Structural and Electrochemical Study of Vanadium-Doped TiO2 Ramsdellite with Superior Lithium Storage Properties for Lithium-Ion Batteries

摘要

Titanium-oxide-based materials are considered attractive and safe alternatives to carbonaceous anodes in Li-ion batteries. In particular, the ramsdellite form TiO2(R) is known for its superior lithium-storage ability as the bulk material when compared with other titanates. In this work, we prepared V-doped lithium titanate ramsdellites with the formula Li0.5Ti1-xVxO2 (0x0.5) by a conventional solid-state reaction. The lithium-free Ti1-xVxO2 compounds, in which the ramsdellite framework remains virtually unaltered, are easily obtained by a simple aqueous oxidation/ion-extraction process. Neutron powder diffraction is used to locate the Li channel site in Li0.5Ti1-xVxO2 compounds and to follow the lithium extraction by difference-Fourier maps. Previously delithiated Ti1-xVxO2 ramsdellites are able to insert up to 0.8 Li+ per transition-metal atom. The initial gravimetric capacities of 270mAhg(-1) with good cycle stability under constant current discharge conditions are among the highest reported for bulk TiO2-related intercalation compounds for the threshold of one e(-) per formula unit.