Fermi Pressure and Coulomb Repulsion Driven Rapid Hot Plasma Expansion in a van der Waals Heterostructure.

Transition metal dichalcogenide heterostructures provide a versatile platform to explore electronic and excitonic phases. As the excitation density exceeds the critical Mott density, interlayer excitons are ionized into an electron-hole plasma phase. The transport of the highly non-equilibrium plasma is relevant for high-power optoelectronic devices but has not been carefully investigated previously.

Analysis of Twitter Activity and Engagement From Annual Meetings of the Society for Vascular Surgery and the Society of Interventional Radiology.

Background: Medical societies such as the Society for Vascular Surgery (SVS) and the Society of Interventional Radiology (SIR) have been encouraging the use of social media at annual meetings by establishing unique meeting hashtags (eg. #VAM19, #SIR19ATX). These two specialties have similar number of active physicians and share procedural interests.

Reconfigurable Dipole-Induced Resistive Switching of MoS Thin Layers on Nb:SrTiO.

The controllable band gap and charge-trapping capability of MoS render it suitable for use in the fabrication of various electrical devices with high- dielectric oxides. In this study, we investigated reconfigurable resistance states in a MoS/Nb:SrTiO heterostructure by using conductive atomic force microscopy. Low-resistance and high-resistance states were observed in all MoS because of barrier height modification resulting from redistribution of charge and oxygen vacancies in the vicinity of interfaces.

Energy-Density Improvement in Li-Ion Rechargeable Batteries Based on LiCoO + LiVO and Graphite + Li-Metal Hybrid Electrodes.

We developed a novel battery system consisting of a hybrid (LiCoO + LiVO) cathode in a cell with a hybrid (graphite + Li-metal) anode and compared it with currently used systems. The hybrid cathode was synthesized using various ratios of LiCoO:LiVO, where the 80:20 wt% ratio yielded the best electrochemical performance. The graphite and Li-metal hybrid anode, the composition of which was calculated based on the amount of non-lithiated cathode material (LiVO), was used to synthesize a full cell.

Electrochemical Behaviors of a Vapor-Phase Polymerized Conductive Polymer Coated on LiVO in Li-Metal Rechargeable Batteries.

A new coating method called vapor-phase polymerization (VPP) is used to coat a conductive polymer on LiVO (LVO) surfaces for the first time in lithium-metal secondary batteries to protect the interface layer and enhance the electrochemical properties of the cathode. The VPP method can be used to coat an appropriate amount of the polymer and homogeneously coat the LVO active material surfaces because of the use of vapor-phase monomers. The presence of the coating layer was confirmed by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy.

Quasi-Solid-State Rechargeable Li-O Batteries with High Safety and Long Cycle Life at Room Temperature.

As interest in electric vehicles and mass energy storage systems continues to grow, Li-O batteries are attracting much attention as a candidate for next-generation energy storage systems owing to their high energy density. However, safety problems related to the use of lithium metal anodes have hampered the commercialization of Li-O batteries. Herein, we introduced a quasi-solid polymer electrolyte with excellent electrochemical, chemical, and thermal stabilities into Li-O batteries.

Effect of Tungsten Nanolayer Coating on Si Electrode in Lithium-ion Battery.

Tungsten (W) was coated onto a silicon (Si) anode at the nanoscale via the physical vaporization deposition method (PVD) to enhance its electrochemical properties. The characteristics of the electrode were identified by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis, and electron probe X-ray microanalysis. With the electrochemical property analysis, the first charge capacities of the W-coated and uncoated electrode cells were 2558 mAh g and 1912 mAh g, respectively.

Virtual Out-of-Plane Piezoelectric Response in MoS Layers Controlled by Ferroelectric Polarization.

The MoS carrier distribution can be controlled with the use of a dielectric environment substrate. Ferroelectric thin films are used to investigate the electrical responses at the MoS layer. The MoS/(111)-PbTiO vertical heterostructure is investigated, and the electrical responses, including piezoelectricity, are obtained using piezoresponse force microscopy.

Electrochemical Behavior of Li-Cu Composite Powder Electrodes in Lithium Metal Secondary Batteries.

A new type of Li-Cu composite powder electrode (Li-Cu CE) was fabricated via mechanical blending of Li and Cu powders. The new Li-Cu electrode is capable of replacing Li metal anodes in Li metal secondary battery (LMSB) systems without exhibiting typical intrinsic problems such as dendrite growth, volume change, and electrolyte depletion. Thus, Li-Cu CE cells can offer longer lives and very high capacities.

Electrochemically Induced Shape-Memory Behavior of Si Nanopillar-Patterned Electrode for Li Ion Batteries.

A nanopillar-patterned Si substrate was fabricated by photolithography, and its potential as an anode material for Li ion secondary batteries was investigated. The Si nanopillar electrode showed a capacity of ∼3000 mAh g during 100 charging/discharging cycles, with 98.3% capacity retention, and it was revealed that the nanopillars underwent delithiation via a process similar to shape-memory behavior.

Dendrite Suppression by Synergistic Combination of Solid Polymer Electrolyte Crosslinked with Natural Terpenes and Lithium-Powder Anode for Lithium-Metal Batteries.

Lithium-metal anode has fundamental problems concerning formation and growth of lithium dendrites, which prevents practical applications of next generation of high-capacity lithium-metal batteries. The synergistic combination of solid polymer electrolyte (SPE) crosslinked with naturally occurring terpenes and lithium-powder anode is promising solution to resolve the dendrite issues by substituting conventional liquid electrolyte/separator and lithium-foil anode system. A series of SPEs based on polysiloxane crosslinked with natural terpenes are prepared by facile thiol-ene click reaction under mild condition and the structural effect of terpene crosslinkers on electrochemical properties is studied.

Flexible, Freestanding, and Binder-free SnO(x)-ZnO/Carbon Nanofiber Composites for Lithium Ion Battery Anodes.

Here, we demonstrate the production of electrospun SnO(x)-ZnO polyacrylonitrile (PAN) nanofibers (NFs) that are flexible, freestanding, and binder-free. This NF fabric is flexible and thus can be readily tailored into a coin for further cell fabrication. These properties allow volume expansion of the oxide materials and provide shortened diffusion pathways for Li ions than those achieved using the nanoparticle approach.

Solid Polymer Electrolytes Based on Functionalized Tannic Acids from Natural Resources for All-Solid-State Lithium-Ion Batteries.

Solid polymer electrolytes (SPEs) for all-solid-state lithium-ion batteries are prepared by simple one-pot polymerization induced by ultraviolet (UV) light using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as an ion-conducting monomeric unit and tannic acid (TA)-based crosslinking agent and plasticizer. The crosslinking agent and plasticizer based on natural resources are obtained from the reaction of TA with glycidyl methacrylate and glycidyl poly(ethylene glycol), respectively. Dimensionally stable free-standing SPE having a large ionic conductivity of 5.

Preventing the dissolution of lithium polysulfides in lithium-sulfur cells by using Nafion-coated cathodes.

The principal drawback of lithium-sulfur batteries is the dissolution of long-chain lithium polysulfides into the electrolyte, which limits cycling performance. To overcome this problem, we focused on the development of a novel cathode as well as anode material and designed Nafion-coated NiCrAl/S as a cathode and lithium powder as an anode. Nafion-coated NiCrAl/S cathode was synthesized using a two-step dip-coating technique.

Electrochemical properties of lithium powder anode cell with gel polymer electrolyte and lithium trivanadate cathode.

A Li secondary cell composed of a Li powder anode with a gel polymer electrolyte (GPE) and a lithium trivanadate cathode was assembled, and its morphology and electrochemical properties were investigated. The cell had an initial charge/discharge capacity of about 190 mA h g(-1) at 0.1 C-rate, with 70% capacity retention over more than 30 cycles.

Electrochemical analysis of the effect of Cr coating the LiV3O8 cathode in a lithium ion battery with a lithium powder anode.

Rechargeable 2032-coin-type cells were produced with Li-powder anodes (i.e., Li-powder electrodes, LPEs) and either Cr-coated lithium trivanadate (Li1+xV3O8, LVO) cathodes or uncoated LVO cathodes.