Synthesis of LiFePO4 by a Novel Ultra Fast Combustion Method

Olivine-type LiFePO4 has been considered as one of the most promising cathode materials for lithium-ion rechargeable batteries due to its cost-effectiveness, nontoxicity, environmental benignity and relatively high theoretical capacity (170 mAh/g). On comparison to the commonly used transition oxides such as LiCoO2, LiNiO2, and LiMn2O4, LiFePO4 is observed to display high thermal stability in the charged state due to its robust structure, in which the strong covalent bonding between the oxygen and phosphor ions forms polyanion (PO4) molecular unit [1]. Although it has many advantages, LiFePO4 suffers intrinsic limitations of low electronic conductivity and slow lithium ion diffusion rate across the LiFePO4/FePO4 interface. Several research groups have tried to improve its electronic conductivity and lithium ion diffusivity by either carbon coating/additives that aid in conduction process or doping with supervalent metals into Li ion sites [2-6]. Among them, the recent alternative to synthesize nanoparticle sized LiFePO4 has been aimed at achieving high rate capability [8-10], since nanoparticles facilitate shorter ion diffusion paths through the lattice from the core of the particles to the surface, thereby leading to excellent electrochemical performances with good capacity retention.