Solid-state, high-performance supercapacitor using graphene nanoribbons embedded with zinc manganite

The fabrication of flexible supercapacitor involves the challenging task of preparing flexible electrodes with a large capacitance and robust mechanical strength. We report here the formulation of a high-performance solid-state flexible supercapacitor using graphene nanoribbons embedded with zinc manganite (ZnMn2O4/GNR) as the electrode and a gel polymer membrane as the electrolyte. The in situ availability of the graphene oxide nanoribbons led to the uniform dispersion of ZnMn2O4 nanospheres (about 7 nm), resulting in enhanced transport of the electrolyte ions. The fabricated ZnMn2O4/GNR parallel to ZnMn2O4/GNR supercapacitor was optimized with a maximum operating cell potential of 2.7 V. It delivered an energy density of about 37 W h kg(-1) and had a power density of about 30 kW kg(-1) at 1.25 A g(-1) with good cycling stability over 4000 cycles. The high diffusion coefficient and short relaxation time of 0.34 mu s (at 75 degrees C) are indicators of its high performance and stability at increased temperature. The superior flexibility and durability of the supercapacitor cell are evidence of their performance stability over consecutive galvanostatic charge/discharge cycles under harsh conditions.