In situ coating on LiFePO4 with ionic liquid as carbon source for high-performance lithium batteries

LiFePO4/C materials were synthesized via an in situ coating on LiFePO4 with 1-butyl-3-methylimidazolium dicyanamide [BMIm][N(CN)(2)] as a carbon source. The electrode materials were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results revealed that 1-2 nm carbon films were successfully coated on the LiFePO4 particles. The electrochemical properties of LiFePO4/C composite were investigated by cyclic voltammetry (CV) curves, electrochemical impedance spectra (EIS), and electrochemical analysis. The test results showed that the LiFePO4/C composite possessed outstanding reversibility, cycle performance, and rate performance. The discharge capacities of LiFePO4/C were 161.5 mAh g(-1) at 0.1 C and 143.6 mAh g(-1) at 1 C, respectively. The excellent electrochemical properties of the LiFePO4/C electrode were mainly due to the thin, uniform, and highly graphitized carbon films.