A layered sodium titanate as promising anode material for sodium ion batteries

Abstract

Sodium ion batteries have recently received great attention for large-scale energy applications because of the abundance and low cost of sodium source. Although some cathode materials with desirable electrochemical properties have been proposed, it's quite challenging to develop suitable anode materials with high energy density and good cyclability for sodium ion batteries. Herein, we report a layered material, 03-NaTiO2, that delivers 130mAhg-1 of reversible capacity and presents excellent cyclability with capacity retention over 97.5% after 40 cycles and high rate capability. Furthermore, by coupling the electrochemical process with in situ X-ray diffraction, the structure evolution and variation of cell parameters corresponding to an 03-03' phase transition during sodium deintercalation is investigated. Unusual lattice parameter variation was observed by in situ XRD, which can be related to the structure modulation with varying Na vacancy ordering. An irreversible structural modification upon overcharging is also confirmed by in situ XRD. In summary, our work demonstrates that 03-NaTiO2 is a very promising anode material for sodium ion batteries with high energy density.