Facile hydrothermal fabrication of ZnO–graphene hybrid anode materials with excellent lithium storage properties

Abstract

ZnO–graphene hybrid materials were successfully synthesized from graphene oxide (GO) and zinc acetate by a facile hydrothermal fabrication method. Three composites of ZnO–graphene hybrids with different graphene incorporation amounts were prepared by changing the dosage of GO. The chemical composition, morphology, and structural characterization reveal that the wurtzite-phase ZnO particles with diameters less than 10 nm were uniformly anchored on the graphene sheets to form ZnO–graphene hybrid materials. The ZnO–graphene hybrids were utilized as anodes in the construction of high-performance lithium-ion batteries. One of the hybrids, the ZnO–HG composite with 71.5 wt% graphene content, exhibits a high reversible specific capacity (749.2 mA h g⁻¹), excellent cycle stability over 100 cycles (70.3% retention), and good rate performance at a high current density of 2 A g⁻¹ (354.1 mA h g⁻¹). Additionally, to further investigate the anodes for practical use in full Li-ion cells, we for the first time, tested the ZnO–graphene anodes at different cut-off voltages. The results show that even at the low cut-off voltage of 0.01–1.0 V, the ZnO–HG anode can still deliver the reversible capacity of 240 mA h g⁻¹, which is qualified for use as an anode material in Li-ion full cells. The excellent performances are attributed to the presence of graphene which has an important role as the ZnO nucleation substrate during preparation, highly conductive agent, and volume expansion buffer during prolonged charge/discharge cycling.