Flexible and Self-Healable Supercapacitor with High Capacitance Restoration

This work reports on the fabrication of a flexible and self-healing high-performance quasi-solid-state supercapacitor that uses a conductive composite electrode. The supercapacitor employs an active layer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT/PSS)-multiwalled carbon nanotube (MWNT)-coated polyurethane/carbon black composite electrode sandwiched with a poly(vinyl alcohol) (PVA)/H₃PO₄ gel electrolyte. The supercapacitor possesses the highest capacitance over 47 mF cm^-2 and a high energy density from 5.8 to 1.7 μWh cm^-2 with the corresponding power density changing from 0.13 to 0.61 W cm^-2 at a current density from 1 to 8 mA cm^-2. The supercapacitor can retain up to 94% of its electrochemical performance even after a fifth severing/healing cycle, and using capacitance retention, it maintains mechanical stability under various bending deformations. As a result, this self-healing supercapacitor features device-level toughness with more than 96% areal capacitance conserved, even under 180° bending (1.6 mm of bending radius). With its high durability and longevity against dynamic deformation and damage, our study demonstrates the high application potential of this supercapacitor in portable/wearable electronics.