Mo6x6 Nanowires Enhance the Catalytic and Cycling Performance of Non-Aqueous Li-O2 Batteries

Abstract

Lithium-air batteries are considered one of the most promising electrochemical energy storage technologies due to their extremely high theoretical energy density. However, the low catalytic efficiency of the anode catalyst limits its practical application. Here, we systematically studied the ORR/OER performance of Mo6X6 (X=S, Se, Te) nanowires as cathode catalysts for Li-O2 batteries using first-principles calculations. The results indicate that the quantum confinement effect induces Mo6S6 and Mo6Se6 nanowires to exhibit metallic properties and high electronic conductivity. Meanwhile, the high specific surface area of the nanowires provides a large deposition site for the discharge products, resulting in good ORR/OER performance of lithium-air batteries. Molecular dynamics simulations show that the surface of Mo6S6-NWs is more prone to the formation of an amorphous Li2O2 film, which can significantly reduce the interface contact resistance. This leads to rapid decomposition of the film-like Li2O2 and results in lower overpotential and good cycling performance. The nudged elastic band (NEB) calculation indicates that O2 has difficulty displacing the non-metallic elements in Mo6X6 nanowires, demonstrating their excellent structural stability. Our work provides important references for efficiently screening and developing cathode catalysts for Li-O2 batteries.

Keywords: Li-O2 Batteries, Mo6X6 nanowires, Density-functional theory, ORR/OER, Film-like Li2O2