Facile one-step hydrothermal synthesis of zinc vanadate nanomaterials enhanced via reduced graphene oxide for ultra-long life asymmetric supercapacitors

Abstract

The novel transition metal vanadate materials with hierarchical nanostructures have attracted considerable attention due to their remarkable electrochemical properties in catalysis and energy storage/conversion systems. Herein, we report the zinc vanadate (Zn3V2O10) nanomaterials (ZVO NMs) by a simple one-step hydrothermal method. The synthesis of ZVO NMs is studied at different growth temperatures (100, 150, and 200 °C). Additionally, reduced graphene oxide (rGO) sheets are introduced into the optimized ZVO NM obtained at 150 °C (i.e., ZVO NM-150). The prepared materials are analyzed by various characterization techniques and the obtained properties of ZVO NM with rGO sheets are beneficial for energy storage devices. The ZVO NM-150@rGO electrode exhibits a high specific capacity (capacitance) of 95 mAh g−1 (677 F g−1) at 2 A g−1 with a rate capability of 82 % in 1 M KOH aqueous electrolyte solution. The ZVO NM-150@rGO electrode reveals superior capacity retention of 105 % with Coulombic efficiency (CE) of 98 % after completing 45,000 cycles. Furthermore, the assembled asymmetric supercapacitor (ASC) device demonstrated maximum energy and power densities of 19.06 Wh kg−1 and 2190.78 W kg−1, respectively. The ASC device also shows good cycling stability with excellent capacitance retention of 139 % and CE of 98 % after 80,000 cycles. Benefiting from these advantageous properties, the ZVO NM and ZVO NM-150@rGO electrode materials are very promising for high-performance SCs.