Carbon-coated anatase TiO₂ nanotubes for liand na-ion anodes

Carbon-coated, anatase titanium dioxide nanotubes were prepared by carbonizing a polyacrylonitrile-based block copolymer grafted on the as-synthesized titanate nanotubes. As revealed by high resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS), this approach results in a very homogeneous and thin carbon coating, which is advantageous for those active materials storing lithium without undergoing significant volume changes upon ion (de-)insertion. As a matter of fact, thus prepared carbon-coated TiO₂ nanotubes presented an excellent long-term cycling stability for more than 500 cycles (0.02% capacity fading per cycle) and a very promising high rate performance (about 130 and 110 mAh g^-1 at 10 C and 15 C, respectively). The influence of the tubular morphology on the rate performance is briefly discussed by comparing carbon-coated nanotubes and nanorods.