6 research outputs found
New Insights into Electrochemical Lithiation/Delithiation Mechanism of α‑MoO<sub>3</sub> Nanobelt by in Situ Transmission Electron Microscopy
The α-MoO<sub>3</sub> nanobelt
has great potential for application as anode of lithium ion batteries
(LIBs) because of its high capacity and unique one-dimensional layer
structure. However, its fundmental electrochemical failure mechanism
during first lithiation/delithiation process is still unclear. Here,
we constructed an electrochemical setup within α-MoO<sub>3</sub> nanobelt anode inside a transmission electron microscope to observe
in situ the mircostructure evolution during cycles. Upon first lithiation,
the α-MoO<sub>3</sub> nanobelt converted into numerous Mo nanograins
within the Li<sub>2</sub>O matrix, with an obvious size expansion.
Interestingly, α-MoO<sub>3</sub> nanobelt was found to undergo
a two-stage delithiation process. Mo nanograins were first transformed
into crystalline Li<sub>1.66</sub>Mo<sub>0.66</sub>O<sub>2</sub> along
with the disappearance of Li<sub>2</sub>O and size shrink, followed
by the conversion to amorphous Li<sub>2</sub>MoO<sub>3</sub>. This
irreversible phase conversion should be responsible for the large
capacity loss in first cycle. In addition, a fully reversile phase
conversion between crystalline Mo and amorphous Li<sub>2</sub>MoO<sub>3</sub> was revealed accompanying the formation and disapperance
of the Li<sub>2</sub>O layer during the subsequent cycles. Our experiments
provide direct evidence to deeply understand the distinctive electrochemical
lithiation/delithiation behaviors of α-MoO<sub>3</sub> nanobelt,
shedding light onto the development of α-MoO<sub>3</sub> anode
for LIBs
Isobutylhydroxyamides from Sichuan Pepper and Their Protective Activity on PC12 Cells Damaged by Corticosterone
The pericarp of <i>Zanthoxylum
bungeanum</i> Maxim.,
commonly known as Sichuan pepper, is a widely used spice to remove
fishy odor and add palatable taste. A phytochemical investigation
of the 95% ethanol extract of Sichuan pepper resulted in the isolation
of 21 isobutylhydroxyamides, including 8 new ones named ZP-amides
G–N, among which the chiral resolution of racemic ZP-amide
A and ZP-amide B was successfully accomplished. The protective activity
on corticosterone-treated PC12 cells of the isolated isobutylhydroxyamides
was also evaluated. The new compounds <b>3</b>–<b>5</b> and the known compounds <b>1</b>, <b>1a</b>, <b>2</b>, <b>2a</b>, <b>11</b>, and <b>15</b> improved
the survival rate of PC12 cells. The bioactivity studies disclosed
the potential of Sichuan pepper to be developed as new neuroprotective
functional food
Visualizing the Electrochemical Lithiation/Delithiation Behaviors of Black Phosphorus by <i>in Situ</i> Transmission Electron Microscopy
Black phosphorus (BP) has drawn growing
attention as the anode
material for lithium-ion batteries (LIBs) because of its high theoretical
lithium storage capacity. However, its electrochemical processes and
fundamental failure mechanisms have not been completely understood
due to the lack of direct evidence. Here, we report the direct visualization
of the electrochemical lithiation/delithiation behavior of the BP
anode in nano-LIBs using the <i>in situ</i> transmission
electron microscopy technique. Upon lithiation, the BP anode is found
to undergo obvious anisotropic size expansion and phase change from
orthorhombic BP to amorphous Li<sub><i>x</i></sub>P<sub><i>y</i></sub> compounds. Unexpectedly, the BP anode pulverizes
suddenly during discharging, resulting in irreversibility of the lithiated
product and thus poor electrochemical cycling performance. This finding
discloses that the failure mechanism of the BP anode is mainly correlated
with the delithiation process rather than the lithiation one, which
subverts the commonly accepted understanding. The new mechanism insights
would serve to provide viable solutions for eliminating rapid capacity
fading that plagues the bulk BP LIBs
Spring-Like Pseudoelectroelasticity of Monocrystalline Cu<sub>2</sub>S Nanowire
Prediction
from the dual-phase nature of superionic conductorsî—¸both
solid and liquid-likeî—¸is that mobile ions in the material may
experience reversible extraction–reinsertion by an external
electric field. However, this type of pseudoelectroelasticity has
not been confirmed <i>in situ</i>, and no details on the
microscopic mechanism are known. Here, we <i>in situ</i> monitor the pseudoelectroelasticity of monocrystalline Cu<sub>2</sub>S nanowires (NWs) using transmission electron microscopy (TEM). Specifically,
we reveal the atomic scale details including phase transformation,
migration and redox reactions of Cu<sup>+</sup> ions, nucleation,
growth, as well as spontaneous shrinking of Cu protrusion. Caterpillar-diffusion-dominated
deformation is confirmed by the high-resolution transmission electron
microscopy (HRTEM) observation and <i>ab initio</i> calculation, which can be driven by either an external electric
field or chemical potential difference. The observed spring-like behavior
was creatively adopted for electric nanoactuators. Our findings are
crucial to elucidate the mechanism of pseudoelectroelasticity and
could potentially stimulate in-depth research into electrochemical
and nanoelectromechanical systems
Spring-Like Pseudoelectroelasticity of Monocrystalline Cu<sub>2</sub>S Nanowire
Prediction
from the dual-phase nature of superionic conductorsî—¸both
solid and liquid-likeî—¸is that mobile ions in the material may
experience reversible extraction–reinsertion by an external
electric field. However, this type of pseudoelectroelasticity has
not been confirmed <i>in situ</i>, and no details on the
microscopic mechanism are known. Here, we <i>in situ</i> monitor the pseudoelectroelasticity of monocrystalline Cu<sub>2</sub>S nanowires (NWs) using transmission electron microscopy (TEM). Specifically,
we reveal the atomic scale details including phase transformation,
migration and redox reactions of Cu<sup>+</sup> ions, nucleation,
growth, as well as spontaneous shrinking of Cu protrusion. Caterpillar-diffusion-dominated
deformation is confirmed by the high-resolution transmission electron
microscopy (HRTEM) observation and <i>ab initio</i> calculation, which can be driven by either an external electric
field or chemical potential difference. The observed spring-like behavior
was creatively adopted for electric nanoactuators. Our findings are
crucial to elucidate the mechanism of pseudoelectroelasticity and
could potentially stimulate in-depth research into electrochemical
and nanoelectromechanical systems
Spring-Like Pseudoelectroelasticity of Monocrystalline Cu<sub>2</sub>S Nanowire
Prediction
from the dual-phase nature of superionic conductorsî—¸both
solid and liquid-likeî—¸is that mobile ions in the material may
experience reversible extraction–reinsertion by an external
electric field. However, this type of pseudoelectroelasticity has
not been confirmed <i>in situ</i>, and no details on the
microscopic mechanism are known. Here, we <i>in situ</i> monitor the pseudoelectroelasticity of monocrystalline Cu<sub>2</sub>S nanowires (NWs) using transmission electron microscopy (TEM). Specifically,
we reveal the atomic scale details including phase transformation,
migration and redox reactions of Cu<sup>+</sup> ions, nucleation,
growth, as well as spontaneous shrinking of Cu protrusion. Caterpillar-diffusion-dominated
deformation is confirmed by the high-resolution transmission electron
microscopy (HRTEM) observation and <i>ab initio</i> calculation, which can be driven by either an external electric
field or chemical potential difference. The observed spring-like behavior
was creatively adopted for electric nanoactuators. Our findings are
crucial to elucidate the mechanism of pseudoelectroelasticity and
could potentially stimulate in-depth research into electrochemical
and nanoelectromechanical systems