Hierarchical NiO nanobelt film array as an anode for lithium-ion batteries with enhanced electrochemical performance

In this study, an ultrathin 2-dimensional hierarchical nickel oxide nanobelt film array was successfully assembled and grown on a Ni substrate as a binder-free electrode material for lithium ion batteries. In the typical synthesis process, the evolution of the nickel oxide array structure was controlled by adjusting the amount of surfactant, duration of reaction time and hydrothermal temperature. By virtue of the beneficial structural characteristics of the nanobelt film array, the as-obtained NiO array electrode exhibits excellent lithium storage capacity (1035 mA h g^-1 at 0.2C after 70 cycles and 839 mA h g^-1 at 0.5C after 70 cycles) for LIBs. This excellent electrochemical performance is attributed to the nanobelt film (3-5 nm thickness) array structures, which have immense open spaces that offer more Li⁺ storage active sites and adequate buffering space to reduce internal mechanical stress and shorten the Li⁺ diffusion distance. Additionally, this array structure is designed to achieve a binder-free and non-conductive additive electrode without complex coating and compressing during the electrode preparation process.