Facile Synthesis of SnNb2 O6 @C Composite with Ultrathin Carbon Layer as Anode Materials for High-Performance Sodium-Ion Batteries.

ABSTRACT

Niobium-based oxides have attracted a lot of attention as anode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacity, excellent rate capability and exceptional safety. However, their poor intrinsic electronic conductivity and sluggish sodium ions diffusion kinetics severely hinder their practical applicability. Here, SnNb2 O6 @C was successfully prepared by a simple solid-state reaction technique coupled with carbon coating. HRTEM images show that the SnNb2 O6 @C particles are covered with uniformly ultrathin amorphous carbon layer of about 1.8 nm, thus improving the electronic conductivity and diffusion coefficient of sodium ions. As anode for SIBs, the as-obtained SnNb2 O6 @C material exhibits excellent specific capacity (369 mAh g-1 at a current density of 50 mA g-1 ) and remarkable rate performance (177 mAh g-1 at 1000 mA g-1 ), which indicates its good prospect in practical application.