Self-healable and eco-friendly hydrogels for flexible supercapacitors

One limitation of wearable electronics, and at the same time a challenge, is the lack of energy storage devices with multiple functionalities produced using clean and environmental-friendly strategies. Here, a multifunctional conductive hydrogel containing poly(3,4-ethylenedioxythiophene) (PEDOT) and alginate was fabricated, to be used as electrodes in supercapacitors, by applying water-mediated self-assembly and polymerization processes at room temperature. The interpenetration of both polymers allowed combining flexibility and self-healing properties within the same hydrogel together with the intrinsic biocompatibility and sustainability of such materials. Initially, PEDOT : polystyrene sulfonate and alginate aqueous solutions were mixed in two different proportions (1:1 and 1:3) and ionically cross-linked with CaCl2. Subsequently, re-interpenetration of poly(hydroxymethyl-3,4-ethylenedioxythiophene) (PHMeDOT) by anodic polymerization in CaCl2 aqueous solution was achieved. Re-interpenetrated 1:3 PEDOT/alginate hydrogels showed excellent capacitance values (35 mF/cm2) and good capacitance retention. On the other hand, the electrochemical properties were not significantly changed after many cutting/self-healing cycles as was observed by cyclic voltammetry. Therefore, this sustainably produced hydrogel shows promising properties as wearable energy storage devices.
Postprint (author's final draft)