Synthesis of LiFePO4/C nanocomposites by a novel process and their electrochemical properties

LiFePO4/C composites were successfully prepared by emulsion drip combustion in a fluidized bed reactor followed by heat treatment from the precursor solution; LiNO3, Fe(NO3)3·9H2O and H3PO4 were stoichiometrically dissolved in distilled water. The ordered LiFePO4 olivine structure could be obtained after the heat treatment of the as-prepared samples was performed at temperature ranges from 500 to 800 °C in N2 + 3% H2 atmosphere. It was also confirmed from the transmission electron microscopy (TEM) observation with electron diffraction spectrometry (EDS) that the final samples were LiFePO4/C composites with larger secondary particles. The LiFePO4/C composites were prepared at 600 °C and then annealed at 700 °C exhibited a first discharge capacity of 93 mAh g−1 at a 0.1 C rate, which corresponded to 55% of the theoretical capacity.The as-prepared sample at 600 °C by the emulsion drip combustion was milled in ethanol by a planetary ball-milling and then annealed at 700 °C for 4 h in N2 + 3% H2 atmosphere. It was clearly seen from scanning electron microscopy(SEM) and TEM images with EDS that the final sample was made up of agglomerates with approximately 100 nm primary particles covered with a thin carbon layer. As a result, LiFePO4/C nanocomposites could be successfully prepared by a combination of emulsion drip combustion and wet ball-milling followed by heat treatment. The LiFePO4/C nanocomposites delivered a first discharge capacity of 147 mAh g−1 (86% of theoretical capacity) at a 0.1 C rate. The capacity retention after 100 cycles for the cell was 98% at a 1 C rate.

► The novel preparation route of LiFePO4/C nanocomposites was developed.
► The emulsion drip combustion in a fluidized bed reactor was applied.
► The emulsion phase was used as the electronic conductive carbon source.
► The effect of wet ball-milling and annealing procedures were investigated.
► The physical and electrochemical properties of final materials were studied.