Synthesis and effect of forming Fe2P phase on the physics and electrochemical properties of LiFePO4/C materials

Series LiFePO4/C materials have been prepared by a so-called reformative solid-coordination method, which uses citric acid as the coordination agent and carbon source. A monodenate coordination band of -COO-M was proved to form gradually and that would help to disperse Li+ or Fe2+ among the homogeneous gel during the grinding process. Impure phase Fe2P was detected out among the LiFePO4/C composites with increasing annealed temperature. The remnant coating carbon was considered to be the reductive under the pure nitrogen gas. The amounts of carbon, particle size and morphology were investigated in detail and all the results showed to be related to the formation of Fe2P. The electro-conductive Fe2P phase among LiFePO4/C composites acts as important role in increasing electronic conductivity and evidently improves the electrochemical performance of LiFePO4/C including the less polarization phenomenon, comparatively high reversible capability, stable cycling performance and slight trend of less loss of rate capability. (c) 2006 Elsevier B.V. All rights reserved.