Speaker
Description
Interfaces between aqueous electrolyte and porous carbon electrodes critically govern the performance of organic redox flow batteries (ORFBs). In this work, we investigate how pretreatment strategies including O2 plasma, KOH activation, and CO2 activation modify the interfacial properties of carbon felt electrodes by tuning surface chemistry, defect structure, and porosity. Using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), and inverse gas chromatography (iGC), we establish a structure–property relationship linking these modifications to electrochemical behavior in an quinone-based aqueous electrolyte. Although all treatments reduced activation losses, only CO2-activated electrodes maintained enhanced performance over extended cycling (up to 280 cycles). This enhanced performance correlates with the significantly increased surface area and higher defect density introduced by CO2 activation, which promote improved interfacial accessibility and electrochemical activity. While surface fouling that blocks active sites is observed for all samples, CO2-activated electrodes retain superior activity, indicating that interfacial transport and accessibility, rather than surface chemistry alone, govern long-term performance. These results demonstrate that different pretreatment pathways selectively control key aspects of interfacial interactions, including chemical functionality, defect-driven reactivity, and pore structure. This provides design guidelines for developing durable, high-performance electrodes in ORFB systems.