Theoretical study of catalytic performance of X-γ-Graphyne as cathodes for lithium-air batteries

Abstract

Lithium-air batteries (LiO₂) are considered one of the most promising energy storage and conversion device candidates for future mobility applications, such as electric vehicles, due to their ultrahigh theoretical energy density (up to ∼3600 Wh kg^‐1). The main goal in this work is to study an electrochemical catalytic model for a cathode in LiO₂ batteries to simulate the OER during the discharging process. Density Functional Theory (DFT) calculations were performed to investigate γ-Graphyne and N-γ-Graphyne (N-Doped γ-Graphyne) as the potential cathode catalyst for LiO₂ batteries. γ-Graphyne and N-γ-Graphyne surfaces exhibit high stability according to calculations, the pristine surface exhibits a slight improvement in the formation energy of Li_xO₂, moreover, the N-Doped surface can reduce the significant formation energy of Li_xO₂ in the OER. Calculations explain the catalytic mechanism and identify the active sites to perform N-doping on pristine γ-Graphyne. This study demonstrates a feasible approach to achieve designed γ-Graphyne and N-γ-Graphyne as cathode catalysts for Li air batteries, which is promising for cost reduction in mass production of Li-air batteries.