Na2 Ti3 O7 @N-Doped Carbon Hollow Spheres for Sodium-Ion Batteries with Excellent Rate Performance.

Uniform Na2 Ti3 O7 hollow spheres assembled from N-doped carbon-coated ultrathin nanosheets are synthesized. A unique multilayer structure of nanosheets is presumed to significantly reduce energy consumption during the diffusion process of sodium ions, while the carbon-coated structure can increase the overall conductivity. The as-prepared sample used as an anode in sodium-ion batteries exhibits the best rate performance ever reported for Na2 Ti3 O7 , delivering more than 60 mAh g-1 after 1000 continuous cycles at the high rate of 50 C, which was achieved due to its unique structure.