Three-dimensional hierarchical graphene and CNT-coated spinel ZnMn2O4 as a high-stability anode for lithium-ion batteries

Abstract

ZnMn2O4, with theoretical specific capacity of 1008 mAh g−1, is a promising anode material for lithium-ion batteries. It attracts intensive research interests not only because of its high specific capacity, but also due to its low cost, abundant resources and environmental friendliness. However, its poor reaction kinetics, low intrinsic electrical conductivity and large volume changes upon cycling impede its commercial application. In this work, we demonstrate a method to effectively synthesize a three-dimensional, layered network architecture utilizing reduced graphene oxide (rGO) and cross-linked carbon nanotubes (CNTs) as substrates for ZnMn2O4 nanoparticles. The ZnMn2O4 nanoparticles are grown in-situ on the surface of both the rGO and the CNTs. The results show that the composite samples display a significantly enhanced electrochemical performance when compared with their pristine counterparts. In particular, the ZnMn2O4-rGO/CNT composite anode delivered an enhanced capacity of 606 mAh g−1 at 1.0 A g−1 after 1000 cycles with an 83% capacity retention. The synergistic effect between the rGO and the CNTs is believed to be the reason for the improved performance. In-situ X-ray diffraction (XRD) was used to successfully reveal the electrochemical conversion reaction mechanism of the new ZnMn2O4 anode.