Stacked Bilayer Graphene and Redox-Active Interlayer for Transparent and Flexible High-Performance Supercapacitors

Fabrication of a transparent and flexible supercapacitor requires electrode materials that are optically transparent and mechanically flexible. Although chemical vapor deposition (CVD)-grown graphene is a promising electrode material, its use in supercapacitor applications is greatly limited by the low area-specific capacitance of the fabricated supercapacitor. Here, we demonstrate transparent and flexible high-performance supercapacitor using stacked bilayer graphene and an ultrathin redox-active interlayer. By inserting the redox-active layer between stacked bilayer graphene, we achieved an almost 20-fold enhancement of the area-specific capacitance (from 5.6 μF/cm2 to 101 μF/cm2) with a thickness of electrode material for each electrode less than 2 nm. In addition, the fabricated supercapacitor exhibited excellent transparency of 75% (including the substrate's transparency) and flexibility (bending radius down to 5 mm) by virtue of the outstanding transparency and flexibility of the stacked bilayer graphene and redox-active interlayer.