Multi-shelled NiO hollow spheres: Easy hydrothermal synthesis and lithium storage performances

Complex metal oxide hollow structures are mostly prepared by hard template-based multistep procedures. It is still desirable yet challenging to develop new efficient strategies to fabricate high-quality complex metal oxide hollow structures. Herein, uniform multi-shelled NiO hollow spheres were synthesized; especially quintuple-shelled NiO hollow spheres were synthesized for the first time by a simple shell-by-shell self-assembly capable of controlling the shell numbers, which are achieved by controlling the heat treatment. The research makes a significant contribution to the synthetic methodology of multi-shelled hollow structures and opens up new opportunities for deeper understanding formation mechanism of the shell-by-shell self-assembly. The obtained quadruple/quintuple-shelled NiO hollow spheres show promising electrochemical performance in anodic lithium storage for Li-ion battery.