High Capacity NbS-Based Anodes for Li-Ion Batteries.

We have investigated the lithium capacity of the 2 phase of niobium sulfide (NbS) using density functional theory calculations and experiments. Theoretically, this material is found to allow the intercalation of a double layer of Li in between each NbS layer when in equilibrium with metal Li. The resulting specific capacity (340.8 mAh/g for the pristine material, 681.6 mAh/g for oxidized material) can reach more than double the specific capacity of graphite anodes. The presence of various defects leads to an even higher capacity with a partially reversible conversion of the material, indicating that the performance of the anodes is robust with respect to the presence of defects. Experiments in battery prototypes with NbS-based anodes find a first specific capacity of about 1,130 mAh/g, exceeding the theoretical predictions.