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

[Display omitted] •Freestanding cellulose/RGO/silver/Fe2O3 film is developed as flexible electrode.•Such film electrode releases the maximum areal specific capacitance of 2044 mF cm−2.•Symmetric flexible solid-state supercapacitor device is constructed by this film.•Such supercapacitor device offers the highest areal energy density of 226.4 μWh cm−2. We report the design of a freestanding cellulose/RGO/silver/Fe2O3 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 Fe2O3) 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/Fe2O3 hybrid film a promising material for the applications in next-generation flexible and wearable electronics in the future.