Effects of TiO2 phase on the performance of Li4Ti5O12 anode for lithium-ion batteries

In recent reports, doping TiO2 phases into Li4Ti5O12 system is an effective approach to improve the electrochemical performance of Li-titanate batteries, and the explanations of this phenomenon are mainly focused on the functions of TiO2 phases at low current density. In this paper, through the ex-situ X-ray diffraction analysis, it is revealed that the crystal structure of rutile-TiO2 in Li4Ti5O12-TiO2 electrode is very different after cycles at high and low current density. Such results can beneficially help us have a fully understanding of Li-ion storage mechanism in multi-phase electrode. Moreover, three kinds of dual and ternary phase Li4Ti5O12-TiO2 composites with the same morphology of nanosheets are fabricated and their electrochemical performances are compared for the first time. These Li4Ti5O12-TiO2 composites exhibit excellent performance at high current density: Li4Ti5O12-rutile-anatase TiO2 electrode delivers a reversible capacity of about 125 mA h g(-1) with a total capacity decreasing less than 5% after 2000 cycles at 30 C. Li4Ti5O12-rutile TiO2 nanosheets electrode tested from 1 to 50 C with 100 cycles for each rate delivers a capacity of 108 mA h g(-1) at high rate of 50 C, which is 69.2% of the specific capacity at 1 C. (C) 2016 Elsevier B.V. All rights reserved.