Theoretical dopant screening and processing optimization for vanadium disulfide as cathode material for Li-air batteries: A density functional theory study

Abstract

As a strategy to improve the catalytic performances of two-dimensional transition metal dichalcogenide materials, doping and defect engineering are widely used. However, it is extremely challenging to find proper new materials and doping/defect engineering conditions relying only on experimental trial-and-error. In this study, use of vanadium disulfide (VS2) was suggested as an effective cathode catalyst for Li-air batteries (LABs), under the condition of proper doping engineering to optimize electrochemical performances. To investigate the dopant screening and doping processing optimization of VS2, a theoretical concept, which combines first-principles calculations and thermodynamic modeling, was first derived and suggested. Through our approach, it is worth noting that F- and N-doping on H-VS2 shows superior overpotential properties (0.68 V and 0.76 V) than the carbon-based cathode and NH3 and O-2 as reactant for T-VS2, and N-2 and H-2 for H-VS2 are necessary to control the N doping on VS2. Our theoretical work provides the guideline for application of VS2 to cathode of LABs and leads to further insights for designing a new cathode materials based on two-dimensional materials.