Synthesis of a nanowire self-assembled hierarchical ZnCo2O4shell/Ni current collector core as binder-free anodes for high-performance Li-ion batteries

Abstract

In this paper, ZnCo₂O₄ nanowires have been grown and self-assembled as hierarchical structures on a 3D conductive Ni foam substrate. Both leaf-like ZnCo₂O₄ and dandelion-like ZnCo₂O₄ assemblies were synthesized through a hydrothermal process followed by a post-annealing treatment. It is shown that leaf-like assemblies are directly grown on the substrate while dandelion-like assemblies are adsorbed on the surface of the structures. A possible formation mechanism of ZnCo₂O₄ hierarchical structures was proposed. It is shown that these nanowires are porous structures which provide much increased specific surface area. Further work was conducted by taking these Ni foam supported ZnCo₂O₄ structures as binder-free electrodes for Li-ion batteries. Remarkably, the leaf-like ZnCo₂O₄/Ni foam electrode exhibits greatly improved electrochemical performance with high capacity and excellent cycling stability. A high reversible capacity of 1050 mA h g⁻¹ at the rate of 100 mA g⁻¹ was obtained after 60 cycles. Meanwhile, the electrode showed a high rate of 416 mA g⁻¹ with a high capacity of 850 mA h g⁻¹ even after 50 cycles. Our work demonstrates that this unique nanowire self-assembled ZnCo₂O₄ hierarchical structure is promising for high-performance electrochemical energy applications.