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

Abstract

High-tap-density olivine CLiFePO4, which is used as a positive electrode material in lithium-ion secondary batteries, was prepared via coprecipitation. The CLiFePO4 powders were prepared at various calcination temperatures between 650 and 850C. 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 CLiFePO4 with a Pnma space group and a high tap density of 1.09 g cm3 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 12 µm particle size, while the particle size of the primary particles was less than 100 nm. The CLiFePO4 materials prepared at 800C exhibited an excellent rate capability of 150.8 mAh g1 at the 0.1 C discharge rate and 106.7 mAh g1 at the 10 C discharge rate.