bluuebunny/crossref_metadata_2025_split huggingface dataset:
Viscoelasticity of Short Polymer Melts from Atomistic Simulations
Authors: David Alessio , De Nicola Antonio , Milano Giuseppe , Raos Guido 
Published: February 2020

Tube theories provide a well-established description of the dynamics and viscoelasticity of polymer melts. Their equations are quite general, but they contain system-specific parameters such as the monomer friction coefficient and the packing length. These depend on the chemical structure of the polymer and they are typically obtained by experiment. In the long term, it would be desirable to be obtain these by computational methods, for example in order to allow the “in silico” screening of new materials and the rational formulation of new polymer blends.
Despite much recent progress, atomistic Molecular Dynamics (MD) simulations cannot yet be applied to simulate directly the behavior of entangled polymers. This is mostly due to the disparity between the typical times scales of the simulations and the relaxation times of the systems (microseconds versus seconds, as a rough order of magnitude). Given these limitations, our aim is to explore the applicability of atomistic MD simulations to investigate relatively short polymer melts (below the entanglement length) and extract parameters which are relevant for the viscoelasticity of polymer melts. In principle, the linear response of these systems can be extracted from ordinary equilibrium MD simulations (see for example the Green-Kubo relationship, linking the viscosity to the time-integral of the stress autocorrelation function). In addition, different variants of the Non-Equilibrium Molecular Dynamics (NEMD) method can be used to impose a shear deformation and record the resulting stress, thus obtaining the viscosity from their ratio (including its non-Newtonian shear-dependence). Both classes of methods present advantages and potential pitfalls, and at this stage it is important to develop a feeling for them. In this communication will present a comparison of these methods, using polyethylene, polypropylene and poly(methylmetacrylate) as benchmark systems in order to highlight their relative strengths and weaknesses.
(Invited) Modeling Morphology Distribution in Injection Molded Polypropylene Parts
Authors: Pantani Roberto , Liparoti Sara , Speranza Vito , Titomanlio Giuseppe 
Published: February 2020

The UNISA code, a software for the simulation of injection molding developed at the University of Salerno, considers a series of specific models to consider several aspects of the mutual effect of flow and crystallinity: the effects of temperature, pressure and flow on relaxation times, the effect of crystallinity on viscosity, the effect of flow on nucleation density and spherulitic growth rate. Each of the effects mentioned above was experimentally analyzed and described by a model for the iPP grade considered in this work. The combination of all these specific models becomes a model for the morphology evolution during polymer processing.
In order to verify the accuracy of the predictions, a series of injection molding tests were obtained applying a system which allows to control the cavity surface temperatures. This technique allows to keep, for assigned time intervals, the cavity surface temperature at intermediate values between injection and cooling channels temperatures. A modulation of the level of the cavity surface temperature and of the time, it was kept active, allowed to control the final sample morphology all the way from the complexity of a standard injection molded part down to a completely (skin and shear layers free) spherulitic structure.
The fibrillar layer morphology was related to the achievement of critical values of both the molecular stretch and the mechanical work, the latter being performed after the achievement of the critical molecular stretch. The dependence of the morphological layers (skin, shear, spherulitic layers, the latter including the transition from the shear zone) thicknesses upon the heating conditions was satisfactorily described by the models adopted.
Deep Red Phosphors Based on 3d Transition Metals for Energy Conversion from UV to Visible Rays
Authors: Matsushima Yuta , Kobayashi Riho , Tamura Hideto , Kamada Yuki , Sato Kazuya , Sato Chika , Kakihana Masato 
Published: February 2020

Reflecting the recent increasing concern about an energy issue, solar cells have been developing for several decades. Silicon is the major solar cell material with the band gap energy of ~1.17 eV. The optical absorption band corresponds to ~1100 nm and the radiations with wavelengths shorter than it are absorbed to generate photovoltaic power. The spectral sensitivity characteristics do not match the solar spectrum and energy conversion of the UV and blue radiations to longer wavelength side will improve further the efficiency of the Si solar cells. This work presents deep-red phosphors based on lithium aluminates and related compounds using 3d transition metals as the luminescent center. Deep-red emission by 3d transition metal phosphors has been much attracted because it can be attained with quite few rare-earth phosphors.
LiAlO2 and LiAl5O8 were chosen for phosphor host materials, which were prepared through a solid state reaction method from lithium and aluminum sources of LiF and Al2O3. The luminescent center of Fe3+ or Mn4+ was added in a form of Fe(NO3)3·9H2O or MnO2. The mixed powder in a Pt crucible was heat treated in air at 800-1300 °C.
It was found that the lithium source LiF brought several unusual phases in the products. Metastable α-LiAlO2 appeared at 800 °C and below when a mixture of LiF and Al2O3 was treated with an excess a LiF condition of LiF/Al = 3. It was good contrast to the fact that the a-phase obscurely crystalizes at 500-700°C with the broad peaks when LiOH·H2O was used as a lithium source. α-LiAlO2 transformed to stable γ-LiAlO2 at 800 °C or above. On the other hand, a mixture at LiF : Al2O3 = 1 : 2 resulted in a novel host material with an unknown composition. Although the XRD pattern itself has been reported as JCPDS #38-610, the details of the crystal structure and the actual composition have never been disclosed. The composition estimated in this work with EDS and XPS was Al4LiF0.1O6.45. A disordered spinel structure was assigned for ALFO by Rietveld analysis.
The luminescent spectra are compared among α-LiAlO2:Fe3+, γ-LiAlO2:Fe3+ and ALFO:Fe3+ in Fig. 1, and between LiAl5O8:Mn4+ and ALFO:Mn4+ in Fig. 2. α-LiAlO2:Fe3+, γ-LiAlO2:Fe3+ and ALFO:Fe3+ showed rather broad PL with the peak tops between 650 and 800 nm. Their peak positions are slightly different to each other and the emission peak of ALFO:Fe3+ resides at the shortest wavelength side. The excitation bands are in the UV region and the maxima are around 250 nm. On the contrary, the Mn4+ luminescent center changes its properties depending on the host materials. Deep red emission at 661 nm was much enhanced in ALFO:Mn4+, whereas LiAl5O8:Mn4+ exhibited only faint PL.
Acknowledgement: This work was performed under the Cooperative Research Program of "Network Joint Research Center for Materials and Devices (20181151).

Figure 1
(Keynote) A New Era for Hydrocarbon, Solid Polymer Electrolyte Membranes
Authors: Holdcroft Steven 
Published: February 2020

Full scale commercialization of Proton Exchange Membrane Fuel Cells (PEMFCs) is imminent yet fundamental knowledge in specialized areas is still required in order to resolve persistent technical barriers associated with high materials costs and limited reliability, versatility, and performance.
Perfluorinated proton-exchange polymers form the basis of standard high-performance PEMFCs but difficult synthetic chemistry hampers further materials development. Hydrocarbon proton-exchange materials, on the other hand, are founded on well-established and versatile synthetic chemistry that allows for rapid materials development, and offer a less expensive alternative to perfluorinated polymers. In this presentation, the evolution and properties of unique proton-conducting polymers will be described.

References:

• “Structurally-Defined, Sulfo-Phenylated, Oligophenylenes and Polyphenylenes”, J. Am. Chem. Soc, 137 (2015) 12223-12226.
• “Alcohol-Soluble, Sulfonated Poly(arylene ether)s: Investigation of Hydrocarbon Ionomers for Proton Exchange Membrane Fuel Cell Catalyst Layers”, J. Electrochem. Soc., 162 (2015) F513-F518.

Acknowledgements: T.J.G. Skalski, M. Adamski, M. Killer, E. Schibli, A. Hohenadel, B. Britton, B. Frisken, T. J. Peckham
Electrodeposition of Zn-Terephthalate MOF Thin Films
Authors: Nakamura Tenshou , Ueda Shotaro , Uda Kyota , Tsuda Yuki , Hirai Yuji , Sun He , Yoshida Tsukasa 
Published: February 2020

Metal organic flamework (MOF) is a class of inorganic / organic compound whose crystalline structure is made by bridging inorganic ions with organic ligands. Due to its open porous structure, special functionalities are anticipated in applications such as sensors, catalysis and batteries. Variation of MOFs is almost unlimited, not only by choice of building blocks but also by change of composition and crystalline structure.
We have recently reported microwave assisted hydrothermal synthesis of MOFs with various layered structures, in which Zn2+ ions are bridged by terephthalic acid (TPA). These Zn-TPA MOFs exhibited proton-selective reversible redox reactions, suggesting their usefulness in membrane-free redox batteries.
On the other hand, we have established a method to electrochemically self-assemble ZnO / organic dye hybrid thin films. When there is a favorable chemistry between inorganic and organic constituents, their hybrid nanostructures are spontaneously formed during electrolysis. Self-assembly of Zn-TPA MOFs can therefore be expected by minor addition of TPA into the bath for cathodic electrodeposition of ZnO.
Potentiostatic electrolysis at -1.0 V (vs. Ag/AgCl) in O2-saturated aqueous electrolyte containing 5 mM ZnCl2 and TPA up to 500 μM resulted in gradual decrease of cathodic current of oxygen reduction current (Fig. 1). Strong passivation occurs when TPA > 75 μM to reduce the steady-state current down to ca. 0.1 mA cm-2, as compared to the O2 transport limit (ca. 1 mA cm-2 for Zn2+ + O2 + H2O + 2e- → ZnO + H2O2). Minor addition of TPA at 5 μM resulted in appearance of thin flake-like deposits together with tiny grains of ZnO, which then changes into entire coverage of the FTO-glass substrate with the flakes at 200 μM while ZnO grains disappear (Fig. 2). X-ray diffraction (XRD) patterns of the deposits revealed that the flakes are those of Zn-TPA layered MOF in a Zn3(OH)4(TPA)•6H2O composition.
The passivation is obviously caused by high electrochemical resistance of the electrodeposited MOF towards O2 reduction, making it difficult to obtain thick MOF films for battery applications. Exploring the conditions to promote continuous electrochemical growth of MOF is under way.

Figure 1
Novel Organic Electrode Materialsfor Innovative Thick Electrode Based Aqueous Batteries
Authors: Perticarari Sofia , Grange Elodie , Pellegrin Yann , Guyomard Dominique , Odobel Fabrice , Poizot Philippe , Gaubicher J 
Published: February 2020

Thanks to the use of abundant chemical elements, organic chemistry provides great opportunities for discovering innovative electrode materials, which could be prepared (i) from renewable resources (biomass) and (ii) via eco-efficient processes, making the concept of greener and sustainable batteries possible [1]. Two types of reaction mechanisms can be used: n-type involving charge transfer with cation release/uptake and p-type involving anion uptake/release [2-5].
We are putting a lot of efforts on greener and sustainable organic batteries. In this communication, we report on novel materials, their uncommon reaction mechanism, and the performance of full aqueous cells.
We focus on aqueous organic batteries as a new promising green technology, barely studied yet, for which negative electrodes are missing. We have designed and synthesized novel mixed p- and n-type “bi-block” oligomer negative electrodes with repeating units made of naphthalene diimide and bipyridinium units [6]. They demonstrate optimal potential, extremely fast kinetics and highly competitive capacity and cyclability in both neutral aqueous Na and Mg electrolytes, including ocean water. Based on these findings, full organic cells bearing millimeter thick electrodes were assembled and tested [7]. These findings make a big step forward the design of low-cost rocking-chair dual-ion aqueous batteries.

References

1) P. Poizot, F. Dolhem, Energy Environ. Sci. 4, 2003 (2011).
2) Z. Song and H. Zhou, Energy Environ. Sci. 6, 2280 (2013).
3) S. Gottis, A.-L. Barrès, F. Dolhem, P. Poizot, ACS Appl Mater Interfaces 6, 10870 (2014).
4) E. Deunf, P. Moreau, E. Quarez, D. Guyomard, F. Dolhem, P. Poizot, J. Mater. Chem. A, 4, 6131 (2016).
5) E. Deunf, P. Jimenez, D. Guyomard, F. Dolhem, P. Poizot, Electrochem. Comm., 72, 64 (2016).
6) S. Perticarari, Y. Sayed-Ahmad-Baraza, C. Ewels, P. Moreau, D. Guyomard, P. Poizot, F. Odobel, J. Gaubicher, Adv. Energy Mater., 8, 1701988 (2018).
7) S. Perticarari, E. Grange, T. Doizy, Y. Pellegrin, E. Quarez, K. Oyaizu, A. J. Fernandez, D. Guyomard, P. Poizot, F. Odobel and J. Gaubicher, Chem. Mat., in revision
A First-Principle Study Towards Understanding Surface Reactions in Li-I2 Batteries
Authors: Liu Zhixiao 
Published: February 2020

Large-scale stationary energy storage urgently demands to develop rechargeable batteries with low cost, high energy density, and enhanced cycling stability. Beyond conventional Li-ion batteries, secondary Li-I2 batteries based on the conversion reaction mechanism is considered as a promising next-generation energy storage device. However, Li-I2 batteries also suffer shuttle effect caused by the high solubility of iodine in the organic electrolyte.
A first-principles approach is employed to probe the effect of I2 molecules on corroding the metallic Li anode surface. It is found that the I2 molecule always tends to dissociate to two I atoms on the Li surface. Electrons in the metallic substrate spontaneously migrate to I atoms, resulting in the self-discharge. According to the ab-initio molecular dynamics simulation, the metallic Li surface can be oxidized to LiI species. LiI species cannot binding to the metallic substrate strongly and will be exfoliated easily, leading to the loss of active materials and irreversible capacity fade. According to the present simulation, LiNO3 additive can also prevent the Li surface from the iodization corrosion. The NO3
- group can completely dissociate and penetrate into the Li substrate, result in forming a protective ternary compound layer. This layer can provide a strong affinity to LiI species, leading to alleviating the loss of active materials. Beyond LiNO3 additive, using N-doped graphene is another strategy to improve the battery performance. The N dopant can provide a strong attraction to trap I2 molecules. In addition, the N heteroatom can shift the Fermi energy level above the pi-antibonding states, which can enhance the reduction and dissociation of the I2 molecule.
(Invited) Working Towards a Cost-effective Lithium-ion Battery Recycling Process
Authors: Polzin Bryant J. , Spangenberger Jeffrey , Gaines Linda 
Published: February 2020

Lithium-ion batteries in electric and hybrid-electric vehicles are just now starting to reach their end-of-life. There are several options to address these end-of-life batteries, landfilling or recycling. Recycling is a desirable option because of the benefits it can bring, including reductions in life-cycle costs, reduced energy usage, lower environmental impacts, and decreased dependence on scarce or imported materials. The options available now for recycling of lithium-ion batteries are not optimal, so research and development (R&D) is needed to make economic processes available for use by the time large volumes of batteries from electric vehicles and other uses go out of service. By then these battery materials could be 20 year-old formulations with little residual value from its structure or contained elements. In particular, cathode formulations are evolving towards varied morphologies, emphasizing formulations that contain reduced quantities of cobalt (the valuable element sought in most current recycling operations), reducing the incentive for recycling with standard pyrometallurgical or hydrometallurgical methods.
Several key questions must be addressed by R&D. Most of these focus on the cathode, which is the most valuable form of material that can be recovered. How can the cathode get separated from the other cell components? Can they be recovered? How can optimum cathode function get restored? Can we separate one cathode type from another? Can we modify the cathode composition or morphology to update it for reuse? This presentation will provide a summary of Argonne’s work to create a feasible battery recycling system.
Nanocomposites of Copper Sulphide and Graphene Oxide for High-Performance Supercapacitors
Authors: Singhal Rahul , Thorne David , Lemaire Peter , Martinez Xavier , Zequine Camila , Gupta Ram , Uhl David , Scanley Ellen , Broadbridge Christine 
Published: February 2020

Supercapacitors or electrochemical capacitors are receiving greater interest because of their high-power density, long life, low maintenance, and safer operation. The low energy density of such devices needs to improve. In this work, copper sulfide (CuS), a cheap and environment-friendly compound, is used along with graphene oxide (GO) to provide high energy and power densities. CuS nanoparticles and its nanocomposites with GO was synthesized using a facile method for supercapacitor applications. For the synthesis of CuS, an appropriate amount of copper acetate was dissolved in a water-butanol solution for 30 minutes followed by the addition of thiourea. The final solution was then transferred into Teflon-lined stainless-steel autoclave and heated at 180oC for 24 hours. The resulting participate of CuS was recovered using a centrifuge, washed with DI water, and dried in air for 24 hours. A similar procedure was followed for the synthesis of CuS-GO nanocomposite with the addition of appropriate amount of GO in the water-butanol solution prior to the addition of copper acetate and thiourea.
Phase purity of the synthesized materials was determined by using X-ray diffraction (XRD) studies. XRD patterns of CuS showed the peaks at 2θ angle of 10.38o, 28.42o, 28.88o, 32.48o, 33.18o, 46.54o, 48.28o, and 59.68o corresponding to (100), (101), (102), (006), (110), (108), (116) planes, respectively, which indicates the covellite CuS hexagonal structure [1,2]. There were no additional peaks found in the XRD pattern of CuS-GO composite, confirming the phase purity of the synthesized materials. TEM images revealed nano-scale morphology of the synthesized particles. The particle size of CuS and CuS/GO composite were found as 95.11 nm, and 64.70 nm, respectively.
All the electrochemical measurements were conducted in standard three-electrode configuration, using a platinum wire as a counter electrode and Hg/HgO as a reference electrode. CuS and its composite with graphene oxide on nickel foam were used as working electrodes. All the electrochemical measurements were performed in 3M KOH solution. Electrochemical properties of the synthesized samples were investigated using cyclic voltammetry and galvanostatic charge-discharge studies. The specific capacitance was calculated from cyclic voltammogram, obtained at various scan rate between 10 - 300 mV/s. The specific capacitance of CuS and CuS-GO nanocomposite was found to be 400 and 600 F/g, respectively at a scan rate of 10 mV/s. The detailed results on synthesis, physical, and electrochemical characterization will be presented.

References:

[1] W. Xu, Y. Liang, Y. Su, S. Zhu, Z. Cui, X. Yang, A. Inoue, Q. Wei, C. Liang¸ Electrochim. Acta 211 (2016) 891–899.
[2] C. J. Raj, B. C. Kim, W. J. Cho, W. G. Lee, Y. Seo, K. H. Yu, J. Alloys and Comp. 586 (2014) 191–196.

Figure 1
Exploration of New Electrolyte Additive for Solid Electrolyte Interphase (SEI) Modification
Authors: Li Jingnan , Wu Bingbin , Lochala Joshua Andrew , Xiao Jie 
Published: February 2020

Solid electrolyte interphase (SEI), which is generated from the decomposition of the electrolyte at low potentials, plays an important role in repeated reversible ion transport and thus dictates the cycle life of electrochemical cells. [1] A stable SEI layer effectively suppresses the continuous decomposition of the electrolyte and enhances the fast ion diffusion during cycling. [2] As a critical component of SEI, LiF could effectively inhibit electron tunneling and improve the quality of SEI formed on anode materials. A LiF-rich SEI layer is believed to improve the uniformity of the electrode surface morphology and reduce the uneven deposition of Li metal. [3] However, how to enrich the LiF component in SEI layers is challenging. In this work, a new electrolyte additive has been designed and synthesized to produce more inorganic LiF during SEI formation. The electrolyte additive has been applied to both Si and Li anodes to understand the SEI formation mechanism in the presence of the new additive.
References

Collins, J., Gourdin, G., Foster, M., & Qu, D. (2015). Carbon surface functionalities and SEI formation during Li intercalation. Carbon, 92, 193-244.

Zhang, S. S. (2006). A review on electrolyte additives for lithium-ion batteries. Journal of Power Sources, 162(2), 1379-1394.

Zhang, X. Q., Cheng, X. B., Chen, X., Yan, C., & Zhang, Q. (2017). Fluoroethylene carbonate additives to render uniform Li deposits in lithium metal batteries. Advanced Functional Materials, 27(10), 1605989.
Development of a New 3D Hybrid Nanostructured Carbon/MnO2 Framework By Automated Spray Coating and Electrodeposition As High Performance Electrode Material for Supercapacitor Applications
Authors: Pognon Grégory , Rogier Clemence , Galindo Christophe , Bondavalli Paolo , Aubert Pierre-Henri , Vancaeyzeele Cedric , Nguyen Tran Minh Giao 
Published: February 2020

Nano-engineering of electrode through a versatile spray coating and subsequent electrochemical controlled modifications with metal oxide have been explorated toward a specific design of electroactive material targeting an increase energy densities in supercapacitors while maintaining high power densities. Exploiting pseudocapacitance and nanostructuration by combining transition metal oxides and nanostructured carbon materials in one electrode is considered as one of the best ways to achieve these performances.
In this study, carbon nanotubes/graphene/manganese dioxide nanostructured films were designed as supercapacitors electrodes. MnO2 is a well-known pseudocapacitive material used to increase the energy density allowing quite good cyclability of thousand cycles. The selected carbon nanomaterials generate high conductivity and their association is an efficient way to insure large surface area to maintain a high power density. The challenge is to assemble these materials into a nanostructured electrode with controlled homogeneity, morphology, and composition. Our approach consists in synthesizing MnO2 by anodic electrodeposition directly onto the conductive nanostructured carbon framework. The association of carbon nanotubes and graphene in a specific multi-layered organization by spray aim at creating a porosity controlled network in the electrodes with highly accessible and electroactive surface.
The carbon nanomaterials were deposited onto a current collector by dynamic automated spray gun deposition, an easily scalable, reproducible and industrially suitable method used for nanostructuration of thin films. Materials were characterized by SEM, XPS, microporosity analysis; their electrochemical behavior has been evaluated by cyclic voltammetry and impedance spectroscopy and their performances and cyclability by galvanostatic charge/discharge experiments. Results demonstrate that the capacitance can reach up to 190 F/g (110 F/cm3) for binder free electrodes thanks to a control of the MnO2 morphology, particle size and mass loading.