A Facile Synthesis of Porous Activated Carbon with Excellent Electrochemical Properties from Rice Straw for Supercapacitor Electrodes

Abstract The development of sustainable energy storage devices relies heavily on electrode materials with both high performance and cost‐effectiveness. Biomass‐derived porous activated carbons (ACs) have emerged as attractive candidates because of their wide availability and affordability. However, they often exhibit insufficient hierarchical porosity and limited electrochemical performance, necessitating further optimization. Herein, we report a facile and effective strategy to synthesize porous AC from waste rice straw (RS) and systematically investigate the effects of activation temperature, ratio, and sequence. The optimized AC prepared at 900 °C with a 1:4 activation ratio exhibits a hierarchical porous structure and a specific surface area (SSA) of 694.05 m 2 g −1 . It delivers a high specific capacitance of 128.6 F g −1 at 1 A g −1 and excellent rate capability in 6 M KOH using a three‐electrode system. Additionally, the symmetric supercapacitor shows superior cycling stability, retaining 96.6% capacitance after 5000 cycles. These results demonstrate that RS is a promising precursor for porous AC, and that an optimized activation strategy can successfully achieve the desired hierarchical pore structure, thereby significantly enhancing the electrochemical performance. This study provides a sustainable and cost‐effective pathway for converting agricultural waste into high‐value electrode materials for future energy storage applications.