Ab initio characterization of layered MoS2 as anode for sodium-ion batteries

Abstract Identifying suitable layered materials as electrodes with desirable electrochemical properties remains a key challenge for rechargeable Na-ion batteries (NIBs). Using first principles methods, here we examine the efficacy of layered molybdenum disulphide (MoS 2 ) as a host electrode material for NIBs. We identify various low energy Na adsorption sites and evaluate the stability of the hexagonal and tetragonal polytypes of MoS 2 upon Na intercalation. Our results illustrate a moderately strong binding between Na and MoS 2 that is thermodynamically favorable against the cluster formation and phase separation of Na. We find that while Na intercalation in MoS 2 results in a phase transformation from the hexagonal phase to the tetragonal phase, it gives rise to a maximum theoretical capacity of 146 mAh g −1 and a low average electrode potential in the range of 0.75–1.25 V. Our calculations of Na diffusion kinetics indicates a moderately fast mobility of Na in the van der Waals interlayer spaces of MoS 2 . These results highlight the promise of MoS 2 as an appealing negative electrode (anode) for rechargeable NIBs.