Nano-cladding of natural microcrystalline cellulose with conducting polymer: preparation, characterization, and application in energy storage

Abstract

This study demonstrates the possibility to coat individual fibers of natural microcrystalline cellulose with polypyrrole using in situ chemical polymerization to obtain an electrically conducting continuous high charge storage capability composite with a nano-cladding structure. By manipulating the ordered nano-cladding nanostructure, conducting nanocomposites were achieved and outstanding electrical conductivity, as high as 48.7 S cm⁻¹, was obtained with the feeding mass ratio of sisal microcrystalline cellulose SMC : Py = 3 : 7. X-ray photoelectron spectroscopy (XPS) results showed that with the increase in SMC content, doping level of PPy in the composite increased. It was found that the PPy nanoparticles deposited on the surface of the SMC and connected to form a continuous cladding. The as-prepared SMC/PPy nanocomposites demonstrated a mass-specific capacitance (C_s) of 367 F g⁻¹ at a 0.2 A g⁻¹ current density in the supercapacitor application. Moreover, SMC/PPy electrode retained about 87.5% of the initial C_s after 1000 cycles, and about 57.8% of C_s when the current density increased five times. This study provides a straightforward method to utilize the renewable resource sisal microcrystalline cellulose to obtain a conducting composite, which could be applied in sensors, flexible electrodes, and flexible displays. It also opens a new field of potential applications of micrometre-scale natural microcrystalline cellulose.