Constructing Ti-O-C bond in Na0.23TiO2@N-doped carbon sphere using dihydroxybenzene as an anode material for sodium-ion batteries

Abstract

Na0.23TiO2 particles coated on a nitrogen-doped carbon sphere (NTO@NCS) were synthesized using dihydroxybenzene and hexamethylenetetramine as carbon and nitrogen sources, respectively. In the NTO@NCS-R sample, Na0.23TiO2 particles uniformly cover the surface of electrically conductive NCS by forming the Ti-O-C bonds between Na0·23TiO2 and NCS. The feature is favorable to provide the NTO electrode the structural robustness and sodium ion diffusion during cycling. The NTO@NCS-R electrode exhibits an outstanding discharge capacity of 193.1 mAh g−1 at 0.1 A g−1 after 300 cycles in the voltage range of 0.01–2.5 V, compared to bare Na0·23TiO2, NTO@NCS-C, and NTO@NCS-H. In addition, NTO@NCS-R exhibits a discharge capacity of 114.4 mAh g−1 at 1.0 A g−1 at 2000th cycle and 58.7 mAh g−1 at 2.0 A g−1 at 8000th cycle, respectively, proving fast sodium ion diffusion and excellent cycle stability during long-term cycles.