Submicron-Sized Clusters of LiFePO_4-C Nanoparticles for Lithium-Ion Battery Cathodes

摘要

Submicron-sized clusters of LiFePO_4-C nanoparticles were synthesized using a rheological phase reaction method. X-ray diffraction (XRD), scanning electron microscope (SEM), and high resolution transmission electron microscope (HRTEM) observations show that the as-prepared LiFePO_4-C composite has good crystallinity consisting of submicron-sized clusters of carbon-coated LiFePO_4 nanoparticles with size of around 50 nm. Both the graphite and disordered carbon are observed in the LiFePO_4-C from the Raman spectroscopy and a low intensity ratio of the D band to that of the G band (I_D/I_G = 0.687) is obtained, confirming the high electronic conductivity of this material. The second-cycle discharge capacities are 169.6, 131.4, and 95.6 mAh·g~(-1) at 0.1, 1.0, and 5.0 G, respectively. Excellent cycling performance with a discharge capacity of 80.9 mAh·g~(-1) is still maintained even at a high current density of 10 C. Our results suggest that this material is a promising cathode material for lithium ion batteries.