Composition Of Layer Research Articles

Reduction and Oxidation Behavior of Rust Layers Under Aqueous Solution Films with Different Thicknesses

It is well known that steel materials widely used in infrastructures corrode rapidly in atmospheric environments. As a result of corrosion, rust layers form on steel surfaces exposed to repeated wet and dry environments. In such wet and dry environments, redox reactions of rust layer may occur and accelerates the corrosion of steels. Such redox behavior can strongly depend on the composition of rust layer and the thickness of the solution film that is present on the surface in the wet stage. In this study, we investigated the effect of solution film thickness on the redox behavior of two types of rust layers with different compositions, i.e. FeOOH-rich and Fe3O4-rich rust layers.Specimens used were carbon steels, on the surfaces of which either of rust layers was present, that is, FeOOH-rich or Fe3O4-rich rust layers. FeOOH-rich rust layers were produced though atmospheric exposure of carbon steel for 3 months. On the other hand, Fe3O4-rich rust layers were produced by dipping of FeOOH-rich rust layers in 0.1M Na2SO4 solution of pH 5 at 50 ℃ for 24 h. The specimens were subjected to the solution film test in which the rust layers were covered with 0.1M Na2SO4 solution film with various thicknesses. To avoid evaporation of the solution film, the specimens were put into tightly sealed container and kept in a thermostatic chamber at 50 ℃ for 24 h. After the test, the solution films on the specimen surfaces were removed and then dried at 60 ℃ and 50% R.H. for 6 h.X-ray diffraction pattern obtained for the specimens indicated that main rust constituents in each specimen were Fe3O4, α-FeOOH, and γ-FeOOH. The mass fraction of each rust constituent was calculated from the peak intensity of the X-ray diffraction and based on the calculation, the Fe2+/Fe3+ ratios in the rust layers were estimated. The Fe2+/Fe3+ ratio in the FeOOH-rich rust layer increased after the solution film test and the increase varied depending on the solution film thickness. In the thinner range than 200 µm, the increase of the Fe2+/Fe3+ after the test was relatively low whereas in the thicker range than 200 µm, the increase was significantly large, indicating that the reduction of FeOOH predominantly occurred under thick solution film. The Fe2+/Fe3+ ratio in the Fe3O4-rich rust layer tended to decrease with decreasing the solution film thickness. These imply that the reduction and oxidation of rust layers depend not only on the thickness of the solution film present above rust layer but also its composition.

Inorganic-Rich SEI Derived from Electrochemically Deposited [Cu(TU)n]Cl Nanowires for Highly Stable Lithium Metal Batteries

Li metal batteries (LMBs) are promising next-generation energy storage systems because of the low electrode potential (-3.04 V vs. S.H.E) and high capacity (3,860 mAh g-1) of lithium metal anodes (LMAs). However, LMAs suffer from unavoidable dendrites and huge volume expansion of lithium resulting from unstable solid electrolyte interface (SEI) which has poor ion conductivity and mechanical strength [1]. To address these issues, artificial SEI is one of the most efficient methods to enhance its stability and hence prolong the lifespan of LMAs by modifying the electrode surface with metal compounds like copper sulfides [2] and halides [3]. In particular, inorganic materials derived from the metal compounds such as Li2S, LiCl, and Li3N have been widely known as high-quality SEI components. Li2S and Li3N have high Young’s modulus of 82.6 [4] and 150 GPa [5] respectively. Also, LiCl (0.05 eV) have a lower Li-ion diffusion barrier compared with LiF (0.28 eV) [6]. However, the existing methods for coating metal compounds on substrates such as hydrothermal, CVD, and sputtering have drawbacks requiring high temperature and high vacuum systems. In this work, we introduce a facile electrochemical deposition method for fabricating [Cu(CH4N2S)n]Cl nanowires (CTC NWs) resulting in inorganic-rich SEI layers. The Cl- and thiourea (TU) in CTC NWs were converted to LiCl and Li2S respectively. Additionally, the residual TU catalyzes the formation of Li3N-rich SEI layer promoting decomposition of LiNO3 additive.The bare Cu and CTC NWs surfaces after 10th cycle were investigated by XPS to study the chemical composition of the inorganic SEI layers (Fig. 1). For the S 2p spectra (Fig. 1a, d), the peaks at 160.5 and 162.5 eV were assigned to Li2S and Li2S2, which have higher intensity in CTC NWs. Additionally, the presence of new peak at 161.9 eV indicates Li2Sx (Fig. 1a). these lithium sulfides in the CTC NWs were induced by decomposition of TU. The signals in S 2p spectra of sulfone, SO3- and SO2- were originated from the decomposition of lithium salts (LiTFSI) in the electrolyte, which were confirmed in the all samples (Fig. 1a, d). The Cl 2p XPS spectrum shows only a peak of LiCl (198.7 and 200.3 eV) in the CTC NWs (Fig. 1b). As shown in N 1s spectra (Fig. 1c, f), the peak at 397.5 eV is Li3N, indicating the decomposition of LiNO3 which could result in the formation of Li3N. Meanwhile, the observed signal of LixN and pyrrolic N (C-N-H) was only detected at 398.5 and 399.6 eV in the CTC NWs, resulting from the residual TU (Fig. 1c).The Nyquist plots were employed to compare the interfacial resistance change of the Li||Cu and Li||CTC NWs half-cell after a certain number of cycles (Fig. 2). After 60th cycle, the interfacial resistance of CTC NWs cell decreased much lower than the bare Cu cell, which demonstrate that inorganic-rich SEI layers derived from CTC NWs is more favorable to rapid charge transfer.To further investigate the effect of the CTC NWs, we evaluated the electrochemical performance of Li plating/stripping behavior. The Li||CTC NWs exhibits enhanced cyclability, demonstrating a higher average coulombic efficiency (CE) of 96.2% over 100 cycles compared to Li||Cu. (Fig. 3). Furthermore, a comprehensive analysis of the morphological and chemical attributes of the inorganic-rich SEI layers induced by CTC NWs will be discussed in this presentation.

(Invited) Epitaxial Growth and Development of Complimentary Field-Effect Transistors

The semiconductor industry is currently at a pivotal juncture, with major chip fabrication facilities having exhausted FINFET technology and now transitioning to a new device architecture of gate all around (GAA). The next architecture in this progression (beyond 1nm), crucial for scaling down is Complementary Field-Effect Transistors (cFETs). In cFETs, nMOS and pMOS are stacked on top of each other, eliminating the gap and resulting in significant reduction of area and maximization of channel width and drive current.[1-3] In this work, we present our research on epitaxial growth of cFET stacks and discuss our design strategies and the key evaluation metrics in accordance with the downstream processes. We delve deeper into the bottom-up growth of cFETs using Chemical Vapor Deposition (CVD) epitaxy and explore the impact of temperature, precursor gases, and Germanium content on the quality and strain engineering of cFETs. We exploit various characterization techniques to quantify defects, strain, uniformity, and composition of the epitaxial layers comprising the cFET stacks, followed by tuning of the process parameters accordingly to achieve a high-quality, fully-strained stack. Through this study, we aim to provide valuable insights into the growth and optimization of cFET structures, thereby facilitating their integration into future transistor nodes.[1] P. Schuddincket al., 2022 IEEE Symp. on VLSI Techn. & Circuits, Digest of Technical Papers, p. 365.[2] S. Subramanian et al., 2020 IEEE Symp. on VLSI Techn. & Circuits, Digest of Technical Papers, TH3.1.[3] A. Vandooren et al., 2022 IEEE Symp. on VLSI Techn. & Circuits, Digest of Technical Papers, p. 330.

Water Permeability and Oxygen Transport Resistance of Hydrophilic and Hydrophobic Composite Microporous Layer Coated Gas Diffusion Layer

Water management is vital to enhance the performance of polymer electrolyte fuel cells (PEFCs). Previously, a hydrophilic and hydrophobic composite microporous layer (MPL) coated gas diffusion layer (GDL) was developed to promote robustness to humidity. It was proved that the composite MPL containing hydrophilic and hydrophobic pores in the same layer was effective in reducing the oxygen transport resistance from measured limiting current density under conditions of the cell temperature of 35°C, supplied gas relative humidity of 200% and flow rate of 1000 cm3 min-1. However, directly distinguishing the hydrophobic and hydrophilic microporous structures in the composite MPL is difficult. In this study, we try to clarify the ratio of hydrophobicity and hydrophilicity contributed to liquid water distribution and oxygen transport resistance.The water permeability test across hydrophilic, hydrophobic, and composite MPLs established the relationship between water flow rates under varying pressure conditions. The water breakthrough pressure obtained with the composite MPL was similar to that obtained with hydrophilic MPL. The composite MPL demonstrated two different rising slopes of the water flow rate. The hydrophilic pores caused the initial slope, which followed the tendency of hydrophilic MPL because water could readily pass through the hydrophilic pores. The following slope changed when the water supply pressure was high enough to pass the hydrophobic pores, and the slope was close to the pure hydrophobic MPL. The water flow rate obtained with the composite MPL was much higher than that obtained with the hydrophobic MPL. Based on the water permeability characteristics, it is considered that the hydrophobic and hydrophilic pores were separately generated in the composite MPL.To further clarify the contribution of hydrophobicity and hydrophilicity ratio to water transport, liquid water flow rate values for MPLs were derived from Darcy's law to fit the water permeability test data under identical pressure. According to the fitting results, a composition comprising 4% hydrophilicity and 96% hydrophobicity was determined to yield results consistent with the water permeability test, in which the actual composite MPL possessed 10 mass% PVDF, 7.5 mass% Nafion, 2.5 mass% TiO2 and 80 mass% carbon black.Based on this ratio, the Leverett function was employed to assess the distribution of liquid water saturation within hydrophobic, hydrophilic, and composite MPLs. In the composite MPL, liquid water saturation reached higher levels from the substrate to the hydrophilic pores in the MPL and almost remained constant from the MPL to the MPL/catalyst layer (CL) interface, indicating that the hydrophilic pores were utilized as water transport pathways. Conversely, hydrophobic pores in the MPL were not fully saturated, leaving most pores empty for gas transport. This balanced configuration of hydrophilicity and hydrophobicity substantially reduced the oxygen transport resistance. An additional assessment of the properties ratio was conducted, assuming that the cell operating current density was 3 A cm-2 and the water flow generated in the reaction was obtained. Under the same water flow rate conditions, increasing the hydrophilicity ratio from 0% to 4% resulted in decreased oxygen transport resistance, attributed to a reduction in water breakthrough pressure at the interface between the MPL and CL, facilitated the expelling of liquid water at the MPL/CL interface more effectively compared with a conventional hydrophobic MPL. However, further elevating the hydrophilicity ratio from 4% to 30% resulted in lower water breakthrough pressure but higher water saturation within the MPL. The saturated MPL possessed fewer pathways for gas transport, raising the oxygen transport resistance. Therefore, the inappropriate hydrophilicity and hydrophobicity ratio disrupted the optimal water-gas equilibrium, causing increased oxygen transport resistance. Through a comparative analysis of experimental and calculated data, the optimal formulation emerges, comprising 10 mass% PVDF, 7.5 mass% Nafion, 2.5 mass% TiO2, and 80 mass% carbon black, delineating hydrophilicity and hydrophobicity ratios of 4% and 96%, respectively.

Electrochemical Performance of LiNi0.5Mn0.5O2 Electrode in All-Solid-State Battery

IntroductionOxide-based all-solid-state batteries (Ox-ASSBs) have been attracting attention as next-generation secondary batteries because of their high safety and high energy density. Recently, Ox-ASSBs have been reported by use of LISICON-type Li3.5Ge0.5V0.5O4(LGVO) as a solid electrolyte and layered NaCl-type LiCoO2 and LiNi1/3Mn1/3Co1/3O2 as positive electrodes. We have focused on Li2MnO3-based positive electrodes without Co, as shown in Li4/3-2/3x Mn2/3-1/3x NixO2 (0<x<1/2). LiNi0.5Mn0.5O2(x=1/2, LNMO) combines high capacity and thermal stability. It is well known that disordering of Li and Ni in the layered NaCl-type structure occurs during sintering and that oxide ions involve in charge compensation at higher voltages. Accordingly, the electrochemical properties vary depending on the amount of Ni substitution and excess Li relative to the transition metal in conventional Li-ion battery. Therefore, we have investigated an Ox-ASSB battery using LNMOs as a positive electrode, specifically focusing on effects of both Li, Ni-disordering and their sintering temperatures on the performance while controlling chemical compositions precisely.ExperimentalLNMO were prepared by co-precipitation method. The precursor Ni and Mn hydroxides ware prepared from Ni(NO3)2･6H2O and Mn(NO3)2･6H2O. The precursor and LiOH･H2O were mixed to a specified chemical composition ratio, formed under pressure, and calcined at 1073, 1173, 1273 K to obtain LNMO. The solid electrolyte LGVO was synthesized by sintering a mixture of Li4GeO4 and Li3VO4 at 973 K. The LNMO composite cathode layer on LGVO was prepared by applying a composite LNMO cathode slurry, drying, and sintering at 1023K for 6 hours The solid electrolyte LGVO and cathode material LNMO contain 5 % Li3BO3 as a sintering aid. The crystalline phase was identified by powder X-ray diffraction measurement by CuKα radiation. The chemical bonding state was analyzed by X-ray photoelectron spectroscopy Electrochemical testing was performed by LNMO/ LGVO / sulfide solid electrolyte Li10GeP2S12 / In-Li cell (Φ10mm) at 323 K. The rate of constant current was 1/100 C in the 2.0-(3.6~4.0) V.Results and discussionThe samples sintered at 1073, 1173, and 1273 K showed a single phase of LiNi0.5Mn0.5O2. The I (003)/I (104) intensity ratio of Bragg peak, which is an index of the degree of disordering of Li and Ni, increased with increasing sintering temperature. The disordering of Li and Ni in the layered NaCl-type structure occurred with increasing sintering temperature. Fig. 1 shows the charge-discharge measurement results of Ox-ASSB using LNMO (x=1/2) sintered at 1173 K. Followed by a single phasic reaction, a plateau is observed around 3.9 V, the discharge capacities are 175 mAhg-1 at the end-of-charge voltage of 3.6 V and more than 250 mAhg-1 at 4.0 V. Compared to conventional LiB using a liquid electrolyte, this LNMO shows a higher specific capacity, suggesting a possibility to have stable charge-discharge behaviors with LGVO solid electrolyte. These results will be discussed based on the analysis of the cell resistance and the chemical bonding states by XPS measurements before and after charging and discharging. We will present results of other Li-rich positive electrodes in Ox-ASSBs while focusing on a role of oxide ions during and charging-discharging. Figure 1

Development of Highly Adhesive and Conductive Polymers As Primer Coating Layer for Stable Large-Area Lithium Metal Powder Electrode

Faced with the challenges of conventional extrusion and pressing methods, which are limited in producing thinner and wider electrodes due to the malleability of lithium (Li) metal, this research pioneered a slurry-based coating process for lithium metal powder (LMP) electrodes. This innovative approach offers a solution to existing manufacturing constraints by enabling the production of wider and ultra-thin lithium anodes through simple adjustments to the coater settings. Despite the advantages of this method, challenges such as the separation of the LMP composite layer from the collector due to electrolyte impregnation and volume changes during charge/discharge cycles remain significant. To address these issues, an adhesively conductive polymeric interlayer (ACL) was synthesized from 3,4-ethylenedioxythiophene (EDOT) and acrylic acid functional group. The prepared polymer layer could significantly improve the interfacial stability of the electrode. With the application of the ACL, the lithium stripping overpotential was reduced by 60% from 0.0898 V to 0.0358 V. Additionally, improved cycling stability of 200 cycles was achieved with 91% capacity retention at a discharge rate of 4 mA cm-2 in a carbonate-based electrolyte. The successful fabrication of a 300 mm wide and 20 μm thick slurry-coated LMP electrode is a significant advancement for lithium metal batteries (LMBs) and signifies progress in enhancing the energy density of battery technology.

Adsorption of Organic Molecules at Solid-Electrolyte Interface – the Effect of the Electrolyte and Electrode Structure

Understanding processes at the molecular level at the solid-liquid interface is essential to improving and developing novel technologies in electrochemistry, molecular electronics, catalysis, corrosion inhibition, electrodeposition of metals, formation of composite layers, and energy storage devices. Self-assembled monolayers (SAMs) play a significant role in many of those applications and their improvements [1-2]. At the same time, the characteristics of SAMs depend on many aspects, like the characteristics of individual molecules forming the monolayer, the interactions between these molecules, SAM interactions with the electrolyte, the crystalline surface of the substrate, etc.The adsorption of bipyridines resulting in the formation of various nanostructures at the electrode surface has been studied in both aqueous electrolytes [2-5] and, more recently, in IL medium [6-8]. The adsorption of bipyridines is of interest as it offers insight into the interactions which drive the formation of self-assembled monolayers. This is due to aromatic nitrogen-containing heterocycles, which facilitate the possibility of interacting with the surface or other molecules through nitrogen lone electron pair, π-π stacking or hydrogen bonds.To this day, the universal understanding that the adsorption of organic molecules results in the formation of an ordered monolayer is based on the phenomenon observed in mainly aqueous solutions. However, the conception might not be straightforwardly transferrable to the organic additive + ionic liquid | electrode interface. For example, the existence of an interfacial multilayer structure of pure IL ions in contrast with an aqueous electrolyte has been previously shown in both experimental and computational studies. Furthermore, it has been shown that in ILs, if the ions form rigid layers on the electrode, it is necessary to apply an overpotential for interfacial restructuring.This work compares the adsorption of 4,4′-BP and 2,2′-BP at the interfaces between various metal single crystal electrodes (Sb, Bi, Au, Cd) and aqueous or ionic liquid electrolytes. The adsorption process has been studied by applying scanning tunnelling microscopy, electrochemical impedance spectroscopy and cyclic voltammetry methods. Based on the comparison, similarities and differences between aqueous and ionic liquid as electrolytes will be pointed out. Additionally, the influence of the physical and chemical properties of the various metal single crystal electrodes will be discussed.[1] D. R. MacFarlane, et al., Energy Environ. Sci. 7, 232–250 (2014)[2] N.V. Plechkova et al., Chem. Soc. Rev. 37, 123–150 (2008)[3] Pikma et al., Electrochem. Commun. 2015, 61 (Supplement C), 61–65.[4] H. Ers et al., Electrochim. Acta 2022, 421, 140468.[5] H. Ers et al., J. Electroanal. Chem. 2021, 903, 115826.[6] L. Siinor et al., Electrochem. Commun. 2013, 35, 5–7.[7] L. Siinor et al., J. Electroanal. Chem. 2014, 719, 133–137.

Optimization of Cathode Catalyst Layer Composition of Polymer Electrolyte Fuel Cell for Maximum Cell Performance Using Machine Learning and Genetic Algorithm

The Polymer electrolyte fuel cell (PEFC) is a promising technology for power generation, noted for its potential as a zero-carbon technology at the point of use. However, PEMFC faces challenges that must be addressed to enhance its viability, such as its high cost and inefficient output power density. A key component influencing these factors is the cathode catalyst layer (CCL), which is critical for the mass transport flux and electrochemical reactions within the fuel cell. A strategy to lower costs while maintaining performance involves optimizing the CCL composition, including the ionomer-to-carbon (I/C) ratio, Pt-to-carbon (Pt/C) ratio, CCL thickness, and the type of carbon black used, alongside minimizing the Pt loading. Such optimization involves consideration of multiple factors and, consequently, adjusting the CCL composition might have a high potential to balance cost and performance. In this study, therefore, our goal is to propose an optimized catalyst composition that enables high-cell performance with low Pt loading. In particular, we integrated a surrogate machine learning model with an optimization algorithm to determine the optimization of CCL composition.The composition of each CCL is characterized by several variables, including the Pt/C and I/C, the thickness of the catalyst layer, the ionomer coating condition (uniform and non-uniform coatings), and the type of carbon used, which varied between porous (Ketjen) and non-porous (Vulcan) carbon [1]. These variables and output power density were assigned as input and output variables of the machine learning models, respectively. The dataset for the machine learning model was prepared by conducting cell performances with various CCL compositions by the multi-block method detailed in our previous work [2,3]. A total of 390 simulations were used as the dataset, with 312 data points used for training and 78 data points for testing.An assembled machine-learning algorithm known as Extreme Gradient Boosting (XGB) was employed to develop the surrogate model. To identify the optimal CCL composition that generates the highest output power density at a given Pt loading, the XGB-based surrogate model was integrated with an optimization algorithm based on the genetic algorithm (GA). In particular, the fitness of each individual within the GA population is determined by the XGB-based surrogate model, and the GA iteratively evaluates the fitness using operations such as selection, crossover, and mutation, to converge toward the composition that results in the highest power density.The performance of the XGB-based surrogate model in predicting cell performance is validated by its root mean squared error (RMSE) and square correlation coefficient (R²) on the test set, which are 0.07 and 0.89, respectively. This means the cell performance can be predicted by the surrogate model. In the importance feature analysis, the I/C ratio, carbon type, and thickness were identified as the most important parameters of CCL structures. This suggests that we can reduce the Pt load by optimizing the I/C ratio, CCL thickness, and type of carbon black. From the GA results, an optimal starting Pt loading of 0.25 mg/cm² was refined by adjusting the I/C ratio to 0.95, selecting Vulcan as the carbon type, and setting the CCL thickness to 6.54 µm. Through optimization, the Pt load was successfully reduced to 0.198 mg/cm², while maintaining the same power density as the initial loading of 0.25 mg/cm². This outcome highlights the efficacy of the surrogate model and optimization approach in enhancing the cost-efficiency of PEMFCs without compromising their performance.AcknowledgmentsThis research was supported by the New Energy and Industrial Technology Development Organization (NEDO), Japan (grant number P20003-20001327-0).

(Invited) Nano-Engineered SEI Layers for Next Generation Lithium-Ion Batteries

The quest for high-performance lithium-ion batteries (LIBs) hinges on the continuous improvement of cathode materials. Dr. Marca Doeff's seminal contributions have propelled this approach, inspiring novel cathode materials. By studying the intricate interactions between cathode particles, coatings, and the solid electrolyte interphase (SEI) layer, we aim at engineering a high-energy-density and long-lasting next generation lithium-ion battery.We explore the latest advancements in cathode materials, with a focus on LiFePO4, LiMnFePO4, NCM811, and Li-S, introducing surface modifications by graphene and ALD coatings.Dr. Doeff's research has demonstrated the efficacy of carbon coatings in enhancing the rate capability and cycling stability of LFP-based batteries [1].NCM811 is the most promising cathode material due to its high specific capacity and energy density, however, issues such as structural instability and capacity fading hinder its practical application. Through meticulous optimization of ALD coatings, our group has mitigated these challenges, leading to enhanced electrochemical performance and prolonged cycle life [2].Li-S batteries offer a high theoretical specific capacity and low cost, making them attractive candidates for next-generation energy storage systems, however, polysulfide dissolution and shuttle effects pose significant challenges, limiting their practical viability.By leveraging ALD techniques, our group has engineered active coatings to enhance polysulfides conversion and stabilize the cathode cycling ability.The formation and stability of the SEI layer play a pivotal role in dictating the overall performance and safety of lithium-ion batteries. Graphene coatings and ALD treatments exert a profound influence on SEI layer formation, influencing ion transport kinetics, surface reactions, and interfacial stability.Graphene coatings not only enhance electronic conductivity but also modulate the SEI layer composition and morphology. Through synergistic interactions with electrolyte components, graphene coatings promote the formation of a robust and homogeneous SEI layer, thereby suppressing parasitic reactions and capacity degradation.ALD-enabled coatings offer precise control over film thickness and composition, enabling engineered interfaces with superior electrochemical performance. By depositing conformal ALD layers onto cathode surfaces, we can engineer SEI layers with enhanced chemical stability and ion permeability, leading to improved cyclability and safety.Dr. Marca Doeff's enduring legacy in lithium-ion battery research continues to inspire groundbreaking advancements in cathode material engineering. Through meticulous design and characterization of the cathode SEI layer, coupled with innovative materials engineering techniques, we are positioned at the forefront of electrochemistry to produce batteries with enhanced performance and cycle life.[1] MM Doeff et al. "Optimization of carbon coatings on LiFePO4," Journal of Power Sources 163 (1), 2006, 180-184.[2] D Mohanty et al. “Modification of Ni-Rich FCG NMC and NCA Cathodes by Atomic Layer Deposition: Preventing Surface Phase Transitions for High-Voltage Lithium-Ion Batteries,” Sci Rep 6, 26532 (2016).

Binary Solvent Induced Stable Interphase Layer for Ultra-Long Life Sodium Metal Batteries

Lithium-ion batteries (LIBs) face concerns about production capacity and critical material shortages in the pursuit of reliable energy storage for intermittent renewable sources.1,2 As an alternative, sodium-ion batteries (SIBs) offer a comparable storage mechanism using abundant and cost-effective sodium as the energy host.3 With sodium's abundance surpassing lithium by ≈1000 times, SIBs present a compelling solution for future energy storage needs.1 Sodium metal boasts a high theoretical capacity of 1166 and 1131 mA h cm−3, coupled with a low redox potential of −2.71 V versus standard hydrogen electrode (SHE).4 These attributes pave the way for exploring the potential applications of metal anode-based batteries in energy density-intensive electric vehicles and more efficient stationary storage systems for renewable energy sources.5 However, addressing the challenges associated with parasitic reactions involving alkali metal anodes is essential. These reactions can lead to the formation of unstable solid electrolyte interphase (SEI) and dendrites, which not only diminish battery longevity but also pose safety hazards.6 The past decade has seen extensive research efforts aimed at achieving stable cycling of sodium metal batteries (SMBs), addressing challenges like parasitic reactions and dendrite formation.1,7,8 Various strategies, including the use of additives,4 artificial SEI formation,9 and directed sodium deposition,10 have been explored to enhance SMB lifespan. Notably, modifying the electrolyte composition, particularly the choice of solvent, stands out as a straightforward yet practical approach.8 Solvent selection significantly influences the physical and chemical properties of the electrolyte, impacting salt solvation and SEI layer formation. Recent studies have shown promising results with ether-based solvents such as diglyme (Dig) and tetrahydrofuran (THF), promoting stable SEI layer formation due to the presence of aggregates (AGGs) solvation structure.7,11 However, the sustainability of high salt concentrations remains a concern due to cost implications and limited ionic conductivity.8,12 Here, solvent engineering offers a solution by adjusting the mixture ratio of solvents to create localized high-concentration electrolytes, enhancing SMB stability.8,13 Furthermore, environmentally friendly solvents like 2-methyl tetrahydrofuran (MTHF) present a promising co-solvent option, offering weaker Na⁺ ion solvation characteristics and lower viscosity, potentially improving SMB performance, especially at lower salt concentrations.14,15 Hence, introducing MTHF as a co-solvent to Dig holds the potential to enhance SMB rate capability and stability, even at reduced salt concentrations.In this study, a stable sodium metal battery (SMB) is achieved by tuning the electrolyte solvation structure through the addition of co-solvent 2-methyl tetrahydrofuran (MTHF) to diglyme (Dig). The introduction of cyclic ether-based MTHF results in increased anion incorporation in the solvation structure, even at lower salt concentrations. Specifically, the anion stabilization capabilities of the environmentally sustainable MTHF co-solvent lead to a contact-ion pair-based solvation structure. Time-of-flight mass spectroscopy analysis reveals that a shift toward an anion-dominated solvation structure promotes the formation of a thin and uniform SEI layer. Consequently, employing a NaPF6-based electrolyte with a Dig:MTHF ratio of 50% (v/v) binary solvent yields an average Coulombic efficiency of 99.72% for 300 cycles in Cu||Na cell cycling. Remarkably, at a C/2 cycling rate, Na||Na symmetric cell cycling demonstrates ultra-long-term stability exceeding 7000 h, and full cells with Na0.44MnO2 as a cathode retain 80% of their capacity after 500 cycles. This study systematically examines solvation structure, SEI layer composition, and electrochemical cycling, emphasizing the significance of MTHF-based binary solvent mixtures for high-performance SMBs. References G. G. Eshetu et al., Adv. Energy Mater., 10, 2000093 (2020). Energy Storage Assoc. https://energystorage.org/why-energy-storage/benefits/.C. Delmas, Adv. Energy Mater., 8, 1703137 (2018).B. Sun et al., Adv. Mater., 32, 1903891 (2020).U.-H. Kim et al., ACS Energy Lett., 7, 3880–3888 (2022).B. Lee, E. Paek, D. Mitlin, and S. W. Lee, Chem. Rev., 119, 5416–5460 (2019).L. Zhu et al., Green Energy Environ., 8, 1279–1307 (2023).Z. Tian et al., Adv. Sci., 9, 2201207 (2022).Z. W. Seh, J. Sun, Y. Sun, and Y. Cui, ACS Cent. Sci., 1, 449–455 (2015).Z. Sun et al., Small, 18, 2107199 (2022).R. Cao et al., Nano Energy, 30, 825–830 (2016).Y. Li et al., ACS Energy Lett., 5, 1156–1158 (2020).J. Zheng et al., ACS Energy Lett., 3, 315–321 (2018).C.-C. Su, M. He, R. Amine, Z. Chen, and K. Amine, Angew. Chem. Int. Ed., 57, 12033–12036 (2018).D. Guo, J. Wang, T. Lai, G. Henkelman, and A. Manthiram, Adv. Mater., 35, 2300841 (2023). Figure 1

(Invited) Investigating ALE Approaches for Novel Metal Oxide Patterning at Sub-100 Nm Pitch for High-Density Memory & Compute Applications

Atomic layer etching (ALE) continues to garner wide attention as a technique for controlled patterning of different materials.1,2 However, a substantial amount of these studies are carried out on blanket films. It is therefore pivotal to investigate the feasibility of ALE for patterning high-density features as it exhibits the potential to be the preferred etching method for novel materials in the semiconductor industry.This talk will focus on the impact of ALE in the patterning of complex metal oxides like InGaZnO and MgZnO. These metal oxides are potential contenders as channel materials in high-performing transistors for memory and compute applications.3 Therefore, several critical criteria need to be followed when ALE conditions are being defined. The channel needs to be patterned with minimal physical and chemical damage such that there is little or no impact on the mobility parameters of the channel.The etching process should not induce redeposition onto the hard mask which also acts as a top contact in an integrated stack within the chip. In the case of InGaZnO, ALE-based patterning down to pitch 36 nm will be discussed in a systematic fashion.4 At such scaled pitches, it is observed that the etching challenges highlighted above cannot be resolved completely by ALE itself. Therefore, ALE in conjunction with other patterning approaches such as plasma pulsing needs to be employed to achieve satisfactory etching of the features at pitch 36 nm.On the other hand, when the metal oxide layer comprises a non-volatile element like Mg (in MgZnO), the etching mechanism tends to be both physical and chemical. In this case, it is still seen that the ALE approach provides a more controlled way of removing the layer without damaging the layer composition when compared to its conventional counterpart – reactive ion etching (RIE) at pitch 90 nm.5 REFERRENCES (1) Metzler, D.; Bruce, R. L.; Engelmann, S.; Joseph, E. A.; Oehrlein, G. S.; Fluorocarbon Assisted Atomic Layer Etching of SiO2 Using Cyclic Ar/C4F8 Plasma. J. Vac. Sci. Technol. A 2014, 32, 020603.(2) Metzler, D.; Li, C.; Engelmann, S.; Bruce, R. L.; Joseph, E. A.; Oehrlein, G. S.; Fluorocarbon Assisted Atomic Layer Etching of SiO2 and Si Using Cyclic Ar/C4F8 and Ar/CHF3 plasma. J. Vac. Sci. Technol. A 2016, 34, 01B101.(3) Belmonte, A.; Oh, H.; Rassoul, N.; Donadio, G. L.; Mitard, J.; Dekkers, H.; Delhougne, R.; Subhechha, S.; Chasin, A.; van Setten, M. J.; Kljucar, L.; Mao, M.; Puliyalil, H.; Pak, M.; Teugels, L.; Tsvetanova, D.; Banerjee, K.; Souriau, L.; Tokei, Z.; Goux, L.; Kar, G. S.; Capacitor-Less, Long-Retention (>400s) DRAM Cell Paving the Way towards Low-Power andHigh-Density Monolithic 3D DRAM. 2020 IEEE International Electron Devices Meeting (IEDM) 2020, pp. 28.2.1-28.2.4.(4) Kundu, S.; Decoster, S.; Bezard, P.; Mehta, A. N.; Dekkers, H.; Lazzarino F.; High-Density Patterning of InGaZnO by CH4: a Comparative Study of RIE and Pulsed Plasma ALE. ACS Appl. Mater. Interfaces 2022, 14, 29, 34029–34039.(5) Ghorbani, L.; Kundu, S.; De Gendt, S.; Manuscript in preparation.

Na-Ion Battery Based on Carbon and Phosphate Chemistries

Lithium-ion batteries are one of the most used power sources in a variety of fields: microelectronics, portable devices, automotive or even stationary energy storage. The huge growth of the Li-ion battery market raises concerns about the limited availability of lithium resources and its rising cost of acquisition. To counteract that effect, scientists again focused on sodium, as a cheaper and easily acquirable element to use in electrochemical power sources [1, 2].In principle, sodium-ion batteries operate through similar mechanisms as lithium-ion cells, where Na+ ions are charge carriers between negative and positive electrodes. Most of the electrode materials used in the Na-ion technology come from their widely used analogues in Li-ion systems. However, due to differences in ion transport, reaction kinetics and Solid Electrolyte Interphase layer composition, there is a need for extensive studies to be carried out before the wide commercialisation of Na-ion batteries can take place [2].In this presentation, we show our results from research on Na-ion battery systems, based on carbon and phosphate chemistries. From the negative electrode side, carbonaceous materials prepared in our lab showed good capacities (ca. 200 mAh g-1), outstanding cyclability and high-rate performance (above 95% and 50% capacity retention during cyclability and high-rate tests, respectively). For the positive electrode, transition metal phosphates obtained through various synthetic routes also showed excellent performance (above 95% and 95% capacity retention during cyclability and high-rate tests, respectively) in Na-ion cells. Materials with the best electrochemical performances were used to construct a full Na-ion battery, which showed promising results in full-cell geometry and the feasibility of carbon and phosphate chemistries in the development of post-lithium battery systems. Acknowledgements: This work was supported by The Polish National Centre of Science through a research grant 2021/43/D/ST5/01220 entitled “High-voltage sodium-ion batteries based on exfoliated graphite electrodes”.Literature:[1] Jamesh, M. I. & Prakash, A. S. J. Power Sources 378, 268–300 (2018).[2] Delmas, C. Adv. Energy Mater. 8, 1–9 (2018).

Dielectric high gradient insulator – Progress towards multilayer insulating structures

High gradient insulators (HGI) consisting of ceramic and metallic alternating layer structure, have been shown to reduce surface breakdown occurrence in high voltage devices. Recently, the HGI's metal layers were replaced with high dielectric constant ceramics, creating dielectric high gradient insulators (DHGI) that were shown to outperform pure alumina analog. A 2-layer DHGI prototype manufactured by spark plasma sintering (SPS) demonstrated an increased surface breakdown field and fewer surface breakdowns during conditioning, compared to plain alumina. However, weak breakdowns at the opposite polarity were observed in the 2-layer structure. This study focuses on overcoming this issue by introducing a 3-layer design, with two high dielectric layers capping a plain alumina layer. Breakdown tests confirmed the elimination of weak breakdowns and improved dielectric strength, consistent with simulations predictions. Additionally, post-SPS air annealing was shown to be essential for removing adsorbed gases and recovering the high dielectric layers composition that changed during SPS. The annealed DHGIs were shown to reduce significantly the breakdown pulses during high-voltage conditioning. The 3-layer DHGI exhibited a 33.5 % higher breakdown field than plain alumina and a 13.5 % improvement over the 2-layer DHGI reported earlier.

Free vibration optimization of 2D tri-axial braided composite fan blade with ANN-Anal-FEM-GA integrated model

This research aimed to increase the natural frequencies of a non-rotating 2D tri-axial braided composite (2DTBC) fan blade. The investigation utilized a multidisciplinary approach, integrating Artificial Neural Network (ANN) modeling, analytical method, Finite Element (FE) analysis, optimization techniques, and experimental validation. The ANN captured the complex relationship between the braiding machine and structure parameters. The mechanical properties of the 2DTBC were determined through the micromechanical modeling, and the thin-shell analysis was applied to describe the blade’s displacement and strain characteristics. Micromechanical modeling examines material behavior at the microscopic level, and thin shell analysis focuses on modeling and analyzing thin, curved structures using simplified equations. The FE method facilitated the formulation of the equation of motion and the calculation of natural frequencies. A genetic algorithm, focused on a single-objective optimization, was employed to refine the braiding structure parameters and the number of composite layers, thereby enhancing the blade’s natural frequencies. The optimized 2DTBC blade was subsequently fabricated and validated through impact hammer modal testing, showing strong agreement with the predictions from the combined ANN-analytical-FEM-GA model. The optimization of the braiding parameters led to a significant increase in the blade’s natural frequencies.

Simplified Composite Restorations for Fractured Young Incisors: A Clinical Review.

Tooth fractures are a common consequence of dental trauma in young patients, requiring prompt and effective restorative interventions that ensure both functional integrity and esthetic appeal. Although resin stratification (layering) is the gold standard for achieving life-like restoration of fractured teeth, many clinicians find it technically challenging due to the time and effort required for precise shade matching, concealing the fracture line, and accurate placement of resin composite layers with different levels of opacity. The more recent generation of monoshade composites, with their ability to adapt to various tooth shades, reduce the complexity of multi-layer restorations, and improve chairside efficiency. Additionally, the composite cutback technique has gained attention as an effective method for restoring fractured teeth in young patients. This method combines the benefits of monoshade composites and the precision of simple additional layering to enhance both the esthetic and functional outcomes of the restorations. This mini-review provides a comprehensive analysis of the composite cutback technique, the role of monoshade composites, and their clinical application in the restoration of fractured young teeth.

Optimization of low-velocity impact behavior of FML structures at different environmental temperatures using taguchi method and grey relational analysis

Carbon fiber-reinforced Aluminum Laminate (CARALL) is a new generation of Fibre Metal Laminate (FML) material. This study investigates the low-velocity impact behavior of CARALL structures at different environmental temperatures (−40°C, 23°C, and 80°C). Two different groups of CARALL composite structures with varying fiber orientations were produced by hot pressing in a 3/2 arrangement: C1 (Al/0°90°/Al/90°0°/Al) and C2 (Al/0°0°/Al/0°0°/Al). Low-velocity impact tests were conducted at 23 J, 33 J, and 48 J energy levels using a Ø20 mm spherical impactor tip. The area of damage was detected by ultrasonic C-Scan. In addition, analysis of variance (ANOVA) was applied to reveal the influential parameters and their effect levels. After conducting experiments using the Taguchi L18 test set, it was observed that the C2-coded specimen yielded better results in terms of maximum peak load, maximum displacement, and damage area. While the decrease in temperature increased the damage and maximum peak load, the increase in temperature did not cause a significant change in the maximum peak load. The primary damage mechanisms observed in damage investigations were matrix cracks and delamination between composite layers. Although delamination is present between the Al/CFRP layer, it is not significant. According to ANOVA results, impact energy was the most effective parameter for maximum impact force, maximum displacement, and damage area, with contribution rates of 81%, 74%, and 76%, respectively. The optimal experimental conditions (23°C temperature and 23 J impact energy with the C1-coded sample) were determined using grey relational analysis based on principal component analysis.

Combining electrical resistivity tomography and passive seismic to characterise the subsurface architecture of a deeply weathered lateritic hill within the Avon River critical zone observatory

AbstractObserving the subsurface architecture of the deep Critical Zone (CZ), which lies beyond the uppermost layer of accessible soil, is a complex but crucial task. Near‐surface geophysics offers an alternative to accessing the deep CZ at scales relevant to fluid, nutrient and gas transport. As geophysical instruments are sensitive to different subsurface physical properties, their combination can enhance insight into CZ architecture. However, the agreement between and complementarity of multiple geophysical techniques has not been widely assessed for CZ‐related questions. This study employed geophysics to image a highly weathered lateritic hill rich in iron oxides developed from Archean granite within the Avon River Critical Zone Observatory, Western Australia. Data gathered from an electrical resistivity tomography (ERT) and horizontal‐to‐vertical‐spectral‐ratio (HVSR) passive seismic transect were used to visualise CZ architecture through specific resistivity values and ambient noise contrasts. Both techniques revealed a notable degree of lateral variability consistent with the formation of the ~3–4 m thick duricrust‐capped hilltop, the creation of gullies in the sodic material of the pallid zone exposed along the slope and the deposition of ~11 m thick colluvial sediment at the foot slope. Calculated bedrock depth was consistent between the HVSR and ERT instruments along the hilltop plateau but varied from ~23 m to 31 m on the slope and 32 m to 39 m at the foot slope, respectively. Overall, the vertical variation depicted by the ERT, including the differentiation of two layers within the lateritic weathering profile ‐ the pallid zone and saprolite – made up for the inaccuracy of the HVSR technique in depicting layers of similar composition. Moreover, the HVSR method clearly depicted bedrock depth, overcoming the partial masking of the bedrock by saline groundwater in the ERT model. The complementarity of these two methods allowed the development of a detailed conceptual model of subsurface CZ architecture within a saline lateritic weathering profile.

Advancing Human–Machine Interface (HMI) through Development of a Conductive‐Textile Based Capacitive Sensor

AbstractSmart wearable sensors in human–machine interfaces (HMI) facilitate communication and interface between humans and robots, as well as among humans. Conventional wearables face significant limitations, including performance degradation under various deformations (e.g., strain and pressure), limited stretchability and flexibility, poor comfort, and breathability, complicating their integration into HMI applications. In response to these limitations, a smart, sewable, high‐precision HMI device based on a soft, textile‐based sensor with machine learning (ML)‐assisted data processing is proposed. The (Ag)‐based fabric electrode integrated into polymeric composite dielectric layer, exhibiting hysteresis error of (≤4%), a tensile strain sensitivity of gauge factor (GF) ≃ 1.03 at 100% elongation, a pressure sensitivity of ≈1.583 × 10−2 kPa−1 at pressures (&lt;50 kPa) and excellent stability (&gt;1000 cycles). To demonstrate its versatility in HMI, the textile‐based sensor is integrated into a glove for real‐time control of a commercially available prosthetic hand and a drone, as well as for sign language recognition, achieving 95.4% classification accuracy using the random forest (RF) classifier across 10 gestures. Beyond gesture recognition, the sensor measures a range of subtle physiological activities (&gt;0.35 kPa), functioning as a force myograph, esophageal manometry, and in gait analysis, among other strain and pressure‐related applications, highlighting exceptional capabilities for advanced wearable systems.

Time-Dependent Material Properties and Composition of the Nonhuman Primate Uterine Layers Through Gestation.

The uterus is central to the establishment, maintenance, and delivery of a healthy pregnancy. Biomechanics is an important contributor to pregnancy success, and alterations to normal uterine biomechanical functions can contribute to an array of obstetric pathologies. Few studies have characterized the passive mechanical properties of the gravid human uterus, and ethical limitations have largely prevented the investigation of mid-gestation periods. To address this key knowledge gap, this study seeks to characterize the structural, compositional, and time-dependent micro-mechanical properties of the nonhuman primate (NHP) uterine layers in nonpregnancy and at three time-points in pregnancy: early 2nd, early 3rd, and late 3rd trimesters. Distinct material and compositional properties were noted across the different tissue layers, with the endometrium-decidua being the least stiff, most viscous, least diffusible, and most hydrated layer of the NHP uterus. Pregnancy induced notable compositional and structural changes to the endometrium-decidua and myometrium, but no micro-mechanical property changes. Further comparison to published human data revealed notable similarities across species, with minor differences noted for the perimetrium and nonpregnant endometrium. This work provides insights into the material properties of the NHP uterus and demonstrates the validity of NHPs as a model for studying certain aspects of human uterine biomechanics.

Efficient Synergy of Sea Urchin-like Graded Structure Supercapacitor Electrodes by Modulating the Morphology of Layered Double Hydroxide Composites

Efficient Synergy of Sea Urchin-like Graded Structure Supercapacitor Electrodes by Modulating the Morphology of Layered Double Hydroxide Composites