Synthesis of Li2FeSiO4/C nanocomposite cathodes for lithium batteries by a novel synthesis route and their electrochemical properties

Li2FeSiO4/C nanocomposites were synthesized by a novel synthesis route, i.e., a combination of spray pyrolysis and wet ball-milling followed by annealing. The effect of process parameters such as spray pyrolysis temperature, ball-milling time, carbon content in the wet ball-milling process and annealing temperature on the physical and electrochemical properties of Li2FeSiO4/C nanocomposites was investigated. The final sample was identified as Li2FeSiO4 with a P2(1) monoclinic structure by X-ray diffraction analysis. Field-emission scanning electron microscopy and transmission electron microscopy with energy-dispersive spectroscopy verified that the Li2FeSiO4/C nanocomposites are agglomerates of Li2FeSiO4 primary particles with a geometric mean diameter of 65 nm and that the carbon was well-distributed on the surface of the agglomerates. A Li2FeSiO4/C nanocomposite sample was used as an electrode material for rechargeable lithium batteries, and electrochemical measurements were carried out by using Li vertical bar 1 M LiPF6 in EC: DMC = 1:1 vertical bar Li2FeSiO4/C cells at room temperature. The Li2FeSiO4/C nanocomposite electrode delivered a first discharge capacity of 154 mAh g(-1) at 0.05 C, corresponding to 93% of the theoretical value. Furthermore, the cycleability and rate capability of the cells were good. (C) 2011 Elsevier B.V. All rights reserved.