Waste Textile-Derived Carbon Integrated with Mixed Metal Oxides for Flexible Supercapacitor Electrodes

Abstract With the rapid growth of electronic and wearable devices, sustainable energy-storage solutions based on waste-derived materials have attracted significant attention. However, high recycling cost and limited energy-storage performance of many waste resources hinder their practical application. To address this challenge, we report a simple and scalable strategy for converting waste cotton textiles into flexible, free-standing supercapacitor electrode, Co3O4@SnO2@NCC-60 (cobalt oxide@stannic oxide@nitrogen-doped carbon cloth). The electrode exhibits a high specific surface area (∼343.61 m2 g−1) with excellent mechanical flexibility and charge-storage capability. In a three-electrode configuration, the Co3O4@SnO2@NCC-60 electrode delivers a specific capacitance of 1263.23 F g−1 at a current density of 1 A g−1, with cycling stability (91%) over 10,000 charge−discharge cycles. A symmetric supercapacitor device assembled using identical Co3O4@SnO2@NCC-60 electrodes and waste cotton cloth as the separator achieves a specific capacitance of 417.98 F g−1 at 3 A g−1. Moreover, a flexible symmetric full-cell supercapacitor delivers an energy density of 56.66 Wh kg−1 at 0.5 A g−1 and maintains stable electrochemical performance under various bending conditions. This work highlights the rational design of a sustainable, high-performance supercapacitor derived from waste textiles, offering significant potential for flexible and wearable energy-storage applications.