3D Interconnected Graphene-like Porous Materials Derived from Sesbania for High-Voltage Aqueous Supercapacitors

Graphene-like materials are renowned for their excellent electrical conductivity, large surface area, and high energy storage capability. In this study, three-dimensional (3D) interconnected graphene-like porous materials were synthesized from Sesbania, a sustainable biomass, via acid-assisted hydrothermal carbonization, followed by KOH activation. The resulting material (SE_GLC) features interconnected open pores within graphene-like sheets and boasts a surface area of 1140 m²/g. Its performance as an electrode in a symmetric supercapacitor was evaluated using a cost-effective 12 m NaNO₃ "water-in-salt" (WIS) electrolyte to enhance energy density by widening the voltage range. The SE_GLC//SE_GLC pouch cell achieved a stable operating voltage of 1.9 V, delivering a high gravimetric energy density of 23.83 Wh/kg and a power density of 189.83 W/kg. Notably, even at a specific power of 5.69 kW/kg, it retained a specific energy of 9.49 Wh/kg. This work highlights the successful synthesis of interconnected graphene-like materials from biomass and their exceptional electrochemical performance with an economical WIS electrolyte, underscoring their potential for sustainable energy storage solutions.