8 research outputs found
Monodisperse Antimony Nanocrystals for High-Rate Li-ion and Na-ion Battery Anodes: Nano versus Bulk
We report colloidal synthesis of
antimony (Sb) nanocrystals with
mean size tunable in the 10â20 nm range and with narrow size
distributions of 7â11%. In comparison to microcrystalline Sb,
10 and 20 nm Sb nanocrystals exhibit enhanced rate-capability and
higher cycling stability as anode materials in rechargeable Li-ion
and Na-ion batteries. All three particle sizes of Sb possess high
and similar Li-ion and Na-ion charge storage capacities of 580â640
mAh g<sup>â1</sup> at moderate charging/discharging current
densities of 0.5â1C (1C-rate is 660 mA g<sup>â1</sup>). At all C-rates (0.5â20C, e.g. current densities of 0.33â13.2
Ag<sup>1â</sup>), capacities of 20 nm Sb particles are systematically
better than for both 10 nm and bulk Sb. At 20C-rates, retention of
charge storage capacities by 10 and 20 nm Sb nanocrystals can reach
78â85% of the low-rate value, indicating that rate capability
of Sb nanostructures can be comparable to the best Li-ion intercalation
anodes and is so far unprecedented for Na-ion storage
Efficient and Inexpensive SodiumâMagnesium Hybrid Battery
We
present a hybrid intercalation battery based on a sodium/magnesium
(Na/Mg) dual salt electrolyte, metallic magnesium anode, and a cathode
based on FeS<sub>2</sub> nanocrystals (NCs). Compared to lithium or
sodium, metallic magnesium anode is safer due to dendrite-free electroplating
and offers extremely high volumetric (3833 mAh cm<sup>â3</sup>) and gravimetric capacities (2205 mAh g<sup>â1</sup>). Na-ion
cathodes, FeS<sub>2</sub> NCs in the present study, may serve as attractive
alternatives to Mg-ion cathodes due to the higher voltage of operation
and fast, highly reversible insertion of Na-ions. In this proof-of-concept
study, electrochemical cycling of the Na/Mg hybrid battery was characterized
by high rate capability, high Coulombic efficiency of 99.8%, and high
energy density. In particular, with an average discharge voltage of
âŒ1.1 V and a cathodic capacity of 189 mAh g<sup>â1</sup> at a current of 200 mA g<sup>â1</sup>, the presented Mg/FeS<sub>2</sub> hybrid battery delivers energy densities of up to 210 Wh
kg<sup>â1</sup>, comparable to commercial Li-ion batteries
and approximately twice as high as state-of-the-art Mg-ion batteries
based on Mo<sub>6</sub>S<sub>8</sub> cathodes. Further significant
gains in the energy density are expected from the development of Na/Mg
electrolytes with a broader electrochemical stability window. Fully
based on Earth-abundant elements, hybrid NaâMg batteries are
highly promising for large-scale stationary energy storage
Effects of heroin on brain perfusion in contrast to placebo.
<p>BA: Brodmann area; L: left; P: perfusion; R: right; WM: white matter;</p>*<p>: pâ€0.05;</p>***<p>: pâ€0.001.</p><p>Each coordinate triple is a peak area of contrast intensity in one of the two significant clusters and refers to a specific area defined in the atlas of Talairach & Tournoux (1988).</p
Regional perfusion values of significant clusters.
<p>ACC: Anterior cingulate cortex; CI: Confidence interval; MPFC: Medial prefrontal cortex.</p
Physiological parameters after heroin and placebo administration.
<p>BP: Blood pressure; **: p<0.01.</p
Psychological effects of heroin.
<p>HCQ: Heroin Craving Questionnaire; SaO<sub>2</sub>: Blood oxygen saturation; SD: Standard deviation; VAS: Visual Analogue Scale;</p>*<p>: p<0.05.</p
Monodisperse and Inorganically Capped Sn and Sn/SnO<sub>2</sub> Nanocrystals for High-Performance Li-Ion Battery Anodes
We report a facile synthesis of highly
monodisperse colloidal Sn
and Sn/SnO<sub>2</sub> nanocrystals with mean sizes tunable over the
range 9â23 nm and size distributions below 10%. For testing
the utility of Sn/SnO<sub>2</sub> nanocrystals as an active anode
material in Li-ion batteries, a simple ligand-exchange procedure using
inorganic capping ligands was applied to facilitate electronic connectivity
within the components of the nanocrystalline electrode. Electrochemical
measurements demonstrated that 10 nm Sn/SnO<sub>2</sub> nanocrystals
enable high Li insertion/removal cycling stability, in striking contrast
to commercial 100â150 nm powders of Sn and SnO<sub>2</sub>.
In particular, reversible Li-storage capacities above 700 mA h g<sup>â1</sup> were obtained after 100 cycles of deep charging (0.005â2
V) at a relatively high current of 1000 mA h g<sup>â1</sup>
Altered regional perfusion in heroin in comparison to placebo condition.
<p>A) Relative hypo- (blue) and hyperperfusion (red) in heroin condition projected on an inflated brain (threshold: p<0.05). Hyperperfusion was not significant. B) Significant hypoperfusion (blue) in heroin condition (threshold: p<0.01; FEW corrected p<0.05). The z coordinate shows the position of each slice in reference to the Talairach atlas (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071461#pone-0071461-t003" target="_blank">Table 3</a>). The medial prefrontal cortex, the anterior cingulate cortex, and the insular cortex are shown in different colors, in order to clarify the spatial relationship to the significant clusters.</p