Significant Enhancement in the Electrochemical Performances of a Nanostructured Sodium Titanate Anode by Molybdenum Doping for Applications as Sodium-Ion Batteries

Sodium titanate is considered as one of the most promising anode materials for sodium-ion batteries without any serious safety concerns due to its high theoretical capacity at sufficiently low voltage. However, its low electrical conductivity severely restricts the electrochemical performances as an anode for sodium-ion batteries. Because suitable doping is always found to be a trump card strategy to especially enhance the conductivity, a molybdenum-doped sodium titanate nanostructured anode was successfully synthesized for the first time using the solvothermal method. Molybdenum-doped sodium titanate electrode materials showed superior electrochemical performances than the pristine sample. On more precise consideration, the sodium titanate electrode doped with 15 wt % molybdenum not only delivers ∼24% high reversible capacity at a high current density of 1 A g–1 in comparison to the pure sodium titanate electrode but also maintains it until 2500 cycles. It is believed that the improved electrochemical performances are mainly contributed by the combination of enhanced electrical conductivity and oxygen vacancy generated in the sodium titanate framework as a result of molybdenum doping. Molybdenum doping may also allow Na+ ion diffusion through multiple pathways within the sodium titanate crystal lattice and increase the transport rate of Na+ ions.