High-performance aqueous symmetric supercapacitors with a versatile 3D reduced graphene oxide aerogel electrode

In this study, we present a versatile electrode material for high-performance, aqueous symmetric supercapacitors based on reduced graphene oxide (rGO) aerogel. Electrode material was synthesized using hydrothermal approach without any additional reagents and exhibited developed porosity with a robust, interconnected 3D structure which deemed favorable for electrical charge storage. In 1 M Na2SO4, the symmetric device exhibited a maximum operating voltage of 2.0 V, surpassing the theoretical limit for water decomposition and delivering impressive energy densities of 28.5 and 18.6 Wh kg−1 at power densities of 0.154 and 1.363 kW kg−1, respectively. The versatility of the rGO aerogel was further demonstrated in 1 M H2SO4 and acidic hydroquinone-enriched electrolytes. The hybrid supercapacitor with the redox-active electrolyte showed a remarkable specific capacitance of 288 F g−1 at a current density of 0.2 A g−1 within a potential window of 0 to 1.4 V. Furthermore, the hybrid device maintained 98% of its initial capacitance after 12000 charge/discharge cycles, proving its excellent long-term stability. These results highlight the promise of the rGO aerogel in the development of high-performance aqueous supercapacitors, offering a combination of sustainable synthesis, excellent electrochemical properties, and compatibility with diverse electrolytes.