bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Study on the Electrochemical Characteristics of Kerosene Derived Carbon Nanospheres As Anode Materials of Lithium Secondary Batteries
Authors: Arie Arenst Andreas , Lee Joong-Kee 
Published: February 2020

Spherically shaped carbon materials have been explored for decades, and their characteristics have been applied for instance in the various energy-related industries such as batteries, capacitors or fuel cells. It can be said that the term of carbon spheres refers to all carbon materials that possess a spherical or near spherical shape but do not include the fullerene family of carbons. In general, spherical carbons have been prepared by various methods such as arc discharge, chemical vapor deposition, laser ablation, autoclave process, shockwave process and catalytic pyrolysis process. It can be observed that the different methods can produce carbon spheres with quite different structural and electrical characteristics. In this study, carbon nanospheres (CNSs) were synthesized by the nebulyzed pyrolysis process using kerosene as carbon precursors, ferrocene catalyst and activated carbon support at elevated temperature under an nitrogen atmosphere. Morphology and structure of as grown CNSs were characterized by Scanning Electron Microscope (SEM), High-Resolution Transmission Electron Microscope (HRTEM), Raman and X-ray photo electron spectroscopy. It was found that the carbon products had a turbostratic structures and high degree of disorder carbon structures. Preliminary electrochemical measurements of kerosene derived CNSs as anode materials of lithium secondary batteries were carried out using cyclic voltammetry and charge –discharge tests. Experimental results showed that a stable cycle performances until the 100th cycles was obtained with specific capacity of 400 mAh/g. However, the main problem is the high irreversible capacity at the first cycle due to the low purity and non uniform carbon nano-spheres.
Gas Diffusion Electrodes for Li/O2 Batteries: Impact of Porosity, Wettabiliy and Electrode Design
Authors: Bardenhagen Ingo , Fenske Daniela , Westphal Anne 
Published: February 2020

Beyond lithium ion batteries the metal air technology is considered to be very promising for various energy storage applications in a long-term view. Due to its very high theoretical energy density the aprotic Li/O2 system in particular has attracted broad attention during the recent years. Here molecular oxygen O2 is reduced at a gas diffusion electrode (GDE) upon discharge forming Li2O2 as a solid discharge product which precipitates within the electrode to be reoxidized under the release of oxygen upon recharge. The performance of a Li/O2cell is therefore critically influenced by the structural properties of the used GDE. Based on carbon, especially the porosity, the wetting behavior and the general design of the GDE has a huge impact on the capacity and efficiency of the cell.
Regarding the wettability of a GDE, a thin electrolyte film within the inner pore structure is considered to be ideal to provide efficient oxygen transport through open gas channels as well as improved diffusion properties towards the active surface. Using mesoporous carbon xerogels which exhibit defined open pore structures, large inner surfaces and pore volumes we were able to investigate the pore wettability with different solvents by using 1H relaxation MRT techniques. To investigate them as active material in the Li/O2 system they were synthesized directly into a woven carbon paper to create ready-to-use electrodes without any binder. Here, the discharge reaction was studied by electrical impedance spectroscopy (EIS) using 1M LiTFSI/DMSO as electrolyte and Li metal as reference electrode in a three electrode setup. A model for the interpretation of the limiting factors regarding the GDE performance due to the formation and deposition of the discharge product could be developed. For further investigation of these factors the chemical and morphological characterization of the discharge products in dependence on the GDE design was addressed by XPS analyses. Besides looking at the electrolyte facing side the deposition of discharge product in the bulk of the active layer in the GDE and at the oxygen facing side were investigated. For information about the bulk of the GDE cross-section measurements as well as depth profiling by argon ion sputtering were conducted.
Implications of Metal-Site Vacancies on Li-Ni-Mn-Co Based Positive Electrode Materials
Authors: Shunmugasundaram Ramesh , Senthil Arumugam Rajalakshmi , Dahn Jeff R 
Published: February 2020

One of the key issues with Li-excess positive electrode materials is their high irreversible capacity loss (IRC), which is usually ~ 20 % of their first charge capacity. Li-excess materials with IRC as low as 4% have been recently reported by us1. Those materials were intentionally synthesized with less Li than the stoichiometric amount, based on oxidation state rules, and as a result, metal-site vacancies were found in their single-phase, layered, pristine structures. With metal-site vacancies, the structure can be written as Li[ΔqM(1-q)]O2, where Δ is a metal site vacancy and the transition metal layer has no Li atoms. An elemental analysis of metals only on such materials would conclude they were Li rich because when q > 0, the number of moles of Li is greater than the number of moles of transition metal atoms, even though there are no Li atoms in the transition metal layer. The small IRC was found to be related to the presence of metal site vacancies.
Following that work, a comprehensive search for materials that contain metal-site vacancies was performed in the Li-Ni-Mn-Co pseudo-ternary system. An array of materials with deliberate Li-deficiency and a wide-range of Ni, Mn, and Co compositions was synthesized and their properties were investigated. It was found that, in the Li-Ni-Mn-Co pseudo-ternary system, materials with metal-site vacancies can be synthesized at many Ni-Mn-Co combinations by forcing Li deficiency. Most of the materials were layered single-phase materials but increasing Li deficiency eventually caused the evolution of a spinel phase. The presence of metal-site vacancies were verified by density measurements made with a He-pycnometer. Figure 1 shows the XRD patterns of several single-phase materials (a to f), which have considerable amount of metal-site vacancies, in the range of 20° to 34° representing superlattice ordering between TM ions and vacancies in the TM layer similar to that reported by McCalla et al2. The relative intensity of superlattice peaks varied with overall metal composition (not shown here) suggesting different degrees of ordering. For example, the absence of superlattice peaks in samples e and f suggests that only a negligible amount of vacancies reside in the TM layer whereas the prominent superlattice peaks in samples a and b suggests a significant amount of vacancies in the TM layer. Thus the nature and the relative intensity of the superlattice peaks can be used as a first approximation to predict the location and distribution of vacancies between TM and Li layers. Detailed results on the implications of metal-site vacancies on the properties of Li-Ni-Mn-Co based positive electrode materials will be presented.

References:

Shunmugasundaram, R.; Senthil Arumugam, R.; Dahn, J. R. Chem. Mater.
2015,27, 757–767

McCalla, E.; Rowe, A. W.; Camardese, J.; Dahn, J. R. Chem. Mater.
2013, 25, 2716–2721

Figure 1
A Novel Preparation Procedure of Poly(vinylidenedifluoride)-Based Gel Polymer Electrolyte for Application in Lithium-Ion Batteries
Authors: Fasciani Chiara , Panero Stefania , Hassoun Jusef , Scrosati Bruno 
Published: February 2020

Gel-type polymer membrane electrolytes, GPEs, have attracted particular attention thanks to their low volatility, high thermal stability and safety, which make them suitable for use in lithium ion battery (LIB) technology.1

In this work we present a convenient preparation procedure of poly(vinylidene difluoride) (PVdF)-based gel polymer electrolyte. The novelty of the procedure reported is that the electrolyte is prepared under air as a dry, flexible film and directly gelled during LIB assembly. Therefore, the GPE obtained is easy to handle and suitable for roll-to-roll scaling-up and it can be efficiently used for application in LIB. The morphology and electrochemical interphase properties of the electrolyte have been investigated by scanning electron microscopy and impedance spectroscopy, respectively. Moreover, galvanostatic tests suggested good stability of the lithium electrode/gel electrolyte interface and a high lithium transference number. Finally, cycling tests of full lithium ion cell, employing the GPE, a lithium iron phosphate cathode and a graphite anode confirm the suitability of the GPE for application in stable, low cost and environmentally friendly energy storage systems.2

[1] Croce, F.; Focarete, M. L.; Hassoun, J.; Meschini, I.; Scrosati, B. A Safe, High-Rate and High-Energy Polymer Lithium-Ion Battery Based on Gelled Membranes Prepared by Electrospinning. Energ.
Environ. Sci.2011, 4, 921-927.
[2] Fasciani, C.; Panero, S.; Hassoun, J.; Scrosati, B. (submitted) 2015.

Figure: Scanning Electron Microscopy pictures (background image) of the PVdF-gel membrane and voltage profile at 25°C of a C/GPE/LFP LIB using an activated, pre-lithiated graphite anode. Current rate: C/5; Voltage limits: 3.8 V - 2 V.

Figure 1
Mechanism Scan in Li-O2 Batteries By Impedance Spectroscopy
Authors: Haro Marta , Vicente Nuria , Garcia-Belmonte Germa 
Published: February 2020

Li-O2 batteries are claimed to be the batteries of the future because they can provide the highest energy density among any other type of batteries since Li+ ions and O2 directly react with each other and, in practice, oxygen is not stored in the battery (1). Despite the great deal of attention in this technology currently there exists a great gap between the theoretically achievable energy density and the provided by Li-O2 batteries in practice (2). Therefore, to fully exploit the capacity of Li-O2 batteries, the thermodynamic mechanisms and kinetics that rule and limit their functioning must be understood. In this context, electrochemical impedance spectroscopy (EIS) is a unique technique that allows in-situ monitoring the charge-discharge processes in batteries obtaining kinetic information of the mechanisms developed with different time constant (3). In the present study, the impedance spectra of Li-O2 batteries have been registered at different voltages of the charge and discharge processes. With the obtained data a novel equivalent circuit model is proposed, where interfacial charge transfer, adsorption and diffusion phenomena have been identified as well as the voltages where oxygen reactions (ORR and OER) appear. For each step is associated a resistance what allows to determine the bottleneck process. Furthermore, different parameters (composition and structure) of the cathode have been methodologically modified and the effect on the mechanism step analyzed. The proposed equivalent circuit model is a relevant tool for the rational design of Li-O2 batteries.
References:
(1) N. Imanishi, A. C. Luntz, P. Bruce The Lithium Air Battery: Fundamentals Springer (2013)
(2) N-S. Choi, Z. Chen, S. A. Freunberger, X. Li, Y-K. Sun, K. Amine, G. Yushin, L. F. Nazar, J. Cho, P. G. Bruce Angew. Chem. Int. Ed. 51, 9994 (2012)
(3) F. Martinez-Julian, A. Guerrero, M. Haro, J. Bisquert, D. Bresser, E. Paillard, S. Parrerini, G. Garcia-Belmonte J. Phys. Chem. C 118, 6069 (2014)
Improved Electrochemical Performance of Hydrogenated Li4Ti5O12 As Anode Materials for High-Power Li-Ion Batteries
Authors: Eom Ji-Yong , Yun Ju-Ho , Yoo Seung-Eul 
Published: February 2020

Li4Ti5O12 (LTO) with a spinel structure has received much attention as the most promising alternative to the conventional graphite anode material of Li-ion batteries for hybrid electric vehicle, electric vehicle, and large-scale energy storage applications, due primarily to its advantageous material properties, such as enhanced safety, good capacity retention during cycling, and high power density. Also, LTO is a zero-strain insertion material, which has excellent Li+ insertion/extraction reversibility with no volume change. In spite of these advantages, LTO presents a relatively poor rate capability due to its low electrical conductivity and Li+ diffusion coefficient. Recently, the nanostructured LTO materials coated with carbon-based materials have been extensively studied in the hope of achieving further improvement in the rate capability due to both good electrical conductivity and short Li+ diffusion length. However, these nanomaterials present relatively low volumetric energy density and difficulty in the electrode coating process, and also high production cost. Therefore, it is very important to develop a novel method to achieve simultaneously the enhanced electrical conductivity and volumetric energy density of LTO material.
In this work, we suggest a facile method to achieve the improved electrochemical performance of LTO anode material composed of the micro-sized primary particles for high-power Li-ion batteries. The electrochemical performances of the micro-sized LTO particles, including the rate capability and cycling stability were significantly improved by hydrogenation. The hydrogenated LTO (denoted as H-LTO) particles were obtained by thermal annealing of the P-LTO (denoted as P-LTO) particles at 800 °C for 2~7 h in hydrogen atmosphere. Thermal annealing was performed in a quartz tube furnace filled with ultrahigh purity hydrogen gas. The H-LTO particles exhibited vastly superior the rate capability and capacity retention property during cycling to the P-LTO particles at high current density, since the insertion and extraction of Li+ through the H-LTO particles were preferable to those through the P-LTO particles, which were probably attributed to the short diffusion length for Li+, innumerable reaction sites, and relatively high electrical conductivity.
Synthesis and Electrochemical Characteristics of LiMnPO4/C Composite Materials for Lithium Ion Batteries
Authors: Kang Byeong Su , Kim Kyeong-Joon , Choi Seung-Woo , Kim Min-Young , Yang Seung-Hoon , Lim Jinsub , Lee Moo Sung , Kim Ho-Sung 
Published: February 2020

Olivine-structured LiMnPO4 has attracted broad attention as a potential cathode material of Li-ion battery for EV application [1-2], which has some advantage with a higher energy density, higher redox potential and lower cost, etc. However, this material showed a poor electrochemical performance due to the low electronic conductivity [3-4]. Therefore, many researches have been performed to improve the electrochemical properties of LiMnPO4 material by the particle size reduction, cation doping and carbon coating, etc. [5-6]. In here, we studied nano-sized LiMnPO4/C composite materials with a high crystallization prepared using a modified co-precipitation method including a grinding mill and heat treatment process. As a result, the cell showed a good discharge capacity of 145mAh/g and a discharge potential of 3.8V. Furthermore, as the LiMnPO4/C material was combined with Li2MnO3-based material, the LiMnPO4/C composite materials showed a better electrochemical characteristic of above 200mAh/g at 0.05C. In summary, the nano-sized LiMnO4 material with a high crystallization shows good electrochemical properties at room temperature.

References

[1] J.N. Reimers, J.R. Dahn, J. Electrochem. Soc. 139 (1992) 209.
[2] D.K. Kim, P. Muralidharan, H.-W. Lee, R. Ruffo, Y. Yang, C.K. Chan, H.
Peng, R.A. Huggins, Y. Cui, Nano Letter 8 (11) (2008) 3948–3952.
[3] N.N. Bramnik, H. Ehrenberg, Journal of Alloys and Compounds 464 (2008) 259–264.4)
[4] J. Yang, J.J, Journal of The Electrochemical Society 153 (4) (2006) A716–A723
[5] T. Drezen, N.-H. Kwon, P. Bowen, I. Teerlinck, M. Isono, I. Exnar, Journal of Power Sources 174 (2007) 949–953.
[6] A.V. Murugan, T. Muraliganth, A. Manthiram, Journal of The Electrochemical Society 156 (2) (2009) A79–A83
Thin Film Coatings on Multiwalled Carbon Nanotubes for Lithium-Oxygen Battery Cathodes: Eliminating the Carbon Surface
Authors: Yilmaz Eda , Okur Faruk , Sagkal Sagnak , Eren Hamit , Biyikli Necmi 
Published: February 2020

Energy storage is one of the biggest challenges in our way before switching to sustainable energy resources. Batteries can be a viable solution to this challenge if “better” batteries with higher energy density, improved stability and cheap price can be realized. Lithium-oxygen batteries have become popular recently as they can theoretically offer much higher energy densities compared the widely used Li-ion or Ni-Mh batteries. However, realizing Li-O2 batteries is no easy task, because of the electrolyte decomposition, cathode degradation and anode related problems which were intensively studied in recent years.1,2 These aforementioned problems come together to complicate the electrochemistry taking place inside the cell, consecutively over-potential, low cycling life and poor current rate responses are observed.
In this study thin film coatings of TiO2 are fabricated using atomic layer deposition technique (ALD) on multiwalled carbon nanotubes (MWCNT) and these composites were used as cathode for Li-O2 battery. (Fig.1) Such a structure eliminates the direct interaction of carbon surface with electrolyte molecules and prevents the degradation of carbon cathode without sacrificing the high energy density carbon provides. TiO2 was chosen as the coating material, since in a recent study by Thotiyl et. al. a thin surface film of TiO2 was shown to increase the oxygen reduction and evolution reactions activity of the TiC cathodes.3 The electrochemical properties of the prepared composites and the comprehensive analysis of their effect on degradation mechanisms will be discussed in this presentation.

References

Thotiyl, M. M. O., Freunberger, S. A., Peng, Z., Bruce, P. G., J. Am. Chem. Soc. 2013, 135, 494.

McCloskey, B. D., Speidel, A., Scheffler, R., Miller, D. C., Viswanathan, V., Hummelshøj, J. S., Nørskov, J. K., Luntz, A. C., J. Phys. Chem. Lett., 2012, 3, 997.

Thotiyl, M. M. O., Freunberger, S. A., Peng Z., Chen, Y., Liu, Z., Bruce, P. G., Nat. Mater. 2013, 12, 1050.

Figure 1
Polyethylene Oxide (PEO)-Based Electrolyte for Lithium Sulfur Polymer Battery
Authors: Carbone Lorenzo , Hassoun Jusef 
Published: February 2020

Recently, innovations in the field of energy storage, requiring high capacity and efficiency triggered large number of studies on new systems such as batteries lithium-air and lithium sulfur. These new technologies may lead to significant advances and application as power sources in hybrid electric vehicles (HEVs), plugged-in hybrid vehicles (PHEVs), full electric vehicles (EVs) [1]. Lithium sulfur battery represents the most suitable candidate due to its promising characteristics in terms of specific capacity (1675 mAh g-1) and energy density (3500 Wh kg-1).
However, the Li-S electrochemical process leads to the formation of various polysulfide, i.e. species soluble in the common electrolytes, thus causing parasitic reaction and shuttle effects [2]. Furthermore, electrolytes such as carbonate have low thermal stability and flammability issues [3]. Hence, the study of electrolytes capable of supporting the high performance of the new electrode materials and the associated problems is necessary to optimize the cell performances. In this scenario, the ideal candidate for the use in the new generation of batteries is the polyethylene oxide-based electrolyte [4]. Herein, we report the characterization of a PEO-based membrane using LiCF3SO3 as the lithium-ion salt. The electrolyte, considered as suitable media for lithium-sulfur battery and characterized by high safety level, has been studied in terms of thermal properties (TGA, DSC), lithium ion conductivity, lithium interface stability, lithium transference number and cyclic voltammetry. Finally, a lithium-sulfur cell using the selected electrolyte has been efficiently investigated, by galvanostatic charge-discharge test, evidencing promising results in terms of delivered capacity and stability (see figure below reporting a typical charge discharge cycling profile of the studied lithium-sulfur polymer cell).
(Figure reports typical charge discharge cycling profile of the studied lithium-sulfur polymer cell)

Acknowledgements

This work was supported by Sapienza University-Volkswagen AG joint project

References

[1] R. Bernhard, A.Latini, S. Panero, B.Scrosati, J. Hassoun. Journal of Power Sources 226 (2013) 329-333
[2] Sheng S. Zhang Journal of Power Sources 231 (2013) 153e162
[3] Nagasubramanian, G. , Fenton, K. 101 (2013) 3-10
[4] F. Croce, R. Curini, A. Martinelli , L Persi , F. Ronci e B. Scrosati J. Phys. Chem. B 1999, 103, 10632-10638

Figure 1
Electrochemical Characteristics of Si/C/CNT Composites for Anode Material of Lithium Ion Battery
Authors: Lee Jong Dae , Jung Min Zy 
Published: February 2020

In recent years, lithium ion battery has been widely used on portable electronic devices and electric/hybrid vehicles because of its high energy density and cycling stability. As an anode material for the lithium ion battery, Silicon(Si) is getting attention for its high theoretical specific capacity (about 4200mAh/g) and its proper potential range for lithium insertion and extraction. However, Si has properties that could be obstacles for its practical use as the lithium ion battery anode. Si not only has a low intrinsic electric conductivity but also undergoes severe volume changes during the lithium ion insertion/extraction process which results in pulverization of the electrode materials, causing the capacity to fade. To overcome these problems and enhance the electric conductivity, we synthesized Silicon/Carbon/CNT composites as an anode material. Si/C/CNT composites were prepared by the fabrication processes including the synthesis of SBA-15, magnesiothermic reduction of SBA-15 to obtain Si/MgO by ball milling, carbonization of phenolic resin with CNT and HCl etching. The prepared Si/C/CNT composites were analysed by BET, XRD, FE-SEM and TGA. Among the SBA-15 samples synthesized with reaction temperatures between 50°C and 70°C, the SBA-15 of 60°C showed the largest specific surface area. Also the electrochemical performances of Si/C/CNT composites as the anode electrode were investigated by constant current charge/discharge test, cyclic voltammetry and leakage tests in the electrolyte of LiPF6 dissolved in organic solvents(EC:DMC:EMC=1:1:1 vol%). The coin cell using Si/C/CNT composite(Si:CNT=97 :3 in weight) has better capacity(1,440 mAh/g) than that of other composition coin cells. Also, it is found that Si/C/CNT composite(Si:CNT=97:3 in weight) electrode shows improved cycling performance and electric conductivity.