Blow-Room Cotton Waste-Derived Activated Carbon for Supercapacitor Electrodes

Reem Shahin, Alexey Rodin

Article
2026 / Volume 9 / Pages 1016-1035
Received 9 December 2025; Accepted 24 February 2026; Published 27 April 2026
https://doi.org/10.31881/TLR.2026.1016

Abstract
Cotton-based waste has increased with the expansion of the textile industry, and despite its rich cellulose content, a large amount of it is thrown away. Simultaneously, the increasing need for high-performance and sustainable energy storage devices has drawn attention to activated carbon (AC) generated from biomass as supercapacitor electrode materials. Converting cotton waste into AC provides an environmentally friendly path to produce useful electrode materials. In this study, blow-room cotton waste was chemically activated using phosphoric acid (H₃PO₄) at two concentrations (50 and 85 wt%) to examine its influence on yield, morphology, and electrochemical behavior. After impregnation and carbonization at 600 °C, the resulting powders were labeled AC-50 and AC-85. Increasing H₃PO₄ concentration reduced activation yield from 24.7 wt% to 20.8 wt% and volatile matter from 9.3 to 6.1 wt%, while increasing fixed carbon and ash content. FT-IR indicated the loss of cellulose features and stronger P–O/P=O bands for AC-85, suggesting deeper phosphorylation. SEM revealed the extensively interconnected pore network for AC-85. Electrodes prepared using AC samples were tested in symmetrical CR2025 cells with 1 M KNO3. Cyclic voltammetry and galvanostatic charge–discharge confirmed electric double-layer behavior, with AC-85 achieving higher capacitance (135.6 F g⁻¹ at 1 mV s⁻¹) and better rate performance. Ragone data and EIS further showed lower resistance and improved ion transport for AC-85. Overall, concentrated H₃PO₄ produces AC with richer surface functionality, and superior electrochemical performance, highlighting a potential route to convert blow-room cotton waste into promising electrode materials for supercapacitors.

Keywords
cotton waste, activated carbon, chemical activation, phosphoric acid, supercapacitor electrodes