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 °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 μm, 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 (DLi) 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.