bluuebunny/crossref_metadata_2025_split huggingface dataset:
Suppression of the Leidenfrost Effect By Controlling the Nanostructure of Aluminum Surfaces
Authors: Noguchi Takahiro , Iwai Mana , Kitano Sho , Fushimi Koji , Habazaki Hiroki 
Published: December 2024

The Leidenfrost effect is a phenomenon in which a liquid droplet forms a thin film of its vapor on a substrate hotter than the boiling point, causing the droplet to float above the hot substrate. The vapor film inhibits heat transfer between the droplet and the substrate, which reduces the cooling efficiency when the droplet cools the high-temperature substrate. It has been known that the Leidenfrost effect can be suppressed by forming nano- and micro-scale pillars and spikes on the substrate surface [1, 2]; however, conventional methods of constructing nano- and micro-structures require expensive equipment and the process is complicated. Anodic porous alumina films with self-ordered cylindrical nanopore channels can be fabricated on aluminum substrate simply by anodizing in appropriate aqueous electrolyte solutions. The structure parameters of porous alumina, such as pore size, interpore distance, and pore length, can be easily controlled by anodizing voltage and time. This study demonstrates that the anodic porous alumina films can be applied to control the Leidenfrost effect.
Ultrasonically cleaned and electropolished Al plates (99.999%, 1.0-mm thick) were used as specimens. The specimens were immersed in 0.3 M sodium tetraborate solution (343 K) and anodized at 10-200 V for 60 min. The nanostructure of the anodic porous alumina was observed by SEM. The static contact angle of the specimen was measured with a contact angle meter. The behavior of water droplets on the specimen at 473 K was captured by a high-speed camera. The temperature of the specimen was measured using a thermal imaging camera.
Constant voltage anodizing of Al resulted in the formation of porous alumina films with numerous pores. As the anodizing voltage was increased, the pore size increased, with an average pore size of 294 nm at 200 V (Fig. 1a). The static contact angle of the anodized surface became smaller as the pore size increased.
Fig. 1b shows snapshots of the behavior of a water droplet (6 μL) on a smooth aluminum surface at 473 K. The water droplet bounced after dropping and took a long time to evaporate due to the Leidenfrost effect. On the other hand, when the same experiment was performed on the surface of an anodized specimen, the water droplets wetted and spread immediately after contact with the substrate and evaporated in about 50 ms while splitting into fine droplets (Fig. 1c). The surface temperature after dropping the water droplet (12 μL) decreased significantly on the porous alumina with large pores. Therefore, the formation of anodic porous alumina film on the substrate surface effectively suppresses the Leidenfrost effect, suggesting that increasing the pore size can improve the substrate cooling efficiency.
[1] H. Kim, B. Truong, J. Buongiorno, L. W. Hu, Applied Physics Letters, 98, 083121 (2011).
[2] C. Kruse, T. Anderson, C. Wilson, C. Zuhlke, D. Alexander, G. Gogos, S. Ndao, Langmuir, 29, 9798-9806 (2013).

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(Invited) Early Insights, Safer Outcomes - Advancing Battery Safety from the Ground up
Authors: Torres-Castro Loraine , Bates Alex Martin , Johnson Nathan , Albertus Paul , Jeevarajan Judith , Mukherjee Partha P. 
Published: December 2024

As the transportation sector moves towards full electrification, the performance limitations of current Li-ion batteries, especially in demanding applications like electric vehicles, are prompting the development of advanced battery technologies. However, battery advancements are frequently pursued with an emphasis only on performance metrics, thereby relegating safety evaluation to the later stages of development. This approach is risky due to the disparity in safety characteristics between small and large-format cells.
This work aims to bridge the gap in the understanding of safety characteristics between small and large-format cells through a methodological approach that couples characterization, targeted experiments, and predictive modeling. Critical safety metrics are defined through detailed characterization and experimentation of materials and small-format cells. These metrics are then incorporated into sophisticated predictive models designed to anticipate the safety behaviors of large-format cells. This presentation will discuss our strategy for leveraging small-scale experimental results to forecast the safety profile of large-format cells, thereby informing safer and more effective battery technology development.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. SAND2024-04747A
Dependence of Lattice Constant and Oxygen Deficiency of CrNbO4 on Oxygen Partial Pressure
Authors: Kuo Yen-Ling , Fujita Shusei , Hayashi Shigenari , Nanko Makoto 
Published: December 2024

Because of the excellent oxidation resistance and superior mechanical properties at high-temperature environment, Ni-based alloy, 718 (Ni-19Fe-19Cr-5Nb-0.6Al-1Ti-3Mo) is one of the most used materials for gas turbines and related aerospace applications. Regarding to the oxidation performance of Alloy718, even though the chromium content 19 mass% is not sufficient to form a protective Cr2O3 scale on Ni-Fe-Cr alloys, the Alloy718 has excellent oxidation resistance by formation of an exclusive Cr2O3 scale. Based on our previous studies, the Nb addition to a Ni–19Fe–19Cr alloy could develop a continuous CrNbO4 layer at the metal-oxide interface, which acts as a diffusion barrier for inward oxygen and outward Fe and Ni diffusion and is favorable for rapid establishment of an external Cr2O3 scale. However, the interpretation in theprevious works is limited to insufficient information of defect chemistry in CrNbO4 oxides. To our knowledge, and the motivation for this study is that the defect chemistry of rutile CrNbO4 oxides has barely been studied to describe the composition versus oxygen partial pressure phase diagrams in this system. Therefore, the dependence of lattice constants and oxygen deficiency of CrNbO4 on oxygen partial pressure were investigated in the current study.
The CrNbO4 compounds used in this study were prepared by a solid-state reaction method. The initial materials of Cr2O3 and Nb2O5 had at least a purity of 99.9%. Oxygen partial pressure was varied during the heat treatment at 1000oC, the following buffers: Ni/NiO (P
O2 ≒10-11 atm), Co/CoO (P
O2 ≒10-12 atm), Fe/FeO (P
O2 ≒10-15 atm), H2/H2O (P
O2 ≒10-17 atm), Mn/MnO (P
O2 ≒10-24 atm) were used for yielding different levels of oxygen deficiency in the CrNbO4.

At relatively higher oxygen partial pressure, a small quantity of oxygen vacancies (≒0.01) created under Ni/NiO (P
O2 ≒10-11 atm) at 1000oC. Based on the results, maximum 0.05 per formula unit of vacancies could be created. However, a partial formation of Cr2O3 was found when reduced CrNbO4 samples were tried to be obtained below the partial pressure of Fe/FeO (P
O2 ≒10-15 atm) at 1000oC (Fig. 2). This could be attributed to the valence states from Nb5+ to Nb4+, forming a solid-solution of NbO2-CrNbO4 under relatively lower partial pressure at 1000oC. Based on experimental data, an increase NbO2 dissolution in NbO2-CrNbO4 solid-solution, that is, (Nb,Cr)O2, leading to the Cr2O3 precipitation under Mn/MnO (P
O2 ≒10-24 atm) at 1000oC. The present results show that CrNbO4 may initially formed and changed into (Nb,Cr)O2
solid-solution with increasing oxidation time. (Nb,Cr)O2
could coexist with Cr2O3 under low oxygen partial pressure at 1000oC.
A Physical Approach to Practical Applications of Lithium Metal Anode Using High-Flatness Cu Mesh Inducing Epitaxial Li Plating for All Solid-State Battery
Authors: Park Jihan , Park Minjoon 
Published: December 2024

Lithium metal batteries (LMBs) have been highlighted as next-generation energy storage systems due to their high energy density. However, dead Li and dendritic Li, induced by the large volume change of Li and inhomogeneous Li+ flux during Li plating/stripping, hinder the practical application of the LMBs. Especially, the copper foil, which serves as a two-dimensional substrate, increases the local current density and forms sharp Li nuclei due to its poor lithiophilicity. Furthermore, spatially varying surface kinetics induce repetitive volume expansion, resulting in the rupture of the solid electrolyte interface and reduced battery cycle stability. Therefore, numerous papers introduced 3D hosts (mesh, foam, gauze, and coil) to induce the dense Li deposition via reducing the local current density. In addition, the mechanically stable and spacious structure of 3D hosts easily accommodates the internal stress fluctuation and homogenizes spatially varying surface kinetics. Although these strategies effectively increase the safety and lifespan of LMBs, they are still impractical due to the large thickness and the long manufacturing time of the 3D-hosted lithium metal anode (LMA).
Herein, we report a facile physical approach to the fast fabrication of thin and lightweight 3D LMAs with ultralong cycle stability. The pressed Cu mesh (PCM) using a simple roll-pressing process could be fabricated speed of 0.2 m2 min−
1 and easy to scale up. In particular, the shape of the Cu wire had been modified from round to flat to enhance the lithiophicity. Therefore, the PCM uniformly coated with molten lithium (PCM-Li) achieved a thickness of 38 μm and a light weight of 11.9 mg cm−2. In symmetrical cell evaluation under 1mAh cm−
2@1mA cm−
2, the PCM-Li showed an ultrastable overpotential of 9.6 mV over 1,000 cycles. Furthermore, the PCM-Li maintained stable voltage behavior for more than 600 h even under 5mAh cm−2@5mA cm−2. Interestingly, in the SEM image of the PCM-Li after 1,000 cycles, no mossy or dendritic Li was observed, as Li was epitaxially plated along the flat Cu wires. Finally, we assembled a 1-Ah-scale high-energy LMB (351 Wh kg−
1) with the PCM-Li anodes and dry-coated NCM811 cathodes to demonstrate practical application. The LMB using the PCM-Li represented excellent practicality showing capacity retention of 80% during 200 cycles. This facile physical approach is helpful to the commercialization of next-generation lithium-based batteries and broadens the scope for subsequent research, such as lithiophilic materials coating for anode-free batteries.

Figure 1
Chemical Insertion of Li+ Enables Reversible, Anionic Redox in FeS2
Authors: DeBlock Ryan H. , Long Jeffrey W. , Ford Hunter O. , Bazargan Gloria , Chaloux Brian , Rolison Debra R. , Tighe Meghanne 
Published: December 2024

Lithium-rich transition-metal chalcogenides such as Li2FeS2 exhibit reversible charge-storage reactions via anionic sites (e.g., O2–, S2–, or Se2–), supplementing well-established metal cation-sited redox reactions to increase the energy density of lithium-ion batteries by up to 100 percent.1 Despite these promising characteristics, the structure–property relationships that govern cation- and anion-coupled redox reactions in chalcogenides remain poorly understood. To date the synthesis of such compounds has also been limited to high-temperature, solid-state methods that generate difficult-to-process, large-particulate solids. As an alternative, we describe a redox-mediated, wet-chemical strategy to insert Li+ into pyrite FeS2 to ultimately form Li2FeS2. With this method, the pyrite precursor may be formed from a number of methods to achieve greater control over particle size and allows for facile elemental substitution of Fe or S sites prior to chemical lithiation. The electrochemical characteristics (cation/anion redox potential, Li+-insertion capacity, reversibility) of the resulting lithiated iron chalcogenides are correlated with their electronic and structural properties as derived by X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and Raman scattering. We compare experimental results to density functional theory (DFT) calculations of analogous model compounds. Deconvolving the relationship between electronic band structure and reversible Li+ charge-storage will inform the design of future alkali-rich chalcogenides that exploit simultaneous cation + anionic redox.
1. C.J. Hansen, J.J. Zak, A.J. Martinolich, N.H. Bashian, F. Kaboudvand, A. Van der Ven, B.C. Melot, J.N. Welker, and K.A. See, J. Am. Chem. Soc. 142 (2020) 6737–6749.
Unravelling the Mechanism of Filiform Corrosion on Painted Carbon Steel
Authors: Fedel Michele , Rossi Stefano , Benedetti Luca , Deflorian Flavio , Cristoforetti Andrea 
Published: December 2024

Filiform corrosion (FFC) is recognized as a special case of an oxygen-concentration cell that forms on a metal beneath a paint layer, exhibiting a distinctive thread-like appearance. Under the paint, it is possible to distinguish the leading head from the growing tail thanks to the marked colour gradient. In fact, the front part of the head appears green coloured (in correspondence of the so called “green rust”) and tail brown coloured (in correspondence of the corrosion product containing Fe2O3, FeOOH, Fe (OH)3). FFC occurs on low carbon steel more frequently than expected, requiring only a relative humidity between 65% - 95% and mild chloride contamination to be triggered.
This study introduces a novel methodology for investigating the mechanism of filiform corrosion in organic coated steel. The approach leverages the scanning vibrating electrode technique (SVET) and potentiometric scanning electrochemical microscope (SECM), also known as micropotentiometry. By creating artificial defects in specific locations of the filaments under the coating, the electrochemical activity beneath the coating is evaluated by mapping ionic current densities. In addition, antimony tips are utilized to probe the metal-paint interface, enabling the assessment of local pH changes associated with various corrosion reactions.
Through in-situ measurements of electrochemical activity governing FFC on organic coated steel, this study precisely identifies the anodic and cathodic regions and determines the pH values at the metal-paint interface along the filament. Consequently, a more comprehensive depiction of the FFC mechanism emerges, addressing gaps in existing literature and validating hypotheses proposed over decades of research. Beyond insights into FFC, this investigation serves as a pioneering application of established techniques to explore corrosion mechanisms in coated metals.
(Digital Presentation) Experimental Analysis of Pit Initiation at MnS Inclusion in Low-Alloy Steel Using in-Situ Raman Spectroscopy
Authors: Fuji Hiroyuki , Imaki Ryota , Muto Izumi 
Published: December 2024

Low-alloy steel is an indispensable material for industry and infrastructure and is widely used in many fields because it can save cost and elemental resources. However, one of the disadvantages of low-alloy steel is its limited corrosion resistance compared to that of high alloys. Specifically, a major weakness is its high susceptibility to pitting in an environment containing Cl- ions. MnS inclusions are well known as preferential pitting sites because of its poor stability against chemical dissolution and ease of deformation by rolling. A lot of studies have investigated the mechanisms of pit initiation at MnS so far. Some detail analyses revealed that S species such as S2O3
2-, HS- and elemental S were generated due to dissolution of MnS, and they were harmful to pit initiation and active dissolution. However, these studies did not focus on ‘when’ those S species were generated. In addition, most of these previous studies focused on pitting in high alloys such as stainless steel and Ni-based alloy, so the mechanism of pit initiation in low-alloy steel is not yet fully understood.
This study aims to clarify the chronology between MnS dissolution, S species generation and pit initiation in low-alloy steel. The microscopic potentiodynamic polarization test was carried out in 20 mM NaCl added boric-borate buffer solution at pH 8.0. To analysis S species dissolved from MnS inclusions during the electrochemical test, in-situ observation using an optical microscope with high magnification and Raman spectroscopy were employed.
The polarization curve started at cathodic region, and then the corrosion potential was observed. In the anodic region, active dissolution and passive regions appeared in the curve as the potential increased. Finally, surges in the current density, attributed to pit initiation, was observed. In-situ observation ascertained that pit initiated at MnS inclusion whose longer diameter was 20 µm. Interval analysis of Raman spectroscopy during the test detected elemental S about 0.1 V below the pitting potential.
Analysis of the test solution after the polarization test also detected elemental S, although other S species such as S2O3
2- and HS- were not detected.
To confirm the morphology of the pit, cross-sectional observation was carried out using FIB/SEM. The pit was found to grow hemispherically, and corrosion product composed by Fe, Mn, O, and S was formed on the inner wall of the pit.
This study clarified that, MnS started to dissolve 0.1 V below the pitting potential. Then, elemental S was formed and concentrated in the vicinity of MnS inclusion. After elemental S concentrated enough to accelerate pit initiation, the active dissolution at the interface between MnS inclusion and steel matrix occurs rapidly to form pit. A part of elemental S deposited on the inner surface of the pit and form oxysulfide of Fe and Mn as corrosion product.
New Insights into the Electrochemical Reactions of Fluoride Ions in Carbon-Based Positive Electrodes
Authors: Ito Yuta , Lee Changhee , Miyahara Yuto , Miyazaki Kohei , Abe Takeshi 
Published: December 2024

The reversible and electrochemical reactions for the formation of graphite intercalation compounds (GICs) are fundamental to their use as electrode reactions in rechargeable batteries. A common practical application is the electrochemical intercalation and de-intercalation of Li+ ions within graphite electrodes of lithium-ion batteries (LIBs). Similarly, dual-graphite batteries (DGBs) employ GIC formation reactions and operate through the intercalation and de-intercalation of both cations and anions at the negative and positive electrodes, respectively, during charging/discharging processes. DGBs are gaining recognition as a viable alternative to LIBs because of their affordability, high operational potentials, reduced resource constraints, and environmental benefits.
This study presents the first observation of the electrochemical formation of F-GICs within LiF-containing organic liquid electrolytes. Despite attempts spanning nearly a century, the reversible intercalation of fluoride ions (F−) and their direct detection in electrochemical systems have remained elusive. Fluoride ions, known for their small ionic radius and high electronegativity, are theorized to provide high specific capacity and reaction potential, potentially leading to high energy densities in rechargeable batteries if they can be reversibly intercalated into graphite electrodes. Our findings were substantiated through operando Raman spectroscopy, which revealed changes in the G band peaks (i.e., in-plane mode of sp2 bonded carbon with a planar configuration) in highly oriented pyrolytic graphite (HOPG) during electrochemical oxidation. This indicates the formation of F-GICs. Moreover, the introduction of a LiF-based surface layer on the HOPG electrodes significantly improved the kinetics and reversibility of the electrochemical intercalation and de-intercalation processes of F−.
Consequently, based on these results, the present study suggests that the electrochemical formation of F-GICs can occur in organic electrolytes without the need for additional acceptors or additives. Furthermore, this study provides insights into the operando Raman spectra for the electrochemical formation of F-GICs, elucidating the mechanisms of the electrochemical F− reactions in HOPG electrodes. Moreover, enhancing the contact between LiF and the graphite surface can significantly accelerate the rate of F− intercalation, offering a new perspective on the design of graphite positive electrodes for rechargeable batteries.

Figure 1
Microstructural Analysis of Lithium-Ion Battery Cathodes Toward Improved Manufacturing Sustainability
Authors: Brenneis Willa , Liu Qingsong , Richards Jeffrey J. , Lopez Jeffrey 
Published: December 2024

Improvement of lithium-ion battery (LIB) energy density is necessary to increase adoption of electric vehicles (EVs) and curb transportation emissions. Within the LIB, the cathode structure controls the flow of ions and electrons, and thus is a major driver of battery performance.1 Intentional design of LIB cathodes for facile ionic transport will enable rapid charging of thick cathodes for increased cell energy density. Here, we have the opportunity to prioritize sustainability by reimagining traditional cathode manufacturing processes in tandem with advancing understanding of cathode microstructure. To this end, we leverage insight gained by the careful study of slurry-cast cathode carbon-binder domain (CBD) structure to facilitate the transition to solvent-free cathode fabrication, which promises a significant reduction in the use of toxic solvents, energy, and capital in the manufacturing process.2

In this talk, I will first discuss relationships we have uncovered between slurry-cast CBD nanostructure and cathode performance. The use of small-angle neutron scattering (SANS) with solvent contrast variation in combination with electrochemical impedance spectroscopy (EIS) and plasma focused ion beam scanning electron microscopy (PFIB-SEM) allows us to analyze cathodes in both wet and dry states, at the nanoscale, and across representative volumes. Using SANS, we identified the expansion of CBD agglomerates upon addition of an electrolyte solvent and after calendaring. Further, we determined separate binder and carbon surface areas, allowing us to correlate a decline in cathode cycling performance to increased electrolyte-accessible carbon black surface area. Together, these findings inform the design of the CBD for improved cycling stability.
We now utilize our understanding of slurry-cast CBD to improve the design of dry-processed electrodes. The dry CBD microstructure is distinct from and even less understood than that of slurry-cast electrodes, though facile ionic and electronic transport remain crucial. We employ the tools presented here to explore the microstructure of dry electrodes fabricated via the formation of binder fibers under applied shear. Binder fibers create a uniform and stable CBD matrix to support the active material, which allows us to reduce the fraction of binder and expand the cathode thickness, increasing cell energy density. Our study of both dry-processed and slurry-cast cathodes advances fundamental understanding of ionic and electronic transport mechanisms in diverse microstructures and across manufacturing processes, while the transition to dry-processed electrodes reduces cost and environmental impact.
References:

Entwistle, J. et al.
Renew. Sustain. Energy Rev.
166, 112624 (2022).

Lu, Y. et al.
Matter
5, 876–898 (2022).