Structural Study of Carbon-Coated TiO2 Anatase Nanoparticles as High-Performance Anode Materials for Na-Ion Batteries

In this work, we study the electronic and atomic structural modifications occurring in TiO2 anatase nanoparticles as anode materials in Naion batteries upon sodiation and desodiation. The structural investigation is performed over both long- and short-range order by combining a comprehensive extended X-ray absorption fine structure (EXAFS) characterization with X-ray diffraction (XRD). The evolution of the electronic structure upon cycling is qualitatively investigated by X-ray absorption near-edge structure (XANES) analysis. The goal of this work is to correlate the outstanding electrochemical performance of carbon-coated TiO2 anatase nanoparticles in sodium batteries with the electronic and structural modifications induced during the sodiation and desodiation processes upon cycling. This work also demonstrates for the first time a coherent explanation of the,structural changes observed, where an electrochemically induced short-range ordering is revealed upon cycling.