ZnO incorporated LiFePO4 for high rate electrochemical performance in lithium ion rechargeable batteries

In order to improve the electrical conductivity of LiFePO4 (LFP) cathode, ZnO/Carbon was incorporated in the cathode by wet vibratory ball milling ZnO, Polyethylene glycol (PEG) and LFP particles together. Herein, polyethylene glycol (PEG) was used as both dispersant during ball milling and carbon source after calcination process. The uniformly dispersed carbon and ZnO on the surface of LFP led to a good electronic contact between the LFP grains. The charge/discharge rate in the range of C/10 to 10C and cycle performance at C/10 for 50 cycles was tested at room temperature. The LFP/ZnO/Carbon composite cathode showed a high capacity of 158.9 mAhg(-1), displayed excellent high rate and cyclic performance due to high amounts of graphitic carbon transformed by ZnO used as a catalyst during calcination process. The decrease in capacity was within 31% at a discharge rate of 10C and less than 3% after 50 cycles at C/10 rate. The LFP/ZnO/Carbon composite was characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM), high resolution Transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Micro-Raman, and specific surface area. Electrochemical properties were measured using electrochemical impedance spectroscopy (EIS), potentiostatic intermittent titration technique (PITT) and galvanostatic measurements. (C) 2012 Elsevier B.V. All rights reserved.