1,720,961 research outputs found
M-3(PO4)(2)-nanoparticle-coated LiCoO2 vs LiCo0.96M0.04O2 (M = Mg and Zn) on electrochemical and storage characteristics
No full textThe electrochemical cycling and storage characteristics of LiCo0.96 M0.04 O2 and M3 (PO4)2 nanoparticle-coated LiCoO2 cathode materials (M=Zn and Mg) were compared at room temperature and 90°C between 3 and 4.5 V. The doped cathodes showed degraded electrochemical performance at room temperature compared to the uncoated cathode. The first discharge capacities of the uncoated and the doped cathodes were 186 and 175 mAhg, respectively. The doped cathodes showed 30 mAhg after 30 cycles, while the uncoated cathode showed 100 mAhg after 50 cycles at a 1 C rate. Mg3 (PO4)2 and Zn3 (PO4)2 -coated LiCoO2 showed discharge capacities of 179 and 187 mAhg, respectively, and hadsignificantly improved capacity retention, showing 133 and 153 mAhg, respectively, after 50 cycles. After storage at 90°C, in the electrolytes using 4.5 V charged electrodes, the doped cathodes showed both greatly decreased side reactions with the electrolytes and formation of Co3 O4 and CoO phases from Li and Co dissolution. However, the coated cathodes did not show either structural transformation into the Co3 O4 and CoO phases or side reactions with the electrolytes.close7
Dependence of electrochemical Behavior on concentration and annealing temperature of LixCoPO4 phase-grown LiNi0.8Co0.16Al0.04O2 cathode materials
No full textLix CoPO4 phase-grown LiNi0.86 Co0.1 Al0.04 O2 cathode materials were prepared by varying the coating concentration of precipitated Co3 (PO4)2 nanoparticles and the annealing temperature. These materials were characterized by analyzing their electrochemical properties, moisture uptake, and thermal stability. Among the various coating concentrations, 3 wt % coating showed no decrease in the first discharge capacity (193 mAhg) and a much improved capacity retention (90%) at a 1 C cycling rate after 40 cycles, compared to the bare cathode (193 mAhg and 44% for first discharge capacity and capacity retention, respectively). Using this concentration, the annealing time was varied from 2 to 7 h at 700, 800, and 900°C. The coated cathode annealed at 700°C for 7 h showed comparable electrochemical properties and moisture uptake to that annealed at 700°C for 5 h. Even after annealing at 700°C for 7 h, P ions remained on the particle surface with a similar coating thickness to that at 700°C for 5 h. However, increasing the annealing temperature led to a further decrease in electrochemical properties and was related to deeper diffusion of P ions into the bulk particle, which likely formed a solid solution consisting of bulk elements and P elements. The amounts of Li2 CO3 and LiOH formation of the coated samples upon exposure to air with a relative humidity of 40% showed a similar result when annealing at 700°C, but increasing the annealing temperature to 800 and 900°C resulted in a significant increase of the amount of Li2 CO3 and LiOH. Thermal stability was also greatly improved by the coating, and the sample annealed at 700°C for 7 h exhibited a decreased total heat capacity (240 Jg) compared to the 5 h annealed samples (380 Jg) even though those values were much smaller than the bare sample (980 Jg).close8
Storage characteristics of LiNi0.8Co0.1+xMn0.1-xO2 (x=0, 0.03, and 0.06) cathode materials for lithium batteries
No full textLiNi0.8 Co0.1+x Mn0.1-x O2 cathodes with x=0, 0.03, and 0.06 were prepared by firing a mixture of stoichiometric amounts of LiOH H2 O and coprecipitated Ni0.8 Co0.1+x Mn0.1-x (OH) 2 powders at 800°C for 15 h. Using these powders, their storage characteristics upon exposure to air and electrolytes at 90°C were compared before charging and after charging to 4.3 V with a variation of the storage time. The discharge capacities of the LiNi0.8 Co0.1+x Mn0.1-x O2 cathodes with x=0, 0.03, and 0.06 were 192, 186, and 184 mAh/g, respectively, while their irreversible capacity ratios were 13, 12, and 8%, respectively. As the Co content (x) increased in the cathode, both the Ni2+ content in the lithium 3a sites, and the contents of the LiOH and Li2 CO3 impurity phases decreased. In particular, changes in the oxidation state of the Ni and Mn ions after 4.3 V charging upon storage at 90°C were monitored using X-ray absorption near-edge spectra, and Ni4+ was found to reduce to Ni3+ while the oxidation state of the predominant Mn4+ did not change. However, residual Mn3+ ions in the cathodes dissolved into the electrolytes. Moreover, the cathodes stored at 90°C for 7 days were transformed into a spinel phase (Fd3m), regardless of the Co content. In an effort to resolve this dissolution problem, Al2 O3 and Co3 (PO4) 2 nanoparticles were coated onto the cathode (LiNi0.8 Co0.1 Mn0.1 O2) with the highest amounts of metal dissolution at 90°C. The results showed that the Co3 (PO4) 2 -coated cathode exhibited a greatly decreased metal dissolution and decreased its irreversible capacity by 5%, compared with a bare and Al2 O3 -coated cathode.close343
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
