Synthesis of a novel hexagonal porous TT-Nb2O5 via solid state reaction for high-performance lithium ion battery anodes

Hexagonal porous Nb2O5 was synthesized for the first time via a facile solid-state reaction. The structure and electrochemical properties have been optimized through tuning heating temperature. X-ray diffraction results indicate that pseudo hexagonal Nb2O5 (TT-Nb2O5) and orthorhombic Nb2O5 have been synthesized at different temperatures. Hexagonal sheet and porous structure of Nb2O5 were characterized by scanning electron microscopy and N2-adsorption-desorption isotherms. The as-prepared TT-Nb2O5 (heated at 600 °C) shows the best performance with a remarkable charge capacity of 178 mA·h/g at 0.2C, which is higher than that of T-Nb2O5. Even at 20C, TT-Nb2O5 offers unprecedented rate capability up to 86 mA·h/g. The high rate capacity is due to pseudocapacitive Li+ intercalation mechanism of TT-Nb2O5. The reported results demonstrate that Nb2O5 with good crystal structure and high specific surface area is a powerful composite design for high-rate and safe anode materials.