bluuebunny/crossref_metadata_2025 huggingface dataset:
Liver dysfunction in COVID-19: a useful prognostic marker of severe disease?
Authors: Lok James , Gess Markus
Published: December 2020

Background

COVID-19 is a global pandemic caused by the novel coronavirus SARS-CoV-2. Risk factors and prognostic markers of severe disease remain to be fully determined, although some studies have suggested a correlation between abnormal liver function and adverse outcomes. Further studies are needed to investigate this further.

Methods

This retrospective study enrolled patients with a confirmed diagnosis of COVID-19 who were admitted to Kingston Hospital in the UK. Data collected included age, sex, ethnicity, comorbidity profile, biochemical markers of liver function and the acute phase response, and overall outcome.

Results

Between 16 March 2020 and 30 April 2020, a total of 343 patients were admitted to the acute medical team at Kingston Hospital. Excluding those with a history of liver disease, 299 patients had liver function tests performed with abnormalities demonstrated in 44.8% of individuals. Derangement of liver function was associated with greater need for ventilatory support (p<0.001), admission to high dependency unit or intensive care (p<0.001) and increased length of hospital stay (p<0.001). Of note, liver dysfunction was more common in those of non-white ethnicity (p=0.007) and correlated with higher levels of C reactive protein (p=0.01) and ferritin (p<0.001).

Conclusion

Abnormal liver function is associated with a negative outcome among those hospitalised with COVID-19. The cause for this association is unclear, but correlation between abnormal liver function and higher serum levels of acute phase proteins suggest that dysregulation of the immune system in response to SARS-CoV-2 may be contributory.
Dietary beliefs and recommendations in inflammatory bowel disease: a national survey of healthcare professionals in the UK
Authors: Crooks Benjamin , McLaughlin John , Limdi Jimmy
Published: December 2020

Background

The role of diet in inflammatory bowel disease (IBD) remains incompletely understood. Knowledge around the actual dietary advice healthcare professionals provide to individuals with IBD is scarce. Our objective was to describe the dietary beliefs of healthcare professionals and dietary recommendations made to people with IBD.

Methodology

An online survey regarding IBD-related dietary beliefs and advice provided to patients was distributed to gastroenterologists, dietitians and IBD nurses in the UK.

Results

Two-hundred and twenty-three eligible healthcare professionals participated: 107 (48%) believed that diet was involved in IBD development. The most frequently implicated dietary components were processed foods (78%), additives/preservatives (71%), sweet/sugary foods (36%), red meat (36%) and fatty foods (31%). Views were broadly consistent across professions, however, gastroenterologists were significantly more likely to believe red meat and additives/preservatives initiated IBD. One hundred and thirteen participants (53%) believed that diet could trigger disease relapse and 128 (61%) recommended limiting specific foodstuffs to reduce this risk, most commonly high fibre foods. Forty-six (23%) considered recommending a low Fermentable Oligo-, Di- and Monosaccharides and Polyols diet to reduce relapse risk. IBD nurses and healthcare professionals with <5 years experience were most likely to recommend this. Dietitians felt most comfortable providing dietary advice for functional gastrointestinal symptoms in quiescent IBD.

Conclusion

Dietary advice in IBD is inconsistent reflecting uncertainty among healthcare professionals. While some consensus exists regarding dietary components implicated in IBD development and relapse, dietary recommendations varied. Future research is required to disentangle these complex relationships, alongside better training and education.
Swept source intraoperative OCT angiography
Authors: Zhang Ziyi , Zhu Tiepei , Cao Tongtong , Gong Zhaoyu , Yao Lin , Liu Kaiyuan , Ye Juan , Li Peng
Published: December 2020

To accurately guide surgical instruments during ophthalmic procedures, some necessary intraoperative depth perception is required, which standard surgical microscopes supply limitedly. Intraoperative optical coherence tomography (iOCT), combining optical coherence tomography (OCT) technology and surgical microscope, enables noninvasive, real-time and high-resolution cross-sectional imaging. Currently, though iOCT enables structural imaging, little research has been done on intraoperative angiography. In this work, we presented a swept-source intraoperative OCT angiography (SS-iOCTA) system based on a standard surgical microscope, which provides both structural and angiographic images. The feasibility of the proposed SS-iOCTA was confirmed through deep anterior lamellar keratoplasty (DALK) of ex vivo porcine eyes and blood perfusion imaging of in vivo rat cortex. High-resolution intraoperative feedback, including sub-surface structure and angiogram of biological tissue, can be visualized simultaneously with the SS-iOCTA system, which expand the surgeon’s capabilities and could be widely used in clinical surgery.
Mitigating Data-only Attacks by Protecting Memory-resident Sensitive Data
Authors: Palit Tapti , Monrose Fabian , Polychronakis Michalis
Published: December 2020

Gaining reliable arbitrary code execution through the exploitation of memory corruption vulnerabilities is becoming increasingly more difficult in the face of modern exploit mitigations. Facing this challenge, adversaries have started shifting their attention to data leakage attacks, which can lead to equally damaging outcomes, such as the disclosure of private keys or other sensitive data.

In this work, we present a compiler-level defense against data leakage attacks for user-space applications. Our approach strikes a balance between the manual effort required to protect sensitive application data, and the performance overhead of achieving strong data confidentiality. To that end, we require developers to simply annotate those variables holding sensitive data, after which our framework automatically transforms only the
fraction
of the entire program code that is related to sensitive data operations. We implemented this approach by extending the LLVM compiler, and used it to protect memory-resident private keys in the MbedTLS server, ssh-agent, and a Libsodium-based file signing program, as well as user passwords for Lighttpd and Memcached. Our results demonstrate the feasibility and practicality of our technique: a modest runtime overhead (e.g., 13% throughput reduction for MbedTLS) that is on par with, or better than, existing state-of-the-art memory safety approaches for selective data protection.
Influenza Virus: Tracking, Predicting, and Forecasting
Authors: Ali Sheikh Taslim , Cowling Benjamin J.
Published: December 2020

Influenza is a common respiratory infection that causes considerable morbidity and mortality worldwide each year. In recent years, along with the improvement in computational resources, there have been a number of important developments in the science of influenza surveillance and forecasting. Influenza surveillance systems have been improved by synthesizing multiple sources of information. Influenza forecasting has developed into an active field, with annual challenges in the United States that have stimulated improved methodologies. Work continues on the optimal approaches to assimilating surveillance data and information on relevant driving factors to improve estimates of the current situation (nowcasting) and to forecast future dynamics.
From the Editor: Competing (Collaborating?) in the Science & Technology Space
Authors: Rajeshwar Krishnan
Published: December 2020

The dog days of summer are sputtering to a close (at least in the northern hemisphere) and soon fall will be upon us, when this issue of Interface will reach your hands. Incidentally, a scientist’s curiosity drove me to seek an explanation for the term “dog days.”
From the Editor: Light Up My Life
Authors: Rajeshwar Krishnan
Published: December 2020

This particular issue of Interface is all about lighting and features the ECS Luminescence and Display Materials (LDM) Division.
Pennington Corner: Tienes que Complir
Authors: Calvo Roque J.
Published: December 2020

On February 21, 2009, I attended the dedication of Carril Court at Princeton University to honor the great Hall-of-Fame basketball coach Peter Carril. He has been an influential force in my life, and to see him reluctantly accept this honor brings a rush of inspiration and awareness of the importance of the message in this column.
From the President: Winds of Change
Authors: Natishan Paul M.
Published: December 2020

After our meeting in Vienna, I stayed for a few days to enjoy the city. I was sitting at a streetside café enjoying a cup of coffee and a wonderful torte; the winds were picking up, ushering in a change in the weather. As I sat, I thought about the meeting and how much has changed in the Society since I became a member 28 years ago.
JES Classics: ECS Science at Its Best: Phospho-Olivine Cathodes for Lithium-Ion Batteries
Authors: Manthiram Arumugam
Published: December 2020

Lithium ion batteries have revolutionized the portable electronics market and are being intensively pursued for hybrid electric vehicle (HEV) and plug-in hybrid electric vehicle (PHEV) applications.
Organic Light Emitting Devices for Lighting
Authors: Shiang Joseph J.
Published: December 2020

Lighting is one of the oldest electronics industries, and has been characterized throughout its history by its adoption and extension of new technologies. Most recently, solid state lighting (SSL) sources have become available and have the potential to offer better energy efficiency than any other lighting technology.
From Laboratory Breakthrough to Technological Realization: The Development Path for Solid Acid Fuel Cells
Authors: Boysen Dane A. , Cha Sukyal , Chisholm Calum R.I. , Giapis Konstantinos P. , Haile Sossina M. , Papandrew Alexander B. , Sasaki Kenji A.
Published: December 2020

Open up any textbook on fuel cells and the reader finds a list of five classic types of fuel cells, each differentiated by the nature of the electrolyte: polymer electrolyte membrane (or sometimes proton exchange membrane), phosphoric acid, alkali, molten carbonate, and solid oxide.
JES Classics: ECS Science at Its Best: Impact of Kiukkola-Wagner Paper on the Development of Electrochemical Probes and Tools for Fundamental Studies and Industrial Applications
Authors: Fergus Jeffrey W. , Gopalan Srikanth , Gur Turgut , Mukundan Rangachary , Weppner Werner J. F.
Published: December 2020

The 1957 paper, “Measurements on Galvanic Cells Involving Solid Electrolytes” by Kiukkola and Wagner is just one example of the many fundamental scientific contributions made by Carl Wagner. Although Wagner is known for such fundamental contributions, he had, in fact, always looked at practical problems and needs.
Modeling Corrosion in Lead-Acid Cell and Parameter Extraction from Lithium-Ion Cells
Authors: Boovaragavan Vijayasekaran
Published: December 2020

2008 ECS Oronzio de Nora Industrial Electrochemistry Fellowship Report
High Precision Charger to Investigate Spinel Li1+xMn2-xO4 at Elevated Temperatures
Authors: Chou Shulei
Published: December 2020

2009 Edward G. Weston Summer Research Fellowship — Summary Report
Improving Flow-through Electrode Performance Using Computational Design of Architected Porosity
Authors: Beck Victor A , Watts Seth E , Wong Jonathan M , Tortorelli Dan A , Baker Sarah E , Duoss Eric B , Worsley Marcus A.
Published: December 2020

Electrochemical systems such as fuel cells, flow batteries, and electrochemical reactors are prevalent in industry, but few tools for their numerical design and optimization exist. Controlling fluid flow, active species distribution, and mass transport in the electrode has a dramatic impact on power and efficiency. However, this control is often limited to changing a quasi-two-dimensional flowfield and selecting bulk properties of a monolithic porous material electrode like carbon felt or paper. This can lead to non-uniform reaction rates, underutilized regions of the flow cell, and can limit the ultimate performance of the devices. To address these limitations, we propose using electrodes composed of a micro-architected variable porosity medium. As a specific example, we enable variable porosity by leveraging advances in the additive manufacture of microscale iso-truss lattices. We employ physics-based homogenization of the governing microscopic, continuum transport equations to develop a descriptive model and enable the design of this variable porosity electrode. Our tool is used to generate optimized architectures which are predicted to outperform monolithic electrodes when used in a standard flow-through configuration. We conclude by demonstrating how the optimal porosity distribution changes to retain the performance benefits as the electrode is scaled beyond benchtop-experiments

LLNL-ABS- 810799

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Lithium Ion Battery Life Analysis in Railway Application
Authors: Hyun Jung Eun
Published: December 2020

It is well-known that the life of battery is influenced by the temperature, current rate/ pattern, depth of discharge, and chemistry of cell. Capacity and power fade over cycling and storage of lithium ion batteries are still major barriers as their calendar life is 3-5 years whereas target automotive and stationary applications require 10-20years of life time. Battery lifetime is highly dependent on application conditions. In railway application the power pattern is usually similar and repeated, and needs at least 5 years-life warrant. Understanding the relationship between the operating conditions and aging behavior of the batteries is an important task to increase the lifespan. However, it is not easy to quantify the effect of each condition on aging behavior as the aging of batteries involves multiple closely interrelated factors. Accelerated degradation testing with associated modeling and data analysis can effectively be used to predict failure-time distributions. The behaviors of lithium ion cells and aging mechanisms are strongly dependent to the battery cell chemistry and technology so should be chosen in the right application. The lithium ion battery in railway is operated during the whole day time in the mainly outside, and needs high power, high energy characteristics like PHEV and should store the regenerative breaking energy from the traction driving motor.

In this study by using an accelerated method the life of railway application battery is evaluated. This study attempts to quantify the strength of the stress factors and the relationship between aging behavior and operating conditions. The accelerating factor is a temperature and depth of discharge, current pattern to understand the effect on life.
Electrochemical Pressure Impedance Spectroscopy As a Diagnostic Method for Hydrogen-Air Polymer Electrolyte Fuel Cells
Authors: Zhang Qingxin , Eikerling Michael H , Gates Byron D.
Published: December 2020

This work introduces a novel in-situ diagnostic method for polymer electrolyte fuel cells (PEFCs) referred to as electrochemical pressure impedance spectroscopy (EPIS). Inspired by electrochemical impedance spectroscopy (EIS), EPIS is a spectroscopic technique that analyses correlations between frequencies in an applied pressure signal and the corresponding voltage response signal in the frequency domain. In EPIS, cathode cell pressure is modulated as a sinusoidal wave by the back-pressure controller (BPC), and the cell voltage is monitored as the response signal. Cell voltage response originates from the membrane electrode assembly (MEA) and, therefore, EPIS can be used to probe cathode transport properties and is sought to develop tools that can be used to study water transport as a function of changes in structure and operating conditions. The cathode reactant gas flows through channels with a pressure drop and, thus, the pressure signal is not identical in different sections of the flow channel. Before studying the relationships between pressure and voltage, it is important to consider the impact of the flow channel on oscillations in the pressure response. The response of the system as a function of correlations between the cathode inlet pressure and the cathode outlet pressure is examined in this work to probe the contributions of the flow channel. Due to instrumental limitations, the BPC can only perform tests at a frequency of 0.1 Hz. Experimental limitations like cathode stoichiometry ratio, cathode flow rate, oxygen partial pressure at cathode, and pressure oscillation amplitude are intensively studied, and therefore, EPIS experimental formalism is defined in this work.

Figure 1
State of Charge Estimation Method for Lithium-Ion Batteries Using Machine Learning Considering Thermal Variation
Authors: Takahashi Kazuki , Miao Shan , Katayama Noboru
Published: December 2020

Lithium-ion Batteries are now widely used and very useful. However, it is difficult to accurately estimate the state of charge (SoC) of a Lithium-ion Battery in use. Possible causes include the effects of temperature, charge/discharge cycles, and degradation. The conventional method uses the Electrochemical Impedance Spectroscopy to estimate the SoC by fitting the equivalent circuit model of the lithium-ion battery used. This method has the disadvantage of making the equivalent circuit model more complex and computationally intensive in order to accurately represent the battery. Therefore, we propose a new SoC estimation method based on machine learning. In this study, Lithium-ion Batteries were placed in a thermostatic chamber between 0°C and 20°C, and the impedance at each temperature was measured using the Electrochemical Impedance Spectroscopy while charging and discharging repeatedly. The input layer was set to the measured impedance and the output layer to the SoC, and the estimation was performed using a neural network. Grid search was used to optimize the hyperparameters and to reduce the errors. As a result, the error was 4.174 % when the temperature was 20 ℃. Considering the temperature characteristics of the Lithium-ion Battery, the error was 4.220 % when the temperature range was changed from 0 ℃ to 20 ℃. The proposed method, a neural network, can be used to estimate the SoC even under the temperature change.
Morphological Evolution in Rechargeable Alkaline Zinc Anodes
Authors: Chen Qing , Zhu Guoyin
Published: December 2020

Dendrites, passivation, and shape changes are the common suspects to blame in the failures of rechargeable zinc anodes. The formation of porous zinc is not, or rarely discussed in the context of zinc batteries. We show that when starting with an electrode made of ZnO powder, the charging and then discharging cycles to a certain depth will make it partially a porous zinc electrode. This morphological evolution has important implications to the structural stability, as it reshapes the electronic conductivity, the specific area, the structural uniformity, and the geometrical path of the electrochemical reactions. By carefully dissecting some forty coin cells, we show step by step how the morphological evolution takes place and progresses, and how it may affect the cycle life.
Data-Driven Synthesis Optimization of Cathode Materials
Authors: Liow chi Hao , Hong Seungbum , Na Moony , Bang Kihoon , Lee Hyuck Mo , Byon Hye Ryung , Shim Yoonsu , Yuk Jong Min , Baucour Arthur , Shin Jonghwa , Cho EunAe , Lee Yongju , Kang Hyeonmuk , Cho Seongwoo , Park Gun , Yeom Jiwon
Published: December 2020

Machine intelligence-based optimizing synthesis parameters offers exciting opportunities in various domain of materials chemistry where large and comprehensive dataset are available. Aiming to construct a “design-to-device” pipeline for battery application with small discrepancy, we adapt machine learning model based on actual experimental data from curated literatures to predict the discharge capacity of Nickel-Manganese-Cobalt (NCM) cathode material. However, missing data is an inherent problem from the results based on literature. Herein we introduce imputation techniques to fill the missing data based. To this end, we show that our model have remarkable predictive capability with the average coefficient of determinant, R2 = 0.84 for training sets. In addition, we also validate our model prediction by the experiments, which yields in less than 8% error. The present work highlights a promising data driven materials synthesis approach, which underpins nonlinear structure-properties relationship for broad range of materials development.
Low Thermal Boundary Resistance in Direct Wafer Bonded GaN|Si Hetereojunction Interfaces
Authors: Huynh Kenny , Liao Michael Evan , Bai Tingyu , Wang Yekan , Dragoi Viorel , Razek Nasser , Guiot Eric , Caulmilone Raphael , Yates Luke , Graham Samuel , Goorsky Mark S.
Published: December 2020

In this study, thermal and structural characteristics of direct wafer bonded (0001) GaN on (001) Si were examined as a continuation of a previous effort1. EVG® ComBond® equipment was used for bonding under high vacuum (~10-8 mtorr) at room temperature by bombarding the GaN and Si surfaces with an Ar ion beam to remove unwanted native surface oxides.1,2 The samples are placed face-to-face and pressure is applied to initiate the bond. The [1010] GaN edge was aligned parallel to the Si [110] edge. An X-ray diffraction reciprocal space map of the (004) Si and (0004) GaN revealed that there is a ~0.2° tilt between the GaN and Si layers. Bombardment of the bonded surface causes an amorphous region at the interface that has been seen in many other bonded systems.3-5 High resolution transmission electron microscopy revealed a ~2 nm amorphous region at the bonded interface, which resides mostly in the Si as confirmed by energy dispersive x-ray spectroscopy. This is consistent with SRIM6 simulations that predict a shallower damage profile in GaN as compared to Si. The thermal boundary resistance of the GaN|Si interface was measured to be 3.9 m2K/GW,1 an interfacial thermal resistance lower than any of the current state-of-the-art GaN-based heterojunctions, including GaN|Si,3 GaN|SiC,4 and GaN|diamond.5 Subsequent annealing is expected to alter the thermal properties as the bonded interface is allowed to recrystallize10. The intermediate steps of the recrystallization at the bonded interface were examined using TEM to give insight on the interface recovery and reconfiguration mechanism of this ion bombarded GaN|Si interface.

Dragoi, et al., ECS Trans., 86(5), 23 (2018)

Flötgen, et al., ECS Trans., 64(5), 103 (2014)

E. Liao, et al., ECS Trans., 86(5), 55 (2018)

Xu, et al., Ceramics International, 45, 6552 (2019)

Mu, et al., Appl. Surf. Sci., 416, 1007 (2017)

F. Ziegler, et al., The Stopping and Range of Ions in Solids vol 1 (Oxford, Pergamon), (1985)

Yates, et al., ASME InterPACK (2015)

Cho, et al., Phys. Rev. B, 89, 115301 (2014)

Sun, et al., APL, 106(11), 111906 (2015)

Mu, F. et al., (2019). ACS applied materials & interfaces, 11(36), 33428-33434.

Figure 1
Ion Species Dependence on the Interfacial Properties of Silicon Homojunctions Bonded Using an Ion Bombardment Treatment
Authors: Liao Michael Evan , Huynh Kenny , Bai Tingyu , Flötgen Christoph , Goorsky Mark S.
Published: December 2020

Surfaces of (001) p-type silicon substrates were bombarded with either Ar or Kr ions prior to direct wafer bonding using an EVG© ComBond© high-vacuum wafer-bonding system.1 Previously, we showed that this ion bombardment treatment induces a thin ~nm amorphous region at the bonded interface.2 In this study, we extend upon this previous effort towards a fundamental understanding of this amorphous interfacial region by examining the dependence of the bonded interface’s properties with two different ion species. The ion energies used spanned from a factor of 0.5 to 2.5 times of a baseline energy E0. X-ray reflectivity measurements were performed on single unbonded wafers that were ion bombarded with either Ar or Kr to determine the thickness of the amorphous region as well as its mass density compared to bulk Si. Wafers treated with Ar showed no surface mass density dependence with ion energy, while wafers treated with Kr did show an ion energy dependence. While the Ar treatment reduces the surface density to ~80% of bulk Si density regardless of the energy used, the Kr treatment reduces the surface density to as low as ~70% of bulk Si density at 2.5⋅E0. Furthermore, for a given energy, the Ar treatment resulted in thicker layers than the Kr treatments, which is consistent with SRIM3 simulations because Kr is a heavier species than Ar. Current-voltage measurements were also used to probe the electrical properties of the bonded interfaces. Band structure modeling of the current-voltage measurements revealed that the amorphous region can be modeled with a step barrier that spans the thickness of the amorphous region.

References

Flötgen, et al., ECS Trans., 64(5), 103 (2014).

E. Liao, et al., ECS Trans., 86(5), 55 (2018).

F. Ziegler, et al., The Stopping Range of Ions in Solids vol. 1, (1985).

Figure 1
Direct Wafer Bonding Methods: A Practical Process Selection Guide
Authors: Dragoi Viorel , Rebhan Bernhard , Pabo Eric
Published: December 2020

The development of various low temperature wafer bonding methods in early 2000’s marked an important milestone for the direct wafer bonding applications. Wafer bonding was adopted in the microelectronics fabs as the use of plasma activated wafer bonding allowed for meeting the CMOS manufacturing requirements in terms of contamination control as well as thermal budget limitations (less than 400°C).

A wafer bonding technique reported in the literature already in late 80’s – early 90’s allowed even for room temperature bonding of some materials but despite this important feature it remained mainly at the fundamental research level, with not so numerous applications in semiconductor industry. This technique is known mainly as “surface activated bonding”, “SAB” or “room temperature covalent bonding”. Over the past decade, the interest in surface activated bonding increased significantly as excellent results were reported particularly for compound semiconductors applications (e.g. solar cells manufacturing, power devices, etc.). With three types of direct wafer bonding processes, high, low and room temperature, sometimes people are facing issues in selecting the proper wafer bonding process. Our goal in this presentation is to introduce the specific features of each technique and present their benefits with applications examples. Technical as well as cost – related benefits will be emphasized.

An overview of the main metrology methods used traditionally for wafer bonding-based applications, as well as new methods adopted based on newest applications fields will be presented.
Revisiting Amorphous LixTiO2: Can x = 1 be Exceeded through Chlorine Modification?
Authors: De Taeye Louis , Vereecken Philippe M.
Published: December 2020

LTO is a commonly used anode material for high power applications, due to its intrinsic high rate performance. LTO requires high temperature processes to crystallize the material, suffers from a low capacity of 600mAh/cm3 and high oxidation potential of 1.5V vs. Li+/Li [1]. TiO2 is a cheap alternative which exhibits high cycle life and requires less stringent high temperature processing. Amorphous TiO2 was shown to reach the theoretical capacity of 1260 mAh/cm3, twice that of LTO. The theoretical limit can only be achieved through nano-scaling of the system or through chlorine modification [2]. Hence, in both cases, all the available Ti+IV atoms are reduced to Ti+III with insertion of Li+ ion upon reductive lithiation step. Despite having twice the capacity of LTO, the energy density of batteries containing a TiO2 anode remains limited by the high oxidation potential (1.8V vs. Li+/Li), and suffer from poor rate performance.

A low temperature ALD process to deposit chlorine modified TiO2:Cl was developed, which allows high levels of chlorine impurities to be incorporated into thin-film electrodes. High level chlorine modification of TiO2 is observed to significantly enhance the Li-ion storage capability of LixTiO2, potentially exceeding x = 1, beyond the current theoretical limit of 1260 mAh/cm3 or 330 mAh/g. In addition, the chlorine modification of TiO2 leads to greatly enhanced rate performance. Finally, when going beyond x>1, the onset potential of oxidation of LixTiO2 shift to lower potentials which is beneficial for the energy density of the cell with TiO2 as anode. Indeed, the onset of oxidation shifts from 1V vs. Li+/Li down to 0.6V vs. Li+/Li, with a capacity exceeding that of LTO obtained below 1.5V vs. Li+/Li.

[1] N. Nitta, F. Wu, J. T. Lee, and G. Yushin, “Li-ion battery materials: Present and future,” Mater. Today, vol. 18, no. 5, pp. 252–264, 2015

[2] S. Moitzheim, J. E. Balder, P. Poodt, S. Unnikrishnan, S. De Gendt, and P. M. Vereecken, “Chlorine Doping of Amorphous TiO2 for Increased Capacity and Faster Li+-Ion Storage”, Chem. Mater., 29, pp. 10007−10018, 2017
Heterostructured Nickel-Rich LiNi0.91Co0.05Mn0.04O2 cathode Materials via Exfoliation-Restacking of Anionic Clay
Authors: Son Youhwan , Yeon Dong-Hee , Park Jun-ho
Published: December 2020

Nickel-rich layered lithium transition-metal oxides, LiNi1−xMxO2 (M = transition metal, x < 2), have been under intense investigation as high-energy cathode materials for rechargeable lithium batteries because of their high specific capacity and relatively low cost. However, the commercialization of nickel-rich oxides has been severely hindered by their intrinsic poor thermal stability at the fully charged state and insufficient cycle life, especially at elevated temperatures. Here, the surface of a nickel-rich layered cathode particles was modified with anionic clay via an exfoliation and restacking route. The nickel-rich layered cathode particles and anionic clay are well-matched with each other regarding electrostatic interactions, allowing the two inorganics to spontaneously self-assemble when mixed with each other in aqueous media. The electron energy loss spectroscopy profile demonstrated a very thin coating layer around 2.5 nm beyond the Ni boundary originating from the cathode particles. The resulting material displayed suppressed gas evolutions as well as thermal and electrochemical properties, which both theoretical and experimental results showed were due to homogenous passivation via a thin coating layer. The cylindrical-type 18650 cell was tested for longer cycles and at an elevated temperature (45 °C) in order to accelerate the side reactions between the active cathode materials and the electrolyte. The prepared cathode material had discharge capacities of 233 mAh/g at 0.2 C and 82.4 % capacity retention after 300 cycles, which showed much improved retention compared to non-surface modified particles (71.0 %). In addition, amount of transition metal dissolution that occurred after cycling, which is strongly related to degradation of cell performances when using Ni-rich cathode materials. Reducing of metal dissolution was successfully achieved by modifying the surface on the cathode material particles and dissolution of Ni ions was dramatically reduced by a factor of 8 compared to non-surface modified particles.

Figure 1
Mesoscale Electrochemical-Mechanical Analyses of Solid-State Non-Planar Conversion Cathodes
Authors: Roberts Scott A. , Ferraro Mark E. , Horner Jeffrey S. , Ng Benjamin , Harrison Katharine
Published: December 2020

In the quest for high performing battery technologies, conversion cathode materials often stand out for producing high energy densities. Combined with non-planar electrode geometries, such as 3D/2.5D battery architectures, conversion cathodes can achieve both high power and energy densities. However, electrochemical conversion processes are often mechanically abusive at the mesoscale, with significant changes in particle volumes leading to high stresses within the electrode. While previous studies have investigated mesoscale stress impacts for a variety of planar cathode materials, the added complication of non-planar electrode geometries complicates our previous understanding, particularly when the geometric features are on the same size as a mesoscale representative volume element.

In this paper, we demonstrate a coupled electrochemical-mechanical model of a 2.5D pillar conversion cathode system. The mesoscale geometry is generated using discrete element models. The electrochemical model consists of species and electrical transport coupled by Butler-Volmer interfacial reaction kinetics. A moving mesh technique is implemented to track the conversion reaction front and separate reacted from unreacted materials. The impact of the electrochemical reaction leads to the generation of mechanical stresses within the electrode structure. We demonstrate how the mechanical response differs between planar and non-planar electrode geometries and explore the role of the geometric feature sizes on stress localization.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
An Investigation of the Electrochemical Processes in Magnesium-Sulfur Batteries By Operando Spectroscopy Techniques
Authors: Bhaghavathi Parambath Vinayan , Zhao-Karger Zhirong , Fichtner Maximilian
Published: December 2020

The high energy density conversion cathode material like sulfur (S) is promising in combination with Mg anode because of the high theoretical capacity (1672 mA h g-1 or 3459 mA h cm-3), as well as their wide abundance and low cost. Magnesium/sulfur (Mg/S) batteries face drawbacks like large over potential between charge/discharge cycles, rapid capacity fading, poor cycling efficiency and low kinetics. Most of these issues are strongly correlated with the electrolytes used in Mg/S cells and the polysulfide shuttling to the Mg anode side. In spite of recent achievements in Mg/S rechargeable batteries, especially in the field of electrolyte and cathode development, a fundamental understanding of the battery chemistry is still missing and needs further exploration.

In the present study, the electrochemical performances of a room-temperature Mg/S battery with a newly designed sulfur composite cathode and a non-nucleophilic magnesium electrolyte (Mg[B(hfip)4]2 in DME solvent) have been investigated [1, 2]. Operando Raman spectroscopy is employed to track the formation of polysulfide species at the cathode of Mg/S cells during the charge/discharge process, while density functional theory (DFT) calculations are used to correlate the Raman modes with a series of polysulfide species (Sx
n-, x = 1–8). Operando Raman spectroscopy proves the chemical transformation from elemental sulfur (S8) via long and short chain polysulfides to magnesium sulfide upon discharge and conversion back to elemental sulfur during charging. Furthermore, the spectral measurements indicate the formation of a nano-crystalline magnesium sulfide with a cubic zinc blende phase at the end of discharge [2].

Impedance studies of the Mg anode and sulfur cathode electrodes of Mg/S cell under static conditions prove that the total cell impedance is mainly dominated by the anode/electrolyte interface due to the formation of a highly resistive passivation layer. Indeed, upon cycling of the Mg/S cell, the amount of polysulfide species migrated to the anode side via dissolution significantly contributes to the increase of the anode overpotential and resistances. Furthermore, under dynamic conditions, the oxidation/reduction potentials applied to the electrodes dramatically influence the anode impedances due to the oxidation/reduction of chemical species present at the Mg anode interphase. The chemical composition, thickness and morphology of the Mg anode/electrolyte interphase layer is investigated by x-ray photoelectron spectroscopy (XPS) with depth profiling and focused ion beam scanning electron microscope (FIB-SEM) techniques.

Reference
s

[1] Z. Zhao-Karger et al, Journal of Materials Chemistry A, 2017, 5, 10815-10820.

[2] Vinayan, B. P. et al., Journal of Materials Chemistry A, 2019, 7, 25490-25502.

Figure 1
Rods-like Sulfur Immobilized on Reduced Graphene Microspheres for Lithium–Sulfur Batteries
Authors: Yeon JeongSeok , Choi Min Sung , Park Ho Seok
Published: December 2020

We demonstrate 2D rod-like nanosulfur (nS)deposited onto microspherical reduced graphene oxide architectures for improved performance of lithium–sulfur (Li–S) batteries. The combined chemistry of a spray-frozen assembly and ozonation drives the formation of a radially oriented open-porous structure and an overall microspherical morphology as well as uniform distribution and high loading of rod-like nS. Moreover, an optimum composition and strong bonding of the rGO/nS hybrid enables the optimization of redox kinetics for high sulfur utilization and high-rate capacities. The resulting rGO/nS hybrid provides a specific capacity and first-cycle Coulombic efficiency of 1269.1 mAh g–1 and 98.5%, respectively, which are much greater than those of ice-templated and physically mixed rGO/nS hybrids and radially oriented open-porous rGO/bulk sulfur with the same hybrid composition. A 4C capacity of 510.3 mAhg–1 and capacity decay of 0.08% per cycle over 500 cycles (70.9% of the initial capacity over 300 cycles) also support the synergistic effect of the rod-like nS strongly interacting with the radially oriented open-porous rGO microspheres.

Figure 1
Multi-Functional TEMPO Derivatives for High-Performance Lithium Oxygen Batteries
Authors: Jeong Jinhyeon , Kim Jonghak , Hwang Chihyun , Song Hyun-Kon
Published: December 2020

Lithium oxygen batteries (LOBs) have been spotlighted as the next generation of rechargeable batteries due to their high theoretical capacity. One of the key issues of LOBs is how effectively lithium peroxide as the discharge product is removed. (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO) was reported as a charge redox mediator to remove lithium peroxide during charge. TEMPO is oxidized to TEMPO+ at 3.70V vs. Li/Li+ and then withdraw electron from lithium peroxide. In this presentation, we present the effects of functional groups attached to 4'-C of TEMPO on LOB performances. Several TEMPO derivatives improved cycling stability significantly. In addition to redox mediation role on charging, a group of TEMPO derivatives promoted disproportionation reaction of superoxide radical during discharging to change the morphology of lithium peroxide. Another group of TEMPO derivatives improved the cycling stability by forming a protective interface film on lithium metal cathode.
Limitation of Redox Mediator in Li-O2 Batteries: Indecomposable By-Products
Authors: Kim Hun , Sun Yang-Kook
Published: December 2020

Redox mediators have been studied passionately to improve energy efficiency and cycle life of lithium-oxygen batteries by facilitating decomposition of the discharge product (lithium peroxide) and, thus, reducing the side reactions at high potential during charging. Nevertheless, the cycling performance of lithium-oxygen batteries with redox mediators is still unsatisfactory; this problem must be verified and resolved for the successful application of redox mediators. In this study, we confirmed that widely used redox mediators cannot decompose by-products on the cathode, leading to passivation of the cathode surface despite the successful decomposition of lithium peroxide. By schematizing the routes for by-products formation, we described the processes by which by-products are accumulated on the cathode in the absence and presence of a redox mediator. Based on the intuitive verification of the unproven relationship between a redox mediator and by-products, we proposed a complementary strategy to overcome the limitations of redox mediator and prevent the accumulation of by-products, which is essential for improvement of lithium-oxygen batteries.

References

W.-J. Kwak, H. Kim, Y. K. Petit, C. Leypold, T. T. Nguyen, N. Mahne, P. Redfern, L. A. Curtiss, H.-G. Jung, S. M. Borisov, S. A. Freunberger and Y.-K. Sun, Nat. Commun., 2019, 10, 1380.

W.-J. Kwak , R. Sharma , D. Sharon , C. Xia , H. Kim , L. R. Johnson , P. G. Bruce , L. F. Nazar , Y.-K. Sun , A. A. Frimer , M. Noked , S. A. Freunberger and D. Aurbach, Chem. Rev., 2020, just accepted. https://doi.org/10.1021/acs.chemrev.9b00609

M. M. Ottakam Thotiyl, S. A. Freunberger, Z. Peng and P. G. Bruce, J. Am. Chem. Soc., 2013, 135, 494.
Study on the Cycling Performance of Li-Metal Anodes Impregnated into 3D Current Collectors for Li-Metal Batteries
Authors: Eom Ji-Yong , Lee Da-Yeon , Kim Seong In , Kang Ji-Hoon
Published: December 2020

Lithium (Li) metal is the most attractive anode material for batteries because of its high specific capacity (3861 mAh/g) and low negative potential (- 3.04 V vs. NHE). However, the Li dendrite growth during Li deposition leads to serious safety problems and poor cycling performance. With durative forming and growing of the Li dendrite during cycling, the accompanying large surface area of SEI layers induces a constant loss of both working Li metal and electrolyte, leading to a low Coulombic efficiency and a rapid capacity decay. Thus, there has been much research effort to achieve the suppression of the Li dendrite formation.

According to the previous reports, employing three-dimensional (3D) current collectors is one approach to reduce the effective current density and delay dendrite growth. In this study, we developed a strategy by impregnating Li metal into the 3D current collectors of nickel (Ni) foam and carbon (C) foam backbone to improve the cycling performance of Li-metal anodes for Li-metal batteries. As a result, Li @ Ni foam and Li @ C foam cells showed better capacity retention for 500 cycles than pure Li metal anodes.
Minerals As Electrode Materials for Ca-Based Rechargeable Batteries: Evaluation of the Pyroxene, Garnet, Melilite and Double Carbonate Groups
Authors: Torres Arturo , Luque Javier , Tortajada José , Arroyo-de Dompablo Elena
Published: December 2020

Rechargeable lithium-ion batteries dominate the consumer electronics and electric vehicle markets. However, concerns on Li availability have prompted the development of alternative high energy density electrochemical energy storage systems. Rechargeable batteries based on a Ca metal anode can exhibit advantages in terms of energy density, safety and cost. The development of rechargeable Ca metal batteries requires the identification of suitable high specific energy cathode materials. This work focuses on Ca-bearing minerals because they represent stable and abundant compounds. Suitable minerals should contain a transition metal able of being reversibly reduced and oxidized, which points to several major classes of silicates and carbonates. A recent work [1] discusses their electrode characteristics based on crystal chemistry analysis and density functional theory (DFT) calculations. The results indicate that upon Ca deintercalation, compounds such as pyroxene, garnet and double carbonate minerals could display high theoretical energy densities (ranging from 780 to 1500 Wh/kg) with moderate structural modifications. As a downside, DFT calculations indicate a hampered Ca mobility in their crystal structures with energy barriers for Ca migration exceeding 2 eV. More recent investigations found a lower energy barrier of 1 eV in the group of melilite with formula Ca2MSi2O7, where Ca ions are in a square antiprism coordination polyhedron and M is a transition metal ion in tetrahedral coordination.

Acknowledgements: Authors are grateful for financial support from European Union H2020-FETOPEN funded project CARBAT-766617.

[1] Torres, Luque, Tortajada, Arroyo-de Dompablo, Scientific Reports 9, 9644 (2019).
Trailblazing Next Generation Sodium Battery Chemistry through Tunable Sodium Phosphorothioates
Authors: Wang Chuanlong , Zhang Yue , Wang Hai , Li Weiyang
Published: December 2020

Next-generation battery chemistry based on earth-abundant elements of sodium and sulfur can deliver a high theoretical specific energy of 1274 Wh kg-1, making low cost battery technologies possible. Nevertheless, the formation of unanchored soluble intermediate sulfur species and the precipitation of low electronically/ionically conductive solids impede the realization of such systems. Herein, by introducing another naturally plentiful element of phosphorus, we invented a new series of sodium phosphorothioates by taking advantage of the chemical affinity among these three elements, which solves the abovementioned challenges. These new materials not only serve as a high capacity cathode but also function as a stabilization reagent for sodium anode, contributing to a novel battery chemistry that delivers high electrochemical potentials and capacity. As a proof of concept, we demonstrate a high-performance sodium battery, showing an initial capacity delivery of 440 mAh g-1 along with a cyclic retention of 80% for over 400 cycles. The superiority of this new battery chemistry is fundamentally investigated by both experimental characterizations and theoretical calculations. This study can lay the groundwork in designing a low cost, high performance sodium battery chemistry that potentially meets the grid-scale energy storage requirements beyond the current lithium ion technologies.

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Doping Phosphorus in Carbon Xerogel via Vaporization for Sodium Ion Batteries
Authors: Deng Changyu , Lu Wei
Published: December 2020

Sodium ion batteries become popular due to their low cost. Among possible anode materials of sodium ion batteries, phosphorus has great potential owing to its high theoretical capacity. Previous researches that yielded high capacity of phosphorus anode used very expensive materials such as black phosphorus and phosphorene. To take advantage of the low cost of sodium ion batteries, we propose a new method to make anode: evaporating red phosphorus and condensing it on carbon xerogel skeleton. The mass ratio of phosphorus, measured by thermogravimetric analysis, is around 11%. Even with large particle size (> 10 μm) and high mass loading (2 mg/cm2), the composite cycled at 200 mA/g yielded 242 mA/g maximum capacity or 1800 mA/g based on phosphorus after subtracting the contribution of carbon. The average degradation rate is 0.06% in first 80 cycles and 0.18% in 300 cycles. The average columbic efficiency is as high as 99.2%. Our research provided new perspectives to make anode and could promote commercialization of sodium ion batteries.

Figure 1