Potassium Bicarbonate‐Assisted Pore Regulation of Corn‐Straw‐Derived Interconnected Porous Carbon for Supercapacitors

Abstract

ABSTRACT Biomass‐derived porous carbons are promising electrodes for sustainable supercapacitors, but their performance depends on balancing charge‐storage sites and ion‐transport pathways. Herein, corn straw was converted into interconnected porous carbon through mild KHCO 3 ‐assisted activation. The effects of activation temperature and holding time on pore architecture and capacitive behavior were comparatively evaluated, and the surface chemistry of the best‐performing sample was further examined. CSK‐750‐2, prepared at 750°C for 2 h, exhibited a hierarchical porous structure containing micropores and mesopores with a specific surface area of 1701 m 2 g −1 . Micropores provided abundant surface area for electric double‐layer charge storage, whereas mesopores facilitated electrolyte‐ion transport, and surface oxygen‐containing groups may provide a limited Faradaic contribution. CSK‐750‐2 delivered 157 F g −1 at 0.5 A g −1 with 86% capacitance retention at 5 A g −1 . The symmetric supercapacitor achieved 10.5 Wh kg −1 at 500 W kg −1 and approximately 106% capacitance retention after 10,000 cycles. These results highlight the importance of balancing micropore‐based charge storage and mesopore‐assisted ion transport in biomass‐derived carbon electrodes.