Physical and electrochemical properties of mix-doped lithium iron phosphate as cathode material for lithium ion battery

The Li0.98Al0.02FePO4/C (2.0 wt.%) mix-doped composite had been synthesized by adding aluminum stearate to the react precursors through solid-state reaction. The mix-doping method does not affect the olivine structure of the cathode but greatly improves its kinetics in terms of capacity delivery, cycle life and rate capability. Such an enhancement of the electrochemical properties has been ascribed to the increase of intra- and inter-crystal electronic conductivity and the reduction of the particle size, these two effects being promoted by the co-existence of the lattice doping element (Al3+) and the non-lattice doping element (C). Overcharge test indicates that this composite has excellent safety performances.