Preparation of Hierarchically Porous, Self‐Doped Carbon Electrodes with Rib‐Layered Structures from Ipomoea Aquatica Biowaste for High‐Performance Symmetric Supercapacitors

Environmentally friendly, sustainable, and low‐cost, biomass‐derived carbon materials have emerged as promising candidates for high‐performance supercapacitor electrodes. However, the effective transformation of biomass residues into advanced functional materials remains challenging. In this study, Ipomoea aquatica, a nitrogen‐rich biomass with a naturally ribbed lamellar structure, is employed to synthesize a series of porous carbon materials (IACC) through a two‐step carbonization and KOH activation process. Benefiting from its intrinsic ribbed‐layered framework and the synergistic effects of hierarchical porosity and nitrogen doping, the resulting carbon exhibits a highly interconnected porous network and enlarged specific surface area. Among them, the IACC‐5 electrode delivers a high specific capacitance of 287.2 F g −1 at 0.5 A g −1 while maintaining over 88% capacitance retention after 10 000 charge–discharge cycles. Furthermore, a symmetric supercapacitor assembled using IACC‐5 electrodes achieves a high energy density of 39.94 Wh kg −1 and a power density of 250 W kg −1 . This study highlights the structural and compositional advantages of Ipomoea aquatica‐derived carbon, demonstrating a sustainable and efficient strategy for designing next‐generation energy storage materials.