Nitrogen and Sulfur Dual‐Doped Oxygen‐Deficient TiO2/C Composites for Superior Sodium Storage Properties

Abstract

AbstractSodium‐ion batteries (SIBs) have been considered as promising replacements to lithium‐ion batteries (LIBs) for large‐scale energy storage applications. For anode materials, titanium dioxide (TiO2) as a typical insertion‐type anode material have been extensively investigated as a safety, stable, cheap and environmental‐friendly anode materials for SIBs. Constructing suitable TiO2 crystal structure is a common modification strategy for improving the diffusion kinetics of sodium ion within TiO2 and its intrinsic electronic conductivity. Herein, a multi‐atomic doped oxygen‐deficient TiO2/C composites (N, S‐NTC) was successfully synthesized with excellent electrochemical performance. Synergistic effect of N, S and Ni elements on the structure, morphology and electrochemical performance was investigated. Electron Paramagnetic Resonance (EPR) spectroscopy, Raman spectroscopy and X‐ray photoelectron spectroscopy (XPS) analysis indicated that the Ni, N, S doping can introduce oxygen deficiency, narrow the bandgap of TiO2 and facilitating Na+ diffusion, further providing higher electronic/ionic conductivities and faster electron transport channel. As a consequence, the anode materials delivered ultrahigh rate performance and cycling performance of a high reversible capacity of 128.6 mA h g−1 at 1 A g−1 after 3000th cycles.