The Effect of Morphological Properties on the Electrochemical Behavior of High Tap Density C–LiFePO[sub 4] Prepared via Coprecipitation

High-tap-density olivine C-LiFePO 4 , which is used as a positive electrode material in lithium-ion secondary batteries, was prepared via coprecipitation. The C-LiFePO 4 powders were prepared at various calcination temperatures between 650 and 850°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-LiFePO 4 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 μm particle size, while the particle size of the primary particles was less than 100 nm. The C-LiFePΟ 4 materials prepared at 800°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.