Elemental
Si has a high theoretical capacity and has attracted
attention as an anode material for high energy density lithium-ion
batteries. Rapid capacity fading is the main problem with Si-based
electrodes; this is mainly because of a massive volume change in Si
during lithiation–delithiation. Here, we report that combining
an ionic-liquid electrolyte with a charge capacity limit of 1000 mA
h g–1 significantly suppresses Si volume expansion,
improving the cycle life. Phosphorus-doping of Si also enhances the
suppression and increases the Li+ diffusion coefficient.
In contrast, the Si layer expands significantly in an organic electrolyte
even with the charge capacity limit and even in an ionic-liquid electrolyte
without the limit. We demonstrated that the homogeneously distributed
Si lithiation–delithiation, phase-transition control from the
Si to Li-rich Li–Si alloy phases, formation of a surface film
with structural and/or mechanical stability, and faster Li+ diffusion contribute to suppressing Si volume expansion.
Neutron elastic scattering was used to determine the structure of as-received and lithiated amorphous SiO which has been proposed as an anode material for lithium ion secondary batteries. Based on a comparison between the total radial distribution functions ͓RDF(r)͔ of SiO and SiO 2 , it was suggested that amorphous SiO is composed of a three-dimensional SiO 4 tetrahedral network similar to silica (SiO 2 ) glass and metallic silicon clusters, and that the latter were finely dispersed in the SiO 4 matrix. On the other hand, electrochemically lithiated SiO showed a typical lithium negative correlation together with the disappearance of the Si-Si correlation in the RDF(r) which indicated that lithium predominantly reacted with the metallic silicon to form Li-Si alloys.
As anode materials
of Li-ion and Na-ion batteries, the electrochemical
insertion/extraction reactions of Li and Na were investigated for
a rutile-type Nb-doped TiO2 synthesized by a sol–gel
method. We changed the particle and crystallite sizes of the Nb-doped
rutile TiO2 powders by annealing at various temperatures
between 100 and 1000 °C and prepared thick-film electrodes consisting
of the powders. The anode performances were remarkably improved not
only in the Li-ion battery but also in the Na-ion battery with a reduced
annealing temperature of 400 from 1000 °C. We revealed that the
Nb-doped TiO2 showing better high-rate performances exhibited
a larger ratio of crystallite size to particle size. The size-dependent
enhancement in the performance of rutile TiO2 was much
more drastic than that of anatase TiO2. These results suggest
that rutile’s potential diffusivity of Li and Na appeared more
obviously when increasing the ratio because its diffusion coefficient
is anisotropic and significantly high.
We
hydrothermally synthesized various-element-doped rutile TiO2 for Na-ion battery anodes. Sn- and In-doped TiO2 electrodes
showed poor performances. In contrast, Ta- and Nb-doped TiO2 electrodes exhibited larger discharge capacities, which is attributed
to an expanded diffusion path and improved electronic conductivity.
Among them, the Ta-doped one delivered excellent cycling performance
and better rate capability. A first-principles calculation revealed
that Ta doping reduced electron charge density in rutile’s
Na+-diffusion path because Ta5+ has larger effective
nuclear charge to attract strongly outermost electron. Therefore,
Na+ was not bound by electron to easily diffuse in TiO2 particle, which leading to the enhanced capacity.
Background
This phase 2b part of a randomized phase 2/3 study assessed the efficacy and safety of ensitrelvir for mild-to-moderate coronavirus disease 2019 (COVID-19) during the Omicron epidemic.
Methods
Patients were randomized (1:1:1) to orally receive ensitrelvir fumaric acid 125 mg (375 mg on day 1) or 250 mg (750 mg on day 1) or placebo once daily for 5 days. The co-primary endpoints were the change from baseline in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) titer on day 4 and time-weighted average change from baseline up to 120 hours in the total score of predefined 12 COVID-19 symptoms. Safety was assessed through adverse events.
Results
A total of 341 patients (ensitrelvir 125 mg group, 114; ensitrelvir 250 mg group, 116; and placebo group, 111; male, 53.5%–64.9%; mean age, 35.3–37.3 years) were included in the efficacy analyses. The change from baseline in the SARS-CoV-2 titer on day 4 was significantly greater with both ensitrelvir doses than with placebo (differences from placebo: -0.41 log10 50% tissue-culture infectious dose/mL, P < 0.0001 for both). The total score of the 12 COVID-19 symptoms did not show a significant difference between the ensitrelvir groups and placebo group. The time-weighted average change from baseline up to 120 hours was significantly greater with ensitrelvir versus placebo in several subtotal scores, including acute symptoms and respiratory symptoms. Most adverse events were mild in severity.
Conclusions
Ensitrelvir treatment demonstrated a favorable antiviral efficacy and potential clinical benefit with an acceptable safety profile.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.