Efficient Extraction of Phenols from Coal Tar and Preparation of Phenolic Resin-Based Porous Carbon for Advanced Supercapacitor Application

Developing simple and efficient extraction methods for phenolic substances from coal tar, which facilitate their direct transformation into high-performance electrode materials, holds considerable practical significance. In this study, amide-zinc chloride deep eutectic solvents are employed for efficient phenol extraction. The optimal phenol extraction process is subsequently investigated, and it is found that the robust hydrogen bonding interactions between solvents and phenols significantly enhance extraction efficiency. Notably, without the need for back-extraction, formaldehyde and tetraethyl orthosilicate are added to obtain phenolic resin, which can subsequently be directly carbonized to fabricate hydrangea-like porous carbon. The carbonization mechanism of the phenolic resin is studied, and the templating and activating roles of tetraethyl orthosilicate and zinc chloride assist in the formation of this unique structure. Furthermore, the flexible supercapacitor assembled using the prepared porous carbon and gel electrolyte achieves a high energy density of 31.0 Wh kg^-1 and demonstrates broad temperature applicability ranging from -25 to 100 °C. This work directly converts the extracted phenolic compounds into phenolic resin and shows potential for fabricating porous carbon materials with diverse structures and enhanced capacitive performance.