A Facile Route for Synthesis of LiFePO4/C Cathode Material with Nano-sized Primary Particles

A facile and practical route was introduced to prepare LiFePO₄/C cathode material with nano-sized primary particles and excellent electrochemical performance. LiH₂PO₄ was synthesized by using H₃PO₄ and LiOH as raw materials. Then, as-prepared LiH₂PO₄, reduced iron powder and α-D-glucose were ball-milled, dried and sintered to prepare LiFePO₄/C. X-ray diffractometry was used to characterize LiH₂PO₄, ball-milled product and LiFePO₄/C. Differential scanning calorimeter-thermo gravimetric analysis was applied to investigate possible reactions in sintering and find suitable temperature for LiFePO₄ formation. Scanning electron microscopy was employed for the morphology of LiFePO₄/C. As-prepared LiH₂PO₄ is characterized to be in P21cn(33) space group, which reacts with reduced iron powder to form Li₃PO₄, Fe₃(PO₄)₂ and H₂ in ball-milling and sintering. The appropriate temperature for LiFePO₄/C synthesis is 541.3-976.7℃. LiFePO₄/C prepared at 700℃ presents nano-sized primary particles forming aggregates. Charge-discharge examination indicates that as-prepared LiFePO₄/C displays appreciable discharge capacities of 145 and 131 mA·h·g^-1 at 0.1 and 1 C respectively and excellent discharge capacity retention.