Facile synthesis of carbon coated LiFePO4 nanocomposite with excellent electrochemical performance through in situ formed lithium stearate pyrolysis route

Carbon coated LiFePO₄ (LiFePO₄/C) nanocomposite is successfully synthesized at a comparatively low temperature (400 °C) via a pyrolysis process of in situ formed lithium stearate. The obtained products are characterized by X-ray diffraction, electron microscopy, thermogravimetry, infrared and X-ray photoelectron spectroscopy. Experimental results indicate that the in situ formed lithium stearate can decompose at ∼290 °C, which is beneficial for the formation of carbon coating and reduction of Fe³⁺ species, and then the crystallized LiFePO₄/C nanocomposite can be formed at 400 °C without other intermediate products. As cathode material of Li-ion battery, the obtained LiFePO₄/C nanocomposite exhibits a good rate and cycling performance with a high discharge capacity of ∼160 mAh g⁻¹ (>94% theoretical capacity of LiFePO₄) at a current density of 1 C (170 mA g⁻¹), and ∼96% of its initial capacity can be retained after 200 charging/discharging cycles. Even at a high current density (10 C), the LiFePO₄/C nanocomposite still presents a discharge capacity as high as ∼100 mAh g⁻¹. The excellent electrochemical performances of the present LiFePO₄/C nanocomposite mainly originate from the good crystallinity, small particles and enhanced electronic conductivity of the materials coated and linked by carbon layers.