High-performance supercapacitors based on hierarchical VOx microspheres forming from hyperbranched nanoribbons

Abstract

Novel VOx nanomaterials as high performance electrode materials of supercapacitors were successfully synthesized by solvothermal method using V2O5, H2O2, (NH4)2SO4 and EG (Ethylene Glycol). These as-prepared nanomaterials are hierarchical microspheres with diameter of~5 μm, which formed from hyperbranched growth of nanoribbons. According to XRD and TEM, these hierarchical VOx microspheres consist of V6O13 with metallic conductivity and VO2. These materials exhibited a tremendous specific capacitance of 581 F/g, with corresponding volumetric specific capacitance of 3.94 F/cm3, at 0.6 A/g in the potential range of 0 to 1.2 V when used as supercapacitor electrodes in a solution of 1 M LiNO3. The energy density is as high as 29 Wh/kg, which is much higher than those of many other symmetrical supercapacitors. In addition, the capacity retention of 65% was achieved even after 2000 cycles, demonstrating high performance of vanadium oxide nanomaterials used in supercapacitors.