Polyaniline-coated sulfur/conductive-carbon-black (PANI@S/C) composites with different contents of sulfur are prepared via two facile processes including ball-milling and thermal treatment of the conductive carbon black and sublimed sulfur, followed by an in situ chemical oxidative polymerization of the aniline monomer in the presence of the S/C composite and ammonium persulfate. The microstructure and electrochemical performance of the asprepared composites are investigated systematically. It is demonstrated that the polyaniline, with a thickness of ≈ 5-10 nm, is coated uniformly onto the surface of the S/C composite forming a core/shell structure. The PANI@S/C composite with 43.7 wt% sulfur presents the optimum electrochemical performance, including a large reversible capacity, a good coulombic efficiency, and a high active-sulfur utilization. The formation of the unique core/ shell structure in the PANI@S/C composites is responsible for the improvement of the electrochemical performance. In particular, the high-rate charge/ discharge capability of the PANI@S/C composites is excellent due to a synergistic effect on the high electrical conductivity from both the conductive carbon black in the matrix and the PANI on the surface. Even at an ultrahigh rate (10C), a maximum discharge capacity of 635.5 mA h per g of sulfur is still retained for the PANI@S/C composite after activation, and the discharge capacity retention is over 60% after 200 cycles.

The titanium oxides with one-dimensional (1D) nanostructure are of significance in electrochemical lithium insertion owing to their high specific surface area and pore volume. In this study, nanorods with diameters of ca. 3−5 nm and lengths of 40−60 nm were prepared through the hydrothermal treatment of a hydrolysate obtained from TiCl4 with caustic soda as demonstrated by HRTEM. These nanorods are protonated titanate and can be converted into the anatase (TiO2) nanorods by a calcination at 400 °C. The anatase nanorods have a large specific surface area of 314 m2/g and a high pore volume of 1.514 cm3/g, respectively. The anatase TiO2 nanorods exhibit a large initial electrochemical lithium insertion capacity of 206 mAh/g and good reversibility. The splitting and multi peaks in cyclic voltammograms associated with differing site occupations are ascribed to the formation of the imperfection of the TiO2 nanorod lattice, which facilitates the transport of lithium in surface defects and bulk materials.

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