bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas-Reduction—Nitridation Synthesis of Nitride Phosphors for Solid-State Lighting
Authors: Suehiro Takayuki , Xie Rong-Jun , Hirosaki Naoto
Published: February 2020

In the last decade, SiAlONs and nitridosilicates have been developed as an important class of phosphor host materials because of their great potentials for solid-state lighting (SSL). However, their low manufacturability (reaction sintering and postsynthesis grinding) is a major obstacle to the widespread use in SSL applications, triggering the intense investigations for developing more sophisticated processing techniques.

In this regard, we have developed the gas-reduction—nitridation (GRN) method, which enables the direct synthesis of nitride fine powders from the multicomponent oxide systems by using an NH3—CH4 gas mixture as a reduction—nitridation agent. The GRN-derived powders possess high phase purity, nonaggregated fine particle morphology, and very low impurity absorption throughout emissive regions, all of which meet the demands for phosphor applications. In this talk, our successful applications of the GRN process to the Eu2+-activated α-SiAlON and CASN, as well as Ce3+-activated La—Si—N phosphors for SSL will be demonstrated.
Transient Electroluminescence Measurement on Organic Light-Emitting Diodes (OLED) of Mutilayer Electron-Injection Structure
Authors: Gao Chia-Yuan , Chen Ying-Chung , Chou Dei-Wei , Chen Chern-Hwa , Huang Chien-Jung
Published: February 2020

The influence of electron-injection structure of cesium carbonate/silver nanocluster/cesium carbonate (CSC) is investigated in this study. The silver nanoclusters (SNCs) are introduced between the cesium carbonate electron-injection layers. When the CSC electron-injection structure replaces the cesium carbonate electron-injection layer of the single layer, the shorter response time and rising time are obtained by measuring transient electroluminescence. In addition, the maximum luminance for the device with CSC electron-injection structure is enhanced by 93% compared with that of the device with cesium carbonate electron-injection layer of the single layer because the electron-injection barrier between the cathode and the electron-transporting layer can be remarkably reduced. Moreover, the localized electric field around the SNCs is enhanced, resulting in an increase in electron injection from the cathode electrode.
Microelectrochemical Properties of Ti(C,N) Inclusion of High Strength Martensitic Carbon Steel
Authors: Watanabe Yuta , Muto Izumi , Ohmura Tomohiko , Hara Nobuyoshi , Sugawara Yu
Published: February 2020

High strength carbon steels are anticipated to be used in various fields. However, hydrogen embrittlement is always a big problem for high strength steels.As a result of several treatments to strengthen steel Ti(C,N) inclusions form. Although lots of reports have been conducted to in-steel inclusions such as MnS, little is known about Ti(C,N). Therefore the objective of this study is to look in to the microelectrochemial properties of Ti(C,N) inclusions and its effect on hydrogen embrittlement.

Titanium added carbon steel(0.24%C, 1.09%Mn, 0.003%S, 0.03%Ni, 0.16%Cr, 0.028% Ti, 0.031% N) was used as a specimen. The specimen was heat–treated at 1163K for 45minutes and then water-quenched. After that the specimen was kept at 493K for 1hr, and tempered. The specimen was mechanically polished with 1mm diamond paste. Electrochemical measurements were performed in a mixture of 50mM CH3COOH-50mM CH3COONa under naturally aerated conditions. The concentration of the solution above was adjusted to achieve maximum electrical conductivity, and its pH was 4.64.

The first step conducted was inclusion characterization. By searching the specimen surface with a SEM, Ti(C,N) inclusions were found to be several micrometers long and several micrometers wide. The color of the inclusion was found to be a red-pinkish color. The color of the inclusion varies from a bright color to a dim color depending on the chemical composition of the inclusion. Basically the more Ti composition the brighter the color is. Compared to a MnS inclusion Ti(C,N) inclusions are hard and are not affected by rolling.

Macroscopic polarizations were conducted to determine the macroscopic corrosion behavior of the specimen. Under weak acid conditions the specimen showed an active dissolution as soon as it was anodically polarized. On the other hand, cathodic polarizations showed the potential at which hydrogen started to form. (Fig. 1) This potential is important for determining the effect of Ti(C,N) on hydrogen embrittlement.

Microscopic polarizations were conducted to elucidate the electrochemical behavior of Ti(C,N) inclusions. Fig. 2 shows the cathodic polarizations curves of areas around Ti(C,N) inclusions and matrix areas that do not have inclusions in the target area. By comparing the open circuit potentials of the two curves we can see that areas around Ti(C,N) shows a high open circuit potential. By taking into account the potential-pH diagram of Ti(C,N) (Fig. 3) we can confirm that Ti(C,N) inclusions show a stable region in a noble region. Since Ti(C,N) are stable in a high potential, Ti(C,N) are likely to act as preferential cathodic reaction site.
Study of a Biocathode Based on the Physical Immobilization of Crude-Extract with Laccase Activity for Oxygen Reduction
Authors: López-González Berenice , Ramírez-Ledesma María Guadalupe , Cuevas-Muñiz Francisco Mherande , Arana-Cuenca Ainhoa , Ledesma-García Janet , Arriaga Luis Gerardo
Published: February 2020

A biocathode based on the physical absorption on carbon surfaces of crude extract with laccase activity (ExLac) obtained of C. polyzona, a Mexican endemic fungus that uses barley straw as substrate, is prepared and evaluated toward oxygen reduction reaction. The biocathode electrode consists in a mixture of ExLac with 10 mM ABTS {2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)} diammonium salt and vulcan XC-72.

Electrochemical evaluation of the biocathode consisted of cyclic voltammetry CV and linear sweep voltammetry in a standard three-electrode glass cell containing a neutral aqueous media phosphate buffer solution (pH 7.4 near to blood pH) in the absence and presence of oxygen. The biocathode working electrode is constructed as follows: an ink of ExLac-ABTS/Vulcan is prepared by dispersion in deionized water and 5% Nafion solution in a ratio of 1:56:5 in a vortex and subsequently deposited onto a PVC chip and dried at room temperature.

The results showed that the biocathode catalyzes the oxygen reduction reaction better than the platinum in a neutral media in glucose presence. Further, the electrocatalyst activity of ExLac-ABTS/C is compared with that achieved by using of a biocathode prepared with commercial laccase.

One of the advantages of this type of bioelectrode array is the utilization of barley straw as a substrate in the crude extract production which is an inexpensive material that may be a good alternative for great-scale production.
Effect of Hydrogen Neutral Beam on the Growth of Nanocrystalline Silicon
Authors: Lee Dong Hyeok , Jang Jin Nyoung , Hong MunPyo
Published: February 2020

We have investigated the effect of hydrogen neutral beam(H-NB) on the nano-crystalline silicon (nc-Si) thin films using the neutral beam assisted chemical vapor deposition (NBaCVD) system. In traditional hydrogenated silicon deposition, the gas mixture ratio of hydrogen and silane (SiH4) controls the phase of the thin films, including that from hydrogenated amorphous silicon (a-Si:H) to microcrystalline silicon (μc-Si). However, poor migration of deposition precursor and the absence of nucleation sites cause silicon background to be amorphous in the early stage of growth. Conversely, The NBaCVD technology controls the energy of neutral particles (mainly hydrogen atoms) in the range of 0-300 eV to enhance the crystallinity during thin film deposition at low temperature (<80 °C). The growth mechanism of the nc-Si thin film by the NBaCVD process differs from that of the nc-Si by conventional PECVD. The nc-Si thin films crystal volume fraction increases rapidly and saturates near 80 % while the grain size becomes gradually larger in a range of 4~5.5 nm as the H-NB kinetic energy (reflector bias) increases. Because the nucleation and nc-grain growth should be initiated on the sub-layer surface due to assistance of the energetic H-NB particles, an incubation layer is eliminated effectively. The structural state was estimated by micro Raman spectroscopy. The microstructure was analyzed by field emission transmission electron microscopy (FE-TEM). Finally, the very low temperature processed nc-Si TFT show much improved stabilities against sever positive bias light stress (PBIS; Vg= 20 V, Vd= 1 V, 100 mW/cm2 Halogen Lamp) condition, while the field effect mobility was up to 3.2 cm2/Vs: threshold voltage shift was smaller than 1 V after 104sec under the PBIS conditions.
Determination of Methylparaben by Square Wave Voltammetry at Boron-Doped Diamond Electrode
Authors: Mendonça Camila Domingues , Machado Sergio Antonio Spinola
Published: February 2020

Parabens have been widely used as preservative in personal care products, foods and drugs. However, due to their endocrine disruption and carcinogenic possible action, the quantification of these pollutants in several matrices is necessary. In this way, the present work has as objective, the development of an electroanalytical methodology using square-wave technique. The target molecule is the methylparaben (MePa), which will be determined using the boron-doped diamond electrode (BDD) as the work electrode. Several operating conditions and voltammetric parameters were studied seeking greater efficiency of the technique. Under chosen conditions, the measurements were realized in an electrochemical cell containing Ag/AgCl as the reference system and a platinum foil as auxiliary electrode. Several electrolyte solutions were tested and the best results were obtained in 0.2 molL-1 phosphate buffer (pH 7.5). In such electrochemical cell, MePa showed a well-defined square wave voltammetric peak at a potential around 0.8 V, whose peak currents are linearly proportional to the MePa concentration in the electrolyte. Adequate linearity (0.9986), as shown in figure 1, in the range of 0.5 to 30 mgL-1, with limit of detection and quantification of 0.103 mgL-1 and 0.344 mgL-1, respectively, was found. The method was validated for the determination of MePa in a creek water sample, with low pollution content, obtained in Sao Carlos – SP county (S 21 59.670’ / W 047 54.183’). Spiked solutions of such water samples added to the buffer solution, showed recovery range between 68.40% a 106.15%, with a relative standard deviation (RSD) less than 6.8% (n=3). The method seemed to be sensitive to MePa and can be used for detection in others water samples. In future, we intended to use this method for detection of methylparaben in cosmetics creams.

Figure 1. Method calibration curve for determination of MePa. Concentrations: 0.5, 0.75, 1.0, 5.0, 10.0, 15.0, 20.0, 25.0, 30.0 mgL-1.
Superionic Conductivities in Li1.7Al0.3Ti1.7Si0.4P2.6O12 Made Using LF-FSP (Liquid- Feed Flame Spray Pyrolysis) Processing to Free Standing Thin Films
Authors: Yi Eongyu , Wang Weimin , Mohanty Som , Kieffer John , Tamaki Ryo , Laine Richard
Published: February 2020

Although ceramic materials with superionic conductivities (> 10-3 S/cm) have been reported for pellets or sheets, no such examples exist for thin films (< 100 µm). Also, almost all superionic conductivities are observed in materials produced by the glass-ceramic processing method. However, to convert glass-ceramic sheets (1-2 mm) to thin films (< 100 µm), they are ball-milled, tape cast, and sintered to give conductivities of > 10-4 S/cm. Alternately, similar conductivities (> 10-4 S/cm) have been obtained for thin films produced using powders derived from sol-gel processing. However, sol-gel processing requires calcining powders producing hard agglomerates that can only be eliminated using high-energy milling. We demonstrate here that liquid-feed flame spray pyrolysis (LF-FSP) processing provides non-agglomerated nanopowders that can be used immediately to tape cast. Li1+x+yAlxTi2-xSiyP3-yO12 (x = 0.1, 0.3/y = 0.2, 0.4) nanopowders were prepared by LF-FSP with a primary focus on the effects of Al0.3/Si0.4 doping on conductivities. Furthermore, the effects of excess Li2O on Al0.3/Si0.4 doped materials were studied. Li1.7Al0.3Ti1.7Si0.4P2.6O12 pellets sintered to 93-94 % of theoretical density and samples with varying excess Li2O contents all show superionic conductivities of 2-3×10-3 S/cm at room temperature. Li2O lowers both the crystallization temperatures and temperatures required to sinter. Total conductivities range from 2×10-3 to 5×10-2 S/cm in the temperature span of 25° to 125 °C. Small grain sizes of 600±200 nm were produced consistently. Initial attempts to make sturdy thin films gave films with thicknesses of 52±1 µm and conductivities of 3-5×10-4 S/cm at sintering temperatures of only 1000 °C; attributed to final densities of only ≈ 88 %. Thin films of LAGP materials where Ge substitutes for Ti of LATP, reported by other groups, show comparable conductivities but may not be suitable for mass production due to the high cost of Ge. Typical liquid electrolytes used today offer conductivities of 10-3-10-2 S/cm at room temperature and can tolerate temperatures ≈ 60 °C. Beyond this point, permanent damage is done to the battery due to electrolyte decomposition coincident with gas evolution. This, in turn, results in pressure build-up leading to mechanical damage within the battery pack, fire, or explosions in extreme cases. Replacement with the ceramic thin film electrolytes as developed here could offer much improved safety as they will be stable to much higher temperatures.
Thin Films and Superlattices in the Bi-Fe-O System Prepared by ALD
Authors: Akbashev Andrew R. , Spanier Jonathan E.
Published: February 2020

Bismuth ferrite (BiFeO3) is one of the most technologically promising multiferroics with a simple perovskite structure and high ferroelectric and antiferromagnetic ordering temperatures. High-quality heteroepitaxial growth of BiFeO3 thin films has been demonstrated mainly by PLD, MBE, RF sputtering and metal-organic chemical vapor deposition (MOCVD). While the first three techniques listed above require ultrahigh vacuum and thus are rather expensive, particularly when used on an industrial scale, MOCVD may serve as an appropriate deposition method for the device fabrication. However, as nanoelectronic device sizes shrink, the demand for a high-precision deposition of thin layers on high-aspect-ratio structures grows stronger. ALD simply does not encounter this obstacle and can produce atomically smooth coverage on structures with extremely high aspect ratio. We will discuss the growth of BiFeO3 thin films and (Bi-O)x(Fe-O)y superlattices by ALD and the influence of the growth parameters on the phase composition of the resulting films. In short, the preparation of the films involved two stages: the deposition of the amorphous films and superlattices on Si wafers, SrTiO3(001), Nb:SrTiO3(001) at 250 C and a subsequent annealing of as-deposited films at various temperatures. Using XRD analysis and TEM imaging the annealed BiFeO3 films were demonstrated to be highly crystalline; piezoresponse force microscopy showed an expected response of the ferroelectric phase. The ALD growth of BiFeO3 will provide a new way of convenient, technologically-oriented and commercially realizable deposition of a promising multiferroic for nanoelectronic devices.

This work was supported by the NSF DMR under 1124696 and by the ARO under W911.
Defect States in ALD-HfO2 Films on InP Compound Semiconductor as a Function of Film Thickness
Authors: Kang YuSeon , Kim DaeKyoung , Kang HangKyu , Cho Mann-Ho , Cho SangWan , Kim Hyoungsub
Published: February 2020

We investigated the chemical states and nature of the defect states below the conduction band edge of atomic-layer-deposition HfO2 grown on InP substrates as a function of film thickness. Changes in electronic structure of HfO2 film on InP (001) as a function of film thickness were investigated using high resolution x-ray photoelectron spectroscopy (HR-XPS) and x-ray absorption spectroscopy (XAS). OK
1-edge absroption spectra of the HfO2/InP showed the conduction band edge states in HfO2 were increased when the film thickness was increased. DFT calculations and conductance results indicated that these conduction band defect states were caused by the oxygen point vacancy in HfO2 related with Hf3+ states. Moreover, we found the mid-gap states within the InP band gap were caused by out-diffused InP substrate elements into the HfO2 film. By the combination analysis of XAS, XPS, DFT, and conductance, we conclude that (i) the conduction band edge defect states were resulted from the oxygen point vacancy into the HfO2 film, (ii) the mid-gap states within the InP band gap were resulted from the out-diffused P elements into HfO2 film near the HfO2/InP interface.
Investigation of Electrical Characterization of Hetero-Junctions Formed by RF Sputtered Indium Tin Oxide on Silicon
Authors: Saikumar Ashwin Kumar , Skaria Giji , Sundaram Kalpathy B
Published: February 2020

Certain oxide semiconductors show promise as wide-scale use in optical applications owing to their low electrical resistivity and high optical transparency. One such oxide taken into our consideration here is Indium Tin Oxide (ITO). ITO is one of the most commonly used transparent conducting oxides owing to its good optical transparency and low electrical resistivity. It is also relatively easy to deposit as thin films. When deposited upon silicon, Indium and tin oxide forms good hetero-junction photovoltaic cells.

In this work, we study the electrical properties of ITO-Si hetero-junctions prepared under various deposition parameters. For this investigation, we fabricate ITO-Si hetero-junctions by RF sputtering of ITO (90% In2O3 and 10% SnO2) target. Interestingly, ITO-Si hetero-junctions can be formed on both n- and p- type Si. The studies are performed on both hetero-junction devices of ITO sputtered on n- and p- type Si wafers and characterized.

REFERENCES

[1] J.B. DuBow, D.E. Burk, and J.R. Sites, “Efficient photovoltaic heterojunctions of indium tin oxide on silicon” Applied Physics Letters 29, 494 (1976)

[2] Tiberiu Mizrah and David Adler, “Indium-Tin Oxide-Silicon Heterojunction Photovoltaic Devices” IEEE Transactions on Electron Devices, Vol. ED-24, No. 4, April 1977

[3] J. Shewchun, D. Burk, R. Singh, M. Spitzer, and J. Dubow “The semiconductor-insulator-semiconductor (indium tin oxide on silicon) solar cell: Characteristics and loss mechanisms” Journal of Applied Physics 50, 6524 (1979)

[4] H. Kobayashi, T. Ishida, K. Nakamura, Y. Nakato and H. Tsubomura, “Properties of indium tin oxide films prepared by electron beam evaporation method in relation to characteristics of indium tin oxide/silicon oxide/silicon junction solar cells” Journal of Applied Physics 72, 5288 (1992)
Redox Nanocomposite Cathode Materials for Lithium Rechargeable Batteries
Authors: Jung Sung-Kyun , Kim Hyunchul , Park Kyu-Young , Kim Hyungsub , Lee Buyngju , Park Young-Uk , Kim Haegyeom , Yoon Won-Sub , Kang Kisuk
Published: February 2020

Only a small number of Li-containing cathode materials groups are considered for practical use in Li-ion battery systems. The possible candidates of cathode material were limited to the crystals that contain both redox-active element and lithium ion in the open framework. This concept has been conventionally considered as a standard for searching the cathode materials. But, it could be constraints to restrict the choices of materials for cathode in Li-ion battery systems. To expand the sight for seeking new positive electrode material, we suggested a novel strategy to use various kinds of Li-free transition metal ionic compounds (MX, M = transition metal, X = anion or polyanion group) as a positive electrode material by blending with a Li ionic compound (LiY, Y = anion or polyanion group) in nanoscale.[1] MX and LiY provided a redox couple and lithium ion supply for an electrochemical reaction. This concept is unconventional with general system of electrode material (Li ions and transition metal ions are in the same crystal system). In this case, transition metal ion and Li ion in the nanocomposite do not exist in the same crystal system and spatially separated as a mixture of MX and LiY.

In this paper, we will introduce and discuss about the transition metal oxide system as a redox couple among the infinite possible combinations of lithium ionic compounds and metal ionic compounds. Transition metal oxides such as FeO, MnO were considered as promising anode materials due to the earth abundance and large capacity from conversion reaction.[2] Although they have redox potential below 1 V as anode material,[3][4] we will show that this transition metal oxides can be applied to the cathode materials (3 V-class) by making nanocomposite with lithium ionic compound. To better understand the mechanisms during electrochemical cycling we have performed XPS, XANES/EXAFS analysis, allowing us to study the local environment change of Fe or Mn during the charge and discharge reaction. FeO and MnO showed different aspects during the electrochemical reaction in terms of electrochemical activity and local environment change. We will discuss about the reaction mechanism in detail.

[1] S.-W. Kim, K-Y. Nam, D.-H. Seo, J. Hong, H. Kim, H. Gwon, and K. Kang, Nano Today, 7, 168 (2012)

[2] P. Poizot, S. Laruelle, S. Grugeon, L. Dupont, and J.-M. Tarascon, Nature, 407, 496 (2000)

[3] M. Gao, P. Zhou, P. Wang, J. Wang, C. Liang, J. Zhang, and Y. Liu, J. Alloy. Compd., 565, 97 (2013)

[4] X. Li, D. Li, L. Qiao, X. Wang, X. Sun, P. Wang, and D. He, J. Mater. Chem., 22, 9189 (2012)
Lithium-Ion Transport at Electrolyte/Electrode Interface Visualized By Nanoscale Meniscus Cell Microscope
Authors: Kumatani Akichika , Takahashi Yasufumi , Inomata Hirotaka , Munakata Hirokazu , Ino Kosuke , Shiku Hitoshi , Kanamura Kiyoshi , Matsue Tomokazu
Published: February 2020

Towards the establishment of low-carbon emission society, one urgent issue is to standardize an efficient method to store unused energy. A promised candidate is an electrochemical storage such as lithium-ion batteries. However, it is still hindered as a major problem that the lithium-ion batteries do not conduct with sufficiently high energies capabilities and stable operational cycles. In particular, it is remained as an inefficient barrier of the lithium-ion (de)intercalation at the interface between electrode and electrolyte. It is therefore necessary to determine a crucial factor which influence to the homogeneity in ion transport across the interface by in-situ measurement with nanometer resolution.

In this study, the homogeneity in local ion transport of LiFePO4 thin electrodes is investigated by a nanoscale meniscus cell microscope (NMCM). It is a newly established scanning probe microscopy with a nano-size pipet with electrolyte and a reference-electrode.1 As the pipet is in proximity of the LiFePO4 electrode, a meniscus is created. Then, ionic current is only measured through the meniscus when the voltage is applied between reference and LiFePO4electrodes, as shown in Figure 1(a). When the pipet is scanned through the interface in nanometer step, a mapping of the ion current distribution in lithium (de)intercalation is obtained with topographical information in Figure 1 (b). Further, as the pipet was pinned at specific area, it allows us to study the localized ion transport by cyclic voltammetry or charge /discharge process. This new analytic technique will reveal a bottleneck of the ion transport in the materials. leading to the creation of electrode with homogeneous ion transport.

Reference:

(1) Y. Takahashi, et al., under review.
Imaging and Spectroscopy of Pristine and Cycled Li2MnO3
Authors: Phillips Patrick J , Iddir Hakim , Abraham Daniel P , Klie Robert F
Published: February 2020

Li-ion batteries have yet to reach their full application potential due to their inherent cycling performance issues, such as voltage instability and capacity fading, while fundamental questions remain unanswered regarding the mechanisms responsible. However, Mn-based layered oxides continue to be promising candidates for cathodes in high-energy-density Li batteries given their high voltage and high discharge capacities. A significant impediment to gaining insight into these layered oxides lies in their complexity and inhomogeneity. Thus, the focus of the present contribution will be on the parent material, Li2MnO3, which shows cycling characteristics similar to its more complex offspring. Scanning transmission electron microscopy (STEM) and spectroscopy are used to characterize structural and electronic properties of both pristine and cycled material.

STEM-based methods are quickly becoming the most promising characterization tools for these and similar materials, owed largely to the wide-range of techniques available on advanced STEM instruments, including the direct imaging of both heavy and light elements, and both energy-dispersive X-ray (EDX) and electron energy loss (EEL) spectroscopies. Imaging modes such as high/low angle annular dark field (H/LAADF) and annular bright field (ABF) are exploited to image heavy atomic columns, strain contrast, and light atomic columns, respectively. Additionally, electron energy loss spectroscopy along with calculations based on density functional theory are used to probe the local electronic structure by monitoring the O K- and Mn L-edges, which can be used to track changes to both the O content and the Mn valence. Thus, the focus will remain on the structural and electronic evolution of the pristine layered oxide explored by combining spectroscopy and atomic-scale imaging with various in situ microscopy techniques and ex situ electrochemical cycling. Specifically, features such as the atomic ordering of Mn/Li atoms, O vacancy evolution, and Mn valence will be of particular interest.
Studies of the Effect of Varying Prop-1-Ene-1,3-Sultone (PES) Concentration on Li-Ion Batteries
Authors: Nelson Kathlyne , Xia Jian , Dahn Jeff
Published: February 2020

Introduction

Electrolyte additives are the most effective way to improve the calendar life and cycling performance of lithium-ion batteries. Vinylene carbonate (VC) is perhaps the most well-known additive for Li-ion batteries and has been shown to be useful during the solid electrolyte interphase (SEI) formation [1], which can result in longer calendar life and reduced irreversible capacity (IRC). However, it has been shown that the performance of cells containing VC decreases at high temperatures and high voltages. Sulfur-containing additives have been studied in hopes to overcome the temperature sensitivity of VC. Prop-1-ene-1,3-sultone (PES) was found to have smaller IRC than VC-containing cells and was suggested to be an SEI forming additive [2]. In this study, we show that PES is a useful additive for Li-ion pouch cells and suggest that PES, when used in combination with other additives, may be more effective than VC at achieving long lifetimes and high cycling performance.

Experimental

Li[Ni1/3Mn1/3Co1/3]O2 (NMC)/graphite pouch cells made with 1M LiPF6in EC:EMC 3:7 (by weight) and varying amounts of PES were studied using ultra high precision coulometry and storage experiments. In addition, gas evolution measurements employing Archimedes principle and electrochemical impedance spectroscopy (EIS) measurements were performed. The PES-containing cells were compared to the same control electrolyte containing 2% VC.

Results

Figure 1 shows a preliminary set of results from both storage and cycling experiments of PES-containing cells compared with control electrolyte and 2% VC-containing cells. The dotted line in Figures 1a, d, and e indicates the value for 2% VC. Figure 1a shows the gas evolution during formation at 40°C and Figures 1b and c show gas evolution during storage at 60°C and 40°C, respectively. Cells containing 2, 4 and 6% PES show smaller gas during formation than that of 2% VC and all concentrations of PES studied show significantly smaller gas during 40°C and 60°C storage than VC-containing cells. The most prominent advantage of PES compared to VC is the extremely low gas evolution during high temperature storage. Figure 1d shows the voltage drop during storage from 4.2 V at 40°C for 500 hours. Figure 1e shows the average coloumbic inefficiency (CIE) during the last three cycles of cycling between 2.8 V and 4.2 V at C/20 and 40°C. Through the voltage drop and CIE, it is clear that 2% PES appears to be as good as 2% VC.

This work suggests that PES is a viable alternative to VC and is superior during high temperature storage. PES may also prove to be beneficial in combination with other additives.

References

[1] M. Broussely, Ph. Biensan, F. Bonhomme, Ph. Blanchard, S. Herreyre, K. Nechev and R.J. Staniewicz, J. Power Sources, 146, 90 (2005).

[2] B. Li, Y. Wang, H. Rong, Y. Wang, J. Liu, L. Xing, M. Xu and W. Li, J. Mater. Chem.
A, 1, 12954 (2013)
Use of Well-Aligned, Inclined Nanocolumnar Structured Cusi Thin Film As Anode Material in Lib
Authors: Polat Deniz Billur , Keles Ozgul
Published: February 2020

Oblique angle deposition method was used to fabricate inclined nanocolumnar structured CuSi thin films on Cu substrates. The reversible cyclability of those Si based composite anodes is greatly improved by optimizing the atomic ratio of Cu/Si in the thin films. The thicknesses, surface morphologies, and electrochemical behavior of the films deposited are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry (CV), impedance spectroscopy (EIS), and galvanostatic charge/discharge measurements. The galvanostatic test results show that the best result is achieved when the composite thin film having of 10%at. Cu- 90%at. Si is used as anode in half cell. It is possible to explain this remarkable performance by the amorphous structure of the thin film and its enhanced physical and mechanical properties due to the Cu content of the film. This study proves that electron beam evaporation can be an alternative method to fabricate electrodes used in lithium ion batteries, because this environmentally friendly process enables one to make production in one step without using any binders or conductive additives.
Synthesis and Crystal Structure of Lithium Iron Titanium Oxides Li1/2-+1/2xFe5/2-3/2xTixO4 with 0 ≤ x ≤ 1.666
Authors: Mukai Kazuhiko , Kato Yuichi , Horibuchi Kayo , Nakano Hideyuki
Published: February 2020

Li[Li1/3Ti5/3]O4 (LTO) is an ideal negative electrode material for long-cycle life lithium-ion battery (LIB), because of its “zero-strain” character [1]. In the LTO crystal lattice with Fd-3m space group, Li+ ions occupy both tetrahedral 8a and octahedral 16d sites, while Ti4+ ions sit the 16d site. We, thus, expect a solid solution compound Li1/2+1/2x
Fe5/2–3/2x
Ti
x
O4 (LFTO) between LTO and Fe[Li1/2Fe3/2]O4 via an intermediate spinel compound Li1/2Fe1/2[Li1/2Fe1/2Ti]O4. Fe[Li1/2Fe3/2]O4 is known to be one of the ferrites, which exhibit a soft ferromagnetic behavior. Here we report the results of powder X-ray diffraction (XRD) and electron diffraction (ED) measurements, and Raman spectroscopy analyses on the LFTO samples with 0 ≤ x ≤ 1.666.

According to XRD measurements, all the LFTO samples were assigned as a spinel-framework structure. For the x = 0 sample, the extra diffraction lines were clearly observed in addition to the normal diffraction lines in the Fd-3m. The extra diffraction lines are attributed to the superlattice diffraction lines due to the ordering between Li+ and Fe3+ ions at the octahedral site. As x increases from 0.25, such superlattice diffraction lines disappear, but, surprisingly, superlattice diffraction lines appear again at x > 1.2. The crystal structure at x £ 0.25 and 1.2 < x < 1.6 are assigned as the P4332 space group. Combining with the result of x dependence of cubic lattice parameter (a
c), the crystal structure of LFTO is classified into the four regions; (I) regular spinel structure of Fd3-m with x > 1.55, (II) superlattice spinel structure of P4332 with 1.2 ≤ x ≤ 1.55, (III) regular spinel structure of Fd3-m with 0.25 < x < 1.2, and (IV) superlattice spinel structure of P4332 with x ≤ 0.25.

Acknowledgement

This work was supported by Grant-in-Aid for Scientific Research (C), 25410207, MEXT, Japan.

References

[1] T. Ohzuku, A. Ueda, and N. Yamamoto, J. Electrochem. Soc., 142 (1995) 1431.
Significant Effects of Nitrogen Ion Implantation on Lithium Phosphorus Oxynitrid Solid State Electrolytes Via E-Beam Reactive Evaporation
Authors: Song H Z , Li Dejun
Published: February 2020

Microbattery devices are strongly equipped with onboard power systems which consists of one important component, that is, solid-state electrolytes. The solid-state electrolyte thin films used in microbatteries could be perfect and free pinholes to aviod short circuites. In this study, lithium phosphorous oxynitride(Lipon) thin film has been fabricated successfully by E-beam reactive evaporated sintering Li3PO4 with the insertion of nitrogen ions. Scanning Electronic Microscopy(SEM) showed that well-controlled film thickness and composition depend on the deposition parameter. Lipon thin films were examined by X-ray photoelectron spectroscopy (XPS), and the obtained results showed that the method of nitrogen ion implantation for the increase of nitrogen content in membrane is obvious and the decrease of the activation energy. Moreover, the lithium ion conductivity of the as-deposited Lipon thin films was investigated by impedance spectroscopy. It was found that the thin film exhibited high lithium ion conductivity. Due to three-coordinated nitrogen atoms, a higher cross-linked structure directly affects the ionic conductivity.
Investigation of Li-Ion Diffusion Rates Using Gitt in Cells with 3D Structured Intercalation Cathode Materials
Authors: Gotcu-Freis Petronela , Pfleging Wilhelm , Seifert Hans Jürgen
Published: February 2020

The public demand for high power energy storage systems is on a continuous ascending path. Efforts are directed towards the development of advanced lithium-ion electrodes, e.g. modified surface architectures. Direct laser patterning of thin and thick film electrode materials is a fairly new technical approach which enables an increase of capacity retention especially for high charging and discharging rates (Figure 1). It is assumed that an appropriate three dimensional surface topography influences the diffusion kinetics of Li-ions in the electrode materials through the electrolyte, whereas critical mechanical tensions during charging/discharging can be avoided and ohmic losses are significantly reduced inside the electrochemical cell.

The goal of this work was to enable quantitative studies of lithiation/delithiation rates which contribute to a better understanding of electrochemical intercalation/deintercalation processes in laser modified electrodes. The simplest quantitative approach to determine the rate of Li-ion insertion in the active material and the rate of Li-ion transport in the electrolyte is expressed by diffusion coefficient values. For this purpose, one of the most common coulometric titration technique, the galvanostatic intermittent titration technique (GITT) has been involved.

Electrochemical measurements were performed using the Swagelok® cell design for both, full and half-cell types, using graphite and metallic lithium as counter electrodes, respectively. The results of Li-ions diffusion rates are presented for laser structured and unstructured lithium -metal oxide cathode materials. The focus is set on composite thick film electrode materials containing binder, conductive carbon and layered intercalation lithium cobalt oxide (LiCoO2), which is the main cathode material used nowadays in many commercial lithium-ion cells. A main challenge for GITT was to evaluate suitable measurement parameters such as current pulse length, charge/discharge rate and relaxation time for each specific cell system. The results obtained were evaluated and compared to literature data.
Flower-like Co3O4 As an Anode Material for High Performance Li-Ion Batteries
Authors: Jadhav Harsharaj S. , Park Chan-Jin
Published: February 2020

The development of anode material with high specific capacity is the key issue in present lithium ion batteries (LIBs) technology. Recently, transition metal oxides have attracted much attention as an anode material for LIBs due to its high theoretical capacity (~700 mA h/g), long cycle life and high rate performances. Among various metal oxides, cobalt oxide (Co3O4) has been intensively investigated as a promising anode material for LIBs owing to its high theoretical capacity (890 mAh g-1), which is nearly two times higher than that delivered by conventional carbonaceous anodes. However, Co3O4 can suffer from poor cyclability and low rate capability, due to a large volume change and serious aggregation during charge/discharge cycling. Different proposals have been suggested to address this issue based on the tailored morphology, formation of nanocomposites with conductive additives and nano-size fabrication of Co3O4 electrode materials. In addition, various Co3O4 materials including nanotubes, nanorods, nanoneedles, nanospheres, platelets and nanowires have been synthesized and showed signiﬁcantly improved lithium ion storage properties compared to their bulk counterparts. In this study, the electrochemical properties of flower-like Co3O4 synthesized by simple urea-assisted chemical co-precipitation strategy with porous structure were investigated.

A facile urea-assisted template free, surfactant less chemical co-precipitation method and subsequent calcination (400-600 oC) for 2 h was pursued to obtain pure cobalt oxide (Co3O4) sample. The synthesized sample exhibited the cubic spinel structure and flower-like morphology. The obtained morphology is assembled by nanorods rising from common center, and the nanorods were comprised of interconnected particles with porous structure. The changes in the surface area and porosity of the flower like structure have been induced by manipulating the calcination temperature, resulting in significant impact on the electrochemical properties. Electrochemical investigation showed that the flower-like Co3O4 exhibited excellent cycling stability (1452 mA h g-1 at 0.5 C up to 300 cycles) and superior rate capability (reversible specific capacity of 880 mA h g-1 at 10 C). The obtained flower-like Co3O4 materials showed excellent cycle life and high rate capability, making it promising for applications in high-power LIBs.
Formation of Aligned Nanotubular TiSx Structures by Thermal Treatment of TiO2 in H2S
Authors: Kirchgeorg Robin , Hahn Robert , Schmuki P.
Published: February 2020

This talk will present the formation of highly aligned nanotubular TiSx electrodes consisting of self-organized TiO2 nanotubes formed by thermal heat treatment in H2S gas. Depending on the annealing time and temperature several mixtures of titanium oxy-sulfides can be formed. Even a complete transformation into TiS2 is possible under the right conditions. The formed TiSx layers show a slightly modified tubular structure compared to the original TiO2 nanotubes, but still offer a high surface area in form of tubular structure. The formed TiSx were characterized by SEM, XRD, XPS and tested regarding their battery performance as a cathode material for lithium ion batteries.

References concering high temperature treatments in reactive gas envoirment:

Y.-C. Nah, I. Paramasivam, R. Hahn, N. K Shrestha and P. Schmuki, Nanotechnology 21 (2010) 105704

R. Hahn, F. Schmidt-Stein, J. Salonen, S. Thiemann, Y. Song, J. Kunze, V.-P. Lehto and Patrik Schmuki, Angew. Chem. Int. Ed. 48 (2009) 7236 –7239
The Electrochemical Properties of Hyperbranched Polymer Nanocoated Cathode Materials
Authors: Lin Yueh-Wei , Wu Wei-Hsin , Tsai Li-Duan , Fang Jason
Published: February 2020

We introduce a novel type of surface nanostructured cathode materials. This approach relies on hyperbranched polymer beforehand directed nanoscale coating. The polymer coating successfully forms a uniform coverage onto the surface of the active materials. TEM photograph shows that lithium metal oxide particle is well decorated by polymer coating with 10 nm thickness.

Cycling performance (Figure 1) of modified electrode is comparing with pristine electrode at 1C charge rate with cut-off voltage 4.4V. Even after 300 cycles, the cells with modified electrode maintain at higher capacity level. On the other hand, the cells with pristine electrode quickly fade out.

These results demonstrate that the polymer coating effectively prevents the direct contact between electrodes and electrolytes that are highly vulnerable to electrochemical decomposition at high voltage conditions. Polymeric coating can also behave as interfacial protection layer that suppress the undesired interfacial reactions.
Tin Oxide Modifed LiNi0.8Co0.2O2 Cathode Material for Lithium-ION Batteries
Authors: Coban Huseyin Can , Keleş Özgül
Published: February 2020

Since the commercialization of lithium secondary batteries in the early of 1990s, their development has been rapid. It is a well known fact that lithium ion battery technology’s future depends on mostly improvements in electrode materials. Sol–gel production method is a promising way to prepare electrode materials due to their evident advantages over traditional methods, for example, homogeneous mixing at the atomic or molecular level, lower synthesis temperature, shorter heating time, better crystallinity, uniform particle distribution and smaller particle size at nanometer level. This study focused on the production of a cathode material ‘LiNi0.8Co0.2O2’ improved with a metal oxide ‘SnO2 surface modification’ for obtain improved cycling and better electrochemical performance lithium ion battery. ‘LiNi0.8Co0.2O2’ sub-micron sized powders are produced by using sol-gel production method, with using 3 different chealating agents ( citric acid, oxalic acid, adipic acid), various different calcination temperature (600, 700, 800, 900°C) and durations (5, 10, 15 hours). Following to that, by mechanical mixing and by using sol-gel technique, tin oxide modifcations with different molarities obtained on chosen powders. XRD and SEM analyses performed for obtained bare and modificated powders. These Powders with different characteristics laminated on alumunium foils with an automatic laminaton system and punched as a cathode material to use in coin cells. BET analysis, XRD and SEM studies showed that chealating agent and process parameters effect the powder crystallinity and morphology, and related to these specifications, electrochemical performance is directly effected. Electrochemical results also showed that, SnO2 modificated cathode materials (sol-gel modification) showed better cycle life and capacity retention (above 140mAh/gr) until 50 th cycle due to reducing the electrolyte–cathode interactions.
In-Situ X-Ray Imaging Study on the Cross-Sectional Distribution of Li-Ion Concentration in Electrolyte of Li-Ion Battery
Authors: Yamashige Hisao , Furuta Noritoshi , Mukouyama Masato , Kawamura Keiji , Ota Hisayoshi , Nonaka Takamasa , Kawaura Hiroyuki
Published: February 2020

In the previous studies, we observed the three-dimensional distribution of various Co-oxidation states in LiCoO2 (LCO) active materials. It was found that as a LCO electrode is charged, the surface of the electrode is preferentially oxidized than the inside area [1].

In this study, we researched the cross-sectional distribution of Li-ion concentration in the electrolyte of Li-ion battery by using an in-situ X-ray imaging method. In order to use this method we first created a special test cell, which models the cross-section of a positive electrode, separator, and negative electrode in a cell. While charging and discharging the cell, we observed how the cross-sectional distribution of Li-ion in the separator and negative electrode changed. Figure 1 illustrates the X-ray image of the cross section structure of the cell: the positive electrode, separator, and negative electrode and their interfaces. Figure 2 shows how the degree of X-ray transmission of the cross section changes before and 15 and 30-second after the cell is charged at 5C current. Before the cell was charged, the transmission degrees of the negative electrode and separator were the same, demonstrating that the Li-ion concentration was equally distributed across them. However, 15-second after the cell was charged, the transmission degrees in the negative electrode increased, and the degree of the electrode surface (the side close to the separator) became higher than that of the inside (the side close to the Cu collector). We expect that charging made the Li-ion concentration in the negative electrode decrease and the concentration of the surface became lower than that of the inside. As for analysis on the separator, the transmission degree on the negative electrode side of the separator became higher than that on the positive electrode side, demonstrating that the Li-ion concentration on the negative electrode side decreased after the cell was charged and that on the positive electrode side increased. Additionally, the concentration was more largely distributed 30-second after the cell was charged than 15-second after.

In summary, we succeeded in applying the in-situ X-ray imaging method for identifying the Li-ion distribution in the negative electrode and separator during charging.

References:

[1] H. Yamashige, et al. 52th Battery Symposium, Nagoya, 9th Nov 2010.
Wastewater Treatment for Water Recycling Using Microbial Fuel Cells
Authors: Bretschger Orianna
Published: February 2020

Microbial fuel cells (MFCs) have long been researched for their use as energy recovery devices during wastewater treatment. However, commercial applications of MFC systems have been challenged by high material costs and low energy recovery efficiencies. While energy densities remain low for these systems, recent work has demonstrated a reduction in capital costs, low biomass production, odor reduction, and accelerated treatment rates relative to conventional anaerobic systems. Here we describe a small pilot scale (100 gallon) anaerobic MFC system that is able to remove 88% of biological oxygen demand (BOD) and 80% of volatile suspended solids (VSS) from primary sludge in a 7 day residence time. A duplicate system was operated in parallel and held at open-circuit to determine what portion of BOD removal was associated with electrogenic activity as opposed to physical trapping or other mechanisms. The open-circuit system was only able to remove 45% of BOD and 38% of VSS in the same operational time frame. Under closed circuit conditions, operating with a 10 Ohm resistor, a maximum BOD removal rate of 1.09 kg-BOD/m3/day was achieved for primary sludge samples at ambient temperatures, while the open circuit condition showed a maximum BOD removal rate of 0.47 kg-BOD/m3/day. A coulombic efficiency of 13% was measured from the closed circuit system during maximum BOD removal. While system improvements are still required, these results represent significant progress toward the practical development of MFCs for municipal wastewater treatment and suggest that MFC technology may contribute toward realizing energy efficient water recycling. Acknowledgements: Funding for this project was provided by the California State PIER EISG program, NSF BBBE award 0933145, the Roddenberry Foundation, and the San Diego Foundation Blasker Science and Technology Award.