RuO2-coated vertical graphene hybrid electrodes for high-performance solid-state supercapacitors†
Hybrid electrodes consisting of ruthenium dioxide (RuO2) and graphene hold great promise in the development of high-performance supercapacitors. However, the present methods for fabricating RuO2/graphene hybrids are complex and costly, preventing their widespread applications. Here, we demonstrate a simple, scalable and cost-effective method to prepare hybrid electrodes composed of RuO2 and vertical graphene (VG). VG is used as the support to offer several unique features, including a three-dimensional (3D) porous structure, a large surface area, good mechanical rigidity and high electrical conductivity. With a solution-free reactive magnetron sputtering method, RuO2 can be uniformly coated on VG with controllable loading. Solid-state supercapacitors assembled using the binder-free RuO2/VG hybrids and a polymer gel electrolyte possess a high areal capacitance, low electrical resistance, good frequency response, and excellent capacitance retention after 10 000 cycles of charging and discharging. Our results demonstrate the potential of RuO2/VG hybrids in developing high-performance solid-state supercapacitors in a cost-effective manner, paving the way towards the commercialization of various Ru-based energy storage devices.