Three-Dimensional Network of Vanadium Oxyhydroxide Nanowires Hybridize with Carbonaceous Materials with Enhanced Electrochemical Performance for Supercapacitor

It is always worthwhile to develop novel composite electrode materials for supercapacitors, especially the combination of stable conductive structures and metal oxides with high electrochemical performance. Compared with vanadium oxides, vanadium oxyhydroxide has been paid rare attention as energy storage materials. Herein, a 3D hierarchical VOx(OH)y/carbon nanotube (CNT)/reduced graphene oxide (rGO) composite is synthesized by a facile self-assembly method. CNT/rGO networks act as structure-directing agent and provide excellent conductivity. VOx(OH)y anchored to CNT/rGO networks is a novel vanadium oxyhydroxide with a mixed-valence V+4/+5, composed of major V3O5(OH)4 and minor V2O5·H2O. The VOx(OH)y/CNT/rGO composite electrode exhibits a high specific capacitance of 414 F·g–1 at 0.5 A·g–1 within the potential range of −1.2 to +0.6 V in 1 mol·L–1 LiClO4/PC. The symmetrical supercapacitor can deliver a high energy density of 60.90 Wh·kg–1 at a power density of 81.85 W·kg–1 with a large voltage window of 2.2 V. The preeminent electrochemical properties are because of the synergistic effects from VOx(OH)y nanowires and conductive CNT/rGO networks. The impressive results illustrate that a symmetric supercapacitor is expected and promising for energy storage devices.