New Insights into Electrochemical Lithiation/Delithiation Mechanism of α‑MoO₃ Nanobelt by in Situ Transmission Electron Microscopy

The α-MoO₃ 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-MoO₃ nanobelt anode inside a transmission electron microscope to observe in situ the mircostructure evolution during cycles. Upon first lithiation, the α-MoO₃ nanobelt converted into numerous Mo nanograins within the Li₂O matrix, with an obvious size expansion. Interestingly, α-MoO₃ nanobelt was found to undergo a two-stage delithiation process. Mo nanograins were first transformed into crystalline Li_1.66Mo_0.66O₂ along with the disappearance of Li₂O and size shrink, followed by the conversion to amorphous Li₂MoO₃. 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 Li₂MoO₃ was revealed accompanying the formation and disapperance of the Li₂O layer during the subsequent cycles. Our experiments provide direct evidence to deeply understand the distinctive electrochemical lithiation/delithiation behaviors of α-MoO₃ nanobelt, shedding light onto the development of α-MoO₃ 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_<i>x</i>P_<i>y</i> 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 Cu₂S Nanowire

Prediction from the dual-phase nature of superionic conductorsboth solid and liquid-like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 Cu₂S nanowires (NWs) using transmission electron microscopy (TEM). Specifically, we reveal the atomic scale details including phase transformation, migration and redox reactions of Cu⁺ 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 Cu₂S Nanowire

Prediction from the dual-phase nature of superionic conductorsboth solid and liquid-like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 Cu₂S nanowires (NWs) using transmission electron microscopy (TEM). Specifically, we reveal the atomic scale details including phase transformation, migration and redox reactions of Cu⁺ 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 Cu₂S Nanowire

Prediction from the dual-phase nature of superionic conductorsboth solid and liquid-like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 Cu₂S nanowires (NWs) using transmission electron microscopy (TEM). Specifically, we reveal the atomic scale details including phase transformation, migration and redox reactions of Cu⁺ 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