Microwave-assisted synthesis and electrochemical characterization of TiNb2O7 microspheres as anode materials for lithium-ion batteries

Abstract

TiNb2O7 microspheres are prepared via a microwave-assisted solvothermal method. The microwave irradiation lowers the compound formation temperature to 600°C, and highly crystalline TiNb2O7 powders are obtained upon calcination at 800°C. Morphological analysis of the sample shows uniformly distributed microspheres with a particle size of around 1 μm. The Li+-ion diffusion coefficient calculated from the electrochemical impedance result is around 1.21 × 10−13 cm2 s−1, which is 1.5 times higher than the sample obtained from the conventional solvothermal method. The TiNb2O7 sample derived from microwave yields a high discharge capacity of 299 mA h g−1 at 0.1 C, whereas the sample synthesized via the conventional solvothermal process yields only 278 mA h g−1 at 0.1 C. Excellent rate capabilities such as 220 mA h g−1 at 5 C and 180 mA h g−1 at 10 C are also observed for the microwave-assisted solvothermal sample. Moreover, the sample exhibits a large capacity retention of 95.5% after 100 discharge–charge cycles at 5 C. These results reveal the appropriateness of the microwave-assisted solvothermal process to prepare TiNb2O7 powders with superior properties for battery applications.