Polyaniline/agricultural waste microcellulose composites as electrode materials for supercapacitors

Abstract

Supercapacitors are energy storage devices that employ carbon, metal oxides, and conducting polymers as electrode materials. Polyaniline (PANI) was polymerized onto microcellulose (MC) to produce an electroactive material suitable for supercapacitor electrode applications. Microcellulose was prepared from cellulose extracted from Cocos nucifera L. (coconut, CLS) leaf sheaths and Oryza sativa straw (rice, RS). Delignification and bleaching procedures yielded 45% and 28% cellulose from CLS and RS, respectively, followed by acid hydrolysis to produce MC. Acid hydrolysis of the extracted cellulose produced MC. PANI was chemically polymerized onto MC using a 50:50, 70:30, and 90:10 aniline:MC ratios. PANI/MC composites were then characterized by SEM, TGA, FTIR, four-point probe conductivity testing and cyclic voltammetry. SEM micrographs indicated the composite was composed of thin ribbonlike strands with a rough surface coating. TGA revealed that extracted cellulose (CLS -312.55 °C; RS -331.50 °C) had lower purity compared to standard cellulose (335.28 °C). FTIR spectra of the composites showed characteristic peaks of both pure PANI and MC. PANI/MC composites with 90:10 ratio gave the highest conductivity values, ranging from 36.4 µScm -1 to 39.0 µScm -1 ; and specific capacitance values of 51.2 F g -1 to 109 F g -1 at 50 mV s -1 . The results showed effective utilization of waste residues capable of increasing the potential of PANI as an electrode material for supercapacitors.