High-rate LiFePO4 electrode material synthesized by a novel route from FePO4 • 4H2O

A LiFePO4 material with ordered olivine structure is synthesized from amorphous FePO4 center dot 4H(2)O through a solid-liquid phase reaction agent, followed by thermal conversions of the intermediate NH4FEPO4 in the presence of LiOOCH3 center dot 2H(2)O. Simultaneous thermagravimetric-differential thermal analysis indicates that the crystallization mainly in the range 100-300 nm is observed by using by using scanning electron microscopy of the resulting LiFePO4 powder with a particle size mainly in the range 100-300 nm is observed by using scanning electron microscopy. As an electrode material for rechargeable lithium batteries, the LiFePO4 sample delivers a discharge capacity of 167 mA h g(-1) at constant current of 17 mA g(-1) (0.1 C rate throughout this study nC rate means that rated capacity of LiFePO4 (170 mA h g(-1)) is charged or discharged completely in 1/n hour), approaching the theoretical value of 170 mA h g(-1). Moreover, the electrode shows excellent high-rate charge and discharge capability and high-rate charge under 5 C and 10 C rate conditions. With a conventional charge mode, that is, 5 C rate charging to 4.2 V and then keeping this voltage until the charge current is decreased to 0.1 C rate, a discharge capacity of ca. 134 mA h g(-1) and cycling efficiency of 99.2-99.6% can be obtained at 5 C rate.