Tantalum-doped lithium titanate with enhanced performance for lithium-ion batteries

• Ta doping in Li4Ti5O12 would enlarge the lattice parameter of Li4Ti5O12.
• The ionic conductivity and electronic conductivity of Li4Ti5O12 are improved by Ta doping.
• The Li4Ti5O12 with only 0.1 at% Ta doping exhibits superior electrochemical performance.

A series of Tantalum-doped lithium titanate (Ta-doped Li4Ti5O12) samples have been successfully synthesized by one step solid-state method using TiO2, Li2CO3, and Ta2O5 as raw materials. The Li4Ti5O12 with only 0.1 at% Ta doping (Li4Ti4.995Ta0.005O12) exhibits higher rate capability and better cyclic stability than the pristine Li4Ti5O12. Li4Ti4.995Ta0.005O12 could deliver 95.1 mAh g−1 at 10C with much lower overpotential (216.1 mV) while the pristine Li4Ti5O12 delivers only 50.4 mAh g−1 at 10C with higher overpotential of 392.2 mV. As indicated by XRD, HRTEM and electrochemical characterizations, Ta doping in Li4Ti5O12 would enlarge the lattice parameter of the Li4Ti5O12, and facilitate the Li+ diffusion during the charge/discharge process. In addition, the higher charge compensation of the stoichiometric reduction of Ti4+ to Ti3+ by introducing Ta increases the electronic conductivity of Li4Ti5O12. The improved ionic conductivity and electronic conductivity are beneficial to the electrochemical performance of Li4Ti5O12. As a result, Ta doping is a new strategy for enhancing the electrochemical performance of Li4Ti5O12.