bluuebunny/crossref_metadata_2025 huggingface dataset:
Nmr's Perspective of Speciation Process in Lithium Sulfur Batteries
Authors: Wang Hao , Sa Niya , He Meinan , Vaughey John T. , Nazar Linda F , Balasubramanian Mahalingam , Key Baris , Gallagher Kevin G.
Published: February 2020

The understanding of the reaction mechanism and temporal speciation of the lithium sulfur batteries is challenged by complex polysulfide disproportionation chemistry coupled with the precipitation and dissolution of species. In this report, for the first time, we present a comprehensive method to investigate lithium sulfur electrochemistry using in situ
7Li NMR spectroscopy, which is capable of quantitatively capturing the evolution of the soluble and precipitated lithium-(poly)sulfides during electrochemical cycling. The method presented here to study the lithium sulfur battery system using in situ NMR spectroscopy can be readily applied in electrolyte/additives development and lithium protection research, and a foment clear understanding about the speciation process will accelerate electrolyte development. New information collected about the battery mechanism will not only advance Li-S sulfur battery research but also shed light to the lithium metal protection schemes.
The Effects of Electrolyte Additives on Li4Ti5O12 and How They Impact Gassing
Authors: Milien Mickdy S , Hoffmann Jennifer , Li Jing , Payne Martin , Stephenson Scott , Sans John , Lucht Brett L
Published: February 2020

Batteries consisting of Li4Ti5O12 (LTO) anodes do not require the formation of a solid electrolyte interface to deliver robust high-rate performance at room temperature, however performance suffers at elevated temperatures due to gassing. Research has linked this gassing to the instability of the electrolyte on the surface of charged LTO at elevated temperatures. If this is the case a passivation layer that prevents the electrolyte from coming into contact with the charged surface of LTO should hinder gassing. Several classes of electrolyte additives have been investigated in Li4Ti5O12/LiMn2O4 coin cells and pouch cells. ATR-FTIR and X-ray photoelectron spectroscopy has been used to gain an understanding of the surface films formed with different additives while in-situ gas measurements based on Archimedes’ principle and gas chromatography have given insight into how the implementation of these additives affects gassing. The results from this study enable the selective design of surface films for LTO anodes, which impedes gassing at elevated temperatures without sacrificing performance.
Engineered Current Collector Interface for High Energy Density Li-Ion Batteries
Authors: Ventrapragada Lakshman K , Podila Ramakrishna , Rao Apparao M
Published: February 2020

Li-ion rechargeable batteries (LIBs) are the most promising candidates for use in electric and hybrid electric vehicles (EVs and HEVs) due to their high operating voltage and superior energy density compared to other conventional batteries such as the Ni-metal hydride battery. To enable cost-effective and long-lasting EVs, DoE estimates that the performance of present battery systems must be improved by at least four times without increasing the cost. LiFePO4 (LFP) emerged as a competitive cathode material for next-generation LIBs due to its remarkable stability and non-toxicity but they suffer from low electrical conductivity. While the addition of carbon improves the in-plane electrical conductivity, it fails to provide a conducting interface between the LFP/C/binder film and the current collector. This interfacial resistance at the current collector and active material interface (CCAMI) is critical for achieving high power density and rate capability but is often neglected. We addressed this issue by engineering the CCAMI with carbon nanotubes (CNTs). Previously, we demonstrated two roll-to-roll binder-free processes for coating Al foils with CNTS: (i) a CVD-based process for directly growing vertically aligned CNTs (VACNTs) on bare kitchen-grade Al foils [1], and (ii) a spray-coating process for coating industrial-grade Al foils with randomly oriented CNTs [2]. The above mentioned processes eliminate the need for a binder and thereby reduce both the dead weight of the inactive material and the CCAMI resistance. Specifically, we found that the VACNTs- or randomly oriented CNTs-coated Al foils obtained via our roll-to-roll processes enhance the areal (/gravimetric) capacity of LFP by >65% (/>50%) at low C-rates (<2 C), and by >85% (>70%) at high C-rates (>2 C). Moreover, the improved CCAMI resulted in gravimetric energy densities up to 360 Wh/kg and power densities up to 200 W/kg with much higher power capability (increased charge capacity at high discharge rates). Thus, this study describes an attractive approach for improved CCAMI, which is scalable and compatible with existing industrial protocols for coating LFP and takes us many steps closer to the commercial deployment of LIBs in HEVs and EVs.

[1] M. R. Arcila-Velez et al., Nano Energy. 8 (2014) 9–16. doi:10.1016/j.nanoen.2014.05.004.

[2] M. Karakaya et al., Appl. Phys. Lett. 105 (2014). doi:10.1063/1.4905153.
Composite Tin Dioxide-Titanium Dioxide Nanostructured Thin Film Electrodes As Lithium-Ion Anodes
Authors: Kacica Clayton Thomas , Wang Louis S. , Chadha Tandeep Singh , Biswas Pratim
Published: February 2020

An aerosol-chemical vapor deposition technique (ACVD) was utilized in order to deposit highly oriented, one-dimensional nanostructured metal-oxide thin films. Film morphology was controlled using various system parameters in order to obtained the desired columnar morphology. Tin dioxide (SnO2) was chosen as an electrode material due to its high theoretical charge capacity (790 mA-h-g-1), and titanium dioxide (TiO2) was chosen for its remarkable stability and low volume change during charging. The columnar morphology is particularly well suited to SnO2 as the space between the columns allows for accommodation of the large volume expansion the material experiences during charging. Electrodes of SnO2 columnar nanostructures were first synthesized using ACVD by depositing the structures directly on to the current collector. Depositing directly onto the current collector eliminates the need for binding agents and conductive additives during battery fabrication. Then a layer of TiO2 was deposited on the surface of the SnO2 columns using atomic layer deposition. A variety of column heights, ranging from 500 nm to 2 um, and TiO2 layer thickness, ranging from no TiO2 to a 100 nm layer, were synthesized and their electrochemical properties investigated. For all electrochemical characterization experiments, Swagelok-type coin cells were fabricated using lithium foil as a counter electrode and 1M LiPF6 in 50/50 (v/v) EC/DEC as an electrolyte. Optimal electrochemical performance was observed in electrodes with a height of 800 nm and a 15 nm layer of TiO2. A rate capability test was performed to determine how the capacity of the electrodes changed at charging rates ranging from 100-2000 mA-g-1. A stable capacity of 410 mA-h-g-1 was obtained at a charge rate 1000 mA-g-1; rapid capacity fade was observed at higher rates. Galvanostatic charge-discharge was performed for each cell for 100 cycles or until failure at a charge rate of 400 mA-g-1, corresponding approximately to a charge rate of C/2. For the optimal electrode an initial irreversible capacity of 1164 mA-h-g-1 was observed as well as a stable capacity of 530 mA-h-g-1 after 100 cycles. This demonstrates a low cost synthesis of high performance anodes which provides an alternative to conventional electrode synthesis.
Ordered and Disordered Hybrid Tunnel Structured Manganese Oxides for Na-Ion Batteries
Authors: Byles Bryan , Pomerantseva Ekaterina
Published: February 2020

Through modification of previously developed hydrothermal techniques, we synthesize two tunnel structured manganese oxides with novel hybrid tunnel configurations and investigate their behavior in Na-ion batteries. Tunnel manganese oxides represent a promising class of materials for Na-ion batteries due to their low cost, low toxicity, and high electrochemical activity. The two materials studied in this work contain unique combinations of structural tunnels composed of varying amounts of MnO6 octahedra surrounding stabilizing Na+ ions, resulting in numerous different tunnel dimensions within individual nanostructures. Through cross-sectional TEM analysis, the ordered phase was found to consist of a systematic combination of 2x2, 2x3, and 2x4 octahedra tunnels. The disordered phase, on the other hand, was found to consist of a more random and nonuniform distribution of not only 2xn (n=2, 3, 4, 5, 6) tunnels, but also larger 3x3 octahedra tunnels. Moreover, although both materials were synthesized with a nanowire morphology, the disordered phase is found to be composed of nanowires with smaller diameter.

We investigate these two materials as cathodes for Na-ion batteries and find that upon first discharge, the ordered phase exhibits a capacity nearly 300 mAh g-1, while the disordered phase exhibits a capacity of just below 200 mAh g-1. Upon further cycling, however, the disordered phase maintains a greater amount of its initial capacity, indicating that although the better defined tunnel structure may be advantageous for greater initial ion intercalation capacity, the disordered phase shows a greater degree of electrochemical stability. The rate performance of these two materials is discussed in relationship to the different diffusion pathways present in the materials, as well as the structural stability of the two phases upon repeated ions insertion and deinsertion. The performance of these materials is also compared to tunnel manganese oxides with pure tunnel configurations, and the advantage of having such a hybrid tunnel configuration is also emphasized. This work highlights the performance of two similar novel cathode materials for Na-ion batteries, as well as the relationship between the degree of structural order in manganese oxides and their electrochemical behavior in Na-ion batteries.
Hybrid Cathode of LiFePO4 and Activated Carbon Prepared with a Porous Al Current Collector and Its Battery Performance
Authors: Tsuda Takashi , Gunji Takao , Tanabe Toyokazu , Kaneko Shingo , Ohsaka Takeo , Soma Naohiko , Itagaki Kaoru , Matsumoto Futoshi
Published: February 2020

In order to improve both energy and power densities while durability of the battery is maintained, a layer of LiFePO4 layer which has characteristic of high energy density is formed on one side of the Al current collector and a layer of activated carbon which has characteristic of high power density were formed on the other side of the Al current. The full cell is constructed with hybrid cathode and graphite anode (Fig. 1). When high current densities are used in the discharging process of the full cell, the discharging reaction occurs mainly at the part of activated carbon in the hybrid cathode. After discharging, Li ions which are doped in the activated carbon move to the LiFePO4 layer (energy transfer from activated carbon to LiFePO4 electrode) until the electrode potentials of the activated carbon and LiFePO4 layers are equal. Therefore, the hybrid cathode can combine both high power and energy densities.

Fig. 1 schematic drawing of a full cell of hybrid cathode/graphite anode.

Figure 1
Nanoimprinting of Woodpile Electrodes for 3D Lithium-Ion Microbatteries with Both High Capacity and Power
Authors: Li Wenhao , Zhou Yiliang , Howell Irene , Gai Yue , Carter Kenneth R. , Watkins James J.
Published: February 2020

The trend of device downscaling drives the corresponding need for power source miniaturization. With footprint area being the determinant form factor for on-chip battery systems, enhancement of areal energy and power density is urgently needed. Due to the 2D configuration limit, it is impractical for a conventional thin film battery to possess high capacity and power simultaneously.

Here, we show that a novel 3D woodpile electrode, made from TiO2 nanoparticles using solvent-assisted nanoimprint lithography (NIL), can remarkably enhance both the capacity and power of a lithium-ion battery (LIB). With the convenience of sequential imprinting, woodpile electrodes of different heights are readily made in a “stack-up” manner, resulting in a proportional increase of capacity, which is hard to achieve in thin film batteries. Little evidence of specific capacity decrease was observed as the structure height increased by stacking additional layers. These 3D electrodes boast superior rate performance with 1.5- to 6-fold improvement of the specific capacity (compared to 2D counterpart) during fast cycling (up to 15 C) due to the structure’s large surface area. The TiO2 woodpile proved to be a strong candidate for the anode of a high-performance LIB. More importantly, this work demonstrates the great potential of NIL as a platform to create high density architectures for energy storage devices. The strategy described here can be potentially expanded to other electrochemical systems.
Sulfonation of Graphene Oxide for Fuel Cells Electrode and Membrane Applications
Authors: Morales-Acosta Diana , Benavides Roberto , Cuara-Diaz Edgar , Rodríguez-González Jose Alberto , Fernández Tavizón Salvador
Published: February 2020

Graphene oxide (GO) and reduced graphene oxide (rGO) have been widely used for high capacity energy conversion and storage in fuel cells and lithium ion batteries, respectively. Particularly, for proton exchange membrane fuel cells (PEMFC) applications the incorporation of sulfonic acid functional groups (-SO3H) into GO/rGO structure has emerged as a powerful strategy to produce promising new support of noble catalysts and ionomer materials, due to a significant increase in the hydrophilicity of rGO improving the nano-catalyst dispersion and ion-exchange capacity (IEC). In this study, GO was synthesized and sulfonated (sGO) for the development of electrodes and membranes. GO was obtained by a modified Hummer’s method from graphite powder, thermally reduced and sulfonated by means of two sulfonating agents: sulfuric acid and aryl diazonium salt of sulfanilic acid. The influence of the sulfonation agents on the physicochemical properties of rGO-SO3H was evaluated through XRD, TGA, FT-IR and Raman techniques. Electrochemical behavior of both materials as modified glassy carbon electrode was investigated in K3FeCN6 solution as a reference redox system. The results demonstrated that the sulfonated materials have superior electron transfer activity and electrochemical properties compared to GO. In addition, the IEC for a commercial membrane modified with rGO-SO3H improved significantly.
Electrochemical Behavior By DFT of Nanostructured Carbon Surfaces Modified By S or N
Authors: Montiel-Macias Elizabeth , Balbuena Perla B , Verde Gómez Ysmael
Published: February 2020

The oxygen reduction reaction (ORR) is the principal reaction at the cathode side in low-temperature fuel cells (e.g., polymer electrolyte fuel cells (PEFCs), direct methanol fuel cells (DMFCs)) and in metal-air batteries. Due to the slow ORR kinetics and stability issues of the catalyst in the electrochemical environment of fuel cells, precious metals are used for promoting the ORR at the cathode side. However, due to the scarcity and high cost of precious metals, alternatives to replace or reduce the amount of the metal are necessary. As a promising alternative, new carbon nanomaterials doped with heteroatoms as N and S have been investigated. To characterize this alternative, first-principles computational methods are useful tools to explain the influence of heteroatom doped carbon materials on the adsorption/reaction phenomena associated with the ORR. In this context, we present the electrochemical behavior of the surface reactions on nanostructured carbon materials doped with sulfur or nitrogen, by computational modeling using density functional theory (DFT). We discuss the adsorption/reaction phenomena occurring during synthesis and catalysis processes on carbon structures modified with dopant S or N atoms. The analysis is related to the experimental synthesis and electrochemical performance of the new materials.
(Invited) Tube^2
Authors: Ng Allen , Wang YuHuang
Published: February 2020

Atomically-thin materials such as single-walled carbon nanotubes and graphene are prone to chemical attack because all of the constituent atoms are exposed. Here we describe the synthetic creation of a tube-in-a-tube (Tube^2) semiconductor and their implications on biochemical sensing. A Tube^2 is equivalent to a pristine single-walled carbon nanotube (SWCNT) nested within a chemically tailored, impermeable, and atomically-thick functional shell. Compared with SWCNTs and graphene, electrical sensors created using Tube^2 can be readily tailored with robust covalent chemistries to enable chemical selectivity while maintaining exceptional SWCNT-like sensitivity. Recent progress from our lab as well as some of the critical challenges and opportunities in this area will be discussed.
Effects of Chemically-Introduced Structures on Near Infrared Photoluminescence of Locally Functionalized Single-Walled Carbon Nanotubes
Authors: Shiraki Tomohiro , Shiraishi Tomonari , Onitsuka Hisashi , Juhász Gergely , Nakashima Naotoshi
Published: February 2020

Semiconducting single-walled carbon nanotubes (SWNTs) show near infrared photoluminescence (NIR PL) based on the Van Hove singularity in the one-dimensional structures. Recently, PL enhancement with wavelength shifts of the SWNTs has been reported through a very limited amount of chemical modification by oxygen atom doping and sp3 defect doping on the sp2networks.[1-3] In this study, we have examined modulation of the PL properties from a view point of structural design of the modified sites on the local-f-SWNTs using designed molecules.[4,5]

Bisdiazonium compounds (2Dz) are newly synthesized and we find that the local-f-SWNTs using 2Dz (SWNT/2Dz) shows new red-shifted PL.[4] Namely, the emission peak appears at 1256 nm which is remarkably red-shifted than those of pristine SWNTs (985 nm) and mono-functionalized SWNTs (SWNT/1Dz, 1129 nm), as shown in Figure. It is considered that the chemical modification using 2Dz provides an emissive site with a narrower band gap on the SWNTs owing to local dissociation of a degenerate energy band through modification-induced symmetry breaking of the SWNT. Moreover, wavelengths of the new PL are changed with dependence of the methylene linker length of 2Dz.

Other structural factors for PL modulation of local-f-SWNTs will be presented at the meeting.

References: [1] Weisman, R. B. et al., Science
2010, 330, 1656-1659. [2] Wang, Y. et al., Nat. Chem.
2013, 5, 840-845. [3] Nakashima, N. et al., J. Phys. Chem. C
2016, 120, 15632-15639. [4] Nakashima, N. et al., Sci. Rep.
2016, 6, 28393. [5] Nakashima, N. et al., Chem. Commun.
2016, 52, 12972-12975.

Figure 1
(Invited) Toward the Electrochemical Growth of Single-Walled Carbon Nanotubes from Ambient Carbon Dioxide
Authors: Douglas Anna , Carter Rachel E. , Pint Cary L.
Published: February 2020

To address the rising levels of CO2 in the atmosphere, the conversion of CO2 into secondary chemicals and materials offers the most economically viable approach to solve this global challenge. However, state-of-the-art efforts to convert CO2 into low-value commodities and fuels, such as methanol, suffer from low efficiencies, low value of the commodity, and expensive catalysts and processes. Here we discuss an alternative approach where CO2 is captured in a molten carbonate medium from air, and split into its elemental constituents in the presence of a catalytic electrode surface to form carbon nanotubes (CNTs). This general approach was developed in the 1960's for the deposition of carbon, [1-2] and recently shown to be adapted without composition control of bulk catalytic electrodes to the growth of large-diameter (> 100 nm) CNTs [3]. Here, we demonstrate the ability to rationally engineer the anode and cathode electrodes to controllably tune the catalytic material composition and size during the production of CNTs using this technique. This relies on existing knowledge of advances in the gas-phase synthesis of CNTs applied to this electrochemical system, where it is known that iron is the most catalytically active catalyst material, and that catalyst nanoparticle size controls the diameter of the grown CNTs. We show the ability to engineer the material composition of the electrodes to produce high yield (> 99%) growth of multi-walled CNTs with tight diameter ranges averaged < 30 nm, and we show that control on catalytic nanoparticle size can decrease this average diameter to even smaller CNTs. Most notably, early results indicate a minority presence of few-walled and single-walled CNTs, and we present a vision where the ability to transfer the mechanisms studied and understood for single-walled CNT growth over the past few decades can drive rapid forward progress in producing high quality single-walled CNTs in both tangled and aligned architectures using this technique. This paves a pathway to produce a material that prominent researchers for the past few decades have envisioned to revolutionize our modern world, with a precursor material derived from air that poses a significant long-term global threat to mankind.

References:

[1] B.B.M.D. Ingram and G.J. Janz, Electrochim Acta, 11, 1629 (1966)

[2] H.Y. Yin, X.H. Mao, D.Y. Tang, W. Xiao, L.R. Xing, H. Zhu, D.H. Wang, and D.R. Sadoway, Energ Environ Sci, 6, 1538 (2013).

[3] S. Licht, A. Douglas, J. Ren, R. Carter, M. Lefler, and C.L. Pint, ACS Cent Sci, 2, 162-168 (2016).
(Invited) Functionalization of Carbon Nanotubes
Authors: Billups W. E.
Published: February 2020

Reductive alkylation of SWNTs using lithium and alkyl halides in liquid ammonia was found to yield sidewall functionalized nanotubes that are soluble in common organic solvents. Atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM) of dodecylated SWNTs prepared from HiPco nanotubes show that extensive debundling has occurred. SWNTs functionalized by dodecyl groups can be used for length measurements by atomic force microscopy. Different thermal behavior of the dodecylated SWNTs was observed when the reductive alkylation was carried using either sodium or potassium. Solid state 13C NMR spectroscopy indicates that the product derived using sodium may have a higher proportion of 1,4- than 1,2-addition of the alkyl groups. 1,4-Addition products are expected to exhibit greater thermal stability. SWNTs functionalized by phenyl groups can be sulfonated in oleum (H2SO4, 20% free SO3) to give material that exhibits high solubility in water. Cytotoxicity studies show that SWNTs with a high degree of sidewall functionalization are not toxic to skin cells.
(Invited) Multifunctional Materials from Dispersions of Single-Walled Carbon Nanotubes and Biomolecules
Authors: Davis Virginia A.
Published: February 2020

Dispersions of single-walled carbon nanotubes (SWNT) and biological molecules can enable multifunctional materials that combine SWNTs’ intrinsic mechanical and/or electrical properties with the properties of the biomolecule. For example, functionalization of SWNT and organic phosphate hydrolase can be used for pesticide detection, and dispersions of SWNT and laccase can be used to make anodes for electrochemical fuel cells. Some of the most intriguing biological SWNT dispersants are double stranded DNA (dsDNA) and enzymes and protein digests containing tryptophan residues. For example, dilute dispersions of dsDNA/SWNT and lysozyme/SWNT have been used to produce conductive antimicrobial films using layer-by layer assembly. Higher concentration dsDNA/SWNT dispersions form either cholesteric or nematic liquid crystalline phases which can be processed into tightly packed aligned films with controlled optical properties. Higher concentration lysozyme/SWNT dispersions can be used to produce mechanically robust antimicrobial films and properties. Finally, dispersion of SWNT in tryptic soy broth (TSB) containing casein digest has recently been shown to enable direct investigation of SWNTs’ microbiological properties in standard biological growth media.
Quantitative Analysis of Aqueous Two Phase Separation of DNA-SWCNT Hybrids
Authors: Yang Yoona , Shankar Akshaya , Aryaksama Thibault , Zheng Ming , Jagota Anand
Published: February 2020

Carbon nanotubes have attracted considerable interest due to their outstanding physical, electronical and optical properties. Since those properties depends on the chirality, sorting single walled carbon nanotubes (SWCNT) by chirality is essential. Hybrids of DNA and SWCNTs have been used successfully to solve tje long-standing recalcitrant problem of structure-based sorting of complex mixtures of SWCNTs. Recently, it is shown that single stranded DNA coated SWCNTs could be separated effectively into various chiralities using an aqueous two phase system. SWCNT partition in the ATP system is determined by the SWCNT solvation energy difference between the two phases. In this way, we suggest that the ATP process is both a technique for separation and a method by which to evaluate and rank hydration or solvation free energy. In this study, we performed a systematic study of various DNA sequences on different species of SWCNT in ATP systems of two different polymer composition. We observe strong sequence-dependent of partitioning. We developed a model that can phenomenologically describe the experimental observation well and be used to extract a quantitative measure of relative solvation free energy of various DNA/SWCNT hybrids. Furthermore, to investigate a structural basis for experimental findings, we have employed molecular dynamics to examine a few of the ssDNA/CNT combinations.
Multi-Modal Spectroscopic and Microscopic Characterization of Thin-Film Networks of Semiconducting Carbon Nanotubes
Authors: Jones Andrew Crandall , Kearns Nicholas M , McDonough Thomas J , Zanni Martin
Published: February 2020

Thin-film distributions of semi-conducting carbon nanotubes (CNTs) exhibit potential as a candidate material for photovoltaic devices due to their strong absorption throughout the solar spectrum and exceptional transport properties. Despite this potential, characterization of the systemic parameters which determine and limit photovoltaic performance has remained a challenge. To this end, multidimensional spectroscopic methods represent a valuable tool in identifying and describing the energetic pathways in these systems which contribute to device performance.

In this presentation, we demonstrate the development of a broad bandwidth (500-1300 nm), high-repetition rate (100 kHz) 2-dimenstional electronic spectroscopy (2D-ES) system capable of high-speed, low noise spectroscopic characterization of the energy transfer pathways. The diagonal and cross-peaks measured in 2D-ES measurements provide critical information about the dephasing time, correlation, and couplings between electronic states. The high acquisition rate of our measurement system enables us to monitor multiple detection pathways, limited not only to optical absorption, but also measurement of the photo-induced current allowing for direct spectroscopic characterization of the energy pathways taken by carriers contributing to photocurrents.

In addition to traditional far-field spectroscopic characterization, in which the response of a macroscopic area (10's of μm2) is collected, we further show the use of our broadband source in microscopic spatial mapping of device response. Through combination with atomic force microscopy of the nanoscopic structure of a surface, we demonstrate the ability to characterize and correlate the topology of a surface with a specific optical response.
Unique Architectural Fidelity of C60-Decorated Flavin-Wrapped Nanotubes
Authors: Papadimitrakopoulos Fotios , Karunaratne Erandika , Mollahoseini Mehdi , Gascon Jose
Published: February 2020

One of the greatest challenges with single-walled carbon nanotube (SWNT) photovoltaics and nanostructured devices is maintaining the nanotubes in their pristine state (i.e. devoid of aggregation and inhomogeneous doping) so that their unique spectroscopic and transport characteristics are preserved. To this effect, the tight helical wrapping of flavin derivatives around SWNTs presents an ideal vehicle for individualizing SWNTs, while at the same time affording the incorporation a variety of substituents that can be brought within π-π overlap to the graphene sidewalls (Figure 1a). C60-functionalized flavin composed of PCBM and isoalloxazine moieties attached on either ends of a linear, C-12 aliphatic spacer forms a concentric assembly where transient absorption spectroscopy have shown the effective photoinduced charge transfer quenching of the encased SWNTs. In this contribution, we present convincing evidence on the exact location where the C60 moiety resides. As shown before1, the isoalloxazine helix is partitioned into a co-spiral electronegative uracil groove (Figure 1b) and an electropositive o-dimethylphenyl (phenyl) groove (Figure 1c). Spectroscopic investigation alongside with modeling of the diameter-dependence ES
ii
redshifts suggests that the C60 moiety is solely localized within the uracil grooves (Figure 1b) due to improved electrostatic interactions. This indicates the profound assembly fidelity of FMN-wrapped nanotubes, which rivals that of biological helices.

1 M. Mollahosseini, E. Karunaratne, G. N. Gibson, J. A. Gascón, F. Papadimitrakopoulos, "Fullerene-Assisted Photoinduced Charge Transfer of Single-Walled Carbon Nanotubes through a Flavin Helix", J. Am. Chem. Soc.
2016, 138, 5904−5915.

Figure 1
(Invited) Optical and Electrical Generation of Exciton-Polaritons in Single-Walled Carbon Nanotubes
Authors: Zaumseil Jana
Published: February 2020

Exciton-polaritons are quasiparticles that form upon strong coupling between electronic excitations of a material and photonic states of a surrounding microcavity. In semiconducting single-walled carbon nanotubes the special nature of excited states leads to particularly strong coupling even at room temperature (Nature Comm. 2016, 7, 13078). While emission from exciton-polaritons is usually created by optical excitation, the high ambipolar charge carrier mobilities of single-walled carbon nanotubes make them suitable for electrically driven polariton light-emitting devices with extended functionalities. We show that strong coupling and near-infrared exciton-polaritons can be generated and tuned in light-emitting field-effect transistors with integrated microcavities.
(Invited) Design and Engineering of Interfaces/Interphases for Stable Li Alloy Anodes
Authors: Wang Donghai
Published: February 2020

Li-alloy based anode materials are one of the most promising anodes for next-generation Li-ion batteries. The poor interfacial stability (unstable solid-electrolyte interphase (SEI)) in the battery has been the primary issue hindering their practical application. In this talk, I will present a strategy that introducing multiple functional components bonded to the Li-alloy material surface into the SEI to reinforce the SEI with desired properties including good tolerance to the Li-alloy material volume change and efficient surface passivation against electrolyte penetration. The SEI reinforced by this strategy shows much better stability than the SEI reinforced by electrolyte additive strategy, which is the current state-of-art and commercially used solution to SEI stability issue.
5Wh Class Planar Sodium Nickel Chloride (Na-NiCl2) Battery Operated at below 200oc for Grid Scale Energy Storage
Authors: Jung Keeyoung , Park Yoon-Cheol , Son Sori , Lee Younki , Kim Chang-Soo , Jin Dana , Shim Wooyoung , Chang Hee Jung , Li Guosheng , Sprenkle Vincent
Published: February 2020

Sodium nickel chloride (Na/NiCl2) battery is one of the most promising candidates as a large scale electrochemical energy storage device. The battery comprises molten Na and NiCl2 as negative and positive electrodes, respectively, in its charged state, separating them by a β”-Al2O3 solid electrolyte (BASE). In order to facilitate fast sodium ion transport in the cathode compartment, molten NaAlCl4, as a secondary electrolyte (or catholyte), is infiltrated into the cathode materials powder. The battery typically operates at 250~300oC so as to maximize the ionic flux in the NaAlCl4 and through the solid electrolyte, and to minimize the dissolution of NiCl2into the melt. However, this efficient battery is yet to be widely used in grid scale energy storage applications since it is still expensive and hard to dramatically reduce the cell price mainly due to its use of expensive sealing technologies.

The presentation introduces Korea-US collaborative efforts to develop a lower temperature operating sodium beta-alumina battery (LT-NBB) with a Na/NiCl2 chemistry. Since the novel battery runs at below 200oC, it can be fabricated at an ultra low manufacturing cost by introducing a new planar cell design with a greatly reduced number of cell components, and by eliminating expensive conventional sealing technologies. Enhanced degradation resistance of cathode materials is another important advantage of this technology. In this presentation, challenges and progress in building 5Wh class prototype LT-NBB cells using BASE with 70 mm in diameter will be discussed.

Figure 1
Electrochemical Reaction and Direct Energy Conversion of Macroalgae Biomasses By Functional Nanomaterial Modified Electrodes
Authors: VU Huong THI , Yoshikawa Hiroyuki , Tran Duc Minh , Toake Hitoshi , Tamiya Eiichi
Published: February 2020

Biomass extracted from brown macro-algae promises as a future renewable energy because of non-toxicity, natural availability, and greenhouse gas free and do not interfere with the human food chain. Here, we first show the extraction of energy from brown macro-algae by via direct oxidation of macro-algae biomasses by using the novel materials combination of gold nanoparticles (AuNPs), titania (TiO2) and functionalized multi-walled carbon nanotubes (f-MWCNTs). The catalytic activity for macro-algae biomasses oxidation of composites materials was tested by both of cyclic voltammetry and chronoamperometry methods. In all experiments, TiO2/Au/CNT nanocomposites exhibited better electrochemical performance than TiO2/CNT composites; AuNPs/CNT composite or CNTs only. Enhanced current response can be attributed to the synergic effect of nano-TiO2, nano-Au and f-MWCNTs. Furthermore, the new materials showed improvement on both direct fucose and alginate fuel cell performance. The results from this research open possibility for practical application of our fuel cell by using the cheap catalytic material of TiO2 with high efficiency on conversion of energy from brown macroalgae biomass.

Figure 1
(Corrosion Division Morris Cohen Graduate Student Award Address) Novel Insights into the Corrosion of Magnesium Alloys
Authors: Esmaily Mohsen , Svensson Jan-Erik , Johansson Lars-Gunnar
Published: February 2020

It is becoming increasingly evident that lightweight technology is vital for reducing demand on limited natural resources and to combat global warming. Thus, there is currently a growing interest in magnesium (Mg) and its alloys since they are the lightest structural metallic materials and can enable the design of lighter engineering solutions. Efforts are underway to replace iron-based alloys with Mg-based alloys. Still, the use of Mg-based alloys is restricted by a number of inherent limitations, including inherent vulnerability to environmental degradation, poor formability, low creep resistance and unstable price. However, with the latest breakthroughs in Mg technology, these major drawbacks are being gradually overcome. One solution to solve the corrosion issue in Mg alloys has been shown to be alloy development through controlling the solidification. Our efforts in developing a quantitative description of the alloys’ microstructure and the alloys’ corrosion behavior have now reached an interesting stage; the newly designed cast Mg alloys AZ91 and AM50 exhibit significantly better corrosion resistance than their commercial counterparts. This is achieved a through a fundamental understanding of the interplay between microstructural constituents and the Mg alloys’ corrosion process. We show that changing the alloy microstructure, with no new addition of alloying elements as compared to existing commercial alloys and no significant change in the manufacturing, improves the alloys’ corrosion resistance. In this presentation, we discuss the research strategy (from micron to nanometer scales) that results in an improvement in the corrosion behavior of Mg alloys. Besides, some previously unrecognized concepts in Mg corrosion phenomenon are also presented. We believe that the ideas presented here are generic and can be employed for other light alloys, when corrosion is an issue.
Effect of Artificial Seawater on Passivation of Ti
Authors: Yan Shaokun , Song Guang-Ling , Zheng Dajiang , Dargusch Matthew , Zhou Lian
Published: February 2020

Titanium is well known for its high corrosion resistance. It may be used in the marine industry. In this study, the passivation behavior of titanium was investigated in artificial seawater. It was found that some anions in the artificial seawater could influence the passivation current densities of Ti. The anodic current peak at around 1.6V/SCE on the passivation curve could be associated with dissolution of the passive film. Oxygen evolution could occur at an even more positive potential. The surface films formed at different potentials exibited different biofouling performance.
The Mixed Potential Model for the Passive State and Hydrogen Evolution Reaction of AA2098-T851
Authors: Macdonald Digby D. , Ghanbari Elmira , Saatchi Alireza
Published: February 2020

Theoretical and experimental investigations for fundamental understanding of the passivation process and its kinetics could lead to the prediction of the electrochemical behavior of the third-generation Al-Li alloy 2098. In this paper, the kinetics of the passive film formation on AA2098-T851 in 0.1M NaHCO3 in a CO2 atmosphere at 25°C, at potentials with both metal dissolution and hydrogen evolution reaction (HER) was investigated. This was done by performing electrochemical impedance spectroscopy (EIS) on the passive layer after each potentiostic steps in the anodic direction that followed by stepping in the opposite direction. The optimization of the EIS data was done by applying the previously developed Mixed Potential Model (MPM) that considers the Point Defect Model (PDM) for dissolution and passivation of the metal along with the Butler-Volmer equation for the cathodic reaction. It was shown that the inequality of certain kinetic processes of passive layer formation leads to the irreversibility of the metallic passivation in opposite potential scanning directions. Also, considering that the hydrogen evolution reaction incorporates quantum mechanical tunneling of the charge carriers through the barrier oxide layer on the passive metal surface, a cathodic Tafel constant (βc
) was calculated. The estimated βc
was in accord with the predicted value for the HER according to the slow discharge of protons mechanism.
(Invited) Past, Present, and Future of High-k/Metal Gate Technologies
Authors: Iwai Hiroshi
Published: February 2020

The SiO2 based gate insulator and poly Si gate electrode had been used almost 4o years for (C)MOS integrated circuits from 1970 to 2010 because of their extraordinary good properties of both the interfaces at the substrate and gate electrode. Thus, most of the people had not believed the replacement of SiO2/poly Si gate stack by that of high-k/metal in the products would be impossible, although the demand to introduce the high-k gate oxide became stronger due to the high tunneling gate leakage current when decreasing the gate oxide thickness with the scaling. However, the operation of high k/metal gate stack MOSFETs were demonstrated by several different organizations at the same time at IEDM 1999. Since then, many R & D organizations seriously participated to the research and development of high-k/metal gate stack for MOSFETs. It was in 2001, when Prof. Samares Kar proposed to create an ECS symposium on “Physics and Technology of High-k Gate Dielectrics”. Then, the 1st symposium was held in Salt Lake City, Utah, U.S.A. on October 20-14, 2002. At that time total number of the presentations at the symposium was 34. The, number increased to 56 in the 2nd symposium in Cancun, Mexico, 2003, and 75, in the 3rd symposium in Los Angeles, in 2006, and so on. In 2007, Intel introduces HfO2 based high-kmaterial for the 1st time into their product. Later, the symposium was renamed with Semiconductors, dielectrics and metals for Nanoelectronics and still continues and contributed to give opportunities to the researchers and engineers for the paper presentation and discussion. Prof. Samares Kar has been the leading organizer of the symposium, maintaining rigorous standards to make the symposium one of the most successful in ECS. However, it was very sad that Prof. Samares Kar passed away on January 13, 2017 at his home in Kolkata, India. We would like to express our sincere appreciation for the hard work and rigorous drive towards the advancement of the symposium by giving presentations for the past, present and future of high-k stack technologies.
(Invited) Interface Engineering for Nanoelectronics
Authors: Hacker Christina A. , Bruce Robert C , Pookpanratana Sujitra
Published: February 2020

The pace of innovation within the electronics industry is picking up steam in response to critical challenges as conventional silicon technology matures. Increasingly, semiconductor-based systems, from small sensors to high performance computers, or everything in between, must maximize performance, while minimizing energy use and providing security and assurance. As recently highlighted in “Semiconductor Research Opportunities” by the SIA/SRC, for the semiconductor industry to continue achieving performance improvements, the broader research community needs a comprehensive approach that considers all aspects of semiconductor technology, including novel materials, new manufacturing techniques, new structures, system architectures and applications.

Among these approaches is the fundamental understanding of electronic processes at interfaces since the interface increasingly dominates electronic performance. I will describe advances made in our ability to manipulate and measure organic and molecular interfaces at the nanometer scale and the impact on the resulting electronic performance. This talk will contain three primary themes, 1-designer interfaces, 2-electronic junction formation, and 3-advancing metrology for nanoelectronics. The foremost step of interface engineering is the ability to create designer surfaces where monolayers can be tailored for specific electronic properties. This can be achieved by controlling the tunnel barrier thickness on a ferromagnetic electrode or by using click chemistry to create dense, high-quality electrically active molecular layers. Understanding the electrical response on the nanoscale is non-trivial as often creating the test structure creates artifacts that dominate the electronic response. In particular, I will focus on the measurement advances made in molecular electronics, highlighting our understanding of the interface science and characterization.
Hole-Doping Induced Ferromagnetism in Monolayer SnO: A First-Principles Study
Authors: Houssa Michel , Iordanidou Konstantina , Pourtois Geoffrey , Afanas'ev Valery V , Stesmans Andre
Published: February 2020

Two dimensional (2D) materials are currently attracting considerable interest due to their promising applications in future nanoelectronic devices. Magnetic 2D materials are also gaining attention, for their possible use in novel spintronic devices [1]. Recently, hole-doping in monolayer SnO has been theoretically predicted to induce a paramagnetic to ferromagnetic phase transition in this 2D material, for a typical hole density of about 5x1013/cm2 [2]. Magnetism in monolayer SnO arises from an exchange splitting of electronic states at the top of the valence band, where the density of states exhibits a sharp van Hove singularity, resulting in a so-called Stoner (magnetic) instability [2]. This behavior is typical of materials with “Mexican-hat” energy band edges (as predicted for the valence band edge of monolayer SnO), and has also been predicted in e.g. monolayer GaSe [3].

In this work, the possibility to induce hole doping in monolayer SnO by intrinsic and extrinsic defects is investigated, using first-principles simulations, based on density functional theory. It is found that Sn vacancies generate spin-polarized gap states near the valence band edge of monolayer SnO, and that these point defects are behaving like acceptors. A typical density of 5x1013/cm2 of Sn vacancies induces a paramagnetic to ferromagnetic phase transition in the material, with a magnetic moment density of 1 Bohr magneton/hole. Substitutional doping of Sn atoms by e.g. In or Zn atoms is also predicted to result in hole-doping of monolayer SnO, and also leads to a ferromagnetic order in the 2D material. The possibility to induce a ferromagnetic phase transition in monolayer SnO by electrostatic doping will also be discussed.

[1] W. Han, APL Mater. 4, 032401 (2016).

[2] L. Seixas et al., Phys. Rev. Lett. 116, 206803 (2016).

[3] T. Cao et al., Phys. Rev. Lett. 114, 236602 (2015).
(Invited) Microcalorimetric Investigation of Cu Underpotential and Bulk Deposition – a Direct Access to Anionic Side Processes and Reaction Steps
Authors: Schuster Rolf , Frittmann Stefan
Published: February 2020

Measuring the heat during electrochemical reactions provides direct information on the reaction entropy of the electrochemical processes. These include also charge neutral side processes, e.g., coadsorption of anions with metal ions or ordering processes of the solvent at the interface, which will not show up in the electrochemical charge balance. Electrochemical microcalorimetry hence provides complementary information to the current voltage relationship as measured by conventional electrochemical techniques and may allow for the identification of side processes often obscured in electrochemical systems (1, 2). In this presentation we will present two examples, i) we will investigate anionic side processes during the Cu UPD formation on Au(111) in the presence of sulfate (3) and ii) we will address the reaction steps and the role of Cu+during the Cu-bulk deposition.

For Cu UPD it is well accepted that Cu deposition is accompanied by strong coadsorption of anions. From the course of the reaction entropy and the charge balance during the UPD process we determined the potential dependent anion coverages. From experiments with pH variation it followed that sulfate and bisulfate become adsorbed with roughly equal amounts. In addition we found highly positive reaction entropy upon the completion of the first metal monolayer, which signals a charge neutral substitution process of adsorbed anions by oxygenated species.

During pulsed Cu-bulk deposition we found that the heat evolution continues after the current pulse, i.e., without external current flow (see figure). This directly signals Cu deposition from Cu+ followed by a slow reestablishment of the Cu+/Cu2+ equilibrium, in agreement with the reaction mechanism of Mattsson and Bockris, proposed on the basis of the Tafel plot (4).

References:

1. S. Frittmann, V. Halka, C. Jaramillo and R. Schuster, Rev. Sci.
Instrum., 86, 064102 (2015).

2. S. Frittmann, V. Halka and R. Schuster, Angew. Chem. Int. Ed., 55, 4688 (2016).

3. S. Frittmann and R. Schuster, The Journal of Physical Chemistry C, 120, 21522 (2016).

4. E. Mattsson and J. O. M. Bockris, Transactions of the Faraday Society, 55, 1586 (1959).

Figure 1