Flexible Conductive Anodes Based on 3D Hierarchical Sn/NS-CNFs@rGO Network for Sodium-Ion Batteries

Metallic Sn has provoked tremendous progress as an anode material for sodium-ion batteries(SIBs).However,Sn anodes suffer from a dramatic capacity fading,owing to pulverization induced by drastic volume expansion during cycling.Herein,a flexible three-dimensional(3D)hierarchical conductive network electrode is designed by constructing Sn quantum dots(QDs)encapsulated in one-dimensional N,S codoped carbon nanofibers(NS-CNFs)sheathed within two-dimensional(2D)reduced graphene oxide(rGO)scrolls.In this ingenious strategy,1D NS-CNFs are regarded as building blocks to prevent the aggregation and pulverization of Sn QDs during sodiation/desodiation,2D rGO acts as electrical roads and“bridges”among NS-CNFs to improve the conductivity of the electrode and enlarge the contact area with electrolyte.Because of the unique structural merits,the flexible 3D hierarchical conductive network was directly used as binder-and current collectorfree anode for SIBs,exhibiting ultra-long cycling life(373 mAh g?1 after 5000 cycles at 1 A g?1),and excellent high-rate capability(189 mAh g?1 at 10 A g?1).This work provides a facile and efficient engineering method to construct 3D hierarchical conductive electrodes for other flexible energy storage devices.

High-performance enhancement-mode thin-film transistors based on Mg-doped In2O3 nanofiber networks

Although In2O3 nanofibers （NFs） are well-known candidates as active materials for next-generation, low-cost electronics, these NF based devices still suffer from high leakage current, insufficient on-off current ratios （Ion/Ioff）, and large, negative threshold voltages （VTH）, leading to poor device performance, parasitic energy consumption, and rather complicated circuit design. Here, instead of the conventional surface modification of In2O3 NFs, we present a one-step electrospinning process （i.e., without hot-press） to obtain controllable Mg-doped In2O3 NF networks to achieve high-performance enhancement-mode thin-film transistors （TFTs）. By simply adjusting the Mg doping concentration, the device performance can be manipulated precisely. For the optimal doping concentration of 2 mol%, the devices exhibit a small VTH （3.2 V）, high saturation current （1.1 × 10^-4 A）, large on/off current ratio （〉 10^8）, and respectable peak carrier mobility （2.04 cm2/（V.s））, corresponding to one of the best device performances among all 1D metal-oxide NFs based devices reported so far. When high-K HfOx thin films are employed as the gate dielectric, their electron mobility and VTH can be further improved to 5.30 cm^2/（V.s） and 0.9 V, respectivel）, which demonstrates the promising prospect of these Mg-doped In2O3 NF networks for high- performance, large-scale, and low-power electronics.