Linking macroscopic surface morphology of activated carbon fibres and electrosorption performance: An electrochemical impedance spectroscopy and capacitive deionization study

Abstract

Activated carbon fibres (ACFs) are successful electrode materials for capacitive deionization (CDI) owing to their excellent electrochemical properties and commercial availability, for example, with knitted or woven morphology patterns. However, the lack of a common and effective analytical framework to analyse the performance of ACFs is hindering further progress in the area. This study establishes an electrochemical impedance-based method to detect and investigate the electrochemical properties of ACF materials without destroying their original weaving patterns. Five commercial ACFs with two distinct patterns and similar specific surface areas were investigated. Data from electrochemical impedance spectroscopy (EIS) are compared to the desalination performance and energy consumption of the ACFs in a CDI cell. The weaving pattern played a role in the electrochemical properties and desalination performance. The volume-salt adsorption capacities in CDI were related to the volume-specific capacities in EIS, however, there was no significant difference between knitted and woven materials. Linked to EIS features, knitted ACFs consume less energy than woven ACFs for removing the same amount of NaCl from water. These results provide ACF researchers with a new, effective, and readily available approach for measuring the electrochemical performance of ACF materials via EIS.