Self-healable poly (N, N-dimethylacrylamide)/poly (3,4-ethylenedioxythiophene) polystyrene sulfonate composite hydrogel electrolytes for aqueous supercapacitors

Abstract

The composite hydrogel electrolytes have been developed by in situ free radical polymerization of N, N dimethylacrylamide in the presence of sodium montmorillonite (Na-MMT) as a physical crosslinking agent and magnesium trifluoromethanesulfonate (MgTf2) as an ionic source to improve their conductivity. Moreover, the incorporation of highly conductive poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) enhanced the electrochemical performance and increased the conductivity by providing conduction pathways through the PEDOT:PSS chains. The formation of composite hydrogel electrolytes was confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, and thermogravimetric analysis (TGA). The surface morphology was observed using field emission scanning electron microscopy, and energy dispersive X-ray (EDX) analysis was carried out to find the elements present. The ionic conductivity was studied at room temperature and temperature ranging from 303 K to 373 K. PEDOTDMA35 achieved the maximum ionic conductivity at room temperature (8.6 × 10−3 S/cm) and in the entire temperature range i.e., from 303 K to 373 K. Electrochemical performance of the symmetric supercapacitors was carried out at different scan rates (3 to 100 mV/s) and different current densities (100 to 500 mA/g) to calculate the specific capacitance, energy density, and power density. AC/PEDOTDMA35/AC attained the highest specific capacitance of 280 F/g at 3 mV/s and 376.6 F/g at 100 mA/g (energy density ∼52.35 Wh/kg and power density ∼100.08 W/kg). In addition, prototype supercapacitor was fabricated and used to light up the light emitting diode (LED). The self-healing efficiency of the composite hydrogel electrolyte was also investigated. The results indicate that synthesized hydrogel electrolytes have the potential to be used in aqueous flexible and self-healable supercapacitors.