Strain effects on the adsorption behavior of PtS2 monolayer as anchoring material for lithium-sulfur batteries: A DFT study

Abstract

The practical implement of lithium-sulfur batteries is significantly impeded by low electronic conductivity of anchoring substrate and the shuttle effect. To address these issues, we employed density functional theory (DFT) to investigate the behavior of lithium polysulfides (LiPSs) adsorbed on PtS2 monolayers in lithium-sulfur batteries. The results demonstrate a moderate binding strength between PtS2 monolayers and LiPSs, effectively suppressing the shuttle effect. Furthermore, the bandgap of PtS2 monolayers decreased remarkably during the lithiation, accompanied with semiconductor-metal transition, leading to a significant improvement in conductivity. The diffusion barriers and decomposition barrier of the adsorbed of Li2S clusters on PtS2 monolayer were calculated to assess the delithiation reaction kinetics. These values are comparable to those observed in other two-dimension (2D) materials, indicating the potential for rapid charge/discharge in Li-S batteries. Especially we considered the impact of strain arise from volume expansion on binding energy and diffusion processes. Our results indicate that under strain, the PtS2 substrate can still effectively anchor LiPSs while facilitating their diffusion. Through a series of calculations, we can conclude that the PtS2 monolayer holds promise as the anchoring material for Li–S batteries.