A novel synthesis of LiFePO4/C from Fe2O3 without extra carbon or carbon-containing reductant

A novel synthesis of LiFePO4/C from Fe2O3 with no extra carbon or carbon-containing reductant was introduced: Fe2O3 (+NH4H2PO4)→Fe2P2O7(+Li2CO3+glucose)→LiFePO4/C. X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were utilized to characterize relevant products obtained in the synthetic procedure. The reaction of Fe2P2O7 and Li2CO3 was investigated by thermo-gravimetric and differential thermal analysis (TGA-DTA). Fe2O3 is completely reduced to Fe2P2O7 by NH4H2PO4 at 700 °C and Fe2P2O7 fully reacts with Li2CO3 to form LiFePO4 in the temperature range of 663.4-890 °C. The primary particles of LiFePO4/C samples prepared at 670, 700 and 750 °C respectively exhibit uniform morphology and narrow size distribution, 0.5-3 μm for those obtained at 670 and 700 °C and 0.5-5 μm for those obtained at 750 °C. LiFePO4/C (carbon content of 5.49%, mass fraction) made at 670 °C shows an appreciable average capacity of 153.2 mA·h/g at 0.1C in the first 50 cycles.