Synthesis and electrochemical characterization of Li2FexMn1 − xSiO4/C (0 ≦ x ≦ 0.8) nanocomposite cathode for lithium-ion batteries

Li2MnSiO4/C nanocomposites were synthesized by a novel synthesis route, i.e., a combination of spray pyrolysis and wet ball milling followed by annealing. X-ray diffraction analysis indicated that the peaks of the Li2MnSiO4/C nanocomposites were indexed to the orthorhombic structure in Pmn21 space group. Field-emission scanning electron microscopy and transmission electron microscopy together with energy-dispersive spectroscopy verified that the Li2MnSiO4/C nanocomposites were agglomerates of Li2MnSiO4 primary particles with a geometric mean diameter of 65 nm, and that carbon was well distributed on the surface of these agglomerates. Moreover, Li2FexMn1 − xSiO4/C (0 < x ≦ 0.8) nanocomposites were prepared to investigate the effect of substituting Fe for Mn on their electrochemical properties. The Li2FexMn1 − xSiO4/C (0 ≦ x ≦ 0.8) nanocomposites were used as cathode materials for rechargeable lithium batteries, and electrochemical measurements were carried out using Li|1 M LiPF6 in EC:DMC = 1:1|Li2FexMn1 − xSiO4/C cells at room temperature. The Li2MnSiO4/C nanocomposite electrodes delivered first-discharge capacities of 197 and 130 mAh g− 1 at 0.05 and 1 C, respectively. However, they showed poor cyclability due to the transformation to amorphous Li2MnSiO4 during the first charge. On the other hand, a Li2Fe0.5Mn0.5SiO4/C nanocomposite cathode delivered a higher discharge capacity of 149 mAh g− 1 at 1 C, and showed better cyclability than Li2MnSiO4/C nanocomposites.