Structural properties of P2 and O2-type layered lithium manganese oxides as potential coating materials

Abstract

Surface coatings have been reported to improve the performance of cathode materials by altering the surface chemistry or providing a physical protective layer. There is currently a challenge of obtaining the most suitable coating materials between the O2 and P2 type structure for coating the O3-type cathode material to mitigate the structural degradation that occurs during cycling. The density functional theory was used to investigate the structural and electronic properties of these materials in a quest to monitor their stability upon their usage as coating materials for O3-Li2MnO3. The partial density of states of the O2 and P2 bulk materials and O2 and P2 materials with vacancies indicated that the electron contribution at the fermi level was due to the p state of oxygen and the d state of manganese. Furthermore, the electronic band structures showed that the materials are metallic, with a band gap of zero. The P2 and O2-type cathode materials have been known to offer high energy density and excellent cycling stability while the P2 has been found to not only enhance the reversibility and air/thermal stability of other cathodes but also improve their electrochemical kinetics and reduce the charge transfer resistance.