High‐rate Lithium Iron(II) Phosphate as Cathode Material for Rechargeable Lithium Batteries

Abstract

Abstract High‐rate carbon coated LiFePO 4 was synthesized by citric acid assistant aqueous chemical route employing polyethyleneoxide as the carbon source. The structural and electrochemical properties were intensively investigated by thermogravimetry, powder X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge‐discharge tests. The results of structural tests showed that the material consisted of small LiFePO 4 particles of good phase purity and the particles of the material were coated and connected with approximate 5 wt% incompact porous carbon. The material performed very well in electrochemical measurements, and was suitable for high‐rate charge and discharge. The material exhibited stable discharge capacities of 120, 90 and 60 mAh·g −1 at 5 C, 10 C and 20 C rates respectively (1 C=150 mA·g −1 , charge at 1 C).