Synergistic activation and structural stabilization of hierarchical porous carbon via gel-directed molten-salt strategy for advanced supercapacitors

Designing porous carbon materials with both high carbon yield and well-developed hierarchical structures remains a major challenge for advancing supercapacitor electrodes. Herein, a gel-salt co-regulation strategy is developed by integrating ZnCl₂/K₂CO₃ activation with biopolymer-derived gel confinement. The dual-salt system, uniformly confined within the gel matrix, leverages the Lewis acidity of ZnCl₂ and the gas-releasing activation of K₂CO₃ to facilitate in-situ pore formation, thereby improving carbon retention and promoting structural evolution. The structurally optimized carbon achieves a high yield of 34.2 %, along with a large specific surface area of 1792.1 m²/g with total pore volume of 1.03 cm³/g, enabling efficient ion transport and a high specific capacitance of 318.8 F/g at 1 A/g in three-electrode systems. Furthermore, the optimized electrodes based symmetric deliver a competitive energy density of 39.2 Wh kg at a power density of 450 W/kg, along with long-term cycling stability of 98.2 % and 96.8 % in KOH and Na₂SO₄ after 15,000 cycles. These results highlight the potential of gel-salt co-regulation as a scalable and effective approach for developing high-performance carbon electrodes with robust long-term operation.