Improving the sodiation performance of Na2Ti3O7 through Nb-doping

Abstract

Na2Ti3O7 has attracted increasing attention as a promising anode material for Na-ion batteries. However, the low electronic conductivity of Na2Ti3O7 brings about kinetic problems for sodiation. In this study, we report Nb-doped Na2Ti3O7 synthesized from a facile sol-gel method. The obtained Na2Ti2.97Nb0.03O7 has increased unit cell volume and lowered band gap compared to the pristine Na2Ti3O7. The Na2Ti2.97Nb0.03O7 shows a high reversible capacity of 189.7mAhg−1 at 0.2C, a great high-rate performance of 89.4mAhg−1 at 5C, and great cyclability of 78.5% after 500 cycles. Specifically, the rate capability of Na2Ti2.97Nb0.03O7 is considerably superior to that of the pristine Na2Ti3O7. The improved sodiation performance suggests Nb-doping is an effective modification for Na2Ti3O7 anode materials.