Metal-organic framework derived vanadium-doped TiO2@carbon nanotablets for high-performance sodium storage

• V-dopants were successfully incorporated into MIL-125 via solvothermal method. • V-doped TiO2@carbon was prepared by carbonizing the V-doped MIL-125. • V-doped TiO2@carbon showed much enhanced sodium storage performance. • V-doping of TiO2 enhanced the electronic/ionic transfer rate. Titanium dioxide (TiO 2 ) as a potential anode material for sodium-ion batteries (SIBs) suffers from the intrinsic poor electronic conductivity and sluggish ionic diffusivity, thus usually leading to the inferior electrochemical performance. Herein, we demonstrate a facile strategy to enhance the sodium storage performance of TiO 2 via vanadium (V) doping, using the pre-synthesized V-doped Ti-based metal–organic framework (MOF, MIL-125) as the precursor, which can be converted into the V-doped TiO 2 with simultaneous carbon hybridization and controlled V-doping amount (denote as V x TiO 2 @C, where × represents the V/Ti molar ratio (R V/Ti )). V-doping not only affects the morphology of the MIL-125 changing from thick to thin nanotablets, but also greatly enhances the electrochemical performance of the V x TiO 2 @C. When used as an anode for SIBs, the V 0.1 TiO 2 @C exhibits a much higher reversible capacity of 211 mAh/g than that for the undoped TiO 2 @C (only 156 mAh/g) after 150 cycles at 100 mA/g. Even after high-rate long-term cycling, the V 0.1 TiO 2 @C can still display a capacity of 180 mAh/g with a high capacity retention of 137% at 1000 mA/g after 4500 cycles. Structural/electrochemical measurements reveal that V-doping induces the formation of oxygen vacancies as well as Ti 3+ species, which efficiently improve the electric conductivity and the ion diffusivity of the electrode. Meanwhile, the thinner V 0.1 TiO 2 @C nanotablets with porous structure and carbon hybridization could facilitate the ion/electron transfer with shortened diffusion pathways.