bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Molecular Engineering on Transition Metal Dichalcogenides
Authors: Kiriya Daisuke 
Published: February 2020

Molecular interaction and assembly is an essential process in various fields such as in chemistry, biology and materials science. As one of sophisticated systems, the process is successfully incorporated in biology to construct functional structures, including the membrane of cells. Through the interactions of each molecule, molecules show assembly to form functional patterns and structures. We are trying to extend the molecular interaction/assembly onto inorganic electronic materials/devices. This presentation shows our recent results of molecular interaction on 2D materials, especially the semiconducting 2D material, transition metal dichalcogenides (TMDCs).1,2,3

The TMDC is constructed from atomically thin layers (thickness ~0.7 nm) with van der Waals interaction, and is expected to make tiny optoelectronic devices due to their thin nature. However, the essential requirement for controlling carriers is a problem because the conventional methods, such as ion plantation, are not applicable due to its atomically thin nature. We found that mere contact of a dopant molecule with MoS2, the donor molecule is effective to control the carrier concentration of a TMDC, MoS2.1 They formed an organic-inorganic electron transfer interaction (Fig. 1a). As a result, the doping level of MoS2 can be varied depending on the amount of the donor molecule. We also found that the doping process can make a high-performance MoS2 transistor with subthreshold swings as low as 77 mV/dec. close to the theoretical limit.
We further examined the assembly and pattern formation of molecules on MoS2; MoS2 was used as a new class of substrates for assembling or patterning molecules (Fig. 1b). 2 First, we found that MoS2 is a model substrate for growth of in-plane Au nanowires (NWs). Au NWs show oriented growth despite the nearly 8% lattice mismatch between MoS2 and Au. Au NWs on the MoS2 surface are oriented along three symmetrically equivalent directions within the substrate that arise from the symmetry of MoS2 that templates the oriented growth. In terms of the electronic state point of view, the growth process of Au NWs includes a strong charge transfer process between Au NWs and MoS2, resulting in degenerate p-doping of MoS2.
We also found that a dopant molecule showed a pattern formation on MoS2 as like cellular structure or patterns shown in natural systems. We destabilized an ultrathin molecular film on MoS2 by external perturbation, induced lateral diffusion of molecules on MoS2 surface and showed various patterns such as tiny holes, networks, maze structures. Since the lateral undulation of the pattern was on the 100 nm scales, the pattern was revealed to modify MoS2 characteristics. In the presentation, the details of the above research will be discussed from the structural point of view to the electronic point of view.

References:

1D. Kiriya et al., J. Am. Chem. Soc. 2014, 136, 7853. 2
Adv. Funct. Mater. 2015, 25, 6257. 3M. Amani*, D.H. Lien*, D. Kiriya*
et al., Science, 2015, 350, 1065.

Figure 1
Evaluation of Model for Determining Nitrogen Doping Concentration from Resultant Strain in Heavily Doped 4H-SiC Crystals
Authors: Ailihumaer Tuerxun , Yang Yu , Guo Jianqiu , Raghothamachar Balaji , Dudley Michael 
Published: February 2020

Lattice strain in 4H-SiC substrate wafers can strongly affect the performance of power electronic devices especially under the high temperature operation. The impurity incorporation in highly doped 4H-SiC crystals can result in significant lattice parameter change. Recently we reported [1] the synchrotron X-ray topographic contour mapping [2] technique to deconvolute lattice parameter variations from lattice tilt and thus generate strain maps. These strain maps have been incorporated into an anisotropic elasticity model to derive the nitrogen doping concentration variation in the 4H-SiC wafer. Doping distribution can be derived using a set of anisotropic strain maps detected by recording series of diffraction contours across the same region. The nondestructive contour mapping method we developed is capable of not only determining the concentration but also the distribution of the doping i.e. a doping map. In order to verify the doping level determined by contour mapping, we prepared samples with different N-doping levels. Contacts were created by depositing Ni using e-beam evaporator followed by rapid annealing. Hall effect measurements have been carried out on these samples to measure the carrier concentration in order to determine the doping values. The measured values are found to be in good agreement with the doping map derived using our contour mapping method.
Reference

Yu Yang, Jianqiu Guo, Balaji Raghothamachar, Xiaojun Chan, Taejin Kim, Michael Dudley, J. Electron. Mater. 47(2), 938-943 (2018).

J. Guo, Y. Yang, B. Raghothamachar, M. Dudley, and S. Stoupin, J. Electron. Mater. 47(2), 903-909 (2018).
Electrolysis Pumping on Centrifugal Microfluidic Platforms for Automation of Bioanalytical Assays
Authors: Romero Soto Fabian Oswaldo , Aeinehvand MohammadMahdi , Jimenez Moreno Martin Francisco , Mager Dario , Madou Marc J , Martínez-Chapa Sergio Omar 
Published: February 2020

One of the advantages of Lab on a Disc (LoD), compared to Lab on a Chip (LoC), is the use of centrifugal forces to move liquids within the chambers and microchannels; eliminating the need of external mechanical pumps (e.g., syringe pump) and piping networks for the automatization of bioanalytical assays. However, the centrifugal force is unidirectional and therefore liquids can only be displaced from the center to the edge of the disc. This prevents the possibility of utilizing all the available space in the disc for the implementation of a complex microfluidic process. To overcome this limitation, we developed an electrolysis system to induce a pneumatic force to move liquids towards the center of a spinning disc or against the direction of centrifugal force. We developed a microfluidic disc that contains a series of electrolysis pumps and peptide microarrays to automate a multiplexed immunoassay for the detection of different antibodies e.g., Ha and anti-flag antibodies. The pumps on this centrifugal microfluidic platform are powered and controlled wirelessly using the electronics-LoD [1]. In general, the develop pumping system allows for the best use of the limited space of microfluidic disc and the automation of complex bioanalytical process for point of care applications.
[1] S.M.T. Delgado, D.J. Kinahan, F.S. Sandoval, L.A.N. Julius, N.A. Kilcawley, J. Ducrée, D. Mager, Fully automated chemiluminescence detection using an electrified-Lab-on-a-Disc (eLoaD) platform, Lab Chip. 16 (2016) 4002–4011. doi:10.1039/C6LC00973E.
Disordered Rocksalt Type Li-Rich Manganese Oxyfluoride As High-Capacity Cathode Material for Rechargeable Lithium Ion Batteries
Authors: Natsui Ryuichi , Ikeuchi Issei , Ohuchi Satoru , Nakura Kensuke 
Published: February 2020

For the coming full-fledged xEV era, rechargeable lithium ion batteries with higher capacities are strongly desired. However, the current commercial cathode materials, such as layered-rocksalt oxide, are reaching the limit of their theoretical capacities.
Li-rich oxide cathode materials, which can access not only to transition metal redox reactions but also to redox reactions during the Li insertion/de-insertion, are expected as candidates for the next generation high capacity cathode materials as they can store much more Li ions than the current commercial cathode materials. However, one of the main drawback of these materials are voltage-fading with structural transition upon electrochemical cycling. It is considered due to oxygen loss at surface and transition metal rearrangement [1][2].
To suppress the oxygen loss without decreasing capacity, we focused on the oxyfluoride cathode material. Especially, we confirmed that disordered Rocksalt type-Li2MnO2F synthesized by mechanochemical process exhibit a discharge capacity of 330mAh/g with both transition metal and oxygen redox reaction, which is much higher than conventional cathode materials (200mAh/g) [3]. Recently, Bruce et al, disclosed that the Li1.9Mn0.95O2.05F0.95 does not exhibit oxygen loss from the lattice. This indicates that the Li-rich oxyfluoride is one of the noteworthy material for the high capacity cathode materials.
In this study, we will discuss the possibility of the oxyfluoride materials for the next-generation high capacity cathode material from the view point of structures and compositions by comparing with some other oxide cathode materials without fluorine doping.
[1] N. Yabuuchi et al, J. Am. Chem. Soc. 133 (2011) 4404
[2] Y. S. Meng et al, Energy Environ. Sci., 4 (2011) 2223
[3] R. Natsui, K Nakura, POSITIVE ELECTRODE ACTIVE MATERIAL AND BATTERY, WO2017/013848
[4] P. G. Bruce et al, Energy Environ. Sci., (2018) Advanced Article
Advanced Impedance Analysis of Calendar and Cycle Aged NCA-LCO/Graphite Lithium-Ion Batteries
Authors: Dippon Michael , Weiss Michael , Gantenbein Sophia , Ivers-Tiffée Ellen 
Published: February 2020

Lithium-ion batteries deteriorate in energy and power density over lifetime. Power density fades away with increasing internal resistance (Ri) and is generally monitored by pulse measurements, which do not describe details of the underlying loss contributions.
Loss contributions as (i) ohmic resistance R0, (ii) contact resistance RCC and (iii) charge transfer resistance RCT are separated by electrochemical impedance spectroscopy (EIS) combined with the distribution of relaxation times method (DRT), and quantified using a simple equivalent-circuit model (Figure 1). This approach allows the systematic investigation of Li-ion batteries over lifetime, and gives more insight into the effect of temperature, cycling profiles and discharge/charge rates.
We present a lifetime analysis of a high-energy pouch cell (KOKAM 560 mAh), using a wide set of procedures during cycling and calendar aging. The investigated cell consists of a NCA-LCO blend cathode and a graphite anode. The relationship between numerous test profiles (variation of temperature, charge/discharge rate and depth of discharge) and predominant aging mechanism of the cell resistance is quantified versus begin of life (BOL) and its origin is discussed in great detail.

Figure 1
(Invited) Screening Plus Testing of Cathode Materials for Ca and Mg Batteries
Authors: Arroyo-de Dompablo M. Elena , Torres Arturo , Padilla M. Pilar , Luque Javier , Bardé Fanny , Tchitchekova Deyana , Black Ashley , Ponrouch Alexandre , Palacin M Rosa 
Published: February 2020

While the current state-of-the-art in rechargeable batteries is the Li-ion technology, research efforts are intensified towards the development of alternative technologies to satisfy the ever-increasing demand for enhanced energy density. The development of rechargeable batteries based on the intercalation reaction of multivalent cations (Ca2+, Mg2+, Al3+) is a current challenge for electrochemical energy storage. Designing such batteries demands the identification of competitive electrode materials and electrolytes for each particular active ion. In the last years, we have combined computational and experimental techniques in the search of potential cathode materials that could reversibly insert Mg/Ca ions [1-4].
First principles calculations are used to predict three fundamental electrochemical properties of materials: average intercalation voltage, specific capacity and ionic mobility. Benchmarking the computational results with experimental evidences is a necessary step to accelerate reliable materials design based on DFT calculations. Therefore, our experimental investigations comprise the synthesis, characterization and electrochemical testing of materials. In this work, we confront computational and experimental results for selected oxides, nitrides, sulphides and silicate materials. We will show that the combined computational/experimental approaches lead to proof of concept and rationalization for the reversible electrochemical intercalation and deintercalation of calcium in TiS2 [4].
Acknowledgments: Authors are grateful for financial support from Ministerio de Ciencia e Innovación (grant MAT2014-53500-R), the European Union H2020-FETOPEN funded project CARBAT-766617 and Toyota Motor Europe.
References:
[1]. M.E. Arroyo-de Dompablo, C. Krich, J. Nava-Avendaño, M.R. Palacin, F. Barde. Phys. Chem. Chem. Phys. 18 (2016) 19966.
[2]. M.E. Arroyo-de Dompablo, C. Krich, J. Nava-Avendaño, N. Biskup, M.R. Palacin, F. Barde. Chem. Mater. 28 (2016) 6886.
[3] R. Verrelli, M.E. Arroyo-de Dompablo, D. Tchitchekova, A.P. Black, C. Frontera, A. Fuertes, M.R. Palacin. Phys. Chem. Chem. Phys., 19 (2017) 26435
[4]. D. Tchitchekova, A. Ponrouch, R. Verrelli, T. Broux, C. Frontera, A. Sorrentino, F. Barde, N. Biskup, M.E. Arroyo-de Dompablo, M.R. Palacin. Chem. Mater. 30 (2018) 847
LiNi0.6Mn0.2Co0.2O2 Dry-Coated with Nano- Alumina As Positive Electrode Material
Authors: Zheng Lituo , Obrovac M. N. 
Published: February 2020

Applications of lithium ion batteries in grid storage and electric vehicle require long lifetime. Surface coating of active material is an effective way to improve the long-term cycling of lithium ion batteries.1 Most of the coating methods reported so far are wet-coating method, which produces waste liquid and requires additional drying process. In this study, LiNi0.6Mn0.2Co0.2O2 was coated with nano-alumina using a convenient dry-coating method and characterized in Li cells.
Commercial LiNi0.6Mn0.2Co0.2O2 powders (obtained from Umicore) were mixed with 3% Al2O3 (13 nm, from Sigma-Aldrich) using a dry-coating method. For comparison, LiNi0.6Mn0.2Co0.2O2 powders were also mixed with 3% Al2O3 by hand-grinding. Electrodes were made with active material, PVDF binder, carbon black at a ratio of 86:7:7 and dried under vacuum at 120 ℃ overnight. 1M LiPF6 in a solution of EC and DEC (volume ratio 1:2) was used as electrolyte and Li foil was used as counter/reference electrode.
Figure 1(a) shows the SEM image of LiNi0.6Mn0.2Co0.2O2 powders. Secondary particles with spherical morphology were observed. The average particle size is ~1 μm for primary particle and ~10 μm for secondary particle. Figure 1(b) shows the SEM image of LiNi0.6Mn0.2Co0.2O2 powders coated with 3% Al2O3 using the dry coating method. Figure 1(c) shows the SEM image of LiNi0.6Mn0.2Co0.2O2 powders mixed with 3% Al2O3 by hand-grinding. The dry coating method produced a more homogeneous and dense coating, compared to materials produced by hand-grinding.
Figure 2 shows the cycling performance at C/2 for all the materials cycled between 3 V – 4.4 V. Compared to pristine NMC 622, the materials processed with 3% Al2O3 displayed lower reversible capacity. However, the cycling performance was improved for both materials. Notably, materials dry-coated with 3% Al2O3 showed little capacity fade in 50 cycles. This study gives an example of using dry coating method for improving the cycling performance of positive electrode materials for lithium ion batteries.
References

Z. Chen et al., J. Mater. Chem.,
20, 7606-7612 (2010)

Figure 1
Stress and Electrochemical Analyses of LiNixMnyCo1-x-YO2(NMC)/Graphite Lithium-Ion Battery with Real 3D Microstructures
Authors: Kim Sangwook , Huang Hsiao-Ying Shadow 
Published: February 2020

LiNixMnyCo1-x-yO2 (NMC) is one of promising cathode materials in lithium-ion batteries (LIBs) for power tools and electric vehicles due to their higher specific capacity and energy density. However, it is observed that repeated cycling leads to micro-scale fracture along the grain boundaries in the secondary particles of NMC, and it could eventually cause low cycling stability and irreversible capacity retention.
The aim of this study is to investigate the correlation of mechanical stresses and electrochemical battery degradation. Specifically, mechanical stress and strain caused by lithium intercalation and diffusion in both cathode and anode were calculated and crack initiation in particles was predicted. Furthermore, a modified Butler-Volmer equation, which accounts for the influence of mechanical stress on electrochemical reactions, is considered. In this study, we adopted real 3D microstructures of both anode (graphite) and cathode (NMC) based on over 100 images from a synchrotron radiation X-ray tomographic microscopy (SRXTM). The 3D finite element model (FEM) was developed by COMOSL Multiphysics 5.2a and followed by coupled electrochemical and mechanical analyses of a whole cell, including cathode, anode, and electrolyte.
As the first step, the electrochemical model based on the microstructure was compared with results from the previous study with a simple geometry (e.g. spherical particles). Specifically, the real 3D microstructure model, concentration, polarization, over potential, and von-Mises stress distribution across both electrodes (e.g. graphite and NMC) were computed under different C-rates. We observed that effects of phase transformation of NMC on mechanical stress was significant during discharging processes. Moreover, the model revealed that at particle connections where exhibit complicated geometries and the bulged regimes of smaller curvature showed higher stress and were vulnerable to particle cracking. Finally, it is confirmed that mechanical stress plays important role in electrochemical performance.
This computational model can make a solid foundation to understand the relationship between mechanical stress and electrochemical performance in NMC/graphite battery chemistry. It might be helpful to understand key factors in the deterioration of Lithium-ion batteries with higher C-rates and longer cycle life.
Study of the Influence of Carbon Additive Content in LiMn0.5Ni1.5O2 Cathodes in Lithium Ion Batteries
Authors: Guzmán Gregorio , Diaz-Chavez L , Ramos-Sánchez Guadalupe , González I 
Published: February 2020

LiMn0.5Ni1.5O2 is one of the most important materials for high voltage Lithium Ion batteries. Due to the high operation voltage, the LiMn0.5Ni1.5O2 – electrolyte interphase suffers high reactivity which limits the cyclability of the electrodes. Several modifications to the electrolyte, cathode material, and inclusion of additives in both phases have been investigated, however although they have provided slight improvements, the reasons behind the stability enhancement still are not fully understood [1]. Additionally, the presence of carbon additives has also been reported to influence the initial capacity and cyclability of the cathodes; however, the great variety of cathode composite compositions, type of carbon additives and experimental conditions makes difficult a fair comparison between them. In this work the influence of carbon additives at two compositions (2 and 10%) is studied by cyclic voltammetry charge and discharge curves and Electrochemical Impedance spectroscopy (EIS), the cyclability in both cases resulted very high with high coulombic efficiency close to 100% with Li anodes. The EIS spectra were adjusted to several equivalent electric circuits, while most of them results in a fair agreement, the explications derived from them are not applicable to all cases, moreover, a phenomenological interpretation was proposing which resulted in excellent xi2 adjustment (10-5) which overpasses by far state of the art results (10-3) with limited phenomenological information. In this work the EIS was applied at several conditions of the electrode and in general it was observed an enormous increase of charge transfer resistance as cycling goes on. However, the lower carbon content results in an even faster degradation process which is also accelerated by longer times at higher voltages. Therefore, the carbon additive also has a big influence on the reactivity of the electrode-electrolyte interphase and can serve as additional tool to increase the cyclability of the electrodes.

Acknowledgements This work was supported, GR thanks (project seciti/080/2017) IG thanks CONACYT (proyect 237343) for financial support. G. Guzman is grateful to CONACYT for the scholarship granted to pursue his doctoral studies.
[1] Kang-Joon Park,a Byung-Beom Lim,a Moon-Ho Choi,a Hun-Gi Jung, Yang-Kook Sun, Marta Haro, Nuria Vicente, Juan Bisquert and Germá Garcia-Belmonte, J. Mater. Chem. A, 2015, 3, 22183
Strategic Architecture of Silicon Nanolayer-Embedded Graphite Hybrid for High Energy Lithium-Ion Battery Anodes
Authors: Ko Minseong , Oh Pilgun , Jung Jae-il 
Published: February 2020

As the widespread emergence of modern technologies combined with human life, lithium ion battery (LIBs) has become one of the most important power supplier for mobile electronic devices, electric vehicles and stationary applications. However, the current LIBs provide a low energy density with approaching to the capacity limits, which emphasize the urgent need for high energy density battery systems.
Herein, we have prepared the amorphous silicon nanolayer-embedded graphite/carbon (SGC) hybrids by chemical vapor deposition (CVD) method with developing the cost-effective and scalable pyrolysis system. With developing an industrial-relevant modified CVD process, sophisticated structure of optimum SGC hybrids achieved high reversible capacity (523 mAh g-1) and unprecedented coloumbic efficiency (92%) at a 1st cycle in the industrial standard electrode density (> 1.6 g cc-1) and areal capacity loading of > 3.3 mAh cm-2. Moreover, fabricated SGC electrode confirmed rapid increase of cycling efficiency upward of 99.5% over only 6th cycles and exactly allowed favorable cyclability of 96% capacity retention after 100 cycles and high rate capability comparable to the industrial graphite anode. In addition, the electrode composed of SGC hybrids entirely overcame the detrimental effects of the volume variation problems, exhibiting 23% of additional expansion excepting for graphite counterpart. This, in turn, completely preserved the electrical interconnectivity and mechanical integrity without any cracks and contact losses. Finally, a prototype full cell device is demonstrated with high voltage lithium cobalt oxide (LCO) cathode through the coin cell configuration, which achieved 92% of capacity retention after 100 cycles with considerable potential toward next generation target as practical devices. Consequently, this successful SGC hybrid anodes could be proposed for commercial extension to the next generation high-energy battery systems as a major breakthrough for electric vehicle or grid energy storage applications.

Scheme 1. Schematic of fabrication process for SGC hybrids. Gas phase of Silane (SiH4) can easily adsorb and penetrate on a pristine graphite (PG), which leads to homogeneous and highly pure amorphous silicon nanolayer coating on both inner and outer surface of PG as silicon graphite (SG) hybrids. In the end, SGC hybrids are invented from SG through carbon coating with acetylene (C2H2) gas by CVD method.

Figure 1