Lithium cobalt oxide (LiCoO2) and Lithium nickel oxide (LiNiO2) as the lithium metal layered oxides have been drawing much attention as cathode materials for advanced rechargeable thin film lithium batteries. These lithium metal layered oxides are macro-porous materials with specific crystallography structures.LiCoO2 and LiNiO2are rock salt-structured materials based on a close-packed network of oxygen atoms with Li+ and Ni3+ or Co3+ions which are located at the octahedral interstices with the alternating (111) planes. This (111) ordering introduces a slight distortion of the lattice to hexagonal symmetry; thus, the structure of these materialscan not been determined carefully.For optimizing the propertiesof these layered oxide cathode materials, it is importantto understand the crystallographic geometry of these materials in molecular scale.In this study,the molecular geometry and vibrational frequencies of two different kinds of cathode materials -LiCoO2 and LiNiO2-have been investigated using computational method. Density function theory (DFT)method has been performed to achieve this goal. Calculated results can predict the optimized geometric bond lengths and bond angles of the samples which are in agreement with those single crystal X-ray diffraction experiments. In addition, calculated Infrared (IR) and Raman spectroscopy results are in agreement with those experimental data.

Keywords