Facile fabrication of reduced graphene oxide covered ZnCo2O4 porous nanowire array hierarchical structure on Ni-foam as a high performance anode for a lithium-ion battery

Abstract

We successfully prepared a nanostructure from ZnCo₂O₄ nanowire arrays directly grown on a Ni-foam substrate, with a surface decorated with reduced graphene oxide (rGO), through a very simple and cost-effective two-step facile fabrication using a hydrothermal method together with calcination treatment, followed by electro-deposition. It is shown that there are plenty of pores distributed along each of the nanowires, providing a large specific surface area. We also observe that the rGO thin flakes have indeed covered the ZnCo₂O₄ nanowires. This binder-free hierarchical composite on a Ni substrate was further used as an anode for lithium ion batteries. It displays a largely improved electrochemical performance, with a high capacity, excellent cycling stability and good rate capability, compared to both the anode without rGO covering and the anode with binder and conductive additive. It can retain a high discharge capacity of 1208 mA h g⁻¹ after 100 cycles at the rate of 0.1 A g⁻¹, and in the mean time, it can also provide a high capacity of 1032 mA h g⁻¹ after 100 cycles even at a high rate of 0.5 A g⁻¹. In this paper we prove that our rGO covered ZnCo₂O₄ nanowire array hierarchical structure supported on a Ni-foam substrate is a promising anode material for high performance lithium storage devices.