Hydrogel-Derived Hierarchical Porous Cosmic Weblike Carbon for High-Performance Supercapacitors in Aqueous Electrolytes

Molecular-modification-based hydrogel precursors have been established as a potential approach for the generation of hierarchical porous carbon material. This paper utilized chitosan as a carbon precursor to produce insoluble gels through the introduction of an aqueous NaOH solution, followed by a one-step carbonization method to prepare three-dimensional porous carbon structures. This material comprises numerous interconnected cosmic web-like networks that facilitate the migration of the electrolyte within the carbon material. The electrochemical energy storage performances of hydrogel-derived hierarchical porous cosmic weblike carbon (HGC) electrodes were measured in various aqueous electrolytes, including 1 M H2SO4, 1 M KOH, and 1 M Na2SO4. In these aqueous electrolytes, the HGC electrode, in a three-electrode configuration, demonstrated high specific capacitances of 475 F g–1, 312 F g–1, and 79 F g–1, respectively, at a current density of 0.5 A g–1. The symmetric supercapacitor, using 1 M H2SO4 electrolyte, exhibited a specific capacitance of 244 F g–1, an energy density of 30.6 Wh kg–1, and a power density of 476 W kg–1 at an operating voltage of 1.0 V. This electrode exhibited a capacitance retention of 98% even after 5000 charge–discharge cycles at a current density of 5 A g–1, demonstrating exceptional cycling stability. The results reveal that supercapacitors exhibit distinct capacitive characteristics across different electrolytes, with optimal electrochemical performance observed in 1 M H2SO4. These findings underscore the potential of HGC as a versatile electrode material for advanced energy storage applications, highlighting its adaptability across various electrolytes and exceptional performance in acidic environments.