Effect of treated temperature on structure and performance of LiCoO2 coated by Li4Ti5O12

Abstract

The Li4Ti5O12 (LTO)-coated LiCoO2 powders treated at different temperatures (t=500, 600, 700 and 900°C) and coated contents (x=0, 3%, 5%, 10% and 15%) were prepared. The effects of treated temperatures on structure and performance of LiCoO2 coated by LTO particles have been investigated by X-ray diffraction (XRD) and the galvanostatic charge–discharge test at the high upper voltage limit of 4.5V. 3wt.% and 5wt.% LTO-coated materials expose the absence of secondary phase peaks in the range of the diffraction patterns below 700°C, and distinct additional peaks start appearing when the treated temperature arrives at 900°C. The diffraction patterns of the 15wt.% LTO-coated LiCoO2 shift toward higher angles compared to the other coated and bare LiCoO2. The 3wt.% LTO-coated LiCoO2 cathodes treated at 500, 700 and 900°C exhibit discharge capacities of 157, 162 and 140mAhg−1, respectively, versus capacities of 82mAhg−1 for the uncoated cathodes after 40 cycles. The LTO coatings are shown to suppress the capacity fade by reducing cell polarization.