A mild process for the synthesis of Na2Ti3O7 as an anode material for sodium-ion batteries in deep eutectic solvent

Low capacity and poor cycle stability are two typical drawbacks of Na2Ti3O7 when applied to the sodium-ion batteries as electrode materials. Here, we successfully synthesized Na2Ti3O7 by a mild process in chloride/ethylene glycol-based deep eutectic solvent. The prepared Na2Ti3O7 overcomes the above drawbacks of Na2Ti3O7 which was synthesized by conventional methods. Our synthesized Na2Ti3O7 can deliver discharge capacities of 127mAhg(-1) after 50 cycles and 72mAhg(-1) after 2000 cycles at current density of 1C and 5C, respectively. This cheap and environmentally friendly Na2Ti3O7 exhibits excellent rate performance and cycling stability. In addition, we also further investigate the sodium storage mechanism of this product, the results show that pesudocapacitive behaviors account for a large proportion of its capacity.