Tailoring the Growth and Morphology of Lithium Peroxide: Nickel Sulfide/Nickel Phosphate Nanotubes with Optimized Electronic Structure for Lithium-Oxygen Batteries.

ABSTRACT

Heterogeneous crystalline-amorphous structures, with tunable electronic structures and morphology, hold immense promise as catalysts for lithium-oxygen batteries (LOBs). Herein, a nanotube network constructed by crystalline nickel sulfide/amorphous nickel phosphate (NiS/NiPO) heterostructure is prepared on Ni foam through the sulfurization of the precursor generated hydrothermally. Used as cathodes, the NiS/NiPO nanotubes with optimized electronic structure can induce the deposition of the highly porous and interconnected structure of Li2 O2 with rich Li2 O2 -electrolyte interfaces. Abundant active sites can be created on NiS/NiPO through the charge redistribution for the uniform nucleation and growth of Li2 O2 . Moreover, nanotube networks endow cathodes with efficient transport channels and sufficient space for the accommodation of Li2 O2 . A high discharge capacity of 27 003.6 mAh g-1 and a low charge overpotential of 0.58 V at 1000 mAh g-1 can be achieved at 200 mA g-1 . This work provides valuable insight into the unique role of the electronic structure and morphology of catalysts in the formation mechanisms of Li2 O2 and the performances of LOBs.