Magnesium Ion Storage Properties in a Layered (NH)VO·1.5HO Nanobelt Cathode Material Activated by Lattice Water.

Magnesium ion batteries have attracted increasing attention as a promising energy storage device due to the high safety, high volumetric capacity, and low cost of Mg. However, the strong Coulombic interactions between Mg ions and cathode materials seriously hinder the electrochemical performance of the batteries. To seek a promising cathode material for magnesium ion batteries, in this work, (NH)VO·1.5HO and water-free (NH)VO materials are synthesized by a one-step hydrothermal method. The effects of NH and lattice water on the Mg storage properties in these kinds of layered cathode materials are investigated by experiments and first-principles calculations. Lattice water is demonstrated to be of vital importance for Mg storage, which not only stabilizes the layered structure of (NH)VO·1.5HO but also promotes the transport kinetics of Mg. Electrochemical experiments of (NH)VO·1.5HO show a specific capacity of 100 mA·h·g with an average discharge voltage of 2.16 V vs Mg/Mg, highlighting the potential of (NH)VO·1.5HO as a high-voltage cathode material for magnesium ion batteries.