A novel high performance flexible supercapacitor based on porous carbonized cotton/ZnO nanoparticle/CuS micro-sphere

In this work, a novel flexible electrode composed of porous carbonized cotton, ZnO nanoparticles and CuS micro-spheres is prepared by two-step method. Benefitting from the synergistic effect of eletrochemical double layer capacitance and pseudo capacitance, the porous carbonized cotton/ ZnO/CuS composite (pCcZC) electrode shows excellent specific capacitance (1830 mF cm −2 at 2 mA cm −2 ), high rate performance (74% retention with the current density increasing from 2 to 10 mA cm −2 ) and outstanding cycle stability (14.8% loss of initial capacitance after 5000 cycles). The flexible and lightweight carbonized cotton as current collector directly makes the electrode binder-free, flexible and wearable. Additionally, the flexible symmetrical supercapacitor based on pCcZC electrodes achieves a superior energy density of 0.27 Wh cm −2 at 4.26 W cm −2 , and can succesfully light the LED, which manifests its great applied potential in the new generation of portable and wearable energy storage devices.