The study on structure and electrochemical sodiation of one-dimensional nanocrystalline TiO2@C nanofiber composites

Titanium dioxide (TiO2) is a prospective anode candidate for sodium-ion batteries, owing to the advantages of good chemical stability, elemental abundance and nontoxicity. In this work, TiO2 embedded in carbon nanofiber (TiO2@CNF) composites are prepared for high-performance sodium-ion batteries by electrospinning and subsequent heat treatment in N-2 at different temperatures. With increase in heat-treatment temperature, the diameter of nanofibers decreases and the crystal phase partially transforms from anatase to rutile. Among all composites, the TiO2@CNF composite treated at 550 degrees C has anatase structure and exhibits the highest initial reversible capacity (237.3 mAh g(-1)), largest initial coulombic efficiency (68.2%), and superior capacity retention (100.3%) over 100 cycles at 30 mA g(-1). Whereas, the TiO2@CNF composite treated at 650 degrees C is 28.23% rutile and 71.77% anatase, and shows the best rate capability of 159.1 mAh g(-1) even at current density of 800 mA g(-1). It is, therefore, demonstrated that TiO2@CNF composites prepared with appropriate conditions are superior anode material for sodium-ion batteries. (C) 2015 Elsevier Ltd. All rights reserved.