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Ab initio study of graphene-like monolayer molybdenum disulfide as a promising anode material for rechargeable sodium ion batteries

Using first-principles study based on density functional theory (DFT), the adsorption sites, diffusion kinetics, theoretical capacity and average voltage of Na atoms in graphene-like monolayer MoS2 are systematically investigated in comparison with bulk MoS2. It is found that for the graphene-like monolayer MoS2, a maximum theoretical capacity of 335 mA h g−1 could be achieved by double-side Na adsorption. Upon sodiation process, the graphene-like monolayer MoS2 can maintain a low voltage platform at about 1.0 V. A Na diffusion pathway on the graphene-like monolayer MoS2 is identified as from two adjacent T-sites passing through the nearest-neighbor H site in a zigzag manner. The activation barrier of this process is only 0.11 eV, a considerable decrease compared to that of the bulk MoS2 interlayer migration (0.70 eV), which indicates that Na can diffuse faster in the graphene-like monolayer MoS2 than in bulk MoS2. The present results suggest that the graphene-like monolayer MoS2 can provide excellent battery performance as the anode material of a sodium ion battery.