The effect of morphological properties on the electrochemical behavior of high tap density C-LiFePO4 prepared via coprecipitation

High-tap-density olivine C-LiFePO4, which is used as a positive electrode material in lithium-ion secondary batteries, was prepared via coprecipitation. The C-LiFePO4 powders were prepared at various calcination temperatures between 650 and 850 degrees C. The structural, electrochemical, and morphological properties, as well as the thermal stability of the prepared powders, were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy, and elemental analysis. Highly crystalline C-LiFePO4 with a Pnma space group and a high tap density of 1.09 g cm(-3) was obtained. Elemental analysis showed that the final product contained about 3 wt % carbon as a result of the carbon-coating process. SEM showed that the prepared materials consisted of secondary agglomerates with a 1-2 mu m particle size, while the particle size of the primary particles was less than 100 nm. The C-LiFePO4 materials prepared at 800 degrees C exhibited an excellent rate capability of 150.8 mAh g(-1) at the 0.1 C discharge rate and 106.7 mAh g(-1) at the 10 C discharge rate. (C) 2008 The Electrochemical Society.