Cross-linker mediated formation of sulfur-functionalized V2O5/graphene aerogels and their enhanced pseudocapacitive performance.

ABSTRACT

The development of efficient synthesis methods for the preparation of vanadium oxide (V2O5)-graphene holds great promise considering the excellent performance of the composite in electrochemical applications. Herein, we report the cross-linking of a V2O5-graphene hybrid via a vanadium-thiourea redox system, which allowed the assembly of graphene oxide functional groups with V2O5 through the reducing ability of thiourea (TU) under room conditions within an impressively short reaction time (20 min). The resulting 3D composite aerogel forms a highly porous architecture of sulfur-functionalized interconnected networks. Such sulfur-functionalized transition metal oxide-graphene-based aerogels are excellent candidates in energy storage applications. When the vanadium oxide-graphene aerogel was evaluated as an electrode for a supercapacitor, a specific capacitance as high as 484.0 F g-1 at 0.6 A g-1 was obtained in a two-electrode cell configuration. This performance is much higher than that of the vanadium oxide-graphene aerogels prepared in the absence of thiourea. The vanadium oxide-graphene aerogel is able to deliver a remarkable energy density of 43.0 Wh kg-1 at a power density of 0.48 kW kg-1 at 0.6 A g-1 and can hold 24.2 Wh kg-1 at a maximum power density of 9.3 kW kg-1 at 10 A g-1. The symmetric supercapacitor assembled from the aerogel can retain 80% of its initial capacitance after 10 000 cycles.