bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Structure and Ion Transport Near Electrode-Electrolyte Interfaces in Lithium-Ion Batteries
Authors: Lordi Vincenzo , Ong Mitchell T. , Verners Osvalds , van Duin Adri C. T. , Draeger Erik W. , Pask John E. 
Published: February 2020

The performance of lithium-ion secondary batteries (LIBs) is strongly tied to ionic transport through electrode-electrolyte interfaces. Solvation structure strongly affects ion mobility, and differences in ion solvation near the interface compared to the bulk may affect conductivity. Furthermore, the formation and evolution of solid-electrolyte interphase (SEI) layers, which impede transport between electrode and electrolyte while passivating the interface, are related to molecular interactions at the interface involving solvent molecules, ions, and the electrode surface. In addition, the chemistry of the electrode surface, in particular the edge termination of graphite electrodes, can impact Li ion transport into the electrode and formation of SEI. Understanding these effects is critical to optimizing battery performance.
Here we present molecular dynamics (MD) simulations of typical organic liquid LIB electrolytes in contact with graphite electrodes to understand the relationship between ion solvation structure and transport near the interface. Results for different graphite terminations are presented and the effect of an electric field is explored. Different prototypical organic liquids, including ethylene carbonate and ethyl methyl carbonate, are compared. We observe that anion mobility in an electric field is much greater than that for Li ions, a phenomenon due to the very different solvation structures. In addition, we observe a barrier to Li insertion into graphite when its surface is hydroxyl terminated. Furthermore, we compare the results of ab initio MD with the empirical reactive forcefield ReaxFF and the non-reactive, non-polarizable COMPASS forcefield and note differences in the predictive power of each technique.
Prepared by LLNL under Contract DE-AC52-07NA27344.
In-Situ Observation of Li-O2 Electrochemical Reactions Using Electrochemical AFM
Authors: Byon Hye Ryung , Wen Rui , Hong Misun 
Published: February 2020

Despite outstanding gravimetric energy density of a nonaqueous lithium-oxygen (Li–O2) battery in regard to promising future energy storage, a true Li–O2 electrochemical reaction has not been deeply understood. In particular, a little knowledge of dynamic Li–O2 process of formation, growth and decomposition of Li2O2 has been known. Here, we present in–situ imaging of the Li–O2 electrochemical reactions using atomic force microscopy (AFM) coupled with electrochemical tester.[1,2]

A highly oriented pyrolytic graphite (HOPG) and metallic lithium were employed to working and counter/reference electrodes, respectively, which were fully immersed in O2 gas-saturated tetraethylene glycol dimethyl ether (tetraglyme) containing 0.5 M of LiTFSI (LiN(SO2CF3)2). Cyclic voltammetry was carried out at a potential range of 2.0-4.5 V with a scanning of HOPG surface by an insulating AFM tip in an Ar-filled glove box, which offered almost identical condition to the actual Li-O2 cell. In addition, the AFM tip scanning for imaging did not significantly disturb the growth/decomposition process of Li2O2.
Upon the oxygen reduction reaction (ORR), the nucleation of nanoparticle (diameter = 3–10 nm) was observed at the step edge of HOPG. These nanoparticles grew up to a diameter of 200 nm and migrated to the terrace of HOPG. When the potential approached to 2.0 V, new morphology products having rectangular and elongated nanoplates were rapidly formed at the edge of HOPG, which became predominant products for further reduction, thus constructing a thick Li2O2 film, demonstrated by X-ray photoelectron spectroscopy (XPS). Interestingly, the size of Li2O2 nanoplates on the top surface of Li2O2 film was much smaller than the one on the HOPG, which was probably attributed to slow charge transport according to growth of thick Li2O2 film having the poor electronic conductivity. The Li2O2 was decomposed upon oxygen evolution reaction (OER), where the thick and dense Li2O2 film delayed its decomposition and demanded for higher oxidation potential compared to the thin and low density of Li2O2. For control experiments, we replaced the ether-based electrolyte and HOPG electrode with carbonate and nanoporous gold, and also extended the voltammetry cycling number. These conditions provided different morphology of products and chemical identifications, which would be discussed in the presentation.

References

[1] Wen, R.; Hong, M.; Byon, H. R. J. Am. Chem. Soc.
2013, 135, 10870-10876.
[2] Wen, R.; Byon, H. R. Chem. Commun.
2014, 50, 2628-2631.
Invited: Solidstate Engineering at Northwestern University
Authors: Razeghi Manijeh , McClintock Ryan 
Published: February 2020

III-V semiconductors are playing an increasingly important role in the semiconductor industry as silicon technology slowly researches maturity. A diverse, and expanding, array of III-V semiconductor materials is currently being studied for next generation applications including optoelectronics and power devices. Under the guidance of Professor Manijeh Razeghi, Northwestern University has put itself on the map with a dedicated solidstate engineering faculty and state of the art facilities—all targeted towards training the next generation of solidstate engineers to work with these fundamental semiconductor materials. This is in marked contrast to many universities which focus primarily on the application of power devices, but not the design and construction of these devices.
Northwestern University has a dedicated cleanroom facility with multiple MOCVD and MBE system, and a state of the art toxic gas handling system dedicated to the growth of III-V semiconductor materials. Northwestern also has multiple facilities dedicated to the processing of these semiconductor materials into packaged devices, as well as the expertize and knowledge to test and characterize a wide array of III-V semiconductor devices. These facilities are currently used by undergraduate and graduate students, as well as post-doctoral scholars and research faculty, and support an integrated solid-state engineering curriculum.
The solid state engineering curriculum consists of a core focused on developing a fundamental understanding of theory, design and physics; semiconductor material growth and characterization; and device processing and testing. Three Textbooks have been developed to support this core curriculum:
Fundamentals of Solid State Engineering, 3rd ed.
;
Technology of Quantum Devices
; and
the MOCVD Challenge, 2nd Ed.
This curriculum then branches off into two major thrusts: “electronic transport” and “optoelectronics”. The electronic transport thrust contains classes covering low and high-power electronic devices.
This talk will review the current solidstate educational curriculum at Northwestern and our future plans to expand the coverage of wide-bandgap power devices in order to better educate the next generation of scientists and engineers to work in this important and growing area.
On the Power-Handling Capability of Wide Bandgap (WBG) Semiconductor Power Switching Devices
Authors: Shenai Krishna 
Published: February 2020

Power switching devices made using wide bandgap (WBG) semiconductors such as Silicon Carbide (SiC) and Gallium Nitride (GaN) have the potential to make transformative impact on electrical energy generation, transmission, distribution and conditioning [1]. Although SiC power diodes and power MOSFETs are commercially available for voltage ratings up to 1,700 volts, a careful review of the published data suggests that reliability of WBG power devices may be severely compromised compared to identically rated silicon power devices. For example, dv/dt, avalanche, and safe-operating area (SOA) of SiC power diodes and MOSFETs are inferior to silicon power devices with identical ratings. This paper will present a simple physics-based analysis of the power handling capability of WBG power devices and explain the possible causes of lower reliability ratings.
[1] K. Shenai et al, “Current status and emerging trends in wide bandgap (WBG) semiconductor power devices,” ECS J. Solid State Sci. and Tech.
2(8), N3055-N3063, Jul 2013
Crystalline Submicrometer Spherical Particles with High Refractive Index for Optical Applications
Authors: Koshizaki Naoto , Ishikawa Yoshie 
Published: February 2020

Nanoparticles are generally aggregated in liquid to reduce surface energy, and therefore surface modification of the nanoparticles is important to obtain well dispersed nanoparticles in liquid. Thus the aggregation of nanoparticles should be avoided for practical use of nanoparticles as much as possible.
Recently we found that B4C submicrometer spherical particles by irradiating low-fluence laser onto the B nanoparticles dispersed in organic solvent through the high-temperature carbonization reaction. Furthermore, we also found that similar submicrometer spherical particles were produced for various kinds of materials, such as metals (Au, Ag, etc.), oxides (ZnO, TiO2, etc.) and semiconductors (Si, GaP, etc.) using nanoparticles as raw materials and by unfocused laser beam irradiation.
In these cases, raw nanoparticles are presumably not vaporized nor ablated but melted by nanosecond laser irradiation to form liquid droplets, resulting in spherical particle formation by quenching. Thus, this process “laser melting in liquid” is evidently different from the conventional technique, “laser ablation in liquid” for nanoparticle fabrication using high-fluence laser irradiation in liquid.
More importantly, the particle size increased from nano-size to sub-micrometer size by laser melting in liquid. This is because aggregated nanoparticles melt together by optical absorption and subsequent temperature increase over melting temperature to form larger spherical particles. Thus the aggregation of nanoparticles plays an important role in submicrometer spherical particle formation.
Here we present our recent results on the laser melting in liquid, such as the effect of processing parameters on the products. Especially we discuss the effect of raw particle size by dynamic light scattering and zeta potential on the product morphology and generated particle size. Physicochemical calculation of temperature estimation based on the particle heating-melting-quenching model by laser irradiation is compared with the experimental results. Optical and medical applications of submicrometer spheres is also demonstrated.
Chemically Integrated Hybrid 2-D Materials for Flexible Energy Storage Devices
Authors: Yu Guihua 
Published: February 2020

Two-dimensional (2-D) materials have been a promising material platform for making powerful energy devices including highly flexible energy storage devices. Owing to their advantageous features of flexibility, large surface area and open ion transport pathway within 2D layers, highly electroactive 2-D transition-metal oxide and phosphate nanosheets materials show promise in flexible supercapacitors with high power and energy densities. Here I will present our recent progress on chemically integrated hybrid 2-D materials to build ultraflexible, high-performance energy storage devices. One example is the building of integrated hybrid vanadyl phosphate VOPO4/graphene ultrathin-film solid-state pseudocapacitors (1). The other is the development of MnO2/graphene hybrid nanostructures based flexible planar supercapacitors (2).
Rational material and structural design demonstrated in these studies show hybrid structures not only take advantage of excellent electronic conductivity of graphene nanosheets but also introduce more electrochemically active surfaces for absorption/desorption of electrolyte ions, which can greatly facilitate charge transport during electrochemical processes.
References
(1) Wu, C.; Lu, X.; Peng, L.; Xu, K.; Peng, X.; Huang, J.; Yu, G.; Xie, Y. Nature Communications 2013, 4, 2431.
(2) Peng, L.; Peng, X.; Liu, B.; Wu, C.; Xie, Y.; Yu, G. Nano Letters 2013, 13, 2151.
Effects of Morphology on Nanostructured Cobalt Oxides for Oxygen Evolution Reaction
Authors: Cho Sung-Hwa , Roh Gilltae , Park Jun-Young 
Published: February 2020

The oxygen evolution reaction (OER) is important process in water-splitting electrochemical devices for oxidation of water to molecular oxygen [1-4]. In particular, OER is the most important reaction process because the overall cell efficiency depends strongly on the reaction rate of the OER. Until now, noble metal catalysts such as iridium, ruthenium, and platinum have shown excellent performances for the OER and even ORR in fuel cell conditions [5]. However, these noble metal catalysts have disadvantage for making commercialization of such electrochemical devices in terms of high cost and limited durability [6, 7].
In order to cope with these issues, in this work, various transition metal oxides such as manganese oxides and cobalt oxides are investigated for replacing expensive noble metals of water-splitting electrochemical cells with enhanced durability [8, 9]. To achieve high efficient electrocatalyst for OER, in addition, various nanostructured metal oxide catalysts are synthesized by the hydrothermal method using nitrate or acetate-based precursors [10].
Synthesized catalysts are physicochemically characterized by X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM). For analysis of electrochemical properties, cyclic voltammetry (CV) and OER are measured by rotating disk electrode (RDE) system. A Pt wire and Ag/AgCl electrode are used as a counter electrode and a reference electrode in 0.1 M KOH electrolyte. OER activity is measured by the linear sweep voltammetry (LSV) from 1.2 to 1.7 V at a scan rate of 5 mV s-1
to compare each nanostructured transition metal oxide powders.

Y. Liang, Y. Li, H. Wang, J. Zhou, J. Wang, T. Regier, H. Dai, Nature Materials, 10, 780 (2011).

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L. Qu, Y. Liu, J.B. Baek, L. Dai, ACS Nano, 4, 1321 (2010).

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Y. Dong, K. He, L. Yin, A. Zhang, Nanotechnology, 18, 435602 (2007).

T. Reier, M. Oezaslan, P. Strasser, ACS Catal., 2, 1765 (2012).

A. J. Esswein, M. J. McMurdo, P. N. Ross, A. T. Bell, T. D. Tilley, J. Phys. Chem. C, 113, 15068 (2009).

X. Rui, H. Tan, D. Sim, W. Liu, C. Xu, H. H. Hng, R. Yazami, T. M. Lim, Q. Yan, J. Power Sources, 222, 97 (2013).

J. Suntivich, K. J. May, H. A. Gasteiger, J. B. Goodenough, Y. Shao-Horn, Science, 334, 1383 (2011).

* Corresponding authors: jyoung@sejong.ac.kr (J.-Y. Park).
Enhanced Oxygen Evolution Activity of 3D Nanostructured Cobalt Oxides through Doping with Various Transition Metal Oxides
Authors: Kim Nam-In , So InSeop , Park Jun-Young 
Published: February 2020

Photoelectrochemical water-splitting is one of the most renewable and clean ways to produce hydrogen by water electrolysis [1]. However, the oxygen evolution reaction (OER) in anode side of photoelectrochemical water-splitting system shows sluggish kinetics with the high polarization loss due to the 4-electron pathway likewise oxygen reduction reaction (ORR) in fuel cell operating conditions [2-5].
Up to now, noble metals, such as iridium, ruthenium and platinum, have still used as OER catalysts [6]. In comparison with these noble metal catalysts, studies of transition metal oxide catalysts (TMOCs) for photoelectrochemical water-splitting systems have not carried out intensively, although they have similar (or more active) properties about OER [7, 8]. In addition, various state-of-art nanotechnologies for fabricating TMOCs may contribute to improve OER properties significantly for water-splitting [9, 10].
In this work, a variety of nanostructured cobalt oxides (NCOs) are synthesized by the hydrothermal method using urea, hydrogen peroxide and polyvinylpyrrolidone. Then, various transition metal oxides are doped to NCO matrix during hydrothermal reaction. Their physicochemical properties were confirmed by using various analytic techniques such as SEM, TEM, BET, and XRD.
For electrochemical characterizations, a rotating disk electrode system is adopted with an Ag/AgCl reference electrode and a Pt counter electrode in 0.1 M KOH electrolyte. A pretreatment where cyclic voltammetry (CV) post-purging nitrogen gas in the potential range of 0.05 – 1.2 V versus reversible hydrogen electrode (RHE) conducted at a scan rate of 100 mV s-1 for 50 cycles is used for activation of catalyst surface. The OER activity is measured by linear sweep voltammetry (LSV) from 1.2 to 1.7 V at a scan rate of 5 mV s-1 and is compared the oxygen evolution activity at specific current density.

J. Jhang, K. Sasaki, E. Sutter, R. R. Adzic, Science, 315, 220 (2007).

Y. Liang, Y. Li, H. Wang, J. Zhou, J. Wang, T. Regier, H. Dai, Nature Materials, 10, 780 (2011).

J. Suntivich, K. J. May, H. A. Gasteiger, J. B. Goodenough, Y. Shao-Horn, Science, 334, 1383 (2011).

J. Suntivich, H. A. Gasteiger, N. Yabuuchi, Y. Shao-Horn, Nature Chemistry , 3, 546 (2011).

I. C. Man, H. Y. Su, F. C. Vallejo, H. A. Hansen, J. I. Martínez, N. G. Inoglu, J. Kitchin, T. F. Jaramillo, J. K. Nørskov, J. Rossmeisl, ChemCatChem, 3, 1159 (2011)

T. Reier, M. Oezaslan, P.Strasser, ACS Catal., 2, 1765 (2012).

Y. J. Sa, K. Kwon, J. Y. Cheon, F. Kleitz, S. H. Joo, J. Mater. Chem. A, 1, 9992 (2013).

J. Y. Cheon, C. Ahn, D. J. You, C. Pak, S. H. Hur, J. Kim, S. H. Joo, J. Mater. Chem. A, 1, 1270 (2013).

C. A. Wang, S. Li, L. An, Chem. Comm., 49, 7427 (2013).

X. Rui, H. Tan, D. Sim, W. Liu, C. Xu, H. H. Hng, R. Yazami, T. M. Lim, Q. Yan, J. Power Sources, 222, 97 (2013).

* Corresponding authors: jyoung@sejong.ac.kr (J.-Y. Park)
Mass Transfer in an Anode-Supported Honeycomb Solid Oxide Fuel Cell
Authors: Kotake Shota , Nakajima Hironori , Kitahara Tatsumi 
Published: February 2020

An anode-supported honeycomb SOFC can achieve high volumetric power density and improve thermo-mechanical durability at high temperatures. We have so far fabricated the honeycomb cell with a cathode layer of LSM and an electrolyte layer of 8YSZ on a porous anode honeycomb substrate of Ni/8YSZ. The anode-supported honeycomb cell exhibited promising volumetric power densities. Effect of flow channel configurations on the cell performance was investigated in terms of the hydrogen partial pressure distribution in the cell under operation as well[1].
In the present study, current-voltage and current-power density characteristics of the cells having different porous substrate thicknesses and anode/cathode flow channel configurations are studied under different flow rates and partial pressures of fed hydrogen. We also investigate performance changes by forced hydrogen flow through the porous anode substrate taking advantage of valves connected to each outlet of the honeycomb cell.
Reference

S. Kotake, H. Nakajima, and T. Kitahara, “Flow Channel Configurations of an Anode-Supported Honeycomb Solid Oxide Fuel Cell” ECS Trans.,
57(1), B815 (2013).
Cation Intercalation and High Volumetric Capacitance of Two-Dimensional Titanium Carbide
Authors: Lukatskaya Maria R. , Ren Chang E. , Mashtalir Olha , Dall'Agnese Yohan , Barsoum Michel W. , Gogotsi Yury , Simon Patrice 
Published: February 2020

We recently produced a new 2-D material, viz. Ti3C2, by selectively etching aluminium from a MAX phase Ti3AlC2 and labelled it MXene. MXenes represents a large family of transition metal carbides and carbonitrides, not just a single phase. MXenes allow a variety of chemical compositions and are establishing themselves as a new class of two-dimensional materials. MXenes possess good in-plane conductivity, which in combination with their rich surface chemistry makes them attractive for electrical energy storage applications. However their use in electrochemical capacitors was only recently demonstrated (Lukatskaya et.al, Science, 2013).
Here, we report on the intercalation of Li+, Na+, Mg2+, K+, NH4
+, and Al3+ ions between the 2D Ti3C2Tx layers. In most cases, the cations intercalated spontaneously. The intercalation of some ions, notably Al3+, can be promoted electrochemically. We also report on intercalation-induced high capacitance of >300 Farads per cubic centimeter (much higher than that of porous carbons) of flexible Ti3C2Tx paper electrodes in aqueous electrolytes. Material showed no degradation of the capacitive properties after more than 10,000 cycles. Several different electrochemical techniques were employed to understand the mechanism of charge storage, such as cyclic voltammetry, electrochemical impedance spectroscopy and EQCM.
Lukatskaya, M.R., et al., Cation Intercalation and High Volumetric Capacitance of Two-Dimensional Titanium Carbide. Science, 2013. 341(6153): p. 1502-1505.
The Effect of Etching Temperature upon the Optical Reflactance on Silicon Nanowires Grown By Electroless Etching
Authors: Velez Victor H. , Mertens Robert George , Sundaram Kalpathy B 
Published: February 2020

THE EFFECT OF ETCHING TEMPERATURE UPON THE OPTICAL REFLACTANCE ON SILICON NANOWIRES GROWN BY ELECTROLESS ETCHING

The antireflective nature of Silicon nanowires (SiNW’s) revealed by their black color and dull appearances have drawn the attention of researchers [1]. It may eliminate the need for antireflective coating on these nanostructures to reduce energy losses in solar cells [2]. SiNWs arrays prepared by electroless etching method can significantly suppress light reflection across the visible spectrum. Optical reflectance analysis on SiNWs fabricated at different temperatures (Fig. 1) show a significantly decrease in optical reflectivity down to 1.5% at 25°C.
Enhanced optical reflectance may be achieved at lower etching solution temperatures. Low temperatures slow the kinetics reaction that would grew uniform and well aligned SINWs (Fig. 2a) contrary to randomly direction nanowires grow at high temperatures (Fig. 2b). A uniform growing of SiNWs could optimize nanowire spacing that would improve charge collection and enhance optical reflectance [3].
In this experiment a Cary 100 UV-Visible Spectrometer was used for reflectance analysis and silicon (Si) wafers were dipped for 15 minutes at different temperatures (25°C, 35°C, 45°C, 55°C and 70°C) in an electroless solution prepared in a petri dish containing silver nitrate (AgNO3) and hydrofluoric acid (HF) [4].