1,720,986 research outputs found
Development of new generation lithium-ion batteries within the NEXTCELL project
No full textThe growing demands for cost-effectiveness, electric vehicle user-friendliness, and safety are driving the need for innovative advancements in Li-ion battery (LIB) material and cell design. The NEXTCELL project aims to address these challenges by introducing a new generation of LIB cells capable of high capacity and high voltage applications through the development and validation of a novel jellified cell concept. The project methodology focuses on prototyping, modeling, and evaluating technical, safety, sustainability, and cost enhancements.
The project involves collaboration among various partners specializing in different aspects related to battery production, characterization, and improvement. From industry leaders like FEV, SYENSQO, CRF (research center for the Fiat Chrysler Automobiles group), and ABEE (Avesta Battery & Energy Engineering), to research institutions like CIC ENERGIGUNE (Centro de Investigacion Cooperativa de Energias Alternativas Fundacion), POLITO (Politecnico di Torino), CEA (Commissariat A L’Energie Atomique et Aux Energies Alternatives), INEGI (Instituto De Ciencia e Inovacao em Engenharia Mecanica e Engenharia Industrial), and SIE (Sustainable Innovations Europe SL), each partner contributes expertise to different stages of the project.
Overall, NEXTCELL is committed to achieving fast and successful commercialization of the novel cell design, focusing on developing jellified cell materials and components to meet specific goals such as:
• Developing gel separators and electrolytes capable of operating up to 5 V vs Li+/Li, exhibiting an ionic conductivity comparable to that of a traditional porous separator soaked in a liquid electrolyte (> 1 mS/cm at RT).
• Designing gel composite LNMO (LiNi0.5Mn1.5O4) cathodes, that allow the operation at voltages up to 5 V vs Li+/Li and whose manufacturing process should not involve solvent usage.
• Creating gel silicon-carbon composite anodes with an initial reversible capacity of 90%, akin to graphite, but with a capacity of 1000 mAh/g.
• Implementing conductive carbon materials, particularly carbon nanotubes, known for their superior efficiency compared to traditional carbon conductors, to facilitate electrodes with enhanced electronic conductivity
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
Unveiling commercial carbon electrodes for potassium batteries: an in-depth characterization
No full textPotassium-ion batteries (PIBs) are witnessing during the last years an unprecedent interest from the research community. This trend is given by PIBs potential in replacing Li-ion batteries for stationary energy storage plants. Indeed, potassium is abundant on Earth (2.09 wt%), evenly distributed and characterized by a very low standard equilibrium potential (-2.93 V vs. SHE with respect to -3.09 V vs. SHE of Li+/Li) and Lewis acidity (smaller solvated ions and thus faster conduction).
Nevertheless, potassium provides ions the radius of which almost doubles the lithium one, i.e. 1.38 Å vs. 0.76 Å, respectively. This divergence requires a different kind of anode with respect to Li-ion batteries and, thus, a new approach in understanding their electrochemical storage performance is essential. Indeed, the confined space of a graphitic layered anode is not suitable for the accommodation of bigger K-ions as for the smaller Li-ions. The mechanical stress caused by the K-ions diffusion leads to the pulverization of graphitic materials and this shouts the need for anodes with disordered amorphous phases. Their high densitiy of voids and defects provides a high surface area, where K-ions can deposit and be adsorbed storing energy. For this reason, soft and hard amorphous carbon represent the most performing anode materials for PIBs, showing better life cycle, stability and capacity provided. Anyway, their storage mechanism is very different with respect to their Li-graphite system counterpart, where most of the electrochemical capacity is ascribed to the ion intercalation between the graphene layers, and only a limited amount is due to ion adsorption on graphite edges. Electrochemical storage on amorphous carbons occurs mainly as a Faradaic accumulation of ions on the carbon surface. The process is battery-like, nonetheless they behave as a capacitor, and so they are called pseudocapacitive materials.
In this work, commercial carbon materials, known as Super P, C65 and C45, and their pseudocapacitive behaviour are in-depth characterized through electrochemical and morphological analysis. Indeed, depending on their graphitization degree, cyclic voltammetry curve and voltage vs. specific capacity profiles can identify the voltage windows for both insertion and adsorption processes. These results can be confirmed by differential capacity curves, above all if extracted from increasing current data. The Cottrell statement relates the current response with the voltage scan rate and, from this relationship, Dunn’s method, Trasatti’s method, b-value measurement and diffusion coefficient spectra allow to identify and quantify the amount of pseudocapacitive behaviour of the material. To conclude, in-depth characterization allows us to better classify the electrochemical behaviour of these electrode materials, that is of vital significance when choosing the proper anode material for potassium-based batteries
Facing the bigger K-Ion challenge in potassium organic batteries
No full textOur world is grappling with an energy transition vital for planet survival. To achieve the transition, energy storage is essential. For this reason, Li-ion batteries (LIBs) have reached unprecedent attention from the research community and the global market. Nonetheless, lithium scarcity prevents LIBs from covering the entire demand of storage at global scale. As a result, potassium-ion batteries (PIBs) are strongly emerging as a viable technology for stationary storage and large-scale production for its features: K is 900 time more abundant than Li on the Earth crust, and thus much cheaper; among the alkali metals has the redox potential (-2.93 V vs. SHE) closest to Li one, the smallest Stokes radius, and can work with aluminium current collector at every voltage. Nonetheless, desolvated K-ions show the biggest radius, arising some challenges: once intercalated in the rigid inorganic electrode material structure, K-ions may cause the structure distortion, resulting in drastic capacity decay. As a matter of fact, commercially available graphite, which is the most used anode for alkali-ion batteries, as well as, Prussian blue and its analogs, which are up to now the best option as cathode material in PIBs, have finite interlayer and interstitial volume, respectively, which are too small to reversibly host K-ions.
From this starting point, our group has focused on possible solutions to address these issues in both anode and cathode, keeping always into account the imperative of lower impact PIBs production since they are meant for the large-scale. The high electronic conductivity and low redox potential of carbonaceous materials, which make them be the best choice as anodes, can be still exploited in PIBs if the limited interlayer volume is overcame. Here we report a highly porous carbon material, with X-Ray diffraction evidences of no stacking of graphene layers, successfully adopted as anode material. Its disordered structure allows the K-ion to insert without causing any damage to the carbon structure, but instead, upon cycling, they may cause its rearrangement to a structure perfectly suitable for K-ion hosting. This behavior is electrochemically translated in an increase of capacity for the first cycles and null decay of capacity, the values of which are comparable to commercial carbon blacks. Finally, the preparation has been designed to be as green as possible: pre-carbonized Kraft lignin is mixed with a potassium carbonate and urea, and then activated in tubular furnace at 700 °C under nitrogen flow.
On the cathode site, in potassium battery field very few satisfying options have been published to now, due to the challenging bigger K-ions. Organic electrodes are not-critical raw materials-based, cheap, environmentally friendly, tunable, and - above all – their intrinsic mechanical flexibility can lead to the reversible and damage-free accommodation of large sized K-ions, resulting in stable PIB performance. Their biggest drawback is the high solubility in organic solvents. In consideration of this, stable aminoxyl radicals like TEMPO have been investigated to exploit its tunability both as monomeric unit and polymeric materials, in pristine for and also functionalized in order to reduce its solubility in organic electrolytes. In our work, we also considered the effect of the amount of free radicals on the electrochemical properties, as well as the possibility to integrate the redox activity of an n-type material in a TEMPO-like-based electrode on an aluminum current collector
Variations 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
A Multipotent Precursor Approach for the Preparation of High-Molecular Weight Conjugated Polymers with Redox Active Units
Full text linkConjugated polymers have long been recognized as key materials in organic electronics, yet, in many instances, their processability remains challenging due to their inherent poor solubility and limited polymerization degrees, which limit the scope of several materials in device fabrication. In this study, a multipotent precursor strategy is introduced that enables the synthesis of high-molecular-weight conjugated materials incorporating either anthracene or anthraquinone units from a single precursor. These latter, based on 9,10-dihydroanthracene units, can be polymerized to high polymerization degrees and possess high solubility and processability, thanks to the flexibility of the main chain and the presence of sacrificial side chains. Different post-polymerization transformations allow the selective generation of conjugated polymers, preserving the polymerization degree and generating, from an identical precursor, different conjugated polymers characterized by a different chemical nature and different electronic characteristics. Remarkably, these transformations can also be performed on the precursors in the solid state without affecting drastically their morphology. Finally, the potential of this methodology is demonstrated in the fabrication of organic field-effect transistors and organic cathodes for potassium-ion batteries
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