Comparative Study on Alkaline‐Activated Rice Husk Carbon Electrodes: Structure and Supercapacitor Performance

Rice husk‐derived biomass carbon holds strong potential in supercapacitor applications due to its sustainability and low cost. Herein, rice husk carbons are activated using KOH, NaOH, and their mixture, and their electrochemical properties are systematically evaluated. The NaOH‐activated sample achieves the highest specific capacitance of 160.53 F g −1 at 0.5 A g −1 , indicating superior charge storage ability. The mixed alkali‐activated sample exhibits the best cycling stability, retaining 102.41% capacitance after 10,000 cycles, along with the lowest internal resistance (0.05 Ω), reflecting excellent long‐term performance and conductivity. The KOH‐activated sample shows balanced behavior across (97.18% after 10,000 cycles, 0.06 Ω, 154.12 F g −1 at 0.5 A g −1 ). These results suggest that the electrochemical performance is governed by the combined effects of multiple structural and chemical parameters rather than a single dominant factor. This comparative study highlights the distinctive advantages of each activation route and provides valuable insight for tailoring biomass carbon materials toward specific energy storage requirements. This study provides practical guidance for optimizing activation strategies to achieve high‐performance, cost‐effective supercapacitor electrodes from agricultural waste.