Surface Electrostatic Potential Roughness: A Crucial Factor Impacting Lithium Diffusion on Curved Transition Metal Dichalcogenide Surfaces

Abstract

Tuning the nanoscale morphology and structure is a key strategy for enhancing the electrostatic performance of layered transition metal dichalcogenide (TMD) electrodes, where curved structures are inevitably introduced. A comprehensive understanding of the Li-ion diffusion mechanism in curved TMD structures at the atomic scale can guide the high-throughput design of nanoscale electrode materials. By first-principles calculations, we investigated the lithium diffusion in TMDs curved structure and factors resulting in the diffusion barrier variation. Our results demonstrate that the curved structure of TMDs enhances lithium diffusion compared to the planar structure, with the effect of bending on lithium diffusion being influenced by multiple factors. By extracting and analyzing the surface electrostatic potential curve perpendicular to the lithium diffusion path, we introduced the R_Δq/L parameter to provide a unified explanation for the effect of bending on lithium diffusion, where R_Δq represents the roughness of the curve and L represents the projected length of the curve. For the same TMDs with varying curvature, the R_Δq/L perpendicular to the diffusion path is positively correlated with the lithium diffusion barrier on this path. Our results deepen the understanding of the lithium diffusion mechanism for the TMD curved structure and promote the follow-up design of TMD-based electrodes.