A stretchable and self-healable conductive hydrogels based on gelation/polyacrylamide/polypyrrole for all-in-one flexible supercapacitors with high capacitance

Conductive polymeric hydrogels have aroused growing attentions for their promising applications in wearable electronics. It is still necessary to harmonize their mechanical and electrochemical properties for the real applications. Here we report novel conductive hydrogels with a sandwich-like structure, in which gelatin/polyacrylamide (Gel/PAAM) double network are served as robust scaffold and polypyrrole (PPy) nanoclusters were firmly embedded in the two sides of the Gel/PAAM hydrogel. The obtained Gel/PAAM/PPy hydrogels have shown a skin-like stretchable and high conductivity under various deformations. Significantly, the PPy content in the Gel/PAAM/PPy hydrogels can be easily regulated for the use in flexible all-in-one supercapacitors (SCs). The optimized device showed an exceptional specific capacitance of 363.75 mF/cm(2), a high energy density of 32.33 mu W h/cm(2) at power density of 400 mu W/cm(2), as well as a promising cyclic stability of 82% capacitance retention after 2000 cycles. Besides, the working potential window and output current density can be extended by assembling the single SC into series and parallel connection. What' more, the device possesses very stable electrochemical performance under bending, compressing, stretching conditions and even after healing process. This work proposes a feasible approach for preparation of novel PPy-based conductive hydrogels that might provide a viable source for all-flexible electronic devices.