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 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.