In-situ growth of flower-like CuS microsphere on carbonized cotton for high-performance flexible supercapacitor

Abstract In this work, a composite electrode of flower-like copper sulphide (CuS) and carbonized cloth is prepared by one-step surfactant-free hydrothermal method simply. The reaction time has a great influence on the secondary structure of CuS, and the CuS nanosheet grown in situ on the carbonized cloth with lamellar structure possesses good dispersibility when the reaction time is 4h, which could provide more active sites to facilitate electrochemical reaction. Besides, due to the synergistic effect of pseudo capacitance of CuS and double layer capacitance of carbonized cloth, the CuS/carbonized cotton (CSCC-4) shows not only great specific capacitance (4176 mF cm −2 at current density of 2 mA cm −2 ) but also outstanding cycle stability (15.1% loss of initial capacitance over 5000 cycles). Moreover, it is worth noted that the symmetrical flexible SC based on CSCC-4 electrodes accomplishes a great energy density, which reaches to 0.74 Wh cm −2 at power density of 4.35 W cm −2 and maintains 0.26 Wh cm -2 at power density of 21.9 W cm -2 .