Improved electrochemical performance of 5 V LiCoPO4 cathode materials via yttrium doping

Pure and Y-doped LiCoPO4 samples are prepared by a citric acid-based sol-gel route followed by heat treatment. X-ray diffraction, scanning electron microscopy and charge-discharge tests show that a small amount of Y3+ doping can significantly improve the capacity delivery and cycling properties of LiCoPO4 without affecting its structural properties. Y-doped LiCoPO4 (x = 0.01) cathode material presents a high discharge capacity of 154.3 mAh g(-1) (0.1 C) at room temperature. Cyclic voltammetric and electrochemical impedance spectra tests disclose that the Li-ion diffusion, the reversibility of lithium extraction/insertion, electrical conductivity and electrochemical reaction are significantly improved in Y-doped LiCoPO4. (C) 2013 Elsevier B.V. All rights reserved.