bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the Effect of Ammonia As Ambient Air Contaminant on PEM Fuel Cell Stack Performance and Degradation Using EIS, Thda and Different Gas Analysis Methods
Authors: Özel Tansu , Bürger Stefan , Cremers Carsten 
Published: December 2024

The negative effects of airborne contaminants on polymer electrolyte membrane fuel cell (PEMFC) have already been shown in several publications. [1] Among these contaminants, ammonia (NH3) with its multistep reversible and irreversible effects is particularly significant. Recent studies on air quality in urban areas have revealed a notable increase in ammonia levels within a span of two years. [2] This rapid increase can be attributed to the growing prevalence of EURO-6 diesel vehicles equipped with selective catalytic reduction (SCR) cats, which results in ammonia slip during the nitrogen oxide reduction process in diesel engines. [2]
Ambient air is the most common used oxidant gas in mobile and stationary PEM fuel cell systems. The performance of fuel cell can suffer beyond the oxygen gain from airborne contaminants, which also have the potential to accelerate degradation. To prevent that airborne contaminants reach the fuel cell cathode, air filter systems consisting of particle filter and specially for fuel cell requirements developed filter are installed at the cathode inlet. Despite the installation of an air filter system, airborne contaminants can still reach the fuel cell cathode.
The focus of this investigation is on the effects of ammonia in PEM fuel cell stacks. In contrast to single cell operation, stack operation can introduce additional effects such as cell-to-cell inhomogeneities and varying degrees of ammonia-induced degradation among cells. For the investigation, experiments with a PEMFC stack are going to be done on a fuel cell testbed equipped with an impedance analyzer. Ammonia is going to be mixed into the cathode air in the ppb range. Its effects on PEMFC stack performance are going to be investigated with electrochemical impedance spectroscopy (EIS) and total harmonic distortion analysis (THDA). The cathode exhaust gas is also going to be analyzed by gas analyzers such as FTIR gas analyzer and mass spectrometry.
It is planned to test the PEMFC stack under different operating conditions like temperature, relative humidity and pressure of inlet gases, with various parameters and different cathode gas mix ratios while monitoring possible conversion of impurities via FTIR and the stack state of health using THDA and conventional technologies to understand the link between the effect of ammonia on fuel cell stack performance, on its lifetime and to determine possible early indicators.
References
[1] Misz, U., Talke, A., Heinzel, A., and Konrad, G. 2016. Sensitivity Analyses on the Impact of Air Contaminants on Automotive Fuel Cells. Fuel Cells 16, 4, 444–462.
[2] R. Wegener, U. Javed, R. Dubus, and D. Klemp. 2024. Investigations of Air Quality Aspects with the Urban Climate Model PALM4U.
(Invited) Structure/Transport Relations in Electrolytes: What Have We Learned from Modeling in the Past Quarter Century?
Authors: Paddison Stephen J. 
Published: December 2024

The development of highly efficient energy conversion devices that utilize sustainable fuel sources with components that are thermally stable, chemically robust, and economically and environmentally feasible and sensible is an important research trust. The electrolyte in low temperature fuel cells is typically an ion containing polymer: either a proton exchange membrane (PEM) or an anion exchange membrane (AEM). Of the many properties that are critical to the effective function of a membrane as the electrolyte and separator in a fuel cell none is more important than the ionic conductivity. The hydrated morphology of either a PEM or an AEM determines many aspects that govern the transport of species (i.e., H2O, H+(H2O), and/or OH-(H2O)). Transport mechanisms in these soft materials are complex as they involve interactions of the cations and anions, the mobile and tethered ions with the water, and the relaxation dynamics of the polymeric backbones and side chains.
Over the past 30 years, numerous theoretical and computational studies have been undertaken with a focus at understanding ion and water transport in PEMs and AEMS. This talk will attempt to review what has been learned over the past 25 years from modeling and simulation on the connections, correlations, and relations of polymer structure and architecture to transport properties.
(Invited) Investigation of Co-Free Cathode Composited with Proton Conductors for Protonic Ceramic Fuel Cells with Yb-Doped BaZrO3 Electrolyte
Authors: Watanabe Konosuke , Shimada Hiroyuki , Sharma Aman , Fujioka Masaya , Yamaguchi Yuki , Nomura Katsuhiro , Sumi Hirofumi , Mizutani Yasunobu 
Published: December 2024

Protonic ceramic fuel cells (PCFCs) are expected to gain significant advantage from the use of Co-free cathodes. This shift can lead to reduced manufacturing costs and enhance durability performance. In our previous study, the investigation compared the power generation characteristics of PCFCs with BaZr0.8Yb0.2O3-δ
(BZYb) electrolytes utilizing cathodes composed of La0.6Sr0.4FeO3-δ
(LSF) as a Co-free cathode material and La0.6Sr0.4CoO3-δ
(LSC) or La0.6Sr0.4Co0.2Fe0.8O3-δ
(LSCF) as Co-containing cathode materials composited with BZYb. Consequently, the PCFC with an LSF-BZYb cathode exhibited lower performance compared to the PCFCs with LSC-BZYb and LSCF-BZYb cathodes due to the higher electrode polarization resistance.
In this study, the challenges associated with achieving high-performance Co-free cathodes that can match the performance of Co-containing cathodes are presented, along with the mechanism to enhance performance. To improve performance, the use of La0.65Ca0.35FeO3-δ
(LCaF), as a Co-free cathode, in addition to LSF, which has been reported to demonstrate high performance in SOFCs, was explored. Additionally, LCaF was composited with BaCe0.7Zr0.1Y0.1Yb0.1O3-δ
(BCZYYb), known for its higher proton conductivity and easier sinterability than BZYb.
When comparing the power generation characteristics of PCFCs with LCaF-BZYb and LSF-BZYb cathodes, the PCFC with LCaF-BZYb cathode exhibited higher ohmic and electrode polarization resistances. These results were attributed to weak adhesion between the electrolyte and cathode, resulting in lower performance than the PCFC with LSF-BZYb cathode.
Furthermore, when comparing the power generation characteristic of the PCFC with a composite cathode of LCaF and BCZYYb with the LCaF-BZYb cathode, the ohmic and electrode polarization resistances were significantly lower. This improvement was attributed to the advanced sintering of BCZYYb and the connected percolation of the proton-conducting network. Consequently, the performance of the PCFC with the LCaF-BCZYYb cathode surpassed that of the LCaF-BZYb cathode and was comparable to Co-containing cathodes such as LSC-BCZYYb cathode.
In conclusion, for Co-free cathodes in PCFCs, it is crucial to composite them with proton conductors possessing better sinterability, such as BCZYYb, to achieve higher performance.
Acknowledgements: This work is based on the results obtained from a project (JPNP20003) commissioned by the New Energy and Industrial Technology Development Organization (NEDO), Japan.
(Invited) Impact of Sr-Containing Secondary Phases on Oxide Conductivity in Solid-Oxide Electrolyzer Cells
Authors: Rowberg Andrew , Slomski Heather S , Kim Namhoon , Strange Nicholas A. , Gorman Brian , Shulda Sarah , Ginley David , Kweon Kyoung E. , Wood Brandon C. 
Published: December 2024

Solid oxide electrolyzer cells (SOECs) are among the most promising devices for producing hydrogen from the electrolysis of water, as they can be operated using excess heat. However, due to their high operating temperatures, they can suffer from materials degradation phenomena, including the segregation of cation species across the cells. Notably, in SOECs based on yttria-stabilized zirconia (YSZ) as the oxide-conducting electrolyte, strontium segregation from the air electrode through the barrier layer toward the electrolyte can lead to the formation of certain unwanted secondary phases, including SrO and SrZrO3.
Here, use density-functional theory (DFT) calculations based on a hybrid functional in conjunction with energy dispersive x-ray spectroscopy (EDS) to characterize these Sr-containing secondary phases and to quantify their impact on oxide conductivity in SOECs. Using our DFT calculations, we calculate the mobility and concentration of oxygen vacancies in each material, which we combine to estimate their oxide ion conductivity. We find that SrO has a low oxide ionic conductivity that will dramatically reduce SOEC performance if it is present in thick, continuous layers. Similarly, we find that SrZrO3 does not have a high conductivity due to low intrinsic vacancy concentrations; however, doping SrZrO3 with yttrium will raise oxygen vacancy concentrations and thereby oxide conductivity, even to the point of parity with YSZ. Yttrium-doping of SrZrO3 is likely, considering that it is present in YSZ alongside zirconium, which reacts with strontium to produce SrZrO3.
Our EDS analysis of post-operando SOECs confirms that Y is present as a majority impurity in SrZrO3 precipitates, while other dopants, which we find will generally reduce oxide conductivity, have significantly lower concentrations. Furthermore, EDS does not reveal large concentrations of SrO, implying that it will not form in sufficiently thick layers to block oxide conductivity, at least until the duration of testing considered here.
Our work provides a comprehensive analysis into the role that Sr-containing secondary phases play in YSZ-based SOECs, along with insights that can be used to engineer better performing and more resilient devices.
Part of this work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Part of this work was performed by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308.
Accelerating Development of Submicron-Thick Initiated Chemical Vapor Deposition (iCVD)-Derived Polymer Electrolytes for All Solid-State Batteries Via Pre-Screening Bulk Surrogates
Authors: Ford Hunter O. , Nuwayhid Ramsay , Chaloux Brian , Swift Michael W , Jayakody Nishani , Klug Christopher , Kim Youngchan , Liu Xiao , Jugdersuren Battogtokh , Long Jeffrey W. , Rolison Debra R. , Sassin Megan B. 
Published: December 2024

Initiated chemical vapor deposition (iCVD) is an emerging method for generating submicron-thick, conformal polymer coatings on structurally complex substrates, including those of interest to all solid-state 3D batteries, fuel cells, and capacitive deionization devices. From the perspective of the energy-storage community, the utility of iCVD arises from the ability to create conformal polymer anion- or cation-conducting solid-state electrolytes, artificial solid-electrolyte interphase (SEI) layers, and surface property-modifying coatings. Expanding the library of polymer chemistries and structures beyond those obtained using standard vinyl-containing iCVD monomers is essential to address the challenges facing next-generation, advanced energy storage (e.g., cycle life, suppression of unwanted ion transport). However, opening up this synthetic property-performance space for iCVD-generated materials challenges the throughput of iCVD and greatly increases the number of characterization experiments. To circumvent this challenge, we previously reported that bulk poly(dimethylaminomethylstyrene), pDMAMS, synthesized using bulk solution polymerization serves as a surrogate for iCVD-derived pDMAMS.1,2 We now extend the viability of bulk polymer surrogates to other polymer chemistries as a pre-screening option to accelerate the design and evaluation of iCVD-derived solid-state polymer electrolytes. For a selected test case involving single-anion conducting alkaline polymer electrolytes, we demonstrate how trends observed in polymer design regarding ion/mass transport and morphology on traditional bulk-synthesized polymers translate to iCVD-prepared analogs of the same systems. For example, we show that for a co-polymer system comprising divinylbenzene (DVB) and quaternized dimethylaminomethylstyrene (p[DVB-DMAMS+], increasing the crosslinking DVB content decreases ionic conductivity and restricts dynamic freedom. Using this understanding, we formulate an appropriate pre-optimized iCVD-derived p[DVB-DMAMS+] electrolyte and verify that its performance trend aligns with that of the bulk copolymer.
1. Ford, Hunter O., et al. Non-line-of-sight synthesis and characterization of a conformal submicron-thick cationic polymer deposited on 2D and 3D substrates. RSC Applied Interfaces (2024); doi: 1039/d3lf00256j.
2. Ford, Hunter O., et al. Submicron-thick single anion-conducting polymer electrolytes. RSC Applied Interfaces (2024); doi: 10.1039/d3lf00257h.
Low-Temperature Seawater Electrolysis for the Removal of Organic Contaminants and Simultaneous Hydrogen (H2) Generation
Authors: Lopez-Ruiz Juan A. , Boruah Bhanupriya , Strange Lyndi E. , Royer Nathanael , Riedel Nickolas W , Talukdar Biva 
Published: December 2024

Water (H2O) electrolysis represents a sustainable approach to produce green hydrogen (H2); however, the high energy cost (2H2O → 4H2+ O2, ∆H° = 286 kJ/mol H2, E° = −1.23 V) associated with water electrolysis and electricity cost (>$50/MWh) results in a minimum H2 selling price ≈$4/kg H2. Therefore, we need to find an alternative process to generate H2 to meet the current U.S. Department of Energy's (DOE's) Energy Earthshots of $1/kg H2 in one decade.
Seawater represents an earth abundant natural H2O source for H2 generation in island and coastal communities. However, there are several technical challenges hindering its widespread implementation such as the corrosive nature of seawater and the production of poisonous chlorine gas (Cl2) via the chlorine evolution reaction (CER: 4Cl- → Cl2 + 4e-, E° = 1.36 V vs. RHE). The CER competes against the oxygen evolution reaction (OER: 2H2O → 4H+ + 4e- + O2, E° = 1.23 V vs. RHE), thus inhibiting the production of e- and H+ needed for the H2 production via the hydrogen evolution reaction (HER: 4H+ + 4e- → 2H2, E° = 0.0 V vs RHE). Instead, we propose to use the full electrocatalytic oxidation (FECO) of naturally-occurring and artificially-made organic molecules to generate H2 (e.g., CH3COOH + 2H2O → 2CO2 + 8e- + 8H+, E° = −0.02 V vs RHE) which occurs at >1 V lower potential than CER and OER. As opposed to traditional H2O electrolysis that requires clean water streams, the proposed electrolysis technology can use readily available H2O streams containing organic molecules (e.g., municipal wastewater) combined with seawater to generate H2 while removing the undesirable organic contaminants.
In this work, we compare the performance of heterogeneous electrocatalysts for the FECO of organic molecules present in wastewater in a model seawater electrolyte (0.1−0.6 M NaCl) at room temperature. PECO electrocatalysts were developed and tested using real wastewaters derived from several sources including the hydrothermal liquefaction (HTL) of food waste. We synthesized the PECO electrocatalysts using both platinum-group metals (PGM) as well as base-group metals (BGM) and tested them as a function of half-cell potential. Our results show that both PGM- and BGM-based bimetallics improve the activity and stability compared to the baseline RuO2-based catalysts.

Figure 1
Theory Guided Discovery of Superior Ru-Based Electrocatalyst for Durable Acidic Oxygen Evolution Reaction
Authors: Zhou Li Qin , Wang Siwen , Ling Chen 
Published: December 2024

Water electrolysis (WE) using hydrogen evolution reaction is widely recognized as a promising method for clean and sustainable hydrogen production. The currently dominant alkaline-based water electrolysis encounters several challenges including high ohmic resistance, limited current density, low efficiency, and poor long-term stability. Proton exchange membrane (PEM) electrolysis can tackle these challenges by providing efficient proton transfer. However, sluggish oxygen evolution reaction (OER) in acid has been a major long-existing obstacle in PEM systems and, therefore, has attracted great research interest.
Due to its high activity and durability, IrO2 is currently considered the only practical OER electrocatalyst in PEM devices. However, Ir’s high cost and low global reserve limit its large-scale applications. Hence, less-expensive catalysts for acidic OER are in great demand. RuO2 has been recognized as an attractive alternative to IrO2 because Ru is ~100x abundant and costs ~10x less. Although RuO2 presents higher activity than IrO2, it deteriorates severely in a few hours due to its dissolution under oxidizing conditions. Its long-term stability remains a big challenge.
To overcome the challenge of improving the stability of Ru-based oxides, in this work we provide a rigid theoretical framework of RuO2 dissolution under the influence of other metal species. We show that the stability of Ru-based oxides could be controlled by varying the properties of incorporated metal oxides as well as the synergy to form a complex oxide. Surveying the Materials Project database led to the rationalization of a series of metal elements that could positively improve the stability of RuO2. Guided by our theoretical approach, we conducted high-throughput screening and experimental evaluation of Ru-based oxides for acid OER.
Our study discovered a novel Ru-based oxide with superior performance in acid OER application. A new wet-impregnation method was developed to synthesize the desired phase. The as-obtained product were uniform nanoparticles with diameters less than 5 nm in a single rutile structure. The new catalyst showed significantly better performance than pristine RuO2. In the rotating-disk-electrode experiment, our catalyst delivered a current density of 10 mA·cm-2 at an overpotential of less than 170 mV in 0.1 M HClO4. The catalyst exhibited a low degradation rate smaller than 25 μVh-1 for over 200 hours of operation at 10 mA·cm-2. Our results show great promise of Ru-based oxides as Ir-free electrocatalysts for acidic OER in PEM water electrolysis.
Performance Recovery in Irreversibly Degraded Polymer Electrolyte Membrane Fuel Cell for Enhanced Water Management
Authors: Kim Ji Yeon , Mortazavi Mehdi , Jung Sung Yong 
Published: December 2024

Polymer electrolyte membrane fuel cells (PEMFCs) offer numerous advantages, such as low operating temperatures, ease of start-up and shutdown, and high power density. Recent researches have focused on enhancing their performance for various industrial applications, particularly in transportation fields including vehicles and drones. The gas diffusion layer (GDL) in PEMFC plays a key role in the transport of fuel, oxygen, and water. The physical and chemical degradation of GDL adversely affects the water management resulting in performance deterioration.
A major cause of GDL degradation in PEMFCs is the generation of hydrogen peroxide (H₂O₂) during the electrochemical reaction. H₂O₂ lead PTFE loss and carbon corrosion, and this degradation is irreversible. Although several studies demonstrate techniques for recovering performance for the reversible degradation, limited research exists on restoring performance in irreversibly degraded PEMFCs.
This study proposes a novel approach for the performance recovery in irreversibly degraded PEMFCs by superimposing acoustic pressure waves on the oxygen gas flow which enhances the water management ability [1]. To investigate the effect of proposed recovery technique, performances were compared with or without the superimposed acoustic pressure waves using a unit cell having 25 cm² active area. The 19 % decrease in performance with aged GDL was observed due to the reduction in the water management capability caused by the decrease of hydrophobicity.
The superimposed acoustic pressure waves led to a performance recovery of up to 9. This recovery is attributed to the enhanced removal of accumulated water on the GDL surface through external excitation, which facilitated oxygen supply and improved water discharge. The proposed the water management method can offer a promising solution for recovering performance in irreversibly degraded PEMFCs and has the potential to improve both performance and durability.

Acknowledgement

This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. RS-2023-00208497, RS-2023-00219369).

Reference

[1] Kim, J. Y., Mortazavi, M., & Jung, S. Y. (2024). Improving polymer electrolyte membrane fuel cell performance and preventing flooding by exciting gas flow. Journal of Power Sources, 617, 235181.
Pore Uniformity Effect of Porous Transport Layers on Bubble Behaviors in PEM Water Electrolysis
Authors: Kim Seongkeun , Jung Sung Yong 
Published: December 2024

Hydrogen, a clean energy source with high energy density and long-term storage potential, is gaining attention as a viable alternative to fossil fuels. Among various water electrolysis methods, Proton Exchange Membrane Water Electrolysis (PEMWE) is suitable for green hydrogen production due to its ability to operate efficiently at high current densities and low temperatures. A key component of PEMWE is the Porous Transport Layer (PTL), which facilitates oxygen gas discharge and water supply. However, to enable practical use of PEMWE at high current densities, effective oxygen removal without accumulation in the PTL is critical. While previous studies have explored the structural characteristics of PTL, research quantifying the effect of PTL pore uniformity on PEMWE performance remains limited. This study compared PTL samples with different pore uniformities using X-ray CT, investigated how these differences affect PEMWE performance, and analyzed bubble detachment characteristics on the PTL surface using high-speed imaging.
A specially designed cell with a transparent acrylic end plate was used to observe internal flow in the PEMWE system. The bubble detachment characteristics, including the number, frequency, and diameter of detached bubbles, were analyzed. The homogeneous PTL followed a normal distribution, while the inhomogeneous PTL exhibited a broader pore size range, deviating from this distribution. These structural differences led to significant performance variations. The homogeneous PTL had a bubble detachment rate of 9.49 bubbles/mm2, with an average detachment frequency of 30.5 Hz and a detachment diameter of 2.21 mm. In contrast, the inhomogeneous PTL exhibited a significantly lower detachment rate of 0.30 bubbles/mm2, a higher detachment frequency of 78.2 Hz, and a larger detachment diameter of 22.4 mm. Furthermore, when comparing the departure velocity, calculated by multiplying the detachment frequency by the bubble diameter, the homogeneous PTL achieved a velocity of 289.3 mm/s, approximately 3.2 times faster than the 89.6 mm/s observed in the inhomogeneous PTL. These findings suggest that a more uniform pore structure enables faster and more efficient gas removal, leading to enhanced PEMWE performance. Additionally, the high departure velocity in the homogeneous PTL indicates a more effective two-phase flow, which contributes to the improved water supply and gas discharge, thereby optimizing overall cell efficiency.
The homogeneous pore structures promote efficient gas discharge and water supply, leading to improved cell performance. These findings show the importance of designing PTLs with uniform internal pore structures to optimize PEMWE operation.

Acknowledgment

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. RS-2023-00208497, RS-2023-00219369).