bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of Surface Polyanions on the Lithium-Excess Layered Cathode
Authors: Xu Guofeng , Li Jianling , Wang Xindong 
Published: February 2020

The lithium-excess layered cathode materials Li1+xM1-xO2 or xLi2MnO3·(1-x)LiMO2 (M is a transition metal or a mixture of transition metals) are quite promising due to the reversible capacity of up to 280 mAh g-1 and the wide working voltage range and low cost. There are some drawbacks to overcome for the further application of lithium-rich cathode although extensive researches have been carried out. The large irreversible capacity loss during the initial cycle has a significant impact on the subsequent charge and discharge capacity. The mechanisms of lithium transference and structure evolution during the initial and succeeding cycles require further investigation. The cathode exhibits awful rate capability because of the existence of the low electronic conductivity ingredient Li2MnO3. In addition, the cathode also presents a gradual capacity drop by reason of local phase transformation during cycling.
The high capacity of ＞250 mAh g-1 only occurs when the voltage exceed 4.5 V and the 4.5 V platform is related to the oxidation of lattice O. The gas phase oxidation product releases from the material along with the migration of transition metal element and the resulted evolution of crystal structure. Considering the oxygen release and ion migration happened firstly at the surface of the material particles, the polyanions contains F are adopted to treat the surface of Li1.2Co0.13Ni0.13Mn0.54O2 in order to stabilize the crystal lattice. The treated materials show better electrochemical performance and the mechanism is analyzed in detail.
Study of the Structural and Thermal Stabilities of Chemically Deintercalated Phases of NMC Type Positive Electrode Materials for Lithium Ion Batteries
Authors: El Mofid Wassima , Ivanov Svetlozar , Bund Andreas 
Published: February 2020

Given the importance attributed to safety aspects of advanced lithium ion batteries [1-4], the structural and thermal stabilities of the active materials are of great importance. The main focus of our work is a double substituted Ni-rich NMC material LiNi0.6Mn0.2Co0.15Al0.025Fe0.025O2 (NMCAF), which has been recently reported as a material with good electrochemical performance, improved cycleability and capacity retention [5]. For comparison we also studied a pristine NMC material with the stoichiometry LiNi0.6Mn0.2Co0.2O2.
The materials chosen for this study were synthesized by the self-combustion method. The preservation of the α-NaFeO2 type layered structure after metal substitution was confirmed by X-ray diffraction.
In order to study the structural effects at different lithiation states a chemical deintercalation at room temperature based on a non-aqueous NO2BF4 / acetonitrile solution has been performed..
The X-ray patterns of the deintercalated phases showed a continuous displacement of the diffraction lines with the extraction of lithium ions, accompanied by broadening of the diffraction peaks. Both systems have been subsequently the object of thermal characterisation by means of thermogravimetric analysis (TGA), in order to assess the heating effect on the structural stability. .The results displayed continuous mass losses between 100 ° C and 600 ° C for both materials, most probably corresponding to oxygen release. The observed thermal instability can cause a serious safety issues due to exothermic reaction of the released oxygen with the electrolyte. This process can affect the cycle life and even the safety of the battery [6].
Comparing TGA results for both materials, the non-substituted NMC displayed higher weight loss related to pronounced thermal instability. These results evidenced once more the stabilizing effect of the double substitution of Co with Al and Fe in the pristine NMC material.

References

[1] Dan Doughty, E. Peter Roth, The electrochemical society interface (2012) 37-44.
[2] E.P Roth, D.H Doughty, J. Power Sources 128 (2004) 308-318
[3] Diego Lisbona, Timothy Snee, Process Safety and Environmental Protection 89 (2011) 434-442.
[4] P.G. Balakrishnan, R. Ramesh, T. Prem Kumar, J. Power Sources 155 (2006) 401-414
[5] W. El Mofid, S. Ivanov, A. Konkin, A. Bund, J. Power Sources 268 (2014) 414-422.
[6] J. R. Dahn, E. W. Fuller, M. Obrovac, U. Von Sacken, Solid State Ionics 69 (1994) 265-270.
Understanding of the Polyacrylic Acid Role As Efficient Binder in Silicon Based Electrode for Li-Ion Battery
Authors: Porcher Willy , Chazelle Sophie , Mariage Nicolas , Boulineau Adrien , Haon Cédric , Bridel Jean-Sébastien , Van Rompaey Tim 
Published: February 2020

Silicon is a promising material at the negative electrode due to its huge specific capacity and its low potential. Nevertheless, silicon undergoes also huge volume changes upon alloying and de-alloying with lithium; up to +300%. Among the material design or the electrolyte composition, the role of the binder is also critical to obtain a good cycle life.
Several studies have reported that polyacrylic acid (PAA) would be a suitable binder for silicon composite electrode [1-3]. However, little is known about its behavior.
In this study, we have evaluated firstly in the framework of a design of experiments (DOE), silicon based electrodes integrating PAA binder with different molecular weights, proportions and pH. The first irreversible capacity and the mean coulombic efficiency upon cycling were the parameters studied in this DOE. We have confirmed in fact that PAA, when appropriately used, was an efficient binder in silicon based electrode compared to other binders as carboxymethyl cellulose (CMC) or polyether imide (PEI).
In addition, we have tried to understand PAA behavior, compared to CMC and PEI, based on the interactions of binder/silicon into the slurries, the binders distributions into the electrodes (Figure 1), the binders mechanical properties and electrodes thickness measurements at different states of charge after different cycles. All these characterizations allow better understanding of the binder role in silicon electrodes.
Figure 1: a) c) TEM images and b) d) STEM EELS mapping (Si: green; C: red) of Si based electrodes coated with a) b) PAA and c) d) CMC as binder
[1]: A. Magasinski, B. Zdyrko, I. Kovlaneko, B. Hertzberg, R. Burtovyy, C. F. Huebner, T. F. Fuller, I. Luzinov and G. Yushin, ACS Appl. Mater Interfaces, 2, 3004 (2010).
[2]: V. L. Chevrier, L. Liu, D. Ba Le, J. Lund, B. Molla, K. Reimer, L. J. Krause, L. D. Jensen, E. Figgemeier and K. W. Eberman, J. Electrochem. Soc., 161, A783 (2014).
[3]: Z.-J. Han, K. Yamagiwa, N. Yabuuchi, J.-Y. Son, Y.-T. Cui, H. Oji, A. Kogure, T. Harada, S. Ishikawa, Y. Aokid and S. Komaba, Phys.Chem.Chem.Phys., 17, 3783 (2015).

Figure 1
Laser Pyrolysed N-Doped SnOx Nanoparticles with Enhanced Conductivity and Stability As Anode in Li-Ion Batteries
Authors: Wang Luyuan Paul , Zhao Yi , Wei Chao , Leconte Yann , Srinivasan Madhavi , Xu ZhiChuan, Jason 
Published: February 2020

A novel one-step laser induced pyrolysis method was utilized for the synthesis of pristine SnO2 and p-type conduction N-doped SnOx nanoparticles. Most reports on doping of SnO2 focuses on subtition of Sn with other metallic, while replacement of O is uncommon due to difficulty in synthesis. In particular, laser pyrolysis made the synthesis of N-doped SnO2 possible by the high thermal gradient between the reaction zone and chamber wall to limit particle growth, as well as a brief contact of N atoms and SnO2 under extermely high temperature. The presence of N atoms during the rapid synthesis process substitutes the O2- anion and is hypothesized to improve conductivity of the material. The sample with 3% of N-doping exhibited optimum performance, with high initial and reversible capacities of 1899 and 1241 mAh g-1 respectively. Even when tested at a current density of 10 A g-1, SnO2+N3% can deliver a specific capacity as high as 522 mAh g-1. Moreover, a capacity of 1192 mAh g-1 can be retained at end of the 500th cycle. The cyclability and rate performance of the carbon free SnO2 nanoparticles are by far one of the best reported thus far. Interestingly, SnO2+N8% demonstrated the worst rate capability, which indicates that there could be an optimum doping concentration. The superior performance in SnO2+N3% could be credited to the presence of hole donating N atoms directly situated within the structure of SnO2 and the small particle sizes which permits rapid ion diffusion while preventing pulverization and agglomeration. Ex-situ TEM and XAS will be utilized to further understand correlation between structural properties with enhancement in performance.

Figure 1
Solution Combustion Synthesis of Transition Metal Oxide-Carbon Composite for Li Ion Battery Anode
Authors: Zhu Chunyu , Aoki Yoshitaka , Habazaki Hiroki 
Published: February 2020

Lithium ion batteries (LIBs) have attracted attentions as one of the most promising power sources for application in portable electronic devices and electric vehicles because of their high energy density and long life span. As for the pursuit of the next generation high-capacity LIBs, transition metal oxides (MOx, M = Fe, Mn, etc.) have been investigated as improved negative materials because of their higher theoretical capacities (>700 mA h g-1) than commercial graphite (372 mAh g-1). However, practical application of MOx in LIBs has been hindered by the poor cycling performance and low rate capability owing to its poor electrical conductivity and large volume expansion/shrinkage during the Li insertion/extraction processes. Compositing of the nanosized oxide with carbon materials can effectively enhance the cycling performance. The carbon matrix could effectively enhance the electrical conductivity of oxides and alleviate the change in volume arising from lithium insertion/extraction.
Solution combustion synthesis (SCS) is a highly exothermic and self-sustaining reaction process by heating a solution mixture of aqueous metal nitrates and organic fuels. A variety of functional oxides, such as perovskite oxide catalysts and cathode oxide materials for LIBs has been synthesized by this method. This method offers several benefits, such as (1) the utilization of an exothermic reaction requiring no additional energy during the combustion process, (2) larger surface areas of nanosized or porous products, (3) homogeneous doping of trace amounts of various elements in a single step. By controlling the combustion reaction conditions to avoid the complete combustion of the carbonaceous material, the remaining carbon material and metal oxides can form composites for advanced LIB anode materials. This can be achieved by (1) adding excess amount of fuel and (2) adding carbon additives and performing the SCS under inert atmosphere.
In this study, we present the facile production of MOx/carbon composites by SCS. The composition, phase structure and morphology of the composites are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and scanning and transmission electron microscopy. The results indicate that MOx nanocrystals are uniformly embedded in the carbon matrix. The composite materials exhibit high discharge/charge capacities, superior cycling performance, and good rate capability. The easy production and superior electrochemical properties enable the composites to be promising candidates as anode alternatives for high-performance LIBs.
References:
RSC Advances, 2015. 5(27): 21066-21073.
Journal of Alloys and Compounds, 2015. 633(0): 424-429.
International Journal of Hydrogen Energy, 2013. 38(30): 13238-13248.
Bismuth Thin Films As Anodes for Low Voltage All-Solid-State Li-Ion Batteries
Authors: Pecquenard Brigitte , Galipaud Jules , Cotte Stéphane , Le Cras Frédéric 
Published: February 2020

The fast-growing market of portable electronic systems, generally battery-powered, has triggered the race for the development of high-performance microprocessors and Systems-on-a-Chip (SoCs) using low power consumption integrated circuits. As a consequence, the energy supply of such optimized components can also be ensured today by miniaturized power sources such as microbatteries (whose capacities range from 1 to 100 µAh). All-solid-state lithium microbatteries can interestingly be manufactured by vacuum deposition processes, also widely used in the microelectronics industry, and they do not to contain a liquid electrolyte, that is beneficial to safety [1]. The association of microelectronic components and microbatteries is going to give birth to new products within three main domains: back-up power for Dynamic Random Access Memory (DRAM) or Real-Time-Clocks (RTC), embedded energy and autonomous devices. Besides, the supply voltage required to operate electronic chips has steadily decreased during the last decades and is now lower than 2V. As a consequence, contrary to conventional Li-ion batteries, low to moderate voltages are preferred for lithium microbatteries. The latter can be achieved by using either a low voltage cathode [2] or a high voltage anode with an adapted Li-ion microbattery design [3].
Bismuth undergoes electrochemical alloying with lithium around 0.8 V/Li+/Li. The formation of LiBi, then of Li3Bi through biphasic reactions results in two perfectly defined voltage plateaus [4] and a theoretical volumetric capacity of 377 µAh.cm-2.µm-1. Thus, this electronically conductive and non-toxic element is an attractive anode material for Li-ion microbatteries. Nevertheless, until now, no sufficient reversibility of the reaction was ever achieved (in liquid electrolyte) [5] and the deposition of only rough Bi thin films incompatible with an integration in microbatteries was reported in the literature [6]. This presentation will therefore focus on the optimization of sputtering conditions to obtain pure and smooth Bi thin film electrodes (Ra ≈ 40nm), then on their electrochemical behavior in liquid electrolyte and for the first time on their final performance in all-solid-state Li/LiPON/Bi thin film batteries.
References:
[1] B. Fleutot, B. Pecquenard, F. Le Cras, B. Delis, H. Martinez, L. Dupont, D. Guy-Bouyssou, J. Power Sources, 196 (2011) 10289
[2] V. Pelé, F. Flamary, L. Bourgeois, B. Pecquenard, F. Le Cras, Electrochem. Comm., 51 (2015) 81
[3] F. Le Cras, B. Pecquenard, V. Dubois, V.P. Phan, D. Guy-Bouyssou, Adv. Energy Mater., 5 (2015) 1501061
[4] J. Wang, I. D. Raistrick, R.A. Huggins, J. Electrochem. Soc., 133 (1986) 457
[5] O. Crosnier, T. Brousse, X. Devaux, P. Fragnaud, D.M. Schleich, J. Power Sources, 94 (2001) 169
[6] D.H. Kim, S. H. Lee, J. K. Kim, G. H. Lee, Appl. Surf. Sci., 252 (2006) 3525
Effect of Iodination Temperature on the Polyvinyl Alcohol Based Carbon Nanofiber for Lithium Ion Battery Anodes
Authors: Serife Pampal Esra , Stojanovska Elena , Kucukkalfa Serra , Uzun Davut , Yilmaz Safak , Kilic Ali 
Published: February 2020

Nanofibers has broad application areas including energy, filtration, biomedical and many other engineering fields due to their high porosity, high surface area to volume ratio. Researchers studied several materials and production methods in order to obtain different superior properties from nanofibers.
Recently, lithium ion batteries has achieved huge importance due to growing demand for portable electronics, electric vehicles and grid energy storage,etc. Batteries have different components among them anodes have crucial importance on the battery capacity, cycle life and rate capability. One of the promising 1D anode material as carbon nanofibers can provide fast electron transport, reduced lithium ion diffusion lenghts and enhanced surface area comparing to commercial electrodes.
There are several carbon nanofiber precursors, such as polyacrylonitril(PAN), lignin, pitch, polyimide(PI).. etc. among them polyvynil alcohol has important advantage because of their environmentally friendly, water soluble and low cost properties. Polyvinyl alcohol (PVA) is a water-soluble polyhydroxy polymer with a broad range of industrial and technical applications. It has been used as a carbon precursor or directly used as anode, cathode or separator in Li-ion batteries. PVA based carbon nanofibers can be easily obtained by electrospinning and subsequent carbonization PVA might be an environmentally friendly alternative material for PAN based carbon fibers. However rather than oxidative stabilization in PAN based precursors, linear PVA chains must be stabilized via other suitable processes. There are various routes that have been proposed to suppress the thermal degradation of PVA before carbonization step, such as using HCl, H2SO4, NH4 vapour or chemical impregnation into different salts. Stabilization of PVA under iodine vapour is a promising approach with high carbon yield for obtaining carbon nanofibers.
In this study, we investigated the effect of iodination temperature on the morphology, chemical structure, and electrical properties of carbon nanofiber webs fabricated from electrospun PVA nanofibers. Obtained nanofibers were subjected to different iodination temperature and then converted into carbon nanofibers. It was found that increasing the iodination temperature provides higher carbon yield. Carbon nanofibers were used as binder free, self- standing anode for lithium ion battery. Battery performances showed that PVA based carbon nanofibers are promising anode materials for lithium ion batteries.
Si-Based Ge and GeSn Material Epitaxy and Thermal Stability Characterization
Authors: Xue Chunlai , Zhang Xu , Cong Hui , Cheng Buwen , Wang Qiming 
Published: February 2020

_In the past decade, Si photonics has become one of the hottest research topics in the world since it holds great promise for maintaining the performance roadmap known as Moore’s law. The application of silicon photonics technologies to requires the development of high quality Si-based materials for photonics devices monolithically integrated to a Si platform. Germanium (Ge), due to its large absorption coefficient at near-infrared frequencies, and its lower cost and compatibility of parallel processing with silicon compared to III-V semiconductors, is perceived as the best candidate for on-chip photodetectors. Meanwhile, Ge is a pseudo-direct bandgap material because its direct Γ-valley CB is just 136.5 meV above the lowest L-valley CB at room temperature . This energy difference can be effectively reduced by incorporating Sn, another group-IV element, into Ge to modulate the band structure. GeSn alloy has been proven to be another promising material for the Si-based laser and PDs covering all telecommunication windows.
In this presentation, Ge 、GeSn and GeSn/Ge MQW have been grown on Si, Ge/Si and Ge. The crystallinity and growth quality of the Ge and GeSn films were investigated through material characterization methods including x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, and transmission electron microscopy. In order to grow GeSn on Si and Ge subtrate,the growth is performed at low temperature, but the devices fabrication process will be carried out at high temperature, so the stability study is important. The effect of rapid thermal annealing on the conversion of metastable elastically strained GeSn layers into a plastically relaxed state is also examined. the results show that GeSn alloy have good thermal stability at 500℃if Sn contents are as low as ~3%. The stability of the GeSn/Ge MQW structure is temperature-dependentand and the temperature over 400℃ should be avoided to guarantee the structural integrity of the MQWs.
Physics of Metal/Ge Interfaces; Interface Defects and Fermi-Level Depinning
Authors: Nakayama Takashi , Sasaki Shogo , Asayama Yoshihiro 
Published: February 2020

Germanium (Ge) has high carrier mobility compared to Si and is expected again to work as a promising key material in next-generation high-speed energy-saving devices. With respect to metal/Ge interfaces, however, there still exist serious issues to be overcome for applications; one which is the control of interface disorders and Schottky-barrier height (SBH). In this work, we discuss this issue based on fundamental properties of metal/Ge interfaces evaluated by theoretical calculations.
It is well known that a variety of metal/Ge interfaces show a strong Fermi-level pinning (FLP); the Fermi energies of various metals are located at similar energy positions around the valence-band edge of Ge irrespective of the kind of metal, which induces the difficulty in controlling the SBH by simply changing the kind of metal. By the first-principles calculations, we found that this FLP is caused by the small band gap of Ge and the long penetration depth of metal-induced gap states (MIGS) into Ge layers even at clean interfaces [1]. Moreover, by evaluating the formation energies of various defects and dynamical atom motions around the interface, we showed that the MIGS are well hybridized with electronic states of defects and become the leading actors to increase the interface disorders (See Fig.1 in attached file for the case of vacancy defect in Ge layers). This result indicates important concept that the MIGS promote the disorder-induced gap states (DIGS). Correspondingly, even at weakly FL-depinned Fe3Si/Ge interface, the interface defects also promote the FLP [2].
One of recipes to release the FLP is to insert the third materials into the interfaces by the segregation of dopant atoms such as S and P, similar to the cases of metal/Si interfaces [3], and by the stacking of transition layers made of semiconductor/oxide. For example, we found that the appearance of ultrathin semiconducting α-Sn layers between metallic β-Sn and Ge layers works to increase the SBH for hole carriers, in agreement with recent experiments. Similarly, when GeO2 oxide is produced between metal and Ge layers, the MIGS penetration into Ge layers is prohibited and the SBH increases to the original position (See Fig.2 in attached file for the case of Al/Ge interfaces).
These results are discussed in details, together with reviewing recent experiments and focusing on the fundamental physics at metal/Ge interfaces.
<references>
[1] T. Hiramatsu et al., Jpn. J. Appl. Phys. 53, 058006 (2014).
[2] K. Kobinata and T. Nakayama, Jpn. J. Appl. Phys. 53, 035701 (2014).
[3] T. Nakayama and K. Kobinata, Thin Solid Films 520, 3374 (2012).

Figure 1