Comparison Electrochemical Performances of Spherical LiFePO4/C Cathode Materials at Low and High Temperatures

Abstract

The spherical LiFePO4/C composite material was prepared by the solid-state method and a spray dry method. The surface modification was conducted on spherical LFP/C composite by using 3wt.% Li4Ti5O12 (LTO) to improve the rate capability and cycle stability properties at a low temperature of -20oC and a high temperature of 55oC. The characteristic properties were examined by X-ray diffraction (XRD), micro-Raman, scanning electron microscopy (SEM), AC impedance method, and galvanostatic charge-discharge method. For comparison, the as-prepared LiFePO4/C cathode, SP LFP/C composite, and 3%LTO-modified spherical LiFePO4/C composite are studied and compared. As a result, the LTO-modified spherical LiFePO4/C composite displays the discharge capacities of 150, 145, 135, 110, 95 and 90 mAh g-1 at 0.1C, 0.2C, 0.5C, 1C, 3C and 5C rates, respectively. It is demonstrated that the LTO-modified spherical LiFePO4/C composite material exhibit a good candidate for application in Li ion batteries.