bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly Compressible and Conductive N-Doped Graphene Foam for Lithium Batteries
Authors: Moon In Kyu , Chun Kyoung-Yong , Oh Jungwoo 
Published: February 2020

Over almost five years, 3-dimensional graphene and graphene-based nanostructured foams have been widely progressed. These materials have potential for use in next-generation energy-related technology for energy storage and generation as well as use in sensors and actuators. Among graphene-based materials, graphene oxides (GOs) can be described as rising material candidates because they show multiple advantage of ultra-light, strong, flexible, elastic, and porous. In addition, they have excellent properties such as high surface area, robust mechanical strength, resistive chemical behavior, and scaffolds with high conducivity.
In this presentation, we describe the simple synthesis of ultralow-density 3-dimensional reduced graphene oxide (rGO) foams that show high electrical conductivity and excellent compressibility for the applicaion of lithium batteries. The rGO foams are synthesized using the combination of hydrothermal and thermal annealing method in which hexamethylenetetramine is employed. We confirm that the N-binding configurations of rGO foams increase as evidenced by the change in pyridinic-N/quaternary-N ratio. The conductivity of this graphene foam is almost 12 S/m at 0 strain, whereas the conductivity is ≈704 S/m at the compressive strain (≈80%), which is comparable to previous reported any 3D sponge-like low-density carbon materials. The foam also has excellent hydrophobicity (contact angle on water surface: ≈137°) and shows selective absorption for organic solvents and oils. The compressive modulus of the rGO foam is higher than that of other carbon-based foams. This graphene foam is the simplified, light-weight architecture allowing for large mass loading of guest materials. Our graphen foam has unique electrical and mechanical properties due to the presence of N-doped monolithic graphene, and can be suitable for the use in electrodes for lithium batteries, fuel cells, energy absorption, energy storage, and sensing applications.
* K.-Y. Chun & J. Oh are equally contributed as corresponding authors in this study .
Correlation of Structural Changes in Li Rich Cathode Materials to Their Electrochemical Performance
Authors: Aryal Shankar , Timofeeva Elena V. , Segre Carlo U 
Published: February 2020

Li rich oxides xLi2MnO3.(1-x)LiMO2, (M=Ni, Co, Fe, Al, Cr etc.) have attracted significant attention in recent years as the promising cathodes for Li-ion batteries because of their higher energy storage capacity, thermal stability, and lower costs. These materials are structurally integrated composites of two phases: monoclinic C2/m Li2MnO3 phase and trigonal R-3m LiMO2 phase [1]. The Li2MnO3 phase provides structural integrity to the LiMO2 during Li intercalation and also can be activated to LixMnOy at potentials higher than 4.5 V to further boost the energy storing capacity [2]. The reported performance of Li[Li1/6Fe1/6Ni1/3Mn1/2]O2 cathode is 282 mAh/g at first discharge [3], which is double the capacity of LiCoO2 cathode currently utilized in commercial Li ion batteries. However, before those cathodes could replace traditional materials two issues with Li-rich cathodes need to be resolved: gradual capacity loss (71% of capacity after 50 cycles [3]), and drop off in discharge voltage upon cycling (3.57 V of midpoint voltage at the 4th discharge decreases to 3.38 V at the 100thdischarge [4]). Both degradation phenomena are closely related to structural changes within the cathode materials during cycling.
To improve the performance of Li-rich cathode detailed understanding of the degradation mechanisms in those materials is required. In this talk we will report on the experimental study of evolution of structure as the function of cycle number, charge modes and composition in low cost, Li rich, Co free Li(Li0.2Nix/2Mn0.8-xFex/2)O2, 0.2<x<0.4 layered-layered oxide cathode. Our study employs x-ray diffraction for crystallographic phase analysis, scanning electron microscopy for particle size and morphology characterization, infrared spectroscopy for molecular bonding and in-situ x-ray absorption spectroscopy for probing the oxidation state and local structure within the materials, during charge and discharge cycles.
References:
1. Thackeray, Michael M., et al. "Li 2 MnO 3-stabilized LiMO 2 (M= Mn, Ni, Co) electrodes for lithium-ion batteries." Journal of Materials Chemistry17.30 (2007): 3112-3125.
2. Armstrong, A. Robert, et al. "Demonstrating oxygen loss and associated structural reorganization in the lithium battery cathode Li [Ni0. 2Li0. 2Mn0. 6] O2." Journal of the American Chemical Society128.26 (2006): 8694-8698.
3. Zhao, Taolin, et al. "Organic-acid-assisted fabrication of low-cost Li-rich cathode material (Li [Li1/6Fe1/6Ni1/6Mn1/2] O2) for lithium–ion battery." ACS applied materials & interfaces6.24 (2014): 22305-22315.
4. Zheng, Jianming, et al. "Corrosion/fragmentation of layered composite cathode and related capacity/voltage fading during cycling process." Nano letters 13.8 (2013): 3824-3830.
The Effect of Binders on the Performance of Silicon Oxide
Authors: Huang Haijun , Han Guangshuai , Xie Jingying , Zhang Quansheng 
Published: February 2020

The higher specific capacity and richness in natural resources makes SiOx-based become a research focus by international scholar in recent years. A lot volume changes of material in the process of cycling which affects the batteries’ cycling performance, thereby limiting its development and usage. While choosing suitable binder is critical to effectively enhance the performance of the silicon oxide (SiOx) that has high specific capacity and easy pulverization. Researched the lithium insertion/extraction properties of SiOx composite electrode which prepared with polyvinylidene fluoride (PVDF), LA132 (which major copolymerization chain is polyacrylonitrile-polyacrylic acid (PAN-PAA)), polyacrylic acid (PAA). Electrochemical cycling tests with a current density of 160mA/g shows that SiOx electrode with conventional binder PVDF results in rapid capacity loss, while aqueous binder LA132 and PAA could dramatically improve cycle performance of SiOx. SiOx with PAA electrode exhibits reversible capacity still up to 1090mAh/g after 50 cycles. The analysis and characterization methods of SEM, EIS, XRD and differential capacity plots, it is prove that amorphous or little crystalline binder have physical or chemical reaction with –OH of SiOx and formed class network constitute. The expansion pulverization of SiOx power limited in original domain and maintained electronic and ionic conductivity effectively, improved cycle performance of materials.

Acknowledgements

The project was supported by the Shanghai Science and Technology Development Fund (15DZ2282000).

References

[1] J. Li, L. Christensen, M. N. Obrovac, K. C. Hewitt and J. R. Dahn. J. Electrochem. Soc., 155(2008): A234-A238.
[2] N. S. Hochgatterer, M. R. Schweiger, S. Koller, P. R. Raimann, T. Wöhrle, C.Wurm and M. Winter. Electrochem. Solid-State Lett. 11(2008): A76-A80.
[3] X. J. Feng, J. Yang, X. L. Yu, Wang J L, Y. N. Nuli. J. Solid State Electrochem, 17(2013):2461-2469.
[4] I. Kovalenko, B. Zdyrko, A. Magasinski, B. Hertzberg, Z. Milicev, R. Burtovyy, I. Luzinov, G. Yushin. Scicence, 334(2011):76-79.

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Understanding the Effects of Cell Temperature Gradients on Battery Performance with Mathematical Modeling
Authors: Deshpande Rutooj , Shaffer Christian , Moore William 
Published: February 2020

With wide acceptance of lithium ion batteries for electric and hybrid vehicle applications, precise understanding of cell performance at different operating conditions is increasingly important. Cell temperature is often a critical variable determining the cell performance during the vehicle operation. For automotive applications, various cooling/heating strategies are used to keep the cell operating temperature within the predetermined limits. This ensures safety during cell operations as well as helps cells meet the cell warranty targets. Heat generation and heat rejection by a cell during the operation may result in non-uniform temperature distribution within a cell. These effects are pronounced in large format cells. The variation in local temperature affects the kinetic and transport rates and therefore, may result in non-uniformities in the current distribution across the length/breadth of the electrodes. Widely used, Pseudo 2D (P2D) porous electrode models may not be able to accurately predict cell performance with temperature distribution. Here a simple Pseudo 3D model is developed as an extension to the P2D model to understand the implications of the temperature gradient on the cell performance and eventually on the cell life. Differences in cell performance at uniform temperature operation and with cell temperature gradients are highlighted.
Modeling Intercalation Driven Volume Change in Porous Electrodes
Authors: Garrick Taylor R , Higa Kenneth , Srinivasan Venkat , Weidner John W. 
Published: February 2020

In order to accurately predict the behavior of electrochemical devices, it is necessary to develop sophisticated models that take into consideration transport processes, electrochemical phenomena, mechanical stresses, and structural deformations on the operation of an electrochemical system. Many different models exist that can predict the electrochemical performance of these devices under a variety of operating and design conditions. In many of these models, the porosity of a porous electrode is often assumed constant since the volume changes seen during the intercalation reaction can be small. However, electrode materials developed in recent years show significant volume changes during intercalation, which are unable to be accurately predicted using these constant porosity models.
Porosity and dimensional changes in an electrode can significantly affect the resistance of the battery during cycling and can cause premature failure of the battery due to generated stresses. Previously, we have shown the ability to incorporate dimensional and porosity changes in a porous electrode into a model to predict volume changes in the active material of a single electrode during intercalation through the coupling of porous rock mechanics and porous electrode theory. There were many assumptions used to obtain an analytical solution, including the assumption of bulk stress, bulk strain, uniform porosity, and uniform concentration across the electrode. Here, we present a model that removes these assumptions and illustrates the coupling of porous electrode theory and rock mechanics in order to predict stress, strain gradients, and porosity gradients across a porous electrode during cycling.
Mesoporous Nb2O5 Nanofibers with Pseudocapacitive Properties for Lithium and Sodium Storage
Authors: Wang Liu , Bi Xiaofang , Yang Shubin 
Published: February 2020

Mesoporous Nb2O5 nanofibers were scalable fabricated via a typical electrospinning method and a specific vapor hydrolysis, followed by an annealing treatment. The uniformly distributed mesopores of ~10 nm are generated through the controllable vapor-phase hydrolysis process without any addition of either hard template or surfactant, which is proved to be a contamination-free and environment-friendly method to obtain mesoporous Nb2O5. According to the merits of layered structure of orthorhombic Nb2O5 (T-Nb2O5) and large scale of mesopores for fast Li and Na ions transportation, the resulting Nb2O5 nanofibers exhibit outstanding electrochemical performance for both lithium and sodium storage, especially show an excellent capacitor-like high-rate performance. In order to explore the origin of these ultrafast charge storage properties, the charge storage kinetics was investigated by cyclic voltammetry. The analytic results reveal a surface-controlled kinetics, which is characteristic of capacitive behavior. Due to the pseudocapacitive charge storage properties, mesoporous Nb2O5 fibers display both high energy density and power density. The facile fabrication of high quality mesoporous Nb2O5 nanofibers and the demonstration of good pseudocapacitive behavior show the great potential of mesoporous Nb2O5 for applications in fast energy storage fields.
New Catalysts Prepared By Co-Sputter Deposition for Direct Oxidation of Methanol
Authors: Fang Dan , Narayanan S. R. 
Published: February 2020

Direct methanol fuel cells (DMFCs) are attractive because of the high energy density of methanol, the overall simplicity of the fuel cell system and the easy refueling.[1] The state-of-art DMFC systems are based on the use of platinum-ruthenium catalyst at the anode, platinum catalyst at the cathode, and a polymer electrolyte membrane separating the two electrodes.[2] Although fuel cell power source products are now available in the range of 50 Watt to 2 kW, the commercialization has not occurred in the anticipated large-scale mainly because of the high precious metal catalyst loadings and durability of ruthenium-based catalysts. Our present study is focused on the study of anode catalysts, specifically to improve durability and reduce its cost. To this end, we have examined binary catalysts consisting of platinum and a second metal M (M=niobium, tantalum and titanium) prepared by co-sputter-deposition.
Platinum and the metal M were co-sputtered from separate cathode targets simultaneously using a high-voltage direct current on a Toray paper substrate. The atomic composition of metal M to platinum was varied between 0.1-2 by fixing the sputtering power to the platinum target and varying the sputtering power to the target containing metal M. The structure, morphology and composition of the catalyst were investigated by SEM, EDX and XPS. The results of quasi-steady state voltammetry suggested that the well-known bi-functional mechanism for methanol oxidation was operative on Pt-Nb and Pt-Ta catalysts. With the same amount of platinum, the methanol oxidation current of Pt-Ta and Pt-Nb catalyst was significantly improved compared to a sputtered platinum catalyst (Figure 1). The methanol oxidation current of Pt-Ta and Pt-Nb catalyst was 11.1 times and 8.3 times of platinum catalyst at -0.1 V vs. mercury/mercury sulfate reference electrode. We will present our understanding of the interaction between Pt and M (M=Nb, Ta) in enhancing the electro-oxidation of methanol and report on our efforts towards optimization of the catalyst composition to lower the noble metal content and enable practical use of these new catalyst materials in fuel cells

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Over Lithiation Technique to Prevent Irreversible Lithium Loss Due to SEI Formation
Authors: Blaser Rachel , Karulkar Mohan 
Published: February 2020

High-capacity materials such as Si and C-Si composites are popular candidates for next generation anodes. However, these materials consume significant amounts of lithium during the formation of Solid Electrolyte Interface (SEI), leading to a large irreversible loss of lithium for cycling and loss of overall cell capacity. One approach to offsetting this effect is to overload the cathode to provide additional lithium. However, this approach reduces the overall cell energy density and reduces the benefits of using a higher capacity anode material. To enable better full cell implementation of Si based anodes, an additional source of sacrificial lithium for SEI formation would be desirable if it could be added to the cell without a significant weight penalty.
We have demonstrated the use of the dual cast technique to incorporate additional Li into the battery cell system using existing slurry casting procedures. The dual cast of NMC and Li2O2 has shown an increase in first cycle capacity up to 2.2x the capacity of traditional NMC cathodes under the same cycling conditions. Characteristic voltage profile curves were confirmed to be present only when Li2O2 was included in the cell. To achieve the full benefit of the additional lithium the voltage maximum must be increased to 4.6V during the initial break-in cycles. The capacity increase due to the Li2O2 was beyond the increase due to the overcharging that can occur when NMC is cycled beyond 4.3V to 4.6V. It was also shown that the dual cast electrodes with Li2O2 could tolerate being cycled in the presence of a carbonate solvent base electrolyte.

Figure 1
Electric and Hybrid-Electric Marine Ferries for Public Transportation Networks
Authors: Patey Timothy John 
Published: February 2020

Coastal cities and regions rely on marine vessels to ensure safe and timely transport of people within their public transportation networks. Local emissions of particulate matter and noise pollution are of increasing concern for growing cities. The UN forecasts the percentage of people living in cities will rise from 54 percent in 2014 to 66 percent in 2050 [1] when global population is forecast to reach 9.7 billion. Hence, the infrastructure built today will have to serve the growing communities of tomorrow.
Li-ion battery systems within electric and hybrid-electric marine vessels offer a low cost to greatly reduce local and global emissions of particulate matter and harmful gases within vessels which are traditionally powered by combustion of fossil fuels. In this work, design considerations of Li-ion batteries within marine vessels are presented, including cathode/anode requirements, safety, and thermal management considerations. Use of a thermal, electric, aging model is implemented for a first assessment of the dimensioning of a Li-ion battery system within a marine vessel, with a specific focus on the choice of lithium titanate as anode versus the conventional graphitic anode.
1. World Population Prospects, 2014, United Nations.

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(Invited) Actinide Endohedral Fullerenes: Uranium-Based Systems with Unique Bonding Motifs
Authors: Echegoyen Luis , Cai Wenting , Murillo Jesse , Chen Ning , Najera Daniel , Fortier Skie 
Published: February 2020

Endohedral fullerenes, which are carbon cages that encapsulate atoms, ions or clusters have been known since the early days immediately following the discovery of the fullerenes in 1985 by Smalley, Kroto and Curl. A wide range of cages, varying in size, shape and electronic properties have been observed which encapsulate individual atomic or ionic species or clusters that possess complementary characteristics. Of the many endohedral fullerenes that have been characterized and reported, lanthanide endofullerenes have received a lot of attention but the corresponding actinide systems have not been extensively investigated experimentally, although theoretical calculations have been reported, especially after the original report by Smalley et al in 1992 of the mass spectral observation of mono- and di-metallic Uranium endohedrals with formulas U@C2n (n=14-36) and U2@C2m (m=25-30). The latter species containing two U ions inside have been the subject of multiple theoretical calculations using multiple cages, mainly C60, C70, C80 and C90. However, experimental reports of these exotic compounds are limited to three and only one involved purification using a two-stage HPLC protocol and presented the UV-Vis spectra for U@C82 and U2@C80.
We have undertaken a systematic study of U endohedrals and have succeeded in identifying many different compounds using HRMS, and have succeeded in purifying and characterizing several mono-metallic endohedrals, including their x-ray single crystal structures, specifically U@C74 and two different isomers of U@C82.
Of particular interest for this presentation are totally unexpected Uranium endohedrals with formula U2C(2n+1), where n=39, 40 which correspond to carbides containing single C atoms encapsulated with two Us inside C78 and C80 cages. More interestingly, U2X@C2n compounds have also been detected, where X=N and O, besides C. These latter compounds will be described and their properties will be presented and discussed.
(Invited) Synthesis and Structural Elucidation of Y2C2@C2n (2n = 86, 88 and 90)
Authors: Pan Changwang , Lu Xing 
Published: February 2020

Carbide cluster metallofullerenes (CCMFs) have drawn more and more attention during recent years due to their special structures and properties1
-
3. Herein, we found that some unprecedented medium-sized carbon cages ranging from C86 to C90 can be stabilized by choosing suitable metal atoms (yttrium). Our single-crystal crystallographic results unambiguously showed that they are carbide cluster metallofullerenes Y2C2@C2n (2n=86,88 and 90). It is proposed that the size of the encapsulated metallic units plays a crucial role in stabilization of these medium-sized fullerene cages.

Reference

(1) Lu, X.; Akasaka, T.; Nagase, S. Carbide Cluster Metallofullerenes: Structure, Properties, and Possible Origin. Acc. Chem. Res.
2013, 47 (7), 1627–1635.
(2) Cai, W.; Bao, L.; Zhao, S.; Xie, Y.; Akasaka, T.; Lu, X. Anomalous Compression of D5(450)-C100 by Encapsulating La2C2 Cluster instead of La2. J. Am. Chem. Soc.
2015, 137 (32), 10292–10296.
(3) Cai, W.; Li, F.-F.; Bao, L.; Xie, Y.; Lu, X. Isolation and Crystallographic Characterization of La2C2@Cs(574)-C102 and La2C2@C2(816)-C104: Evidence for the Top-Down Formation Mechanism of Fullerenes. J. Am. Chem. Soc.
2016, 138 (20), 6670–6675.
(Invited) Recent Crystallographic Studies of Endohedral Fullerenes
Authors: Balch Alan L. , Olmstead Marilyn M. , Powers Xian B. , Bowles Faye L. 
Published: February 2020

Recent single crystal X-ray diffraction studies of endohedral fullerenes will be reported. These studies are aimed at identifying the particular shape of carbon cage and the positioning of the metal ions inside. A case of external modification of an endohedral fullerene will be described where the cage plays an unusual role in determining the reactivity of the external appendage.
(Invited) Extending the Spiral Algorithm to Non-Classical Isomers and Metallofullerenes
Authors: Gan Li-Hua , Fowler P.W. 
Published: February 2020

The face-spiral algorithm proposed by Manolopoulos et al.1 has been extensively used to construct classical fullerenes, 2 and the corresponding numbering of isomers has been recommended as a systematic nomenclature. The spiral algorithm is an important help in clarifying the structures of fullerenes, endohedral fullerenes and fullerene derivatives. Recent and accumulating evidence shows that non-classical fullerene cages with heptagon(s) or square(s) may be competitive with their classical counterparts in some situations; non-classical fullerene cages may be favored parent cages of metallofullerenes and fullerene derivatives. It is desirable to make a systematic examination of the effect of heptagon(s) and/or square(s) on the structures and properties of bare fullerenes, fullerene ions, metallofullerenes and fullerene derivatives. The original spiral algorithm does not generate non-classical fullerene isomers, but can be adapted to do so. An extended spiral algorithm can selectively generate non-classical fullerenes with one or two heptagon(s) or square(s) in the size range of interest, and has been used [3-5] to identify favored non-classical fullerenes and metallofullerenes. Energetic arguments suggest that non-classical fullerene cages may play a significant role in the formation of fullerenes and metallofullerenes.

References

[1] D. E. Manolopoulos, J.C. May, S.E. Down, Chem. Phys. Lett, 1991, 181, 105-111.
[2] P. W. Fowler, D. E. Manolopoulos, an Atlas of Fullerenes, Clarendon Press, 1995.
[3] L. H. Gan, D. Lei, P. W. Fowler, J. Comput. Chem. 2016, 37, 1907-1913
[4] L.-H. Gan, R. Wu, J.-L. Tian, J. Clarke, C. Gibson, P. W. Fowler, 2017, 38, 144–151
[5] L.-H. Gan, R. Wu, J.-L. Tian and P. W. Fowler, Phys. Chem. Chem. Phys., 2017, DOI: 10.1039/C6CP07370K.