High Performance Flexible Supercapacitor Electrodes Composed of Ultralarge Graphene Sheets and Vanadium Dioxide

Little is known regarding the effect of the graphene lateral size on the electrochemical performance of hybrid graphene electrode. This work examines the electrochemical performance of a flexible hybrid supercapacitor electrode composed of ultralarge graphene oxide (UGO; mean lateral size of 47 ± 22 μm) and vanadium dioxide (VO₂) nanobelts, referring to a reference electrode composed of small scale graphene oxide (SGO; mean lateral size of 0.8 ± 0.5 μm) and VO₂.Thermal treatment converts UGO/VO₂ and SGO/VO₂ to URGO/VO₂ (denoted VURGO) and SRGO/VO₂ (denoted VSRGO) electrodes, respectively. The sheet resistance of the VURGO film (0.57 ± 0.03 kΩ sq.^–1) was two orders of magnitude lower than that of the VSRGO (55.74 ± 9.35 kΩ sq.^–1). The VURGO hybrid electrode showed a specific capacitance of 769 F g⁻¹, which was significantly better than the corresponding values for the VSRGO electrode (385 F/g). These results support the notion that the use of ultralarge graphene sheets (≈22 500 μm²) lowers the intersheet resistance due to the presence of fewer intersheet tunneling barriers. This article highlights the potential utility of URGO (as a conductive support) in hybrid electrode containing VO₂ nanobelts for high performance flexible hybrid supercapacitor.