Combined Modification of Dual-Phase Li 4 Ti 5 O 12 -TiO 2 by Lithium Zirconates to Optimize Rate Capabilities and Cyclability.

The low electrical conductivity and ordinary lithium-ion transfer capability of Li4 Ti5 O12 restrict its application to some degree. In this work, dual-phase Li4 Ti5 O12 -TiO2 (LTOT) was modified by composite zirconates of Li2 ZrO3 , Li6 Zr2 O7 (LZO) to boost the rate capabilities and cyclability. When the homogeneous mixture of LiNO3 , Zr(NO3 )4 ·5H2 O and LTOT was roasted at 700 °C for 5 h, the obtained composite achieved a superior reversible capacity of 183.2 mAh g-1 to the pure Li4 Ti5 O12 after cycling at 100 mA g-1 for 100 times due to the existence of a scrap of TiO2 . Meanwhile, when the composite was cycled by consecutively doubling the current density between 100 and 1600 mA g-1 , the corresponding reversible capacities are 183.2, 179.1, 176.5, 173.3, and 169.3 mAh g-1 , signifying the prominent rate capabilities. Even undergoing 1400 charge/discharge cycles at 500 mA g-1 , a reversible capacity of 144.7 mAh g-1 was still attained, denoting splendid cyclability. From a series of comparative experiments and systematic characterizations, the formation of LZO meliorated both the Li+ migration kinetics and electrical conductivity on account of the concomitant superficial Zr4+ doping, responsible for the comprehensive elevation of the electrochemical performance.