Electrochemical and Structural Investigations on ZnO Treated 0.5 Li₂MnO₃-0.5LiMn_0.5Ni_0.5O₂Layered Composite Cathode Material for Lithium Ion Battery

Abstract

0.5Li2MnO3-0.5LiMn0.5Ni0.5O2 composite cathode material with and without ZnO treatment has been synthesized using carbonate based co-precipitation method for rechargeable lithium ion battery. The X-ray diffraction study confirms that the material has layered LiNi0.5Mn0.5O2 structure along with the formation of the superlattice ordering of Li2MnO3; without any major change in the crystal structure with ZnO treatment. Raman spectroscopy has revealed two different types of ionic arrangements corresponding to space groups of C2/m and Rm for Li2MnO3 and LiNi0.5Mn0.5O2 respectively. Morphological studies revealed primary particles are of ∼1 micron size and have sharp, elongated edges. The particles are present as spherical agglomerates (∼10 micron). Elemental mapping and X-ray photoelectron spectroscopy confirmed the presence of Zn in the ZnO treated samples. Charge/discharge capacity of the composite cathode materials (with and without ZnO coating) increases with number of cycles due to more and more activation of the Li2MnO3. However, ZnO treated 0.5Li2MnO3-0.5LiMn0.5Ni0.5O2 composite material showed higher charge/discharge capacites attaining saturation in less number of cycles. Lower resistance to charge transfer in the case of ZnO treated sample is responsible for its better performance.