Facile synthesis of freestanding cellulose/RGO/silver/Fe2O3 hybrid film for ultrahigh-areal-energy-density flexible solid-state supercapacitor

We report the design of a freestanding cellulose/RGO/silver/Fe 2 O 3 hybrid film for direct use as electrodes for construction of high-performance flexible solid-state supercapacitor (FSS). It is well characterized and found to feature noticeable capacitive properties due to the unique structure, high conductivity and dual electroactive species (i.e., RGO and Fe 2 O 3 ) for charge storage. As demonstrated in a three-electrode system, such film electrode achieves the maximum areal and volumetric capacitance of 2044 mF cm −2 and 75.7 F cm −3 , respectively, with prominent rate performance and long-term cyclic durability. Later, a symmetric FSS device is constructed by employing this film as both anode and cathode electrodes. The as-assembled device offers the highest areal and volumetric capacitance of 1132 mF cm −2 and 18.2 F cm −3 , respectively, displays inconspicuous performance degradation under different curved states, and possesses the largest areal energy density of 226.4 μWh cm −2 , which is far better than that of many advanced symmetric and asymmetric flexible supercapacitors. The attractive capacitive behaviors and easy fabrication processes could render cellulose/RGO/silver/Fe 2 O 3 hybrid film a promising material for the applications in next-generation flexible and wearable electronics in the future.