Surface phase composition of nanosized LiFePO4 and their enhanced electrochemical properties

Despite the great achievement in understanding the materials properties of LiFePO4, the surface phase composition of nanosized LiFePO4 has been almost ignored. The present study reports the synthesis of nanosized core-shell LiFePO4 with size of about 50 nm by one step solvothermal route using Polyethylene glycol 600 as solvent. The structural characterization of the surface of nanosized core-shell LiFePO4 particles has been investigated using soft X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. The nanosized LiFePO4 is well-covered by an amorphous LiFeP2O7 layer containing trace carbon. Density functional theory (DFT) calculation is used to illustrate the origin of amorphous LiFeP2O7 layer. The nanosized core-shell LiFePO4 exhibits excellent charge transfer kinetics and charge/discharge performance. These new investigations shed new insight into the surface phase composition of nano-particles. The synthesis of the nanosized core-shell LiFePO4 paves an effective way to develop cathode materials with high rate capabilities for use in Li-ion batteries.