A new synthesis route to nanocrystalline olivine phosphates and their electrochemical properties.

ABSTRACT

LiFePO4 nanoparticles were synthesized in various polyol mediums without any further heating. The LiFePO4 samples synthesized in polyol mediums exhibited average sizes of 20, 20, 50, and 50 nm with orthorhombic-like shapes. The XRD patterns were indexed on the basis of an olivine structure (space group Pnma) except for the sample prepared in EG polyol medium. The LiFePO4 samples prepared in EG, DEG, TEG, and TrEG polyol mediums show the reversible capacity of 120 mA h/g, 144 mA h/g, 159 mA h/g, and 167 mA h/g at current density of 0.1 mA/cm2 with no capacity fading and excellent cycle retentions during extended cycles. Especially, the samples showed the excellent performances at high rate of 30 C and 60 C with high capacity retention. It is a speculation that nanometer size materials (approximately 50 nm) and a uniform size-distribution with highly crystallined phase may affect the excellent performances at high rate current densities.