bluuebunny/crossref_metadata_2025 huggingface dataset:
Large-Scale Production of Nanotube Silicon for Lithium-Ion Batteries
Authors: Manwaring Kyle Charles , Gonda Brian , Parise Cale , Garcia Lizbeth Zurita , Sun Fei , Adhikari Kobit , Wheeler Dean , Mazzeo Brian A.
Published: December 2024

Silicon’s relatively high energy density in comparison to the more common anode material, graphite (3580 mA h g-1
for silicon compared to 371 mA h g-1
for graphite) has made silicon an intriguing anode material for lithium-ion batteries. However, during lithiation, the volume of silicon increases by approximately 300% causing irreversible capacity loss. During the initial charging of an anode, a solid electrolyte interface (SEI) forms on the surface of the anode. The formation of the SEI consumes lithium, resulting in irreversible capacity loss. The large volume expansion of silicon can break the SEI layer. This results in a new SEI layer needing to be formed and further irreversible capacity loss. In addition, the expansion of the silicon particles can lead to silicon particles being isolated from the anode where they can no longer participate in the charging and discharging process, lowering the capacity of the anode. To accommodate for this large volume expansion, silicon nanoparticles on the scale of 50 microns are often used to accommodate for the large volume expansion and help retain capacity. Silicon nanotubes provide additional benefits such as increased structural stability, faster lithium-ion diffusion, and greater electrical conductivity than silicon nanoparticles.

This work details a process to produce silicon nanotubes from halloysite on a large scale. Halloysite is an alumina-silica-based structure composed of natural nanotubes. Silicon can be obtained from halloysite by etching off the alumina components and further reducing the silica to silicon through a magnesiothermic reduction. However, both the etching step and reducing step are very exothermic. If the heat transfer is not controlled correctly, the heat released during these reactions can destroy the natural tube structure. The reaction temperature is dependent on a variety of variables including: reactor temperature, ramp rate, addition of salts, and quantity of reactants. The processes and parameters used to successfully manage the heat released as a part of scale up this process are described. BET and SEM imaging were used to determine the surface area and structure of the produced silicon. In addition, the electrochemical performance of the silicon was tested and investigated in patch cells.

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Achieving Market-Ready Economic and Environmental Feasibility of Biomass-Based Plastic, Polyethylene Furanoate (PEF), via Electrocatalytic Conversion of Crude 5-Hydroxymethyfurfural (HMF) Solution
Authors: Lee Dong Ki , Woo Jongin , Lee Ung , Han Donggu
Published: December 2024

Polyethylene furanoate (PEF) has excellent physicochemical properties among biomass-derived plastics, and its applications are expanding beyond food and beverage packaging to textiles, films, and 3D printings. Nevertheless, commercialized large-scale production of PEF has yet to be accomplished due to the high cost of FDCA (2,5-furan dicarboxylic acid), the monomer of PEF. FDCA is synthesized via selective carboxylation of 5-hydroxymethyl furfural (HMF), and the use of high purity HMF (>99%) is essential to obtain polymerizable purity of FDCA. HMF is synthesized by strong acid saccharification and dehydration/isomerization of cellulose, and various by-products and unreacted sugars coexist during the synthesis process. Consequently, the purification and separation process is necessary to obtain the high-purity HMF, which significantly increases the production cost. In this presentation, I present the electrochemical production of high-purity FDCA from unrefined HMF solution, which is about 8 times cheaper than 99% HMF, without a purification process. The techno-economic analysis (TEA) life-cycle assessment (LCA) analyses demonstrate that the electrochemical synthesis of FDCA from crude feedstock not only makes it cheaper than a thermochemical process that can only utilize high-purity HMF, but also significantly reduces carbon emissions. In addition, the principle of the electrocatalysis that selectively converts HMF to FDCA while harmlessly removing impurities from the unrefined HMF solution was investigated by in-situ/operando X-ray absorption spectroscopy (XAS) and attenuated total reflection-Fourier transform Infrared Spectrometer (ATR-FTIR) analyses.
(Invited) Multi-Physics Modeling of Electrochemical Interfacial Phenomena
Authors: Viswanathan Venkatasubramanian
Published: December 2024

In this talk, I will discuss our simulation approach which is based on creating an end-to-end differentiable simulation stack for electrochemical phenomena and corresponding validation from 1nm - 1mm. DFT simulations, paired with molecular dynamics, chained to phase-field simulations which are then integrated through reduced-order models in pseudo-2D simulations, enabling simulation capability of interfacial phenomena in a fully differentiable way. I will discuss these results in the context of solid-state batteries.
(Invited) EIS Measurements in Ionic Liquids: Monitoring of the Electrodeposition of a Thin Metal Layer
Authors: Kurchavova Ekaterina , Xie Yuelin , Vivier Vincent , Turmine Mireille
Published: December 2024

Ionic liquids are increasingly used in a variety of applications, including electrolytes for electrochemical devices, solvents for the electroplating of thin metal layers, and corrosion inhibitors. Ionic liquids are a broad family of solvents whose physicochemical properties (viscosity, conductivity, etc.) depend on the nature of the anion and cation that form them. Some are protic with a labile proton, others are non-protic. Electrodeposition of metal in a protic ionic liquid such as ethylammonium nitrate (EAN) can be carried out at ambient temperature whereas higher temperatures are frequently performed in a non-protic ionic liquid. In addition, the electrodeposition of several elements is simple, yielding to an alloy whose composition and morphology are determined by the electroplating conditions. In this presentation, we will show how Electrochemical Impedance Spectroscopy (EIS) which is an efficient technique for characterizing the solid-liquid interface and investigating the electrodeposition mechanisms, can help for working in these media.

In a first part, we will look at the electrodeposition of Nickel, Cobalt and their mixtures in EAN, a pure protic ionic liquid, and discuss EIS results. In a second part, we will take advantage of the low vapor pressure of ILs, and we will discuss how we can characterize a material reactivity by performing electrochemical measurements in a 3 - 5 µL drop of ionic liquid.
(Invited) Atomic Layer Deposition of “Group 16 Compounds” for Emerging Applications
Authors: Kim Hyungjun
Published: December 2024

The exclusive benefits of atomic layer deposition (ALD), including excellent conformality over nanoscale complex structures, high quality of deposited films even at low temperature down to room temperature, atomic scale thickness controllability, and high uniformity over nanoscale structure, make it viable tool for many emerging applications. Among varous materials which can be prepared by ALD, Group 16 compounds, including oxides and chalcogenides, are most widely studied materials group, which are very important for nanoscale device fabrications and other emrging applciations. In this presentation, I will summarize the process and applciaitons of emerging oxides and chalgogenides. Especially, focus will be given to two dimensional (2D) transition metal dischalcogenides (TMDCs) nanosheets, since they have exotic electronic and optical properties: Indirect-to-direct bandgap transition depending on the number of layers, high carrier mobility and strong spin-orbit coupling due to their broken inversion symmetry. In contrast to conventional chemical vapor deposition (CVD), ALD makes it a promising synthesis method for 2D TMDCs. I will present the synthesis of various 2D TMDCs nanosheets including MoS2, WS2, WSe2 and their alloys such as Mo1-xWxS2 based on ALD process. Also, various appliations of these materials will be presented such as gas sensors and catalysis for hydrogen evolution rate. In addition, ALD for other related materials including other 3D chalcogenides such as GeS, RuS2 and carbon. Basic growth charateristics and applilcations for ovonic threshold switwching (OTS), Lidar and next generation patterning tehnology will be presented.
(Invited) Faster ALD for Emerging Quantum Applications
Authors: Kurek Agnieszka , Besprozvannyy Dmytro , Saha Arpita , Shu Yi , Powell Michael , Lennon Ciaran , Knoops Harm
Published: December 2024

Plasma Atomic Layer Deposition (ALD) enables the deposition of a wide variety of materials, with nanometre-scale resolution and precision. Self-limiting growth is a keystone characteristic of ALD processes but limits deposition rate. Long cycle times and low growth per cycle (GPC) impose practical limits on how thick ALD films can be grown. In the field of Quantum Technology (QT), superconducting nanolayers are required for use in Single-Photon Detectors (SPDs), superconducting qubits and interconnects for quantum computing.1 Some superconducting interconnects benefit from non-planar connectivity to control qubits,2 and 3D architectures are key for scaling larger arrays of qubits.3 The deposition of high-quality materials on high aspect ratio Through-Silicon Via (TSV) interconnects is essential but difficult to achieve by conventional sputter techniques. Superconducting nitrides in some QT applications demand relatively thick films (>50 nm), and this poses a new challenge for ALD: to maintain desirable film characteristics and grow thick layers much faster. Here we present recent developments from our new R&D ALD platform: PlasmaPro ASP.

The design of the remote, RF-driven plasma source has been optimised to deliver quick, repeatable plasma doses to the substrate with minimal plasma damage. The chamber size, pumping and precursor delivery have been carefully considered to enable efficient ALD of many materials. For multiple materials, we have demonstrated a reduction of cycle times. For example, rates of >25 nm/h for NbN and TiN which is about 3x faster than previously reported. Importantly, these materials retain excellent film properties. NbN showed excellent electrical resistivity (four-point probe), conformality (100% on 8:1 trench), and superconducting transition temperature (Tc) >11 K for <10 nm thick films – a key regime for SPDs. NbN and TiN crystallinity, film stress and film composition will be discussed. Furthermore, many other applications will benefit from this fast plasma ALD. We will also present plasma Al2O3 for power electronics which has been deposited on substrates of up to 200 mm in diameter with a less than one second ALD cycle time. As the needs of emerging quantum technologies and other applications change and continue to push process and film performance, production and research will benefit from high-quality, low damage, conformal films by fast, remote plasma ALD.

References:

Giustino et al., J. Phys. Mater. 3, 042006 (2021)

Kjaergaard et al., Annu. Rev. Condens. Matter Phys. 11, 369 (2020)

Yost, et al. npj Quantum Inf 6, 59 (2020)
Growth of High-Quality Non-Polar Materials through Graphene via Anchor Point Nucleation
Authors: Hanus Tadeas , Diallo Thierno Mamoudou , Ruediger Andreas , Harmand Jean-Christophe , Patriarche Gilles , Boucherif Abderraouf
Published: December 2024

The application of 2D-assisted epitaxy in the growth of freestanding membranes, hybrid 2D/3D heterostructures, and direct integration of highly mismatched materials has sparked significant interest in fields such as electronics, optoelectronics, and quantum devices. This method has been utilized for the growth of variety of materials, including III-N and III-V semiconductor compounds, various oxide compounds, perovskites, metals, and 2D materials, demonstrating its tremendous potential. However, one of its major challenges remains the growth of non-polar materials like Ge. This is mainly due to the minimal interaction between non-polar materials and 2D interface or underlying bulk substrate. This makes the nucleation and crystal orientation of epilayers very difficult, resulting in polycrystalline structures.

In this study, we unravel the key mechanisms governing the nucleation and growth of 3D non-polar materials on suspended single-layer graphene (SLG) from real-time observations of the growth by using in-situ Transmission electron microscopy (TEM)[1]. This powerful technique provides a unique opportunity to observe new and yet unexplored phenomena, which are not accessible to the standard ex-situ characterizations. Through direct observations, remote interactions are elucidated between Ge crystals through the graphene layer in double heterostructures of Ge/graphene/Ge. Based on these findings, we implemented a novel approach for growth of non-polar materials by 2D-assisted epitaxy, called “anchor point nucleation”[2]. This method involves the engineering of the SLG substrate, by introducing defects that act as preferential nucleation sited for the epitaxial growth and aid orienting the epilayer by the underlying substrate. Figure 1 illustrates this approach.

The engineering of the SLG was achieved through plasma treatment, and the effects of the treatment duration were analyzed by using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Experimental data confirmed the introduction of defects after the treatment, leading to an increase in nucleation sites shown by the increasing number of Ge nuclei on the treated SLG. These observations corroborate the pivotal role of induced defects in the nucleation process, enhancing surface energy and the reactivity of graphene. The high quality of the resulting epitaxial layers is demonstrated through TEM and electron backscatter diffraction (EBSD) characterizations. These findings mark the first demonstration of anchor point nucleation enabling high-quality growth of non-polar semiconductors through 2D-assisted epitaxy.

[1] T.M. Diallo et al., Small (2022), 18, 2101890. (https://doi.org/10.1002/smll.202101890)

[2] T.M. Diallo, T. Hanuš et al., Small (2023), 20, 2306038 (https://doi.org/10.1002/smll.202306038)

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Optimizing High Energy Density Sulfur Cathodes: A Multivariate Approach to Electrode Formulation and Processing
Authors: Anderson Cassidy , Lu Dongping
Published: December 2024

Lithium-sulfur (Li-S) batteries involve complex solid-liquid-solid phase transformations during both discharging and charging processes, where cathode materials, formulation, and structure play a crucial role. Here, a design of experiments (DoE) methodology and an empirical model are developed to systematically explore the interactions and trade-offs among cathode factors and process variables, and to obtain generalizable effects estimates for the multivariate system. Compared to the conventional one-factor-at-a-time (OFAT) approach, this work demonstrates advantages in both efficiency and accuracy by allowing the data to guide future research and decisions. An optimized cathode formulation and processing is predicted and validated experimentally, achieving over 1000 mAh g-1 in discharge capacity and improved cycling under practical lean electrolyte (4 µL mg-1 S) and high S-loading cathodes (>4 mg cm-2) conditions. The optimized cathode was scaled up and assembled into Li-S pouch cells, achieving 316 Wh kg-1 in cell level energy, proving that the comprehensive and rigorous framework for optimizing complex systems with DoE leads to improved performance in a practical pouch cell system.
(Invited) Why Poly-OS IGO TFT Exhibits Mobilities >50 cm2/Vs
Authors: Tsuruma Yuki , Yamaguchi Koji , Sasaki Daichi , Kawashima Emi , Kadono Tasuke , Ide Keisuke , Katase Takayoshi , Kimura Mutsumi , Kamiya Toshio
Published: December 2024

Poly-OS, a poly-crystalline oxide semiconductor, is one candidate for providing high-mobility backplane thin-film transistors (TFTs) for flat panel displays. Existing amorphous oxide semiconductor (Oxide) TFTs, like amorphous silicon (a-Si) are easy to fabricate in large areas. In addition, Oxide offers low power consumption due to their low off-leakage current. On the other hand, they have lower mobility than low temperature poly-crystalline silicon (LTPS), which is mainly used in today's small- and medium-sized displays. Poly-OS technology significantly improves mobility and enables high performance comparable to LTPS. This makes it possible to create products that combine the performance of existing backplane technologies (a-Si, Oxide, and LTPS) In fact, TFT mobility of 55.7 cm2/Vs has been achieved on a large-area substrate of the G6(1500×1800 mm) line by its sophisticated technology1 and IGO2 including indium, gallium and oxygen which one of Poly-OS material developed by us.

IGO is characterized by its ability to generate a poly-crystalline state using the conventional process (450 ℃ or lower) like existing oxide semiconductors. By using this poly-crystalline structure in the active layer, it is possible to maximize the inherent electron mobility of oxides. X-ray diffraction peaks observed in IGO film are in good agreement with the In2O3 crystalline bixbyite structure (space group Ia-3), and cross-sectional TEM and the fast Fourier transform (FFT) pattern indicate that the film has single crystal structure in a grain. Hall mobility(μ
H) of IGO films is remarkably higher than that of amorphous Oxide in high carrier concentration: nH
region (> 1 × 1019 cm-3). The μ
H - nH
trend is important in considering the field-effect mobility for carriers accumulated by the gate electric field. As a result, it is expected that IGO TFT which has carrier concentration more than 1 × 1019 cm-3 by the gate field exceed the mobility of 50 cm2/Vs.

We will explain why poly-OS exhibits high TFT mobilities over 50 cm2/Vs despite it exhibits μH
as low as 20 cm2/Vs when nH
corresponds to those used in TFT channels.

References:

1) M. Tsubuku, et. al. SID 2023 DIGEST 8-1, 78-81 (2023).

2) https://www.idemitsu.com/jp/news/2022/220621.html

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(Keynote) Wafer-Scale Epitaxy of 2D Materials with Uniformity, Single Crystallinity, and Low Defect Density
Authors: Tung Vincent
Published: December 2024

Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) representing the ultimate thickness scaling of channel materials provide a solution to tantalizingly push the limit of technology nodes in the sub-1-nm range. One key challenge with 2D semiconducting TMDs channel materials is the large-scale batch growth on insulating substrates with continuous single crystallinity, spatial homogeneity, and compelling electrical properties. Recent studies have claimed the epitaxy growth of wafer-scale, single-crystal 2D TMDs on C-plane sapphire substrate with deliberately engineered off-cut angles. It has been predominately postulated that exposed step edges break the energy degeneracy of nucleation and thus drive the seamless stitching of mono-oriented flakes. In this talk, I will show that a more dominant factor should be considered. The interaction of 2D TMD grains with the exposed oxygen-aluminum atomic plane establishes an energy-minimized 2D TMD-sapphire configuration. Reconstructing the surfaces of C-plane sapphire substrates to only a single type (symmetry) of atomic planes already guarantees the single-crystal epitaxy of monolayer TMDs without the aid of step edges. Electrical results also evidence the structural uniformity of the monolayers. Our new experimental findings elucidate the long-standing question that curbs the wafer-scale batch epitaxy of 2D TMDs single crystals, an essential step toward using 2D materials for future electronics. Experiments extended to other materials like perovskites also support the argument that the interaction with sapphire atomic surfaces is more dominant than the step edge docking.
(Invited) Designing Noncentrosymmetric and Chiral 2D Quantum Materials Via Screw Dislocations and Structural Tuning
Authors: Jin Song
Published: December 2024

Rationally controlling the structures of two-dimensional (2D) materials allows us to tune the eelectronic structures and quantum states of matter, discover new physical properties, thus enabling new applications. Noncentrymmetry of these MX2 materials and 2D halide perovskites could be enabled at the monolayer and bulk crystal structure level by structural tuning and screw dislocation growth to result in chiroptical properties of individual chiral spiral microplates. Moreover, we achieved systematic interlayer twisting of MX2 spiral layers grown via screw dislocations due to mismatched geometry between Euclidean crystal lattices and non-Euclidean (curved) surfaces to form moiré superlattices, which could lead to novel quantum phenomena. Beyond optoelectronic applications, the large spin-orbit coupling in highly tunable 2D hybrid halide perovskites can lead to Rashba and/or Dresselhaus spin splitting and make them promising for spin-orbitronic applications. We utilize the complex interplay between the organic spacer cations, the A-site cations, metal cations and dimensionality to produce non-centrosymmetric structures that exhibit ferroelectricity, Rashba splitting and persistent spin textures. These rational design strategies to unlock and control non-centrosymmetry, chirality, and twist of 2D materials open up new nonlinear and chiral optical properties, spin-orbitronic, twistronics, and neuromorphic applications.
(Invited) A Polaron Paradigm for Perovskite Nanocrystal Emitting States
Authors: Kuno Ken
Published: December 2024

Perovskite nanocrystals (NCs) such as those made from CsPbBr3 have numerous uses. Most involve exploiting their light emission and are motivated by their defect tolerance and large, as-made emission quantum yields (QYs). For the latter, near unity QYs are possible. This leads to ready applications as light emitters but also intriguingly to possible material platforms for demonstrating semiconductor-based optical refrigeration.

Absent, though, is a fundamental understanding of perovskite NC emitting states, central to these applications. Of particular note are observations of near-universal, size-, temperature-, and composition-dependent absorption/emission Stokes shifts where observed energy differences are those that separate absorbing and emitting states. Moreover, efficient (near-unity efficiency), photoluminescence up-conversion, induced by exciting NCs below gap, motivates better understanding the microscopic nature of perovskite band edge states.

I will explain work we have done recently within the context of attempts to optically refrigerate a semiconductor. These studies now provide new insight into the band edge states of CsPbBr3 (and possibly CsPbX3) NCs. Starting with a microscopic mechanism for explaining how it is possible to obtain efficient, near-unity efficiency photoluminescence up-conversion to we extend the conclusions of these measurements to explain the origin of observed, size-dependent absorption/emission Stokes shifts. Here, despite some initial studies we and others have conducted, very little is known about their true origin. This is to be contrasted to more conventional NCs such as CdSe where band edge exciton fine structure quantitatively accounts for both global and resonant Stokes shifts, with emission emerging from a dark exciton. Although similar perovskite NC fine structure might account for their shifts, both theory and experiment predict bright/dark fine structure splittings easily an order of magnitude too small to account for experiment.

We now propose that perovskite NC emitting states are polarons, which result from the lattice accommodation of photogenerated charges. Polaron binding energies and lifetimes are, in turn, suggested to be the origin of observed l-, T-, and composition-dependent absorption/emission Stokes shifts and excited state lifetimes. This represents a significant departure from more conventional descriptions of NC band edge states, which exclusively involve exciton fine structure and dark exciton emitting states.
(Invited) Sustainable Green Quantum Dots in Catalytic and Photovolatic Applications
Authors: Naccache Rafik
Published: December 2024

Quantum sized nanomaterials have garnered significant interest owing to their versatile properties with a vast potential in sensing and imaging applications, in optoelectronics, catalysis, as well as energy conversion. Their ultra-compact size, low cytotoxicity, low photo-bleaching/blinking, tunable photoluminescence, combined with simple, environmentally friendly and low-cost synthesis, makes them ideal and cost-efficient candidates for study. In this work, we discuss the synthesis of green quantum dot nanomaterials, both organic and inorganic, via a myriad of techniques including solvent mediated and solid-state bottom-up synthesis methods, with simple starting materials. We focus our efforts on tailoring their physico-chemical and optical properties and exploit them in order to design multifunctional materials for clean energy including conversion of waste oils to biofuels, as well as their integration in photovoltaic solar cells. The luminescent properties of these nanomaterials also find applications as optical based and bio-based sensors.
Polymer Electrolyte Fuel Cells Using Powerpaste
Authors: Bencomo Natalia , Lambourne Devon , Lynn Zachary , Matter Paul , Ocampo Minette
Published: December 2024

Heavy duty vehicles are responsible for 30% of all transportation emissions (1.8 GtCO2-eq).1Therefore, electrification of heavy-duty transportation is urgently needed. However, heavy-duty PEM fuel cells operate under much harsher conditions than light duty fuel cells and are expected to last much longer in the field. These systems must operate successfully in the presence of impurities, starting and stopping, freezing and thawing, humidity and load cycling. Therefore, materials, components, and interfaces used in such systems must be highly resistant to severe mechanical and chemical stress. Furthermore, large systems such as planes, ships and trains need large amounts of fuel, i.e., a high-energy density fuel packaging for hydrogen is required. Fraunhofer’s magnesium hydride (MgH2) paste, POWERPASTE, is 90% H2, does not require a high-pressure tank and is safe to store in cartridges. The paste releases hydrogen when mixed with water and can be recycled back to MgH2. However, integration of POWERPASTE with fuel cell vehicles has not yet been established.

Giner will therefore develop US made propulsion systems using this high-power density fuel to electrify planes, ships and trains. To achieve energy density targets that equal or exceed 1,000 watt-hours per kilogram and 1,000 watt-hours per liter at the end of life, Giner will evaluate a suite of best-in-class catalyst, ionomer, and membrane materials to find the best performing fuel cell configuration. This includes novel, highly active stable PtCo catalysts with well-controlled particle size and composition, such as pH Matter’s PtCo/MFCS-C catalyst, which have been synthesized for enhanced fuel cell performance and durability at dry conditions, eliminating the need for a humidifier. Initial performance testing will be followed by long term accelerated stress tests on small scale membrane electrode assemblies (MEAs).

Acknowledgement: The project is financially supported by the Department of Energy’s ARPA-E Office (Phase I Grant).

1. “Electric Vehicle Outlook 2022” BNEF https://bnef.turtl.co/story/evo-2022.

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Synthesis of Transition Metal Carbide Catalysts for Hydrogen Evolution Reaction
Authors: Qi Jing , Zhai Yunfeng , Bethune Keith
Published: December 2024

Water electrolysis is one of the most promising ways for hydrogen production. Transition metal carbides are regarded as potential candidates to replace state-of-art but expensive platinum-group catalysts for hydrogen evolution reaction (HER). Considering the excellent electrochemical stability of TiC, a bimetallic VTiC with minor percentage of Ti would increase stability. Vanadium carbides were prepared from commercially available TiC as carbon sources and supports at 1000°C (denoted as VxTiC-1000°C) and 1100°C (denoted as VxTiC-1100°C). As shown in Figure 1a, VxTiC-1000°C and VxTiC-1100°C are a mixture of V8C7 and (Ti0.3V1-0.3)2O3 phases. While VxTiC-1000°C contains some unreacted TiC. Figure 1b shows numerous flakes grown on the particle surface of VxTiC that are expected to possess extremely large surface area. There is no phase change for VxTiC before and after treated in 3 M H2SO4 at 80 °C which means that VxTiC is acid resistant. Stability tests for VxTiC performed in 0.5 M H2SO4 up to 1.4 V exhibit excellent electrochemical stability and catalytic activity of VxTiC toward HER.

Figure 1. (a) X-ray diffraction patterns and (b) scanning electron microscopy image of VxTiC.

Acknowledgments

Authors are grateful to the Office of Naval Research (award N00014-19-1-2159, N00014-120-1-2270).

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High current density operation of proton exchange membrane fuel cells at a constant relative humidity
Authors: Liu Wei , Zhong Zhaoda , Liso Vincenzo , Berning Torsten
Published: December 2024

In order to further reduce the size and cost of proton exchange membrane fuel cells, it is desired to operate at high current densities exceeding 2 A/cm2, and consequently achieve high power densities well above 1 W/cm2. In prior work, it was found that proton exchange membrane fuel cell might operate at current densities as high as 10 A/cm2 and even more when appropriate operating and channel dimensions are chosen, and perforated metal plates are used instead of carbon fiber papers as porous transport layers. The underlying idea was to operate such a fuel cell at 100% relative humidity (RH) from cathode inlet to cathode outlet, taking advantage of the fact that the pressure drop along the channel leads to a reduced RH while the addition of water and consumption of oxygen leads to an increase in RH. In a one-dimensional modeling study employing the Engineering Equation Solver (EES), appropriate boundary and operating conditions were identified, and the general finding was that a lower operating temperature and a shorter channel led to a higher limiting current density. The current study verifies the accuracy of the previous 1-D model by a 3-D multiphase computational fluid dynamics (CFD) model in Ansys CFX to obtain additional insights. Operating a proton exchange membrane fuel cell at a constant humidity of 100% from the inlet to the outlet at the cathode side is feasible, and results for a current density above 6 A/cm2 and a stoichiometric flow ratio below two were obtained. These results suggest that the pressure drop for such operation is substantially higher than in normal automotive fuel cells, but because of the much shorter channels afforded by the high current density, the overall penalty is small. Overall, this mode of operation appears to be very promising also for automotive fuel cells.
A Multiscale Modeling Approach to Investigate the Influence of Catalyst Layer Materials in Proton Exchange Membrane Fuel Cells
Authors: Jahnke Thomas , Gülicher Konrad , Mitzel Jens , Morin Arnaud
Published: December 2024

In order to enable a simulation-based improvement of the MEA design, detailed physical models are required which accurately describe all relevant processes. This poses a major challenge as these processes span over about 10 orders of magnitude from the atomistic scale up to the cell and stack scale. In order to simulate the cell performance, volume averaged models are needed which describe the mass-, charge- and energy transport as well as the electrochemical reactions. The required transport and kinetic parameters are often unknown and material dependent. Therefore, lower scale models and dedicated experiments are required to determine these material dependent properties.

In this work we present a multiscale model developed within the project FURTHER-FC [1] which takes into account the microstructural properties of the cathode catalyst layer and GDL/MPL. Lattice Boltzmann modeling is used to derive the local oxygen transport resistance in the CCL on the sub-µm scale, while the effective transport properties through the thickness of the CCL and the GDL/MPL are obtained from DNS [2]. On the cell scale a 2D along-the-channel volume averaged model is developed which, in addition to the relevant transport processes, includes the contributions of inner and outer platinum particles to the ORR as well as the effect of ionomer poisoning. A thorough model validation is conducted where a particular focus is put on the hysteresis observed in polarization curve measurements as well as on the impedance spectra. The model is applied to MEAs with different catalyst layer materials and the effect of high surface area carbon (HSAC) vs. graphitized carbon as well as HOPI vs. D2020 as ionomer is investigated.

Figure: left: comparison of MEAs with HSAC and graphitized carbon at 80°C, 80%RH, 2 bar and 0.2 bar O2 ; right: model validation with impedance simulations for graph. carbon MEA

The project FURTHER-FC has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under Grant Agreement No 875025. This Joint Undertaking receives support from the European Union’s Horizon 2020 Research and Innovation program, Hydrogen Europe and Hydrogen Europe Research.

[1] https://further-fc.eu/

[2] M. Ahmed-Maloum et al., Journal of Power Sources 561 (2023) 232735

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The Effect of Crystal Structure of Si Anode on Electrochemical Properties for Lithium-Ion Batteries
Authors: Yang Minji , Shim Jae-Hyun
Published: December 2024

Silicon anode attention as a promising next-generation anode material capable of achieving high capacity/high density lithium-ion batteries, possesses the advantage of an extremely high theoretical capacity of 3,800 mAh/g. Si anode materials are known to experience volume expansion of about 400% during charging and discharging, leading to material cracking as a consequence. Therefore, in order to effectively utilize Si anode materials, it is necessary to mitigate the volume expansion issue by designing materials with lower expansion. For this, understanding the electrochemical mechanism differences of Si anode materials according to their crystal structure is crucial.

In this study, Si is synthesized using the RF thermal plasma synthesis technique. Using the synthesized Si anode material, fabricate SLP(single layer pouch type) cells and evaluate their electrochemical characteristics such as cyclability at room temperature and high temperature, C-rate, impedance and swelling. The results of the electrochemical characterization will be compared and analyzed, and compare materials with maximum and minimal expansion rates based on differences in crystal structure.

To analyze the irreversible phases related to the crystal structural differences during initial charging and discharging processes, Si 100% coin half cells be fabricated for ex-situ XRD analysis. Additionally, for more precise analysis, TEM analysis technique employed for comparative analysis.
In Situ Multi-Site Plasma Focused-Ion-Beam Tomography on Li-Electrolyte Interface in All-Solid-State Batteries
Authors: Risal Samprash , Milapati Sanam , Fan Zheng
Published: December 2024

All-solid-state lithium metal batteries, poised to deliver one of the highest specific energy among rechargeable batteries, establish themselves as a front-runner for next-generation electric vehicle batteries; nevertheless, realizing high-performance solid-state Li batteries remains challenging due to the high impedance and (for the anode side) uncontrolled Li deposition at the interfaces between active electrode materials and solid electrolytes. The lack of direct and quantitative characterization tools for the active material−electrolyte interfaces has been a major hurdle towards high-performance solid-state batteries. Most studies had to rely on indirect characterization methods to approximate the identity, distribution, and evolution of species and structures at the interfaces. This work demonstrates a combined diagnostics of the interfaces and their evolutions during cell operation using in situ multi-site plasma focused-ion-beam (pFIB) tomography.

Utilizing the advanced capabilities of pFIB technology, which offers significantly higher material removal rates compared to gallium-based systems, we significantly reduce the duration of tomography sessions. This efficiency enhancement not only accelerates the morphological data acquisition but also supports the continuous and multi-site application of pFIB tomography on a single specimen through its electrochemical reaction cycle. In this experiment, the Li-electrolyte interface within a trilayer battery structure (Li/electrolyte/NMC-electrolyte composite) was characterized in situ at multiple sites using FIB. The tests were performed in a custom-built transfer vessel equipped with an in situ testing platform, enabling air-free specimen transfer from an argon-filled glovebox to the pFIB-SEM setup. This system also facilitates in situ charge/discharge cycling under simulated real-world conditions, including environmental stimuli like heating and pressing. The open-cell design of the battery specimen on this platform, with exposed and polished interfaces, provides direct visibility into the interface dynamics that is comparable to traditional Swagelok-cell setups but with enhanced observational capabilities.

The resultant tomography models from the Li-electrolyte interface during charging and discharging cycles elucidate the structural evolution of the components under different operational statuses. Key observations include the initiation, growth, and interaction of Li dendrites within the electrolyte layer, and the development of voids at the Li-electrolyte interface, particularly their dynamics during battery operation. While these phenomena have been extensively studied using other diagnostic techniques, the application of in situ multi-site pFIB offers unprecedented insights into the morphological changes induced by battery cycling, thereby contributing to a comprehensive understanding of the failure mechanisms in solid-state batteries.
Design Rules for Optimizing Microporous Layer Properties and Back-Layer Effect Using Decal Transfer Method in PEMWE
Authors: Jung Gi Hong , Park Hyeonjung , Lee Sechan , Lee Changsoo , Kim MinJoong , Cho Hyun-Seok , Doo Gisu
Published: December 2024

Polymer electrolyte membrane water electrolysis (PEMWE) has the fatal drawback of using expensive noble metal catalysts, especially the rare iridium substances in the anode. Therefore, improvements in catalyst utilization are required to achieve high performance and durability even at a minimized use of catalyst. One option is introducing a titanium-based microporous layer (MPL) at the interface of the catalyst layer and porous transport layer (PTL) to create an increased contact area and form a better electrical connection. However, how the MPL should be designed and manufactured is not fully understand yet. Herein, we present a decal-transfer method, which is a convenient process to manufacture a uniform and thin MPL on a porous substrate layer. Based on this method, we investigated the two-phase transport phenomena of the MPL by varying the particle size and thickness of the MPL and the porosity of the substrate layer. It is concluded that a smaller micrometer-scale titanium particle size is advantageous in both catalyst utilization and water transport, resulting in lower kinetic and mass transport overpotential. Furthermore, the interface property acted as the determinant factor for the overall performance, while the bulk property of the PTL was not a critical factor unless it did not hinder the mass transport of oxygen gas in-plane direction.
(Invited) Let’s Roll – the Roll-to-Roll Consortium for Fuel Cell and Electrolyzer Manufacturing
Authors: Mauger Scott A , Serov Alexey , Zhang Yuepeng
Published: December 2024

Proton exchange membrane fuel cell and electrolyzer manufacturing are in the early stages of rapid expansion. Many companies have announced plans for significantly increase their manufacturing capacity through new facilities or expansion of existing facilities. This increase in scale is necessary to achieve system-cost and emission-reduction targets. However, manufacturing speed is not a knob that can simply be turned up to produce high performance, durable systems. Manufacturing processes must be understood and developed to produce fuel cells and electrolyzers that meet the requirements for both throughput and performance.

The U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office (HFTO) has launched a new consortium, the Roll-to-Roll (R2R) Consortium, to conduct process science and engineering research for fuel cell and electrolyzer manufacturing. R2R’s mission is to advance efficient, high-throughput, and high-quality manufacturing methods and processes to accelerate domestic manufacturing and reduce the capital cost of durable and high-performing systems. Three major research thrusts in catalyst synthesis process science, MEA fabrication process science, and quality control are set to address challenges associated with high-volume manufacturing, which is supported by additional activities including the development of characterization tools suited for the needs of the manufacturing environment, process modeling, artificial intelligence and machine learning, and technoeconomic analysis (TEA). The objective of these activities is to enable increased production speed, yield, and efficiency to achieve fuel cell and electrolyzer manufacturing rate and cost targets. This talk will provide an overview of the R2R Consortium’s research activities.
Evaluation of the Performance and Mechanical Stability of PEMFC Single Cell Considering Vibration Characteristics in the Construction Equipment Working Environment
Authors: HAN Kyoungho Ho , Kim Ji San , Park Sang Gyun , Kim Jae Duk , Park Myung Geun , Lee Gi Cheon , Kim Hee Su
Published: December 2024

As the global demand for eco-friendly power sources increases, the adoption of hydrogen fuel cells as a sustainable and environmentally friendly alternative is gradually expanding in the construction equipment sector. Fuel cell technology has already gained significant attention with successful applications in various mobility sectors, including cars, buses, railways, and trucks. However, research in areas requiring extreme environmental conditions, such as construction equipment, is relatively scarce. Construction equipment often operates under high vibration and harsh climatic conditions, necessitating studies on fuel cell performance evaluation in similar environments. Previous studies have shown that applying vibration to hydrogen fuel cells can directly affect their performance, but research targeting construction equipment is very limited. Since vibration is an inevitable aspect of construction sites, research on this topic is essential for the practical application of hydrogen construction equipment. Based on this background, this study aimed to obtain basic data for the development of hydrogen fuel cells for construction equipment that can maintain stable performance even in a vibrational environment, by understanding the performance degradation and structural stability changes of fuel cells under vibration conditions. The fuel cells used in this study were 5 cm × 5 cm PEMFC single cells, and vibration tests were conducted in vertical, longitudinal, and lateral directions using a laboratory-scale shaker. The PEMFC single cells were kept in an operating (ON) state during the experiments, and vibrations that could occur in construction equipment were applied. The performance changes of the fuel cells according to vibration intensity and frequency were measured using constant current analysis, current-voltage (I-V) curves, and impedance analysis methods. Constant current analysis was used to evaluate the voltage stability of the single cell, I-V curves for assessing electrochemical efficiency and optimal operating conditions, and impedance analysis for evaluating electrical properties in electrodes and electrolytes.
Improvement of CO2 Conversion By Infiltration of Metal Additives (Ag, Cu, Ni, Co, and Ce) to Decorate Sr2Fe1.5Mo0.5O6-
δ Cathodes for Solid Oxide Electrolysis Cells
Authors: Lee Yi-Hsuan , Wei Tengruei
Published: December 2024

The transformation of CO2 into CO and its conversion into biofuels has become a topic of interest due to the increasing severity of global warming. Solid oxide electrolysis cells are considered as one type of device to address this challenge. In this study, the cathode used for the electrolysis cell was Sr2Fe1.5Mo0.5O6-
δ (SFM). Surface modification was performed by infiltrating Ag, Cu, Ni, Co, and Ce at an operating temperature of 800 °C. The SFM sample before H2 reduction treatment show a performance of 100 mA/cm2 at 1.6 V, which is significantly lower than the 196 mA/cm2 achieved after reduction treatment. According to the XRD results, the formation of SrMoO4 before reduction could be a factor affecting its performance.

Furthermore, I-V curves were observed for SFM samples that were infiltrated with Ag, Cu, Ni, Co, and Ce before the reduction treatment. The performance of the infiltrated samples was better than that of the untreated SFM sample. Samples infiltrated with Ag and Cu exhibited a turning point at approximately 1.4 V, where the current density decreased significantly with increasing voltage. The Faradaic efficiency results for CO production indicate that the efficiency of Ag and Cu samples without reduction treatment significantly decreased at voltages above 1.4 V. This phenomenon was not observed in pure SFM samples. It is suggested to be due to the partial supply of current after 1.4 V was not utilized for CO2 reduction but rather for the reduction of Ag and Cu oxides.

Samples treated with H2 exhibited a significant increase in current density. Additionally, the turning point phenomenon observed in Ag and Cu samples was eliminated. SrMoO4 in SFM disappears after reduction treatment. Additionally, the Ag and Cu oxide particles involved in the reaction transform into nano-metal particles that no longer consume supplied electrons. Thus, the Faradaic efficiency results after reduction treatment were higher than that of the pure SFM sample. The Ag sample achieved conversion efficiencies of up to 90%.