Self-Healing, Methyl-Copolymerized Polyaniline Electrodes with Enhanced Durability and Capacitance

Polyaniline (PANI) is a promising electrode material for supercapacitors, yet its dense π–π stacking and rigid backbone hinder proton transport and cause structural degradation during cycling. Here, we introduce a dual-scale design combining methyl-substituted copolymerization with a self-healing ionic regulator (SIR). Copolymerizing N -phenyl- p -phenylenediamine with m -toluidine forms poly(AD- co -mT) (PACM), where the methyl steric effect loosens chain packing and enhances H + diffusion, delivering 850 F g –1 at 1 A g –1 . Incorporating SIR─a hydrogen-bond-rich polymer that regulates ion transport while acting as a dynamic adhesive phase─reconnects cycling-induced microcracks and sustains electronic pathways. Mechanistically, the methyl-induced interchain loosening and hydrogen-bond-mediated self-repair act cooperatively to maintain charge transport during long-term cycling. Benefiting from this synergy, PACM-SIR symmetric devices achieve 158 F g –1 with 84% retention after 30000 cycles, and the PACM-SIR//AC flexible device maintains stable operation under bending and 0–50 °C. This molecular-to-mesoscale design provides a general route to durable, high-rate conducting-polymer electrodes.