Enhanced Dielectric Reliability of Recyclable Polyimide Film Enabled by Dynamic Disulfide Bond Exchange.

The growing demand for highly reliable dielectric film capacitors in advanced electrical and electronic systems has driven the investigation of polymer films capable of maintaining stable charge-discharge cyclic performance under continuous electrical stress. Here, a disulfide-functionalized polyimide (PI) film with dynamic reversible network is developed, achieving substantially improved long-term reliability at room temperature under high electric fields. The synergistic multi-level defense mechanism involves sulfur radicals from disulfide bond cleavage acting as deep trapping sites to immobilize charge carriers and suppress electrical treeing propagation, while flexible polydimethylsiloxane (PDMS) segments facilitate the migration to enable radical recombination for structural recovery and defect healing. The intrinsically wide bandgap of the optimized PI film further imposes a large energy barrier for carrier injection, and the resultant PI film delivers a superior discharged energy density of 12.7 J cm-3 with efficiency of 91.1% at 900 MV m-1. The recycled PI film demonstrates the exceptional cycling robustness over 105 charge-discharge cycles with efficiency >90% at 200 MV m-1. This work provides fundamental insights into dynamic bond chemistry for enhancing room-temperature dielectric reliability in polymer dielectrics.