Carbon coated lithium cobalt phosphate for Li-ion batteries: Comparison of three coating techniques

Three techniques, i.e., pyrolysis of sucrose, spray of acetylene black, and propane vapor deposition, are adopted to coat carbon onto the surface of LiCoPO4 particles, and their effects are compared. The LiCoPO4/C composites are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS). The results show that the coating techniques determine the property of carbon films formed on the surface of LiCoPO4 particles, which further affect the performance of LiCoPO4. A complete and homogeneous carbon layer is the key to a high electrochemical activity and stable cycle performance. Among these LiCoPO4/C composites, the material processed via the deposition technique shows a more uniform carbon layer than that of the others, thus it exhibits a large reversible capacity of 130 mA h(-1) with favorable cyclability and rate capability in the voltage range of 3.0-5.0 V. (C) 2012 Elsevier B.V. All rights reserved.