Enhanced electrochemical performance of carbon nanospheres–LiFePO4 composite by PEG based sol–gel synthesis

The carbon nanospheres–LiFePO4 (CNSs–LiFePO4) composite has been synthesized by PEG (polyethylene glycol, mean molecular weight of 30,000) based sol–gel route. Highly conductive CNSs (30–40 nm) were adopted to improve the electronic conductivity of LiFePO4. PEG was used to promote the dispersion of CNSs with the surface functionalization of CNSs, which could facilitate the coating of CNSs on the surface of the LiFePO4 particles. The sample was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and Raman scattering. Electrochemical performance of the CNSs–LiFePO4 composite was characterized by the charge–discharge test and electrochemical impedance spectra measurement. The results indicated that LiFePO4 particles were well coated with the conductive CNSs to overcome the intrinsic low electronic conductivity problem of LiFePO4. The CNSs–LiFePO4 composite delivered an enhanced rate capability (146, 128 and 113 mAh g−1 at 0.1 C, 1 C and 5 C rate). The PEG based sol–gel route enables LiFePO4 networked with CNSs, which offered a higher electrochemical performance.