Strain-engineered two-dimensional MoS2 as anode material for performance enhancement of Li/Na-ion batteries

Abstract

Recent years have witnessed a surge of research in two-dimensional (2D) nanostructures for development of new rechargeable Li/Na-ion battery systems. Herein, via first-principles calculations we demonstrate strain-engineered Li/Na adsorption and storage in 2D MoS2 as anode material, aiming to enhance the operating performance of Li/Na-ion batteries. Our results show that tensile strain greatly increases the adsorption of Li/Na atoms on MoS2, and a modest strain of 6% increases Li (Na) adsorption energy by over 70%, which originates from the strain-induced upshift of Mo d states towards Fermi level that interact strongly with Li/Na s states, in analogy with the d-band model in metal catalyst. Significant narrowing of the n-doped semiconducting gap of MoS2 suggests the improved electric conductivity that may benefit charge carrier transport. By mapping out the potential energy surfaces, we show shallow energy barriers of ion diffusion with ~0.2 eV for Li and 0.1 eV for Na. Furthermore, the strain-steered competition between chemical bonding and coulomb repulsion results in high Li/Na storage capability and relatively low average operating voltage. We believe that the fundamental principle underlying the use of strain to enhance performance of renewable ion battery is applicable to other stretchable low-dimensional nanomaterials.

Metal-Ions Intercalation Mechanism in Layered Anode From First-Principles Calculation

“…In Figures 4A,B , the band gap of MoS 2 was seen to vanish during the adsorption of Li and Na-ions in contrast to the existence of the band gap in the adsorption of Mg and Zn-ions on MoS 2 . For comparison, the DOS of pure MoS 2 had be repeated ( Figure 5 ), which was in accordance with the reported previously (Hao et al, 2018 ; Chen et al, 2020 ). These results indicated that the semiconductor MoS 2 may be transformed into metal during the insertion of Li and Na ions, while the properties of the MoS 2 semiconductor remained unchanged during the insertion of Mg and Zn ions ( Figure 4D ), resulting in low electronic conductivity in divalent-ions batteries.…”

2D Square Octagonal Molybdenum Disulfide: An Effective Anode Material for LIB/SIB Applications

“…It is noted that the adsorption energies on the surface of so‐MoS 2 are significantly higher in comparison to the h‐MoS 2 surface that makes so‐MoS 2 potentially better for application as anodes in LIBs/SIBs. [ 60,61 ] The stronger adsorption energies lead to a rapid loading process with an exothermic reaction between Li/Na and so‐MoS 2 .…”

Lattice-distorted lithiation behavior of a square phase Janus MoSSe monolayer for electrode applications

“…In the extreme case of interlayer expansion, some 2D materials, including graphene and MoS 2 , become thermodynamically unstable upon Li adsorption, resulting in the irreversible formation of Li metal clusters. [17][18][19] To overcome such a limitation, surface defects in 2D layers have been demonstrated as an effective way to enhance the thermodynamic stability of both graphene and TMD monolayers, contributed by increased charge transfer. [20][21][22][23] Unfortunately, such a defect engineering method is highly limited by its uncontrollable synthesis procedure and undesired mechanical failure upon lithiation.…”