Effects of Zn doping amount on the electrochemical properties of LiNi0.5Mn1.5O4 lithium ion cathode materials

Abstract

The effects of Zn doping for Mn site on the electrochemical properties of LiNi0.5Mn1.5-xZnxO4 (x=0, 0.01, 0.03, 0.05, 0.08, 0.10) have been systematically investigated. The LiNi0.5Mn1.5xZnxO4 samples, which were synthesized by a modified low temperature solution combustion synthesis method, were characterized by X ray diffraction(XRD), infrared s pectroscopy(FT IR), scanning electron microscopy(SEM), galvanostatic charge discharge testing, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). All samples have perfect cubic spinel structures with a combination of ordered and disord ered space groups. The microstructure is almost not affected by the amount of Zn doping obtained from the SEM results. The electrochemical performances are obviously improved by Zn doping, which are shown from cycle stability, rate capability and high temp erature cycling performance. The cycle performance is promoted with the increasing of Zn doping content both at 25 °C and at elevated temperature of 55 °C The first charge discharge efficiency and rate capability first increase and then decrease with the increase of Zn doping content, which is best when the Zn doping content is 0.05. Meanwhile, the impedance of products significantly decreases after Zn doping.