First-Principles Investigation of Magnesium Ion Adsorptions and Diffusions on 1H-Monolayer MoS₂ for Energy Storages

Abstract

Effective energy storage and conversion technologies are indispensable for developing advanced rechargeable batteries. Rechargeable Mg batteries have attracted increasing research interest as potential alternative to lithium-ion batteries, due to high energy capability, earth abundant, good operational safety, environmental friendliness, and low cost. Since monolayer MoS₂ have been synthesized through various methods, MoS₂ nanostructures have been applied to enhance the energy storage in the alkali-ion batteries. However, few works focus on the theoretical investigation of the Mg-ion batteries based on 1H-MoS₂ monolayer. In this paper, we conducted the first-principles calculations to investigate the Mg ions adsorption on and diffusion through the 1H-MoS₂ monolayer. Three adsorption sites, including top of S atom, top of Mo atom, and hole site (centre of hexagonal lattice), were considered for measuring the binding energy of Mg-ions. Result show that the binding energy at the top of Mo atom is the larger than those at the other adsorption sites, which indicates the possibly stable absorption configuration. Energy barriers of Mg-ions passing through and diffusing over the MoS₂ monolayer are also calculated. It was found that the Mg-ion has a largest energy barrier to pass through the 1H-MoS₂ layer and a smallest energy barrier to diffuse above the 1H-MoS₂ layer. The band structures and density of states of MoS₂ before and after Mg-ion absorption were also calculated and discussed.