Improvement of electrochemical properties of LiNi 0.5Mn 1.5O 4 spinel prepared by radiated polymer gel method

Abstract

LiNi 0.5Mn 1.5O 4 as a 4.7 V-class cathode material was prepared through the radiated polymer gel method that allowed homogeneous mixing of starting materials at the atomic scale. After calcinations of the polymer gels containing the metal salts at different temperatures from 750 to 1150 °C, powders of a pure LiNi 0.5Mn 1.5O 4 phase were obtained. X-ray diffraction and transmission electron microscopy were used to characterize the structures of the powders. Galvanostatic cell cycling and a simultaneous DC resistance measurement were performed on Li/LiNi 0.5Mn 1.5O 4 cells. It is found that the powder calcined at 950 °C shows the best electrochemical performance with the initial discharge capacity of 139 mAh g −1 and 96% retention after 50 cycles. Adopting a slow cooling procedure for the powder calcination can increase the capacity of LiNi 0.5Mn 1.5O 4 at the 4.7 V plateau. Besides, a “w”-shape change of the DC resistance of Li/LiNi 0.5Mn 1.5O 4 cells is a good indication of the structural change of LiNi 0.5Mn 1.5O 4 electrode during charge and discharge courses.