Electrodeposited CuS nanosheets on carbonized cotton fabric as flexible supercapacitor electrode for high energy storage

With the large theoretical capacity and environmental benignity, copper sulfide (CuS) becomes a prospective candidate electrode material for supercapacitors. In this work, electroconductive mesoporous carbonized clothes (Cc) was obtained by carbonizing the waste cotton fabrics. Then the CuS was galvanostatic electrodeposited on Cc to prepare the binder-free g-CuS/Cc electrode. In the galvanostatic electrodeposition process, CuS grew along the crystal surface to form regular nanosheets, and a part of Cu2+ were reduced to Cu1.1+. In addition, on account of the synergistic effect of electrochemical double layer capacitance with pseudocapacitance and the high specific surface area (450.76 m2 g−1), the g-CuS/Cc composite displayed not only outstanding areal specific capacitance (4676 mF cm−2 at 2 mA cm−2) but also excellent cycling performance (89.8% retention after 10000 cycles). Meanwhile, the symmetrical flexible supercapacitor (SC) based on g-CuS/Cc electrodes with PVA-KOH gel electrolyte (g-CuS/Cc-SC) accomplished a high specific capacitance of 1333 mF cm−2 at 2 mA cm−2 as well as ultrahigh energy density of 0.96 Wh cm−2 at the power density of 4.36 W cm−2. Therefore, g-CuS/Cc shows a great potential for applications in the next generation of flexible energy storage devices. [Display omitted] •Electroconductive Cc was prepared by carbonizing the waste cotton fabric.•The binder-free electrode displayed outstanding electrochemical performance.•The growth mechanism of CuS and the electron transfer number during deposition were studied.•The flexible supercapacitor with ultrahigh energy density was fabricated.