Upcycling Cotton–Polyester Textile Waste Into High Quality Biochar and Activated Carbon for Energy Storage Applications

The rapid increase in textile waste generation from fast fashion and population growth calls for innovative waste management and valorization technologies. This study converts textile waste into high‐surface‐area carbon materials through a simple pyrolysis process and investigates the synergistic behavior of thermally decomposing woven cotton–polyester materials. Three waste types‐pure cotton, a 1:1 cotton–polyester blend, and pure polyester—were carbonized at 400, 500, and 600 °C with a slow heating rate (4 °C/min) under nitrogen. The cotton–polyester blend carbonized at 500 °C yielded the highest surface area (576 m 2 /g), outperforming cotton (197 m 2 /g) and polyester (287 m 2 /g). The optimized biochars were subsequently converted into activated carbons via KOH activation, significantly increasing their surface areas (2537 and 1129 m 2 /g for cotton‐ and cotton–polyester‐derived activated carbons, respectively). Electrochemical evaluation of these activated carbons revealed specific capacitances of 112 F/g for cotton‐derived activated carbon and 58.3 F/g for cotton–polyester‐derived activated carbon at 1 A/g. This work demonstrates a scalable approach to upcycle textile waste into high‐performance carbon materials, advancing circular economy initiatives and renewable energy storage technologies.