Low temperature synthesis of nanostructured LiFePO4/C cathode material for lithium ion batteries

Abstract

Nanostructured olivine LiFePO4 was successfully synthesized by mechanical activation of powder obtained by co-precipitation. The effects of mechanical activation energy, calcination temperature and carbon coating on the LiFePO4 characteristics were investigated. X-ray diffraction results revealed that mechanical activation has facilitated the formation of pure, fully crystallized and nano-structured LiFePO4. Scanning electron microscope observations showed that the average particle size of LiFePO4 powder is approximately 70 nm. Fourier transform infrared spectra analysis revealed the existence of no extra peak in the carbon coated LiFePO4 samples compared to the pure one. Raman spectra demonstrated high quality of the obtained carbon layer with sp2/sp3 ratio of about 0.9 which proves the existence of highly conductive graphite like carbon in the cathode materials. Electrochemical analyses showed superior properties in the fields of capacity (163 mA h g−1 at 0.1C), rate capability, and battery stability over 50 cycles for mechanically activated LiFePO4/C cathode materials.