Tunable morphology and property of a MnO₂/carbonized cotton textile hybrid electrode for electrochemical capacitors

There is an increasing demand of low cost, flexible, stable, and environmentally benign power sources for emerging wearable electronic equipment. Herein, we develop electrochemical capacitor electrodes based on MnO₂/carbonized cotton textile with high mass-loading and tunable morphology. After a simple carbonization process, the cotton cloth with high surface area (585 m² g⁻¹) served as 3D binder-free and flexible scaffolds to anchor MnO₂ nanostructures. The morphology of MnO₂ nanostructures was tuned and optimized into curled sheet-like, which provided large surface area and could also release large local stress. Electrochemical measurements showed that the curled sheet-like MnO₂ had a specific capacitance of 465 F g⁻¹ at 0.1 A g⁻¹, and exhibited an excellent cyclic stability with a specific capacitance retention ratio of 95% after 5000 cycles (at 10 A g⁻¹). Due to the flexible nature of cotton textile, the hybrid electrodes could be bent freely, and the capacitance and cyclability almost remained unchanged even at a bending angle of 150°. Such flexible and stable electrodes from low cost and environmentally benign biomass offer new development potentials for energy storage and wearable electronic applications.