Dual carbon coating engineering endows hollow structured TiO2 with superior sodium storage performance

Abstract Nanostructure designing has been showing great potential in improving the sodium storage performance of nanomaterials. As a promising sodium ion battery anode, the large-scale application of TiO2 are largely restricted by the sluggish Na+ diffusion and its low electronic conductivity. To solve those drawbacks, we design a unique dual carbon coated hollow sphere structured TiO2 (H–C@TiO2@C). In this unique structure, the outside and inner side dual carbon layers well confine the hollow structured TiO2 in the middle, which greatly improve the electronic conductivity of TiO2 and reduce its structure change during Na+ insertion/extraction process. In addition, the hollow sphere structure with high surface area endows sufficient soaking of the electrolyte, resulting in shortened ion diffusion path way and facilitated ion diffusion kinetics. Owing to those superiorities, the H–C@TiO2@C delivers a high reversible capacity of 335.4 mAh g−1 at 50 mA g−1, excellent rate capability and cycling stability when used as an anode in sodium ion battery. This work highlights that specific structure design combined with effective carbon coating is an effective strategy in improving the performance of energy storage materials.