Carbon-coated anatase titania as a high rate anode for lithium batteries

Abstract

Anatase titania nanorodsinanowires, and TiO2(B) are synthesized via a hydrothermal reaction of commercial TiO2 (P-25) in strong alkaline environment. Surfaces of these products are modified by carbon to improve the electrical conductivity through carbonization of pitch as the carbon source at 700 degrees C for 2 h in an Ar atmosphere. Even after carbon coating, the resultants exhibit the same crystal structure and morphology as confirmed by Rietveld refinement of x-ray diffraction data and transmission electron microscopic observation that the images display thin carbon coating layers on the surfaces of anatase nanorods and nanowires. Although the bare and carbon-coated anatase TiO2 nanorods exhibit stable cycling performance, the high rate performance is highly dependent on the presence of carbon because of high electrical conductivity, similar to 10(-1) S cm(-1), enabling Li+ ion storage even at 30 degrees C (9.9 A g(-1)) approximately 100 mAh (g-TiO2)(-1) for the carbon-coated anatase TiO2 nanorods. Besides, the bare and carbon-coated anatase TiO2 nanowires show poor electrode performances due to their large particle size and high crystallinity causing Li+ insertion into the host structure difficult. It is believed that the conducting carbon coating layers greatly improves the electrochemical property through the improved electrical conductivity and shortened diffusion path. (C) 2015 Elsevier B.V. All rights reserved.