  We have investigated the lithium capacity of the 2H phase of niobium sulphide
(NbS2) 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 NbS2 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 NbS2-based anodes find a first
specific capacity of about 1,130 mAh/g, exceeding the theoretical predictions.
