Wrinkled Polypyrrole Aggregates Grown on Elastic Polymers as Electrodes for High-Performance Stretchable Supercapacitors

Attaching electroactive polymer on elastomer is a facile way to construct a stretchable electrode, but maintaining the interface robustness of the heterogeneous components remains a challenge. Herein, porous polypyrrole (PPy) is firmly fixed on elastic poly(hydroxyethyl acrylate)-co-poly(N-hydroxyethyl acrylamide) (PHEA-co-PHEAA) by two-stage polymerization to prepare a stretchable electrode PPy@PHEA-co-PHEAA. The first-stage polymerization of PPy is performed in a PHEA-co-PHEAA hydrogel, and the second one is performed on the surface of prestrained PHEA-co-PHEAA in the presence of surfactant sodium dodecyl sulfate (SDS) self-assembly. Micro wrinkles consisting of globular PPy aggregates are constructed on the electrode surface to adapt the elongation by unfolding. The firm fixation of PPy on PHEA-co-PHEAA ensures the interconnected globular PPy aggregate is well preserved under stretch conditions. PPy@PHEA-co-PHEAA exhibits an electrical conductivity of 81.5 S cm–1 and a stretchability of 293%. The supercapacitor assembled from PPy@PHEA-co-PHEAA and an acid hydrogel electrolyte delivers a specific capacitance of 1003 mF cm–2 and a capacitance retention of 89.4% after 2000 stretch–release cycles at a strain of 100%. Embedding electroactive aggregates in elastic substrates by sequential polymerization offers a general strategy to construct stretchable electrodes for wearable supercapacitors.