure with the Fm3m space group. After sintering at 1400 °C for 10 h, all samples exhibited densities exceeding 94 %. XPS analysis revealed a high concentration of oxygen vacancies in the GSEYRE. Electrical performance analysis showed that the Ce0.80Gd0.04Sm0.04Er0.04Y0.04Dy0.04O2-δ (GSEYD) electrolyte demonstrated the highest ionic conductivity (σt = 3.36 × 10−2 S/cm) and the lowest activation energy (Ea = 0.78 eV) at 800 °C. The thermal expansion coefficient of the developed electrolytes matched well with commonly used electrode materials. These characteristics make GSEYD a promising candidate for use as an electrolyte material in SOFCs.

The Effect of Saccharin on SnNi Alloy: the Electrodeposition and its Electrocatalytic Activity in Ethanol Oxidation Reaction

The development of Direct Ethanol Fuel Cell (DEFC) has attracted much attention, as alternative energy sources due to its various advantages. However, among its various advantages, DEFC has several problems, such as the kinetics of the ethanol oxidation reaction. Transition metal-based catalysts such as nickel and tin are considered as potential catalysts for DEFC due to their oxophilic properties that can improve catalytic activity. In this study, the effect of saccharin on SnNi bimetallic alloy catalyst synthesized by electrodeposition method on copper wire substrate was investigated. SnNi samples were characterized by several techniques, including X-ray diffraction, Scanning electron microscopy, and energi dispersive X-ray spectrocopy. Saccharin addition had a significant effect on the morphology, crystallite size, and composition of the catalyst. The presence of saccharin causes the formation of more uniform particles and has a smaller size. The sample with the addition of saccharin had a smaller charge transfer resistance value 4.82 Ω, lower tafel slope by 115 mV/dec, and show higher jf/jb ratio by 0.55. Furthermore, as the current density decreases, the SnNi catalyst with saccharin has a slow decrease rate and higher stability than the SnNi catalyst without saccharin.

Outstanding Activity and Durability of Supported NiCo2O4 Nanoparticles for Direct Ethanol Fuel Cells

ABSTRACTThe rational design of noble metal‐free electrocatalysts represents one of the basic stones for fuel cell development. With the exploration of eco‐friendly nanomaterials for the investigated alcohol oxidation process, nickel‐based electrodes have been recognized as the most auspicious anodes with promoted activity and stability. In this work, a series of NiCo2O4 nanoparticles were deposited onto graphite sheets (NiCo2O4/T) introducing varied proportions of cobalt oxide species. Co‐precipitation protocol of the respective metallic hydroxides onto the carbonaceous support was followed with consecutive annealing in an air atmosphere at 400°C. The fabricated mixed metallic oxide nanopowder was physically studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X‐ray analysis (EDX), X‐ray photoelectron spectroscopy (XPS), and selected area electron diffraction (SAED). Uniformly arranged nanoparticles were observed on graphite surface as evidenced by SEM and TEM. The cubic lattice structure of formed NiCo2O4 crystals was also confirmed by XRD through the defined peaks of binary metallic oxides clarifying their successful preparation scheme. The electrocatalytic properties of these NiCo2O4/T nanocatalysts were evaluated for oxidizing ethanol molecules in basic solution. Pronounced oxidation current densities were remarkably measured at NiCo2O4/T electrodes in relation to that at NiO/T. Differing the introduced cobalt oxide content into the synthesized nanocatalyst significantly controlled its catalytic performance. NiCo2O4/T‐20 exhibited the highest activity and stability among the prepared nanomaterials. Much decreased charge transfer resistances were also recorded at this electrode demonstrating its promoted electron transfer characteristics. This work could provide a reasonable route for the simple synthesis of comparable transition metallic oxides with promising attitudes for energy generation purposes.

Study of the Sodium Borohydride Hydrolysis Reaction's Performance via a Kaolin-Supported Co-Cr Bimetallic Catalyst

Hydrogen is an attractive source of energy because of its properties, which include superior quality, effectiveness, pureness, dependability, and sustainability. Technologies for producing and storing hydrogen are being developed in parallel with fuel cell development. Chemical storage of hydrogen in a metal hydride containing boron eliminates the problem of hydrogen transportation and storage. Through catalytic reactions, hydrogen stored in solid form in boron hydrides can be recovered. In this study, a nowel developed Co-Cr bimetallic catalyst supported by kaolin, a natural mineral, was synthesized to be used for hydrogen production by hydrolysis of sodium boron hydride. The structural characteristics of the produced Co-Cr@Kaolin catalyst were ascertained by EDX, FTIR, and SEM analyses. Next, the ideal conditions for the hydrolysis reaction of sodium borohydride (NaBH4) catalyzed by Co-Cr@Kaolin were examined. These included the concentration of the catalyst, the amount of support material (kaolin), the amount of catalyst, and the concentration of NaBH4. The optimal hydrolysis conditions were found to be 2.5% NaOH concentration, 40 mg of catalyst, and 2% NaBH4 concentration at 303 K. The maximum rate of hydrogen production was determined as 5007 ml g-1 min-1 under optimal conditions. After conducting hydrolysis operations at different temperatures to elucidate the reaction kinetics, it was found that the catalytic hydrolysis reaction was of the 0th order and that the reaction activation energy was 19.36 kJ mol-1. The hydrogen production rate obtained as a result of the hydrolysis reaction accompanied by a Co-Cr catalyst was determined as 3166 ml g-1 min-1. It is therefore established that supporting kaolin to Co-Cr catalyst enhances its efficacy.

Development and experimental investigation of a new direct urea fuel cell

This study concerns the development and experimental investigation of Direct Urea-Hydrogen Peroxide Fuel Cells (DUHPFC), with a particular emphasis on electrode preparation using nickel zinc iron oxide coated on stainless steel foil via the electrochemical deposition method, and the performance evaluation of single cells under varying operational conditions is also performed. This electrochemical deposition helps achieve a uniform and stable anode coating, which exhibits the high catalytic activity and stability, resulted in significantly enhanced urea oxidation reaction. The research further identifies an optimal performance for a single cell at 25 °C with 9 M KOH and 0.5 M urea, achieving a peak power density of 46.38 mW/cm2. The single cell demonstrates an open circuit voltage (OCV) of 0.72 V. Both energy and exergy efficiencies are further investigated for the cell performance and found to be 58% and 24%, respectively, at 5 M KOH. The electrochemical impedance spectroscopy (EIS) results reveal a significant reduction in impedance, from 30-Ωcm2 at 25 °C to 15-Ωcm2 at 65 °C, indicating an enhanced ionic conductivity and a reduced resistance. The present study results suggest that optimizing the electrode composition and operational parameters significantly improves the DUHPFC's performance, offering valuable insights for future fuel cell development.

Superprotonic Conductivity by Synergistic Blending of Coordination Polymers with Organic Polymers: Fabrication of Durable and Flexible Proton Exchange Membranes.

Creation of an efficient and cost-effective proton exchange membrane (PEM) has emerged as a propitious solution to address the challenges of renewable energy development. Coordination polymers (CPs) have garnered significant interest due to their multifunctional applications and moldability, along with long-range order. To leverage the potential of CPs in fuel cells, it is essential to integrate microcrystalline CPs into organic polymers to prepare membranes and avoid grain boundary issues. In this study, we designed and synthesized CPs containing imidazole and sulfonate moieties via gel-to-crystal transformation. The integration of CPs into the PVDF-PVP matrix resulted in superprotonic conductivity in the order of 10-2 S cm-1 at room temperature (30 °C) and 98 % RH. The proton conductivity achieved with CP-integrated composite membrane was 4.69×10-2 S cm-1 at 80 °C and 98 % RH, the highest among all CP/MOF-integrated PVDF-PVP membranes under hydrous conditions. The excellent compatibility of CPs with PVDF-PVP produced highly flexible membranes with superior mechanical, chemical, and thermal stability. About 25 times higher proton conductivity value was achieved with membrane, compared to intrinsic CPs, at RT and 98 % RH. Thus, we present a cost-effective CP-integrated mixed-matrix membrane with superprotonic conductivity and long-term durability for cutting-edge fuel cell development.

Combining physical modeling and machine learning for micro-scale modeling of a fuel cell electrode

Abstract Microscale modeling plays a critical role in fuel cell development, offering deep insights into the microscale transport phenomena and electrochemical reactions. This level of detail is essential for optimizing the performance of a single fuel cell, enabling the precise design and improvement of materials and structures at the microscale and consequently enhancing the overall efficiency of a stack. Here, we show a comprehensive transition from white-box models, characterized by their reliance on physical laws, to black-box models exemplified by neural networks, which excel in pattern recognition from provided data without necessitating a clear understanding of the underlying processes. This spectrum encompasses the inherent challenges and merits of both methodologies. While white-box models are recognized for their reliability due to their foundation in mathematical equations that describe physical phenomena, they often require the integration of empirical parameters and are susceptible to experimental errors, much like their black-box counterparts. The core novelty in this study lies in the synergistic integration of these two paradigms, specifically tailored for enhancing the predictive accuracy in solid oxide fuel cell modeling. In this approach, the neural network is employed to replace different parts of the mathematical model, from refining empirical parameters in the electrochemical model to replacing the entire electrochemical model. The adjustment of parameters is conducted by an evolutionary strategy based on the outputs of the mathematical model. The results underscore the superiority of the gray box in achieving higher prediction accuracy and in minimizing the requisite data volume for network training. This presented approach not only bridges the gap between the deterministic clarity of white-box models and the data-driven insights of black-box models but also strategically distributes the computational load between them, thereby offering a promising solution to the prevalent challenges in solid oxide fuel cell modeling.

Investigating the properties of nanoparticles from heveabrasiliensis shell for coolant application in PEMFCs

Extensive consumption of petroleum-based products, which has resulted in energy depletion, prompted a need to seek alternative and renewable means of transportation. PEMFCs can achieve high power density, low operating temperatures, rapid start-up, and clean energy, making them ideal for transportation. Several studies have demonstrated that conventional cooling agents, such as water or water with ethylene glycol, do not dissipate heat efficiently in PEMFCs, resulting in deteriorating performance and a shortened operational lifespan over time. The incorporation of bio-sourced nanofluids as an alternative coolant for Proton Exchange Membrane (PEM) fuel cells is the newest venture to take over PEM fuel cell development. Utilizing bio-sourced nanofluids is being evaluated for elevating the heat conduction and decreasing the electrical conductivity of proton exchange membrane fuel cells (PEMFCs). The objective of this article is to investigate Hevea brasiliensis Shell (HBS)-based nanofluids dispersed in water and Ethylene glycol (EG) at varying concentrations of 0.1 vol%, 0.3 vol%, and 0.5 vol% by paying attention to improving heat transfer, extracting high electrical output, reducing pump loss, and increasing the longevity of cells. As an adverse effect, incorporating HBS at a 0.5 % volume concentration within an 80:20 mixture of water and ethylene glycol (W:EG) resulted in an 8 % improvement in heat transfer and a 77 % increase in electrical conductivity when compared to W:EG (80:20), which is promising as a pertinent cooling technique for PEMFC stacks.

Development and Application of Low Temperature Solid Oxide Fuel Cell

Development and Application of Low Temperature Solid Oxide Fuel Cell

Enhanced oxygen reduction reaction on caffeine-modified platinum single-crystal electrodes

Enhancing the activity of the oxygen reduction reaction (ORR) is crucial for fuel cell development, and hydrophobic species are known to increase the ORR activity. This paper reports that caffeine enhanced the specific ORR activity of Pt(111) 11-fold compared to that without caffeine in a 0.1 M HClO4 aqueous solution. Moreover, caffeine increased the ORR activity of Pt(110) 2.5-fold; however, the activity of Pt(100) was unaffected. The infrared (IR) band of PtOH (blocking species of the ORR) decreased for all the surfaces. Caffeine was adsorbed with its molecular plane perpendicular to the Pt(111) and Pt(110) surfaces and tilted relative to the Pt(100) surface. Thus, the effects of caffeine on the ORR activity can be rationalized by a decrease in PtOH coverage and the difference in adsorption geometry of caffeine.

Auxiliary-ejector-based hydrogen recirculation system to broaden PEMFC operating range

This study presents an auxiliary-ejector-based hydrogen recirculation system to widen the operating range of the proton exchange membrane fuel cell system (PEMFCS). An auxiliary ejector (BE) design model is presented and then an experimentally verified two-dimensional numerical-simulation model is built to study the relationships between PEMFC output power, ejector geometrical parameters, and its performance (μ) based on sensitivity analysis. Finally, the operating characteristics of the BE are clarified. The results show that the μ is highly sensitive to position (Lb), followed by width (w) and angle (A) of auxiliary port. The BE can provide satisfactory μ above 0.8 under higher power output, and a μ higher than 0.6 for lower power output with the Lb, A, and w of 1.1, 30°, and 4 mm when PEMFCS works from 17.9 to 84 kW. This proposed system can extend the operation range of PEMFCS using a single ejector, which can contribute to fuel cell development.

Development of a High-Performance Ammonium Formate Fuel Cell

Direct liquid fuel cells fueled by molecules such as methanol, ethanol and formate have received many attentions as proton exchange membrane fuel cells, primarily because of its high energy density, simple structure, small fuel cartridge, and ease storage and transport of fuels. Among them, formate, mainly referring to sodium formate or potassium formate, has drawn increasing interest due to the following advantageous characteristics: a high theoretical voltage of 1.45 V, facile and complete formate oxidation in alkaline media, and easy handle in storage and transportation. However, the cation ion (Na+ or K+) in the fuel solution does not contribute to electricity generation but only increase the extra weight load of the fuel cell system, thus lowering the energy density of formate to 2.1 kWh L-1. In this work, ammonium formate is adopted as the fuel, which not only retains the advantages of formate, but also substitutes the Na+/K+ with ammonium (NH4 +) that can be simultaneously oxidized to release electrons, i.e., electricity generation. Hence, the energy density ammonium formate is upgraded to 3.2 kWh L-1. Although promising, the development of ammonium formate fuel cell has been hindered by technical challenges related to the oxidation of ammonium formate, such as sluggish kinetics and electrode degradation. To tackle these issues, a bimetallic Pt-Pd/C electrocatalyst is synthesized by a facial chemical reduction method using sodium borohydride as agent. The Pt-Pd/C electrocatalyst exhibits better electrocatalytic activity for ammonium formate oxidation than pure Pt/C and Pd/C. Then, an ammonium formate fuel cell is developed and tested, which is composed of a Pt-Pd/C anode, a single-atom Fe/C cathode, and an anion exchange membrane (Figure 1). This fuel cell yields an open-circuit voltage (OCV) of 0.88 V and a peak power density (PPD) of 60.7 mW cm-2 at 60oC. When the hydrogen peroxide is used as oxidant, the OCV and PPD are boosted to 1.31 V and 99.6 mW cm-2, respectively. Further increasing the operating temperature to 90oC leads to a PPD of as high as 187.6 mW cm-2. In addition, a mathematical model incorporating mass/charge transport and electrochemical reactions is developed to shed light on the voltage losses and provide guidance for optimizing structural design and operating parameters.AcknowledgementThis work was supported by a grant the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. N_PolyU559/21) and The Hong Kong Polytechnic University Centrally Funded Postdoctoral Fellowship Scheme (Project No. 1-YXAZ).Figure 1 Schematic of an ammonium formate fuel cell. Figure 1

Novel Designs for 7-Layer Membrane Electrode Assembly in PEM Fuel Cells: A Systematic Investigation of Mass Transport and Charge Transfer Processes in PEM Fuel Cells

During the last decades, the focus of PEM fuel cell development in automobile applications has been mostly dedicated to the optimization of the catalyst-coated membrane (CCM). Nevertheless, the optimum design of other components like the gas diffusion layer, or gas flow fields can directly influence the overall performance of the PEM fuel cell. The gas diffusion layer (GDL) itself plays a crucial role in the water balance in a PEM fuel cell. Besides, an optimized combination of GDLs and gas flow fields leads to the efficient distribution of reactants on catalyst layers. Our main goal for the development of the 7-layer membrane electrode assembly in PEM fuel cells is to reduce the corresponding thickness. This will both improve the efficiency of mass, electrical, and heat transport processes and reduce materials and energy consumption during production. Thus, it will contribute in two ways to support the commercialization of PEM fuel cells.Further intentions of our new GDL designs are, on one hand, optimizing the capillary pressure gradient for a smooth discharge of saturated water between the catalyst layer and gas flow fields. On the other hand, enhancing the gas transport to the catalysts layer by reducing diffusion length. These could be obtained by innovative engineering of microporous structures in GDLs. Thus, following beyond the previous investigation of our research group to enhance the capillary pressure gradient, and subsequently, mass transport, in this study the design of the microporous layer is purposely varied by applying different mono disperse polymer particles as pore former. In addition, to reduce the cell width in a disruptive manner, two innovative architectures have been investigated. The first one consists in eliminating the gas diffusion medium (GDM) and thus keeping only the newly-designed MPLs. Consequently, in comparison with a conventional GDL, the uncompressed material thickness is reduced from approximately 200 µm to around 40 µm. The second cell architecture is based on the integration of the refined gas flow fields directly at the back of the GDL which enables us to get rid of “large” rib/channel designs used in state-of-art bipolar plates.In this contribution, the effect of new-designed MPLs, as well as the mechanically machined GDL on both mass transport and the charge transfer processes have been evaluated and significant performance gains have been obtained. Additionally, the scale-up possibility from the single-cell design to short-stack PEM fuel cells will be discussed.This work from the “DOLPHIN” project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under Grant Agreement No 826204. This Joint Undertaking receives support from the European Union’s Horizon 2020 Research and Innovation program, Hydrogen Europe and Hydrogen Europe Research.