New solid-state synthesis routine and mechanism for LiFePO4 using LiF as lithium precursor

dLi(2)CO(3) and LiOH . H2O are widely used as Li-precursors to prepare LiFePO4 in solid-phase reactions. However, impurities are often found in the final product unless the sintering temperature is increased to 800 degreesC. Here, we report that lithium fluoride (LiF) can also be used as Li-precursor for solid-phase synthesis of LiFePO4 and very pure olivine phase was obtained even with sintering at a relatively low temperature (600 degreesC). Consequently, the product has smaller particle size (about 500 nm), which is beneficial for Li-extraction/insertion in view of kinetics. As for cathode material for Li-ion batteries, LiFePO4 obtained from LiF shows high Li-storage capacity of 151 mAh g(-1) at small current density of 10 mA g(-1) (1/15 C) and maintains capacity of 54.8 mAh g(-1) at 1500 mA g(-1) (10 C). The solid-state reaction mechanisms using LiF and Li2CO3 precursors are compared based on XRD and TG-DSC. (C) 2004 Elsevier Inc. All rights reserved.