Graphene and Poly (3,4-ethylenedioxythiophene) (PEDOT) based Hybrid Supercapacitors with Ionic Liquid Gel Electrolyte in Solid State Design and their Electrochemical Performance in Storage of Solar Photovoltaic Generated Electricity

Abstract

ABSTRACTIn this work, ionic liquid gel polymer electrolyte is used to fabricate solid-state hybrid supercapacitors with microporous PEDOT and graphene asymmetric electrodes. The PEDOT electrode was prepared by ultra-short pulsed current electro-polymerization over flexible graphite sheets. The graphene electrode of 600 m2g-1 surface area was formed by slurry coating using graphene platelets of thickness 8 nm and size <2 μm. The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF4) was mixed with poly(vinylidene fluoride-hexafluoropropylene) P(VdF-HFP) to form gel electrolyte. The quasi rectangular cyclic voltammetry (CV) plots in the voltage range -0.2 to +2.0V and the charge-discharge (CD) curves show highly capacitive behavior. The optimized 0.1M LiClO4 doping of IL gel electrolyte increases specific capacitance to 70.4 mF.cm-2. Increase in IL electrolyte thickness from 30 to 54 µm improves discharge capacitance from 10.6 to 23.3 mF.cm-2 and energy density from 2.90 to 5.86 Wh.kg-1. Hybrid solid-state supercapacitor has a flat stackable platform which easily integrates with solar cell module for direct storage of solar electricity. This paper describes the electrode synthesis, design and electrochemical properties of PEDOT/graphene hybrid supercapacitor and the charging characteristics by solar cells for evaluating energy storage performance in backing up the solar cell generated electricity.