Prototyping flexible supercapacitors produced with biohydrogel

Flexible symmetric supercapacitor prototypes composed of electrodes that were prepared by polymerizing poly(hydroxymethyl-3,4-ethylenedioxythiophene) inside a poly-γ-glutamic acid (γPGA) biohydrogel matrix, previously loaded with microparticles of poly(3,4-ethylenedioxythiophene) (PEDOT) and alumina (Al2O3), have been fabricated and characterized. Prototypes have been assembled in a totally solid, compact and lightweight configuration, where the supporting electrolytic medium is a γPGA hydrogel prepared in presence of NaHCO3. The elements of the prototypes have been characterized and their optimized to obtain the highest specific capacitance. The electrochemical performances of the prototypes have been investigated by cyclic voltammetry, charge-discharge galvanostatic cycles and electrochemical impedance spectroscopy. After 2000 charge-discharge cycles (i.e. 60.000 s of continuous operation), the loss of specific capacitance is of only 8%, revealing an excellent stability. Results are very promising for the development of compact, flexible, lightweight and biocompatible supercapacitors to be employed like energy-autonomous electronic devices.