bluuebunny/crossref_metadata_2025_split huggingface dataset:
Li3V2(PO4)3 Particles Anchored in Carbon Nanofiber As a Cathode Material for High-Power Lithium Rechargeable Battery
Authors: Shin Jeongyim , Yang Junghoon , Kang Yong-Mook 
Published: February 2020

Lithium rechargeable battery has been rapidly developed for the applications in portable devices, electric vehicles (EV), and hybrid electric vehicles (HEV) due to their high energy density and durable cycle life. From the viewpoint of electrode, fast lithium ion and electron transport are essential to enhance its electrochemical performance. However, it is quite challenging to improve both properties at the same time, especially for cathode materials. Thus, no matter what we develop for new cathode materials, there have been severe limitations in terms of lithium ion diffusivity and electronic conductivity.
Phosphate (PO4)3--based materials have been attracting tremendous interests due to their competitive energy density and remarkable thermal stability. Among these phosphates, monoclinic Li3V2(PO4)3 (LVP) was proposed as a highly promising cathode material, owing to its high operating voltage and very high theoretical capacity of 197 mAh g-1 when all three lithium ions are extracted/inserted between 3.0 and 4.8 V. In particular, its three-dimensional structure framework consisting of slightly distorted VO6 octahedral and PO4 tetrahedral sharing oxygen vertex provides large interstitial space that makes lithium ions capable of moving fast inside the structure. However, just like the other metal phosphates, it shows a limited electron conductivity (10-8 - 10-9 S cm-1), which makes LVP to be difficult for practical applications.
Herein, we present a sagacious design of LVP/carbon nanofiber with a distinctive morphology where LVP nanoparticles are anchored in the surface of carbon nanofiber. In general carbon-coated LVP 1D materials, there has been a problem that the carbon coating layer additionally interferes with lithium ion diffusion into LVP bulk. However, in our structure, LVP particles can directly contact with electrolytes leading to an improved lithium ion conductivity. Furthermore, carbon nanofiber can provide fast electron transport along its 1D pathway. As a result, it was demonstrated that this unique structure is favorable for simultaneously maximizing Li ion conductivity and electronic conductivity for great electrochemical improvement of LVP materials.

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Electrochemical Performance of Ti- and Zr-Doped LiCoO2 Film Cathodes Prepared By Rf-Magnetron Sputtering for Lithium Microbatteries
Authors: Sivajee-Ganesh Kapu , Purusottam-Reddy Bommireddy , Hussain Obili M , Mauger Alain , Zaghib Karim , Julien Christian M 
Published: February 2020

In an attempt to enhance the microstructural and electrochemical (EC) properties, LiCoO2 thin films were doped with titanium or zirconium. RF magnetron sputtering technique has been employed for the deposition of films on Au/Ti/SiO2/Si substrates from lithium-rich LiCoO2 target with mosaic configuration. The as-deposited and Ti- and Zr-doped LiCoO2 thin films at lower doping concentration exhibited the α-NaFeO2 structure with R-3
m symmetry as confirm from X-ray diffraction and Raman studies. The cyclic voltammogram of micro-electrodes in aqueous electrolyte exhibited perfect redox peaks with good reversibility. The chronopotentiometry studies revealed that the discharge capacity of pure LiCoO2 was 64 µAh cm-2 µm-1, while 2% Ti- and Zr-doped films showed enhanced capacities 69 and 68 µAh cm-2 µm-1 (248 mC cm-2 µm-1, 245 mC cm-2 µm-1) respectively. The Zr-doped films exhibited good structural stability even after 25 cycles with the capacity retention of 95%. The kinetics of lithium ions in pure and Ti/Zr-doped LiCoO2 thin film cathodes and their cycleability are studied using both aqueous Pt//LiCoO2and and non-aqueous Li//LiCoO2 cells and the results will be presented.
Effects of Environmental Humidity on Self-Discharging Behaviour and Electrochemical Performance of Lithium-Ion Batteries
Authors: Byun Seoungwoo , Park Joonam , Appiah Williams Agyei , Park Jinkyu , Ryou Myung-Hyun , Lee Yong Min 
Published: February 2020

The application of lithium ion batteries (LIBs) have been widen from IT devices to electric vehicles (EVs). To be precise, EVs adopting LIBs are being increased because LIBs guarantee high energy density and cycle life. LIBs are also sensitive to external environmental factors such as temperature, humidity, vibration, etc. In order words, these conditions should be controlled for better battery performance and reliability. Most of the studies on LIBs have been focused on temperature as the key environmental factor, however, other variables such as humidity should be also considered carefully for EV application. Hence, this work focuses on the effect of humidity on self-discharging and battery degradation behaviour.
Herein, we try to unveil the effect of relative humidity on self-discharging behaviour of fully charged LIBs by monitoring open-circuit voltages (OCVs), capacity and power retention, and electrochemical impedance before and after storage. Pouch-type LIBs having LiNi1/3Co1/3Mn1/3O2/graphite chemistry are fabricated, and then stored at room temperature under high humidity condition (>90%). As a result, the OCV drop is much higher at high humidity condition, which causes more degradation of capacity and power than expected. This abnormal result will be discussed in more detail via various case studies and analysis.

References

1. R. Yazami and Y.F. Reynier, Electrochemica Acta, 47, 1217 (2002)
2. I. Bloom et al., Journal of Power Sources, 15, 238 (2001)

Acknowledgements

This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977).

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Coronene-Based Conductive and Ductile Polymer Binder for Lithium-Ion Batteries
Authors: Taskin Omer Suat , Yuca Neslihan , Cetintasoglu Mehmet Emre , Dogdu Murat Ferhat , Avci Ipek 
Published: February 2020

Lithium-ion batteries (LIP) are becoming more common in portable electronic devices due to their high energy density, lack of memory effect, and high charge and discharge rate capabilities. Li-ion batteries are a relatively new technology, first marketed in the early 1990s, and research and development work is ongoing to improve safety and increase capacity, charge/discharge rate, and lifetime.
In this work, the development of a synthetic process for the next generation of coronene-based polymeric binders with high conjugation and very ductile backbone structures along the chains was showed. The reaction proceeds through the free-radical polymerization of the acrylate backbone. The polymerization process does not require the transition metal catalyst and has relaxed requirements to the experimental condition.
In summary, a new type of side-chain electron-conducting polymer binder was developed and it showed the stable and high capacities at a C/3 cycle rate.

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The Effect of Polymer Binder on the Electrochemical Performance of Si/C Anodes
Authors: Terborg Lydia , Ling Min , Nie Kaiqi , Dahi Antoine , Wu Chenghao , Guo Jinghua , Ross Philip N , Liu Gao , Kostecki Robert 
Published: February 2020

Silicon with its theoretical capacity of 4200 mAh/g is an attractive alternative to graphitic carbon in lithium ion batteries.[1] However, silicon suffers from poor passivating behavior in organic electrolytes electrolyte side reactions, which both result in large irreversible capacity loss and gradual electrolyte consumption with a lithium inventory shift in the Li-ion cell. Furthermore, large crystallographic volume changes (~320%) occur during cycling, which leads to particle decrepitation, particle isolation, and electrode delamination. This has negative impact on the interfacial stability and the composite electrode mechanical integrity.
To assure electronic connectivity and mechanical integrity of the composite Si/C electrode during extended charge-discharge cycles, the polymer binder needs to exhibit unique physic-chemical properties. Therefore it is essential to understand the basic properties and the polymer binder and its effect on the electrochemical performance of Si/C anodes.
Chemical changes in polymer binders during cycling are carefully monitored and evaluated. Thin films (20 nm) of binder polymers like, polyacrylic acid lithium salt (PAALi), poly-1,1-difluroethane (PVdF) and poly(1-pyrenemethyl methacrylate) (PPY), are spin coated onto B-doped Si (100) wafers, which reproduce the thickness of the polymer films in the composite Si electrode if the polymer coats the Si particles uniformly. Electrochemical studies provide information about Li+ doping, possible polymer reduction, interfacial reactions and surface layer formation. The surface chemistry at the electrolyte side as well as the substrate/binder interphase is carefully analyzed and evaluated. These basic phenomena are then linked with the Si/C electrode electrochemical performance and electrode/cell life.
This study also focuses on the determination of the mechanical properties of various binders before and with cycling. Stress-strain curves, indentation measurements and adhesion tests give information about properties needed to withstand the large volume changes during cycling. Furthermore, possible chemical deterioration of binders and possible its adverse effects on adhesion, crack initiation, growth, and particle delamination are monitored. These results can be used to develop and/or select effective binder candidates, which can lead to more efficient Si-based high-energy Li-ion battery systems.

Acknowledgements

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, under the Applied Battery Research for Transportation (ABR) Program and Award Number DE-EE0006443.
[1] T. D. Hatchard, J. R. Dahn, Journal of the Electrochemical Society 2004, 151, A838.
Polyanion Glass Cathodes -- a Clearer Picture
Authors: Kercher Andrew Keith , Kolopus James A. , Sacci Robert L , Ruther Rose Emily , Carroll Kyler J. , Boatner Lynn A. , Dudney Nancy J 
Published: February 2020

Polyanion glasses are a relatively unexplored class of high capacity cathode materials (250-500 mAh/g) for applications in lithium ion batteries that can undergo intercalation and/or conversion electrochemical reactions. Unlike most crystalline polyanionic materials, polyanion glass materials can be varied widely in both the cation and polyanion composition. This huge compositional space presents an opportunity and a challenge: how do you tailor the glass composition to obtain optimal electrochemical performance?
Glass composition is often discussed in terms of: glass formers, stabilizers, and fluxes. In our polyanion glass cathodes, glass formers (borate, phosphate, vanadate, and molybdate) provided the overall amorphous network of the glass and can be tailored to improve the conductivity and ionic transport. Our “stabilizers” typically contained the electrochemically active cation (iron, copper, cobalt, nickel, silver, antimony). Fluxes typically are associated with alkali ions and tend to reduce the chemical stability of the glass, and interestingly, flux cations include the lithium ions that diffuse into and out of the glass during cycling. Compositional substitution in the glass former, stabilizer, and flux of a polyanion glass cathode were shown to affect the 1st cycle reversibility, long-term cycleability, and energy efficiency.
Characterization was performed on as-produced glass, glass cathodes at different states of charge, and glass cathodes at different amounts of cycling to understand the fundamentals of the glass cathode structure and its associated electrochemical performance. X-ray absorption spectroscopy performed on glass cathodes at different states of charge showed valence changes in both the stabilizer cation and a glass former (vanadate) during electrochemical reactions. The valence change in the vanadate was identified as the primary source of 1st cycle irreversible loss, whereas the valence changes in the stabilizer cation were typically reversible and were associated with gradual capacity fade during cycling. Transmission electron microscopy showed that metal nanoparticles formed uniformly throughout glass particles during the glass-state conversion reaction. IR & Raman spectroscopies of mixed polyanion glasses were used to identify key functional groups that were associated with reduced 1st cycle irreversible loss and improved energy efficiency during cycling.

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, under the Advanced Battery Materials Research (BMR) Program.
(Invited) Electron Channeling Contrast Imaging: Potential for Future Metrology in Semiconductor Industry
Authors: Vystavel Tomas , Prokhodtseva Anna , Schulze Andreas , Caymax Matty 
Published: February 2020

For future scaling of CMOS technology beyond the 10 nm node it is necessary to integrate high mobility semiconductors including (Si)Ge and III/V compounds on silicon substrates. The lattice mismatch between these materials and the Silicon platform can lead to the formation of defects which will cause a degradation of the final device performance. Therefore, a metrology technique is needed to monitor the presence and density of defects in blanket layer as well as in patterned structures such as fins. There are several techniques for defect metrology including optical methods, X-ray diffraction or transmission electron microscopy, however, expected defect densities (<105 cm-2) make them ineffective for this task.
Electron channeling contrast imaging (ECCI) is scanning electron microscopy (SEM) technique used for the visualization and characterization of crystalline defects including dislocations or stacking faults. Distortions of the crystal lattice of a material due to the presence of such defects cause the variation of the backscattered electron intensity allowing for the visualization of the defects. Application of ECCI proved to be a consistent method for assessing the density and Burgers vector of different defect types in various materials with reliability comparable to that of transmission electron microscopy (TEM). Moreover, TEM limitations related to the destructive sample preparation necessity, limited viewed area accessible for each sample and possible difference in the behavior of thin samples compared to bulk ones brings SEM based ECCI as excellent candidate for non-destructive investigation of large sample areas with low defect densities. For such an analysis, areas exceeding 105 μm2 in size need to be examined to ensure proper statistics. Therefore, automated acquisition of a set of tiles that can be stitched into a single image with a resolution allowing for the detection of single threading dislocations is required. Important parameter for high contrast ECCI of crystalline defects is the sample orientation with respect to the electron beam. The sample should be oriented close to the Bragg condition. This is facilitated by the acquisition of Electron Channeling Patterns and simultaneous sample tilting and/or rotation. For the majority of samples based on silicon wafers only require a couple of degrees tilt from the zone axis. Hence, the technique can be applied to 300 mm wafers easily.
The presented technique allows the visualizing and analyzing the density and distribution of threading dislocations in blanket SiGe layers of different defect densities, strain relaxed buffers as well as on (Si)Ge and III/V fin structures. Therefore we are able to demonstrate that automated image acquisition of ECCI has big potential as possible metrology tool for future semiconductor devices process.
Micro-Raman Characterization of Cluster Carbon Implanted Si before and after Rapid Thermal Annealing
Authors: Yoo Woo Sik , Kang Kitaek , Nishigaki Hiroshi , Hasuike Noriyuki , Harima Hiroshi , Yoshimoto Masahiro , Sekar Karuppanan 
Published: February 2020

To meet various physical property requirements of materials for advanced high performance devices, combinations of Si1-xGex and Si:C have been introduced for strain control in PMOS and NMOS regions of devices. Two types of carbon (C) doping techniques have been explored for tensile stress generation in the NMOS device region. Carbon-doped Si epitaxial growth with C doping and C-implantation into Si are two major approaches. Carbon implanted Si requires annealing for recrystallization, damage recovery and tensile strain control.
Strain characterization, monitoring and control are as important as material preparation. Non-contact, non-destructive strain and crystallinity characterization techniques with high spatial resolution and virtual depth profiling capability are strongly desired for in-line monitoring.
In this study, we report the micro-Raman characterization results on cluster C-implanted Si for tensile strain generation before and after various rapid thermal annealing (RTA) techniques and conditions. Phosphorous ion clusters (P4) (8 keV, 4x1015 cm-2) were implanted with carbon ion clusters (C7) targeting 1.3% and 1.5% flat C profile (~50 nm from the surface). Various excitation wavelength laser beams were used in Raman characterization for virtual strain depth profiling. Flash anneal (fRTP) at 1200oC and impulse spike anneal (iRTP) at 1000oC and 1050oC were used as annealing conditions. As-implanted Si wafers showed almost no Raman signal due to the crystalline lattice damage from high dose cluster ion beam implantation. After RTA of implanted Si wafers under different techniques and conditions, significant broadening and shift of Raman peaks towards the lower wavenumber side was measured, indicating the presence of tensile strain and crystallinity alterations. X-ray diffraction (XRD), secondary ion mass spectroscopy (SIMS) depth profiling and transmission electron microscopy (TEM) analysis results will be reported along with multiwavelength micro-Raman characterization results.
Figure 1 shows 363.8nm excited micro-Raman spectra from reference Si and cluster C implanted Si wafers before and after rapid thermal annealing (RTA).

Figure 1
High Thermal Stability of Tensile Strained Direct Gap GeSn Crystallized on Amorphous Layers
Authors: Li Haofeng , Cuervo Covian Alejandra , Wang Xiaoxin , Liu Jifeng 
Published: February 2020

In this paper, we systematically research the thermal evolution of substitutional Sn composition, tensile strain, and the direct bandgap of highly (111) textured, direct-gap Ge1-xSnx (0.075<x<0.085) thin films crystallized on amorphous SiO2 layers. We are able to demonstrate highly effective strain induced band-engineering in Ge1-xSnx as high performance optoelectronic materials for monolithic 3D electronic-photonic integration. For a Ge0.913Sn0.087 thin film, xSn stays at 8.7 at. % without any Sn segregation even after 2 hours of annealing at the crystallization temperature of 464 oC, indicating that the material is thermally stable in the entire back-end-of-the-line processing temperature range (<450 oC). We then sequentially anneal the Ge0.913Sn0.087 sample from 500 oC to 700 oC at a step of 50 oC, for 15 min each step, and selectively etch away any surface segregated Sn after each step. After analyzing the materials using a combination of X-ray Diffraction (XRD) and Raman spectroscopy, we determine that the crystallinity improves with the increase of annealing temperature, as evidenced by decreased full width at half maximum of both Raman and XRD peaks. The GeSn film maintained its strong (111) texture, as evidenced by the >270 ratio of the strongest to second strongest XRD peak. The xSn only decreases slightly from 8.3 at. % at 500 oC to 7.4 at. % at 700 oC, still ~7 times higher than the equilibrium solubility limit of ~1 at. % whereas the in-plane tensile strain e|| increases by nearly 4 times from 0.12% to 0.44%. By measuring and fitting the absorption spectra, we find that remarkably, the 0.44% thermally induced biaxial tensile strain reduces the direct bandgap by as much as 0.125 eV, twice as effective as the tensile strain in Ge(100) films. Due to a smaller Poisson’s ratio under biaxial tensile stress, the (111) oriented films experience larger volume dilatation than their (100) oriented counterparts under the same in-plane tensile strain, thereby enhancing the beneficial effects of tensile strain on the indirect-to-direct gap transition. By fitting the data with deformation potential theory, we derive a dilatational deformation potential of -12.8+/-0.8 eV for Ge1-xSnx thin films with xSn=8 at.%. Despite of the slight decrease in Sn composition at high annealing temperatures, the tensile-strain-induced direct-gap shrinkage, not only extends the optical response to λ = 2.8 um for MIR applications but also leads to stronger direct-gap semiconductor behavior. These results indicate that tensile strained GeSn crystallized on amorphous layers offers both excellent direct-gap optoelectronic properties and fabrication/operation robustness for integrated photonics. The same concept can also be readily applied to epitaxial GeSn on (111) substrates to achieve more effective strain-induced band engineering.

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High Performance OTFTs with CNT/Metal Hybrid Electrodes and Their Application to Amoled Panel
Authors: Song Chung Kun , Kim Jae Sun 
Published: February 2020

The contact resistance is an important factor to significantly affect performance of organic thin film transistors (OTFTs). In this paper, a new carbon nanotube (CNT) based hybrid electrodes are introduced for a low contact resistance of source and drain electrodes of OTFTs. The hybrid electrodes consist of the solution-processed CNTs and a metal (Al; CNT/Al or Au; CNT/Au) evaporated on the CNTs. The contact resistance of CNT/Al and CNT/Au hybrid electrodes was varied depending upon the thickness of Al and Au, as shown in Fig.1. For CNT/Al hybrid electrodes, the contact resistance exhibited the minimum of 2.9 KW∙cm (VGS = -30 V) at the Al thickness of 5 nm, which was smaller than 13 KW∙cm of the bare CNT electrodes and tremendously smaller than 4 MW∙cm of Au electrode. It was noticeable that the minimum contact resistance of CNT/Au was 0.9 KW∙cm at the Au thickness of 5 nm which was the lowest value ever reported. The mobility of OTFTs, which used pentacene as the semiconductor and polyvinylphenol as the gate dielectric, also followed the same metal thickness dependence as the contact resistance. The maximum mobility of OTFTs using CNT/Al and CNT/Au electrodes was 0.78 cm2/V∙sec and 1.0 cm2/V∙sec, respectively, at the same thickness of 5 nm, which was larger than 0.3 cm2/V∙sec of the bare CNT electrodes. A major origin of such enhancements was identified to be the smallest energy difference, which was obtained at the metal thickness of 5 nm, between the work function of the CNT/metal hybrid electrodes and pentacene HOMO (5.1 eV).
The CNT/Au electrodes were applied to OTFTs in AMOLED panel. The AMOLED panel consisted of 64 x 64 pixels where each pixel was composed of 2 OTFTs (switching and driving OTFT), 1 capacitor, and 1 OLED. A shown in Fig.2, the AMOLED panel successfully worked to display some patterns.

Figure 1