Preparation of Li_4Ti_5O_(12) by solution ion-exchange of sodium titanate nanotube and evaluation of electrochemical performance

摘要

Nano-sized spinel lithium titanate (Li_4Ti_5O _(12)) was synthesized using sodium titanate nanotube as precursor via a facile solution ion-exchange method in association with subsequent calcination treatment at relatively low temperature. The influences of precursors, ion-exchange condition, and calcination temperature on the microstructure and electrochemical performance of the products were studied. Results indicate that pure-phase Li_4Ti_5O_(12) can be harvested from sodium titanate nanotube precursor through an ion-exchanging at room temperature and calcination at 500 C. The products exhibit a better performance as Li-ion battery anode material than the counterparts prepared from protonic titanate nanotube (H-titanate) precursor. The reason may lie in that sodium titanate nanotube is easier than protonic titanate nanotube to synthesize lithium titanate without TiO_2 impurity, resulting in reduced electron transfer ability and Li-ion transport ability. The capacity of Li _4Ti_5O_(12) prepared from sodium titanate nanotube is 146 mAh/g at 10 C, and it has only 0.7 % decay after 200 charge/discharge cycles.