Binder-free CuS@PEDOT and Co-V-Se electrodes for flexible quasi-solid-state asymmetric supercapacitor

For the development of high-performance modern electronics, fabrication of high-energy density flexible supercapacitors (SCs) composed of advanced functional electrodes with tailored nanoarchitectures is of great significance. Faradaic copper sulphide (CuS) with high theoretical capacity promises great potential as a negative electrode in SCs and to further boost its electrochemical performance, an effective strategy of rational surface engineering by electronically conducting poly(3,4-ethylenedioxythiophene) (PEDOT) is hereby proposed. Herein, construction of novel nanostructured CuS@PEDOT hybrid negative electrode on mechanically flexible conducting carbon cloth (CC) substrate (CC/CuS@PEDOT) via a combined solvothermal and potentiostatic electrodeposition route is successfully demonstrated. Benefiting from high intrinsic reactivity and microstructural characteristics, the CC/CuS@PEDOT hybrid exhibits a marked improvement in areal capacity and ultralong electrochemical cycling stability. As the positive electrodes, nanoarchitectured CC/Co-V-Se (CC/CVS) arrays are prepared and investigated. A novel alkaline polymer gel electrolyte-based quasi-solid-state asymmetric supercapacitor (ASC) assembled with optimized CC/CuS@PEDOT hybrid negative electrode and CC/CVS positive electrode delivers a maximum volumetric energy density of 2.21 mWh cm-3 and superior cycling life (96.7% capacity retention after 10,000 cycles). Additionally, for the ASC device, no obvious performance loss upon bending or twisting is observed, ensuring its adaptability for modern portable and wearable energy storage devices.