Conductive-Polymer-Based Double-Network Hydrogels for Wearable Supercapacitors

In the field of contemporary epidermal bioelectronics, there is a demand for energy supplies that are safe, lightweight, flexible and robust. In this work, double-network polymer hydrogels were synthesized by polymerization of 3,4-ethylenedioxythiophene (EDOT) into a poly(vinyl alcohol)/poly(ethylene glycol diacrylate) (PVA/PEGDA) double-network hydrogel matrix. The PEDOT-PVA/PEGDA double-network hydrogel shows both excellent mechanical and electrochemical performance, having a strain up to 498%, electrical conductivity as high as 5 S m^-1 and specific capacitance of 84.1 ± 3.6 mF cm⁻². After assembling two PEDOT-PVA/PEGDA double-network hydrogel electrodes with the free-standing boron cross-linked PVA/KCl hydrogel electrolyte, the formed supercapacitor device exhibits a specific capacitance of 54.5 mF cm⁻² at 10 mV s^-1, with an energy density of 4.7 μWh cm^-2. The device exhibits excellent electrochemical stability with 97.6% capacitance retention after 3000 charging-discharging cycles. In addition, the hydrogel also exhibits great sensitivity to strains and excellent antifouling properties. It was also found that the abovementioned hydrogel can achieve stable signals under both small and large deformations as a flexible sensor. The flexible and antifouling PEDOT-PVA/PEGDA double-network hydrogel-based supercapacitor is a promising power storage device with potential applications in wearable electronics.