Low-temperature Synthesis of Nanocrystalline LiNi0.5Mn1.5O4 and its Application as Cathode Material in High-power Li-ion Batteries

Abstract

Nickel-doped lithium manganate spinels are a potential material for future energy storage owing to high cell potential and low price. Phase-pure spinels are difficult to prepare by conventional solid-state synthesis methods owing to loss of oxygen from the crystal lattice at high temperature (,8008C). Loss of oxygen causes Jahn-Teller distortion and Mn 4þ is converted into Mn 3þ , which results in undesired double-plateau discharge and reduction in capacity and stability of the material. In this study, nanocrystalline phase-pure LiNi 0.5 Mn 1.5 O 4 was prepared by co-precipitation with cyclohexylamine followed by calcination at a low temperature of 5008C. X-ray diffraction studies confirmed that a highly crystalline face-centred cubic product is formed with F-d3m space group. Scanning electron microscopy and transmission electron microscope studies confirmed that the particles are in the nano range with a porous structure. The as-prepared LiNi 0.5 Mn 1.5 O 4 showed a high initial specific capacity (up to 130 mA h g À1 ) and retained up to 120 mA h g À1 up to 50 cycles. The material has high conductivity and remains stable up to a 20-C discharge rate.