bluuebunny/crossref_metadata_2025_split huggingface dataset:
Layered Li-rich Oxide Cathode Microparticle 0.4Li2MnO3∙0.6Li(Mn0.43Ni0.36Co0.21)O2 Decorated with Nano Grains and its Electroochemical Performance
Authors: Wang Sungeun , Jung Dae Soo 
Published: February 2020

The development of alternative energy sources has become the primary strategy to overcome unstable crude-oil prices and the issues associated with climate change. Seasonal variations in alternative energy sources have prompted the need for an energy storage system. Reduction of carbon dioxide is also a key strategy for solving the problem of climate change. Carbon dioxide produced by transportation constitutes almost one-third of total carbon dioxide production. Replacing gasoline-based transportation with electric vehicles represents a promising solution to reduce carbon dioxide emissions.
Among the various types of batteries, lithium secondary batteries are considered the most attractive option because of their light weight and high power density. However, the current technical specifications are not quite satisfactory for full scale commercialization of electric vehicles (EVs) and hybrid electric vehicles (HEVs). Increasing driving range and reducing the cost of batteries remain key issues that need to be addressed.
Nano-composite layered compounds of xLi2MnO3·(1-x) LiMO2 (M = Ni, Co, Mn) were recently shown to exhibit high capacities in the high voltage region of –4.6 V and have lower cost and better safety compared to LiCoO2, which is used in commercial lithium-ion batteries. However, the layered xLi2MnO3·(1-x) LiMO2 shows low rate capability due to low electronic conductivity, which is caused by the insulating Li[Li1/3Mn2/3]O2 component. Therefore, the low rate capability of these batteries needs to be addressed for use in EVs and HEVs, which require fast charge/discharge reactions.
Various methods have been developed to improve the rate capability of layered xLi2MnO3·(1-x) LiMO2 composite particles, such as doping with another transition metal, surface modification, and coating. However, attempts to control the morphology and particles size has not been reported due to limitations in the preparation methods. The cathode particles are normally prepared by a solid-state reaction or liquid phase methods and these methods require a high calcination temperature and long calcination time to obtain desirable composite phase. These calcination conditions result in aggregation and growth of primary particles, which degrades the diffusion of lithium ions between the electrode and electrolyte.
Spray pyrolysis has recently been used for the preparation of multicomponent ceramic particles due to its several advantages, such as being a simple system, ease of controlling particle size and preparing spherical particles of multi-components and formation of a pure well-crystallized phase at low calcination temperature. Thus, in this study, we prepared spherical 0.4Li2MnO3∙0.6Li(Mn0.43Ni0.36Co0.21)O2 microparticles decorated with nano-grains via spray pyolysis and the structural and electrochemical performance of the prepared particles were investigated.
Fluorinated Solvent Based Electrolytes for Lithium-Sulfur Batteries
Authors: Bouchal Roza , Boulaoued Athmane , Johansson Patrik 
Published: February 2020

The lithium-sulfur battery is a promising next generation battery (NGB) technology, but with a common major complication of irreversible loss of active material (S) from the composite cathode (C/S). Elemental sulfur and polysulfides (Li2Sx, 4 ≤ x ≤ 8, PS) generated during the charge/discharge process are both dissolved into the electrolyte and the PS shuttle between the anode and the cathode without performing useful work. This shuttling results in low Coulombic efficiency, low cycling capacity, and increased internal cell resistance.1, 2

One way to reduce the PS shuttling is to employ electrolytes that only sparsely dissolve sulfur and PS.3, 4 Here we have employed several such electrolytes based on fluorinated carbonates and ethers and studied the resulting performance including the cycle life of the Li-S battery cells made. By combining physico-chemical characterization, electrochemical performance assessments, and operando confocal Raman spectroscopy we gain a better understanding of the PS formation. The overall outcome can be used to guide the selection of solvents for more performant Li-S batteries.
The research presented has received funding through the HELIS project (European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 666221).

References

1 Q. Pang, X. Liang, C. Y. Kwok and L. F. Nazar, Nat. Energy, 2016, 1, 1–11.
2 P. Bonnick, E. Nagai and J. Muldoon, J. Electrochem. Soc., 2018, 165, A6005–A6007.
3 S. Drvarič Talian, S. Jeschke, A. Vizintin, K. Pirnat, I. Arčon, G. Aquilanti, P. Johansson and R. Dominko, Chem. Mater., 2017, 29, 10037–10044.
4 S. Gu, R. Qian, J. Jin, Q. Wang, J. Guo, S. Zhang, S. Zhuo and Z. Wen, Phys. Chem. Chem. Phys., 2016, 18, 29293–29299.
Highly Enhanced Cycleability from High Crystalline Biaxially Aligned CNT Web for Li-Air Cathode Applications
Authors: Kim Hyunjin , Cho Youngshik , Byeon Minhu , Baek WoonJoong , Kwon Hyuk Jae , Lee Dong Joon , Lee Hyunpyo , Jung Yeonsu , Park Chong Rae , Im Dongmin 
Published: February 2020

In recent years, Li-O2 batteries have attracted a great deal of attention due to the high theoretical capacity for applications as electronic vehicles. Carbon nanotubes are widely used as cathode materials for Li-O2 batteries because of their high conductivity, high surface area and low density. However, due to their hydrophobic surface properties and the high van der Waals interaction between their walls, they tend to aggregate on their own, failing full use of the CNT surface. Therefore, it is necessary to engineer the nanoscale space between the CNTs such that each CNT aligns with each other and the nanoscale spacing lies between them. In this way, it is possible for the ionic liquid electrolyte and oxygen to access individual CNTs and enable uniform Li2O2 formation.
In this research, we developed a one-step process for biaxially oriented, highly crystalline CNT fabrics using a combination of floating catalyst chemical deposition (FCCVD) and one-step direct spinning technology. A highly crystalline DWCNT with a diameter of 6 nm was synthesized by FCCVD using ferrocene, thiophene, and methane, as precursors, and as-spun CNTs were woven into fabric by 2-directional spinning process. The intensity ratio between D and G bands (ID/IG) of 0.06 showed high crystallinity of CNT surface. The microscopic architectures of randomly oriented CNT fabric and biaxially oriented CNT fabric were investigated using a high-resolution scanning electron microscope (See Figure 1.(a) and (b)). The biaxial orientation was reconfirmed using a polarized Raman spectroscopy.
In order to investigate the effect of the microscopic structure on the performance of the Li-O2 battery, we have assembled Li-O2 cells using a random CNT fabric and a biaxially aligned CNT fabric as a cathode. In the random CNT cathode, the charging overpotential gradually increases, leading to rapid decay of capacity upon cycling (Fig. 1(c)). The increase in overpotential is typically associated with the accumulation of insulating byproducts due to parasitic reactions involving the electrolyte or the carbon electrode. However, in the biaxially aligned CNT electrode, a much improved cycle stability and small charging overpotentials are demonstrated (Fig. 1.(d)). This dramatically improved cycling performance might result from the increase in the surface area corresponding to mesopores, providing more effective sites capable of carrying discharge products such as Li2O2. In addition, Li-O2 cathode using biaxially aligned CNT fabric can offer open framework in which O2 and electrolytes can access to the individual CNTs, facilitating reversible Li2O2 formation and removal, and consequently exhibiting enhanced cyclability.

Figure 1
Hexacyanoferrate Cathode for Superior Na-Ion Batteries
Authors: Zhang Wuxing , Wan Min , Tang Yang , Liu Yang , Huang Yunhui 
Published: February 2020

Sodium iron hexacyanoferrate (Fe-HCF) is regarded as a potential cathode material for sodium-ion batteries (SIBs) due to its high specific capacity, low cost, facile synthesis and environmentally friendly. However, Fe-HCF always suffers from poor electronic conductivity, low crystallinity and side reactions with electrolyte, leading to poor rate performance, low coulombic efficiency and deterioration of cycling stability. Herein, we report the green and facile synthesis to encapsulate Fe-HCF microcubes with potassium nickel hexacyanoferrate (Ni-HCF) and PPy, separately, the surface modified Fe-HCF can exhibit excellent electrochemical performance as cathode in SIBs (Fig. 1).
Firstly, the Fe-HCF@PPy composite exhibits a discharge capacity of 113.0 mA h g-1 at a current density of 25 mA g-1 and 75 mA h g-1 at 3000 mA g-1. Greatly improved cycling stability is attained with 79% capacity retention over 500 cycles at 200 mA g-1. The superior rate capability and excellent cyclability can be ascribed to the effects from PPy as both electronic conductor to enhance the conductivity and protective layer to prevent the side reactions.
Secondly, the core-shell Fe-HCF@Ni-HCF composite delivers a reversible capacity of 79.7 mAh g-1 at 200 mA g-1 after 800 cycles and a high coulombic efficiency of 99.3 %. In addition, Fe-HCF@Ni-HCF exhibits excellent rate performance, retaining 60 mAh g-1 at 2000 mA g-1. The results show that Fe-HCF@Ni-HCF integrates the advantages of both Fe-HCF and Ni-HCF, making it electrochemically stable as cathode material for SIBs.

Figure 1
Glyme-Na Salt Equimolar Complex Electrolytes for Sodium Ion Batteries
Authors: Dokko Kaoru , Terada Shoshi , Susa Hiroko , Ueno Kazuhide , Watanabe Masayoshi 
Published: February 2020

Physicochemical and electrochemical properties of glyme-Na salt equimolar complex electrolytes were investigated. The pentaglyme (G5) forms complexes with Na salts in 1:1 molar ratio.1,2 The structures of complexes of G5-Na[TFSA] (TFSA: bis(trifluoromethanesulfonyl)amide) and G5-Na[FSA] (FSA: bis(fluorosulfonyl)amide were investigated using single crystal X-ray diffraction and ab initio calculations. In the crystals of G5-Na[TFSA] and G5-Na[FSA], G5 molecules wrap around Na+ ion and form [Na(G5)]+ complex cations. The melting points of [Na(G5)][TFSA] and [Na(G5)][FSA] are 32 °C and 41 °C, respectively.1 To apply the G5-Na salts complexes to sodium ion batteries as electrolytes at room temperature, the complexes were mixed with a low polar solvent, HFE (HFE: 1,1,2,2–tetrafluoroethyl 2,2,3,3–tetrafluoropropyl ether (CF2H−CF2−O−CH2−CF2−CF2H)). The liquid structures of [Na(G5)][TFSA]/HFE and [Na(G5)][FSA]/HFE were elucidated using Raman spectroscopy. The complex structure of [Na(G5)]+ complex cation were kept in the liquids, and the HFE hardly participate in the solvation of Na+ in the solutions.3 [Na(G5)][FSA]/HFE showed higher ionic conductivity than [Na(G5)][TFSA]/HFE owing to the higher mobility of FSA than that of TFSA.
The reversibility of the Na metal deposition/dissolution changed greatly depending on the electrolyte composition. The Coulombic efficiency of Na metal deposition-dissolution in [Na(G5)][FSA]/HFE reached to 95 % while the efficiency in [Na(G5)][TFSA]/HFE was much lower. X-ray photoelectron spectroscopy (XPS) revealed that a thin and compact SEI layer was formed on the Na metal in [Na(G5)][FSA]/HFE, and the SEI was effective in suppressing the reductive decomposition of the electrolyte.
The charge and discharge properties of hard carbon (HC) anode and Na0.44MnO2 cathode of sodium ion batteries in [Na(G5)][FSA]/HFE electrolyte were characterized. Highly reversible charge-discharge of HC anode was possible in [Na(G5)][FSA]/HFE with a high Coulombic efficiency of 99.9%. In addition, the discharge capacity of HC negligibly decreased during 300 charge-discharge cycles. Na0.44MnO2 cathode also showed highly stable charge-discharge behavior in [Na(G5)][FSA]/HFE owing to the good oxidative stability of the electrolyte.

Acknowledgements

This study was supported in part by the MEXT program “Elements Strategy Initiative to Form Core Research Center” of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan and JSPS KAKENHI (No. 15H03874) from the Japan Society for the Promotion of Science (JSPS).

References

T. Mandai, R. Nozawa, S. Tsuzuki, K. Yoshida, K. Ueno, K. Dokko, M. Watanabe, J. Phys. Chem. B, 117, 15072-15085 (2013).

S. Terada, T. Mandai, R. Nozawa, K. Yoshida, K. Ueno, S. Tsuzuki, K. Dokko, M. Watanabe, Phys. Chem. Chem. Phys., 16, 11737-11746 (2014).

S. Terada, H. Susa, S. Tsuzuki, T. Mandai, K. Ueno, Y. Umebayashi, K. Dokko, M. Watanabe, J. Phys. Chem. C, 120, 23339-23350 (2016).
(Invited) Integration of Thin Film Wavelength Converter on III-V Blue LED
Authors: Kundaliya Darshan , von Malm Norwin , Mishra Kailash C. 
Published: February 2020

The concept of micron-sized emitter (µ-emitter) arrays in a LED chip for advanced displays has been envisioned and realized about a decade and half-ago [1-3]. Since then, these arrays have been fabricated in smaller dimensions of a chip with a very high density. While there has been a significant progress in the fabrication technology of pixelated LEDs of InGaN blue LEDs, there has been scant research addressing the pixelation of LEDs with a phosphor layer for down-conversion of the LED emission.
In this talk, we will describe an approach where an ultra-thin inorganic phosphor layer is fabricated and transferred onto both pixelated as well as non-pixelated LEDs. We will also explain the importance of developing a suitable sacrificial layer while maintaining the desired photoluminescence quantum yield of the phosphor for its successful integration on a LED. It will be shown how important it is to consider the melting temperature, bonding energy, thermal conductivity and optical bandgap of the sacrificial layer to enable successful integration of phosphor thin films to LEDs for solid state lighting applications [4].

S.-X. Jin et al., Appl. Phys. Lett. 76, 631 (2000).

H.X. Jiang et al., Appl. Phys. Lett. 78, 1303 (2001).

H.X. Jiang et al., US Patent 6,410,940 (2002).

D.C. Kundaliya et al., ECS Journal of Solid State Science and Technology, 7, R3046 (2018).
Monitoring Acidithiobacillus Thiooxidans Biofilm Formation on Graphite Surface
Authors: Méndez-Tovar Marcela , García-Meza J Viridiana , González I 
Published: February 2020

Biofilm formation has been studied to understand modifications in electrode interface to create new monitoring devices related with different fields as medical, environmental and industrial. In biomining industry, specifically in bioleaching processes, Acidithiobacillus
thiooxidans is an acidophilic bacterium that enhances bioleaching as it biooxidizes sulfur which normally passivates ores surfaces and diminishes the bioleaching efficiency. In this work, cells of Acidithiobacillus thiooxidans colonized a graphite surface during seven days in acidic culture medium contained elemental sulfur as nutrient, resulting in bioelectrode. In order to monitor the biofilm formation as bioelectrode, microscopic and electrochemical characterization was performed. Confocal laser scanning microscopy images show biofilms formation since first day of graphite immersion in medium, exopolymeric substances (EPS) becomes hydrophobic after 3 days of immersion which is related with lipidic exopolymers, while on day 5 there is an important change in EPS composition resulting in a higher proportion of exopolysaccharides than lipidic substances. This shift on the EPS composition was related to the analysis of EIS spectra obtained for bioelectrodes: An increase of electrochemical resistance of biofilm at the initial 3 immersion days, meanwhile the presence exopolysaccharides decreased such resistance. Cyclic voltammetry characterization of bioelectrodes using culture medium as electrolyte, shows an irreversible reduction process since day 1, which increases in longer exposure times, even when the characterization was performed with agitation. This suggests the reduction process is associated to the adsorbed S0 on graphite bioelectrode. The cathodic peak is near to the calculated reduction potential in acid media (0.1 to 0.2) V vs. NHE. It is known that the sulfur oxidation in acidithiobacilli as A. thiooxidans and A. caldus, initiated via S8 reduction after its activation (protonation) by the GSH and sulfonate (-SH) groups found in an outer-membrane protein [1-4].
M. Méndez-Tovar acknowledges to Universidad Autónoma Metropolitana-Iztapalapa and CONACYT for PhD grant 212534.
References:
[1] Mangold S., Valdés J., Holmes D.S., Front Microbiol, 2011,2,1

[2] Bobadilla R.A., Cortés M.P., Padilla L., Biotechnol. Bioeng., 2013,110, 2242
[3] Yin, H.,Zhang, X., Li X.,BMC Microbiol. 2014,14,179
[4] López‐Cázares I.,Patrón‐Soberano O.A.,García‐ Meza J.V.,Minerals, 2017,7,156

Figure 1
(Invited) Hydrogen Bonding Effects at the Organic-Water Interface of Aqueous Toluene Droplets Investigated By Particle Collision Electrochemistry
Authors: Alvarez Julio C , Paul Dilip K , Meng Kejie 
Published: February 2020

This work reports on the hydrogen bonding effects induced by water solvation in aqueous toluene droplets studied by Particle Collision Electrochemistry (PCE). The latter approach is an emerging methodology employed to characterize microscopic particles that collide with the surface of an ultramicroelectrode as a result of Brownian motion. The ability of PCE to yield in-situ kinetic and thermodynamic information from single collision events has led to fundamental studies of nanoparticle electrochemistry which now is recognized as a sub-field in electrochemistry dubbed as single entity electrochemistry, due to the wide range of probes that can be investigated.
Herein, the reversal of hydrogen bonding affinity between quinone phenolate di-anions (Q2-) and carboxylic acids, induced by water in micrometer-size droplets of toluene is reported. Such an effect is revealed by the two-electron reduction of the hydrophobic quinone (Q) tetrachoro-1,4-benzoquinone to Q2- inside the toluene droplets, when performed in the presence of carboxylic acids that partition differently between the aqueous and organic phases. In bulk toluene, the hydrogen bonding affinity of Q2- for acetic acid (pKa = 4.8) is higher than for oleic acid (pKa = 9.9). However, such trend is reversed in emulsified toluene droplets due to preferential solvation of acetic acid by the surrounding water. The goal of this work is two-fold: first, to illustrate a subtle yet consequential water effect that arises from heterogeneous micro-confinement of organic-water phases, and second, to demonstrate how mechanistic information in such interfaces can be extracted from PCE.
Go in and Go out — Change in Local Structure and Diffusivity in Monoclinic Li3+X
V2(PO4)3 upon Li Insertion and Extraction
Authors: Brinek Marina , Lunghammer Sarah , Hanzu Ilie , Rettenwander Daniel , Wilkening Martin 
Published: February 2020

The use of Li-ion batteries in our daily life has become vital and is going to increase further as the demand for portable energy storage systems will continue to rise in the future. Considering advanced anode and cathode materials a fundamental understanding is needed to visualize the electrochemical processes, local changes in structure and diffusivity upon insertion and extraction of Li ions.
Monoclinic α-Li3+x
V2(PO4)3 (LVP), crystallizing with the space group P21
/n, serves as a very attractive model compound to study these changes. As a chameleon-like electrode material it can be used as both the anode and cathode active material [1]. The Li ions in LVP (x = 0) are equally distributed over 3 crystal sites, which are clearly resolved in high-resolution 7Li magic angle spinning (MAS) nuclear magnetic resonance (NMR). As has been shown earlier by the Goward group [2], 1D and 2D exchange NMR spectroscopy is an excellent tool to identify site-specific ion mobilities and to identify the electrochemically active Li positions. Less attention has, however, been paid to LVP with x > 0. Although the topic has been addressed earlier [2,3], a complete picture about the correlation of local magnetic structures with macroscopic phase transitions is still missing.
Here, we used 7Li MAS NMR, combined with both X-ray and neutron diffraction to throw some light on the changes LVP undergoes during Li uptake and release (− 2 < x < 2). As an example, Li insertion causes a drastic change of the original 7Li NMR spectrum of LVP. For Li3.5V2(PO4) the spectrum recorded at ambient bearing gas temperature consists of at least 4 distinct NMR signals being sharper than those of the starting materials with x = 0. Further increase of x to values larger than 1 reveals a second change leading a quite complex NMR signal with many overlapping lines. For Li3.5V2(PO4) and Li4.0V2(PO4) 2D 6Li MAS NMR will help us to understand the elementary hopping processes in the vanadium phosphate.
Financial support by the Austrian Federal Ministry for Science, Research and Economy as well as the Christian-Doppler Forschungsgesellschaft is highly appreciated.
[1] W.-F. Mao, H.-Q. Tang, Z.-Y. Tang, J. Yan, and Q. Xu, ECS Electrochem. Lett., 2 (7), A69-A71, (2013).
[2] L. S. Cahill, R. P. Chapman, J. F. Britten, and G. R. Goward, J. Phys. Chem. B, 110, 7171-7177, (2006).
[3] C. Liu, R. Massé, X. Nan, G. Cao, Energy Storage Mater., 4, 15-58, (2016).
[4] S.-C. Yin, P. S. Strobel, H. Grondey, L. F. Nazar, Chem. Mater., 16, 1456-1465, (2004).