Hierarchical Ti-Nb oxide microspheres with synergic multiphase structure as ultra-long-life anode materials for lithium-ion batteries

Titanium/niobium oxides have drawn wide attention due to their attractive high lithium-intercalation voltage avoiding, the formation of solid electrochemical interface. However, their poor electronic conductivity hinders the commercial applications because of the low electrochemical kinetics in lithiating and de-lithiating process. In the study, new approach to improving the low conductivity of the conventional oxides in micrometers are tactically proposed via the synergic effect of highly mixed multiphase oxide nanocrystals. Ti-Nb oxide composite microspheres with hierarchical microstructure are fabricated successfully via a very facile method combined solvothermal process and calcination. Interconnected crystalline nanoparticles of TiO2, Nb2O5 and TiNb2O7 nanocrystals are involved in the obtained Ti-Nb oxides, demonstrating high structure stability during electrochemical reaction. Meanwhile, the ionic/electronic conductivity is remarkably enhanced by the defects of O2- vacancies and Ti3+/Nb4+ ions. The remained specific capacity of the multiphase Ti-Nb oxides is up to 185.3 mAh g(-1) at 5 C with very weak capacity fade of 5.3% after 1800 cycles, showing a very long cycling stability. (C) 2017 Elsevier B.V. All rights reserved.