Ultralong-Cycling and Free-Standing Carboxylated Graphene/PEDOT:PSS Films as Electrode for Flexible Supercapacitors

The rapid development of current wearable electronics motivates the promotion of energy storage devices. Supercapacitor with flexible, lightweight, highly efficient, and long cycling life is one of the potential and glittering candidates. Here, the composite film of carboxylated graphene (CG) and commercially available poly (3, 4-ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) are prepared as electrodes for flexible electrochemical capacitors by ultrasonication and vacuum filtration. The CG/PEDOT:PSS films were roundly characterized by SEM, XPS, FTIR, XRD and Raman spectrometer. The as-prepared free-standing films exhibited high specific capacitance (192.7 F g(-1) at 0.5 A g(-1)), excellent rate capability (up to 80.4% from 0.5 to 20 A g(-1)), and good electrochemical stability (95.5% of specific capacitance retention after 50000 cycles). Surprisingly, the post treated free-standing films by Dimethyl Formamide (DMF) shows better capacitive properties than those of the pristine electrode, such as higher specific capacitance (204.3 F g(-1) at 0.5 A g(-1)), and ultralong-cycling stability (104.6% retention at a high current density of 20 A g(-1) after 50000 cycles). It is expected that the free-standing CG/PEDOT:PSS films can be used as flexible electrodes for various wearable energy storage devices.