3D hierarchical porous ZnO/ZnCo2O4 nanosheets as high-rate anode material for lithium-ion batteries

Abstract

Hierarchical porous ZnO/ZnCo₂O₄ (denoted as ZZCO) nanosheets have been successfully synthesized by one-step thermal annealing of the as-prepared Zn–Co-MOF precursor. The ZZCO nanosheets are composed of uniform sized, interconnected primary ZnO and ZnCo₂O₄ (donated as ZCO) nanoparticles (NPs), which are homogeneously dispersed in the products. Moreover, it possesses favorable features, such as a three-dimensional hierarchical nanosheet structure for fast charge transfer, high porosity from the MOF and good structural stability. This hierarchical porous ZZCO nanohybrid is found to be very attractive for lithium-ion batteries. A reversible capacity of 1016 mA h g⁻¹ was maintained after a repetitive 250 cycles at 2 A g⁻¹ with a remarkable coulombic efficiency of almost 99% and even when the current was 10 A g⁻¹, a capacity of 630 mA h g⁻¹ was attained. The excellent electrochemical performance should be due to the advantageous structural and compositional features.