Theoretical design of graphene/tungsten dichalcogenide (Gr/WX2, X=S, Se) heterostructures used for anode materials of LIBs from DFT calculations

Abstract

2D van der Waals heterostructures are highly promising for Lithium-ion batteries (LIBs), offering excellent energy capacity and extended lifespan when used as anodes. In this study, we systematically investigate the geometrical structures and electronic properties of graphene/tungsten dichalcogenide (Gr/WX2, X=S, Se) heterostructures, focusing on lithium (Li) atom adsorption and movement in these materials using first-principles calculations through density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. Our results reveal that the Gr/WX2 heterostructures possess excellent structural stability, with mechanical strength validated by their elastic constants. The diffusion barriers of Li atoms in Gr/WS2 and Gr/WSe2 heterostructures are competitive compared with other anode materials. Additionally, the Li diffusion coefficients at 300 K for Gr/WS2 and Gr/WSe2 are also surpassing those observed in pristine Gr. Furthermore, Gr effectively lowers the average open-circuit voltage (OCV) of Gr/WX2 heterostructures to optimal levels, with Gr/WS2 at 0.29V and Gr/WSe2 at 0.25V. The Gr/WS2 and Gr/WSe2 heterostructures after adsorption of Li exhibit remarkable thermal stability at 300K, maintaining their structural integrity throughout the simulation period. Our research provides comprehensive theoretical guidance for the practical development and application of Gr/WX2 heterostructures as anode materials in LIBs.