TiNb2O7/carbon nanotube composites as long cycle life anode for sodium-ion batteries

TiNb2O7/carbon nanotubes composite (TNO/CNTs) was successfully synthesized by ultrasonic dispersion and a facile solvothermal method. Its physical properties were investigated by X-ray diffraction (XRD), thermogravimetric analysis (TG), and scanning microscopy (SEM). As the anode material of sodium ion battery, its electrochemical performances including cyclic voltammograms (CVs), electrochemical impedance spectra (EIS), and galvanostatic charge-discharge cycles were detected and analyzed for the first time. Compared with pure TiNb2O7, a high-reversible capacity reaches 261.1mAhg(-1) at 50mAg(-1) after 200cycles. In addition, a prominent rate capability maintains 110mAh g(-1) at 500mAg(-1) with over 1000cycles. The improvements have been explained by the corresponding kinetics analysis which demonstrates that the pseudocapacitive behavior in TNO/CNTs contributes a lot to the enhanced sodium storage capacities and rate performance. The results show the great potential of TNO/CNTs composites for sodium-ion battery with a long cycle life.