Preparation and Characterization of Free-Standing Electrode Materials from Waste Cotton Fabrics for Electric Double-Layer Capacitors

The upcycling of waste materials to fabricate high-performance electrode materials is of great interest for future energy storage devices. In this paper, we suggest an efficient strategy of upcycling waste cotton fabrics (WCFs) into freestanding carbon fabrics (CFs) via two-step thermal treatment. The prepared CFs exhibited a large specific surface area, multimodal pore structures, flexible free-standing structural properties, and good electrical conductivity. The electrochemical performance of the CFs was investigated by cyclic voltammetry, galvanostatic charging/discharging tests, and electrochemical impedance spectroscopy. In a three-electrode system, the binder-free CF-based electrode exhibited a gravimetric specific capacitance of 198 F g−1 at 1 A g−1 in a 6 M KOH aqueous electrolyte. The binder-free and current collector-free CF-based symmetric capacitor showed an areal capacitance of 262 mF cm−2 at 2 mA cm−2, a gravimetric capacitance of 29.4 F g−1 at 1 A g−1, a maximum gravimetric power density of ∼3000 W kg−1 at an energy density of 3.21 Wh kg−1, an areal power density of ∼25,000 mW cm−2 at an energy density of 23.53 mWh cm−2, and an excellent cycle stability of ∼100 % at 100 mA cm−2 after 10,000 cycles. These results reveal that WCFs can be a promising precursor material for the preparation of free-standing carbon-based electrode materials in various energy storage devices.