Physicochemical Activation for Synergistic Porosity and Functionality Tuning in Supercapacitor Carbon Electrodes

Carbon-based supercapacitor electrodes face critical challenges, including disordered pore architecture, surface inertness, and insufficient graphitization, leading to compromised electron transport and interfacial reactivity. This study systematically investigates the effects of physical or chemical activation strategies on the structural and electrochemical properties of carbon electrode materials. Comparative analysis reveals that physical activation (N₂/CO₂ annealing) primarily induces partial graphitization and moderate particle refinement, while chemical activation involving melamine-assisted heteroatom doping followed by NaOH etching enables comprehensive structural reorganization. The optimized process converts the particle structure into three-dimensional interconnected porous frameworks with enhanced surface functionality. The chemically activated N doped hierarchical porous carbon frameworks (N-CNFs) exhibit (1) hierarchical porosity with optimized meso/micropore coexistence, (2) effective nitrogen incorporation generating redox-active sites, (3) improved charge transfer kinetics through structural graphitization, (4) electrochemical evaluation demonstrates exceptional performance metrics with high specific capacitance of 443 F g^–1 at 1 A g^–1, outstanding cycling stability with 100% capacitance retention after 10,000 cycles at 10 A g^–1 and maximum energy/power density of 21.25 Wh kg^–1 and 15.0 kW kg^–1. This work establishes a paradigm for developing advanced carbon electrodes through coordinated microstructure engineering and surface chemistry modulation, providing critical insights into structure–property relationships for energy storage applications.