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Mesoporous silicon microspheres were fabricated via in situ magnesiothermic reduction of silicon oxide. Scanning and transmission electron microscopy images indicate that the diameter of the mesoporous silicon microspheres is approximately 500 nm. Mesopores with diameters ranging from 10 to 30 nm are homogeneously distributed in the silicon microspheres. The as-prepared mesoporous silicon microspheres show a reversible capacity of 3000 mAh g at 100 mA g discharge current density. After 60 cycles, the mesoporous silicon microspheres can still deliver a 1500 mAh g capacity at 1000 mA g discharge current density. The high reversible capacity, excellent cycling, and good rate capability of the fabricated material can be attributed to its mesoporous morphology and ultrafine particle size. [ABSTRACT FROM AUTHOR]

Graphene is an excellent substrate to load nanomaterials for energy applications due to its large surface area, excellent conductivity, mechanical strength, and chemical stability. In this study, thermal exfoliated functionalized graphene sheets with good conductivity and high BET surface area are anchored with mesoporous NiO nanoplates by in situ chemical synthesis approach. Electrochemical characterization shows that functionalized graphene sheets-NiO sample exhibits a high capacity of about 700 mAh/g at a discharge current density of 100 mA/g and a good cycling ability. The high capacity and good cycling ability of functionalized graphene sheets -NiO material were attributed to the intimate interaction between the graphene sheets and NiO nanoplates. The graphene sheets not only enhance the conductivity of NiO nanoplates but also improve the structure stability of NiO nanoplates. Furthermore, the mesoporous structure of NiO nanoplates is available to the transfer of electrolyte. Such functionalized graphene sheets-NiO nanocomposite could be a promising candidate material for a high-capacity, low cost, and nontoxic anode for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Graphene-SnS nanocomposites were prepared via a solvothermal method with different loading of SnS. The nanostructure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The XRD patterns revealed that hexagonal SnS was obtained. SEM and TEM results indicated that SnS particles distributed homogeneously on graphene sheets. The electrochemical properties of the samples as active anode materials for lithium-ion batteries were examined by constant current charge-discharge cycling. The composite with weight ratio between graphene and SnS of 1:4 had the highest rate capability among all the samples and its reversible capacity after 50 cycles was 351 mAh/g, which was much higher than that of the pure SnS (23 mAh/g). With graphene as conductive matrix, homogeneous distribution of SnS nanoparticles can be ensured and volume changes of the nanoparticles during the charge and discharge processes can be accomodated effectively, which results in good electrochemical performance of the composites. [ABSTRACT FROM AUTHOR]