Scalable Synthesis of Urchin- and Flowerlike Hierarchical NiO Microspheres and Their Electrochemical Property for Lithium Storage

A nickel salt–urea–H₂O ternary system has been developed for the large-scale synthesis of hierarchical α-Ni­(OH)₂ microspheres, the solid precursor for the subsequent topotactic transition to NiO upon calcination. In this facile synthetic system, hierarchical structure is self-assembled under the cooperative direction of urea and anions in nickel salts. Thus, simply tuning the Ni salts leads to the selective construction of urchin and flowerlike hierarchical α-Ni­(OH)₂ and NiO microspheres consisting of radial 1D nanowires and 2D nanoplates, respectively. The obtained NiO microspheres possessing accessible nanopores, excellent structural stability and large surface area up to 130 m²/g show promising electrochemical performance in anodic lithium storage for lithium-ion battery