One-Pot Synthesis of Multi-Morphous LiFePO4 Nanoparticles in Polyol Medium

Nano-LiFePO4 possessing plate, rod and multi shaped morphologies are synthesized by a low temperature solvothermal route. The prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies. The XRD patterns indicate the formation of phase-pure orthorhombic olivine structure designated to the space group of Pnma. Synthesized samples reveal plate, rod and multi-morphous (a combination of plate, rod and spherical shaped particles) morphologies, respectively, in the SEM study. The growth of the plate-type olivine nanocrystals is identified to be along [100] and [010] crystallographic directions while the rod-shaped particles indicate growth along the crystallographic ac planes, as estimated from the TEM studies. The first discharge capacities of the olivine with plate-type, rod-type, and multi-morphous olivine samples are 131, 144, and 161 mAhg(-1) with minimal capacity fading for deeply extended cycles, respectively. Especially, in rate performance, the multi-morphous LiFePO4 sample having mixed morphologies maintains capacity of about 110 mAh g(-1) until 8 C rates, while the plate and rod samples show severe capacity decline at corresponding rates. The reason for the high rate-performance of multi-morphous LiFePO4 cathode is ascertained to the nano-sized particles and enhanced intimate connectivity between the multi-shaped nanoparticles. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3581029]