Li1.03Mn1.97O4 spinel material was coated with a thin layer of SiO2 by a sol-gel method. The surface modification was found to reduce the Mn2+ dissolution into the electrolyte according to the inductively coupled plasma (ICP) analysis results and improve the capacity retention of the Li1.03Mn1.97O4 spinel. The structure and properties of the coating materials were also investigated by X-ray photoelectron spectra (XPS) analysis, X-ray diffraction (XRD) patterns and Transmission electron microscope (TEM).