Synergistic phase regulation and heterojunction engineering achieve ultrahigh-energy density in ferroelectric polymers

Ferroelectric polymers are constrained in high-power energy storage capacitors (ESCs) due to their hysteresis losses and low breakdown strength. We tackle this challenge via a dual-pronged strategy encompassing molecular-scale ferroelectric phase regulation and nanoscale heterojunction engineering. The incorporation of trifluoroethylene units into poly(vinylidene fluoride)-chlorotrifluoroethylene disrupts the ferroelectric long-range order, inducing a relaxor state with dynamic polar nanoregions (PNRs) to minimize hysteresis. Simultaneously, ZnO@ZnS nanoparticles refine PNRs and introduce deep charge traps via interfacial band engineering, thereby drastically suppressing electrical conduction. This synergistic strategy employs phase regulation to reduce dipolar loss and heterojunction engineering to curb conduction loss, leading to a greatly increased breakdown strength and reduced dissipation. The resulting nanocomposite achieves a high discharged energy density of 23.8 J cm−3 at 550 MV m−1 with 80% efficiency and robust cycling stability (>5000 cycles) and establishes a transformative pathway for ultrahigh-performance ESCs.