Enhanced high-voltage electrochemical performance of LiCoO2 coated with ZrOxFy

LiCoO2 is successfully coated with oxyfluoride ZrOxFy by a chemical deposition method for the first time. The formation of a uniform coating layer on the surface of the cathode particles is confirmed by SEM, TEM, EDX and XPS. The coated sample maintains the pristine layered structure according to the XRD result. Compared with pristine LiCoO2, the ZrOxFy-coated sample exhibits enhanced electrochemical performance especially at high cutoff voltage. Similar discharge capacities are delivered by both pristine and coated samples in various voltage ranges. However, the coated sample shows improved cycling performance, maintaining 56.4%, 32.8% capacity retention after 200 cycles, which is much more than 30.3%, 10.5% that is shown by the pristine sample in the voltage range of 3.0-4.5 V and 3.0-4.6 V, respectively. (C) 2014 Elsevier B.V. All rights reserved.