Synthesis of the Stoichiometrical LixLi′1-xNa0.06MnO2 Containing Li2MnO3 Phase by Ion-Exchange Method

Using ion-exchange method , previous researchers have successfully synthesized cathode materials with excellent electrochemical properties. In this paper, the stoichiometrical LixLi ' 1-xNa0.06MnO2 containing Li2MnO3 phase was synthesized depending on the two stages which was the characteristic of the ion-exchange route. The additive proportion of Li in the first and second steps of the ion exchange process was changed in the purpose of regulating the proportional relation of the layered Li gamma Na0.06MnO2 and the monoclinic Li2MnO3 (m- Li2MnO3 ) phases. The Li lambda Li1-xNa0.06MnO2 cathode material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and galvanostatic charge-discharge cycling technique in order to investigate the crystalline structure, surface morphology and electrochemical property. Through our experiments, Li0.25Li'0.75Na0.06MnO2 and Li0.35Li'0.65Na0.06MnO2 behaved the excellent electrochemical performance. Li0.25Li'0.75Na0.06MnO2 could deliver the capacity of 206 mAhg(-1) at 10 mAg(-1) in the first charge process, and Li0.35Li'0.65Na0.06MnO2 showed outstanding cycle stability. Its average discharge specific capacity reached 150 mAhg(-1). The improved performance might arise from the existence of the optimal proportion of m- Li2MnO3 phase . This stoichiometrical LixLi1-xNa0.06MnO2 might be a good substitute for the cathodes containing poisonous or expensive metals.