Synthesis and electrochemical properties of nanosized carbon-coated Li _1-3xLa _xFePo ₄ composites

Nanosized carbon-coated Li _1-3xLa _xFePO ₄ composites were synthesized using a fast, easy, microwave assisted, room-temperature, solid-state method. A lanthanum precursor was used to improve the electronic conductivity of LiFePO ₄. The particle structure of the as-synthesized samples was observed using transmission electron microscopy. The results indicated that a uniform and continuous carbon layer was formed on the surface of Li _1-3xLa _xFePO ₄ particles. Electrochemical techniques, such as cyclic voltammetry, charge/discharge test, and electrochemical impedance spectroscopy were used to investigate the electrochemical performance of the samples. The results of electrochemical measurements revealed that the carbon coating and lanthanum doping provided an initial discharge capacity of 145 mA h/g with excellent rate capacity and long cycling stability. These advantages, coupled with the low cost, the high thermal stability, and the environmental friendliness of the raw materials, render Li _1-3xLa _xFePO ₄/C composites attractive for practical and large-scale applications. © Springer-Verlag 2009.