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 energy storage technologies due to their extremely high theoretical energy density. However, low catalytic efficiency of the cathode 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 quantum confinement effect induces Mo6S6 and Mo6Se6 nanowires to exhibit metallic properties and high electronic conductivity. Furthermore, Mo6S6 nanowire exhibits the lowest overpotentials for ORR and OER, demonstrating excellent electrochemical performance. Meanwhile, we considered the solvent effect and found that Mo6X6 exhibits excellent structural stability in both DMSO and TEGDME without causing decomposition of the solvent molecules. More interestingly, 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. 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.