Supramolecular engineering of cellulose-polyaniline composites using CuTA for superior energy storage applications.

Cellulose, the most abundant biomass, is highly appreciated for its robustness, biodegradability, and renewability, garnering significant interest for innovative applications in sustainable functional materials. Composites of cellulose and polyaniline (PANI) are particularly promising for flexible supercapacitors because of their ease of processing, excellent electrical conductivity, and high theoretical specific capacitance. However, challenges persist due to the tendency of PANI to agglomerate and the weak interfacial interactions between PANI and cellulose fibers (CFs). Herein, copper tannin (CuTA), a metal-phenolic supramolecular complex, is utilized to strengthen the interface between the cellulose and PANI, while also modulating the nanostructure of the PANI layer to create high-performance cellulose-based flexible electrodes. Consequently, after incorporating CuTA, the composite electrodes demonstrated a significantly high capacitance of 5147 mF/cm2. Furthermore, the mechanism underlying the superior energy density of supercapacitors is investigated. This strategy provides a novel method for promoting the development of green, economical, and high-performing cellulose-based supercapacitors.