Importance of Ignition Temperature in Solution Combustion Synthesis of LiNi0.5Mn1.5O4

Abstract

Solution combustion synthesis method is a simple, direct and effective method to prepare metallic oxides, including the high-voltage LiNi0.5Mn1.5O4 spinels. However, little literature is available on the influence of ignition temperature on the LiNi0.5Mn1.5O4 spinels prepared by solution combustion synthesis. This paper presents the influence of ignition temperature on the phase composition, structural ordering, amount of Mn3+, micro morphology and electrochemical performance of the as-prepared LiNi0.5Mn1.5O4 spinels. X-ray diffraction (XRD), Fourier transform infrared pectroscopy (FTIR), scanning electron microscope (SEM) and charge-discharge measurements in lithium cells have been used to investigate the products. XRD, FT-IR and SEM results indicate that the degree of structural ordering, the amount of Mn3+ and the crystal sharp and size are strongly affected by the ignition temperatures. All the products prepared at different ignition temperatures are more disordered LiNi0.5Mn1.5O4-δ with Fd3m space group. The amount of Mn3+ and the degree of structural disordering in the product with the ignition temperature of 800°C are the largest, and in the product with the ignition temperature of 600°C are the smallest. The crystallinity and grain sizes of the products are increased with increasing ignition temperatures. Electrochemical performances including cycling stability and rate capability of the products are enhanced with increasing ignition temperatures. The product with the ignition temperature of 800°C exhibits excellent cycling stability and rate capability due to its high crystallinity and an appropriate amount of Mn3+ ions.