Low-temperature solution combustion synthesis of high performance LiNi0.5Mn1.5O4

Abstract

High-voltage LiNi0.5Mn1.5O4 spinels were synthesized by a low temperature solution combustion method at 400°C, 600°C and 800°C for 3h. The phase composition, structural disordering, micro-morphologies and electrochemical properties of the products were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and constant current charge–discharge test. XRD analysis indicated that single phase LiNi0.5Mn1.5O4 powders with disordered Fd-3m structures were obtained by the method at 400°C, 600°C and 800°C. The crystallinity increased with increasing preparation temperatures. XRD and FTIR data indicated that the degree of structural disordering in the product prepared at 800°C was the largest and in the product prepared at 600°C was the least. SEM investigation demonstrated that the particle size and the crystal perfection of the products were increased with increasing temperatures. The particles of the product prepared at 600°C with ~200nm in size are well developed and homogeneously distributed. Charge/discharge curves and cycling performance tests at different current density indicated that the product prepared at 600°C had the largest specific capacity and the best cycling performance, due to its high purity, high crystallinity, small particle size as well as moderate amount of Mn3+ ions.