bluuebunny/crossref_metadata_2025 huggingface dataset:
Parental satisfaction with waiting time in a Swiss tertiary paediatric emergency department
Authors: Löflath Viola , Hau Eva-Maria , Garcia Daniel , Berger Steffen , Löllgen Ruth
Published: December 2020

Introduction

Patient numbers in paediatric emergency departments (PED) are steadily increasing. Parental perception of waiting time and reasons for attending a PED with non-emergencies have been investigated in the UK, Australia, Korea, Canada and the USA. We sought to examine which factors influence parental satisfaction with waiting time in a tertiary Swiss PED and whether these differed from other countries.

Methods

Paper surveys were administered to parents of children presenting to our interdisciplinary PED from February to May 2015. Primary outcome was parental satisfaction with waiting time, secondary outcomes were satisfaction with treatment, parental reasons for presentation with non-emergencies, parental perception of times to triage, first physician contact and disposition from ED, level of physician training, understanding of various anticrowding strategies and comparison of perceived and true waiting times to triage and physician contact.

Results

739 out of 750 surveys were returned (57 complete, 298 with 1 or 2 missing answers). Satisfaction with waiting time (on a 5-point-Likert-scale; 1 being the best possible answer) was higher in groups with shorter waiting time until triage (+0.41, p=0.001), first physician contact (+1.43, p<0.001) and discharge (+0.71, p<0.001), higher triage category urgency (+0.47, p=0.044) and available entertainment (+0.82, p<0.001). Early first physician contact (+0.33, p=0.008) and time to discharge less than 4 hours (+0.37, p<0.001) was associated with greater satisfaction with treatment (p<0.05). The most frequent reasons for presentation were parental impression that the child had an emergency (n=265, 35.9%) and referral by the family doctor (n=245, 33.2%).

Conclusion

To counteract parental dissatisfaction associated with waiting time, we suggest the implementation of feasible measures including entertainment while waiting, early first medical review and timely discharge from the PED.
S100B protein level for the detection of clinically significant intracranial haemorrhage in patients with mild traumatic brain injury: a subanalysis of a prospective cohort study
Authors: Blais Lécuyer Julien , Mercier Éric , Tardif Pier-Alexandre , Archambault Patrick M , Chauny Jean-Marc , Berthelot Simon , Frenette Jérôme , Perry Jeff , Stiell Ian , Émond Marcel , Lee Jacques , Lang Eddy , McRae Andrew , Boucher Valérie , Le Sage Natalie
Published: December 2020

Background

Clinical assessment of patients with mild traumatic brain injury (mTBI) is challenging and overuse of head CT in the ED is a major problem. Several studies have attempted to reduce unnecessary head CTs following a mTBI by identifying new tools aiming to predict intracranial bleeding. Higher levels of S100B protein have been associated with intracranial haemorrhage following a mTBI in previous literature. The main objective of this study is to assess whether plasma S100B protein level is associated with clinically significant brain injury and could be used to reduce the number of head CT post-mTBI.

Methods

Study design:secondary analysis of a prospective multicentre cohort study conducted between 2013 and 2016 in five Canadian EDs.Inclusion criteria:non-hospitalised patients with mTBI with a GCS score of 13–15 in the ED and a blood sample drawn within 24 hours after the injury.Data collected:sociodemographic and clinical data were collected in the ED. S100B protein was analysed using ELISA. All CT scans were reviewed by a radiologist blinded to the biomarker results.Main outcome:the presence of clinically important brain injury.

Results

476 patients were included. Mean age was 41±18 years old and 150 (31.5%) were women. Twenty-four (5.0%) patients had a clinically significant intracranial haemorrhage. Thirteen patients (2.7%) presented a non-clinically significant brain injury. A total of 37 (7.8%) brain injured patients were included in our study. S100B median value (Q1–Q3) was: 0.043 µg/L (0.008–0.080) for patients with clinically important brain injury versus 0.039 µg/L (0.023–0.059) for patients without clinically important brain injury. Sensitivity and specificity of the S100B protein level, if used alone to detect clinically important brain injury, were 16.7% (95% CI 4.7% to 37.4%) and 88.5% (95% CI 85.2% to 91.3%), respectively.

Conclusion

Plasma S100B protein level was not associated with clinically significant intracranial lesion in patients with mTBI.
Telemedicine in the emergency department to decrease personal protective equipment use: a before-and-after study
Authors: Candel Bart G J , Vaes Selma M M , van Bree Egid M , Groenen Sophie M A , Derkx Floor , Mignot Lisette A A , de Groot Bas
Published: December 2020

Background

Personal protective equipment (PPE) used by healthcare workers was scarce during the COVID-19 pandemic.The aim of this study was to assess whether telemedicine (using iPads) reduced PPE use in emergency department (ED) patients who were treated in contact isolation, and whether telemedicine had a positive effect on patient anxiety and satisfaction.

Methods

We conducted a prospective single centre before-and-after study including ED patients ≥18 years who were treated in contact isolation. PPE use, the Hospital Anxiety Scale and the 15-item Picker Patient Experience Questionnaire were compared between the control period (8 April to 14 April 2020) and intervention period (15 April to 24 April 2020).

Results

We included 25 patients in each period. PPE use per patient was higher for physicians in the control period (mean 1.7; 95% CI 1.5 to 1.9) compared with the intervention period (mean 1.2; 95% CI 1.0 to 1.3, p<0.01). Total PPE use per patient contact for ED physicians decreased from 42 out of 42 patient contacts in the control period, to 29 out of 66 patient contacts in the intervention period (difference 54.3%; 95% CI 50.1% to 58.6%, p<0.01). Reported anxiety and satisfaction were not significantly different.

Conclusion

PPE use by physicians can successfully be reduced by using telemedicine in the ED without increasing anxiety or dissatisfaction. This study was a first step to gain experience with telemedicine in the ED which has the potential to reduce PPE use in future pandemics or other patients with an indication for contact isolation.
Past Warmth and Its Impacts During the Holocene Thermal Maximum in Greenland
Authors: Axford Yarrow , de Vernal Anne , Osterberg Erich C.
Published: December 2020

Higher boreal summer insolation in the early to middle Holocene drove thousands of years of summer warming across the Arctic. Modern-day warming has distinctly different causes, but geologic data from this past warm period hold lessons for the future. We compile Holocene temperature reconstructions from ice, lake, and marine cores around Greenland, where summer temperatures are globally important due to their influence on ice sheet mass balance, ocean circulation, and sea ice. Highlighting and accounting for some key issues with proxy interpretation, we find that much of Greenland experienced summers 3 to 5°C warmer than the mid-twentieth century in the early Holocene—earlier and stronger warming than often presumed. Warmth had dramatic consequences: Many glaciers disappeared, perennial sea ice retreated, plants and animals migrated northward, the Greenland Ice Sheet shrank rapidly, and increased meltwater discharge led to strong marine water stratification and enhanced winter sea ice in some areas. ▪  Summer air temperatures and open ocean temperatures around much of Greenland peaked in the early Holocene in response to elevated summer insolation. ▪  Peak summer air temperatures ranged from 3 to 5°C warmer than the mid-twentieth century in northwest and central Greenland to perhaps 1 to 2°C warmer in south Greenland. ▪  Many differences between records can be explained by proxy seasonality, ice sheet elevation changes, vegetation analogs and lags, and the nearshore effects of ice sheet meltwater. ▪  Early Holocene warmth dramatically affected glaciers and the Greenland Ice Sheet; meltwater discharge, nearshore ocean salinity, and sea ice; and diverse flora and fauna.
Effect of Ni–Al Coating with and without Re Modification on Coking and Metal Dusting of Fe–Cr–Ni Alloy under Cyclic Condition at 600 °C
Authors: Li Meifeng , Xie Yun , Grzesik Zbigniew , Liu Famin , Zhang Jianqiang , Zhou Chungen
Published: December 2020

Ni–Al coatings with and without Rhenium (Re) modification were prepared using electroplating and packing cementation methods on the matrix of Fe–Cr–Ni alloy. Corrosion behaviours of the matrix alloy and two coated samples were investigated in 30CO–64H2–6H2O gas mixture under thermal cycling condition at 600 °C. All coated samples showed significantly improved corrosion performance. Re addition was ineffective in controlling the surface coking and metal dusting of Ni–Al coating but enhanced the thermal fatigue resistance to thermal cycling. The corrosion mechanism of Ni–Al coating exposed to metal dusting environment under thermal cycling condition and the effect of Re were discussed.
Review—The Lithiation/Delithiation Behavior of Si-Based Electrodes: A Connection between Electrochemistry and Mechanics
Authors: Kim Minkyu , Yang Zhenzhen , Bloom Ira
Published: December 2020

Silicon is a promising alternative anode material to graphite because of its high gravimetric and volumetric energy densities. However, severe capacity fading is observed in Si electrodes, and it is a result of mechanical changes of Si, such as volume changes, stress or fracture. Furthermore, these mechanical behaviors are strongly coupled with the electrochemistry of the Li–Si alloying reaction in Si-based electrodes, including both thermodynamics and kinetics. Therefore, the electrochemical properties of Si-based electrodes are strongly dependent on the control of the mechanics of Si during lithiation/delithiation. Thus, it is very important to understand the correlation between electrochemistry and mechanics. Here, we review lithiation/delithiation behaviors of various types of Si-based electrodes, applying a fundamental understanding of electrochemistry and mechanics and the correlation between them.
Thermodynamic Equivalence Charts for Stress Corrosion Cracking Studies in Hydrogenated Steam, High Pressure and Supercritical Water
Authors: Volpe L. , Curioni M. , Burke M. G. , Scenini F.
Published: December 2020

The evaluation of the materials performance for applications in pressurized water reactors (PWRs) primary water environment are often conducted in either low pressure superheated hydrogenated steam or in supercritical hydrogenated water in order to accelerate the pressurized water stress corrosion cracking (PWSCC) mechanism and reduce experimental time. The high temperature accelerates SCC initiation, which is typically slow under real primary water conditions. However, both in hydrogenated steam and in supercritical hydrogenated water, it is important that the material attains environmental conditions and oxidizing potentials that are relevant to a primary water environment, so that the same PWSCC initiation mechanism operates. The aim of this paper is to establish a thermodynamic equivalence between laboratory systems, namely low pressure superheated hydrogenated steam and supercritical hydrogenated water, and the PWR primary water environments. Experimental data obtained from different sources in the literature are used to obtain thermodynamic relationships as a function of temperature and media. The applicability of these correlations is shown and discussed with examples, and equivalence charts have been generated for practical selection of experimental conditions.
Hydrogen Concentration Control in Oil-Filled Power Transformers Using Field Effect Capacitive Gas Sensors
Authors: Litvinov Artur , Samotaev Nikolay , Etrekova Maya , Ivanova Anastasia , Filipchuk Dmitrii
Published: December 2020

A simple method is demonstrated for hydrogen concentrations measurement directly in transformer oil and in the gas space above it use a highly sensitive (at the level of units and fractions of ppm) gas sensor based on a metal-insulator-semiconductor capacitive structure (MIS sensor). The results obtained can be used in online monitoring systems and predicting the power transformers integral performance, in particular those that have been put into operation long ago, by tracking slow and invisible at the initial stage aging processes of current-carrying connections and structural elements.
Gradient-Regeneration of Li(Ni0.9Co0.05Mn0.05)O2 from Spent LiCoO2 lithium-Ion Battery
Authors: Wang Guange , Wu Tong , Liu Borui , Gong Shanshan , Huang Qing , Su Yuefeng , Wu Feng , Kelly Ryan M.
Published: December 2020

Considering that lithium-ion battery (LIB) is still an indispensable and important component of energy storage materials, the sustainable post-processing of spent LIBs in labs or enterprises becomes a tricky problem. Herein, a novel scheme is proposed to dissert the recycling of the spent LIBs. The LIB is recycled into Li(Ni0.9Co0.05Mn0.05)O2 (NCM90) cathode material with high specific capacity by introducing an innovative hydrometallurgy-coprecipitation treatment method. The spent LiCoO2 (LCO) cathode material is firstly leached by sulfuric acid, and the leachate is gradient used as the raw materials to resynthesize high-nickel NCM material by adjusting the leachate dosage to about 50%. Interestingly, when the dosage exceeds 50%, the crystal structure aggravates, and Li+/Ni2+ mixing improves. The specific capacity of regenerated battery is 181.4 mAh g−1 at 0.5 C (1 C = 200 mAh g−1) and the capacity retention achieves 93.2% after 100 cycles. The reasons can be attributed to the cation mixing and crystal strucure and the small amount of Al doping. In conclusion, this combined method recycling of LIBs has huge potential value for environment protection and production.
The Suppression Effect of Functional Gradient Design on Concentration Polarization of Multiple Cations Molten Salt Electrolyte for Thermal Batteries
Authors: Cao Yong , Gao Chenyang , Yang Xiaowei , Wang Chao , Yan Jun , Shi Donghui , Chen Yong , Cui Yanhua
Published: December 2020

The energy density of traditional Li−Si/FeS2 thermal batteries, which multiple cations are contained in molten salt electrolyte, is limited by the deficiency of Li+ in cathode when a high discharge current is applied. To address this issue, LiCl−KCl is taken as an example to build a functional gradient structure through Li−Si/FeS2 thermal batteries. By levering the Li+ concentration in cathode and preventing the formation of high concentration polarization resistivity as well as molten salt precipitation, the energy density of Li−Si/FeS2 single cell with a discharge current of 500 mA cm−2, increase from 157.0 Wh kg−1 to 218.4 Wh kg−1 at 450 °C (with an increase ratio of 39.1%), compared with the original one. Similarly, a 25.6% raise is observed at 525 °C. Moreover, the effects of LiCl-rich electrolyte and the functional gradient structure on the electrochemical performance of Li−Si/FeS2 single cells are discussed and classified.
Optimal Fast Charging Method for a Large-Format Lithium-Ion Battery Based on Nonlinear Model Predictive Control and Reduced Order Electrochemical Model
Authors: Yin Yilin , Bi Yalan , Hu Yang , Choe Song-Yul
Published: December 2020

Design of an appropriate charging protocol is a challenging issue. Recent emerging charging methods have employed electrochemical models to determine charging protocols. However, these protocols are not otimized considering reduction of charging time and minimization of reaction rates of solid electrolyte phase layer (SEI) formation and lithium plating simultaneously. In this paper, we proposed an optimal fast charging method that simultaneously considers the charging time and the two aging effects in addition to lithium stripping. The optimization is performed using nonlinear model predictive control, where variables in the objective function are the charging time and ion loss caused by SEI layer and constraints are cutoff voltage and lithium ion concentrations. In addition, the charging protocol consists of not only constant currents, but also pulse discharging currents that can recover ions from the lithium metal by lithium stripping, which can further reduce the charging time by allowing increased currents. The designed charging method is verified using Battery-In-The-Loop system and compared with CC/CV charging protocols under a constant temperature. Experimental results have shown significant minimization of capacity fade and the associated extension of cycle life, and effective suppression of the lithium plating.
Electrocatalysis of Lithium (Poly-) Sulfides in Organic Ether-Based Electrolytes
Authors: Ante M. J. , Sörgel Ş. , Opitz M. , Freudenberger R. , Bund A.
Published: December 2020

This work aims at identifying an effective electrocatalyst for polysulfide reactions to improve the electrode kinetics of the sulfur half-cell in liquid organic electrolytes for alkali-sulfur cells. To increase the charge and discharge rates and energy efficiency of the cell, functionalized electrocatalytic coatings have been prepared and their electrode kinetics have been measured. To the best of our knowledge, there is no extensive screening of electrocatalysts for the sulfur electrode in dimethoxyethane:1,3-dioxolane (DME:DOL) electrolytes. In order to identify a suitable electrocatalyst, apparent exchange current densities at various materials (Al, Co, Cr, Cu, Fe, Steel, glassy carbon, ITO, Ni, Pt, Ti, TiN, Zn) are evaluated in a polysulfide electrolyte using potentiodynamic measurements with a Butler-Volmer fit. The chemical stability and surface morphology changes after electrochemical measurements are assessed with X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The results show that cobalt is a promising candidate with appropriate electrocatalytic properties for polysulfide reactions while being stable in the electrochemical environment, followed by chromium in terms of catalytic activity and stability. Sputtered TiN was found to be a very stable material with very low catalytic activity, a possible current collector for the cell.
Effects of Pore Shape and Oil Viscosity on the Corrosion Resistance of Oil-Impregnated Nanoporous Anodic Oxide Coating
Authors: Lee Junghoon , Choi Chang-Hwan
Published: December 2020

Oil-impregnated nanoporous anodic oxide coating improves corrosion resistance of aluminum and its alloys with a self-healing capability to physical damages in the oxide layer. However, such performances of the oil-impregnated surface degrade by the depletion of oil within the nanoporous structures. Therefore, in order to enhance the longevity and robustness, the oil should be stably immobilized in the nanopores of anodic oxide layer against external conditions (e.g., water flow or vibration). In this work, we developed a bottle-shaped pore of anodic aluminum oxide by modulating anodizing voltage and post pore-widening process. The stability of oil in the bottle-shaped nanoporous oxide layer and its corrosion resistance were compared with those of conventional cylindrical nanoporous as well as inter-connected porous structures. Moreover, the effects of oil viscosity on the corrosion resistance and self-healing capability were also investigated. The oil-impregnated bottle-shaped pore that features a smaller pore diameter at the upper layer than at the lower layer effectively inhibits the absorption of corrosive liquids in the oxide layer, thus the corrosion resistance is significantly enhanced compared to cylindrical and inter-connected porous structures. In addition, the larger diameter at the lower layer provides the advantage to retain more oil in the porous layer which can effectively flow and cover the damaged region in the oxide layer for enhanced self-healing capability to physical damages. Since the oil with a higher viscosity shows less mobility in the bottle-shaped pores, the combination of the pore geometry and the viscosity oil possibly maximizes the corrosion resistance of the nanoporous anodic aluminum oxide coating.
(Invited) Nanostructured Silicon with Incorporated Bi-Metallic Nanostructures
Authors: Rumpf Klemens , Granitzer Petra , Gonzalez-Rodriguez Roberto , Coffer Jeffery , Reissner Michael
Published: December 2020

Silicon/bi-metal nanocomposites are fabricated in using porous silicon and silicon nanotubes as templates which are filled with magnetic bi-metal nanostructures (NiCo, FePt) and the magnetic response of the different systems is investigated. The morphology such as pore diameter and inner tube diameter of the two systems are comparable. The different metals (NiCo and FePt) offer drastic differences of the magnetic properties for both, porous silicon and silicon nanotubes.

The porous silicon (PSi) is fabricated by anodizing a highly n-doped silicon wafer in aqueous hydrofluoric acid solution. By applying a current density of 90 mA/cm2 pore diameters of 60 nm in average are achieved.

The silicon nanotube (SiNTs) formation is performed by silicon deposition on a ZO wire array and finally etching off the ZO [1]. The inner diameter and the wall thickness of the tubes are dependent on the chosen fabrication parameters. For comparison the inner diameters of the SiNTs are chosen comparable to the porous silicon structure. Co as well as FePt nanoparticles are chemically grown inside the pores and the tubes, respectively. In the case of FePt the molar ratio of Fe is varied (Pt:Fe 1:1, 1:3 and 1:6).

The magnetic properties of the different composite systems are investigated. PSi and SiNTs with deposited NiCo, Co and FePt nanoparticles show significant differences whereat the FePt filled samples offer higher coercivities and higher remanence and thus a high resulting energy product. The variation of the molar ratio of the FePt deposits shows a small impact in the magnetic response for both template types. Furthermore the differences between the two template materials are figured out. Such systems consisting of hard magnetic materials within nanostructured silicon are promising for on-chip applications using three dimensional arrays of nanomagnets.

[1] X. Huang, R. Gonzalez-Rodriguez, R. Rich, Z. Gryczynski, J.L. Coffer, Chem. Comm. 49, 5760 (2013).
Luminescent Porous Silicon Filled with Nanoscopic Magnetic Structures – Assessment of the Optical and Magnetic Properties
Authors: Granitzer Petra , Rumpf Klemens , Reissner Michael , Michor Herwig
Published: December 2020

Luminescent porous silicon which is denoted as microporous silicon offers a structure size of a few nanometers. It is filled with magnetic metals resulting in a composite system with specific optical and magnetic properties. The morphology of microporous silicon offers a branched network of pores. The luminescence which is observed in the red-orange region due to the small structure size is influenced by the metal filling. The magnetic response of the samples is related to the interconnected pores and differs significantly to mesoporous silicon filled with magnetic nanostructures of similar size.

The luminescent porous silicon is etched in aqueous hydrofluoric acid solution by applying a current density of 10 mA/cm2 for 20 min resulting in a porous layer of about 0.8 µm thickness. The metal filling of microporous silicon is a challenging procedure which is carried out under cathodic conditions by pulsed electrodeposition. As electrolytes adequate metal salt solutions are used. The deposited nanosized metal structures are of the same interconnected sponge-like morphology as the template material.

Mesoporous silicon offers oriented pores whereas the diameter is in the range of 50 nm [1]. Also in this case the metal nanoparticles are electrodeposited within the matrix material.

The magnetic properties of the different systems rely on the morphology of the template material and the size and geometry of the incorporated metal deposits.

The magnetic response offers a significant difference between filled luminescent and mesoporous silicon samples. Luminescent metal filled samples show strong magnetic anisotropy between the magnetization parallel and perpendicular to the surface. For these specimens also significant differences of the anisotropy can be observed depending on the kind of deposited metal, e.g. Ni or Co. These differences are not so distinctive in the case of mesoporous metal filled silicon because of weak magnetic interactions between the metal nanoparticles.

Due to the merged optical and magnetic properties in the case of microporous silicon the nanocomposite could be promising for integrated magneto-optic devices.

[1] P. Granitzer, K. Rumpf, Semiconductor Science and Technology 31, 4004, 2016.
Welcome Remarks - C03: Pits and Pores 9: Nanomaterials - Fabrication, Properties, and Applications
Authors: Granitzer Petra
Published: December 2020

Welcome to C03: Pits and Pores 9: Nanomaterials - Fabrication, Properties, and Applications! Take a moment to listen to welcome remarks from the lead organizer, Petra Granitzer.
Towards Asymptotic Costs for Lithium-Ion Batteries
Authors: Ciez Rebecca , Chang Wesley , Steingart Daniel A.
Published: December 2020

Finding low-cost energy storage solutions is critical to minimizing the curtailment of renewable electricity generation and matching diurnal variations in electricity demand and production. Continuum electrochemical modeling has shown that minimizing cell hardware and maximizing electrode thickness for low-cost cathode materials (LMO) can help to reduce cell costs to below $100/kWh. We demonstrate the relationships between electrode thickness, porosity, rate and cost in order to design sufficiently thick intercalation cathodes that meet the minimum rate capabilities for low-cost long-duration storage applications.
Exploring Lithium Doping in the Layered Transition-Metal Oxides As Cathode Materials for Sodium-Ion Batteries
Authors: Wang Ji Eun , Jung Young Hwa , Kim Do-Kyung
Published: December 2020

Layered transition metal oxides have been one of the most promising cathode materials in the lithium-ion as well as sodium-ion batteries. In the case of sodium-ion battery configuration, several transition metals elements are electrochemically active, leading to an extensive study on the composition and structure-property relationships. Particularly, substituting elements in the layered structure is one of the effective approaches to alter the composition, structure, and electrochemical properties. The substituted element could be positioned at either transition metal site or alkali site of the layered structure and plays different role depending on the position. In this talk, I will present the substitution of lithium on different sites within the layered oxides and its effect on the electrochemical performances. Lithium was substituted at (1) alkali site of O3-type layered structure and (2) transition metal site of P2-type layered structure as cathode materials for sodium-ion batteries. The substitution sites were identified by synchrotron and neutron powder diffraction patterns. Each type was compared with transition metal oxides that do not include lithium in order to understand the role of lithium in each substitution site.
Preparation of Moth-Eye Structures By Nanoimprinting Using Anodic Porous Alumina Molds
Authors: Yanagishita Takashi , Kondo Toshiaki , Masuda Hideki
Published: December 2020

Moth-eye structures composed of an ordered array of tapered pillars have attracted increasing interest owing to their application such as displays, lenses and solar cells. A large number of methods have been reported for the preparation of moth-eye structures. Among them, nanoimprinting is a promising method for the high-throughput preparation of moth-eye structures with large sample areas. In our previous works, we have reported that an ordered anodic porous alumina can be used for a nanoimprinting mold to prepare seamless moth-eye surfaces with large sample areas [1,2]. In this process, the moth-eye structures with optimized antireflection properties was obtained by adjusting the preparation conditions of porous alumina molds. One problem currently limiting the practical use of moth-eye structures is their low durability. This problem originates from the fine, high-aspect geometrical features of moth-eye structures. Improved durability is essential for practical application of moth-eye structures as antireflection surfaces. In the present report, we describe the preparation of renewable antireflection surfaces by nanoimprinting using an anodic porous alumina mold. Renewable antireflection surfaces were formed by the lamination of polymer thin films with moth-eye structured surfaces [3]. Thin-film lamination was performed using a photocurable monomer as an adhesive. A renewed low-reflectance moth-eye structured surface could be exposed by peeling the uppermost film from the sample. Each exposed surface with moth-eye structure successfully lowered the reflection of incident light. The obtained renewable antireflection surfaces are expected to be applicable to several types of optical devices requiring high durability, such as the surface panels of displays.

T. Yanagishita, K. Nishio, and H. Masuda, Appl. Phys. Express, 2, 022001 (2009).

T. Yanagishita, T. Hidaka, M. Suzuki, and Hideki Masuda, J. Vac. Sci. Technol. B, 34, 021804 (2016).

T. Yanagishita, T. Kondo, and H. Masuda, J. Vac. Sci. Technol. B, 36, 031802 (2018).
(Invited) Formation Efficiency of Anodic Porous Alumina in Sulfuric Acid Containing Alcohol As Additives
Authors: Asoh Hidetaka , Matsumoto Mikimasa , Hashimoto Hideki
Published: December 2020

The properties of anodic porous alumina films, which are generally formed by the anodization of aluminum in an acid electrolyte, are well known to be affected by the dimensions of their structure (e.g., pore diameter, pore density, and film thickness). For instance, to increase the hardness of anodic films on aluminum, the anodization is industrially carried out at low-temperature to avoid chemical dissolution of the formed oxide film during anodization. Anodization in an electrolyte containing organic compounds is also one approach for improving the performance of anodic oxide film not only for aluminum but also for other light metals such as titanium and magnesium (1).

One such initiative is anodization of aluminum at a relatively high current density or high voltage using a common acidic electrolyte (e.g., sulfuric acid, oxalic acid, or phosphoric acid) with an alcohol added. In such studies, the effects of adding an alcohol are summarized as follows: i) the alcohol functions as an anti-freeze agent in the electrolyte, enabling the anodization temperature to be lowered; ii) the alcohol acts as a cooling agent—specifically, the vaporization of alcohol at the bottom of the pore channels removes the heat generated at the aluminum/oxide interface; and iii) nonuniform growth of the anodic film (i.e., burning) is effectively prevented, even during high-field anodization. However, these effects are observed not only for monohydric alcohols with a boiling point less than 100 °C (e.g., methanol and ethanol) but also for polyhydric alcohols with a boiling point greater than 100 °C (e.g., ethylene glycol and glycerol). Therefore, the effect of alcohol addition cannot be reasonably explained solely on basis of the boiling point of the alcohol used as an additive. Understanding the effects of alcohol addition necessitates a systematic investigation comparing types of alcohols, in addition to further fundamental studies.

In this study, monohydric alcohols or polyhydric alcohols were added to the sulfuric-acid-based electrolyte to examine their effects on the anodization behavior of aluminum, the coating ratio, the porosity, the maximum attainable film thickness, and the resulting etching ability. Anodization was conducted in sulfuric acid solutions containing various alcohols with different physical properties under mild anodization conditions with a constant current of 100 A·m−2 at 20 °C (2, 3). The influence of the type and concentration of alcohol on the coulombic efficiency of film formation and the structure of the porous alumina under a constant electric charge was also investigated. In terms of basic research, the potential impact of alcohol addition in electrolytes will be discussed.

H. Asoh, K. Asakura, H. Hashimoto, RSC Advances, 10, 9026-9036 (2020).

H. Asoh, M. Matsumoto, H. Hashimoto, Surface and Coatings Technology, 378, 124947 (2019).

M. Matsumoto, H. Hashimoto, H. Asoh, Journal of The Electrochemical Society, 167, 041504 (2020).
Fabrication of Sticky and Slippery Superhydrophobic Aluminum Surfaces Covered with Nanostructured Anodic Oxide
Authors: Kikuchi Tatsuya , Kondo Ryunosuke , Suzuki Ryosuke O. , Natsui Shungo , Nakajima Daiki
Published: December 2020

Anodizing aluminum in a concentrated pyrophosphoric acid solution leads to the formation of numerous anodic alumina nanofibers, and this nanofiber-covered surface shows superhydrophilicity measuring less than 10° in water contact angle. In contrast, as the alumina surface is modified with a self-assembled monolayer (SAM), the surface exhibits superhydrophobicity measuring more than 150°. Herein, we demonstrate the fabrication of sticky and slippery superhydrophobic aluminum surfaces by optimizing the nanostructure of anodic alumina nanofibers.

Commercially available 5N aluminum and 3004 aluminum alloy were anodized at a constant voltage of 75 V for up to 60 min for the formation of anodic alumina nanofibers on the surface. The specimens, then, were immersed in a 1.5 mM 3,3,4,4,5,5,6,6,7,7,8,8,8,-tridecafluorooctylphosphonic acid (FOPA)/ethanol solution at 313 K for 48 h to form SAMs on the surface of the anodic oxide. The sliding behavior of the water droplet formed on the anodized surface was examined by advancing and receding contact angle investigations.

Numerous anodic alumina nanofibers and nanofiber-tangled intermetallic particles were formed on the aluminum surface by anodizing in pyrophosphoric acid. As the nanofiber-covered aluminum alloys were modified with fluorinated phosphonic acid SAMs, the aluminum surface exhibits a superhydrophobic behavior with contact angles of more than 170°. The sliding behavior of the water droplet was drastically changed with the anodizing time, and the highly sticky and slippery aluminum surfaces could be fabricated by controlling the structure of alumina nanofibers (Figure 1). A superhydrophobic aluminum surface with different wettabilities including sticky and slippery properties was fabricated by the selective anodizing process.

Figure 1
Numerical Simulation of Tribocorrosion of Titanium with Galvanic Couple in Simulated Body Fluid
Authors: Miyabe Sayaka , Fujii Norifumi , Fujimoto Shinji
Published: December 2020

Titanium and its alloys are widely used for metallic surgical implants, such as artificial hip joints and bone plate. The artificial hip joints have galvanic couple between stem made of Titanium or its alloy and femoral head made of CoCr alloy, and are subjected to high levels of mechanical stress. Tribocorrosion of artificial hip joints has been frequently reported. The tribocorrosion behavior is affected not only by anodic reaction on friction part but also by cathodic reaction on the non-friction part. Therefore, it is important to study the effect of cathodic reaction on tribocorrosion. However, it is difficult to analyze local reaction and separate the anode current and cathode current by experiments. Since the numerical simulation enables such analysis, it is very useful to apply the numerical simulation to the analysis of tribocorrosion. However, the electrochemical numerical simulation of tribocorrosion has not been performed yet. In the present work, we performed the electrochemical numerical simulation for tribocorrosion of Titanium with galvanic couple in simulated body fluid to investigate the effect of the cathodic reaction on the tribocorrosion behavior.
Investigation of Li+ Insertion in NMC622 Cathode Material upon Deep Lithiation Via Electrochemistry and x-Ray Absorption Spectroscopy
Authors: Usubelli Camille , Besli Muenir Mustafa , Kuppan Saravanan , Metzger Michael , Christensen Jake , Gorlin Yelena
Published: December 2020

Nickel-based cathode materials have become an exciting alternative to the widely used LixCoO2 (LCO) for consumer electronics. The main advantages of this type of cathode materials over the LCO electrodes are a higher practical capacity and excellent safety characteristics.[1] Additionally, the tendency to increase the nickel content of these electrodes proves to be cost effective due to their lower cobalt content.[2] One known drawback of nickel-containing layered cathodes is their poor first cycle efficiency of 87-88.6% when cycled in the standard potential window of 2.8 V to 4.4V, whereas LCO cathodes reach a first cycle efficiency of 98%.[3]

In this study, we focus on the electrochemical properties of LixNi0.6Mn0.2Co0.2O2 (NMC622) cathode materials. We start by demonstrating that it is possible to recover the capacity “lost” by the NMC622 electrode in the first cycle by increasing the applied overpotential, as was previously shown for other nickel-based cathodes, including LiNiO2, LiNi1/3Mn1/3Co1/3O2, and LiNi0.8Co0.10Al0.05O2.[3-4] We then establish through electrochemical measurements that it is possible to overlithiate the NMC622 cathode material by as much as 300 mAh/g relative to the pristine electrode. Finally, we complement our electrochemical characterization with ex-situ X-ray diffraction as well as soft and hard X-ray absorption spectroscopy experiments, to elucidate how the structure of the material and the oxidation states of the transition metals (nickel, cobalt, manganese) change throughout the overlithiation process.

[1] Andre, D. et al. Future generations of cathode materials: An automotive industry perspective. J. Mater. Chem. A
3, 6709–6732 (2015).

[2] Xu, J., Lin, F., Doeff, M. M. & Tong, W. A review of Ni-based layered oxides for rechargeable Li-ion batteries. J. Mater. Chem. A
5, 874–901 (2017).

[3] Kang, S. H., Yoon, W. S., Nam, K. W., Yang, X. Q. & Abraham, D. P. Investigating the first-cycle irreversibility of lithium metal oxide cathodes for Li batteries. J. Mater. Sci.
43, 4701–4706 (2008).

[4] Dahn, J. R., von Sacken, U. & Michal, C. A. Structure and electrochemistry of Li1+/-xNiOz and a new Li2Ni02 phase with the Ni (OH) 2 structure. Solid State Ionics
44, 87–97 (1990).
Improving the Energy Density of Ni-Rich Layered Cathodes: Through Increasing Nickel Composition or By Raising the Charge Cut-Off Voltage?
Authors: Park Geontae , Nam Gyeong Won , Sun Yang-Kook
Published: December 2020

Since the commercialization of lithium-ion batteries, portable energy storage devices have undergone extensive development. This has allowed for the significant extension of their application areas especially large-scale applications such as plug-in hybrid electric vehicles and electric vehicles (EVs). However, the limited driving range, high costs, and safety concerns of electrified transportation systems are impeding their wider acceptance by society.1 Therefore, further improvements in the energy density, thermal stability, and cycle life of LIBs are necessary to accelerate their penetration into the automobile market.

Generally, two approaches can be undertaken to enhance the energy density of NCM cathodes. The first approach is improving the specific capacity of the cathodes by increasing the composition of the redox-active nickel metal relative to other transition metals.2 This transition towards higher Ni produced positive effects in terms of energy density. However, it inevitably led to the deterioration of the cycling and thermal stability of the materials. The second approach is increasing the upper cut-off voltage to extract more Li+ ions. Enhancing the energy density of NCM-111 and NCM-523 has been investigated by operating at charge cut-off potentials higher than 4.3 V.3, 4 However, there is no report directly comparing electrochemical, structural, and thermal properties of the cathodes which are currently used (NCM-622) and will be adapted (NCM-811 and NCM-90) for EVs.

In this study, the two approaches, increasing the Ni contents and the upper cut-off potential for high energy density, are directly compared. The comparative study is specifically carried out in terms of capacity and cycling lifespan as well as thermal stability.

References

S.-T. Myung, F. Maglia, K.-J. Park, C. S. Yoon, P. Lamp, S.-J. Kim and Y.-K Sun., ACS Energy Lett., 2017, 2, 196.

H.-J. Noh, S. Youn, C. S. Yoon and Y.-K. Sun, J. Power Sources, 2013, 233, 121.

J. Kasnatscheew, M. Evertz, B. Streipert, R. Wagner, S. Nowak, I. C. Laskovic and M. Winter, J. Phys. Chem. C, 2017, 121, 1521.

J. A. Gilbert, J. Bareno, T. Spila, S. E. Trask, D. J. Miller, B. Z. Polzin, A. N. Jansen and D. P. Abraham, J. Electrochem. Soc., 2017, 164, A6054.
Resolving Li-F Locking Effect in Disordered Rocksalt Cathodes with Mg-Doping
Authors: Zhong Peichen , Cai Zijian , Zhang Yaqian , Ouyang Bin , Zeng Guobo , Chen Yu , Lun Zhengyan , Ceder Gerbrand
Published: December 2020

The discovery of Li-excess cation-disordered rocksalt (DRX) cathodes greatly enlarges the design space beyond the layered NCM-type rocksalt chemistries. Fluorination of DRX cathodes can provide more capacity by reducing the transition metal valence and reduce oxygen loss by protecting the surface. On the other hand, fluorine’s strong bonding with lithium creates Li-F short-range order (SRO) and prevents some lithium from being extracted. We performed a systematic computational study to investigate which inactive doping elements can lower the bonding strength with lithium, and found that substituting a small amount of Li by Mg could be beneficial for generating higher capacity.

To investigate this effect, we synthesized two composition with identical Li-excess, fluorination and transition metal amount: Li1.25Mn0.45Ti0.3O1.8F0.2 (LMTF) / Li1.25Mg0.1Mn0.45Nb0.2O1.8F0.2 (LMMNF). Electrochemical experiment confirmed an increased capacity from 279 mAh/g (899 Wh/kg) for the undoped sample to 290 mAh/g (905 Wh/kg) for the Mg-doped sample. The inaccessible Li-content after the first cycle reduces from 0.17 to 0.24 per formula unit. In a related group of composition Li1.33Mn0.67O1.33F0.67 (LMF) and Li1.28Mg0.11Mn0.61O1.33F0.67 (LMMF) the inaccessible Li-ion content was reduced from 0.53 to 0.47 per formula unit, while delivering a similar charge capacity 276 mAh/g and 272 mAh/g.

By comparing these results with detailed Monte Carlo simulations of the ionic configurations in the material we conclude that the Li-site distribution plays a more important role than the metal-redox capacity in determining the initial capacity. While fluorination enhances the long-term performance of DRX materials its strong attraction to lithium can make some of those Li-ions unextractable in a reasonable voltage window. Mg-doping can be used to free some of these locked Li-ions within the working voltage range, thus delivering higher charge capacity. This new design strategy should be considered in oxyfluorides cathode materials.

Figure 1
Uniform Carbon Coated Na3V2(PO4)2O2xF3
−
2x Nanoparticles for Sodium Ion Batteries as Cathode
Authors: Park Sohyun , Soundharrajan Vaiyapuri , Park Sunhyeon , Kim Jaekook
Published: December 2020

A uniform carbon-coated Na3V2(PO4)2O2xF3
−
2x (NVPOF/C) nanoparticle synthesized by a novel pyro synthesis method is utilized for sodium-ion batteries (SIBs) as a cathode. Remarkably, the electrochemical properties are performed at high rates show significantly improved discharge capacity (Fig. 1). At 0.1 C, the NVPOF/C cathode shows a discharge capacity of 130 mAh g−
1, corresponding to 100% of the theoretical capacity. Even at 50 C, a discharge capacity of ~85 mAh g−
1 could be attained. The in situ X-ray diffraction and ex-situ synchrotron X-ray absorption near edge structure spectroscopy results exposed that the reversible sodium ion insertion/ extraction into/from NVPOF/C host structure occurs with a small volume change (3.4%), indicating the structural stability of the cathode. Our study validates that the Na3V2(PO4)2O2xF3
−
2x/C electrode is a promising candidate for developing high power/ energy density cathodes for SIBs.

Figure 1. (a) Galvanostatic charge/discharge potential profiles of Na3V2(PO4)2O2xF3-2x in the potential range of 2.0 ~ 4.3V at 0.1C. (b) Cycle performance at 1C. (c) The discharge profiles of different C. (d) Comparison of the rate capabilities at various curve

Figure 1
Investigating Magnesium Ion Intercalation in WS2 Cathodes
Authors: Houghton Todd , Nandy Mayukh , Modi Arjun , Swaminathan Srivatsan , Yu Hongbin
Published: December 2020

Due to an unmatched combination of energy density, power output, and charge/discharge stability, lithium-ion batteries remain the energy storage technology of choice for a diverse and growing ecosystem of electronic devices, from mobile phones to electric vehicles. However, as the number of applications continues to rise, limitations of Li-ion concerning achievable capacity, cost, and environmental pollution have become increasingly apparent. Divalent Mg-ion chemistries present an intriguing alternative to lithium; however, studies of sulfur-containing chalcogenide cathodes reveal no clear path to commercial adoption. MoS2 and Chevrel-type cathodes do not currently meet anticipated energy density targets, while TiS2, Ti2S4, and Chevrel compounds use volatile electrolyte solutions.

While exhibiting an atomic structure and interlayer spacing similar to TiS2 and MoS2, the electrochemical properties of WS2 cathodes remain largely unexplored in the context of Mg-ion intercalation. Here, we study a magnesium ion half-cell constructed from mechanically flexible materials, chosen for their low cost, simple fabrication steps, and separator-free reaction chemistry. Cathodes were fabricated from WS2 powder and electrolyte binder, while a polymer-based electrolyte made of PVDF-HFP and magnesium perchlorate dissolved in ethylene carbonate/propylene carbonate was chosen for its high ionic conductivity and low volatility. Analysis using cyclic voltammetry shows a reversible redox reaction involving Mg species at the cathode/electrolyte interface, indicating presence of an intercalation reaction. Additional cathode surface data is provided by XPS, Powder XRD, and Raman spectroscopy. Cell fabrication details and analysis of reacted cathodes in the context of Mg intercalation will be discussed.