1,721,092 research outputs found
N-Alkyl-N-ethylpyrrolidinium cation-based ionic liquid electrolytes for safer lithium battery systems
No full textThe performance of ionic liquid (IL) electrolytes based on N-alkyl-N-ethylpyrrolidinium cations combined with different lithium salts has been used for the design of safer lithium battery systems. These mixtures of ILs, synthesized through an eco-friendly procedure route, and salts were studied and their performance was compared on the basis of anion species. The N-butyl-N-ethylpyrrolidinium bis(fluorosulfonyl)imide/lithium bis(fluorosulfonyl)imide (PYR24FSI-LiFSI) mixture was found to exhibit superior characteristics in terms of ion transport properties even at low temperatures in combination with wide electrochemical stability, feasibility of reversibly plating lithium metal without any reduction of electrolyte and good compatibility with Li anode. These are considered to be due to good film-forming ability of the FSI anion. Conversely, lower thermal stability was also observed. Preliminary tests in lithium/lithium iron phosphate, Li/LiFePO4, half-cells using PYR24FSI-LiFSI as the electrolyte evidenced cycling performance approaching that in organic electrolytes with high capacity retention and efficiency values. © 2016 Elsevier Ltd
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Towards Li(Ni0.33Mn0.33Co0.33)O2/graphite batteries with ionic liquid-based electrolytes. I. Electrodes' behavior in lithium half-cells
No full textLithium cells based on NMC cathodes or graphite anodes and ionic liquid-based electrolyte mixtures are investigated. The electrode tapes, using water-soluble natural binders, as well as the ionic liquid materials, are prepared through eco-friendly routes involving H2O as the only processing solvent. The Li/NMC and Li/graphite half-cells are studied by cyclic voltammetry, impedance spectroscopy and galvanostatic cycling tests at different temperatures. The results herein reported, demonstrate the performance improvement in terms of cycling behavior and ageing resistance, granted by the ionic liquid mixtures with respect to the electrolytes reported in literature based on a single ionic liquid. © 2016 Elsevier B.V
Room temperature ionic liquid (RTIL)-based electrolyte cocktails for safe, high working potential Li-based polymer batteries
No full textIn this work, we report novel room temperature ionic liquid (RTIL)-based electrolytes to be used with high-energy cathode, lithium-rich nickel manganese cobalt oxide (Li[Li0.2Mn0.56Ni0.16Co0.08]O2, LiR-NMC) in Li-ion batteries. The physical and electrochemical characteristics of the newly developed materials are thoroughly detailed, also by means of post-cycling electrochemical impedance spectroscopy (EIS) analysis of the resulting lab-scale lithium cells upon long-term, constant-current cycling (>1200 cycles). In addition, an innovative polymer electrolyte is developed encompassing the best performing RTIL-based electrolyte mixture, which is investigated in terms of its physico-chemical features, ion transport and electrochemical behaviour by EIS, cyclic voltammetry and constant-current (galvanostatic) cycling. The polymer electrolyte is obtained via facile, rapid and easily up-scalable UV-induced free radical polymerization (UV curing) technique, being a low-cost and solvent-free approach compared to other existing film formation techniques. The versatile fabrication method along with the use of appropriate materials may turn high-voltage, solid state and ageing resistant batteries into industrial reality in the coming years, as underlined by the excellent electrochemical response of the lithium polymer cell. © 2018 Elsevier B.V
Innovative nanomaterials for fuel cells fed with biogas
No full textChallenges on sustainability promote research policy focused on renewable-energy technology development in order to enhance global energy security, local energy independence, environmental protection and economic growth. Biomass resources offer renewable energies that can play a key role in the current global strategies for reducing greenhouse gas emissions by partially replacing fossil fuels. The conversion of biomass chemical energy into electrical energy and cogenerated heat can be obtained by fuel cells. In particular, molten carbonate fuel cell (MCFC) is the most suitable device for bioenergy production because it can be fed directly with biogas, whose primary constituents all improve the performance of the cell. However hydrogen sulfide, which is the main biogas impurity, poisons the traditional nickel based anode, affecting the power and the endurance of the cell. In order to overcome this problem, an innovative anode material that resists against the sulfide corrosions has been developed. This material, made of a nanostructured and porous nickel support covered with a thin layer of ceria, exhibits high sulfur tolerance and recovering capability. © Società Italiana di Fisica
Analisi sperimentale dei fenomeni erosivi in corrispondenza delle pile dei ponti: influenza della scabrezza e della permeabilità dell'accumulo di materiale flottante
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Ionic liquid electrolytes for safer lithium batteries I. investigation around optimal formulation
No full textIn this paper we report on the investigation of ionic liquid-based electrolytes with enhanced characteristics. In particular, we have studied ternary mixtures based on the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt and two ionic liquids sharing the same cation (N-methyl-N-propyl pyrrolidinium, PYR13), but different anions, bis(trifluoromethanesulfonyl)imide (TFSI) and bis(fluorosulfonyl)imide (FSI). The LiTFSI-PYR13TFSI-PYR13FSI mixtures, found to be ionically dissociated, exhibit better ion transport properties (about 10-3 S cm-1 at -20°C) with respect to similar ionic liquid electrolytes till reported in literature. An electrochemical stability window of 5 V is observed in carbon working electrodes. Preliminary battery tests confirm the good performance of these ternary electrolytes with high-voltage NMC cathodes and graphite anodes. Ionic liquid electrolyte mixtures, PYR13TFSI, PYR13FSI. © The Author(s) 2016. Published by ECS
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