Polymer-Promoted Synthesis of Porous TiO2 Nanofibers Decorated with N-Doped Carbon by Mechanical Stirring for High-Performance Li-Ion Storage.

Abstract

Extensive efforts have been devoted to developing simple, low-cost, and high-production-yield methods to prepare hybrid materials with desired structural features for high-performance lithium storage. Here, a novel strategy is reported for fabricating the porous TiO2 nanofibers decorated with N-doped carbon (TiO2/C nanofibers) by a combination of mechanical stirring and the addition of a polymer in a beaker at ambient temperature, followed by calcination. The mechanical stirring process can provide homogeneous mixing of reactants in a solution, whereas the polymer acts not only as a structure-directing agent for fabricating one-dimensional nanofibers but also as the carbon and nitrogen source to generate N-doped carbon framework and porous structures. The TiO2/C nanofibers have average diameters of 500 nm and lengths up to 65 μm and are further composed of intercrossed TiO2 nanocrystals with sizes of 8 nm, with micropores centered at 1.5 nm and mesopores at 3-6 nm. The TiO2/C electrodes demonstrated a high reversible capacity (368 mAh g-1 at 0.25C after 200 cycles), good cycling performance (176 mAh g-1 at 10C over 2000 cycles), and excellent rate capability (97 mAh g-1 at 20C).