Nanocrystalline TiO₂(B) as Anode Material for Sodium-Ion Batteries

High surface area, nanostructured, and phase-pure TiO 2 (B) noodles-like secondary particles were successfully synthesized by a facile one-pot synthesis, based on the hydrolysis of TiCl 3 using a mixture of ethylene glycol and water at moderate temperature. The primary nanoparticles have a uniform size and are about 15 nm in diameter as determined by TEM analysis and exhibit an increased exposure of the (010) facet as indicated by XRD analysis. Unlike the electrochemical reaction with lithium, the application as sodium-ion electrode material reveals substantial differences, including the initial amorphization of the TiO 2 (B) particles, accompanied by a partial irreversibility of the sodium storage, presumably related to sodium trapping inside the active material particles and the absence of a stable solid electrolyte interphase, as indicated by galvanostatic cycling and electrochemical impedance spectroscopy, respectively. Besides, TiO 2 (B)-based electrodes show a stabilized reversible capacity of about 100 mAh g −1 and a very good C rate capability.