Structural and electronic properties of fluorine-doped lithium oxide as a solid electrolyte interphase for lithium air batteries

Abstract

In Lithium-Air Batteries (LABs), the solid electrolyte interphase (SEI) layer plays a crucial role as a protective barrier and regulates the transport of lithium ions, preventing deterioration of the electrode and electrolyte during undesired reactions. The SEI layer acts as a barrier between the lithium anode and electrolyte, enhancing the stability and efficiency of LABs during charge/discharge cycles. In this study, the effectiveness of a composite SEI layer consisting of Li_2 O and LiF was investigated. The dynamical stability of this configuration was verified using Density Functional Theory and analysis of the phonon spectrum. The analysis of the electronic properties of the structure revealed a noteworthy decrease in the band gap. This decrease in the band gap is particularly significant as it contributes to the improved performance of lithium-air batteries. Furthermore, additional investigations were conducted to examine the effects of doping other halogen atoms and increasing the concentration of fluorine. However, these results revealed that the electronegativity differences between the atoms rendered such structures unstable, posing challenges in achieving stable configurations for practical applications.