Synthesis and Electrochemical Properties of Nanocrystalline LiFePO4 Obtained by Different Methods

Abstract

ABSTRACT: Nanocrystalline LiFePO 4 powders were prepared at 660-670 o C in an Ar atmosphere using two dif-ferent synthetic routes, solid-state and sol-gel. Both materials showed well-developed XRD patternswithout any impurity peaks. Particles composed in the range of 200-300 nm from the solid-statemethod, and 50-100 nm from the sol-gel method, were confirmed through scanning electronmicroscopy and dynamic light scattering. The LiFePO 4 obtained by the sol-gel method offered a highdischarge capacity (153 mAh/g) and stable discharge behavior, even at elevated temperatures (50 and60 o C), whereas poor electrochemical performance was observed from the solid-state method. Ratecapability studies for sol gel-derived LiFePO 4 ranged from 0.2 to 30 C, which revealed excellentretention over 70 cycles with a 99.9% capacity. Keywords : LiFePO 4 , Solid-state method, Sol-gel method, Cathode material, Lithium secondary battery Received May 10, 2011 : Accepted June 29, 2011 1. Introduction In the recent past, researchers have focused upon agroup of lithium iron-containing compounds that incor-porate polyanions of the class XO