Highly controlled synthesis of multi-shelled NiO hollow microspheres for enhanced lithium storage properties

Nickel oxide microspheres with porous multi-shelled structure were synthesized via a sequential templating approach using carbonaceous microspheres (CMSs) as sacrificial agent. When applied as anode material for lithium ion batteries, the as-prepared porous triple-shelled NiO hollow spheres show excellent cycling performance and outstanding high-rate capability, as well as high specific capacity. During all the 100 discharge-charge cycles under a current density of 500 mA/g, the porous triple-shelled NiO hollow spheres can stably deliver a reversible capacity of ca. 789 mAh/g. Even at a high current density of 2000 mA/g, the specific discharge capacity of the porous triple-shelled NiO hollow spheres is still as high as 721 mAh/g, which is twice larger than that of commercial graphite. The superior electrochemical performance can be attributed to the porous multi-shelled hollow microstructure which guarantees more lithium-storage sites, a shorter lithium-ion diffusion length, and sufficient void space to buffer the volume expansion.