LAUSR

Abstract The structural collapse of transition metal sulfides in repeated charge and discharge process restricts their cyclic performance. How to effectively remedy stability without sacrifice of capacity still remains a daunting challenge. Herein, ultra-small NiS2 quantum dots (QDs) are assembled with pyridine ligands containing heterocyclic nitrogen atoms of high electronegativity. The induction of electron cloud of heterocyclic nitrogen shortens the Ni S bond with stronger structural stability. Besides, the localized lone pair of electrons near nickel atoms reduces the repulsive force to the diffused OH− ions, thus increasing affinity of the redox reaction. Benefiting from the tailor-made of ligands and size effect of QDs, a great promotion in both specific capacity of 651.8 C∙g−1 at 1 A∙g−1 and stability of 94.7% retention at 5 A∙g−1 over 8000 cycles is achieved as compared to ordinary bulk materials. These results demonstrate that ligands induced QDs is a promising strategy for precisely regulating metal sulfide electrode materials of advanced energy storage devices.