First-Principles Study of Zigzag MoS2 Nanoribbon As a Promising Cathode Material for Rechargeable Mg Batteries

Zigzag MoS2 nanoribbon is a promising cathode of rechargeable magnesium batteries. A first-principles study based on density functional theory (DFT) has been carried out on this material concentrating on key issues relating to magnesium adsorption sites, theoretical capacity, and diffusion kinetics. It is found that the Mo top site at the edge of the nanoribbon is favorable for Mg locations. On zigzag MoS2 nanoribbon, a maximum theoretical capacity of 223.2 mAh g(-1) could be achieved by double-side Mg adsorptions. Electronic calculations suggest that partial charge transfers occur between the adsorbed Mg atoms and zigzag MoS2 nanoribbon, but meanwhile, the covalent hybridizations are still observable. A Mg diffusion pathway on the zigzag MoS2 nanoribbon is identified as passing two adjacent T sites mediated by the nearest neighboring H site in between. The activation barrier of this process is only 0.48 eV, much reduced from the 2.61 eV of the bulk interlayer migration. The present results give expectation of excellent battery performance by the zigzag MoS2 nanoribbons.