Carbon-Coated Anatase TiO 2 Nanotubes for Li- and Na-Ion Anodes

Abstract

Carbon-coated, anatase titanium dioxide nanotubes were prepared bycarbonizing a polyacrylonitrile-based block copolymer grafted on theas-synthesized titanate nanotubes. As revealed by high resolutiontransmission electron microscopy (HRTEM) and electron energy lossspectroscopy (EELS), this approach results in a very homogeneous andthin carbon coating, which is advantageous for those active materialsstoring lithium without undergoing significant volume changes upon ion(de-)insertion. As a matter of fact, thus prepared carbon-coated TiO2nanotubes presented an excellent long-term cycling stability for morethan 500 cycles (0.02% capacity fading per cycle) and a very promisinghigh rate performance (about 130 and 110 mAh g(-1) at 10 C and 15 C,respectively). The influence of the tubular morphology on the rateperformance is briefly discussed by comparing carbon-coated nanotubesand nanorods. Finally, the carbon-coated nanotubes were alsoinvestigated as sodium-ion anode material, showing very promisingreversible capacities of around 170, 120, and 100 mAh g(-1) at C/10, 1C, and 2 C, respectively, rendering them as versatile anode material forlithium-and sodium-ion applications (C) The Author(s) 2014. Published byECS. All rights reserved.