bluuebunny/crossref_metadata_2025 huggingface dataset:
Effective Conductive Networks from Carbon Materials for Lithium-Ion Batteries
Authors: Baumgartner Julian F. , Kravchyk Kostiantyn V. , Kovalenko Maksym V.
Published: December 2024

Conductive networks are integral components in Li-ion battery electrodes, serving the dual function to provide electrons to the active material while its porosity ensures Li-ion electrolyte accessibility to deliver and release Li-ions, thereby ultimately determining the electrochemical performance, regardless of the active material. In the realm of academic research, the task of fabricating an electrode equipped with an effective conductive network emerges as a daunting challenge, profoundly influencing a researcher's ability to showcase the intrinsic electrochemical performance of an emerging active material. Amidst the plethora of conductive additives available for battery electrodes, researchers often find themselves navigating a labyrinth of choices, grappling with decisions on a suitable additive and the optimal methodology for electrode preparation.

This review talk seeks to provide fundamental understanding and practical guidelines for designing battery electrodes with effective conductive networks across various length scales.[1] This involves meticulous selection of specific carbon conductive additives from the plethora of options, and exploring effective integration methods into the electrode, all tailored to the unique characteristics of the active materials and the specific research objectives.

[1] J. F. Baumgärtner, K. V. Kravchyk, M. V. Kovalenko, Adv.
Energy Mater.
2024, Manuscript Accepted.

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(Invited) Tackling Leakage, Drift, and Variation in Printed Carbon Nanotube-Based Electronic Biosensors
Authors: Franklin Aaron D
Published: December 2024

Semiconducting carbon nanotubes (CNTs) have been pursued for use in electronic biosensors for decades. Their all-surface molecular structure, sizeable semiconducting bandgap, and solution-phase compatibility make them highly sensitive and versatile options for transducing biomarker-related electrical signals. However, amid the thousands of reports on CNT-based electronic biosensors, very little attention has been given to identifying (let alone addressing) the impact of leakage current, signal drift, and device-to-device variation, particularly under operation in biologically relevant ionic media. This talk will present recent results focused on tackling these issues in a CNT transistor-based biosensor platform (i.e., bioFETs or ion-sensitive FETs). For instance, a variety of passivation strategies were studied to determine the role of leakage current compared to the detection signal, revealing that a bilayer epoxy/high-k dielectric stack was most effective at minimizing deleterious leakage. The influence of signal drift, particularly in strong ionic solutions (e.g., 1X PBS), was also found to play a significant role in many previous reports of CNT-based biosensors that were characterized by sequential biomarker concentration spikes. Finally, strategies for addressing device-to-device variation in these biosensors will be discussed, including the motivation for a printed thin-film device rather than a single-CNT configuration. Two things seem certain about this field: 1) the promise of CNT-based biosensors continues to suggest they are worth ongoing pursuit, and 2) there is much work remaining towards achieving a reproducible, reliable electronic biosensing technology from CNTs.
(Digital Presentation) Effect of Multimode Microwave on Ni@C Synthesized By Polygonal Barrel Plasma CVD
Authors: Kodera Fumihiro , Sato Nobukazu , Ohara Sota , Inoue Mitsuhiro , Miyakoshi Akihiko , Umeda Minoru , Abe Takayuki
Published: December 2024

Metal-encapsulated carbon (M@C) microparticles are known to exhibit unique electrode performance due to their geometric structure. Recently, we succeeded in simultaneously synthesizing turquoise hydrogen and Ni@C microparticles by catalytic methane decomposition using multimode microwaves. For theoretical support of electrode reactions at this Ni@C microparticles, model compounds are indispensable. However, it is generally difficult to obtain modeled M@C microparticles. In this study, we attempted to synthesize Ni@C microparticles using polygonal barrel plasma CVD. Furthermore, the effects of multimode microwaves on the synthesized Ni@C were evaluated using Raman spectroscopy and electrochemical measurements.
Single-Membrane pH-Decoupling Aqueous Battery Using Proton-Coupled Electrochemistry for pH Recovery
Authors: Xi Dawei , Yang Zheng , Alfaraidi Abdulrahman , Aziz Michael J.
Published: December 2024

Aqueous redox flow batteries (ARFBs) constitute a promising technology for cost-effective and scalable storage of intermittent renewable energy from sources like wind and solar. For long discharge-duration storage (> 8 h), these batteries offer a unique advantage by decoupling energy storage from power generation, providing a level of design versatility and scalability that traditional rechargeable batteries can hardly match. Typically, the negolyte and posolyte of ARFBs exhibiting long-term operation have roughly the same pH. In contrast, pH-decoupling aqueous redox flow batteries (ARFBs) utilize different pH values in the negolyte and the posolyte, enabling the cell to achieve higher cell voltages and support a broader range of redox pair combinations. Managing the crossover of acid and base, along with an economical and straightforward method to recover their crossover, is critical for long-term operation of pH-decoupling ARFBs. We have previously investigated the crossover of acid and base in multichamber pH-decoupling ARFBs and developed a small, but adequately-sized bipolar membrane (BPM) sub-cell for pH recovery.1 Here, we introduce a new pH-decoupling design utilizing a conventional single-membrane ARFB architecture. This approach reduces the ohmic area-specific resistance while maintaining an acceptably low level of acid-base crossover. We explore various electrolyte pairs, ranging from solutions to semi-solids, anions to cations, acids to bases, showing that this design allows flexibility in electrolyte combinations. The setup can result in improved energy efficiency, higher areal power density, and reduced capital costs. Along with different cells, we demonstrated how proton-coupled electrochemical reactions can serve as proton pumps, enabling in-situ or ex-situ pH recovery in these pH-decoupling setups and discussed its relationship to BPM pH recovery.

1. Xi, D., Alfaraidi, A.M., Gao, J. et al. Mild pH-decoupling aqueous flow battery with practical pH recovery. Nat Energy (2024). https://doi.org/10.1038/s41560-024-01474-1

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Deciphering the Potential Shifts in Highly Concentrated Litfsi Aqueous Electrolyte
Authors: Kang Junsik , Lee Hochun
Published: December 2024

This study unravels the potential shifts in LiTFSI aqueous solutions, including Li-salt activity effect and liquid junction potential, by characterizing concentration-dependent cation transference numbers (t
+) and thermodynamic factors (θ). In the 0.5–5 M concentration range, t
+ decreases from 0.6 to 0.3, while θ increases from 1.2 to 12.2. The concentration-dependent correlations of t
+ and θ yields +32 mV of ∆E
j between the 5 M test solution and 1 M reference solution and a 103-fold increase in salt activity, corresponding to a ~180 mV upward shift in Li-ion (de)-intercalation potential. Lastly, the cyclic voltammetry of Fe(CN)6
3−/4− in LiTFSI solutions, corrected by ∆E
j, revealed that the increasing Li-ion reactivity upward shifts the redox potential of Fe(CN)6
3−/4− upon increasing LiTFSI concentration, evidenced by solution polarity measurement. This work offers a systematic solution for the potential shift and insights into the highly concentrated electrolytes.

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Probing the Process of Electron Transfer in Microemulsions with Substituted Ferrocenes
Authors: Arif Muhammad Zulqarnain , Imel Adam E. , Barth Brian , Zawodzinski Thomas A.
Published: December 2024

Recently, we reported studies in which microemulsion-based electrolytes were used in redox flow batteries. That work built on studies of the electrochemistry of ferrocene in toluene/water/TWEEN® 20 microemulsions which showed the electron transfer to be remarkably facile, with reversible or quasi-reversible kinetics observed in cyclic voltammetry experiments with scan rates up ~20 V/sec. To rationalize these high rates, we speculated that the oxidation of ferrocene to ferricenium ion was accompanied by rather subtle changes in the ‘space charge’ region associated with ions in the aqueous sub-phase/hydrophilic interphase. (TWEEN® is a. non-ionic surfactant with multiple ethylene oxide oligomers as its head group.). However, it is also possible that the ferricenium ion is ejected into the aqueous phase. The latter process could lead to instability during cycling of the battery. To probe this question, we are exploring the electrochemistry and other associated dynamic processes in toluene/water/TWEEN® 20 microemulsions that contain various substituted ferrocene derivatives as electroactive components. Compounds were chosen using estimates of dipole moments from quantum mechanical calculations to provide an initial screen of polarity. Modifications ranging from mono- and di-carboxylic acid derivatives and a series of esters synthesized from the acids, to tertiary amines and to decamethyl ferrocene were probed. An overview of the outcomes of these studies will be presented, together with a discussion of implications for microemulsion ‘design’ to co-optimize electron transfer rate and cycling stability of the system when used batteries.
Microemulsion-Solubilized Menadione As a Redox Flow Battery Negolyte: Electrochemical Surface-Enhanced Raman Spectroscopy Insights
Authors: Sharma Bhavya , Barth Brian , Zawodzinski Thomas A.
Published: December 2024

Understanding the electron transfer processes of quinone electrolytes is pivotal for advancing organic redox flow batteries (RFBs) and optimizing their performance. In this study, we employed electrochemical surface enhanced Raman spectroscopy (EC-SERS) to investigate the electron transfer mechanism of microemulsion (μE) - solubilized menadione, a quinone based vitamin. Combining electrochemistry and SERS offers sub-second time and high spatial resolutions, with excellent sensitivity and selectivity. Recently menadione was used in a μE RFB, where electrochemical reversibility was demonstrated to be µE dependent. The electron transfer mechanisms for menadione solubilized in a μE has yet to be reported. By coupling ultramicroelectrode techniques with SERS we investigate the redox behavior of menadione within the context of redox flow batteries.

Our research centered on the elucidating the proton coupled electron transfer pathways for menadione in μEs. The reaction mechanism for a quinone is strongly dependent on the protic nature of the solvent. μEs have the unique property of combining both aqueous and non-aqueous phases at a nanometer scale in a single stable solution. We examine the effects of aqueous phase pH and oil phase hydrogen-bond donor strength on the electrochemical mechanism for a quinone confined to the oil phase. We also address the role of μE morphology on the possible mechanism. We speculate the role of μE ordering on long-term quinone stability. Ultimately, knowledge of the mechanism will provide insight into kinetics and thermodynamic parameters which determine RFB performance.
Revisiting Microemulsion Electrochemistry
Authors: Barth Brian , Imel Adam , Zawodzinski Thomas A.
Published: December 2024

We present a study of electron transfer kinetics in microemulsion (µE) electrolytes and address possible mechanisms. This work is motivated by our exploration of µEs as redox flow battery (RFB) electrolytes. Our previous studies characterize µEs using small angle neutron scattering, pulsed-field gradient nuclear magnetic resonance spectroscopy, conductivity measurements, and phase behavior diagrams. Results from these studies on ferrocene and menadione redox probes demonstrated surprisingly facile kinetics in bicontinuous sodium dodecyl sulfate µEs at a planar glassy carbon electrode. While preliminary screening with cyclic voltammetry identified these systems as possible RFB electrolyte candidates, electrochemical reversibility was strongly dependent on µE composition. This draws attention to the role of µE properties such as bulk and near-surface ordering, interfacial packing, and dynamics on electron transfer. Ultimately, the realization of µE RFBs requires a fundamental understanding of µE electrochemistry including kinetics and the underlying mechanisms, which are currently unclear.

In this talk, we re-evaluate µE electrochemistry. Historical interpretations often assumed identical bulk and near-surface ordering and a constant electrochemical surface area, independent of µE composition and electrode properties. We address limitations of these assumptions. Furthermore, we compare more recently suggested electron transfer mechanisms in emulsions to µEs. We probe the impact of domain size on the potential mechanism from the perspective of the electroneutrality approximation, including the effects of µE composition, morphology, and interfacial fluidity. In addition, both oil- and water-soluble, and inner- and outer-sphere redox probes are utilized with the aim of understanding the role of the structured µE solvent in the electron transfer process. We leverage insights from these fundamental studies and suggest possible implications for improving the current state of µE RFBs.
Parametric Analysis of Aluminum-Air Batteries with Focus on Aluminum Product Layer Management for Enhanced Power Output
Authors: Griffith Colt , Washington Brian , Goenaga Gabriel , Foister Shane , Zawodzinski Thomas A.
Published: December 2024

Aluminum-air batteries are a promising next-generation technology due to their high energy density coupled with the abundance of aluminum and a well-established supply chain. One field that stands to particularly benefit from these greater capacities is aircraft electrification. Aviation applications pose a unique challenge in that the energy source for flight must provide a considerable upside relative to the weight it adds to the vehicle. Lithium-ion technology has been successfully implemented in drones for short flight times, but aluminum-air batteries have the potential to greatly extend the durations of these flights. While the energy density is where this chemistry has a unique competitive advantage, the power output presents a challenge. Although researchers have investigated lithium-ion battery discharge at high C-rates, most aluminum-air battery research has focused on maximizing utilization and energy density. For viable implementation in electric aircraft, focus must be placed on maximizing the power output of the aluminum-air chemistry with care to maintain the energy density that gives it its competitive advantage. At high power outputs, system performance is largely dictated by ohmic losses on the anode side associated with the aluminum product layer. Turnover of this secondary passivation layer is based on conversion of insoluble aluminum hydroxide to soluble aluminate ions, and this can be strongly influenced by several system parameters including electrolyte concentration, temperature, and flow rate. This investigation conducts a parametric analysis of these parameters with respect to their influence on resistance of the aluminum product film and its dissolution. The effects will primarily be studied using electrochemical impedance spectroscopy and polarization curves in conjunction with insight from Tafel analysis, surface imaging, and extended discharge testing. Both three-electrode and full-cell setups will be used for testing to allow for clear insight to surface-level processes and an idea of how the investigated factors scale up when implemented in a real system. Management of the aluminum product film is critical for achieving high power output, and this investigation will provide further insight to how key cell parameters influence the realization of this goal.
(Invited) Development of All Solid-State Batteries with Sulfide Solid Electrolytes: From Materials to Characterizations
Authors: Kim Jung-Hyun
Published: December 2024

Sulfide-based solid electrolytes (SEs), such as lithium (Li) - argyrodites (e.g., Li6PS5X, where X = Cl, Br, I), have attracted significant attention among various inorganic materials due to their high ionic conductivity (> 10-3 S/cm) and manufacturability of all solid-state batteries (SSBs). However, the practical application of these materials is still challenging due to several technical issues, including problems with the electrode-electrolyte interphase and Li-dendrite growth, which compromise the safety and lifespan of SSBs. In this presentation, I will highlight our recent efforts to (i) identify the failure modes of sulfide-based SSBs and (ii) propose viable solutions to address these challenges.

To begin, I will illustrate the dynamics of lithium-dendrite growth through liquid electrolytes in conventional lithium-ion batteries compared to solid electrolytes in SSBs. I will explore and highlight both the similarities and differences in the behaviors of lithium-dendrite growth across these systems.

Electrochemical methods are routinely employed to assess the performance and failure modes of SSBs. A key technique in R&D is the critical current density (CCD) technique, which evaluates the dynamic stability of the lithium/solid electrolyte (Li/SE) interface by incrementally increasing the current density until the interface/bulk fails. However, we found that the effectiveness of this technique is heavily influenced by three factors: (i) cell design, (ii) cell materials, and (iii) electrochemical measurement protocols. The impact of each factor on CCD values and the methods proposed to achieve reproducible CCD measurements will be discussed in detail. In addition, the distribution of relaxation times (DRT) technique serves as a powerful tool for identifying failure modes in SSB cells. I will present representative DRT behaviors observed in SSB cells, identifying the underlying degradation processes that contribute to cell failure.

Finally, I will discuss our recent efforts to enhance the stability of interfaces, thereby improving the performance of SSBs. One approach involves improving the properties of lithium-argyrodite SE by tuning their chemical compositions.
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).
An Aqueous Redox Flow Battery Using CO2 as an Active Material
Authors: Kanega Ryoichi , Yamamoto Akira , Yoshida Hisao , Sato Yukari , Ohira Akihiro
Published: December 2024

H2 storage system utilizing the interconversion of CO2 and formate, named a chemical hydrogen battery, has been proposed. The system stores H2 via CO2 hydrogenation to produce formic acid (or formate) and releases H2 via formic acid (or formate) dehydrogenation. Beller et al. reported a catalytic system combining lysine with Mn based homogeneous catalysts and pincer ligands to achieve 10 charging-discharging cycles1. In the H2 release step, lysine acted as a base and trapped CO2, generating >99% pure H2. In addition, our research group developed Ir-based homogeneous catalysts that could drive a chemical hydrogen battery2. The Ir-based homogeneous catalyst enabled H2 storage under ambient conditions and produced 1 MPa of H2 in the H2 release step. However, in the chemical hydrogen battery, energy losses are inevitable in the conversion of electrical energy to H2 as chemical energy and H2 to electrical energy, resulting in a loss of more than half of the input electricity.

Thus, we considered that the significant energy loss could be overcome by directly storing and generating electrical energy without using H2. In this presentation, we introduce an aqueous redox flow battery in which the anolyte involves a CO2–formate redox pair based on homogeneous Ir catalysts, while the catholyte involves an MnII–MnIII redox pair. The system exhibited a maximum discharge capacity of 10.5 mAh (1.5 AhL-1), capacity decay of 0.2% per cycle, and total turnover number of 2550 after 50 cycles3. In the redox flow battery system, the formation of IrIV and high-valence hydride species, in contrast to the case of the chemical hydrogen battery, worked as active species and was supported by the in situ fluorescence Ir L
III-edge XAFS spectroscopic analysis using the newly constructed online setup.

References

[1] D. Wei, R. Sang, P. Sponholz, H. Junge, M. Beller, Nat. Energy,
2022
7, 438-447.

[2] N. Onishi, M. Iguchi, X. Yang, R. Kanega, H. Kawanami, Q. Xu, Y. Himeda, Adv. Energy Mater.
2019, 9, 1801275.

[3] R. Kanega, E. Ishida, T. Sakai, N. Onishi, A. Yamamoto, H. Yasumura, H. Yoshida, H. Kawanami, Y. Himeda, Y. Sato, A. Ohira, Angew. Chem. Int. Ed.,
2023, 62, e202310976.

Figure 1
In-Situ Observations of Li+ and Na+ Storage in Anodic Nanotubes
Authors: Kowalski Damian , Vincent Mewin , Sajeev Sandra
Published: December 2024

Anodizing is a high-voltage electrochemical conversion process that forms barrier-type oxide layers or self-organized nanoporous/nanotubular structures. So far, the Al2O3-like nanopores and TiO2-like nanotubes could be successfully synthesized on many valve metals and alloys. Recently, it become possible to form nanotubular structures on iron and consequently control the ratio of hematite (Fe2O3) to magnetite (Fe3O4) by subsequent thermal treatment.1 Electrochemically active nanotubes, such as self-organized TiO2 are of high interest in the battery field due to a unique one-dimensional (1D) geometry offering high volume expansion tolerance and applications without binders and conductive additives. Herein, we report an in-situ Raman spectroscopy study under current control for a better fundamental understanding of Li+/Na+ storage in nanotubes and correlate the structural fingerprints with the electrochemical data on differential capacity plots of d(Q–Q
0) dE
–1.2 Real-time measurements revealed that the nanotubes had undergone two major phase transformations with increasing lithium content, disclosing the sequential steps of a lithium intercalation type of storage. In contrast, sodium-ion insertion induced no significant crystal structure modification but instead a slight crystallinity rupture, signifying a dominant nondiffusion-limited capacitive type of storage. The insight into the charge storage in a 1D material in relation to other nanostructures such as nanoparticles3 will be discussed.

References:

L. Fadillah, D. Kowalski, M. Vincent, C. Zhu, S. Kitano, Y. Aoki and H. Habazaki,
ACS Applied Materials & Interfaces
, 2023, 15, 52563-52570.

M. Vincent and D. Kowalski,
ACS Applied Nano Materials
, 2023, 6, 6528-6537.

M. Vincent, S. Sajeev and D. Kowalski,
Electrochimica Acta
, 2023, 469, 143161.

Figure 1. 3D in situ Raman spectroscopy patterns of Li-ion insertion to TiO2 nanotubular electrodes. The spectra were obtained under a GCPL protocol. Raman spectra were collected using a Thermo Scientific DXR3 Raman microscope fitted with a 532 nm laser equipped with an in-situ ECC-OPTO El-Cell.

Figure 1
(Invited) “Armor-Coated” Enzymes: Chemistry and Properties of Functional Biomolecules Trapped in Mesoporous Silicon Nanoparticle Cages
Authors: Sailor Michael J
Published: December 2024

This presentation will highlight chemistries that can be used to encapsulate enzymes within the confines of electrochemically prepared porous silicon-based nano-cages while retaining protein function. Because of the sensitive nature of proteins, the trapping chemistries must operate under mild aqueous conditions such that the mesopores can dynamically restructure to immobilize and confine the enzyme without inducing denaturation or hydrolytic decomposition. Three general approaches are compared: (1) oxidative trapping, where mild aqueous oxidation of the elemental silicon skeleton in the mesoporous silicon host swells and restructures the pore walls, physically trapping the payload in a porous SiO2 matrix; (2) hydrolytic trapping, where an already formed oxide hydrolyzes in response to stress and is induced to re-precipitate around the protein payload by non-covalent interactions; and (3) calcium ion-induced condensation, where localized precipitation of calcium silicate entraps the protein in a porous silicate matrix. The impact of each chemistry on stability and catalytic performance of the trapped enzyme will be compared.