Flexible and transparent supercapacitors using electrospun PEDOT:PSS electrodes

Electrospun poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT: PSS) nanofibers were deposited onto flexible polyethylene terephthalate (PET) substrates to obtain electrodes for flexible and all solid-state supercapacitors (SCs). The solution used for electrospinning contained a conducting polymer (PEDOT:PSS), an insulating polymer (polyethylene oxide or PEO), a solvent (dimethylformamide) and a surfactant (Triton-X). The nanofibers improved considerably their conductivity when they were immersed in ethylene glycol (EG), producing a removal of the excedent of PEO around the nanofibers, which causes that the PEDOT:PSS nanofibers became more conductive, then improving their electrochemical performance. The removal of PEO was observed by scanning electronmicroscopy (SEM) and corroborated by energy-dispersive X-ray spectroscopy (EDS). The PEDOT:PSS electrodes were used in supercapacitors, with poly (vinyl alcohol)/phosphoric acid (PVA/H3PO4) gel polyelectrolyte, forming an all solid-state SC. The SCs reach an areal capacitance of 1.8 m F/cm2 and a gravimetric capacitance of 3.6 F/g at a discharging current of 5μA/cm2 by galvanostatic charge discharge technique (GCD). The capacitances of the SCs were also calculated by cyclic voltammetry showing very similar results than GCD. These results using PEDOT:PSS nanofibers as electrodes showed better performance in comparison with doped PEDOT:PSS films with the same gel polyelectrolyte. The devices showed very good stability since they were charged and discharged at 20 μA /cm2 by 1000 cycles maintaining ∼92 % of the initial capacitance. These results open the possibility of fabricating wearable and 3-D interconnected electrodes for energy-storage devices that could be implemented on clothes and on any non-flat surface.