bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphorus-Based Negative Electrode Materials for Na-Ion Batteries
Authors: Kim Youngjin , Oh Seung M. , Choi Aram , Lee Kyu Tae 
Published: February 2020

Introduction

Na-ion batteries have recently received a lot of attention as a next-generation battery, because Na resources are inexhaustible and cheaper than Li resources. However, although Na-ion batteries have shown promising electrochemical performance including stable cycle performance and good rate performance, it should be mentioned that it is not easy for Na-ion batteries to replace Li-ion batteries owing to the critical issue of Na-ion batteries having slightly lower energy density than Li-ion batteries. Therefore, in order to successfully replace Li-ion batteries by Na-ion batteries, new anode materials having a high reversible capacity should be introduced. In this presentation, phosphorus-based negative electrode materials are introduced for Na-ion batteries. Phosphorus-based electrodes showed excellent electrochemical performance including a high reversible capacity (>700 mAh/g), excellent cycle performance, and an ideal redox potential (< 0.4 V vs. Na/Na+), thus making it a promising candidate for Na ion batteries.

Experimental

Two types of phosphorus-based active materials were prepared as follows. For red phosphorus/carbon composites, phosphorus powder and Super P carbon were mixed in a 7:3 weight ratio using a high energy mechanical ball-milling method. For the synthesis of tin phosphide, phosphorus and Sn powders were mixed using the same ball-milling method.
Samples of active materials were mixed with carbon black (Super P) and polyacrylic acid (PAA) in a 7:1:2 weight ratio. The electrochemical performance was evaluated using 2032 coin cells with a Na metal anode and 1 M NaClO4in ethylene carbonate and diethyl carbonate (1:1 v/v) with or without the addition of 5% fluoroethylene carbonate (FEC).
For the analysis of the reaction mechanism, ex-situ X-ray diffraction (ex-situXRD), high resolution transmission electron microscope (HR-TEM) and X-ray absorption spectroscopy (XAS) analysis were performed.

Results and Discussion

The amorphous red phosphorus/carbon composite exhibited promising electrochemical performance including i) high reversible capacity of 1890 mA h g-1 (equivalent to 2.18 mol of Na alloyed with one mole of P); ii) good cycle performance over 30 cycles; and iii) appropriate redox potential of ca.0.4 V vs. Na/Na+.
Also, tin phosphide electrode showed excellent electrochemical performance including i) high reversible capacity of about 718 mA h g-1; ii) negligible capacity fading over 100 cycles in spite of the large particle size (> a few micrometer).
Finally, the reaction and failure mechanisms of both electrodes were studied using ex situ instrumental analysis.

References

[1] Y.Kim, Y. Park, A. Choi, N.S. Choi, J. Kim, J. Lee, J.H. Ryu, S.M. Oh, K.T.Lee, Adv. Mater.
25(22) 3045 (2013).
A Silicon/Graphene Composite Anode for High-Efficiency Lithium Batteries
Authors: Nobili Francesco , Maroni Fabio , Raccichini Rinaldo , Tossici Roberto , Marassi Roberto 
Published: February 2020

Composite anodes based on Si and reduced graphene oxide (RGO) have been prepared using commercial Si nanopowder, graphene oxide (GO) and polyacrilic acid (PAA) as starting materials. A double reduction step, consisting in microwave irradiation at mild power followed by thermal annealing in reducing atmosphere, yielded the composite powder made of Si:reduced graphene oxide (RGO) in the approximate mass ratio 30:70. The charge/discharge properties of the anode materials are determined by the homogeneous dispersion of Si grains between RGO nanosheets, that act as structural buffer for volume changes related to Li-Si reversible alloying and as improved electrical conductor. Electrodes have been prepared using high-molecular weight PAA as binder, which promises better mechanical stability towards silicon volume changes. The electrochemical behavior of the composite anode material has been characterized by galvanostatic cyclations and electrochemical impedance spectroscopy, using LiPF61M in EC:DMC 1:1 electrolyte, also modified by the addition of 5% vinylene carbonate (VC).
Several anodes have been investigated, consistently delivering reversible capacities higher than 1000 mAhg-1, with a mechanism that, after initial lithiation of crystalline Si, mainly involves reversible Li-Si alloying/dealloying between amorphous a-Li and a-LixSi phases. Particularly, when cycled in VC-modified electrolyte the anode exhibits a remarkable cycle life, resulting in a residual capacity of more than 900 mAhg-1 after 60 cycles at 500 mAg-1 and efficiency values close to unity. Several factors concur in determining this behavior, namely: (i) the efficient Si dispersion in RGO carbonaceous matrix; (ii) the good mechanical properties of PAA binder; (iii) the formation of a stabilized SEI by VC additive in the electrolyte.
Amorphous Columnar Silicon Anodes with Excellent Cycling Stability for Advanced High Voltage Lithium Ion Full Cells: Dominant Factors Governing Cycling Performance
Authors: Aurbach Doron , Markevich Elena , Salitra Gregory , Fridman Katia , Elazari Ran , Sharabi Ronit , Garsuch Arnd , Lampert Jordan 
Published: February 2020

An excellent cycling stability of monolithic amorphous columnar silicon electrodes with the loqading of 1.3 mg/cm2 in fluoroethylene carbonate (FEC)-based electrolyte solutions was demonstrated. The effect of the electrolyte solution composition and the cycling protocol on the long-term cycling performance and surface chemistry of amorphous silicon electrodes was investigated using electrochemical tools, XPS, SEM and EDS. It relates to the ability of FEC to form polyenes, as well as to a high rate of HF formation in its water contaminated LiPF6 solutions, measured by 19F NMR spectroscopy. We found that excellent passivation in FEC solutions related to a low content of oxygen containing moieties species (e.g. organic and inorganic carbonates, alkoxides, oxygen-containing organic polymers) in surface films.
Galvanostatic tests and spectroscopic analyses revealed also a strong dependence of the composition and properties of the surface films on amorphous Si electrodes on the cycling procedure. Charge limited galvanostatic cycling procedure including repeated deep discharge of Si electrodes down to 10 mV vs. Li/Li+in every cycle from the very beginning of the electrodes life, ensures the formation of thin and highly passivating surface films on their surface and good cycling performance. To the contrary, when a limited portion of the capacity of Si electrodes during cycling relates to the higher potential range (discharge limited protocol), surface films enriched with oxygen containing species are formed. Their passivating properties are less effective compared to the other composition discussed above (polyenes + LiF).
Cycling stability of Si electrodes in LiPF6solutions decreases in the following order FEC/DMC > 3,4-trans-difluoroethylene carbonate (DFEC)/DMC > ethylene carbonate (EC)/DMC > propylene carbonate (PC).
Amorphous columnar silicon electrodes were combined with high voltage LiNi0.5Mn1.5O4 spinel and LiCoPO4/C composite cathodes and high specific capacity xLi2MnO3
.(1-x)LiNiyMnzCo1-y-zO2 cathodes. These batteries demonstrated excellent performance in term of cycle life, charge-discharge efficiency and good rate capability.
A New, Rapid Approach for the Synthesis of Germanium Nanowire Based Li-Ion Battery Anodes and Their Excellent Performance over Extended Cycles
Authors: Mullane Emma , Kennedy Tadhg , Ryan Kevin M 
Published: February 2020

Ge nanowires (NWs) have recently been highlighted as active materials for Li battery anodes.1,2 Ge NWs (along with Si NWs2,3) are well placed as anode materials for Li-ion storage due to their high theoretical capacity of 1384 mAhg-1. The diffusion of Li within Ge is some 400 times faster than in Si1 meaning that Ge is particularly suited to high power rate anodes. To maximize the capacity of NW based Li-ion anodes, they should be grown in high density directly on the metal current collector to allow for efficient current transport. Ancillary materials such as inactive catalyst seeds, binders and conductive additives should also be minimised as they diminish capacity by adding mass to the final device. Herein we present the development of a rapid pyrolysis route4 allowing the formation of high density Ge NW mats grown directly on stainless steel current collector substrates with reactions taking < 30 seconds (Figure 1 a). The growth system exploits the in-situ formation of discrete Cu3Ge catalyst seeds from a thermally evaporated Cu layer producing centimetre scale NW coverage on device integrable substrates. Electrochemical testing of the NW covered substrates yielded capacity measurements greater than 1000 mAhr-1g after 1000 cycles with a Coulombic efficiency of 99.7 % (Figure 1 b). The NW based anodes showed high-rate stability with discharge capacities of 800 mAhg-1cycled at a rate of 10C. The method represents a rapid scalable approach for the formation of highly promising Li-ion anode materials.
1. Candace K. Chan, Xiaou Feng Zhang, Yi Cui, Nano Letters
2007, 8, 307-309
2. Mullane, E.; Kennedy, T.; Geaney, H.; Dickinson, C.; Ryan, K. M. Chemistry of Materials
2013, 25, 1816.
3. Candace K. Chan, Peng Hailin, Gao Liu, Kevin McIlwrath, Xiao Feng Zhang, Robert A. Huggins, Yi Cui, Nature Nanotechnology
2008, 3 (1), 31-35
4. Mullane, E.; Geaney, H.; Ryan, K. M. Chemical Communications
2012, 48, 5446.
Influences of Dopants on the Properties of LiMnO2 and Li2MnO3 in OLO Cathode for Li Ion Batteries
Authors: Kong Fantai , Longo Roberto C , Park Min-Sik , Yoon Jaegu , Yeon Dong-Hee , Park Jin-Hwan , Wang Weihua , KC Santosh , Doo Seok-Kwang , Cho Kyeongjae 
Published: February 2020

The over-lithiated-oxides (OLOs), a composite of layered structures of Li2MnO3 and LiMO2 (M = Mn, Fe, Co, Ni), have shown much higher storage capacity than the traditional layered oxides for Li ion battery cathode because of the Li2MnO3 phase. However, Li2MnO3 is not stable after the 1st charge-discharge cycle and will partly transform into layered LiMnO2, which indicates that the practically used phase is a mixture of both Li2MnO3 and LiMnO2. During the subsequent cycles, the OLO voltage decreases due to the phase transition of layered LiMnO2 into spinel. Experimentally, the effective dopants satisfying multiple cathode materials requirements of thermodynamic stability, optimized voltage and improved kinetics based on ionic and electronic conductivities are investigated to overcome the voltage degradation and to improve the power capacity. In this work, redox potential, lithium ion diffusion and charge carrier transportation of both phases are examined in details using the ab initio density-functional theory (DFT) simulations. The calculations find, due to the Jahn-Teller effect of Mn3+ atoms, Li vacancy migration in LiMnO2 has special behaviors and hole polaron and electron polaron will form in LiMnO2 and Li2MnO3 phases, respectively. Based on the understanding of the pure phase properties, the effects of 10 cationic (Mg, Ti, V, Nb, Fe, Ru, Co, Ni, Cu, Al) and 2 anionic (N, F) dopants on the redox potential, ionic and electronic conductivity are investigated. These DFT findings could provide conceptual guidance in the experimental search for the effective dopants enabling the practical application of OLO cathodes.
This work was supported by Samsung GRO project.
Effect of Particle Morphology on the Cycle Life of LiNixCoyMn1-x-YO2 Electrode in Li-Ion Cell
Authors: Valikangas Juho Pekka , Lassi Ulla , Hu Tao , Rasanen Samuli 
Published: February 2020

LiCoO2 is one of the widely used cathode material in portable Li-ion batteries. Cobalt is expensive metal, therefore it is substituted with cheaper metals such as nickel, but the delithiated structure of LixNiO2 is not thermally stable in the presence of organic electrolyte. However, as a result of partial substitution of cobalt with nickel and manganese, LiNixCoyMn1-x-yO2 has high thermal stability and is widely investigated as positive electrode material for the Li-ion batteries.
The aim of this research was to understand how metal substitutions and particle morphology effect on the electrode cycle life in the Li-ion cell. Electrode materials LiCoO2 and LiNixCoyMn1-x-yO2 were prepared from a several of precursors under different synthesis conditions to achieve optimal crystal sizes and morphologies for Li-ion cell. Phase purities and crystal sizes were studied by XRD and morphologies of particles were investigated by FESEM from the electrode foil cross-sections. After electrochemical cycle tests, the morphologies of particles were re-investigated to see how the testing affect to the different morphologies and chemistries of samples.
Results indicate that crystal size and morphology has big influence on the electrochemical cycling properties of LiNixCoyMn1-x-yO2 electrode material in the Li-ion cells. The optimum particle size and morphology were obtained from the experiments and discussed.
Electrochemical Properties of Lithiated Silicon/Sulfur Battery
Authors: Kim Hyung-Sun , Jeong Tae-Kyung 
Published: February 2020

The lithium sulfur battery has much higher specific capacity of 1675 mAh/g and energy density of 2600 Wh/kg than conventional lithium ion battery [1]. However, the lithium sulfur battery is difficult to commercialize because a lithium metal used as anode has dendrite growth and explosiveness. Traditional graphite anodes that are applicable for rechargeable Li-ion batteries may not be suitable for rechargeable sulfur batteries since they have low capacity and poor passivation in ethereal solutions. Therefore alternative anodes for sulfur cathode are required. Silicon anode material, which exhibits very high specific capacity of 4200 mAh/g (for a stoichiometry of Li4.4Si) is one of the most attractive candidates for Li-ion batteries [2, 3]. Combining pre-lithiated silicon anode with sulfur cathode may promote the commercialization. However, both sulfur cathode and silicon anode have drawbacks. The most serious drawback in sulfur cathode that the capacity is rapidly decreased with cycling, because the lithium polysulfide, an intermediate product in the sulfur redox reaction is readily dissolved out into the electrolyte during cycling. Silicon as an anode material is hampered by its large volume expansion (>300%), causing pulverization, loss of electrical contact and consequently early capacity fading. Therefore, various approaches to solve such problems have been suggested [4].
In this work, we suggest an advanced lithium metal free, pre-lithiated silicon-sulfur battery. In our previous research, carbon mesh was inserted between the sulfur cathode and the separator [5]. Sulfur cathode with carbon mesh was inhibited polysulfide dissolved in an electrolyte and was enhanced a utilization of sulfur. In the silicon anode, carbon coating on silicon surface has been conducted. Silicon properties such as electrical conductivity and Li-ion conductivity can be enhanced by carbon coating. Prior to use in the silicon/sulfur battery, the silicon was lithiated by direct contact with a lithium metal in a 1M LiTFSI solution with 1, 2-dimethoxyethane (DME) and 1, 3-dioxolane (DOL) at volume ratio of 1:1. The results show that lithiated silicon-sulfur battery exhibits increased capacity and good cyclability.
[1] Y. Yang, M. T. McDowell, A. Jackson, J. J. Cha, S. S. Hong and Y. Cui, Nano let., 10 (2010) 1486-1491.
[2] N. Liu, L. Hu, M. T. McDowell, A. Jackson and Y. Cui, Acs Nano, 5 (2011) 6487-6493
[3] I. Hong, B. Scrosati, F. Croce, Solid State Ionics, 232 (2013) 24-28
[4] M. Green, E. Fielder, B. Scrosati, M. Wachtler, J. S. Moreno, Electrochemical and Solid-State Letters, 6 (2003) A75-A79
[5] T. G. Jeong, Y. H. Moon, H. H. Chun, H. S. Kim, B. W. Cho and Y. T. Kim, Chem. Commun., 49 (2013) 11107-11109
High-Capacity Characteristics of Li-S Rechargeable Battery Using CNT Electrode
Authors: Tsukahara Naoki , Fukuda Yoshiaki , Nozue Tatsuhiro , Murakami Hirohiko 
Published: February 2020

Carbon nanotubes (CNTs) are good electronic conductors and have a high chemical stability. We have synthesized vertically aligned CNTs directly on nickel foils and applied them to a cathode of a lithium-sulfur (Li-S) rechargeable battery [1, 2]. The CNTs grown by our thermal CVD process have characteristically a spiral structure. CNT/S composite cathodes were fabricated by impregnating the CNT films with molten S. Figure 1 shows cycle performance and Columbic efficiency of the CNT/S composite cathode containing 8 mg cm-2 with S content of 86 wt% in a 2032 type cell. LiTFSI (0.86 M) dissolved in DME/DOL (9:1 vol %) with LiNO3 (3 wt%) additives was used as electrolyte. The high S loading cell retained a specific capacity of 1000 mAh g-1 even after 50 cycles. This good performance is considered to be attributed by the spiral CNT structure which can hold the electrolyte containing the dissolved polysulfides with a little loss.
Reference
[1] T. Nozue, presented at the 2012 MRS Spring Meeting, San Francisco, 2012 (unpublished)
[2] T. Nozue, presented at The 54th Battery Symposium, Osaka, 2013 (unpublished)
Hierarchical Nanostructured Carbon/Sulfur Hybrid Cathode for High-Performance Lithium-Sulfur Battery
Authors: Peng Hong-Jie , Huang Jia-Qi , Zhao Meng-Qiang , Zhang Qiang , Liu Xin-Yan , Wei Fei 
Published: February 2020

Among various energy storage/conversion systems, lithium-sulfur batteries are considered as one of the most promising candidate due to not only very high theoretical energy density of 2600 Wh kg-1 (based on lithium-sulfur redox couple) and wide operating temperature range benefiting from its unique multiple-electron-transfer chemistry, but also abundant reserves and environmental friendliness of sulfur. However, several intrinsic obstacles should be overcome for its applicably extension, including the ultra-low electrical conductivity of sulfur and its lithiated products, huge volumetric changes during charge and discharge, and the shuttling mechanism of soluble intermediate polysulfides.
Here, a hierarchical nanostructured carbon/sulfur hybrid in which the porous carbon was in situ integrated into graphene/single-walled carbon nanotube (SWCNT) hybrid matrix with small cyclo-S8 molecule clusters was fabricated as advanced cathode material for lithium-sulfur battery application. The sp2 graphene/SWCNT hybrid interlinked framework was served as robust conductive scaffold with good electrical conductivity and structure stability, while the micro-/mesoporous carbon accommodated sulfur and lithium polysulfides, provided accessibility for liquid electrolyte to active material, and suppress the shuttle behavior due to the spacial confinement. Therefore, such hierarchical all-carbon nanostructure hybridized with small cyclo-S8 molecule clusters obtained an excellent electrochemical performance including an ultrahigh specific capacity of 1121 mAh g-1 at 0.5 C, a favorable high-rate capability of 809 mAh g-1 at 10 C, a very low capacity decay of 0.12 % per cycle, and an impressive cycling stability of 877 mAh g-1 after 150 cycles at 1 C. As sulfur loading increasing from 50 wt % to 77 wt %, high capacities of 970, 914, and 613 mAh g-1 were still available at current densities of 0.5, 1, and 5 C respectively. Based on the total mass of packaged devices, gravimetric energy density of GSH@APC-S//Li cell was expected to be 400 Wh kg-1 at a power density of 10000 W kg-1, matching the level of engine driven systems.

Reference:

[1] HJ Peng, et al. Adv. Funct. Mater., 2014, DOI: 10.1002/adfm.201303296
Advanced Cathode, Electrolyte and Separator materials to Improve the Energy Density and Cycle Stability of Soft-Package Lithium-Sulfur Battery
Authors: Zhang Hongzhang , Zhang Huamin , Zhang Yining 
Published: February 2020

The lithium/sulfur battery has been attracting increasing attention due to their higher theoretical specific energy density (2,600 Wh kg−1), almost ten times greater than that of commercially used lithium ion batteries. However the practical energy density of the Li/S battery (soft package) is still too low (<450Wh/kg), accompanied other unsolved problems as poor cycle life, low safety as well as worse rate capability. In order to solve these problems, we need to develop better cathode materials, better electrolyte composition, better anode protect mechanism and ect.
In our lab, we mainly focus on the study of cathode materials (carbon/sulfur), cathode structure, electrolyte and separators, which combined together to improve the battery performance. For one thing, by improving the cathode (including the carbon surface area, C/S ratio, porous distribution), the energy density of the Li/S battery has been improved to 500 Wh/kg and 600 Wh/L (discharge to 1.5V) in our lab. For another thing, by improving the electrolyte and separator, the Li/S coin cell could cycle 100 cycles (0.1 C) with capacity retention of 70% (still over 800mAh/g (S)) with 3.0 mg/cm2(S) cathode.
In this presentation, the development of Li/S battery in the energy storage department of DICP will be introduced, including materials design (cathode, electrolyte, and separator), preparation and soft package design. Battery performance with different carbon materials combined with different electrolyte and separators series will be summarized and discussed in detail.
Electrochemical Reaction Mechanism of Li2S Active Material in All-Solid-State Lithium-Sulfur Batteries
Authors: Hayashi Akitoshi , Hakari Takashi , Nagao Motohiro , Tatsumisago Masahiro , Ichinose Takahiro , Ozaki Tomoatsu , Togawa Yoshihiko , Mori Shigeo 
Published: February 2020

Rechargeable lithium-ion batteries have been widely used in portable electronic devices such as cellular phones and personal computers. Increasingly they are also being scaled up for using large applications in electric vehicles and smart grids. However, due to limited capacity in both cathodes and anodes, the specific energy density of lithium-ion batteries needs to improve remarkably to meet the requirements for practical applications. Current cathode materials have an actual capacity less than half that of anode materials such as graphite and silicon. Therefore, high-capacity cathode materials are required to realize lithium-ion batteries with higher-energy densities. Lithium sulfide, Li2S, is a high-capacity positive electrode material with the theoretical capacity of 1168 mAh g-1. However, there are two major issues to be solved. One is that its low electronic conductivity restricts its actual capacity to much lower values than that theoretically predicted. The other is capacity fading which arises from high dissolution of lithium polysulfide into the liquid electrolyte during the electrochemical reaction of Li2S electrode. The use of inorganic solid electrolyte (SE) is expected to inhibit the polysulfides dissolution. We reported that a Li2S–Cu composite electrode prepared by mechanical milling retained the reversible capacity of 350 mA h g-1 for 20 cycles in all-solid-state cells using Li2S-P2S5 SEs [1]. Recently it is found that Li2S electrode prepared by milling with carbon materials exhibited excellent cycling stability with high capacity of 700 mAh g-1 in the all-solid-state cells [2]. However, the origin of excellent reversibility has not been understood. In this study, reversible structural and morphological changes at the nanoscale during the full-electrochemical cycles in all-solid-state lithium-sulfur batteries have been revealed by high-resolution TEM, electron diffraction, and energy-dispersed X-ray spectroscopy experiments. The smooth and adhesive interface among Li2S active material, Li2S-P2S5 electrolyte, and acetylene black in Li2S composite electrodes is realized at the nanoscale, which is fabricated by mechanical milling technique. Reversible variations during cycles between crystallization and amorphization of sulfur-based active nanoparticles are responsible for the feasibility of the high capacity and excellent cycling stability.
References
[1] A. Hayashi, R. Ohtsubo, T. Ohtomo, F. Mizuno, M. Tatsumisago, J. Power Sources, 183 (2008) 422.
[2] M. Nagao, A. Hayashi, M. Tatsumisago, J. Mater. Chem., 22 (2012) 10015.