A first principle study of structural and electrical properties of novel Li2FeO3/Li2FeO2F Li-ion battery cathode material

Abstract

Li-ion battery cathode materials, namely Li2FeO3 and Li2FeO2F, are investigated using noble evaluation approaches for the electrical properties, assuming that the reacted-unreacted structure interface is acting as a semiconductor junction. The evaluations are done by calculating different methods of density functional theory, and consequently resulted in lattice parameters and their changes, structural properties, and also density of states (DOS) diagrams to assess electrical properties. The approach assigns a value for each evaluated cathode material and provides a semi-quantitative criterion in the matter of rate-capability for having a comparison between the materials. It also considers the configuration of the unreacted-reacted structures with respect to each other and also the electric field direction simultaneously. Results from structural data showed that evaluated cathode materials face a significant amount of cell volume decrease during the delithiation process, thus it is expected that it has a strong impact on their cyclability and lifetime. According to the rate-capability criterion values obtained from the DOS diagrams calculated via GGA+U and GGA, results show that the presence of the Fluorine element inside the structure can improve the rate-capability.