Improving the high rate performance of Li4Ti5O12 through divalent zinc substitution

Microscale Li4Ti5-xZnxO12 (0 <= x <= 0.2) particles with high phase purity were synthesized by a simple solid-state reaction. The effect of the zinc doping on the physicochemical properties of Li4Ti5O12 (LTO) was extensively studied by TG-DSC, XRD, Raman spectroscopy, SEM, CV, EIS, and galvanostatic charge discharge testing. The crystallization of lithium titanate oxide forms at about 750 degrees C. The lattice parameter of the Zn-doped LTO samples is slightly smaller than that for the pure LTO samples, and zinc doping does not change the basic Li4Ti5O12 structure. Even though the material has a particle size of 1-2 mu m, Zn-doped LTO shows very high excellent capacity retention between 0 and 2.5 V. Especially, in rate performance, the Li4Ti4.8Zn0.2O12 sample maintains capacity of about 180 mAh g(-1) until 5 C rates after 200 cycles, while the pure LTO sample shows severe capacity decline at corresponding rates. The reason for the high rate performance of Zn-doped LTO anode is ascertained to the diffusion coefficient (D-Li) and reversible intercalation and deintercalation of lithium ion. The superior cycling performance and wide discharge voltage range, as well as simple synthesis route and low synthesis cost of the Zn-doped LTO are expected to show a potential commercial application. (C) 2012 Elsevier B.V. All rights reserved.