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

The Li5Ti5O12 (LTO)-coated LiCoO2 powders treated at different temperatures (t=500, 600, 700 and 900 degrees 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 4.5 V.3 wt.% and 5 wt.% LTO-coated materials expose the absence of secondary phase peaks in the range of the diffraction patterns below 700 degrees C, and distinct additional peaks start appearing when the treated temperature arrives at 900 degrees C. The diffraction patterns of the 15 wt.% LTO-coated LiCoO2 shift toward higher angles compared to the other coated and bare LiCoO2. The 3 wt.% LTO-coated LiCoO2 cathodes treated at 500, 700 and 900 degrees C exhibit discharge capacities of 157, 162 and 140 mAh g(-1), respectively, versus capacities of 82 mAh g(-1) for the uncoated cathodes after 40 cycles. The LTO coatings are shown to suppress the capacity fade by reducing cell polarization. (C) 2011 Elsevier B.V. All rights reserved.