Effects of calcination parameters on the purity, morphology, and electrochemical properties of the synthesized TiNb2O7 by the solvothermal method as anode materials for Li-ion batteries

Abstract

This study aims to investigate the effects of calcination parameters including temperature (700, 800, and 900 °C) and holding time (5 and 10 h) on the purity, morphology, and Li-ion storage performance of the TiNb2O7 synthesized by the solvothermal method. The X-ray diffraction (XRD) results showed that the application of calcination treatment at 700 and 800 °C for 5 h in the air atmosphere resulted in the formation of the dual-phase product of TiNb2O7-Nb2O5 while the pure TiNb2O7 was obtained only by increasing the calcination temperature to 900 °C. The morphological analyses showed the formation of the TiNb2O7 porous microspheres with a diameter of 500 nm constructed by nanoparticles. On the other hand, results indicated that increasing the holding time from 5 to 10 h at a constant calcination temperature of 900 °C resulted in the occurrence of morphological evolution from porous microspheres to faceted irregular particles and particle growth. The electrochemical characterization of the pure samples showed that the TiNb2O7 porous microsphere had a very better electrochemical performance over the faceted sample in the cases of Li-ion storage capability, and rate capability while its cyclic stability was lower than faceted TiNb2O7.