Novel synthesis and electrochemical behavior of layered LiNi0.5Mn0.5O2

A novel and simple solid state synthesis of layered LiNi0.5Mn0.5O2 directly from a mixture of LiOH, NiO and MnO2 prepared by ball milling is reported. The mixtures of precursors were heated at temperatures from 400 to 1000 °C in air to synthesize the compound. The heat treatment process and the crystal structure of the synthesized material were investigated by TG/DTA and X-ray diffraction (XRD) methods. The well-crystallized LiNi0.5Mn0.5O2 powder of single phase was prepared at 1000 °C. Morphology of the synthesized material was investigated using field emission scanning electron microscopy (FESEM). X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) measurements were carried out on the synthesized LiNi0.5Mn0.5O2 powder suggesting that the oxidation states of Ni and Mn in LiNi0.5Mn0.5O2 be +2 and +4, respectively. Galvanostatic charge–discharge behavior of the Li/LiNi0.5Mn0.5O2 cell in the voltage range 2.5–4.3 V at a current rate of 0.1 mA cm−2 exhibited a stable discharge capacity of ∼120 mAh g−1 with a very small capacity fading for 10 cycles.