Zn2+ doped TiO2/C with enhanced sodium-ion storage properties

To improve the performance of anatase TiO2 as an anode material for sodium-ion batteries, Zn2+-doped TiO2/C composites are synthesized by a co-precipitation method. The results of XRD, EPR and XPS demonstrate that Zn2+ occupies at the Ti4+ site of TiO2 to form a solid-solution, resulting in an expansion of lattice and an increase of Ti3+ content. The expansion of lattice can enhance the stability of the crystal structure of TiO2. The increase of Ti3+ content can improve the conductivity of TiO2. Therefore, Ti0.94Zn0.06O2/C delivers a reversible capacity of 160 mA h g−1 with a capacity retention of 96% after 100 cycles at 5 C. Even charged/discharged at 10 C, this sample still exhibits a reversible capacity of 117 mA h g−1, comparing to 86 mA h g−1 for TiO2/C. The enhanced electrochemical performances can be ascribed to the improvement of the conductivity and the structural stability of TiO2 due to Zn2+-doping. Therefore, Ti0.94Zn0.06O2/C is an attractive anode material of sodium-ion batteries.