Flexible Electrodes for Supercapacitors Based on the Supramolecular Assembly of Biohydrogel and Conducting Polymer

Flexible and lightweight electrodes were prepared using a two-step process. First, poly­(3,4-ethylenedioxythiophene) (PEDOT) microparticles were loaded into poly-γ-glutamic acid (γ-PGA) hydrogel matrix during the reaction of the biopolymer chains with the cross-linker, cystamine. After this, PEDOT particles dispersed inside the hydrogel were used as polymerization nuclei for the chronoamperometric synthesis of poly­(hydroxymethyl-3,4-ethylenedioxythiophene) (PHMeDOT) in aqueous solution. After characterization of the resulting electrode composites, electrochemical studies revealed that the capacitive properties drastically depend on the polymerization time used to produce PHMeDOT inside the loaded hydrogel matrix. Specifically, flexible electrodes obtained using a polymerization time of 7 h exhibit an specific capacitance of 45.4 ± 0.7 mF/cm2 from cyclic voltammetry and charge–discharge long-term stability. The applicability of these electrodes in lightweight and flexible energy-harvesting systems useful for energy-autonomous, low-power, disposable electronic devices has been proved powering a LED bulb.