Titanium-based materials as anode materials for sodium ion batteries

 Titanium-based materials have attracted increasing attention in recent years as anode materials for sodium ion batteries due to their properties of environmentally friendly, safe, and good stability. However, titanium-based materials show wide band gap, poor electronic conductivity, and low specific capacity, which limit their development and application in sodium ion batteries. This review focuses on the electrochemical properties, modification, and sodium storage mechanism of three titanium-based materials, which are TiO2, Na2TinO2n+1, and NaTi2(PO4)3. The problems and prospect are also pointed out for these materials. Future researches could be focused on the following aspects: ① investigating the electrochemical mechanism of titanium-based materials deeply and systematically; ② the anions/cations doping effects on the structural, electronic and electrochemical  properties of titanium-based materials; ③ the synergistic effect of titanium-based materials and anode materials with high specific capacity; ④ the design of hierarchically structure and three-dimensional structure for titanium-based materials;⑤ exploring titanium-based materials with novel structures.