Lithium Intercalation in Graphene/MoS2 Composites: First-Principles Insights

TL;DR

This study uses first-principles calculations to explore lithium intercalation in graphene/MoS2 composites, revealing insights into storage capacity, band gap tuning, and electronic structure preservation.

Contribution

It provides the first theoretical analysis of Li intercalation in Gr/MoS2 using van-der-Waals-corrected DFT, highlighting mechanisms behind storage capacity and electronic property changes.

Findings

Li binding energies increase with more intercalated Li atoms.

Band gap of graphene enlarges with more Li, up to 160 meV.

Dirac cone of graphene remains intact despite Li intercalation.

Abstract

As a storage material for Li-ion batteries, graphene/molybdenum disulfide (Gr/MoS2) composites have been intensively studied in experiments. But the relevant theoretical works from first-principles are lacking. In the current work, van-der-Waals-corrected density functional theory calculations are performed to investigate the interaction of Li in Gr/MoS2 composites. Three interesting features are revealed for the intercalated Gr/Li(n)/MoS2 composites (n = 1 to 9). One is the reason for large Li storage capacity of Gr/MoS2: due to the binding energies per Li atom increase with the increasing number of intercalated Li atoms. Secondly, the band gap opening of Gr is found, and the band gap is enlarged with the increasing number of intercalated Li atoms, up to 160 meV with nine Li; hence these results suggest an efficient way to tune the band gap of graphene. Thirdly, the Dirac cone of Gr always preserve for different number of ionic bonded Li atoms.