Robust hollow Bowl-like α-FeO nanostructures with enhanced electrochemical lithium storage performance.

The design and synthesis of hollow-nanostructured transition metal oxide-based anodes is of great importance for long-term operation of lithium ion batteries (LIBs). Herein, a special hollow bowl-like α-FeO nanostructure is controllably synthesized through a facile hydrothermal technique and exhibits great electrochemical lithium storage performance when used as LIBs anode. Under a facile hydrothermal condition, α-FeO nanostructures evolve from solid pie-like structure to hollow bowl-like structure and finally α-FeO nanorings through the regulation of HPO derived from ionized NaPO·12HO and Ostwald ripening process. The designed hollow bowl-like α-FeO nanostructure not only has the merits of hollow structure, which can accelerate the diffusion of lithium ions and electrons, but also shows great mechanical strength to disperse stress when compared to solid pie-like and ring-like α-FeO nanostructures, which would avoid collapse during charge/discharge process. As a result, the as-synthesized hollow bowl-like α-FeO nanostructure displays an initial reversible capacity of 1616 mAh g at a current density of 1 A g, an excellent cycling performance with a reversible capacity of 1018 mAh g after 500 cycles and an outstanding rate capability (68.1% capacity retention at current densities from 100 to 2000 mA g). This work provides not only a novel hollow bowl-like α-FeO nanostructure with high specific surface area and stable structure as potential electrode materials for energy storage, but also a facile self-templated strategy free of any surfactants and templates for hollow nanostructures.