Goldene monolayer as a highly effective catalyst for polysulfide anchoring and conversion: A theoretical study

TL;DR

This theoretical study demonstrates that Goldene, a new two-dimensional gold allotrope, effectively binds lithium polysulfides and facilitates their conversion, making it a promising catalyst for lithium-sulfur batteries.

Contribution

The paper introduces Goldene as a novel 2D gold allotrope that strongly interacts with lithium polysulfides, showing potential as an efficient catalyst for battery applications.

Findings

Strong binding of Li-S species to Goldene with adsorption energies from -4.29 to -1.90 eV.

Charge transfer and hybridization indicate strong electronic coupling at the interface.

Thermodynamically favorable conversion of S8 to Li2S with a low rate-determining barrier of 0.47 eV.

Abstract

We use first-principles density functional theory to investigate how lithium sulfide and polysulfide clusters (Li2S, Li2S2, Li2S4, Li2S6, Li2S8, and S8) bind to Goldene, a new two-dimensional gold allotrope. All Li-S species exhibit robust binding to Goldene. The adsorption energies range from -4.29 to -1.90 eV. S8 that is alone interacts much less strongly. Charge density difference and Bader analyses indicate that substantial charge is transferred to the substrate, with a maximum 0.92 e for Li-rich clusters. This transfer induces polarization at the interface and shifts the work function to 5.30-5.52 eV. Projected density-of-states calculations indicate that Au-d and S-p states strongly mix near the Fermi level. This hybridization indicates that the electronic coupling is strong. Based on these results, the reaction free-energy profile for the stepwise conversion of S8 to Li2S on Goldene is thermodynamically favorable. The overall stabilization is -3.64 eV, and the rate-determining barrier for the Li2S2 -> Li2S step is 0.47 eV. This shows that Goldene is an effective surface for anchoring and mediating lithium polysulfide reactions.