Electrochemical Characteristics and Li+ Ion Intercalation Kinetics of Dual-Phase Li4Ti5O12/Li2TiO3 Composite in the Voltage Range 0-3 V

Li4Ti5O12, Li2TiO3, and dual-phase Li4Ti5O12/Li2TiO3 composite were prepared by sol gel method with average particle size of 1, 0.3, and 0.4 mu m, respectively. Though Li2TiO3 is electrochemically inactive, the rate capability of Li4Ti5O12/Li2TiO3 is comparable to that of Li4Ti5O12 at different current rates. Li4Ti5O12/Li2TiO3 also shows a good rate performance of 90 mA h g(-1) at a high rate of 10 C in the voltage range 1-3 V, attributable to increased interfaces in the composite. While Li4Ti5O12 delivers a capacity retention of 88.6% at 0.2 C over 50 cycles, Li4Ti5O12/Li2TiO3 exhibits no capacity fading at 0.2 C (40 cycles) and a capacity retention of 98.45% at 0.5 C (50 cycles). This highly stable cycling performance is attributed to the contribution of Li2TiO3 in preventing the undesirable reaction of Li4Ti5O12 with the electrolyte during cycling. Cyclic voltammetric curves of Li4Ti5O12/Li2TiO3 in the 0-3 V range exhibit two anodic peaks at 1.51 and 0.7-0.0 V, indicating two modes of lithium intercalation into the lattice sites of active material. Owing to enhanced intercalation/deintercalation kinetics in 0-3 V, the composite electrode delivers a superior rate performance of 203 mAh/g at 2.85 C and 140 mAh/g at 5.7 C with good reversible capacity retention over 100 cycles.