Study of improved electrochemical performance of LiFePO_4/C electrode for LIB

Lithium iron phosphate is a most promising cathode material for Li-ion batteries (LIB). But the key barrier limiting its application is extremely low electronic conductivity. Meanwhile the low electron conductivity can be improved by preparing LiFePO4 with carbon modified.LiFePO4/C was synthesized by high temperature solid-state reaction using iron (Ⅱ) oxalate, ammonium di-hydrogen phosphate and lithium carbonate with a kind of organic compound (CR) that can he dissolved in the dispersant (ethanol) as carbon sources added to the synthetic precursor in this paper. The samples were characterized by X-ray diffraction, scanning electron microscope observations, charge/discharge test, cyclic voltammetry and carbon analysis. It was believed that the synthesized LiFePO4/C with perfect olivine structure by X-ray diffraction. The carbon brought about two advantages: (i) an optimized particle size of LiFePO4, and (ii) increasing the electronic conductivity and Li(superscript +) diffusivity. The cathode material Could demonstrate a charge/discharge flat voltage of 3.4V (Vs Li(superscript +)/Li). Especially the active material with 20% organic added according to the final product of LiFePO4 showed very good electrochemical performance reaching about initial 162.0mAh/g specific capacity at 0.1℃ rate and could also keep excellent discharge capacity even at 3℃ rate (510mA/g) current and good cycle performance. The carbon content in the final production was only 5.29% (mass fraction).