LAUSR

In this study, freestanding paper-like composite films were fabricated using a simple, but scalable and efficient, approach: an environmentally friendly freeze-and-thaw process giving a porous fibrous matrix of cellulose and functionalized carbon nanotubes (f-CNTs), followed by in situ chemical polymerization for the incorporation of polypyrrole (PPy). A homogeneous porous fibrous matrix was formed as a result of strong hydrogen bonding between the f-CNTs and the regenerated cellulose; this material served as an excellent template for the uniform coating of PPy. The structural, morphological, thermal, and electrochemical properties of the as-prepared PPy/f-CNT/cellulose composite films were investigated to evaluate their potential for use as flexible, lightweight, and inexpensive freestanding electrode materials within flexible supercapacitors. The unique microstructure—with high electrical conductivity, good wettability, and a porous architecture—provided large interfacial areas for the storage/release of charge carriers and for the facile diffusion of electrolyte ions in the prepared composite electrodes. With these attributes, the freestanding electrode having the optimal PPy loading exhibited not only an excellent areal capacitance (2147 mF cm−2 at a current density of 1 mA cm−2) but also a good rate capability and an outstanding cycling stability. Moreover, the flexibility, environmental friendliness, and biodegradability of the PPy/f-CNT/cellulose composite films suggest that they will be suitable for use as green and sustainable electrode materials within flexible supercapacitors.Graphical abstract