Design-guided synthesis of customizable carbonized electrodes for maximizing charge storage in carbon-based supercapacitors

3D carbon foams, CarboHIPEs, were successfully developed as self-standing electrodes for supercapacitor applications through the sulfonation and pyrolysis of polymerized High Internal Phase Emulsions. The fabrication process was systematically optimized by investigating the influence of sulfonation duration and pyrolysis temperature on the structural, chemical, and electrochemical properties of the resulting materials. A prolonged sulfonation time of 24 h significantly enhanced char yield, while increasing the pyrolysis temperature promoted micropore development, leading to a high specific surface area of up to 579 m 2 g −1 and apparent electrical conductivity of 1.3 ± 0.2 S cm −1 . An optimal pyrolysis temperature of 800 °C provided the best balance between conductivity, hierarchical porosity, and heteroatom retention, resulting in superior electrochemical performance. The unique combination of interconnected macroporosity, microporous texture, and heteroatom functionalities enabled efficient ion transport and charge storage. Electrochemical characterization demonstrated the best performance in 1 M H 2 SO 4 , with stable specific and volumetric capacitances reaching 80 F g −1 and 50 F cm −3 , respectively. Notably, self-standing nature of the electrode eliminates the need for binders and conductive additives while significantly reducing current collector size, highlighting a significant advantage over conventional powder-based carbon electrodes. Symmetric supercapacitor devices assembled from CarboHIPE electrodes delivered a cell capacitance of 6.4 F cm −3 , together with a maximum energy density of 6.6 mWh cm −3 at a power density of 60.5 mW cm −3 . The devices exhibited excellent long-term durability, retaining stable performance over 12,000 charge–discharge cycles. These results demonstrate that CarboHIPEs constitute a promising and scalable electrode platform, combining facile processing, binder-free architecture, robust cycling stability, and competitive electrochemical figures of merit for next-generation energy storage systems.