分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Porous silicon/carbon (Si/C) structure has been proved of great help to enhance the electrochemical cycling performance of Si-based anode materials. Current fabrication of porous Si based anodes usually relies on the complicated chemical etching process with unavoidable pollution problem. Herein, a na- noporous Si/C composite was successfully fabricated by a facile spray drying and carbonization process. The environmentally benign NaCl is used as the sacrificing template for the generation of embedded nanopores, which can be easily removed by routine washing process. The as-prepared nanoporous Si/C anode exhibits a high reversible specific capacity of around 900 mAh g 1 with 78.2% capacity retention after 100 cycles. This synthetic method paves a simple and environment-friendly way to build porous Si based anode with improved electrochemical performance which is significantly important for the in- dustrial production.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Copper matrix composites reinforced with graphene nanoplatelets (GNPs) were prepared via molecular- level mixing process and spark plasma sintering process. The impacts of graphene content on micro- structure, mechanical performance, thermal diffusivity, electrical conductivity and tribological properties of the composites were investigated. For microstructure, GNPs distributed randomly in composites with low graphene concentration (no more than 0.8 vol.%), but aligned in the direction perpendicular to the consolidation force when graphene concentration was above 2.0 vol.%. The mechanical performance of copper was strengthened evidently by the graphene addition. However, the strengthen effects were firstly enhanced and then deteriorated by increasing graphene content. Thermal diffusivity showed a constant decrease with the increase of graphene content. Anisotropy thermal performance was obtained by composites with graphene alignment. Furthermore, graphene addition showed little negative impact on electrical conductivity but dramatically improved tribological performance.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Copper sulfide (CuS) nanorods with the size of sub-10 nm are synthesized via a facile solegel method without postethermal treatment. The as-prepared CuS nanorods are characterized by X-ray diffraction, transmission electron microscope, and energy dispersive X-ray spectroscopy as hexagonal covellite CuS. The as-prepared CuS nanorods utilized as anode material exhibit a high reversible capacity and excellent cycling stability up to 250 cycles, as well as high Coulombic efficiency. The unique structure of the CuS nanorods should be responsible for their excellent electrochemical performance.