An ionic liquid synthesis route for mixed-phase sodium titanate (Na2Ti3O7 and Na2Ti6O13) rods as an anode for sodium-ion batteries

Sodium ion batteries represent a sustainable alternative to Li-ion technologies. Challenges with material properties remain, however, particularly with regards the performance of anodes. We report a rapid, energy-efficient ionic liquid synthesis method for mixed phase Na2Ti3O7 and Na2Ti6O13 rods. This method is based on a novel phase-transfer route which produces pure functional materials via a dehydrated IL. The structure of the synthesised materials was characterised using powder X-ray diffraction, which confirms the formation of a mixed Na2Ti3O7 and Na2Ti6O13 phase, with majority Na2Ti3O7 phase, in contrast to previous synthesis methods. Scanning and transmission electron microscopy analysis reveals a rod morphology, with an average diameter and length of 87 nm ± 3 nm and 1.37 μm ± 0.07 μm, respectively. The initial discharge and charge capacity of Na2Ti3O7 nanorods were measured as 325.20 mA h g−1 and 149.07 mA h g−1, respectively, at 10 mA g−1 between 0.01–2.5 V. We attribute the enhanced performance to the higher weight fraction of Na2Ti3O7 phase vs. previous reports, demonstrating the potential of the ionic liquid method when applied to sodium titanate materials.