Carbon coated ultrasmall anatase TiO2 nanocrystal anchored on N,S-RGO as high-performance anode for sodium ion batteries

Abstract

Anatase TiO2 has been investigated as one of the most promising anode materials for sodium ion batteries (SIBs) with low cost and high theoretical capacity. Herein, a composite material of TiO2/N,S-RGO@C with carbon coated ultrasmall anatase TiO2 anchored on nitrogen and sulfur co-doped RGO matrix was successfully prepared by a rational designed process. The composite structure exhibited ultrasmall crystal size, rich porous structure, homogeneous heteroatoms doping and thin carbon coating, which synergistically resulted in elevated electron and ion transfer. The anode exhibited high rate capacities with good reversibility under high rate cycling. The carbon coating was investigated to be effective to prevent active material falling and lead to long term cycling performance with a high capacity retention of 181 mAh g−1 after 2000 cycles at 2 C. Kinetic studies were carried out and the results revealed that the superior performance of the composite material were derived from the decreased charge transfer resistance and elevated ion diffusion. Results suggested that the TiO2/N,S-RGO@C composite is a promising anode material for sodium ion batteries. Keywords: Titanium dioxide, Nitrogen/sulfur doping RGO, Sodium ion battery, Long cycle life