A Dendritic Nickel Cobalt Sulfide Nanostructure for Alkaline Battery Electrodes

A uniform dendritic NiCo₂S₄@NiCo₂S₄ hierarchical nanostructure of width ≈100 nm is successfully designed and synthesized. From kinetic analysis of the electrochemical reactions, those electrodes function in rechargeable alkaline batteries (RABs). The dendritic structure exhibited by the electrodes has a high discharge‐specific capacity of 4.43 mAh cm^?2 at a high current density of 240 mA cm^?2 with a good rate capability of 70.1% after increasing the current densities from 40 to 240 mA cm^?2. At low scan rate of 0.5 mV s^?1 in cyclic voltammetry test, the semidiffusion controlled electrochemical reaction contributes ≈92% of the total capacity, this value decreases to ≈43% at a high scan rate of 20 mV s^?1. These results enable a detailed analysis of the reaction mechanism for RABs and suggest design concepts for new electrode materials.     

Transparent,Anisotropic Biofilm with Aligned Bacterial Cellulose Nanofibers

Cellulose nanofibrils are attractive as building blocks for advanced photonic, optoelectronic, microfluidic, and bio‐based devices ranging from transistors and solar cells to fluidic and biocompatible injectable devices. For the first time, an ultrastrong and ultratough cellulose film, which is composed of densely packed bacterial cellulose (BC) nanofibrils with hierarchical fibril alignments, is successfully demonstrated. The molecular level alignment stems from the intrinsic parallel orientation of crystalline cellulose molecules produced by Acetobacter xylinum. These aligned long‐chain cellulose molecules form subfibrils with a diameter of 2–4 nm, which are further aligned to form nanofibril bundles. The BC film yields a record‐high tensile strength (≈1.0 GPa) and toughness (≈25 MJ m^?3). Being ultrastrong and ultratough, yet the BC film is also highly flexible and can be folded into desirable shapes. The BC film exhibits a controllable manner of alignment and is highly transparent with modulated optical properties, paving the way to enabling new functionalities in mechanical, electrical, fluidic, photonics, and biocompatible applications.     

Tungsten‐Based Materials for Lithium‐Ion Batteries

Lithium‐ion batteries are widely used as reliable electrochemical energy storage devices due to their high energy density and excellent cycling performance. The search for anode materials with excellent electrochemical performances remains critical to the further development of lithium‐ion batteries. Tungsten‐based materials are receiving considerable attention as promising anode materials for lithium‐ion batteries owing to their high intrinsic density and rich framework diversity. This review describes the advances of exploratory research on tungsten‐based materials (tungsten oxide, tungsten sulfide, tungsten diselenide, and their composites) in lithium‐ion batteries, including synthesis methods, microstructures, and electrochemical performance. Some personal prospects for the further development of this field are also proposed.     

Stable Cycling of Phosphorus Anode for Sodium‐Ion Batteries through Chemical Bonding with Sulfurized Polyacrylonitrile

Sodium‐ion batteries are attracting increasing interests as a promising alternative to lithium‐ion batteries due to the abundant resource and low cost of sodium. Despite phosphorus (P) has extremely high theoretical capacity of 2595 mAh g^?1, its wide application for sodium‐ion battery is highly hampered by its fast capacity fading and low Coulombic efficiency as a result of large volume change upon cycling. Herein, a robust phosphorus anode with long cycle life for sodium‐ion battery via hybridization with functional conductive polymer is presented. To this end, the polyacrylonitrile is first dehydrogenated by sulfur via a facile thermal treatment, forming a conductive main chain embedded with C–S–S moieties. This functional conductive polymer enables the formation of P? S bonds between phosphorus and functional conductive matrix, leading to a robust electrode that can accommodate the large volume change upon substantial volume change in cycling. Consequently, this hybrid anode delivers a high capacity of ≈1300 mAh g^?1 at a current density of 520 mA g^?1 with high Coulombic efficiency (>99%) and good cycling performance (91% capacity retention after 100 cycles).     

InP衬底上InAlAs异变缓冲层和高铟组分InGaAs的生长温度优化

利用气态源分子束外延技术在InP衬底上生长了包含InAlAs异变缓冲层的In0.83Ga0.17As外延层.使用不同生长温度方案生长的高铟InGaAs和InAlAs异变缓冲层的特性分别通过高分辨X射线衍射倒易空间图、原子力显微镜、光致发光和霍尔等测量手段进行了表征.结果表明, InAlAs异变缓冲层的生长温度越低, X射线衍射倒易空间图 (004) 反射面沿Qx方向的衍射峰半峰宽就越宽, 外延层和衬底之间的倾角就越大, 同时样品表面粗糙度越高.这意味着材料的缺陷增加, 弛豫不充分.对于生长在具有相同生长温度的InAlAs异变缓冲层上的In0.83Ga0.17As外延层, 采用较高的生长温度时, X射线衍射倒易空间图 (004) 反射面沿Qx方向的衍射峰半峰宽较小, 77K下有更强的光致发光, 但是表面粗糙度会有所增加.这说明生长温度提高后, 材料中的缺陷得到抑制.     

新型高压脉冲体声波延迟线的设计

该文通过对换能器和延迟介质的优化设计,实现了一种新型高压脉冲体声波延迟线的研制。相比传统的声波延迟线,设计的延迟线具有高脉冲耐压性能,耐压高达2 kV;同时,其延迟线插损小,输出功率较大（瞬态可达2 W）,可充当新型无源功率MOS管驱动器,无需额外能量供给。试验表明设计的延迟线在大电流放电干扰情况下具有高延迟稳定性。     

飞行器静电起电放电的研究进展

飞行器作为空天装备重要的载体,其表面结构和材料差异造成电势差时,易发生静电放电,严重威胁飞行器的运行安全.文章从飞行器表面静电起电研究动态、飞行器静电起电机理、飞行器静电起电测试方法等方面介绍了该领域国内外的研究动态,以及本团队在静电起电机理以及静电起电测试方法方面研究的主要成果.提出了飞行器摩擦起电和喷流起电的测试方法,获得了飞行器摩擦起电与温度、湿度、摩擦速度以及接触面积之间的关系,通过试验测得了飞行器喷流起电使得飞行器带负电的结论,并分析了当前研究存在的问题和重点研究方向,为飞行器静电防护设计和安全性评估提供参考.     

移动增值实时扣费业务的解决方案

通过理论与实例介绍如何针对移动预付费增值业务多样化、复杂化以及业务不断变更的需求。快速、灵活实现各种新增值业务的实时扣费，为广大移动预付费用户提供灵活费率资费的解决方案。