Effects of Cr doping on the electrochemical performance of LiV(PO) cathode material for lithium ion batteries.

A series of Cr-doped LiVCr(PO) ( x = 0, 0.1, 0.25, and 0.5) samples are prepared by a sol-gel method. The effects of Cr doping on the physical and chemical characteristics of LiV(PO) are investigated. Compared with the XRD pattern of the undoped sample, the XRD patterns of the Cr-doped samples have no extra reflections, which indicates that Cr enters the structure of LiV(PO). As indicated by the charge-discharge measurements, the Cr-doped LiVCr(PO) ( x = 0.1, 0.25, and 0.5) samples exhibit lower initial capacities than the undoped sample at the 0.2 C rate. However, both the discharge capacity and cycling performance at high rates (e.g., 1 and 2 C) are enhanced with proper amount of Cr doping ( x = 0.1). The highest discharge capacity and capacity retention at the rates of 1 and 2 C are obtained for LiVCr(PO). The improvement of the electrochemical performance can be attributed to the higher crystal stability and smaller particle size induced by Cr doping. [ABSTRACT FROM AUTHOR]