N-doped carbon coated anatase TiO₂ nanoparticles as superior Na-ion battery anodes

N-doped carbon coated TiO₂ nanoparticles (TiO₂@NC) were synthesized through a simple two-step route, in which dopamine was simultaneously utilized as both nitrogen and carbon sources. With TiO₂@NC applied in the Na-ion battery (SIB) anodes, the continuous and uniform N-doped carbon layer can not only enhance the electrical conductivity of TiO₂ and facilitate the surface pseudocapacitive process, but also serve as a buffer layer to accommodate the volume expansion during the sodiation-desodiation processes. The as-prepared TiO₂@NC exhibits excellent electrochemical performance when utilized as the SIB anodes, which delivers a remarkably high reversible capacity of 250.2 mAh g^-1 at a rate of 0.25C (84 mA g^-1) after 200 cycles and still retains 122.1 mAh g^-1 at 10C (3.35 A g^-1) even after 3000 cycles accompanied with a 95.3% retention of the maximum capacity, outperforming most of the reported TiO₂/C-based composites as SIB anodes. To our best knowledge, the preparation of TiO₂@NC with dopamine as both nitrogen and carbon sources and its application in the SIB anodes are reported for the first time.