Synthesis of spherical LiFePO4/C via Ni doping

Spherical LiFePO4/C powders were synthesized by the conventional solid-state reaction method via Ni doping. Low-cost asphalt was used as both the reduction agent and the carbon source. An Ni-doped spherical LiFePO4/C composite exhibited better electrochemical performances compared to an un-doped one. It presented an initial discharge capacity of 161 mAhg(-1) at 0.1 C rate (the theoretical capacity of LiFePO4 with 5 wt% carbon is about 161 mAhg(-1)). After 50 cycles at 0.5 C rate, its capacity remained 137 mAhg(-1) (100% of the initial capacity) compared to 115 mAhg(-1) (92% of the initial capacity) for an un-doped one. The electrochemical impedance spectroscopy analysis and cyclic voltammograms results revealed that Ni doping could decrease the resistance of LiFePO4/C composite electrode drastically and improve its reversibility. (C) 2010 Elsevier Ltd. All rights reserved.