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.

Graphical abstractSEM and TEM equipped with EDS observation revealed that the primary particle size of Li2MnSiO4/C nanocomposites was reduced to several tens of nanometers by wet ball milling the microprecursor powders prepared by spray pyrolysis. Furthermore, the conductive carbon was well distributed on the surface of the agglomerates of Li2MnSiO4 particles.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The Li2FexMn1 − xSiO4/C nanocomposites were prepared by a novel synthesis route. ► The primary particle size of the Li2MnSiO4/C nanocomposites was 65 nm. ► The Li2MnSiO4/C nanocomposites delivered the discharge capacity of 197 mAh g− 1. ► The Li2Fe0.5Mn0.5SiO4/C nanocomposites showed better cyclability.