Fabrication of promising LiFePO4/C composite with a core-shell structure by a moderate in situ carbothermal reduction method

How to improve the power density of olivine LiFePO4 has recently become one of the most attractive topics of both scientific and industrial interests. Therefore, nanostructured electrodes have been widely investigated to satisfy such needs. However, the complicated and high-temperature sintering process is usually involved for preparing high-performance cathode materials based on high-quality crystals. In order to solve these problems, here, a promising LiFePO4/C composite electrode material is synthesized by an in situ carbothermal reduction method at low temperature using a low-cost Fe3+ salt as the iron source, soluble starch sol as carbon sources and reducing agent. The synthesized LiFePO4/C composite shows highly crystalline, ultrafine sphere-like particles and a desirable core-shell structure with uniform carbon film on the surface of nano-crystal LiFePO4, which could inherit the morphology of FePO4 precursor. Galvanostatic battery testing shows that LiFePO4/C composite delivers 161 and 122 mAh/g at 0.2 C and 5 C rates, respectively, and exhibits desirable capacity retention after 500 cycles at 5 C. Remarkably, even at a high current density of 20 C, the cell still presents good cycle retention. (C) 2012 Elsevier Ltd. All rights reserved.